Defining the Helicobacter pylori Disease-Specific Antigenic Repertoire

Abstract

The analysis of the interaction between Helicobacter pylori (HP) and the host in vivo is an extremely informative way to enlighten the molecular mechanisms behind the persistency/latency of the bacterium as well as in the progression of the infection. An important source of information is represented by circulating antibodies targeting the bacteria that define a specific “disease signature” with prospective diagnostic implications. The diagnosis of some of the HP induced diseases such as gastric cancer (GC), MALT lymphoma (MALT), and autoimmune gastritis (AIG) is not easy because patients do not show symptoms of illness in early-onset stages, at the same time they progress rapidly. The possibility of identifying markers able to provide an early diagnosis would be extremely beneficial since a late diagnosis results in a delay in undergoing active therapy and reduces the survival rate of patients. With the aim to identify the HP antigens recognized during the host immune-response to the infection and possibly disease progression, we applied a discovery-driven approach, that combines “phage display” and deep sequencing. The procedure is based on the selection of ORF phage libraries, specifically generated from the pathogen’s genome, with sera antibodies from patients with different HP-related diseases. To this end two phage display libraries have been constructed starting from genomic DNA from the reference HP 26695 and the pathogenic HP B128 strains; libraries were filtered for ORFs by using an ORF selection vector developed by our group ( Di Niro et al., 2005 ; Soluri et al., 2018 ), selected with antibodies from patients affected by GC, MALT, and AIG and putative HP antigens/epitopes were identified after Sequencing and ranking. The results show that individual selection significantly reduced the library diversity and comparison of individual ranks for each condition allowed us to highlight a pattern of putative antigens specific for the different pathological outcomes or common for all of them. Within the putative antigens enriched after selection, we have validated protein CagY/Cag7 by ELISA assay as a marker of HP infection and progression. Overall, we have defined HP antigenic repertoire and identified a panel of putative specific antigens/epitopes for three different HP infection pathological outcomes that could be validated in the next future.

Synergistic Therapies as a Promising Option for the Treatment of Antibiotic-Resistant Helicobacter pylori

“…This microorganism is able to colonize and survive in stomach, which may lead to the development of physiological and morphological changes in this organ [ 2 , 3 ]. The appearance of gastric diseases is driven by the presence of a wide array of H. pylori virulence determinants, including toxins, enzymes, and adhesins [ 4 , 5 ]. All of them are responsible for countering the host’s defense mechanisms and establishing long-term colonization.…”

The Helicobacter pylori CagY Protein Drives Gastric Th1 and Th17 Inflammation and B Cell Proliferation in Gastric MALT Lymphoma

“…Helicobacter pylori CagY was produced as described [21]. We ruled out the presence of contaminants by a limulus test.…”

“…H. pylori strains harboring the cagPAI pathogenicity locus show a significantly increased ability to induce severe pathological outcomes in infected individuals, such as gastric cancer and gastric lymphoma, compared to cagPAI-negative strains [17][18][19][20]. Recently, it was reported that among H. pylori-infected patients, those with gastric low-grade MALT lymphoma are preferentially seropositive for H. pylori CagY protein [21]. CagY, a VirB10-homologous protein, also known as Cag7 or HP0527, is able to activate innate cells in a flagellin-independent manner.…”

Bacteriophages of Helicobacter pylori

“…CagPAI is a genetic locus of 40 kb, comprising 31 genes that encode a type IV secretion system (T4SS). The T4SS enables the injection of bacterial components, such as the CagA oncoprotein, into host gastric epithelial cells ( Soluri et al, 2020 ). VacA is a toxin secreted by H. pylori that inserts into host cell membranes to form chloride-sensitive channels and disrupt endolysosomal trafficking, causing an accumulation of dysfunctional lysosomes and autophagosomes ( Denic et al, 2020 ).…”