Biology subjects

Gudjonsson, J.

Publications and source records attributed to Gudjonsson, J..

6 recordsLinked to original sources

bioRxiv2026

Fibroblast-encoded inflammatory memory orchestrates recurrent skin inflammation via NNMT-dependent metabolic remodeling

Chronic skin inflammation frequently recurs at the same anatomical sites after therapy withdrawal, implying stromal cells may encode local inflammatory memory. Here, we identified nicotinamide N-methyltransferase (NNMT) as a central metabolic-epigenetic regulator of fibroblast inflammatory memory enabling psoriasis relapse. Single-cell and spatial transcriptomics revealed that dermal fibroblasts acquire a persistent senescence-associated secretory phenotype (SASP) during inflammation, maintaining pro-inflammatory niche in resolved skin that supports CD 8+CD 103+ tissue-resident memory T cell (Trm) differentiation. Multi-omics profiling demonstrated that NNMT depletes S-adenosylmethionine (SAM), reduces H 3K 27me3 deposition, and permits sustained AP-1 occupancy at SASP gene promoters. Fibroblast-specific NNMT ablation or pharmacologic inhibition suppressed SASP activity, limited Trm accumulation, and prevented both initiation and relapse of skin inflammation in mice. These findings establish NNMT as a stromal regulator linking fibroblast metabolism to durable epigenetic memory and propose its targeting to erase inflammatory memory and achieve long-term remission in psoriasis and related immune-mediated diseases. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/721223v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@34b2f4org.highwire.dtl.DTLVardef@1d0bb89org.highwire.dtl.DTLVardef@c8277borg.highwire.dtl.DTLVardef@9825ac_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphic Abstract:C_FLOATNO Proposed mechanism through which NNMT-driven fibroblast SASP facilitates the initiation and recurrence of psoriasis C_FIG

immunology↗

bioRxiv2026

Restoration of Keratinocyte Homeostasis Drives Resolution of Skin Inflammation

Chronic skin inflammation is sustained by reciprocal interactions between epidermal dysfunction and immune activation, yet whether epithelial state actively governs restoration of tissue homeostasis remains unclear. Using a murine model of inflammatory skin disease, we modulated epidermal lipid metabolism and examined its effects on tissue organization. Transcriptomic profiling revealed coordinated reversal of inflammatory, metabolic, and structural gene programs accompanied by normalization of epidermal architecture. Single-cell RNA sequencing showed that this remodeling was concentrated in differentiated keratinocytes, with suppression of IL-17 and neutrophil-associated responses and restoration of barrier and mitochondrial-lipid programs, while stromal and myeloid compartments displayed secondary adaptation. Cross-species analysis demonstrated that resolution-associated gene networks are inversely regulated in human psoriasis. Integrated proteomic and transcriptomic analyses further identified a conserved epithelial regulatory triad whose concordant regulation in psoriasis and atopic dermatitis, and whose in vivo silencing, establish mechanistic control of disease severity. Together, these findings indicate that inflammatory resolution reflects reorganization of epidermal transcriptional networks and position epithelial state as a determinant of inflammatory persistence.

cell biology↗

bioRxiv2025

Insulin-Regulated Actin Dynamics is Disrupted in a Human Keratinocyte Model of Hailey Hailey Disease

Hailey Hailey Disease (HHD) is an autosomal dominant cutaneous disorder caused by mutations in ATP2C1, the gene encoding the Golgi/secretory pathway Ca2+-ATPase SPCA1. Characterized by suprabasal acantholysis and intertriginous blistering of the skin, HHD treatment focuses on managing symptoms as there is no cure. Challenges to targeted therapy are due to the lack of facile and reliable models, both human and rodent, for mechanistic studies. Here we validate and characterize CRISPR/Cas9 mediated single and bi-allelic ATP2C1 knockouts in immortalized human hTERT keratinocytes. Whereas SPCA1 expression, Golgi morphology and Golgi Ca2+ accumulation were proportionately affected in heterozygous and homozygous ATP2C1 null mutants as expected, both single and double allelic mutants showed near complete loss of cadherins associated with desmosomal and adherens junctions. HHD is characterized by poor wound healing and impaired keratinocyte migration. We show that SPCA1 is required for dynamic reorganization of actin cytoskeleton in keratinocyte spreading. We identified an insulin activated PI3K-AKT-Rac1 signaling pathway required for lamellipodia formation and keratinocyte spreading, defective in SPCA1 mutants. Transgenic expression of hSPCA1 or treatment with CDN1163, a small molecule Ca2+-ATPase agonist, restored defective phenotypes in the HHD model, paving the way for future therapeutic approaches to treat this disorder.

