Science of the Skin

From the Summer 2018 edition of Vanderbilt Medicine Magazine

How the skin protects

Epidermis, the outermost layer of the skin, provides the critical protective barrier needed for terrestrial life. The process of epidermal barrier formation includes conversion of the essential fatty acid linoleate into skin-relevant oxidized lipids.

Two lipoxygenase enzymes, 12R– LOX and eLOX3, initiate this conversion pathway. An inactivating mutation in either enzyme leads to trans-epidermal water loss and the fish-skin symptoms of congenital ichthyosis. But how this oxidation pathway is completed was not clear.

In a study published in the Journal of Lipid Research, researchers evaluated candidate epoxide hydrolase enzymes that could participate in this conversion. They found that the enzymes EPHX2 and EPHX3 produce the end products of the 12R-LOX pathway in the epidermis, implicating their role in the formation of the mammalian water permeability barrier.

This work not only extends the basic understanding of a vital process for mammalian survival, it suggests a possible avenue for improving treatment of common skin barrier conditions such as atopic dermatitis.

 

Study tracks skin salt’s role in blood pressure control

In findings published in the Journal of Clinical Investigation, investigators use genetic and molecular approaches in mice to demonstrate that salt metabolism in the skin is important for systemic blood pressure control.

In mice fed a high-salt diet, large amounts of salt accumulate in the skin. Immune system cells (mononuclear phagocyte system, MPS) sense the sodium accumulation and activate a protein called TONEBP. This protein increases expression of the growth factor VEGFC by immune cells, which builds cutaneous lymph vessel capacity and enhances sodium and chloride clearance.

The study shows that elimination of the TONEBP gene in MPS cells prevented the VEGFC response to a high-salt diet and increased blood pressure. Likewise, blocking signaling through the lymph vessel VEGFC receptor inhibited the changes in lymph vessel density and resulted in salt-sensitive hypertension.

The findings support the idea that the immune and lymphatic systems in the skin work together to regulate electrolyte (sodium, chloride) composition and blood pressure. Defects in this regulatory system may be associated with salt-sensitive hypertension, researchers said.

 

New approach for staph-related skin abscesses explored

New multicenter research that includes Vanderbilt University Medical Center investigators could change treatment approaches to simple skin abscesses, infections often caused by Staphylococcus aureus (staph) bacteria.

The study, published in the New England Journal of Medicine, shows that adults and children who have simple abscesses 5 centimeters or smaller in diameter have higher cure rates if the abscess is drained in combination with antibiotic treatment, either trimethoprim-sulfamethoxazole (TMP/SMX or Bactrim) or clindamycin, compared to drainage alone.