RESUMO
Juvenile myelomonocytic leukaemia (JMML) is characterized by gene variants that deregulate the RAS signalling pathway. Children with neurofibromatosis type 1 (NF-1) carry a defective NF1 allele in the germline and are predisposed to JMML, which presumably requires somatic inactivation of the NF1 wild-type allele. Here we examined the two-hit concept in leukaemic cells of 25 patients with JMML and NF-1. Ten patients with JMML/NF-1 exhibited a NF1 loss-of-function variant in combination with uniparental disomy of the 17q arm. Five had NF1 microdeletions combined with a pathogenic NF1 variant and nine carried two compound-heterozygous NF1 variants. We also examined 16 patients without clinical signs of NF-1 and no variation in the JMML-associated driver genes PTPN11, KRAS, NRAS or CBL (JMML-5neg) and identified eight patients with NF1 variants. Three patients had microdeletions combined with hemizygous NF1 variants, three had compound-heterozygous NF1 variants and two had heterozygous NF1 variants. In addition, we found a high incidence of secondary ASXL1 and/or SETBP1 variants in both groups. We conclude that the clinical diagnosis of JMML/NF-1 reliably indicates a NF1-driven JMML subtype, and that careful NF1 analysis should be included in the genetic workup of JMML even in the absence of clinical evidence of NF-1.
Assuntos
Leucemia Mielomonocítica Juvenil , Neurofibromatose 1 , Criança , Humanos , Leucemia Mielomonocítica Juvenil/genética , Neurofibromatose 1/genética , Mutação , Transdução de Sinais , Genes Supressores de TumorRESUMO
Monosomy 7 is the most common cytogenetic abnormality in pediatric myelodysplastic syndrome (MDS) and associated with a high risk of disease progression. However, in young children, spontaneous loss of monosomy 7 with concomitant hematologic recovery has been described, especially in the presence of germline mutations in SAMD9 and SAMD9L genes. Here, we report on our experience of close surveillance instead of upfront hematopoietic stem cell transplantation (HSCT) in seven patients diagnosed with SAMD9L syndrome and monosomy 7 at a median age of 0.6 years (range, 0.4-2.9). Within 14 months from diagnosis, three children experienced spontaneous hematological remission accompanied by a decrease in monosomy 7 clone size. Subclones with somatic SAMD9L mutations in cis were identified in five patients, three of whom attained hematological remission. Two patients acquired RUNX1 and EZH2 mutations during the observation period, of whom one progressed to myelodysplastic syndrome with excess of blasts (MDS-EB). Four patients underwent allogeneic HSCT at a median time of 26 months (range, 14-40) from diagnosis for MDSEB, necrotizing granulomatous lymphadenitis, persistent monosomy 7, and severe neutropenia. At last follow-up, six patients were alive, while one passed away due to transplant-related causes. These data confirm previous observations that monosomy 7 can be transient in young children with SAMD9L syndrome. However, they also indicate that delaying HSCT poses a substantial risk of severe infection and disease progression. Finally, surveillance of patients with SAMD9L syndrome and monosomy 7 is critical to define the evolving genetic landscape and to determine the appropriate timing of HSCT (clinicaltrials gov. Identifier: NCT00662090).
Assuntos
Deleção Cromossômica , Síndromes Mielodisplásicas , Humanos , Criança , Pré-Escolar , Lactente , Remissão Espontânea , Síndromes Mielodisplásicas/diagnóstico , Síndromes Mielodisplásicas/genética , Síndromes Mielodisplásicas/terapia , Progressão da Doença , Fatores de Transcrição/genética , Monossomia , Cromossomos Humanos Par 7/genética , Peptídeos e Proteínas de Sinalização Intracelular/genéticaRESUMO
Germline SAMD9 and SAMD9L mutations (SAMD9/9Lmut) predispose to myelodysplastic syndromes (MDS) with propensity for somatic rescue. In this study, we investigated a clinically annotated pediatric MDS cohort (n = 669) to define the prevalence, genetic landscape, phenotype, therapy outcome and clonal architecture of SAMD9/9L syndromes. In consecutively diagnosed MDS, germline SAMD9/9Lmut accounted for 8% and were mutually exclusive with GATA2 mutations present in 7% of the cohort. Among SAMD9/9Lmut cases, refractory cytopenia was the most prevalent MDS subtype (90%); acquired monosomy 7 was present in 38%; constitutional abnormalities were noted in 57%; and immune dysfunction was present in 28%. The clinical outcome was independent of germline mutations. In total, 67 patients had 58 distinct germline SAMD9/9Lmut clustering to protein middle regions. Despite inconclusive in silico prediction, 94% of SAMD9/9Lmut suppressed HEK293 cell growth, and mutations expressed in CD34+ cells induced overt cell death. Furthermore, we found that 61% of SAMD9/9Lmut patients underwent somatic genetic rescue (SGR) resulting in clonal hematopoiesis, of which 95% was maladaptive (monosomy 7 ± cancer mutations), and 51% had adaptive nature (revertant UPD7q, somatic SAMD9/9Lmut). Finally, bone marrow single-cell DNA sequencing revealed multiple competing SGR events in individual patients. Our findings demonstrate that SGR is common in SAMD9/9Lmut MDS and exemplify the exceptional plasticity of hematopoiesis in children.
