Activation of aryl hydrocarbon receptor ameliorates degranulation of LL-37 induced mast cells in rosacea through enhancing autophagy

Background: Activation of the Aryl Hydrocarbon Receptor (AhR) ameliorates LL-37-induced rosacea-like dermatitis in mice, whereas mast cells and cytokine overexpression are prominent features in rosacea skin.

Objective: To evaluate the potential mechanisms of AhR activation on Autophagy and degranulation of mast cells in rosacea.

Methods: LL-37 treated mast cells were used to mimic rosacea. An AhR agonist (tapinarof) was applied to LL-37 induced mast cells. Furthermore, an Autophagy agonist (RAPA) and an inhibitor (CQ) was added to investigate the mechanisms of Autophagy. Western blot and RT-qPCR assessed cell degranulation (Cma1, Tpsab1) and cytokines (MMP9, TNF-α, and IL-6). Changes in cell morphology were observed under a microscope. Autophagy markers (LC3 and p62) were examined using Western blot and cellular immunofluorescence.

Results: LL-37 upregulated the expressions of Cma1, Tpsab1, MMP9, TNF-α, and IL-6, which were then reduced by tapinarof treatment for 24 h. LC3B-I was converted to LC3B-II and p62 was reduced gradually with increasing concentration of tapinarof, indicating that Autophagy was enhanced. RAPA enhanced the expression of LC3B-II on LL-37-induced mast cells, similar to tapinarof, while CQ partially inhibited the ability of tapinarof to induce Autophagy in mast cells. Moreover, CQ reversed tapinarof's suppression of Cma1, Tpsab1, MMP9, TNF-α and IL-6 on LL-37 treated mast cells.

Conclusion: The present study showed that activation of AhR ameliorated degranulation of LL-37-induced mast cells in rosacea through enhancing Autophagy, offering a new option for rosacea treatment.

AhR; Autophagy; Degranulation; LL-37; Mast cells; Rosacea.