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Sympathetic Reinnervation Alters the Inflammatory Response Following Myocardial Infarction
Author(s) -
Sepe Joseph,
Gardner Ryan,
Betts Courtney,
Sivagnanam Sam,
Larson Will,
Coussens Lisa,
Habecker Beth
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.04202
Subject(s) - immune system , medicine , inflammation , ischemia , reperfusion injury , cd8 , immunology
Myocardial infarction (MI) triggers an intense inflammatory response that is essential for proper cardiac healing and repair, but can also be deleterious. Recent studies have elucidated that the sympathetic nervous system can regulate the inflammatory response throughout the body. However, it is not known if sympathetic nerves modulate the inflammatory response in the heart after ischemia‐reperfusion injury. We sought to test the hypothesis that restoring sympathetic transmission throughout the left ventricle (LV) by promoting axon regeneration after ischemia‐reperfusion would enhance the cardiac repair process and alter the immune cell types present during scar formation. To study this, we treated mice with Intracellular Sigma Peptide (ISP) or the small molecule HJ‐02 on days 3‐10 after ischemia‐reperfusion injury in order to restore sympathetic innervation throughout the LV. We then applied state of the art quantitative multiplex immunohistochemistry (mIHC) methodology, adapted from cancer studies, to the heart in order to identify the full array of immune cell phenotypes present following MI. We sequentially stained cardiac sections with 23 antibodies and used image cytometry to identify immune cell lineages (macrophages, dendritic cells, CD8 + and CD4 + T cells, B cells, and granulocytes) as well as multiple subpopulations including M1‐like and M2‐like macrophages, and regulatory T cells (Tregs). Using this novel mIHC approach, we demonstrate that macrophages (HJ‐02: 17.3 ± 2.6%; ISP: 15 ± 2.3%; VEH: 9.9 ± 1.5% of CD45 + immune cells) and dendritic cells (HJ‐02: 11.5 ± 1.1%; ISP: 9.3 ± 1.4%; VEH: 5.0 ± 1.3% of CD45 + immune cells) were significantly elevated in the hearts of reinnervated groups, while the presence of other immune cell populations (B cells, CD4 + T cells, CD8 + T cells, and granulocytes) were invariant compared to vehicle control hearts. Reinnervated hearts had significantly elevated levels of M2‐like macrophages (HJ‐02: 70.3 ± 2.4%; ISP: 62.0 ± 3.9%; VEH: 52.7 ± 2.9% of total macrophages) and Tregs (HJ‐02: 34.7 ± 3.6%; ISP: 27.2 ± 3.6%; VEH: 20.3 ± 2.3% of CD4 + T cells) compared to vehicle control animals. Between the reinnervated groups, cardiac tissue from HJ‐02 treated mice contained increased presence of M2‐like macrophages (P < 0.01) and Tregs (P < 0.05) compared to ISP treated animals, and this correlated with decreased infarct size. Collectively, these observations establish that sympathetic reinnervation of the infarcted myocardium alters the inflammatory response. Additionally, this study establishes a new, robust methodological approach (mIHC) to comprehensively study the immune cells present in the heart.