Peripheral Endothelial Cells Research Articles

Activated peripheral blood and endothelial cells in thalassemia patients.

Thalassemia patients have alterations in the expression of some activation and adhesion molecules on peripheral blood lymphocytes. We studied cell surface antigens on peripheral blood cells associated with the activation of these cells and soluble molecules produced by activated endothelium. We investigated the expression of CD11b, CD18, CD35, CD43, CD44, and CD69 on the peripheral blood monocytes, Cd11b, CD18, CD35, CD43, CD44, CD67 on peripheral blood neutrophils and CD38 and CD69 on peripheral blood lymphocytes. We studied 68 transfusion-dependent thalassemics (group A), 10 transfusion non-dependent thalassemics (group B), 18 beta-thalassemia carriers (group C), and 28 normal individuals. Relative fluorescence intensity was used to determine the antigen density. Analysis was performed with an EPICS ELITE flow cytometer. Furthermore, soluble intercelullar adhesion molecule 1 (sICAM-1), soluble vascular adhesion molecule 1 (sVCAM-1), and E-selectin, tumor necrosis factor (TNF) alpha, and interleukin (IL) 1beta were measured in the plasma of patients by enzyme-linked immunometric assay. The expression of CD11b, CD18, and CD69 on the monocytes of group A was significantly greater than in groups B and C and in controls, while CD44 was significantly downregulated in group A. CD11b, CD18, CD35, CD44, and CD67 on the surface of neutrophils and CD38 and CD69 on the surface of lymphocytes were also overexpressed in group A. CD44 was downregulated on the monocytes and upregulated on the neutrophils of the patients compared to controls. The levels of sICAM-1, sVCAM-1, E-selectin, TNF-alpha, and IL-1beta in the serum of patients in groups A and B were higher than those in group C and the controls. Endothelial activation markers are significantly increased in thalassemia patients, and activated blood cells circulate in the peripheral blood. These may be related to the vascular complications in these patients and might be useful markers for the follow-up of the vascular disease.

Detection and characterization of porcine endogenous retrovirus in porcine plasma and porcine factor VIII.

The pig genome contains porcine endogenous retroviruses (PERVs) capable of infecting human cells. Detection of infectious retrovirus in porcine peripheral blood mononuclear cells and endothelial cells suggested to us that pig plasma is likely to contain PERV. Both PERV env sequences and viral reverse transcriptase (RT) activity were detected in all plasma samples isolated from four NIH minipigs. To detect infectious virus from plasma, we performed a culture assay using three cell lines of feline, swine, and human origin that had previously been shown to be permissive for PERV. Infectious virus was successfully cultured from all four NIH minipig plasmas on the swine cell line ST-IOWA. Using RT-PCR with env-specific primers, we could detect expression of PERV class C envelope in the supernatant of ST-IOWA cells that had been exposed to each pig plasma. We next examined a pig plasma derivative, Hyate:C (porcine factor VIII), and found evidence of PERV particles, since all six lots examined were positive for PERV RNA and RT activity. However, infectious virus could not be detected in clinical lots of Hyate:C, suggesting that the manufacturing process might reduce the load of infectious virus to levels below detectable limits of the assay. Detection of infectious virus in porcine plasma confirms and extends the previous findings that certain porcine cells express PERV when manipulated in vitro and clearly demonstrates that there are porcine cells that express infectious PERV constitutively in vivo.

Elevation of serum soluble E-selectin and antisulfoglucuronyl paragloboside antibodies in amyotrophic lateral sclerosis

