Primary glomerulonephritis with detectable glomerular hepatitis B virus antigens

Hepatitis B virus-targeting sodium taurocholate cotransporting polypeptide mediates HBV infection and damage in human renal podocytes

Hepatitis B virus (HBV) may directly infect human podocytes (HPCs). However, the mechanism of direct infection is unclear. We found that HPCs express sodium taurocholate cotransporting polypeptide (NTCP), a specific receptor for HBV entry into hepatocytes. Thus, we investigated whether NTCP mediates HBV infection and damage in HPCs and further clarified the specific mechanism. We constructed shRNA-NTCP1,2, shRNA-NC, WT-NTCP, and MUT-NTCP and transfected them into HPCs. HPCs were infected with HBV, and HBV infection markers were detected by enzyme-linked immunosorbent assay (ELISA) and real-time quantitative PCR (RT-qPCR). The functional changes in HPCs were detected by Transwell migration and scratch assays, apoptosis was evaluated by flow cytometry (FCM), and podocytoskeletal proteins (nephrin, CD2AP, and synaptopodin) were determined by western blotting (WB). Compared with the control HPCs, HPCs infected with HBV showed increased levels of HBV infection markers and apoptosis along with decreased podocytoskeletal protein expressions, cell vitality, proliferation, and migration. Compared with the HPCs infected with HBV, the HPCs transfected with HBV + shRNA-NTCP, and HBV + MUT-NTCP showed decreased levels of HBV infection markers and apoptosis along with increased podocytoskeletal protein expressions, cell vitality, proliferation, and migration; the opposite effects were observed in the HPCs transfected with HBV + WT-NTCP. Overall, the changes to NTCP affected the susceptibility of HPCs to HBV and modulated HPC damage and repair. NTCP can mediate direct HBV infection and damage human podocytes, and the NTCP 157-165 locus is the main site of HBV entry. The findings provide a new target and theoretical basis for HBV-associated glomerulonephritis.

IMPORTANCE

This study identified for the first time that sodium taurocholate cotransporting polypeptide (NTCP) can mediate HBV direct infection and damage to human podocytes, and the NTCP157-165 locus is the main HBV entry site. The findings provide theoretical support for the pathogenesis of direct infection of HBV with kidney tissue. The findings provide a new target and theoretical basis for the treatment of HBV-related glomerulonephritis (HBV-GN). Blocking NTCP is a new target for the treatment of HBV-GN. We found that tacrolimus, a calcineurin inhibitor that blocks NTCP, can effectively treat HBV-GN. This study also provides a theoretical basis for the effective and safe treatment of immunosuppressant tacrolimus for HBV-GN.

Hepatitis B–Associated Lupus-Like Glomerulonephritis Successfully Treated With Antiretroviral Drugs and Prednisone: A Case Report and Literature Review

Kidney involvement with hepatitis B virus is varied and mostly limited to nephrotic syndrome with membranous nephropathy and nephritic syndrome with membranous proliferative glomerulonephritis. Lupus nephritis is associated with nephritic or nephrotic range proteinuria with most common finding of sub-endothelial electron-dense deposits and immunological stain demonstrating full-house picture with all immunological marker staining. Our case discusses a young male patient presenting with rapidly worsening renal function along with proteinuria, found to be positive for both hepatitis B core antibody along with hepatitis B surface antibody plus positive anti-neutrophilic antibody but negative anti-double-stranded DNA. Kidney biopsy demonstrated hepatitis B–associated lupus-like glomerulonephritis. He responded successfully with antiretroviral therapy and high-dose prednisone. Patient did not need lupus-specific treatment and recovered with antiretroviral therapy only. Hepatitis B–associated lupus-like glomerulonephritis has rarely been reported and possess a diagnostic and therapeutic challenge to all nephrologists.

How Times Have Changed! A Cornucopia of Antigens for Membranous Nephropathy

The identification of the major target antigen phospholipase A2 receptor (PLA2R) in the majority of primary (idiopathic) cases of membranous nephropathy (MN) has been followed by the rapid identification of numerous minor antigens that appear to define phenotypically distinct forms of disease. This article serves to review all the known antigens that have been shown to localize to subepithelial deposits in MN, as well as the distinctive characteristics associated with each subtype of MN. We will also shed light on the novel proteomic approaches that have allowed identification of the most recent antigens. The paradigm of an antigen normally expressed on the podocyte cell surface leading to in-situ immune complex formation, complement activation, and subsequent podocyte injury will be discussed and challenged in light of the current repertoire of multiple MN antigens. Since disease phenotypes associated with each individual target antigens can often blur the distinction between primary and secondary disease, we encourage the use of antigen-based classification of membranous nephropathy.

