scholarly journals Current and Future Therapeutic Approaches for Thymic Stromal Cell Defects

2021 ◽  
Vol 12 ◽  
Author(s):  
Alexandra Y. Kreins ◽  
Paola Bonfanti ◽  
E. Graham Davies

Inborn errors of thymic stromal cell development and function lead to impaired T-cell development resulting in a susceptibility to opportunistic infections and autoimmunity. In their most severe form, congenital athymia, these disorders are life-threatening if left untreated. Athymia is rare and is typically associated with complete DiGeorge syndrome, which has multiple genetic and environmental etiologies. It is also found in rare cases of T-cell lymphopenia due to Nude SCID and Otofaciocervical Syndrome type 2, or in the context of genetically undefined defects. This group of disorders cannot be corrected by hematopoietic stem cell transplantation, but upon timely recognition as thymic defects, can successfully be treated by thymus transplantation using cultured postnatal thymic tissue with the generation of naïve T-cells showing a diverse repertoire. Mortality after this treatment usually occurs before immune reconstitution and is mainly associated with infections most often acquired pre-transplantation. In this review, we will discuss the current approaches to the diagnosis and management of thymic stromal cell defects, in particular those resulting in athymia. We will discuss the impact of the expanding implementation of newborn screening for T-cell lymphopenia, in combination with next generation sequencing, as well as the role of novel diagnostic tools distinguishing between hematopoietic and thymic stromal cell defects in facilitating the early consideration for thymus transplantation of an increasing number of patients and disorders. Immune reconstitution after the current treatment is usually incomplete with relatively common inflammatory and autoimmune complications, emphasizing the importance for improving strategies for thymus replacement therapy by optimizing the current use of postnatal thymus tissue and developing new approaches using engineered thymus tissue.

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.


Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 43-44
Author(s):  
Amandine Pradier ◽  
Adrien Petitpas ◽  
Anne-Claire Mamez ◽  
Federica Giannotti ◽  
Sarah Morin ◽  
...  

Introduction Allogeneic hematopoietic stem cell transplantation (HSCT) is a well-established therapeutic modality for a variety of hematological malignancies and congenital disorders. One of the major complications of the procedure is graft-versus-host-disease (GVHD) initiated by T cells co-administered with the graft. Removal of donor T cells from the graft is a widely employed and effective strategy to prevent GVHD, although its impact on post-transplant immune reconstitution might significantly affect anti-tumor and anti-infectious responses. Several approaches of T cell depletion (TCD) exist, including in vivo depletion using anti-thymocyte globulin (ATG) and/or post-transplant cyclophosphamide (PTCy) as well as in vitro manipulation of the graft. In this work, we analyzed the impact of different T cell depletion strategies on immune reconstitution after allogeneic HSCT. Methods We retrospectively analysed data from 168 patients transplanted between 2015 and 2019 at Geneva University Hospitals. In our center, several methods for TCD are being used, alone or in combination: 1) In vivo T cell depletion using ATG (ATG-Thymoglobulin 7.5 mg/kg or ATG-Fresenius 25 mg/kg); 2) in vitro partial T cell depletion (pTCD) of the graft obtained through in vitro incubation with alemtuzumab (Campath [Genzyme Corporation, Cambridge, MA]), washed before infusion and administered at day 0, followed on day +1 by an add-back of unmanipulated grafts containing about 100 × 106/kg donor T cells. The procedure is followed by donor lymphocyte infusions at incremental doses starting with 1 × 106 CD3/kg at 3 months to all patients who had received pTCD grafts with RIC in the absence of GVHD; 3) post-transplant cyclophosphamide (PTCy; 50 mg/kg) on days 3 and 4 post-HSCT. Absolute counts of CD3, CD4, CD8, CD19 and NK cells measured by flow cytometry during the first year after allogeneic HSCT were analyzed. Measures obtained from patients with mixed donor chimerism or after therapeutic DLI were excluded from the analysis. Cell numbers during time were compared using mixed-effects linear models depending on the TCD. Multivariable analysis was performed taking into account the impact of clinical factors differing between patients groups (patient's age, donor type and conditioning). Results ATG was administered to 77 (46%) patients, 15 (9%) patients received a pTCD graft and 26 (15%) patients received a combination of both ATG and pTCD graft. 24 (14%) patients were treated with PTCy and 26 (15%) patients received a T replete graft. 60% of patients had a reduced intensity conditioning (RIC). 48 (29%) patients received grafts from a sibling identical donor, 94 (56%) from a matched unrelated donor, 13 (8%) from mismatched unrelated donor and 13 (8%) received haploidentical grafts. TCD protocols had no significant impact on CD3 or CD8 T cell reconstitution during the first year post-HSCT (Figure 1). Conversely, CD4 T cells recovery was affected by the ATG/pTCD combination (coefficient ± SE: -67±28, p=0.019) when compared to the T cell replete group (Figure 1). Analysis of data censored for acute or chronic GVHD requiring treatment or relapse revealed a delay of CD4 T cell reconstitution in the ATG and/or pTCD treated groups on (ATG:-79±27, p=0.004; pTCD:-100±43, p=0.022; ATG/pTCD:-110±33, p<0.001). Interestingly, pTCD alone or in combination with ATG resulted in a better reconstitution of NK cells compared to T replete group (pTCD: 152±45, p<0.001; ATG/pTCD: 94±36, p=0.009; Figure 1). A similar effect of pTCD was also observed for B cells (pTCD: 170±48, p<.001; ATG/pTCD: 127±38, p<.001). The effect of pTCD on NK was confirmed when data were censored for GVHD and relapse (pTCD: 132±60, p=0.028; ATG/pTCD: 106±47, p=0.023) while only ATG/pTCD retained a significant impact on B cells (102±49, p=0.037). The use of PTCy did not affect T, NK or B cell reconstitution when compared to the T cell replete group. Conclusion Our results indicate that all TCD protocols with the only exception of PTCy are associated with a delayed recovery of CD4 T cells whereas pTCD of the graft, alone or in combination with ATG, significantly improves NK and B cell reconstitution. Figure 1 Disclosures No relevant conflicts of interest to declare.


Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2244-2244
Author(s):  
Gerald J. Spangrude ◽  
Birgitta Johnson ◽  
Scott Cho ◽  
Xiaosong Huang ◽  
L. Jeanne Pierce

Abstract The ability to study lymphocyte differentiation in culture has been greatly advanced by the availability of the OP9 bone marrow stromal cell line, which was derived from an op/op mouse and thus lacks M-CSF. As a result, the normal default myeloid differentiation from bone marrow-derived stem and progenitor cells does not occur, and lymphocyte differentiation is favored. Introduction of the Notch ligand Delta-like 1 into OP9 cells results in promotion of T cell development and parallel suppression of B cell development. While the OP9-DL1 model of T cell development works quite well when fetal liver-derived progenitors are cultured, the success of T cell development from adult bone marrow-derived progenitors has been more difficult to reproduce. We have undertaken a systematic analysis of variables that can prevent efficient T cell development in OP9-DL1 cultures, and have found that one limiting factor that impacts the efficiency of differentiation of both T and B cell lineages is the accumulation of ammonium ions as a result of the spontaneous decomposition of l-glutamine. L-glutamine, which is present at 2 to 4 mM in standard tissue culture media, is unstable and will spontaneously degrade to form ammonium ions and pyroglutamic acid at a rate of 1%/day at 4°C and at a 10-fold higher rate at 37°C. To evaluate the effects of the two major products of l-glutamine decomposition on lymphoid differentiation, we added each product to differentiation cultures at 3 mM in the presence of a stable source of l-glutamine (l-alanyl-l-glutamine). Cultures were established in 1 ml containing 4×104 stromal cells (OP9 for B cell differentiation, OP9-DL1 for T cell differentiation), 1×103 bone marrow-derived lymphoid progenitors enriched by phenotype (c-kit+LinnegSca-1+Thy-1.1neg), and 5 ng/ml Flt3L plus 5 ng/ml IL-7. Every 3 to 4 days, cultures were harvested and passaged onto fresh stromal cell monolayers; lymphoid cells were counted and evaluated for surface antigen expression at each passage. While addition of pyroglutamic acid had no inhibitory effect on lymphocyte growth or differentiation, addition of ammonium chloride slowed growth and prevented differentiation of both T and B lymphocytes. Growth of the stromal cell monolayers was not affected by ammonium chloride at the concentrations utilized in these studies. We conclude that freshly-prepared culture medium, preferably containing a stabilized form of l-glutamine, is a critical aspect contributing to the success of lymphocyte differentiation cultures established from adult bone marrow cells. We also found that decreasing IL-7 concentrations to 1 ng/ml resulted in more rapid differentiation of T cells and a more balanced representation of CD4 and CD8 single positive cells. Our studies help define optimal conditions for differentiation of bone marrow-derived lymphoid progenitor cells into T and B lineages in vitro, and provide evidence that hematopoietic differentiation displays variable degrees of sensitivity to ammonium ions derived from decomposition of l-glutamine. These results will help define optimal conditions for expansion and differentiation of hematopoietic stem and progenitor cells in vitro.


Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 184-184
Author(s):  
Takeshi Isoda ◽  
Masatoshi Takagi ◽  
Jinhua Piao ◽  
Shun Nakagama ◽  
Masaki Sato ◽  
...  

