Pro-inflammatory effects of commercial alpha-lactalbumin on RAW 264.7 macrophages is due to endotoxin contamination |
| |
Authors: | I-Chun Lin Cheng-Deng Kuo |
| |
Affiliation: | Laboratory of Biophysics, Department of Research and Education, Taipei Veterans General Hospital, Taipei 112, Taiwan |
| |
Abstract: | This study investigated the effects of alpha-lactalbumin (α-LA) on cellular signaling molecules associated with inflammatory responses in RAW 264.7 macrophages. The results indicated that commercial α-LA could increase prostaglandin E2 (PGE2) and the expression of COX-2 via increased phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), p38 mitogen-activated protein kinase (MAPK) and jun N-terminal kinase (JNK), and increase nitric oxide (NO) and the expression of iNOS via the activation of ERK1/2 and JNK. Furthermore, commercial α-LA could increase nuclear translocation of p65 nuclear factor-kappa B (p65 NF-κB) through stimulation on inhibitor kappa B-alpha (IκB-α) degradation. Since endotoxin also has these effects, we assayed the content of endotoxin in the commercial α-LA. We found to our surprise that endotoxin was there and that α-LA-induced NO and PGE2 production could be suppressed by polymyxin B, a specific inhibitor of endotoxin. Thus, the pro-inflammatory effects of commercial α-LA might be caused by endotoxin contamination through activation and expression of iNOS and COX-2 which were upregulated by MAPKs or nuclear translocation of p65 NF-κB in RAW 264.7 cells. It is therefore crucial to assess the possibility of endotoxin contamination within any biological product being studied for immune augmenting activities before a meaning result can be obtained. |
| |
Keywords: | α-LA, alpha-lactalbumin COX-2, cyclooxygenase-2 Cur, curcumin DAPI, 4&prime ,6-diamidino-2-phenylindole Dex, dexamethasone ERK1/2, extracellular signal-regulated kinase 1/2 IκB-α, inhibitor kappa B-alpha iNOS, inducible nitric oxide synthase JNK, jun N-terminal kinase l-NAME, Nω-nitro-l-arginine methyl ester LPS, lipopolysaccharide MAPK, mitogen-activated protein kinase MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide NO, nitric oxide NF-κB, nuclear factor-kappa B PGE2, prostaglandin E2 NS-398, N-[2-(cyclohexyloxy)-4-nitrophenyl]methanesulfonamide PMB, polymyxin B |
本文献已被 ScienceDirect 等数据库收录! |
|