[Association of the incidence of type 1 diabetes mellitus with environmental factors in Chile during the period 2000-2007]. / Estudio temporal de diabetes mellitus tipo 1 en Chile: asociación con factores ambientales durante el período 2000-2007.

BACKGROUND: Pollution and viral infections could be associated with the incidence of type 1 diabetes mellitus. AIM: To look for associations between the temporal patterns of Type 1 Diabetes Mellitus (T1D) in infants younger than the age of 15 years, and environmental factors, such as air pollution and viruses. MATERIAL AND METHODS: Data registries from hospitals, emergency services, and the Infantile Diabetes Foundation were reviewed, corresponding to children aged less than 15 years, who received their first insulin injection between 2000 and 2007. The incidence of type 1 diabetes was computed for each epidemiological week. Environmental ozone and particulate matter rates for each week were obtained from Environmental services. Rates of influenza and respiratory syncytial virus infections were obtained from the epidemiological department of the Ministry of Health. An ecological Bayesian Poisson regression model was fitted, introducing the covariates, lagged covariates and errors, to estimate the incidence by epidemiological week. RESULTS: Three factors were significant by the proposed model: particulate matter PPM 2.5 (relative risk (RR): 1.003) lagged by two weeks, influenza (RR: 0.1808) and RSV (RR: 1.021). Trends and seasonality were clearly controlled by these covariates, considering the epidemiological week as a counting period. CONCLUSIONS: These results show that environmental factors could be related to peaks of type 1 diabetes incidence.

Estudio temporal de diabetes mellitus tipo 1 en Chile: asociación con factores ambientales durante el período 2000-2007 / Association of the incidence of type 1 diabetes mellitus with environmental factors in Chile during the period 2000-2007

Background: Pollution and viral infections could be associated with the incidence of type 1 diabetes mellitus. Aim: To look for associations between the temporal patterns of Type 1 Diabetes Mellitus (T1D) in infants younger than the age of 15years, and environmental factors, such as air pollution and viruses. Material and Methods: Data registries from hospitals, emergency services, and the Infantile Diabetes Foundation were reviewed, corresponding to children aged less than 15years, who received their first insulin injection between 2000 and 2007. The incidence of type 1 diabetes was computed for each epidemiological week. Environmental ozone and particulate matter rates for each week were obtained from Environmental services. Rates of influenza and respiratory syncytial virus infections were obtained from the epidemiological department of the Ministry of Health. An ecological Bayesian Poisson regression model was fitted, introducing the covariates, lagged covariates and errors, to estimate the incidence by epidemiological week. Results: Three factors were significant by the proposed model: particulate matter PPM 2.5 (relative risk (RR): 1.003) lagged by two weeks, influenza (RR: 0.1808) and RSV (RR: 1.021). Trends and seasonality were clearly controlled by these covariates, considering the epidemiological week as a counting period. Conclusions: These results show that environmental factors could be related to peaks of type 1 diabetes incidence.

High glucose concentration in T1D patients modulates apoptotic protein expression: down regulation of BAX and FAS and up regulation of XIAP.

UNLABELLED: Type 1 diabetes mellitus (T1D) is an autoimmune disease characterized by a progressive destruction of pancreatic ß cells. It has been reported that patients with autoimmune diseases exhibit decreased expression of caspase 3 and other pro-apoptotic markers in peripheral blood mononuclear cells (PBMC). AIM: To estimate the expression of apoptosis markers in PBMC from T1D patients cultured with high glucose concentration. RESULTS: At 11 mM of glucose, the pro-apoptotic gene fas showed a 7-fold decreased expression in the T1D group compared to controls, while bax showed a 50-fold decreased expression (medians 0.14 and 0.02, respectively, considering patients as 1). At 44 mM of glucose, there is a decreased expression of the same genes, but less abrupt (medians 0.75 and 0.47). Only the anti-apoptotic gene xiap showed a 2-fold increased expression at 11 mM of glucose (median 2.3). Regarding the clinical history, no relationships were observed with age of diagnosis, ketoacidosis, glucose at debut or GAD-65 and IA-2 titles. CONCLUSION: We can conclude that the apoptotic mechanisms in PBMC of T1D patients under high glucose conditions are altered, and this is proved by the decreased expression of the pro-apoptotic genes fas and bax and by the increased expression of the anti-apoptotic gene xiap.

