Concurrent OX40 and CD30 Ligand Blockade Abrogates the CD4-Driven Autoimmunity Associated with CTLA4 and PD1 Blockade while Preserving Excellent Anti-CD8 Tumor Immunity.

Although strategies that block FOXP3-dependent regulatory T cell function (CTLA4 blockade) and the inhibitory receptor PD1 have shown great promise in promoting antitumor immune responses in humans, their widespread implementation for cancer immunotherapy has been hampered by significant off-target autoimmune side effects that can be lethal. Our work has shown that absence of OX40 and CD30 costimulatory signals prevents CD4 T cell-driven autoimmunity in Foxp3-deficient mice, suggesting a novel way to block these side effects. In this study, we show that excellent antitumor CD8 T cell responses can be achieved in Foxp3 mice deficient in OX40 and CD30 signals, particularly in the presence of concurrent PD1 blockade.

T Cell Receptor and Cytokine Signaling Can Function at Different Stages to Establish and Maintain Transcriptional Memory and Enable T Helper Cell Differentiation.

Experienced T cells exhibit immunological memory a rapid recall response, responding to restimulation much faster than naïve T cells. The formation of immunological memory starts during an initial slow response, when naïve T cells become transformed to proliferating T blast cells, and inducible immune response genes are reprogrammed as active chromatin domains. We demonstrated that these active domains are supported by thousands of priming elements which cooperate with inducible transcriptional enhancers to enable efficient responses to stimuli.

OX40, OX40L and Autoimmunity: a Comprehensive Review.

The tumour necrosis factor receptor OX40 (CD134) is activated by its cognate ligand OX40L (CD134L, CD252) and functions as a T cell co-stimulatory molecule. OX40-OX40L interactions have been proposed as a potential therapeutic target for treating autoimmunity. OX40 is expressed on activated T cells, and in the mouse at rest on regulatory T cells (Treg).

Differential requirement for CCR4 and CCR7 during the development of innate and adaptive αβT cells in the adult thymus.

αβT cell development depends upon serial migration of thymocyte precursors through cortical and medullary microenvironments, enabling specialized stromal cells to provide important signals at specific stages of their development. Although conventional αβT cells are subject to clonal deletion in the medulla, entry into the thymus medulla also fosters αβT cell differentiation. For example, during postnatal periods, the medulla is involved in the intrathymic generation of multiple αβT cell lineages, notably the induction of Foxp3(+) regulatory T cell development and the completion of invariant NKT cell development.

Evolving strategies for cancer and autoimmunity: back to the future.

Although current thinking has focused on genetic variation between individuals and environmental influences as underpinning susceptibility to both autoimmunity and cancer, an alternative view is that human susceptibility to these diseases is a consequence of the way the immune system evolved. It is important to remember that the immunological genes that we inherit and the systems that they control were shaped by the drive for reproductive success rather than for individual survival. It is our view that human susceptibility to autoimmunity and cancer is the evolutionarily acceptable side effect of the immune adaptations that evolved in early placental mammals to accommodate a fundamental change in reproductive strategy.

The chronicity of tonsillitis is significantly correlated with an increase in an LTi cell portion.

The current study explored the relationship between lymphoid tissue inducer (LTi) cells and patients' clinical and immunological status. LTi cells are critical for lymphoid tissue development and maintenance of CD4 T cell-dependent immune responses. The percentage of CD117+CD3-CD56-CD127+ RORγ+ LTi cells isolated from human tonsils was determined and correlated with changes in other immune subsets and clinical factors.

Mechanisms of thymus medulla development and function.

The development of CD4(+) helper and CD8(+) cytotoxic T-cells expressing the αβ form of the T-cell receptor (αβTCR) takes place in the thymus, a primary lymphoid organ containing distinct cortical and medullary microenvironments. While the cortex represents a site of early T-cell precursor development, and the positive selection of CD4(+)8(+) thymocytes, the thymic medulla plays a key role in tolerance induction, ensuring that thymic emigrants are purged of autoreactive αβTCR specificities. In recent years, advances have been made in understanding the development and function of thymic medullary epithelial cells, most notably the subset defined by expression of the Autoimmune Regulator (Aire) gene.

The thymic medulla is required for Foxp3+ regulatory but not conventional CD4+ thymocyte development.

A key role of the thymic medulla is to negatively select autoreactive CD4(+) and CD8(+) thymocytes, a process important for T cell tolerance induction. However, the involvement of the thymic medulla in other aspects of αβ T cell development, including the generation of Foxp3(+) natural regulatory T cells (nTreg cells) and the continued maturation of positively selected conventional αβ T cells, is unclear. We show that newly generated conventional CD69(+)Qa2(-) CD4 single-positive thymocytes mature to the late CD69(-)Qa2(+) stage in the absence of RelB-dependent medullary thymic epithelial cells (mTECs).

Generation of both cortical and Aire(+) medullary thymic epithelial compartments from CD205(+) progenitors.

