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1.
Int J Infect Dis ; 142: 106989, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38428479

RESUMO

OBJECTIVES: The empirical treatment of infective endocarditis is still debated. The aim of this study was to compare the impact of empirical treatment with antistaphylococcal penicillin (ASP) or cefazolin vs. other treatments in methicillin-susceptible Staphylococcus aureus (MSSA) endocarditis. METHODS: A post hoc analysis of a prospective cohort study of patients hospitalized in a French reference centre with MSSA endocarditis was conducted between 2013 and 2022. The primary outcome was the duration of bacteraemia under treatment. RESULTS: Of the 208 patients included, 101 patients (48.6%) were classified in the reference group (ASP or cefazolin) and 107 (52.4%) in the non-reference group. Empirical treatment with ASP/cefazolin was associated with a shorter duration of bacteraemia compared to other treatments (3.6 d vs. 4.6 d, P = 0.01). This difference was not corrected by the addition of an aminoglycoside (3.6 d vs. 4.7 d, P < 0.01). In multivariate analysis, empirical treatment with ASP/cefazolin was associated with a duration of bacteraemia ≤72 h (P = 0.02), whereas endocarditis on native valves (P = 0.01), and intracardiac abscess were associated with longer duration of bacteraemia (P = 0.01). CONCLUSIONS: Empirical treatment of endocarditis with ASP or Cefazolin is more effective than other treatments in MSSA endocarditis, even when the other treatments are combined with aminoglycosides.


Assuntos
Bacteriemia , Endocardite Bacteriana , Endocardite , Infecções Estafilocócicas , Humanos , Cefazolina/uso terapêutico , Meticilina/farmacologia , Meticilina/uso terapêutico , Estudos Prospectivos , Staphylococcus aureus , Estudos de Coortes , Infecções Estafilocócicas/tratamento farmacológico , Antibacterianos/uso terapêutico , Endocardite Bacteriana/tratamento farmacológico , Endocardite/tratamento farmacológico , Bacteriemia/tratamento farmacológico
2.
PLoS Negl Trop Dis ; 17(4): e0011238, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-37079647

RESUMO

INTRODUCTION: Leprosy reactions (LRs) are inflammatory responses observed in 30%-50% of people with leprosy. First-line treatment is glucocorticoids (GCs), often administered at high doses with prolonged courses, resulting in high morbi-mortality. Methotrexate (MTX) is an immunomodulating agent used to treat inflammatory diseases and has an excellent safety profile and worldwide availability. In this study, we describe the efficacy, GCs-sparing effect and safety of MTX in LRs. METHODS: We conducted a retrospective multicentric study in France consisting of leprosy patients receiving MTX for a reversal reaction (RR) and/or erythema nodosum leprosum (ENL) since 2016. The primary endpoint was the rate of good response (GR) defined as the complete disappearance of inflammatory cutaneous or neurological symptoms without recurrence during MTX treatment. The secondary endpoint was the GCs-sparing effect, safety and clinical relapse after MTX discontinuation. RESULTS: Our study included 13 patients with LRs (8 men, 5 women): 6 had ENL and 7 had RR. All patients had had at least one previous course of GCs and 2 previous treatment lines before starting MTX. Overall, 8/13 (61.5%) patients had GR, allowing for GCs-sparing and even GCs withdrawal in 6/11 (54.5%). No severe adverse effects were observed. Relapse after MTX discontinuation was substantial (42%): the median relapse time was 5.5 months (range 3-14) after stopping treatment. CONCLUSION: MTX seems to be an effective alternative treatment in LRs, allowing for GCs-sparing with a good safety profile. Furthermore, early introduction during LRs may lead to a better therapeutic response. However, its efficacy seems to suggest prolonged therapy to prevent recurrence.


