Biomedical subjects

J W Lammers

Publications and source records attributed to J W Lammers.

At least 19 recordsLinked to original sources

PubMed2001

[CBO guideline 'Oxygen therapy at home'].

In the Netherlands, domiciliary oxygen therapy is regularly prescribed incorrectly and thus inefficiently, and the policies surrounding this therapy are inconsistent. This applies particularly to patients with chronic hypoxaemia due to chronic obstructive pulmonary disease (COPD). In order to establish a scientific basis for a uniform prescription policy, guidelines have been developed under the auspices of the Dutch Thoracic Society with the support of the Dutch Institute for Health Care Improvement. Based on scientific research, recommendations have been formulated for the indications and aims of domiciliary oxygen therapy and long-term oxygen therapy (LTOT). The most important recommendations (summarised on the back of an oxygen application form) are: domiciliary oxygen therapy is only indicated for severe hypoxaemia by day at rest; if domiciliary oxygen therapy was prescribed following recovery from an acute exacerbation or hospitalisation, the arterial oxygen tension should be rechecked within three months of starting oxygen therapy; prescription of LTOT is only justified in case of an optimal (non-)medical regimen, clinical stability, and chronic hypoxaemia, and providing a number of preconditions, such as smoking cessation (partly due to the fire hazard), have been met; LTOT is a lifelong therapy that should be prescribed for at least 15, and preferably 24, hours per day, and the oxygen flow rate settings for rest, exertion and sleep should be adjusted to meet the patient's needs; for ambulatory patients, the prescribing physician should consider the portability of the oxygen equipment; as patient education and supervision are essential to secure the success of LTOT, the prescribing physician should cooperate with the general practitioner, the district nurse and the oxygen supplier in this respect.

Algorithms↗

PubMed2001

Cytokine-specific transcriptional regulation through an IL-5Ralpha interacting protein.

Cytokine receptors consist of multiple subunits, which are often shared between different receptors, resulting in the functional redundancy sometimes observed between cytokines. The interleukin 5 (IL-5) receptor consists of an IL-5-specific alpha-subunit (IL-5Ralpha) and a signal-transducing beta-subunit (betac) shared with the IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors. In this study, we sought to find a role for the cytoplasmic domain of IL-5Ralpha. We show that syntenin, a protein containing PSD-95/Discs large/zO-1 (PDZ) domains, associates with the cytoplasmic tail of the IL-5Ralpha. Syntenin was found to directly associate with the transcription factor Sox4. Association of syntenin with IL-5Ralpha was required for IL-5-mediated activation of Sox4. These studies identify a mechanism of transcriptional activation by cytokine-specific receptor subunits.

Animals↗

PubMed2001

Cytokine-induced inside-out activation of FcalphaR (CD89) is mediated by a single serine residue (S263) in the intracellular domain of the receptor.

Fc receptors play an important role in leukocyte activation and the modulation of ligand binding ("activation") is a critical point of regulation. Previous studies demonstrated that the Fc receptor for IgA (FcalphaRI/CD89) is regulated by cytokine stimulation, switching it to a high-binding state. To investigate the mechanism by which cytokine-induced signal transduction pathways result in FcalphaRI activation, cell lines expressing various receptor mutants were generated. Binding studies indicated that truncation of the C-terminus of the FcalphaRI resulted in constitutive IgA binding, removing the need for cytokine stimulation. Furthermore, mutagenesis of a single C-terminal serine residue (S263) to alanine (S>A) (single-letter amino acid codes) also resulted in constitutive IgA binding, whereas a serine to aspartate (S>D) mutation was no longer functional. The role of S263 might be in regulating the interaction with the cytoskeleton, because disruption of the cytoskeleton results in reduced IgA binding to both FcalphaRwt and FcalphaR_S>A. In addition, overexpression of a membrane-targeted intracellular domain of FcalphaR, and the introduction of cell-permeable CD89 fusion proteins blocked IgA binding, implying a competition for endogenous proteins. The proposal is made that Fc receptors are activated by cytokines via an inside-out mechanism converging at the cytoplasmic tail of these receptors. (Blood. 2001;97:3478-3483)

Antigens, CD↗

PubMed2001

IL-8 induces a transient arrest of rolling eosinophils on human endothelial cells.

