Effects of total ginsenosides from Panax ginseng stems and leaves on gut microbiota and short-chain fatty acids metabolism in acute lung injury mice / 中国中药杂志

This study aimed to investigate the biological effects and underlying mechanisms of the total ginsenosides from Panax ginseng stems and leaves on lipopolysaccharide(LPS)-induced acute lung injury(ALI) in mice. Sixty male C57BL/6J mice were randomly divided into a control group, a model group, the total ginsenosides from P. ginseng stems and leaves normal administration group(61.65 mg·kg~(-1)), and low-, medium-, and high-dose total ginsenosides from P. ginseng stems and leaves groups(15.412 5, 30.825, and 61.65 mg·kg~(-1)). Mice were administered for seven continuous days before modeling. Twenty-four hours after modeling, mice were sacrificed to obtain lung tissues and calculate lung wet/dry ratio. The number of inflammatory cells in bronchoalveolar lavage fluid(BALF) was detected. The levels of interleukin-1β(IL-1β), interleukin-6(IL-6), and tumor necrosis factor-α(TNF-α) in BALF were detected. The mRNA expression levels of IL-1β, IL-6, and TNF-α, and the levels of myeloperoxidase(MPO), glutathione peroxidase(GSH-Px), superoxide dismutase(SOD), and malondialdehyde(MDA) in lung tissues were determined. Hematoxylin-eosin(HE) staining was used to observe the pathological changes in lung tissues. The gut microbiota was detected by 16S rRNA sequencing, and gas chromatography-mass spectrometry(GC-MS) was applied to detect the content of short-chain fatty acids(SCFAs) in se-rum. The results showed that the total ginsenosides from P. ginseng stems and leaves could reduce lung index, lung wet/dry ratio, and lung damage in LPS-induced ALI mice, decrease the number of inflammatory cells and levels of inflammatory factors in BALF, inhibit the mRNA expression levels of inflammatory factors and levels of MPO and MDA in lung tissues, and potentiate the activity of GSH-Px and SOD in lung tissues. Furthermore, they could also reverse the gut microbiota disorder, restore the diversity of gut microbiota, increase the relative abundance of Lachnospiraceae and Muribaculaceae, decrease the relative abundance of Prevotellaceae, and enhance the content of SCFAs(acetic acid, propionic acid, and butyric acid) in serum. This study suggested that the total ginsenosides from P. ginseng stems and leaves could improve lung edema, inflammatory response, and oxidative stress in ALI mice by regulating gut microbiota and SCFAs metabolism.

Functionally diverse ligands modulate different activation states of the formyl peptide receptor 2, a G protein-coupled receptor / 中国药理学与毒理学杂志

OBJECTIVE To identify the mechanisms by which the formyl peptide receptor 2 (FPR2) mediates both inflammatory and anti-inflammatory signaling in an agonist-dependent manner. METHODS Cells expressing FPR2 were incubated with weak agonists, Aβ42 and Ac2-26, before stimulation with a strong agonist, WKYMVm. Calcium mobilization, cAMP inhibition and MAP kinase activation were measured. Intramolecular FRET were determined using FPR2 constructs with an ECFP attached to the C- terminus and a FlAsH binding motif embedded in the first or third intracellular loop (IL1 or IL3, respectively). RESULTS Aβ42 did not induce significant Ca2 + mobilization, but positively modulated WKYMVm-induced Ca2 + mobilization and cAMP reduction in a dose-variable manner within a narrow range of ligand concentrations. Treating FPR2-expressing cells with Ac2-26, a peptide with anti-inflam?matory activity, negatively modulated WKYMVm-induced Ca2 + mobilization and cAMP reduction. Intra?molecular FRET assay showed that stimulation of the receptor constructs with Aβ42 brought the C-terminal domain closer to IL1 but away from IL3. An opposite conformational change was induced by Ac2-26. The FPR2 conformation induced by Aβ42 corresponded to enhanced ERK phosphorylation and attenuated p38 MAPK phosphorylation, whereas Ac2-26 induced FPR2 conformational change corresponding to elevated p38 MAPK phosphorylation and reduced ERK phosphorylation. CONCLUSION Aβ42 and Ac2-26 induce different conformational changes in FPR2. These findings provide a structural basis for FPR2 mediation of inflammatory vs anti-inflammatory functions and identify a type of receptor modulation that differs from the classic positive and negative allosteric modulation.

Biphasic modulation of chemerin peptide-induced calcium flux and ERK phosphorylation by amyloid beta peptide / 中国药理学与毒理学杂志

OBJECTIVE The chemokine-like receptor 1 (CMKLR1, ChemR23) is a functional receptor for chemerin, the chemerin-derived nonapeptide (C9), and the amyloid β peptide 1-42 (Aβ42). Because these peptides share little sequence homology, studies were conducted to investigate their pharmaco?logical properties and regulation at CMKLR1. METHODS Cells expressing CMKLR1 were incubated with Aβ42 before stimulation with a strong agonist, the C9 peptide. Calcium mobilization, cAMP inhibition and MAP kinase activation were measured. Intramolecular FRET were determined using CMKLR1 constructs with an ECFP attached to the C- terminus and a FlAsH binding motif embedded in the first intracellular loop (IL1). RESULTS Binding of both Aβ42 and the C9 peptide induced CMKLR1 internal?ization, but only the Aβ42-induced receptor internalization involved clathrin-coated pits. Likewise, Aβ42 but not C9 stimulated β-arrestin 2 translocation to plasma membranes. A robust Ca2+ flux was observed following C9 stimulation, whereas Aβ42 was ineffective even at micromolar concentrations. Despite its low potency in calcium mobilization assay, Aβ42 was able to alter C9 -induced Ca2+ flux in dose-dependent manner: a potentiation effect at 100 pmol·L-1 of Aβ42 was followed by a suppression at 10 nmol·L-1 and further potentiation at 1 μmol·L-1. This unusual and biphasic modulatory effect was also seen in the C9-induced ERK phosphorylation but the dose curve was opposite to that of Ca2+ flux and cAMP inhibition, suggesting a reciprocal regulatory mechanism. Intramolecular FRET assay confirmed that Aβ42 modulates CMKLR1 rather than its downstream signaling pathways. CONCLUSION These findings suggest Aβ42 as an allosteric modulator that can both positively and negatively regulate the activation state of CMKLR1 in a manner that differs from existing allosteric modulatory mechanisms.