What are the common tests for liver problems in children. How do ultrasounds and CT scans help diagnose liver issues. What is the purpose of a liver biopsy. How does ERCP aid in detecting bile duct abnormalities. What is the significance of blood tests in liver disease diagnosis.

Understanding Liver Disease Testing in Children: An Overview

Liver disease in children can be a complex and concerning issue for parents and healthcare providers alike. Accurate diagnosis is crucial for effective treatment and management. This comprehensive guide delves into the various tests and procedures used to assess liver health and function in pediatric patients.

Healthcare providers employ a range of diagnostic tools to evaluate liver problems in children. These tests not only examine the liver itself but also assess related organs and tissues, such as the gallbladder and bile ducts. By understanding these tests, parents can better navigate the diagnostic process and support their child’s healthcare journey.

Imaging Techniques for Liver Disease Diagnosis

Imaging plays a crucial role in diagnosing liver diseases in children. These non-invasive techniques provide valuable insights into the structure and function of the liver and surrounding organs.

Ultrasound: A Window into Liver Health

Ultrasound, also known as sonogram, is often the first-line imaging test for liver assessment in children. This painless procedure uses sound waves to create real-time images of the liver and surrounding structures.

• Can detect bile leakage (bile lakes) within the liver
• Identifies gallstones
• Provides a clear view of liver size and texture
• Helps guide other procedures, such as liver biopsies

How does ultrasound work in liver disease diagnosis? The sound waves emitted by the ultrasound probe bounce off liver tissues, creating detailed images that reveal abnormalities. This technique is particularly useful for detecting fluid-filled structures and solid masses within the liver.

CT Scan: 3D Visualization of Liver Abnormalities

Computed tomography (CT) scans offer a more detailed, three-dimensional view of the liver and gallbladder. This advanced imaging technique uses X-rays and computer processing to create cross-sectional images of the body.

• Detects gallstones that may be missed by ultrasound
• Identifies liver abscesses and tumors
• Reveals abnormal blood vessels in the liver
• Provides detailed information about liver structure and surrounding organs

When is a CT scan preferred over ultrasound for liver assessment? CT scans are often used when more detailed imaging is required, particularly for complex cases or when planning surgical interventions. They can provide a comprehensive view of the entire abdominal region, allowing for better assessment of liver-related complications.

Liver Biopsy: A Closer Look at Liver Tissue

While imaging techniques provide valuable information about liver structure, a liver biopsy offers direct insight into the health of liver tissue at a cellular level. This procedure involves removing a small sample of liver tissue for laboratory analysis.

The Liver Biopsy Procedure

1. The liver is visualized using ultrasound or CT guidance
2. A special needle is inserted through the skin into the liver
3. A small tissue sample is extracted
4. The sample is sent to a laboratory for analysis

What can a liver biopsy reveal? This procedure provides detailed information about liver health, including:

• Signs of inflammation
• Presence and extent of scarring (fibrosis or cirrhosis)
• Evidence of specific liver diseases
• Abnormal accumulation of substances in liver cells

Why might a healthcare provider recommend a liver biopsy for a child? Liver biopsies are typically performed when less invasive tests are inconclusive or when more detailed information about liver tissue is needed to guide treatment decisions. This procedure can be particularly valuable in diagnosing rare liver conditions or assessing the severity of liver damage.

ERCP: Exploring the Biliary System

Endoscopic Retrograde Cholangiopancreatography (ERCP) is a specialized procedure that combines endoscopy and X-ray imaging to examine the bile ducts, pancreatic duct, and gallbladder. This test is particularly useful for diagnosing and treating problems in the biliary system.

The ERCP Procedure

1. A flexible endoscope is inserted through the mouth
2. The scope is guided through the esophagus and stomach to the small intestine
3. Contrast dye is injected into the bile ducts
4. X-ray images are taken to visualize the biliary system

What conditions can ERCP diagnose in children? This procedure is particularly effective in identifying:

• Blockages or narrowing in the bile ducts
• Gallstones lodged in the bile ducts
• Tumors affecting the biliary system
• Congenital abnormalities of the bile ducts

How does ERCP differ from other imaging techniques? Unlike ultrasound or CT scans, ERCP allows for both diagnosis and potential treatment in a single procedure. For example, if a gallstone is found blocking a bile duct, it can often be removed during the ERCP procedure.

Advanced Imaging Techniques: HIDA Scan and MRCP

As medical technology advances, new imaging techniques offer even more detailed insights into liver and biliary system function. Two such advanced procedures are the HIDA scan and Magnetic Resonance Cholangiopancreatography (MRCP).

HIDA Scan: Assessing Gallbladder Function

The Hepatobiliary Iminodiacetic Acid (HIDA) scan is a nuclear medicine procedure that evaluates the function of the gallbladder and liver. This test involves injecting a small amount of radioactive tracer into the bloodstream.

• Tracks the flow of bile from the liver to the small intestine
• Detects blockages in the bile ducts
• Assesses gallbladder function and emptying
• Identifies congenital abnormalities of the biliary system

When is a HIDA scan recommended for children? Healthcare providers may order this test when there are concerns about gallbladder function or suspected bile duct obstructions. It’s particularly useful in cases where other imaging tests have been inconclusive.

MRCP: Detailed Imaging Without Radiation

Magnetic Resonance Cholangiopancreatography (MRCP) is a specialized type of magnetic resonance imaging (MRI) that provides detailed images of the biliary and pancreatic ducts without using radiation or contrast dyes.

• Creates high-resolution images of the bile ducts, pancreas, and gallbladder
• Detects abnormalities in bile duct structure
• Identifies gallstones, even small ones
• Reveals signs of chronic pancreatitis or pancreatic tumors

How does MRCP compare to ERCP? While ERCP is both diagnostic and therapeutic, MRCP is purely a diagnostic tool. However, MRCP is non-invasive and doesn’t carry the risks associated with ERCP, such as pancreatitis. It’s often used as a preliminary test before deciding if ERCP is necessary.

Blood Tests: The Foundation of Liver Disease Diagnosis

Blood tests play a crucial role in assessing liver health and function. These tests can provide valuable information about liver enzyme levels, protein production, and other markers of liver disease.

