Soluble vascular endothelial growth factor receptor-1 protects mice in sepsis

Clinical value of soluble fms-like tyrosine kinase 1 (sFlt-1) in adult secondary hemophagocytic lymphohistiocytosis

BACKGROUND

Secondary hemophagocytic lymphohistiocytosis (sHLH) is a syndrome characterized by an excessive systemic inflammatory response, manifested by multiple organ dysfunction, lacking reliable immune biomarkers for predicting their inflammatory status and prognosis. Soluble fms-like tyrosine kinase 1 (sFlt-1) is associated with various inflammation-related diseases, including sepsis and severe organ failure.

METHODS

This study retrospectively included 32 adult sHLH patients diagnosed from January 2020 to December 2021. The expression of Flt-1 in peripheral blood CD14 + monocytes was detected by flow cytometry, and the level of plasma sFlt-1 was detected by ELISA.

RESULTS

In our study, the results of flow cytometry reveal that the Flt-1 expression on CD14 + monocytes of peripheral blood from sHLH patients was higher than that in normal control. In plasma samples of sHLH patients, sFlt-1 levels were 677.8 (463.2-929.7) pg/mL, significantly higher than in normal controls 377.18 (350.4-424.6) pg/mL and sepsis group 378.3 (257.0-499.1) pg/mL. Besides, a positive correlation was found between sFlt-1 and IL-6 in sHLH patients. The analysis of univariate Cox regression indicated that sFlt-1 >681.5 pg/mL demonstrated unfavorable overall survival ( p = 0.022). Multivariate analysis demonstrated that sFlt-1 >681.5 pg/mL was an independent factor associated with OS ( p = 0.041) after adjustment for confounders. Restricted cubic spline confirmed a linear and positive association between sFlt-1 and mortality risk.

CONCLUSION

Retrospective analysis showed that sFlt-1 was a promising prognostic factor.

The VEGF Inhibitor Soluble Fms-like Tyrosine Kinase 1 Does Not Promote AKI-to-CKD Transition

(1) Background: Soluble Fms-like tyrosine kinase 1 (sFLT1) is an endogenous VEGF inhibitor. sFLT1 has been described as an anti-inflammatory treatment for diabetic nephropathy and heart fibrosis. However, sFLT1 has also been related to peritubular capillary (PTC) loss, which promotes fibrogenesis. Here, we studied whether transfection with sFlt1 aggravates experimental AKI-to-CKD transition and whether sFLT1 is increased in human kidney fibrosis. (2) Methods: Mice were transfected via electroporation with sFlt1. After confirming transfection efficacy, mice underwent unilateral ischemia/reperfusion injury (IRI) and were sacrificed 28 days later. Kidney histology and RNA were analyzed to study renal fibrosis, PTC damage and inflammation. Renal sFLT1 mRNA expression was measured in CKD biopsies and control kidney tissue. (3) Results: sFlt1 transfection did not aggravate renal fibrosis, PTC loss or macrophage recruitment in IRI mice. In contrast, higher transfection efficiency was correlated with reduced expression of pro-fibrotic and pro-inflammatory markers. In the human samples, sFLT1 mRNA levels were similar in CKD and control kidneys and were not correlated with interstitial fibrosis or PTC loss. (4) Conclusion: As we previously found that sFLT1 has therapeutic potential in diabetic nephropathy, our findings indicate that sFLT1 can be administered at a dose that is therapeutically effective in reducing inflammation, without promoting maladaptive kidney damage.

Combined glucocorticoid resistance and hyperlactatemia contributes to lethal shock in sepsis

Sepsis is a potentially lethal syndrome resulting from a maladaptive response to infection. Upon infection, glucocorticoids are produced as a part of the compensatory response to tolerate sepsis. This tolerance is, however, mitigated in sepsis due to a quickly induced glucocorticoid resistance at the level of the glucocorticoid receptor. Here, we show that defects in the glucocorticoid receptor signaling pathway aggravate sepsis pathophysiology by lowering lactate clearance and sensitizing mice to lactate-induced toxicity. The latter is exerted via an uncontrolled production of vascular endothelial growth factor, resulting in vascular leakage and collapse with severe hypotension, organ damage, and death, all being typical features of a lethal form of sepsis. In conclusion, sepsis leads to glucocorticoid receptor failure and hyperlactatemia, which collectively leads to a lethal vascular collapse.

[The indicators of basal metabolism in inflammatory syndrome bacterial origin: predictors of prognosis or the need for timely correction?]

The aim of the study was to determine the comparative significance of basal metabolism indicators and inflammatory process markers for the closest prognosis of patients in ICUs with systemic inflammation syndrome caused with infectious genesis. The paper presents the results of a retrospective analysis of the plan of treatment of 198 patients with confirmed clinical and laboratory signs of bacterial infection. The number of leukocytes, platelets, the percentage of lymphocytes, the concentration of procalcitonin, creatinine, bilirubin, C-reactive protein, acid-base balance values were determined in patients. Patients were assessed on a SOFA scale. The type of biomaterial for microbiological research was determined depending on the intended source of infectious inflammation. Identification of the isolated microorganisms was carried out using the MALDI ToF mass spectrometry method, followed by determination of antibiotic resistance. Empirical antibiotic therapy was prescribed upon admission of the patient to the ICU. Patients were switched to etiotropic antibacterial therapy after 48 hours, taking into account the results of a microbiological study. Determination of basal metabolic rate was carried out using the method of indirect calorimetry (CCM Express, Medical Graphics) with the calculation of basal metabolism, respiratory coefficient, absolute and relative amount of macronutrients. The calculation of the protein was made on the basis of the nitrogen level of the daily urine urea. Logistic analysis (ROC analysis) revealed that the antibacterial therapy strategy used, age, gender of patients, tinctorial properties of microorganisms isolated from patients, do not affect the nearest prognosis of the disease. On the contrary, SOFA score, the concentration of procalcitonin in the blood, and such parameters of the metabolic status as the need for kilocalories per kilogram of actual body weight and the percentage of protein calories significantly affect the nearest prognosis of the disease. The percentage of calories derived from protein metabolism, in the main exchange has a high reliable predictive value. The results of the study confirm the importance of adequate nutritional therapy in the treatment of patients with infectious inflammatory syndrome, including the calculation and correction of protein loss and total daily calorie.

Vascular endothelial growth factor increased the permeability of respiratory barrier in acute respiratory distress syndrome model in mice

Background

Acute respiratory distress syndrome is associated with a mortality of 45%. The authors investigated the possible mechanisms and effect of vascular endothelial growth factor on alveolar epithelial barrier permeability in acute respiratory distress syndrome mice model.

Methods

Eighty Male BALB/c mice were randomly assigned to four group: PBS group, LPS group, sFlt group, or LPS + sFlt group. The levels of vascular endothelial growth factor and total protein in bronchoalveolar lavage fluid were compared, together with lung injury score and the histopathology of alveolar epithelial barrier. The expressions of vascular endothelial growth factor and tight junction proteins mRNA in lung tissue were also studied.

Results

Lipopolysaccharide (LPS) inhaling was accompanied with increasing lung vascular endothelial growth factor (VEGF) expression. Anti-VEGF with soluble fms-like tyrosine kinase-1 (sFlt-1) attenuated the lung injury effectively.

Conclusions

Our data indicate that anti-vascular endothelial growth factor with soluble fms-like tyrosine kinase-1 could maintain the normal structure and function of respiratory membrane in acute respiratory distress syndrome mice model and might be a suitable therapeutic tool for the treatment of acute respiratory distress syndrome.

Quantitative measurement of selected protein biomarkers of endothelial dysfunction in plasma by micro-liquid chromatography-tandem mass spectrometry based on stable isotope dilution method

The aim of this study was to develop and validate the novel microLC/MS-MRM method for the simultaneous quantification of six proteins: angiopoietin 2 (Angpt-2), soluble form of fms-like tyrosine kinase 1 (sFLT-1), plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator (t-PA), endocan (ESM-1), soluble form of E-selectin (sE-sel), and one peptide: adrenomedullin (ADM) in mouse plasma. Two approaches were compared: a stable isotope dilution (SID) method- used as a reference and a modified SID (mSID) procedure. In SID strategy the calibration curves were used, whereas in mSID the ratio between the chromatogram peak area of endogenous tryptic peptides at unknown concentration to chromatogram peak area of exogenous, stable isotope-labelled internal standards (SISs) added to the sample at known concentration was calculated. The microLC/MS-MRM method in the SID approach was linear from 0.250 pmol/mL to 250 pmol/mL for Angpt-2; 5 pmol/mL to 5000 pmol/mL for sFLT-1; 2.5 pmol/mL to 5000 pmol/mL for PAI-1; 0.375 pmol/mL to 250 pmol/mL for t-PA; 0.375 pmol/mL to 187.5 pmol/mL for ESM-1; 2.5 pmol/mL to 5000 pmol/mL for sE-sel and 0.375 pmol/mL to 250 pmol/mL for ADM. LPS-induced changes in plasma assessed based on SID and mSID approaches gave comparable quantitative results and featured LPS-induced dysregulation of endothelial permeability (Angpt-2, sFLT-1), glycocalyx injury (SDC-1) accompanied by a pro-thrombotic response (PAI-1). In addition, we applied microLC/MS-MRM method with mSID strategy to analyze human plasma samples from patients with chronic myeloid leukemia (CML) and obstructive sleep apnoea (OSA) and demonstrated usefulness of the method to characterize endothelial function in humans. In conclusion, the microLC/MS-MRM method with mSID strategy applied for simultaneous quantification of protein biomarkers of endothelial function in plasma represents a novel targeted proteomic platform for the comprehensive evaluation of endothelial function in mice and humans.

