Renal involvement in hepatitis C infection: cryoglobulinemic glomerulonephritis

Acquired Fanconi syndrome in mixed cryoglobulinemia patients: a single-center case series

PURPOSE

Cryoglobulinemia is a pathological condition characterized by the presence of cryoglobulins in the blood, with cryoglobulinemic glomerulonephritis being the most frequent form of renal involvement. Fanconi syndrome presents as a generalized dysfunction of the proximal tubule, characterized by the presence of polyuria, phosphaturia, glycosuria, proteinuria, proximal renal tubular acidosis, and osteomalacia. We aimed to present five cases co-occurring with Fanconi syndrome and cryoglobulinemia.

METHODS

We retrospectively summarized the cases of five patients with Fanconi syndrome and cryoglobulinemia at Peking Union Medical College Hospital from January 2012 to June 2022. The clinical features, diagnosis, treatment, and prognosis were systematically analyzed.

RESULTS

All five patients exhibited typical features of Fanconi syndrome, and cryoglobulinemia was concurrently detected in all cases. These patients also exhibit positive anti-nuclear antibody spectrum and hyperglobulinemia, and IgM constitutes the predominant monoclonal component in cryoglobulins. In addition to supplemental treatment, timely immunosuppressive therapy may potentially benefit the long-term renal prognosis of patients with this condition.

CONCLUSION

Our findings highlight the rare co-occurrence of Fanconi syndrome and cryoglobulinemia in clinical practice. Despite the lack of causal evidence, the coexistence of Fanconi syndrome and tubulointerstitial injury is also noteworthy in patients with cryoglobulinemia, underscoring the importance of thorough evaluation and tailored management in patients presenting with overlapping renal manifestations. Key Points • Patients with mixed cryoglobulinemia can clinically present with tubulointerstitial injury, specifically manifesting as Fanconi syndrome. • In addition to typical symptoms of Fanconi syndrome, these patients also exhibit positive anti-nuclear antibody spectrum and hyperglobulinemia, while IgM constitutes the monoclonal component in cryoglobulins. • Timely immunosuppressive therapy may improve long-term renal prognosis in these patients.

Liver Disease-Associated Glomerulopathies

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infect a significant number of individuals globally and their extra-hepatic manifestations, including glomerular disease, are well established. Additionally, liver disease-associated IgA nephropathy is the leading cause of secondary IgA nephropathy with disease course varying from asymptomatic urinary abnormalities to progressive kidney injury. Herein we provide an updated review on the epidemiology, pathogenesis, clinical manifestations, and treatment of HBV- and HCV-related glomerulonephritis as well as IgA nephropathy in patients with liver disease. The most common HBV-related glomerulonephritis is membranous nephropathy, although membranoproliferative glomerulonephritis and podocytopathies have been described. The best described HCV-related glomerulonephritis is cryoglobulinemic glomerulonephritis occurring in about 30% of patients with mixed cryoglobulinemic vasculitis. The mainstay of treatment for HBV-GN and HCV-GN is antiviral therapy, with significant improvement in outcomes since the emergence of the direct-acting antivirals. However, cases with severe pathology and/or a more aggressive disease trajectory can be offered a course of immunosuppression, commonly anti-CD20 therapy, particularly in the case of cryoglobulinemic glomerulonephritis.

Management of Hepatitis C Virus and Hepatitis B Virus Infection in the Setting of Kidney Disease

Treatment of chronic hepatitis C virus (HCV) and hepatitis B virus (HBV) infection poses unique challenges in patients with kidney disease. Direct-acting antivirals have been a major breakthrough in eradicating HCV infection, and several pangenotypic regimens are available for patients with chronic kidney disease or end-stage kidney disease requiring dialysis with high cure rates and no need for dose adjustment. Direct-acting antiviral therapy alone can treat HCV-associated cryoglobulinemic glomerulonephritis; concurrent antiviral and immunosuppressive therapy is needed for cases of severe, organ-threatening manifestations of cryoglobulinemia. Immunosuppression may be needed for HBV-associated kidney disease (polyarteritis nodosa or membranous nephropathy) when there is evidence of severe immune-mediated injury while weighing the risk of potential viral activation. Most HBV antiviral agents need to be dose-adjusted in patients with chronic kidney disease or end-stage kidney disease requiring dialysis, and drug-drug interactions need to be carefully evaluated in patients with kidney transplants. Considerations for accepting HCV- and HBV-infected donors for kidney transplantation are discussed.

Evidence of a Link between Hepatitis E Virus Exposure and Glomerulonephritis Development

Viruses can trigger glomerulonephritis (GN) development. Hepatitis viruses, especially Hepatitis C virus and Hepatitis B viruses, are examples of the viruses that trigger GN initiation or progression. However, the proof of a correlation between GN and Hepatitis E virus infection is not clear. Some studies confirmed the development of GN during acute or chronic HEV infections, mainly caused by genotype 3. While others reported that there is no relation between HEV exposure and GN development. A recent study showed that a reduced glomerular filtration rate was developed in 16% of acute HEV genotype 1 (HEV-1) infections that returned to normal during recovery. HEV-1 is endemic in Egypt with a high seroprevalence among villagers and pregnant women. There is no available data about a link between HEV and GN in Egypt.

METHODS

GN patients (n = 43) and matched healthy subjects (n = 36) enrolled in Assiut University hospitals were included in this study. Blood samples were screened for hepatotropic pathogens. Tests for HEV markers such as HEV RNA and anti-HEV antibodies (IgM and IgG) were performed. Laboratory parameters were compared in HEV-seropositive and HEV-seronegative GN patients.

RESULTS

Anti-HEV IgG was detected in 26 (60.5%) out of 43 GN patients. HEV seroprevalence was significantly higher in GN than in healthy controls, suggesting that HEV exposure is a risk factor for GN development. None of the GN patients nor the healthy subjects were positive for anti-HEV IgM or HEV RNA. There was no significant difference between seropositive and seronegative GN patients in terms of age, gender, albumin, kidney function profiles, or liver transaminases. However, anti-HEV IgG positive GN patients had higher bilirubin levels than anti-HEV IgG negative GN patients. HEV-seropositive GN patients had a significantly elevated AST level compared to HEV-seropositive healthy subjects.

CONCLUSION

exposure to HEV infection could be complicated by the development of GN.

