GEF-H1/RhoA signalling pathway mediates lipopolysaccharide-induced intercellular adhesion molecular-1 expression in endothelial cells via activation of p38 and NF-κB

The Roles of RhoA/ROCK/NF-κB Pathway in Microglia Polarization Following Ischemic Stroke

Ischemic stroke is the leading cause of death and disability worldwide. Nevertheless, there still lacks the effective therapies for ischemic stroke. Microglia are resident macrophages of the central nervous system (CNS) and can initiate immune responses and monitor the microenvironment. Microglia are activated and polarize into proinflammatory or anti‑inflammatory phenotype in response to various brain injuries, including ischemic stroke. Proinflammatory microglia could generate immunomodulatory mediators, containing cytokines and chemokines, these mediators are closely associated with secondary brain damage following ischemic stroke. On the contrary, anti-inflammatory microglia facilitate recovery following stroke. Regulating the activation and the function of microglia is crucial in exploring the novel treatments for ischemic stroke patients. Accumulating studies have revealed that RhoA/ROCK pathway and NF-κB are famous modulators in the process of microglia activation and polarization. Inhibiting these key modulators can promote the polarization of microglia to anti-inflammatory phenotype. In this review, we aimed to provide a comprehensive overview on the role of RhoA/ROCK pathway and NF-κB in the microglia activation and polarization, reveal the relationship between RhoA/ROCK pathway and NF-κB in the pathological process of ischemic stroke. In addition, we likewise discussed the drug modulators targeting microglia polarization.

The role of RhoA/ROCK pathway in the ischemic stroke-induced neuroinflammation

It is widely known that ischemic stroke is the prominent cause of death and disability. To date, neuroinflammation following ischemic stroke represents a complex event, which is an essential process and affects the prognosis of both experimental stroke animals and stroke patients. Intense neuroinflammation occurring during the acute phase of stroke contributes to neuronal injury, BBB breakdown, and worse neurological outcomes. Inhibition of neuroinflammation may be a promising target in the development of new therapeutic strategies. RhoA is a small GTPase protein that activates a downstream effector, ROCK. The up-regulation of RhoA/ROCK pathway possesses important roles in promoting the neuroinflammation and mediating brain injury. In addition, nuclear factor-kappa B (NF-κB) is another vital regulator of ischemic stroke-induced neuroinflammation through regulating the functions of microglial cells and astrocytes. After stroke onset, the microglial cells and astrocytes are activated and undergo the morphological and functional changes, thereby deeply participate in a complicated neuroinflammation cascade. In this review, we focused on the relationship among RhoA/ROCK pathway, NF-κB and glial cells in the neuroinflammation following ischemic stroke to reveal new strategies for preventing the intense neuroinflammation.

GEF-H1/RhoA signaling pathway mediates pro-inflammatory effects of NF-κB on CD40L-induced pulmonary endothelial cells

One of the key targets of the inflammatory response in acute lung injury (ALI) is the human pulmonary micro-vascular endothelial cells (HPMVECs). Owing to its role in the activation of endothelial cells (ECs), CD40L figures prominently in the pathogenesis of ALI. Increasing evidences have showed that CD40L mediates inflammatory effects on ECs, at least in part, by triggering NF-κB-dependent gene expression. However, the mechanisms of such signal transmission remain unknown. In this study, we found that CD40L stimulated the transactivation of NF-κB and expression of its downstream cytokines in a p38 MAPK-dependent mechanism in HPMVECs. In addition, CD40L-mediated inflammatory effects might be correlated with the activation of the IKK/IκB/NF-κB pathway and nuclear translocation of NF-κB, being accompanied by dynamic cytoskeletal changes. GEF-H1/RhoA signaling is best known for its role in regulating cytoskeletal rearrangements. An interesting finding was that CD40L induced the activation of p38 and IKK/IκB, and the subsequent transactivation of NF-κB via GEF-H1/RhoA signaling. The critical role of GEF-H1/RhoA in CD40L-induced inflammatory responses in the lung was further confirmed in GEF-H1 and RhoA knockout mouse models, both of which were established by adeno-associated virus (AAV)-mediated delivery of sgRNAs into mice with EC-specific Cas9 expression. These results taken together suggested that p38 and IKK/IκB-mediated signaling pathways, both of which lied downstream of GEF-H1/RhoA, may coordinately regulate the transactivation of NF-κB in CD40L-activated HPMVECs. These findings may help to determine key pharmacological targets of intervention for CD40L-activated inflammatory effects associated with ALI.

