The co-evolved Helicobacter pylori and gastric cancer: trinity of bacterial virulence, host susceptibility and lifestyle

Abstract

Helicobacter pylori is an important yet unproven etiological agent of gastric cancer. H. pylori infection is more prevalent in developing Asian countries like India and it is usually acquired at an early age. It has been two decades since Marshall and Warren (1984) first described curved bacilli in the stomach of ulcer and gastritis patients. This discovery has won them the Nobel Prize recently, but the debate whether H. pylori is a pathogen or a commensal organism is still hot. Associations with disease-specific factors remain illusive years after the genome sequences were made available. Cytotoxin-associated antigen A (CagA) and the so-called plasticity region cluster genes are implicated in pathogenesis of the carcinoma of stomach. Another virulence factor VacA whose role is still debatable, has recently been projected in pathology of gastric cancer. Studies of the evolution through genetic variation in H. pylori populations have provided a window into the history of human population migrations and a possible co-evolution of this pathogen with its human host. Possible symbiotic relationships were seriously debated since the discovery of this pathogen. The debate has been further intensified as some studies proposed H. pylori infection to be beneficial in some humans. In this commentary, we attempt to briefly discuss about H. pylori as a human pathogen, and some of the important issues linked to its pathophysiology in different hosts.'We dance around in a ring and suppose, the secret sits in the middle and knows' – Robert Frost

Association of Helicobacter pylori vacA genotypes and peptic ulcer in Iranian population: a systematic review and meta-analysis

“…It seems that the infection by H. pylori can be related to socioeconomic status which in turn effects on papulation’s lifestyle. The outcomes of clinical manifestations of this bacterium are influenced by three factors, severity of strains, host genetics, and environment [ 56 ]. Reciprocally and over the time the stomach status such as acidity, buffering and mucus content can be affected by lifestyle factors such as diet, food habits, alcoholism, oral hygiene, water hygiene, personal hygiene, and so on [ 57 ].…”

Contaminated water as a source of Helicobacter pylori infection: A review

“…H. pylori , a bacterium initially observed in 1893 ( [14] cited in [15] ), has not been recognized as an infectious agent until 1982—in the seminal work of Nobel Laureates, Warren and Marshall [16–18] . H. pylori colonizes various regions of the upper digestive system, mainly the stomach and duodenum, causing stomach and duodenal ulcers and certain stomach cancers [9,19,20] . The infection is surprisingly common, and the bacteria are believed to colonize more than half of the world’s population [21] .…”

Recent Trends in System-Scale Integrative Approaches for Discovering Protective Antigens Against Mycobacterial Pathogens

“…Thus, it was concluded that targeting these potentially virulent factors would stop the disease establishment and would enable a rapid development of novel vaccines, antibiotics and new screening tests. The three main approaches that have been used for the identification of virulence genes from the complete genome involves: homology search with the experimentally characterized virulent factors ( Rana et al, 2015c ), identifying genes located in different pathogenic genomic islands ( Akhter et al, 2007 , 2008 , 2012 ; Che et al, 2014 ) and the third approach involves identification of the virulence genes by genome comparison of strains having different pathogenicity profiles (virulent versus avirulent strains). Using an in silico approach, a set of 189 putative vaccine candidates have been identified from the complete Mtb genome (3989 gene products) ( Zvi et al, 2008 ).…”