Enhancement of lipopolysaccharide-induced toll-like receptor 2 expression and inflammatory cytokine secretion in HUVECs under high glucose conditions

Dapagliflozin exerts anti-inflammatory effects via inhibition of LPS-induced TLR-4 overexpression and NF-κB activation in human endothelial cells and differentiated macrophages

Evidence has demonstrated that a new class of anti-diabetic drugs, sodium-glucose co-transporter 2 (SGLT2) inhibitors, could exert beneficial effects on atherosclerotic complications of diabetes. Atherosclerosis is widely accepted as an inflammatory disease. Therefore, we aimed to assess the direct anti-inflammatory effects of SGLT2 inhibitors dapagliflozin (DAPA) on two cell types involved in the process of atherogenesis. Human umbilical vein endothelial cells (HUVECs) and macrophages were exposed to DAPA and lipopolysaccharide (LPS 20 ng/mL) for 24 h under normal (5.5 mmol/L, NG) or high glucose (25 mmol/L, HG) conditions. Then, levels of TLR-4/p-NF-κB, inflammatory cytokines, inflammation-related miR-146a and miR-155 as well as alteration in the ratio of M1/M2 macrophage polarization was assessed. DAPA (0.5 μM) could significantly attenuate LPS-induced TLR-4 overexpression (23.9% and 33.1% under NG and HG conditions in HUVECs and 53.3% and 52.4% under NG and HG states in macrophages, respectively). NF-κB p65 phosphorylation was also significantly decreased to 30.1% under NG condition in HUVECs and 51.9% and 34.5% under NG and HG states in macrophages by 0.5 μM DAPA. Moreover, DAPA elevated expression levels of anti-inflammatory miR-146a, while values of miR-155 decreased in those cells. DAPA also caused a shift from inflammatory M1 macrophages toward M2-dominant macrophages. These data suggest that regardless of glucose concentrations, DAPA could exert direct anti-inflammatory effects, at least partly, by inhibiting the expression of TLR-4 and activation of NF-κB along with the secretion of pro-inflammatory mediators.

Periodontitis and Gestational Diabetes Mellitus: A Potential Inflammatory Vicious Cycle

Periodontitis is a chronic inflammatory immune disease associated with a dysbiotic state, influenced by keystone bacterial species responsible for disrupting the periodontal tissue homeostasis. Furthermore, the severity of periodontitis is determined by the interaction between the immune cell response in front of periodontitis-associated species, which leads to the destruction of supporting periodontal tissues and tooth loss in a susceptible host. The persistent bacterial challenge induces modifications in the permeability and ulceration of the sulcular epithelium, which facilitates the systemic translocation of periodontitis-associated bacteria into distant tissues and organs. This stimulates the secretion of pro-inflammatory molecules and a chronic activation of immune cells, contributing to a systemic pro-inflammatory status that has been linked with a higher risk of several systemic diseases, such as type 2 diabetes mellitus (T2DM) and gestational diabetes mellitus (GDM). Although periodontitis and GDM share the common feature of systemic inflammation, the molecular mechanistic link of this association has not been completely clarified. This review aims to examine the potential biological mechanisms involved in the association between periodontitis and GDM, highlighting the contribution of both diseases to systemic inflammation and the role of new molecular participants, such as extracellular vesicles and non-coding RNAs, which could act as novel molecular intercellular linkers between periodontal and placental tissues.

Renal dysfunction in a mouse model of GDM is prevented by metformin through MAPKs

