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INTRODUCTION: Protein nutrition disorder in alkaptonuria (AKU), resulting in increased homogentisic acid (HGA) before nitisinone therapy and increased tyrosine (TYR) during nitisinone therapy, may benefit from dietetic intervention. The aim of this study was to characterise the diet and their effects prospectively in those who received formal dietetic intervention in the nitisinone-receiving National Alkaptonuria Centre (NAC) patients with those who did not in no-nitisinone Suitability of Nitisinone in Alkaptonuria 2 (SN2 N-) and nitisinone-treated SN2 (SN2 N+) randomised study groups. PATIENTS AND METHODS: A total of 63, 69, and 69 AKU patients from the NAC, SN2 N-, and SN2 N+ were studied for anthropometric (weight, BMI), body composition (including muscle mass, %body fat, hand grip strength), chemical characteristics (serum TYR, serum phenylalanine, urine urea or uUREA, and urine creatinine or uCREAT), and corneal keratopathy. Nitisinone 2 mg and 10 mg were employed in the NAC and SN2 N+ groups, respectively. Dieticians managed protein intake in the NAC, while the SN2 N- and SN2 N+ groups only received advice on self-directed protein restriction during four years of study duration. RESULTS: uUREA decreased in the NAC, SN2 N-, and SN2 N+ groups, showing that protein restriction was achieved in these groups. Body weight and BMI increased in the NAC and SN2 N+ groups. uCREAT decreased significantly in SN2 N- and SN2 N+ compared with the NAC over four years of study. Corneal keratopathy was less frequent in the NAC than in the SN2 N+ group. Active dietetic intervention in NAC stabilised lean body mass (muscle mass, hand grip strength) despite a decrease in uUREA and uCREAT, as well as sTYR. CONCLUSION: Ongoing dietetic intervention prevented loss of lean body mass despite protein restriction and moderated serum tyrosine increase, leading to less prevalent corneal keratopathy. Protein restriction risks fat mass gain.
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Alcaptonuria , Composición Corporal , Ciclohexanonas , Nitrobenzoatos , Humanos , Masculino , Femenino , Persona de Mediana Edad , Composición Corporal/efectos de los fármacos , Anciano , Tirosina/sangre , Tirosina/análogos & derivados , Adulto , Estudios Prospectivos , Índice de Masa Corporal , Estado Nutricional , Fenilalanina/sangre , Antropometría , Ácido Homogentísico/orina , Fuerza de la ManoRESUMEN
Background: Increased homogentisic acid (HGA) in alkaptonuria (AKU) causes severe arthritis. Nitisinone reduces the production of HGA, but whether it also decreases arthroplasty was examined in 237 AKU patients. Patients and methods: Patients attending the United Kingdom National Alkaptonuria Centre (NAC) and the Suitability of Nitisinone in Alkaptonuria 2 (SONIA 2) study were studied. Assessments included questionnaires eliciting details of arthroplasty. Nitisinone was administered from baseline, 2 mg in the NAC and 10 mg in SONIA 2. In SONIA 2, subgroups consisted of those with baseline arthroplasty on and not on nitisinone (BR + N+, BR + N-), as well as those without baseline arthroplasty on and not on nitisinone (BR-N+, BR-N-). Results: In the SONIA2 subgroups, new joint replacement (JR) probabilities after baseline were significantly different (BR + N+, BR + N-, BR-N+, BR-N-) (χ2 = 23.3, p < 0.001); mean (SD) was 3.8 (0.1) years in BR-N-, 3.7 (0.1) years in BR-N+, 3.4 (0.3) years in BR + N-, and 3.0 (0.3) years in BR + N+. Further, the BR + N- showed more JR than the BR-N- subgroup (p < 0.01), while BR + N+ similarly showed more JR than the BR-N+ subgroup (p < 0.001).In the NAC, the BR- group had a mean age of 51.6 (7.0) years at baseline but 57.7 (8.7) years at final follow up during nitisinone therapy and showed only 7 incident JR. The BR+ group had an age at baseline of 57.4 (8.5) years and had undergone 94 JRs at baseline. Conclusion: The incidence of arthroplasty was earlier and more frequent after the first JR and was not affected by nitisinone.
