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Splenic Macrophage Subsets and Their Function during Blood-Borne Infections.

Borges da Silva H, Fonseca R, Pereira RM, Cassado Ados A, Álvarez JM, D'Império Lima MR - Front Immunol (2015)

Bottom Line: Marginal metallophilic macrophages (MMMΦs) and marginal zone macrophages (MZMΦs) are cells with great ability to internalize blood-borne pathogens such as virus or bacteria.Their localization adjacent to T- and B-cell-rich splenic areas favors the rapid contact between these macrophages and cells from adaptive immunity.Indeed, MMMΦs and MZMΦs are considered important bridges between innate and adaptive immunity.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Instituto de Ciências Biomédicas, Universidade de São Paulo , São Paulo , Brazil.

ABSTRACT
The spleen is one of the major immunological sites for maintaining blood homeostasis. Previous studies showed that heterogeneous splenic macrophage populations contribute in complimentary ways to control blood-borne infections and induce effective immune responses. Marginal metallophilic macrophages (MMMΦs) and marginal zone macrophages (MZMΦs) are cells with great ability to internalize blood-borne pathogens such as virus or bacteria. Their localization adjacent to T- and B-cell-rich splenic areas favors the rapid contact between these macrophages and cells from adaptive immunity. Indeed, MMMΦs and MZMΦs are considered important bridges between innate and adaptive immunity. Although red pulp macrophages (RpMΦs) are mainly considered scavengers for senescent erythrocytes, several data indicate a role for RpMΦs in control of infections such as blood-stage malaria as well as in the induction of innate and adaptive immunity. Here, we review current data on how different macrophage subsets recognize and help eliminate blood-borne pathogens, and, in turn, how the inflammatory microenvironment in different phases of infection (acute, chronic, and after pathogen clearance) influences macrophage function and survival.

No MeSH data available.


Related in: MedlinePlus

Localization and phenotype of splenic MΦ subsets. This figure is a broad scheme of the positioning of RpMΦs, MZMΦs, and MMMΦs inside spleen and their respective phenotypic markers. RpMΦs (in red) are typically found within cords on the red pulp, allowing direct contact with RBCs and other blood cells/particles passing through venous sinuses. They are better defined by the concomitant expression of F4/80, CD11b (at low levels), and CD68 as well as other receptors that aid in their function. MZMΦs (in green) are found in the marginal zone (MZ) outer layer – they are also in direct contact with blood-borne particles. These cells express in their surface the molecules MARCO and SIGNR1 and other receptors that help in the uptake of blood-borne pathogens. Finally, the MMMΦs (in brown) reside within the inner layer of the MZ, in the contact with the white pulp. They are also specialized in blood-borne particle uptake and express surface markers such as SIGLEC-1 and MOMA-1.
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Figure 1: Localization and phenotype of splenic MΦ subsets. This figure is a broad scheme of the positioning of RpMΦs, MZMΦs, and MMMΦs inside spleen and their respective phenotypic markers. RpMΦs (in red) are typically found within cords on the red pulp, allowing direct contact with RBCs and other blood cells/particles passing through venous sinuses. They are better defined by the concomitant expression of F4/80, CD11b (at low levels), and CD68 as well as other receptors that aid in their function. MZMΦs (in green) are found in the marginal zone (MZ) outer layer – they are also in direct contact with blood-borne particles. These cells express in their surface the molecules MARCO and SIGNR1 and other receptors that help in the uptake of blood-borne pathogens. Finally, the MMMΦs (in brown) reside within the inner layer of the MZ, in the contact with the white pulp. They are also specialized in blood-borne particle uptake and express surface markers such as SIGLEC-1 and MOMA-1.

Mentions: Effective control of infections through the immune system is ensured by the well-organized ­structure of secondary lymphoid organs, which allow capture, processing, and presentation of antigens, ultimately leading to successful elimination of pathogens and induction of adaptive immunity. Among lymphoid organs, the spleen is particularly shaped for clearance of blood-borne pathogens. Microanatomically, the spleen is divided into the white pulp and the red pulp (Rp), separated by the marginal zone (MZ) [reviewed in Ref. (1)]. Rp and MZ have a complex macrophage (MΦ) network with distinct origins and functions in the immune response to infections. RpMΦs form a vast network inside the Rp and are characterized in mice by expression of F4/80highCD68+CD11blow/− and intense autofluorescence (2). In turn, inside the MZ, two populations of MΦs can be discerned. The MZMΦs typically express in their surface the C-type lectin SIGN-related 1 (SIGNR1) and a type I scavenger receptor called Macrophage Receptor with Collagenous structure (MARCO), which recognize non-opsonized molecules (3), mainly blood-borne antigens (4). Furthermore, marginal metallophilic MΦs (MMMΦs) are defined, among other molecules, by the expression of Sialic acid-binding Ig-like Lectin-1 (Siglec-1, Sialoadhesin, CD169) and MOMA-1 (5). A general scheme of the spleen structure is depicted in Figure 1.


