Cryoglobulins in chronic hepatitis C virus infection

Insights into the immunological description of cryoglobulins with regard to detection and characterization in Slovenian rheumatological patients

The detection of cryoglobulins (CG) used to diagnose cryoglobulinemic vasculitis requires strict adherence to protocol, with emphasis on the preanalytical part. Our main objectives were to introduce a more sensitive and specific protocol for the detection of CG and to characterize CG in Slovenian patients diagnosed with cryoglobulinemic vasculitis, other vasculitides, connective tissue diseases or non-rheumatic diseases examined at the Department of Rheumatology (University Medical Centre Ljubljana). Samples were routinely analyzed for the presence of CG with the protocol using the Folin-Ciocalteu reagent. In the newly introduced protocol, the type of CG was determined by immunofixation on visually observed positive samples and the concentration of CG in the cryoprecipitate and rheumatoid factor (RF) activity were measured by nephelometry. RF, C3c and C4 were measured in patients` serum and a decision tree analysis was performed using all results. The agreement between negative and positive results between the two protocols was 86%. Of the 258 patient samples tested, we found 56 patients (21.7%) with positive CG (37.5% - type II, 62.5% - type III). The RF activity was observed in 21.4% of CG positive subjects. The median concentration of type II CG was significantly higher than that of type III CG (67.4 mg/L vs. 45.0 mg/L, p = 0.037). Patients with type II had lower C4 concentrations and higher RF compared to patients with type III CG. In the decision tree, C4 was the strongest predictor of cryoglobulinemia in patients. With the newly implemented protocol, we were able to improve the detection and quantification of CG in the samples of our rheumatology patients and report the results to adequately support clinicians.

Understanding the Cryoglobulinemias

PURPOSE OF THE REVIEW

Cryoglobulins are immunoglobulins with the ability to precipitate at temperatures <37 °C. They are related to hematological disorders, infections [especially hepatitis C virus (HCV)], and autoimmune diseases. In this article, the state of the art on Cryoglobulinemic Vasculitis (CV), in a helpful and schematic way, with a special focus on HCV related Mixed Cryoglobulinemia treatment are reviewed.

RECENT FINDINGS

Direct - acting antivirals (DAA) against HCV have emerged as an important key in HCV treatment to related Cryoglobulinemic Vasculitis, and should be kept in mind as the initial treatment in non-severe manifestations. On the other hand, a recent consensus panel has published their recommendations for treatment in severe and life threatening manifestations of Mixed Cryoglobulinemias. HCV-Cryoglobulinemic vasculitis is the most frequent form of CV. There are new treatment options in HCV-CV with DAA, with an important number of patients achieving complete response and sustained virologic response (SVR). In cases of severe forms of CV, treatment with Rituximab and PLEX are options. The lack of data on maintenance therapy could impulse future studies in this setting.

Type 1 Immunoglobulin M Cryoglobulinemic Vasculitis in a Patient with Chronic Lymphocytic Leukemia and a History of Hepatitis C Virus: Is There a Link?

Hepatitis C virus (HCV) is considered a hepatotropic and, increasingly, a lymphotropic virus. Research suggests an association between HCV infection and the subsequent development of non-Hodgkin lymphomas (NHL). HCV is also a well-known etiologic factor in the development of type II cryoglobulinemic vasculitis while type I cryoglobulinemic vasculitis results from monoclonal immunoglobulin secondary to malignancy. Is there a link among HCV, NHL, and type I cryoglobulinemia? This question is posed in a case of aggressive type 1 cryoglobulinemic vasculitis in a patient with chronic lymphocytic leukemia and a history of HCV. I theorize on an intriguing pathogenesis of how HCV may have led to B cell malignancy and the subsequent development of type I cryoglobulinemic vasculitis in this patient.