Assuntos
Evolução Clonal/genética , Hematopoiese Clonal/genética , Peptídeos e Proteínas de Sinalização Intracelular/genética , Síndromes Mielodisplásicas/genética , Proteínas Supressoras de Tumor/genética , Adolescente , Células da Medula Óssea/metabolismo , Criança , Pré-Escolar , Feminino , Fator de Transcrição GATA2/genética , Mutação em Linhagem Germinativa/genética , Células HEK293 , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Lactente , Estimativa de Kaplan-Meier , Masculino , Síndromes Mielodisplásicas/patologia , Análise de Célula ÚnicaRESUMO
Deficiency of the transcription factor GATA2 is a highly penetrant genetic disorder predisposing to myelodysplastic syndromes (MDS) and immunodeficiency. It has been recognized as the most common cause underlying primary MDS in children. Triggered by the discovery of a recurrent synonymous GATA2 variant, we systematically investigated 911 patients with phenotype of pediatric MDS or cellular deficiencies for the presence of synonymous alterations in GATA2. In total, we identified nine individuals with five heterozygous synonymous mutations: c.351C>G, p.T117T (N = 4); c.649C>T, p.L217L; c.981G>A, p.G327G; c.1023C>T, p.A341A; and c.1416G>A, p.P472P (N = 2). They accounted for 8.2% (9/110) of cases with GATA2 deficiency in our cohort and resulted in selective loss of mutant RNA. While for the hotspot mutation (c.351C>G) a splicing error leading to RNA and protein reduction was identified, severe, likely late stage RNA loss without splicing disruption was found for other mutations. Finally, the synonymous mutations did not alter protein function or stability. In summary, synonymous GATA2 substitutions are a new common cause of GATA2 deficiency. These findings have broad implications for genetic counseling and pathogenic variant discovery in Mendelian disorders.
Assuntos
Deficiência de GATA2/genética , Fator de Transcrição GATA2/deficiência , Fator de Transcrição GATA2/genética , RNA/genética , Mutação Silenciosa/genética , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Estudos de Associação Genética , Predisposição Genética para Doença/genética , Mutação em Linhagem Germinativa/genética , Heterozigoto , Humanos , Síndromes de Imunodeficiência/genética , Masculino , Síndromes Mielodisplásicas/genética , Fenótipo , Adulto JovemRESUMO
Reactive oxygen species (ROS) are implicated in the aetiology of interstitial lung disease (ILD). We investigated the role of large-scale somatically acquired mutations in mitochondrial DNA (mtDNA) and consecutive respiratory chain dysfunction as a trigger of ROS-formation and lung fibrosis. Mitochondria were analysed in lung biopsies from 30 patients with idiopathic or connective tissue disease (CTD)-related ILD and 13 controls. In 17 patients we had paired biopsies from upper and lower lobes. Control samples were taken from lung cancer resections without interstitial fibrosis. Malondialdehyde, a marker of ROS-formation, was elevated in ILD-biopsies (p = 0.044). The activity of the mitochondrial respiratory chain (cytochrome c-oxidase/succinate dehydrogenase [COX/SDH]-ratio) was depressed in ILD (median = 0.10,) compared with controls (0.12, p < 0.001), as was the expression of mtDNA-encoded COX-subunit-2 protein normalized for the nucleus-encoded COX-subunit-4 (COX2/COX4-ratio; ILD-median = 0.6; controls = 2.2; p < 0.001). Wild-type mtDNA copies were slightly elevated in ILD (p = 0.088). The common mtDNA deletion was only present at low levels in controls (median = 0%) and at high levels in ILD (median = 17%; p < 0.001). In ILD-lungs with paired biopsies, lower lobes contained more malondialdehyde and mtDNA deletions than upper lobes and had lower COX2/COX4-ratios and COX/SDH-ratios (all p < 0.001). Acquired mtDNA-mutations and consecutive respiratory chain dysfunction may both trigger and perpetuate ROS-formation in ILD.
