Punicalagin Attenuates LPS-Induced Inflammation and ROS Production in Microglia by Inhibiting the MAPK/NF-κB Signaling Pathway and NLRP3 Inflammasome Activation

Abstract

Purpose Neurodegenerative diseases are associated with neuroinflammation along with activation of microglia and oxidative stress, but currently lack effective treatments. Punicalagin is a natural bio-sourced product that exhibits anti-inflammatory effects on several chronic diseases; however, the anti-inflammatory and anti-oxidative effects on microglia have not been well examined. This study aimed to investigate the effects of punicalagin on LPS-induced inflammatory responses, NLRP3 inflammasome activation, and the production of ROS using murine microglia BV2 cells. Methods BV2 cells were pre-treated with punicalagin following LPS treatment to induce inflammation. The secretion of NO and PGE 2 was analyzed by Griess reagent and ELISA respectively, while the expressions of iNOS, COX-2, STAT3, ERK, JNK, and p38 were analyzed using Western blotting, the production of IL-6 was measured by ELISA, and the activity of NF-κB was detected using promoter reporter assay. To examine whether punicalagin affects NLRP3 inflammasome activation, BV2 cells were stimulated with LPS and then treated with ATP or nigericin. The secretion of IL-1β was measured by ELISA. The expressions of NLRP3 inflammasome-related proteins and phospho IκBα/IκBα were analyzed using Western blotting. The production of intracellular and mitochondrial ROS was analyzed by flow cytometry. Results Our results showed that punicalagin attenuated inflammation with reduction of pro-inflammatory mediators and cytokines including iNOS, COX-2, IL-1β, and reduction of IL-6 led to inhibition of STAT3 phosphorylation by LPS-induced BV2 cells. Punicalagin also suppressed the ERK, JNK, and p38 phosphorylation, attenuated NF-κB activity, inhibited the activation of the NLRP3 inflammasome, and reduced the production of intracellular and mitochondrial ROS by LPS-induced BV2 cells. Conclusion Our results demonstrated that punicalagin attenuated LPS-induced inflammation through suppressing the expression of iNOS and COX-2, inhibited the activation of MAPK/NF-κB signaling pathway and NLRP3 inflammasome, and reduced the production of ROS in microglia, suggesting that punicalagin might have the potential in treating neurodegenerative diseases.

Antioxidant Activities of Natural Compounds from Caribbean Plants to Enhance Diabetic Wound Healing

“…Jung Lo et al were able to demonstrate that pretreatment with punicalagin of LPS-treated murine BV2 microglia cells attenuated inflammation with a reduction in the secretion of the pro-inflammatory cytokines iNOS, IL-1β, and IL-6. There was also a decrease in NF-κB activity and inhibition of NLRP3 activation [209]. The antioxidant properties of punicalagin are known.…”

“…Indeed, it is known to scavenge 2,2-diphenyl-1picrylhydrazyl radical (DPPH) and hydrogen peroxide H 2 O 2 [210,211]. It is also known to decrease the production of intracellular and mitochondrial ROS [209]. Furthermore, punicalagin enhances Nrf2 and HO-1 expression in RAW264.7 macrophages, where oxidative stress was induced by LPS.…”

Modulation of secretory factors by lipofundin contributes to its anti‑neuroinflammatory effects

“…1F , treatment with lipofundin in the concentration range of 62.5-250 µg/ml significantly reduced NO production compared with that in cells treated with LPS alone, with the maximal anti-inflammatory effect observed at a concentration of 125 µg/ml. During the activation of BV2 cells, NOS2 expression is highly upregulated, leading to the generation of a large amount of NO ( 13 ). To evaluate the activation status of BV2 cells, the expression of NOS2 was assessed using western blot analysis.…”

Oral administration of punicalagin attenuates imiquimod‐induced psoriasis by reducing ROS generation and inflammation via MAPK/ERK and NF‐κB signaling pathways

“…Moreover, Xu et al found that the phosphorylation of STAT3 contributed to PU‐induced HO‐1 expression during M2c phenotype polarization (Xu et al, 2017). Lo et al demonstrated that PU reduces the secretion of IL‐6 and inhibits the phosphorylation of STAT3 in LPS‐induced BV2 cells (Lo et al, 2022). Our results showed that PU inhibits the phosphorylation of p65 and ERK1/2 in a time‐ and dose‐dependent manner in HEKa and HaCaT cells.…”