Frecuencia de polimorfismo C1858T del gen PTPN22 y marcadores de autoinmunidad en pacientes chilenos con diabetes tipo 1 y enfermedad celíaca / C1858T polymorphism of protein tyrosine phosphatase, non-receptor type 22 (PTPN22) gene in diabetic and celiac patients

Background: A genetic polymorphism called C1858T of protein tyrosine phosphatase, non-receptor type 22 (PTPN22) gene has been associated with autoimmune diseases Aim: To describe the association between two autoimmune diseases, namely type 1 diabetes (T1D) and celiac disease (CD)and tyrosine phosphatase gene polymorphisms (variant C1858T of PTPN22). Subjects and Methods: C1858T single-nucleotide polymorphism within the PTPN22 gene was genotyped in 209 patients with T1D, 43 celiac patients and 100 healthy controls. Results: CC gene frequency was 0.906 and 0.790 in CD patients and controls respectively ( p < 0.01). All analyzed groups had a low frequency of the TT genotype. Compared with the other study groups, patients with T1D had a low frequency of CC genotype (0.636). Also, in these patients, there was a non-significant association between CC genotype and islet cell IA-2 auto antibodies (p < 0.065). Among CD patients, CC genotype was significantly associated with anti-transglutaminase or anti endomysial antibodies (p < 0.03). Conclusions: These results confirm the association of the genetic variant C1858T of PTPN22 with CD. In contrast to published data, this association was not found in T1D patients.

Polimorfismos del gen del receptor de muerte celular programada 1 (PDCD1) y diabetes tipo 1 en población Chilena / Programmed cell death 1 (PDCD1) gene polymorphisms and type 1 diabetes in Chilean children

Background: Programmed cell death 1 (PDCD-1) immune-receptor is a key element in the negative regulation of peripheral tolerance in T cells. Several polymorphisms of this gene have been described and it is linked with susceptibility to autoimmune diseases like Lupus and Multiple Sclerosis. Aim: To analyze four gene polymorphisms of PDCD-1 gene and explore its possible contribution as a susceptibility gene for type 1 diabetes (T1D). Patients and Methods: We analyzed 160 cases with T1D of recent diagnosis aged 9.5 ± 3.3 years and 160 control children aged 10.7 ± 3.1 years. Four genetic variants of PDCD-1 gene were studied (PD1.2; PD1.5; PD1.6 and PD1.9) by polymerase chain reaction and restriction enzymes. Autoantibodies GAD65 and anti-IA-2 were also measured in all studied children. The comparison of allelic and genotypic frequency and consistency with respect to Hardy-Weinberg equilibrium test were analyzed using Chi-square and Fisher exact test. Results: No differences between cases and controls were observed for PDCD1.2; PDCD1.5 and PDCD1.9 polymorphisms. PDCD1.6 polymorphism (carriers of allele A) had a higher frequency in the control group (0.794 versus 0.644, p < 0.017). There was no particular association of these polymorphisms with anti- GAD65 and anti-IA-2 antibodies among patients with T1D. Conclusions: Only PDCD1.6 polymorphism showed differences between T1D cases and controls. Possibly, none of these genetic variants of PDCD1 has a relevant role as a marker for T1D in the Chilean population.

[Association of GHRd3 variant of growth hormone receptor gene with autoimmunity in type 1 diabetes]. / Asociación de la variante GHRd3 del receptor de la hormona de crecimiento con autoinmunidad en la diabetes tipo 1.

