Tai-Gyu Kim

Background: Antibodies against non-HLA antigens, such as MICA and MICB, have emerged as potential contributors to antibody-mediated rejection and graft failure. While MICA antibodies are well characterized, MICB-specific antibodies remain poorly understood due to the lack of standardized detection tools. To address this gap, we aimed to develop a cell-based platform expressing individual MICB antigens to evaluate the feasibility of detecting allele-specific anti-MICB antibodies in pre-kidney transplant sera. Methods: HLA class I, MICA, and MICB-null human embryonic kidney (HEK)-293T cells were previously generated by CRISPR/Cas9. We established five cell lines expressing single MICB antigens (each MICB*002, *003, *004, *005:02, and *008 allele). A total of 64 pre-kidney transplant sera were tested to assess anti-MICB antibody responses to the five cell lines using flow cytometry. Results: We successfully established and validated five HEK-293T cell lines each expressing a single MICB antigen using anti-MICB monoclonal antibody staining. No anti-MICB antibodies were detected in any of the 64 pre-transplant sera tested. This finding may reflect a low incidence of sensitization to MICB in this patient population and suggests the need for larger, more diverse cohorts in future studies to fully assess the prevalence of anti-MICB responses. The established cell lines provide a promising tool for future investigation of allele-specific anti-MICB antibody responses. Conclusions: While the present study did not detect allele-specific anti-MICB antibody responses, establishing HEK-293T cell lines expressing single MICB antigens represents a significant methodological advance. This platform enables the potential assessment of immune responses targeted to individual MICB allotypes, thus offering new avenues for the future study of MICB immunogenicity in transplantation settings.

Background: The reactivation and loss of mosaicism hypothesis due to X chromosome inactivation (XCI) skewing and escape could influence gender differences in autoimmune diseases. XCI selectively inactivates one of the two X chromosomes in females. Methods: To estimate XCI skewing and the occurrence of XCI escape, we conducted a normal female (NF) without a history of autoimmune thyroid disease (AITD) and a patient with Grave’s disease (GD) based on a thyroid diagnosis. After single-cell RNA sequencing, heterozygous variants were converted and transformed. XCI skewing was calculated using the formula and the skewing degree was defined. NF/GD genes were compared using correction methods. Positions are heterozygous within a single cell as indicated by a unique barcode. Results: XCI skewing showed 45.8%/48.9% relatively random, 29.4%/27.0% skewing, 24.6%/23.7% severe skewing, and 0.2%/0.4% extreme severe skewing. 24.8%/24.1% in NF/GD exhibited severe skewing or higher. A total of 13 genes were significantly associated with XCI skewing ratios in NF/GD cells. In total, 371/250 nucleotide positions with only one barcode (representing a unique cell) were identified for XCI escape. A total of 143/52 nucleotide positions spanned 20/6 genes, and 12/1 genes were identified as XCI escapes. Conclusions: These results could aid in understanding the immunogenetics of gender differences in various autoimmune disease pathophysiologies.

Turner syndrome (TS) can be determined by karyotype analysis, marked by the loss of one X chromosome in females. However, the genes involved in autoimmunity in TS patients remain unclear. In this study, we aimed to analyze differences in immune gene expression between a patient with TS, a healthy female, and a female patient with Graves’ disease using single-cell RNA sequencing (scRNA-seq) analysis of antigen-specific CD4(+) T cells. We identified 43 differentially expressed genes in the TS patient compared with the healthy female and the female patient with Graves’ disease. Many of these genes have previously been suggested to play a role in immune system regulation. This study provides valuable insights into the differences in immune-related gene expression between TS patients, healthy individuals, and those with autoimmune diseases.

Haeyoun Choi, Eun-Jeong Choi, Hyoung-Jae Kim, In-Cheol Baek, Aegyeong Won, Su Jin Park, Tai-Gyu Kim, Yeun-Jun Chung. Clin Transplant Res -0001;0:. https://doi.org/10.4285/ctr.24.0055

