Lactose and Casein Cause Changes on Biomarkers of Oxidative Damage and Dysbiosis in an Experimental Model of Multiple Sclerosis.

BACKGROUND AND OBJECTIVES: Experimental Autoimmune Encephalomyelitis (EAE) in rats closely reproduces Multiple Sclerosis (MS), a disease characterized by neuroinflammation and oxidative stress that also appears to extend to other organs and their compartments. The origin of MS is a matter for discussion, but it would seem that altering certain bacterial populations present in the gut may lead to a proinflammatory condition due to the bacterial Lipopolysaccharides (LPS) in the so-called brain-gut axis. The casein and lactose in milk confer anti-inflammatory properties and immunomodulatory effects. The objectives of this study were to evaluate the effects of administration of casein and lactose on the oxidative damage and the clinical status caused by EAE and to verify whether both casein and lactose had any effect on the LPS and its transport protein -LBP-. METHODS: Twenty male Dark Agouti rats were divided into control rats (control), EAE rats, and EAE rats, to which casein and lactose, EAE+casein, and EAE+lactose, respectively, were administered. Fifty-one days after casein and lactose administration, the rats were sacrificed, and different organs were studied (brain, spinal cord, blood, heart, liver, kidney, small, and large intestine). In the latter, products derived from oxidative stress were studied (lipid peroxides and carbonylated proteins) as well as the glutathione redox system, various inflammation factors (total nitrite, Nuclear Factor-kappa B p65, the Rat Tumour Necrosis Factor-α), and the LPS and LBP values. RESULTS AND CONCLUSION: Casein and lactose administration improved the clinical aspect of the disease at the same time as reducing inflammation and oxidative stress, exerting its action on the glutathione redox system, or increasing GPx levels.

Microvesicles Derived from Indoxyl Sulfate Treated Endothelial Cells Induce Endothelial Progenitor Cells Dysfunction.

Cardiovascular disease is a major cause of mortality in chronic kidney disease patients. Indoxyl sulfate (IS) is a typical protein-bound uremic toxin that cannot be effectively cleared by conventional dialysis. Increased IS is associated with the progression of chronic kidney disease and development of cardiovascular disease. After endothelial activation by IS, cells release endothelial microvesicles (EMV) that can induce endothelial dysfunction. We developed an in vitro model of endothelial damage mediated by IS to evaluate the functional effect of EMV on the endothelial repair process developed by endothelial progenitor cells (EPCs). EMV derived from IS-treated endothelial cells were isolated by ultracentrifugation and characterized for miRNAs content. The effects of EMV on healthy EPCs in culture were studied. We observed that IS activates endothelial cells and the generated microvesicles (IsEMV) can modulate the classic endothelial roles of progenitor cells as colony forming units and form new vessels in vitro. Moreover, 23 miRNAs were contained in IsEMV including four (miR-181a-5p, miR-4454, miR-150-5p, and hsa-let-7i-5p) that were upregulated in IsEMV compared with control endothelial microvesicles. Other authors have found that miR-181a-5p, miR-4454, and miR-150-5p are involved in promoting inflammation, apoptosis, and cellular senescence. Interestingly, we observed an increase in NFκB and p53, and a decrease in IκBα in EPCs treated with IsEMV. Our data suggest that IS is capable of inducing endothelial vesiculation with different membrane characteristics, miRNAs and other molecules, which makes maintaining of vascular homeostasis of EPCs not fully functional. These specific characteristics of EMV could be used as novel biomarkers for diagnosis and prognosis of vascular disease.

Dietary magnesium supplementation prevents and reverses vascular and soft tissue calcifications in uremic rats.

