Serum vimentin predicts mortality in pediatric severe sepsis: A prospective observational study

OBJECTIVES

Vascular hyperpermeability by loss of endothelial barrier integrity is a hallmark of sepsis. Vimentin is involved in the regulation of the endothelial function and inflammatory response. However, the serum level of vimentin and its clinical relevance in pediatric severe sepsis (PSS) remain unknown.

METHODS

We conducted a prospective study of PSS cases who were admitted to the pediatric intensive care unit (PICU) from January 2018 to December 2020.

RESULTS

A total of 108 patients with PSS with a median age of 19.5 month were enrolled. The hospital mortality rate was 19.44% (21/108). Comparing with healthy controls, serum vimentin levels on PICU admission were significantly higher in patients with PSS (P < 0.001). The area under the ROC curve for vimentin to predict the hospital mortality was 0.712 (95% CI: 0.578-846) with a sensitivity of 71.43% and a specificity of 70.11%. Moreover, hospital mortality was significantly higher in patients with vimentin level over the cutoff value of 24.53 ng/ml than in patients with vimentin level below 24.53 ng/ml (P < 0.001).

CONCLUSIONS

Serum vimentin level as an indicator of endothelial injury is associated with the prognosis of PSS, and serum vimentin level ≥24.53 ng/ml on PICU admission predicts high risk for hospital mortality in PSS.

Oxidized LDL induces vimentin secretion by macrophages and contributes to atherosclerotic inflammation

Activated macrophages show increased expression of vimentin, an intermediate filament protein. Macrophages secrete vimentin into extracellular space; however, the functions of extracellular vimentin and the process of vimentin secretion are not clearly defined. We found that oxidized low-density lipoproteins (oxLDL) via CD36 induced vimentin secretion in macrophages. We also revealed that extracellular vimentin induced macrophages to release inflammatory cytokines and augmented oxLDL-induced release of TNF-α and IL-6. Extracellular vimentin activated NF-κB signaling via phosphorylation of focal adhesion kinase (p-FAK) and IκB kinase (p-IκK). Extracellular vimentin also amplified the oxLDL-induced p-IκK increase and IκB decrease. Vimentin-induced TNF-α release was not dependent on Dectin-1, which is known to bind vimentin. We measured serum vimentin concentrations and found that patients with atherosclerotic coronary artery disease had higher levels of serum vimentin than normal subjects. Circulating oxLDL and vimentin concentrations showed a high degree of correlation. In mouse experiments, vimentin concentration was higher in the sera of apoE null mice with western diet-induced atherosclerosis than in the sera of chow diet-fed apoE null mice without atherosclerosis. We concluded that vimentin is secreted by oxLDL/CD36 interaction in macrophages and extracellular vimentin promotes macrophage release of pro-inflammatory cytokines. This may contribute to atherosclerotic inflammation and based on our analysis of serum vimentin, we suggest serum vimentin as a predictive marker for atherosclerosis. KEY MESSAGES: OxLDL via CD36 induces secretion of vimentin, a cytoskeletal protein in macrophages. Extracellular vimentin induces macrophages to release proinflammatory cytokines such as tumor necrotizing factor-alpha (TNF-α) and this process is mediated by activation of focal adhesion kinase (FAK) and NF-ƙB signaling. Serum concentrations of vimentin in coronary artery disease patients are higher than that in control group. Vimentin concentration is strongly correlated with oxLDL concentration in serum.

EVALUATING MMP-2 AND TGFß-RI EXPRESSION IN CIRCULATING TUMOR CELLS OF PANCREATIC CANCER PATIENTS AND THEIR CORRELATION WITH CLINICAL EVOLUTION

BACKGROUND

Metastasis is common in the diagnosis of pancreatic cancer, and the presence of epithelial-mesenchymal transition markers in circulating tumor cells may suggest worse prognosis.

AIM

To correlate the number of circulating tumor cells (CTCs) in the peripheral blood of patients with a locally advanced or metastatic pancreatic tumor and the protein expression involved in epithelial-mesenchymal transition (EMT) in CTCs with clinical characteristics, progression-free survival (PFS) and overall survival (OS).

METHOD

This was a prospective study conducted using peripheral blood samples collected at three different times. CTCs were quantified by the ISET test and analyzed by immunocytochemistry. Proteins involved in EMT (vimentin, TGFß-RI and MMP2) were analyzed in all CTCs.

