Effect of siRNA-induced inhibition of IL-6 expression in rat cerebral gliocytes on cerebral edema following traumatic brain injury

Abstract

The present study aimed to investigate the effect of RNA interference (RNAi) on the inhibition of interleukin (IL)‑6 expression in rat cerebral gliocytes in vitro and rat cerebral traumatic tissues in vivo, as well as the effect of RNAi on cerebral edema. pSUPER vectors containing IL‑6 small hairpin RNA (pSUPER‑IL‑6 1‑5) were designed, constructed and transfected into C6 rat glioma cells using cationic liposomes. ELISA was used to select the plasmid with the strongest interference effect. A freefall method was used to generate a rat brain injury model and rats were randomly divided into treatment, empty plasmid and control groups (n=14/group). IL‑6 levels, water content and sodium content were determined in the brain tissues at 24 and 72 h post‑injury. pSUPER‑IL‑6 was effectively transfected into C6 cells and was found to inhibit the expression of IL‑6 rather than IL‑8. The pSUPER‑IL‑6 1 vector was most effective in inducing RNAi. In vivo, IL‑6 levels were observed to be lowest in the interference group and there were statistically significant differences in water and sodium content among the experimental groups (P<0.05). RNAi was found to inhibit IL‑6 expression in vivo and in vitro in rat cerebral gliocytes, and the reduction of the IL‑6 levels was found to reduce post‑traumatic cerebral edema.

The Pathophysiology of Post-Traumatic Glioma

“…As it has been shown to date, the formation of glioma after injury may be associated with the inflammatory processes of the injury, whose main purpose is the elimination of damaged tissue components and the resumption of physiological activities [2]. In the entire body, this task is performed by the cells of the immune system that exist in the tissues and circulate in the blood; in the brain this role is specifically played by the microglia, in some cases aided by other cells of the immune system [2,10]. Injury-induced activation of microglia and the immune system is accompanied by several processes caused by external tissue damage, such as a hemorrhage, cerebral edema, and increased intracranial pressure—all related to the disruption of the brain’s protective and stabilizing structures and the blood–brain barrier [10].…”

“…In the entire body, this task is performed by the cells of the immune system that exist in the tissues and circulate in the blood; in the brain this role is specifically played by the microglia, in some cases aided by other cells of the immune system [2,10]. Injury-induced activation of microglia and the immune system is accompanied by several processes caused by external tissue damage, such as a hemorrhage, cerebral edema, and increased intracranial pressure—all related to the disruption of the brain’s protective and stabilizing structures and the blood–brain barrier [10]. Brain-repair processes in physiological conditions involve only microglia, usually isolated from other cells that perform repair functions, such as neutrophils and macrophages.…”

“…In addition, IL-6 in larger quantities adversely affects the microcirculation in the brain, increasing vascular permeability, and damaging the blood–brain barrier in a much wider area than the initial area. This function is very important in injuries that did not initially break the barrier because IL-6 allows the secondary entry of macrophages to the site of injury, and also exacerbates its course by creating brain edema [2,10]. IL-6 also plays a function in cell-cycle regulation processes, as has been proven in experimental studies in rats [10].…”

“…This function is very important in injuries that did not initially break the barrier because IL-6 allows the secondary entry of macrophages to the site of injury, and also exacerbates its course by creating brain edema [2,10]. IL-6 also plays a function in cell-cycle regulation processes, as has been proven in experimental studies in rats [10]. It activates signal transducer and activator of transcription 3 (STAT3), a protein responsible for cell growth, proliferation, differentiation, and apoptosis.…”

“…Another argument supporting the thesis of the pathophysiological role of IL-6 in the mechanism of glioma formation is its high concentrations and its receptors in cerebral spinal fluid in patients after head injury. Its high levels may cause the production of proinflammatory cytokines that induce an elevated inflammatory response in the body [10]. Although IL-6 is important for the proper functioning of the brain regardless of injury, and the inflammatory response itself is necessary for the proper healing process, excessive IL-6 concentrations can cause negative effects.…”