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ABSTRACT
Purpose
Besides comprising scaffolding, extracellular matrix components modulate many biological processes including inflammation and cell differentiation. We previously found precoating cell plates with extracellular matrix collagen I, or its denatured product gelatin, causes aggregation of macrophage-like human lymphoma U937 cells, which are induced to differentiation by phorbol myristate treatment. In the present study, we investigated the influence of gelatin or collagen I precoating on the bacteria phagocytosis in PMA-stimulated U937 cells.
Materials and Methods
Colony forming units of phagocytosed bacteria, Giemsa-staining of cells with phagocytosed bacteria, confocal microscopic and flow cytometric analysis of cells with phagocytosed FITC-labeled bacteria and non-bioactive latex beats were conducted.
Results
Gelatin precoating enhances the phagocytosis of both Gram-negative and positive bacteria, as shown by the increased colony forming units of bacteria phagocytosed by cells, and increased intracellular bacteria observed after Giemsa-staining. But collagen I has no marked influence. Confocal microscopy reveals that both live and dead FITC-bacteria were phagocytosed more in the cells with gelatin-coating but not collagen-coating. Of note, both gelatin and collagen I coating had no influence on the phagocytosis of non-bioactive latex beads. Since gelatin-coating increases autophagy but collagen I has no such impact, we are curious about the role of autophagy. Inhibiting autophagy reduced the phagocytosis of bacteria, in cells with gelatin-coating, while stimulating autophagy enhanced phagocytosis.
Conclusion
This study finds the bacteria-phagocytosis stimulatory effect of gelatin in PMA-treated U937 cells and reveals the positive regulatory role of autophagy, predicting the potential use of gelatin products in anti-bacterial therapy.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Supplementary material
Supplemental data for this article can be accessed online at https://doi.org/10.1080/03008207.2024.2330693
Author contribution
Li Meiling: Writing-Original draft, Conceptualization, Methodology, Investigation, Formal analysis. Chen Yiran: Methodology, Investigation, Formal analysis. Sun Xiaoli: Investigation, Data curation, Formal analysis. Chen Kaihui: Formal analysis, Investigation. Hayashi Toshihiko: Writing-Review and Editing, Methodology. Itoh Kikuji: Resources, Writing-Review and Editing. Liu Weiwei: Project administration, Funding acquisition, Writing-Review and Editing. Hitomi Fujisaki, Kazunori Mizuno and Shunji Hattori: Resources, Writing-Review and Editing. Ikejima Takashi: Supervision, Project administration, Funding acquisition, Writing-Review and Editing.
Glossary
ECM: Extracellular matrix; collagen I: type I collagen; PMA: Phorbol 12-myristate 13-acetate; G−: Gram-negative bacteria; G+: Gram-positive bacteria; CFU: colony forming units; PGE2: prostaglandin E2; DMSO: di-methylsulfoxide; MDC: monodansylcadaverine; 3 MA: 3-methyladenine; PBS: phosphate buffered saline; E. coli: Escherichia coli; S. aureus: Staphylococcus aureus; P. aeruginosa: Pseudomonas aeruginosa; E. faecium: Enterococcus faecium; MRSA: Methicillin-resistant Staphylococcus aureus; LB: Luria-Bertani; BHI: Brain-Heart Infusion; TSB: Tryptic Soy Broth; FITC: fluorescein isocyanate; DAPI: 2-(4-Amidinophenyl)-6-indolecarbamidine dihydrochloride; LAP: LC3-associated protein;