Chromatin and DNA methylation dynamics during retinoic acid-induced RET gene transcriptional activation in neuroblastoma cells.

Although it is well known that RET gene is strongly activated by retinoic acid (RA) in neuroblastoma cells, the mechanisms underlying such activation are still poorly understood. Here we show that a complex series of molecular events, that include modifications of both chromatin and DNA methylation state, accompany RA-mediated RET activation. Our results indicate that the primary epigenetic determinants of RA-induced RET activation differ between enhancer and promoter regions. At promoter region, the main mark of RET activation was the increase of H3K4me3 levels while no significant changes of the methylation state of H3K27 and H3K9 were observed. At RET enhancer region a bipartite chromatin domain was detected in unstimulated cells and a prompt demethylation of H3K27me3 marked RET gene activation upon RA exposure. Moreover, ChIP experiments demonstrated that EZH2 and MeCP2 repressor complexes were associated to the heavily methylated enhancer region in the absence of RA while both complexes were displaced during RA stimulation. Finally, our data show that a demethylation of a specific CpG site at the enhancer region could favor the displacement of MeCP2 from the heavily methylated RET enhancer region providing a novel potential mechanism for transcriptional regulation of methylated RA-regulated loci.

Extracellular guanosine and GTP promote expression of differentiation markers and induce S-phase cell-cycle arrest in human SH-SY5Y neuroblastoma cells.

SH-SY5Y neuroblastoma cells, a model for studying neuronal differentiation, are able to differentiate into either cholinergic or dopaminergic/adrenergic phenotypes depending on media conditions. Using this system, we asked whether guanosine (Guo) or guanosine-5'-triphosphate (GTP) are able to drive differentiation towards one particular phenotype. Differentiation was determined by evaluating the frequency of cells bearing neurites and assessing neurite length after exposure to different concentrations of Guo or GTP for different durations. After 6 days, 0.3 mM Guo or GTP induced a significant increase in the number of cells bearing neurites and increased neurite length. Western blot analyses confirmed that purines induced differentiation; cells exposed to purines showed increases in the levels of GAP43, MAP2, and tyrosine hydroxylase. Proliferation assays and cytofluorimetric analyses indicated a significant anti-proliferative effect of purines, and a concentration-dependent accumulation of cells in S-phase, starting after 24 h of purine exposure and extending for up to 6 days. A transcriptional profile analysis using gene arrays showed that an up-regulation of cyclin E2/cdk2 evident after 24 h was responsible for S-phase entry, and a concurrent down-regulation of cell-cycle progression-promoting cyclin B1/B2 prevented S-phase exit. In addition, patch-clamp recordings revealed that 0.3 mM Guo or GTP, after 6 day incubation, significantly decreased Na(+) currents. In conclusion, we showed Guo- and GTP-induced cell-cycle arrest in neuroblastoma cells and suggest that this makes these cells more responsive to differentiation processes that favor the dopaminergic/adrenergic phenotype.

HAND1 gene expression is negatively regulated by the High Mobility Group A1 proteins and is drastically reduced in human thyroid carcinomas.

HMGA1 proteins exert their major physiological function during embryonic development and play a critical role in neoplastic transformation. Here, we show that Hand1 gene, which codes for a transcription factor crucial for differentiation of trophoblast giant cells and heart development, is upregulated in hmga1 minus embryonic stem cells. We demonstrate that HMGA1 proteins bind directly to Hand1 promoter both in vitro and in vivo and inhibit Hand1 promoter activity. We have also investigated HAND1 expression in human thyroid carcinoma cell lines and tissues, in which HMGA proteins are overexpressed, with respect to normal thyroid; an inverse correlation between HMGA1 and HAND1 expression was found in all thyroid tumor histotypes. A correlation between HAND1 gene repression and promoter hypermethylation was found in anaplastic carcinomas but not in other thyroid tumor histotypes. Therefore, we can hypothesize that HMGA1 overexpression plays a key role on HAND1 silencing in differentiated thyroid carcinomas and that promoter hypermethylation occurs in later stages of thyroid tumor progression. Finally, the restoration of the HAND1 gene expression reduces the clonogenic ability of two human thyroid carcinoma-derived cell lines, suggesting that HAND1 downregulation may have a role in the process of thyroid carcinogenesis.

