Format

Send to

Choose Destination
Arthritis Res Ther. 2017 Jan 23;19(1):12. doi: 10.1186/s13075-016-1215-7.

Molecular alterations in skeletal muscle in rheumatoid arthritis are related to disease activity, physical inactivity, and disability.

Author information

1
Department of Medicine, Duke Molecular Physiology Institute, Duke School of Medicine, Durham, NC, USA. Huffm007@mc.duke.edu.
2
Department of Medicine, Duke Molecular Physiology Institute, Duke School of Medicine, Durham, NC, USA.
3
Biomedical Engineering, Duke University, Durham, NC, USA.
4
Harvard University School of Law, Boston, MA, USA.
5
Department of Surgery, Duke School of Medicine, Durham, NC, USA.
6
Department of Emergency Medicine, Indiana University, Indianapolis, IN, USA.
7
George Washington University, Washington, DC, USA.

Abstract

BACKGROUND:

To identify molecular alterations in skeletal muscle in rheumatoid arthritis (RA) that may contribute to ongoing disability in RA.

METHODS:

Persons with seropositive or erosive RA (n = 51) and control subjects matched for age, gender, race, body mass index (BMI), and physical activity (n = 51) underwent assessment of disease activity, disability, pain, physical activity and thigh muscle biopsies. Muscle tissue was used for measurement of pro-inflammatory markers, transcriptomics, and comprehensive profiling of metabolic intermediates. Groups were compared using mixed models. Bivariate associations were assessed with Spearman correlation.

RESULTS:

Compared to controls, patients with RA had 75% greater muscle concentrations of IL-6 protein (p = 0.006). In patients with RA, muscle concentrations of inflammatory markers were positively associated (p < 0.05 for all) with disease activity (IL-1β, IL-8), disability (IL-1β, IL-6), pain (IL-1β, TNF-α, toll-like receptor (TLR)-4), and physical inactivity (IL-1β, IL-6). Muscle cytokines were not related to corresponding systemic cytokines. Prominent among the gene sets differentially expressed in muscles in RA versus controls were those involved in skeletal muscle repair processes and glycolytic metabolism. Metabolic profiling revealed 46% higher concentrations of pyruvate in muscle in RA (p < 0.05), and strong positive correlation between levels of amino acids involved in fibrosis (arginine, ornithine, proline, and glycine) and disability (p < 0.05).

CONCLUSION:

RA is accompanied by broad-ranging molecular alterations in skeletal muscle. Analysis of inflammatory markers, gene expression, and metabolic intermediates linked disease-related disruptions in muscle inflammatory signaling, remodeling, and metabolic programming to physical inactivity and disability. Thus, skeletal muscle dysfunction might contribute to a viscous cycle of RA disease activity, physical inactivity, and disability.

KEYWORDS:

Fibrosis; Gene expression; Inflammation; Metabolomics; Satellite cells

PMID:
28114971
PMCID:
PMC5260091
DOI:
10.1186/s13075-016-1215-7
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for BioMed Central Icon for PubMed Central
Loading ...
Support Center