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

Overview

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.

Petrolatum (also commonly called Vaseline) is a very well known moisturizer 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. It is widely used by Dermatologists as a substance to apply to wounds from cutaneous surgical procedures. In a large study, petrolatum was shown to be as effective as one of the major topical antibiotics to help prevent infection in patients who underwent dermatologic procedures. Not only are the other topical antibiotics expensive, but also they are commonly the cause of an allergic reaction in up to 10% of the population. Until now, no reason has been found to explain why petrolatum is effective in infection prevention. In a recent study, skin biopsies of skin that had petrolatum applied to them were obtained. Upon analysis certain "antimicrobial peptides" (peptides that possess anti-bacterial properties that help fight infection) have been found to be elevated. This could provide an answer as to why petrolatum was as effective as the topical antibiotic in the study mentioned above. This study hopes to improve our understanding of how the immune system acts and how the skin responds to petrolatum. In order to reach this goal, normal volunteers, will be patch tested with petrolatum. Then, biopsies will be taken of the skin at the sites where petrolatum was. Also, small biopsies will be taken from an area that received a patch but no petrolatum and an area that did not receive a patch to serve as controls. The biopsied skin samples will then be studied in a laboratory by methods such as immunohistochemistry and RT-PCR analysis, which will help define the response of the immune system to petrolatum. The rationale for the study is to better define petrolatum's effects in skin and how it is effective at preventing infections.