Dong-Gyun Lim

Interleukin (IL)-10 Induced by CD11b + Cells and IL-10-Activated Regulatory T Cells Play a Role in Immune Modulation of Mesenchymal Stem Cells in Rat Islet Allografts

Mesenchymal stem cells (MSCs) are suggested to be immune modulators because of their therapeutic potential in transplantation. In the present study, we evaluated the therapeutic potential of autologous MSCs for preventing graft rejection after allogeneic rat islet transplantation. We assessed the ability of MSCs to elicit an antiproliferative response in alloreactive lymphocytes and tested the immunosuppressive effect of MSCs in allogeneic islet transplantation. In islet allotransplantation, injection of autologous MSCs or a subtherapeutic dose of cyclosporine A (CsA; 5 mg/kg) alone did not prolong allograft survival. However, graft survival was attained for >100 d in 33% of autologous MSC-plus-CsA-treated recipients, indicating that graft acceptance was achieved in a subgroup of allograft recipients. Splenocytes from autologous MSC-plus-CsA-treated rats exhibited a reduced mixed lymphocyte reaction (MLR)-proliferative response to donor stimulators and increased interleukin (IL)-10 release. Interestingly after excluding host CD11b+ cells, splenic T cells from autologous MSC-plus-CsA-treated rats did not produce IL-10 or did not inhibit proliferative responses under the same conditions. The use of autologous MSC-plus-CsA downregulated immune responses, inducing donor-specific T-cell hyporesponsiveness by reducing the production of proinflammatory cytokines and inducing antiinflammatory cytokine production, especially that of IL-10, during the early posttransplantation period. T-regulatory cells made a contribution at a later phase. In conclusion, the combined use of autologous MSCs and low-dose CsA exerted a synergistic immunosuppressive effect in an islet allograft model, suggesting a role for autologous MSCs as an immune modulator.

Impact of immunosuppressants on the therapeutic efficacy of in vitro-expanded CD4+CD25+Foxp3+ regulatory T cells in allotransplantation.

Background. Although the therapeutic potential of regulatory T lymphocytes (Tregs) in preventing allograft rejection has been well documented, accumulating evidence indicates that supplemental measures, such as concomitant use of immunosuppressive agents, are essential for effective application of Treg cell therapy in clinical transplantation. Thus, it is important to know the effect of immunosuppressive agents on Treg cell therapy. Methods. We examined the impact of various immunosuppressive agents on the in vivo proliferation and therapeutic efficacy of in vitro-expanded Tregs using the murine graft-versus-host reaction and skin allograft model (BDF1 [H-2b/d] to C57BL/6 [H-2b]), respectively. Results. All six immunosuppressive agents tested inhibited the alloantigen-stimulated proliferation of Tregs as efficiently as they inhibited the proliferative response of conventional CD3+ T cells. We further show that blockade of the CD40-CD40L interaction by treatment with a MR-1 antibody significantly increased the therapeutic efficacy of Tregs, a synergistic effect that seemed to be related to the strong regulatory activity of adoptively transferred Tregs together with effector T-cell hyporesponsiveness. Although concomitant use of rapamycin marginally augmented the therapeutic effectiveness of Tregs, mycophenolate mofetil and cyclosporine A at their full therapeutic doses exerted an antagonistic effect on Treg cell therapy. Conclusion. These results demonstrate that inhibition of CD40-CD40L interaction or treatment with rapamycin could be successfully combined with in vitro-expanded Treg cell therapy, but the concomitant use of mycophenolate mofetil or cyclosporine A in this type of Treg cell therapy should be carefully considered.

Viral IL-10 gene transfer prolongs rat islet allograft survival.

Islet transplantation is a potential cure for diabetes. However, allotransplant rejection severely limits its clinical application. In this study, we sought to transfect rat islets with an adenoviral vector containing the viral IL-10 (vIL-10) gene and examine its efficacy in preventing graft rejection. The immunosuppressive effect of vIL-10 is reported but its efficacy is somehow debatable in transplantation model. vIL-10 transfected islets were transplanted into streptozotocin-induced diabetic rats. Blood glucose, serum vIL-10 concentration, graft histology, and graft cytokine expression were used to monitor graft function up to day 21 after transplantation. Transfected islets released a large amount of vIL-10 protein without affecting their viability and functional integrity. When we transplanted the transfected islets into allogeneic hosts, the survival of grafted islets was not significantly increased. However, the combined use of vIL-10 and subtherapeutic doses of CsA (cyclosporine) significantly prolonged graft survival beyond that achieved with either agent alone (p < 0.001). vIL-10 and CsA-treated rats contain high level of vIL-10 in serum, which is evidenced by the inhibition of allogeneic mixed lymphocyte reaction (MLR). Histological analysis additionally revealed the presence of viable islets up to 21 days. IL-10 mRNA expression in grafted liver was higher and IFN-γ mRNA was lower in vIL-10 and CsA-treated animals, compared with other groups. The synergistic effect of this combination therapy is potentially correlated with the induction of inhibitory cytokine secretion and downregulation of proinflammatory cytokine secretion from host cells.

An effective immune-monitoring protocol based on gene expression profiles in the peripheral T-cell fraction reactive to graft antigens.

