Calcitonin gene-related peptide inhibits interleukin-1beta-induced interleukin-8 secretion in human type II alveolar epithelial cells.
OBJECTIVE
Our previous data have shown that type II alveolar epithelial (AEII) cells express neuropeptide calcitonin gene-related peptide (CGRP), and that pro-inflammatory factor interleukin1-beta (IL-1beta) induces CGRP secretion in the A549 human AEII cell line. In the present study, we investigated the effect of endogenous and exogenous CGRP on IL-1beta-induced chemokine interleukin-8 (IL-8) secretion.


METHODS
We used enzyme-linked immunosorbent assay (ELISA) and RT-PCR to detect IL-8 protein and mRNA levels, respectively. siRNA and the stably transfected cell line were used to knock down and overexpress the CGRP gene, respectively, and chemiluminescence assay was used to detect reactive oxygen species (ROS) formation.


RESULTS
CGRP-1 receptor antagonist hCGRP8-37 (0.1-1 nmol/L) greatly amplified IL-1beta-induced IL-8 production. The inhibition of CGRP expression by siRNA significantly increased IL-8 secretion upon IL-1beta stimulation. However, cell clones stably transfected with CGRP showed significantly inhibited mRNA and protein levels of IL-8 induced by IL-1beta.


CONCLUSIONS
These data imply that AEII cell-derived CGRP suppress IL-1beta-induced IL-8 secretion in an autocrine/paracrine mode. Further investigation showed that CGRP attenuated IL-1beta-aroused ROS formation, which is an early indication of pro-inflammatory factor signaling.
Li
Wen-jing
WJ
Department of Physiology, School of Basic Medical Sciences, Peking University, Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing 100083, China.
Wang
Teng-ke
TK
D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism / Q000494:pharmacology*; D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D045744:Cell Line, Tumor; D018076:DNA, Complementary / Q000235:genetics; D004847:Epithelial Cells / Q000378:metabolism / Q000473:pathology; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology; D010446:Peptide Fragments / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D014162:Transfection
D000077221:Calcitonin Gene-Related Peptide Receptor Antagonists; D018076:DNA, Complementary; D053583:Interleukin-1beta; D016209:Interleukin-8; D010446:Peptide Fragments; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; C058636:calcitonin gene-related peptide (8-37); D015740:Calcitonin Gene-Related Peptide