A lack of Toll-like receptor 4 expression variability in the immediate preoperative period: a pilot study of elective surgical patients

Toll-like receptor 4 (TLR-4), a receptor of innate immunity, provides the site for the lipopolysaccharide shell of Gram-negative organisms to bind and initiate the inflammatory cascade in sepsis. Its expression has been studied in various disease states (sepsis, asthma, atherosclerosis, immunodeficiencies), ethnic groups (Chinese, Irish, Scottish, Gambian), ages, level of physical training, gestational status, and trauma. The expanding body of evidence in regard to TLR signaling is demonstrating the importance between such signaling and human disease. A translational research project between the Departments of Anesthesiology and Medical Microbiology and Immunology was initiated to determine any difference in the amount of TLR-4 expression in elective preoperative patients in regard to height, weight, age, sex, and body surface area (BSA), body mass index (BMI), hypertension, and diabetes. Race was not analyzed. After institutional research board approval, a prospective study of the blood specimens of 52 consecutive, elective, preoperative patients was performed. The blood was directly decanted into a PAXgene Blood RNA tube (Qiagen) designed for the stabilization of RNA from whole blood. Whole blood RNA was extracted using the PAXgeneTM Blood RNA System (PreAnalytiX, Hombrechitikon, Switzerland), including treatment with DNase I to prevent genomic DNA contamination. Quantification of TLR-4 expression levels in human lymphocytes was by RT-PCR and results compared with standard curves. Pearsons's correlation coefficient was use for statistical analysis of the continuous variables and t-testing was used in the analysis of the categorical variables. The TLR-4 concentration varied from 0.211 to 2.490 fmol/μ l per cDNA; however, there was no statistical significance between the concentration of TLR-4/cDNA expressed by RT-PCR and the continuous variables (height, weight, BMI, BSA, and age) nor the categorical variables (hypertension, diabetes, and sex) (Table 1). None of the patients had postoperative infections. This was an initial attempt to quantify the TLR-4 receptor expression by elective patient variable preoperatively. It provided an opportunity for anesthesiologists to take their practice to the laboratory to explore the immunologic basis of their actions.

Table 1 abstract P91