Kronenberg Lab

Kronenberg Lab

"My dad always wanted to be a weather forecaster. He was fascinated by atmospheric changes and studied books on meteorology. As a boy, he taught me a lot about the forces of nature and instilled in me intense curiosity and a sense of wonder that I think eventually led to my career in science." — Mitchell Kronenberg, Ph.D. // President & Chief Scientific Officer
Division of Developmental Immunology


Mitchell Kronenberg, Ph.D., and his team study T cells – white blood cells responsible for recognizing and responding to foreign invaders, such as microbes. The laboratory focuses on a subset of T cells, that recognize glycolipids, or combinations of sugar and fat. Their research seeks to investigate how these T cells, called natural killer T cells (NKT), survive, grow, and regulate other immune cell types.
NKT cells apparently regulate a variety of immune responses, including the response to tumors and certain infectious agents. They also assist in the prevention of autoimmune diseases, such as diabetes (an immune attack on the pancreas) and multiple sclerosis (an immune attack on the nerves). The NKT cells respond rapidly and help other cells become activated. A glycolipid that activates these cells is currently in clinical trials in Australia, Japan, and Europe for treatment of metastatic cancer and hepatitis C virus infection.
A second area of research is the development of inflammatory bowel diseases (IBD) and an immune-mediated disease of the intestine, which include Crohn’s disease and ulcerative colitis. The uncontrolled response of white blood cells in the intestine leads to chronic inflammation. Using experimental models they developed, Dr. Kronenberg and his team are identifying molecules responsible for causing this poorly regulated immune response in the digestive tract.

From The Lab

Jul 19, 2016

Two LJI scientists selected to join the Mucosal Immunology Studies Team (MIST)

May 7, 2016 // NPR

When pregnant women get flu shots, babies are healthier

Feb 22, 2016 // San Diego Business Journal

Dr. Mitchell Kronenberg named "Most Admired CEO" by the San Diego Business Journal

Jan 25, 2016 // San Diego Business Journal

The Most Admired CEO Awards

Nov 23, 2015

Mitchell Kronenberg elected Fellow of the American Association for the Advancement of Science

Kronenberg Lab


Nat Immunol

Innate-like functions of natural killer T cell subsets result from highly divergent programs

Engel I, Seumois G, Chavez L, Samaniego-Castruita D, White B, Chawla A, Mock D, Vijayanand P, Kronenberg M.
J Exp Med

CD1d-restricted peripheral T cell lymphoma in mice and humans

Proc Natl Acad Sci USA

Phospholipid signals of microbial infection for the human immune system

Kronenberg M, Zhao M
Biomed J

Antigen specificity of invariant natural killer T-cells

Birkholz AM, Kronenberg M
Cytometry Part A

OMIP-030: Characterization of human T cell subsets via surfacr markers

Wingender G, Kronenberg M
Journal of Immunology

Selective conditions are required for the induction of invariant NKT cell hyporesponsiveness by antigenic stimulation

Wingender G, Birkholz AM, Sag D, Farber E, Chitale S, Howell AR, Kronenberg M

NKT10 cells: a novel iNKT cell subset

Wingender G, Sag D, Kronenberg M
Journal of Immunology

A novel glycolipid antigen for NKT cells that preferentially induces IFN-γ production

Birkholz AM, Girardi E, Wingender G, Khurana A, Wang J, Zhao M, Zahner S, Illarionov PA, Wen X, Li M, Yuan W, Porcelli…
Nature Immunology

A new mouse strain for the analysis of invariant NKT cell function

Chandra S, Zhao M, Budelsky A, de Mingo Pulido A, Day J, Fu Z, Siegel L, Smith D, Kronenberg M
Journal of Biological Chemistry

Lipid and carbohydrate modifications of α-galactosylceramide differently influence mouse and human type I natural killer T cell activation

Birkholz A, Nemčovič M, Yu ED, Girardi E, Wang J, Khurana A, Pauwels N, Farber E, Chitale S, Franck RW, Tsuji M,…
Journal of Biological Chemistry

The alpha and omega of galactosylceramides in T cell immune function

Birkholz AM, Howell AR, Kronenberg M
Journal of Immunology

Invariant NKT cells require autophagy to coordinate proliferation and survival signals during differentiation

Pei B, Zhao M, Miller BC, Véla, JL, Bruinsma MW, Virgin HW, Kronenberg M
Nature Communications

IL-10-producing intestinal macrophages prevent excessive antibacterial innate immunity by limiting IL-23 synthesis

