scholarly journals SOCS3 Expression by Thymic Stromal Cells Is Required for Normal T Cell Development

2021 ◽  
Vol 12 ◽  
Author(s):  
Yu Gao ◽  
Ruining Liu ◽  
Chenfei He ◽  
Juan Basile ◽  
Mattias Vesterlund ◽  
...  

The suppressor of cytokine signaling 3 (SOCS3) is a major regulator of immune responses and inflammation as it negatively regulates cytokine signaling. Here, the role of SOCS3 in thymic T cell formation was studied in Socs3fl/flActin-creER mice (Δsocs3) with a tamoxifen inducible and ubiquitous Socs3 deficiency. Δsocs3 thymi showed a 90% loss of cellularity and altered cortico-medullary organization. Thymocyte differentiation and proliferation was impaired at the early double negative (CD4-CD8-) cell stage and apoptosis was increased during the double positive (CD4+CD8+) cell stage, resulting in the reduction of recent thymic emigrants in peripheral organs. Using bone marrow chimeras, transplanting thymic organoids and using mice deficient of SOCS3 in thymocytes we found that expression in thymic stromal cells rather than in thymocytes was critical for T cell development. We found that SOCS3 in thymic epithelial cells (TECs) binds to the E3 ubiquitin ligase TRIM 21 and that Trim21−/− mice showed increased thymic cellularity. Δsocs3 TECs showed alterations in the expression of genes involved in positive and negative selection and lympho-stromal interactions. SOCS3-dependent signal inhibition of the common gp130 subunit of the IL-6 receptor family was redundant for T cell formation. Together, SOCS3 expression in thymic stroma cells is critical for T cell development and for maintenance of thymus architecture.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3264-3264
Author(s):  
Susan Prockop ◽  
Ana Beesen ◽  
Aaron Myers ◽  
Richard J. O’Reilly

Abstract Successful T lymphopoiesis is essential for maintaining resistance to infection, mediating graft versus tumor activity, and as a platform for some immune based therapies. Among the most profound age-related change affecting the hemopoietic system is involution of the thymus and a decline in T cell production. Coordinated interaction of marrow-derived lymphoid progenitors with thymic stromal cells is required for successful de novo T lymphopoiesis. Current models of thymic involution indicate that aging alters the capacity of thymic stromal cells to support this de novo T cell lymphopoiesis. Loss of specific sets of thymic stromal cells, or loss of specific lympho-stromal signaling interactions may partially explain age-based impaired T cell reconstitution. Prior models examining the potential to reconstitute the aged thymus have been conducted either in vitro or in cyto-reduced hosts, and thus largely risk confounding cytotoxic damage with age-related damage. We have established an in vivo functional assessment of the ability of thymic stroma to support de novo T lymphocyte development. In the absence of radiation or chemotherapy this system supports robust thymic reconstitution after transplantation of limited numbers of T cell depleted wild type precursors. We have previously demonstrated that the capacity for reconstitution in this model system depends on the presence of normal, but empty, stromal niches. Using this model we have demonstrated that a variety of chemotherapeutic agents damage the thymic stroma and impair robust reconstitution. We now present data demonstrating that with increasing age reconstitution becomes less robust. Thus in mice older than 16 months unlike in those younger than twelve months, donor derived T lymphocytes can be identified, but the absolute cellularity of the thymus does not increase after transplant. In addition, we demonstrate that there are agent specific defects in the stromal compartments of treated aged mice. We have proceeded to identify a subset of agents (including split dose irradiation) that impair reconstitution in aged recipients but do not do so in the young. Thus while reconstitution of the thymus of young mice subjected to hyperfractionated total body irradiation declines 28 +/− 3% that of old mice treated in the same manner declines 91 +/− 6%. This last finding has enabled us to identify specific “at risk” stromal populations that normally appear to support the DN2 to DN3 transition in T lymphopoiesis. In a series of experiments designed to ask whether these at risk stromal populations can be protected from injury we identify agent specific differences in mechanisms of injury. It is anticipated that results from these investigations will augment our understanding of lympho-stromal interactions crucial to normal intra-thymic T cell development.


Blood ◽  
2007 ◽  
Vol 109 (9) ◽  
pp. 3803-3811 ◽  
Author(s):  
Simona W. Rossi ◽  
Lukas T. Jeker ◽  
Tomoo Ueno ◽  
Sachiyo Kuse ◽  
Marcel P. Keller ◽  
...  