Gestational diabetes mellitus (GDM) incidence is increasing worldwide. In the present study, the effects of metformin on high fat diet (HFD)‑induced renal dysfunction were investigated in GDM mice. In addition, the molecular mechanisms underlying metformin function were examined. GDM was induced by feeding pregnant mice a HFD, and mice were treated with two different doses of metformin (300 and 600 mg/kg/day) or PBS between embryonic day 11.5 (E11.5) and E17.5. The pregnant mice at E18.5 were utilized to analyze the effects of metformin on renal dysfunction. Renal function and the protein expression levels of inflammatory cytokines and factors of the mitogen‑activated protein kinase (MAPK) signaling pathway in the kidneys of pregnant mice were assessed by ELISA and western blotting. Data obtained during late pregnancy suggested that metformin significantly decreased body weight and the levels of blood glucose in GDM mice, as assessed by the glucose tolerance test and the homeostatic model assessment for insulin resistance. The levels of microalbumin and serum β2‑microglobulin in GDM mice during late pregnancy were decreased following treatment with metformin. Furthermore, serum levels of interleukin (IL)‑6 and tumor necrosis factor (TNF)‑α, and phosphorylation of MAPK1/3, MAPK14 and MAPK8 in the kidneys were decreased in GDM mice following metformin treatment at E18.5, compared with the untreated GDM group. The present study suggested that inflammation may be associated with renal dysfunction in GDM mice, and that the MAPK signaling pathway may be involved in the protective effect of metformin on renal dysfunction in GDM mice.

[Exogenous agmatine inhibits lipopolysaccharide-induced activation and dysfunction of human umbilical vein endothelial cells]

OBJECTIVE

To investigate whether exogenous agmatine inhibits lipopolysaccharide (LPS)-induced activation and dysfunction of human umbilical vein endothelial cells (HUVECs) by modulating nuclear factor-κB (NF-κB) and MAPK signal pathways and the production of reactive oxygen species (ROS).

METHODS

Cultured HUVECs were treated with agmatine at the optimized concentration of 1.0 mmolγL, LPS (10 µgγmL), and LPS + agmatine, with or without pretreatment with the inhibitors of NF-κB (PDTC), p38 (SB203580), and ERK (PD98059) for 1 h. The levels of soluble vascular cell adhesion molecule 1 (VCAM-1), soluble intercellular adhesion molecule 1 (sICAM-1), soluble E-selectin and monocyte chemoattractant protein 1 (MCP-1) in the supernatant were determined using ELISA, and their mRNA expressions, along with heme oxygenase-1 (HO-1), and NAD(P)H: quinone oxidoreductase 1 (NQO-1), were assessed using real-time PCR. ROS production in the cells was determined using 2, 7-dichlorofluoresce in diacetate (DCFH-DA) as the fluorescence probe. The protein expressions of VCAM-1, ICAM-1, p65, phospho-p65 (p-p65), IκBα, p-IκBα, ERK, p-ERK, p38, p-p38, JNK, and p-JNK were detected using Western blotting.

RESULTS

LPS stimulation for 6 and 24 h significantly increased the levels of sVCAM-1, sICAM-1, sE-selectin and MCP-1 in the supernatant, intracellular ROS production, and the mRNA expressions of these molecules (P<0.05). Intervention with 1 mmolγL agmatine, similar with pretreatment with p38, ERK and NF-κB inhibitors, obviously inhibited such effects of LPS in HUVECs (P<0.05). Agmatine significantly up-regulated the mRNA expression of HO-1 (P<0.05), inhibited LPS-induced phosphorylation of p38, ERK, nuclear p65 and cytoplasmic IκBα, and up-regulated the protein expression of cytoplasmic IκBα.

CONCLUSION

Agmatine inhibits LPS-induced activation and dysfunction of HUVECs by modulating NF-κB and MAPK signal pathways to down-regulate the expressions of adhesion molecules and chemokines and by up-regulating the expression of HO-1 to reduce ROS production.

