Th1 Development Research Articles

Epicutaneous vaccination with protease inhibitor-treated papain prevents papain-induced Th2-mediated airway inflammation without inducing Th17 in mice

Environmental allergen sources such as house dust mites contain proteases, which are frequently allergens themselves. Inhalation with the exogenous proteases, such as a model of protease allergen, papain, to airways evokes release and activation of IL-33, which promotes innate and adaptive allergic airway inflammation and Th2 sensitization in mice. Here, we examine whether epicutaneous (e.c.) vaccination with antigens with and without protease activity shows prophylactic effect on the Th airway sensitization and Th2-medated airway inflammation, which are driven by exogenous or endogenous IL-33. E.c. vaccination with ovalbumin restrained ovalbumin-specific Th2 airway sensitization and/or airway inflammation on subsequent inhalation with ovalbumin plus papain or ovalbumin plus recombinant IL-33. E.c. vaccination with papain or protease inhibitor-treated papain restrained papain-specific Th2 and Th9 airway sensitization, eosinophilia, and infiltration of IL-33-responsive Th2 and group 2 innate lymphoid cells on subsequent inhalation with papain. However, e.c. vaccination with papain but not protease inhibitor-treated papain induced Th17 response in bronchial draining lymph node cells. In conclusions, we demonstrated that e.c. allergen vaccination via intact skin in mice restrained even protease allergen-activated IL-33-driven airway Th2 sensitization to attenuate allergic airway inflammation and that e.c. vaccination with protease allergen attenuated the airway inflammation similar to its derivative lacking the protease activity, although the former but not the latter promoted Th17 development. In addition, the present study suggests that modified allergens, of which Th17-inducing e.c. adjuvant activity such as the protease activity was eliminated, might be preferable for safer clinical applications of the e.c. allergen administration.

Suppression of Experimental Autoimmune Encephalomyelitis by ILT3.Fc.

Multiple sclerosis (MS) is a chronic autoimmune disease of the CNS that is characterized by demyelination, axonal loss, gliosis, and inflammation. The murine model of MS is the experimental autoimmune encephalopathy (EAE) induced by immunization of mice with myelin oligodendrocyte glycoprotein (MOG)35-55 Ig-like transcript 3 (ILT3) is an inhibitory cell surface receptor expressed by tolerogenic human dendritic cells. In this study, we show that the recombinant human ILT3.Fc protein binds to murine immune cells and inhibits the release of proinflammatory cytokines that cause the neuroinflammatory process that result in paralysis. Administration of ILT3.Fc prevents the rapid evolution of the disease in C57BL/6 mice and is associated with a profound reduction of proliferation of MOG35-55-specific Th1 and Th17 cells. Inhibition of IFN-γ and IL-17A in mice treated with ILT3.Fc is associated with delayed time of onset of the disease and its evolution to a peak clinical score. Neuropathological analysis shows a reduction in inflammatory infiltrates and demyelinated areas in the brains and spinal cords of treated mice. These results indicate that inhibition of Th1 and Th17 development provides effective suppression of EAE and suggests the feasibility of a clinical approach based on the use of ILT3.Fc for treatment of MS. Furthermore, our results open the way to further studies on the effect of the human ILT3.Fc protein in murine experimental models of autoimmunity and cancer.

IL-6 Is Not Absolutely Essential for the Development of a TH17 Immune Response after an Aerosol Infection with Mycobacterium tuberculosis H37rv

Anti-inflammatory treatment of chronic inflammatory diseases often increases susceptibility to infectious diseases such as tuberculosis (TB). Since numerous chronic inflammatory and autoimmune diseases are mediated by interleukin (IL)-6-induced T helper (TH) 17 cells, a TH17-directed anti-inflammatory therapy may be preferable to an IL-12-dependent TH1 inhibition in order to avoid reactivation of latent infections. To assess, however, the risk of inhibition of IL-6-dependent TH17-mediated inflammation, we examined the TH17 immune response and the course of experimental TB in IL-6- and T-cell-specific gp130-deficient mice. Our study revealed that the absence of IL-6 or gp130 on T cells has only a minor effect on the development of antigen-specific TH1 and TH17 cells. Importantly, these gene-deficient mice were as capable as wild type mice to control mycobacterial infection. Together, in contrast to its key function for TH17 development in other inflammatory diseases, IL-6 plays an inferior role for the generation of TH17 immune responses during experimental TB.

GAS6 signaling tempers Th17 development in patients with multiple sclerosis and helminth infection.

