Specific Kidney Biomarker May Help Track Lupus Progression, Researchers Say

Measuring the levels of a protein called epidermal growth factor — a promising kidney biomarker — in patients with lupus may help distinguish patients with kidney involvement from those without, according to researchers at the University of Michigan.

Their findings were presented at the American Society of Nephrology’s Kidney Week 2016 meeting Nov. 15-20 in Chicago.

Systemic lupus erythematosus (SLE) — generally just called lupus — is an autoimmune disease that happens when the body’s immune system attacks its own tissues. Some symptoms include rash, joint pain, and fatigue. When lupus attacks the kidneys, the damage can be life-threatening. Now, researchers investigated whether kidney biomarkers would signal lupus progression and signs of complications.

“Lupus patients have a high risk of kidney involvement, which can lead to end-stage renal disease requiring dialysis or transplant,” Emily Somers, PhD, ScM, associate professor of internal medicine (rheumatology), environmental health sciences, and obstetrics and gynecology at U-M and a member of the U-M Institute for Healthcare Policy and Innovation, said in a news release. “In addition, there is a great need for biomarkers to detect early kidney involvement and to monitor progression.”

Somers is a leading researcher in the lupus field and the director of the Michigan Lupus Epidemiology & Surveillance (MILES) Program Cohort and Biobank, which collects data and biospecimens that will allow for comprehensive investigations related to risk factors for lupus onset, progression, and comorbidities.

“Lupus is a disease that predominantly affects women, often striking at the prime of life,” Somers said. “Through the MILES Program, we previously showed that for black women, who are disproportionately affected by lupus, their risk of lupus is highest in their 20s. Forty percent of black females with lupus have kidney involvement, and 15 percent have end-stage renal disease.”

In the new study, Somers and colleagues measured the epidermal growth factor (EGF) protein in the urine of 394 patients with lupus. This protein, which can be found in urine, saliva, milk, and plasma, has been found to be a promising, noninvasive biomarker of kidney disease progression.

The researchers found that the levels of EGF improved the ability to differentiate patients with lupus and kidney involvement from those without. The protein was seen to overcome the ability of standardly used markers in assessing kidney damage, such as protein-to-creatinine ratio.

The researchers also discovered that urinary EGF was associated with a global score representing lupus damage accumulated across all organ systems, whereas standard markers were not, suggesting that the protein might also play a role in overall lupus outcomes.

“Validating this biomarker as a way to monitor lupus severity and progression is an exciting step in piecing together the complexity of lupus,” Somers said. “Ultimately we aim to enhance our ability to identify and treat those affected sooner, before the disease has caused even more complications.”