Tag: skeletal muscle

Maximal oxidative capacity during exercise is associated with muscle power output in patients with long coronavirus disease 2019 (COVID-19) syndrome. A moderation analysis

Abstract:

Background & aims: Long COVID syndrome (LCS) involves persistent symptoms experienced by many patients after recovering from coronavirus disease 2019 (COVID-19). We aimed to assess skeletal muscle energy metabolism, which is closely related to substrate oxidation rates during exercise, in patients with LCS compared with healthy controls. We also examined whether muscle power output mediates the relationship between COVID-19 and skeletal muscle energy metabolism.

Methods: In this cross-sectional study, we enrolled 71 patients with LCS and 63 healthy controls. We assessed clinical characteristics such as body composition, physical activity, and muscle strength. We used cardiopulmonary exercise testing to evaluate substrate oxidation rates during graded exercise. We performed statistical analyses to compare group characteristics and peak fat oxidation differences based on power output.

Results: The two-way analysis of covariance (ANCOVA) results, adjusted for covariates, showed that the patients with LCS had lower absolute maximal fatty acid oxidation (MFO), relative MFO/fat free mass (FFM), absolute carbohydrates oxidation (CHox), relative CHox/FFM, and oxygen uptake (V˙˙O2) at maximum fat oxidation (g min-1) than the healthy controls (P < 0.05). Moderation analysis indicated that muscle power output significantly influenced the relationship between LCS and reduced peak fat oxidation (interaction β = -0.105 [95% confidence interval -0.174; -0.036]; P = 0.026). Therefore, when muscle power output was below 388 W, the effect of the LCS on MFO was significant (62% in our study sample P = 0.010). These findings suggest compromised mitochondrial bioenergetics and muscle function, represented by lower peak fat oxidation rates, in the patients with LCS compared with the healthy controls.

Conclusion: The patients with LCS had lower peak fat oxidation during exercise compared with the healthy controls, potentially indicating impairment in skeletal muscle function. The relationship between peak fat oxidation and LCS appears to be mediated predominantly by muscle power output. Additional research should continue investigating LCS pathogenesis and the functional role of mitochondria.

Source: Ramírez-Vélez R, Oscoz-Ochandorena S, García-Alonso Y, García-Alonso N, Legarra-Gorgoñon G, Oteiza J, Lorea AE, Izquierdo M, Correa-Rodríguez M. Maximal oxidative capacity during exercise is associated with muscle power output in patients with long coronavirus disease 2019 (COVID-19) syndrome. A moderation analysis. Clin Nutr ESPEN. 2023 Dec;58:253-262. doi: 10.1016/j.clnesp.2023.10.009. Epub 2023 Oct 14. PMID: 38057014. https://clinicalnutritionespen.com/article/S2405-4577(23)02166-6/fulltext (Full text)

Respiratory SARS-CoV-2 Infection Causes Skeletal Muscle Atrophy and Long-Lasting Energy Metabolism Suppression

Abstract:

Muscle fatigue represents the most prevalent symptom of long-term COVID, with elusive pathogenic mechanisms. We performed a longitudinal study to characterize histopathological and transcriptional changes in skeletal muscle in a hamster model of respiratory SARS-CoV-2 infection and compared them with influenza A virus (IAV) and mock infections.

Histopathological and bulk RNA sequencing analyses of leg muscles derived from infected animals at days 3, 30, and 60 post-infection showed no direct viral invasion but myofiber atrophy in the SARS-CoV-2 group, which was accompanied by persistent downregulation of the genes related to myofibers, ribosomal proteins, fatty acid β-oxidation, tricarboxylic acid cycle, and mitochondrial oxidative phosphorylation complexes.

While both SARS-CoV-2 and IAV infections induced acute and transient type I and II interferon responses in muscle, only the SARS-CoV-2 infection upregulated TNF-α/NF-κB but not IL-6 signaling in muscle. Treatment of C2C12 myotubes, a skeletal muscle cell line, with combined IFN-γ and TNF-α but not with IFN-γ or TNF-α alone markedly impaired mitochondrial function.

We conclude that a respiratory SARS-CoV-2 infection can cause myofiber atrophy and persistent energy metabolism suppression without direct viral invasion. The effects may be induced by the combined systemic interferon and TNF-α responses at the acute phase and may contribute to post-COVID-19 persistent muscle fatigue.