Although magnesium has been shown to prevent vascular calcification in vitro, controlled in vivo studies in uremic animal models are limited. To determine whether dietary magnesium supplementation protects against the development of vascular calcification, 5/6 nephrectomized Wistar rats were fed diets with different magnesium content increasing from 0.1 to 1.1%. In one study we analyzed bone specimens from rats fed 0.1%, 0.3%, and 0.6% magnesium diets, and in another study we evaluated the effect of intraperitoneal magnesium on vascular calcification in 5/6 nephrectomized rats. The effects of magnesium on established vascular calcification were also evaluated in uremic rats fed on diets with either normal (0.1%) or moderately increased magnesium (0.6%) content. The increase in dietary magnesium resulted in a marked reduction in vascular calcification, together with improved mineral metabolism and renal function. Moderately elevated dietary magnesium (0.3%), but not high dietary magnesium (0.6%), improved bone homeostasis as compared to basal dietary magnesium (0.1%). Results of our study also suggested that the protective effect of magnesium on vascular calcification was not limited to its action as an intestinal phosphate binder since magnesium administered intraperitoneally also decreased vascular calcification. Oral magnesium supplementation also reduced blood pressure in uremic rats, and in vitro medium magnesium decreased BMP-2 and p65-NF-κB in TNF-α-treated human umbilical vein endothelial cells. Finally, in uremic rats with established vascular calcification, increasing dietary magnesium from 0.1% magnesium to 0.6% reduced the mortality rate from 52% to 28%, which was associated with reduced vascular calcification. Thus, increasing dietary magnesium reduced both vascular calcification and mortality in uremic rats.

Markers of endothelial damage in patients with chronic kidney disease on hemodialysis.

Patients with Stage 5 chronic kidney disease who are on hemodialysis (HD) remain in a chronic inflammatory state, characterized by the accumulation of uremic toxins that induce endothelial damage and cardiovascular disease (CVD). Our aim was to examine microvesicles (MVs), monocyte subpopulations, and angiopoietins (Ang) to identify prognostic markers in HD patients with or without diabetes mellitus (DM). A total of 160 prevalent HD patients from 10 centers across Spain were obtained from the Biobank of the Nephrology Renal Network (Madrid, Spain): 80 patients with DM and 80 patients without DM who were matched for clinical and demographic criteria. MVs from plasma and several monocyte subpopulations (CD142+/CD16+, CD14+/CD162+) were analyzed by flow cytometry, and the plasma concentrations of Ang1 and Ang2 were quantified by ELISA. Data on CVD were gathered over the 5.5 yr after these samples were obtained. MV level, monocyte subpopulations (CD14+/CD162+ and CD142+/CD16+), and Ang2-to-Ang1 ratios increased in HD patients with DM compared with non-DM patients. Moreover, MV level above the median (264 MVs/µl) was associated independently with greater mortality. MVs, monocyte subpopulations, and Ang2-to-Ang1 ratio can be used as predictors for CVD. In addition, MV level has a potential predictive value in the prevention of CVD in HD patients. These parameters undergo more extensive changes in patients with DM.

Hemodiafiltration With Endogenous Reinfusion Improved Microinflammation and Endothelial Damage Compared With Online-Hemodiafiltration: A Hypothesis Generating Study.

Hemodiafiltration with endogenous reinfusion (HFR) after ultrafiltrate passage through a resin cartridge combines adsorption, convection, and diffusion. Our prospective single-center crossover study compared HFR and online-hemodiafiltration (OLHDF) effects on two uremic toxins and 13 inflammatory, endothelial status, or oxidative stress markers. After an 8-week run-in period of high-flux hemodialysis, 17 eligible stable dialysis patients (median age 65 years, 10 male) without overt clinical inflammation were scheduled for four 8-week periods in the sequence: HFR/OLHDF/HFR/OLHDF. Relative to OLHDF, HFR was associated with greater indoxyl sulfate removal and lesser abnormalities in all other study variables, namely circulating interleukin-6, tumor necrosis factor-alpha, proportions of activated proinflammatory (CD14+CD16+, CD14++CD16+) monocytes, endothelial progenitor cells, apoptotic endothelial microparticles, vascular endothelial growth factor, vascular cellular adhesion molecule, angiopoietins 2 and 1, annexin V, and superoxide dismutase. Differences were significant (P < 0.05) in median values of 13/15 variables. Study period comparisons were generally consistent with dialysis technique comparisons, as were data from the subgroup completing all study periods (n = 9). Our investigation provides hypothesis-generating results suggesting that compared with OLHDF, HFR improves protein-bound toxin removal, inflammatory and endothelial status, and oxidative stress.

Klotho Prevents NFκB Translocation and Protects Endothelial Cell From Senescence Induced by Uremia.

