An Innate Disposition for a Healthier Gut: GLP-1R Signaling in Intestinal Epithelial Lymphocytes

Effectiveness and Safety of Semaglutide for Weight Loss in Patients With Inflammatory Bowel Disease and Obesity

BACKGROUND

Semaglutide, a glucagon-like peptide-1 receptor agonist, has shown sustained and clinically significant weight loss in the general population. There are limited data on outcomes of its use in patients with inflammatory bowel disease (IBD).

METHODS

A retrospective cohort study was conducted between June 4, 2021, and December 11, 2023, using TriNetX, a U.S. multi-institutional database in patients with obesity who had IBD compared with patients without IBD. The primary aim was to assess the mean total body weight (TBW) change between 6 and 15 months from initiation of semaglutide compared with baseline between the 2 cohorts. One-to-one (1:1) propensity score matching was performed for demographics, comorbid conditions, smoking status, and mean body mass index. A 2-sample t test was performed to assess mean TBW change from baseline, with a P value <.05 considered to be statistically significant. We also compared the risk of IBD-specific outcomes with and without semaglutide use in patients with IBD.

RESULTS

Out of 47 424 patients with IBD and obesity, 150 (0.3%) patients were prescribed semaglutide (mean age 47.4 ± 12.2 years; mean TBW 237 ± 54.8 pounds; mean body mass index 36.9 ± 6.5 kg/m2; 66% Crohn's disease). There was no difference in mean TBW change after initiation of semaglutide in the IBD and non-IBD cohorts (-16 ± 13.4 pounds vs -18 ± 12.7 pounds; P = .24). There was no difference in mean TBW change between 6 and 12 months (-16 ± 13 pounds vs -15 ± 11.2 pounds; P = .24) and 12 and 15 months (-20 ± 13.2 pounds vs -21 ± 15.3 pounds; P = .49) between the 2 cohorts. There was no difference in the risk of oral or intravenous steroid use and any-cause hospitalization in the semaglutide group compared with the group without semaglutide use in patients with IBD.

CONCLUSION

Semaglutide use is effective in patients with IBD and obesity similar to patients without IBD, with >5% mean weight loss. There was no increased risk of IBD-specific adverse events with semaglutide use.

GLP1 Exerts Paracrine Activity in the Intestinal Lumen of Human Colon

GLP1 produced in the upper part of the gut is released after food intake and acts by activating insulin secretion, but the role of GLP1 in the colon, where it is predominantly produced, remains unknown. Here we characterized the apical versus basolateral secretion of GLP1 and PYY and the paracrine mechanisms of action of these enterohormones in the human colon. We stimulated human colon tissue in different ex vivo models with meat peptone and we used immunofluorescence to study the presence of canonical and non-canonical receptors of GLP1. We found that PYY and GLP1 are secreted mainly at the gut lumen in unstimulated and stimulated conditions. We detected DPP4 activity and found that GLP1R and GCGR are widely expressed in the human colon epithelium. Unlike GLP1R, GCGR is not expressed in the lamina propria, but it is located in the crypts of Lieberkühn. We detected GLP1R expression in human colon cell culture models. We show that the apical secretion of PYY and GLP1 occurs in humans, and we provide evidence that GLP1 has a potential direct paracrine function through the expression of its receptors in the colon epithelium, opening new therapeutic perspectives in the use of enterohormones analogues in metabolic pathologies.

Immune System Effects of Insulin-Like Peptide 5 in a Mouse Model

INTRODUCTION

Insulin-like peptide 5 (INSL5) is a peptide hormone with proposed actions in glucose homeostasis and appetite regulation via its cognate receptor, relaxin family peptide receptor 4 (RXFP4). Here, we look for evidence for their involvement in the immune system using a mouse model.

METHODS

In silico analyses: we queried public databases for evidence of expression of INSL5-RXFP4 in immune system tissues/cells (NCBI's SRA and GeoProfiles) and disorders (EMBO-EBI) and performed phylogenetic footprinting to look for evidence that they are regulated by immune-associated transcription factors (TFs). Experimental analyses: We characterized the expression and correlation of INSL5/RXFP4 and other immune system markers in central and peripheral immune organs from C57/bl6 mice in seven cohorts. We tested whether fluctuations in circulating INSL5 induce an immune response, by injecting mice with 30 μg/kg of INSL5 peptide in the peritoneum, and examining levels of immune markers and metabolic peptides in plasma. Lastly, we quantified the expression of Rxfp4 in T-cells, dendritic cells and cell lines derived from human and mouse and tested the hypothesis that co-incubation of ANA-1 cells in INSL5 and LPS alters cytokine expression.

RESULTS

We find Insl5 expression only in thymus (in addition to colon) where its expression was highly correlated with Il-7, a marker of thymocyte development. This result is consistent with our in silico findings that Insl5 is highly expressed in thymic DP, DN thymocytes and cortical TEC's, and with evidence that it is regulated by thymocyte-associated TF's. We find Rxfp4 expression in all immune organs, and moderately high levels in DCs, particularly splenic DCs, and evidence that it is regulated by immune-associated TF's, such as STAT's and GATA. Systemic effects: We observed significantly elevated concentrations of blood GLP-1, GIP, GCG and PYY following intraperitoneal injection of INSL5, and significantly altered expression of cytokines IL-5, IL-7, M-CSF, IL-15, IL-27 and MIP-2. Immune cell effects: Incubation of ANA-1 cells with INSL5 impeded cell growth and led to a transient elevation of IL-15 and sustained reduction in IL-1β, IL-6 and TNFα.

CONCLUSION

We propose that INSL5-RXFP4 play a novel role in both central and peripheral immune cell signaling.