Glucagon kinetics assessed by mathematical modelling during oral glucose administration in people spanning from normal glucose tolerance to type 2 diabetes

Background/Objectives

Glucagon is important in the maintenance of glucose homeostasis, with also effects on lipids. In this study, we aimed to apply a recently developed model of glucagon kinetics to determine the sensitivity of glucagon variations (especially, glucagon inhibition) to insulin levels ("alpha-cell insulin sensitivity"), during oral glucose administration.

Subjects/Methods

We studied 50 participants (spanning from normal glucose tolerance to type 2 diabetes) undergoing frequently sampled 5-hr oral glucose tolerance test (OGTT). The alpha-cell insulin sensitivity and the glucagon kinetics were assessed by a mathematical model that we developed previously.

Results

The alpha-cell insulin sensitivity parameter (named SGLUCA; "GLUCA": "glucagon") was remarkably variable among participants (CV=221%). SGLUCA was found inversely correlated with the mean glycemic values, as well as with 2-hr glycemia of the OGTT. When stratifying participants into two groups (normal glucose tolerance, NGT, N=28, and impaired glucose regulation/type 2 diabetes, IGR_T2D, N=22), we found that SGLUCA was lower in the latter (1.50 ± 0.50·10-2 vs. 0.26 ± 0.14·10-2 ng·L-1 GLUCA/pmol·L-1 INS, in NGT and IGR_T2D, respectively, p=0.009; "INS": "insulin").

Conclusions

The alpha-cell insulin sensitivity is highly variable among subjects, and it is different in groups at different glucose tolerance. This may be relevant for defining personalized treatment schemes, in terms of dietary prescriptions but also for treatments with glucagon-related agents.

One-hour post-load glucose levels are associated with hepatic steatosis assessed by transient elastography

AIM

To examine the association between 1-hour plasma glucose (PG) concentration and markers of non-alcoholic fatty liver disease (NAFLD) assessed by transient elastography (TE).

METHODS

We performed TE in 107 metabolically well-characterized non-diabetic White individuals. Controlled attenuation parameter (CAP) was used to quantify liver steatosis, while liver stiffness marker (LS) was used to evaluate fibrosis.

RESULTS

Controlled attenuation parameter correlated significantly with 1-hour PG (r = 0.301, P < 0.01), fasting insulin (r = 0.285, P < 0.01), 2-hour insulin (r = 0.257, P < 0.02), homeostasis model assessment index of insulin resistance (r = 0.252, P < 0.01), high-density lipoprotein cholesterol (r = -0.252, P < 0.02), body mass index (BMI; r = 0.248, P < 0.02) and age (r = 0.212, P < 0.03), after correction for age, sex and BMI. In a multivariable linear regression analysis, 1-hour PG (β = 0.274, P = 0.008) and fasting insulin levels (β = 0.225, P = 0.029) were found to be independent predictors of CAP. After excluding subjects with prediabetes, 1-hour PG was the sole predictor of CAP variation (β = 0.442, P < 0.001). In a logistic regression model, we observed that the group with 1-hour PG ≥  8.6 mmol/L (155 mg/dL) had a significantly higher risk of steatosis (odds ratio 3.98, 95% confidence interval 1.43-11.13; P = 0.008) than individuals with 1-hour PG <  8.6 mmol/L, after correction for potential confounders. No association was observed between 1-hour PG and LS.

CONCLUSION

Our data confirm that 1-hour PG ≥  8.6 mmol/L is associated with higher signs of NAFLD, even among individuals with normal glucose tolerance, categorized as low risk by canonical diagnostic standards. TE is a safe low-impact approach that could be employed for stratifying the risk profile in these patients, with a high level of accuracy.

Higher circulating levels of proneurotensin are associated with increased risk of incident NAFLD

BACKGROUND

Neurotensin (NT), an intestinal peptide able to promote fat absorption, is implicated in the pathogenesis of obesity. Increased levels of proneurotensin (pro-NT), a stable NT precursor fragment, have been found in subjects with nonalcoholic fatty liver disease (NAFLD); however, whether higher pro-NT levels are associated with an increased NAFLD risk independently of other metabolic risk factors is unsettled.

METHODS

Ultrasound-defined presence of NAFLD was assessed on 303 subjects stratified into tertiles according to fasting pro-NT levels. The longitudinal association between pro-NT levels and NAFLD was explored on the study participants without NAFLD at baseline reexamined after 5 years of follow-up (n = 124).

RESULTS

Individuals with higher pro-NT levels exhibited increased adiposity, a worse lipid profile, and insulin sensitivity as compared to the lowest tertile of pro-NT. Prevalence of NAFLD was progressively increased in the intermediate and highest pro-NT tertile as compared to the lowest tertile. In a logistic regression analysis adjusted for several confounders, individuals with higher pro-NT levels displayed a raised risk of having NAFLD (OR = 3.43, 95%CI = 1.48-7.97, p = 0.004) than those in the lowest pro-NT tertile. Within the study cohort without NAFLD at baseline, subjects with newly diagnosed NAFLD at follow-up exhibited higher baseline pro-NT levels than those without incident NAFLD. In a cox hazard regression analysis model adjusted for anthropometric and metabolic parameters collected at baseline and follow-up visit, higher baseline pro-NT levels were associated with an increased risk of incident NAFLD (HR = 1.52, 95%CI = 1.017-2.282, p = 0.04).

CONCLUSION

Higher pro-NT levels are a predictor of NAFLD independent of other metabolic risk factors.

Argas ticks (Ixodida: Argasidae) on migratory birds from Africa: first record of a genotype close to Argas africolumbae in Italy

In spring, migratory birds reach Europe, mainly from sub-Saharan Africa or from northern African countries. Avian species may be implicated in the spread of pathogens, either as reservoirs, hosts or carriers of infected ectoparasites. In 2021, on Ventotene Island (Latium region, Italy) within a project focused on the potential incoming pathogens via migratory birds from Africa, we found two larvae of Argas sp., on the redstart Phoenicurus phoenicurus, that shared morphological features with the African Argas (Argas) africolumbae. Comparison of the tested larval DNA sequences to the adult reference sequences showed the highest identity (> 92%) with homologous sequences of A. africolumbae collected in South Africa and in Spain. This study reports the first detection of Argas africolumbae-like specimens in Italy.

