Francesca R Santoni de Sio1, Laura Passerini2, Silvia Restelli2, Maria Maddalena Valente2, Aleksandar Pramov3, Maria Elena Maccari4, Francesca Sanvito5, Maria Grazia Roncarolo6, Matthew Porteus6, Rosa Bacchetta7. 1. San Raffaele Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan, Italy. Electronic address: santonidesio.francesca@hsr.it. 2. San Raffaele Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan, Italy. 3. University Center for Statistics in the Biomedical Sciences (CUSSB), San Raffaele Vita-Salute University, Milan, Italy. 4. School of Medicine, San Raffaele Vita-Salute University, Milan, Italy. 5. Division of Pathology, IRCCS San Raffaele Scientific Institute, Milan, Italy. 6. Division of Stem Cell Transplantation and Regenerative Medicine, Department of Pediatrics, Stanford School of Medicine, Stanford, Calif; Institute of Stem Cell Biology and Regenerative Medicine, Stanford School of Medicine, Stanford, Calif. 7. San Raffaele Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan, Italy; Division of Stem Cell Transplantation and Regenerative Medicine, Department of Pediatrics, Stanford School of Medicine, Stanford, Calif. Electronic address: rosab@stanford.edu.
Abstract
BACKGROUND: Forkhead box P3 (FOXP3) is a key transcription factor in regulatory T (Treg) cell function. FOXP3 gene mutations cause immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, a fatal autoimmune syndrome. FOXP3 has also been proposed to act in effector T (Teff) cells, but to date, this role has not been confirmed. OBJECTIVE: We sought to evaluate the effect of reduced FOXP3 expression on human Treg and Teff cell development and correlate it with IPEX syndrome immune pathology. METHODS: We developed a model of humanized mice (huMice) in which the human hematopoietic system is stably knocked down or knocked out for the FOXP3 gene (knockdown [KD]/knockout [KO] huMice). RESULTS: Because FOXP3-KD/KO was not 100% effective, residual FOXP3 expression in hematopoietic stem progenitor cells was sufficient to give rise to Treg cells with normal expression of FOXP3. However, numerous defects appeared in the Teff cell compartment. Compared with control mice, FOXP3-KD/KO huMice showed altered thymocyte differentiation, with KD/KO thymocytes displaying significantly reduced T-cell receptor (TCR) signaling strength and increased TCR repertoire diversity. Peripheral KD/KO Teff cells were expanded and showed signs of homeostatic proliferation, such as a significantly contracted TCR repertoire, a severely reduced naive compartment, decreased telomeric repeat-binding factor 2 expression, and a skew toward a TH2 profile, resembling an aged immune system. Consistent with results in FOXP3-KD/KO huMice, analysis of patients with IPEX syndrome provided evidence of defects in the Teff cell compartment at both the thymic and peripheral levels. CONCLUSIONS: These findings support an intrinsic role for human FOXP3 in controlling thymocyte maturation and peripheral expansion of Teff cells and reveal a previously undescribed pathogenic mechanism through an altered Teff cell compartment in patients with IPEX syndrome.
BACKGROUND:Forkhead box P3 (FOXP3) is a key transcription factor in regulatory T (Treg) cell function. FOXP3 gene mutations cause immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, a fatal autoimmune syndrome. FOXP3 has also been proposed to act in effector T (Teff) cells, but to date, this role has not been confirmed. OBJECTIVE: We sought to evaluate the effect of reduced FOXP3 expression on human Treg and Teff cell development and correlate it with IPEX syndrome immune pathology. METHODS: We developed a model of humanized mice (huMice) in which the human hematopoietic system is stably knocked down or knocked out for the FOXP3 gene (knockdown [KD]/knockout [KO] huMice). RESULTS: Because FOXP3-KD/KO was not 100% effective, residual FOXP3 expression in hematopoietic stem progenitor cells was sufficient to give rise to Treg cells with normal expression of FOXP3. However, numerous defects appeared in the Teff cell compartment. Compared with control mice, FOXP3-KD/KO huMice showed altered thymocyte differentiation, with KD/KO thymocytes displaying significantly reduced T-cell receptor (TCR) signaling strength and increased TCR repertoire diversity. Peripheral KD/KO Teff cells were expanded and showed signs of homeostatic proliferation, such as a significantly contracted TCR repertoire, a severely reduced naive compartment, decreased telomeric repeat-binding factor 2 expression, and a skew toward a TH2 profile, resembling an aged immune system. Consistent with results in FOXP3-KD/KO huMice, analysis of patients with IPEX syndrome provided evidence of defects in the Teff cell compartment at both the thymic and peripheral levels. CONCLUSIONS: These findings support an intrinsic role for humanFOXP3 in controlling thymocyte maturation and peripheral expansion of Teff cells and reveal a previously undescribed pathogenic mechanism through an altered Teff cell compartment in patients with IPEX syndrome.
Authors: M Goodwin; E Lee; U Lakshmanan; S Shipp; L Froessl; F Barzaghi; L Passerini; M Narula; A Sheikali; C M Lee; G Bao; C S Bauer; H K Miller; M Garcia-Lloret; M J Butte; A Bertaina; A Shah; M Pavel-Dinu; A Hendel; M Porteus; M G Roncarolo; R Bacchetta Journal: Sci Adv Date: 2020-05-06 Impact factor: 14.136