Multiple sclerosis (MS) is a highly disabling neurodegenerative autoimmune condition in which an unbalanced immune response plays a critical role. Although the mechanisms remain poorly defined, helminth infections are known to modulate the severity and progression of chronic inflammatory diseases. The tyrosine kinase receptors TYRO3, AXL, and MERTK (TAM) have been described as inhibitors of the immune response in various inflammatory settings. We show here that patients with concurrent natural helminth infections and MS condition (HIMS) had an increased expression of the negative regulatory TAM receptors in antigen-presenting cells and their agonist GAS6 in circulating CD11bhigh and CD4+ T cells compared to patients with only MS. The Th17 subset was reduced in patients with HIMS with a subsequent downregulation of its pathogenic genetic program. Moreover, these CD4+ T cells promoted lower levels of the co-stimulatory molecules CD80, CD86, and CD40 on dendritic cells compared with CD4+ T cells from patients with MS, an effect that was GAS6-dependent. IL-10+ cells from patients with HIMS showed higher GAS6 expression levels than Th17 cells, and inhibition of phosphatidylserine/GAS6 binding led to an expansion of Th17 effector genes. The addition of GAS6 on activated CD4+ T cells from patients with MS restrains the Th17 gene expression signature. This cohort of patients with HIMS unravels a promising regulatory mechanism to dampen the Th17 inflammatory response in autoimmunity.

Transcriptional regulation of adaptive and innate lymphoid lineage specification.

Once alerted to the presence of a pathogen, activated CD4+ T cells initiate distinct gene expression programs that produce multiple functionally specialized T helper (Th) subsets. The cytokine milieu present at the time of antigen encounter instructs CD4+ T cells to differentiate into interferon-(IFN)-γ-producing Th1 cells, interleukin-(IL)-4-producing Th2 cells, IL-17-producing Th17 cells, follicular T helper (Tfh) cells, or regulatory T (Treg) cells. In each of these Th cell subsets, a single transcription factor has been identified as a critical regulator of its specialized differentiation program. In this context, the expression of the "master regulator" is necessary and sufficient to activate lineage-specific genes while restricting the gene expression program of alternative Th fates. Thus, the transcription factor T-bet controls Th1 differentiation program, while the development of Th2, Th17, Tfh, and Treg cells is dependent on transcription factors GATA3, RORγt, Bcl6, and Foxp3, respectively. Nevertheless, master regulators or, more precisely, lineage-defining transcription factors do not function in isolation. In fact, they interact with a complex network of transcription factors, orchestrating cell lineage specification programs. In this review, we discuss the concept of the combinatorial interactions of key transcription factors in determining helper T cell identity. Additionally, lineage-defining transcription factors have well-established functions beyond their role in CD4+ Th subsets. They play critically important functions at distinct stages during T cell development in the thymus and they control the development of innate lymphoid cells (ILCs) in the bone marrow. In tracking the journey of T cells traversing from the thymus to the periphery and during the immune response, we discuss in broad terms developmental stage and context-dependent functions of lineage-defining transcription factors in regulating specification programs of innate and adaptive lymphocytes.

IL-27 regulates IL-4-induced chemokine production in human bronchial epithelial cells

IL-4 coordinates the Th2-type immune response in inflammatory diseases such as asthma. IL-27 can inhibit the development of both Th2 and Th1 cells. However, IL-27 can also drive naïve T cells to differentiate toward the Th1 phenotype. In this study, we investigated the effects of IL-27 on the activation of IL-4-induced human bronchial epithelial cells (BEAS-2B). Compared to controls, both IL-4 and IL-27 (25–100 ng/mL) increased the concentrations of CCL2 and IL-8 in a dose-dependent manner. However, compared to cells stimulated individually with IL-4 or IL-27, treatment with a combination of both cytokines reduced CCL2 and IL-8 concentrations in a dose- and time-dependent manner. IL-4 increased the activation of p38 MAPK, ERK1/2, STAT6 and NF-κB, while IL-27 increased the activation of p38 MAPK and ERK1/2 but not STAT6 and NF-κB. Compared to IL-4-stimulated cells, cells treated with both IL-27 and IL-4 displayed decreased activation of STAT6 and NF-κB but not ERK1/2 and p38 MAPK. Taken together, these results suggest that IL-27 plays a pro-inflammatory role when administered alone but downregulates bronchial epithelial cell activation when combined with IL-4. Therefore, IL-27 may be an interesting target for the treatment of Th2 inflammatory diseases.

