Pathogenesis of hepatitis C virus-associated glomerulonephritis

Summary: Hepatitis C virus (HCV), in addition to causing both acute and chronic liver disease, may also be associated with several immunologically-mediated syndromes, particularly cryoglobulinaemia and membranoproliferative glomerulonephritis. Although the glomerulonephritis may be a feature of a systemic cryoglobulinaemic syndrome, it may also present as a primary renal disease without evidence of vasculitis or liver disease. Most of these latter patients, however, will have detectable cryoglobulinaemia either at the time of presentation or with continued observation. In this review, we discuss the pathogenesis of the glomerular disease. Most evidence supports the hypothesis that HCV associated glomerular disease results from the deposition of circulating immune complexes that are usually cryoprecipitable and which contain HCV, anti-HCV IgG, and rheumatoid factors. However, HCV antigens have yet to be identified in glomerular biopsies. This has raised the possibility that other pathogenic mechanisms may be involved, including auto-antibodies directed against glomerular antigens and factors related to chronic liver disease. Further studies are necessary to fully elucidate the pathogenesis of this recently recognized disease.     

Interferon-α in combination with ribavirin as initial treatment for hepatitis C virus–associated cryoglobulinemic membranoproliferative glomerulonephritis

Mixed cryoglobulinemia (MC) and glomerulonephritis are the most important extrahepatic manifestations of chronic hepatitis C virus (HCV) infection. In HCV-infected patients with MC, renal involvement worsens the overall prognosis because of a high incidence of infection or cardiovascular disease. The relationship between MC and HCV infection has prompted the use of antiviral therapy. Two patients with chronic HCV infection, type-II MC and membranoproliferative glomerulonephritis (MPGN), presenting as nephrotic syndrome were treated with interferon (IFN)-α (3 MU 3 times per week) and ribavirin (15 mg/kg daily) for 6 months. Laboratory tests included measurement of anti-HCV antibodies, HCV RNA, and HCV genotyping, and characterization of circulating cryoglobulins. A pretreatment renal biopsy was performed, and the histopathologic lesions were scored according to the index of disease activity. Viremia and cryoglobulinemia were suppressed in both patients. However, a complete remission of proteinuria was observed in 1 patient only. The evaluation of the renal biopsy specimens revealed a mild MPGN (activity score: 5/24) in the patient with remission of proteinuria and a severe MPGN (activity score: 15/24) in the patient who maintained a nephrotic-range proteinuria. Although a fully satisfactory treatment is not yet available, we feel that a reasonable therapeutic strategy for HCV-infected patients with MC nephritis could be as follows: (1) antiviral treatment alone for patients with a low-grade kidney involvement, and (2) a short-term course of steroids and cytotoxic drugs followed by antiviral therapy for acute exacerbations and/or rapidly progressive GN. © 2001 by the National Kidney Foundation, Inc.     

Effect of combination therapy (ribavirin and interferon) in HCV-related glomerulopathy.

BACKGROUND: Hepatitis C virus (HCV) is a major cause of acute and chronic hepatitis throughout the world. Several extrahepatic manifestations, including glomerulonephritis, have been reported to be associated with this type of infection. Cryoglobulinaemic and non-cryoglobulinaemic membranoproliferative glomerulonephritis (MPGN) and membranous nephropathy (MN) are the commonest lesions associated with HCV. Results of treatment of these patients with interferon therapy have been disappointing, since relapse of the viraemia and subsequent relapse of the renal disease are major problems. Combination of interferon with ribavirin in patients with chronic liver disease has been shown to increase the rate of sustained response. METHODS: In this work, 20 patients with HCV-associated glomerulopathy were subjected to an in-depth evaluation of their kidney lesions and HCV involvement. Laboratory, histopathological, immunohistochemical, and electron-microscopy techniques were used. The patients received interferon therapy for 12 months; in interferon-resistant subjects, interferon was combined with ribavirin. RESULTS: MPGN was the commonest kidney lesion, being reported in 85% of these cases, followed by MN and mesangioproliferative glomerulonephritis (10 and 5% respectively). Mixed cryoglobulinaemia was encountered in 60% of the cases. Twelve months' anti-viral treatment resulted in aviraemia in 25% of cases, while liver enzymes were normalized in 75%, 24-h proteinuria significantly decreased (from median 4 g to 1.10 g, P=0.001), serum albumin increased (from median 2.50 to 3.55 g/dl, P=0.012), lower viral titres (from median 1.15 to 0.53 mega-Eq/ml, P=0.049), and C3 and C4 concentrations returned to normal. Basal serum creatinine and viral titres were important determinants of response to treatment. CONCLUSION: This study supports the relationship between HCV and glomerulonephritis, especially MPGN, and the use of a combination of interferon and ribavirin in the treatment of selected cases of HCV-related glomerulopathy.     

