Association of Adipokines with Insulin Resistance, Microvascular Dysfunction, and Endothelial Dysfunction in Healthy Young Adults

Plasminogen Activator Inhibitor-1 in the Pathophysiology of Late Life Depression

INTRODUCTION

Late life depression (LLD) is characterized by specific clinical features including a high frequency of vascular form and frequent antidepressant treatment resistance. The expression and functions of the serine protease inhibitor, Plasminogen Activator Inhibitor-1 (PAI-1) is known to be altered by aging, vascular damage, insulin levels associated with a sedentary lifestyle, chronic stress leading to hypercortisolemia, and inflammatory changes linked to stress responses. These phenomena would be implicated in LLD like vascular depression. This article thus aims to review the existing literature regarding the association between LLD and plasmatic levels of PAI-1, a marker of hypofibrinolysis. We hypothesize that increased age would be associated with changes in PAI-1 plasma level and function which influence LLD pathogenesis and its treatment.

RESULTS

Although a large number of studies on PAI-1 changes in the elderly exist, studies about its implications in LLD are sparse. Despite heterogeneous findings regarding the direction of variation in plasmatic PAI-1 levels among elderly participants with LLD, all studies demonstrated an association between PAI-1 levels and current or remitted depressive symptoms. Moreover, disruptions in the concentrations of other biological markers influencing PAI-1 expression, such as cytokines or adipokines, were also observed, notably an increase in the levels of interleukins 6 and 8.

DISCUSSION

LLD genesis appears to be influenced by PAI-1 regulatory loops which are implicated in senescence or cell death. The resistance to antidepressant treatment appears to be linked to distinct biological profiles involving inflammatory and fibrinolytic factors. Taken together these data suggest that PAI-1 pathway may be a promising target of treatment development efforts for LLD, and depression in general.

HOMA-IR as a Predictor of PAI-1 Levels in Women with Severe Obesity

BACKGROUND

Obesity is a chronic inflammatory disorder that increases the risk of cardiovascular diseases (CVDs). Given the high CVD mortality rate among individuals with obesity, early screening should be considered. Plasminogen activator inhibitor (PAI-1), a cytokine that links obesity and CVDs, represents a promising biomarker. However, PAI-1 is not part of the clinical routine due to its high cost. Therefore, it is necessary to find good predictors that would allow an indirect assessment of PAI-1.

METHODS

This study enrolled 47 women with severe obesity (SO). The obtained anthropometric measurements included weight, height, neck (NC), waist (WC), and hip circumference (HC). Blood samples were collected to analyse glucose and lipid profiles, C-reactive protein, liver markers, adiponectin, and PAI-1 (determined by ELISA immunoassay). Homeostasis model assessment-adiponectin (HOMA-AD), homeostasis model assessment of insulin resistance (HOMA-IR), quantitative insulin sensitivity check index (QUICKI), triglyceride-glucose index (TyG), and atherogenic index of plasma (AIP) were calculated. The women were grouped according to PAI-1 levels. The data were analysed using IBM SPSS Statistics, version 21. The significance level for the analysis was set at 5%.

RESULTS

Women with SO who have higher levels of PAI-1 have lower values of high-density lipoprotein cholesterol (HDL) (p = 0.037) and QUICKI (0.020) and higher values of HOMA-AD (0.046) and HOMA-IR (0.037). HOMA-IR was demonstrated to be a good predictor of PAI-1 in this sample (B = 0.2791; p = 0.017).

CONCLUSIONS

HOMA-IR could be used as a predictor of PAI-1 levels, pointing out the relevance of assessing glycaemic parameters for the prevention of CVDs in women with SO.

