Substance P Induces HO-1 Expression in RAW 264.7 Cells Promoting Switch towards M2-Like Macrophages

Abstract

Substance P (SP) is a neuropeptide that mediates many physiological as well as inflammatory responses. Recently, SP has been implicated in the resolution of inflammation through induction of M2 macrophages phenotype. The shift between M1-like and M2-like, allowing the resolution of inflammatory processes, also takes place by means of hemeoxygenase-1 (HO-1). HO-1 is induced in response to oxidative stress and inflammatory stimuli and modulates the immune response through macrophages polarisation. SP induces HO-1 expression in human periodontal ligament (PDL), the latter potentially plays a role in cytoprotection. We demonstrated that SP promotes M2-like phenotype from resting as well as from M1 macrophages. Indeed, SP triggers the production of interleukine-10 (IL-10), interleukine-4 (IL-4) and arginase-1 (Arg1) without nitric oxide (NO) generation. In addition, SP increases HO-1 expression in a dose- and time-dependent manner. Here we report that SP, without affecting cell viability, significantly reduces the production of pro-inflammatory cytokines and enzymes, such as tumor necrosis factor-alpha (TNF-α), interleukine-6 (IL-6), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), and ameliorates migration and phagocytic properties in LPS-stimulated RAW 264.7 cells. M2-like conversion required retention of NF-κB p65 into the cytoplasm and HO-1 induced expression. Silencing of the HO-1 mRNA expression reversed the induction of pro-inflammatory cytokines in RAW 264.7 stimulated by LPS and down-regulated anti-inflammatory hallmarks of M2 phenotype. In conclusion, our data show that SP treatment might be associated with anti-inflammatory effects in LPS-stimulated RAW 264.7 cells by suppressing NF-κB activation and inducing HO-1 expression.

Trimetallic Nitride Endohedral Fullerenes Carboxyl-Gd3N@C80: A New Theranostic Agent for Combating Oxidative Stress and Resolving Inflammation

“…24 Nrf2 is a basic leucine zipper (bZIP) protein that regulates the expression of antioxidative proteins, such as HO-1. 25 To examine the antioxidative and anti-inflammatory effect of carboxyl-Gd 3 N@C 80 , we pretreated Raw 264.7 cells with nanoparticle at 3.5 µ M for 20 h and LPS for another 4 h. Total RNA were isolated, reverse-transcribed to cDNA, and analyzed with real-time PCR. As shown in Figure 3, LPS significantly promoted the mRNA expression of iNOS (** p < 0.01) and TNF- α compared to the control (*** p < 0.001).…”

Composite PLA/PEG/nHA/Dexamethasone Scaffold Prepared by 3D Printing for Bone Regeneration

“…Early nonbacterial inflammation may result in damage to injured tissue and accelerate the eventual failure of many medical implants . Macrophages with a spectrum of possible phenotypes play an important role in inflammatory cascade . M1 (classical) and M2 (alternative) activation represent the two extremes of a continuum in a universe of activation states .…”

“…Accumulated release of NO in the medium is an indicator of the protein inducible nitric oxide synthase (iNOS), expressed by M1 macrophages. This enzyme could metabolize arginine to NO and citrulline . Figure 10 showed that after being treated with LPS, nitrite production (the stable metabolism of NO) from RAW 264.7 cells was promoted at both 6 and 24 h. When cells were exposed to Dex and LPS, a substantial suppression of NO production was detected.…”

“…This enzyme could metabolize arginine to NO and citrulline. [33] Figure 10 showed that after being treated with LPS, nitrite production (the stable metabolism of NO) from RAW 264.7 cells was promoted at both 6 and 24 h. When cells were exposed to Dex and LPS, a substantial suppression of NO production was detected. Dex released from scaffolds exhibited even better inhibitory activity than the control drug.…”

“…[32] Macrophages with a spectrum of possible phenotypes play an important role in inflammatory cascade. [33] M1 (classical) and M2 (alternative) activation represent the two extremes of a continuum in a universe of activation states. [34] Murine macrophage cell line RAW 264.7 was employed in this study for in vitro inflammatory assay.…”