Damon Bevan

Diverse and potent activities of HGF/SF in skin wound repair†

Genetic studies in the mouse have highlighted essential roles for several growth factors in skin repair and have offered a rationale for their use in therapy. The present study shows that the plasminogen‐related growth factor HGF/SF (hepatocyte growth factor/scatter factor) promotes wound repair in homozygous diabetic db/db mice by recruiting neutrophils, monocytes, and mast cells to the wound; by promoting the migration of endothelial cells to the injured area; and by enhancing keratinocyte migration and proliferation. As a result, granulation tissue formation, wound angiogenesis, and re‐epithelialization are all increased. The results demonstrate that HGF/SF affects and sustains all key cellular processes responsible for wound repair and point to a unique potential of this molecule for the therapy of chronic skin wounds. Copyright

Dual regulation of metalloproteinase expression in chondrocytes by Wnt-1–inducible signaling pathway protein 3/CCN6

OBJECTIVE Wnt-1-inducible signaling pathway protein 3 (WISP-3)/CCN6 is mutated in progressive pseudorheumatoid dysplasia and may have effects on cartilage homeostasis. The aim of this study was to ascertain additional roles for WISP-3/CCN6 by determining its expression in osteoarthritic (OA) cartilage and by investigating its effects on cartilage-relevant metalloproteinase expression in immortalized (C-28/I2) and primary chondrocytes. METHODS Cartilage steady-state levels of WISP-3/CCN6 messenger RNA and protein production were determined by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry, respectively. WISP-3/CCN6 was overexpressed in C-28/I2 cells, and the resultant clones were analyzed by quantitative RT-PCR. The stable clones were analyzed by RT-PCR for metalloproteinase expression, and the signaling pathways involved were investigated using pharmacologic inhibition. The effects of WISP-3/CCN6 on metalloproteinase expression in primary chondrocytes were investigated using a small interfering RNA approach. RESULTS WISP-3/CCN6 was highly expressed in OA cartilage compared with undamaged cartilage, at both the RNA and protein levels. WISP-3/CCN6 overexpression in C-28/I2 cells resulted in unexpected dual regulation of metalloproteinases; expression of the potent aggrecanase ADAMTS-5 was down-regulated 9-fold, while expression of MMP-10 was up-regulated 14-fold, and these responses were accentuated in the WISP-3/CCN6 clones grown in suspension. MMP-10 up-regulation was dependent on several MAPKs, but WISP-3/CCN6-mediated ADAMTS-5 repression was independent of these pathways and was partially relieved by activation of β-catenin signaling. WISP-3/CCN6 also suppressed ADAMTS-5 expression in C-28/I2 cells treated with cytokines. In cytokine-treated primary chondrocytes, gene silencing of WISP-3/CCN6 resulted in enhanced ADAMTS-5 expression, while MMP-10 expression was suppressed. CONCLUSION WISP-3/CCN6 was highly expressed in end-stage OA cartilage, suggesting a role for this growth factor in cartilage homeostasis. WISP-3/CCN6-induced repression of ADAMTS-5 expression and regulation of MMP-10 expression suggest complex and context-dependent roles for WISP-3/CCN6 in cartilage biology.

N-3 fatty acids combined with flavan-3-ols prevent steatosis and liver injury in a murine model of NAFLD

Non-alcoholic fatty liver disease (NAFLD) affects 25% of adults and at present no licensed medication has been approved. Despite its complex patho-physiology, dietary strategies aiming at delaying or preventing NAFLD have taken a reductionist approach, examining the impact of single components. Accumulating evidence suggests that n-3 LC-PUFAs are efficacious in regulating lipogenesis and fatty acid oxidation. In addition, plant derived flavonoids are also emerging as a dietary strategy for NAFLD prevention, with efficacy attributed to their insulin sensitising and indirect antioxidant effects. Based on knowledge of their complementary molecular targets, we aimed to demonstrate that the combination of n-3 LC-PUFA (n-3) and flavan-3-ols (FLAV) prevents NAFLD. In a high-fat high-fructose (HF/HFr) fed C57Bl/6J mouse model, the independent and interactive impact of n-3 and FLAV on histologically defined NAFLD, insulin sensitivity, weight gain, intestinal and hepatic gene expression, intestinal bile acids were examined. Only the combination of FLAV and n-3 (FLAVn-3) prevented steatosis as evidenced by a strong reduction in hepatocyte ballooning. While FLAV reduced body (-28-30%), adipose tissue (-45-50%) weights and serum insulin (-22-25%) as observed following an intra-peritoneal glucose tolerance test, n-3 downregulated the expression of Srebf1 and the lipogenic genes (Acaca, Fasn). Significant impacts of interventions on intestinal bile acid metabolism, farnesoid X receptor (Fxr) signalling in the intestine and liver, and hepatic expression of fatty acid transporters (Fabp4, Vldlr, Cd36) were also evident. FLAVn-3 may be a novel intervention for NAFLD. Future research should aim to demonstrate its efficacy in the prevention and treatment of human NAFLD.

Chondrocyte responses to neurovascular peptides, cytokines, and a 3D environment: focus on ADAMs

Chondrocyte exposure to inflammatory stimuli in several arthritic conditions, including osteoarthritis, results in the well-characterised induction of extracellular matrix (ECM) degrading proteinases, notably members of a disintegrin and metalloproteinase with thrombospondin domains (ADAMTS) and matrix metalloproteinase (MMP) families. Here we briefly review the less-studied a disintegrin and metalloproteinase (ADAM) family of proteinases in chondrocyte and cartilage biology. Following damage, cartilage is exposed to neurovascular peptides, and in this study we hypothesised that substance P and bradykinin, alongside inflammatory cytokines, may modulate chondrocyte steady state messenger RNA levels for the proteolytic ADAM family members as well as for key cytokines and neuropeptides. We compared chondrocytes cultured in both 2-dimensional (2D) and 3D environments and found that 3D culture generally resulted in repression of expression of the genes under investigation, with the exception of anti-inflammatory interleukin 10 (IL10) which was markedly up-regulated in a 3D environment. Substance P and bradykinin had little effect on ADAM family expression but further investigation revealed that a combination of bradykinin and cytokines led to enhanced expression of ADAM28 and a synergistic up-regulation of IL6, also observed under hypoxic conditions. Overall this data reveals wider chondrocyte responses to neurovascular peptides which may have an impact in an osteoarthritis context.