The CD4-like molecule LAG-3, biology and therapeutic applications

Increase of cells expressing PD-1 and PD-L1 and enhancement of IFN-γ production via PD-1/PD-L1 blockade in bovine mycoplasmosis

Introduction

Bovine mycoplasma, chiefly Mycoplasma bovis, is a pathogen that causes pneumonia, mastitis, arthritis, and otitis media in cattle. This pathogen exerts immunosuppressive effects, such as the inhibition of interferon production. However, the mechanisms involved in bovine mycoplasmosis have not been fully elucidated. In this study, we investigated the role of the programmed death‐1 (PD‐1)/programmed death‐ligand 1 (PD‐L1) pathway in immunosuppression in bovine mycoplasmosis.

Methods

In the initial experiments, we used enzyme‐linked immunosorbent assay to measure interferon‐γ (IFN‐γ) from peripheral blood mononuclear cells (PBMCs) isolated from cattle with mycoplasmosis.

Results

Expectedly, IFN‐γ production significantly decreased in cattle with mycoplasmosis compared with that in clinically healthy cattle. Concomitantly, flow cytometric analysis revealed that the proportions of PD‐1⁺CD4⁺ and PD‐L1⁺CD14⁺ cells significantly increased in peripheral blood of the infected cattle. Interestingly, the number of PD‐1⁺CD4⁺ and PD‐1⁺CD8⁺ T cells were negatively correlated with IFN‐γ production from PBMCs in bovine mycoplasmosis. Additionally, blockade of the PD‐1/PD‐L1 pathway in vitro by anti‐bovine PD‐1‐ and anti‐bovine PD‐L1 antibodies significantly upregulated the production of IFN‐γ from anti‐mycoplasma‐specific cells.

Conclusions

These results suggest that the PD‐1/PD‐L1 pathway could be involved in immune exhaustion of bovine mycoplasma‐specific T cells. In conclusion, our study opens up a new perspective in the therapeutic strategy for bovine mycoplasmosis by targeting the immunoinhibitory receptor pathways.

NK1.1- CD4+ NKG2D+ T cells suppress DSS-induced colitis in mice through production of TGF-β

CD4⁺NKG2D⁺ T cells are associated with tumour, infection and autoimmune diseases. Some CD4⁺NKG2D⁺ T cells secrete IFN‐γ and TNF‐α to promote inflammation, but others produce TGF‐β and FasL to facilitate tumour evasion. Here, murine CD4⁺NKG2D⁺ T cells were further classified into NK1.1⁻CD4⁺NKG2D⁺ and NK1.1⁺CD4⁺NKG2D⁺ subpopulations. The frequency of NK1.1⁻CD4⁺NKG2D⁺ cells decreased in inflamed colons, whereas more NK1.1⁺CD4⁺NKG2D⁺ cells infiltrated into colons of mice with DSS‐induced colitis. NK1.1⁻CD4⁺NKG2D⁺ cells expressed TGF‐β and FasL without secreting IFN‐γ, IL‐21 and IL‐17 and displayed no cytotoxicity. The adoptive transfer of NK1.1⁻CD4⁺NKG2D⁺ cells suppressed DSS‐induced colitis largely dependent on TGF‐β. NK1.1⁻CD4⁺NKG2D⁺ cells did not expressed Foxp3, CD223 (LAG‐3) and GITR. The subpopulation was distinct from NK1.1⁺CD4⁺NKG2D⁺ cells in terms of surface markers and RNA transcription. NK1.1⁻CD4⁺NKG2D⁺ cells also differed from Th2 or Th17 cells because the former did not express GATA‐3 and ROR‐γt. Thus, NK1.1⁻CD4⁺NKG2D⁺ cells exhibited immune regulatory functions, and this T cell subset could be developed to suppress inflammation in clinics.

Recent Advances in Immunotherapy in Metastatic NSCLC

Non-small cell lung cancer (NSCLC) is one of most common malignancies and the leading cause of cancer deaths worldwide. Despite advances in targeted therapies, majority of NSCLC patients do not have targetable genomic alterations. Nevertheless, recent discovery that NSCLC is an immunogenic tumor type, and several breakthroughs in immunotherapies have led to rapid expansion of this new treatment modality in NSCLC with recent FDA approvals of programed death receptor-1 inhibitors, such as nivolumab and pembrolizumab. Here, we review promising immunotherapeutic approaches in metastatic NSCLC, including checkpoint inhibitors, agents with other mechanisms of action, and immunotherapy combinations with other drugs. With advent of immunotherapy, therapeutic options in metastatic NSCLC are rapidly expanding with the hope to further expand life expectancy in metastatic lung cancer.

Lymphocyte activation gene 3 and coronary artery disease

BACKGROUND: The lipoprotein scavenger receptor BI (SCARB1) rs10846744 noncoding variant is significantly associated with atherosclerotic disease independently of traditional cardiovascular risk factors. We identified a potentially novel connection between rs10846744, the immune checkpoint inhibitor lymphocyte activation gene 3 (LAG3), and atherosclerosis. METHODS: In vitro approaches included flow cytometry, lipid raft isolation, phosphosignaling, cytokine measurements, and overexpressing and silencing LAG3 protein. Fasting plasma LAG3 protein was measured in hyperalphalipoproteinemic (HALP) and Multi-Ethnic Study of Atherosclerosis (MESA) participants. RESULTS: In comparison with rs10846744 reference (GG homozygous) cells, LAG3 protein levels by flow cytometry (P < 0.001), in lipid rafts stimulated and unstimulated (P = 0.03), and phosphosignaling downstream of B cell receptor engagement of CD79A (P = 0.04), CD19 (P = 0.04), and LYN (P = 0.001) were lower in rs10846744 risk (CC homozygous) cells. Overexpressing LAG3 protein in risk cells and silencing LAG3 in reference cells confirmed its importance in phosphosignaling. Secretion of TNF-α was higher (P = 0.04) and IL-10 was lower (P = 0.04) in risk cells. Plasma LAG3 levels were lower in HALP carriers of the CC allele (P < 0.0001) and by race (P = 0.004). In MESA, race (P = 0.0005), age (P = 0.003), lipid medications (P = 0.03), smoking history (P < 0.0001), and rs10846744 genotype (P = 0.002) were independent predictors of plasma LAG3. In multivariable regression models, plasma LAG3 was significantly associated with HDL-cholesterol (HDL-C) (P = 0.007), plasma IL-10 (P < 0.0001), and provided additional predictive value above the Framingham risk score (P = 0.04). In MESA, when stratified by high HDL-C, plasma LAG3 was associated with coronary heart disease (CHD) (odds ratio 1.45, P = 0.004). CONCLUSION: Plasma LAG3 is a potentially novel independent predictor of HDL-C levels and CHD risk. FUNDING: This work was supported by an NIH RO1 grant (HL075646), the endowed Linda and David Roth Chair for Cardiovascular Research, and the Harold S. Geneen Charitable Trust Coronary Heart Disease Research award to Annabelle Rodriguez. MESA is conducted and supported by the National Heart, Lung, and Blood Institute (NHLBI) in collaboration with MESA investigators. Support for MESA is provided by contracts HHSN268201500003I, N01-HC-95159, N01-HC-95160, N01-HC-95161, N01-HC-95162, N01-HC-95163, N01-HC-95164, N01-HC-95165, N01-HC-95166, N01-HC-95167, N01-HC-95168, N01-HC-95169, UL1-TR-001079, UL1-TR-000040, and DK063491. Cardiometabochip genotyping data for the MESA samples was supported in part by grants and contracts R01HL98077, N02-HL-64278, HL071205, UL1TR000124, DK063491, RD831697, and P50 ES015915.

