STING trafficking activates MAPK-CREB signaling to trigger regulatory T cell differentiation.

The Type-I interferon (IFN-I) response is the major outcome of stimulator of interferon genes (STING) activation in innate cells. STING is more abundantly expressed in adaptive T cells; nevertheless, its intrinsic function in T cells remains unclear. Intriguingly, we previously demonstrated that STING activation in T cells activates widespread IFN-independent activities, which stands in contrast to the well-known STING-mediated IFN response. Here, we have identified that STING activation induces regulatory T cells (Tregs) differentiation independently of IRF3 and IFN. Specifically, the translocation of STING from the endoplasmic reticulum to the Golgi activates mitogen-activated protein kinase (MAPK) activity, which subsequently triggers transcription factor cAMP response element-binding protein (CREB) activation. The activation of the STING-MAPK-CREB signaling pathway induces the expression of many cytokine genes, including interleukin-2 (IL-2) and transforming growth factor-beta 2 (TGF-ß2), to promote the Treg differentiation. Genetic knockdown of MAPK p38 or pharmacological inhibition of MAPK p38 or CREB markedly inhibits STING-mediated Treg differentiation. Administration of the STING agonist also promotes Treg differentiation in mice. In the Trex1-/- autoimmune disease mouse model, we demonstrate that intrinsic STING activation in CD4+ T cells can drive Treg differentiation, potentially counterbalancing the autoimmunity associated with Trex1 deficiency. Thus, STING-MAPK-CREB represents an IFN-independent signaling axis of STING that may have profound effects on T cell effector function and adaptive immunity.

The effectiveness of ruxolitinib and cyclophosphamide combination on T helper 17 and regulatory T cells in rat experimental membranous glomerulonephritis.

The progression and pathogenesis of membranous glomerulonephritis (MGN) are inextricably linked to chronic inflammation. Despite improving clinical remission rates due to the application of cyclophosphamide (CYC), treatment of MGN still requires further exploration. Ruxolitinib (Ruxo) negatively affects the signaling pathways participating in the production of pro-inflammatory cytokines. Hence, we investigated whether the combination of CYC and Ruxo can modulate inflammation through influencing T helper 17 (Th17) lineages and regulatory T cells (Tregs). Passive Heymann nephritis (PHN), an experimental model of MGN, was induced in a population of rats. Then, the animals were divided into five groups: PHN, CYC-receiving, Ruxo-receiving, CYC-Ruxo-receiving PHN rats, and healthy controls. After 28 days of treatment, biochemistry analysis was performed and splenocytes were isolated for flowcytometry investigation of Th17 cells and Tregs. The correlative transcription factors of the cells, alongside their downstream cytokine gene expressions, were also assessed using real-time PCR. Furthermore, serum cytokine signatures for the lymphocytes were determined through ELISA. The combination of CYC and Ruxo significantly reduced the serum values of urea in rats versus the PHN group (24.62 ± 7.970 vs. 40.60 ± 10.81 mg/dL). In contrast to Treg's activities, the functionality of Th17 cells noticeably increased not only in PHN rats but also in CYC or Ruxo-receiving PHN animals when compared with the control (10.60 ± 2.236, 8.800 ± 1.465, 8.680 ± 1.314 vs. 4.420 ± 1.551 %). However, in comparison to the PHN group, the incidence of Th17 cells notably fell in rats receiving CYC and Ruxo (10.60 ± 2.236 vs. 6.000 ± 1.373 %) in favor of the Treg's percentage (5.020 ± 1.761 vs. 8.980 ± 1.178 %), which was verified by the gene expressions and cytokine productions correlative to these lymphocytes. The combination of CYC and Ruxo was able to decline Th17 cells in favor of Tregs improvement in PHN rats, suggesting an innovative combination therapy in MGN treatment approaches.

Rejection resistant CD30.CAR-modified Epstein-Barr virus-specific T cells as an off-the-shelf platform for CD30+ lymphoma.

