Altered dynamics of lipid metabolism in muscle cells from patients with idiopathic inflammatory myopathy is ameliorated by 6 months of training

Vitamin D and its receptor in skeletal muscle are associated with muscle disease manifestation, lipid metabolism and physical fitness of patients with myositis

BACKGROUND

Low levels of vitamin D have been associated with several autoimmune diseases. A growing body of evidence supports the association of vitamin D with skeletal muscle damage, regeneration, and energy and lipid metabolism. The aim was to analyse vitamin D and its receptor (VDR) in the muscle tissue of patients with idiopathic inflammatory myopathies (IIM) and to relate them to clinical parameters and muscle lipid and energy metabolism.

METHODS

Forty-six patients with IIM and 67 healthy controls (HC) were included in the study. 27 IIM patients participated in a 24-week exercise intervention. Muscle biopsies were obtained from 7 IIM patients before/after training, 13 non-exercising IIM controls, and 21 HC. Circulating concentrations of 25(OH)D and 1,25(OH)D were measured. Gene expression of VDR and CYP27B1, the enzyme converting 25(OH)D to hormonally active 1,25(OH)D, was determined by qPCR in muscle tissue and primary muscle cells. Lipid oxidative metabolism was assessed in muscle tissue (mRNA, qPCR) and primary muscle cells (radioactive assays).

RESULTS

Lower levels of active 1,25(OH)D were observed in IIM patients compared with HC (mean ± SD: 125.0 ± 45.4 vs. 164.7 ± 49.2 pmol/L; p < 0.0001). 25(OH)D was associated with CRP (r = -0.316, p = 0.037), MITAX (r = -0.311, p = 0.040) and HAQ (r = -0.390, p = 0.009) in IIM. After 24 weeks of training, active 1,25(OH)D was associated with MMT8 (r = 0.866, p < 0.0001), FI-2 (r = 0.608, p = 0.013) and HAQ (r = -0.537, p = 0.032). Gene expression of both VDR and CYP27B1 in primary muscle cells decreased after training (p = 0.031 and p = 0.078, respectively). Associations of VDR mRNA in muscle tissue with MMT-8 (IIM: r = -0.559, p = 0.013), serum CK (HC: r = 0.484, p = 0.031), myoglobin (IIM: r = 0.510, p = 0.026) and myostatin (IIM: r = -0.519, p = 0.023) were observed. The expression of VDR in differentiated muscle cells correlated negatively with the complete oxidation of palmitic acid (r = -0.532, p = 0.028). Muscle mRNA of carnitine palmitoyl transferase 1 (CPT1) (downregulated in IIM, p = 0.001) correlated positively with serum 1,25(OH) vitamin D (r = 0.410, p = 0.042).

CONCLUSION

Reduced biologically active vitamin D in circulation suggests its impaired metabolism in IIM. Serum vitamin D levels and gene expression of its receptor and activating enzyme in muscle tissue were modified by regular exercise and associated with disease manifestations, physical fitness, and muscle lipid metabolism of IIM patients.

Immunometabolic shifts in autoimmune disease: Mechanisms and pathophysiological implications

Autoimmune diseases occur when the immune system abnormally attacks the body's normal tissues, causing inflammation and damage. Each disease has unique immune and metabolic dysfunctions during pathogenesis. In rheumatoid arthritis (RA), immune cells have different metabolic patterns and mitochondrial/lysosomal dysfunctions at different disease stages. In systemic lupus erythematosus (SLE), type I interferon (IFN) causes immune cell metabolic dysregulation, linking activation to metabolic shifts that may worsen the disease. In systemic sclerosis (SSc), mitochondrial changes affect fibroblast metabolism and the immune response. Idiopathic inflammatory myopathies (IIMs) patients have mitochondrial and metabolic issues. In primary Sjögren's syndrome (pSS), immune cell metabolism is imbalanced and mitochondrial damage can lead to cell/tissue damage. Metabolic reprogramming links cellular energy needs and immune dysfunctions, causing inflammation, damage, and symptoms in these diseases. It also affects immune cell functions like differentiation, proliferation, and secretion. This review discusses the potential of targeting metabolic pathways to restore immune balance, offering directions for future autoimmune disease research and treatment.

