Cheroutre Lab

Cheroutre Lab

"Rather than figuring out how to treat disease, I’d like to understand how to prevent it. It would be a wonderful thing if we could stop terrible diseases before they have a chance to do any damage." — Hilde Cheroutre, Ph.D. // Division Head and Professor
Division of Developmental Immunology

Overview

Hilde Cheroutre, Ph.D., and her team are studying the development, function, and regulation of white blood cells, a type of T lymphocytes. The laboratory is investigating how the immune system provides protection at “interfaces,” or places where the outside world comes in contact with the inside of the body, such as skin, lungs, mouth, and the largest surface of all, the intestine.

Studying how the immune system works in the intestine is of particular interest because the immune system has to be able to distinguish pathogenic antigens from harmless food peptides and bacteria. The laboratory is investigating how the immune system succeeds in differentiating between the two and what causes the system to fail, allowing the antigens to invade the body.

The lab’s research has been expanded to studying immune memory cells that resist re-entering pathogens or cancer cells. Tumor cells produce tumor antigens, which are cell surface proteins that differ from the proteins expressed by the surrounding normal cells. White blood cells recognize and destroy these transformed cells. Some of these tumor-fighting white blood cells go on to become immune memory cells. These are long-lived cells that activate immediately when they re-encounter tumor antigens, in the case of metastasis or re-occurrence of the tumor.

Understanding the function of immune memory T cells will help in the development and improvement of effective vaccines. At the same time, the ability to specifically eliminate these cells is a key requirement in the therapeutic intervention against autoimmune diseases and the rejection and/or destruction of host tissue following transplantation.

From The Lab

Jul 19, 2016

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

Jan 24, 2013 // San Diego Union Tribune

La Jolla Institute identifies molecular switch enabling Immune cells to better fight disease

Jan 20, 2013

La Jolla Institute identifies molecular switch enabling immune cells to better fight disease

Cheroutre Lab

Publications

Arthritis Rheumatol

Critical role of fibroblast-like synoviocytes glycolytic metabolizm in rheumatoid arthritis

2016-01
Garcia-Carbonell R, Divakaruni AS, Lodi A, Vincente-Suarez I, Saha A, Cheroutre H, Boss GR, Tiziani S, Murphy AN, Guma M
Cancer Immunology Research

T-cell expression o fIL-10 is essential for tumor immune surveillance in the small intestine

2015-07
Dennis KL, Sasdalla A, Blatner NR, Wang S, Venkateswaran V, Gounari F, Cheroutre H, Weaver CT, Roers A, Egilmez NK,…
Nature Communications

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

2015-05
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

2015-01
Vicente-Suarez I, Larange A, Reardon C, Matho M, Feau S, Chodaczek G, Park Y, Obata Y, Gold R, Wang-Zhu Y, Lena C,…
Immunity

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

2014-08
Mayans S, Stepniak D, Palida SF, Larange A, Dreux J, Arlian BM, Shinnakasu, Kronenberg M, Cheroutre H, Lambolez F
Journal of Immunology

Negative selection of self-reactive chicken B cells requires B cell receptor signaling and is independent of bursal microenvironment

2014-04
Davani D, Pancer Z, Cheroutre H, Ratcliffe MJ
Nature

Themis sets the signal threshold for positive and negative selection in T-cell development

2013-12
Fu G, Casas J, Rigaud S, Rybakin V, Lambolez F, Brazostek J, Hoerter JA, Paster W, Acuto O, Cheroutre H, Sauer K,…
Seminars in Immunology

CD4 CTL: living up to the challenge

2013-11
Cheroutre H, Husain MM
PLoS One

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

2013-10
Steinberg MW, Huang Y, Wang-Zhu Y, Ware CF, Cheroutre H, Kronenberg M
Frontiers in Immunology

CD8αα expression marks terminally differentiated homan CD8+ T cells expanded in chronic viral infection

2013-08
Walker LJ, Marrinan E, Muenchhoff M, Ferguson J, Kloverpris H, Cheroutre H, Barnes E, Goulder P, Klenerman P
Immunity

T cell-derived protein S engages TAM receptor signaling in dendritic cells to control the magnitude of the immune response

2013-07
Carrera Silva EA, Chan PY, Joannas L, Errasti AE, Gagliani N, Bosurgi L, Jabbour M, Perry A, Smith-Chakmakova F, Mucida…
Nature Immunology

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

2013-03
Mucida D, Husain MM, Muroi S, van Wijk F, Shinnakasu R, Naoe Y, Reis BS, Huang Y, Lambolez F, Docherty M, Attinger A,…
Journal of Immunology

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

2013-02
Kim G, Shinnakasu R, Saris CJ, Cheroutre H, Kronenberg M
Nature

Adenoma-linked barrier defects and microbial products drive IL-23/IL-17-mediated tumour growth

2012-11
Grivennikov SI, Wang K, Muchida D, Stewart CA, Schnabl B, Jauch D, Taniguchi K, Yu GY, Osterreicher CH, Hung KE, Datz…
Journal of Immunology

Cutting edge: 4-1BB controls regulatory activity in dendritic cells through promoting optimal expression of retinal dehydrogenase

2012-09
Lee SW, Park Y, Eun SY, Madireddi S, Cheroutre H, Croft M
Mucosal Immunology

Got IELs?

