Piezo1 channel‐mediated Ca²⁺ signaling inhibits lipopolysaccharide‐induced activation of the NF‐κB inflammatory signaling pathway and generation of TNF‐α and IL‐6 in microglial cells

Abstract

Microglial cells are crucial in maintaining central nervous system (CNS) homeostasis and mediating CNS disease pathogenesis. Increasing evidence supports that alterations in the mechanical properties of CNS microenvironments influence glial cell phenotypes, but the mechanisms regulating microglial cell function remain elusive.Here, we examined the mechanosensitive Piezo1 channel in microglial cells, particularly, how Piezo1 channel activation regulates pro-inflammatory activation and production of pro-inflammatory cytokines, using BV2 and primary microglial cells.Piezo1 expression in microglial cells was detected both at mRNA and protein levels.Application of Piezo1 channel activator Yoda1 induced Ca 2+ flux to increase intracellular Ca 2+ concentration that was reduced by treatment with ruthenium red, a Piezo1 inhibitor, or Piezo1-specific siRNA, supporting that Piezo1 functions as a cell surface Ca 2+ -permeable channel. Priming with lipopolysaccharide (LPS) induced microglial cell activation and production of TNF-α and IL-6, which were inhibited by treatment with Yoda1. Furthermore, LPS priming induced the activation of ERK, p38 MAPKs, and NF-κB. LPS-induced activation of NF-κB, but not ERK and p38, was inhibited by treatment with Yoda1. Yoda1-induced inhibition was blunted by siRNA-mediated depletion of Piezo1 expression and, furthermore, treatment with BAPTA-AM to prevent intracellular Ca 2+ increase. Collectively, our results support that Piezo1 channel activation downregulates the pro-inflammatory function of microglial cells, especially production of TNF-α and IL-6, by initiating intracellular Ca 2+ signaling to inhibit the NF-κB inflammatory signaling pathway. These findings reveal Piezo1 channel activation as a previously unrecognized mechanism regulating microglial cell function, raising an interesting perspective on targeting this molecular mechanism to alleviate neuroinflammation and associated CNS pathologies.

Mechanical properties of the brain: Focus on the essential role of Piezo1‐mediated mechanotransduction in the CNS

“…Activation of Piezo1 exerts an anti-inflammatory effect through inhibition of the NF-κB pathway, but not the extracellular signal-regulated kinase (ERK) and p38 pathways (Malko et al, 2023). Consistent with this, showed that inhibition of Piezo1 promotes LPSmediated secretion of pro-inflammatory cytokines from microglia.…”

“…In the brain, in the presence of inflammation-stimulating factors (Aβ or LPS), activation of Piezo1 tends to suppress the pro-inflammatory phenotype of glial cells. Malko et al (2023) showed that 0.3-3 μM Yoda1 inhibited LPS-induced microglial activation and production of the pro-inflammatory factors TNF-α and IL-6, which could be abolished by GsMTx4 or siPiezo1RNA.…”

T cell polarization and NFAT translocation are stiffness-dependent and are differentially regulated by Piezo1 and Orai1

“…Considering our findings, shear stress-potentiated NFAT translocation should be independent of Piezo1 but regulated by CRAC/Orai1 channels. Interestingly, in microglial cells, considered the major immune cell type in the brain, activation of NFAT proteins is also independent of Piezo1 57 . In many other cell types, however, we noticed that Piezo1-mediated mechanosensing is linked to activation of the NFAT family, including macrophages 58 , osteoblasts 59 , erythroblasts 60 , colon cancer stem-like cells 61 , and cardiomyocytes 62 .…”

Neuroprotective mechanism of salvianolic acid B against cerebral ischemia–reperfusion injury in mice through downregulation of TLR4, p‐p38MAPK, p‐JNK, NF‐κB, and IL‐1β

“…As nuclear targets of MAPKs pathways, NF‐κB occupies a key position in the inflammatory response process. When cells are activated by signals, they respond by activating NF‐κB by promoting the phosphorylation and degradation of I‐κB 31 . Then, the activated NF‐κB is translocated into the nucleus, resulting in the transcriptional expression of genes correlated with cellular growth properties 32 .…”