Eosinophils exhibit a rolling interaction with E-selectin-expressing endothelium, and need to be activated by inflammatory mediators to firmly adhere to this surface. This study shows that IL-8 induces a transient arrest of unprimed eosinophils that roll on E-selectin present on TNF-alpha-activated HUVEC in an in vitro flow chamber. This process was antagonized by neutralizing Abs directed against IL-8 showing the specificity of the IL-8 effect. Furthermore, blocking Abs against both alpha(4) and beta(2) integrins inhibited the IL-8-induced transient arrest while these Abs had no effect when they were added separately. The IL-8-induced arrest was pertussis toxin sensitive. Studying the effect of IL-8 in more detail, we evaluated putative changes in intracellular Ca(2+) concentration in eosinophils induced by IL-8. We could show that IL-8 induces a transient rise in intracellular Ca(2+) concentration in approximately 40% of the cells provided that the eosinophils are interacting with endothelial cells or fibronectin-coated surfaces. Together these data show that resting eosinophils respond to IL-8 provided that the cells adhere on physiological surfaces. The induction of a transient arrest provides a new level of chemokine-induced regulation of leukocyte adhesion under flow conditions.

Calcium↗

PubMed2001

The clinical value of lung imaging fluorescence endoscopy for detecting synchronous lung cancer.

Some patients with non-small cell lung cancer (NSCLC) will also have a synchronous malignant lesion. The lung imaging fluorescence endoscopy (LIFE) has proven better than conventional white light bronchoscopy (WLB) for visualizing premalignant lesions or early stages of lung cancer. In this study, the additional value of LIFE in diagnosing synchronous lung cancers as well as the impact of these findings on definite therapy was analyzed. Seventy-two patients with recently diagnosed NSCLC or pulmonary lesions highly suspect of lung cancer were studied. Patients underwent WLB, followed by LIFE. Apart from the primary lesions, additional abnormal and suspicious lesions seen at WLB and LIFE were scored separately and biopsied. Sixty-nine patients had NSCLC and three patients had small cell lung carcinoma. Apart from the primary lesion, one up to six additional endobronchial lesions were visualized in 48 patients by WLB and/or LIFE. High-grade dysplastic lesions were detected in ten patients, three of whom were eligible for surgery of the primary tumor after completion of the investigations. Three other patients (4.3%) had synchronous cancers (NSCLC). In one patient, the lesion was visualized by LIFE and by WLB. The other two malignant lesions were detected only by LIFE. In these three latter patients, diagnostic work-up and definite treatment was changed, as a result of detection of synchronous lesions. In conclusion, LIFE has additional value in detecting synchronous malignant lesions in patients with primary lung cancer. The detection of these lesions changed diagnostic work-up and definite treatment plan. Therefore, LIFE should be used in the work-up of patients with primary lung cancer.

Adult↗

PubMed2001

Prophylactic cranial irradiation in limited disease small-cell lung cancer in complete remission: a retrospective analysis.

Recently a meta-analysis showed an improved survival probability of prophylactic cranial irradiation (PCI) in limited disease small-cell lung cancer (LD SCLC) in complete remission after chemotherapy. We evaluated treatment results of PCI+ and PCI- in these patients. Whether PCI (n = 65) or no PCI (n = 37) was administered did not depend either on patients or on tumour characteristics. After 2 years the incidence of brain metastases was 11% in PCI+ patients and 51% in PCI- patients. Both disease-free survival and overall survival were significantly longer after PCI. PCI reduces the incidence of brain metastases, prolongs brain metastases-free period, and overall survival in LD SCLC patients in complete remission after chemotherapy.

Brain Neoplasms↗

PubMed2000

Identification and characterization of CKLiK, a novel granulocyte Ca(++)/calmodulin-dependent kinase.

Human granulocytes are characterized by a variety of specific effector functions involved in host defense. Several widely expressed protein kinases have been implicated in the regulation of these effector functions. A polymerase chain reaction-based strategy was used to identify novel granulocyte-specific kinases. A novel protein kinase complementary DNA with an open reading frame of 357 amino acids was identified with homology to calcium-calmodulin-dependent kinase I (CaMKI). This has been termed CaMKI-like kinase (CKLiK). Analysis of CKLiK messenger RNA (mRNA) expression in hematopoietic cells demonstrated an almost exclusive expression in human polymorphonuclear leukocytes (PMN). Up-regulation of CKLiK mRNA occurs during neutrophilic differentiation of CD34(+) stem cells. CKLiK kinase activity was dependent on Ca(++) and calmodulin as analyzed by in vitro phosphorylation of cyclic adenosine monophosphate responsive element modulator (CREM). Furthermore, CKLiK- transfected cells treated with ionomycin demonstrated an induction of CRE- binding protein (CREB) transcriptional activity compared to control cells. Additionally, CaMK-kinasealpha enhanced CKLiK activity. In vivo activation of CKLiK was shown by addition of interleukin (IL)-8 to a myeloid cell line stably expressing CKLiK. Furthermore inducible activation of CKLiK was sufficient to induce extracellular signal-related kinase (ERK) mitogen-activated protein (MAP) kinase activity. These data identify a novel Ca(++)/calmodulin-dependent PMN- specific kinase that may play a role in Ca(++)-mediated regulation of human granulocyte functions.