A Brazilian registry of juvenile dermatomyositis: onset features and classification of 189 cases.

OBJECTIVE: To describe onset features, classification and treatment of juvenile dermatomyositis (JDM) and juvenile polymyositis (JPM) from a multicentre registry. METHODS: Inclusion criteria were onset age lower than 18 years and a diagnosis of any idiopathic inflammatory myopathy (IIM) by attending physician. Bohan & Peter (1975) criteria categorisation was established by a scoring algorithm to define JDM and JPM based on clinical protocol data. RESULTS: Of the 189 cases included, 178 were classified as JDM, 9 as JPM (19.8: 1) and 2 did not fit the criteria; 6.9% had features of chronic arthritis and connective tissue disease overlap. Diagnosis classification agreement occurred in 66.1%. Median onset age was 7 years, median follow-up duration was 3.6 years. Malignancy was described in 2 (1.1%) cases. Muscle weakness occurred in 95.8%; heliotrope rash 83.5%; Gottron plaques 83.1%; 92% had at least one abnormal muscle enzyme result. Muscle biopsy performed in 74.6% was abnormal in 91.5% and electromyogram performed in 39.2% resulted abnormal in 93.2%. Logistic regression analysis was done in 66 cases with all parameters assessed and only aldolase resulted significant, as independent variable for definite JDM (OR=5.4, 95%CI 1.2-24.4, p=0.03). Regarding treatment, 97.9% received steroids; 72% had in addition at least one: methotrexate (75.7%), hydroxychloroquine (64.7%), cyclosporine A (20.6%), IV immunoglobulin (20.6%), azathioprine (10.3%) or cyclophosphamide (9.6%). In this series 24.3% developed calcinosis and mortality rate was 4.2%. CONCLUSION: Evaluation of predefined criteria set for a valid diagnosis indicated aldolase as the most important parameter associated with definite JDM category. In practice, prednisone-methotrexate combination was the most indicated treatment.

DNA methylation in intron 1 of the frataxin gene is related to GAA repeat length and age of onset in Friedreich ataxia patients.

BACKGROUND: The most frequent mutation of Friedreich ataxia (FRDA) is the abnormal expansion of a GAA repeat located within the first intron of FXN gene. It is known that the length of GAA is directly correlated with disease severity. The effect of mutation is a severe reduction of mRNA. Recently, a link among aberrant CpG methylation, chromatin organisation and GAA repeat was proposed. METHODS: In this study, using pyrosequencing technology, we have performed a quantitative analysis of the methylation status of five CpG sites located within the region upstream of GAA repeat, in 67 FRDA patients. RESULTS: We confirm previous observation about differences in the methylation degree between FRDA individuals and controls. We showed a direct correlation between CpG methylation and triplet expansion size. Significant differences were found for each CpG tested (ANOVA p<0.001). These differences were largest for CpG1 and CpG2: 84.45% and 76.80%, respectively, in FRDA patients compared to 19.65% and 23.34% in the controls. Most importantly, we found a strong inverse correlation between CpG2 methylation degree and age of onset (Spearman's rho = -0.550, p<0.001). CONCLUSION: Because epigenetic changes may cause or contribute to gene silencing, our data may have relevance for the therapeutic approach to FRDA. Since the analysis can be performed in peripheral blood leucocytes (PBL), evaluation of the methylation status of specific CpG sites in FRDA patients could be a convenient biomarker.

Risk factors for amenorrhea in juvenile systemic lupus erythematosus (JSLE): a Brazilian multicentre cohort study.

