Increased IFN-γ Production Research Articles

B Cells Control Mucosal-Associated Invariant T Cell Responses to Salmonella enterica Serovar Typhi Infection Through the CD85j HLA-G Receptor.

Mucosal-associated invariant T (MAIT) cells are an innate-like population of T cells that display a TCR Vα7.2+ CD161+ phenotype and are restricted by the nonclassical MHC-related molecule 1 (MR1). Although B cells control MAIT cell development and function, little is known about the mechanisms underlying their interaction(s). Here, we report, for the first time, that during Salmonella enterica serovar Typhi (S. Typhi) infection, HLA-G expression on B cells downregulates IFN-γ production by MAIT cells. In contrast, blocking HLA-G expression on S. Typhi-infected B cells increases IFN-γ production by MAIT cells. After interacting with MAIT cells, kinetic studies show that B cells upregulate HLA-G expression and downregulate the inhibitory HLA-G receptor CD85j on MAIT cells resulting in their loss. These results provide a new role for HLA-G as a negative feedback loop by which B cells control MAIT cell responses to antigens.

PD-1 Blockade Restores the Proliferation of Peripheral Blood Lymphocyte and Inhibits Lymphocyte Apoptosis in a BALB/c Mouse Model of CP BVDV Acute Infection.

Acute infection of bovine viral diarrhea virus (BVDV) is associated with immune dysfunction and can cause peripheral blood lymphopenia and lymphocyte apoptosis. Our previous study has confirmed that programmed death-1 (PD-1) blockade inhibits peripheral blood lymphocytes (PBL) apoptosis and restores proliferation and anti-viral immune functions of lymphocytes after BVDV infection in vitro. However, the situation in vivo remains to be further studied and confirmed. Therefore, in this study, we established a BALB/c mouse model of acute BVDV infection with cytopathic (CP) BVDV (strain NADL) and non-cytopathic (NCP) BVDV (strain NY-1). Then, we examined the mRNA and protein levels of PD-1 and programmed death-ligand 1 (PD-L1) in peripheral blood mononuclear cells (PBMC) from BVDV-infected mice and analyzed the effects of PD-1 blockade on the proportions of CD3+, CD4+, and CD8+ T cell subsets, the apoptosis and proliferation of PBL, and the production of IL-2 and IFN-γ. We found that leukopenia, lymphocytopenia, and thrombocytopenia were developed in both CP and NCP BVDV-infected mice at day 7 of post-infection. The mRNA and protein expression of PD-1 and PD-L1 were significantly upregulated in CP and NCP BVDV-infected mice. Moreover, PD-1/PD-L1 upregulation was accompanied by leukopenia and lymphopenia. Additionally, PD-1 blockade inhibited PBL apoptosis and virus replication, restored the proportions of CD3+, CD4+, and CD8+ T cell subsets, and increased IFN-γ production and p-ERK expression in BVDV-infected mice. However, blocking PD-1 did not significantly affect PBL proliferation and IL-2 production in NCP BVDV-infected mice. Our findings further confirmed the immunomodulatory role of PD-1 in peripheral blood lymphocytopenia in vivo and provided a scientific basis for exploring the molecular mechanism of immune dysfunction caused by acute BVDV infection.

Non-autophagy Role of Atg5 and NBR1 in Unconventional Secretion of IL-12 Prevents Gut Dysbiosis and Inflammation.

Intestinal myeloid cells play a critical role in balancing intestinal homeostasis and inflammation. Here, we report that expression of the autophagy-related 5 [Atg5] protein in myeloid cells prevents dysbiosis and excessive intestinal inflammation by limiting IL-12 production. Mice with a selective genetic deletion of Atg5 in myeloid cells [Atg5ΔMye] showed signs of dysbiosis preceding colitis, and exhibited severe intestinal inflammation upon colitis induction that was characterised by increased IFNγ production. The exacerbated colitis was linked to excess IL-12 secretion from Atg5-deficient myeloid cells and gut dysbiosis. Restoration of the intestinal microbiota or genetic deletion of IL-12 in Atg5ΔMye mice attenuated the intestinal inflammation in Atg5ΔMye mice. Additionally, Atg5 functions to limit IL-12 secretion through modulation of late endosome [LE] acidity. Last, the autophagy cargo receptor NBR1, which accumulates in Atg5-deficient cells, played a role by delivering IL-12 to LE. In summary, Atg5 expression in intestinal myeloid cells acts as an anti-inflammatory brake to regulate IL-12, thus preventing dysbiosis and uncontrolled IFNγ-driven intestinal inflammation.

IRF8 Impacts Self-Renewal of Hematopoietic Stem Cells by Regulating TLR9 Signaling Pathway of Innate Immune Cells.

