{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T21:33:06Z","timestamp":1788816786265,"version":"build-2803163510"},"reference-count":49,"publisher":"MDPI AG","issue":"13","license":[{"start":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T00:00:00Z","timestamp":1783382400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006606","name":"Natural Science Foundation of Tianjin","doi-asserted-by":"crossref","award":["24JCYBJC00440"],"award-info":[{"award-number":["24JCYBJC00440"]}],"id":[{"id":"10.13039\/501100006606","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Background: Tuber indicum is a rare edible and medicinal ectomycorrhizal fungus, and the polysaccharide fractions have attracted extensive research attention owing to their potent immunomodulatory potential. Objective\/Methods: To systematically characterize the structural features and gut microbiota-mediated immunoregulatory mechanisms of water-extracted polysaccharide (TIWP) and alkali-extracted polysaccharide (TIAP) from T. indicum, two polysaccharide fractions were prepared and comprehensively structurally characterized in this study. Results: The maximum molecular weight of TIWP reached 2.65 \u00d7 107 Da, which was dominated by glycosidic linkages of \u21923)-Glcp-(1\u2192, \u21922,4)-Glcp-(1\u2192 and \u21923,6)-Glcp-(1\u2192. TIAP possessed a higher molecular weight up to 3.87 \u00d7 107 Da, with predominant glycosidic bonds of \u21923,6)-Glcp-(1\u2192, \u21924)-Glcp-(1\u2192 and \u21922,4)-Glcp-(1\u2192. In vivo bioactivity evaluation results demonstrated that both TIWP and TIAP significantly restored the proportions of CD3+ T and CD19+ B lymphocyte subsets in peripheral blood and spleen, and alleviated pathological damage in splenic and colonic tissues. Distinct regulatory patterns of gut microbiota were observed between the two polysaccharides: TIWP markedly enriched the genera Lactobacillus and Ruminiclostridium, whereas TIAP elevated the relative abundances of Lactobacillus and Alloprevotella. Untargeted metabolomics combined with KEGG pathway enrichment analysis revealed that TIWP and TIAP activated the pantothenic acid and coenzyme A biosynthesis pathway and the linoleic acid metabolism pathway. Conclusions: Collectively, TIWP and TIAP alleviated CTX-triggered immunosuppression through distinct \u201cgut microbiota-metabolite-immunity\u201d regulatory networks due to their structural disparities. This study provides a theoretical basis for the development of gut microecology-targeted functional foods with immunomodulatory functions.<\/jats:p>","DOI":"10.3390\/nu18132202","type":"journal-article","created":{"date-parts":[[2026,7,7]],"date-time":"2026-07-07T09:53:46Z","timestamp":1783418026000},"page":"2202","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Structural Characteristics and Gut Microbiota-Mediated Immunomodulatory Mechanisms of Water- and Alkali-Extracted Polysaccharides from Tuber indicum"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-1996-4865","authenticated-orcid":false,"given":"Hongfei","family":"Ji","sequence":"first","affiliation":[{"name":"School of Life Sciences, Yantai University, Yantai 264005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6702-6286","authenticated-orcid":false,"given":"Mei","family":"Li","sequence":"additional","affiliation":[{"name":"School of Life Sciences, Yantai University, Yantai 264005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Decheng","family":"Mao","sequence":"additional","affiliation":[{"name":"School of Life Sciences, Yantai University, Yantai 264005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yujie","family":"Chen","sequence":"additional","affiliation":[{"name":"School of Life Sciences, Yantai University, Yantai 264005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bing","family":"Han","sequence":"additional","affiliation":[{"name":"School of Life Sciences, Yantai University, Yantai 264005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanli","family":"Zheng","sequence":"additional","affiliation":[{"name":"Institute of Agricultural Products Preservation and Processing Technology (National Engineering Technology Research Center for Preservation of Agriculture Product), Tianjin Academy of Agricultural Sciences, Tianjin 300384, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wenjie","family":"Ding","sequence":"additional","affiliation":[{"name":"College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0568-4048","authenticated-orcid":false,"given":"Haiyu","family":"Ji","sequence":"additional","affiliation":[{"name":"School of Life Sciences, Yantai University, Yantai 264005, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"101171","DOI":"10.1016\/j.cofs.2024.101171","article-title":"Food profiling: Progress in ensuring the authenticity of truffle species and their geographical origin","volume":"57","author":"Creydt","year":"2024","journal-title":"Curr. 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