The Helicobacter pylori protein HspB interferes with Nrf2/Keap1 pathway altering the antioxidant response of Ags cells.
BACKGROUND
Helicobacter pylori infection causes chronic oxidative stress on gastric mucosa, thereby causing mucosal damage and increasing the risk of gastric adenocarcinoma. Nrf2 is an important transcription factor, regulating the antioxidant response in the cells. Nrf2 signaling is repressed by Keap1 at basal condition and induced by oxidative stress. The aim of our study was to analyze whether the H. pylori proteins interfered in the Nrf2/Keap1 pathway.


METHODS
Gene expression in AGS cells transiently and stably transfected was analyzed by real-time PCR. Immunoprecipitation and immunofluorescence assays were performed to investigate the ability of H. pylori proteins to interfere with the Nrf2 pathway.


RESULTS
We demonstrated that the H. pylori HspB protein interferes with Nrf2/Keap1 pathway. When HspB was transiently transfected in AGS cells, a significant increase in Keap1 gene expression was induced. The same result was observed when AGS cells were HspB stably transfected. In this case, the increase in Keap1 was associated with reduced gene expression of Nrf2, and of the antioxidant enzymes superoxide dismutase, hemeoxygenase-1, and phase II detoxifying enzyme NAD(P)H:quinone oxidoreductase-1. Immunoprecipitation and immunofluorescence assays confirmed the ability of HspB protein to interfere with the Nrf2 pathway. Lastly, in HspB-transfected AGS cells, sustained activation of IL-8, COX2, MMP3, and MMP7 was demonstrated.


CONCLUSIONS
The results here reported suggest that inhibited nuclear translocation of Nrf2, associated with induced inflammation and increased production of MMPs, might represent a condition enhancing the risk of gastric adenocarcinoma.
Department of Experimental Medicine, Section of Microbiology and Clinical Microbiology, Second University of Naples, Naples, Italy.
Elisabetta
E
Buommino
Giovanna
G
Donnarumma
Lucrezia
L
Manente
Anna
A
De Filippis
Francesco
F
Silvestri
Salvatore
S
Iaquinto
Maria Antonietta
MA
Tufano
Antonio
A
De Luca
D000975:Antioxidants / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D002460:Cell Line; D004847:Epithelial Cells / Q000382:microbiology; D020869:Gene Expression Profiling; D006360:Heat-Shock Proteins / Q000378:metabolism*; D016480:Helicobacter pylori / Q000472:pathogenicity*; D006801:Humans; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2 / Q000037:antagonists & inhibitors*; D011485:Protein Binding; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D037521:Virulence Factors / Q000378:metabolism*
D000975:Antioxidants; D001426:Bacterial Proteins; D006360:Heat-Shock Proteins; C112564:HspB protein, Helicobacter pylori; D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D037521:Virulence Factors