Similarities, differences, and possible interactions between hepatitis E and hepatitis C viruses: Relevance for research and clinical practice

Hepatitis E virus (HEV) and hepatitis C virus (HCV) are both RNA viruses with a tropism for liver parenchyma but are also capable of extrahepatic manifestations. Hepatitis E is usually a viral acute fecal-oral transmitted and self-limiting disease presenting with malaise, jaundice, nausea and vomiting. Rarely, HEV causes a chronic infection in immunocompromised persons and severe fulminant hepatitis in pregnant women. Parenteral HCV infection is typically asymptomatic for decades until chronic complications, such as cirrhosis and cancer, occur. Despite being two very different viruses in terms of phylogenetic and clinical presentations, HEV and HCV show many similarities regarding possible transmission through organ transplantation and blood transfusion, pathogenesis (production of antinuclear antibodies and cryoglobulins) and response to treatment with some direct-acting antiviral drugs. Although both HEV and HCV are well studied individually, there is a lack of knowledge about coinfection and its consequences. The aim of this review is to analyze current literature by evaluating original articles and case reports and to hypothesize some interactions that can be useful for research and clinical practice.

Hepatitis E in immunocompromised individuals

Hepatitis E virus (HEV) originally identified as a cause of acute icteric hepatitis in developing countries has grown to be a cause of zoonotic viral hepatitis in developed countries such as the United States. While there are eight identified genotypes to date, genotype 1 (HEV1), HEV2, HEV3, HEV4 are the most common to infect humans. HEV1 and HEV2 are most common in developing countries including Latina America, Africa and Asia, and are commonly transmitted through contaminated water supplies leading to regional outbreaks. In contrast HEV3 and HEV4 circulate freely in many mammalian animals and can lead to occasional transmission to humans through fecal contamination or consumption of undercooked meat. The incidence and prevalence of HEV in the United States is undetermined given the absence of FDA approved serological assays and the lack of commercially available testing. In majority of cases, HEV infection is a self-limiting hepatitis requiring only symptomatic treatment. However, this is not the case in immunocompromised individuals, including those that have undergone solid organ or stem cell transplantation. In this subset of patients, chronic infection can be life threatening as hepatic insult can lead to inflammation and fibrosis with subsequent cirrhosis and death. The need for re-transplantation as a result of post-transplant hepatitis is of great concern. In addition, there have been many reported incidents of extrahepatic manifestations, for which the exact mechanisms remain to be elucidated. The cornerstone of treatment in immunocompromised solid organ transplant recipients is reduction of immunosuppressive therapies, while attempting to minimize the risk of organ rejection. Subsequent treatment options include ribavirin, and pegylated interferon alpha in those who have demonstrated ribavirin resistance. Further investigation assessing safety and efficacy of anti-viral therapy is imperative given the rising global health burden. Given this concern, vaccination has been approved in China with other investigations underway throughout the world. In this review we introduce the epidemiology, diagnosis, clinical manifestations, and treatment of HEV, with emphasis on immunocompromised individuals in the United States.

Lack of Evidence for an Association between Previous HEV Genotype-3 Exposure and Glomerulonephritis in General

Among numerous other immune-mediated diseases, glomerulonephritis has also been suspected to be an extrahepatic manifestation of HEV infection. In this prospective study, we tested 108 patients with glomerulonephritis and 108 age- and sex-matched healthy controls at the University Hospital Hamburg Eppendorf, Hamburg, Germany, for anti-HEV IgG (Wantai test) as a marker for previous HEV exposure. A total of 24 patients (22%) tested positive for anti-HEV IgG. Males tended to be more frequently anti-HEV IgG positive (29%) in comparison to females (16%). However, this does not reach statistical significance (p = 0.07). Anti-HEV IgG positive patients were older in comparison to negative patients (mean 53 vs. 45 years, p = 0.05). The kidney function seems to be slightly decreased in anti-HEV IgG positive patients in comparison to and anti-HEV IgG negative patients basing on creatinine (p = 0.04) and glomerular filtration rate (GFR) (p = 0.05). Slightly higher values of bilirubin could be found in IgG positive patients (p = 0.04). Anti-HEV-IgG seropositivity rate (22%) in glomerulonephritis patients, did not differ significantly in comparison to an age- and sex-matched control cohort of healthy blood donors (31/108 positive, 29%). A total of 2/2 patients with membranoproliferative glomerulonephritis (MPGN) tested anti-HEV IgG positive (p = 0.002 in comparison to glomerulonephritis patients with other subtypes). In conclusion, our findings indicate that previous HEV exposure in a region where GT3 is endemic is not associated with glomerulonephritis in general. However, the subgroup of MPGN patients should be investigated in future studies. Furthermore, future studies are needed to investigate whether the observed association between anti-HEV IgG positivity and reduced GFR in glomerulonephritis patients is HEV associated or is an age-related effect.

Model systems for studying extrahepatic pathogenesis of hepatitis E virus. Current knowledge and future directions

Hepatitis E Virus is the most common cause of acute viral hepatitis globally. HEV infection is endemic in developing countries. Also, autochthonous and sporadic cases are reported in developed countries. HEV causes acute and chronic infections. Besides, extrahepatic manifestations including neurological, renal, haematological, acute pancreatitis and complications during pregnancy are associated with HEV infections. The pathogenesis of HEV in the extrahepatic tissues is either due to direct cytopathic effect mediated by the virus replication, or immunological mechanisms caused by an uncontrollable host response. Researchers have used different in vivo and in vitro models to study the pathogenesis of HEV in the extrahepatic tissues and analyse the host immune response against HEV infection. This review highlights the extrahepatic disorders associated with HEV infection. We focused on the in vivo and in vitro models as a tool for elucidating the HEV infection beyond the liver and studying the mechanisms of HEV induced tissue damages.

Hepatitis E Virus Mediates Renal Injury via the Interaction between the Immune Cells and Renal Epithelium

Renal disorders are associated with Hepatitis E virus (HEV) infection. Progression to end-stage renal disease and acute kidney injury are complications associated with HEV infection. The mechanisms by which HEV mediates the glomerular diseases remain unclear. CD10+/CD13+ primary proximal tubular (PT) epithelial cells, isolated from healthy donors, were infected with HEV. Inflammatory markers and kidney injury markers were assessed in the presence or absence of peripheral blood mononuclear cells (PBMCs) isolated from the same donors. HEV replicated efficiently in the PT cells as shown by the increase in HEV load over time and the expression of capsid Ag. In the absence of PBMCs, HEV was not nephrotoxic, with no direct effect on the transcription of chemokines (Cxcl-9, Cxcl-10, and Cxcl-11) nor the kidney injury markers (kidney injury molecule 1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and interleukin 18 (lL-18)). While higher inflammatory responses, upregulation of chemokines and kidney injury markers expression, and signs of nephrotoxicity were recorded in HEV-infected PT cells cocultured with PBMCs. Interestingly, a significantly higher level of IFN-γ was released in the PBMCs-PT coculture compared to PT alone during HEV infection. In conclusion: The crosstalk between immune cells and renal epithelium and the signal axes IFN-γ/chemokines and IL-18 could be the immune-mediated mechanisms of HEV-induced renal disorder.

