Cynthia Zuccaro

The effects of burn blister fluid on keratinocyte replication and differentiation

The optimal clinical care of burn blisters has not been determined. The effects of burn blister fluid and control serum on epidermal cell proliferation and differentiation were determined. Both burn blister fluid and serum decreased the cell responses necessary for healing of the burn wound by approximately 40%. The degree of suppression varied from 81% to 28% dependency on the specific burn blister fluid and cell tested. These data suggest that reepithelialization may be inhibited beneath burn blisters. We conclude that in most cases burn blisters should be debrided.

Thermal injury induces expression of CD14 in human skin

BACKGROUND Skin is equipped with an array of immune mediators aimed at fighting invading microbes. CD14 has been shown to play a key role in modulating the activation of cells by LPS. Since LPS levels within burn wounds are often found to be elevated, we sought to examine the expression of CD14 within human skin following thermal injury. METHODS Patients who sustained partial thickness burns, were recruited into the study (n=57). Total RNA was isolated from both burn and normal (control) skin. Northern blot analysis and TaqMan RT-PCR were used to determine skin CD14 mRNA levels. Immunohistochemistry was used to localize CD14 expression in burned and normal skin. RESULTS Quantitative PCR showed significantly increased CD14 expression levels in the immediate post-burn period (P<0.05 burn versus non-burn). Immunohistochemistry revealed more pronounced CD14 staining 24 h after the injury, reaching normal levels approximately 5-7 days post-burn. CONCLUSION CD14 expression peaks within the first week post-burn before declining, reaching normal levels after 14 days. This loss of supranormal CD14 expression locally within the wound may contribute to a weakened host defense response 5-6 days after injury, when patients become especially vulnerable to infection.

The effect of essential fatty acid supplementation on keratinocyte replication

Epidermal cell growth in culture, using the low calcium, low serum technique described by Boyce, is thought to induce rapid expansion by inducing an essential fatty acid (EFA) deficiency state. To determine the mechanisms whereby EFA deficiency induces increased epidermal cell growth, keratinocytes were passaged into medium without or with the addition of EFAs, 18:2(n-6), 20:4(n-6). The resulting populations were assayed for replication rate, differentiation, and plating efficiency. Supplemental EFAs significantly decrease keratinocyte culture expansion. This is evidenced by an increase in generation time, a decrease in thymidine incorporation, and a decrease in modeled replication rate. EFA supplementation also increased the expression of cornified cell envelopes. Serum-free medium induces EFA deficient keratinocytes that demonstrate increased replication and decreased differentiation. Restoration of EFAs reverses these changes. It may be possible to manipulate keratinocyte physiology using fatty acid modifications.