Washed microbiota transplantation is associated with Helicobacter pylori-negative conversion and circulating group 2...

Antibiotic resistance remains a major challenge in the management of Helicobacter pylori (H. pylori) infection. Microbiota-based interventions, including washed microbiota transplantation (WMT), have emerged as potential adjunctive strategies; however, their clinical outcomes in H. pylori infection and associated host immune alterations remain insufficiently characterized.

This retrospective observational study included two independent cohorts from January 2020 to January 2025. The WMT outcome cohort comprised patients with baseline H. pylori positivity who completed WMT and had available post-treatment reassessment. Patients receiving prior or concomitant standard H. pylori eradication therapy were excluded. Post-WMT H. pylori status was assessed, and safety outcomes were recorded. The peripheral blood immune profiling cohort included individuals with confirmed H. pylori status and available peripheral blood samples. Circulating innate lymphoid cell (ILC) subsets, including ILC2s and integrin α4⁺ ILC2s, were analyzed by flow cytometry, and their associations with clinical phenotypes and post-WMT H. pylori status were explored.

The WMT cohort included 42 patients [mean age, 56.60 ± 14.65 years; 30 men (71.43%)]. During a median follow-up of 196.5 days (IQR, 44.5-595.0 days), 23 patients achieved post-WMT H. pylori-negative conversion, corresponding to an observed conversion proportion of 54.76% (23/42; exact 95% CI, 38.67-70.15%). Ninety-six WMT procedures were performed, with adverse events occurring in 5 procedures involving 5 patients. In the immune profiling cohort, patients with H. pylori infection exhibited higher circulating ILC2 and integrin α4⁺ ILC2 proportions and lower ILC1 proportions than healthy controls. Circulating ILC2-related parameters were associated with selected infection-related clinical features, including anti-H. pylori antibody levels and virulence-factor status. In available post-WMT immune samples, lower circulating ILC2 proportions were observed compared with available baseline samples, and patients with subsequent H. pylori-negative conversion showed lower circulating ILC2 proportions than those with persistent positivity.

In this retrospective uncontrolled study, WMT exposure was associated with subsequent H. pylori-negative conversion and a low recorded adverse-event rate. Alterations in circulating ILC2-related profiles were associated with H. pylori infection status and post-WMT outcomes. These findings provide preliminary observational evidence supporting further investigation of WMT as an adjunctive microbiota-based strategy and of circulating ILC2-related parameters as potential immune biomarkers.