Off-the-shelf (OTS) adoptive T cell therapies have many benefits such as immediate availability, improved access and reduced cost, but face the major challenges of graft-vs-host disease (GVHD) and graft rejection, mediated by alloreactive T cells present in the graft and host, respectively. We have developed a platform for OTS T cell therapies by using Epstein-Bar virus (EBV)-specific T cells (EBVSTs) expressing a chimeric antigen receptor (CAR) targeting CD30. Allogeneic EBVSTs have not caused GVHD in several clinical trials, while the CD30.CAR, that is effective for the treatment of lymphoma, can also target alloreactive T cells that upregulate CD30 on activation. Although EBVSTs express high levels of CD30, they were protected from fratricide in cis, by the CD30.CAR. Hence, they could proliferate extensively and maintained function both through their native EBV-specific T cell receptor and the CD30.CAR. The CD30.CAR enabled EBVSTs to persist in co-cultures with naive and primed alloreactive T cells and eliminate activated natural killer cells that can also be alloreactive. In conclusion, we show that CD30.CAR EBVSTs have the potential to be an effective OTS therapy against CD30+ tumors and, if successful, could then be used as a platform to target other tumor antigens.

IL-27 expression regulation and its effects on adaptive immunity against viruses.

IL-27, a member of the IL-6/IL-12 cytokine superfamily, is primarily secreted by antigen presenting cells, specifically by dendric cells, macrophages and B cells. IL-27 has antiviral activities and modulates both innate and adaptive immune responses against viruses. The role of IL-27 in the setting of viral infections is not well defined and both pro-inflammatory and anti-inflammatory functions have been described. Here, we discuss the latest advancements in the role of IL-27 in several viral infection models of human disease. We highlight important aspects of IL-27 expression regulation, the critical cell sources at different stages of the infection and their impact in cell mediated immunity. Lastly, we discuss the need to better define the antiviral and modulatory (pro-inflammatory vs anti-inflammatory) properties of IL-27 in the context of human chronic viral infections.

Immune phenotype-genotype associations in primary clear cell renal cell carcinoma and matched metastatic tissue.

Adjuvant immunotherapy has been recently recommended for patients with metastatic ccRCC, but there are no tissue biomarkers to predict treatment response in ccRCC. Potential predictive biomarkers are mainly assessed in primary tumor tissue, whereas metastases remain understudied. To explore potential differences between genomic alterations and immune phenotypes in primary tumors and their matched metastases, we analyzed primary tumors (PTs) of 47 ccRCC patients and their matched distant metastases (METs) by comprehensive targeted parallel sequencing, whole-genome copy number variation (CNV) analysis, determination of microsatellite instability (MSI) and tumor mutational burden (TMB). We quantified the spatial distribution of tumor-infiltrating CD8+ T cells, and co-expression of the T-cell-exhaustion marker TOX by digital immunoprofiling and quantified tertiary lymphoid structures (TLS). Most METs were pathologically "cold". Inflamed, pathologically "hot" PTs were associated with a decreased disease-free survival (DFS), worst for patients with high levels of CD8+TOX+ T cells. Interestingly, inflamed METs showed a relative increase of exhausted CD8+TOX+ T cells and increased accumulative size of TLS compared to PTs. Integrative analysis of molecular and immune phenotypes revealed BAP1 and CDKN2A/B deficiency to be associated with an inflamed immune phenotype. Our results highlight the distinct spatial distribution and differentiation of CD8+ T cells at metastatic sites, and the association of an inflamed microenvironment with specific genomic alterations.

Engineering strategies to safely drive CAR T-cells into the future.

Chimeric antigen receptor (CAR) T-cell therapy has proven a breakthrough in cancer treatment in the last decade, giving unprecedented results against hematological malignancies. All approved CAR T-cell products, as well as many being assessed in clinical trials, are generated using viral vectors to deploy the exogenous genetic material into T-cells. Viral vectors have a long-standing clinical history in gene delivery, and thus underwent iterations of optimization to improve their efficiency and safety. Nonetheless, their capacity to integrate semi-randomly into the host genome makes them potentially oncogenic via insertional mutagenesis and dysregulation of key cellular genes. Secondary cancers following CAR T-cell administration appear to be a rare adverse event. However several cases documented in the last few years put the spotlight on this issue, which might have been underestimated so far, given the relatively recent deployment of CAR T-cell therapies. Furthermore, the initial successes obtained in hematological malignancies have not yet been replicated in solid tumors. It is now clear that further enhancements are needed to allow CAR T-cells to increase long-term persistence, overcome exhaustion and cope with the immunosuppressive tumor microenvironment. To this aim, a variety of genomic engineering strategies are under evaluation, most relying on CRISPR/Cas9 or other gene editing technologies. These approaches are liable to introduce unintended, irreversible genomic alterations in the product cells. In the first part of this review, we will discuss the viral and non-viral approaches used for the generation of CAR T-cells, whereas in the second part we will focus on gene editing and non-gene editing T-cell engineering, with particular regard to advantages, limitations, and safety. Finally, we will critically analyze the different gene deployment and genomic engineering combinations, delineating strategies with a superior safety profile for the production of next-generation CAR T-cell.