BACKGROUND: Growth Hormone Receptor (GRH) is expressed in the liver, pancreas, stomach and small intestine. A high expression of GHR mRNA in the mucosal gut suggests a possible role of this receptor on digestive and immune functions. AIM: To investigate the putative effects of the GHRd3 variants on the cytokine profile and distribution of auto-antibodies in children with type 1 diabetes (T1D). MATERIAL AND METHODS: Unrelated unaffected controls (n =192) and incident cases of children with T1D (n =127) were analyzed for GHRd3 polymorphism, cytokine profile and a panel of auto-antibodies. RESULTS: The allele frequency for d3 was 24.8% in type 1 diabetics and 34.1% in controls (p =NS). Among type 1 diabetic children, the carriers of the GHRd3 polymorphism had significantly higher levels of interleukin-lB than homozygous for the wild type genotype (5.7 and 17.7, pg/ml respectively p <0.015). Carriers of d3 variant had a higher frequency of positive anti-insulin antibodies (anti-IAA) than children without this variant (39.6 and 17.7% respectively, p <0.01). CONCLUSIONS: The observed frequency of the GHR d3/d3 genotype was comparable to other reports. A relationship between d3 variant and anti-IAA antibodies and interleukin-lss was observed.

[+49 A/G genetic polymorphism of cytotoxic T lymphocyte associated antigen 4 (CTLA-4) in type 7 diabetes: association with autoantibodies and cytokines]. / Polimorfismo +49 A/G del gen del antígeno 4 del linfocito T citotóxico (CTLA-4) en la diabetes tipo 1: Asociación con el perfil de anticuerpos y citoquinas.

BACKGROUND: Cytotoxic T lymphocyte associated antigen 4 (CTLA-4) has been one ofthe non HLA genes more commonly studied in type 1 diabetes mellitus (TID). CTLA-4 is a co-stimulation protein that has a key role in the negative regulation ofT cells and is related with a functional cytokine imbalance, generating a T helper (Th) 1 over Th2 dominance. AIM: To analyze the association of +49 A/G polymorphism of CTLA-4 and its relationship with autoantibodies and cytokine expression in recently diagnosed TID patients. PATIENTS AND METHODS: CTLA-4 genetic variants and auto-antibody levéis were studied in 260 chiídren with TID and 255 healthy chiídren matched by age and gender +49 A/G polymorphism of CTLA-4 was studied by polymerase chain reaction and restriction fragmentpolymorphism (PCR-RFLP). Autoantibody levéis were measured by conventional ELISA. A panel of60 cytokines was studied simultaneously by serum array analysis in 15 TID and 15 healthy controls stratified according CTLA-4 genotype. RESULTS: The +49 A/G genetic frequency was similar in TID cases and healthy chiídren. A positive anti-GAD65 and anti-IA-2 level was observed in 673% of TID group. This percentage was increased among GG carriers (79.4% to GAD65 and 70.6% to IA-2). Finally, TID patients carrying this genotype showed a high expression of interleukin 2, 10, tumor necrosis factor alpha and interferon gamma. CONCLUSIONS: The +49 A/G polymorphism of CTLA-4 was similar in diabetic and control chiídren. Among patients with TID and carriers of GG genotype, a higher frequency of anti-GAD65 and a preferential Thl cytokine expression profile was observed.

Asociación de la variante GHRd3 del receptor de la hormona de crecimiento con autoinmunidad en la diabetes tipo 1 / Association of GHRd3 variant of growth hormone receptor gene with autoimmunity in type 1 diabetes

Background: Growth Hormone Receptor (GRH) is expressed in the liver, pancreas, stomach and small intestine. A high expression of GHR mRNA in the mucosal gut suggests a possible role of this receptor on digestive and immune functions. Aim: To investigate the putative effects of the GHRd3 variants on the cytokine profile and distribution of auto-antibodies in children with type 1 diabetes (T1D). Material and Methods: Unrelated unaffected controls (n =192) and incident cases of children with T1D (n =127) were analyzed for GHRd3 polymorphism, cytokine profile and a panel of auto-antibodies. Results: The allele frequency for d3 was 24.8 percent in type 1 diabetics and 34.1 percent in controls (p =NS). Among type 1 diabetic children, the carriers of the GHRd3 polymorphism had significantly higher levels of interleukin-lB than homozygous for the wild type genotype (5.7 and 17.7, pg/ml respectively p <0.015). Carriers of d3 variant had a higher frequency of positive anti-insulin antibodies (anti-IAA) than children without this variant (39.6 and 17.7 percent respectively, p <0.01). Conclusions: The observed frequency of the GHR d3/d3 genotype was comparable to other reports. A relationship between d3 variant and anti-IAA antibodies and interleukin-1ß was observed.

