Biology subjects

Ha, M. K.

Publications and source records attributed to Ha, M. K..

5 recordsLinked to original sources

bioRxiv2026

Longitudinal Profiling of CD4⁺ T Cell Responses Following de novo Yellow Fever Vaccination

The yellow fever 17D vaccine is one of the most successful live-attenuated viral vaccines, yet the cellular mechanisms underlying its long-term protection remain not fully understood. This study provides a longitudinal analysis of the human CD4+ T cell and IgG response following de novo yellow fever vaccination by focusing. Peripheral blood mononuclear cells (PBMCs) from 49 vaccinated individuals were stimulated with yellow fever (YF) and control peptide pools across four timepoints: pre-vaccination/baseline (D1), day 22 (D22), day 43 (D43), and one year (D365) post-vaccination. Activation-induced marker (AIM) assays confirmed robust activation of CD4+ T cells following yellow fever peptide stimulation, peaking at day 22 post-vaccination and subsequently declining. T-cell receptor (TCR{beta}) sequencing of AIM-sorted CD4+ T cells showed a transient increase in clonal diversity at D22, consistent with broad epitope targeting and early polyclonal expansion. This was followed by repertoire contraction, which could indicate the persistence of a limited set of dominant clonotypes responsible for immune memory formation. TCR repertoires remained largely private over time, indicating a mostly individualized immune response. Next, serological analyses revealed a robust and highly yellow fever virus (YFV)-specific IgG response. Antibody levels peaked within the D22-D43 window and remained elevated at one year post-vaccination. Cross-reactivity toward other flaviviruses was limited, suggesting an antigen-specific humoral response. Together, these findings characterize the longitudinal dynamics of the CD4+ T cell and IgG response following de novo yellow fever vaccination and provide insights into the mechanisms contributing to durable antiviral immunity.

immunology↗

bioRxiv2026

The T cell receptor repertoire captures healthy aging and CMV independently from epigenetic clocks

Human aging is the process through which numerous biological changes occur during life, affecting various processes. In some elderly individuals, this functional decline becomes more pronounced, leading to frailty, a condition characterised by reduced physiological reserves and increased vulnerability to stress. With the global rise of life expectancy, identification of biomarkers for healthspan and frailty are becoming more important. In this study, we directly compare two molecular readouts, namely the T cell receptor (TCR) repertoire and epigenetic clocks, on their ability to discern healthy aging. On blood samples from sixteen individuals, across age-matched healthy elderly and frail individuals, both TCR sequencing and epigenetic profiling were performed. A significantly higher TCR repertoire diversity in the CD4+ T cells differentiated the healthy elderly individuals from the frailty ones. Epigenetic clock signatures of biological relative to chronological ageing rate, did not show a clear difference between both groups. However, when taking into account the CMV-serostatus, a significant increase in epigenetic aging could be observed in the CMV-seropositive individuals. Our results support a clear hypothesis on the role of CMV infection in the healthy aging of the immune system. In healthy elderly, CMV is typically controlled by CD4+ T cells, however, in the frail elderly, the burden of managing the infection shifts to the CD8+ T cells. This change is marked by two key changes: a decrease in TCR diversity for seropositive individuals compared to seronegative individuals, as well as an increase in the fraction of CMV-associated TCRs within the CD8+ T cells. These findings contribute to our understanding of aging and provide insight into how CMV-infection may affect healthy aging and frailty. They also underline the crucial role of the immune system in healthy aging and the value of further investigating ageing-related health/disease patterns in the TCR repertoire to determine healthspan/lifespan.

immunology↗

bioRxiv2025

T cell-microbiome associations captured through T cell receptor convergence analysis