cell biology↗

bioRxiv2025

Cross-disease comparison of dermatomyositis and lupus skin identifies inflammatory monocytes and JAK-1 signaling as drivers of vasculopathy in dermatomyositis

Dermatomyositis (DM) is a rare yet devastating autoimmune disease characterized by inflammatory and vasculopathic changes in skin and muscle. DM and systemic lupus erythematosus (lupus) skin lesions have overlapping clinical and histopathological features, yet disparate responses to available therapeutics. DM skin disease is often relapsing and recalcitrant. To investigate DM immunopathogenesis, non-lesional skin, lesional skin, and circulating immune cells from DM patients were analyzed using single-cell RNA-sequencing. Samples were analyzed in parallel with lesional and non-lesional lupus skin, healthy control skin, and peripheral blood. We demonstrate a pervasive type I interferon (IFN) signature in DM stroma that persists in culture and is distinguished from lupus by upregulation of VEGF and IL-18 signaling in DM keratinocytes. Furthermore, endothelial cells (ECs) in lesional DM exhibit decreased proliferation that was not observed in lupus. Using cell communication networks, we identified a population of DM-specific monocytes interacting with non-proliferating DM ECs. Co-culture of monocytes from DM patients with ECs resulted in increased EC apoptosis inhibited by JAK1 blockade. JAK1 inhibition also resulted in reversal of DM-stromal and inflammatory signatures. Together, our data provide a comprehensive cross-disease characterization of lesional and non-lesional skin of DM compared to lupus and implicate monocyte-mediated EC dysfunction in DM vasculopathy and support JAK inhibition for refractory skin disease.

immunology↗

bioRxiv2025

TWEAK Signaling Drives the Transition from Psoriasis to Atopic Dermatitis-like Inflammation in Paradoxical Skin Reactions

Targeted biologics have significantly advanced the treatment of inflammatory skin diseases such as psoriasis; however, some patients paradoxically develop eczematous skin reactions during or after anti-TNF, IL-17, or IL-23 therapy. Although these paradoxical reactions resemble atopic dermatitis clinically and histologically, the molecular mechanisms that drive their development are not fully understood. Here, we generated high-resolution cellular and spatial maps of healthy skin, psoriasis, atopic dermatitis, and paradoxical reactions using single-cell RNA sequencing, spatial transcriptomics, immunohistochemistry, and in vitro assays. In paradoxical reactions, we identified a distinct transcriptional landscape characterized by myeloid and T-cell expansion and an altered keratinocyte phenotype shaped by TWEAK signaling. Mechanistically, we showed that TWEAK synergizes with IL-13 to drive the Th2/type I interferon-polarized epithelial program. Notably, anti-TNF therapy induced TWEAK gene expression in myeloid cells, suggesting a compensatory inflammatory circuit. Together, these findings identify the TWEAK-IL-13 axis as a central driver of paradoxical skin reactions and provide a mechanistic framework for how cytokine blockade may rewire cutaneous immune responses. One Sentence Summary The TWEAK-IL-13 signaling axis is a key driver of immune reprogramming underlying paradoxical skin reactions.

immunology↗

bioRxiv2024

A single cell and spatial genomics atlas of human skin fibroblasts in health and disease

Fibroblasts are critical cells that shape the architecture and cellular ecosystems in multiple tissues. Understanding fibroblast heterogeneity and their spatial context in health and disease has enormous clinical relevance. In this study, we constructed a spatially-resolved atlas of human skin fibroblasts from healthy skin and 23 skin disorders. We define 6 major skin fibroblast populations in health and a further three skin disease-specific fibroblast subtypes, and demonstrate the fibroblast composition in different types of skin disease. We characterise a human-specific fibroblastic reticular cell (FRC)-like subtype in the skin perivascular niche and postulate their origin from prenatal skin lymphoid tissue organiser (LTo)-like cells. We also show that inflammatory myofibroblasts (IL11+MMP1+CXCL5+IL7R+) are a conserved fibroblast subtype in inflammatory disorders and cancers across multiple human tissues. We provide a harmonised nomenclature for skin fibroblasts that integrates previous findings from human skin and other tissues.

cell biology↗