Polimorfismo +49 A/G del gen del antígeno 4 del linfocito T citotóxico (CTLA-4) en la diabetes tipo 1: Asociación con el perfil de anticuerpos y citoquinas / +49 A/G genetic polymorphism of cytotoxic T lymphocyte associated antigen 4 (CTLA-4) in type 7 diabetes: Association with autoantibodies and cytokines

Background: Cytotoxic T lymphocyte associated antigen 4 (CTLA-4) has been one ofthe non HLA genes more commonly studied in type 1 diabetes mellitus (TID). CTLA-4 is a co-stimulation protein that has a key role in the negative regulation ofT cells and is related with a functional cytokine imbalance, generating a T helper (Th) 1 over Th2 dominance. Aim: To analyze the association of +49 A/G polymorphism of CTLA-4 and its relationship with autoantibodies and cytokine expression in recently diagnosed TID patients. Patients and Methods: CTLA-4 genetic variants and auto-antibody levéis were studied in 260 chiídren with TID and 255 healthy chiídren matched by age and gender +49 A/G polymorphism of CTLA-4 was studied by polymerase chain reaction and restriction fragmentpolymorphism (PCR-RFLP). Autoantibody levéis were measured by conventional ELISA. A panel of60 cytokines was studied simultaneously by serum array analysis in 15 TID and 15 healthy controls stratified according CTLA-4 genotype. Results: The +49 A/G genetic frequency was similar in TID cases and healthy chiídren. A positive anti-GAD65 and anti-IA-2 level was observed in 673 percent of TID group. This percentage was increased among GG carriers (79.4 percent to GAD65 and 70.6 percent to IA-2). Finally, TID patients carrying this genotype showed a high expression of interleukin 2, 10, tumor necrosis factor alpha and interferon gamma. Conclusions: The +49 A/G polymorphism of CTLA-4 was similar in diabetic and control chiídren. Among patients with TID and carriers of GG genotype, a higher frequency of anti-GAD65 and a preferential Thl cytokine expression profile was observed.

Interactions between programmed death 1 (PD-1) and cytotoxic T lymphocyte antigen 4 (CTLA-4) gene polymorphisms in type 1 diabetes.

AIM: To explore the contribution of the PD-1 gene polymorphisms involved in T1D as well as the relationship between the PD-1/CTLA-4 genes and soluble CTLA-4 concentrations. PATIENTS AND METHODS: 261 incident cases of T1D and 280 healthy children less 15 years old were included in this study. Haplotypes for polymorphisms of the PD-1 and CTLA-4 genes were determined by PCR and RFLP methods. Screening for soluble CTLA-4 was done using an ELISA assay. Statistical analysis was performed using the online SHESIS package. RESULTS: Our results show that sCTLA-4 levels were higher in T1D than in controls (2.99+/-1.7 ng/ml versus 1.43+/-0.31 ng/ml, p<0.001). The allele dosage of CTLA-4 on PD-1 haplotypes, showing a significant modified effect of G carriers over AA genotype on the sCTLA-4 concentrations (5.48+/-2.09 ng/ml versus 3.27+/-1.30 ng/ml, p<0.03 in T-C haplotype) and (1.92+/-0.79 ng/ml versus 3.41+/-1.10 ng/ml, p<0.02 in C-T haplotype). CONCLUSION: Consistent with the higher serum sCTLA-4 levels observed in other autoimmune diseases, our results suggest that sCTLA-4 is elevated in T1D. Our data suggest a possible gene dosage effect of "G"CTLA-4 carriers on sCTLA-4 over the possible protective or susceptible effect conferred by PD-1 haplotypes.