Adipose Tissue Hypoxia in Obesity: Clinical Reappraisal of Hypoxia Hypothesis

Obese subjects exhibit lower adipose tissue oxygen consumption in accordance with the lower adipose tissue blood flow. Thereby, compared to lean subjects, obese individuals have almost half lower capillary density and more than half lower vascular endothelial growth factor (VEGF). The VEGF expression together with hypoxia-inducible transcription factor-1 alpha (HIF-1α) activity also requires phosphatidylinositol 3-kinase (PI3K) and mammalian target of rapamycin (mTOR)-mediated signaling. Especially HIF-1α is an important signaling molecule for hypoxia to induce the inflammatory responses. Hypoxia contributes to several biological functions, such as angiogenesis, cell proliferation, apoptosis, inflammation, and insulin resistance (IR). Pathogenesis of obesity-related comorbidities is attributed to intermittent hypoxia (IH), which is mostly observed in visceral obesity. Proinflammatory phenotype of the adipose tissue is a crucial link between IH and the development of IR. Inhibition of adaptive unfolded protein response (UPR) in hypoxia increases β cell death. Moreover, deletion of HIF-1α worsens β cell function. Oxidative stress, as well as the release of proinflammatory cytokines/adipokines in obesity, is proportional to the severity of IH. Reactive oxygen species (ROS) generation at mitochondria is responsible for propagation of the hypoxic signal; however, mitochondrial ROS production is required for hypoxic HIF-1α protein stabilization. Alterations in oxygen availability of adipose tissue directly affect the macrophage polarization and are responsible for the dysregulated adipocytokines production in obesity. Hypoxia both inhibits adipocyte differentiation from preadipocytes and macrophage migration from the hypoxic adipose tissue. Upon reaching a hypertrophic threshold beyond the adipocyte fat loading capacity, excess extracellular matrix (ECM) components are deposited, causing fibrosis. HIF-1α initiates the whole pathological process of fibrosis and inflammation in the obese adipose tissue. In addition to stressed adipocytes, hypoxia contributes to immune cell migration and activation which further aggravates adipose tissue fibrosis. Therefore, targeting HIF-1α might be an efficient way to suppress hypoxia-induced pathological changes in the ECM. The fibrosis score of adipose tissue correlates negatively with the body mass index and metabolic parameters. Inducers of browning/beiging adipocytes and adipokines, as well as modulations of matrix remodeling enzyme inhibitors, and associated gene regulators, are potential pharmacological targets for treating obesity.

Obesity-Related Inflammation and Endothelial Dysfunction in COVID-19: Impact on Disease Severity

The coronavirus disease 2019 (COVID-19) pandemic has put into evidence another pandemic – obesity. Currently, several studies have documented the association between obesity and COVID-19 severity. The mechanisms underlying the increased risk of complications and mortality in obese patients with COVID-19 are of diverse nature. Inflammation plays a central role in obesity. Metabolic alterations seen in obese patients are related to an inflammatory response, and several studies report elevated levels of circulating inflammatory cytokines in obese patients. Also, deregulated expression of adipokines, such as leptin and resistin, increase the expression of vascular adhesion molecule 1 and intercellular adhesion molecule 1 that contribute to increased vascular leukocyte adhesiveness and additional oxidative stress. Additionally, it is now recognized that the chronic impairment of systemic vascular endothelial function in patients with cardiovascular and metabolic disorders, including obesity, when intensified by the detrimental effects of SARS-CoV-2 over the endothelium, may explain their worse outcomes in COVID-19. In fact, vascular endothelial dysfunction may contribute to a unfavorable response of the endothelium to the infection by SARS-CoV-2, whereas alterations in cardiac structure and function and the prothrombotic environment in obesity may also provide a link to the increased cardiovascular events in these patients.

ApoA-I Mimetic Peptide Reduces Vascular and White Matter Damage After Stroke in Type-2 Diabetic Mice

Diabetes leads to an elevated risk of stroke and worse functional outcome compared to the general population. We investigate whether L-4F, an economical ApoA-I mimetic peptide, reduces neurovascular and white-matter damage in db/db type-2 diabetic (T2DM) stroke mice. L-4F (16 mg/kg, subcutaneously administered initially 2 h after stroke and subsequently daily for 4 days) reduced hemorrhagic transformation, decreased infarct-volume and mortality, and treated mice exhibited increased cerebral arteriole diameter and smooth muscle cell number, decreased blood-brain barrier leakage and white-matter damage in the ischemic brain as well as improved neurological functional outcome after stroke compared with vehicle-control T2DM mice (p < 0.05, n = 11/group). Moreover, administration of L-4F mitigated macrophage infiltration, and reduced the level of proinflammatory mediators tumor necrosis factor alpha (TNFα), high-mobility group box-1 (HMGB-1)/advanced glycation end-product receptor (RAGE) and plasminogen activator inhibitor-1 (PAI-1) in the ischemic brain in T2DM mice (p < 0.05, n = 6/group). In vitro, L-4F treatment did not increase capillary-like tube formation in mouse-brain endothelial cells, but increased primary artery explant cell migration derived from C57BL/6-aorta 1 day after middle cerebral artery occlusion (MCAo), and enhanced neurite-outgrowth after 2 h of oxygen-glucose deprivation and axonal-outgrowth in primary cortical neurons derived from the C57BL/6-embryos subjected to high-glucose condition. This study suggests that early treatment with L-4F provides a potential strategy to reduce neuroinflammation and vascular and white-matter damage in the T2DM stroke population.