RESULTS

Twenty-one patients were included. Median CTCs detected were 22, 20 and 8 CTCs/8 ml blood at baseline, first and second follow-up, respectively. No statistically significant correlation was found in correlating the number of CTCs and the evaluated clinical characteristics, PFS, or OS. There was no difference in PFS and OS among the EMT markers in the groups with and without markers.

CONCLUSION

CTC analysis was not relevant in this sample for comparing clinical findings, PFS and OS in patients with pancreatic cancer. However, marker analysis in CTCs could be useful for the MMP-2 and/or TGFß-RI expression, as observed by the separate PFS curve.

Detection of circulating tumor cells from cryopreserved human sarcoma peripheral blood mononuclear cells

Circulating tumor cells (CTCs) enter the vasculature or lymphatic system after shedding from the primary tumor. CTCs may serve as "seed" cells for tumor metastasis. The utility of CTCs in clinical applications for sarcoma is not fully investigated, partly owing to the necessity for fresh blood samples and the lack of a CTC-specific antibody. To overcome these drawbacks, we developed a technique for sarcoma CTCs capture and detection using cryopreserved peripheral blood mononuclear cells (PBMCs) and our proprietary cell-surface vimentin (CSV) antibody 84-1, which is specific to tumor cells. This technique was validated by sarcoma cell spiking assay, matched CTCs comparison between fresh and cryopreserved PBMCs, and independent tumor markers in multiple types of sarcoma patient blood samples. The reproducibility was maximized when cryopreserved PBMCs were prepared from fresh blood samples within 2 h of the blood draw. In summary, as far as we are aware, ours is the first report to capture and detect CTCs from cryopreserved PBMCs. Further validation in other types of tumor may help boost the feasibility and utility of CTC-based diagnosis in a centralized laboratory.

[The clinical informativeness of detection of antibodies to citrullinated proteins under rheumatoid arthritis]

The main diagnostic laboratory markers of rheumatoid arthritis are IgM rheumatoid factor and antibodies to citrullinated proteins. The IgM rheumatoid factor is a sensitive but insufficiently specific marker of rheumatoid arthritis. The antibodies to citrullinated proteins have a higher specificity for diagnostic of rheumatoid arthritis. The antibodies to cyclic citrullinated peptide and modified citrullinated vimentin are the main representatives of family of antibodies to citrullinated proteins applying in clinical diagnostic practice. The study was carried out to deternine the role of antibodies to citrullinated proteins and modified citrullinated vimentin in diagnostic, evaluation of activity and severity of destructive alterations under rheumatoid arthritis. The samplings of 993 patients with reliable diagnosis of rheumatoid arthritis. 179 patients with other rheumatoid diseases and 30 healthy donors were examined. The measurement of serum concentration of IgM rheumatoid factor and C-reactive protein was implemented by immune nephelometric analysis and antibodies to citrullinated proteins were analyzed by enzymoimmunoassay The erythrocyte sedimentation rate was established using the Westergreen technique. It was established that antibodies to modified citrullinated vimentin had the highest diagnostic specificity (83%), antibodies to cyclic citrullinated peptide had the highest diagnostic specificity (87%). The diagnostic specificity of joint detection of IgM rheumatoid factor, antibodies to citrullinated proteins and antibodies to modified citrullinated vimentin made up to 87%. In patients negative to rheumatoid factor the rate ofdetection of antibodies to citrullinated proteins made up to 34% and antibodies to modified citrullinated vimentin made up to 48%. The diagnostic effectiveness of detection of antibodies to citrullinitted proteins (ratio of likelihood of positive and negative results of test was correspondingly 5.5 and 0.3; area under ROC curve 0.8) and antibodies to modified citrullinated vimentin (ratio of likelihood of positive and negative results of test was correspondingly 4.4 and 0.2; area under ROC curve 0.9) surpassed the same in analysis of IgM rheumatoid factor (ratio of likelihood of positive results--3.2, ratio of likelihood of negative results--0.4, area under ROC curve--0.8). The weak positive correlation relationship was established between concentration of antibodies to cyclic citrillinatedpeptide/antibodies to modified citrullinated vimentin in blood serum and indicators of clinical laboratory activity of rheumatoid arthritis (ESR, CRP DAS 28, (r-0.2. p < 0.05). The high positive levels of antibodies to modified citrullinated vimentin associated with expressed destructive affection of joints (p < 0.02). The antibodies to cyclic citrullinated peptide are the most highly specific and clinically informative laboratory diagnostic marker of rheumatoid arthritis. The detection of antibodies to modified citrullinated vimentin is an important additional serological test to diagnose rheumatoid arthritis in IgM rheumatoid factor-negative and/or antibodies to cyclic citrullinated peptide-negative patients and to forecast severe destructive affection of joints under the given disease. The joint study of IgM rheumatoid factor, antibodies to cyclic citrullinated peptide and antibodies to modified citrullinated vimentin under rheumatoid arthritis has higher diagnostic sensitivity as compared with isolated antibodies to citrullinated proteins.