Assuntos
Doenças do Tecido Conjuntivo/patologia , DNA Mitocondrial/genética , Doenças Pulmonares Intersticiais/patologia , Mutação , Espécies Reativas de Oxigênio/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Biópsia , Estudos de Casos e Controles , Doenças do Tecido Conjuntivo/genética , Doenças do Tecido Conjuntivo/metabolismo , Transporte de Elétrons , Feminino , Humanos , Doenças Pulmonares Intersticiais/genética , Doenças Pulmonares Intersticiais/metabolismo , Masculino , Pessoa de Meia-IdadeRESUMO
Familial myelodysplastic syndromes arise from haploinsufficiency of genes involved in hematopoiesis and are primarily associated with early-onset disease. Here we describe a familial syndrome in seven patients from four unrelated pedigrees presenting with myelodysplastic syndrome and loss of chromosome 7/7q. Their median age at diagnosis was 2.1 years (range, 1-42). All patients presented with thrombocytopenia with or without additional cytopenias and a hypocellular marrow without an increase of blasts. Genomic studies identified constitutional mutations (p.H880Q, p.R986H, p.R986C and p.V1512M) in the SAMD9L gene on 7q21, with decreased allele frequency in hematopoiesis. The non-random loss of mutated SAMD9L alleles was attained via monosomy 7, deletion 7q, UPD7q, or acquired truncating SAMD9L variants p.R1188X and p.S1317RfsX21. Incomplete penetrance was noted in 30% (3/10) of mutation carriers. Long-term observation revealed divergent outcomes with either progression to leukemia and/or accumulation of driver mutations (n=2), persistent monosomy 7 (n=4), and transient monosomy 7 followed by spontaneous recovery with SAMD9L-wildtype UPD7q (n=2). Dysmorphic features or neurological symptoms were absent in our patients, pointing to the notion that myelodysplasia with monosomy 7 can be a sole manifestation of SAMD9L disease. Collectively, our results define a new subtype of familial myelodysplastic syndrome and provide an explanation for the phenomenon of transient monosomy 7. Registered at: www.clinicaltrials.gov; #NCT00047268.
Assuntos
Deleção Cromossômica , Síndromes Mielodisplásicas/genética , Proteínas Supressoras de Tumor/genética , Adolescente , Adulto , Criança , Pré-Escolar , Cromossomos Humanos Par 7 , Saúde da Família , Feminino , Humanos , Lactente , Masculino , Linhagem , Penetrância , Trombocitopenia , Adulto JovemRESUMO
Reactive oxygen species (ROS) have been implemented in the etiology of pulmonary fibrosis (PF) in systemic sclerosis. In the bleomycin model, we evaluated the role of acquired mutations in mitochondrial DNA (mtDNA) and respiratory chain defects as a trigger of ROS formation and fibrogenesis. Adult male Wistar rats received a single intratracheal instillation of bleomycin and their lungs were examined at different time points. Ashcroft scores, collagen and TGFß1 levels documented a delayed onset of PF by day 14. In contrast, increased malon dialdehyde as a marker of ROS formation was detectable as early as 24 hours after bleomycin instillation and continued to increase. At day 7, lung tissue acquired significant amounts of mtDNA deletions, translating into a significant dysfunction of mtDNA-encoded, but not nucleus-encoded respiratory chain subunits. mtDNA deletions and markers of mtDNA-encoded respiratory chain dysfunction significantly correlated with pulmonary TGFß1 concentrations and predicted PF in a multivariate model.
Assuntos
DNA Mitocondrial/genética , Mutagênese , Fibrose Pulmonar/genética , Escleroderma Sistêmico/genética , Animais , Bleomicina , Western Blotting , Modelos Animais de Doenças , Transporte de Elétrons/genética , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Humanos , Pulmão/metabolismo , Pulmão/patologia , Masculino , Microscopia Eletrônica , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Fibrose Pulmonar/induzido quimicamente , Fibrose Pulmonar/metabolismo , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Escleroderma Sistêmico/induzido quimicamente , Escleroderma Sistêmico/metabolismo , Fatores de Tempo , Fator de Crescimento Transformador beta1/metabolismoRESUMO
BACKGROUND: The use of zidovudine is associated with a loss of subcutaneous adipose tissue (SAT). We assessed if zidovudine treatment also affects visceral adipose tissue (VAT) and if uridine supplementation abrogates the adverse effects of zidovudine on VAT. METHODS: Rats were fed zidovudine for 21 weeks with or without simultaneous uridine supplementation. Control animals did not receive zidovudine, or were treated with uridine alone. Changes in SAT and VAT were monitored by magnetic resonance imaging. Adipose tissue was examined for structural and molecular signs of mitochondrial toxicity. RESULTS: Zidovudine induced lipoatrophy in SAT and fat hypertrophy in VAT. Compared with controls zidovudine-exposed VAT adipocytes had increased diameters, microvesicular steatosis and enlarged mitochondria with disrupted crystal architecture on electron microscopy. VAT adipocyte mitochondrial DNA (mtDNA) copy numbers were diminished, as were mtDNA-encoded respiratory chain proteins. The 'common' mtDNA deletion was detected in high frequencies in zidovudine treated animals, but not in the controls. Although mtDNA depletion was more profound in SAT compared with VAT, the 'common' deletion tended to be more frequent in the VAT than in the SAT. Uridine coadministration abrogated all effects of zidovudine on VAT and SAT pathology. CONCLUSIONS: Zidovudine induces a gain of intra-abdominal fat in association with quantitative and qualitative alterations of the mitochondrial genome and impaired expression of mtDNA-encoded respiratory chain components, indicating that zidovudine may contribute to abdominal fat hypertrophy in HIV-infected patients. In this rodent model, uridine supplementation abrogates both SAT and VAT pathology induced by zidovudine.