Statins change the cytokine profile in Trypanosoma cruzi-infected U937 macrophages and murine cardiac tissue through Rho-associated kinases inhibition

Introduction

Chronic Chagasic cardiomyopathy (CCC), caused by the protozoan Trypanosoma cruzi, is the most severe manifestation of Chagas disease.CCC is characterized by cardiac inflammation and fibrosis caused by a persistent inflammatory response. Following infection, macrophages secrete inflammatory mediators such as IL-1β, IL-6, and TNF-α to control parasitemia. Although this response contains parasite infection, it causes damage to the heart tissue. Thus, the use of immunomodulators is a rational alternative to CCC. Rho-associated kinase (ROCK) 1 and 2 are RhoA-activated serine/threonine kinases that regulate the actomyosin cytoskeleton. Both ROCKs have been implicated in the polarization of macrophages towards an M1 (pro-inflammatory) phenotype. Statins are FDA-approved lipid-lowering drugs that reduce RhoA signaling by inhibiting geranylgeranyl pyrophosphate (GGPP) synthesis. This work aims to identify the effect of statins on U937 macrophage polarization and cardiac tissue inflammation and its relationship with ROCK activity during T. cruzi infection.

Methods

PMA-induced, wild-type, GFP-, CA-ROCK1- and CA-ROCK2-expressing U937 macrophages were incubated with atorvastatin, or the inhibitors Y-27632, JSH-23, TAK-242, or C3 exoenzyme incubated with or without T. cruzi trypomastigotes for 30 min to evaluate the activity of ROCK and the M1 and M2 cytokine expression and secretion profiling. Also, ROCK activity was determined in T. cruzi-infected, BALB/c mice hearts.

Results

In this study, we demonstrate for the first time in macrophages that incubation with T. cruzi leads to ROCK activation via the TLR4 pathway, which triggers NF-κB activation. Inhibition of ROCKs by Y-27632 prevents NF-κB activation and the expression and secretion of M1 markers, as does treatment with atorvastatin. Furthermore, we show that the effect of atorvastatin on the NF-kB pathway and cytokine secretion is mediated by ROCK. Finally, statin treatment decreased ROCK activation and expression, and the pro-inflammatory cytokine production, promoting anti-inflammatory cytokine expression in chronic chagasic mice hearts.

Conclusion

These results suggest that the statin modulation of the inflammatory response due to ROCK inhibition is a potential pharmacological strategy to prevent cardiac inflammation in CCC.

Cardioprotective Effects of Vitex negundo: A Review of Bioactive Extracts and Compounds

There has been accumulating interest in the application of medicinal plants as alternative medicine to treat various diseases and/or to develop modern medicines. Vitex negundo is one of such medicinal plants that has been of interest to many researchers and has been of use in traditional medicine. V. negundo is found in Sri Lanka, Madagascar, Malaysia, India, China, The Philippines and East Africa. Therapeutic properties of V. negundo have previously been reviewed. Different parts, preparations and bioactive components of V. negundo possess potential protective and therapeutic effects against cardiovascular disease and related conditions as demonstrated in previous studies. We review the present state of scientific knowledge on the potential use of V. negundo and some of its bioactive components in protecting against cardiovascular diseases and related pathologies. Previous studies in animal and non-animal experimental models, although limited in number and vary in design, seem to support the cardioprotective effect of V. negundo and some of its active components. However, there is need for further preclinical and clinical studies to validate the use of V. negundo and its active constituents in protection and treatment of cardiovascular diseases. Additionally, since only a few V. negundo compounds have been evaluated, specific cardioprotective effects or mechanisms and possible side effects of other V. negundo compounds need to be extensively evaluated.

ICAM-1 targeted thermal-sensitive micelles loaded with tofacitinib for enhanced treatment of rheumatoid arthritis via microwave assistance

Rheumatoid arthritis (RA) is an immune-mediated inflammatory disease without effective treatment. Tofacitinib (TOF) is a JAK inhibitor that can be used for RA therapy, but it still faces the problems of nonspecific distribution and relatively low therapeutic effect. Herein, ICAM-1-modified TOF-loaded P(AN-co-AAm)-PEG micelles (AI-TM) were developed, which can result in an enhanced RA therapy when combining with microwave hyperthermia (MH). It was found that AI-TM could rapidly release the encapsulated TOF under a thermal condition of >43 °C, which was due to the fact that the polymeric micelles has an upper critical solution temperature (UCST) of 43 °C. AI-TM could specifically distribute into the inflamed joints of RA mice, which is associated with the high affinity between anti-ICAM-1 and overexpressed ICAM-1 receptors. Moreover, the combination of AI-TM and MH could result in a remarkably enhanced anti-rheumatic activity, which was related to the RA-targeted ability of AI-TM, the rapid TOF release under MH, and the combined effect between TOF and MH treatment. Our study definitely provides a novel strategy for effective treatment of RA.

Unlocking the Untapped Potential of Endothelial Kinase and Phosphatase Involvement in Sepsis for Drug Treatment Design

Sepsis is a devastating clinical condition that can lead to multiple organ failure and death. Despite advancements in our understanding of molecular mechanisms underlying sepsis and sepsis-associated multiple organ failure, no effective therapeutic treatment to directly counteract it has yet been established. The endothelium is considered to play an important role in sepsis. This review highlights a number of signal transduction pathways involved in endothelial inflammatory activation and dysregulated endothelial barrier function in response to sepsis conditions. Within these pathways – NF-κB, Rac1/RhoA GTPases, AP-1, APC/S1P, Angpt/Tie2, and VEGF/VEGFR2 – we focus on the role of kinases and phosphatases as potential druggable targets for therapeutic intervention. Animal studies and clinical trials that have been conducted for this purpose are discussed, highlighting reasons why they might not have resulted in the expected outcomes, and which lessons can be learned from this. Lastly, opportunities and challenges that sepsis and sepsis-associated multiple organ failure research are currently facing are presented, including recommendations on improved experimental design to increase the translational power of preclinical research to the clinic.

