Immunoregulatory differences between adult onset type 1 diabetes and latent autoimmune diabetes in adults (LADA)

Autoimmune diabetes is characterized by cell mediated autoimmunity against insulin producing beta cells in pancreatic islets. Type 1 diabetes is the major cause of diabetes in children and adolescents and is believed to be mediated by a Thl driven destruction of beta cells. The much more prevalent type 2 diabetes is not considered as an autoimmune disease but diabetes specific autoantibodies (ICA or GADA) are found in 5-15% of the cases. These subjects are referred to as latent autoimmune diabetes in adults (LADA). It has been questioned if LADA is a unique entity or should be considered as type 1 diabetes. Subjects with LADA have a better preserved insulin secretion and a slower progression to beta cell failure at clinical onset compared to subjects with type 1 diabetes. Furthermore, there are adult onset type 1 diabetic patients that share the rapid progression to beta cell failure with juvenile onset diabetes. The hypothesis was therefore that type 1 diabetes and LADA have different autoimmune activity. The aim was to identify some of the immunoregulatory events that could explain differences in disease progression between the groups. Heterozygosity of the diabetes associated high risk HLA haplotypes DR3/DQ2-DR4/DQ8 was considered as a risk factor for both adult onset type 1 diabetes and LADA. Also homozygosity for the microsatellite marker TNFa2 conferred an increased risk for both type 1 diabetes and LADA even though this was probably due to linkage disequilibrium with the HLA haplotypes. However, presence of either one of HLA DR3/DQ2 or DR4/DQ8 conferred an increased risk of type 1 diabetes but not LADA. Autoantibodies directed against glutamic acid decarboxylase 65 (GADA) were predominantly of the IgGl subclass in both adult onset type 1 diabetes and LADA. Moreover, the IgG4 subclass was the second most common subclass in LADA but below detection limit in type 1 diabetes at clinical onset. This suggests a larger involvement of Th2 cells in LADA compared to in type 1 diabetes. The levels of all the GADA IgG subclasses decreased in type 1 diabetes three years after clinical onset while LADA remained their subclass profiles indicating a sustained difference in autoimmune response against the beta cell antigen GAD65 between the groups. The slower progression of beta cell failure in LADA might be due to a more balanced T cell response that reduces the cytotoxic Thl cell mediated response. Type 1 diabetes and LADA could thus be considered as different variations of autoimmunity

IgG4 subclass glutamic acid decarboxylase antibodies (GADA) are associated with a reduced risk of developing type 1 diabetes as well as increased C-peptide levels in GADA positive gestational diabetes.

Some women with gestational diabetes (GDM) present with autoantibodies associated with type 1 diabetes. These are usually directed against glutamic acid decarboxylase (GADA) and suggested to predict development of type 1 diabetes. The primary aim of this study was to investigate if GADA IgG subclasses at onset of GDM could assist in predicting postpartum development. Of 1225 women diagnosed with first-time GDM only 51 were GADA-positive. Total GADA was determined using ELISA. GADA subclasses were determined with radioimmunoassay. Approximately 25% of GADA-positive women developed type 1 diabetes postpartum. Titers of total GADA were higher in women that developed type 1 diabetes (142.1 vs 74.2u/mL; p=0.04) and they also had lower titers of GADA IgG4 (index=0.01 vs 0.04; p=0.03). In conclusion we found that that women with high titers of total GADA but low titers of GADA IgG4 were more prone to develop type 1 diabetes postpartum

Soluble urokinase-plasminogen activator receptor (suPAR) and natural phosphorylcholine IgM antibodies in patients at clinical onset of diabetes mellitus

