Project description:<p>The role of sebaceous glands (SGs) in the early pathogenesis of hidradenitis suppurativa (HS) is undefined, with unclear causal relationship to inflammatory sequelae. The aim of this study was to determine whether SG aberrations constitute a primary pathogenic driver in early HS and elucidate the underlying mechanism. Histological study, single-cell RNA sequencing (scRNA-seq), and in vitro functional assays were employed. Clinical specimens included non-lesional skin, early lesional skin from patients diagnosed with Hurley I HS, and healthy controls. Human SZ95 sebocytes were used for mechanistic studies, including gene knockdown with lentivirus, bulk RNA sequencing, and liquid chromatography-tandem mass spectrometry based lipidomic analysis. </p><p>The size of SG was significantly reduced in HS patients. Development aberration and significant downregulation of tight junction signaling (e.g., TJP1, OCLN, CLDN1) in HS SGs were revealed by scRNA-seq, associated with compromised barrier integrity and early CD45+ immune cell infiltration. Knockdown of CLDN1 in human SZ95 sebocytes recapitulated these findings, inducing a robust pro-inflammatory response and a shift toward keratinocyte-like lineage accompanied by metabolic reprogramming, specifically overproduction of lysophosphatidylcholine (LPC). Exogenous LPC directly promoted proliferation and inflammatory cytokine secretion in HaCaT keratinocytes. Collectively, these findings reposition SGs as instigators in the early pathogenesis of HS.</p>
Project description:Kilian2024 - Immune cell dynamics in Cue-Induced Extended Human Colitis Model
Single-cell technologies such as scRNA-seq and flow cytometry provide critical insights into immune cell behavior in inflammatory bowel disease (IBD). However, integrating these datasets into computational models for dynamic analysis remains challenging. Here, Kilian et al., (2024) developed a deterministic ODE-based model that incorporates these technologies to study immune cell population changes in murine colitis. The model parameters were optimized to fit experimental data, ensuring an accurate representation of immune cell behavior over time. It was then validated by comparing simulations with experimental data using Pearson’s correlation and further tested on independent datasets to confirm its robustness. Additionally, the model was applied to clinical bulk RNA-seq data from human IBD patients, providing valuable insights into immune system dynamics and potential therapeutic strategies.
Figure 4c, obtained from the simulation of human colitis model is highlighted here.
This model is described in the article:
Kilian, C., Ulrich, H., Zouboulis, V.A. et al. Longitudinal single-cell data informs deterministic modelling of inflammatory bowel disease. npj Syst Biol Appl 10, 69 (2024). https://doi.org/10.1038/s41540-024-00395-9
Abstract:
Single-cell-based methods such as flow cytometry or single-cell mRNA sequencing (scRNA-seq) allow deep molecular and cellular profiling of immunological processes. Despite their high throughput, however, these measurements represent only a snapshot in time. Here, we explore how longitudinal single-cell-based datasets can be used for deterministic ordinary differential equation (ODE)-based modelling to mechanistically describe immune dynamics. We derived longitudinal changes in cell numbers of colonic cell types during inflammatory bowel disease (IBD) from flow cytometry and scRNA-seq data of murine colitis using ODE-based models. Our mathematical model generalised well across different protocols and experimental techniques, and we hypothesised that the estimated model parameters reflect biological processes. We validated this prediction of cellular turnover rates with KI-67 staining and with gene expression information from the scRNA-seq data not used for model fitting. Finally, we tested the translational relevance of the mathematical model by deconvolution of longitudinal bulk mRNA-sequencing data from a cohort of human IBD patients treated with olamkicept. We found that neutrophil depletion may contribute to IBD patients entering remission. The predictive power of IBD deterministic modelling highlights its potential to advance our understanding of immune dynamics in health and disease.
This model was curated during the Hackathon hosted by BioMed X GmbH in 2024.
Project description:Langerhans cells (LCs) in the epidermis promote immune homeostasis, efficiently activating tolerogenic and immunogenic T cell responses. To understand genomic programming in human Langerhans cells we performed whole transcriptome (bulk RNA-seq and single cell RNA-seq) profiling and analysis of H3K4Me3 and H3K27Ac histone modifications across LC genome in primary human cells from 6 independent donors. Primary LCs were either unstimulated and stimulated with TNF-alpha. Additionally we performed a CRISPR editing experiment for IRF4
Project description:This model was reconstructed from single-nucleus RNA-seq (snRNA-seq) data of human postmortem brain and curated using published metabolomics data from human iPSC-derived neurons and cerebrospinal fluid (CSF), together with gene expression data from the Human Protein Atlas. It more accurately simulates human neuronal metabolic flux in neurodegenerative conditions such as Alzheimer's disease (AD).
