Th1 Polarization Research Articles

Antigen-presenting aged neutrophils induce CD4+ T cells to exacerbate inflammation in sepsis.

Extracellular cold-inducible RNA-binding protein (eCIRP) is a key mediator of severity and mortality in sepsis. We found that stimulation of mouse bone marrow-derived neutrophils (BMDNs) with eCIRP generated a distinct neutrophil subpopulation, characterized by cell surface markers of both antigen-presenting cells and aged neutrophils as well as expression of IL-12, which we named antigen-presenting aged neutrophils (APANs). The frequency of APANs was significantly increased in the blood, spleen, and lungs of WT mice subjected to cecal ligation and puncture-induced sepsis but not in CIRP-/- mice. Patients with sepsis had a significant increase in circulating APAN counts compared with healthy individuals. Compared with non-APAN-transfered mice, APAN-transferred septic mice had increased serum levels of injury and inflammatory markers, exacerbated acute lung injury (ALI), and worsened survival. APANs and CD4+ T cells colocalized in the spleen, suggesting an immune interaction between these cells. APANs cocultured with CD4+ T cells significantly induced the release of IFN-γ via IL-12. BMDNs stimulated with eCIRP and IFN-γ underwent hyper-NETosis. Stimulating human peripheral blood neutrophils with eCIRP also induced APANs, and stimulating human neutrophils with eCIRP and IFN-γ caused hyper-NETosis. Thus, eCIRP released during sepsis induced APANs to aggravate ALI and worsen the survival of septic animals via CD4+ T cell activation, Th1 polarization, and IFN-γ-mediated hyper-NETosis.

T Cell Activating Thermostable Self-Assembly Nanoscaffold Tailored for Cellular Immunity Antigen Delivery.

Antigen delivery based on non-virus-like particle self-associating protein nanoscffolds, such as Aquifex aeolicus lumazine synthase (AaLS), is limited due to the immunotoxicity and/or premature clearance of antigen-scaffold complex resulted from triggering unregulated innate immune responses. Here, using rational immunoinformatics prediction and computational modeling, wescreen the T epitope peptides from thermophilic nanoproteins with the same spatial structure as hyperthermophilic icosahedral AaLS, and reassemble them into a novel thermostable self-assembling nanoscaffold RPT that can specifically activate T cell-mediated immunity. Tumor model antigen ovalbumin T epitopes and the severe acute respiratory syndrome coronavirus 2 receptor-binding domain are loaded onto the scaffold surface through the SpyCather/SpyTag system to construct nanovaccines. Compared to AaLS, RPT -constructed nanovaccines elicit more potent cytotoxic T cell and CD4+ T helper 1 (Th1)-biased immune responses, and generate less anti-scaffold antibody. Moreover, RPT significantly upregulate the expression of transcription factors and cytokines related to the differentiation of type-1 conventional dendritic cells, promoting the cross-presentation of antigens to CD8+ T cells and Th1 polarization of CD4+ T cells. RPT confers antigens with increased stability against heating, freeze-thawing, and lyophilization with almost no antigenicity loss. This novel nanoscaffold offers a simple, safe, and robust strategy for boosting T-cell immunity-dependent vaccine development.

SIRT3 Activator Honokiol Inhibits Th17 Cell Differentiation and Alleviates Colitis.

Honokiol (HKL), a natural extract of the bark of the magnolia tree and an activator of the mitochondrial protein sirtuin-3 (SIRT3), has been proposed to possess anti-inflammatory effects. This study investigated the inhibitory effects of HKL on T helper (Th) 17 cell differentiation in colitis. Serum and biopsies from 20 participants with ulcerative colitis (UC) and 18 healthy volunteers were collected for the test of serum cytokines, flow cytometry analysis (FACS), and relative messenger RNA (mRNA) levels of T cell subsets, as well as the expression of SIRT3 and phosphorylated signal transducer and activator of transcription/retinoic acid-related orphan nuclear receptor γt (p-STAT3/RORγt) signal pathway in colon tissues. In vitro, naïve clusters of differentiation (CD) 4 + T cells isolated from the mouse spleen differentiated to subsets including Th1, Th2, Th17, and regulatory T (Treg) cells. Peripheral blood monocytes (PBMCs) from healthy volunteers were induced to the polarization of Th17 cells. After HKL treatment, changes in T cell subsets, related cytokines, and transcription factors were measured. The dextran sulfate sodium (DSS)-induced colitis and interleukin (IL)-10-deficient mice were intraperitoneally injected with HKL. These experiments were conducted to study the effect of HKL on the development, cytokines, and expression of signaling pathway proteins in colitis. Patients with UC had higher serum IL-17 and a higher proportion of Th17 differentiation in blood compared with healthy participants; while IL-10 level and the proportion of Treg cells were lower. Higher relative mRNA levels of RORγt and a lower SIRT3 expression in colon tissues were observed. In vitro, HKL had little effect on the differentiation of naïve CD4+ T cells to Th1, Th2, or Treg cells, but it downregulated IL-17 levels and the Th17 cell ratio in CD4+ T cells from the mouse spleen and human PBMCs under Th17 polarization. Even with a STAT3 activator, HKL still significantly inhibited IL-17 levels. In DSS-induced colitis mice and IL-10 deficient mice treated with HKL, the length of the colon, weight loss, disease activity index, and histopathological scores were improved, IL-17 and IL-21 levels, and the proportion of Th17 cells were decreased. Sirtuin-3 expression was increased, whereas STAT3 phosphorylation and RORγt expression were inhibited in the colon tissue of mice after HKL treatment. Our study demonstrated that HKL could partially protect against colitis by regulating Th17 differentiation through activating SIRT3, leading to inhibition of the STAT3/RORγt signaling pathway. These results provide new insights into the protective effects of HKL against colitis and may facilitate the research of new drugs for inflammatory bowel disease.