IRF8 is a key regulator of innate immunity receptor signaling and plays diverse functions in the development of hematopoietic cells. The effects of IRF8 on hematopoietic stem cells (HSCs) are still unknown. Here, it is demonstrated that IRF8 deficiency results in a decreased number of long‐term HSCs (LT‐HSCs) in mice. However, the repopulation capacity of individual HSCs is significantly increased. Transcriptomic analysis shows that IFN‐γ and IFN‐α signaling is downregulated in IRF8‐deficient HSCs, while their response to proinflammatory cytokines is unchanged ex vivo. Further tests show that Irf8 −/− HSCs can not respond to CpG, an agonist of Toll‐like receptor 9 (TLR9) in mice, while long‐term CpG stimulation increases wild‐type HSC abundance and decreases their bone marrow colony‐forming capacity. Mechanistically, as the primary producer of proinflammatory cytokines in response to CpG stimulation, dendritic cells has a blocked TLR9 signaling due to developmental defect in Irf8 −/− mice. Macrophages remain functionally intact but severely reduce in Irf8 −/− mice. In NK cells, IRF8 directly regulates the expression of Tlr9 and its deficiency leads to no increased IFNγ production upon CpG stimulation. These results indicate that IRF8 regulates HSCs, at least in part, through controlling TLR9 signaling in diverse innate immune cells.

Oophorectomy significantly impacts response to immune therapy regimens in preclinical models of ovarian cancer

<h3>Objectives:</h3> We have previously shown that PARP inhibition (PARPi) synergizes with CTLA-4 immune checkpoint blockade, improving survival in syngeneic high grade serous ovarian cancer models. This combination is currently being tested in clinical trials (NCT02571725 and NCT04034927). In the same models, no therapeutic benefit was seen when PARPi was combined with PD-1 blockade. We attribute the selective synergy of CTLA-4 antibody with PARPi to changes in the ovarian tumor microenvironment (TME). An increase in IFNγ production as a result of treatment with PARPi/CTLA-4 antibody was a predictor of improved survival. These results illustrate the importance of establishing cancer models that accurately represent conditions in the ovarian TME. Most preclinical studies are conducted in mice with intact ovarian function, while women with ovarian cancer are postmenopausal or undergo oophorectomy as part of their treatment. Immunotherapy clinical trials have observed differences in outcomes based on sex. Emerging evidence shows that estrogen affects immune function. Therefore, we tested the impact of oophorectomy on the immune microenvironment and its effects on disease outcome. <h3>Methods:</h3> Oophorectomy was performed on five-week-old female FVB mice that were subsequently injected intraperitoneally with BR5-Akt high grade serous ovarian cancer cells. Three days after tumor challenge, mice received a PARP inhibitor (ABT-888) and immune checkpoint inhibitor (anti-PD1 antibody or CTLA-4 antibody). Mice that had undergone laparotomy without oophorectomy (sham) or no surgery served as controls. On day 24, peritoneal T cells were analyzed by flow cytometry for phenotype and IFNγ production. Tumor burden was measured by non-invasive bioluminescence imaging. <h3>Results:</h3> Estrogen depletion through oophorectomy affects T cell phenotypes, increasing the proportion of central memory CD8 T cells compared to controls in the anti-PD1 combination treatment group. In the same group, estrogen depletion is associated with an increase in IFNγ production by both CD4 and CD8 T cells. These changes were associated with a decrease in tumor burden. The same effects were not seen in mice treated with combination PARPi and CTLA-4 antibody. <h3>Conclusions:</h3> The data presented here confirm that estrogen impacts tumor associated lymphocyte phenotype and function, affecting parameters that are associated with improved disease outcomes in combination of PARPi and immune checkpoint blockade. With knowledge of the significant impact of estrogen on anti-tumor immune function, we can develop pre-clinical models that accurately reflect the immune microenvironment established in ovarian cancer. This will facilitate the development of highly effective immunotherapeutic regimens that will enhance their translational potential and ultimately improve patient outcomes.

Immune Checkpoint Blockade Enhances Mutated Calreticulin-Induced T Cell Immunity in Myeloproliferative Neoplasms