Key Blood Tests for Liver Assessment

1. Alpha-fetoprotein (AFP)
2. Albumin
3. Alkaline phosphatase (AP)
4. Alanine aminotransferase (ALT)
5. Aspartate aminotransferase (AST)
6. Bilirubin
7. Gamma-glutamyl transferase (GGT)

What can these blood tests reveal about liver health? Each test provides specific insights:

• AFP: Elevated levels in older children may indicate liver cancer
• Albumin: Low levels can suggest impaired liver function
• AP: High levels may indicate bile duct obstruction or liver damage
• ALT and AST: Elevated levels indicate liver cell damage
• Bilirubin: High levels can indicate liver dysfunction or bile duct obstruction
• GGT: Elevated levels may suggest bile duct or liver disease

How often should liver function blood tests be performed in children with suspected liver disease? The frequency of testing depends on the child’s specific condition and treatment plan. In some cases, regular monitoring may be necessary to track disease progression or response to treatment.

Interpreting Liver Test Results: A Holistic Approach

Diagnosing liver disease in children requires a comprehensive approach that considers multiple factors. Healthcare providers analyze the results of various tests in conjunction with the child’s medical history, physical examination findings, and symptoms.

Factors Influencing Test Interpretation

• Age of the child
• Presence of other medical conditions
• Medications the child is taking
• Family history of liver disease
• Recent illnesses or infections

Why is a holistic approach important in diagnosing pediatric liver disease? Liver test results can be influenced by various factors, and a single abnormal result doesn’t necessarily indicate liver disease. By considering all available information, healthcare providers can make more accurate diagnoses and develop appropriate treatment plans.

How do healthcare providers determine which tests are necessary for each child? The selection of tests is based on the child’s symptoms, risk factors, and initial test results. A stepwise approach is often used, starting with less invasive tests and progressing to more specialized procedures as needed.

Emerging Technologies in Pediatric Liver Disease Diagnosis

As medical research advances, new technologies are being developed to improve the diagnosis and monitoring of liver diseases in children. These innovative approaches aim to provide more accurate, less invasive, and more child-friendly diagnostic options.

Promising Diagnostic Advancements

• Elastography: Measures liver stiffness to assess fibrosis without biopsy
• Metabolomics: Analyzes metabolites in blood or urine to detect liver dysfunction
• Genetic testing: Identifies inherited liver disorders and predisposition to certain conditions
• Artificial intelligence: Enhances interpretation of imaging studies and laboratory results

How might these emerging technologies change the landscape of pediatric liver disease diagnosis? These advancements have the potential to provide earlier detection, more precise diagnoses, and better monitoring of treatment responses. They may also reduce the need for invasive procedures, making the diagnostic process less stressful for children and their families.

What challenges exist in implementing these new technologies in pediatric liver care? While promising, many of these technologies are still in the research phase or early stages of clinical implementation. Factors such as cost, accessibility, and the need for specialized expertise may impact their widespread adoption.

The field of pediatric liver disease diagnosis continues to evolve, with ongoing research aimed at improving our understanding of liver disorders and developing more effective diagnostic tools. As new technologies emerge and our knowledge expands, the ability to accurately diagnose and effectively treat liver diseases in children will undoubtedly improve, offering hope to families facing these challenging conditions.

Liver Disease Testing in Children

This sheet describes common tests that
may be done for liver problems. Your child’s healthcare provider will tell you which
of
these tests your child needs.

Tests to check the liver

Several tests can check the health
and function of the liver. They can also check the health and function of related
organs
and tissues, such as the gallbladder or bile ducts. They include:

• Ultrasound. This is also called a
  sonogram. It uses sound waves to show a picture of the liver. It can show areas of
  bile leaking out of the liver (bile lakes) and gallstones.

• CT scan.  This shows a 3-D picture
  of the liver and gallbladder. This can show some gallstones, abscesses, abnormal
  blood vessels, or tumors.

• Liver biopsy. This is a procedure
  that looks for damage in liver tissue. The liver is looked at using a CT scan or
  ultrasound. A needle is used to remove a small amount of tissue from the liver.
  This is studied in the lab for signs of inflammation, scarring, or other
  problems.

• ERCP (endoscopic retrograde
  cholangiopancreatography).
  This is a procedure that can show blockage or
  narrowing in the bile ducts. A small, flexible tube (endoscope) is put into the
  mouth. It’s moved through the esophagus and stomach to the top of the small
  intestine. This is where the bile ducts meet the intestine. Dye is put through the
  scope to make the bile ducts show up on an X-ray. The healthcare provider may take
  samples of tissue or fluid using instruments inserted into the scope. The samples
  are sent to the lab to be studied.

• HIDA (hepatobiliary iminodiacetic acid)
  scan.
  This checks the function of your child’s gallbladder or liver. A
  radioactive fluid called a marker is put into the body. As this marker travels
  through the liver to the gallbladder and into the intestine, it can be seen on a
  scan. The marker can show if bile ducts are missing or blocked, and other
  problems.

• MRCP (magnetic resonance
  cholangiopancreatography).
  This is an imaging test that uses strong
  magnets to create pictures of the bile ducts, pancreas, and gallbladder. It can
  reveal abnormal bile ducts, narrowed bile ducts, or gallstones.

Blood tests to check the liver

A small amount of blood may be
taken and tested to check one or more of the following:

• Alpha fetoprotein (AFP). This is
  normally high in newborns. But high levels in the blood of an older child can be a
  sign of liver cancer.

• Albumin. This is a protein made by
  the liver. It can be measured with a blood test. When a person has liver disease,
  the level of albumin in the blood (serum albumin) is often low.

• Alkaline phosphatase (AP). This is
  an enzyme made in the liver and bone. It’s measured with a blood test. A high
  level may mean there’s a problem with the bile ducts in the liver.

• Alanine aminotransferase
  (ALT).
   This is an enzyme made by the liver. When the liver is damaged, ALT
  leaks into the blood. If a blood test finds a high level of ALT, this can be a
  sign of liver problems, such as inflammation, scarring, or a tumor.

• Ammonia. This is a harmful
  substance left behind in the blood after digestion. Normally, the liver removes
  ammonia from the blood and turns it into urea. This leaves the body with urine. If
  a blood test shows that the ammonia level is too high, this process isn’t
  happening as it should.

• Aspartate aminotransferase (AST).
  This is another enzyme made by the liver and also made by other organs. High
  levels suggest liver injury, especially if the ALT level is also high.

