Hepatic immunohistochemical staining with a monoclonal antibody against HCV-E2 to evaluate antiviral therapy and reinfection of liver grafts in hepatitis C viral infection

Immunohistochemical diagnosis of human infectious diseases: a review

BACKGROUND

Immunohistochemistry (IHC) using monoclonal and polyclonal antibodies is a useful diagnostic method for detecting pathogen antigens in fixed tissues, complementing the direct diagnosis of infectious diseases by PCR and culture on fresh tissues. It was first implemented in a seminal publication by Albert Coons in 1941.

MAIN BODY

Of 14,198 publications retrieved from the PubMed, Google, Google Scholar and Science Direct databases up to December 2021, 230 were selected for a review of IHC techniques, protocols and results. The methodological evolutions of IHC and its application to the diagnosis of infectious diseases, more specifically lice-borne diseases, sexually transmitted diseases and skin infections, were critically examined. A total of 59 different pathogens have been detected once in 22 different tissues and organs; and yet non-cultured, fastidious and intracellular pathogens accounted for the vast majority of pathogens detected by IHC. Auto-IHC, incorporating patient serum as the primary antibody, applied to diseased heart valves surgically collected from blood culture-negative endocarditis patients, detected unidentified Gram-positive cocci and microorganisms which were subsequently identified as Coxiella burnetii, Bartonella quintana, Bartonella henselae and Tropheryma whipplei. The application of IHC to ancient tissues dated between the ends of the Ptolemaic period to over 70 years ago, have also contributed to paleomicrobiology diagnoses.

CONCLUSION

IHC plays an important role in diagnostic of infectious diseases in tissue samples. Paleo-auto-IHC derived from auto-IHC, is under development for detecting non-identified pathogens from ancient specimens.

HBME-1 expression in differentiated thyroid carcinoma and its correlation with the ultrasonic manifestation of thyroid

We investigated expression of the protein human bone marrow endothelial cell marker-1 (HBME-1) in differentiated thyroid carcinoma tissues, and analyzed its correlation with ultrasonic manifestation of thyroid. The immunohistochemistry (IHC) staining method was used to measure the expression of HBME-1 in patient with nodular goiter (control group), papillary differentiated thyroid carcinoma (papillary carcinoma group) and follicular differentiated thyroid carcinoma (follicular carcinoma group) to investigate the differences in expression of HBME-1. We further analyzed the correlation of the expression of HBME-1 in the papillary carcinoma group and the follicular carcinoma group with ultrasonic manifestation of thyroid. In both the papillary carcinoma group and the follicular carcinoma group, the levels of HBME-1 in affected tissues and the IHS score of HBME-1 expression were higher than those in the control group (p<0.05). In the papillary carcinoma group, the mean IHS score of HBME-1 expression in affected tissues was higher than in the follicular carcinoma group (p<0.05). There were no statistically significant differences in comparison to HBME-1 expression in affected tissues between the papillary carcinoma group and the follicular carcinoma group (p>0.05). Between the papillary carcinoma group and the follicular carcinoma group, the differences in the comparison of the nodule diameter, echo, shape, boundary, calcification and blood flow signal were statistically significant (p<0.05), but incidence rate of enlargement of cervical lymph nodules between the groups were not statistically significant (p>0.05). Among patients in the papillary carcinoma group, the comparison of the nodule diameter, echo, shape, boundary, calcification and blood flow signal between the HBME-1-positive patients and the HBME-1-negative patients showed no statistical significance (p>0.05), but in the nodules of HBME-1-positive patients, the proportion of blood flow signal was higher than that in the nodules of HBME-1-negative patients. Among patients in the follicular carcinoma group, there was no statistically significant differences in the comparison of ultrasonic manifestation of thyroid (p>0.05). Therefore, there are difference in HBME-1 expression and ultrasonic manifestations of thyroid in patients with papillary carcinoma and follicular differentiated thyroid carcinoma.