Krause P, Morris V, Greenbaum JA, Park Y, Bjoerheden U, Mikulski Z, Muffley T, Shui JW, Kim G, Cheroutre H, Liu YC,…
Mucosal Immunology

Unique lamina propria stromal cells imprint the functional phenotype of mucosal dendritic cells

Vicente-Suarez I, Larange A, Reardon C, Matho M, Feau S, Chodaczek G, Park Y, Obata Y, Gold R, Wang-Zhu Y, Lena C,…

Therapeutic blockade of LIGHT interaction with herpesvirus entry mediator and lymphotoxin β receptor attenuates in vivo cytotoxic allogeneic responses

Del Rio ML, Fernandez-Renedo C, Scheu S, Pfeffer K, Shintani Y, Kronenberg M, Chaloin O, Schneider P. Rodriguez-Barbosa…

The identification of the endogenous ligands of natural killer T cells reveals the presence of mammalian α-linked glycosylceramides

Kain L, Webb B, Anderson BL, Deng S, Holt M, Constanzo A, Zhao M, Self K, Teyton A, Everett C, Kronenberg M, Zajonc DM,…
Journal of Clinical Investigation

IL-10-producing NKT10 cells are a distinct regulatory invariant NKT cell subset

Sag D, Krause P, Hedrick CC, Kronenberg M, Wingender G
Journal of Immunology

When less is more: T lymphocyte populations with restricted antigen receptor diversity

Kronenberg M

αβT cell receptors expressed by CD4(-)CD8αβ(-) intraepithelial T cells drive their fate into a unique lineage with unusual MHC reactivities

Mayans S, Stepniak D, Palida SF, Larange A, Dreux J, Arlian BM, Shinnakasu, Kronenberg M, Cheroutre H, Lambolez F
Nature Communications

Jarid2 is induced by TCR signalling and controls iNKT cell maturation

Pereira RM, Matrinez GJ, Engel I, Cruz-Guilloty F, Barboza BA, Tsagaratou A, Lio CW, Berg LJ, Lee Y, Kronenberg M,…

Synthesis of a 2"-deoxy-β-GalCer

Thakur MS, Khurana A, Kronenberg M, Howell AR

The tumor necrosis factor family member TNFSF14 (LIGHT) is required for resolution of intestinal inflammation in mice

Krause P, Zahner SP, Kim G, Shaikh RB, Steinberg MW, Kronenberg M
Nature Immunology

Protein C-η controls CTLA-4-mediated regulatory T cell function

Kong KF, Fu G, Zhang Y, Yokosuka T, Casas J, Canonigo-Balancio AJ, Becart S, Kim G, Yates JR 3rd, Kronenberg M, Saito…
Nephrology Dialysis Transplantation

Invariant natural killer T cells are depleted in renal impairment and recover after kidney transplantation

Peukert K, Wingender G, Patecki M, Wagner S, Schmitt R, Ge S, Schwarz A, Kronenberg M, Haller H, von Vietinghoff S
Immune Network

HVEM is a TNF receptor with multiple regulatory roles in the mucosal immune system

Shui JW, Kronenberg M
Journal of Immunology

Distinct requirements of activation of NKT and NK cells during viral infection

Tyznik AJ, Verma S, Wang Q, Kronenberg M, Benedict CA

Immunology: oiling the wheels of autoimmunity

Kronenberg M, Havran WL
Clinical and Experimental Immunology

Escherichida coli infection induces autoimmune cholangitis and anti-mitochondrial antibodies in (NOD).B6 (Idd10/Idd18) mice

Wang JJ, Yang GX, Zhang WC, Lu L, Tsuneyama K, Kronenebrg M, Véla JL, Lopez-Hoyos M, He XS, Ridgway WM, Leung PS,…
PLoS One

Autoimmunity-associated LYP-W620 does not impair thymic negative selection of autoreactive T cells

Wu DJ, Zhou W, Enouz S, Orrú V, Stanford SM, Maine CJ, Rapini N, Sawatzke K, Engel I, Fiorillo E, Sherman LA,…
PLoS One

Helicobacter pylori cholesteryl α-glucosides contribute to its pathogenicity and immune response by natural killer T cells

Ito Y, Vela JL, Matsumura F, Hoshino H, Tsynik A, Lee H, Girardi E, Zajonc DM, Liddington R, Kobayashi M, Bao X,…
Journal of Clinical Investigation

TSC1 regulates the balance between effector and regulatory T cells

Park Y, Jin HS, Lopez J, Elly C, Murai M, Kronenberg M, Liu YC
PLoS One

BTLA interaction with HVEM expressed on CD8(+) T cells promotes survival and memory generation in response to a bacterial infection