Clinicopathological features, risk factors, and outcomes of immunoglobulin A nephropathy associated with hepatitis B virus infection

BACKGROUND

Hepatitis B virus (HBV) infections are associated with an increased risk of kidney diseases. However, the effects of HBV infection on the prognosis of immunoglobulin A nephropathy (IgAN) are unclear.

METHODS

A total of 838 patients with biopsy-confirmed IgAN were enrolled in this retrospective cohort study. The patients were categorized into either affected by IgAN and HBV infection (HBsAg-IgAN) or by primary IgAN with no sign of HBV infection (P-IgAN). A 1:1 propensity-score matching was performed between the two groups, followed by a Kaplan-Meier survival analysis, to compare the prognoses, and a Cox regression analysis, to identify factors influencing the HBsAg-IgAN outcomes.

RESULTS

A total of 176 pairs of patients were successfully matched. A significant difference in the systolic blood pressure and urea, serum creatinine, uric acid, and 24-h urine protein levels was observed between the groups. A renal pathological analysis also revealed a significant difference in the mesangial hypercellularity between the groups. During a median follow-up period of 2.4 years, Kaplan-Meier analysis also revealed a significant difference in the renal survival between the groups. Furthermore, multivariate Cox analysis confirmed that HBV infection is an independent risk factor for IgAN progression (hazard ratio [HR] 2.096; 95% confidence interval [CI] 1.091-4.026). Finally, the HBsAg-IgAN patients who received treatment with renin-angiotensin-aldosterone system inhibitors had a better overall prognosis than those who received immunosuppressive therapy and antiviral treatment.

CONCLUSION

Our results indicate that the clinicopathological features and outcomes of patients with IgAN differ significantly between those with and without HBV infection, and that HBV is an independent risk factor for IgAN progression.

Detection of viral antigens in renal tissue of glomerulonephritis patients without serological evidence of hepatitis B virus and hepatitis C virus infection

OBJECTIVES

Glomerulonephritis is an important extrahepatic manifestation of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. HBV and HCV infection may be occult, and they are often overlooked by both patients and doctors. The aim of this study was to assess the importance of HBV and HCV infection in glomerulonephritis patients with undetectable HBV surface antigen (HBsAg) and HCV antibody in serum.

METHODS

The HBsAg, the HBV core antigen (HBcAg), and the HCV antigen were detected using immunohistochemistry in frozen renal tissues of 500 glomerulonephritis patients without serological evidence of HBV and HCV infection. Electron microscopy was used to trace the virus particles, and clinicopathological features were also reviewed.

RESULTS

HBsAg or HBcAg was positive in nine out of 500 cases (9/500, 1.8%). Three cases were HBsAg-positive and another six cases were HBcAg-positive. The HCV antigen was found in eight cases (8/500, 1.6%). There was one case of HBV and HCV co-infection (1/500, 0.2%). Under electron microscopy, virus particles were found in the base membrane and cytoplasm of endotheliocytes in the glomerulus. The most common clinical manifestation was nephrotic syndrome (9/18), followed by nephritic syndrome (7/18). Membranous nephropathy was the most common pathological diagnosis (5/18), followed by mesangioproliferative glomerulonephritis (4/18) and IgA nephropathy (4/18).

CONCLUSIONS

Occult HBV and HCV infection might be implicated in HBV- or HCV-associated glomerulonephritis. More attention should be focused on the underlying cause.

Diagnostic significance of hepatitis B viral antigens in patients with glomerulonephritis-associated hepatitis B virus infection

Hepatitis B viral infection can lead to hepatitis B virus-associated glomerulonephritis, a clinically significant subtype of secondary nephritis. In the present study, we examined the presence of PreS1/S2 antigen in renal tissues by use of immunohistochemistry and investigated the use of PreS1/S2 and 2 HBV serum antigens, HBe-Ag and HBs-Ag, in the diagnosis. We assessed the presence of these 3 antigens in patients with confirmed hepatitis B virus-associated glomerulonephritis (n = 22) and patients without this disease (n = 19). Our results indicate that the combined use of PreS1/S2-Ag and serum HBe-Ag in the diagnosis of hepatitis B virus-associated glomerulonephritis had good positive predictive value (0.89), modest negative predictive value (0.77), and substantial agreement based on Cohen's kappa coefficient (κ = 0.660, P < 0.001). We suggest that our results be considered in the development of more definitive diagnostic criteria for hepatitis B virus-associated glomerulonephritis.

