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A previous paper has reported that blockade of NKG2 D was effective in protecting allograft in murine models of cardiac transplantation, but the mechanism of NKG2 D blockade on attenuated cardiac allograft vasculopathy ( CAV) was still unknown. In our current study, we found that wild-type recipients treated with anti- NKG2 D monoclonal antibody (m Ab) plus cytotoxic T lymphocyte antigen ( CTLA)-4-immunoglobulin ( I)g showed prolonged allograft survivals (>90 days, P < 0·001) significantly and attenuated CAV. These in-vivo results correlated with reduced alloantibody production, low expression of interleukin ( IL)-17 and IL-6, while infiltration of regulatory T cells increased. IL-6 administration induced shorter allograft survival and higher CAV grade in CTLA-4- Ig plus anti- NKG2 D m Ab-treated recipients, whereas IL-17 had no significant effect on allograft survival and CAV grade in CTLA-4- Ig plus anti- NKG2 D m Ab-treated recipients. Furthermore, the prolonged allograft survival induced by NKG2 D blockade was abrogated partially with depletion of regulatory T cells. In conclusion, blockade of NKG2 D combined with CTLA-4- Ig attenuated CAV and this effect was associated with lower alloantibody production, inhibited IL-6 expression and enhanced expansion of regulatory T cells. [ABSTRACT FROM AUTHOR]

Esophageal squamous cell carcinoma (ESCC), one of the most commonly diagnosed and lethal malignant diseases, has a complex tumor ecosystem. An obvious requirement for T-cell-mediated tumor control is the infiltration of tumor-reactive T cells into the tumor. Here, we obtained detailed T-cell compositions in both ESCC tumors and matched peripheral blood mononuclear cells (PBMCs) at single-cell resolution. We demonstrated that T cells in tumors and PBMCs had different compositions and functional states. ESCC tumors were rich in Treg and exhausted T cells but poor in cytotoxic and naïve T cells compared with PBMCs. The exhausted T cells showed higher exhausted signature in tumors than in PBMCs, while the cytotoxic T cells exhibited higher cytotoxic signature in PBMCs than in tumors. Our data indicated an immunosuppressive status and a defect at the level of T-cell priming in the tumor microenvironment. Leukocyte-associated Ig-like receptor-2 (LAIR2), a soluble collagen receptor that prevents the binding of human leukocyte-associated Ig-like receptor-1 (LAIR1) to collagens, was predominantly expressed in proliferating CD8+ T and Treg cells in tumors but in cytotoxic cells in PBMCs. LAIR2 could inhibit tumor metastasis, invasion, and collagen deposition via suppressing transforming growth factor-β signaling. These findings revealed differential T-cell populations in tumors and PBMCs and provided convincing evidence that LAIR2 acted as a tumor suppressor. Esophageal squamous cell carcinoma (ESCC), one of the most commonly diagnosed and lethal malignant diseases, has a complex tumor ecosystem. An obvious requirement for T-cell-mediated tumor control is the infiltration of tumor-reactive T cells into the tumor. Here, we obtained detailed T-cell compositions in both ESCC tumors and matched peripheral blood mononuclear cells (PBMCs) at single-cell resolution. We demonstrated that T cells in tumors and PBMCs had different compositions and functional states. [ABSTRACT FROM AUTHOR]

