Treg Responses Research Articles

The role of S-nitrosoglutathione reductase (GSNOR) in T cell-mediated immunopathology of experimental autoimmune encephalomyelitis (EAE)

Previously, we reported that both S-nitrosoglutathione (GSNO), a carrier of cellular nitric oxide, and N6022, an injectable form of GSNO reductase (GSNOR) inhibitor that increases endogenous GSNO levels, alleviate experimental autoimmune encephalomyelitis (EAE) in mice by suppressing Th1 and Th17 immune responses. Building on these findings, we explored the role of GSNOR in EAE pathogenesis and evaluated the efficacy of an orally active GSNOR inhibitor (N91115) in treating the EAE disease. EAE mice exhibited heightened expression/activity of GSNOR in the spinal cord, and the knockout of the GSNOR gene resulted in much milder clinical manifestations of EAE, with lower degrees of demyelination and axonal loss, reduced microglial and astrocyte activations, as well as suppressed Th1 and Th17 cell responses, alongside bolstered Treg immune responses. Next, we evaluated the efficacy of N91115 against EAE immunopathology. Consistent with our findings in GSNOR deficient EAE mice, daily N91115 administration reduced clinical EAE severity, with less spinal cord demyelination and axonal loss compared to untreated EAE mice. Furthermore, N91115 treated EAE mice showed diminished Th1 and Th17 immune responses and enhanced Treg responses. This observation underscores the potential of increased GSNOR expression and activity as a risk factor exacerbating EAE immunopathology, while simultaneously highlighting its potential as a target for modifying the disease. Furthermore, the balanced immune regulation provided by orally active N91115 (IL-6/IL-17a vs. IL-10) presents a promising alternative to immunosuppressive drugs, reducing the risk of opportunistic infections.

PI3 kinase delta governs regulatory T-cell biology and thus confers protection against atherosclerosis progression in mice

Abstract Introduction and Purpose Atherosclerosis is a chronic inflammatory disease of arteries, critically involving innate and adaptive immune cells like macrophages as well as T and B lymphocytes. Macrophages are major drivers of disease through the ingestion of lipoproteins, foam cell formation, and secretion of inflammatory mediators. Although macrophages outnumber other leukocytes in atherosclerotic plaques, T and B cells can shape the course of disease by promoting or mitigating inflammatory responses. The phosphoinositide 3-kinase delta (PI3Kd) exerts a key role in the regulation of immune responses including activation, proliferation, differentiation, and effector function of lymphocytes. Therefore, PI3Kd may represent a promising target for the modulation of inflammatory diseases. Consequently, we aimed to analyse the role of PI3Kd during atherogenesis. Methods and Results To investigate the role of haematopoietic PI3Kd in atherosclerosis, bone marrow from PI3Kd-/- or PI3Kd+/+ mice was transplanted into Ldlr-/- mice. After a 6-weeks-challenge by high fat diet, PI3Kd-/- recipient Ldlr-/- mice displayed profoundly impaired CD4+ and CD8+ T-cell numbers, CD4+ T-cell activation, CD4+ effector T-cell differentiation, and proatherogenic CD4+ T-helper (Th) 1 responses in para-aortic lymph nodes and spleen compared with PI3Kd+/+ transplanted controls. Surprisingly, the net effect of PI3Kd deficiency was a substantial increase of aortic inflammation and atherosclerosis in Ldlr-/- mice. Whereas plaque content and functions of macrophages including foam cell formation, efferocytosis, and cytokine secretion remained largely unaffected, haematopoietic PI3Kd ablation strongly reduced mature B cells and serum immunoglobulins in Ldlr-/- mice. Importantly, PI3Kd deficiency severely impaired numbers, proliferation, immunosuppressive functions, and stability of regulatory CD4+ T cells (Tregs). Consequently, adoptive transfer of PI3Kd+/+ Tregs fully restrained the atherosclerotic plaque burden in PI3Kd-/- transplanted Ldlr-/- mice without affecting B-cell numbers and serum immunoglobulins, whereas transferred PI3Kd-/- Tregs failed to relieve atherosclerosis progression. Conclusions Here, we demonstrate that PI3Kd plays a crucial role in Tregs, Th1 cells, and B cells during atherogenesis. Lack of PI3Kd signalling specifically in atheroprotective Treg responses outplays its impact on B-cell and proatherogenic Th1 responses, thus leading to aggravated atherosclerosis. Hence, PI3Kd is a key regulator of Treg biology and thereby protects against atherosclerosis, suggesting that fine-tuning PI3Kd signalling may represent a promising target for Treg-directed therapy.

