A vascular perspective on neuronal migration.

During CNS development and adult neurogenesis, immature neurons travel from the germinal zones towards their final destination using cellular substrates for their migration. Classically, radial glia and neuronal axons have been shown to act as physical scaffolds to support neuroblast locomotion in processes known as gliophilic and neurophilic migration, respectively (Hatten, 1999; Marin and Rubenstein, 2003; Rakic, 2003). In adulthood, long distance neuronal migration occurs in a glial-independent manner since radial glia cells differentiate into astrocytes after birth. A series of studies highlight a novel mode of neuronal migration that uses blood vessels as scaffolds, the so-called vasophilic migration. This migration mode allows neuroblast navigation in physiological and also pathological conditions, such as neuronal precursor migration after ischemic stroke or cerebral invasion of glioma tumor cells. Here we review the current knowledge about how vessels pave the path for migrating neurons and how trophic factors derived by glio-vascular structures guide neuronal migration both during physiological as well as pathological processes.

EphrinB2 controls vessel pruning through STAT1-JNK3 signalling.

Angiogenesis produces primitive vascular networks that need pruning to yield hierarchically organized and functional vessels. Despite the critical importance of vessel pruning to vessel patterning and function, the mechanisms regulating this process are not clear. Here we show that EphrinB2, a well-known player in angiogenesis, is an essential regulator of endothelial cell death and vessel pruning. This regulation depends upon phosphotyrosine-EphrinB2 signalling repressing c-jun N-terminal kinase 3 activity via STAT1. JNK3 activation causes endothelial cell death. In the absence of JNK3, hyaloid vessel physiological pruning is impaired, associated with abnormal persistence of hyaloid vessels, defective retinal vasculature and microphthalmia. This syndrome closely resembles human persistent hyperplastic primary vitreus (PHPV), attributed to failed involution of hyaloid vessels. Our results provide evidence that EphrinB2/STAT1/JNK3 signalling is essential for vessel pruning, and that defects in this pathway may contribute to PHPV.

Increased IL-17A expression in temporal artery lesions is a predictor of sustained response to glucocorticoid treatment in patients with giant-cell arteritis.

BACKGROUND: Interleukin 17A (IL-17A) exerts pivotal proinflammatory functions in chronic inflammatory and autoimmune diseases. OBJECTIVE: To investigate IL-17A expression in temporal artery lesions from patients with giant-cell arteritis (GCA), and its relationship with disease outcome. METHODS: Fifty-seven patients with biopsy-proven GCA were prospectively evaluated, treated and followed for 4.5 years (52-464 weeks). Relapses, time (weeks) required to achieve a maintenance prednisone dose <10 mg/day, and time (weeks) to complete prednisone withdrawal were prospectively recorded. IL-17A mRNA was measured by real-time quantitative RT-PCR in temporal arteries from all patients and 19 controls. IL-17 protein expression was assessed by immunohistochemistry/immunofluorescence. RESULTS: IL-17A expression was significantly increased in temporal artery samples from GCA patients compared with controls (6.22±8.61 vs 2.50±3.9 relative units, p=0.016). Surprisingly, patients with strong IL-17A expression tended to experience less relapses, and required significantly shorter treatment periods (median 25 vs 44 weeks to achieve <10 mg prednisone/day, p=0.0079). There was no correlation between IL-17A and RORc or RORα expression suggesting that these transcription factors may not exclusively reflect Th17 differentiation, and that cells other than Th17 cells might contribute to IL-17 expression in active patients. Accordingly, FoxP3(+)IL-17A(+) cells were identified in lesions by confocal microscopy and were dramatically reduced in specimens from treated patients. CONCLUSIONS: IL-17A expression is increased in GCA lesions, and is a predictor of response to glucocorticoid treatment. The contribution of FoxP3+ cells to IL-17A production in untreated patients suggests that induced-Tregs may facilitate disease remission when proinflammatory cytokine production is downregulated by glucocorticosteroids.

Semaphorin 6A regulates angiogenesis by modulating VEGF signaling.

