Novel gene associations in type 1 diabetes

Combined therapy of adenovirus vector mediated IGF-1 gene with anti-CD20 mAbs exerts potential beneficial role on type 1 diabetes in nonobese diabetic mice

AIMS

To assess the protective effects of combined treatment with anti-CD20 monoclonal antibody (mAb) and adenovirus mediated mouse insulin-like growth factor 1 (Adv-mIGF-1) gene on type 1 diabetes (T1D) in nonobese diabetic (NOD) mice at early stage.

METHODS

To simultaneously restore the proportion of Th cells and block the interaction of B cells, NOD model mice were assigned to four groups which received PBS, Adv-mIGF-1 gene and anti-CD20 mAbs alone or combination, respectively. After 16 weeks of therapeutic intervention, blood samples and pancreatic tissues of mice were measured via the methods of ELISA, RT-PCR, western blotting, H&E staining, TUNEL and immunohistochemistry assays.

KEY FINDINGS

Chronic combination intervention with Adv-mIGF-1 gene and anti-CD20 mAbs reduced the T1D-related morbidity, promoted the secretion of insulin, controlled the blood glucose levels (BGLs) and alleviated insulitis of experimental mice. In addition, current combination intervention also protected the pancreatic β cells via suppressing the expression of Fas and TNF-α, inhibiting Caspase-3/8 related apoptotic pathway, and activating the Bcl-2-related antiapoptotic pathway. Furthermore, current combination therapy also increased the expression levels of PDX-1 and CK-19 genes, and finally accelerated the proliferation and differentiation of pancreatic β-cells. In addition, combination therapy could also ameliorate the pathological characteristics of diabetic nephropathy in NOD mice.

CONCLUSION

Combination treatment with Adv-mIGF-1 gene and anti-CD20 mAbs may exert a potential beneficial role on T1D in NOD mice.

Risk genes and autoantibodies in Egyptian children with type 1 diabetes - low frequency of autoantibodies in carriers of the HLA-DRB1*04:05-DQA1*03-DQB1*02 risk haplotype

BACKGROUND

The study aimed to define the frequencies of type 1 diabetes-associated gene polymorphisms and their associations with various diabetes-associated autoantibodies in Egyptian children.

METHODS

One hundred and one children with type 1 diabetes and 160 healthy controls from the same region were studied for HLA-DQB1, HLA-DQA1, and HLA-DRB1 (DR4 subtypes) alleles; for INS and protein tyrosine phosphatase, non-receptor type 22 gene polymorphisms (rs689 and rs2476601); and for diabetes-associated autoantibodies.

RESULTS

Most children with diabetes (77.2%) were positive for the HLA-(DR3)-DQA1*05-DQB1*02 (DR3-DQ2) haplotype compared with 26.2% of the controls (OR = 9.5; p < 0.001). HLA-DRB1*04:02-DQA1*03-DQB1*03:02 (DR4-DQ8) (26.7%, OR = 3.3; p < 0.001), DRB1*04:05-DQA1*03-DQB1*02 (DR4-DQ2) (23.8%, OR 5.2; p < 0.001), and DRB1*04:05-DQA1*03-DQB1*03:02 (DR4-DQ8) (8.9%, OR = 7.7; p = 0.007) were also significantly increased. HLA-(DR15)-DQB1*06:01, (DR13)-DQB1*06:03, and DRB1*04:03-DQA1*03-DQB1*03:02 were the most protective haplotypes with OR values from 0.04 to 0.06. Patients positive for DR3-DQ2 but negative for DR4 haplotypes had a high frequency of glutamic acid decarboxylase antibodies (78%; p < 0.001 versus other genotypes), but only 26.6% of those with DR3-DQ2/DR4-DQ2 tested positive for glutamic acid decarboxylase antibodies (p = 0.006 versus other genotypes). Subjects with the DR4-DQ8 haplotype without DR3-DQ2 or DR4-DQ2 were more often positive for islet antigen-2 and zinc transporter 8 antibodies (55.5%, p = 0.007 and 55.5%, p = 0.01 respectively). The AA genotype of the INS gene was more common in patients than in controls (75.2 versus 59.5%, OR = 2.07; p = 0.018).

CONCLUSIONS

Besides a strong HLA-DR3-DQ2 association, a relatively high frequency of the DR4-DQ2 haplotype characterized the diabetic population. The low frequency of autoantibodies in children with HLA-DR4-DQ2 may indicate specific pathogenetic pathways associated with this haplotype.