Eos Promotes TH2 Differentiation by Interacting with and Propagating the Activity of STAT5.

The Ikaros zinc-finger transcription factor Eos has largely been associated with sustaining the immunosuppressive functions of regulatory T cells. Paradoxically, Eos has more recently been implicated in promoting proinflammatory responses in the dysregulated setting of autoimmunity. However, the precise role of Eos in regulating the differentiation and function of effector CD4+ T cell subsets remains unclear. In this study, we find that Eos is a positive regulator of the differentiation of murine CD4+ TH2 cells, an effector population that has been implicated in both immunity against helminthic parasites and the induction of allergic asthma. Using murine invitro TH2 polarization and an invivo house dust mite asthma model, we find that EosKO T cells exhibit reduced expression of key TH2 transcription factors, effector cytokines, and cytokine receptors. Mechanistically, we find that the IL-2/STAT5 axis and its downstream TH2 gene targets are one of the most significantly downregulated pathways in Eos-deficient cells. Consistent with these observations, we find that Eos forms, to our knowledge, a novel complex with and supports the tyrosine phosphorylation of STAT5. Collectively, these data define a regulatory mechanism whereby Eos propagates STAT5 activity to facilitate TH2 cell differentiation.

Two Modes of Th1 Polarization Induced by Dendritic-Cell-Priming Adjuvant in Vaccination.

Viral infections are usually accompanied by systemic cytokinemia. Vaccines need not necessarily mimic infection by inducing cytokinemia, but must induce antiviral-acquired immunity. Virus-derived nucleic acids are potential immune-enhancers and particularly good candidates as adjuvants in vaccines in mouse models. The most important nucleic-acid-sensing process involves the dendritic cell (DC) Toll-like receptor (TLR), which participates in the pattern recognition of foreign DNA/RNA structures. Human CD141+ DCs preferentially express TLR3 in endosomes and recognize double-stranded RNA. Antigen cross-presentation occurs preferentially in this subset of DCs (cDCs) via the TLR3-TICAM-1-IRF3 axis. Another subset, plasmacytoid DCs (pDCs), specifically expresses TLR7/9 in endosomes. They then recruit the MyD88 adaptor, and potently induce type I interferon (IFN-I) and proinflammatory cytokines to eliminate the virus. Notably, this inflammation leads to the secondary activation of antigen-presenting cDCs. Hence, the activation of cDCs via nucleic acids involves two modes: (i) with bystander effect of inflammation and (ii) without inflammation. In either case, the acquired immune response finally occurs with Th1 polarity. The level of inflammation and adverse events depend on the TLR repertoire and the mode of response to their agonists in the relevant DC subsets, and could be predicted by assessing the levels of cytokines/chemokines and T cell proliferation in vaccinated subjects. The main differences in the mode of vaccine sought in infectious diseases and cancer are defined by whether it is prophylactic or therapeutic, whether it can deliver sufficient antigens to cDCs, and how it behaves in the microenvironment of the lesion. Adjuvant can be selected on a case-to-case basis.