Assuntos
Eritema Nodoso , Hanseníase Virchowiana , Hanseníase , Masculino , Humanos , Feminino , Metotrexato/uso terapêutico , Estudos Retrospectivos , Eritema Nodoso/tratamento farmacológico , Eritema Nodoso/complicações , Hanseníase/tratamento farmacológico , Hanseníase Virchowiana/complicações , Glucocorticoides , Recidiva
3.
Clin Microbiol Infect ; 29(4): 543.e5-543.e9, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36586513

RESUMO

OBJECTIVES: Our aim was to compare the clinical and virological outcomes in Omicron BA.1- and BA.2-infected patients who received sotrovimab with those in patients who received nirmatrelvir for the prevention of severe COVID-19. METHODS: In this multi-centric, prospective ANRS 0003S CoCoPrev cohort study, patients at a high risk of progression of mild-to-moderate BA.1 or BA.2 COVID-19 who received sotrovimab or nirmatrelvir were included. The proportion of patients with progression to severe COVID-19, time between the start of treatment to negative PCR conversion, SARS-CoV-2 viral decay, and characterization of resistance variants were determined. A multi-variable Cox proportional hazard model was used to determine the time to negative PCR conversion and a mixed-effect model for the dynamics of viral decay. RESULTS: Amongst 255 included patients, 199 (80%) received ≥3 vaccine doses, 195 (76%) received sotrovimab, and 60 (24%) received nirmatrelvir. On day 28, new COVID-19-related hospitalization occurred in 4 of 193 (2%; 95% CI, 1-5%) sotrovimab-treated patients and 0 of 55 nirmatrelvir-treated patients (p 0.24). One out of the 55 nirmatrelvir-treated patients died (2%; 95% CI, 0-10%). The median time to negative PCR conversion was 11.5 days (95% CI, 10.5-13) in the sotrovimab-treated patients vs. 4 days (95% CI, 4-9) in the nirmatrelvir-treated patients (p < 0.001). Viral decay was faster in the patients who received nirmatrelvir (p < 0.001). In the multi-variable analysis, nirmatrelvir and nasopharyngeal PCR cycle threshold values were independently associated with faster conversion to negative PCR (hazard ratio, 2.35; 95% CI, 1.56-3.56; p < 0.0001 and hazard ratio, 1.05; 95% CI, 1.01-1.08; p 0.01, respectively). CONCLUSIONS: Early administration of nirmatrelvir in high-risk patients compared with that of sotrovimab was associated with faster viral clearance. This may participate to decrease transmission and prevent viral resistance.


Assuntos
COVID-19 , Humanos , Estudos de Coortes , Estudos Prospectivos , SARS-CoV-2/genética , Reação em Cadeia da Polimerase , Lactamas , Leucina , Nitrilas , Teste para COVID-19
5.
J Infect Dis ; 224(12): 2160-2169, 2021 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-34019653

RESUMO

BACKGROUND: Septic shock remains a major cause of death that can be complicated by long-term impairment in immune function. Among regulatory T (Treg) cells, the tumor necrosis factor receptor 2 positive (TNFR2pos) Treg-cell subset endorses significant immunosuppressive functions in human tumors and a sepsis mouse model but has not been investigated during septic shock in humans. METHODS: We prospectively enrolled patients with septic shock hospitalized in intensive care units (ICU). We performed immunophenotyping and functional tests of CD4+ T cells, Treg cells, and TNFR2pos Treg cells on blood samples collected 1, 4, and 7 days after admission to ICU. RESULTS: We investigated 10 patients with septic shock compared to 10 healthy controls. Although the proportions of circulating Treg cells and TNFR2pos Treg-cell subsets were not increased, their CTLA4 expression and suppressive functions in vitro were increased at 4 days of septic shock. Peripheral blood mononuclear cells from healthy donors cultured with serum from septic shock patients had increased CTLA4 expression in TNFR2pos Treg cells compared to TNFR2neg Treg cells. CONCLUSIONS: In patients with septic shock, CTLA4 expression and suppressive function were increased in circulating TNFR2pos Treg cells. We identify TNFR2pos Treg cells as a potential attractive target for therapeutic intervention.