Vδ2+ T cells can recognize malignantly transformed cells as well as those infected with mycobacteria. This cross-reactivity supports the idea of using mycobacteria to manipulate Vδ2+ T cells in cancer immunotherapy. To date, therapeutic interventions using Vδ2+ T cells in cancer have involved expanding these cells in or ex vivo using zoledronic acid (ZA). Here, we show that the mycobacterium Bacillus Calmette–Guérin (BCG) also causes Vδ2+ T-cell expansion in vitro and that resulting Vδ2+ cell populations are cytotoxic toward tumour cell lines. We show that both ZA and BCG-expanded Vδ2+ cells effectively killed both Daudi and THP-1 cells. THP-1 cell killing by both ZA and BCG-expanded Vδ2+ cells was enhanced by treatment of targets cells with ZA. Although no difference in cytotoxic activity between ZA- and BCG-expanded Vδ2+ cells was observed, BCG-expanded cells degranulated more and produced a more diverse range of cytokines upon tumour cell recognition compared to ZA-expanded cells. ZA-expanded Vδ2+ cells were shown to upregulate exhaustion marker CD57 to a greater extent than BCG-expanded Vδ2+ cells. Furthermore, ZA expansion was associated with upregulation of inhibitory markers PD-1 and TIM3 in a dose-dependent manner whereas PD-1 expression was not increased following expansion using BCG. Intradermal BCG vaccination of rhesus macaques caused in vivo expansion of Vδ2+ cells. In combination with the aforementioned in vitro data, this finding suggests that BCG treatment could induce expansion of Vδ2+ T cells with enhanced anti-tumour potential compared to ZA treatment and that either ZA or BCG could be used intratumourally as a means to potentiate stronger anti-tumour Vδ2+ T-cell responses. Vd2+ gamma-delta T cells have been shown in vitroto elicit potent cytolytic responses toward tumour cells, suggesting the potential for these responses to be manipulated in cancer immunotherapy. We show that heat-killed Bacillus Calmette-Guerin (HKBCG) promotes the expansion of Vd2+ T cells both in vitroand in vivo. These HKBCG-expanded cells exhibited enhanced degranulation and cytokine production in tumour cells compared to cells expanded using bisphosphonates. [ABSTRACT FROM AUTHOR]

Epidermal melanocyte loss in vitiligo, triggered by stresses ranging from trauma to emotional stress, chemical exposure or metabolite imbalance, to the unknown, can stimulate oxidative stress in pigment cells, which secrete damage-associated molecular patterns that then initiate innate immune responses. Antigen presentation to melanocytes leads to stimulation of autoreactive T-cell responses, with further targeting of pigment cells. Studies show a pathogenic basis for cellular stress, innate immune responses and adaptive immunity in vitiligo. Improved understanding of the aetiological mechanisms in vitiligo has already resulted in successful use of the Jak inhibitors in vitiligo. In this review, we outline the current understanding of the pathological mechanisms in vitiligo and locate loci to which therapeutic attack might be directed. [ABSTRACT FROM AUTHOR]

Summary: Natural killer T (NKT) cells are an abundant subset of liver lymphocytes activated by lipid antigens presented on CD1d molecules that are expressed by cholangiocytes. We aimed to determine if bile from patients with chronic liver diseases contains antigenic lipids that can activate NKT cells. Using murine invariant (24.7, 24.8 and DN32.D3) and non‐invariant (14S.6, 14S.7 and 14S.10) NKT hybridomas we investigated the presence of lipid antigens in bile collected from the gallbladder of patients undergoing liver transplantation due to end‐stage liver disease. Biliary microbiota profiles were generated using 16S rRNA amplicon sequencing. We found that the patient bile samples contain antigens that activate both invariant and non‐invariant NKT hybridomas (24.7, 24.8, DN32.D3, 14S.6, 14S.7 and 14S.10), as demonstrated by activation of at least one hybridoma by eight of 10 bile samples. Activation at high dilutions suggests that some antigens are highly potent. We used the non‐invariant NKT hybridoma 14S.6 to screen 21 additional patient bile samples for NKT‐reactivity and demonstrated that 12 of 21 bile samples resulted in activation, three of which gave a strong activation. Four of 12 activating bile samples contained microbial DNA. Our results reveal an immunological pathway that could be of critical importance in biliary immunology. [ABSTRACT FROM AUTHOR]

