Inhibited IFN-γ Production Research Articles

Soluble PD-L1 shows no association to relapse and overall survival in early stage non-small cell lung cancer (NSCLC)

BackgroundCancer immune evasion is critical in non-small cell lung cancer (NSCLC) and has been targeted by immunotherapy. High soluble (s)PD-L1 is associated with reduced survival and treatment failure in advanced stages. Here we evaluated the effects of sPD-L1 on T cells, relapse free survival, and overall survival in early stage NSCLC. MethodsIn vitro T cell stimulation was performed in the presence of sPD-L1 to evaluate its immunomodulatory activity. Data from The Cancer Genome Atlas (TCGA) were investigated for PD-L1 splice variants and enzymes involved in proteolytic cleavage (i.e. ADAM10). Plasma from 74 NSCLC (stage IA-IIIB), as well as an additional 73 (control cohort) patients was collected prior to curative surgery. Thereafter sPD-L1 levels from an immunosorbent assay were correlated with patient outcome. ResultsIn vitro sPD-L1 inhibited IFN-γ production and proliferation of T cells and induced a terminal effector CD4 T cell subtype expressing CD27. Data from the TCGA demonstrated that elevated mRNA levels of ADAM10 is a negative predictor of outcome in NSCLC patients. To investigate the clinical relevance of these in vitro and TCGA findings, we quantified sPD-L1 in the plasma of early-stage NSCLC patients. In the first cohort we found significantly higher sPD-L1 levels in relapsing NSCLC patients, with a multivariate analysis revealing high sPD-L1 (>1000 pg/mL) as an independent predictor of survival. However, these findings could not be validated in two independent control cohorts. DiscussionAlthough in vitro and TCGA data support the suppressive effect of sPD-L1 we were unable to translate this in our clinical setting. These results may be due to the small patient number and their heterogeneity as well as the lack of a standardized sPD-L1 ELISA. Our inconclusive results regarding the value of sPD-L1 in early stage NSCLC warrant assay validation and further investigation in larger (neo-)adjuvant trials.

Circadian clock component PER2 negatively regulates CD4+ T cell IFN-γ production in ulcerative colitis

Period circadian clock 2 (PER2) is involved in the pathogenesis of various inflammatory and autoimmune diseases. However, there are gaps in our understanding of the role of PER2 in regulating CD4+ T cells beyond its time-keeping function in ulcerative colitis (UC) pathogenesis. Our findings revealed PER2 was predominantly expressed in CD4+ T cells, while it was significantly decreased in the inflamed mucosa and peripheral blood CD4+ T cells of UC patients compared with that in Crohn’s disease (CD) patients and healthy controls (HC). Notably, PER2 expression was significantly recovered in UC patients in remission (R-UC) compared to that in active UC patients (A-UC) but not in CD patients. It was negatively correlated with the Ulcerative Colitis Endoscopic Index of Severity (UCEIS), Crohn’s Disease Activity Index (CDAI), Simple Endoscopic Score for Crohn’s disease (SES-CD), and C-reactive protein (CRP), respectively. Overexpression of PER2 markedly inhibited IFN-γ production in UC CD4+ T cells. RNA-seq analysis showed that overexpression of PER2 could repress the expression of a disintegrin and metalloproteinase 12 (ADAM12), a costimulatory molecule that determines Th1 cell fate. Mechanistically, cleavage under targets and tagmentation (CUT&Tag) analysis revealed that PER2 down-regulated ADAM12 expression by reducing its binding activity, thereby suppressing IFN-γ production in UC CD4+ T cells. Additionally, our data further demonstrated that ADAM12 was upregulated in CD4+ T cells and inflamed mucosa of A-UC patients compared to HC. Our study reveals a critical role of PER2 in regulating CD4+ T cell differentiation and highlights its potential as a therapeutic target for UC treatment.

Effects of combined cytotoxic T-lymphocyte antigen 4 and programed death 1 ligand-receptor blockade on interferon-gamma production in bovine leukemia virus-infected cattle.

