BACKGROUND: Initial assessment of patients with ulcerative colitis (UC) is challenging and relies on apparent clinical symptoms and measurements of surrogate markers (e.g., C-reactive protein [CRP] or similar acute phase proteins). As CRP only reliably identifies patients with severe disease, novel biomarkers are currently needed for identification of patients with mild or moderate disease activity. Using a commercially available platform, we aimed at identifying serum biomarkers that are able to grade the disease severity.

METHODS: Serum samples from 65 patients with UC with varying disease activity (Mayo score) and from 40 healthy controls were analyzed by multiplex enzyme-linked immunosorbent assay for 78 potential disease biomarkers. Using the statistical software SIMCA-P+ and GraphPad Prism, multivariate statistical analyses were conducted to identify a limited number of biomarkers to assess disease severity.

RESULTS: Alpha-1 antitrypsin (AAT) differentiated between mild and moderate UC (area under the curve [AUC] = 0.79) with a sensitivity of 0.90 and a specificity of 0.70, thereby exceeding the predictive ability of CRP (AUC = 0.52). Combining alpha-1 antitrypsin and granulocyte colony-stimulating factor produced a predictive model with an AUC of 0.72 when differentiating mild and moderate UC, and an AUC of 0.96 when differentiating moderate and severe UC, the latter being as reliable as CRP.

CONCLUSIONS: Alpha-1 antitrypsin is identified as a potential serum biomarker of mild-to-moderate disease activity in UC. With the ability to differentiate between mild, moderate, and severe stages of UC using a simple serum biomarker that is already commercially available, clinicians can initiate individualized treatment regimens at an earlier stage before endoscopic examinations are available.