AGEs mediated expression and secretion of TNF alpha in rat retinal microglia.
Diabetic retinopathy induces an inflammatory response in the retina characterized by an increase in inflammatory cytokines and the activation of microglia. The degree of microglia activation may influence the extent of retina injury following retinal metabolic stress. We have previously shown that DR rats have elevated levels of advanced glycation end products (AGEs) in their blood. We have also suggested that AGEs might be involved in microglial activation and production of tumor necrosis factor alpha (TNF alpha). In this study, we attempted to confirm that AGEs induce the release of TNF alpha from rat retinal microglia using an in vitro microglia culture system, and concurrently to explore the mediating mechanisms. AGEs increased the protein secretion and mRNA expression of TNF alpha in cultured rat retinal microglia. These effects of AGEs were primarily mediated by reactive oxygen species (ROS). Furthermore, the inhibitors for mitogen-activated protein kinases (MAPK; p38, JNK and ERK 1/2) and nuclear factor-kB (NF-kB) could significantly decrease AGEs-induced TNF alpha release. AGEs-activated microglia showed an increase of NF-kB p65 nuclear translocation. These observations indicated that pathophysiological levels of AGEs may alter rat retinal microglia function by up-regulating TNF alpha expression and release via enhanced formation of intracellular ROS. AGEs-induced ROS subsequently activates MAPK (p38, JNK and ERK1/2) and NF-kB.
Wang
Ai Ling
AL
Peking University Eye Centre, Peking University Third Hospital, Peking University, Beijing 100083, China. alwang@bjmu.edu.cn
Yu
Albert C H
AC
He
Qi Hua
QH
Zhu
Xiu'An
X
Tso
Mark O M
MO
D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000494:pharmacology; D039481:CD11b Antigen / Q000378:metabolism; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects; D017127:Glycation End Products, Advanced / Q000494:pharmacology / Q000502:physiology*; D017493:Leukocyte Common Antigens / Q000378:metabolism; D017628:Microglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics; D009363:Neoplasm Proteins / Q000235:genetics; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000502:physiology; D014178:Translocation, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
D000975:Antioxidants; D039481:CD11b Antigen; D017127:Glycation End Products, Advanced; D016328:NF-kappa B; D009363:Neoplasm Proteins; D029543:Nucleocytoplasmic Transport Proteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; C063447:p65 oncofetal mRNA transport protein, rat; D017493:Leukocyte Common Antigens