STATUS OF CATHELICIDIN LL-37, CYTOKINE TNF, AND VITAMIN D IN PATIENTS WITH PULMONARY TUBERCULOSIS

Development of Mycobacterium tuberculosis (Mtb) infection depends on the ability of the host to elicit the protective immune response to the pathogen. Cathelicidin plays a role in antibacterial innate immunity mechanisms. This peptide contributes to the barrier function of respiratory epithelium and takes part in controlling pulmonary bacterial infections. LL-37 (leucine-leucine-37) is involved in host defense and innate immune response to mycobacterial infections, as well. This study aims to evaluate the serum concentrations of LL-37 in individuals with active pulmonary tuberculosis (TB) and to determine whether any correlations between peptide LL-37, tumor necrosis factor (TNF) and vitamin D serum levels exist. A total of 46 adults with pulmonary TB were recruited for the study. Sixty-one controls were randomly selected as control group. Serum concentrations of cathelicidin LL-37, vitamin D (25(OH)D), as well as TNF, were measured using an enzyme-linked immunosorbent assay (ELISA) kit. The mean (+/- SEM) level of LL-37 was significantly higher in the TB group (7.45 +/- 1.58) compared with healthy controls (1.41 +/- 0.22) (p < 0.001). Mean serum concentration of TNF was significantly higher in the TB group (8.51 +/- 1.92) compared with healthy controls (2.69 +/- 0.19) (p < 0.001). There was no significant difference in mean serum levels of vitamin D between healthy (26.10 +/- 1.74) and TB subjects (24.18 +/- 1.95). No correlations between LL-37, TNF, and vitamin D levels in patients with TB were observed. Our results indicated that serum levels of peptide LL-37 during TB is raised significantly, and this observation is compatible with the general view of the important role of this cathelicidin in defense mechanisms against Mtb infection.