Intermuscular adipose tissue in patients with systemic lupus erythematosus

Abstract

ObjectivePatients with SLE frequently have debilitating fatigue and reduced physical activity. Intermuscular adipose tissue (IMAT) accumulation is associated with reduced physical exercise capacity. We hypothesised that IMAT is increased in patients with SLE and associated with increased fatigue, reduced physical activity and increased inflammation.MethodsIn a cross-sectional study, 23 patients with SLE and 28 control participants were evaluated. IMAT was measured in the calf muscles using sequentialT1-weighted MRI. Patient-reported physical activity and fatigue were measured and a multiplex proteomic assay was used to measure markers and mediators of inflammation.ResultsIMAT accumulation (percentage of IMAT area to muscle area) was significantly higher in SLE versus control participants (7.92%, 4.51%–13.39% vs 2.65%, 1.15%–4.61%, median, IQR, p<0.001) and remained significant after adjustment for age, sex, race and body mass index (p<0.001). In patients with SLE, IMAT accumulation did not differ significantly among corticosteroid users and non-users (p=0.48). In the study cohort (patients and controls), IMAT was positively correlated with self-reported fatigue score (rho=0.52, p<0.001) and inversely correlated with self-reported walking distance (rho=−0.60, p<0.001). Several markers of inflammation were associated with IMAT accumulation in patients with SLE, and gene ontology analysis showed significant enrichment for pathways associated with macrophage migration and activation in relation to IMAT.ConclusionPatients with SLE have greater IMAT accumulation than controls in the calf muscles. Increased IMAT is associated with greater fatigue and lower physical activity. Future studies should evaluate the effectiveness of interventions that improve muscle quality to alleviate fatigue in patients with SLE.

Potential of bone morphogenetic protein-7 in treatment of lupus nephritis: addressing the hurdles to implementation

“…For example, patients with SLE werereported to exhibit greater extent of visceral adipose tissue deposition than controls (Li et al 2019 ), which—together with the greater perivascular adipose depots reported in rheumatic diseases including SLE (Shi et al 2022 )—predisposes them for cardiovascular complications. As reported for other rheumatic diseases such as RA (Baker et al 2018 ), intermuscular adipose tissue deposition is also reported in SLE (Gamboa et al 2022 ) and contributes significantly to poorer long-term strength of patients. In addition, given the large number of adipokines secreted within adipose tissue, it is not unexpected that obesity has been identified as a major contributor to sustained pro-inflammatory dysregulation and disease progression in rheumatic disease (Versini et al 2014 ), as well as specifically in renal inflammation and fibrosis (Declèves and Sharma 2015 ).…”

Anti‐Inflammatory Effect of High‐Density Lipoprotein Blunted by Delivery of Altered MicroRNA Cargo in Patients With Rheumatoid Arthritis

“…Serum lipoproteins were measured by nuclear magnetic resonance and analyzed by the Bruker IVDr Lipoprotein Subclass Analysis, as previously described. 21 HDL purification. HDL was separated from 8 mL plasma by density-gradient ultracentrifugation for sequential isolation of lipoprotein-containing subfractions using potassium bromide: very low-density lipoprotein (1.006-1.018 g/mL), LDL (1.019-1.063 g/mL), and HDL (1.064-1.021 g/mL), as previously described.…”

“…High‐sensitivity CRP was measured in the Vanderbilt University Medical Center Hospital Laboratory. Serum lipoproteins were measured by nuclear magnetic resonance and analyzed by the Bruker IVDr Lipoprotein Subclass Analysis, as previously described 21 …”

Intermuscular adipose tissue accumulation is associated with higher tissue sodium in healthy individuals

“…IMAT was segmented using an automated unsupervised learning algorithm, specifically k‐means clustering, to separate areas of IMAT from the muscle segmentation in the fat‐weighted Dixon MRI image. The IMAT segmentation was then used to calculate the percentage of IMAT area relative to total muscle area (%) at the level of the mid‐calf (Gamboa et al., 2022 ; Sahinoz et al., 2020 ).…”