The mitochondrial redistribution of eNOS is involved in lipopolysaccharide induced inflammasome activation during acute lung injury

Acute lung injury (ALI) is a devastating clinical syndrome with no effective therapies. Inflammasome activation has been reported to play a critical role in the initiation and progression of ALI. The molecular mechanisms involved in regulating the activation of inflammasome in ALI remains unresolved, although increases in mitochondrial derived reactive oxygen species (mito-ROS) are involved. Our previous work has shown that the mitochondrial redistribution of uncoupled eNOS impairs mitochondrial bioenergetics and increases mito-ROS generation. Thus, the focus of our study was to determine if lipopolysaccharide (LPS)-mediated inflammasome activation involves the mitochondrial redistribution of uncoupled eNOS. Our data show that the increase in mito-ROS involved in LPS-mediated inflammasome activation is associated with the disruption of mitochondrial bioenergetics in human lung microvascular endothelial cells (HLMVEC) and the mitochondrial redistribution of eNOS. These effects are dependent on RhoA-ROCK signaling and are mediated via increased phosphorylation of eNOS at Threonine (T)-495. A derivative of the mitochondrial targeted Szeto-Schiller peptide (SSP) attached to the antioxidant Tiron (T-SSP), significantly attenuated LPS-mediated mito-ROS generation and inflammasome activation in HLMVEC. Further, T-SSP attenuated mitochondrial superoxide production in a mouse model of sepsis induced ALI. This in turn significantly reduced the inflammatory response and attenuated lung injury. Thus, our findings show that the mitochondrial redistribution of uncoupled eNOS is intimately involved in the activation of the inflammatory response in ALI and implicate attenuating mito-ROS as a therapeutic strategy in humans.

Genistein-3'-sodium sulphonate protects against lipopolysaccharide-induced lung vascular endothelial cell apoptosis and acute lung injury via BCL-2 signalling

Under septic conditions, Lipopolysaccharide (LPS)‐induced apoptosis of lung vascular endothelial cells (ECs) triggers and aggravates acute lung injury (ALI), which so far has no effective therapeutic options. Genistein‐3′‐sodium sulphonate (GSS) is a derivative of native soy isoflavone, which has neuro‐protective effects through its anti‐apoptotic property. However, whether GSS protects against sepsis‐induced lung vascular endothelial cell apoptosis and ALI has not been determined. In this study, we found that LPS‐induced Myd88/NF‐κB/BCL‐2 signalling pathway activation and subsequent EC apoptosis were effectively down‐regulated by GSS in vitro. Furthermore, GSS not only reversed the sepsis‐induced BCL‐2 changes in expression in mouse lungs but also blocked sepsis‐associated lung vascular barrier disruption and ALI in vivo. Taken together, our results demonstrated that GSS might be a promising candidate for sepsis‐induced ALI via its regulating effects on Myd88/NF‐κB/BCL‐2 signalling in lung ECs.

Recent Advances in Studies of Molecular Hydrogen against Sepsis

Sepsis is a syndrome comprised of a series of life-threatening organ dysfunctions caused by a maladjusted body response to infection with no effective treatment. Molecular hydrogen is a new type of antioxidant with strong free radical scavenging ability, which has been demonstrated to be effective for treating various diseases, such as infection, trauma, poisoning, organ ischemia-reperfusion, metabolic diseases, and tumors. Molecular hydrogen exerts multiple biological effects involving anti-inflammation, anti-oxidation, anti-apoptosis, anti-shock, and autophagy regulation, which may attenuate the organ and barrier damage caused by sepsis. However, the underlying molecular mechanisms remain elusive, but are likely related to the signaling pathways involved. This review focuses on the research progress and potential mechanisms of molecular hydrogen against sepsis to provide a theoretical basis for clinical treatment.

The Ocular Hypotensive Efficacy of Topical Fasudil, a Rho-Associated Protein Kinase Inhibitor, in Patients With End-Stage Glaucoma

To investigate the effects of topical administration of a selective Rho-associated kinase (ROCK) inhibitor, fasudil 0.5% and 1.2% in glaucomatous patients. In this interventional case series study, 4 eyes of 4 patients with unilateral end-stage primary open-angle glaucoma and no light perception vision were assigned to receive topical fasudil 0.5% (in 3 eyes) or 1.2% (in 1 eye) ophthalmic solution twice daily for 8 weeks. At weeks 1, 2, 3, 4, and 8, intraocular pressure (IOP) and adverse events were evaluated. Baseline mean IOP was 53.5 ± 3.4 mm Hg and mean IOP reductions of the last visit were -8.25 ± 1.2 mm Hg at 2 hours and -8.75 ± 2.2 mm Hg at 4 hours. Mean IOP reductions were clinically and statistically significant with 0.5% and 1.2% fasudil and peak effects occurred 2-4 hours after application (P = 0.0002). The largest IOP reductions were produced by 1.2% fasudil (up to -12 mm Hg). Conjunctival hyperemia was found in 1 patient with 1.2% fasudil. Topical administration of fasudil in end-stage primary open-angle glaucoma patients, caused reduction in IOP and was well tolerated. ROCK inhibitors could be considered as a candidate for glaucoma therapy in future.

