Application of mixed meal tolerance tests (MMTT) to measure beta-cell function in long-term studies is limited by modification of the commercial products occurring over time. This study assessed the ...intra-individual reliability of MMTTs and compared the effects of liquid meals differing in macronutrient composition on the estimation of beta-cell function in type 2 diabetes (T2DM).
To test the reliability of MMTTs, 10 people with T2DM (age 58 ± 11 years, body mass index 30.0 ± 4.9 kg/m
) received Boost® high Protein 20 g protein three times. For comparing different meals, another 10 persons with T2DM (58 ± 5 years, 31.9 ± 5.3 kg/m
) ingested either Boost® high Protein 20 g protein or the isocaloric Boost® high Protein 15 g protein containing 35% less protein and 18% more carbohydrates. C-peptide, insulin and glucose release were assessed from the incremental area under the concentration time curve (iAUC) and the intra- and inter-individual variation of these parameters from the coefficients of variations (CV).
Repetitive ingestion of one meal revealed intra-individual CVs for the iAUCs of C-peptide, insulin and glucose, which were at least 3-times lower than the inter-individual variation of these parameters (18.2%, 19.7% and 18.9% vs. 74.2%, 70.5% and 207.7%) indicating a good reliability. Ingestion of two different meals resulted in comparable intra-individual CVs of the iAUCs of C-peptide and insulin (16.9%, 20.5%).
MMTTs provide reliable estimation of beta-cell function in people with T2DM. Furthermore, moderate differences in the protein and carbohydrate contents in a standardized liquid meal do not result in relevant changes of C-peptide and insulin responses.
Clinicaltrials.gov, Identifier number: NCT01055093. Registered 22 January 2010 - Retrospectively registered, https://www.clinicaltrials.gov/ct2/show/study/NCT01055093.
Previous studies have shown that human heat shock protein (hsp) 60 elicits a strong proinflammatory response in cells of the innate immune system with CD14, Toll-like receptor (TLR) 2, and TLR4 as ...mediators of signaling, but probably not of binding. In the present study, we directly demonstrate binding of hsp60 to the macrophage surface and find the binding receptor for hsp60 different from the previously described common receptor for several other heat shock proteins, including hsp70, hsp90, and gp96. Fluorescence-labeled human hsp60 bound to cell surfaces of the murine macrophage lines J774 A.1 and RAW264.7 and to mouse bone marrow-derived macrophages. By flow cytometry, we could demonstrate for the first time that hsp60 binding to macrophages occurred at submicromolar concentrations, is saturable, and can be competed by unlabeled hsp60, but not by unrelated proteins, thus confirming the classic characteristics of specific ligand-receptor interactions. Binding of hsp60 at 4 degrees C was followed by endocytosis at 37 degrees C. Hsp60 binding to macrophages could not be competed by excess hsp70, hsp90, or gp96, all of which share the alpha(2)-macroglobulin receptor as binding site. Hsp60 binding occurred in the absence of surface TLR4. However, no cytokine response was induced by hsp60 in TLR4-deficient macrophages. We conclude that hsp60 binds to a stereo-specific receptor on macrophages, and that different surface molecules are engaged in binding and signal transduction. Furthermore, the binding site for hsp60 is separate from the common receptor for hsp70, hsp90, and gp96, which suggests an independent role of hsp60 as danger Ag and in immunoregulation.
Aims
Restrictive exclusion criteria from different study populations may limit the generalizability of the observations. By comparing two differently designed German cohorts, we assessed the ...prevalence of cardiovascular risk factors and diabetes-related complications in recent-onset adult type 1 diabetes.
Methods
This study evaluated 1511 persons with type 1 diabetes of the prospective diabetes follow-up registry (DPV) and 268 volunteers of the prospective observational German Diabetes Study (GDS) with a known diabetes duration <1 year. Participants had similar age (36 years), sex distribution (41% female) and BMI (26 kg/m
2
) in both cohorts.
Results
The average HbA1c was 6.4 ± 0.8% in the GDS and 7.0 ± 1.1% in the DPV. Prevalence of hypertension (24%) was similar, while more DPV participants had dyslipidemia and lipid-lowering medication than GDS participants (77% vs. 41% and 7% vs. 2%, respectively; p<0.05). Prevalence of retinopathy and nephropathy was higher in DPV compared to GDS participants (10% vs. 3% and 18% vs. 7%, respectively; p<0.001).
Conclusions
Diabetic nephropathy and retinopathy are the most frequent complications in type 1 diabetes, affecting up to every 10th patient within the first year after diagnosis, underlining the need for more stringent risk factor management already at the time of diagnosis of type 1 diabetes.