Source: Homma ST, Wang X, Frere JJ, Gower AC, Zhou J, Lim JK, tenOever BR, Zhou L. Respiratory SARS-CoV-2 Infection Causes Skeletal Muscle Atrophy and Long-Lasting Energy Metabolism Suppression. Biomedicines. 2024 Jun 28;12(7):1443. doi: 10.3390/biomedicines12071443. PMID: 39062017; PMCID: PMC11275164. https://pmc.ncbi.nlm.nih.gov/articles/PMC11275164/ (Full text)

Persistent Fatigue, Weakness, and Aberrant Muscle Mitochondria in Survivors of Critical COVID-19

Abstract:

Objectives: Persistent skeletal muscle dysfunction in survivors of critical illness due to acute respiratory failure is common, but biological data elucidating underlying mechanisms are limited. The objective of this study was to elucidate the prevalence of skeletal muscle weakness and fatigue in survivors of critical illness due to COVID-19 and determine if cellular changes associate with persistent skeletal muscle dysfunction.

Design: A prospective observational study in two phases: 1) survivors of critical COVID-19 participating in physical outcome measures while attending an ICU Recovery Clinic at short-term follow-up and 2) a nested cohort of patients performed comprehensive muscle and physical function assessments with a muscle biopsy; data were compared with non-COVID controls.

Setting: ICU Recovery Clinic and clinical laboratory.

Patients/subjects: Survivors of critical COVID-19 and non-COVID controls.

Interventions: None.

Measurements and main results: One hundred twenty patients with a median of 56 years old (interquartile range [IQR], 42-65 yr old), 43% female, and 33% individuals of underrepresented race attended follow-up 44 ± 17 days after discharge. Patients had a median Acute Physiology and Chronic Health Evaluation-II score of 24.0 (IQR, 16-29) and 98 patients (82%) required mechanical ventilation with a median duration of 14 days (IQR, 9-21 d). At short-term follow-up significant physical dysfunction was observed with 93% of patients reporting generalized fatigue and performing mean 218 ± 151 meters on 6-minute walk test (45% ± 30% of predicted). Eleven patients from this group agreed to participate in long-term assessment and muscle biopsy occurring a mean 267 ± 98 days after discharge. Muscle tissue from COVID exhibited a greater abundance of M2-like macrophages and satellite cells and lower activity of mitochondrial complex II and complex IV compared with controls.

Conclusions: Our findings suggest that aberrant repair and altered mitochondrial activity in skeletal muscle associates with long-term impairments in patients surviving an ICU admission for COVID-19.

Source: Mayer KP, Ismaeel A, Kalema AG, Montgomery-Yates AA, Soper MK, Kern PA, Starck JD, Slone SA, Morris PE, Dupont-Versteegden EE, Kosmac K. Persistent Fatigue, Weakness, and Aberrant Muscle Mitochondria in Survivors of Critical COVID-19. Crit Care Explor. 2024 Oct 16;6(10):e1164. doi: 10.1097/CCE.0000000000001164. PMID: 39412208; PMCID: PMC11487221. https://pmc.ncbi.nlm.nih.gov/articles/PMC11487221/ (Full text)

Muscular metabolic plasticity in 3D in vitro models against systemic stress factors in ME/CFS and long COVID-19

Abstract:

Myalgic encephalomyelities/ chronic fatigue syndrome and long COVID-19 are clinically challenging, multi-symptomatic conditions with multiple overlapping symptoms. Unfortunately, contemporary research is directly being done on patients which risks exacerbating their symptoms. Using our 3-D in vitro skeletal muscle tissues we have mapped the progression of functional, physiological, and metabolic adaptations of the tissues in response to patient sera over time.

During short exposure we treated the tissues for 48 hours with patient sera. The contractile profiles of these tissues were severely compromised. Transcriptomic analyses of these short exposure samples showed an absence of significant differentially expressed genes between ME/CFS and LC-19. The analyses revealed an upregulation of glycolytic enzymes especially of PDK4, suggesting a switch away from Oxidative Phosphorylation as well as a decline in DRP1, involved in mitochondrial fission.

Subsequent structural analyses confirmed hypertrophy in myotubes and hyperfused mitochondrial networks. Mitochondrial oxygen consumption capacity, evaluated through the MitoStress test, was also elevated, as was the non-mitochondrial respiration confirming the shift to glycolysis.

Interestingly, at short exposures of 48 hours, the muscle tissues appeared to be adapting to the stress factors by upregulating glycolysis and increasing the muscular metabolic volume. Prolonging the exposure to 96 and 144 hours induced high fatiguability, and fragility in tissues. The mitochondria, at longer exposures, appeared to be fragmented and assumed a toroidal conformation indicating a change in mitochondrial membrane potential.

We hypothesize that the disease progresses through an intermediary stress-induced hypermetabolic state, ultimately leading to severe deterioration of muscle function. This is the first account of research that proposes acquired metabolic plasticity in 3D skeletal muscles exposed to ME/CFS and Long COVID-19 sera.