GSK-3Beta-Dependent Activation of GEF-H1/ROCK Signaling Promotes LPS-Induced Lung Vascular Endothelial Barrier Dysfunction and Acute Lung Injury

The bacterial endotoxin or lipopolysaccharide (LPS) leads to the extensive vascular endothelial cells (EC) injury under septic conditions. Guanine nucleotide exchange factor-H1 (GEF-H1)/ROCK signaling not only involved in LPS-induced overexpression of pro-inflammatory mediator in ECs but also implicated in LPS-induced endothelial hyper-permeability. However, the mechanisms behind LPS-induced GEF-H1/ROCK signaling activation in the progress of EC injury remain incompletely understood. GEF-H1 localized on microtubules (MT) and is suppressed in its MT-bound state. MT disassembly promotes GEF-H1 release from MT and stimulates downstream ROCK-specific GEF activity. Since glycogen synthase kinase (GSK-3beta) participates in regulating MT dynamics under pathologic conditions, we examined the pivotal roles for GSK-3beta in modulating LPS-induced activation of GEF-H1/ROCK, increase of vascular endothelial permeability and severity of acute lung injury (ALI). In this study, we found that LPS induced human pulmonary endothelial cell (HPMEC) monolayers disruption accompanied by increase in GSK-3beta activity, activation of GEF-H1/ROCK signaling and decrease in beta-catenin and ZO-1 expression. Inhibition of GSK-3beta reduced HPMEC monolayers hyper-permeability and GEF-H1/ROCK activity in response to LPS. GSK-3beta/GEF-H1/ROCK signaling is implicated in regulating the expression of beta-catenin and ZO-1. In vivo, GSK-3beta inhibition attenuated LPS-induced activation of GEF-H1/ROCK pathway, lung edema and subsequent ALI. These findings present a new mechanism of GSK-3beta-dependent exacerbation of lung micro-vascular hyper-permeability and escalation of ALI via activation of GEF-H1/ROCK signaling and disruption of intracellular junctional proteins under septic condition.

Regulation of lung endothelial permeability and inflammatory responses by prostaglandin A2: role of EP4 receptor

PGA2 exhibits anti-inflammatory and barrier-protective effects on endothelial cells and in two mouse models of acute lung injury. PGA2-induced cytoskeletal remodeling and suppression of the NFκB pathway is mediated by prostanoid receptor EP4. Endothelial-specific EP4 knockout abolishes PGA2-protective effects in vitro and in vivo.

The role of prostaglandin A2 (PGA2) in modulation of vascular endothelial function is unknown. We investigated effects of PGA2 on pulmonary endothelial cell (EC) permeability and inflammatory activation and identified a receptor mediating these effects. PGA2 enhanced the EC barrier and protected against barrier dysfunction caused by vasoactive peptide thrombin and proinflammatory bacterial wall lipopolysaccharide (LPS). Receptor screening using pharmacological and molecular inhibitory approaches identified EP4 as a novel PGA2 receptor. EP4 mediated barrier-protective effects of PGA2 by activating Rap1/Rac1 GTPase and protein kinase A targets at cell adhesions and cytoskeleton: VE-cadherin, p120-catenin, ZO-1, cortactin, and VASP. PGA2 also suppressed LPS-induced inflammatory signaling by inhibiting the NFκB pathway and expression of EC adhesion molecules ICAM1 and VCAM1. These effects were abolished by pharmacological or molecular inhibition of EP4. In vivo, PGA2 was protective in two distinct models of acute lung injury (ALI): LPS-induced inflammatory injury and two-hit ALI caused by suboptimal mechanical ventilation and injection of thrombin receptor–activating peptide. These protective effects were abolished in mice with endothelial-specific EP4 knockout. The results suggest a novel role for the PGA2–EP4 axis in vascular EC protection that is critical for improvement of pathological states associated with increased vascular leakage and inflammation.

Conditional knockout of polarity complex (atypical) PKCι reveals an anti-inflammatory function mediated by NF-κB

Atypical PKC, Par6, and Par3 constitute a conserved complex signaling cell asymmetry. In contrast to its role in other tissues, atypical PKC inhibits NF-κB activation in epithelia and may function in maintaining low levels of inflammation in addition to establishing apicobasal polarity.