Autoimmune and Neoplastic Outcomes After the mRNA Vaccination: The Role of T Regulatory Cell Responses

A plethora of autoimmune disease incidences occured after COVID-19 mRNA injections were rolled out. Aggressive cancer cases have occurred in the bodies of recipients at sites where the mRNA was injected and at distant metastatic sites. The mRNA vaccines cause thymic involution (shrinking) and dysregulation of the T regulatory (Treg) and T effector (Teff) homeostatic cell balance. Activated immune cells deliver spike protein to the thymic epithelial cells, damaging them. The Treg/Teff balance may determine the fate of autoimmunity and/or cancer and is different for patients with cancer versus those without any cancerous tissues. Repeated mRNA injections lead to empirical evidence of impaired immune functions (elevated IgG4, PD-L1), associated with increased autoimmunity and cancer risks, and decreased resistance to infections. In the with-cancer recipients, the mRNA vaccine may be associated with either autoimmunity or further progression of the cancer(s) depending on the immunotherapy treatment the patient receives. When an antigen stimulates the immune system, specific T regulatory (Treg) and T effector (Teff) subpopulations develop from naïve T cells. An imbalance between Treg and Teff cells can lead to either cancer or autoimmunity. Treg cells are beneficial in that they protect from autoimmunity. However, they suppress the immune response to tumors. In this review, we analyze Treg responses after SARS-CoV-2 mRNA vaccination and find distinct pathological responses under differing conditions. Injection with modified mRNA can lead to a delayed but highly active immune response, resulting in overactivation of the inflammasome. The mRNA “vaccine” induces a very strong IgG antibody response, while suppressing CD8+ T cell activation. Exosomes distribute the recombinant, synthetic spike protein and the mRNA encoding it throughout the organism. In cancer patients, disease progression depends on the starting point of the cancer patient at the time of injection and the type of cancer treatment underway. Migration of circulating dendritic cells and Treg cells back to the thymus, while they are carrying spike protein, damages the medullary thymic epithelial cells and accelerates thymic involution, a direct cause of inflammaging and immunosenescence. In summary, the Treg responses to mRNA injections and subsequent mRNA-encoded SARS-CoV-2 spike protein expression may disrupt immune capacities resulting in accelerated development of autoimmune disease and cancer. The processes discussed here are consistent with both epidemiological findings and case reports.

The divergent outcome of IL-4Rα signalling on Foxp3 T regulatory cells in listeriosis and tuberculosis.

Forkhead box P3 (Foxp3) T regulatory cells are critical for maintaining self-tolerance, immune homeostasis, and regulating the immune system. We investigated interleukin-4 receptor alpha (IL-4Rα) signalling on T regulatory cells (Tregs) during Listeria monocytogenes (L. monocytogenes) infection using a mouse model on a BALB/c background, specifically with IL-4Rα knockdown in Tregs (Foxp3creIL-4Rα-/lox). We showed an impairment of Treg responses, along with a decreased bacterial burden and diminished tissue pathology in the liver and spleen, which translated into better survival. Mechanistically, we observed an enhancement of the Th1 signature, characterised by increased expression of the T-bet transcription factor and a greater number of effector T cells producing IFN-γ, IL-2 following ex-vivo stimulation with heat-killed L. monocytogenes in Foxp3creIL-4Rα-/lox mice. Furthermore, CD8 T cells from Foxp3creIL-4Rα-/lox mice displayed increased cytotoxicity (Granzyme-B) with higher proliferation capacity (Ki-67), better survival (Bcl-2) with concomitant reduced apoptosis (activated caspase 3). In contrast to L. monocytogenes, Foxp3creIL-4Rα-/lox mice displayed similar bacterial burdens, lung pathology and survival during Mycobacterium tuberculosis (M. tuberculosis) infection, despite increased T cell numbers and IFN-γ, TNF and IL-17 production. Our results demonstrated that the diminished IL-4Rα signalling on Foxp3+ T regulatory cells resulted in a loss of their functionality, leading to survival benefits in listeriosis but not in tuberculosis.