Progress in Dental Adhesive Materials

There have been significant advances in adhesive dentistry in recent decades, with efforts being made to improve the mechanical and bonding properties of resin-based dental adhesive materials. Various attempts have been made to achieve versatility, introducing functional monomers and silanes into the materials' composition to enable the chemical reaction with tooth structure and restorative materials and a multimode use. The novel adhesive materials also tend to be simpler in terms of clinical use, requiring reduced number of steps, making them less technique sensitive. However, these materials must also be reliable and have a long-lasting bond with different substrates. In order to fulfill these arduous tasks, different chemical constituents and different techniques are continuously being developed and introduced into dental adhesive materials. This critical review aims to discuss the concepts behind novel monomers, bioactive molecules, and alternative techniques recently implemented in adhesive dentistry. Incorporating monomers that are more resistant to hydrolytic degradation and functional monomers that enhance the micromechanical retention and improve chemical interactions between adhesive resin materials and various substrates improved the performance of adhesive materials. The current trend is to blend bioactive molecules into adhesive materials to enhance the mechanical properties and prevent endogenous enzymatic degradation of the dental substrate, thus ensuring the longevity of resin-dentin bonds. Moreover, alternative etching materials and techniques have been developed to address the drawbacks of phosphoric acid dentin etching. Altogether, we are witnessing a dynamic era in adhesive dentistry, with advancements aiming to bring us closer to simple and reliable bonding. However, simplification and novelty should not be achieved at the expense of material properties.

Glucagon induces the hepatic expression of inflammatory markers in vitro and in vivo

Glucagon exerts multiple hepatic actions, including stimulation of glycogenolysis/gluconeogenesis. The liver plays a crucial role in chronic inflammation by synthesizing proinflammatory molecules, which are thought to contribute to insulin resistance and hyperglycaemia. Whether glucagon affects hepatic expression of proinflammatory cytokines and acute-phase reactants is unknown. Herein, we report a positive relationship between fasting glucagon levels and circulating interleukin (IL)-1β (r = 0.252, p = .042), IL-6 (r = 0.230, p = .026), fibrinogen (r = 0.193, p = .031), complement component 3 (r = 0.227, p = .024) and high sensitivity C-reactive protein (r = 0.230, p = .012) in individuals without diabetes. In CD1 mice, 4-week continuous treatment with glucagon induced a significant increase in circulating IL-1β (p = .02), and IL-6 (p = .001), which was countered by the contingent administration of the glucagon receptor antagonist, GRA-II. Consistent with these results, we detected a significant increase in the hepatic activation of inflammatory pathways, such as expression of NLRP3 (p < .02), and the phosphorylation of nuclear factor kappaB (NF-κB; p < .02) and STAT3 (p < .01). In HepG2 cells, we found that glucagon dose-dependently stimulated the expression of IL-1β (p < .002), IL-6 (p < .002), fibrinogen (p < .01), complement component 3 (p < .01) and C-reactive protein (p < .01), stimulated the activation of NLRP3 inflammasome (p < .01) and caspase-1 (p < .05), induced the phosphorylation of TRAF2 (p < .01), NF-κB (p < .01) and STAT3 (p < .01). Preincubating cells with GRA-II inhibited the ability of glucagon to induce an inflammatory response. Using HepaRG cells, we confirmed the dose-dependent ability of glucagon to stimulate the expression of NLRP3, the phosphorylation of NF-κB and STAT3, in the absence of GRA-II. These results suggest that glucagon has proinflammatory effects that may participate in the pathogenesis of hyperglycaemia and unfavourable cardiometabolic risk profile.

The Triglycerides and Glucose (TyG) Index Is Associated with 1-Hour Glucose Levels during an OGTT

BACKGROUND AND OBJECTIVES

Among individuals with normal glucose tolerance (NGT), subjects with high levels of plasma glucose (≥155 mg/dL) at sixty minutes during an oral glucose tolerance test (1h-OGTT) are at an increased risk of developing type 2 diabetes. We investigated the association between the triglycerides and glucose (TyG) index, a novel marker of insulin resistance, with 1h-OGTT glucose plasma concentrations.

MATERIAL AND METHODS

1474 non-diabetic Caucasian subjects underwent a 75 g OGTT and were divided into two groups according to the cutoff 1h-OGTT plasma glucose < 155 mg/dL (NGT-1h-low) and ≥ 155 mg/dL (NGT-1h-high). The TyG index was calculated as ln [fasting triglycerides (milligrams per deciliter) × fasting blood glucose (milligrams per deciliter)/2]. Multivariable linear and logistic regression analyses were used to establish the contribution of the TyG index to the variability of 1h-OGTT glucose, and how the former affected the risk of being NGT-1h-high.

RESULTS

1004 individuals were NGT-1h-low and 470 were NGT-1h-high. The TyG index was higher for NGT-1h-high (p = 0.001) individuals, and it was an independent factor influencing 1h-OGTT glycemia (β = 0.191, p < 0.001) after correcting for age, sex, and BMI. The TyG index was the strongest marker associated with the risk of being NGT-1h-high (OR = 1.703, CI 95% 1.34-2.17, p < 0.001) when compared with FPG (OR = 1.054, CI 95% 1.04-1.07, p < 0.001) and the HOMA-IR (OR = 1.156, CI 95% 1.08-1.23, p < 0.001).

CONCLUSIONS

Our study demonstrated that the TyG index, an efficient and cost-effective marker of insulin resistance, is associated with the variability of early post-challenge glucose levels and is an independent marker of being NGT-1h-high.

Chemical Compounds and Ambient Factors Affecting Pancreatic Alpha-Cells Mass and Function: What Evidence?

The exposure to different substances present in the environment can affect the ability of the human body to maintain glucose homeostasis. Some review studies summarized the current evidence about the relationships between environment and insulin resistance or beta-cell dysfunction. Instead, no reviews focused on the relationships between the environment and the alpha cell, although in recent years clear indications have emerged for the pivotal role of the alpha cell in glucose regulation. Thus, the aim of this review was to analyze the studies about the effects of chemical, biological, and physical environmental factors on the alpha cell. Notably, we found studies focusing on the effects of different categories of compounds, including air pollutants, compounds of known toxicity present in common objects, pharmacological agents, and compounds possibly present in food, plus studies on the effects of physical factors (mainly heat exposure). However, the overall number of relevant studies was limited, especially when compared to studies related to the environment and insulin sensitivity or beta-cell function. In our opinion, this was likely due to the underestimation of the alpha-cell role in glucose homeostasis, but since such a role has recently emerged with increasing strength, we expect several new studies about the environment and alpha-cell in the near future.

