In vitro suppression of dendritic cells by Helicobacter pylori OipA.
BACKGROUND
Outer inflammatory protein A (OipA) has an important role in Helicobacter pylori pathogenesis. In this study, we purified the outer membrane protein and evaluated the effects of this protein on maturation and cytokine production by dendritic cells (DCs).


METHODS
The oipA gene was inserted into pET28a, and this construct was transformed into Escherichia coli BL21 (DE3). Purification of the recombinant protein was performed by Ni-NTA affinity chromatography. Immature DCs were purified from spleen of C57BL/6 mice with more than 90% purity and were treated with several concentrations of OipA (1-20 μg/mL) overnight. Expression of maturation markers (CD86, CD40, and MHC-II) on the surface of DCs and production of IL-10 and IL-12 were assessed by flow cytometry and ELISA, respectively.


RESULTS
The expression of DC maturation markers CD40, CD86, and MHC-II was downregulated on the surface of OipA-treated DCs at concentrations of 10 and 20 μg/mL compared with negative control. Production of IL-10 decreases with increasing OipA concentration at a concentration of 5 μg/mL, but we detected no change in IL-12 production.


CONCLUSIONS
Inability to eliminate H. pylori from stomach is partly due to the evasion of the bacteria from the immune response. DCs are central mediators between innate and adaptive immunity, and DC cytokines direct the types of adaptive immune response. This study indicated that OipA of H. pylori is a DC maturation suppression factor. Previous studies have shown that H. pylori manage tolerogenic programming in DCs leading to long-time gastric colonization. In conclusion, H. pylori OipA helps the establishment of chronic infection with reduction in IL-10 and suppression of DC maturation.
Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Omid
O
Teymournejad
Ashraf M
AM
Mobarez
Zuhair M
ZM
Hassan
Seyed M
SM
Moazzeni
Hassan N
HN
Ahmadabad
D000818:Animals; D051940:B7-2 Antigen / Q000096:biosynthesis; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000276:immunology*; D019013:CD40 Antigens / Q000096:biosynthesis; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology*; D015536:Down-Regulation; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D016481:Helicobacter Infections / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D016480:Helicobacter pylori / Q000276:immunology* / Q000472:pathogenicity; D000949:Histocompatibility Antigens Class II / Q000096:biosynthesis; D057131:Immune Evasion / Q000276:immunology*; D016753:Interleukin-10 / Q000096:biosynthesis; D018664:Interleukin-12 / Q000096:biosynthesis; D051379:Mice; D008810:Mice, Inbred C57BL; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*
D051940:B7-2 Antigen; D001425:Bacterial Outer Membrane Proteins; D019013:CD40 Antigens; C497965:Cd86 protein, mouse; D000949:Histocompatibility Antigens Class II; C556062:IL10 protein, mouse; C526444:OipA protein, Helicobacter pylori; D011994:Recombinant Proteins; D016753:Interleukin-10; D018664:Interleukin-12
Dendritic cell; Helicobacter pylori; OipA; suppression