Direct-acting antiviral therapy improves kidney survival in hepatitis C virus-associated cryoglobulinaemia: the RENALCRYOGLOBULINEMIC study

Background

Direct-acting antiviral agents (DAAs) have shown high rates of sustained virological response in chronic hepatitis C virus (HCV) infection. However, the influence of DAAs on the course of kidney involvement in HCV-associated mixed cryoglobulinaemia (HCV-MC) has been little studied. The aim of this study was to analyse the effects of antiviral treatment on kidney prognosis and evolution in patients diagnosed with HCV-MC.

Methods

The RENALCRYOGLOBULINEMIC study is an observational multicentre cohort study of 139 patients with HCV-MC from 14 Spanish centres. Clinical and laboratory parameters were measured before and after antiviral treatment. Primary endpoints were kidney survival and mortality after HCV-MC diagnosis. Secondary endpoints were clinical, immunological and virological responses after antiviral treatment.

Results

Patients were divided into three groups based on the treatment received: treatment with DAAs (n = 100) treatment with interferon (IFN) and ribavirin (RBV) (n = 24) and no treatment (n = 15). Patients were followed up for a median duration of 138 months (interquartile range 70-251. DAA treatment reduced overall mortality {hazard ratio [HR] 0.12 [95% confidence interval (CI) 0.04-0.40]; P < 0.001} and improved kidney survival [HR 0.10 ( 95% CI 0.04-0.33); P < 0.001].

Conclusions

Results from the RENALCRYOGLOBULINEMIC study indicated that DAA treatment in patients with HCV-MC improves kidney survival and reduces mortality.

Clinical Manifestations, Pathogenesis and Treatment of Hepatitis E Virus Infections

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis throughout the world. Most infections are acute but they can become chronic in immunocompromised patients, such as solid organ transplant patients, patients with hematologic malignancy undergoing chemotherapy and those with a human immunodeficiency virus (HIV) infection. Extra-hepatic manifestations, especially neurological and renal diseases, have also been described. To date, four main genotypes of HEV (HEV1-4) were described. HEV1 and HEV2 only infect humans, while HEV3 and HEV4 can infect both humans and animals, like pigs, wild boar, deer and rabbits. The real epidemiology of HEV has been underestimated because most infections are asymptomatic. This review focuses on the recent advances in our understanding of the pathophysiology of acute HEV infections, including severe hepatitis in patients with pre-existing liver disease and pregnant women. It also examines the mechanisms leading to chronic infection in immunocompromised patients and extra-hepatic manifestations. Acute infections are usually self-limiting and do not require antiviral treatment. Conversely, a chronic HEV infection can be cleared by decreasing the dose of immunosuppressive drugs or by treating with ribavirin for 3 months. Nevertheless, new drugs are needed for those cases in which ribavirin treatment fails.

Hepatitis C virus - related cryoglobulinemic vasculitis with renal involvement current possibilities of diagnostic and treatment

The extrahepatic manifestations of HCV infections, which include mixed cryoglobulinemia (MC), are important for prognosis and determination of the treatment options of these patients. Currently, mixed MC type II is considered as a specific marker of chronic HCV infection. Kidney damage is one of the severe, often determining a prognosis of extrahepatic manifestation of HCV-associated cryoglobulinemic vasculitis. The review discusses the current diagnostic approaches to cryoglobulinemic GN, as well as perspectives for improving antiviral and pathogenetic therapy.

Treatment of hepatitis C virus infection in patients with mixed cryoglobulinemic syndrome and cryoglobulinemic glomerulonephritis

Cryoglobulinemia is a common extrahepatic manifestation of infection with hepatitis C virus (HCV). When signs and symptoms of systemic vasculitis or glomerulonephritis occur in the presence of circulating cryoglobulins, this syndrome is called "mixed cryoglobulinemia syndrome" (MCS). Historically, interferon-based therapies in HCV have been associated with lower rates of viral cure in patients with MCS than in the general HCV-infected population. The advent of direct-acting antiviral therapies have revolutionized the treatment of HCV, dramatically increasing rates of cure. Early studies of first-generation protease inhibitors (telaprevir and boceprevir) in combination with interferon and ribavirin demonstrated HCV cure rates of 67% and complete clinical response rates of vasculitis symptoms in 60% of patients with MCS; however, regimens were poorly tolerated by patients, 22% discontinued treatment early. More recently, all-oral, interferon-free regimens have become available and combination therapies are now being approved for patients with and without renal impairment. Patients with HCV-MCS achieved sustained virologic response in 297 out of 313 patients (95%) treated with direct-acting antiviral therapy, and 85% had a complete or partial clinical response of MCS symptoms. Current direct-acting antiviral therapies are well tolerated in patients with HCV-MCS and only 1.6% discontinued treatment early. Patients with cryoglobulinemic glomerulonephritis also had an excellent cure rate (94%). The majority improved; 17/52 (33%) experienced full remission and 15/52 (29%) experienced partial remission. There were no reports of worsening kidney function in patients treated with direct-acting antiviral therapies. Less than 5% of patients with HCV-MCS treated with IFN-free direct-acting antiviral therapy required immunosuppression. However, patients with severe vasculitis appear to still require concomitant immunosuppression.

The association of hepatitis C infection with the onset of CKD and progression into ESRD

Hepatitis C virus (HCV) infection is not only an important cause of chronic liver disease, but extrahepatic manifestations are common and include chronic kidney disease (CKD). HCV is classically associated with cryoglobulinemic glomerulonephritis in the context of mixed cryoglobulinemia syndrome, but other glomerular diseases also occur and may be significantly under-recognized. HCV may cause glomerular disease by immune complex deposition; however, other potential mechanisms by which HCV promotes CKD include a direct cytopathic effect of the virus on renal tissue, and by its association with accelerated atherosclerosis, insulin resistance, and chronic inflammation. Epidemiologic studies show HCV infection confers an increased risk of incident CKD and accelerates progression of CKD to end-stage renal disease (ESRD) in the general population, as well as subpopulations including diabetic patients, those coinfected with human immunodeficiency virus (HIV), and kidney transplant recipients. Patients with CKD and HCV infection experience inferior clinical outcomes, including poorer quality of life and an increased risk of mortality. Treatment with interferon-based regimens is associated with decreased risk of incident CKD and ESRD, though prior studies are limited by the small number of patients with HCV and CKD who underwent treatment. With the advent of new, well-tolerated direct-acting antiviral combinations that are not cleared by the kidneys, it is possible to treat all genotypes of HCV infection in patients with CKD and ESRD. More data on the effect of direct-acting antivirals on CKD incidence and progression are necessary. However, there is every expectation that with improved access to HCV treatment, the burden of CKD in patients with HCV could significantly decline.