Abstract Abstract 184FN2 Ataxia Telangiectagia (AT) is an autosomal recessive immunodeficiency, caused by mutation of ataxia telangiectagia mutated gene (ATM). ATM plays a crucial role for responding to DNA damages by extrinsic and intrinsic factors, and is a master regulator for maintaining DNA integrity. VDJ recombination and class switch recombination during lymphocyte maturation are the steps of intrinsic DNA damage response where ATM stabilizes DNA ends during recombination. ATM deficiency (ATM−/−) is known to predispose to T-cell lymphopenia and T-lineage lymphoma development. ATM−/− mouse has been shown to have a failure of T-cell development at the stage from double positive (DP) to single positive (SP) differentiation, which is due to a failure of T-cell receptor a (TCRa) recombination. Thymic lymphomas in ATM−/− mice have recently been shown to have a chromosome 14 translocation involving TCRd locus, suggesting that the first event for translocation arises during TCRd locus recombination at double negative (DN) stage. However, phenotypic features of T-cell development at DN phase and the timing of chromosome 14 translocation formation in ATM−/− are not fully elucidated. Here we demonstrate that T cells of ATM−/− mice show a failure at the transition from DN3a to DN3b at b and gd-selection checkpoints due to multiple TCR recombination failure in-vivo. Consistent with in-vivo developmental profiles of ATM−/− mice thymocytes, long term hematopoietic stem cells (LTR-HSCs) of ATM−/− mice cultured with OP9-DLL1 show a delay at b-selection checkpoint in chronological order. In this culture system, failures in gd-T-cell development are also observed in ATM−/− LTR-HSCs. Involvement of thymic stromas in the failure of this transition was ruled out by bone-marrow transplantation (BMT) of ATM−/− donor to WT recipient mice, where thymocytes reconstitution showed the same transition failure at b-selection checkpoint. Thymocytes in RAG2−/− mice are arrested at DN3 stage by a failure of cleavage of TCR genes, but the arrested thymocytes are known to progress to DP phase by anti-CD3e antibody stimulation. This experiment enables to analyze pre-TCR dependent differentiation signal machinery. Then anti-CD3e antibody was injected into RAG2−/−ATM−/− mouse and DN3 cells were shown to be led to DP phase, indicating that ATM itself is not involved in the differentiation program during DN to DP phase. These results suggested loss of ATM attenuates T cell differentiation at DN3a to DN3b transition due to inefficient TCRg, d and b locus recombination. Thus differentiation failure from DN3a to DN3b in ATM deficiency is presumably the primary cause of T cell lymphopenia at the stage prior to positive-selection. We next investigated when of the differentiation stages chromosome 14 translocation involving TCRa/d locus monitored. When the LTR-HSCs is cultured on the OP9-DLL1 cells with high-dose cytokine including 10 ng/ml of Flt3-L, IL-7 and SCF, differentiation of LTR-HSCs to T cells halt at DN2-3a phase before b-selection. Then, by reducing the Flt3-L and IL7 to 5 ng/ml and 1 ng/ml, respectively, the differentiation arrest is released and Tcell differentiation progresses from DN3a to DN3b. No detectable chromosome break at TCRad locus was observed at DN2-3a in wild type, while 5% of ATM−/− cells carried TCRad break, associated with chromosome 14 translocation in approximately 0.8 % of DN2-3a cells. After progression to DN3b-4 phase, TCRad locus break was still observed in AT cells at the frequency of 1%, and chromosome 14 translocations involving TCRad locus was observed in 12% of ATM−/− cells, which was in contrast to none in wild type cell. Mono- or bi-allelic TCRa/d breaks, chromosome 14 dicentric, and t (12:14) were also observed in minor population of ATM−/− cells. These results suggest that critical point for generation of chromosome 14 translocations involving TCRa/d locus lies at DN2-3a to 3b stages corresponding during b and gd selection checkpoint in ATM deficient thymocytes. Our findings revealed that developmental failure of T-cells in AT arises during b and gd–selection checkpoint, which leads to the breaks of TCRa/d locus and subsequent chromosome 14 translocation formation. Thus we propose T-lymphopenia and predisposition to T cell leukemia/lymphoma are tightly connected in ATM deficient condition. Disclosures: No relevant conflicts of interest to declare.