Formation of new vessels during development and in the mature mammal generally proceeds through angiogenesis. Although a variety of molecules and signaling pathways are known to underlie endothelial cell sprouting and remodeling during angiogenesis, many aspects of this complex process remain unexplained. Here we show that the transmembrane semaphorin6A (Sema6A) is expressed in endothelial cells, and regulates endothelial cell survival and growth by modulating the expression and signaling of VEGFR2, which is known to maintain endothelial cell viability by autocrine VEGFR signaling. The silencing of Sema6A in primary endothelial cells promotes cell death that is not rescued by exogenous VEGF-A or FGF2, attributable to the loss of prosurvival signaling from endogenous VEGF. Analyses of mouse tissues demonstrate that Sema6A is expressed in angiogenic and remodeling vessels. Mice with null mutations of Sema6A exhibit significant defects in hyaloid vessels complexity associated with increased endothelial cell death, and in retinal vessels development that is abnormally reduced. Adult Sema6A-null mice exhibit reduced tumor, matrigel, and choroidal angiogenesis compared with controls. Sema6A plays important roles in development of the nervous system. Here we show that it also regulates vascular development and adult angiogenesis.

Adult human circulating CD34⁻Lin⁻CD45⁻CD133⁻ cells can differentiate into hematopoietic and endothelial cells.

A precise identification of adult human hemangioblast is still lacking. To identify circulating precursors having the developmental potential of the hemangioblast, we established a new ex vivo long-term culture model supporting the differentiation of both hematopoietic and endothelial cell lineages. We identified from peripheral blood a population lacking the expression of CD34, lineage markers, CD45 and CD133 (CD34⁻Lin⁻CD45⁻CD133⁻ cells), endowed with the ability to differentiate after a 6-week culture into both hematopoietic and endothelial lineages. The bilineage potential of CD34⁻Lin⁻CD45⁻CD133⁻ cells was determined at the single-cell level in vitro and was confirmed by transplantation into NOD/SCID mice. In vivo, CD34⁻Lin⁻CD45⁻CD133⁻ cells showed the ability to reconstitute hematopoietic tissue and to generate functional endothelial cells that contribute to new vessel formation during tumor angiogenesis. Molecular characterization of CD34⁻Lin⁻D45⁻CD133⁻ cells unveiled a stem cell profile compatible with both hematopoietic and endothelial potentials, characterized by the expression of c-Kit and CXCR4 as well as EphB4, EphB2, and ephrinB2. Further molecular and functional characterization of CD34⁻Lin⁻CD45⁻CD133⁻ cells will help dissect their physiologic role in blood and blood vessel maintenance and repair in adult life.

Oligo-guanosine nucleotide induces neuropilin-1 internalization in endothelial cells and inhibits angiogenesis.

Ligand interaction with cognate cell-surface receptor often promotes receptor internalization, protecting cells from prolonged or excessive signaling from extracellular ligands. Compounds that induce internalization of surface receptors prevent ligand binding to cognate cell-surface receptors serving as inhibitors. Here, we show that synthetic polyriboguanosine (poly G) and oligo-deoxyriboguanosine (oligo G) reduce endothelial levels of surface neuropilin-1 (NRP1), a receptor shared by semaphorin 3A and vascular endothelial growth factor (VEGF), which plays critical roles in angiogenesis. Oligo G also reduces levels of cell-surface scavenger receptor expressed by endothelial cells I (SREC-I), but not levels of NRP2, gp130, CD31, VEGFR-1, or VEGFR-2. Poly or oligo A, T, and C do not promote NRP1 or SREC-I internalization. We find that oligo G binds to NRP1 with high affinity (Kd:1.3 ± 0.16 nM), bridges the extracellular domain of NRP1 to that of SREC-I, and induces coordinate internalization of NRP1 and SREC-I. In vitro, oligo G blocks the binding and function of VEGF(165) in endothelial cells. In vivo, intravitreal administration of oligo G reduces choroidal neovascularization in mice. These results demonstrate that synthetic oligo G is an inhibitor of pathologic angiogenesis that reduces cell-surface levels and function of NRP1 acting as an internalization inducer.

Clinical relevance of persistently elevated circulating cytokines (tumor necrosis factor alpha and interleukin-6) in the long-term followup of patients with giant cell arteritis.

