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oai:figshare.com:article/34053150 2026-10-02T04:32:37Z category_696 portal_316 item_type_3 month_year_10_2026

Data Sheet 1_Targeting the capsule of Klebsiella pneumoniae with a cationic CR3-binding protein enhances phagocytosis and promotes bacterial clearance and survival in a mouse sepsis model.pdf Nataly P. Podolnikova (1654348) Iryna Klymenko (25161048) James Alagna (25161051) Cyrus Diercksmeier (25161054) Arnat Balabiyev (25161057) David Richardson (813629) Tatiana P. Ugarova (1654357) Genetic Immunology antibiotic resistance bacterial capsule CR3 Klebsiella pneumoniae Mac-1 PF4 phagocytosis <p>Platelet Factor 4 (PF4), a cationic antimicrobial peptide, serves as a ligand for the myeloid-specific phagocytic receptor CR3 (Mac-1, CD11b/CD18). We previously demonstrated that recombinant dimeric PF4 (rPF4) functions as a bacterial opsonin, enhancing phagocytosis of Gram-positive Staphylococcus aureus and facilitating clearance of both antibiotic-susceptible and methicillin-resistant S. aureus in a mouse model of infectious peritonitis. In this study, we examined whether rPF4 is pathogen-agnostic by assessing its effect on phagocytosis of Gram-negative encapsulated Klebsiella pneumoniae, a WHO Bacterial Priority Pathogen. We demonstrate that rPF4 enhances CR3-mediated phagocytosis of both live and heat-inactivated high-virulence K2 and low-virulence K3 strains of K. pneumoniae by various mouse and human macrophage cell lines, as well as primary neutrophils and macrophages. It also increased phagocytosis of carbapenem-resistant K. pneumoniae. rPF4 did not directly kill bacteria but acted as an opsonin, binding to the negatively charged bacterial capsule and creating recognition sites for CR3 on leukocytes. In a mouse sepsis model, a single dose of rPF4 significantly enhanced bacterial clearance from the lungs, liver, and peritoneum and reduced bacteremia. Histological analyses showed that rPF4 provided substantial protection to lung and liver tissues against K. pneumoniae-induced damage. Consistent with these findings, rPF4 treatment increased the survival rates of infected mice. These results show that rPF4 effectively targets the capsule, a key virulence factor of K. pneumoniae, thereby reducing the bacterium’s ability to evade the host immune response. Overall, the data suggest a common mechanism in which cationic rPF4, by binding to the negatively charged surfaces of both Gram-negative and Gram-positive bacteria, diminishes their antiphagocytic properties.</p> 2026-10-02T04:32:37Z Dataset Dataset 10.3389/fimmu.2026.1934439.s001 https://figshare.com/articles/dataset/Data_Sheet_1_Targeting_the_capsule_of_Klebsiella_pneumoniae_with_a_cationic_CR3-binding_protein_enhances_phagocytosis_and_promotes_bacterial_clearance_and_survival_in_a_mouse_sepsis_model_pdf/34053150 CC BY 4.0