Soluble Fms-Like Tyrosine Kinase-1 Is A Marker of Endothelial Dysfunction During Sepsis

Background

Sepsis is currently defined as a life-threatening organ dysfunction caused by a deregulated host response to infection. There is increasing evidence that the endothelium plays a crucial and pathogenic role in sepsis. Profound alterations of the endothelium associated with sepsis include increased leucocytes adhesions, shift to a procoagulant state, vasodilatation, altered barrier function with more permeable capillaries and tissue edema. The vascular endothelial growth factor (VEGF) pathway is involved in the control of microvascular permeability and has been involved in the pathogenesis of conditions associated with endothelial barrier disruption such as sepsis. sFlt-1 is a soluble variant of the VEGF receptor (Fms-like tyrosine kinase-1, Flt-1 or VEGFR-1) able to down-regulate the effects of VEGF by decreasing its signaling. We investigated the possible involvement of sFlt-1 as biomarker of endothelial alteration during sepsis, organ dysfunction and death.

Methods

Serum levels of s-Flt1 were measured in 170 hospitalized patients (77 with sepsis, confirmed by positive blood culture), and in 18 healthy volunteers. The sequential organ failure assessment (SOFA) score was determined by using biochemical and clinical parameters. In a small number of patients (9 individuals), s-Flt1 concentration was evaluated after negativization of the blood culture.

Results

Serum level of s-Flt1 was significantly higher in septic patients than blood culture-negative patients (277.7 ± 52.7 and 133.4 ± 12.4 pg/mL, respectively, P = 0.0088), both groups of patients had significantly higher concentration of sFlt-1 than healthy individuals (78.9 ± 2.5 pg/mL). Among sepsis cases, 68% was caused by Gram-negative bacteria, 27% by Gram-positive bacteria and 8% by Candida species. Serum level of s-Flt1 showed a significant difference between Gram-negative (274.1 pg/mL) and Gram-positive (145.7 pg/mL) sepsis. SOFA score (evaluated in 20 patients with sFlt-1 >190 pg/mL) showed a positive trend of correlation with the increasing sFlt-1 level. After blood culture negativization, serum level of sFlt-1 decreased (37%).

Conclusion

Our findings confirm, in a larger population of patients with sepsis, recent evidences that sFlt-1 levels are higher in patients with complicated-sepsis that evolve to septic shock and suggest that sFlt-1 could be a useful biomarker for sepsis severity. An anti-VEGF effect mediated by sFlt-1 could be hypothesized as salvage compensatory mechanism activated in response to sepsis.

Preeclampsia as a Form of Type 5 Cardiorenal Syndrome: An Underrecognized Entity in Women's Cardiovascular Health

BACKGROUND

Preeclampsia is a multisystem vascular disorder of pregnancy that remains a leading cause of maternal and fetal morbidity and mortality. Preeclampsia remains an underrecognized risk factor for future cardiovascular and kidney disease in women and represents the confluence of preexisting vascular risk factors with superimposed endothelial injury from placental mediated anti-angiogenic factors.

SUMMARY

This review highlights the close relationship between preeclampsia and future cardiovascular and kidney disease. It describes the pathophysiology and current understanding of biomarkers that form the molecular signature for long-term endothelial dysfunction in preeclamptic women. Finally, it describes strategies for early identification and management of women with preeclampsia with elevated risk for cardiovascular and kidney disease. Key Messages: Future rigorous studies on cardiovascular risk modification in this phenotype of disease are essential to reduce the burden of cardiovascular and kidney disease, in women with preeclampsia.

Corneal Mesenchymal Stromal Cells Are Directly Antiangiogenic via PEDF and sFLT-1

Purpose

To evaluate the angiogenic properties of corneal derived mesenchymal stromal cells (Co-MSC).

Methods

Co-MSCs were extracted from human cadaver, and wild-type (C57BL/6J) and SERPINF1^−/− mice corneas. The MSC secretome was collected in a serum-free medium. Human umbilical vein endothelial cell (HUVEC) tube formation and fibrin gel bead assay (FIBA) sprout formation were used to assess the angiogenic properties of Co-MSC secretome. Complete corneal epithelial debridement was used to induce corneal neovascularization in wild-type mice. Co-MSCs embedded in fibrin gel was applied over the debrided cornea to evaluate the angiogenic effects of Co-MSCs in vivo. Immunoprecipitation was used to remove soluble fms-like tyrosine kinase-1 (sFLT-1) and pigment epithelium-derived factor (PEDF, SERPINF1 gene) from the Co-MSC secretome.

Results

Co-MSC secretome significantly inhibited HUVECs tube and sprout formation. Co-MSCs from different donors consistently contained high levels of antiangiogenic factors including sFLT-1 and PEDF; and low levels of the angiogenic factor VEGF-A. In vivo, application of Co-MSCs to mouse corneas after injury prevented the development of corneal neovascularization. Removing PEDF or sFLT-1 from the secretome significantly diminished the antiangiogenic effects of Co-MSCs. Co-MSCs isolated from SERPINF1^−/− mice had significantly reduced antiangiogenic effects compared to SERPINF1^+/+ (wild-type) Co-MSCs.

Conclusions

These results illustrate the direct antiangiogenic properties of Co-MSCs, the importance of sFLT-1 and PEDF, and their potential clinical application for preventing pathologic corneal neovascularization.

The VEGF-A inhibitor sFLT-1 improves renal function by reducing endothelial activation and inflammation in a mouse model of type 1 diabetes

AIMS/HYPOTHESIS

Animal models of diabetic nephropathy show increased levels of glomerular vascular endothelial growth factor (VEGF)-A, and several studies have shown that inhibiting VEGF-A in animal models of diabetes can prevent albuminuria and glomerular hypertrophy. However, in those studies, treatment was initiated before the onset of kidney damage. Therefore, the aim of this study was to investigate whether transfecting mice with the VEGF-A inhibitor sFlt-1 (encoding soluble fms-related tyrosine kinase 1) can reverse pre-existing kidney damage in a mouse model of type 1 diabetes. In addition, we investigated whether transfection with sFlt-1 can reduce endothelial activation and inflammation in these mice.

METHODS

Subgroups of untreated 8-week-old female C57BL/6J control (n = 5) and diabetic mice (n = 7) were euthanised 5 weeks after the start of the experiment in order to determine the degree of kidney damage prior to treatment with sFLT-1. Diabetes was induced with three i.p. injections of streptozotocin (75 mg/kg) administered at 2 day intervals. Diabetic nephropathy was then investigated in diabetic mice transfected with sFlt-1 (n = 6); non-diabetic, non-transfected control mice (n = 5); non-diabetic control mice transfected with sFlt-1(n = 10); and non-transfected diabetic mice (n = 6). These mice were euthanised at the end of week 15. Transfection with sFlt-1 was performed in week 6.

RESULTS

We found that transfection with sFlt-1 significantly reduced kidney damage by normalising albuminuria, glomerular hypertrophy and mesangial matrix content (i.e. glomerular collagen type IV protein levels) (p < 0.001). We also found that transfection with sFlt-1 reduced endothelial activation (p < 0.001), glomerular macrophage infiltration (p < 0.001) and glomerular TNF-α protein levels (p < 0.001). Finally, sFLT-1 decreased VEGF-A-induced endothelial activation in vitro (p < 0.001).

CONCLUSIONS/INTERPRETATION

These results suggest that sFLT-1 might be beneficial in treating diabetic nephropathy by inhibiting VEGF-A, thereby reducing endothelial activation and glomerular inflammation, and ultimately reversing kidney damage.

Validation of two multiplex platforms to quantify circulating markers of inflammation and endothelial injury in severe infection

Biomarkers can prognosticate outcome and enable risk-stratification. In severe infection, focusing on multiple markers reflecting pathophysiological mechanisms of organ injury could enhance management and pathway-directed therapeutics. Limited data exist on the performance of multiplex biomarker platforms. Our goal was to compare endothelial and immune activation biomarkers in severe pediatric infections using two multiplex platforms. Frozen plasma from 410 children presenting to the Jinja Regional Hospital in Uganda with suspected infection was used to measure biomarkers of endothelial (Angiopoietin-2, sFlt-1, sVCAM-1, sICAM-1) and immune (IL-6, IP-10, sTNFR-1, CHI3L1) activation. Two multiplex platforms (Luminex®, Ella^TM) based on monoclonal antibody sandwich immunoassays using biotin-streptavidin conjugate chemistry were selected with reagents from R&D Systems. The two platforms differed in ease and time of completion, number of samples per assay, and dynamic concentration range. Intra-assay variability assessed using a coefficient of variation (CV%) was 2.2–3.4 for Luminex® and 1.2–2.9 for Ella^TM. Correlations for biomarker concentrations within dynamic range of both platforms were best for IL-6 (ρ = 0.96, p<0.0001), IP-10 (ρ = 0.94, p<0.0001) and sFlt-1 (ρ = 0.94, p<0.0001). Agreement between concentrations obtained by both methods assessed by the Bland-Altman test varied, with best agreement for CHI3L1. Our data suggest that biomarkers of endothelial and immune activation can be readily measured with multiplex platforms. Luminex® and Ella^TM produced reliable results with excellent CV% values. The Ella^TM platform was more automated and completed in 75 minutes, potentially compatible with near-patient use. Trends in concentrations obtained by these methods were highly correlated, although absolute values varied, suggesting caution is required when comparing data from different multiplex platforms.

