Toll-like receptor and cytokine gene expression in the early phase of human lung transplantation

Background: Innate immunity is the first line of host defense against invading microorganisms, which is mediated by specific pathogen recognition molecules called toll-like receptors (TLRs). TLRs can also recognize endogenous danger signals, resulting in cytokine production and activation of the adaptive immune system. We hypothesized that gene expression of TLRs during lung transplantation may be affected by the donor condition and the ischemia-reperfusion process, which may subsequently influence graft function. Methods: Lung biopsies from 14 patients were collected before and after reperfusion, and mRNA levels of TLRs, cytokines (interleukin [IL]-1 beta, IL-6, IL-8, IL-10 and interferon-gamma) and heat-shock protein 70 (HSP70) were measured by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR). Results: In cold-preserved donor lungs, all TLRs (except TLR3) showed significant correlations with one another and also with the cytokines examined. Expression of several TLRs and cytokines correlated with the intubation time of donors. TLR4 gene expression correlated closely with IL-8 before and after reperfusion (p <= 0.01). After reperfusion, HSP70 mRNAs increased significantly (P < 0.05). Conclusions: Differential expression levels of TLRS and cytokine genes likely reflect the inflammatory status of lung grafts; correlation of TLR genes with cytokine genes and clinical conditions implicates a potential role of TLRs in early graft responses.