OBJECTIVE: To assess the clinical relevance of increased circulating cytokines in patients with giant cell arteritis (GCA) after long-term followup. METHODS: We performed a cross-sectional evaluation of 54 patients with biopsy-proven GCA prospectively followed for a median of 5.4 years (range 4-10.5 years). GCA-related complications, vascular events, relapses, current prednisone dose, time required to achieve a maintenance prednisone dosage <10 mg/day, cumulated prednisone at that point, and adverse effects during followup were recorded. Serum interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFalpha) were determined by immunoassay. RESULTS: All patients were in clinical remission. Both cytokines were significantly higher in patients than in controls (mean +/- SD 21 +/- 35 versus 5 +/- 11 pg/ml; P < 0.001 for IL-6 and mean +/- SD 32 +/- 14 versus 16 +/- 9 pg/ml; P < 0.001 for TNFalpha). No differences were found in patients with or without GCA-related complications or vascular events during followup. Circulating cytokines were significantly higher in patients who had experienced relapses (mean +/- SD 25 +/- 39 versus 10 +/- 11 pg/ml; P = 0.04 for IL-6 and mean +/- SD 34 +/- 15 versus 25 +/- 11 pg/ml; P = 0.042 for TNFalpha). IL-6 was significantly higher in patients still requiring prednisone (mean +/- SD 29 +/- 45 versus 13 +/- 17 pg/ml; P = 0.008), and TNFalpha correlated with cumulated prednisone dose (r = 0.292, P = 0.04). No significant relationship was found between elevated cytokines and prednisone adverse effects or patients' quality of life. CONCLUSION: Circulating TNFalpha and IL-6 may persist elevated in GCA patients after long-term followup and remain higher in patients who have experienced more relapsing disease. However, in this patient cohort, elevated circulating cytokines were not associated with increased frequency of GCA complications, vascular events, or treatment-related side effects.

The transcription factor Gfi1 regulates G-CSF signaling and neutrophil development through the Ras activator RasGRP1.

The transcription factor growth factor independence 1 (Gfi1) and the growth factor granulocyte colony-stimulating factor (G-CSF) are individually essential for neutrophil differentiation from myeloid progenitors. Here, we provide evidence that the functions of Gfi1 and G-CSF are linked in the regulation of granulopoiesis. We report that Gfi1 promotes the expression of Ras guanine nucleotide releasing protein 1 (RasGRP1), an exchange factor that activates Ras, and that RasGRP1 is required for G-CSF signaling through the Ras/mitogen-activated protein/extracellular signal-regulated kinase (MEK/Erk) pathway. Gfi1-null mice have reduced levels of RasGRP1 mRNA and protein in thymus, spleen, and bone marrow, and Gfi1 transduction in myeloid cells promotes RasGRP1 expression. When stimulated with G-CSF, Gfi1-null myeloid cells are selectively defective at activating Erk1/2, but not signal transducer and activator of transcription 1 (STAT1) or STAT3, and fail to differentiate into neutrophils. Expression of RasGRP1 in Gfi1-deficient cells rescues Erk1/2 activation by G-CSF and allows neutrophil maturation by G-CSF. These results uncover a previously unknown function of Gfi1 as a regulator of RasGRP1 and link Gfi1 transcriptional control to G-CSF signaling and regulation of granulopoiesis.

Thalidomide decreases gelatinase production by malignant B lymphoid cell lines through disruption of multiple integrin-mediated signaling pathways.

BACKGROUND: Thalidomide and its analogs are effective agents in the treatment of multiple myeloma. Since gelatinases (matrix metalloproteinases-2 and -9) play a crucial role in tumor progression, we explored the effect of thalidomide on gelatinase production by malignant B lymphoid cell lines. DESIGN AND METHODS: We investigated the effect of therapeutic doses of thalidomide on integrin-mediated production of gelatinases by malignant B lymphoid cell lines by gelatin zymography, western-blot, reverse transcriptase polymerase chain reaction and invasive capacity through Matrigel-coated Boyden chambers. We also explored the effect of thalidomide on the activation status of the main signaling pathways involved in this process. RESULTS: Thalidomide strongly inhibited gelatinase production by B-cell lines and primary myeloma cells in response to fibronectin, the most efficient gelatinase inducer identified in lymphoid cells. Thalidomide disrupted integrin-mediated signaling pathways involved in gelatinase induction and release, such as Src and MAP-kinase ERK activation, resulting in decreased cell motility and invasiveness. Unexpectedly, treatment with thalidomide elicited an increase in fibronectin-induced Akt phosphorylation through phosphoinositide 3-kinase-independent pathways since thalidomide decreased fibronectin-induced phosphoinositide 3-kinase phosphorylation and reversed the inhibition of Akt phosphorylation achieved by the phosphoinositide 3-kinase inhibitors wortmannin and LY294002. CONCLUSIONS: Disruption of integrin-mediated signaling may be an important mechanism through which thalidomide and its analogs impair tumor cell interactions with the microenvironment. The unexpected effects of thalidomide on Akt activation indicate the need for further studies to elucidate whether the interference with Akt downstream effects would synergize with the anti-tumor activity of thalidomide.

Dll4 activation of Notch signaling reduces tumor vascularity and inhibits tumor growth.