Occult HCV Infection: The Current State of Knowledge

Context

Occult HCV infection (OCI) is defined as the presence of HCV-RNA in hepatocytes and the absence of HCV in the serum according to usual tests. We aimed to define OCI and provide information about the currently available diagnostic methods. Then we focus on specific groups that are at high risk of OCI and finally investigate immune responses to OCI and the available treatment approaches.

Evidence Acquisition

PubMed, Scopus and Google Scholar were comprehensively searched with combination of following keywords: “occult”, “hepatitis C virus” and “occult HCV infection”. The definition of OCI, diagnostic methods, specific groups that are at high risk and available treatment approaches were extract from literature. An analysis of available articles on OCI also was done based on Scopus search results.

Results

OCI has been reported in several high-risk groups, especially in hemodialysis patients and subjects with cryptogenic liver disease. Furthermore, some studies have proposed a specific immune response for OCI in comparison with chronic hepatitis C (CHC).

Conclusions

With a clinical history of approximately 11 years, occult HCV infection can be considered an occult type of CHC. Evidences suggest that considering OCI in these high-risk groups seems to be necessary. We suggest that alternative diagnostic tests should be applied and that there is a need for the participation of all countries to determine the epidemiology of this type of HCV infection. Additionally, evaluating OCI in blood transfusion centers and in patients who receive large amounts of blood and clotting factors, such as patients with hemophilia, should be performed in future projects.

Imaging of hepatitis C virus infection in liver grafts after liver transplantation

BACKGROUND & AIMS

The detection of native hepatitis C virus (HCV) antigens in liver tissue may be relevant to diagnostic purposes and to better understand the pathogenesis of HCV infection. The aim of our study was to characterize HCV antigens in liver grafts.

METHODS

We selected 32 liver transplant (LT) recipients with recurrent hepatitis C. HCV core and NS5A antigens were detected in formalin-fixed, paraffin-embedded (FFPE) liver biopsies obtained immediately after graft reperfusion (negative controls), during the acute phase of HCV infection (1-6 months) and during follow-up (7-74 months) after LT. Viral antigens were assessed by immunohistochemistry and confocal microscopy.

RESULTS

All reperfusion biopsies were negative for both antigens. Core protein was detected in 75% and 33% of acute phase and follow-up biopsies, respectively. HCV antigens were not detected in any of the 10 samples from patients who cleared HCV after antiviral treatment. Immunostaining was hepatocellular, with a granular cytoplasmic pattern and a wide spectrum of intensity. We found a significant association between viral load and the presence of HCV core-positive hepatocytes (p=0.004). NS5A colocalized strongly with core (66%) and adipophilin (36%), supporting the localization of core and NS5A around lipid droplets. A detailed three-dimensional analysis showed that NS5A surrounded the core and adipophilin-positive areas.

CONCLUSIONS

HCV antigens can be detected in FFPE liver biopsies by immunohistochemistry. The in vivo colocalization of core and NS5A proteins around the lipid droplets supports that the latter may play a role in virus particle production, similar to what reported in vitro.

Occult infection with hepatitis C virus: friend or foe?

Hepatitis C virus (HCV) infection is a global pandemic associated with a growing disease burden due to cirrhosis and the consequent morbidity and mortality. Transmission is largely via blood-to-blood contact. Following primary infection, a minority of individuals clear the infection predominantly via cellular immune mechanisms, whereas the majority become chronically infected. Recent data suggest that a third outcome may also be possible, termed 'occult' infection in which subjects who are known, or suspected to have previously been infected with HCV, no longer have viral RNA in their serum at levels detectable by sensitive commercial assays, but do have virus detected by ultra-sensitive techniques. Occult infection has also been detected in peripheral blood mononuclear cells, which may indicate an extra-hepatic reservoir of the virus. Although the clinical significance of occult infection remains unknown, most authors have raised concerns of recrudescent infection. Here we critically review the published literature, suggest further avenues of investigation and propose that occult infection may be beneficial to the host by maintaining immunological memory to protect against reinfection.

