Biology subjects

Koh, T. J.

Publications and source records attributed to Koh, T. J..

5 recordsLinked to original sources

bioRxiv2026

Multi-omics analysis of type II diabetic wound healing reveals CD44-mediated immune cell crosstalk dysfunction in mice and humans

Type II diabetes mellitus (T2DM) is one of the most prevalent diseases in the United States and is associated with diabetic foot ulcers (DFU) and their impaired, often chronic, wound healing. The T2DM mouse model with dysfunctional leptin receptor (db/db) has been used in basic and translational studies of wound healing due to its systemic phenotypes (hyperphagia, hypometabolism, obesity, T2DM) and its notable delayed skin wound healing. However, a characterization of the temporal cellular dynamics of the db/db wound healing model has not been performed, nor has the model been systematically compared to human DFUs. We performed the first comprehensive single-cell, multi-omic analysis of dermal cells in diabetic (db/db) compared to non-diabetic (ND) mice across three time points ranging from the inflammatory to the delayed proliferative and resolution phases of healing. Single-cell transcriptomics were uniquely linked to their corresponding cells surface protein expressions of cell-specific receptors, including immune cells (CD45) such as neutrophils (CD11b, Ly6G), monocytes/macrophages (CD11b, F4/80, CD11c, Ly6C) and T lymphocytes (CD3, CD4), and dermal cells such as endothelial cells (CD31) and fibroblasts (CD26, CD140a), and showed high concordance between protein cell markers and their gene expressions in major cell types. Differential multi-omic analyses characterized two neutrophil (Tnfaip3+Sod2+Ly6G+, Csf3r+Fos+Ly6G+), three monocyte/macrophage (F4/80highCD11bhigh, Ly6chighCD11bhigh, CD11chighCD11blow) and three fibroblast (Pi16+Dpp4+CD26high, Lrrc15+Tnc+CD140ahigh, Cilp+Mgp+CD26low) subtypes showing dysregulated dynamics across the time course of healing in db/db vs ND mice. Notably, NETotic Tnfaip3+Sod2+Ly6G+ neutrophils and phagocytic F4/80highCD11bhigh macrophage subtypes were drastically up-regulated in diabetic wounds. Differential cell-cell communication analyses revealed striking differences in crosstalk dynamics between fibroblast, macrophage and neutrophil subtypes in the early phase of healing, and ligand-receptor interactome analyses identified CD44 as the hub of dysregulated immune cell interactions in diabetic wounds, implicating cell adhesion, migration and inflammatory pathways, especially those mediated by ICAM1. Inhibition of CD44 using blocking antibodies in primary macrophages from db/db mice and via intradermal injections in db/db mice significantly normalized the early wound immune dysfunction, in part by inhibiting ICAM1 and reversing the excessive neutrophil influx into diabetic wounds. A new integrated dataset of single-cell human chronic wound studies revealed similar CD44-mediated immune cell dysfunctions in diabetic vs non-diabetic foot ulcers, pointing to CD44 as a promising therapeutic target for T2DM-associated chronic wounds.

molecular biology↗

bioRxiv2026

Transcriptional regulators predicted to drive macrophage dysregulation during impaired wound healing in diabetic mice

Dysregulation of Mo/M{varphi} activity is known to contribute to impaired healing in diabetes; however, the mechanisms underlying this dysregulation are not well understood. In this study, we used a variety of bioinformatics approaches along with our time series scRNA-seq data on wound Mo/M{varphi} from non-diabetic and diabetic mice to identify transcriptional regulators (TRs) that drive Mo/M{varphi} state transitions during normal and impaired healing. First, we used the Lamian framework and our newly developed Pseudotime Graph Diffusion method to show that state transitions from early stage phenotypes to later stage reparative and antigen presenting phenotypes characteristic of normally healing wounds are impaired and that transitions to inflammatory, foam cell-like, and Lyve-1+ M{varphi} phenotypes are enhanced during impaired healing of diabetic mice. Using our BITFAM model, we identified a broad range of TRs predicted to be preferentially active in each cell state and using CellOracle, we performed in silico perturbation to identify groups of TRs predicted to drive cell state transitions along multiple trajectories (e.g. CEBPA, IRF8), whereas other TRs were predicted to drive cell state transition towards reparative phenotypes (e.g. NR1H3, NR3C1) or towards an antigen-presenting phenotype (e.g. IRF4, OGT). Selected findings were validated using existing experimental data, confirming the usefulness of this approach. In conclusion, we identified TRs that likely drive Mo/M{varphi} state transitions towards desirable and undesirable phenotypes for wound healing. These findings provide insight into novel targets for altering Mo/M{varphi} phenotypes to promote healing of diabetic wounds.

