LPS tolerance in human endothelial cells: reduced PMN adhesion, E-selectin expression, and NF-kappaB mobilization

Heterogeneous Patterns of Endothelial NF-κB p65 and MAPK c-Jun Activation, Adhesion Molecule Expression, and Leukocyte Recruitment in Lung Microvasculature of Mice with Sepsis

BACKGROUND

Sepsis is an uncontrolled systemic inflammatory response to an infection that can result in acute failure of the function of the lung called acute respiratory distress syndrome. Leukocyte recruitment is an important hallmark of acute lung failure in patients with sepsis. Endothelial cells (EC) participate in this process by facilitating tethering, rolling, adhesion, and transmigration of leukocytes via adhesion molecules on their cell surface. In in vivo studies, endothelial nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65 and mitogen-activated protein kinase (MAPK) c-Jun intracellular signal transduction pathways were reported to regulate the expression of adhesion molecules.

METHODS

Mice underwent cecal ligation and puncture (CLP) to induce polymicrobial sepsis and were sacrificed at different time points up to 72 h after sepsis onset. Immunohistochemistry and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analyses were used to determine the kinetics of nuclear localization of p65 and c-Jun in EC, expression and location of adhesion molecules E-selectin and vascular cell adhesion molecule 1 (VCAM-1). Furthermore, the extent and location of leukocyte recruitment were assessed based on Ly6G staining of neutrophils, cluster determinant (CD) 3 staining of T lymphocytes, and CD68 staining of macrophages.

RESULTS

In all pulmonary microvascular beds, we identified p65 and c-Jun nuclear accumulation in a subset of endothelial cells within the first 24 h after CLP-sepsis initiation. E-selectin protein was expressed in a subset of microvessels at 4 and 7 h after sepsis initiation, while VCAM-1 was expressed in a scattered pattern in alveolar tissue and microvessels, without discernible changes during sepsis development. CLP-induced sepsis predominantly promoted the accumulation of neutrophils and T lymphocytes 4 and 7 h after disease onset. Neutrophil accumulation occurred in all pulmonary microvascular beds, while T lymphocytes were present in alveolar tissue and postcapillary venules. Taken together, nuclear localization of p65 and c-Jun in EC and neutrophil recruitment could be associated with induced E-selectin expression in the pulmonary microvessels in CLP-septic mice at the early stage of the disease. In alveolar capillaries, on the other hand, activation of these molecular pathways and leukocyte accumulation occurred in the absence of E-selectin or VCAM-1.

CONCLUSIONS

Endothelial activation and leukocyte recruitment in sepsis-induced lung injury are regulated by multiple, heterogeneously controlled mechanisms, which vary depending on the type of microvascular bed involved.

Hypoxia inducible factor-1α regulates microglial innate immune memory and the pathology of Parkinson's disease

Neuroinflammation is one of the core pathological features of Parkinson's disease (PD). Innate immune cells play a crucial role in the progression of PD. Microglia, the major innate immune cells in the brain, exhibit innate immune memory effects and are recognized as key regulators of neuroinflammatory responses. Persistent modifications of microglia provoked by the first stimuli are pivotal for innate immune memory, resulting in an enhanced or suppressed immune response to second stimuli, which is known as innate immune training and innate immune tolerance, respectively. In this study, LPS was used to establish in vitro and in vivo models of innate immune memory. Microglia-specific Hif-1α knockout mice were further employed to elucidate the regulatory role of HIF-1α in innate immune memory and MPTP-induced PD pathology. Our results showed that different paradigms of LPS could induce innate immune training or tolerance in the nigrostriatal pathway of mice. We found that innate immune tolerance lasting for one month protected the dopaminergic system in PD mice, whereas the effect of innate immune training was limited. Deficiency of HIF-1α in microglia impeded the formation of innate immune memory and exerted protective effects in MPTP-intoxicated mice by suppressing neuroinflammation. Therefore, HIF-1α is essential for microglial innate immune memory and can promote neuroinflammation associated with PD.

Comparative and Temporal Characterization of LPS and Blue-Light-Induced TLR4 Signal Transduction and Gene Expression in Optogenetically Manipulated Endothelial Cells

In endothelial cells (ECs), stimulation of Toll-like receptor 4 (TLR4) by the endotoxin lipopolysaccharide (LPS) induces the release of diverse pro-inflammatory mediators, beneficial in controlling bacterial infections. However, their systemic secretion is a main driver of sepsis and chronic inflammatory diseases. Since distinct and rapid induction of TLR4 signaling is difficult to achieve with LPS due to the specific and non-specific affinity to other surface molecules and receptors, we engineered new light-oxygen-voltage-sensing (LOV)-domain-based optogenetic endothelial cell lines (opto-TLR4-LOV LECs and opto-TLR4-LOV HUVECs) that allow fast, precise temporal, and reversible activation of TLR4 signaling pathways. Using quantitative mass-spectrometry, RT-qPCR, and Western blot analysis, we show that pro-inflammatory proteins were not only expressed differently, but also had a different time course when the cells were stimulated with light or LPS. Additional functional assays demonstrated that light induction promoted chemotaxis of THP-1 cells, disruption of the EC monolayer and transmigration. In contrast, ECs incorporating a truncated version of the TLR4 extracellular domain (opto-TLR4 ΔECD2-LOV LECs) revealed high basal activity with fast depletion of the cell signaling system upon illumination. We conclude that the established optogenetic cell lines are well suited to induce rapid and precise photoactivation of TLR4, allowing receptor-specific studies.

Association between age and the host response in critically ill patients with sepsis

BACKGROUND

The association of ageing with increased sepsis mortality is well established. Nonetheless, current investigations on the influence of age on host response aberrations are largely limited to plasma cytokine levels while neglecting other pathophysiological sepsis domains like endothelial cell activation and function, and coagulation activation. The primary objective of this study was to gain insight into the association of ageing with aberrations in key host response pathways and blood transcriptomes in sepsis.

METHODS

We analysed the clinical outcome (n = 1952), 16 plasma biomarkers providing insight in deregulation of specific pathophysiological domains (n = 899), and blood leukocyte transcriptomes (n = 488) of sepsis patients stratified according to age decades. Blood transcriptome results were validated in an independent sepsis cohort and compared with healthy individuals.

RESULTS

Older age was associated with increased mortality independent of comorbidities and disease severity. Ageing was associated with lower endothelial cell activation and dysfunction, and similar inflammation and coagulation activation, despite higher disease severity scores. Blood leukocytes of patients ≥ 70 years, compared to patients < 50 years, showed decreased expression of genes involved in cytokine signaling, and innate and adaptive immunity, and increased expression of genes involved in hemostasis and endothelial cell activation. The diminished expression of gene pathways related to innate immunity and cytokine signaling in subjects ≥ 70 years was sepsis-induced, as healthy subjects ≥ 70 years showed enhanced expression of these pathways compared to healthy individuals < 50 years.

CONCLUSIONS

This study provides novel evidence that older age is associated with relatively mitigated sepsis-induced endothelial cell activation and dysfunction, and a blood leukocyte transcriptome signature indicating impaired innate immune and cytokine signaling. These data suggest that age should be considered in patient selection in future sepsis trials targeting the immune system and/or the endothelial cell response.

Survey of extracellular communication of systemic and organ-specific inflammatory responses through cell free messenger RNA profiling in mice

Background

Inflammatory and immune responses are essential and dynamic biological processes that protect the body against acute and chronic adverse stimuli. While conventional protein markers have been used to evaluate systemic inflammatory response, the immunological response to stimulation is complex and involves modulation of a large set of genes and interacting signalling pathways of innate and adaptive immune systems. There is a need for a non-invasive tool that can comprehensively evaluate and monitor molecular dysregulations associated with inflammatory and immune responses in circulation and in inaccessible solid organs.

Methods

Here we utilized cell-free messenger RNA (cf-mRNA) RNA-Seq whole transcriptome profiling and computational biology to temporally assess lipopolysaccharide (LPS) induced and JAK inhibitor modulated inflammatory and immune responses in mouse plasma samples.

Findings

Cf-mRNA profiling displayed a pattern of systemic immune responses elicited by LPS and dysregulation of associated pathways. Moreover, attenuation of several inflammatory pathways, including STAT and interferon pathways, were observed following the treatment of JAK inhibitor. We further identified the dysregulation of liver-specific transcripts in cf-mRNA which reflected changes in the gene-expression pattern in this generally inaccessible biological compartment.

Interpretation

Using a preclinical mouse model, we demonstrated the potential of plasma cf-mRNA profiling for systemic and organ-specific characterization of drug-induced molecular alterations that are associated with inflammatory and immune responses.

Funding

Molecular Stethoscope.

