Recombinant Human Brain Natriuretic Peptide Attenuates LPS-induced Cellular Injury in Human Fetal Lung Fibroblasts Via Inhibiting MAPK and NF-κB Pathway Activation.

Inflammatory responses are vital in lung injury diseases, particularly acute respiratory distress syndrome (ARDS). Recombinant human brain natriuretic peptide (rhBNP) has been shown to exhibit anti-inflammatory effects in vivo in our previous studies. The present study aimed to investigate the mechanisms underlying the anti-inflammatory effects of rhBNP on lipopolysaccharide (LPS)-induced human fetal lung fibroblasts (HFL-1). The results showed that LPS induced a significant increase in the leakage of lactate dehydrogenase and the secretion of interleukin (IL)-1 beta. Activation of p38, extracellular-signal regulated kinase (ERK) 1/2, c-Jun NH2-terminal kinase (JNK) mitogen-activated protein kinases (MAPK)s, and nuclear factor (NF)-kappa B in HFL-1 cells was also observed following treatment with LPS. Treatment with rhBNP (0.1 mu M) reduced the production of IL-1 beta at the protein and mRNA levels. Moreover, rhBNP decreased the phosphorylation of p38, ERK1/2 and JNK induced by LPS. However, the JNK inhibitor, SP600125, significantly inhibited LPS-induced IL-1 beta production. These results indicate that the inhibition of IL-1 beta by may dependent upon the JNK signaling pathway. The LPS-induced NF-kappa B activation was also suppressed by rhBNP, and IL-1 beta production was inhibited by the NF-kappa B inhibitor. Furthermore, NF-kappa B activation was attenuated by the JNK inhibitor, indicating that NF-kappa B activation was dependent on the JNK signaling pathway. The present study suggests that rhBNP exhibits an anti-inflammatory effect on LPS-induced HFL-1 cell injury via the inhibition of MAPK and NF-kappa B signaling pathways and may exhibit therapeutic potential for acute lung injury and ARDS.