Figure 4
From: Toll-like receptor 2 activation and comedogenesis: implications for the pathogenesis of acne
A model of TLR activation and the life-cycle of acne. A) P. acnes colonises the sebaceous gland and stimulates infundibular keratinocytes to release inflammatory cytokines (ICs) including IL-1α via TLR activation. B) ICs, including IL-1α, stimulate hypercornification, thus formation of the comedone. C) IC secretion, including IL-1α, is also associated with a reduction in lipogenesis in basal sebocytes, thereby reducing the sebum levels and starving the P. acnes of nutrients. D) Reduction in P. acnes levels reduces IC secretion, resolution of the comedone and restoration of sebocyte maturation. Adapted from Downie MM et al.[3].