▪Somatic mutations in the calreticulin (CALR) gene are key drivers of cellular transformation in myeloproliferative neoplasms (MPN) and are the second most common driver mutations in essential thrombocythemia (ET) and myelofibrosis (MF) patients. Each CALR mutation leads to a shift in the reading frame resulting in the formation of an altered protein with an identical 36-amino acid sequence in the C-terminus. We hypothesized that the recurrence and uniformity of the novel sequence would provide the mutated CALR an attractive candidate as a MPN-specific tumor antigen that might elicit anti-tumor immune responses. Therefore, we investigated the immunogenicity of the altered CALR by employing in silico peptide binding prediction algorithms to interrogate the binding affinities of mutated CALR peptides to human leukocyte antigens (HLA). These analyses indicated that the mutated epitopes can bind to class I and II HLA alleles with high affinity supporting the hypothesis that mutant CALR could be immunogenic in vivo . We then tested the immunogenicity of the overlapping peptides spanning the mutated region in vitro by utilizing intracellular staining (ICS) and Enzyme-Linked ImmunoSPOT (ELISPOT) assays. Naïve T cells derived from the peripheral blood mononuclear cells (PBMNCs) isolated from healthy donors displayed effector functions after priming with the mutated peptides but not with the corresponding wild type peptides . Incubation withthe mutated CALR peptides induced T cells proliferation, upregulation of CD137 (4-1BB) and production of interferon (IFN)-γ and tumor necrosis factor (TNF)-α. Moreover, as suggested by in silico peptide-HLA binding predictions, both CD8+ and CD4+ T cell precursors displayed increased IFN-γ production in response to stimulation with mutated CALR peptides. There was an overall 4±3-fold increase in IFN-γ production by CD4+ T cells and a 2.5±0.5-fold increase by CD8+ T cells after stimulation with mutated peptides as compared to control self-antigens (n = 14 healthy donors out of which 11 showed CD4+ and 5 showed CD8+ T cell responses). These results demonstrate that mutated CALR elicits T cell responses in vitro supporting its potential immunogenic functions in vivo .We next investigated the presence of mutant CALR-specific T cell immunity in MPN patients with CALR mutations. PBMNCs from a total of 18 CALR-mutated MPN patients with ET (7), MF (5) or MF arising from ET (6) were evaluated. MPN T cells were then stimulated with the pooled mutant CALR peptides and T cell responses were assessed by ELISPOT. Out of 18 patients, increased IFN-γ production upon stimulation was observed in only 2 patients (one with ET and one with ET-MF). The less than robust MPN T cell responses suggested that immune suppressive mechanisms might be operating. To this end, we evaluated the expression of cell surface inhibitory receptors, programmed cell death (PD)-1 and the cytotoxic T-lymphocyte-associated antigen (CTLA)-4, by T cells from MPN patients. Both CD8+ and CD4+ T cells from MPN patients exhibited increased levels of PD-1 and CTLA-4 when compared to the healthy controls (HC). For instance, 9.3±8.2% of MPN patients CD4+ T cells expressed PD-1 (n = 12) as compared to 2.5±1.7% of HC CD4+ T cells (n=10) (p value = 0.0482). Similarly, there were twice as many PD-1 expressing CD8+ T cells in MPN patients as compared to HC. We next assessed MPN T cell responses against mutated peptides in the presence of neutralizing PD-1 or CTLA-4 antibodies. PD-1 inhibition restored T cell immunity in cultures derived from 3 MPN patients and CTLA-4 inhibition restored response in one patient (n=16). Of note, following the PD-1 or CTLA-4 inhibition, the number of IFN-γ producing cells and the amount of IFN-γ produced on a per-cell-basis increased upon stimulation with mutant-CALR peptides as compared to control peptides. These results indicate that the limited MPN T cell responses to CALR mutated peptides were due to T cell exhaustion caused, at least in part, by activation of the PD-1/CTLA-4 pathway.In summary, our studies establish mutated CALR as a MPN-specific tumor antigen thereby providing a rationale for the development of immunotherapies targeting mutated CALR in patients. Moreover, our data indicate that immune checkpoint signaling might be responsible for T cell exhaustion in some MPN patients thereby supporting the use of checkpoint blockade inhibitors for treatment of these patients. DisclosuresMascarenhas:Incyte: Other: Clinical Trial Steering Committee , Research Funding; CTI Biopharma: Research Funding; Janssen: Research Funding; Merck: Research Funding; Novartis: Other: DSMB member , Research Funding; Promedior: Research Funding. Bhardwaj:Merck & Co., Inc.: Membership on an entity's Board of Directors or advisory committees; Dendreon Corporation: Membership on an entity's Board of Directors or advisory committees; Dynavax Technologies Corporation: Consultancy; Crucell: Patents & Royalties; Neostem, Inc.: Patents & Royalties.

Synergistic Activation of Bovine CD4+ T Cells by Neutrophils and IL-12.

CD4+ T cell activation requires inflammatory cytokines to provide a third signal (3SI), such as interleukin-12 (IL-12). We recently reported that bovine neutrophils can enhance the activation of bovine CD4+ T cells. To explore the interactions between neutrophils and third signal cytokines in bovine CD4+ T cell activation, naïve CD4+ T cells were isolated from cattle lymph nodes and stimulated for 3.5 days with anti-bovine CD3 (first signal; 1SI), anti-bovine CD28 (second signal; 2SI), and recombinant human IL-12 (3SI) in the presence or absence of neutrophils harvested from the same animals. Indeed, the strongest activation was achieved in the presence of all three signals, as demonstrated by CD25 upregulation, IFNγ production in CD4+ T cells, and secretion of IFNγ and IL-2 in cell supernatants. More importantly, 1SI plus neutrophils led to enhanced CD25 expression that was further increased by IL-12, suggesting synergistic action by IL-12 and neutrophils. Consistently, neutrophils significantly increased IFNγ production in 1SI plus IL-12-stimulated CD4+ T cells. Our data suggest the synergy of neutrophils and IL-12 as a novel regulator on bovine CD4+ T cell activation in addition to three signals. This knowledge could assist the development of immune interventions for the control of infectious diseases in cattle.