In patients with renal disease, uremia raises oxidative stress and senescence in endothelial cells, which can lead to endothelial dysfunction and cardiovascular disease. Klotho protein is a ß-glucuronidase capable of hydrolyzing steroid ß-glucuronides. This protein is recognized as an antiaging gene, that modulate both stress-induced senescence and functional response. The aim of the study was to investigate how senescence and oxidative stress induced by uremia in endothelial cells affects Klotho expression and whether intra or extracellular Klotho has effects on the response of these cells. Senescence and oxidative stress was obtained by exposure to uremic serum. Telomere length, the enzyme ß-galactosidase, and oxidative stress were studied by flow cytometry. Nuclear factor kappa B activity was determined by electrophoretic mobility shift assay. The expression of Klotho decreased with the uremia and preceded the manifestations of cell aging. Levels of intracellular Klotho decreases associated to endothelial senescence, and exogenous Klotho prevents cellular senescence by inhibiting the increase in oxidative stress induced by uremia and diminished the nuclear factor kappa B-DNA binding ability.

Endothelial microparticles mediate inflammation-induced vascular calcification.

Stimulation of endothelial cells (ECs) with TNF-α causes an increase in the expression of bone morphogenetic protein-2 (BMP-2) and the production of endothelial microparticles (EMPs). BMP-2 is known to produce osteogenic differentiation of vascular smooth muscle cells (VSMCs). It was found that EMPs from TNF-α-stimulated endothelial cells (HUVECs) contained a significant amount of BMP-2 and were able to enhance VSMC osteogenesis and calcification. Calcium content was greater in VSMCs exposed to EMPs from TNF-α-treated HUVECs than EMPs from nontreated HUVECs (3.56 ± 0.57 vs. 1.48 ± 0.56 µg/mg protein; P < 0.05). The increase in calcification was accompanied by up-regulation of Cbfa1 (osteogenic transcription factor) and down-regulation of SM22α (VSMC lineage marker). Inhibition of BMP-2 by small interfering RNA reduced the VSMC calcification induced by EMPs from TNF-α-treated HUVECs. Similar osteogenic capability was observed in EMPs from both patients with chronic kidney disease and senescent cells, which also presented a high level of BMP-2 expression. Labeling of EMPs with CellTracker shows that EMPs are phagocytized by VSMCs under all conditions (with or without high phosphate, control, and EMPs from TNF-α-treated HUVECs). Our data suggest that EC damage results in the release of EMPs with a high content of calcium and BMP-2 that are able to induce calcification and osteogenic differentiation of VSMCs.

Cellular senescence determines endothelial cell damage induced by uremia.

Renal dysfunction is closely associated with endothelial damage leading to cardiovascular disease. However, the extent to which endothelial damage induced by uremia is modulated by aging is poorly known. Aging can render endothelial cells more susceptible to apoptosis through an oxidative stress-dependent pathway. We examined whether senescence-associated to oxidative stress determines the injury induced by the uremia in endothelial cells. Human umbilical vein endothelial cells (HUVEC) was incubated with human uremic serum and, in the animal model, endothelial cells were obtained from aortas of uremic and no uremic rats. Vitamin C was used to prevent oxidative stress. Senescence, assessed by telomere length and enzyme-betagalactosidase (ß-gal), reactive oxygen species (ROS), mitochondrial depolarization (JC-1 probe), caspase 3, and apoptosis were determined by flow cytometry. NF-κB activity was determined by Western blot. Uremic serum increased ROS and NF-κB in young and aging HUVEC. However only in aging cells, uremic serum induced apoptosis (vs young HUVEC, p<0.01). The endothelial damage induced by uremia seems to be related with the increased oxidative stress, since in both HUVEC and in the experimental model of renal disease in rats, vitamin C prevents endothelial apoptosis. However, vitamin C did not decrease the oxidative stress associated to senescence. These results showed that as compared with young cells, senescent cells have high sensitivity to damage associated to the oxidative stress induced by the uremia. Consequently, protecting senescent endothelial cells from increased oxidative stress might be an effective therapeutic approach in the treatment of vascular disorders in chronic kidney diseases.

Klotho modulates the stress response in human senescent endothelial cells.

