Inducible costimulator controls migration of T cells to the lungs via down-regulation of CCR7 and CD62L

Metabolic priming of GD2 TRAC-CAR T cells during manufacturing promotes memory phenotypes while enhancing persistence

Manufacturing chimeric antigen receptor (CAR) T cell therapies is complex, with limited understanding of how medium composition impacts T cell phenotypes. CRISPR-Cas9 ribonucleoproteins can precisely insert a CAR sequence while disrupting the endogenous T cell receptor alpha constant (TRAC) gene resulting in TRAC-CAR T cells with an enriched stem cell memory T cell population, a process that could be further optimized through modifications to the medium composition. In this study we generated anti-GD2 TRAC-CAR T cells using "metabolic priming" (MP), where the cells were activated in glucose/glutamine-low medium and then expanded in glucose/glutamine-high medium. T cell products were evaluated using spectral flow cytometry, metabolic assays, cytokine production, cytotoxicity assays in vitro, and potency against human GD2+ xenograft neuroblastoma models in vivo. Compared with standard TRAC-CAR T cells, MP TRAC-CAR T cells showed less glycolysis, higher CCR7/CD62L expression, more bound NAD(P)H activity, and reduced IFN-γ, IL-2, IP-10, IL-1β, IL-17, and TGF-β production at the end of manufacturing ex vivo, with increased central memory CAR T cells and better persistence observed in vivo. MP with medium during CAR T cell biomanufacturing can minimize glycolysis and enrich memory phenotypes ex vivo, which could lead to better responses against solid tumors in vivo.

Metabolic priming of GD2 TRAC -CAR T cells during manufacturing promotes memory phenotypes while enhancing persistence

Manufacturing Chimeric Antigen Receptor (CAR) T cell therapies is complex, with limited understanding of how media composition impact T-cell phenotypes. CRISPR/Cas9 ribonucleoproteins can precisely insert a CAR sequence while disrupting the endogenous T cell receptor alpha constant ( TRAC ) gene resulting in TRAC -CAR T cells with an enriched stem cell memory T-cell population, a process that could be further optimized through modifications to the media composition. In this study we generated anti-GD2 TRAC -CAR T cells using "metabolic priming" (MP), where the cells were activated in glucose/glutamine low media and then expanded in glucose/glutamine high media. T cell products were evaluated using spectral flow cytometry, metabolic assays, cytokine production, cytotoxicity assays in vitro and potency against human GD2+ xenograft neuroblastoma models in vivo . Compared to standard TRAC -CAR T cells, MP TRAC -CAR T cells showed less glycolysis, higher CCR7/CD62L expression, more bound NAD(P)H activity and reduced IFN-γ, IL-2, IP-10, IL-1β, IL-17, and TGFβ production at the end of manufacturing ex vivo , with increased central memory CAR T cells and better persistence observed in vivo . Metabolic priming with media during CAR T cell biomanufacturing can minimize glycolysis and enrich memory phenotypes ex vivo , which could lead to better responses against solid tumors in vivo .

Treg cell: Critical role of regulatory T-cells in depression

Depression is a highly prevalent disorder of the central nervous system. The neuropsychiatric symptoms of clinical depression are persistent and include fatigue, anorexia, weight loss, altered sleep patterns, hyperalgesia, melancholia, anxiety, and impaired social behaviours. Mounting evidences suggest that neuroinflammation triggers dysregulated cellular immunity and increases susceptibility to psychiatric diseases. Neuroimmune responses have transformed the clinical approach to depression because of their roles in its pathophysiology and their therapeutic potential. In particular, activated regulatory T (Treg) cells play an increasingly evident role in the inflammatory immune response. In this review, we summarized the available data and discussed in depth the fundamental roles of Tregs in the pathogenesis of depression, as well as the clinical therapeutic potential of Tregs. We aimed to provide recent information regarding the potential of Tregs as immune-modulating biologics for the treatment and prevention of long-term neuropsychiatric symptoms of depression.

