Mesenchymal Stromal Cells Deficient in Autophagy Proteins Are Susceptible to Oxidative Injury and Mitochondrial Dysfunction

Abstract

Oxidative stress resulting from inflammatory responses that occur during acute lung injury and sepsis can initiate changes in mitochondrial function. Autophagy regulates cellular processes in the setting of acute lung injury, sepsis, and oxidative stress by modulating the immune response and facilitating turnover of damaged cellular components. We have shown that mesenchymal stromal cells (MSCs) improve survival in murine models of sepsis by also regulating the immune response. However, the effect of autophagy on MSCs and MSC mitochondrial function during oxidative stress is unknown. This study investigated the effect of depletion of autophagic protein microtubule-associated protein 1 light chain 3B (LC3B) and beclin 1 (BECN1) on the response of MSCs to oxidative stress. MSCs were isolated from wild-type (WT) and LC3B 2/2 or Becn1 1/2 mice. MSCs from the LC3B 2/2 and Becn1 1/2 animals had increased susceptibility to oxidative stress-induced cell death as compared with WT MSCs. The MSCs depleted of autophagic proteins also had impaired mitochondrial function (decreased intracellular ATP, reduced mitochondrial membrane potential, and increased mitochondrial reactive oxygen species production) under oxidative stress as compared with WT MSCs. In WT MSCs, carbon monoxide (CO) preconditioning enhanced autophagy and mitophagy, and rescued the cells from oxidative stress-induced death. CO preconditioning was not able to rescue the decreased survival of MSCs from the LC3B 2/2 and Becn1 1/2 animals, further supporting the tenet that CO exerts its cytoprotective effects via the autophagy pathway.

A phase I trial of low-dose inhaled carbon monoxide in sepsis-induced ARDS

“…We selected once-daily iCO treatment based on prior work demonstrating both safety and activation of mitochondrial biogenesis in healthy volunteers after once-daily iCO treatment (200 ppm for 60 minutes) on 5 consecutive days (17,25). Preclinical studies have shown that CO treatment for short periods of time induces transcriptional programs of mitochondrial biogenesis (9,17,50,51) and induces autophagy (11,15,52), suggesting that once-daily dosing of CO could be effective, in contrast to continuous administration, as with NO. Once-daily iCO dosing also optimizes subject safety by ensuring that CO accumulation over sequential days will not occur as treatments are separated by 4-6 half-lives for CO elimination.…”

Mesenchymal Stromal Cells Modulate Macrophages in Clinically Relevant Lung Injury Models by Extracellular Vesicle Mitochondrial Transfer

“…They observed that normoxia (21% oxygen) induced oxidative stress, thereby promoting mitophagy in MSCs. Ghanta and colleagues then demonstrated the importance of autophagy in maintaining healthy mitochondrial function and promoting survival in MSCs during oxidative stress (29). The influence of mitochondrial transfer on macrophage phenotype, however, has not been studied extensively.…”

Insights into superoxide dismutase 3 in regulating biological and functional properties of mesenchymal stem cells

“…During the early stage of hydrogen peroxideinduced injury, autophagic flux found to be activated as a self-defensive mechanism [38]. Similarly, depletion of autophagic proteins such as Microtubule-associated proteins 1A/1B light chain 3B (LC3B) and beclin-1 in MSCs found to exaggerate oxidative stress-induced injury with decreased intracellular ATP and increased ROS [39]. Endogenous SOD3 level was found to regulate autophagic induction under normal and nutrientdeprived conditions as the expression of both SOD3 and LC3-II found to increase from 3 h and declined subsequently after 48 h [37].…”