Splice Variants of the RTK Family: Their Role in Tumour Progression and Response to Targeted Therapy

Receptor tyrosine kinases (RTKs) belong to a family of transmembrane receptors that display tyrosine kinase activity and trigger the activation of downstream signalling pathways mainly involved in cell proliferation and survival. RTK amplification or somatic mutations leading to their constitutive activation and oncogenic properties have been reported in various tumour types. Numerous RTK-targeted therapies have been developed to counteract this hyperactivation. Alternative splicing of pre-mRNA has recently emerged as an important contributor to cancer development and tumour maintenance. Interestingly, RTKs are alternatively spliced. However, the biological functions of RTK splice variants, as well as the upstream signals that control their expression in tumours, remain to be understood. More importantly, it remains to be determined whether, and how, these splicing events may affect the response of tumour cells to RTK-targeted therapies, and inversely, whether these therapies may impact these splicing events. In this review, we will discuss the role of alternative splicing of RTKs in tumour progression and response to therapies, with a special focus on two major RTKs that control proliferation, survival, and angiogenesis, namely, epidermal growth factor receptor (EGFR) and vascular endothelial growth factor receptor-1 (VEGFR1).

Autodigestion: Proteolytic Degradation and Multiple Organ Failure in Shock

There is currently no effective treatment for multiorgan failure following shock other than supportive care. A better understanding of the pathogenesis of these sequelae to shock is required. The intestine plays a central role in multiorgan failure. It was previously suggested that bacteria and their toxins are responsible for the organ failure seen in circulatory shock, but clinical trials in septic patients have not confirmed this hypothesis. Instead, we review here evidence that the digestive enzymes, synthesized in the pancreas and discharged into the small intestine as requirement for normal digestion, may play a role in multiorgan failure. These powerful enzymes are nonspecific, highly concentrated, and fully activated in the lumen of the intestine. During normal digestion they are compartmentalized in the lumen of the intestine by the mucosal epithelial barrier. However, if this barrier becomes permeable, e.g. in an ischemic state, the digestive enzymes escape into the wall of the intestine. They digest tissues in the mucosa and generate small molecular weight cytotoxic fragments such as unbound free fatty acids. Digestive enzymes may also escape into the systemic circulation and activate other degrading proteases. These proteases have the ability to clip the ectodomain of surface receptors and compromise their function, for example cleaving the insulin receptor causing insulin resistance. The combination of digestive enzymes and cytotoxic fragments leaking into the central circulation causes cell and organ dysfunction, and ultimately may lead to complete organ failure and death. We summarize current evidence suggesting that enteral blockade of digestive enzymes inside the lumen of the intestine may serve to reduce acute cell and organ damage and improve survival in experimental shock.

The effects of 22°C and 4°C storage of platelets on vascular endothelial integrity and function

BACKGROUND

Although a majority of the studies conducted to date on platelet (PLT) storage have been focused on PLT hemostatic function, the effects of 4°C PLTs on regulation of endothelial barrier permeability are still not known. In this study, we compared the effects of room temperature (22°C) stored and (4°C) stored PLTs on the regulation of vascular endothelial cell (EC) permeability in vitro and in vivo.

STUDY DESIGN AND METHODS

Day 1, Day 5, and Day 7 leukoreduced apheresis PLTs stored at 4 or 22°C were studied in vitro and in vivo. In vitro, PLT effects on EC permeability and barrier function, adhesion, and impedance aggregometry were investigated. In vivo, using a mouse model of vascular leak, attenuation of vascular leak and circulating PLT numbers were measured.

RESULTS

Treatment of EC monolayers with Day 5 or Day 7 PLTs, stored at both 22°C and 4°C, resulted in similar decreases in EC permeability on average. However, analysis of individual samples revealed significant variation that was donor dependent. Additional in vitro measurements revealed a decrease in inflammatory mediators, nonspecific PLT-endothelial aggregation and attenuated loss of aggregation over time to TRAP, ASPI, ADP, and collagen with 4°C storage. In mice, while 22°C and 4°C PLTs both demonstrated significant protection against vascular endothelial growth factor A (VEGF-A)-induced vascular leak 22°C PLTs exhibited increased protection compared to 4°C PLTs. Systemic circulating levels of 4°C PLTs were decreased compared to 22°C PLTs.

CONCLUSIONS

In vitro, 4°C-stored PLTs exhibit a greater capacity to inhibit EC permeability than 22°C-stored PLTs. In vivo, 22°C PLTs provide superior control of vascular leak induced by VEGF-A. This discrepancy may be due to increased clearance of 4°C PLTs from the systemic circulation.

Dynamic macrophage polarization-specific miRNA patterns reveal increased soluble VEGF receptor 1 by miR-125a-5p inhibition

Dynamic, epigenetic mechanisms can regulate macrophage phenotypes following exposure to different stimulating conditions and environments. However, temporal patterns of microRNAs (miRNAs or miRs) across multiple macrophage polarization phenotypes have not been defined. We determined miRNA expression in bone marrow-derived murine macrophages over multiple time points (0.5, 1, 3, 24 h) following exposure to cytokines and/or LPS. We hypothesized that dynamic changes in miRNAs regulate macrophage phenotypes. Changes in macrophage polarization markers were detected as early as 0.5 and as late as 24 h; however, robust responses for most markers occurred within 3 h. In parallel, many polarization-specific miRNAs were also changed by 3 h and expressed divergent patterns between M1 and M2a conditions, with increased expression in M1 (miR-155, 199a-3p, 214-3p, 455-3p, and 125a) or M2a (miR-511 and 449a). Specifically, miR-125a-5p exhibited divergent patterns: increased at 12-24 h in M1 macrophages and decreasing trend in M2a. VEGF in the culture media of macrophages was dependent upon the polarization state, with greatly diminished VEGF in M2a compared with M1 macrophage culture media despite similar VEGF in cell lysates. Inhibition of miR-125a-5p in media-only controls (MO) and M1 macrophages greatly increased expression and secretion of soluble VEGF receptor-1 (sVEGFR1) leading to diminished VEGF in the culture media, partially converting MO and M1 into an M2a phenotype. Thus, the divergent expression patterns of polarization-specific miRNAs led to the identification and demonstrated the regulation of a specific macrophage polarization phenotype, sVEGFR1 by inhibition of miR-125a-5p.

Microparticles: markers and mediators of sepsis-induced microvascular dysfunction, immunosuppression, and AKI

Sepsis is a severe and complex syndrome that lacks effective prevention or therapeutics. The effects of sepsis on the microvasculature have become an attractive area for possible new targets and therapeutics. Microparticles (MPs) are cell membrane-derived particles that can promote coagulation, inflammation, and angiogenesis, and they can participate in cell-to-cell communication. MPs retain cell membrane and cytoplasmic constituents of their parental cells, including two procoagulants: phosphatidylserine and tissue factor. We highlight the role of microparticles released by endothelial and circulating cells after sepsis-induced microvascular injury, and we discuss possible mechanisms by which microparticles can contribute to endothelial dysfunction, immunosuppression, and multiorgan dysfunction--including sepsis-AKI. Once viewed as cellular byproducts, microparticles are emerging as a new class of markers and mediators in the pathogenesis of sepsis.

Endocan, a putative endothelial cell marker, is elevated in preeclampsia, decreased in acute pyelonephritis, and unchanged in other obstetrical syndromes

Objective: Endocan, a dermatan sulphate proteoglycan produced by endothelial cells, is considered a biomarker for endothelial cell activation/dysfunction. Preeclampsia is characterized by systemic vascular inflammation, and endothelial cell activation/dysfunction. Therefore, the objectives of this study were to determine whether: (1) plasma endocan concentrations in preeclampsia differ from those in uncomplicated pregnancies; (2) changes in plasma endocan concentration relate to the severity of preeclampsia, and whether these changes are specific or observed in other obstetrical syndromes such as small-for-gestational age (SGA), fetal death (FD), preterm labor (PTL) or preterm prelabor rupture of membranes (PROM); (3) a correlation exists between plasma concentration of endocan and angiogenic (placental growth factor or PlGF)/anti-angiogenic factors (soluble vascular endothelial growth factor receptor or sVEGFR-1, and soluble endoglin or sEng) among pregnancies complicated by preeclampsia; and (4) plasma endocan concentrations in patients with preeclampsia and acute pyelonephritis (both conditions in which there is endothelial cell activation) differ.

Method: This cross-sectional study included the following groups: (1) uncomplicated pregnancy (n = 130); (2) preeclampsia (n = 102); (3) pregnant women without preeclampsia who delivered an SGA neonate (n = 51); (4) FD (n = 49); (5) acute pyelonephritis (AP; n = 35); (6) spontaneous PTL (n = 75); and (7) preterm PROM (n = 64). Plasma endocan concentrations were determined in all groups, and PIGF, sEng and VEGFR-1 plasma concentrations were measured by ELISA in the preeclampsia group.

Results: (1) Women with preeclampsia had a significantly higher median plasma endocan concentration than those with uncomplicated pregnancies (p = 0.004); (2) among women with preeclampsia, the median plasma endocan concentration did not differ significantly according to disease severity (p = 0.1), abnormal uterine artery Doppler velocimetry (p = 0.7) or whether diagnosis was made before or after 34 weeks gestational age (p = 0.3); (3) plasma endocan concentration in women with preeclampsia correlated positively with plasma anti-angiogenic factor concentrations [sVEGFR-1: Spearman rho 0.34, p = 0.001 and sEng: Spearman rho 0.30, p = 0.003]; (4) pregnancies complicated by acute pyelonephritis with bacteremia had a lower median plasma endocan concentration than pregnancies complicated by acute pyelonephritis without bacteremia (p = 0.004), as well as uncomplicated pregnancies (p = 0.001); and (5) there was no significant difference in the median plasma endocan concentration between uncomplicated pregnancies and those complicated by FD, delivery of an SGA neonate, PTL or preterm PROM (other members of the “great obstetrical syndromes”; each p > 0.05).

