{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T19:21:10Z","timestamp":1792696870819,"version":"4.5.0"},"reference-count":46,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,2,23]],"date-time":"2026-02-23T00:00:00Z","timestamp":1771804800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>\n                      Probiotics such as\n                      <jats:italic>Lactobacillus rhamnosus<\/jats:italic>\n                      represent promising alternatives to antibiotics for combating enteric infections, yet their mechanisms of action remain incompletely understood. This study aimed to elucidate the protective mechanisms of\n                      <jats:italic>L. rhamnosus<\/jats:italic>\n                      CIQ249 against enteropathogenic bacterial infection, focusing on the intestinal physical barrier and mucosal immune responses.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      The intestinal colonization ability of CIQ249 was assessed using cFDA-SE labeling and flow cytometry. Growth performance and intestinal morphology were evaluated in mice. Antimicrobial activity of CIQ249 cell-free supernatant was tested against various pathogens, and pathogen damage was visualized by scanning electron microscopy. Protective effects against\n                      <jats:italic>Salmonella typhimurium<\/jats:italic>\n                      and\n                      <jats:italic>Escherichia coli<\/jats:italic>\n                      K99 were examined in a mouse model. Tight junction protein expression was analyzed\n                      <jats:italic>in vitro<\/jats:italic>\n                      and\n                      <jats:italic>in vivo<\/jats:italic>\n                      using immunofluorescence, qRT-PCR, and Western blot. Immune responses\u2014 including cytokine production, dendritic cell (DC) activation, T follicular helper (Tfh) cell differentiation, and IgA secretion\u2014were assessed by ELISA, flow cytometry, and immunohistochemistry. Transcriptomic changes in porcine intestinal epithelial cells (PIEC) were analyzed by RNA-seq.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      CIQ249 demonstrated strong intestinal colonization and increased villus height and the villus-to-crypt ratio, contributing to improved growth performance. Its cell-free supernatant selectively inhibited enteropathogens and induced structural damage in\n                      <jats:italic>S. typhimurium<\/jats:italic>\n                      and\n                      <jats:italic>E. coli<\/jats:italic>\n                      \u00a0K99. CIQ249 protected mice from lethal pathogen challenge, preserved intestinal architecture by upregulating tight junction proteins ZO-1 and Claudin-1. It also enhanced mucosal and systemic cytokine levels (IFN-\u03b3, IL-2, IL-4, IL-17, and IL-27), activated DCs, promoted differentiation of CXCR5+CD4+ Tfh and IgA-secreting plasma cells in Peyer\u2019s patches, leading to sIgA production. Transcriptome analysis revealed broad modulation of immune- and barrier-related pathways, with validation of key genes (e.g., IL-10, Masp2, Igf2).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>CIQ249 enhances mucosal defense against enteropathogenic bacteria through a dual mechanism\u2014strengthening the epithelial barrier and activating a coordinated DC\u2013Tfh\u2013IgA immune axis. These findings provide a multi-level mechanistic basis for its application as a microecological agent against intestinal infections.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fcimb.2026.1769889","type":"journal-article","created":{"date-parts":[[2026,2,23]],"date-time":"2026-02-23T06:30:53Z","timestamp":1771828253000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":4,"title":["Lactobacillus rhamnosus confers protection against enteropathogenic bacteria by enhancing mucosal immunity and epithelial barrier function"],"prefix":"10.3389","volume":"16","author":[{"given":"Xuwen","family":"Gao","sequence":"first","affiliation":[{"name":"College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering","place":["Guangzhou, China"]},{"name":"Shenzhen Key Laboratory of Pathogenic Microbes and Biosafety, School of Public Health (Shenzhen), Sun Yat-Sen University","place":["Shenzhen, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiangfei","family":"Zhou","sequence":"additional","affiliation":[{"name":"College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering","place":["Guangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kai","family":"Yan","sequence":"additional","affiliation":[{"name":"College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering","place":["Guangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yueming","family":"Guan","sequence":"additional","affiliation":[{"name":"College of Veterinary Medicine, Jilin Agricultural University","place":["Changchun, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jiayi","family":"Xiang","sequence":"additional","affiliation":[{"name":"College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering","place":["Guangzhou, China"]},{"name":"College of Veterinary Medicine, Zhejiang A&F University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yimei","family":"Liu","sequence":"additional","affiliation":[{"name":"College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering","place":["Guangzhou, China"]},{"name":"College of Veterinary Medicine, Zhejiang A&F University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Han","family":"Yu","sequence":"additional","affiliation":[{"name":"College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering","place":["Guangzhou, China"]},{"name":"College of Veterinary Medicine, Zhejiang A&F University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jing","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering","place":["Guangzhou, China"]},{"name":"College of Veterinary Medicine, Zhejiang A&F University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuan","family":"Li","sequence":"additional","affiliation":[{"name":"College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering","place":["Guangzhou, China"]},{"name":"College of Veterinary Medicine, Zhejiang A&F University","place":["Hangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yigang","family":"Xu","sequence":"additional","affiliation":[{"name":"College of Animal Science & Technology, Zhongkai University of Agriculture and Engineering","place":["Guangzhou, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,2,23]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"294","DOI":"10.1016\/j.cbi.2019.05.050","article-title":"Synergistic interactions of phytochemicals with antimicrobial agents: Potential strategy to counteract drug resistance","volume":"308","author":"Ayaz","year":"2019","journal-title":"Chem. 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