Collagen metabolism in fibrotic liver. Effects of concanavalin A and aggregated myeloma immunoglobin G

Cathepsin-D, adiponectin, TNF-α, IL-6 and hsCRP plasma levels in subjects with diabetic foot and possible correlation with clinical variables: a multicentric study

Diabetic foot, characterized by a pronounced inflammatory reaction, decreased collagen content and biosynthesis and accelerated degradation are crucial in wound healing. Cathepsin D, an aspartic endopeptidases implicated in cell growth, apoptosis, and its inhibitor has been reported to reverse the inhibition of collagen biosynthesis in wounded rat skin with diabetes. To date, the increased proteolytic activity of Cathepsin D in diabetic foot has not been evaluated and the pathogenic significance of the inflammation has received little attention. Of the patients [with ulcer (n=211) and without ulcer (n=208)], 89.73% had type 2 diabetes. Subjects with diabetic foot ulcer showed higher median plasma level of Cathepsin D [556.3 (312.6-587.3) RFC/ml vs 306.3 (92.6-337.3) RFC/ml], TNF-α [96.6 (79.9-121.5) ng/ml vs 8.4 (7.1-9.20) ng/ml], IL-6 [32.2 (8.52-48.4) ng/ml vs 4.9 (4.5-5.6) ng/ml], hsCRP [12.6 (11.2-14.1) mg/ml vs 3.90 (3.50-4.60) mg/ml] and lower median plasma levels of adiponectin [8.50 (7.10-9.5) ng/ml vs 13.3 (12.1-14.2) ng/ml]. A positive correlation was found between grades of ulcer, BMI, A1c and retinopathy for Cathepsin D, for adiponectin, between grades of ulcer, BMI, retinopathy, nephropathy & smoking, for IL-6, between grades of ulcer, BMI, nephropathy, CAD & smoking, for hsCRP, grades of ulcer, BMI, LDL-C, nephropathy & smoking, while total cholesterol, nephropathy, PAD, smoking and neuropathy for TNF-α.

Stabilization of type I collagen against collagenases (type I) and thermal degradation using iron complex

The widespread application of collagen as a biomaterial warrants research in understanding the stabilization of the same. In this study, interaction of iron-tetrakis (hydroxymethyl) phosphonium (THP) complex with type I collagen has been investigated. DSC and hydrothermal measurement studies reveal that the shrinkage temperature of iron-THP treated rat tail tendon (RTT) collagen is 33 degrees C higher than that of native RTT collagen. Fe-THP complex also brings about high degree of enzymatic stability to type I collagen. The effect of Fe-THP on the conformation of collagen was studied using circular dichroism and it was found that no major alterations in the triple helical structure of collagen occur on treatment with Fe-THP. It is observed from viscosity experiment results that though Fe-THP complex is able to bring about long range ordering of collagen, as evident from the thermal and enzymatic stability imparted to collagen, this ordering does not lead to any aggregation of collagen. Since THPS is reducing in nature, it is expected to keep iron in the +2 state and if THP chelates to Fe(II), the hydrolytic behavior of iron can also be controlled.

RNA interference targeting Fas protects mice from fulminant hepatitis

RNA interference (RNAi) is a powerful tool to silence gene expression post-transcriptionally. However, its potential to treat or prevent disease remains unproven. Fas-mediated apoptosis is implicated in a broad spectrum of liver diseases, where inhibiting hepatocyte death is life-saving. We investigated the in vivo silencing effect of small interfering RNA (siRNA) duplexes targeting the gene Fas (also known as Tnfrsf6), encoding the Fas receptor, to protect mice from liver failure and fibrosis in two models of autoimmune hepatitis. Intravenous injection of Fas siRNA specifically reduced Fas mRNA levels and expression of Fas protein in mouse hepatocytes, and the effects persisted without diminution for 10 days. Hepatocytes isolated from mice treated with Fas siRNA were resistant to apoptosis when exposed to Fas-specific antibody or co-cultured with concanavalin A (ConA)-stimulated hepatic mononuclear cells. Treatment with Fas siRNA 2 days before ConA challenge abrogated hepatocyte necrosis and inflammatory infiltration and markedly reduced serum concentrations of transaminases. Administering Fas siRNA beginning one week after initiating weekly ConA injections protected mice from liver fibrosis. In a more fulminant hepatitis induced by injecting agonistic Fas-specific antibody, 82% of mice treated with siRNA that effectively silenced Fas survived for 10 days of observation, whereas all control mice died within 3 days. Silencing Fas expression with RNAi holds therapeutic promise to prevent liver injury by protecting hepatocytes from cytotoxicity.

Active and latent collagenase activity during reversal of hepatic fibrosis in murine schistosomiasis

In schistosomiasis mansoni, eggs trapped in portal venules of the liver induce a granulomatous inflammatory reaction and subsequently fibrosis. Upon specific schistosomicidal treatment, however, fibrosis undergoes a marked reversal. The features of this process as regards collagen metabolism were examined in mice using praziquantel as the schistosomicidal drug, which was given 68 days after infection. It was found that collagenase activity in the liver, for both latent and active forms, increases rapidly until 5 days after treatment as compared to nontreated infected mice and then diminishes gradually. The hydroxyproline content in liver and (24-hr) urine are also modified, their values decreasing progressively up to 72 days after treatment without, however, reaching values observed in normal mice. Worm death appears to be the triggering stimulus of these events.