Portal de Periódicos da CAPES

Leishmaniasis: the act of transmission

2021; Elsevier BV; Volume: 37; Issue: 11 Linguagem: Inglês

10.1016/j.pt.2021.07.003

1471-5007

Tiago D. Serafim, Iliano V. Coutinho-Abreu, Ranadhir Dey, Ryan Kissinger, Jesús G. Valenzuela, Fabiano Oliveira, Shaden Kamhawi,

Viral Infections and Vectors

The feeding behavior of sand flies is intimately connected to vector competence and success of Leishmania transmission. In the sand fly, a postinfected blood meal prevents loss of parasites and promotes transmissible infections. More blood meals increase sand fly infectiousness through retroleptomonad parasites. In addition, prolonged host bleeding induces heme oxygenase-1 (HO-1) in macrophages, which dampens inflammation and promotes disease tolerance. Sand fly gut microbiota is critical to Leishmania development and promotes transmission through host inflammasome-mediated interleukin (IL)-1β that amplifies neutrophil recruitment. Sand fly yellow proteins in saliva are bona fide neutrophil chemoattractants that promote infection. Neutrophils are central to acute inflammation caused by bite-specific mediators, but dermal resident macrophages are gaining attention as participants that harbor Leishmania parasites early in infection. The contribution of vector transmission to pathogen establishment is largely underrated. For Leishmania, transmission by sand flies is critical to early survival involving an irreproducible myriad of parasite, vector, and host molecules acting in concert to promote infection at the bite site. Here, we review recent breakthroughs that provide consequential insights into how vector transmission of Leishmania unfolds. We focus on recent work pertaining to the effect of gut microbiota, sand fly immunity, and changes in metacyclogenesis upon multiple blood meals, on Leishmania development and transmission. We also explore how sand fly saliva, egested parasite molecules and vector gut microbiota, and bleeding have been implicated in modulating the early innate host response to Leishmania, affecting the phenotype of neutrophils and monocytes arriving at the bite site. The contribution of vector transmission to pathogen establishment is largely underrated. For Leishmania, transmission by sand flies is critical to early survival involving an irreproducible myriad of parasite, vector, and host molecules acting in concert to promote infection at the bite site. Here, we review recent breakthroughs that provide consequential insights into how vector transmission of Leishmania unfolds. We focus on recent work pertaining to the effect of gut microbiota, sand fly immunity, and changes in metacyclogenesis upon multiple blood meals, on Leishmania development and transmission. We also explore how sand fly saliva, egested parasite molecules and vector gut microbiota, and bleeding have been implicated in modulating the early innate host response to Leishmania, affecting the phenotype of neutrophils and monocytes arriving at the bite site. sand flies that complete a gonotrophic cycle before taking another blood meal, that is, they take one blood meal between egg layings. This is in contrast to discordant sand flies that do not need to complete a gonotrophic cycle before taking another blood meal, that is, they take more than one blood meal between egg layings. a member of the CXCL class of chemokines. This protein is involved in the inflammatory process and induces chemotaxis of neutrophils and other immune cells. the most abundant resident immune cell type in the skin. They are involved in resistance against pathogens, attraction of immune cells, and tissue repair. a type of extracellular vesicle that contain cell constituents, including protein, DNA, and RNA of the cells that produced them. a cell-surface, seven-transmembrane receptor that binds extracellular ligands and transmits signals inside the cell to regulate processes including cell proliferation, survival, and motility. interleukin-1 beta is a cytokine (protein) produced by macrophages, natural killer cells, monocytes, and neutrophils, that promotes inflammation. This protein is processed to its active form by the enzyme caspase 1, a component of the inflammasome. a signaling pathway in insects that is responsible for the recognition of Gram-negative bacteria and which regulates the antibacterial defense response. Janus kinase and signal transducer and activator of transcription (JAK/STAT) is a key pathway responsible for induction of the insect innate immune system and processes such as melanization and phagocytosis. a type of granulocyte which is a phagocytic white blood cell that forms part of the innate immune system and is the first type of cell to arrive at the site of infection. a protein complex inside the cells involved in the inflammatory process and responsible for cleavage of caspase 1 needed to produce active IL-1β. sand flies that support the development of multiple Leishmania species. a proteophosphoglycan-rich gel-like solution secreted by Leishmania parasites inside the sand fly gut. sand flies that support the development of one specific Leishmania species. a signaling pathway in insects that is responsible for the recognition of fungi and Gram-positive bacteria and the induction of antimicrobial peptides. the ability of a disease vector to support pathogen development to maturity, culminating in its successful transmission to a host. a measurement of the potential of a vector of disease to transmit a pathogen.