Gene Expression Profile of Toll-Like Receptor/Adaptor/Interferon Regulatory Factor/Cytokine Axis During Liver Regeneration After Partial Ischemia-Reperfusion Injury

Abstract

Toll-like receptors and downstream signal transduction pathways play pivotal roles in induction of inflammation, which is crucial for liver injury and regeneration. Using a mouse model of partial hepatic ischemia-reperfusion injury followed by a 28-day time course for liver repair and regeneration, we assessed gene expression levels for Toll-like receptors, myeloid differentiation primary response 88, TIR-domain-containing adapter-inducing interferon-β, nuclear factor κB, interferon regulatory factors, tumor necrosis factor-α, and interleukins 1β and 6 at days 1, 4, 7, 14, and 28 after reperfusion in liver and blood cells by quantitative polymerase chain reaction. Mouse liver was gradually injured until 24 hours after reperfusion, and necrotic areas remained for 7 days. Concurrent with liver necrosis, overexpression of hepatocyte growth factor in blood cells (days 1-14), transient overexpression of cyclin D1 at day 7 in hepatic cells, and overexpression of transforming growth factor-β1 at days 7 and 14 in blood cells were used to characterize the priming, proliferative, and termination phases of liver regeneration. Liver regeneration was associated with significant up-regulation of Toll-like receptor 4, p65, interferon regulatory factors 1, 3, 9, tumor necrosis factor-α, and interleukin 1β at 24 hours. Liver regeneration was also associated with persistent overexpression of MyD88 (days 1-28) and with delayed TIR-domain-containing adapter-inducing interferon-β (days 4-28) in hepatic cells. In peripheral blood cells, Toll-like receptor 2 and MyD88 were up-regulated at 24 hours and Toll-like receptor 4 (days 1-14) and interferon regulatory factor 1 (days 1-7) showed persistent overexpression concomitant with interferon regulatory factor 5 (days 7-14); interleukin 1β (days 1-28) and interleukin 6 (day 4-28) also showed persistent expression. We depict for the first time a prospective view of cooperative transcriptional activation of Toll-like receptors/adaptors/interferon regulatory factors/cytokines in both liver and blood cells during different phases of liver repair after ischemia-reperfusion injury.