efficient-retroviral-transduction-competitive-homing-for

Efficient Retroviral Transduction and Competitive Homing for Investigating GPCR-Mediated T-Cell Localization in Diverse Tissue Microenvironments

Understanding how G-protein coupled receptor (GPCR) expression affects cell positioning within diverse tissue microenvironments is essential for ...

Stanford University School of Medicine

Palo Alto Veterans Institute for Research

Veterans Affairs Palo Alto Health Care System

The integrin αβ selectively regulates lymphocyte trafficking and adhesion in the gut and gut-associated lymphoid tissue (GALT). Here, we describe unexpected involvement of the tyrosine phosphatase Shp1 and the B cell lectin CD22 (Siglec-2) in the regulation of αβ surface expression and gut immunity. Shp1 selectively inhibited β endocytosis, enhancing surface αβ display and lymphocyte homing to GALT. In B cells, CD22 associated in a sialic acid-dependent manner with integrin β on the cell surface to target intracellular Shp1 to β. Shp1 restrained plasma membrane β phosphorylation and inhibited β endocytosis without affecting β integrin. B cells with reduced Shp1 activity, lacking CD22 or expressing CD22 with mutated Shp1-binding or carbohydrate-binding domains displayed parallel reductions in surface αβ and in homing to GALT. Consistent with the specialized role of αβ in intestinal immunity, CD22 deficiency selectively inhibited intestinal antibody and pathogen responses.

A CD22-Shp1 phosphatase axis controls integrin β display and B cell function in mucosal immunity.

Immunoglobulin family and carbohydrate vascular addressins encoded by Madcam1 and St6gal1 control lymphocyte homing into intestinal tissues, regulating immunity and inflammation. The addressins are developmentally programmed to decorate endothelial cells lining gut post-capillary and high endothelial venules (HEV), providing a prototypical example of organ- and segment-specific endothelial specialization. We identify conserved NKX-COUP-TFII composite elements (NCCE) in regulatory regions of Madcam1 and St6gal1 that bind intestinal homeodomain protein NKX2-3 cooperatively with venous nuclear receptor COUP-TFII to activate transcription. The Madcam1 element also integrates repressive signals from arterial/capillary Notch effectors. Pan-endothelial COUP-TFII overexpression induces ectopic addressin expression in NKX2-3 capillaries, while NKX2-3 deficiency abrogates expression by HEV. Phylogenetically conserved NCCE are enriched in genes involved in neuron migration and morphogenesis of the heart, kidney, pancreas and other organs. Our results define an NKX-COUP-TFII morphogenetic code that targets expression of mucosal vascular addressins.

An NKX-COUP-TFII morphogenetic code directs mucosal endothelial addressin expression.

Tissue-selective chemoattractants direct lymphocytes to epithelial surfaces to establish local immune environments, regulate immune responses to food antigens and commensal organisms, and protect from pathogens. Homeostatic chemoattractants for small intestines, colon and skin are known, but chemotropic mechanisms selective for respiratory tract and other non-intestinal mucosal tissues remain poorly understood. Here we leveraged diverse omics datasets to identify GPR25 as a lymphocyte receptor for CXCL17, a chemoattractant cytokine whose expression by epithelial cells of airways, upper gastrointestinal and squamous mucosae unifies the non-intestinal mucosal tissues and distinguishes them from intestinal mucosae. Single-cell transcriptomic analyses show that GPR25 is induced on innate lymphocytes before emigration to the periphery, and is imprinted in secondary lymphoid tissues on activated B and T cells responding to immune challenge. GPR25 characterizes B and T tissue resident memory cells and regulatory T lymphocytes in non-intestinal mucosal tissues and lungs in humans and mediates lymphocyte homing to barrier epithelia of the airways, oral cavity, stomach, and biliary and genitourinary tracts in mouse models. GPR25 is also expressed by T cells in cerebrospinal fluid and CXCL17 by neurons, suggesting a role in central nervous system (CNS) immune regulation. We reveal widespread imprinting of GPR25 on regulatory T cells, suggesting a mechanistic link to population genetics evidence that GPR25 is protective in autoimmunity. Our results define a GPR25-CXCL17 chemoaffinity axis with the potential to integrate immunity and tolerance at non-intestinal mucosae and the CNS.

Article	Year
A CD22-Shp1 phosphatase axis controls integrin β display and B cell function in mucosal immunity. Nature immunology\| PubMed ID: 33589816	2021
An NKX-COUP-TFII morphogenetic code directs mucosal endothelial addressin expression. Nature communications\| PubMed ID: 36460642	2022
A lymphocyte chemoaffinity axis for lung, non-intestinal mucosae and CNS. Nature\| PubMed ID: 39293486	2024

Yuhan Bi

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