The Functional Polymorphism of DDAH2 rs9267551 Is an Independent Determinant of Arterial Stiffness

Background: The association of circulating asymmetric dimethylarginine (ADMA) levels with cardiovascular risk and arterial stiffness has been reportedly demonstrated, although the causal involvement of ADMA in the pathogenesis of these conditions is still debated. Dimethylaminohydrolase 2 (DDAH2) is the enzyme responsible for ADMA hydrolysis in the vasculature, and carriers of the polymorphism rs9267551 C in the 5′-UTR of DDAH2 have been reported to have higher DDAH2 expression and reduced levels of serum ADMA.

Approach and Results: We genotyped rs9267551 in 633 adults of European ancestry and measured their carotid–femoral pulse wave velocity (cfPWV), the gold-standard method to estimate arterial stiffness. cfPWV resulted significantly lower in rs9267551 C allele carriers (Δ = −1.12 m/s, P < 0.01) after correction for age, sex and BMI, and a univariate regression showed that the presence of rs9267551 C variant was negatively associated with cfPWV (β = −0.110, P < 0.01). In a multivariable regression model, subjects carrying the rs9267551 C allele manifested significantly lower cfPWV than GG carriers (β = −0.098, P = 0.01) independently from several potential confounders. We measured circulating ADMA levels in a subset of 344 subjects. A mediation analysis revealed that the effect of DDAH2 rs9267551 genotype on cfPWV was mediated by the variation in ADMA levels.

Conclusions: These evidences hint that the presence of rs9267551 C allele may explain, at least in part, a reduction in vessel rigidity as measured by cfPWV, and support the attribution of a causative role to ADMA in the pathogenesis of arterial stiffness.

Vitamin D Serum Levels in Subjects Tested for SARS-CoV-2: What Are the Differences among Acute, Healed, and Negative COVID-19 Patients? A Multicenter Real-Practice Study

Vitamin D might play a role in counteracting COVID-19, albeit strong evidence is still lacking in the literature. The present multicenter real-practice study aimed to evaluate the differences of 25(OH)D₃ serum levels in adults tested for SARS-CoV-2 (acute COVID-19 patients, subjects healed from COVID-19, and non-infected ones) recruited over a 6-month period (March-September 2021). In a sample of 117 subjects, a statistically significant difference was found, with acute COVID-19 patients demonstrating the lowest levels of serum 25(OH)D₃ (9.63 ± 8.70 ng/mL), significantly lower than values reported by no-COVID-19 patients (15.96 ± 5.99 ng/mL, p = 0.0091) and healed COVID-19 patients (11.52 ± 4.90 ng/mL, p > 0.05). Male gender across the three groups displayed unfluctuating 25(OH)D₃ levels, hinting at an inability to ensure adequate levels of the active vitamin D3 form (1α,25(OH)2D3). As a secondary endpoint, we assessed the correlation between serum 25(OH)D₃ levels and pro-inflammatory cytokine interleukin-6 (IL-6) in patients with extremely low serum 25(OH)D₃ levels (<1 ng/mL) and in a subset supplemented with 1α,25(OH)₂D₃. Although patients with severe hypovitaminosis-D showed no significant increase in IL-6 levels, acute COVID-19 patients manifested high circulating IL-6 at admission (females = 127.64 ± 22.24 pg/mL, males = 139.28 ± 48.95 ng/mL) which dropped drastically after the administration of 1α,25(OH)₂D₃ (1.84 ± 0.77 pg/mL and 2.65 ± 0.92 ng/mL, respectively). Taken together, these findings suggest that an administration of 1α,25(OH)₂D₃ might be helpful for treating male patients with an acute COVID-19 infection. Further studies on rapid correction of vitamin D deficiency with fast acting metabolites are warranted in COVID-19 patients.

The TRIB3 R84 variant is associated with increased left ventricular mass in a sample of 2426 White individuals

Background

Prior studies in animal models showed that increased cardiac expression of TRIB3 has a pathogenic role in inducing left ventricular mass (LVM). Whether alterations in TRIB3 expression or function have a pathogenic role in inducing LVM increase also in humans is still unsettled. In order to address this issue, we took advantage of a nonsynonymous TRIB3 Q84R polymorphism (rs2295490), a gain-of-function amino acid substitution impairing insulin signalling, and action in primary human endothelial cells which has been associated with insulin resistance, and early vascular atherosclerosis.

Methods

SNP rs2295490 was genotyped in 2426 White adults in whom LVM index (LVMI) was assessed by validated echocardiography-derived measures.

Results

After adjusting for age and sex, LVMI progressively and significantly increased from 108 to 113, to 125 g/m² in Q84Q, Q84R, and R84R individuals, respectively (Q84R vs. Q84Q, P = 0.03; R84R vs. Q84Q, P < 0.0001). The association between LVMI and the Q84R and R84R genotype remained significant after adjusting for blood pressure, smoking habit, fasting glucose levels, glucose tolerance status, anti-hypertensive treatments, and lipid-lowering therapy (Q84R vs. Q84Q, P = 0.01; R84R vs. Q84Q, P < 0.0001).

Conclusions

We found that the gain-of-function TRIB3 Q84R variant is significantly associated with left ventricular mass in a large sample of White nondiabetic individual of European ancestry.

Personalizing ocrelizumab treatment in Multiple Sclerosis: What can we learn from Sars-Cov2 pandemic?