Predictive factors of renal involvement in cryoglobulinaemia: a retrospective study of 153 patients

Background

The course of cryoglobulinaemia varies widely, from asymptomatic patients to severe vasculitis syndrome. Renal involvement (RI) is the major prognostic factor, and frequently occurs several years after diagnosis. However, predictive factors for RI are not well known. The aim of our study was to identify RI predictive factors during cryoglobulinaemia.

Methods

We retrospectively reviewed the clinical charts of a consecutive series of 153 patients positive for cryoglobulinaemia in the University Hospital of Lyon (France). RI was defined either histologically or biologically if cryoglobulinaemia was the only possible cause of nephropathy.

Results

Among the 153 positive patients (mean age 55 years, 37% male), cryoglobulinaemia was associated with RI in 45 (29%) patients. Sixty-five percent of patients had Type II cryoglobulinaemia, 28% had Type III and 7% had Type I. Autoimmune diseases were the most common aetiology (48%), followed by infectious diseases (18%) and lymphoproliferative disorders (13%). Membranoproliferative glomerulonephritis was the main histological pattern (93% of the 14 histological analyses). A multivariable logistic regression showed that Type II cryoglobulinaemia, a high serum cryoglobulin concentration, the presence of an IgG kappa monoclonal component and diabetes were independently associated with the risk for developing RI.

Conclusion

We identified several factors predictive of RI in patients with cryoglobulinaemia, which were different from the diagnostic criteria for cryoglobulinaemic vasculitis. This could suggest a specific pathophysiology for RI. We suggest performing an extensive renal monitoring and ensure nephroprotection when a diagnosis of cryoglobulinaemia is made in patients with these predictive factors.

Autoimmune Kidney Diseases Associated with Chronic Viral Infections

Autoimmune kidney diseases triggered by viruses are an important cause of kidney disease in patients affected by chronic viral infection. Hepatitis B virus (HBV) infection is associated with membranous nephropathy and polyarteritis nodosa. Hepatitis C virus (HCV) infection is a major cause of cryoglobulinemic glomerulonephritis. Patients with human immunodeficiency virus (HIV) may develop HIV-associated nephropathy, a form of collapsing focal segmental glomerulosclerosis, or various forms of immune-complex-mediated kidney diseases. This article summarizes what is known about the pathogenesis, diagnosis, and management of immune-mediated kidney diseases in adults with chronic HBV, HCV, and HIV infections.

Monoclonal Gammopathy of Renal Significance Presenting as Cryoglobulinemic Glomerulonephritis: A Case Report and Review of Literature

Monoclonal gammopathy of renal significance (MGRS) can present with myriad of morphological features. We report a case of MGRS in a 46-year-old man who presented with nephrotic-range proteinuria and renal insufficiency. Renal biopsy showed amorphous eosinophilic periodic acid–Schiff positive deposits in capillary loops and lamda light chain positivity on immunofluorescence, suggestive of cyoglobulinemic glomerulonephritis. Serum cryoglobulins were positive. Serum immunoelectrophoresis and immunofixation showed a M band of 0.5 g/dl of IgG lambda type. Bone marrow showed 8% of plasma cells which confirmed the diagnosis of MGRS.

Immunosuppressive and antiviral treatment of hepatitis C virus-associated glomerular disease: A long-term follow-up

BACKGROUND

The evidence in the medical literature on the treatment of hepatitis C virus-associated glomerular disease is extremely limited. The advent of nonconventional immunosuppressive agents and direct-acting antivirals promises high efficacy and safety.

AIMS

We conducted an open-label, single-arm clinical study to examine the efficacy and safety of a combined approach for hepatitis C virus-associated glomerular disease.

METHODS

In the first phase of the study, patients with hepatitis C virus-associated glomerular disease received interferon-based antiviral therapy and immunosuppressive agents; since 2013, interferon-free antiviral therapy was adopted and novel immunosuppressants (including B-cell depleting agents and mycophenolate mofetil) or immunomodulators (ribavirin) were choiced. Virological and clinical responses were evaluated over a long observation period (median follow-up of 60 weeks and 46.5 months after the end of treatment with interferon and direct-acting antiviral agents, respectively).

RESULTS

We enrolled 25 consecutive patients with hepatitis C virus-associated glomerular disease, 8 being liver transplant recipients for hepatitis C. A total of 13 patients received therapy with direct-acting antivirals and experienced sustained viral response (serum hepatitis C virus RNA <12 IU/mL, 12 weeks after treatment ended, sustained viral response12). The mean (±standard deviation) proteinuria decreased from 2.61 ± 1.01 at baseline to 1.71 ± 1.43 (g/day) at sustained viral response 48, p = 0.031; microscopic hematuria and serum cryoglobulins disappeared in six (50%) and seven (64%) patients, respectively, after sustained viral response by direct-acting antivirals. Adverse events occurred in 69% (9/13) of patients and were mild, with four cases of ribavirin-related anemia requiring blood transfusions (no drop-outs). After sustained viral response by direct-acting antivirals, immunosuppressive and immunomodulatory agents were initiated in clinical relapsers ( n = 2) and nonresponders ( n = 3) with some benefit. Among patients on interferon-based regimens ( n = 12), viral response (sustained viral response 24) and dropout rates were 58% (7/12) and 33% (4/12), respectively. After sustained viral response by interferon-based therapy, clinical relapsers ( n = 3) were successfully managed with immunosuppressive agents in two patients.

CONCLUSION

Treatment with direct-acting antivirals provides excellent rates of viral response and safety in patients with hepatitis C virus-related glomerular disease; viral response was frequently accompanied by clinical improvement. The absence of hepatitis C virus RNA from serum allowed immunosuppressive and immunomodulatory therapies with benefits for glomerular abnormalities and no concern on hepatitis C virus replication.