• Bilirubin. This is a yellow
  substance made when the body breaks down red blood cells. It’s collected by the
  liver to be sent out of the body with stool. When something is wrong with the
  liver or bile ducts, bilirubin may build up in the body. This causes yellowing of
  the skin and the whites of the eyes (jaundice). Two measurements may be taken:
  total bilirubin and direct bilirubin. A high total bilirubin level means the liver
  isn’t breaking down bilirubin. A high direct bilirubin level suggests a blockage
  in the bile ducts.

• Complete blood count (CBC). This
  is a test that measures all the parts of the blood: red blood cells, white blood
  cells, and platelets. Problems with these counts can mean infection or illness.
  They can also be a sign of a problem with the spleen. This is an organ close to
  the liver that can be affected by liver disease.

• Essential fatty acids
  (EFAs).
   These are important nutrients. EFA levels may be lower when the liver
  is diseased. This is because the liver can’t absorb and transport EFAs as it
  should.

• Gamma-glutamyl transpeptidase (GGT).

  This is an enzyme that’s often measured along with other enzymes to gauge
  liver problems. GGT is measured with a blood test. If AP and GGT are both high,
  this is a sign that the bile ducts in the liver may be diseased or blocked.

• Glucose. This is sugar in the
  blood. A healthy liver helps the body keep a normal glucose level. If a blood test
  reveals that glucose is low, this may mean the liver is not working correctly.

• Coagulation studies (PT & INR)
  These test the ability of the blood to clot. The liver makes a protein that helps
  with clotting. Problems with clotting can be a sign of liver disease.

• Serum bile acid (SBA). This is the
  amount of bile acids in the blood. A high level may mean that bile ducts are
  blocked.

• Vitamins A, D, E, and K. These are
  fat-soluble vitamins that are absorbed by the liver, with help from bile. If a
  blood test shows that levels of these vitamins are low, this could mean your
  child’s liver is not absorbing them correctly.

• Zinc.  This is a nutrient that is
  absorbed by the liver. If a blood test shows that your child’s zinc level is low,
  this could mean the liver isn’t absorbing zinc correctly.

Essential Tests for Staying on Top of Chronic Liver Disease

GettyImages/SolStock

If you have been diagnosed with chronic liver disease (CLD)—technically defined as a progressive deterioration of liver function for more than six months—you aren’t alone. It’s a common diagnosis (non-alcoholic fatty liver disease is the most prevalent type) with multiple potential causes, including toxins, alcohol abuse, cancer, infection, autoimmune diseases, genetic links, and metabolic disorders.

Once you are diagnosed with chronic liver disease, your provider will work to determine the cause and come up with a treatment plan. Considering that many people with chronic liver disease are mainly asymptomatic, it can be hard to know if treatment is effective based on symptoms alone. That’s why it’s important for your doctor to monitor the health of your liver over time to see how well your treatment is working. While the exact liver disease tests your provider gives you will vary, these are some of the most common ones that your doctor may use to monitor the health of your liver.

Alanine Transaminase (ALT) Test

This test measures the level of alanine aminotransferase, an enzyme found mostly in the liver, that gets released into the bloodstream. This blood test can be an essential part of a larger evaluation known as the Fibrosis-4 Index, which measures inflammation and scarring of the liver, explains Kenneth Cusi, M.D., a professor of medicine at the University of Florida in Gainesville. According to Dr. Cusi, approximately 70% of those with type 2 diabetes and obesity will have fat in their livers; this test helps determine if that fat is putting someone at risk for liver fibrosis and more serious health issues.

Aspartate Transaminase (AST) Test

This test measures the level of an enzyme known as aspartate transaminase. This enzyme is found throughout your body and is released into the bloodstream after acute liver cell damage. The AST test is also commonly used to help determine the Fibrosis-4 Index, according to Dr. Cusi.

Platelet Count

In addition to the ALT and AST tests, your blood platelet count is also needed to determine your Fibrosis-4 Index and possible level of liver inflammation, says Dr. Cusi. A platelet count is typically measured with a simple blood test to determine how many platelets are in your blood. Together, the ALT, AST, and platelet count can be used to determine the level of inflammation in the liver and whether or not you are at low, moderate, or high risk for advanced liver disease, according to Dr. Cusi.

Serum Alkaline Phosphatase (ALP) Test

This test is used to measure the level of alkaline phosphatase in the blood. This enzyme is found throughout your body, including your liver. Elevated levels are an indication of chronic liver disease, but this blood test may also be performed to assess liver functioning and to find liver lesions that could cause biliary obstruction, such as tumors or abscesses.

Gamma-Glutamyl Transpeptidase (GGT) Test

This test measures the level of the enzyme gamma-glutamyl transpeptidase. According to the Mayo Clinic, this test is also performed to assess liver function, to provide information about liver diseases, and to detect alcohol ingestion. When the liver is damaged, GGT may leak into the bloodstream; as such, elevated levels in your blood test are one way your doctor might determine the cause of your liver disease.

Hepatitis B Surface Antigen (HBSAG) Test

This is one of the tests that could help your doctor determine if you might have chronic hepatitis B. (Other tests are needed to confirm a chronic hep B infection.) Hepatitis B is a disease of the liver caused by infection with the hepatitis B virus.

Prothrombin Time (PT) Test

This test measures how long it takes for a sample of your blood to clot, a process that involves proteins that your liver produces. Because blood clotting needs vitamin K and a protein that is made by the liver, a prolonged amount of time for clotting to occur may indicate liver disease or other deficiencies in specific clotting factors, according to Johns Hopkins Medicine.

Alpha-Fetoprotein (AFP) Tumor Marker Test

As the name indicates, this test is one way your doctor will try and distinguish between chronic liver disease and liver cancer. According to the National Cancer Institute, an increased level of AFP in the blood may be a sign of liver cancer. But because certain noncancerous conditions, including cirrhosis and hepatitis, may also increase AFP levels, this test alone is never enough to make a clear diagnosis.

Additional Diagnostics for Chronic Liver Disease

While the more common tests mentioned above can begin to give your provider information about your liver condition—both the extent of your liver disease and how your treatment is working—they are not the only tools medical professionals will use, says Dr. Cusi. If your provider suspects your disease is severe or is worsening, you may be referred to a hepatologist, a doctor who specializes in treating acute and chronic liver diseases. Under the care of a hepatologist, more information may be determined with the following tests:

• Elastography: This test is used to check the thickness and elasticity of the liver. It can help your doctor more accurately determine your liver’s health: The thicker your liver is in the test, the greater the odds of fibrosis (scarring) of the organ. This is a non-invasive test typically performed via ultrasound or magnetic resonance imagery (MRI).