Incidencia de diabetes mellitus tipo 1 en Santiago de Chile: análisis por comunas de la Región Metropolitana en el período 2000-2004 / Type 1 diabetes mellitus incidence in Santiago, Chile: Analysis by counties in the period 2000-2004

Background: There are great geographical differences in the incidence of type I diabetes mellitus. Aim: To determine the incidence rate of type 1 diabetes mellitus (DM1) in the Metropolitan Region of Santiago, Chile from January 1, 2000 to December 31, 2004 and to observe the distribution of cases in the different counties of Santiago. Material and methods: All the cases diagnosed with DM1 in the Metropolitan Region who fulfilled the following requirements were included in the study: age of onset <15 years, insulin treatment from onset, permanent residency in the area, and a diagnosis made between January, 2000 and December, 2004. Results: The incidence of DM1 was 6.58/100.000 inhabitants/year, and showed a significant increase from 2001 to 2004 (5.44 and 8.33 inhabitants/year, respectively, p <0.04). The incidence of DM1 also increased significantly in children younger than 4 years old. The incidence by counties exhibited large differences, ranging from 1,5 to 26,6/100.000 inhabitants. Counties with higher income, urbanization and low aborigine component showed a high incidence rate of type 1 diabetes. Conclusions: In the Metropolitan Region of Santiago, an increase of the incidence of DM1 has occurred in the period 2000-2004, especially in children younger than 4 years old. Large differences among counties were observed.

Prevalencia de diabetes tipo 2 y obesidad en dos poblaciones aborígenes de Chile en ambiente urbano / Prevalence of type 2 diabetes and obesity in two Chilean aboriginal populations living in urban zones

BACKGROUND: The prevalence of cardiovascular risk factors is increasing in aboriginal populations in Chile. AIM: To study the prevalence of obesity, type 2 diabetes and serum lipids in two aboriginal populations, Mapuche and Aymara, that were transferred from a rural to a urban environment. SUBJECTS AND METHODS: Two groups of subjects over 20 years were analyzed, Mapuche and Aymara. The Mapuche group was formed by 42 men and 105 women, living in four urban communities of Santiago, and an Aymara group formed by 42 men and 118 women, living in Arica, in Northern Chile. Anthropometric measurements, blood pressure, lipid profile, oral glucose tolerance test, fasting insulin and serum leptin were determined. RESULTS: The prevalence of type 2 diabetes was 6.9% in Aymara and 8.2% in Mapuche subjects. The frequency of glucose intolerance was similar in both groups, but greater among men. A total blood cholesterol over 200 mg/dl was observed in 43.1% of Aymara and 27.9% of Mapuche subjects (p <0.008). Serum triglycerides over 150 mg/dl were observed in 16.9 and 23.1% of Aymara and Mapuche individuals, respectively (p= NS). CONCLUSIONS: The prevalence of type 2 diabetes and dyslipidemia in turban aboriginal populations is higher than that of their rural counterparts. A possible explanation for these results are changes in lifestyles that come along with urbanization, characterized by a high consumption of saturated fat and refined sugars and a low level of physical activity.

Incidencia de diabetes gestacional y su relación con obesidad en embarazadas chilenas / Incidence of gestational diabetes and relationship to obesity in Chilean pregnant women