Therapeutic Effects of Retinoic Acid in Lipopolysaccharide-Induced Cardiac Dysfunction: Network Pharmacology and Experimental Validation

Purpose

Sepsis, which is deemed as a systemic inflammation reaction syndrome in the face of infectious stimuli, is the primary cause of death in ICUs. Sepsis-induced cardiomyopathy (SIC) may derive from systemic inflammation reaction and oxidative stress. Retinoic acid (RA) is recognized by its beneficial roles in terms of the immunoresponse to infections and antioxygen actions. However, the treatment efficacy and potential causal links of RA in SIC are still elusive.

Methods

By virtue of the STITCH database, we identified the targets of RA. Differentially expressed genes in SIC were acquired from the GEO database. The PPI network of intersected targets was established. GO and KEGG pathway enrichment analysis was completed. Hub genes were analyzed by cytoHubba plug-in. In the process of experimental validation, a mouse sepsis model was established by lipopolysaccharide (LPS), and the treated mice were intraperitoneally injected with RA or Dexamethasone (DEX) 60 min prior to LPS injections. Survival conditions, cardiac functions and antioxidant levels of the mice were assessed. Cardiac inflammation and injury were detected by HE and TUNEL. The levels of key genes and signal pathway expression were analyzed by RT-PCR and Western blot.

Results

PPARA, ITGAM, VCAM-1, IGF-1 and IL-6 were identified as key therapeutic targets of RA by network pharmacology. PI3K-Akt signaling pathway is the main regulatory pathway of RA. In vivo researches unraveled that RA can improve the survival rate and cardiac function of LPS-treated mice, inhibit inflammatory factors and myocardial injury, and regulate the expression of key therapeutic targets and key pathways, which is PI3K-Akt signaling pathway.

Conclusion

Network pharmacological method offers a predicative strategy to explore the treatment efficacy and causal links of RA in endotoxemic myocarditis. Through experimental verification, we discover that RA can reduce lipopolysaccharide-induced cardiac dysfunction by regulating the PI3K-Akt signaling pathway and key genes.

The Methyltransferase Smyd1 Mediates LPS-Triggered Up-Regulation of IL-6 in Endothelial Cells

The lysine methyltransferase Smyd1 with its characteristic catalytic SET-domain is highly enriched in the embryonic heart and skeletal muscles, participating in cardiomyogenesis, sarcomere assembly and chromatin remodeling. Recently, significant Smyd1 levels were discovered in endothelial cells (ECs) that responded to inflammatory cytokines. Based on these biochemical properties, we hypothesized that Smyd1 is involved in inflammation-triggered signaling in ECs and therefore, investigated its role within the LPS-induced signaling cascade. Human endothelial cells (HUVECs and EA.hy926 cells) responded to LPS stimulation with higher intrinsic Smyd1 expression. By transfection with expression vectors containing gene inserts encoding either intact Smyd1, a catalytically inactive Smyd1-mutant or Smyd1-specific siRNAs, we show that Smyd1 contributes to LPS-triggered expression and secretion of IL-6 in EA.hy926 cells. Further molecular analysis revealed this process to be based on two signaling pathways: Smyd1 increased the activity of NF-κB and promoted the trimethylation of lysine-4 of histone-3 (H3K4me3) within the IL-6 promoter, as shown by ChIP-RT-qPCR combined with IL-6-promoter-driven luciferase reporter gene assays. In summary, our experimental analysis revealed that LPS-binding to ECs leads to the up-regulation of Smyd1 expression to transduce the signal for IL-6 up-regulation via activation of the established NF-κB pathway as well as via epigenetic trimethylation of H3K4.

Intra-vital imaging of mesenchymal stromal cell kinetics in the pulmonary vasculature during infection

Mesenchymal stem/stromal cells (MSCs) have demonstrated efficacy in pre-clinical models of inflammation and tissue injury, including in models of lung injury and infection. Rolling, adhesion and transmigration of MSCs appears to play a role during MSC kinetics in the systemic vasculature. However, a large proportion of MSCs become entrapped within the lungs after intravenous administration, while the initial kinetics and the site of arrest of MSCs in the pulmonary vasculature are unknown. We examined the kinetics of intravascularly administered MSCs in the pulmonary vasculature using a microfluidic system in vitro and intra-vital microscopy of intact mouse lung. In vitro, MSCs bound to endothelium under static conditions but not under laminar flow. VCAM-1 antibodies did not affect MSC binding. Intravital microscopy demonstrated MSC arrest at pulmonary micro-vessel bifurcations due to size obstruction. Retention of MSCs in the pulmonary microvasculature was increased in Escherichia coli-infected animals. Trapped MSCs deformed over time and appeared to release microvesicles. Labelled MSCs retained therapeutic efficacy against pneumonia. Our results suggest that MSCs are physically obstructed in pulmonary vasculature and do not display properties of rolling/adhesion, while retention of MSCs in the infected lung may require receptor interaction.

Inhibiting DNA Methylation Improves Survival in Severe Sepsis by Regulating NF-κB Pathway

Organ dysfunction caused by sepsis is life-threatening and results in high mortality. Therapeutic options for sepsis are limited. Pathogenic factors are considered as components of environmental pressure that modify DNA methylation patterns thereby enhancing disease progression. Here, we found that sepsis patients exhibited higher levels of genomic DNA methylation patterns and hypermethylated genes associated with the NF-kB signaling pathway. Therefore, we hypothesized that a DNA methyl transferase inhibitor, Decitabine, may mitigate inflammation and improve survival by inhibiting the NF-κB signaling pathway. To test the hypothesis, mice challenged with caecal ligation and puncture (CLP) were subcutaneously injected with Decitabine solution (0.5, 1, and 1.5 mg/kg) 2 h following operation. Our results indicated that Decitabine reduces DNA methyltransferases (DNMTs), attenuates NF-κB activation, downregulates inflammatory cytokine levels, and inhibits the progression of sepsis. Thus, DNA methylation may be indispensable for sepsis and serve as a predicting factor. The use of Decitabine could represent a novel strategy in the treatment of sepsis.

In vitro Impact of Yeast Expressed Hybrid Peptide CATH-2TP5 as a Prophylactic Measure Toward Sepsis and Inflammation

CATH-2TP5 is a linear cationic hybrid peptide, consequent from naturally occurring antimicrobial peptide (AMPs) Cathelicidin-2 (CATH-2) and Immunomodulatory peptide Thymopentin (TP5) having dynamic and potent anti-inflammatory activities without hemolytic effect. The biocompatible mechanism of CATH-2TP5 is favored to explore new methodologies in the direction of biomedical applications. In this retrospectively study, an antiendotoxin and anti-inflammatory hybrid peptide CATH-2TP5 was emulated into pPICZα-A and successfully expressed in Pichia pastoris (P. pastoris). The recombinant CATH-2TP5 was purified through the Ni-affinity column and reversed-phase HPLC. The purified CATH-2TP5 peptide exhibited robust anti-endotoxin activity and significantly (p < 0.05) neutralized the effect of lipopolysaccharide (LPS). Furthermore, the down-regulated effect of CATH-2TP was more pronounced (p < 0.05) on LPS-induced cytotoxic effects, nitric oxide secretion and pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) in murine RAW264.7 macrophages. As associated to control and parental peptide the number of apoptotic cells was also contracted with the treatment of CATH-2TP5. Thus, we concluded that CATH-2TP5 peptide may be used in various biomedical applications as a therapeutic drug.

Expression and Purification of Hybrid LL-37Tα1 Peptide in Pichia pastoris and Evaluation of Its Immunomodulatory and Anti-inflammatory Activities by LPS Neutralization

This study pertains to the new approach for the development of hybrid peptide LL-37Tα1 and its biomedical applications. A linear cationic hybrid peptide, LL-37Tα1 was derived from two parental peptides (LL-37 and Tα1) recognized as potent anti-endotoxin without any hemolytic or cytotoxic activity. We successfully cloned the gene of hybrid peptide LL-37Tα1 in PpICZαA vector and expressed in the Pichia pastoris. The recombinant peptide was purified by Ni-affinity column and reverse-phase high performance liquid chromatography (RP-HPLC) with an estimated molecular mass of 3.9 kDa as determined by SDS-PAGE and mass spectrometry. We analyzed the LPS neutralization by limulus amebocyte lysate (LAL) activity and the results indicate that the hybrid peptide LL-37Tα1 directly binds endotoxin and significantly (p < 0.05) neutralizes the effect of LPS in a dose-dependent manner. Lactate dehydrogenase (LDH) assay revealed that LL-37Tα1 successfully reduces the LPS-induced cytotoxicity in mouse RAW264.7 macrophages. Moreover, it significantly (p < 0.05) decreased the levels of nitric oxide, proinflammatory cytokines including TNF-α, IL-6, IL-1β, and diminished the number of apoptotic cells in LPS-stimulated mouse RAW264.7 macrophages. Our results suggest that the P. pastoris expression system is cost-effective for commercial production of the immunomodulatory and anti-inflammatory hybrid peptide (IAHP) LL-37Tα1 and the peptide may serve as effective anti-endotoxin/anti-inflammatory agent with minimal cytotoxicity.