LAG-3 confers poor prognosis and its blockade reshapes antitumor response in head and neck squamous cell carcinoma

Immunotherapy with immune checkpoint molecule-specific monoclonal antibody have obtained encouraging results from preclinical studies and clinical trials, which promoted us to explore whether this kind of immunotherapy could be applicable to head and neck squamous cell carcinoma (HNSCC). Lymphocyte activation gene-3 (LAG-3) is an immune checkpoint control protein that negatively regulates T cells and immune response. Here, using the human tissue samples, we report these findings that LAG-3 is overexpressed on tumor-infiltrating lymphocytes (TILs; p < 0.001) and its overexpression correlates with the high pathological grades, lager tumor size and positive lymph node status in human primary HNSCC. Survival analysis identifies LAG-3 as a prognostic factor independent of tumor size and pathological grades for primary HNSCC patients with negative lymph node status (p = 0.014). Study in immunocompetent genetically defined HNSCC mouse model reports that LAG-3 is upregulated on CD4⁺ T cells, CD8⁺ T cells and CD4⁺Foxp3⁺ regulatory T cells (Tregs). In vivo study, administration of LAG-3-specific antibody retards tumor growth in a way associated with enhanced systemic antitumor response by potentiating the antitumor response of CD8⁺ T cells and decreasing the population of immunosuppressive cells. Taken together, our results offer a preclinical proof supporting the immunomodulatory effects of LAG-3 and suggest a potential therapeutic target of immunotherapy for HNSCC.

Cooperation of PD-1 and LAG-3 Contributes to T-Cell Exhaustion in Anaplasma marginale-Infected Cattle

The CD4(+) T-cell response is central for the control of Anaplasma marginale infection in cattle. However, the infection induces a functional exhaustion of antigen-specific CD4(+) T cells in cattle immunized with A. marginale outer membrane proteins or purified outer membranes (OMs), which presumably facilitates the persistence of this rickettsia. In the present study, we hypothesize that T-cell exhaustion following infection is induced by the upregulation of immunoinhibitory receptors on T cells, such as programmed death 1 (PD-1) and lymphocyte activation gene 3 (LAG-3). OM-specific T-cell responses and the kinetics of PD-1-positive (PD-1(+)) LAG-3(+) exhausted T cells were monitored in A. marginale-challenged cattle previously immunized with OMs. Consistent with data from previous studies, OM-specific proliferation of peripheral blood mononuclear cells (PBMCs) and interferon gamma (IFN-γ) production were significantly suppressed in challenged animals by 5 weeks postinfection (wpi). In addition, bacteremia and anemia also peaked in these animals at 5 wpi. Flow cytometric analysis revealed that the percentage of PD-1(+) LAG-3(+) T cells in the CD4(+), CD8(+), and γδ T-cell populations gradually increased and also peaked at 5 wpi. A large increase in the percentage of LAG-3(+) γδ T cells was also observed. Importantly, in vitro, the combined blockade of the PD-1 and LAG-3 pathways partially restored OM-specific PBMC proliferation and IFN-γ production at 5 wpi. Taken together, these results indicate that coexpression of PD-1 and LAG-3 on T cells contributes to the rapid exhaustion of A. marginale-specific T cells following infection and that these immunoinhibitory receptors regulate T-cell responses during bovine anaplasmosis.

Mini-intronic plasmid vaccination elicits tolerant LAG3+ CD8+ T cells and inferior antitumor responses

Increasing transgene expression has been a major focus of attempts to improve DNA vaccine-induced immunity in both preclinical studies and clinical trials. Novel mini-intronic plasmids (MIPs) have been shown to cause elevated and sustained transgene expression in vivo. We sought to test the antitumor activity of a MIP, compared to standard DNA plasmid immunization, using the tumor-specific antigen SSX2 in an HLA-A2-restricted tumor model. We found that MIP vaccination elicited a greater frequency of antigen-specific CD8⁺ T cells when compared to conventional plasmid, and protected animals from subsequent tumor challenge. However, therapeutic vaccination with the MIP resulted in an inferior antitumor effect, and CD8⁺ tumor-infiltrating lymphocytes from these mice expressed higher levels of surface LAG3. Antitumor efficacy of MIP vaccination could be recovered upon antibody blockade of LAG3. In non-tumor bearing mice, MIP immunization led to a loss of epitope dominance, attenuated CD8⁺ cytokine responses to the dominant p103 epitope, and increased LAG3 expression on p103-specific CD8⁺ T cells. Further, LAG3 expression on CD8⁺ T cells was associated with antigen dose and persistence in spite of DNA-induced innate immunity. These data suggest that for antitumor immunization, approaches leading to increased antigen expression following vaccination might optimally be combined with LAG3 inhibition in human trials. On the other hand, mini-intronic vector approaches may be a superior means to elicit LAG3-dependent tolerance in the treatment of autoimmune diseases.