Steinberg MW, Huang Y, Wang-Zhu Y, Ware CF, Cheroutre H, Kronenberg M
Journal of Infection and Chemotherapy

The role of invariant natural killer T cells in microbial immunity

Kinjo Y, Kitano N, Kronenberg M
PLoS Biology

Production of α-galactosylceramide by a prominent member of the human gut microbiota

Wieland Brown LC, Penaranda C, Kashyap PC, Williams BB, Clardy J, Kronenberg M, Sonneburg JL, Comstock LE, Bluestone…
Nature Immunology

A 'GEM' of a cell

Kronenberg M, Zajonc DM
Proceedings of the National Academy of Sciences of the United States of America

Targeted delivery of lipid antigen to macrophages via the CD169/sialoadhesin endocytic pathway induces robust invariant natural killer T cell activation

Kawasaki N, Vela JL, Nycholat CM, Rademacher C, Khurana A, van Rooijen N, Crocker PR, Kronenberg M, Paulson JC
Journal of Immunology

Exosome-like nanoparticles from intestinal mucosal cells carry prostaglandin E2 and suppress activation of liver NKT cells

Deng ZB, Zhuang X, Ju S, Xiang X, Mu J, Liu Y, Jiang H, Zhang L, Mobley J, McClain C, Feng W, Grizzle W, Yan J, Miller…
Nature Immunology

Transcriptional reprogramming of mature CD4+ helper T cells generates distinct MHC class II-restricted cytotoxic T lymphocytes

Mucida D, Husain MM, Muroi S, van Wijk F, Shinnakasu R, Naoe Y, Reis BS, Huang Y, Lambolez F, Docherty M, Attinger A,…
Gut Microbes

HVEM: an unusual TNF receptor family member important for mucosal innate immune responses to microbes

Shui JW, Kronenberg M
Journal of Immunology

A novel role for IL-27 in mediating the survival of activated mouse CD4 T lymphocytes

Kim G, Shinnakasu R, Saris CJ, Cheroutre H, Kronenberg M
Journal of Immunology

ATP-binding cassette transporter G1 intrinsically regulates invariant NKT cell development

Sag D, Wingender G, Nowyhed H, Wu R, Gebre AK, Parks JS, Kronenberg M, Hedrick CC

The transcription factor Th-POK negatively regulates Th17 differentiation in Vα14i NKT cells

Engel I, Zhao M, Kappes D, Taniguchi I, Kronenberg M

Intestinal mucus-derived nanoparticle-mediated activation of Wnt/β-catenin signaling plays a role in induction of liver natural killer T cell anergy in mice

Deng ZB, Zhuang X, Ju S, Xiang X, Mu J, Wang Q, Jiang H, Zhang L, Kronenberg M, Yan J, Miller D, Zhang HG

HVEM signalling at mucosal barriers provides host defence against pathogenic bacteria

Shui JW, Larange A, Kim G, Vela JL, Zahner S, Cheroutre H, Kronenberg M

Intestinal microbes affect phenotypes and functions of invariant natural killer T cells in mice

Wingender G, Stepniak D, Krebs P, Lin L, McBride S, Wei B, Braun J, Mazmanian SK, Kronenberg M
Annals of the New York Academy of Sciences

Interplay between carbohydrate and lipid in recognition of glycolipid antigens by natural killer T cells

Pei B, Vela JL, Zajonc D, Kronenberg M
Journal of Immunology

Neutrophilic granulocytes modulate invariant NKT cell function in mice and humans

Wingender G, Hiss M, Engel I, Peukert K, Ley K, Haller H, Kronenberg M, von Vietinghoff S
Current Opinion in Immunology

Making memory at birth: understanding the differentiation of natural killer T cells

Engel I, Kronenberg M
Chemistry & Biology

Glycolipids that elicit IFN-biased responses from natural killer T cells

Tyznik AJ, Farber E, Girardi E, Birkholz A, Li Y, Chitale S, So R, Arora P, Khurana A, Wang J, Porcelli SA, Zajonc DM,…
PLoS Biology

Unique interplay between sugar and lipid in determining the antigenic potency of bacterial antigens for NKT cells

Girardi E, Yu ED, Li Y, Tarumoto N, Pei B, Wang J, Illarionov P, Kinjo Y, Kronenberg M, Zajonc DM
Nature Immunology

Mucosal memory CD8(+) T cells are selected in the periphery by an MHC class I molecure