We evaluated the prevalence and clinical associations of amenorrhea in 298 female juvenile systemic lupus erythematosus (JSLE) patients (ACR criteria) followed in 12 Brazilian Paediatric Rheumatology centres. Amenorrhea was observed in 35 patients (11.7%) with a mean duration of 7.2 +/- 3.6 months. The hormones were performed in 32/35 patients and none of them had FSH and LH levels above and estradiol below the normal range according to pubertal changes. JSLE patients with amenorrhea were younger (15.04 +/- 2.5 versus 17.8 +/- 3.1 years; P = 0.001), and had a shorter period of time between menarche and current age (3.4 +/- 2.9 versus 6.7 +/- 5.4 years; P = 0.001). Interestingly, the frequency, cumulative dose, number of pulses and duration of intravenous cyclophosphamide treatment were alike in patients with and without amenorrhea (P > 0.05). In contrast, patients with amenorrhea had significantly higher SLEDAI (P = 0.01) and SLICC/ACR-DI (P = 0.024) scores compared to those without this condition. Independent risk factors identified by multivariate analysis were higher SLEDAI (OR = 1.059; CI = 1.004-1.116; P = 0.034) and SLICC/ACR-DI (OR = 2.125; IC = 1.373-3.291; P = 0.001) scores. Our data suggest that in spite of immunosuppressive therapy, JSLE patients have an adequate ovarian follicular reserve and amenorrhea is particularly associated with disease activity and damage.

Thyroid function and serum prolactin levels in patients with juvenile systemic lupus erythematosus.

OBJECTIVE: To evaluate both thyroid function and serum prolactin levels in patients with juvenile systemic lupus erythematosus (JSLE) and to detect possible correlation with disease activity. METHODS: Forty-two JSLE patients (3-15 years old at disease onset), twenty-two pubertal. All patients were evaluated according their clinical manifestations and disease activity. We determined serum prolactin, thyroid-stimulating hormone (TSH), T4, free T4, T3, thyroid peroxidasis and thyreoglobulin antibodies in all patients and controls. Thyroid ultrasonography was performed in the patients. RESULTS: We did not observe any difference in thyroid hormone and prolactin levels between patients and controls. One patient with JSLE presented with hyperthyroidism and six had thyroid antibodies. We observed abnormalities by ultrasonography in four patients (9.3%), specially heterogeneity of the gland echotexture. We did not find any correlation between prolactin levels, clinical manifestations or disease activity. CONCLUSIONS: Evaluation of thyroid function should not be routine for JSLE patients. Thyroid hormones and prolactin should be measured only in patients with clinical manifestations of hypo- or hyperthyroidism.

Crosscultural reliability of the Childhood Health Assessment Questionnaire.

OBJECTIVE: To translate into Portuguese the Childhood Health Assessment Questionnaire and to evaluate the reliability of the Portuguese version. METHODS: The original questionnaire was translated into Portuguese, without modifications, and it was administered to 53 children with juvenile rheumatoid arthritis and their parents. The reproducibility and construct validity were studied. RESULTS: We observed satisfactory Spearman's correlation coefficients among the instrument's score, a pain score (visual analog scale) and conventional clinical variables commonly used by the pediatric rheumatologists: disease activity index, number of involved joints, American College of Rheumatology functional class, and erythrocyte sedimentation rate. The test-retest reliability was established. CONCLUSION: Our results provide evidence of the reliability of the Portuguese version of the Childhood Health Assessment Questionnaire.

Modulation by ST 789 of in vitro lymphocyte activation and cytokine production.

Our results indicate that ST 789 exhibits complex immunomodulant properties. In fact, we found that ST 789 inhibits the expression of activation antigens, such as interleukin-2 and transferrin receptors by peripheral blood mononuclear cells (PBMCs) from healthy subjects following mitogen stimulation, but we were not able to detect under the same experimental conditions any effect on the in vitro production of soluble CD8 antigen and of interleukin-4 as well as on the proliferative response of antigen-specific and autoreactive human T cell lines. Finally, we showed that ST 789 is able to strongly enhance the in vitro production of interleukin-6 by PHA-stimulated PBMCs. The reduced expression of activation antigens in the presence of ST 789 does not seem to be mediated by CD8+ suppressor T lymphocytes, as indicated by the normal soluble CD8 levels in culture media, but rather reflects a direct inhibitory action on T helper proliferation and likely on interleukin-2 secretion. The strong enhancement by ST 789 of the in vitro interleukin-6 production seems to indicate the most relevant possibility of clinical applications in human diseases.

Cytokine production in patients with monoclonal gammapathies.