We have studied the presence of novel inflammatory markers as soluble urokinase plasminogen activator receptor (suPAR) and natural IgM antibodies directed against phosphorylcholine (αPC-IgM) in Swedish diabetic patients (n = 164) and in healthy control subjects (n = 41). SuPAR is expressed by several types of immune cells and has been shown to be a marker of disease severity and predict mortality during infections. It has also been associated with low-grade inflammation. High levels of αPC-IgM have been shown to negatively associate with the risk of cardiovascular disease and vascular inflammation. This has been suggested to be more common among diabetic patients than in the background population. The patients were 15-34 years of age and were included in the diabetes incidence study in Sweden (DISS). They were all clinically diagnosed to have either T1D (n = 82) or T2D (n = 82). All subjects were matched in gender and age. Commercially available ELISA was used to detect suPAR and αPC-IgM. We found that suPAR levels were higher in diabetic patients (n = 164, Q2 = 4.5 mg/L) compared to in healthy control subjects (n = 41, Q2 = 2.7 mg/L; p < 0.0001), and in patients classified with T2D (n = 82; Q2 = 4.9) compared to in patients classified with T1D (n = 82; p=0.0002). The difference between T2D and T1D was even more obvious when LADA (n = 17) was extracted from the T2D group. SuPAR levels did also correlate with BMI (rs = 0.50; p < 0.0001), C-peptide levels (rs = 0.23; p < 0.0001) and CRP (rs = 0.58; p < 0.0001). Titers of αPC-IgM did not significantly differ between patients and controls. This is the first study to show the difference in suPAR levels between T1D and T2D patients. The high levels of suPAR in T2D patients indicate a strong activation of the immune system and its relation to disease progression needs to be further investigated. However, our data do not support a role for αPC-IgM in the development of diabetes

Determination of glutamic acid decarboxylase antibodies (GADA) IgG subclasses - comparison of three immunoprecipitation assays (IPAs)

IgG subclasses of glutamic acid decarboxylase (GAD(65)) antibodies (GADA) may reflect the immunological state in the pancreas of GADA-positive patients with autoimmune diabetes. The use of biotin-conjugated antibodies and streptavidin Sepharose are used commonly in immunoprecipitation assays (IPA) based on (125)I- or (35)S-labelled antigens to capture IgG subclasses directed against IA-2 or GAD(65). We have compared three different immunoprecipitation assays for the determination of GADA IgG subclasses. Two of the assays were based on the biotin and streptavidin systems provided in a solid (immobilized) or liquid (mobilized) phase binding environment. The third assay was based on N-hydroxysuccinimide (immobilized) interaction with primary amines (i.e. lysine residues) on the antibody. We found the liquid phase binding assay (LPBA) to be the most stable assay, with a comparatively low coefficient of variation and background

Low levels of soluble TWEAK, indicating on-going inflammation, were associated with depression in type 1 diabetes : a cross-sectional study

Background: Low levels of the soluble tumour necrosis factor-like weak inducer of apoptosis (sTWEAK) and depression are linked to cardiovascular disease. Galectin-3, inadequate glycemic control and low high-density lipoprotein (HDL)-cholesterol levels were previously linked to depression in these patients with type 1 diabetes mellitus (T1DM). The main aim was to explore whether sTWEAK was associated with depression. A secondary aim was to explore diabetes related variables associated with low sTWEAK. Methods: Cross-sectional design. T1DM patients (n = 283, men 56%, age18–59 years) were consecutively recruited from one specialist diabetes clinic. Depression was defined as Hospital Anxiety and Depression Scale-Depression sub scale ≥8 points. Blood samples, anthropometrics and blood pressure were collected, supplemented with data from electronic health records. Enzyme linked immunosorbent assays were used to measure sTWEAK and galectin-3. Low sTWEAK was defined as < 7.2 ng/ml and high galectin-3 as ≥2.6 ng/ml. Multiple logistic regression analyses were performed, calibrated and validated for goodness of fit. We adjusted for age, sex, diabetes duration, galectin-3, metabolic variables, serum-creatinine, smoking, physical inactivity, medication, and cardiovascular complications. Results: For 29 depressed versus 254 non-depressed patients the prevalence rates were for low sTWEAK: 93 and 68% (p = 0.003) and for high galectin-3: 34 and 13% (p = 0.005) respectively. HDL-cholesterol levels were lower for the depressed (p = 0.015). Patients with low sTWEAK versus high sTWEAK had lower usage of continuous subcutaneous insulin infusion (CSII) (6% versus 17%, p = 0.005). Low sTWEAK (adjusted odds ratio (AOR) 9.0, p = 0.006), high galectin-3 (AOR 6.3, p = 0.001), HDL-cholesterol (per mmol/l) (AOR 0.1, p = 0.006), use of antidepressants (AOR 8.4, p < 0.001), and age (per year) (AOR 1.05, p = 0.027) were associated with depression. CSII (AOR 0.3, p = 0.003) and depression (AOR 7.1, p = 0.009) were associated with low sTWEAK. Conclusions: Lower levels of sTWEAK and HDL-cholesterol and higher levels of galectin-3 were independently associated with depression in T1DM. These factors might all contribute to the increased risk for cardiovascular disease and mortality previously demonstrated in patients with depression. CSII (inversely) and depression were independently associated with low sTWEAK levels

