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The Phagocytic Function of Macrophage-Enforcing Innate Immunity and Tissue Homeostasis

Daisuke Hirayama¹, Tomoya Iida², Hiroshi Nakase³

¹Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine, Minami 1-jo Nishi 16-chome, Chuo-ku, Sapporo, Hokkaido 060-8543, Japan. d.hirayama@sapmed.ac.jp.

International Journal of Molecular Sciences

|December 30, 2017

Abstract:

Macrophages are effector cells of the innate immune system that phagocytose bacteria and secrete both pro-inflammatory and antimicrobial mediators. In addition, macrophages play an important role in eliminating diseased and damaged cells through their programmed cell death. Generally, macrophages ingest and degrade dead cells, debris, tumor cells, and foreign materials. They promote homeostasis by responding to internal and external changes within the body, not only as phagocytes, but also through trophic, regulatory, and repair functions. Recent studies demonstrated that macrophages differentiate from hematopoietic stem cell-derived monocytes and embryonic yolk sac macrophages. The latter mainly give rise to tissue macrophages. Macrophages exist in all vertebrate tissues and have dual functions in host protection and tissue injury, which are maintained at a fine balance. Tissue macrophages have heterogeneous phenotypes in different tissue environments. In this review, we focused on the phagocytic function of macrophage-enforcing innate immunity and tissue homeostasis for a better understanding of the role of tissue macrophages in several pathological conditions.

Insights

Macrophages are key innate immune cells that engulf pathogens and cellular debris, maintaining tissue homeostasis. This review highlights their critical phagocytic role in host defense and tissue repair.

Area of Science:

Immunology
Cell Biology
Tissue Homeostasis

Background:

Macrophages are crucial effector cells of the innate immune system.
They phagocytose pathogens, clear cellular debris, and regulate inflammation.
Macrophages originate from monocytes and yolk sac progenitors, populating all vertebrate tissues.

Purpose of the Study:

To review the phagocytic functions of macrophages.
To elucidate their role in innate immunity and tissue homeostasis.
To understand the involvement of tissue macrophages in pathological conditions.

Main Methods:

Literature review focusing on macrophage phagocytosis.
Analysis of macrophage differentiation and tissue-specific phenotypes.
Examination of dual roles in host protection and tissue injury.

Main Results:

Macrophages exhibit diverse phenotypes and functions across different tissues.
Their phagocytic capacity is central to innate immunity and homeostasis.
A balance between host protection and tissue injury is maintained by macrophages.

Conclusions:

Macrophages are essential for innate immunity and maintaining tissue homeostasis through phagocytosis.
Understanding their diverse roles is critical for addressing various pathological conditions.
Further research into tissue-specific macrophage functions can reveal therapeutic targets.

Read full analysis

Keywords:

innate immunity macrophages phagocytosis

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