Conclusion: Median maternal plasma endocan concentrations were higher preeclampsia and lower in acute pyelonephritis with bacteremia than in uncomplicated pregnancy. No significant difference was observed in the median plasma endocan concentration between other great obstetrical syndromes and uncomplicated pregnancies. The difference in the direction of change of endocan in preeclampsia and acute pyelonephritis with bacteremia may be consistent with the view that both disease entities differ in pathogenic mechanisms, despite their associations with systemic vascular inflammation and endothelial cell activation/dysfunction.

A comparison of adipose and bone marrow-derived mesenchymal stromal cell secreted factors in the treatment of systemic inflammation

BACKGROUND

Bone marrow-derived mesenchymal stromal cells (BMSCs) are a cell population of intense exploration for therapeutic use in inflammatory diseases. Secreted factors released by BMSCs are responsible for the resolution of inflammation in several pre-clinical models. New studies have uncovered that adipose tissue also serves as a reservoir of multipotent, non-hematopoietic stem cells, termed adipose-derived stromal/stem cells (ASCs), with many common characteristics to BMSCs. We hypothesized that ASC and BMSC secreted factors would lead to a comparable benefit in the context of generalized inflammation.

FINDINGS

Proteomic profiling of conditioned media revealed that BMSCs express significantly higher levels of sVEGFR1 and sTNFR1, two soluble cytokine receptors with known therapeutic activity in sepsis. In a prophylactic study of endotoxin-induced inflammation in mice, we observed that BMSC secreted factors provided a greater survival benefit and tissue protection of endotoxemic mice compared to ASCs. Neutralization of sVEGFR1 and sTNFR1 did not significantly affect the survival benefit experienced by mice treated with BMSC secreted factors.

CONCLUSIONS

Our findings suggest that BMSCs may be more effective as a cell therapeutic for use in endotoxic shock and that ASCs may be positioned for continued exploration in immunomodulatory diseases. Soluble cytokine receptors can distinguish stromal cells from different tissue origins, though they may not be the sole contributors to the therapeutic benefit of BMSCs. Furthermore, other secreted factors not discussed in this study may also differentiate these stromal cell populations from one another.

Biomarkers of endothelial cell activation in early sepsis

PURPOSE

The objective of this study was to investigate the association of endothelial-related markers with organ dysfunction and in-hospital mortality to validate our earlier findings in a multicenter study. We hypothesize that (i) endothelial biomarkers will be associated with organ dysfunction and mortality in sepsis and that (ii) soluble fms-like tyrosine kinase 1 (sFlt-1) holds promise as a novel prognostic marker in sepsis.

METHODS

This was a prospective, multicenter, observational study of a convenience sample of emergency department (ED) patients with a suspected infection presenting to one of four urban, academic medical center EDs between January 2009 and January 2010. We collected plasma while the patients were in the ED and subsequently assayed endothelial-related biomarkers, namely, sFlt-1, soluble E-selectin, soluble intercellular adhesion molecule 1, soluble vascular cell adhesion molecule 1, and plasminogen activator inhibitor 1 (PAI-1). Outcomes were organ dysfunction and in-hospital mortality.

RESULTS

We enrolled a total of 166 patients: 63 with sepsis (38%), 61 with severe sepsis (37%), and 42 with septic shock (25%). All endothelial biomarkers were significantly associated with sepsis severity, P < 0.002. We found a significant intercorrelation between all biomarkers, strongest between sFlt-1 and PAI-1 (r = 0.61, P < 0.001) and PAI-1 and soluble E-selectin and soluble intercellular adhesion molecule 1 (r = 0.49, P < 0.001). Among the endothelial biomarkers, sFlt-1 had the strongest association with Sequential Organ Failure Assessment score (r = 0.58, P < 0.001). Soluble fms-like tyrosine kinase 1 and PAI-1 had the highest area under the operating receiver characteristic curve for mortality of 0.87.

CONCLUSIONS

This multicenter validation study confirms that markers of endothelial activation are associated with sepsis severity, organ dysfunction, and mortality in sepsis. This supports the hypothesis that the endothelium plays a central role in the pathophysiology of sepsis and may serve as a more accurate prediction tool and a target for therapies aimed at ameliorating endothelial cell dysfunction. In addition, sFLT-1 holds promise as a novel sepsis severity biomarker.

Decreased expression of serum and microvascular vascular endothelial growth factor receptor-2 in meningococcal sepsis*

OBJECTIVES

To determine the skin microvessel expression of vascular endothelial growth factor receptor 2 and serum-soluble vascular endothelial growth factor receptor 2 levels in children with meningococcal sepsis.

DESIGN

Observational study.

SETTING

Two tertiary academic children hospital PICUs.

PATIENTS

Children with meningococcal sepsis.

INTERVENTION

Skin biopsy and blood sample collection.

MEASUREMENTS AND MAIN RESULTS

Determination of skin microvessel vascular endothelial growth factor receptor 2 expression in skin biopsies by immunohistochemistry and measurement of serum-soluble vascular endothelial growth factor receptor 2 by enzyme-linked immunosorbent assay. Percentage of vascular endothelial growth factor receptor 2-positive skin microvessels and the staining intensity were significantly lower in children with meningococcal sepsis (n = 10) compared to controls (7.6% ± 8.8% vs 44.6% ± 39.2%; p = 0.009 and 0.7% ± 0.7% vs 1.7% ± 1.1%; p = 0.033, respectively). In addition, circulating serum levels of soluble vascular endothelial growth factor receptor 2 were decreased in sepsis (8,148 ± 1,140 pg/mL vs 13,414 ± 2,692 pg/mL; p < 0.001). Serum-soluble vascular endothelial growth factor receptor 2 levels (n = 28) were inversely correlated with Pediatric Risk of Mortality III score (r = -0.43; p = 0.023) and more decreased in nonsurvivors compared to survivors (5,640 ± 1,940 pg/mL vs 7,378 ± 2,336 pg/mL; p = 0.037).

CONCLUSIONS

Microvascular expression of vascular endothelial growth factor receptor 2 and serum-soluble vascular endothelial growth factor receptor 2 levels are decreased in children with sepsis. Serum-soluble vascular endothelial growth factor receptor 2 levels are inversely correlated with disease severity indicated by Pediatric Risk of Mortality III score and survival. Decreased vascular endothelial growth factor receptor 2 expression may hinder natural recovery from sepsis-associated microvascular injury and the effectiveness of therapeutic strategies targeting vascular endothelial growth factor-vascular endothelial growth factor receptor 2 signaling in sepsis patients.

The dynamics of angiogenic factors and their soluble receptors in relation to organ dysfunction in disseminated intravascular coagulation associated with sepsis

We prospectively studied (1) the relationships between angiogenic factors, their soluble receptors and organ dysfunction and (2) the effects of disseminated intravascular coagulation (DIC)-induced platelet consumption, thrombin generation, and tissue hypoxia on the expression of the factors and receptors. Fifty patients with sepsis were classified into two subgroups: 37 patients with DIC and 13 patients without DIC. DIC patients showed higher Sequential Organ Failure Assessment (SOFA) scores, the prevalence of multiple organ dysfunction syndrome (MODS) and more increased soluble fibrin and lactate levels. We observed lower levels of vascular endothelial growth factor (VEGF), soluble VEGF receptor 2 (sVEGFR2), angiopoietin 1 (Ang1) and Ang1/Ang2, and higher sVEGFR1 and Ang2 levels in DIC patients, but not significant differences in soluble Tie2 expression during the study period. The levels of VEGF, sVEGFR1, and Ang2 in DIC patients correlated with the SOFA scores. Clear differences were observed in the levels of Ang2 in the DIC patients between survivors and nonsurvivors and between those with and without MODS. The area under receiver operating characteristic curves for predicting death and MODS by Ang2 were 0.710 and 0.784, respectively. The VEGF levels showed a marked correlation with the platelet counts. Soluble fibrin and lactate levels independently predicted increases in the levels of VEGF, sVEGFR1, and Ang2 in DIC patients. In conclusion, VEGF, sVEGFR1, Ang2, and Ang1/Ang2, especially Ang2, may have roles in the development of MODS in sepsis associated with DIC, and VEGF, sVEGFR1, and Ang2 serum levels correlated with the extent of DIC-induced platelet consumption, thrombin generation, and blood lactate levels.

Flt-1 in colorectal cancer cells is required for the tumor invasive effect of placental growth factor through a p38-MMP9 pathway

Background

Placenta growth factor (PlGF), a dimeric glycoprotein with 53% homology to VEGF, binds to VEGF receptor-1 (Flt-1), but not to VEGF receptor-2 (Flk-1), and may function by modulating VEGF activity. We previously have showed that PlGF displays prognostic value in colorectal cancer (CRC) but the mechanism remains elucidated.