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Altered activity of specific enzymes in phenylalanine-tyrosine (phe-tyr) metabolism results in incomplete breakdown of various metabolite substrates in this pathway. Increased biofluid concentration and tissue accumulation of the phe-tyr pathway metabolite homogentisic acid (HGA) is central to pathophysiology in the inherited disorder alkaptonuria (AKU). Accumulation of metabolites upstream of HGA, including tyrosine, occurs in patients on nitisinone, a licenced drug for AKU and hereditary tyrosinaemia type 1, which inhibits the enzyme responsible for HGA production. The aim of this study was to investigate the phe-tyr metabolite content of key biofluids and tissues in AKU mice on and off nitisinone to gain new insights into the biodistribution of metabolites in these altered metabolic states. The data show for the first time that HGA is present in bile in AKU (mean [±SD] = 1003[±410] µmol/L; nitisinone-treated AKU mean [±SD] = 45[±23] µmol/L). Biliary tyrosine, 3(4-hydroxyphenyl)pyruvic acid (HPPA) and 3(4-hydroxyphenyl)lactic acid (HPLA) are also increased on nitisinone. Urine was confirmed as the dominant elimination route of HGA in untreated AKU, but with indication of biliary excretion. These data provide new insights into pathways of phe-tyr metabolite biodistribution and metabolism, showing for the first time that hepatobiliary excretion contributes to the total pool of metabolites in this pathway. Our data suggest that biliary elimination of organic acids and other metabolites may play an underappreciated role in disorders of metabolism. We propose that our finding of approximately 3.8 times greater urinary HGA excretion in AKU mice compared with patients is one reason for the lack of extensive tissue ochronosis in the AKU mouse model.
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Alcaptonuria , Ciclohexanonas , Modelos Animales de Enfermedad , Ácido Homogentísico , Nitrobenzoatos , Alcaptonuria/orina , Alcaptonuria/metabolismo , Animales , Ácido Homogentísico/orina , Ácido Homogentísico/metabolismo , Ratones , Ciclohexanonas/orina , Masculino , Tirosina/metabolismo , Tirosina/orina , Hígado/metabolismo , Fenilalanina/metabolismoRESUMEN
Alkaptonuria is a rare inherited disorder for which there was no disease-modifying treatment. In order to develop a successful approved therapy of AKU multiple barriers had to be overcome. These included activities before the conduct of the study including deciding on the drug therapy, the dose of the drug to be used, clarify the nature of the disease, develop outcome measures likely to yield a positive outcome, have a strategy to ensure appropriate patient participation through identification, build a consortium of investigators, obtain regulatory approval for proposed investigation plan and secure funding. Significant barriers were overcome during the conduct of the multicentre study to ensure harmonisation. Mechanisms were put in place to recruit and retain patients in the study. Barriers to patient access following completion of the study and regulatory approval were resolved.
