TGF-β1-induced regulatory T cells

Polyclonally Derived Alloantigen-Specific T Regulatory Cells Exhibit Target-Specific Suppression and Capture MHC Class II from Dendritic Cells

Foxp3+ T regulatory (Treg) cells prevent allograft rejection and graft-versus-host disease. Although polyclonal Tregs have been used both in animal models and in humans, the fine specificity of their suppressive function is poorly defined. We have generated mouse recipient-derived alloantigen-specific Tregs in vitro and explored the fine specificity of their suppressive function and their mechanism of action in vitro and in vivo. In vitro, when alloantigen and peptide Ag were both presented on the same dendritic cell, both responses were suppressed by iTregs specific either for the alloantigen or for the peptide Ag. In vivo, iTreg suppression was limited to the cognate Ag, and no bystander suppression was observed when both allo-antigen and peptide Ag were present on the same dendritic cell. In vitro, alloantigen-specific Tregs captured cognate MHC but failed to capture noncognate MHC. Our results demonstrate that a polyclonal population of iTregs generated from naive T cells can mediate highly specific function in vivo and support the view that Treg therapy, even with unselected polyclonal populations, is likely to be target antigen-specific and that bystander responses to self-antigens or to infectious agents are unlikely.

Exploring the therapeutic potential of regulatory T cell in rheumatoid arthritis: Insights into subsets, markers, and signaling pathways

Rheumatoid arthritis (RA) is a complex autoimmune inflammatory rheumatic disease characterized by an imbalance between immunological reactivity and immune tolerance. Regulatory T cells (Tregs), which play a crucial role in controlling ongoing autoimmunity and maintaining peripheral tolerance, have shown great potential for the treatment of autoimmune inflammatory rheumatic diseases such as RA. This review aims to provide an updated summary of the latest insights into Treg-targeting techniques in RA. We focus on current therapeutic strategies for targeting Tregs based on discussing their subsets, surface markers, suppressive function, and signaling pathways in RA.

Intricacies of TGF-β signaling in Treg and Th17 cell biology

Balanced immunity is pivotal for health and homeostasis. CD4+ helper T (Th) cells are central to the balance between immune tolerance and immune rejection. Th cells adopt distinct functions to maintain tolerance and clear pathogens. Dysregulation of Th cell function often leads to maladies, including autoimmunity, inflammatory disease, cancer, and infection. Regulatory T (Treg) and Th17 cells are critical Th cell types involved in immune tolerance, homeostasis, pathogenicity, and pathogen clearance. It is therefore critical to understand how Treg and Th17 cells are regulated in health and disease. Cytokines are instrumental in directing Treg and Th17 cell function. The evolutionarily conserved TGF-β (transforming growth factor-β) cytokine superfamily is of particular interest because it is central to the biology of both Treg cells that are predominantly immunosuppressive and Th17 cells that can be proinflammatory, pathogenic, and immune regulatory. How TGF-β superfamily members and their intricate signaling pathways regulate Treg and Th17 cell function is a question that has been intensely investigated for two decades. Here, we introduce the fundamental biology of TGF-β superfamily signaling, Treg cells, and Th17 cells and discuss in detail how the TGF-β superfamily contributes to Treg and Th17 cell biology through complex yet ordered and cooperative signaling networks.

A, Gota V, Goda JS. Insight into lipid-based nanoplatform-mediated drug and gene delivery in neuro-oncology and their clinical prospects

Tumors of the Central nervous System (CNS) are a spectrum of neoplasms that range from benign lesions to highly malignant and aggressive lesions. Despite aggressive multimodal treatment approaches, the morbidity and mortality are high with dismal survival outcomes in these malignant tumors. Moreover, the non-specificity of conventional treatments substantiates the rationale for precise therapeutic strategies that selectively target infiltrating tumor cells within the brain, and minimize systemic and collateral damage. With the recent advancement of nanoplatforms for biomaterials applications, lipid-based nanoparticulate systems present an attractive and breakthrough impact on CNS tumor management. Lipid nanoparticles centered immunotherapeutic agents treating malignant CNS tumors could convene the clear need for precise treatment strategies. Immunotherapeutic agents can selectively induce specific immune responses by active or innate immune responses at the local site within the brain. In this review, we discuss the therapeutic applications of lipid-based nanoplatforms for CNS tumors with an emphasis on revolutionary approaches in brain targeting, imaging, and drug and gene delivery with immunotherapy. Lipid-based nanoparticle platforms represent one of the most promising colloidal carriers for chemotherapeutic, and immunotherapeutic drugs. Their current application in oncology especially in brain tumors has brought about a paradigm shift in cancer treatment by improving the antitumor activity of several agents that could be used to selectively target brain tumors. Subsequently, the lab-to-clinic transformation and challenges towards translational feasibility of lipid-based nanoplatforms for drug and gene/immunotherapy delivery in the context of CNS tumor management is addressed.

Injury-induced interleukin-1 alpha promotes Lgr5 hair follicle stem cells de novo regeneration and proliferation via regulating regenerative microenvironment in mice

BACKGROUND

The hair follicles (HFs) are barely regenerated after loss in injuries in mammals as well as in human beings. Recent studies have shown that the regenerative ability of HFs is age-related; however, the relationship between this phenomenon and the stem cell niche remains unclear. This study aimed to find a key secretory protein that promotes the HFs regeneration in the regenerative microenvironment.

METHODS

To explore why age affects HFs de novo regeneration, we established an age-dependent HFs regeneration model in leucine-rich repeat G protein-coupled receptor 5 (Lgr5) + /mTmG mice. Proteins in tissue fluids were analyzed by high-throughput sequencing. The role and mechanism of candidate proteins in HFs de novo regeneration and hair follicle stem cells (HFSCs) activation were investigated through in vivo experiments. The effects of candidate proteins on skin cell populations were investigated by cellular experiments.