Inducible Costimulator-C-X-C Motif Chemokine Receptor 3 Signaling is Involved in Chronic Obstructive Pulmonary Disease Pathogenesis

Background

The role of inducible costimulator (ICOS) signaling in chronic obstructive pulmonary disease (COPD) has not been fully elucidated.

Methods

We compared the percentages of ICOS⁺ T cells and ICOS⁺ regulatory T (Treg) cells in CD4⁺ T cells and CD4⁺CD25⁺FOXP3⁺ Tregs, respectively, in the peripheral blood of smokers with or without COPD to those in healthy controls. We further characterized their phenotypes using flow cytometry. To investigate the influence of ICOS signaling on C-X-C motif chemokine receptor 3 (CXCR3) expression in COPD, we evaluated the expression levels of ICOS and CXCR3 in vivo and in vitro.

Results

ICOS expression was elevated on peripheral CD4⁺ T cells and CD4⁺ Tregs of COPD patients, which positively correlated with the severity of lung function impairment in patients with stable COPD (SCOPD), but not in patients with acute exacerbation of COPD (AECOPD). ICOS⁺CD4⁺ Tregs in patients with SCOPD expressed higher levels of coinhibitors, programmed cell death protein 1 (PD-1) and T-cell immunoreceptor with Ig and ITIM domains (TIGIT), than ICOS⁻CD4⁺ Tregs, whereas ICOS⁺CD4⁺ T cells mostly exhibited a central memory (CD45RA⁻CCR7⁺) or effector memory (CD45RA⁻CCR7⁻) phenotype, ensuring their superior potential to respond potently and quickly to pathogen invasion. Furthermore, increased percentages of CXCR3⁺CD4⁺ T cells and CXCR3⁺CD4⁺ Tregs were observed in the peripheral blood of patients with SCOPD, and the expression level of CXCR3 was higher in ICOS⁺CD4⁺ T cells than in ICOS⁻CD4⁺ T cells. The percentage of CXCR3⁺CD4⁺ T cells was even higher in the bronchoalveolar lavage fluid than in matched peripheral blood in SCOPD group. Lastly, in vitro experiments showed that ICOS induced CXCR3 expression on CD4⁺ T cells.

Conclusions

ICOS signaling is upregulated in COPD, which induces CXCR3 expression. This may contribute to increased numbers of CXCR3⁺ Th1 cells in the lungs of patients with COPD, causing inflammation and tissue damage.

Engagement of the costimulatory molecule ICOS in tissues promotes establishment of CD8+ tissue-resident memory T cells

Elevated gene expression of the costimulatory receptor Icos is a hallmark of CD8⁺ tissue-resident memory (Trm) T cells. Here, we examined the contribution of ICOS in Trm cell differentiation. Upon transfer into WT mice, Icos^-/- CD8⁺ T cells exhibited defective Trm generation but produced recirculating memory populations normally. ICOS deficiency or ICOS-L blockade compromised establishment of CD8⁺ Trm cells but not their maintenance. ICOS ligation during CD8⁺ T cell priming did not determine Trm induction; rather, effector CD8⁺ T cells showed reduced Trm differentiation after seeding into Icosl^-/- mice. Icos^YF/YF CD8⁺ T cells were compromised in Trm generation, indicating a critical role for PI3K signaling. Modest transcriptional changes in the few Icos^-/- Trm cells suggest that ICOS-PI3K signaling primarily enhances the efficiency of CD8⁺ T cell tissue residency. Thus, local ICOS signaling promotes production of Trm cells, providing insight into the contribution of costimulatory signals in the generation of tissue-resident populations.