Higher levels of the soluble receptor for advanced glycation end products and lower levels of the extracellular newly identified receptor for advanced glycation end products were associated with lipid-lowering drugs in patients with type 1 diabetes : a comparative cross-sectional study

Background: The receptors for advanced glycation end products (RAGE) are increased in atherosclerotic plaques. Soluble (s)RAGE decreases, whereas the extracellular newly identified receptor for advanced glycation end products (EN-RAGE) increases inflammatory responses mediated by RAGE. The aims were to explore whether sRAGE, EN-RAGE and the EN-RAGE/sRAGE ratio, were associated with the use of lipid-lowering drugs (LLD) and/or antihypertensive drugs (AHD) in patients with type 1 diabetes (T1D). Methods: Cross-sectional design. T1D patients were consecutively recruited from one diabetes clinic. Blood samples were collected, supplemented with data from electronic health records. sRAGE and EN-RAGE were analysed by enzyme linked immunosorbent assays. An EN-RAGE/sRAGE ratio was calculated. Adjustments were performed with inflammatory and metabolic variables, s-creatinine, depression, smoking, physical inactivity, medication, and cardiovascular complications. Multiple regression analyses were performed. Results: In this study 283 T1D patients (men 56%, 18–59 years) were included. One-hundred and thirty LLD users compared to 153 non-users had lower levels of the EN-RAGE/sRAGE ratio (P = 0.009), and 89 AHD users compared to 194 non-users had lower levels of sRAGE (P = 0.031). The use of LLD (inversely) (B coefficient − 0.158, P = 0.033) and the use of AHD (B coefficient 0.187, P = 0.023) were associated with the EN-RAGE/sRAGE ratio. sRAGE (Lg10) (per unit) (adjusted odds ratio (AOR) = 3.5, 95% CI = 1.4–9.1, P = 0.009), EN-RAGE (Lg10) (per unit) (inversely) (AOR 0.4, 95% CI = 0.2–1.0, P = 0.046), age (P < 0.001), and triglycerides (P < 0.029), were associated with LLD. sRAGE (Lg10) (per unit) (inversely) (AOR = 0.2, 95% CI = 0.1–0.5, P = 0.001), diabetes duration, triglycerides, s-creatinine, and systolic BP (all P values < 0.043), were associated with AHD. Conclusions: Higher sRAGE levels and lower EN-RAGE levels were linked to the use of LLD, whereas lower sRAGE levels were linked to the use of AHD. No other variables but the use of LLD and the use of AHD were linked to the EN-RAGE/sRAGE ratio. This may be of major importance as sRAGE is an inhibitor and EN-RAGE is a stimulator of inflammatory processes mediated by RAGE