Circulating Helicobacter pylori extracellular vesicles in serum as biomarkers of infection

Gastric infection by Helicobacter pylori (H. pylori) is associated with extra-gastric pathologies. H. pylori can promote these pathologies by generating extracellular vesicles (Hp-EVs), which cross biological barriers and access other tissues through the circulation. However, the presence of Hp-EVs in the human circulation has not been demonstrated. We isolated and characterized EVs from serum of non-infected and infected patients, and used immunoblots (IB) to identify markers from host cells EVs (h-EVs) and Hp-EVs. We also assessed the predictive capacity of IB with an anti-Urease subunit B (UreB) antibody to identify true positive cases of H. pylori infection. Finally, we compared the diagnostic utility of IB-UreB with other detection methods of H. pylori in blood samples. Thirty symptomatic individuals underwent endoscopy, gastric biopsy and blood tests. Rapid Urease test (RUT), pathological analysis and Gastropanel® (GP) classified 16 cases (53.3%) as H. pylori positive. EV markers CD63 and CD81 were detected in all the isolated EVs from the serum of these patients. Moreover, UreB+ EVs were detected in 62.5% of H. pylori-infected patients, providing the first evidence of circulating Hp-EVs in human serum. Among the blood biomarkers evaluated, IB-UreB+ proved to be the best method for diagnosing H. pylori-positive cases. Furthermore, combining IB-UreB+ with GP increased its diagnostic value. Our findings provide the first evidence of circulating Hp-EVs in human serum, thereby supporting a mechanism for systemic dissemination of bacterial virulence factors. Additionally, their detection in blood samples may enable minimally invasive diagnosis of H. pylori infection.