The relationship between plasma interleukin-15 levels and sarcopenia in outpatient older people

Background and aim Sarcopenia is a geriatric syndrome in which there is a decrease in muscle mass, muscle strength, and muscle function. Interleukin-15 (IL-15), a myokine released by skeletal muscle, has effects on both muscle and adipose tissue. We evaluated the relationship between plasma IL-15 level and sarcopenia. Methods We evaluated a total of 160 outpatient older people, and 80 of whom had sarcopenia. Sarcopenia was defined according to the European Working Group on Sarcopenia in Older People criteria. Plasma IL-15 was measured by enzyme-linked immunosorbent assay. Activities of daily living, nutritional and exercise status, co-morbidities, body mass index, waist circumference, sensitive C-reactive protein, IL-6, and vitamin D levels were also evaluated. Results IL-15 levels were significantly higher in control subjects [5.1 (2.75-18.69)] compared to sarcopenic participants [3.91 (2.07-15.56)] (p < 0.001). Plasma IL-15 levels were independently and inversely associated with sarcopenia in multivariate regression analysis [OR: 0.74 (CI 95% 0.6-0.91) p = 0.005]. Age [OR: 1.13 (CI 95% 1.01-1.27) p = 0.03] and BMI [OR: 0.68 (CI 95% 0.51-0.92)] were also associated with sarcopenia in multivariate regression analysis. Conclusions and discussion A low level of plasma IL-15 is associated with sarcopenia in outpatient older people. Further longitudinal and prospective studies are needed to evaluate changes in IL-15 over time together with muscle mass and strength or therapeutic potential of IL-15.