The Correlation between Interleukin 33 and Psoriasis: A Systematic Review and Meta-Analysis

Psoriasis is a common genetic autoimmune disorder with a global prevalence of 2–3%. The clear pathogenesis of psoriasis is not fully understood, but hyperproliferation and inflammation of the epidermis with marked infiltration of immune cells have been indicated in psoriasis with such cells producing different types of cytokines- interleukin. As such a new member of the IL-1 cytokine family, in some research, IL-33 has been linked with psoriasis showing high serum concentration of IL-33 in human psoriatic plaques compared to normal healthy skin. Despite this, the association between IL-33 and psoriasis is not clear. Herein, in this review, we aim to investigate the correlation between serum IL-33 levels and psoriasis. We conducted meta-analysis using fixed or random-effects models to calculate pooled standard mean differences. We found that the mean IL-33 serum levels were reported between 0.35 pg/mL to 586 pg/mL in the psoriatic group and 0 pg/mL to 87.7 pg/mL in the healthy control group. Out of five, four individual studies included in the analysis reported statistically significant differences in IL-33 levels, the pooled estimate (SMD = 0.340 95% CI: −0.308 to 0.988), however, did not indicate a significant relation between IL-33 and psoriasis. This analysis revealed no significant difference between serum IL-33 levels in the psoriatic population in comparison to healthy controls. This may be because we did not include any animal studies, lab-based studies, any other markers mixed together, or any other cases of diseases mixed together. However, further research is warranted to confirm the reported association as this analysis is limited by the low-quality and observational nature of the included studies.