Assuntos
Adiposidade/efeitos dos fármacos , Fármacos Anti-HIV/efeitos adversos , Gordura Intra-Abdominal/patologia , Lipodistrofia/etiologia , Lipodistrofia/patologia , Mitocôndrias/efeitos dos fármacos , Zidovudina/efeitos adversos , Tecido Adiposo/efeitos dos fármacos , Tecido Adiposo/patologia , Animais , Fármacos Anti-HIV/administração & dosagem , Ciclo-Oxigenase 1/genética , Ciclo-Oxigenase 1/metabolismo , DNA Mitocondrial/genética , Modelos Animais de Doenças , Dosagem de Genes/efeitos dos fármacos , Lipodistrofia/diagnóstico , Imageamento por Ressonância Magnética , Masculino , Mitocôndrias/genética , Mitocôndrias/metabolismo , Ratos , Zidovudina/administração & dosagemRESUMO
OBJECTIVE: We aim to evaluate the mechanisms of rosiglitazone-induced fat recovery in HIV+ patients with lipoatrophy on thymidine Nucleoside Reverse Transcriptase Inhibitors (NRTI) sparing regimens. METHOD: Measures of limb fat (DXA), oxidative stress (F2 isoprostanes) and inflammation [High-sensitivity C-reactive protein (hsCRP), soluble Tumor Necrosis Factor Receptors (sTNFR)-I, sTNFR-II, and interleukin (IL)-6] were performed. Gluteal fat mitochondrial DNA (mtDNA) and peroxisome proliferator-activated receptor (PPAR)-γ RNA [expressed as PPAR-γ/Glyceraldehyde 6-Phosphate Dehydrogenase (GAPDH) RNA ratio] were measured by quantitative PCR. RESULT: 71 patients on thymidine NRTI-sparing regimens were randomized to rosiglitazone vs. placebo for 48 weeks. Duration off thymidine NRTIs was similar between groups. From week 0-48, limb fat increased significantly (p=0.02) more in the rosiglitazone than in the placebo group. Within both groups, F2-isoprostanes, sTNFR-I and sTNFR-II increased significantly (p ≤ 0.003), hsCRP decreased significantly (≤ 0.02), and IL-6 did not change. No differences were seen between groups in any of the inflammation markers. Fat mtDNA (copies/cell) increased nonsignificantly: +41(p=0.08) and +29(p=0.38) within rosiglitazone and placebo group; respectively. PPAR-γ/GAPDH ratio did not change within or between groups. CONCLUSION: Limb fat improvements seen after rosiglitazone were not associated with changes in mtDNA, oxidative or inflammation markers, or PPAR-γ expression. F2 isoprostanes and some of the inflammation markers worsened over time in these subjects on stable ART, regardless of the rosiglitazone assignment. Thus, lipoatrophy can be in part overcome by a separate pathway independent of mitochondrial DNA depletion, such as PPAR-γ.
RESUMO
INTRODUCTION: Skeletal muscle fiber composition and muscle energetics are not static and change in muscle disease. This study was performed to determine whether a mitochondrial myopathy is associated with adjustments in skeletal muscle fiber-type composition. METHODS: Ten rats were treated with zidovudine, an antiretroviral nucleoside reverse transcriptase inhibitor that induces a myopathy by interfering with mitochondrial functions. Soleus muscles were examined after 21 weeks of treatment. Ten untreated rats served as controls. RESULTS: Zidovudine induced a myopathy with mitochondrial DNA depletion, abnormalities in mitochondrial ultrastructure, and reduced cytochrome c oxidase activity. Mitochondrial DNA was disproportionally more diminished in type I compared with type II fibers, whereas atrophy predominated in type II fibers. Compared with those of controls, zidovudine-exposed soleus muscles contained an increased proportion (256%) of type II fibers, whereas neonatal myosin heavy chains remained repressed, indicating fiber-type transformation in the absence of regeneration. Microarray gene-expression analysis confirmed enhanced fast-fiber isoforms, repressed slow-fiber transcripts, and reduced neonatal fiber transcripts in the mitochondrial myopathy. Respiratory chain transcripts were diminished, whereas the enzymes of glycolysis and glycogenolysis were enhanced, indicating a metabolic adjustment from oxidative to glycolytic capacities. A coordinated regulation was found of transcription factors known to orchestrate type II fiber formation (upregulation of MyoD, Six1, Six2, Eya1, and Sox6, and downregulation of myogenin and ERRγ). CONCLUSIONS: The type I to type II fiber transformation in mitochondrial myopathy implicates mitochondrial function as a new regulator of skeletal muscle fiber type.