Recent developments and future challenges in immune checkpoint inhibitory cancer treatment

PURPOSE OF REVIEW

In this review, we focus on the recent findings and future challenges in cancer treatment with immune checkpoint inhibitors.

RECENT FINDINGS

Major progress has been made in recent years as the first immune checkpoint inhibitors are approved by the US Food and Drug Administration for the treatment of cancer patients. Anticytotoxic T-lymphocyte-associated protein 4 and antiprogrammed death protein 1/programmed death-ligand 1 (PD-L1) monoclonal antibodies are being extensively studied in many different tumor types, often showing impressive response rates, but also a typical serious toxicity profile in the form of auto-immunity. Unfortunately, it is not yet possible to prevent or predict these immune-related adverse events. Studies on mutational load, neo-epitopes, lactate dehydrogenase, PD-L1 expression, and T-cell infiltration suggest that these markers are correlating with efficacy, but have not yet reached the status of a validated biomarker for checkpoint inhibitors. Other immune checkpoints are being investigated and new checkpoint inhibitors are on the brink of being evaluated in clinical trials.

SUMMARY

The main challenge for the near future will be to predict efficacy of immune checkpoint blockade and to predict and prevent immune-related adverse events. More research should be done in order to find potential biomarkers that predict treatment response and/or toxicity; the optimal administration route, dosage, and frequency; and possible combinations of therapies that have an added or synergetic effect.

Potential of immunomodulatory agents as adjunct host-directed therapies for multidrug-resistant tuberculosis

Treatment of multidrug-resistant tuberculosis (MDR-TB) is extremely challenging due to the virulence of the etiologic strains of Mycobacterium tuberculosis (M. tb), the aberrant host immune responses and the diminishing treatment options with TB drugs. New treatment regimens incorporating therapeutics targeting both M. tb and host factors are urgently needed to improve the clinical management outcomes of MDR-TB. Host-directed therapies (HDT) could avert destructive tuberculous lung pathology, facilitate eradication of M. tb, improve survival and prevent long-term functional disability. In this review we (1) discuss the use of HDT for cancer and other infections, drawing parallels and the precedent they set for MDR-TB treatment, (2) highlight preclinical studies of pharmacological agents commonly used in clinical practice which have HDT potential, and (3) outline developments in cellular therapy to promote clinically beneficial immunomodulation to improve treatment outcomes in patients with pulmonary MDR-TB. The use of HDTs as adjuncts to MDR-TB therapy requires urgent evaluation.

Cancer immunotherapy: the beginning of the end of cancer?

These are exciting times for cancer immunotherapy. After many years of disappointing results, the tide has finally changed and immunotherapy has become a clinically validated treatment for many cancers. Immunotherapeutic strategies include cancer vaccines, oncolytic viruses, adoptive transfer of ex vivo activated T and natural killer cells, and administration of antibodies or recombinant proteins that either costimulate cells or block the so-called immune checkpoint pathways. The recent success of several immunotherapeutic regimes, such as monoclonal antibody blocking of cytotoxic T lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD1), has boosted the development of this treatment modality, with the consequence that new therapeutic targets and schemes which combine various immunological agents are now being described at a breathtaking pace. In this review, we outline some of the main strategies in cancer immunotherapy (cancer vaccines, adoptive cellular immunotherapy, immune checkpoint blockade, and oncolytic viruses) and discuss the progress in the synergistic design of immune-targeting combination therapies.

Immune checkpoint inhibitors enhance cytotoxicity of cytokine-induced killer cells against human myeloid leukaemic blasts

We studied whether blockade of inhibitory receptors on cytokine-induced killer (CIK) cells by immune checkpoint inhibitors could increase its anti-tumour potency against haematological malignancies. CIK cultures were generated from seven normal donors and nine patients with acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL) or multiple myeloma (MM). The inhibitory receptors B and T lymphocyte attenuator, CD200 receptor, lymphocyte activation gene-3 (LAG-3) and T cell immunoglobulin and mucin-domain-containing-3 (TIM-3) were present at variable percentages in most CIK cultures, while cytotoxic T lymphocyte-associated protein 4 (CTLA-4), programmed death-1 (PD-1) and killer cell immunoglobulin-like receptors (KIR2DL1/2/3) were expressed at low level in most cultures. Without blockade, myeloid leukaemia cells were susceptible to autologous and allogeneic CIK-mediated cytotoxicity. Blockade of KIR, LAG-3, PD-1 and TIM-3 but not CTLA-4 resulted in remarkable increase in killing against these targets, even in those with poor baseline cytotoxicity. ALL and MM targets were resistant to CIK-mediated cytotoxicity, and blockade of receptors did not increase cytotoxicity to a meaningful extent. Combination of inhibitors against two receptors did not further increase cytotoxicity. Interestingly, potentiation of CIK killing by blocking antibodies was not predicted by expression of receptors on CIK and their respective ligands on the targets. Compared to un-activated T and NK cells, blockade potentiated the cytotoxicity of CIK cells to a greater degree and at a lower E:T ratio, but without significant increase in cytotoxicity against normal white cell. Our findings provide the basis for clinical trial combining autologous CIK cells with checkpoint inhibitors for patients with AML.

Characterisation of the clinical and activated T cell response to repeat delayed-type hypersensitivity skin challenges in human subjects, with KLH and PPD, as a potential model to test T cell-targeted therapies

OBJECTIVE

To characterise the delayed-type hypersensitivity (DTH) skin reaction to repeated challenges of keyhole limpet hemocyanin (KLH) and tuberculin purified protein derivative (PPD) in healthy volunteers, as a potential model to test T cell-targeted investigational agents.

SUBJECTS, TREATMENT AND METHODS

Forty-nine subjects received either KLH, PPD, or PBS repeat skin challenges, and clinical assessments including induration, erythema and Laser Doppler Imaging. Skin biopsies or suction blisters were taken after challenge to investigate the cellular infiltrate of the challenge site, the T cell activation status, as determined by LAG-3 expression, and, specifically for the blister, the concentrations of inflammatory cytokines. Point estimates, estimates of variation and corresponding 95% confidence intervals were constructed for each type of challenge and timepoint.