2012-09
Cheroutre H, Huang Y
Nature

HVEM signalling at mucosal barriers provides host defence against pathogenic bacteria

2012-08
Shui JW, Larange A, Kim G, Vela JL, Zahner S, Cheroutre H, Kronenberg M
Diabetes

Following the fate of one insulin-reactive CD4 T cell: conversion into teffs and tregs in the periphery controls deiabetes in NOD mice

2012-05
Fousteri G, Jasinski J, Dave A, Nakayama M, Pagni P, Lambolez F, Juntti T, Sarikonda G, Cheng Y, Croft M, Cheroutre H,…
Science Signaling

Protein kinase C η is required for T cell activation and homeostatic proliferation

2011-12
Fu G, Hu J, Niederberger-Magnenat N, Rybakin V, Casas J, Yachi PP, Feldstein S, Ma B, Hoerter JA, Ampudia J, Rigaud S,…
Nature Immunology

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

2011-10
Huang Y, Park Y, Wang-Zhu Y, Larange A, Arens R, Bernardo I, Olivares-Villagomez D, Herndler-Brandstetter D, Abraham N,…
Journal of Experimental Medicine

Constitutive intestinal NF-κB does not trigger destructive inflammation unless accompanied by MAPK activation

2011-08
Guma M, Stepniak D, Shaked H, Spehlmann ME, Shenouda S, Cheroutre H, Vicente-Suarez I, Eckmann L, Kagnoff MF, Karin M
Nature Reviews Immunology

The light and dark sides of intestinal intraepithelial lymphocytes

2011-06
Cheroutre H, Lambolez F, Muchida D
Journal of Immunology

Hepatic stellate cells function as regulatory bystanders

2011-05
Ichikawa S, Muchida D, Tyznik A, Kronenberg M, Cheroutre H
Advances in Experimental Medicine and Biology

Crosstalk between adaptive and innate immune cells leads to high quality immune protection at the mucosal borders

2016-09
Cheroutre H, Huang Y
New York: Garland Science

Intraepithelial lymphocytes: unusual T cells at epithelial surfaces. In: Smith PD, MacDonald TT, Blumberg RS, editors.

2016-09
Cheroutre H
Annu Rev Immunol

Retinoic acid and retinoic acid receptors as pleiotropic modulators of the immune system

2016-05
Larange A, Cheroutre H

Principal Investigator

Dr.HildeCheroutre

Hilde Cheroutre, Ph.D.

Division Head and Professor

Dr. Cheroutre joined LIAI in 1998 and is currently Division Head and Professor in the Division of Developmental Immunology. Dr. Cheroutre’s research focuses on the selection, regulation and activation of different classes of T cells, such as regulatory and memory T cells.

Dr. Cheroutre received her Licentiate in Sciences from the State University of Ghent in Belgium in 1978. She received her Ph.D. from the same university in 1984, earning highest honors. That same year, Dr. Cheroutre began her postdoctoral work at the California Institute of Technology in Pasadena. In 1988, Dr. Cheroutre began a three-year stint working in the lab of Mitchell Kronenberg, Ph.D., current President and Chief Scientific Officer of LIAI, in the Department of Microbiology and Immunology at the University of California, Los Angeles. From 1991 to 1997, Dr. Cheroutre was co-director of UCLA’s Transgenic Mouse Facility.

Dr. Cheroutre has been awarded the NATO postdoctoral fellowship twice, as well as the Markey Foundation Postdoctoral Fellowship and the Cancer Research Coordinating Committee Fellowship from the State of California.

Lab Members

Savio Henrique De Souza Almeida

Intern

Alex Ghenassia

Postdoctoral Fellow

MohdMushtaqHusain

Mohd. Mushtaq Husain, Ph.D.

Instructor

Biosketch:
I am originally from India, did my Ph.D. (2010) at Sanjay Gandhi Postgraduate Institute of Medical Sciences (Lucknow, UP, India), studied cellular immunity among patients with acute Hepatitis E. Then, I moved to La Jolla Institute for Allergy and Immunology in March 2010 for my postdoctoral training.

Research Focus:
Differentiation and functions of cytotoxic CD4+ T effector cells (CD4 CTL). Recently, we established MHC class II restricted CD4 CTL as a separate effector subset. In brief, during post-thymic events, CD4+ T cells lose Th-lineage master transcription factor (ThPOK), terminate T helper genes transcription and de-repress the cytotoxicity-gene expression program. Currently, I am elucidating the mechanism of differentiation and their action. CD4 CTL appear to be a very important player in host immunity.

