A Surprising Collaboration

What am I looking at?

This image shows a wound on the skin of a mouse during the healing process. The wound is the dark hole in the middle of the image (1). The immune cells are blue (2), and a kind of common skin bacterium called Staphylococcus epidermidis is shown in green (3). The white and red strands around the wound are hair on the mouse’s skin (4).

Biology in the background

You may have heard of humans’ gut microbiome, which helps us digest our food, but humans also have a beneficial microbiome on our skin. Staphylococcus epidermidis bacteria are part of this skin microbiome; they help protect our skin from other harmful microbes, producing compounds called ceramides that support the skin’s defenses against pathogens.

During wound healing, these bacteria work in concert with the cells of the immune system to fight off harmful microbes that could cause an infection. They amplify our innate immune response – the body’s first line of defense against pathogens – and they can even activate a specific type of skin cell called a keratinocyte to fight pathogens.

Although individual Staphylococcus epidermidis bacteria can’t be seen in this image, a single bacterium averages about 1 micrometer in diameter, or roughly 75 times smaller than the width of a human hair.

Technique

This image was created using confocal microscopy.