STAT1 signaling is required for optimal Th1 cell differentiation in mice

CD40L modulates CD4+ T-cell activation through receptor for activated C kinase 1

Inhibition of the co-stimulatory ligand CD40L has shown beneficial effects in many experimental models of autoimmune disease and inflammation. Here, we show that CD40L deficiency in T cells in mice causes a reduction of CD4+ T-cell activation and specifically a strong reduction in IFN-γ-producing Th1 cells. In vitro, we could not reproduce this antigen presenting cell-dependent effects, but found that T-cell CD40L affects cell death and proliferation. We identified receptor of activated C kinase, the canonical PKC binding partner and known to drive proliferation and apoptosis, as a mediator of CD40L reverse signaling. Furthermore, we found that CD40L clustering stabilizes IFN-γ mediated Th1 polarization through STAT1, a known binding partner of receptor of activated C kinase. Together this highlights the importance of both CD40L forward and reverse signaling.

Immunomodulatory Role of Diospyros peregrina Fruit Preparation in Breast Cancer by Utilizing Macrophage Mediated Antigen Presentation and T Helper Cell (Th) Differentiation

BACKGROUND

Diospyros peregrina is dioecious plant native to India and belonging to the family of Ebenaceae, is largely utilized in treatment of various ailments. Little has been known about the antitumor activity of Diospyros peregrina with only 1 previous study on Ehrlich Ascites Carcinoma in mice. Therefore, it prompted us to extensively explore the immunomodulatory effect in various cancer forms. The focal point of this study revolves around breast cancer, which is the second most common cancer in the world. In view of the increasing demands for noninvasive treatments, natural plant-based agents open up promising applications in cancer immunotherapy METHODS: CD4⁺ lymphocytes were isolated from the peripheral blood mononuclear cells (PBMCs) of breast cancer patients and normal donor blood samples using magnetic-activated cell sorting (MACS) and cultured separately. Utilizing the plastic surface adherence property, the macrophages were isolated from CD4 negative lymphocytes of both breast cancer patients and normal donors. For the presentation of tumor antigens invitro, macrophages were pulsed with breast tumor associated antigen (BTAA) in presence or absence of Diospyros peregrina fruit preparation (DFP). Differentially pulsed and irradiated macrophages were co-cultured with autologous and allogenic lymphocytes. Supernatants hence collected from CD4⁺ lymphocytes were utilized for cytokine profiling using ELISA and proliferation was assessed by MTT assay. Cytotoxic T lymphocytes (CTLs) generated from CD4 negative lymphocytes culture (2 × 10⁵) was incubated with MCF-7 (2 × 10⁴) to check cytotoxicity using LDH release assay. CD4⁺ lymphocytes were treated in presence or absence of DFP, were analyzed using immunoblotting and RT-qPCR, to check DFP mediated T helper (Th) cell differentiation through investigation of signatory cytokines and transcription factors.

RESULTS

It was found that DFP elevated the proliferation of CD4⁺ T lymphocytes (Th) in response to BTAA. DFP also helped in presenting BTAA pulsed macrophages directing in the cytotoxic T-lymphocyte mediated immune response. Results indicated that DFP preferentially highlighted Th1 commitment with type-1 specific cytokines IFN-g and IL-12 and was indifferent in Th2 manifestation. DFP was not only involved in the upregulation of Tbet mounted type-1 mediated immune response and activation of STAT1 but also it downregulated STAT6 and GATA3, the functional activators and regulators of type-2 immune response. Moreover, it was observed that DFP inhibited the tumor-promoting environment modulated through Tregs by downregulating Foxp3 and STAT5. Further, it was detected that DFP directs Th1 bias and results in attainment of better suppression of breast tumor CONCLUSION: The results collectively pointed out that DFP favored cell-mediated immune response from BTAA antigen presentation on macrophages and also helping in the robust proliferation of an entire spectrum of T helper lymphocytes which furthermore strengthen the underlying immune responses, hence, fencing the body, of the progression of breast cancer.