Career Goals:
I plan to keep working on CD4 CTL and find out whether CD4 CTL differentiation pathways will reveal the key for therapeutic interventions against inflammatory bowel disease, autoimmunity, and immunity against cancer and pathogens.

HitoshiIwaya

Hitoshi Iwaya, Ph.D.

Postdoctoral Fellow

Biosketch:
I obtained my Ph.D. in Nutritional Biochemistry from the Hokkaido University in March 2013. I began working in the Cheroutre laboratory at the La Jolla Institute for Allergy and Immunology in April 2013. I am interested in how intestinal intraepithelial T cells are regulated by intrinsic and extrinsic factors. My current focus is to show the importance of the reprogramming process of CD4 T cells to a functional CTL phenotype as a mechanism for the intestinal mucosal immune system to preserve optimal protective immunity.

Alex Larange, Pharm.D, Ph.D.

Postdoctoral Fellow

Biosketch:

  • Master degree in Clinical and Experimental Pharmacology [2004, Paris-Sud University]
  • Pharm.D. (Specialization: Industry) [2004, Paris-Sud University]
  • Adjunct assistant professor in Immunotoxicology [2004-2007, Paris-Sud University]
  • Ph.D. in Pharmaceutical Innovation [2008, Paris-Sud University]
  • Post-doctoral fellow in the laboratory of Hilde Cheroutre since 2009

Research focus:
My research projects are focused on the mechanisms involved in the regulation of the T cell receptor signaling pathways and their impact on the ability of CD8 T cells to exert their full cytotoxic potential against virus or intracellular bacteria, and to generate efficient immune memory, especially at the mucosal sites.

Chris Lena

Research Technician IV

After graduating from University of Delaware I moved to California and began working at LJI. I have been the Lab Manager for Hilde's lab for nearly 19 years and also work for Mitch's lab.

Nicholas Thiault

Postdoctoral Fellow

Yiran Wang-Zhu

Research Technician IV

Cheroutre Lab

Research Projects

My research has focused predominantly on T cell development and function and in understanding the regulatory mechanisms involved in controlling self-reactive T cells and T cell survival of activation induced cell death (AICD). In addition to the conventional positive selected T cells there are numerous other TCRaß+ T cells that do not conform to this common pool of T cells. These include NK T cells, CD25+ CD4+ regulatory T cells and the majority of the intraepithelial lymphocytes (IEL) in naïve animals. These non-standard T cell groups differ from the common antigen reactive T cells with regard to selection conditions as well as activation conditions that lead to distinct activation processes.

T CELLS

One large subgroup of these specialized T cells is encompassed by the IEL which are located in the epithelium of the small intestine in humans and mice. IEL are distinct from conventional T cells with regard to phenotype and function, with the great majority of the IEL being CD8+ cytotoxic T cells. Furthermore, in mice most of these CD8+ IEL exclusively express an aa homodimeric form of CD8 as opposed to the more typical CD8aß heterodimer expressed by CD8+ splenocytes. The CD8aa+ IEL population characteristically contains numerous TCR?d+ T cells, TCRaß CD8aa+ single positive cells, and various numbers of TCRaß+ double positive (DP) or CD4+ or CD8aβ+CD8aa+ IEL (our findings), as well as TCR negative cells, most of them with an NK like nature. CD8aa expression on T cells does not depend upon CD8ß expression in the thymus (our findings) while they do require ß2m dependent MHC class I expression for their differentiation and/or homeostasis. They are, however, much less dependent on TAP expression (our findings) and interestingly, these cells are present in mice that lack classical class I molecules (Kb and Db deficient mice) (our findings). All mucosal T cells typically have an activated effector/memory phenotype. Furthermore IEL harbor numerous potentially autoreactive T cells, as evidenced by the presence of cells expressing forbidden Vßs reactive with autologous, retroviral-encoded superantigens. Conventional T cells are positively selected by weak interactions with self-peptides. By contrast, we have shown, using several transgenic systems in which a TCR transgene and an agonist for that TCR are co-expressed, that thymocytes expressing an autoreactive TCRaß are positively selected in an a-CPM dependent way by the thymus and preferentially give rise to CD8aa expressing T cells in the gut. We have called this process "agonist selection" to distinguish it from conventional positive selection. This selection of CD8aa expressing T cells can occur even with a class II restricted TCR indicating that expression of CD8aa on mature T cells does not imply MHC class I restriction of their TCRs. This finding of thymus origin goes against the general belief that CD8aa+ TCRaß+ IEL have developed extra-thymically.