Hematopoietic PI3Kδ deficiency aggravates murine atherosclerosis through impairment of regulatory T cells.

Chronic activation of the adaptive immune system is a hallmark of atherosclerosis. As PI3Kδ is a key regulator of T and B-cell differentiation and function, we hypothesized that alleviation of adaptive immunity by PI3Kδ inactivation may represent an attractive strategy counteracting atherogenesis. As expected, lack of hematopoietic PI3Kδ in atherosclerosis-prone Ldlr-/- mice resulted in hindered T- and B-cell numbers, CD4+ effector T cells, Th1 response, and immunoglobulin levels. However, despite markedly impaired peripheral proinflammatory Th1 cells and atheromatous CD4+ T cells, the unexpected net effect of hematopoietic PI3Kδ deficiency was aggravated vascular inflammation and atherosclerosis. Further analyses revealed that PI3Kδ deficiency impaired numbers, immunosuppressive functions, and stability of regulatory CD4+ T cells (Tregs), whereas macrophage biology remained largely unaffected. Adoptive transfer of wild-type Tregs fully restrained the atherosclerotic plaque burden in Ldlr-/- mice lacking hematopoietic PI3Kδ, whereas PI3Kδ deficient Tregs failed to mitigate disease. Numbers of atheroprotective B-1 and proatherogenic B-2 cells as well serum immunoglobulin levels remained unaffected by adoptively transferred wild-type Tregs. In conclusion, we demonstrate that hematopoietic PI3Kδ ablation promotes atherosclerosis. Mechanistically, we identified PI3Kδ signaling as a powerful driver of atheroprotective Treg responses, which outweigh PI3Kδ driven proatherogenic effects of adaptive immune cells like Th1 cells.

Abstract B047: Antigenic properties determine the outcome of B cell driven anti-tumor immunity

Abstract B cells have the capacity to elicit both anti- and pro-tumorigenic effects; yet the determinants of productive B cell responses in cancer remain elusive. Using a system where a B cell neoantigen is either soluble or tethered to the surface of pancreatic cancer cells, we demonstrate that membrane-tethered antigen is sufficient to elicit activation of anti-tumor immunity and reduce tumor growth in an NK cell-dependent manner. We also show that decreased antigen affinity to the BCR promotes regulatory B cell function which can be overcome by increased avidity of membrane-tethered antigen. Furthermore, soluble and membrane-tethered antigens drive qualitatively distinct germinal center, plasma cell, memory B cell, and Treg responses. Finally, we describe two classes of membrane-associated antigens that correlate with GC B cell signature and improved survival in pancreatic cancer patients. Thus, antigen localization impacts basic mechanisms governing B cell differentiation and the resulting immune response to solid malignancy with implications for vaccine engineering. Citation Format: Colleen Sturdevant, Nancy Kren, Harrison Silva, Ismael Gomez, Austin Hepperla, Yuliya Pylayeva-Gupta. Antigenic properties determine the outcome of B cell driven anti-tumor immunity [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B047.

Acute Chikungunya Virus Infection Triggers a Diverse Range of T Helper Lymphocyte Profiles.

Chikungunya virus (CHIKV) is an arbovirus causing acute febrile illness with severe joint pain, often leading to chronic arthralgia. This study investigated the adaptive immune responses during the early stages of symptomatic acute CHIKV infection, focusing on the transcription factors and cytokines linked to Th1, Th2, Th17, and Treg cells. Thirty-six individuals were enrolled: nine healthy controls and 27 CHIKV-positive patients confirmed by qRT-PCR. Blood samples were analyzed for the mRNA expression of transcription factors (Tbet, GATA3, FoxP3, STAT3, RORγt) and cytokines (IFN-γ, IL-4, IL-17, IL-22, TGF-β, IL-10). The results showed the significant upregulation of Tbet, GATA3, FoxP3, STAT3, and RORγt in CHIKV-positive patients, with RORγt displaying the highest increase. Correspondingly, cytokines IFN-γ, IL-4, IL-17, and IL-22 were upregulated, while TGF-β was downregulated. Principal component analysis (PCA) confirmed the distinct immune profiles between CHIKV-positive and healthy individuals. A correlation analysis indicated that higher Tbet expression correlated with a lower viral load, whereas FoxP3 and TGF-β were associated with higher viral loads. Our study sheds light on the intricate immune responses during acute CHIKV infection, characterized by a mixed Th1, Th2, Th17, and Treg response profile. These results emphasize the complex interplay between different adaptive immune responses and how they may contribute to the pathogenesis of Chikungunya fever.