Role of Exosomes in Placental Homeostasis and Pregnancy Disorders

The human placenta is a unique organ that performs the function of the majority of fetal organs across gestation. How the placenta communicates with maternal tissues to prepare them for pregnancy is not fully understood. Recently, it has been established that placental cells can communicate with maternal tissues to regulate their biological function via extracellular vesicles (EVs). EVs are subclassified into exosomes or microvesicles (MVs) according to their size, cell or tissue of origin, functions, and physical features. Exosomes are a specific type of EVs from an endocytic origin, while MVs are released via budding from the plasma membrane. With regards to pregnancy, the role of EVs has been described in several functions such as immune responses and maternal metabolic adaptation to gestation. Interestingly, EVs of placental origin can be detected in a variety of body fluids including urine and blood, and have been identified in the maternal circulation at as early as 6 weeks of gestation. Moreover, the number of exosomes across gestation is higher in complications of pregnancies such as preeclampsia and gestational diabetes mellitus compared to normal pregnancies. Circulating exosomes contains proteins and RNAs that are representative of the cell of origin, including surface and cytoplasmic protein, messenger RNA, and micro-RNAs. Finally, exosomes are capable of transferring their contents to other cells and regulating the biological function of the target cell. In this review, we will discuss the effect of the maternal microenvironment on secretion and content of placenta-derived EVs, and how this may lead to complications of pregnancies with a special emphasis on exosomes.

Hyperglycemia Induces Toll-Like Receptor Activity Through Increased Oxidative Stress

Hyperglycemia-induced oxidative stress and inflammation are central in the genesis of diabetic vascular complications. Toll-like receptors (TLRs) play a crucial role in promoting inflammatory responses and are known to be activated in diabetic patients. Also in animal models, they have been shown to have a role in the pathogenesis of diabetic vasculopathies. However, the mechanisms underlying this increase in TLR activity in diabetes are not well documented. Since increased reactive oxygen species (ROS) are also produced in various tissues under diabetic conditions, we postulated that ROS act as a potential activator of TLR. Several studies support our hypothesis that hyperglycemia-induced oxidative stress appears to be an important factor in promoting TLR activity in monocytes, both microvascular and macrovascular endothelial cells and cardiomyocytes and in animal models. Most importantly, the increase in ROS and TLR activity is ameliorated with antioxidant strategies. Thus, targeting ROS/NADPH oxidase with small molecular inhibitors could be a promising strategy to reduce both oxidative stress and TLR-mediated inflammation in diabetic vascular diseases.

Modulation of endothelial function by Toll like receptors

Endothelial cells (EC) are able to actively control vascular permeability, coagulation, blood pressure and angiogenesis. Most recently, a role for endothelial cells in the immune response has been described. Therefore, the endothelium has a dual role controlling homeostasis but also being the first line for host defence and tissue damage repair thanks to its ability to mount an inflammatory response. Endothelial cells have been shown to express pattern-recognition receptors (PRR) including Toll-like receptors (TLR) that are activated in response to stimuli within the bloodstream including pathogens and damage signals. TLRs are strategic mediators of the immune response in endothelial cells but they also regulate the angiogenic process critical for tissue repair. Nevertheless, endothelial activation and angiogenesis can contribute to some pathologies. Thus, inappropriate endothelial activation, also known as endothelial dysfunction, through TLRs contributes to tissue damage during autoimmune and inflammatory diseases such as atherosclerosis, hypertension, ischemia and diabetes associated cardiovascular diseases. Also TLR induced angiogenesis is required for the growth of some tumors, atherosclerosis and rheumatoid arthritis, among others. In this review we discuss the importance of various TLRs in modulating the activation of endothelial cells and their importance in immunity to infection and vascular disease as well as their potential as therapeutic targets.

Gestational Diabetes Mellitus Is Associated With Changes in the Concentration and Bioactivity of Placenta-Derived Exosomes in Maternal Circulation Across Gestation