Transcriptional inhibition of STAT1 functions in the nucleus alleviates Th1 and Th17 cell-mediated inflammatory diseases

T helper 1 cells (Th1 cells) and T helper 17 cells (Th17 cells) play pivotal roles in the pathogenesis of various autoimmune diseases, including psoriasis and inflammatory bowel disease (IBD). Signal transducer and activator of transcription 1 (STAT1) regulates the Th1 and Th17 cell lineage commitment at an early stage and maintains their immunological functions in vitro and in vivo. The previous strategies to block STAT1 functions to treat autoimmune diseases inhibit Th1 cell activity but simultaneously cause hyper-activation of Th17 cells. Herein, to modulate the functions of pathogenic Th1 and Th17 cells without genetic modification in normal physiological conditions, we generated the nucleus-deliverable form of the transcription modulation domain of STAT1 (ndSTAT1-TMD), which can be transduced into the nucleus of the target cells in a dose- and time-dependent manner without affecting the cell viability and T cell activation signaling events. ndSTAT1-TMD significantly blocked the differentiation of naïve CD4+ T cells into Th1 or Th17 cells via competitive inhibition of endogenous STAT1-mediated transcription, which did not influence Th2 and Treg cell differentiation. When the gene expression profile of Th1 or Th17 cells after ndSTAT1-TMD treatment was analyzed by mRNA sequencing, the expression of the genes involved in the differentiation capacity and the immunological functions of Th1 or Th17 cells were substantially reduced. The therapeutic potential of ndSTAT1-TMD was tested in the animal model of psoriasis and colitis, whose pathogenesis is mainly contributed by Th1 or/and Th17 cells. The symptoms and progression of psoriasis and colitis were significantly alleviated by ndSTAT1-TMD treatment, comparable to anti-IL-17A antibody treatment. In conclusion, our study demonstrates that ndSTAT1-TMD can be a new therapeutic reagent for Th1/17 cell-mediated autoimmune diseases by modulating the functions of pathogenic Th1 and Th17 cells together.

The regulation of T helper cell polarization by the diterpenoid fraction of Rhododendron molle based on the JAK/STAT signaling pathway

The diterpenoid fraction (DF) prepared from fruit of Rhododendron molle was shown to have potential therapeutic effects on collagen-induced arthritis (CIA) rats based on our previous studies. As a continuation of those studies, herein, a lipopolysaccharide-induced endotoxin shock mouse model was used. The results showed that 0.2 mg/ml of DF significantly increased the mouse survival rate and had an anti-inflammatory effect. Further studies showed that DF could decrease the proportion of T helper cells (Th1 and Th17), and increase the proportion of Th2 and regulatory T cells (Tregs). Enzyme-linked immunosorbent assays indicated that DF inhibited the secretion of inflammatory cytokines such as TNF-α, IL-1β, and IL-6; western blotting showed that DF significantly reduced the levels of phosphorylated STAT1 and STAT3. In vitro, DF could dose-dependently inhibit the polarization of naive CD4⁺ T cells to Th1 or Th17 cells. DF at 10 μg/ml could markedly decrease the expression of mRNA encoding IFN-γ and T-bet, and suppress Th1 differentiation by downregulation of the activity of STAT1 and STAT4. Meanwhile, DF at 10 μg/ml remarkably reduced the expression of mRNA encoding IL-17a, IL-17f, and RORγt, and downregulated STAT3 phosphorylation, suggesting that DF could inhibit Th17 differentiation by reducing STAT3 activation. Taken together, DF blocked the JAK/STAT signaling pathway by inhibiting STAT1 and STAT3 phosphorylation, which clarified the important role of JAK/STAT signaling pathway in anti-rheumatoid arthritis.