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Alcaptonuria , Humanos , Alcaptonuria/tratamiento farmacológico , Enfermedades Raras/tratamiento farmacológico , Ciclohexanonas/uso terapéutico , Nitrobenzoatos/uso terapéutico , Ácido Homogentísico , Ensayos Clínicos Controlados Aleatorios como Asunto , Estudios Multicéntricos como AsuntoRESUMEN
Nitisinone (NIT) produces inevitable but varying degree of tyrosinaemia. However, the understanding of the dynamic adaptive relationships within the tyrosine catabolic pathway has not been investigated fully. The objective of the study was to assess the contribution of protein intake, serum NIT (sNIT) and tyrosine pathway metabolites to nitisinone-induced tyrosinaemia in alkaptonuria (AKU). Samples of serum and 24-h urine collected during SONIA 2 (Suitability Of Nitisinone In Alkaptonuria 2) at months 3 (V2), 12 (V3), 24 (V4), 36 (V5) and 48 (V6) were included in these analyses. Homogentisic acid (HGA), tyrosine (TYR), phenylalanine (PHE), hydroxyphenylpyruvate (HPPA), hydroxyphenyllactate (HPLA) and sNIT were analysed at all time-points in serum and urine. Total body water (TBW) metabolites were derived using 60% body weight. 24-h urine and TBW metabolites were summed to obtain combined values. All statistical analyses were post-hoc. 307 serum and 24-h urine sampling points were analysed. Serum TYR from V2 to V6, ranging from 478 to 1983 µmol/L were stratified (number of sampling points in brackets) into groups < 701 (47), 701-900 (105), 901-1100 (96) and > 1100 (59) µmol/L. The majority of sampling points had values greater than 900 µmol/L. sPHE increased with increasing sTYR (p < 0.001). Tyrosine, HPPA and HPLA in serum and TBW all increased with rising sTYR (p < 0.001), while HPLA/TYR ratio decreased (p < 0.0001). During NIT therapy, adaptive response to minimise TYR formation was demonstrated. Decreased conversion of HPPA to HPLA, relative to TYR, seems to be most influential in determining the degree of tyrosinaemia.
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Alcaptonuria , Encefalopatías Metabólicas Innatas , Tirosinemias , Alcaptonuria/tratamiento farmacológico , Ciclohexanonas/uso terapéutico , Ácido Homogentísico , Humanos , Nitrobenzoatos/uso terapéutico , Fenilalanina , Fenilpropionatos , Tirosina/metabolismo , Tirosinemias/tratamiento farmacológicoRESUMEN
BACKGROUND: Adaptations within the phenylalanine (PHE)/tyrosine (TYR) pathway during nitisinone (NIT) are not fully understood. OBJECTIVE: To characterise the temporal changes in metabolic features in NIT-treated patients with alkaptonuria. PATIENTS AND METHODS: Serum (s) and 24-urine (u) homogentisic acid (sHGA, uHGA24), TYR (sTYR, uTYR24), PHE (sPHE, uPHE24), hydroxyphenylpyruvate (sHPPA, uHPPA24), hydroxyphenyllactate (sHPLA, uHPLA24) and sNIT were measured at baseline (V1) and until month 48 (V6) in 69 NIT-treated patients, recommended to reduce protein intake. The 24-h urine urea (uUREA24), creatinine (uCREAT24) and body weight were also measured. Amounts of tyrosine metabolites in total body water (TBW) were derived by multiplying the serum concentrations by 60% body weight, and sum of TBW and urine metabolites resulted in combined values (c). RESULTS: uUREA24 and uCREAT24 decreased between V1 and V6 during NIT, whereas body weight and sNIT increased. Linear regression coefficient between uUREA24 and uCREAT24 was extremely strong (R = 0.84). sPHE, TBWPHE and cPHE24 increased gradually from V1 to V6. A decrease in cTYR24/cPHE24, sTYR/sPHE and TBWTYR/TBWPHE was seen from V2 to V6. Serum, 24-urine and combined TYR, HPPA and HPLA either remained stable or decreased from V2 to V6. DISCUSSION: The gradual increase in PHE suggests adaptation to increasing TYR during NIT therapy. The decrease in protein intake resulted in decreased muscle mass and increased weight gain. CONCLUSION: Progressive adaptation by decreasing PHE conversion to TYR occurs over time during NIT therapy. A low protein diet results in loss of muscle mass but also weight gain suggesting an increase in fat mass.