Project description:The cytoskeletal mechanisms regulating inflammatory responses in the epidermis are not well described. Here we addressed this question by inducing a psoriatic phenotype in human keratinocytes and reconstructed human epidermis using a cytokine stimulation model.We report the results from RNA-seq in N/TERT keratinocytes treated with M5 or both M5 and ROCK2 inhibitor KD025.
Project description:Mice with deficient expression of RASSF9 exhibit intriguing phenotypes of skin-related pathology, including abnormal thickening of the epidermis, dysregulated proliferation of keratinocytes, and alopecia. To delineate the underlying mechanism, we profiled gene expression in keratinocytes of RASSF9-mutant mice to identify targets whose expressions were affected by RASSF9 gene deletion. Primary keratinocytes from neonatal ICR mice of wildtype control (WT) or homozygous RASSF9 deletion (RASSF9-/-) were harvested for RNA extraction and hybridization on Affymetrix microarrays. For WT, a single microarray hybridization was performed. For RASSF9-/-, one hybridization was performed for each of two independent samples.
Project description:Skin is usually exposed during human exposures to ionizing radiation, however there are few experiments that evaluate the radiation responsiveness of the cells of the epidermis (keratinocytes) and those of the dermis (fibroblasts) in the same studies. We evaluated the transcriptional responses of quiesent primary keratinocytes and fibroblasts from the same individual and compared them with quiescent keratinocytes and fibroblasts that were immortalized by human telomerase (hTert). The primary transcriptional responses to 10-500 cGy ionizing radiation were p53-mediated responses; however, we did identify distinct responses between the keratinocytes and the fibroblasts. Experiment Overall Design: Four cell types (primary keratinocytes, hTert immortalized keratinocytes, primary fibroblasts, hTert immortalized fibroblasts) grown to quiescence, treated with 0, 10, 100 or 500 cGy gamma irradiation, RNA collected at 4 hrs.
Project description:IL-20 cytokines are involved in the establishment of psoriasis, a common chronic skin inflammation epidemiologically associated with metabolic syndrome, but molecular mechanisms underlying their over-expression remain to be elucidated. We find that keratinocytes (KCs) expressed IL-20 and lymphocytes expressed IL-22 cytokines up-regulation occurs at post-transcriptional level with stabilization of their RNA messengers. Looking at psoriatic epidermis, we observe that the p38/MK2 pathway is not activated but that the RNA-binding protein (RBP) HuR re-localizes in keratinocytes cytoplasm, suggesting post-transcriptional regulation of numerous mRNAs. HuR ribonucleoprotein immunoprecipitations analyzed by high-throughput sequencing (RIP-Seq) identify potential pre-mature and mature RNA targets for uninvolved and involved skin and confirms that HuR activity is displaced from the nucleus to the cytoplasm. Numerous psoriasis up-regulated transcripts are HuR targets and HuR knockdown reduces expression of transcripts like beta-defensin-2, CXCL-10 or IL-2, suggesting an implication of HuR in pathophysiological processes such as morphological, immune and metabolic inflammatory responses. Finally, metabolic disorders affecting psoriatic keratinocytes are responsible for HuR cytoplasmic localization since a decreased activity of the cellular metabolic sensor AMPK, that is observed in human psoriatic epidermis, is sufficient to promote HuR cytosolic localization as well as IL-20 over-production both in human keratinocytes and in vivo in mouse epidermis where it then initiates psoriasis-like histological changes. These results may provide insights into molecular links between metabolism and post-transcriptional networks during chronic inflammation, as illustrated in psoriasis by mechanisms connecting AMPK, HuR and IL-20. Analysis of HuR-binding RNA in uninvolved versus involved psoriatic samples by RIP-Seq. Samples from five different patients were used for both uninvolved and involved skin. RIP-Seq was also made using a control IgG.
Project description:Skin is usually exposed during human exposures to ionizing radiation, however there are few experiments that evaluate the radiation responsiveness of the cells of the epidermis (keratinocytes) and those of the dermis (fibroblasts) in the same studies. We evaluated the transcriptional responses of quiesent primary keratinocytes and fibroblasts from the same individual and compared them with quiescent keratinocytes and fibroblasts that were immortalized by human telomerase (hTert). The primary transcriptional responses to 10-500 cGy ionizing radiation were p53-mediated responses; however, we did identify distinct responses between the keratinocytes and the fibroblasts. Keywords: keratinocytes and fibroblasts - dose response to ionizing radiation