Consideration of the Pathophysiology of Rosacea To Be Demodectic

[Guide]

An article on the pathophysiology of rosacea overlaps with demodectic rosacea and the phenotype classification. Below are the three highlights considered in the paper: 

(1) New hypotheses to explain how Demodex mites may control host immunity, by analogy with what happens in tumor pathology: inducing tolerogenic dendritic cells through their Tn Ag, and diverting the body's defence reaction by exploiting the immunosuppressive properties of VEGF; 

(2) Leading to consider rosacea not as a disease of the innate immunity, but as a chronicle infection by Demodex with T cell exhaustion;
Highlighting of the ambiguities of the current definition of rosacea of the NRS, and the overlap with demodicoses, suggesting that all these dermatoses are different phenotypes of the same disease;

(3) The suggestion, for the dermatologists, to learn to detect the demodicoses among the patients with persistent erythema, in the aim to treat at least these patients with topical acaricidal treatment.

The article concludes, "The interactions among VEGF, Demodex, and the immune system need further exploration and the nosology of rosacea would then need to be adapted accordingly. The effectiveness of treating any patient with ETR first with an acaricidal cream needs to be assessed in prospective controlled clinical trials with long-term follow-up. Currently, learning to distinguish patients with pityriasis folliculorum from those with isolated ETR is crucial so that they can be managed appropriately with an acaricidal cream." [1]

Another article explains it this way:

"According to dermatology literature, Demodex is found to colonize normal human skin everywhere; on an average, the Demodex population is approximately 5/cm2 of skin in the adult population. They usually do not result in any dermatological problems, but when the parasites penetrate the dermis, they can cause acne, rosacea, and folliculitis. The symptoms aggravate with an increase in their population. Rosacea is a disease of multifactorial origin, and the individual characteristics of the patient can modify the severity of the inflammatory response to Demodex. Finding large quantities of Demodex may play an important role in the pathogenesis of rosacea in addition to other trigger factors." [2]

End Notes

[1] Forton, F.M.N. The Pathogenic Role of Demodex Mites in Rosacea: A Potential Therapeutic Target Already in Erythematotelangiectatic Rosacea?. Dermatol Ther (Heidelb) (2020). https://doi.org/10.1007/s13555-020-00458-9

Image courtesy of Dermatology and Therapy

[2] Indian J Ophthalmol. 2018 Jan; 66(1): 36–38.
Demodex and rosacea: Is there a relationship?
Diana Gonzalez-Hinojosa, Alejandro Jaime-Villalonga, Gustavo Aguilar-Montes, and Lorena Lammoglia-Ordiales