RESUMO
The involvement of the immune system has been hypothesized in the pathogenesis of amyotrophic lateral sclerosis (ALS). In this study a significantly higher level of TNF-alpha and its soluble receptors, TNF-R1 and TNF-R2, has been found in plasma of patients affected by the sporadic form of ALS compared to normal subjects. The genetic analysis of the polymorphisms of TNF-alpha, TNF-R1 and TNF-R2 showed no statistically significant differences in alleles and genotype frequencies between patients and controls. These data suggest a participation of the immune system in response to as far unknown intracellular signals.
Assuntos
Esclerose Lateral Amiotrófica/sangue , Receptores Tipo II do Fator de Necrose Tumoral/sangue , Receptores Tipo I de Fatores de Necrose Tumoral/sangue , Fator de Necrose Tumoral alfa/sangue , Idoso , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/imunologia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estresse Oxidativo , Polimorfismo de Fragmento de Restrição , Receptores Tipo I de Fatores de Necrose Tumoral/genética , Receptores Tipo I de Fatores de Necrose Tumoral/fisiologia , Receptores Tipo II do Fator de Necrose Tumoral/genética , Receptores Tipo II do Fator de Necrose Tumoral/fisiologia , Solubilidade , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/fisiologiaRESUMO
Subjects with certain HLA alleles have a higher risk of specific autoimmune diseases than those without these alleles. The 8.1 ancestral haplotype (AH) is a common Caucasoid haplotype carried by most people who type for HLA-B8,DR3. It is unique in its association with a wide range of immunopathological diseases. To gain insight into the identification of the mechanism(s) of disease susceptibility of 8.1 AH carriers, we have investigated the prevalence of circulating immune complexes and non-organ-specific autoantibodies in healthy carriers of the haplotype. The results show that carriers of 8.1 AH display both a significant increased prevalence of immune complexes and higher titers of anti-nuclear autoantibodies. This AH carries a single segment characterized by no C4A gene. This null allele does not code for a functional C4A protein that likely plays an anti-inflammatory role being specialized in the opsonization and immunoclearance processes. So, this genetic defect has been claimed to allow that an increased production of autoantibodies directed vs. cells that have undergone apoptosis and are not efficiently disposed because a reduced antigenic clearance. The results obtained in the present study fit very well with this hypothesis. In the AH carriers the simultaneous high setting of tumor necrosis factor (TNF)-alpha may supply the autoantigens (providing an excess of apoptotic cells) that drive the autoimmune response. In conclusion, the C4 defect associated to the increased spontaneous release of TNF-alpha, modifying a certain number of immunological parameter may be the most characterizing feature of the 8.1 AH. In the majority of individuals, an autoimmune response clinically relevant will develop only in the presence of other immunological abnormalities.
Assuntos
Doenças Autoimunes/etiologia , Complemento C4/genética , Antígenos HLA/genética , Haplótipos/genética , Adulto , Alelos , Doenças Autoimunes/genética , Doenças Autoimunes/imunologia , Ensaio de Imunoadsorção Enzimática , Feminino , Frequência do Gene/genética , Antígeno HLA-B8/genética , Antígeno HLA-DR3/genética , Haplótipos/imunologia , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Sarcoidosis is likely to result from exposure of genetically susceptible hosts to environmental agents. Erythrocyte (E) complement receptor 1 (CR1) is a membrane protein mediating the transport of immune complexes (ICs) to phagocytes, and at least three polymorphisms on the CR1 gene are related to erythrocyte surface density of CR1 molecules, in turn related to the rate of IC clearance from circulation. We hypothesized that sarcoidosis could be associated with increased frequency of the CR1 gene alleles coding for reduced CR1/E ratio. We studied 91 sarcoid patients and two control groups: 94 healthy volunteers and 71 patients with chronic obstructive pulmonary disease (COPD). Three polymorphic sites of CR1 gene, His1208Arg, intron 27 HindIII/RFLP, and Pro1827Arg, were analyzed. The three polymorphisms were in linkage disequilibrium. The GG genotype for the Pro1827Arg (C(5507)G) polymorphism was significantly associated with sarcoidosis in comparison to both control groups (odds ratio [OR] = 3.13; 95% confidence interval [CI] 1.49-6.69 versus healthy control subjects, and OR= 2.82, 95% CI 1.27-6.39 versus COPD control subjects). The same genotype was particularly associated to disease in females (OR = 7.05; 95% CI 3.10-16.61 versus healthy control subjects). These findings agree with speculations on the role of CR1 gene as a possible susceptibility factor.