HCV-negative mixed cryoglobulinemia and kidney involvement: in-depth review on physiopathological and histological bases

Type II mixed cryoglobulinemia without evidence of HCV infection but rather with renal involvement has been occasionally described. The pathogenesis of cryoglobulinemic kidney disease is most likely related to immune complex deposition including cryoglobulins, and cryoaggregation after cold exposure could play a pivotal role in clinical expression of cryoglobulinemia. In these cases, acute kidney injury and proteinuria remain the most frequent clinical expression of a cryoglobulinemic glomerulonephritis. Type II cryoglobulinemia with the laboratory finding of both monoclonal and polyclonal cryoglobulins is the most prevalent bio-humoral pattern among HCV-negative phenotypes with renal involvement, while type III cryoglobulinemia with polyclonal Ig is rare. Histological data in renal biopsies support the hypothesis that regardless of the HCV status cryoglobulinemia vasculitis share the same frequent pathological finding of membranoproliferative glomerulonephritides, but other histological patterns have also been observed in a minority of cases. In HCV-negative mixed cryoglobulinaemia, the paraneoplastic origin of the immune dysfunction should be ruled out and sporadic cases have been reported, while there is no cumulative evidence on the prevalence of these tumour-associated manifestations. Moving from the classification criteria and the etiopathogenesis of mixed cryoglobulinaemia, we provide a comprehensive review of the literature on the appearance of the disease with kidney injury in association with malignancies or autoimmune disorders without HCV coexistence.

Sofosbuvir-daclatasvir improves hepatitis C virus-induced mixed cryoglobulinemia: Upper Egypt experience

BACKGROUND AND AIMS

Hepatitis C virus (HCV) infection is associated with extrahepatic manifestations such as cryoglobulinemia and accounts for up to 90% of all cases of mixed cryoglobulinemia (MC). The present study aimed to evaluate the effect of sofosbuvir-daclatasvir therapy on symptomatic HCV-related MC and sustained virologic response (SVR) achievement.

PATIENTS AND METHODS

This prospective cohort study was carried out on 120 patients with chronic HCV infection, clinically suspected to have MC, but only 63 of whom were positive for cryoglobulins. HCV-MC patients were treated with sofosbuvir 400 mg and daclatasvir 60 mg once daily for 3 months. The serum cryoglobulins levels, complement 3 (C3), complement 4 (C4) (using ELISA assay kits) and rheumatoid factor (RF) (using immunoturbidimetric assay kit), were measured in the included HCV infected patients (to confirm HCV-MC diagnosis), in addition to quantitave HCV-RNA assays, using real time PCR. All these measurements have been done before stating therapy and 12, 24 weeks post-therapy for assessments of immunological recovery, viral load and SVR.

RESULTS

Significant increase in the serum cryoglobulin levels and RF with significant decrease in C3 and C4 serum levels were detected in only 63 out of 120 included HCV infected patients, upon whom the study has been completed. They showed significant decrease in their mean cryoglobulin levels from 41.47 µg/mL ±12.32 SD to 5.12 µg/mL ±3.59 SD then to 5.09 µg/mL ±3.02 SD, 12 to 24 weeks post-therapy respectively (p<0.001), with significant decline in RF concentrations and rise in C3 and C4 serum levels approaching the normal values. There were improvements in the presenting HCV-MC clinical manifestations in variable degrees, ranging from 5 (71.42%) in patients with glomerulonephritis to 62 (98.4%) in patients with purpura. Eighty-seven percent of the included patients showed complete response (clinical, virological and immunological recovery) and 13% showed partial response (virological and immunological recovery without clinical improvement of cryoglobulinemia associated manifestations).

CONCLUSION

A combined therapy of sofosbuvir 400 mg and daclatasvir 60 mg once daily for 3 months was associated with a significant decrease in serum cryoglobulin levels and appears as a reasonable treatment option for HCV-associated MC.

