[Short-chain fatty acid butyrate acid attenuates atherosclerotic plaque formation in apolipoprotein E-knockout mice and the underlying mechanism].

This study was designed to evaluate the role of short-chain fatty acid butyrate acid on intestinal morphology and function, and atherosclerotic plaque formation in apolipoprotein E-knockout (ApoE-/-) mice. ApoE-/- mice on high-fat, high-cholesterol diet were treated with butyrate acid (200 mmol/L) or NaCl (control) in the drinking water for 12 weeks, followed by histological evaluations of atherosclerotic lesion in aorta. Real-time PCR analysis and ELISA were used to measure the expression levels of proinflammatory cytokines. Butyrate acid significantly attenuated high-fat, high-cholesterol diet-induced atherosclerotic plaque formation in ApoE-/- mice. Butyrate acid prevented high-fat, high-cholesterol diet-induced inflammation in both the aorta and the circulation, as evidenced by reduced expression of proinflammatory cytokines. These changes were accompanied by a marked attenuation in metabolic endotoxemia lipopolysaccharide (LPS). Butyrate acid induced intestinal expression of the tight junction proteins (Occludin and zona occuldens protein-1), thereby preventing the gut permeability. Butyrate acid dose-dependently upregulated the expression of the tight junction proteins in Caco-2 cells in GPR41-dependent manner. In conclusion, butyrate acid attenuates atherosclerotic lesions by ameliorating metabolic endotoxemia-induced inflammation through restoration of the gut barrier.

[AMP-activated protein kinase activation regulates adhesion of monocytes to vascular endothelial cells and the underlying mechanism].

The present study was aimed to explore the effect of AMP-activated protein kinase (AMPK) on monocyte adhesion to vascular endothelial cells and underlying molecular mechanism. Tumor necrosis factor α (TNFα)-activated human aortic endothelial cells (HAECs) were treated with different concentrations of AMPK agonist 5-Aminoimidazole-4-carboxamide-1-ß-D-ribonucleotide (AICAR) or AMPK inhibitor compound C. And other HAECs were overexpressed with constitutive active or dominant negative AMPK protein and then treated with TNFα. The rates of monocytes adhering to endothelial cells were detected by fluorescent staining. Intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) mRNA levels and protein secretions were detected by quantitative PCR and ELISA, respectively. Acetylation of NF-κB p65 at lysine 221 site was assessed by Western blot. NF-κB p65 DNA binding activity was analyzed by an ELISA-based method. By using small interfering RNA based strategy, p300 expression in HAECs was down-regulated and then cells were incubated with TNFα. NF-κB p65 DNA binding activity, ICAM-1 and VCAM-1 expressions and adhesion rates were detected, respectively. The activity of p300 was also detected by ELISA. The results showed that AICAR treatment significantly reduced monocyte-endothelial adhesion rate, as well as ICAM-1 and VCAM-1 mRNA levels and protein secretions, in TNFα-activated HAECs. Moreover, transfection of constitutive active AMPKα but not dominant negative AMPKα strongly diminished TNFα-induced upregulation of ICAM-1 and VCAM-1 mRNA expressions and secretions, as well as monocyte-endothelial adhesion. Furthermore, AMPK activation decreased TNFα-mediated acetylation of NF-κB p65 at Lys221 site and reduced NF-κB p65 DNA binding activity. Silencing p300 by siRNA significantly abolished the effect of TNFα- induced adhesion molecules expression and monocyte-endothelial adhesion. Blocking AMPK activation by compound C almost completely reversed the effect of AICAR exerted on HAECs. These results suggest AMPK activation suppresses monocyte-endothelial adhesion, and the underlying mechanism is relevant to the inhibition of p300 activity and NF-κB p65 transcriptional activity.

A novel controllable hydrogen sulfide-releasing molecule protects human skin keratinocytes against methylglyoxal-induced injury and dysfunction.

