Can dipeptidyl peptidase-4 inhibitors treat cognitive disorders?

The linkage of neurodegenerative diseases with insulin resistance (IR) and type 2 diabetes mellitus (T2DM), including oxidative stress, mitochondrial dysfunction, excessive inflammatory responses and abnormal protein processing, and the correlation between cerebrovascular diseases and hyperglycemia has opened a new window for novel therapeutics for these cognitive disorders. Various antidiabetic agents have been studied for their potential treatment of cognitive disorders, among which the dipeptidyl peptidase-4 (DPP-4) inhibitors have been investigated more recently. So far, DPP-4 inhibitors have demonstrated neuroprotection and cognitive improvements in animal models, and cognitive benefits in diabetic patients with or without cognitive impairments. This review aims to summarize the potential mechanisms, advantages and limitations, and currently available evidence for developing DPP-4 inhibitors as a treatment of cognitive disorders.

Fluorescence enhanced lab-on-a-chip patterned using a hybrid technique of femtosecond laser direct writing and anodized aluminum oxide porous nanostructuring.

In this paper, we demonstrate a simple yet effective hybrid method to fabricate lab-on-a-chip devices on aluminum (Al) foil. Instead of using conventional photoresists and lithography methods, an array of square units is first produced by femtosecond laser direct writing, followed by generating highly ordered anodized aluminum oxide (AAO) nanoporous structures within each unit. The AAO treated area becomes hydrophilic. Next, we functionalize the surrounding area outside the square units to superhydrophobic by electrochemical deposition and further chemical modification. This hydrophilic and hydrophobic pattern allows us to confine the liquid samples to be detected within the hydrophilic AAO detection area. We use rhodamine 6G (R6G) as a probe, and obtain a fluorescence intensity enhancement from R6G by 70 times over a flat surface. This leads to the detection sensitivity of R6G molecules to a concentration as low as 10-17 mol L-1. By mixing R6G with RhB molecules, the fluorescence emission bands shift significantly due to the addition of RhB molecules, showing a significantly improved spectral resolution compared to traditional fluorescence spectrometers for liquid samples. This phenomenon can be attributed to the energy transfer between R6G and RhB under laser excitation, which was enhanced by the AAO nanostructures. The array-based LOC device demonstrated in this paper is simple and convenient to fabricate, has low sample consumption and dramatically enhances the fluorescence yield with improved spectral resolution.

Effects of Type 2 Diabetic Serum on Proliferation and Osteogenic Differentiation of Mesenchymal Stem Cells.

Diabetic patients have an increased risk of osteoporosis-associated fractures. However, the results of most studies of the effects of diabetes on bone mass in patients with type 2 diabetes (T2DM) have been contradictory. To clarify these conflicting findings, we investigated the effects of diabetic serum on the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs). We used human sera from subjects with different levels of glycemic control to culture the MSCs and induce osteogenic differentiation. The rate of MSC proliferation differed when MSCs were cultured with sera from diabetic subjects with different levels of hyperglycemia. Hyperglycemic sera promoted MSC proliferation to some extent, but all the diabetic sera inhibited the differentiation of MSCs to osteoblasts. The effects of type 2 diabetic sera on the proliferation and osteogenic differentiation of MSCs are closely related to glycemic control. Our data demonstrate the importance of stratifying the study population according to glycemic control in clinical research into diabetic osteoporosis.

Egr2 enhances insulin resistance via JAK2/STAT3/SOCS-1 pathway in HepG2 cells treated with palmitate.