immunology↗

bioRxiv2026

A Novel Monocyte-derived Antigen Presenting Cell-T regulatory Cell Axis Contributes to Skin Wound healing and is Impaired in Diabetic Mice

Despite a vast literature on the role of macrophages in wound healing, the role of dermal monocyte (Mo)-derived antigen presenting cells (APC) has received scant attention. Using scRNAseq and flow cytometry, we identify a population of APC that is prominent in wounds of non-diabetic mice but is reduced in wounds of diabetic mice. Using adoptive transfer experiments and Ccr2 knockout mice, we demonstrate that wound APC are derived primarily from Mo and that the diabetic wound environment inhibits differentiation of Mo into APC. We also show that Mo-specific Irf4 knockout mice exhibit reduced differentiation of Mo into APC, decreased levels of IL27 and numbers of activated Treg cells in wounds. and impaired wound healing. Importantly, adoptive transfer of bone marrow Mo that express Irf4 into wounds of Mo-specific Irf4 knockout mice rescued levels of wound APC and activated Treg, as well as wound healing. Local administration of recombinant IL27 into wounds of these mice also rescued levels of activated Treg in wounds, along with wound healing, Together, these findings identify a novel pathway in which IRF4 induces Mo differentiation into APC in wounds, which in turn produce IL27 that activates Treg to promote healing. This pathway is impaired in wounds of diabetic mice, which provides a novel target to improve diabetic wound healing.

immunology↗

bioRxiv2026

Pseudotime graph diffusion for post hoc visualization of inferred single-cell trajectories

Visual representations are widely used to interpret trajectories in single-cell data; however, they do not always faithfully capture inferred trajectory structure. As a result, interpretation of cellular dynamics and downstream analyses may be compromised. Here, we present Pseudotime Graph Diffusion (PGD), a lightweight and interpretable post hoc framework for smoothing cell-level features along pseudotime. PGD operates by performing random-walk diffusion on a pseudotime graph, propagating information along inferred trajectory paths to enhance continuity and structure. We demonstrate that PGD-smoothed embeddings improve visualization of increasingly complex inferred trajectories of monocytes and macrophages during wound healing. We further show that PGD extends naturally to trajectory-aware gene expression smoothing and scales to atlas-sized datasets. By improving agreement between visual representations and inferred trajectories, PGD enables more faithful interpretation of dynamic cellular processes.

bioinformatics↗

bioRxiv2023

Diet-induced obesity dysregulates chromatin oxygen sensing regulating efferocytosis in macrophages

Macrophages are plastic cell populations that normally adapt to their environment. Cellular adaptation to hypoxia occurs through transcription factors including hypoxia-inducible factors, and hypoxia-inducible transcriptions are further regulated by chromatin response through histone modification including histone methylation. However, the role of histone methylation in the hypoxia response of macrophages is not well understood. As obesity is associated with dysregulated macrophage functions, we investigated whether hypoxia response is cell-intrinsically dysregulated in macrophages in obesity. In mouse bone marrow-derived macrophages (BMDMs), immunoblotting revealed that 1% hypoxia rapidly increases the global levels of histone 3 methylations. We found that hypoxia-induction of histone 3-lysine 4 tri-methylation (H3K4me3) is specifically inhibited in BMDMs from mice fed a high-fat diet (HFD-BMDMs) compared to BMDMs from mice fed a normal diet (ND-BMDMs). Multi-omics approach with ChIP-seq and RNA-seq identified that glycolysis-related pathways and genes including Aldoa are upregulated after prolonged hypoxia along with upregulated H3K4me3 in ND-BMDMs. In contrast, no pathway is associated with hypoxia-upregulated H3K4me3 peaks in HFD-BMDMs and hypoxia-induced Aldoa expression is decreased in HFD-BMDMs, suggesting both the extent and the genome location of H3K4me3 response to hypoxia is dysregulated in obesity. Consistently, lactate accumulation and induction of histone lactylation under hypoxia are reduced in HFD-BMDMs. Furthermore, HFD-BMDMs exhibited decreased dying cell clearance under hypoxia due to the reduced capacity of anaerobic glycolysis. Competitive bone marrow transplantation of hematopoietic stem cells (HSCs) shows that HFD-induced long-term memory reflects the impaired dying cell clearance in differentiated BMDMs, which is rescued by inhibiting oxidative stress in HSCs. In summary, chromatin response to hypoxia associated with H3K4me3 enrichment governs transcriptions for anaerobic glycolysis and dying cell clearance under hypoxia. Obesity dysregulates the extent and the genome location of H3K4me3 enrichment, glycolysis, and dying cell clearance of BMDMs under hypoxia, which is initiated in HSPCs via oxidative stress.

cell biology↗