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1.
Int J Infect Dis ; 142: 106989, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38428479

RESUMEN

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.


Asunto(s)
Bacteriemia , Endocarditis Bacteriana , Endocarditis , Infecciones Estafilocócicas , Humanos , Cefazolina/uso terapéutico , Meticilina/farmacología , Meticilina/uso terapéutico , Estudios Prospectivos , Staphylococcus aureus , Estudios de Cohortes , Infecciones Estafilocócicas/tratamiento farmacológico , Antibacterianos/uso terapéutico , Endocarditis Bacteriana/tratamiento farmacológico , Endocarditis/tratamiento farmacológico , Bacteriemia/tratamiento farmacológico
2.
PLoS Negl Trop Dis ; 17(4): e0011238, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-37079647

RESUMEN

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.


Asunto(s)
Eritema Nudoso , Lepra Lepromatosa , Lepra , Masculino , Humanos , Femenino , Metotrexato/uso terapéutico , Estudios Retrospectivos , Eritema Nudoso/tratamiento farmacológico , Eritema Nudoso/complicaciones , Lepra/tratamiento farmacológico , Lepra Lepromatosa/complicaciones , Glucocorticoides , Recurrencia
3.
Clin Microbiol Infect ; 29(4): 543.e5-543.e9, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36586513

RESUMEN

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.


Asunto(s)
COVID-19 , Humanos , Estudios de Cohortes , Estudios Prospectivos , SARS-CoV-2/genética , Reacción en Cadena de la Polimerasa , Lactamas , Leucina , Nitrilos , Prueba de COVID-19
5.
J Infect Dis ; 224(12): 2160-2169, 2021 12 15.
Artículo en Inglés | MEDLINE | ID: mdl-34019653

RESUMEN

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.


Asunto(s)
Linfocitos T CD4-Positivos/metabolismo , Antígeno CTLA-4/metabolismo , Receptores Tipo II del Factor de Necrosis Tumoral/metabolismo , Sepsis/metabolismo , Choque Séptico/inmunología , Linfocitos T Reguladores/inmunología , Animales , Humanos , Terapia de Inmunosupresión , Leucocitos Mononucleares , Ratones
6.
Clin Microbiol Infect ; 27(7): 1015-1021, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32950711

RESUMEN

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.


Asunto(s)
Antibacterianos/uso terapéutico , Cefazolina/uso terapéutico , Endocarditis Bacteriana/tratamiento farmacológico , Penicilinas/uso terapéutico , Infecciones Estafilocócicas/tratamiento farmacológico , Staphylococcus aureus/efectos de los fármacos , Anciano , Endocarditis Bacteriana/microbiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Estudios Retrospectivos , Infecciones Estafilocócicas/microbiología , Resultado del Tratamiento
7.
J Infect Dis ; 222(7): 1222-1234, 2020 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-32697326

RESUMEN

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.


Asunto(s)
Antígenos CD4/metabolismo , Linfocitos T CD4-Positivos/metabolismo , Receptores Tipo II del Factor de Necrosis Tumoral/metabolismo , Sepsis/metabolismo , Linfocitos T Reguladores/metabolismo , Animales , Linfocitos T CD4-Positivos/citología , Células Cultivadas , Femenino , Humanos , Terapia de Inmunosupresión , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores Tipo II del Factor de Necrosis Tumoral/deficiencia , Sepsis/microbiología , Staphylococcus aureus , Linfocitos T Reguladores/citología
9.
J Antimicrob Chemother ; 74(4): 1021-1027, 2019 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-30689937

RESUMEN

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.


Asunto(s)
Infecciones por VIH/prevención & control , Infecciones por VIH/virología , VIH-1/efectos de los fármacos , Profilaxis Posexposición , Adulto , Anciano , Fármacos Anti-VIH/administración & dosificación , Terapia Antirretroviral Altamente Activa , Emtricitabina/administración & dosificación , Femenino , Humanos , Masculino , Cumplimiento de la Medicación , Persona de Mediana Edad , Estudios Prospectivos , Rilpivirina/administración & dosificación , Tenofovir/administración & dosificación , Resultado del Tratamiento , Carga Viral
11.
AIDS ; 28(8): 1181-91, 2014 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-24901259

RESUMEN

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.