Abstract The systemic administration of keratinocyte growth factor (KGF) enhances T-cell lymphopoiesis in normal mice and mice that received a bone marrow transplant. KGF exerts protection to thymic stromal cells from cytoablative conditioning and graft-versus-host disease–induced injury. However, little is known regarding KGF's molecular and cellular mechanisms of action on thymic stromal cells. Here, we report that KGF induces in vivo a transient expansion of both mature and immature thymic epithelial cells (TECs) and promotes the differentiation of the latter type of cells. The increased TEC numbers return within 2 weeks to normal values and the microenvironment displays a normal architectural organization. Stromal changes initiate an expansion of immature thymocytes and permit regular T-cell development at an increased rate and for an extended period of time. KGF signaling in TECs activates both the p53 and NF-κB pathways and results in the transcription of several target genes necessary for TEC function and T-cell development, including bone morphogenetic protein 2 (BMP2), BMP4, Wnt5b, and Wnt10b. Signaling via the canonical BMP pathway is critical for the KGF effects. Taken together, these data provide new insights into the mechanism(s) of action of exogenous KGF on TEC function and thymopoiesis.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 68-68
Author(s):  
Susan Prockop ◽  
Sotiris Nikolopoulos ◽  
Aaron Myers ◽  
Filipo Giancotti ◽  
Howard T. Petrie ◽  
...  

Abstract Despite recovery of most hematopoietic functions, prolonged defects in generating functional T lymphocytes is a common occurrence after T cell depleted bone marrow transplant. While the mechanisms of these defects have not all been elucidated, contributing factors include age, T cell depletion of the graft, therapy with radiation and cytotoxic agents, and graft versus host disease (GvHD). We have designed an in vivo functional assessment of the ability of thymic stroma to support de novo T lymphocyte development. Mice deficient for the alpha chain of the IL-7 receptor (IL7Rα−/−) support robust thymic reconstitution after transplant of limited numbers of congenic precursors. We demonstrated that this capacity for reconstitution of immunodeficient strains depends on the paucity of specific endogenous precursors (DN3) cells in the IL7Rα−/− thymus and reflects the presence of functionally normal but empty stromal niches in this immunodeficient strain. We have proceeded to demonstrate that a variety of chemotherapeutic agents as well as aging, impair the ability of IL7Rα−/− thymic stroma to support de novo T cell development. Some agents allow donor chimerism in the thymus, but not rescue of the hypocellularity (eg cyclophosphamide) while others do not affect reconstitution (eg fludarabine). Multi-agent regimens have been administered and in some instances demonstrate an additive detrimental impact on thymic reconstitution. For several agents, damage has been localized to specific stromal niches by isolating changes in lymphoid subsets and stromal keratin expression. Decreased availability of the stromal niche for DN3 progenitors is associated with a decreased frequency of DN3s and an absolute block in recipient IL7Rα−/− T cell development. In addition, RNA from treated and untreated thymic stromal cells has been used to evaluate the gene expression pattern in thymic stroma of IL7Rα−/− mice treated with cytotoxic agents. In one example to be presented we find decreased thymic reconstitution in mice treated with Busulfan with sustained changes in stromal elements. These findings are consistent with sustained damage to thymic stromal cells. Among other changes, busulfan leads to decreased expression of laminin 5 by cortical thymic epithelial cells. The integrin heterodimerα6β4 is a binding partner for laminin 5 and is expressed uniformly by DN2 thymocytes. The significance of laminin 5/α6β4 signaling during T cell development was assessed using mice with a targeted mutation in the integrin β4 signaling domain. In these experiments mutant fetal liver was used to create hematopoietic chimeras and evaluate T cell development. Our studies provide insight into the nature of damage to thymic stroma by cytotoxic regimens and an understanding of the effect of this damage on subsequent immune reconstitution.


Author(s):  
Alexandra Y. Kreins ◽  
Stefano Maio ◽  
Fatima Dhalla

AbstractAs the primary site for T cell development, the thymus is responsible for the production and selection of a functional, yet self-tolerant T cell repertoire. This critically depends on thymic stromal cells, derived from the pharyngeal apparatus during embryogenesis. Thymic epithelial cells, mesenchymal and vascular elements together form the unique and highly specialised microenvironment required to support all aspects of thymopoiesis and T cell central tolerance induction. Although rare, inborn errors of thymic stromal cells constitute a clinically important group of conditions because their immunological consequences, which include autoimmune disease and T cell immunodeficiency, can be life-threatening if unrecognised and untreated. In this review, we describe the molecular and environmental aetiologies of the thymic stromal cell defects known to cause disease in humans, placing particular emphasis on those with a propensity to cause thymic hypoplasia or aplasia and consequently severe congenital immunodeficiency. We discuss the principles underpinning their diagnosis and management, including the use of novel tools to aid in their identification and strategies for curative treatment, principally transplantation of allogeneic thymus tissue.


Immunity ◽  
2002 ◽  
Vol 16 (2) ◽  
pp. 285-296 ◽  
Author(s):  
Michele K Anderson ◽  
Angela H Weiss ◽  
Gabriela Hernandez-Hoyos ◽  
Christopher J Dionne ◽  
Ellen V Rothenberg

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3318-3318
Author(s):  
Nahed El Kassar ◽  
Baishakhi Choudhury ◽  
Francis Flomerfelt ◽  
Philip J. Lucas ◽  
Veena Kapoor ◽  
...  

