Enteral supplementation of alanyl-glutamine attenuates the up-regulation of beta-defensin-2 protein in lung injury induced by intestinal ischemia reperfusion in rats.

BACKGROUND: Beta-defensin-2 (BD-2), an endogenous antimicrobial peptide, plays a key role in immune response against microbial invasion. This study aimed to observe the effect of Alanyl-Glutamine (Ala-Gln) on BD-2 protein expression in pulmonary tissues after intestinal ischemia reperfusion (IIR) in rats and to investigate its correlations to pulmonary inflammatory and oxidative injury. METHODS: Rats in IIR and the two treatment groups were subjected to intestine ischemia for 60 min and those in the treatment groups were administered orally with Ala-Gln or alanine (Ala) respectively. Lung tissues were harvested to detect the BD-2 protein expression. Concentrations of Tumor necrosis factor (TNF)-α and malondialdehyde (MDA) as well as superoxide dismutase (SOD) activity in lung tissues were determined simultaneously. RESULTS: Ala-Gln attenuated the up-regulation of BD-2 expression (p < 0.05) and TNF-α (p < 0.05), MDA (p < 0.05) levels, as well as the reduction of SOD activity (p < 0.05) in lung tissues after IIR. But Ala did not exert significant effects. BD-2 protein in lung tissues was positively correlated to local TNF-α level (p < 0.01) and MDA concentration (p < 0.01) with statistical significance. CONCLUSION: Ala-Gln can relieve the IIR-induced up-regulation of BD-2 protein expression in the lung of rats, which involves anti-inflammation and anti-oxidation mechanisms.

Expression and localization of activin receptor-interacting protein 2 in mouse tissues.

Activin plays important roles in reproductive tissues as a stimulator of follicle-stimulating hormone (FSH) secretion. Activin receptor-interacting protein 2 (ARIP2) has been recently identified in mouse tissues as a regulatory protein of activin signal transduction. However, the localization and function of ARIP2 are not well characterized. In this study, we found that ARIP2 mRNA and protein were widely expressed in mouse tissues by reverse transcription-PCR (RT-PCR) and Western blotting. The immunoreactivities of ARIP2 were mainly localized at myocardial cells of heart, Leydig cells in testis, macrophages and epithelial cells of bronchus in lung, renal tubule and collecting tubule, pancreatic islet, adrenal gland, adenohypophysis and hypothalamus by immunohistochemical staining. Furthermore, ARIP2 overexpression down-regulated signal transduction induced by activin A in pituitary gonadotroph LbetaT2 cells and inhibited FSH secretion from primary cultured anterior pituitary cells induced by activin A. These findings suggest that ARIP2 is widely distributed in various tissues and may be a negative regulator of activin action in pituitary cells.