COVID-19–Associated Acute Kidney Injury and Quantified Protein Catabolic Rate: A Likely Effect of Cytokine Storm on Muscle Protein Breakdown

We tested the role of interleukin-6 (IL-6) in sepsis-induced muscle proteolysis by determining ubiquitin mRNA levels and protein breakdown rates in incubated extensor digitorum longus muscles from septic and sham-operated IL-6 knockout and wild-type mice. In addition, the effect of treatment of mice with human recombinant IL-6 on muscle protein breakdown rates was determined. Finally, protein breakdown rates were measured in myotubes treated for up to 48 h with different concentrations of IL-6. Sepsis in wild-type mice resulted in an approximately ninefold increase in plasma IL-6 levels, whereas IL-6 was not detectable in plasma of sham-operated or septic IL-6 knockout mice. Total and myofibrillar muscle protein breakdown rates were increased by ∼30% and threefold, respectively, in septic IL-6 wild-type mice with an almost identical response noted in septic IL-6 knockout mice. Ubiquitin mRNA levels determined by dot blot analysis were increased during sepsis in muscles from both IL-6 knockout and wild-type mice, although the increase was less pronounced in IL-6 knockout than in wild-type mice. Treatment of normal mice or of cultured L6 myotubes with IL-6 did not influence protein breakdown rates. The present results suggest that IL-6 does not regulate muscle proteolysis during sepsis.

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Impact of sepsis-associated cytokine storm on plasma NGAL during acute kidney injury in a model of polymicrobial sepsis

Critical Care ◽

10.1186/cc12540 ◽

2013 ◽

Vol 17 (2) ◽

pp. 419 ◽

Cited By ~ 26

Author(s):

Gordon P Otto ◽

Martin Busch ◽

Maik Sossdorf ◽

Ralf A Claus

Keyword(s):

Acute Kidney Injury ◽

Kidney Injury ◽

Polymicrobial Sepsis ◽

Cytokine Storm ◽

Plasma Ngal

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Acute Effect of the Timing of Resistance Exercise and Nutrient Intake on Muscle Protein Breakdown

Nutrients ◽

10.3390/nu12041177 ◽

2020 ◽

Vol 12 (4) ◽

pp. 1177

Author(s):

Wataru Kume ◽

Jun Yasuda ◽

Takeshi Hashimoto

Keyword(s):

Resistance Exercise ◽

Nutrient Intake ◽

Plasma Insulin ◽

Muscle Protein ◽

Optimal Timing ◽

Protein Breakdown ◽

Mixed Meal ◽

Muscle Protein Breakdown ◽

Meal Intake ◽

Post Condition

Background: Combining resistance exercise (RE) with nutrient intake stimulates muscle protein net balance. However, it is still unclear whether the optimal timing of nutrient intake is before or after RE, especially on muscle protein breakdown (MPB) for an augmented muscle anabolic response. The aim of this study was to investigate the effect of a substantial mixed meal (i.e., nutrient- and protein-dense whole foods) before or after RE, compared with RE without a meal on the acute response of MPB in a crossover-design study. Methods: Eight healthy young men performed three trials: (1) meal intake before RE (Pre), (2) meal intake after RE (Post), and (3) RE without meal intake (No). Plasma insulin and 3-methylhistidine (3-MH), an MPB marker, were measured. Results: Time course change in plasma insulin level after RE was significantly higher in the Post condition than in the Pre and No conditions. The area under the curve of 3-MH concentration was significantly lower in the Post condition than in the Pre and No conditions. Conclusions: These results suggest that a substantial mixed meal immediately after RE may effectively suppress MPB in the morning.

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