T-cell responses in colorectal peritoneal metastases are recapitulated in a humanized immune system mouse model.

The occurrence of peritoneal metastasis (PM) in patients with colorectal cancer (CRC) has a dismal prognosis. There is often limited response to systemic- and immunotherapy, even in microsatellite unstable (MSI) CRC. To overcome therapy resistance, it is critical to understand local immune environment in the peritoneal cavity, and to develop models to study anti-tumor immune responses. Here, we defined the peritoneal immune system (PerIS) in PM-CRC patients and evaluate the pre-clinical potential of a humanized immune system (HIS) mouse model for PM-CRC. We studied the human PerIS in PM-CRC patients (n=20; MSS 19/20; 95%) and in healthy controls (n=3). HIS mice (NODscid gamma background; n=18) were generated, followed by intraperitoneal injection of either saline (HIS control; n=3) or human MSS/MSI CRC cell lines HUTU80, MDST8 and HCT116 (HIS-PM, n=15). Immune cells in peritoneal fluid and peritoneal tumors were analyzed using cytometry by time of flight (CyTOF). The human and HIS mouse homeostatic PerIS was equally populated by NK cells and CD4+- and CD8+ T cells, however differences were observed in macrophage and B cell abundance. In HIS mice, successful peritoneal engraftment of both MSI and MSS tumors was observed (15/15; 100%). Both in human PM-CRC and in the HIS mouse PM-CRC model, we observed that MSS PM-CRC triggered a CD4+ Treg response in the PerIS, while MSI PM-CRC drives CD8+ TEMs responses. In conclusion, T cell responses in PM-CRC in HIS mice mirror those in human PM-CRC, making this model suitable to study antitumor T cell responses in PM-CRC.

Trichinella spiralis Paramyosin Alleviates Collagen-Induced Arthritis in Mice by Modulating CD4+ T Cell Differentiation.

Rheumatoid arthritis (RA) is an autoimmune disease that significantly impacts quality of life by disrupting CD4+ T cell immune homeostasis. The identification of a low-side-effect drug for RA treatment is urgently needed. Our previous study suggests that Trichinella spiralis paramyosin (Ts-Pmy) has immunomodulatory effects, but its potential effect on CD4+ T cell response in RA remains unclear. In this study, we used a murine model to investigate the role of rTs-Pmy in regulating CD4+ T cell differentiation in collagen-induced arthritis (CIA). Additionally, we assessed the impact of rTs-Pmy on CD4+ T cell differentiation towards the Th1 and Th17 phenotypes, which are associated with inflammatory responses in arthritis, using in vitro assays. The results demonstrated that rTs-Pmy administration reduced arthritis severity by inhibiting Th1 and Th17 response while enhancing Treg response. Prophylactic administration of Ts-Pmy showed superior efficacy on CIA compared to therapeutic administration. Furthermore, in vitro assays demonstrated that rTs-Pmy could inhibit the differentiation of CD4+ T cells into Th1 and Th17 while inducing the production of Tregs, suggesting a potential mechanism underlying its therapeutic effects. This study suggests that Ts-Pmy may ameliorate CIA by restoring the immune balance of CD4+ T cells and provides new insights into the mechanism through which helminth-derived proteins exert their effects on autoimmune diseases.

The systemic cellular immune response against allogeneic mesenchymal stem cells is influenced by inflammation, differentiation and MHC compatibility: in vivo study in the horse.

