Inflammatory skin conditions such as psoriasis have been successfully treated for decades with narrowband UVB radiation (NB-UVB). The prevalence of multiple sclerosis (MS) has shown latitude gradients with more disease at higher latitudes where there is less ambient UV radiation. In the PhoCIS trial (Phototherapy for Clinically Isolated Syndrome), participants with CIS, the earliest detectable form of multiple sclerosis (MS), were randomised into a treatment arm with exposure to suberythemal NB-UVB (311-312 nm) to the full body 3 times per week for 8 weeks, or to standard care. This phototherapy protocol is used frequently for patients with psoriasis. All participants were followed clinically and immunologically for 12 months. After 12 months, all the control participants had converted from CIS to MS. In contrast, 70% of those who received phototherapy had converted to MS, with 30% showing no new lesions after 12 months on magnetic resonance imaging.
We have used a biobank of frozen cells and sera from the participants to investigate the mechanisms by which NB-UVB may alter immune cell networks and alter MS progression. Alternatively, biomarkers associated with exposure of skin to NB-UVB may be uncovered. Both the proteome and the metabolome have been analysed in sera taken longitudinally from the participants receiving NB-UVB, compared with the control non-irradiated CIS participants. This has been complemented by studies of biomarkers in serum that have been clinically validated to give predictions of new lesions indicative of MS progression. These biomarkers have confirmed the clinical and radiological benefits of exposure to NB-UVB.
Suberythemal NB-UVB delivered to the skin caused significant changes to the cells, proteins and analytes in the blood, many lasting months. We propose these changes are important to an improved understanding of cell-cell communication and immunological networks associated with a disease such as MS.