Assuntos
Linfócitos T CD4-Positivos/metabolismo , Antígeno CTLA-4/metabolismo , Receptores Tipo II do Fator de Necrose Tumoral/metabolismo , Sepse/metabolismo , Choque Séptico/imunologia , Linfócitos T Reguladores/imunologia , Animais , Humanos , Terapia de Imunossupressão , Leucócitos Mononucleares , Camundongos
6.
Clin Microbiol Infect ; 27(7): 1015-1021, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32950711

RESUMO

OBJECTIVES: Current guidelines recommend cefazolin as an alternative to antistaphylococcal penicillins (ASPs) in methicillin-susceptible Staphylococcus aureus (MSSA) infective endocarditis despite the lack of comparative study. The objective of this study was to evaluate the comparative outcomes of cefazolin vs. ASPs in MSSA infective endocarditis. METHODS: This was a retrospective analysis of an observational multicentre cohort study using prospectively collected data from patients with MSSA endocarditis confirmed by endocarditis team and treated either with cefazolin or ASPs between July 2013 and December 2018. Patients were excluded if they received both treatments. The primary outcome was 90-day all-cause mortality. RESULTS: Of 210 patients included, 53 patients (25.2%) received cefazolin and 157 (74.8%) received ASPs. The overall 90-day mortality rate was 27.6% (58/210 patients), 24.5% (13/53) in the cefazolin group vs. 28.7% (45/157) in the ASP group (p 0.561). Premature antimicrobial discontinuation due to adverse events occurred less frequently with cefazolin than with ASPs (0/53 vs. 13/157 patients; p 0.042). In multivariate analysis, there was no difference in 90-day mortality between cefazolin and ASPs (adjusted odds ratio (aOR), 1.2; 95% confidence interval (CI), 0.49-2.91; p 0.681), while age (aOR, 1.06; 95% CI, 1.03-1.09; p < 0.001), Charlson comorbidity index (aOR, 1.18; 95% CI, 1.02-1.36 p 0.023), cerebral embolism (aOR, 2.83; 95% CI, 1.33-6.14; p 0.007) and intensive care unit admission (aOR, 4.16; 95% CI, 1.89-9.59; p 0.001) were factors significantly associated with higher mortality. CONCLUSIONS: Cefazolin seems to be a possible alternative to ASPs in MSSA endocarditis. More studies are needed to confirm these results and determine which treatment should be recommended as first-line therapy.


Assuntos
Antibacterianos/uso terapêutico , Cefazolina/uso terapêutico , Endocardite Bacteriana/tratamento farmacológico , Penicilinas/uso terapêutico , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Idoso , Endocardite Bacteriana/microbiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Estudos Retrospectivos , Infecções Estafilocócicas/microbiologia , Resultado do Tratamento
7.
J Infect Dis ; 222(7): 1222-1234, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32697326

RESUMO

Sepsis causes inflammation-induced immunosuppression with lymphopenia and alterations of CD4+ T-cell functions that renders the host prone to secondary infections. Whether and how regulatory T cells (Treg) are involved in this postseptic immunosuppression is unknown. We observed in vivo that early activation of Treg during Staphylococcus aureus sepsis induces CD4+ T-cell impairment and increases susceptibility to secondary pneumonia. The tumor necrosis factor receptor 2 positive (TNFR2pos) Treg subset endorsed the majority of effector immunosuppressive functions, and TNRF2 was particularly associated with activation of genes involved in cell cycle and replication in Treg, probably explaining their maintenance. Blocking or deleting TNFR2 during sepsis decreased the susceptibility to secondary infection. In humans, our data paralleled those in mice; the expression of CTLA-4 was dramatically increased in TNFR2pos Treg after culture in vitro with S. aureus. Our findings describe in vivo mechanisms underlying sepsis-induced immunosuppression and identify TNFR2pos Treg as targets for therapeutic intervention.