The effectiveness and safety of allogeneic mesenchymal stem/stromal cells (MSCs) can be affected by patient's immune recognition. Thus, MSC immunogenicity and their immunomodulatory properties are crucial aspects for therapy. Immune responses after allogeneic MSC administration have been reported in different species, including equine. Interactions of allogenic MSCs with the recipient's immune system can be influenced by factors like matching or mismatching for the major histocompatibility complex (MHC) between donor-recipient, and by the levels of MHC expression in MSCs. The latter can vary upon MSC inflammatory exposure or differentiation, such as chondrogenic induction, making both priming and differentiation interesting therapeutic strategies. This study investigated the systemic in vivo immune cellular response against allogeneic equine MSCs in these situations. Either MSCs in basal conditions (MSC-naïve), pro-inflammatory primed (MSC-primed) or chondrogenically differentiated (MSC-chondro) were repeatedly administered subcutaneously into autologous, MHC-matched or MHC-mismatched allogeneic equine recipients. At different time-points after each administration, lymphocytes were obtained from recipient horses and exposed in vitro to the same type of MSCs to assess the proliferative response of different T cell subsets (cytotoxic, helper, regulatory), B cells, and interferon gamma (IFNγ) secretion. Higher proliferative response of helper and cytotoxic T lymphocytes and IFNγ secretion was observed in response to all types of MHC-mismatched MSCs over MHC-matched ones. MSC-primed produced the highest immune response, followed by MSC-naïve, and MSC-chondro. However, MSC-primed activated Treg and had a mild effect on B cells, and the response after their second administration was similar to the first one. On the other hand, both MSC-chondro and MSC-naïve barely induced Treg response but promoted B lymphocyte activation, and proportionally induced a higher cell response after the second administration. In conclusion, both the type of MSC conditioning and the MHC compatibility influenced systemic immune recognition of equine MSCs after single and repeated administrations, but the response was different. Selecting MHC-matched donors would be particularly recommended for MSC-primed and repeated MSC-naïve administrations. While MHC-mismatching in MSC-chondro would be less critical, B cell response should not be ignored. Comprehensively investigating the in vivo immune response against equine allogeneic MSCs is crucial for advancing veterinary cell therapies.

Flagellin conjugated Per a 10 and its T cell peptides attenuate airway inflammation and restore cellular function.

Adjuvants were used to modulate response towards relevant immune cells. The present study aims to investigate FlaA-conjugated Per a 10 and T cell peptides in amelioration of allergic airway disease in mice. Mice given Per a 10 showed allergic features with higher cellular infiltration, IgE, Th-2 cytokines and alarmins. Fusion protein treatment reduced lung inflammation (p < 0.0001) and cellular infiltrates (p < 0.001) with higher IgG2a/IgE indicating resolution of disease. Immunotherapy with FPT1 and FPT3 reduces IL-4, IL-5 and IL-13 levels (p < 0.0001) with a fourfold increase in IFN-γ secretion in BALF. FPT1- and FPT3-treated mice have increased IL-10 and TGF-β levels (p < 0.001) with CD4+Foxp3+ T cells (p < 0.01) indicating Treg response. There was enhanced expression of claudin-1 (1.7-fold) and occludin (fourfold) in lungs of FPT1- and FPT3-treated mice with reduced TSLP (p < 0.01) and IL-33 (p < 0.0001) secretion in BALF indicating recovery of epithelial function. Peptide-conjugated FlaA proteins showed protective immunity in mice and have potential for immunotherapy with restoration of cellular function.

The sterol element binding protein 1c (SREBP1c) preserves cellular metabolism and immunosuppressive function of regulatory t cells

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Cariplo Foundation PRIN (Italian Ministry of University and Research) Aim Balance of cellular metabolism is increasingly recognized as a hallmark of physiologic cellular functions; this also extends to cells of the immune system. Here, we aimed at investigating the role of SREBP1c, a key protein regulating intracellular fatty acid (FA) metabolism, on the metabolism and function of Treg, that play a key role in immune tolerance maintenance. Material and Methods A detailed immunophenotyping through flow cytometry and metabolic profiling (metabolomics and seahorse analysis) of isolated Tregulatory (CD4+CD25+, nTreg) and in vitro induced Treg (iTreg) cells were performed together with in vitro and in vivo assays of Treg function from SREBP1c KO and WT littermates. RNAseq and lipidomics was performed on iTreg. Results Srebp1c deficiency reduced suppressive (-21%,p&amp;lt;0,01) and increased migratory function (+40%,p&amp;lt;0,05) of nTreg and iTreg, tested by in vitro assays. In vivo, Srebp1c KO mice presented reduced circulating and tissues’ level of Treg compared to WT mice (-66%,p&amp;lt;0,01) and nTreg from Srebp1c KO mice worsened Experimental Autoimmune Encephalomyelitis progression compared to WT nTreg. We addressed impaired Treg function to metabolic alteration due to Srebp1c deficiency: KO iTreg showed an increased glycolytic potential with preserved mitochondrial function coupled to accumulation of glycolytic metabolites and lactate (+20%,p&amp;lt;0,01) and reduced energy charge (-40%,p&amp;lt;0.01). We associated the switch to anaerobic glycolysis in KO Treg to an impaired lipid metabolism, as suggested by impaired abundance of lipid species (TG, LPC and PC); this was confirmed by RNAseq showing a downregulation of lipid metabolism’s pathways and upregulation of glycolysis. In parallel, tolerogenic response was impaired, a phenotype associated to a reduced transcription and activation of Foxp3, the master regulator of Treg function. Conclusion By restrain glycolysis and preserving lipid metabolism, our data have identified SREBP1c as a checkpoint crucial for the immunometabolic suppressive response of Tregs.