Insulin resistance is generally responsible for the pathogenesis of type 2 diabetes mellitus (T2DM). Early growth response proteins-2 (Egr2) has been reported to be able to increase the expression of the suppressors of cytokine signaling-1 (SOCS-1), and impair insulin signaling pathway through suppression of insulin receptor substrates (IRS), including IRS-1 and IRS-2. However, whether Egr2 is directly involved in the development of insulin resistance, and how its potential contributions to insulin resistance still remain unknown. Here, our present investigation found that the expression levels of Egr2 were up-regulated when insulin resistance occurs, and knockdown of Egr2 abolished the effect of insulin resistance in HepG2 cells induced with palmitate (PA). Importantly, inhibition of Egr2 decreased the expression of SOCS-1 as well as reduced phosphorylation of JAK2 and STAT3. And, our data indicated that silencing of Egr2 accelerated hepatic glucose uptake and reversed the impaired lipid metabolism upon insulin resistance. In summary, the present study confirms that Egr2 could deteriorate insulin resistance via the pathway of JAK2/STAT3/SOCS-1 and may shed light on resolving insulin resistance and further the pathogenesis of T2DM.

Comparison of exenatide and acarbose on intra-abdominal fat content in patients with obesity and type-2 diabetes: A randomized controlled trial.

OBJECTIVE: To investigate exenatide, a GLP-1 analogue, compared with acarbose, for intra-abdominal fat reduction in patients with obesity and type-2 diabetes. METHODS: This randomized controlled trial included 36 patients with obesity and type-2 diabetes, who were metformin-unresponsive, receiving metformin/exenatide (GLP-1 group) or metformin/acarbose (control group) for 3 months. Primary end-point: intra-abdominal fat content from baseline to 3 months; Secondary end-points: changes in fasting blood glucose, glycated haemoglobin (HbAlc), fasting insulin, blood lipids, weight, body mass index, and inflammatory cytokines from baseline to 3 months. RESULTS: Intra-abdominal fat content decreased in the GLP-1 group from baseline to 3 months (17,947±5804; 13,717±3628mm2, P=0.001, respectively), but was not significantly reduced in the control group (P=0.197) and at 3 months post-treatment, it was significantly lower in the GLP-1 group than control group (P=0.043). Glucose control, measured by HbA1c (GLP-1: 9.72±1.38; 7.09±0.60%, P<0.001, 9.46±1.25; 7.42±0.84%, P<0.001, respectively) and insulin resistance index LN(HOMA-IR) (GLP-1: 1.58±0.40; 1.01±0.33, P<0.001, Control: 1.53±0.57; 1.10±0.33, P=0.003, respectively) significantly improved in both groups with no significant difference between them. TNF-α, IL-6, and leptin were lower and adiponectin levels higher in the GLP-1 group at 3 months compared with baseline (all P<0.05), but not significantly changed in the control group. TNF-α, IL-6 and leptin levels were similar between groups. Adiponectin level was higher in the GLP-1 group than the control group at 3 months (P=0.025). CONCLUSION: Combined exenatide/metformin reduced intra-abdominal fat content, and enhanced insulin resistance and inflammatory status in patients with obesity and type-2 diabetes, representing a novel treatment regimen.

Discovery and validation of potential bacterial biomarkers for lung cancer.

Microbes are residents in a number of body sites, including the oral and nasal cavities, which are connected to the lung via the pharynx. The associations between oral diseases and increased risk of lung cancer have been reported in previous prospective studies. In this study, we measured variations of salivary microbiota and evaluated their potential association with lung cancer, including squamous cell carcinoma (SCC) and adenocarcinoma (AC). A three-phase study was performed: First, we investigated the salivary microbiota from 20 lung cancer patients (10 SCC and 10 AC) and control subjects (n=10) using a deep sequencing analysis. Salivary Capnocytophaga, Selenomonas, Veillonella and Neisseria were found to be significantly altered in patients with SCC and AC when compared to that in control subjects. Second, we confirmed the significant changes of Capnocytophaga, Veillonella and Neisseria in the same lung cancer patients using quantitative PCR (qPCR). Finally, these bacterial species were further validated on new patient/control cohorts (n=56) with qPCR. The combination of two bacterial biomarkers, Capnocytophaga and Veillonella, yielded a receiver operating characteristic (ROC) value of 0.86 with an 84.6% sensitivity and 86.7% specificity in distinguishing patients with SCC from control subjects and a ROC value of 0.80 with a 78.6% sensitivity and 80.0% specificity in distinguishing patients with AC from control subjects. In conclusion, we have for the first time demonstrated the association of saliva microbiota with lung cancer. Particularly, the combination of the 16S sequencing discovery with qPCR validation studies revealed that the levels of Capnocytophaga and Veillonella were significantly higher in the saliva from lung cancer patients, which may serve as potential biomarkers for the disease detection/classification.