Although there is significant interest in elucidating the role of placenta-derived exosomes (PdEs) during pregnancy, the exosomal profile in pregnancies complicated by gestational diabetes mellitus (GDM) remains to be established. The aim of this study was to compare the gestational-age profile of PdEs in maternal plasma of GDM with normal pregnancies and to determine the effect of exosomes on cytokine release from human umbilical vein endothelial cells. A prospective cohort of patients was sampled at three time points during pregnancy for each patient (i.e., 11-14, 22-24, and 32-36 weeks' gestation). A retrospective stratified study design was used to quantify exosomes present in maternal plasma of normal (n = 13) and GDM (n = 7) pregnancies. Gestational age and pregnancy status were identified as significant factors contributing to variation in plasma exosome concentration (ANOVA, P < 0.05). Post hoc analyses established that PdE concentration increased during gestation in both normal and GDM pregnancies; however, the increase was significantly greater in GDM (∼2.2-fold, ∼1.5-fold, and ∼1.8-fold greater at each gestational age compared with normal pregnancies). Exosomes isolated from GDM pregnancies significantly increased the release of proinflammatory cytokines from endothelial cells. Although the role of exosomes during GDM remains to be fully elucidated, exosome profiles may be of diagnostic utility for screening asymptomatic populations.

Beneficial effects of evodiamine on P2X(4)-mediated inflammatory injury of human umbilical vein endothelial cells due to high glucose

Evodiamine has been reported to exhibit anti-inflammatory and anti-nociceptive effects, but the underlying mechanisms remain to be defined. P2X4 receptor (P2X4R) is a subtype of ATP receptors and plays important roles in pain, inflammatory and immune responses. We aimed to investigate whether evodiamine has beneficial effects on endothelial inflammatory injury mediated by chronic high glucose condition. We found that culturing human umbilical vein endothelial cells (HUVECs) with high glucose significantly increased the expression of P2X4 receptor in HUVECs, cytosolic Ca(2+) concentrations and intracellular reactive oxygen species (ROS) while decreasing nitric oxide (NO); these effects could be reversed by evodiamine. High glucose also significantly increased the expression of the pro-inflammatory activators (NF-κB) and TNFR-ɑ, which was accompanied by the elevation of P2X4R levels. Evodiamine was able to down-regulate the elevated NF-κB, TNFR-ɑ, P2X4R and ROS, and up-regulate the decreased NO. Thus the evodiamine may exert the anti-inflammation activity on high-glucose challenge HUVEC via suppressing the P2X4R signaling pathway, exhibiting beneficial ability to protect HUVECs from glucotoxicity.

TLR2 expression doesn't change in ox-LDL mediated inflammation in Human umbilical vein endothelial cells under high glucose culture

BACKGROUND

Inflammatory responses induced by ox-LDL play important roles in atherogenesis, and could be promoted in diabetic patients. Toll-like receptor (TLR)2 is an innate inflammatory receptor, and is enhanced in human umbilical vein endothelial cells (HUVECs) under high glucose conditions. Ox-LDL-TLR2 pathway activation and further inflammation in monocytes are involved in the atherosclerosis formation.

OBJECTIVE

What role of TLR2 plays on ox-LDL-induced inflammation in HUVECs remains unclear, especially in high glucose conditions. The purpose of this study is to explore the effect and role of ox-LDL-TLR2 pathway on the inflammatory responses in HUVECs.

METHODS

1 hour prior to the treatment, HUVECs were treated with or without neutralizing anti-TLR2 antibody. After that, HUVECs were treated with ox-LDL (20, or 40 μg/ml) or LPS (200 ng/ml) under normal and high glucose conditions. The expressions of ICAM-1 and TLR2 protein were analyzed by immunoblotting, and IL-6 and IL-8 were measured by ELISA.

RESULTS

Compared with those in normal glucose condition, IL-6 and IL-8 expression were increased in high glucose condition. The stimulation of ox-LDL and LPS both increased the expression of ICAM-1, IL-6 and IL-8, but did not change TLR2 protein expression in both normal and high glucose conditions. Additionally, the expression of ICAM-1, IL-6 and IL-8 was not changed when TLR2 was knocked out under these two conditions.

CONCLUSION

The inflammatory responses induced by Ox-LDL were not changed with or without TLR2 under both normal and high glucose conditions in HUVECs. Our study indicates TLR2 is not involved in the ox-LDL mediated endothelial injury under high glucose conditions, which is an important step of atherosclerosis formation in diabetes.

