Equol inhibits growth and spore formation of Clostridioides difficile

Fighting against Clostridioides difficile infection: Current medications

Clostridioides difficile (formerly Clostridium difficile) has been regarded as an "urgent threat" and a significant global health problem, as life-threatening diarrhea and refractory recurrence are common in patients with C. difficile infection (CDI). Unfortunately, the available anti-CDI drugs are limited. Recent guidelines recommend fidaxomicin and vancomycin as first-line drugs to treat CDI, bezlotoxumab to prevent recurrence, and fecal microbiota transplantation (FMT) for rescue treatment. Currently, researchers are investigating therapeutic antibacterial drugs (e.g., teicoplanin, ridinilazole, ibezapolstat, surotomycin, cadazolid, and LFF571), preventive medications against recurrence (e.g., Rebyota, Vowst, VP20621, VE303, RBX7455, and MET-2), primary prevention strategies (e.g., vaccine, ribaxamase, and DAV132) and other anti-CDI medications in the preclinical stage (e.g., Raja 42, Myxopyronin B, and bacteriophage). This narrative review summarizes current medications, including newly marketed drugs and products in development against CDI, to help clinicians treat CDI appropriately and to call for more research on innovation.

Pantoprazole promotes sustained intestinal carriage of multidrug-resistant Escherichia coli in amoxicillin-treated mice

AIMS

The main objective of this study was to compare extended-spectrum β-lactamase (ESBL) Escherichia coli fecal titers during 12 days between two groups: mice who received proton pump inhibitors (PPIs) and those that did not.

METHODS AND RESULTS

We tested three different in vivo models: model 1, high inoculum (106 CFU ml-1); model 2, low inoculum (102 CFU ml-1); and model 3, low inoculum and 2-day amoxicillin wash-out. There was no significant difference between the two groups in fecal ESBL E. coli titers in models 1 and 2. The fecal titers of ESBL E. coli were probably too high to show differences in colonization related to PPI treatment. By introducing a 2-day wash-out period after stopping amoxicillin (model 3), the fecal ESBL E. coli titers were higher in the PPI-treated mice during 12 days (3 log versus 11 log day CFU g-1; P < 0.05). This result highlighted that PPIs promote stable ESBL E. coli digestive carriage in mice. Fecal quantitative PCR showed that mice with low ESBL E. coli fecal titers had a much higher concentration of equol-producing bacteria, Muribaculum sp., and Adlercreutzia caecimuris.

CONCLUSIONS

Pantoprazole treatment promotes sustained digestive carriage of ESBL E. coli in amoxicillin-treated mice.

Genistein Inhibits Clostridioides difficile Infection via Estrogen Receptors and Lysine-Deficient Protein Kinase 1

BACKGROUND

Clostridioides difficile infection (CDI) is a debilitating nosocomial disease. Postmenopausal women may have an increased risk of CDI, suggesting estrogen influence. Soybean products contain a representative estrogenic isoflavone, genistein.

METHODS

The anti-inflammatory and antiapoptotic effects of genistein were determined using primary human cells and fresh colonic tissues. The effects of oral genistein therapy among mice and hamsters were evaluated.

RESULTS

Within 10 days of CDI, female c57BL/6J mice in a standard environment (regular diet) had a 50% survival rate, while those with estrogen depletion and in an isoflavone-free environment (soy-free diet) had a 25% survival rate. Oral genistein improved their 10-day survival rate to 100% on a regular diet and 75% in an isoflavone-free environment. Genistein reduced macrophage inflammatory protein-1α (MIP-1α) secretion in fresh human colonic tissues exposed to toxins. Genistein inhibited MIP-1α secretion in primary human peripheral blood mononuclear cells, abolished apoptosis and BCL-2-associated X (BAX) expression in human colonic epithelial cells, and activated lysine-deficient protein kinase 1 (WNK1) phosphorylation in both cell types. The anti-inflammatory and antiapoptotic effects of genistein were abolished by inhibiting estrogen receptors and WNK1.

CONCLUSIONS

Genistein reduces CDI disease activity by inhibiting proinflammatory cytokine expression and apoptosis via the estrogen receptor/G-protein estrogen receptor/WNK1 pathways.

Anti-bacterial and Anti-biofilm Effects of Equol on Yersinia enterocolitica

Yersinia enterocolitica has clinical significance due to its etiological role in yersiniosis and gastroenteritis. This study was designed to assess anti-bacterial and anti-biofilm effects of equol on Y. enterocolitica via phenotypic and genetic analyses. To determine its anti-bacterial activity, minimum inhibitory concentrations (MICs) of equol against clinically isolated Y. enterocolitica strains were analyzed. Subsequently, it was confirmed that the sub-MIC90 value of equol could inhibit biofilm formation and reduce preformed biofilm. Furthermore, it was found that equol could reduce the expression of biofilm-related (hmsT) gene in Y. enterocolitica. This study also demonstrated that equol not only reduced levels of bacterial motility, but also decreased the expression of a motility-related (flhDC) gene in Y. enterocolitica. XTT [2,3-bis (2-metoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction analysis revealed that equol attenuated cellular metabolic activities in Y. enterocolitica biofilm. Additionally, changes in biomass and cell density in equol-treated biofilms were visualized using a confocal laser scanning microscope. In conclusion, this study suggests that equol is a potential anti-bacterial and anti-biofilm agent to treat Y. enterocolitica.

