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C D Figueroa

Publications and source records attributed to C D Figueroa.

At least 19 recordsLinked to original sources
PubMed2006

Activation of kinin B1 receptors induces chemotaxis of human neutrophils.

Kinins are biologically active peptides that are powerful mediators of cellular inflammation. They mimic the cardinal signs of inflammation by inducing vasodilatation and by increasing vascular permeability and pain. Neutrophils are chemoattracted to sites of inflammation by several stimuli. However, the evidence concerning the chemotactic effect of kinin peptides has been contradictory. We analyzed the chemotactic effect of kinin B(1) receptor agonists on neutrophils isolated from peripheral blood of human healthy subjects. Chemotaxis was performed using the migration under agarose technique. To test the effect of B(1) receptor agonists, each assay was carried out overnight at 37 degrees C in 5% CO(2)-95% air on neutrophils primed with 1 ng/ml interleukin-1beta. Simultaneous experiments were performed using unprimed cells or cells challenged with formyl-Met-Leu-Phe (fMLP). A clear chemotactic activity was observed when primed neutrophils were challenged with Lys-des[Arg(9)]-bradykinin (LDBK) or des[Arg(9)]-bradykinin at 10(-10) M but not when unprimed cells were used. A reduction in the chemotactic response was observed after priming of cells in the presence of 0.5 mM cycloheximide and 10 mug/ml brefeldin A, suggesting that some protein biosynthesis is required. Techniques such as reverse transcriptase-polymerase chain reaction and in situ hybridization confirmed the expression of the B(1) receptor mRNA, and immunocytochemistry and autoradiography demonstrated the expression of the B(1) receptor protein. In contrast to other chemoattractants such as fMLP, cytosolic intracellular calcium did not increase in response to the B(1) receptor agonist LDBK. A generation of kinin B(1) receptor agonists during the early phase of acute inflammation may favor the recruitment of neutrophils to the inflammatory site.

Binding Sites↗
PubMed2006

Modulation of renal kallikrein by a high potassium diet in rats with intense proteinuria.

Injury of the renal tubulointerstitial compartment is recognized to play an important role in hypertension. Its damage may in turn, impair the activity of vasodepressor systems, like the kallikrein-kinin, in blood pressure regulation. The overload proteinuria model induces tubulointerstitial injury with activation of the renin-angiotensin system, but renal kallikrein and the development of hypertension have not received special attention. Sprague-Dawley rats received seven intraperitoneal doses of bovine serum albumin (BSA) 2 g/day under normosodic diet and were hydrated ad libitum. A second group received a high potassium diet to stimulate kallikrein production during the previous four weeks and while under BSA administration. A third one received potassium and BSA in the same schedule, but with the kinin B2 receptor antagonist, HOE140, added during the protein load phase. A control group received seven saline injections. Kallikrein protein was detected by immune labeling on renal sections and enzymatic activity in the urine. The BSA group showed massive proteinuria followed by intense tubulointerstitial damage. Blood pressure increased after the third dose in BSA animals, remaining elevated throughout the experiment, associated with significant reductions in renal expression and urinary activity of kallikrein, compared with controls. An inverse correlation was found between blood pressure and immunohistochemistry and urinary activity of kallikrein. Potassium induced a significant increase in both urinary activity and renal kallikrein expression, associated with significant reduction in blood pressure. The HOE140 antagonist blunted the antihypertensive effect of kallikrein stimulation in proteinuric rats. Loss of renal kallikrein, produced by tubulointerstitial injury, may participate in the pathogenesis of the hypertension observed in this model.

Animals↗
PubMed2004

Nerve growth factor promotes reparative angiogenesis and inhibits endothelial apoptosis in cutaneous wounds of Type 1 diabetic mice.