In chronic viral infections, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed death ligand 1 (PD-L1) significantly suppress immune responses. The CTLA-4 receptor abundance in regulatory T cells showed a positive association with viral load and a negative association with interferon-gamma (IFN-γ) production in bovine leukemia virus (BLV)-infected cattle. Blocking this receptor boosted IFN-γ production, recovering immune response against this illness. In human cancer patients, not everyone responded positively to non-immunotherapy using CTLA-4 receptor antibodies. The present study analyzed the synergistic effects of CTLA-4 and PD-L1 receptor blockade on IFN-γ production in BLV+ cattle in vitro. The genes for bovine CTLA-4 and PD-L1 were artificially produced. The amino acid sequences of the extracellular receptor domains were sourced from the National Center for Biotechnology Information PubMed database. The western blotting and liquid chromatography with tandem mass spectrometry (LC-MS/MS) techniques were employed for the characterization of recombinant CTLA-4 (rCTLA-4) and recombinant PD-L1 (rPD-L1) proteins. The immunoinhibitory effects of recombinant proteins in Staphylococcus enterotoxin B (SEB)-stimulated cattle peripheral blood mononuclear cells (PBMCs) were investigated. Enzyme-linked immunosorbent assay (ELISA) was used to analyze monoclonal antibodies against rCTLA-4 and rPD-L1. Antibodies generated from peripheral blood mononuclear cells of healthy and BLV-seropositive cows were employed to evaluate their blocking capabilities. The resulting recombinant proteins specifically reacted with commercial homogeneous monoclonal antibodies (mAbs) using ELISA and anti-His-tag mAbs using western blotting. Analysis of the proteins using LC-MS/MS revealed correspondence with the sequences of rCTLA-4 and rPD-L1 located in the Mascot database. rCTLA-4 and rPD-L1 proteins inhibited IFN-γ production in bovine PBMCs of activated SEB. When PBMCs from cows were cultured with activated SEB containing rCTLA-4 and rPD-L1, the mAbs increased IFN-γ production in PBMCs. The combined cultivation of mAbs and PBMCs from BLV+ cattle enhanced IFN-γ production in the cells. These findings suggest that the combined blockade of bovine CTLA-4 and PD-L1 receptors can be used as a therapy for bovine leukemia. However, it was shown that a single PBMC sample from a BLV-positive donor did not amplify the synergistic effect. Therefore, it is necessary to perform further studies on a larger population and assessing a wider range of cytokines.

Optimizing oral immune tolerance to Type II collagen in patients with rheumatoid arthritis: The importance of dose, interfering medication and genetics

ObjectivesOral immune tolerance (OT) is a complex process with unknown genetic regulation. Our aim is to explore possible genetic control of OT in patients with rheumatoid arthritis (RA). MethodsRA patients with increased interferon γ production invitro when their isolated peripheral blood mononuclear cells (PBMC) were cultured with type II bovine collagen α1 chain [α1 (II)] were enrolled in this study and were randomly assigned to the "Low dose" type II collagen (CII) group (30 µg/day for 10 weeks, followed by 50 µg/day for 10 weeks, followed by 70 µg/day for 10 weeks) or "High dose" CII group (90 µg/day for 10 weeks, followed by 110 µg/day for 10 weeks, followed by 130 µg/day for 10 weeks). Heparinized blood was obtained at baseline and after each of the 10 weeks treatment for analysis of the invitro production of IFNγ by their PBMC stimulated by α1(II) . Single nucleotide polymorphism (SNP) analysis of the responders and non-responders to oral CII was conducted using GeneChip Mapping 10 K 2.0 Array. ResultsThe SNP A-15,737 was found to associate with the ability of CII to suppress IFNγ production by α1(CII)-stimulated RA PBMC. The potential for SNP A-15,737 to associate with the OT response for patients with another autoimmune disease [OT induced by oral type I bovine collagen (CI) in patients with diffuse cutaneous systemic sclersodid (dsSSc)] was also explored. ConclusionsThe ROT1 region plays a role in the control of IFNγ production after oral dosing of auto-antigens, thereby determining if oral tolerance to that antigen will develop.

