Biology subjects

Roumelioti, F.

Publications and source records attributed to Roumelioti, F..

4 recordsLinked to original sources

bioRxiv2023

Cellular complexity and crosstalk in murine TNF-dependent ileitis: Different fibroblast subsets propel spatially defined ileal inflammation through TNFR1 signalling

Crohns disease represents a persistent inflammatory disorder primarily affecting the terminal ileum. Through the application of single-cell RNA sequencing, we unveil the intricate cellular complexities within murine TNF-dependent ileitis, developing in Tnf{Delta}ARE mice. Detailed immune cell analysis highlights B cell expansion, T cell effector reprogramming, and macrophage lineage shifts during inflammation. Focusing on stromal cells, we reveal a strong pro-inflammatory character, acquired by all fibroblast subsets, which exhibit complex communication patterns with the infiltrating immune and surrounding stromal cells. Interestingly, we identify that Tnf{Delta}ARE-induced ileitis is initiated in the lamina propria via TNFR1 pathway activation in villus-associated fibroblasts (Telocytes and Pdgfralow cells). Furthermore, we unveil separate spatial subsets of fibroblasts acting as exclusive responders to TNF, each orchestrating inflammation in different intestinal layers. Additionally, manipulating the Tnfrsf1a gene exclusively in fibroblast subsets suggests that inflammation is initiated by telocytes and Pdgfralow cells, while trophocytes drive its progression. This introduces novel evidence of spatial regulation of inflammation by fibroblast subsets, inciting and advancing disease in different layers of the gut. These findings underscore the pivotal role of fibroblasts in the inception and advancement of ileitis, proposing that targeting different fibroblast populations could impede the disease development and chronicity of inflammation.

cell biology↗

bioRxiv2022

Repurposing of Amisulpride, a known antipsychotic drug, to target synovial fibroblasts activation in arthritis.

Synovial Fibroblasts (SFs) are key pathogenic drivers in arthritis and their in vivo activation by TNF is sufficient to orchestrate full arthritic pathogenesis in animal models. TNF blockade has been efficacious for a large percentage of Rheumatoid Arthritis (RA) patients, although characterized by a plethora of side effects. Novel therapeutic discoveries remain however challenging, especially in optimizing drug safety, side effects, longer-term responses, costs and administration routes. Aiming to find new potent therapeutics, we applied the L1000CDS2 search engine, in order to identify compounds that could potentially reverse the pathogenic expression signature of arthritogenic SFs, derived from the human TNF transgenic mouse model (hTNFtg). We identified a neuroleptic drug, namely Amisulpride, which was validated to reduce SFs inflammatory potential while decreasing the clinical score of hTNFtg polyarthritis. Notably, we found that Amisulpride did not exert its biological activities through its known targets Dopamine receptors 2 and 3 and Serotonin Receptor 7, nor through TNF-TNFRI binding inhibition. By applying a click chemistry approach, novel potential targets of Amisulpride were identified, which were further validated to repress hTNFtg SFs inflammatory potential in vitro (Ascc3 and Sec62), while phosphoproteomics analysis revealed important fibroblast activation pathways, such as adhesion, to be altered upon treatment. Our data support that Amisulpride could provide an additive beneficial effect to patients suffering from RA and comorbid dysthymia, as it may reduce SFs pathogenicity in parallel with its anti-depressive activity. Importantly, Amisulpride may also serve as a "lead" compound for the development of novel, more potent therapeutics against chronic inflammatory diseases.

pharmacology and toxicology↗

bioRxiv2022

miR-221/222 drive synovial fibroblast expansion and pathogenesis of TNF-mediated arthritis

MicroRNAs (miRNAs) constitute fine tuners of gene expression and are implicated in a variety of diseases spanning from inflammation to cancer. miRNA expression is deregulated in rheumatoid arthritis (RA), however, their specific role in key arthritogenic cells such as the synovial fibroblast (SF) remains elusive. We have shown in the past that the expression of the miR-221/222 cluster is upregulated in RA SFs. Here, we demonstrate that miR-221/222 activation is downstream of major inflammatory cytokines, such as TNF and IL-1{beta}, which promote miR-221/222 expression independently. miR-221/222 expression in SFs from the huTNFtg mouse model of arthritis correlates with disease progression. Targeted transgenic overexpression of miR-221/222 in SFs of the huTNFtg mouse model led to further expansion of synovial fibroblasts and disease exacerbation. miR-221/222 overexpression altered the transcriptional profile of SFs igniting pathways involved in cell cycle progression and ECM regulation. Validated targets of miR-221/222 included p27 and p57 cell cycle inhibitors, as well as Smarca1 (a chromatin remodeling component). In contrast, complete genetic ablation of miR-221/222 in arthritic mice led to decreased proliferation of fibroblasts, reduced synovial expansion and attenuated disease. scATAC-seq data analysis revealed increased miR-221/222 gene activity in the pathogenic and activated clusters of the intermediate and lining compartment. Taken together, our results establish an SF-specific pathogenic role of the miR-221/222 cluster in arthritis and suggest that its therapeutic targeting in specific subpopulations should inform the design of novel fibroblast-targeted therapies for human disease.

cell biology↗

bioRxiv2019

Dual airway and alveolar contributions to adult lung homeostasis and carcinogenesis

Lung adenocarcinoma (LUAD) and chronic lung diseases caused by smoking and environmental noxious agents are the deadliest diseases worldwide, sharing a partially charted pathobiology of dysfunctional alveolar repair. Here we sought to identify the respiratory epithelial dynamics and molecular signatures participating in adult lung maintenance and chemical carcinogenesis. We employed novel mouse models of respiratory epithelial marking and ablation, a battery of pulmonary toxins and carcinogens, experimental protocols of carcinogen-induced LUAD, tobacco carcinogen-induced LUAD cell lines, and human transcriptomic data and identified a prominent involvement of airway molecular programs in alveolar maintenance and carcinogen-induced LUAD. The airway-specific transcriptomic signature was redistributed to the alveoli after toxic and carcinogenic insults and resulted in marked contributions of airway-labeled cells to injury-recovered alveoli and LUAD. Airway cells maintained Kras mutations and therefore possibly contributed to lung cancer initiation, while LUAD were spatially linked to neighboring airways. Transcriptomic profiling of carcinogen-induced murine and human LUAD revealed enrichment in airway signatures, while ablation of airway cells distorted alveolar structure and function and protected mice from LUAD development. Collectively, these results indicate that airway cells and/or transcriptomic signatures are essential for alveolar maintenance and LUAD development.

cancer biology↗