Forkhead Box C2 Attenuates Lipopolysaccharide-Induced Cell Adhesion via Suppression of Intercellular Adhesion Molecule-1 Expression in Human Umbilical Vein Endothelial Cells

Atherosclerosis is a chronic vascular inflammatory disease that involves diverse cell types and circulating regulatory factors, including intercellular adhesion molecule (ICAM)-1, a proinflammatory cytokine. Lipopolysaccharides (LPS) increase ICAM-1 expression and promote cell adhesion, but the mechanism is not clear. We found that LPS induced time- and dose-regulated upregulation of ICAM-1 expression and downregulation of forkhead box protein C2 (Foxc2) expression in human umbilical vein endothelial cells (HUVECs). Overexpression of Foxc2 significantly inhibited both LPS-induced ICAM-1 expression in HUVECs and LPS-induced adhesion of THP-1 cells to HUVECs. Foxc2 siRNA dramatically increased both LPS-induced ICAM-1 expression and LPS-induced adhesion of THP-1 human monocytes cells to HUVECs. We conclude that Foxc2 inhibited LPS-induced adhesion of THP-1 cells to HUVECs by suppressing ICAM-1 expression in HUVECs.

Cynandione A inhibits lipopolysaccharide-induced cell adhesion via suppression of the protein expression of VCAM‑1 in human endothelial cells

Cynandione A (CA) is one of the most active compounds in the roots of Cynanchum wilfordii, the extracts of which have been used extensively in East Asia to treat various diseases including anti‑ischemic stroke. In the present study, the anti‑adherent activity of CA in lipopolysaccharide (LPS)‑stimulated human umbilical vascular endothelial cells (HUVECs) was investigated. CA markedly reduced the expression of vascular adhesion molecule‑1 (VCAM‑1) by LPS in HUVECs. The results also demonstrated that CA significantly reduced the expression of pro‑inflammatory and chemoattractant cytokines, including interleukin (IL)‑1β, IL‑6, IL‑8, monocyte chemoattractant protein‑1 and tumor necrosis factor‑α, in LPS‑activated human endothelial cells. CA inhibited the phosphorylation of mitogen‑activated protein kinases, including the extracellular signal‑regulated kinase 1/2 and p38 kinases. It was found that CA decreased the IKK/IκB‑α phosphorylation of inhibitor of nuclear factor (NF)‑κB kinase/inhibitor of NF‑κB‑α, suppressed translocation of the NF‑κB p65 subunit into the nucleus and inhibited the transcriptional activity of NF‑κB. CA also decreased human monocyte cell adhesion to endothelial cells in LPS‑stimulated conditions. These results demonstrated that CA inhibited the protein expression of VCAM‑1 and pro‑inflammatory cytokines by suppressing the transcriptional activity of NF‑κB. The results also suggested that CA may be important in the development of anti‑inflammatory drugs by inhibiting the expression of cell adhesion molecules.

p21 mediates macrophage reprogramming through regulation of p50-p50 NF-κB and IFN-β

M1 and M2 macrophage phenotypes, which mediate proinflammatory and antiinflammatory functions, respectively, represent the extremes of immunoregulatory plasticity in the macrophage population. This plasticity can also result in intermediate macrophage states that support a balance between these opposing functions. In sepsis, M1 macrophages can compensate for hyperinflammation by acquiring an M2-like immunosuppressed status that increases the risk of secondary infection and death. The M1 to M2 macrophage reprogramming that develops during LPS tolerance resembles the pathological antiinflammatory response to sepsis. Here, we determined that p21 regulates macrophage reprogramming by shifting the balance between active p65-p50 and inhibitory p50-p50 NF-κB pathways. p21 deficiency reduced the DNA-binding affinity of the p50-p50 homodimer in LPS-primed and -rechallenged macrophages, impairing their ability to attenuate IFN-β production and acquire an M2-like hyporesponsive status. High p21 levels in sepsis patients correlated with low IFN-β expression, and p21 knockdown in human monocytes corroborated its role in IFN-β regulation. The data demonstrate that p21 adjusts the equilibrium between p65-p50 and p50-p50 NF-κB pathways to mediate macrophage plasticity in LPS tolerance. Identifying p21-related pathways involved in monocyte reprogramming may lead to potential targets for sepsis treatment.

Human Host Defense Cathelicidin Peptide LL-37 Enhances the Lipopolysaccharide Uptake by Liver Sinusoidal Endothelial Cells without Cell Activation

The liver is a major organ that removes waste substances from the blood, and liver sinusoidal endothelial cells (LSECs) are professional scavenger cells, which incorporate and degrade various endogenous and exogenous molecules including pathogenic factor LPS. Mammalian cells express a number of peptide antibiotics that function as effectors in the innate host defense systems. LL-37, a human cathelicidin antimicrobial peptide, has a potent LPS-neutralizing activity and exhibits protective actions on various infection models. However, the effect of LL-37 on the LPS clearance has not been clarified. In this study, to further understand the host-protective mechanism of LL-37, we evaluated the effect of LL-37 on the LPS clearance in vitro. LL-37 enhanced the LPS uptake by human LSECs. Of interest, LL-37 was similarly incorporated into LSECs both in the presence and the absence of LPS, and the incorporated LPS and LL-37 were colocalized in LSECs. Importantly, the uptake of LPS and LL-37 was inhibited by endocytosis inhibitors, heparan sulfate proteoglycan analogs, and glycosaminoglycan lyase treatment of the cells. Moreover, the uptake of LL-37-LPS did not activate TLR4 signaling in both MyD88-dependent and -independent pathways. In addition, the incorporated LL-37-LPS was likely transported to the lysosomes in LSECs. Together these observations suggest that LL-37 enhances the LPS uptake by LSECs via endocytosis through the complex formation with LPS and the interaction with cell-surface heparan sulfate proteoglycans, thereby facilitating the intracellular incorporation and degradation of LPS without cell activation. In this article, we propose a novel function of LL-37 in enhancing LPS clearance.

Chitosan oligosaccharides downregulate the expression of E-selectin and ICAM-1 induced by LPS in endothelial cells by inhibiting MAP kinase signaling

The expression of adhesion molecules in endothelial cells elicited by lipopolysaccharide (LPS) is involved in the adhesive interaction between endothelial cells and monocytes in inflammation. In this study, in order to characterize the anti-inflammatory effects of chitosan oligosaccharides (COS) on LPS‑induced inflammation and to elucidate the underlying mechanisms, the mRNA levels of E-selectin and intercellular adhesion molecule-1 (ICAM-1) were measured in porcine iliac artery endothelial cells (PIECs). When these cells were treated with COS, the LPS-induced mRNA expression of E-selectin and ICAM-1 was reduced through the inhibition of the signal transduction cascade, p38 mitogen‑activated protein kinase (MAPK)/extracellular regulated protein kinase 1/2 (ERK1/2) and nuclear factor-κB (NF-κB). Moreover, through the inhibition of p38 MAPK and ERK1/2, COS suppressed the LPS-induced NF-κB p65 translocation. We found that COS suppressed the phosphorylation of p38 MAPK and the translocation of NF-κB p65 into the nucleus in a dose-dependent manner, and inhibited the adhesion of U973 cells to PIECs. Based on these results, it can be concluded that COS downregulate the expression of E-selectin and ICAM-1 by inhibiting the phosphorylation of MAPKs and the activation of NF-κB in LPS-treated PIECs. Our study demonstrates the valuable anti-inflammatory properties of COS.

Sex differences in endothelial function of aged hypertriglyceridemic rats - effect of atorvastatin treatment

The aim of the study was to test the hypothesis that the effect of atorvastatin on endothelium-dependent relaxation of the superior mesenteric artery (SMA) may differ in male vs. female aged hypertriglyceridemic rats (HTGs). Experiments were performed on 11-month-old male and female Prague hereditary HTGs. Atorvastatin (ATO) was administered p.o. in the dose of 0.30 mg/100g/day. Controls received vehiculum. After two months of ATO administration blood pressure, serum triglycerides (TG) and total cholesterol (CHOL) were determined. Endothelial function of SMA was studied in vitro using evaluation of relaxant responses of precontracted SMA to acetylcholine. The serum TG of control male HTGs were found to be statistically higher than those of female controls, while CHOL and blood pressure did not share gender differences. Responses of SMA of female control HTGs were statistically decreased compared to their male counterparts. ATO treatment induced decrease in blood pressure and TG of both males and females, yet CHOL values were reduced only in females. The protective effect of ATO on SMA endothelial function was much more pronounced in females compared to males. We conclude that vascular endothelial dysfunction of aged HTG rats is more severe and more attenuated by ATO in females compared to males. The protective effect of ATO on vascular endothelial function does not seem to depend solely on its lipid lowering action.

