Prior studies reported that non-gastric Helicobacter species, including Hh, H. typhlonius and H. apodemus, promoted the host tolerance via induction of regulatory T cells that restrained Hh-specific proinflammatory Th17 cells in immunocompetent C57BL/6J mice, but induced colitogenic Th17 cells during colitis in immunocompromised mice (Rag1−/− and Il10-deficient B6 mice) [24,25]. The gene discussed is RAG1; the disease is colitis.