Independence of carbohydrate-deficient isoforms of transferrin and cyclic citrullinated peptides in rheumatoid arthritis / Independência de isoformas de transferrina deficiente em carboidrato e peptídeos citrulinados cíclicos na artrite reumatoide

ABSTRACT Objective: The aim of this study was to assess the relationship between the two types of posttranslational modifications of proteins in RA: glycosylation on the example of carbohydrate-deficient transferrin and citrullination by means of autoantibodies to cyclic citrullinated peptides. Methods: The study was carried out in 50 RA patients. CDT was measured using N Latex CDT immunonephelometric test, the results were presented in absolute and relative units. Anti-CCP were measured using the chemiluminescent method and rheumatoid factor by immunoturbidimetric method. Results: 80% of RA patients were positive for anti-CCP, 70% for RF and 62% for both, anti-CCP and RF. The level of %CDT was significantly elevated, but absolute CDT level was not changed. The mean absolute CDT concentration was higher in anti-CCP positive patients than that in anti-CCP negative. CDT (absolute and relative concentration) did not correlate with anti-CCP and RF. However, serum RF significantly correlated with anti-CCP. %CDT did not correlate with anti-CCP, but absolute level correlated with anti-CCP only in anti-CCP negative and RF negative patients. CDT did not correlate with RF, but solely with anti-CCP in anti-CCP negative patients. Anti-CCP correlated with DAS 28 only in anti-CCP negative RA, but CDT (absolute and relative units) correlated with DAS 28 in all patients and in anti-CCP positive RA. Conclusions: These results suggest that the changes in CDT and anti-CCP concentrations are not associated with oneself and indicate on the independence of these posttranslational modifications in rheumatoid arthritis. Only the alterations in transferrin glycosylation reflected the activity of RA.

RESUMO Objetivo: Avaliar a relação entre os dois tipos de modificações pós-translacionais de proteínas na AR: glicosilação no caso da transferrina deficiente em carboidrato (TDC) e citrulinação por meio dos anticorpos no caso do antipeptídeo citrulinado cíclico (anti-CCP). Métodos: O estudo foi feito em 50 pacientes com AR. A TDC foi medida com o teste imunonefelométrico N Latex CDT e os resultados foram apresentados em unidades absolutas e relativas. O anti-CCP foi mensurado com o método quimioluminescente e o fator reumatoide (FR) pelo método imunoturbidimétrico. Resultados: Dos pacientes com AR, 80% foram positivos para anti-CCP, 70% para FR e 62% para ambos (anti-CCP e FR). A percentagem de transferrina total (%TDC) esteve significativamente elevada, mas o nível absoluto de TDC não esteve alterado. A concentração média de TDC absoluta foi maior nos pacientes anti-CCP positivos do que naqueles anti-CCP negativos. A TDC (concentração absoluta e relativa) não se correlacionou com o anti-CCP e o FR. No entanto, o FR sérico se correlacionou significativamente com o anti-CCP. O percentual de TDC não se correlacionou com o anti-CCP, mas seu nível absoluto se correlacionou com o anti-CCP apenas em pacientes FR negativos e anti-CCP negativos. A TDC não se correlacionou com o FR, somente com o anti-CCP em pacientes anti-CCP negativos. O anti-CCP se correlacionou com o DAS 28 apenas nos pacientes com AR anti-CCP negativos, mas a TDC (unidades absolutas e relativas) se correlacionou com o DAS 28 quando considerados todos os pacientes com AR e em pacientes com AR anti-CCP positivos. Conclusões: Esses resultados sugerem que as alterações na TDC e as concentrações de anti-CCP não estão associadas e indicam a independência dessas modificações pós-translacionais na artrite reumatoide. Apenas as alterações na glicosilação da transferrina refletem a atividade da AR.

Determination of Carbohydrate-deficient Transferrin Levels by Using Capillary Electrophoresis in a Korean Population / 대한진단검사의학회지

BACKGROUND: Carbohydrate-deficient transferrin (CDT) levels have rarely been determined in an Asian population. We evaluated the analytical performance of a test for measuring CDT levels by using capillary electrophoresis (EP). METHODS: We determined the precision of CDT measurement by using capillary EP and nephelometry and compared the CDT values obtained using both the methods. We included healthy control subjects, abstinent patients with liver disease, and individuals consuming varying amounts of alcohol. RESULTS: The CDT measurement by using capillary EP were correlated well with those CDT measurement by using nephelometry, N Latex CDT assay, Y=0.5706X+1.581, R=0.930. The results obtained from both methods showed good qualitative agreement with each other (kappa coefficient=0.61). Genetic variants of transferrin isoforms were detected in 4.1% of the tested population. Both the CDT and gamma-glutamyl transpeptidase (GGT) levels in the abstinent patients with liver disease were significantly higher than those in healthy abstinent individuals (0.9% vs. 0.5%, 109.5 mg/dL vs. 28.5 mg/dL, respectively), but the difference in CDT values in the 2 groups was less pronounced for the CDT values. Individuals who had a mean daily alcohol intake of more than 60 g/day showed significantly higher CDT levels than those who had a mean daily alcohol intake of less than 60 g/day (1.9% vs. 0.7%, P=0.03). CONCLUSIONS: The CDT test using capillary EP showed good performance, and this method has several advantages such as automation and detection of variant forms. Thus, CDT can be a more useful marker than GGT for monitoring alcohol abstinence, especially in patients with liver disease.