ICOS+ Tregs: A Functional Subset of Tregs in Immune Diseases

Recent studies have reported the pathological effect of ICOS⁺ T cells, but ICOS signals also widely participate in anti-inflammatory responses, particularly ICOS⁺ regulatory T (Treg) cells. The ICOS signaling pathway endows Tregs with increased generation, proliferation, and survival abilities. Furthermore, there is enough evidence to suggest a superior capacity of ICOS⁺ Tregs, which is partly attributable to IL-10 induced by ICOS, yet the associated mechanism needs further investigation. In this review, we discuss the complicated role of ICOS⁺ Tregs in several classical autoimmune diseases, allergic diseases, and cancers and investigate the related therapeutic applications in these diseases. Moreover, we identify ICOS as a potential biomarker for disease treatment and prognostic prediction. In addition, we believe that anti-ICOS/ICOSL monoclonal antibodies exhibit excellent clinical application potential. A thorough understanding of the effect of ICOS⁺ Tregs and the holistic role of ICOS toward the immune system will help to improve the therapeutic schedule of diseases.

ICOS Costimulation Differentially Affects T Cells in Secondary Lymphoid Organs and Inflamed Tissues

B-cell interaction with follicular helper T cells and subsequent differentiation of B cells into high-affinity APCs normally takes place in secondary lymphoid organs. The costimulator ICOS plays a key role in this process and is therefore considered as an attractive target to modulate exaggerated B-cell responses in autoimmune or allergic diseases. Inflamed tissues were recently recognized as additional sites of active T-cell/B-cell interaction. To analyze whether ICOS costimulation is also important there, we employed a mouse airway inflammation model that allows direct comparison of immune reactions in the lung-draining lymph node and the lung tissue as well as assessment of the relative importance of dendritic cells versus B cells as APCs. In both organs, ICOS regulated the pool size of antigen-specific T and B cells and B-cell differentiation into germinal center(-like) cells but not into antibody-secreting cells. In the lymph node, lack of ICOS costimulation drastically reduced the frequency of T follicular helper cells but did not affect production of T-helper cell type 2 (Th2) cytokines. Vice versa in the lung tissue, ICOS did not change PD-1 expression on infiltrating T cells but regulated Th2 cytokine production, a process for which ICOS ligand expression on B cells was of particular importance. Taken together, the results of this study show that ICOS differentially regulates effector T cells in secondary lymphoid organs and inflamed tissues but that blockade of the ICOS pathway is suitable to target T cell-dependent B cell responses at both sites.

ICOS protects against mortality from acute lung injury through activation of IL-5+ ILC2s

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease causing irreversible lung scarring and loss of pulmonary function. IPF Patients suffer from a high rate of pulmonary infections and acute exacerbations of disease that further contribute to pulmonary decline. Low expression of the inducible T-cell costimulatory molecule (ICOS) in peripheral blood mononuclear cells predicts decreased survival of IPF patients, but the mechanisms by which ICOS protects are unclear. Using a model of bleomycin-induced lung injury and fibrosis, we now demonstrate that ICOS expression enhances survival from lung injury rather than regulating fibrogenesis. Of ICOS-expressing cells, type 2 innate lymphocytes (ILC2s) are the first to respond to bleomycin-induced injury, and this expansion is ICOS dependent. Interestingly, a similar decrease in ICOS⁺ ILCs was found in lung tissue from IPF patients. Interleukin (IL)-5, produced primarily by ILC2s, was significantly reduced after lung injury in ICOS^-/- mice, and strikingly, treatment with IL-5 protected both ICOS^-/- and wild-type mice from mortality. These results imply that low ICOS expression and decreased lung ILC2s in IPF patients may contribute to poor recovery from infections and acute exacerbation and that IL-5 treatment may be a novel therapeutic strategy to overcome these defects and protect against lung injury.