Splenic Macrophage Subsets and Their Function during Blood-Borne Infections.

Borges da Silva H, Fonseca R, Pereira RM, Cassado Ados A, Álvarez JM, D'Império Lima MR - Front Immunol (2015)

Localization and phenotype of splenic MΦ subsets. This figure is a broad scheme of the positioning of RpMΦs, MZMΦs, and MMMΦs inside spleen and their respective phenotypic markers. RpMΦs (in red) are typically found within cords on the red pulp, allowing direct contact with RBCs and other blood cells/particles passing through venous sinuses. They are better defined by the concomitant expression of F4/80, CD11b (at low levels), and CD68 as well as other receptors that aid in their function. MZMΦs (in green) are found in the marginal zone (MZ) outer layer – they are also in direct contact with blood-borne particles. These cells express in their surface the molecules MARCO and SIGNR1 and other receptors that help in the uptake of blood-borne pathogens. Finally, the MMMΦs (in brown) reside within the inner layer of the MZ, in the contact with the white pulp. They are also specialized in blood-borne particle uptake and express surface markers such as SIGLEC-1 and MOMA-1.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
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Figure 1: Localization and phenotype of splenic MΦ subsets. This figure is a broad scheme of the positioning of RpMΦs, MZMΦs, and MMMΦs inside spleen and their respective phenotypic markers. RpMΦs (in red) are typically found within cords on the red pulp, allowing direct contact with RBCs and other blood cells/particles passing through venous sinuses. They are better defined by the concomitant expression of F4/80, CD11b (at low levels), and CD68 as well as other receptors that aid in their function. MZMΦs (in green) are found in the marginal zone (MZ) outer layer – they are also in direct contact with blood-borne particles. These cells express in their surface the molecules MARCO and SIGNR1 and other receptors that help in the uptake of blood-borne pathogens. Finally, the MMMΦs (in brown) reside within the inner layer of the MZ, in the contact with the white pulp. They are also specialized in blood-borne particle uptake and express surface markers such as SIGLEC-1 and MOMA-1.
Mentions: Effective control of infections through the immune system is ensured by the well-organized ­structure of secondary lymphoid organs, which allow capture, processing, and presentation of antigens, ultimately leading to successful elimination of pathogens and induction of adaptive immunity. Among lymphoid organs, the spleen is particularly shaped for clearance of blood-borne pathogens. Microanatomically, the spleen is divided into the white pulp and the red pulp (Rp), separated by the marginal zone (MZ) [reviewed in Ref. (1)]. Rp and MZ have a complex macrophage (MΦ) network with distinct origins and functions in the immune response to infections. RpMΦs form a vast network inside the Rp and are characterized in mice by expression of F4/80highCD68+CD11blow/− and intense autofluorescence (2). In turn, inside the MZ, two populations of MΦs can be discerned. The MZMΦs typically express in their surface the C-type lectin SIGN-related 1 (SIGNR1) and a type I scavenger receptor called Macrophage Receptor with Collagenous structure (MARCO), which recognize non-opsonized molecules (3), mainly blood-borne antigens (4). Furthermore, marginal metallophilic MΦs (MMMΦs) are defined, among other molecules, by the expression of Sialic acid-binding Ig-like Lectin-1 (Siglec-1, Sialoadhesin, CD169) and MOMA-1 (5). A general scheme of the spleen structure is depicted in Figure 1.

Bottom Line: Marginal metallophilic macrophages (MMMΦs) and marginal zone macrophages (MZMΦs) are cells with great ability to internalize blood-borne pathogens such as virus or bacteria.Their localization adjacent to T- and B-cell-rich splenic areas favors the rapid contact between these macrophages and cells from adaptive immunity.Indeed, MMMΦs and MZMΦs are considered important bridges between innate and adaptive immunity.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunology, Instituto de Ciências Biomédicas, Universidade de São Paulo , São Paulo , Brazil.

ABSTRACT
The spleen is one of the major immunological sites for maintaining blood homeostasis. Previous studies showed that heterogeneous splenic macrophage populations contribute in complimentary ways to control blood-borne infections and induce effective immune responses. Marginal metallophilic macrophages (MMMΦs) and marginal zone macrophages (MZMΦs) are cells with great ability to internalize blood-borne pathogens such as virus or bacteria. Their localization adjacent to T- and B-cell-rich splenic areas favors the rapid contact between these macrophages and cells from adaptive immunity. Indeed, MMMΦs and MZMΦs are considered important bridges between innate and adaptive immunity. Although red pulp macrophages (RpMΦs) are mainly considered scavengers for senescent erythrocytes, several data indicate a role for RpMΦs in control of infections such as blood-stage malaria as well as in the induction of innate and adaptive immunity. Here, we review current data on how different macrophage subsets recognize and help eliminate blood-borne pathogens, and, in turn, how the inflammatory microenvironment in different phases of infection (acute, chronic, and after pathogen clearance) influences macrophage function and survival.

No MeSH data available.


Related in: MedlinePlus