Keio University · Medicine
Professor Hayato Takahashi's research lab focuses on the immunological mechanisms underlying autoimmune diseases, particularly pemphigus vulgaris, a severe blistering disorder driven by autoantibodies against desmoglein 3. The lab investigates the roles of antigen-specific T cells and B cell interactions in autoimmunity, using innovative mouse models to dissect the pathogenicity of T cell clones and the induction of autoantibody production. They also explore peripheral tolerance mechanisms and the interplay between autoimmunity and viral reactivation, such as in drug-induced hypersensitivity syndrome. Their work bridges basic immunology with clinical pathology, offering insights into disease pathogenesis and potential therapeutic targets.
Figures are computed from collected data and may differ slightly.
Pemphigus vulgaris (PV) is a severe autoimmune disease involving blistering of the skin and mucous membranes. It is caused by autoantibodies against desmoglein 3 (Dsg3), an adhesion molecule critical for maintaining epithelial integrity in the skin, oral mucosa, and esophagus. Knowing the antigen targeted by the autoantibodies renders PV a valuable model of autoimmunity. Recently, a role for Dsg3-specific CD4+ T helper cells in autoantibody production was demonstrated in a mouse model of PV, but
Autoreactive T cells are thought to be involved in the pathogenesis of autoimmune diseases, but evidence for their direct pathogenicity is almost lacking. Herein we established a unique system for evaluating the in vivo pathogenicity of desmoglein 3 (Dsg3)-reactive T cells at a clonal level in a mouse model for pemphigus vulgaris (PV), an autoimmune blistering disease induced by anti-Dsg3 autoantibodies. Dsg3-reactive CD4(+) T cell lines generated in vitro were adoptively transferred into Rag-2(
The development of naive B cells into IgG-producing memory B cells requires cognate T cell-B cell interaction in Ag-specific immune responses. It is unknown whether a single T cell clone is sufficient or whether multiple clones are necessary to induce polyclonal IgG production in vivo. We addressed this issue using a mouse model of pemphigus vulgaris, a fatal autoimmune blistering skin disease caused by IgG autoantibodies against desmoglein (Dsg) 3. We previously isolated several Dsg3-reactive T
We describe a 27-year-old Japanese female with a recurrent nodule on the left big toe and local bone invasion. Histopathologically, the tumor consisted of nests of atypical cells with few mitotic cells, which partly formed gland-like structures. Areas of myxoid degeneration, positive for Alcian blue staining and that did not stain after they were digested with hyaluronidase, were prominent in the matrix among tumor cells. Positive staining was noted in tumor cells for cytokeratin (AE1+AE3), S-10
Antigen-specific peripheral tolerance is crucial to prevent the development of organ-specific autoimmunity. However, its function decoupled from thymic tolerance remains unclear. We used desmoglein 3 (Dsg3), a pemphigus antigen expressed in keratinocytes, to analyze peripheral tolerance under physiological antigen-expression conditions. Dsg3-deficient thymi were transplanted into athymic mice to create a unique condition in which Dsg3 was expressed only in peripheral tissue but not in the thymus
Drug-induced hypersensitivity syndrome (DIHS) is one of the most severe drug adverse reactions, with characteristic biphasic symptoms. Reactivation of human herpesvirus-6 (HHV-6) is frequently observed, although the cause of DIHS is still unknown. A patient developed DIHS during treatment with diaminodiphenylsulphone for pemphigus foliaceus. The number of lymphocytes in his peripheral blood, and titres of serum total IgG and IgM and anti-desmoglein1 antibody transiently decreased just before rea
Interleukin-27 (IL-27) is an immunoregulatory cytokine whose essential function is to limit immune responses. We found that the gene encoding cholesterol 25-hydroxylase (Ch25h) was induced in CD4<sup>+</sup> T cells by IL-27, enhanced by transforming growth factor–β (TGF-β), and antagonized by T-bet. Ch25h catalyzes cholesterol to generate 25-hydroxycholesterol (25OHC), which was subsequently released to the cellular milieu, functioning as a modulator of T cell response. Extracellular 25OHC supp
Autoimmune diseases are devastating conditions in which the immune system is directed against the host, leading to life-threatening destruction of organs. Although autoantigens are ill-defined in most autoimmune diseases, this is not the case in the skin. Autoimmune bullous diseases have been extensively studied with detailed characterization of autoantigens, the epitopes that are targeted, and the mechanisms of action that mediate autoimmune tissue destruction. Pemphigus is an autoimmune bullou
Pemphigus is a life-threatening autoimmune bullous disease mediated by anti-desmoglein IgG autoantibodies. Pemphigus is mainly classified into three subtypes: pemphigus vulgaris, pemphigus foliaceus, and paraneoplastic pemphigus. The pathogenicity of autoantibodies has been extensively studied. Anti-human CD20 antibody therapy targeting B cells emerged as a more effective treatment option compared to conventional therapy for patients with an intractable disease. On the other hand, autoreactive T
We report a 73-year-old Japanese female who developed IgG autoantibodies against BP180 as well as desmoglein 3 (Dsg3). She showed tense blisters on the extremities without apparent mucosal involvement and a skin biopsy indicated subepidermal blisters with eosinophilic spongiosis. Her clinical and histologic features indicated the diagnosis of bullous pemphigoid while anti-Dsg3 IgG might not show an apparent pathogenic effect. Interestingly, titres of anti-Dsg3 IgG fluctuated in parallel with tho
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