Assuntos
Transdiferenciação Celular , Transporte de Elétrons/fisiologia , Fibras Musculares de Contração Rápida/patologia , Fibras Musculares de Contração Lenta/patologia , Doenças Musculares/patologia , Doenças Musculares/fisiopatologia , Animais , Modelos Animais de Doenças , Masculino , Mitocôndrias Musculares/fisiologia , Mitocôndrias Musculares/ultraestrutura , Músculo Esquelético/patologia , Atrofia Muscular/patologia , Doenças Musculares/induzido quimicamente , Ratos , Ratos Wistar , Inibidores da Transcriptase Reversa/efeitos adversos , Zidovudina/efeitos adversosRESUMO
OBJECTIVE: To assess the impact of immunosuppressive therapy with cyclophosphamide (CYC) and rituximab (RTX) on serum immunoglobulin (Ig) concentrations and B lymphocyte counts in patients with ANCA-associated vasculitides (AAVs). METHODS: Retrospective analysis of Ig concentrations and peripheral B cell counts in 55 AAV patients. RESULTS: CYC treatment resulted in a decrease in Ig levels (median; interquartile range IQR) from IgG 12.8 g/L (8.15-15.45) to 9.17 g/L (8.04-9.90) (pâ=â0.002), IgM 1.05 g/L (0.70-1.41) to 0.83 g/L (0.60-1.17) (pâ=â0.046) and IgA 2.58 g/L (1.71-3.48) to 1.58 g/L (1-31-2.39) (pâ=â0.056) at a median follow-up time of 4 months. IgG remained significantly below the initial value at 14.5 months and 30 months analyses. Subsequent RTX treatment in patients that had previously received CYC resulted in a further decline in Ig levels from pre RTX IgG 9.84 g/L (8.71-11.60) to 7.11 g/L (5.75-8.77; pâ=â0.007), from pre RTX IgM 0.84 g/L (0.63-1.18) to 0.35 g/L (0.23-0.48; p<0.001) and from pre RTX IgA 2.03 g/L (1.37-2.50) to IgA 1.62 g/L (IQR 0.84-2.43; pâ=â0.365) 14 months after RTX. Treatment with RTX induced a complete depletion of B cells in all patients. After a median observation time of 20 months median B lymphocyte counts remained severely suppressed (4 B-cells/µl, 1.25-9.5, p<0.001). Seven patients (21%) that had been treated with CYC followed by RTX were started on Ig replacement because of severe bronchopulmonary infections and serum IgG concentrations below 5 g/L. CONCLUSIONS: In patients with AAVs, treatment with CYC leads to a decline in immunoglobulin concentrations. A subsequent RTX therapy aggravates the decline in serum immunoglobulin concentrations and results in a profoundly delayed B cell repopulation. Surveying patients with AAVs post CYC and RTX treatment for serum immunoglobulin concentrations and persisting hypogammaglobulinemia is warranted.
Assuntos
Vasculite Associada a Anticorpo Anticitoplasma de Neutrófilos/tratamento farmacológico , Vasculite Associada a Anticorpo Anticitoplasma de Neutrófilos/imunologia , Anticorpos Monoclonais Murinos/uso terapêutico , Linfócitos B/efeitos dos fármacos , Ciclofosfamida/uso terapêutico , Imunoglobulinas/sangue , Fatores Imunológicos/uso terapêutico , Adulto , Idoso , Anticorpos Monoclonais Murinos/farmacologia , Linfócitos B/imunologia , Ciclofosfamida/farmacologia , Feminino , Humanos , Fatores Imunológicos/farmacologia , Contagem de Linfócitos , Masculino , Pessoa de Meia-Idade , RituximabRESUMO
BACKGROUND: Complement receptor 2 (CR2/CD21) is part of the B-cell coreceptor and expressed by mature B cells and follicular dendritic cells. CD21 is a receptor for C3d-opsonized immune complexes and enhances antigen-specific B-cell responses. OBJECTIVE: Genetic inactivation of the murine CR2 locus results in impaired humoral immune responses. Here we report the first case of a genetic CD21 deficiency in human subjects. METHODS: CD21 protein expression was analyzed by means of flow cytometry and Western blotting. CD21 transcripts were quantified by using real-time PCR. The CD21 gene was sequenced. Wild-type and mutant CD21 cDNA expression was studied after transfection of 293T cells. Binding of EBV-gp350 or C3d-containing immune complexes and induction of calcium flux in CD21-deficient B cells were analyzed by means of flow cytometry. Antibody responses to protein and polysaccharide vaccines were measured. RESULTS: A 28-year-old man presented with recurrent infections, reduced class-switched memory B cells, and hypogammaglobulinemia. CD21 receptor expression was undetectable. Binding of C3d-containing immune complexes and EBV-gp350 to B cells was severely reduced. Sequence analysis revealed a compound heterozygous deleterious mutation in the CD21 gene. Functional studies with anti-immunoglobulin- and C3d-containing immune complexes showed a complete loss of costimulatory activity of C3d in enhancing suboptimal B-cell receptor stimulation. Vaccination responses to protein antigens were normal, but the response to pneumococcal polysaccharide vaccination was moderately impaired. CONCLUSIONS: Genetic CD21 deficiency adds to the molecular defects observed in human subjects with hypogammaglobulinemia.
