Plasma heat shock protein response to euglycemia in type 2 diabetes

Changes of the salivary and serum proteome in canine hypothyroidism

In this study, changes in salivary and serum proteome of dogs with hypothyroidism were studied using tandem mass tags (TMT) labelling and liquid chromatography-mass spectrometry (LC-MS/MS). Saliva and serum proteome from 10 dogs with hypothyroidism were compared with 10 healthy dogs. In saliva, a total of seven proteins showed significant changes between the two groups, being six downregulated and one upregulated, meanwhile, in serum, a total of six proteins showed significant changes, being five downregulated and one upregulated. The altered proteins reflected metabolic and immunologic changes, as well as, skin and coagulation alterations, and these proteins were not affected by gender. One of the proteins that were downregulated in saliva, lactate dehydrognease (LDH), was measured by a spectrophotometric assay in saliva samples from 42 dogs with hypothyroidism, 42 dogs with non-thyroid diseases and 46 healthy dogs. The activity of LDH was lower in the saliva of hypothyroid dogs when compared to non-thyroid diseased dogs and healthy controls. This study indicates that canine hypothyroidism can produce changes in the proteome of saliva and serum. These two sample types showed different variations in their proteins reflecting physiopathological changes that occur in this disease, mainly related to the immune system, metabolism, skin and coagulation. In addition, some of the proteins identified in this study, specially LDH in saliva, should be further explored as potential biomarkers of canine hypothyroidism.

The role of heat shock proteins (HSPs) in type 2 diabetes mellitus pathophysiology

Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by sustained hyperglycemia caused by impaired insulin signaling and secretion. Metabolic stress, caused by an inappropriate diet, is one of the major hallmarks provoking inflammation, endoplasmic reticulum (ER) stress, and mitochondrial dysfunction. Heat shock proteins (HSPs) are a group of highly conserved proteins that have a crucial role in chaperoning damaged and misfolded proteins to avoid disruption of cellular homeostasis under stress conditions. To do this, HSPs interact with diverse intra-and extracellular pathways among which are the insulin signaling, insulin secretion, and apoptosis pathways. Therefore, HSP dysfunction, e.g. HSP70, may lead to disruption of the pathways responsible for insulin secretion and uptake. Consistently, the altered expression of other HSPs and genetic polymorphisms in HSP-producing genes in diabetic subjects has made HSPs hot research in T2DM. This paper provides a comprehensive overview of the role of different HSPs in T2DM pathogenesis, affected cellular pathways, and the potential therapeutic strategies targeting HSPs in T2DM.

MicroRNA Changes Up to 24 h following Induced Hypoglycemia in Type 2 Diabetes

Hypoglycemia, as a complication of type 2 diabetes (T2D), causes increased morbidity and mortality but the physiological response underlying hypoglycemia has not been fully elucidated. Small noncoding microRNA (miRNA) have multiple downstream biological effects. This pilot exploratory study was undertaken to determine if induced miRNA changes would persist and contribute to effects seen 24 h post-hypoglycemia. A parallel, prospective study design was employed, involving T2D (n = 23) and control (n = 23) subjects. The subjects underwent insulin-induced hypoglycemia (2 mmol/L; 36 mg/dL); blood samples were drawn at baseline, upon the induction of hypoglycemia, and 4 h and 24 h post-hypoglycemia, with a quantitative polymerase chain reaction analysis of miRNA undertaken. The baseline miRNAs did not differ. In the controls, 15 miRNAs were downregulated and one was upregulated (FDR < 0.05) from the induction of hypoglycemia to 4 h later while, in T2D, only four miRNAs were altered (downregulated), and these were common to both cohorts (miR-191-5p; miR-143-3p; let-7b-5p; let-7g-5p), correlated with elevated glucagon levels, and all were associated with energy balance. From the induction of hypoglycemia to 24 h, 14 miRNAs were downregulated and 5 were upregulated (FDR < 0.05) in the controls; 7 miRNAs were downregulated and 7 upregulated (FDR < 0.05) in T2D; a total of 6 miRNAs were common between cohorts, 5 were downregulated (miR-93-5p, let-7b-5p, miR-191-5p, miR-185-5p, and miR-652-3p), and 1 was upregulated (miR-369-3p). An ingenuity pathway analysis indicated that many of the altered miRNAs were associated with metabolic and coagulation pathways; however, of the inflammatory proteins expressed, only miR-143-3p at 24 h correlated positively with tumor necrosis factor-α (TNFa; p < 0.05 and r = 0.46) and negatively with toll-like receptor-4 (TLR4; p < 0.05 and r = 0.43). The MiRNA levels altered by hypoglycemia reflected changes in counter-regulatory glucagon and differed between cohorts, and their expression at 24 h suggests miRNAs may potentiate and prolong the physiological response. Trial registration: ClinicalTrials.gov NCT03102801.