Application of the back-error propagation artificial neural network (BPANN) on genetic variants in the PPAR-γ and RXR-α gene and risk of metabolic syndrome in a Chinese Han population.

This study was aimed to explore the associations between the combined effects of several polymorphisms in the PPAR-γ and RXR-α gene and environmental factors with the risk of metabolic syndrome by back-error propagation artificial neural network (BPANN). We established the model based on data gathered from metabolic syndrome patients (n = 1012) and normal controls (n = 1069) by BPANN. Mean impact value (MIV) for each input variable was calculated and the sequence of factors was sorted according to their absolute MIVs. Generalized multifactor dimensionality reduction (GMDR) confirmed a joint effect of PPAR-γ and RXR-α based on the results from BPANN. By BPANN analysis, the sequences according to the importance of metabolic syndrome risk factors were in the order of body mass index (BMI), serum adiponectin, rs4240711, gender, rs4842194, family history of type 2 diabetes, rs2920502, physical activity, alcohol drinking, rs3856806, family history of hypertension, rs1045570, rs6537944, age, rs17817276, family history of hyperlipidemia, smoking, rs1801282 and rs3132291. However, no polymorphism was statistically significant in multiple logistic regression analysis. After controlling for environmental factors, A1, A2, B1 and B2 (rs4240711, rs4842194, rs2920502 and rs3856806) models were the best models (cross-validation consistency 10/10, P = 0.0107) with the GMDR method. In conclusion, the interaction of the PPAR-γ and RXR-α gene could play a role in susceptibility to metabolic syndrome. A more realistic model is obtained by using BPANN to screen out determinants of diseases of multiple etiologies like metabolic syndrome.

Fatty acid epoxyisoprostane E2 stimulates an oxidative stress response in endothelial cells.

Atherosclerosis is the main underlying cause of major cardiovascular diseases such as stroke and heart attack. Oxidized phospholipids such as oxidized 1-palmitoyl-2-arachidonoyl-sn-Glycero-3-phosphorylcholine (OxPAPC) accumulate in lesions of and promote atherosclerosis. OxPAPC activates endothelial cells, a critical early event of atherogenesis. Epoxyisoprostane E2 (EI) is an oxidized fatty acid contained at the sn-2 position of 1-palmitoyl-2-epoxyisoprostane E2-sn-glycero-3-phosphorylcholine (PEIPC), the most active component of OxPAPC in regulating inflammation. OxPAPC and its components including PEIPC activate endothelial cells to express an array of genes in different categories including oxidative stress response genes such as tumor suppressor gene OKL38 and Heme oxygenase-1 (HO-1). EI can be released by lipase from PEIPC. In this study, we examined the ability of EI to stimulate oxidative stress response in endothelial cells. EI released from OxPAPC and synthetic EI stimulated the expression of oxidative stress response gene OKL38 and antioxidant gene HO-1. Treatment of endothelial cells with EI increased the production of superoxide. NADPH oxidase inhibitor Apocynin and superoxide scavenger N-acetyl-cysteine (NAC) significantly attenuated EI-stimulated expression of OKL38 and HO-1. We further demonstrated that EI activated oxidative stress-sensitive transcription factor Nrf2. Silencing of Nrf2 with siRNA significantly reduced EI stimulated expression of OKL38 and HO-1. Thus, we demonstrated that EI induced oxidative stress in endothelial cells leading to increased expression of oxidative stress response gene OKL38 and HO-1 via Nrf2 signaling pathway relevant to atherosclerosis.