Assuntos
Agamaglobulinemia/genética , Agamaglobulinemia/imunologia , Linfócitos B/metabolismo , Infecções/imunologia , Receptores de Complemento 3d/metabolismo , Adulto , Agamaglobulinemia/complicações , Agamaglobulinemia/diagnóstico , Complexo Antígeno-Anticorpo/metabolismo , Linfócitos B/imunologia , Linfócitos B/patologia , Sinalização do Cálcio/genética , Complemento C3d/metabolismo , Análise Mutacional de DNA , Células HEK293 , Humanos , Imunidade Humoral/genética , Memória Imunológica/genética , Infecções/diagnóstico , Infecções/etiologia , Infecções/genética , Masculino , Ligação Proteica/genética , Receptores de Complemento 3d/genética , Receptores de Complemento 3d/imunologia , Deleção de Sequência/genética , Transgenes/genética , Proteínas da Matriz Viral/metabolismoRESUMO
OBJECTIVE: Long-term antiretroviral treatment with nucleoside analogue reverse transcriptase inhibitors (NRTI) may result in a cardiomyopathy due to mitochondrial DNA (mtDNA) depletion. An intact mitochondrial function is required for the synthesis of intramyocardial pyrimidine nucleotides, which in turn are building blocks of mtDNA. We investigated if NRTI-related cardiomyopathy can be prevented with pyrimidine precursors. METHODS: Mice were fed with zidovudine or zalcitabine with or without simultaneous Mitocnol, a dietary supplement with high uridine bioavailability. Myocardia were examined after 9 weeks. RESULTS: Both NRTI induced a cardiomyopathy with mitochondrial enlargement, a disrupted cristal architecture on electron microscopy and diminished myocardial mtDNA copy numbers. The myocardial mtDNA-encoded cytochrome c-oxidase I subunit was impaired more profoundly than the nucleus-encoded cytochrome c-oxidase IV subunit. The myocardial formation of reactive oxygen species and mtDNA mutations was enhanced in zidovudine and zalcitabine treated animals. Mitocnol attenuated or normalized all myocardial pathology when given with both NRTI, but by itself had no intrinsic effects and no apparent adverse effects. CONCLUSIONS: Zidovudine and zalcitabine induce a mitochondrial cardiomyopathy, which is antagonized with uridine supplementation, implicating pyrimidine pool depletion in its pathogenesis. Pyrimidine pool replenishment may be exploited clinically because uridine is well tolerated.
Assuntos
Cardiomiopatias/induzido quimicamente , Cardiotoxinas/toxicidade , Coração/efeitos dos fármacos , Mitocôndrias Cardíacas/efeitos dos fármacos , Pirimidinas/metabolismo , Inibidores da Transcriptase Reversa/toxicidade , Animais , Fármacos Anti-HIV/administração & dosagem , Fármacos Anti-HIV/farmacologia , Fármacos Anti-HIV/toxicidade , Variações do Número de Cópias de DNA/efeitos dos fármacos , DNA Mitocondrial/efeitos dos fármacos , DNA Mitocondrial/genética , Suplementos Nutricionais , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Infecções por HIV/tratamento farmacológico , Infecções por HIV/genética , Camundongos , Camundongos Endogâmicos BALB C , Mitocôndrias Cardíacas/ultraestrutura , Mutação , Nucleosídeos , Pirimidinas/administração & dosagem , Pirimidinas/farmacologia , Pirimidinas/uso terapêutico , Espécies Reativas de Oxigênio , Inibidores da Transcriptase Reversa/administração & dosagem , Inibidores da Transcriptase Reversa/farmacologia , Uridina/administração & dosagem , Uridina/farmacologia , Uridina/uso terapêutico , Zalcitabina/administração & dosagem , Zalcitabina/farmacologia , Zalcitabina/toxicidade , Zidovudina/administração & dosagem , Zidovudina/farmacologia , Zidovudina/toxicidadeRESUMO
BACKGROUND: Doxorubicin causes a chronic cardiomyopathy in which genetic and functional lesions of mitochondria accumulate in the long-term. A disrupted Ca2+ homeostasis is also implicated in doxorubicin cardiotoxicity. We investigated if the alterations in myocellular Ca2+ are primary or secondary to the respiratory chain dysfunction in chronic doxorubicin cardiomyopathy. METHODS AND RESULTS: A "long-observation group" of rats was treated with intravenous doxorubicin (1 mg/kg per week) for 7 weeks, starting at 11 weeks of age. Controls received equivalents of saline. A "short-observation group" received seven injections of doxorubicin, starting at 41 weeks of age. All rats were euthanized at 48 weeks of age. Only the long-observation rats developed a significant clinical, macroscopic, histological, and ultrastructural cardiomyopathy. Their intramyocardial cytochrome c oxidase (COX) activity was lowest; they had the highest loss of mitochondrial DNA (mtDNA) and its encoded respiratory chain subunit COX I, and the highest amount of ultrastructural and intracellular calcium accumulation resembling hydroxyapatite. The short-term-group hearts had fewer alterations of the cardiomyopathy score, COX-activity, and mtDNA-content than the long-observation group. Despite a measurable loss of mtDNA and its encoded respiratory chain activity, however, there was virtually no detectable calcium accumulation in the hearts of the short-term group. CONCLUSIONS: mtDNA depletion and secondary respiratory chain dysfunction precedes the precipitation of mitochondrial calcium deposits in chronic doxorubicin cardiotoxicity.
