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ORIGINAL RESEARCH article

Front. Immunol.
Sec. Comparative Immunology
Volume 15 - 2024 | doi: 10.3389/fimmu.2024.1527088

AIP56, an AB toxin secreted by Photobacterium damselae subsp. piscicida, has tropism for myeloid cells

Provisionally accepted
Inês Lua Freitas Inês Lua Freitas 1,2,3Fatima Macedo Fatima Macedo 4,5Liliana Oliveira Liliana Oliveira 4,5Pedro Oliveria Pedro Oliveria 6Ana do Vale Ana do Vale 2,3*Nuno M. S. dos Santos Nuno M. S. dos Santos 2,3*
  • 1 McBiology Doctoral Program, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal
  • 2 Fish Immunology and Vaccinology Group, IBMC – Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
  • 3 Fish Immunology and Vaccinology Group, i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
  • 4 Cell Activation and Gene Expression, IBMC – Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
  • 5 Cell Activation and Gene Expression, i3S – Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
  • 6 EPIUnit, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Porto, Portugal

The final, formatted version of the article will be published soon.

    The AB-type toxin AIP56 is a key virulence factor of Photobacterium damselae subsp. piscicida (Phdp), inducing apoptosis in fish immune cells. The discovery of AIP56-like and AIP56-related toxins in diverse organisms, including human-associated Vibrio strains, highlights the evolutionary conservation of this toxin family, suggesting that AIP56 and its homologs may share conserved receptors across species. These toxins have potential for biotechnological applications, such as therapeutic protein delivery and immune modulation. Herein, the cell specificity of AIP56 for immune cells in sea bass, mice, and humans was characterized. Whether AIP56 interacts directly or indirectly with sea bass neutrophils was never investigated. Here, it was shown that only a small population of sea bass neutrophils internalized AIP56, indicating that most of the neutrophilic destruction during Phdp infection and/or AIP56 intoxication does not result from the direct action of the toxin. Moreover, the cellular tropism of AIP56 for myeloid cells was observed in the three species, including its preference for macrophages. Further, mouse and human M0 and M2-like macrophages internalized more toxin than M1-like macrophages. Despite the limited interaction of lymphoid cells with AIP56, mouse B1-cells were able to internalize the toxin, possibly due to its myeloid features. These findings are relevant for both pathogenicity and biomedical contexts.

    Keywords: Photobacteriosis, virulence factor, toxins, Cellular tropism, Leukocytes, Macrophages, NF-B

    Received: 12 Nov 2024; Accepted: 17 Dec 2024.

    Copyright: © 2024 Freitas, Macedo, Oliveira, Oliveria, do Vale and dos Santos. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Ana do Vale, Fish Immunology and Vaccinology Group, IBMC – Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
    Nuno M. S. dos Santos, Fish Immunology and Vaccinology Group, IBMC – Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal

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