Involvement of non-structural proteins (NS) in influenza A infection and viral tropism.

Hemagglutinin (HA) of influenza A has been reported as the key protein in viral infection. Therefore, the density and the dynamic pattern of this protein in viral envelope will affect the virus to infect target cells. We used a lentiviral system to study the influenza A H1N1 viral infection. Herein we demonstrate that the influenza non-structural proteins (NS) significantly promote viral infection. By substituting NS gene segment from an H1N1 genome set of A/WSN/1933 with the NS segment isolated from another H1N1 substrain genome set, China246, we found that viral infection tropism was significantly altered. The reassortant H1N1 shows almost identical infectivity compared with its parental virus, A/WSN/1933, for the human epithelial cell line HOT, but shows only 1/100 infectivity of its parental virus when infecting the Madin-Darby canine kidney (MDCK) cell line. These results suggest that not only is NS important in the infectivity of human influenza virus, but that it may play a critical role in viral tropism, allowing the virus to mutate and spread to other species.

Association between PPAR-γ and RXR-α gene polymorphism and metabolic syndrome risk: a case-control study of a Chinese Han population.

BACKGROUND AND AIMS: Polymorphisms in peroxisome proliferator activated receptor-γ (PPAR-γ) and retinoid X receptor-α (RXR-α) gene may alter metabolic syndrome (MetS) risks by increasing or decreasing the human adiponectin promoter activity in cells. To test this statement, three potentially functional SNPs of PPAR-γ and four SNPs of RXR-α with minor allele frequency (MAF) ≥0.05 in the Chinese Han population were identified from NCBI dbSNPs database to evaluate their associations with MetS. METHODS: TaqMan assay was performed to test the genotypes in MetS patients (n = 901) and normal controls (n = 1009). Serum adiponectin concentration was measured by ELISA kit. RESULTS: The variant genotypes rs2920502CG and CG/CC, rs4240711GG and AG/GG, rs4842194CC and CT/CC, rs3132291CT, CC and CT/CC were associated with MetS. Furthermore, in the haplotype of PPAR-γ gene, compared with the most common haplotype GC, haplotype CC was associated with an increased risk of MetS (crude p = 0.017). In the haplotype of RXR-α gene, haplotype GCGC was associated with a significant protective effect for MetS [adjusted p = 0.002, OR (95% CI) = 0.718 (0.585-0.882)] compared with the most common haplotype GTAT. After taking smoking, alcohol consumption and physical activity as environmental adjustment factors into the analysis, the result showed A1 A2 A4 A5 A6 A7 B1 (rs3856806, rs2920502, rs180128, rs1045570, rs3132291, rs4240711, rs4842194) was the best model (cross-validation consistency 10/10, p = 0.0107). CONCLUSIONS: The present study suggested that the variant genotypes in PPAR-γ gene could increase the risk of MetS; however, genotypes in RXR-α gene could decrease the risk of MetS in a Chinese Han population.

Application of back propagation artificial neural network on genetic variants in adiponectin ADIPOQ, peroxisome proliferator-activated receptor-γ, and retinoid X receptor-α genes and type 2 diabetes risk in a Chinese Han population.