Source: S. Mughal, F. Andújar-Sánchez, M. Sabater-Arcis, J. Fernández-Costa, J. Ramón-Azcón. 571P Muscular metabolic plasticity in 3D in vitro models against systemic stress factors in ME/CFS and long COVID-19. Neuromuscular Disorders, Volume 43, Supplement 1, October 2024, 104441.162. https://www.sciencedirect.com/science/article/abs/pii/S0960896624003353

Myalgic encephalomyelitis/chronic fatigue syndrome from current evidence to new diagnostic perspectives through skeletal muscle and metabolic disturbances

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a demanding medical condition for patients and society. It has raised much more public awareness after the COVID-19 pandemic since ME/CFS and long-COVID patients share many clinical symptoms such as debilitating chronic fatigue. However, unlike long COVID, the etiopathology of ME/CFS remains a mystery despite several decades’ research.

This review moves from pathophysiology of ME/CFS through the compelling evidence and most interesting hypotheses. It focuses on the pathophysiology of skeletal muscle by proposing the hypothesis that skeletal muscle tissue offers novel opportunities for diagnosis and treatment of this syndrome and that new evidence can help resolve the long-standing debate on terminology.

Source: Pietrangelo T, Cagnin S, Bondi D, Santangelo C, Marramiero L, Purcaro C, Bonadio RS, Di Filippo ES, Mancinelli R, Fulle S, Verratti V, Cheng X. Myalgic encephalomyelitis/chronic fatigue syndrome from current evidence to new diagnostic perspectives through skeletal muscle and metabolic disturbances. Acta Physiol (Oxf). 2024 Mar 14:e14122. doi: 10.1111/apha.14122. Epub ahead of print. PMID: 38483046. https://pubmed.ncbi.nlm.nih.gov/38483046/

Muscle abnormalities worsen after post-exertional malaise in long COVID

Abstract:

A subgroup of patients infected with SARS-CoV-2 remain symptomatic over three months after infection. A distinctive symptom of patients with long COVID is post-exertional malaise, which is associated with a worsening of fatigue- and pain-related symptoms after acute mental or physical exercise, but its underlying pathophysiology is unclear.

With this longitudinal case-control study (NCT05225688), we provide new insights into the pathophysiology of post-exertional malaise in patients with long COVID. We show that skeletal muscle structure is associated with a lower exercise capacity in patients, and local and systemic metabolic disturbances, severe exercise-induced myopathy and tissue infiltration of amyloid-containing deposits in skeletal muscles of patients with long COVID worsen after induction of post-exertional malaise. This study highlights novel pathways that help to understand the pathophysiology of post-exertional malaise in patients suffering from long COVID and other post-infectious diseases.

Source: Appelman, B., Charlton, B.T., Goulding, R.P. et al. Muscle abnormalities worsen after post-exertional malaise in long COVID. Nat Commun 15, 17 (2024). https://doi.org/10.1038/s41467-023-44432-3 https://www.nature.com/articles/s41467-023-44432-3 (Full text)

Microvascular Capillary and Precapillary Cardiovascular Disturbances Strongly Interact to Severely Affect Tissue Perfusion and Mitochondrial Function in ME/CFS Evolving from the Post COVID-19 Syndrome

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a frequent, debilitating and still enigmatic disease. There is a broad overlap in the symptomatology of ME/CFS and the Post-COVID Syndrome (PCS). A fraction of the PCS patients develops the full clinical picture of ME/CFS.
New observations in microvessels and blood from patients suffering from PCS have appeared and include microclots and malformed pathological blood cells. Capillary blood flow is impaired not only by pathological blood components but also by prothrombotic changes in the vascular wall, endothelial dysfunction, and expression of adhesion molecules in the capillaries. These disturbances can finally cause a low capillary flow and even capillary stasis. A low cardiac stroke volume due to hypovolemia and the inability of the capacitance vessels to adequately constrict to deliver the necessary cardiac preload generate an unfavorable low precapillary perfusion pressure.
Furthermore, a predominance of vasoconstrictor over vasodilator influences exists, in which sympathetic hyperactivity and endothelial dysfunction play a strong role, causing constriction of resistance vessels and of precapillary sphincters which leads to a fall in capillary pressure behind the sphincters. The interaction of these two precapillary cardiovascular mechanisms causing a low capillary perfusion pressure is hemodynamically highly unfavorable in the presence of a primary capillary stasis already caused by the pathological blood components and their interaction with the capillary wall, to severely impair organ perfusion.
The detrimental coincidence of the microcirculatory with the precapillary cardiovascular disturbances may constitute the key disturbance of the Post-COVID-19 syndrome and finally lead to ME/CFS in pre-disposed patients because the interaction causes a particular kind of perfusion disturbance – capillary ischemia-reperfusion – which has a high potential of causing mitochondrial dysfunction by inducing sodium- and calcium-overload in skeletal muscles. The latter in turns worsens the vascular situation by the generation of reactive oxygen species to close a vicious cycle from which the patient can hardly escape.
Source: Wirth, K.J.; Löhn, M. Microvascular Capillary and Precapillary Cardiovascular Disturbances Strongly Interact to Severely Affect Tissue Perfusion and Mitochondrial Function in ME/CFS Evolving from the Post COVID-19 Syndrome. Preprints 2023, 2023120791. https://doi.org/10.20944/preprints202312.0791.v1  https://www.preprints.org/manuscript/202312.0791/v1 (Full text available as PDF file)

