Scientists report on the development of candidate blood biomarkers for diagnosing systemic lupus erythematosus (SLE) and systemic sclerosis (SSc). The team at Lund University in Sweden used recombinant antibody microarrays to identify immunoregulatory protein expression profiles that differentiated between the two autoimmune diseases and indicated disease severity and activity. Their research is published in Molecular & Cellular Proteomics in a paper titled “Serum Protein Profiling of Systemic Lupus Erythematosus and Systemic Sclerosis Using Recombinant Antibody Microarrays.”
There are currently no specific biomarkers for diagnosing SLE or predicting SLE flares, and no single clinical test can diagnose the condition, report Christer Wingren, Ph.D., and colleagues. Moreover, traditional proteomics techniques including 2-D gels and mass spectrometry have been unable to identify serum, plasma, or urinary protein signatures. Dr. Wingren’s team has taken a different approach to identifying biomarkers for SLE and SSc, by using a recombinant antibody microarray setup to profile the serum proteome of the diseases. They focused primarily on immunoregulatory proteins in crude, directly biotinylated sera.
Using this approach, the researchers identified panels of biomarkers, including cytokines and complement proteins, which essentially diagnosed SLE and SSc, distinguished between the two diseases, and reflected disease severity or activity. Some of the markers had previously been linked with SLE, but there were a number of new markers, they report. In the majority of cases, the expression signatures were better at classifying the severity of disease than conventional clinical parameters, the authors claim. The signature identified for lupus nephritis, the most severe form of SLE, in particular, had a sensitivity of 100% and specificity of 93%, respectively. Panels of differentially expressed analytes including complement proteins, interleukins, and interferon-gamma, in addition accurately predicted low, medium, and high disease activity.
The Lund University scientists claim the results will help shed new light on the molecular basis of SLE and SSc. They also aim to validate the potential use of their biomarker panels in larger prospective studies.