1. Introduction
Helicobacter pylori (H. pylori) is an anaerobic gram-negative bacterium that causes many upper gastrointestinal infections [1]. The carcinogenic mechanism of H. pylori is not yet fully understood.  H. pylori induces inflammation in the mucosa and, eventually, gastric cancer through a cascading mechanism [2, 3, 4,  5]. 
One of the mechanisms of homeostasis in the body, the changes of which have recently been highly considered in various diseases, is autophagy. Autophagy occurs at basal levels and almost in all cells and tissues, but its extent can be changed in response to environmental conditions or excitatory and inhibitory signals [6]. One of the intermediate proteins in the autophagosome formation pathway is Autophagy-Related Gene 5 (ATG5). To date, no study has been conducted on serum changes in ATG5 associated with H. pylori infection and on the difference in these changes between the patient and healthy groups in the region. Therefore, this study aimed to investigate the mechanism of action of ATG5 in H. pylori infection.
2. Methods
This case-control pilot study was conducted in 2018 on 44 individuals aged 35-50 years referred to the endoscopy ward of Razi Hospital in Rasht, Iran. The sample size was estimated based on the study of Holly et al. [7]. The criteria for diagnosing H. pylori infection in the first stage were the results of Rapid Urease Test (RUT) (Zist Faravarde Pars Company) and pathology. Age, gender, Body Mass Index (BMI), smoking, and symptoms were recorded in a demographic form. Blood samples (5 cc) were taken from the participants and their serum was extracted by centrifuging (SIGMA, Germany) at 3500 rpm for 15 minutes. Serum samples were quantitatively measured for ATG5 by an ELISA kit (EIAab, USA). Data were analyzed in SPSS v.16 software, and the significance level was considered at P<0.05.
3. Results
In the present study, participants were 44 people (22 H. pylori-positive and 22 H. pylori-negative). Of these, 56.8% were male, 77.3% aged over 40 years, 70.5% had 1-12 years of education, 52.3% had BMI <25 kg/m2 and 70.5% were not smoking cigarette. Based on the results, the amount of ATG5 factor was statistically significant between women and men where that it was more in women (P= 0.047). No significant difference was observed in the presence of symptoms between people with and without H. pylori. There was no significant difference in the mean level of ATG5 between people with H. pylori (Mean=63.5±15.4) and without H. pylori (Mean=57.1±18.9) (P=0.228).
4. Conclusion
Serum concentration of ATG5 was significantly different between people with and without H. pylori infection only in terms of gender, where it was higher in women (66.2%) than in men (55.8%). No significant difference was observed in ATG5 level in terms of other demographic factors including age, education, BMI, and smoking. More studies are recommended on the relationship between these factors and serum ATG5 concentrations in patients with and without H. pylori infection using a larger sample size. It is also recommended to determine the relationship between endoscopic results and the presence of infection and between clinical indicators and autophagy. One of the limitations of this study was the lack of information about the duration of H. pylori infection in patients.

Ethical Considerations
Compliance with ethical guidelines
This study has an ethical approval obtained from the Ethics committee of Guilan University of Medical Sciences (Code: IR.GUMS.REC.1396.503). Ethical principles are fully observed in this article. Participants were allowed to leave the study whenever they wished. Also, all participants were aware of the research process. Their information was kept confidential.

Funding
This study was extracted from the thesis of the second author, and supported by the Deputy for Research and Technology of Guilan University of Medical Sciences.

Authors' contributions
Conceptualization: Fariborz Mansour-Ghanaei, Farahnaz Joukar; Methodology, software, validation, formal analysis, investigation, resources: All authors; Data curation, original draft preparation, review & editing: Fariborz Mansour-Ghanaei, Farahnaz Joukar, Alireza Mansour-Ghanaei, Sara Yeganeh; Administration: Fariborz Mansour-Ghanaei, Farahnaz Joukar, Iman Soufi Afshar.

Conflicts of interest
There are no conflicts of interest. 

Acknowledgements
The authors would like to thank the staff of the Gastrointestinal and Liver Diseases Research Center of Guilan University of Medical Sciences as well as the endoscopy department staff of Razi Hospital in Rasht for their cooperation.


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