Adult thymuses lacking either ephrin type B receptor 2 (EphB2) or EphB3, or expressing a truncate... more Adult thymuses lacking either ephrin type B receptor 2 (EphB2) or EphB3, or expressing a truncated form of EphB2, the forward signal-deficient EphB2LacZ, have low numbers of early thymic progenitors (ETPs) and are colonized in vivo by reduced numbers of injected bone marrow (BM) lineage-negative (Lin(-)) cells. Hematopoietic progenitors from these EphB mutants showed decreased capacities to colonize wild type (WT) thymuses compared with WT precursors, with EphB2(-/-) cells exhibiting the greatest reduction. WT BM Lin(-) cells also showed decreased colonizing capacity into mutant thymuses. The reduction was also more severe in EphB2(-/-) host thymuses, with a less severe phenotype in the EphB2LacZ thymus. These results suggest a major function for forward signaling through EphB2 and, to a lesser extent, EphB3, in either colonizing progenitor cells or thymic stromal cells, for in vivo adult thymus recruitment. Furthermore, the altered expression of the molecules involved in thymic col...
In the translational process of developing innovative therapies for DMD (Duchenne muscular dystro... more In the translational process of developing innovative therapies for DMD (Duchenne muscular dystrophy), the last preclinical validation step is often carried out in the most relevant animal model of this human disease, namely the GRMD (Golden Retriever muscular dystrophy) dog. The disease in GRMD dogs mimics human DMD in many aspects, including the inter-individual heterogeneity. This last point can be seen as a drawback for an animal model but is inherently related to the disease in GRMD dogs closely resembling that of individuals with DMD. In order to improve the management of this inter-individual heterogeneity, we have screened a combination of biomarkers in sixty-one 2-month-old GRMD dogs at the onset of the disease and a posteriori we addressed their predictive value on the severity of the disease. Three non-invasive biomarkers obtained at early stages of the disease were found to be highly predictive for the loss of ambulation before 6 months of age. An elevation in the number...
Thymocytes from mice with experimental Trypanosoma cruzi infection respond poorly to Con-A stimul... more Thymocytes from mice with experimental Trypanosoma cruzi infection respond poorly to Con-A stimulation. However, the proliferative capacity of these cells is not impaired, as demonstrated by the fact that at high doses, exogenous rIL-2 restores thymidine uptake. This finding could be explained either by insufficient IL-2 production or by the appearance of inhibitory factors during T. cruzi infection. This paper shows that in response to Con A, IL-2 production is decreased in the model. Furthermore, the whole profile of cytokine production is modified, with a striking increase in IL-10, IFN-gamma, IL-4, IL-5 and IL-6 production. The results indicate that IL-10 plus IFN-gamma are responsible for the decrease in the Con A-induced proliferation since a normal proliferative response as well as normal IL-2 production can be restored if both cytokines are neutralized by adding their monoclonal antibodies (MoAbs). Evidence is provided also for an enhanced non-specific cytotoxicity of thymic...
The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society, 1988
A major component of the thymic microenvironment is a network of thymic epithelial cells (TEC) wh... more A major component of the thymic microenvironment is a network of thymic epithelial cells (TEC) which are able to express class II major histocompatibility complex products and to secrete thymic hormones. In the present investigation, we used a panel of anti-cytokeratin (CK) antibodies to establish distinct cytokeratin-defined TEC subsets. Four subpopulations were identified. One, in the cortex, is defined by anti-CK8 and anti-CK18 monoclonal antibodies (MAb). The other three subsets are medullary, two minor ones respectively reactive with anti-CK19 and KL1 monoclonal antibodies (the latter being specific for CK3 and 10), and a major one characterized by negative reaction with the above-mentioned MAb but strongly positive after labeling with a polyclonal (and polyspecific) anti-keratin immunoserum. Ontogenetic studies revealed that the CK8+/18+ TEC subset is the first to be detected in fetal life. Moreover, the numbers of CK3/10+ cells and CK19+ cells decrease in aging normal mice, a...
