Neutrophil mobilization is a crucial response to protect the host against invading microorganisms. Neutrophil recruitment and removal have to be tightly regulated to prevent uncontrolled inflammation and excessive release of their toxic content causing tissue damage and subsequent organ dysfunctions. We show here the presence of live and apoptotic neutrophils in the cytoplasm of inflamed mammary, urinary and gall bladder epithelial cells following infection with E. coli and Salmonella bacteria. The entry process commenced with adherence of transmigrated neutrophils to the apical membrane of inflamed epithelial cells. Next, nuclear rearrangement and elongation associated with extensive actin polymerization enabled neutrophils to crawl and invaginate the apical membrane into cytoplasmic double membrane compartments. Scission of the invaginated cell membrane from the entry point and loss of these surrounding membranes released intracellular neutrophils into the cytoplasm where they undergone apoptotic death. The co-occurrence of this observation with bacterial invasion and formation of intracellular bacterial communities (IBCs) might link entry of infected neutrophils to the formation of IBCs and chronic carriage in E. coli mastitis and cystitis and Salmonella cholecystitis.

中文翻译：

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乳腺，泌尿和胆囊感染中的上皮内嗜中性粒细胞。

中性粒细胞的动员是保护宿主免受入侵的微生物的关键反应。中性粒细胞的募集和清除必须严格控制，以防止不受控制的炎症和过量释放其毒性成分，从而引起组织损伤和随后的器官功能障碍。我们在这里显示感染大肠杆菌和沙门氏菌后，在炎症的乳腺，泌尿和胆囊上皮细胞的细胞质中存在活的和凋亡的中性粒细胞。进入过程开始于转移的嗜中性粒细胞粘附于发炎的上皮细胞的顶膜。接下来，与广泛的肌动蛋白聚合相关的核重排和延伸使嗜中性粒细胞爬行并侵入顶膜进入细胞质双膜区室。从入口处切开侵入的细胞膜并破坏这些周围的膜，将细胞内嗜中性粒细胞释放到细胞质中，并在其中发生凋亡性死亡。此观察与细菌入侵和细胞内细菌群落（IBCs）的共存可能将感染的中性粒细胞的进入与IBC的形成以及大肠杆菌乳腺炎，膀胱炎和沙门氏菌胆囊炎的慢性携带联系起来。