Down-Regulation of CD62L Shedding in T Cells by CD39+ Regulatory T Cells Leads to Defective Sensitization in Contact Hypersensitivity Reactions

Injection of regulatory T cells (Tregs) followed by sensitization with 2,4,6-trinitrochlorobenzene induced a transient increase in size and cellularity of skin-draining lymph nodes (LNs) in mice. This led us to hypothesize that Tregs may affect the trafficking of T cells from and to peripheral LNs. Two to three hours after sensitization, we found fewer CD8⁺ T cells expressing CD62L in LNs compared with untreated controls. Injection of wild-type Tregs prevented this down-regulation of CD62L. In contrast, Tregs devoid of the adenosine triphosphate (ATP)-degrading ecto-enzyme CD39 were unable to do so. As for the mechanism of CD62L regulation, we found that ATP, which is released in skin upon hapten-exposure, is inducing the protease ADAM17 in LN-residing T cells via engagement of P₂X₇ ATP receptors. ADAM17 cleaves CD62L from the surface of CD8⁺ T cells, which in turn provide a signal for T cells to leave the LNs. This regulation of CD62L is disturbed by the presence of Tregs, because Tregs remove extracellular ATP from the tissue by activity of CD39 and, therefore, abrogate the shedding of CD62L. Thus, these data indicate that the regulation of ATP turnover by Tregs in skin and LNs is an important modulator for immune responses.

Retrogenic ICOS Expression Increases Differentiation of KLRG-1hiCD127loCD8+ T Cells during Listeria Infection and Diminishes Recall Responses

Following T cell encounter with Ag, multiple signals are integrated to collectively induce distinct differentiation programs within Ag-specific CD8(+) T cell populations. Several factors contribute to these cell fate decisions, including the amount and duration of Ag, exposure to inflammatory cytokines, and degree of ligation of cosignaling molecules. The ICOS is not expressed on resting T cells but is rapidly upregulated upon encounter with Ag. However, the impact of ICOS signaling on programmed differentiation is not well understood. In this study, we therefore sought to determine the role of ICOS signaling on CD8(+) T cell programmed differentiation. Through the creation of novel ICOS retrogenic Ag-specific TCR-transgenic CD8(+) T cells, we interrogated the phenotype, functionality, and recall potential of CD8(+) T cells that receive early and sustained ICOS signaling during Ag exposure. Our results reveal that these ICOS signals critically impacted cell fate decisions of Ag-specific CD8(+) T cells, resulting in increased frequencies of KLRG-1(hi)CD127(lo) cells, altered BLIMP-1, T-bet, and eomesodermin expression, and increased cytolytic capacity as compared with empty vector controls. Interestingly, however, ICOS retrogenic CD8(+) T cells also preferentially homed to nonlymphoid organs and exhibited reduced multicytokine functionality and reduced ability to mount secondary recall responses upon challenge in vivo. In sum, our results suggest that an altered differentiation program is induced following early and sustained ICOS expression, resulting in the generation of more cytolyticly potent, terminally differentiated effectors that possess limited capacity for recall response.

Effector and central memory T helper 2 cells respond differently to peptide immunotherapy

Peptide immunotherapy (PIT) offers realistic prospects for the treatment of allergic diseases, including allergic asthma. Much is understood of the behavior of naive T cells in response to PIT. However, treatment of patients with ongoing allergic disease requires detailed understanding of the responses of allergen-experienced T cells. CD62L expression by allergen-experienced T cells corresponds to effector/effector memory (CD62L(lo)) and central memory (CD62L(hi)) subsets, which vary with allergen exposure (e.g., during, or out with, pollen season). The efficacy of PIT on different T helper 2 (Th2) cell memory populations is unknown. We developed a murine model of PIT in allergic airway inflammation (AAI) driven by adoptively transferred, traceable ovalbumin-experienced Th2 cells. PIT effectively suppressed AAI driven by unfractionated Th2 cells. Selective transfer of CD62L(hi) and CD62L(lo) Th2 cells revealed that these two populations behaved differently from one another and from previously characterized (early deletional) responses of naive CD4(+) T cells to PIT. Most notably, allergen-reactive CD62L(lo) Th2 cells were long-lived within the lung after PIT, before allergen challenge, in contrast to CD62L(hi) Th2 cells. Despite this, PIT was most potent against CD62L(lo) Th2 cells in protecting from AAI, impairing their ability to produce Th2 cytokines, whereas this capacity was heightened in PIT-treated CD62L(hi) Th2 cells. We conclude that Th2 cells do not undergo an early deletional form of tolerance after PIT. Moreover, memory Th2 subsets respond differently to PIT. These findings have implications for the clinical translation of PIT in different allergic scenarios.

