Pathogen infection can polarise macrophages to the M1-phenotype, resulting in the production of high levels of pro-inflammatory cytokines such as interleukin (IL)-6 and tumour necrosis factor (TNF)-α, or effector molecules inducible nitric oxide synthase (iNOS) and surface markers cluster of differentiation (CD)11c or CD86, exert a pro-inflammatory effect and defense against pathogens. Here, NOS2 is linked to infection.