Clinical and morphologic spectrum of renal involvement in patients with HBV-associated cryoglobulinaemia

AIM

Cryoglobulinaemic glomerulonephritis related to hepatitis B virus (HBV) infection has been rarely reported. The aim of this study was to investigate the clinical features, renal biopsy findings in patients with HBV-associated cryoglobulinaemia.

METHODS

Twelve patients with HBV-associated cryoglobulinaemia were identified in this study. The demographic, clinical, pathological characteristics, treatment and follow-up data were analyzed.

RESULTS

Renal involvement was characterized by nephrotic range proteinuria with microscopic haematuria in all patients, and impaired renal function in nine patients (75%). Purpuric rash was the main extrarenal manifestation (58.3%). Type II cryoglobulinaemia was presented in three patients and type III in nine patients. Hypocomplementaemia and positive of rheumatoid factors were present in all patients. Membranoproliferative glomerulonephritis (MPGN) was observed in all kidney specimens. Seven patients also had evidence of prominent cryoglobulins thrombi on renal biopsy, but only three patients had HBV antigen deposits in renal tissues. Antiviral and steroids or immunosuppressive agents have been used in most of patients. During follow-up, two patients died, and four reaching end-stage renal disease; three patients had complete remission, and three patients had renal function improved after therapy.

CONCLUSIONS

Nephrotic syndrome with haematuria and renal insufficiency are the main clinical manifestation; cryoglobulinaemic glomerulonephritis are the main renal lesion in patients with HBV-Associated cryoglobulinaemia; half of patients have poor outcome even with antiviral and immunosuppressive therapy. The results of this study indicate that cryoglobulins should be detected in hepatitis B virus-Associated nephropathy in endemic area.

Extrahepatic manifestations of HCV: the role of direct acting antivirals

INTRODUCTION

Hepatitis C virus (HCV) represents a major health concern, as nearly 3 million people become newly infected by this pathogen annually. The majority of infected individuals fail to clear the virus, and chronicity is established. Chronic HCV patients are at high risk for liver disease, ranging from mild fibrosis to cirrhosis and severe hepatocellular carcinoma. Over the last few years, the development of multiple direct acting antivirals (DAA) have revolutionized the HCV infection treatment, demonstrating cure rates higher than 90%, and showing less side effects than previous interferon-based regimens. Areas covered: Besides liver, HCV infection affects a variety of organs, therefore inducing diverse extrahepatic manifestations. This review covers clinical, experimental, and epidemiological publications regarding systemic manifestations of HCV, as well as recent studies focused on the effect of DAA in such conditions. Expert commentary: Though further research is needed; available data suggest that HCV eradication is often associated with the improvement of extrahepatic symptoms. Therefore, the emergence of DAA would offer the opportunity to treat both HCV infection and its systemic manifestations, requiring shorter treatment duration and driving minor adverse effects.

Hepatitis E virus: Infection beyond the liver?

Hepatitis E virus (HEV) infections are not limited to the liver but may also affect other organs. Several diseases, including Guillain-Barré syndrome, neuralgic amyotrophy, glomerulonephritis, cryoglobulinemia, pancreatitis, lymphoma, thrombopenia, meningitis, thyroiditis and myocarditis have been observed in the context of hepatitis E. To date, the definite pathophysiological links between HEV and extrahepatic manifestations are not yet established. However, it is suggested that HEV infection might be causative based on serological studies, case series, in vitro data and animal models. In particular, neuronal and renal diseases as well as pancreatitis seem to be caused by HEV, while a causative relationship between HEV and other diseases is more doubtful. Either direct cytopathic tissue damage by extrahepatic replication, or immunological processes induced by an overwhelming host immune response, are possible origins of HEV-associated extrahepatic manifestations. Hepatologists should be aware of the possibility that acute or chronically HEV-infected patients could develop extrahepatic manifestations. Neurologists, nephrologists, rheumatologists and other groups of physicians should consider HEV infection as a potential differential diagnosis when observing one of the diseases described in this review. Ribavirin and steroids have been used in small groups of patients with extrahepatic manifestations of HEV, but the efficacy of these drugs still needs to be verified by large, multicenter studies. This article comprehensively reviews the published literature regarding HEV and extrahepatic manifestations. We discuss the probability of specific extrahepatic diseases being caused by previous or ongoing HEV infection, and summarize the published knowledge about antiviral treatment in extrahepatic disorders.

Hepatitis E Pathogenesis

Although most hepatitis E virus (HEV) infections are asymptomatic, some can be severe, causing fulminant hepatitis and extra-hepatic manifestations, including neurological and kidney injuries. Chronic HEV infections may also occur in immunocompromised patients. This review describes how our understanding of the pathogenesis of HEV infection has progressed in recent years.

Immunotactoid Glomerulopathy and Cryoglobulinemic Nephropathy: Two Entities with Many Similarities. A Unified Conceptual Approach

Immunotactoid glomerulopathy is a rare disorder that has been characterized at the ultrastructural level. Due to its rarity, there are few comprehensive studies relating to this disorder. Electron microscopy essentially characterizes this disease. The glomerular electron dense deposits which are typical of this condition consist of aggregates of highly organized microtubular structures of various diameters, but generally measuring 30-50 nm in width with a propensity to dispose themselves in parallel bundles intersecting in different planes. This study compares a large series of patients with cryoglobulinemic nephropathy with a series of patients with immunotactoid glomerulopathy to address whether there may be similarities that warrant considering these two entities part of a spectrum. This study reviews the clinicopathologic features of both entities and emphasizes ultrastructural findings that characterize them. Significant immunomorphologic overlap was found when these two disorders were compared in this study. There were also striking similarities in clinical presentation/behavior, laboratory findings and prognosis. Proteomic analysis has also demonstrated similar spectra for both entities. We postulate that immunotactoid glomerulopathy and cryoglobulinemic nephropathy are part of the spectrum of renal manifestations in patients with circulating cryoglobulins and renal disease.

Extrahepatic manifestations of hepatitis E virus

Hepatitis E virus can cause acute, fulminant and chronic hepatitis and has been associated with a range of extrahepatic manifestations. Guillain-Barré syndrome, neuralgic amyotrophy and encephalitis are the main neurological manifestations associated with acute and chronic hepatitis E virus infection. Renal injuries have been also reported, including membranoproliferative glomerulonephritis with or without cryoglobulinemia and membranous glomerulonephritis. Acute pancreatitis, haematological disorders and other autoimmune extrahepatic manifestations of hepatitis E virus, such as myocarditis and thyroiditis, have been also reported. In this comprehensive article, we review all published reports describing hepatitis E virus-associated extrahepatic manifestations.