Pharmacometabolomics applied to low-dose interleukin-2 treatment in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease. The immunosuppressive functions of regulatory T lymphocytes (Tregs) are impaired in ALS, and correlate to disease progression. The phase 2a IMODALS trial reported an increase in Treg number in ALS patients following the administration of low-dose (ld) interleukin-2 (IL-2). We propose a pharmacometabolomics approach to decipher metabolic modifications occurring in patients treated with ld-IL-2 and its relationship with Treg response. Blood metabolomic profiles were determined on days D1, D64, and D85 from patients receiving 2 MIU of IL-2 (n = 12) and patients receiving a placebo (n = 12). We discriminated the three time points for the treatment group (average error rate of 42%). Among the important metabolites, kynurenine increased between D1 and D64, followed by a reduction at D85. The percentage increase of Treg number from D1 to D64, as predicted by the metabolome at D1, was highly correlated with the observed value. This study provided a proof of concept for metabolic characterization of the effect of ld-IL-2 in ALS. These data could present advances toward a personalized medicine approach and present pharmacometabolomics as a key tool to complement genomic and transcriptional data for drug characterization, leading to systems pharmacology.

Immunomodulation of adipose-derived mesenchymal stem cells on peripheral blood mononuclear cells in colorectal cancer patients with COVID-19.

Accumulating evidence has shown that adipose tissue-derived mesenchymal stem cells (ADSCs) are an effective therapeutic approach for managing coronavirus disease 2019 (COVID-19); however, further elucidation is required to determine their underlying immunomodulatory effect on the mRNA expression of T helper cell-related transcription factors (TFs) and cytokine release in peripheral blood mononuclear cells (PBMCs). To investigate the impact of ADSCs on the mRNA expression of TFs and cytokine release in PBMCs from colorectal cancer (CRC) patients with severe COVID-19 (CRC+ patients). PBMCs from CRC+ patients (PBMCs-C+) and age-matched CRC patients (PBMCs-C) were stimulated and cultured in the presence/absence of ADSCs. The mRNA levels of T-box TF TBX21 (T-bet), GATA binding protein 3 (GATA-3), RAR-related orphan receptor C (RORC), and forkhead box P3 (FoxP3) in the PBMCs were determined by reverse transcriptase-polymerase chain reaction. Culture supernatants were evaluated for levels of interferon gamma (IFN-γ), interleukin 4 (IL-4), IL-17A, and transforming growth factor beta 1 (TGF-β1) using an enzyme-linked immunosorbent assay. Compared with PBMCs-C, PBMCs-C+ exhibited higher mRNA levels of T-bet and RORC, and increased levels of IFN-γ and IL-17A. Additionally, a significant decrease in FoxP3 mRNA and TGF-β1, as well as an increase in T-bet/GATA-3, RORC/FoxP3, IFN-γ/IL-4, and IL-17A/TGF-β1 ratios were observed in PBMCs-C+. Furthermore, ADSCs significantly induced a functional regulatory T cell (Treg) subset, as evidenced by an increase in FoxP3 mRNA and TGF-β1 release levels. This was accompanied by a significant decrease in the mRNA levels of T-bet and RORC, release of IFN-γ and IL-17A, and T-bet/GATA-3, RORC/FoxP3, IFN-γ/IL-4, and IL-17A/TGF-β1 ratios, compared with the PBMCs-C+alone. The present in vitro studies showed that ADSCs contributed to the immunosuppressive effects on PBMCs-C+, favoring Treg responses. Thus, ADSC-based cell therapy could be a beneficial approach for patients with severe COVID-19 who fail to respond to conventional therapies.

