title: PD-1 function in apoptosis of T lymphocytes in canine visceral leishmaniasis.
abstract: Dogs infected with Leishmania infantum have a reduced number of T lymphocytes. PD-1 (Programmed cell death 1) a new member of the B7-CD28 family that is expressed by immune cells, and its binding to PD-L1 (CD274) or PD-L2 (CD273) induces the deactivation or apoptosis of T cells. This study aimed to evaluate the expression of PD-1 and its ligands, as well as blocking in the induction of apoptosis in T lymphocytes, TNF-α, IL-4 and nitric oxide production by leucokocytes from PBMC and spleen and the parasite load in dogs with visceral leishmaniasis (VL). Our results showed that the expression of PD1 and its ligands was increased in CD3(+) T cells and CD21(+) B lymphocytes within the peripheral blood and splenic mononuclear cells of dogs with VL. In peripheral blood monocytes, only PD-1 ligands exhibited increased expression; however, in spleen macrophages, increased expression of both PD-1 and its ligands was observed. Levels of apoptosis in peripheral blood and splenic T lymphocytes were higher in dogs with VL compared to healthy dogs. Blocking monoclonal antibodies to PD-1 and its ligands in the culture of mononuclear cells from the peripheral blood and spleen decreased the amount of CD3(+) T lymphocyte apoptosis. The concentration of nitric oxide, TNF-α and IL-4 increased in the culture supernatants of peripheral blood mononuclear cells treated with a blocking monoclonal antibody against PD-1. The TNF-α concentration increased in the culture supernatants of splenic cells following all treatments with antibodies blocking PD-1 and its ligands; however, the amount of IL-4 increased only in the presence of a PD-1 blocking agent. Treatment with a PD-1 blocking monoclonal antibody in the mononuclear peripheral blood of dogs with VL reduced the parasite burden while increased TNF-α. We conclude that in canine visceral leishmaniasis, PD-1 and its ligands are involved in the induction of T lymphocyte apoptosis and in regulating the production of nitric oxide, TNF-α, and IL-4, as well as the parasitic load.
authors.affiliation: Faculty of Veterinary Medicine of Araçatuba, Universidade Estadual Paulista, "Julio de Mesquita Filho", FMVA/UNESP, Rua Clovis Pestana, 793, Araçatuba, São Paulo CEP 16050-680, Brazil.
authors.forename: Vanessa Marim
authors.initials: VM
authors.lastname: Chiku
authors.affiliation: Faculty of Veterinary Medicine of Araçatuba, Universidade Estadual Paulista, "Julio de Mesquita Filho", FMVA/UNESP, Rua Clovis Pestana, 793, Araçatuba, São Paulo CEP 16050-680, Brazil.
authors.forename: Kathlenn Liezbeth Oliveira
authors.initials: KL
authors.lastname: Silva
authors.affiliation: Faculty of Veterinary Medicine of Araçatuba, Universidade Estadual Paulista, "Julio de Mesquita Filho", FMVA/UNESP, Rua Clovis Pestana, 793, Araçatuba, São Paulo CEP 16050-680, Brazil.
authors.forename: Breno Fernando Martins
authors.initials: BF
authors.lastname: de Almeida
authors.affiliation: Faculty of Veterinary Medicine of Araçatuba, Universidade Estadual Paulista, "Julio de Mesquita Filho", FMVA/UNESP, Rua Clovis Pestana, 793, Araçatuba, São Paulo CEP 16050-680, Brazil.
authors.forename: Gabriela Lovizutto
authors.initials: GL
authors.lastname: Venturin
authors.affiliation: Faculty of Veterinary Medicine of Araçatuba, Universidade Estadual Paulista, "Julio de Mesquita Filho", FMVA/UNESP, Rua Clovis Pestana, 793, Araçatuba, São Paulo CEP 16050-680, Brazil.
authors.forename: Aline Aparecida Correa
authors.initials: AA
authors.lastname: Leal
authors.affiliation: Faculty of Veterinary Medicine of Araçatuba, Universidade Estadual Paulista, "Julio de Mesquita Filho", FMVA/UNESP, Rua Clovis Pestana, 793, Araçatuba, São Paulo CEP 16050-680, Brazil.
authors.forename: Cleber Costa
authors.initials: CC
authors.lastname: de Martini
authors.affiliation: Department of Clinical Care, Surgery and Animal Reproduction, Laboratory of Cellular Immunology, Faculty of Veterinary Medicine of Araçatuba, Universidade Estadual Paulista, "Julio de Mesquita Filho", FMVA/UNESP, Rua Clovis Pestana, 793, Araçatuba, São Paulo CEP 16050-680, Brazil.
authors.forename: Flavia
authors.initials: F
authors.lastname: de Rezende Eugênio
authors.affiliation: Department of Clinical Care, Surgery and Animal Reproduction, Laboratory of Cellular Immunology, Faculty of Veterinary Medicine of Araçatuba, Universidade Estadual Paulista, "Julio de Mesquita Filho", FMVA/UNESP, Rua Clovis Pestana, 793, Araçatuba, São Paulo CEP 16050-680, Brazil.
authors.forename: Paulo Sergio Patto
authors.initials: PS
authors.lastname: Dos Santos
authors.affiliation: Department of Clinical Care, Surgery and Animal Reproduction, Laboratory of Cellular Immunology, Faculty of Veterinary Medicine of Araçatuba, Universidade Estadual Paulista, "Julio de Mesquita Filho", FMVA/UNESP, Rua Clovis Pestana, 793, Araçatuba, São Paulo CEP 16050-680, Brazil. Electronic address: vmflima@fmva.unesp.br.
authors.forename: Valéria Marçal Felix
authors.initials: VM
authors.lastname: de Lima
mesh_terms: D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000494:pharmacology; D057134:Antibodies, Neutralizing / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D004285:Dogs; D015847:Interleukin-4 / Q000276:immunology; D007893:Leishmania donovani / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000276:immunology* / Q000473:pathology; D008264:Macrophages / Q000276:immunology / Q000469:parasitology / Q000473:pathology; D061026:Programmed Cell Death 1 Receptor / Q000037:antagonists & inhibitors / Q000276:immunology*; D013154:Spleen / Q000276:immunology* / Q000469:parasitology / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D057134:Antibodies, Neutralizing; D061026:Programmed Cell Death 1 Receptor; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4
keywords: Apoptosis; Canine visceral leishmaniasis; PD-1 (programmed cell death 1)