The influence of blueberry (Vaccinium myrtillus) leaf extract on peroxisomal function in microglial cells

The presented study investigated possible antioxidant and anti-inflammatory properties of Vaccinium myrtillus (VM) extract in murine BV-2 microglial cells, including both wild-type (Wt) and Acyl-CoA oxidase 1-deficient (Acox1^-/-) cell lines.

The radical scavenging activity was assessed by DPPH assay. The MTT test was used assess the cell viability. Nitric oxide production by cells was quantified by Griess reagent. Catalase activity was evaluated by photometric measurement of the H₂O₂ decomposition. The measurement of ACOX1 activity was performed using a fluorometry-based assay. Immunoblotting and RT-qPCR techniques were employed to measure protein expression and gene transcription in treated cells. Statistical analysis was conducted using GraphPad Prism, with significance determined at p < 0.05.

Radical scavenging activity test assessed the yielded an IC50 value 0.03613 mg/mL, prompting further functional investigations. Lipopolysaccharide (LPS) stimulation reduced ACOX1 enzymatic activity by approximately 40% in Wt cells. Co-treatment with VM extract restored the activity to initial levels. LPS exposure increased catalase activity and mRNA expression by 1.5-fold each in Wt cells and 2-fold and 4-fold, respectively, in mutant Acox1^-/- cells. VM treatment normalized these parameters in Wt cells and significantly attenuated them by about 20% in mutant cells. In addition, the extract also modulated Abcd1 mRNA expression, a gene involved in fatty acid transport into peroxisomes, suggesting a significant influence on cellular peroxisomal lipid handling and redox balance. LPS markedly induced some inflammatory markers, with iNos mRNA and Nitric oxide (NO) levels, increasing up to ~10-fold and ~20-fold, respectively, in Acox1^-/- cells. Similarly, Il-1β and Tnf-α mRNA levels were induced by approximately 4 to 30-fold in Wt cells and more than 180- fold in mutant cells. VM extract significantly reduced LPS-induced NO production and downregulated iNos, Tnf-α, and Il-1β mRNA expression in both cell lines.

Overall, our findings demonstrate that V. myrtillus extract suppresses the oxidative-stress induced elevated levels of inflammatory markers and probably modulate peroxisomal metabolism. Although the precise molecular mechanisms remain to be clarified, the data support further investigation into the role of peroxisomal lipid metabolism in mediating the biological effects of this extract.