PAF-R on activated T cells: Role in the IL-23/Th17 pathway and relevance to multiple sclerosis

IL-23 is a potent stimulus for Th17 cells. These cells have a distinct developmental pathway from Th1 cells induced by IL-12 and are implicated in autoimmune and inflammatory disorders including multiple sclerosis (MS). TGF-β, IL-6, and IL-1, the transcriptional regulator RORγt (RORC) and IL-23 are implicated in Th17 development and maintenance. In human polyclonally activated T cells, IL-23 enhances IL-17 production.The aims of our study were: 1). To validate microarray results showing preferential expression of platelet activating factor receptor (PAF-R) on IL-23 stimulated T cells. 2). To determine whether PAF-R on activated T cells is functional, whether it is co-regulated with Th17-associated molecules, and whether it is implicated in Th17 function. 3). To determine PAF-R expression in MS.We show that PAF-R is expressed on activated T cells, and is inducible by IL-23 and IL-17, which in turn are induced by PAF binding to PAF-R. PAF-R is co-expressed with IL-17 and regulated similarly with Th17 markers IL-17A, IL-17F, IL-22 and RORC. PAF-R is upregulated on PBMC and T cells of MS patients, and levels correlate with IL-17 and with MS disability scores. Our results show that PAF-R on T cells is associated with the Th17 phenotype and function.Clinical Implications Targeting PAF-R may interfere with Th17 function and offer therapeutic intervention in Th17-associated conditions, including MS.

Abstract IA02: Immune exhaustion and suppression in lymphoma

Abstract The tumor microenvironment in lymphoproliferative disorders, including lymphoma, shows a prevalence of intratumoral T cells suggesting an effective immune response to malignant B cells. This supposes that antigen-presenting cells present tumor-associated peptides to the immune system, resulting in T cells that are primed to target the malignant clone. It is anticipated that activated T cells will target the malignant cells and eradicate the tumor. However, while T cells appear plentiful in the tumor microenvironment in B-cell lymphoma, they are not able to eradicate the malignancy. Rather, the T cells appear inhibited, either due to immune suppression or immune exhaustion, and the lymphoma steadily progresses. An effective antitumor response requires presentation of tumor antigens to T cells in the context of major histocompatibility complex (MHC) proteins. The cells then receive a second activating signal resulting in proliferation of the T cells, expansion of a tumor-specific T-cell clone, and generation of cytotoxic proteins that lyse the lymphoma cell. To control this process, however, inhibitory receptors are typically upregulated upon T-cell activation that allow the process to be suppressed. This prevents damage to healthy tissue from T cells that remain inappropriately activated for protracted periods of time. In lymphoid malignancies, however, malignant B cells commonly overexpress the ligands for PD-1, namely PD-L1 and PD-L2. This results in suppression of the activated T cells and prevents the malignant clone from being eradicated. This leads to a subsequent problem, in which effector T cells are restimulated by the persistent presence of malignant cells that expressed tumor antigens which they are targeting. This repeat stimulation results in activation-induced exhaustion and upregulation of additional receptors that make the cells susceptible to apoptosis. These receptors, including TIM3, TIGIT, and LAG3, are then expressed on T cells whose effector function is severely impaired. The effector T cells expressing TIM3 and LAG3 have very little ability to proliferate or generate cytokines. Additional mechanisms that inhibit T-cell activation are present in lymphoma and include cytokine- and cell-mediated suppression. Among cytokines that mediate T-cell suppression, TGF-β plays a pivotal role in regulating immune responses by inhibiting the proliferation and differentiation in both CD4+ and CD8+ T cells. In B-cell malignancies, both malignant B cells and intratumoral T cells can synthesize and secrete TGF-β, and TGF-β inhibits intratumoral T-cell proliferation, upregulates Foxp3 expression, and suppresses the development of TH1 and TH17 cells. Similarly, IL-10 also inhibits the proliferation, cytokine production, and migratory capacities of T cells. IL-10 downregulates expression of MHC class II as well as costimulatory molecules CD80 and CD86 on dendritic cells, resulting in suboptimal stimulation of T cells. Furthermore, IL-10-expressing dendritic cells promote T regulatory cell development. In B-cell NHL, it has been shown that serum IL-10 levels are elevated and correlate with a poor prognosis. IL-10 further affects monocytes by downregulating HLA-DR expression, and IL-10-induced CD14+HLA-DRlow/- monocytes inhibit T-cell activation and proliferation. In addition to regulatory cytokines, cell-mediated suppression plays a crucial role in T-cell suppression. Myeloid-derived suppressor cells (MDSCs) and CD4+ regulatory T cells are two major types of cells mediating T-cell suppression. In B-cell NHL, increased numbers of MDSCs may contribute to elevated absolute monocytosis at diagnosis that correlates with poor outcome in In DLBCL patients. Tumor-infiltrating MDSCs promote cross-tolerance in B-cell lymphoma by expanding or recruiting regulatory T cells, which supports tumor growth. Regulatory T cells also suppress immune function. In B-cell NHL, we have found that the frequency of regulatory T cells is increased in biopsy specimens. Regulatory T cells suppress proliferation and cytokine production of intratumoral CD4+ cells as well as granule secretion by CD8+ T cells, resulting in suppressed cytotoxicity of effector T cells. We found that both recruitment of naturally occurring regulatory T cells and induction of inducible regulatory T cells contribute to elevated frequency of these cells in the tumor microenvironment of B-cell NHL. Furthermore, malignant B cells play a role in the recruitment and induction of regulatory T cells as chemokine CCL22 secreted by lymphoma cells and CD70 expression by CD19+ lymphoma cells are involved in the process. All of these mechanisms that result in T-cell suppression and exhaustion prevent an effective antitumor immune response in lymphoma. Combination strategies that both activate T cells and prevent their inhibition and suppression are needed to rectify these issues. Citation Format: Stephen M. Ansell. Immune exhaustion and suppression in lymphoma [abstract]. In: Proceedings of the AACR Virtual Meeting: Advances in Malignant Lymphoma; 2020 Aug 17-19. Philadelphia (PA): AACR; Blood Cancer Discov 2020;1(3_Suppl):Abstract nr IA02.

