Anti-Collagen type III polyclonal antibody

Background and PurposeHypoxic activation of hypoxia-inducible factor 1 (HIF-1) and fibrosis in adipose tissue contribute to adipose dysfunction. This study was designed to investigate the effects of metformin and resveratrol on the regulation of HIF-1 and fibrosis in hypoxic adipose tissue. Experimental ApproachMice were fed a high-fat diet to induce hypoxia and fibrosis in adipose tissue; adipose tissue incubated in vitro in 1% O-2 showed a similar change. The effects of metformin and resveratrol on hypoxia, HIF-1 accumulation, endoplasmic reticulum stress and gene expressions of extracellular matrix components and pro-inflammatory cytokines were examined. Key ResultsOral administration of metformin or resveratrol prevented hypoxia and reduced HIF-1 accumulation with dephosphorylation of inositol-requiring enzyme 1 and eukaryotic initiation factor 2, indicative of suppression of hypoxic HIF-1 activation and endoplasmic reticulum stress. Metformin and resveratrol down-regulated gene expressions of Col3, Col6, elastin and lysyl oxidase and thereby reduced collagen deposition in adipose tissue. The increased gene expressions of TNF-, IL-6, monocyte chemoattractant protein 1 and F4/80 were also down-regulated by metformin and resveratrol. Metformin and resveratrol had similar effects in adipose tissue exposed to 1% O-2. Metformin reduced ATP production and prevented the reduction in oxygen tension in 3T3-L1 cells, suggesting that it prevented hypoxia by limiting oxygen consumption, whereas resveratrol reduced HIF-1 accumulation by promoting its proteasomal degradation via the regulation of AMPK/SIRT1. Conclusion and ImplicationsHypoxia and fibrosis are early causes of adipose dysfunction in obesity. Both metformin and resveratrol effectively inhibited HIF-1 activation-induced fibrosis and inflammation in adipose tissue, although by different mechanisms.

Rapamycin can inhibit fibroblast proliferation, collagen accumulation, and urethral stricture in rabbits. Transforming growth factor-beta-1 (TGF-/beta 1) signaling, with downstream recruitment of Smad2, is known to promote fibrosis. This in vitro study examined the effects of rapamycin on fibroblasts derived from human urethral scar tissue (FHUS) and investigated the possible mechanism with respect to regulation of TGF-beta 1 signaling. FHUS were cultured from urethral scar tissues collected from four patients with urethral stricture. The cells were exposed to different concentrations of rapamycin (0, 10, 20, 40, 80, or 160 ng/ml) for 24 or 48 hours. Cell growth was assessed by the MTT assay. Collagen content was measured based on hydroxyproline levels. The mRNA expressions of Smad2, eIF-4E, and alpha-1 chains of collagen types I and III (Col1 alpha 1 and Col3 alpha 1) were determined by semiquantitative reverse-transcription PCR. The protein expressions of Smad2, phospho-Smad2, and eIF-4E were evaluated by western blot. Rapamycin caused a concentration-dependent inhibition of FHUS growth at 24 and 48 hours (P < 0.01). Rapamycin decreased total collagen content (P < 0.01), collagen content per 10(5) cells (P < 0.05), and mRNA expressions of Col1 alpha 1 and Col3 alpha 1 (P < 0.05) in a concentration-dependent manner. Rapamycin elicited concentration-dependent reductions in the mRNA (P < 0.05) and protein (P < 0.01) expressions of Smad2 and elF-4E. The two highest concentrations of rapamycin also enhanced phospho-Smad2 levels (P < 0.01). In conclusion, the present study confirmed that rapamycin may reduce the growth and collagen production of FHUS, possibly through inhibition of TGF-/beta 1 signaling.