INVESTIGATION OF THE EFFECT OF OUTER MEMBRANE VESICLES (OMVs) FROM AKKERMANSIA MUCINIPHILA ON M2 MACROPHAGE DIFFERENTIATION AND FUNCTION VIA TLR2/TLR9 AND THEIR THERAPEUTIC POTENTIAL IN TYPE 2 DIABETES.

• Grant number: 24/06798-9
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: March 01, 2025
• End date: February 28, 2027
• Field of knowledge: Biological Sciences - Immunology - Applied Immunology
• Principal Investigator: Daniela Carlos Sartori
• Grantee: Raquel Pires Nakama
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated research grant: 18/14815-0 - Evaluation of the intestinal microbioma profile and of the therapeutic potential of intervention strategies in the immunopathogeny of type 1 and 2 Diabetes, AP.JP2

Abstract

The etiology of Type 2 Diabetes Mellitus (T2DM) is multifactorial, interconnected with genetic, environmental, dietary, and metabolic factors. The gut microbiota plays an important role in intestinal homeostasis through the expression of molecular patterns associated with microorganisms (MAMPs), production of metabolites, and secretion of outer membrane vesicles (OMVs). Through interactions with innate immune leukocytes and intestinal epithelial cells via pattern recognition receptors (PRRs), the gut microbiota contributes to the regulation of the intestinal barrier and the control of meta-inflammation in metabolic diseases. Our research group has found an inverse correlation between meta-inflammation and the abundance of the probiotic bacterium Akkermansia muciniphila during the progression of T2DM. It has been shown that A. muciniphila induces an increase in goblet cells in the intestine, thereby restoring the mucus layer that is damaged in a model of obesity induced by a high-fat diet (HFD). Additionally, A. muciniphila OMVs (AmOMVs) maintain the integrity of the epithelial barrier by increasing the expression of tight junction proteins, such as occludin and claudin-4, while reducing the expression of toll-like receptors (TLRs), such as TLR2 and TLR4. Moreover, AmOMVs promote the reduction of pro-inflammatory cytokines TNF-¿ and IL-6 and enhance IL-4. Bacterial OMVs are capable of carrying proteins, enzymes, peptidoglycan (PGN), RNA, non-methylated DNA (CpG-DNA), or metabolites, which can be recognized and activate TLR receptors. Thus, our hypothesis is that the administration of AmOMVs in obese mice can control meta-inflammation by inducing M2 macrophages and prevent/slow the progression of T2DM. Mechanistically, we aim to evaluate whether in vitro stimulation of bone marrow-derived macrophages with AmOMVs promotes, either directly or indirectly, the differentiation of type 2 macrophages (M2) in vitro through a mechanism mediated by TLR2 or TLR9 via PGN or CpG-DNA, respectively. In parallel, we will test whether the administration of AmOMVs promotes a resolutive/anti-inflammatory microenvironment of M2 macrophages via TLR2 or TLR9 in visceral adipose tissue (VAT) with the capacity to attenuate the inflammatory and metabolic alterations associated with HFD-induced T2DM. Finally, we will characterize AmOMVs (size, structure, and composition) using electron microscopy and metabolomic analysis. The results obtained from this project are innovative and translational, as they may demonstrate the use of AmOMVs as a potential adjunctive therapeutic approach in the prevention or treatment of T2DM in humans.