Lack of Klotho expression in mice leads to premature aging and age-related diseases, including vascular diseases. The aim of this study was to determine how endothelial cell line senescence affects Klotho expression and whether intra- or extracellular Klotho has any effect on the response of senescent cells to oxidative stress. The study was performed using human endothelial cells (HUVEC); cell aging was obtained by prolongation of cell division to 42 population doublings (PD). Senescence was also obtained by exposure to TNFα, which causes cell changes resembling cellular senescence. The decline in Klotho preceded the manifestations of cell ageing: telomere shortening and ß-galactosidase expression. Klotho was also reduced in cells exposed to the proinflammatory cytokine TNFα. The addition of exogenous Klotho to aging cells did not modify the proportion of cells with short telomeres or any other feature of cell aging; however, exogenous Klotho prevented the changes resembling premature cellular senescence associated with TNFα, such as the decrease in telomere length and the increase in ß-galactosidase-positive cells. Likewise exogenous Klotho prevented the increases in reactive oxygen species (ROS) activity, mitochondrial potential and cell apoptosis induced by TNFα.

Carbamylated low-density lipoprotein induces oxidative stress and accelerated senescence in human endothelial progenitor cells.

Carbamylated low-density lipoprotein (cLDL) plays a role in atherosclerosis. In this study we evaluate the effect of uremia on LDL carbamylation and the effect of cLDL and oxidized LDL (oxLDL; 200 µg/ml) on number, function, and genomic stability of endothelial progenitor cells (EPCs) obtained from healthy volunteers. cLDL was generated after incubation of native LDL (nLDL) with uremic serum from patients with chronic kidney disease (CKD) stages 2-4. Oxidative stress was measured by flow cytometry and fluorescent microscopy, mitochondrial depolarization by flow cytometry, senescence by ß-galactosidase activity and telomere length, and DNA damage by phosphorylated histone H2AX (γH2AX). The percentage of cLDL by uremic serum was related to the severity of CKD. Compared with nLDL, cLDL induced an increase in oxidative stress (62±5 vs. 8±3%, P<0.001) and cells with mitochondrial depolarization (73±7 vs. 9±5%, P<0.001), and a decrease in EPC proliferation and angiogenesis. cLDL also induced accelerated senescence (73±16 vs. 12±9%, P<0.001), which was associated with a decrease in the expression of γH2AX (62±9 vs. 5±3%, P<0.001). The degree of injury induced by cLDL was comparable to that observed with oxLDL. This study supports the hypothesis that cLDL triggers genomic damage in EPCs, resulting in premature senescence. We can, therefore, hypothesize that EPCs injury by cLDL contributes to an increase in atherosclerotic disease in CKD.

Global effects of fluvastatin on the prothrombotic status of patients with antiphospholipid syndrome.

OBJECTIVE: Numerous mechanisms have been proposed to explain the thrombotic/proinflammatory tendency of antiphospholipid syndrome (APS) patients. Prothrombotic monocyte activation by antiphospholipid antibodies involves numerous proteins and intracellular pathways. The anti-inflammatory, anticoagulant and immunoregulatory effects of statins have been aimed as a therapeutic tool in APS patients. This study delineates the global effects of fluvastatin on the prothrombotic tendency of monocytes from APS patients. METHODS: Forty-two APS patients with thrombosis and 35 healthy donors were included in the study. APS patients received 20 mg/day fluvastatin for 1 month. Blood samples were obtained before the start, at the end and 2 months after the end of treatment. RESULTS: After 1 month of treatment, monocytes showed a significant inhibition of tissue factor, protein activator receptors 1 and 2, vascular endothelial growth factor and Flt1 expression that was related to the inhibition of p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa B/Rel DNA-binding activity. Proteomic analysis showed proteins involved in thrombotic development (annexin II, RhoA and protein disulphide isomerase) with altered expression after fluvastatin administration. In-vitro studies indicated that the inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase by fluvastatin might inhibit protein prenylation and MAPK activation. CONCLUSION: The data from this study support the belief that fluvastatin has multiple profound effects in monocyte activity, which might contribute to thrombosis prevention in APS patients.

Senescent CD14+CD16+ monocytes exhibit proinflammatory and proatherosclerotic activity.

