1. Concurrent host-pathogen gene expression in the lungs of pigs challenged with Actinobacillus pleuropneumoniae
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Kirstine Klitgaard, Tim Kåre Jensen, Peter M. H. Heegaard, Mette Sif Hansen, Kerstin Skovgaard, and Louise Brogaard
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36002, Medical and clinical microbiology - Bacteriology ,Medical Sciences ,Swine ,virulence factors ,03502, Genetics - General ,iron 7439-89-6 metabolism ,pig TLR4 gene [Suidae] expression ,laser capture microdissection laboratory techniques, histology and cytology techniques ,interleukin-1B IL-1B proinflammatory cytokine ,EXPERIMENTAL-INFECTION ,Actinobacillus Infections ,interleukin-6 IL-6 proinflammatory cytokine ,Respiratory infection ,histopathological examination laboratory techniques, histology and cytology techniques ,10069, Biochemistry studies - Minerals ,BIOTECHNOLOGY ,high-throughput RT-qPCR laboratory techniques, genetic techniques ,Pathogen ,Lung ,Regulation of gene expression ,Swine Diseases ,16006, Respiratory system - Pathology ,Innate immunity ,Pleuropneumonia ,biology ,INDUCTION ,IRON ,Actinobacillus pleuropneumoniae ,pig MD2 gene [Suidae] expression ,lipoprotein synthesis ,Laser capture microdissection ,RNA, Bacterial ,lipopolysaccharide synthesis ,10068, Biochemistry studies - Carbohydrates ,pleuropneumonia Pleuropneumonia (MeSH) respiratory system disease pathology, mortality ,Infection ,exotoxins ,Research Article ,Artiodactyla Mammalia Vertebrata Chordata Animalia (Animals, Artiodactyls, Chordates, Mammals, Nonhuman Vertebrates, Nonhuman Mammals, Vertebrates) - Suidae [85740] pig common host, commercial species ,pig CD14 gene [Suidae] expression ,Transcriptional analysis ,Biotechnology ,Veterinary Medicine ,medicine.medical_specialty ,ACUTE-PHASE RESPONSE ,GENETICS ,Virulence Factors ,PROTEINS ,mRNA ,38002, Veterinary science - General and methods ,Virulence ,High-throughput RT-qPCR ,Microbiology ,16004, Respiratory system - Physiology and biochemistry ,Molecular Genetics ,Bacterial Proteins ,Molecular genetics ,03506, Genetics - Animal ,interleukin-8 IL-8 proinflammatory cytokine ,medicine ,Genetics ,Animals ,10062, Biochemistry studies - Nucleic acids, purines and pyrimidines ,peptidoglycan synthesis ,GRAM-NEGATIVE BACTERIA ,17002, Endocrine - General ,lungs respiratory system ,Innate immune system ,10064, Biochemistry studies - Proteins, peptides and amino acids ,pathogen-associated molecular patterns ,Biochemistry and Molecular Biophysics ,12502, Pathology - General ,IDENTIFICATION ,RECEPTOR ,Host-pathogen interactions ,pig LBP gene [Suidae] expression ,Gene Expression Profiling ,31500, Genetics of bacteria and viruses ,Gene Expression Regulation, Bacterial ,biology.organism_classification ,38004, Veterinary science - Pathology ,PULMONARY-LESIONS ,Gene expression profiling ,pig MYD88 gene [Suidae] expression ,31000, Physiology and biochemistry of bacteria ,Immunology ,RNA ,10066, Biochemistry studies - Lipids ,Facultatively Anaerobic Gram-Negative Rods Eubacteria Bacteria Microorganisms (Bacteria, Eubacteria, Microorganisms) - Pasteurellaceae [06703] Actinobacillus pleuropneumoniae species pathogen - Abstract
Background Actinobacillus pleuropneumoniae causes pleuropneumonia in pigs, a disease which is associated with high morbidity and mortality, as well as impaired animal welfare. To obtain in-depth understanding of this infection, the interplay between virulence factors of the pathogen and defense mechanisms of the porcine host needs to be elucidated. However, research has traditionally focused on either bacteriology or immunology; an unbiased picture of the transcriptional responses can be obtained by investigating both organisms in the same biological sample. Results Host and pathogen responses in pigs experimentally infected with A. pleuropneumoniae were analyzed by high-throughput RT-qPCR. This approach allowed concurrent analysis of selected genes encoding proteins known or hypothesized to be important in the acute phase of this infection. The expression of 17 bacterial and 31 porcine genes was quantified in lung samples obtained within the first 48 hours of infection. This provided novel insight into the early time course of bacterial genes involved in synthesis of pathogen-associated molecular patterns (lipopolysaccharide, peptidoglycan, lipoprotein) and genes involved in pattern recognition (TLR4, CD14, MD2, LBP, MYD88) in response to A. pleuropneumoniae. Significant up-regulation of proinflammatory cytokines such as IL1B, IL6, and IL8 was observed, correlating with protein levels, infection status and histopathological findings. Host genes encoding proteins involved in iron metabolism, as well as bacterial genes encoding exotoxins, proteins involved in adhesion, and iron acquisition were found to be differentially expressed according to disease progression. By applying laser capture microdissection, porcine expression of selected genes could be confirmed in the immediate surroundings of the invading pathogen. Conclusions Microbial pathogenesis is the product of interactions between host and pathogen. Our results demonstrate the applicability of high-throughput RT-qPCR for the elucidation of dual-organism gene expression analysis during infection. We showed differential expression of 12 bacterial and 24 porcine genes during infection and significant correlation of porcine and bacterial gene expression. This is the first study investigating the concurrent transcriptional response of both bacteria and host at the site of infection during porcine respiratory infection. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1557-6) contains supplementary material, which is available to authorized users.
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