Transcriptional profiling of PBMCs unravels B cell mediated immunopathogenic imprints of HCV vasculitis.

B cell depletion therapy using rituximab has been shown to be effective in achieving remission in patients with HCV-mixed cryoglobulinemic (MC) vasculitis. Previously, we have demonstrated abnormalities in peripheral immune cells involving neutrophils, chemotaxis, and innate immune activation among patients with HCV-MC vasculitis when compared to HCV patients without vasculitis. In this study, we evaluated the effect of B cell depletion therapy on transcriptional profiles of peripheral blood mononuclear cells before and after riruximab therapy, in order to unravel the pathogenic mechanism involved in HCV-MC vasculitis induced by abnormal B cell proliferation. DNA microarray analysis was performed using RNA from PBMCs from seven patients with HCV-MC vasculitis and seven normal volunteers. DNA was hybridized to Affymetrix U133A chips. After normalization, differentially expressed gene list with treatment was generated using partitional clustering. RT-PCR, flow cytometry, and enzyme immunoassay (EIA) was used to validate DNA microarray findings. Differentially expressed genes included B cells and non-B cell genes. Validation of genes using purified cell subsets demonstrated distinct effect of B cell depletion therapy on non-B cells, such as monocytes, T cells, and NK cells. Notably, B lymphocyte stimulator (BLyS) levels were persistently elevated in patients who subsequently relapsed. In conclusion, pathogenesis of HCV-MC vasculitis is mediated by abnormal proliferation of B cells, driven by BLyS, leading to significant effects on non-B cells in mediating symptomatology. Future therapeutics using a combination approach of B cell depletion and proliferation may be desired to achieve long-term remission

Hepatitis C-Associated Mixed Cyroglobulinemic Vasculitis Induces Differential Gene Expression in Peripheral Mononuclear Cells

This study examines the distinct gene expression profile of peripheral blood mononuclear cells from patients with chronic hepatitis C (CHC) infection and mixed cryoglobulinemic (MC) vasculitis. Our DNA microarray analysis indicates that HCV-associated MC vasculitis is characterized by compromised neutrophil function, impaired chemotaxis, and increased interferon stimulated gene (ISG) expression, contributing to overall MC pathogenesis and end organ damage. Increased ISG expression is suggestive of an enhanced endogenous interferon gene signature. PBMC depletion assays demonstrate that this increased expression is due to an activation of monocytes and not a direct result of B cell expansion. Notably, this monocyte activation of ISG expression in HCV-associated MC vasculitis suggests a poor predictor status of interferon-based treatment. Further analysis of PBMC gene expression profiles before and after in vivo B cell depletion therapy is critical to completely understanding the mechanisms of MC vasculitis pathogenesis

FDA-FRNA50-07MAR17_plos

Operetta and chemiluminescent raw dat