E-selectin mediated adhesion and migration of endothelial colony forming cells is enhanced by SDF-1α/CXCR4

Objective

Endothelial-colony forming cells (ECFCs) can be readily expanded from human umbilical cord blood and can facilitate repair of endothelial injury. E-selectin and SDF-1α are produced following endothelial injury and can regulate endothelial progenitor homing. Mechanisms of vascular repair specific to the mode of injury have not been well described in homogenous cell populations such as ECFCs and are needed for development of more effective vascular repair strategies.

Methods and Results

Lipopolysaccharide (LPS)-induced endotoxic injury to mature human umbilical vein endothelial cells (HUVEC) was compared with hypoxic and radiation injury. E-selectin expression in HUVEC cells is markedly increased (208-fold) following LPS-induced injury and facilitates increased ECFC adhesion and migration function in vitro. SDF-1α expression remains unchanged in LPS-treated HUVEC cells but increases more than 2 fold in fibroblasts undergoing similar endotoxic injury. SDF-1α induces expression of E-selectin ligands on ECFCs and facilitates greater E-selectin-mediated adhesion and migration of ECFCs in a CXCR4-dependent manner. Induction of E-selectin expression in HUVECs following hypoxic or radiation injury is negligible, however, while SDF-1α is increased markedly following hypoxia, highlighting injury-specific synergism between mediators of vascular repair.

Conclusion

E-selectin mediates adhesion and migration of ECFCs following endotoxic endothelial injury. SDF-1α augments E-selectin mediated ECFC adhesion and migration in a CXCR4-dependent manner.

Impaired function of Fanconi anemia type C-deficient macrophages

FA is a genetic disorder characterized by BM failure, developmental defects, and cancer predisposition. Previous studies suggest that FA patients exhibit alterations in immunologic function. However, it is unclear whether the defects are immune cell-autonomous or secondary to leukopenia from evolving BM failure. Given the central role that macrophages have in the innate immune response, inflammation resolution, and antigen presentation for acquired immunity, we examined whether macrophages from Fancc-/- mice exhibit impaired function. Peritoneal inflammation induced by LPS or sodium periodate resulted in reduced monocyte/macrophage recruitment in Fancc-/- mice compared with WT controls. Fancc-/- mice also had decreased inflammatory monocytes mobilized into the peripheral blood after LPS treatment compared with controls. Furthermore, Fancc-/- peritoneal macrophages displayed cell-autonomous defects in function, including impaired adhesion to FN or endothelial cells, reduced chemoattractant-mediated migration, and decreased phagocytosis. Moreover, dysregulated F-actin rearrangement was detected in Fancc-/- macrophages after adhesion to FN, which was consistent with an observed reduction in RhoA-GTP levels. Importantly, these data suggest that impaired cytoskeletal rearrangements in Fancc-/- macrophages may be the common mechanism responsible for cell-autonomous defects detected in vitro, as well as altered monocyte/macrophage trafficking in vivo.

Human anti-microbial cathelicidin peptide LL-37 suppresses the LPS-induced apoptosis of endothelial cells

Sepsis is a systemic disease resulting from harmful host response to bacterial infections. During the exacerbation of severe sepsis or septic shock, apoptosis of endothelial cells is induced in susceptible organs such as the lung and liver and triggers microcirculatory disorder and organ dysfunction. LPS, an outer membrane component of Gram-negative bacteria, is one of the major virulence factors for the pathogenesis. We previously reported that LL-37, a human anti-microbial cathelicidin peptide, potently neutralizes the biological activity of LPS and protects mice from lethal endotoxin shock. However, the effect of LL-37 on the LPS-induced endothelial cell apoptosis remains to be clarified. In this study, to further elucidate the action of LL-37 on severe sepsis/endotoxin shock, we investigated the effects of LL-37 on the LPS-induced endothelial cell apoptosis in vitro and in vivo using lung-derived normal human microvascular blood vessel endothelial cells (HMVEC-LBls) and D-galactosamine hydrochloride (D-GalN)-sensitized murine endotoxin shock model. LL-37 suppressed the LPS-induced apoptosis of HMVEC-LBls. In addition, LL-37 inhibited the binding of LPS possibly to the LPS receptors (CD14 and toll-like receptor 4) expressed on the cells. Thus, LL-37 can suppress the LPS-induced apoptosis of HMVEC-LBls via the inhibition of LPS binding to the cells. Furthermore, LL-37 drastically suppressed the apoptosis of hepatic endothelial cells as well as hepatocytes in the liver of murine endotoxin shock model. Together, these observations suggest that LL-37 could suppress the LPS-induced apoptosis of endothelial cells, thereby attenuating lethal sepsis/endotoxin shock.

The Toll-like receptor 4 agonist monophosphoryl lipid a augments innate host resistance to systemic bacterial infection

Monophosphoryl lipid A (MPLA) is a Toll-like receptor 4 (TLR4) agonist that is currently used as a vaccine adjuvant in humans. In this study, we evaluated the effect of MPLA treatment on the innate immune response to systemic bacterial infections in mice. Mice treated with MPLA after burn injury showed improved survival and less local and systemic dissemination of bacteria in a model of Pseudomonas aeruginosa burn wound infection. Prophylactic treatment with MPLA significantly enhanced bacterial clearance at the site of infection and reduced systemic dissemination of bacteria despite causing attenuation of proinflammatory cytokine production during acute intra-abdominal infection caused by cecal ligation and puncture. Administration of MPLA at 1 h after CLP also improved bacterial clearance but did not alter cytokine production. MPLA treatment increased the numbers of granulocytes, double-positive myeloid cells, and macrophages at sites of infection and increased the percentage and total numbers of myeloid cells mediating phagocytosis of bacteria. Depletion of Ly6G(+) neutrophils, but not macrophages, eliminated the ability of MPLA treatment to improve bacterial clearance. The immunomodulatory effects of MPLA were absent in TLR4-deficient mice. In conclusion, these studies show that MPLA treatment significantly augments the innate immune response to bacterial infection by enhancing bacterial clearance despite the attenuation of proinflammatory cytokine production. The enhanced bacterial clearance is mediated, in part, by increased numbers of myeloid cells with effective phagocytic functions at sites of infection and is TLR4 dependent.

Cancer protection of soy resembles cancer protection during pregnancy

It has been established that carrying a pregnancy to full-term at an early age can protect against contracting cancer by up to 50% in later life. The trophoblast theory of cancer states that trophoblast and cancer tissue are very similar. New findings suggest that the loss of fetal cells during pregnancy resemble those cells responsible for causing metastasis in cancer. Fetal cells and spreading cancer cells are highly proliferative. They are similar to stem cells, exhibiting no or low hormone receptor expression, and require a hormone receptor independent mechanism for control. Control of membrane stability during pregnancy is of vital importance for a successful pregnancy and is mediated by androstenediol and 2-methoxyestradiol. 2-Methoxyestradiol has no hormone receptor affinity and elicits strong anticancer effects particularly against cancer stem cells and fetal cells, for which currently no treatment has yet been established. There is a discussion whether pregnancy reduces cancer stem cells in the breast. Soy isoflavones are structurally similar to both hormones, and elicit strong anticancer effects and antiangiogenesis via inhibition of NF-κB, even in hormone receptor independent breast cancers seen in epidemiologic studies. The trophoblast theory of cancer could help to explain why soy baby nutrition formulas have no effect on baby physiology, other than the nutritional aspect, although soy elicits many effects on the adult immune system. To survive the immune system of the mother, the immune system of the fetus has to be separated; otherwise, the reduction of the immune system in the mother, a necessary feature for the blastocyst to grow, would immediately reduce the immunity for the fetus and endanger its survival. Similar to a fetus, newly born babies show immune insensitive to Th1 and Th2 cytokines, which are necessary and crucial for regulating the immune system of the mother, thus raising the risk of the baby of developing allergies and neurodermatitis. Gene expression studies in vitro as well as in circulating tumor cells from patients consuming a fermented soy product support the antiangiogenic as well as antiproliferative effects of soy.