Anti-phospholipase A2 receptor antibody in membranous nephropathy

The M-type phospholipase A2 receptor (PLA2R) is a target autoantigen in adult idiopathic membranous nephropathy (MN), but the prevalence of autoantibodies against PLA2R is unknown among Chinese patients with MN. Here, we measured anti-PLA2R antibody in the serum of 60 patients with idiopathic MN, 20 with lupus-associated MN, 16 with hepatitis B (HBV)-associated MN, and 10 with tumor-associated MN. Among patients with idiopathic MN, 49 (82%) had detectable anti-PLA2R autoantibodies using a Western blot assay; an assay with greater sensitivity detected very low titers of anti-PLA2R in 10 of the remaining 11 patients. Using the standard assay, we detected anti-PLA2R antibody in only 1 patient with lupus, 1 with HBV, and 3 with cancer, producing an overall specificity of 89% in this cohort limited to patients with secondary MN. The enhanced assay detected low titers of anti-PLA2R in only 2 additional samples of HBV-associated MN. In summary, these results suggest that PLA2R is a major target antigen in Chinese idiopathic MN and that detection of anti-PLA2R is a sensitive test for idiopathic MN.

Membranous nephropathy: recent travels and new roads ahead

Insights from experimental studies have been recently translated into substantial advances in understanding the pathogenesis of human membranous nephropathy (MN). These include identification of neutral endopeptidase (NEP) as the target antigen in alloimmune MN resulting from fetomaternal immunization in NEP-deficient mothers, and our demonstration that a high proportion of patients with idiopathic MN (IMN) have circulating antibodies to the M-type phospholipase A2 receptor (PLA2R), a transmembrane protein located on podocytes. Here we highlight the studies that led to these discoveries and our current knowledge about the possible role of anti-PLA2R autoantibodies in the pathogenesis of IMN. Given that the sensitivity and specificity of anti-PLA2R for IMN are >75 and 100%, respectively, we foresee that a widely available assay for anti-PLA2R will prove to be valuable for diagnosing IMN, distinguishing it from secondary MN, and evaluating response to therapy. We suggest reasons why 25% of patients with IMN have tested negative for anti-PLA2R, and propose possible explanations for the presence of complement deposits in IMN despite the fact that immunoglobulin G4 (IgG4), the predominant anti-PLA2R IgG subclass, is incapable of activating the classical complement pathway. Finally, we point out avenues to be explored, including the events that induce production of anti-PLA2R, their ability to cause podocyte injury, the role of complement, and the nature of the antibodies in secondary forms of MN.

Membranous nephropathy associated with gastrointestinal stromal tumour: a case report

Membranous nephropathy (MN) is a common cause of nephrotic syndrome in older adults. The association of MN with neoplasia has been controversial, but several recent studies have shown increase incidence of cancer in patients with MN [1]. We report a case of a 49-year-old male with severe nephrotic syndrome and concomitant jejunal gastrointestinal stromal tumour (GIST). The combination of preoperative Imatinib mesylate chemotherapy and tumour excision was followed by complete resolution of proteinuria within 19 months, without specific treatment for MN. An association between MN and GIST has never previously been reported in the literature.

Infection and glomerulonephritis

Glomerular injury, occurring either as primary glomerular disease or as part of a systemic disease process, is usually a result of immune-mediated mechanisms. The morphologic reaction pattern has a diverse spectrum of appearance, ranging from normal by light microscopy in minimal change disease to crescentic forms of glomerulonephritis, with conspicuous disruption of the normal glomerular morphology. The mechanisms of glomerular immune deposit formation include trapping of circulating antigen-antibody complexes and the in situ formation of immune complexes within the glomerulus. While the majority of postinfectious immune-complex-mediated glomerulonephritides are believed to result from the deposition of circulating antigen-antibody complexes, preformed outside of the kidney and secondarily deposited in the kidney, the notion of forming in situ antigen-antibody complexes to either planted antigens or to integral structural components of the glomerulus, through "cross-reacting" autoimmune reactions, is gaining popularity in a variety of forms of glomerulonephritides. Patients with HIV infection may develop a spectrum of renal pathology, the glomerular manifestations of which include both antigen-antibody complex and nonimmune-complex-mediated pathogenetic mechanisms. Similarly, patients with Streptococcal infections, Hepatitis B virus, or Hepatitis C virus infection may develop a spectrum of glomerulonephritides, which are predominantly immune-complex-mediated. Therapy for glomerular diseases due to HIV, hepatitis B, or C virus infections remains a challenge.