Assuntos
Antígenos CD4/metabolismo , Linfócitos T CD4-Positivos/metabolismo , Receptores Tipo II do Fator de Necrose Tumoral/metabolismo , Sepse/metabolismo , Linfócitos T Reguladores/metabolismo , Animais , Linfócitos T CD4-Positivos/citologia , Células Cultivadas , Feminino , Humanos , Terapia de Imunossupressão , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores Tipo II do Fator de Necrose Tumoral/deficiência , Sepse/microbiologia , Staphylococcus aureus , Linfócitos T Reguladores/citologia
9.
J Antimicrob Chemother ; 74(4): 1021-1027, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30689937

RESUMO

OBJECTIVES: Since 2016, French guidelines have recommended the single-tablet regimen of tenofovir disoproxil fumarate (TDF)/emtricitabine (FTC)/rilpivirine (RPV) as HIV post-exposure prophylaxis (PEP), but few data support this usage. We evaluated the tolerability, treatment completion and occurrence of HIV seroconversion associated with this combination in occupational and non-occupational PEP. PATIENTS AND METHODS: We conducted an observational, prospective, multicentre, open-label, non-randomized study in five French HIV centres. Adults requiring PEP according to national French guidelines were prescribed TDF/FTC/RPV one pill once a day for 28 days. Clinical and biological tolerability was assessed at week 4; occurrence of HIV seroconversion was evaluated after week 16. RESULTS: From March 2016 to March 2017, 163 courses of PEP were prescribed for 150 sexual exposures (44% heterosexual and 56% MSM) and 13 non-sexual exposures. Five participants stopped PEP after a few days because the source person was HIV uninfected. Of the remaining 158 individuals, 15 (9.5%) were lost to follow-up at week 4, 7 (4.4%) prematurely discontinued PEP [patient's decision/non-adherence (n = 3) or adverse events (gastrointestinal intolerance n = 3, fatigue n = 1)] and 136 (86.1%) completed the 28 day treatment. Overall, 69.6% of participants declared at least one adverse event, mostly of mild to moderate intensity and no serious adverse events or hepatic or renal toxicity occurred. No HIV seroconversion occurred at week 16. CONCLUSIONS: The low rate of premature treatment interruption, the good tolerability and the absence of documented HIV seroconversion support the current French guidelines of a 28 day course of TDF/FTC/RPV for sexual and non-sexual PEP.


Assuntos
Infecções por HIV/prevenção & controle , Infecções por HIV/virologia , HIV-1/efeitos dos fármacos , Profilaxia Pós-Exposição , Adulto , Idoso , Fármacos Anti-HIV/administração & dosagem , Terapia Antirretroviral de Alta Atividade , Emtricitabina/administração & dosagem , Feminino , Humanos , Masculino , Adesão à Medicação , Pessoa de Meia-Idade , Estudos Prospectivos , Rilpivirina/administração & dosagem , Tenofovir/administração & dosagem , Resultado do Tratamento , Carga Viral
11.
AIDS ; 28(8): 1181-91, 2014 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-24901259

RESUMO

OBJECTIVE: The Mortalité 2010 survey aimed at describing the causes of death among HIV-infected patients in France in 2010 and their evolution since 2000. DESIGN AND METHODS: A national sample of clinical sites, providing HIV care and treatment, notified and documented deaths using a standardized questionnaire. RESULTS: The 90 participating wards notified 728 deaths. Median age at death was 50 years (interquartile range 45-58) and 75% were men. The main underlying causes of death were AIDS-related (25% in 2010 vs. 36% in 2005 and 47% in 2000), non-AIDS non-viral hepatitis-related malignancy (22 vs. 17 and 11%), liver-related (11 vs. 15 and 13%), cardiovascular diseases (10 vs. 8 and 7%) and non-AIDS-related infections (9 vs. 4 and 7%). Malignancies (AIDS and non-AIDS-related) accounted for a third of all causes of death. AIDS accounted for 33% of all causes of death among patients mono-infected with HIV vs. only 13% among those co-infected with hepatitis B virus or hepatitis C virus. CONCLUSION: In 2010, 25% of the causes of death among HIV-infected patients remained AIDS-related. Improved screening and earlier HIV treatment should lead to a smaller proportion of deaths due to AIDS. The majority of patients died of various causes, whereas their HIV infection was well controlled under treatment. Improving case management of HIV-infected patients should include a multidisciplinary approach (prevention, screening, treatment), especially in oncology. Smoking cessation should be a priority goal.