Rubiginosin B selectively inhibits Treg cell differentiation and enhances anti-tumor immune responses by targeting calcineurin-NFAT signaling pathway

BackgroundThe accumulation of CD4+Foxp3+ regulatory T cells (Tregs) in the tumor microenvironment (TME) dampens anti-tumor immune responses and promotes tumor progression. Therefore, the elimination of Tregs has become a strategy to enhance the efficacy of tumor immunotherapy, although it is still a daunting challenge. Rhododendron brachypodum (R. brachypodum) is a perennial shrub mainly distributed in Southwestern China, whereas the chemical constituents in this plant remain elusive. PurposeTo identify small-molecule inhibitors of Tregs from R. brachypodum. MethodsMeroterpenoids in R. brachypodum were isolated by column chromatography under the guidance of LCMS analyses. The structures of isolates were identified by spectroscopic data and quantum calculations. The activities of compounds were first evaluated on CD4+ T cell differentiation by flow cytometry in Th1, Th2, Th17, and Treg polarizing conditions, and then on CT26 and MC38 murine colorectal carcinoma cells-allografted mice models. The mechanism of action was first investigated by determining Foxp3 degradation in Jurkat T cells transfected with pLVX-TetOne-Puro-Foxp3-tGFP, and then through analyses of Foxp3 expression on several pre-transcriptional signaling molecules. ResultsTwo new prenylated phenolic acids (1 and 2) and a chromane meroterpenoid, rubiginosin B (RGB, 3) were obtained from R. brachypodum. The structure of S-anthopogochromene C (1) was rectified according to the electronic circular dichroism (ECD) experiment, and rhodobrachypodic acid (2) was proposed as the precursor of RGB by photochemical transformation. In this investigation, we first found that RGB (3) selectively suppressed the de novo differentiation of TGFβ-induced CD4+Foxp3+ regulatory T cells (iTregs), overcome the immunosuppressive TME, and consequently inhibited the growth of tumor in mouse models. The mechanistic study revealed that RGB could target calcineurin, inhibited the nuclear factor of activated T cells (NFAT) dephosphorylation, and down-regulated Foxp3 expression. The hypothetical binding modes of RGB with calcineurin were predicted by molecular docking, and the interactions were mainly hydrophobic effects and hydrogen bonds. ConclusionThese results suggest that RGB enhances anti-tumor immune responses by inhibiting Treg cell differentiation through calcineurin-NFAT signaling pathway, and therefore RGB or its analogs may be used as adjuvant agents meriting further investigation.

Regulating the immune response to carbon tetrachloride-induced liver fibrosis in mice by blocking inducible co-stimulatory molecules and interleukin-33

Objective: To investigate the effects of combined blockade of interleukin-33 (IL-33) and inducible co-stimulatory molecule (ICOS) on carbon tetrachloride-induced chronic liver fibrosis and imbalance of T helper lymphocyte subsets in mice. Methods: There were 40 BALB/c mice in each model and control group. Flow cytometry was used to determine the proportion of Th1/Th2/Th17 cells in the splenic lymphocyte suspension of mice, the expression levels of interferon γ, IL-4, and IL-17 in the splenic lymphocyte suspension of liver fibrosis mice after combined blockade of IL-33 and ICOS, and the pathological changes of liver histopathology in mice with liver fibrosis. Two independent sample t-test was used to compare data between groups. Results: Compared with the non-blocking group, the proportion of Th2 and Th17 cells in the IL-33/ICOS blocking group was significantly down-regulated (Th2: 65.96% ± 6.04% vs. 49.09% ± 7.03%; Th17: 19.17% ± 4.03% vs. 9.56% ± 2.03%), while the proportion of Th1 cells and Th1/Th2 ratio were up-regulated (Th1: 17.14% ± 3.02% vs. 31.93% ± 5.02%; Th1/Th2: 0.28 ± 0.06 vs. 0.62 ± 0.23), and the difference was statistically significant (t = 5.15, 6.03, 7.14, 4.28, respectively, with P < 0.05). After entering the chronic inflammation stage of liver fibrosis in mice (10 weeks), compared with the non-blocking group, the expression levels of IL-4 and IL-17 in the blockade group were significantly down-regulated [IL-4: (84.75 ± 14.35) pg/ ml vs. (77.88 ± 19.61) pg/ml; IL-17: (72.38 ± 15.13) pg/ml vs. (36.38 ± 8.65) pg/ml], while the expression of interferon γ was up-regulated [(37.25 ± 11.51) pg/ml vs. (77.88 ± 19.61) pg/ml], and the difference was statistically significant (t: IL-4: 4.71; IL-17: 5.84; interferon γ: 5.05, respectively, with P < 0.05). Liver histopathological results showed that hepatic necrosis, hepatic lobular structural disorder, and fibrous tissue hyperplasia were significantly lower in the blockade group than those in the non-blocking group at 13 weeks of liver fibrosis. Conclusion: Combined blockade of the ICOS signaling pathway and IL-33 can regulate Th2 and Th17 polarization, down-regulate the inflammatory response, and inhibit or prevent the occurrence and progression of fibrosis.

Acetate regulates GAPDH acetylation and T helper 1 cell differentiation.