Serum Level of Heat Shock Protein 70 in Patients with Type 2 Diabetes Mellitus in Basrah, Iraq

Diabetes mellitus is a chronic metabolic disease with an increasing prevalence, caused by a defect in insulin production, insulin action, or both, and can increase the risk for the development of microvascular as well as macrovascular complications. Heat shock protein70 is considered a family of a larger group of proteins known as heat shock proteins, which their expression is induced when the cells are subjected to environmental stress. They are believed to keep the native folding of proteins in cells under stressful conditions and their therapeutic role. Therefore, this study aimed to investigate the serum level of HSP70 in patients with type 2 diabetes mellitus (T2DM) to assess if there is an association of HSP70 with T2DM and to evaluate the effect of age and duration of disease on the serum level of HSP70. Ninety-one patients with T2DM were recruited, and 85 individuals with the same age range and sex as healthy controls. Serum HSP70, fasting blood sugar, and HbA1c were measured. The results revealed that the level of HSP70 was significantly higher in the diabetic group compared to the control group (P value<0.05). The level of HSP70 showed a significant positive correlation with age and duration of disease as well as with fasting blood sugar and HbA1c. The study suggested that HSP70 may have the potential to be used as an indicator of metabolic derangement and a prognostic biomarker in diabetes.

Severe iatrogenic hypoglycaemia modulates the fibroblast growth factor protein response

INTRODUCTION

There is evidence that fibroblast growth factor (FGF) levels may be implicated in hypoglycaemia, with FGF19 being a potential contributor to insulin-independent pathways driving postprandial hypoglycaemia following bariatric surgery and basic FGF (FGF2) being elevated following mild hypoglycaemia occurring after the glucose tolerance test. However, their response following severe iatrogenic hypoglycaemia is unknown and therefore this pilot exploratory study was undertaken.

METHODS

A case-control study of aged-matched type 2 diabetes (T2D; n = 23) and control (n = 23) subjects who underwent a hyperinsulinaemic clamp, initially to euglycaemia in T2D (5 mmol/L; 90 mg/dl), and then to hypoglycaemia (<2 mmol/L; <36 mg/dl) with subsequent follow-up time course to 24 h. FGF and FGF receptor proteins were determined by Slow Off-rate Modified Aptamer (SOMA)-scan plasma protein measurement.

RESULTS

At baseline, FGF12 (p = .006) was higher and FGF20 (p = .004) was lower in T2D versus controls. At hypoglycaemia, FGF7 was lower in T2D. Post-hypoglycaemic levels of FGF18, FGF19, FGF20 and FGF23 were lower while FGF12 and FGF16 were higher in T2D versus control at different time points. No differences between T2D and controls were seen for FGF1, FGF2, FGF4, FGF6, FGF8, FGF9, FGF10, FGF21 or any of the FGF receptors. At 24 h post-hypoglycaemia, FGF20 (p = .01) differed between controls and T2D, while the levels for the other proteins measured returned to baseline. None of the FGF proteins altered from baseline to euglycaemia when clamped in T2D subjects. FGF23 negatively correlated with fasting blood glucose, but no FGFs correlated with body mass index in T2D.