RESULTS

The DTH response could be measured at 48 and 120 h post-KLH and PPD challenge with induration, erythema and Laser Doppler Imaging, with 48 h post-challenge demonstrating the peak of the response. PPD was well tolerated in subjects after multiple challenges, however, a significant number of KLH-treated subjects demonstrated an injection site reaction 6-7 days following the SC injection. PPD demonstrated a boost effect on the second challenge as measured by increased induration, where as this was not noted consistently for KLH. Compared to unchallenged and PBS control-injected skin, increased T cell numbers were detected in the challenge site by both the skin suction blister and biopsy technique, at either time point following KLH or PPD challenge. Use of the T cell activation marker LAG-3 demonstrated the activated phenotype of these cells. In skin blisters, higher numbers of LAG-3+ T cells were detected at 48 h post-challenge, whereas in the biopsies, similar numbers of LAG-3+ cells were observed at both 48 and 120 h. Analysis of blister T cell subpopulations revealed some differences in phenotypes between the time points and between the CD4 and CD8 T cells. Blister cytokine analysis revealed a pro-inflammatory dominated signature in PPD-challenged skin.

CONCLUSIONS

In summary, our data support the use of a repeat KLH and PPD DTH challenge in clinical trials and that the clinical measures of induration and to a lesser extent erythema are appropriate to monitor the clinical DTH response. Both the blister and biopsy can be utilised to assess and quantify activated T cells and at the dose used, PPD was better tolerated than KLH and hence may be optimal for future studies.

Clostridium novyi-NT in cancer therapy

The attenuated anaerobic bacterium Clostridium novyi-NT (C. novyi-NT) is known for its ability to precisely germinate in and eradicate treatment-resistant hypoxic tumors in various experimental animal models and spontaneously occurring canine sarcomas. In this article, we review the therapeutic and toxicologic aspects of C. novyi-NT therapy, key challenges and limitations, and promising strategies to optimize its performance via recombinant DNA technology and immunotherapeutic approaches, to establish C. novyi-NT as an essential tool in cancer therapy.

Innovative perspectives of immunotherapy in head and neck cancer. From relevant scientific rationale to effective clinical practice

It is now well established that head and neck cancer carcinogenesis is characterized by genetic instability and several immune defects, leading to unique host-tumor interactions. In such condition, recent improved comprehension and relevant findings could lead to identification of innovative molecular therapeutic targets, achieving considerable clinical and translational research. This review aims to summarize and to highlight most recent and relevant scientific rationale in this era of immunotherapy revival, and to correlate it to the near future clinical practice for the management of this challenging disease.

Novel cancer antigens for personalized immunotherapies: latest evidence and clinical potential

The clinical success of monoclonal antibody immune checkpoint modulators such as ipilimumab, which targets cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), and the recently approved agents nivolumab and pembrolizumab, which target programmed cell death receptor 1 (PD-1), has stimulated renewed enthusiasm for anticancer immunotherapy, which was heralded by Science as 'Breakthrough of the Year' in 2013. As the potential of cancer immunotherapy has been recognized since the 1890s when William Coley showed that bacterial products could be beneficial in cancer patients, leveraging the immune system in the treatment of cancer is certainly not a new concept; however, earlier attempts to develop effective therapeutic vaccines and antibodies against solid tumors, for example, melanoma, frequently met with failure due in part to self-tolerance and the development of an immunosuppressive tumor microenvironment. Increased knowledge of the mechanisms through which cancer evades the immune system and the identification of tumor-associated antigens (TAAs) and negative immune checkpoint regulators have led to the development of vaccines and monoclonal antibodies targeting specific tumor antigens and immune checkpoints such as CTLA-4 and PD-1. This review first discusses the established targets of currently approved cancer immunotherapies and then focuses on investigational cancer antigens and their clinical potential. Because of the highly heterogeneous nature of tumors, effective anticancer immunotherapy-based treatment regimens will likely require a personalized combination of therapeutic vaccines, antibodies and chemotherapy that fit the specific biology of a patient's disease.

Combinatorial Cancer Immunotherapies

T cell checkpoint blockade therapies are revolutionizing the treatment of patients with cancer. Highlighted by the recent success of PD-1 plus CTLA-4 blockade in patients with melanomas, synergistic immunotherapy combinations of modalities represent an important opportunity to improve responses and outcomes for patients. We review the rationale and experience with T cell checkpoint blockade in combination with targeting of other coinhibitory or costimulatory checkpoints, immunomodulatory molecules in the tumor microenvironment, and other anticancer modalities such as vaccines, chemotherapy, and radiation.

LAG-3 confers poor prognosis and its blockade reshapes antitumor response in head and neck squamous cell carcinoma

Immunotherapy with immune checkpoint molecule-specific monoclonal antibody have obtained encouraging results from preclinical studies and clinical trials, which promoted us to explore whether this kind of immunotherapy could be applicable to head and neck squamous cell carcinoma (HNSCC). Lymphocyte activation gene-3 (LAG-3) is an immune checkpoint control protein that negatively regulates T cells and immune response. Here, using the human tissue samples, we report these findings that LAG-3 is overexpressed on tumor-infiltrating lymphocytes (TILs; p < 0.001) and its overexpression correlates with the high pathological grades, lager tumor size and positive lymph node status in human primary HNSCC. Survival analysis identifies LAG-3 as a prognostic factor independent of tumor size and pathological grades for primary HNSCC patients with negative lymph node status (p = 0.014). Study in immunocompetent genetically defined HNSCC mouse model reports that LAG-3 is upregulated on CD4⁺ T cells, CD8⁺ T cells and CD4⁺Foxp3⁺ regulatory T cells (Tregs). In vivo study, administration of LAG-3-specific antibody retards tumor growth in a way associated with enhanced systemic antitumor response by potentiating the antitumor response of CD8⁺ T cells and decreasing the population of immunosuppressive cells. Taken together, our results offer a preclinical proof supporting the immunomodulatory effects of LAG-3 and suggest a potential therapeutic target of immunotherapy for HNSCC.

Lymphocyte activation gene 3 negatively regulates the function of intrahepatic hepatitis C virus-specific CD8+ T cells

BACKGROUND AND AIM

Chronic hepatitis C (CHC) in humans caused by persistent hepatitis C virus (HCV) infection is a global public health problem. The functional exhaustion of HCV-specific CD8(+) T cells regulated by several inhibitory receptors has been shown to contribute to chronic HCV infection. Lymphocyte activation gene 3 (LAG-3), which is an inhibitory receptor, plays an important role in several chronic viral infections. However, its effect on the function of HCV-specific CD8(+) T cells is unclear.