Integrated analysis of single-cell RNA-seq, bulk RNA-seq, Mendelian randomization, and eQTL reveals T cell-related nomogram model and subtype classification in rheumatoid arthritis.

Objective: Rheumatoid arthritis (RA) is a systemic disease that attacks the joints and causes a heavy economic burden on humans worldwide. T cells regulate RA progression and are considered crucial targets for therapy. Therefore, we aimed to integrate multiple datasets to explore the mechanisms of RA. Moreover, we established a T cell-related diagnostic model to provide a new method for RA immunotherapy. Methods: scRNA-seq and bulk-seq datasets for RA were obtained from the Gene Expression Omnibus (GEO) database. Various methods were used to analyze and characterize the T cell heterogeneity of RA. Using Mendelian randomization (MR) and expression quantitative trait loci (eQTL), we screened for potential pathogenic T cell marker genes in RA. Subsequently, we selected an optimal machine learning approach by comparing the nine types of machine learning in predicting RA to identify T cell-related diagnostic features to construct a nomogram model. Patients with RA were divided into different T cell-related clusters using the consensus clustering method. Finally, we performed immune cell infiltration and clinical correlation analyses of T cell-related diagnostic features. Results: By analyzing the scRNA-seq dataset, we obtained 10,211 cells that were annotated into 7 different subtypes based on specific marker genes. By integrating the eQTL from blood and RA GWAS, combined with XGB machine learning, we identified a total of 8 T cell-related diagnostic features (MIER1, PPP1CB, ICOS, GADD45A, CD3D, SLFN5, PIP4K2A, and IL6ST). Consensus clustering analysis showed that RA could be classified into two different T-cell patterns (Cluster 1 and Cluster 2), with Cluster 2 having a higher T-cell score than Cluster 1. The two clusters involved different pathways and had different immune cell infiltration states. There was no difference in age or sex between the two different T cell patterns. In addition, ICOS and IL6ST were negatively correlated with age in RA patients. Conclusion: Our findings elucidate the heterogeneity of T cells in RA and the communication role of these cells in an RA immune microenvironment. The construction of T cell-related diagnostic models provides a resource for guiding RA immunotherapeutic strategies.

Relations of optimism and purpose in life to immune markers in aging.

OBJECTIVE: Optimism and purpose in life are associated with improved health outcomes. More information is needed on biological mechanisms, including immunosenescence. We investigated if psychological well-being is associated with healthier immunosenescence-related measures including naïve and terminally differentiated CD4+ and CD8+ T cell percentages, CD4+:CD8+, and cytomegalovirus (CMV) IgG response. METHODS: Participants were adults over age 50 from the Health and Retirement Study. Optimism was measured using the Life Orientation Test Revised. Purpose in life was assessed using the subscale from the Ryff psychological well-being measure. We examined the cross-sectional associations of optimism and purpose in life with measures of T cell subsets using linear regression and with CMV IgG using ordered logit regression, controlling for potential confounding factors. RESULTS: The final analytic sample ranged from 7250 to 7870. After adjusting for sociodemographic factors, a 1-SD increment in optimism was associated with the percentage of naïve CD4+ T cells increasing by 0.6 (95%CI 0.2%, 1.0%). A 1-SD increment in purpose in life was associated with the percentage of naïve CD4+ T cells increasing by 0.9 (95%CI 0.5%, 1.3%) after adjusting for sociodemographic factors and the association was maintained after further adjustments for health conditions, depression, and health behaviors. For naïve CD8+ T cell percentages, CD4:CD8 ratios, and CMV IgG antibodies, associations were seen only in models that adjusted for age. No significant associations were seen in any models for the terminally differentiated CD4+ and CD8+ T cells. CONCLUSIONS: We found associations of optimism and purpose in life with naïve CD4+ T cell percentages.

Peripheral Lymphocyte Changes Associate With the Progression of Necrotizing Enterocolitis in Infants.