Post-COVID exercise intolerance is associated with capillary alterations and immune dysregulations in skeletal muscles

Abstract:

The SARS-CoV-2 pandemic not only resulted in millions of acute infections worldwide, but also in many cases of post-infectious syndromes, colloquially referred to as “long COVID”. Due to the heterogeneous nature of symptoms and scarcity of available tissue samples, little is known about the underlying mechanisms.

We present an in-depth analysis of skeletal muscle biopsies obtained from eleven patients suffering from enduring fatigue and post-exertional malaise after an infection with SARS-CoV-2. Compared to two independent historical control cohorts, patients with post-COVID exertion intolerance had fewer capillaries, thicker capillary basement membranes and increased numbers of CD169+ macrophages. SARS-CoV-2 RNA could not be detected in the muscle tissues.

In addition, complement system related proteins were more abundant in the serum of patients with PCS, matching observations on the transcriptomic level in the muscle tissue. We hypothesize that the initial viral infection may have caused immune-mediated structural changes of the microvasculature, potentially explaining the exercise-dependent fatigue and muscle pain.

Source: Aschman, T., Wyler, E., Baum, O. et al. Post-COVID exercise intolerance is associated with capillary alterations and immune dysregulations in skeletal muscles. acta neuropathol commun 11, 193 (2023). https://doi.org/10.1186/s40478-023-01662-2 https://actaneurocomms.biomedcentral.com/articles/10.1186/s40478-023-01662-2 (Full text)

Post-acute Sequelae of SARS Co-V2 and Chronic Fatigue/Myalgic Encephalitis Share Similar Pathophysiologic Mechanisms of Exercise Limitation

Abstract:

Abstract available online: https://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A6470

Source: S. Jothi, G. Claessen, M. Insel, S. Kubba, E. Howden, S.-R. Carmona, F.P. Rischard. Post-acute Sequelae of SARS Co-V2 and Chronic Fatigue/Myalgic Encephalitis Share Similar Pathophysiologic Mechanisms of Exercise Limitation. https://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A6470

Sarcopenia as potential biological substrate of long COVID-19 syndrome: prevalence, clinical features, and risk factors

Abstract:

Background: Severe clinical pictures and sequelae of COVID-19 disease are immune mediated and characterized by a ‘cytokine storm’. Skeletal muscle has emerged as a potent regulator of immune system function. The aim of the present study is to define the prevalence of sarcopenia among COVID-19 survivors and the negative impact of sarcopenia on the post-acute COVID-19 syndrome and its related risk factors.

Methods: A total of 541 subjects recovered from COVID-19 disease were enrolled in the Gemelli Against COVID-19 Post-Acute Care between April 2020 and February 2021. They underwent a multidisciplinary clinical evaluation and muscle strength and physical performance assessment.

Results: Mean age was 53.1 years (SD 15.2, range from 18 to 86 years), and 274 (51%) were women. The prevalence of sarcopenia was 19.5%, and it was higher in patients with a longer hospital stay and lower in patients who were more physically active and had higher levels of serum albumin. Patients with sarcopenia had a higher number of persistent symptoms than non-sarcopenic patients (3.8 ± 2.9 vs. 3.2 ± 2.8, respectively; P = 0.06), in particular fatigue, dyspnoea, and joint pain.

Conclusions: Sarcopenia identified according to the EWGSOP2 criteria is high in patients recovered from COVID-19 acute illness, particularly in those who had experienced the worst clinical picture reporting the persistence of fatigue and dyspnoea. Our data suggest that sarcopenia, through the persistence of inflammation, could be the biological substrate of long COVID-19 syndrome. Physical activity, especially if associated with adequate nutrition, seems to be an important protective factor.

Source: Martone AM, Tosato M, Ciciarello F, Galluzzo V, Zazzara MB, Pais C, Savera G, Calvani R, Marzetti E, Robles MC, Ramirez M, Landi F; Gemelli Against COVID-19 Post-Acute Care Team. Sarcopenia as potential biological substrate of long COVID-19 syndrome: prevalence, clinical features, and risk factors. J Cachexia Sarcopenia Muscle. 2022 Jun 14. doi: 10.1002/jcsm.12931. Epub ahead of print. PMID: 35698920. https://onlinelibrary.wiley.com/doi/10.1002/jcsm.12931 (Full text)