Background The ability to induce tolerance, or at least minimize the need for immunosuppressive therapy, is a high priority in organ transplantation. Accomplishing this goal requires a novel method for determining when a patient has become tolerant to or is rejecting their graft. Here, we sought to develop an efficient monitoring protocol based on gene expression profiles of recipient T cells in murine skin and islet allograft models. Methods Unlike previous studies, here, gene expression analysis was focused on donor antigen-reactive T cells, which were prepared by collecting CD69+ T cells from cocultures of recipient peripheral T cells and donor antigen-presenting cells. Candidate tolerance and rejection biomarker genes were selected from a CD69+ T-cell microarray analysis, and their expression levels were measured in the recipient CD69+ T-cell fraction using quantitative reverse transcription polymerase chain reaction. Results Our new monitoring protocol was capable of precisely detecting the immune status of recipients relative to their graft regardless of the organ received, whether they were taking immunosuppressive drugs, or different strains of origin. Conclusions Gene expression analysis focusing on recipient CD69+ T cells as the donor antigen-reactive T-cell population could be used as an effective and sensitive method for monitoring transplant patients.

A Middle East respiratory syndrome screening clinic for health care personnel during the 2015 Middle East respiratory syndrome outbreak in South Korea: A single-center experience

Background: Transmission of Middle East respiratory syndrome (MERS) to health care personnel (HCP) is a major concern. This study aimed to review cases of MERS‐related events, such as development of MERS‐like symptoms or exposure to patients. Methods: A MERS screening clinic (MSC) for HCP was setup in the National Medical Center during the MERS outbreak in 2015. Clinical and laboratory data from HCP who visited the MSC were retrospectively reviewed. Additionally, these data were compared with the results of postoutbreak questionnaire surveys and interviews about MERS‐related symptoms and risk‐related events. Results: Of the 333 HCP who participated in MERS patient care, 35 HCP (10.5%) visited the MSC for MERS‐like symptoms. No one was infected with MERS, and the most common symptom was fever (68.6%) followed by cough (34.3%). However, 106 of 285 postoutbreak survey participants experienced at least 1 MERS‐related symptom and 26 reported exposure to patients without appropriate personal protective equipment, whereas only 4 HCP visited the MSC to report exposure events. Conclusions: Although a considerable number of HCP experienced MERS‐related symptoms or unprotected exposure during MERS patient care, some did not take appropriate action. These findings imply that for infection control strategy to be properly performed, education should be strengthened so that HCP can accurately recognize the risk situation and properly notify the infection control officer.

Differential expression of CD57 in antigen-reactive CD4+ T cells between active and latent tuberculosis infection.

The development of diagnostic tests that predict the progression of latent tuberculosis infection to active disease is pivotal for the eradication of tuberculosis. As an initial step to achieve this goal, our studys aim was to identify biomarkers that differentiate active from latent tuberculosis infection. We compared active and latent tuberculosis infection groups in terms of the precursor frequency, functional subset differentiation, and senescence/exhaustion surface marker expression of antigen-specific CD4(+) T cells, which were defined as dividing cells upon their encountering with Mycobacterium (M.) tuberculosis antigens. Among several parameters shown to have statistically significant differences between the two groups, the frequency of CD57-expressing cells could differentiate effectively between active disease and latent infection. Our results suggest that the expression of CD57 in M. tuberculosis-reactive CD4(+) T cells could be a promising candidate biomarker with which to identify individuals with latent tuberculosis infection prone to progression to active disease.

Immune Responses to Middle East Respiratory Syndrome Coronavirus During the Acute and Convalescent Phases of Human Infection

Abstract Background An understanding of immune responses against the Middle East respiratory syndrome (MERS) is important for the development of treatments and preventive measures. Here, we investigated the spectrum of immune responses occurring in patients with MERS during the early period of infection. Methods We obtained peripheral blood samples from 27 hospitalized patients recruited during the epidemic that occurred in 2015 in South Korea. Plasma cytokines/chemokines and antibodies were quantified. Virus-specific T cells were examined by intracellular cytokine staining after stimulation of peripheral blood mononuclear cells with overlapping peptides spanning whole virus structural proteins. Results At the acute phase of infection, elevated levels of plasma proinflammatory cytokines/chemokines were detected in proportion to the severity of the disease. Distinctively high frequencies of MERS coronavirus–reactive CD8+ T cells were also observed in patients with severe/moderate illness, whereas antibody and CD4+ T-cell responses were minimally detected at this stage. At the convalescent phase, disease severity–dependent antibody responses emerged and antigen-reactive cells were identified in both T-cell subsets. These T cells belonged to the T-helper 1 or type 1 cytotoxic T cell subtypes. While CD8+ T cells responded preferentially to the viral S protein compared with E/M/N proteins, especially at the acute stage, slightly more CD4+ T cells recognized E/M/N proteins compared with S protein at the convalescent phase. Conclusions Our findings show an association between the early CD8+ T-cell response and the severity of the infection, and also provide basic information that may help to prepare effective control strategies for MERS in humans.

Diagnostic value of tolerance-related gene expression measured in the recipient alloantigen-reactive T cell fraction

The efficient development of tolerance-inducing therapies and safe reduction of immunosuppression should be supported by early diagnosis and prediction of tolerance in transplantation. Using mouse models of donor-specific tolerance to allogeneic skin and islet grafts we tested whether measurement of tolerance-related gene expression in their alloantigen-reactive peripheral T cell fraction efficiently reflected the tolerance status of recipients. We found that Foxp3, Nrn1, and Klrg1 were preferentially expressed in conditions of tolerance compared with rejection or unmanipulated controls if their expression is measured in CD69(+) T cells prepared from coculture of recipient peripheral T cells and donor antigen-presenting cells. The same pattern of gene expression was observed in recipients grafted with either skin or islets, recipients of different genetic origins, and even those taking immunosuppressive drugs. These findings suggest that the expression of tolerance-related genes in the alloantigen-reactive T cell fraction could be used to detect tolerance in the clinic.