Inflammasome Contribution to the Activation of Th1, Th2, and Th17 Immune Responses

Inflammasomes are cytosolic polyprotein complexes formed in response to various external and internal stimuli, including viral and bacterial antigens. The main product of the inflammasome is active caspase 1 which proteolytically cleaves, releasing functional interleukin-1 beta (IL-1β) and interleukin-18 (IL-18). These cytokines play a central role in shaping immune response to pathogens. In this review, we will focus on the mechanisms of inflammasome activation, as well as their role in development of Th1, Th2, and Th17 lymphocytes. The contribution of cytokines IL-1β, IL-18, and IL-33, products of activated inflammasomes, are summarized. Additionally, the role of cytokines released from tissue cells in promoting differentiation of lymphocyte populations is discussed.

Polyphenol containing Sargassum horneri attenuated Th2 differentiation in splenocytes of ovalbumin-sensitised mice: involvement of the transcription factors GATA3/STAT5/NLRP3 in Th2 polarization

CONTEXT

Sargassum horneri (Turner) C. Agardh (Sargassaceae) is a brown marine alga used in oriental medicine to treat allergic conditions.

OBJECTIVE

This study clarifies the effect of polyphenol-containing S. horneri ethanol extract (SHE) on T-helper type-2 (Th2) polarisation.

MATERIALS AND METHODS

All mice (BALB/c mice, n = 12) except in the healthy control group were first sensitised with an intraperitoneal injection of ovalbumin (OVA; 20 µg) and alum (2 mg) on Day 0 and Day 14. Similarly, phosphate-buffered saline (PBS) was injected according to the same schedule into the healthy control mice. After the final administration, splenocytes were obtained. OVA sensitised mice were challenged with OVA (100 µg/mL) in the absence or presence (62.5 and 125 µg/mL) of SHE while healthy control group remained untreated.

RESULTS

SHE (0-1000 µg/mL) was not cytotoxic to splenocytes and demonstrated IC50 values of 3.27 and 3.92 mg/mL, respectively, at 24 and 48 h of incubation. SHE suppressed cell proliferation at concentrations ≥62.5 µg/mL. SHE treatment (125 µg/mL) subdued (by 1.8-fold) the population expansion of CD3+CD4+ helper T cells induced by OVA challenge. SHE attenuated the OVA-induced activation of respective transcription factors GATA3 and NLRP3. Simultaneously, highly elevated levels of cytokines interleukin (IL)-4 and IL-5 caused by OVA stimulation were removed completely and IL-13 suppressed by 1.5-fold.

CONCLUSIONS

SHE exhibits Th2 immune suppression under OVA stimulation via GATA3- and NLRP3-dependent IL-4, IL-5, and IL-13 suppression. Therefore, SHE could be therapeutically useful for alleviating the symptoms of allergen-mediated immune diseases.

Metabolites Profiling of Melanoma Interstitial Fluids Reveals Uridine Diphosphate as Potent Immune Modulator Capable of Limiting Tumor Growth

Tumor interstitial fluid (TIF) surrounds and perfuses tumors and collects ions, metabolites, proteins, and extracellular vesicles secreted by tumor and stromal cells. Specific metabolites, accumulated within the TIF, could induce metabolic alterations of immune cells and shape the tumor microenvironment. We deployed a metabolomic approach to analyze the composition of melanoma TIF and compared it to the plasma of C57BL6 mice, engrafted or not with B16-melanoma cells. Among the classes of metabolites analyzed, monophosphate and diphosphate nucleotides resulted enriched in TIF compared to plasma samples. The analysis of the effects exerted by guanosine diphosphate (GDP) and uridine diphosphate (UDP) on immune response revealed that GDP and UDP increased the percentage of CD4+CD25+FoxP3- and, on isolated CD4+ T-cells, induced the phosphorylation of ERK, STAT1, and STAT3; increased the activity of NF-κB subunits p65, p50, RelB, and p52; increased the expression of Th1/Th17 markers including IFNγ, IL17, T-bet, and RORγt; and reduced the expression of IL13, a Th2 marker. Finally, we observed that local administrations of UDP in B16-engrafted C57BL6 mice reduced tumor growth and necrotic areas. In addition, UDP-treated tumors showed a higher presence of MHCIIhi tumor-associated macrophage (TAM) and of CD3+CD8+ and CD3+CD4+ tumor-infiltrating T-lymphocytes (TILs), both markers of anti-tumor immune response. Consistent with this, intra-tumoral gene expression analysis revealed in UDP-treated tumors an increase in the expression of genes functionally linked to anti-tumor immune response. Our analysis revealed an important metabolite acting as mediator of immune response, which could potentially represent an additional tool to be used as an adjuvant in cancer immunotherapy.

