Intelectin 3 is dispensable for resistance against a mycobacterial infection in zebrafish (Danio rerio)

Markus J T Ojanen,Juha A E Määttä,Meri I E Uusi-Mäkelä,Vesa P Hytönen,Anni K Saralahti,Niklas Kähkönen,Sanna-Kaisa E Harjula,Mika Rämet,Kaisa E Oksanen,Marko Pesu

doi:10.1038/s41598-018-37678-1

Markus J T Ojanen, Juha A E Määttä + Show 8 more

Open Access

https://doi.org/10.1038/s41598-018-37678-1

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Abstract

Tuberculosis is a multifactorial bacterial disease, which can be modeled in the zebrafish (Danio rerio). Abdominal cavity infection with Mycobacterium marinum, a close relative of Mycobacterium tuberculosis, leads to a granulomatous disease in adult zebrafish, which replicates the different phases of human tuberculosis, including primary infection, latency and spontaneous reactivation. Here, we have carried out a transcriptional analysis of zebrafish challenged with low-dose of M. marinum, and identified intelectin 3 (itln3) among the highly up-regulated genes. In order to clarify the in vivo significance of Itln3 in immunity, we created nonsense itln3 mutant zebrafish by CRISPR/Cas9 mutagenesis and analyzed the outcome of M. marinum infection in both zebrafish embryos and adult fish. The lack of functional itln3 did not affect survival or the mycobacterial burden in the zebrafish. Furthermore, embryonic survival was not affected when another mycobacterial challenge responsive intelectin, itln1, was silenced using morpholinos either in the WT or itln3 mutant fish. In addition, M. marinum infection in dexamethasone-treated adult zebrafish, which have lowered lymphocyte counts, resulted in similar bacterial burden in both WT fish and homozygous itln3 mutants. Collectively, although itln3 expression is induced upon M. marinum infection in zebrafish, it is dispensable for protective mycobacterial immune response.

Highlights

Tuberculosis is an epidemic multifactorial disease caused by Mycobacterium tuberculosis[1]
In order to identify genes involved in the host immune response against mycobacteria, we used the zebrafish M. marinum infection model and conducted a genome-wide gene expression analysis using the microarray platform
The genetics of the host affect the outcome of a M. tuberculosis infection, i.e. the development of active tuberculosis[4]

Summary

Introduction

Tuberculosis is an epidemic multifactorial disease caused by Mycobacterium tuberculosis[1]. Critical genes of the adaptive immunity required for the mycobacterial immune response such as interferon gamma (IFNG)[5,6] and interleukin 12 (IL12)[7,8] were identified already in the 1980’s and 1990’s, respectively The importance of these genes has later been verified in human tuberculosis patients[9] and by using experimental gene knockout mouse models of tuberculosis[10,11,12,13]. Voehringer et al, used transgenic mice with lung-specific ITLN1 and ITLN2 over-expression to study the effects of these proteins in the mouse infection models of the parasite Nippostrongylus brasiliensis and the M. tuberculosis bacterium[35]. Zebrafish can be modified genetically with the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) mutagenesis[47,48], which allows disease modeling using reverse genetics, some genes appear difficult to target successfully[49]

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