Heterogeneous atypical cell populations are present in blood of metastatic breast cancer patients

INTRODUCTION

Circulating tumor cells (CTCs) are commonly isolated from the blood by targeting the epithelial cell adhesion molecule (EpCAM) through positive selection. However, EpCAM can be downregulated during metastatic progression, or it can be initially not present. We designed the present prospective trial to characterize CTCs as well as other circulating cell populations in blood samples from women with metastatic breast cancer without EpCAM-dependent enrichment and/or isolation technology.

METHODS

A total of 32 patients with metastatic breast cancer were enrolled, and blood samples were processed using a previously described negative depletion immunomagnetic methodology. Samples from healthy volunteers were run as controls (n = 5). Multistep sequential labeling was performed to label and fix cell-surface markers followed by permeabilization for cytokeratins (CK) 8, 18 and 19. Multiparametric flow cytometry (FCM) analysis was conducted using a BD LSR II flow cytometer or a BD FACSAria II or FACSAria III cell sorter. Immunocytochemical staining on postenrichment specimens for DAPI, EpCAM, CD45, CK, epidermal growth factor receptor and vimentin was performed. Expression of these markers was visualized using confocal microscopy (CM).

RESULTS

CD45-negative/CK-positive (CD45- CK+) populations with EpCAM + and EpCAM - expression were identified with both FCM and CM from the negatively enriched patient samples. In addition, EpCAM + and EpCAM - populations that were CK + and coexpressing the pan-hematopoietic marker CD45 were also noted. There were more CK + EpCAM - events/ml than CK + EpCAM + events/ml in both the CD45- and CD45+ fractions (both statistically significant at P ≤ 0.0005). The number of CK + CD45- and CK + CD45+ events per milliliter in blood samples (regardless of EpCAM status) was higher in patient samples than in normal control samples (P ≤ 0.0005 and P ≤ 0.026, respectively). Further, a significant fraction of the CK + CD45+ events also expressed CD68, a marker associated with tumor-associated macrophages. Higher levels of CD45-CK + EpCAM - were associated with worse overall survival (P = 0.0292).

CONCLUSIONS

Metastatic breast cancer patients have atypical cells that are CK + EpCAM - circulating in their blood. Because a substantial number of these patients do not have EpCAM + CTCs, additional studies are needed to evaluate the role of EpCAM - circulating cells as a prognostic and predictive marker.

Antigen-specificity of oligoclonal abnormal protein bands in multiple myeloma after allogeneic stem cell transplantation

Myeloma patients may develop oligoclonal immunoglobulins, so-called abnormal protein bands (APB), after stem cell transplantation. APB do not correspond to the patient's paraprotein and confer a good prognosis. We set out to investigate whether such APB represent a humoral anti-myeloma immune response by screening immunoglobulins of 15 myeloma patients after allogeneic stem cell transplantation and a control group of healthy donors for reactivity with myeloma protein extracts. While the immunoglobulins of healthy donors did not react with myeloma protein extracts, patient-derived immunoglobulins showed variable levels of interaction, depending on the presence of APB on immunofixation. Most commonly, we detected interactions with heat-shock proteins, followed by neutral alpha-glucosidase, alpha-enolase and vimentin, as well as proliferating cell nuclear antigen and MAGEA4. More than 80% of targets were upregulated in myeloma. Heat-shock protein 60 (HSP60) was subsequently evaluated as an exemplary antigen. We found that HSP60 was aberrantly displayed on the surface of primary myeloma cells. Indeed, patient-derived APB-containing immunoglobulins recognized surface HSP60 suggesting that this antigen becomes accessible to the immune system after aberrant membrane exposition. We conclude that immunoglobulin fractions with APB recognize recurrent myeloma antigens and that this humoral response may contribute to the more favorable prognosis in patients with APB.