RESULTS

Mice under 3-week-old (3W) could regenerate HFs and Lgr5 HFSCs, which were highly correlated with the immune cells, cytokines, IL-17 signaling pathway, and IL-1α level in the regeneration microenvironment. Additionally, IL-1α injection induced de novo regeneration of HFs and Lgr5 HFSCs in 3W mouse model with a 5 mm wound, as well as promoted activation and proliferation of Lgr5 HFSCs in 7-week-old (7W) mice without wound. Dexamethasone and TEMPOL inhibited the effects of IL-1α. Moreover, IL-1α increased skin thickness and promoted the proliferation of human epidermal keratinocyte line (HaCaT) and skin-derived precursors (SKPs) in vivo and in vitro, respectively.

CONCLUSIONS

In conclusion, injury-induced IL-1α promotes HFs regeneration by modulating inflammatory cells and oxidative stress-induced Lgr5 HFSCs regeneration as well as promoting skin cell populations proliferation. This study uncovers the underlying molecular mechanisms enabling HFs de novo regeneration in an age-dependent model.

BMP2 as a promising anticancer approach: functions and molecular mechanisms

Bone morphogenetic protein 2 (BMP2), a pluripotent factor, is a member of the transforming growth factor-beta (TGF-β) superfamily and is implicated in embryonic development and postnatal homeostasis in tissues and organs. Experimental research in the contexts of physiology and pathology has indicated that BMP2 can induce macrophages to differentiate into osteoclasts and accelerate the osteolytic mechanism, aggravating cancer cell bone metastasis. Emerging studies have stressed the potent regulatory effect of BMP2 in cancer cell differentiation, proliferation, survival, and apoptosis. Complicated signaling networks involving multiple regulatory proteins imply the significant biological functions of BMP2 in cancer. In this review, we comprehensively summarized and discussed the current evidence related to the modulation of BMP2 in tumorigenesis and development, including evidence related to the roles and molecular mechanisms of BMP2 in regulating cancer stem cells (CSCs), epithelial-mesenchymal transition (EMT), cancer angiogenesis and the tumor microenvironment (TME). All these findings suggest that BMP2 may be an effective therapeutic target for cancer and a new marker for assessing treatment efficacy.

The positive feedback loop of furin and TGFβ1 enhances the immune responses of Tregs to hepatocellular carcinoma cells and hepatitis B virus in vitro

Regulatory T cells (Tregs) can exert immunosuppressive activity. Furin can regulate Treg functions, hepatitis B virus (HBV) persistent infection, and hepatocellular carcinoma (HCC) development. However, it remains unknown whether furin can regulate the immune responses of Tregs to HBV and HCC cells. Here, coculture systems of HBV1.3P-HepG2.3P-HepG2 cells and Tregs transduced with or without lentiviral particles that could overexpress furin or knockdown furin/transforming growth factor β1 (TGFβ1) were established to investigate the regulatory relationship between furin and TGFβ1 and the effect of furin/TGFβ1 on Treg activity. Also, the effects of furin overexpression or furin/TGFβ1 knockdown in Tregs on the immunological activity of effector T cells (Teffs)/cytotoxic T lymphocytes (CTLs) and HBV replication/expression were explored in the coculture system of Teff/CTL, Treg, and HBV1.3P-HepG2 cells. Our results showed that furin expression and TGFβ1 secretion were notably increased in Tregs, and Furin and TGFβ1 formed a positive feedback loop to activate Tregs in the coculture system of Tregs and HBV1.3P-HepG2 cells. Furin or TGFβ1 knockdown in Tregs promoted Teff cell proliferation, stimulated interleukin-2 and interferon-γ secretion, and inhibited HBV replication/gene expression in the coculture system of Teff, Treg, and HBV1.3P-HepG2 cells. Moreover, furin or TGFβ1 depletion in Tregs enhanced the killing activity of CTLs against HBV1.3P-HepG2 cells and curbed HBV replication/gene expression in the coculture system of Tregs, CTLs, and HBV1.3P-HepG2 cells. In conclusion, the positive feedback loop of furin and TGFβ1 enhanced the immune responses of Tregs to HCC cells and HBV in vitro.

Anti-tuberculosis chemotherapy alters TNFR2 expression on CD4+ lymphocytes in both drug-sensitive and -resistant tuberculosis: however, only drug-resistant tuberculosis maintains a pro-inflammatory profile after a long time

Background

Tuberculosis (TB) is an infectious disease. During TB, regulatory T cells (Treg) are related to poor prognosis. However, information about conventional and unconventional Treg (cTreg and uTreg, respectively) is limited. The tumour necrosis factor (TNF) and its receptors (TNFR1 and TNFR2) are necessary for mycobacterial infection, and TNFR2 signalling is required to maintain Treg.

Methods

A blood sample of drug-susceptible (DS-TB) and drug-resistant tuberculosis (DR-TB) patients was obtained before (basal) and after 2 and 6 months of anti-TB therapy. Expression of TNF, TNFR1, and TNFR2 (transmembrane form, tm) on cTreg, uTreg, activated CD4+ (actCD4+), and CD4+ CD25− (CD4+) T cell subpopulations were evaluated. The main objective was to identify immunological changes associated with sensitive/resistant Mtb strains and with the use of anti-TB therapy.

Results

We found that after 6 months of anti-TB therapy, both DS- and DR-TB patients have decreased the frequency of cTreg tmTNF+, CD4+ tmTNFR1+ and CD4+ tmTNFR2+. Nevertheless, after 6 months of therapy, only DR-TB patients decreased the frequency of actCD4+ tmTNF+ and actCD4+ tmTNFR2+, exhibited a systemic inflammatory status (high levels of TNF, IFN-γ and IL-12), and their purified CD4+ T cells showed that TNF and TNFR2 are up-regulated at the transcriptional level. Moreover, DS- and DR-TB down-regulated TNFR1 and other proteins associated with Treg (FOXP3 and TGFβ1) in response to the anti-TB therapy.

Conclusion

These results partially explain the differences in the immune response of DS-TB vs DR-TB. The frequency of actCD4+ tmTNFR2+ cells and inflammatory status should be considered in the follow-up of therapy in DR-TB patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00320-4.