Substance P blocks ovariectomy-induced bone loss by modulating inflammation and potentiating stem cell function.

Osteoporosis is an age-related disease caused by imbalanced bone remodeling resulting from excessive bone resorption. Osteoporosis is tightly linked with induction of chronic inflammation, which activates osteoclasts and impairs osteoprogenitor in bone marrow. T helper 17 (Th17) cells have been recently recognized as one of major inducers in the pathophysiology of bone loss by secreting IL-17. Thus, modulation of Th17 development is anticipated to affect the progression of osteoporosis.Substance P (SP) is reported to provide anti-inflammatory effects by controlling immune cell profile and also, promote restoration of damaged stem cell niches—the bone marrow—by repopulating BMSCs or potentiating its paracrine ability. This study aimed to explore the therapeutic effects of systemically injected SP on ovariectomy (OVX)-induced osteoporosis.Resultantly, SP injection obviously blocked OVX-induced impairment of bone microarchitecture and reduction of the mineral density. In osteoporotic condition, SP could ameliorate chronic inflammation by promoting Treg cell polarization and inhibiting the development of osteoclastogenic Th17 cells. Moreover, SP could rejuvenate stem cell and enable stem cells to repopulate and differentiate into osteoblast.Collectively, our study strongly suggests that SP treatment can block osteoporosis and furthermore, SP treatment provides therapeutic effect on chronic disease with inflammation and stem cell dysfunction.

Th17-inducing autologous dendritic cell vaccination promotes antigen-specific cellular and humoral immunity in ovarian cancer patients

In ovarian cancer (OC), IL-17-producing T cells (Th17s) predict improved survival, whereas regulatory T cells predict poorer survival. We previously developed a vaccine whereby patient-derived dendritic cells (DCs) are programmed to induce Th17 responses to the OC antigen folate receptor alpha (FRα). Here we report the results of a single-arm open-label phase I clinical trial designed to determine vaccine safety and tolerability (primary outcomes) and recurrence-free survival (secondary outcome). Immunogenicity is also evaluated. Recruitment is complete with a total of 19 Stage IIIC-IV OC patients in first remission after conventional therapy. DCs are generated using our Th17-inducing protocol and are pulsed with HLA class II epitopes from FRα. Mature antigen-loaded DCs are injected intradermally. All patients have completed study-related interventions. No grade 3 or higher adverse events are seen. Vaccination results in the development of Th1, Th17, and antibody responses to FRα in the majority of patients. Th1 and antibody responses are associated with prolonged recurrence-free survival. Antibody-dependent cell-mediated cytotoxic activity against FRα is also associated with prolonged RFS. Of 18 patients evaluable for efficacy, 39% (7/18) remain recurrence-free at the time of data censoring, with a median follow-up of 49.2 months. Thus, vaccination with Th17-inducing FRα-loaded DCs is safe, induces antigen-specific immunity, and is associated with prolonged remission.

