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Measuring Phagosome pH by Ratiometric Fluorescence Microscopy
Published on: December 7, 2015
Gallic acid promotes macrophage phagosome acidification and phagolysosome formation by activating NLRP3/mTOR
Yanqu Cai1, Jinzhu Jiang2, Chunhua Yue3
1Center for New Drug Research and Development, Guangdong Pharmaceutical University, No. 280, East Waihuan Road, Guangzhou Universities Town Campus, Guangzhou, China; Key Laboratory of Modern Chinese Medicine of Education Department of Guangdong Province, Guangdong Pharmaceutical University, No. 280, East Waihuan Road, Guangzhou Universities Town Campus, Guangzhou, China; Guangdong Provincial Key Laboratory of Advanced Drug Delivery Systems, Guangdong Pharmaceutical University, No. 280, East Waihuan Road, Guangzhou Universities Town Campus, Guangzhou, China; Class III Laboratory of Modern Chinese Medicine Preparation, State Administration of Traditional Chinese Medicine of the P.R.C, Guangdong Pharmaceutical University, No. 280, East Waihuan Road, Guangzhou Universities Town Campus, Guangzhou, China.
Introduction:
Gallic acid (GA) has a good therapeutic effect in bacteriological inhibition and plays a variety of functions in maintaining the stability of the immune system. The aim of the present study was to investigate the effect of GA on the bactericidal activity of macrophages against Vibrio vulnificus (Vv).
Methods:
A cell counting kit-8 (CCK-8) assay was carried out to test the cytotoxicity of GA on J774A.1 cells. Concentration of proinflammatory cytokines in J774A.1 cells were evaluated by ELISA. The internalization and degradation of Vv in the phagosomes were observed by transmission electron microscopy (TEM). The phagosome acidification and phagolysosome formation were detected to evaluate the bacteria-clearing function of J774A.1 cells. The bactericidal activity of GA in vivo was also investigated by collecting the survival time of Vv infected mice and observing the inflammatory infiltration of organs.
Results:
Our results demonstrated that GA at 50 μM significantly inhibited the proinflammatory cytokines levels, promoted phagosome acidification and phagolysosome formation in J774A.1 cells with Vv infection. This may be related to the activation of NLRP3/mTOR signaling pathway. Additionally, GA treatment improves the survival and bactericidal activity of mice infected with Vv.
Conclusions:
In summary, GA exerts bactericidal activity against Vv infection by regulating the formation and acidification of phagocytic lysosomes in macrophages.
