Sun Woo Lim

Sodium-glucose cotransporter-2 inhibitors (SGLT2is) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) are widely used in type 2 diabetes mellitus for glycemic control and organ protection. This study investigated whether the combined use of empagliflozin (EMPA) and liraglutide (LIRA) could protect against pancreatic and renal damage caused by tacrolimus (TAC). Male Sprague-Dawley rats received TAC for 4 weeks, either alone, or in combination with EMPA, LIRA, or both. Metabolic, histologic, and molecular parameters were assessed in vivo and in vitro. TAC caused hyperglycemia, reduced creatinine clearance, pancreatic β-cell loss, renal tubulointerstitial fibrosis, and increased oxidative stress and apoptosis. Either EMPA or LIRA alone partially attenuated these changes, whereas their combination provided enhanced protection- improving kidney function, preserving islet integrity, and reducing fibrosis and cell death. In the kidney and pancreas, dual therapy restored antiapoptotic and antioxidant signaling while suppressing profibrotic pathways, thereby mitigating oxidative stress and injury. Cell-based experiments further confirmed that EMPA plus LIRA enhanced cell viability and reduced reactive oxygen species generation in TAC-injured HK-2 and INS-1 cells. These findings indicate that combined SGLT2i and GLP-1RA therapy confers additive metabolic protection associated with attenuation of oxidative stress in tacrolimus-induced pancreatic and renal damage in this preclinical model, warranting further investigation of its potential as an adjunct strategy for posttransplant diabetes mellitus and nephrotoxicity.

X-linked Alport syndrome (XLAS) is an inherited nephropathy caused by pathogenic COL4A5 variants that lead to podocyte dysfunction and progressive kidney failure. However, the involvement of endoplasmic reticulum (ER) stress and oxidative stress in the development of XLAS remains insufficiently understood. This study aims to elucidate the contribution of ER and oxidative stress to podocyte injury in XLAS employing a patient-derived human induced pluripotent stem cell (hiPSC)-based podocyte model. Induced pluripotent stem cells were derived from XLAS patient blood cells and differentiated into podocytes (XLAS podocyte). Expression of pluripotency, lineage-specific, and podocyte markers was confirmed. ER stress, oxidative stress, and mitochondrial morphology were assessed through molecular characterization, imaging, and functional assays, comparing XLAS podocytes to wild-type (WT) hiPSC-derived podocytes. XLAS patient-derived hiPSCs maintained typical pluripotency markers, exhibited normal karyotypes, and allowed for successful tri-lineage differentiation. Relative to WT podocytes, XLAS podocytes had diminished expression of NPHS1, WT1, and COL4A5, while COL4A1 was increased. ER stress marker expression was elevated, with lower levels of CANX and CALR, indicative of unfolded protein response (UPR) activation. Electron microscopy analysis demonstrated enhanced ER enlargement in XLAS podocyte, implicating ER stress in disease pathogenesis. Moreover, XLAS podocytes showed markedly raised oxidative stress markers and mitochondrial reactive oxygen species (ROS) levels, together with altered catalase protein expression. Viability assays further supported ER and oxidative stress as contributors to reduced podocyte survival in XLAS podocyte. Our findings indicate that ER stress and oxidative stress are critical drivers of podocyte dysfunction in XLAS. UPR activation, ROS accrual, and mitochondrial impairment point to important therapeutic opportunities.

This study aims to investigate the effects of complete SLC12A3 gene knock-in using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) in human-induced pluripotent stem cells (hiPSCs), focusing on cellular characteristics and functional implications in the context of Gitelman syndrome. Employing CRISPR/Cas9 gene-editing technology, the SLC12A3 gene was integrated into WTC-11 hiPSCs, resulting in the creation of the WTC-11SLC12A3-KI cell line. Successful integration was confirmed through green fluorescence protein (GFP) reporter gene expression, and SLC12A3 expression was verified via polymerase chain reaction, flow cytometry, immunoblotting, and immunofluorescence in kidney organoids. Functional analysis with the intracellular sodium indicator CoroNa Green dye (Invitrogen) assessed the impact of SLC12A3 gene knock-in and thiazides. The WTC-11SLC12A3-KI hiPSCs exhibited successful integration of the SLC12A3 gene, with enhanced SLC12A3 expression evidenced by GFP and SLC12A3 proteins compared to WTC-11 hiPSCs. Upon differentiation into kidney organoids, the WTC-11SLC12A3-KI organoids displayed increased GFP, SLC12A3 expression, and the associated WNK-SPAK/OSR1 signaling cascade relative to WTC- 11 organoids. The intracellular sodium flux was stimulated by angiotensin II treatment in kidney organoid cells and attenuated by thiazides in both WTC-11 and WTC-11SLC12A3-KI groups. This study indicates that the knock-in of the SLC12A3 gene could serve as a therapeutic strategy for Gitelman syndrome.

