Synthetic cannabinoid ajulemic acid exerts potent antifibrotic effects in experimental models of systemic sclerosis

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Garcia Gonzalez, Estrella
Selvi, Enrico
Balistreri, Epifania
Akhmetshina, Alfiya
Palumbo, Katrin
Lorenzini, Sauro
Enea Lazzerini, Pietro
Montilli, Cinzia
Leopoldo Capecchi, Pier
Lucattelli, Monica

Background: Cannabinoids modulate fibrogenesis in scleroderma. Ajulemic acid (AjA) is a non-psychoactive synthetic analogue of tetrahydrocannabinol that can bind the peroxisome proliferator-activated receptor-γ (PPAR-γ). Recent evidence suggests a key role for PPAR-γ in fibrogenesis.

Objective: To determine whether AjA can modulate fibrogenesis in murine models of scleroderma.

Material and methods: Bleomycin-induced experimental fibrosis was used to assess the antifibrotic effects of AjA in vivo. In addition, the efficacy of AjA in pre-established fibrosis was analysed in a modified model of bleomycin-induced dermal fibrosis and in mice overexpressing a constitutively active transforming growth factor β (TGFβ) receptor I. Skin fibrosis was evaluated by quantification of skin thickness and hydroxyproline content. As a marker of fibroblast activation, α-smooth muscle actin was examined. To study the direct effect of AjA in collagen neosynthesis, skin fibroblasts from patients with scleroderma were treated with increasing concentrations of AjA. Protein expression of PPAR-γ, and its endogenous ligand 15d-PGJ2, and TGFβ were assessed before and after AjA treatment.

Results: AjA significantly prevented experimental bleomycin-induced dermal fibrosis and modestly reduced its progression when started 3 weeks into the disease. AjA strongly reduced collagen neosynthesis by scleroderma fibroblasts in vitro, an action which was reversed completely by co-treatment with a selective PPAR-γ antagonist.

Conclusions: AjA prevents progression of fibrosis in vivo and inhibits fibrogenesis in vitro by stimulating PPAR-γ signalling. Since therapeutic doses of AjA are well tolerated in humans, it is suggested that AjA as an interesting molecule targeting fibrosis in patients with scleroderma.

Journal Title
Annals of the Rheumatic Diseases
Annals of the Rheumatic Diseases 71.9 (2012): S. 1545-1551. <>
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