The short-chain fatty acid metabolite acetyl-coenzyme A (acetyl-CoA) has emerged as a major signal transducer that can broadly affect cell fate and function, at least partly by influencing acetylation of key proteins. The mechanism by which acetyl-CoA regulates CD4+ T-cell fate determination remains poorly understood. Herein, we report that acetate modulates glyceraldehyde-3-phosphate dehydrogenase (GAPDH) acetylation and CD4+ T helper 1 (Th1) cell differentiation by altering acetyl-CoA levels. Our transcriptome profiling shows that acetate is a robust positive regulator of CD4+ T-cell gene expression typical of glycolysis. We further show that acetate potentiates GAPDH activity, aerobic glycolysis, and Th1 polarization through regulation of GAPDH acetylation levels. This acetate-dependent GAPDH acetylation occurs in a dose- and time-dependent manner, while decreasing acetyl-CoA levels by fatty acid oxidation inhibition results in a decline in acetyl-GAPDH levels. Thus, acetate functions as a potent metabolic regulator in CD4+ T-cells by promoting GAPDH acetylation and Th1 cell fate decision.

Ineffective polarization characterizes CD4 T cell responses to persistent Borrelia burgdorferiinfection

Abstract Borrelia burgdorferi (Bb), the spirochetal agent of Lyme disease, evades immune clearance in infected mice and humans, suggesting ongoing immune suppression. Here we explored the functionality of Bb-induced CD4 T cell responses in infected mice, which are considered Th1 polarized. Surprisingly, in vitro restimulation of CD4 T cells from mice infected for 12 days failed to induce secretion of the hallmark Th1 cytokine IFNg. Consistent with that data, flow cytometry and RNAseq of CD4 T cells from lymph nodes (LNs) of Bb-infected mice at 6, 10, 14, and 21 days post infection (dpi) showed a transient Th1 and Th17 polarization that peaked at 10 dpi before declining, confirmed also by RT-PCR. While Th1 and Th17 gene expression profiles returned to baseline by 14 dpi, increased frequencies of CXCR4+ CXCR5+ PD-1 hiICOS+ BCL6+ T follicular helper (Tfh) cells emerged at that time, concomitant with germinal center induction. The lack of CD4 T cell effector polarization was noted also in the skin, an effector site after Bb infection, as well as in antigen-specific T cells, which were identified using a new MHCII tetramer to the Bb surface antigen arthritis related protein (Arp). Together, our results indicate a failure to sustain effector CD4 T cell polarization after Bb infection, identifying CD4 T cells as a potential target of Bb-mediated immune suppression. This work was supported by grants from the Global Lyme Alliance, the Stephen &amp; Alexander Cohen Foundation, NIH R01AI157007 (NB) and T32 AI060555 (EMH). This work was supported by grants from the Global Lyme Alliance, the Stephen &amp; Alexander Cohen Foundation, NIH R01AI157007 (NB) and T32 AI060555 (EMH).

D-2-hydroxyglutarate decreases allergic sensitization in asthma

Abstract Allergic asthma is a chronic inflammatory disease affecting the lungs which is mediated by allergen-specific IgE and type 2 cytokines. IgE and type 2 cytokine production require Tfh13 cell and Th2 cell polarization, respectively, which must first be primed by dendritic cells (DC). Recent studies demonstrate that cellular metabolic perturbations critically regulate DC activation and subsequent T cell priming. To characterize DC metabolic mechanisms which may regulate allergic sensitization, we analyzed GWAS data to identify metabolism-related genes that are associated with asthma risk. We identified 384 single nucleotide polymorphisms (SNPs) in the D2HGDHlocus that are significantly associated with childhood-onset asthma. Further, expression quantitative trait loci analysis of the 10 most significant SNPs revealed that these SNPs promote reduced expression of D2HGDHmRNA. D2HGDH is an enzyme which catalyzes the conversion of D-2-hydroxyglutarate (D-2HG) to α-ketoglutarate (aKG). D-2HG is a potent inhibitor of aKG-dependent epigenetic enzymes. Bone marrow-derived dendritic cells (BMDCs) stimulated with the fungal allergen Alternariaexhibited a significant increase in the ratio of aKG/D-2HG compared to mock or LPS treated BMDCs. Further, in vivostudies revealed that intranasal administration of cell-permeable D-2HG prior to intranasal exposure to Alternariasignificantly reduced Th2 and Tfh13 polarization, impaired IgE+ germinal center B cell differentiation, and induced T follicular regulatory cell polarization in mice. Our results suggest a mechanism whereby D-2HG suppresses epigenetic modifications in DCs, which are necessary for allergic sensitization and polarization of Th2 and Tfh13 cells. VCU CTSA UL1TR002649 as well as funding from NIAID R56AI139658

