Résumé
BACKGROUND AND AIMS: Obesity is an important risk factor for chronic kidney disease (CKD). It carries hemodynamic and morphologic changes in the kidney resulting in renal function reduction. CKD is associated with glomerulosclerosis and tubulointerstitial fibrosis that involve collagen deposition. The aim of the study was to evaluate the impact of obesity on kidney fibrosis in a model of 5/6th nephrectomized rats fed a cafeteria diet.METHOD: Twenty four rats were fed acafeteria diet and 10 rats received a standard diet for 6 months. For each diet group, half of the rats underwent 5/6 nephrectomy (SNx) at 4 months. Expression of collagen type 1, 3, 4 was quantified by immunohistochemistry in kidney sections at 6 months. Adipocyte size was measured in epididymal adipose tissue (eWAT), and the presence of macrophages was determined by CD68 immunostaining.RESULTS: Rats fed the cafeteria diet were hyperglycemic and hypertensive. Their body weight was higher than those fed the standard diet. SNx rats had increased serum creatinine levels, which were even higher in the cafeteria group (71 ± 10 µM) compared with standard diet group (54 ± 5 µM) (P < 0.05). Serum creatinine level was comparable in non-nephrectomized animals fed the cafeteria (32 ± 1 µM) or standard diet (29 ± 1 µM). Collagen 1 level in kidney tissue was increased in both SNx groups with no clear effect of the diet (respectively, 7.1 ± 0.6% and 8.9 ± 0.9% of tissue area with the standard and cafeteria diets). Renal expression of collagen 3 and 4 was significantly increased in SNx animals with cafeteria diet (8.6 ± 1.5 and 10.9 ± 1.9% tissue area, respectively) compared with control rats fed the same diet (5.2 ± 0.5 and 6.3 ± 0.6% tissue area, respectively). Adipocyte size of eWAT was significantly increased by cafeteria diet but reduced in nephrectomized rats. In the cafeteria-SNx group, CD68 immunostaining showed a significant increase in macrophage number in kidney (P = 0.01) and a consistent tendency in eWAT.