Immunological abnormality is often found in amyotrophic lateral sclerosis (ALS). Antibodies to sulfoglucuronyl paragloboside (SGPG) were reported in ALS, although the pathogenetic significance of the antibodies is still unknown. We have already demonstrated that SGPG, a unique glycolipid, is present in both peripheral nerve and vascular endothelial cells. To investigate whether serum anti-SGPG antibodies would participate in activation and/or injury of endothelial cells in ALS, we examined serum anti-SGPG antibodies in association with serum soluble E- and P-selectins, which are markers of activated endothelial cells, in 25 patients with ALS and 14 age-matched patients with other neurological diseases (ONDs) using the microtiter-ELISA method. Seven out of 25 ALS patients had anti-SGPG antibodies. Levels of sE-selectin were significantly higher in patients with ALS (48.5 ± 23.4 ng/ml) compared with ONDs (24.0 ± 11.8 ng/ml) (P < 0.005). Four out of seven ALS patients with anti-SGPG antibodies had concomitantly high sE-selectin levels. The mean sE-selectin levels were higher in patients with anti-SGPG antibodies (61.9 ± 25.2 ng/ml) than in those without anti-SGPG antibodies (43.3 ± 21.1 ng/ml). Anti-SGPG antibodies may take part in the activation and/or injury of endothelial cells. The increased expression of E-selectin may be related to an immunological process in some ALS patients.

Elevation of serum soluble E-selectin and antisulfoglucuronyl paragloboside antibodies in amyotrophic lateral sclerosis.

Immunological abnormality is often found in amyotrophic lateral sclerosis (ALS). Antibodies to sulfoglucuronyl paragloboside (SGPG) were reported in ALS, although the pathogenetic significance of the antibodies is still unknown. We have already demonstrated that SGPG, a unique glycolipid, is present in both peripheral nerve and vascular endothelial cells. To investigate whether serum anti-SGPG antibodies would participate in activation and/or injury of endothelial cells in ALS, we examined serum anti-SGPG antibodies in association with serum soluble E- and P-selectins, which are markers of activated endothelial cells, in 25 patients with ALS and 14 age-matched patients with other neurological diseases (ONDs) using the microtiter-ELISA method. Seven out of 25 ALS patients had anti-SGPG antibodies. Levels of sE-selectin were significantly higher in patients with ALS (48.5 +/- 23.4 ng/ml) compared with ONDs (24.0 +/- 11.8 ng/ml) (P < 0.005). Four out of seven ALS patients with anti-SGPG antibodies had concomitantly high sE-selectin levels. The mean sE-selectin levels were higher in patients with anti-SGPG antibodies (61.9 +/- 25.2 ng/ml) than in those without anti-SGPG antibodies (43.3 +/- 21.1 ng/ml). Anti-SGPG antibodies may take part in the activation and/or injury of endothelial cells. The increased expression of E-selectin may be related to an immunological process in some ALS patients.

Distribution of leukotriene B4 receptors in human hematopoietic cells

Leukotriene B4 (LTB4), a product of arachidonic acid metabolism, plays an important role in inflammatory responses. We have cloned from human erythroleukemia cells, a G protein-coupled receptor, designated P2Y7, which was later identified as the receptor for LTB4 (B-LTR). We have investigated the distribution of LTB4 receptors in various hematopoietic cells. Northern blotting and reverse transcription-coupled polymerase chain reaction (RT-PCR) analyses using radiolabeled LTB4 receptor cDNA as a probe indicated the presence of LTB4 receptor mRNA in peripheral blood leukocytes but not in platelets. Flow cytometry analysis of peripheral blood cells using specific LTB4 receptor antibodies revealed that monocytes, granulocytes, and lymphocytes, but not platelets, express LTB4 receptors. RT-PCR-Southern hybridization analysis revealed that peripheral blood leukocytes and human umbilical vein endothelial cells express the LTB4 receptor. Of the hematopoietic cell lines tested, promonocytic U937 cells, promyelocytic HL-60 cells, K562 cells, and human erythroleukemia cells express the LTB4 receptor. These results suggest a physiological role for the LTB4 receptor in the stimulation of monocytes, neutrophils, and endothelial cells.

VRAP Is an Adaptor Protein That Binds KDR, a Receptor for Vascular Endothelial Cell Growth Factor

A protein that binds the intracellular domain of KDR (KDR-IC), a receptor for vascular endothelial cell growth factor (VEGF), was identified by two-hybrid screening. Two-hybrid mapping showed that the VEGF receptor-associated protein (VRAP) interacted with tyrosine 951 in the kinase insert domain of KDR. Northern blot analysis identified multiple VRAP transcripts in peripheral leukocytes, spleen, thymus, heart, lung, and human umbilical vein endothelial cells (HUVEC). The predominant VRAP mRNA encodes a 389-amino acid protein that contains an SH2 domain and a C-terminal proline-rich motif. In HUVEC, VEGF promotes association of VRAP with KDR. Phospholipase C gamma and phosphatidylinositol 3-kinase, effector proteins that are downstream of KDR and important to VEGF-induced endothelial cell survival and proliferative responses, associate constitutively with VRAP. These observations identify VRAP as an adaptor that recruits cytoplasmic signaling proteins to KDR, which plays an important role in normal and pathological angiogenesis.

