ANALYSING OF THE EFFECTS OF AN INTERLEUKIN – 1 RECEPTOR ANTAGONIST AND A RNA POLYMERASE INHIBITOR ON NEURODEGENERATION IN THE HIPPOCAMPAL CELL LINE
Authors: Şahin Mehtap , Filiz Ahmet Kemal 
Published: June 2024

Objective: Glutamate is the principal excitatory neurotransmitter in the central nervous system involved in various neurophysiological functions. Both in infectious and non-infectious conditions, excessive extracellular cerebral glutamate-induced excitotoxicity is known to be triggered. Disruption of its homeostasis can be detrimental to neurons and ultimately leads to cell death. This pathological process, known as excitotoxicity, can induce neuronal cell degeneration following the overstimulation of glutamate on specific ionotropic receptors. Activation of these receptors results in neural calcium influx, which can mediate excitotoxicity through a cascade of events, including free radical production, mitochondrial dysfunction, and activation of various enzymes involved in normal cell development and function, leading to damage to the cell membrane, cytoskeleton, and DNA. Due to their heightened sensitivity to glutamate, the hippocampal HT22 cell line is utilized for modeling neurodegenerative diseases. Anakinra, an interleukin-1 receptor antagonist, is used for preventing inflammation in many autoinflammatory diseases. The aim of the present study is to investigate the anti-inflammatory and/or anti-neurodegenerative effects of favipiravir, a RNA polymerase inhibitor, and anakinra, an interleukin-1 receptor antagonist, on glutamate-induced cytotoxicity. To this end, the HT22 cell line was employed, and cell cultures were maintained under appropriate conditions.
Methods: Five groups of cells were established to examine the effects of anakinra and favipiravir on glutamate-induced cytotoxicity. The control group received no treatment. The group induced with glutamate received 10 mM of glutamate for 24 hours. The anakinra group was exposed to different concentrations (1, 10, 25, 50, and 100 µg) of anakinra for 24 hours. The favipiravir group was exposed to different concentrations (1, 10, 25, 50, and 100 µg) of favipiravir for 24 hours. The anakinra+glutamate group was pre-treated with anakinra at various concentrations (1, 10, 25, 50, and 100 µg) for 1 hour and then exposed to 10 mM of glutamate for 24 hours. The favipiravir+glutamate group was pre-treated with favipiravir at various concentrations (1, 10, 25, 50, and 100 µg) for 1 hour and then exposed to 10 mM of glutamate for 24 hours. Effective doses were subsequently determined, and combinations of anakinra+favipiravir+glutamate were applied. Cell viability was assessed using the XTT test.
Results: The results indicated that favipiravir did not have any effects on cell viability after glutamate application in the HT22 cell line. Viability was not affected by the application of different doses of favipiravir alone (p < 0.01 compared to the control group). When examining the effect of anakinra on cell viability after glutamate application in the HT22 cell line, it was observed that the group treated with 100 µg anakinra showed higher viability compared to other groups (p < 0.01 compared to glutamate). Viability was not affected by the application of different doses of anakinra alone (p< 0.01 compared to the control group). However, anakinra was observed to prevent the cytotoxicity induced by glutamate in the HT22 cell line when applied at 100 µg, exhibiting a protective effect against neurodegeneration at this dose. In the group where anakinra and favipiravir were combined and applied with glutamate, anakinra showed a protective effect against glutamate toxicity, but the combination of anakinra and favipiravir did not alter this effect.
Conclusion: More extensive animal and human studies are required to determine the clinical implications of these findings.