Porcine Macrophage Markers and Populations: An Update.

Besides its importance as a livestock species, pig is increasingly being used as an animal model for biomedical research. Macrophages play critical roles in immunity to pathogens, tissue development, homeostasis and tissue repair. These cells are also primary targets for replication of viruses such as African swine fever virus, classical swine fever virus, and porcine respiratory and reproductive syndrome virus, which can cause huge economic losses to the pig industry.

Pharmacological Elevation of Cellular Dihydrosphingomyelin Provides a Novel Antiviral Strategy against West Nile Virus Infection.

The flavivirus life cycle is strictly dependent on cellular lipid metabolism. Polyphenols like gallic acid and its derivatives are promising lead compounds for new therapeutic agents as they can exert multiple pharmacological activities, including the alteration of lipid metabolism. The evaluation of our collection of polyphenols against West Nile virus (WNV), a representative medically relevant flavivirus, led to the identification of ,'-(dodecane-1,12-diyl)bis(3,4,5-trihydroxybenzamide) and its 2,3,4-trihydroxybenzamide regioisomer as selective antivirals with low cytotoxicity and high antiviral activity (half-maximal effective concentrations [ECs] of 2.

CD9 expression in porcine blood CD4 T cells delineates two subsets with phenotypic characteristics of central and effector memory cells.

In this report, we describe the characterization of a new monoclonal antibody, named 4H5CR4, against porcine CD9. Its use in combination with antibodies to CD4, CD8α, and 2E3 allows to distinguish at least five main CD4 T cell subsets. Analysis on these subsets of CD45RA, CD27, CD29, CD95, CCR7, and SLA-DR markers depicts a progressive model of CD4 T cell development.

CD200R family receptors are expressed on porcine monocytes and modulate the production of IL-8 and TNF-α triggered by TLR4 or TLR7 in these cells.

The inhibitory receptor CD200R1 and its paired activating receptor CD200R1L are involved in the regulation of myeloid cell immune responses. The aim of this study was to analyze their distribution, regulation by cytokines, and function in porcine monocyte subsets. We had previously observed that CD200R1 and CD200R1L genes can generate different protein isoforms through alternative mRNA splicing, therefore in this study, we explored the diversity of transcripts in monocyte subsets, and described several new splicing variants of both CD200R1 and CD200R1L, some of which could be expressed on the porcine monocyte surface.

The combined vaccination protocol of DNA/MVA expressing Zika virus structural proteins as efficient inducer of T and B cell immune responses.

Zika virus (ZIKV) is a mosquito-borne pathogen with public health importance due to the high risk of its mosquito vector dissemination and the severe neurological and teratogenic sequelae associated with infection. Vaccines with broad immune specificity and control against this re-emerging virus are needed. Here, we described that mice immunized with a priming dose of a DNA plasmid mammalian expression vector encoding ZIKV prM-E antigens (DNA-ZIKV) followed by a booster dose of a modified vaccinia virus Ankara (MVA) vector expressing the same prM-E ZIKV antigens (MVA-ZIKV) induced broad, polyfunctional and long-lasting ZIKV-specific CD4 and CD8 T-cell immune responses, with high levels of CD4 T follicular helper cells, together with the induction of neutralizing antibodies.

CD200R1 and CD200R1L expression is regulated during B cell development in swine and modulates the Ig production in response to the TLR7 ligand imiquimoid.

The CD200R family comprises a group of paired receptors that can modulate the activation of immune cells. They are expressed both on myeloid cells and lymphocyte subsets. Here we report that the expression of these receptors on porcine B cells is tightly regulated, being mainly expressed on mature cells.

Pathogenicity and virulence of West Nile virus revisited eight decades after its first isolation.

West Nile virus (WNV) is a flavivirus which transmission cycle is maintained between mosquitoes and birds, although it occasionally causes sporadic outbreaks in horses and humans that can result in serious diseases and even death. Since its first isolation in Africa in 1937, WNV had been considered a neglected pathogen until its recent spread throughout Europe and the colonization of America, regions where it continues to cause outbreaks with severe neurological consequences in humans and horses. Although our knowledge about the characteristics and consequences of the virus has increased enormously lately, many questions remain to be resolved.

