Abstract
Purpose :
Aging and inflammation are major factors in age-related ocular diseases. Expression of the P2X7 receptor (P2X7R) has been demonstrated in the eye. Activation of P2X7R could cause ocular cell dysfunction and death. The purpose of this study was to determine whether aging and lipopolysaccharide (LPS) could regulate the expression of P2X7R and its splice variants in mouse eyes.
Methods :
Male young (4 months old) and old (18 months old) C57BL/6 mice were intraperitoneally injected with either Escherichia coli O111:B4 LPS (LPS groups) or saline (control groups) and sacrificed 0, 3, 24, 48 or 72 hours later. Total RNAs were extracted from eye tissue with TRIzol reagent, and reverse transcripted. Quantitative polymerase chain reaction analysis was used to detect the specific mRNAs for P2X7R (P2X7R-V1) and its splice variants (P2X7R-V2, P2X7R-V3 and P2X7R-V4), and for pro-inflammatory cytokines (IL-6, TNF-α, IL-18 and IL-1β).
Results :
Baseline mRNA levels for ocular P2X7R-V1, P2X7R-V2, P2X7R-V3 and P2X7R-V4 in old mice appeared to be higher than those in young mice. LPS stimulation led to up-regulation of mRNA levels for P2X7R-V1, P2X7R-V2, P2X7R-V3, IL-6, and IL-1β in young mice, but down-regulation of mRNA levels for P2X7R-V1, P2X7R-V3, P2X7R-V4, TNF-α, IL-18, and IL-1β in old mice (P < 0.05). In both control and LPS groups, old mice had greater mRNA levels for P2X7R-V1, V2, V3, and V4 than young mice (P < 0.05). In control groups, mRNA levels for IL-6, TNF-α, IL-18 and IL-1β in old mice were higher than those in young mice (P < 0.05). In LPS groups, mRNA levels for IL-6, TNF-α, IL-18 and IL-1β in old mice were initially lower than those in young mice, but were higher than those in young mice at later time points.
Conclusions :
Our results show that aging upregulates mRNA expression of ocular P2X7R and its splice variants in mice. LPS differentially regulates the expression of P2X7R and its splice variants in young and old mice. Aging and LPS could impact P2X7R function via regulating the expression of P2X7R and its splice variants.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.