Colon cancer at the molecular level--usefulness of epithelial-mesenchymal transition analysis

Colorectal cancer (CRC) is the third form of cancer in both men and women. In Romania, the incidence of CRC in 2000 is 17.74 %ooo, in 2002 becoming the second cause of death. We reviewed a series of studies that are related to colon cancer and studied the epithelial-mesenchymal transition at the front of tumor invasion (EMT). Cellular phenotypic changes characteristic of EMT can be induced by the absence of transition cofactor (p300) involved in cellular regulation. Loss of syndecan-l marker is associated with local tumor stage and metastasis. Modulators of protein kinase resistance was associated with changes in genes involved in EMT (including vimentin hyperexpression) and genes involved in invasion (N-cadherin) with a decrease expression of genes involved in epithelial cell adhesion (E-cadherin). Progression in colon cancer is characterized by activating mutations in Ras genes and tumor growth factor action. Vimentin expression associated with EMT initiates molecular program. One of the characteristics of EMT is the loss of E-cadherin. TGF-p (transforming growth factor beta) induces epithelial-mesenchymal transition in colon cancer cell lines with the microsatellite stability, inducing cell invasion and migration. EMT is a critical early event involved in invasion and metastasis of colorectal cancer, characterized by the presence of markers specific to each phenotype, epithelial or mesenchymal. Multiple biomarkers involved in the induction of EMT may represent future therapeutic target in the treatment of colonic neoplasia.

Discovery of lamin B1 and vimentin as circulating biomarkers for early hepatocellular carcinoma

The recent advancements in proteomic technologies have reconstituted our research strategies over different type of liver diseases including hepatocellular carcinoma (HCC). Combined analyses on HCC proteome and clinicopathological data of patients have allowed identification of many promising biomarkers that can be further developed into noninvasive diagnostic assays for cancer surveillance. Capitalizing our established proteomic platform primarily based on two-dimensional polyacrylamide gel electrophoresis (2DE) and MALDI-TOF/TOF mass spectrometry, our groups have identified lamin B1 (LMNB1) and vimentin (VIM) as promising biomarkers for detection of early HCC. Protein levels of both biomarkers were significantly elevated in cancerous tissues when compared to the controls in disease-free and cirrhotic liver subjects. Further investigation of the circulating LMNB1 mRNA level in patients' blood samples by standard PCR showed 76% sensitivity and 82% specificity for detection of early HCC. In parallel, an ELISA assay for measuring circulating vimentin level in patients' serum samples could detect small HCC at 40.91% sensitivity and 87.5% specificity. The candidate biomarkers were evaluated with the diagnostic performance of α-fetoprotein (AFP) for HCC. In this article, we address the current protocols for HCC biomarker discovery, ranging from clinical sample preparation, 2DE proteomic profiling and informatics analysis, and assay development and clinical validation study. Focus is emphasized on the methods for sample preservation and low-abundance protein enrichment.

[Methotrexate-induced changes in the concentration of antibodies to mutaded citrullinated vimentin in blood serum of patients with rheumatoid arthritis]

AIM

To study effects of methotrexate on the titer of antibodies to mutated citrullinated vimentin (anti-MCV) and ascertain possibility of using this marker for control of treatment results and choice of individual effective dose of the drug.

MATERIAL AND METHODS

A 12-month trial included 76 patients with verified rheumatoid arthritis (RA). Methotrexate per os was given in a dose 7.5-10 mg/week to 44 (57.9%) patients, 25 patients received no basic therapy. Anti-MCV (IU/ml) were detected with commercial chemicals made in Germany (ORGENTEC).

RESULTS

RA patients given methotrexate doses 7.5 and 10 mg/week and untreated with basic anti-inflammatory drugs showed no significant differences by basic clinical and device parameters, level of anti-MCV at primary examination and 12 months later.

CONCLUSION

Anti-MCV titer cannot be used for control of efficacy of methotrexate treatment in doses 75 and 10 mg/week, choice of individual effective doses.

Detection of vimentin (VIM) methylation in the serum of colorectal cancer patients

AIM

Detection of colorectal cancer using serum assay of vimentin methylation.

MATERIALS AND METHODS

We attempted to detect vimentin methylation in the serum of colorectal cancer patients using quantitative methylation-specific polymerase chain reaction (qMSP).

RESULTS

Of 44 colorectal cancer patients, 4 (9%) exhibited methylation of the vimentin gene in their serum DNA by qMSP. Interestingly, methylation was significantly found in the serum of patients with liver metastasis, peritoneal dissemination, and distant metastasis (p = 0.026, p = 0.0029 and p = 0.0063, respectively), suggesting that vimentin methylation in serum might be detected more frequently in patients with advanced colorectal cancer.

CONCLUSION

The high sensitivity of qMSP makes it possible to detect smaller amounts of tumor DNA in the serum, suggesting that qMSP can be used as a screening method for cancer.

