Evaluation of the effect of curcumin on the expression of AHA_۰۹۸ and AHA_۳۸۵۷ genes in Aeromonas hydrophila

Background and Aim : Aeromonas hydrophila is a Gram-negative bacterium able to infect a variety of aquatic and terrestrial animals, including humans. In humans, it can cause bacteremia, gastroenteritis, meningitis and peritonitis. Pathogenesis of A.hydrophila is multifactorial. The involvement of AHA_۳۸۵۷ and AHA_۰۹۸ genes, the genes responsible for bacterial serineprotease and metalloprotease, respectively, on the pathogenesis of Aeromonas ssp. has been demonstrated. Similar to a variety of virulent factors, the expression of metalloprotease and serineprotease genes is regulated by bacterial quorum sensing (QS) system. QS is a mechanism of cell-to-cell signaling that allow a bacterium to sense its own population. Anti QS potential of curcumin has been described in literature. Curcumin as a potent anti-QS agent, coult interrupt the proper expression of the protease genes and thus reduce bacterial virulence. We aimed to investigate the effect of curcumin on the expression of metalloprotease and serineprotease genes in A. hydrophila using qRT-PCR assay.Methods : The MIC (Minimum Inhibitory Concentration) of curcumin against A. hydrophila ATCC۷۹۶۶ was determined using the broth microdilution method and then, the bacterium was grown in Lauria broth medium containing a sub-MIC concentration of curcumin. After reaching the late exponential phase, the bacterial cells were harvested from the medium and subjected to RNA extraction and cDNA synthesis. The control cells were grown in the media lacking curcumin. Finally, the expression of the AHA_۳۸۵۷ and AHA_۰۹۸ genes was investigated by quantitative Polymerase Chain Reaction (qPCR) using gene-specific primers. In addition, the ۱۶s rRNA gene was used as an internal reference gene.Results : The MIC of curcumin was determined ۱۰۲۴ µg/mL and bacteria grown in the media containing curcumin with a concentration of ۵۱۲ µg/mL were selected for further experiments. Our results showed that the expression of AHA_۳۸۵۷ and AHA_۰۹۸ genes among curcumin-treated cells reduced by ۶۶ and ۷۷% , respectively, compared with the control cells.Conclusion : In this study, we showed that curcumin significantly reduced the expression of AHA_۳۸۵۷ and AHA_۰۹۸ genes. Attenuation of these genes by curcumin can reduce bacterial infectivity and pathogenicity. Thus, curcumin could be regarded as a promising anti-QS agent to be used against A. hydrophila infections.

کلیدواژه ها:

Aeromonas hydrophila ، curcumin ، Metalloprotease ، Serineprotease