Function and mechanism of histone demethytransferase Jmjd3 mediated regulation of Th1/Th2 balance through epigenetic modification in pre-eclampsia

Objective: To observe the expression level of histone demethyltransferase Jmjd3 in patients with pre-eclampsia (PE), and to investigate the possible mechanism of its epigenetic modification in regulating Th1/Th2 imbalance in PE patients. Methods: The mRNA levels of histone demethyltransferase Jmjd3 from peripheral blood mononuclear cells (PBMC) of PE patients and normal pregnant women were detected by RT-PCR. Peripheral serum IFN-γ and IL-4 were detected by ELISA. RT-PCR was used to detect the mRNA levels of Jmjd3, Tbx21 and Cxcr3 in the spleen of PE and control mice. Immunomagnetic beads were used to sort out the initial CD4+ T cells in the spleen of control and PE mice. Western blot was used to detect H3K27me1 and H3K27me3 levels. ChIP analysis was used for H3K27me3 demethylation modification in spleens of PE mice. Results: Compared with normal pregnant women, the mRNA level of Jmjd3 in PBMC of PE patients was significantly increased, the level of IFN-γ in serum was significantly increased, and the level of IL-4 was significantly reduced (P<0.01). Compared with normal control mice, the mRNA level of Jmjd3 in the spleen of PE mice was significantly increased, and the expression of Tbx21 and Cxcr3 was significantly increased in PE mice (P<0.01); the H3K27me3 level of CD4+ T cells in PE mice was significantly reduced (P<0.05), but H3K27me1 was not changed. ChIP analysis showed that CD4+ T cells H3K27me3 in PE group mice were in the Ifng promoter region, compared with control mice. Recruitment was significantly reduced, while recruitment in the promoter region of Il4 was significantly increased (P<0.01). Conclusions: In both PE patients and mice with PE model, the relative expression level of histone demethyltransferase Jmjd3 is significantly up-regulated, which further induces the demethylation of H3K27me3 in the Ifng promoter region and promotes the initial CD4+ T cells to Th1 cell differentiation and development, leading to an imbalance of Th1/Th2, which may be one of the important reasons for the development of preeclampsia.

Lower T Regulatory and Th17 Cell Populations Predicted by RT-PCR-Amplified FOXP3 and RORγt Genes Are Not Rare in Patients With Primary Immunodeficiency Diseases.

Deficiencies in T regulatory (Treg) and Th17 cells attenuate peripheral tolerance and the IL-17 family of cytokines, contributing to autoimmune disorders and opportunistic (fungal) infections, respectively. Because of limited blood samples from patients with primary immunodeficiency diseases (PIDs), a positive correlation/linear relationship between Treg and Th17 cells and their respective expressions of transcription factors forkhead box P3 (FOXP3) and retinoic acid-related orphan receptor γ (RORγt) by real-time PCR (RT-PCR) amplification, was used to predict the percentages of Treg and Th17 cells in peripheral blood. Compared to glyceraldehyde 3-phosphate dehydrogenase (GAPDH) expression, the percentages of Treg and Th17 cells were calculated as the linear relationship to the 2−ΔCT value (cycle threshold). Among 91 PIDs patients, 68 and 78 had predicted Treg and Th17 percentages below 5% of the normal ranges (0.859 and 0.734%, respectively), which expanded different categories beyond obvious T cell deficiency. Notably, FOXP3 was undetectable in one patient (CVID), RORγt was undetectable in six patients (one CVID, one CID, two neutropenia, one WAS, and one CMC), and both were undetectable in four patients (two SCID, one STAT1, and one periodic fever). In contrast, two patients with auto-IFNγ antibodies had increased susceptibility to intracellular mycobacterial infections, interrupted Th1 development and subsequent elevation in the Th17 cells. Both predicted Treg and Th17 percentages in the PIDs patients were more independent of age (months) than in the controls. The predicted Th17/Treg ratio in the PIDs patients, overall, was lower than that in the healthy controls (0.79 ± 0.075 vs. 1.16 ± 0.208; p = 0.038). In conclusion, lower predicted Treg and Th17 cell populations calculated by RT-PCR-amplified FOXP3 and RORγt in PIDs patients at diagnosis can explain the higher potential phenotypes of autoimmune disorders and opportunistic infections, although effective interventions in the early stage might have prevented such phenotypic development and caused a statistical bias in the comparisons.