Epithelial cell-derived CD83 restores immune tolerance in the airway mucosa by inducing regulatory T-cell differentiation

The mechanism of generation of regulatory T cells (Treg) remains incompletely understood. Recent studies show that CD83 has immune regulatory functions. This study aims to investigate the role of epithelial cell-derived CD83 in the restoration of immune tolerance in the airway mucosa by inducing the Treg differentiation. In this study, CD83 and ovalbumin (OVA)-carrying exosomes were generated from airway epithelial cells. An airway allergy mouse model was developed to test the role of CD83/OVA-carrying exosomes in the suppression of airway allergy by inducing Treg generation. We observed that mouse airway epithelial cells expressed CD83 that could be up-regulated by CD40 ligand. The CD83 deficiency in epithelial cells retarded the Treg generation in the airway mucosa. CD83 up-regulated transforming growth factor-β-inducible early gene 1 expression in CD4+ T cells to promote Foxp3 expression. Exposure of primed CD4+ T cells to CD83/OVA-carrying exosomes promoted antigen-specific Treg generation. Administration of CD83/OVA-carrying exosomes inhibited experimental airway allergic response. In summary, airway epithelial cells express CD83 that is required in the Treg differentiation in the airway mucosa. Administration of CD83/OVA-carrying exosomes can inhibit airway allergy that has the translation potential in the treatment of airway allergic disorders.

Immunological discrepancy in aged mice facilitates skin allograft survival

More and more aged people are undergoing organ transplantation. Understanding aging effects on immunity will be helpful for post-transplantation care and adjustment of immunosuppressants for aged recipients. A mouse model, using C3H mice as donors and aged/young C57BL/10J mice as recipients, was employed to study aging effects on immunity. The results showed that frequency of myeloid-derived suppressor cells (MDSC) and level of TGF-β was higher in aged mice than in young mice (4.4 ± 1.4% versus 1.6 ± 1.1%, p = 0.026 for MDSC; 21.04 ± 3.91 ng/ml versus 15.26 ± 5.01 ng/ml, p = 0.026 for TGF-β). In vivo, skin allograft survived longer on the aged than on young mice (19.7 ± 5.2 days versus 11.9 ± 4.1 days, p = 0.005). When entinostat was applied to block MDSC, the survival of skin allografts on aged mice was shorten to 13.5 ± 4.7 days which was not different from the survival on young mice (p = 0.359). In conclusion, allogeneic immunity was different in aged from young mice in high frequency of MDSC and high serum level of TGF-β. Blocking the function of MDSC reversed the low immunity in aged mice and caused skin allograft rejection similar to young recipients.

Poly(ADP-ribose) polymerase-1 inhibitor ameliorates dextran sulfate sodium-induced colitis in mice by regulating the balance of Th17/Treg cells and inhibiting the NF-κB signaling pathway

Poly(ADP-ribose) polymerase-1 (PARP-1) plays a critical role in inflammatory pathways. The PARP-1 inhibitor, 5-aminoisoquinolinone (5-AIQ), has been demonstrated to exert significant pharmacological effects. The present study aimed to further examine the potential mechanisms of 5-AIQ in a mouse model of dextran sodium sulfate (DSS)-induced colitis. Colitis conditions were assessed by changes in weight, disease activity index, colon length, histopathology and pro-inflammatory mediators. The colonic expression of PARP/NF-κB and STAT3 pathway components was measured by western blot analysis. Flow cytometry was used to analyze the proportion of T helper 17 cells (Th17) and regulatory T cells (Tregs) in the spleen. Western blot analysis and reverse transcription-quantitative PCR were employed to determine the expression of the transcription factors retinoic acid-related orphan receptor and forkhead box protein P3. The results demonstrated that 5-AIQ reduced tissue damage and the inflammatory response in mice with experimental colitis. Moreover, 5-AIQ increased the proportion of Treg cells and decreased the percentage of Th17 cells in the spleen. Furthermore, following 5-AIQ treatment, the main components of the PARP/NF-κB and STAT3 pathways were downregulated. Collectively, these results demonstrate that the PARP-1 inhibitor, 5-AIQ, may suppress intestinal inflammation and protect the colonic mucosa by modulating Treg/Th17 immune balance and inhibiting PARP-1/NF-κB and STAT3 signaling pathways in mice with experimental colitis.

Effects of butyric acid, a bacterial metabolite, on the migration of ameloblastoma mediated by laminin 332

Ameloblastoma is a benign tumor that develops in the jawbone. Occasionally, however, it may become malignant and metastasize to other tissues. Although it has been suggested that various cytokines and several adhesion factors may play a role in its malignant transformation, the details have not been elucidated. In this context, it has been reported that butyric acid produced by periodontopathic bacteria causes progression of malignant tumors occurring in the mouth via podoplanin. However, the influence of butyric acid on ameloblastoma has not been clarified. In the present study, therefore, the expression of various cytokines and adhesion factors in ameloblastoma upon stimulation with butyric acid or cytokines was investigated using real-time reverse-transcription polymerase chain reaction. Three cell lines (HAM1, HAM2 and HAM3) established from the same ameloblastoma were used in the experiments. It was found that the expression of mRNAs for epidermal growth factor (EGF) and transforming growth factor beta 1 (TGFβ1) was increased in HAM2 and HAM3, respectively, upon stimulation with butyric acid. In addition, stimulation with EGF and TGFβ1 led to an increase in the expression of laminin β-3 mRNA in the respective cell lines. These results suggest that butyric acid may be involved in ameloblastoma exacerbation through the expression of laminin 332 (LM332) via EGF and TGFβ1 produced by ameloblastoma itself.

HLA-G Expressing Immune Cells in Immune Mediated Diseases

HLA-G is a HLA class Ib antigen that possesses immunomodulatory properties. HLA-G-expressing CD4+ and CD8+ T lymphocytes, NK cells, monocytes, and dendritic cells with immunoregulatory functions are present in small percentages of patients with physiologic conditions. Quantitative and qualitative derangements of HLA-G+ immune cells have been detected in several conditions in which the immune system plays an important role, such as infectious, neoplastic, and autoimmune diseases as well as in complications from transplants and pregnancy. These observations strongly support the hypothesis that HLA-G+ immune cells may be implicated in the complex mechanisms underlying the pathogenesis of these disorders.

