engleski

Unwanted guest - a rat model for studying early immune response to an unusual human pathogen, Anisakis pegreffii

Background: Anisakiasis, a zoonotic disease caused by Anisakis spp. larvae, represents a rising public health problem. Presentation of the disease is variable with unspecific gastrointestinal and/or allergic symptoms, accounting for the high number of misdiagnosed cases. Objectives: To better understand the onset of anisakiasis in Sprague-Dawley rats experimentally infected with Anisakis pegreffii, we aimed at characterising early cellular and molecular (6-72 h p.i.) immune response in affected tissues and general regulatory mechanisms. Materials and Methods: Two experiments were performed on 35 and 10 male rats, respectively, and each animal was intubated by the gastric probe with 10 live A. pegreffii larvae or 1.5 mL of saline (external control). At predefined time points, animals were sacrificed and tissues with visible lesions were processed for i) Illumina NextSeq 500 paired-end sequencing, ii) target genes and microRNA expression analysis, iii) histopathological evaluation (HE, IHC, TEM), and iv) global DNA methylation quantification. Results: In total, there were 1372 differentially expressed (DE) genes in the Anisakis-infected rat stomach tissues and 1633 DE genes in the muscle tissues. Il6, Il1b, and Ccl3 showed particularly strong expression in the stomach and visceral adipose tissues. In total, three microRNAs were differentially expressed. Histopathology revealed severe inflammatory/haemorrhagic lesions in stomach tissues, dominated by neutrophils and macrophages. Different numbers of CD3+, CD4+, CD68+, iNOS+ and S100A8/A9+ cells were found in stomach, intestine, and muscle tissues. TEM revealed the presence of eosinophils in the inflammatory infiltrate with a lack of mast cells and diffuse areas of tissue necrosis, particularly in muscle tissues. No changes in global DNA methylation were observed between infected and non-infected tissues. Conclusions: Anisakis infection induces strong immune responses in infected rats with marked induction of specific proinflammatory cytokines and miRNA expression, which seems to favour the activation of the interleukin 17 signalling pathway and the development of the T helper-17 response.

Accidental host ; Anisakiasis ; Anisakis spp. ; Transcriptomics ; miRNA ; histology ; inflammation

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