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Doctoral Thesis
DOI
10.11606/T.5.2010.tde-04112010-124658
Document
Author
Full name
Debora Lucia Seguro Danilovic
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2010
Supervisor
Committee
Marui, Suemi (President)
Corrêa, Maria Cassia Jacintho Mendes
Pessôa, Mário Guimarães
Silva, Magnus Régios Dias da
Silva, Maria Elizabeth Rossi da
Title in Portuguese
Avaliação tireoidiana de pacientes infectados pelo vírus da hepatite C: correlação com polimorfismos do gene CTLA4
Keywords in Portuguese
CTLA4
Doenças auto-imunes
Globulina ligante de tiroxina
Hepatite C
Interferon alfa
Tireóide
Abstract in Portuguese
INTRODUÇÃO: Manifestações auto-imunes são frequentes na infecção pelo vírus da hepatite C (VHC). Apesar da associação com doenças auto-imunes de tireóide (DAIT) ser controversa, sabe-se que distúrbios tireoidianos podem surgir ou piorar com tratamento com IFN e ribavirina. Os objetivos deste estudo foram avaliar a função tireoidiana em pacientes infectados pelo VHC, caracterizar distúrbios tireoidianos antes, durante e após tratamento com IFN e estudar as frequências dos genótipos dos polimorfismos do gene CTLA4, correlacionando-os com características clínicas e laboratoriais, presença de disfunção tireoidiana e evolução durante tratamento com IFN. MÉTODOS: Avaliação prospectiva de 112 indivíduos com infecção crônica pelo VHC, 30 tratados com IFN, e 183 controles. Realizaram-se avaliações clínica, hormonal e de auto-imunidade tireoidiana e ultra-sonografia de tireóide no início e durante tratamento. Avaliações de globulina transportadora de hormônios tireoidianos (TBG), de CXCL10 e de biópsia hepática foram feitas pré-tratamento. Análises dos polimorfismos do gene CTLA4 -318C>T, A49G e CT60 foram realizadas por PCR-RFLP e de AT(n) por análise de fragmento através de eletroforese capilar. RESULTADOS: A frequência de DAIT entre infectados por VHC não diferiu dos controles (10,7 vs 13,5%, p=0,585). Os limites de distribuição dos níveis de T3 (T3T) e T4 (T4T) totais foram superiores aos de referência (T3T 112-246 ng/dL; T4T 7,8-15,2 g/dL), assim como de TBG (17-47 mg/L). TBG correlacionou-se com T3T (r=0,654, p<0,001) e T4T (r=0,741, p<0,001). Heterogeneidade (p=0,027) e hipoecogenicidade de parênquima (p=0,002) foram mais frequentes nos pacientes com DAIT. Aumento de vascularização esteve presente em 49,2% dos infectados sem distúrbio tireoidiano. CXCL10 esteve aumentada nos infectados (p=0,006), mas não se relacionou com disfunção tireoidiana. Sua elevação correspondeu ao grau de atividade necro-inflamatória na biópsia hepática (p=0,006) e correlacionou-se com T3T (r=0,388, p=0,003), T4T (r=0,444, p=0,001) e TBG (r=0,551, p<0,001). Dezenove por cento dos pacientes desenvolveram tireoidites auto-imunes por IFN e 16% não auto-imunes. Em 14 pacientes sem alteração tireoidiana durante o uso de IFN, T3T diminuiu ao longo de 12 meses (p=0,038) concomitante à queda de ALT (p=0,055). T4T diminuiu com 3 (p=0,039) e 12 meses (p=0,008), T4 livre e TSH permaneceram estáveis. Encontrou-se maior frequência de oito repetições AT na região 3UTR do gene CTLA4 nos infectados por VHC (p=0,019). O alelo C do polimorfismo -318C>T esteve relacionado com infecção pelos genótipos 1 (p=0,020, OR 0,19) e 3 (p=0,008, OR 9,13), assim como o alelo G do polimorfismo A49G (p=0,002, OR 0,38 e p=0,004, OR 2,49, respectivamente). Não se identificou relação dos polimorfismos do gene CTLA4 com distúrbios tireoidianos, antes ou após tratamento com IFN. CONCLUSÕES: Não foi encontrada associação entre infecção por VHC e doenças tireoidianas. Indivíduos infectados por VHC têm maiores níveis de T3T e T4T, correlacionados com TBG. Aumento de CXCL10 não se associou com disfunção tireoidiana, mas se correlacionou com TBG, T3T e T4T. IFN provocou tireoidites auto-imunes e não auto-imunes, além de reduzir T3T e T4T coincidente com melhora de lesão hepática. Não se encontrou relação dos polimorfismos do gene CTLA4 com características clínicas e laboratoriais ou presença de disfunção tireoidiana prévia ou induzida por IFN
