Evaluation of plasma antimicrobial peptide LL-37 and nuclear factor-kappaB levels in stable chronic obstructive pulmonary disease.

Background: Antimicrobial peptides are effectors of host defence against infection and inflammation and can encourage wound repair.

Objectives: The objectives of this study were to investigate the plasma antimicrobial peptide LL-37 and nuclear factor-kappaB (NF-κB) levels in patients with stable COPD compared with a control group and to highlight their importance in immune inflammation.

Methods: One hundred and thirty-eight stable COPD patients and 33 control subjects were enrolled in the study. The COPD patients were classified into four groups based on FEV1 (groups I-IV) and also divided into "low-risk and high-risk" groups (groups A-B [low risk], C-D [high risk]).

Results: Plasma LL-37 levels were significantly lower while plasma NF-κB levels of the COPD patients were significantly higher than those of the control subjects ( P <0.001, both). LL-37 levels were significantly lower in group IV than in groups I, II, and III ( P <0.01, all). NF-κB levels were significantly higher in groups III and IV than in groups I and II ( P <0.05, both). There was a positive correlation between FEV1 and FEV1 /FVC in all COPD patients ( r =0.742, P <0.001) and in group D ( r =0.741, P <0.001). Furthermore, there was an inverse correlation between LL-37 and NF-κB in both the groups C ( r =-0.566, P <0.001) and D ( r =-0.694, P <0.001) and group C+D combined ( r =-0.593, P <0.001). Furthermore, in group C, LL-37 and FEV1 were positively correlated ( r =0.633, P <0.001).

Conclusion: Our study indicated that plasma LL-37 and NF-κB may play an important role in chronic immune inflammation. Decreased LL-37 levels may be particularly high risk for patients in stage IV disease. The role of LL-37 as a target for treatment of the immune system and COPD must be widely evaluated.