The conserved proteins of the polarity complex made up of atypical PKC (aPKC, isoforms ι and ζ), Par6, and Par3 determine asymmetry in several cell types, from Caenorhabditis elegans oocytes to vertebrate epithelia and neurons. We previously showed that aPKC is down-regulated in intestinal epithelia under inflammatory stimulation. Further, expression of constitutively active PKCι decreases NF-κB activity in an epithelial cell line, the opposite of the effect reported in other cells. Here we tested the hypothesis that aPKC has a dual function in epithelia, inhibiting the NF-κB pathway in addition to having a role in apicobasal polarity. We achieved full aPKC down-regulation in small intestine villi and colon surface epithelium using a conditional epithelium-specific knockout mouse. The results show that aPKC is dispensable for polarity after cell differentiation, except for known targets, including ROCK and ezrin, claudin-4 expression, and barrier permeability. The aPKC defect resulted in increased NF-κB activity, which could be rescued by IKK and ROCK inhibitors. It also increased expression of proinflammatory cytokines. In contrast, expression of anti-inflammatory IL-10 decreased. We conclude that epithelial aPKC acts upstream of multiple mechanisms that participate in the inflammatory response in the intestine, including, but not restricted to, NF-κB.

Yes-associated protein (YAP) signaling regulates lipopolysaccharide-induced tissue factor expression in human endothelial cells

BACKGROUND

Sepsis-induced acute lung injury (ALI) is characterized by fibrin deposition, which indicates the local activation of coagulation. Tissue factor (TF), expressed in the pulmonary microvasculature, acts as a critical initiator of blood coagulation and ALI in sepsis. The molecular mechanism of lipopolysaccharide (LPS)-induced TF expression in endothelial cells (ECs), however, has not been determined. In this study, we implicate the Rho-associated protein kinase (ROCK)/Yes associated protein (YAP)/early growth response (Egr-1) signaling pathway in LPS-induced TF expression in vitro and in sepsis-induced ALI in vivo.

METHODS

Human umbilical vein ECs incubated with LPS were pretreated with or without the ROCK inhibitor Y-27632, a YAP small, interfering RNA (siRNA) and an Egr-1 siRNA. ROCK, YAP and Egr-1 signaling-induced protein expression was investigated by Western blot. The LPS-induced activation of YAP was analyzed by an immunofluorescent assay. Furthermore, we intratracheally injected YAP siRNA to assess septic ALI in mice by hematoxylin and eosin staining.

RESULTS

LPS rapidly induced ROCK activation and increased TF expression in ECs. LPS caused YAP shuttling into the nuclei of ECs and combined with Egr-1 via the activation of ROCK. Furthermore, the LPS-mediated TF expression increase was prevented by ROCK inactivation, YAP knockdown and Egr-1 depletion, suggesting that LPS-induced TF expression is closely associated with the ROCK/YAP/Egr-1 signaling pathway in ECs. Finally, an intratracheal injection of YAP siRNA relieved lung injury in septic mice.

CONCLUSION

This study not only suggests that ROCK/YAP/Egr-1 signaling regulates TF expression after stimulation with LPS in ECs, but it also indicates that LPS-induced activation of YAP signaling plays an important role in septic ALI in mice. Our findings provide a new insight into the pathogenic mechanism of TF expression, which is closely linked to septic ALI, and YAP signaling is considered to be a novel target for therapeutic intervention under septic conditions.

Intravitreal Injection of a Rho-Kinase Inhibitor (Fasudil) for Recent-Onset Nonarteritic Anterior Ischemic Optic Neuropathy

This study evaluated the effects of intravitreal injection of fasudil (IVF), a Rho-kinase inhibitor, in cases of recent-onset nonarteritic anterior ischemic optic neuropathy (NAION). In this interventional case series, 13 eyes of 13 patients diagnosed with NAION within 14 days of onset were included. The affected eyes received a 0.025 mg/0.05 mL IVF. Functional and structural outcomes were assessed 1 and 3 months following treatment. Best corrected visual acuity (BCVA) was the main outcome measured, with mean deviation (MD) index of the VF test and peripapillary retinal nerve fiber layer thickness as secondary measures. There was a statistically significant improvement in the patients' BCVA 1 and 3 months following IVF; BCVA improved from 1.69 ± 0.55 logMAR at baseline to 0.98 ± 0.47 and 0.93 ± 0.51 logMAR at 1 and 3 months, respectively (P = .004). The change in BCVA was not significant between month 1 and month 3 (P = .22). Peripapillary retinal nerve fiber layer thickness decreased from 173.5 ± 29.28 µm in the baseline evaluation to 85.8 ± 8.8 µm at 1 month, and 62.9 ± 5.97 µm at 3 months (P = .003). MD values changed from 24.60 ± 3.80 to 21.0 ± 6.10 and 20.5 ± 6.50 at 1 and 3 months, respectively (P = .007 and .005, respectively). This pilot study suggests that IVF may be an effective treatment for patients with recent-onset NAION. Larger studies are required to establish the therapeutic role of fasudil for NAION.

