Multiple sclerosis: the surprising “drug-like” activity of sunscreens

Sclerosi multipla_

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system, affecting 2.5 million people worldwide. In 1974, Agranoff and Goldberg observed that the incidence of MS is inversely related to sun exposure in both hemispheres. Since vitamin D is synthesized from ultraviolet (UV) radiation on the 7-dehydrocholesterol present in the skin, Goldberg suggested that increased vitamin D production caused by exposure to sunlight could be responsible for reducing the incidence of MS. More recent results have made this hypothesis unlikely, however, and narrowband radiation (NBUVB) at 300-315nm has been shown to suppress the experimental model of MS (EAE). This narrow band produces little vitamin D from 7-dehydrocholesterol because it does not increase the levels of 25-hydroxycholecalciferol in the blood.

During the course of their studies, a team from the Department of Biochemistry of the University of Wisconsin-Madison, Madison, studied commercial sunscreen preparations to prevent the suppression of EAE by narrowband UVB. Quite unexpectedly, some solar filter preparations have completely suppressed the EAE without the aid of UV rays. The local application of Coppertone Spray sunscreen completely suppressed the development of lesions. When the mice were treated with NBUVB, the severity of the average disease had drastically decreased. Surprisingly, topical administration of the same sunscreen completely blocked the EAE. Therefore, the researchers focused on the components of active sunscreen preparations. The suppression of EAE by the sun preparations has been traced back to two esters of salicylate, homosalate and octasalate.

These compounds are not likely to work by blocking or absorbing UV light. Simply maintaining mice in complete absence of light did not affect the development of EAE. In addition, some more powerful sunscreens such as avobenzone and oxybenzone do not suppress EAE. Only the filters containing salicylate esters are effective and the salicylates themselves clearly block the EAE. Salicylates are known non-steroidal anti-inflammatory drugs (NSAIDs). However, a previous study revealed that acetylsalicylic acid had no effect on MS. Since NSAIDs are well known inhibitors of cyclooxygenase, mostly the isoform 2, and COX-2 has been observed in MS lesions, a possible mechanism of action of salicylates is the suppression of COX. COX inhibitors suppress EAE, but if salicylates suppress EAE by inhibiting COX it is not yet known. This is what he intends to discover the team with the upcoming experiments already planned.

  • Edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.

Scientific references

Wang Y et al. (2017) P.N.A.S. USA 114(32):8528-31.

Tsau S et al. (2015) BMC Medicine 13:153–169.

Wang Y, et al. (2013) Arch Biochem Biophys. 536:81–86.

Becklund BR et al. (2010) P.N.A.S. USA 107:6418–6423.

Rose JW et al. (2004) J Neuroimmunol 149:40–49.

Informazioni su Dott. Gianfrancesco Cormaci 1561 Articoli
- Laurea in Medicina e Chirurgia nel 1998 (MD Degree in 1998) - Specialista in Biochimica Clinica nel 2002 (Clinical Biochemistry specialty in 2002) - Dottorato in Neurobiologia nel 2006 (Neurobiology PhD in 2006) - Ha soggiornato negli Stati Uniti, Baltimora (MD) come ricercatore alle dipendenze del National Institute on Drug Abuse (NIDA/NIH) e poi alla Johns Hopkins University, dal 2004 al 2008. - Dal 2009 si occupa di Medicina personalizzata. - Detentore di un brevetto sulla preparazione di prodotti gluten-free a partire da regolare farina di frumento immunologicamente neutralizzata (owner of a patent concerning the production of bakery gluten-free products, starting from regular wheat flour). - Autore di un libro riguardante la salute e l'alimentazione, con approfondimenti su come questa condizioni tutti i sistemi corporei. - Autore di articoli su informazione medica, salute e benessere sui siti web salutesicilia.com e medicomunicare.it