Assuntos
Causas de Morte/tendências , Infecções por HIV/epidemiologia , Síndrome da Imunodeficiência Adquirida/mortalidade , Adulto , Feminino , França/epidemiologia , Hepatite B/epidemiologia , Hepatite C/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco
12.
Mov Disord ; 26(11): 2123-6, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21714011

RESUMO

BACKGROUND: The X-linked McLeod syndrome belongs to the group of neuroacanthocytosis syndromes and has a Huntington-disease-like phenotype with a choreatic movement disorder, cognitive alterations, and psychiatric symptoms. Another neuroacanthocytosis syndrome, the autosomal recessive chorea-acanthocytosis, has a similar presentation, but distinct clinical features, believed to be characteristic, such as tongue protrusion dystonia, feeding dystonia, and rubber-man-like appearance. METHODS: This work comprised a case series of 3 patients with McLeod syndrome. RESULTS: The 3 patients with McLeod syndrome developed severe feeding dystonia and tongue protrusion as well as rubber-man-like appearance in 1 patient during the course of the disease. CONCLUSION: These observations indicate that there is an extended phenotypic overlap between McLeod syndrome and chorea-acanthocytosis.


Assuntos
Distonia/etiologia , Comportamento Alimentar/fisiologia , Doenças do Sistema Nervoso/complicações , Neuroacantocitose/complicações , Idoso , Humanos , Masculino , Pessoa de Meia-Idade , Doenças do Sistema Nervoso/genética , Neuroacantocitose/genética
14.
Obes Surg ; 20(1): 126-9, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19763705

RESUMO

Hypoglycemia is rare after a gastric bypass and can be taken for a dumping syndrome. There is no report in the literature of the contribution of continuous glucose monitoring to the diagnosis of hypoglycemia in these circumstances. The present case report shows that continuous glucose monitoring can be a useful tool for the diagnosis and the management of such episodes. Continuous glucose monitoring revealed hypoglycemic episodes in free living circumstances that were not present during 72-h fasting. These episodes followed wide hyperglycemic swings. No such episode resumed over 8 months after specific dietary advices and treatment by 50 mg TID of acarbose. Because hypoglycemia can be difficult to diagnose from dumping syndrome, continuous glucose monitoring is a very useful tool revealing the episodes in free living circumstances and can be used to monitor the treatment success.


Assuntos
Diabetes Mellitus Tipo 2/epidemiologia , Hipoglicemia/diagnóstico , Monitorização Fisiológica/métodos , Obesidade Mórbida/epidemiologia , Adulto , Comorbidade , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Feminino , Derivação Gástrica , Humanos , Obesidade Mórbida/cirurgia
15.
Arch Biochem Biophys ; 465(1): 282-92, 2007 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-17603005

