Successful peficitinib monotherapy for the new-onset skin manifestations of rheumatoid vasculitis after long-term treatment with tocilizumab for rheumatoid arthritis.

Rheumatoid vasculitis (RV) is a severe extra-articular systemic manifestation of rheumatoid arthritis (RA). Its prevalence has been decreasing for decades because of improved early diagnosis of RA and advances in RA treatment, but it remains a life-threatening disease. The standard treatment for RV has been a glucocorticoid and disease-modifying antirheumatic drugs. Biological agents, including antitumour necrosis factor inhibitors, are also recommended for refractory cases. However, there are no reports of Janus kinase (JAK) inhibitor use in RV. We experienced a case of an 85-year-old woman with a 57-year history of RA who had been treated with tocilizumab for 9 years after receiving three different biological agents over 2 years. Her RA seemed to be in remission in her joints, and her serum C-reactive protein had decreased to 0.0 mg/dL, but she developed multiple cutaneous leg ulcers associated with RV. Because of her advanced age, we changed her RA treatment from tocilizumab to the JAK inhibitor peficitinib in monotherapy, after which the ulcers improved within 6 months. This is the first report to indicate that peficitinib is a potential treatment option for RV that can be used in monotherapy without glucocorticoids or other immunosuppressants.

Bone and cartilage repair by transplantation of induced pluripotent stem cells in murine joint defect model.

The establishment of cartilage regenerative medicine has been an important issue in the clinical field, because cartilage has the poor ability of self-repair. Currently, tissue engineering using autologous chondrocytes has risen, but we should investigate more appropriate cell sources that can be obtained without any quantitative limitation. In this study, we focused on induced pluripotent stem (iPS) cells, in which the ethical hurdle does not seem higher than that of embryonic stem cells. Mouse iPS cells were transplanted into the mouse joint defect model of the knee. Strains of the transplants and hosts were arranged to be either closest (homology 75% in genetic background) or identical (100%). For transplantation, we embedded the iPS cells within the collagen hydrogel in order to obtain the effective administration of the cells into defects, which induced the differentiation of the iPS cells. At 8 weeks of transplantation, although the iPS cells with a 75% homology to the host in the genetic background tended to form teratoma, those of 100% showed a joint regeneration. GFP immunohistochemistry proved that the transplanted iPS cells were responsible for the bone and cartilage repair. Taking these results together, the iPS cells are regarded as a promising cell source for the cartilage tissue engineering.