• Enhanced liver fibrosis (ELF) test: The ELF blood test can help your doctor determine the severity of your liver disease.

The Future of Chronic Liver Disease Tests

It’s possible that in the near future, the health of your liver can be monitored from outside your body, according to Rakesh Jain, Ph.D., a professor of tumor biology and radiation oncology at Harvard Medical School in Boston, MA. Jain and his colleagues have been working on a non-invasive method of measuring liver health by using infrared lighting on the outside of the body as a screening tool or to monitor progress of liver disease.

Today, the technology is only showing promise in mice models, but according to Jain, practical applications of this technology in people may be near. “With ongoing investigations, we anticipate that this method will be translated into the clinic as a non-invasive biomarker for monitoring patients with non-alcoholic liver disease and other chronic liver diseases,” he says. The method would give doctors a much-needed tool for monitoring patients with chronic liver disease: Jain notes that while tests such as a liver biopsy can provide diagnostic information, they are not practical or feasible as a regular means of monitoring disease progression.

If you are being tested for chronic liver disease, or your doctor is simply monitoring your condition and seeing whether your medications are doing their job, any of these tests are possible. Don’t be afraid to ask questions about which ones you’re getting and why—the more you know about your condition, the better equipped you’ll be to stay one step ahead of chronic liver disease.

Gamma-glutamyl transpeptidase (GGT) test: Mayo Clinic. (2023.) “Liver Function Tests. ” https://my.clevelandclinic.org/health/diagnostics/17662-liver-function-tests#:~:text=The%20most%20common%20liver%20tests,elevated%20when%20there’s%20liver%20injury.

Prothrombin Time (PT) test: Johns Hopkins Medicine. (2023.) “Common Liver Tests.” https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/common-liver-tests

Non-Invasive Monitoring: Nature Biomedical Engineering. (2020.) “Non-Invasive Monitoring of Chronic Liver Disease Via Near-Infrared and Shortwave-Infrared Imaging of Endogenous Lipofuscin.” https://www.nature.com/articles/s41551-020-0569-y

Liver Cancer: National Cancer Institute. (2022.) “Liver Cancer Diagnosis.”
https://www.cancer.gov/types/liver/what-is-liver-cancer/diagnosis#:~:text=Alpha%2Dfetoprotein%20(AFP)%20tumor,may%20also%20increase%20AFP%20levels.

Our Review Process

resolved and problematic issues (message 1)

Liver regeneration is a compensatory hyperplasia, in which processes occur in the remaining liver tissue aimed at restoring the metabolic balance in the organ [1]. Unlike true anatomical regeneration, the enlarged liver does not restore its original anatomical structure [2]. Contrary to true regeneration, in cases of resection and in some chemical models of liver injury, its cell pool is replaced by the replication of existing hepatocytes without the activation of so-called progenitor cells. In other cases, for example, in case of toxic damage to the liver by galactosamine, progenitor cells are activated and replicated [2].

Phases and timing of liver regeneration

There are 3 important distinctive phases in the mechanism of regeneration: a) the initiation phase, which consists in the overexpression of specific genes to prepare liver cells for replication; b) the proliferation phase, in which liver cells undergo a series of cycles of cell division; c) the termination phase, when inhibitors of proliferation stop it, i. e. act as a brake on the regenerative process, preventing excessive growth of liver tissue [3].

Antiproliferative factors control the rate of proliferation and determine the end point of liver regeneration. In addition, antiproliferative factors act as a “steering wheel” to keep the regeneration process in the right direction, preventing the pathological reproduction of abnormal cells, as occurs in oncogenesis. Therefore, proliferation inhibitors are just as important for ensuring safe and stable liver regeneration as factors that promote proliferation [4].

These processes are controlled by cytokines, growth factors, and signaling pathways [5]. Cytokines, including transforming growth factor β and interleukin-1, tumor suppressor genes, including p53 and p21, are important members of the proliferation inhibitor family in liver regeneration. Certain antiproliferative factors are involved in the process of gene expression and protein modification. Suppression of liver regeneration caused by metabolism, hormonal activity and pathological characteristics has been considered previously [6]. However, less is known about inhibitors of liver regeneration proliferation and further studies are needed [4].

The timing of the ongoing regeneration is being studied. So, in some studies on the model of liver resection, its dependence on circadian rhythms is shown. In this case, the transition from G2 directly to mitosis occurred at the same time of day. However, DNA synthesis peaked 36 h after surgery, regardless of the light/dark cycle. This suggests that the transition from G2 to mitosis is controlled by circadian-dependent genes associated with the cell cycle. Unlike hepatocyte mitosis, which is regulated by the circadian rhythm, DNA replication does not depend on it. Studies have shown that, after liver resection, DNA synthesis in rats reached a peak 12–16 h earlier than in mice [7].

Liver regeneration models

Liver regeneration studies are being conducted on various models. One of the most frequently used is the study of liver regeneration after liver resection. This model was proposed by Higginson in 1936 (resection ² / ₃ of the liver mass) [8]. It was noted that within 5-7 days after the removal of a part of the liver, the remaining part recovered to a size equivalent to the original mass. This is the most successful model, since the remaining part of the liver is intact from damage.

The experiment uses a model of liver damage by hepatotoxic substances such as carbon tetrachloride (CCL-4). This damage causes necrosis of the lobular zones of the liver, which leads to an acute inflammatory response, the histological picture of which is dominated by polymorphonuclear leukocytes and macrophages that penetrate the liver to remove the affected hepatocytes [6].

Acute liver damage in animals is also caused by D-galactosamine, which leads to an intracellular deficiency of uridine metabolites, and further to systemic inflammation, impaired regeneration and the development of acute liver failure (ARF) [9].

Acetaminophen intoxication is a common cause of AKI. Thus, its overdose causes an imbalance in the lipid peroxidation system, resulting in toxic accumulation of N-acetylbenzoquinone imine, leading to the formation of radicals and activation of Kupffer cells [10].