Dermal capillary rarefaction as a marker of microvascular damage in patients with rheumatoid arthritis: Association with inflammation and disorders of the macrocirculation

OBJECTIVE

Capillary rarefaction is observed in various cardiovascular diseases, yet it remains understudied in RA, a chronic inflammatory disease accompanied by excess cardiovascular risk. We quantified capillary density in RA patients and explored potential associations with macrocirculatory disorders, inflammation, and cardiovascular risk.

METHODS

Dermal capillary density was assessed with nailfold capillaroscopy in RA and non-RA individuals, using specifically designed semiautomated software. Macrocirculation assessments included large artery stiffening, evaluated with PWV, and myocardial blood flow, calculated as cardiac index from impedance cardiography. Cardiovascular risk score was estimated from the Framingham Heart Study.

RESULTS

The number of capillaries per visual field was lower in patients (n = 99) compared to controls (n = 35) (132.6 ± 30.3 vs 152.9 ± 25.2, P = .001). In the RA group, capillary density negatively correlated with CRP and PWV, and positively with HDL and cardiac index. In the multivariate analysis, CRP independently predicted capillary rarefaction (P = .044). Capillary density significantly correlated with cardiovascular risk, even after adjustment for inflammation (P = .030).

CONCLUSION

Capillary rarefaction appears pronounced in RA and correlates with lower cardiac output, increased arterial stiffness, and cardiovascular risk. However, the associations with macrocirculatory disorders may be obscured by inflammation, which appears as the major contributor to capillary rarefaction in RA.

Role of adipocytokines in the pathophysiology of migraine: A cross-sectional study

Background Obesity is a risk factor for migraine and headache chronification. Adipocytokines may be involved in this correlation. Objective To relate serum adipocytokine levels to clinical and biochemical parameters associated with migraine. Methods We measured levels of leptin, adiponectin and other inflammatory (interleukin 6, interleukin 10, tumor necrosis factor α, high sensitivity C-reactive protein) and endothelial (pentraxin 3, soluble TNF-like weak inducer of apoptosis) molecules potentially related to migraine pathophysiology in a group of migraine patients (IHS 2013) and healthy controls. Results One hundred and eleven patients (mean age 39.7 years, 93% female) and 24 healthy controls (mean age 35.9 years, 90% female) were included. Fifty-six patients were diagnosed with episodic migraine (mean age 35.1 years, 98.2% female) and 55 patients with chronic migraine (mean age 44.4 years, 89.5% female). Leptin serum levels (15.2 ng/mL, SD = 10.5 vs . 3.1 ng/mL, SD = 0.9; p < 0.001) and adiponectin serum levels (72.3 µg/mL, SD = 38.5 vs . 37.7 µg/mL, SD = 16.9; p < 0.001) were significantly increased in migraine patients. Leptin serum levels (15.5 ng/mL, SD = 9.7 vs . 10.8 ng/mL, SD = 6.0; p < 0.001) and adiponectin serum levels (65.8 µg/mL, SD = 42.9 vs . 33.2 µg/mL, SD = 31.0; p < 0.001) were significantly higher in chronic compared to episodic migraine patients. We found a positive correlation between leptin levels and inflammatory biomarkers: IL6 (r = 0.498; p < 0.001), TNF-α (r = 0.389; p < 0.001), and hs-CRP (r = 0.422; p < 0.001). Conclusions Leptin and adiponectin are increased in migraineurs. There is a correlation between adipocytokine levels and other inflammation-related molecules. This suggests a potential role of adipocytokines in migraine pathophysiology and chronification.