CXCL4 promoted the production of CD4+CD25+FOXP3+treg cells in mouse sepsis model through regulating STAT5/FOXP3 pathway

Background: CXCL4 plays an essential role in the regulation of multiple immune diseases. However, the underlying role of CXCL4 is still not clear in sepsis. Aim: In the present study, we aimed to investigate the function of CXCL4 in sepsis.Methods: Sepsis model was constructed on mouse. Flow cytometry was used to determine the ratio of CD4⁺CD25⁺FOXP3⁺Treg cells. ELISA assays were used to determine the levels of CXCL4, IL-6, IL-10, and TNF-α respectively. Western blot was used to examine protein contents.Results: Our results suggested that the serum level of CXCL4 was upregulated in patients with sepsis and positively associated with the ratio of human CD4⁺CD25⁺FOXP3⁺Treg cells. To further examine the role of CXCL4 in sepsis, we constructed the mouse sepsis model. Our results indicated that the mouse antibody of CXCL4 treatment reduced the expression of urine creatinine and urea nitrogen in sepsis model. Moreover, the frequency of CD25⁺FOXP3⁺ mouse regulatory T cells (Tregs) cells was decreased in mouse CD4⁺ T cells in the presence of mouse CXCL4 antibody. Further, the mouse recombinant protein CXCL4 was used to culture normal mouse CD4⁺ T cells in vitro. Our finding indicated that the recombinant protein CXCL4 promoted the percentage of mouse CD25⁺FOXP3⁺Treg cells and enhanced the phosphorylation of STAT5 in mouse CD4⁺ T cells in a dose-dependent manner. However, these effects were significantly reversed by the STAT5 inhibitor (p < .001). Conclusion: our findings not only indicated the function and signalling pathway of CXCL4 in CD4⁺ T cells but also provided novel insight and target in sepsis treatment.

CARsomes inhibit airway allergic inflammation in mice by inducing antigen-specific Th2 cell apoptosis

BACKGROUND

Skewed T helper (Th)2 response plays a crucial role in the pathogenesis of allergic diseases. The therapeutic efficacy for allergic diseases is unsatisfactory currently. This study aims to regulate the skewed Th2 response with CARsomes.

METHODS

The CARsome consisted of an epitope of Dermatophagoides farina-1 (Derf1), a segment of the anti-DEC205 antibody, the scFv, and an open reading frame of perforin. This fusion protein binds to DEC205 molecule on the surface of exosomes derived from dendritic cells (DC). The effects of CARsome on inducing antigen (Ag)-specific Th2 cell apoptosis were assessed both in vivo and in vitro.

RESULTS

Exposure to CARsomes in the culture induced Ag-specific Th2 cell apoptosis. Injection of CARsomes through the vein puncture also induced Ag-specific Th2 cell apoptosis in the lungs of sensitized mice. CARsomes could induce Ag-specific regulatory T cells. Administration of CARsomes efficiently inhibited experimental allergic airway inflammation.

CONCLUSIONS

The CARsomes can inhibit allergic airway inflammation by inducing Ag-specific Th2 cell apoptosis and induce Ag-specific regulatory T cells. The data suggest that CARsomes have the translational potential to be used to treat allergic airway inflammation.

Transforming growth factor beta 1 levels in the blood of pediatric liver recipients: Clinical and biochemical correlations

TGF-β1 is a cytokine with profibrogenic and immunosuppressive activities, which suggest the clinical significance of TGF-β1 for the assessment of graft function after LT. We analyzed the dynamics of TGF-β1 levels in the blood after LDLT in 135 pediatric liver recipients and examined the relationship between the cytokine levels and the laboratory and clinical variables. We found that TGF-β1 levels in the blood of patients with ESLD were lower than that in healthy children of the same age, P = .001. Moreover, blood levels of TGF-β1 were associated with liver disease etiology (r = .23) and hepatic fibrosis severity (r = .33). Before LDLT, TGF-β1 levels were significantly higher in children with good outcomes than in recipients who developed graft dysfunction early in the post-transplant period, P = .047. One month after LDLT, TGF-β1 levels in blood plasma increased in pediatric recipients, P = .002. Cytokine levels were significantly correlated with gender (r = .21) and HLA (r = -.24) mismatches, as well as with TAC dosage (r = -.32) later in the post-transplant period. One year after LDLT, TGF-β1 plasma levels were higher (P = .01) than those before LDLT and did not correlate with most of the investigated biochemical and clinical variables. Conclusion: Blood levels of TGF-β1 are associated with hepatic fibrosis severity, graft dysfunction development, and TAC dosage and can be regarded as a potential prognostic biomarker for the assessment of graft function and the optimization of immunosuppressant dosage in pediatric recipients after LDLT.

Negligible Effect of Sodium Chloride on the Development and Function of TGF-β-Induced CD4+ Foxp3+ Regulatory T Cells

High-salt diets inhibit the suppressive function of thymus-derived natural regulatory T cells (tTreg). Transforming growth factor β (TGF-β)-induced ex vivo regulatory T cells (iTreg) comprise another Treg subset that exhibits similarities and differences with tTreg. Here, we demonstrate that iTregs are completely stable and fully functional under high salt conditions. High salt does not influence the development, differentiation, and functional activities of iTreg but affects Foxp3 stability and function of tTreg in vitro and in vivo. In addition, high salt does not significantly change the transcription profiles of the iTreg signature or pro-inflammatory genes. Therefore, we conclude that iTreg, unlike tTreg, are stable and functional in the presence of high salt. Our findings provide additional evidence that iTreg may have different biological features from tTreg and suggest a greater potential for clinical utility in patients with autoimmune diseases, in which the complicated role of environmental factors, including diet, must be considered.