METHODS

The expression of LAG-3 on the CD8(+) T cells in intrahepatic and peripheral lymphocytes from 17 CHC patients and 15 HCV-negative patients was analyzed by flow cytometry. The LAG-3 expression in CD8(+) T cells was downregulated or upregulated by lentivirus LAG-3 shRNA or lentivirus overexpressing LAG-3. After HCV peptide stimulation, flow cytometry was used to detect cell proliferation and cytokine (γ-interferon [IFN-γ], tumor necrosis factor-α [TNF-α], granzyme B, and perforin) production of CD8(+) T cells. Cytotoxicity functions of HCV-specific CD8(+) T cells were measured using a (51) Cr release assay.

RESULTS

The frequency of LAG-3-positive intrahepatic and peripheral CD8(+) T cells was higher in CHC patients, compared with HCV-negative patients. The cell proliferation, cytokine (IFN-γ, TNF-α, granzyme B, and perforin) expression and cytotoxicity function of HCV-specific CD8(+) T cells in CHC patients were increased by the knocking down and blockade of LAG-3. In the LAG-3 overexpressed CD8(+) T cells, cell proliferation, cytokine (IFN-γ, TNF-α, granzyme B, and perforin) expression, and cytotoxicity function were inhibited, while the LAG-3 blocking antibody reversed the inhibition.

CONCLUSION

LAG-3 negatively regulated the function of HCV-specific CD8(+) T cells in CHC patients.

Bovine Immunoinhibitory Receptors Contribute to Suppression of Mycobacterium avium subsp. paratuberculosis-Specific T-Cell Responses

Johne's disease (paratuberculosis) is a chronic enteritis in cattle that is caused by intracellular infection with Mycobacterium avium subsp. paratuberculosis. This infection is characterized by the functional exhaustion of T-cell responses to M. avium subsp. paratuberculosis antigens during late subclinical and clinical stages, presumably facilitating the persistence of this bacterium and the formation of clinical lesions. However, the mechanisms underlying T-cell exhaustion in Johne's disease are poorly understood. Thus, we performed expression and functional analyses of the immunoinhibitory molecules programmed death-1 (PD-1)/PD-ligand 1 (PD-L1) and lymphocyte activation gene 3 (LAG-3)/major histocompatibility complex class II (MHC-II) in M. avium subsp. paratuberculosis-infected cattle during the late subclinical stage. Flow cytometric analyses revealed the upregulation of PD-1 and LAG-3 in T cells in infected animals, which suffered progressive suppression of interferon gamma (IFN-γ) responses to the M. avium subsp. paratuberculosis antigen. In addition, PD-L1 and MHC-II were expressed on macrophages from infected animals, consistent with PD-1 and LAG-3 pathways contributing to the suppression of IFN-γ responses during the subclinical stages of M. avium subsp. paratuberculosis infection. Furthermore, dual blockade of PD-L1 and LAG-3 enhanced M. avium subsp. paratuberculosis-specific IFN-γ responses in blood from infected animals, and in vitro LAG-3 blockade enhanced IFN-γ production from M. avium subsp. paratuberculosis-specific CD4(+) and CD8(+) T cells. Taken together, the present data indicate that M. avium subsp. paratuberculosis-specific T-cell exhaustion is in part mediated by PD-1/PD-L1 and LAG-3/MHC-II interactions and that LAG-3 is a molecular target for the control of M. avium subsp. paratuberculosis-specific T-cell responses.

Melanoma: oncogenic drivers and the immune system

Advances and in-depth understanding of the biology of melanoma over the past 30 years have contributed to a change in the consideration of melanoma as one of the most therapy-resistant malignancies. The finding that oncogenic BRAF mutations drive tumor growth in up to 50% of melanomas led to a molecular therapy revolution for unresectable and metastatic disease. Moving beyond BRAF, inactivation of immune regulatory checkpoints that limit T cell responses to melanoma has provided targets for cancer immunotherapy. In this review, we discuss the molecular biology of melanoma and we focus on the recent advances of molecularly targeted and immunotherapeutic approaches.

CD8+ T cell exhaustion, suppressed gamma interferon production, and delayed memory response induced by chronic Brucella melitensis infection

Brucella melitensis is a well-adapted zoonotic pathogen considered a scourge of mankind since recorded history. In some cases, initial infection leads to chronic and reactivating brucellosis, incurring significant morbidity and economic loss. The mechanism by which B. melitensis subverts adaptive immunological memory is poorly understood. Previous work has shown that Brucella-specific CD8(+) T cells express gamma interferon (IFN-γ) and can transition to long-lived memory cells but are not polyfunctional. In this study, chronic infection of mice with B. melitensis led to CD8(+) T cell exhaustion, manifested by programmed cell death 1 (PD-1) and lymphocyte activation gene 3 (LAG-3) expression and a lack of IFN-γ production. The B. melitensis-specific CD8(+) T cells that produced IFN-γ expressed less IFN-γ per cell than did CD8(+) cells from uninfected mice. Both memory precursor (CD8(+) LFA1(HI) CD127(HI) KLRG1(LO)) and long-lived memory (CD8(+) CD27(HI) CD127(HI) KLRG1(LO)) cells were identified during chronic infection. Interestingly, after adoptive transfer, mice receiving cells from chronically infected animals were able to contain infection more rapidly than recipients of cells from acutely infected or uninfected donors, although the proportions of exhausted CD8(+) T cells increased after adoptive transfer in both challenged and unchallenged recipients. CD8(+) T cells of challenged recipients initially retained the stunted IFN-γ production found prior to transfer, and cells from acutely infected mice were never seen to transition to either memory subset at all time points tested, up to 30 days post-primary infection, suggesting a delay in the generation of memory. Here we have identified defects in Brucella-responsive CD8(+) T cells that allow chronic persistence of infection.