The serum from dialysis patients with acute coronary syndrome up-regulates the expression of TLR2 and its downstream effectors in human renal glomerular endothelial cells

BACKGROUND

This study was to investigate the expression of toll-like receptor 2 and its downstream effectors in endothelial cells in response to the serum from maintenance hemodialysis (MHD) patients with acute coronary syndrome (ACS).

METHODS

Human renal glomerular endothelial cells (HRGEC) were treated in vitro with serum from the healthy subjects (control group), the MHD patients with stable angina pectoris (SAP group), or the MHD patients with ACS (ACS group). The cells in ACS group were cultured in the presence or absence of TLR2 signaling blockers for 18 h. The mRNA level for TLR2, nuclear factor-κB (NF-κB), interleukin-6 (IL-6) and vascular cell adhesion molecule-1 (VCAM-1) were examined by real-time qPCR, the localization of TLR2 was detected by immunocytochemistry, and the secretion of IL-6 and VCAM-1 were measured by enzyme-linked immunosorbent assay.

RESULTS

The mRNA level of TLR2, NF-κB and IL-6 were statistically higher in the ACS group when compared with those in SAP group and healthy controls (p < 0.05), but not significantly different between SAP and healthy controls. The secretion of IL-6 in ACS group was increased when compared with SAP group and control subjects (p < 0.05). When the HRGEC were cultured with the anti-TLR2 antibodies, the expression of NF-κB, IL-6 and VCAM-1 mRNA as well as the secretion of IL-6 and VCAM-1 were significantly inhibited (p < 0.05).

CONCLUSION

This study revealed that the TLR2 signaling may mediate pro-inflammatory response in the MHD patients occurring with ACS.

In vitro evaluation of defined oligosaccharide fractions in an equine model of inflammation

BACKGROUND

Dietary supplementation with oligosaccharides has been proven to be beneficial for health in several mammalian species. Next to prebiotic effects resulting in a modulation of gut micro biota, immunomodulatory effects of oligosaccharides have been documented in vivo. Supplementation with defined oligosaccharide fractions has been shown to attenuate allergic responses and enhance defensive immune responses. Despite the accumulating evidence for immunomodulatory effects, very limited information is available regarding the direct mechanism of action of oligosaccharides. This study aims to elucidate the effects of selected oligosaccharide fractions on the lipopolysaccharide (LPS) induced inflammatory response in equine peripheral blood mononuclear cells (PBMCs). We investigated three different products containing either galacto-oligosaccharides (GOS) alone, a combination of GOS with fructo-oligosaccharides (FOS), and a triple combination of GOS and FOS with acidic oligosaccharides (AOS), at different concentrations. These products have been used in an identical composition in various previously published in vivo experiments. As the selected oligosaccharide fractions were derived from natural products, the fractions contained defined amounts of mono- and disaccharides and minor amounts of endotoxin, which was taken into account in the design of the study and the analysis of data. Acquired data were analysed in a Bayesian hierarchical linear regression model, accounting for variation between horses.

RESULTS

Exposing cultured PBMCs to either GOS or GOS/FOS fractions resulted in a substantial dose-dependent increase of tumour necrosis factor-α (TNF-α) production in LPS challenged PBMCs. In contrast, incubation with GOS/FOS/AOS resulted in a dose-dependent reduction of both TNF-α and interleukin-10 production following LPS challenge. In addition, incubation with GOS/FOS/AOS significantly increased the apparent PBMC viability, indicating a protective or mitogenic effect. Furthermore, mono- and disaccharide control fractions significantly stimulated the inflammatory response in LPS challenged PBMCs as well, though to a lesser extent than GOS and GOS/FOS fractions.

CONCLUSIONS

We found distinct immunomodulating effects of the investigated standardised oligosaccharide fractions, which either stimulated or suppressed the LPS induced inflammatory response in PBMCs. Both scenarios require additional investigation, to elucidate underlying modulatory mechanisms, and to translate this knowledge into the clinical application of oligosaccharide supplements in foals and other neonates.