The wonders of BMP9: From mesenchymal stem cell differentiation, angiogenesis, neurogenesis, tumorigenesis, and metabolism to regenerative medicine

Although bone morphogenetic proteins (BMPs) initially showed effective induction of ectopic bone growth in muscle, it has since been determined that these proteins, as members of the TGF-β superfamily, play a diverse and critical array of biological roles. These roles include regulating skeletal and bone formation, angiogenesis, and development and homeostasis of multiple organ systems. Disruptions of the members of the TGF-β/BMP superfamily result in severe skeletal and extra-skeletal irregularities, suggesting high therapeutic potential from understanding this family of BMP proteins. Although it was once one of the least characterized BMPs, BMP9 has revealed itself to have the highest osteogenic potential across numerous experiments both in vitro and in vivo, with recent studies suggesting that the exceptional potency of BMP9 may result from unique signaling pathways that differentiate it from other BMPs. The effectiveness of BMP9 in inducing bone formation was recently revealed in promising experiments that demonstrated efficacy in the repair of critical sized cranial defects as well as compatibility with bone-inducing bio-implants, revealing the great translational promise of BMP9. Furthermore, emerging evidence indicates that, besides its osteogenic activity, BMP9 exerts a broad range of biological functions, including stem cell differentiation, angiogenesis, neurogenesis, tumorigenesis, and metabolism. This review aims to summarize our current understanding of BMP9 across biology and the body.

Molecular and functional characterization of the indoleamine 2,3-dioxygenase in grass carp (Ctenopharyngodon idella)

Indoleamine 2,3-dioxygenase (IDO) is a kind of dioxygenase that can catalyze the degradation of levo-tryptophan (L-Trp) and plays key roles in immune tolerance. In this study, the IDO gene was cloned and functionally characterized from grass carp (gcIDO). The results showed that gcIDO overexpressed in GCO cells could catalyze the degradation of L-Trp through the L-Trp - kynurenine pathway, and this activity could be promoted by δ-aminolevulinic acid (ALA) while inhibited by levo-1-methyl tryptophan (L-1MT). Moreover, gcIDO was constitutively expressed in various tissues, and its expression could be significantly up-regulated by LPS and Poly (I:C) in peripheral blood leukocytes (PBLs). Furthermore, recombinant TGF-β1 of grass carp could up-regulate the expression of IDO, TGF-β1, CD25, and Foxp3 in PBLs, indicating that the TGF-β1/IDO pathway is present in fish. In the soybean meal induced enteritis (SBMIE) model, the expression of gcIDO in the intestine was up-regulated significantly, demonstrating that gcIDO may play an immunoregulatory role in SBMIE. Taken together, these data suggest that the IDO plays multiple roles in the immunity of fish.

Frontline Science: TLR3 activation inhibits food allergy in mice by inducing IFN-γ+ Foxp3+ regulatory T cells

The pathologic feature of food allergy (FA) is the aberrant Th2-biased immune response in the intestine. Regulatory T cells (Tregs) play an important role in the suppression of aberrant immune response. The activities of the TLRs regulate multiple cell functions. This study aims to investigate the role of TLR3 activation in the regulation of Th2-biased immune response in the intestine by the generation of inducible Tregs (iTregs). In this study, polyinosinic polycytidylic acid (polyI:C) was used as an activator of TLR3. An FA mouse model was developed to establish the Th2-biased inflammation in the intestine. The effects of TLR3 activation on the generation of iTreg were tested in the culture and in mice. We observed that exposure to polyI:C induced IFN-γ⁺ Foxp3⁺ iTregs in mouse intestine and in the culture. The IFN-γ⁺ Foxp3⁺ iTregs showed immune suppressive functions. Exposure to polyI:C increased T-bet levels in CD4⁺ T cells. The T-bet formed a complex with GATA3 to dissociate Foxp3 from GATA3/Foxp3 complex in CD4⁺ T cells. The Foxp3 thus gained the opportunity to move to TGF-β promoter to generate iTregs. Administration with polyI:C prevented the development of FA and inhibited existing FA. In conclusion, activation of TLR3 induces IFN-γ⁺ Foxp3⁺ Tregs, which can prevent FA development and inhibit existing FA in mice.

CEP128 is a crucial risk locus for autoimmune thyroid diseases

Autoimmune thyroid disease (AITD) mainly includes Graves' disease (GD) and Hashimoto's thyroiditis (HT), and its pathogenesis is not clearly defined. This study was designed to explore risk loci for AITD. Genome-wide genetic data were analyzed to identify important risk loci for GD, and a case-control study with 845 AITD patients and 694 healthy controls was also conducted. The functional role of possible risk loci for GD was explored by analyzing the correlations of Centrosomal protein 128 (CEP128) expression level with intrathyroidal immune cells and key genes for candidate immune cells in GD thyroid tissues. CEP128 was identified as an important risk locus for GD in the genome-wide genetic analysis, and it was located near TSHR without obvious linkage disequilibrium with TSHR. Two tag single-nucleotide variants in CEP128 including a missense variant rs327463 were substantially related to genetic predisposition to GD and HT in the case-control study. CEP128 rs327463 was substantially related to GD under the allele model (OR = 1.31, 95%CI 1.08-1.59, P = 0.006) and the dominant model (OR = 1.37, 95%CI 1.09-1.72, P = 0.008), and it was related to HT under the recessive model (OR = 1.85, P = 0.031) and the homozygous model (OR = 1.91, P = 0.025). Moreover, CEP128 was substantially correlated with the frequencies of T-follicular helper (Tfh) cell and M1 macrophages in GD tissues. Gene set enrichment analysis suggested that CEP128 was related to several common immune pathways involved in GD pathogenesis, such as interferon-γ mediated signaling pathway and toll-like receptor signaling pathway. This study highlight the crucial role of CEP128 in the pathogenesis of GD, and polymorphisms in CEP128 contribute to genetic predisposition to both GD and HT.

The Role of the Status of Selected Micronutrients in Shaping the Immune Function

OBJECTIVE

This narrative review gives an overview on the essential role of adequate nutrition to an optimally functioning immune defence. Micronutrients act as regulators of the immune response, with the focus of this review on the immunomodulatory effects of the trace elements iron, zinc and selenium, and the vitamins A, D, E, C, B6 and B12 and folic acid.

