Social isolation and loneliness with risk of cardiometabolic multimorbidity: A prospective cohort study from UK Biobank.

The pandemic of the coronavirus disease 2019 resulted in an increased prevalence of social isolation and loneliness. Cox proportional hazards regression was used to test the association between social isolation/loneliness, multiple cardiometabolic diseases (CMDs) and cardiometabolic multimorbidity (CMM). In the multivariable adjusted models, compared with the least isolated, the most isolated had independently associated with CMD (HR 1.07, 95% CI 1.03 to 1.11) and CMM (HR 1.24, 95% CI 1.12 to 1.36) in stage I, and CMM in stage II (HR 1.14, 95% CI 1.05 to 1.23). Compared with those with the least loneliness, those who with most loneliness had about 20% increased risk of CMD and 29% increased risk of CMM in stage I. Those with the most loneliness were also significantly associated with increased CMM risk (HR 1.30, 95% CI 1.19 to 1.42) in stage II. This study revealed the associations of social isolation/loneliness with CMD and CMM.

Role of profilin-1 in vasculopathy induced by advanced glycation end products (AGEs).

AIMS: To construct a simple and feasible rat model to mimic diabetic vasculopathy by chronic injection of advanced glycation end products (AGEs) and further determine the role of profilin-1 in vasculopathy in AGE-injection rats. METHODS: Sprague-Dawley rats were injected with AGEs-BSA (25 mg/kg/day) for 0, 20, 30, 40, and 60 days by caudal vein. Then, the morphological changes in the aorta, heart, and kidney and the expression of profilin-1 were assessed. In cultured endothelial cells, shRNA profilin-1 was used to clarify the role of profilin-1 in AGEs-induced vascular endothelial lesions and inflammatory reactions. RESULTS: The aorta, heart, and kidney of the AGE-injection rats had obvious morphological changes. Also, the indicators of vascular remodeling in the aorta significantly increased, accompanied by the increased expression of profilin-1 in the aorta, heart, and kidney and polysaccharide content on the kidney basement membrane. In addition, the protein level of profilin-1 was markedly upregulated in the aorta of AGEs-injected rats and endothelial cells incubated with AGEs. shRNA profilin-1 markedly attenuated the upregulated expression of profilin-1, receptor for AGEs (RAGE), and NF-κB in endothelial cells incubated with AGEs, as well as reduced the high levels of ICAM-1, IL-8, TNF-α, ROS, and apoptosis induced by AGEs. CONCLUSIONS: Exogenous AGEs can mimic diabetic vasculopathy in vivo to some extent and increase profilin-1 expression in the target organs of diabetic complications. Blockade of profilin-1 attenuates vascular lesions and inflammatory reactions, suggesting its critical role in the metabolic memory mediated by AGEs.

Personalized antihypertensive treatment guided by pharmacogenomics in China.

Background: The implementation of genotyping for anti-hypertensive drugs in clinical practice remains a challenge. We conducted this study to analyze the distribution of polymorphisms of antihypertensive drug-related genes in Changsha County in China and compare the clinical effectiveness of genotype-guided and clinical experience-guided antihypertensive therapy in hypertensive individuals. Methods: A total of 9,933 essential hypertensive participants from Changsha County were consecutively enrolled in our study, and 7 genetic polymorphic loci (CYP2D6*10, ADRB1, CYP2C9*3, AGTR1, ACE, CYP3A5*3 and NPPA) were detected by a polymerase chain reaction (PCR)-fluorescence probe. From an available sample of 660 hypertensive participants, 495 cases were randomly identified by genotype-guided therapy and 165 cases by clinical experience-guided therapy. We performed 24-hour ambulatory blood pressure (BP) monitoring on each of these cases, pre- and post-intervention. Results: In the enrolled 9,933 cases, the mutation frequencies of CYP2C9*3, ADRB1(1165G>C), AGTR1(1166A>C), CYP2D6*10, ACE(I/D), CYP3A5*3 and NPPA(2238T>C) were 4.41%, 74.60%, 5.55%, 57.08%, 30.94%, 69.03% and 1.19%, respectively. In both genotype-guided and clinical experience-guided groups, the comparisons of intra-group pre-and post-treatments showed significant decreases in diastolic blood pressure (DBP) (P<0.01) and significant increases in the control rate of BP (47.1% vs. 38.6% and 37.5% vs. 33.9%, P<0.05) in response to adjusted antihypertensive agents. Correspondingly, the extent of the reduction of systolic blood pressure (SBP; 3.52±11.72 vs. 0.92±9.14 mmHg), the extent of the increase in the rate of BP control (8.5% vs. 3.6%) and the percentage rate of decrease of grades 2 and 3 hypertensive individuals were more significant in the genotype-guided group than that in the clinical experience-guided group (P<0.01). Conclusions: While prescribing anti-hypertensive drugs, appropriate dosage and type adjustments should be made according to the gene mutation frequency and individual circumstances. Pharmacogenomics-guided personalized treatment of hypertensive patients is likely to be a more effective strategy, especially in those with significantly elevated SBP.

