Type 1 diabetes alters ischemia-induced gene expression

Novel components in the nuclear factor-kappa B (NF-κB) signaling pathways of endothelial cells under hyperglycemic-ischemic conditions

Diabetes worsens the outcomes of a number of vascular disorders including peripheral arterial disease (PAD) at least in part through induction of chronic inflammation. However, in experimental PAD, recovery requires the nuclear factor-kappa B (NF-κB) activation. Previously we showed that individually, both ischemia and high glucose activate the canonical and non-canonical arms of the NF-κB pathway, but prolonged high glucose exposure specifically impairs ischemia-induced activation of the canonical NF-κB pathway through activation of protein kinase C beta (PKCβ). Although a cascade of phosphorylation events propels the NF-κB signaling, little is known about the impact of hyperglycemia on the canonical and non-canonical NF-κB pathway signaling. Moreover, signal upstream of PKCβ that lead to its activation in endothelial cells during hyperglycemia exposure have not been well defined. In this study, we used endothelial cells exposed to hyperglycemia and ischemia (HGI) and an array of approximately 250 antibodies to approximately 100 proteins and their phosphorylated forms to identify the NF-κB signaling pathway that is altered in ischemic EC that has been exposed to high glucose condition. Comparison of signals from hyperglycemic and ischemic cell lysates yielded a number of proteins whose phosphorylation was either increased or decreased under HGI conditions. Pathway analyses using bioinformatics tools implicated BLNK/BTK known for B cell antigen receptor (BCR)-coupled signaling. Inhibition of BLNK/BTK in endothelial cells by a specific pharmacological inhibitor terreic acid attenuated PKC activation and restored the IκBα degradation suggesting that these molecules play a critical role in hyperglycemic attenuation of the canonical NF-κB pathway. Thus, we have identified a potentially new component of the NF-κB pathway upstream of PKC in endothelial cells that contributes to the poor post ischemic adaptation during hyperglycemia.

Diabetes mellitus in peripheral artery disease: Beyond a risk factor

Peripheral artery disease (PAD) is one of the major cardiovascular diseases that afflicts a large population worldwide. PAD results from occlusion of the peripheral arteries of the lower extremities. Although diabetes is a major risk factor for developing PAD, coexistence of PAD and diabetes poses significantly greater risk of developing critical limb threatening ischemia (CLTI) with poor prognosis for limb amputation and high mortality. Despite the prevalence of PAD, there are no effective therapeutic interventions as the molecular mechanism of how diabetes worsens PAD is not understood. With increasing cases of diabetes worldwide, the risk of complications in PAD have greatly increased. PAD and diabetes affect a complex web of multiple cellular, biochemical and molecular pathways. Therefore, it is important to understand the molecular components that can be targeted for therapeutic purposes. In this review, we describe some major developments in enhancing the understanding of the interactions of PAD and diabetes. We also provide results from our laboratory in this context.

Alterations of housekeeping proteins in human aged and diseased hearts

Pathological remodeling includes alterations of ion channel function and calcium homeostasis and ultimately cardiac maladaptive function during the process of disease development. Biochemical assays are important approaches for assessing protein abundance and post-translational modification of ion channels. Several housekeeping proteins are commonly used as internal controls to minimize loading variabilities in immunoblotting protein assays. Yet, emerging evidence suggests that some housekeeping proteins may be abnormally altered under certain pathological conditions. However, alterations of housekeeping proteins in aged and diseased human hearts remain unclear. In the current study, immunoblotting was applied to measure three commonly used housekeeping proteins (β-actin, calsequestrin, and GAPDH) in well-procured human right atria (RA) and left ventricles (LV) from diabetic, heart failure, and aged human organ donors. Linear regression analysis suggested that the amounts of linearly loaded total proteins and quantified intensity of total proteins from either Ponceau S (PS) blot-stained or Coomassie Blue (CB) gel-stained images were highly correlated. Thus, all immunoblotting data were normalized with quantitative CB or PS data to calibrate potential loading variabilities. In the human heart, β-actin was reduced in diabetic RA and LV, while GAPDH was altered in aged and diabetic RA but not LV. Calsequestrin, an important Ca2+ regulatory protein, was significantly changed in aged, diabetic, and ischemic failing hearts. Intriguingly, expression levels of all three proteins were unchanged in non-ischemic failing human LV. Overall, alterations of human housekeeping proteins are heart chamber specific and disease context dependent. The choice of immunoblotting loading controls should be carefully evaluated. Usage of CB or PS total protein analysis could be a viable alternative approach for some complicated pathological specimens.