In the adult thymus, the development of self-tolerant thymocytes requires interactions with thymic epithelial cells (TECs). Although both cortical and medullary TECs (cTECs/mTECs) are known to arise from common bipotent TEC progenitors, the phenotype of these progenitors and the timing of the emergence of these distinct lineages remain unclear. Here, we have investigated the phenotype and developmental properties of bipotent TEC progenitors during cTEC/mTEC lineage development.

Developmentally regulated availability of RANKL and CD40 ligand reveals distinct mechanisms of fetal and adult cross-talk in the thymus medulla.

T cell tolerance in the thymus is a key step in shaping the developing T cell repertoire. Thymic medullary epithelial cells play multiple roles in this process, including negative selection of autoreactive thymocytes, influencing thymic dendritic cell positioning, and the generation of Foxp3(+) regulatory T cells. Previous studies show that medullary thymic epithelial cell (mTEC) development involves hemopoietic cross-talk, and numerous TNFR superfamily members have been implicated in this process.

Cutting edge: lymphoid tissue inducer cells maintain memory CD4 T cells within secondary lymphoid tissue.

Phylogeny shows that CD4 T cell memory and lymph nodes coevolved in placental mammals. In ontogeny, retinoic acid orphan receptor (ROR)γ-dependent lymphoid tissue inducer (LTi) cells program the development of mammalian lymph nodes. In this study, we show that although primary CD4 T cell expansion is normal in RORγ-deficient mice, the persistence of memory CD4 T cells is RORγ-dependent.

Lymphoid tissue inducer cells: pivotal cells in the evolution of CD4 immunity and tolerance?

PHYLOGENY SUGGESTS THAT THE EVOLUTION OF PLACENTATION IN MAMMALS WAS ACCOMPANIED BY SUBSTANTIAL CHANGES IN THE MAMMALIAN IMMUNE SYSTEM: in particular lymph nodes and CD4 high affinity memory antibody responses co-evolved during the same period. Lymphoid tissue inducer cells (LTi) are members of an emerging family of innate lymphoid cells (ILCs) that are crucial for lymph node development, but our studies have indicated that they also play a pivotal role in the long-term maintenance of memory CD4 T cells in adult mammals through their expression of the tumor necrosis family members, OX40- and CD30-ligands. Additionally, our studies have shown that these two molecules are also key operators in CD4 effector function, as their absence obviates the need for the FoxP3 dependent regulatory T (T(regs)) cells that prevent CD4 driven autoimmune responses.

Rank signaling links the development of invariant γδ T cell progenitors and Aire(+) medullary epithelium.

The thymic medulla provides a specialized microenvironment for the negative selection of T cells, with the presence of autoimmune regulator (Aire)-expressing medullary thymic epithelial cells (mTECs) during the embryonic-neonatal period being both necessary and sufficient to establish long-lasting tolerance. Here we showed that emergence of the first cohorts of Aire(+) mTECs at this key developmental stage, prior to αβ T cell repertoire selection, was jointly directed by Rankl(+) lymphoid tissue inducer cells and invariant Vγ5(+) dendritic epidermal T cell (DETC) progenitors that are the first thymocytes to express the products of gene rearrangement. In turn, generation of Aire(+) mTECs then fostered Skint-1-dependent, but Aire-independent, DETC progenitor maturation and the emergence of an invariant DETC repertoire.

Lymphoid tissue inducer cells: innate cells critical for CD4+ T cell memory responses?

Lymphoid tissue inducer cells (LTi) are a relatively new arrival on the immunological cellular landscape, having first been characterized properly only 15 years ago. They are members of an emerging family of innate lymphoid cells (ILCs). Elucidation of their function reveals links not only with the ancient innate immune system, but also with adaptive immune responses, in particular the development of lymph nodes and CD4(+) T cell memory immune responses, which on one hand underpin the success of vaccination strategies, and on the other hand drive many human immunologically mediated diseases.

OX40 and CD30 signals in CD4(+) T-cell effector and memory function: a distinct role for lymphoid tissue inducer cells in maintaining CD4(+) T-cell memory but not effector function.

CD4(+) effector and memory T cells play a pivotal role in the development of both normal and pathogenic immune responses. This review focuses on the molecular and cellular mechanisms that regulate their development, with particular focus on the tumor necrosis factor superfamily members OX40 (TNFRSF4) and CD30 (TNFRSF8). We discuss the evidence that in mice, these molecular signaling pathways act synergistically to regulate the development of both effector and memory CD4(+) T cells but that the cells that regulate memory versus effector function are distinct, effectively allowing the independent regulation of the memory and effector CD4(+) T-cell pools.

Abrogation of CD30 and OX40 signals prevents autoimmune disease in FoxP3-deficient mice.