The pathogenesis of chronic chagasic cardiomyopathy associated with Chagas disease is still contr... more The pathogenesis of chronic chagasic cardiomyopathy associated with Chagas disease is still controversial, although evidence indicates a T cell-dependent autoimmune process. Using a mouse model for chronic Chagas disease, we previously evidenced that hearts grafted within the ears of Trypanosoma cruzi infected syngeneic recipients were rejected through a CD4+ T cell-dependent mechanism. Moreover, we showed that such a process was dependent on laminin-mediated interactions, since it could be abrogated by anti-laminin or anti-laminin receptor antibodies. In this review the same passive cell transfer model is considered for discussion: the participation of the laminin alteration in the composition of the inflammatory infiltrate formed in response to the antimyocardial autoreactive CD4+ T cells, as well as the presence of laminin-binding cytokines. Finally we suggest the existence of a relationship between the inflammatory infiltrate, the laminin contents and deposition of pro-inflammatory laminin-binding cytokines, which may act in concert during the generation of Chagas disease-related cardiomyopathy.
Epidermal changes from 32 cutaneous and 3 mucosal American cutaneous leishmaniasis (ACL) active l... more Epidermal changes from 32 cutaneous and 3 mucosal American cutaneous leishmaniasis (ACL) active lesions were studied for HLA-DR, -DQ and -DP expression, Langerhans cells and lymphocyte infiltration. In addition to a DR and DQ positivity at the surface of the cells of the inflammatory infiltrate, a strong reaction for DR antigens was detected on keratinocytes. Hyperplasia of Langerhans cells was present in all cutaneous lesions and epidermis was infiltrated by T lymphocytes. When healed lesions of 14 of these subjects were re-biopsied 1 to 12 months after the end of pentavalent antimonial therapy, MHC class II antigens could no longer be seen on keratinocytes. Our data represent evidence for the reversibility of the abnormal HLA-DR expression by keratinocytes in ACL after Glucantime therapy or spontaneous scar formation, demonstrating that this expression is restricted to the period of active lesions. The present findings can be regarded as an indirect evidence that keratinocytes may be involved in the immunopathology of ACL.
A saline extract (SE) derived from living adult Schistosoma mansoni confers high levels of resist... more A saline extract (SE) derived from living adult Schistosoma mansoni confers high levels of resistance to challenge infection in mice and rabbits. We have carried out a number of experiments to analyse the composition of SE and to define the proteins that are rapidly released from the parasite. One of these proteins, with apparent molecular mass of 62 kDa, is recognized by polyclonal and monoclonal antibodies raised against high molecular mass cytokeratins from human epidermal cells. Immunocytochemical studies revealed a tegumental staining using the anti-cytokeratin antibody. Moreover, sera from schistosomiasis patients, as well as those from animals immunized with SE, were able to recognize this 62 kDa polypeptide as shown by immunoblot assays. These results suggest the existence of cytokeratin-containing filaments in the schistosome.
The protozoan parasite Trypanosoma cruzi is able to target the thymus and induce alterations of t... more The protozoan parasite Trypanosoma cruzi is able to target the thymus and induce alterations of the thymic microenvironmental and lymphoid compartments. Acute infection results in severe atrophy of the organ and early release of immature thymocytes into the periphery. To date, the pathophysiological effects of thymic changes promoted by parasite-inducing premature release of thymocytes to the periphery has remained elusive. Herein, we show that sphingosine-1-phosphate (S1P), a potent mediator of T cell chemotaxis, plays a role in the exit of immature double-negative thymocytes in experimental Chagas disease. In thymuses from T. cruzi-infected mice we detected reduced transcription of the S1P kinase 1 and 2 genes related to S1P biosynthesis, together with increased transcription of the SGPL1 sphingosine-1-lyase gene, whose product inactivates S1P. These changes were associated with reduced intrathymic levels of S1P kinase activity. Interestingly, double-negative thymocytes from infec...
