Biochemical and histological impact of direct renin inhibition by aliskiren on myofibroblasts activation and differentiation in bleomycin induced pulmonary fibrosis in adult mice.

Aliskiren is a drug classified as a direct renin inhibitor. The renin-angiotensin system plays an important role in pulmonary fibrogeneses. This study aimed to investigate the impact of aliskiren on pulmonary fibrosis induced by bleomycin. Forty adult mice were divided into group I (control), group II (aliskiren 25mg/kg/day IP), group III (bleomycin 0.035U/g intraperitoneally twice weekly for 4 weeks) and group IV (aliskiren+bleomycin). Plasma renin activity (PRA), lung content of hydroxyproline and transforming growth factor-ß1 (TGF-ß1) were assayed. Lung paraffin sections were prepared for histological study and immunohistochemical detection of alpha smooth muscle actin (αSMA) as a marker for myofibroblasts activation and differentiation. Bleomycin induced a significant elevation of PRA with a significant increase in hydroxyproline and TGF-ß1 in group III. Microscopically, pulmonary fibrosis was evident in the form of areas of collapsed alveoli, intense inflammatory cells infiltrations, excess accumulation of collagen, and excessively encountered αSMA positively immune-stained myofibroblasts, compared to a negative immune-reaction in groups I and II. In group IV, aliskiren resulted in a significant decrease in PRA, TGF-ß1 and hydroxyproline, with an attenuation of pulmonary fibrosis and a decrease in αSMA positively immune-stained myofibroblasts. In conclusion, renin inhibition by aliskiren attenuated pulmonary fibrosis through decreasing TGF-ß1 and myofibroblasts activation and differentiation.

Effect of alpha lipoic acid co-administration on structural and immunohistochemical changes in subcutaneous tissue of anterior abdominal wall of adult male albino rat in response to polypropylene mesh implantation.

Polypropylene mesh is commonly used in the treatment of abdominal hernia. Different approaches were addressed to improve their tissue integration and consequently reduce long-term complications. This study aimed to investigate the effect of alpha-lipoic acid (ALA) co-administration on structural and immunohistochemical (IHC) changes in the subcutaneous tissues of the anterior abdominal wall of the adult rat in response to polypropylene mesh implantation. Forty adult male albino rats were divided into: group I (control), group II (receiving ALA), group III (polypropylene mesh implantation) and group IV (mesh implantation + ALA co-administration). After 4 weeks, subcutaneous tissue samples were prepared for light microscopy and IHC study of CD34 as a marker for angiogenesis. In groups I and II rats, positive CD34 expression was demonstrated by IHC reaction, localized to endothelial cells lining small blood vessels. Group III showed an excess inflammatory reaction, deposition of both regular and irregularly arranged collagen fibres around mesh pores and few elastic fibres. CD34-positive was detected not only in cells lining small blood vessels but also in other cells scattered in the connective tissue indicating angiogenesis. In group IV, ALA co-administration resulted in less inflammatory reaction, regular collagen deposition, enhanced elastic fibres synthesis and a significant increase in CD34-positive cells and small blood vessels reflecting improved angiogenesis. ALA co-administration with polypropylene mesh implantation controlled the inflammatory reaction, helped regular collagen deposition, enhanced elastic fibres synthesis and improved angiogenesis in the subcutaneous tissue of anterior abdominal wall of adult albino rats, suggesting a possible role of ALA in optimizing mesh integration in subcutaneous tissue.