Newly Found Peacekeeper: Potential of CD8+ Tregs for Graft-Versus-Host Disease

Low-dose interleukin 2 therapy halts the progression of post-streptococcal autoimmune complications in a rat model of rheumatic heart disease

Acute rheumatic fever (ARF) is an autoimmune disease triggered by antibodies and T cells targeting the group A Streptococcus (GAS, Strep A) bacterium, often leading to rheumatic heart disease (RHD) and Sydenham's chorea. Long-term monthly penicillin injections are recognized as a cornerstone of public health programs to prevent Strep A reinfection and progression of ARF. However, compliance is poor, and better tools are required to slow disease progression. Preclinical evidence suggests that this can be achieved. Using a rat model that replicates post-streptococcal autoimmune complications, we explored the potential of low-dose interleukin-2 (LD-IL-2) as an immunotherapeutic intervention for ARF/RHD. In this model, injections of recombinant M protein from Strep A type 5 (rM5) to Lewis rats induce cardiac tissue inflammation, conduction abnormalities, and cross-reactive antibodies against cardiac and brain proteins central to disease pathogenesis. In animals injected with rM5 and treated with LD-IL-2, no cardiac functional or histological changes was observed. LD-IL-2 therapy effectively reduced the production of cross-reactive antibodies raised against host proteins and significantly increased regulatory T cells in the mediastinal lymph nodes. These novel findings suggest that LD-IL-2 will be an effective immunotherapeutic agent for treating ARF and has the potential to replace the standard monthly penicillin injections.

IMPORTANCE

Post-streptococcal autoimmune syndromes, including acute rheumatic fever, rheumatic heart disease, and Sydenham's chorea, represent a significant yet often under-recognized health and economic burden. This is especially true in low-income countries and among Indigenous populations in high-income nations, where the disease burden is most severe. These conditions arise from an autoimmune response to group A Streptococcus infections, leading to long-term health complications, disability, and premature death. Despite their widespread impact, no vaccine is currently available to prevent reinfections, and no specific therapy exists to treat the resulting autoimmune process. This study uses a rat model of rheumatic heart disease to evaluate the potential of low-dose interleukin 2 therapy in improving clinical outcomes and reducing the incidence of autoimmune diseases triggered by streptococcal infections.

Bone marrow immune cells and drug resistance in acute myeloid leukemia

In recent years, the relationship between the immunosuppressive niche of the bone marrow and therapy resistance in acute myeloid leukemia (AML) has become a research focus. The abnormal number and function of immunosuppressive cells, including regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs), along with the dysfunction and exhaustion of immunological effector cells, including cytotoxic T lymphocytes (CTLs), dendritic cells (DCs) and natural killer cells (NKs), can induce immune escape of leukemia cells and are closely linked to therapy resistance in leukemia. This article reviews the research progress on the relationship between immune cells in the marrow microenvironment and chemoresistance in AML, aiming to provide new ideas for the immunotherapy of AML.

Low-dose IL-2 therapy in autoimmune diseases: An update review

Regulatory T (Treg) cells are essential for maintaining self-immune tolerance. Reduced numbers or functions of Treg cells have been involved in the pathogenesis of various autoimmune diseases and allograft rejection. Therefore, the approaches that increase the pool or suppressive function of Treg cells in vivo could be a general strategy to treat different autoimmune diseases and allograft rejection. Interleukin-2 (IL-2) is essential for the development, survival, maintenance, and function of Treg cells, constitutively expressing the high-affinity receptor of IL-2 and sensitive response to IL-2 in vivo. And low-dose IL-2 therapy in vivo could restore the imbalance between autoimmune response and self-tolerance toward self-tolerance via promoting Treg cell expansion and inhibiting follicular helper T (Tfh) and IL-17-producing helper T (Th17) cell differentiation. Currently, low-dose IL-2 treatment is receiving extensive attention in autoimmune disease and transplantation treatment. In this review, we summarize the biology of IL-2/IL-2 receptor, the mechanisms of low-dose IL-2 therapy in autoimmune diseases, the application in the progress of different autoimmune diseases, including Systemic Lupus Erythematosus (SLE), Type 1 Diabetes (T1D), Rheumatoid Arthritis (RA), Autoimmune Hepatitis (AIH), Alopecia Areata (AA), Immune Thrombocytopenia (ITP) and Chronic graft-versus-host-disease (GVHD). We also discuss the future directions to optimize low-dose IL-2 treatments.

Efficiency and Toxicity of Imatinib Mesylate Combined with Atorvastatin Calcium in the Treatment of Steroid-Refractory Chronic Graft-versus-Host Disease: A Single-Center, Prospective, Single-Arm, Open-Label Study

INTRODUCTION

Steroid-refractory cGVHD (SR-cGVHD) presents new great challenges for treatment. We have reported that imatinib monotherapy was effective to SR-cGVHD, but the CR rate was not satisfactory and the benefit was not showed specific to some target organs, previously. Imatinib and statin drugs have been recognized to regulate T-cell function, statins also have been demonstrated endothelia protection, but whether this combination therapy was able to improve the efficacy remains unknown. Therefore, we designed this prospective, single-arm, open-label trial to investigate the efficacy of imatinib-based combination therapy in the treatment of SR-cGVHD for the first time.