Mycobacterium tuberculosis produces d-serine under hypoxia to limit CD8+ T cell-dependent immunity in mice

Adaptation to hypoxia is a major challenge for the survival of Mycobacterium tuberculosis (Mtb) in vivo. Interferon (IFN)-γ-producing CD8+ T cells contribute to control of Mtb infection, in part by promoting antimicrobial activities of macrophages. Whether Mtb counters these responses, particularly during hypoxic conditions, remains unknown. Using metabolomic, proteomic and genetic approaches, here we show that Mtb induced Rv0884c (SerC), an Mtb phosphoserine aminotransferase, to produce d-serine. This activity increased Mtb pathogenesis in mice but did not directly affect intramacrophage Mtb survival. Instead, d-serine inhibited IFN-γ production by CD8+ T cells, which indirectly reduced the ability of macrophages to restrict Mtb upon co-culture. Mechanistically, d-serine interacted with WDR24 and inhibited mTORC1 activation in CD8+ T cells. This decreased T-bet expression and reduced IFN-γ production by CD8+ T cells. Our findings suggest an Mtb evasion mechanism where pathogen metabolic adaptation to hypoxia leads to amino acid-dependent suppression of adaptive anti-TB immunity.

Viperin inhibits interferon-γ production to promote Mycobacterium tuberculosis survival by disrupting TBK1-IKKε-IRF3-axis and JAK-STAT signaling

Objectives and designAs an interferon-inducible protein, Viperin has broad-spectrum antiviral effects and regulation of host immune responses. We aim to investigate how Viperin regulates interferon-γ (IFN-γ) production in macrophages to control Mycobacterium tuberculosis (Mtb) infection.MethodsWe use Viperin deficient bone-marrow-derived macrophage (BMDM) to investigate the effects and machines of Viperin on Mtb infection.ResultsViperin inhibited IFN-γ production in macrophages and in the lung of mice to promote Mtb survival. Further insight into the mechanisms of Viperin-mediated regulation of IFN-γ production revealed the role of TANK-binding kinase 1 (TBK1), the TAK1-dependent inhibition of NF-kappa B kinase-epsilon (IKKε), and interferon regulatory factor 3 (IRF3). Inhibition of the TBK1-IKKε-IRF3 axis restored IFN-γ production reduced by Viperin knockout in BMDM and suppressed intracellular Mtb survival. Moreover, Viperin deficiency activated the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathway, which promoted IFN-γ production and inhibited Mtb infection in BMDM. Additionally, a combination of the anti-TB drug INH treatment in the absence of Viperin resulted in further IFN-γ production and anti-TB effect.ConclusionsThis study highlights the involvement of TBK1-IKKε-IRF3 axis and JAK-STAT signaling pathways in Viperin-suppressed IFN-γ production in Mtb infected macrophages, and identifies a novel mechanism of Viperin on negatively regulating host immune response to Mtb infection.

Increased levels of villus-derived exosomal miR-29a-3p in normal pregnancy than uRPL patients suppresses decidual NK cell production of interferon-γ and exerts a therapeutic effect in abortion-prone mice

ObjectiveRecurrent pregnancy loss (RPL) patients have higher absolute numbers of decidual natural killer (dNK) cells with elevated intracellular IFN-γ levels leading to a pro-inflammatory cytokine milieu, which contributes to RPL pathogenesis. The main objective of this study was twofold: first to explore the regulatory effects and mechanisms of villus-derived exosomes (vEXOs) from induced abortion patients or RPL patients at the level of intracellular IFN-γ in dNK cells; second to determine the validity of application of vEXOs in the treatment of unexplained RPL (uRPL) through in vitro experiments and mouse models.MethodsExosomes were isolated from villus explants by ultracentrifugation, co-cultured with dNK cells, and purified by enzymatic digestion and magnetically activated cell sorting. Flow cytometry, enzyme-linked immunosorbent assays, and RT-qPCR were used to determine IFN-γ levels. Comparative miRNA analysis of vEXOs from induced abortion (IA) and uRPL patients was used to screen potential candidates involved in dNK regulation, which was further confirmed by luciferase reporter assays. IA-vEXOs were electroporated with therapeutic miRNAs and encapsulated in a China Food and Drug Administration (CFDA)-approved hyaluronate gel (HA-Gel), which has been used as a clinical biomaterial in cell therapy for > 30 years. In vivo tracking was performed using 1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyaine iodide (DiR) labelling. Tail-vein and uterine horn injections were used to evaluate therapeutic effects of the engineered exosomes in an abortion-prone mouse model (CBA/J × DBA/2 J). Placental growth was evaluated based on placental weight. IFN-γ mRNA levels in mouse placentas were measured by RT-qPCR.ResultsIFN-γ levels were significantly higher in dNK cells of uRPL patients than in IA patients. Both uRPL-vEXOs and IA-vEXOs could be efficiently internalized by dNK cells, whereas uRPL-vEXOs could not reduce the expression of IFN-γ by dNK cells as much as IA-vEXOs. Mechanistically, miR-29a-3p was delivered by vEXOs to inhibit IFN-γ production by binding to the 3′ UTR of IFN-γ mRNA in dNK cells. For in vivo treatment, application of the HA-Gel effectively prolonged the residence time of vEXOs in the uterine cavity via sustained release. Engineered vEXOs loaded with miR-29a-3p reduced the embryo resorption rate in RPL mice with no signs of systemic toxicity.ConclusionOur study provides the first evidence that villi can regulate dNK cell production of IFN-γ via exosome-mediated transfer of miR-29a-3p, which deepens our understanding of maternal–fetal immune tolerance for pregnancy maintenance. Based on this, we developed a new strategy to mix engineered vEXOs with HA-Gel, which exhibited good therapeutic effects in mice with uRPL and could be used for potential clinical applications in uRPL treatment.Graphical

