Adiponectin Is Involved in Connective Tissue Growth Factor-Induced Proliferation, Migration and Overproduction of the Extracellular Matrix in Keloid Fibroblasts

Abstract

Adiponectin, an adipocyte-derived hormone, exerts pleiotropic biological effects on metabolism, inflammation, vascular homeostasis, apoptosis and immunity. Recently, adiponectin has been suggested to attenuate the progression of human dermal fibrosis. Connective tissue growth factor (CTGF) is induced in keloids and is thought to be participated in the formation of keloid fibrosis. However, the roles played by adiponectin in keloids remain unclear. In this study, we explored the effects of adiponectin on CTGF-induced cell proliferation, migration and the deposition of extracellular matrix (ECM) and their associated intracellular signalling pathways in keloid fibroblasts (KFs). We also explored possible mechanisms of keloid pathogenesis. Primary fibroblast cultures were established from foreskin biopsies and skin biopsies from patients with keloids. The expression of adiponectin and adiponectin receptors (adipoRs) was evaluated by reverse transcription-PCR (RT-PCR), quantitative real-time RT-PCR, immunofluorescence staining, and immunohistochemical analysis. Next, KFs and normal dermal fibroblasts (NFs) were treated with CTGF in the presence or absence of adiponectin. A cell counting kit-8 (CCK-8) and the Transwell assay were used to examine cell proliferation and migration. The level of the collagen I, fibronectin (FN) and α-smooth muscle actin (α-SMA) mRNAs and proteins were determined by quantitative real-time RT-PCR and western blotting. The effects of RNA interference (RNAi) targeting the adipoR genes were detected. Phosphorylation of adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 kinase-protein kinase (PI3K-Akt) were examined by western blotting to further investigate the signalling pathways. Furthermore, inhibitors of signal transduction pathways were investigated. The expression levels of adiponectin and adipoRs were significantly decreased in keloids compared with those in normal skin tissue. Adiponectin suppressed the CTGF-induced KFs, but not NFs, proliferation, migration and ECM production. Moreover, adiponectin inhibited the phosphorylation of AMPK, p38 and extracellular-regulated kinase (ERK), but not that of Jun N-terminal kinase (JNK) or Akt, in CTGF-treated KFs. The activity of adiponectin-mediated signalling pathways was attenuated by small interfering RNAs (siRNAs) targeting adipoR1 (but not siRNAs targeting adipoR2, T-cadherin or calreticulin), AMPK (Compound C), p38 (SB203580) inhibitors, and mitogen-activated protein kinase kinase (MEK) inhibitor (PD98059). Based on our results, adiponectin suppresses CTGF-induced KFs proliferation, migration and ECM overproduction. One of the underlying mechanisms is the activation of the adipoR1, AMPK, p38, and ERK signalling pathways. Therefore, adiponectin may play an important role in the progression of keloids, suggesting a potential novel target for keloid treatment.

Nintedanib inhibits keloid fibroblast functions by blocking the phosphorylation of multiple kinases and enhancing receptor internalization

“…As these pathological aspects of keloids are mediated by growth factors, including TGF-β, PDGF, VEGF, and bFGF, drug treatments are likely to inhibit the functions of these factors. For example, CTGF, a growth factor downstream of TGF-β [ 35 , 36 ], was found to be downregulated at both the gene and protein levels, which may account for the inhibition of cell proliferation and matrix production.…”

In VitroandEx VivoModels for Functional Testing of Therapeutic Anti-scarring Drug Targets in Keloids

“…39,40 For instance, connective tissue growth factor (CTGF), was demonstrated to be involved in intracellular signaling pathways in KFs. 41 It was found that CTGF could stimulate proliferation, migration, and accumulation of ECM produced by KFs. Further, it was also revealed that adiponectin suppresses' CTGF-induced KFs proliferation, migration, and ECM production with resultant attenuation of CTGF-induced phosphorylation of adipoR1 (adiponectin receptor 1), adenosine monophosphate-activated protein kinase (AMPK) mitogen activated protein kinase (p38), and extracellular-regulated kinase (ERK) signaling pathways.…”

Prevention of the Formation of Unaesthetic Scars Following the Surgical Cutaneous Wounds Healing of the Jaw and Facial Region Based on Transplantation of Xenogenic Fibroblasts

“…The progression of wound healing, including skin, is called the wound process and includes three stages: inflammation, proliferation with the formation of granulation tissue, and remodeling or fibrosis. (15) Wound healing without scarring is possible only in fetuses in the first 6-7 months of pregnancy due to the absence of the inflammatory phase of the wound process. (16) It is inflammation that plays a key role in the morphology of the future scar.…”