Profilin-1 is involved in macroangiopathy induced by advanced glycation end products via vascular remodeling and inflammation.

BACKGROUND: The accumulation of advanced glycation end products (AGEs) have been implicated in the development and progression of diabetic vasculopathy. However, the role of profilin-1 as a multifunctional actin-binding protein in AGEs-induced atherosclerosis (AS) is largely unknown. AIM: To explore the potential role of profilin-1 in the pathogenesis of AS induced by AGEs, particularly in relation to the Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) signaling pathway. METHODS: Eighty-nine individuals undergoing coronary angiography were enrolled in the study. Plasma cytokine levels were detected using ELISA kits. Rat aortic vascular smooth muscle cells (RASMCs) were incubated with different compounds for different times. Cell proliferation was determined by performing the MTT assay and EdU staining. An AGEs-induced vascular remodeling model was established in rats and histological and immunohistochemical analyses were performed. The mRNA and protein levels were detected using real-time PCR and Western blot analysis, respectively. In vivo, shRNA transfection was performed to verify the role of profilin-1 in AGEs-induced proatherogenic mediator release and aortic remodeling. Statistical analyses were performed using SPSS 22.0 software. RESULTS: Compared with the control group, plasma levels of profilin-1 and receptor for AGEs (RAGE) were significantly increased in patients with coronary artery disease, especially in those complicated with diabetes mellitus (P < 0.01). The levels of profilin-1 were positively correlated with the levels of RAGE (P < 0.01); additionally, the levels of both molecules were positively associated with the degree of coronary artery stenosis (P < 0.01). In vivo, tail vein injections of AGEs induced the release of proatherogenic mediators, such as asymmetric dimethylarginine, intercellular adhesion molecule-1, and the N-terminus of procollagen III peptide, concomitant with apparent aortic morphological changes and significantly upregulated expression of the profilin-1 mRNA and protein in the thoracic aorta (P < 0.05 or P < 0.01). Downregulation of profilin-1 expression with an shRNA significantly attenuated AGEs-induced proatherogenic mediator release (P < 0.05) and aortic remodeling. In vitro, incubation of vascular smooth muscle cells (VSMCs) with AGEs significantly promoted cell proliferation and upregulated the expression of the profilin-1 mRNA and protein (P < 0.05). AGEs (200 µg/mL, 24 h) significantly upregulated the expression of the STAT3 mRNA and protein and JAK2 protein, which was blocked by a JAK2 inhibitor (T3042-1) and/or STAT3 inhibitor (T6308-1) (P < 0.05). In addition, pretreatment with T3042-1 or T6308-1 significantly inhibited AGEs-induced RASMC proliferation (P < 0.05). CONCLUSION: AGEs induce proatherogenic events such as VSMC proliferation, proatherogenic mediator release, and vascular remodeling, changes that can be attenuated by silencing profilin-1 expression. These results suggest a crucial role for profilin-1 in AGEs-induced vasculopathy.

Nucleolin promotes Ang II-induced phenotypic transformation of vascular smooth muscle cells by regulating EGF and PDGF-BB.