Tumor-associated macrophages impair NK cell IFN-γ production and contribute to tumor progression in clear cell renal cell carcinoma.

Tumor-associated macrophages (TAM) are abundant in several tumor types and usually correlate with poor prognosis. Previously, we demonstrated that anti-inflammatory macrophages (M2) inhibit NK cell effector functions. Here, we explored the impact of TAM on NK cells in the context of clear-cell renal cell carcinoma (ccRCC). Bioinformatics analysis revealed that an exhausted NK cell signature strongly correlated with an M2 signature. Analysis of TAM from human ccRCC samples confirmed that they exhibited an M2-skewed phenotype and inhibited IFN-γ production by NK cells. Moreover, human M0 macrophages cultured with conditioned media from ccRCC cell lines generated macrophages with an M2-skewed phenotype (TAM-like), which alike TAM, displayed suppressive activity on NK cells. Moreover, TAM depletion in the mouse Renca ccRCC model resulted in delayed tumor growth and reduced volume, accompanied by an increased frequency of IFN-γ-producing tumor-infiltrating NK cells that displayed heightened expression of T-bet and NKG2D and reduced expression of the exhaustion-associated co-inhibitory molecules PD-1 and TIM-3. Therefore, in ccRCC, the tumor microenvironment polarizes TAM toward an immunosuppressive profile that promotes tumor-infiltrating NK cell dysfunction, contributing to tumor progression. In addition, immunotherapy strategies targeting TAM may result in NK cell reinvigoration, thereby counteracting tumor progression.

An orally available cancer drug AZD6738 prevents type 1 diabetes.

Type 1 diabetes (T1D) affects three million Americans, with 80 new people diagnosed each day. T1D is currently uncurable and there is an urgent need to develop additional drug candidates to achieve the prevention of T1D. We propose AZD6738 (ATRi), an orally available drug currently in phases I and II of clinical trials for various cancers, as a novel candidate to prevent T1D. Based on previously reported findings of ATRi inducing cell death in rapidly proliferating T cells, we hypothesized that this drug would specifically affect self-antigen activated diabetogenic T cells. These cells, if left unchecked, could otherwise lead to the destruction of pancreatic β cells, contributing to the development of T1D. This work demonstrates that increasing the duration of ATRi treatment provides extended protection against T1D onset. Remarkably, 5-week ATRi treatment prevented T1D in a robust adoptive transfer mouse model. Furthermore, the splenocytes of animals that received 5-week ATRi treatment did not transfer immune-mediated diabetes, while the splenocytes from control animal transferred the disease in 10 days. This work shows that ATRi prevents T1D by specifically inducing cell death in self-antigen activated, highly proliferative diabetogenic T cells through the induction of DNA damage, resulting in the inhibition of IFNγ production and proliferation. These findings support the consideration of repurposing ATRi for T1D prevention.