METHODS

Sixty SR-cGVHD patients were entered into this trial to investigate the combination of imatinib mesylate and atorvastatin calcium for the treatment of SR-cGVHD. The primary endpoint included the overall response rate (ORR) after 6 months of combined treatment. The secondary endpoints included an evaluation of survival, changes in T-cell subsets, and adverse events.

RESULTS

At baseline, 45% (27/60) of patients had moderate cGVHD, and 55.0% (33/60) of patients had severe cGVHD. At the 6-month follow-up, a clinical response was achieved in 70.0% of patients, and a complete response (CR) was achieved in 26.7%. A total of 11.7% (7/60) of patients stopped immunosuppressive therapy at this point. After 6 months of treatment, the ORR rates of the liver, skin, eyes, and oral cavity were 80.6%, 78.1%, 61.5%, and 60.9%, respectively, with the liver also having the highest CR of 58.1%. The patients with moderate cGVHD had a better CR rate than those with severe cGVHD (55.6% vs. 3.0%, p < 0.0001). The overall survival in patients with ORR was improved (p = 0.0106). Lung involvement is an independent risk factor to affected ORR achievement (p = 0.021, HR = 0.335, 95% CI: 0.133-0.847), and the dosage of steroids was reduced in ORR patients. In clinical response patients, the ratio of CD8+ T cells (p = 0.0117) and Th17 cells (p = 0.0171) decreased, while the number of Treg cells (p = 0.0147) increased after 3 months. The most common adverse events were edema, nausea, and neutropenia, which were 13.3%, 11.7%, and 11.7%, respectively.

CONCLUSION

Combination treatment with imatinib mesylate and atorvastatin calcium was effective in treating SR-cGVHD and significantly decreased target organ injury, especially liver damage, indicating that T-cell regulatory function may play an important role in this process.

Rational Engineering of Islet Tolerance via Biomaterial-Mediated Immune Modulation

Type 1 diabetes (T1D) onset is characterized by an autoimmune attack on β islet cells within the pancreas, preventing the insulin secretion required to maintain glucose homeostasis. Targeted modulation of key immunoregulatory cell populations is a promising strategy to restore tolerance to β cells. This strategy can be used to prevent T1D onset or reverse T1D with transplanted islets. To this end, drug delivery systems can be employed to transport immunomodulatory cargo to specific cell populations that inhibit autoreactive T cell-mediated destruction of the β cell mass. The rational engineering of biomaterials into nanoscale and microscale drug carriers can facilitate targeted interactions with immune cells. The physicochemical properties of the biomaterial, the delivered immunomodulatory agent, and the target cell populations are critical variables in the design of these delivery systems. In this review, we discuss recent biomaterials-based drug delivery approaches to induce islet tolerance and the need to consider both immune and metabolic markers of disease progression.

TFNR2 in Ischemia-Reperfusion Injury, Rejection, and Tolerance in Transplantation

Tumor necrosis factor receptor 2 (TNFR2) has been shown to play a crucial role in CD4+ T regulatory cells (CD4+Tregs) expansion and suppressive function. Increasing evidence has also demonstrated its role in a variety of immune regulatory cell subtypes such as CD8+ T regulatory cells (CD8+ Tregs), B regulatory cells (Bregs), and myeloid-derived suppressor cells (MDSCs). In solid organ transplantation, regulatory immune cells have been associated with decreased ischemia-reperfusion injury (IRI), improved graft survival, and improved overall outcomes. However, despite TNFR2 being studied in the context of autoimmune diseases, cancer, and hematopoietic stem cell transplantation, there remains paucity of data in the context of solid organ transplantation and islet cell transplantation. Interestingly, TNFR2 signaling has found a clinical application in islet transplantation which could guide its wider use. This article reviews the current literature on TNFR2 expression in immune modulatory cells as well as IRI, cell, and solid organ transplantation. Our results highlighted the positive impact of TNFR2 signaling especially in kidney and islet transplantation. However, further investigation of TNFR2 in all types of solid organ transplantation are required as well as dedicated studies on its therapeutic use during induction therapy or treatment of rejection.

Retention of Donor T Cells in Lymphohematopoietic Tissue and Augmentation of Tissue PD-L1 Protection for Prevention of GVHD While Preserving GVL Activity

Allogeneic hematopoietic cell transplantation (Allo-HCT) is a curative therapy for hematological malignancies (i.e., leukemia and lymphoma) due to the graft-versus-leukemia (GVL) activity mediated by alloreactive T cells that can eliminate residual malignant cells and prevent relapse. However, the same alloreactive T cells can cause a serious side effect, known as graft-versus-host disease (GVHD). GVHD and GVL occur in distinct organ and tissues, with GVHD occurring in target organs (e.g., the gut, liver, lung, skin, etc.) and GVL in lympho-hematopoietic tissues where hematological cancer cells primarily reside. Currently used immunosuppressive drugs for the treatment of GVHD inhibit donor T cell activation and expansion, resulting in a decrease in both GVHD and GVL activity that is associated with cancer relapse. To prevent GVHD, it is important to allow full activation and expansion of alloreactive T cells in the lympho-hematopoietic tissues, as well as prevent donor T cells from migrating into the GVHD target tissues, and tolerize infiltrating T cells via protective mechanisms, such as PD-L1 interacting with PD-1, in the target tissues. In this review, we will summarize major approaches that prevent donor T cell migration into GVHD target tissues and approaches that augment tolerization of the infiltrating T cells in the GVHD target tissues while preserving strong GVL activity in the lympho-hematopoietic tissues.