Low Levels of Lipopolysaccharide Modulate Mitochondrial Oxygen Consumption in Skeletal Muscle

Frisard, Madlyn I.; Wu, Yuqi; McMillan, Ryan P.; Voelker, Kevin A.; Wahlberg, Kristin A.; Anderson, Angela S.; Boutagy, Nabil E.; Resendes, Kyle; Ravussin, Éric; Hulver, Matthew W.

doi:10.1016/j.metabol.2014.11.007

Cited by 43 publications

(39 citation statements)

References 64 publications

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“…1). Although reduced maximum respiration has been described recently for LPS exposure (21), the increase in basal respiration in our investigation is unique for the HS stimulation. These findings may be partly explained by the role of soluble HS as an endogenous danger-associated molecule (22).…”

Section: Heparan Sulfate Alters Myocardial Mitochondrial Functionmentioning

confidence: 56%

Soluble Heparan Sulfate in Serum of Septic Shock Patients Induces Mitochondrial Dysfunction in Murine Cardiomyocytes

Märtin¹,

Peters²,

Schmitz³

et al. 2015

Shock

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The heart is one of the most frequently affected organs in sepsis. Recent studies focused on lipopolysaccharide-induced mitochondrial dysfunction; however myocardial dysfunction is not restricted to gram-negative bacterial sepsis. The purpose of this study was to investigate circulating heparan sulfate (HS) as an endogenous danger associated molecule causing cardiac mitochondrial dysfunction in sepsis. We used an in vitro model with native sera (SsP) and sera eliminated from HS (HS-free), both of septic shock patients, to stimulate murine cardiomyocytes. As determined by extracellular flux analyzing, SsP increased basal mitochondrial respiration, but reduced maximum mitochondrial respiration, compared with unstimulated cells (P < 0.0001 and P < 0.0001, respectively). Cells stimulated with HS-free serum revealed unaltered basal and maximum mitochondrial respiration, compared with unstimulated cells (P = 0.1174 and P = 0.8992, respectively). Cellular ATP-level were decreased in SsP-stimulated cells but unaltered in cells stimulated with HS-free serum compared with unstimulated cells (P < 0.0001 and P = 0.1593, respectively). Live-cell imaging revealed an increased production of mitochondrial reactive oxygen species in cells stimulated with SsP compared with cells stimulated with HS-free serum (P < 0.0001). Expression of peroxisome proliferator-activated receptors (PPARα and PPARγ) and their co-activators PGC-1α, which regulate mitochondrial function, were studied using PCR. Cells stimulated with SsP showed downregulated PPARs and PGC-1α mRNA-levels compared with HS-free serum (P = 0.0082, P = 0.0128, and P = 0.0185, respectively). Blocking Toll-like receptor 4 revealed an inhibition of HS-dependent downregulation of PPARs and PGC-1α (all P < 0.0001). In conclusion, circulating HS in serum of septic shock patients cause cardiac mitochondrial dysfunction, suggesting that HS may be targets of therapeutics in septic cardiomyopathy.

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Section: Heparan Sulfate Alters Myocardial Mitochondrial Functionmentioning

confidence: 56%

Soluble Heparan Sulfate in Serum of Septic Shock Patients Induces Mitochondrial Dysfunction in Murine Cardiomyocytes

Märtin¹,

Peters²,

Schmitz³

et al. 2015

Shock

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“…According to the reverse Randle cycle, it is possible that the LPS induced rise in circulating FFA could reduce glucose uptake and oxidation without impairing insulin signaling 78, 79 . These observations are in contrast to a switch to preferential glucose oxidation over fatty acid oxidation in the fasting period in rodent skeletal muscle following acute LPS exposure 41, 42 . However it is important to note that these studies use different LPS dosing paradigms, therefore the continuous infusion of LPS over 360 minutes in the former study 75 may alter skeletal muscle metabolism differently than a single LPS injection or short LPS exposure 41, 42 .…”

