Autism and immunity: revisited study

Autism spectrum disorder is of interest neurochemically because it represents a relatively homogeneous disorder with regard to disease development, abnormal cognitive development and intellectual development disturbance. A consistent finding in autistic children is a high number of mast cells and a high level of serotonin which is also found at elevated concentrations in the urine of autistic patients. In addition, a dysfunction of clinical conditions, such as gastrointestinal and immunological symptoms, is frequently noted in autistic children, however, IgE does not appear to be prevalent in these children but probably an increase of cytokines/chemokines produced by mast cells at an early age may play an important role. Therefore an immune hypothesis, involving also autoimmunity, is one possible pathogenetic mechanism in autism. In conclusion, mast cell activation could contribute to immune and neuroinflammatory abnormalities that are evident in patients with autism spectrum disorders.

Phosphodiesterase type-5 inhibitor and oxidative stress

Erectile dysfunction (ED) is a common medical condition that affects the sexual life of millions of men worldwide. Numerous physical and psychological factors are involved in normal erectile function, including neurological, vascular, hormonal and cavernous functions. The current therapy for the condition is pharmacological and psychotherapeutic which regulates the erectile function and amplifies the NO-mediated response. The aim of this work is to test the action of three common phosphodiesterase inhibitors: Tadalafil, Sildenafil Citrate and Vardenafil at 0.05 microM on human monocytes, analyzing the expression of iNOS protein and mRNA by Western blot and rt-PCR, and production of NO by conversion of L-(2,3,4,5)-[3H]Arginine to L-(3H) citrulline. We also tested the efficiency of the antioxidant network by spectrophotometer (SOD, CAT, GPx and Gr), under normal conditions and after stimulation with LPS. The results showed an increase in ROS levels, similar for all the molecules with regard to the antioxidant enzymes. In all cases the treatment determines a response to the limited efficiency, arriving at a situation in which phosphodiesterase inhibitors + LPS clearly show oxidative stress.

Neuropeptide substance P induces mRNA expression and secretion of CXCL8 chemokine, and HDC in human umbilical cord blood mast cells

PURPOSE

Mast cells play an important role in innate and acquired immunity and are thought to be the cellular origin of most proteases and cytokines. Substance P (SP) and its receptor, NK-1R, play critical roles in immune regulation in human and animal models of inflammation.

METHODS

We used mature human cord blood mast cells (HCBMC) differentiated from cord blood CD34+ precursor activated with SP in culture.

RESULTS

Our data indicate that Substance P strongly activates mature HCBMC in releasing CXCL8 expression and secretion (

CONTROL

1.200 +/- 1.0; SP: 4.10 +/- 0.90; P < 0.01). Moreover, in a RT-PCR, HCBMC expressed CXCL8 mRNA after Substance P activation. Since calcium ionophore A23187 is a pharmacological activator that raises cytosolic free calcium ion concentraion and stimulates mast cells in the production and secretion of proinflammatory compounds, it was used as positive control. In addition, we found that HCBMCs generate the transcription of histidine decarboxylase (HDC), the enzyme responsible for the generation of histamine from histidine, after SP treatment. Since CXCL8 is a member of the CXC chemokine subfamily with potent chemotactic activity and is a primary inflammatory cytokine we conclude that our results, obtained from HCBMC cultures, a good and valid model in vitro, support the concept that the neurogenic system modulates inflammatory events by Substance P-mediated HCBMC chemokine CXCL8 release.

CONCLUSION

The expression, synthesis and release of CXCL8 suggest an increase of inflammatory process in vivo mediated by the recruitment and infiltration of inflammatory cells in inflamed tissues.