Results

Overexpression of PlGF increased the invasive/migration ability and decreased apoptosis in CRC cells showing Flt-1 expression. Increased migration was associated with increasing MMP9 via p38 MAPK activation. Tumors grew faster, larger; with higher vascularity from PlGF over-expression cells in xenograft assay. In two independent human CRC tissue cohorts, PlGF, MMP9, and Flt-1 expressions were higher in the advanced than the localized disease group. PlGF expression correlated with MMP9, and Flt-1 expression. CRC patients with high PlGF and high Flt-1 expression in tissue had poor prognosis.

Conclusion

PlGF/Flt-1 signaling plays an important role in CRC progression, blocking PlGF/Flt-1 signaling maybe an alternative therapy for CRC.

Peptides modeled on the RGG domain of AUF1/hnRNP-D regulate 3' UTR-dependent gene expression

Messenger RNA binding proteins control post-transcriptional gene expression of targeted mRNAs. The RGG (arginine-glycine-glycine) domain of the AUF1/hnRNP-D mRNA binding protein is a regulatory region that is essential for protein function. The AUF1-RGG peptide, modeled on the RGG domain of AUF1, represses expression of the macrophage cytokine, VEGF. This report expands studies on the AUF1-RGG peptide and evaluates the role of post-translational modifications of the AUF1 protein. Results show that a minimal 31-amino acid AUF1-RGG peptide that lacks poly-glutamine and nuclear localization motifs retains suppressive activity on a VEGF-3'UTR reporter. Arginine residues in RGG motifs may be methylated with resulting changes in protein function. Mass spectroscopy analysis was performed on AUF1 expressed in RAW-264.7 cells. In resting cells, arginines in the first and second RGG motifs are monomethylated. Following activation with lipopolysaccharide, the arginines are dimethylated. To evaluate if the arginine residues are essential for AUF1-RGG activity, the methylatable arginines in the AUF1-3RGG peptide were mutated to lysine or alanine. The R→K and R→A mutants lack activity. We also demonstrate that PI3K/AKT inhibitors reduce VEGF gene expression. Although immunoscreening of AUF1 suggests that LPS and PI3K inhibitors alter the phosphorylation status of AUF1-p37, mass spectroscopy results show that the p37 AUF1 isoform is not phosphorylated with or without lipopolysaccharide stimulation. In summary, arginines in the RGG domain of AUF1 are methylated, and AUF1-RGG peptides may be novel reagents that reduce macrophage activation in inflammation.

Anti-vascular endothelial growth factor antibody attenuates inflammation and decreases mortality in an experimental model of severe sepsis

Introduction

Severe sepsis is associated with an unacceptably high rate of mortality. Recent studies revealed elevated levels of vascular endothelial growth factor (VEGF), a potent angiogenic and vascular permeability factor, in patients with sepsis. There was also an association between VEGF levels and sepsis severity. Here we investigate the effects of an anti-VEGF antibody (Bevacizumab, Bev) in an experimental model of sepsis.

Methods

Human umbilical vein endothelial cells (HUVECs), murine cecal ligation and puncture (CLP), and endotoxemia models of sepsis were used. HUVECs were treated with lipopolysaccharide (LPS) and/or Bev, harvested and cytokine mRNA levels determined using a semi-quantitative reverse transcription-polymerase chain reaction assay. The levels of inflammatory cytokine were also determined in HUVECs supernatants. In addition, the effects of Bev on mortality in the CLP and endotoxemia models of sepsis were evaluated.

Results

Treatment with Bev and LPS significantly decreased the expression and the level of inflammatory cytokines in HUVECs relative to LPS alone. In CLP and endotoxemia models, survival benefits were evident in mice given 0.1 mg/kg of Bev relative to the CLP or LPS alone (P <0.001 and P = 0.028, respectively), and in 6 h post-treated mice relative to the CLP alone for the effect of different time of Bev (P = 0.033). In addition, Bev treatment inhibited LPS-induced vascular leak in the lung, spleen and kidney in the murine endotoxemia model (P <0.05).

Conclusions

Anti-VEGF antibody may be a promising therapeutic agent due to its beneficial effects on the survival of sepsis by decreasing inflammatory responses and endothelial permeability.

Chronic kidney disease worsens sepsis and sepsis-induced acute kidney injury by releasing High Mobility Group Box Protein-1

We have shown that folate-induced kidney dysfunction and interstitial fibrosis predisposes mice to sepsis mortality. Agents that increase survival in normal septic mice were ineffective in a two-stage kidney disease model. Here we used the 5/6 nephrectomy mouse model of progressive chronic kidney disease (CKD) to study how CKD affects acute kidney injury (AKI) induced by sepsis. We induced sepsis using cecal ligation and puncture and found that the presence of CKD intensified the severity of kidney and liver injury, cytokine release, and splenic apoptosis. Accumulation of High Mobility Group Box Protein-1 (HMGB1; a late proinflammatory cytokine released from apoptotic cells), vascular endothelial growth factor (VEGF), tumor necrosis factor (TNF)-α, interleukin (IL)-6, or IL-10 was increased in CKD or sepsis alone and to a greater extent in CKD-sepsis. Only part of the increase was explained by decreased renal clearance. Surprisingly, we found splenic apoptosis in CKD, even in the absence of sepsis. Although VEGF neutralization with soluble fms-like tyrosine kinase 1 (sFLT-1) (a soluble VEGF receptor) effectively treated sepsis, it was ineffective against CKD-sepsis. A single dose of HMGB1-neutralizing antiserum administered 6 h after sepsis alone was ineffective; however, CKD-sepsis was attenuated by anti-HMGB1. Splenectomy transiently decreased circulating HMGB1 levels, reversing the effectiveness of anti-HMGB1 treatment on CKD-sepsis. Thus, progressive CKD increases the severity of sepsis, in part, by reducing the renal clearance of several cytokines. CKD-induced splenic apoptosis and HMGB1 release could be important common mediators for both CKD and sepsis.

A Src family kinase inhibitor improves survival in experimental acute liver failure associated with elevated cerebral and circulating vascular endothelial growth factor levels

BACKGROUND AND AIMS

Acute liver failure (ALF) is frequently complicated by cerebral oedema, systemic inflammation and multiorgan dysfunction. Vascular endothelial growth factor (VEGF) may stimulate liver regeneration but it can also be pro-inflammatory, activating endothelial cells and increasing permeability, actions mediated through Src kinase signalling. We therefore examined whether a Src inhibitor could have therapeutic potential in ALF.

METHODS

Murine ALF was induced with azoxymethane. Liver pathology was graded by a blinded examiner and apoptosis quantified by immunohistochemistry. Cerebral VEGF expression was imaged using VEGF-green fluorescent protein transgenic mice. Circulating and macrophage-secreted VEGF levels were measured. Experimental animals received a Src inhibitor or vehicle controls.

RESULTS

VEGF was undetectable in normal plasma but reached a mean of 835 pg/ml at grade III encephalopathy (P<0.001). Ammonia, lipopolysaccharide and interferon-gamma acted synergistically to enhance VEGF secretion by macrophages. Production of VEGF by cerebral cortical astrocytes increased with disease progression. Late treatment with inhibitors of Src or VEGF did not improve liver histology, encephalopathy or survival. However, early use of a Src kinase inhibitor significantly reduced hepatic injury, delayed encephalopathy and allowed 25% of mice to survive an otherwise lethal insult.

CONCLUSION

Systemic and cerebral VEGF levels are significantly elevated during experimental ALF and may be exacerbated by hyperammonemia and macrophage activation. Early use of a Src inhibitor reduced hepatocellular injury and enabled survival, indicating such agents may have some promise in the treatment of ALF.

Lipopolysaccharide-induced Notch signaling activation through JNK-dependent pathway regulates inflammatory response

BACKGROUND

Notch and TLR pathways were found to act cooperatively to activate Notch target genes and to increase the production of TLR-induced cytokines in macrophages. However, the mechanism of LPS-induced Notch activation and its role in sepsis still remains unclear.

METHODS

We analyzed the expression patterns of Notch components in a LPS-stimulated murine macrophage cell line using real-time PCR and western blotting. The role of DAPT, a gamma-secretase inhibitor that is known to be a potent Notch inhibitor, in LPS-induced cytokine release and experimental sepsis in mice was also explored. Student's t-test was used to analyze the difference between the two groups.

RESULTS

We found that Notch signaling was activated after LPS stimulation. The expression of Jagged 1, a Notch ligand, induced by LPS occurred in a JNK-dependent manner. In addition, Notch target genes were upregulated by early Notch-independent activation followed by delayed Notch-dependent activation after LPS stimulation. Disruption of Notch signaling by DAPT attenuated the LPS-induced inflammatory responses, including vascular endothelial growth factor (VEGF) and high-mobility group box chromosomal protein 1 (HMGB1), both in vitro and in vivo and partially improved experimental sepsis survival.

CONCLUSIONS

These findings support the existence of a synergistic effect of Notch signaling and the LPS pathway both in vitro and in vivo. Therefore, in the future Notch inhibitors may be utilized as adjunctive agents for the treatment of sepsis syndrome.

