Photosensitivity in cutaneous lupus erythematosus

Abstract

Background: Ultraviolet radiation (UVR) is a well-known exacerbating factor for cutaneous lupus erythematosus (CLE), with photosensitivity comprising one of the American College of Rheumatology (ACR) diagnostic criteria for systemic lupus erythematosus (SLE). However, discerning true photosensitivity in this population is difficult due to the broad language utilized by the ACR and the delayed-onset nature of photosensitive lupus lesions.

Aims: The objective of this report is to provide a review of photosensitivity, photoprovocation, and phototherapy in the context of CLE patients.

Methods: A literature review in PubMed was conducted using the terms 'ultraviolet light,' 'lupus erythematosus,' 'photoprovocation,' or 'photosensitivity.'

Results: Self-patient reporting of photosensitivity and the broad definition of photosensitivity have led to the wide range of photosensitivity rates in CLE patients. Photoprovocation testing provides a more objective method to measure photosensitivity, but even these trials demonstrate significant differences due to protocol variations. Despite UVR's deleterious effect on lupus patients, ultraviolet A (UVA)-1 may have therapeutic benefits as shown by observations on murine models and human lupus subjects.

Conclusions: Accurately discerning photosensitivity has diagnostic implications for SLE and provides motivation for greater patient adherence to photoprotective methods.

Figure 1

Mechanisms of UVA and UVB radiation in cutaneous lupus. UVA and UVB have both distinct and overlapping actions in cutaneous damage contributing to CLE lesion development. UVB has wide-ranging effects on both cellular signaling through cytokines and chemokines and direct cellular damage. UVA also causes direct DNA damage and induces apoptosis and impaired immune function through ROS generation. Abbreviations: ICAM – intracellular adhesion molecule; ROS – reactive oxygen species; UVA-ultraviolet-A; UVB – ultraviolet-B; UVR – ultraviolet radiation; VCAM – vascular cellular adhesion molecule