Rheumatoid arthritis (RA) is a chronic joint disease characterized by leukocyte invasion and synoviocyte activation followed by cartilage and bone destruction. Its etiology and pathogenesis are poorly understood. We describe a spontaneous mouse model of this syndrome, generated fortuitously by crossing a T cell receptor (TCR) transgenic line with the NOD strain. All offspring develop a joint disease highly reminiscent of RA in man. The trigger for the murine disorder is chance recognition of a NOD-derived major histocompatibility complex (MHC) class II molecule by the transgenic TCR; progression to arthritis involves CD4+ T, B, and probably myeloid cells. Thus, a joint-specific disease need not arise from response to a joint-specific antigen but can be precipitated by a breakdown in general mechanisms of self-tolerance resulting in systemic self-reactivity. We suggest that human RA develops by an analogous mechanism.

Rheumatoid arthritis is a common and debilitating autoimmune disease whose cause and mechanism remain a mystery. We recently described a T cell receptor transgenic mouse model that spontaneously develops a disease with most of the clinical, histological, and immunological features of rheumatoid arthritis in humans. Disease development in K/BxN mice is initiated by systemic T cell self-reactivity; it requires T cells, as expected, but B cells are also needed, more surprisingly. Here, we have identified the role of B cells as the secretion of arthritogenic immunoglobulins. We suggest that a similar scenario may unfold in some other arthritis models and in human patients, beginning with pervasive T cell autoreactivity and ending in immunoglobulin-provoked joint destruction.

K/BxN T cell receptor transgenic mice are a model of inflammatory arthritis, similar to rheumatoid arthritis. Disease in these animals is focused specifically on the joints but stems from autoreactivity to a ubiquitously expressed antigen, glucose-6-phosphate isomerase (GPI). T and B cells are both required for disease initiation, but anti-GPI immunoglobulins (Igs), alone, can induce arthritis in lymphocyte-deficient recipients. Here, we show that the arthritogenic Igs act through both Fc receptors (in particular, FcgammaRIII) and the complement network (C5a). Surprisingly, the alternative pathway of complement activation is critical, while classical pathway components are entirely dispensable. We suggest that autoimmune disease, even one that is organ specific, can occur when mobilization of an adaptive immune response results in runaway activation of the innate response.

In spontaneous inflammatory arthritis of K/BxN T cell receptor transgenic mice, the effector phase of the disease is provoked by binding of immunoglobulins (Igs) to joint surfaces. Inflammatory cytokines are known to be involved in human inflammatory arthritis, in particular rheumatoid arthritis, although, overall, the pathogenetic mechanisms of the human affliction remain unclear. To explore the analogy between the K/BxN model and human patients, we assessed the role and relative importance of inflammatory cytokines in K/BxN joint inflammation by transferring arthritogenic serum into a panel of genetically deficient recipients. Interleukin (IL)-1 proved absolutely necessary. Tumor necrosis factor (TNF)–α was also required, although seemingly less critically than IL-1, because a proportion of TNF-α–deficient mice developed robust disease. There was no evidence for an important role for IL-6. Bone destruction and reconstruction were also examined. We found that all mice with strong inflammation exhibited the bone erosion and reconstruction phenomena typical of K/BxN arthritis, with no evidence of any particular requirement for TNFα for bone destruction. The variability in the requirement for TNF-α, reminiscent of that observed in treated rheumatoid arthritis patients, did not appear genetically programmed but related instead to subtle environmental changes.

The role of alcohol intake in the occurrence of severe liver disease in chronic hepatitis C virus (HCV) carriers is still debated. A cross-sectional study has been conducted in 233 chronic hepatitis C virus carriers. Weekly self-reported alcohol consumption (SRAC) was evaluated, serum HCV RNA levels were measured by a branched DNA technique (Quantiplex 2.0) and HCV genotypes were determined. A liver biopsy was performed simultaneously and liver lesions were graded with the Knodell histological activity index. Data were examined by uni-and multivariate analyses. Alcohol consumption was relatively low (F 140 g/per week in 193/233 patients [80%]). We found a highly significant correlation between SRAC and serum HCV RNA levels (r ‫؍‬ .26, P ‫؍‬ .001). Fibrosis was significantly correlated with age and alcohol consumption. These results suggest that in HCV carriers, alcohol consumption, even with low alcohol intake, increases viremia and hepatic fibrosis. Chronic HCV carriers should be advised to avoid regular alcohol intake. (HEPATOLOGY 1998;27:1717-1722.)The natural course of HCV infection is probably modulated by several cofactors. The role of virus-related factors, namely genotypes and viremia has been extensively studied 1-7 but still remains debated. 8 Up to now, immunological factors were underestimated but several arguments implicate the role of immune response in the course of the disease. Environmental factors and particularly alcohol intake are probably major factors, 9-10 and the increased severity of the disease and the faster occurrence of cirrhosis in patients with HCV infection and heavy alcohol intake has been suggested in several studies. [11][12] Moreover relations between alcohol and the immune response have been suggested with other viral infections. 13 The aim of the present study is to describe the effect of moderate alcohol intake on serum HCV RNA levels and histological liver lesions in patients with chronic HCV infection.