Relevance of oxidative stress in inhibition of eIF2 alpha phosphorylation and stress granules formation during Usutu virus infection.

Usutu virus (USUV) is an African mosquito-borne flavivirus closely related to West Nile, Japanese encephalitis, Zika, and dengue viruses. USUV emerged in 1996 in Europe, where quickly spread across the continent causing a considerable number of bird deaths and varied neurological disorders in humans, including encephalitis, meningoencephalitis, or facial paralysis, thus warning about USUV as a potential health threat. USUV replication takes place on the endoplasmic reticulum (ER) of infected cells, inducing ER stress and resulting in the activation of stress-related cellular pathways collectively known as the integrated stress response (ISR).

Porcine CLEC12B is expressed on alveolar macrophages and blood dendritic cells.

CLEC12B is a C-type lectin-like receptor expressed on myeloid cells. In this study, we have characterized the porcine homologue of CLEC12B (poCLEC12B). To this end, we have generated constructs encoding a c-myc tagged version of the whole receptor, or its ectodomain fused to the Fc portion of human IgG1, from a cDNA clone obtained from an alveolar macrophage library, and raised monoclonal antibodies (mAb) against this molecule.

Characterization of the Porcine CLEC12A and Analysis of Its Expression on Blood Dendritic Cell Subsets.

CLEC12A has been proposed as a suitable target for delivering antigen to dendritic cells (DCs) to enhance vaccine efficacy both in human and mouse. In this study, we have characterized the porcine homolog of CLEC12A (poCLEC12A). Using new monoclonal antibodies (mAb), raised against its ectodomain, poCLEC12A was found to be expressed on alveolar macrophages, blood conventional type 1 and type 2 DCs and plasmacytoid DCs, but not on monocytes, T cells, B cells or NK cells, in contrast to its human and murine homologs.

Phenotypic and functional heterogeneity of CD169⁺ and CD163⁺ macrophages from porcine lymph nodes and spleen.

Secondary lymphoid organ macrophages are involved in the establishment of innate and acquired immunity. Here, we have isolated and characterized porcine lymph node and spleen CD169(+) and spleen CD163(+) macrophages. Lymph node and spleen CD169(+) macrophages can be both identified as CD172a(+)SLA-DR(hi)CD80/86(hi)CD14(int)TLR2(+)TLR4(+).

Delivery of antigen to sialoadhesin or CD163 improves the specific immune response in pigs.

Delivery of antigens to antigen presenting cell surface receptors represents a promising strategy to improve immune response to weak immunogenic antigens. We have analyzed the potential of porcine sialoadhesin (Sn) and CD163 as antigen targeting receptors using mouse Igs as surrogate antigens. Sn and CD163 are two endocytic receptors mainly expressed on macrophages located in antigen-sampling zones of secondary lymphoid organs.

Porcine monocyte subsets differ in the expression of CCR2 and in their responsiveness to CCL2.

Monocyte subsets have been shown to differ in the pattern of chemokine receptor expression and their migratory properties, both in human and mouse. Previously we have characterized in the swine several monocyte subpopulations, based on the expression of CD163, Tük4 and SLA-II, which share features with the populations described in human and mouse. Here, we have analysed the expression of different chemokine receptors in the CD163-Tük4+SLA-II- and CD163+Tük4-SLA-II+ populations of porcine monocytes.

Targeting to porcine sialoadhesin receptor improves antigen presentation to T cells.

Antibody-mediated targeting of antigen to specific antigen presenting cells (APC) receptors is an attractive strategy to enhance T cell immune responses to weak immunogenic antigens. Here, we describe the characterization of two monoclonal antibodies (mAb) against different epitopes of porcine sialoadhesin (Sn) and evaluate in vitro the potential of targeting this receptor for delivery of antigens to APC for T cell stimulation. The specificity of these mAb was determined by amino acid sequence analysis of peptides derived from the affinity purified antigen.