Pluripotent stem cell models of Blau syndrome reveal an IFN-γ–dependent inflammatory response in macrophages

Publication date: Available online 3 June 2017
Source:Journal of Allergy and Clinical Immunology
Author(s): Sanami Takada, Naotomo Kambe, Yuri Kawasaki, Akira Niwa, Fumiko Honda-Ozaki, Kazuki Kobayashi, Mitsujiro Osawa, Ayako Nagahashi, Katsunori Semi, Akitsu Hotta, Isao Asaka, Yasuhiro Yamada, Ryuta Nishikomori, Toshio Heike, Hiroyuki Matsue, Tatsutoshi Nakahata, Megumu K. Saito
BackgroundBlau syndrome, or early-onset sarcoidosis, is a juvenile-onset systemic granulomatosis associated with a mutation in nucleotide-binding oligomerization domain 2 (NOD2). The underlying mechanisms of Blau syndrome leading to autoinflammation are still unclear, and there is currently no effective specific treatment for Blau syndrome.ObjectivesTo elucidate the mechanisms of autoinflammation in patients with Blau syndrome, we sought to clarify the relation between disease-associated mutant NOD2 and the inflammatory response in human samples.MethodsBlau syndrome–specific induced pluripotent stem cell (iPSC) lines were established. The disease-associated NOD2 mutation of iPSCs was corrected by using a CRISPR-Cas9 system to precisely evaluate the in vitro phenotype of iPSC-derived cells. We also introduced the same NOD2 mutation into a control iPSC line. These isogenic iPSCs were then differentiated into monocytic cell lineages, and the statuses of nuclear factor κB pathway and proinflammatory cytokine secretion were investigated.ResultsIFN-γ acted as a priming signal through upregulation of NOD2. In iPSC-derived macrophages with mutant NOD2, IFN-γ treatment induced ligand-independent nuclear factor κB activation and proinflammatory cytokine production. RNA sequencing analysis revealed distinct transcriptional profiles of mutant macrophages both before and after IFN-γ treatment. Patient-derived macrophages demonstrated a similar IFN-γ–dependent inflammatory response.ConclusionsOur data support the significance of ligand-independent autoinflammation in the pathophysiology of Blau syndrome. Our comprehensive isogenic disease-specific iPSC panel provides a useful platform for probing therapeutic and diagnostic clues for the treatment of patients with Blau syndrome.

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