Molecular properties of central and peripheral histamine H1 and H2 receptors.

We identified and characterised histamine H1 and H2 receptor subtypes on rat cortical astrocytes in primary culture with radioligand binding studies and compared their molecular properties with peripheral (bovine vascular smooth muscle and endothelial cells) histamine H1 and H2 receptors. Our results showed the existence of a homogenous population of high affinity binding sites for 3H-mepyramine (Bmax = 281 fmol/mg protein, KD= 3.5 +/- 0.7 nM) and 3H-tiotidine (Bmax = 59 fmol/mg protein, KD = 1.9 +/- 0.7 nM) on astrocytes, which was further confirmed by competition binding studies using various H1 and H2 specific agonists/antagonists. We showed differences in the density of receptors and differences in the affinities of competing drugs for the same histamine receptor subtype (H1 and H2) between the tissues used, which indicate different molecular properties of the central and peripheral histamine receptors.

Dermal Fibroblasts Represent a Potent Major Source of Human Eotaxin: In Vitro Production and Cytokine-mediated Regulation

Accumulating evidence indicates that eotaxin plays an integral role in tissue recruitment of eosinophils in humans as well as in animals. To clarify which types of cells are actually important as sources of human eotaxin, we used a specific enzyme-linked immunosorbent assay (ELISA) to compare various types of hemopoietic and nonhemopoietic cells for the ability to produce eotaxin protein. Regardless of various conditioning, we failed to determine any significant eotaxin generation by peripheral leukocytes and vein endothelial cells (less than 20pg/ml). A small amount of immunoreactive eotaxin was detected in cultures of A549 bronchial epithelial cell line cells. In contrast, dermal fibroblasts were capable of generating extremely high, and potentially biologically relevant, amounts of eotaxin protein (on the order of ng/ml). The eotaxin generation was induced by tumour necrosis factor α (TNF-α) or IL-4, and the production was drastically increased by combined use of these cytokines. Because fibroblasts are ideally situated within the interstium at the sites of allergic responses, our finding that these cells represent an important cellular source of eotaxin suggests that fibroblast-derived eotaxin may act to regulate eosinophil recruitment in a paracrine fashion.

Binding of Long-Term Glycated Low Density Lipoprotein and Age- Albumin by Peripheral Monocytes and Endothelial Cells

Modification of low density lipoprotein (LDL) and plasma or tissue proteins by non-enzymatic glycation culminating in the formation of advanced glycation endproducts (AGEs) is one of the essential pathomechanisms leading to diabetes-associated long-term complications. We compared binding of glycated, glycoxidated and oxidated LDL by peripheral monocytes in activated and quiescent form. Interaction via specific receptors was different for glycated as compared to (glyc)oxidated LDL-modifications. In addition, binding of glycated LDL to quiescent and activated human umbilical vein endothelial cells was studied. In patients with insulin-dependent diabetes mellitus (IDDM), AGE-binding was significantly increased as compared to healthy individuals. Specific and non-specific monocyte binding mechanisms were detected, and both were significantly increased in IDDM patients. Specific and non-specific binding strategies possibly act in concert to eliminate circulating AGEs, which are instrumental in the development and progress of microangiopathic and macroangiopathic complications of diabetes mellitus.

Glomerular endothelial cells synthesize collagens but little gelatinase A and B.