All-trans-retinoic acid aggravates cryoglobulin-associated membranoproliferative glomerulonephritis in mice.

BACKGROUND: Transgenic (tg) mice overexpressing thymic stromal lymphopoietin (TSLP) develop mixed cryoglobulinaemia with renal disease closely resembling human cryoglobulinaemic membranoproliferative glomerulonephritis (MPGN), as well as systemic inflammation involving lung, liver and skin as a result of cryoglobulin deposits. We assessed the effect of all-trans-retinoic acid (ATRA), a powerful anti-inflammatory agent, on this model of cryoglobulinaemic MPGN. METHODS: Groups of male TSLP tg mice and wild-type controls were treated with either ATRA (20 mg/kg) or vehicle 3 times weekly by intraperitoneal injection for 4 or 8 weeks, when mice were then sacrificed. Routine histology and immunohistochemistry for collagen IV, alpha-smooth muscle actin, Mac-2 and Ki67 were performed. Immunoglobulin levels were measured by enzyme-linked immunosorbent assay. RESULTS: ATRA unexpectedly exacerbated renal injury in TSLP tg mice with increased glomerular extracellular matrix, mesangial cell activation, glomerular cell proliferation, glomerular macrophage influx and immune complex deposition. Systemic injuries involving liver and lung, and the amount of circulating cryoglobulins were all worsened by ATRA treatment. Furthermore, ATRA resulted in increased IgG1 and IgM levels, the main components of the cryoglobulins in TSLP tg mice, and a manifestation of an enhanced Th2 immune response. CONCLUSIONS: ATRA is not protective but instead aggravates cryoglobulinaemic MPGN and its systemic manifestations in TSLP tg mice. We speculate these findings may be due to augmented production of pathogenic immunoglobulins and/or an enhanced systemic Th2 response. Although disappointing, our results also suggest caution in the application of retinoid therapy to human disease based on the largely positive animal data reported to date.     

Absence of hepatitis B and C viruses in pediatric idiopathic membranoproliferative glomerulonephritis

The blood-borne hepatitis viruses, hepatitis B virus (HBV) and hepatitis C virus (HCV), have similar epidemiological features. The association of chronic HBV infection and glomerulonephritis is well established, particularly in children. Recent reports have shown an association between HCV infection and glomerulonephritis in adults. In order to assess the role of these hepatotropic viruses in membranoproliferative glomerulonephritis (MPGN) we screened 34 children with idiopathic MPGN for the presence of HBV and HCV infection using highly sensitive polymerase chain reaction techniques for the detection of HBV DNA and HCV RNA. Also, enzyme-linked immunosorbent assays were used to detect the presence of antibody to hepatitis B surface antigen and antibody to HCV. No evidence of HBV or HCV infection was demonstrated in any of the patients. We conclude that HBV and HCV are not significant causes of idiopathic MPGN in children in the United States.     

Membranoproliferative glomerulonephritis and circulating cryoglobulins

Background

Previous studies on membranoproliferative glomerulonephritis (MPGN) and cryoglobulinemic glomerulopathy (CG) were based upon case series that were performed before hepatitis C virus (HCV) infection was routinely investigated. Therefore, it remains unknown how far HCV contributes to MPGN or CG, and there have only been a few reports about HCV-negative idiopathic MPGN.