In general our studies have led to a revision of the paradigm of thymic selection, requiring the addition of agonist selection along the conventional selection pathway as a mechanism to educate and select diverse subpopulations of specialized T cells. We have shown that the thymus derived class I or class II restricted agonist selected CD8aa+ T cells are functional when exposed to antigen in vitro or in vivo. However, in normal mice chronic inflammation of the intestine due to the presence of numerous autoreactive T cells is not observed and the TCR/antigen transgenic mice do not show signs of autoimmune disorders. Agonist selected T cells are specialized self-specific T cells with regulatory functions.

CD8aß heterodimers are the normal form of the CD8 coreceptor expressed on thymocytes and splenocytes, and in mice, CD8ß requires CD8a for surface expression. CD8a, by contrast, can be expressed on the cell surface as an aa homodimer in the absence of CD8ß. CD8aa can also be induced on mature T cells, class I or class II restricted and transiently expressed, while CD8aß expressing T cells are committed to the class I restricted TCR lineage. CD8aa is not an effective coreceptor during development or selection of conventional T cells. Unlike the classical coreceptors, CD4 and CD8aß, CD8aa expression on mature T cells is not mutual exclusive and CD8aa can be acquired after the selection of CD4+ or CD8aß+ cells in the thymus. The induction of CD8aaexpression is not confined to the IEL of mice. We have shown recently that CD8aa is induced on conventional CD8aß T cells upon activation. The induction of CD8aa on these cells is transient and disappears after the initial stimulation. Not all the activated CD8aß T cells induce CD8aa, but those effector cells that do so, have the ability to further differentiate into memory CD8 T cells. Not only is CD8aa a specific marker for memory precursor cells, but we have also shown that CD8aa when engaged with its ligand, the thymic leukemia (TL) antigen, plays a crucial role for the survival and differentiation of CD8aß memory precursor cells.

Previously we had shown that the CD8aa ligand, TL, is abundantly expressed on intestinal epithelial cells and that the interaction of CD8aa with TL profoundly modifies TCR mediated responses. TL is also transiently induced on dendritic cells (DCs) and the interaction of CD8aa by TL rescues activated conventional T cells from AICD. The interaction of this receptor/ligand pair correlates with the expression of high levels of anti-apoptotic factors, including Bcl-2 and Bcl-xl and upregulation of the survival cytokine receptor IL-7R on these effector cells. Similarly we have observed the rescue of AICD during agonist selection of CD8aa expressing immature thymocytes. We have shown that IL-15 is able of expanding immature CD8aa DN thymocytes and that IL-15 is also a growth factor for CD8aa expressing memory CD8 precursor cells as well as for the CD8aa SP IEL.

The striking similarities between conventional memory T cells and IEL suggest that all IEL might be memory T cells. Agonist selected self-specific CD8aa IEL adapt to the memory phenotype already during selection in the thymus and are therefore called "natural memory" T cells. Conventional CD4 and CD8aß TCRaß IEL adapt to the memory phenotype in the periphery upon specific antigen stimulation and are therefore called "acquired memory" T cells.

T CELL FUNCTION

We are now trying to elucidate the regulatory functions displayed by the self-specific agonist selected T cells and their role in controlling autoimmune diseases, graft rejections and tumor rejection. We are also investigating the critical role of the DCs in instructing the effector cells to differentiate along the memory differentiation pathway.

CD4+ cytotoxic Lymphocytes

MHC class-II restricted CD4+ T cytotoxic cells (CD4 CTL) are among the best examples of extreme measures the immune system can take to prepare the host to deal with challenges including infections, cancers and autoimmunity. CD4+ T cells that initially committed to the T helper (Th) lineage in the thymus, have significant plasticity and are able as mature cells in the periphery to terminate the Th gene transcription program and switch on the Runx3-controlled cytotoxic phenotype and function as protective cytotoxic T lymphocytes (CTL) similarly like their MHC class I restricted CD8 counterparts. Repeatedly stimulated mature CD4 Th cells are able to lose Th-lineage master transcription factor (ThPOK; formally cKrox or Zfp67; encoded by Zbtb7b) and thereby also terminate T helper genes transcription and de-repress the Runx3controlled cytotoxicity-gene expression program. Currently, we are elucidating the mechanisms that lead to the reprogramming of CD4 Th cells to CTL, as well as determining their roles in preventing or causing inflammatory diseases and in anti-tumor or anti-viral immunity.

Selected References

Mucida, D., M. M. Husain, S. Muroi, F. van Wijk, R. Shinnakasu, Y. Naoe, B. S. Reis, Y. Huang, F. Lambolez, M. Docherty, A. Attinger, J. W. Shui, G. Kim, C. J. Lena, S. Sakaguchi, C. Miyamoto, P. Wang, K. Atarashi, Y. Park, T. Nakayama, K. Honda, W. Ellmeier, M. Kronenberg, I. Taniuchi and H. Cheroutre (2013). "Transcriptional reprogramming of mature CD4(+) helper T cells generates distinct MHC class II-restricted cytotoxic T lymphocytes." Nat Immunol 14(3): 281-289.