Adipose Tissue Hypoxia in Obesity and Its Impact on Preadipocytes and Macrophages: Hypoxia Hypothesis

Obese subjects exhibit lower adipose tissue oxygen consumption in accordance with the lower adipose tissue blood flow. Thus, compared with lean subjects, obese subjects have 44% lower capillary density and 58% lower vascular endothelial growth factor (VEGF). The VEGF expression together with hypoxia-inducible transcription factor-1 (HIF-1) activity also requires phosphatidylinositol 3-kinase (PI3K)- and target of rapamycin (TOR)-mediated signaling. HIF-1alpha is an important signaling molecule for hypoxia to induce the inflammatory responses. Hypoxia affects a number of biological functions, such as angiogenesis, cell proliferation, apoptosis, inflammation and insulin resistance. Additionally, reactive oxygen radical (ROS) generation at mitochondria is responsible for propagation of the hypoxic signal. Actually mitochondrial ROS (mtROS) production, but not oxygen consumption is required for hypoxic HIF-1alpha protein stabilization. Adipocyte mitochondrial oxidative capacity is reduced in obese compared with non-obese adults. In this respect, mitochondrial dysfunction of adipocyte is associated with the overall adiposity. Furthermore, hypoxia also inhibits macrophage migration from the hypoxic adipose tissue. Alterations in oxygen availability of adipose tissue directly affect the macrophage polarization and are responsible from dysregulated adipocytokines production in obesity. Hypoxia also inhibits adipocyte differentiation from preadipocytes. In addition to stressed adipocytes, hypoxia contributes to immune cell immigration and activation which further aggravates adipose tissue fibrosis. Fibrosis is initiated in response to adipocyte hypertrophy in obesity.

Impaired metabolic profile is a predictor of capillary rarefaction in a population of hypertensive and normotensive individuals

Capillary rarefaction is typically encountered in essential hypertension, yet identification of factors interfering with this phenomenon remains substantially underinvestigated. We examined whether components of metabolic profile (dyslipidemia, insulin resistance), inflammatory (high-sensitivity C-reactive protein, high-sensitivity C-reactive protein), and angiogenic (vascular endothelial growth factor) factors are implicated in this phenomenon in a population of newly diagnosed, never-treated hypertensive patients and normotensive controls. Nailfold capillary density was estimated with nailfold capillaroscopy using specifically designed software. A total of 159 individuals, 93 hypertensives, and 66 normotensives were included. Nailfold capillary density was lower among hypertensives compared to normotensives (146.4 ± 31.0 vs. 155.4 ± 26.9, respectively; P = .047). In the total population, capillary density significantly correlated with high-density lipoprotein (HDL) (r = 0.232; P = .003), HDL/low-density lipoprotein ratio (r = 0.175; P = .025), age (r = 0.236; P = .003), but neither with vascular endothelial growth factor or high-sensitivity C-reactive protein. An inverse association was found with body mass index (r = -0.174; P = .029), insulin levels (r = -0.200; P = .018), and homeostasis model assessment-insulin resistance (r = -0.223; P = .009). In the separate analysis for the hypertensive population, sex (P = .014) and homeostasis model assessment-insulin resistance (P = .011) were identified as significant predictors of capillary rarefaction after adjustment for other factors. On the contrary, only HDL levels (P = .036) predicted capillary density in the multiple regression model for the normotensive population. Different aspects of impaired metabolic profile, that is, insulin resistance and low HDL levels, but not angiogenic or inflammatory markers, appear to be independently associated with capillary rarefaction in hypertensive and normotensive individuals.

Inverse Relationship of the CMKLR1 Relative Expression and Chemerin Serum Levels in Obesity with Dysmetabolic Phenotype and Insulin Resistance

Background. In obesity there is a subclinical chronic low-grade inflammatory response where insulin resistance (IR) may develop. Chemerin is secreted in white adipose tissue and promotes low-grade inflammatory process, where it expressed CMKLR1 receptor. The role of chemerin and CMKLR1 in inflammatory process secondary to obesity is not defined yet. Methods. Cross-sectional study with 134 individuals classified as with and without obesity by body mass index (BMI) and IR. Body fat storage measurements and metabolic and inflammatory markers were measured by routine methods. Soluble chemerin and basal levels of insulin by ELISA and relative expression of CMKLR1 were evaluated with qPCR and 2^−ΔΔC_T method. Results. Differences (P < 0.05) were observed between obesity and lean individuals in body fat storage measurements and metabolic-inflammatory markers. Both CMKLR1 expression and chemerin levels were increased in obesity without IR. Soluble chemerin levels correlate with adiposity and metabolic markers (r = 8.8% to 38.5%), P < 0.05. Conclusion. The increment of CMKLR1 expression was associated with insulin production. Increased serum levels of chemerin in obesity were observed, favoring a dysmetabolic response. The results observed in this study suggest that both chemerin and CMKLR1 have opposite expression in the context of low-grade inflammatory response manifested in the development of IR.