Inflammatory lung injury is associated with endothelial cell mitochondrial fission and requires the nitration of RhoA and cytoskeletal remodeling

Marissa D Pokharel; Panfeng Fu; Alejandro Garcia-Flores; Manivannan Yegambaram; Qing Lu; Xutong Sun; Hoshang Unwalla; Saurabh Aggarwal; Jeffrey R Fineman; Ting Wang; Stephen M Black

doi:10.1016/j.freeradbiomed.2024.05.019

Inflammatory lung injury is associated with endothelial cell mitochondrial fission and requires the nitration of RhoA and cytoskeletal remodeling

Free Radic Biol Med. 2024 May 10:221:125-135. doi: 10.1016/j.freeradbiomed.2024.05.019. Online ahead of print.

Authors

Affiliations

¹ Department of Cellular & Molecular Medicine, Herbert Wertheim College of Medicine, Miami, FL, USA; Center for Translational Science, Florida International University, Port St. Lucie, FL, USA.
² Center for Translational Science, Florida International University, Port St. Lucie, FL, USA; Department of Environmental Health Sciences, Robert Stempel College of Public Health and Social Work, University Park, FL, USA.
³ Center for Translational Science, Florida International University, Port St. Lucie, FL, USA.
⁴ Department of Immunology and Nano-Medicine, Howard Wertheim College of Medicine, Florida International University, Miami, FL, 33199, USA.
⁵ Department of Cellular & Molecular Medicine, Herbert Wertheim College of Medicine, Miami, FL, USA.
⁶ Department of Pediatrics, University of California San Francisco, San Francisco, CA, 94143, USA; Department of Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA, 94143, USA.
⁷ Department of Cellular & Molecular Medicine, Herbert Wertheim College of Medicine, Miami, FL, USA; Center for Translational Science, Florida International University, Port St. Lucie, FL, USA; Department of Environmental Health Sciences, Robert Stempel College of Public Health and Social Work, University Park, FL, USA. Electronic address: stblack@fiu.edu.

PMID: 38734269
DOI: 10.1016/j.freeradbiomed.2024.05.019

Abstract

Higher levels of extracellular nicotinamide phosphoribosyltransferase (eNAMPT), a TLR4 agonist, are associated with poor clinical outcomes in sepsis-induced acute lung injury (ALI). Little is known regarding the mechanisms by which eNAMPT is involved in ALI. Our recent work has identified a crucial role for mitochondrial dysfunction in ALI. Thus, this study aimed to determine if eNAMPT-mediated inflammatory injury is associated with the loss of mitochondrial function. Our data show that eNAMPT disrupted mitochondrial bioenergetics. This was associated with cytoskeleton remodeling and the loss of endothelial barrier integrity. These changes were associated with enhanced mitochondrial fission and blocked when Rho-kinase (ROCK) was inhibited. The increases in mitochondrial fission were also associated with the nitration-mediated activation of the small GTPase activator of ROCK, RhoA. Blocking RhoA nitration decreased eNAMPT-mediated mitochondrial fission and endothelial barrier dysfunction. The increase in fission was linked to a RhoA-ROCK mediated increase in Drp1 (dynamin-related protein 1) at serine(S)⁶¹⁶. Another TLR4 agonist, lipopolysaccharide (LPS), also increased mitochondrial fission in a Drp1 and RhoA-ROCK-dependent manner. To validate our findings in vivo, we challenged C57BL/6 mice with eNAMPT in the presence and absence of the Drp1 inhibitor, Mdivi-1. Mdivi-1 treatment protected against eNAMPT-induced lung inflammation, edema, and lung injury. These studies demonstrate that mitochondrial fission-dependent disruption of mitochondrial function is essential in TLR4-mediated inflammatory lung injury and identify a key role for RhoA-ROCK signaling. Reducing mitochondrial fission could be a potential therapeutic strategy to improve ARDS outcomes.

Keywords: Acute lung injury; Cytoskeleton; Endothelial cell; Mitochondrial bioenergetics; Mitochondrial fission; ROS.