Role of serum interleukin-19 (IL-19) levels in acne vulgaris: a comprehensive case control study

Acne vulgaris (AV) has a multifactorial pathogenesis, with inflammation being a key factor. The pro-inflammatory role of interleukin (IL)-19 has been explored in several systemic and some dermatological conditions. This study aimed to analyse serum levels of IL-19 in cases as well as healthy controls and to assess its correlation with the disease severity. A cross sectional, observational, analytical study was performed over a time period of 18 months at a tertiary care hospital. The study included 37 clinically diagnosed cases of acne aged between 16 to 30 years and 37 age and sex matched controls. Severity of the lesions was calculated using the Global Acne Grading System (GAGS). IL-19 levels of all the participants were measured with the help of quantitative Enzyme Linked Immunosorbent Assay (ELISA). The Spearman's rank correlation coefficient was used to evaluate the relationship between serum levels of IL-19 and the severity of AV, and a p-value of less than 0.05 was considered statistically significant. In this study, serum IL-19 levels showed a positive correlation with both the patients' age and the duration of their symptoms, with p values of 0.04 for each. The median serum IL-19 levels were observed to be higher in the cases (80.89 ng//L) as compared to controls (44.82 ng/L), although this difference was not statistically significant (p = 0.095). Additionally, no significant correlation was found between IL-19 levels and the severity of acne (p = 0.45). Unlike prior work, our study found no link between IL-19 and severity of AV. Thus, we conclude that IL-19 may not be a reliable marker of the disease severity as previously stated and further research, preferably in larger sample size is warranted to confirm the same.