Checkpoint blockade accelerates a novel switch from an NKT-driven TNFα response toward a T cell driven IFN-γ response within the tumor microenvironment

BackgroundThe temporal response to checkpoint blockade (CB) is incompletely understood. Here, we profiled the tumor infiltrating lymphocyte (TIL) landscape in response to combination checkpoint blockade at two distinct timepoints of...

The pandemic matrix gene is associated with increased pro-inflammatory immune responses during influenza virus infection

Abstract The 2009 H1N1 influenza pandemic (pdmH1N1) arose from multiple genetic reassortment events between three swine influenza A virus (swIAV) lineages and became established as a seasonal H1N1 human influenza virus. Through reverse-zoonotic events, the pdmH1N1 strain contributed gene segments to endemic swIAVs and the pandemic matrix gene (pdmM) completely replaced the classical swine matrix gene (swM), suggesting a fitness benefit. We assessed a panel of swIAVs in the BALB/c mouse model and demonstrated that swIAVs containing the pdmM gene caused increased morbidity, lung pathology, and mortality compared to swIAVs containing the swM gene. We hypothesized that swIAVs containing the pdmM gene induce dysregulation of the innate response, causing increased disease. To test this, mice were infected with swIAVs containing either the pdmM or the swM gene segment, and immune cell infiltrates, cytokine production, and histopathology were assessed. We found that pdmM viruses elicited increased cellular infiltration, NK cell activation and increased IFNγ production in bronchial alveolar lavage (BAL) fluid compared to mice infected with swM viruses. We also detected increased numbers of infiltrating macrophages, neutrophils, DCs, and eosinophils, as well as increased proinflammatory cytokine production. Additionally, elevated myeloperoxidase content was detected in BAL fluid, suggesting increased neutrophil activation. Finally, infection with pdmM viruses resulted in greater histologic lesion scores compared to swM viruses. We conclude the pdmM gene elicits increased innate immune responses, causing greater disease in a mouse model of infection. Future studies will identify determinants of increased disease severity.

Two sequential activation modules control the differentiation of protective T helper-1 (Th1) cells

Interferon-γ (IFN-γ)-producing CD4+ T helper-1 (Th1) cells are critical for protection from microbes that infect the phagosomes of myeloid cells. Current understanding of Th1 cell differentiation is based largely on reductionist cell culture experiments. We assessed Th1 cell generation invivo by studying antigen-specific CD4+ Tcells during infection with the phagosomal pathogen Salmonella enterica (Se), or influenza A virus (IAV), for which CD4+ Tcells are less important. Both microbes induced T follicular helper (Tfh) and interleukin-12 (IL-12)-independent Th1 cells. During Se infection, however, the Th1 cells subsequently outgrew the Tfh cells via an IL-12-dependent process and formed subsets with increased IFN-γ production, ZEB2-transcription factor-dependent cytotoxicity, and capacity to control Se infection. Our results indicate that many infections induce a module that generates Tfh and poorly differentiated Th1 cells, which is followed in phagosomal infections by an IL-12-dependent Th1 cell amplification module that is critical for pathogen control.

Plasmodium chabaudi Infection Alters Intestinal Morphology and Mucosal Innate Immunity in Moderately Malnourished Mice.

Plasmodium falciparum is a protozoan parasite which causes malarial disease in humans. Infections commonly occur in sub-Saharan Africa, a region with high rates of inadequate nutrient consumption resulting in malnutrition. The complex relationship between malaria and malnutrition and their effects on gut immunity and physiology are poorly understood. Here, we investigated the effect of malaria infection in the guts of moderately malnourished mice. We utilized a well-established low protein diet that is deficient in zinc and iron to induce moderate malnutrition and investigated mucosal tissue phenotype, permeability, and innate immune response in the gut. We observed that the infected moderately malnourished mice had lower parasite burden at the peak of infection, but damaged mucosal epithelial cells and high levels of FITC-Dextran concentration in the blood serum, indicating increased intestinal permeability. The small intestine in the moderately malnourished mice were also shorter after infection with malaria. This was accompanied with lower numbers of CD11b+ macrophages, CD11b+CD11c+ myeloid cells, and CD11c+ dendritic cells in large intestine. Despite the lower number of innate immune cells, macrophages in the moderately malnourished mice were highly activated as determined by MHCII expression and increased IFNγ production in the small intestine. Thus, our data suggest that malaria infection may exacerbate some of the abnormalities in the gut induced by moderate malnutrition.