The systemic manifestation of acetaminophen hepatotoxicity is regulated by pro-inflammatory cytokines and the innate immune system. Thus, in mice with a mutant toll-like receptor (TLR4), the highest survival rate after an overdose of acetaminophen was noted compared to normal wild mice. This model shows that the survival of normal mice is improved by both depletion of Kupffer cell function and pretreatment with TLR4. Therefore, the activity of TLR4 Kupffer cells is the main factor contributing to the systemic inflammatory response of acute renal failure [11]. However, the problem remains whether there is a relationship between improved survival and the result of accelerated liver regeneration with acetaminophen intoxication.

Rare models of liver regeneration are genetically modified animals with congenital metabolic disorders. The most revealing is an immunodeficient mouse model deficient in the fumarylacetoacetate hydrolase (FAH) gene. The liver of these mice has an increased ability to increase mature hepatocytes after xenogenic transplantation [12]. R. Hickey et al. developed a special FAH medium to create high quality human hepatocytes. This in vivo environment allows primary hepatocytes to expand, to be exposed to the complex signaling systems necessary for liver regeneration, which cannot be achieved under conditions in vitro [13].

A genetically modified mouse model for hepatocyte xenotransplantation is proposed. It causes chronic liver damage and slows down the regeneration of hepatocytes. An animal model of chronic liver injury of all species, based on the administration of a recombinant adenovirus to express herpes thymidine kinase in host hepatocytes, increases sensitivity to ganciclovir treatment. This causes long-term damage to the liver, which allows transplantation of hepatocytes and the formation of regenerative nodules in the liver of recipient mice [14].

The liver has the ability to regenerate after injury with a wide range of variability in response from person to person. Existing computational models of liver regeneration are largely based on data from experimental animals, and therefore it is not clear how well these models reflect the dynamics of human liver regeneration. B. Verma et al. proposed a mathematical model for calculating the volume of liver resection, taking into account intraoperative factors, metabolic load, and cell death [15].

An interesting study was carried out on a model of liver resection in pigs to study the processes of regeneration. Monitoring of the functional state of the liver and the regeneration occurring in it was carried out using a non-invasive test for determining the maximum functional capacity of the liver (LiMAx). Monitoring of the LiMAx test showed that the results of liver dysfunction correlate with biochemical parameters (bilirubin, AST, ALT, gamma-glutamyl transpeptidase, INR). A catheter in the portal vein allowed monitoring of portal venous pressure. Studies have shown that the LiMAx test can indicate impaired liver function up to 1 day earlier than normal laboratory parameters. The LiMAx test confirmed a significant decrease in liver function on days 1–3 with normalization of parameters 1 week after resection [16].

Ways of regulation of liver regeneration (cytokines, growth factors, metabolic networks)

Cytokines

Immediately after partial hepatectomy, transcription factors activate more than 100 different genes, which are at rest in the intact liver [17]. Interleukin-6 (IL-6) is responsible for the activation of 40% of these genes [18]. It leads to a series of events, including DNA synthesis, cell replication, and an increase in cell size over several days. These early gene responses allow the liver to maintain essential metabolic functions during regeneration. Moreover, it occurs both in hepatocytes and in non-parenchymal liver cells, and hepatocyte replication occurs at an earlier time than in other types of cells.

The initiation of liver regeneration is due to the state of the immune system, the production and release of cytokines. Among them, TNF, NFKB, and IL-6 are important mediators that lead to the activation of STAT3 signaling protein in hepatocytes. After liver resection, TNF binds to the TNF ₁ receptor on non-parenchymal liver cells, and primarily on Kupffer cells. This leads to activation of the intracellular signaling pathway and production of IL-6 [19]. This cytokine acts on hepatocytes through the IL-6 receptor, activating in response the signal transducer and STAT3 activator, as well as extracellular signal kinases 1 and 2 (ERK 1 and 2 pathways) [20, 21]. Numerous studies have shown that this pathway is associated with the onset of liver regeneration. Additional anti-TNF antibodies after hepatectomy inhibit IL-6 production and DNA replication in a rat model [22]. In mice inhibited by IL-6, liver regeneration is delayed [23]. However, hepatocyte proliferation and gene expression can be corrected in this model with a single preoperative injection of Il-6.

Innate immunity plays a special role in the initiation of the cytokinase cascade. Thus, lipopolysaccharide (LPS), C3a and C5a, all components of innate immunity, bind to their respective receptors on Kupffer cells, causing liver regeneration [24]. It has been proven that in rats with limited LPS production, liver regeneration is delayed. J. Campbell et al. investigated immune-mediated signaling pathways involved in the initiation of liver regeneration [25]. They evaluated mice lacking the toll-like receptor (TLR2), LPS co-receptor Cd14, and Myd88 (an adapter protein for the TLR family of proteins). The scientists determined that in Myd88-deficient mice, mRNA, IL-6, and TNF levels decreased after liver resection. Activation of STAT3 and STAT3-sensitive genes in hepatocytes was also blocked. However, none of the operated mice had a delay in DNA replication. The authors concluded that the LPS receptor, Cd14, and TLR2 do not play a significant role in the regulation of cytokine production or DNA replication, but Myd88-dependent pathways are involved in the production of TNF and IL-6 [26]. As for the role of the compliment in initiating liver regeneration in C3a and C5a deficient mice, significant regeneration defects were found after liver resection [27]. At the same time, a decrease in the activation of the cytokine pathway, a decrease in the levels of TNF and IL-6, as well as a decrease in the activity of NF-B and STAT3 were observed. It has been noted that IL-6 performs many functions during liver regeneration, including participation in the acute phase reaction, hepatoprotection, and mitogenic stimulation [21].

Th32 cells are known to regulate immunity against pathogenic invasion, including protection against chronic hepatitis B. The relationship between drug-induced liver injury (DILI) and Th32/Th27 cells was investigated in rats. At the same time, the levels of peripheral Th32/Th27 cells and intrahepatic production of IL-22/IL-17 were studied. A significant increase in Th32 cells and their associated cytokine levels was observed in DILI with a type of hepatocellular injury. A positive correlation was found between the level of intrahepatic IL-22 and liver regeneration. DILI showed increased IL-22 secreting cells, both peripheral and intrahepatic. Th32 and its associated cytokines may be hepatoprotective, which may provide a new perspective for understanding the immunopathogenesis of DILI. Plasma IL-22 may be a reliable indicator for assessing the prognosis of DILI and provide a new therapeutic target for the treatment of DILI [28].