Patients and methods

Thirty-five patients with MPGN diagnosed by renal biopsy who underwent examination for HCV infection at our institute between 1990 and 2008 were recruited for this study. Patients with HCV infection at presentation were included, but patients with complications such as underlying lymphoproliferative disorders, autoimmune diseases like lupus nephritis, infection, and liver disease due to hepatitis B virus or alcohol abuse were excluded. A total of 35 patients were enrolled and they were divided into two groups according to the presence/absence of circulating cryoglobulins (cryo). The 23 patients who had cryo-negative and HCV-negative idiopathic MPGN were divided into subgroups with type 1 and type 3 disease.

Results

In the cryo-positive group (n = 9), 7 patients were positive for HCV infection, while 2 patients were negative. In the cryo-negative group (n = 26), 3 patients were positive for HCV infection, while 23 patients were negative (idiopathic MPGN). Compared with the cryo-negative group, the cryo-positive group had several characteristics such as more severe thrombocytopenia, higher serum immunoglobulin (Ig)G and IgM levels, lower levels of hemolytic complement (CH50) and complement component (C)4, predominant IgM staining, and type 1 histology. Patients with cryo-negative and HCV-negative ‘idiopathic’ MPGN showed predominant staining for IgG in both type 1 and type 3 cases, unlike the predominant staining for IgM in the cryo-positive group. Compared with type 3 cases, type 1 cases had a younger age, lower levels of CH50, C3 and C4, and less proteinuria. In the cryo-positive group, 4 patients (44.4 %) died, with death from B cell lymphoma and liver failure in 2 patients each, while 1 patient (8 %) developed end-stage renal failure requiring dialysis. In contrast, all patients in the cryo-negative group remained alive during follow-up, although 4 patients (2 type 1 cases and 2 type 3 cases) required dialysis.

Conclusion

Cryo-positive MPGN shows a close relationship with HCV infection and IgM, resulting in a poor prognosis. Cryo-negative and HCV-negative idiopathic MPGN has a close relationship with IgG staining, and type 1 cases feature characteristics such as a younger age, more severe hypocomplementemia, and less proteinuria than in type 3 cases.     

Nephropathy associated with heroin abuse in Caucasian patients.

BACKGROUND: Renal disease is a complication of heroin addiction. Using renal biopsies in Caucasian patients, we studied the types of nephropathy associated with heroin abuse. METHODS: Nineteen renal biopsies were performed on heroin addicts between January 1993 and December 2001. The indications for renal biopsy included proteinuria with or without renal insufficiency. RESULTS: All 19 patients had serological evidence of hepatitis C virus (HCV) infection, one had hepatitis B virus surface antigen and three were HIV positive. Thirteen patients (68.4%) were found to have membranoproliferative glomerulonephritis (MPGN), 12 with type I and one with type III. Of the remaining patients, two had chronic interstitial nephritis, two had acute proliferative glomerulonephritis, one had amyloidosis and one had granulomatous glomerulonephritis with interstitial nephritis. No apparent decline in the incidence of renal disease was observed. CONCLUSIONS: In this cohort of male Caucasian heroin addicts, HCV-associated MPGN was the most frequent pattern of nephropathy, showing that the nephropathy associated with heroin abuse in Caucasians is not of the focal and segmental glomerulosclerosis type, in contrast to previous reports on African-Americans. This aspect may have important implications for patient management and prognosis.     

Long-term response to peginterferon in hepatitis C virus-associated nephrotic syndrome from focal segmental glomerulosclerosis

Abstract

Hepatitis C virus (HCV) infection is a global public health problem. Chronic HCV infection is an important cause of chronic liver disease. Since the first reported association between HCV and membranoproliferative glomerulonephritis (MPGN) in 1993, HCV has been described with other types of glomerular diseases, although less frequently. Focal segmental glomerulosclerosis (FSGS) is one such glomerular disease that has been rarely reported in association with HCV. Antiviral therapy with interferon and ribavirin has been shown to be beneficial in HCV-associated MPGN. The optimal therapy of HCV-associated FSGS is not currently known. To our knowledge, long-term response to pegylated interferon monotherapy in treatment of HCV-associated FSGS has not been reported. We report an adult patient with HCV-associated FSGS who presented with nephrotic syndrome and renal failure. Treatment with pegylated interferon alfa-2a monotherapy resulted in sustained virological response with a clinical remission of nephrotic syndrome and stabilization of renal function. Patient continued to remain in clinical remission of nephrotic syndrome with stable renal function, 5 years after treatment. We also briefly review the literature on HCV-associated glomerular diseases, particularly HCV-associated FSGS.     