Reduction of free radicals in multiple sclerosis: effect of glatiramer acetate (Copaxone)

Free radicals have been found in high concentrations within inflammatory multiple sclerosis (MS) lesions. The superoxide anion (O(2)(-)) reacts rapidly with nitric oxide (NO), producing peroxynitrite (ONOO(-)). Glatiramer acetate (GA) is a specific MS immunomodulator that induces the synthesis of Th2 cytokines, and reduces the frequency of relapses and the formation of active brain lesions. Proinflammatory cytokines could play a role in free radicals production in the peripheral immune system as well as in the central nervous system (CNS). The effect of GA on iNOS, superoxide radicals (O(2)(-)) and 3-nitrotyrosine production by peripheral blood adherent mononuclear cells (PBAMs) was assessed. Our findings demonstrate that in vitro GA reduced spontaneous and LPS-induced iNOS, 3-nitrotyrosine, NO and O(2)(-) production, and that similar inhibition can be demonstrated ex vivo in mononuclear cells obtained from GA-treated patients. The inhibition of the production of free radicals in PBAMs may represent a new therapeutic mechanism against inflammation during MS.

iNOS activity in the aged rat liver tissue

Free radical damage to many cellular components has been proposed as the main mechanism underlying the aging process. In the liver, NO can be generated by iNOS, but also by the constitutively expressed endothelial NOS (eNOS). iNOS enzyme appears to be expressed in liver disease such as cirrhosis and fulminant hepatitis, while the eNOS is expressed in physiological conditions. Ten young and ten old Wistar rats were sacrificed and their livers were excised. Liver sections were incubated with an anti-iNOS antibody of rabbit origin. RT-PCR and Western blot analysis were performed and nitric oxide activity was calculated. A significant increase of iNOS immunoreactivity was seen in the aged liver sections versus young liver sections. iNOS protein is expressed in greater quantities in the aged group, compared to the young group. In this study we show, for the first time, that aging in the rat liver is accompanied by a spontaneous induction of iNOS mRNA, high levels of iNOS protein and immunohistochemistry/image analysis.

Plasmatic markers of muscular stress in isokinetic exercise

In this paper we examined the variations of plasmatic concentrations of hypoxanthine and xanthine, and their relation with other important indicators of muscular stress creatine-kinase (CK), myoglobin, uric acid, leucocytes, in prolonged, isokynetic physical exercise, performed in a concentric mode at different joint excursion. Twenty healthy male subjects performed isokinetic exercises in concentric-concentric mode, with joint excursion of 30, 60, 90 deg/sec. Blood samples were drawn at rest, immediately after exercise and after 45 min of recovery. The plasmatic concentration of hypoxanthine increased at the end of physical exercise, compared to the rest value of about 1,5 micromol/L, up to a level of greater than 19 micromol/L; the values were higher after a period of recovery of 45 min and the increase varies considerably according to the type of exercise that was performed. Myoglobin has a slight but sensible increment too, with the same trend as hypoxanthine, while CK increase without correlation to the type of exercises. The relation with other indicators of muscular activity demonstrates that in none of the different isokinetic exercises, performed at concentric mode, was there ultrastructural damage, while it is possible to come across a considerable metabolic stress, which is dissimilar in the different kinds of exercises. The results suggest that hypoxanthine can be useful in monitoring the effectiveness of a work load and the metabolic stress consequences on the muscle tissue in training or rehabilitation programs. The results also suggest that even myoglobin, at small concentrations, can have the same function.

Modulation of MCP-1 and iNOS by 50-Hz sinusoidal electromagnetic field

The purpose of this study was to investigate whether overnight exposure to 1 mT-50 Hz extremely low-frequency sinusoidal electromagnetic field (EMF) affects the expression and production of inducible nitric oxide synthase (iNOS) and monocyte chemotactic protein-1 (MCP-1) in human monocytes. RT-PCR and Western blot analysis demonstrate that EMF exposure affects the expression of iNOS and MCP-1 in cultured human mononuclear cells at the mRNA level and protein synthesis. Interestingly, the effects of EMF exposure clearly differed with respect to the potentiation and inhibition of iNOS and MCP-1 expression. Whereas iNOS was down-regulated both at the mRNA level and at the protein level, MCP-1 was up-regulated. These results provide helpful information regarding the EMF-mediated modulation of the inflammatory response in vivo. However, additional studies are necessary to demonstrate that EMF acts as a nonpharmacological inhibitor of NO and inducer of MCP-1 in some diseases where the balance of MCP-1 and NO may be important.