MicroRNA-155 Deficiency Exacerbates Trypanosoma cruzi Infection.

Chagas disease, caused by the intracellular protozoan parasite Trypanosoma cruzi, is a public health problem affecting 6 to 8 million people, mainly in Latin America. The role of microRNAs in the pathogenesis of Chagas disease has not been well described. Here, we investigate the role of microRNA-155 (miR-155), a proinflammatory host innate immune regulator responsible for T helper type 1 and type 17 (Th1 and Th17) development and macrophage responses during T. cruzi infection. For this, we compared the survival and parasite growth and distribution in miR-155-/- and wild-type (WT) C57BL/6 mice. The lack of miR-155 caused robust parasite infection and diminished survival of infected mice, while WT mice were resistant to infection. Immunological analysis of infected mice indicated that, in the absence of miR-155, there was decreased interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α) production. In addition, we found that there was a significant reduction of CD8-positive (CD8+) T cells, natural killer (NK) cells, and NK-T cells and increased accumulation of neutrophils and inflammatory monocytes in miR-155-/- mice. Collectively, these data indicate that miR-155 is an important immune regulatory molecule critical for the control of T. cruzi infection.

Tnfaip3 expression in pulmonary conventional type 1 Langerin-expressing dendritic cells regulates T helper 2-mediated airway inflammation in mice.

BackgroundConventional type 1 dendritic cells (cDC1s) control anti‐viral and anti‐tumor immunity by inducing antigen‐specific cytotoxic CD8+ T‐cell responses. Controversy exists whether cDC1s also control CD4+ T helper 2 (Th2) cell responses, since suppressive and activating roles have been reported. DC activation status, controlled by the transcription factor NF‐κB, might determine the precise outcome of Th‐cell differentiation upon encounter with cDC1s. To investigate the role of activated cDC1s in Th2‐driven immune responses, pulmonary cDC1s were activated by targeted deletion of A20/Tnfaip3, a negative regulator of NF‐κB signaling.MethodsTo target pulmonary cDC1s, Cd207 (Langerin)‐mediated excision of A20/Tnfaip3 was used, generating Tnfaip3 fl/flxCd207 +/cre (Tnfaip3 Lg‐KO) mice. Mice were exposed to house dust mite (HDM) to provoke Th2‐mediated immune responses.ResultsMice harboring Tnfaip3‐deficient cDC1s did not develop Th2‐driven eosinophilic airway inflammation upon HDM exposure, but rather showed elevated numbers of IFNγ‐expressing CD8+ T cells. In addition, Tnfaip3 Lg‐KO mice harbored increased numbers of IL‐12–expressing cDC1s and elevated PD‐L1 expression in all pulmonary DC subsets. Blocking either IL‐12 or IFNγ in Tnfaip3 Lg‐KO mice restored Th2 responses, whereas administration of recombinant IFNγ during HDM sensitization in C57Bl/6 mice blocked Th2 development.ConclusionsThese findings indicate that the activation status of cDC1s, shown by their specific expression of co‐inhibitory molecules and cytokines, critically contributes to the development of Th2 cell–mediated disorders, most likely by influencing IFNγ production in CD8+ T cells.

IgE-mediated regulation of IL-10 and type I IFN enhances rhinovirus-induced Th2 differentiation by primary human monocytes.

Rhinovirus (RV) infections are linked to the development and exacerbation of allergic diseases including allergic asthma. IgE, another contributor to atopic disease pathogenesis, has been shown to regulate DC antiviral functions and influence T cell priming by monocytes. We previously demonstrated that IgE-mediated stimulation of monocytes alters multiple cellular functions including cytokine secretion, phagocytosis, and influenza-induced Th1 development. In this study, we investigate the effects of IgE-mediated stimulation on monocyte-driven, RV-induced T cell development utilizing primary human monocyte-T cell co-cultures. We demonstrate that IgE crosslinking of RV-exposed monocytes enhances monocyte-driven Th2 differentiation. This increase in RV-induced Th2 development was regulated by IgE-mediated inhibition of virus-induced type I IFN and induction of IL-10. These findings suggest an additional mechanism by which two clinically significant risk factors for allergic disease exacerbations-IgE-mediated stimulation and rhinovirus infection-may synergistically promote Th2 differentiation and allergic inflammation.

