RESUMO
Objective To investigate the effects of calcitonin gene-related peptide ( CGRP) on the inflammatory response induced by lipopolysaccharide ( LPS) of Klebsiella pneumoniae. Methods Klebsiella pneumoniae was cultured in vitro to extracted LPS. Different concentrations of LPS were used to stimulate BEAS-2B cells. The activation of human βdefensin 2 (hBD-2) in these cells was detected by immunofluo-rescence assay before and after adding different concentrations of CGRP. MTT assay and flow cytometry were respectively used to detect the proliferation and apoptosis of BEAS-2B cells after LPS stimulation with and without CGRP treatment. Neutrophil granules released in the cells after CGRP treatment were detected using neutrophil gelatinase-related apolipoprotein ( NGAL) as the marker. Results Immunofluorescence assay re-sults showed that LPS at different concentrations could significantly increase the relative expression of hBD-2 in BEAS-2B cells, which was significantly inhibit by CGRP intervention. LPS at 50 ng/ml, 100 ng/ml and 200 ng/ml had no significant effect on the activity of BEAS-2B cells, while treatment with 400 ng/ml of LPS for 24 h could significantly reduce the activity and promote the apoptosis of BEAS-2B cells. In addition, re-markedly increased cell activity and suppressed cell apoptosis were induced when BEAS-2B cells were trea-ted with 10 nmol/L of CGRP in combination with LPS. LPS at different concentrations could induce the re-lease of neutrophil-specific granules, while the LPS-induce release could be significantly inhibited by 10 nmol/L of CGRP. Conclusions CGRP could inhibit the expression of hBD-2, promote cell proliferation and reduce the degranulation of neutrophils to down-regulate the inflammatory response induced by LPS of Klebsiella pneumoniae.