Adherence of uremic erythrocytes to vascular endothelium decreases endothelial nitric oxide synthase expression

BACKGROUND

High prevalence of atherosclerotic cardiovascular events accounts for much of the mortality among patients suffering from end-stage renal disease (ESRD). Endothelial dysfunction as a pathogenic mechanism might contribute to increasing the cardiovascular risk of ESRD. Reduced endothelium-dependent vasodilation has consistently been observed in chronic renal failure patients. Since nitric oxide (NO) is the principal endothelium-derived vasodilator, a reduction in the NO bioavailability may be envisaged in ESRD patients.

METHODS

To clarify whether exposure to erythrocytes from ESRD patients might modulate NO release by the endothelium, we evaluated endothelial NO synthase (eNOS) protein levels (Western blot), eNOS mRNA quantity (real-time PCR), and NOS activity (conversion of L-[3H] arginine in L-[3H] citruline) in endothelial cultures stimulated by erythrocytes from healthy subjects and ESRD patients.

RESULTS

A time-dependent decrease in eNOS protein levels was evident in cultures treated with erythrocytes from ESRD patients. This observation was consistent with the decreased eNOS mRNA quantities induced by erythrocytes from such patients. Moreover, compared to controls, NOS activity exhibited a significant reduction after incubation with erythrocytes from ESRD patients. The observed eNOS reduction induced by erytrocytes from ESRD patients was totally abolished by annexin V, able to mask red blood cell (RBC) surface-exposed phosphatidylserine.

CONCLUSION

These findings suggest that adhesion of erythrocytes from ESRD patients to vascular endothelium may cause a decrease in the levels of eNOS mRNA and protein, and inhibition of NOS activity. This might contribute to endothelial dysfunction, and may play a role in the pathogenesis of cardiovascular disease in ESRD patients.

Simvastatin Attenuates Expression of Cytokine-inducible Nitric-oxide Synthase in Embryonic Cardiac Myoblasts

Cardiac stem cells or myoblasts are vulnerable to inflammatory stimulation in hearts with infarction or ischemic injury. Widely used for the prevention and treatment of atherosclerotic heart disease, the cholesterol-lowering drugs statins may exert anti-inflammatory effects. In this study, we examined the impact of inhibition of hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase with simvastatin on the expression of inducible nitric-oxide synthase (iNOS) in embryonic cardiac myoblasts stimulated with the proinflammatory cytokines, interleukin-1 or tumor necrosis factor. Treatment with simvastatin significantly reduced the levels of iNOS mRNA and protein in cytokine-treated rat H9c2 cardiac embryonic myoblasts. Addition of the HMG-CoA reductase product, L-mevalonate, and the by-product of cholesterol synthesis, geranylgeranyl pyrophosphate, could reverse the statin inhibitory effect on iNOS expression. Simvastatin treatment lowered the Rho GTPase activities, whereas the Rho-associated kinase inhibitor Y27632 partially blocked the statin inhibitory effect on nitrite production in the cytokine-treated H9c2 cells. Treatment with simvastatin led to inactivation of NF-kappaB by elevation of the NF-kappaB inhibitor IkappaB and reduction of the NF-kappaB nuclear contents in the cytokine-stimulated H9c2 cells. Hence, treatment with simvastatin can attenuate iNOS expression and NO synthesis in cytokine-stimulated embryonic cardiac myoblasts. The statin inhibitory effect may occur through isoprenoid-mediated intracellular signal transduction, which involves several key signal proteins, such as Rho kinase and IkappaB/NF-kappaB. These data suggest that statin therapy may protect the cardiac myocyte progenitors against the cytotoxicity of cytokine-induced high output of NO production in infarcted or ischemic hearts with inflammation.