Hepatitis C virus positive patient diagnosed after detection of atypical cryoglobulin

A 60-year-old male patient presented with jaundice and dark urine for three days, icteric sclerae and skin rash on his legs for six months. Laboratory investigations revealed an atypical cryoglobulinemia with high hepatitis C virus (HCV)-RNA levels. Imaging studies showed cholestasis was accompanying HCV. Capillary zone electrophoresis using immunosubtraction method revealed a polyclonal immunoglobulin G and immunoglobulin A (IgA) monoclonal cryoglobulin and that IgA lambda was absent in immunofixation electrophoresis. After a liver biopsy, chronic hepatitis C, HCV related mixed cryoglobulinemia and cryoglobulinemic vasculitis were diagnosed and antiviral therapy was initiated. Our HCV patient presented with cryoglobulinemic symptoms with an atypical cryoglobulinemia that was detected by an alternative method: Immunosubtraction by capillary electrophoresis. Different types of cryoglobulins may therefore have a correlation with clinical symptoms and prognosis. Therefore, the accurate immunotyping of cryoglobulins with alternative methods may provide more information about cryoglobulin-generated pathology.

B cell reductive therapy in the treatment of autoimmune diseases: A focus on monoclonal antibody treatment of rheumatoid arthritis

The therapeutic approach to patients with autoimmune disorders is in the midst of a dramatic change. Monoclonal antibody technology has allowed us to dissect and now manipulate the human immune system with greater precision. It is now widely recognized that B lymphocytes play a role in the pathogenesis of many autoimmune diseases, though the extent and contribution is a matter of debate and active investigation. There is emerging data to suggest that both antibody-dependent and independent mechanisms contribute to disease pathogenesis. However, given the heterogeneous nature of autoimmune diseases, and the varied responses to B lymphocyte reduction, the role of B lymphocytes is likely disease-specific. The two clinical trials discussed in this review demonstrate remarkable consistency in the ability of B cell reduction to ameliorate the clinical manifestations of rheumatoid arthritis with minimal toxicity. B lymphocyte targeted approaches to autoimmune disease in general, and RA specifically, will not only provide an effective and potentially less toxic alternative treatment option, but also allow for a better understanding of the pathogenesis of these complex and morbid diseases.

A rheumatoid factor paradox: inhibition of rituximab effector function

Introduction

Rituximab (RTX) therapy of rheumatoid arthritis (RA) exhibits enhanced effectiveness in seropositive patients. Using patient sera, we tested if this improved efficacy was associated with enhanced RTX mediated complement-dependent cytotoxicity (RTX-CDC).

Methods

We developed an in vitro assay for RTX-CDC using patient sera and the Daudi human B cell line. Using propidium iodide uptake and flow cytometry, we compared RTX-CDC with rheumatoid factor (RF)+ sera relative to normal volunteer, non-RA and RF- sera. Additional studies examined mixing studies of RF+ and RF- sera, as well as the effect of monoclonal IgA or IgM RF. Finally, the effect of RF on RTX mediated trogocytosis of normal B cells was evaluated.

Results

Using human sera, addition of RTX resulted in rapid and profound (> 50%) Daudi cell death that was complement dependent. Surprisingly, RF+ patient sera exhibited reduced RTX-CDC relative to RF- sera, with an inverse relationship of RTX-CDC and RF titer. Mixing studies indicated the presence of an inhibitor of RTX-CDC in RF+ sera. The addition of monoclonal IgM or IgA RF to RF- sera markedly inhibited RTX-CDC. This effect was specific for RF binding to the Fc portion of RTX as it was not apparent with the F(ab)' domains of RTX engineered onto IgG3 heavy chain. RF also modestly inhibited RTX mediated trogocytosis.

Conclusions

Contrary to expectations, RF+ sera exhibits reduced RTX-CDC due to the presence of RF. The enhanced efficacy of RTX in seropositive RA patients cannot be attributed to improved B cell depletion through CDC. This result indicates that high RF levels may potentially modulate the efficacy of any therapeutic monoclonal antibody dependent on Fc effector function.

Cryoglobulin evaluation: best practice?