Mechanisms involved in the generation of high affinity effector memory T cells

A hallmark of immune memory is that repeated infections are met with accelerated or/and enhanced protective immunity. Furthermore, unlike naive T lymphocytes or central memory T cells, which reside in lymphoid tissues, some antigen-experienced T cells gain the ability to persist long term as effector memory T cells (TEM cells) in non ¬lymphoid tissues such as the intestine. Central memory T cells, which respond with robust clonal expansion, are effective at clearing pathogens that invaded the body and replicate systemically, but they are inadequate to protect the mucosal borders against viral infections (including human immunodeficiency virus (HIV)) or intracellular bacteria that penetrate the mucosal epithelia. Effective resistance to the invasion of such pathogens requires the presence of local, pre-existing antigen-specific TEM cells before rechallenge. Therefore, strategies aimed at inducing a powerful protective immune response that also warrants the formation of preexisting mucosal antigen-specific TEM cells are considered an essential goal of successful vaccination.

Class I-restricted cytotoxic T cells, or “CD8 T cells”, express the CD8αβ heterodimer as a co-receptor for their T cell receptor (TCR) and exert potent killing capacities toward infected cells or tumor cells. While CD8β requires pairing with CD8α to be expressed at the cell surface, CD8α can be expressed as a CD8αα homodimer in the absence of CD8β.

Lab achievements:

Our group has demonstrated that upon activation, some CD8 T cells will transiently co-express CD8αα and that this induction of CD8αα is a hallmark of high affinity T cells that will differentiate into TEM cells. Activation-induced CD8αα is not just a marker of TEM precursors, but CD8αα, counteracts the CD8ab coreceptor and rescues strongly activated high affinity effector T cells from activation-induced cell death (AICD). Furthermore, by interacting with the non-classical major histocompatibility complex (MHC) class I molecule thymus leukemia antigen (TL), induced on dendritic cells and expressed constitutively on intestinal epithelial cells, CD8 also rescues activated CD8 T cells from TL-induced cell death (TICD), allowing fully differentiated high affinity TEM to selectively accumulate and persist long-term at mucosal barriers. These TEM, which abundantly reside within the epithelium of the intestine, form a crucial rapidly responding pre-existing first line of defense to prevent re-infections.

Ongoing investigations:
Since CD8αα plays a crucial role in the generation of TEM cells, we are now investigating two main questions:

1/ What are the mechanisms involved in CD8αα induction (associated with the fully functional differentiation of cytotoxic effector cells) following TCR activation?

2/ How does CD8αα mediates the selective survival of high affinity CD8 effector T cells?

Significance:
Our studies so far, suggest that both lymphoid and mucosal memory are required for protection, but that the absence of mucosal immunity leads to a significant time-lapse in the immune defense which might be one of the most significant causes of setbacks in the fierce effort to develop an effective HIV vaccine. It is evident that the need for better knowledge to understand natural memory is of utmost importance to conquer the battle against devastating infectious pathogens as well as transformed cells.

Selected References

Huang, Y., Y. Park, Y. Wang-Zhu, A. Larange, R. Arens, I. Bernardo, D. Olivares-Villagomez, D. Herndler-Brandstetter, N. Abraham, B. Grubeck-Loebenstein, S. P. Schoenberger, L. Van Kaer, M. Kronenberg, M. A. Teitell and H. Cheroutre (2011). "Mucosal memory CD8(+) T cells are selected in the periphery by an MHC class I molecule." Nat Immunol 12(11): 1086-1095.

Leishman, A. J., O. V. Naidenko, A. Attinger, F. Koning, C. J. Lena, Y. Xiong, H. C. Chang, E. Reinherz, M. Kronenberg and H. Cheroutre (2001). "T cell responses modulated through interaction between CD8alphaalpha and the nonclassical MHC class I molecule, TL." Science 294(5548): 1936-1939.

Madakamutil, L. T., U. Christen, C. J. Lena, Y. Wang-Zhu, A. Attinger, M. Sundarrajan, W. Ellmeier, M. G. von Herrath, P. Jensen, D. R. Littman and H. Cheroutre (2004). "CD8alphaalpha-mediated survival and differentiation of CD8 memory T cell precursors." Science 304(5670): 590-593.

Role of pre-TCR signaling in Central Tolerance and Autoimmunity?