INTRODUCTION: Immune factors are important antecedents in the pathophysiology of necrotizing enterocolitis (NEC). However, studies on the peripheral blood lymphocyte subsets changes in NEC patients among different Bell stages and in patients requiring surgery are scarce. METHODS: 34 infants with NEC and 33 age-matched controls were included. Peripheral blood was collected within 48 h after NEC diagnosis. Peripheral blood B and T lymphocytes subsets were detected by 12-color flow cytometry. Cell ratios were calculated, and their relationship to disease severity and their roles as indicators for surgery were assessed. RESULTS: NEC patients showed elevated percentages of unSwB cells (CD27+IgD+ unswitched memory/activated B cells)/B cells, SwB cells (CD27+IgD-switched memory B cells)/B cells, CD8+ T (CD3+CD8+ T cells)/T cells, Tem (CD45RA-CCR7-effector memory T cells)/CD4+ T cells, Tem/CD8+ T cells and decreased Bn (CD27-IgD+ naïve B cells)/B cells, CD4+T (CD3+CD4+ T cells)/T cells, CD45RA+ CCR7+ naïve T cells (CD45RA+CCR7+ naïve T cells)/CD8+T cells. Compared to NEC patients at BELL stage I + II, patients at BELL stage III showed increased percentages of SwB cells/B cells, antibody secreting cell (ASC, CD3-CD20-CD27high CD38high ASCs)/B cells and Tem/CD4+ T cells, and decreased percentages of CD45RA+CCR7+ naïve T cells/CD4+ T cells. The Receiver Operating Characteristic Curve analysis showed that the sensitivity of ASC/B cells ratio (0.52%) is 86.67% and the specificity of Tem/CD4+T ratio (5.22%) is 100%, indicating that NEC patients required surgery. CONCLUSIONS: The severity of NEC exhibits codirectional changes with the maturation of B and T lymphocytes, especially CD4+ T cells. The increased ASC/B and Tem/CD4+ T cells could serve as potential indicators for NEC patients requiring surgery.

CD38 and extracellular NAD+ regulate the development and maintenance of Hp vaccine-induced CD4+ TRM in the gastric epithelium.

Tissue-resident memory T cells (TRM) can be induced by infection and vaccination, and play a key role in maintaining long-term protective immunity against mucosal pathogens. Our studies explored the key factors and mechanisms affecting the differentiation, maturation, and stable residence of gastric epithelial CD4+ TRM induced by Helicobacter pylori (Hp) vaccine and optimized Hp vaccination to promote the generation and residence of TRM.CD38 regulated mitochondrial activity and enhanced TGF-ß signal transduction to promote the differentiation and residence of gastric epithelial CD4+ TRM by mediating the expression of CD105. Extracellular nucleotides influenced the long-term maintenance of TRM in gastric epithelium by P2RX7. Vitamin D3 and Gram-positive enhancer matrix particles (GEMs)as immune adjuvants combined with Hp vaccination promoted the production of CD69+CD103+CD4+ TRM.

Corrigendum: Patients with juvenile idiopathic arthritis have decreased clonal diversity in the CD8+ T cell repertoire response to influenza vaccination.

[This corrects the article DOI: 10.3389/fimmu.2024.1306490.].

CD161+CD127+CD8+ T cell subsets can predict the efficacy of anti-PD-1 immunotherapy in non-small cell lung cancer with diabetes mellitus.

The role of CD161+CD127+CD8+ T cells in non-small cell lung cancer (NSCLC) patients with diabetes remains unexplored. This study determined the prevalence, phenotype, and function of CD8+ T cell subsets in NSCLC with diabetes. We recruited NSCLC patients (n = 436) treated with anti-PD-1 immunotherapy as first-line treatment. The progression-free survival (PFS), overall survival (OS), T cells infiltration, and peripheral blood immunological characteristics were analyzed in NSCLC patients with or without diabetes. NSCLC patients with diabetes exhibited shorter PFS and OS (p = 0.0069 and p = 0.012, respectively) and significantly lower CD8+ T cells infiltration. Mass cytometry by time-of-flight (CyTOF) showed a higher percentage of CD161+CD127+CD8+ T cells among CD8+T cells in NSCLC with diabetes before anti-PD-1 treatment (p = 0.0071) than that in NSCLC without diabetes and this trend continued after anti-PD-1 treatment (p = 0.0393). Flow cytometry and multiple-immunofluorescence confirmed that NSCLC with diabetes had significantly higher CD161+CD127+CD8+ T cells to CD8+T cells ratios than NSCLC patients without diabetes. The RNA-sequencing analysis revealed immune-cytotoxic genes were reduced in the CD161+CD127+CD8+ T cell subset compared to CD161+CD127-CD8+ T cells in NSCLC with diabetes. CD161+CD127+CD8+ T cells exhibited more T cell-exhausted phenotypes in NSCLC with diabetes. NSCLC patients with diabetes with ≥ 6.3% CD161+CD127+CD8+ T cells to CD8+T cells ratios showed worse PFS. These findings indicate that diabetes is a risk factor for NSCLC patients who undergo anti-PD-1 immunotherapy.CD161+CD127+CD8+ T cells could be a key indicator of a poor prognosis in NSCLC with diabetes. Our findings would help in advancing anti-PD-1 therapy in NSCLC patients with diabetes.

