TNF and chronic apical periodontitis: Moreover, they elucidated miR-146a acted as an anti-inflammatory mediator and negatively regulated the expression of IL-6, IL-1β, and TNF-α.24 They also confirmed Hey2 was a target gene of miR-146a and negatively regulated miR-146a, IL-6, IL-1β, and TNF-α expressions, suggesting that miR-146a and Hey2 form a mutual negative feedback regulatory loop in chronic apical periodontitis.24