CORM-3-derived CO modulates polymorphonuclear leukocyte migration across the vascular endothelium by reducing levels of cell surface-bound elastase

Recently, it has been shown that carbon monoxide (CO)-releasing molecule (CORM)-released CO can suppress inflammation. In this study, we assessed the effects and potential mechanisms of a ruthenium-based water-soluble CO carrier [tricarbonylchloroglycinate-ruthenium(II) (CORM-3)] in the modulation of polymorphonuclear leukocyte (PMN) inflammatory responses in an experimental model of sepsis. Sepsis in mice was induced by cecal ligation and puncture. CORM-3 (3 mg/kg iv) was administered 15 min after the induction of cecal ligation and puncture. PMN accumulation in the lung (myeloperoxidase assay), bronchoalveolar lavage (BAL) fluid, and lung vascular permeability (protein content in BAL fluid) were assessed 6 h later. In in vitro experiments, human PMNs were primed with LPS (10 ng/ml) and subsequently stimulated with formyl-methionyl-leucylphenylalanine (fMLP; 100 nM). PMN production of ROS (L-012/dihydrorhodamine-123 oxidation), degranulation (release of elastase), and PMN rolling, adhesion, and migration to/across human umbilical vein endothelial cells (HUVECs) were assessed in the presence or absence of CORM-3 (1-100 muM). The obtained results indicated that systemically administered CORM-3 attenuates PMN accumulation and vascular permeability in the septic lung. Surprisingly, in in vitro experiments, treatment of PMNs with CORM-3 further augmented LPS/fMLP-induced ROS production and the release of elastase. The latter effects, however, were accompanied by an inability of PMNs to mobilize elastase to the cell surface (plasma membrane), an event required for efficient PMN transendothelial migration. The CORM-3-induced decrease in cell surface levels of elastase was followed by decreased PMN rolling/adhesion to HUVECs and complete prevention of PMN migration across HUVECs. In contrast, treatment of HUVECs with CORM-3 had no effect on PMN transendothelial migration. Taken together, these findings indicate that, in sepsis, CORM3-released CO, while further amplifying ROS production and degranulation of PMNs, concurrently reduces the levels of cell surface-bound elastase, which contributes to suppressed PMN transendothelial migration.

Regulation of basal core promoter activity of human organic cation transporter 1 (OCT1/SLC22A1)

Human organic cation transporter 1 (OCT1/SLC22A1) plays important roles in the hepatic uptake of cationic drugs. The functional characteristics of this transporter have been well evaluated, but molecular information regarding transcriptional regulation is limited. In the present study, therefore, we examined the gene regulation of OCT1 gene focusing on basal core expression. An approximately 2.5-kb fragment of the OCT1 promoter region was isolated, and promoter activity was measured by luciferase assay in the human liver cell lines Huh7 and HepG2. Deletion analysis suggested that the region spanning -141/-69 was essential for the basal core transcriptional activity and that this region contained the sequence of a cognate E-box (CACGTG). The E-box is known to be bound by the basal transcription factors, upstream stimulating factors (USFs), and the functional involvements of USF1 and USF2 were confirmed by a transactivation effect, a mutational analysis of the E-box, and an electrophoretic mobility shift assay. The transactivation effect of USFs on the OCT1 promoter was further stimulated by hepatocyte nuclear factor 4alpha, a liver-enriched transcription factor. There were no polymorphisms in the proximal promoter region (about 400 bp) of OCT1 gene (n = 109). These findings indicated that both USF1 and USF2 bind to an E-box sequence located in the OCT1 core promoter region and are required for the basal gene expression of this transporter.

Carbon monoxide liberated from carbon monoxide-releasing molecule CORM-2 attenuates inflammation in the liver of septic mice

Recent studies suggest that exogenously administered CO is beneficial for the resolution of acute inflammation. In this study, we assessed the role of CO liberated from a systemically administered tricarbonyldichlororuthenium-(II)-dimer (CORM-2) on modulation of liver inflammation during sepsis. Polymicrobial sepsis in mice was induced by cecal ligation and perforation (CLP). CORM-2 (8 mg/kg iv) was administered immediately after CLP induction, and neutrophil [polymorphonuclear leukocyte (PMN)] tissue accumulation, activation of transcription factor, NF-kappaB, and changes in adhesion molecule ICAM-1 expression (inflammation-relevant markers) were assessed in murine liver 24 h later. In addition, the effects and potential mechanisms of CORM-2-released CO in modulation of vascular endothelial cell proinflammatory responses were assessed in vitro. To this end, human umbilical vein endothelial cells (HUVEC) were stimulated with LPS (1 microg/ml) in the presence or absence of CORM-2 (10-100 microM) and production of intracellular reactive oxygen species (ROS), (DHR123 oxidation) and NO (DAF-FM nitrosation) and subsequent activation of NF-kappaB were assessed 4 h later. In parallel, expression of ICAM-1 and inducible NO synthase (iNOS) proteins along with PMN adhesion to LPS-challenged HUVEC were also assessed. Induction of CLP resulted in increased PMN accumulation, ICAM-1 expression, and activation of NF-kappaB in the liver of septic mice. These effects were significantly attenuated by systemic administration of CORM-2. In in vitro experiments, CORM-2-released CO attenuated LPS-induced production of ROS and NO, activation of NF-kappaB, increase in ICAM-1 and iNOS protein expression and PMN adhesion to LPS-stimulated HUVEC. Taken together, these findings indicate that CO released from systemically administered CORM-2 provides anti-inflammatory effects by interfering with NF-kappaB activation and subsequent downregulation of proadhesive vascular endothelial cell phenotype in the liver of septic mice.

Critical roles of Sp1 in gene expression of human and rat H+/organic cation antiporter MATE1

A H+/organic cation antiporter (multidrug and toxin extrusion 1: MATE1/SLC47A1) plays important roles in the tubular secretion of various clinically important cationic drugs such as cimetidine. We have recently found that the regulation of this transporter greatly affects the pharmacokinetic properties of cationic drugs in vivo. No information is available about the regulatory mechanisms for the MATE1 gene. In the present study, therefore, we examined the gene regulation of human (h) and rat (r) MATE1, focusing on basal expression. A deletion analysis suggested that the regions spanning -65/-25 and -146/-38 were essential for the basal transcriptional activity of the hMATE1 and rMATE1 promoter, respectively, and that both regions contained putative Sp1-binding sites. Functional involvement of Sp1 was confirmed by Sp1 overexpression, a mutational analysis of Sp1-binding sites, mithramycin A treatment, and an electrophoretic mobility shift assay. Furthermore, we found a single nucleotide polymorphism (SNP) in the promoter region of hMATE1 (G-32A), which belongs to a Sp1-binding site. The allelic frequency of this rSNP was 3.7%, and Sp1-binding and promoter activity were significantly decreased. This is the first study to clarify the transcriptional mechanisms of the MATE1 gene and to identify a SNP affecting the promoter activity of hMATE1.

Cl−-dependent upregulation of human organic anion transporters: different effects on transport kinetics between hOAT1 and hOAT3

Chloride ion has a stimulatory effect on the transport of organic anions across renal basolateral membranes. However, the exact mechanisms at molecular levels have been unclear as of yet. Human organic anion transporters hOAT1 and hOAT3 play important roles in renal basolateral membranes. In this study, the effects of Cl− on the activities of these transporters were evaluated by using HEK293 cells stably expressing hOAT1 or hOAT3 (HEK-hOAT1 or HEK-hOAT3). The uptake of p-[14C]aminohippurate by HEK-hOAT1 and [3H]estrone sulfate by HEK-hOAT3 was greater in the presence of Cl− than in the presence of SO42− or gluconate. Additionally, the uptake of various compounds by HEK-hOAT1 and HEK-hOAT3 was significantly higher in the Cl−-containing medium than the gluconate-containing medium, suggesting that the influences of Cl− are not dependent on substrate and that Cl− directly stimulates the functions of hOAT1 and hOAT3. The substitution of gluconate with Cl− did not change the Km value for the uptake of p-[14C]aminohippurate by HEK-hOAT1 but caused an approximately threefold increase in the maximal uptake rate (Vmax) value. On the other hand, replacement of gluconate with Cl− decreased the Km value for the uptake of [3H]estrone sulfate and cefotiam by HEK-hOAT3 to about one-third, while it did not change the Vmax value. In summary, Cl− upregulates the activities of both hOAT1 and hOAT3, but its effects on transport kinetics differ between these transporters. It was suggested that Cl− participates in the trans-location process for hOAT1, and the substrate recognition process for hOAT3.

Combined proteomic and metabonomic studies in three genetic forms of the renal Fanconi syndrome

The renal Fanconi syndrome is a defect of proximal tubular function causing aminoaciduria and low-molecular-weight proteinuria. Dent's disease and Lowe syndrome are defined X-linked forms of Fanconi syndrome; there is also an autosomal dominant idiopathic form (ADIF), phenotypically similar to Dent's disease though its gene defect is still unknown. To assess whether their respective gene products are ultimately involved in a common reabsorptive pathway for proteins and low-molecular-mass endogenous metabolites, we compared renal Fanconi urinary proteomes and metabonomes with normal (control) urine using mass spectrometry and (1)H-NMR spectroscopy, respectively. Urine from patients with low-molecular-weight proteinuria secondary to ifosfamide treatment (tubular proteinuria; TP) was also analyzed for comparison. All four of the disorders studied had characteristic proteomic and metabonomic profiles. Uromodulin was the most abundant protein in normal urine, whereas Fanconi urine was dominated by albumin. (1)H-NMR spectroscopic data showed differences in the metabolic profiles of Fanconi urine vs. normal urine, due mainly to aminoaciduria. There were differences in the urinary metabolite and protein compositions between the three genetic forms of Fanconi syndrome: cluster analysis grouped the Lowe and Dent's urinary proteomes and metabonomes together, whereas ADIF and TP clustered together separately. Our findings demonstrate a distinctive "polypeptide and metabolite fingerprint" that can characterize the renal Fanconi syndrome; they also suggest that more subtle and cause-specific differences may exist between the different forms of Fanconi syndrome that might provide novel insights into the underlying mechanisms and cellular pathways affected.

