TIGIT-Fc Prolongs Corneal Allograft Survival in Mice by Upregulating TIGIT/CD226 Expression and the Proportion of Helios + Foxp3 + Treg Cells

Rho-kinase inhibitor alleviates CD4+T cell mediated corneal graft rejection by modulating its STAT3 and STAT5 activation

Penetrating keratoplasty remains the most common treatment to restore vision for corneal diseases. Immune rejection after corneal transplantation is one of the major causes of graft failure. In recent years, Rho-associated protein kinase (ROCK) inhibitors have been found to be associated with the activation of the STATs pathway and are widely studied in autoimmune diseases. Therefore, it may be possible that the ROCK inhibitors also participate in the local and systemic immune regulation in corneal transplantation through activation of the STATs pathway and affect the CD4+ T cell differentiation. This study aimed to explore the role of ROCK-STATs pathway in the occurrence of immune rejection in corneal transplantation by applying Y27632, a ROCK inhibitor, to the recipient mice and peripheral CD4+ T cells. We found that Y27632 significantly up-regulated the phosphorylation level of STAT5 in both spleen and lymph nodes, down-regulated the phosphorylation level of STAT3 in the CD4+ T cells in the spleen. It also increased the proportion of CD4+CD25+Foxp3+Helios+ Tregs while decreased CD4+IL17A+ -Th17 cells. Moreover, Y27632 also reduced the proportion of dendritic cells in both spleen and lymph nodes, as well as the expression level of CD86 on their surfaces in the spleen, while the proportion of macrophages was not affected. The expression levels of ROCK1, ROCK2, CD11c and IL-17A mRNA were also found to be low in the graft tissue while the expression of Helios was upregulated. Rho-kinase inhibitor can modulate the balance of Tregs/Th17 by regulating the phosphorylation levels of both STAT3 and STAT5, thereby inhibiting the occurrence of immune rejection in allogeneic corneal transplantation.

Beyond FOXP3: a 20-year journey unravelling human regulatory T-cell heterogeneity

The initial idea of a distinct group of T-cells responsible for suppressing immune responses was first postulated half a century ago. However, it is only in the last three decades that we have identified what we now term regulatory T-cells (Tregs), and subsequently elucidated and crystallized our understanding of them. Human Tregs have emerged as essential to immune tolerance and the prevention of autoimmune diseases and are typically contemporaneously characterized by their CD3+CD4+CD25high CD127lowFOXP3+ phenotype. It is important to note that FOXP3+ Tregs exhibit substantial diversity in their origin, phenotypic characteristics, and function. Identifying reliable markers is crucial to the accurate identification, quantification, and assessment of Tregs in health and disease, as well as the enrichment and expansion of viable cells for adoptive cell therapy. In our comprehensive review, we address the contributions of various markers identified in the last two decades since the master transcriptional factor FOXP3 was identified in establishing and enriching purity, lineage stability, tissue homing and suppressive proficiency in CD4+ Tregs. Additionally, our review delves into recent breakthroughs in innovative Treg-based therapies, underscoring the significance of distinct markers in their therapeutic utilization. Understanding Treg subsets holds the key to effectively harnessing human Tregs for immunotherapeutic approaches.

IL-35 Stabilizes Treg Phenotype to Protect Cardiac Allografts in Mice

BACKGROUND

Interleukin-35 (IL-35), secreted by regulatory T cells (Treg) and B cells, is immunosuppressive under both physiological and pathological conditions. However, the role of IL-35 in all responses has yet to be investigated. Here, we demonstrate that IL-35 protects allografts by stabilizing the Treg phenotype and suppressing CD8 + T-cell activation in a mouse heart transplantation model.

METHODS

The effect of IL-35 on immune cell infiltration in grafts and secondary lymphoid organs was examined using mass cytometry, flow cytometry, and immunofluorescence. Moreover, using quantitative real-time polymerase chain reaction, flow cytometry, and phospho-flow assays, we demonstrated that IL-35 maintains Treg phenotypes to restrain CD8 + T cells via the gp130/signal transducer and activator of transcription 1 pathway.

RESULTS

Mass cytometry analysis of intragraft immune cells showed that IL-35 decreased CD8 + T-cell infiltration and increased Foxp3 and IL-35 expressions in Treg. In vitro, we demonstrated that IL-35 directly promoted Treg phenotypic and functional stability and its IL-35 secretion, generating a positive feedback loop. However, Treg are required for IL-35 to exert its suppressive effect on CD8 + T cells in vitro. After depleting Treg in the recipient, IL-35 did not prolong graft survival or decrease CD8 + T-cell infiltration. Mechanistically, we found that IL-35 sustained Treg stability via the gp130/signal transducer and activator of transcription 1 signaling pathway.

CONCLUSIONS

Our findings highlight that IL-35 stabilizes the Treg phenotype to ameliorate CD8 + T-cell infiltration in the allograft, which has never been described in the transplanted immunological milieu.

The frequency of peripheral PD-1+ TCD4+ cells is reversely associated with serum creatinine levels in recipients of kidney allografts

The long-term survival of solid organ allografts remains a challenge for organ transplantation systems worldwide. T-cell exhaustion has been supposed to be associated with immunologic tolerance in transplantation and might reflect the immunologic status in recipients. The aim of the present study was to compare the TCD4+ cells of kidney transplant recipients with high and low serum creatinine levels for their expressions of PD-1 and TIGIT as two well-known exhaustion markers. Blood samples were taken from 20 kidney allograft recipients with serum creatinine levels above 2 mg/dL and 20 recipients with creatinine levels below 2 mg/dL. The percentages of PD-1+ CD4+ and TIGIT+ CD4+ cells were analyzed along with the evaluation of TNF-α, IFN-γ, and IL-10 release from peripheral blood mononuclear cells (PBMCs). The patients with serum creatinine levels below 2 mg/dL demonstrated a higher frequency of PD-1+ CD4+ T-cells (p = 0.003) along with lower TNF-α secretion from PBMCs (p = 0.028). The frequency of PD-1 + CD4+ T-cells was reversely correlated with the serum creatinine levels in recipients of kidney allografts (r = 0.59, p < 0.001). Besides, the MFI of TIGIT on TCD4+ cells demonstrated a trend for higher expression in patients with serum creatinine levels below 2 mg/dL (p = 0.070). The expression of PD-1+ on CD4+ T-cells demonstrated a potential for estimation of the immunologic status of the host in interaction with alloantigens. The exhaustion markers could be regarded as potential diagnostic indicators for the evaluation of immunologic tolerance in renal transplantation.

Tregs in transplantation tolerance: role and therapeutic potential

CD4+ Foxp3+ regulatory T cells (Tregs) are indispensable for preventing autoimmunity, and they play a role in cancer and transplantation settings by restraining immune responses. In this review, we describe evidence for the importance of Tregs in the induction versus maintenance of transplantation tolerance, discussing insights into mechanisms of Treg control of the alloimmune response. Further, we address the therapeutic potential of Tregs as a clinical intervention after transplantation, highlighting engineered CAR-Tregs as well as expansion of donor and host Tregs.