C Ramírez

Role of Intrarenal Endothelin 1, Endothelin 3, and Angiotensin II Expression in Chronic Cyclosporin A Nephrotoxicity in Rats

Endothelin 1 (Et1) is widely expressed in the kidney and is related to several functions and to pathological conditions with progression towards sclerosis. The function of endothelin 3 (Et3) at the renal level is debatable, but it could have an important regulatory function in the reabsorption of water through its action on tubular type B receptors. Angiotensin II has recently been implicated as the principal factor responsible for the progression of interstitial fibrosis induced by cyclosporin A (CsA). We investigated this relationship in vivo and analyzed the modifications induced by CsA toxicity in Sprague-Dawley rats treated with 25 mg/kg/day of CsA for 28 and 56 days. Immunohistochemical methods and molecular analysis were used to study the expression of Et1 and Et3 and immunohistochemistry alone to determine the intrarenal expression of angiotensin II. Rats treated with CsA developed chronic nephrotoxicity lesions; semiquantitative analyses of hyaline arteriolopathy revealed that the passage of time affected the extent of this lesion and led to the diminution of the total glomerular area. Immunohistochemical results showed that chronic CsA treatment induced moderate secretion of Et1 and Et3 at tubular and glomerular levels and that the local expression of angiotensin II in the treatment groups was more evident than in control animals. Besides, the mRNA levels of preproEt3 showed a dramatic increase from 28 days after CsA treatment (control group 0.07 ± 0.11 vs. CsA group 0.48 ± 0.11, p < 0.01), while the mRNA levels of preproEt1 increased from 56 days (control group 0.15 ± 0.05 vs. CsA group 0.34 ± 0.09, p < 0.05). At 28 days, renal lesions correlated strongly with the mRNA levels of Et3 (r > 0.50, p < 0.01). However, at 56 days, the key finding was the strong correlation of the most important analytical, histological, and immunohistochemical parameters of CsA nephrotoxicity with Et1 mRNA levels (r > 0.50, p < 0.01). These results support the hypothesis that the clinical and morphological phenomena linked with CsA nephrotoxicity are related to hypersecretion of endothelins and local expression of angiotensin II in the outer medulla and medullary rays; Et3 and angiotensin II are the first to act, followed subsequently by Et1.

Influence of intrarenal deposits of ciclosporin A on acute renal transplant rejection.

Immunohistochemical techniques were used to study the presence of ciclosporin A (CsA) and leukocyte subsets in 36 posttransplant renal biopsy specimens histologically diagnosed as acute graft rejection. Glomeruli from patients with CsA deposits contained more leukocytes (p < 0.05) than glomeruli from tissues without deposits. In contrast, the interstitium from patients without deposits contained significantly more B lymphocytes than interstitia from kidneys with CsA deposits. In both glomeruli and interstitia, the CD4/CD8 ratios were higher in tissues without deposits, although the difference was not significant. The plasma levels of creatinine increased with the intensity of renal CsA deposits, and significantly more patients on hemodialysis had deposits as compared with patients not on hemodialysis. Our findings suggest two types of acute nonvascular rejection: (1) predominantly interstitial, with a good prognosis, characterized by low numbers of intrarenal CsA deposits and a predominance of B lymphocytes and (2) predominantly glomerular, with a poor prognosis, characterized by high levels of intrarenal CsA and a predominance of CD8-positive cells and macrophages.