Chronic treatment with rosuvastatin modulates nitric oxide synthase expression and reduces ischemia-reperfusion injury in rat hearts

OBJECTIVE

Due to reported modulatory effects of statins on nitric oxide synthase (NOS) expression, we tested the hypothesis of protective effects of in vivo chronic treatment with rosuvastatin, a novel 3-hydroxy-3-methyl-glutaryl coenzyme A-reductase inhibitor, on ischemia-reperfusion injury, and investigated mechanisms involved.

METHODS

After 3 weeks of in vivo treatment with rosuvastatin (0.2-20 mg/kg/day) or placebo, excised hearts from Wistar rats were subjected to 15 min global ischemia and 22-180 min reperfusion. We evaluated creatine-phosphokinase and nitrite levels in the coronary effluent, heart weight changes, microvascular permeability (extravasation of fluoresceine-labeled albumin), ultrastructural alterations, and the expression of endothelial (e) and inducible (i) nitric oxide synthase (NOS) (by reverse-transcription polymerase chain reaction and Western blotting).

RESULTS

Rosuvastatin 0.2 and 2 mg/kg/day significantly reduced myocardial damage and vascular hyperpermeability, concomitant with a reduction in endothelial and cardiomyocyte lesions. At 2 mg/kg/day, rosuvastatin significantly increased eNOS mRNA and protein compared with untreated hearts, and conversely decreased iNOS mRNA and protein, as well as nitrite production after ischemia-reperfusion. The addition of the NOS inhibitor N(omega)-nitro-L-arginine methylester (L-NAME, 30 micromol/L) significantly reduced cardioprotection against ischemia-reperfusion.

CONCLUSIONS

Chronic treatment with rosuvastatin before ischemia reduces ischemia-reperfusion injury and prevents coronary endothelial cell and cardiomyocyte damage by NO-dependent mechanisms.

Gingival endothelial and inducible nitric oxide synthase levels during orthodontic treatment: a cross-sectional study

This study uses a cross-sectional design to examine the endothelial and inducible nitric oxide synthase (eNOS and iNOS, respectively) levels of gingival tissue. Fifteen subjects, 10 female and 5 male individuals (aged 14.6-21.2 years; mean 17.4 +/- 1.8 years), who needed extraction of the four first premolars for orthodontic reasons and who had indications for a gingivectomy were enrolled in the study. In each patient, two maxillary/mandibular premolars were extracted, and two months later an orthodontic appliance was placed in the same arch. A canine undergoing treatment for distal movement served as the test tooth (TT), whereas its contralateral canine was used as the control tooth (CT). The CT was included in the orthodontic appliance but was not subjected to the orthodontic force. Two weeks after the orthodontic appliance placement, clinical data consisting of the presence of supragingival plaque, bleeding on probing, and probing depth were collected from each experimental tooth. Immediately after, gingival tissue was collected from the distal aspect of each TT and CT for immunohistochemistry, messenger RNA reverse transcription by polymerase chain reaction, and Western blot analysis for both eNOS and iNOS. The results showed that no differences in clinical conditions occurred between the experimental teeth. On the contrary, both the eNOS and iNOS levels and the expression of the TTs were significantly greater than those of the CTs (all comparisons significant to P < .01). Our results indicate a role for gingival eNOS and iNOS during the early phases of orthodontic treatment in humans.

Nitric oxide synthase in healthy and inflamed human dental pulp

Nitric oxide synthase (NOS) plays a significant role in the pathogenesis of pulpitis. In this study, we hypothesized the existence of endothelial (eNOS) and inducible (iNOS) enzyme isoforms in human dental pulp. Extracted third molar pulps were divided into groups based on clinical diagnosis: healthy, hyperemic, and irreversible pulpitis. We have localized the eNOS and iNOS by immunohistochemistry and have tested their mRNA expression by RT-PCR and protein levels by Western blots. eNOS is present in the endothelial cells and odontoblasts of the healthy pulp, but an elevation of eNOS mRNA and protein levels with a concomitant dilation of vessels was characteristic under pathological conditions. Healthy pulp tissue failed to exhibit any iNOS; however, acute inflammation enhanced the mRNA and protein levels of iNOS, mainly in the leukocytes. There are differences in localization and expression between eNOS and iNOS in healthy and inflamed dental pulp.