The Role of STAT1 in T Helper Cell Differentiation during Breast Cancer Progression

Members of the signal transducer and activator of transcription (STAT) protein family are intracellular transcription factors that facilitate several facets of cellular immunity, proliferation, apoptosis, and differentiation. They are principally stimulated by membrane receptor-associated Janus kinases. Dysregulation of this pathway is often detected in primary tumors and hints at augmented angiogenesis, which enriches tumors persistence and immunosuppression. STAT proteins play indispensable roles in cytokine signaling and T helper (Th) cell differentiation. Among STAT proteins, STAT1 plays a vital role in interferon signaling, which initiates the expression of genes encoding proteins with antitumor and apoptotic roles. STAT1 signaling is essential for Th1 cell differentiation. Several studies have also shown the role of STAT1 as a tumor suppressor in breast cancer, which is the most common intrusive malignancy and the second most common cause of cancer death in women. Herein, we review the intricate STAT1-mediated molecular mechanisms associated with Th cell differentiation and anti-tumor function in breast cancer.

Role of the JAK/STAT Pathway in Cervical Cancer: Its Relationship with HPV E6/E7 Oncoproteins

The janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway is associated with the regulation of essential cellular mechanisms, such as proliferation, invasion, survival, inflammation, and immunity. Aberrant JAK/STAT signaling contributes to cancer progression and metastatic development. STAT proteins play an essential role in the development of cervical cancer, and the inhibition of the JAK/STAT pathway may be essential for enhancing tumor cell death. Persistent activation of different STATs is present in a variety of cancers, including cervical cancer, and their overactivation may be associated with a poor prognosis and poor overall survival. The oncoproteins E6 and E7 play a critical role in the progression of cervical cancer and may mediate the activation of the JAK/STAT pathway. Inhibition of STAT proteins appears to show promise for establishing new targets in cancer treatment. The present review summarizes the knowledge about the participation of the different components of the JAK/STAT pathway and the participation of the human papillomavirus (HPV) associated with the process of cellular malignancy.

IFITM proteins drive type 2 T helper cell differentiation and exacerbate allergic airway inflammation

The interferon‐inducible transmembrane (Ifitm/Fragilis) genes encode homologous proteins that are induced by IFNs. Here, we show that IFITM proteins regulate murine CD4⁺ Th cell differentiation. Ifitm2 and Ifitm3 are expressed in wild‐type (WT) CD4⁺ T cells. On activation, Ifitm3 was downregulated and Ifitm2 was upregulated. Resting Ifitm‐family‐deficient CD4⁺ T cells had higher expression of Th1‐associated genes than WT and purified naive Ifitm‐family‐deficient CD4⁺ T cells differentiated more efficiently to Th1, whereas Th2 differentiation was inhibited.

Ifitm‐family‐deficient mice, but not Ifitm3‐deficient mice, were less susceptible than WT to induction of allergic airways disease, with a weaker Th2 response and less severe disease and lower Il4 but higher Ifng expression and IL‐27 secretion. Thus, the Ifitm family is important in adaptive immunity, influencing Th1/Th2 polarization, and Th2 immunopathology.