IFN-γ inhibitory molecules derived from Eimeria maxima inhibit IL-12 secretion by modulating MAPK pathways in chicken macrophages

IFN-γ plays a crucial role in resisting intracellular parasitic protozoa, such as Eimeria species. In our previous study, we identified 4 molecules derived from Eimeria maxima (E. maxima) that significantly inhibited IFN-γ production. However, the mechanism underlying this inhibitory effect remains unknown. In this study, we first investigated the effects of these 4 IFN-γ inhibitory molecules on the expression levels of chicken Toll-like receptors (chTLRs), IL-12, IL-10, TGF-β, and TNF-α in chicken macrophage HD11 and bone marrow-derived dendritic cells (BMDCs). The results demonstrated that these 4 inhibitory molecules significantly downregulated the mRNA levels of chTLR-2, chTLR-4, chTLR-21, and both mRNA and protein levels of IL-12. Subsequently, to clarify the effects of these 4 inhibitory molecules on the IL-12 secretion-related signaling pathways in chicken macrophages, qRT-PCR and Western blot were used to detect the changes of key molecules involved in the signaling pathways of IL-12 secretion (NF-κB, ERK1/2, p38, JNK, STAT3) following coincubation with these inhibitory molecules. Finally, RNAi was employed to verify the function of key molecules in the signaling pathway. The results revealed a significant upregulation in the expression of ERK1/2 phosphorylated protein induced by the 4 inhibitory molecules. Knockdown of the ERK1/2 gene significantly reduced the inhibitory effect of the 4 E. maxima inhibitory molecules on IL-12. These findings indicate that the 4 inhibitory molecules can inhibit the secretion of IL-12 by upregulating the expression of ERK1/2 phosphorylated protein, which is a key molecule in the ERK-MAPK pathway. Our study may contribute to elucidating the mechanisms underlying immune evasion during E. maxima infections, thereby providing new insights for the control of chicken coccidiosis.

Bacillus Calmette-Guérin-induced interleukin-10 inhibits S100A8/A9 production and hinders development of T helper type 1 memory in mice.

Tuberculosis caused by Mycobacterium tuberculosis (M.tb)is one of the main causes of human death in the world. Bacillus Calmette-Guérin (BCG) provides limited protection in adolescents and adults. To explore the factors reducing efficacy of BCG vaccine, we assess the impacts of interleukin (IL)-10 and alarmins S100A8/A9 on T-cell memory. We found that BCG-induced IL-10 inhibited production of S100A8/A9 in human peripheral blood mononuclear cells (PBMCs) and murine splenocytes. S100A9 deficiency inhibited IFN-γ production by CD4+ T cells in the early phase of BCG immunization and hindered the development of effector memory T helper type 1 (Th1) cells, while IL-10 deficiency promoted Th1 memory and blocking IL-10 signaling enhanced Th1 protective recall response against M.tb. IL-10 inhibited the binding of transcription factor CCAAT enhancer binding protein beta to S100a8/a9 promoter leading to S100A8/A9 reduction. S100A8/A9 heterodimer enhanced the IFN-γ production via receptor for advanced glycation end products signaling in CD4+ T cells. Our results demonstrate a hurdle to development of Th1 memory after BCG immunization and clarify the mechanism of the regulation of Th1 memory by IL-10 and S100A8/A9.

CD73 Inhibits cGAS-STING and Cooperates with CD39 to Promote Pancreatic Cancer.

The ectonucleotidases CD39 and CD73 catalyze extracellular ATP to immunosuppressive adenosine, and as such, represent potential cancer targets. We investigated biological impacts of CD39 and CD73 in pancreatic ductal adenocarcinoma (PDAC) by studying clinical samples and experimental mouse tumors. Stromal CD39 and tumoral CD73 expression significantly associated with worse survival in human PDAC samples and abolished the favorable prognostic impact associated with the presence of tumor-infiltrating CD8+ T cells. In mouse transplanted KPC tumors, both CD39 and CD73 on myeloid cells, as well as CD73 on tumor cells, promoted polarization of infiltrating myeloid cells towards an M2-like phenotype, which enhanced tumor growth. CD39 on tumor-specific CD8+ T cells and pancreatic stellate cells also suppressed IFNγ production by T cells. Although therapeutic inhibition of CD39 or CD73 alone significantly delayed tumor growth in vivo, targeting of both ectonucleotidases exhibited markedly superior antitumor activity. CD73 expression on human and mouse PDAC tumor cells also protected against DNA damage induced by gemcitabine and irradiation. Accordingly, large-scale pharmacogenomic analyses of human PDAC cell lines revealed significant associations between CD73 expression and gemcitabine chemoresistance. Strikingly, increased DNA damage in CD73-deficient tumor cells associated with activation of the cGAS-STING pathway. Moreover, cGAS expression in mouse KPC tumor cells was required for antitumor activity of the CD73 inhibitor AB680 in vivo. Our study, thus, illuminates molecular mechanisms whereby CD73 and CD39 seemingly cooperate to promote PDAC progression.