RNA-binding properties of nucleolin play a fundamental role in regulating cell growth and proliferation. We have previously shown that nucleolin plays an important regulatory role in the phenotypic transformation of vascular smooth muscle cells (VSMCs) induced by angiotensin II (Ang II). In the present study, we aimed to investigate the molecular mechanism of nucleolin-mediated phenotypic transformation of VSMCs induced by Ang II. Epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) inhibitors were used to observe the effect of Ang II on phenotypic transformation of VSMCs. The regulatory role of nucleolin in the phenotypic transformation of VSMCs was identified by nucleolin gene mutation, gene overexpression and RNA interference technology. Moreover, we elucidated the molecular mechanism underlying the regulatory effect of nucleolin on phenotypic transformation of VSMCs. EGF and PDGF-BB played an important role in the phenotypic transformation of VSMCs induced by Ang II. Nucleolin exerted a positive regulatory effect on the expression and secretion of EGF and PDGF-BB. In addition, nucleolin could bind to the 5' untranslated region (UTR) of EGF and PDGF-BB mRNA, and such binding up-regulated the stability and expression of EGF and PDGF-BB mRNA, promoting Ang II-induced phenotypic transformation of VSMCs.

Anti-Inflammatory Activity of Adenosine 5'-Trisphosphate in Lipopolysaccharide-Stimulated Human Umbilical Vein Endothelial Cells Through Negative Regulation of Toll-Like Receptor MyD88 Signaling.

Activation of TLR4-MyD88-NF-κB signaling by lipopolysaccharide (LPS) evokes a proinflammatory immune response, and plays a pivotal role in initiation and progression of atherosclerosis (AS). ATP (adenosine 5'-trisphosphate), a powerful extracellular signal transduction molecule, functions to regulate immune inflammatory responses depending on the type of P2 receptors and cell lines. In this study, we first performed RT-PCR to detect the mRNA expression of monocyte chemoattractant protein-1 (MCP-1), IL-8, and IL-1ß induced by different concentrations of LPS in human umbilical vein endothelial cells (HUVECs). Protein level of TLR4 signaling including TLR4, myeloid differentiation factor (MyD88), and CD14 induced by LPS (1 µg/mL) at different times (0, 10, 30, 60, 120 min) was analyzed by Western blot. Then, RT-PCR was performed to detect the effect of different concentrations of ATP on mRNA expression of IL-1ß and MCP-1 induced by LPS (1 µg/mL) and the TLR4 signaling pathway. Western blot was performed to detect the effect of low concentrations of ATP on phosphorylation of p65 induced by 1 µg/mL LPS. Finally, we used P2Y receptor blocker Suramin to verify whether the role of ATP on LPS-induced inflammatory cytokine expression was through P2Y receptors. The results showed that LPS upregulated the expression of MCP-1, IL-8, and IL-1ß in a dose-dependent manner accompanied by the activation of TLR4-MyD88 signaling in HUVECs. Only low concentration ATP (1, 10 µM) inhibited LPS-induced mRNA expression of IL-1ß and MCP-1. ATP at low concentrations also downregulated the mRNA expression of TLR4, CD14, and MyD88 and inhibited LPS-induced phosphorylation of p65. Furthermore, Suramin, a nonspecific P2Y receptor antagonist, did not attenuate the inhibition of ATP on LPS-induced IL-1ß and MCP-1 expression. Taking this together, low concentration ATP inhibited LPS-induced inflammation in HUVECs by negatively regulating TLR4-MyD88 signaling, and P2Y receptors were not involved in this process, which might provide new ideas for prevention and treatment of inflammatory diseases such as AS.

[STAT3 inhibitor Stattic induced IL-8 production and cell apotosis in THP-1 cells by activating ERK pathway].