Increased interleukin-6 levels in culture media of mitogen-driven non adherent peripheral blood mononuclear cells were measurable in patients with monoclonal gammapathies of unknown significance but not in patients with multiple myeloma, indicating that in the former circulating mononuclear cells other than monocytes are involved in producing interleukin-6. Increased interleukin-4 levels were detected in supernatants of mitogen-driven peripheral blood mononuclear cells from patients with monoclonal gammapathies of unknown significance and from patients with multiple myeloma. The further increased interleukin-4 content in supernatants of non adherent cell cultures of multiple myeloma patients only suggests a somewhat inhibitory role of monocytes on interleukin-4 production, at least in multiple myeloma. Undetectable interleukin-2 levels in culture media were found in patients with monoclonal gammapathies of unknown significance and in patients with multiple myeloma. Serum levels of interleukin-6 and interleukin-2 were not measurable in either group, and interleukin-4 was detected only in a few patients. Our study suggests that in monoclonal gammapathies peripheral blood mononuclear cells could participate in producing cytokines involved in the regulation of B lymphocyte proliferation and differentiation. However, the pathophysiologic role in these patients of IL-6 and IL-4 in vitro, and possibly in vivo, produced by circulating lymphocytes remains to be established.

Soluble interleukin-2 receptor, interleukin-2 and interleukin-4 in sera and supernatants from patients with progressive systemic sclerosis.

We studied the sera of patients with progressive systemic sclerosis (PSS) for elevated levels of soluble interleukin-2 receptor (sIL-2R), interleukin-2 (IL-2) and interleukin-4 (IL-4). We also measured IL-2, IL-4 and B cell growth factor (BCGF) activity in supernatants of peripheral blood mononuclear cells from the same patients. The finding of elevated serum sIL-2R and IL-2, and the increased levels of IL-2, IL-4 and BCGF activity in culture supernatants indicates that T lymphocyte hyperactivity likely play a major role in PSS. The failure to detect under our experimental conditions a direct proliferative effect of recombinant IL-2 on enriched normal B cells might suggest that IL-4 is the cytokine mainly responsible of the BCGF activity recovered in PSS supernatants.

Soluble CD8 antigen in systemic sclerosis.

In 15 patients suffering from systemic sclerosis (PSS) the function of CD8+ circulating lymphocytes was assayed by determining soluble CD8 antigen (sCD8) both in sera and in 48 hr PHA-conditioned media of peripheral blood mononuclear cells (PBMCs). Furthermore, the frequency of circulating activated CD8+ cells, which express DR antigens, interleukin-2 receptor, and transferrin-receptor, was determined by cytofluorographic analysis. The results of this preliminary study indicate that only in 6 PSS sera sCD8 was elevated as compared to healthy controls; furthermore, we found slightly increased sCD8 in culture media from PSS patients. The frequency of circulating activated CD8+ cells was similar both in PSS patients and in controls. Overall, our findings suggest that CD8+ cell activation is not a major phenomenon in PSS.

Evidence of drug interaction between cyclosporin A and H2-receptor antagonists (cimetidine, ranitidine and famotidine) in Sprague-Dawley rats.

H2-receptor antagonists, such as cimetidine (C), ranitidine (R) and famotidine (F) seem to be effective in the prevention and treatment of stress ulcer in transplant recipients receiving cyclosporin A (CyA). The aim of this study was to detect the possible synergistic nephro- and hepato-toxicity of these drugs, assaying the serum creatinine (SC), ALT, AST levels, and the histological features of 45 young male Sprague-Dawley rats, divided into nine groups of five rats each. After 10 days of treatment the results showed: (i) serum CyA levels were increased in the group receiving daily CyA (5 mg/kg) + R(5 mg/kg) (2430 +/- 403 ng/ml; p less than 0.05 vs. controls) and in the group receiving daily CyA (5 mg/kg) +/- C (10 mg/kg) (2440 +/- 265 ng/ml; p less than 0.01 vs. controls); (ii) ALT and AST levels were increased in this latter group (ALT 223 +/- 133 UL, AST 114.67 +/- 39 UL; p less than 0.01 vs. controls); (iii) SC levels were normal; and (iv) steatosis of the liver was observed in these two groups. These findings suggest that C and R, but not F, may inhibit the hepatic cytochromes P-450 which are involved in the oxidative metabolism of the drugs. Furthermore, the high serum CyA levels seem to play a major role in the appearance of biochemical and histological damage to the liver.