PD-1 and PD-L1 blockade in gastrointestinal malignancies

Immunotherapy represents a major breakthrough in cancer therapy in recent years. Immune-checkpoint blockade using PD-1 and PD-L1 antibodies appears to be one of the most promising immunotherapy approaches. Immunotherapy differs from conventional cancer treatment because of its ability to produce durable responses in some patients. In this review article, we explore the available evidence and summarise current clinical trials for PD-1 and PD-L1 blockade in gastrointestinal malignancies. The challenge now is to develop strategies to increase the efficacy of PD-1 and PD-L1 blockade in gastrointestinal cancer patients, such as combination therapy with chemotherapy, radiotherapy or other immunotherapy, along with validating biomarkers to select patients and personalise treatment.

Prospects of immune checkpoint modulators in the treatment of glioblastoma

Glioblastoma is the most common primary brain tumour in adults. Prognosis is poor: even with the current gold-standard first-line treatment—maximal safe resection and combination of radiotherapy with temozolomide chemotherapy—the median overall survival time is only approximately 15-17 months, because the tumour recurs in virtually all patients, and no commonly accepted standard treatment for recurrent disease exists. Several targeted agents have failed to improve patient outcomes in glioblastoma. Immunotherapy with immune checkpoint inhibitors such as ipilimumab, nivolumab, and pembrolizumab has provided relevant clinical improvements in other advanced tumours for which conventional therapies have had limited success, making immunotherapy an appealing strategy in glioblastoma. This Review summarizes current knowledge on immune checkpoint modulators and evaluates their potential role in glioblastoma on the basis of preclinical studies and emerging clinical data. Furthermore, we discuss challenges that need to be considered in the clinical development of drugs that target immune checkpoint pathways in glioblastoma, such as specific properties of the immune system in the CNS, issues with radiological response assessment, and potential interactions with established and emerging treatment strategies.

Combination of radiotherapy and immune checkpoint inhibitors

The ability of ionizing radiation to cause cell death and inflammatory reactions has been known since the beginning of its therapeutic use in oncology. However, only recently this property of radiation has attracted the attention of immunologists seeking to induce or improve antitumor immunity. As immune checkpoint inhibitors are becoming mainstream cancer treatments, radiation oncologists have begun to observe unexpected out-of-the-field (abscopal) responses in patients receiving radiation therapy during immunotherapy. These unexpected responses were predicted by experimental work in preclinical tumor models and have clear biological bases. Accumulating experimental evidence that radiation induces an immunogenic cell death and promotes recruitment and function of T cells within the tumor microenvironment supports the hypothesis that radiation can convert the tumor into an in situ individualized vaccine. This property of radiation is key to its synergy with immune checkpoint inhibitors, antibodies targeting inhibitory receptors on T cells such as cytotoxic T lymphocyte antigen-4 and programmed death-1. By removing the obstacles hindering the activation and function of antitumor T cells, these agents benefit patients with pre-existing antitumor immunity but are ineffective in patients lacking these spontaneous responses. Radiation induces antitumor T cells complementing the activity of immune checkpoint inhibitors.

Evolving synergistic combinations of targeted immunotherapies to combat cancer

Immunotherapy has now been clinically validated as an effective treatment for many cancers. There is tremendous potential for synergistic combinations of immunotherapy agents and for combining immunotherapy agents with conventional cancer treatments. Clinical trials combining blockade of cytotoxic T lymphocyte-associated antigen 4 (CTLA4) and programmed cell death protein 1 (PD1) may serve as a paradigm to guide future approaches to immuno-oncology combination therapy. In this Review, we discuss progress in the synergistic design of immune-targeting combination therapies and highlight the challenges involved in tailoring such strategies to provide maximal benefit to patients.

Inhibitory Receptors Beyond T Cell Exhaustion

Inhibitory receptors (iRs) are frequently associated with "T cell exhaustion". However, the expression of iRs is also dependent on T cell differentiation and activation. Therapeutic blockade of various iRs, also referred to as "checkpoint blockade", is showing -unprecedented results in the treatment of cancer patients. Consequently, the clinical potential in this field is broad, calling for increased research efforts and rapid refinements in the understanding of iR function. In this review, we provide an overview on the significance of iR expression for the interpretation of T cell functionality. We summarize how iRs have been strongly associated with "T cell exhaustion" and illustrate the parallel evidence on the importance of T cell differentiation and activation for the expression of iRs. The differentiation subsets of CD8 T cells (naïve, effector, and memory cells) show broad and inherent differences in iR expression, while activation leads to strong upregulation of iRs. Therefore, changes in iR expression during an immune response are often concomitant with T cell differentiation and activation. Sustained expression of iRs in chronic infection and in the tumor microenvironment likely reflects a specialized T cell differentiation. In these situations of prolonged antigen exposure and chronic inflammation, T cells are "downtuned" in order to limit tissue damage. Furthermore, we review the novel "checkpoint blockade" treatments and the potential of iRs as biomarkers. Finally, we provide recommendations for the immune monitoring of patients to interpret iR expression data combined with parameters of activation and differentiation of T cells.

Cannabidiol, a non-psychoactive cannabinoid, leads to EGR2-dependent anergy in activated encephalitogenic T cells

Background

Cannabidiol (CBD), the main non-psychoactive cannabinoid, has been previously shown by us to ameliorate clinical symptoms and to decrease inflammation in myelin oligodendrocyte glycoprotein (MOG)35-55-induced mouse experimental autoimmune encephalomyelitis model of multiple sclerosis as well as to decrease MOG35-55-induced T cell proliferation and IL-17 secretion. However, the mechanisms of CBD anti-inflammatory activities are unclear.

Methods

Here we analyzed the effects of CBD on splenocytes (source of accessory T cells and antigen presenting cells (APC)) co-cultured with MOG35-55-specific T cells (T_MOG) and stimulated with MOG35-55. Using flow cytometry, we evaluated the expression of surface activation markers and inhibitory molecules on T cells and B cells. T_MOG cells were purified using CD4 positive microbead selection and submitted for quantitative PCR and microarray of mRNA transcript analyzes. Cell signaling studies in purified T_MOG were carried out using immunoblotting.