BLOC1S1: An Unexpected Regulator of Th2 Cell-driven Inflammatory Responses

Abstract BLOC1S1 is an adaptor protein that modulates endosome-lysosome function as a component of numerous multiprotein complexes. We postulated that its modulation in CD4 +T cells may help us uncover the role of endosome-lysosome biology in adaptive immunity. In primary CD4 +T cells BLOC1S1 cre-recombinase knockout resulted in the preferential induction of Th2 compared to Th1 and Th17 cytokine production following T cell receptor activation. As atopic dermatitis is an allergic inflammatory skin disease characterized by the production of the type 2 cytokines in the skin we evaluated the effect of CD4 +T cell BLOC1S1 KO vs controls in calcipotriol-induced atopic dermatitis in mice. The absence of BLOC1S1 exhibited exacerbated atopic dermatitis accompanied with significantly elevated plasma IgE, skin eosinophilia, elevated type 2 responses, and inflammatory pathology relative to wild-type mice. The transcription factor Gata-3 is expressed in Th2 but not Th1 cells and plays a critical role in Th2 differentiation and atopic dermatitis. BLOC1S1 deficient CD4 +T cells showed enhanced nuclear factor kB (NF-kB), Gata3 and LC3 positive autophagosomes. Inhibition of NF-kB activity prevented Gata-3 expression, LC3 positive autophagosomes and Th2 cytokine production in BLOC1S1 −/− CD4 +T cells. This mouse model will now give us a platform to explore the role of endo-lysosomal biology in Th2 polarization and activation. NHLBI Division of Intramural Research (MNS-ZIA-HL005102)

UCP2 Deficiency Renders Th1/2 Pathogenic Phenotype to CD4+ T cells

Abstract Uncoupling protein 2 (UCP2) is an anion transporter in the mitochondrial matrix that controls ROS production, calcium influx, and C4 metabolites. It is regarded as a metabolic regulator. A lack of UCP2 has led to an extreme clinical score with higher oxidative stress and inflammation in autoimmune illness, even though elevated UCP2 has been found in many tumors and is known to be a potential target for tumor therapy. Uncertainty still exists regarding UCP2’s function in T cells. A significant rise in the Th2/Th1 ratio was seen in this work using CD4 cells from UCP2−/− mice. These cells exhibited an improved Th2 phenotype with decreased calcium influx, elevated iNOS expression, and elevated urea metabolism. CD4 cells were treated with NOC-18, a source of nitric oxide, or Genipin to demonstrate nitric oxide-mediated Th2 polarization (inhibitor for UCP2). There were more cytotoxic markers and Th2/Th1 double positive cells. The B16/F10 tumor cells were controlled in vitro in a tumor killing assay utilizing genipin-treated CD4 cells, according to the findings. However, in UCP2−/− mice, the severity of EAE worsened, and heterogenic Th2 cells were infiltrated into central nerves system. Our findings imply that the loss of UCP2 in CD4 increases Th2 polarization with a cytotoxic phenotype and may be relevant to various illnesses. R01 CA250458, R01 CA236379

PI3Kδ shapes Th2 lineage restriction through coordination of IL-2 signaling, Foxo1 inactivation and epigenetic remodeling

Abstract Activated PI3K-delta syndrome (APDS) is a primary immunodeficiency caused by heterozygous activating mutations in PI3Kδ, resulting in recurrent infections as well as allergic diseases. Given that APDS patients show an inability to clear respiratory pathogens (Th1) and development of allergic diseases (Th2), we hypothesized that hyperactivated PI3Kδ (Pik3cd E1020K) may alter CD4 T cell differentiation. Using in vitro polarization of murine naïve CD4 T cells, we observed increased production of IFNγ from Pik3cd E1020Kmice under Th1 inducing conditions and marked increases in IL-4 and IL-13 production under Th2 conditions. However, Pik3cd E1020KTh2 cells also expressed high levels of Tbet and aberrantly produced IFNγ. Strikingly, this dysregulation was also observed in vivo; Pik3cd E1020KCD4 cells show pronounced alterations following house dust mite induced airway inflammation, with impaired Th2 and inappropriate polarization to Th1 responses as visualized by scRNAseq. We linked this unstable Th1 and Th2 differentiation in Pik3cd E1020KCD4 T cells in vitro to hyper-responsiveness to IL-2, associated with increased phosphorylation and inactivation of transcription factor Foxo1. CRISPR-mediated targeting of Foxo1 in naïve WT CD4 cells recapitulated the Pik3cd E1020Kphenotype. Transcriptomic analysis of Pik3cd E1020KCD4 T cells revealed differential expression of genes involved in histone methylation. Accordingly, Pik3cd E1020KCD4 exhibit altered chromatin modifications, including H3K27 and H3K4 trimethylation. Together these data suggest that balanced regulation of PI3Kδ plays a critical role in enforcing Th1 and Th2 lineage identity. This research was supported by the Intramural Research Program of NIAID, NIH

