中條・西村症候群

Nakajo-Nishimura syndrome/proteasome-associated autoinflammatory syndrome (NNS/PRAAS) is a hereditary autoinflammatory disease. Clinically, NNS/PRAAS is characterized by periodic fever, skin rash, partial lipo-muscular atrophy, and joint contractures. Among PRAAS, NNS, is genetically characterized by a homozygous founder variant in the proteasome subunit beta type 8 (PSMB8) gene encoding an inducible proteasome component β5i. To establish an in vivo animal model recapitulating NNS/PRAAS, we generated mice harboring this founder variant. In Psmb8G201V/G201V mice, the immature β5i subunit was increased and 20S proteasome activity was significantly reduced in the spleen, whereas 26S proteasome activity was preserved and ubiquitin accumulation was not apparent. Compared with wild-type mice, Psmb8G201V/G201V mice exhibited a shortened lifespan and, as they aged, showed less weight gain and adipocyte shrinkage with interstitial macrophage infiltration and cytokine production/activation. The mutant mice also manifested significantly lower proportion of T cells in total splenocytes, with higher CD4+ and lower CD8+ T cell proportions. Psmb8G201V/G201V mice shared some characteristic autoinflammatory and progeroid phenotypes as observed in NNS/PRAAS patients, although their proteasome defect pattern was distinct. Thus, Psmb8G201V/G201V mice should be useful not only for investigation of NNS/PRAAS pathogenesis but also for examining the clinical effect of candidate drugs on NNS/PRAAS and related diseases.

Multiple Sclerosis (MS) is an autoimmune and chronic disease in the brain and spinal cord. MS has inflammatory progression characterized by its hallmark inflammatory plaques. The histological and clinical characteristics of MS are shared by Experimental Autoimmune Encephalomyelitis (EAE). Genetic and environmental factors contribute to the development of MS. In EAE-MS disease, the level of proteasome subunit beta type-8 (PSMB8), encoded by the PSMB8 gene, is increased and regulates the inflammatory response in this disease. In humans, the Nakajo-Nishimura Syndrome is caused by a mutation in the gene PSMB8, a part of the immunoproteasome subunit. Therefore, special attention to wild and mutant (G210V) PSMB8 protein is imperative. In this study, we performed a 100 ns molecular dynamics (MD) simulation for wild-type PSMB8 and the mutant G210V. Then, we analyzed the fundamental and essential simulation results using another Google Colab system. The energy analysis ensures the structural deviation due to point mutation. The trajectory of the fundamental simulation (RMSD, RMSF, and Rg) describes that the G210V mutated protein is more flexible and less stable than the wild type. We observed the conformational changes due to mutation by analyzing the RMSD average linkage hierarchical clustering, total SASA, and SASA autocorrelation. The differences in the protein's overall motion and the atoms' precise location are identified by the principal component analysis, showing that the overall motion and location of the atoms are different. Our study provides valuable insights into the dynamics and structure of this protein, which can aid in further understanding its biological functions and potential implications for disease.

Histiocytoid Sweet's syndrome (HSS) is a variant of Sweet's syndrome (SS) that clinically resembles SS but differs histologically by infiltrates, predominantly composed of immature cells of the myeloid lineage. Medications such as proteasome inhibitors have been reported to cause HSS but there has been little discussion on the underlying mechanism. Here we report two cases of HSS associated with a proteasome inhibitor. Both patients were on ixazomib for the treatment of multiple myeloma and presented with acute erythematous plaques on the upper half of the body. Pathological findings were consistent with HSS. Similarities between proteasome inhibitor-induced HSS and Nakajo-Nishimura syndrome, an inherited inflammatory disease, can be identified both clinically and histologically, suggesting a potential explanation of the mechanism behind proteasome inhibitor-associated HSS.

Panniculitis was first described in the nineteenth century and is characterized by inflammation of the subcutaneous fat. It may be categorized in septal or lobular subtypes, but other histopathological features (e.g., presence of vasculitis, nature of inflammatory infiltrates, characteristics of fat necrosis) are also important for diagnostic purposes. Clinically, panniculitis is characterized by the presence of subcutaneous nodules, and both ulcerative and nonulcerative clinical subtypes have been proposed. In this review, we aimed to describe the occurrence of panniculitis in autoinflammatory disorders (AIDs) and related diseases. Among monogenic AIDs, panniculitis is common in IFN-mediated disorders. Panniculitis is a distinctive feature in proteasome-associated autoinflammatory syndromes (PRAAS), including chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome and Nakajo-Nishimura syndrome. On the other hand, erythema nodosum corresponds to the most common clinical form of panniculitis and is common in polygenic AIDs, such as Behçet's syndrome, inflammatory bowel disease, and sarcoidosis. Cytophagic histiocytic panniculitis, lipoatrophic panniculitis of children, and otulipenia are rare disorders that may also present with inflammation of the subcutaneous fat. Therefore, panniculitis can identify a specific subgroup of patients with AIDs and may potentially be regarded as a cardinal sign of autoinflammation.