miR‐223: infection, inflammation and cancer

Expression of the micro RNA miR‐223 is deregulated during influenza or hepatitis B infection and in inflammatory bowel disease, type 2 diabetes, leukaemia and lymphoma. Although this may also be the result of the disease per se , increasing evidence suggests a role for miR‐223 in limiting inflammation to prevent collateral damage during infection and in preventing oncogenic myeloid transformation. Validated targets for miR‐223 that have effects on inflammation and infection include granzyme B, IKK α, Roquin and STAT 3. With regard to cancer, validated targets include C/ EBP β, E2F1, FOXO 1 and NFI ‐A. The effect of miR‐223 on these targets has been documented individually; however, it is more likely that miR‐223 affects multiple targets simultaneously for key processes where the micro RNA is important. Such processes include haematopoietic cell differentiation, particularly towards the granulocyte lineage (where miR‐223 is abundant) and as cells progress down the myeloid lineage (where miR‐223 expression decreases). NF ‐κB and the NLRP 3 inflammasome are important inflammatory mechanisms that are dampened by miR‐223 in these cell types. The mi RNA can also directly target viruses such as HIV , leading to synergistic effects during infection. Here we review the recent studies of miR‐223 function to show how it modulates inflammation, infection and cancer development.