RESUMO

Biogenesis of iron-sulfur (Fe-S) clusters in mammals involves a complex mitochondrial machinery that provides inorganic sulfide and iron for their assembly and insertion into apo-proteins. Mechanisms of Fe-S cluster assembly are just being unraveled, and regulation of the genes of this machinery remains unknown. In this study, we report that expression of two essential components of the Fe-S machinery, the cysteine desulfurase Nfs1 and its scaffold protein partner IscU, is down-regulated at both mRNA and protein levels when murine macrophages are physiologically stimulated with IFN-gamma and LPS. Regulation did not rely on cluster disassembly or NO production because exposure of cells to exogenous sources of NO did not alter Nfs1 expression, while it converted cytosolic Fe-S aconitase into its apo-form and because macrophages from NOS2 deficient mice displayed Nfs1 down-regulation. While IFN-gamma alone induced Nfs1 protein instability, LPS triggered a delayed decline of Nfs1, rather involving transcriptional events or mRNA instability. Also, the expression of IscU was down-regulated in IFN-gamma- and/or LPS-stimulated macrophages independently of NO, pointing to a general mechanism for marshalling the regulation of the Fe-S cluster assembly machinery in macrophages exposed to inflammatory stimuli.


Assuntos
Liases de Carbono-Enxofre/metabolismo , Interferon gama/administração & dosagem , Proteínas Ferro-Enxofre/metabolismo , Lipopolissacarídeos/administração & dosagem , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Animais , Liases de Carbono-Enxofre/administração & dosagem , Células Cultivadas , Relação Dose-Resposta a Droga , Feminino , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/fisiologia , Camundongos , Camundongos Endogâmicos C57BL
16.
J Nat Prod ; 70(4): 510-4, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17291039

RESUMO

The effects and the mode of action of hypericin (1) were studied, in the dark, on the action potential (AP) and the L-type Ca2+ channel of frog atrial heart muscle, using intracellular microelectrode and patch-clamp techniques, respectively. In the presence of Ca2+ in Ringer solution, hypericin (1 to 4 microM) did not markedly modify the AP. Total replacement of Ca2+ by Sr2+ in the solution (Ringer Sr2+) revealed that hypericin (4 microM) prolonged the AP duration (APD). Hypericin dose-dependently increased the magnitude of the Sr2+current, which develops through L-type Ca2+ channels in the Ringer solution containing tetrodotoxin (0.7 microM) and tetraethylammonium (10 mM), but did not modify the kinetics of activation and inactivation. This revealed that hypericin increased L-type Ca2+ channel conductance, which accounted for the APD lengthening. The hypericin-induced APD lengthening recorded in the Ringer Sr2+ was not prevented by (i) a blockade of alpha- and beta-adrenoceptors by yohimbine (1 microM), urapidil (1 microM), and propanolol (50 microM), respectively, and (ii) PKC blockade by staurosporine (1 microM). The hypericin-induced APD lengthening recorded in the Ringer Sr2+ was prevented by blocking soluble guanylate cyclase (sGC) activity by 1H-[1,2,4]-oxadiazolo[4,3-a]quinoxalin-1-one (13 microM), which mimicked the effects of hypericin. Hypericin decreased the cellular cGMP level by 69% in atrial myocytes. The compound also decreased the cellular cGMP level by inhibiting sGC, thus cancelling the nucleotide inhibitory effect on the cardiac L-type Ca2+ channel.


Assuntos
Canais de Cálcio Tipo L/efeitos dos fármacos , Miócitos Cardíacos/efeitos dos fármacos , Perileno/análogos & derivados , Potenciais de Ação/efeitos dos fármacos , Animais , Antracenos , GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Guanilato Ciclase/antagonistas & inibidores , Coração/efeitos dos fármacos , Estrutura Molecular , Óxido Nítrico Sintase Tipo II/metabolismo , Oxidiazóis/farmacologia , Perileno/química , Perileno/farmacologia , Fosfoproteínas Fosfatases/metabolismo , Ranidae , Receptores Citoplasmáticos e Nucleares/antagonistas & inibidores , Guanilil Ciclase Solúvel
17.
J Biol Chem ; 281(35): 25398-406, 2006 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-16787928

