A new collaborative study reveals unexpected insights into how skin is exposed to ultraviolet (UV) rays, which may exacerbate clinical symptoms in autoimmune diseases such as lupus.
Lupus, an autoimmune disease that can cause inflammation of the joints, skin, kidneys, blood cells, brain, heart and lungs, occurs when the immune system attacks its own tissues.
Previous research has proven that in up to 80% of lupus patients, exposure to sunlight can lead to local dermatitis and systemic flushes, including kidney disease. However, little has been understood about the basic mechanisms driving this process.
To determine how UV rays cause inflammation in the kidneys, the research team from the Geisel School of Medicine at Dartmouth and University of Washington (UW) investigated the role of neutrophils, a type of white blood cell found in abundance in the body that acts as a first responder to any type of inflammation. It has been associated with injury to the skin and kidney tissue in lupus patients.
In the study, the researchers looked for markers of inflammation and injury in the skin, blood and kidneys at different time points after exposure to UV rays in mice. And they were able to prove that the neutrophils not only infiltrate the skin exposed to UV rays, but also spread throughout the circulatory system and travel to the kidneys.
Dr Saladjana Scobelia Gardner, Associate Professor of Medicine at Geisel, said: “Interestingly, one subset of these neutrophils, the ones that we think are the most harmful, first moved into the skin that was exposed to UV light and then turned around and went to college. Somewhat unusual, we usually think of neutrophils as short-lived cells that kind of enlarge to where inflammation is and then die there. “
The researchers found that single exposure of the skin to UV rays stimulated inflammatory and injury processes in the kidneys, including transient proteinuria, even in healthy and normal mice.
“To be clear, normal, healthy mice don’t get the clinical type of kidney disease that you see in lupus patients. They get what we call subclinical injury, which means that there is an inflammatory process and an injury that occurs in the kidneys that cannot be seen through pathology,” Scopelja Gardner explains. Or looking at the tissue itself. The mice recover and are fine after that. “
“However, this subclinical infection (without symptoms) may have pathological consequences in the weak environment of pre-existing inflammation in lupus patients, and lead to flare-ups of kidney disease after exposure to sunlight,” she adds.
Importantly, the markers of inflammation and injury that they detected in the kidneys of the mouse after exposure to UV rays were very similar to the signs of kidney injury associated with severe kidney damage in lupus patients. In addition, exposure to ultraviolet light also resulted in an immune response that is often expressed in most lupus patients, the type 1 response to interferon, in both the skin and the kidneys.
Scobelia Gardner continued: “In general, I think what our research shows is that exposure of the skin to UV rays can be a source of inflammatory pathways related to lupus, and that neutrophils play an important role as a pathogen in this process, which contributes to kidney damage.”
Source: Science Daily