Proceedings of The National Academy of Sciences, 1996
Molecular cloning of components of protective antigenic preparations has suggested that related p... more Molecular cloning of components of protective antigenic preparations has suggested that related parasite fatty acid-binding proteins could form the basis of the protective immune crossreactivity between the parasitic trematode worms Fasciola hepatica and Schistosoma mansoni. Molecular models of the two parasite proteins showed that both molecules adopt the same basic three-dimensional structure, consisting of a barrel-shaped molecule formed by 10
Adult thymuses lacking either ephrin type B receptor 2 (EphB2) or EphB3, or expressing a truncate... more Adult thymuses lacking either ephrin type B receptor 2 (EphB2) or EphB3, or expressing a truncated form of EphB2, the forward signal-deficient EphB2LacZ, have low numbers of early thymic progenitors (ETPs) and are colonized in vivo by reduced numbers of injected bone marrow (BM) lineage-negative (Lin(-)) cells. Hematopoietic progenitors from these EphB mutants showed decreased capacities to colonize wild type (WT) thymuses compared with WT precursors, with EphB2(-/-) cells exhibiting the greatest reduction. WT BM Lin(-) cells also showed decreased colonizing capacity into mutant thymuses. The reduction was also more severe in EphB2(-/-) host thymuses, with a less severe phenotype in the EphB2LacZ thymus. These results suggest a major function for forward signaling through EphB2 and, to a lesser extent, EphB3, in either colonizing progenitor cells or thymic stromal cells, for in vivo adult thymus recruitment. Furthermore, the altered expression of the molecules involved in thymic col...
In the translational process of developing innovative therapies for DMD (Duchenne muscular dystro... more In the translational process of developing innovative therapies for DMD (Duchenne muscular dystrophy), the last preclinical validation step is often carried out in the most relevant animal model of this human disease, namely the GRMD (Golden Retriever muscular dystrophy) dog. The disease in GRMD dogs mimics human DMD in many aspects, including the inter-individual heterogeneity. This last point can be seen as a drawback for an animal model but is inherently related to the disease in GRMD dogs closely resembling that of individuals with DMD. In order to improve the management of this inter-individual heterogeneity, we have screened a combination of biomarkers in sixty-one 2-month-old GRMD dogs at the onset of the disease and a posteriori we addressed their predictive value on the severity of the disease. Three non-invasive biomarkers obtained at early stages of the disease were found to be highly predictive for the loss of ambulation before 6 months of age. An elevation in the number...
Thymocytes from mice with experimental Trypanosoma cruzi infection respond poorly to Con-A stimul... more Thymocytes from mice with experimental Trypanosoma cruzi infection respond poorly to Con-A stimulation. However, the proliferative capacity of these cells is not impaired, as demonstrated by the fact that at high doses, exogenous rIL-2 restores thymidine uptake. This finding could be explained either by insufficient IL-2 production or by the appearance of inhibitory factors during T. cruzi infection. This paper shows that in response to Con A, IL-2 production is decreased in the model. Furthermore, the whole profile of cytokine production is modified, with a striking increase in IL-10, IFN-gamma, IL-4, IL-5 and IL-6 production. The results indicate that IL-10 plus IFN-gamma are responsible for the decrease in the Con A-induced proliferation since a normal proliferative response as well as normal IL-2 production can be restored if both cytokines are neutralized by adding their monoclonal antibodies (MoAbs). Evidence is provided also for an enhanced non-specific cytotoxicity of thymic...
The journal of histochemistry and cytochemistry : official journal of the Histochemistry Society, 1988
A major component of the thymic microenvironment is a network of thymic epithelial cells (TEC) wh... more A major component of the thymic microenvironment is a network of thymic epithelial cells (TEC) which are able to express class II major histocompatibility complex products and to secrete thymic hormones. In the present investigation, we used a panel of anti-cytokeratin (CK) antibodies to establish distinct cytokeratin-defined TEC subsets. Four subpopulations were identified. One, in the cortex, is defined by anti-CK8 and anti-CK18 monoclonal antibodies (MAb). The other three subsets are medullary, two minor ones respectively reactive with anti-CK19 and KL1 monoclonal antibodies (the latter being specific for CK3 and 10), and a major one characterized by negative reaction with the above-mentioned MAb but strongly positive after labeling with a polyclonal (and polyspecific) anti-keratin immunoserum. Ontogenetic studies revealed that the CK8+/18+ TEC subset is the first to be detected in fetal life. Moreover, the numbers of CK3/10+ cells and CK19+ cells decrease in aging normal mice, a...