The pathogenesis of membranoproliferative glomerulonephritis in KwaZulu-Natal,South Africa is unrelated to hepatitis C virus infection

Idiopathic membranoproliferative glomerulonephritis (MPGN) is a well-defined clinicopathological entity with a poor prognosis, with 50% of patients progressing to end stage renal disease (ESRD) within 10 years. It was reported in about 36% of adult Black patients with nephrotic syndrome in our center previously [Seedat et al. 1988]. Hepatitis C virus (HCV) infection has been shown to be associated with cryoglobulinemic as well as non-cryoglobulinemic (or idiopathic glomerulonephritis). The aim of this study was to determine whether an association exists between HCV infection and idiopathic MPGN in a population with a relatively high prevalence of MPGN. We studied adult patients referred with glomerular disease over a two-year period, 104 patients had primary glomerulonephritis. All 23 (22%) patients with idiopathic MPGN were enrolled, as well as 32 age-matched patients presenting with other primary glomerular diseases. We examined serum from all 55 patients for evidence of HCV antibodies and HCV RNA. None of the 55 patients showed evidence of HCV infection. Chronic renal failure was present in 82.6% of the patients with idiopathic MPGN and it was advanced in 52,2%, who either were dialysis-requiring at presentation or progressed to ESRD soon thereafter; 30.4% had moderate chronic renal failure, while only 17.4% had normal renal function. HCV infection is not associated with idiopathic MPGN in our patients. Idiopathic MPGN remains an idiopathic disease, possibly with a poor prognosis in our population.     

Membranoproliferative glomerulonephritis associated with low-grade B cell lymphoma presenting in the kidney

Low-grade B cell lymphoma of mucosa-associated tissue type (MALToma) rarely may involve the kidney. Membranoproliferative glomerulonephritis (MPGN) is an uncommon complication of B cell lymphoma and may be related to cryoglobulin and/or immunoglobulin synthesis by a secretory B cell clone. We report 2 patients with the novel renal biopsy findings of coexistent MALToma and MPGN. Both subjects presented with nephrotic proteinuria and renal insufficiency. One patient had a serum M protein (IgG K) but neither individual had any other clinical or serologic evidence of systemic disease, including hematolymphoid malignancy, autoimmune disease, cryoglobulinemia, or hepatitis C viral infection. Both renal biopsies demonstrated MPGN type I with immunoglobulin deposits that in 1 case showed light chain restriction (IgM K). Electron microscopy disclosed corresponding glomerular electron dense deposits in subendothelial locations. Both biopsies also contained atypical interstitial lymphoid infiltrates comprising marginal zone (centro-cyte-like) cells that infiltrated tubules and showed extra-capsular extension. Immunostains demonstrated a predominantly B cell population that lacked expression of CD5 and cycline D1, and gene rearrangement studies confirmed the presence of a monoclonal B cell population in both cases. These findings indicate that low-grade B cell lymphoma in the kidney may be an unexpected finding in patients with nephrotic syndrome related to MPGN. Immunophenotypic and gene rearrangement studies are important ancillary tools for the evaluation of atypical lymphoid infiltrates in kidney biopsies.     

A comprehensive study of the association between hepatitis C virus and glomerulopathy.