Summary: Hepatic inflammatory response is a risk factor for liver cancer initiation and progression. Interleukin (IL)‐35 is the newest member of the IL‐12 cytokine family, and has been reported to play an essential role in the immunosuppressive liver microenvironment. Herein we focus on the expression profiles of IL‐35 in hepatocellular carcinoma (HCC) and effects on local immune status. HCC transcriptome array data were downloaded from Gene Expression Omnibus (GEO). Analysis was performed by BRB‐Array Tools and Ingenuity Pathway Analysis (IPA) software. Serum IL‐35 level was detected by AimPlet bead‐based immunoassay. In‐situ IL‐35 detection was performed by immunohistochemical staining and Western blot. The n‐vitro effect of IL‐35 on CD4+ or CD8+ T cell function was detected by flow cytometry. Our results showed that there were large amounts of IL‐35 expressed in HCC serum and tumor tissues. IL‐35 expression affects the transcript of thousands of genes, most differentially expressed genes (DEGs), in tumor tissues correlated with T cell immunity. The IL‐35 high‐expression group exhibited enhancement of regulatory T cells (Tregs) and impairment of cytolytic T cells. In‐vitro experiments proved that exogenous IL‐35 stimulated the expression of programmed cell death 1 (PD‐1) and lymphocyte activation gene‐3 (LAG3) in CD4+ and CD8+ T cells. In addition, the stimulating effect was time‐dependent. Furthermore, IL‐35 inhibited interferon (IFN)‐γ secretion by CD4+ and CD8+ T cells. Elevated IL‐35 had an immune suppressive role in HCC tumor microenvironments through affecting inhibitor receptor expression and cytokine secretion of CD4+ and CD8+ T cells. Dissection of the precise targets and underlying molecular mechanisms would mean alternative treatments for HCC patients. [ABSTRACT FROM AUTHOR]

Summary: Tumor necrosis factor (TNF)‐α is largely regarded as a proinflammatory cytokine, but several recent researches have demonstrated that TNF‐α could possess immunoregulatory roles with potential to suppress anti‐tumor immunity. Chronic hepatitis B virus (HBV) infection is a major risk factor of hepatocellular carcinoma (HCC), and HBV‐specific CD8 T cells could exert anti‐tumor roles in HCC patients. Here, we found that HBV‐specific CD8 T cells, both in the peripheral blood and in the tumor microenvironment, were more enriched with TNF‐α‐expressing cells than interferon (IFN)‐γ‐expressing cells. Compared to IFN‐γ‐expressing HBV‐specific CD8 T cells, TNF‐α‐expressing HBV‐specific CD8 T cells presented lower expression of inhibitory checkpoint molecules, including programmed cell death (PD)‐1, T cell immunoglobulin mucin‐3 (TIM‐3) and cytotoxic T lymphocyte antigen (CTLA)‐4. HBV‐specific CD8 T cells could mediate the lysis of autologous primary tumor cells, and the inhibition of TNF‐α could further elevate their cytotoxic capacity. Subsequently, we demonstrated that TNF‐α inhibition in HBV‐specific CD8 T cells could significantly increase granzyme B (GZMB) and perforin 1 (PRF1) expression while having no effect towards granzyme A (GZMA) expression. The addition of exogenous TNF‐α at low levels had no consistent effect on the expression of GZMA, GZMB and PRF1, but at higher levels, exogenous TNF‐α significantly reduced GZMA, GZMB and PRF1 expression. Overall, these results suggested that TNF‐α‐expressing cells probably presented a deleterious role in HCC but were enriched in HBV‐specific CD8 T cells. [ABSTRACT FROM AUTHOR]

Summary: Immune checkpoint inhibition has revolutionized the treatment of several solid cancers, most notably melanoma and non‐small‐cell lung cancer (NSCLC). Drugs targeting cytotoxic T lymphocyte antigen (CTLA)‐4 and programmed cell death 1 (PD‐1) have made their way into routine clinical use; however, this has not been without difficulties. Stimulation of the immune system to target cancer has been found to result in a reduction of self‐tolerance, leading to the development of adverse effects that resemble autoimmunity. These adverse effects are erratic in their onset and severity and can theoretically affect any organ type. Several mechanisms for immune‐related toxicity have been investigated over recent years; however, no consensus on the cause or prediction of toxicity has been reached. This review seeks to examine reported evidence for possible mechanisms of toxicity, methods for prediction of those at risk and a discussion of future prospects within the field. [ABSTRACT FROM AUTHOR]