Sociodemographic determinants of early weaning: a Finnish birth cohort study in infants with human leucocyte antigen-conferred susceptibility to type 1 diabetes

OBJECTIVE

To assess the most important sociodemographic determinants of age at introduction of complementary foods in infancy.

DESIGN

A prospective birth cohort with increased risk of type 1 diabetes, recruited between 1996 and 2004. The families completed at home a follow-up form on the age at introduction of new foods and, for each clinic visit, a structured dietary questionnaire with 3 d food records.

SETTING

Data from the Type 1 Diabetes Prediction and Prevention (DIPP) Project, Finland.

SUBJECTS

A cohort of 5991 infants (77 % of those invited) belonging to the DIPP Nutrition Study.

RESULTS

Sixty-three per cent of the infants were introduced to complementary foods, including infant formula, before the age of 4 months. The median age at introduction of infant formula was 1·5 months (range 0-18 months) and that of the first other complementary food 3·5 months (range 0·7-8 months). All sociodemographic and lifestyle factors studied were associated with the age at introduction of infant formula and/or first other complementary food. Female sex of the infant, being born in the southern region of Finland, living in a rural municipality, the presence of siblings, the mother or the father being a high-school graduate, high maternal professional education and maternal non-smoking during pregnancy predicted later introduction of complementary foods.

CONCLUSIONS

Compliance was relatively poor with the current recommendations for the age of introducing complementary foods. Small-sized young families with less well-educated parents were most prone to introduce complementary foods early.

Being born in Sweden increases the risk for type 1 diabetes - a study of migration of children to Sweden as a natural experiment

AIM

To investigate whether the age of first exposure to a high-incidence country like Sweden determines the risk of T1DM in children with an origin in a low incidence region of the world.

METHODS

Register study in a Swedish study population in the age 6-25 years in three categories of residents with an origin in low incidence regions of T1DM (Eastern Europe, East Asia, South Asia and Latin America); 24,252 international adoptees; 47,986 immigrants and 40,971 Swedish-born with two foreign-born parents and a comparison group of 1,770,092 children with Swedish-born parents. Retrieval of a prescription of insulin during 2006 was used as an indicator of T1DM and analysed with logistic regression.

RESULTS

The odds ratios (OR) for T1DM were lower than the Swedish majority population for residents with an origin in the four low incidence regions. Being Swedish-born implied a higher risk for T1DM in the four low incidence study groups compared with the internationally adopted with an OR of 1.68 (CI 1.03-2.73).

CONCLUSIONS

Being born in Sweden increases the risk for T1DM in children with an origin in low incidence countries. This may imply that exposures in utero or very early infancy are important risk factors for T1DM.

Expanded dog leukocyte antigen (DLA) single nucleotide polymorphism (SNP) genotyping reveals spurious class II associations

The dog leukocyte antigen (DLA) system contains many of the functional genes of the immune system, thereby making it a candidate region for involvement in immune-mediated disorders. A number of studies have identified associations between specific DLA class II haplotypes and canine immune hemolytic anemia, thyroiditis, immune polyarthritis, type I diabetes mellitus, hypoadrenocorticism, systemic lupus erythematosus-related disease complex, necrotizing meningoencephalitis (NME) and anal furunculosis. These studies have relied on sequencing approximately 300 bases of exon 2 of each of the DLA class II genes: DLA-DRB1, DLA-DQA1 and DLA-DQB1. In the present study, an association (odds ratio=4.29) was identified by this method between Weimaraner dogs with hypertrophic osteodystrophy (HOD) and DLA-DRB1∗01501. To fine map the association with HOD, a genotyping assay of 126 coding single nucleotide polymorphisms (SNPs) from across the entire DLA, spanning a region of 2.5 Mb (3,320,000-5,830,000) on CFA12, was developed and tested on Weimaraners with HOD, as well as two additional breeds with diseases associated with DLA class II: Nova Scotia duck tolling retrievers with hypoadrenocorticism and Pug dogs with NME. No significant associations were found between Weimaraners with HOD or Nova Scotia duck tolling retrievers with hypoadrenocorticism and SNPs spanning the DLA region. In contrast, significant associations were found with NME in Pug dogs, although the associated region extended beyond the class II genes. By including a larger number of genes from a larger genomic region, a SNP genotyping assay was generated that provides coverage of the extended DLA region and may be useful in identifying and fine mapping DLA associations in dogs.