Anti-IL15RA monoclonal antibody, clone FQ7774

Objective Interleukin (IL) -2 receptor subunit regulates lymphocyte activation, which plays an important role in atherosclerosis. Associations between soluble IL-2R (sIL-2R) and cardiovascular disease (CVD) have not been widely studied and little is known about the genetic determinants of sIL-2R levels. Approach and Results We measured baseline levels of sIL-2R in 4408 European American (EA) and 766 African American (AA) adults from the Cardiovascular Health Study (CHS) and examined associations with baseline CVD risk factors, subclinical CVD, and incident CVD events. We also performed a genome-wide association study for sIL-2R in CHS (2964 EAs and 683 AAs) and further combined CHS EA results with those from two other EA cohorts in a meta-analysis (n=4464 EAs). In age, sex- and race- adjusted models, sIL-2R was positively associated with current smoking, type 2 diabetes mellitus, hypertension, insulin, waist circumference, C-reactive protein, IL-6, fibrinogen, internal carotid wall thickness, all-cause mortality, CVD mortality, and incident CVD, stroke, and heart failure. When adjusted for baseline CVD risk factors and subclinical CVD, associations with all-cause mortality, CVD mortality, and heart failure remained significant in both EAs and AAs. In the EA genome-wide association study analysis, we observed 52 single-nucleotide polymorphisms in the chromosome 10p15-14 region, which contains IL2RA, IL15RA, and RMB17, that reached genome-wide significance (P<5x10(-8)). The most significant single-nucleotide polymorphism was rs7911500 (P=1.31x10(-75)). The EA meta-analysis results were highly consistent with CHS-only results. No single-nucleotide polymorphisms reached statistical significance in the AAs. Conclusions These results support a role for sIL-2R in atherosclerosis and provide evidence for multiple-associated single-nucleotide polymorphisms at chromosome 10p15-14.

Interleukin-15 (IL-15) is a putative myokine hypothesized to induce an oxidative skeletal muscle phenotype. The specific IL-15 receptor alpha subunit (IL-15R alpha) has also been implicated in specifying this contractile phenotype. The purposes of this study were to determine the muscle-specific effects of IL-15R alpha functional deficiency on skeletal muscle isometric contractile properties, fatigue characteristics, spontaneous cage activity, and circulating IL-15 levels in male and female mice. Muscle creatine kinase (MCK)-driven IL-15R alpha knockout mice (mIl15ra(fl/fl)/Cre(+)) were generated using the Cre-loxP system. We tested the hypothesis that IL-15R alpha functional deficiency in skeletal muscle would increase resistance to contraction-induced fatigue, cage activity, and circulating IL-15 levels. There was a significant effect of genotype on the fatigue curves obtained in extensor digitorum longus (EDL) muscles from female mIl15ra(fl/fl)/Cre(+) mice, such that force output was greater during the repeated contraction protocol compared with mIl15ra(fl/fl)/Cre(+) control mice. Muscles from female mIl15ra(fl/fl)/Cre(+) mice also had a twofold greater amount of the mitochondrial genome-specific COXII gene compared with muscles from mIl15ra(fl/fl)/Cre(+) control mice, indicating a greater mitochondrial density in these skeletal muscles. There was a significant effect of genotype on the twitch: tetanus ratio in EDL and soleus muscles from mIl15ra(fl/fl)/Cre(+) mice, such that the ratio was lower in these muscles compared with mIl15ra(fl/fl)/Cre(+) control mice, indicating a pro-oxidative shift in muscle phenotype. However, spontaneous cage activity was not different and IL-15 protein levels were lower in male and female mIl15ra(fl/fl)/Cre(+) mice compared with control. Collectively, these data support a direct effect of muscle IL-15R alpha deficiency in altering contractile properties and fatigue characteristics in skeletal muscles.