RESUMO
Type 1 diabetes (T1D) has a strong genetic component and the major locus lies in the HLA DQB1 region. We found earlier an increased apoptosis with decreased viability and function of the CD4+CD25+(high) T-cell subset (Treg) in human subjects with recent-onset T1D and in multiple autoantibody-positive, high at-risk individuals. Tregs normally inhibit or delay onset of T1D in animal models and increased Treg apoptosis could bring on or accelerate disease from effector T-cell-mediated destruction of insulin-producing beta cells. In this study, we test the hypothesis that HLA DQB1 genotypes are associated with increased CD4+CD25+(high) T-cell apoptosis. HLA DQ-based genetic risk status was significantly associated with CD4+CD25+(high) T-cell apoptosis, after adjustment for age, gender and phenotypic status (n=83, F=4.04 (d.f.=3), P=0.01). Unaffected, autoantibody-negative high risk HLA DQB1 control subjects showed increased CD4+CD25+(high) apoptosis levels compared with low risk HLA DQB1 control subjects (n=26, P=0.002), confirming that the association precedes disease. The association of specific HLA DQB1 genotypes with Treg apoptosis was also tested, showing significance for HLA DQB1*0302, DQB1*0201 and HLA DQB1*0602 alleles. Our study shows an association of HLA DQB1 genotypes with CD4+CD25+(high) T-cell apoptosis, which implicates CD4+CD25+(high) T-cell apoptosis as a new intermediate trait for T1D.
Assuntos
Apoptose/genética , Diabetes Mellitus Tipo 1/genética , Antígenos HLA-DQ/genética , Glicoproteínas de Membrana/genética , Adolescente , Adulto , Alelos , Apoptose/imunologia , Antígenos CD4/imunologia , Criança , Diabetes Mellitus Tipo 1/imunologia , Feminino , Predisposição Genética para Doença , Genótipo , Antígenos HLA-DQ/imunologia , Cadeias beta de HLA-DQ , Humanos , Subunidade alfa de Receptor de Interleucina-2/genética , Masculino , Glicoproteínas de Membrana/imunologia , Subpopulações de Linfócitos T/imunologia , Linfócitos T Reguladores/imunologia , Adulto JovemRESUMO
BACKGROUND: : Inherited mutations in the CDKN2A tumor suppressor gene, which encodes the p16(INK4a) protein, and in the cyclin-dependent kinase 4 (CDK4) gene confer susceptibility to cutaneous malignant melanoma. We analyzed families with two or more cases of melanoma for germline mutations in CDKN2A and CDK4 to elucidate the contribution of these gene defects to familial malignant melanoma and to the occurrence of other cancer types. METHODS: : The entire CDKN2A coding region and exon 2 of the CDK4 gene of an affected member of each of 52 families from southern Sweden with at least two cases of melanoma in first- or second-degree relatives were screened for mutations by use of polymerase chain reaction-single-strand conformation polymorphism analysis. Statistical tests were two-sided. RESULTS: : CDKN2A mutations were found in 10 (19%) of the 52 families. Nine families carried an identical alteration consisting of the insertion of arginine at position 113 of p16(INK4a), and one carried a missense mutation, in which the valine at position 115 was replaced with a glycine. The 113insArg mutant p16(INK4a) was unable to bind cdk4 and cdk6 in an in vitro binding assay. Six of the 113insArg families had at least one member with multiple primary melanomas; the 113insArg families also had a high frequency of other malignancies-in particular, breast cancer (a total of eight cases compared with the expected 2.1; P =.0014) and pancreatic cancer (a total of six cases compared with the expected 0.16; P<.0001). Families with breast cancer also had a propensity for multiple melanomas in females, suggesting that a sex-dependent factor may modify the phenotypic expression of CDKN2A alterations. CONCLUSIONS: : Our findings confirm that the majority of CDKN2A-associated melanoma families in Sweden are due to a single founder mutation. They also show that families with the CDKN2A 113insArg mutation have an increased risk not only of multiple melanomas and pancreatic carcinoma but also of breast cancer.
Assuntos
Neoplasias da Mama/genética , Melanoma/genética , Mutação , Neoplasias Primárias Múltiplas/genética , Neoplasias Pancreáticas/genética , Neoplasias Cutâneas/genética , Sequência de Aminoácidos , Feminino , Genes p16 , Humanos , Masculino , Dados de Sequência Molecular , Linhagem , Reação em Cadeia da Polimerase/métodos , Polimorfismo Conformacional de Fita Simples , Regiões Promotoras Genéticas/genética , Risco , Fatores Sexuais , SuéciaRESUMO
Unpurified stroma-free hemoglobin (SFH) from water-lysed human red blood cells, hemoglobin Ao (HbAo), and hemoglobin cross-linked between alpha chains with 3,5-bis-dibromosalicyl-fumarate (HbXLDBBF) were infused into isolated perfused rabbit hearts. Vasoactivity and myocardial performance were determined using an isovolumic Langendorff preparation. With constant coronary flow, infusion of SFH (55 mg/dl) resulted in a 56% increase in aortic pressure as opposed to 29% and 11% increases with HbAo and HbXLDBBF, respectively. Rates of aortic pressure increase were over 6 times greater with SFH than with either HbAo or HbXLDBBF and exhibited concentration dependence only with SFH. Myocardial function remained normal. With constant coronary pressure, coronary flow decreased by 36% with SFH accompanied by a 23% decline in left ventricular developed pressure indicative of ischemia. With HbAo or HbXLDBBF, coronary flow decreased by only 1/3 that with SFH, while developed pressure declined by 4% and 2% with HbAo and HbXLDBBF, respectively. These data suggest that purification of HbAo to a single component can eliminate the dominant of at least two distinct vasoactive factors normally found in SFH. Furthermore, the physiological significance of the vascular response to HbAo is minimal. Preparations of HbXLDBBF accomplish this same result.