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Wajahat Mehal, MD, DPhil

Professor of Medicine (Digestive Diseases)
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Additional Titles

Director of Yale Weight Loss Program

Director of Yale Fatty Liver Disease Program

Contact Info

Yale School of Medicine

Department of Medicine (Digestive Diseases), P.O. Box 208019

New Haven, CT 06520-8019

United States

About

Titles

Professor of Medicine (Digestive Diseases)

Director of Yale Weight Loss Program; Director of Yale Fatty Liver Disease Program

Biography

Wajahat Mehal MD, DPhil, is Professor of Medicine in Digestive Diseases, and Director of the Yale Fatty Liver Disease Program and the Yale Metabolic Health and Weight Loss Program.

Appointments

Other Departments & Organizations

Education & Training

Fellow
Yale New Haven Hospital (2001)
Resident
Yale New Haven Hospital (1996)
DPhil
University of Oxford (1993)
MD
University of Oxford (1990)

Research

Overview

Sterile Inflammation: Inflammation occurs in response to tissue injury even in the absence of signals from pathogens. There are numerous examples of this, from soft tissue swelling after trauma to the inflammatory infiltrate after a myocardial infarction. In the liver a number of clinically important conditions have a significant sterile inflammatory component. These include drug induced liver injury, alcoholic, and non-alcoholic liver disease. We have recently identified a two signals pathway consisting of activation of TLR9 by DNA from apoptotic self cells, and also activation of the inflammasome pathway. In addition we have found that the cheap and safe anti-inflammatory drug aspirin can inhibit the TLR9 mediated pathway. We are expanding these findings to test their general applicability to a wide range of liver diseases and also to further identify the role of up-stream activating steps including nuclear DNA, and metabolites of the uric acid pathway.

Liver Fibrosis: The hepatic stellate cell (HSC) is recognized as central to the development of liver fibrosis. We explored the paradigm that signals from dying cells result in HSC activation, and demonstrated that adenosine, which accumulates in conditions of tissue injury and inflammation, results in HSC activation. Interestingly in addition to up-regulating pro-fibrotic genes, adenosine also inhibits cytosolic calcium fluxes resulting in loss of HSC chemotaxis and contractility. We are currently examining other functional consequences of adenosine on HSC.

Liver Immunology: Antigens presented in the liver generate a suboptimal immune response often resulting in their chronic persistence (immune tolerance). This occurs clinically with tolerance to food antigens, to allo-antigens after transplantation, and to viral antigens during chronic infection with hepatitis viruses B and C. Despite these long-standing observations, it was recently realized that the healthy liver contains a large number of T cells (between 4-8 x 106 per gram of tissue). In this population conventional CD8+ T cells, and NK-T cells are over-represented, have an activated phenotype, and are undergoing cell cycle. We are interested in defining the interactions that occur between the healthy liver and the immune system during immune homeostasis, acute viral infections, and presentation of allo-antigens. We have shown that the healthy liver retains activated CD8+ T cells flowing through it. This retention is mediated mostly by hepatic ICAM-1 on Kupffer cells, and a proportion of the retained CD8+ T cells are undergoing apoptosis in the liver. Current work is focusing on the fate of activated CD8+ T cells when specific peptide is present in the liver, and also the ability of the liver to prime naive CD8+ T cells.

Medical Subject Headings (MeSH)

Digestive System Diseases; Fibrosis; Hepatitis; Inflammation; Liver; Weight Loss; Weight Reduction Programs

Research at a Glance

Yale Co-Authors

Frequent collaborators of Wajahat Mehal's published research.

Publications

2024

2023

Clinical Trials

Current Trials

Academic Achievements & Community Involvement

  • honor

    Fellow

Clinical Care

Overview

Wajahat Mehal MD, DPhil, is Professor of Medicine in Digestive Diseases, and Director of the Yale Fatty Liver Disease Program and the Yale Metabolic Health and Weight Loss Program.

He cares for patients with all liver diseases in the outpatient and inpatient setting, and particularly focuses on the areas of non-alcoholic and alcoholic fatty liver disease. He is also trained in obesity medicine and endobariatrics, managing patients by providing the full range of weight loss interventions, which include nutrition, medications, meal replacement, endobariatrics, and referrals to bariatric surgery.

In addition, he has an active NIH-funded translational research program in the areas of inflammation and fibrosis.

Clinical Specialties

Obesity Medicine; Gastroenterology; Hepatology

Fact Sheets

Board Certifications

  • Transplant Hepatology

    Certification Organization
    AB of Internal Medicine
    Latest Certification Date
    2020
    Original Certification Date
    2006
  • Gastroenterology

    Certification Organization
    AB of Internal Medicine
    Latest Certification Date
    2023
    Original Certification Date
    2001

Yale Medicine News

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Contacts

Appointment Number
Clinic Fax Number
Mailing Address

Yale School of Medicine

Department of Medicine (Digestive Diseases), P.O. Box 208019

New Haven, CT 06520-8019

United States

Administrative Support

Locations

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