Pluripotent Stem Cell Model of Nakajo-Nishimura Syndrome Untangles Proinflammatory Pathways Mediated by Oxidative Stress

Abstract

SummaryNakajo-Nishimura syndrome (NNS) is an immunoproteasome-associated autoinflammatory disorder caused by a mutation of the PSMB8 gene. Although dysfunction of the immunoproteasome causes various cellular stresses attributed to the overproduction of inflammatory cytokines and chemokines in NNS, the underlying mechanisms of the autoinflammation are still largely unknown. To investigate and understand the mechanisms and signal pathways in NNS, we established a panel of isogenic pluripotent stem cell (PSC) lines with PSMB8 mutation. Activity of the immunoproteasome in PSMB8-mutant PSC-derived myeloid cell lines (MT-MLs) was reduced even without stimulation compared with non-mutant-MLs. In addition, MT-MLs showed an overproduction of inflammatory cytokines and chemokines, with elevated reactive oxygen species (ROS) and phosphorylated p38 MAPK levels. Treatment with p38 MAPK inhibitor and antioxidants decreased the abnormal production of cytokines and chemokines. The current PSC model revealed a specific ROS-mediated inflammatory pathway, providing a platform for the discovery of alternative therapeutic options for NNS and related immunoproteasome disorders.

High-throughput Screening with Pluripotent Stem Cells Identifies CUDC-907 as an Effective Compound for Restoring the Proinflammatory Phenotype of Nakajo-Nishimura Syndrome

“…We previously demonstrated that such MLs can be used to model the proinflammatory phenotypes of various autoinflammatory disorders [14,[28][29][30]. Combined with the current study, which successfully identified candidate compounds, we concluded that this ML-based HTS system provides a versatile platform for screening candidate compounds for treating autoinflammatory disorders.…”

“…Induced pluripotent stem cells (iPSCs) were established from the fibroblasts of NNS#1 [14]. MLs were established from iPSCs bearing mutant homozygous PSMB8 (MT-iPS-MLs), their isogenic wild-type counterpart (WT-iPS-MLs), and from KhES1 ESCs bearing the same PSMB8 mutation (MT-ES-MLs) [14].…”

“…We performed HTS to identify drug candidates for NNS. Compounds were evaluated by the inhibition rates of MCP-1 and IP-10, both of which are proinflammatory chemokines specifically elevated in NNS patients [5,14]. Although IL-6 is also specifically elevated in NNS patients, blockage of the IL-6 receptor by the administration of the anti-IL-6 receptor tocilizumab provided limited therapeutic effects [21].…”

“…It is previously reported that impaired immunoproteasome activity by this mutation causes an excessive accumulation of ubiquitinated and oxidized proteins and an elevated serum concentration of the proinflammatory cytokines and chemokines interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1) and interferon gamma-induced protein-10 (IP-10) [4]. To investigate the detailed pathophysiology of NNS, we previously established isogenic pairs (wild-type and mutant PSMB8 G201) of human pluripotent stem cells (PSCs) with or without the NNS-associated PSMB8 mutation [14]. We then established an in vitro disease model by establishing immortalized myeloid cell lines (MLs) from PSC-derived monocytic cells [15].…”

Effects of a humanized anti-human IL-6 receptor monoclonal antibody on Nakajo-Nishimura syndrome

“…Very recently, Honda-Ozaki and Kanazawa reported the pluripotent stem cell model of NNS untangles proinflammatory pathways mediated by oxidative stress and found a specific ROS-mediated inflammatory pathway, providing a platform for the discovery of alternative therapeutic options for NNS and related immunoproteasome disorders [10] . Individual case studies using iPS cells will develop new effective treatments.…”