AIMS: Our study was designed to explore the applied characteristics of the back propagation artificial neural network (BPANN) on studying the genetic variants in adipnectin ADIPOQ, peroxisome proliferator-activated receptor (PPAR)-γ, and retinoid X receptor-α (RXR-α) genes and type 2 diabetes mellitus (T2DM) risks in a Chinese Han population. SUBJECTS AND METHODS: We used BPANN as the fitting model based on data gathered from T2DM patients (n=913) and normal controls (n=1,001). The mean impact value (MIV) for each input variables were calculated, and the sequence of the factors according to their absolute MIVs was sorted. RESULTS: The results from BPANN were compared with multiple logistic regression analysis, and the generalized multifactor dimensionality reduction (GMDR) method was used to calculate the joint effects of ADIPOQ, PPAR-γ, and RXR-α genes. By BPANN analysis, the sequence according to the importance of the T2DM risk factors was in the order of serum adiponectin level, rs3856806, rs7649121, hypertension, rs3821799, rs17827276, rs12495941, rs4240711, age, rs16861194, waist circumference, rs2241767, rs2920502, rs1063539, alcohol drinking, smoking, hyperlipoproteinemia, gender, rs3132291, T2DM family history, rs4842194, rs822394, rs1801282, rs1045570, rs16861205, rs6537944, body mass index, rs266729, and rs1801282. However, compared with multiple logistic regression analysis, only 11 factors were statistically significant. After overweight and obesity were taken as environment adjustment factors into the analysis, model A2 B4 C5 C6 C8 (rs3856806, rs4240711, rs7649121, rs3821799, rs12495941) was the best model (coefficient of variation consistency=10/10, P=0.0107) in the GMDR method. CONCLUSIONS: These results suggested the interactions of ADIPOQ, PPAR-γ, and RXR-α genes might play a role in susceptibility to T2DM. BPANN could be used to analyze the risk factors of diseases and provide more complicated relationships between inputs and outputs.

[The disease characteristics and risk factors of type 2 diabetes mellitus in pedigrees].

OBJECTIVE: To explore the characteristics and risk factors of type 2 diabetes mellitus (T2DM) onset in pedigrees. METHODS: A total of 865 subjects were screened and diagnosed by oral glucose tolerance test (OGTT) based on American Diabetes Association (ADA) criteria. Type 1 diabetes mellitus (T1DM), maturity onset diabetes of the young (MODY) and chondriosome diabetes were excluded by clinical features and laboratory test of insulin and autoantibodies including glutamic acid decarboxylase antibody, insular cellular antibody and insulin autoantibody. A total of 182 pedigrees of T2DM were obtained. RESULTS: No gender difference was found in the prevalence of T2DM (42.59% in male and 48.18% in female respectively, P > 0.05), nor was the newly diagnosed rate (9.89% in male and 11.82% in female, P > 0.05). The onset age was (63.3 ± 12.4) years old in the first generation [(64.4 ± 12.5) years in male and (62.3 ± 10.3) years in female], (47.1 ± 8.7) years old in the second generation [(48.2 ± 9.3) years in male and (46.1 ± 8.1) years in female], (29.6 ± 10.2) years old in the third generation [(28.9 ± 9.5) years in male and (30.0 ± 10.4) years in female]. Compared with normal glucose tolerance (NGT) subjects, newly diagnosed T2DM and impaired glucose regulation (IGR) subjects had higher prevalence of hypertension, hyperlipidemia and smoking but less physical activities. Statistical differences were shown in body weight five years before diagnosis, one years before diagnosis and at diagnosis in newly diagnosed T2DM [(68.4 ± 12.4) kg, (69.5 ± 11.0) kg and (69.1 ± 9.6) kg] and IGR [(66.1 ± 10.7) kg, (65.9 ± 10.7) kg and (65.7 ± 10.4) kg], when compared with NGT [(61.0 ± 10.2) kg, (59.5 ± 11.0) kg and (60.1 ± 10.4) kg, all P < 0.05]. The same results were obtained with waist circumference and waist-hip ratio [(4.1 ± 12.5) cm and 0.92 ± 0.36 in newly diagnosed T2DM while (89.1 ± 10.7) cm and 0.90 ± 0.64 in IGR], when compared with NGT [(82.5 ± 10.1) cm and 0.82 ± 0.25], all P < 0.05. CONCLUSIONS: No gender difference was found in the onset characteristics of T2DM. High prevalence of obesity, hypertension, hyperlipidemia and smoking with less physical activities were associated with T2DM.