Quantitation of replication of the HCV genome in human livers with end-stage cirrhosis by strand-specific real-time RT-PCR assays: methods and clinical relevance

HCV replicates in liver via an intermediate negative strand RNA. To study the relevance of HCV genome replication, quantitative strand-specific HCV real-time RT-PCR assays were developed and applied to livers explanted because of end-stage cirrhosis. The assays have broad ranges of determination and a high reproducibility and accuracy. Analysis of five different samples showed an even distribution of HCV genomes in four livers. Hepatic concentrations of positive (PS)- and negative (NS)-strand RNA did correlate with each other, with PS/NS ratios ranging between 3 and 340. Hepatic concentrations of HCV-PS or -NS RNA did not correlate with serum HCV-RNA levels or with genotypes. A high HCV envelope-2 protein expression correlated with a low NS concentration. HCV-PS and -NS levels, E2 protein expression and genotype did not correlate with biochemical tests or with histological changes in the explanted liver, but the ratio NS/PS, a marker of viral replication, correlated with the severity of the recurrent post-transplant hepatitis caused by HCV. This suggests the existence of an extra-hepatic location of HCV with comparable viral replication rate being responsible for the infection of the newly transplanted liver.

Immunohistochemical staining of liver grafts with a monoclonal antibody against HCV-Envelope 2 for recurrent hepatitis C after living donor liver transplantation

AIM

We evaluated the expression of hepatitis C virus (HCV) antigen on liver grafts by immunohistochemical staining (IHS) using IG222 monoclonal antibody (mAb) against HCV-envelope 2 (E2).

METHODS

The study material was 84 liver biopsy specimens obtained from 28 patients who underwent living donor liver transplantation (LDLT) for HCV infection. The biopsy samples were examined histopathologically, and by IHS using IG222 mAb against HCV-E2. Serum HCV-RNA level was measured in all patients. The IHS grades were compared among the three groups classified according to the time elapsed from LDLT (at 1-30, 31-179 and > or =180 days post-LDLT) and among four post-transplant conditions, including acute cellular rejection (ACR).

RESULTS

Immunoreactivity to IG222 was detected in 78.6% of the specimens obtained during the first month after LDLT, and there were no significant differences on the IHS grades between the three groups classified according to the time elapsed from LDLT. The IHS grades were significantly stronger in definite recurrent HCV (n = 12) and probable recurrent HCV (n = 7) than in definite ACR (n = 7) and other complications (n = 8). There were no significant differences in serum HCV-RNA levels among the four post-transplant conditions. There was no significant correlation between the IHS grades using IG222 mAb and serum HCV-RNA levels when data of 84 liver biopsy specimens were analyzed.

CONCLUSIONS

Constant HCV-E2 expression was observed in liver biopsy specimens obtained 1 month or longer. The strong HCV-E2 expression on liver grafts were associated with recurrent hepatitis C after LDLT, but the serum HCV-RNA levels were not.

Immunohistochemical detection of HCV proteins in liver tissue

Detection and localization of HCV in liver tissue are vital for diagnostic purposes and clinical management of HCV-infected patients, as well as for the elucidation of viropathological mechanisms. The fragility of HCV RNA and the low levels of viral expression in infected tissues are a constant limitation in molecular assays for HCV characterization. HCV antigen detection, by immunochemistry, in liver biopsies is an attractive option for precise localization and quantification of viral proteins with direct access to histological patterns. We describe here a study using a novel immunohistochemical method effective on fixed, archived specimens, including liver biopsies and surgical resection samples. The initial protocol uses a biotin-detection system but can also be used in a polymer-detection system. This protocol offers easy, precise, and strong staining resolution with distinct patterns consistent with the liver pathology, irrespective of the viral HCV genotype examined. This approach provides applications for diagnosis as well as for exploratory pathological studies.

