2. Academic Validation
  3. Inflamed Ulcerative Colitis Regions Associated With MRGPRX2-Mediated Mast Cell Degranulation and Cell Activation Modules, Defining a New Therapeutic Target

Inflamed Ulcerative Colitis Regions Associated With MRGPRX2-Mediated Mast Cell Degranulation and Cell Activation Modules, Defining a New Therapeutic Target

  • Gastroenterology. 2021 Apr;160(5):1709-1724. doi: 10.1053/j.gastro.2020.12.076.
Ernie Chen 1,  Ling-Shiang Chuang 1,  Mamta Giri 1,  Nicole Villaverde 1,  Nai-Yun Hsu 1,  Ksenija Sabic 1,  Sari Joshowitz 1,  Kyle Gettler 1,  Shikha Nayar 1,  Zhi Chai 2,  Isaac L Alter 2,  Colleen C Chasteau 1,  Ujunwa M Korie 1,  Siarhei Dzedzik 3,  Tin Htwe Thin 3,  Aayushee Jain 1,  Arden Moscati 1,  Gerardus Bongers 4,  Richard H Duerr 5,  Mark S Silverberg 6,  Steven R Brant 7,  John D Rioux 8,  Inga Peter 1,  L Philip Schumm 9,  Talin Haritunians 10,  Dermot P McGovern 10,  Yuval Itan 1,  Judy H Cho 11
Affiliations

Affiliations

  • 1 The Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai, New York; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York.
  • 2 The Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai, New York.
  • 3 Department of Pathology, Icahn School of Medicine at Mount Sinai, New York.
  • 4 Precision Immunology Institute at the Icahn School of Medicine at Mount Sinai, New York.
  • 5 Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania.
  • 6 Zane Cohen Centre for Digestive Diseases, Division of Gastroenterology, Mount Sinai Hospital, University of Toronto, Ontario, Canada, Toronto, Ontario, Canada.
  • 7 Crohns and Colitis Center of New Jersey, Division of Gastroenterology and Hepatology, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey.
  • 8 Research Centre, Montreal Heart Institute, Montréal, Quebec, Canada; Faculty of Medicine, Université de Montréal, Montréal, Quebec, Canada.
  • 9 Department of Health Sciences, University of Chicago, Chicago, Illinois.
  • 10 F. Widjaja Foundation Inflammatory Bowel and Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, California.
  • 11 The Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai, New York; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York. Electronic address: Judy.cho@mssm.edu.
PMID: 33421512 DOI: 10.1053/j.gastro.2020.12.076
Abstract

Background & aims: Recent literature has implicated a key role for mast cells in murine models of colonic inflammation, but their role in human ulcerative colitis (UC) is not well established. A major advance has been the identification of mrgprb2 (human orthologue, MRGPX2) as mediating IgE-independent mast cell activation. We sought to define mechanisms of mast cell activation and MRGPRX2 in human UC.

Methods: Colon tissues were collected from patients with UC for bulk RNA Sequencing and lamina propria cells were isolated for MRGPRX2 activation studies and single-cell RNA Sequencing. Genetic association of all protein-altering G-protein coupled receptor single-nucleotide polymorphism was performed in an Ashkenazi Jewish UC case-control cohort. Variants of MRGPRX2 were transfected into Chinese hamster ovary (CHO) and human mast cell (HMC) 1.1 cells to detect genotype-dependent effects on β-arrestin recruitment, IP-1 accumulation, and phosphorylated extracellular signal-regulated kinase.

Results: Mast cell-specific mediators and Adrenomedullin (proteolytic precursor of PAMP-12, an MRGPRX2 agonist) are up-regulated in inflamed compared to uninflamed UC. MRGPRX2 stimulation induces Carboxypeptidase secretion from inflamed UC. Of all protein-altering GPCR alleles, a unique variant of MRGPRX2, Asn62Ser, was most associated with and was bioinformatically predicted to alter Arrestin recruitment. We validated that the UC protective serine allele enhances β-arrestin recruitment, decreases IP-1, and increases phosphorylated extracellular signal-regulated kinase with MRGPRX2 agonists. Single-cell RNA Sequencing defines that Adrenomedullin is expressed by activated fibroblasts and epithelial cells and that interferon gamma is a key upstream regulator of mast cell gene expression.

Conclusion: Inflamed UC regions are distinguished by MRGPRX2-mediated activation of mast cells, with decreased activation observed with a UC-protective genetic variant. These results define cell modules of UC activation and a new therapeutic target.

Keywords

G-Protein Coupled Receptors; Mast Cells; Single Cell Sequencing; Ulcerative Colitis.

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