During SARS-CoV-2 pandemic, we adopted a personalized delayed protocol for ocrelizumab infusions in Relapsing Remitting Multiple Sclerosis (RRMS) patients according to the national recommendations. Out of the 83 RRMS patients whose infusion was scheduled between March and December 2020, 56 patients experienced a delay in treatment based on MS severity and SARS-CoV2 infection risk profile. In most cases, the immunophenotype was performed monthly to guide re-infusions. Specifically, B CD19 + cells repopulation rate was monitored. Mean infusion delay was 103,1 [SD 40,6] days, and none of the patients presented relapses or active disease at MRI at the end of the observation period. Treatment naïve status and the interval between immunophenotyping and the last ocrelizumab infusion were predictors of earlier B CD19 + cells repopulation. Two patients contracted SARS-CoV2 with complete recovery. Definitive data about Sars-Cov2 vaccine efficacy in patients treated with ocrelizumab are still lacking. Our findings suggest that a personalized treatment with a delayed infusion schedule does not compromise ocrelizumab short-term efficacy and may help to lengthen the therapeutic window for an effective response to SARS-CoV2 vaccine.

Dentin Cross-linking Effect of Carbodiimide After 5 Years

Carbodiimide (EDC)-based dentin primers preserve hybrid layer (HL) integrity. However, aging >1 y has not been investigated. The present study examined whether the cross-linking effect of EDC was reflected in dentin bond strength, endogenous enzymatic activity, and the chemical profile of the HL after 5-y aging in artificial saliva. Noncarious human third molars (N = 42) were cut to expose middle/deep coronal dentin and treated as follows: group 1, dentin etched with 35% H₃PO₄, pretreated with a 0.3M aqueous EDC primer for 1 min and restored with XP Bond (Dentsply Sirona); group 2, as in group 1 but without EDC pretreatment; group 3, Clearfil SE Bond (Kuraray-Noritake) primer applied to dentin surface, followed by EDC pretreatment as in group 1 and application of bond; group 4, as in group 3 without EDC pretreatment. After composite buildup, the specimens were cut into sticks or slabs, depending on the experiment. All tests were performed at baseline (T0) and after 5 y of aging (T5) in artificial saliva at 37 °C. Microtensile bond strength (µTBS) was tested at a crosshead speed of 1 mm/min until failure. Endogenous enzymatic activity was investigated with in situ zymography. The chemical profile of HL was determined via Raman spectroscopy. Three-way analysis of variance and post hoc Tukey test were used to analyze µTBS and in situ zymography data (α = 0.05). EDC pretreatment and aging significantly influenced µTBS and in situ zymography results (P < 0.05). Higher bond strength and lower gelatinolytic activity were identified in the EDC-treated groups at T5 (P < 0.05), especially in the etch-and-rinse groups. Raman spectra revealed less defined amide III peaks in control specimens at T5. The EDC cross-linking effect persisted in the HL for 5 y in terms of bond strength, collagen structure preservation, and dentinal enzyme silencing.

Tick species from Africa by migratory birds: a 3-year study in Italy

The role of resident or migratory birds in dispersal of tick species and tick-borne pathogens is still poorly known in Italy. We report here the results of a 3-year project based on sampling ticks from migratory birds, as well as from the vegetation at three stop-over sites for migrants, namely the islands of Ventotene (Latium), Asinara (Sardinia) and Ustica (Sicily). During the spring seasons from 2017-2019, in total 2681 ticks were collected, 2344 of which were sampled from migratory birds and 337 from the vegetation. Ticks were identified by morphology or by molecular tools when necessary. In total, 16 tick species were identified among which the following were exclusively found on birds: Hyalomma rufipes (43.3%), Hy. truncatum (0.1%), Ixodes frontalis (11.8%), Ix. inopinatus (0.2%), Ix. ricinus (3%), Haemaphysalis punctata (0.08%), Hae. erinacei (0.1%), Amblyomma variegatum (0.08%) and Argas vulgaris 0.1%), whereas five species were exclusively collected from the vegetation: Rhipicephalus bursa (10.5%), Rh. turanicus (5.9%), Rh. sanguineus sensu lato (2%), Rh. pusillus (2.4%), Hae. sulcata (0.08%). Hy. marginatum (10.3%) and Ix. ventalloi (9.3%) were found both on birds and on the vegetation on the island Ustica. It is worth noting that the search for ticks on the vegetation did not detect allochthonous tick species. Although we found several interesting local species and allochthonous ticks like Hy. rufipes, Am. variegatum and Ar. vulgaris on birds, further investigations are needed to better define the possible role of migratory birds in the introduction of ticks and tick-borne diseases in Italy, above all after the evidence of imported ticks positive to Crimean Congo hemorrhagic fever (CCHF) virus in several European countries.

CD31+ Extracellular Vesicles From Patients With Type 2 Diabetes Shuttle a miRNA Signature Associated With Cardiovascular Complications

Innovative biomarkers are needed to improve the management of patients with type 2 diabetes mellitus (T2DM). Blood circulating miRNAs have been proposed as a potential tool to detect T2DM complications, but the lack of tissue specificity, among other reasons, has hampered their translation to clinical settings. Extracellular vesicle (EV)-shuttled miRNAs have been proposed as an alternative approach. Here, we adapted an immunomagnetic bead-based method to isolate plasma CD31⁺ EVs to harvest vesicles deriving from tissues relevant for T2DM complications. Surface marker characterization showed that CD31⁺ EVs were also positive for a range of markers typical of both platelets and activated endothelial cells. After characterization, we quantified 11 candidate miRNAs associated with vascular performance and shuttled by CD31⁺ EVs in a large (n = 218) cross-sectional cohort of patients categorized as having T2DM without complications, having T2DM with complications, and control subjects. We found that 10 of the tested miRNAs are affected by T2DM, while the signature composed by miR-146a, -320a, -422a, and -451a efficiently identified T2DM patients with complications. Furthermore, another CD31⁺ EV-shuttled miRNA signature, i.e., miR-155, -320a, -342-3p, -376, and -422a, detected T2DM patients with a previous major adverse cardiovascular event. Many of these miRNAs significantly correlate with clinical variables held to play a key role in the development of complications. In addition, we show that CD31⁺ EVs from patients with T2DM are able to promote the expression of selected inflammatory mRNAs, i.e., CCL2, IL-1α, and TNFα, when administered to endothelial cells in vitro. Overall, these data suggest that the miRNA cargo of plasma CD31⁺ EVs is largely affected by T2DM and related complications, encouraging further research to explore the diagnostic potential and the functional role of these alterations.