Lee S, et al. J Korean Med Sci. 2026 Jan;41(3):e37. https://doi.org/10.3346/jkms.2026.41.e37

Background: The aim of this study is to investigate the specific pathway involved in human leukocyte antigen (HLA) sensitization using single-cell RNA-sequencing analysis and an allo-sensitized mouse model developed with an HLA.A2 transgenic mouse. Methods: For sensitization, wild-type C57BL/6 mouse received two skin grafts from C57BL/6-Tg(HLA-A2.1)1Enge/J mouse (allogeneic mouse, ALLO). For syngeneic control (SYN), skin grafts were transferred from C57BL/6 to C57BL/6. We performed single-cell RNA-sequencing analysis on splenocytes isolated from ALLO and SYN and compared the gene expression between them.Results: We generated 9,190 and 8,890 single-cell transcriptomes from ALLO and SYN, respectively. Five major cell types (B cells, T cells, natural killer cells, macrophages, and neutrophils) and their transcriptome data were annotated according to the representative differentially expressed genes of each cell cluster. The percentage of B cells was higher in ALLO than it was in SYN. Kyoto Encyclopedia of Genes and Genomes enrichment analyses indicated that the highly expressed genes in the B cells from ALLO were mainly associated with antigen processing and presentation pathways, allograft rejection, and the Th17 cell differentiation pathway. Upregulated genes in the T cells of ALLO were involved in the interleukin (IL)-17 signaling pathway. The ratio of Th17 cluster and Treg cluster was increased in the ALLO. On flow cytometry, the percentage of Th17 (IL-17+/CD4+ T) cells was higher and regulatory T cells (FOXP3+/CD4+ T) was lower in the ALLO compared to those in the SYN.Conclusion: Our results indicate that not only the B cell lineage but also the Th17 cells and their cytokine (IL-17) are involved in the sensitization to HLA.

Woo JS, et al. Immune Netw. 2025 Dec;25(6):e41. https://doi.org/10.4110/in.2025.25.e41

Genetic or hereditary kidney disease stands as a pivotal cause of chronic kidney disease (CKD). The proliferation and widespread utilization of DNA testing in clinical settings have notably eased the diagnosis of genetic kidney diseases, which were once elusive but are now increasingly identified in cases previously deemed CKD of unknown etiology. However, despite these diagnostic strides, research into disease pathogenesis and novel drug development faces significant hurdles, chiefly due to the dearth of appropriate animal models and the challenges posed by limited patient cohorts in clinical studies. Conversely, the advent and utilization of human-induced pluripotent stem cells (hiPSCs) offer a promising avenue for genetic kidney disease research. Particularly, the development of hiPSC-derived kidney organoid systems presents a novel platform for investigating various forms of genetic kidney diseases. Moreover, the integration of the CRISPR/Cas9 technique into this system holds immense potential for efficient research on genetic kidney diseases. This review aims to explore the applications of in vitro kidney organoids generated from hiPSCs in the study of diverse genetic kidney diseases. Additionally, it will delve into the limitations of this research platform and outline future perspectives for advancing research in this crucial area.

