Abstract The prevalence of cardiac dysfunction and its vast implications for human health highlight the need to investigate the mechanistic processes allowing its pathological manifestations. Studies from our lab revealed Pseudomonas aeruginosa (P.a.) infection causes severe cardiac inflammation and dysfunction, despite absence of the bacteria in the heart. However, the underlying mechanism is unknown. Thus, we hypothesize cardiac fibroblast activation by PAMPs enhances cytokine and chemokine release, driving cardiac inflammation. To test our hypothesis in vitro, we used human monocyte derived macrophages (hMDMs) and cardiac fibroblasts (HCFs). We harvested conditioned media (CM) from P.a. infected hMDMs and exposed to HCFs. RNA was extracted at different time points, next generation mRNA sequencing was performed and supernatants were harvested to determine inflammatory cytokine. Our data revealed exposing CM to HCFs upregulates cytokine and chemokine gene expression. Also, we found CCL2, TNF-α and IL-1β levels are high in supernatants harvested from HCFs. To further investigate mechanisms controlling CCL2 expression in HCFs, we identified JNK was involved in induction of CCL2 in HCF. In conclusion, activation of HCFs releases chemokines (CCL2) which recruit leukocytes into heart tissue, causing severe cardiac inflammation. Ongoing and future studies are needed to dive further into mechanisms of this pathway, showing its potential impact in driving cardiac inflammation in vivo.
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