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Thymosin ?1 activates complement receptor-mediated phagocytosis in human monocyte-derived macrophages.

ABSTRACT: Thymosin ?1 (T?1) is a naturally occurring thymic peptide used worldwide in clinical trials for the treatment of infectious diseases and cancer. The immunomodulatory activity of T?1 on innate immunity effector cells has been extensively described, but its mechanism of action is not completely understood. We report that T?1-exposed human monocyte-derived macrophages (MDMs) assume the typical activated morphology also exhibited by lipopolysaccharide-activated MDMs, but show a comparatively higher ability of internalizing fluorescent beads and zymosan particles. T?1 exposure also promptly and dramatically stimulates MDM phagocytosis and killing of Aspergillus niger conidia starting as soon as 30 min after challenge. The effect is dose dependent and early coupled to low transcription of the proinflammatory cytokines tumor necrosis factor ? and interleukin-6 and unmodified Toll-like receptor expression. The T?1-stimulated phagocytosis is strictly dependent on the integrity of the microtubule network and protein kinase C activity and occurs by a variation in the classic zipper model, with recruitment of vinculin and actin at the phagosome exhibiting a punctate distribution. These findings indicate that, in human mature MDMs, T?1 implements pathogen internalization and killing via the stimulation of the complement receptor-mediated phagocytosis. Our observations document that T?1 is an early and potent activator of innate immunity and reinforce the concept of its pleiotropy.

SUBMITTER: Serafino A

PROVIDER: S-EPMC6741600 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Thymosin α1 activates complement receptor-mediated phagocytosis in human monocyte-derived macrophages.

Serafino Annalucia A Pica Francesca F Andreola Federica F Gaziano Roberta R Moroni Noemi N Moroni Gabriella G Zonfrillo Manuela M Pierimarchi Pasquale P Sinibaldi-Vallebona Paola P Garaci Enrico E

Journal of innate immunity 20130622 1

Thymosin α1 (Tα1) is a naturally occurring thymic peptide used worldwide in clinical trials for the treatment of infectious diseases and cancer. The immunomodulatory activity of Tα1 on innate immunity effector cells has been extensively described, but its mechanism of action is not completely understood. We report that Tα1-exposed human monocyte-derived macrophages (MDMs) assume the typical activated morphology also exhibited by lipopolysaccharide-activated MDMs, but show a comparatively higher ...[more]

PMID: 23797159

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Project description:Macrophages are an important line of defence against invading pathogens. Human macrophages derived by different methods were tested for their suitability as models to investigate Listeria monocytogenes (Lm) infection and compared to macrophage-like THP-1 cells. Human primary monocytes were isolated by either positive or negative immunomagnetic selection and differentiated in the presence of granulocyte macrophage colony-stimulating factor (GM-CSF) or macrophage colony-stimulating factor (M-CSF) into pro- or anti-inflammatory macrophages, respectively. Regardless of the isolation method, GM-CSF-derived macrophages (GM-Mφ) stained positive for CD206 and M-CSF-derived macrophages (M-Mφ) for CD163. THP-1 cells did not express CD206 or CD163 following incubation with PMA, M- or GM-CSF alone or in combination. Upon infection with Lm, all primary macrophages showed good survival at high multiplicities of infection whereas viability of THP-1 was severely reduced even at lower bacterial numbers. M-Mφ generally showed high phagocytosis of Lm. Strikingly, phagocytosis of Lm by GM-Mφ was markedly influenced by the method used for isolation of monocytes. GM-Mφ derived from negatively isolated monocytes showed low phagocytosis of Lm whereas GM-Mφ generated from positively selected monocytes displayed high phagocytosis of Lm. Moreover, incubation with CD14 antibody was sufficient to enhance phagocytosis of Lm by GM-Mφ generated from negatively isolated monocytes. By contrast, non-specific phagocytosis of latex beads by GM-Mφ was not influenced by treatment with CD14 antibody. Furthermore, phagocytosis of Lactococcus lactis, Escherichia coli, human cytomegalovirus and the protozoan parasite Leishmania major by GM-Mφ was not enhanced upon treatment with CD14 antibody indicating that this effect is specific for Lm. Based on these observations, we propose macrophages derived by ex vivo differentiation of negatively selected human primary monocytes as the most suitable model to study Lm infection of macrophages.

Dataset Information

Thymosin ?1 activates complement receptor-mediated phagocytosis in human monocyte-derived macrophages.

Publications

Thymosin α1 activates complement receptor-mediated phagocytosis in human monocyte-derived macrophages.

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