Semaphorin 3E Promotes Susceptibility to Leishmania major Infection in Mice by Suppressing CD4+ Th1 Cell Response.

Protective immunity to cutaneous leishmaniasis is mediated by IFN-γ-secreting CD4+ Th1 cells. IFN-γ binds to its receptor on Leishmania-infected macrophages, resulting in their activation, production of NO, and subsequent destruction of parasites. This study investigated the role of Semaphorin 3E (Sema3E) in host immunity to Leishmania major infection in mice. We observed a significant increase in Sema3E expression at the infection site at different timepoints following L. major infection. Sema3E-deficient (Sema3E knockout [KO]) mice were highly resistant to L. major infection, as evidenced by significantly (p < 0.05-0.01) reduced lesion sizes and lower parasite burdens at different times postinfection when compared with their infected wild-type counterpart mice. The enhanced resistance of Sema3E KO mice was associated with significantly (p < 0.05) increased IFN-γ production by CD4+ T cells. CD11c+ cells from Sema3E KO mice displayed increased expression of costimulatory molecules and IL-12p40 production following L. major infection and were more efficient at inducing the differentiation of Leishmania-specific CD4+ T cells to Th1 cells than their wild-type counterpart cells. Furthermore, purified CD4+ T cells from Sema3E KO mice showed increased propensity to differentiate into Th1 cells in vitro, and this was significantly inhibited by the addition of recombinant Sema3E in vitro. These findings collectively show that Sema3E is a negative regulator of protective CD4+ Th1 immunity in mice infected with L. major and suggest that its neutralization may be a potential therapeutic option for treating individuals suffering from cutaneous leishmaniasis.

Synergistic effect of GRA7 and profilin proteins in vaccination against chronic Toxoplasma gondii infection

Toxoplasmosis is a zoonotic disease with worldwide prevalence in humans and warm-blooded animal populations. In livestock Toxoplasma gondii is the causal agent of significant economic losses since it can cause abortions in goats and sheep. It is estimated that one third of the world population is infected. Although there are effective therapies for acute infection, these are sometimes poorly tolerated, teratogenic, and have a long administration time. Considering the deficiencies that exist related to the prevention and treatment of toxoplasmosis, the development of a safe and effective vaccine would be extremely valuable in fighting against this infection. In the present work, we characterize for the first time the adjuvant and immunogenic potential of a recombinant profilin protein (rTgPF), in a vaccine formulation alone or in combination with the well-known GRA7 antigen candidate in a murine toxoplasmosis model. Since TgPF acts as a ligand for TLR11 and 12 inducing innate immune responses that promote type 1 adaptive responses, we first study the capacity of the mix rGRA7 + rTgPF to initiate an immune response by evaluating dendritic cell activation. Both rTgPF and rGRA7 induces activation of mouse BMDCs more efficiently than the single proteins, evidenced by increased expression of CD80 and CD86 co-stimulatory proteins and secretion of IL-6, IL-10 and IL-12 cytokines after in vitro stimulation. The sum of the effects of rGRA7 and rTgPF on BMDCs maturation led us to assay them in a vaccination protocol. BALB/c mice vaccinated with this mix elicited a Th1-biased immunity via the induction of lymphocyte proliferation, activation of CD4+T cells and increased IFN-γ production that resulted in enhanced protection against chronic Toxoplama gondii infection. Profilin per se induce only cellular immunity but augments the effect of rGRA7 immune responses when used together, thus allowing us to postulate rTgPF as a potential adjuvant in a protein vaccine.

Modulation of the human immune status by spinal thermal massage: a non-randomized controlled study

Thermal and massage therapies have long been used to control pain. Although spinal thermal massage (STM) has been used worldwide, its effectiveness has not been proven in a controlled clinical study. We here conducted a non-randomized controlled trial to assess the pain-relieving and immunomodulatory effects of STM in old-aged patients experiencing pain or disability. The experimental group was treated with STM five times a week for 8 weeks and rehabilitative regular care (RRC). The control group was treated with only RRC. Pain and immunological parameters were tested before treatment and after 4 and 8 weeks of treatment. The scores of three pain parameters were lowered by STM, and the differences between the groups were statistically significant at the two time points (p &lt; 0.01). Quality of life determined using the 3-level EuroQol five-dimensional questionnaire scores was significantly higher in patients in the experimental group than those in the control group. Effect sizes (ES) were in the range of medium to large in the pain-related measures (0.54–1.22). The total leukocyte counts and the proportions of lymphocytes and subsets were not significantly different between the groups, whereas the proportions of monocytes and natural killer (NK) cells were higher in the experimental group than in the control group after 8 weeks (p &lt; 0.05). The production of interleukin (IL)-4 and interferon γ in T cells was not significantly different between the groups, whereas the production of IL-2 was high in the control group. However, there was a significant increase in IFN-γ production by NK cells in the experimental group (at 4 weeks, p &lt; 0.05). ES were medium in the immunological measures (0.53–0.68). No significant difference was observed in the production of proinflammatory cytokines, IL-1β, tumor necrosis factor α, or IL-6 between the groups. In conclusion, STM treatment has a positive effect on subjective pain and quality of life. It also enhanced NK cell proportion and activity, suggesting that STM may be beneficial in the prevention of viral diseases and cancer in old-aged people.

