For example, environmental factors like smoking, obesity, diabetes, and physical inactivity can induce immune dysfunction in susceptible individuals, resulting in increased production of pro-inflammatory cytokines such as interleukin-8 (IL-8), IL-17A, and tumor necrosis factor-alpha by inflammatory cells, and subsequent excessive production of neutrophil extracellular traps (NETs) (29, 30). Here, IL17A is linked to immune system disorder.