Mesangial sclerosis is a major feature of progressive renal disease. The mesangium contains mesangial cells and is bounded by the peripheral glomerular basement membrane and endothelial cells. Mesangial cells synthesize and degrade extracellular matrix. Whereas both mesangial and endothelial cells synthesize extracellular matrix components, the degradative pathway, well studied in the former, has not been investigated in endothelial cells. This study examines lines of all three glomerular cell types derived from female B6SJLF1/J mice, as well as mRNA levels for collagens alpha1(I), alpha1(IV), alpha3 (IV), alpha5 (IV), and alpha1 (VI), laminin, tenascin, matrix metalloproteinase-2 (MMP-2), and MMP-9. Type I and IV collagen synthesis was confirmed by enzyme-linked immunosorbent assay. MMP-2 and MMP-9 enzyme activity was measured by zymography. It was found that glomerular endothelial cells are a significant source of collagens, laminin, and tenascin. However, they express only low levels of MMP-2 and no detectable MMP-9. Stimulation with exogenous transforming growth factor-beta1 leads to a significant increase in collagen I, tissue inhibitors of metalloproteinase-1, and MMP-9 in conditioned media. These data suggest that glomerular endothelial cells may play an active role in extracellular matrix remodeling in glomerular disease.

Expression of G-protein subtypes in cultured cerebral endothelial cells

This paper describes Western-blotting evidence for the presence of various guanine nucleotide binding proteins, G-proteins in cultured rat cerebral endothelial cells (CECs) and two immortalized cerebral endothelial cell lines, RBE4 and GP8. By using specific antibodies raised against known sequences of appropriate G-protein types that were previously characterized, we demonstrated the presence of Gsalpha, Gi2alpha, Gi3alpha, Gq/11alpha, Goalpha and Gbeta in cell lysates of primary cultures of CECs, and plasma membranes of RBE4 and GP8 cells. The appearance of Goalpha proteins in CECs might be of special importance, since they were not detected in peripheral endothelial cells in previous studies. Isoproterenol and bradykinin displayed significant, dose-dependent stimulation of [35S]GTPgammaS binding above basal values. This assay, reflecting the GDP-GTP exchange reaction on Galpha-subunits by receptor agonists, suggested that there were functional, G-protein coupled beta-adrenergic and bradykinin receptors in these systems. No significant stimulation of [35S]GTP7gammaS binding was noted with serotonin under our experimental conditions. Since stimulation of [35S]GTPgammaS binding by isoproterenol and bradykinin was additive, it was concluded that different Galpha proteins were activated by these two ligands. In analogy to other systems, activation of Gs is most likely by isoproterenol, while Gi and/or Gq/11 proteins might be activated by bradykinin receptors. The possible significance of the receptors and G-proteins detected is being discussed in the functioning of cerebral endothelium, and thus the blood-brain barrier.

Regulation of C1 Inhibitor Synthesis

The primary biologic roles of C1 inhibitor (C1-INH) are the regulation of activation of the classical complement pathway and of the contact system of kinin formation. Heterozygosity for deficiency or dysfunction of C1-INH results in hereditary angioedema (HAE). This deficiency results in loss of homeostasis with unregulated complement and contact system activation. Due to the consequent C1-INH consumption, plasma levels of C1-INH in patients with HAE are decreased below 50% of normal. In addition, diminished synthesis contributes to the lowered levels in some patients. The hepatocyte is the primary source of C1-INH, although a number of other cell types, including peripheral blood monocytes, microglial cells, fibroblasts, endothelial cells, the placenta, and megakaryocytes also synthesize and secrete the protein both in vivo and in vitro. Interferon-γ and α (IFN), colony stimulating factor-1, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) all induce C1-INH synthesis in a variety of cell types. The IFN-response elements in the 5'-flanking region and in the first intron have been partially characterized, as have several of the promoter elements that direct basal transcription of the gene. However, although androgen therapy, in vivo, results in an increase in C1-INH plasma levels, a direct effect of androgens on C1-INH synthesis has not been convincingly demonstrated. Although the C1-INH gene contains a potential glucocorticoid/androgen response element, this element does not appear to respond to androgen. Continued analysis of the transcriptional regulation of the C1-INH gene may lead to new approaches to therapy of HAE.

Cloning of vascular adhesion protein 1 reveals a novel multifunctional adhesion molecule.