AIMS/HYPOTHESIS: The neurotrophin nerve growth factor (NGF) is pro-angiogenic and facilitates wound repair. The present study was conducted to (i) assess the statement of NGF system components in diabetic wounds and (ii) evaluate whether NGF supplementation could prevent impairment of wound neoangiogenesis by diabetes. METHODS: Skin wounds were produced in the interscapular region of streptozotocin-induced diabetic mice. NGF (1 microg per day in PBS) or vehicle was applied onto the ulcers for 3 days after punching. Non-diabetic mice were used as controls. RESULTS: In wounds of untreated diabetic mice, endogenous levels of immunoreactive NGF were lower than those in wounds of non-diabetic mice ( p<0.01). Immunohistochemical analysis showed down-regulation of tyrosine kinase receptor-A (TrkA) and up-regulation of p75 receptor in granulation tissue microvasculature. Local NFG administration prevented diabetes-induced expressional alterations, enhanced reparative capillarisation ( p<0.01), and accelerated wound closure ( p<0.01). This was associated with a three-fold increase in endothelial cell proliferation ( p<0.01), while apoptosis was reduced by 50% ( p<0.05). Quantitative RT-PCR documented a 5.5-fold increase in the expression of vascular endothelial growth factor-A (VEGF-A) by exogenous NGF in diabetic tissues ( p<0.01). In in vitro preparations of human endothelial cells from derma, NGF increased the release of immunoreactive VEGF-A, and reduced high-glucose-induced apoptosis ( p<0.05), the latter effect being inhibited by a VEGF-A receptor-2 antagonist. CONCLUSIONS/INTERPRETATION: Diabetic ulcers display distinct alterations in reparative angiogenesis and in the expression of NGF and its receptors. NGF supplementation corrects endogenous liabilities, facilitates vascular regeneration, and suppresses endothelial apoptosis seemingly via VEGF-A. Our findings unravel new mechanisms responsible for NGF reparative action.

Administration, Cutaneous↗
PubMed2003

Evidence for modulation of human epidermal differentiation and remodelling by CD40.

BACKGROUND: It is widely accepted that CD40 plays a critical role in the regulation of immune response. However, the significance of CD40 expression on normal human keratinocytes is only partially known. OBJECTIVES: To perform a morphological re-examination of the role of CD40 on the differentiation of human keratinocytes and remodelling of the epidermis. METHODS: Keratinocytes were grown on fibroblasts transfected with the CD40 ligand (CD40L) to investigate the formation of epidermal sheets in culture under the influence of the CD40L. Control experiments were carried out using the same cells but transfected with CD32. Further, three specific anti-CD40 monoclonal antibodies were used as soluble agonists to analyse the effect of CD40 ligation on keratinocyte differentiation. RESULTS: Epidermal sheets developing from keratinocytes cocultured with fibroblasts transfected with CD40L but not with CD32 showed an up to 50% reduction in thickness compared with control sheets. This change depended mostly on cellular flattening and a decrease in the number of cell layers, and was coincident with a transient decrease in cell surface CD40 immunoreactivity. On the other hand, normal epidermis, and freshly isolated and cultured keratinocytes revealed a predominant CD40+/Ki-67- phenotype that was demonstrated by double immunocytochemistry. Consistent with these observations, keratinocytes primed with interferon-gamma responded to the three soluble agonists, but not to control IgG1, producing immunoreactive (pro)filaggrin and displaying morphological changes in shape and size equivalent to those seen in differentiated cells. CONCLUSIONS: As a whole, our findings provide evidence that CD40+ keratinocytes represent a poorly differentiated population, not actively engaged in the cell cycle, which under specific stimulation is committed towards terminal differentiation.

Antibodies, Monoclonal↗
PubMed2001

Expression and colocalization of cytokeratin 1 and urokinase plasminogen activator receptor on endothelial cells.

The cellular localization of human cytokeratin 1 (CK1), urokinase plasminogen activator receptor (uPAR), and gC1qR, high-molecular-weight kininogen (HK)-binding proteins on endothelial cells, was determined. CK1 was found on the external membrane of nonpermeabilized endothelial cells by immunoperoxidase staining, immunofluorescence, and transmission electron microscopy using immunogold. Human umbilical vein endothelial cells (HUVECs) had 7.2 +/- 0.2 x 10(4) specific CK1 membrane sites/cell by (125)I-F(ab')(2) anti-CK1 antibody binding. Flow cytometry studies confirmed the presence of CK1, uPAR, and gC1qR on HUVECs. On laser scanning confocal microscopy and transmission electron microscopy, CK1 and uPAR, but not gC1qR, colocalized on the cell surface of HUVECs. The HUVEC surface distribution of these proteins was distinctly different from that for von Willebrand factor. In competitive inhibition experiments, anti-CK1, anti-uPAR, or anti-gC1qR blocked both biotin-HK binding and prekallikrein (PK) activation on HUVECs with an inhibitory concentration of 50% (IC(50)) of 300 to 350 nM, 50 to 60 nM, or 35 to 100 nM, respectively. Also, antibodies to uPAR and gC1qR each inhibited 86% of kallikrein-mediated, 2-chain urokinase plasminogen activation, whereas antibodies to CK1 only inhibited 24% of plasminogen activation. On HUVECs, CK1 and uPAR, but not gC1qR, colocalized to be a multiprotein receptor complex for HK binding, PK activation, and 2-chain urokinase plasminogen activation.

