scholarly journals Differential Requirement for Mesenchyme in the Proliferation and Maturation of Thymic Epithelial Progenitors

2003 ◽  
Vol 198 (2) ◽  
pp. 325-332 ◽  
Author(s):  
William E. Jenkinson ◽  
Eric J. Jenkinson ◽  
Graham Anderson
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Function ◽  
Mesenchymal Cells ◽  
Thymic Epithelial Cells ◽  
Thymic Epithelial Cell ◽  
Thymus Development ◽  
Cell Pool ◽  
Proliferation And Differentiation ◽  
Essential Prerequisite

Formation of a mature thymic epithelial microenvironment is an essential prerequisite for the generation of a functionally competent T cell pool. It is likely that recently identified thymic epithelial precursors undergo phases of proliferation and differentiation to generate mature cortical and medullary thymic microenvironments. The mechanisms regulating development of immature thymic epithelial cells are unknown. Here we provide evidence that expansion of embryonic thymic epithelium is regulated by the continued presence of mesenchyme. In particular, mesenchymal cells are shown to mediate thymic epithelial cell proliferation through their provision of fibroblast growth factors 7 and 10. In contrast, differentiation of immature thymic epithelial cells, including acquisition of markers of mature cortical and medullary epithelium, occurs in the absence of ongoing mesenchymal support. Collectively, our data define a role for mesenchymal cells in thymus development, and indicate distinct mechanisms regulate proliferation and differentiation of immature thymic epithelial cells. In addition, our findings may aid in studies aimed at developing strategies to enhance thymus reconstitution and functioning in clinical certain contexts where thymic epithelial cell function is perturbed.

A novel form of cellular communication among thymic epithelial cells: intercellular calcium wave propagation

2003 ◽  
Vol 285 (5) ◽  
pp. C1304-C1313 ◽  
Author(s):  
O. K. Nihei ◽  
A. C. Campos de Carvalho ◽  
D. C. Spray ◽  
W. Savino ◽  
L. A. Alves
Keyword(s):  
Wave Propagation ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Gap Junctions ◽  
Thymic Epithelial Cells ◽  
Calcium Wave ◽  
Thymic Epithelial Cell ◽  
Calcium Waves ◽  
Thymic Nurse Cells ◽  
Epithelial Cell Lines

We here describe intercellular calcium waves as a novel form of cellular communication among thymic epithelial cells. We first characterized the mechanical induction of intercellular calcium waves in different thymic epithelial cell preparations: cortical 1-4C18 and medullary 3-10 thymic epithelial cell lines and primary cultures of thymic “nurse” cells. All thymic epithelial preparations responded with intercellular calcium wave propagation after mechanical stimulation. In general, the propagation efficacy of intercellular calcium waves in these cells was high, reaching 80-100% of the cells within a given confocal microscopic field, with a mean velocity of 6-10 μm/s and mean amplitude of 1.4- to 1.7-fold the basal calcium level. As evaluated by heptanol and suramin treatment, our results suggest the participation of both gap junctions and P2 receptors in the propagation of intercellular calcium waves in thymic nurse cells and the more prominent participation of gap junctions in thymic epithelial cell lines. Finally, in cocultures, the transmission of intercellular calcium wave was not observed between the mechanically stimulated thymic epithelial cell and adherent thymocytes, suggesting that intercellular calcium wave propagation is limited to thymic epithelial cells and does not affect the neighboring thymocytes. In conclusion, these data describe for the first time intercellular calcium waves in thymic epithelial cells and the participation of both gap junctions and P2 receptors in their propagation.

Peptide-amidating Enzymes Are Expressed in the Stellate Epithelial Cells of the Thymic Medulla

1998 ◽  
Vol 46 (5) ◽  
pp. 661-668 ◽  
Author(s):  
Alfredo Martínez ◽  
Andrew Farr ◽  
Michele D. Vos ◽  
Frank Cuttitta ◽  
Anthony M. Treston
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Lines ◽  
B Lymphocyte ◽  
Regulatory Peptides ◽  
Convincing Evidence ◽  
Thymic Epithelial Cells ◽  
Thymic Epithelial Cell ◽  
Epithelial Cell Lines ◽  
Amidating Enzymes

C-terminal amidation is a post-translational processing step necessary to convey biological activity to a large number of regulatory peptides. In this study we have demonstrated that the peptidyl-glycine α-amidating monooxygenase enzyme complex (PAM) responsible for this activity is located in the medullary stellate epithelial cells of the thymus and in cultured epithelial cells bearing a medullary phenotype, using Northern blot, immunocytochemistry, in situ hybridization, and enzyme assays. Immunocytochemical localization revealed a granular pattern in the cytoplasm of the stellate cells, which were also positive for cytokeratins and a B-lymphocyte-associated antigen. The presence of PAM activity in medium conditioned by thymic epithelial cell lines suggests that PAM is a secreted product of these cells. Among the four epithelial cell lines examined, there was a direct correlation between PAM activity and content of oxytocin, an amidated peptide. Taken together, these data provide convincing evidence that thymic epithelial cells have the capacity to generate amidated peptides that may influence T-cell differentiation and suggest that the amidating enzymes could play an important role in the regulation of thymic physiology.

scholarly journals Heterogeneity of thymic epithelial cell (TEC) keratins--immunohistochemical and biochemical evidence for a subset of highly differentiated TEC in the mouse.