NF-kappaB regulation of endothelial cell function during LPS-induced toxemia and cancer

The transcription factor NF-kappaB is an important regulator of homeostatic growth and inflammation. Although gene-targeting studies have revealed important roles for NF-kappaB, they have been complicated by component redundancy and lethal phenotypes. To examine the role of NF-kappaB in endothelial tissues, Tie2 promoter/enhancer-IkappaBalpha(S32A/S36A) transgenic mice were generated. These mice grew normally but exhibited enhanced sensitivity to LPS-induced toxemia, notable for an increase in vascular permeability and apoptosis. Moreover, B16-BL6 tumors grew significantly more aggressively in transgenic mice, underscoring a new role for NF-kappaB in the homeostatic response to cancer. Tumor vasculature in transgenic mice was extensive and disorganized. This correlated with a marked loss in tight junction formation and suggests that NF-kappaB plays an important role in the maintenance of vascular integrity and response to stress.

Heterogeneity in lipopolysaccharide responsiveness of endothelial cells identified by gene expression profiling: role of transcription factors

Interindividual differences of endothelial cells in response to endotoxins might contribute to the diversity in clinical outcome among septic patients. The present study was conducted to test the hypothesis that endothelial cells (EC) with high and low proinflammatory potential exist and to dissect the molecular basis underlying this phenomenon. Thirty human umbilical vein endothelial cell (HUVEC) lines were stimulated for 24 h with lipopolysaccharide (LPS) and screened for interleukin (IL)-8 production. Based on IL-8 production five low and five high producers, tentatively called types I and II responders, respectively, were selected for genome-wide gene expression profiling. From the 74 genes that were modulated by LPS in all type II responders, 33 genes were not influenced in type I responders. Among the 41 genes that were increased in both responders, 17 were expressed significantly stronger in type II responders. Apart from IL-8, significant differences in the expression of proinflammatory related genes between types I and II responders were found for adhesion molecules [intercellular adhesion molecule (ICAM-1), E-selectin)], chemokines [monocyte chemoattractant protein (MCP-1), granulocyte chemotactic protein (GCP-2)], cytokines (IL-6) and the transcription factor CCAAT/enhancer binding protein-delta (C/EBP-delta). Type I responders also displayed a low response towards tumour necrosis factor (TNF)-alpha. In general, maximal activation of nuclear factor (NF)-kappaB was achieved in type I responders at higher concentrations of LPS compared to type II responders. In the present study we demonstrate that LPS-mediated gene expression differs quantitatively and qualitatively in types I and II responders. Our results suggest a pivotal role for common transcription factors as a low inflammatory response was also observed after TNF-alpha stimulation. Further studies are required to elucidate the relevance of these findings in terms of clinical outcome in septic patients.

Lipopolysaccharide signaling in endothelial cells

Sepsis is the systemic immune response to severe bacterial infection. The innate immune recognition of bacterial and viral products is mediated by a family of transmembrane receptors known as Toll-like receptors (TLRs). In endothelial cells, exposure to lipopolysaccharide (LPS), a major cell wall constituent of Gram-negative bacteria, results in endothelial activation through a receptor complex consisting of TLR4, CD14 and MD2. Recruitment of the adaptor protein myeloid differentiation factor (MyD88) initiates an MyD88-dependent pathway that culminates in the early activation of nuclear factor-kappaB (NF-kappaB) and the mitogen-activated protein kinases. In parallel, a MyD88-independent pathway results in a late-phase activation of NF-kappaB. The outcome is the production of various proinflammatory mediators and ultimately cellular injury, leading to the various vascular sequelae of sepsis. This review will focus on the signaling pathways initiated by LPS binding to the TLR4 receptor in endothelial cells and the coordinated regulation of this pathway.

Adenovirus stimulates choline efflux by increasing expression of organic cation transporter-2

We examined the effect of wild-type human adenovirus (Ad5) on choline transport in murine lung epithelia (MLE) and in rodent primary alveolar type II cells. Cells were active in pH-sensitive, reversible transport of choline, a process blocked pharmacologically with phenoxybenzamine, an inhibitor of organic cation transporters (OCT). PCR products for the choline transporters, OCT-1 and OCT-2, were detected, but only OCT-2 protein was robustly expressed within MLE and primary alveolar epithelial cells. Ad5 produced a two- to threefold increase in choline efflux from cells, resulting in a significant reduction in intracellular choline content and its major product, phosphatidylcholine. Effects of Ad5 on choline efflux were inhibited with phenoxybenzamine, and choline efflux was attenuated by OCT-2 small interfering RNA. Adenovirus also produced a dose-dependent increase in immunoreactive OCT-2 levels concomitant with increased cellular OCT-2 steady-state mRNA. These results indicate that adenoviruses can significantly disrupt choline trafficking in lung epithelia by upregulating expression of an alveolar protein involved in organic cation transport.

Molecular and cellular physiology of renal organic cation and anion transport

Organic cations and anions (OCs and OAs, respectively) constitute an extraordinarily diverse array of compounds of physiological, pharmacological, and toxicological importance. Renal secretion of these compounds, which occurs principally along the proximal portion of the nephron, plays a critical role in regulating their plasma concentrations and in clearing the body of potentially toxic xenobiotics agents. The transepithelial transport involves separate entry and exit steps at the basolateral and luminal aspects of renal tubular cells. It is increasingly apparent that basolateral and luminal OC and OA transport reflects the concerted activity of a suite of separate transport processes arranged in parallel in each pole of proximal tubule cells. The cloning of multiple members of several distinct transport families, the subsequent characterization of their activity, and their subcellular localization within distinct regions of the kidney now allows the development of models describing the molecular basis of the renal secretion of OCs and OAs. This review examines recent work on this issue, with particular emphasis on attempts to integrate information concerning the activity of cloned transporters in heterologous expression systems to that observed in studies of physiologically intact renal systems.

Novel slc22 transporter homologs in fly, worm, and human clarify the phylogeny of organic anion and cation transporters

Slc22 family organic anion and cation transporters (OATs, OCTs, and OCTNs) are transmembrane proteins expressed predominantly in kidney and liver. These proteins mediate the uptake or excretion of numerous physiologically (and pharmacologically) important compounds, and accordingly have been the focus of intensive study. Here we investigate the molecular phylogeny of the slc22 transporters, identifying homologs in Drosophila and C. elegans, several of which are developmentally regulated, as well as reporting the cloning of a novel human family member, UST6, expressed exclusively in liver in both embryo and adult. The latter helps define a subfamily within the OATs, which appears to have human- and rodent-specific members, raising potential issues with respect to the use of rodents as models for the transport of organic anions (which include many pharmaceuticals) in humans. Although this phylogenetic inference could not be made on the basis of sequence alignment, analysis of intron phasing suggests that the OAT, OCT, and OCTN lineages of the slc22 family formed after the divergence of vertebrates and invertebrates. Subsequently, these lineages expanded through independent tandem duplications to produce multiple gene pairs. After analyzing over 200 other transporter genes, we find such pairing to be relatively specific to vertebrate organic anion and cation transporters, suggesting selection for gene pairing operating within this family in particular. This might reflect a requirement for redundancy or broader substrate specificity in vertebrates (compared to invertebrates), due to their greater physiological complexity and thus potentially broader exposure to organic ions.

