Margolskee, R. F. | Search bioRxiv

bioRxiv2023

Inflammation induces bitter taste oversensitization via epigenetic changes in Tas2r gene clusters

T2R bitter receptors, encoded by Tas2r genes, are not only critical for bitter taste signal transduction but also important for defense against bacteria and parasites. However, little is known about whether and how Tas2r gene expression are regulated. Here we show that, in an inflammation model mimicking bacterial infection, the expression of many Tas2rs are significantly up-regulated and mice displayed markedly increased neural and behavioral responses to bitter compounds. Using single-cell assays for transposase-accessible chromatin with sequencing (scATAC-seq), we found that the chromatin accessibility of Tas2rs was highly cell type specific and inflammation increased the accessibility of many Tas2rs. scATAC-seq also revealed substantial chromatin remodeling in immune response genes in taste tissue stem cells, suggesting potential long-term effects. Together, our results suggest an epigenetic mechanism connecting inflammation, Tas2r gene regulation, and altered bitter taste, which may explain heightened bitter taste that can occur with infections and cancer treatments.

neuroscience↗

bioRxiv2022

Sweet taste receptor cells may participate in mucosal immune surveillance

The oral microbiome is second only to its intestinal counterpart in diversity and abundance, but its effects on taste cells remains largely unexplored. Using single cell RNASeq, we found that mouse taste receptor cells (STRCs) have a gene expression signature reminiscent of Microfold (M) cells, a central player in immune surveillance in the mucosa associated lymphoid tissue (MALT) such as those in the Peyers patch and tonsils. Administration of Tumor Necrosis Factor Ligand Superfamily Member 11 (TNFSF11, also known as RANKL), a growth factor required for differentiation of M cells dramatically increased M cell proliferation and marker gene expression in the taste papillae and in cultured taste organoids from wild type (WT) mice. Taste papillae and organoids from knockout mice lacking Spib (SpibKO), a RANKL-regulated transcription factor required for M cell development and regeneration on the other hand, failed to respond to RANKL. Taste papillae from SpibKO mice also showed reduced expression of NF-{kappa}B signaling pathway components and proinflammatory cytokines and attracted fewer immune cells. However, lipopolysaccharide-induced expression of cytokines was strongly upregulated in SpibKO mice compared to their WT counterparts. Like M cells, STRCs from WT but not SpibKO mice readily took up fluorescently labeled microbeads, a proxy for microbial transcytosis. The proportion of STRCs and other taste cell subtypes are unaltered in SpibKO mice; however, they displayed increased attraction to sweet and umami taste stimuli. We propose that STRCs are involved in immune surveillance at the taste papillae and tune their taste responses to microbial signaling and infection.

neuroscience↗