High-throughput proteomic profiling of the fish liver following bacterial infection

Abstract

BackgroundHigh-throughput proteomics was used to determine the role of the fish liver in defense responses to bacterial infection. This was done using a rainbow trout (Oncorhynchus mykiss) model following infection with Aeromonas salmonicida, the causative agent of furunculosis. The vertebrate liver has multifaceted functions in innate immunity, metabolism, and growth; we hypothesize this tissue serves a dual role in supporting host defense in parallel to metabolic adjustments that promote effective immune function. While past studies have reported mRNA responses to A. salmonicida in salmonids, the impact of bacterial infection on the liver proteome remains uncharacterized in fish.ResultsRainbow trout were injected with A. salmonicida or PBS (control) and liver extracted 48 h later for analysis on a hybrid quadrupole-Orbitrap mass spectrometer. A label-free method was used for protein abundance profiling, which revealed a strong innate immune response along with evidence to support parallel rewiring of metabolic and growth systems. 3076 proteins were initially identified against all proteins (n = 71,293 RefSeq proteins) annotated in a single high-quality rainbow trout reference genome, of which 2433 were maintained for analysis post-quality filtering. Among the 2433 proteins, 109 showed significant differential abundance following A. salmonicida challenge, including many upregulated complement system and acute phase response proteins, in addition to molecules with putative functions that may support metabolic re-adjustments. We also identified novel expansions in the complement system due to gene and whole genome duplication events in salmonid evolutionary history, including eight C3 proteins showing differential changes in abundance.ConclusionsThis study provides the first high-throughput proteomic examination of the fish liver in response to bacterial challenge, revealing novel markers for the host defense response, and evidence of metabolic remodeling in conjunction with activation of innate immunity.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5092-0) contains supplementary material, which is available to authorized users.

Short-Term Supplementation of Dietary Arginine and Citrulline Modulates Gilthead Seabream (Sparus aurata) Immune Status

“…High-throughput proteomics are gaining rapid traction in teleost physiology ( 38 ), and it is well-known that there should not be an expectation of a direct relationship between head-kidney transcriptomic response and plasma protein abundance. Hence, in order to better understand the modulation capacity of Arginine and Citrulline supplementation, plasma samples were evaluated in terms of their protein content.…”

Loci associated with variation in gene expression and growth in juvenile salmon are influenced by the presence of a growth hormone transgene

“…It is likely such a broad association between expression levels and the various regulatory elements rises from the diverse pathways in which LEPTIN plays a role. SNPs associated with C3-4, another gene associated with a diversity of functions [40,41] and controlled by numerous regulatory elements [42], were also widely dispersed throughout the genome. In comparison, expression of GHR, which has a limited function in the growth hormone axis [43], was associated with just 10 SNPs in transgenic fish of which 8 were located on linkage group 4.…”

Rainbow trout (Oncorhynchus mykiss) urea cycle and polyamine synthesis gene families show dynamic expression responses to inflammation

“…To gain information on the expression of the urea cycle genes/paralogues, we quantified their mRNA expression and transcriptional responses following bacterial infection in muscle and liver. We sampled liver as a key indicator of the acute phase response [51,52] that shows a well-established response to bacterial infection, while also acting as the main site for amino acid metabolism and the urea cycle. Skeletal muscle was also selected for analysis, due to high transcript levels identified in many of the genes in the tissue distributions (see Results section 3.2.1).…”

“…Skeletal muscle was also selected for analysis, due to high transcript levels identified in many of the genes in the tissue distributions (see Results section 3.2.1). Fish were sampled 48h after infection to represent the early immune response before physiological changes due to disease could occur [51].…”