Action of tocilizumab on energy expenditure in rheumatoid arthritis: A prospective study using calorimetry and actimetry

Effects of biologic and target synthetic disease-modifying anti-rheumatic drugs on sarcopenia in spondyloarthritis and rheumatoid arthritis: a systematic review and meta-analysis

Sarcopenia is a syndrome defined by generalized and progressive loss of skeletal muscle mass, strength, and function. Besides affecting elderly population, it is actually common among inflammatory rheumatic diseases (IRD) patients. We performed a systematic literature review with a meta-analysis to investigate the influence of biologic and target synthetic disease-modifying anti-rheumatic drugs (bDMARDs/tsDMARDs) on sarcopenia in IRD. A systematic search has been performed on Pubmed, Scopus, and Web of science. Studies characteristics were collected. Assessment tools were body composition (total lean mass (TLM) and percentage, appendicular skeletal mass (ASM), fat-free mass and index (FFM and FFMI), skeletal mass index (SMI) and segmental lean mass (SLM)), and muscle strength and physical performance tests. Treatment effect defined the difference in change from baseline to the end of follow-up treatment was divided by the pooled SD of the difference. Twenty-two studies on 778 patients receiving bDMARDs/tsDMARDs and 157 controls were reviewed. They investigated rheumatoid arthritis (RA) (N = 14), spondyloarthritis (SpA) (N = 6), psoriatic arthritis (N = 1), and both RA and SpA (N = 1). tsDMARDs were used in one study with no effect on sarcopenia. Ten studies demonstrated that bDMARDs increased significantly muscle measures in 347 patients (44.6%) with a significant increase in TLM (6/15 studies; 57.4%), FFMI (4/6 studies; 59.9%), ASM (2/5 studies; 17.6%), SMI (2/5 studies; 18.1%), and SLM (2/2 studies; 3.6%). bDMARDs showed also a positive effect on handgrip strength in 1/3 of studies (45.2%) and on physical performance in 1/2 of studies (61%). In 1/5 of comparative studies, IRD patients on bDMARDs showed significantly higher increase of TLM in comparison to controls naïve bDMARDs. Regarding diagnosis, positive effect of bDMARDs was seen in 67.4% in SpA versus 49.3% in RA, with a significant increase of TLM, ASM and FFMI in 59.4%, 100%, and 65.2% in SpA versus 54.9%, 24.1%, and 54.8% in RA, respectively. Meta-analysis assessed the effect of bDMARD on TLM in 10 studies. There was no statistically significant difference [SMD - 0.10 (95% Confidence Interval - 0.26 - 0.06; tau² = 0). Heterogeneity across studies was null, and the 95% confidence interval (index of precision) was equal to the 95% predictive interval. The first systematic literature review showed that bDMARDs have a significant improve effect in nearly half of RA and SpA patients on muscle mass and muscle strength, assessed separately. However, the meta-analysis concluded that bDMARDs have no significant effect on TLM.

Interaction effect of systemic inflammation and modifiable rheumatoid cachexia risk factors on resting energy expenditure in patients with rheumatoid arthritis

Background

In rheumatoid cachexia (RC), high resting energy expenditure (REE) is associated with loss of muscle mass driven by proinflammatory cytokines. The objectives of this study were to investigate parameters associated with RC, and the interaction between systemic inflammation and modifiable risk factors for RC on REE.

Methods

Thirty-five rheumatoid arthritis (RA) and nineteen non-RA controls comparable in age, sex, race and BMI underwent measures of REE by indirect calorimetry. Clinical, dietary, body composition and physical function data were collected. Homeostasis model assessment for insulin resistance (HOMA-IR) and serum interleukin-6 (IL-6) were used as parameters of IR and systemic inflammation, respectively. Regression models tested association between REE and dependent variables, including pre-specified interaction tests involving HOMA-IR and IL-6 and dietary intake of protein per weight (PPW) and IL-6.

Results

RA subjects were mostly women (94%) and had a median age of 54 years (50.5, 70) and BMI of 30.5 kg/m2 (26.1, 36.9). We observed a significant interaction effect between PPW and serum IL-6 on REE among RA subjects in the multiple regression model among RA. The upper tertile of PPW demonstrated a significant negative correlation between REE and IL-6 (β=-19.97, 95% CI [-35.41, -4.54], p=0.01). The lower tertile of PPW demonstrated a significant positive correlation between REE and IL-6 (β=42.24, 95% CI [4.25, 80.23], p=0.03).

Conclusions

While IR can lead to muscle catabolism, IR was not significantly associated with REE in RA individuals. Higher dietary protein intake could attenuate the effect of systemic inflammation on REE in RA patients.

The Interrelations between Biological and Targeted Synthetic Agents Used in Inflammatory Joint Diseases, and Obesity or Body Composition

Obesity is a comorbidity that plays a role in the development and severity of inflammatory joint diseases, including rheumatoid arthritis, psoriatic arthritis and axial spondyloarthritis. The relationships between obesity and adipose tissue and the treatments given for inflammatory joint diseases are bidirectional. In fact, biological agents (bDMARDs) and targeted synthetic agents (tsDMARDs) may influence body weight and body composition of treated patients, while obesity in turn may influence clinical response to these agents. Obesity is a prevalent comorbidity mainly affecting patients with rheumatoid arthritis (RA) and psoriatic arthritis (PsA) with specific phenotypes. Tumour necrosis factor alpha (TNFα) inhibitors have been associated with changes in body composition by improving lean mass, but also by significantly increasing fat mass, which localized toward the abdominal/visceral region. The IL-6 inhibitor tocilizumab is associated with an increase in lean mass without change in fat mass. The clinical response to TNFα inhibitors is attenuated by obesity, an effect that is less pronounced with IL-6 inhibitors and the B-cell depletion agent rituximab. Conversely, body weight has no influence on the response to the costimulation inhibitor abatacept. These effects may be of help to the physician in personalized medicine, and may guide the therapeutic choice in obese/overweight patients.