title: High mortality of juvenile gilthead sea bream (Sparus aurata) from photobacteriosis is associated with alternative macrophage activation and anti-inflammatory response: results of gene expression profiling of early responses in the head kidney.
abstract: The halophilic bacterium Photobacterium damselae subsp. piscicida (Phdp) represents a substantial health problem for several fish species in aquaculture. Bacteria that reside free and inside phagocytes cause acute and chronic forms of photobacteriosis. Infections of juveniles rapidly kill up to 90-100% fish. Factors underlying failure of the immune protection against bacteria remain largely unknown. The reported study used a transcriptomic approach to address this issue. Juvenile sea breams (0.5 g) were challenged by immersion in salt water containing 2.89 × 10(8) CFU of a virulent Phdp and the head kidney was sampled after 24- and 48-h. Analyses were performed using the second version of a 44 k oligonucleotide DNA microarray that represents 19,734 sea bream unique transcripts and covers diverse immune pathways. Expression changes of selected immune genes were validated with qPCR. Results suggested rapid recognition of the pathogen, as testified by up-regulation of lectins and antibacterial proteins (bactericidal permeability-increasing protein lectins, lysozyme, intracellular and extracellular proteases), chemokines and chemokine receptors. Increased expression of proteins involved in iron and heme metabolism also could be a response against bacteria that are dependent on iron. However, negative regulators of immune/inflammatory response were preponderant among the up-regulated genes. A remarkable finding was the increased expression of IL-10 in concert with up-regulation of arginase I and II and proteins of the polyamine biosynthesis pathway that diverts the arginine flux from the production of reactive nitrogen species. Such expression changes are characteristic for alternatively activated macrophages that do not develop acute inflammatory responses. Immune suppression can be induced by the host to reduce tissue damages or by the pathogen to evade host response.
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, viale dell'Università 16, 35020 Legnaro, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Pellizzari
authors.forename: Aleksei
authors.initials: A
authors.lastname: Krasnov
authors.forename: Sergey
authors.initials: S
authors.lastname: Afanasyev
authors.forename: Nicola
authors.initials: N
authors.lastname: Vitulo
authors.forename: Rafaella
authors.initials: R
authors.lastname: Franch
authors.forename: Sara
authors.initials: S
authors.lastname: Pegolo
authors.forename: Tomaso
authors.initials: T
authors.lastname: Patarnello
authors.forename: Luca
authors.initials: L
authors.lastname: Bargelloni
mesh_terms: D000818:Animals; D001483:Base Sequence; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology / Q000401:mortality; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling / Q000662:veterinary; D005786:Gene Expression Regulation; D016905:Gram-Negative Bacterial Infections / Q000276:immunology / Q000382:microbiology / Q000401:mortality / Q000662:veterinary*; D060226:Head Kidney / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D008262:Macrophage Activation; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary; D010776:Photobacterium / Q000276:immunology* / Q000472:pathogenicity; D016133:Polymerase Chain Reaction / Q000662:veterinary; D021541:Sea Bream / Q000235:genetics* / Q000378:metabolism; D017385:Sequence Homology; D014774:Virulence
chemical_list: D029941:Fish Proteins