The theories of the cause of rosacea include a genetic component, something in our environment, the blood vessels themselves, or some sort of inflammatory response. Skin damage due to the sun’s rays is known to have an impact on rosacea.
The skin has an innate immune response in rosacea, since we do know that there are a lot of antimicrobial elements (known as cathelicidins). These cathelicidins are part of our defence against microbes, which leads researchers to believe that a microbe of some kind is present, causing the problem.
How does this work?
Cathelicidins encourage some white blood cells into the layers of skin that surround the blood vessels. Cathelicidins also promote the dilation (expansion) of blood vessels. These white blood vessels release a substance known as nitric acid, which also increases the size (dilation) of the blood vessels.
Fluid begins to leak out of these dilated blood vessels, which causes some swelling of the skin. The fluid fills in the gaps between the blood vessels and structures of the face. The element in our blood that causes inflammation is also leaked into our tissue, which causes more inflammation.
What about the hair follicle mites?
There is evidence that the hair follicles of rosacea may contain a higher concentration of Demodex folliculorum, a type of mite that lives in the pores of mammals. The role of the mites is unclear, however, since not everyone has the mites.
What about Helicobacter pylori?
There is an observed increase in rosacea in those with H. pylori, but most dermatologists are unclear as to the role of this bacteria.