The Immunomodulating Effects of Thalidomide and Dexamethasone in a Murine Cardiac Allograft Transplantation Model

Purpose@#The immunomodulatory effects of thalidomide (TM) and dexamethasone (DX) on immune cells and their co-stimulatory, co-inhibitory molecules in vitro and in vivo have been previously reported. The current study investigated the effects of TM and the combinatorial treatment with DX on immune cells using a murine cardiac allograft transplantation model. @*Materials and Methods@#Intraabdominal transplant of cardiac allografts from BALB/c (H-2d ) donors to C57BL/6 (H-2b ) recipients was performed. After transplantation, mice were injected daily with TM or DX or a combination of both TM and DX (TM/DX) by intraperitoneal route until the time of graft loss. CD4+ T cell subsets and CD11c+ cells in the peripheral blood mononuclear cells and spleen were examined and quantified with flow cytometry. Serum IL-6 levels were measured by enzyme-linked immunosorbent assay on day 7. @*Results@#The mean graft survivals were 6.86 days in the untreated group, and 10.0 days in the TM/DX group (p<0.001). The TM/DX treatment affected the CD4+ T cell subsets without suppressing the total CD4+ T cell population. The CD4 + FOXP3+ /CD4+ CD44hi T cell ratio increased. Increase in cell counts and median fluorescence intensity on CD11c+ CD85k+ with TM/DX were observed. The inhibition of pro-inflammatory cytokine interleukin-6 was also observed. @*Conclusion@#These outcomes suggest the immunomodulating effect of the TM/DX combinatorial treatment. In conclusion, TM/ DX combination may be a promising immunomodulatory approach for preventing allograft rejection and improving graft survival by inducing tolerance in transplantation.

Systemic Immunomodulatory Effects of Combinatorial Treatment of Thalidomide and Dexamethasone on T Cells and Other Immune Cells

Purpose@#In organ transplantation, the need for immune modulation rather than immune suppression has been emphasized. In this study, we investigated whether combinatorial treatments of with thalidomide (TM) and dexamethasone (DX) might be new approaches to induce systemic immunomodulation on T cells and other immune cells that regulate the expression of co-inhibitory molecules. @*Materials and Methods@#Naïve splenic T cells from C57BL/6 mice were sort-purified and cultured in vitro for CD4+ T cell proliferation and regulatory T cell (Treg) conversion in the presence of TM or/and DX. Expression of cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and programmed death-1 (PD-1) in proliferated and converted T cells was quantified by flow cytometry. We also quantified in vivo expression of CTLA-4 and PD-1 on splenic CD4+ T cells and other immune cells isolated from TM- or/and DX-treated mice. Mixed lymphocytes reactions (MLR) were performed to evaluate the capacity of immune cells in carrying out immune responses. @*Results@#CTLA-4 expressions in effector T cells in vivo and in Tregs in vivo/vitro significantly increased upon TM/DX combinatorial treatment. Corresponding to increased CTLA-4 expression in T cells, the expression of ligand molecules for CTLA-4 significantly increased in splenic dendritic cells in TM/DX-treated groups. In addition, MLR results demonstrated that splenocytes isolated from TM/DX-treated mice significantly suppressed the proliferation of T cells isolated from other strains. @*Conclusion@#Based on these results, we suggest that TM/DX combinatorial treatments might be efficient immunomodulatory methods for regulating T cell immunity.

Metabolic Reprogramming by the Excessive AMPK Activation Exacerbates Antigen-Specific Memory CD8⁺ T Cell Differentiation after Acute Lymphocytic Choriomeningitis Virus Infection

During virus infection, T cells must be adapted to activation and lineage differentiation states via metabolic reprogramming. Whereas effector CD8⁺ T cells preferentially use glycolysis for their rapid proliferation, memory CD8⁺ T cells utilize oxidative phosphorylation for their homeostatic maintenance. Particularly, enhanced AMP-activated protein kinase (AMPK) activity promotes the memory T cell response through different pathways. However, the level of AMPK activation required for optimal memory T cell differentiation remains unclear. A new metformin derivative, IM156, formerly known as HL156A, has been reported to ameliorate various types of fibrosis and inhibit in vitro and in vivo tumors by inducing AMPK activation more potently than metformin. Here, we evaluated the in vivo effects of IM156 on antigen-specific CD8⁺ T cells during their effector and memory differentiation after acute lymphocytic choriomeningitis virus infection. Unexpectedly, our results showed that in vivo treatment of IM156 exacerbated the memory differentiation of virus-specific CD8⁺ T cells, resulting in an increase in short-lived effector cells but decrease in memory precursor effector cells. Thus, IM156 treatment impaired the function of virus-specific memory CD8⁺ T cells, indicating that excessive AMPK activation weakens memory T cell differentiation, thereby suppressing recall immune responses. This study suggests that metabolic reprogramming of antigen-specific CD8⁺ T cells by regulating the AMPK pathway should be carefully performed and managed to improve the efficacy of T cell vaccine.

Islet Encapsulation Using Chondrocyte / 대한이식학회지

Diabetes mellitus is one of the leading metabolic diseases that cause an increasing rate of mortality and morbidity. Recently, rather than the current drug treatment, pancreatic islet transplantation has been regarded as a potentially promising strategy for insulin- dependent diabetes mellitus while preventing complications such as kidney damage, vascular damage, nerve damage, and blindness. Recently, a number of advanced islet encapsulation techniques have been designed to enhance the efficiency of islet transplantation, including cell sheet engineering and generation of 3D islet spheroids by high density suspension system (HDSS). Chondrocytes derived from cartilage sources have been used as an encapsulation biomaterial for islets not only for autograft but also for allograft and xenograft transplantation. Cartilage is an avascular, white connective tissue that is rich in extracellular matrix, and expandable in vitro. Hence, this tissue might have immunologically privileged properties that make it an intelligent cell source for manufacture of encapsulation biomaterials. However, cell sheet engineering and HDSS still have their respective limitations, which need to be elucidated. This review will describe the advantages and disadvantages of the current encapsulation techniques in order to provide a comprehensive foundation for further modifications and improvements of tissue engineering for islet transplantation.