1985 ◽  
Vol 33 (7) ◽  
pp. 687-694 ◽  
Author(s):  
J F Nicolas ◽  
W Savino ◽  
A Reano ◽  
J Viac ◽  
J Brochier ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
High Molecular Weight ◽  
Thymic Epithelial Cells ◽  
Thymic Epithelial Cell ◽  
Small Subset ◽  
Thymic Epithelium ◽  
Differentiated Cells ◽  
Medullary Epithelial Cells

The mouse thymic epithelial network was studied using three different anti-keratin antibodies. One of these antibodies, KL1, exclusively recognized a small subset of medullary epithelial cells characterized by its content of a high molecular weight keratin (63 kD). Since epithelial differentiation is known to be associated with the acquisition of high molecular weight keratins, KL1-positive cells, which express the Ia antigen and secrete thymulin, may represent a subset of highly differentiated cells among mouse thymic epithelial cells (TEC). These data reflect the heterogeneity of the thymic epithelium and support the concept that distinct TEC subsets might provide the thymus with different microenvironments.

Lymphoid adhesion promotes human thymic epithelial cell survival via NF-(kappa)B activation

2000 ◽  
Vol 113 (1) ◽  
pp. 169-177
Author(s):  
M.T. Scupoli ◽  
E. Fiorini ◽  
P.C. Marchisio ◽  
O. Poffe ◽  
E. Tagliabue ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Survival ◽  
Functional Differentiation ◽  
Binding Activity ◽  
Thymic Epithelial Cells ◽  
Thymic Epithelial Cell ◽  
Nf Kappa B ◽  
Promoting Effect

Inside the thymus, thymic epithelial cells and thymocytes show an interdependent relationship for their functional differentiation and development. As regards possible interdependency for their mutual survival, it is clear that lympho-epithelial adhesion can control the survival of developing thymocytes whereas the effects of lymphoid adhesion on epithelial cell survival have never been described. To address this issue, we performed co-cultures between normal human thymic epithelial cells (TEC) and a mature lymphoid T cell line (H9) or unfractionated thymocytes. TEC were induced to apoptosis by growth factor deprivation and the level of cell death was measured by flow cytometry. TEC stimulated by cell adhesion showed a significant reduced apoptosis when compared to the control and this phenomenon was associated with increased binding activity of NF-(kappa)B, as measured by gel shift analysis. The activation of NF-(kappa)B was necessary to promote survival, since its inhibition by acetyl salicylic acid prevented the promoting effect. The mAb-mediated crosslinking of (alpha)(3)(beta)(1) was considered as a potential inducer of TEC survival, since we have previously demonstrated that the engagement of this integrin was able to induce NF-(kappa)B activation in TEC. The crosslinking of (alpha)(3)(beta)(1), which clustered at the lympho-epithelial contact sites, partially reproduced the promoting activity of cell adhesion. These results highlight that lympho-epithelial adhesion can control the survival of thymic epithelial cells through an intracellular pathway which requires the activation of NF-(kappa)B and is triggered by integrins of the (beta)(1) family.

scholarly journals Measles Virus Infection Induces Terminal Differentiation of Human Thymic Epithelial Cells

1999 ◽  
Vol 73 (3) ◽  
pp. 2212-2221 ◽  
Author(s):  
Hélène Valentin ◽  
Olga Azocar ◽  
Branka Horvat ◽  
Rejane Williems ◽  
Robert Garrone ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Virus Infection ◽  
Measles Virus ◽  
Terminal Differentiation ◽  
Thymic Epithelial Cells ◽  
Thymic Epithelial Cell ◽  
Epithelial Cell Line ◽  
Epithelial Cell Differentiation