Exposure of Intestinal Epithelial Cells to 2'-Fucosyllactose and CpG Enhances Galectin Release and Instructs Dendritic Cells to Drive Th1 and Regulatory-Type Immune Development.

Intestinal epithelial cells (IEC) release immunomodulatory galectins upon exposure to CpG DNA (mimicking bacterial triggers) and short-chain galacto- and long-chain fructo-oligosaccharides (GF). This study aims to investigate the immunomodulatory properties of 2′-fucosyllactose (2′-FL), a non-digestible oligosaccharide (NDO) abundantly present in human milk, using a co-culture model developed to study the crosstalk between IEC and innate and adaptive immune cells. IECs, co-cultured with αCD3/CD28-activated peripheral blood mononuclear cells (PBMC), were apically exposed to NDOs and CpG, washed and co-cultured with immature monocyte-derived dendritic cells (moDC). Subsequently, moDC were co-cultured with naïve CD4+ T-cells. In the presence of CpG, both 2′-FL or GF-exposed IEC enhanced Th1-type IFNγ and regulatory IL-10 secretion of PBMCs, compared to CpG alone, while Th2-type IL-13 was reduced. Both NDOs increased IEC-derived galectin-3, -4, -9 and TGF-β1 of CpG-exposed IEC. Only galectin-9 correlated with all modified immune parameters and TGF-β1 secretion. MoDCs exposed to 2′-FL and CpG-conditioned IEC instructed IFNγ and IL-10 secretion by CD4+ T-cells, suggesting the development of a regulatory Th1 response. These results reveal that 2′-FL and GF could contribute to the mucosal immune development by supporting the effect of microbial CpG DNA associated with the modulation of epithelial galectin and TGF-β1 secretion.

Commentary on: The potency of lncRNA MALAT1/miR-155 in altering asthmatic Th1/Th2 balance by modulation of CTLA4.

Asthma is a common, allergic respiratory disorder affecting over 350 million people worldwide. One of the key features of asthma is skewing of CD4+ cells toward Th2 responses. This promotes the production of cytokines like IL-4 that induce IgE production resulting in the hypersecretion of mucus and airway smooth muscle contraction. Understanding the factors that favor Th2 expansion in asthma would provide important insights into the underlying pathogenesis of this disorder. Asthma research has focused on signaling pathways that control the transcription of key asthma-related genes. However, increasing evidence shows that post-transcriptional factors also determine CD4+ cell fate and the enhancement of allergic airway responses. A recent paper published by Liang et al. (Bioscience Reports (2020) 40, https://doi.org/10.1042/BSR20190397) highlights a novel role for the long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in Th2 development in asthma. MALAT1 modulates several biological processes including alternative splicing, epigenetic modification and gene expression. It is one of the most highly expressed lncRNAs in normal tissues and MALAT1 levels correlate with poor clinical outcomes in cancer. The mechanisms of action of MALAT1 in tumor progression and metastasis remain unclear and even less is known about its effects in inflammatory disease states like asthma. The work of Liang et al. demonstrates heightened MALAT1 expression in asthma and further shows that this lncRNA targets miR-155 to promote Th2 differentiation in this disease. This insight sets the stage for future studies to examine how MALAT1 manipulation could deter allergic immune responses in asthmatic airways.

The Regulatory Role of PIRB in CD4+ Th17 Mediated Colitis

Abstract Rationale CD4+T-cell differentiation into effector or memory populations is intrinsically regulated by the delicate balance between activating and inhibitory signals. Previously we identified a role of the inhibitory receptor, Paired Immunoglobulin-like Receptor (PIR) B in the negative regulation of innate immune responses in colitis. The aim of this study is to define the involvement of PIRB in CD4+ Th17 development and regulation of CD4+ Th17-dependent colitis. Results We demonstrate an intrinsic deficiency in PirB−/− Th17 in vitro polarization and cell survival. Specifically, polyclonal activation of PirB−/− Th17 cells lead to increased cell death and enhanced caspase activation (# of Dead cells, WT vs PirB−/−: 17.6 ± 2.3 × 103 vs 38.5 ± 5.8 × 103; # of Caspase 3/7+ cells: 9.8 ± 1.8 × 102 vs 19.7 ± 1.2 × 102; mean ± SEM, p &amp;lt; 0.05). In vivo, PirB−/− Il10−/− mice were protected from development of Il10−/− spontaneous colitis phenotype (Clinical Score, Il10−/− vs PirB−/− Il10−/−: 3.3 ± 0.6 vs 0.14 ± 0.08, p &amp;lt; 0.01; Histological Score: 2.3 ± 0.4 vs 1.2 ± 0.2; mean ± SEM, p &amp;lt; 0.01) and this was associated with reduced CD4+ Th17 cells in the mesenteric lymph nodes (% IL-17a+ cells, Il10−/− vs PirB−/− Il10−/−: 2.5 ± 0.3 vs 1.2 ± 0.1; mean ± SEM, p &amp;lt; 0.001). To test the intrinsic effects to the CD4+ T-cell compartment, we performed the CD4+ CD45RBhi T-cell transfer model of colitis. Rag−/− mice which received PirB−/− naïve CD4+ T-cells were protected from T-cell mediated colitis (% Change in Body Weight: −3.5 ± 4.9 % WT; 20.7 ± 4.6 % PirB−/−; p &amp;lt; 0.001; Histological Score: 3.8 ± 0.2 WT; 1.0 ± 0.4 PirB−/−; mean ± SEM, p &amp;lt; 0.001). Conclusions These data support the concept that PIRB regulates CD4+ Th17 differentiation and development of T-cell-dependent colitis phenotype.

