Association between Serum Sialic Acid Levels and Disease Severity in Psoriasis: A Case-control Study

Abstract

Introduction: Psoriasis is a chronic inflammatory disease distributed worldwide with varying prevalence among different geographical areas and ethnic groups. It has been recently found that oxidative stress is one of the important factors in the pathogenesis of psoriasis. The varied effects of oxidative stress include changes in cellular uptake, altered enzymatic activity of proteins, increased predisposition to aggregation and proteolysis, which subsequently alter their immunogenicity. Sialic Acid (SA) is an acetylated derivative of neuramic acid. It is a marker for acute phase inflammatory response, with increased levels observed in inflammatory diseases. Aim: To estimate the levels of SA in psoriasis patients and to correlate with the severity of the disease. Materials and Methods: This case-control study was conducted among 50 patients, diagnosed with psoriasis, and 50 age and sex-matched subjects without psoriasis. General, systemic and dermatological examination was carried out. The severity of psoriasis was assessed according to Psoriasis Area Severity Index (PASI). The serum was treated with ethanol and centrifugation to precipitate proteins. The SA of both the precipitate and supernatant was estimated based on the reaction of SA with the ninhydrin reagent. Calculation of sialic acid was done by the formula: OD of test/OD of standard×concentration of the standard. To establish a correlation student’s t-test was used. Results: There were 39 males and 11 females in each case and control group. The mean±SD age of cases and controls was 44.04±10.9 years and 44.10±9.996, respectively. The mean PASI value was 23.1666±18.47. Mean SA in cases and controls were 35.792±2.124 and 28.556±3.854 (p-values <0.001). A positive correlation was observed between the free SA and psoriasis severity (p-value <0.001, r=0.460). Conclusion: Higher levels of free serum SA were significantly associated with more severe forms of psoriasis.

Keywords

• inflammatory disease
• immunogenicity
• psoriasis area severity index