Candidate tumor-specific CD8+ T cell subsets identified in the malignant pleural effusion of advanced lung cancer patients by single-cell analysis.

Isolation of tumor-specific T cells and their antigen receptors (TCRs) from malignant pleural effusions (MPE) may facilitate the development of TCR-transduced adoptive cellular immunotherapy products for advanced lung cancer patients. However, the characteristics and markers of tumor-specific T-cells in MPE are largely undefined. To this end, to establish the phenotypes and antigen specificities of CD8+ T cells, we performed single-cell RNA and TCR sequencing of samples from three advanced lung cancer patients. Dimensionality reduction on a total of 4,983 CD8+ T cells revealed 10 clusters including naïve, memory, and exhausted phenotypes. We focused particularly on exhausted T cell clusters and tested their TCR reactivity against neoantigens predicted from autologous cancer cell lines. Four different TCRs specific for the same neoantigen and one orphan TCR specific for the autologous cell line were identified from one of the patients. Differential gene expression analysis in tumor-specific T cells relative to the other T cells identified CXCL13, as a candidate gene expressed by tumor-specific T cells. In addition to expressing CXCL13, tumor-specific T cells were present in a higher proportion of T cells co-expressing PDCD1(PD-1)/TNFRSF9(4-1BB). Furthermore, flow cytometric analyses in advanced lung cancer patients with MPE documented that those with high PD-1/4-1BB expression have a better prognosis in the subset of 57 adenocarcinoma patients (p = .039). These data suggest that PD-1/4-1BB co-expression might identify tumor-specific CD8+ T cells in MPE, which are associated with patients' prognosis. (233 words).

An in vitro model system for testing chemical effects on microbiome-immune interactions - examples with BPX and PFAS mixtures.

Introduction: More than 350,000 chemicals make up the chemical universe that surrounds us every day. The impact of this vast array of compounds on our health is still poorly understood. Manufacturers are required to carry out toxicological studies, for example on the reproductive or nervous systems, before putting a new substance on the market. However, toxicological safety does not exclude effects resulting from chronic exposure to low doses or effects on other potentially affected organ systems. This is the case for the microbiome-immune interaction, which is not yet included in any safety studies. Methods: A high-throughput in vitro model was used to elucidate the potential effects of environmental chemicals and chemical mixtures on microbiome-immune interactions. Therefore, a simplified human intestinal microbiota (SIHUMIx) consisting of eight bacterial species was cultured in vitro in a bioreactor that partially mimics intestinal conditions. The bacteria were continuously exposed to mixtures of representative and widely distributed environmental chemicals, i.e. bisphenols (BPX) and/or per- and polyfluoroalkyl substances (PFAS) at concentrations of 22 µM and 4 µM, respectively. Furthermore, changes in the immunostimulatory potential of exposed microbes were investigated using a co-culture system with human peripheral blood mononuclear cells (PBMCs). Results: The exposure to BPX, PFAS or their mixture did not influence the community structure and the riboflavin production of SIHUMIx in vitro. However, it altered the potential of the consortium to stimulate human immune cells: in particular, activation of CD8+ MAIT cells was affected by the exposure to BPX- and PFAS mixtures-treated bacteria. Discussion: The present study provides a model to investigate how environmental chemicals can indirectly affect immune cells via exposed microbes. It contributes to the much-needed knowledge on the effects of EDCs on an organ system that has been little explored in this context, especially from the perspective of cumulative exposure.