Background: Multiple risk factors are involved in new-onset diabetes mellitus (DM) after organ transplantation; however, their ability to predict clinical prognosis remains unclear. Therefore, we investigated whether patient-specific induced pluripotent stem cells (iPSCs) could help predict DM development before performing kidney transplantation (KT). Methods: We first performed whole transcriptome and functional enrichment analyses of KT patient-derived iPSCs. Our results revealed that insulin resistance, type 2 DM, and transforming growth factor beta signaling pathways are associated between the groups of DM and non-DM. We next determined whether the genetic background was associated with development of iPSCs into pancreatic progenitor (PP) cells. Results: The levels of differentiation-related key markers of PP cells were significantly lower in the DM group than in the non-DM group. Moreover, the results of tacrolimus toxicity screening showed a significant decrease in the number of PP cells of the DM group compared with the non-DM group, suggesting that these cells are more susceptible to tacrolimus toxicity. Conclusion: Taken together, these results indicate that PP cells of the DM group showed low developmental potency accompanied by a significantly different genetic background compared with the non-DM group. Thus, genetic analysis can be used to predict the risk of DM before KT.

Sensitization to HLA can result in allograft loss for kidney transplantation (KT) patients. Therefore, it is required to develop an appropriate desensitization (DSZ) technique to remove HLA-donor-specific anti-HLA antibody (DSA) before KT. The aim of this research was to investigate whether combined use of the IL-6 receptor-blocking antibody, tocilizumab (TCZ), and bone-marrow-derived mesenchymal stem cells (BM-MSCs) could attenuate humoral immune responses in an allo-sensitized mouse model developed using HLA.A2 transgenic mice. Wild-type C57BL/6 mice were sensitized with skin allografts from C57BL/6-Tg (HLA-A2.1)1Enge/J mice and treated with TCZ, BM-MSC, or both TCZ and BM-MSC. We compared HLA.A2-specific IgG levels and subsets of T cells and B cells using flow cytometry among groups. HLA.A2-specific IgG level was decreased in all treated groups in comparison with that in the allo-sensitized control (Allo-CONT) group. Its decrease was the most significant in the TCZ + BM-MSC group. Regarding the B cell subset, combined use of TCZ and BM-MSC increased proportions of pre-pro B cells but decreased proportions of mature B cells in BM (p < 0.05 vs. control). In the spleen, an increase in transitional memory was observed with a significant decrease in marginal, follicular, and long-lived plasma B cells (p < 0.05 vs. control) in the TCZ + BM-MSC group. In T cell subsets, Th2 and Th17 cells were significantly decreased, but Treg cells were significantly increased in the TCZ+BM-MSC group compared to those in the Allo-CONT group in the spleen. Regarding RNA levels, IL-10 and Foxp3 showed increased expression, whereas IL-23 and IFN-γ showed decreased expression in the TCZ + BM-MSC group. In conclusion, combined use of TCZ and BM-MSC can inhibit B cell maturation and up-regulate Treg cells, finally resulting in the reduction of HLA.A2-specific IgG in a highly sensitized mouse model. This study suggests that the combined use of TCZ and BM-MSC can be proposed as a novel strategy in a desensitization protocol for highly sensitized patients.

Karyomegalic interstitial nephritis (KIN) is a genetic kidney disease caused by mutations in the FANCD2/FANCI-Associated Nuclease 1 (FAN1) gene on 15q13.3, which results in karyomegaly and fibrosis of kidney cells through the incomplete repair of DNA damage. The aim of this study was to explore the possibility of using a human induced pluripotent stem cell (hiPSC)-derived kidney organoid system for modeling FAN1-deficient kidney disease, also known as KIN. We generated kidney organoids using WTC-11 (wild-type) hiPSCs and FAN1-mutant hiPSCs which include KIN patient-derived hiPSCs and FAN1-edited hiPSCs (WTC-11 ^FAN1+/−), created using the CRISPR/Cas9 system in WTC-11-hiPSCs. Kidney organoids from each group were treated with 20 nM of mitomycin C (MMC) for 24 or 48 h, and the expression levels of Ki67 and H2A histone family member X (H2A.X) were analyzed to detect DNA damage and assess the viability of cells within the kidney organoids. Both WTC-11-hiPSCs and FAN1-mutant hiPSCs were successfully differentiated into kidney organoids without structural deformities. MMC treatment for 48 h significantly increased the expression of DNA damage markers, while cell viability in both FAN1-mutant kidney organoids was decreased. However, these findings were observed in WTC-11-kidney organoids. These results suggest that FAN1-mutant kidney organoids can recapitulate the phenotype of FAN1-deficient kidney disease.