Licochalcone A inhibits MAS-related GPR family member X2-induced pseudo-allergic reaction by suppressing nuclear migration of nuclear factor-κB.

Licochalcone A (Lico A) is a natural flavonoid belonging to the class of substituted chalcone that has various biological effects. Mast cells (MCs) are innate immune cells that mediate hypersensitivity and pseudo-allergic reactions. MAS-related GPR family member X2 (MRGPRX2) on MCs has been recognized as the main receptor for pseudo-allergic reactions. In this study, we investigated the anti-pseudo-allergy effect of Lico A and its underlying mechanism. Substance P (SP), as an MC activator, was used to establish an in vitro and in vivo model of pseudo-allergy. The in vivo effect of Lico A was investigated using passive cutaneous anaphylaxis (PCA) and active systemic allergy, along with degranulation, Ca2+ influx in vitro. SP-induced laboratory of allergic disease 2 (LAD2) cell mRNA expression was explored using RNA-seq, and Lico A inhibited LAD2 cell activation by reverse transcription polymerase chain reaction (RT-PCR), western blotting, and immunofluorescence staining. Lico A showed an inhibitory effect on SP-induced MC activation and pseudo-allergy both in vitro and in vivo. The nuclear factor (NF)-κB pathway is involved in MRGPRX2 induced MC activation, which is inhibited by Lico A. In conclusion, Lico A inhibited the pseudo-allergic reaction mediated by MRGPRX2 by blocking NF-κB nuclear migration.

Baicalin induces Mrgprb2-dependent pseudo-allergy in mice.

Baicalin, a component of traditional Chinese medicine, is one of the main compounds present in Scutellaria baicalensis Georgi. Pseudo-allergy induced by the injection of these medicines is a frequent adverse drug reaction. Therefore, elucidation of the anaphylactoid reaction of baicalin and its underlying mechanisms are important. Mast cells are primary effectors of allergic reactions, including pseudo-allergy. Studies have shown that Mrgprx2 in human mast cells is a specific receptor that is crucial for pseudo-allergic drug reactions, Mrgprb3 is the rat ortholog of human Mrgprx2, which in mice is designated as Mrgprb2. Here, we aimed to investigate baicalin-induced pseudo-allergy and the association of Mrgprb3 and Mrgprb2 with this effect. We examined the allergenic effect of baicalin on RBL-2H3 cells and Mrgprb3-knockdown RBL-2H3 cells. Mrgprb2-expressing HEK293 cells and Mrgprb2-knockout mice were used to evaluate the role of Mrgprb2 in baicalin-induced allergy. Baicalin was found to dose-dependently induce pseudo-allergy both in vitro and in vivo. RBL-2H3 cells were activated by baicalin, whereas in Mrgprb3-knockout RBL-2H3 cells, baicalin showed a negligible effect on cell activation. Furthermore, baicalin activated the Mrgprb2-expressing HEK293 cells. Our data showed that baicalin did not induce allergy in Mpgprb2-knockout mice. We conclude that baicalin induces pseudo-allergy via Mrgprb2 in mice.

Isoimperatorin reduces the effective dose of dexamethasone in a murine model of asthma by inhibiting mast cell activation.

Adverse effects that result from dexamethasone (DEX) use are common and serious in patients with asthma. Therefore, alternative anti-inflammatory treatments are being investigated. Isoimperatorin (ISO), an active natural furocoumarin, possesses multiple pharmacological properties, including an anti-inflammation effect. In this study, investigations were conducted on the effect of ISO on mast cell (MC) activation in vitro and whether ISO could reduce the effective dose of DEX in a mast cell-dependent murine model of asthma in vivo. Calcium imaging was used to assess intracellular Ca2+ mobilization. Enzyme-linked immunosorbent assay was used to measure the chemokines release. Western blot analysis was conducted to investigate the underlying pathway. Airway inflammation and hyperresponsiveness (AHR) were examined in an asthma model. ISO inhibited Ca2+ flux and MC degranulation via Lyn/PLCγ1/PKC, ERK, and P38 MAPK pathways. In the asthma model, ISO, in combination with DEX, showed an additive inhibitory effect on AHR, inflammation, and the number of activated MCs in the lungs and decreased the levels of interleukin (IL)-4, IL-5, IL-6, IL-13, tumor necrosis factor (TNF)-a, and C-C motif chemokine ligand (CCL)-2 in bronchoalveolar lavage fluid. A combination of DEX and ISO may be appropriate if a decrease in the steroid dose is desired owing to dose-dependent adverse effects.

Discovery and analysis the anti-pseudo-allergic components from Perilla frutescens leaves by overexpressed MRGPRX2 cell membrane chromatography coupled with HPLC-ESI-IT-TOF system.

OBJECTIVES: Screen and identify the anti-pseudo-allergic activity components of Perilla frutescens leaves that interacted with MRGPRX2 (a new reported pseudo-allergic reaction-related receptor). METHODS: An overexpressed MRGPRX2 cell membrane chromatography (CMC) coupled with HPLC-ESI-IT-TOF system has been established to screen and identify the effective components from P. frutescens leaves. A frontal analysis method was performed to investigate the binding affinity between ligands and MRGPRX2. Their activity of relieving pseudo-allergic reaction was evaluated in vitro by histamine release assay, ß-hexosaminidase release assay and intracellular Ca2+ mobilization assay. KEY FINDINGS: Extract of P. frutescens leaves was proved to be effective in anti-pseudo-allergic reaction by inhibiting MRGPRX2. Apigenin (API) and rosmarinic acid (ROS) were confirmed to be the potential anti-allergy compounds that could bind with MRGPRX2. The binding affinity (KD ) of ROS and API with MRGPRX2 was (8.79 ± 0.13) × 10-8  m and (6.54 ± 1.69) × 10-8  m, respectively. The IC50 of API inhibiting laboratory of allergic disease 2 cells degranulation was also determined to be (51.96 ± 0.18) µm. CONCLUSIONS: A MRGPRX2/CMC coupled with HPLC-ESI-IT-TOF system was successfully established and applied to discover the effective components from P. frutescens leaves.

The anti-inflammation effect of Baige capsule and its principal components mixture in MCAO rats.

BACKGROUND: Baige (BG) is a compound Chinese herbal preparation, constituted of different position extracts (ethanol extracts from Pueraria lobate and SFE-CO2 extracts from Radix Angelicae dahuricae) of P. lobata and A. dahurica to treat the brain injury in patients. AIM: The goal of this study was to identify the neuroprotective properties of BG and its principal component mixture (PCM) and verify whether the material basis for BG is its PCM. METHODS: Middle cerebral artery occlusion (MCAO) was operated on male Sprague-Dawley rat for 2 h, different doses of BG or PCM or vehicle were gavaged after 3 h of MCAO. Rats were sacrificed after 30 days treatment. Blood serum inflammation factors and NGF were detected by ELISA. RESULTS: After 30 days of treatment, both BG and PCM interventions reduced the infarct volume, modified neurological severity score (mNSS) in rats, declined IL-1ß and IL-6 levels in the serum, increased NGF level in the serum and recovered the number of Nissl body in injured brain. CONCLUSIONS: Both BG and PCM exert equivalent levels of recovery effect in MCAO on rats; and PCM is the material foundation of BG. This recovery effect is associated with inflammatory inhibition and NGF production.