BACKGROUND/AIM: Delayed wound healing is a common skin complication of diabetes, which is associated with keratinocyte injury and dysfunction. Levels of methylglyoxal (MGO), an α-dicarbonyl compound, are elevated in diabetic skin tissue and plasma, while levels of hydrogen sulfide (H2S), a critical gaseous signaling molecule, are reduced. Interestingly, the gas has shown dermal protection in our previous study. To date, there is no evidence demonstrating whether MGO affects keratinocyte viability and function or H2S donation abolishes these effects and improves MGO-related impairment of wound healing. The current study was conducted to examine the effects of MGO on the injury and function in human skin keratinocytes and then to evaluate the protective action of a novel H2S-releasing molecule. METHODS: An N-mercapto-based H2S donor (NSHD)-1 was synthesized and its ability to release H2S was observed in cell medium and cells, respectively. HaCaT cells, a cell line of human skin keratinocyte, were exposed to MGO to establish an in vitro diabetic wound healing model. NSHD-1 was added to the cells before MGO exposure and the improvement of cell function was observed in respect of cellular viability, apoptosis, oxidative stress, mitochondrial membrane potential (MMP) and behavioral function. RESULTS: Treatment with MGO decreased cell viability, induced cellular apoptosis, increased intracellular reactive oxygen species (ROS) content and depressed MMP in HaCaT cells. The treatment also damaged cell behavioral function, characterized by decreased cellular adhesion and migration. The synthesized H2S-releasing molecule, NSHD-1, was able to increase H2S levels in both cell medium and cells. Importantly, pretreatment with NSHD-1 inhibited MGO-induced decreases in cell viability and MMP, increases in apoptosis and ROS accumulation in HaCaT cells. The pretreatment was also able to improve adhesion and migration function. CONCLUSION: These results demonstrate that the novel synthesized H2S donor is able to protect human skin keratinocytes against MGO-induced injury and behavior dysfunction. We believe that more reasonable H2S-releasing molecules will bring relief to patients suffering from delayed wound healing in diabetes mellitus in the future.

Intracellular signaling molecules involved in vasoactive intestinal peptide-mediated wound healing in human bronchial epithelial cells.

Vasoactive intestinal peptide (VIP), a non-adrenergic, non-cholinergic neuromediator, plays an important role in maintaining the bronchial tone of the airway and has anti-inflammatory properties. Recently, we reported that VIP enhances wound repair in human bronchial epithelial cells (HBEC). In the present study, we have identified the intracellular signaling molecules that are involved in VIP-mediated wound healing in HBEC. The effects of VIP on wound repair of HBEC were partially blocked by H-7 (a protein kinase C (PKC) inhibitor), W-7 (a calmodulin inhibitor), H-89 (a protein kinase A (PKA) inhibitor), and PD98059 (a specific extracellular signal-regulated kinase (ERK) inhibitor). VIP-induced chemotactic migration was inhibited in the presence of W-7, H-89, PD98059 or H-7. H-7, W-7, and H-89 were also found to decrease VIP-induced expression of Ki67 as well as the proliferation index in HBEC. Furthermore, H-7, W-7, H-89, and PD98059 inhibited the expression of E-cd protein and mRNA induced by VIP. These results suggest that intracellular signaling molecules such as PKA, PKC, ERK, and calmodulin play important role in VIP-mediated wound healing of HBEC.

Vasoactive intestinal peptide enhances wound healing and proliferation of human bronchial epithelial cells.

