Environmental Factors Tied to Lupus

Key points
• Ultraviolet light may cause flare-ups in systemic lupus erythematosus (SLE).
• The chemicals found in cigarette smoke can worsen the symptoms of SLE.
• Estrogen analogues such as oral contraceptives and bisphenol A (BPA), a substance used to make plastic bottles, may increase the risk of SLE.

Background
SLE affects women and African Americans disproportionately. Dr. Gaurav Gulati at the University of Cincinnati in Ohio points out that even though we have treatments for lupus, a complete understanding of its etiology and progression is lacking.

Although genetics clearly plays a role in SLE, it appears that environmental factors may act as triggers in those who are susceptible. Dr. Gulati conducted a review of the literature related to SLE and environmental versus genetic factors; he presented his findings recently in Seminars in Arthritis and Rheumatism.

The study
A systematic review was conducted that looked at over 100 studies focused on SLE.

The results
• A triad of factors was found in one study that linked a patient’s genetics, how the patient’s DNA changes over time, and exposure to environmental factors to the development and course of SLE.

• Twin studies reveal only a 24% concordance of SLE in identical siblings; this points to a conclusion that a combination of genetic predisposition and environmental factors is involved in the development of lupus.

• Heavy metals and other trace elements may be triggers for SLE; uranium, lead, and cadmium are linked to autoimmunity.

• Elements such as mercury, nickel, and gold have been implicated in delayed hypersensitivity and inflammation, and a higher rate of lupus has been noted among dental workers.

• An increase in SLE has been found in women who take oral contraceptives and in those exposed to xenoestrogens such as BPA, a chemical found in plastics.

Implications for physicians
• Physicians and particularly rheumatologists who treat patients with SLE should vigorously encourage positive lifestyle modifications such as smoking cessation and avoidance of direct sunlight.

• Patients with SLE should be advised to always wear sunscreen.

• Rheumatologists should provide regular surveillance to their patients with SLE as changes in disease activity and treatment are warranted.

References:

Gulati G, Brunner HI. Environmental triggers in systemic lupus erythematosus. Semin Arthritis Rheum. 2017 Oct 5. pii: S0049-0172(17)30469-9. doi: 10.1016/j.semarthrit.2017.10.001. [Epub ahead of print]