In elderly subjects and in patients with chronic inflammatory diseases, there is an increased subset of monocytes with a CD14(+)CD16(+) phenotype, whose origin and functional relevance has not been well characterized. In this study, we determined whether prolonged survival of human CD14(++)CD16(-) monocytes promotes the emergence of senescent cells, and we analyzed their molecular phenotypic and functional characteristics. We used an in vitro model to prolong the life span of healthy monocytes. We determined cell senescence, intracellular cytokine expression, ability to interact with endothelial cells, and APC activity. CD14(+)CD16(+) monocytes were senescent cells with shortened telomeres (215 ± 37 relative telomere length) versus CD14(++)CD16(-) cells (339 ± 44 relative telomere length; p < 0.05) and increased expression of ß-galactosidase (86.4 ± 16.4% versus 10.3 ± 7.5%, respectively; p = 0.002). CD14(+)CD16(+) monocytes exhibited features of activated cells that included expression of CD209, release of cytokines in response to low-intensity stimulus, and increased capacity to sustain lymphocyte proliferation. Finally, compared with CD14(++)CD16(-) cells, CD14(+)CD16(+) monocytes showed elevated expression of chemokine receptors and increased adhesion to endothelial cells (19.6 ± 8.1% versus 5.3 ± 4.1%; p = 0.033). In summary, our data indicated that the senescent CD14(+)CD16(+) monocytes are activated cells, with increased inflammatory activity and ability to interact with endothelial cells. Therefore, accumulation of senescent monocytes may explain, in part, the development of chronic inflammation and atherosclerosis in elderly subjects and in patients with chronic inflammatory diseases.

Differential expression of protease-activated receptors in monocytes from patients with primary antiphospholipid syndrome.

OBJECTIVE: To investigate the expression of protease-activated receptors (PARs), their potential regulation by anticardiolipin antibodies (aCL), and their association with the expression of other molecules relevant to thrombosis in monocytes obtained from 62 patients with primary antiphospholipid syndrome (APS). METHODS: Monocytes were isolated from peripheral blood mononuclear cells by magnetic depletion of nonmonocytes. Expression of tissue factor (TF) and PARs 1-4 genes was measured by quantitative real-time reverse transcription-polymerase chain reaction. Cell surface TF and PARs 1-4 expression was analyzed by flow cytometry. For in vitro studies, purified normal monocytes were incubated with purified APS patient IgG, normal human serum IgG, or lipopolysaccharide, in the presence or absence of specific monoclonal antibodies anti-PAR-1 (ATAP2) or anti-PAR-2 (SAM11) to test the effect of blocking the active site of PAR-1 or PAR-2. RESULTS: Analysis of both mRNA and protein for the 4 PARs revealed significantly increased expression of PAR-2 as compared with the control groups. PAR-1 was significantly overexpressed in APS patients with thrombosis and in the control patients with thrombosis but without APS. PAR-3 expression was not significantly altered. PAR-4 expression was absent in all groups analyzed. In addition, we demonstrated a correlation between the levels of PAR-2 and the titers of IgG aCL, as well as parallel behavior of TF and PAR-2 expression. In vitro, IgG from APS patients significantly increased monocyte expression of PAR-1 and PAR-2. Inhibition studies suggested that there was direct cross-talk between TF and PAR-2, such that inhibition of PAR-2 prevented the aCL-induced expression of TF. CONCLUSION: These results provide the first demonstration of increased expression of PARs in monocytes from patients with APS. Thus, PAR antagonists might have therapeutic potential as antithrombotic agents in APS.

Effect of different dialysis modalities on microinflammatory status and endothelial damage.

BACKGROUND AND OBJECTIVES: We studied the relationship between microinflammation and endothelial damage in chronic kidney disease (CKD) patients on different dialysis modalities. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Four groups of CKD stage 5 patients were studied: 1) 14 nondialysis CKD patients (CKD-NonD); 2) 15 hemodialysis patients (HD); 3) 12 peritoneal dialysis patients with residual renal function >1 ml/min (PD-RRF >1); and 4) 13 peritoneal dialysis patients with residual renal function

Carbamylated darbepoetin derivative prevents endothelial progenitor cell damage with no effect on angiogenesis.