Viral nephropathy

Viral infections can cause many glomerular diseases. The diagnostic criteria for virus-related nephropathy include detailed clinical and laboratory data, and tissue molecular analysis. Several mechanisms are involved in the pathogenesis of virus-related nephropathy, including tropism of the virus in the kidney, induction of abnormal immune complexes, direct cytopathogenic effects, and multiorgan failure. Hepatitis B virus is associated with membranous nephropathy and mesangiocapillary glomerulonephritis in endemic areas. Hepatitis C virus causes various forms of glomerulonephritis, including cryoglobulinemia-mediated glomerulonephritis. Infection with HIV is associated with a collapsing focal segmental glomerulosclerosis, a distinctive disease that affects mainly Africans and African Americans. In the course of HIV infection, other types of immune complex glomerulonephritis can occur, most frequently in whites. Recent reports indicate a role for parvovirus B19 in 'idiopathic' collapsing focal segmental glomerulosclerosis. Both hantaviruses, and coronaviruses associated with severe acute respiratory syndrome, can lead to acute renal failure. Renal biopsy followed by appropriate serological and molecular testing is essential for defining virus-related glomerular lesions and guiding prognostic and therapeutic evaluation.

Lamivudine in hepatitis B-associated membranous nephropathy

BACKGROUND

Although lamivudine is effective for treatment of chronic hepatitis B (HBV) infection, its potential therapeutic impact on HBV-related membranous nephropathy (MN) in adults has not been characterized.

METHODS

We treated 10 HBsAg-positive patients with biopsy-proven MN, elevated serum alanine aminotransferase (ALT), and HBV-DNAemia (group 1), and compared their clinical course with 12 patients diagnosed to have HBV infection, elevated serum ALT, and MN in the pre-lamivudine era (group 2).

RESULTS

Baseline demographic and clinical parameters were not different between the 2 groups. In group 1, lamivudine treatment was associated with significant reduction in proteinuria, increase in serum albumin, normalization of ALT levels, and disappearance of circulating HBV-DNA during the first year. Four (40%) and 6 (60%) patients went into complete remission (proteinuria <0.3 g/d) at 6 and 12 months, respectively. In group 2, significant proteinuria persisted during the first year. One (8.3%) and 3 (25%) patients went into remission. Cumulative 3-year renal survival [using end-stage renal disease (ESRD) as primary end point] was 100% in group 1 and 58% in group 2 (P= 0.024, log rank test). Blood pressure control reached the target of below 130/85 mm Hg in both groups. Lamivudine was well tolerated and not associated with any adverse events. Hepatic decompensation or malignancy was not observed during follow-up in both groups.

CONCLUSION

HBV-related MN leads to ESRD in a significant proportion of patients before the advent of antiviral therapy. Lamivudine treatment improves renal outcome in HBV carriers with MN and evidence of liver disease.

Ultrastructure of kidney cell population in patients with markers of HCV- and HBV-infections (analysis of biopsy specimens)

Changes in the glomerular, tubular, and interstitial compartments were revealed in kidney biopsy specimens from patients with serological markers of HCV and HBV infections. The dominant change was destruction of the tubular apparatus and atrophy of the tubular epithelium associated with progressive interstitial fibrosis. Our results indicate that kidney disorders constitute patho- and morphogenesis of systemic infection in HCV- and HBV-infected patients.

Glomerulonephritis after recombinant hepatitis B vaccine

Renal complications after vaccination with hepatitis B recombinant vaccine are rare; very few cases are reported without a histopathologic definition. We describe a case of glomerulonephritis in a 12-year-old girl, beginning after the inoculation of hepatitis B vaccine. The immunohistochemical examination of her renal biopsy, with the use of monoclonal antibodies, shows the presence of hepatitis B surface antigen in renal tissue. After 2 years chronic glomerulonephritis persisted and was treated with angiotensin-converting enzyme inhibitors. After 3 years of follow-up, the renal disease was in remission, and treatment was stopped.

Membranous glomerulopathy: emphasis on secondary forms and disease variants

Membranous glomerulopathy (MGN) is characterized by subepithelial immune complex deposits and glomerular basement membrane (GBM) thickening. The majority of patients present with nephrotic syndrome and outcomes are variable. Pathologically, deposits at sites other than the subepithelial aspect of the GBM favor the presence of secondary forms of MGN which are seen most commonly in the setting of autoimmune disease, infection, neoplasia, and with certain therapeutic agents. MGN is the most common form of de novo glomerular disease seen in the renal allograft and may be seen concurrently with other forms of glomerular disease including focal segmental glomerulosclerosis, IgA nephropathy, diabetic nephropathy, and anti-TBM nephritis. This review emphasizes the detection of secondary forms and variants of MGN.