RESUMO

In prokaryotes and yeast, the general mechanism of biogenesis of iron-sulfur (Fe-S) clusters involves activities of several proteins among which IscS and Nfs1p provide, through cysteine desulfuration, elemental sulfide for Fe-S core formation. Although these proteins have been well characterized, the role of their mammalian homolog in Fe-S cluster biogenesis has never been evaluated. We report here the first functional study that implicates the putative cysteine desulfurase m-Nfs1 in the biogenesis of both mitochondrial and cytosolic mammalian Fe-S proteins. Depletion of m-Nfs1 in cultured fibroblasts through small interfering RNA-based gene silencing significantly inhibited the activities of mitochondrial NADH-ubiquinone oxidoreductase (complex I) and succinate-ubiquinone oxidoreductase (complex II) of the respiratory chain, as well as aconitase of the Krebs cycle, with no alteration in their protein levels. Activity of cytosolic xanthine oxidase, which holds a [2Fe-2S] cluster, was also specifically reduced, and iron-regulatory protein-1 was converted from its [4Fe-4S] aconitase form to its apo- or RNA-binding form. Reduction of Fe-S enzyme activities occurred earlier and more markedly in the cytosol than in mitochondria, suggesting that there is a mechanism that primarily dedicates m-Nfs1 to the biogenesis of mitochondrial Fe-S clusters in order to maintain cell survival. Finally, depletion of m-Nfs1, which conferred on apo-IRP-1 a high affinity for ferritin mRNA, was associated with the down-regulation of the iron storage protein ferritin.


Assuntos
Liases de Carbono-Enxofre/fisiologia , Citosol/metabolismo , Proteínas Ferro-Enxofre/química , Mitocôndrias/metabolismo , Interferência de RNA , Animais , Liases de Carbono-Enxofre/química , Liases de Carbono-Enxofre/genética , Regulação para Baixo , Complexo I de Transporte de Elétrons/química , Complexo II de Transporte de Elétrons/química , Ferritinas/química , Camundongos , Mitocôndrias/enzimologia , Células NIH 3T3 , Xantina Oxidase/química
18.
J Biol Chem ; 277(34): 31220-7, 2002 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-12039960

RESUMO

Iron regulatory proteins (IRPs) control iron metabolism by specifically interacting with iron-responsive elements (IREs) on mRNAs. Nitric oxide (NO) converts IRP-1 from a [4Fe-4S] aconitase to a trans-regulatory protein through Fe-S cluster disassembly. Here, we have focused on the fate of IRE binding IRP1 from murine macrophages when NO flux stops. We show that virtually all IRP-1 molecules from NO-producing cells dissociated from IRE and recovered aconitase activity after re-assembling a [4Fe-4S] cluster in vitro. The reverse change in IRP-1 activities also occurred in intact cells no longer exposed to NO and did not require de novo protein synthesis. Likewise, inhibition of mitochondrial aconitase via NO-induced Fe-S cluster disassembly was also reversed independently of protein translation after NO removal. Our results provide the first evidence of Fe-S cluster repair of NO-modified aconitases in mammalian cells. Moreover, we show that reverse change in IRP-1 activities and repair of mitochondrial aconitase activity depended on energized mitochondria. Finally, we demonstrate that IRP-1 activation by NO was accompanied by both a drastic decrease in ferritin levels and an increase in transferrin receptor mRNA levels. However, although ferritin expression was recovered upon IRP-1-IRE dissociation, expression of transferrin receptor mRNA continued to rise for several hours after stopping NO flux.


Assuntos
Aconitato Hidratase/metabolismo , Trifosfato de Adenosina/metabolismo , Proteínas Ferro-Enxofre/metabolismo , Mitocôndrias/metabolismo , Óxido Nítrico/metabolismo , Proteínas de Ligação a RNA/metabolismo , Animais , Linhagem Celular , Cicloeximida/farmacologia , Ferritinas/metabolismo , Proteína 1 Reguladora do Ferro , Proteínas Reguladoras de Ferro , Macrófagos/metabolismo , Camundongos , RNA Mensageiro/análise , Receptores da Transferrina/genética
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