EXTH-54. CO-CULTURE OF PATIENT-DERIVED GLIOBLASTOMA CELL LINES WITH AUTOLOGOUS PBMCS FOR THE INVESTIGATION OF ONCOLYTIC VIRUS RESPONSE

Abstract BACKGROUND The dismal prognosis of glioblastoma (GBM) patients, with a median survival of less than 15 months despite maximal therapy urgently warrants new therapeutic approaches. Clinical trials employing oncolytic viruses (OVs) have shown encouraging results, however, in each OV clinical trial only a small subset of patients responded to treatment. As inter-tumoral heterogeneity has been the key challenge in treating GBM, we hypothesized that development of an in vitro co-culture model for assessment of viral replication and subsequent immune response might ultimately predict in vivo OV efficacy for individual GBM patients. METHODS 20 patient-derived GBM cell cultures were tested with dose-ranges of two clinically relevant OVs (DNX2401 and rQnestin34.5 V1) to determine the EC50 values (half-maximal effective concentration). To discriminate between responders and non-responders six of these cultures were infected using MOI 10 for DNX2401 and 0.25 for rQnestin34.5V1, and co-cultured with autologous PBMCs. OV-induced changes in gene and protein expression of immune associated genes were assessed using targeted gene expression (NanoString Technology) and ELISA. RESULTS DNX2401 EC50 values ranged from 0.35 to > 600 and from 0.04 to 1.77 for rQnestin34.5V1. Induction of pro-inflammatory cytokines and chemokines differed per virus and per patient. Enhanced OV infection or oncolysis efficiency did not lead to increased levels of IFNγ production. Importantly, longer exposure to dexamethasone prior to PBMC isolation correlated with suppressed IFNγ production. CONCLUSION We established an autologous GBM cells/PBMCs co-culture model which reflects inter-tumoral heterogeneity in terms of cytokine induction and virus-specific changes in gene and protein expression upon OV infection. Immune activation is not directly related to degree of infection or oncolysis and can be hampered by prolonged prior dexamethasone use. These first results support our hypothesis that improved prediction of response rates in oncolytic virotherapy for GBM may require a personalized approach with an in vitro test system.

Lead suppresses interferon γ to induce splenomegaly via modification on splenic endothelial cells and lymphoid tissue organizer cells in mice.

Splenomegaly is a symptom characterized by the presence of an enlarged spleen. The impact of environmental factors on splenomegaly is largely unknown. In this study, C57BL/6 mice were treated with 125ppm or 1250ppm lead (Pb) via drinking water for 8 wk, and the process of splenomegaly was evaluated. Treatment with 1250ppm Pb, but not 125ppm Pb, caused splenomegaly, which was associated with increased capacity for erythrocyte clearance. Intriguingly, Pb-caused splenomegaly was independent of lymphoid tissue inducer (LTi) cells, which produce lymphotoxins α and β (LTα/β) to activate endothelial cells and LT organizer (LTo) cells and drive the development of spleen physiologically. A direct action of Pb on endothelial cells and LTo cells did not impact their proliferation. On the other hand, during steady state, a tonic level of interferon (IFN)γ acted on endothelial cells and LTo cells to suppress splenomegaly, as IFNγ receptor (IFNγR)-deficient mice had enlarged spleens relative to wild-type mice; during Pb exposure, splenic IFNγ production was suppressed, thus leading to a loss of the inhibitory effect of IFNγ on splenomegaly. Mechanically, Pb acted on splenic CD4+ T cells to suppress IFNγ production, which impaired the Janus kinase (Jak)1/ signal transducer and activator of transcription (STAT)1 signaling in endothelial cells and LTo cells; the weakened Jak1/STAT1 signaling resulted in the enhanced nuclear factor-κB (NF-κB) signaling in endothelial cells and LTo cells, which drove their proliferation and caused splenomegaly. The present study reveals a previously unrecognized mechanism for the immunotoxicity of Pb, which may extend our current understanding for Pb toxicology.

