Biology subjects

Hashimoto-Hill, S.

Publications and source records attributed to Hashimoto-Hill, S..

3 recordsLinked to original sources

bioRxiv2025

Epithelial-intrinsic nitric oxide synthase 2 sustains host-microbiota dynamics that promote colitis

The microbiota influence disease pathogenesis and treatment, however we have limited ability to assess patient status in relation to the microbiota. Here we find that the nitric oxide generating enzyme, nitric oxide synthase 2 (Nos2), is transcriptionally primed in intestinal epithelial cells (IECs), as opposed to immune cells, in inflammatory bowel disease (IBD) patients. Generation of IEC-specific Nos2 knockout mice revealed that epithelial Nos2 activity promoted susceptibility to intestinal disease and sustained a colitogenic microbiota. Epithelial Nos2 increased levels of nitric oxide-derived nitrates and nitrate-metabolizing bacteria in the intestine. Unexpectedly, extra-intestinal nitrates also reflected IEC-intrinsic Nos2 expression, and systemic nitrate concentrations in patients paralleled intestinal Nos2 activation. In fact, temporally inhibiting epithelial Nos2 was sufficient to alter intestinal nitrate homeostasis and inflammation in mice, as well as restrict nitrate production by human intestinal organoids. These data reveal that epithelial nitric oxide metabolism directs host-microbiota dynamics that can alter disease and that monitoring and targeting this axis may benefit patients with IBD.

immunology↗

bioRxiv2023

Microbiota epigenetically direct tuft cell differentiation to control type 2 immunity

Allergy and anti-helminth immunity are driven by type 2 responses in mucosal tissues. Tuft cells are key regulators of type 2 immunity, however the factors that control these cells remain poorly understood. Here we find that butyrate-producing commensal bacteria decrease tuft cells in the intestine. Butyrate suppression of tuft cells required the epigenetic modifying enzyme histone deacetylase 3 (HDAC3), suggesting that HDAC3 may promote tuft cell-dependent immunity. Consistent with this, epithelial-intrinsic HDAC3 actively regulated tuft cell expansion in vivo and was required to induce type 2 immune responses during helminth infection. Interestingly, butyrate epigenetically restricted stem cell differentiation into tuft cells, and inhibition of HDAC3 in adult mice and human intestinal organoids was sufficient to block tuft cell expansion. Collectively, these data reveal an epigenetic pathway in stem cells that directs tuft cell differentiation, and highlight a new level of regulation through which commensal bacteria calibrate intestinal immunity.

immunology↗

bioRxiv2021

Commensal bacterial-derived retinoic acid primes host defense to intestinal infection

Interactions between the microbiota and mammalian host are essential for effective defense against pathogenic infection; however, the microbial-derived cues that mediate this beneficial relationship remain unclear. Here, we find that the intestinal epithelial cell (IEC)-associated commensal bacteria, Segmented Filamentous Bacteria (SFB), promotes early protection against the bacterial pathogen, Citrobacter rodentium, independently of CD4+ T cells. Global analyses demonstrated that SFB induced histone modifications in IECs at sites enriched for the retinoic acid receptor (RAR) motif. Interestingly, SFB-colonized mice exhibited greater expression of RAR targets during infection relative to germ-free mice, suggesting SFB may enhance defense through retinoic acid (RA) signaling. Consistent with this, supplementing germ-free mice with RA decreased pathogen levels. Further, mice with impaired RA-responsiveness in IECs displayed increased susceptibility to C. rodentium infection. RA was elevated in the intestine of mice colonized with SFB, indicating that the presence of commensal bacteria can modulate intestinal RA levels. However, this regulation by SFB was not dependent on mammalian RA production. Sequence analyses suggested that RA-generating enzymes are expressed by a subset of commensal bacteria. Remarkably, RA was produced by intestinal bacteria including SFB, and inhibiting RA signaling blocked SFB-induced protection against C. rodentium infection. These data collectively reveal RA as an unexpected microbiota-derived metabolite that primes innate intestinal defense and suggests that pre- and probiotic approaches to elevate RA could prevent or combat pathogenic infection.

microbiology↗