Helicobacter pylori Recombinant CagA Regulates Th1/Th2 Balance in a BALB/c Murine Model

Nafiseh Paydarnia,Mahyar Aghapour,Tohid Kazemi,Behzad Mansoori,Behzad Baradaran,Khalil Hajiasgharzadeh,Davoud Esmaeili,Nazila Alizadeh

doi:10.34172/apb.2020.031

Abstract

Purpose: Helicobacter pylori is recognized as one of the prevalent causes of human gastricinfection. In the present study, the role of mixed immunization with H. pylori lipopolysaccharide(LPS) and recombinant cytotoxin-associated gene A (rCagA) as a stimulator of host immuneresponses was determined. Methods: BALB/c mice were immunized with different formulations by the systemic administrationat 14-day intervals. The effects of the formulations plus CpG adjuvants were assessed before andpost-immunization in separated studies. Moreover, the expression of Th1/Th2 cytokines wasquantified in sera of immunized mice using reverse transcription polymerase chain reaction (RTPCR)test and the protein levels confirmed with enzyme linked immunosorbent assay (ELISA).Finally, the specific antibody levels in sera were studied by ELISA and the tendency of cellularresponse was examined by IgG1/IgG2a ratio. Results: Data of Western blotting verified the presence of constructed protein. Analysisof lymphocyte proliferation showed that CpG-conjugated rCagA increases lymphocytesproliferation compared to the control group. Also, it was shown that formulations containing LPSand rCagA promote a Th1 response indicated by interferon-gamma expression and induced Th1/Th2 balance. Additionally, the specific IgG1, total IgG and IgG2a levels elevated in response toall treatments. Ultimately, the IgG2a/IgG1 ratio in the mice immunized with rCagA-containingformulations increased. Conclusion: These results indicated that rCagA protein carried with CpG adjuvant not onlymaintained its antigenicity throughout the experiment but also induced robust Th1-biasedimmune responses. Therefore, it holds promise for the production of an efficient vaccine against H. pylori infection.

Highlights

Helicobacter pylori is known for its well-characterized implication in gastritis, a widespread complication with high incidence
CpG oligonucleotides contain unmethylated cytosine-guanosine dinucleotide motifs comparable to those observed in bacterial DNA that trigger Tolllike receptor 9 (TLR9) activation in the mammalian immune cells lead to T helper1 (Th1)-tilted response.[22]
In conclusion, we propose that immunization with appropriate H. pylori-extracted antigens and carrying them with an adjuvant can stimulate immune responses

Summary

Introduction

Helicobacter pylori is known for its well-characterized implication in gastritis, a widespread complication with high incidence. H. pylori infection may represent a latent feature in many individuals that remained unrecognized for years.[2] Mouse models have been extensively used to investigate the effectiveness and underlying mechanisms of vaccination. Though it is not identified that proper immunization routes can protect from H. pylori-induced diseases in individuals,[3] it may be proved for human use in the future.[4] Following H. pylori-induced infection, leukocytes and pro-inflammatory mediators recruit into the injured luminal surface. The strength of host inflammatory responses to H. pylori invasion is an indicative factor for mucosal damages, the less potent immunity the less protected gut epithelium.[5] Lipopolysaccharide (LPS) is ab important surface antigen that represents an essential function in the stability of the bacterial outer membrane. LPS of H. pylori is identified by less and longer fatty acid residues, lack of 4-phosphate

Methods

Results

Conclusion