Anti-inflammatory effects of secondary metabolites of marine Pseudomonas sp. in human neutrophils are through inhibiting P38 MAPK, JNK, and calcium pathways.

Shun-Chin Yang,Chun-Yu Chen,Ping-Jyun Sung,Chun-Yu Chen,Jimmy Kuo,Tsong-Long Hwang,Chwan-Fwu Lin

doi:10.1371/journal.pone.0114761

Abstract

Activated neutrophils play a significant role in the pathogenesis of many inflammatory diseases. The metabolites of marine microorganisms are increasingly employed as sources for developing new drugs; however, very few marine drugs have been studied in human neutrophils. Herein, we showed that secondary metabolites of marine Pseudomonas sp. (N11) significantly inhibited superoxide anion generation and elastase release in formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP)-activated human neutrophils, with IC50 values of 0.67±0.38 µg/ml and 0.84±0.12 µg/ml, respectively. In cell-free systems, neither superoxide anion-scavenging effect nor inhibition of elastase activity was associated with the suppressive effects of N11. N11 inhibited the phosphorylation of p38 MAP kinase and JNK, but not Erk and Akt, in FMLP-induced human neutrophils. Also, N11 dose-dependently attenuated the transient elevation of intracellular calcium concentration in activated neutrophils. In contrast, N11 failed to alter phorbol myristate acetate-induced superoxide anion generation, and the inhibitory effects of N11 were not reversed by protein kinase A inhibitor. In conclusion, the anti-inflammatory effects of N11 on superoxide anion generation and elastase release in activated human neutrophils are through inhibiting p38 MAP kinase, JNK, and calcium pathways. Our results suggest that N11 has the potential to be developed to treat neutrophil-mediated inflammatory diseases.

Highlights

Neutrophils are major cells that induce innate immune responses and they act as components of cellular inflammatory reactions [1]
The fingerprint chromatogram of N11 was obtained by high performance liquid chromatography (HPLC) for quality control of the ethyl acetate extraction of secondary metabolites of marine Pseudomonas sp
N11 failed to affect superoxide anion generation in PMA, a protein kinase C (PKC) activator, stimulated human neutrophils (Figure 2B), suggesting that the inhibitory effect of N11 on superoxide anion generation is mediated by a PKC-independent pathway

Summary

Introduction

Neutrophils are major cells that induce innate immune responses and they act as components of cellular inflammatory reactions [1]. Growing evidence has suggested that overwhelming activation of neutrophils is harmful to human health. Emerging evidence has suggested that inhibition of activation of human neutrophils is a viable therapeutic strategy for the treatment of organ injuries and inflammatory diseases [6, 7]. Recent research has demonstrated that MAP kinases are potential therapeutic targets for the treatment of inflammatory diseases [9]. The inhibitors of p38 MAP kinase are able to prevent the progression of collageninduced arthritis, inflammatory bowel disease, and chronic obstructive pulmonary disease [10, 11, 12]. The undesired side effects of these inhibitors limited their clinical development and other potent compounds remained to be explored

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Discussion

Conclusion