Our previous studies have implicated signaling through the tumor necrosis family receptors OX40 and CD30 as critical for maintaining CD4 memory responses. We show that signals through both molecules are also required for CD4 effector-mediated autoimmune tissue damage. Under normal circumstances, male mice deficient in the forkhead transcription factor FoxP3, which lack regulatory CD4 T cells, develop lethal autoimmune disease in the first few weeks of life.

Clonal analysis reveals uniformity in the molecular profile and lineage potential of CCR9(+) and CCR9(-) thymus-settling progenitors.

The entry of T cell progenitors to the thymus marks the beginning of a multistage developmental process that culminates in the generation of self-MHC-restricted CD4(+) and CD8(+) T cells. Although multiple factors including the chemokine receptors CCR7 and CCR9 are now defined as important mediators of progenitor recruitment and colonization in both the fetal and adult thymi, the heterogeneity of thymus-colonizing cells that contribute to development of the T cell pool is complex and poorly understood. In this study, in conjunction with lineage potential assays, we perform phenotypic and genetic analyses on thymus-settling progenitors (TSP) isolated from the embryonic mouse thymus anlagen and surrounding perithymic mesenchyme, including simultaneous gene expression analysis of 14 hemopoietic regulators using single-cell multiplex RT-PCR.

Lymphotoxin signals from positively selected thymocytes regulate the terminal differentiation of medullary thymic epithelial cells.

The thymic medulla represents a key site for the induction of T cell tolerance. In particular, autoimmune regulator (Aire)-expressing medullary thymic epithelial cells (mTECs) provide a spectrum of tissue-restricted Ags that, through both direct presentation and cross-presentation by dendritic cells, purge the developing T cell repertoire of autoimmune specificities. Despite this role, the mechanisms of Aire(+) mTEC development remain unclear, particularly those stages that occur post-Aire expression and represent mTEC terminal differentiation.

Lymphoid tissue inducer cells and the evolution of CD4 dependent high-affinity antibody responses.

Phylogeny indicates that in mammals memory CD4-dependent antibody responses evolved after monotremes split from the common ancestor of marsupial and eutherian mammals. This was strongly associated with the development of segregated B and T cell areas and the development of a linked lymph node network. The evolution of the lymphotoxin beta receptor in these higher mammals was key to the development of these new functions.

IL-4 directs both CD4 and CD8 T cells to produce Th2 cytokines in vitro, but only CD4 T cells produce these cytokines in response to alum-precipitated protein in vivo.

While IL-4 directs CD4 T cells to produce Th2 cytokines (including IL-4, IL-13, IL-5) in vitro it has been shown that production of these cytokines can be induced in vivo in the absence of IL-4/IL-13/STAT-6 signaling. The present report shows that CD8 as well as CD4 T cells activated through their TCR, in vitro upregulate the Th2-features - IL-4, IL-13, IL-5, and GATA-3. However, in vivo while alum-precipitated antigen strongly and selectively induces these Th2-features in CD4 T cells, CD8 T cells mount a markedly different response to this antigen.

Splenic stromal cells mediate IL-7 independent adult lymphoid tissue inducer cell survival.

Lymphoid tissue inducer cells (LTi) play an important role in the development of lymphoid tissue in embryos. Adult CD4(+)CD3(-) LTi-like cells present a similar phenotype and gene expression to their embryonic counterpart and have important roles in CD4(+) T-cell memory and lymphoid tissue recovery following viral infection. However, adult LTi-like cells are heterogeneous populations and the factors that regulate their survival and accumulation within secondary lymphoid organs remain unclear, in particular whether the T-zone stroma is involved.

The survival of memory CD4+ T cells within the gut lamina propria requires OX40 and CD30 signals.

Although CD4(+) memory T cells reside within secondary lymphoid tissue, the major reservoir of these cells is in the lamina propria of the intestine. In this study, we demonstrate that, in the absence of signals through both OX40 and CD30, CD4(+) T cells are comprehensively depleted from the lamina propria. Deficiency in either CD30 or OX40 alone reduced CD4(+) T cell numbers, however, in mice deficient in both OX40 and CD30, CD4(+) T cell loss was greatly exacerbated.

NK cells protect secondary lymphoid tissue from cytomegalovirus via a CD30-dependent mechanism.

The pathogenic outcomes of viral infection are often reminiscent of a dysfunctional immune system. Thus, cytomegalovirus (CMV) causes disruption of the lymphoid architecture and the functionality of lymphocytes, both of which are features of CD30 deficiency. It was therefore plausible that CD30 might interfere with CMV infection.

Absence of thymus crosstalk in the fetus does not preclude hematopoietic induction of a functional thymus in the adult.

Cortical and medullary thymic epithelial cells provide essential signals for a normal programme of T-cell development. Current models of thymus development suggest that thymocyte-derived signals play an important role in establishing thymic microenvironments, a process termed thymus crosstalk. Studies on CD3epsilontg26 mice lacking intrathymic T-cell progenitors provided evidence that normal development of the thymic cortex depends upon thymocyte-derived signals.