In the present study, we investigated the effects of vasoactive intestinal peptide (VIP) on wound healing of bronchial epithelium. Wound healing of the mechanical damaged human bronchial epithelial cells (HBEC) was observed in the absence or presence of VIP. Effects of VIP on chemotactic migration, cell proliferation of HBEC were also tested. HBEC chemotaxis was assessed by the blind well chamber technique, the cell cycle was determined by flow cytometry, and cell proliferation was determined by measuring the expression of proliferating cell nuclear antigen Ki67. Effects of VIP on epithelial E-cadherins protein and mRNA were also measured by immunohistochemistry and RT-PCR. The results showed that VIP accelerated the recovery of wound area of HBEC. VIP increased the migration and proliferation of HBEC, and these effects were blocked by a VPAC1 receptor antagonist. VIP also increased the expression of E-cadherin mRNA and protein in HBEC, suggesting that protective effects of VIP on wound healing may be related to its ability to increase the expression of E-cadherin. In conclusion, VIP has protective effects against human bronchial epithelial cell damage, and the beneficial effects of VIP might be mediated, at least in part, by VPAC1, and associated with increased expression of E-cadherin.

[Effects of vasoactive intestinal peptide on LPS-induced MMP-9 expression by alveolar macrophages in rats].

OBJECTIVE: To explore the role of vasoactive intestinal peptide (VIP) on LPS-induced MMP-9 expression by alveolar macrophages (AM) in rats. METHODS: LPS-induced cultured Wistar rats AMs were treated with different concentrations of VIP (10(-10) to approximately 10(-6) mol/L) for 24 h. AMs and the supernatant were collected to measure the MMP-9 expression and activity by RT-PCR and gelatin zymography, respectively. Results The MMP-9 activity and expression of LPS-induced AMs were significantly higher than those in the control group (P < 0.01). VIP (10(-9) to approximately 10(-6) mol/L) down-regulated LPS-induced MMP-9 activity and its expression. The effects were diminished by H-7 and W-7, an antagonist of protein kinase C (PKC) and calmodulin (CaM) (P < 0.01). CONCLUSION: VIP can decrease LPS-induced MMP-9 activity and its expression, which may be related to protein kinase C and calmodulin pathway. VIP may have protective roles in the lung injury.

[Effects of CGRP on the E-cadherin expression in human bronchial epithelial cells].

OBJECTIVE: To discuss the effect of calcitonin gene-related peptides (CGRP) on epithelial cadherin (E-cd) expression in human bronchial epithelial cells (HBECs) in vitro. METHODS: The effect of CGRP on E-cd protein and mRNA expression in both normal and O3-challenged HBECs were determined by immunocytochemistry and RT-PCR. The signal transduction pathways of CGRP were observed by using protein kinase C(PKC) inhibitor (H-7), calmodulin(CaM) inhibitor (W-7) and PKA inhibitor (H-89). RESULTS: CGRP increased E-cd mRNA and protein expressions of normal and O3-challenged HBECs in a dose-dependent manner. CGRP had no effect on cytoplasm E-cd expression. Pre-treatment with H-89, H-7 and W-7, the up-regulatory effect of CGRP on E-cd expression was partly abolished. CONCLUSION: CGRP increased in cytomembrane E-cd expression of normal and O3-challenged HBECs in a dose-dependent manner. E-cd expression on HBECs was strengthened by CGRP via PKA, PKC and CaM pathways.

[Effects of CGRP on LPS-induced MMP-9 secretion by alveolar macrophages].

AIM: To explore the effects of calcitonin-gene-related peptide (CGRP) on LPS-induced MMP-9 secretion by alveolar macrophages (AM) in vitro. METHODS: The supernatant of LPS-induced Wistar rat AM from different intervention groups were collected to measure the activity by gelatin zymography. RESULTS: (Only secreting a small amount of MMP-9 with unstimulated AM, LPS stimulated MMP-9 production in a concentration-dependent manner (p < 0.01). (2) The activity of MMP-9 in CGRP intervention groups at different levels were significantly lower than those in non-intervention group (p < 0.01). (3) The inhibiting effects of CGRP were diminished by H-7 and W-7, an antagonist of protein kinase C (PKC) and calmodulin (CaM) (p < 0.05). CONCLUSION: These data suggested that CGRP involved in the MMP-9 secretion by AM, partly, via PKC and CaM pathway.