Increased cardiac workload by closure of the ductus arteriosus leads to hypertrophy and apoptosis rather than to hyperplasia in the late fetal period

It is generally thought that adult mammalian cardiomyocytes compensate for an increased workload by hypertrophy, whereas fetal myocardium grows by cellular proliferation. We analyzed the response of late-fetal rat hearts upon an increased workload imposed by premature constriction of the ductus arteriosus with indomethacin. Initially the fetal heart responds by proliferative growth, as both wet weight and labeling index (bromodeoxyuridine incorporation) of the ventricles increased, whereas neither a change in the fibroblast fraction, ploidy and nucleation in the ventricles is observed. However, this hyperplastic growth is abrogated by a subsequent burst in apoptosis and followed by a hypertrophic response as based on a decrease in DNA and increase in both RNA and protein concentration. This hypertrophic growth was accompanied by a 1.4-fold increase in the volume of the cardiomyocytes. Changes in the molecular phenotype characteristic of pressure-overload hypertrophic growth accompany the process. Thus, the levels of expression of beta-myosin heavy chain and atrial natriuretic factor mRNA increased, of sarcoplasmic/endoplasmic reticulum ATPase (SERCA2) mRNA decreased, and of alpha-myosin heavy chain, phospholamban, and calsequestrin mRNA did not change. In situ hybridization showed that the pattern of mRNA expression changed first in the right ventricular wall and subsequently in the left ventricular free wall as well. It is concluded that pressure-overload imposed on the late-fetal heart induces limited proliferative growth complemented by extensive hypertrophic growth.

Expression analysis of subtractively enriched libraries (EASEL): a widely applicable approach to the identification of differentially expressed genes

A variety of methods for high throughput analysis of differential gene expression has been developed over the past years. We have implemented the EASEL technique that adds flexibility, efficiency and wide-applicability to these methods. The EASEL procedure is unique as it integrates several well established techniques and thereby offers a combination of subtractive hybridization of 3' cDNA ends with macroarrays analysis and Serial Analysis of Gene Expression (SAGE). In addition, once a set of interesting, differentially expressed genes is identified, the material required for follow up studies to test the hypothesis that the gene is truly involved in the process of interest is readily available. In this report, we first present a step-by-step validation of the procedure, since several of the incorporated steps had to be tailored to meet specific requirements and implied drastic modifications of the original methods. Secondly, we applied EASEL to the identification of up-regulated gene products in the outflow tract region of the embryonic rat heart. Here we provide evidence that at least two among the differentially expressed genes detected, follistatin-like protein gene and membrane type 1-metallo proteinase gene, are selectively up-regulated in the outflow tract, suggesting their involvement in the development of this region during embryogenesis.

Type 1- and type 2-like lesional skin-derived Mycobacterium leprae-responsive T cell clones are characterized by coexpression of IFN-gamma/TNF-alpha and IL-4/IL-5/IL-13, respectively

In an earlier study, we generated a large number of Mycobacterium leprae-responsive and M. leprae-nonresponsive T cell clones (TCC) from the lesional skin of immunologic unstable borderline leprosy patients. In that study, we divided TCC into type 1- and type 2-like on the basis of their IFN-gamma and IL-4 expression. To explore whether other cytokines are coproduced along with IFN-gamma and IL-4, we investigated the secretion of a panel of other cytokines (TNF-alpha, IL-5, IL-6, IL-10, and IL-13) by a large number of these TCC. Upon analysis of 139 M. leprae-responsive TCC, we observed a positive correlation in the coproduction of IFN-gamma/TNF-alpha (r = 0.81), and in that of IL-4/IL-5 (r = 0.83), IL-4/IL-13 (r = 0.80), and IL-5/IL-13 (r = 0.82). Polarized type 1-like TCC produced dominantly IFN-gamma/TNF-alpha, and polarized type 2-like TCC predominantly IL-4/IL-5/IL-13. Most type 0-like TCC produced both sets of cytokines. In contrast, type 1- and type 2-like subsets of M. leprae-nonresponsive TCC (n = 58) did not show the same coexpression of these cytokines. Furthermore, when the differential expression of a broad panel of cytokines by individual M. leprae-responsive TCC is considered, it appeared that additional phenotypes could be recognized. These results suggested that distinct isotypes of type 1- and type 2-like T cells, based on the secretion of a panel of cytokines, may reflect M. leprae-specific characteristics.