Growth factors

Hepatocytes progress through the cell cycle through mitogenic signals in the form of contacts between cells and various compounds called growth factors. In the liver, these growth factors block the G1 restriction point, allowing hepatocytes to enter S phase.

The epidermal growth factor (EGF) receptor and hepatocyte growth factor (HGF) family of ligands are important in the regeneration process [29]. HGF is produced by stellate cells and acts on hepatocytes in paracrine and endocrine ways.

Some studies show that when liver tissue is damaged, pro-HGF (a biologically inactive precursor protein consisting of a single amino acid sequence) is activated in the extracellular matrix, turning into a biologically active form of HGF. HGF signaling leads to ERK1 activation [30]. Previously it was proved that Kupffer cells have a stimulating effect on the regeneration of liver tissue, enhancing the synthesis of HGF. In addition, increased HGF synthesis leads to an increase in the number of oval liver cells that promote hepatocyte differentiation. Other researchers suggest that the HGF synthesis pathway is important in hepatoprotection due to the activation of the signaling pathway, the main components of which are the enzymes phosphoinositide 3-kinase (PI3K) and AKT kinases [31]. This pathway is responsible for growth, apoptosis, cell proliferation and metabolism.

The EGF receptor family of ligands includes EGF, TGFα, heparin-binding EGF-like growth factor (HBEGF), and amphiregulin (AR). These different ligands have different but often overlapping functions. Thus, EGF is produced by Brunner’s gland in the duodenum [32]. TGFα is produced by hepatocytes in response to cell proliferation and functions autocrine [33]. An increase in the level of TGFα leads to the proliferation of hepatocytes [34]. Models with TGFα inhibition show good liver regeneration after liver resection. All this emphasizes the role of crossed ligands [35].

HBEGF is expressed early in liver regeneration. The HBEGF inhibition model leads to delayed liver regeneration with earlier expression of TGFα as a compensatory mechanism [36].

The effect of portal blood arterialization on the expression of TNFα, HGF and TGFβ ₁ during liver regeneration was studied in an experiment. At the same time, it was proved that promoter effects on portal vein arterialization at an early stage of liver regeneration are associated with changes in the expression of TNFα, HGF and TGFβ ₁ [37].

Auxiliary mitogens include TNF, IL-6, norepinephrine, insulin, bile acids, serotonin, leptin, estrogens, and FGF [38]. Models with inhibition of these mitogens will delay but not stop liver regeneration. It has been shown that serotonin isolated from platelets provides liver regeneration. The expression of 5-HT2A and -2B serotonin receptors increases in the liver after liver resection. M. Lesurtel et al. in a series of experiments on mice showed that thrombocytopenia leads to an inability to induce hepatocyte proliferation, and the administration of a serotonin agonist in mice with thrombocytopenia leads to normal hepatocyte proliferation, while the administration of a serotonin receptor antagonist causes inhibition of regeneration [39].

The role of the spleen in liver regeneration is discussed in the literature. In the experiment it was shown that after splenectomy there is an improvement in liver regeneration. In the group of animals after liver resection and splenectomy, a progressive increase in the number of nuclear antigen-positive proliferating cells was noted, which indicated higher liver regeneration, and the lowest enzymatic activity compared to the group of animals that underwent liver resection without splenectomy. Splenectomy after liver resection resulted in an increase in serum growth factor (HGF) concentrations and a decrease in the level of TGFβ ₁ in the portal vein. In addition, in the group of rats that underwent splenectomy, a decrease in the concentration of not only TGFβ ₁ , but also its TGFβ-RII receptor was recorded, while activation of HGF and its c-Met receptor in the liver occurred. Therefore, removal of the spleen improves liver regeneration [40].

Metabolic pathways

After resection, a large metabolic failure was noted during liver regeneration. At the same time, the liver must maintain the energy requirement necessary for DNA replication and cell division. Amino acids are known to regulate hepatocyte proliferation by modulating the expression of cyclin D1. A study in rats showed that amino acid administration leads to hepatocyte replication, while protein restriction impairs regeneration [41].

MicroRNA is a relatively new type of gene expression regulation. G. Song et al. showed the importance of miRNA in the regulation of hepatocyte proliferation during liver regeneration [42]: in mice with gene inactivation, miRNA treatment showed a delay in cell cycle progression from G1 to S phase. in hepatocytes after liver resection. Most recent works are aimed at studying the use of miRNA in clinical practice in liver diseases [43, 44].

The study of the biological functions of long non-coding RNA (lncRNA) showed that metastasis associated with transcript 1 of lung adenocarcinoma 1 (MALAT1) regulates not only oncogenesis in hepatocellular carcinoma, but also liver regeneration. Functions of lncRNA (MALAT1) were studied in a ² / ₃ partial hepatectomy model in mice. It is noted that MALAT1 was activated during liver regeneration. Moreover, it accelerated hepatocyte proliferation by stimulating cell cycle progression from G1 to S phase and inhibiting apoptosis in vitro . Studies have also shown that MALAT1 is regulated by p 53 during liver regeneration and that p 53 may be a key upstream regulator of MALAT1 activity. In general, the results of the study indicate that MALAT1 is an indicator of liver regeneration. In this regard, pharmacological interventions aimed at MALAT1 may be therapeutically useful in liver failure or liver transplantation, promoting liver regeneration [45].

The so-called rapid growth response gene (EGR-1), which is rapidly induced in response to liver resection, plays a special role in liver regeneration. Mice infected with an adenovirus that expressed EGR-1 underwent liver resection. Cell proliferation and signal transduction pathways from geranylgeranyl diphosphate synthase (GGPPS) to RAS/MAPK were studied in a model of regenerating liver cells, and transaminase activity in blood serum was assessed. Loss of EGR-1 function significantly inhibited liver repair and expression of cyclin D1, cyclin E, and proliferating cell nuclear antigen (PCNA). In addition, loss of EGR-1 function exacerbates liver damage with elevated serum AST and ALT levels. This suggests that EGR-1 stimulated GGPPS plays a vital role in liver regeneration [46].

Scientists have proven that passage through the cell cycle depends on calcium signaling. Thus, EGF and HGF cause signaling through the MAPK–ERK axis, which leads to phosphorylation and activation of a number of factors that promote cell division, including the MYC, FOS, and JUN genes. Calcium signals are important mediators of EGF and HGF signaling. The first results were obtained in experiments on isolated rat hepatocytes. At the same time, a short-term increase in the level of intracellular calcium was found after exposure to EGF or HGF [47].