Mitochondrial translation inhibition in CD4+T cells selectively sensitizes the Th2 subset to increased cell death

Abstract Upon stimulation with antigen, resting T cells undergo extensive proliferation followed by differentiation into effector cells and long-lived memory cells. Upregulation of mitochondrial oxidative phosphorylation (OXPHOS) is essential for the activation and proliferation of resting T cells. Mitochondrial DNA encodes 13 proteins, which are integral parts of the complexes that form the mitochondrial respiratory chain. Since mitochondrial ribosomes are evolutionarily similar to bacterial ribosomes, antibiotics targeting bacterial ribosomes inhibit mitochondrial protein synthesis as well. But how these antibiotics affect T cell proliferation and differentiation is not well understood. To address this, we used chloramphenicol to inhibit mitochondrial translation during the activation of naive murine CD4+T cells in Th1 or Th2 polarizing conditions. Cell proliferation and effector functions were reduced in both Th1 and Th2 cells when activated in presence of chloramphenicol. Moreover, chloramphenicol significantly altered metabolic reprogramming in Th1 and Th2 cells indicated by a lower rate of OXPHOS and upregulation of glycolysis to maximum levels. Interestingly, inhibition of mitochondrial translation resulted in increased apoptosis following activation specifically in the Th2 effector subset. Th2 cells displayed a significant increase in caspase 3/7 activity upon mitochondrial translation inhibition. RNA sequencing analysis identified the upregulation of Bim and Puma in Th2 cells, two pro-apoptotic proteins that are known to be upregulated in response to metabolic stress. These results show that Th2 cells specifically undergo apoptosis in response to antibiotics that target mitochondrial translation. Support from ICMR, NII-DBT

Airway goblet cells resulting from conditional YAP/TAZ deletion promote distinct pulmonary inflammation

Abstract The aberrant presence of goblet cells, which are epithelial cells of the conducting airways that have specialized roles in secreting mucus, is frequently associated with distinct innate and adaptive immune changes that together are hallmarks of various pulmonary diseases. The transcriptional regulators YAP and TAZ, key effectors of Hippo pathway signaling, play a central role in suppressing the differentiation of airway goblet cells. Here we investigated the consequences of goblet cell production, resulting from the YAP/TAZ conditional depletion in Scgb1a1+ secretory cells, on lung immunity. We observed that loss of YAP/TAZ resulted in the production of goblet cells promoting local CD45+ immune cell expansion. To gain insight into immune changes associated with the production of YAP/TAZ-deleted goblet cells, we performed a single-cell RNA sequencing experiment on CD45+ cells isolated from control and Yap/Taz-cNull mouse lungs. Data analyses, along with follow-up validation experiments, demonstrated significant immune changes in Yap/Taz-cNull mice including an expansion of type 2 innate lymphoid cells (ILC2s), CD4+ T cells Th2 polarization, and alternative activation of alveolar macrophages, accompanied with elevated type 2 cytokine production. Gene expression analysis of YAP/TAZ-deleted airway cells revealed altered expression of notable immune-modulating factors, many of which are implicated in lung diseases. Collectively our study demonstrates that key immune-modulating signals arise from the secretory lung epithelium through reduced YAP/TAZ activity, raising interesting questions about the functions of YAP/TAZ in lung homeostasis and about the contributions of goblet cells to shaping lung immune responses.

Proliferation, Plasticity, and Migration: Exploring the synergistic relationship between eosinophils and TH2 cells in development of HES-like syndrome

Abstract Aberrancies in eosinophil proliferation, activation and chemotaxis can lead to acute eosinophilic leukemia, paraneoplastic eosinophilia associated with T cell lymphoma and carcinomas, and Hypereosinophilic Syndrome (HES), respectively. HES is an idiopathic disease affecting humans and veterinary patients characterized by persistent eosinophilia (&amp;gt;1,500 cells/uL) and eosinophilic infiltration of solid organs leading to increased morbidity and mortality. Previous studies have demonstrated the role of NF-κB inducing kinase, NIK, an upstream regulator of the noncanonical NF-κB signaling pathway, in development of a HES-like syndrome due to aberrant TH2 polarization in the Nik−/−murine model. However, the intricacies of eosinophilic granulopoiesis, eosinophil/neutrophil plasticity, and chemotactic ability has not been assessed during development of HES-like syndrome in Nik−/−mice. Here we show that loss of NIK potentially enhances eosinophilic chemotaxis to CCL11, enhances eosinophilic/neutrophilic plasticity, and affects granulopoiesis in the bone marrow and spleen beginning at the level of eosinophilic metamyelocytes, despite potentially decreasing the proliferative potential of these cells. Taken together, these results suggest that NIK and the noncanonical NF-κB signaling pathway plays a role in dictating the hematopoietic and chemotactic potential of eosinophils and highlights a synergistic relationship with TH2 cells and their respective cytokines during development of HES-like syndrome in Nik−/−mice. Overall, these findings warrant further study to better characterize the synergistic relationship described above to better understand development of HES and HES-like diseases. Virginia-Maryland College of Veterinary Medicine and the Institute for Critical Technology and Applied Science