BACKGROUND: Hepatitis C virus (HCV)-related infection is commonly associated with a wide range of glomerulonephritides (GN) including membranoproliferative glomerulonephritis (MPGN). The causal link between HCV infection and renal disease has been postulated through the induction of cryoglobulinaemia and secondary GN. However, the detection of viral particles or genomes within the kidneys of HCV-infected patients has proved to be difficult. With that in mind, we have studied a population of Egyptian HCV-positive patients with associated GN in an attempt to detect viral particles, antigens or RNA within their kidneys. METHODS: Fifty patients were found to be HCV positive out of 303 who presented with a glomerulopathy between 1998 and 1999 at the Mansoura Urology and Nephrology Center, Egypt. Comprehensive investigations of these 50 patients were undertaken including an evaluation of their clinical, biochemical, histological, virological and immunological parameters. In addition, their kidney biopsy material was analysed by electron microscopy (EM) to detect viral particles, by immunohistochemistry to detect a viral core antigen and by RT-PCR to detect RNA. This was compared with 50 HCV-negative controls. RESULTS: Positivity for HCV antibodies was higher among patients with GN (38%) compared with healthy blood donors (16%). Genotype 4 was sequenced in 70% of the HCV-positive samples examined. MPGN was the most common type of GN accounting for 54% of patients. Extrarenal manifestations were absent in the majority (80%) of patients even though 54% had cryoglobulinaemia. EM revealed virus-like particles in 50% of biopsies. Immunohistochemistry failed to reveal HCV-related antigens in kidney sections. HCV RNA was detected in the cryoprecipitates in 66% of patients and 22% of frozen renal sections. Control sections were negative. CONCLUSION: Our findings suggest a causal link between HCV and GN based on the observation of virus-like particles as well as viral RNA within the kidney sections of patients with HCV-associated glomerulopathies.     

Minimal-change nephropathy and chronic hepatitis C infection: coincidental or associated?

Sir, Hepatitis C virus (HCV) infection is among the known main causesof glomerulonephritis. Membranoproliferative glomerulonephritisassociated with cryoglobulinaemia is the predominant form inHCV-infected patients. Less common glomerular diseases, i.e.membranoproliferative glomerulonephritis without cryoglobulinaemia,membranous glomerulonephritis, focal segmental glomerular sclerosis,proliferative glomerulonephritis, renal thrombotic microangiopathyassociated with anti-cardiolipin antibodies and fibrillary andimmunotacoid glomerulopathies, have also occurred in these patients.We encountered a patient with chronic     

Effects of pegylated interferon α-2a on hepatitis-C-virus-associated glomerulonephritis

Hepatitis C virus (HCV) infection leads to chronic liver disease, but it has also been associated with extrahepatic manifestations. Membranoproliferative glomerulonephritis (MPGN) is the most common renal disease associated with HCV. Although renal disease related to HCV in adults has been well studied, it has not been well studied in children because it is rare. A recent study found that antiviral therapy was effective for adult patients with HCV-associated MPGN. We report a 9-year-old girl with HCV-associated MPGN. Her HCV genotype was 1b, and her virus load was high. The first renal biopsy showed mesangial proliferation and partial double contours of the basement membrane on light microscopy and immunofluorescence staining with immunoglobulin (Ig) M, IgG, and C3. The patient was successfully treated with pegylated interferon (IFN) α-2a monotherapy. The antiviral therapy was generally well tolerated. After antiviral therapy, a sustained virological response—defined as negative HCV ribonucleic acid (RNA) at least 24 weeks after antiviral treatment—was achieved, the proteinuria disappeared, and the second renal biopsy showed improvement.     