Reversal reaction in borderline leprosy is associated with a polarized shift to type 1-like Mycobacterium leprae T cell reactivity in lesional skin: a follow-up study

Borderline leprosy patients often undergo acute changes in immune reactivity that manifest as reversal reaction (RR) in the course of the disease. RR is associated with an exacerbated local delayed-type cellular immune response to Mycobacterium leprae and is responsible for severe tissue damage. We investigated whether RR episodes are associated with a change in T cell subsets in the lesional skin with regard to their cytokine secretion profiles. M. leprae-responsive T cell lines and thereafter T cell clones (TCC) were generated from the lesional skin of seven untreated borderline leprosy patients (with or without RR) and again from three of these patients experiencing RR during treatment. The phenotypes of the M. leprae-responsive TCC were either CD4+, CD8+, CD4-/CD8+/TCR gammadelta+, or CD4-/CD8-/TCR gammadelta+, although most of them were CD4+. Regardless of the clinical status of the untreated patients, a major subset of the M. leprae-responsive TCC was type 0-like and produced both IFN-gamma and IL-4. Interestingly, in all three patients who experienced a (re)occurrence of RR during treatment after the first analysis, a clear shift to polarized IFN-gamma production by the M. leprae-responsive TCC (type 1-like) was observed. This shift in T cell subsets was also reflected in the observed decrease in serum IgG and IgM levels of the same patients during RR. These finding indicate that CD4+ M. leprae-responsive T cells with a polarized type 1-like phenotype might be responsible for the immune-mediated tissue damage occurring during RR.

Reversal reaction in borderline leprosy is associated with a polarized shift to type 1-like Mycobacterium leprae T cell reactivity in lesional skin: a follow-up study

Borderline leprosy patients often undergo acute changes in immune reactivity that manifest as reversal reaction (RR) in the course of the disease. RR is associated with an exacerbated local delayed-type cellular immune response to Mycobacterium leprae and is responsible for severe tissue damage. We investigated whether RR episodes are associated with a change in T cell subsets in the lesional skin with regard to their cytokine secretion profiles. M. leprae-responsive T cell lines and thereafter T cell clones (TCC) were generated from the lesional skin of seven untreated borderline leprosy patients (with or without RR) and again from three of these patients experiencing RR during treatment. The phenotypes of the M. leprae-responsive TCC were either CD4+, CD8+, CD4-/CD8+/TCR gammadelta+, or CD4-/CD8-/TCR gammadelta+, although most of them were CD4+. Regardless of the clinical status of the untreated patients, a major subset of the M. leprae-responsive TCC was type 0-like and produced both IFN-gamma and IL-4. Interestingly, in all three patients who experienced a (re)occurrence of RR during treatment after the first analysis, a clear shift to polarized IFN-gamma production by the M. leprae-responsive TCC (type 1-like) was observed. This shift in T cell subsets was also reflected in the observed decrease in serum IgG and IgM levels of the same patients during RR. These finding indicate that CD4+ M. leprae-responsive T cells with a polarized type 1-like phenotype might be responsible for the immune-mediated tissue damage occurring during RR.

Generation of a human melanocyte cell line by introduction of HPV16 E6 and E7 genes

Availability of a standard human melanocyte cell line with unlimited growth potential and otherwise normal melanocytic properties will greatly facilitate research in melanocyte biology and in vitro studies on the etiology of pigmentary disorders and melanoma. Using a retroviral vector, E6 and E7 open reading frames of human papilloma virus type 16 (HPV 16) have been introduced into cultured normal human melanocytes. Cells selected by increased resistance to geneticin conveyed by the vector and expressing E6E7 mRNA have been cloned to ensure genetic homogeneity. Since their establishment as primary cells, cloned PIG1 cells have undergone more than twice the amount of population doublings of senescent parental cells. Moreover, in passage numbers when parental cells had become senescent, proliferation of clonal cells was retained at levels exceeding those of normal human melanocytes in third passage by 100%. Further characterization has revealed that the cells remain dependent on tetradecanoyl phorbol 13-acetate (TPA) for growth and do not proliferate in soft agar nor form tumors in nude mice. The antigenic profile of the cells was slightly altered as compared to parental cells, but was incomparable to that of M14 melanoma cells. Importantly, PIG1 cells contain more melanin pigment than parental cells.