HBx or HCV core gene expression in HepG2 human liver cells results in a survival benefit against oxidative stress with possible implications for HCC development

Hepatitis virus replication in the liver is often accompanied by inflammation resulting in the formation of reactive oxygen species (ROS) and nitric oxide (NO) and these may induce cell death. We investigated whether the expression of HBx or HCV core protein in HepG2 cells has an influence on the sensitivity of these cells for oxidative radicals. Our previous study, using the inducible HBV model of HepAD38, revealed that oxidative-stress-related genes are upregulated by virus replication. In the present study, we examined the intracellular pro-oxidant status with dichlorofluorescein (DCF) in HepG2 cell lines transfected with HBx, HbsAg and HCV core. Baseline intracellular oxidative levels were not different in the cell lines expressing viral proteins as compared to control. However, when these cells were exposed to H(2)O(2), the viral protein expressing cells, especially those expressing HBx, showed a reduced level of ROS. This suggests that HBx and HCV core transfected cells can convert H(2)O(2) to less reactive compounds at a higher rate than the control cells. When HBx or HCV core expressing cells were exposed to peroxynitrite (a highly reactive product formed under physiological conditions through interaction of superoxide (O(2)(-)) with NO) these cells were less sensitive to induction of cell death. In addition, these cell lines were less prone to cell death when exposed to H(2)O(2) directly. In conclusion, HBx and HCV core expression in HepG2 cells leads to a survival benefit under oxidative stress which in vivo can be induced during inflammation.

Efficient hepatitis C antigen immunohistological staining in sections of normal, cirrhotic and tumoral liver using a new monoclonal antibody directed against serum-derived HCV E2 glycoproteins

Detection and localization of Hepatitis C Virus (HCV) in liver tissue is useful for diagnostic purposes as well as to elucidate the mechanisms by which the virus participates in hepatocarcinogenesis. However, so far, a sensitive method for HCV detection at the cellular level is lacking. We describe here the application of a novel antibody, D4.12.9, developed against serum-derived HCV RNA-positive particles, for the detection of E2 proteins by immunohistochemistry in fixed, archived specimens including liver biopsies of HCV-infected patients and surgical specimens of hepatocellular carcinoma. We demonstrate that D4.12.9 is a powerful tool for sensitive and specific detection of HCV, independently of viral genotype. This approach has applications to diagnosis as well as exploratory pathological studies.

Hepatitis C virus-replicating hepatocytes induce fibrogenic activation of hepatic stellate cells

BACKGROUND & AIMS

The mechanism by which hepatitis C virus induces liver fibrosis remains largely obscure. To characterize the profibrogenic potential of hepatitis C virus, we used the hepatitis C virus replicon cell line Huh-7 5-15, which stably expresses the nonstructural hepatitis C virus genes NS3 through NS5B, and hepatic stellate cells as fibrogenic effector cells.

METHODS

Rat and human hepatic stellate cells were incubated with conditioned media from replicon cells, and expression of fibrosis-related genes was quantified by using real-time polymerase chain reaction, protein, and functional assays. Transforming growth factor beta1 activity was determined by bioassay.

RESULTS

Hepatitis C virus replicon cells release factors that differentially modulate hepatic stellate cell expression of key genes involved in liver fibrosis in a clearly profibrogenic way, up-regulating procollagen alpha1(I) and procollagen alpha1(III) and down-regulating fibrolytic matrix metalloproteinases. Transforming growth factor beta1 expression and bioactivity were increased severalfold in hepatitis C virus-replicating vs mock-transfected hepatoma cells. However, transforming growth factor beta1 activity was responsible for only 50% of the profibrogenic activity.

CONCLUSIONS

Hepatitis C virus nonstructural genes induce an increased expression of transforming growth factor beta1 and other profibrogenic factors in infected hepatocytes. The direct induction of profibrogenic mediators by hepatitis C virus in infected hepatocytes explains the frequent observation of progressive liver fibrosis despite a low level of inflammation and suggests novel targets for antifibrotic therapies in chronic hepatitis C.