Gene targeting experiments have shown that Delta-like 4 (Dll4) is a vascular-specific Notch ligand critical to normal vascular development. Recent studies have demonstrated that inhibition of Dll4/Notch signaling in tumor-bearing mice resulted in excessive, yet nonproductive tumor neovascularization and unexpectedly reduced tumor growth. Because nonfunctional blood vessels have the potential to normalize, we explored the alternative approach of stimulating Notch signaling in the tumor vasculature to inhibit tumor growth. Here we show that retrovirus-induced over-expression of Dll4 in tumor cells activates Notch signaling in cocultured endothelial cells and limits vascular endothelial growth factor (VEGF)-induced endothelial cell growth. Tumors produced in mice by injection of human and murine tumor cells transduced with Dll4 were significantly smaller, less vascularized and more hypoxic than controls, and displayed evidence of Notch activation. In addition, tumor blood perfusion was reduced as documented by vascular imaging. These results demonstrate that Notch activation in the tumor microenvironment reduces tumor neovascularization and blood perfusion, and suggest that Dll4-induced Notch activation may represent an effective therapeutic approach for the treatment of solid tumors.

Regulation of CXCR4 by the Notch ligand delta-like 4 in endothelial cells.

Gene-targeting studies have shown that Delta-like 4 (Dll4) is required for normal embryonic vascular remodeling, but the mechanisms underlying Dll4 regulatory functions are not well defined. We generated primary human umbilical vascular endothelial cells that express Dll4 protein to study Dll4 function and previously showed that Dll4 down-regulates vascular endothelial growth factor (VEGF) receptor 2 and NRP1 expression and inhibits VEGF function. We now report that expression of Dll4 in endothelial cells inhibited attachment and migration to stromal-derived growth factor 1 (SDF1) chemokine. Cell surface, total protein, and mRNA levels of CXCR4, principal signaling receptor for SDF1, were significantly decreased in Dll4-transduced endothelial cells, attributable to a significant reduction of CXCR4 promoter activity. An immobilized recombinant extracellular portion of Dll4 (rhDLL4) was sufficient to down-regulate CXCR4 mRNA and protein, whereas protein levels of SDF1, VEGF, and RDC1 were unchanged. The gamma-secretase inhibitor L-685,458 significantly reconstituted CXCR4 mRNA in rhDLL4-stimulated endothelial cells. CXCR4 mRNA levels were significantly reduced in mouse xenografts of Dll4-transduced human gliomas compared with control gliomas, and vascular CXCR4 was not detected by immunohistochemistry in the enlarged vessels within the Dll4 gliomas. Thus, Dll4 may contribute to vascular differentiation and inhibition of the angiogenic response by regulating multiple receptor pathways.

Development of aortic aneurysm/dilatation during the followup of patients with giant cell arteritis: a cross-sectional screening of fifty-four prospectively followed patients.

OBJECTIVE: Giant cell arteritis (GCA) may involve the aorta. Retrospective studies have demonstrated a higher prevalence of aortic aneurysm among patients with GCA compared with the general population. We investigated the prevalence of aortic aneurysm in a cohort of patients with biopsy-proven GCA using a defined protocol and assessed whether persisting low-grade disease activity is associated with higher risk of developing aortic aneurysm. METHODS: Fifty-four patients with GCA (14 men and 40 women) were cross-sectionally evaluated after a median followup of 5.4 years (range 4.0-10.5 years). The screening protocol included a chest radiograph, abdominal ultrasonography scan, and computed tomography scan when aortic aneurysm was suspected or changes with respect to the baseline chest radiograph were observed. Clinical and laboratory data, corticosteroid requirements, and relapses were prospectively recorded. RESULTS: Twelve patients (22.2%) had significant aortic structural damage (aneurysm/dilatation), 5 of them candidates for surgical repair. Aortic aneurysm/dilatation was more frequent among men (50%) than women (12.5%; relative risk 3.5, 95% confidence interval 1.53-8.01, P = 0.007). At the time of screening, patients with aneurysm/dilatation had lower serum acute-phase reactants, lower relapse rate, and needed shorter periods to withdraw prednisone than patients without aortic structural damage. CONCLUSION: There is a substantial risk of developing aortic aneurysm/dilatation among patients with GCA. Our data do not support that aneurysm formation mainly results from persistent detectable disease activity. Additional factors including characteristics of the initial injury or the target tissue may also determine susceptibility to aortic aneurysm/dilatation.

