Slit2 Protects Hearts Against Ischemia-Reperfusion Injury by Inhibiting Inflammatory Responses and Maintaining Myofilament Contractile Properties

Xiang Li; Shuang Zheng; Weijiang Tan; Hongqi Chen; Xiaohui Li; Jian Wu; Ting Luo; Xuecong Ren; W Glen Pyle; Lijing Wang; Peter H Backx; Ren Huang; Feng Hua Yang

doi:10.3389/fphys.2020.00228

Slit2 Protects Hearts Against Ischemia-Reperfusion Injury by Inhibiting Inflammatory Responses and Maintaining Myofilament Contractile Properties

Front Physiol. 2020 Mar 27:11:228. doi: 10.3389/fphys.2020.00228. eCollection 2020.

Authors

Xiang Li¹, Shuang Zheng^{1

2}, Weijiang Tan¹, Hongqi Chen¹, Xiaohui Li³, Jian Wu⁴, Ting Luo¹, Xuecong Ren¹, W Glen Pyle⁵, Lijing Wang², Peter H Backx^{6

7}, Ren Huang¹, Feng Hua Yang^{1

3}

Affiliations

¹ Guangdong Province Key Laboratory of Laboratory Animals, Cardiovascular Model Research Center, Guangdong Laboratory Animals Monitoring Institute, Guangzhou, China.
² School of Basic Medicine, Vascular Biology Institute, Guangdong Pharmaceutical University, Guanghzou, China.
³ Department of Cardiovascular Surgery, The First Affiliated Hospital, Jinan University, Guangzhou, China.
⁴ Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital and Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
⁵ Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada.
⁶ Department of Biology, York University, Toronto, ON, Canada.
⁷ Division of Cardiology and the Peter Munk Cardiac Centre, University Health Network, Toronto, ON, Canada.

Abstract

Background: The secreted glycoprotein Slit2, previously known as an axon guidance cue, has recently been found to protect tissues in pathological conditions; however, it is unknown whether Slit2 functions in cardiac ischemia-reperfusion (IR) injury.

Methods: Langendorff-perfused isolated hearts from Slit2-overexpressing (Slit2-Tg) mice and C57BL/6J mice (background strain) were subjected to 20 min of global ischemia followed by 40 min of reperfusion. We compared Slit2-Tg with C57BL/6J mice in terms of left ventricular function and infarct size of post-IR hearts along with tissue histological and biochemical assessments (mRNA and protein expression, phosphorylation status, and myofilament contractile properties).

Results: Slit2 played cardioprotective roles in maintaining contractile function and reducing infarct size in post-IR hearts. IR increased the expression of the Slit2 receptor Robo4 and the membrane receptor Slamf7, but these increases were suppressed by Slit2 overexpression post IR. This suppression was associated with inhibition of the nuclear translocation of NFκB p65 and reductions in IL-1β and IL-18 release into perfusates. Furthermore, Slit2 overexpression attenuated the increases in myofilament-associated PKCs and phosphorylation of cTnI at Ser43 in the post-IR myocardium. The myofilament calcium sensitivity and actomyosin MgATPase activity were preserved in the post-IR Slit2 myocardium.

Conclusion: Our work demonstrates that Slit2 inhibits inflammatory responses and maintains myofilament contractile properties, thus contributing, at least in part, to the prevention of structural and functional damage during IR.

Keywords: RNA sequencing; Slit2; cTnI; contractile function; inflammatory response; ischemia-reperfusion injury; myofilament phosphorylation; protein kinase C.