Results

We found that CBD leads to upregulation of CD69 and lymphocyte-activation gene 3 (LAG3) regulatory molecules on CD4⁺CD25⁻ accessory T cells. This subtype of CD4⁺CD25⁻CD69⁺LAG3⁺ T cells has been recognized as induced regulatory phenotype promoting anergy in activated T cells. Indeed, we observed that CBD treatment results in upregulation of EGR2 (a key T cell anergy inducer) mRNA transcription in stimulated T_MOG cells. This was accompanied by elevated levels of anergy promoting genes such as IL-10 (anti-inflammatory cytokine), STAT5 (regulatory factor), and LAG3 mRNAs, as well as of several enhancers of cell cycle arrest (such as Nfatc1, Casp4, Cdkn1a, and Icos). Moreover, CBD exposure leads to a decrease in STAT3 and to an increase in STAT5 phosphorylation in T_MOG cells, positive and negative regulators of Th17 activity, respectively. In parallel, we observed decreased levels of major histocompatibility complex class II (MHCII), CD25, and CD69 on CD19⁺ B cells following CBD treatment, showing diminished antigen presenting capabilities of B cells and reduction in their pro-inflammatory functions.

Conclusions

Our data suggests that CBD exerts its immunoregulatory effects via induction of CD4⁺CD25⁻CD69⁺LAG3⁺ cells in MOG35-55-activated APC/T_MOG co-cultures. This is accompanied by EGR2-dependent anergy of stimulated T_MOG cells as well as a switch in their intracellular STAT3/STAT5 activation balance leading to the previously observed decrease in Th17 activity.

The th17/treg immune balance in ulcerative colitis patients with two different chinese syndromes: dampness-heat in large intestine and spleen and kidney yang deficiency syndrome

Objective. To investigate the Th17/Treg immune balance in the ulcerative colitis (UC) patients with two Chinese syndrome: dampness-heat in large intestine (DHLI) and spleen and kidney Yang deficiency (SKYD). Methods. Ninety UC patients (45 were diagnosed with DHLI and 45 with SKYD syndrome) and 23 healthy people were recruited. The serumIL-17 and TGF-β1 levels of these participants were measured with ELISA; the expression of IL-17 and TGF-β 1 in colonic mucosa tissue was determined with immunohistochemistry and the percentage of Th17 and Treg in peripheral blood with flow cytometry. Results. The levels of IL-17 and Th17 were significantly higher in both DHLI and SKYD groups than in healthy control group and higher in DHLI than in SKYD group (P < 0.05). The levels of TGF-β1 and Treg were significantly lower in the two UC patients groups than in healthy control group; and lower in SKYD group than in DHLI group (P < 0.05). Conclusions. UC with DHLI syndrome could be characterized by the elevation of Th17 and IL-17 levels, which indicated an accentuation of inflammatory reaction; UC with SKYD syndrome could be characterized by the reduction of serum Treg and TGF-β1 levels, which represented a depression of immune tolerance.

Clinical blockade of PD1 and LAG3--potential mechanisms of action

Dysfunctional T cells can render the immune system unable to eliminate infections and cancer. Therapeutic targeting of the surface receptors that inhibit T cell function has begun to show remarkable success in clinical trials. In this Review, we discuss the potential mechanisms of action of the clinical agents that target two of these receptors, programmed cell death protein 1 (PD1) and lymphocyte activation gene 3 protein (LAG3). We also suggest correlative studies that may define the predominant mechanisms of action and identify predictive biomarkers.

Immunologic checkpoint blockade in lung cancer

Despite the availability of radiotherapy, cytotoxic agents, and targeted agents, a high unmet medical need remains for novel therapies that improve treatment outcomes in patients with lung cancer who are ineligible for surgical resection. Building upon the early promise shown with general immunostimulatory agents, immuno-oncology is at the forefront of research in this field, with several novel agents currently under investigation. In particular, agents targeting immune checkpoints, such as the cytotoxic T-lymphocyte antigen-4 (CTLA-4) receptor and programmed death-1 (PD-1) receptor, have shown in early clinical trials potential for improving tumor responses and survival in patients with non-small cell lung cancer (NSCLC). Here, we examine the rationale for targeting immune checkpoints in lung cancer and review the clinical data from studies with immune checkpoint inhibitors currently in development. The challenges associated with optimizing treatment with these agents in lung cancer also are discussed.

Exploring the potential of immuno-oncology-based treatment for patients with non-small cell lung cancer

Immune evasion is recognized as a key strategy for cancer survival and progression. With increased understanding of immune escape mechanisms, the development of immunotherapies to restore anti-tumor immune responses has flourished. Immuno-oncology (I-O) agents targeting checkpoints in the immune regulation cascade currently form the mainstay of approaches of cancer immunotherapy. Since initial success in melanoma, evidence for the notable effects of the I-O modality has been expanding, with numerous clinical studies underway or completed in a variety of solid tumors, including non-small cell lung cancer. This review highlights the rationale and potential role of immunotherapy in non-small cell lung cancer management, with a focus on immune checkpoint inhibitors. We also discuss the potential for I-O-based combination therapy.

Gene expression profiling of the response to interferon beta in Epstein-Barr-transformed and primary B cells of patients with multiple sclerosis

The effects of interferon-beta (IFN-β), one of the key immunotherapies used in multiple sclerosis (MS), on peripheral blood leukocytes and T cells have been extensively studied. B cells are a less abundant leukocyte type, and accordingly less is known about the B cell-specific response to IFN-β. To identify gene expression changes and pathways induced by IFN-β in B cells, we studied the in vitro response of human Epstein Barr-transformed B cells (lymphoblast cell lines-LCLs), and validated our results in primary B cells. LCLs were derived from an MS patient repository. Whole genome expression analysis identified 115 genes that were more than two-fold differentially up-regulated following IFN-β exposure, with over 50 previously unrecognized as IFN-β response genes. Pathways analysis demonstrated that IFN-β affected LCLs in a similar manner to other cell types by activating known IFN-β canonical pathways. Additionally, IFN-β increased the expression of innate immune response genes, while down-regulating many B cell receptor pathway genes and genes involved in adaptive immune responses. Novel response genes identified herein, NEXN, DDX60L, IGFBP4, and HAPLN3, B cell receptor pathway genes, CD79B and SYK, and lymphocyte activation genes, LAG3 and IL27RA, were validated as IFN-β response genes in primary B cells. In this study new IFN-β response genes were identified in B cells, with possible implications to B cell-specific functions. The study's results emphasize the applicability of LCLs for studies of human B cell drug response. The usage of LCLs from patient-based repositories may facilitate future studies of drug response in MS and other immune-mediated disorders with a B cell component.

The changing immune system in sepsis: is individualized immuno-modulatory therapy the answer?