A Human STAT3 Gain of Function Variant Drives Th17 Expansion and IL-22-dependent Skin Inflammation in a Model of Psoriasiform Dermatitis

Patients with germline gain-of-function (GOF) variants in signal transducer and activator of transcription 3 (STAT3) present with early-onset polyautoimmunity, including psoriasis. STAT3 is a pleiotropic transcription factor that plays a role in the proliferation, survival, and function of many different cell types. In T cells, STAT3 is required for the polarization and function of Th17 cells and can inhibit development of peripheral Tregs. We hypothesized that STAT3 GOF variants enhance Th17 responses following an inflammatory stimulus, leading to autoimmune disease. To examine this, we generated a mouse model of STAT3 GOF using an amino acid substitution identified in patients (p.G421R). Aged STAT3 GOF mice develop spontaneous skin inflammation of the ears associated with increased neutrophil and T cell infiltration into the skin. The frequency of Th17 in the aged skin was also increased compared to age-matched WT littermates. In adult STAT3 GOF mice, Th17 polarization of naïve T cells was enhanced in vitro, indicating a potential for CD4 skewing toward Th17. To test if this would drive disease susceptibility in vivo, WT and STAT3 GOF mice were treated with topical imiquimod (IMQ). Following treatment, STAT3 GOF mice demonstrated increased ear swelling and an increased Th17 response in the skin and periphery. Adaptive lymphocytes mediated this response; however, CD8T cells and γδ T cells are not required. Analysis of T cell clonality by scRNA-seq revealed an increased frequency of expanded clones in untreated and IMQ-treated CD4 and CD8T cells of effector and exhausted subsets. Among the expanded clones, Il22 transcript was upregulated in STAT3 GOF IMQ-treated CD4s. IL-22 was then found to partially mediate the response to IMQ in STAT3 GOF. Using bone marrow chimeras, we identified a role for both radiosensitive and resistant cells in this inflammatory response. We also observed a competitive advantage for STAT3 GOF Th17 cells in the skin. Collectively, these data demonstrate that STAT3 GOF results in a cell-intrinsic skewing of T cells with a Th17 phenotype, suggesting a potential mechanism for the development of autoimmunity and a target for therapeutics in patients with STAT3 GOF syndrome.

Prohibitin is Upregulated on Donor T cells in Murine Acute Graft-versus-Host Disease and Promotes Th17 Response

Abstract Introduction: Acute graft-versus-host disease (GVHD) is a T cell-mediated disorder and the main cause of non-relapse mortality in allogeneic hematopoietic cell transplantation recipients. Here, we investigate PHB in Th17-mediated inflammation and as a therapeutic target for acute GVHD. Methods: Irradiated mice received T cell depleted bone marrow cells and allogeneic or syngeneic splenocytes. At day 25 post-transplant, blood, spleen, liver, and colon were harvested and analyzed for surface PHB, IFNγ, and IL-17 on donor T cells by flow cytometry. Splenocytes were cultured in the presence of PHB pharmacological inhibitor rocaglamide (RocA) and analyzed for PHB and IL-17 expression in donor T cells. Naïve murine CD4 T cells were cultured in Th17 polarizing conditions with RocA. CRISPR/Cas9-mediated knockout of PHB was performed followed by evaluation of Il17a, Il17f, and Il22 gene expression by quantitative PCR. Results: Surface expression of PHB is increased in murine allogeneic donor T cells in liver, spleen, colon, and peripheral blood in acute GVHD. PHB-expressing splenic T cells secrete IL-17, which is reduced with treatment with a PHB inhibitor in ex vivo experiments. PHB inhibition of murine CD4 T cells in vitro impairs differentiation into the Th17 subtype resulting in reduced IL-17 secretion and downregulation of Il17a, Il17f, and Il22 genes. Knockout of PHB reduces transcription of Il17 and Il22 genes. Conclusions: These findings show relevancy of PHB in Th17-mediated inflammation and suggest a potential role for PHB in acute GVHD. To our knowledge, this study is the first to investigate PHB in acute GVHD, and our findings will offer greater support for clinical use of PHB inhibition to treat this fatal disease. Supported by grants from AAI (KS, PR), ACS (PR; RSG-22-053-01-IBCD), and NIH NCI (PR; R01 CA252469).