Carbohydrate-deficient Transferrin as a Marker of Heavy Drinking in Korean Males

This study was performed to evaluate the usefulness of carbohydrate-deficient transferrin (CDT) as a marker of heavy drinking in Korean males. The subjects (143 Korean males) were classified into 2 groups according to the amount of drinking, moderate drinkers (72 individuals) who drank 14 drinks or less per week and heavy drinkers (71 individuals) who drank more than 14 drinks per week. Using %CDT, gamma glutamyl transferase (GGT), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) as clinical markers for heavy drinking, sensitivity, specificity, positive and negative predictive values were investigated. Sensitivities of %CDT, GGT, AST, and ALT were 83.1%, 67.6%, 52.1% and 46.5%, respectively. Specificities were 63.9%, 45.8%, 72.2%, and 54.2%, respectively. Positive predictive values were 69.4%, 55.2%, 64.9%, and 50.0% respectively. Negative predictive values were 79.3%, 58.9%, 60.5%, and 50.6% respectively. The areas under the receiver operating characteristic curve (95% confidence interval) for %CDT, GGT, AST, and ALT were 0.823 (0.755-0.891), 0.578 (0.484-0.673), 0.622 (0.528-0.717), and 0.516 (0.420-0.613), respectively. CDT is considered as the most reliable marker for detecting heavy drinking in Korean males.

Prevalence of the hemochromatosis gene mutation in patients with nonalcoholic steatohepatitis and correlation with degree of liver fibrosis / Prevalência de mutação para o gene da hemocromatose em pacientes com esteatohepatite não-alcoólica e correlação com o grau de fibrose hepática

BACKGROUND: Nonalcoholic steatohepatitis is a chronic liver disease with a high prevalence in the general population and a potential to evolve into cirrhosis. It is speculated that iron overload could be associated with liver injury and unfavorable progress in affected patients. AIMS: To evaluate the prevalence of mutation of the hemochromatosis gene (HFE) in patients with nonalcoholic steatohepatitis and to correlate it with histological findings in liver specimens. PATIENTS AND METHODS: Twenty-nine patients with nonalcoholic steatohepatitis were evaluated. The presence of mutation in the hemochromatosis gene (C282Y and H63D) was tested in all patients and its result was evaluated in relation to hepatic inflammatory activity, presence of fibrosis, and iron overload in the liver. The control group was composed of 20 patients with normal liver function tests and 20 patients infected with the hepatitis C virus, with elevated serum levels of aminotransferases and with chronic hepatitis as shown by biopsy. RESULTS: Mutation of the hemochromatosis gene (C282Y and/or H63D) was diagnosed in 16 (55.2 percent) patients with nonalcoholic steatohepatitis, in 12 (60 percent) patients with hepatitis C and in 8 (40 percent) patients with no liver disease. No association was found between the presence of mutation and inflammatory activity, nor with the presence of fibrosis in patients with nonalcoholic steatohepatitis. An association was found between the presence of mutation and the occurrence of iron overload in liver, but there was no association between liver iron and the occurrence of fibrosis. CONCLUSIONS: The findings suggest that iron does not play a major role in the pathogenesis and progression of nonalcoholic steatohepatitis, and routine tests of the hemochromatosis gene mutation in these patients should not be recommended.

RACIONAL: A esteatohepatite não-alcoólica é uma doença crônica, com elevada prevalência na população e com potencial evolutivo. Especula-se que a sobrecarga de ferro possa estar associada com a injúria hepática e com uma evolução desfavorável destes pacientes. OBJETIVOS: Avaliar a prevalência da mutação do gene da hemocromatose (HFE) em pacientes com esteatohepatite não-alcoólica e correlacioná-la com os achados histológicos hepáticos. PACIENTES E MÉTODOS: Foram avaliados 29 pacientes com esteatohepatite não-alcoólica. A presença da mutação do HFE (C282Y e H63D) foi testada em todos os pacientes e seu resultado foi avaliado em relação a atividade inflamatória hepática, presença de fibrose e depósitos hepático de ferro. Como grupo controle estudou-se 20 pacientes com provas de função hepática normal e 20 pacientes portadores do vírus da hepatite C, com elevação dos níveis de aminotransferases e biópsia revelando hepatite crônica. RESULTADOS: A mutação do HFE (C282Y e/ou H63D) foi diagnosticada em 16 (55,2 por cento) pacientes com esteatohepatite não-alcoólica, em 12 (60 por cento) pacientes com hepatite C e em 8 (40 por cento) pacientes sem doença hepática. Não se observou associação entre a presença da mutação e a atividade inflamatória e a presença de fibrose nos pacientes com esteatohepatite não-alcoólica. Foi observada associação entre a presença de mutação e a ocorrência de depósitos de ferro hepático, porém, não ocorreu associação entre o ferro hepático e a ocorrência de fibrose. CONCLUSÕES: Os achados sugerem que o ferro não exerce papel importante na patogenia e na evolução da esteatohepatite não-alcoólica e a pesquisa rotineira da mutação do HFE nestes pacientes não deve ser recomendada.