Erythropoietin (EPO) prevents cell apoptosis induced by oxidative stress. Carbamylated EPO maintains the tissue-protective activities of the unmodified EPO but does not stimulate erythropoiesis. This study evaluates whether carbamylated erythropoietin is as effective as recombinant human erythropoietin in protecting endothelial progenitor cells (EPCs) from apoptosis without stimulating erythropoiesis. Experiments were performed in an erythroid cell line (UT-7) and in human EPCs. Cell signals regulating proliferation and apoptosis (Jak-2, Akt, Erk1/2, NFkappaB and Stat-5) were measured by Western blotting. In human EPCs, cell senescence, apoptosis and proliferation were assessed by acidic beta-gal and measurement of telomere length, TUNEL and PCNA labeling, respectively. Angiogenesis was evaluated using the endothelial tube formation assay. In UT-7, carbamylated erythropoietin (C-darbe) induced phosphorylation of the anti-apoptotic Jak-2/Akt signal and, as opposed to recombinant human erythropoietin (darbe), did not produce a significant activation of cell proliferating signals. Darbe increased the percent of proliferating EPCs and promoted angiogenesis. By contrast, C-darbe failed to stimulate proliferation of EPCs. Both C-darbe and darbe equally reduced apoptosis and senescence. Thus, C-darbe protects EPCs from apoptosis and does not increase erythropoiesis.

Proteomic analysis in monocytes of antiphospholipid syndrome patients: deregulation of proteins related to the development of thrombosis.

OBJECTIVE: Antiphospholipid antibodies (aPL) are closely related to the development of thrombosis, but the exact mechanism(s) leading to thrombotic events remains unknown. In this study, using proteomic techniques, we evaluated changes in protein expression of monocytes from patients with antiphospholipid syndrome (APS) related to the pathophysiology of the syndrome. METHODS: Fifty-one APS patients were included. They were divided into 2 groups: patients with previous thrombosis, and patients with recurrent spontaneous abortion. As controls, we studied patients with thrombosis but without aPL, and age- and sex-matched healthy subjects. RESULTS: The proteins that were more significantly altered among monocytes from APS patients with thrombosis (annexin I, annexin II, protein disulfide isomerase, Nedd8, RhoA proteins, and Hsp60) were functionally related to the induction of a procoagulant state as well as to autoimmune-related responses. Proteins reported to be connected to recurrent spontaneous abortion (e.g., fibrinogen and hemoglobin) were also determined to be significantly deregulated in APS patients without thrombosis. In vitro treatment with IgG fractions purified from the plasma of APS patients with thrombosis changed the pattern of protein expression of normal monocytes in the same way that was observed in vivo for monocytes from APS patients with thrombosis. CONCLUSION: For the first time, proteomic analysis has identified novel proteins that may be involved in the pathogenic mechanisms of APS, thus providing potential new targets for pathogenesis-based therapies for the disease.

Microinflammation and endothelial damage in hemodialysis.

BACKGROUND: Chronic kidney disease (CKD) stage 4-5 patients have increased cardiovascular morbidity and mortality rates compared with the general population. Chronic inflammation has been proposed as a cardiovascular risk factor. We have previously demonstrated that the majority of CKD patients show a microinflammatory state with an increased percentage of CD14+/CD16+ monocytes in peripheral blood, even in patients who do not show clinical evidence of inflammatory disease. However, the role played by these microinflammatory cells on the endothelial damage that precede the development of cardiovascular disease has not been investigated. METHODS: To study the effect of microinflammation on endothelial cell injury we have developed an experimental co-culture model in which isolated CD14+/CD16+ cells were seeded in 24-well tissue-culture plates. Human umbilical vein endothelial cells were placed on the top of the culture well in a insert that permitted intercellular soluble network communication. To stimulate the release of proinflammatory products, monocytes were activated with substimulating doses of bacterial DNA. Endothelial injury was characterized measuring intracellular reactive oxygen species activity and cell apoptosis. RESULTS: Only CD14+/CD16+ cells released proinflammatory cytokines when they were stimulated by bacterial DNA. In the culture wells in which inflammatory cytokines were detected, endothelial cells showed an increased reactive oxygen species activity and features of apoptosis. CONCLUSIONS: Our results support the hypothesis that independently of uremia, in CKD stage 4-5 patients microinflammation mediated by CD14+/CD16+ cells induces endothelial damage and thus may contribute to the increased risk of atherosclerosis and cardiovascular disease that has been reported in this population.

Inhibition of Flt3-activating mutations does not prevent constitutive activation of ERK/Akt/STAT pathways in some AML cells: a possible cause for the limited effectiveness of monotherapy with small-molecule inhibitors.

