Interleukin-2 (IL-2) and interleukin 6 (IL-6) are two commonly used markers of inflammation, and increased expression of both IL-2 and IL-6 has been shown in cardiovascular disease [20], COPD [21] [22], loneliness [23]–[25] and depression [26] [27]. This evidence concerns the gene IL6 and chronic obstructive pulmonary disease.