Inflammation and oxidative stress are both central contributors to a variety of neurodegenerative diseases (Bagyinszky et al., 2017; Leszek et al., 2016). Microglia are the resident macrophage-like immune cells in the brain and spinal cord, providing the first line of immunological defence. However, in disease, these cells become chronically activated, contributing to extensive neuronal damage (Rice et al., 2015). Dampening this activation may provide neurons critical protection against chronic inflammatory and oxidative damage.
The aim of this study was to determine lipopolysaccharide (LPS)-induced inflammation and reactive oxygen species (ROS) release could be inhibited through the activation of the receptor Fpr2, known to play an important role in peripheral inflammatory resolution (de Oliveira et al., 2017).
Immortalised murine microglia (BV2 cells) were stimulated with LPS (50ng/ml) for 1h prior to treatment with one of two Fpr2 ligands, Cpd43 or Quin-C1 (both 100nM). Cytokine (TNFα and IL-10) and nitric oxide (NO) production was detected at 24 and 48h. Following previous data investigating Fpr2 signaling (Cooray et al., 2013), FR180204 (10μM) or SB203580 (2μM), ERK1/2 and p38 MAP kinase blockers respectively, was added 10 minutes prior to either Fpr2 agonist. NO detection a 24h was then repeated. ROS were detected over time with carboxy-H2DCFDA. LPS was administered for 30 minutes prior to Cpd43 or Quin-C1, with ROS production recorded every 5 minutes for up to 1h. The protein expression of Annexin A1 – an endogenous ligand of Fpr2 with anti-inflammatory effects (Ries et al., 2016) – following Cpd43 or Quin-C1 treatment for 24h was determined by Western blot.
Treatment with both Cpd43 and Quin-C1 significantly suppressed LPS-induced production of TNFα and NO at 24 and 48h. The suppression of NO was then blocked through the addition of SB203580. FR180204 had no effect. The anti-inflammatory effects may due to increased expression of AnxA1, which was detected at 24h. Further, both agonists enhanced production of IL-10 48h-post LPS exposure. Strikingly, both Cpd43 and Quin-C1 completely abolished LPS-induced ROS, with levels similar to untreated.
Combined, these data highlight Fpr2 as novel therapeutic target to tackle inflammation and oxidative stress in neurodegenerative disease, through a synergistic pharmacological function.
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Cooray et al. (2013). Proc Natl Acad Sci U S A 110: 18232-7.
de Oliveira et al. (2017). Eur J Pharmacol 805: 46-50.
Leszek et al. (2016). CNS Neurol Disord Drug Targets 15: 329-36.
Rice et al. (2015). J Neurosci 35: 9977-9989.
Ries et al. (2016). J Neuroinflammation 13: 1-15.