Notch signaling prevents mucous metaplasia in mouse conducting airways during postnatal development

Goblet cell metaplasia and mucus overproduction contribute to the pathogenesis of chronic lung diseases, including asthma and chronic obstructive pulmonary disease (COPD). Notch signaling regulates cell fate decisions and is crucial in controlling goblet cell differentiation in the gut epithelium. Little is known, however, about how endogenous Notch signaling influences the goblet cell differentiation program that takes place in the postnatal lung. Using a combination of genetic and in vitro approaches here we provide evidence of a novel role for Notch in restricting goblet cell differentiation in the airway epithelium during the postnatal period. Conditional inactivation of the essential Notch pathway component Pofut1 (protein O-fucosyltransferase1) in Tgfb3-Cre-expressing mice resulted in an aberrant postnatal airway phenotype characterized by marked goblet cell metaplasia, decreased Clara cell number and increase in ciliated cells. The presence of the same phenotype in mice in which the Notch transcriptional effector Rbpjk was deleted indicated the involvement of the canonical Notch pathway. Lineage study in vivo suggested that goblet cells originated from a subpopulation of Clara cells largely present in proximal airways in which Notch was disrupted. The phenotype was confirmed by a panel of goblet cell markers, showed no changes in cell proliferation or altered expression of proinflammatory cytokines and was associated with significant downregulation of the bHLH transcriptional repressor Hes5. Luciferase reporter analysis suggested that Notch directly repressed MUC5AC transcription in lung epithelial cells. The data suggested that during postnatal life Notch is required to prevent Clara cells from differentiating into goblet cells.

Sepsis and acute kidney injury

Sepsis is a severe and dysregulated inflammatory response to infection characterized by end-organ dysfunction distant from the primary site of infection. Development of acute kidney injury (AKI) during sepsis increases patient morbidity, predicts higher mortality, has a significant effect on multiple organ functions, is associated with an increased length of stay in the intensive care unit, and hence consumes considerable healthcare resources. When compared with AKI of nonseptic origin, septic AKI is characterized by a distinct pathophysiology and therefore requires a different approach. Despite impressive advances in several fields of medicine, the pathophysiology, diagnostic procedures, and appropriate therapeutic interventions in sepsis are still highly debatable. Numerous immunomodulatory agents showing promise in preclinical studies fail to reduce the overwhelmingly high mortality rate of sepsis and provoke AKI when compared with other critically ill patients. Major impediments to progress in understanding, early diagnosis, and application of appropriate therapeutic modalities in sepsis-induced AKI include limited histopathologic information, few animal models that closely mimic human sepsis, and a relative shortage of specific diagnostic tools. Here we discuss the most recent advances in understanding the fundamental mechanisms of sepsis-induced AKI, characteristics of relevant animal models available, and potential therapies.

Role of vascular endothelial growth factor-A in development of abdominal aortic aneurysm

AIMS

Increased angiogenesis, chronic inflammation, and extracellular matrix degradation are the major pathological features of abdominal aortic aneurysm (AAA). We sought to elucidate the role of vascular endothelial growth factor (VEGF)-A, a potent angiogenic and proinflammatory factor, in the development of AAA.

METHODS AND RESULTS

Human AAA samples showed increased VEGF-A expression, neovascularization, and macrophage infiltration compared with normal aortic walls. AAA was induced in mice by periaortic application of CaCl(2). AAA mice were treated with soluble VEGF-A receptor (sFlt)-1 or phosphate-buffered saline and sacrificed 6 weeks after the operation. Treatment with sFlt-1 resulted in reduced aneurysm size, restored wavy structure of the elastic lamellae, reduced Mac-2(+) monocytes/macrophages, CD3(+) T-lymphocytes, and CD31(+) vessels, and attenuated matrix metalloproteinase (MMP)-2 and 9 activity in periaortic tissue of AAA. Increased aortic mRNA expression of monocyte chemotactic protein-1, tumour necrosis factor-α, and intercellular adhesion molecule-1 in AAA was attenuated by sFlt-1 treatment.

CONCLUSION

VEGF-A was overexpressed in the aortic wall of human and experimental AAA. Treatment with sFlt-1 inhibited AAA development in mice, in association with reduced neoangiogenesis, infiltration of inflammatory cells, MMP activity, and extracellular matrix degradation. These findings suggest a crucial role of VEGF-A in the development of AAA.

Sepsis and the broken endothelium

The study by Yang and colleagues examined 81 patients with septic shock due to pneumonia, along with 20 patients with pneumonia without organ dysfunction. Their major findings were that circulating levels of soluble vascular endothelial cell growth factor receptor-1 (sVEGFR-1) and urokinase-type plasminogen activator (uPA) were associated with organ dysfunction and mortality, whereas vascular endothelial cell growth factor (VEGF) levels had no such predictive power. Yang and colleagues are to be complimented for a well-conducted study of a reasonably (and helpfully!) homogeneous population of patients with sepsis that carefully and comprehensively analyzed the relationship between sVEGFR-1, uPA, VEGF and clinical outcome. The study serves not only to provide evidence in support of new diagnostic biomarker targets in sepsis, but also to augment the growing evidence of an important role of the endothelium in sepsis in general, and the VEGF signaling axis in particular.

Time-course of sFlt-1 and VEGF-A release in neutropenic patients with sepsis and septic shock: a prospective study

Background

Septic shock is the most feared complication of chemotherapy-induced febrile neutropenia. So far, there are no robust biomarkers that can stratify patients to the risk of sepsis complications. The VEGF-A axis is involved in the control of microvascular permeability and has been involved in the pathogenesis of conditions associated with endothelial barrier disruption such as sepsis. sFlt-1 is a soluble variant of the VEGF-A receptor VEGFR-1 that acts as a decoy receptor down-regulating the effects of VEGF-A. In animal models of sepsis, sFlt-1 was capable to block the barrier-breaking negative effects of VEGF-A and to significantly decrease mortality. In non-neutropenic patients, sFlt-1 has been shown to be a promising biomarker for sepsis severity.

Methods

We prospectively evaluated concentrations of sFlt-1 and VEGF-A at different time-points during febrile neutropenia, and evaluated the association of these levels with sepsis severity and septic shock development.

Results

Neutropenic patients that evolved with septic shock (n = 10) presented higher levels of sFlt-1 and VEGF-A measured 48 hours after fever onset than patients with non-complicated sepsis (n = 31) and levels of these biomarkers correlated with sepsis severity scores. Estimation of the diagnostic accuracy of sFlt-1 levels for the discrimination of patients that evolved to septic shock yielded promising results in our study population.

Discussion

Our data suggest that sFlt-1 and VEGF-A could be useful biomarkers for sepsis severity in patients with febrile neutropenia. In addition, the kinetics of sFlt-1 release in patients that evolve to septic shock suggest that the sFlt-1 could be a salvage compensatory mechanism in patients with septic shock, but that the magnitude of the sFlt-1 release observed in human sepsis is not sufficient to reproduce the beneficial anti-VEGF-A effects observed in animal models of sepsis.

Unexplained fetal death is associated with increased concentrations of anti-angiogenic factors in amniotic fluid

OBJECTIVE

Angiogenesis is critical for successful pregnancy. An anti-angiogenic state has been implicated in preeclampsia, fetal growth restriction and fetal death. Increased maternal plasma concentrations of the anti-angiogenic factor, soluble vascular endothelial growth factor receptor (sVEGFR)-1, have been reported in women with preeclampsia and in those with fetal death. Recent observations indicate that an excess of sVEGFR-1 and soluble endoglin (sEng) is also present in the amniotic fluid of patients with preeclampsia. The aim of this study was to determine whether fetal death is associated with changes in amniotic fluid concentrations of sVEGFR-1 and sEng, two powerful anti-angiogenic factors. Study design. This cross-sectional study included patients with fetal death (n = 35) and controls (n = 129). Fetal death was subdivided according to clinical circumstances into: (1) unexplained (n = 25); (2) preeclampsia and/or placental abruption (n = 5); and (3) chromosomal/congenital anomalies (n = 5). The control group consisted of patients with preterm labor (PTL) who delivered at term (n = 92) and women at term not in labor (n = 37). AF concentrations of sVEGFR-1 and sEng were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied. Results. (1) Patients with a fetal death had higher median amniotic fluid concentrations of sVEGFR-1 and sEng than women in the control group (p < 0.001 for each); (2) these results remained significant among different subgroups of stillbirth (p < 0.05 for each); and (3) amniotic fluid concentrations of sVEGFR-1 and those of sEng above the third quartile were associated with a significant risk of unexplained preterm fetal death (adjusted OR = 10.8; 95%CI 1.3-89.2 and adjusted OR 87; 95% CI 2.3-3323, respectively). Conclusion. Patients with an unexplained fetal death at diagnosis are characterized by an increase in the amniotic fluid concentrations of sVEGFR-1 and sEng. These observations indicate that an excess of anti-angiogenic factors in the amniotic cavity is associated with unexplained fetal death especially in preterm gestations.

Comparative effects of probiotics, prebiotics, and synbiotics on growth factors in the large bowel in a rat model of formula-induced bowel inflammation

OBJECTIVES

Supplementation with probiotics has been shown to prevent gastrointestinal damage possibly through preservation of growth factors. We tested the hypothesis that probiotics, prebiotics, or synbiotics supplementation preserves intestinal insulin-like growth factors (IGFs) and epidermal growth factors (EGFs) in formula-fed neonatal rats.

MATERIALS AND METHODS

At birth (postnatal day 0 [P0]), neonatal rat pups (n = 18 pups/group) were either maternally fed or hand-gavaged with formula supplemented with probiotics (Pro-Fed), prebiotics, or synbiotics from P0 to P3. A formula-fed control group received formula without supplementation. At P4, large bowel samples were assessed histologically and assayed for vascular endothelial growth factor (VEGF), soluble VEGF receptor-1, IGF-I, IGF-II, and EGF.

RESULTS

All formula-fed groups were severely growth suppressed with comparable mortalities. Moderate preservation of bowel integrity was noted in the Pro-Fed group. In contrast, severe inflammation was seen in all of the other formula groups. This was associated with significant increases in VEGF levels in all of the formula groups (P < 0.05) except the Pre-Fed group. Similar elevations in soluble VEGF receptor-1 (P < 0.05), IGF-I (P < 0.05), and EGF (P < 0.05) were noted, but statistical significance was achieved only in the Pro-Fed group.