NAMPT is a metabolic checkpoint of IFNγ-producing CD4+ T cells in lupus nephritis

Interferon γ (IFNγ) produced by Tcells represents the featured cytokine and is central to the pathogenesis of lupus nephritis (LN). Here, we identified nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme in the salvage NAD+ biosynthetic pathway, as playing a key role in controlling IFNγ production by CD4+ Tcells in LN. Our data revealed that CD4+ Tcells from LN showed an enhanced NAMPT-mediated NAD+ biosynthetic process, which was positively correlated with IFNγ production in CD4+ Tcells. NAMPT promoted aerobic glycolysis and mitochondrial respiration in CD4+ Tcells from patients with LN or MRL/lpr mice through the production of NAD+. By orchestrating metabolic fitness, NAMPT promoted translational efficiency of Ifng in CD4+ Tcells. Invivo, knockdown of NAMPT by small interfering RNA (siRNA) or pharmacological inhibition of NAMPT by FK866 suppressed IFNγ production in CD4+ Tcells, leading to reduced inflammatory infiltrates and ameliorated kidney damage in lupus mice. Taken together, this study uncovers a metabolic checkpoint of IFNγ-producing CD4+ Tcells in LN in which therapeutically targeting NAMPT has the potential to normalize metabolic competence and blunt pathogenicity of CD4+ Tcells in LN.

Immune State Conversion of the Mesenteric Lymph Node in a Mouse Breast Cancer Model.

Secondary lymphoid tissues, such as the spleen and lymph nodes (LNs), contribute to breast cancer development and metastasis in both anti- and pro-tumoral directions. Although secondary lymphoid tissues have been extensively studied, very little is known about the immune conversion in mesenteric LNs (mLNs) during breast cancer development. Here, we demonstrate inflammatory immune conversion of mLNs in a metastatic 4T1 breast cancer model. Splenic T cells were significantly decreased and continuously suppressed IFN-γ production during tumor development, while myeloid-derived suppressor cells (MDSCs) were dramatically enriched. However, T cell numbers in the mLN did not decrease, and the MDSCs only moderately increased. T cells in the mLN exhibited conversion from a pro-inflammatory state with high IFN-γ expression to an anti-inflammatory state with high expression of IL-4 and IL-10 in early- to late-stages of breast cancer development. Interestingly, increased migration of CD103+CD11b+ dendritic cells (DCs) into the mLN, along with increased (1→3)-β-D-glucan levels in serum, was observed even in late-stage breast cancer. This suggests that CD103+CD11b+ DCs could prime cancer-reactive T cells. Together, the data indicate that the mLN is an important lymphoid tissue contributing to breast cancer development.

Platelets correlate with false negative T-SPOT.TB results by inhibiting interferon-γ production in T cells via degranulation.

BackgroundT-SPOT.TB (T-SPOT) is widely used for the detection of Mycobacterium tuberculosis infection by detecting interferon-gamma (IFN-γ) release in T lymphocytes. This assay is performed on peripheral blood mononuclear cells (PBMCs) separated by Ficoll density gradient centrifugation, which often contain some residual platelets. Here, we investigated the impact of platelets on T-SPOT assay and related mechanisms.MethodsThe correlation between platelet count, platelet-to-lymphocyte ratio (PLR), and the IFN-γ secreting T cells (ISCs) in positive control wells of T-SPOT assay were retrospectively analyzed. T-SPOT assay was performed with un-treated PBMCs, platelets-removed PBMCs, and platelets-enriched PBMCs to confirm the impact of platelets on T-SPOT assay. The activation of platelets and their impact on IFN-γ production in T cells were detected by flow cytometry (FCM). Platelets and T cells were cultured in a mixed culture system and co-culture system respectively, followed by detection of the frequencies of IFN-γ-producing T cells and the levels of intracellular IFN-γ in T cells by FCM. Moreover, the effect of platelet releasate on the T-SPOT assay was evaluated.ResultsThe ISCs in positive control wells of the T-SPOT assay showed a significant decrease with the increase in platelet count. The PLR of the peripheral blood were negatively correlated with the ISCs in positive control wells of the T-SPOT assay. Removal or enrichment of platelets significantly increased or decreased the ISCs and the positive rate of T-SPOT. Inhibition of platelet activation significantly increased the ISCs of T-SPOT. The frequencies of IFN-γ-producing T cells in PBMCs and the levels of intracellular IFN-γ were significantly reduced by the addition of platelets, both in the mixed culture system and the co-culture system. Platelet releasate upon thrombin activation significantly decreased the ISCs of T-SPOT.ConclusionsPlatelets correlate with negative T-SPOT results by inhibiting IFN-γ production in T cells via degranulation.