Amino Acid Sequence↗
PubMed2001

Temporospatial changes of kinin b2 receptors during the estrous cycle and pregnancy in the rat uterus.

Tissue kallikreins are present in rat uterus during the estrous cycle in luminal and glandular epithelium, in early gestation in the implantation node, and in the last third of pregnancy surrounding the sinusoids in the decidua basalis. The pattern of kinin B2 receptor expression, through which the vasoactive effect of kallikreins is exerted, was studied by in vitro autoradiography and immunohistochemistry. The kinin B2 receptor was observed in the luminal and glandular epithelium, myometrium, endothelial cells of arteries, veins and venules, and smooth muscle cells of endometrial and myometrial arterioles. Immunoblotting of crude membranes revealed a band of 69 kDa that increased in late proestrus and estrus, concordantly with the pattern of immunostaining observed in the tissue. At Day 7 of gestation, the kinin B2 receptor was expressed (binding sites and receptor protein) in the epithelium of the implantation node and decidual cells; these latter cells showed a further increase during gestational Days 9 and 10. From Days 14 to 21, the subplacental decidua became strongly immunoreactive, and on Days 16 and 21 the placental labyrinthine endothelium was intensely stained. During this period, endothelium of arteries and veins, smooth muscular cells of small diameter arterioles, and myometrium also expressed B2 receptors. In unilaterally oil-stimulated pseudopregnancy, the decidual cells and the glandular epithelium show similar immunoreactivity to that during pregnancy. The temporospatial pattern of kinin B2 receptors, coinciding with that of kallikrein or with sites accessible to the generated kinins, further supports an autocrine-paracrine role for the kallikrein-kinin system in the vasoactive changes of implantation and placental blood flow regulation.

Animals↗
PubMed2001

Tissue kallikrein in human placenta in early and late gestation.

This study was addressed to identify kallikrein mRNA and protein in early, preterm, and term human placenta and to evaluate their temporospatial pattern. Kallikrein mRNA was expressed in syncytio/cytotrophoblasts and in the endothelial cells of the floating villi, with a greater intensity in early samples (isolated spontaneous abortions and ectopic pregnancies). Cytotrophoblasts at the base of the anchoring villi, maternal decidua and decidual arteries, endothelial cells of chorionic and basal plate blood vessels, and the amniotic epithelium presented a positive signal. Tissue kallikrein was predominantly observed in syncytiotrophoblasts and had a greater immunoreactivity in first-trimester samples. Intraarterial trophoblasts, blood vessels of the floating villi, basal and chorionic plates, and the amniotic epithelium showed positive immunoreactivity. The sites and variations of the tissue kallikrein mRNA and protein in the human placenta, in different stages of pregnancy, support the hypothesis that this enzyme may participate in the establishment and maintenance of placental blood flow through vasodilation, platelet antiaggregation, cell proliferation, and trophoblast invasion.

Abortion, Spontaneous↗
PubMed2001

Tissue kallikrein and bradykinin B2 receptor in human uterus in luteal phase and in early and late gestation.

This study was addressed to evaluate the temporospatial pattern of key components of the kallikreinkinin system in human uterus in luteal phase (n = 7), early pregnancy (isolated spontaneous abortions, n = 11; ectopic pregnancies, n = 9), idiopathic preterm deliveries (n = 5), and term gestations (n = 12). Tissue kallikrein mRNA and protein and the type 2 bradykinin receptor (B2R) protein were expressed in luminal and glandular epithelium and in endothelial cells of stromal and myometrial blood vessels, while tissue kallikrein mRNA and B2R, but not tissue kallikrein protein, were observed in decidual cells and in arteriolar and myometrial muscle. A greater signal intensity for tissue kallikrein mRNA and protein and of B2R protein was observed in the early pregnancy samples. The sites and variations of the tissue kallikrein mRNA and protein and of the B2R protein in the human uterus and in fallopian tubes during the luteal phase and in pregnancy coincide with those described for other vasoactive effectors such as nitric oxide, prostacyclins, growth factors, and renin. The uterine localization of the main enzyme and receptor of the tissue kallikrein-kinin system in key sites for embryo attachment, implantation, placentation, maintenance of placental blood flow, and parturition supports the notion that the kallikreinkinin system participates in these processes, probably through vasodilation, increased vasopermeability, enhanced matrix degradation, stimulation of cell proliferation, and myometrial contractility.