PDIA3, HSPA5 and vimentin, proteins identified by 2-DE in the valvular tissue, are the target antigens of peripheral and heart infiltrating T cells from chronic rheumatic heart disease patients

Rheumatic fever (RF) is a post-infectious autoimmune disease due to sequel of group A streptococcus (GAS) pharyngitis. Rheumatic heart disease (RHD), the major manifestation of RF, is characterized by inflammation of heart valves and myocardium. Molecular mimicry between GAS antigens and host proteins has been shown at B and T cell level. However the identification of the autoantigens recognized by B and T cells within the inflammatory microenvironment of heart tissue in patients with RHD is still incompletely elucidated. In the present study, we used two-dimensional gel electrophoresis (2-DE) and mass spectrometry to identify valvular tissue proteins target of T cells from chronic RHD patients. We could identify three proteins recognized by heart infiltrating and peripheral T cells as protein disulfide isomerase ER-60 precursor (PDIA3), 78kD glucose-regulated protein precursor (HSPA5) and vimentin, with coverage of 45%, 43 and 34%, respectively. These proteins were recognized in a proliferation assay by peripheral and heart infiltrating T cells from RHD patients suggesting that they may be involved in the autoimmune reactions that leads to valve damage. We also observed that several other proteins isolated by 2-DE but not identified by mass spectrometry were also recognized by T cells. The identified cardiac proteins are likely relevant antigens involved in T cell-mediated autoimmune responses in RF/RHD that may contribute to the development of RHD.

Clinical evaluation of anti-mutated citrullinated vimentin by ELISA in rheumatoid arthritis

OBJECTIVE

Anti-cyclic citrullinated peptide (CCP) antibodies have emerged as sensitive and specific serological markers of rheumatoid arthritis (RA). However, antibodies to several other citrulline-containing proteins, including citrullinated fibrin and vimentin, have been detected in patients with RA, suggesting that citrulline is an essential constituent of autoantigens for RA-specific autoantibodies. We examined the diagnostic performance of the newly developed anti-mutated citrullinated vimentin (MCV) antibody assay.

METHODS

Concentrations of anti-MCV, anti-CCP2, and rheumatoid factors (RF) were determined in the sera of 237 individuals: 119 patients with RA and 118 controls, including patients with other rheumatic diseases and healthy subjects. Diagnostic properties were compared by receiver-operating characteristic curve analysis.

RESULTS

Using manufacturer's recommended cutoff values, sensitivity and specificity of anti-MCV antibodies were 75.6% and 91.5% in RA, compared to 66.4% and 98.3% for anti-CCP2. Introducing cutoff values to obtain the same 95% specificity resulted in decreased sensitivity of the anti-MCV test (69.7%) and increased sensitivity of the anti-CCP2 test (74.8%). At optimal cutoff levels, 29.4% of IgM RF-negative cases as well as 13.3% of anti-CCP2-negative cases in the RA group were anti-MCV-positive. Double-positivity for anti-MCV and anti-CCP2 provided 98.3% specificity with 97.5% positive predictive value in RA.

CONCLUSION

Overall, the performance of the novel anti-MCV ELISA for the diagnosis of RA is similar to that of the anti-CCP2 test [area under the curve 0.853 (95% CI 0.801-0.905) vs 0.910 (95% CI 0.873-0.946); p not significant]. As the diagnostic spectrum of the anti-MCV assay is somewhat different from that of anti-CCP2, the combined application of the 2 assays can improve the laboratory diagnostics of RA.

Using smudge cells on routine blood smears to predict clinical outcome in chronic lymphocytic leukemia: a universally available prognostic test

Recently developed prognostic tests in early Rai and Binet stage chronic lymphocytic leukemia (CLL) require considerable technologic expertise and are not available worldwide. Smudge cells are CLL cells ruptured during smear preparation. We hypothesized that smudge cell formation is inversely correlated with expression of vimentin, a cytoskeletal protein and prognostic marker, and that the percentage of smudge cells would predict prognosis in CLL. We reviewed the blood smears of 75 patients with previously untreated early and intermediate-stage CLL (Rai stage 0-II) who were seen at the Mayo Clinic in Rochester, Minn, between September 1989 and December 2000. A total of 200 lymphocytes and smudge cells were counted on each slide and the results expressed as a percentage of the total lymphocytes (intact and smudged). The median percentage of smudge cells was 27% (range, 4%-72%). The percentage of smudge cells inversely correlated with vimentin expression (r=-0.57; P=.007). The median percentage of smudge cells was higher in patients with the mutated immunoglobulin heavy chain gene than in those with the unmutated immunoglobulin heavy chain gene (31% vs 13%; P=.02). Patients with less than 30% smudge cells had a median time from diagnosis to initial treatment of 72.7 months, whereas the median time from diagnosis to initial treatment in patients with 30% or more smudge cells was not reached (P=.001). The percentage of smudge cells as a continuous variable correlated with overall survival (P=.04). The estimation of smudge cells on a blood smear could be a universally available prognostic test in early-stage CLL.

