Gene and Protein Expression Pattern of Cytokines in Disc Herniation Depend on Time of Symptoms

Abstract

Introduction Sciatica caused by lumbar disc herniation is a frequent clinical condition. The development of the radicular pain is explained by mechanical and biological (inflammatory) factors. Spontaneous pain relief in the first weeks is not uncommon, but a significant part of the patients have got persistent (and/or recurrent) disabling pain requiring surgical intervention. The biological background of the alteration in clinical symptoms is still unknown. Objective The aim of this study was to investigate the protein and the mRNA expression of different cytokines in human herniated disc tissues. Methods A total of 24 patients who underwent lumbar microdiscectomy were included into the study. Sequestered disc tissue was collected during the surgery and analyzed using a Human Cytokine Array Panel (R&D Systems) and TaqMan Gene Expression Assays to determine the protein ( n = 12) and mRNA expression ( n = 12) of different cytokines. Cytokine expression levels were analyzed in relation to the duration of the symptoms (acute: less than 6 weeks, chronic: more than 3 months). Nonparametric statistical tests were used to determine significant differences in protein/mRNA expression. A minimum of 1.5-fold difference and p < 0.05 was considered significant. Results IL-6, IL-8, and GRO-a were expressed significantly higher in acute disc herniations either in protein and mRNA levels. RANTES, IFN-g, and G-CSF proteins were found to be increased in chronic herniations and higher expression of RANTES and IFN-g were confirmed at mRNA level. Conclusions Cytokine profile in herniated disc tissue changes with time. It can be associated with an altered inflammation process and the consequent change of the clinical picture. New biological approach selectively modulating the inflammatory response can be one of the future developments in the nonsurgical management of intervertebral disc herniation.