Action of EGF and PGE2on basolateral organic anion uptake in rabbit proximal renal tubules and hOAT1 expressed in human kidney epithelial cells

We recently showed that, in a proximal tubule cell line (opossum kidney cells), epithelial growth factor (EGF) stimulates basolateral organic anion transport (OAT) via ERK1/2, arachidonic acid, phospholipase A2, and generation of prostaglandins. PGE2binds the prostanoid receptor and, thus, activates adenylate cyclase and PKA, which stimulate basolateral organic anion uptake. In the present study, we investigated whether this regulatory cascade is also true 1) for ex vivo conditions in isolated renal proximal (S2) tubules from rabbit and 2) in a human renal epithelial cell line stably expressing human OAT1 (IHKE-hOAT1). EGF activated ERK1/2 in S2 tubules and IHKE-hOAT1, and, in both cases, inhibition of ERK activation (by U-0126) abolished this stimulation. In S2 tubules and IHKE-hOAT1, EGF led to an increase of organic anion uptake, which again was inhibited by U-0126. PGE2stimulated basolateral organic anion uptake in rabbit S2 tubules and IHKE-hOAT1. EGF- and PGE2-mediated stimulation of organic anion uptake was abolished by inhibition of PKA in rabbit S2 tubules and IHKE-hOAT1, respectively. We conclude that 1) stimulation of basolateral organic anion uptake by EGF or PGE2is a widespread (if not general) regulatory mechanism, 2) the signal transduction pathway involved seems to be general, 3) stimulation of basolateral organic anion uptake by EGF or PGE2is also present under ex vivo conditions and, thus, is not a cell culture artifact, 4) activation of OAT1 is sufficient to explain the stimulatory effects of EGF and PGE2in opossum kidney cells and rabbit S2 segments, and 5) stimulation of basolateral OAT1 by EGF or PGE2is also important in humans and, thus, may have clinical implications.

Porphyromonas gingivalis lipopolysaccharide antagonizes Escherichia coli lipopolysaccharide at toll-like receptor 4 in human endothelial cells

E. coli lipopolysaccharide (LPS) induces cytokine and adhesion molecule expression via the toll-like receptor 4 (TLR4) signaling complex in human endothelial cells. In the present study, we investigated the mechanism by which Porphyromonas gingivalis LPS antagonizes E. coli LPS-dependent activation of human endothelial cells. P. gingivalis LPS at 1 micro g/ml inhibited both E. coli LPS (10 ng/ml) and Mycobacterium tuberculosis heat shock protein (HSP) 60.1 (10 micro g/ml) stimulation of E-selectin mRNA expression in human umbilical vein endothelial cells (HUVEC) without inhibiting interleukin-1 beta (IL-1beta) stimulation. P. gingivalis LPS (1 micro g/ml) also blocked both E. coli LPS-dependent and M. tuberculosis HSP60.1-dependent but not IL-1beta-dependent activation of NF-kappaB in human microvascular endothelial (HMEC-1) cells, consistent with antagonism occurring upstream from the TLR/IL-1 receptor adaptor protein, MyD88. Surprisingly, P. gingivalis LPS weakly but significantly activated NF-kappaB in HMEC-1 cells in the absence of E. coli LPS, and the P. gingivalis LPS-dependent agonism was blocked by transient expression of a dominant negative murine TLR4. Pretreatment of HUVECs with P. gingivalis LPS did not influence the ability of E. coli LPS to stimulate E-selectin mRNA expression. Taken together, these data provide the first evidence that P. gingivalis LPS-dependent antagonism of E. coli LPS in human endothelial cells likely involves the ability of P. gingivalis LPS to directly compete with E. coli LPS at the TLR4 signaling complex.

Mechanisms of endotoxin tolerance in human intestinal microvascular endothelial cells

Lipopolysaccharide (endotoxin) tolerance is well described in monocytes and macrophages, but is less well characterized in endothelial cells. Because intestinal microvascular endothelial cells exhibit a strong immune response to LPS challenge and play a critical regulatory role in gut inflammation, we sought to characterize the activation response of these cells to repeated LPS exposure. Primary cultures of human intestinal microvascular endothelial cells (HIMEC) were stimulated with LPS over 6-60 h and activation was assessed using U937 leukocyte adhesion, expression of E-selectin, ICAM-1, VCAM-1, IL-6, IL-8, manganese superoxide dismutase, HLA-DR, and CD86. Effect of repeat LPS stimulation on HIMEC NF-kappaB and mitogen-activated protein kinase (MAPK) activation, generation of superoxide anion, and Toll-like receptor 4 expression was characterized. LPS pretreatment of HIMEC for 24-48 h significantly decreased leukocyte adhesion after subsequent LPS stimulation. LPS pretreatment inhibited expression of E-selectin, VCAM-1, IL-6, and CD86, while ICAM-1, IL-8, and HLA-DR were not altered. Manganese superoxide dismutase expression increased with repeated LPS stimulation, with a reduction in intracellular superoxide. NF-kappaB activation was transiently inhibited by LPS pretreatment for 6 h, but not at later time points. In contrast, p44/42 MAPK, p38 MAPK, and c-Jun N-terminal kinase activation demonstrated inhibition by LPS pretreatment 24 or 48 h prior. Toll-like receptor 4 expression on HIMEC was not altered by LPS. HIMEC exhibit endotoxin tolerance after repeat LPS exposure in vitro, characterized by diminished activation and intracellular superoxide anion concentration, and reduced leukocyte adhesion. HIMEC possess specific mechanisms of immunoregulatory hyporesponsiveness to repeated LPS exposure.

PMN transendothelial migration decreases nuclear NFkappaB in IL-1beta-activated endothelial cells: role of PECAM-1

During the systemic inflammatory response, circulating cytokines interact with the vascular endothelium, resulting in activation and nuclear accumulation of the nuclear transcription factor, nuclear factor kappa B (NFkappaB). In turn, NFkappaB transactivates relevant proinflammatory genes, resulting in an amplification of the inflammatory response. Because this scenario is potentially detrimental to the host, mechanisms exist to limit this amplification. Using an in vitro system that mimics the vascular-interstitial interface during inflammation (cell culture inserts), we provide evidence for the existence of a novel negative feedback mechanism on NFkappaB activity. We show that the interleukin 1beta-induced accumulation of nuclear NFkappaB in human umbilical vein endothelial cell monolayers is dramatically reduced when polymorphonuclear leukocytes (PMN) are allowed to migrate across these monolayers. This effect does not appear to be due to PMN-derived elastase or nitric oxide. Fixed PMN (adhere but do not migrate) did not affect nuclear NFkappaB. Furthermore, cross-linking of platelet-endothelial cell adhesion molecule-1 (PECAM-1), but not intercellular adhesion molecule-1, reduces human umbilical vein endothelial cell nuclear NFkappaB induced by interleukin 1beta. Finally, interaction of PMN with PECAM-1-deficient endothelial cells does not reduce nuclear NFkappaB. These observations indicate that engagement of PECAM-1 by emigrating PMN is a pivotal event in this negative feedback on NFkappaB activity.

Alpha-melanocyte stimulating hormone prevents lipopolysaccharide-induced vasculitis by down-regulating endothelial cell adhesion molecule expression

The neuroendocrine hormone alpha-melanocyte stimulating hormone (MSH) has profound antiinflammatory and immunomodulating properties. Here we have examined the possibility that alpha-MSH may interfere with the expression and function of cell adhesion molecules (CAMs) expressed by human dermal microvascular endothelial cells (HDMECs) in response to lipopolysaccharide (LPS) or TNFalpha in vitro and in vivo. In HDMEC, alpha-MSH (10(-8)/10(-12) M) profoundly reduced the mRNA and protein expression of E-selectin, vascular CAM (VCAM)-1, and intercellular CAM (ICAM)-1 induced by LPS or TNFalpha as determined by semiquantitative RT-PCR, ELISA, and fluorescence-activated cell sorter analysis. In addition, alpha-MSH significantly impaired the LPS-induced ICAM-1 and VCAM-1-mediated adhesion of lymphocytes to HDMEC monolayer in a functional adhesion assay. Likewise, alpha-MSH effectively inhibited the transcription factor nuclear factor-kappaB activation in HDMEC, which is required for CAM gene expression. Importantly in vivo, in murine LPS-induced cutaneous vasculitis (local Shwartzman reaction), a single ip injection of alpha-MSH significantly suppressed the deleterious vascular damage and hemorrhage by inhibiting the sustained expression of vascular E-selectin and VCAM-1. This persistent expression has been implicated in the dysregulation of diapedesis and activation of leukocytes, which subsequently leads to hemorrhagic vascular damage. Our findings indicate that alpha-MSH may have an important therapeutical potential for the treatment of vasculitis, sepsis, and inflammatory diseases.

Endotoxin protection from oxygen toxicity: effect on pulmonary neutrophils and L-selectin

The mechanisms by which sublethal doses of endotoxin protect against hyperoxic lung injury are not completely understood. We hypothesized that endotoxin treatment would result in a decreased inflammatory response to hyperoxia and that this would be accompanied by activation of neutrophils (as evidenced by loss of L-selectin) in the peripheral circulation. Adult rats were injected with endotoxin 0.5 mg/kg prior to and 24 hr after onset of exposure to > or = 98% O2. After 56 hr of hyperoxia, pulmonary neutrophils were lower in the O2/endotoxin group compared to O2 controls as measured by myeloperoxidase in lung homogenates and neutrophil counts in bronchoalveolar lavage fluid. Circulating neutrophils were also significantly lower in the O2/endotoxin group compared to O2 controls at 56 hr. Expression of the neutrophil adhesion molecule, L-selectin, was lower at 4 and 24 hr in the endotoxin-treated rats compared to O2 controls. There were no differences at 48 hr. Expression of CD18 rose significantly in the O2/endotoxin group after 4 hr, but thereafter did not differ from O2 controls. In summary, endotoxin protection from O2 toxicity was associated with reduced neutrophils in the lung and a loss of L-selectin from peripheral blood neutrophils.