Objective To observe the effect of selectively inhibiting STAT3 on the production of IL-8 and cell apoptosis of THP-1 cells by Stattic, and explore the underlying mechanism. Methods THP-1 cells were treated with different concentrations of Stattic ( 0, 1, 5, 10, 15, 20 µmol/L) for 0, 1, 3, 6, 12, 24 hours. Reverse transcription PCR or real-time PCR was performed to detect the mRNA expression of IL-8, IL-6, IL-1ß and tumor necrosis factor-α (TNF-α); ELISA was used to detect the protein expression of IL-8; flow cytometry was applied to evaluate the apoptosis of THP-1 cells; and Western blot analysis was performed to detect the phosphorylation of STAT3 and extracellular signal-regulated kinase (ERK). Reverse transcription PCR was used to test the effect of U0126 at different concentrations (0, 1, 5, 10 µmol/L) on the mRNA expression of IL-8 induced by Stattic in THP-1 cells. Results Stattic significantly up-regulated the mRNA and protein expression of IL-8 in THP-1 cells in a concentration range of 10~20 µmol/L, and induced cell apoptosis only at high concentration (15, 20 µmol/L). Treated with Stattic for 0, 1, 3, 6, 12, 24 hours, IL-8 mRNA was significantly up-regulated, and after 6 hours, the expression of IL-8 protein and apoptosis of THP-1 cells were up-regulated in a time-dependent manner. STAT3 phosphorylation was inhibited in a time- and dose-dependent manner by Stattic. ERK phosphorylation was induced by different concentrations of Stattic in a time-dependent manner. In addition, U0126, a selective inhibitor of ERK pathway, inhibited Stattic-induced IL-8 expression in a concentration-dependent manner. Conclusion Stattic, a selective STAT3 inhibitor, can induce the apoptosis and IL-8 production by activating ERK signaling pathway in THP-1 cells.

Nucleolin promotes Ang II­induced phenotypic transformation of vascular smooth muscle cells via interaction with tropoelastin mRNA.

The current study aimed to clarify the role of nucleolin in the phenotypic transformation of vascular smooth muscle cells (VSMCs) and to preliminarily explore its underlying mechanism. The spatial and temporal expression patterns of nucleolin, and the effects of angiotensin II (Ang II) on the expression of VSMC phenotypic transformation markers, α­smooth muscle­actin, calponin, smooth muscle protein 22α and osteopontin were investigated. The effects of nucleolin on VSMC phenotypic transformation and the expression of phenotypic transformation­associated genes, tropoelastin, epiregulin and fibroblast growth factor 2 (b­FGF), were determined. Protein­RNA co­immunoprecipitation was used to investigate the potential target genes regulated by the nucleolin in phenotypic transformation of VSMCs. Finally, the stability of tropoelastin mRNA and the effects of nucleolin on the expression of tropoelastin were assayed. The results revealed that Ang II significantly promoted the phenotypic transformation of VSMCs. The expression of nucleolin was gradually upregulated in VSMCs treated with Ang II at different concentrations for various durations. Ang II induced nucleolin translocation from the nucleus to cytoplasm. Additionally, Ang II significantly promoted the phenotypic transformation of VSMCs. Overexpression and silencing of nucleolin regulated the expressions of tropoelastin, epiregulin and b­FGF. There was an interaction between tropoelastin mRNA and nucleolin protein, promoting the stability of tropoelastin mRNA and enhancing the expression of tropoelastin at the protein level. Upregulation of nucleolin had an important role in Ang II­induced VSMC phenotypic transformation, and its underlying mechanism may be through interacting with tropoelastin mRNA, leading to its increased stability and protein expression. The findings provide a new perspective into the regulatory mechanism of VSMC phenotypic transformation.

Adenosine diphosphate-sensitive P2Y11 receptor inhibits endothelial cell proliferation by induction of cell cycle arrest in the S phase and induces the expression of inflammatory mediators.

Extracellular adenosine diphosphate (ADP) mediates a wide range of physiological effects as an extracellular signaling molecule, including platelet aggregation, vascular tone, cell proliferation, and apoptosis by interacting with plasma membrane P2 receptors. However, the effect of ADP on cell proliferation was contradictory. In this study, we found that ADP significantly inhibited cell proliferation of human umbilical vein endothelial cells at high concentrations (50 to 100 µM). Treatment with ADP did not induce cell apoptosis but instead induced cell cycle arrest in the S phase, which may be partly due to the downregulation of cyclin B1. The inhibition of cell proliferation was blocked by suramin, a nonspecific antagonist of the P2 receptors, and high concentrations of ADP significantly upregulated the messenger RNA (mRNA) and protein expression of P2Y11 in endothelial cells. Moreover, the downregulation of P2Y11 by RNA interference reversed the inhibition of cell proliferation. In addition, ADP (100 µM) can induce the formation of cytosolic autophagy in endothelial cells and a rapid phosphorylation of extracellular signal regulated kinase (ERK) 1/2, which is a canonical signal molecule downstream of P2Y receptors, accompanied by a mRNA expression of proinflammatory cytokines such as intercellular adhesion molecule 1 and vascular cell adhesion molecule 1. Taken together, our study excludes a mechanism for extracellular ADP impairing endothelial cells proliferation via P2Y11 receptor by downregulating cyclin B1 and arresting cell cycle at the S phase, besides, ADP induces cell autophagy and mRNA expression of inflammatory cytokines, whether it is mediated by Erk signaling pathways needs further studies to confirm.

