Bone Protein Found to Reflect Lupus Disease Activity and Renal Involvement
Osteopontin (OPN) is a protein present in the bone and other tissues. Elevated levels of OPN have been observed in several autoimmune diseases including lupus. Investigators from a group called Systemic Lupus International Collaborating Clinics (SLICC) examined data from 344 people with lupus over the course of five years to determine whether raised OPN is a reliable biomarker for lupus. Specifically, they wanted to know if increased levels of OPN could predict damage; reflect current disease activity; or if increased OPN levels are associated with certain disease phenotypes (characteristics).
“We continuously search for biomarkers that can guide us towards a personalized medicine approach for each patient. To identify patients who are prone to develop damage early is important since these individuals may need even more careful monitoring,” says Christopher Sjöwall, Associate Professor at Linköping University in Sweden, responsible for the new study. “The research confirmed associations of OPN with disease activity and renal involvement, but the results regarding damage prediction were not in line with a previous smaller study.”
At baseline, circulating levels of OPN were markedly higher in patients with SLE, with men displaying higher levels compared to women. Clear differences in OPN levels were identified between patients of white race/ethnicity compared to non-whites. After 3-5 years, the researchers did not find statistically significant evidence of OPN levels predicting damage accrual. However, they did discover that OPN levels reflect disease activity and renal involvement (lupus nephritis) at baseline and over time.