Hepatitis C Virus Infection and de Novo Glomerular Lesions in Renal Allografts

In the present study we examine whether hepatitis C virus (HCV) infection status influences glomerular pathologic findings in renal allografts and its effect on graft outcome. Renal allograft biopsies performed between January 1991 and June 1999 were considered. Exclusion criteria were insufficient sample, unknown HCV serological status at time of biopsy and final diagnosis of acute rejection. Light microscopy and immunofluorescence studies were performed on all biopsies. According to a predefined protocol, electron microscopy was carried out. Of 138 eligible renal allograft biopsies, 42 fulfilled at least one exclusion criterion. Of 96 biopsies selected for the study, 44 (45.8%) were from HCV-positive and 52 from HCV-negative recipients. Renal biopsy was performed 74 +/- 55 and 60 +/- 39 months after transplantation in HCV-positive and HCV-negative groups, respectively (p = 0.12). Of 44 HCV-positive biopsies, 20 (45.4%) showed membranoproliferative glomerulonephritis (MPGN) (16 type I and 4 type III). Conversely, in HCV-negative biopsies there were only three cases of MPGN (2 type I and 1 type III). De novo membranous GN (MGN) was diagnosed in 8/44 (18.2%) HCV-positive and in 4/52 (7.7%) HCV-negative cases. The prevalence of chronic transplant glomerulopathy was similar in HCV-positive and HCV-negative groups (11.4% and 11.5%, respectively). The prognosis of de novo GN (either MPGN or MGN) was worse in HCV-positive than in HCV-negative recipients (relative risk 4.89; 95% confidence interval, 1.15-20.69; p = 0.03). By multivariate analysis, HCV-positive serology infection was the only independent predictor of graft loss (relative risk 2.64; 95% confidence interval, 1.35-5.17; p = 0.005). In diagnostic renal allograft biopsies the presence of de novo immune-mediated glomerulonephritis, especially type I MPGN, is strongly associated with HCV infection and results in accelerated loss of the graft.     

Interferon and ribavirin treatment in patients with hepatitis C-associated renal disease and renal insufficiency.

BACKGROUND: Hepatitis C virus (HCV) infection is associated with renal manifestations, such as membranoproliferative glomerulonephritis (MPGN) with or without cryoglobulinaemia, membranous glomerulonephritis (MGN) and focal segmental glomerulosclerosis (FSGS). Standard treatment for HCV is interferon and ribavirin, but in renal insufficiency ribavirin has been contraindicated due to fear of side effects. METHODS: Seven patients, two with cryoglobulinaemia, vasculitic manifestations and glomerulonephritis (GN), four with MPGN and one with FSGS were treated with a combination of interferon and ribavirin. Two patients were given pegylated interferon and ribavirin. All patients had at presentation renal insufficiency, with a glomerular filtration rate (GFR) between 10 and 65 ml/min. One patient had HCV genotype 1, the remainder 2 and 3. Duration of therapy was according to genotype (6-12 months). Ribavirin in plasma was monitored by high-performance liquid chromatography (HPLC) to avoid over-dosing, aiming at a target concentration of 10-15 micromol/l. The main side effect of ribavirin, haemolytic anaemia, was monitored closely with haemoglobin controls. RESULTS: Six of seven patients became HCV-RNA-PCR negative and four of seven have maintained both virological and renal remission. One of seven has maintained virological and partial renal remission. One patient did not tolerate interferon, but is in renal remission with low-dose ribavirin. One vasculitis patient responded with complete remission, but relapsed virologically and had a minor vasculitic flare after 9 months. Only one patient with vasculitis had low-dose immunosuppression in addition to anti-viral therapy. Average daily ribavirin dose was 200-800 mg. Ribavirin-induced anaemia was managed in five of seven patients with low-dose iron and erythropoietin between 4000 and 20 000 IU/week. CONCLUSIONS: Interferon and ribavirin can with reasonable safety be used in HCV-related vasculitis and GN irrespective of renal function.     

Thrombotic microangiopathy associated with cryoglobulinemic membranoproliferative glomerulonephritis and hepatitis C

Cryoglobulinemic membranoproliferative glomerulonephritis (MPGN) and increased incidence of vascular thromboses are complications of hepatitis C virus (HCV) infection. This report describes the clinical, laboratory, and renal biopsy findings in two HCV-positive patients with cryoglobulinemic MPGN and thrombotic microangiopathy (TMA). Testing for circulating antiphospholipid antibodies, which are detected in a significant proportion of patients with HCV, was negative in the one case in which it was done. This article discusses the possible cause of the TMA in these two cases.     

Glomerulonephritis in chronic lymphocytic leukemia and related B-cell lymphomas.