RESULTS

Iron deficiency especially impairs the Th1 cell-borne cellular immunity. T lymphocytes are also most affected by a deficiency of zinc, needed for their maturation and the balance between the different T cell subpopulations and acting as a redox signal in the regulation of many enzymes. Selenium is also involved in redox reactions as the glutathione peroxidases and other redox enzymes are selenoproteins. Selenium status has shown special effects on cellular immunity and resistance to viral infections. Vitamin A in the form of retinoic acid induces a humoral Th2 cell response via antigen-presenting cells and is involved in maintaining intestinal immune defence and tolerance through its nuclear receptor RAR and via kinase signalling cascades. Immune tolerance is particularly promoted by vitamin D acting through dendritic cells to stimulate the differentiation of regulatory T cells. Vitamin E has antiinflammatory effects and stimulates naïve T cells especially in the elderly. Besides its antioxidative properties, vitamin C has effects on cell signalling and epigenetic regulation. The B vitamins are required for cytotoxic cellular immunity and modulate T cell responses.

CONCLUSION

A diverse diet and regular exposure to sunlight are the best sources for a balanced nutrient supply to maintain an optimal immune defence.

Glucocorticoid hormone differentially modulates the in vitro expansion and cytokine profile of thymic and splenic Treg cells

OBJECTIVE

Functional disturbances in regulatory T cells (Treg) have been described in autoimmune diseases, and their potential therapeutic use is intensively studied. Our goal was to investigate the influence of glucocorticoid hormone on the in vitro differentiation of Treg cells from thymic and splenic CD4⁺ T cells under different conditions to establish methods for generating stable and functionally suppressive iTregs for future use in adoptive transfer experiments.

METHODS

Thymic and splenic CD4⁺ T lymphocytes were isolated from 3 to 4 week-old control and in vivo dexamethasone (DX) pretreated BALB/c mice using magnetic bead negative selection, followed by CD25 positive selection. The cells were cultured with anti-CD3/CD28 beads and IL-2 in the presence or absence of TGFβ and/or DX for 3-6 days. Multiparametric flow cytometry was performed using CD4, CD25, CD8, TGFβ (LAP) cell surface and Foxp3, IL-4, IL-10, IL-17 and IFNγ intracellular staining. Quantitative RT-PCR was performed to measure IL-10, TGFβ cytokine and Foxp3 mRNA levels.

RESULTS

Differentiation of thymus-derived CD4⁺ cells in vitro into iTreg cells was most effective (24-25%) when anti-CD3/CD28 beads, IL-2, and TGFβ were present. Splenic CD4⁺ T cell expansion under same conditions resulted in a higher (44-45%) iTreg cell ratio that further increased (up to 50% Treg) in the presence of DX. Elevated immunosuppressive cytokine (IL-10 and TGFβ) production by iTregs could be measured both at protein and mRNA levels without elevation of Th1/Th2 or Th17 cytokine production. We got the highest iTreg ratio (74%) and TGFβ production when CD4⁺CD25⁺ splenic T cells were stimulated in the presence of TGFβ. In vivo 4 days DX pretreatment resulted in enhanced in vitro expansion and Foxp3 expression of thymus-derived iTregs and decreased differentiation of spleen-derived iTreg cells. In these Tregs the relative expression of IL-10 mRNA significantly decreased under all in vitro stimulation conditions, while TGFβ mRNA level did not change.

CONCLUSION

DX promotes the expansion of thymic and splenic Treg cells, and enhances Foxp3⁺ expression and the production of immunosuppressive cytokines IL-10 and TGFβ in vitro. In vivo pretreatment of mice with DX inhibited the immunosuppressive cytokine production of in vitro differentiated Treg cells. We hypothesize that patients receiving GC therapy may need special attention prior to in vitro expansion and transplantation of Treg cells.

ImmTAC/Anti-PD-1 antibody combination to enhance killing of cancer cells by reversing regulatory T-cell-mediated immunosuppression

Recently, bi-functional molecules that can redirect immune effectors to tumour cells have emerged as potentially robust mediators of tumour regression in clinical trials. Two modalities in particular, bi-specific antibodies for T-cell redirection and activation (BiTe) and immune-mobilizing monoclonal T-cell receptors against cancer (ImmTAC), are being evaluated in efficacy studies as 'off-the-shelf' reagents. Optimal therapy will require an understanding and means to address regulatory mechanisms of limiting efficacy. In light of this, we evaluated the impact of induced regulatory T (iTreg) cells on the efficacy of tumour cell killing redirected by ImmTAC and demonstrated down-regulation of T-cell proliferation and expression of CD25, CD107a, Granzyme B and Perforin by ImmTAC-redirected T cells. Significant recovery of ImmTAC potency, however, could be achieved when combined with an anti-programmed cell death protein 1 monoclonal antibody. Furthermore, we found that among lung cancer patients failing to respond to ImmTAC therapy, there was a significantly higher fraction of Treg cells in the peripheral blood mononuclear cells of lung cancer patients than in healthy donors. These results provide in vitro evidence for an iTreg cell-mediated immunosuppression of ImmTAC-redirected T-cell responses. Whilst immune checkpoint blockade can reverse the Treg cell suppression, it forms a rational basis for a combination of the blockade with ImmTAC in clinical trials.

Serum Levels of IL-6, IL-8, TNF-α, and TGF-β in Chronic HBV-Infected Patients: Effect of Depression and Anxiety

Objective

To assess the effects of depression and anxiety on serum cytokine levels in patients with chronic hepatitis B (CHB) infection.

Methods

In this cross-sectional study, 60 healthy control individuals and 60 patients with CHB participated after filling out standard questionnaires. We examined their serum interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α, and TGF-β levels using enzyme-linked immunosorbent assay (ELISA) techniques.

Results

In patients with CHB compared with healthy controls, serum levels of IL-8 were significantly increased, whereas IL-6 and TGF-β levels were significantly decreased. Serum levels of TGF-β were significantly decreased in the patients with CHB who had mild depression, compared with patients with CHB without depression and with moderate and severe depression.