Autoimmunity is a self-destructive disease condition mediated mainly by pathogenic selfreactive αβ T cell receptor (TCR) expressing T lymphocytes. Self-tolerance for T cells is initially established during thymic selection and based on the affinity/avidity of the αβTCR for self-antigen/Major Histocompatibility Complex (MHC). During this selection process, maturing thymocytes receiving a moderate signal through their TCR will be positively selected and further mature to “naïve” T cells that seed the lymphoid tissues in the periphery. Thymocytes that receive a strong “agonist” signal will either undergo activation-induced cell death or alternatively, they will further mature and exit the thymus as antigen-experienced functional mature T lymphocytes. In contrast to pathogenic auto-reactive T cells, agonist selected T cells are not auto-destructive but instead, the self-antigen-driven selection process clonally diverts them to become beneficial cell types, including FoxP3+ natural regulatory T cells (nTregs), CD4- and CD8αβ- or double negative (DN) intraepithelial T cells or invariant natural killer T (iNKT) cells. In autoimmunity, however, the presence of aberrant self-destructive T cells indicates that central tolerance is defective and that the clonal deletion and/or deviation of self-reactive T cells failed. Auto-aggressive TCRαβ T cells have variable self-antigen specificities and nTregs fail to control them in autoimmunity, suggesting a global defect in central tolerance that affects selected TCRαβ lymphocytes in general.

Before thymocytes express a full variable αβTCR that is unique for each progenitor, they express a pre-TCR consisting of the CD3 components complexed with a variable rearranged TCRβ chain together with an invariant pre-Tα chain that is shared by all maturing thymocytes. Previous work from our lab, indicated that a pre-selection process occurs at this pre-TCR stage, which influences the selection fate of the developing thymocytes well before they express a full variable αβTCR. Furthermore, our lab also found that in autoimmune-prone mouse strains, including NOD (non-obese diabetes) and SJL (highly susceptible for experimental autoimmune encephalomyelitis) mice, the pre-Tα shows unique alterations in its cytoplasmic signaling domain and that, the pre-Tα isoforms display unique expression kinetics associated with autoimmune susceptibility.

We propose that alteration of the pre-TCR signaling can lead to aberrant thymic selection and a shift in the TCR repertoire that ultimately results in impaired central tolerance and autoimmunity.

Significance:

Although it is generally accepted that autoimmune diseases originate from impaired central and peripheral tolerance and the generation of auto-aggressive TCRαβ lymphocytes, it is not understood what drives the altered selection fate of the precursors of pathogenic self-reactive T cells. We propose that alterations in the common invariant pre-T chain lay at the basis of aberrant central and peripheral tolerance and autoimmunity. Identifying the cause of autoimmunity is of significant importance, not only to enhance our understanding of autoimmunity, but more importantly, new insights gained from our study will have important translational implications allowing for early detection of autoimmunity susceptibility and thus for effective strategies to treat and even prevent autoimmunity all together.

Selected References

Gangadharan, D., F. Lambolez, A. Attinger, Y. Wang-Zhu, B. A. Sullivan and H. Cheroutre (2006). "Identification of pre- and postselection TCRalphabeta+ intraepithelial lymphocyte precursors in the thymus." Immunity 25(4): 631-641.

Mucosal CD4- CD8- T cells

One large subgroup of specialized T cells is encompassed by the intraepithelial T cells which are located in the epithelium of the small intestine in humans and mice. intraepithelial T cells are distinct from conventional T cells with regard to phenotype and function, with the great majority of the intraepithelial T cells being CD8+ cytotoxic T cells. Furthermore, in mice most of these CD8+ intraepithelial T cells exclusively express an αα homodimeric form of CD8 as opposed to the more typical CD8αβ heterodimer expressed by CD8+ splenocytes. The CD8αα+ intraepithelial T cells population characteristically contains numerous TCRgd+ T cells, CD4- CD8αβ- TCRαβ cells (also called double negative or DN TCRαβ intraepithelial T cells), and CD4+ CD8αα+ (or CD4 cytotoxic T cells) or CD8αβ+CD8αα+ intraepithelial T cells. CD8αα expression on T cells does not depend upon CD8β expression in the thymus. DN TCRαβ intraepithelial T cells do require β2m dependent MHC class I expression for their differentiation and/or homeostasis. They are, however, much less dependent on TAP expression and interestingly, these cells are present in mice that lack classical class I molecules (Kb and Db deficient mice). All mucosal T cells typically have an activated effector/memory phenotype. Furthermore intraepithelial T cells harbor numerous potentially autoreactive T cells, as evidenced by the presence of cells expressing forbidden Vβs reactive with autologous, retroviral-encoded superantigens. Conventional T cells are positively selected by weak interactions with self-peptides. By contrast, we have shown, using several transgenic systems in which a TCR transgene and an agonist for that TCR are co-expressed, that thymocytes expressing an autoreactive TCRαβ are positively selected in an a-CPM dependent way by the thymus and preferentially give rise to DN CD8αα expressing T cells in the gut. We have called this process "agonist selection" to distinguish it from conventional positive selection. In this last study, we have shown that the thymus derived class I or class II restricted agonist selected DN T cells are functional when exposed to antigen in vitro or in vivo. However, in normal mice chronic inflammation of the intestine due to the presence of numerous autoreactive T cells is not observed and the TCR/antigen transgenic mice do not show signs of autoimmune disorders. Agonist selected T cells are specialized self-specific T cells with regulatory functions.