Adult↗
PubMed1999

Vasopressin stimulates tyrosine phosphorylation by activation of PKC in the rat smooth muscle cell line, A-10.

Arginine vasopressin (AVP)-induced tyrosine phosphorylation was studied in a rat smooth muscle cell line, A-10, by western blotting, using a monoclonal antibody against phosphotyrosine. AVP stimulated the phosphorylation of several cellular proteins of molecular mass 60-130 kDa in a time- and dose-dependent manner. Phosphorylation was mediated largely by V(1)receptor subtype since it was inhibited by selective V(1)antagonist and was only partially elicited by the V(2)agonist, desmopressin. Heterotrimeric G-proteins seemed to be involved in the phosphorylation mechanism because fluoraluminates, an activator of heterotrimeric G-proteins (and thus an uncoupler of the receptor-G-protein interaction) inhibited the AVP-induced phosphorylation. The protein kinase C (PKC) inhibitors: staurosporine, H7 and GF109203X are able to block the AVP-stimulated phosphorylation. The last of these has been shown to be one of the most selective inhibitors of PKC. These results indicate that PKC is upstream of the phosphorylation, a motion which is supported by the fact that the AVP-stimulated phosphorylation was downregulated by phorbol esters.

Animals↗
PubMed1999

Hydrolysis of kininogens by degranulated human neutrophils and analysis of bradykinin as chemotactic factor for cells isolated from peripheral blood.

Human neutrophils play a pivotal role in acute inflammation including the regulation of vascular permeability. We have examined the capacity of neutrophil enzymes to hydrolyse human kininogens in vitro and have also explored the potentiality of bradykinin to induce chemotactic migration on neutrophils isolated from peripheral blood. Isolated neutrophils were stimulated with either f-Met-Leu-Phe, thrombin or silica particles coated with human IgG. Neutrophil enzymes obtained by degranulation produced, after 45 min of incubation with high and low molecular weight kininogens, the complete transformation of both proteins in polypeptides ranging from 20 to less than 10 kDa in molecular mass. Supernatants obtained from nonstimulated neutrophils did not modify the molecular size of kininogens. The assay used to test the chemoattractant capacity of synthetic bradykinin on human neutrophils showed that this peptide has no chemotactic activity on cells isolated from healthy subjects. Our results show that stimulation of human neutrophils with opsonized silica, thrombin and the chemotactic peptide f-Met-Leu-Phe induces release of kininogen-hydrolyzing enzymes from these cells.

Bradykinin↗
PubMed1999

Vasopressin and bradykinin receptors in the kidney: implications for tubular function.

Vasopressin and bradykinin are two of the most important peptides in regulating vascular tone, water, and ionic balance in the body, and thus they play a key role in controlling blood pressure. In addition to being a potent vasoconstrictor, Vasopressin also has an antidiuretic activity in the kidney, whereas kinins regulate renal blood flow in addition to their vasodilatory and natriuretic activity. We review here the primary evidence for the localization of the vasopressin and kinin receptors and their role in ionic and water regulation in the kidney.

Animals↗
PubMed1998

Autoradiographic and immunological techniques to analyse kinin receptor distribution in rat and human tissues.

Kinins are vasoactive peptides that have traditionally been associated with vascular tone regulation. Nevertheless, the availability of adequate probes directed to kinin receptors has resulted in the identification of these proteins in organs and cells outside the cardiovascular system. The sensitivity, specificity and simplicity of the techniques developed to visualize kinin receptors have allowed the identification of the specific cells that express these receptors under physiological conditions and the investigation of the possible modifications that they may undergo during the onset and development of experimentally induced or diseased-related pathological conditions.

Animals↗
PubMed1998

The kallikrein-kinin system along the different stages of gestation: experimental and clinical findings.

We analyse the data accumulated on the description of the uterine kallikrein-kinin system in estrous cycle, pregnancy, pseudopregnancy and hormonal supplementation, and discuss the possible role of these findings in relationship to the vasoactive changes of gestation. We conclude that the evidence supports a participation of kallikrein in implantation and maintenance of uteroplacental blood flow. A decreased urinary kallikrein in women in conditions of an impaired uterine blood flow might be related to a deficient response of this vasodilator system.

