Ascorbic acid reduces Ropivacaine-induced myotoxicity in cultured human osteoporotic skeletal muscle cells.

BACKGROUND: Osteoporosis is a worldwide health issue. Loss of bone mass is a potential risk factor for fragility fractures, and osteoporotic fractures place a considerable burden on society. Bone and muscle represent a functional unit in which the two tissues are intimately interconnected. Ropivacaine is a potent local anesthetic used in clinical practice for intraoperative anesthesia and postoperative pain management, in particular for hip surgery. When injected, Ropivacaine can diffuse locally through, in particular in surrounding skeletal muscle tissue, causing dose-dependent cytotoxicity, oxidative stress and myogenesis impairment. Based on those evidences, we focused our attention on Ropivacaine-induced cytotoxicity on cultured human myoblasts. METHODS: Primary human myoblasts and myotubes from healthy subjects, osteoarthritic and osteoporotic patients (OP) were cultured in the presence of Ropivacaine. In some experiments, ascorbic acid (AsA) was added as a potent antioxidant agent. Cell viability and ROS levels were evaluated to investigate the myotoxic activity and Real-Time PCR and Western blot analysis carried out to investigate the expression of proliferation and myogenic markers. RESULTS: A dose-dependent decrease of cell viability was observed after Ropivacaine exposure in both OP myoblasts and myotubes cultures, whereas those effects were not observed in the presence of Propofol, a general anesthetic. The adding of AsA reduced Ropivacaine negative effects in OP myoblast cultures. In addition, Ropivacaine exposure also increased ROS levels and upregulated Nox4 expression, an enzyme primarily implicated in skeletal muscle ROS generation. AsA treatment counteracted the oxidant activity of Ropivacaine and partially restored the basal condition in cultures. Positive myogenic markers, such as MyoD and Myf5, were downregulated by Ropivacaine exposure, whereas myostatin, a negative regulator of muscle growth and differentiation, was upregulated. The phenotypic deregulation of myogenic controllers in the presence of Ropivacaine was counteracted by AsA treatment. CONCLUSIONS: Our findings highlight the oxidative stress-mediated myotoxic effect of Ropivacaine on human skeletal muscle tissue cell cultures, and suggest treatment with AsA as valid strategy to mitigate its negative effects and allowing an ameliorated functional skeletal muscle recovery in patients undergoing hip replacement surgery for osteoporotic bone fracture.

Adverse effects of systemic cancer therapy on skeletal muscle: myotoxicity comes out of the closet.

PURPOSE OF REVIEW: Systemic cancer therapy-associated skeletal muscle wasting is emerging as a powerful impetus to the overall loss of skeletal muscle experienced by patients with cancer. This review explores the clinical magnitude and biological mechanisms of muscle wasting during systemic cancer therapy to illuminate this adverse effect. Emerging strategies for mitigation are also discussed. RECENT FINDINGS: Clinical findings include precise, specific measures of muscle loss over the course of chemotherapy, targeted therapy and immunotherapy. All these therapeutic classes associate with quantitatively important muscle loss, independent of tumor response. Parallel experimental studies provide understanding of the specific molecular basis of wasting, which can include inhibition of protein synthesis, proliferation and differentiation, and activation of inflammation, reactive oxygen species, autophagy, mitophagy, apoptosis, protein catabolism, fibrosis and steatosis in muscle. Strategies to mitigate these muscle-specific adverse effects of cancer therapy remain in the earliest stages of development. SUMMARY: The adverse side effect of cancer therapy on skeletal muscle has been largely ignored in the development of cancer therapeutics. Given the extent to which loss of muscle mass and function can bear on patients' function and quality of life, protection/mitigation of these side effects is a research priority.

Emerging PD-1 and PD-1L inhibitors-associated myopathy with a characteristic histopathological pattern.

BACKGROUND AND OBJECTIVE: Drug-induced myopathy is among the most common causes of muscle disease. An association has recently been described between programmed death-1 (PD-1)/PD-1 ligand (PD-L1) inhibitors and immune-related adverse events (irAE) affecting the muscle. Here, we report the clinical and pathological findings of nine unrelated patients with PD-1 and PD-L1 inhibitors-associated myopathy. METHODS: We retrospectively analyzed 317 muscle biopsies performed for diagnostic purposes from January 2017 to June 2019. Patients were attended in two tertiary centers and muscle biopsies were performed and analyzed by two myology experts. Muscle biopsies were frozen in cooled isopenthane, cryostat sectioned and stained. Immunohistochemistry studies were also performed as a routine procedure in our lab. RESULTS: We identified 9 patients receiving anti-PD-1 or PD-L1 inhibitors consulting for either muscle weakness, asthenia, myasthenic-like syndrome or other muscle related-symptoms, along with biopsy-proven inflammatory myopathy. One had concomitant myocarditis. In most of the cases muscle biopsy showed a marked phenomenon of necrosis, macrophagy and muscle regeneration with perivascular inflammatory infiltrates with a large component of macrophagic cells. A tendency to perifascicular atrophy was also noticed. The expression of MHC class I antigens predominated in the perifascicular zones. Raised muscle enzymes were detected in 7 patients. CONCLUSION: A characteristic clinic-pathological pattern, including a myasthenia gravis-like syndrome plus myositis was found in patients receiving PD-1 and PD-1 L inhibitors. A large component of macrophages resembling granulomas seems to be the pathological hallmark of the syndrome. Further information is required to understand the wide spectrum of immune-related adverse events involving the muscle during or after treatment with anti-PD-1 inhibitors, but the pathological picture seems to be characteristic.

PGC-1α plays a pivotal role in simvastatin-induced exercise impairment in mice.

AIM: Statins decrease cardiovascular complications, but can induce myopathy. Here, we explored the implication of PGC-1α in statin-associated myotoxicity. METHODS: We treated PGC-1α knockout (KO), PGC-1α overexpression (OE) and wild-type (WT) mice orally with 5 mg simvastatin kg-1  day-1 for 3 weeks and assessed muscle function and metabolism. RESULTS: In WT and KO mice, but not in OE mice, simvastatin decreased grip strength, maximal running distance and vertical power assessed by ergometry. Post-exercise plasma lactate concentrations were higher in WT and KO compared to OE mice. In glycolytic gastrocnemius, simvastatin decreased mitochondrial respiration, increased mitochondrial ROS production and free radical leak in WT and KO, but not in OE mice. Simvastatin increased mRNA expression of Sod1 and Sod2 in glycolytic and oxidative gastrocnemius of WT, but decreased it in KO mice. OE mice had a higher mitochondrial DNA content in both gastrocnemius than WT or KO mice and simvastatin exhibited a trend to decrease the citrate synthase activity in white and red gastrocnemius in all treatment groups. Simvastatin showed a trend to decrease the mitochondrial volume fraction in both muscle types of all treatment groups. Mitochondria were smaller in WT and KO compared to OE mice and simvastatin further reduced the mitochondrial size in WT and KO mice, but not in OE mice. CONCLUSIONS: Simvastatin impairs skeletal muscle function, muscle oxidative metabolism and mitochondrial morphology preferentially in WT and KO mice, whereas OE mice appear to be protected, suggesting a role of PGC-1α in preventing simvastatin-associated myotoxicity.