Vascular adhesion protein 1 (VAP-1) is a human endothelial sialoglycoprotein whose cell surface expression is induced under inflammatory conditions. It has been shown previously to participate in lymphocyte recirculation by mediating the binding of lymphocytes to peripheral lymph node vascular endothelial cells in an L-selectin-independent fashion. We report here that the VAP-1 cDNA encodes a type II transmembrane protein of 84.6 kD with a single transmembrane domain located at the NH2-terminal end of the molecule and six potential N-glycosylation sites in the extracellular domain. In vivo, the protein exists predominantly as a homodimer of 170-180 kD. Ax endothelial cells transfected with a VAP-1 cDNA express VAP-1 on their cell surface and bind lymphocytes, and the binding can be partially inhibited with anti-VAP-1 mAbs. VAP-1 has no similarity to any currently known adhesion molecules, but has significant identity to the copper-containing amine oxidase family and has a monoamine oxidase activity. We propose that VAP-1 is a novel type of adhesion molecule with dual function. With the appropriate glycosylation and in the correct inflammatory setting, its expression on the lumenal endothelial cell surface allows it to mediate lymphocyte adhesion and to function as an adhesion receptor involved in lymphocyte recirculation. Its primary function in other locations where it is expressed, such as smooth muscle, may depend on its inherent monoamine oxidase activity.

Experimental infusion phlebitis: tolerance osmolality of peripheral venous endothelial cells.

This study aimed to determine the osmolality that peripheral venous endothelial cells can tolerate and to clarify the relationship between tolerance osmolality and duration of infusion. Nutrient solutions of 539-917 mOsm/kg, prepared to have no acidic effect, were infused into rabbit ear veins, and the veins were examined histopathologically. In each experiment of 8-, 12-, or 24-h infusion, the higher osmolality solutions caused some phlebitic changes, such as loss of venous endothelial cells, inflammatory cell infiltration, and edema; however, the lowest osmolality solution caused few changes. Infusion of 120 mL/kg of 814 mOsm/kg solution caused phlebitis at 5 or 10 mL.kg-1.h-1, however, the same volume of the same solution scarcely caused phlebitis at 15 mL.kg-1.h-1 because of the shortened infusion duration. These results suggest that the tolerance osmolality of peripheral venous endothelial cells with poor blood flow is about 820 mOsm/kg for 8 h, 690 mOsm/kg for 12 h, and 550 mOsm/kg for 24 h, and that the tolerance osmolality falls as the duration of infusion increases. In conclusion, hypertonic solutions should be infused at as high a rate as is clinically acceptable and compatible with nutrient bioavailability because increasing the infusion rate reduces the duration of infusion and phlebitis.

Inhibition of cytokine production and adhesion molecule expression by ibuprofen is without effect on transendothelial migration of monocytes.

The present study focusses on the effects of ibuprofen and its enantiomers on cytokine production by peripheral blood monocytes and endothelial cells as well as on the potential modulation of ADM-expression by human umbilical vein endothelial cells and the concomitant effects on monocyte transendothelial migration as measured by a cell migration assay system. This consists of an endothelial cell monolayer on a solid collagen substrate, i.e. an artificial vessel wall construct. We observed a significant inhibition by 100 microg/ml ibuprofen of VCAM-1 expression by endothelial cells while ELAM-1 and ICAM-1 expression was not influenced. However, we could not see any concomitant inhibitory effects on the spontaneous migration of monocytes after preincubating the endothelial cell monolayer with ibuprofen up to concentrations of 100 microg/ml and activating with suboptimal and optimal concentrations of TNF-alpha. Our monocyte transendothelial migration system reflects very sensitively endothelial cell-activation even by very low TNF-alpha concentrations. (S)- and (R)-ibuprofen were equal in their inhibitory/activating effects on cytokine production, with the exception of stronger IL-8 induction in endothelial cells by (R)-ibuprofen as compared to its chiral analogue.

Cell-to-cell and cell-to-matrix interactions mediate chemokine expression: an important component of the inflammatory lesion.

