Hilgarth, R. | Search bioRxiv

bioRxiv2026

The Protein Tyrosine Phosphatase CD45 promotes PMN Transepithelial Migration, Antimicrobial Function and Colonic Mucosal Repair

Polymorphonuclear neutrophils (PMNs) serve as frontline defenders against injury and infection, eliminating pathogens and initiating mucosal tissue repair. However, excessive PMN transepithelial migration (TEpM) contributes to chronic mucosal inflammatory disorders, including inflammatory bowel disease. PMN pro-inflammatory and pro-repair functions are regulated by incompletely defined signaling cascades involving kinases and phosphatases. Here, we determined how the protein tyrosine phosphatase CD45/PTPRC regulates PMN trafficking and effector functions in the gut. Pharmacologic inhibition of CD45 significantly reduced PMN colonic TEpM in vitro and in vivo and decreased intestinal PMN trafficking was observed in transgenic mice with PMN-specific deletion of CD45 (MRP8-Cre;Cd45fl/fl). Beyond limiting TEpM, CD45 depletion impaired key antimicrobial functions, including degranulation and phagocytosis, indicating broader effects on PMN effector activity. Importantly, recovery from dextran sodium sulfate (DSS)-induced colitis and biopsy-induced colonic wounding was delayed in MRP8-Cre;Cd45fl/fl mice, linking altered PMN function to defective mucosal healing. Mechanistically, CD45 depletion reduced surface expression of the {beta}2 integrin CD11b/CD18 and inactivated the Src family kinase member Lyn. Together, data highlight a novel CD45-CD11b-Lyn signaling axis that regulates PMN trafficking and effector functions in the intestine and identify CD45 as a promising target for modulating PMN function to promote mucosal tissue repair.

immunology↗

bioRxiv2025

Splicing of HPV16 E6 promotes aggressive invasion in oropharyngeal cancer via endocytosis of E-cadherin

Human papillomavirus-positive oropharyngeal squamous cell carcinoma (HPV+ OPSCC) has become the most common HPV-associated cancer in developed countries, yet a significant subset of patients develops recurrence despite favorable treatment responses. Biomarkers that identify aggressive tumors at diagnosis are therefore needed. In HPV+ cancers, the viral E6 transcript can be expressed as two main variants, the full-length isoform (E6FL) and the spliced E6*I isoform. Here, we investigated the functional and clinical impact of E6FL and E6*I in HPV+OPSCC. Across multiple preclinical models, E6*I promoted migration and aggressive invasion relative to E6FL and was associated with redistribution of E-cadherin away from the cell membrane. In multi-institutional patient cohorts, a previously developed E6FL:E6ALL influence score, which captures E6 splicing-associated host transcriptional biology, was associated with clinical outcomes. Lower scores, reflecting greater E6*I impact, were associated with worse overall survival and recurrence-free survival. Multiplexed immunofluorescence of 75 primary pretreatment biopsies further showed that a lower influence score was linked to reduced membrane and increased cytoplasmic localization of E-cadherin, while a tissue-based E-cadherin localization score was associated with recurrence. Mechanistically, E6*I overexpression promotes E-cadherin internalization, likely through the Rab11-associated trafficking pathway. Splice-switching oligonucleotides that shifted endogenous E6 splicing toward E6FL reduced invasion in two HPV+ OPSCC models. Together, these findings position HPV E6 splicing as a regulatory axis underlying aggressive HPV+ OPSCC biology and support E6 splicing and membrane-to-cytoplasmic ECAD localization as candidate risk-stratification biomarkers.

cancer biology↗