Diagnostic Value of Mitochondrial Dna and Peripheral Blood Mononuclear Cell Respirometry for Burn-Related Sepsis

Background Trauma-induced hypocalcemia is common and associated with adverse outcomes, but the mechanisms remain unclear. Thus, we aimed to characterize the metabolomic and proteomic differences between normo- and hypocalcemic trauma patients to illuminate biochemical pathways that may underlie a distinct pathology linked with this clinical phenomenon. Methods Plasma was obtained on arrival from injured patients at a Level 1 Trauma Center. Samples obtained after transfusion were excluded. Multiple regression was used to adjust the omics data for injury severity and arrival base excess prior to metabolome- and proteome-wide comparisons between normo- (ionized Ca2+ > 1.0 mmol/L) and hypocalcemic (ionized Ca2+ ≤ 1.0 mmol/L) patients using partial least squares-discriminant analysis. OmicsNet and Gene Ontology were used for network and pathway analyses, respectively. Results Excluding isolated traumatic brain injury and penetrating injury, the main analysis included 36 patients (n = 14 hypocalcemic, n = 22 normocalcemic). Adjusted analyses demonstrated distinct metabolomic and proteomic signatures for normo- and hypocalcemic patients. Hypocalcemic patients had evidence of mitochondrial dysfunction (TCA cycle disruption, dysfunctional fatty acid oxidation), inflammatory dysregulation (elevated DAMPs, activated endothelial cells), aberrant coagulation pathways, and proteolytic imbalance with increased tissue destruction. Conclusions Independent of injury severity, hemorrhagic shock, and transfusion, trauma-induced hypocalcemia is associated with early metabolomic and proteomic changes that may reflect unique pathology in hypocalcemic trauma patients. This study paves the way for future experiments to investigate mechanisms, identify intervenable pathways, and refine our management of hypocalcemia in severely injured patients.

Section: Discussionmentioning

confidence: 72%

Metabolomic and Proteomic Changes in Trauma-induced Hypocalcemia

Schaid,

LaCroix,

Cohen

et al. 2023

“…Furthermore, after thermal injury, ROS burden is significantly increased and associated with mitochondrial dysfunction in animal models (16). However, this signal was less clear in burn patients with infections (32). These data combined with the data presented here suggest that further investigation into ROS burden and mitochondrial damage in IP pediatric burn patients is warranted.…”

Section: Discussionmentioning

confidence: 98%

“…Furthermore, intravenous injection of isolated mtDNA from rat liver has been shown to illicit a strong inflammatory response in naive rats, resulting in similar lung injury as seen after thermal injury (11). A recent clinical study evaluating PBMC bioenergetics and mtDNA in a cohort of adults after thermal injury demonstrated an increased level of mtDNA in the burn patients compared with healthy controls (32). To our knowledge, this is the first study to evaluate circulating mtDNA in pediatric burn patients stratified based on immune function parameters.…”

Section: Discussionmentioning

confidence: 99%

Altered Profiles of Extracellular Mitochondrial Dna in Immunoparalyzed Pediatric Patients After Thermal Injury

Tetri,

Penatzer,

Tsegay

et al. 2023

Background Thermal injury is a major cause of morbidity and mortality in the pediatric population world-wide with secondary infection being the most common acute complication. Suppression of innate and adaptive immune function is predictive of infection in pediatric burn patients, but little is known about the mechanisms causing these effects. Circulating mtDNA which induces a proinflammatory signal, has been described in multiple disease states, but has not been studied in pediatric burn injuries. This study examined the quantity of circulating mtDNA and mtDNA mutations in immunocompetent (IC) and immunoparalyzed (IP) pediatric burn patients. Methods Circulating DNA was isolated from plasma of pediatric burn patients treated at Nationwide Children’s Hospital Burn Center at early (1-3 days) and late (4-7 days) time points post-injury. These patients were categorized as IP or IC based on previously established immune function testing and secondary infection. Three mitochondrial genes, D loop, ND1, and ND4, were quantified by multiplexed qPCR to assess both mtDNA quantity and mutation load. Results At the early timepoint, there were no differences in plasma mtDNA quantity, however IC patients had a progressive increase in mtDNA over time when compared to IP patients (change in ND1 copy number over time 3880 vs 87 copies/day, p = 0.0004). Conversely, the IP group had an increase in mtDNA mutation burden over time. Conclusions IC patients experienced a significant increase in circulating mtDNA quantity over time, demonstrating an association between increased mtDNA release, and proinflammatory phenotype in the burn patients. IP patients had significant increases in mtDNA mutation load likely representative of degree of oxidative damage. Together, these data provide further insight into the inflammatory and immunological mechanisms following pediatric thermal injury.

“…Mitochondrial dysfunction is a common pathological mechanism of sepsis-related organ damage (46,47), and improving mitochondrial dysfunction has been an important strategy to explore the treatment of sepsis-related organ damage (48). In recent years, excessive mitochondrial fission has been recognized as a marker of mitochondrial dysfunction (49), which could cause mitochondrial oxidative stress, promote mPTP opening, exacerbate proapoptotic protein leakage into the cytoplasm, and leading to activation of caspases resulting in apoptosis.…”

Section: Discussionmentioning

confidence: 99%

Sirtuin 5 Alleviates Excessive Mitochondrial Fission via Desuccinylation of Atpase Inhibitory Factor 1 in Sepsis-Induced Acute Kidney Injury

Li,

Yao,

Lei

et al. 2024

Sepsis-induced acute kidney injury (SAKI) poses a significant clinical challenge with high morbidity and mortality. Excessive mitochondrial fission has been identified as the central pathogenesis of sepsis-associated organ damage, which is also implicated in the early stages of SAKI. Sirtuin 5 (SIRT5) has emerged as a central regulator of cellular mitochondrial function; however, its role in the regulation of sepsis-induced excessive mitochondrial fission in kidney and the underlying mechanism remains unclear. In this study, SAKI was modeled in mice through cecal ligation and puncture (CLP), and in human renal tubular epithelial (HK-2) cells stimulated with lipopolysaccharide (LPS), to mimic the cell SAKI model. Our findings revealed that septic mice with a SIRT5 knockout (SIRT5 KO) exhibited shortened survival times and elevated levels of renal injury compared to wild-type (WT) mice, suggesting the significant involvement of SIRT5 in SAKI pathophysiology. Additionally, we observed that SIRT5 depletion led to increased renal mitochondrial fission, while the use of a mitochondrial fission inhibitor (Mdivi-1) reversed the detrimental effects caused by SIRT5 depletion, emphasizing the pivotal role of SIRT5 in preventing excessive mitochondrial fission. In vitro experiments demonstrated that the overexpression of SIRT5 effectively mitigated the adverse effects of LPS on HK-2 cells viability and mitochondrial fission. Conversely, downregulation of SIRT5 decreased HK-2 cells viability and exacerbated LPS-induced mitochondrial fission. Mechanistically, the protective function of SIRT5 may be in part, ascribed to its desuccinylating action on ATPase inhibitory factor 1 (ATPIF1). In conclusion, this study provides novel insights into the underlying mechanisms of SAKI, suggesting the possibility of identifying future drug targets in terms of improved mitochondrial dynamics by SIRT5.