The gut microbiome modulates mucosal immunity, yet how specific bacterial taxa shape the diversity and specificity of T cell receptor (TCR) repertoires remains poorly understood. Existing approaches emphasize single-species effects or broad immune features, without pinpointing which microbes drive specific T cell clonotypes. We present AIRRWAS, a computational framework that integrates TCR-microbiome interaction analysis with targeted in vitro validation to detect genus-level TCR convergence. Applied to three independent cohorts, AIRRWAS identified reproducible associations between convergent TCR clusters and 21 bacterial genera spanning core commensals, probiotics and taxa with immunomodulatory roles. Predicted clonotypes were enriched within the TCR-microbiome interaction network and preferentially activated by genus-matched stimuli, eliciting different functional T cell responses. These findings demonstrate that distinct repertoires can share genus-specific TCR motifs, enabling detection of shared immune signatures. AIRRWAS can map these TCR- microbiome interactions, laying the groundwork for biomarker discovery immune monitoring and the development of microbiome-targeted therapies.

bioinformatics↗

bioRxiv2025

Generation of a T cell receptor, cytokine and cell repertoire synovial fluid atlas to define commonalities and dissimilarities between arthritic diseases through systems immunology approaches

Although different chronic arthritic diseases are defined by clinical factors like gender, psoriasis and auto-antibodies, the biology of inflamed joints while comparing the different diseases remains neglected. Here, after curating an inflamed joint derived T-cell receptor (TCR) database, our new TRIASSIC tool identified 66303 significantly convergent TCR clonotypes. Clustering TCR clonotypes showed that synovial fluid convergence clusters (SFCCs) characterized HLA-B27+ mediated diseases (spondyloarthritis, SpA, and enthesitis-related juvenile idiopathic arthritis, JIA-ERA), Lyme arthritis and oligoarticular JIA. Single-cell transcriptomics and bulk proteomics showed upregulated interferon type I and II and TNF- pathways in oJIA. Adult and juvenile psoriatic arthritis, (JIA-)PsA, was characterized by upregulated HSP expression in monocytes and TXNIP in T-cells. We discovered an abundance of CCL5 expressing CD8+ T-cells in SF from HLA-B27+ JIA-ERA and SpA patients. JIA-ERA patients showed upregulation of CD74 and LGALS1 in Th1 and Th17 cells and IGHV7-4.1 in B-cells. oJIA patients shared a TRBV28 RG-motif on CXCL13 producing helper T-cells. Rheumatoid arthritis and (JIA-)PsA patients carried EBV-reactive cytotoxic CD8+ T-cells. Annexin signalling was shown to be important in the intercellular communication for all arthritis groups. Collectively, our work showed that chronic arthritis is characterized by both disease-specific and broadly shared mechanisms.

immunology↗

bioRxiv2019

Mass Cytometry Study on the Heterogeneity in Cellular Association and Cytotoxicity of Silver Nanoparticles in Human Immune Cells

There have been many reports about the adverse effects of nanoparticles (NPs) on the environment and human health. Conventional toxicity assessments of NPs frequently assume uniform distribution of monodisperse NPs in homogeneous cell populations, and provide information on the relationships between the administered dose of NPs and cellular responses averaged for a large number of cells. They may have limitations in describing the wide heterogeneity of cell-NP interactions, caused by cell-to-cell and NP-to-NP variances. To achieve more detailed insight into the heterogeneity of cell-NP interactions, it is essential to understand the cellular association and adverse effects of NPs at single-cell level. In this study, we applied mass cytometry to investigate the interactions between silver nanoparticles (AgNPs) and primary human immune cells. High dimensionality of mass cytometry allowed us to identify various immune cell types and observe the cellular association and toxicity of AgNPs in each population. Our findings showed that AgNPs had higher affinity with phagocytic cells like monocytes and dendritic cells and caused more severe toxic effects than with T cells, B cells and NK cells. Multi-element detection capability of mass cytometry also enabled us to simultaneously monitor cellular AgNP dose and intracellular signaling of individual cells, and subsequently investigate the dose-response relationships of each immune population at single-cell level, which are often hidden in conventional toxicity assays at bulk-cell level. Our study will assist future development of single-cell dose-response models for various NPs and will provide key information for the safe use of nanomaterials for biomedical applications.

biochemistry↗