Unraveling the role of γδ T cells in the pathogenesis of an oncogenic avian herpesvirus.

Marek's disease virus (MDV) is an oncogenic alphaherpesvirus that causes deadly lymphomas in chickens. In chickens, up to 50% of all peripheral T cells are gamma delta (γδ) T cells. Until now, their role in MDV pathogenesis and tumor formation remains poorly understood. To investigate the role of γδ T cells in MDV pathogenesis, we infected recently generated γδ T cell knockout chickens with very virulent MDV. Strikingly, disease and tumor incidence were highly increased in the absence of γδ T cells, indicating that γδ T cells play an important role in the immune response against MDV. In the absence of γδ T cells, virus replication was drastically increased in the thymus and spleen, which are potential sites of T cell transformation. Taken together, our data provide the first evidence that γδ T cells play an important role in the pathogenesis and tumor formation of this highly oncogenic herpesvirus.IMPORTANCEGamma delta (γδ) T cells are the most abundant T cells in chickens, but their role in fighting pathogens remains poorly understood. Marek's disease virus (MDV) is an important veterinary pathogen, that causes one of the most frequent cancers in animals and is used as a model for virus-induced tumor formation. Our study revealed that γδ T cells play a crucial role in combating MDV, as disease and tumor incidence drastically increased in the absence of these cells. γδ T cells restricted virus replication in the key lymphoid organs, thereby decreasing the likelihood of causing tumors and disease. This study provides novel insights into the role of γδ T cells in the pathogenesis of this highly oncogenic virus.

Lymphotoxin ß receptor and tertiary lymphoid organs shape acute and chronic allograft rejection.

Solid organ transplantation remains the life-saving treatment for end-stage organ failure, but chronic rejection remains a major obstacle to long-term allograft outcomes and has not improved substantially. Tertiary lymphoid organs (TLO) are ectopic lymphoid structures that form under conditions of chronic inflammation, and evidence from human transplantation suggests that TLO regularly form in allografts undergoing chronic rejection. In this study, we utilized a mouse renal transplantation model and manipulation of the lymphotoxin alpha (LTα) - lymphotoxin beta receptor (LTßR) pathway, which is essential for TLO formation, to define the role of TLO in transplantation. We showed that intragraft TLO are sufficient to activate the alloimmune response and mediate graft rejection in a model where the only lymphoid organs are TLO in the allograft. When transplanted to recipients with a normal set of secondary lymphoid organs, the presence of graft TLO or LTα overexpression accelerated rejection. If the LTßR pathway was disrupted in the donor graft, TLO formation was abrogated, and graft survival prolonged. Intravital microscopy of renal TLO demonstrated that local T and B cell activation in TLOs is similar to that observed in secondary lymphoid organs. In summary, we demonstrated that immune activation in TLO contributes to local immune responses, leading to earlier allograft failure. TLO and the LTαß-LTßR pathway are therefore prime targets to limit local immune responses and prevent allograft rejection. These findings are applicable to other diseases such as autoimmunity or tumors, where either limiting or boosting local immune responses is beneficial and improves disease outcomes.

Iron capture through CD71 drives perinatal and tumor-associated Treg expansion.

Beside suppressing immune responses, regulatory T cells (Tregs) maintain tissue homeostasis and control systemic metabolism. Whether iron is involved in Treg-mediated tolerance is completely unknown. Here, we showed that the transferrin receptor CD71 was upregulated on activated Tregs infiltrating human liver cancer. Mice with a Treg-restricted CD71 deficiency spontaneously developed a scurfy-like disease, caused by impaired perinatal Treg expansion. CD71-null Tregs displayed decreased proliferation and tissue-Treg signature loss. In perinatal life, CD71 deficiency in Tregs triggered hepatic iron overload response, characterized by increased hepcidin transcription and iron accumulation in macrophages. Lower bacterial diversity, and reduction of beneficial species, were detected in the fecal microbiota of CD71 conditional knock-out neonates. Our findings indicate that CD71-mediated iron absorption is required for Treg perinatal expansion and related to systemic iron homeostasis and bacterial gut colonization. Therefore, we hypothesize that Tregs establish nutritional tolerance through competition for iron during bacterial colonization after birth.

Inhibiting the NADase CD38 improves cytomegalovirus-specific CD8+ T cell functionality and metabolism.