Use of proteomic analysis of endometriosis to identify different protein expression in patients with endometriosis versus normal controls

OBJECTIVE

To use proteomic techniques, including two-dimensional electrophoresis (2-DE), Western blot, and mass spectrometry, to screen and identify proteins that were expressed differently in patients with endometriosis versus normal controls.

DESIGN

First, we aimed to find a difference in the way serum and eutopic endometrial proteins were expressed in women with and without endometriosis. Second, we were interested in searching for endometriotic proteins, which were specifically recognized by sera from patients with endometriosis.

SETTING

Collaborative investigation in an academic research environment.

PATIENT(S)

Consenting women of reproductive age taking no medications and with laparoscopically proven endometriosis.

INTERVENTION(S)

Surgical excision of eutopic and ectopic endometrial biopsy and phlebotomization of patients with endometriosis and controls.

MAIN OUTCOME MEASURE(S)

Protein expression.

RESULT(S)

Thirteen protein spots from serum correlated with 11 known proteins and 11 protein spots from endometrium correlated with 11 known proteins were found differently expressed between women with and without endometriosis. Some proteins may be cytoskeletons, and some may be involved in the regulation of cell cycle, signal transduction, or immunological function. Three proteins, which were identified as vimentin, beta-actin, and ATP synthase beta subunit, hybridized significantly differently between endometriosis sera and normal sera.

CONCLUSION(S)

The data help to establish a human endometriosis proteome database and broaden our understanding of the pathogenesis of endometriosis. Further study of the proteins identified herein will assist in the eventual development of new diagnoses and treatments for endometriosis.

The endothelial cell-specific antibody PAL-E identifies a secreted form of vimentin in the blood vasculature

During mammalian vascular development, endothelial cells form a complex array of vessels that differ markedly in structure and function, but the molecular basis for this vascular complexity is poorly understood. Recent insights into endothelial diversity have come from the identification of molecular markers expressed on distinct endothelial cell populations. One such marker, the PAL-E antibody, has been used for almost 20 years to distinguish blood and lymphatic vessels, but the identity of the protein recognized by PAL-E has been unknown. In the present study we have used protein purification and tandem mass spectrometry analysis of tryptic peptides to identify the PAL-E antigen as a secreted form of vimentin. Vimentin has been well characterized as an intracellular intermediate filament protein expressed broadly in mesenchymal cells. In contrast, PAL-E-reactive vimentin is secreted extracellularly, its synthesis is restricted to a distinct population of blood endothelial cells and activated macrophages, and PAL-E-reactive vimentin is found in circulating human blood. PAL-E-reactive vimentin does not arise from an endothelial cell-specific mRNA transcript but is the product of cell-specific posttranslational modification. The PAL-E antibody therefore defines secretion of vimentin as a molecular distinction among endothelial cells and exposes a novel, extracellular role for vimentin in the blood vasculature.

Phase I and pharmacologic study of the human DNA methyltransferase antisense oligodeoxynucleotide MG98 given as a 21-day continuous infusion every 4 weeks

PURPOSE

MG98 is a second generation phosphorothioate antisense oligodeoxynucleotide which is a highly specific inhibitor of translation of the mRNA for human DNA MeTase I (DNMT 1). This phase I study examined the toxicity and pharmacologic profile of MG98 administered as a continuous 21-day intravenous infusion every 4 weeks.

PATIENTS AND METHODS

Fourteen patients with solid cancers received a total of 25 cycles of MG98 at doses ranging from 40 to 240 mg/m2/day. Steady-state concentrations of MG98 were measured as were several pharmacodynamic assessments including mRNA of the target gene, DNMT1, in PBMC. In addition, other potential surrogate markers of drug effects were explored, including hemoglobin F, Vimentin and GADD45.