Assuntos
Antibióticos Antineoplásicos/toxicidade , Cálcio/metabolismo , Cardiomiopatias/induzido quimicamente , Doxorrubicina/toxicidade , Transporte de Elétrons/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Animais , Cardiomiopatias/metabolismo , Cardiomiopatias/patologia , DNA Mitocondrial/efeitos dos fármacos , Complexo IV da Cadeia de Transporte de Elétrons/efeitos dos fármacos , Masculino , Microscopia Eletrônica de Transmissão , Mitocôndrias Cardíacas/efeitos dos fármacos , Mitocôndrias Cardíacas/ultraestrutura , Ratos , Ratos WistarRESUMO
OBJECTIVE: Peripheral neuropathy and central nervous system neurodegeneration may result from the mitochondrial toxicity of some antiretroviral nucleoside analogues. We investigated whether this neuropathology may be antagonized by uridine supplementation in vivo. DESIGN: Because of the obvious difficulties in obtaining human neural tissues, the mitochondrial neurotoxicity of the nucleoside analogues was studied in mice. METHODS: BALB/C mice (7 weeks of age) were fed for 9 weeks with zalcitabine (13 mg/kg per day) or zidovudine (100 mg/kg per day) with or without mitocnol (340 mg/kg per day), a dietary supplement with high uridine bioavailability. Hippocampal and sciatic nerve mitochondria were analyzed. RESULTS: Zalcitabine and to a lesser extent zidovudine induced a significant peripheral neuropathy and encephalopathy with disrupted mitochondrial ultrastructure, depleted mitochondrial DNA, reduced levels of cytochrome c oxidase activity and diminished expression of mitochondrial DNA-encoded cytochrome c oxidase subunit I. Mitocnol had no intrinsic effects but attenuated or fully normalized all measured disorder of the peripheral and central nervous system. CONCLUSION: Zidovudine and zalcitabine induce a mitochondrial disorder in the peripheral and central nervous system, both of which are antagonized by uridine supplementation.
Assuntos
Fármacos Anti-HIV/efeitos adversos , Miopatias Mitocondriais/prevenção & controle , Uridina/farmacologia , Zalcitabina/efeitos adversos , Zidovudina/efeitos adversos , Administração Oral , Animais , DNA Mitocondrial/análise , DNA Mitocondrial/efeitos dos fármacos , Interações Medicamentosas , Peroxidação de Lipídeos/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Encefalomiopatias Mitocondriais/induzido quimicamente , Encefalomiopatias Mitocondriais/prevenção & controle , Miopatias Mitocondriais/induzido quimicamente , Miopatias Mitocondriais/genética , Uridina/administração & dosagemRESUMO
OBJECTIVES: Tenofovir disoproxil fumarate (tenofovir DF) use has been associated with renal dysfunction and Fanconi syndrome. Tenofovir is taken up into renal tubules by anion transporters where high intracellular drug concentration may induce a functionally relevant depletion of mitochondrial DNA (mtDNA). We investigated if tenofovir may induce renal mtDNA depletion and respiratory chain dysfunction. METHODS: Rats (n = 8) were gavaged daily with 100 mg x kg(-1) x d(-1) of tenofovir DF or didanosine. Kidneys and livers were examined after 8 weeks of treatment. RESULTS: The tenofovir group had significantly lower body and kidney weights than rats exposed to water or didanosine. Proximal but not distal tubules were of increased diameter and contained small lipid droplets. Tubular mitochondria were enlarged, and their crystal architecture was disrupted. Tenofovir-exposed kidneys contained low mtDNA copy numbers and impaired expression of mtDNA-encoded cytochrome c oxidase (COX) I but not nucleus-encoded COX IV subunits. Histochemistry demonstrated low tubular COX and nicotinamide adenine dinucleotide dehydrogenase (NADH-DH) activities, whereas succinate dehydrogenase activity was preserved. COX activity was preserved in the glomeruli of tenofovir-exposed rats. Didanosine did not elicit renal effects but, unlike tenofovir, depleted mtDNA in liver (by 52%). CONCLUSIONS: Tenofovir DF induces an organ-specific nephrotoxicity with mtDNA depletion and dysfunction of mtDNA-encoded respiratory chain subunits. The data do not support nephrotoxicity of didanosine.
