Atomic force microscopy study of ionomycin-induced degranulation in RBL-2H3 cells

Current utilization trend of immortalized mast cell lines in allergy research: a systematic review

Today, in the modern world, allergic diseases, also described as atopic allergies, are classified as a type of multifactorial disorder due to the complex interplay between genetics, environment, and socioeconomic factors that influence the disease's manifestation, severity, and one's predisposition to allergic diseases. It is undeniable that many reported studies have pointed out that the mast cell is one of the leading key players involved in triggering an allergic reaction. To improve our understanding of the molecular and cellular mechanisms underlying allergy, various mast cell lines have been employed in vitro to study the pathogenesis of allergic diseases for the past decades. However, there is no consensus on many fundamental aspects associated with their use, such as the effects of culture media composition and the type of inducer used for cell degranulation. As the standardization of research protocols and disease models is crucial, we present the outcome of a systematic review of scientific articles using three major immortalized in vitro mast cell lines (HMC-1, LAD2, and RBL-2H3) to study allergy. This systematic review described the cell source, culture conditions, inducers used for degranulation, and mediators released for examination. We hope that the present systematic review may help to standardize the use of immortalized in vitro mast cell lines in allergy research and serve as a user's guide to understand the fundamental aspects of allergy as well to develop an effective allergy therapy in the future for the betterment of human good health and wellbeing.

Traditional cooking methods decreased the allergenicity of egg proteins

Egg allergy is one of the most common food allergies globally. This study aimed to assess the impact of four traditional cooking methods on the allergenicity of egg proteins using a comprehensive strategy, including simulated gastrointestinal digestion in vitro, serology experiments, a rat basophilic leukemia (RBL)-2H3 cell degranulation model, and a passive cutaneous anaphylaxis (PCA) mice model, and the structure changes were detected by circular dichroism (CD) spectra and ultraviolet (UV) spectra. The results showed that the processed egg proteins were more readily digested compared to raw egg proteins. The serological experiments revealed a significant reduction in immunoglobulin E binding of egg proteins after thermal treatments (p < 0.05), particularly after frying. Subsequently, the RBL-2H3 cell degranulation experiment demonstrated a marked decrease in the level of egg allergens-induced β-hexosaminidase release after cooking (p < 0.05). Moreover, the results from the PCA mice model indicated that the increase in vascular permeability was effectively relieved in the treated groups, especially in frying group (p < 0.05). Additionally, the α-helix and β-turn contents of processed egg proteins were significantly decreased (p < 0.05) compared with native egg proteins. The UV spectra findings showed that all cooking treatments caused significant alterations in the tertiary structure, and fluorescence analysis indicated that cooking decreased the surface hydrophobicity of egg proteins. In conclusion, four traditional cooking methods reduced the allergenicity of egg proteins, particularly frying, and this reduction was associated with structural changes that could contribute to the destruction or masking of epitopes of egg allergens. PRACTICAL APPLICATION: Egg allergy has a serious impact on public health, and there is no ideal treatment method at present. This study demonstrated that four traditional cooking methods (boiling, steaming, baking, and frying) reduced the allergenicity of egg proteins, especially frying, and the results will provide a basis for the development of hypoallergenic egg products.

Hypersensitivity reactions to small molecule drugs

Drug hypersensitivity reactions induced by small molecule drugs encompass a broad spectrum of adverse drug reactions with heterogeneous clinical presentations and mechanisms. These reactions are classified into allergic drug hypersensitivity reactions and non-allergic drug hypersensitivity reactions. At present, the hapten theory, pharmacological interaction with immune receptors (p-i) concept, altered peptide repertoire model, and altered T-cell receptor (TCR) repertoire model have been proposed to explain how small molecule drugs or their metabolites induce allergic drug hypersensitivity reactions. Meanwhile, direct activation of mast cells, provoking the complement system, stimulating or inhibiting inflammatory reaction-related enzymes, accumulating bradykinin, and/or triggering vascular hyperpermeability are considered as the main factors causing non-allergic drug hypersensitivity reactions. To date, many investigations have been performed to explore the underlying mechanisms involved in drug hypersensitivity reactions and to search for predictive and preventive methods in both clinical and non-clinical trials. However, validated methods for predicting and diagnosing hypersensitivity reactions to small molecule drugs and deeper insight into the relevant underlying mechanisms are still limited.