RESULTS

Dose limiting effects were drug-related reversible transaminase elevation and fatigue seen at doses of 240, 200 and 160 mg/m2/day. The dose level of 80 mg/m2/day was felt to be safe and tolerable when delivered on this schedule. No evidence of antitumor activity was observed. Although pharmacokinetic analysis revealed that at the higher dose levels, mean Css values of MG98 were approximately 10-fold times the IC50 values associated with target inhibition in vitro, the extent of MG98 penetration into target tumors in this trial was not determined. No consistent, dose-related changes in correlative markers including DNMT1 mRNA, hemoglobin F, Vimentin and GADD45, were observed.

CONCLUSIONS

This schedule of MG98 given as a 21-day continuous intravenous infusion every 4 weeks was poorly tolerated in the highest doses; therefore, further disease-site specific evaluation of the efficacy of this agent will utilize a more favorable, intermittent dosing schedule. Pharmacodynamic evaluations undertaken in an attempt to explore and validate the biological mechanisms of MG98 did not show dose-related effects.

Gamma-tubulin in chicken erythrocytes: changes in localization during cell differentiation and characterization of cytoplasmic complexes

The mechanism of marginal band (MB) formation in differentiating erythroid cells is not fully understood, and the proteins involved in nucleation of MB microtubules are largely unknown. To gain insights into the function of gamma-tubulin in MB formation, we have followed its distribution in developing chicken erythrocytes and characterized soluble forms of the protein. In early stages of erythroid cells differentiation, gamma-tubulin was present in microtubule-organizing centers, mitotic spindles, as well as on MB. Its subcellular localization changed in the course of differentiation, and in postnatal peripheral erythrocytes gamma-tubulin was found only in soluble forms. After cold-induced depolymerization gamma-tubulin in erythroid cells formed large clusters that were not observed in matured cells, and re-growth experiments demonstrated that gamma-tubulin was not present in distinct nucleation structures at the cell periphery. Soluble gamma-tubulin formed complexes of various size and large complexes were prone to dissociation in the presence of high salt concentration. Interaction of gamma-tubulin with tubulin dimers was revealed by precipitation experiments. gamma-Tubulin occurred in multiple charge variants whose number increased in the course of erythrocyte differentiation and corresponded with decreased binding to MB. The presented data demonstrate for the first time that gamma-tubulin is a substrate for developmentally regulated posttranslational modifications and that the binding properties of gamma-tubulin or its complexes change during differentiation events.

Rigidity of circulating lymphocytes is primarily conferred by vimentin intermediate filaments

Lymphocytes need rigidity while in circulation, but must abruptly become deformable to undergo transmigration into tissue. Previously, the control of leukocyte deformability has been attributed to microfilaments or microtubules, but the present studies demonstrate the greater importance of vimentin intermediate filaments (IFs). In circulating T lymphocytes, IFs form a distinctive spherical cage that undergoes a rapid condensation into a juxtanuclear aggregate during chemokine-induced polarization. Measurements of the resistance of peripheral blood T lymphocytes to global deformation demonstrate that their rigidity is primarily dependent on intact vimentin filaments. Microtubules, in contrast, are not sufficient to maintain rigidity. Thus, vimentin IFs are a primary source of structural support in circulating human lymphocytes, and their regulated collapse is likely to be an essential element in chemokine-induced transendothelial migration.

Chemotactic peptide-induced changes of intermediate filament organization in neutrophils during granule secretion: role of cyclic guanosine monophosphate

In neutrophils activated to secrete with formyl-methionyl-leucyl-phenylalanine, intermediate filaments are phosphorylated transiently by cyclic guanosine monophosphate (cGMP)-dependent protein kinase (G-kinase). cGMP regulation of vimentin organization was investigated. During granule secretion, cGMP levels were elevated and intermediate filaments were transiently assembled at the pericortex to areas devoid of granules and microfilaments. Microtubule and microfilament inhibitors affected intermediate filament organization, granule secretion, and cGMP levels. Cytochalasin D and nocodazole caused intermediate filaments to assemble at the nucleus, rather than at the pericortex. cGMP levels were elevated in neutrophils by both inhibitors; however, with cytochalasin D, cGMP was elevated earlier and granule secretion was excessive. Nocodazole did not affect normal cGMP elevations, but specific granule secretion was delayed. LY83583, a guanylyl cyclase antagonist, inhibited granule secretion and intermediate filament organization, but not microtubule or microfilament organization. Intermediate filament assembly at the pericortex and secretion were partially restored by 8-bromo-cGMP in LY83583-treated neutrophils, suggesting that cGMP regulates these functions. G-kinase directly induced intermediate filament assembly in situ, and protein phosphatase 1 disassembled filaments. However, in intact cells stimulated with formyl-methionyl-leucyl-phenylalanine, intermediate filament assembly is focal and transient, suggesting that vimentin phosphorylation is compartmentalized. We propose that, in addition to changes in microfilament and microtubule organization, granule secretion is also accompanied by changes in intermediate filament organization, and that cGMP regulates vimentin filament organization via activation of G-kinase.