Lab achievements:
- Agonist selection pathway:
We previously showed that high affinity (also known as agonist) interactions with thymic self-peptide-MHC complexes are key for their positive selection and functional maturation. Based on those findings we hypothetized that thymic precursors must have the ability to survive such high affinity interaction. Indeed, immature TP (DP thymocytes expressing CD8αα homodimer) but not DP thymocytes, are able to survive and differentiate to DN antigen-experienced cells in vitro whereas DP thymocytes die. This suggests that in vivo TP thymocytes might be the direct pre-selected precursors that transition to mature DN TCR thymocytes in response to agonist selection signals. Therefore, agonist selection promotes maturation of DN TCR+ T cells that exit the thymus as antigen-experienced T cells and have the capacity to migrate directly to peripheral tissues including the epithelium of the intestine (see figure). Finally, we recently developed a novel mouse model where mice are engineered to express TCRs isolated from naturally arising DN TCR+ intraepithelial T cells in the presence of natural endogenous self-antigens. The analysis of those mice showed that mature DN T cells are present in both in the spleen and the epithelium of the intestine, suggesting that the nature of the TCR and cognate self antigens imprints the commitment to the DN T cell lineage.

-MHC restriction:

Using multiple TCRs cloned from naturally arising DN T cells we showed that the MHC restriction of DN TCR+ intraepithelial T cells is variable. Indeed, some clones were restricted to classical MHC Ia (H2-K or H2-D), whereas other clones recognized non-classical 2m-dependent MHC Ib molecules. In addition, H2-K or -D restricted clones were TAP-independent whereas those recognizing MHC Ib molecules were either TAP-dependent or independent. Thus, the MHC restriction of DN TCR+ intraepithelial T cells is highly variable, a characteristic that distinguishes them from mainstream conventional selected CD8+ or CD4+ T cells and from other non-conventional T cell lineages such as iNKT or MAIT cells. This unusual MHC restriction pattern not only indicates that this is a unique T cell population but more importantly it suggests that these cells recognize antigens that cannot be sensed by other T cell subsets.

Significance:

In general our studies have led to a revision of the paradigm of thymic selection, requiring the addition of agonist selection along the conventional selection pathway as a mechanism to educate and select diverse subpopulations of specialized T cells. In addition, we recently showed that DN TCR+ T cells represent a non-redundant T cell population which have the ability to recognize a myriad of antigens presented by various MHC molecules and generated by different antigen presentation pathways that fail to engage conventional CD4 and CD8 T cells or any other T cell subset.

Selected References

Gapin, L., H. Cheroutre and M. Kronenberg (1999). "Cutting edge: TCR alpha beta+ CD8 alpha alpha+ T cells are found in intestinal intraepithelial lymphocytes of mice that lack classical MHC class I molecules." J Immunol 163(8): 4100-4104.

Leishman, A. J., L. Gapin, M. Capone, E. Palmer, H. R. MacDonald, M. Kronenberg and H. Cheroutre (2002). "Precursors of functional MHC class I- or class II-restricted CD8alphaalpha(+) T cells are positively selected in the thymus by agonist self-peptides." Immunity 16(3): 355-364.

Gangadharan, D., F. Lambolez, A. Attinger, Y. Wang-Zhu, B. A. Sullivan and H. Cheroutre (2006). "Identification of pre- and postselection TCRalphabeta+ intraepithelial lymphocyte precursors in the thymus." Immunity 25(4): 631-641.

Leishman, A. J., L. Gapin, M. Capone, E. Palmer, H. R. MacDonald, M. Kronenberg and H. Cheroutre (2002). "Precursors of functional MHC class I- or class II-restricted CD8alphaalpha(+) T cells are positively selected in the thymus by agonist self-peptides." Immunity 16(3): 355-364.

Mayans, S., D. Stepniak, S. F. Palida, A. Larange, J. Dreux, B. M. Arlian, R. Shinnakasu, M. Kronenberg, H. Cheroutre and F. Lambolez (2014). "alphabetaT cell receptors expressed by CD4(-)CD8alphabeta(-) intraepithelial T cells drive their fate into a unique lineage with unusual MHC reactivities." Immunity 41(2): 207-218.

The contribution of central and/or peripheral tolerance in Celiac Disease.

