Diabetes mellitus complicates pregnancies, leading to diseases in adult life in the offspring. Asymmetric dimethylarginine (ADMA) is increased in diabetes mellitus, kidney disease, and hypertension. We tested whether maternal diabetes causes increased ADMA in rats, resulting in kidney disease and hypertension in the adult offspring, and whether these can be prevented by maternal citrulline supplementation. Newborn female and pregnant Sprague-Dawley rats were injected with streptozotocin (STZ), which made up the nSTZ and STZ models, respectively. For the STZ model, 4 groups of male offspring were killed at age 3 months: the control, STZ, and Cit and STZ+Cit (control and STZ rats treated with 0.25% l-citrulline solution, respectively) groups. The nSTZ rats had lower nephron numbers. The renal level of ADMA was higher in the nSTZ rats than in controls. The STZ group developed kidney injury, renal hypertrophy, and elevated blood pressure at the age of 12 weeks. These conditions were found to be associated with increased ADMA levels, decreased nitric oxide (NO) production, and decreased dimethylarginine dimethylaminohydrolase (DDAH) activity in the kidney. In addition, ADMA caused a nephron deficit in cultured rat metanephroi. Maternal citrulline supplementation prevented hypertension and kidney injury, increased the renal DDAH-2 protein level, and restored the levels of ADMA and NO in the STZ+Cit group. Reduced nephron number and increased ADMA contribute to adult kidney disease and hypertension in offspring of mothers with STZ-induced diabetes. Manipulation of the ADMA-NO pathway by citrulline supplementation may be a potential approach to prevent these conditions.

Inflammatory processes can stimulate renal epithelial cells to release cytokines, chemoattractants and matrix proteins into the interstitium, thus contributing to interstitial injury during acute allograft rejection. To test the role of interleukin 17 (IL-17) in this process, cultured human renal epithelial cells (hRECs) were first established and treated with or without human IL-17 (hIL-17) for 2, 4, 8 and 10 h in vitro. Significant elevations of IL-6 and IL-8 levels were noted in the supernatants in a dose-dependent and time-dependent manner, as also for IL-6 mRNA expression. Secondly, using a rat acute allograft rejection model, the correlation between IL-17 expression and histopathological changes was serially studied. The results demonstrated that increased expression of IL-17 protein on infiltrating mononuclear cells (MNCs) was detectable on day 2. This corresponds to the borderline change of acute rejection according to the Banff classification, and it increased progressively to day 5. Serial study of IL-6, IL-8 and IL-17 mRNA expression of the renal allograft confirmed IL-17 mRNA expression in the allograft early on post-transplant day 2, whereas IL-6 and IL-8 expression started on day 3. Thirdly, IL-17 expression was observed in human renal allograft and urinary sediment. IL-17 protein expression was found in human subclinical (borderline) rejection renal allograft biopsy tissue and none in biopsy tissue not showing any evidence of rejection. There was also a 100% detectable rate of IL-17 mRNA expression in the MNCs of urinary sediment of patients with subclinical borderline rejection. These results demonstrate that hRECs exposed to IL-17 can produce inflammatory mediators with the potential to stimulate early alloimmune responses, which may also serve to give warning of acute renal allograft rejection.

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