{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,6]],"date-time":"2026-06-06T05:00:59Z","timestamp":1780722059994,"version":"3.54.1"},"reference-count":86,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T00:00:00Z","timestamp":1780444800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cells"],"abstract":"<jats:p>Alzheimer\u2019s disease is characterized by a chronic, long-term neurodegenerative process and an increasing need for easily accessible biomarkers that enable early diagnosis and disease monitoring. For this reason, tears have attracted growing interest as a potential source of such biomarkers, and prolactin-inducible protein is a candidate tear protein of mechanistic interest whose clinical value remains to be established as a biomarker of Alzheimer\u2019s disease. The literature indicates that prolactin-inducible protein is physiologically present in the lacrimal apparatus. Proteomic studies in patients with Alzheimer\u2019s disease have repeatedly demonstrated decreased levels of prolactin-inducible protein in tears, typically accompanied by reduced concentrations of other proteins associated with normal lacrimal gland function. Although the evidence remains inconclusive, these findings suggest that alterations in prolactin-inducible protein levels may reflect lacrimal gland dysfunction related to neurodegenerative processes, autonomic dysregulation, and inflammation. Nevertheless, the lack of specificity of prolactin-inducible protein for Alzheimer\u2019s disease, as well as the influence of various factors on its concentration, limit its value as a standalone biomarker. The most plausible approach is the incorporation of prolactin-inducible protein into multimarker panels, which could enable improved patient stratification and assessment of lacrimal gland dysfunction in Alzheimer\u2019s disease.<\/jats:p>","DOI":"10.3390\/cells15111029","type":"journal-article","created":{"date-parts":[[2026,6,3]],"date-time":"2026-06-03T13:46:48Z","timestamp":1780494408000},"page":"1029","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Emerging Function of Prolactin-Inducible Protein\u2014Is This Important Tear Protein Found in Alzheimer\u2019s Disease?"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0005-5320-3658","authenticated-orcid":false,"given":"James","family":"Chmiel","sequence":"first","affiliation":[{"name":"Faculty of Physical Culture and Health, Institute of Physical Culture Sciences, University of Szczecin, Al. Piast\u00f3w 40B block 6, 71-065 Szczecin, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-0394-7835","authenticated-orcid":false,"given":"Wiktor","family":"Gawe\u0142czyk","sequence":"additional","affiliation":[{"name":"Student Scientific Group of Psychiatry, Wroclaw Medical University, Wybrze\u017ce L. Pasteura 10, 50-367 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3809-5028","authenticated-orcid":false,"given":"Julia","family":"Soczy\u0144ska","sequence":"additional","affiliation":[{"name":"Student Scientific Group of Psychiatry, Wroclaw Medical University, Wybrze\u017ce L. Pasteura 10, 50-367 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jerzy","family":"Leszek","sequence":"additional","affiliation":[{"name":"Department of Psychiatry, Wroclaw Medical University, 50-367 Wroclaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"100063","DOI":"10.1016\/j.bionps.2023.100063","article-title":"Biomarkers of Alzheimer\u2019s Disease: Past, Present and Future Clinical Use","volume":"8","author":"Georgakas","year":"2023","journal-title":"Biomark. Neuropsychiatry"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1002\/prca.201400084","article-title":"Unraveling the Molecular Repertoire of Tears as a Source of Biomarkers: Beyond Ocular Diseases","volume":"9","author":"Pieragostino","year":"2015","journal-title":"Proteom. Clin. 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