Evaluation of immunological role of Interferon gamma, Interleukin-10 and CD4+ T lymphocytes in pediatric patients with sickle cell disease

Sickle cell disease (SCD) is a chronic inflammatory disease associated with increased levels of multiple cytokines as interferon gamma (IFN-γ) during vaso-occlusive (VOC) crisis and steady state. Therefore, we aimed to explore theimmunological role of serum IFN-γ, interleukin-10 (IL-10) and CD4+ T lymphocytes in children with SCD at steady state and VOC. This study was conducted on 30 children with SCD (15 at steady state and 15 in VOC) and 30 healthy children as controls. Detailed history, complete physical, clinical examination and laboratory investigations as: complete blood count, serum ferritin, IFN-γ, IL-10 and CD4+ T lymphocytes for all patients were recorded. Results: Significant increase in serum IFN-γ in patients with SCD during VOC compared with patients at steady state and controls (P<0.001). Significant increase in serum IL-10 in patients with SCD at steady state compared with those during VOC and controls (P=0.008 and P=0.04 respectively). CD4 +T lymphocyte decreased in patients with SCD during VOC compared with those at steady state and controls (P<0.001). There was a significant positive correlation between serum IFN-ɣ and number of crisis per year (r=0.648, P=0.0001). Serum IFN-γ was increased in patients with history of frequent crisis per year (P=0.001) and decreased in patients under hydroxyurea therapy (P<0.001). IFN-γ was increased in SCD patients. Increased IFN-γ production in SCD suggesting that functionally activated natural killer cells reflecting a host immunological mechanism leading to antigen antibody activation in SCD. Serum IL-10 increased in SCD patients at steady state. CD4 +T lymphocyte decreased in patients during VOC.

Experimental Nanovaccine Offers Protection Against Repeat Exposures to Trypanosoma cruzi Through Activation of Polyfunctional T Cell Response.

A parasitic protozoan Trypanosoma cruzi (T. cruzi) is the etiologic agent of Chagas disease. Previously, we have identified T. cruzi antigens TcG2 and TcG4 as potential vaccine candidates, cloned in eukaryotic expression vector pCDNA3.1 (referred as p2/4) and tested their ability to elicit protection from T. cruzi infection. In the present study, we subcloned the two antigens in a nanoplasmid that is optimized for delivery, antigen expression, and regulatory compliance standards, and evaluated the nanovaccine (referred as nano2/4) for prophylactic protection against repeat T. cruzi infections. For this, C57BL/6 mice were immunized with two doses of p2/4 or nano2/4 at 21 days interval, challenged with T. cruzi 21 days after 2nd immunization, and euthanized at 10- and 21-days post-infection (pi) corresponding to parasite dissemination and replication phase, respectively. Some mice were re-challenged 21 days pi and monitored at 7 days after re-infection. Without the help of a vaccine, T. cruzi elicited delayed and sub-par T cell activation and low levels of effector molecules that failed to control tissue dissemination and replication of the parasite and provided no protection against repeat challenge infection. The nano2/4 was most effective in eliciting an early activation and production of IFN-γ by CD4+T effector/effector memory (TEM) cells and cytolytic perforin (PFN) and granzyme B (GZB) molecules by CD4+ and CD8+ TEM subsets at 10 days pi that was followed by robust expansion of CD4+ and CD8+ TEM and TCM cells with further increase in IFN-γ production at 21 days pi. Consequently, nano2/4-immunized mice exhibited potent control of parasite dissemination at 10 days pi, and tissue parasite burden and tissue inflammatory infiltrate and necrosis were barely detectable at 21 days pi. Furthermore, nano2/4-immunized mice responded to re-challenge infection with high levels of effector molecules production by CD4+ and CD8+ TEM subpopulations that offered even better control of tissue parasite burden than was observed after 1st infection. In comparison, non-vaccinated/infected mice exhibited clinical features of sickness and 59% mortality within 7 days after re-infection. In conclusion, we show that delivery of TcG2 and TcG4 in nanoplasmid offers excellent, protective T cell immunity against repeat T. cruzi infections.

Long-chain polyunsaturated omega-3 fatty acids reduce multiple myeloma exosome-mediated suppression of NK cell cytotoxicity.

