Plakoglobin and High-Mobility Group Box 1 Mediate Intestinal Epithelial Cell Apoptosis Induced by Clostridioides difficile TcdB

Deciphering the pharmacological mechanisms of Shenlingbaizhu formula in antibiotic-associated diarrhea treatment: Network pharmacological analysis and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Shenlingbaizhu (SLBZ) formula, a classical traditional Chinese medicinal (TCM) formula, has been widely used for treating antibiotic-associated diarrhea (AAD). However, the underlying pharmacological mechanisms have not yet been investigated thoroughly.

AIM OF THE STUDY

To explore the remission mechanism of SLBZ in the treatment of AAD, we conducted network pharmacological analysis and experimental validation in vitro and in vivo.

MATERIALS AND METHODS

In this study, the main compounds of SLBZ were identified by ultra-high-performance liquid chromatography-mass spectroscopy (UHPLC-MS) and online databases. The targets of the active components and AAD-related targets were predicted by network pharmacology, and the potential targets of SLBZ against AAD were obtained. Then the core targets were recognized after Protein-Protein Interaction (PPI) analysis. Based on these, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analyses were conducted, and the key pathway was screened. Subsequently, molecular docking was performed using Auto Dock Vina to find the key components that played a crucial role in that pathway. Molecular dynamics simulation was performed by Gromacs software to detect the binding mode. Finally, the results were confirmed by in vitro and in vivo experiments.

RESULTS

A total of 66 active ingredients of SLBZ were detected by UHPLC-MS, and 128 active ingredients were screened out by network pharmacological analysis. Additionally, 935 drug targets and 1686 AAD-related targets were obtained. Seventy-eight intersected genes were selected as potential therapeutic targets and 19 genes were excavated as core targets. Enrichment analysis revealed PI3K-AKT signaling pathway was the key pathway in SLBZ against AAD. Topological analysis further revealed that JAK2, MTOR, TLR4, and SYK were the key targets affected by SLBZ on the PI3K-AKT pathway, and 52 components of SLBZ were associated with them. Molecular docking and dynamics simulation revealed strong binding affinities between MTOR and diosgenin. Subsequently, after SLBZ treatment, the expression levels of JAK2, MTOR, TLR4, and SYK were found significantly upregulated in the AAD model rats (p < 0.05). The cell experiment further validated the good binding ability between MTOR and diosgenin.

CONCLUSION

We demonstrate that the therapeutic effect of SLBZ on AAD was achieved in part by inhibiting the PI3K-AKT pathway.

Exploring the Toxin-Mediated Mechanisms in Clostridioides difficile Infection

Clostridioides difficile infection (CDI) is the leading cause of nosocomial antibiotic-associated diarrhea, and colitis, with increasing incidence and healthcare costs. Its pathogenesis is primarily driven by toxins produced by the bacterium C. difficile, Toxin A (TcdA) and Toxin B (TcdB). Certain strains produce an additional toxin, the C. difficile transferase (CDT), which further enhances the virulence and pathogenicity of C. difficile. These toxins disrupt colonic epithelial barrier integrity, and induce inflammation and cellular damage, leading to CDI symptoms. Significant progress has been made in the past decade in elucidating the molecular mechanisms of TcdA, TcdB, and CDT, which provide insights into the management of CDI and the future development of novel treatment strategies based on anti-toxin therapies. While antibiotics are common treatments, high recurrence rates necessitate alternative therapies. Bezlotoxumab, targeting TcdB, is the only available anti-toxin, yet limitations persist, prompting ongoing research. This review highlights the current knowledge of the structure and mechanism of action of C. difficile toxins and their role in disease. By comprehensively describing the toxin-mediated mechanisms, this review provides insights for the future development of novel treatment strategies and the management of CDI.

An Updated View on the Cellular Uptake and Mode-of-Action of Clostridioides difficile Toxins

Research on the human gut pathogen Clostridioides (C.) difficile and its toxins continues to attract much attention as a consequence of the threat to human health posed by hypervirulent strains. Toxin A (TcdA) and Toxin B (TcdB) are the two major virulence determinants of C. difficile. Both are single-chain proteins with a similar multidomain architecture. Certain hypervirulent C. difficile strains also produce a third toxin, namely binary toxin CDT (C. difficile transferase). C. difficile toxins are the causative agents of C. difficile-associated diseases (CDADs), such as antibiotics-associated diarrhea and pseudomembranous colitis. For that reason, considerable efforts have been expended to unravel their molecular mode-of-action and the cellular mechanisms responsible for their uptake. Many of these studies have been conducted in European laboratories. Here, we provide an update on our previous review (Papatheodorou et al. Adv Exp Med Biol, 2018) on important advances in C. difficile toxins research.