Toll-like receptor 3 (TLR3) and the development of type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is a chronic, progressive autoimmune disease characterized by metabolic decompensation often leading to dehydration and ketoacidosis. Viral agents seem to play an important role in triggering the autoimmune destruction that leads to the development of T1DM. Among several viral strains investigated so far, the enterovirus family has been consistently associated with the onset of T1DM in humans. One of the mediators of viral damage is the double-stranded RNA (dsRNA) generated during replication and transcription of viral RNA and DNA. The Toll-like receptor 3 (TLR3) gene codes for an endoplasmic receptor of the pattern-recognition receptors (PRRs) family that recognizes dsRNA, plays an important role in the innate immune response triggered by viral infection. Binding of dsRNA to the TLR3 triggers the release of proinflammatory cytokines, such as interferons, which exhibit potent antiviral action; thus, protecting uninfected cells and inducing apoptosis of infected ones. Therefore, the TLR3 gene is a good candidate for the development of T1DM. Within this context, the objective of the present review was to address the role of the TLR3 gene in the development of T1DM. Arch Endocrinol Metab. 2015;59(1):4-12.

The role of interferon induced with helicase C domain 1 (IFIH1) in the development of type 1 diabetes mellitus / O papel do interferon induzido com o domínio C da helicase 1 (IFIH1) no desenvolvimento do diabetes melito tipo 1

Type 1 diabetes mellitus (T1DM) is a chronic, progressive, autoimmune disease characterized by metabolic decompensation frequently leading to dehydration and ketoacidosis. Viral pathogens seem to play a major role in triggering the autoimmune destruction that leads to the development of T1DM. Among several viral strains investigated so far, enteroviruses have been consistently associated with T1DM in humans. One of the mediators of viral damage is the double-stranded RNA (dsRNA) generated during replication and transcription of viral RNA and DNA. The IFIH1 gene encodes a cytoplasmic receptor of the pattern-recognition receptors (PRRs) family that recognizes dsRNA, playing a role in the innate immune response triggered by viral infection. Binding of dsRNA to this PRR triggers the release of proinflammatory cytokines, such as interferons (IFNs), which exhibit potent antiviral activity, protecting uninfected cells and inducing apoptosis of infected cells. The IFIH1 gene appears to play a major role in the development of some autoimmune diseases, and it is, therefore, a candidate gene for T1DM. Within this context, the objective of the present review was to address the role of IFIH1 in the development of T1DM.

O diabetes melito tipo 1 (T1DM) é uma doença autoimune crônica e progressiva caracterizada por descompensações metabólicas frequentemente acompanhadas por desidratação e cetoacidose. Os agentes virais parecem ter um papel importante no desencadeamento da destruição autoimune que leva ao desenvolvimento do T1DM. Entre as cepas virais estudadas até agora, a família dos enterovírus foi consistentemente associada ao surgimento da doença em humanos. Um dos mediadores do dano viral é o RNA fita dupla (RNAfd) gerado durante a replicação e transcrição de RNA e DNA viral. O gene IFIH1 codifica um receptor citoplasmático pertencente à família dos pattern-recognition receptors (PRRs) que reconhece o RNAfd, tendo um papel importante na resposta imune inata desencadeada por infecção viral. A ligação do RNAfd a essa PRR desencadeia a liberação de citocinas pró-inflamatórias como interferons (IFNs), os quais exibem uma potente ação antiviral e têm como objetivo proteger as células não infectadas e induzir apoptose naquelas já contaminadas. O gene IFIH1 parece ter uma participação importante no desenvolvimento de algumas doenças autoimunes. Por isso, esse gene é um candidato ao desenvolvimento do T1DM. Dentro desse contexto, o objetivo da presente revisão foi abordar o papel do IFIH1 no desenvolvimento do T1DM.

Diabetes melito do tipo 1A na primeira infância de gêmeos dizigóticos: associação entre fatores genéticos e ambientais / Early infancy onset of type 1A diabetes mellitus in dizygotic twins: association with genetic and environmental factors

O Diabetes Mellitus tipo 1A diagnosticado antes do 1° ano de vida é uma condição rara, podendo haver uma associação entre fatores genéticos e ambientais (infecção) que explique tal precocidade. Foi descrita a presença do genoma do Citomegalovírus (CMV) nos linfócitos, em cerca de 15 por cento de novos casos de DM1. Relatamos os casos de desenvolvimento do diabetes em gêmeos dizigóticos do sexo masculino, nos primeiros 9 meses de idade com identidade nos alelos HLA (DR3/DR4) e história de infecção pelo CMV em ambos, comprovada por IgG+ e PCR urinária. Apenas o 2° gemelar apresentava o anticorpo anti-GAD positivo (9,6 UI/mL). Apesar de tratar-se de gêmeos dizigóticos, cuja taxa de concordância para diabetes, na literatura, é de 3,8 por cento, assumem risco equivalente a monozigóticos (de 40 por cento) por apresentarem HLA de alto risco para o diabetes. Acreditamos que tanto a concordância temporal como o início precoce do diabetes são decorrentes da associação entre infecção por CMV e forte suscetibilidade genética.

The onset of type 1A diabetes before the first year of age is a rare condition and is probably due to an interaction between genetic and environmental factors (infection), which, together, may explain such an early event. Studies say that about 15 percent of newly diagnosed type 1 diabetic patients had human Cytomegalovirus (CMV) specific viral genome in their lymphocytes. We report two cases of dizygotic twins with type 1 diabetes onset in their first 9 months of age, with genetic homogeneity (for HLA DR3/DR4 alleles), a history of CMV infection (positive IgG and urinary PCR) and positive antibody anti-GAD (9.6 UI/ml), present only in the second twin. Although they were dizygotic twins, which concordance rate is 3.8 percent, they assume the equivalent risk as monozygotic (40 percent) as they have similar high risk genotype (HLA) for type 1 diabetes. We believe that both time concordance and also the early onset of diabetes are due to an association between infection and the high genetic liability.

Possible relationship betwssn diabetes and hepatitis virus C infection

The prevalence of hepatitis [C] virus antibodies [HCV antibodies] was determined on sera obtained from seventy five diabetic patients attending the out patient Diabetic Clinic at the Main Alexandria University Hospital [25 with insulin dependent diabetes mellitus-IDDM-and 50 with non insulin dependent diabetes mellitus- NIDDM-] Along with 18 age and sex matched healthy control subjects. Second generation enzyme immunoassay [ELISA-2] screening test and recombinant immunoblot assay [RIBA-2] as confirmatory test were utilized [Orthodiagnostics]. The 25 IDDM patients [12 females and 13 males] were on insulin therapy. Their age was 18-28 years, and the main duration of diabetes was 40 months. Nine age and sex matched healthy volunteers were studied as controls. The HCV prevalence was found to be non significantly different between both groups [8% VS 11.1% NS]. The included 50 NIDDM patients [28 females, 22 males] were on diet or oral hypoglycaemics, none had received insulin therapy. Their age range between 32-35 years and the mean duration of diabetes was 18 months. Nine age and sex matched controls were also studied. HCV antibodies were found to be equally frequent in both groups [11.1%]. The possible risk factors for acquisition of HCV viz age, sex, duration of disease, history of schistosomiasis, jaundice, blood transfusion, dental or surgical manipulations were studied using a multivariate analysis. Only schistosomiasis was found to be significantly associated with HCV infection among the NIDDM patients [O.R. = 6.8]. We can conclude that there is no significant association between IDDM or NIDDM and increased risk of seropositivity for HCV antibodies