Corresponding to Fig 4J.

Helicobacter pylori (H. pylori) is a bacterial pathogen that exclusively colonizes the human gastric mucosa and can cause persistent infection. In this process, H. pylori employs various strategies to avoid recognition by the human immune system. These range from passive defense strategies (e.g., altered LPS or flagellin structures) that prevent recognition by pattern recognition receptors (PRRs) to more active approaches, such as inhibition of IL-2 secretion and proliferation of T cells via VacA. Despite the growing evidence that H. pylori actively manipulates the human immune system for its own benefit, the direct interaction of H. pylori with immune cells in situ is poorly studied. Here, we present a novel intravital imaging model of the murine stomach gastric mucosa and show for the first time the in situ recruitment of neutrophils during infection and a direct H. pylori-macrophage interaction. For this purpose, we applied multiphoton intravital microscopy adapted with live drift correction software (VivoFollow) on LysM-eGFP and CX3CR1-eGFP reporter mice strains in which specific subsets of leukocytes are fluorescently labeled. Multiphoton microscopy is proving to be an excellent tool for characterizing interactions between immune cells and pathogens in vivo.

幽门螺杆菌（Helicobacter pylori，简称H. pylori）是一种特异性定植于人类胃黏膜的细菌性病原体，可引发持续性感染。在感染过程中，H. pylori演化出多种逃避免疫系统识别的策略：既包含被动防御手段，例如改变脂多糖（lipopolysaccharide, LPS）或鞭毛蛋白的结构以避免被模式识别受体（pattern recognition receptors, PRRs）识别；也涵盖主动调控策略，例如通过VacA抑制白细胞介素-2（interleukin-2, IL-2）的分泌以及T细胞的增殖。尽管越来越多的研究证据表明，H. pylori会主动调控人类免疫系统以谋求自身生存，但目前学界对H. pylori与原位免疫细胞的直接相互作用的研究仍较为匮乏。本研究构建了一种新型小鼠胃黏膜活体成像模型，并首次展示了感染过程中中性粒细胞的原位招募现象以及H. pylori与巨噬细胞的直接相互作用。为此，我们将搭载活体漂移校正软件（VivoFollow）的多光子活体显微镜技术，应用于LysM-eGFP与CX3CR1-eGFP报告基因小鼠品系——这类小鼠的特定白细胞亚群已被荧光标记。多光子显微镜已被证实是体内表征免疫细胞与病原体相互作用的优质工具。