HDL (High-Density Lipoprotein) and ApoA-1 (Apolipoprotein A-1) Potentially Modulate Pancreatic α-Cell Glucagon Secretion

OBJECTIVE

Subjects with low levels of HDL (high-density lipoprotein) and ApoA-1 (apolipoprotein A-1) have increased risk to develop type 2 diabetes. HDL levels are an independent predictor of β-cell function and positively modulate it. Type 2 diabetes is characterized by defects in both β and α-cell function, but the effect of HDL and ApoA1 on α-cell function is unknown. Approach and Results: We observed a significant negative correlation (r=-0.422, P<0.0001) between HDL levels and fasting glucagon in a cohort of 132 Italian subjects. In a multivariable regression analysis including potential confounders such as age, sex, BMI, triglycerides, total cholesterol, fasting and 2-hour postload glucose, and fasting insulin, the association between HDL and fasting glucagon remained statistically significant (β=-0.318, P=0.006). CD1 mice treated with HDL or ApoA-1 for 3 consecutive days showed a 32% (P<0.001) and 23% (P<0.05) reduction, respectively, in glucagon levels following insulin-induced hypoglycemia, compared with controls. Treatment of pancreatic αTC1 clone 6 cells with HDL or ApoA-1 for 24 hours resulted in a significant reduction of glucagon expression (P<0.04) and secretion (P<0.01) after an hypoglycemic stimulus and increased Akt (RAC-alpha serine/threonine-protein kinase) and FoxO1 (forkhead/winged helix box gene, group O-1) phosphorylation. Pretreatment with Akt inhibitor VIII, PI3K (phosphatidylinositol 3-kinase) inhibitor LY294002, and HDL receptor SCARB-1 (scavenger receptor class B type 1) inhibitor BLT-1 (block lipid transport-1) restored αTC1 cell response to low glucose levels.

CONCLUSIONS

These results support the notion that HDL and ApoA-1 modulate glucagon expression and secretion by binding their cognate receptor SCARB-1, and activating the PI3K/Akt/FoxO1 signaling cascade in an in vitro α-cell model. Overall, these results raise the hypothesis that HDL and ApoA-1 may have a role in modulating glucagon secretion.

Association between Serum Mg2+ Concentrations and Cardiovascular Organ Damage in a Cohort of Adult Subjects

Magnesium (Mg²⁺) levels are associated with insulin resistance, hypertension, atherosclerosis, and type 2 diabetes (T2DM). We evaluated the clinical utility of physiological Mg²⁺ in assessing subclinical cardiovascular organ damage including increased carotid artery intima- media thickness (c-IMT) and left ventricular mass index (LVMI) in a cohort of well-characterized adult non-diabetic individuals. Age- and gender-adjusted correlations between Mg²⁺ and metabolic parameters showed that Mg²⁺ circulating levels were correlated negatively with body mass index (BMI), fasting glucose, and 2h-oral glucose tolerance test (OGTT) glucose. Similarly, Mg²⁺ levels were significantly and negatively related to c-IMT and LVMI. A multivariate regression analysis revealed that age (β = 0.440; p < 0.0001), BMI (β = 0.225; p < 0.0001), and Mg²⁺ concentration (β = −0.122; p < 0.01) were independently associated with c-IMT. Age (β = 0.244; p = 0.012), Mg²⁺ (β = −0.177; p = 0.019), and diastolic blood pressure (β = 0.184; p = 0.038) were significantly associated with LVMI in women, while age (β = 0.211; p = 0.019), Mg²⁺ (β = −0.171; p = 0.038) and the homeostasis model assessment index of insulin resistance (HOMA-IR) (β = −0.211; p = 0.041) were the sole variables associated with LVMI in men. In conclusion, our data support the hypothesis that the assessment of Mg²⁺ as part of the initial work-up might help unravel the presence of subclinical organ damage in subjects at increased risk of cardiovascular complications.

The Phosphatase PHLPP2 Plays a Key Role in the Regulation of Pancreatic Beta-Cell Survival

Currently available antidiabetic treatments fail to halt, and may even exacerbate, pancreatic β-cell exhaustion, a key feature of type 2 diabetes pathogenesis; thus, strategies to prevent, or reverse, β-cell failure should be actively sought. The serine threonine kinase Akt has a key role in the regulation of β-cell homeostasis; among Akt modulators, a central role is played by pleckstrin homology domain leucine-rich repeat protein phosphatase (PHLPP) family. Here, taking advantage of an in vitro model of chronic exposure to high glucose, we demonstrated that PHLPPs, particularly the second family member called PHLPP2, are implicated in the ability of pancreatic β cells to deal with glucose toxicity. We observed that INS-1 rat pancreatic β cell line maintained for 12-15 passages at high (30 mM) glucose concentrations (INS-1 HG) showed increased expression of PHLPP2 and PHLPP1 both at mRNA and protein level as compared to INS-1 maintained for the same number of passages in the presence of normal glucose levels (INS-1 NG). These changes were paralleled by decreased phosphorylation of Akt and by increased expression of apoptotic and autophagic markers. To investigate if PHLPPs had a casual role in the alteration of INS-1 homeostasis observed upon chronic exposure to high glucose concentrations, we took advantage of shRNA technology to specifically knock-down PHLPPs. We obtained proof-of-concept evidence that modulating PHLPPs expression may help to restore a healthy β cell mass, as the reduced expression of PHLPP2/1 was accompanied by a recovered balance between pro- and antiapoptotic factor levels. In conclusion, our data provide initial support for future studies aimed to identify pharmacological PHLPPs modulator to treat beta-cell survival impairment. They also contribute to shed some light on β-cell dysfunction, a complex and unsatisfactorily characterized phenomenon that has a central causative role in the pathogenesis of type 2 diabetes.

Are Circulating Mg2+ Levels Associated with Glucose Tolerance Profiles and Incident Type 2 Diabetes?