Assuntos
Adenina/análogos & derivados , Fármacos Anti-HIV/toxicidade , DNA Mitocondrial/efeitos dos fármacos , Túbulos Renais Proximais/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Doenças Mitocondriais/induzido quimicamente , Organofosfonatos/toxicidade , Inibidores da Transcriptase Reversa/toxicidade , Adenina/toxicidade , Animais , Didanosina/toxicidade , Transporte de Elétrons/efeitos dos fármacos , Complexo IV da Cadeia de Transporte de Elétrons/efeitos dos fármacos , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Túbulos Renais Proximais/ultraestrutura , Masculino , Microscopia Eletrônica de Transmissão , Mitocôndrias/ultraestrutura , Doenças Mitocondriais/patologia , NADH Desidrogenase/efeitos dos fármacos , NADH Desidrogenase/metabolismo , Ratos , Ratos Sprague-Dawley , TenofovirRESUMO
BACKGROUND: The aim of this study was to determine the effects of HIV type-1 (HIV-1) infection and antiretroviral therapy (ART) on placental mitochondria. METHODS: HIV-1-infected pregnant women and HIV-1-uninfected controls were enrolled prospectively. Placental mitochondrial DNA (mtDNA) copy numbers were determined by quantitative PCR, subunits II and IV of cytochrome c oxidase (COX) were quantified by western blot and mitochondrial ultrastructure was evaluated by electron microscopy. Venous blood lactate was measured in newborns. RESULTS: In total, 45 HIV-1-infected pregnant women on ART and 32 controls were included. Mean +/-sd mtDNA copy numbers were significantly reduced in ART and HIV-1-exposed placentas (240 +/-118 copies/cell) in comparison with controls (686 +/-842 copies/cell; P<0.001). The mean COX II/IV ratio was 48% lower in the investigational group compared with controls (P<0.001). There was no evidence of severe ultrastructural damage within mitochondria of HIV-1-infected ART-exposed placentas. Although lactate levels between newborns did not differ, they were negatively correlated with placental mtDNA levels. There was no clear association between mitochondrial parameters and a particular nucleoside reverse transcriptase inhibitor (NRTI), the number of NRTIs or time of NRTI exposure. CONCLUSIONS: Placental tissue of HIV-1-infected ART-exposed pregnancies shows evidence of mtDNA depletion with secondary respiratory chain compromise. The clinical effects of this finding warrant further investigation.
Assuntos
Fármacos Anti-HIV/efeitos adversos , Infecções por HIV/tratamento farmacológico , HIV-1 , Mitocôndrias/efeitos dos fármacos , Placenta/efeitos dos fármacos , Complicações Infecciosas na Gravidez/virologia , Adulto , Fármacos Anti-HIV/uso terapêutico , Terapia Antirretroviral de Alta Atividade/efeitos adversos , DNA Mitocondrial/análise , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Humanos , Recém-Nascido/sangue , Ácido Láctico/sangue , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Placenta/metabolismo , Placenta/ultraestrutura , Gravidez , Complicações Infecciosas na Gravidez/tratamento farmacológico , Estudos RetrospectivosRESUMO
Fosalvudine tidoxil is a prodrug derived from the nucleoside reverse transcriptase inhibitor 3-deoxy-3-fluorothymidine (FLT; alovudine). FLT effectively inhibits resistant human immunodeficiency virus type 1, but its clinical development was stopped due to bone marrow and liver toxicity. In this study, we examined the long-term in vivo effects of fosalvudine tidoxil on the mitochondrial DNA (mtDNA) contents in rats. Sprague-Dawley rats received fosalvudine tidoxil (15, 40, or 100 mg/kg of body weight/day) by oral gavage during a period of 8 weeks. Didanosine (100 mg/kg/day) was used as a positive control for mitochondrial toxicity. mtDNA levels in liver, gastrocnemius muscle, sciatic nerve, and inguinal fat pad tissues were quantified by real-time PCR. In hepatic mitochondria, fosalvudine tidoxil induced significant mtDNA depletion. At doses of 15, 40, and 100 mg/kg, the mean hepatic mtDNA values were 62, 64, and 47% of control values, respectively. Rats exposed to 100 mg/kg of fosalvudine tidoxil, unlike all other groups, had slightly elevated levels of glutamate pyruvate transaminase in sera. Didanosine induced a loss of mtDNA (to 48% of the control level) similar to that induced by fosalvudine tidoxil. mtDNA levels in skeletal, neural, and adipose tissues in the negative control and treatment groups were similar. Our results suggest that fosalvudine tidoxil induces mitochondrial hepatotoxicity and that this effect warrants scrutiny in clinical trials.