Despite the advances in the treatment of multiple myeloma (MM), complete remission is usually challenging. The interactions between tumor and host cells, in which exosomes (EXs) play critical roles, have been shown to be among the major deteriorative tumor-promoting factors herein. Therefore, any endeavor to beneficially target these EX-mediated interactions could be of high importance. a) To investigate the effects of myeloma EXs on natural killer (NK) cell functions. b) To check whether treatment of myeloma cells with eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), two polyunsaturated omega-3 fatty acids with known anti-cancer effects, can modify myeloma EXs in terms of their effects on natural killer functions. L363 cells were treated with either EPA or DHA or left untreated and the released EXs (designated as E-EX, D-EX and C-EX, respectively) were used to treat NK cells for functional studies. Myeloma EXs (C-EXs) significantly reduced NK cytotoxicity against K562 cells (P ≤ 0.05), while the cytotoxicity suppression was significantly lower (P ≤ 0.05) in the (E-EX)- and (D-EX)-treated NK cells compared to the (C-EX)-treated cells. The expression of the activating NK receptor NKG2D and NK degranulation, after treatment with the EXs, were both altered following the same pattern. However, C-EXs could increase IFN-γ production in NK cells (P < 0.01), which was not significantly affected by EPA/DHA treatment. This indicates a dual effect of myeloma EXs on NK cells functions. Our observations showed that myeloma EXs have both suppressive and stimulatory effects on different NK functions. Treatment of myeloma cells with EPA/DHA can reduce the suppressive effects of myeloma EXs while maintaining their stimulatory effects. These findings, together with the previous findings on the anti-cancer effects of EPA/DHA, provide stronger evidence for the repositioning of the currently existing EPA/DHA supplements to be used in the treatment of MM as an adjuvant treatment. EXs released from L363 (myeloma) cells in their steady state increase IFN-γ production of NK cells, while reduce their cytotoxicity against the K562 cell line (right blue trace). EXs from L363 cells pre-treated with either EPA or DHA are weaker stimulators of IFN-γ production. These EXs also increase NK cytotoxicity and NKG2D expression (left brown trace) compared to the EXs obtained from untreated L363 cells. Based on these findings, myeloma EXs have both suppressive and stimulatory effects on different NK functions depending on the properties of their cells of origin, which can be exploited in the treatment of myeloma.

Increased Notch receptors induces CD8(+) T cell exhaustion in patients with prostate cancer

Objective: To investigate Notch receptor expression in CD8(+) T cells in patients with prostate cancer, and to assess the influence of Notch signaling pathway on the function of CD8(+)T cells inpatients with prostate cancer. Methods: Forty-five patients with prostate cancer, forty-one patients with nonbacterial prostatitis, and thirty healthy controls who were hospitalized or followed-up in Shanxi Provincial People's Hospital between November 2017 and June 2018 were enrolled. CD8(+)T cells were purified, and mRNA relative levels of Notch1-4 were semi-quantified by reverse transcriptional real-time PCR. CD8(+)T cells were stimulated with Notch signaling inhibitor γ-secretase inhibitor (GSI). mRNA relative levels of perforin, granzyme B, and FasL were semi-quantified by reverse transcriptional real-time PCR. Percentages of PD-1 and CTLA-4 positive cells were investigated by flow cytometry. Direct contact and indirect contact coculture systems were set up between CD8(+)T cells and prostate cancer cell line LAPC4 cells. The influence of Notch signaling inhibition to CD8(+)T cell cytotoxicitywas assessed by measuringtarget cell death and cytokine secretion. One-Way ANOVA, LSD-t test, and paired t test was used for comparison. Results: mRNA relative levels of Notch1~4 were elevated in CD8(+)T cells from prostate cancer patients when compared with those from healthy controls and nonbacterial prostatitis patients (all P<0.05). There was CD8(+)T cell exhaustion in prostate cancer patients, which presented as decreased mRNA relative levels of perforin, granzyme B, and FasL (all P<0.000 1), as well as increased percentage of PD-1(+)CD8(+) (19.3%±5.4%) and CTLA-4(+)CD8(+)(11.7%±3.9%) cells. CD8(+)T cells from prostate cancer patients induced LAPC cell death was downregulated in direct contact coculture system (28.8%±6.4% vs 37.2%±2.6%, P=0.015). IFN-γsecretion was also reduced ((61.7±10.6)ng/L vs (88.6±20.2)ng/L, P=0.003 2). Inhibition of Notch signaling by GSI increased mRNA of perforin, granzyme B, and FasL in CD8(+)T cells from prostate cancer patients (all P<0.01), while reduced percentage of PD-1(+)CD8(+)(12.6%±2.5% vs 17.4%±4.7%, P=0.005 9) and CTLA-4(+)CD8(+) (12.0%±1.0% vs 14.1%±3.1%, P=0.011)cells. Notch signaling inhibition promoted LAPC4 cell death (34.3%±7.2%, P=0.000 2) which induced by prostate cancer derived CD8(+)T cells, and increased IFN-γ production ((88.4±33.6)ng/L, P=0.008 3). Conclusion: Elevated Notch receptors induced CD8(+)T cells exhaustion in prostate cancer patients.