Sepsis remains the leading cause of death in most intensive care units. Advances in understanding the immune response to sepsis provide the opportunity to develop more effective therapies. The immune response in sepsis can be characterized by a cytokine-mediated hyper-inflammatory phase, which most patients survive, and a subsequent immune-suppressive phase. Patients fail to eradicate invading pathogens and are susceptible to opportunistic organisms in the hypo-inflammatory phase. Many mechanisms are responsible for sepsis-induced immuno-suppression, including apoptotic depletion of immune cells, increased T regulatory and myeloid-derived suppressor cells, and cellular exhaustion. Currently in clinical trial for sepsis are granulocyte macrophage colony stimulating factor and interferon gamma, immune-therapeutic agents that boost patient immunity. Immuno-adjuvants with promise in clinically relevant animal models of sepsis include anti-programmed cell death-1 and interleukin-7. The future of immune therapy in sepsis will necessitate identification of the immunologic phase using clinical and laboratory parameters as well as biomarkers of innate and adaptive immunity.

Rational combinations of immunotherapeutics that target discrete pathways

An effective anti-tumor immune response requires the coordinated action of the innate and adaptive phases of the immune system. Critical processes include the activation of dendritic cells to present antigens, produce cytokines including type I interferons, and express multiple costimulatory ligands; induction of a productive T cell response within lymph nodes; migration of activated T cells to the tumor microenvironment in response to chemokines and homing receptor expression; and having effector T cells gain access to antigen-expressing tumor cells and maintain sufficient functionality to destroy them. However, tumors can become adept at escaping the immune response, developing multiple mechanisms to disrupt key processes. In general, tumors can be assigned into two different, major groups depending on whether the tumor there is an 'inflamed' or 'non-inflamed' tumor microenvironment. Improvements in our understanding of the interactions between the immune system and cancer have resulted in the development of various strategies to improve the immune-mediated control of tumors in both sub-groups. Categories of major immunotherapeutic intervention include methods to increase the frequency of tumor antigen-specific effector T cells in the circulation, strategies to block or uncouple a range of immune suppressive mechanisms within the tumor microenvironment, and tactics to induce de novo immune inflammation within the tumor microenvironment. The latter may be particularly important for eliciting immune recognition of non-inflamed tumor phenotypes. The premise put forth in this review is that synergistic therapeutic effects in vivo may be derived from combination therapies taken from distinct "bins" based on these mechanisms of action. Early data in both preclinical and some clinical studies provide support for this model. We also suggest that optimal application of these combinations may be aided by appropriate patient selection based on predictive biomarkers.

Novel antibodies targeting immune regulatory checkpoints for cancer therapy

Cancers must evade or suppress the immune system in order to develop. Better understanding of the molecular regulation governing tumour detection and effective activation of the immune system (so called immune regulatory checkpoints) has provided new targets for cancer immunotherapy. Therapeutic monoclonal antibodies against these targets are currently undergoing clinical evaluation with more in pre-clinical development; buoyed by the recent licence approval of the anti-CTLA-4 antibody, ipilumumab, for use in melanoma. This article will review the current status of the various antibodies and target molecules being investigated.

Molecular mechanisms of T cell co-stimulation and co-inhibition

Co-stimulatory and co-inhibitory receptors have a pivotal role in T cell biology, as they determine the functional outcome of T cell receptor (TCR) signalling. The classic definition of T cell co-stimulation continues to evolve through the identification of new co-stimulatory and co-inhibitory receptors, the biochemical characterization of their downstream signalling events and the delineation of their immunological functions. Notably, it has been recently appreciated that co-stimulatory and co-inhibitory receptors display great diversity in expression, structure and function, and that their functions are largely context dependent. Here, we focus on some of these emerging concepts and review the mechanisms through which T cell activation, differentiation and function is controlled by co-stimulatory and co-inhibitory receptors.

Coinhibitory molecules in cancer biology and therapy

The adaptive immune response is controlled by checkpoints represented by coinhibitory molecules, which are crucial for maintaining self-tolerance and minimizing collateral tissue damage under physiological conditions. A growing body of preclinical evidence supports the hypothesis that unleashing this immunological break might be therapeutically beneficial in the fight against cancer, as it would elicit an effective antitumor immune response. Remarkably, recent clinical trials have demonstrated that this novel strategy can be highly effective in the treatment of patients with cancer, as shown by the paradigmatic case of ipilimumab (a monoclonal antibody blocking the coinhibitory molecule cytotoxic T lymphocyte associated antigen-4 [CTLA4]) that is opening a new era in the therapeutic approach to a chemoresistant tumor such as cutaneous melanoma. In this review we summarize the biology of coinhibitory molecules, overview the experimental and clinical attempts to interfere with these immune checkpoints to treat cancer and critically discuss the challenges posed by such a promising antitumor modality.

Advances in targeting cell surface signalling molecules for immune modulation

The past decade has witnessed a surge in the development of immunomodulatory approaches to combat a broad range of human diseases, including cancer, viral infections, autoimmunity and inflammation as well as in the prevention of transplant rejection. Immunomodulatory approaches mostly involve the use of monoclonal antibodies or recombinant fusion proteins that target cell surface signalling molecules on immune cells to drive immune responses towards the desired direction. Advances in our understanding of the human immune system, along with valuable lessons learned from the first generation of therapeutic biologics, are aiding the design of the next generation of immunomodulatory biologics with better therapeutic efficacy, minimized adverse effects and long-lasting clinical benefit. The recent encouraging results from antibodies targeting programmed cell death protein 1 (PD1) and B7 homolog 1 (B7H1; also known as PDL1) for the treatment of various advanced human cancers show that immunomodulatory therapy has come of age.

Advances in the development of cancer immunotherapies

Manipulating the immune system in order to induce clinically relevant responses against cancer is a longstanding goal. Interventions to enhance tumor-specific immunity through vaccination, sustaining effector T cell activation, or increasing the numbers of tumor-specific T cells using ex vivo expansion, have all resulted in clinical successes. Here, we examine recent clinical advances and major ongoing studies in the field of cancer immunotherapy. Single agents have so far benefited a limited proportion of patients, and future studies combining different types of immunotherapies and other therapeutic modalities, such as drugs against specific signaling pathways driving cancer cell growth, are needed to pave the way for the development of effective anticancer treatments causing durable responses.