Skin Barrier Function and Inflammation in Aging: The BIA Study

This is a randomized, investigator-blinded, self-controlled pilot study of the physiologic response to topical moisturizers among older adults with dry skin. The overarching hypothesis is that skin barrier decline is an important source of chronic inflammation, and that skin barrier restoration with moisturizers can reduce serum biomarkers of inflammation. The primary objective is to determine the feasibility for a larger trial, and the secondary objectives are to determine the extent to which measures of serum inflammation, skin barrier function, and the skin microbiome change in response to moisturizers. Participants will be asked to apply one of two topical moisturizers that are widely available over the counter in the US (Vaseline® 100% pure petroleum jelly or CeraVe® moisturizing cream) once daily for 4 weeks to the front of the torso, buttocks, arms, and legs. Subjects will act as their own control (i.e. they will be asked to apply the study moisturizer they are randomized to for one intervention period (4 weeks) and not to apply topical moisturizers for the other 4- week intervention period). Participants will be randomized in a 1:1:1:1 ratio to one of 4 treatment groups: i. no intervention then CeraVe; ii. CeraVe then no intervention; iii. no intervention then Vaseline; iv. Vaseline then no intervention. At each visit (baseline, week 4, and week 8), participants will undergo skin barrier testing, skin microbiome sampling, and phlebotomy to measure serum inflammatory markers.

In older adults, inflammation is associated with geriatric conditions, including multimorbidity and frailty, that result in premature death. This phenomenon has been termed 'inflammaging,' and multiple potential mechanisms have been identified, including chronic infections, visceral obesity, increased gut permeability, and cellular senescence, among others.1,2 Limited data suggest that age-associated barrier decline in the skin may also play an important role. Beginning at about age 50, skin barrier decline is caused by decreased Na+/H+ antiporter activity and impaired stratum corneum acidification.3 Persons \>70 years of age also suffer from additional defects in cutaneous lipid production.4 The result is reduced resilience to minor injury and epidermal cytokine generation, which may have significant systemic effects, given that the skin is the body's largest organ.5 Additionally, changes in the skin barrier may result in dysbiosis and increased exposure to microbial products, as has been seen in age-associated gut barrier decline.6 Skin barrier decline has been directly correlated with levels of keratinocyte-derived inflammatory markers in aged mice.7 Furthermore, there is experimental evidence that application of moisturizers to aged skin may improve skin barrier function and reduce inflammation. In aged mice, application of petrolatum twice daily for 10 days significantly reduced cutaneous and serum inflammatory cytokines including TNFalpha, IL-1alpha, IL-1beta, and IL-6 after minor injury.7 The investigators propose a randomized, investigator-blinded, self-controlled pilot study of the physiologic response to topical moisturizers among older adults with dry skin. The overarching hypothesis is that skin barrier restoration with moisturizers can reduce serum biomarkers of inflammation. The primary objective is to determine the feasibility for a larger trial, and the secondary objectives are to determine the extent to which measures of serum inflammation, skin barrier function, and the skin microbiome change in response to moisturizers. Participants will be asked to apply one of two topical moisturizers that are widely available over the counter in the US (Vaseline® 100% pure petroleum jelly or CeraVe® moisturizing cream) once daily for 4 weeks to the front of the torso, buttocks, arms, and legs. Subjects will act as their own control (i.e. they will be asked to apply the study moisturizer they are randomized to for one intervention period (4 weeks) and not to apply topical moisturizers for the other 4- week intervention period). Participants will be randomized in a 1:1:1:1 ratio to one of 4 treatment groups: placebo i. no intervention then CeraVe; ii. CeraVe then no intervention; iii. no intervention then Vaseline; iv. Vaseline then no intervention. At each visit (baseline, week 4, and week 8), participants will undergo skin barrier testing, skin microbiome sampling, and phlebotomy to measure serum inflammatory markers.