Acute muscle loss and early effects of COVID-19 on skeletal muscle in adult patients: A retrospective cohort study

OBJECTIVES

It is known that COVID-19 has multisystemic effects. However, its early effects on muscle tissue have not been clearly elucidated. The aim of this study is to investigate early changes in the pectoral muscle in patients with COVID-19 infection.

MATERIALS AND METHODS

The pectoral muscle areas (PMA) and pectoral muscle index (PMI) of 139 patients diagnosed with COVID-19 were measured from chest CTs taken at the time of the first diagnosis and within 6 months after the diagnosis. The effect of the infection on the muscle area was investigated by evaluating whether there was a change between the two measurements. Lung involvement of the infection in the first CT was scored with the CT severity score (CT-SS). In addition, the effects of patients' clinics, CT-SS, length of hospital stay, and intubation history on changes in the muscle area were investigated.

RESULTS

When the PMA and PMI values were compared, there was a statistically significant decrease in the values in the control CT group compared to the first diagnosis CT group. The difference was found higher in intubated patients. CT-SS was associated with a decrease in PMI.

CONCLUSION

COVID-19 is one of the causes of acute sarcopenia. Pectoralis muscle is part of the skeletal muscle, and there may be a decrease in the muscle area in the early period of the disease.

Peripheral T helper subset profiling in idiopathic inflammatory myositis: Proof of concept

INTRODUCTION

There is a dearth of biomarkers in Idiopathic Inflammatory Myopathies (IIM) to recognize ongoing muscle inflammation and distinguish damage from activity. Since IIM is an autoantibody-mediated disease with tertiary lymphoid organogenesis reported in the diseased muscles, we aimed to study the peripheral blood T helper (Th) subset profiling as a plausible reflection of ongoing muscle inflammation.

METHODS

Fifty-six patients of IIM were compared with 21 healthy controls (HC) and 18 patients with sarcoidosis. Th1, Th17, Th17.1, and Treg cells were identified after stimulation assays (BD Biosciences). Myositis autoantibodies were tested by line immunoassay (Euroimmune, Germany).

RESULTS

All Th subsets were elevated in IIM as compared with HC. As compared to HC, PM had elevated Th1 and Treg while Th17 and Th17.1 populations were higher in OM. Patients with sarcoidosis had higher Th1 and Treg but lower Th17 population as compared to IIM {Th1(69.1% vs 49.65%, p<0.0001), {Treg (12.05% vs 6.2%, p<0.0001), {Th17 (2.49% vs 4.4%, p<0.0001)}. Similar results were obtained when sarcoidosis ILD was compared with IIM ILD with a higher Th1 and Treg population but lower Th17 population in the former. No difference in T cell profile was observed after stratification for MSA positivity, type of MSA, clinical features of IIM and disease activity.

CONCLUSION

Th subsets in IIM are distinct from sarcoidosis and HC with a TH17 predominant paradigm, creating a case of exploring Th17 pathway and IL-17 blockers for the treatment of IIM. However, cell profiling cannot distinguish active from inactive disease limiting its predictive potential as a biomarker of activity in IIM.