Sunlight exposure worsens clinical symptoms in autoimmune diseases such as lupus

Researchers from the Division of Rheumatology and colleagues have demonstrated the previously not-understood mechanism in which UV light exposure in lupus patients leads to local inflammation of the skin and systemic inflammation of other organs including the kidneys.

Lupus, a systemic autoimmune disease in which the body’s immune system attacks its own tissues, affects over 300,000 people in the United States. While severity of disease varies, up to 80 percent of lupus patients experience exacerbation of their condition when exposed to UV light, resulting in skin inflammation and increased kidney damage.

Their paper, “Acute skin exposure to ultraviolet light triggers neutrophil-mediated kidney inflammation” was recently published in Proceedings of the National Academy of Sciences.

The team had previously determined that UV light exposure triggers increases in type I interferon, a protein secreted by infected cells, in the skin and kidneys of lupus patients. Skopelja-Gardner et al. have examined this incidence and shown that a type of white blood cells called neutrophils are responsible for transmitting inflammation from the exposure, through the skin and ultimately to the kidneys.

Neutrophils are the first cell type to respond to inflammation and are commonly linked to skin and kidney tissue injury in lupus patients.  When skin is exposed to UV light, researchers observed that neutrophils not only infiltrated the UV light-exposed skin, but also disseminated throughout the body and migrated to the kidney. Neutrophils are at least one responsible agent causing inflammatory and injury responses in the kidneys of lupus patients as a result of UV light.

Lead author Sladjana Skopelja-Gardner, PhD, is a senior fellow in the Division of Rheumatology and senior author Keith Elkon, MD, is a professor and head of the Division of Rheumatology.