A Study to Document the Effect of Petrolatum on Innate Immune Responses in the Skin

Petrolatum is a very well-known emollient that has been used since the 1800's. Not only has it been used to help with dry skin, but it is also marketed as a substance that protects minor cuts and burns. In the past it was thought to be inferior to topical antibiotics in infection prevention for cutaneous wounds. However, in 1996 a large, multicenter trial including over 900 patients showed that petrolatum is as safe and effective as the topical antibiotic, bacitracin in preventing infections for patients undergoing dermatological surgery. In this trial, not only did the petrolatum group have similarly low rates of infection, this group also reported no cases of contact dermatitis. Aside from being more expensive than petrolatum, bacitracin and other topical antimicrobials (i.e. neomycin) have been known as common culprits of contact dermatitis. In a study done by the North American Contact Dermatitis Group between 2005-2006, 9.2 and 10% of the over 4,000 patients who were patch tested had an allergic reaction to either bacitracin or neomycin, respectively. For the above reasons, it is clear that petrolatum is an appealing alternative to topical antibiotics for infection prevention in patients undergoing dermatological procedures. This study however lacked any mechanistic analyses to provide molecular insight as to how petrolatum was effective at infection prevention. The aim of this research is to study the effect of petrolatum on innate immune reactions in the skin. In particular, petrolatum's effect on various antimicrobial peptides after contact with the skin for 3 days will be examined. This will be done through immunohistochemistry for various cellular infiltrates as well as mRNA gene expression via RT-PCR analysis for inflammatory and AMP genes. Tissue samples of petrolatum occluded skin will be compared to both healthy skin and skin under occlusion alone as controls. These comparisons will isolate the effect of the petrolatum on the skin.