STAT4 promotes critical neutrophil functions and is required for antimicrobial immunity in mice

Abstract Signal transducer and activator of transcription 4 (STAT4) is a transcription factor mainly associated with Th1 development, yet its role in neutrophil biology is unknown. We are the first to demonstrate that in vitro murine neutrophils stimulated with IL-12 directly activate STAT4 in a JAK2-dependent manner resulting in distinct transcriptional changes in antimicrobial response genes. STAT4-deficiency also impairs several neutrophil functions in vitro. Interestingly, IL-12 directly induces STAT4-dependent ROS formation at 14 hours, which is not due to cell death. Neutrophil extracellular trap (NET) formation in response to either LPS or heat-killed Pseudomonas aeruginosa results in decreased nuclear translocation of myeloperoxidase, decreased neutrophil elastase release, and decreased DNA release in STAT4-deficient neutrophils. In vivo neutrophil migration to the peritoneal cavity is blunted in Stat4−/− mice following either thioglycollate, CXCL1, or GM-CSF injections. Finally, we have generated Stat4floxLysMCre and Stat4floxS100A8Cre mice which are deficient in STAT4 in either myeloid cells or specifically neutrophils, respectively. Following in vivo infection with methicillin-resistant S. aureus, bacterial burden is increased in the blood and peritoneal cavity of Stat4floxLysMCre and Stat4floxS100A8Cre mice. Gene expression analysis of peritoneal exudate cells from infected mice show decreased expression of Ly6G/CD11b, further highlighting defective homing of Stat4−/− neutrophils in vivo. All together these data reveal an undiscovered role of STAT4 in neutrophil functions and a subsequent role of STAT4 in innate immunity and antimicrobial defense mechanisms.

NK cells provide DC-mediated ‘help’ in cellular immunity to HIV

Abstract Natural killer (NK) cells are uniquely positioned to positively impact antiviral immunity to HIV-1 due to the pleiotropic nature of their effector functions, including the ability to respond directly to infected cells and to translate environmental cues into functional ‘help’ for other immune cells. In particular, their interplay with dendritic cells (DCs) is powerful in shaping the quality and character of the adaptive immune response. In this study, we explored the ‘helper’ function of NK cells in response to both innate and adaptive stimuli in chronic HIV-1 infection. Freshly isolated NK cells from virally suppressed HIV-1 seropositive individuals were co-cultured for 48h with autologous monocyte-derived immature DCs in the presence or absence of innate stimuli or opsonized target cells. Responding NK cells were assessed for their ability to produce DC-modulating cytokines; DCs harvested from the co-cultures were analyzed for their expression of maturation-associated surface markers, as well as their subsequent ability to produce IL-12p70 and to drive type 1 immunity. DC-derived co-stimulatory factors efficiently activated the ‘helper’ function of NK cells as evidenced by their robust production of IFNγ. Opsonizing antibodies also synergized with IFNα to promote NK ‘helper’ cell activity. Furthermore, interactions between NK cells and DCs induced the development of mature DCs with a heightened ability to produce IL-12p70 and to drive the development of Th1 and cytotoxic T cell responses. Our data demonstrate the capacity of NK cells to enhance DC-mediated immune responses to HIV-1 and, thus, highlight the potential for harnessing the reciprocal crosstalk between NK cells and DCs in the design of novel anti-HIV-1 therapies.