Hepatitis E Virus-Induced Cryoglobulinemic Glomerulonephritis in a Nonimmunocompromised Person

Hepatitis E virus (HEV)-related kidney disease and symptomatic cryoglobulinemia have been observed in solid-organ transplant recipients. However, HEV RNA in the cryoprecipitate has not yet been assessed. We report what to our knowledge is the first documented case of autochthonous HEV-induced cryoglobulinemic crescentic and membranoproliferative glomerulonephritis in an immunocompetent man with no notable medical history. He presented with edema, hypertension, increased serum creatinine level, and nephrotic syndrome. Type II cryoglobulinemia with monoclonal immunoglobulin G (IgG) κ light chain was detected. Anti-HEV IgG and IgM, as well as HEV RNA, were detected in serum and cryoprecipitate. Histologic analysis of a kidney biopsy specimen revealed features of crescentic and membranoproliferative glomerulonephritis. After HEV clearance, kidney and liver parameters improved and HEV RNA and cryoglobulinemia were undetectable. Hence, we conclude that HEV can cause severe kidney disease and should be considered in cases of unexplained glomerular disease.

Proliferative Glomerulonephritis With Monoclonal IgG1κ Deposits in a Hepatitis C Virus-Positive Patient

Hepatitis C virus infection is associated with several glomerular diseases, most commonly cryoglobulinemic glomerulonephritis, which is typically secondary to type II mixed cryoglobulinemia. We present a patient with hepatitis C virus infection and cryoglobulinemic glomerulonephritis secondary to type I (monoclonal) cryoglobulinemia that is likely related to a concurrent hepatitis C virus infection-associated lymphoproliferative disorder. We list the differential diagnosis of cryoglobulinemic glomerulonephritis. Additionally, the case draws attention to the possibility that, rarely, even clinically undetectable "occult" B-cell lymphoproliferative disorders may result in significant kidney disease.

Successful treatment of hepatitis E virus-associated cryoglobulinemic membranoproliferative glomerulonephritis with ribavirin

Hepatitis E virus genotype-3 (HEV3) infection can cause chronic hepatitis in immunosuppressed patients and induce extra-hepatic manifestations, such as neurological symptoms, kidney injuries, and immune-mediated thrombocytopenia. Very few cases of HEV-induced kidney manifestations have been reported. Herein, we report, for the first time, a case of de novo membranoproliferative glomerulonephritis that occurred in a kidney transplant patient who developed a chronic HEV3 infection, which was successfully treated with ribavirin.

The many faces of cryoglobulinemic nephropathy: a clinico-pathologic study of 47 cases with emphasis on the value of electron microscopy

The clinical and pathologic manifestations of cryoglobulinemic nephropathy (CN) are heterogeneous. The role that electron microscopy plays in the diagnosis of CN has not been properly evaluated. The main objective of this study was to define the value of ultrastructural evaluation in the diagnosis of CN. Although most of the CN cases in this series exhibited glomerular pathology with a membranoproliferative pattern, a significant number of the cases showed less well-defined morphologic patterns on light microscopic examination (i.e. mesangial proliferation, hyaline thrombi in glomerular capillaries without significant cellular proliferation, exudative glomerulonephritis, etc). Immunofluorescence microscopy also revealed variable immunoglobulin and complement component patterns, some with "full-house" expression of immunoreactants. A subset of these CN cases was associated with light chain restriction. Thus, differential diagnosis can be a challenge as many other glomerulonephritis overlap in immunomorphologic characteristics. Because the immunomorphologic manifestations of CN are so varied, confirmation of a suspected diagnosis of CN or making a diagnosis in a less than a typical immunomorphologic setting required careful ultrastructural evaluation to find unequivocal diagnostic findings or at least supportive evidence in the form of detection of substructure in the electron dense glomerular deposits consistent with cryoglobulins. Even in cases where the light and immunofluorescence findings in suspicious clinical situations were quite consistent with CN, electron microscopy provided the final proof to substantiate the diagnosis in the great majority of the cases.

The Unravelled Link between Chronic Kidney Disease and Hepatitis C Infection

The 2011 report of the World Health Organization General Assembly on noncommunicable diseases identified chronic kidney disease as a worldwide health issue posing a heavy economic burden. Hepatitis C virus infection, which is responsible for over 1 million deaths resulting from cirrhosis and liver cancer, is linked to chronic kidney disease in several ways; some forms of renal disease are precipitated by hepatitis C and patients with end-stage chronic renal disease are at increased risk for acquiring HCV. The aim of this review is to update the evidence on the relationship between hepatitis C infection and chronic kidney disease. Information has been accumulated in the last decade indicating that HCV plays an adverse effect on the incidence and progression of chronic kidney disease; a novel meta-analysis of observational studies (seven longitudinal studies; 890,560 unique individuals) found a relationship between hepatitis C seropositivity and incidence of reduced estimated glomerular filtration rate (adjusted relative risk, 1.70; 95% CI, 1.20; 2.39; P=0.002) in the adult general population. In addition to conventional risk factors, hepatitis C may be an additional factor for the development of chronic kidney disease, and an atheromasic activity of hepatitis C virus has been mentioned. The link between hepatitis C and atherosclerosis could also explain the excess risk of cardiovascular mortality that has been observed among hepatitis C virus seropositive patients undergoing maintenance dialysis. A number of biologically plausible mechanisms related to hepatitis C virus have been hypothesized to contribute to atherosclerosis. Implementation of effective treatment intervention towards hepatitis C is required to decrease the healthcare burden of hepatitis C and to prevent the progression of chronic renal disease.

Acute kidney injury in a diabetic haemophiliac: one step at a time

We present a young man with type 1 diabetes mellitus and haemophilia A; who presented with oliguric acute kidney injury (AKI). He is also known to have chronic hepatitis C virus infection. On presentation, he had an active urinary sediment warranting a renal biopsy for definitive diagnosis and management. Although he was at high risk for bleeding we elected for renal biopsy with appropriate factor VIII supplementation and monitoring. Ultrasound-guided percutaneous renal biopsy was successful with no immediate or long-term complications. Biopsy revealed advanced diabetic glomerulosclerosis with mild chronic interstitial inflammation.

Hepatitis C virus infection in nephrology patients

CONTEXT

Hepatitis C virus (HCV) infection leads to chronic liver disease, but also to extra-hepatic manifestations.

EVIDENCE ACQUISITIONS

Directory of Open Access Journals (DOAJ), Google Scholar, Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched.