Individuals with Peripheral Artery Disease (PAD) and Type 1 Diabetes Are More Likely to Undergo Limb Amputation than Those with PAD and Type 2 Diabetes

Background: Limited data exist comparing how type 1 diabetes mellitus (DM) and type 2 DM may have differential effects on peripheral artery disease (PAD) severity. We aimed to study the association of type of DM with the procedure utilized in hospitalizations with a diagnosis of PAD. Methods: We used the national inpatient sample databases from 2003 to 2014 to identify hospitalizations with a diagnosis of PAD and type 1 or type 2 DM. Logistic regression was utilized to evaluate the association between type of DM and procedure utilized (amputation-overall, major, endovascular revascularization, surgical revascularization). Results: We identified 14,012,860 hospitalizations with PAD diagnosis and DM, 5.6% (n = 784,720) had type 1 DM. The patients with type 1 DM were more likely to present with chronic limb-threatening ischemia (CLTI) (45.2% vs. 32.0%), ulcer (25.9% vs. 17.7%), or complicated ulcer (16.6% vs. 10.5%) (all p < 0.001) when compared to those with type 2 DM. Type 1 DM was independently and significantly associated with more amputation procedures (adjusted odds ratio = 1.12, 95% confidence interval [CI] I 1.08 to 1.16, p < 0.001). Overall, in-hospital mortality did not differ between the individuals with type 1 and type 2 DM. The overall mean (95% CI) length of stay (in days) was 6.6 (6.5 to 6.6) and was significantly higher for type 1 DM (7.8 [7.7 to 8.0]) when compared to those with type 2 DM (6.5 [6.4 to 6.6]). Conclusion: We observed that individuals with PAD and type 1 DM were more likely to present with CLTI and ulcer and undergo amputation when compared to those with PAD and type 2 diabetes. Further studies are needed to better understand the underlying mechanisms behind these findings and to identify novel interventions to reduce the risk of amputation in patients with type 1 DM.

Gene surgery: Potential applications for human diseases

Gene therapy became in last decade a new emerging therapeutic era showing promising results against different diseases such as cancer, cardiovascular diseases, diabetes, and neurological disorders. Recently, the genome editing technique for eukaryotic cells called CRISPR-Cas (Clustered Regulatory Interspaced Short Palindromic Repeats) has enriched the field of gene surgery with enhanced applications. In the present review, we summarized the different applications of gene surgery for treating human diseases such as cancer, diabetes, nervous, and cardiovascular diseases, besides the molecular mechanisms involved in these important effects. Several studies support the important therapeutic applications of gene surgery in a large number of health disorders and diseases including β-thalassemia, cancer, immunodeficiencies, diabetes, and neurological disorders. In diabetes, gene surgery was shown to be effective in type 1 diabetes by triggering different signaling pathways. Furthermore, gene surgery, especially that using CRISPR-Cas possessed important application on diagnosis, screening and treatment of several cancers such as lung, liver, pancreatic and colorectal cancer. Nevertheless, gene surgery still presents some limitations such as the design difficulties and costs regarding ZFNs (Zinc Finger Nucleases) and TALENs (Transcription Activator-Like Effector Nucleases) use, off-target effects, low transfection efficiency, in vivo delivery-safety and ethical issues.

In experimental peripheral arterial disease, type 2 diabetes alters post-ischemic gene expression

Peripheral arterial disease is characterized by impaired blood flow to tissues outside the heart due to atherosclerosis and it most frequently occurs in the lower extremities. Type 2 diabetes (T2D) is a well-known risk factor that accelerate the course and contributes to poor clinical outcomes of PAD. While there is some evidence that T2D is associated with altered expression of genes involved in regulating PAD severity, our knowledge about the specific genes and pathways involved remains incomplete. We induced experimental PAD or hind limb ischemia in T2D and non-diabetic mice and subjected the ischemic gastrocnemius muscle tissues to genome-wide mRNA transcriptome analysis. We subsequently performed pathway analysis on the top 500 genes that showed the most significant expression differences between the ischemic diabetic and ischemic non-diabetic muscle tissues. Pathway analysis of the differentially expressed genes identified pathways involved in essential biological processes such as "metabolic pathways," "phagosomes," "lysosomes," and "regulation of actin cytoskeleton". Overall, our data provides the opportunity to test hypotheses on the potential role of the altered genes/molecular pathways in poor PAD outcomes in diabetes.