Transcriptome analysis in mice after liver resection revealed the epigenetic regulator UHRF1, which is required for DNA methylation, as being dynamically expressed during liver regeneration. Deletion of UHRF1 in hepatocytes (Uhrf1HepKO) caused DNA hypomethylation throughout the genome, but, surprisingly, had no measurable effect on gene expression, transposons, or liver homeostasis. Partial hepatectomy of Uhrf1HepKO resulted in early and sustained activation of proregenerative genes and enhanced liver regeneration [48].

The role of cytochrome P450 (CYP) in liver regeneration was evaluated. To do this, a model of liver damage was created in mice by adding 3,5-diethoxycarbonyl-1,4 dihydrocollidine (DDS) to their diet. A 70% liver resection was then performed and liver gene expression patterns measured during regeneration were analyzed. Mice with DDS-induced liver injury expressed the oval cell markers cytokeratin 19 (CK 19) and the epithelial cell adhesion molecule (EpCAM). Partial hepatectomy increased the expression of CYP2R1 and CYP2R2, as well as the alpha-fetoprotein tumor marker, which indicated their importance in the differentiation of oval cells in damaged liver into hepatoblast-like cells [49].

Discussions continue among researchers about the regulatory mechanisms of liver regeneration. So, for example, the answer to the following question has not been found: why, in acute injury, temporary activation of liver stellate cells and sinusoidal cells promotes regeneration, while their long-term activation causes liver fibrosis in chronic injury?

In a murine carbon tetrachloride liver injury model, injured hepatocytes were observed to rapidly express semaphorin 3E (Sema3e), which caused sinusoidal endothelial cell contraction and thereby promoted hepatic stellate cell activation and wound healing. In addition, ectopic and sequential expression of Sema3e in hepatocytes by tail vein hydrodynamic injection resulted in disorganized sinusoidal regeneration and sustained activation of hepatic stellate cells. In contrast, hepatic fibrosis was increased in Sema3e-damaged mice compared to wild-type mice in a chronic liver injury model.

Thus, in the last decade there have been significant advances in understanding the process of liver regeneration. Models have been created that make it possible to study the mechanisms, ways of regeneration, as well as the factors of its regulation. Nevertheless, the issues that are covered in this review remain unresolved.

The authors declare no conflict of interest.

Screening for autoimmune liver damage – advanced, find out the prices for a set of tests and take it in Moscow

In what cases is the test “Screening for autoimmune liver damage – advanced” performed:

• for the diagnosis of autoimmune liver diseases;
• for the differential diagnosis of autoimmune hepatitis, infectious, toxic and hereditary liver diseases.

Synonyms: Advanced screening for autoimmune liver disease. Autoimmune liver damage: extended screening.

Profile composition:

No. 1267 Antinuclear factor (ANF, HEp-2, titers. Antinuclear antibodies by indirect immunofluorescence on HEp-2 cell preparations; ANA IF, titers)

No. 804 Mitochondrial antibodies, IgG + A + M (Mitochondrial Antibo dies , AMA, IgG+A+M)

No. 806 Antibodies to smooth muscles, IgG+A+M (Smooth Muscle Antibodies, SMA, ASMA, IgG+A+M)

No. 819 Antibodies to liver and kidney microsomes, total IgA+IgG+IgM (anti-liver kidney microsomal antibody, anti-LKM, IgG+IgM+ IgA)

No. 1288 Panel of autoantibodies in autoimmune liver diseases (immunoblot) – AMA-M2, M2-3E, SP100, PML, GP210, LKM-1, LC-1, SLA/LP, SSA/RO-52

No. 1289 Antibodies to asialoglycoprotein receptor

No. 47 Immunoglobulins class G (IgG)

No. 46 Immunoglobulins class M (IgM)

Brief description of the study “Screening for autoimmune liver disease – advanced”

Autoimmune hepatitis s (AIH) – chronic progressive liver disease of unknown etiology characterized by the presence of typical autoantibodies in the blood and an increase in the level of immunoglobulins. The pathogenesis of AIH is thought to be related to a loss of tolerance to hepatic antigens and an underlying genetic predisposition. AIH can be asymptomatic or present in various forms (from subclinical to acute liver failure and end-stage liver disease). Autoimmune liver disease should be suspected in every patient in the absence of serological markers of viral hepatitis and clinical symptoms that are not characteristic of the usual manifestations of viral hepatitis. Diagnosis of AIH can only be made after exclusion of viral hepatitis, cholestatic autoimmune liver diseases, Wilson-Konovalov disease, hemochromatosis, α1-antitrypsin deficiency, toxic forms of hepatitis (alcoholic and drug-induced). Differentiating autoimmune hepatitis from other liver diseases is important in terms of the choice of therapy. Diagnosis is based on the identification of relevant histological abnormalities, as well as on characteristic clinical and laboratory signs (among the latter, a high level of immunoglobulins, the presence of one or more specific autoantibodies).

Depending on the detected autoantibodies, the disease is divided into two types: AIH type 1 (AIH-1) is a common AIH (about 90% of cases), manifests at any age, but most of the patients are young women, about a quarter are older people 60 years. The disease is characterized by the presence of antinuclear antibodies (ANA) and/or smooth muscle antibodies (SMA), as well as hypergammaglobulinemia. Patients with this type of AIH respond well to combined and steroid therapy, which allows for a stable remission in 20% of patients after its withdrawal. Type 2 AIH (AIH-2) accounts for about 10% of AIH cases. It usually starts in childhood and adolescence. It is characterized by the presence of type 1 antibodies to microsomal cells of the liver and kidneys (anti-LKM-1) or antibodies to the liver cytosol type 1 (anti-LC-1). Some authors distinguish AIH type 3 (AIH-3): SLA/LP-positive, otherwise similar to AIH-1, but with a more severe course.

AIH is often associated with other autoimmune diseases such as autoimmune thyroiditis, rheumatoid arthritis, celiac disease, ulcerative colitis, systemic lupus erythematosus, etc. Spectrum of clinical manifestations of AIH is diverse: from the absence of obvious symptoms of liver damage to a severe form, almost identical to acute or fulminant viral hepatitis. Often, the clinical manifestation of the disease is characterized by a blurred onset or absence of symptoms, or the presence of one or more non-specific manifestations: fatigue, pain in the right upper quadrant of the abdomen, drowsiness, malaise, anorexia, weight loss, nausea, rash, recurrent jaundice and polyarthralgia of small joints without arthritis. Sometimes patients remember that similar symptoms arose several years ago.

