| Summary: | 碩士 === 長庚大學 === 天然藥物研究所 === 93 === Abstract
Reactive oxygen species and granule proteases produced by neutrophils contribute to the pathogenesis of inflammatory diseases. In this study, a cellular model in isolated human neutrophils, which are important in the pathogenesis of rheumatoid arthritis, ischemia-reperfusion injury, chronic obstructive pulmonary disease, asthma and other inflammatory diseases, was established to elucidate the anti-inflammatory functions of 16-hydroxycleroda-3,13 (E)-dien-15-oic acid (PL3S) (Part I) and C18 fatty acids (Part II).
Part I: PL3S suppressed the generation of superoxide anion and the release of elastase in formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP)-activated human neutrophils in a concentration-dependent fashion with IC50 values of 3.06 0.20 and 3.30 0.48 μM, respectively. The anti-inflammatory effects were not due to cytotoxicity because culturing with PL3S did not cause lactate dehydrogenase release. PL3S did not display antioxidant and superoxide anion-scavenging ability. Additionally, neither subcellular NADPH oxidase activities nor cAMP-dependent pathways were altered by PL3S. PL3S significantly inhibited rapid calcium release from internal calcium stores caused by fMLP but not thapsigargin. Furthermore, PL3S suppressed phospholipase C activator-elicited elastase release in human neutrophils. In summary, these results suggest that the inhibitory effects of PL3S on respiratory burst and degranulation of human neutrophils may be through the inhibition of cytosolic calcium mobilization, but not via the cAMP-dependent pathways.
Part II: There is considerable evidence from clinical, experimental, and epidemiologic observations that fatty acids (FAs) and FA-derived compounds play a critical role in cellular viability and manipulation of FA homeostasis may open novel therapeutic avenues to against cardiovascular diseases and inflammatory diseases. In spite of this, the physiological role of C18 FAs in regulating neutrophil functions remains poorly understood. In this study, cis unsaturated (UST)FAs and linoelaidic acid, but not saturated (ST)FA nor other trans USTFAs, significantly inhibited the generation of O2•− and the release of elastase, as well as the accelerated resequestration of cytosolic calcium in fMLP-activated human neutrophils in a concentration-dependent fashion. As increase in number of double bound, the inhibitory actions of USTFAs were weakened. Additionally, cis USTFA with methyl ester did not share the inhibitions. These FAs did not display significant antioxidant and superoxide anion-scavenging ability. Furthermore, these inhibitory effects were not mediated by the cAMP-dependent pathways. cis USTFAs inhibited store-operated calcium entry in human neutrophils in response to fMLP, calcium ionophore A23187, and endomembrane calcium-ATPase inhibitor thapsigargin. In summary, the inhibition of human neutrophil functions by cis USTFAs and trans linoelaidic acid in fMLP-activated human neutrophils can probably be attributed to the blockade of calcium mobilization via the modulation of store-operated calcium entry.
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