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Objective: To examine whether chemokine antagonists inhibit the initiation and progression of lupus nephritis in MRL/lpr mice., Methods: NH(2)-terminal-truncated monocyte chemoattractant protein 1 (MCP-1)/CCL2 or thymus and activation-regulated chemokine (TARC)/CCL17 analogs were inserted into the pCXN2 expression vector and transfected into a nonmetastatic fibroblastoid cell line, MRL/N-1, established from an MRL/gld mouse., Results: MCP-1 antagonist- or TARC antagonist-transfected MRL/N-1 cells were injected subcutaneously into MRL/lpr mice ages 7 weeks (before the onset of lupus nephritis) and 12 weeks (at the early stage of the disease). After 8 weeks, mice bearing the MCP-1 antagonist showed markedly diminished infiltration of macrophages and T cells, glomerular hypercellularity, glomerulosclerosis, crescent formation, and vasculitis compared with control mice. This seemed to be due to decreased production of interferon-gamma and interleukin-2 in the kidney. In contrast, there was no significant difference in renal damage between mice bearing TARC antagonist and control mice., Conclusion: We established a new system using MRL/N-1 cells that allows long-term observation of the effects of chemokine antagonists on lupus nephritis in MRL/lpr mice. We also showed that the MCP-1 antagonist ameliorated the initiation and progression of lupus nephritis and of renal vasculitis, which might provide a new approach to the treatment of the disease.

Objective: To clarify the mode of inheritance of the tissue distribution of vasculitis in MRL/Mp-lpr/lpr (MRL/lpr) lupus-prone mice and to identify the susceptibility loci., Methods: Vasculitis in individual MRL/lpr, C3H/HeJ-lpr/lpr (C3H/lpr), (MRL/lpr x C3H/lpr)F(1), and (MRL/lpr x C3H/lpr)F(2) intercross mice was analyzed by histopathologic grading of main branches of the aorta and of medium-sized arteries in the lower limbs. Genomic DNA samples from F(2) intercross mice were examined by simple sequence-length polymorphism analysis, and the polymorphic microsatellite markers highly associated with vasculitis in each tissue were determined as vasculitis susceptibility loci., Results: A susceptibility locus with significant linkage to vasculitis of main branches of the aorta was mapped on chromosome 4 at D4Mit213 (map position 13.3cM) selectively in males, while vasculitis of medium-sized arteries in the lower limbs was mapped to different chromosomes: at D8Mit31 on chromosome 8 (map position 33.0) selectively in females and at D5Mit36 on chromosome 5 (map position 65.0). All of these were different from the previously defined loci governing susceptibility to vasculitis involving the kidneys., Conclusion: Systemic vasculitis in MRL/lpr mice is genetically controlled with cumulative effects of multiple gene loci, each of which has tissue specificity.

Almost all of intractable vasculitis have been thought to develop mainly in immunological mechanisms, based on the data from several animal models previously established. Serum sickness models, microbe-induced models and others have contributed to supporting this idea. These models have furthermore indicated that vasculitis could be generated by exogenous factors in normal individuals, and that vasculitis might be explained in monism. However, recent studies in murine lupus suggest that intractable vasculitis requires endogenous factors involving retroviruses and/or genetic background under the control of polygene system. In this review, although not comprehensive, significance of background genes in vasculitis will be focused.