Magnesium (Mg²⁺) is an enzyme co-factor that plays a key role in many biochemical reactions, as well as in glucose metabolism. Clinical evidences have demonstrated that depletion of serum Mg²⁺ increases exponentially with the duration of type 2 diabetes mellitus (T2DM). Diabetes is associated with low Mg²⁺, and hypomagnesemia is associated with insulin resistance, inflammation, and increased risk for cardiovascular disease. In subjects at high risk of inflammation and insulin resistance, supplementation of Mg²⁺ alone ameliorates both phenotypes, slowing the development and progression of hepatic steatosis. We analyze the relationship between serum Mg²⁺ levels and the onset of T2DM in a large cohort of well-characterized adult white individuals participating in the CATAMERI study, who were reexamined after a mean follow-up of 5.6 ± 0.9 years. In our analysis we acquired a significant negative correlation between Mg²⁺ levels, fasting glucose, and 2h-post load glucose in subjects who underwent an OGTT. Moreover, Mg²⁺ levels correlated negatively with fasting insulin levels, and positively with the lipid profile. As for the detrimental effect of lower circulating Mg²⁺ levels, our data revealed a significant reduction of T2DM risk of about 20% for each 1 mg/dL increase of circulating Mg²⁺. The present results are consistent with the theory that Mg²⁺ supplementation could ameliorate insulin sensitivity reducing the risk to develop T2DM.

A functional variant of the dimethylarginine dimethylaminohydrolase-2 gene is associated with myocardial infarction in type 2 diabetic patients

Background

Myocardial infarction is the main mortality cause in patients with type 2 diabetes (T2DM). Endothelial dysfunction due to reduced bioavailability of nitric oxide (NO) is an early step of atherogenesis. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of NO synthesis, and it is metabolized by the enzymes dimethylarginine dimethylaminohydrolase (DDAH) 1 and 2. The functional variant rs9267551 C, in the promoter region of DDAH2, has been linked to increased DDAH2 expression, and lower ADMA plasma levels, and was associated with lower risk of coronary artery disease in large-scale genome-wide association studies (GWAS) performed in the general population. However, it is unknown whether this association holds true in T2DM patients. To address this issue, we investigated whether rs9267551 is associated with risk of myocardial infarction in two cohorts of T2DM patients.

Methods

SNP rs9267551 was genotyped in 1839 White T2DM patients from the Catanzaro Study (CZ, n = 1060) and the Gargano Heart Study-cross sectional design (GHS, n = 779). Cases were patients with a previous myocardial infarction, controls were asymptomatic patients with neither previous myocardial ischemia nor signs of it at resting and during a maximal symptom limited stress electrocardiogram.

Results

Carriers of allele rs9267551 C showed a dose dependent reduction in the risk of myocardial infarction [(CZ = OR 0.380, 95% CI 0.175–0.823, p = 0.014), (GHS = 0.497, 0.267–0.923, p = 0.027), (Pooled = 0.458, 0.283–0.739, p = 0.001)] which remained significant after adjusting for sex, age, BMI, smoking, HbA1c, total cholesterol HDL, and triglyceride levels [(CZ = 0.307, 0.106–0.885, p = 0.029), (GHS = 0.512, 0.270–0.970, p = 0.040), (Pooled = 0.458, 0.266–0.787, p = 0.005)].

Conclusions

We found that rs9267551 polymorphism is significantly associated with myocardial infarction in T2DM patients of European ancestry from two independent cohorts. It is possible that in subjects carrying the protective C allele less ADMA accumulates in endothelial cells causing vascular protection as a consequence of higher nitric oxide availability.

The polymorphism rs35767 at IGF1 locus is associated with serum urate levels

Previous studies suggested that the IGF-1/IGF-1 receptor signaling pathway may contribute to regulate uric acid levels. To confirm this hypothesis, we assessed the effects of the IGF-1-raising genetic variant rs35767 on urate levels in serum and urine, and we investigated IGF-1 ability to modulate the expression of transporters involved in reabsorption and secretion of uric acid in the kidney. The study population included 2794 adult Whites. 24-hour urinary uric acid concentration was available for 229 subjects. rs35767 polymorphism was screened using TaqMan genotyping assays. HEK293 (human embryonic kidney-293) cell line was treated with IGF-1 (1, 5, 10, 50 nM) for 24-hours, and differences in the expression of urate transporters were evaluated via Western Blot and real time rtPCR. Individuals carrying the IGF-1-raising allele (rs35767 T) exhibited significantly lower levels of serum urate according to both additive and recessive models, after correction for gender, age, BMI, glucose tolerance, glomerular filtration rate, and anti-hypertensive treatment. TT genotype carriers displayed higher uricosuria than C allele carriers did, after adjusting for confounders. Exposure of HEK293 cells to IGF-1 resulted in a dose-dependent increase of uric acid transporters deputed to uric acid excretion (MRP4, NPT1 and BCRP), and reduction of GLUT9 expression, the major mediator of uric acid reabsorption, both at mRNA and protein level. We observed a significant association between the functional polymorphism rs35767 near IGF1 with serum urate concentrations and we provide a mechanistic explanation supporting a causal role for IGF-1 in the regulation of uric acid homeostasis.

Short-term sustained hyperglycaemia fosters an archetypal senescence-associated secretory phenotype in endothelial cells and macrophages

Diabetic status is characterized by chronic low-grade inflammation and an increased burden of senescent cells. Recently, the senescence-associated secretory phenotype (SASP) has been suggested as a possible source of inflammatory factors in obesity-induced type 2 diabetes. However, while senescence is a known consequence of hyperglycaemia, evidences of SASP as a result of the glycaemic insult are missing. In addition, few data are available regarding which cell types are the main SASP-spreading cells in vivo. Adopting a four-pronged approach we demonstrated that: i) an archetypal SASP response that was at least partly attributable to endothelial cells and macrophages is induced in mouse kidney after in vivo exposure to sustained hyperglycaemia; ii) reproducing a similar condition in vitro in endothelial cells and macrophages, hyperglycaemic stimulus largely phenocopies the SASP acquired during replicative senescence; iii) in endothelial cells, hyperglycaemia-induced senescence and SASP could be prevented by SOD-1 overexpression; and iiii) ex vivo circulating angiogenic cells derived from peripheral blood mononuclear cells from diabetic patients displayed features consistent with the SASP. Overall, the present findings document a direct link between hyperglycaemia and the SASP in endothelial cells and macrophages, making the SASP a highly likely contributor to the fuelling of low-grade inflammation in diabetes.