Attenuation of lipopolysaccharide-induced lung vascular stiffening by lipoxin reduces lung inflammation

Reversible changes in lung microstructure accompany lung inflammation, although alterations in tissue micromechanics and their impact on inflammation remain unknown. This study investigated changes in extracellular matrix (ECM) remodeling and tissue stiffness in a model of LPS-induced inflammation and examined the role of lipoxin analog 15-epi-lipoxin A4 (eLXA4) in the reduction of stiffness-dependent exacerbation of the inflammatory process. Atomic force microscopy measurements of live lung slices were used to directly measure local tissue stiffness changes induced by intratracheal injection of LPS. Effects of LPS on ECM properties and inflammatory response were evaluated in an animal model of LPS-induced lung injury, live lung tissue slices, and pulmonary endothelial cell (EC) culture. In vivo, LPS increased perivascular stiffness in lung slices monitored by atomic force microscopy and stimulated expression of ECM proteins fibronectin, collagen I, and ECM crosslinker enzyme, lysyl oxidase. Increased stiffness and ECM remodeling escalated LPS-induced VCAM1 and ICAM1 expression and IL-8 production by lung ECs. Stiffness-dependent exacerbation of inflammatory signaling was confirmed in pulmonary ECs grown on substrates with high and low stiffness. eLXA4 inhibited LPS-increased stiffness in lung cross sections, attenuated stiffness-dependent enhancement of EC inflammatory activation, and restored lung compliance in vivo. This study shows that increased local vascular stiffness exacerbates lung inflammation. Attenuation of local stiffening of lung vasculature represents a novel mechanism of lipoxin antiinflammatory action.

Prostacyclin post-treatment improves LPS-induced acute lung injury and endothelial barrier recovery via Rap1

Protective effects of prostacyclin (PC) or its stable analog beraprost against agonist-induced lung vascular inflammation have been associated with elevation of intracellular cAMP and Rac GTPase signaling which inhibited the RhoA GTPase-dependent pathway of endothelial barrier dysfunction. This study investigated a distinct mechanism of PC-stimulated lung vascular endothelial (EC) barrier recovery and resolution of LPS-induced inflammation mediated by small GTPase Rap1. Efficient barrier recovery was observed in LPS-challenged pulmonary EC after prostacyclin administration even after 15 h of initial inflammatory insult and was accompanied by the significant attenuation of p38 MAP kinase and NFκB signaling and decreased production of IL-8 and soluble ICAM1. These effects were reproduced in cells post-treated with 8CPT, a small molecule activator of Rap1-specific nucleotide exchange factor Epac. By contrast, pharmacologic Epac inhibitor, Rap1 knockdown, or knockdown of cell junction-associated Rap1 effector afadin attenuated EC recovery caused by PC or 8CPT post-treatment. The key role of Rap1 in lung barrier restoration was further confirmed in the murine model of LPS-induced acute lung injury. Lung injury was monitored by measurements of bronchoalveolar lavage protein content, cell count, and Evans blue extravasation and live imaging of vascular leak over 6 days using a fluorescent tracer. The data showed significant acceleration of lung recovery by PC and 8CPT post-treatment, which was abrogated in Rap1a(-/-) mice. These results suggest that post-treatment with PC triggers the Epac/Rap1/afadin-dependent mechanism of endothelial barrier restoration and downregulation of p38MAPK and NFκB inflammatory cascades, altogether leading to accelerated lung recovery.

Zoledronate attenuates angiotensin II-induced abdominal aortic aneurysm through inactivation of Rho/ROCK-dependent JNK and NF-κB pathway

AIMS

Abdominal aortic aneurysm (AAA) is a life-threatening disease affecting almost 10% of the population over the age of 65. Nitrogen-containing bisphosphonates (N-BPs) have been shown to exert anti-atherogenic and anti-angiogenic effects, but the potential effects of N-BPs on AAA remain unclear. Here, we tested whether a potent N-BP, zoledronate, can attenuate the formation of Angiotensin II (Ang II)-induced AAA in hyperlipidaemic mice.

METHODS AND RESULTS

Low-density lipoprotein receptor(-/-) (LDLR(-/-)) mice infused for 28 days with Ang II were treated with placebo and 100 μg/kg/day zoledronate. Continuous Ang II infusion in LDLR(-/-) mice exhibited a 59% incidence of AAA formation, and treatment with zoledronate decreased AAA formation (21%). Compared with the saline group, administration of zoledronate in Ang II-infused LDLR(-/-) mice attenuated the expansion of the suprarenal aorta (maximal aortic diameter), reduced elastin degradation in the media layer of the aorta, and significantly diminished vascular inflammation by reduction in vascular cell adhesion molecule expression and macrophage accumulation. Treatment with zoledronate decreased matrix metalloproteinase-2 (MMP-2) in aortic tissues. Zoledronate-treated mice had significant down-regulation of JNK, NF-κB, and reduced Ang II-induced Rho/ROCK activation. Zoledronate reduced monocytes adherence to human aortic endothelial cells in vitro.