ICOS regulates the generation and function of human CD4+ Treg in a CTLA-4 dependent manner

Inducible co-stimulator (ICOS) is a member of CD28/Cytotoxic T-lymphocyte Antigen-4 (CTLA-4) family and broadly expressed in activated CD4(+) T cells and induced regulatory CD4(+) T cells (CD4(+) iTreg). ICOS-related signal pathway could be activated by the interaction between ICOS and its ligand (ICOSL). In our previous work, we established a cost-effective system to generate a novel human allo-antigen specific CD4(hi) Treg by co-culturing their naïve precursors with allogeneic CD40-activated B cells in vitro. Here we investigate the role of ICOS in the generation and function of CD4(hi) Treg by interrupting ICOS-ICOSL interaction with ICOS-Ig. It is found that blockade of ICOS-ICOSL interaction impairs the induction and expansion of CD4(hi) Treg induced by allogeneic CD40-activated B cells. More importantly, CD4(hi) Treg induced with the addition of ICOS-Ig exhibits decreased suppressive capacity on alloantigen-specific responses. Dysfunction of CD4(hi) Treg induced with ICOS-Ig is accompanied with its decreased exocytosis and surface CTLA-4 expression. Through inhibiting endocytosis with E64 and pepstatin A, surface CTLA-4 expression and suppressive functions of induced CD4(hi) Treg could be partly reversed. Conclusively, our results demonstrate the beneficial role of ICOS-ICOSL signal pathway in the generation and function of CD4(hi) Treg and uncover a novel relationship between ICOS and CTLA-4.

Location, location, location: the impact of migratory heterogeneity on T cell function

T cell migration is crucial for an effective adaptive immune response to invading pathogens. Naive and memory T cells encounter pathogen antigens, become activated, and differentiate into effector cells in secondary lymphoid tissues, and then migrate to the site(s) of infection where they exert effector activities that control and eliminate pathogens. To achieve activation, efficient effector function, and good memory formation, T cells must traffic between lymphoid and non-lymphoid tissues within the body. This complex process is facilitated by chemokine receptors, selectins, CD44, and integrins that mediate the interactions of T cells with the environment. The expression patterns of these migration receptors (MR) dictate the tissues into which the effector T cells migrate and enable them to occupy specific niches within the tissue. While MR have been considered primarily to facilitate cell movement, we highlight how the heterogeneity of signaling through these receptors influences the function and fate of T cells in situ. We explore what drives MR expression heterogeneity, how this affects migration, and how this impacts T cell effector function and memory formation.

ICOS-expressing lymphocytes promote resolution of CD8-mediated lung injury in a mouse model of lung rejection

Acute rejection, a common complication of lung transplantation, may promote obliterative bronchiolitis leading to graft failure in lung transplant recipients. During acute rejection episodes, CD8(+) T cells can contribute to lung epithelial injury but the mechanisms promoting and controlling CD8-mediated injury in the lung are not well understood. To study the mechanisms regulating CD8(+) T cell-mediated lung rejection, we used a transgenic model in which adoptively transferred ovalbumin (OVA)-specific cytotoxic T lymphocytes (CTL) induce lung injury in mice expressing an ovalbumin transgene in the small airway epithelium of the lungs (CC10-OVA mice). The lung pathology is similar to findings in humans with acute lung transplant. In the presence of an intact immune response the inflammation resolves by day 30. Using CC10-OVA.RAG(-/-) mice, we found that CD4(+) T cells and ICOS(+/+) T cells were required for protection against lethal lung injury, while neutrophil depletion was not protective. In addition, CD4(+)Foxp3 (+) ICOS(+) T cells were enriched in the lungs of animals surviving lung injury and ICOS(+/+) Tregs promoted survival in animals that received ICOS(-/-) T cells. Direct comparison of ICOS(-/-) Tregs to ICOS(+/+) Tregs found defects in vitro but no differences in the ability of ICOS(-/-) Tregs to protect from lethal lung injury. These data suggest that ICOS affects Treg development but is not necessarily required for Treg effector function.