Teneligliptin enhances the beneficial effects of GLP-1 in endothelial cells exposed to hyperglycemic conditions

High-glucose-induced oxidative stress contributes to cardiovascular endothelial damage in diabetes. Glucagon-like peptide 1 (GLP-1) is beneficial to endothelial cells, but its effects are diminished when cells are continuously exposed to high glucose. Teneligliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor that prevents oxidative stress, apoptosis and the metabolic memory effect. We explored the potential additive effects of Teneligliptin and GLP-1 in hyperglycemia-damaged endothelial cells. Human umbilical vein endothelial cells (HUVECs) were exposed to normal-glucose (5 mmol/L) or high-glucose (HG, 25 mmol/L) for 21 days, or to HG for 14 days followed by normal-glucose for 7 days (HM). These cells were continually treated with Teneligliptin 3.0 μmol/L, alone or in combination with an acute dose of GLP-1 50 nmol/L. DPP-4 was upregulated under hyperglycemic conditions, but Teneligliptin reduced DPP-4 expression and activity. Simultaneous Teneligliptin and GLP-1 synergistically increased the antioxidant response and reduced ROS levels in HG- and HM-exposed HUVECs. Concurrent treatment also enhanced cell proliferation, reduced apoptotic gene expression and ameliorated endoplasmic reticulum stress in HG- and HM-exposed HUVECs. Thus, long-term Teneligliptin treatment reduced DPP-4 levels and activity in HUVECs exposed to chronic hyperglycemia. Moreover, Teneligliptin enhanced the beneficial effects of GLP-1 on oxidative stress, proliferation, apoptosis and endoplasmic reticulum homeostasis.

Inflammageing and metaflammation: The yin and yang of type 2 diabetes

Type 2 diabetes mellitus (T2DM) is characterised by chronic low-grade inflammation, recently referred to as 'metaflammation', a relevant factor contributing to the development of both diabetes and its complications. Nonetheless, 'canonical' anti-inflammatory drugs do not yield satisfactory results in terms of prevention of diabetes progression and of cardiovascular events, suggesting that the causal mechanisms fostering metaflammation deserve further research to identify new druggable targets. Metaflammation resembles ageing-induced low-grade inflammation, previously referred to as inflammageing, in terms of clinical presentation and the molecular profile, pointing to a common aetiology for both conditions. Along with the mechanisms proposed to fuel inflammageing, here we dissect a plethora of pathological cascades triggered by gluco- and lipotoxicity, converging on candidate phenomena possibly explaining the enduring pro-inflammatory program observed in diabetic tissues, i.e. persistent immune-system stimulation, accumulation of senescent cells, epigenetic rearrangements, and alterations in microbiota composition. We discuss the possibility of harnessing these recent discoveries in future therapies for T2DM. Moreover, we review recent evidence regarding the ability of diets and physical exercise to modulate selected inflammatory pathways relevant for the diabetic pathology. Finally, we examine the latest findings showing putative anti-inflammatory mechanisms of anti-hyperglycaemic agents with proven efficacy against T2DM-induced cardiovascular complications, in order to gain insights into quickly translatable therapeutic approaches.

Plasma kisspeptin levels are associated with insulin secretion in nondiabetic individuals

To evaluate if plasma kisspeptin concentrations are associated with insulin secretion, as suggested by recent in vitro studies, independently of confounders. 261 nondiabetic subjects were stratified into tertiles according to kisspeptin values. Insulin secretion was assessed using indexes derived from oral glucose tolerance test (OGTT). After adjusting for age, gender, and BMI, subjects in the highest (tertile 3) kisspeptin group exhibited significantly lower values of insulinogenic index, corrected insulin response (CIR₃₀), and Stumvoll indexes for first-phase and second-phase insulin release as compared with low (tertile 1) or intermediate (tertile 2) kisspeptin groups. Univariate correlations between kisspeptin concentration and metabolic variables showed that kisspeptin concentration was significantly and positively correlated with age, blood pressure, and 2-h post-load glucose, and inversely correlated with BMI, and waist circumference. There was an inverse relationship between kisspeptin levels and OGTT-derived indexes of glucose-stimulated insulin secretion. A multivariable regression analysis in a model including all the variables significantly correlated with kisspeptin concentration showed thar age (β = -0.338, P<0.0001), BMI (β = 0.272, P<0.0001), 2-h post-load glucose (β = -0.229, P<0.0001), and kisspeptin (β = -0.105, P = 0.03) remained associated with insulinogenic index. These factors explained 34.6% of the variance of the insulinogenic index. In conclusion, kisspeptin concentrations are associated with insulin secretion independently of important determinants of glucose homeostasis such as gender, age, adiposity, 2-h post-load glucose, and insulin sensitivity.

Uric Acid Is Associated With Inflammatory Biomarkers and Induces Inflammation Via Activating the NF-κB Signaling Pathway in HepG2 Cells

Objective—

Serum uric acid (UA) has been associated with increased risk of cardiovascular and metabolic diseases. However, the causal mechanisms linking elevated UA levels to cardio-metabolic diseases are still unsettled. One potential explanation for how UA might contribute to cardio-metabolic disease might be its ability to induce systemic inflammation.

Approach and Results—

Herein, we report a positive relationship between serum UA and acute-phase reactants, such as high-sensitivity C-reactive protein, fibrinogen, ferritin, complement C3, and erythrocyte sedimentation rate, in a cohort of 2731 nondiabetic adults. The relationship remains significant after adjustment for several confounders, including age, sex, adiposity, anti-hypertensive treatments or diuretics use. To confirm the existence of a causal relationship, we examined the effect of UA on the expression of inflammatory biomarkers in human hepatoma HepG2 cells and characterized the signaling pathway by which UA acts. We show that UA stimulates the expression of C-reactive protein, fibrinogen, ferritin, and complement C3 in a dose-dependent fashion. The proinflammatory effects of UA were abrogated by benzbromarone, a specific inhibitor of UA transporters. Exposure of cells to UA resulted in activation of the IκB kinase/IκBα/NF-κB signaling pathway that was attenuated by benzbromarone. The effect of UA was completely blocked by the antioxidant N -acetylcysteine.

Conclusions—

These in vivo and in vitro data suggest that hyperuricemia might induce the expression of hepatic inflammatory molecules by activating the proinflammatory NF-κB signaling cascade. Because inflammation has an important pathogenetic role in metabolic and cardiovascular disease, our study may help understanding the mechanism by which hyperuricemia may contribute to organ damage.