CONCLUSIONS

Induction of IGF-I and EGF with moderate bowel integrity may represent a protective effect of probiotics against formula-induced inflammation. These data, taken collectively, suggest that probiotics may provide more beneficial effects on the developing large bowel than prebiotics and synbiotics.

Evidence in support of a role for anti-angiogenic factors in preterm prelabor rupture of membranes

OBJECTIVE

Vaginal bleeding, placental abruption, and defective placentation are frequently observed in patients with preterm prelabor rupture of membranes (PROM). Recently, a role of vascular endothelial growth factor (VEGF) and its receptor, VEGF receptor (VEGFR)- 1 has been implicated in the mechanisms of membrane rupture. The purpose of this study was to determine whether the soluble form of VEGFR-1 and -2 concentrations in amniotic fluid (AF) change with preterm PROM, intra-amniotic infection/inflammation (IAI), or parturition.

STUDY DESIGN

This cross-sectional study included 544 patients in the following groups: (1) midtrimester (MT) (n = 48); (2) preterm labor (PTL) leading to term delivery (n = 143); (3) PTL resulting in preterm delivery with (n = 72) and without IAI (n = 100); (4) preterm PROM with (n = 46) and without IAI (n = 42); (5) term in labor (n = 48); and (6) term not in labor (n = 45). The concentrations of sVEGFR-1 and sVEGFR-2 were determined by ELISA. Non-parametric statistics and logistic regression analysis were applied.

RESULTS

(1) Preterm PROM (with and without IAI) had a lower median AF concentration of sVEGFR-1 than patients with PTL who delivered at term (p < 0.001 for each comparison); (2) A decrease in AFsVEGFR-1 concentrations per each quartile was associated with PROM after adjusting for confounders (OR 1.8; 95%CI 1.4-2.3); (3) IAI, regardless of the membrane status, was not associated with a change in the median AF concentrations of sVEGFR-1 and sVEGFR-2 (p > 0.05 for each comparison); and (4) Spontaneous term and PTL did not change the median sVEGFR-1 and sVEGFR-2 concentrations (p > 0.05 for each comparison).

CONCLUSION

(1) This is the first evidence that preterm PROM is associated with a lower AF concentration of sVEGFR-1 than patients with PTL intact membranes. These findings cannot be attributed to gestational age, labor, or IAI; and (2) AF concentrations of sVEGFR-2 did not change with preterm PROM, IAI, or labor at term and preterm.

Acute pyelonephritis during pregnancy changes the balance of angiogenic and anti-angiogenic factors in maternal plasma

OBJECTIVE

Angiogenic factors have been implicated in the pathophysiology of sepsis. In experimental models of sepsis (endotoxemia and/or cecal ligation puncture), there is increased expression of vascular endothelial growth factors (VEGF) and the administration of exogenous soluble VEGF receptor (sVEGFR)-1, an antagonist to VEGF, reduces morbidity and mortality. Moreover, a dramatic elevation in sVEGFR-1 has been demonstrated in human sepsis. Although a balance between angiogenic and anti-angiogenic factors is essential for feto-placental development, the changes of angiogenic factors during pregnancy in the context of infection have never been explored. Angiogenic factors also play crucial roles in the pathophysiology of preeclampsia (PE). This study was conducted to determine if maternal plasma concentrations of placental growth factor (PlGF), sVEGFR-2, and soluble endoglin (sEng) change in pregnancies complicated by acute pyelonephritis (AP) compared with normal pregnancy and PE.

STUDY DESIGN

A case-control study was conducted in patients with AP, normal pregnant (NP) women, and patients with PE (n=36 for each group) matched for gestational age. AP was diagnosed in the presence of fever (temperature >or=38 degrees C), clinical signs of infection, and a positive urine culture for microorganisms. Plasma concentrations of PlGF, sVEGFR-2, and sEng were determined by ELISA. The results of plasma sVEGFR-1 concentrations have previously been reported, but were included in this study to provide a complete picture of the angiogenic/anti-angiogenic profiles. Serum concentrations of interleukin (IL)-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12p70, IL-13, interferon (IFN)-gamma, granulocyte macrophage colony stimulating factor, and tumor necrosis factor (TNF) were also determined using high sensitivity multiplexed immunoassays in patients with AP and NP.

RESULTS

AP was associated with a lower median plasma concentration of PlGF and sVEGFR-2 than NP (both p<0.001). There were no significant differences in the median plasma concentrations of sEng and sVEGFR-1 between AP and NP (p=0.7 and 0.5, respectively). In contrast, there was a 5-fold decrease of the median plasma concentration of PlGF, and an 8-10-fold increase of the median plasma concentrations of sVEGFR-1 and sEng in PE compared with those in AP (all p<0.001). No significant difference in the median plasma concentration of sVEGFR-2 was observed between patients with PE and AP (p=0.5). Pregnant women with AP had median plasma concentrations of IL-6, IL-7, IL-8, IL-10, IFN-gamma, and TNF-alpha significantly higher than those in NP women (all p<0.001, except IL-7 p=0.004).

CONCLUSION

AP is associated with changes in the profile of angiogenic and anti-angiogenic factors. Although some of these changes resemble those in PE (decreased PlGF and sVEGFR-2), the magnitude of the changes of PlGF is much higher in PE. We conclude that despite high plasma inflammatory cytokine concentrations, acute systemic inflammation in pregnancy has a different angiogenic/anti-angiogenic profile than that of PE.

Sepsis biomarkers: a review

INTRODUCTION

Biomarkers can be useful for identifying or ruling out sepsis, identifying patients who may benefit from specific therapies or assessing the response to therapy.

METHODS

We used an electronic search of the PubMed database using the key words "sepsis" and "biomarker" to identify clinical and experimental studies which evaluated a biomarker in sepsis.

RESULTS

The search retrieved 3370 references covering 178 different biomarkers.

CONCLUSIONS

Many biomarkers have been evaluated for use in sepsis. Most of the biomarkers had been tested clinically, primarily as prognostic markers in sepsis; relatively few have been used for diagnosis. None has sufficient specificity or sensitivity to be routinely employed in clinical practice. PCT and CRP have been most widely used, but even these have limited ability to distinguish sepsis from other inflammatory conditions or to predict outcome.

A systems biology perspective on sVEGFR1: its biological function, pathogenic role and therapeutic use

Angiogenesis is the growth of new capillaries from pre-existent microvasculature. A wide range of pathological conditions, from atherosclerosis to cancer, can be attributed to either excessive or deficient angiogenesis. Central to the physiological regulation of angiogenesis is the vascular endothelial growth factor (VEGF) system – its ligands and receptors (VEGFRs) are thus prime molecular targets of pro-angiogenic and anti-angiogenic therapies. Of growing interest as a prognostic marker and therapeutic target in angiogenesis-dependent diseases is soluble VEGF receptor-1 (sVEGFR1, also known as sFlt-1) – a truncated version of the cell membrane-spanning VEGFR1. For instance, it is known that sVEGFR1 is involved in the endothelial dysfunction characterizing the pregnancy disorder of pre-eclampsia, and sVEGFR1’s therapeutic potential as an anti-angiogenic agent is being evaluated in pre-clinical models of cancer. This mini review begins with an examination of the protein domain structure and biomolecular interactions of sVEGFR1 in relation to the full-length VEGFR1. A synopsis of known and inferred physiological and pathological roles of sVEGFR1 is then given, with emphasis on the utility of computational systems biology models in deciphering the molecular mechanisms by which sVEGFR1’s purported biological functions occur. Finally, we present the need for a systems biology perspective in interpreting circulating VEGF and sVEGFR1 concentrations as surrogate markers of angiogenic status in angiogenesis-dependent diseases.

Preoperative serum placenta growth factor level is a prognostic biomarker in colorectal cancer

PURPOSE

Increased angiogenesis at the site of the primary tumor in colorectal cancer has been associated with poor prognosis and relapse of disease. We previously demonstrated that the tissue level of placenta growth factor expression was upregulated in colorectal cancer and correlated with disease progression and patient survival. The aims of this study are to examine the prognostic value of serum placenta growth factor, vascular endothelial growth factor, and sFlt-1 and to compare them with the carcinoembryonic antigen levels in patients with colorectal cancer.

METHODS

Preoperative serum from 86 patients and serum from 30 healthy controls was included. The levels of sFlt-1, placenta growth factor, vascular endothelial growth factor in the serum were assayed and correlated with the clinical stage results.

RESULTS

Serum placenta growth factor, but not vascular endothelial growth factor, increased; sFlt-1 decreased in patients with preoperative colorectal cancer, compared with healthy controls. Higher preoperation serum placenta growth factor levels were associated with higher risk of recurrence. Preoperation serum placenta growth factor, but not carcinoembryonic antigen, was a prognostic indicator in patients with Stage III colorectal cancer. When we use the median level (20.6 pg/ml) of preoperative serum placenta growth factor as a cutoff point, the sensitivity, specificity, and positive predictive value for tumor recurrence and survival was 80, 54, 80% and 70, 56, 70%, respectively.

CONCLUSIONS

Preoperative serum placenta growth factor levels were higher in patients with colorectal cancer, were negatively correlated with the serum sFlt-1, and could be used as a prognostic indicator for recurrence and survival for colorectal cancer.