CONCLUSION

Zoledronate-attenuated Ang II induced AAA formation by suppression of MMP-2 activity and suppressed vascular inflammation and Ang II-induced Rho/ROCK activities.

Stiffness-activated GEF-H1 expression exacerbates LPS-induced lung inflammation

Acute lung injury (ALI) is accompanied by decreased lung compliance. However, a role of tissue mechanics in modulation of inflammation remains unclear. We hypothesized that bacterial lipopolysacharide (LPS) stimulates extracellular matrix (ECM) production and vascular stiffening leading to stiffness-dependent exacerbation of endothelial cell (EC) inflammatory activation and lung barrier dysfunction. Expression of GEF-H1, ICAM-1, VCAM-1, ECM proteins fibronectin and collagen, lysyl oxidase (LOX) activity, interleukin-8 and activation of Rho signaling were analyzed in lung samples and pulmonary EC grown on soft (1.5 or 2.8 kPa) and stiff (40 kPa) substrates. LPS induced EC inflammatory activation accompanied by expression of ECM proteins, increase in LOX activity, and activation of Rho signaling. These effects were augmented in EC grown on stiff substrate. Stiffness-dependent enhancement of inflammation was associated with increased expression of Rho activator, GEF-H1. Inhibition of ECM crosslinking and stiffening by LOX suppression reduced EC inflammatory activation and GEF-H1 expression in response to LPS. In vivo, LOX inhibition attenuated LPS-induced expression of GEF-H1 and lung dysfunction. These findings present a novel mechanism of stiffness-dependent exacerbation of vascular inflammation and escalation of ALI via stimulation of GEF-H1-Rho pathway. This pathway represents a fundamental mechanism of positive feedback regulation of inflammation.

Guanine nucleotide exchange factor-H1 signaling is involved in lipopolysaccharide-induced endothelial barrier dysfunction

BACKGROUND

Gram-negative bacterial lipopolysaccharide (LPS) leads to the pathologic increase of vascular leakage under septic conditions. However, the mechanisms behind LPS-induced vascular hyperpermeability remain incompletely understood. In this study, we tested hypothesis that guanine nucleotide exchange factor-H1 (GEF-H1) signaling might be a key pathway involved in endothelial cells (ECs) barrier dysfunction.

METHODS

The roles of GEF-H1 signaling pathway in LPS-induced ECs barrier dysfunction were accessed by Evans blue dye-labeled albumin (EB-albumin) leak across the human umbilical vein EC (HUVEC) monolayers and Western blot assays. Furthermore, the effect of GEF-H1 signaling on LPS-induced alteration of cytoskeletal proteins and disruption of cell-cell junctions were analyzed by immunofluorescent analysis and Western blot assays, respectively.

RESULTS

We found that LPS could rapidly activated GEF-H1/RhoA/Rho-associated protein kinase (ROCK) signaling pathway in ECs. The LPS-mediated increase in EB-albumin flux across human HUVECs monolayers could be prevented by GEF-H1 depletion or ROCK inactivation. ECs permeability is controlled by actin filaments and cell-cell contact protein complexes. Actin stress fiber formation and/or cell-cell contact proteins loss cause vascular barrier disruption. Here, GEF-H1 knockdown or ROCK inactivation both not only significantly inhibited LPS-induced actin stress fiber formation, phosphorylation of myosin light chain, and myosin-associated phosphatase type 1, but also suppressed LPS-induced loss of occludin, claudin-1, and vascular endothelial (VE)-cadherin in ECs, which suggested that LPS-induced stress fiber formation and cell-cell junctions disruption were closely associated with GEF-H1/RhoA/ROCK signaling activation.

CONCLUSION

Our findings indicate that GEF-H1/RhoA/ROCK pathway in ECs plays an important role in LPS-mediated alteration of cell morphology and disruption of cell-cell junctions, consequently regulate LPS-induced vascular permeability dysfunction.

Tetrandrine Suppresses Cancer Angiogenesis and Metastasis in 4T1 Tumor Bearing Mice

Metastasis remains the most deadly aspect of cancer and still evades direct treatment. Thus, there is a great need to develop new treatment regimens to suppress tumor cells that have escaped surgical removal or that may have already disseminated. We have found that tetrandrine (TET) exhibits anticolon cancer activity. Here, we investigate the inhibition effect of TET to breast cancer metastasis, angiogenesis and its molecular basis underlying TET's anticancer activity. We compare TET with chemotherapy drug doxorubicin in 4T1 tumor bearing BALB/c mice model and find that TET exhibits an anticancer metastatic and antiangiogenic activities better than those of doxorubicin. The lung metastatic sites were decreased by TET, which is confirmed by bioluminescence imaging in vivo. On the other hand, laser doppler perfusion imaging (LDI) was used for measuring the blood flow of tumor in 4T1-tumor bearing mice. As a result, the local blood perfusion of tumor was markedly decreased by TET after 3 weeks. Mechanistically, TET treatment leads to a decrease in p-ERK level and an increase in NF-κB levels in HUVECs. TET also regulated metastatic and angiogenic related proteins, including vascular endothelial growth factor, hypoxia-inducible factor-1α, integrin β5, endothelial cell specific molecule-1, and intercellular adhesion molecule-1 in vivo.

