Biology subjects

Asalla, S.

Publications and source records attributed to Asalla, S..

2 recordsLinked to original sources

bioRxiv2026

Extracellular Vesicles Mediate Activation and Trafficking of Splenic Immune Cells to the Heart Post-Myocardial Infarction

BackgroundMyocardial infarction (MI) triggers splenic immune cell trafficking to the heart. Vehicles that carry these signals and mediate this crosstalk are unknown. HypothesisWe hypothesize that extracellular vesicles (EVs) released post-MI mediate splenic immune trafficking to the heart. MethodsMice were treated daily with an EV biogenesis inhibitor (GW4869) or vehicle. Splenic/cardiac immune cells were assessed at 3d while survival, cardiac function, hypertrophy, and fibrosis were evaluated at 8w post-MI. Plasma EVs from 1d MI mice or from the hearts that underwent MI/sham in a Langendorff system induced splenic immune trafficking to the heart within 3d and systolic dysfunction at 8w in naive mice. ResultsGW4869 i) inhibited splenic regression, ii) increased splenic retention of neutrophils, monocytes, dendritic cells (DCs), and CD4 T-cells, iii) decreased cardiac gene expression of pro-inflammatory cytokines/chemokines, and iv) decreased trafficking of immune cells to the hearts at 3d post-MI, and iii) improved systolic function and attenuated hypertrophy at 8w post-MI. MI EVs accumulated in the spleen and promoted egress of matured splenic immune cells upon administration to naive mice. Cardiac pro-inflammatory cytokines/chemokines expression and CCR2+MHC-IIhi infiltrating macrophages, CD11c+ DCs, and CD4+ and CD4+TNF+ T-cell levels were also increased in naive mice at 3d post-injection. Importantly, transfer of MI EVs for 2 days induced systolic dysfunction, cellular hypertrophy, and fibrosis in naive mice at 8 w post-injection. DCs process MI EVs for T-cells activation. ConclusionsEVs mobilize splenic immune cells to the heart post-MI and their inhibition can subdue inflammatory tissue-damage to promote healing post-MI.

immunology↗

bioRxiv2024

Conditional deletion of CEACAM1 causes hepatic stellate cell activation

ObjectivesHepatic CEACAM1 expression declines with advanced hepatic fibrosis stage in patients with MASH. Global and hepatocyte-specific deletions of Ceacam1 impair insulin clearance to cause hepatic insulin resistance and steatosis. They also cause hepatic inflammation and fibrosis, a condition characterized by excessive collagen production from activated hepatic stellate cells (HSCs). Given the positive effect of PPAR{gamma} on CEACAM1 transcriptoin and on HSCs quiescence, the current studies investigated whether CEACAM1 loss from HSCs causes their activation. MethodsWe examined whether lentiviral shRNA-mediated CEACAM1 donwregulation (KD-LX2) activates cultured human LX2 stellate cells. We also generated LratCre+Cc1fl/fl mutants with conditional Ceacam1 deletion in HSCs and characterized their MASH phenotype. Media transfer experiments were employed to examine whether media from mutant human and murine HSCs activate their wild-type counterparts. ResultsLratCre+Cc1fl/fl mutants displayed hepatic inflammation and fibrosis but without insulin resistance or hepatic steatosis. Their HSCs, like KD-LX2 cells, underwent myofibroblastic transformation and their media activated wild-type HDCs. This was inhibited by nicotinic acid treatment which stemmed the release of IL-6 and fatty acids, both of which activate the epidermal growth factor receptor (EGFR) tyrosine kinase. Gefitinib inhibition of EGFR and its downstream NF-{kappa}B/IL-6/STAT3 inflammatory and MAPK-proliferation pathways also blunted HSCs activation in the absence of CEACAM1. ConclusionsLoss of CEACAM1 in HSCs provoked their myofibroblastic transformation in the absence of insulin resistance and hepatic steatosis. This response is mediated by autocrine HSCs activation of the EGFR pathway that amplifies inflammation and proliferation.

physiology↗