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BACKGROUND: Although changes in the tyrosine pathway during nitisinone therapy are known, a complete characterization of the induced tyrosinaemia is lacking to improve disease management. PATIENTS AND METHODS: Our research aims were addressed by 24-h blood sampling. 40 patients with alkaptonuria (AKU), treated with 0, 1, 2, 4 and 8 mg nitisinone daily (n = 8), were studied over four weeks. Serum homogentisic acid (sHGA), tyrosine (sTYR), phenylalanine (sPHE), hydroxyphenylpyruvate (sHPPA), hydroxyphenyllactate (sHPLA) and nitisinone (sNIT) were measured at baseline and after four weeks. RESULTS: sNIT showed a clear dose-proportional response. sTYR increased markedly but with less clear-cut dose responses after nitisinone. Fasting and average 24-h (Cav) sTYR responses were similar. Individual patient sTYR 24-h profiles showed significant fluctuations during nitisinone therapy. At week 4, sTYR, sHPPA and sHPPL all showed dose-related increases compared to V0, with the greatest difference between 1 and 8 mg nitisinone seen for HPLA, while there was no change from V0 in sPHE. sHGA decreased to values around the lower limit of quantitation. DISCUSSION: There was sustained tyrosinaemia after four weeks of nitisinone therapy with significant fluctuations over the day in individual patients. Diet and degree of conversion of HPPA to HPLA may determine extent of nitisinone-induced tyrosinaemia. CONCLUSION: A fasting blood sample is recommended to monitor sTYR during nitisinone therapy Adaptations in HPPA metabolites as well as the inhibition of tyrosine aminotransferase could be contributing factors generating tyrosinaemia during nitisinone therapy.
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BACKGROUND: Alkaptonuria is a rare genetic disease that leads to structural joint damage and impaired movement function. Previous research indicates that alkaptonuria affects gait, however the detailed mechanisms are unknown. RESEARCH QUESTION: What are the joint-specific gait mechanisms which contribute to impaired gait in alkaptonuria patients? METHODS: The gait of 36 alkaptonuria patients were compared to those of 21 unimpaired controls. The AKU patients were split into three age groups (young 16-29 years, n = 9, middle 30-49 years, n = 16 and old 50 + years, n = 11), and the kinematic and kinetic gait profiles were compared to speed-matched controls using a spm1d two-sample t-test. RESULTS: The young AKU group showed significant differences in the sagittal plane of the knee joint compared to speed-matched controls. The middle group showed deviations in the knee and hip joints. The old group showed significant differences in multiple joints and planes and exhibited gait mechanisms which may be compensation strategies. SIGNIFICANCE: This study is the first to identify and describe joint-specific mechanisms during gait in alkaptonuria patients. Gait deviations were evident even in young AKU patients, including a 16-year-old, much earlier than previously thought. The knee joint is an important focus of future research and potential interventions as deviations were found across all three AKU age groups.
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Alcaptonuria , Adolescente , Adulto , Alcaptonuria/complicaciones , Fenómenos Biomecánicos , Marcha , Articulación de la Cadera , Humanos , Articulación de la Rodilla , Adulto JovenRESUMEN
Two cases of advanced alkaptonuria (AKU) with co-existing osteoporosis are described. Case 1 developed multiple non-vertebral fragility fractures, while Case 2 developed vertebral fragility fractures, both refractory to bisphosphonates. Difficulties in diagnosing osteoporosis in AKU complicated by extensive calcifying and ossifying spondylosis are discussed. Both patients continued to fracture despite nitisinone therapy for metabolic control of AKU, as well as bisphosphonate antiresorptive therapy for osteoporosis. Subsequently the patients were treated with teriparatide 20 µg subcutaneous injections daily for two years, leading to reduction in fractures soon after commencing therapy in both cases. Markers of bone remodelling P1NP and CTX were stimulated. No complications due hypercalcaemia or calcification were encountered in either case. We conclude that teriparatide is an effective adjunct in the treatment of AKU when bisphosphonates prove ineffective.