Biocatalytic synthesis and evaluation of antioxidant and antibacterial activities of hydroxyequols

Hydroxyequols are promising analogues of the biologically active flavonoid, equol. We recently found that the flavin-dependent monooxygenase HpaB_ro-3 of Rhodococcus opacus regioselectively synthesizes 3'-hydroxyequol from equol, whereas HpaB_pl-1 of Photorhabdus luminescens synthesizes 6-hydroxyequol. In this study, we investigated the cascade synthesis of a dihydroxyequol compound from equol using these two enzymes. When Escherichia coli cells expressing HpaB_ro-3 and cells expressing HpaB_pl-1 were simultaneously incubated with equol, the cells efficiently synthesized 6,3'-dihydroxyequol (8.7 mM, 2.4 g/L) via 3'- and 6-hydroxyequols in one pot. The antioxidant activity of the equol derivatives increased with an increase in the number of hydroxyl groups on the equol scaffold. 6,3'-Dihydroxyequol exhibited potent antioxidant activity. In addition, 6-hydroxyequol significantly inhibited the growth of E. coli. Cell survival studies suggested that 6-hydroxyequol is a bactericidal rather than bacteriostatic compound. To our knowledge, this is the first report describing the antibacterial activity of hydroxyequols.

Characterization and Identification of a New Daidzein Reductase Involved in (S)-Equol Biosynthesis in Clostridium sp. ZJ6

(S)-equol (EQ) is an isoflavone with high estrogen-like activity in the human body, and is only produced by some gut bacteria in vivo. It plays an important role in maintaining individual health, however, the dearth of resources associated with (S)-EQ-producing bacteria has seriously restricted the production and application of (S)-EQ. We report here a new functional gene KEC48-07020 (K-07020) that was identified from a chick (S)-EQ-producing bacterium (Clostridium sp. ZJ6, ZJ6). We found that recombinant protein of K-07020 possessed similar function to daidzein reductase (DZNR), which can convert daidzein (DZN) into R/S-dihydrodaidzein (R/S-DHD). Interestingly, K-07020 can reversely convert (R/S)-DHD (DHD oxidase) into DZN even without cofactors under aerobic conditions. Additionally, high concentrations of (S)-EQ can directly promote DHD oxidase but inhibit DZNR activity. Molecular docking and site-directed mutagenesis revealed that the amino acid > Arg75 was the active site of DHD oxidase. Subsequently, an engineered E. coli strain based on K-07020 was constructed and showed higher yield of (S)-EQ than the engineered bacteria from our previous work. Metagenomics analysis and PCR detection surprisingly revealed that K-07020 and related bacteria may be prevalent in the gut of humans and animals. Overall, a new DZNR from ZJ6 was found and identified in this study, and its bidirectional enzyme activities and wide distribution in the gut of humans and animals provide alternative strategies for revealing the individual regulatory mechanisms of (S)-EQ-producing bacteria.

The role of flavonoids in inhibiting IL-6 and inflammatory arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that primarily affects the synovial joints. RA has well-known clinical manifestations and can cause progressive disability and premature death along with socioeconomic burdens. Interleukin-6 (IL-6) has been implicated in the pathology of RA where it can stimulate pannus formation, osteoclastogenesis, and oxidative stress. Flavonoids are plant metabolites with beneficial pharmacological effects, including anti-inflammatory, antioxidant, antidiabetic, anticancer, and others. Flavonoids are polyphenolic compounds found in a variety of plants, vegetables, and fruits. Many flavonoids have demonstrated anti-arthritic activity mediated mainly through the suppression of pro-inflammatory cytokines. This review thoroughly discusses the accumulate data on the role of flavonoids on IL-6 in RA.

Synergistic Activity of Equol and Meropenem against Carbapenem-Resistant Escherichia coli

The emergence of carbapenem-resistant Enterobacterales (CRE) seriously limits treatment options for bacterial infections. Combined drugs are an effective strategy to treat these resistant strains. This study aimed to evaluate the synergistic effect of equol and meropenem against carbapenem-resistant Escherichia coli. First, this study investigated the antibacterial activity of carbapenems on clinically isolated E. coli strains by analyzing the minimum inhibitory concentrations (MICs). The E. coli strains were all resistant to carbapenem antibiotics. Therefore, we confirmed the cause of carbapenem resistance by detecting bla_KPC and bla_OXA-48 among the carbapenemase genes using polymerase chain reaction (PCR) analysis. Checkerboard and time-kill analyses confirmed that equol restored the susceptibility of carbapenem-resistant E. coli to meropenem. Also, the transcription levels of specific carbapenemase genes in E. coli were significantly suppressed by equol. The study also evaluated the anti-virulence effects of equol on bacterial biofilm and motility through phenotypic and genotypic analyses. In conclusion, our results revealed that equol had a synergistic effect with meropenem on carbapenem-resistant E. coli. Therefore, this study suggests that equol is a promising antibiotic adjuvant that prevents the expression of carbapenemases and virulence factors in carbapenem-resistant E. coli.

Microbial Metabolites Determine Host Health and the Status of Some Diseases

The gastrointestinal (GI) tract is a highly complex organ composed of the intestinal epithelium layer, intestinal microbiota, and local immune system. Intestinal microbiota residing in the GI tract engages in a mutualistic relationship with the host. Different sections of the GI tract contain distinct proportions of the intestinal microbiota, resulting in the presence of unique bacterial products in each GI section. The intestinal microbiota converts ingested nutrients into metabolites that target either the intestinal microbiota population or host cells. Metabolites act as messengers of information between the intestinal microbiota and host cells. The intestinal microbiota composition and resulting metabolites thus impact host development, health, and pathogenesis. Many recent studies have focused on modulation of the gut microbiota and their metabolites to improve host health and prevent or treat diseases. In this review, we focus on the production of microbial metabolites, their biological impact on the intestinal microbiota composition and host cells, and the effect of microbial metabolites that contribute to improvements in inflammatory bowel diseases and metabolic diseases. Understanding the role of microbial metabolites in protection against disease might offer an intriguing approach to regulate disease.