Title in English
Thyroid evaluation of patients infected by hepatitis C virus: correlation with polymorphisms of CTLA4 gene
Keywords in English
Alpha-interferon
Autoimmune diseases
CTLA4
Hepatitis C
Thyroid
Thyroxine-binding globulin
Abstract in English
INTRODUCTION: Autoimmune disorders are frequent in patients infected by the hepatitis C virus (HCV). Although the association with autoimmune thyroid diseases (AITD) is controversial, thyroid disturbance could occur or worsen with IFN and ribavirin treatment. The aims of the study were evaluate thyroid function in HCV-infected patients, characterize thyroid disturbance prior and after IFN treatment and analyze the frequency of the genotypes of the polymorphisms of CTLA4 gene, and their relation to clinical and laboratorial features, presence of thyroid dysfunction and disturbance along IFN treatment. METHODS: Prospective evaluation of 112 chronically HCV-infected subjects, 30 treated with IFN, and 183 controls. Clinical, hormonal, thyroid autoimmunity and ultrasound exams were performed before and during treatment. Thyroxine-binding globulin (TBG), CXCL10 and hepatic biopsies were also evaluated before treatment. Analysis of polymorphisms of CTLA4 gene -318C>T, A49G and CT60 were made by PCR-RFLP and AT(n) polymorphism analysis by capillary electrophoresis in automatic sequencer. RESULTS: The frequency of AITD among HCV-infected subjects was similar to the rate among controls (10.7 vs 13.5%, p=0.585). Total T3 (T3T) and T4 (T4T) distributions were right shifted (T3T 112-246 ng/dL; T4T 7.8-15.2 g/dL), as was TBG (17-47 mg/L). TBG correlated to both T3T (r=0.654, p<0.001) and T4T (r=0.741, p<0.001). Thyroid heterogeneity (p=0.027) and hipoechogenicity (p=0.002) were associated with AITD and, most notably, increased vascularization was present in 49.2% of HCV-infected patients without thyroid disturbance. CXCL10 was higher in HCV-infected group (p=0.006) but was not related to thyroid dysfunction. Increase in CXCL10 levels were consistent with hepatic necroinflammatory activity (p=0.006) and correlated to T3T (r=0.388, p=0.003), T4T (r=0.444, p=0.001) and TBG (r=0.551, p<0.001). Nineteen percent of subjects treated with IFN presented autoimmune thyroiditis and 16% had non-autoimmune thyroiditis. In 14 subjects without IFN-induced thyroid dysfunction, T3T decreased along 12 months of follow-up (p=0.038) concomitant to ALT decrease (p=0.055). T4T decreased within 3 (p=0.039) and 12 months (p=0.008), while both free T4 and TSH remained stable. Eight AT repetitions in 3UTR site of the CTLA4 gene were more frequent among HCV-infected subjects. The C allele of -318C>T polymorphism was associated with genotype 1 (p=0.020, OR 0.19) and 3 infections (p=0.008, OR 9.13), similar to allele G of A49G polymorphism (p=0.002, OR 0.38 and p=0.004, OR 2.49, respectively). No association of the polymorphisms of CTLA4 gene and thyroid disorders, prior or induced by IFN treatment, was found. CONCLUSIONS: No association between HCV-infection and thyroid diseases was found. HCV-infected subjects had higher T3T and T4T which were correlated to TBG. Increased CXCL10 was not associated to thyroid dysfunction, but correlated to TBG, T3T and T4T. IFN induced autoimmune and non-autoimmune thyroiditis. IFN also reduced T3T and T4T levels commensurately with liver improvement. The polymorphisms of CTLA4 gene were not associated with clinical and laboratorial features or presence of thyroid dysfunction, prior or induced by IFN
 
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Publishing Date
2010-11-09
 
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