Inhibitory Effects of Anthocyanins on Secretion of Helicobacter pylori CagA and VacA Toxins

Abstract

Anthocyanins have been studied as potential antimicrobial agents against Helicobacter pylori. We investigated whether the biosynthesis and secretion of cytotoxin-associated protein A (CagA) and vacuolating cytotoxin A (VacA) could be suppressed by anthocyanin treatment in vitro. H. pylori reference strain 60190 (CagA+/VacA+) was used in this study to investigate the inhibitory effects of anthocyanins; cyanidin 3-O-glucoside (C3G), peonidin 3-O-glucoside (Peo3G), pelargonidin 3-O-glucoside (Pel3G), and malvidin 3-O-glucoside (M3G) on expression and secretion of H. pylori toxins. Anthocyanins were added to bacterial cultures and Western blotting was used to determine secretion of CagA and VacA. Among them, we found that C3G inhibited secretion of CagA and VacA resulting in intracellular accumulation of CagA and VacA. C3G had no effect on cagA and vacA expression but suppressed secA transcription. As SecA is involved in translocation of bacterial proteins, the down-regulation of secA expression by C3G offers a mechanistic explanation for the inhibition of toxin secretion. To our knowledge, this is the first report suggesting that C3G inhibits secretion of the H. pylori toxins CagA and VacA via suppression of secA transcription.

Cyanidin 3-O-Glucoside Reduces Helicobacter pylori VacA-Induced Cell Death of Gastric KATO III Cells through Inhibition of the SecA Pathway

“…We found that the levels of both secreted VacA was decreased when bacteria were cultured with C3G starting a 12.5 μM of C3G and this decrease was more pronounced proportionately to increases in C3G concentration (Figure 1A). Consistent with previous results21, the bacterial numbers were unchanged by C3G treatment at all concentrations compared to mock-treated bacteria suggesting that the decrease in secreted VacA was not due to a decrease in bacterial cell numbers (data not shown). The levels of total secreted proteins were similar at all concentrations of C3G used as determined by reactivity to rabbit anti- H. pylori polyclonal antibody showing that the decrease in VacA was specific to C3G treatment (Figure 1A and B).…”

“…In our previous report we showed that C3G inhibited secA transcription21. SecA is an intracellular protein that facilitates translocation of bacterial proteins out of the bacterial plasma membrane19.…”

Regulatory Effects of Black Rice Extract on Helicobacter pylori Infection‐Induced Apoptosis

“…However, C3G and BRE exert different effects on H. pylori . In our previous study, we found that purified C3G did not affect the expression of vacA and cagA but inhibited the secretion of VacA and CagA by downregulating secA expression . However, in the present study, we found that BRE downregulated vacA and cagA transcription and inhibited VacA secretion.…”

“…Five independent cDNA samples were analyzed. Primer sequences and PCR conditions used for amplifying cagA , vacA , secA , and galE have been described previously . Primer sequences and PCR conditions used for amplifying the T4SS components are described in Table .…”

Phenolic Composition and Evaluation of the Antimicrobial Activity of Free and Bound Phenolic Fractions from a Peruvian Purple Corn (Zea mays L.) Accession

“…Only few studies have reported the antimicrobial action of anthocyanins against H. pylori . Kim and others () determined that a dose of 0.045 mg cyanidin‐3‐glucoside/mL (similar or lower than ranges used in the current study: 0.03 to 0.15 mg cyanidin‐3‐glucose equivalents/disk) did not show any effect on H. pylori bacterial number; however, H. pylori virulence factors such as cytotoxin‐associated protein A (CagA) and vacuolating cytotoxin A (VacA) decreased. The pretreatment of human gastric epithelial cell lines with anthocyanins isolated from soybean coat in a range of 0.0125 to 0.05 mg/mL (similar or lower than ranges used in this study) decreased the H. pylori ‐induced inflammation markers such as reactive oxygen species (ROS) and interleukin‐8, and inhibited the H. pylori‐ induced inducible nitric oxide synthases and cyclooxygenase‐2 mRNA expression (Kim and others ).…”