Introduction: Previously, we achieved large-scale expansion of bone marrow-derived suppressor cells (MDSCs) derived from cluster of differentiation (CD)34⁺ cells cultured in human umbilical cord blood (hUCB) and demonstrated their immunomodulatory properties. In the present study, we assessed the therapeutic efficacy of hUCB-MDSCs in atopic dermatitis (AD).Methods: Dermatophagoides farinae (Df)-induced NC/Nga mice (clinical score of 7) were treated with hUCB-MDSCs or a control drug. The mechanisms underlying the therapeutic effects of hUCB-MDSCs were evaluated.Results and discussion: hUCB-MDSCs demonstrated immunosuppressive effects in both human and mouse CD4⁺ T cells. hUCB-MDSCs significantly reduced the clinical severity scores, which were associated with histopathological changes, and reduced inflammatory cell infiltration, epidermal hyperplasia, and fibrosis. Furthermore, hUCB-MDSCs decreased the serum levels of immunoglobulin E, interleukin (IL)-4, IL-5, IL-13, IL-17, thymus- and activation-regulated chemokines, and thymic stromal lymphopoietin. Additionally, they altered the expression of the skin barrier function-related proteins filaggrin, involucrin, loricrin, cytokeratin 10, and cytokeratin 14 and suppressed the activation of Df-restimulated T-cells via cell–cell interactions. hUCB-MDSCs promoted skin recovery and maintained their therapeutic effect even after recurrence. Consequently, hUCB-MDSC administration improved Df-induced AD-like skin lesions and restored skin barrier function. Our findings support the potential of hUCB-MDSCs as a novel treatment strategy for AD.

Background: Middle East respiratory syndrome (MERS) is a lower respiratory tract disease caused by a beta coronavirus (CoV) called MERS-CoV, characterized by a high mortality rate. We aimed to evaluate the association between genetic variation in killer cell immunoglobulin-like receptors (KIRs) and the risk of MERS in South Koreans. Methods: KIR genes were genotyped by multiplex polymerase chain reaction with sequence-specific primers (PCR-SSP). A case-control study was performed to identify the odds ratios (OR) of KIR genes for MERS and the association of KIR genes and their ligands, human leukocyte antigens (HLA) genes. Results: KIR2DS4D and KIR3DP1F showed higher frequencies in the group of all patients infected with MERS-CoV than in the control group (p = 0.023, OR = 2.4; p = 0.039, OR = 2.7). KIR2DL1, KIR2DP1, and KIR3DP1D were significantly associated with moderate/mild (Mo/Mi) cases. KIR2DL2, KIR2DS1, and KIR3DP1F were affected in severe cases. When we investigated the association between KIR genes and their ligands in MERS patient and control groups, KIR3DL1+/Bw4(80I)+, KIR3DL1+/Bw6+, KIR3DL1+/Bw6−, KIR2DS1+/C2+, and KIR3DS+/Bw4(80I)+ were associated with MERS. KIR3DL1+/Bw6− was found in Mo/Mi cases. KIR2DS1+/C2+ and KIR2DS2+/C1+ were found in severe cases. Conclusion: Further investigations are needed to prove the various immune responses of MERS-CoV-infected cells according to variations in the KIR gene and ligand gene. A treatment strategy based on current research on the KIR gene and MERS-CoV will suggest potential treatment targets.

Chemokines are chemotactic cytokines that can cause directed migration of leukocytes. The aim of this study was to examine differences in single nucleotide polymorphisms (SNP) of chemokine in AITD patients compared to normal controls. A total of 86 Korean pediatric patients were included in the patient group and 183 adults were included in the normal control group. To compare influences of several chemokine gene polymorphisms, 25 SNPs in 16 chemokine genes were analyzed. Genotype frequencies of CCL11(rs3744508)AA(OR = 6.9) and CCR2(rs1799864)AA(OR = 3.8) were higher in the AITD patients than in the controls, whereas CCL17(rs223828)CC was lower in the AITD patients than in the controls(OR = 0.4). In comparison between Graves' disease (GD) patients and controls, genotype frequency of CCL17(rs223828)CC(OR = 0.4) was lower in the GD group, whereas those of CCR2(rs1799864)AA(OR = 4.8) were higher in the GD group. The genotype frequency of CCL11(rs3744508)AA(OR = 11.3) was higher in Hashimoto's thyroiditis (HT) patients, whereas that of CXCL8(rs2227306)CC(OR = 0.4) was lower in HT patients. Polymorphisms of CCL11(rs3744508), CCL17(rs223828), and CCR2(rs1799864) might be associated with AITD, with CCL17(rs223828), CCR2(rs1799864) and CXCR2(rs2230054, rs1126579) affecting GD and CCL11(rs3744508) and CXCL8(rs2227306) affecting HT in Korean children.