TLT2 Suppresses Th1 Response by Promoting IL-6 Production in Monocyte Through JAK/STAT3 Signal Pathway in Tuberculosis.

The function of triggering receptor expressed on myeloid cell-like transcript 2 (TLT2) has not been characterized and their role in pulmonary tuberculosis (TB) remains unclear. In this study, we found that surface TLT2 was up-regulated in human monocytes of patients with active TB compared to healthy subjects. In vitro, TLT2 expression was induced in human monocyte cell line THP-1 cells after bacillus Calmette-Guérin (BCG) or Mycobacterium tuberculosis (Mtb) H37Rv infection. Knockdown of TLT2 by siRNA transfection suppressed IL-6 expression, whereas over-expression of TLT2 increased IL-6 production in THP-1 cells infected by H37Rv. TLT2+CD14+ monocytes produced higher level of IL-6 compared to TLT2– subset in active TB patients. Western blot and immunocoprecipitation revealed that TLT2 interacted with kinase JAK1/JAK2/Tyk2 to enhance STAT3 phosphorylation. Moreover, we showed that tyrosine residues 297 and 315 of TLT2 cytoplasmic domain were involved in STAT3 activation. In monocyte/CD4+ T cell co-culture assay, blockage of TLT2 fusion protein facilitated IFN-γ production by CD4+ T cells. Plate count assay showed that monocyte-mediated bacterial killing was promoted by TLT2 fusion protein. In vivo treatment with TLT-2 fusion protein reduced IL-6 production by macrophage but increased IFN-γ production by CD4+ T cell in H37Rv and BCG infected mice. Furthermore, TLT2 fusion protein attenuated inflammation, and reduced bacterial load in lung of infected mice. Together, these findings demonstrate that TLT2 negatively regulates Th1 response against mycobacterial infection, which promotes IL-6 production through JAK/STAT3 signal pathway.

Abstract 3865: A translational immuno-oncology platform to model T cell activation and Tex recovery in the tumor microenvironment

Abstract The tumor microenvironment (TME) is a complex network, consisting of malignant tumor cells, stromal and immune cells, blood vessels, extracellular matrix and soluble factors. The immune system plays an important role in combating tumor growth, and multiple studies associate immune infiltrate with beneficial outcome. Various tractable immuno-oncology targets have been identified that influence the behavior of immune cells in the TME. These include Cytotoxic CD8+ T cells; which can directly kill tumour cells and produce pro-inflammatory cytokines such as IFNγ. However, CD8+ T cell activity and survival can be suppressed by the TME and chronic exposure leads to the generation of exhausted T cells (Tex) which have a lowered proliferative capacity and diminished capacity for pro-inflammatory cytokine production. Conversely, a regulatory subset of CD4+ T cells (Tregs) act to skew the TME towards immunosuppression. Here we describe human and murine models to assess both relative T cell subset activation and whether T cell exhaustion can be broken. Screening assays using T cell stimulants such as SEB or IL-2 can be utilised to select candidate therapeutics based on functional target engagement. SEB stimulation of PBMC reveals a robust additive effect on T cell activation by established and emerging checkpoint inhibitors. Use of more complicated flow based readouts allows the discrimination of immune subset responses. IL-2, a key lymphocyte activator, drives pSTAT5 expression with differing potency in PBMC subsets (regulatory T cells, conventional CD4 cells, CD8 T cells, NKT cells and NK cells). The ability to target specific subset activation could expand anti-tumour responses. Persistent antigenic stimulation, such as chronic exposure to the TME (MHC I restricted peptides), can lead to a CD8 Tex cell phenotype. Tex cell generation and reversal can be modelled using CEFT peptide pool and monitored via the expression of markers such as LAG-3, TIM-3, TOX and IFNγ. We show here that CD8 Tex cells respond positively to PD-1 blockade treatment, as seen by a restoration in cellular proliferation and increased IFNγ production. Therapeutic candidates identified through in vitro lead optimization can be assessed for their ability to activate T cells via a murine pharmacodynamic (PD) model. Transgenic OT-I CD8 T cells expressing TCR recognising OVA peptide (SIINFEKL) were transferred into syngeneic mice with SIINFEKL challenge in the presence of test therapeutic. Flow cytometry was used to determine OT-I T cell proliferation, activation and cytokine release. As seen in vitro, OT-I cell activation was increased by CPI treatment. We show here the powerful combination of using sophisticated in vitro and in vivo models to determine the effect of therapeutic intervention in an immuno-oncology context. Citation Format: Robert Nunan, Hannah Gill, Ilona Aylott, Michelle Yap, Tommaso Iannitti, Louise Harvey, Rhiannon Jenkinson. A translational immuno-oncology platform to model T cell activation and Tex recovery in the tumor microenvironment [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3865.