Mammalian 60-kDa heat-shock protein (hsp60) is a key target of T cell and Ab responses in chronic inflammation or atherosclerosis. We show in this study that human hsp60 is also an Ag recognized by ...cells of the innate immune system, such as macrophages. Both mouse and human macrophages respond to contact with exogenous human hsp60 with rapid release of TNF-alpha; mouse macrophages in addition produce nitric oxide. The proinflammatory macrophage response is hsp60 dose dependent and similar in kinetics and extent to LPS stimulation. Human hsp60 was found to synergize with IFN-gamma in its proinflammatory activity. Finally, human hsp60 induces gene expression of the Th1-promoting cytokines IL-12 and IL-15. These findings identify autologous hsp60 as a danger signal for the innate immune system, with important implications for a role of local hsp60 expression/release in chronic Th1-dependent tissue inflammation.
The rs540467 SNP in the
gene, encoding a mitochondrial complex I subunit, has been shown to modulate adaptations to exercise training. Interaction effects with diabetes mellitus remain unclear. We ...assessed associations of habitual physical activity (PA) levels with metabolic variables and examined a possible modifying effect of the rs540467 SNP. Volunteers with type 2 (n=242), type 1 diabetes (n=250) or normal glucose tolerance (control; n=139) were studied at diagnosis and subgroups with type 1 (n=96) and type 2 diabetes (n=95) after 5 years. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamps, oxygen uptake at the ventilator threshold (VO
AT) by spiroergometry and PA by questionnaires. Translational studies investigated insulin signaling and mitochondrial function in
siRNA-treated C2C12 myotubes, with electronic pulse stimulation (EPS) to simulate exercising. PA levels were 10 and 6%, VO
AT was 31% and 8% lower in type 2 and type 1 diabetes compared to control. Within 5 years, 36% of people with type 2 diabetes did not improve their insulin sensitivity despite increasing PA levels. The
rs540467 SNP modifies PA-mediated changes in insulin sensitivity, body composition and liver fat estimates in type 2 diabetes. Silencing
in myotubes reduced mitochondrial respiration and prevented rescue from palmitate-induced insulin resistance after EPS. A substantial proportion of humans with type 2 diabetes fails to respond to rising PA with increasing insulin sensitivity. This may at least partly relate to a polymorphism of the
gene, which may contribute to modulating mitochondrial function.
ClinicalTrials.gov, identifier NCT01055093. The trial was retrospectively registered on 25
of January 2010.
To investigate the associations of a lifestyle score with various cardiovascular risk markers, indicators for fatty liver disease as well as MRI-determined total, subcutaneous and visceral adipose ...tissue mass in adults with new-onset diabetes.
This cross-sectional analysis included 196 individuals with type 1 (median age: 35 years; median body mass index (BMI): 24 kg/m²) and 272 with type 2 diabetes (median age: 53 years; median BMI: 31 kg/m²) from the German Diabetes Study. A healthy lifestyle score was generated based on healthy diet, moderate alcohol consumption, recreational activity, non-smoking and non-obese BMI. These factors were summed to form a score ranging from 0 to 5. Multivariable linear and non-linear regression models were used.
In total, 8.1% of the individuals adhered to none or one, 17.7% to two, 29.7% to three, 26.7% to four, and 17.7% to all five favorable lifestyle factors. High compared with low adherence to the lifestyle score was associated with more favorable outcome measures, including triglycerides (β (95% CI) -49.1 mg/dL (-76.7; -21.4)), low-density lipoprotein (-16.7 mg/dL (-31.3; -2.0)), and high-density lipoprotein cholesterol (13.5 mg/dL (7.6; 19.4)), glycated hemoglobin (-0.5% (-0.8%; -0.1%)), high-sensitivity C reactive protein (-0.4 mg/dL (-0.6; -0.2)), as well as lower hepatic fat content (-8.3% (-11.9%; -4.7%)), and visceral adipose tissue mass (-1.8 dm³ (-2.9; -0.7)). The dose-response analyses showed that adherence to every additional healthy lifestyle factor was associated with more beneficial risk profiles.
Adherence to each additional healthy lifestyle factor was beneficially associated with cardiovascular risk markers, indicators of fatty liver disease and adipose tissue mass. Strongest associations were observed for adherence to all healthy lifestyle factors in combination.
NCT01055093.