Killer‐cell immunoglobulin‐like receptors (KIR) control natural killer (NK) cell functions by recognizing HLA molecules and modulating the activity of NK cells. The KIR gene cluster contains polymorphic and highly homologous genes. Diversity of the KIR region is achieved through differences in gene content, allelic polymorphism, and gene copy number, which result in unrelated individuals having different KIR genotypes and individualized immune responses that are relevant to multiple aspects of human health and disease. Therefore, KIR genotyping is increasingly used in epidemiological studies. Here, we developed multiplex polymerase chain reaction with sequence‐specific primers (PCR‐SSP) to compensate for the shortcomings of the conventional PCR‐SSP method, which is most commonly used for KIR analysis. Multiplex PCR‐SSP method involves six multiplex reactions that detect 16 KIR genes and distinguish variant types of some KIR genes by adding two reactions. The assay was evaluated in a blind survey using a panel of 40 reference DNA standards from the UCLA KIR Exchange Program. The results are 100% concordant with the genotype determined using Luminex‐based reverse sequence‐specific oligonucleotide typing systems. Additionally, we investigated the currently known 16 KIR genes and their common variants in 120 unrelated Korean individuals. The results were consistent with the KIR genotype previously reported by Hwang et al. This multiplex PCR‐SSP is an efficient method for analyzing KIR genotypes in both small‐ and large‐scale studies with minimal labor, reagents, and DNA. Furthermore, by providing a better definition of KIR polymorphisms it can contribute to developments in immunogenetics.

Purpose: The immune responses of natural killer (NK) cells against cancer cells vary by patient. Killer Ig-like receptors (KIRs), which are some of the major receptors involved in regulating NK cell activity for killing cancer cells, have significant genetic variation. Numerous studies have suggested a potential association between the genetic variation of KIR genes and the risk of development or prognosis of various cancer types. However, an association between genetic variations of KIR genes and glioblastoma (GB) remains uncertain. We sought to evaluate the association of genetic variations of KIRs and their ligand genes with the risk of GB development in Koreans. Methods: A case–control study was performed to identify the odds ratios (ORs) of KIR genes and Classes A, B, and, C of the human leukocyte antigen (HLA) for GB. The GB group was comprised of 77 patients with newly diagnosed IDH-wildtype GB at our institution, and the control group consisted of 200 healthy Korean volunteers. Results: There was no significant difference in the frequency of KIR genes and KIR haplotypes between the GB and control groups. Genetic variations of KIR-2DL1, 3DL1, and 3DS1 with their ligand genes (HLA-C2, HLA-Bw4/6, and Bw4, respectively) had effects on the risk of GB in Korean patients. The frequency of KIR-2DL1 with HLA-C2 (OR 2.05, CI 1.19–3.52, p = 0.009), the frequency of KIR-3DL1 without HLA-Bw4 (80I) (OR 8.36, CI 4.06–17.18, p < 0.001), and the frequency of KIR-3DL1 with Bw6 (OR 4.54, CI 2.55–8.09, p < 0.001) in the GB group were higher than in the control group. In addition, the frequency of KIR-2DL1 without HLA-C2 (OR 0.44, CI 0.26–0.75, p = 0.003), the frequency of KIR-3DL1 with HLA-Bw4 (80T) (OR 0.13, CI 0.06–0.27, p < 0.001), the frequency of KIR-3DL1 without Bw6 (OR 0.27, CI 0.15–0.49, p < 0.001), and the frequency of KIR-3DS1 with Bw4 (80I) (OR 0.03, CI 0.00–0.50, p < 0.001) in the GB group were lower than in the control group. Conclusions: This study suggests that genetic variations of KIRs and their ligand genes may affect GB development in the Korean population. Further investigations are needed to demonstrate the different immune responses for GB cells according to genetic variations of KIR genes and their ligand genes.

Background: CD40L is primarily expressed on activated CD4⁺ T cells and binds to CD40 which is expressed by various cells including dendritic cells, macrophages and B lymphocytes. While CD40-CD40L interaction is known to be direct between B cells and CD4⁺ T cells which results in proliferation and immunoglobulin isotype switching, antigen presenting cells (APCs) were thought to be involved in the delivery of CD4⁺ help to CD8⁺ T cells by cross-talk between CD4⁺ and CD8⁺ T cells and APCs. However, subsequent study demonstrated that CD40L signal can be directly delivered to CD8⁺ T cells by CD40 expression on CD8⁺ T cells. Since most studies have been carried out in murine models, we aimed to investigate the direct effect of CD40L on human peripheral CD8⁺ T cells. Results: Human peripheral CD8⁺ T cells were isolated to exclude the indirect effect of B cells or dendritic cells. Upon activation, CD40 expression on CD8⁺ T cells was transiently induced and stimulation with artificial APCs expressing CD40L (aAPC-CD40L) increased the number of total and central memory CD8⁺ T cells and also pp65 specific CD8⁺ T cells. Stimulation with aAPC-CD40L also resulted in higher proportion of central memory CD8⁺ T cells. Conclusions: Our study suggests that CD40L has an effect on the increased number of CD8⁺ T cells through CD40 expressed on activated CD8⁺ T cells and has influence on memory CD8⁺ T cell generation. Our results may provide a new perspective of the effect of CD40L on human peripheral CD8⁺ T cells, which differ according to the memory differentiation status of CD8⁺ T cells.