Topical applications of an emollient reduce circulating pro-inflammatory cytokine levels in chronically aged humans: a pilot clinical study.

Abstract

While increased levels of circulating inflammatory cytokines in chronologically aged humans have been linked to the development of ageing-associated chronic disorders (e.g., cardiovascular disease, type II diabetes, osteoporosis and Alzheimer's disease), approaches that reduce circulating cytokines are not yet available. In chronologically aged mice, we recently demonstrated that epidermal dysfunction largely accounts for age-associated elevations in circulating cytokine levels, and that improving epidermal function reduced circulating cytokine levels. We performed a pilot study to determine whether improving epidermal function reduces circulating pro-inflammatory cytokine levels in aged humans. Thirty-three aged humans were topically treated twice-daily for 30days, with≈3mL of an emollient, previously shown to improve epidermal function, while untreated, aged humans and a cohort of young volunteers served as controls. Changes in epidermal function and levels of three key, age-related, plasma cytokines (IL-1β, IL-6 and TNFα) were measured at baseline and after treatment, using Luminex 200™ system. We also found significantly higher baseline levels of IL-1β, IL-6 and TNFα in aged vs. young humans (P<0.001), as previously reported. Topical applications of the barrier repair emollient significantly enhanced epidermal permeability barrier function (P<0.01) and stratum corneum hydration (P<0.05). In parallel, circulating levels of IL-1β and IL-6 normalized, while TNFα levels declined substantially. The results of this preliminary study suggest that a larger clinical trial should be performed to confirm whether improving epidermal function also can reduce circulating pro-inflammatory cytokine levels in aged humans, while also possibly attenuating the downstream development of chronic inflammatory disorders in the aged humans.