P130 Transcriptomic analysis of synovitis identifies inhibition of CXCL1 as a mechanism contributing to resolution of inflammatory arthritis under IL-27 control

Abstract Background/Aims Interleukin-27 (IL-27) regulates adaptive immune responses and is critical for the timely resolution of inflammation to restore tissue homeostasis. Studies have highlighted roles for IL-27 in limiting immune cell effector function, stromal cell responses and erosive joint pathology in clinical rheumatoid arthritis and experimental models of the disease. In the murine antigen-induced arthritis (AIA) model, IL-27 receptor-deficient (Il27ra-/-) mice develop severe synovitis associated with increased infiltration of synovial CD4+ T cells, development of synovial ectopic lymphoid-like structures and exacerbated cartilage and bone erosion. Similarly, mice with collagen-induced arthritis (CIA) administered IL-27 show improved joint pathology and reduced serum IFN-γ and IL-17 levels. Identifying mechanisms by which IL-27 regulates arthritis progression is key to understanding its therapeutic potential. Using RNA-sequencing of synovial tissue and joint-infiltrating CD4+ T cells we reveal that IL-27 regulates the magnitude of synovitis and genes in CD4+ T cells central to neutrophil recruitment. Methods Antigen-induced arthritis (AIA) was established in Il27ra-/- and wild-type control mice. RNA-sequencing was performed on whole synovial tissue and joint-infiltrating CD4+ T cells during the peak of joint inflammation and during the resolution of synovitis. Differentially expressed genes were interrogated by molecular pathway analysis and gene set enrichment analysis. CD4+ T cell culture assays, qPCR and ELISA were used to test and validate genes under IL-27 regulation. Results RNA-sequencing of whole synovial tissue revealed that pathways relating to CD4+ T cell and Th17 biology were significantly overrepresented in Il27ra-/- mice with AIA, consistent with a pathogenic role for these cells in inflammatory arthritis. Genes associated with neutrophil effector function (e.g. Elane, Padi4, Prtn3) and recruitment (e.g. Cxcl1, Cxcr2) were also highly expressed in Il27ra-/- synovium and was reflected in the increased number of Ly6G+CD11b+ neutrophils recovered from the joints of Il27ra-/- mice. In contrast to the transcriptomic analysis of inflamed synovial tissue, surprisingly RNA-sequencing of joint-infiltrating CD4+ T cells revealed that the expression of signature Th17 genes (e.g. Il17a, Il17f, Rorc) was comparable between WT and Il27ra-/- T cells. This implies that IL-27 predominantly regulates the magnitude of the joint CD4+ T cell infiltrate more than the effector characteristics of the infiltrating T cells. Differential gene expression analysis revealed heightened Cxcl1 expression in both whole synovial tissue and joint-infiltrating CD4+ T cells recovered from Il27ra-/- mice with AIA. CD4+ T cell differentiation cultures confirmed upregulation of Cxcl1 following T cell receptor activation and under Th1 polarizing conditions. Here, IL-27 suppressed the expression of CXCL1 at the mRNA and protein level. Conclusion Together, our data reveals a role for IL-27 in limiting CXCL1 expression in activated and joint-infiltrating CD4+ T cells, highlighting a novel mechanism by which IL-27 may integrate innate and adaptive arms of the immune response to regulate arthritis progression. Disclosure I. Burridge: None. S. Eastham: None. D.G. Hill: None. R. Andrews: None. B. Szomolay: None. N. Williams: None. S.A. Jones: None. G.W. Jones: None.

Natural Microbial Exposure from the Earliest Natural Time Point Enhances Immune Development by Expanding Immune Cell Progenitors and Mature Immune Cells.

Microbial experience fundamentally shapes immunity, particularly during the perinatal period when the immune system is underdeveloped, and novel microbial encounters are common. Most animal models are raised in specific pathogen-free (SPF) conditions with relatively uniform microbial communities. How SPF housing conditions alter early-life immune development relative to natural microbial exposure (NME) has not been thoroughly investigated. In this article, we compare immune development in SPF-raised mice with mice born from immunologically experienced mothers in microbially diverse environments. NME induced broad immune cell expansion, including naive cells, suggesting mechanisms besides activation-induced proliferation contribute to the increase in immune cell numbers. We found NME conditions also expanded immune cell progenitor cell populations in the bone marrow, suggesting microbial experience enhances immune development at the earliest stages of immune cell differentiation. Multiple immune functions characteristically impaired in infants were also enhanced by NME, including T cell memory and Th1 polarization, B cell class switching and Ab production, proinflammatory cytokine expression, and bacterial clearance after Listeria monocytogenes challenge. Collectively, our studies reveal numerous impairments in immune development in SPF conditions relative to natural immune development.