Dietary supplementation with indole-3-propionic acid (IPA), a tryptophan metabolite that activates AhR, promoted the PMN MDSCs differentiation and CD4+ T-cell inhibition, indicating that IPA-induced AhR activation restored PMN MDSCs function in ESS (191) The AhR-associated mechanisms that drive MDSCs regulation and suppressor functions in Sjögren’s syndrome have been discussed in a recent review (192). Here, AHR is linked to Sjogren syndrome.