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Eskandari SK, Allos H, Al Dulaijan BS, Melhem G, Sulkaj I, Alhaddad JB, Saad AJ, Deban C, Chu P, Choi JY, Kollar B, Pomahac B, Riella LV, Berger SP, Sanders JSF, Lieberman J, Li L, Azzi JR. mTORC1 Inhibition Protects Human Regulatory T Cells From Granzyme-B-Induced Apoptosis. Front Immunol 2022; 13:899975. [PMID: 35757726 PMCID: PMC9229986 DOI: 10.3389/fimmu.2022.899975] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 05/05/2022] [Indexed: 01/17/2023] Open
Abstract
Regulatory T cells (Tregs) have shown great promise as a means of cellular therapy in a multitude of allo- and auto-immune diseases—due in part to their immunosuppressive potency. Nevertheless, the clinical efficacy of human Tregs in patients has been limited by their poor in vivo homeostasis. To avert apoptosis, Tregs require stable antigenic (CD3ζ/T-cell-receptor-mediated), co-stimulatory (CD28-driven), and cytokine (IL-2-dependent) signaling. Notably, this sequence of signals supports an activated Treg phenotype that includes a high expression of granzymes, particularly granzyme B (GrB). Previously, we have shown that aside from the functional effects of GrB in lysing target cells to modulate allo-immunity, GrB can leak out of the intracellular lysosomal granules of host Tregs, initiating pro-apoptotic pathways. Here, we assessed the role of inhibiting mechanistic target of rapamycin complex 1 (mTORC1), a recently favored drug target in the transplant field, in regulating human Treg apoptosis via GrB. Using ex vivo models of human Treg culture and a humanized mouse model of human skin allotransplantation, we found that by inhibiting mTORC1 using rapamycin, intracytoplasmic expression and functionality of GrB diminished in host Tregs; lowering human Treg apoptosis by in part decreasing the phosphorylation of S6K and c-Jun. These findings support the already clinically validated effects of mTORC1 inhibition in patients, most notably their stabilization of Treg bioactivity and in vivo homeostasis.
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Affiliation(s)
- Siawosh K Eskandari
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.,Division of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Hazim Allos
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Basmah S Al Dulaijan
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Gandolina Melhem
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Ina Sulkaj
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.,Graduate Program in Immunology, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Juliano B Alhaddad
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Anis J Saad
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Christa Deban
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Philip Chu
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - John Y Choi
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Branislav Kollar
- Division of Plastic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.,Department of Plastic and Hand Surgery, University of Freiburg Medical Center, Medical Faculty of the University of Freiburg, Freiburg, Germany
| | - Bohdan Pomahac
- Division of Plastic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.,Division of Plastic and Reconstructive Surgery, Smilow Cancer Hospital, Yale School of Medicine, New Haven, CT, United States
| | - Leonardo V Riella
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.,Center of Transplantation Sciences, Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
| | - Stefan P Berger
- Division of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Jan S F Sanders
- Division of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Judy Lieberman
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States.,Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, United States
| | - Li Li
- Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - Jamil R Azzi
- Transplantation Research Center, Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.,Division of Nephrology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
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