The Flt3 receptor tyrosine kinase is a critical mediator in the pathogenesis of acute myeloid leukaemia (AML). Flt3-activating mutations have been associated with poor prognosis and decreased overall survival of AML patients, thus Flt3 constitutes an ideal target for drug treatment of such disease. Unfortunately, the monotherapy with small-molecule tyrosine kinase inhibitors in clinical trials shows that remission is not permanent, presumably by resistance of Flt3 mutants to inhibitors. An alternative approach for treatment is based on the cooperation between Flt3 and additional intracellular pathways for AML transformation in some patients. Thus, the inhibition of both Flt3 and such pathways may be exploited for successful treatment of the disease. We investigated the importance of Flt3-activating mutations for the constitutive activation of intracellular pathways in primary AML cells, and their effect on cell survival. We found that the main compounds involved in the differentiation, proliferation and survival of AML (MAPK/AKT/STAT) were constitutively activated. However, only four samples showed internal tandem duplications (ITDs) for Flt3. Surprisingly, contrary to previous reports, we found that inhibition of ITD/Flt3 activity did not prevent the phosphorylation of ERK, STAT5 or Akt in some primary AML cells. In parallel, we found that in these cells, Flt3 and ERK or Akt cooperate to regulate cell survival. Our results support the hypothesis that the optimal therapeutic treatment of AML may require not only the oncogenic tyrosine kinase, but also the appropriate combination of different specific inhibitors, thus providing a more effective approach to reverse leukaemogenesis. Thus, we propose that each AML patient should have an individually tailored combination treatment.

Proteomic analysis of acute myeloid leukemia: Identification of potential early biomarkers and therapeutic targets.

The main goal of this study was to analyze, using proteomic techniques, changes in protein expression of acute myeloid leukemia (AML) cells that could give insights into a better early prognosis for tumor pathophysiology. Proteomic analysis of different subtypes of AML cells was carried out using 2-DE and MALDI-TOF PMF analysis. Proteins identified as more significantly altered between the different AMLs belonged to the group of suppressor genes, metabolic enzymes, antioxidants, structural proteins and signal transduction mediators. Among them, seven identified proteins were found significantly altered in almost all the AML blast cells analyzed in relation to normal mononuclear blood cells: alpha-enolase, RhoGDI2, annexin A10, catalase, peroxiredoxin 2, tromomyosin 3, and lipocortin 1 (annexin 1). These differentially expressed proteins are known to play important roles in cellular functions such as glycolysis, tumor suppression, apoptosis, angiogenesis and metastasis, and they might contribute to the adverse evolution of the disease. Proteomic analysis has identified for the first time novel proteins that may either help to form a differential prognosis or be used as markers for disease outcome, thus providing potential new targets for rational pathogenesis-based therapies of AML.

Antiphospholipid-mediated thrombosis: interplay between anticardiolipin antibodies and vascular cells.

The antiphospholipid syndrome (APS) is characterized by thrombosis or pregnancy morbidity in the presence of antiphospholipid autoantibodies (aPL). aPL are a heterogeneous family of autoantibodies with diverse cross-reactivities whose origin and role have not been fully elucidated. Many of the autoantibodies associated with APS are directed against phospholipid-binding plasma proteins, such as beta2-GPI and prothrombin, or phospholipid-protein complexes. The mechanisms by which aPL cause thrombosis are not completely understood. There is no unique mechanism able to explain all symptoms associated with the presence of aPL. Different theories have been proposed, including the effect of aPL on endothelial cells, monocytes, and platelets. aPL are able to recognize, injure, or activate cultured vascular endothelial cells. Cultured endothelial cells incubated with aPL express increased levels of cell adhesion molecules and tissue factor (TF), an effect mediated by beta2-GPI, and may promote inflammation and thrombosis. Overexpression of TF has been also shown in monocytes in vitro and ex vivo. TF is the major initiator of coagulation in vivo; thus, its dysregulation may be one of the most important contributors to thrombosis. Effects of aPL upon platelets are not completely elucidated. aPL bind anionic phospholipid but they are normally in the inner side of cell membranes. When platelets are activated by different agonists, anionic phospholipids are exposed. There is some evidence showing that activated platelets are present in aPL-positive patients. Increased levels of beta-thrombomodulin, and microvesicle formation seem to support this hypothesis. Activated platelets may contribute to thrombosis by persistent exposure of a procoagulant surface.