1998 ◽  
Vol 5 (4) ◽  
pp. 287-302 ◽  
Author(s):  
Tannishtha Reya ◽  
Hamid Bassiri ◽  
Renée Biancaniello ◽  
Simon R. Carding

The role that interleukin-2 (IL-2) plays in T-cell development is not known. To address this issue, we have investigated the nature of the abnormal thymic development and autoimmune disorders that occurs in IL-2-deficient (IL-2–/–) mice. After 4 to 5 weeks of birth, IL-2–/–mice progressively develop a thymic disorder resulting in the disruption of thymocyte maturation. This disorder is characterized by a dramatic reduction in cellularity, the selective loss of immature CD4-8-(double negative; DN) and CD4+8+(double positive; DP) thymocytes and defects in the thymic stromal-cell compartment. Immunohistochemical staining of sections of thymuses from specific pathogen-free and germ-free IL-2–/–mice of various ages showed a progressive ,loss of cortical epithelial cells, MHC class II-expressing cells, monocytes, and macrophages. Reduced numbers of macrophages were apparent as early as week after birth. Since IL-2–/–thymocyte progenitor populations could mature normally on transfer into a normal thymus, the thymic defect in IL-2–/–mice appears to be due to abnormalities among thymic stromal cells. These results underscore the role of IL-2 in maintaining functional microenvironments that are necessary to support thymocyte growth, development, and selection.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ashton C. Trotman-Grant ◽  
Mahmood Mohtashami ◽  
Joshua De Sousa Casal ◽  
Elisa C. Martinez ◽  
Dylan Lee ◽  
...  

AbstractT cells are pivotal effectors of the immune system and can be harnessed as therapeutics for regenerative medicine and cancer immunotherapy. An unmet challenge in the field is the development of a clinically relevant system that is readily scalable to generate large numbers of T-lineage cells from hematopoietic stem/progenitor cells (HSPCs). Here, we report a stromal cell-free, microbead-based approach that supports the efficient in vitro development of both human progenitor T (proT) cells and T-lineage cells from CD34+cells sourced from cord blood, GCSF-mobilized peripheral blood, and pluripotent stem cells (PSCs). DL4-μbeads, along with lymphopoietic cytokines, induce an ordered sequence of differentiation from CD34+ cells to CD34+CD7+CD5+ proT cells to CD3+αβ T cells. Single-cell RNA sequencing of human PSC-derived proT cells reveals a transcriptional profile similar to the earliest thymocytes found in the embryonic and fetal thymus. Furthermore, the adoptive transfer of CD34+CD7+ proT cells into immunodeficient mice demonstrates efficient thymic engraftment and functional maturation of peripheral T cells. DL4-μbeads provide a simple and robust platform to both study human T cell development and facilitate the development of engineered T cell therapies from renewable sources.


2020 ◽  
Vol 88 ◽  
pp. S51
Author(s):  
Victoria Sun ◽  
Amelie Montel-Hagen ◽  
David Casero ◽  
Steven Tsai ◽  
Alexandre Zampieri ◽  
...  

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi104-vi104
Author(s):  
Bayli DiVita Dean ◽  
Tyler Wildes ◽  
Joseph Dean ◽  
David Shin ◽  
Connor Francis ◽  
...  

Abstract INTRODUCTION Bone marrow-derived hematopoietic stem and progenitor cells (HSPCs) give rise to the cellular components of the immune system. Unfortunately, immune reconstitution from HSPCs are negatively impacted by solid cancers, including high-grade gliomas. For example, an expansion of myeloid progenitor cells has been previously described across several cancers that originate outside the CNS. A similar expansion of MDSCs coupled with diminished T cell function has also been described in the peripheral blood of patients with newly-diagnosed GBM. Alterations in both lymphoid and myeloid compartments due to CNS malignancy led us to determine how intracranial gliomas impact HSPCs in both their capacity to reconstitute the immune compartment and in their cell fate determination. This is important to better understand the impact of gliomas on immunity and how we can leverage these findings to better develop cellular immunotherapeutics. METHODS HSPCs were isolated from bone marrow of C57BL/6 mice with orthotopic KR158B glioma, or age-matched naïve mice. Experiments were conducted to compare relative changes in: gene expression (RNA-sequencing), precursor frequencies, cell fate determination, and cellular function of cells derived from HSPCs of glioma-bearing mice. RESULTS RNA-sequencing revealed 700+ genes whose expression was significantly up- or downregulated in HSPCs from glioma-bearing mice, particularly those involved with stemness and metabolic activity. Importantly, HSPCs from glioma-bearing mice expressed upregulation of genes involved in myelopoiesis relative to naïve mice. This was coupled with an expansion of granulocyte macrophage precursors (GMPs), the progenitors to gMDSCs. Next, differentiation assays revealed that HSPCs from glioma-bearing mice had higher propensity of differentiating into MDSC under homeostatic conditions relative to controls both in vitro and in vivo. Furthermore, mice bearing intracranial gliomas possess an expansion of MDSCs which are more suppressive on T cell proliferation and hinders T cell-mediated tumor cell killing relative to MDSCs derived from naïve control mice.


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