CRP and ankylosing spondylitis: Catestatin has been recognized for its immunomodulatory and metabolic regulatory functions in inflammatory diseases.13 Catestatin has been shown to exert anti-inflammatory effects by downregulating pro-inflammatory cytokines such as TNF-α and IL-6,14 both of which play critical roles in the pathogenesis of ankylosing spondylitis (AS).15 It was found that CST levels were significantly lower in AS patients compared to the control group and exhibited a negative correlation with the ASDAS-CRP, suggesting an inverse relationship between CST and disease activity.