Asunto(s)
Causas de Muerte/tendencias , Infecciones por VIH/epidemiología , Síndrome de Inmunodeficiencia Adquirida/mortalidad , Adulto , Femenino , Francia/epidemiología , Hepatitis B/epidemiología , Hepatitis C/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo
12.
Mov Disord ; 26(11): 2123-6, 2011 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-21714011

RESUMEN

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.


Asunto(s)
Distonía/etiología , Conducta Alimentaria/fisiología , Enfermedades del Sistema Nervioso/complicaciones , Neuroacantocitosis/complicaciones , Anciano , Humanos , Masculino , Persona de Mediana Edad , Enfermedades del Sistema Nervioso/genética , Neuroacantocitosis/genética
14.
Obes Surg ; 20(1): 126-9, 2010 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19763705

RESUMEN

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.


Asunto(s)
Diabetes Mellitus Tipo 2/epidemiología , Hipoglucemia/diagnóstico , Monitoreo Fisiológico/métodos , Obesidad Mórbida/epidemiología , Adulto , Comorbilidad , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Femenino , Derivación Gástrica , Humanos , Obesidad Mórbida/cirugía
15.
Arch Biochem Biophys ; 465(1): 282-92, 2007 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-17603005

RESUMEN

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.


Asunto(s)
Liasas de Carbono-Azufre/metabolismo , Interferón gamma/administración & dosificación , Proteínas Hierro-Azufre/metabolismo , Lipopolisacáridos/administración & dosificación , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Animales , Liasas de Carbono-Azufre/administración & dosificación , Células Cultivadas , Relación Dosis-Respuesta a Droga , Femenino , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Regulación Enzimológica de la Expresión Génica/fisiología , Ratones , Ratones Endogámicos C57BL
16.
J Nat Prod ; 70(4): 510-4, 2007 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-17291039

RESUMEN

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.


Asunto(s)
Canales de Calcio Tipo L/efectos de los fármacos , Miocitos Cardíacos/efectos de los fármacos , Perileno/análogos & derivados , Potenciales de Acción/efectos de los fármacos , Animales , Antracenos , GMP Cíclico/metabolismo , Relación Dosis-Respuesta a Droga , Guanilato Ciclasa/antagonistas & inhibidores , Corazón/efectos de los fármacos , Estructura Molecular , Óxido Nítrico Sintasa de Tipo II/metabolismo , Oxadiazoles/farmacología , Perileno/química , Perileno/farmacología , Fosfoproteínas Fosfatasas/metabolismo , Ranidae , Receptores Citoplasmáticos y Nucleares/antagonistas & inhibidores , Guanilil Ciclasa Soluble
17.
J Biol Chem ; 281(35): 25398-406, 2006 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-16787928

RESUMEN

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.


Asunto(s)
Liasas de Carbono-Azufre/fisiología , Citosol/metabolismo , Proteínas Hierro-Azufre/química , Mitocondrias/metabolismo , Interferencia de ARN , Animales , Liasas de Carbono-Azufre/química , Liasas de Carbono-Azufre/genética , Regulación hacia Abajo , Complejo I de Transporte de Electrón/química , Complejo II de Transporte de Electrones/química , Ferritinas/química , Ratones , Mitocondrias/enzimología , Células 3T3 NIH , Xantina Oxidasa/química
18.
J Biol Chem ; 277(34): 31220-7, 2002 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-12039960

RESUMEN

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.


Asunto(s)
Aconitato Hidratasa/metabolismo , Adenosina Trifosfato/metabolismo , Proteínas Hierro-Azufre/metabolismo , Mitocondrias/metabolismo , Óxido Nítrico/metabolismo , Proteínas de Unión al ARN/metabolismo , Animales , Línea Celular , Cicloheximida/farmacología , Ferritinas/metabolismo , Proteína 1 Reguladora de Hierro , Proteínas Reguladoras del Hierro , Macrófagos/metabolismo , Ratones , ARN Mensajero/análisis , Receptores de Transferrina/genética
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