It is still an enigma why T cell autoreactivity in type 1 diabetes targets few beta cell antigens only. Among these, one primary autoantigen is pro(insulin). Autoimmune T cells preferentially ...recognise three epitopes on the proinsulin molecule, of which the peptide region B:11-23 is the dominant one. Interestingly, the three regions superimpose with binding sites of the chaperone hsp70, the region B:11-23 being the strongest binding one. Absence of an intact core region B:15-17 prevents autoimmune diabetes in NOD as well as binding of hsp70. A role of hsp70 in selecting autoimmune epitopes is supported by the ability of this and other chaperones to deliver bound peptides to MHC class I and II molecules for efficient antigen presentation. Binding of hsp70 to receptors on antigen presenting cells such as TLR4 results in costimulatory signals for T cell activation. Strongest effects are seen for the mixture of hsp70 with the peptide B:11-23. Thus, hsp70 may assist in proinsulin epitope selection and efficient presentation to autoreactive T cells. The concept of chaperone guided immune reactivity may also apply to other autoimmune diseases.
•(Pro)insulin is one primary antigen in type 1 diabetes.•T cell reactive proinsulin epitopes also bind to chaperone hsp70/DnaK.•Hsp70 can transfer peptides to MHC molecules.•Hsp70 and other chaperones may promote autoimmunity to selected antigens.•Legends to figures.
BCG vaccination affects other diseases beyond tuberculosis by unknown-potentially immunomodulatory-mechanisms. Recent studies have shown that BCG vaccination administered during overt type 1 diabetes ...(T1D) improved glycemic control and affected immune and metabolic parameters. Here, we comprehensively characterized Ghanaian T1D patients with or without routine neonatal BCG vaccination to identify vaccine-associated alterations. Ghanaian long-term T1D patients (
= 108) and matched healthy controls (
= 214) were evaluated for disease-related clinical, metabolic, and immunophenotypic parameters and compared based on their neonatal BCG vaccination status. The majority of study participants were BCG-vaccinated at birth and no differences in vaccination rates were detected between the study groups. Notably, glycemic control metrics, i.e., HbA1c and IDAA1c, showed significantly lower levels in BCG-vaccinated as compared to unvaccinated patients. Immunophenotype comparisons identified higher expression of the T cell activation marker CD25 on CD8
T cells from BCG-vaccinated T1D patients. Correlation analysis identified a negative correlation between HbA1c levels and CD25 expression on CD8
T cells. In addition, we observed fractional increases in glycolysis metabolites (phosphoenolpyruvate and 2/3-phosphoglycerate) in BCG-vaccinated T1D patients. These results suggest that neonatal BCG vaccination is associated with better glycemic control and increased activation of CD8
T cells in T1D patients.
Background. Heat shock proteins (Hsp) act as intracellular chaperones and in addition are used as adjuvant in vaccines of peptides complexed with recombinant Hsp. By interacting with autologous ...peptides, Hsp may promote the induction of autoimmune reactivity. Objective. Here, we analysed whether the effect of Hsp on macrophages is modulated by insulin peptides known to interact with Hsp. Results. Combinations of the 70 kDa Hsp DnaK with peptide B11-23 from the core region of the proinsulin B-chain induced the release of the inflammatory mediators interleukin-6, tumor necrosis factor α, and interleukin-1β from cells of human and murine macrophage lines. In parallel, there was high-affinity binding of B11-23 to DnaK. DnaK mixed with peptides from other regions of the insulin molecule did not stimulate cytokine secretion. DnaK alone induced little cytokine production, and peptides alone induced none. Conclusion. The macrophage-stimulating potential of Hsp70 family proteins when combined with the proinsulin B-chain peptide B11-23 may contribute to the immunodominance of this peptide in the development of beta cell-directed autoimmunity in type 1 diabetes.
Diabetes mellitus has been associated with impaired cognitive performance, particularly in verbal memory. Mediterranean diets (MedD) may lead to improvements in overall and single cognitive ...functions. We hypothesised that adherence to MedD associates with better performance in verbal memory in patients with type 1 or type 2 diabetes. Thus, we performed a cross-sectional analysis including patients with recently diagnosed type 1 (n = 75) or type 2 diabetes (n = 118), metabolically healthy individuals (n = 41) and individuals with type 1 (n = 44) or type 2 diabetes (n = 62) of at least five years after diagnosis. Participants underwent comprehensive metabolic phenotyping and cognitive testing. Adherence to the Modified Mediterranean diet scale (MMDS) was computed from a food frequency questionnaire. Among patients with type 2 diabetes with a known diabetes duration ≥5 years, closer adherence to the MMDS was associated with higher score in verbal memory after adjustment for potential confounders (P = 0.043). Adherence to the MMDS did not relate to verbal memory in recently diagnosed type 2 diabetes (P = 0.275), recently diagnosed or longer-standing type 1 diabetes (P = 0.215 and P = 0.626, respectively) or metabolically healthy individuals (P = 0.666). In conclusion, closer adherence to MedD may exert beneficial effects on cognitive performance in the course of type 2 diabetes.
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