According to a study published in the Journal Modern Rheumatology, the serum calprotectin levels present as a promising biomarker to detect severity, risk, and treatment response of ankylosing spondylitis (AS).

The analysis involved 260 healthy controls (HCs) and 262 AS patients. The pharmaceutical therapy was given to 142 active AS patients and their clinical response was determined using ASAS 40 improvement criteria. The AS patients and HCs went through extraction of 4 mL blood sample during enrollment and 142 active AS patients at month 1, 3, 6 postoperatively.  Enzyme-linked immune sorbent assay (ELISA) was used to assess serum calprotectin, IL-17, TNF-α,  and IL-1β expressions.

AS patients exhibited greater expression of calprotectin as compared to HCs. The baseline calprotectin was noticed to be of great diagnostic value for AS as per Receiver Operating Curve (ROC) analysis. The VAS, BASFI, BASDAI, ESR, CRP and PGA showed a positive relationship with calprotectin level. The  IL-17, TNF-α,  and IL-1β also showed elevated expressions with higher calprotectin levels. Active AS patients showed significantly decreased calprotectin levels from the baseline to 1, 3 or 6 months after the treatment. Moreover, patients obtained ASAS 40 were the more significant calprotectin shift during the first month, and this shift could estimate patients achieving ASAS 40 with AUC of 0.691.