Summary: The immune response is governed by a highly complex set of interactions among cells and mediators. T cells may be rendered dysfunctional by the presence of high levels of antigen in the absence of co‐stimulation while myeloid cells may be programmed towards an immunosuppressive state that promotes cancer growth and metastasis while deterring tumor immunity. In addition, inhibitory programs driven by immune checkpoint regulators dampen anti‐tumor immunity. The ideal cancer immunotherapy treatment will improve both cross‐priming in the tumor microenvironment and relieve suppression by the inhibitory checkpoints. Recently, blockade of programmed cell death 1 (PD‐1) and cytotoxic T lymphocyte antigen 4 (CTLA‐4) has elicited impressive results, but not in all patients, so additional targets are under investigation. V‐set immunoglobulin domain suppressor of T cell activation (VISTA) is a novel immunoregulatory receptor that is broadly expressed on cells of the myeloid and lymphoid lineages, and is frequently implicated as a poor prognostic indicator in multiple cancers. Importantly, antibody targeting of VISTA uniquely engages both innate and adaptive immunity. This, combined with the expression of VISTA and its non‐redundant activities compared to other immune checkpoint regulators, qualifies VISTA to be a promising target for improving cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Summary: Cytotoxic T lymphocyte antigen‐4‐immunoglobulin (CTLA‐4‐Ig) exerts anti‐rheumatic action via negative regulation of the co‐stimulation process between antigen‐presenting cells and T cells. CTLA‐4‐Ig also binds to CD80/CD86 on monocytes of osteoclast precursors. However, little is known about the effect of CTLA‐4‐Ig on osteoclastogenesis in rheumatoid arthritis (RA). In this study we evaluated the effects of CTLA‐4‐Ig on osteoclast generation from human blood monocytes (PBM) and rheumatoid synovial fluid monocytes (RSFM). Highly purified monocytes were cultured with receptor activator of nuclear factor kappa‐B ligand (RANKL) and macrophage colony‐stimulating factor (M‐CSF) in the presence of CTLA‐4‐Ig. CTLA‐4‐Ig inhibited RANKL‐induced osteoclast generation in PBM and RSFM, as determined by tartrate‐resistant acid phosphatase (TRAP) staining and bone resorption assay using osteo assay surface plates. In addition, CTLA‐4‐Ig reduced the gene and protein expressions of nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) and cathepsin K during osteoclastogenesis. Furthermore, CTLA‐4‐Ig significantly inhibited cell proliferation during osteoclastogenesis. Interestingly, the gene expression of indoleamine 2,3‐dioxygenase‐1, an inducer of apoptosis, was enhanced by CTLA‐4‐Ig. We next examined the effect of tumour necrosis factor (TNF)‐α, a major inflammatory cytokine in rheumatoid synovium, on the expression of CD80 and CD86 by flow cytometric analysis. TNF‐α potently induced the surface expression of CD80, which is known to have much higher affinity to CTLA‐4‐Ig than CD86, and this induction was observed at mRNA levels. Interestingly, freshly prepared rheumatoid synovial monocytes also expressed CD80 as much as TNF‐α‐treated PBM. Furthermore, TNF‐α enhanced CTLA‐4‐Ig‐induced inhibition of osteoclastogenesis and cell proliferation. Taken together, the TNF‐α‐induced CD80 may augment CTLA‐4‐Ig‐induced inhibition of osteoclastogenesis, suggesting that CTLA‐4‐Ig potently inhibits osteoclast differentiation and protects bone destruction in rheumatoid inflamed joints. [ABSTRACT FROM AUTHOR]

Summary: Regulatory T cells (Tregs) modulate the magnitude of immune responses and possess therapeutic potential in an array of immune diseases. Statins reduce the activation and proliferation of conventional T cells (Tcons), and they seem to up‐regulate the frequency and function of Tregs. However, there is a lack of simultaneous evaluation of the in‐vitro effect of statins on the functional profile of Tregs versus Tcons. Herein, magnetically purified Tcons and Tregs were stimulated with CD3/CD28/interleukin (IL)‐2 in the presence of atorvastatin (ATV) at 1 or 10 µM. The suppressive function of Tregs, the expression of markers associated with Treg function, activation levels, cytokine production and calcium flux in both subpopulations were assessed by flow cytometry. ATV had no cytotoxic effect on T cells at the concentrations used. Interestingly, 10 µM ATV hampered the suppressive capacity of Tregs. Moreover, this higher concentration reduced the expression of forkhead box protein 3 (FoxP3), cytotoxic T lymphocyte antigen (CTLA‐4) and programmed death 1 (PD‐1). In Tcons, ATV at 10 µM decreased PD‐1 and CD45RO expression. The expression of CD25, CD69, CD95, CD38, CD62L, CCR7 and perforin was not affected in both subpopulations or at any ATV concentrations. Remarkably, 10 µM ATV increased the percentage of tumour necrosis factor (TNF)‐α‐producing Tregs. Although there was a reduction of calcium flux in Tcons and Tregs, it was only significant in 10 µM ATV‐treated Tcons. These results suggested that 10 µM ATV affects the cellular functions of both populations; however, this concentration particularly affected several aspects of Treg biology: its suppressive function, cytokine production and expression of Treg‐specific markers. [ABSTRACT FROM AUTHOR]

