Cathelicidin Antimicrobial Peptide (CAMP) and Its Correlation with Serum 25 Hydroxy Vitamin D in Under-Five Children with Pneumonia

Abstract Cathelicidins are human peptides involved in innate immunity, and are believed to be mediators of vitamin D-related immune benefits. We aimed to evaluate the correlation between serum levels of 25 hydroxy vitamin D (25(OH)D) and serum cathelicidin antimicrobial peptide (CAMP) in children hospitalized with severe pneumonia. This was a secondary analysis from a larger randomized double-blind placebo-controlled trial on vitamin D supplementation in severe pneumonia. Children aged 6 months to 5 years with the World Health Organization (WHO) defined severe pneumonia were included. Any child with rickets, immunodeficiency, or chronic illness was excluded. Baseline serum CAMP, serum 25(OH)D, and immunoglobulins were measured and analyzed. A total of 163 under-five children were recruited with mean (standard deviation) age 16.4 (13.0) months. The median (interquartile range [IQR]) serum CAMP was 12.5(8.0–20.0) ng/mL and serum 25(OH)D was 14.4 (8.4–24.2) ng/mL. There was no significant correlation between serum cathelicidin and serum 25(OH)D ( r  = −0.064, p  = 0.415). Serum 25(OH)D was low (<20 ng/mL) in 105(64.4%) participants. Median (IQR) serum CAMP was comparable between children with low (<20 ng/mL) and normal serum 25(OH)D levels (13.0 [8.2, 22.1] and 12.0 [8.0, 17.4] pg/mL; p  = 0.2). Serum cathelicidin showed significant positive correlation with serum immunoglobulin M levels ( r = 0.456, p  < 0.001). There was no significant correlation between serum cathelicidin and serum vitamin D in under-five children hospitalized with severe pneumonia.