[Effects of ATP on expression of inflammatory factors in endothelial progenitor cells induced by LPS and the mechanisms].

OBJECTIVE: To investigate the effects of adenosine triphosphate (ATP) on expression of inflammatory factors induced by lipopolysaccharide (LPS) in endothelial progenitor cells (EPCs), and to elucidate the possible mechanisms.
 Methods: Mononuclear cells were isolated from human umbilical cord blood by density gradient centrifugation, RT-PCR was performed to detect the expression of inflammatory factors induced by LPS (1 mg/mL) in EPCs, the effect of low concentration (5 µmol/L) of ATP on expression of IL-1ß, MCP-1 and ICAM-1, and the effect of different concentrations (5, 50 µmol/L) of ATP on the expression of Toll-like receptor (TLR) 4, myeloid differentiation primary response protein 88 (MyD88) and CD14. Western blot was performed to detect expression of TLR4 regulated proteins MyD88 and CD14 or to detect the low concentration (1, 5 µmol/L) of ATP on the expression of TLR4, MyD88 and CD14 and the NF-κB signaling pathway.
 Results: EPCs highly expressed TLR4, and its ligand LPS (1 mg/mL) significantly upregulated mRNA expression of IL-1ß, MCP-1 and ICAM-1 and protein expression of MyD88 and CD14 in a time-dependent manner (P<0.01), accompanied by activation of ERK and NF-κB signal pathway. ATP at low concentration (5 µmol/L) significantly inhibited LPS-induced mRNA expression of IL-1ß, MCP-1 and ICAM-1(P<0.05), downregulated the LPS-induced protein expression of TLR4, MyD88 and CD14 in EPCs (P<0.05), and suppressed LPS-induced activation of NF-κB signaling pathway (P<0.05).
 Conclusion: ATP at low concentration may suppress LPS-induced expression of inflammatory factors in EPCs through negative regulation of the TLR4 signaling pathway.

TNF-α-Induced NOD2 and RIP2 Contribute to the Up-Regulation of Cytokines Induced by MDP in Monocytic THP-1 Cells.

Nucleotide-binding oligomerization domain containing 2 (NOD2)-induced signal transduction and cytokine production is regulated by a number of factors. However, the feedback effect of the pro-inflammatory TNF-α on NOD2-induced inflammation is not fully understood. In this study, we found unexpectedly that TNF-α up-regulated NOD2 ligand MDP-induced production of the CXC chemokines, including CXCL1, 2, and 8, and the pro-inflammatory cytokines, including IL-1ß, IL-6, and TNF-α, in a dose-dependent manner at both mRNA and protein levels in monocytic THP-1 cells. Though TNF-α induced the up-regulation of ubiquitin-editing enzyme A20, an important negative regulator for Toll-like receptor- and NOD2-induced inflammatory responses, the over-expression of A20 by gene transfer did not reversed MDP-induced production of cytokines, suggested that A20 did not regulate the functions of NOD2 in THP-1 cells. Meanwhile, we found that TNF-α up-regulated NOD2 and its down-stream adaptor protein RIP2 at both mRNA and protein levels. MDP induced the activation of ERK, JNK, p38 and NF-κB, and TNF-α pre-treatment augmented this activation. The results from pharmacological inhibition assay showed that cytokine production was dependent on MAPK signaling. In addition, we found that the pre-treatment of THP-1 cells with MDP down-regulated the mRNA levels of cytokine induced by MDP re-treatment. MDP pre-treatment up-regulated NOD2, but down-regulated RIP2, and down-regulated NOD2 signal transduction induced by MDP re-stimulation. Taking together, these results suggested that TNF-α is a positive regulator for NOD2 functions via up-regulation of NOD2 and its signal adaptor RIP2, and TNF-α-induced A20 does not regulate MDP-induced inflammatory responses in THP-1 cells. J. Cell. Biochem. 119: 5072-5081, 2018. © 2017 Wiley Periodicals, Inc.