Cryoglobulins are serum immunoglobulins that precipitate at temperatures below 37 degrees C and re-dissolve on warming. Cryoglobulinaemia leads to variable symptoms including characteristic purpura, ischaemia of extremities, renal failure, peripheral neuropathy, abdominal pain secondary to intestinal ischaemia and arthralgias. Cryoglobulin testing is underutilized in clinical practice. It has been neglected in clinical laboratories and by clinicians due to several factors, such as the length of time it takes for serum cryoglobulin analysis to be performed in the laboratory, the perceived difficulty in getting optimal sampling conditions and a failure to appreciate that even apparently low levels of cryoglobulin can be associated with severe symptoms in some patients. The most important variable confounding standardization of cryoglobulin testing is improper sample handling. A recent report critically appraising the current practice of cryoglobulin evaluation in 137 laboratories in Europe by United Kingdom National External Quality Assurance Scheme (UKNEQAS) illustrated the wide variability in practice. Although many clinical laboratories perform cryoglobulin evaluation, there are widespread differences in the methodology used and the care with which this is carried out and this leads to considerable intralaboratory and interlaboratory variability. The most common sources of error are false-negative results due to loss of cryoprecipitate during transport and storage. Better standardization is needed to avoid missed diagnoses and improve the comparability of results. Laboratories should ensure that sample temperature is maintained at 37 degrees C until the serum is separated. In this article, we briefly review the classification and clinical features of cryoglobulins and suggest best practice guidelines for laboratory detection and identification of cryoglobulins.

Mixed cryoglobulinemia: a model of virus-related disease in internal medicine

Like other hepatotropic viruses, hepatitis C virus (HCV) exhibits the property of inducing hepatocellular damage, possibly through induction of immune mechanisms that lead to hepatocellular necrosis. The early activated mechanisms include production of non-specific and specific antibodies, which represent the first line of defence against invading foreign pathogens. As a consequence, circulating immune complexes are promptly formed and antigen uptake and processing by specialized cells are enhanced. A major fraction of circulating immunoglobulins (Igs) are part of the spectrum of so-called "natural" antibodies, which include anti-idiotypic antibodies and molecules with rheumatoid factor (RF) activity. They mainly belong to the IgM class, are polyclonal and have no intrinsic pathogenetic potential. In 20-30% of HCV-infected patients, RFs share characteristics of high affinity molecules, are monoclonal in nature, and result in the production of cold-precipitating immune complexes and mixed cryoglobulinemia (MC). The persistent production of monoclonal RF molecules implies the existence of a further mechanism capable of restricting the reactivity and reflects a distinct selection of a cell population that can be maintained throughout life because it is continuously exposed to antigen pressure. Either polyclonal or monoclonal profiles of B-cell expansion are demonstrable in the liver of the majority of HCV-infected patients. The frequent detection of oligoclonal B cell expansion may, indeed, represent a key pathobiologic feature which sustains non-malignant B-cell lymphoproliferation. The preferential expansion of one clone would in turn lead to a monoclonal pattern, which could favor stochastic oncogenic events. Thus, it can be postulated that HCV is the stimulus not only for the apparent benign lymphoproliferative process underlying a wide spectrum of clinical features, but also for the progression to frank lymphoid malignancy in a subgroup of patients.

Cryoglobulinemia in chronic hepatitis C: clinical aspects and response to treatment with interferon alpha and ribavirin

INTRODUCTION: The main extra-hepatic manifestation of hepatitis C is mixed cryoglobulinemia (MC). The aim of this study was to evaluate its prevalence among patients with chronic hepatitis C (CHC), to correlate its presence to host and virological variables and to the response to combined therapy with interferon-alpha and ribavirin. CASUISTIC AND METHODS: 202 CHC naive patients (136 with chronic hepatitis and 66 with cirrhosis) were consecutively evaluated for the presence of cryoglobulins. Cryoprecipitates were characterized by immunoelectrophoresis and classified according to the Brouet's criteria. RESULTS: The prevalence of MC was 27% (54/202), and 24% of them (13/54) showed major clinical manifestation of the disease. Even though type III MC was more frequent (78%), symptomatic MC was more common in type II MC. The presence of cirrhosis (RR = 2.073; IC95% = 1.029 - 4.179; p = 0.041), and age of the patients (RR = 1.035; IC95% = 1.008 - 1.062; p = 0.01) were independently associated with the presence of cryoglobulins. No relationship was found with viral load and genotype. 102 patients were treated with interferon alpha and ribavirin. Among these, 31 had MC. Sustained virological response (around 30%) was similar in patients with and without MC (p = 0.971). CONCLUSION: MC represents a prevalent complication in patients with CHC, specially older and cirrhotic patients. Only 24% of these patients show clinical manifestation of the disease, specially those with type II MC. The presence of MC did not affect the response to therapy.

