Effects of systemic inflammation due to hepatic ischemia-reperfusion injury upon lean or obese visceral adipose tissue

Purpose: To evaluate how the induction of liver damage by ischemia and reperfusion affects the adipose tissue of lean and obese mice. Methods: Lean and diet-induced obese mice were subjected to liver ischemia (30 min) followed by 6 h of reperfusion. The vascular stromal fraction of visceral adipose tissue was analyzed by cytometry, and gene expression was evaluated by an Array assay and by RT-qPCR. Intestinal permeability was assessed by oral administration of fluorescein isothiocyanate (FITC)-dextran and endotoxemia by serum endotoxin measurements using a limulus amebocyte lysate assay. Results: It was found that, after liver ischemia and reperfusion, there is an infiltration of neutrophils, monocytes, and lymphocytes, as well as an increase in the gene expression that encode cytokines, chemokines and their receptors in the visceral adipose tissue of lean mice. This inflammatory response was associated with the presence of endotoxemia in lean mice. However, these changes were not observed in the visceral adipose tissue of obese mice. Conclusions: Liver ischemia and reperfusion induce an acute inflammatory response in adipose tissue of lean mice characterized by an intense chemokine induction and leukocyte infiltration; however, inflammatory alterations are already present at baseline in the obese adipose tissue and liver ischemia and reperfusion do not injure further.

The importance of oxygen free radicals in the etiopathogenesis of diversion colitis in rats / A importância dos radicais livres de oxigênio na etiopatogenia da colite de exclusão em ratos

PURPOSE: Quantify the levels of oxidative DNA damage of epithelial colon cells comparing segments with and without fecal stream. METHODS: Sixty Wistar rats were subjected to deviation of fecal stream by proximal colostomy and a distal mucosal fistula. Animals were divided into three experimental groups that were sacrificed 6, 12 and 24 weeks after surgery. In each experimental group, five animals underwent laparotomy without intestinal deviation (sham subgroup). The diagnosis of colitis was made by histopathological analysis and the inflammatory activity index by graduated scale. The neutrophil infiltration was determined by myeloperoxidase tissue levels and the intensity of oxidative DNA damage by comet assay. The Mann-Withney and Student t test were used to compare the results among experimental subgroups and the Kruskal-Wallis test for variance analysis, adopting a significance level of 5 percent (p<0.05). RESULTS: Colon segments without fecal stream was shown higher histological inflammatory score of the colon wall after 12 and 24 weeks (p=0.001) that increased with the time of diversion (p=0.01). The activity of myeloperoxidase in segments without fecal stream decreased with the time (p=0.001). Oxidative DNA damage levels were significantly higher in the segments without fecal stream, (p=0.0001), independent of time of colon diversion, and increase with the time (p=0.0007). CONCLUSIONS: Colon segments without fecal stream showed high levels of oxidative DNA damage related to histological alterations observed in diversion colitis. The levels of oxidative DNA damage in segments devoid of the fecal stream increase with the time of intestinal exclusion.(AU)

OBJETIVO: Quantificar os níveis de dano oxidativo ao DNA em células epiteliais da mucosa cólica comparando segmentos com e sem trânsito fecal. MÉTODOS: Sessenta ratos Wistar foram submetidos à derivação do trânsito intestinal por colostomia proximal e fístula mucosa distal. Os animais foram divididos em três grupos experimentais segundo terem sido sacrificados 6, 12 e 24 semanas após a cirurgia. Em cada grupo experimental, cinco animais foram submetidos à laparotomia isolada sem derivação fecal (grupo sham). O diagnóstico de colite foi estabelecido por análise histopatológica e o índice de atividade inflamatória por escala graduada. A infiltração neutrofílica foi determinada pelos níveis teciduais da mieloperoxidase e a intensidade do dano oxidativo ao DNA pelo ensaio em cometa. Utilizaram-se os testes de Mann-Withney e o teste t de Student para comparar os resultados encontrados entre os subgrupos experimentais e o teste de Kruskal-Wallis para análise de variância, adotando-se nível de significância de 5 por cento (p<0,05). RESULTADOS: Os segmentos cólicos, sem trânsito fecal apresentaram maior escore histológico de inflamação após 12 e 24 semanas (p=0,001), que aumentou com o tempo de derivação (p=0,01). A atividade da mieloperoxidase nos segmentos sem trânsito fecal diminuiu com o progredir do tempo (p=0,001). Os níveis de dano oxidativo ao DNA foram significativamente maiores nos segmentos sem trânsito fecal (p=0,0001), independente do tempo de exclusão considerado, aumentando com o progredir do tempo de exclusão (p = 0,0007). CONCLUSÕES: Segmentos cólicos desprovidos de trânsito fecal apresentam níveis elevados de dano oxidativo ao DNA relacionados às alterações histológicas observadas na colite de exclusão. Os níveis de dano oxidativo ao DNA nos segmentos desprovidos de trânsito fecal aumentam com o decorrer do tempo de exclusão.(AU)