The pathogenesis of chronic chagasic cardiomyopathy associated with Chagas disease is still contr... more The pathogenesis of chronic chagasic cardiomyopathy associated with Chagas disease is still controversial, although evidence indicates a T cell-dependent autoimmune process. Using a mouse model for chronic Chagas disease, we previously evidenced that hearts grafted within the ears of Trypanosoma cruzi infected syngeneic recipients were rejected through a CD4+ T cell-dependent mechanism. Moreover, we showed that such a process was dependent on laminin-mediated interactions, since it could be abrogated by anti-laminin or anti-laminin receptor antibodies. In this review the same passive cell transfer model is considered for discussion: the participation of the laminin alteration in the composition of the inflammatory infiltrate formed in response to the antimyocardial autoreactive CD4+ T cells, as well as the presence of laminin-binding cytokines. Finally we suggest the existence of a relationship between the inflammatory infiltrate, the laminin contents and deposition of pro-inflammatory laminin-binding cytokines, which may act in concert during the generation of Chagas disease-related cardiomyopathy.
Epidermal changes from 32 cutaneous and 3 mucosal American cutaneous leishmaniasis (ACL) active l... more Epidermal changes from 32 cutaneous and 3 mucosal American cutaneous leishmaniasis (ACL) active lesions were studied for HLA-DR, -DQ and -DP expression, Langerhans cells and lymphocyte infiltration. In addition to a DR and DQ positivity at the surface of the cells of the inflammatory infiltrate, a strong reaction for DR antigens was detected on keratinocytes. Hyperplasia of Langerhans cells was present in all cutaneous lesions and epidermis was infiltrated by T lymphocytes. When healed lesions of 14 of these subjects were re-biopsied 1 to 12 months after the end of pentavalent antimonial therapy, MHC class II antigens could no longer be seen on keratinocytes. Our data represent evidence for the reversibility of the abnormal HLA-DR expression by keratinocytes in ACL after Glucantime therapy or spontaneous scar formation, demonstrating that this expression is restricted to the period of active lesions. The present findings can be regarded as an indirect evidence that keratinocytes may be involved in the immunopathology of ACL.
A saline extract (SE) derived from living adult Schistosoma mansoni confers high levels of resist... more A saline extract (SE) derived from living adult Schistosoma mansoni confers high levels of resistance to challenge infection in mice and rabbits. We have carried out a number of experiments to analyse the composition of SE and to define the proteins that are rapidly released from the parasite. One of these proteins, with apparent molecular mass of 62 kDa, is recognized by polyclonal and monoclonal antibodies raised against high molecular mass cytokeratins from human epidermal cells. Immunocytochemical studies revealed a tegumental staining using the anti-cytokeratin antibody. Moreover, sera from schistosomiasis patients, as well as those from animals immunized with SE, were able to recognize this 62 kDa polypeptide as shown by immunoblot assays. These results suggest the existence of cytokeratin-containing filaments in the schistosome.
The protozoan parasite Trypanosoma cruzi is able to target the thymus and induce alterations of t... more The protozoan parasite Trypanosoma cruzi is able to target the thymus and induce alterations of the thymic microenvironmental and lymphoid compartments. Acute infection results in severe atrophy of the organ and early release of immature thymocytes into the periphery. To date, the pathophysiological effects of thymic changes promoted by parasite-inducing premature release of thymocytes to the periphery has remained elusive. Herein, we show that sphingosine-1-phosphate (S1P), a potent mediator of T cell chemotaxis, plays a role in the exit of immature double-negative thymocytes in experimental Chagas disease. In thymuses from T. cruzi-infected mice we detected reduced transcription of the S1P kinase 1 and 2 genes related to S1P biosynthesis, together with increased transcription of the SGPL1 sphingosine-1-lyase gene, whose product inactivates S1P. These changes were associated with reduced intrathymic levels of S1P kinase activity. Interestingly, double-negative thymocytes from infec...
Proceedings of The National Academy of Sciences, 1996
Molecular cloning of components of protective antigenic preparations has suggested that related p... more Molecular cloning of components of protective antigenic preparations has suggested that related parasite fatty acid-binding proteins could form the basis of the protective immune crossreactivity between the parasitic trematode worms Fasciola hepatica and Schistosoma mansoni. Molecular models of the two parasite proteins showed that both molecules adopt the same basic three-dimensional structure, consisting of a barrel-shaped molecule formed by 10
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