Amino Acid Sequence↗

PubMed2000

Expression of the pro-apoptotic Bcl-2 family member Bim is regulated by the forkhead transcription factor FKHR-L1.

Cell death is regulated mainly through an evolutionarily conserved form of cell suicide termed apoptosis [1]. Deregulation of apoptosis has been associated with cancer, autoimmune diseases and degenerative disorders. Many cells, particularly those of the hematopoietic system, have a default program of cell death and survival that is dependent on the constant supply of survival signals. The Bcl-2 family, which has both pro- and anti-apoptotic members, plays a critical role in regulating cell survival [2]. One family member, the Bcl-2 interacting mediator of cell death (Bim), contains only a protein-interaction motif known as the BH3 domain, allowing it to bind pro-survival Bcl-2 molecules, neutralizing their function [3]. Disruption of the bim gene results in resistance to apoptosis following cytokine withdrawal in leukocytes, indicating that regulation of the pro-apoptotic activity of Bim is critical for maintenance of the default apoptotic program [4]. Here, we report that withdrawal of cytokine results in upregulation of Bim expression concomitant with induction of the apoptotic program in lymphocytes. Activation of the forkhead transcription factor FKHR-L1, previously implicated in regulation of apoptosis in T lymphocytes [5], was sufficient to induce Bim expression. We propose a mechanism by which cytokines promote lymphocyte survival by inhibition of FKHR-L1, preventing Bim expression.

Apoptosis↗

PubMed2000

A critical role for PI 3-kinase in cytokine-induced Fcalpha-receptor activation.

Fc-receptors, such as FcalphaR and FcgammaRII, play an important role in leukocyte activation, and rapid modulation of ligand binding ("activation") is critical for receptor regulation. We have previously demonstrated that ligand binding to Fc-receptors on human eosinophils is dependent on cytokine stimulation. Utilization of pharmacological inhibitors provided evidence that the phenomenon of interleukin (IL)-5 induced immunoglobulin A (IgA) binding to human eosinophils requires activation of phosphatidylinositol 3-kinase (PI3K). However, eosinophils are refractory to manipulation by molecular techniques such as DNA transfection or viral infection. Here we utilize an IL-3 dependent pre-B cell line to investigate the molecular mechanism of cytokine-mediated ligand binding to FcalphaR. In this system, IgA binding is dependent on IL-3, similarly to the requirement for IL-5 of eosinophils. We show that IL-3-mediated activation of FcalphaR (CD89) requires the activation of PI3K, independent of p21ras activation. Co-expression of dominant negative (triangle upp85) and active (p110_K227E) forms of PI3K demonstrate that the affinity switch regulating FcalphaR activation requires PI3K. Moreover, overexpression of PI3K is both necessary and sufficient for activation of FcalphaR. Furthermore, we show that IL-3/IL-5/GM-CSF induced inside-out signaling pathways activating FcalphaR require the involvement of protein kinase C downstream of PI3K. Finally, we show that these inside-out signaling pathways responsible for Fcalpha-receptor modulation require CD89, independent of its association with the FcRgamma chain. (Blood. 2000;95:2037-2043)

Animals↗

PubMed2000

STAT5-Dependent CyclinD1 and Bcl-xL expression in Bcr-Abl-transformed cells.

Signal transducers and activators of transcription (STATs) are a family of transcription factors that were originally identified as mediators of cytokine-induced gene expression. We and others have recently shown that STAT5 also plays a major role in cellular transformation by the Bcr-Abl oncogene. Here we show that the antiapoptotic bcl-xL gene product and the cell cycle regulator cyclin D1 are targets of STAT5 in Bcr-Abl-transformed cells. In the CML cell line K562 and in BaF3 cells ectopically expressing Bcr-Abl, both the cyclin D1 and bcl-x promoters are highly active. The activity of these promoters can be strongly repressed by cotransfection of a dominant negative (DN) mutant of STAT5. Moreover, the cyclin D1 and bcl-x promoters contain STAT binding sites to which STAT5 constitutively binds in Bcr-Abl transformed cells. These results suggest that STAT5 contributes to transformation by Bcr-Abl by induction of cyclin D1 and bcl-xL expression.