Huang Y, Park Y, Wang-Zhu Y, Larange A, Arens R, Bernardo I, Olivares-Villagomez D, Herndler-Brandstetter D, Abraham N,…
Proceedings of the National Academy of Sciences of the United States of America

Cooling the fires of inflammation

Kim G, Kronenberg M
Journal of Molecular Medicine-JMM

Fibrocyte-like cells recruited to the spleen support innate and adaptive immune responses to acute injury or infection

Kisseieva T, von Kockritz-Blickwede M, Reichart D, McGillvray SM, Wingender G, Kronenberg M, Glass CK, Nizet V, Brenner…
Nature Immunology

Invariant natural killer T cells recognize glycolipids from pathogenic gram-positive bacteria

Kinjo Y, Illarionov P, Vela JL, Pei B, Girardi E, Li X, Li Y, Imamura M, Kaneko Y, Okawara A, Miyazaki Y, Gomez-Velasco…
Journal of Experimental Medicine

Invariant NKT cells are required for ariway inflammation induced by house dust extracts

Wingender G, Rogers P, Batzer G, Lee MS, Bai D, Khurana A, Kronenberg M, Horner AA
Journal of Immunology

Hepatic stellate cells function as regulatory bystanders

Ichikawa S, Muchida D, Tyznik A, Kronenberg M, Cheroutre H
Journal of Leukocyte Biology

Regulation of inflammation, autoimmunity, and infection immunity by HVEM-BTLA signaling

Shui JW, Steinberg MW, Kronenberg M
Journal of Immunology

Diverse endogenous antigens for mouse natural killer T cells: self-antigens that are not glycosphingolipids

Pei B, Speak AO, Shepherd D, Buters T, Cerundolo V, Platt FM, Kronenberg M
Advances in Immunology

Activation and function of iNKT and MAIT cells

Chandra S, Kronenberg M
Journal of Immunology

Antigen-dependent versus -independent avtication of invariant NKT cells during infection

Holzapfel KL, Tyznik AJ, Kronenberg M, Hogquist KA

Invariant natural killer T cells: front line fighters in the war against pathogenic microbes

Crosby CM, Kronenberg M

Natural Killer T cells

Engel I, Kronenberg M
Current Topics in Microbiology and Immunology

Transcriptional control of the development and function of Vα14i NKT cells

Engel I, Kronenberg M
Waltham: Academic Press

The roll of natural killer T cells in autoimmune diseases

Wingender G, Kronenberg M
Circulation Research

Interleukin-27 receptor limits atherosclerosis in Ldlr-/- mice

Koltsova EK, Kim G, Lloyd KM, Saris CJ, von Vietinghoff S, Kronenberg M, Ley K
PLoS One

Interruption of CXCL 13-CXCR5 axis increases upper genital tract pathology and activation of NKT cells following chlamydial genital infection

Jiang J, Karimi O, Ouburg S, Champion CI, Khurana A, Liu G, Freed A, Pleijster J, Rozengurt N, Land JA, Surcel HM,…
Oxford: Elsevier Academic Press

Mucosal-resident T lymphocytes with invariant antigen receptors

Kronenberg M, Lantz O

Principal Investigator


Mitchell Kronenberg, Ph.D.

President & Chief Scientific Officer

Dr. Kronenberg is an internationally recognized scientist and one of the most highly cited immunologists in the world. This distinction is held by less than one half of one percent of all publishing scientific authors. Dr. Kronenberg was appointed President of La Jolla Institute for Allergy and Immunology (LJI) in September 2003. In addition to his executive duties, he serves as Chief Scientific Officer and conducts an active research program.

He received his Ph.D. from the California Institute of Technology in 1983, and stayed on to complete his postdoctoral work before joining the faculty of the UCLA School of Medicine in 1986. At UCLA, he rose through the ranks to full professor. In 1997, he came to La Jolla Institute to head the Division of Developmental Immunology, a position he held for 14 years, before stepping down recently to devote more time to his duties as President and Chief Scientific Officer.

Over the years, Dr. Kronenberg has received many major awards, most recently a prestigious Merit Award for scientific achievement from the National Institutes of Health. He has also been a Burroughs Wellcome Fund Visiting Professor at Harvard University and recently was asked to deliver the Joseph S. Ingraham immunology lecture at the Indiana University School of Medicine.

Lab Members


Shilpi Chandra

Postdoctoral Fellow

I obtained bachelor degree in Microbiology from Barkatullah University, India and later went on to do masters in Life Sciences from Devi Ahilya University, India. I then did PhD from ICGEB, New Delhi and Devi Ahilya University in Life Sciences. I am working as a Post-Doctoral Fellow at La Jolla Institute for Allergy and Immunology since January 2011.