Hepatitis C and arthritis: an update

Extrahepatic symptoms during chronic hepatitis C virus (HCV) infection are common and varied. Arthritis can be seen either as part of autoimmune processes (eg, associated with cryoglobulinemia) or independently. Whether the manifestation is specifically attributable to HCV infection or rather to the nonspecific result of a chronic inflammatory process is not clear. The literature available at this time is insufficient to guide the most appropriate course of treatment of HCV arthritis. Standard antirheumatic treatment can be considered, but with caution, because some of these medications occasionally may be hepatotoxic and response to therapy seems variable. Treatment decisions should be determined on a case-by-case basis.

Cryoglobulinemia in Kidney Transplant Recipients

The aim of this study was to assess the presence of cryoglobulins, the constitution of the cryoprecipitate, as well as the possible etiology and clinical features in kidney transplant recipients. We excluded patients with clinical or laboratory evidence of autoimmune, liver or neoplasm disease, infections, blood transfusions or immunizations in the previous 3 months. Detection of cryoglobulins was obtained from the peripheral venous blood. In cases of cryoprecipitate formation it was analyzed using anti-IgG, anti-IgM, anti-IgA, anti-C3, and anti-C4 antibodies. The hepatitis C virus (HCV) was detected by the polymerase chain reaction. Thirty-nine patients were selected, of whom 23 were men and the overall mean age was 40.6 +/- 12.7 years. Cryoprecipitate was detected in 74.4% (29/39) patients. Among patients with or without cryoprecipitate formation, the serum creatinine values, the percentage of patients with proteinuria, and the posttransplantation times were similar. In patients with cryoglobulins, 37.9% (11/29) were HCV positive. The etiology was not determined for the other patients. The IgG, IgM, and IgA immunoglobulins and the complement fractions C3 and C4 were found in the cryoprecipitate. Their compositions were similar among patients with or without HCV. Few clinical features were associated with the presence of cryoglobulins, including deep venous thrombosis, cutaneous purpura and peripheral neuropathy. In conclusion, cryoglobulinemia was prevalent in kidney transplant recipients, but appeared to not affect graft function. HCV infection was the most frequently associated etiology and clinical features were infrequent.

Hepatitis C virus, cryoglobulinaemia, and vasculitis: immune complex relations

Several viruses are involved in the development of systemic vasculitides. Hepatitis C virus (HCV) has been shown to be closely related to mixed cryoglobulinaemia, an immune complex-mediated vasculitis. HCV particles and non-enveloped nucleocapsid protein participate in the formation of immune complexes. Once formed, immune complexes precipitate in many organs, including the skin, kidneys, and peripheral nerve fibres. Viral proteins confer peculiar physical and chemical properties on cryoimmunoglobulins. Since expansion of rheumatoid factor-synthesising B cells is the biological hallmark of mixed cryoglobulinaemia, it may be that the combination of rheumatoid factor activity and cryoprecipitability is responsible for the vasculitis. B-cell clonal expansion occurs primarily in the liver and correlates with a high intrahepatic viral load, pointing to a major role for HCV in the emergence and maintenance of B-cell clonalities. Recognition of HCV as an aetiological factor in most cryoglobulinaemic vasculitides has dramatically changed the approach to their treatment. Emphasis, in fact, is now placed on abatement of the viral load and deletion of B-cell clonalities.

Pathogenic roles of B cells in human autoimmunity; insights from the clinic

The pathogenic roles of B cells in human autoimmune diseases involve a multitude of mechanistic pathways and include the well-established contributions of autoantibodies and immune complexes that induce local inflammatory reactions and tissue destruction. Recent results using several novel B cell-directed therapies have provided new insights into additional roles of B cells in human autoimmunity. In this review, we will highlight some of these studies and discuss how clinical insights parallel murine models of normal immunity and autoimmunity.