Subspecialty	Gastroenterology
Languages	English
Gender	Male
E-mail	lloyd.mayer@mssm.edu
Education and Training	MD, Mount Sinai School of Medicine
	Residency, Internal Medicine, New York University Medical Center
	Fellowship, Gastroenterology, Mount Sinai Hospital
Awards	2009 Best Doctors New York Magazine

Dr. Mayer is Professor and Director of the Immunology Institute, Professor of Medicine and Chief of the Divisions of Clinical Immunology and Gastroenterology. He is co-program director of the Allergy/Immunology training program and teaches in the graduate and medical school. His research interests lie in mucosal immunity, most specifically in antigen processing and presentation, mucosal regulatory T cell activation and tolerance induction, cytokine regulation and B cell maturation with a translational focus on primary immunodeficiency disorders. The studies relating to mucosal immunity have provided new insights into the pathogenesis of inflammatory bowel disease. He is currently the principle investigator of a PPG on innate and adaptive mucosal immunity/inflammatory bowel disease, an RO1 (HIV/macrophage interactions), the PI on one project in a program project grant on food hypersensitivity, a co-PI on a U19 grant focused on peanut and egg allergy (PI of the mechanistic studies), a co-investigator on a bioterrorism U19 grant (human studies) and a co-investigator on a project and the PI of a core (flow cytometry) in a program project grant on primary immunodeficiency.

Mailing Address:
Mount Sinai Medical Center
1425 Madison Avenue
Box 1069
New York, NY 10029

Education and Training	MD, Mount Sinai School of Medicine
	Residency, Internal Medicine, New York University Medical Center
	Fellowship, Gastroenterology, Mount Sinai Hospital
Board Certification	Gastroenterology

Subspecialty	Gastroenterology
Languages	English
Board Certification	Gastroenterology

Specific Clinical/Research Interests: Regulation of mucosal immune responses; antigen presentation by intestinal epithelial cells
Current Students: Keren Rabinowitz
Postdoctoral Fellows: Stephanie Dahan, Dmitry Yarilin, Paul Arnaboldi, David Dunkin, Surabh Mehandru, Zara Hovhannisyan
Research Personnel: Research Assistant:, Jianyu Xu, Paul Smereka

Summary of Research Studies:
Our laboratory studies the regulation of mucosal immune responses in both human and murine systems. Specifically we focus on the role that intestinal epithelial cells play in this process. Intestinal epithelial cells express non-classical class I molecules that are involved in the activation of unique populations of regulatory T cells. They also express a tumor associated antigen, carcinoembryonic antigen, that, along with CD1d, activates a population of CD8+ Tregs called TrE cells. Current studies focus on the characterization of different Treg populations in the intestine as well as different CEA subfamily members and their ability to interact with distinct class Ib molecules. These studies have extended into the role of such cells in fetal/maternal interactions where activation of distinct Treg populations may occur restricted by other CEA subfamily members.. Other studies in muriine systems look at the role of epithelial cell antigen presentation in vivo, by the induction of oral tolerance. Antigens are introduced in isolated intestinal loops and tolerance induction is assessed. Data show that tolerance can be induced in loops that contain organized lymphoid tissues (Peyer's patches) as well as those where there are no PPs (epithelial cells only). Current studies focus on defining differing mechanisms of tolerance induction in the two loops. Finally, we are interested in translating these findings into human disease. We have developed models of abnormal antigen presentation in inflammatory bowel disease (Crohn's disease and ulcerative colitis). Epithelial cells derived from surgical specimens from these patients fail to activate TrE cells but rather activate inflammatory CD4+ T cells. Defects in class Ib and CEA expression appear to be responsible for this finding. Defining mechanisms involved in the failure to express these regulatory surface molecules is a current focus. This has been translated into in vivo assessments. We have also identified defects in oral tolerance in these patients. The mechanisms involved in the generation of oral tolerance in normal controls as well as the mechanisms involved in the defect in oral tolerance in IBD patients are also being studied.

Berin MC, Mayer L. Immunophysiology of experimental food allergy. Mucosal Immunol 2009 Jan; 2(1): 24-32.

Roth-Walter F, Berin MC, Arnaboldi P, Escalante CR, Dahan S, Rauch J, Jensen-Jarolim E, Mayer L. Pasteurization of milk proteins promotes allergic sensitization by enhancing uptake through Peyer's patches . Allergy 2008 Jul; 63(7): 882-890.

Shang L, Fukata M, Thirunarayanan N, Martin AP, Arnaboldi P, Maussang D, Berin C, Unkeless JC, Mayer L, Abreu MT, Lira SA. Toll-like receptor signaling in small intestinal epithelium promotes B-cell recruitment and IgA production in lamina propria . Gastroenterology 2008 Aug; 135(2): 529-538.

Shao L, Jacobs AR, Johnson VV, Mayer L. Activation of CD8+ regulatory T cells by human placental trophoblasts. J Immunol 2005 Jun 15; 174(12): 7539-7547.

Li H, Chehade M, Liu W, Xiong H, Mayer L, Berin MC. Allergen-IgE complexes trigger CD23-dependent CCL20 release from human intestinal epithelial cells . Gastroenterology 2007 Dec; 133(6): 1905-1915.

Dahan S, Roda G, Pinn D, Roth-Walter F, Kamalu O, Martin AP, Mayer L. Epithelial: lamina propria lymphocyte interactions promote epithelial cell differentiation . Gastroenterology 2008 Jan; 134(1): 192-203.

Knight AK, Blazquez AB, Zhang S, Mayer L, Sampson HA, Berin MC. CD4 T cells activated in the mesenteric lymph node mediate gastrointestinal food allergy in mice . Am J Physiol Gastrointest Liver Physiol 2007 Dec; 293(6): G1234-G1243.

Kraus TA, Brimnes J, Muong C, Liu JH, Moran TM, Tappenden KA, Boros P, Mayer L. Induction of mucosal tolerance in Peyer's patch-deficient, ligated small bowel loops . J Clin Invest 2005 Aug; 115(8): 2234-2243.

Brimnes J, Allez M, Dotan I, Shao L, Nakazawa A, Mayer L. Defects in CD8+ regulatory T cells in the lamina propria of patients with inflammatory bowel disease . J Immunol 2005 May 1; 174(9): 5814-5822.

Perera L, Shao L, Patel A, Evans K, Meresse B, Blumberg R, Geraghty D, Groh V, Spies T, Jabri B, Mayer L. Expression of nonclassical class I molecules by intestinal epithelial cells. Inflamm Bowel Dis 2007 Mar; 13(3): 298-307.