Thermally Reversible and Irreversible Phase Transition Behaviors in Poly(ethylene oxide)/Ionic Liquid Mixtures.

The irreversible and reversible phase transition behaviors during phase separation-recovery (heating-cooling) cycles for poly(ethylene oxide)/1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid (PEO/[EMIM][BF4 ]) mixtures with a lower critical solution temperature phase diagram are reported for the first time. The evident differential scanning calorimetry endothermic and exothermic peaks are observed during the heating-cooling scan cycles near the phase boundary, in which the large heat loss for samples below the critical composition (60 wt% PEO) and obvious downward shift of phase transition temperature for all the compositions between the first and second cycles are particularly attractive. After the first recovery process, a reversible behavior during the next cycles is expected. These interesting phenomena are further confirmed by optical microscopy and Fourier-transform infrared measurements. It is demonstrated that the disruption and partial recovery of the hydrogen bonds, combined with the conformational change of PEO chains, can contribute to this irreversible behavior as well as a conversion to reversible phase transition behavior.

[Association of Toll-like receptor 2 and 4 gene polymorphisms with risk of coronary atherosclerotic artery disease in Hunan Han population].

OBJECTIVE: To explore Toll-like receptor 2 (TLR2) and TLR4 polymorphism in Han people from Hunan region and its association with coronary atherosclerotic heart disease.
 Methods: Sanger sequence and statistical analysis were performed to identify the polymorphism of TLR2 and TLR4 genes in 347 unrelated Hunan Han subjects, including 180 healthy people (control group) and 167 patients with coronary atherosclerotic heart disease (coronary atherosclerotic heart disease group).
 Results: There was no significant difference in the genotype frequency and allelic frequency for TLR2 SNP2258G>A and TLR4 SNP896A>G between the 2 groups (P>0.05), while there was significant difference in the TLR4 SNP1196C>T between the 2 groups (P<0.05).
 Conclusion: TLR4 SNP1196C>T polymorphism is associated with coronary atherosclerotic heart disease in Chinese Han populationin in Hunan region.

Unusual phase separation and rheological behavior of poly(ethylene oxide)/ionic liquid mixtures with specific interactions.

The phase separation behavior of poly(ethylene oxide) (PEO) in ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) was investigated by rheological, optical microscopy, FT-IR and DSC measurements. It is demonstrated that specific interactions, particularly the hydrogen bonding between PEO and the ionic liquids as evidenced by FT-IR, in which a subtle but apparent absorption peak shift near the phase transition appears, account for the unusual low critical solution temperature (LCST) phase separation. Unlike the typical trend in which the storage modulus G' simply increases with temperature near the phase boundary for polymer blends without specific interaction, in our study, a novel "V-shaped" rheological response is observed, namely a dip in G' followed by an upturn, especially at low PEO concentration (<50 wt%). The magnitude of the "V" dip has heating rate and frequency dependences, while Tr (the phase transition temperature) is almost unchanged with heating rate and frequency. Upon increasing the alkyl chain length on the imidazolium ring from an ethyl to a butyl, the "V-shape" becomes more prominent and shifts to higher temperature, which is consistent with the results of FT-IR and DSC, evidently due to the stronger hydrogen bonding interaction between PEO and [BMIM][BF4] than [EMIM][BF4]. This unusual "V" dip might be tentatively ascribed to the coupling effects of the breaking of the "hydrogen bonding cage" formed between PEO chains and IL molecules and dissolution of the heterogeneous clusters as verified by FT-IR and TEM, respectively, and the following upturn is dominated by the interface formation upon phase separation.

MDP up-regulates the gene expression of type I interferons in human aortic endothelial cells.

Muramyldipeptide (MDP), the minimum essential structure responsible for the immuno-adjuvant activity of peptidoglycan, is recognized by intracellular nuclear-binding oligomerization domain 2 (NOD2). Here, we obtained evidence that the treatment of human aortic endothelial cells (HAECs) with MDP up-regulated the gene expression of type I interferons in a dose- and time-dependent manner. MDP also up-regulated the expression of the receptor NOD2, suggesting that MDP may induce a positive feedback response. The up-regulation of interferons was not dependent on the TNFa signaling, as HAECs did not express TNFa with the stimulation of MDP, and TNFa neutralizing antibody did not decrease the induction of IFNs induced by MDP. RT-PCR results showed that HAECs expressed the gene transcripts of interferon regulatory factor (IRF) 1, 2, 3, 9. The western blot results showed that MDP induced the phosphorylation of IRF3. These results suggested that MDP induced the up-regulation of gene transcript of interferons through the activation of IRF3 signaling pathway. Meanwhile, MDP induced the gene expression of pro-inflammatory cytokines, including IL-1ß, IL-8, and MCP-1. Taken together, these results suggested that HAECs may play roles in the anti-infection immune response and in the induction of innate immunity.