Research Focus:
My research focus here is to understand mechanism of Cd1d-dependent antigen presentation. To understand this at a global level, we have employed whole genome RNA interference (RNAi) screening. After several rounds of validation, functional classification and gene expression analysis, we have identified key genes likely to be involved in CD1d antigen presentation. Now I am trying to understand the specific mechanism by which these genes affect CD1d dependent antigen presentation.

Career Goals:

I want to pursue my career in scientific research involving host- pathogen interactions in human disease.


Catherine Crosby

Postdoctoral Fellow

I graduated from the University of Illinois at Urbana-Champaign in 2010 with a B.S. degreein Molecular and Cellular Biology.  I then completed my Ph.D. in Virology and Gene Therapy under the mentorship of Dr. Michael Barry at the Mayo Graduate School in Rochester, MN in 2015.  I began working as a postdoc in the Kronenberg laboratory in July 2015.

Research focus:  
My research projects are focused on how invariant natural killler T (iNKT) cells function in the lungs during Streptococcus pneumoniae infection.  I am interested in gaining a better understanding of why this class of innate lymphocytes are so critical for protection against S. pneumoniae in mice, with the ultimate goal of harnessing the potential of these cells for human therapeutics.  

Career goals:  
I plan to pursue a career in academic research in the fields of infectious disease and vaccine development.

Christopher Dillingham

Visiting Scientist


Isaac Engel


I have a PhD in Biology from UCSD in 1989, and have worked as a post-doc in the lab of Richard Klausner at NIH from 1989-1993, followed by a post-doc and later a Research Scientist position in the lab of Cornelis Murre at UCSD.  I have been in the Kronenberg lab since 2004. 

My research has focused on the development and function of invariant NKT cells, with particular emphasis on the characterization of functional subsets of these cells, and the factors that dictate their differentiation.


Nadine Hartmann


My fascination for bacterial pathogens and their relation to hosts started at the Martin Luther University in Halle, Germany where I graduated in 2010 with a Master degree in Biology and obtained my Ph.D. in Genetics and Molecular Biology in 2013. I began working as a postdoctoral fellow in Dr. Kronenberg’s lab at the La Jolla Institute for Allergy and Immunology in May 2015.

Research focus:
My research focuses on the interaction of the human pathogen Streptococcus pneumoniae with its host during pulmonary infection. I would like to understand how S. pneumoniae stimulates T cell responses in mice and how those different mechanisms contribute to pulmonary disease.


Kaori Hitomi


I graduated from University of Tsukuba in 2007 with a B. S. degree in Biological science. I obtained my M.S. in medical science in 2009 and my Ph.D. in medical science in 2012 from University of Tsukuba. Between 2013 and 2015 I trained as a postdoctoral fellow in the group of Dr. Akira Shibuya at University of Tsukuba. I joined the Kronenberg laboratory as a postdoc in April 2015.

Research Focus:
My research focuses on the Involvement of herpes virus entry mediator (HVEM) in bacterial infection of the lung. 

Career Goals: 
My goal is to become an independent researcher who contribute to the understanding how innate immune responses regulate adaptive immune responses.


Archana Khurana

Lab manager

I graduated from Guru Nanak Dev University, India in 1989 with a B.S. degree in Biological Sciences. I obtained my M.S Chemistry degree from Guru Nanak Dev University in 1991. I did Bachelor of Education in 1992 from Government College of Education, India. I was working as a High School teacher in India from 1993 to 1997. I joined as a Research Associate in Dr. Blaber laboratory at Florida State University, Tallahassee in 1998. I began working as a Research Associate/ Lab Manager in Dr. Kronenberg Laboratory at La Jolla Institute for Allergy and Immunology in July 1999.

Research Focus:
My research projects are focused on detection of antigenicity of complex glycolipids that trigger cytokines production by NKT cells.

Career Goals:
I plan to pursue a career in scientific research focused in NKT cells which assist in prevention of autoimmune diseases such as diabetes, multiple sclerosis and tumors.


Venitia C Morris

Research Technician III

I graduated from the University of San Diego in 2004 with a B.S. degree in Biology. I began working as a research technician in the Kronenberg laboratory at the La Jolla Institute for Allergy and Immunology in December 2008.

My primary focus has been in the area of mucosal immunology and inflammatory bowel disease. I have helped to generate various mouse models inducing colitis to identify methods of immune-mediated inflammation and tissue destruction in the gut and to explore regulatory pathways that can prevent disease pathogenesis. By examining the importance of regulatory T cells in anti-inflammation we have found a potential therapeutic effect of IL-10 producing intestinal macrophages for IBD patients.

