Sub-inhibitory concentrations of trans-cinnamaldehyde attenuate virulence in Cronobacter sakazakii in vitro

• Published in: International journal of molecular sciences 2014-05, Vol.15 (5), p.8639-8655
• Main Authors: Amalaradjou, Mary Anne Roshni, Kim, Kwang Sik, Venkitanarayanan, Kumar
• Format: Article
• Language: English
• Subjects: Acrolein - analogs & derivatives; Acrolein - pharmacology; Animals; Antineoplastic Agents, Phytogenic - pharmacology; Apoptosis - drug effects; Baby foods; Bacteria; Bacterial Adhesion - drug effects; Cell Line; Cronobacter sakazakii - drug effects; Cronobacter sakazakii - pathogenicity; Down-Regulation - drug effects; Endotoxins - biosynthesis; Food contamination & poisoning; Humans; Intestines - cytology; Intestines - metabolism; Intestines - microbiology; Isomerism; Macrophages - cytology; Macrophages - metabolism; Macrophages - microbiology; Microscopy, Fluorescence; Nitric Oxide Synthase Type II - antagonists & inhibitors; Nitric Oxide Synthase Type II - genetics; Nitric Oxide Synthase Type II - metabolism; Pathogens; Rats; RNA Interference; RNA, Small Interfering - metabolism; Virulence Factors - antagonists & inhibitors; Virulence Factors - genetics; Virulence Factors - metabolism
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms15058639

Cronobacter sakazakii is a foodborne pathogen, which causes a life-threatening form of meningitis, necrotizing colitis and meningoencephalitis in neonates and children. Epidemiological studies implicate dried infant formula as the principal source of C. sakazakii. In this study, we investigated the efficacy of sub-inhibitory concentrations (SIC) of trans-cinnamaldehyde (TC), an ingredient in cinnamon, for reducing C. sakazakii virulence in vitro using cell culture, microscopy and gene expression assays. TC significantly (p ≤ 0.05) suppressed C. sakazakii adhesion to and invasion of human and rat intestinal epithelial cells, and human brain microvascular endothelial cells. In addition, TC inhibited C. sakazakii survival and replication in human macrophages. We also observed that TC reduced the ability of C. sakazakii to cause cell death in rat intestinal cells, by inhibiting nitric oxide production. Results from gene expression studies revealed that TC significantly downregulated the virulence genes critical for motility, host tissue adhesion and invasion, macrophage survival, and LPS (Lipopolysaccharide) synthesis in C. sakazakii. The efficacy of TC in attenuating these major virulence factors in C. sakazakii underscores its potential use in the prevention and/or control of infection caused by this pathogen.