Directed differentiation of regulatory T cells from naive T cells and prevention of their inflammation-mediated instability using small molecules

COVID-19 immunopathology with emphasis on Th17 response and cell-based immunomodulation therapy: Potential targets and challenges

The role of the immune system against coronavirus disease 2019 (COVID-19) is unknown in many aspects, and the protective or pathologic mechanisms of the immune response are poorly understood. Pro-inflammatory cytokine release and a consequent cytokine storm can lead to acute respiratory distress syndrome (ARDS) and result in multi-organ failure. There are many T cell subsets during anti-viral immunity. The Th17-associated response, as a pro-inflammatory pathway, and its consequent outcomes in many autoimmune disorders play a fundamental role in progression of systemic hyper-inflammation during COVID-19. Therapeutic strategies based on immunomodulation therapy could be helpful for targeting hyper-inflammatory immune responses in COVID-19, especially Th17-related inflammation and hyper-cytokinemia. Cell-based immunotherapeutic approaches including mesenchymal stem cells (MSCs), tolerogenic dendritic cells (tolDCs) and regulatory T cells (Tregs) seem to be promising strategies as orchestrators of the immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this review, we highlight Th17-related immunopathology of SARS-CoV-2 infection and discuss cell-based immunomodulatory strategies and their mechanisms for regulation of the hyper-inflammation during COVID-19.

Clinical and diagnostic potential of regulatory T cell markers: From bench to bedside

Regulatory T (Treg) cells are heterogeneous immune cell populations residing in the thymus and peripheral lymphatic tissues. This immune cell plays a central and critical role in maintaining immune tolerance against undesirable immune responses. Treg cells' phenotypic heterogeneity caused by different pathological conditions makes their identification and differentiation from non-suppressive T cells difficult. On the other hand, using nonspecific markers and variable isolation panels leads to undesirable outcomes. There are a variety of markers to identify functional Treg cells, including CD25, FOXP3, and CTLA-4, as well as the epigenetic signature of forkhead box P3 (FOXP3), which can be used for both natural and induced Treg cells. Phenotypic heterogeneity is a major concern in Treg purification when using nonspecific markers, which can be addressed by utilizing suitable isolation panels designed for different purposes. This review presents a clinical framework for Treg detection and isolation, focusing on Treg markers such as CD25, FOXP3, CTLA-4, CD127, GPA-33, and TSDR demethylation to design Treg isolation panels suitable for different Treg therapy purposes. The current review also highlights new reliable Treg markers applicable for different purposes.

Th17/Treg cells regulated by interleukin 6 in the pathogenesis of chronic rhinosinusitis with nasal polyps

PURPOSE

To be investigated whether Th17/Treg cells regulated by Interleukin-6 in the pathogenesis of chronic rhinosinusitis with nasal polyps.

METHODS

The distributions of Th17 and Treg cells in peripheral blood mononuclear cells (PBMCs) and tissues got from 46 CRSwNP patients and 14 controls were evaluated. Th17 and Treg cells and cells-related cytokines in serum were assessed in means of cytometric bead array (CBA) multiplex assays and enzyme-linked immunosorbent assays (ELISAs). Spleen cells were isolated from spleen of 20 normal BALB/c mice (male), isolated and purified with CD4 antibody immunomagnetic bead kit. CD4+ cells were divided into three groups, including TGF-β1, TGF-β1+ IL-6 and control (PBS). Treg and Th17 cells and cells related cytokines were detected by flow cytometry (FCM) after collecting spleen cells. The level of IL-10 and IL-17 in supernatant was measured by ELISA.

RESULTS

Th17/Treg ratio and the level of IL-6 in both ECRSwNP (P < 0.05) and non-ECRSwNP (P < 0.05) were significantly increased when compared with control group, these were consistent with the previous findings. Experiments in vitro suggested that the level of Th17 cells in IL-6+ TGF-β1 group was significantly increased than TGF-β1 group and control group (P < 0.05). The ratio of cells expressed RoRγt in IL-6+ TGF-β1 group was much higher than TGF-β1 group (P < 0.05).

CONCLUSION

IL-6 might regulate the function of Th17 and Treg cells and the Th17/Treg ratio and have a role in the pathogenesis of CRSwNP.

Contribution of Regulatory T Cell Methylation Modifications to the Pathogenesis of Allergic Airway Diseases

Regulatory T (Treg) cells are a subtype of CD4⁺ T cells that play a significant role in the protection from autoimmunity and the maintenance of immune tolerance via immune regulation. Epigenetic modifications of Treg cells (i.e., cytosine methylation at the promoter region of the transcription factor, Forkhead Box P3) have been found to be closely associated with allergic diseases, including allergic rhinitis, asthma, and food allergies. In this study, we highlighted the recent evidence on the contribution of epigenetic modifications in Treg cells to the pathogenesis of allergic diseases. Moreover, we also discussed directions for future clinical treatment approaches, with a particular emphasis on Treg cell-targeted therapies for allergic disorders.

Induction of stable human FOXP3+ Tregs by a parasite-derived TGF-β mimic

Immune homeostasis in the intestine is tightly controlled by FOXP3⁺ regulatory T cells (Tregs), defects of which are linked to the development of chronic conditions, such as inflammatory bowel disease (IBD). As a mechanism of immune evasion, several species of intestinal parasites boost Treg activity. The parasite Heligmosomoides polygyrus is known to secrete a molecule (Hp-TGM) that mimics the ability of TGF-β to induce FOXP3 expression in CD4⁺ T cells. The study aimed to investigate whether Hp-TGM could induce human FOXP3⁺ Tregs as a potential therapeutic approach for inflammatory diseases. CD4⁺ T cells from healthy volunteers were expanded in the presence of Hp-TGM or TGF-β. Treg induction was measured by flow cytometric detection of FOXP3 and other Treg markers, such as CD25 and CTLA-4. Epigenetic changes were detected using ChIP-Seq and pyrosequencing of FOXP3. Treg phenotype stability was assessed following inflammatory cytokine challenge and Treg function was evaluated by cellular co-culture suppression assays and cytometric bead arrays for secreted cytokines. Hp-TGM efficiently induced FOXP3 expression (> 60%), in addition to CD25 and CTLA-4, and caused epigenetic modification of the FOXP3 locus to a greater extent than TGF-β. Hp-TGM-induced Tregs had superior suppressive function compared with TGF-β-induced Tregs, and retained their phenotype following exposure to inflammatory cytokines. Furthermore, Hp-TGM induced a Treg-like phenotype in in vivo differentiated Th1 and Th17 cells, indicating its potential to re-program memory cells to enhance immune tolerance. These data indicate Hp-TGM has potential to be used to generate stable human FOXP3⁺ Tregs to treat IBD and other inflammatory diseases.