Masako Murai

Visiting Scientist


Laibin Ren

Graduate Student

I graduated from Sichuan University in 2013 with a B.S. degree in Basic Medicine in China. In the same year I was enrolled into Sichuan University's PhD Program, majoring in Pathology and Pathophysiology. I began working as an exchange PhD student in the Kronenberg’s laboratory in August 2015.

Research Focus:
Currently I am focusing on deciphering the HVEM signaling in epithelial cell by employing CRISPR-Cas9.

Career Goals:
I plan to pursue a career in scientific research focusing on the roles of innate immunity in host defending against microbes.


Gooyoung Seo

Postdoctoral Fellow

I received my Ph.D from Kangwon National University (KNU), S. Korea in 2008. I did my postdoctoral training at same university from 2008 to 2010. I was a research professor at Kangwon National University from 2010 to 2012. I worked as a visiting scientist at the University of Chicago from 2012 to 2013. I joined the laboratory of Dr. Kronenberg at the La Jolla Institute for Allergy and Immunology as postdoctoral fellow in 2014.

Research Focus:
My research focuses on the role of the herpesvirus entry mediator (HVEM) of by Innate Lymphoid Cells (ILC) and intraepithelial lymphocytes (IEL) in the Intestine.

Career Goals:
I plan to a career in scientific research focused on intestinal immune regulation.

Robert Signer

Adjunct Professor

Mary Jean Sunshine

Visiting Scientist


Sonja Zahner

Postdoctoral Fellow

In 2004, I received my Diploma in Biology from the Julius Maximilians University in Germany and then started my Ph.D. in Immunology at the Academic Medical Center of the University of Amsterdam. While I obtained my PhD from the University of Amsterdam beginning of 2012, I already started working as a postdoc in the Kronenberg laboratory at the La Jolla Institute for Allergy and Immunology in June 2011.

Research Focus: 
My main interest is to study the role of Tumor Necrosis Super Family (TNFSF) members in mucosal immunity.  To this aim we generated new conditional knockout mouse strains, which are currently analyzed to unravel the mechanism of a recently discovered unexpected protective role of TNFSF14/LIGHT by our lab in an Inflammatory Bowel Disease (IBD)-like mouse model.

Career Goals:
I plan to pursue a career that is research oriented but not necessarily in academia.

Danhua Zhang

Visiting Scientist


Meng Zhao

Postdoctoral Fellow

I got my undergraduate degree in Biology in 2004 from Wuhan University in China and my PhD degree in Genes and Development in 2010 from University of Texas-Southwestern Medical Center in Dallas. I began my postdoctoral training in Dr. Kronenberg’s laboratory at the La Jolla Institute for Allergy and Immunology in 2011.

Research Focus:
My current research focuses on the discovery of new mechanisms that regulates the differentiation and development of iNKT cells.

Career Goals:
I plan to pursue a career in research, and ultimately to discover new ways to treat human diseases.

Kronenberg Lab

Research Projects

Our laboratory is interested broadly in the interface between the innate and adaptive immune systems, and the unique subsets of T lymphocytes that bridge these systems by adopting properties that are very characteristic of innate immune cells. One of these T cell subsets is comprised of the CD1d-reactive invariant natural killer T cells, and over the years we have studied the development, homeostasis, activation and regulation of function of these cells, as well as their specificity and the pathways leading to the processing and presentation of antigens by CD1d. Another unconventional T cell subset with some features of innate immune cells is the intestinal intraepithelial lymphocytes (IEL) that express CD8αα homodimers, but neither CD4 nor CD8αβ. Our fascination with these cells has led us to explore more generally the regulation of the mucosal immune response, with a strong emphasis on events leading to the dysregulation of this response and colitis. The research on colitis models has focused particularly on the roles of cytokines such as IL-10 and IL-27, and members of the TNF super family and their various receptors.