CONCLUSION

Severe transient hypoglycaemia modulated FGF7, 16, 19, 20 and 23 (known to be associated with diabetes), together with FGF18 and 12, not previously reported to be associated with diabetes but that may be important in the pathophysiology of hypoglycaemia; FGF20 remained low at 24 h. Taken together, these data suggest that recurrent hypoglycaemia may contribute to the development of complications through changes in FGF proteins.

The Protective Effect of UBE2G2 Knockdown Against Atherosclerosis in Apolipoprotein E-Deficient Mice and Its Association with miR-204-5p

Atherosclerosis (AS) is a chronic and progressive inflammatory disease. Ubiquitin-conjugating enzyme E2G 2 (UBE2G2) has been reported to be differentially expressed in subjects with abnormal coronary endothelial function. We intended to further explore the effect of UBE2G2 in AS using apolipoprotein E-deficient (ApoE^-/-) mice. Relative UBE2G2 expression in aortic sinus tissues was examined by Real-time reverse transcriptase-polymerase chain reaction and immunohistochemical staining. Atherosclerotic plaque formation was observed through hematoxylin-eosin staining. The protein levels of adhesion biomarkers and inflammatory cytokines was analyzed by western blotting. The direct interaction between UBE2G2 and miR-204-5p was predicted by bioinformatic analysis, and the correlation was analyzed by Pearson's correlation test, and verified by luciferase reporter assay. Human vascular smooth muscle cells (VSMCs) development was detected by 5-ethynyl-2'-deoxyuridine labeling assay and wound healing assays. UBE2G2 was highly expressed in the aortic sinus tissues of high-fat diet-fed ApoE^-/- mice. The atherosclerotic plaque formation was increased in ApoE^-/- mice, while UBE2G2 knockdown reduced it. Silencing of UBE2G2 also inhibited the expression and protein levels of adhesion biomarkers and inflammatory cytokines in ApoE^-/- mice. MiR-204-5p was the upstream effector of UBE2G2 and miR-204-5p overexpression was found to inhibit the proliferation and migration of human VSMCs through regulating UBE2G2 expression. UBE2G2 inhibition attenuated AS in ApoE^-/- mice and UBE2G2 expression was negatively regulated by miR-204-5p in human VSMCs.

MiRNA and associated inflammatory changes from baseline to hypoglycemia in type 2 diabetes

OBJECTIVE

Hypoglycemia in type 2 diabetes (T2D) increases morbidity and mortality but the underlying physiological response is still not fully understood, though physiological changes are still apparent 24 hours after the event. Small noncoding microRNA (miRNA) have multiple downstream biological effects that may respond rapidly to stress. We hypothesized that hypoglycemia would induce rapid miRNA changes; therefore, this pilot exploratory study was undertaken.

METHODS

A pilot prospective, parallel study in T2D (n=23) and controls (n=23). Insulin-induced hypoglycemia (2mmol/l: 36mg/dl) was induced and blood sampling performed at baseline and hypoglycemia. Initial profiling of miRNA was undertaken on pooled samples identified 96 miRNA that were differentially regulated, followed by validation on a custom designed 112 miRNA panel.

RESULTS

Nine miRNAs differed from baseline to hypoglycemia in control subjects; eight were upregulated: miR-1303, miR-let-7e-5p, miR-1267, miR-30a-5p, miR-571, miR-661, miR-770-5p, miR-892b and one was downregulated: miR-652-3p. None of the miRNAs differed from baseline in T2D subjects.

CONCLUSION

A rapid miRNA response reflecting protective pathways was seen in control subjects that appeared to be lost in T2D, suggesting that mitigating responses to hypoglycemia with blunting of the counter-regulatory response in T2D occurs even in patients with short duration of disease.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT03102801?term=NCT03102801&draw=2&rank=1, identifier NCT03102801.

