A Ganoderma-Derived Compound Exerts Inhibitory Effect Through Formyl Peptide Receptor 2

Renoprotective effect of isoliquiritigenin on cisplatin-induced acute kidney injury through inhibition of FPR2 in macrophage

Acute kidney injury (AKI) is a serious complication in critically ill patients. Accumulating evidences indicated that macrophages play an important pro-inflammatory role in AKI and isoliquiritigenin (ISL) can inhibit macrophagic inflammation, but its role in AKI and the underlying mechanism are unknown. The present study aims to investigate the renoprotective effect of ISL on AKI and the role of Formyl peptide receptors 2 (FPR2) in this process. In this study, cisplatin-induced AKI model and lipopolysaccharide-induced macrophage inflammatory model were employed to perform the in vivo and in vitro experiments. The results showed that ISL strongly relieved kidney injury and inhibited renal inflammation in vivo and suppress macrophagic inflammatory response in vitro. Importantly, it was found that FPR2 was significantly upregulated compared to the control group in AKI and LPS-induced macrophage, whereas it was strongly suppressed by ISL. Interestingly, overexpression of FPR2 with transfection of pcDNA3.1-FPR2 effectively reversed the anti-inflammatory effect of ISL in macrophage, suggesting that FPR2 may be the potential target for ISL to prevent inflammation and improve kidney injury of AKI. Take together, these findings indicated that ISL improved cisplantin-induced kidney injury by inhibiting FPR2 involved macrophagic inflammation, which may provide a potential therapeutic option for AKI.

Caulerpin Mitigates Helicobacter pylori-Induced Inflammation via Formyl Peptide Receptors

The identification of novel strategies to control Helicobacter pylori (Hp)-associated chronic inflammation is, at present, a considerable challenge. Here, we attempt to combat this issue by modulating the innate immune response, targeting formyl peptide receptors (FPRs), G-protein coupled receptors that play key roles in both the regulation and the resolution of the innate inflammatory response. Specifically, we investigated, in vitro, whether Caulerpin—a bis-indole alkaloid isolated from algae of the genus Caulerpa—could act as a molecular antagonist scaffold of FPRs. We showed that Caulerpin significantly reduces the immune response against Hp culture filtrate, by reverting the FPR2-related signaling cascade and thus counteracting the inflammatory reaction triggered by Hp peptide Hp(2–20). Our study suggests Caulerpin to be a promising therapeutic or adjuvant agent for the attenuation of inflammation triggered by Hp infection, as well as its related adverse clinical outcomes.

FPR2-based anti-inflammatory and anti-lipogenesis activities of novel meroterpenoid dimers from Ganoderma

Four pairs of novel meroterpenoid dimers, (±)-applandimeric acids A-D (1-4) with an unprecedented spiro[furo[3,2-b]benzofuran-3,2'-indene] core were isolated from the fruiting bodies of Ganoderma applanatum. Their planar structures were unambiguously determined via extensive spectroscopic analysis. Their relative and absolute configurations were confirmed through calculated internuclear distance, coupling constant, ¹³C NMR with DP4 + analysis and electronic circular dichroism (ECD). Furthermore, the molecular docking-based method was used to evaluate their interaction with formyl peptide receptor 2 (FPR2) associated with inflammation. Interestingly, (±)-applandimeric acid D (4) can bond with FPR2 by some key hydrogen bonds. Furthermore, an in vitro bioassay verified that 4 can inhibit the expression of FPR2 with IC₅₀ value of 7.93 μM. In addition, compared to the positive control LiCl (20 mM), 4 showed comparable anti-lipogenesis activity at the concentration of 20 μM. Meanwhile, 4 can suppress the protein levels of peroxisome proliferators-activated receptor-γ (PPAR-γ), CCAAT/enhancer-binding protein-β (C/EBP-β), adipocyte fatty acid-binding protein 4 (FABP4), and fatty acid synthase (FAS) through activating AMP-activated protein kinase (AMPK) signaling pathway. Thus, our findings indicate that compound 4 could be a lead compound to treat obesity and obesity-related diseases by inhibiting lipid accumulation in adipocyte and alleviating inflammation.

Label-free cell phenotypic study of opioid receptors and discovery of novel mu opioid ligands from natural products

ETHNOPHARMACOLOGICAL RELEVANCE

Mu opioid receptor (MOR) is mainly a drug target for analgesia. Opioid-like agonists such as morphine have been clinically used for analgesia but have potential adverse effects. MOR antagonists have been demonstrated to alleviate these side effects. Plants (Carthamus tinctorius L, Cynanchum otophyllum C. K. Schneid., Coffea arabica L., Prinsepia utilis Royle and Lepidium meyenii Walp.) and Ganoderma fungi (Ganoderma hainanense J. D. Zhao, Ganoderma capense (Lloyd) Teng, Ganoderma cochlear (Blume et Nees) Bres., Ganoderma resinaceum Boud and Ganoderma applanatum (Pers.) Pat.) are traditional medicines with beneficial effects on immunoregulation, analgesia and the nervous system, but whether MORs are engaged in their effects remains unknown.

AIM OF THE STUDY

This work aimed to identify MOR ligands among compounds isolated from the above-mentioned 10 species, and to investigate selectivity against four opioid receptor subtypes. By analyzing the structure-activity relationship and off-target effects, we could provide a new direction for the future development of MOR drugs.

MATERIALS AND METHODS

Four opioid receptor subtype models, including MOR, delta (DOR), kappa (KOR) and nop (NOR), were established with a label-free phenotypic dynamic mass redistribution assay to systematically profile the pharmacological properties of known ligands. Then, 82 natural compounds derived from the 10 species were screened against MOR to identify new ligands. The selectivity of the new ligands was characterized against the four subtypes, and off-target effects were also investigated on eight G protein-coupled receptors (GPCRs).

RESULTS

The pharmacological properties of known ligands on transfected HEK293T-MOR, HEK293-DOR, HEK293-KOR and HEK293-NOR cell lines were characterized. Seven compounds purified from Ganoderma cochlear (Blume et Nees) Bres. and Carthamus tinctorius L were MOR antagonists with micromolar potency. Among them, compound 35 showed the strongest antagonistic activity on MOR with an IC₅₀ value of 10.0 ± 3.0 μM. To a certain extent, these seven new antagonists, exhibited antagonistic activity on the other opioid receptor subtypes, and they had almost no effect on other GPCRs, including CB1, CB2, M2 and beta2AR. Additionally, a compound from Lepidium meyenii Walp. displayed MOR agonistic activity.

CONCLUSIONS

The established screening models opened new avenues for the discovery and evaluation of opioid receptor ligand selectivity. Together, the novel MOR antagonists and agonists will enrich the inventory of MOR ligands and benefit related therapies.

Applanmerotic acids A and B, two meroterpenoid dimers with an unprecedented polycyclic skeleton from Ganoderma applanatum that inhibit formyl peptide receptor 2

Applanmerotic acids A and B (1 and 2) with a polycyclic skeleton isolated from Ganoderma applantum showed anti-inflammatory activity via inhibiting the activation of FPR2.