Complement receptor 3-dependent engagement by Candida glabrata β-glucan modulates dendritic cells to induce regulatory T-cell expansion.

Candida glabrata is an important pathogen causing invasive infection associated with a high mortality rate. One mechanism that causes the failure of Candida eradication is an increase in regulatory T cells (Treg), which play a major role in immune suppression and promoting Candida pathogenicity. To date, how C. glabrata induces a Treg response remains unclear. Dendritic cells (DCs) recognition of fungi provides the fundamental signal determining the fate of the T-cell response. This study investigated the interplay between C. glabrata and DCs and its effect on Treg induction. We found that C. glabrata β-glucan was a major component that interacted with DCs and consequently mediated the Treg response. Blocking the binding of C. glabrata β-glucan to dectin-1 and complement receptor 3 (CR3) showed that CR3 activation in DCs was crucial for the induction of Treg. Furthermore, a ligand-receptor binding assay showed the preferential binding of C. glabrata β-glucan to CR3. Our data suggest that C. glabrata β-glucan potentially mediates the Treg response, probably through CR3-dependent activation in DCs. This study contributes new insights into immune modulation by C. glabrata that may lead to a better design of novel immunotherapeutic strategies for invasive C. glabrata infection.

The Role of Extracellular Vesicles in Allergic Sensitization: A Systematic Review.

Allergies affect approximately 10-30% of people worldwide, with an increasing number of cases each year; however, the underlying mechanisms are still poorly understood. In recent years, extracellular vesicles (EVs) have been suggested to play a role in allergic sensitization and skew to a T helper type 2 (Th2) response. The aim of this review is to highlight the existing evidence of EV involvement in allergies. A total of 22 studies were reviewed; 12 studies showed EVs can influence a Th2 response, while 10 studies found EVs promoted a Th1 or Treg response. EVs can drive allergic sensitization through up-regulation of pro-Th2 cytokines, such as IL-4 and IL-13. In addition, EVs from MRSA can induce IgE hypersensitivity in mice towards MRSA. On the other hand, EVs can induce tolerance in the immune system; for example, pre-exposing OVA-loaded EVs prevented OVA sensitization in mice. The current literature thus suggests that EVs play an essential role in allergy. Further research utilizing human in vitro models and clinical studies is needed to give a reliable account of the role of EVs in allergy.

Immune regulation and therapeutic application of T regulatory cells in liver diseases.

CD4+ CD25+ FOXP3+ T regulatory cells (Tregs) are a subset of the immunomodulatory cell population that can inhibit both innate and adaptive immunity by various regulatory mechanisms. In hepatic microenvironment, proliferation, plasticity, migration, and function of Tregs are interrelated to the remaining immune cells and their secreted cytokines and chemokines. In normal conditions, Tregs protect the liver from inflammatory and auto-immune responses, while disruption of this crosstalk between Tregs and other immune cells may result in the progression of chronic liver diseases and the development of hepatic malignancy. In this review, we analyze the deviance of this protective nature of Tregs in response to chronic inflammation and its involvement in inducing liver fibrosis, cirrhosis, and hepatocellular carcinoma. We will also provide a detailed emphasis on the relevance of Tregs as an effective immunotherapeutic option for autoimmune diseases, liver transplantation, and chronic liver diseases including liver cancer.

Cytokine and T cell responses in post-chikungunya viral arthritis: A cross-sectional study.