High-intensity resistance training improves quality of life, muscle endurance and strength in patients with myositis: a randomised controlled trial

Myositis is associated with reduced quality of life, which is accompanied by significant impairments in muscle endurance and strength, altogether representing cardinal traits in patients with myositis. This randomised controlled trial aimed to investigate the effect of high-intensity resistance training on quality of life in patients with myositis. Thirty-two patients with established, stable myositis were randomised to 16 weeks of high-intensity resistance training (intervention group) or 16 weeks of usual care (control group). Primary outcome was quality of life assessed as the change in the physical component summary score (PCS) of the Short Form-36 health questionnaire from baseline to post-intervention. Secondary outcomes included functional capacity measures, such as functional index 3, and International Myositis Assessment and Clinical Studies Group (IMACS) disease activity and damage core set measures, including manual muscle testing 8 (MMT8). The primary outcome PCS showed an improvement in favour of high-intensity resistance training with a between-group difference of 5.33 (95% CI 0.61; 10.05) (p = 0.03). Additionally, functional index 3 showed a between-group difference indicating greater gains with high-intensity resistance training 11.49 (95% CI 3.37; 19.60) (p = 0.04), along with a between-group improvement in MMT8 1.30 (95% CI 0.09; 2.51) (p = 0.04). High-intensity resistance training for 16 weeks effectively improved quality of life in patients with myositis. Clinical measures of muscle endurance and muscle strength were also found to improve with high-intensity resistance training, while patients stayed in disease remission. Consequently, progressively adjusted high-intensity resistance training is feasible and causes no aggravation of the disease, while benefitting patients with myositis.Clinical trial registration: Clinicaltrials.gov ID: NCT04486261- https://clinicaltrials.gov/study/NCT04486261 .

The effect of a 24-week training focused on activities of daily living, muscle strengthening, and stability in idiopathic inflammatory myopathies: a monocentric controlled study with follow-up

BACKGROUND

The structural and functional changes of the skeletal muscles in idiopathic inflammatory myopathies (IIM) caused by inflammation and immune changes can be severely disabling. The objective of this study was to assess the effect of a 24-week program combining a supervised training of activities of daily living (ADL), resistance, and stability with home exercise for improving muscle function, compared to a daily home-based exercise representing the regular outpatient care.

METHODS

Fifty-seven patients with IIM were consecutively and non-selectively enrolled in an intervention (IG, n = 30) or control (CG, n = 27) group. Both groups were provided a standard-of-care pharmacological treatment and follow-up. Only the IG underwent the supervised intervention twice a week for 1 h per session. At baseline, 12, 24, and 48 weeks, all patients were assessed by an assessor blinded to the intervention for primary outcomes: muscle strength (Manual Muscle Testing of eight muscle groups [MMT-8]) and endurance (Functional Index-2 [FI-2]), and secondary outcomes: stability and body composition. Secondary outcomes also included questionnaires evaluating disability (Health Assessment Questionnaire [HAQ]), quality of life (Short Form 36 [SF-36]), depression (Beck's Depression Inventory-II [BDI-II]), and fatigue (Fatigue Impact Scale [FIS]), and analysis of the systemic and local inflammatory response and perceived exertion to assess the safety of the intervention.

RESULTS

Twenty-seven patients in the IG and 23 in the CG completed the entire program and follow-up. At week 24, compared to deterioration in the CG, we found a significant improvement in the IG in muscle strength (mean % improvement compared to baseline by 26%), endurance (135%), disability (39%), depression (26%), stability (11%), and basal metabolism (2%) and a stabilization of fitness for physical exercise. The improvement was clinically meaningful (a 24-week change by >20%) in most outcomes in a substantial proportion of patients. Although the improvement was still present at 48 weeks, the effect was not sustained during follow-up. No significant increase in the systemic or local expression of inflammatory markers was found throughout the intervention.

CONCLUSIONS

This 24-week supervised intervention focused on ADL training proved to be safe and effective. It not only prevented the progressive deterioration, but also resulted in a significant improvement in muscle strength, endurance, stability, and disability, which was clinically meaningful in a substantial proportion of patients.

TRIAL REGISTRATION

ISRCTN35925199 (retrospectively registered on 22 May 2020).