Intestinal dysbiosis is thought to confer susceptibility to inflammatory bowel disease (IBD), but it is unknown whether dynamic changes in the microbiome contribute to fluctuations in disease activity. We explored this question using mice with intestine-specific deletion of C1galt1 (also known as T-synthase) (Tsyn mice). These mice develop spontaneous microbiota-dependent colitis with a remitting/relapsing course due to loss of mucin core-1 derived O-glycans. 16S rRNA sequencing and untargeted metabolomics demonstrated age-specific perturbations in the intestinal microbiome and metabolome of Tsyn mice compare with littermate controls at weeks 3 (disease onset), 5 (during remission), and 9 (after relapse). Colitis remission corresponded to increased levels of FoxP3+RORγt+CD4+ T cells in the colonic lamina propria that were positively correlated with operational taxonomic units (OTUs) in the S24-7 family and negatively correlated with OTUs in the Clostridiales order. Relapse was characterized by marked expansion of FoxP3-RORγt+CD4+ T cells expressing IFNγ and IL17A, which were associated with Clostridiales OTUs distinct from those negatively correlated with FoxP3+RORγt+CD4+ T cells. Our findings suggest that colitis remission and relapse in the Tsyn model may reflect alterations in the microbiome due to reduced core-1 O-glycosylation that shift the balance of regulatory and pro-inflammatory T cell subsets. We investigated whether genetic variation in C1galt1 correlated with the microbiome in a cohort of 78 Crohn's disease patients and 101 healthy controls. Polymorphisms near C1galt1 (rs10486157) and its molecular chaperone, Cosmc (rs4825729), were associated with altered composition of the colonic mucosal microbiota, supporting the relevance of core-1 O-glycosylation to host regulation of the microbiome.

Core 1- and 3-derived mucin-type O-glycans are primary components of the mucus layer in the colon. Reduced mucus thickness and impaired O-glycosylation are observed in human ulcerative colitis. However, how both types of O-glycans maintain mucus barrier function in the colon is unclear. We found that C1galt1 expression, which synthesizes core 1 O-glycans, was detected throughout the colon, whereas C3GnT, which controls core 3 O-glycan formation, was most highly expressed in the proximal colon. Consistent with this, mice lacking intestinal core 1-derived O-glycans (IEC C1galt1^-/-) developed spontaneous colitis primarily in the distal colon, whereas mice lacking both intestinal core 1- and 3-derived O-glycans (DKO) developed spontaneous colitis in both the distal and proximal colon. DKO mice showed an early onset and more severe colitis than IEC C1galt1^-/- mice. Antibiotic treatment restored the mucus layer and attenuated colitis in DKO mice. Mucins from DKO mice were more susceptible to proteolysis than wild-type mucins. This study indicates that core 1- and 3-derived O-glycans collectively contribute to the mucus barrier by protecting it from bacterial protease degradation and suggests new therapeutic targets to promote mucus barrier function in colitis patients.

Tumor angiogenesis is critical for cancer progression. In multiple murine models, endothelium-specific epsin deficiency abrogates tumor progression by shifting the balance of VEGFR2 signaling toward uncontrolled tumor angiogenesis, resulting in dysfunctional tumor vasculature. Here, we designed a tumor endothelium-targeting chimeric peptide (UPI) for the purpose of inhibiting endogenous tumor endothelial epsins by competitively binding activated VEGFR2. We determined that the UPI peptide specifically targets tumor endothelial VEGFR2 through an unconventional binding mechanism that is driven by unique residues present only in the epsin ubiquitin-interacting motif (UIM) and the VEGFR2 kinase domain. In murine models of neoangiogenesis, UPI peptide increased VEGF-driven angiogenesis and neovascularization but spared quiescent vascular beds. Further, in tumor-bearing mice, UPI peptide markedly impaired functional tumor angiogenesis, tumor growth, and metastasis, resulting in a notable increase in survival. Coadministration of UPI peptide with cytotoxic chemotherapeutics further sustained tumor inhibition. Equipped with localized tumor endothelium-specific targeting, our UPI peptide provides potential for an effective and alternative cancer therapy.

Colon mucus segregates the intestinal microbiota from host tissues, but how it organizes to function throughout the colon is unclear. In mice, we found that colon mucus consists of two distinct O-glycosylated entities of Muc2: a major form produced by the proximal colon, which encapsulates the fecal material including the microbiota, and a minor form derived from the distal colon, which adheres to the major form. The microbiota directs its own encapsulation by inducing Muc2 production from proximal colon goblet cells. In turn, O-glycans on proximal colon-derived Muc2 modulate the structure and function of the microbiota as well as transcription in the colon mucosa. Our work shows how proximal colon control of mucin production is an important element in the regulation of host-microbiota symbiosis.