The role of GPCRs and homing molecules in the control and regionalization of mucosal immunity.

Introduction

Mucosal immunity is essential to preserve homeostasis and for pathogen control within the gut and the airways. The emerging dogma of immune regionalization has opened new questions about which elements drive cell adaptation to different niches, and how this can be targeted to cure diseases.

Functional Diversity of Mucosal Tissues

The intestine and the airways are functionally diverse along their length, and disorders can differentially impact different mucosal tissue regions. Mucosa-associated lymphoid tissues (MALTs) are located along the intestine and the airways to drain selective tissue segments and support protective immunity.

Immune Regionalization and MALTs

Whether MALTs located in different tissue areas show immune regionalization remains poorly understood. Also, little is known about which molecules control such immune diversity.

Role of GPCRs

G protein-coupled receptors (GPCRs) are surface proteins important for cell migration and compartmentalization in lymphoid tissues, but their role in immune regionalization is not clear.

Proposed Methodology

We propose to apply a combination of imaging, flow cytometry, spatial gene editing, and sequencing techniques to study the role of GPCRs in immune regionalization of MALTs, at steady state and in disease.

Intestinal Analysis

In the intestine, we will:

1. Phenotypically and functionally profile immune cells.
2. Analyze GPCRs expression within Peyer's patches (PPs) from different gut regions, in physiology or in the context of inflammation and obesity.

Airway Analysis

Similarly, we will analyze immune regionalization of:

• Bronchus-associated lymphoid tissues.
• Nose-associated lymphoid tissues within the airways, at steady state or upon infections.

Candidate GPCR Characterization

Finally, we will characterize the role of a candidate GPCR, GPR35, in the induction of intestinal and respiratory immunity. Our preliminary data show that GPR35 shapes cell recruitment to inflamed airways and influences cell positioning within PPs.

Conclusion

By applying the above-mentioned approaches and dedicated mouse models, we will study how GPR35 regulates mucosal immunity and if it represents an attractive clinical target.