Investigation of immune-related diseases using patient-derived induced pluripotent stem cells

The precise pathogenesis of immune-related diseases remains unclear, and new effective therapeutic choices are required for the induction of remission or cure in these diseases. Basic research utilizing immune-related disease patient-derived induced pluripotent stem (iPS) cells is expected to be a promising platform for elucidating the pathogenesis of the diseases and for drug discovery. Since autoinflammatory diseases are usually monogenic, genetic mutations affect the cell function and patient-derived iPS cells tend to exhibit disease-specific phenotypes. In particular, iPS cell-derived monocytic cells and macrophages can be used for functional experiments, such as inflammatory cytokine production, and are often employed in research on patients with autoinflammatory diseases.On the other hand, the utilization of disease-specific iPS cells is less successful for research on autoimmune diseases. One reason for this is that autoimmune diseases are usually polygenic, which makes it challenging to determine which factors cause the phenotypes of patient-derived iPS cells are caused by. Another reason is that protocols for differentiating some lymphocytes associated with autoimmunity, such as CD4⁺T cells or B cells, from iPS cells have not been well established. Nevertheless, several groups have reported studies utilizing autoimmune disease patient-derived iPS cells, including patients with rheumatoid arthritis, systemic lupus erythematosus (SLE), and systemic sclerosis. Particularly, non-hematopoietic cells, such as fibroblasts and cardiomyocytes, differentiated from autoimmune patient-derived iPS cells have shown promising results for further research into the pathogenesis. Recently, our groups established a method for differentiating dendritic cells that produce interferon-alpha, which can be applied as an SLE pathological model. In summary, patient-derived iPS cells can provide a promising platform for pathological research and new drug discovery in the field of immune-related diseases.