Lipopolysaccharide induces endoplasmic store Ca2+-dependent inflammatory responses in lung microvessels

The pulmonary microvasculature plays a critical role in endotoxin-induced acute lung injury. However, the relevant signaling remain unclear. Specifically the role of endothelial Ca²⁺ in the induction of endotoxin-mediated responses in lung microvessels remains undefined. Toward elucidating this, we used the isolated blood-perfused rat lung preparation. We loaded microvessels with the Ca²⁺ indicator, Fura 2 AM and then determined Ca²⁺ responses to infusions of lipopolysaccharide (LPS) into the microvessels. LPS induced a more than two-fold increase in the amplitude of cytosolic Ca²⁺ oscillations. Inhibiting inositol 1,4,5 trisphosphate receptors on endoplasmic reticulum (ER) Ca²⁺ stores with Xestospongin C (XeC), blocked the LPS-induced increase in the Ca²⁺ oscillation amplitude. However, XeC did not affect entry of external Ca²⁺ via plasma membrane Ca²⁺ channels in lung microvascular endothelial cells. This suggested that LPS augmented the oscillations via release of Ca²⁺ from ER stores. In addition, XeC also blocked LPS-mediated activation and nuclear translocation of nuclear factor-kappa B in lung microvessels. Further, inhibiting ER Ca²⁺ release blunted increases in intercellular adhesion molecule-1 expression and retention of naïve leukocytes in LPS-treated microvessels. Taken together, the data suggest that LPS-mediated Ca²⁺ release from ER stores underlies nuclear factor-kappa B activation and downstream inflammatory signaling in lung microvessels. Thus, we show for the first time a role for inositol 1,4,5 trisphosphate-mediated ER Ca²⁺ release in the induction of LPS responses in pulmonary microvascular endothelium. Mechanisms that blunt this signaling may mitigate endotoxin-induced morbidity.

Rho guanine exchange factors in blood vessels: fine-tuners of angiogenesis and vascular function

The angiogenic cascade is a multi-step process essential for embryogenesis and other physiological and pathological processes. Rho family GTPases are binary molecular switches and serve as master regulators of various basic cellular processes. Rho GTPases are known to exert important functions in angiogenesis and vascular physiology. These functions demand a tight and context-specific control of cellular processes requiring superordinate control by a multitude of guanine nucleotide exchange factors (GEFs). GEFs display various features enabling them to fine-tune the actions of Rho GTPases in the vasculature: (1) GEFs regulate specific steps of the angiogenic cascade; (2) GEFs show a spatio-temporally specific expression pattern; (3) GEFs differentially regulate endothelial function depending on their subcellular location; (4) GEFs mediate crosstalk between complex signaling cascades and (5) GEFs themselves are regulated by another layer of interacting proteins. The aim of this review is to provide an overview about the role of GEFs in regulating angiogenesis and vascular function and to point out current limitations as well as clinical perspectives.

Apolipoprotein E-knockout mice show increased titers of serum anti-nuclear and anti-dsDNA antibodies

Apolipoprotein E-knockout (ApoE(-/-)) mice, atherosclerosis-prone mice, show an autoimmune response, but the pathogenesis is not fully understood. We investigated the pathogenesis in female and male ApoE(-/-) mice. The spleens of all ApoE(-/-) and C57BL/6 (B6) mice were weighed. The serum IgG level and titers of anti-nuclear antibody (ANA) and anti-double-stranded DNA (anti-dsDNA) antibody were assayed by ELISA. Apoptosis of spleen tissue was evaluated by TUNEL. TLR4 level in spleen tissue was tested by immunohistochemistry and Western blot analysis. Levels of MyD88, p38, phosphorylated p38 (pp38), interferon regulatory factor 3 (IRF3) and Bcl-2-associated X protein (Bax) in spleen tissue were detected by Western blot analysis. We also survey the changes of serum autoantibodies, spleen weight, splenocyte apoptosis and the expressions of TLR4, MyD88, pp38, IRF3 and Bax in spleen tissue in male ApoE(-/-) mice after 4weeks of lipopolysaccharide (LPS), Toll-like receptor 4 ligand, administration. ApoE(-/-) mice showed splenomegaly and significantly increased serum level of IgG and titers of ANA and anti-dsDNA antibody as compared with B6 mice. Splenocyte apoptosis and the expression of TLR4, MyD88, pp38, IRF3 and Bax in spleen tissue were significantly lower in ApoE(-/-) than B6 mice. The expression of TLR4, MyD88, IRF3, pp38, and Bax differed by sex in ApoE(-/-) spleen tissue. The down-regulation of TLR4 signal molecules induced by LPS led to decreased expression of Bax and increased serum titers of ANA and anti-dsDNA antibody. Therefore, the TLR4 signal pathway may participate in maintaining the balance of splenocyte apoptosis and autoantibody production in ApoE(-/-) mice.