RESULTS

Herein, we provide an overview of renal diseases related to HCV and their therapies, as well as the treatment options available for HCV (+)/RNA (+) dialysis patients. We will not mention, however, HCV infection-related complications in the post-kidney transplantation setting.

CONCLUSIONS

Extra-hepatic manifestations of HCV infection include mixed cryoglobulinemia, lymphoproliferative disorders, and renal disease. HCV infection has been reported in association with distinct histological patterns of glomerulonephritis in native kidneys.

Renal involvement in HCV-related vasculitis

Renal involvement has been frequently reported in the setting of hepatitis C virus (HCV) infection. The most common renal pathology associated with chronic HCV infection is type I membranoproliferative glomerulonephritis associated with type II mixed cryoglobulinemia, while membranoproliferative glomerulonephritis without cryoglobulinemia and membranous nephropathy were less frequently reported. Rarely, focal segmental glomerulosclerosis, fibrillary and immunotactoid glomerulopathies, and thrombotic microangiopathies were described during the course of HCV infection. In the present review, we have focused on renal involvement in HCV-related vasculitis.

Life-Threatening Cryoglobulinemic Patients With Hepatitis C: Clinical Description and Outcome of 279 Patients

Cryoglobulinemia is characterized by a wide range of causes, symptoms, and outcomes. Hepatitis C virus (HCV) infection is detected in 30%-100% of patients with cryoglobulins. Although more than half the patients with cryoglobulinemic vasculitis present a relatively benign clinical course, some may present with potentially life-threatening situations. We conducted the current study to analyze the clinical characteristics and outcomes of HCV patients presenting with life-threatening cryoglobulinemic vasculitis. We evaluated 181 admissions from 89 HCV patients diagnosed with cryoglobulinemic vasculitis consecutively admitted to our department between 1995 and 2010. In addition, we performed a systematic analysis of cases reported to date through a MEDLINE search.The following organ involvements were considered to be potentially life-threatening in HCV patients with cryoglobulinemic vasculitis: cryoglobulinemic, biopsy-proven glomerulonephritis presenting with renal failure; gastrointestinal vasculitis; pulmonary hemorrhage; central nervous system (CNS) involvement; and myocardial involvement. A total of 279 patients (30 from our department and 249 from the literature search) fulfilled the inclusion criteria: 205 presented with renal failure, 45 with gastrointestinal vasculitis, 38 with CNS involvement, 18 with pulmonary hemorrhage, and 3 with myocardial involvement; 30 patients presented with more than 1 life-threatening cryoglobulinemic manifestation. There were 146 (52%) women and 133 (48%) men, with a mean age at diagnosis of cryoglobulinemia of 54 years (range, 25-87 yr) and a mean age at life-threatening involvement of 55 years (range, 25-87 yr). In 232 (83%) patients, life-threatening involvement was the first clinical manifestation of cryoglobulinemia. Severe involvement appeared a mean of 1.2 years (range, 1-11 yr) after the diagnosis of cryoglobulinemic vasculitis. Patients were followed for a mean of 14 months (range, 3-120 mo) after the diagnosis of life-threatening cryoglobulinemia. Sixty-three patients (22%) died. The main cause of death was sepsis (42%) in patients with glomerulonephritis, and cryoglobulinemic vasculitis itself in patients with gastrointestinal, pulmonary, and CNS involvement (60%, 57%, and 62%, respectively). In conclusion, HCV-related cryoglobulinemia may result in progressive (renal involvement) or acute (pulmonary hemorrhage, gastrointestinal ischemia, CNS involvement) life-threatening organ damage. The mortality rate of these manifestations ranges between 20% and 80%. Unfortunately, this may be the first cryoglobulinemic involvement in almost two-thirds of cases, highlighting the complex management and very elevated mortality of these cases.

De Novo Fibrillary Glomerulonephritis (FGN) in a Renal Transplant with Chronic Hepatitis C

Chronic hepatitis C viremia (HepC) has been associated with numerous renal manifestations both in native kidneys and in the setting of renal transplantation. Glomerulonephritis (GN) of the renal allograft in the setting of HepC most commonly manifests as type 1 membranoproliferative GN (MPGN), either representing recurrence of the original disease or arising de novo. Other GNs were reported after transplantation in the patient with HepC including membranous nephropathy and thrombotic microangiopathy, as well as an enhanced susceptibility to transplant glomerulopathy. We describe the first case of de novo fibrillary GN in a renal transplant patient with HepC where the primary renal disease was biopsy proven type 1 MPGN. We discuss this relationship in detail.

Remission of HCV-associated Glomerulonephritis with Pegylated IFN and Ribavirin Therapy after Liver Transplantation: Case Report and Literature Review

Background

Hepatitis C virus infection is associated with a variety of extrahepatic disorders such as membrano-proliferative glomerulonephritis, which is generally due to cryoglobulinemia.

Setting

We describe the case of one liver transplant recipient who received antiviral therapy (subcutaneous administration of peg-IFN-alpha-2a 180 mcg weekly and oral ribavirin 200 mg thrice a day) for HCV-related membrano-proliferative glomerulonephritis. He presented normal kidney function, non-nephrotic proteinuria (2 g/24 h) and mild hematuria.

Results

Urinary abnormalities disappeared within a few weeks after the initiation of antiviral therapy; however, combination antiviral therapy was not able to obtain viral clearance. After 11 months, IFN-therapy was interrupted and the patient continued low-dose ribavirin monotherapy (200 mg once per day) for one additional year- remission of proteinuria (<0.3 g/24 h) and hematuria persisted with intact kidney function. Although other mechanisms cannot be excluded, we suggest that ribavirin therapy was critically implicated in the remission of urinary abnormalities in our patient. The existing literature on the association between HCV-associated glomerulonephritis and therapy with ribavirin is reviewed.

Conclusions

Antiviral therapy may be effective in patients with HCV-induced glomerulonephritis. Further evidence is needed to evaluate efficacy and safety of ribavirin monotherapy for HCV-related glomerulonephritis.

