N-Acylethanolamine acid amidase (NAAA) inhibition rescues intestinal fibrosis through IL-23 pathway

Einleitung Intestinal fibrosis is a frequent complication in inflammatory bowel disease characterized by stricture formation and bowel obstruction. The pharmacological treatment is unsatisfactory, therefore, the elucidation of fibrosis mechanisms as well as the discovery of novel pharmacological treatments is a top priority [1] [2]. N-Acylethanolamine acid amidase (NAAA) is a lysosomal enzyme responsible of the breakdown of N-acylethanolamides (NAEs) (i.e., palmitoylethanolamide PEA, anandamide AEA and oleoylethanolamide OEA). NAAA inhibition is reported to be effective in several inflammatory disorders including those affecting the intestine [3] and some NAEs counteract key mediators involved in organ fibrosis [4]. However, the role of NAAA and NAEs signalling in gut fibrosis is undiscovered to date.

Material und Methodik Intestinal fibrosis was induced in mice by TNBS and evaluated by disease activity index (DAI), colonoscopy, qRT-PCR, histological analyses (eosin & hematoxilin and Masson's trichrome stain) and confocal microscopy. Immune cell populations (Th1, Th2, Th17, Treg) were analysed from mesenteric lymph nodes by flow cytometry analysis. IL-23 signalling was evaluated on bone marrow-derived macrophages (BMDM) exposed to lipopolysaccharide (LPS); cytokines levels were evaluated by qRT-PCR and ELISA. Human intestinal specimens were surgically obtained from stenotic Crohn’s diseases (CD) patients. NAAA expression was evaluated by western blot and NAEs levels in murine and human specimens were analysed by Liquid Chromatography−Atmospheric Pressure Chemical Ionization−Mass Spectrometry (LC-APCI-MS).

Ergebnisse NAAA pharmacological inhibition induced by AM9053 determined a rescue of gut fibrosis in terms of reduction of DAI, murine endoscopic index of colitis severity, collagen deposition without affecting the expression of α-SMA. AM9053 almost neutralized the colonic expression of IL-23 and affected the main genes involved in epithelial to mesenchymal transition. NAAA inhibition determined an increase of PEA levels in fibrotic mice. AM9053 strongly down-regulated Th1 and Th17 cell population induced by TNBS. AM9053 significantly reduced in primary BMDM (i.e., main producers of IL-23) the production of IL-23 as well as the cytokines/proteins correlated to its release (i.e., TGF-β, IL-1β, IL-6, TNF-α, RORγT, IL-17). In fibrotic CD patients, NAAA protein expression was upregulated accompanied with a significant reduction of PEA and OEA levels.

Zusammenfassung Our results provide novel insights into the functional role of NAAA and NAEs signalling in intestinal fibrosis. These results point out on the possible therapeutic efficacy of targeting NAAA and/or NAEs in fibrotic patients.

Publication History

Article published online:
09 March 2023

• Literatur

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