Extracellular nucleotide inhibits cell proliferation and negatively regulates Toll-like receptor 4 signalling in human progenitor endothelial cells.

Extracellular nucleotides mediate a wide range of physiological effects by interacting with plasma membrane P2 purinergic receptors. P2 receptors are expressed in certain kinds of stem cells, and function to induce cytokine expression and to modulate cell proliferation. We have analysed the expression and the function of P2 receptors in human umbilical cord blood-derived EPCs (endothelial progenitor cells). EPCs expressed P2X4,6,7 and P2Y2,4,11,13,14 receptors and extracellular ATP inhibited EPCs proliferation. As in a previous study, EPCs expressed functional TLR4 (Toll-like receptor 4) and activation of TLR4 by LPS (lipopolysaccharide) evoked a pro-inflammatory immune response. When human EPCs were stimulated with LPS and nucleotides, ATP or UTP inhibited the expression of pro-inflammatory cytokines including MCP-1 (monocyte chemoattractant protein-1), IFNα (interferon α), TNFα (tumour necrosis factor α) and adhesion molecule VCAM-1 (vascular cell adhesion molecule 1) induced by LPS. ATP and UTP also down-regulated the gene expression of TLR4, CD14 and MyD88 (myeloid differentiation factor 88), a TLR adaptor molecule, and protein expression of CD14 and MyD88. Moreover, the phosphorylation of NF-κB (nuclear factor κB) p65 induced by TLR4 activation was inhibited partly by ATP or UTP at concentrations of 1-5 µM. These results suggest that extracellular nucleotides negatively regulate EPCs proliferation and TLR4 signalling.

The effect of endothelial progenitor cells on angiotensin II-induced proliferation of cultured rat vascular smooth muscle cells.

Previous studies have demonstrated that endothelial progenitor cells (EPCs) could delay the progress of vascular remodeling in blood vessel-proliferating diseases. The proliferation of vascular smooth muscle cells (VSMCs) is a pivotal factor in cardiovascular diseases. In this study, we investigated whether EPCs could inhibit the Angiotensin II (Ang II)-induced proliferation of VSMCs. The effect of early EPC-conditioned medium (E-EPC-CM), late EPCs-CM (L-EPC-CM), and HUVEC-CM on Ang II-induced proliferation of VSMCs was assessed by BrdU incorporation, total protein content, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, and flow cytometry. Reverse transcriptase-polymerase chain reaction and Western blot were performed to analyze the effect of different CMs on Ang II-induced phosphorylations of ERK, JNK, p38, and NF-κB subunit p65 and the expressions of c-myc and c-fos. E-EPC-CM, L-EPC-CM, and HUVEC-CM significantly inhibited the Ang II-induced DNA synthesis, total protein expression, cell survival, and cell cycle progress of VSMCs. Furthermore, E-EPC-CM significantly inhibited the Ang II-induced phosphorylation of ERK, JNK, p38, and p65 (nuclear translocation of p65) and the expressions of c-myc and c-fos. Taken together, these data suggested that EPCs may delay the progress of vascular remodeling in blood vessel-proliferating diseases by inhibiting Ang II-induced proliferation of VSMCs through inactivating MAPKs and NF-κB signaling pathways and by reducing the expressions of c-myc and c-fos.

The functional expression of TLR3 in EPCs impairs cell proliferation by induction of cell apoptosis and cell cycle progress inhibition.