Celiac Disease (CD) is an autoimmune-like inflammatory disease induced by aberrant immune responses initiated by MHC class II restricted CD4 T cells and directed towards dietary gluten. CD is the prototype of diseases in which a clear role of antigen-specific T cells has been demonstrated and where their inhibition - gluten free diet - results in disease amelioration. However, the underlying cause of this immune intolerance is not understood and all attempts so far to design a mouse model for CD have failed. Humanized mice that are transgenic for celiac associated MHC class II (HLA DQ2/8), a gluten peptide specific TCR isolated from human CD4 T cells and human CD4 do not develop celiac disease upon consuming a gluten containing diet. A possible explanation could be because the thymocytes expressing the human T cell derived TCR are selected and educated in a mouse thymic environment.

The thymus is important for the induction of central tolerance. Clonal deletion (negative selection) or functional differentiation (agonist selection) of self-reactive T cells during central tolerance in the thymus is thought to remove or divert self-specific T lymphocytes away from the naive pool of T cells in the periphery, thus reducing the threat of autoimmunity. Nevertheless, mature T cells with cross-reactivity for endogenous peptides remain present in both, humans and mice. Most of these auto reactive cells are specialized lymphocyte subsets such as the natural T regulatory cells (Tregs), the invariant natural killer cells (iNKT) and the double negatve (DN) variable T cells that do not express a CD4 or CD8ß TCR coreceptor and display variable MHC restriction.

Lab achievements:

Our group identified an ‘alternative' self-antigen-based thymic maturation process (agonist selection) resulting in the functional differentiation of mature DN TCRß-expressing T cells that directly migrate to the intestinal epithelium as self-reactive T cells with a cytotoxic functional phenotype.

Ongoing investigations:

Autoimmunity might be the result of mature self-reactive T cells that escape negative selection or fail agonist selection and become pathogenic when reacting or cross-reacting with cognate self or harmless non-self Ags, such as diet-derived antigens, in the absence of regulation. We compare the thymic selection and peripheral T cell subsets of two TCR transgenic mouse strains, both with reactivity for the same non-self antigen but with different MHC specificity. Different thymic selection between the two strains, results in different peripheral T cell subsets. Moreover, some of the developing T cells with high affinity for a self-Ag during thymic selection escape central tolerance, and appear as naive-like conventional selected T cells in the periphery. These self-specific naive-like T cells are kept in check in the presence of their self-antigen selected regulatory counterparts, but they cause severe immune pathology in the small intestine, similar to that seen in Celiac Disease, in the absence of central or peripheral tolerance.

Regulation of mucosal immunity by stromal cells and dendritic cells crosstalk in the gut

Genetic regulation by vitamin A is involved in multiple biological processes such as embryonic development, vision, and immunity. To exert this regulatory role, vitamin A is oxidized into its active form by retinol dehydrogenases followed by retinal dehydrogenases (RALDH). The product of this metabolism, retinoic acid (RA), binds to nuclear RA receptors (RARs), and together drive the transcription of target genes that contain RA responsive elements (RAREs) within their promoters. RA is especially critical for the regulation of immune responses within the digestive tract, thereby controlling functional T-cell differentiation and directing lymphocyte migration toward the intestine. Accordingly, dendritic cells (DCs) in the lamina propria (LP), Peyer’s patches, and mesenteric lymph nodes (MLNs), but not spleen- or peripheral lymph nodes, express RALDH and produce RA. However, little is known about how migratory DCs acquire RALDH activity, and the relevance of different factors such as cytokines or the presence of commensals.

Lab achievements:

We identified a stromal cell (SC) population capable of imprinting DCs with RALDH activity. These SCs are an abundant component of the intestinal LP and might represent a direct source of RA. Importantly, we show that these SCs are in close contact with CD103-expressing DCs and that this interaction conversely promotes granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion by the SCs, which in addition to RA, is absolutely required for effective RALDH induction in the DC compartment. Finally, we also found that, unlike DCs, the constitutive RALDH expression by LP SCs is independent of RA, whereas it did require the presence of the microbiota. Our findings therefore identified an RA-producing LP SC as a direct sensor of the gut environment and an important regulator of the functional maturation of mucosal DCs. The results also demonstrate an unexpected two-way cross-talk between these SCs and the DCs that might have an important role in controlling the tolerogenic or inflammatory nature of the mucosal immune response.

Significance:

The SCs we have identified might be key factors in directing and controlling the immune response at the mucosal forefront. The fact that the SCs depend on the presence of the microflora for their educational role, further suggests that they are important sentinels that have the capacity to report on the condition of the intestinal lumen and accordingly regulate the tolerogenic or inflammatory nature of the immune response.

Selected References

Vicente-Suarez, I., A. Larange, C. Reardon, M. Matho, S. Feau, G. Chodaczek, Y. Park, Y. Obata, R. Gold, Y. Wang-Zhu, C. Lena, D. M. Zajonc, S. P. Schoenberger, M. Kronenberg and H. Cheroutre (2015). "Unique lamina propria stromal cells imprint the functional phenotype of mucosal dendritic cells." Mucosal Immunol 8(1): 141-151.