A potential role for reactive oxygen species and the HIF-1alpha-VEGF pathway in hypoxia-induced pulmonary vascular leak

Acute hypoxia causes pulmonary vascular leak and is involved in the pathogenesis of pulmonary edema associated with inflammation, acute altitude exposure, and other critical illnesses. Reactive oxygen species, HIF-1, and VEGF have all been implicated in various hypoxic pathologies, yet the ROS-HIF-1-VEGF pathway in pulmonary vascular leak has not been defined. We hypothesized that the ROS-HIF-1-VEGF pathway has an important role in producing hypoxia-induced pulmonary vascular leak. Human pulmonary artery endothelial cell (HPAEC) monolayers were exposed to either normoxia (21% O(2)) or acute hypoxia (3% O(2)) for 24 h and monolayer permeability and H(2)O(2), nuclear HIF-1alpha, and cytosolic VEGF levels were determined. HPAEC were treated with antioxidant cocktail (AO; ascorbate, glutathione, and alpha-tocopherol), HIF-1 siRNA, or the VEGF soluble binding protein fms-like tyrosine kinase-1 (sFlt-1) to delineate the role of the ROS-HIF-1-VEGF pathway in hypoxia-induced HPAEC leak. Additionally, mice exposed to hypobaric hypoxia (18,000 ft, 10% O(2)) were treated with the same antioxidant to determine if in vitro responses corresponded to in vivo hypoxia stress. Hypoxia increased albumin permeativity, H(2)O(2) production, and nuclear HIF-1alpha and cytosolic VEGF concentration. Treatment with an AO lowered the hypoxia-induced HPAEC monolayer permeability as well as the elevation of HIF-1alpha and VEGF. Treatment of hypoxia-induced HPAEC with either an siRNA designed against HIF-1alpha or the VEGF antagonist sFlt-1 decreased monolayer permeability. Mice treated with AO and exposed to hypobaric hypoxia (18,000 ft, 10% O(2)) had less pulmonary vascular leak than those that were untreated. Our data suggest that hypoxia-induced permeability is due, in part, to the ROS-HIF-1alpha-VEGF pathway.

A compartment model of VEGF distribution in humans in the presence of soluble VEGF receptor-1 acting as a ligand trap

Vascular endothelial growth factor (VEGF), through its activation of cell surface receptor tyrosine kinases including VEGFR1 and VEGFR2, is a vital regulator of stimulatory and inhibitory processes that keep angiogenesis--new capillary growth from existing microvasculature--at a dynamic balance in normal physiology. Soluble VEGF receptor-1 (sVEGFR1)--a naturally-occurring truncated version of VEGFR1 lacking the transmembrane and intracellular signaling domains--has been postulated to exert inhibitory effects on angiogenic signaling via two mechanisms: direct sequestration of angiogenic ligands such as VEGF; or dominant-negative heterodimerization with surface VEGFRs. In pre-clinical studies, sVEGFR1 gene and protein therapy have demonstrated efficacy in inhibiting tumor angiogenesis; while in clinical studies, sVEGFR1 has shown utility as a diagnostic or prognostic marker in a widening array of angiogenesis-dependent diseases. Here we developed a novel computational multi-tissue model for recapitulating the dynamic systemic distributions of VEGF and sVEGFR1. Model features included: physiologically-based multi-scale compartmentalization of the human body; inter-compartmental macromolecular biotransport processes (vascular permeability, lymphatic drainage); and molecularly-detailed binding interactions between the ligand isoforms VEGF(121) and VEGF(165), signaling receptors VEGFR1 and VEGFR2, non-signaling co-receptor neuropilin-1 (NRP1), as well as sVEGFR1. The model was parameterized to represent a healthy human subject, whereupon we investigated the effects of sVEGFR1 on the distribution and activation of VEGF ligands and receptors. We assessed the healthy baseline stability of circulating VEGF and sVEGFR1 levels in plasma, as well as their reliability in indicating tissue-level angiogenic signaling potential. Unexpectedly, simulated results showed that sVEGFR1 - acting as a diffusible VEGF sink alone, i.e., without sVEGFR1-VEGFR heterodimerization--did not significantly lower interstitial VEGF, nor inhibit signaling potential in tissues. Additionally, the sensitivity of plasma VEGF and sVEGFR1 to physiological fluctuations in transport rates may partially account for the heterogeneity in clinical measurements of these circulating angiogenic markers, potentially hindering their diagnostic reliability for diseases.

Relationship between circulating vascular endothelial growth factor and its soluble receptors in adults with dengue virus infection: a case-control study

BACKGROUND

We performed a case-control study to assess the relationship between vascular endothelial growth factor (VEGF) and its soluble receptors (sVEGFR-1 and 2) in adult patients with dengue fever (DF) and dengue hemorrhagic fever (DHF).

METHODS

We recruited 60 adult patients (34 DF and 26 DHF) with serologically-confirmed dengue infections, 10 patients with non-hemorrhagic infections, and 31 community-based healthy volunteers. The levels of VEGF, sVEGFR-1, and sVEGFR-2 were measured and the differences in these markers were compared using one-way analysis of variance (ANOVA), which was adjusted for multiple comparisons.

RESULTS

We observed lower VEGF levels in DF and DHF compared to study controls (p<0.01). sVEGFR-1 was higher in DHF than DF, whilst sVEGFR-2 was lower in DF and DHF compared to study controls (all p<0.01). In DHF, lower VEGF levels were observed in older patients. The use of a single marker, sVEGFR-1>350 pg/ml, was predictive of DHF.

CONCLUSION

The changes in VEGF and its soluble receptors highlight the importance of vascular permeability cytokines in the pathogenesis of DHF.

Elevated levels of placental growth factor represent an adaptive host response in sepsis

Recently, we demonstrated that circulating levels of vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) are increased in sepsis (Yano, K., P.C. Liaw, J.M. Mullington, S.C. Shih, H. Okada, N. Bodyak, P.M. Kang, L. Toltl, B. Belikoff, J. Buras, et al. 2006. J. Exp. Med. 203:1447–1458). Moreover, enhanced VEGF/Flk-1 signaling was shown to contribute to sepsis morbidity and mortality. We tested the hypothesis that PlGF also contributes to sepsis outcome. In mouse models of endotoxemia and cecal ligation puncture, the genetic absence of PlGF or the systemic administration of neutralizing anti-PlGF antibodies resulted in higher mortality compared with wild-type or immunoglobulin G–injected controls, respectively. The increased mortality associated with genetic deficiency of PlGF was reversed by adenovirus (Ad)-mediated overexpression of PlGF. In the endotoxemia model, PlGF deficiency was associated with elevated circulating levels of VEGF, induction of VEGF expression in the liver, impaired cardiac function, and organ-specific accentuation of barrier dysfunction and inflammation. Mortality of endotoxemic PlGF-deficient mice was increased by Ad-mediated overexpression of VEGF and was blocked by expression of soluble Flt-1. Collectively, these data suggest that up-regulation of PlGF in sepsis is an adaptive host response that exerts its benefit, at least in part, by attenuating VEGF signaling.

Pre-existing renal disease promotes sepsis-induced acute kidney injury and worsens outcome

While it is known that risk of death from sepsis is higher in patients with pre-existing chronic kidney disease its mechanism is unknown. To study this we established a two-stage mouse model where renal disease was first induced by folic acid injection followed by sub-lethal cecal ligation and puncture to induce sepsis. Septic mice with pre-existing renal disease had significantly higher mortality, serum creatinine, vascular permeability, plasma vascular endothelial growth factor (VEGF) levels, bacteremia, serum IL-10, splenocyte apoptosis and more severe septic shock when compared to septic mice without pre-existing disease. To evaluate the contribution of vascular and immunological dysfunction, we treated the folate-septic mice with soluble Flt-1 to bind VEGF and chloroquine to reduce splenocyte apoptosis. These treatments together resulted in a significant improvement in kidney injury, hemodynamics and survival. Our study shows that the sequential mouse model mimics human sepsis frequently complicated by pre-existing renal disease and might be useful in evaluating preventive and therapeutic strategies.

Novel PKC signaling is required for LPS-induced soluble Flt-1 expression in macrophages

In vitro activation of macrophages by LPS induces rapid release of vascular endothelial growth factor (VEGF) and soluble fms-like tyrosine kinase-1 receptor (sFlt-1), which are thought to be the effectors to cause sepsis. However, the signal pathway that controls the VEGF and sFlt-1 expressions in LPS-activated macrophages remains unclear. In this study, we demonstrated that phosphorylation of protein kinase C (PKC)delta played a key role in the VEGF and sFlt-1 signaling pathway of LPS-activated macrophages. PKC is a family of serine-threonine kinases, which are classified into three major groups based on homology and cofactor requirements: conventional PKCs, novel PKCs, and atypical PKCs. In the murine RAW264.7 cells, as well as in primary human monocytes/macrophages, pretreatment with a general PKC inhibitor GF109203X or with a novel PKCdelta inhibitor rottlerin or overexpression of a kinase-inactive form of PKCdelta (K376R) eliminated LPS-induced sFlt-1 expression and augmented LPS-induced VEGF expression at the protein and the transcription levels. In contrast, Gö6976, an inhibitor for the conventional PKCs, or myristoylated PKCzeta pseudosubstrate peptide, an inhibitor for the atypical PKCs, failed to exert the same effects. These data suggest that PKCdelta signaling is involved in LPS-induced sFlt-1 expression and serves as a negative mediator in LPS-induced VEGF expression in macrophages. A novel strategy controlling the LPS-induced PKC pathways, especially the PKCdelta isoform, may be developed based on this study.