Inducible nitric oxide synthase and heme oxygenase-1 in rat heart: direct effect of chronic exposure to hypoxia

Hypoxia is a potent regulator of various biological process. Mammalian cells respond to hypoxia by increased expression of several genes. The aim of this study was to evaluate the effects of chronic exposure to low oxygen tension on the induction of inducible nitric oxide synthase (iNOS) and heme oxygenase-1 (HO-1) in rat heart. Male Wistar rats were assigned randomly to 4 groups: (A) control rats maintained in normoxic conditions for 7 and 14 days; (B) rats maintained in hypoxic conditions for 7 and 14 days; (C) rats maintained in normoxic conditions for 7 days and then transferred to hypoxic conditions for 7 days; and (D) rats maintained in hypoxic conditions for 7 days and then transferred to normoxic conditions for 7 days. In Group A, iNOS and HO-1 immunoreactivities were not evident; in Group B these immunoreactivities increased from day 7 to 14; in Group C the immunoreactivities decreased on day 7, compared to day 14; and in Group D, the immunoreactivities increased on day 7, compared to day 14. These findings were confirmed by Western blot analyses of the respective proteins and by rt-PCR assays of the corresponding mRNAs. The results indicate that the adaptive response to hypoxia involves up-regulation of HO-1 through iNOS activation in cardiac cells. HO-1 helps to regulate vascular tone via CO and thereby participates in an important cardiac defense mechanism.

Left ventricular wall stress as a direct correlate of cardiomyocyte apoptosis in patients with severe dilated cardiomyopathy

BACKGROUND

Apoptosis has been implicated as a possible mechanism in the development of heart failure (HF), but the mechanisms involved remain unclear. In patients with severe dilated cardiomyopathy, we evaluated cardiomyocyte apoptosis in relation to the transmural distribution of Bax and Bcl-2 proteins (2 molecules inhibiting or promoting apoptosis, respectively) and left ventricular wall stresses.

METHODS

We studied the presence and distribution of cardiomyocyte apoptosis in 90 tissue samples obtained from 8 patients who were undergoing left ventricular reduction with the Batista (ventricular remodeling) operation. Apoptosis was assessed in tissue samples taken from the entire left ventricular thickness (subdivided in subepicardial, midmyocardial, and subendocardial sections) with the terminal deoxynucleotidyl transferase mediated dUTP-biotin nick-end labeling (TUNEL) technique and DNA agarose gel electrophoresis. The expression of Bcl-2 and Bax proteins were determined with both Western analysis and immunohistochemistry.

RESULTS

TUNEL-positive cells (apoptotic index) were 2.3% +/- 1.4%. Apoptotic cells were predominantly distributed in the subendocardium, where higher levels of Bax protein were detected. The ratio of Bax to Bcl-2 proteins (Bax/Bcl-2) was similar in the midmyocardium or subepicardium, but increased in the subendocardium, where it was directly related to systolic wall stress (y = 0.009x - 0.629; r2 = 0.85, P <.001). The apoptotic index was also directly related to systolic and end-diastolic stresses calculated from hemodynamic and echocardiographic data (r2 = 0.77, P <.001 and r2 = 0.40, P <.01, respectively).

CONCLUSIONS

In patients with dilated cardiomyopathy, in whom cardiomyocyte apoptosis is an important cause of cell loss, apoptosis is more extensively localized in the subendocardium and strictly related to ventricular wall stresses and the Bax/Bcl-2 ratio.