Background: Gestational diabetes (GDM) is associated to a worse outcome of pregnancy. This justifies efforts for finding possible causes of GDM that would allow implementing preventive interventions. Aim: To study incidence of GDM and its relation with obesity and other traditional risk factors. Material and methods: A retrospective study was performed in 234 women who had delivered a singleton during the last 12 months, attended in an outpatient clinic in Santiago, Chile. Familiar and personal history, body mass index (BMI), obstetrical-related pathology and data about the labor and the newborn were analyzed. Results: GDM was diagnosed in 11.2 percent of the women. BMI before pregnancy was 26.6 ± 4.4 kg/m2 (mean ± SD) and it was 25 or over in 37.8 percent of women. Women who developed GDM had significantly higher BMI in the pre-pregnancy stage and in the second and third trimester of pregnancy (p <0.001). The average age was greater in the GDM group (31±0.2 yr versus 26±0.41 yr). Incidence of GDM was 14.4 percent among women 25 years old or older and increased to 21.4 percent when they had, in addition, a BMI of 25 or over. Age, BMI, and family history of diabetes were all independently correlated with the development of GDM. Elective caesarean sections were more common in GDM than in non-GDM women (p = <0.01) and complications were present in 3/23 of newborns of women with GDM and 2/199 among women without GDM (p <0.01) Conclusions: GDM and obesity are highly prevalent in Chilean pregnant women. BMI, first degree relative with DM and age are independent risk factors for the development of GDM (Rev Méd Chile 2004; 132: 931-8).

Niveles plasmáticos de citoquinas IL-1ß, IL2 e IL-4 en niños diabéticos tipo 1 de diagnóstico reciente y su asociación con anticuerpos ß pancreáticos / Plasma levels of interleukin-1, interleukin-2 and interleukin-4 in recently diagnosed type 1 diabetic children and their association with ß-pancreatic autoantibodies

Background: Type 1 diabetes is an organ specifc autoimmune disease whose incidence is increasing worldwide. A functional imbalance in cytokine production resulting in dominance of T helper (Th1) over Th2-type response has been suggested to play a critical role in the pathogenesis of type 1 diabetes. Aim: To measure serum concentrations of interleukin (IL)-1ß, IL-2 and IL-4 in children with recently diagnosed type 1 diabetes and to evaluate the autoimmune response measuring glutamic acid decarboxylase (GAD65) and tyrosine phosphatase like (IA-2) autoantibodies. Patients and Methods: 120 diabetic children and 118 age and gender matched control children, were recruited for this study. Circulating levels of IL-1ß, IL-2 and IL-4 were measured by ELISA. GAD65 and IA-2 were measured by RIA. Results: Circulating levels of IL-1ß were elevated in type 1 diabetic children as compared to the control group (9.3±7.3 and 4.9±3.8 pg/ml respectively, p=0,01). Serum concentration of IL-2 was also higher in diabetic patients (19.8±13.1 and 11.3±9.1 pg/ml respectively, p=0,01). No differences in serum IL-4 were observed between diabetics and control. Diabetic children with one or two positive autoantibodies (IA-2 and/or GAD65) had significantly higher levels of IL-1ß and IL-2 and lower levels of IL-4 than diabetic children without positive autoantibodies. High concentrations of IL-1ß were associated with an early onset of the disease. Conclusions: High levels of IL-1ß and IL-2 were found in diabetic children with recent diagnosis of the disease. Diabetics with positive antibodies against GAD65 and IA-2 had higher levels of IL-1ß and IL-2 and lower levels of IL-4 than their counterparts without positive antibodies.

HLA y diabetes mellitus insulino-dependiente / HLA and insulin-dependent diabetes mellitus

The propensity of an individual to develop type I (insulin dependent) diabetes mellitus is directly related to specipic HLA clase II proteins, specially those from DR and DQ regions. Genetic susceptibility to insulin dependent diabetes arises from a preestablished conformation of alpha and ß chains of DQ and ß chain of DR. Since the classic demonstration by McDevitt and colleagues that DQ ß chain aspartate at position 57 was protective against the development of the disease, many populations have been surveyed to study the association between the incidence Type I diabetes and determined frequencies of DR and DQ haplotypes. The assocation between these markers and susceptibility to Type I diabetes is well established in caucasians at the present time. However, little information is available for Latin American populations, that share a mixture of european, african and native genes. Our group is studying genetic markers of three Latin American populations (Argentina, Perú and Chile) and their possible association to the different incidence of Type I diabetes mellitus in each country