Multiple proteins are involved in the protein–DNA complex in the proximal promoter of the human α1(III) collagen gene (COL3A1)

Interleukin-17A promotes functional activation of systemic sclerosis patient-derived dermal vascular smooth muscle cells by extracellular-regulated protein kinases signalling pathway

INTRODUCTION

Dermal vascular smooth muscle cells (DVSMCs) are important for vascular wall fibrosis in microangiopathy of systemic sclerosis (SSc). T helper 17 cell-associated cytokines, particularly interleukin-17A (IL-17A), have been demonstrated to play a role in the pathogenesis of SSc. However, the effect of IL-17A on the DVSMCs in microangiopathy of SSc has not been established. In the present study, we investigated the effect of IL-17A on the SSc patient-derived DVSMCs.

METHODS

DVSMCs from patients with SSc and healthy subjects were incubated using IL-17A or serum derived from patients with SSc. Subsequently, the proliferation, collagen synthesis and secretion, and migration of DVSMCs were analysed using a cell counting kit-8 (CCK-8), dual-luciferase reporter assay, real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blot, enzyme-linked immunosorbent assay (ELISA) and transwell assay. The protein phosphorylation of signalling pathways in the process of IL-17A-mediated DVSMC activation was investigated and validated by specific signalling pathway inhibitor.

RESULTS

IL-17A and serum from patients with SSc could promote the proliferation, collagen synthesis and secretion, and migration of DVSMCs. IL-17A neutralising antibody could inhibit the IL-17A-induced activation of DVSMCs. Additionally, IL-17A induced the activation of extracellular-regulated protein kinases 1/2 (ERK1/2) in DVSMCs, and ERK1/2 inhibitor could block the IL-17A-elicited activation of DVSMCs.

CONCLUSIONS

Our results suggested that IL-17A derived from patients with SSc might induce the proliferation, collagen synthesis and secretion, and migration of DVSMCs via ERK1/2 signalling pathway, raising the likelihood that IL-17A and ERK1/2 might be promising therapeutic targets for the treatment of SSc-related vasculopathy.

PPARdelta promotes wound healing by up-regulating TGF-beta1-dependent or -independent expression of extracellular matrix proteins

Although the peroxisome proliferator-activated receptor (PPAR) δ has been implicated in the wound healing process, its exact role and mechanism of action have not been fully elucidated. Our previous findings showed that PPARδ induces the expression of the transforming growth factor (TGF)-β1, which has been implicated in the deposit of extracellular matrix proteins. Here, we demonstrate that administration of GW501516, a specific PPARδ ligand, significantly promoted wound closure in the experimental mouse and had a profound effect on the expression of collagen types I and III, alpha-smooth muscle actin, pSmad3 and TGF-β1, which play a pivotal role in wound healing processes. Activation of PPARδ increased migration of human epidermal keratinocytes and dermal fibroblasts in in vitro scrape-wounding assays. Addition of a specific ALK5 receptor inhibitor SB431542 significantly suppressed GW501516-induced migration of human keratinocytes and fibroblasts. In these cells, activated PPARδ also induced the expression of collagen types I and III and fibronectin in a TGF-β1-dependent or -independent manner. The effect of PPARδ on the expression of type III collagen was dually regulated by the direct binding of PPARδ and Smad3 to a direct repeat-1 site and a Smad-binding element, respectively, of the type III gene promoter. Taken together, these results demonstrated that PPARδ plays an important role in skin wound healing in vivo and that it functions by accelerating extracellular matrix-mediated cellular interactions in a process mediated by the TGF-β1/Smad3 signaling-dependent or - independent pathway.

Peroxisome proliferator-activated receptor {delta} regulates extracellular matrix and apoptosis of vascular smooth muscle cells through the activation of transforming growth factor-{beta}1/Smad3

Homeostasis of the extracellular matrix and apoptosis of vascular smooth muscle cells (VSMCs) are key components in the regulation of the stability of atherosclerotic plaques. Here, we demonstrate that peroxisome proliferator-activated receptor (PPAR)delta regulates extracellular matrix synthesis and degradation through transforming growth factor-beta1 and its effector, Smad3. Activation of PPARdelta strongly amplified the expression of types I and III collagen, fibronectin, elastin, and TIMP-3 (tissue inhibitor of metalloproteinases 3), but not of TIMP-1, matrix metalloproteinase-2 or -9. The effect of PPARdelta on the expression of type III collagen was dually regulated by the direct binding of PPARdelta and Smad3 to a direct repeat-1 site and a Smad-binding element, respectively, in the type III collagen gene promoter. The activation of PPARdelta attenuated apoptotic cell death in VSMCs induced by oxidized low-density lipoprotein, and similar antiapoptotic effects were observed on treatment of cells with exogenous type I and/or III collagen. Administration of a PPARdelta ligand GW501516 to mice also suppressed elastase-induced cell death of aortic VSMCs. These results suggest that PPARdelta-induced upregulation of extracellular matrix proteins exerts an antiapoptotic effect, thereby maintaining the stability of atherosclerotic plaques. Specific ligands of PPARdelta may aid in the therapeutic intervention of atherosclerosis by improving plaque stability and patient prognosis.

Mesenchymal stem cells attenuate cardiac fibroblast proliferation and collagen synthesis through paracrine actions

Mesenchymal stem cells (MSC) transplantation has been shown to decrease fibrosis in the heart; however, whether MSC directly influence the function of cardiac fibroblasts (CFB) remains unknown. MSC-conditioned medium significantly attenuated proliferation of CFB compared with CFB-conditioned medium. MSC-conditioned medium upregulated antiproliferation-related genes such as elastin, myocardin and DNA-damage inducible transcript 3, whereas CFB-conditioned medium upregulated proliferation-related genes such as alpha-2-macroglobulin and v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog. MSC-conditioned medium significantly downregulated type I and III collagen expression, and significantly suppressed type III collagen promoter activity. MSC may exert paracrine anti-fibrotic effects at least in part through regulation of CFB proliferation and collagen synthesis.