Human glioma associated intermediate filament proteins: over-expression, co-localization and cross-reactivity

The identification of human brain tumor-associated markers could facilitate the development of new diagnostic and therapeutic strategies for these malignancies. The type III intermediate filament proteins (IFPs): vimentin, desmin and glial fibrillary acidic protein (GFAP) were studied in human glioma tissue extracts, in sera from glioma patients and in low passage glioma cell lines prepared from primary cultures of freshly dissected tumors. Radioimmunoassay (RIA) studies, using anti-GFAP, anti-desmin and anti-vimentin mAbs, showed high levels of these proteins in glioma extracts. Binding studies with authentic IFPs indicated the absence of circulating antibodies against these proteins in the sera of glioma patients. On the other hand, these sera showed high levels of vimentin. Binding studies with these antibodies using RIAs and western immunoblotting, showed that while anti-GFAF mAbs were specific to GFAP, anti-desmin mAb cross-reacted completely with GFAP, anti-vimentin mAb cross-reacted substantially with desmin and GFAP. Immunofluorescence staining of frozen sections revealed high levels of neurofilaments in gliomas and strikingly low levels in normal brain tissue. Double immunofluorescence staining showed co-occurrence of all three IFPs in the same filaments. This suggests either co-expression or cross-reactivity of these proteins due to their high degree of homology. Thus, caution should be exercised in the use and interpretation of immunohistochemical data using antibodies to IFs.

Evaluation of red blood cell lysing solutions for the detection of intracellular antigens by flow cytometry

When analyzing leukocyte cell surface antigens by flow cytometry, leukocytes are usually first labeled in whole blood and the red blood cells are finally lysed with lysing solutions. The erythrocytes are lysed, but the leukocytes are expected to remain intact. Six commercial red blood cell lysing methods were investigated for possible leukocyte permeabilization effect. The effectiveness of permeabilization was studied by propidium iodide staining, and the detectability of intracellular antigens was studied by using monoclonal antibodies toward two model antigens. Most of the lysing methods caused permeabilization of at least part of the leukocytes, but only one method, already found in our previous studies, was applicable for complete permeabilization of leukocytes and for detection of intracellular antigens alone or simultaneously with the cell surface antigens.

Cytoskeletal organization of peripheral blood normal and leukemic lymphocytes and lymphoblasts

Content of actin and vimentin and organization of actin were studied in peripheral blood lymphocytes from healthy donors, circulating lymphocytes from patients with chronic lymphocytic leukemia (CLL) and lymphoblasts from children with common acute lymphoblastic leukemia (c-ALL). Actin and vimentin were quantified as percentage of total proteins by densitometric scanning of SDS-polyacrylamide gels loaded with Triton-X-100 cell lysates. In addition, the amounts of F- and G-actin were evaluated by ultracentrifugation of total lysates prior to electrophoresis. Compared to peripheral blood lymphocytes from healthy donors, CLL lymphocytes, but not blasts expressing c-ALL antigen, show a decrease in total actin and vimentin contents. Analysis of SDS gels after ultracentrifugation shows that F-actin is diminished of about 50% in both CLL and ALL cells compared to peripheral lymphocytes from healthy donors. The changes in actin and vimentin content and of actin organization may account for some of the functional abnormalities observed in leukemic cell populations.

Platelet intermediate filaments: detection of a vimentinlike protein in human and bovine platelets

Human and bovine platelets contain a 58,000-dalton vimentinlike protein that cross-reacts with antivimentin antibody. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blots indicate that this protein is present in whole platelet lysates and triton insoluble cytoskeletons. Transmission electron microscopy of platelets reveals an isotropic network of individual intermediate filaments distributed throughout the platelets. High salt, triton extracted, glutaraldehyde and tannic acid fixed platelets reveal 10-nm filaments that can be seen to form a peripheral ring, as well as an isotropic network in the body of the cells. Indirect immunofluorescence of resting and spread platelets demonstrates a circumferential staining pattern close to the cell membrane, with additional fibrillar staining throughout the platelets. Our data suggest that the 58,000-dalton vimentinlike protein may be associated with the microtubule coil and the plasma membrane, and may thus help to maintain the resting platelet's discoid shape.