Abstract IL-7 is a non-redundant cytokine in T cell development. We studied the role of IL-7 in early T-cell development using a model of transgenic (Tg) mice with the murine IL-7 gene under control of the lck proximal promoter. At high IL-7 over-expression (x39 fold increase at day 1 in total thymic tissue), we observed a disruption of TCRαβ development along with increased B cell development in the thymus (7- to 13-fold increase) (El Kassar, Blood, 2004). In order to further explore abnormal T and B cell thymic development in these mice, we first confirmed that they both arise in parallel and were non-cell autonomous, by in vivo injection of neutralizing anti-IL-7 MAb and mixed bone marrow chimera experiments. Using a six color flow cytometry analysis, we found a dramatic decrease of the early thymocyte progenitors (ETPs, lin−CD44+CD25−c-kithiIL-7R−/lo) in the adult Tg mice (x4.7 fold decrease). Lin−CD44+CD25−c-kit+ thymocytes were sorted and cultured on OP9 and OP9 delta-like1 (OP9-DL1) stromal cells (kindly provided by Pr Zuniga Pflucker). At day 14, we observed an important decrease of T cell development (54% vs. 1% of DP cells) and an increase of NK cells (x5 fold increase) in the Tg-derived DN1 cell culture. DN2 (Lin−CD44+CD25−c-kit+) Tg thymocytes showed the same, but less dramatic abnormalities. While DN1 progenitors developed effectively into B220+CD19+ cells on OP9 stromal cells, no B cell development was observed on OP-DL stromal cells from DN1-Tg derived progenitors or by addition of increasingly high doses of IL-7 (x10, x40, x160) to normal B6-derived DN1 progenitors. Instead, a block of T-cell development was observed with increased IL-7. We hypothesized a down regulation of Notch signaling by IL-7 over-expression and analyzed by FACS Notch expression in the DN thymocytes. By staining the intra-cellular part of Notch cleaved after Notch 1/Notch ligand activation, Tg-derived DN2 cells showed decreased Notch signaling. More importantly, HES expression was decreased in the DN2, DN3 and DN4 fractions by semi-quantitative PCR. Sorted Pro/Pre B cells from Tg thymi showed TCR Dβ1-Jβ1 rearrangement indicating their T specific origin, in opposition to Pro/Pre B cells sorted from the bone marrow of the same mice. We suggest that more than one immature progenitor seeds the thymus from the bone marrow. While ETPs had T and NK proliferative capacity, another thymic progenitor with B potential may be responsible for thymic B cell development in normal and IL-7 Tg mice. Finally, IL-7 over-expression may induce a decreased Notch signaling in thymic progenitors, inducing a switch of T vs. B lineage development.


2011 ◽  
Vol 186 (8) ◽  
pp. 4751-4761 ◽  
Author(s):  
Lynda A. O’Sullivan ◽  
Suzita M. Noor ◽  
Monique C. Trengove ◽  
Rowena S. Lewis ◽  
Clifford Liongue ◽  
...  

Blood ◽  
2005 ◽  
Vol 106 (1) ◽  
pp. 193-200 ◽  
Author(s):  
Rafik Terra ◽  
Isabelle Louis ◽  
Richard Le Blanc ◽  
Sophie Ouellet ◽  
Juan Carlos Zúñiga-Pflücker ◽  
...  

In the thymus, 2 types of Lin–Sca-1+ (lineage-negative stem cell antigen-1–positive) progenitors can generate T-lineage cells: c-Kithi interleukin-7 receptor α–negative (c-KithiIL-7Rα–) and c-KitloIL-7Rα+. While c-KithiIL-7Rα– progenitors are absent, c-KitloIL-7Rα+ progenitors are abundant in the lymph nodes (LNs). c-KitloIL-7Rα+ progenitors undergo abortive T-cell commitment in the LNs and become arrested in the G1 phase of the cell cycle because they fail both to up-regulate c-myb, c-myc, and cyclin D2 and to repress junB, p16INK4a, and p21Cip1/WAF. As a result, development of LN c-KitloIL-7Rα+ progenitors is blocked at an intermediate CD44+CD25lo development stage in vivo, and LN-derived progenitors fail to generate mature T cells when cultured with OP9-DL1 stromal cells. LN stroma can provide key signals for T-cell development including IL-7, Kit ligand, and Delta-like–1 but lacks Wnt4 and Wnt7b transcripts. LN c-KitloIL-7Rα+ progenitors are able to generate mature T cells when cultured with stromal cells producing wingless-related MMTV integration site 4 (Wnt4) or upon in vivo exposure to oncostatin M whose signaling pathway intersects with Wnt. Thus, supplying Wnt signals to c-KitloIL-7Rα+ progenitors may be sufficient to transform the LN into a primary T-lymphoid organ. These data provide unique insights into the essence of a primary T-lymphoid organ and into how a cryptic extrathymic T-cell development pathway can be amplified.


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