Morphological and biochemical characterization of a human liver in a uPA-SCID mouse chimera

A small animal model harboring a functional human liver cell xenograft would be a useful tool to study human liver cell biology, drug metabolism, and infections with hepatotropic viruses. Here we describe the repopulation, organization, and function of human hepatocytes in a mouse recipient and the infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) of the transplanted cells. Homozygous urokinase plasminogen activator (uPA)-SCID mice underwent transplantation with primary human hepatocytes, and at different times animals were bled and sacrificed to analyze plasma and liver tissue, respectively. The plasma of mice that were successfully transplanted contained albumin and an additional 21 human proteins. Liver histology showed progressive and massive replacement of diseased mouse tissue by human hepatocytes. These cells were accumulating glycogen but appeared otherwise normal and showed no signs of damage or death. They formed functional bile canaliculi that connected to mouse canaliculi. Besides mature hepatocytes, human hepatic progenitor cells that were differentiating into mature hepatocytes could be identified within liver parenchyma. Infection of chimeric mice with HBV or HCV resulted in an active infection that did not alter the liver function and architecture. Electron microscopy showed the presence of viral and subviral structures in HBV infected hepatocytes. In conclusion, human hepatocytes repopulate the uPA(+/+)-SCID mouse liver in a very organized fashion with preservation of normal cell function. The presence of human hepatic progenitor cells in these chimeric animals necessitates a critical review of the observations and conclusions made in experiments with isolated "mature" hepatocytes. Supplementary material for this article can be found on the HEPATOLOGY website (http://www.interscience.wiley.com/jpages/0270-9139/suppmat/index.html).

Immunohistochemical identification of HCV target antigen in paraffin-embedded liver tissue: reproducibility and staining patterns

BACKGROUND

Immunohistochemical staining has been applied successfully to detect hepatitis C virus (HCV) antigen in fresh frozen tissue. In paraffin-embedded tissues, however, minimal trials with conflicting results have been reported.

AIMS

The present study is a trial to evaluate the identification of HCV antigen in paraffin-embedded liver biopsies using the anti-HCV monoclonal antibody (MAb) TORDJI-22.

METHODS

We applied immunohistochemical staining for HCV in 56 paraffin-embedded liver biopsy specimens, 46 from patients seropositive for HCV-RNA and 10 control liver biopsy specimens. The TORDJI-22 MAb was applied in dilution 1:40, with overnight incubation.

RESULTS

Reproducible staining patterns of HCV antigen in tissues were identified among the majority (42/46-91%) of HCV RNA seropositive cases. The staining pattern was cytoplasmic of hepatocytes, with occasional nuclear hue. It is mainly coarse granular with microvesicular pattern. Three staining patterns were identified: A, diffuse or membranous; B, patchy; and C, occasional paranuclear. None of the control samples showed a similar staining pattern.

CONCLUSION

Immunohistochemical identification of HCV antigen is easy to apply in paraffin-embedded liver biopsy specimens when the optimal detection techniques are applied. The staining pattern is reproducible, being mainly coarse granular cytoplasmic. Cross reactivity with hepatitis B virus antigens was not detected.

Recurrent demyelinating myelitis associated with hepatitis C viral infection

We report a 46-year-old-man who developed recurrent myelitis associated with hepatitis C viral (HCV) infection. Spinal cord biopsy showed acute demyelination without evidence of vasculitis. Antibodies to HCV were present in the CSF; HCV RNA was not detected in the CSF. Neither HCV antigens nor RNA were detected in the spinal cord biopsy, whereas they were found in the liver biopsy. Evaluation for other infectious or autoimmune causes was unrevealing. These observations suggest that recurrent myelitis in this patient is etiologically related to HCV infection, possibly via an immune-mediated mechanism. This is the first report of pathologically proven myelitis associated with HCV infection and we suggest that HCV be considered in the differential diagnosis of the transverse myelitis syndrome.