NKT Cell Immunology

Vα14 invariant NKT (Vα14 iNKT) cells are a population of T lymphocytes that have several unique characteristics; many of these are related to their ability to function similarly to cells of the innate as opposed to the adaptive immune system. Like conventional T cells that express an αβ TCR, their development is initiated by positive selection at the CD4, CD8 DP developmental stage in the thymus. However, Vα14 iNKT cell selection is dependent upon expression of CD1d, a MHC class I-like protein that presents lipids rather than peptides, by other DP thymocytes. As the name implies, Vα14 iNKT cells express a TCR with extremely limited diversity, consisting in mice of an invariant alpha chain (Vα14-Jα18) generally paired with beta chains using Vβ8.2, 7 or 2. Vα14 iNKT cells are also distinguished by their tendency to express NK receptors, which is the underlying reason for the name "NKT cells". They also express T cell activation markers, even (and to a great extent) in germ free mice, hence they appear to develop to become a natural memory cell population based on some type of internal antigen(s). Their tissue distribution also is unusual, as they are found in large numbers in the liver, but they are relatively scarce in lymph nodes. These cells exhibit the unique property of being able to respond very rapidly to antigenic challenge without restimulation, immediately producing a broad spectrum of cytokines, including both IFNγ and IL-4. Vα14 iNKT cells have been found to be important modulators of the response to infectious agents, autoimmunity, tolerance induction, and the response to cancers. Humans have a homologous population with nearly identical specificity, and although the cells tend to be more frequent in mice than humans, clinical trials are underway based on activating human iNKT cells to stimulate antitumor responses. It is thus important to learn more about the properties of these cells and how they can be manipulated to modulate immunity.

One active area of interest of our laboratory concerns the range of antigens to which Vα14 iNKT cells can respond. Previous data from our laboratory and others have determined that Vα14 iNKT cells respond to glycolipids with defined structures, including a ceramide lipid backbone and an α-linked hexose sugar, when presented by CD1d. More recent work has shown that glycolipids capable of stimulating Vα14 iNKT cells are found in several types of bacteria, including the relatively nonpathogenic and ubiquitous species of Sphingomonas organisms, and the spirochete Borrelia burgdorferi, which causes Lyme disease. The antigen in this latter case has a diacyl glycerol lipid rather than a ceramide lipid, a type of lipid more common among microrganisms. Furthermore, mice that lack Vα14 iNKT cells have been shown to be more susceptible to arthritis induced by Borrelia infection. These data suggest that a primary function of Vα14 iNKT cells may be to control bacterial infections. Our laboratory is continuing its efforts to characterize compounds that can act as agonists for the invariant TCR of Vα14 iNKT cells, and to further define the role(s) of these cells in bacterial defense. Recent evidence indicates that gram positive and highly pathogenic bacteria also have antigens for iNKT cells.

Our laboratory has also uncovered evidence for an indirect, antigen-independent mechanism of activation of Vα14 iNKT cells. These cells were shown to respond in vivo to agonists of the TLR family, and this response was dependent on activation of DCs and on IL-12 derived from the activated DCs signaling the Vα14 iNKT cells. It was not inhibited by blockade of CD1d, however, suggesting (self) antigen recognition is not required. Interestingly, unlike the unpolarized cytokine response observed upon stimulation with TCR agonists, Vα14 iNKT cells activated by this indirect, TLR/IL-12-dependent pathway secrete only IFNγ in significant quantities. We have recently shown that this antigen-independent pathway is activated in mice by infection with CMV, and is important for virus resistance in mouse strains that lack a strong NK cell response to CMV. We are continuing our efforts to understand the role of this pathway in the response to viruses and other pathogens.

Long-term efforts in our research group have been directed towards uncovering the unique pathway for the differentiation of Vα14 iNKT cells, which require a different selecting cell type in the thymus that probably imprints the activated phenotype in these cells, including the opening of the gene loci encoding IL-4 and IFNγ. We are investigating the roles of various transcription factors, kinases, and molecules involved in intracellular vesicular traffic in order to understand the differentiation of Vα14 iNKT cells.

We have also have adopted a number of lines of study into the regulation of cytokine production and effector cell responses such, as cytotoxicity, in the response of Vα14 iNKT cells to glycolipid antigens or IL-12 from activated DCs. These include examinations of the effect of antigen structure on the spectrum of cytokines produced after either in vivo or in vitro stimulation, as well as the ability to anergize Vα14 iNKT cells in terms of cytokine production and effector function by prior antigen challenge. We have also initiated studies of the regulation of cytokine gene expression in these cells. We hope that these efforts will allow us to identify means by which the response of iNKT cells can be manipulated to effect desired immunologic outcomes in possible therapeutic applications.

Mucosal Immunology and IBD

A major area of research in our laboratory is the regulation of mucosal immunity. We have collaborated extensively with the Hilde Cheroutre laboratory at our Institute on several projects, including investigation of the function of intestinal intraepithelial lymphocytes (IEL), particularly those that exclusively express CD8αα homodimers. We have also studied the function of the TL antigen, a nonclassical MHC class I antigen molecule highly expressed in the intestine that interacts with CD8αα homodimers.

