Inflammatory and apoptotic remodeling in autonomic nervous system following myocardial infarction

Chronic myocardial infarction (MI) triggers pathological remodeling in the heart and cardiac nervous system. Abnormal function of the autonomic nervous system (ANS), including stellate ganglia (SG) and dorsal root ganglia (DRG) contribute to increased sympathoexcitation, cardiac dysfunction and arrythmogenesis. ANS modulation is a therapeutic target for arrhythmia associated with cardiac injury. However, the molecular mechanism involved in the pathological remodeling in ANS following cardiac injury remains to be established.

In this study, we performed transcriptome analysis by RNA-sequencing in thoracic SG and (T1-T4) DRG obtained from Yorkshire pigs following either acute (3 to 5 hours) or chronic (8 weeks) myocardial infarction. By differential expression and weighted gene co-expression network analysis (WGCNA), we identified significant transcriptome changes and specific gene modules in the ANS tissues in response to myocardial infarction at either acute or chronic phases. Both differential expressed genes and the member genes of the WGCNA gene module associated with post-infarct condition were significantly enriched for inflammatory signaling and apoptotic cell death. Targeted validation analysis supported a significant induction of inflammatory and apoptotic signal in both SG and DRG following myocardial infarction, along with cellular evidence of apoptosis induction based on TUNEL analysis. Importantly, these molecular changes were observed specifically in the thoracic segments but not in their counterparts obtained from lumbar sections.

Myocardial injury leads to time-dependent global changes in gene expression in the innervating ANS. Induction of inflammatory gene expression and loss of neuron cell viability in SG and DRG are potential novel mechanisms contributing to abnormal ANS function which can promote cardiac arrhythmia and pathological remodeling in myocardium.