Extrahepatic manifestations of chronic viral hepatitis

Hepatitis B (HBV) and C (HCV) viruses are well-recognized causes for chronic hepatitis, cirrhosis, and even for hepatocellular carcinoma. Apart from liver disease, these viral infections are known to be associated with a spectrum of extrahepatic manifestations. The prevalence of clinically significant extrahepatic manifestations is relatively low, but it can be associated with significant morbidity and even mortality. An awareness and recognition of these manifestations is of paramount importance in facilitating early diagnosis and in offering treatment. However, treatments are not necessarily effective, and patients may continue with disabling extrahepatic manifestations. Hepatitis B virus has been well recognized as causing a variety of manifestations that include skin rash, arthritis, arthralgia, glomerulonephritis, polyarteritis nodosa, and papular acrodermatitis. More recently, infection with hepatitis C virus has elicited considerable interest for its role in a spectrum of extrahepatic manifestations. Among the best-reported are cryoglobulinemia, glomerulonephritis, high titer of autoantibodies, idiopathic thrombocytopenic purpura, lichen planus, Mooren's corneal ulcer, Sjögren's syndrome, porphyria cutanea tarda, and necrotizing cutaneous vasculitis. The precise pathogenesis of these extrahepatic complications has not been determined, although the majority represent the clinical expression of autoimmune phenomena.

Hepatitis B virus-related nephropathy and lupus nephritis: morphologic similarities of two clinical entities

We compared the clinicopathologic features of 22 patients with hepatitis B virus-related membranous nephropathy, all with detectable glomerular hepatitis B e antigen, and of 26 patients with lupus nephritis class V. Both groups of patients similarly presented with heavy proteinuria or nephrotic syndrome; however, the patients with hepatitis B virus-related membranous nephropathy, who were predominantly male, did not have the extrarenal manifestations and autoantibodies seen in systemic lupus erythematosus. The glomerular lesions in both clinical entities were similar and at times indistinguishable, demonstrating polyclonal immunoglobulins and polytypic complements in similar subepithelial ultrastructural distribution. No morphologic feature, single or combined, carrying a high positive predictive value for the diagnosis of either nephritis was identified. Lesions such as hematoxyphil bodies and fingerprint dense deposits, distinctive of systemic lupus erythematosus, were rarely found. At the time of biopsy, when systemic lupus erythematosus is not clinically suspected, the diagnosis between hepatitis B virus-related membranous nephropathy and lupus nephritis may be difficult or impossible to differentiate, especially in geographic areas where both lupus nephritis and hepatitis B surface antigen carriers are common. This study focused on the use of specific monoclonal antisera to detect glomerular hepatitis B virus antigens, which contribute to the diagnosis of hepatitis B virus-related nephritis.

Detection of hepatitis B virus DNA and RNA in kidneys of HBV related glomerulonephritis

Glomerular deposition of hepatitis B virus (HBV) antigens are observed in chronic HBsAg carriers with different glomerulonephritides yet the etiologic role of HBV remains uncertain. We examined the paraffin section of kidney biopsies from 40 chronic HBsAg carriers with membranous nephropathy (MGN), mesangiocapillary glomerulonephritis (MCGN) or IgA nephropathy (IgAN) for HBV DNA and HBV RNA using in situ hybridization (ISH). Glomerular HBV antigens were present in all biopsies by immunofluorescence. HBsAg or HBcAg mRNA was also studied in RNA extracted from frozen renal tissue using a two-step polymerase chain reaction (PCR) following reverse transcription (RT). HBcAg DNA was not easily detected with ISH alone, but was readily found in 31 biopsies (78%) following PCR. HBV DNA was detected mainly in the cytoplasm of proximal tubular epithelia but not in glomerular cells. HBsAg and/or HBcAg mRNA were detected by RT-PCR in extracted RNA from 13 biopsies (33%). The PCR findings were further confirmed by (a) Southern blot hybridization using a cloned HBV probe and (b) absence of PCR product following treating RNA with RNase or omitting the RT. It is plausible that HBV DNA in renal tubules represents endocytosis of HBV DNA in the urinary filtrate and the HBV RNA extracted from kidney biopsies could derive from infiltrating cells bearing HBV RNA. Hence, ISH with specific HBV core gene RNA probe was performed subsequently. HBcAg RNA, localized in the nuclei and cytoplasm of glomerular and tubular cells, was detected in 56%, 20%, and 36% of renal biopsies in chronic HBsAg carriers with MGN, MCGN, and IgAN, respectively. Our findings indicate the presence of viral transcription in glomerular cells and renal tubular epithelia, supporting an etiological role of HBV in some chronic HBsAg carriers who develop coexisting glomerulonephritides.