The effects and the mechanisms of naringenin from Artemisia ordosica Krasch on allergic rhinitis based on mast cell degranulation model and network pharmacology

OBJECTIVES

The ethyl acetate extraction of Artemisia ordosica Krasch (AOK) root showed anti-allergic rhinitis (AR) effect, while the active compounds and pharmacological targets were unknown.

METHODS

The P815 degranulation was established by cell counting kit 8 assay, β-hexosaminidase releasing assay and toluidine blue staining. The flavonoids were screened in vitro. Then toluidine blue staining and ELISA were carried out to investigate the anti-inflammatory effects of the active compound. Network pharmacology was implemented to explain the mechanisms of the active compound. iGEMDOCK was used to investigate the binding between active compound and hub targets.

KEY FINDINGS

C48/80 was the optimum reagent in triggering P815 degranulation. Naringenin could significantly decrease P815 degranulation. Meanwhile, naringenin could remarkably increase the IL-4 and decrease the tumour necrosis factor-α. The effect of naringenin on AR was achieved by regulating multiple targets (e.g. AKT1, MAPK3, VEGFA) and pathways (e.g. pathways in cancer, VEGF signalling pathway). Nine hub proteins were obtained by topological analysis. Multiple hydrogen bonds and van der Waals forces were formed between the naringenin and the residues of hub proteins.

CONCLUSIONS

Naringenin might be one of the effective ingredients of AOK against AR. And its effects could achieve through regulating multiple targets and pathways.

Inhibitory activity of narirutin on RBL-2H3 cells degranulation

Context: It is an efficient strategy to apply inhibition of mast cell degranulation for evaluating anti-allergic effects of compounds. Previous works confirmed that narirutin had anti-allergic activity in OVA induced allergic asthma murine model. However, the mechanism is not clear. Objective: Here, inhibitory mechanism of narirutin on RBL-2H3 cells degranulation was investigated. Materials and methods: Cell viability was analyzed by CCK-8 kits, cell degranulation was analyzed by ELISA methods, morphology and ultrastructure of cells was observed by atomic force microscopy, intracellular Ca ²⁺ concentration was measured by fluorescence microscopre, mRNA expression were measured by PCR, and signaling pathways were measured by WB. Results: The results showed that narirutin have no direct effects on mRNA expression of FcεRI subunit. However, it inhibited Ca²⁺ influx by suppressing the phosphorylation of Syk, LAT and PLCγ1 signaling pathway transduction. Subsequently, the inhibition of Ca²⁺ influx directly leads to NF-κB signaling pathway transduction decreased. Narirutin can also suppress the phosphorylation of MAPK signaling pathways by decreasing the expression of P-p38, P-ERK and P-JNK, inhibit the synergistic effect for Ca²⁺ influx, and then reduce the release of IL-4, TNF-α, histamine and β-HEX. Conclusion: Our study suggested that the inhibitory mechanism of narirutin on RBL-2H3 cells degranulation could be related to regulate MAPK, NF-κB and Tyrosine kinase signaling pathway.

A rapid and sensitive assay based on particle analysis for cell degranulation detection in basophils and mast cells

The degranulation of mast cells and basophils is often initiated by a number of pathophysiological responses, especially in allergic and inflammatory conditions. Efficient techniques and methods for determining the level of such degranulation are highly demanded for laboratory and clinical studies. In this work, a rapid and sensitive assay based on the particle analysis of granules in RBL-2H3 cells, a cell line widely used as a convenient model system to study the degranulation of mast cells and basophils, was developed to detect cell degranulation using a Nanosight NS300 in light scatter mode and dynamic light scattering (DLS) on a Malvern Zetasizer Nano-ZS instrument. Using this method, drug-induced mast cell degranulation and systemic anaphylaxis were efficiently determined both in cell culture medium and blood samples from animals in the current study. This promising method is expected to be widely used for screening anti-allergic and anti-inflammatory drugs both in vitro and in vivo models, as well as for determining the level of mast cell degranulation of the patients in the clinic.