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AIMS: A large alkaptonuria (AKU) cohort was studied to better characterise the poorly understood phenotype of aortic stenosis of rare disease AKU. METHODS AND RESULTS: Eighty-one patients attended the National Alkaptonuria Centre (NAC) between 2007 and 2020. Nine only attended once. Fifty-one attended more than once and received nitisinone 2 mg daily. Twenty-one attended at least twice without receiving nitisinone. Assessments included questionnaire analysis, standard transthoracic echocardiography, as well as photographs of ochronotic pigment in eyes and ears at baseline when 2 mg nitisinone was commenced, and yearly thereafter. Blood and urine samples were collected for chemical measurement. The prevalence of aortic stenosis and aortic valve replacement were 22.2 and 6.2% in the current group. Aortic maximum velocity (Vmax) was directly related to varying degrees to age (R = 0.58, p < 0.001), systolic blood pressure (R = 0.32, p < 0.05), serum homogentisic acid (sHGA) (R = 0.28, p < 0.05), ochronosis scores (R = 0.72, p < 0.001), and alkaptonuria severity score index (AKUSSI) (R = 0.58, p < 0.001) on linear regression analysis. Age and ochronosis scores were significantly related to Vmax on multiple regression analysis (p < 0.005). Nitisinone decreased sHGA, 24-h urine HGA (uHGA24), ochronosis scores and AKUSSI significantly at all visits post-nitisinone. Nitisinone decreased Vmax change scores at final visit comparison, with a similar pattern at earlier visits. CONCLUSION: Aortic valve disease is highly prevalent in this NAC cohort, and strongly associated with ochronosis and disease severity. Nitisinone decreases ochronosis and had a similar significant effect on Vmax.
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Alcaptonuria/complicaciones , Alcaptonuria/tratamiento farmacológico , Estenosis de la Válvula Aórtica/fisiopatología , Ciclohexanonas/uso terapéutico , Inhibidores Enzimáticos/uso terapéutico , Nitrobenzoatos/uso terapéutico , Fenotipo , Adulto , Anciano , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Índice de Severidad de la EnfermedadRESUMEN
A 34-year old woman with alkaptonuria had an elective pregnancy, during which she collected urine samples over the duration of her pregnancy until parturition. She had been attending the National Alkaptonuria Centre from the age of 31 years and continued to attend after delivery for a further three annual visits. Data from her NAC visits as well as urine samples collected during pregnancy were analysed. Urine CTX-1/urine creatinine, urine αCTX-I/ urine creatinine, urine CTX-II/ urine creatinine, and urine C3M/urine creatinine all showed a rapid increase early in pregnancy, returning to baseline before increasing in late pregnancy, indicating significant remodelling of bone, subchondral bone, cartilage and other organs and connective tissue rich in collagens I, II and III. The pattern of tissue remodelling in AKU pregnancy has been described for the very first time. Further research is needed to understand pregnancy in AKU.
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Osteoporosis and fractures are common features of alkaptonuria. INTRODUCTION: A large cohort of alkaptonuria (AKU) patients was studied to better recognise and characterise osteoporosis and fractures in AKU. METHODS: Assessments including questionnaire analysis, DEXA and CT densitometry at the neck of femur (FN), total hip (TH) and lumbar spine (LS) were performed on patients at baseline when 2 mg nitisinone was commenced, and yearly thereafter. Blood and urine samples were collected for chemical measurement. CT BMD Z-scores were generated. RESULTS: Between June 2007 and March 2020, 87 AKU patients attended the NAC. At baseline, there were 48 fractures in 39 patients. Prevalence of osteoporosis was 3.1 at FN, 10.8 at TH and 24.7% at LS respectively. Prevalence of fragility fractures was greatly increased at 44.8%. The group with fractures showed increased ochronosis scores (p < 0.05). CT LS showed an inverse relationship with fractures (R = - 0.28; p < 0.05). CT LS was significantly lower in the fracture group (p < 0.002). Following nitisinone only, CT FN and CT TH decreased significantly (p < 0.05 and 0.01 respectively). Following nitisinone plus antiresorptive therapy, CT FN, CT TH and CT LS all increased significantly (p < 0.05, 0.05 and 0.001 respectively). However, patients on nitisinone plus antiresorptive had more fractures than nitisinone and no-treatment groups (p < 0.05). CONCLUSIONS: Osteopenia and fragility fractures are common in AKU.. Anti-resorptive therapy increased BMD in AKU without decreasing fragility fractures. Bone densitometry measurements by DXA are less reliable than quantitative CT at the LS in AKU.