Conclusions

Downregulation of IL-8 and TGF-β, respectively, is a corresponding mechanism for induction of chronic inflammation in patients with CHB. Depression also seems to induce inflammation via downregulation of TGF-β in these patients.

Regulatory T-Cells Mediate IFN-α-Induced Resistance against Antigen-Induced Arthritis

Objective

CD4⁺FoxP3⁺CD25⁺ regulatory T-cells (T_regs) are important for preventing tissue destruction. Here, we investigate the role of T_regs for protection against experimental arthritis by IFN-α.

Methods

Arthritis was triggered by intra-articular injection of methylated bovine serum albumin (mBSA) in wild-type mice, Foxp3DTReGFP^+/− mice [allowing selective depletion of T_regs by diphtheria toxin (DT)] and CD4-Cre^+/− IFNA1R flox/flox mice (devoid of IFNAR signaling in T-cells) earlier immunized with mBSA, with or without treatment with IFN-α or the indoleamine 2,3-dioxygenase (IDO)-metabolite kynurenine. T_regs were depleted in DT-treated Foxp3DTReGFP^+/− mice and enumerated by FoxP3 staining. Suppressive capacity of FACS-sorted CD25^+highCD4⁺ T_regs was tested in vivo by adoptive transfer and ex vivo in cocultures with antigen-stimulated CFSE-stained T-responder (CD25⁻CD4⁺) cells. IDO was inhibited by 1-methyl tryptophan.

Results

Both control mice and mice devoid of IFNAR-signaling in T helper cells were protected from arthritis by IFN-α. Depletion of T_regs in the arthritis phase, but not at immunization, abolished the protective effect of IFN-α and kynurenine against arthritis. IFN-α increased the number of T_regs in ex vivo cultures upon antigen recall stimulation but not in naïve cells. IFN-α also increased the suppressive capacity of T_regs against mBSA-induced T-responder cell proliferation ex vivo and against arthritis when adoptively transferred. The increased suppressive activity against proliferation conferred by IFN-α was clearly reduced by in vivo inhibition of IDO at immunization, which also abolished the protective effect of IFN-α against arthritis.

Conclusion

By activating IDO during antigen sensitization, IFN-α activates T_regs, which prevent arthritis triggered by antigen rechallenge. This is one way by which IFN-α suppresses inflammation.

The role of Th17 cells in auto-inflammatory neurological disorders

The role of T helper 17 (Th17) cells in auto-inflammatory neurological disorders such as Multiple Sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD) and schizophrenia has not been clarified completely. Th17-derived pro-inflammatory cytokines including IL-17, IL-21, IL-22, IL-23, GM-CSF, and IFN-γ have a critical role in the pathogenesis of these disorders. In this review, we demonstrate the role of Th17 cells and their related cytokines in the immunopathology of above-mentioned disorders to get a better understanding of neuroinflammatory mechanisms mediated by Th17 cells associated with events leading to neurodegeneration.

Greater transforming growth factor-β in adult female SHR is dependent on blood pressure, but does not account for sex differences in renal T-regulatory cells

Female spontaneously hypertensive rats (SHR) have more renal regulatory T cells (Tregs) than males, and greater levels of Tregs in female SHR are dependent on blood pressure (BP). However, the molecular mechanism responsible for greater Tregs in female SHR is unknown. Transforming growth factor (TGF)-β is a pleiotropic cytokine critical in the differentiation of naïve T cells into Tregs, and female SHR have higher TGF-β excretion than male SHR. The goals of the current study were to test the hypotheses that 1) female SHR have greater renal TGF-β expression than male SHR, which is dependent on BP and 2) neutralizing TGF-β will decrease renal Tregs in female SHR. Renal cortices were isolated from 5- and 13-wk-old male and female SHR, and TGF-β levels were measured via Western blot and ELISA. Adult female SHR have more free, active TGF-β₁ than 5-wk-old female SHR (46% more) or male SHR (44% more than 5-wk-old males and 56% more than 13-wk-old male SHR). We confirmed greater TGF-β₁ in adult female SHR was due to increases in BP and not sexual maturation by measuring TGF-β₁ levels following treatment with BP-lowering drugs or ovariectomy. Separate female SHR were treated with an antibody to TGF-β_1,2,3; BP was measured, and T cells were assessed in whole blood and the kidney. Neutralizing TGF-β had no effect on BP, although circulating Tregs decreased by 32%, while Th17 cells increased by 64%. Renal Tregs were not altered by antibody treatment, although Th17 cells were decreased by 61%. In conclusion, although TGF-β promotes circulating Tregs in female SHR, it does not account for the sex difference in renal Tregs in SHR.

TGF-β Affects the Differentiation of Human GM-CSF+ CD4+ T Cells in an Activation- and Sodium-Dependent Manner

The cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) is involved in the pathogenesis of chronic inflammatory diseases such as multiple sclerosis. However, the environmental cues promoting differentiation of GM-CSF producing T cells are unclear. Herein, we performed a broad experimental screening of cytokines and data-driven analysis assessing their ability to induce human GM-CSF⁺ CD4⁺ T cells and their subpopulations. TGF-β was discovered to induce GM-CSF production independently of proliferation and IL-2 signaling including STAT5. In contrast, IL-6 and IL-23 decreased GM-CSF production. On the population level, GM-CSF induction was highly correlated with expression of FOXP3 across cytokine stimulations but not with that of IL-17. However, on single-cell level GM-CSF and IFN-γ expression were most correlated, independently of the cytokine environment. Importantly, under low sodium conditions in the medium or upon stimulation with plate-bound instead of bead-bound anti-CD3 and anti-CD28 antibodies, the effects of TGF-β on GM-CSF, but not on FOXP3, were reversed. Our analysis indicates a novel role for TGF-β in generating GM-CSF⁺ subsets of human CD4⁺ T cells. These results are important for understanding of autoimmune disease and therapeutic considerations.

