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FUTURE TRENDS
The use of BoNT continues to evolve, with new applications that deepen our understanding of clinical effect and mechanism of action. There have been anecdotal reports of tighter, smoother skin after BoNT-A injections, as well as a lower incidence of acne. Current research indicates that BoNT-A acts on the biological behavior of fibroblasts, including reducing production of matrix metalloproteinases (MMPs), responsible for the slow degradation of type I collagen, and stimulating the production of procollagen I. Collagen production and degradation has been investigated in vitro by measuring procollagen type I carboxyterminal peptide (PIP) and MMPs, respectively. Levels of PIP increased significantly when fibroblasts were grown in the presence of BoNT, with upregulation of type I collagen and a decrease in MMPs. In an in vivo investigation of the effects of BoNT on photodamaged skin, mice were pretreated with BoNT-A and subsequently irradiated with ultraviolet B light. Compared to control mice, those injected with BoNT-A had significantly decreased secretion of inflammatory cytokines associated with photodamage and postinflammatory hyperpigmentation.
Intradermal injection of BoNT-A has been used with success to treat oily skin and enlarged pores. When the T-zone (forehead and nose) was injected in a series of 20 patients, 17 reported an improvement in skin oiliness. Significantly lower sebum production was noted in 25 patients treated with 3 to 5โU of aboA in each of ten injection sites across the forehead, as measured by a sebometer. The authors speculated that blockade of local acetylcholine receptors in the pilosebaceous unit with BoNT-A could result in altered rates of sebum production.