Sulfated polysaccharides identified as inducers of neuropilin-1 internalization and functional inhibition of VEGF165 and semaphorin3A.

Neuropilin-1 (NRP1) and NRP2 are cell surface receptors shared by class 3 semaphorins and vascular endothelial growth factor (VEGF). Ligand interaction with NRPs selects the specific signal transducer, plexins for semaphorins or VEGF receptors for VEGF, and promotes NRP internalization, which effectively shuts down receptor-mediated signaling by a second ligand. Here, we show that the sulfated polysaccharides dextran sulfate and fucoidan, but not others, reduce endothelial cell-surface levels of NRP1, NRP2, and to a lesser extent VEGFR-1 and VEGFR-2, and block the binding and in vitro function of semaphorin3A and VEGF(165). Administration of fucoidan to mice reduces VEGF(165)-induced angiogenesis and tumor neovascularization in vivo. We find that dextran sulfate and fucoidan can bridge the extracellular domain of NRP1 to that of the scavenger receptor expressed by endothelial cells I (SREC-I), and induce NRP1 and SREC-I coordinate internalization and trafficking to the lysosomes. Overexpression of SREC-I in SREC-I-negative cells specifically reduces cell-surface levels of NRP1, indicating that SREC-I mediates NRP1 internalization. These results demonstrate that engineered receptor internalization is an effective strategy for reducing levels and function of cell-surface receptors, and identify certain sulfated polysaccharides as "internalization inducers."

Bone marrow angiogenesis and angiogenic factors in multiple myeloma treated with novel agents.

INTRODUCTION: An increased bone marrow (BM) angiogenesis is associated with poor outcome in multiple myeloma (MM). OBJECTIVE: Angiogenesis study in MM treated with novel antimyeloma agents: thalidomide, lenalidomide, bortezomib, and with dexamethasone. PATIENTS AND METHODS: Forty-four patients with MM (14 newly diagnosed, 30 refractory/relapsed) were treated with novel agents at our institution. A BM biopsy was obtained before the initiation of therapy in 19. Angiogenesis was assessed by microvessel density (MVD) estimation in BM biopsies stained with the monoclonal anti-CD34 antibody, and by serum levels of angiogenic factors (VEGF, bFGF, and HGF) and cytokines (IL-6 and TNF-alpha). RESULTS: A positive correlation was found between BM plasma cell involvement and MVD estimation (p=0.01). However, MVD was not significantly correlated with either disease phase (p=0.065) or response to therapy (p=0.79). Neither baseline serum levels of angiogenic cytokines correlated to response to treatment. No significant correlation was found between BM MVD and serum levels of angiogenic cytokines. Serum levels of angiogenic cytokines before and after therapy showed a significant increase of bFGF (p=0.008). CONCLUSION: There is no relationship between MVD estimation and baseline serum levels of angiogenic cytokines, neither between each of them and response to therapy.

Gelatinase expression and proteolytic activity in giant-cell arteritis.

OBJECTIVES: Gelatinases (MMP2 and MMP9) are expressed in giant-cell arteritis (GCA) and are thought to play a role in vessel disruption. However, their activation status and enzymatic activity have not been evaluated. Our aim was to investigate the distribution and proteolytic activity of gelatinases in GCA lesions at different stages. METHODS: Expression of MMP2, MMP9, MMP2-activator MMP14 and their natural inhibitors TIMP1 and TIMP2 was determined by real-time PCR and immunohistochemistry in temporal artery sections from 46 patients and 12 controls. MMP activation status and enzymatic activity were assessed by gelatin and film in situ zymography. RESULTS: Vascular smooth muscle cells from normal specimens constitutively expressed pro-MMP2 and its inhibitor TIMP2 with no resulting proteolytic activity. In GCA MMP2, MMP9 and MMP14 were strongly expressed in their active form by infiltrating leucocytes. Inflamed arteries also expressed TIMP1 and TIMP2. However, the MMP9/TIMP1 and MMP2/TIMP2 ratios were higher in patients compared with controls, indicating an increased proteolytic balance in GCA which was confirmed by in situ zymography. Maximal gelatinase expression and activity occurred at the granulomatous areas surrounding the internal elastic lamina (IEL). Myointimal cells also expressed MMPs and exhibited proteolytic activity, suggesting a role for gelatinases in vascular remodelling and repair. CONCLUSIONS: GCA lesions show intense expression of gelatinases. Activators and inhibitors are regulated to yield enhanced gelatinase activation and proteolytic activity. Distribution of expression and proteolytic activity suggests that gelatinases have a major role not only in the progression of inflammatory infiltrates and vessel destruction but also in vessel repair.

