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

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.

Targeting CD47 as a Novel Immunotherapy for Multiple Myeloma

“…Macrophages are part of the innate immune system, and they represent the first line of defense and respond quickly to threats such as tissue damage or infection [14]. Specifically, macrophages are the "professional eaters" of the immune system specialized in the detection, phagocytosis, and destruction of foreign substances, microbes, cancer cells, and other harmful organisms [15]. In addition, macrophages also function as antigen presenting cells, which induce and direct adaptive immune response (such as in T cells and B cells) [16].…”

Structural Basis and Designing of Peptide Vaccine using PE-PGRS Family Protein of Mycobacterium ulcerans – An Integrated Vaccinomics Approach

“…The control of Buruli ulcer is largely depends on the cellular immunity involving activated macrophages and Th1 type immune response through cytokine production (Gooding et al 2001;Huygen et al 2009;Prévot et al 2004;Yeboah-Manu et al 2006). Computer simulation of immune response triggered by our vaccine protein showed increased macrophage activity and longer-lasting Th1-mediated immune reactions that are essential for M. ulcerans clearance (Hirayama, Iida, and Nakase 2018). The active helper T-cell population was increasingly higher in secondary and tertiary responses compared to the primary response.…”

Anti-Inflammatory and Anti-Oxidative Activity of Indole-3-Acetic Acid Involves Induction of HO-1 and Neutralization of Free Radicals in RAW264.7 Cells

“…Long-term unhealthy diet-induced alteration of intestinal flora may contribute to metabolic endotoxemia characterized by the increase of lipopolysaccharide (LPS) in blood concentration [2]. As the first line of defense in the body against infectious pathogens, macrophages play crucial roles in the progression of tissue inflammation in response to LPS [3]. LPS activates macrophages to secrete proinflammatory cytokines (e.g., tumor necrosis factor-a (TNF-α), interleukin (IL)-1, and IL-6) and free radicals (e.g., reactive oxidative species (ROS) and nitric oxide (NO)) [4,5].…”