Role of p38 MAPK in ICAM-1 expression of vascular endothelial cells induced by lipopolysaccharide

Lipopolysaccharide (LPS) stimulation of endothelial cells induces the expression of intercellular adhesion molecule-1 (ICAM-1), a critical adhesion molecule involved in the adhesive interaction between leukocytes and endothelial cells in shock and inflammation. Although there is little literature about role of p38 mitogen-activated protein kinase (MAPK) in ICAM-1 protein expression of LPS-induced endothelial cells, it is still not defined whether gene transcription is regulated by p38 MAPK in ICAM-1 expression of LPS-induced endothelial cells. In this study, the potential role of p38 MAPK in ICAM-1 expression of LPS-induced endothelial cells was studied in vitro and in vivo. In vitro studies, the results showed that compared with basic expression of ICAM-1 protein on cultured human umbilical vein endothelial cells (HUVECs), the ICAM-1 expression was increased initially at 2 h after LPS stimulation, reached peak value at 24 h, and descended at 36 h obviously. A dose-dependent relationship existed between LPS concentration and ICAM-1 expression. The abundance of ICAM-1 mRNA in cytoplasma of endothelial cells was upregulated significantly by LPS stimulation at 2 h and was maintained at a high level from 4 to 36 h. The upregulation of ICAM-1 protein and mRNA expression of LPS-induced HUVECs was markedly inhibited by SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole], a highly specific inhibitor of p38 MAPK. Activity of p38 MAPK in HUVECs was increased at 15 min after LPS stimulation and reached the maximum at 60 min, then descended significantly. Activity of p38 MAPK was inhibited significantly by SB203580 in vitro. In vivo studies, administration of SB203580 (12.5 or 25 mg/kg, per ora) markedly reduced LPS-induced expression of ICAM-1 protein and mRNA of lung tissues of male BALB/c mice. These data highlight that the upregulation of ICAM-1 expression of LPS-induced endothelial cells in vitro and in vivo is mediated by p38 MAPK pathway at the level of gene transcription. The ICAM-1 expression of LPS-induced endothelial cells is characteristic of time dependence and dose dependence, and tolerates to chronic LPS stimulation. Inhibition of the p38 MAPK signal pathway may be used as an approach to attenuate ICAM-1 production in the treatment of septic shock.

Monocyte intracellular cytokine production during human endotoxaemia with or without a second in vitro LPS challenge: effect of RWJ-67657, a p38 MAP-kinase inhibitor, on LPS-hyporesponsiveness

In the present study, we investigated the effect of RWJ-67657, a p38 MAP kinase inhibitor, upon in vivo LPS-induced monocyte cytokine production and upon monocyte LPS-hyporesponsiveness. Thirty minutes before a single injection of LPS (4 ng/kg BW), healthy male volunteers received a single oral dose of RWJ-67657 at increasing dosages (0-1400 mg). Blood samples (pre-medication, 3, 6 and 24 h after LPS) were immediately incubated with LPS (reflecting LPS-hyporesponsiveness) or without LPS (reflecting in vivo monocyte stimulation) for 4 h at 37 degrees C. Following red blood cells lysis and white blood cell permeabilization, cells were labelled with alpha-CD14-FITC and alpha-IL-1beta, alpha-IL-12 or alpha-TNFalpha (PE-labelled), fixed, and analysed using flow cytometry. In vivo LPS injection resulted in an increased percentage of circulating monocytes producing IL-1beta, TNFalpha and IL-12 only at 3 h after the LPS injection. This was dose-dependently inhibited by RWJ-67657 treatment. LPS-hyporesponsiveness to in vitro LPS treatment was most prominent at 3 and 6 h after the in vivo LPS injection; compared with pre-medication monocytes, at these intervals a reduced percentage of monocytes produced IL-1beta, TNFalpha or IL-12 after the in vitro LPS stimulus. At t = 6 h, this LPS-hyporesponsiveness could dose-dependently be inhibited by RWJ-67657 treatment of the volunteers. We therefore conclude that p38 MAP kinase inhibition with RWJ-67657 inhibited monocyte production of cytokines following in vivo LPS injection. Treatment with RWJ-67657 also reversed the LPS-hyporesponsiveness. Whether this result can be extended to the clinical situation remains to be elucidated. Patients with sepsis or an otherwise high risk for multi-organ failure are potential study groups.

Inhibition of interleukin-6-activated janus kinases/signal transducers and activators of transcription but not mitogen-activated protein kinase signaling in liver of endotoxin-treated rats

OBJECTIVES

Endotoxin-induced cytokines, such as interleukin-6, mediate systemic inflammatory responses through multiple cellular signaling pathways. Interleukin-6 is also responsible for the synthesis of acute phase proteins. Recent studies have shown that endotoxin can inhibit signal transducers and activators of transcription (STAT)-3 tyrosine phosphorylation in cultured cells, suggesting that this effect may limit the synthesis of acute phase proteins. The purpose of this study was to examine the effects of endotoxin on interleukin-6 activation of STATs and mitogen-activated protein (MAP) kinase pathways in rat liver in vivo.

DESIGN

Controlled laboratory study.

SETTING

Medical school laboratory.

SUBJECTS

Specific pathogen-free male Sprague Dawley rats.

INTERVENTIONS

Under anesthesia, interleukin-6 was injected into the portal vein of rats 4 hrs after the bolus intravenous administration of endotoxin (1 mg/kg) or saline. The effects of interleukin-6 on key intermediates in early steps of the interleukin-6 signaling pathway, including janus kinase-1, gp 130, the interleukin-6 receptor, STAT1, and STAT3, were examined in both saline and endotoxin-treated rats.

MEASUREMENTS AND MAIN RESULTS

In endotoxin-treated rats, there was significant inhibition of interleukin-6 activation of janus kinase-1, gp 130, the interleukin-6 receptor, STAT1, and STAT3. These signaling changes were associated with decreased tissue abundance of interleukin-6 receptors and STAT3. In contrast to its effects on the janus kinase/STAT pathways, interleukin-6 activation of MAP kinases (extracellular signal-regulated kinase-1, extracellular signal-regulated kinase-2, and p38) was unaffected by endotoxin.

CONCLUSIONS

The pathway-specific inhibition of interleukin-6 signaling responses in the liver may be an important determinant of the pathophysiologic consequences of endotoxin exposure.

Peritonitis induces rat cardiac myocytes to promote polymorphonuclear leukocyte emigration and activate endothelial cells: effect of lipopolysaccharide pretreatment

OBJECTIVE

Peritonitis induced by cecal ligation and perforation results in inflammation and dysfunction of the rat myocardium, an organ remote from the locus of infection. This peritonitis-induced pathology can be prevented by pretreating these animals with lipopolysaccharide before cecal ligation and perforation. In the present study, we assessed a) whether cardiomyocytes obtained from rats subjected to cecal ligation and perforation could induce polymorphonuclear leukocyte transendothelial migration, b) whether these cardiomyocytes could activate endothelial cells (increased proadhesive phenotype), and c) whether these responses could be attenuated by lipopolysaccharide pretreatment.

DESIGN

Prospective animal study.

SETTING

Experimental animal laboratory.

SUBJECTS

Male Sprague Dawley rats.

INTERVENTIONS

Lipopolysaccharide pretreated and nonpretreated rats were subjected to cecal ligation and perforation or to laparotomy. Myocytes were isolated 6 hrs after surgery and used for in vitro experiments.

MEASUREMENTS AND MAIN RESULTS

Myocytes isolated from cecal ligation and perforation rats promoted migration of polymorphonuclear leukocytes across a rat endothelial cell monolayer, an effect prevented by platelet activating factor receptor antagonists. Myocytes isolated from these animals also increased surface level expression of intercellular adhesion molecule-1 on rat endothelial cells, an effect also prevented by platelet activating factor receptor antagonists. Myocytes isolated from rats pretreated with lipopolysaccharide and then subjected to cecal ligation and perforation did not a) promote polymorphonuclear leukocyte transendothelial migration or b) increase intercellular adhesion molecule-1 surface expression on endothelial cells.

CONCLUSIONS

Our findings indicate that induction of peritonitis results in a systemic response that induces cardiac myocytes to become proinflammatory (i.e., these myocytes produce chemotactic factors and activate endothelial cells). This effect of cecal ligation and perforation is abrogated by pretreating animals with lipopolysaccharide before induction of peritonitis.