ABSTRACT Measles virus infection induces a profound immunosuppression that may lead to serious secondary infections and mortality. In this report, we show that the human cortical thymic epithelial cell line is highly susceptible to measles virus infection in vitro, resulting in infectious viral particle production and syncytium formation. Measles virus inhibits thymic epithelial cell growth and induces an arrest in the G0/G1 phases of the cell cycle. Moreover, we show that measles virus induces a progressive thymic epithelial cell differentiation process: attached measles virus-infected epithelial cells correspond to an intermediate state of differentiation while floating cells, recovered from cell culture supernatants, are fully differentiated. Measles virus-induced thymic epithelial cell differentiation is characterized by morphological and phenotypic changes. Measles virus-infected attached cells present fusiform and stellate shapes followed by a loss of cell-cell contacts and a shift from low- to high-molecular-weight keratin expression. Measles virus infection induces thymic epithelial cell apoptosis in terminally differentiated cells, revealed by the condensation and degradation of DNA in measles virus-infected floating thymic epithelial cells. Because thymic epithelial cells are required for the generation of immunocompetent T lymphocytes, our results suggest that measles virus-induced terminal differentiation of thymic epithelial cells may contribute to immunosuppression, particularly in children, in whom the thymic microenvironment is of critical importance for the development and maturation of a functional immune system.

Protection from thymic epithelial cell injury by keratinocyte growth factor: a new approach to improve thymic and peripheral T-cell reconstitution after bone marrow transplantation

Blood ◽  
2002 ◽  
Vol 99 (12) ◽  
pp. 4592-4600 ◽  
Author(s):  
Dullei Min ◽  
Patricia A. Taylor ◽  
Angela Panoskaltsis-Mortari ◽  
Brile Chung ◽  
Dimitry M. Danilenko ◽  
...  
Keyword(s):  
Immune Deficiency ◽  
Bone Marrow ◽  
Bone Marrow Transplantation ◽  
Growth Factor ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Marrow Transplantation ◽  
Keratinocyte Growth Factor ◽  
Thymic Epithelial Cells ◽  
Thymic Epithelial Cell

Decreased thymopoietic capacity contributes to the severe and clinically significant immune deficiency seen after bone marrow transplantation (BMT). One mechanism for thymopoietic failure is damage to the interleukin 7 (IL-7)–producing thymic epithelial cells (TECs) by irradiation and chemotherapy, which can be partially treated by IL-7 administration. Pretreatment of BMT recipients with keratinocyte growth factor (KGF, or Fgf7), an epithelial cell–specific growth factor, protects mucosal, cutaneous, and pulmonary epithelial cells from cytotoxic therapy-induced damage in experimental murine models. Like other epithelial cells, TECs specifically express KGF receptors. Because KGF specifically protects KGF receptor–bearing epithelial cells and post-BMT immune deficiency is caused by loss of TECs, we hypothesized that KGF pretreatment would improve post-BMT thymic function. To test the hypothesis, BMT recipient mice were given KGF or placebo prior to congenic or allogeneic BMT. Administration of KGF before murine BMT significantly increased the capacity of the thymus to generate donor-derived thymocytes. KGF pretreatment also normalized the proportion of thymic subpopulations, increased the number of naive T cells in the periphery, and improved the response to neoantigen immunization. KGF treatment caused increased production of intrathymic IL-7, and the thymopoietic effects of KGF required an intact IL-7 signaling pathway. These results demonstrate that KGF may have immunomodulatory effects by a unique mechanism of protection of TECs. Furthermore, thymic injury and prolonged posttransplantation immune deficiency in BMT recipients can be prevented by KGF administration.

scholarly journals High efficiency transfection of thymic epithelial cell lines and primary thymic epithelial cells by Nucleofection.

2015 ◽  
Author(s):  
Richard T O'Neil ◽  
Qiaozhi Wei ◽  
Brian G Condie
Keyword(s):  
T Cells ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Lines ◽  
High Efficiency ◽  
Thymic Epithelial Cells ◽  
Thymic Epithelial Cell ◽  
Thymus Tissue ◽  
Primary Mouse ◽  
Epithelial Cell Lines

Thymic epithelial cells (TECs) are required for the development and differentiation of T cells and are sufficient for the positive and negative selection of developing T cells. Although TECs play a critical role in T cell biology, simple, efficient and readily scalable methods for the transfection of TEC lines and primary TECs have not been described. We tested the efficiency of Nucleofection for the transfection of 4 different mouse thymic epithelial cell lines that had been derived from cortical or medullary epithelium. We also tested primary mouse thymic epithelial cells isolated from fetal and postnatal stages. We found that Nucleofection was highly efficient for the transfection of thymic epithelial cells, with transfection efficiencies of 30-70% for the cell lines and 15-35% for primary TECs with low amounts of cell death. Efficient transfection by Nucleofection can be performed with established cortical and medullary thymic epithelial cell lines as well as primary TECs isolated from E15.5 day fetal thymus or postnatal day 3 or 30 thymus tissue. The high efficiency of Nucleofection for TEC transfection will enable the use of TEC lines in high throughput transfection studies and simplifies the transfection of primary TECs for in vitro or in vivo analysis.

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