Possible acute onset of AIH (about 25% of cases) or sudden exacerbation of previously undiagnosed AIH. Approximately 1/3 of adults and almost 1/2 of children already have cirrhosis of the liver at the time of diagnosis, regardless of the presence of symptoms. This is due to the latent course of the disease and late diagnosis.

Physical examination parameters may be within normal limits. Possible hepatomegaly, sometimes with pain in the right hypochondrium, splenomegaly. When severe cirrhosis develops, signs of chronic liver damage can be found – palmar erythema and spider veins. In the later stages, the clinical picture of portal hypertension dominates. Observed ascites, varicose veins of the esophagus, gastropathy due to portal hypertension, cytopenia due to hypersplenism, hepatic encephalopathy.

Specifics of laboratory diagnosis during the study “Screening for autoimmune liver disease – advanced”

Diagnosis of AIH is usually based on typical manifestations of the disease and the exclusion of other causes of chronic liver disease.

Screening for autoimmune liver disease may be indicated for hepatitis of unspecified etiology (increased bilirubin, transaminase activity, mild to moderate alkaline phosphatase, gamma-glutamyl transpeptidase, elevated serum immunoglobulins, negative serological markers of hepatotropic viruses : HBsAg, HBeAg, anti-HBc IgM, HBV DNA, anti-HCV, HCV RNA, Epstein-Barr virus and cytomegalovirus nucleic acids).

Specific autoantibodies help in determining the type of autoimmune hepatitis. Antinuclear antibodies (ANA) and anti-smooth muscle antibodies (SMA) are the most common serological markers of AIH-1. The study of antinuclear factor (ANF) is the most informative method for the study of antinuclear antibodies. Antibodies to liver and kidney microsomes (liver-kidney microsomal autoantibodies – LKM) are found in the blood serum of patients with acute and chronic liver pathologies. Patients with AIH-2 are characterized by the presence of anti-LKM-1.

The definition of these serological markers of autoimmune hepatitis is included in the current international criteria for this disease. A high titer (greater than 1:80) of any of these markers, in combination with hypergammaglobulinemia, results in a score of 4 out of 7 required for a definitive diagnosis of autoimmune hepatitis (Simplified Criteria Scoring System of the International Autoimmune Hepatitis Study Group, Hennes et al. 2008), see below. tab. 1.

Table 1. Simplified diagnostic criteria for AIH

ULN – upper limit of normal.

Autoimmune hepatitis: ⩾ 7.

Probable autoimmune hepatitis: ⩾ 6.

*Addition of points for each of the antibodies detected (maximum 2 points).

For the differential diagnosis of hepatitis, the study of specific autoantibodies to AMA-M2, M2-3E, Sp100, PML, gp210, LKM-1, LC-1, SLA / LP, SSA / Ro-52 antigens, which serve as additional markers of liver pathologies, is used and are used in the laboratory diagnosis of autoimmune liver diseases – autoimmune hepatitis and primary biliary cirrhosis. An important additional marker of autoimmune hepatitis are antibodies to the asialoglycoprotein receptor (ASGPR), which are detected at the onset of the disease and increase during exacerbation. Primary biliary cirrhosis is characterized by a progressive course and an immune response directed at the biliary ducts. All patients with this disease develop antibodies that react with mitochondria (AMA). Antinuclear factor occurs in 70-90% of patients. In addition, in primary biliary cirrhosis, antibodies to the cytoplasm of neutrophils (ANCA) can often be detected in the blood serum (see test No. 970). Primary sclerosing cholangitis also belongs to autoimmune pathologies and is often combined with nonspecific ulcerative colitis. Perinuclear type antineutrophil antibodies (pANCA see test no. 970) and antinuclear factor occur in 50% of patients.

It should be taken into account that autoantibodies are not pathogenic, i.e. they are not the cause of the disease, but a consequence of the autoimmune process. Their discovery confirms the need for further diagnostic testing. The titer of autoantibodies may change during the course of the disease. In patients who were seronegative at the time of diagnosis, autoantibodies may be detected later. Repeated research allows to detect autoantibodies and make the correct diagnosis.

What is the purpose of the study “Screening for autoimmune liver damage – advanced”

The profile is designed to diagnose autoimmune liver damage.

Research material

Blood serum.

Method of determination

See relevant tests.

Deadlines

See related tests.

Units

See relevant tests.

Reference values ​​

See relevant tests.

Interpretation of results

Interpretation of test results contains information for the attending physician and is not a diagnosis. The information in this section should not be used for self-diagnosis or self-treatment. An accurate diagnosis is made by the doctor, using both the results of this examination and the necessary information from other sources: history, results of other examinations, etc.

Interpretation of the results of the study “Screening for autoimmune liver disease – advanced”

See relevant tests.

Main literature

1. Abdulganieva D. I., Akberova D. R. Clinical picture, diagnosis and treatment of autoimmune hepatitis //Doctor. RU. – 2019. – no. 3. – S. 27-32.
2. Clinical practice guidelines for the diagnosis and treatment of autoimmune hepatitis. – 2013.
3. Matsievich M. V., Bueverov A. O., Petrachenkova M. Yu. Alternative treatment regimens for autoimmune hepatitis: how justified is their choice? // Almanac of Clinical Medicine. – 2018. – T. 46. – No. 5.
4. Mirzoeva AA, Guliyev EI, Mikhailovskaya LV Difficulties in diagnosing autoimmune hepatitis // International Student Scientific Bulletin. – 2021. – no. 2. – S. 61-61.
5. Medical decision support system. Gastroenterology: Clinical treatment protocols / Compiled by: D.S. Bordin, K.A. Nikolskaya, Bakulin I.G. [and etc.]. – M.: GBU “NIIOZMM DZM”, 2021. – 136 p.
6. Autoimmune Hepatitis. Cleveland Clinic.
7. Autoimmune hepatitis.
8. Czaja A. J. Autoimmune hepatitis–approach to diagnosis //Medscape General Medicine. – 2006. – T. 8. – No. 2. – S. 55.
9. Fallatah H. I., Akbar H. O. Autoimmune hepatitis as a unique form of an autoimmune liver disease: immunological aspects and clinical overview // Autoimmune diseases. – 2012.