To define the relationship between chronic chikungunya post-viral arthritis disease severity, cytokine response and T cell subsets in order to identify potential targets for therapy. Participants with chikungunya arthritis were recruited from Colombia from 2019-2021. Arthritis disease severity was quantified using the Disease Activity Score-28 and an Arthritis-Flare Questionnaire adapted for chikungunya arthritis. Plasma cytokine concentrations (interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, interferon-γ and tumor necrosis factor (TNF)) were measured using a Meso Scale Diagnostics assay. Peripheral blood T cell subsets were measured using flow cytometry. Among participants with chikungunya arthritis (N = 158), IL-2 levels and frequency of regulatory T cells (Tregs) were low. Increased arthritis disease activity was associated with higher levels of inflammatory cytokines (IL-6, TNF and CRP) and immunoregulatory cytokine IL-10 (p<0.05). Increased arthritis flare activity was associated with higher Treg frequencies (p<0.05) without affecting T effector (Teff) frequencies, Treg/Teff ratios and Treg subsets. Finally, elevated levels of IL-2 were correlated with increased Treg frequency, percent Tregs out of CD4+ T cells, and Treg subsets expressing immunosuppressive markers, while also correlating with an increased percent Teff out of live lymphocytes (p<0.05). Chikungunya arthritis is characterized by increased inflammatory cytokines and deficient IL-2 and Treg responses. Greater levels of IL-2 were associated with improved Treg numbers and immunosuppressive markers. Future research may consider targeting these pathways for therapy.

IFNγ insufficiency during mouse intra-vaginal Chlamydia trachomatis infection exacerbates alternative activation in macrophages with compromised CD40 functions

Chlamydia trachomatis (C.tr), an obligate intracellular pathogen, causes asymptomatic genital infections in women and is a leading cause of preventable blindness. We have developed in vivo mouse models of acute and chronic C. trachomatis genital infection to explore the significance of macrophage-directed response in mediating immune activation/suppression. Our findings reveal that during chronic and repeated C. trachomatis infections, Th1 response is abated while Treg response is enhanced. Additionally, an increase in exhaustion (PD1, CTLA4) and anergic (Klrg3, Tim3) T cell markers is observed during chronic infection. We have also observed that M2 macrophages with low CD40 expression promote Th2 and Treg differentiation leading to sustained C. trachomatis genital infection. Macrophages infected with C. trachomatis or treated with supernatant of infected epithelial cells drive them to an M2 phenotype. C. trachomatis infection prevents the increase in CD40 expression as observed in western blots and flow cytometric analysis. Insufficient IFNγ, as observed during chronic infection, leads to incomplete clearance of bacteria and poor immune activation. C. trachomatis decapacitates IFNγ responsiveness in macrophages via hampering IFNγRI and IFNγRII expression which can be correlated with poor expression of MHC-II, CD40, iNOS and NO release even following IFNγ supplementation. M2 macrophages during C. trachomatis infection express low CD40 rendering immunosuppressive, Th2 and Treg differentiation which could not be reverted even by IFNγ supplementation. The alternative macrophages also harbour high bacterial load and are poor responders to IFNγ, thus promoting immunosuppression. In summary, C. trachomatis modulates the innate immune cells, attenuating the anti-chlamydial functions of T cells in a manner that involves decreased CD40 expression on macrophages.

Assessing the effectiveness of Interleukin-2 therapy in experimental type 1 diabetes

AimMuch focus of immunotherapy for type 1 diabetes (T1D) has been devoted on selectively boosting regulatory T (Treg) cells using low dose IL-2 due to their constitutive expression of IL-2Rα, CD25. However, several clinical trials using a low dose of IL-2 only showed a limited improvement of metabolic control. It can therefore be hypothesized that further decreasing IL-2 dosage may increase the selective responsiveness of Treg cells.MethodsWe induced experimental T1D using multiple low dose streptozotocin (STZ) injections and treated the mice with an ultra-low dose IL-2 (uIL-2, approximately 7-fold lower than low dose). Immune response was studied using multicolor flow cytometry.ResultsWe found that uIL-2 did not protect STZ mice from developing hyperglycemia. It did neither increase Treg cell proportions, nor did it correct the phenotypic shift of Treg cells seen in T1D. It only partially decreased the proportion of IFN-γ+ T cells. Likewise, uIL-2 also did not protect the dysfunction of regulatory B (Breg) cells. Strikingly, when administered in combination with an anti-inflammatory cytokine IL-35, uIL-2 abrogated IL-35’s protective effect. Low dose IL-2, on the other hand, protected half of the STZ mice from developing hyperglycemia. No difference was found in the Treg and Breg response, and it only tended to decrease CD80 expression in macrophages and dendritic cells.ConclusionIn conclusion, further decreasing IL-2 dosage may not be a suitable approach for T1D therapy, and the limited success suggests that an alternative low dose IL-2 therapy strategy or other immunotherapies should be considered.