Additionally, we have assisted with studies showing the vitamin A metabolite retinoic acid promotes the generation of regulatory T cells (Treg) and inhibits proinflammatory Th17 cell differentiation. However, the great majority of our work in this area is related to the development of inflammatory bowel diseases (IBD), immune-mediated diseases of the intestine that include Crohn's disease and ulcerative colitis. These are chronic immune disorders in which an uncontrolled response of mucosal immune cells leads to severe inflammation in the intestine. Using experimental colitis mouse models that resemble different aspects of human IBD, we have been investigating the processes and molecules responsible for causing severe inflammation in the digestive tract.

Subsets of CD4+ T lymphocytes play pivotal roles both in initiating the inflammatory process, by secreting pro-inflammatory cytokines, and by preventing inflammation, in part by secreting regulatory cytokines such as IL-10 and TGFβ. T helper 1 (Th1) lymphocytes promote inflammation by secreting inflammatory cytokines such as interferon (IFN)γ and tumor necrosis factor (TNF). Additional CD4+ T cell types have been discovered, including those producing IL-17 (Th17 cells), that likely participate in the induction of IBD. The generation of these T cell subsets depends on the action of cytokines such as IL-6, IL-12 and IL-23, produced mostly by cells of the innate immune system. An active area of investigation in our lab concerns the role of another cytokine produced mostly by innate immune cells, the IL-12 family member IL-27. Although originally described as a cytokine promoting Th1 responses, our work has uncovered diverse roles of this cytokine in the responses of both pathogenic T lymphocytes and Treg.

TNF is one of the most potent effector cytokines in the pathogenesis of autoimmune disorders, and blockade of TNF with anti-TNF antibodies is an effective treatment for many patients with IBD. However, in some of these patients, anti-TNF treatment efficacy is relatively modest. The basis underlying this non-responsiveness is unknown, but it is possible that other TNF family members may be involved in colitis pathogenesis. In collaboration with the Carl Ware laboratory, we have explored how a TNF-related molecule known as LIGHT (TNFSF-14), plays a vital role in regulating IBD pathogenesis. We showed that transgenic mice that constitutively express LIGHT develop multi-organ inflammation, including the intestine, suggesting LIGHT could contribute to IBD.

Our laboratory has also been investigating the role of the LIGHT receptor HVEM when its binds to a different partner, the B and T lymphocyte attenuator (BTLA). Interestingly, BTLA is not a TNF-family molecule, but is a member of the Ig-super family. We have recently found that HVEM expressed in a non-hematopoietic cell type is necessary to dramatically slow colitis induction in the T cell transfer model. HVEM attenuates disease by interacting with BTLA expressed by at least two cell types: CD4 T cells and a non-lymphoid cell type. Moreover, an agonistic anti-BTLA antibody prevented accelerated colitis in mice, implicating BTLA as a potential target for treatment of IBD. Current investigations focus on how BTLA expressed by different cell types attenuates disease. Our laboratory has assembled a comprehensive set of tools for doing this, including mice with conditional ablation of the Btla gene in different subsets of immune cells. Several studies are ongoing using the colitis transfer model, as well as an experimental mouse model in which colitis is induced by the pathogenic enterobacteria Citrobacter rodentium.

An important category of immune cells is the regulatory T lymphocytes (Treg), which act to suppress over exuberant immune responses. Patients with no regulatory T cells develop multi-organ inflammatory diseases, and problems with regulatory T cells could be an important contributing factor to IBD.

Treg express the forkhead box p3 (Foxp3) transcription factor, which is required for their regulatory function. Co-transfer of Treg with CD4+CD45RBhigh T cells into Rag-/- hosts can prevent or cure intestina;l inflammation. We have recently found that the capacity of Treg to mantain Foxp3 expression and anti-inflammatory function depends on the cytokine IL-10. Using the colitis transfer model, we showed that IL-10 produced by a subset of myeloid cells in the Rag-/- recipients is required for colitis suppression by transferred Treg. The Treg transferred into Il-10-/-Rag-/- mice expanded, but they failed to maintain Foxp3 expression and suppressive activity, indicating that Foxp3 expression is surprisingly unstable. Ongoing studies in the laboratory will determine what type of IL-10 producing cells are required to preserve Treg function in Rag-/- recipients. Furthermore, the laboratory is actively investigating how the interaction of IL-10 with the IL-10-receptor expressed on regulatory T cells controls Foxp3 expression and Treg function.