Summary: Submicroscopic Plasmodium infections in pregnancy are common in endemic areas, and it is important to understand the impact of these low‐level infections. Asymptomatic, chronic infections are advantageous for parasite persistence, particularly in areas where the optimal eco‐epidemiological conditions for parasite transmission fluctuate. In chronic infections, the persistence of the antigenic stimulus changes the expression of immune mediators and promotes constant immune regulation, including increases in regulatory T cell populations. These alterations of the immune system could compromise the response to routine vaccination. This study aimed to evaluate the effect of submicroscopic plasmodial infection with P. falciparum and P. vivax during pregnancy on the immune response to the tetanus toxoid vaccine in Colombian women. Expression of different cytokines and mediators of immune regulation and levels of anti‐tetanus toxoid (TT) immunoglobulin (Ig)G were quantified in pregnant women with and without submicroscopic plasmodial infection. The anti‐TT IgG levels were significantly lower in the infected group compared with the uninfected group. The expression of interferon (IFN)‐γ, tumour necrosis factor (TNF) and forkhead box protein 3 (FoxP3) was significantly higher in the infected group, while the expression of cytotoxic T lymphocyte antigen 4 (CTLA‐4) and transforming growth factor (TGF)‐β was lower in the group of infected. In conclusion, submicroscopic Plasmodium infection altered the development of the immune response to the TT vaccine in Colombian pregnant women. The impact of Plasmodium infections on the immune regulatory pathways warrants further exploration. Submicroscopic plasmodial infection in pregnancy (SPIP) is associated with reduced antibody levels to tetanus toxoid in Colombian women, which could be explained by the inclination towards a regulatory profile of the immune response generated in those chronic plasmodial infections. [ABSTRACT FROM AUTHOR]

Our previous work revealed that the recipients with the highest pre-existing numbers of CD8+ effector T cells (TE) [hyperparathyroidism (HPT)E recipients] occupied approximately 30% of adult transplant recipients performed in our hospital. HPTE recipients demonstrated very poor clinical outcome compared with the remaining 70% of recipients with the lowest pre-existing TE (LPTE recipient). This study aimed to clarify the best combined immunosuppressive regimen related to function of cytotoxic T lymphocytes (CTLs) for HPTE recipients. Eighty-one HPTE recipients were classified into three types, according to the immunosuppressive regimens: type 1, tacrolimus (Tac)/glucocorticoid (GC); type 2, Tac/mycophenolate mofetil (MMF)/GC; and type 3, Tac/MMF. Frequencies of severe infection, rejection and hospital death were the highest in types 1 and 2, whereas the lowest occurred in type 3. The survival rate in type 3 was the highest (100%) during follow-up until post-operative day 2000. Regarding the immunological mechanism, in type 1 TE perforin and interferon (IFN)-γ were generated through the self-renewal of CD8+ central memory T cells (TCM), but decreased in the early post-transplant period due to marked down-regulation of interleukin (IL)-12 receptor beta-1 of TCM. In type 2, the self-renewal TCM did not develop, and the effector function could not be increased. In type 3, in contrast, the effectors and cytotoxicity were correlated inversely with IL-12Rβ1+ TCM levels, and increased at the highest level around the pre-transplant levels of IL-12Rβ1+ TCM. However, the immunological advantage of Tac/MMF therapy was inhibited strongly by additive steroid administration. [ABSTRACT FROM AUTHOR]

