Helicobacter pylori inflammation; Th1 or Th2

Background and aims: Chronic infections accompanied with gastric bacterial pathogens Helicobacter Pylori (H.pylori), are one of the major challenges of contemporary medicine era. Basically, control of these diseases need to a more vigorous response than active immunization. Various clinical protests are mainly development of gastric mucosal associated lymphoid tissue. So, the aim of this study is deciphering triggered immunological pathways linking inflammation and cancer. Search method: This systematic review was conducted to outline comprehensive studies published in PubMed, Scopus, Science Direct databases and Google Scholar search engine from 2003 up to August 2017 by using 6 keywords. 226 articles were screened and 143 were totally included. Results: Pro and anti-inflammatory responses by H.pylori are involved in shortterm acute inflammation (Th1) and tumor development topics (Th2), which are complicated by redundancy and pleiotropic functions of cytokines. The sequel pro or anti-inflammatory responses nominate switch variations and outcome of infection (persistence, elimination or adverse pathological reactions). H. pylori infection, first, induces local short-term acute inflammation, by provoking TNF-a, IL-1, 6; mediating host defense against infections. Amazing ability for co-existence and prolonged interaction between bacterium byproducts and host immune system, makes it a feasible infectious agent for Th1-mediated autoimmune disease stimulation and autoantibodies development. There are strong documentations on immunomodulation by H.pylori infection and development of many extra gastric chronic diseases such as: Urticaria, Psoriasis, Vasculitis, Schoenline Henoch Purpura, Typhoid fever, Chronic Hepatitis C, Thyroiditis Hashimoto and Graves Diseases. Then, in turn, chronic inflammation predispose the host to stomach cancer and it s progression or onset. In addition, H.pylori chronic infection may also be beneficial for conferring protection against allergy, Rhinitis, Asthma, Atopic Dermatitis and Inflammatory Bowel Diseases which are highly associated with suppressive Tregs function. Therefore, it should be noticed that there is a complex strong immune response to H.pylori infection, at both innate effectors and adaptive Th1, Th17 and Tregs levels. Development of colonic Treg cells limit local inflammation in the normal gut. Conclusion: The knowledge of the immune response to H. pylori is still incomplete.Totally, this study refers to a more detailed insight to the relationships between inflammation and cancer, and complicated functions of malignant/host cells-derived cytokines may be a promising window for inaccurate diagnosis overcoming, elimination of undesirable immunological reactions and interventions in cytokine expression at field of gastric cancer immunotherapy.

Keywords:

Helicobacter pylori , Chronic inflammation , Acute inflammation , Immunopathophisiology , Immunomodulation , Stomach immunology