Targeting cannabinoid receptor 2 (CB2) limits collagen production—An in vitro study in a primary culture of human fibroblasts

Abstract

Abstract Previous studies showed that cannabinoid 2 (CB2) receptor is involved in skin inflammation, fibrogenesis and re‐epithelialization in mice, indicating that this receptor may be implicated in wound healing. Thus, topical use of cannabinoids may have a role in local fibrotic and wound healing diseases such as scars or keloids. We investigate the effect of the CB2 selective receptor agonist (6aR,10aR)‐3‐(1,1‐Dimethylbutyl)‐6a,7,10,10a‐tetrahydro‐6,6,9‐trimethyl‐6H‐dibenzo[b,d]pyran (JWH133) and the CB2 selective receptor antagonist (6‐Iodo‐2‐methyl‐1‐[2‐(4‐morpholinyl)ethyl]‐1H‐indol‐3‐yl)(4‐methoxyphenyl)‐methanone (AM630), on primary cultures of human fibroblasts. Primary cultures of adult human fibroblasts were obtained from abdominal human skin samples. Fibroblasts pretreated with JWH133 and/or AM630 were stimulated with TGF‐ β (10 ng/ml). Fibroblast activation into myofibroblasts was quantified by the expression of alpha‐smooth muscle actin ( α ‐SMA) using Immunocytochemistry and Western Blot assays. Collagen content was quantified with the Sirius red staining assay. Upon human fibroblasts stimulation with TGF‐ β, a significant increase on α ‐SMA and CB2 receptor expression was observed. In these cells, JWH133 decreased α ‐SMA expression and collagen content. However, this effect was not observed in resting human fibroblasts. AM630 decreased α ‐SMA expression and collagen content in both resting and activated fibroblasts. This effect was time‐ and concentration‐dependent with an IC 50 value of 11 μM. The CB2 receptor appears to be involved in fibroblast repair during skin wound healing in humans, as TGF‐ β increases CB2 receptor expression and JWH133 produces an anti‐fibrotic effect in human fibroblasts. AM630 also showed an anti‐fibrotic effect hypothesizing that other cannabinoid receptors, such as TRPV, may be involved in this response.

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