Although many studies have characterized soluble factors that stimulate or inhibit chemokine secretion, in this review we focus on the event of cellular adhesion as a novel mechanism for stimulating chemokine expression. Recent work has demonstrated chemokine expression following cell-to-cell and cell-to-matrix adhesion. The specificity of this finding was demonstrated utilizing various techniques that illustrate that adhesion, and not a soluble stimulus, is in some cases responsible for initiating or augmenting chemokine expression. For example, co-cultures of peripheral blood monocytes and endothelial cells secreted elevated levels of IL-8 and MCP-1 compared with either cell type alone. When co-cultured in transwells, this effect was significantly attenuated. In other experiments, neutralizing monoclonal antibodies to various adhesion molecules inhibited chemokine expression. The effects of adhesion were not limited to leukocytes. Both immune and non-immune cell types were evaluated as potential sources of adhesion-mediated chemokine expression. Not suprisingly, expression of some chemokines was associated with adhesion, whereas others were not, supporting the notion that adhesion differentially signals chemokine secretion during the inflammatory response. We hypothesize that as a recruited leukocyte encounters different adhesion substrates such as endothelial cells, basement membrane, extracellular matrix, and fibroblasts, the expression of chemokines from both the leukocyte and the substrate may be initiated, inhibited, or augmented. Careful characterization of the contribution of adhesion to regulation of chemokine expression will provide insight into the pathogenesis of many human diseases where chemokines have a central role.

Human cytomegalovirus infection of breast milk

Human cytomegalovirus is the most common cause of congenital and perinatal infections throughout the world. Primary infection with human cytomegalovirus usually follows a benign course, but the virus remains latent or persistent in the host cell thereafter. Understanding the epidemiology of human cytomegalovirus is a key element in the development of strategies for prevention of infection. Although the actual sites of latency or persistence of human cytomegalovirus infections are still controversial, peripheral blood mononuclear cells and endothelial cells appear to be major sites of infection. Persistent infections caused by human cytomegalovirus could be augmented by a decrease in major histocompatibility complex expression as well as by virus-mediated immune dysfunction. It is possible that specific cellular interactions as well as production of several cytokines are necessary for the reactivation of human cytomegalovirus. Breast-fed infants are susceptible to human cytomegalovirus infection from breast milk. Human cytomegalovirus was isolated more frequently from breast milk at more than 1 month after delivery than from colostrum or early breast milk. Human cytomegalovirus DNA was also not detected in colostrum, but was found in breast milk samples 1 month after delivery. To clarify the role of milk cells and whey in vertical infection by breast feeding, we separated breast milk into milk cells and whey and examined each fraction. Human cytomegalovirus was isolated more frequently from milk whey samples than from cell samples. Human cytomegalovirus particle shedding into whey may be more important in vertical infection by breast milk than cell-to-cell transmission. The supernatant of colostrum did not exert an inhibitory effect on human cytomegalovirus-infected cells. Serum levels of cell free soluble interleukin-2 receptor of mothers with DNA-positive milk at 1 month after delivery were significantly higher than those of mothers with DNA-negative milk. It is likely that levels of factors such as soluble interleukin-2 receptor in serum are related to the reactivation of human cytomegalovirus which occurs locally in the mammary gland of the lactating mother after delivery. This minireview focuses on recent advances in the study of human cytomegalovirus infection of breast milk.

Human cytomegalovirus infection of breast milk.

Human cytomegalovirus is the most common cause of congenital and perinatal infections throughout the world. Primary infection with human cytomegalovirus usually follows a benign course, but the virus remains latent or persistent in the host cell thereafter. Understanding the epidemiology of human cytomegalovirus is a key element in the development of strategies for prevention of infection. Although the actual sites of latency or persistence of human cytomegalovirus infections are still controversial, peripheral blood mononuclear cells and endothelial cells appear to be major sites of infection. Persistent infections caused by human cytomegalovirus could be augmented by a decrease in major histocompatibility complex expression as well as by virus-mediated immune dysfunction. It is possible that specific cellular interactions as well as production of several cytokines are necessary for the reactivation of human cytomegalovirus. Breast-fed infants are susceptible to human cytomegalovirus infection from breast milk. Human cytomegalovirus was isolated more frequently from breast milk at more than 1 month after delivery than from colostrum or early breast milk. Human cytomegalovirus DNA was also not detected in colostrum, but was found in breast milk samples 1 month after delivery. To clarify the role of milk cells and whey in vertical infection by breast feeding, we separated breast milk into milk cells and whey and examined each fraction. Human cytomegalovirus was isolated more frequently from milk whey samples than from cell samples. Human cytomegalovirus particle shedding into whey may be more important in vertical infection by breast milk than cell-to-cell transmission. The supernatant of colostrum did not exert an inhibitory effect on human cytomegalovirus-infected cells. Serum levels of cell free soluble interleukin-2 receptor of mothers with DNA-positive milk at 1 month after delivery were significantly higher than those of mothers with DNA-negative milk. It is likely that levels of factors such as soluble interleukin-2 receptor in serum are related to the reactivation of human cytomegalovirus which occurs locally in the mammary gland of the lactating mother after delivery. This minireview focuses on recent advances in the study of human cytomegalovirus infection of breast milk.