Sulfate oligosaccharide of Gracilaria lemaneiformis modulates type 1 immunity by restraining T cell activation

Seaweeds are important “blue food” and some seaweeds have been demonstrated that have the immunoregulation activities and benefit for human health. However, which immune cell subsets are targeted and how immune processes are regulated by those seaweeds remain poorly understood. Here we identified sulfated oligosaccharide of Gracilaria lemaneiformis (GLSO) inhibits IFNγ production by T cells in ovalbumin (OVA) immunized mice and in vitro activation system of OVA-specific CD4+ T cells. Furthermore, GLSO predominantly targets T cells but not dendritic cells, and regulates the late stage of expression of T cell activation and differentiation markers. Mechanistically, results of transcriptomic and proteome analysis indicate that GLSO inhibits mTOR activity, glycolysis, cell cycle and DNA replication. Thus, GLSO has an immunomodulatory function in Th1 immune responses by restraining T cell activation. Our study unravels the anti-inflammatory mechanism of GLSO and provides a new insight for industrial development of seaweeds as health food.

Estradiol-induced immune suppression via prostaglandin E2 during parturition in bovine leukemia virus-infected cattle.

Immune suppression during pregnancy and parturition is considered a risk factor that is related to the progression of bovine chronic diseases, such as bovine leukosis, which is caused by bovine leukemia virus (BLV). Our previous studies have demonstrated that prostaglandin E2 (PGE2) suppresses BLV-specific Th1 responses and contributes to the disease progression during BLV infection. Although PGE2 reportedly plays important roles in the induction of parturition, PGE2 involvement in immune suppression during parturition is unknown. To investigate its involvement, we analyzed PGE2 kinetics and Th1 responses in BLV-infected pregnant cattle. PGE2 concentrations in sera were increased, whereas IFN-γ responses were decreased before delivery. PGE2 is known to suppress Th1 immune responses in cattle. Thus, these data suggest that PGE2 upregulation inhibits Th1 responses during parturition. We also found that estradiol was important for PGE2 induction in pregnant cattle. In vitro analyses indicated that estradiol suppressed IFN-γ production, at least in part, via PGE2/EP4 signaling. In vivo analyses showed that estradiol administration significantly influenced the induction of PGE2 production and impaired Th1 responses. Our data suggest that estradiol-induced PGE2 is involved in the suppression of Th1 responses during pregnancy and parturition in cattle, which could contribute to the progression of BLV infection.

Metformin ameliorates chronic colitis in a mouse model by regulating interferon-γ-producing lamina propria CD4+ T cells through AMPK activation.

Metformin, a commonly prescribed drug for type 2 diabetes mellitus, has been shown to activate AMP-activated protein kinase (AMPK). Notably, AMPK activation has recently been observed to be associated with anti-inflammatory responses. Metformin is also reported to elicit anti-inflammatory responses in CD4+ T cells, resulting in improvement in experimental chronic inflammatory diseases, such as systemic lupus erythematosus. To investigate the effect of metformin on inflammatory bowel disease (IBD), we developed a T cell-transfer model of chronic colitis in which SCID mice were injected with CD4+ CD45RBhigh T cells to induce colitis. We examined the effects of metformin via in vitro and in vivo experiments on lamina propria (LP) CD4+ T cells. We observed that metformin suppresses the frequency of interferon (IFN) -γ-producing LP CD4+ T cells in vitro, which were regulated by AMPK activation, a process possibly induced by the inhibition of oxidative phosphorylation. Furthermore, we examined the effects of metformin on an in vivo IBD model. Metformin-treated mice showed AMPK activation in LP CD4+ T cells and ameliorated colitis. Our study demonstrates that metformin-induced AMPK activation in mucosal CD4+ T cells contributes to the improvement of IBD by suppressing IFN-γ production. Moreover, our results indicate that AMPK may be a target molecule for the regulation of mucosal immunity and inflammation. Thus, AMPK-activating drugs such as metformin may be potential therapeutic agents for the treatment of IBD.