Ethnopharmacological relevance: Coptidis rhizoma, first recorded in the "Shen Nong's Herbal Classic", is one of the traditional Chinese medicine (TCM) used to treat infectious diseases, with reputed effectiveness against oropharyngeal candidiasis (OPC). Studies have demonstrated the inhibitory properties of C. rhizoma (CRE) against Candida albicans, yet there is limited information available regarding its treatment mechanism for OPC.
Aim of the study: Our previous research has suggested that CRE can prevent the formation of C. albicans hyphae and their invasion of the oral mucosa, thereby exerting a therapeutic effect on OPC. Nevertheless, the precise therapeutic mechanisms remain incompletely understood. Previous studies have revealed that a receptor for globular heads of C1q (gC1qR), a crucial co-receptor of the epidermal growth factor receptor (EGFR), facilitates the EGFR-mediated internalization of C. albicans. Therefore, this study aims to investigate the potential mechanism of action of CRE and its primary component, berberine (BBR), in treating OPC by exploring their effects on the gC1qR-EGFR co-receptor.
Materials and methods: To identify the chemical components of CRE, we utilized Ultra-high performance liquid chromatography in conjunction with quadrupole time-of-flight mass spectrometry (UPLC-Q/TOF-MSE), revealing the presence of at least 18 distinct components. To observe the therapeutic effects of CRE on OPC at the animal level, we employed hematoxylin and eosin staining, periodic acid-Schiff staining, scanning electron microscopy, and fungal load detection. Subsequently, we evaluated the anti-inflammatory properties of CRE and its main component, BBR, in treating OPC. This was achieved through enzyme-linked immunosorbent assay (ELISA) both at the animal and cellular levels. Additionally, we assessed the ability of C. albicans to disrupt the epithelial barrier of FaDu cells by studying the protective effects of BBR on the fusion barrier using the transwell assay. To further explore the underlying mechanisms, we analyzed the effects of BBR on the gC1qR-EGFR/extracellular signal-regulated kinase/c-Fos signaling pathway at the cellular level using qRT-PCR, western blotting, and immunofluorescence. Furthermore, we validated the effects of BBR on the gC1qR-EGFR co-receptor through ELISA, qRT-PCR, and western blotting. Finally, to confirm the outcomes observed at the cellular level, we validated the impact of CRE on the gC1qR-EGFR co-receptor in vivo using qRT-PCR, western blotting, and immunofluorescence. These comprehensive methods allowed us to gain a deeper understanding of the therapeutic mechanisms of CRE and BBR in treating OPC.
Results: Our findings indicate that CRE and its primary component, BBR, effectively alleviated the symptoms of OPC by modulating the gC1qR-EGFR co-receptor. The chemical composition of CRE and BBR was accurately identified using UPLC-Q/TOF-MSE. The gC1qR-EGFR co-receptor plays a crucial role in regulating downstream signaling pathways, emerging as a potential therapeutic target for OPC treatment. Through both in vitro and in vivo experiments, we explored the therapeutic potential of CRE and BBR in OPC. Additionally, we employed overexpression and silencing techniques to confirm that BBR can indeed influence the gC1qR-EGFR co-receptor and regulate the gC1qR-EGFR/extracellular signal-regulated kinase (ERK)/c-Fos signaling pathway, leading to improved OPC outcomes. Furthermore, the significance of CRE's effect on the gC1qR-EGFR co-receptor was validated in vivo.
Conclusion: Our study demonstrates that CRE and its main component, BBR, can effectively alleviate OPC symptoms by targeting the gC1qR-EGFR heterodimer receptor. This discovery offers a promising new therapeutic approach for the treatment of OPC.
Keywords: Berberine; Candida albicans; Coptidis rhizoma extract; Oropharyngeal candidiasis; gC1qR-EGFR/ERK/c-Fos axis.
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