Section: Metabolic Endotoxemia and Obesity: Evidence In Humansmentioning

confidence: 61%

“…This data suggests that the metabolic perturbations in skeletal muscle are due, at least in part, to NFκB translocation via LPS-TLR4 activation. Follow-up studies in C2C12 cells demonstrated decrements in mitochondrial respiration following short-term (2 hour), low dose (50 pg/mL) LPS treatment 42 . In addition, co-treatment with LPS and the antioxidant, n-acetyl-cysteine (NAC), prevented changes in cellular mitochondrial respiration and changes in basal substrate metabolism previously reported (Figure 2A–D).…”

Section: Metabolic Endotoxemia and Obesity: Evidence In Rodentsmentioning

confidence: 94%

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Metabolic endotoxemia with obesity: Is it real and is it relevant?

et al. 2016

Self Cite

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Obesity is associated with metabolic derangements in multiple tissues, which contribute to the progression of insulin resistance and the metabolic syndrome. The underlying stimulus for these metabolic derangements in obesity are not fully elucidated, however recent evidence in rodents and humans suggests that systemic, low level elevations of gut derived endotoxin (lipopolysaccharide, LPS) may play an important role in obesity related, whole-body and tissue specific metabolic perturbations. LPS initiates a well-characterized signaling cascade that elicits many pro-and anti-inflammatory pathways when bound to its receptor, Toll-Like Receptor 4 (TLR4). Low-grade elevation in plasma LPS has been termed “metabolic endotoxemia” and this state is associated with a heightened pro-inflammatory and oxidant environment often observed in obesity. Given the role of inflammatory and oxidative stress in the etiology of obesity related cardio-metabolic disease risk, it has been suggested that metabolic endotoxemia may serve a key mediator of metabolic derangements observed in obesity. This review provides supporting evidence of mechanistic associations with cell and animal models, and provides complimentary evidence of the clinical relevance of metabolic endotoxemia in obesity as it relates to inflammation and metabolic derangements in humans. Discrepancies with endotoxin detection are considered, and an alternate method of reporting metabolic endotoxemia is recommended until a standardized measurement protocol is set forth.

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“…Mitochondria were isolated as previously described from ~ 75 -100 mg of red skeletal muscle 13 . Between 5 -10 µg/µl of mitochondrial protein will be attained from this amount of tissue by resuspending the final mitochondrial pellet in ≤50 µl of isolation buffer for mitochondria (IBM) 2 (See Frisard et al (Table 3) and injections (Table 4-5) and adjust pH as desired (pH 7.4).…”

Section: Protocolmentioning

confidence: 99%

Using Isolated Mitochondria from Minimal Quantities of Mouse Skeletal Muscle for High throughput Microplate Respiratory Measurements

Boutagy

Rogers²,

Pyne

et al. 2015

JoVE

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Skeletal muscle mitochondria play a specific role in many disease pathologies. As such, the measurement of oxygen consumption as an indicator of mitochondrial function in this tissue has become more prevalent. Although many technologies and assays exist that measure mitochondrial respiratory pathways in a variety of cells, tissue and species, there is currently a void in the literature in regards to the compilation of these assays using isolated mitochondria from mouse skeletal muscle for use in microplate based technologies. Importantly, the use of microplate based respirometric assays is growing among mitochondrial biologists as it allows for high throughput measurements using minimal quantities of isolated mitochondria. Therefore, a collection of microplate based respirometric assays were developed that are able to assess mechanistic changes/adaptations in oxygen consumption in a commonly used animal model. The methods presented herein provide step-bystep instructions to perform these assays with an optimal amount of mitochondrial protein and reagents, and high precision as evidenced by the minimal variance across the dynamic range of each assay.

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Low Levels of Lipopolysaccharide Modulate Mitochondrial Oxygen Consumption in Skeletal Muscle

Cited by 43 publications

References 64 publications

Soluble Heparan Sulfate in Serum of Septic Shock Patients Induces Mitochondrial Dysfunction in Murine Cardiomyocytes

Soluble Heparan Sulfate in Serum of Septic Shock Patients Induces Mitochondrial Dysfunction in Murine Cardiomyocytes

Metabolic endotoxemia with obesity: Is it real and is it relevant?

Using Isolated Mitochondria from Minimal Quantities of Mouse Skeletal Muscle for High throughput Microplate Respiratory Measurements

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