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Alcaptonuria , Fracturas Óseas , Osteoporosis , Alcaptonuria/complicaciones , Alcaptonuria/diagnóstico , Alcaptonuria/tratamiento farmacológico , Densidad Ósea , Análisis de Datos , Humanos , Osteoporosis/diagnóstico , Osteoporosis/tratamiento farmacológico , Osteoporosis/epidemiología , Reino UnidoRESUMEN
Haemolysis and methaemoglobinaemia (MetHb) are rare metabolic complications that can occur in Alkaptonuria (AKU), for which there is no curative treatment. Presented is a case of a man who had AKU, and serves as a reminder of life-threatening complications that can occur with haemolysis and MetHb. This case presents an opportunity to revisit important considerations relating to the investigation and treatment of haemolysis and MetHb with a view to raising awareness, and in doing so hopefully reducing the uniformly fatal outcome. Additionally it is proposed that treatment of haemolysis and MetHb with nitisinone is considered as a potentially lifesaving treatment as it is believed that reducing the concentration of circulating homogentisic acid will reduce oxidative stress.
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Alcaptonuria , Ciclohexanonas/uso terapéutico , Inhibidores Enzimáticos/uso terapéutico , Nitrobenzoatos/uso terapéutico , Alcaptonuria/tratamiento farmacológico , Alcaptonuria/genética , Alcaptonuria/metabolismo , Animales , Modelos Animales de Enfermedad , Ácido Homogentísico/metabolismo , Humanos , Ratones , Tirosina/metabolismoRESUMEN
Nitisinone decreases homogentisic acid (HGA) in Alkaptonuria (AKU) by inhibiting the tyrosine metabolic pathway in humans. The effect of different daily doses of nitisinone on circulating and 24 h urinary excretion of phenylalanine (PA), tyrosine (TYR), hydroxyphenylpyruvate (HPPA), hydroxyphenyllactate (HPLA) and HGA in patients with AKU was studied over a four week period. Forty AKU patients, randomised into five groups of eight patients, received doses of 1, 2, 4 or 8 mg of nitisinone daily, or no drug (control). Metabolites were analysed by tandem mass spectrometry in 24 h urine and serum samples collected before and after nitisinone. Serum metabolites were corrected for total body water and the sum of 24 hr urine plus total body water metabolites of PA, TYR, HPPA, HPLA and HGA were determined. Body weight and urine urea were used to check on stability of diet and metabolism over the 4 weeks of study. The sum of quantities of urine metabolites (PA, TYR, HPPA, HPLA and HGA) were similar pre- and post-nitisinone. The sum of total body water metabolites were significantly higher post-nitisinone (p < 0.0001) at all doses. Similarly, combined 24 hr urine:total body water ratios for all analytes were significantly higher post-nitisinone, compared with pre-nitisinone baseline for all doses (p = 0.0002 - p < 0.0001). Significantly higher concentrations of metabolites from the tyrosine metabolic pathway were observed in a dose dependant manner following treatment with nitisinone and we speculate that, for the first time, experimental evidence of the metabolite pool that would otherwise be directed towards pigment formation, has been unmasked.