Heat Shock-Related Protein Responses and Inflammatory Protein Changes Are Associated with Mild Prolonged Hypoglycemia

Mild hypoglycemia is common in clinical practice. Severe hypoglycemia results in heat shock protein and associate co-chaperone changes. Whether mild prolonged hypoglycemia elicits a similar response with inflammatory and oxidative-stress responses compared with a severe hypoglycemic event is unclear; therefore, this pilot exploratory study was undertaken. We performed a case–control induced hypoglycemia clamp study, maintaining blood glucose at 2.8 mmol/L (50 mg/dL) for 1 h in 17 subjects (T2D (n = 10); controls (n = 7)). Blood sampling was performed at baseline, hypoglycemia, and 24 h; slow off-rate modified aptamer (SOMA)-scan plasma protein analysis of HSP-related proteins, inflammatory stress markers, and oxidative stress markers was performed. In total, 16 HSPs were analyzed. At baseline, TLR4:MD-2 complex was elevated (p = 0.01), whilst HSPA8 was lower (p < 0.05) in T2D. At hypoglycemia, UBE2N, STIP1, and UBE2L3 increased (all p < 0.05), whilst TLR4:MD-2 and HSPA8 decreased (p < 0.05) in T2D versus baseline. In follow-up after hypoglycemia, HSPs normalized to baseline by 24 h, except UBE2L3 (p < 0.05), which was decreased in controls versus baseline. Correlation of altered inflammatory markers with HSPs revealed the following: at baseline, TLR4:MD-2 correlated with CXCL10 (p < 0.01) and SIGLEC1 (p < 0.05) in controls; HSPA8 negatively correlated with IL5 (p < 0.05) in T2D. A negative correlation between urinary isoprostane 8-iso PGF2α, a marker of oxidative stress, and HSPA1A was seen at 24 h in T2D only (p < 0.05). In conclusion, the HSP changes seen for mild prolonged hypoglycemia were similar to those previously reported for a severe event. However, mild prolonged hypoglycemia appeared to elicit an increased inflammatory response that was associated with heat shock and related proteins.

Impact of severe hypoglycemia on the heat shock and related protein response

Heat shock proteins contribute to diabetes-induced complications and are affected by glycemic control. Our hypothesis was that hypoglycemia-induced heat shock and related protein changes would be amplified in type 2 diabetes (T2D). This prospective, case-control study enrolled 23 T2D patients and 23 control subjects who underwent hyperinsulinemic-induced hypoglycemia (≤ 2.0 mmol/L (36 mg/dl)) with blood sampling at baseline, at hypoglycemia and after a 24-h post-hypoglycemia follow-up period. Proteomic analysis of heat shock-related and pro-inflammatory proteins was performed. At baseline, MAPKAPK5 (p = 0.02) and UBE2G2 (p = 0.003) were elevated and STUB1 decreased (p = 0.007) in T2D. At hypoglycemia: PPP3CA (p < 0.03) was increased and EPHA2 (p = 0.01) reduced in T2D; by contrast, three proteins were reduced in controls [HSPA1A (p = 0.007), HSPB1 (p < 0.02), SMAD3 (p = 0.005)] while only MAPKAPK5 was elevated (p = 0.02). In the post-hypoglycemia follow-up period, most proteins normalized to baseline by 24-h; however, STIP1 (p = 0.003), UBE2N (p = 0.004) and UBE2L3 (p < 0.04) were decreased in controls at 24-h. No protein differed from baseline at 24-h in T2D. Pro-inflammatory interleukin-6 increased at 4-h post-hypoglycemia in controls and T2D (p < 0.05 and p < 0.003, respectively) and correlated with HSPA1A; anti-inflammatory IL-10 decreased 2-h post-hypoglycemia in T2D only. Other pro-inflammatory proteins, IL-1α, IFN-γ and TNF-α, were unchanged. Heat shock and related proteins differed at baseline between T2D and controls, with an exaggerated response of heat shock and related proteins to hypoglycemia that returned to baseline, though with changes at 24-h in controls alone. An increase in pro-inflammatory IL-6, with a decrease in anti-inflammatory IL-10, suggests that the HSP system is overactivated due to underlying inflammation in T2D.Trial registration: ClinicalTrials.gov NCT03102801.