Regulatory T cells and the control of the allergic response

The study of immune regulation and tolerance has been traditionally associated with self/nonself-discrimination. However, the finding that dominant tolerance, a model that puts in evidence the active role of regulatory T cells, can develop to nonself-antigens suggests that the imposition of tolerance can be context dependent. This paper reviews the emerging field of acquired immune tolerance to non-self antigens, with an emphasis on the different subsets of induced regulatory T cells that appear to specialize in specific functional niches. Such regulatory mechanisms are important in preventing the onset of allergic diseases in healthy individuals. In addition, it may be possible to take advantage of these immune regulatory mechanisms for the induction of tolerance in cases where pathological immune responses are generated to allergens occurring in nature, but also to other immunogens such as biological drugs developed for medical therapies.

ICOS-expressing CD4 T cells induced via TLR4 in the nasal mucosa are capable of inhibiting experimental allergic asthma

Modulation of adaptive immune responses via the innate immune pattern recognition receptors, such as the TLRs, is an emerging strategy for vaccine development. We investigated whether nasal rather than intrapulmonary application of Protollin, a mucosal adjuvant composed of TLR2 and TLR4 ligands, is sufficient to elicit protection against murine allergic lower airway disease. Wild-type, Tlr2(-/-), or Tlr4(-/-) BALB/c mice were sensitized to a birch pollen allergen extract (BPEx), then received either intranasal or intrapulmonary administrations of Protollin or Protollin admixed with BPEx, followed by consecutive daily BPEx challenges. Nasal application of Protollin or Protollin admixed with BPEx was sufficient to inhibit allergic lower airway disease with minimal collateral lung inflammation. Inhibition was dependent on TLR4 and was associated with the induction of ICOS in cells of the nasal mucosa and on both CD4+Foxp3+ and CD4+Foxp3- T cells of the draining lymph nodes (LNs), as well as their recruitment to the lungs. Adoptive transfer of cervical LN CD4+ICOS+, but not CD4+ICOS-, cells inhibited BPEx-induced airway hyperresponsiveness and bronchoalveolar lavage eosinophilia. Thus, our data indicate that expansion of resident ICOS-expressing CD4+ T cells of the cervical LNs by nasal mucosal TLR4 stimulation may inhibit the development of allergic lower airway disease in mice.

Increased production of circulating soluble co-stimulatory molecules CTLA-4, CD28 and CD80 in patients with rheumatoid arthritis

Co-stimulatory molecules are key immunoregulatory mediators in regulating T lymphocyte-mediated immune responses and inflammatory reactions. Here we investigated whether there is altered expression and the clinical significance of circulating soluble co-stimulatory molecules in rheumatoid arthritis (RA) patients. Serum concentrations of sCTLA-4, sCD28, sCD80 and sCD86 in 56 RA patients, and 32 sex- and age-matched control subjects were measured by enzyme-linked immunosorbent assay (ELISA). Results showed that serum sCTLA-4, sCD28, and CD80 but not CD86 concentrations in all RA patients were significantly higher than concentrations in healthy control subjects. And there was significant and positive correlation between serum CTLA-4 and sCD28, sCD28 and sCD80, or sCTLA-4 and sCD80 in all RA patients. Serum sCTLA-4 concentration in all RA patients correlated significantly with disease activity score in 28 joints (DAS28). Moreover, immunosuppressant treatment with leflunomide could downregulate the increased levels of sCTLA-4, sCD28, and CD80 in RA patients. Therefore, the elevated production of circulating soluble T-cell co-stimulatory molecules should contribute to the pathogenesis of RA, and serum sCTLA-4 could potentially serve as a new marker of RA disease activity.