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Alcaptonuria/tratamiento farmacológico , Alcaptonuria/patología , Ciclohexanonas/uso terapéutico , Nitrobenzoatos/uso terapéutico , Tirosina/metabolismo , Adulto , Alcaptonuria/genética , Femenino , Ácido Homogentísico/sangre , Ácido Homogentísico/orina , Humanos , Masculino , Persona de Mediana Edad , Fenilalanina/sangre , Fenilalanina/orina , Pigmentos Biológicos/metabolismo , Espectrometría de Masas en Tándem , Tirosina/sangre , Tirosina/orinaRESUMEN
OBJECTIVES: We have assessed the effect of elevated concentrations of hydroxyphenylpyruvic acid (HPPA), hydroxyphenyllactic acid (HPLA) and tyrosine, on a range of chemistry tests in serum and urine to explore the potential for chemical interference on routine laboratory analyses in patients with alkaptonuria (AKU) treated with nitisinone and similarly implications for patients with hereditary tyrosinemia type 1 (HT-1). MATERIALS AND METHODS: HPPA, HPLA and tyrosine were added separately to pooled serum from subjects without AKU in a range of assays with Roche Modular chemistries. Effects on urine were assessed by changes in urine strip chemistries after mixing a positive control urine with various amounts of the test compounds and reading on a Siemens urine strip meter. RESULTS: No significant effect (pâ¯>â¯0.1) was observed up to 225⯵mol/L of HPPA and HPLA, and up to 5000⯵mol/L tyrosine, on any of the serum-based assays including those with peroxidase-coupled reaction systems of enzymatic creatinine, urate, total cholesterol, HDL cholesterol and triglyceride. Both the monohydroxy HPPA, and the dihydroxy homogentisic acid (HGA), at increased urine concentrations typical of nitisinone-treated AKU and non-treated AKU respectively, did however show marked negative interference in strip assays for glucose and leucocytes; i.e. those with peroxide-linked endpoints. The effect of increased HPLA was less marked. CONCLUSIONS: In patients with AKU or on nitisinone treatment and HT-1 patients on nitisinone, urine strip chemistry testing should be used sparingly, if at all, to avoid false negative reporting. It is recommended that urine assays should be organised with a suitable specialist laboratory.
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4-Hidroxifenilpiruvato Dioxigenasa/metabolismo , Alcaptonuria/tratamiento farmacológico , Alcaptonuria/metabolismo , Ciclohexanonas/uso terapéutico , Inhibidores Enzimáticos/uso terapéutico , Nitrobenzoatos/uso terapéutico , Fenilpropionatos/análisis , Ácidos Fenilpirúvicos/análisis , Tirosina/metabolismo , Alcaptonuria/sangre , Alcaptonuria/orina , Humanos , Fenilpropionatos/sangre , Fenilpropionatos/orina , Ácidos Fenilpirúvicos/sangre , Ácidos Fenilpirúvicos/orinaRESUMEN
OBJECTIVE: Nitisinone induced hypertyrosinaemia is a concern in patients with Alkaptonuria (AKU). It has been suggested that this may alter neurotransmitter metabolism, specifically dopamine and serotonin. Herein mass spectrometry imaging (MSI) is used for the direct measurement of 2,4-diphenyl-pyranylium tetrafluoroborate (DPP-TFB) derivatives of monoamine neurotransmitters in brain tissue from a murine model of AKU following treatment with nitisinone. METHODS: Metabolite changes were assessed using MSI on DPP-TFB derivatised fresh frozen tissue sections directing analysis towards primary amine neurotransmitters. Matched tail bleed plasma samples were analysed using LC-MS/MS. Eighteen BALB/c mice were included in this study: HGD-/- (n = 6, treated with nitisinone-4 mg/L, in drinking water); HGD-/- (n = 6, no treatment) and HGD+/- (n = 6, no treatment). RESULTS: Ion intensity and distribution of DPP-TFB derivatives in brain tissue for dopamine, 3-methoxytyramine, noradrenaline, tryptophan, serotonin, and glutamate were not significantly different following treatment with nitisinone in HGD -/- mice, and no significant differences were observed between HGD-/- and HGD+/- mice that received no treatment. Tyrosine (10-fold in both comparisons, p = 0.003; [BALB/c HGD-/- (n = 6) and BALB/c HGD+/- (n = 6) (no treatment) vs. BALB/c HGD-/- (n = 6, treated)] and tyramine (25-fold, p = 0.02; 32-fold, p = 0.02) increased significantly following treatment with nitisinone. Plasma tyrosine and homogentisic acid increased (ninefold, p = < 0.0001) and decreased (ninefold, p = 0.004), respectively in HGD-/- mice treated with nitisinone. CONCLUSIONS: Monoamine neurotransmitters in brain tissue from a murine model of AKU did not change following treatment with nitisinone. These findings have significant implications for patients with AKU as they suggest monoamine neurotransmitters are not altered following treatment with nitisinone.