Antiviral therapy for HCV-associated cryoglobulinemic glomerulonephritis: case report and review of the literature

We describe the case of a 51-year-old woman with HCV-associated cryoglobulinemic glomerulonephritis (GN). She presented mild deterioration of kidney function, non-nephrotic proteinuria, and active urinary sediment. Kidney biopsy showed features of membranoproliferative changes with some sclerosis. Sustained viral response (SVR) was obtained by 6 months of antiviral therapy (peg-IFN-α2a plus ribavirin). SVR was linked with improvement of kidney function and remission of proteinuria. Clinical and virological remission persists over a 25-month follow-up. This case report emphasizes efficacy and safety of antiviral treatment of HCV-associated glomerulonephritis--preliminary but encouraging results exist. We identified by systematic review of the literature 9 studies (156 unique patients); the pooled estimate of frequency of sustained virological response after IFN-based therapy was 0.49 (95% confidence interval, CI: 0.21, 0.77; p < 0.0005; random effects model). Heterogeneity was found (I(2) = 98.9%, p < 0.0001). Two possible regimens should be considered for the treatment of HCV-associated cryoglobulinemic GN according to the clinical presentation. Immunosuppressive therapy is recommended for HCV-related kidney disease having aggressive course, and recent evidence supports rituximab (RTX) use with a reduced exposure to corticosteroids. We identified six studies (66 unique patients) on RTX therapy for HCV-associated kidney disease; at the end of RTX therapy, the pooled estimate of the mean decrease in proteinuria was 1.4 g/24 h (95% CI: 0.75, 2.05, p < 0.001); The p test for heterogeneity gave a value of 0.94 (I(2) = 0). Several questions related to RTX use remain. HCV-induced GN is uncommon among CKD patients of developed countries, and this clearly hampers prospective controlled clinical trials aimed to evaluate efficacy and safety of antiviral or immunosuppressive therapy in this population.

Hepatitis C virus infection, mixed cryoglobulinemia, and kidney disease

Hepatitis C virus (HCV) may instigate mixed cryoglobulinemia; the most significant accompanying kidney lesion is type I membranoproliferative glomerulonephritis, usually occurring in the context of type II mixed cryoglobulinemia. Additionally, recent data support a link between HCV infection and proteinuria in population-based studies, raising the possibility that kidney diseases associated with HCV may be more common than previously thought. A number of strategies have been used to treat HCV-related glomerulonephritis, including antiviral agents, immunosuppressive therapies such as corticosteroids and cytotoxic agents, and plasma exchange. Limited but encouraging data about the utility of antiviral treatment in the setting of HCV-associated glomerulonephritis exist, with one pooled analysis noting a sustained viral response of 42%, albeit with significant heterogeneity. Immunosuppressive therapy may be most useful for cryoglobulinemic kidney disease, with individualized approaches considered for the treatment of HCV-associated cryoglobulinemic glomerulonephritis based on the level of proteinuria and kidney failure. Of note, rituximab, a chimeric monoclonal antibody that blocks CD20 receptors on B cells, has been reported to be effective for the treatment of mixed cryoglobulinemia symptoms, including glomerulonephritis.

Treatment of hepatitis C cryoglobulinemia: mission and challenges

Mixed cryoglobulinemia (MC) is a syndrome resulting from cold-insoluble immunoglobulin complexes or cryoglobulins (CGs) that precipitate in the serum of 40% to 50% of patients with chronic hepatitis C virus (HCV) infection. The pathogenesis of cryoglobulinemia likely occurs due to chronic viremia and generation of rheumatoid factor following continuous presentation of antigen-immunoglobulin complexes to B cells. CGs are thought to be responsible for a variety of extrahepatic manifestations associated with HCV, including vasculitis, glomerulonephritis, arthritis, and neuropathies, which occur in approximately 10% of HCV patients with CGs. CGs also are a powerful predictive factor for progressive liver disease and the aggressive reoccurrence of liver disease in HCV-positive patients after liver transplantation. First-line therapy for MC due to HCV infection is antiviral therapy with pegylated interferon-alpha and ribavirin. Viral eradication usually produces marked reduction of physical complications and arrests end organ damage concomitant with clearance of CG. Additional prospective, controlled studies are necessary to determine whether CG influences patient virologic response and/or its durability to antiviral therapy. Immunomodulators such as corticosteroids and cyclophosphamide are efficacious for palliative treatment of the symptomatology of HCV cryoglobulinemia but may enhance viral replication. Consequently, prolonged therapy with immunomodulatory agents should be limited to severe vasculitis or aggressive glomerulonephritis in patients with MC due to HCV who have failed to respond to antiviral therapy. In acute, fulminant presentations, plasmapheresis may provide temporary relief and arrest the rapid progression of the disease so that additional therapy can be initiated.

Morphologic features of extrahepatic manifestations of hepatitis C virus infection

Cirrhosis and hepatocellular carcinoma are the prototypic complications of chronic hepatitis C virus infection in the liver. However, hepatitis C virus also affects a variety of other organs that may lead to significant morbidity and mortality. Extrahepatic manifestations of hepatitis C infection include a multitude of disease processes affecting the small vessels, skin, kidneys, salivary gland, eyes, thyroid, and immunologic system. The majority of these conditions are thought to be immune mediated. The most documented of these entities is mixed cryoglobulinemia. Morphologically, immune complex depositions can be identified in small vessels and glomerular capillary walls, leading to leukoclastic vasculitis in the skin and membranoproliferative glomerulonephritis in the kidney. Other HCV-associated entities include porphyria cutanea tarda, lichen planus, necrolytic acral erythema, membranous glomerulonephritis, diabetic nephropathy, B-cell non-Hodgkin lymphomas, insulin resistance, sialadenitis, sicca syndrome, and autoimmune thyroiditis. This paper highlights the histomorphologic features of these processes, which are typically characterized by chronic inflammation, immune complex deposition, and immunoproliferative disease in the affected organ.

Hepatitis C virus infection and mixed cryoglobulinemia

Hepatitis C virus (HCV) chronic infection is recognized as the major cause of mixed cryoglobulinemia (MC). Its persistence represents a continuous stimulus for host immune system with production of circulating immune complexes (ICs), one-third of them with cryoprecipitate property. Several factors contribute to the biological activities of ICs, many of which are not completely known. Among them, complement factors play a crucial role in the cold-insoluble ICs-mediated vasculitis, involving primarily small blood vessels in different tissues including skin, kidney, peripheral, and central nervous system. Liver represents the major target of HCV infection with inflammatory infiltrates, resembling secondary lymphoid follicles. Cytokine like CXCL13 contribute to B-cell homing in intraportal lymphoid aggregates, in which B-cell clonal selection may arise. B-cell clonal expansion starts as an antigen-driven event and expands towards indolent and malignant B-cell proliferation. Occurrence of intrahepatic B-cell clonalities correlates with extrahepatic clinical manifestations of HCV infection. In this context, cryoglobulinemic patients should be considered a peculiar HCV-infected population that needs a clinical multidisciplinary approach and more articulated therapeutic measures.