ABSTRACT

Mixed cryoglobulinemia (MC) is a lymphoproliferative disorder observed in ∼10 to 15% of hepatitis C virus (HCV)-infected patients. Circulating, nonenveloped HCV core protein, which has been detected in cryoprecipitable immune complexes, interacts with immunocytes through the receptor for the globular domain of C1q protein (gC1q-R). In this study, we have evaluated circulating gC1q-R levels in chronically HCV-infected patients, with and without MC. These levels were significantly higher in MC patients than in those without MC and in healthy controls and paralleled specific mRNA expression in PBL. Soluble gC1q-R circulates as a complexed form containing both C1q and HCV core proteins. Higher serum gC1q-R levels negatively correlated with circulating concentrations of the C4d fragment. The presence of sequestered C4d in the vascular bed of skin biopsies from MC patients was indicative of in situ complement activation. In vitro studies showed that release of soluble gC1q-R is regulated by HCV core-mediated inhibition of cell proliferation. Our results indicate that up-regulation of gC1q-R expression is a distinctive feature of MC, and that dysregulated shedding of C1q-R molecules contributes to vascular cryoglobulin-induced damage via the classic complement-mediated pathway.

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.

Chemokine CXCL13, also known as BCA-1 (B cell-attracting chemokine-1) or BLC (B-lymphocyte chemoattractant), is a major regulator of B-cell trafficking. Hepatitis C virus (HCV) infection may be associated with B-cell dysfunction and lymphoproliferative disorders, including mixed cryoglobulinemia (MC). This study evaluates circulating levels of CXCL13 protein and specific mRNA expression in chronically HCV-infected patients with and without MC. Compared with healthy controls and HCV-infected patients without MC, CXCL13 serum levels were significantly higher in MC patients. The highest CXCL13 levels strongly correlated with active cutaneous vasculitis. CXCL13 gene expression in portal tracts, isolated from liver biopsy tissues with laser capture microdissection, showed enhanced levels of specific mRNA in MC patients with active cutaneous vasculitis. Specific CXCL13 gene mRNA expression was also up-regulated in skin tissue of these patients. These findings paralleled specific deposits of CXCL13 protein both in the liver and in the skin. Our results indicate that up-regulation of CXCL13 gene expression is a distinctive feature of HCVinfected patients. Higher levels of this chemokine in the liver as well as in the skin of patients with active MC vasculitis suggest a possible interrelation between these biologic compartments. (Blood. 2008;112:1620-1627) IntroductionChronic active liver disease (CALD) is an inflammatory disorder recognizing several etiologies and different pathogenetic mechanisms. 1 Within inflamed liver, there is an accumulation of lymphoid and myeloid cells, including T and B cells. 2 Local activation of these cells is thought to be essential in perpetuating the chronic inflammatory process and accelerating liver damage. 3 T and B cells in CALD frequently accumulate in the portal tracts and organize follicle-like structures, with features of germinal centers (GCs). 4 In these sites, local differentiation of follicular dendritic cells, plasma cells, and antibody production may occur. 5 In hepatitis C virus (HCV) infection, distinct B-cell expansions contribute to the formation of intraportal follicle-like structures. 6,7 Circulating B-cell clonotypes have been suggested to be of hepatic origin, indicating that IgH VDJ mutational activity is up-regulated in the hepatic microenvironment. 8 Sequence analyses of IgH CDR-3 gene segments of intraportal B-cell clonalities have revealed a wide range of variations, possibly implying that they are the result of an antigen-driven response. 9 The occurrence of B-cell clonal expansions in the liver of HCV-infected patients has been found to deeply influence the clinical picture, which appears to be strictly related to mixed cryoglobulinemia (MC) and, in general, to lymphoproliferative stigmata, including high serum levels of rheumatoid factor (RF) and monoclonal gammopathy of undetermined significance. 8 The relationship between emergence and persistence of intrahepatic or circulating B-cell clonotypes and HCV infection is still unknown. Accumulating evidence indi...

We evaluated the influence of cryoglobulinemic syndrome (CS) on the outcome of chronic hepatitis C virus (HCV) infection in a 15-year prospective study. We assessed a cohort of 950 chronically HCV-infected patients, collected from the beginning of 1990 to the end of 2010. All patients had received a liver histologic diagnosis. Mixed cryoglobulinemia (MC) was determined in 246 patients (25.8%), of whom 184 also had CS. They were assessed every 3 months for 15 years, at least; 141 patients with CS and 601 without MC completed the study.No spontaneous clearance of cryoglobulins was noted. Type II to type III spontaneous switching was ascertained in 1.6% (0.08%/yr) patients. The estimated progression rate of liver fibrosis was lower in CS(+) than in MC(−) patients (p < 0.05). The 15-year cumulative probability of developing cirrhosis and/or hepatocellular carcinoma was higher in MC(−) than in CS(+) patients (24.9% vs. 14.2%, p < 0.005 and 20.3% vs. 7.5%, p = 0.003, respectively). Renal insufficiency, neurologic impairment, or B-cell non-Hodgkin lymphoma were significantly more frequent in CS(+) than in MC(−) patients (32.6% vs. 3%, p < 0.0001; 31.2% vs. 4.8%, p < 0.0001; and 15% vs. 7.1%, p = 0.003, respectively). However, in spite of different morbidity features and causes of death, the 15-year survival rate was similar in the 2 groups (70.2% vs. 71.7%). Antiviral therapy had an undisputable impact on patient outcome.This 15-year prospective cohort study shows that, although CS has no influence on the overall survival of HCV-infected patients, it significantly modifies the natural history of chronically HCV-infected patients.