Effect of chronic hypoxia on inducible nitric oxide synthase expression in rat myocardial tissue

The purpose of our study was to evaluate the effect of chronic exposure to low cellular oxygen tension (90% N2 and 10% O2 for 14 days) in inducing apoptosis and activation of transcription and translation of inducible nitric oxide (NO) synthase (iNOS) in rat hearts tissue. Rats were divided into four groups: normoxic, hypoxic, rats maintained in normoxic condition for 7 days and subjected to hypoxic conditions for another 7 days, and rats maintained in hypoxic condition for 7 days and subjected to normoxic conditions for another 7 days. At the 7th and 14th days, five rats from each group were sacrificed. Immunohistochemical and Western blot analysis were performed on myocardial tissue to reveal the presence of iNOS. Expression of iNOS was determined by RT-PCR. Apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling and by detection of internucleosomal DNA fragmentation by electrophoresis. Electrophoretic analysis of DNA showed oligonucleosomal fragmentation in the hypoxic groups, but no ladder was observed in the other groups. This data was confirmed through end labeling with streptavidin-biotin (biotin d-UTP). iNOS expression was evaluated through immunohistochemical techniques (Ab anti-iNOS) and Western blotting, and the results were quantified with a computerized imaging analysis. The expression of iNOS protein was greater in the hypoxic groups; in the normoxic groups, only a nonspecific background was detected. This data was supported with results obtained through RT-PCR, which showed the specific transcription of mRNA for iNOS in the same experimental conditions. In addition, the iNOS activity was also evaluated and was found to be more active in the hypoxic groups (0.1 +/- 0.01 vs 0.02 +/- 0.003). The present study shows that exposure to low oxygen tension is capable of inducing programmed cell death and activating iNOS.

Heme Oxigenase-1 (HO-1) and Oxidative Stress in Rat Heart

Low oxygen tension (hypoxia) is a potent regulator of diverse biological processes. Mammalian cells respond to hypoxia in part by increased expression of several genes that encode for tissue-specific and ubiquitous proteins. The aim of this study was to evaluate the effects of chronic exposure to low tension of oxygen (hypoxia) on the induction of heme-oxygenase-1 (HO-1) as an oxidative stress model.

Adult male Wistar rats were used and subdivided randomly in two groups: A:(n=10) maintained in normoxic conditions and B: (n=10) maintained in hypoxic conditions. The animal of both groups were sacrificed after 14 days. Group A showed an evident non-specific reaction. Group B presented an increased positively of HO-1 immunoreaction. This data was confirmed by western blot analysis of protein and by the study of mRNA through rtPCR. These results suggest that myocardial adaptive response to hypoxia involves up-regulation of HO-1 in cardiac cells, indicating that this enzyme may participate in regulating vascular tone via CO and thereby contributing to the pathophysiologically important defense mechanism of the heart.

Phenotype modulation in cultures of vascular smooth muscle cells from diabetic rats: association with increased nitric oxide synthase expression and superoxide anion generation

Proliferative modification of vascular smooth muscle cell (vSMC) and impaired bioavailability of nitric oxide (NO) have both been proposed among the mechanisms linking diabetes and atherosclerosis. However, diabetes induced modifications in phenotype and nitric oxide synthase(s) (NOS) expression and activity in vSMC have not been fully characterized. In this study, cell morphology, proliferative response to serum, alpha-SMactin levels, eNOS expression and activity, cGMP intracellular content, and superoxide anion release were measured in cultures of vSMC obtained from aorta medial layer of ten diabetic (90% pancreatectomy, DR) and ten control (sham surgery, CR) rats. Vascular SMC from DR showed a less evident "hill and valley" culture morphology, increased growth response to serum, greater saturation density, and lower levels of alpha-SMactin. In the same cells, as compared to CR cells, eNOS mRNA levels and NOS activity were increased, while intracellular cGMP level was lower and superoxide anion production was significantly greater. These data indicate that chronic hyperglycemia might induce, in the vascular wall, an increased number of vSMC proliferative clones which persist in culture and are associated with increased eNOS expression and activity. However, upregulation of eNOS and increased NO synthesis occur in the presence of a marked concomitant increase of O(2-) production. Since NO bioavailability, as reflected by cGMP levels, was not increased in DR cells, it is tempting to hypothesize that the proliferative phenotype observed in DR cells is associated with a redox imbalance responsible quenching and/or trapping of NO, with the consequent loss of its biological activity.