Cytomegalovirus (CMV) is one of the most common and relevant opportunistic pathogens in immunocompromised individuals such as kidney transplant recipients (KTRs). The exact mechanisms underlying the disability of cytotoxic T cells to provide sufficient protection against CMV in immunosuppressed individuals have not been identified yet. Here, we performed in-depth metabolic profiling of CMV-specific CD8+ T cells in immunocompromised patients and show the development of metabolic dysregulation at the transcriptional, protein, and functional level of CMV-specific CD8+ T cells in KTRs with non-controlled CMV infection. These dysregulations comprise impaired glycolysis and increased mitochondrial stress, which is associated with an intensified expression of the nicotinamide adenine dinucleotide nucleotidase (NADase) CD38. Inhibiting NADase activity of CD38 reinvigorated the metabolism and improved cytokine production of CMV-specific CD8+ T cells. These findings were corroborated in a mouse model of CMV infection under conditions of immunosuppression. Thus, dysregulated metabolic states of CD8+ T cells could be targeted by inhibiting CD38 to reverse hypo-responsiveness in individuals who fail to control chronic viral infection.

The canonical Hippo pathway components modulate the differentiation of lamina propria regulatory T cells and T helper 17-like regulatory T cells in mouse colitis.

Regulatory T cells (Tregs) ameliorate inflammatory bowel diseases. However, their plasticity is not completely understood. In this study using a mouse colitis model, Tregs and T helper 17 (Th17)-like Tregs were detected and sorted using flow cytometry, followed by transcriptome sequencing, real-time RT-PCR, and flow cytometry to analyze the mRNA profiles of these cells. Treg plasticity was evaluated by in vitro differentiation assays. The immunosuppressive activities of Tregs and Th17-like Tregs were assessed in an adoptive transfer assay. We found Tregs-derived Th17-like Tregs in inflamed colonic lamina propria (LP). LP Th17-like Tregs expressed higher Th17-related cytokines and lower immunosuppressive cytokines compared with LP Tregs. Notably, Tregs expressed higher Yes-associated protein 1 (YAP1) but lower transcriptional coactivator with PDZ­binding motif (TAZ) than Th17-like Tregs. Verteporfin-mediated inhibition of YAP1 activity enhanced Th17-like Treg generation, whereas IBS008739-induced TAZ activation did not affect Th17-like Treg generation. Besides, verteporfin enhanced while IBS008739 suppressed the differentiation of Th17-like Tregs into Th17 cells. Furthermore, YAP1 activated STAT5 signaling in Tregs, whereas YAP1 and TAZ activated STAT3 and STAT5 signaling in Th17-like Tregs. Compared with Tregs, Th17-like Tregs were less efficacious in ameliorating colitis. Therefore, YAP1 suppressed Treg differentiation into Th17-like Tregs. Both YAP1 and TAZ inhibited the differentiation of Th17-like Tregs into Th17 cells. Therefore, YAP1 and TAZ probably maintain the immunosuppressive activities of Tregs and Th17-like Tregs in colitis.

Serotonergic input from the dorsal raphe nucleus shapes learning-associated odor responses in the olfactory bulb.

AIM: Neural activity in the olfactory bulb (OB) can represent odor information during different brain and behavioral states. For example, the odor responses of mitral/tufted (M/T) cells in the OB change during learning of odor-discrimination tasks and, at the network level, beta power increases and the high gamma (HG) power decreases during odor presentation in such tasks. However, the neural mechanisms underlying these observations remain poorly understood. Here, we investigate whether serotonergic modulation from the dorsal raphe nucleus (DRN) to the OB is involved in shaping activity during the learning process in a go/no-go task in mice. METHODS: Fiber photometry was used to record the population activity of DRN serotonergic neurons during a go/no-go task. In vivo electrophysiology was used to record neural activity (single units and local field potentials) in the OB during the go/no-go task. Real-time place preference (RTPP) and intracranial light administration in a specific subarea (iClass) tests were used to assess the ability of mice to encoding reward information. RESULTS: Odor-evoked population activity in serotonergic neurons in the DRN was shaped during the learning process in a go/no-go task. In the OB, neural activity from oscillations to single cells showed complex, learning-associated changes and ability to encode information during an odor discrimination task. However, these properties were not observed after ablation of DRN serotonergic neurons. CONCLUSION: The activity of neural networks and single cells in the OB, and their ability to encode information about odor value, are shaped by serotonergic projections from the DRN.