PHLPP phosphatases as a therapeutic target in insulin resistance-related diseases

INTRODUCTION

Pleckstrin homology domain leucine-rich repeat protein phosphatases (PHLPPs), originally identified as Akt kinase hydrophobic motif specific phosphatases, have subsequently been shown to regulate several molecules recurring within the insulin signaling pathway. This observation suggests that PHLPP phosphatases may have a clinically relevant role in the pathogenesis of insulin resistance-related diseases and may thus represent suitable targets for the treatment of these conditions.

AREAS COVERED

The literature pertaining to PHLPPs substrates is reviewed herein, along with information on the molecular players involved in regulating the activity and expression of PHLPP phosphatases. In the present review, knowledge of genetic variants in the genes that encode for PHLPP isozymes and the surrounding regulatory regions is also summarized. In addition, data from the studies addressing the role of PHLPPs in insulin resistance-related disorders and from those investigating the possibility to manipulate these phosphatases for therapeutic purposes are presented.

EXPERT OPINION

A number of issues should be resolved before PHLPPs are pursued as therapeutic targets including: the mechanisms regulating the specificity of PHLPP isozymes; the possibility of differentially regulating PHLPP family members and the possible impact of PHLPPs modulation on the risk of cancer.

SRT1720 counteracts glucosamine-induced endoplasmic reticulum stress and endothelial dysfunction

AIMS

We hypothesized that a disproportionate activation of the glucosamine (GlcN) pathway, caused by a prolonged exposure to hyperglycaemia, could impair endothelial integrity promoting endoplasmic reticulum (ER) stress. We also tested the possibility that SRT1720 may be able to counteract GlcN-induced ER stress.

METHODS AND RESULTS

Human umbilical vein endothelial cells (HUVECs), human cardiac microvascular endothelial cells, and human retinal endothelial cells were treated with GlcN in the presence or absence of the chemical chaperone phenyl butyric acid (PBA) or SRT1720. Expression of ER stress markers, activation of apoptosis, and pro-inflammatory/pro-thrombotic pathways were evaluated by western blot, real-time RT-PCR, and ELISA assays. GlcN treatment resulted in a significantly increased expression of the major ER stress mediators. ER stress activation was paralleled by increased levels of apoptotic markers and by pro-inflammatory/pro-coagulant pathway activation. In HUVECs, ER stress inhibition by PBA alleviated a GlcN-induced pro-apoptotic and pro-inflammatory/pro-thrombotic state, suggesting a crucial role of ER stress in endothelial dysfunction caused by GlcN. Furthermore, SRT1720 treatment abolished GlcN-induced ER stress and reversed its effects on apoptosis and pro-inflammatory/pro-coagulant pathways. This SRT1720 action was mediated by its ability to modulate Raptor acetylation, thus inhibiting mammalian target of Rapamycin complex 1 (mTORC1)-dependent protein synthesis and alleviating ER overload.

CONCLUSIONS

Our data show that GlcN promotes a pro-apoptotic and pro-inflammatory/pro-thrombotic phenotype in endothelial cells by activating ER stress. The observation that SRT1720, inhibiting ER stress, was able to counteract GlcN effects lays the basis for future studies aimed to exploit this drug and cognate compounds in the treatment of endothelial dysfunction and atherosclerosis.

Orthopaedic management of haemophilia arthropathy of the ankle

Joint bleeding, or haemarthrosis, is the most common type of bleeding episode experienced by individuals with haemophilia A and B. This leads to changes within the joints, including synovial proliferation, which results in further bleeding and chronic synovitis. Blood in the joint can also directly damage the cartilage, and with repeated bleeding, there is progressive destruction of both cartilage and bone. The end result is known as haemophilic arthropathy. The joints most commonly affected are the knees, elbows and ankles, although any synovial joint may be involved. In the ankle, both the tibiotalar and subtalar joints may be affected and joint bleeding and arthropathy can lead to a number of deformities. Haemophilic arthropathy can be prevented through regular factor replacement prophylaxis and implementing physiotherapy. However, when necessary, there are multiple surgical and non-surgical options available. In early ankle arthropathy with absent or minimal joint changes, both radioisotopic and chemical synoviorthesis can be used to reduce the hypertrophied synovium. These procedures can decrease the frequency of bleeding episodes, minimizing the risk of articular cartilage damage. Achilles tendon lengthening can be performed, in isolation or in combination with other surgical measures, to correct Achilles tendon contractures. Both arthroscopic and open synovectomies are available as a means to remove the friable villous layer of the synovium and are often indicated when bleeding episodes cannot be properly controlled by factor replacement therapy or synoviorthesis. In the later stages of ankle arthropathy, other surgical options may be considered. Debridement may be indicated when there are loose pieces of cartilage or anterior osteophytes, and can help to improve the joint function, even in the presence of articular cartilage damage. Supramalleolar tibial osteotomy may be indicated in patients with a valgus deformity of the hindfoot without degenerative radiographic findings. Joint fusion, or arthrodesis, is the treatment of choice in the advanced stages of ankle arthropathy although total ankle replacement is currently available. Early ankle replacement components were associated with a poor outcome, but as implant designs have improved, there have been successful outcomes achieved. As the ankle is a commonly affected joint in many individuals with haemophilia, it is important to add to the knowledge base to validate indications and timing of surgical and non-surgical interventions in ankle arthropathy.

Activity of lavandino essential oil against non-tubercular opportunistic rapid grown mycobacteria

Four samples of lavandino essential oil were investigated for their antimycobacterial activity, and were found to be very effective against some strains of non-tubercolar Mycobacteria (NTM). The mechanism of this effect is discussed.

US Court of Appeals decision regarding Armstrong v. Kline: the 180 day rule

On June 21, 1979, Judge Clarence C. Newcomer, of the United States District Court for the Eastern District of Pennsylvania, issued his decision and Order in the case of Armstrong v. Kline. Judge Newcomer held that the undisputed policy and practice of the Pennsylvania Department of Education of refusing to provide or fund the provision of a program of special education and related services in excess of 180 days per year to any handicapped student was in violation of Public Law 94-142. Also held to be in violation of the law was the Department's companion policy of instructing all hearing officers who preside at special education due process hearings that they were without the power to order or approve any educational programs exceeding 180 days per year. On July 15, 1980, the Appellate Court upheld the District Court in three separate opinions. This article describes the decision of the District Court, explains how the reasoning of the Appellate Court differs, and points out some of the implications of the Appellate Court's holding.