Toll-like receptor 3 (TLR3), a member of the TLR family that recognizes double-stranded RNA (dsRNA), plays an important role in antiviral immunity. TLR3 is widely expressed in various cells and the activation of TLR3 induces cell apoptosis in some cells. However, the effect of TLR3 on cell proliferation in endothelial progenitor cells (EPCs) is unclear. In this study, we found that EPCs expressed high levels of TLR1, 3, 4, and 6 and low levels of TLR2, 5, 7, 8, and 10. The treatment of EPCs with TLR3 agonist Poly I:C up-regulated the expression of cytokines IL-1ß, IL-6, IL-8, TNF-α, IFN-α, and IFN-ß, indicating that EPCs expressed functional TLR3. Moreover, Poly I:C treatment induced cell cycle progress inhibition and cell apoptosis, leading to the inhibition of cell proliferation. Further studies indicated that IL-1ß was involved in TLR3-induced cell proliferation inhibition, as IL-1ß inhibited cell proliferation in a dose-dependent manner, and the IL-1ß receptor type I (IL-1R1)-neutralizing antibody ameliorated Poly I:C-induced cell proliferation inhibition. Taken together, these results suggest that Poly I:C impairs cell proliferation by inducing cell cycle progress inhibition and cell apoptosis via TLR3 in EPCs.

Calcitonin gene-related peptide released from endothelial progenitor cells inhibits the proliferation of rat vascular smooth muscle cells induced by angiotensin II.

We have recently demonstrated that endothelial progenitor cells (EPCs) inhibit AngII-induced proliferation of vascular smooth muscle cells (VSMCs) by inactivating MAPKs and NF-κB signaling pathway and reducing expression of oncogene c-myc and c-fos. The inhibitory effect of EPCs on VSMCs is associated with paracrine mechanism. However, the potential mechanism of EPCs on the regulation of AngII-induced proliferation of VSMCs was unknown. Calcitonin gene-related peptide (CGRP) could inhibit AngII-induced proliferation and transformation of VSMCs. However, it has not been known whether CGRP released from EPCs is a potential regulator in regulation of AngII-induced proliferation of VSMCs. Early endothelial progenitor cell-conditioned medium(E-EPC-CM) was pre-incubated with functional blocking antibodies against CGRP for 1 h or VSMCs was preteated with CGRP(837)(CGRP receptor antagonist) for 1 h before VSMCs were pretreated with CM for 30 min. DNA synthesis ability, total protein levels, cell survival, signal transduction, and expressions of c-myc and c-fos of VSMCs induced by AngII (10(-6)mol/l) were detected to assess the role of CGRP in AngII-induced proliferation of VSMCs. E-EPC-CM could significantly inhibit AngII-induced DNA synthesis ability, total protein levels, cell survival, phosphorylation of ERK, JNK, p38, p65, and expressions of c-myc and c-fos compared with the control group(P < 0.05). However, Pretreatment with anti-CGRP antibody and CGRP(837) could significantly weaken the inhibitory effect of E-EPC-CM on proliferation of VSMCs induced by AngII (P < 0.05). EPCs exert anti-proliferative effects on VSMCs mediated by the release of CGRP.

P2Y11 impairs cell proliferation by induction of cell cycle arrest and sensitizes endothelial cells to cisplatin-induced cell death.

Extracellular ATP mediates a wide range of physiological effects, including cell proliferation, differentiation, maturation, and migration. However, the effect of ATP on cell proliferation has been contradictory, and the mechanism is not fully understood. In the current study, we found that extracellular ATP significantly inhibited the proliferation of human umbilical vein endothelial cells (HUVECs) and human aortic endothelial cells (HAECs). Treatment with ATP did not induce cell apoptosis but instead induced cell cycle arrest in S phase. ATP induced the phosphorylation of ERK1/2, but the ERK inhibitors, U0126 and PD9809, did not regulate the inhibition of cell proliferation induced by ATP. However, ATP-induced inhibition of cell proliferation was blocked by suramin, a nonspecific antagonist of the P2Y receptors, and endothelial cells expressed P2Y11, a P2Y receptor that specifically binds ATP. Moreover, the down-regulation of P2Y11 by RNA interference not only reversed the inhibition of cell proliferation but also ameliorated cell cycle arrest in S phase. In addition, P2Y11 sensitized endothelial cells to cisplatin-induced cell death by down-regulation of the expression of Bcl-2. Taken together, these results suggest that extracellular ATP impairs cell proliferation by triggering signaling to induce cell cycle arrest and sensitizes cell to death via P2Y11 in endothelial cells.