Sepsis Disrupts Mitochondrial Function and Diaphragm Morphology

Frontiers in Physiology

卷:12

Wagner Seixas da-Silva¹  Anderson Teixeira Santos¹  Juliana Woyames²  Patricia Rieken Macedo Rocco³  Natália Blanco³  Johnatas Dutra Silva³  Pedro Leme Silva³  Flavia Fonseca Bloise⁴  Cherley Borba Vieira Andrade⁴  Thamires Siqueira Oliveira⁴  Tânia Maria Ortiga-Carvalho⁴  Nazareth de Novaes Rocha⁵ 

[1] Laboratory of Metabolic Adaptations, Institute of Medical Biochemistry Leopoldo de Meis, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil;

[2] Laboratory of Molecular Endocrinology, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil;

[3] Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil;

[4] Laboratory of Translational Endocrinology, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil;

[5] Physiology and Pharmacology Department, Biomedical Institute, Fluminense Federal University, Niteroi, Brazil;

关键词: diaphragm;    sepsis;    mitochondria;    CLP;    oxidative phosphorylation;    muscle;   

DOI  :  10.3389/fphys.2021.704044

来源: DOAJ

【 摘 要 】

BackgroundThe diaphragm is the primary muscle of inspiration, and its dysfunction is frequent during sepsis. However, the mechanisms associated with sepsis and diaphragm dysfunction are not well understood. In this study, we evaluated the morphophysiological changes of the mitochondrial diaphragm 5 days after sepsis induction.MethodsMale C57Bl/6 mice were divided into two groups, namely, cecal ligation and puncture (CLP, n = 26) and sham-operated (n = 19). Mice received antibiotic treatment 8 h after surgery and then every 24 h until 5 days after surgery when mice were euthanized and the diaphragms were collected. Also, diaphragm function was evaluated in vivo by ultrasound 120 h after CLP. The tissue fiber profile was evaluated by the expression of myosin heavy chain and SERCA gene by qPCR and myosin protein by using Western blot. The Myod1 and Myog expressions were evaluated by using qPCR. Diaphragm ultrastructure was assessed by electron microscopy, and mitochondrial physiology was investigated by high-resolution respirometry, Western blot, and qPCR.ResultsCecal ligation and puncture mice developed moderated sepsis, with a 74% survivor rate at 120 h. The diaphragm mass did not change in CLP mice compared with control, but we observed sarcomeric disorganization and increased muscle thickness (38%) during inspiration and expiration (21%). Septic diaphragm showed a reduction in fiber myosin type I and IIb mRNA expression by 50% but an increase in MyHC I and IIb protein levels compared with the sham mice. Total and healthy mitochondria were reduced by 30% in septic mice, which may be associated with a 50% decrease in Ppargc1a (encoding PGC1a) and Opa1 (mitochondria fusion marker) expressions in the septic diaphragm. The small and non-functional OPA1 isoform also increased 70% in the septic diaphragm. These data suggest an imbalance in mitochondrial function. In fact, we observed downregulation of all respiratory chain complexes mRNA expression, decreased complex III and IV protein levels, and reduced oxygen consumption associated with ADP phosphorylation (36%) in CLP mice. Additionally, the septic diaphragm increased proton leak and downregulated Sod2 by 70%.ConclusionThe current model of sepsis induced diaphragm morphological changes, increased mitochondrial damage, and induced functional impairment. Thus, diaphragm damage during sepsis seems to be associated with mitochondrial dysfunction.

【 授权许可】

Unknown