Screening Immunomodulators To Skew the Antigen-Specific Autoimmune Response

Current therapies to treat autoimmune diseases often result in side effects such as nonspecific immunosuppression. Therapies that can induce antigen-specific immune tolerance provide an opportunity to reverse autoimmunity and mitigate the risks associated with global immunosuppression. In an effort to induce antigen-specific immune tolerance, co-administration of immunomodulators with autoantigens has been investigated in an effort to reprogram autoimmunity. To date, identifying immunomodulators that may skew the antigen-specific immune response has been ad hoc at best. To address this need, we utilized splenocytes obtained from mice with experimental autoimmune encephalomyelitis (EAE) in order to determine if certain immunomodulators may induce markers of immune tolerance following antigen rechallenge. Of the immunomodulatory compounds investigated, only dexamethasone modified the antigen-specific immune response by skewing the cytokine response and decreasing T-cell populations at a concentration corresponding to a relevant in vivo dose. Thus, antigen-educated EAE splenocytes provide an ex vivo screen for investigating compounds capable of skewing the antigen-specific immune response, and this approach could be extrapolated to antigen-educated cells from other diseases or human tissues.

DNA Methyltransferase Inhibitor Promotes Human CD4+CD25hFOXP3+ Regulatory T Lymphocyte Induction under Suboptimal TCR Stimulation

The “master transcription factor” FOXP3 regulates the differentiation, homeostasis, and suppressor function of CD4⁺ regulatory T (Treg) cells, which are critical in maintaining immune tolerance. Epigenetic regulation of FOXP3 expression has been demonstrated to be important to Treg cell development, but the induction of human Treg cells through epigenetic modification has not been clearly described. We report that the combination of the DNA methyltransferase inhibitor 5-azacytidine (5-Aza) and suboptimal T cell receptor (TCR) stimulation promoted CD4⁺CD25^hFOXP3⁺ T cell induction from human CD4⁺CD25⁻ T cells. 5-Aza treatment enhanced the expression of Treg cell signature genes, such as CD25, FOXP3, CTLA-4, and GITR, in CD4⁺CD25^h cells. Moreover, 5-Aza-treated CD4⁺CD25^h T cells showed potent suppressive activity in a cell contact-dependent manner and reduced methylation in the Treg-specific demethylated region (TSDR) in the FOXP3 gene. The analysis of cytokine production revealed that CD4⁺CD25⁻ T cells with 5-Aza treatment produced comparable levels of interferon (IFN)-γ and transforming growth factor (TGF)-β, but less IL-10 and more IL-2, when compared to cells without 5-Aza treatment. The increased IL-2 was indispensible to the enhanced FOXP3 expression in 5-Aza-treated CD4⁺CD25^h cells. Finally, 5-Aza-treated CD4⁺CD25^h T cells could be expanded with IL-2 supplementation alone and maintained FOXP3 expression and suppressor function through the expansion. Our findings demonstrate that DNA demethylation can enhance the induction of human Treg cells and promise to solve one of the challenges with using Treg cells in therapeutic approaches.

IDO1 and TGF-β Mediate Protective Effects of IFN-α in Antigen-Induced Arthritis

IFN-α prevents Ag-induced arthritis (AIA), and in this study we investigated the role of IDO1 and TGF-β signaling for this anti-inflammatory property of IFN-α. Arthritis was induced by methylated BSA (mBSA) in mBSA-sensitized wild-type (WT), Ido1^-/-, or Ifnar^-/- mice, treated or not with IFN-α or the IDO1 product kynurenine (Kyn). Enzymatic IDO1 activity, TGF-β, and plasmacytoid dendritic cells (pDC) were neutralized by 1-methyltryptophan and Abs against TGF-β and pDC, respectively. IDO1 expression was determined by RT-PCR, Western blot, and FACS, and enzymatic activity by HPLC. Proliferation was measured by ³H-thymidine incorporation and TGF-β by RT-PCR and ELISA. WT but not Ido1^-/- mice were protected from AIA by IFN-α, and Kyn, the main IDO1 product, also prevented AIA, both in WT and Ifnar^-/- mice. Protective treatment with IFN-α increased the expression of IDO1 in pDC during AIA, and Ab-mediated depletion of pDC, either during mBSA sensitization or after triggering of arthritis, completely abrogated the protective effect of IFN-α. IFN-α treatment also increased the enzymatic IDO1 activity (Kyn/tryptophan ratio), which in turn activated production of TGF-β. Neutralization of enzymatic IDO1 activity or TGF-β signaling blocked the protective effect of IFN-α against AIA, but only during sensitization and not after triggering of arthritis. Likewise, inhibition of the IDO1 enzymatic activity in the sensitization phase, but not after triggering of arthritis, subdued the IFN-α-induced inhibition of mBSA-induced proliferation. In conclusion, presence of IFN-α at Ag sensitization activates an IDO1/TGF-β-dependent anti-inflammatory program that upon antigenic rechallenge prevents inflammation via pDC.

Programmed cell death protein-1/programmed cell death ligand-1 pathway inhibition and predictive biomarkers: understanding transforming growth factor-beta role

A deeper understanding of the key role of the immune system in regulating tumor growth and progression has led to the development of a number of immunotherapies, including cancer vaccines and immune checkpoint inhibitors. Immune checkpoint inhibitors target molecular pathways involved in immunosuppression, such as cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and programmed cell death protein-1 (PD-1)/programmed cell death ligand-1 (PD-L1) pathway, with the goal to enhance the host's own immune anticancer response. In phase I-III trials, anti-PD-1/PD-L1 antibodies have demonstrated to be effective treatment strategies by inducing significant durable tumor responses, with manageable toxicities, in patients with various malignancies, including those traditionally considered non-immunogenic, such as non-small cell lung cancer (NSCLC). Identification of predictive biomarkers to select patients for immune therapies is currently being investigated to improve their therapeutic efficacy. Transforming growth factor-β (TGF-β), a pleiotropic cytokine with immunosuppressive effects on multiple cell types of the innate and adaptive immune system, has emerged as one of the potential key factors modulating response to immune checkpoint inhibitors. However, due to the complexity of the anti-cancer immune response, the predictive value of many other factors related to cancer cells or tumor microenvironment needs to be further explored.