Oxygen supply modulates MCP-1 release in monocytes from young and aged rats: decrease of MCP-1 transcription and translation is age-related

Hyper or hypoxia may affect the immune system's chemokine production. Monocyte chemotactic protein-1 (MCP-1), an important chemotactic cytokine can be activated by active oxygen species. Groups of rats were exposed to hypoxic and hyperoxic environmental conditions for 60 h and MCP-1 was determined in their peripheral blood mononuclear cells by Elisa and Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). In this study we evaluated if the ability of monocytes to produce MCP-1 under basal conditions or after stimulation with lipopolysaccharide (LPS) or phytohaemagglutinin (PHA) was differently affected by exposure to hyper or hypoxic conditions in young and aged rats. MCP-1 expression and production in monocyte/macrophages from rats at normoxic conditions was reduced in aged subjects. However, spontaneous, LPS or PHA-induced MCP-1 production was up-regulated by exposure to hyperoxic conditions in both young (62 +/- 8, 99 +/- 7, 102 +/- 8 pg/ml, respectively) and aged rats (79 +/- 4, 112 +/- 9, 117 +/- 10 pg/ ml, respectively). We conclude that hyperoxia is an important regulator of MCP-1 release and support the hypothesis that increased % of O2 may serve to initiate MCP-1 production which then serves to recruit and regulate the distribution of mononuclear cells to the sites of inflammation.

IL-10, an inflammatory/inhibitory cytokine, but not always

IL-10 has been previously called cytokine synthesis inhibiting factor, produced mostly by Th2 cells, macrophages and CD8+ cell clones. IL-10 is capable of inhibiting the synthesis of several cytokines from different cells, antigen or mitogen activated. IL-10 exerts its inhibition at the mRNA transcriptional and translational level. In addition, IL-10 is a co-stimulatory cytokine on activated T cells. For example, IL-10 inhibits NK cell activity, the production of Th1 cytokines, cytokines generated by peripheral blood mononuclear cells, and macrophage activity. On the other hand, IL-10 exerts immunostimulatory effects on B cells, cytotoxic T cell development and thymocytes. In mast cells derived from CD4+/CD133+ cells, IL-10 inhibits IL-6 and TNFalpha, and prostaglandin E(1) and E(2) induced by IL-6. Here, we report for the first time that IL-10 fails to inhibit tryptase and IL-6 from human mast cell-1 (HMC-1) and human umbilical cord blood-derived mast cells.

Enhanced adherence of human uremic erythrocytes to vascular endothelium: role of phosphatidylserine exposure

BACKGROUND

The exposure of phosphatidylserine (PS) on the outer leaflet of erythrocyte membrane may have several pathophysiological consequences including increased erythrocyte adherence to endothelial cells, a finding that seems relevant in pathologies with reported vascular injury.

METHODS

Because PS externalization increases in erythrocytes from patients suffering from chronic uremia, which is frequently associated with vascular damage, the adherence of uremic erythrocytes to human umbilical vein endothelial cell (HUVEC) monolayers and the role of PS exposure on such cell-cell interaction were studied.

RESULTS

The number of uremic erythrocytes adhering to HUVEC was markedly greater than with normal erythrocytes and significantly correlated (r = 0.88) with the percentage of PS-exposing erythrocytes in the population. Adhesion to the monolayers was significantly decreased when uremic erythrocytes were preincubated with either annexin V or PS-containing liposomes, and was strongly greater for PS-positive than PS-negative fluorescence-activated cell sorter (FACS)-sorted uremic erythrocytes. Binding occurred preferentially in the gaps of HUVEC monolayers and was enhanced by matrix exposure. Uremic erythrocytes adhered to immobilized thrombospondin, and binding to endothelial cells was significantly reduced when monolayers were incubated with antibodies to thrombospondin.

CONCLUSIONS

These findings suggest that PS externalization may promote increased uremic erythrocyte adhesion to endothelium, possibly via a direct interaction with matrix thrombospondin.