In vitro and in vivo biological activities of a novel nonpolyglutamable anti-folate, MX-68

MX-68 is a newly synthesized anti-folate, chemically designed not to undergo intracellular polyglutamation and to have increased affinity to dihydrofolate reductase (DHFR). In the present study, we examined the in vitro and in vivo biological activities of MX-68 compared with methotrexate (MTX) which forms several polyglutamates intracellularly. MX-68 dose-dependently inhibited the proliferation of PHA-, anti-CD3-, or PMA plus ionomycin-stimulated peripheral blood mononuclear cells (PBMC) and endothelial cells (EC) from normal subjects as well as IL-1β- or TNFα-stimulated synovial fibroblastic cells (SC) from rheumatoid arthritis (RA) patients. Coaddition of folinic acid completely reversed the anti-proliferative effects of both MX-68 and MTX. Although the anti-proliferative activities of MX-68 were almost comparable to those of MTX, the washout study clearly showed the characteristic nature of MX-68. When drugs were removed during culture, the suppressive effect of MX-68 completely disappeared, whereas suppression by MTX was merely weakened. MX-68 dramatically suppressed the onset of collagen-induced arthritis (CIA) in mice when the drug was orally administered three times a week, starting from the day of first immunization. In this model, 2 mg/kg of MX-68 was sufficient to completely suppress arthritis, whereas suppression by the same dose of MTX was partial. These lines of evidence suggest that polyglutamation is not always a prerequisite in the anti-rheumatic effects of anti-folate. In addition, since intracellular accumulation of polyglutamates is thought to have adverse effects, MX-68 may become a more potent and less toxic anti-rheumatic drug than MTX.

The Effect of Photorefractive Keratectomy on the Corneal Endothelium

The authors prospectively investigated the effect of excimer laser photorefractive keratectomy (PRK) for myopia on the corneal endothelium. Quantitative computer-assisted morphometric analysis of central and peripheral corneal endothelial cells was performed on 142 myopic eyes before and at 3 months, 1 year, and 2 years after PRK. The mean age of the subjects was 37 years (range, 21-66 years). Ninety-one (64%) of them had a history of contact lens wear. Mean attempted correction was -3.9 diopters (range, -1.6 to -6.0 diopters). The mean preoperative endothelial cell density was 2660 cells/mm2 centrally and 2776 cells/mm2 peripherally. There was no change in central endothelial cell density at any of the postoperative examinations. The peripheral cell density decreased 4.1% (P = 0.003) at 3 months and 6.2% (P = 0.0001) at 1 year. However, the peripheral cell density was not significantly different from the preoperative value at 2 years. The peripheral coefficient of variation of cell size was 7.8% lower 2 years postoperatively than it was preoperatively, and this improvement was attributable to cessation of contact lens wear after PRK. The decrease in peripheral endothelial cell density at 1 year correlated with the amount of attempted correction, but there was no correlation between attempted correction and the change in central or peripheral endothelial cell density 2 years postoperatively. For the correction of up to 6.0 D of myopia, PRK causes no detectable changes in central corneal endothelial cell density, but it does cause a transient, modest loss of peripheral corneal endothelial cells at 1 year. Variations in endothelial cell shape caused by contact lens wear resolve after PRK.