Fractalkine expression and the recruitment of CX₃CR1⁺ cells in the prolonged mesangial proliferative glomerulonephritis

Background. We established the reversible and the prolonged models of mesangial proliferative glomerulonephritis (GN) with anti-Thy 1 antibody 1-22-3. However, the essential factors leading to the prolonged glomerular alterations have not been identified. Methods. The expressions of several chemokines and cytokines were compared in the reversible and the prolonged models. Expression of fractalkine and the number of the fractalkine receptor CX₃CRl-positive cells in the glomeruli in the prolonged model were significantly higher than those in the reversible model. Then, the localization of fractalkine and the characteristics of CX₃CR1⁺ cells were analyzed in glomeruli. To elucidate the significance of the fractalkine expression, we analyzed the expression in the model treated with angiotensin II receptor antagonist, candesartan. Results. Immunostaining of fractalkine was detected on endothelial cells on the fifth day, and fractalkine staining also was detected in the mesangial area on day 14. Major parts of the CX₃CR1⁺ cells in the glomeruli were macrophages, especially ED3⁺ cells. Candesartan treatment ameliorated the glomerular morphological findings at six weeks after disease induction. Although the treatment did not ameliorate the morphological finding at two weeks, decreased expression of fractalkine and CX₃CR1⁺ were already detected at two weeks in rats treated with candesartan. Conclusions. Fractalkine expression and the recruitment of CX₃CR1⁺ cells in glomeruli might play an important role in the development of the prolonged disease. These expressions could be predictors of the prolonged disease of the mesangial proliferative glomerulonephritis.