Meanwhile, respiratory diseases themselves can induce the production of various cytokines, such as interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF) α, that exert effects on the intestinal tract (36, –, 38), thereby disrupting the balance of gut microbiota and potentially influencing the subsequent development of gastrointestinal disorders (39). Here, IL6 is linked to respiratory system disorder.