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Encéfalo/metabolismo , Modelos Animales de Enfermedad , Metabolómica , Neurotransmisores/metabolismo , Tirosinemias/metabolismo , Administración Oral , Animales , Encéfalo/diagnóstico por imagen , Ciclohexanonas/administración & dosificación , Espectrometría de Masas , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Nitrobenzoatos/administración & dosificación , Imagen Óptica , Tirosinemias/sangre , Tirosinemias/inducido químicamenteRESUMEN
The original publication of this article contained an incorrect version that did not include some final reviewers' suggestions, was inadvertently received for production and published. The original article has been corrected.
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OBJECTIVE: Alkaptonuria (AKU) is a rare, inherited disorder of tyrosine metabolism, where patients are unable to breakdown homogentisic acid (HGA), which increases systemically over time. It presents with a clinical triad of features; HGA in urine, ochronosis of collagenous tissues, and the subsequent ochronotic arthritis of these tissues. In recent years the advance in the understanding of the disease and the potential treatment of the disorder looks promising with the data on the efficacy of nitisinone. However, there are limited methods for the detection and monitoring of ochronosis in vivo, or for treatment monitoring. The study aim was to test the hypothesis that Raman spectra would identify a distinct chemical fingerprint for the non-ochronotic, compared to ochronotic cartilage. DESIGN: Ochronotic and non-ochronotic cartilage from human hips and ears were analysed using Raman spectroscopy. RESULTS: Non-ochronotic cartilage spectra were similar and reproducible and typical of normal articular cartilage. Conversely, the ochronotic cartilage samples were highly fluorescent and displayed limited or no discernible Raman peaks in the spectra, in stark contrast to their non-ochronotic pairs. Interestingly, a novel peak was observed associated with the polymer of HGA in the ochronotic cartilage that was confirmed by analysis of pigment derived from synthetic HGA. CONCLUSION: This technique reveals novel data on the chemical differences in ochronotic compared with non-ochronotic cartilage, these differences are detectable by a technique that is already generating in vivo data and demonstrates the first possible procedure to monitor the progression of ochronosis in tissues of patients with AKU.
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Alcaptonuria/patología , Cartílago Articular/patología , Cartílago Auricular/patología , Articulación de la Cadera/patología , Ocronosis/patología , Espectrometría Raman , Adolescente , Adulto , Anciano , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
Alkaptonuria is a rare genetic disorder characterized by a high level of circulating (and urine) homogentisic acid (HGA), which contributes to ochronosis when it is deposited in connective tissue as a pigmented polymer. In an observational study carried out by National AKU Centre (NAC) in Liverpool, a total of thirty-nine AKU patients attended yearly visits in varying numbers. At each visit a mixture of clinical, joint and spinal assessments were carried out and the results calculated to yield an AKUSSI (Alkaptonuria Severity Score Index), see "Nitisinone arrests ochronosis and decreases rate of progression of Alkaptonuria: evaluation of the effect of nitisinone in the United Kingdom National Alkaptonuria Centre" (Ranganath at el., 2018). The aim of this data article is to produce visual representation of the change in the components of AKUSSI over 3 years, through radar charts. The metabolic effect of nitisinone is shown through box plots.