Expression of hepatitis C virus core protein impairs DNA repair in human hepatoma cells

Several studies have documented the important association between hepatitis C virus (HCV) infection and hepatocellular carcinoma. The mechanisms involved are still unknown and could involve viral proteins. We investigated the effect of HCV-core protein on DNA repair after UV-induced DNA damage. Therefore, we developed and characterized stably transfected HepG2 cell lines that express HCV-core protein as demonstrated by immunohistochemistry. These cells were significantly less capable to repair the DNA damage than control cells. This suppression of DNA repair by HCV-core protein renders the cells more sensitive to acquire mutations that in combination with enhanced in vivo cell turnover in the infected liver might increase the likelihood of malignant transformation of HCV-infected cells by other viral factors or upon exposure to environmental factors (food, drugs, smoking, alcohol, etc.). Interestingly, expression of the full-length HCV core did increase the cell doubling time in one of the cell lines we had developed that could not be attributed to an increase in apoptosis or change in telomerase activity in these cells.

Hepatobiliary pathology

PURPOSE OF REVIEW

Liver biopsy continues to be an essential component in the evaluation of many widely prevalent liver diseases, including chronic hepatitis C, fatty liver, and liver tumors. This annual review of publications in hepatobiliary pathology highlights recent pathologic studies that can be applied to the daily practice of interpreting liver biopsy, explant, and postmortem specimens.

RECENT FINDINGS

The problem of the fatty liver was the subject of many studies. In chronic hepatitis C, genotype 3 infection results in moderate to marked fat that is ameliorated with successful antiviral therapy. In nonalcoholic steatohepatitis, in which the metabolic syndrome is often operative, gene microarray analysis showed altered expression of genes involved in insulin sensitivity and maintenance of mitochondrial function. Pathologic changes affecting centrilobular regions were described in the context of heart disease, Budd-Chiari syndrome, and the sinusoidal obstruction syndrome (venoocclusive disease). A mutation in ferroportin 1 produced a form of hemochromatosis with excessive iron in hepatocytes and also in Kupffer cells and macrophages. Immunostains for Hep Par 1 and polyclonal carcinoembryonic antigen remain important cornerstones in the immunohistochemical diagnosis of hepatocellular carcinoma and its distinction from metastatic adenocarcinoma and cholangiocarcinoma.

SUMMARY

This report reviews recent articles addressing hepatobiliary pathology. In the areas of viral and drug hepatitis, fatty liver, hemochromatosis, Wilson disease, several biliary tract disorders, and pathology of liver tumors, the emerging data have important diagnostic applications.

CD81 is required for hepatitis C virus glycoprotein-mediated viral infection

CD81 has been described as a putative receptor for hepatitis C virus (HCV); however, its role in HCV cell entry has not been characterized due to the lack of an efficient cell culture system. We have examined the role of CD81 in HCV glycoprotein-dependent entry by using a recently developed retroviral pseudotyping system. Human immunodeficiency virus (HIV) pseudotypes bearing HCV E1E2 glycoproteins show a restricted tropism for human liver cell lines. Although all of the permissive cell lines express CD81, CD81 expression alone is not sufficient to allow viral entry. CD81 is required for HIV-HCV pseudotype infection since (i) a monoclonal antibody specific for CD81 inhibited infection of susceptible target cells and (ii) silencing of CD81 expression in Huh-7.5 hepatoma cells by small interfering RNAs inhibited HIV-HCV pseudotype infection. Furthermore, expression of CD81 in human liver cells that were previously resistant to infection, HepG2 and HH29, conferred permissivity of HCV pseudotype infection. The characterization of chimeric CD9/CD81 molecules confirmed that the large extracellular loop of CD81 is a determinant for viral entry. These data suggest a functional role for CD81 as a coreceptor for HCV glycoprotein-dependent viral cell entry.