Interleukin-6 and mast cells

Interleukin (IL) 6 is a pleiotropic cytokine (26 kDa) that originally was named interferon beta 2 or B cell-stimulating factor or differentiating B cell factor inducing immunoglobulin production. IL-6 is produced in many diseases. After secretion, IL-6 binds to its receptor IL-6R alpha (gp 80), the IL-6R alpha complex then recruits the signal-transducing beta-subunit (gp 130), which is the functional complex for signal transduction. In addition, activation of Th2 cells or mast cells also produce IL-6, which mediates immune responses, inflammation, acute phase responses, hematopoiesis, cancer, inflammatory bowel disease, etc. IL-6 also is a crucial cytokine for mast cell maturation. Human cord blood CD34+ cells differentiate and grow into mast cells in the presence of stem cell factor (SCF) and IL-6, causing increases in cell size, frequency of chymase positive cells, and intracellular histamine levels when compared with cells treated with SCF alone. Activated mast cells increase IL-6 mRNA associated with protein kinase C (PKC) activity. IL-6 also up-regulates histamine production rather than increases its storage and is an important inducing factor for the expression of immunoglobulin E (IgE) Fc epsilon RI.

Verapamil reduces coronary endothelium damage and cardiomyocyte necrosis but not apoptosis after ischemia and reperfusion: ex-vivo study in rat hearts

We tested the hypothesis of beneficial effects of the calcium-blocker verapamil in a model of ischemia-reperfusion, and investigated its effects against coronary microcirculation and cardiomyocyte apoptosis. Isolated working rat hearts were subjected to 15 min global ischemia and 22-180 min reperfusion in the presence or absence of verapamil (0.25 &mgr;M). We evaluated creatinephosphokinase (CK) in coronary effluent, heart weight changes, microvascular permeability (extravasation of fluoresceine-labeled albumin), ultrastructural alterations, and cardiomyocyte apoptosis (by 1.5% agarose gel electrophoresis and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling technique). In this model, 0.25 &mgr;M verapamil significantly reduced myocardial damage, CK release and vascular hyperpermeability, concomitant with a reduction in endothelial and cardiomyocyte lesions; on the contrary, 0.25 &mgr;M verapamil was unable to reduce cardiomyocyte apoptosis. In conclusion, in the absence of perfusing granulocytes, the acute administration of a pharmacologically relevant verapamil concentration reduces ischemia-reperfusion injury and prevents coronary endothelial cell and cardiomyocyte necrotic cell death but it is unable to reduce apoptotic cell death in isolated working rat hearts.

Inhibition of MCP-1 and MIP-2 transcription and translation by mimosine in muscle tissue infected with the parasite Trichinella spiralis

Mimosine is a non-toxic plant aminoacid which is an effective inhibitor of DNA replication by acting at the S-phase. In this study we infected mice with T. spiralis, a nematode parasite, and studied the inflammatory response through the determination of MIP-2, a C-X-C chemokine and MCP-1, a C-C chemokine in the inflamed area around the parasitic cyst. The animals were infected and their diaphragms were tested for inflammatory response. MCP-1 and MIP-2 was tested after 1, 10, 20, 30, and 40 days post inoculation, before and after mimosine treatment. The inflammatory index was calculated by counting the white blood cells around the nematode cysts, while expression of MIP-2 and MCP-1 was calculated by ELISA method and transcription by Northern blot and RT-PCR. Here we found that mimosine strongly inhibited the inflammatory index in the diaphragmatic tissue at 10, 20, 30 and 40 days post-treatment. In these experiments, mimosine had no effect on the number of cysts produced. In addition, we found that MCP-1 transcription and translation was completely inhibited by mimosine, while MIP-2 transcription and translation was partially inhibited at 30 and 40 days; yet it was totally inhibited after 10 and 20 days in encysted diaphragm tissue infected by T. spiralis. Our studies suggest that mimosine has an inhibitory effect through the inhibition of cytoplasmatic serine hydroxymethyltransferase altering the cell cycle of white blood cells. This study suggests for the first time the premise that mimosine acts as an anti-inflammatory compound.