Animals↗
PubMed1997

Ontogeny of bradykinin B2 receptors in the rat kidney: implications for segmental nephron maturation.

Kinins modulate renal function, yet their role in the developing kidney is largely unknown. To explore the developmental role of the kallikrein-kinin system, we examined the postnatal ontogeny and intrarenal localization of B2 receptors in the rat. Northern blot analysis and RT-PCR documented the expression of B2 receptor mRNA in the kidney and extrarenal tissues of fetal, neonatal and adult animals. The abundance of B2 receptor mRNA is 10- to 30-fold higher in neonatal than adult tissues in the following order: kidney > heart > aorta > lung > brain. Receptor autoradiography revealed a gradual shift in the localization of bradykinin binding sites from the outer cortex in the newborn to the outer medulla in weanling and maturing rats. The almost complete displacement of [125I]tyr(zero)-bradykinin by HOE-140 indicates that the majority of kinin receptors in the developing kidney belong to the B2 type. Immunolocalization studies using antipeptide antibodies directed against various portions of the receptor revealed that B2 receptors are first expressed on the luminal aspect of the upper limb of S-shaped bodies and differentiating cortical collecting ducts. In marked contrast, the metanephric mesenchyme, pretubular aggregates and glomeruli display weak or no B2 receptor immunoreactivity. Following completion of nephrogenesis, B2 receptor expression shifts to both luminal and basolateral aspects of connecting tubules and collecting ducts. The results demonstrate that bradykinin B2 receptor gene expression is activated in the developing kidney and cardiovascular system. The spatially restricted expression of B2 receptors in the differentiating epithelium of the distal nephron, the site of kinin formation, supports the hypothesis that kinins are paracrine modulators of segmental nephron maturation.

Amino Acid Sequence↗
PubMed1997

Immunolocalization of V1 vasopressin receptors in the rat kidney using anti-receptor antibodies.

By using immunocytochemical techniques we have been able to localize the V1 vasopressin receptor in the rat kidney. Immunoblotting using an antiserum raised against an affinity-purified vasopressin receptor showed a 55,000 daltons protein band that has a molecular mass similar to that of the liver V1 vasopressin receptor, as demonstrated by cross-linking studies. Immunoblotting of the antibody showed a band of 55,000 daltons in A-10 cells, which contains the V1 subtype, whereas it did not stain LLC-PK1 cells, which possess the V2 subtype, showing that the antibody recognizes the V1 vasopressin receptor. The immunostaining of kidney sections with this antiserum showed a strong reaction of the connecting tubules and cortical and medullary collecting ducts. The immunostaining pattern of connecting tubule and collecting duct cells was different, that is, the former showed a staining of both the apical and basal plasma membrane but also in the cytoplasm, whereas the latter showed a strong reaction mainly in the basolateral membrane. Immunostaining of consecutive serial sections with an antiserum raised against tissue kallikrein, an enzyme present exclusively in connecting tubules, and with the anti-receptor serum allowed us to show, for the first time, the presence of the vasopressin receptor in the connecting tubule cells and their absence in intercalated cells, the other cell type present in connecting tubules. These findings support experiments carried in the eighties on the release of renal tissue kallikrein by AVP.

Animals↗
PubMed1996

Localization of the fructose 1,6-bisphosphatase at the nuclear periphery.

The localization of fructose 1,6-bisphosphatase (D-Fru-1,6-)2-1-phosphohydrolase, EC 3.1.3.11) in rat kidney and liver was determined immunohistochemically using a polyclonal antibody raised against the enzyme purified from pig kidney. The immunohistochemical analysis revealed that the bisphosphatase was preferentially localized in hepatocytes of the periportal region of the liver and was absent from the perivenous region. Fructose-1,6-bisphosphatase was also preferentially localized in the cortex of the kidney proximal tubules and was absent in the glomeruli, loops of Henle, collecting and distal tubules, and in the renal medulla. As indicated by immunocytochemistry using light microscopy and confirmed with the use of reflection confocal microscopy, the enzyme was preferentially localized in a perinuclear position in the liver and the renal cells. Subcellular fractionation studies followed by enzyme activity assays revealed that a majority of the cellular fructose-1,6-bisphosphatase activity was associated to subcellular particulate structures. Overall, the data support the concept of metabolic zonation in liver as well as in kidney, and establish the concept that the Fructose-1,6-bisphosphatase is a particulate enzyme that can not be considered a soluble enzyme in the classical sense.

Animals↗