We retrospectively analyzed clinical presentation, immunopathological data and renal outcome in 13 patients with glomerulonephritis (GN) and chronic lymphocytic leukemia (CLL) or related diffuse well-differentiated lymphocytic lymphoma (WDLL) of B-cell lineage. B-cell proliferation and glomerulopathy were simultaneously diagnosed in seven of the 13 patients. Nephrotic syndrome was observed in nine patients. Serum creatinine was elevated (greater than 120 mumol/liter) in 10 patients and exceeded 400 mumol/liter in three patients. A clear cut relationship between GN and hematologic disease could be established in nine cases: five patients had MPGN caused by type I or type II cryoglobulinemia; two had MPGN or mesangial hypertrophy with circulating and deposited noncryoprecipitating monoclonal IgG K and IgM K, respectively; in the two remaining patients, monotypic IgG K glomerular deposits exhibiting fibrillary organization were observed in association with MGN or MPGN, despite the absence of circulating M-component by immunofixation. The pathophysiologic link between glomerular lesions and B-cell proliferation was further evidenced by effectiveness of specific treatment of the malignancy by chlorambucil. This drug, used in the absence of steroids, induced complete remission of nephrotic syndrome in the five patients to whom it was given. Moreover, in the five patients with creatininemia greater than 200 mumol/liter who received chemotherapy, substantial improvement in renal function was observed. These overall data demonstrate that the occurrence of GN in B-CLL and related lymphoma is not fortuitous, and testify to the paraneoplastic nature of glomerular involvement mediated by deposition and possibly processing of cryoprecipitating or noncryoprecipitating M-components.     

Type I membranoproliferative glomerulonephritis in an HIV-infected individual without hepatitis C co-infection

Type I membranoproliferative glomerulonephritis (MPGN) is an uncommon manifestation of human immunodeficiency virus (HIV)-associated renal disease in patients co-infected with hepatitis C virus (HCV). We describe a case of Type I MPGN in an HIV-positive diabetic man with nephrotic-range proteinuria and renal insufficiency who was not co-infected with HCV. Tubuloreticular inclusions were present but there was no evidence for either cryoglobulinemia or cryoglobulin deposits in the kidney. This finding suggests that Type I MPGN may represent a reaction of the kidney to HIV independent of the effects of HCV co-infection. Clinical suspicion must be maintained for Type I MPGN in all HIV infected patients presenting with significant proteinuria regardless of HCV infection status.     

Clinicopathologic features of glomerular lesions associated with hepatitis C virus infection in Japan

Background We determined the incidence of hepatitis C virus (HCV)-related glomerulonephritis in Japan and the glomerular localization of HCV-related antigens in this disorder. Methods We analyzed urinalysis findings in 100 consecutive Japanese patients with HCV chronic liver disease from 1993 to 1994. Immunohistochemical analysis using monoclonal or polyclonal antibodies to HCV-core antigen and polyclonal antibodies to HCV-envelope antigen was done on kidney specimens from 11 of 29 patients with antibody to HCV (anti-HCV-Ab). Results Eight of 100 patients had proteinuria, but only 2 cases (2%) were related to HCV nephropathy. Pathohistologic analysis showed 10 patients to have hepatic glomerulosclerosis, and 9 patients had mesangial proliferative glomerulonephritis involving primary immunoglobulin A nephropathy. Membranoproliferative glomerulonephritis was seen in 4 biopsy specimens that showed subendothelial electron-dense deposits and annular structures with characteristic cryogloblin. HCV core antigen was detected along the capillary walls with the same pattern as that of immunoglobulin G deposition and electron-dense deposits in 5 of 6 specimens from patients with both anti-HCV-Ab and HCV ribonucleic acid positive in the sera, but could not be detected in any of 3 specimens, from patients with anti-HCV-Ab but no HCV ribonucleic acid. Envelope antigen was not detected in the glomeruli of any specimens. Conclusions Glomerular lesions associated with HCV infection were characterized by deposition of immune complexes containing HCV core antigen and immunoglobulin G, and by the subendothelial deposition of cryoglobulin. These HCV-related glomerular diseases are rare in Japan (2% incidence), and these lesions should be distinguished from hepatic glomerulosclerosis related to advanced liver disease and other primary glomerular diseases.