Cytotoxic T lymphocyte antigen 4 ( CTLA-4) immunoglobulin ( Ig) is an important regulator of T cell activation and a fusion protein directed at CD80 and CD86; it blocks co-stimulatory signalling and T cell activation. We have taken advantage of a murine model of human primary biliary cirrhosis ( PBC), mice expressing a transforming growth factor ( TGF)-β receptor II dominant negative ( dnTGF-β RII) transgene to address the potential therapeutic efficacy of CTLA-4 Ig. To mimic patients with PBC at different stages or duration of disease, we treated mice with either CTLA-4 Ig or control IgG three times weekly from 3 to 12 or 24 weeks of age, or from 12 to 24 weeks of age. CTLA-4 Ig treatment from 3 weeks of age significantly reduced liver inflammation to 12 weeks of age. Treatment initiated at 12 weeks of age also ameliorated the autoimmune cholangitis at 24 weeks of age. However, in mice treated at 3 weeks of age, suppression of liver inflammation was not sustained and colitis was aggravated when treatment was extended to 24 weeks of age. Our data indicate that, in dnTGF-βRII mice, CTLA-4 Ig treatment has short-term beneficial effects on autoimmune cholangitis, but the effect varies according to duration of treatment and the time in which therapy was initiated. Further dissection of the events that lead to the reduction in therapeutic effectiveness of CTLA-4 Ig will be critical to determining whether such efforts can be applied to human PBC. [ABSTRACT FROM AUTHOR]

CD8 T cells specific for islet autoantigens are major effectors of β cell damage in type 1 diabetes, and measurement of their number and functional characteristics in blood represent potentially important disease biomarkers. CD8 T cell reactivity against glutamic acid decarboxylase 65 ( GAD65) in HLA- A*0201 subjects has been reported to focus on an immunogenic region 114-123 ( VMNILLQYVV), with studies demonstrating both 114-123 and 114-122 epitopes being targeted. However, the fine specificity of this response is unclear and the key question as to which epitope(s) β cells naturally process and present and, therefore, the pathogenic potential of CD8 T cells with different specificities within this region has not been addressed. We generated human leucocyte antigen ( HLA)- A*0201-restricted CD8 T cell clones recognizing either 114-122 alone or both 114-122 and 114-123. Both clone types show potent and comparable effector functions (cytokine and chemokine secretion) and killing of indicator target cells externally pulsed with cognate peptide. However, only clones recognizing 114-123 kill target cells transfected with HLA- A*0201 and GAD2 and HLA- A*0201+ human islet cells. We conclude that the endogenous pathway of antigen processing by HLA- A*0201-expressing cells generates GAD65114-123 as the predominant epitope in this region. These studies highlight the importance of understanding β cell epitope presentation in the design of immune monitoring for potentially pathogenic CD8 T cells. [ABSTRACT FROM AUTHOR]

Mutations in the X-linked inhibitor of apoptosis ( XIAP) gene have been associated with XLP-like disease, including recurrent Epstein-Barr virus ( EBV)-related haemophagocytic lymphohystiocytosis (HLH), but the immunopathogenic bases of EBV-related disease in XIAP deficiency is unknown. We present the first analysis of EBV-specific T cell responses in functional XIAP deficiency. In a family of patients with a novel mutation in XIAP ( G466 X) leading to a late-truncated protein and varying clinical features, we identified gradual hypogammaglobulinaemia and large expansions of T cell subsets, including a prominent CD4+ CD8+ population. Extensive ex-vivo analyses showed that the expanded T cell subsets were dominated by EBV-specific cells with conserved cytotoxic, proliferative and interferon ( IFN)-γ secretion capacity. The EBV load in blood fluctuated and was occasionally very high, indicating that the XIAPG466X mutation could impact upon EBV latency. XIAP deficiency may unravel a new immunopathogenic mechanism in EBV-associated disease. [ABSTRACT FROM AUTHOR]

Studies have documented that cancer patients with tumours which are highly infiltrated with cytotoxic T lymphocytes show enhanced survival rates. The ultimate goal of cancer immunotherapy is to elicit high-avidity tumour-specific T cells to migrate and kill malignant tumours. Novel antibody therapies such as ipilumimab (a cytotoxic T lymphocyte antigen-4 blocking antibody) show enhanced T cell infiltration into the tumour tissue and increased survival. More conventional therapies such as chemotherapy or anti-angiogenic therapy and recent therapies with oncolytic viruses have been shown to alter the tumour microenvironment and thereby lead to enhanced T cell infiltration. Understanding the mechanisms involved in the migration of high-avidity tumour-specific T cells into tumours will support and provide solutions for the optimization of therapeutic options in cancer immunotherapy. [ABSTRACT FROM AUTHOR]