Noninvasive diagnosis of hepatic fibrosis in HIV/HCV-coinfected patients.

BACKGROUND: Several serum markers reflecting extracellular matrix status have been correlated with liver fibrosis in non-HIV-infected patients with chronic hepatitis C infection. These indexes have been less examined in HIV/HCV-coinfected individuals. OBJECTIVE: We aimed to evaluate the predictive value of serum markers for liver fibrosis in HIV-infected patients with chronic hepatitis C virus (HVC). METHODS: Serum levels of metalloproteinases 1 and 2 (MMP-1 and -2), tissue inhibitors of matrix metalloproteinases (TIMP-1), procollagen type III N-terminal peptide (PIIINP), and hyaluronic acid (HA) were measured in HIV-infected patients with chronic hepatitis C at the time of obtaining a liver biopsy and before the consideration of anti-hepatitis C therapy. RESULTS: One hundred and nineteen consecutive HIV-HVC coinfected patients were included. TIMP-1 (r = 0.6; P < 0.001), TIMP-1/MMP-1 ratio (r = 0.5; P < 0.001), TIMP-1/MMP-2 ratio (r = 0.3; P < 0.001), MMP-2 (r = 0.2; P = 0.044), PIIINP (r = 0.4; P < 0.001), and HA (r = 0.5; P < 0.001) were positively and significantly correlated with the fibrosis stage. In the multivariate analysis, TIMP-1 (odds ratio [OR] = 1.004, 95% confidence interval [CI]: 1.002 to 1.006, P = 0.001) and HA >95 microg/dL (OR = 6.041, 95% CI: 1.184 to 30.816, P = 0.031) were independently associated with liver fibrosis. The area under the curve of score to discriminate mild (F0-F1) from significant (F2-F4) fibrosis in the received-operating analysis using the variables TIMP-1 and HA was 0.84, with a sensitivity of 72.9% and a specificity of 83.1%. CONCLUSION: TIMP-1 and HA were quite sensitive and specific for predicting the degree of liver fibrosis in HIV-infected patients with chronic hepatitis C. These parameters may become a noninvasive alternative to liver biopsy when the degree of liver fibrosis needs to be estimated.

Increased levels of atherosclerosis markers in salt-sensitive hypertension.

BACKGROUND: Salt sensitivity in essential hypertension is associated with both endothelial dysfunction and increased cardiovascular risk. We evaluated several serum markers of atherosclerosis and endothelial function in a group of essential hypertensive patients classified on the basis of their salt sensitivity. METHODS: Forty-three patients were classified as having salt-sensitive (20 subjects) or salt-resistant (23 subjects) hypertension on the basis of their 24-h blood pressure (BP) response from low salt (50 mmol/d) to high salt (250 mmol/d) intake. Endothelium-dependent and independent responses were measured in the forearm previously to salt manipulation. High-sensitivity C-reactive protein (CRP), soluble intercellular adhesion molecule type 1 (sICAM-1), soluble vascular cell adhesion molecule type 1 (sVCAM-1), e-selectin, p-selectin, interleukin-6 (IL-6), monocyte chemotactic protein type 1 (MCP-1), matrix metalloproteinases types 1, 2, and 9 (MMP-1, MMP-2, and MMP-9), and the tissue inhibitor of metalloproteinases type 1 (TIMP-1) were measured in serum on the last day of both low salt and high salt intakes. RESULTS: Compared to salt-resistant patients, salt-sensitive hypertensives showed age-adjusted increased levels of p-selectin (P = .006), e-selectin (P = .042), and MCP-1 (P = .036), although differences in e-selectin were not maintained after adjustment for BP values. Moreover, salt-sensitive subjects exhibited decreased serum levels of MMP-9 (P = .007) and increased levels of TIMP-1 (P = .045). No differences in serum CRP, sICAM-1, sVCAM-1, or IL-6 were observed between salt-sensitive and salt-resistant patients. Finally, maximal acetylcholine-induced vasodilation (319% +/- 153% v 414% +/- 178% increase in forearm blood flow; P = .022 age-adjusted) was significantly impaired in salt-sensitive hypertensives. CONCLUSIONS: Serum markers of inflammation, especially selectins and chemokines, as well as markers of vascular remodeling, and endothelium-dependent vasodilation are altered in salt-sensitive hypertension. These alterations could help to explain the greater target organ damage and cardiovascular risk observed in salt-sensitive subjects.