Apoptosis↗

PubMed2000

Identification of cytokine-regulated genes in human leukocytes in vivo.

BACKGROUND: Human polymorphic nuclear granulocytes (PMNs) such as neutrophils and eosinophils play a critical role in mediating inflammatory responses to microbial and parasitic infections. Exposure of these leukocytes to cytokines leads to an amplification of granulocyte effector functions by a mechanism termed "priming." Although many studies have investigated the effects of granulocyte priming, little is known concerning the molecular mechanisms that lead to this phenomenon. OBJECTIVE: The purpose of this study was to identify potential markers for granulocyte priming and thus also to gain further insight into the pathogenesis of inflammatory responses. METHODS: We used a modified differential display technique, random arbitrary primed-PCR to identify genes regulated during the priming of human polymorphic nuclear granulocytes by GM-CSF in vitro. Genes identified were validated by Northern blot analysis of in vitro and in vivo primed leukocytes. RESULTS: Several genes were identified and their expression characterized in vitro. One of these genes, 5-lipoxygenase-activating protein, was also found to be up-regulated in leukocytes isolated after allergen challenge of allergic asthmatic patients. CONCLUSION: The use of differential display technology is a rapid and effective means of identifying genes whose expression is regulated by priming in vitro and in vivo. Further analysis will lead to a better understanding of the priming phenotype and may provide further insight into the pathologic mechanisms of inflammatory processes.

5-Lipoxygenase-Activating Proteins↗

PubMed2000

Forkhead transcription factor FKHR-L1 modulates cytokine-dependent transcriptional regulation of p27(KIP1).

Interleukin-3 (IL-3), IL-5, and granulocyte-macrophage colony-stimulating factor regulate the survival, proliferation, and differentiation of hematopoietic lineages. Phosphatidylinositol 3-kinase (PI3K) has been implicated in the regulation of these processes. Here we investigate the molecular mechanism by which PI3K regulates cytokine-mediated proliferation and survival in the murine pre-B-cell line Ba/F3. IL-3 was found to repress the expression of the cyclin-dependent kinase inhibitor p27(KIP1) through activation of PI3K, and this occurs at the level of transcription. This transcriptional regulation occurs through modulation of the forkhead transcription factor FKHR-L1, and IL-3 inhibited FKHR-L1 activity in a PI3K-dependent manner. We have generated Ba/F3 cell lines expressing a tamoxifen-inducible active FKHR-L1 mutant [FKHR-L1(A3):ER*]. Tamoxifen-mediated activation of FKHR-L1(A3):ER* resulted in a striking increase in p27(KIP1) promoter activity and mRNA and protein levels as well as induction of the apoptotic program. The level of p27(KIP1) appears to be critical in the regulation of cell survival since mere ectopic expression of p27(KIP1) was sufficient to induce Ba/F3 apoptosis. Moreover, cell survival was increased in cytokine-starved bone marrow-derived stem cells from p27(KIP1) null-mutant mice compared to that in cells from wild-type mice. Taken together, these observations indicate that inhibition of p27(KIP1) transcription through PI3K-induced FKHR-L1 phosphorylation provides a novel mechanism of regulating cytokine-mediated survival and proliferation.

Animals↗

PubMed2000

Monitoring of neutrophil priming in whole blood by antibodies isolated from a synthetic phage antibody library.

Neutrophil activation is a multistep process. In vitro activation of neutrophils with semiphysiological activators is optimal only after preactivation or priming with cytokines, chemotaxins, and/or bacterial products. Until now, no antibodies have been developed that can distinguish between resting and (cytokine) primed neutrophils with a sufficient dynamic range necessary for screening clinical samples. We have isolated two human phage antibodies, designated MoPhab A17 and A27, from a synthetic bacteriophage antibody library. These phage antibodies recognize epitopes that are upregulated on neutrophils present in whole blood treated with low priming concentrations of cytokines, such as GM-CSF and TNF-alpha. This induction was time- and concentration-dependent and optimal at concentrations that are sufficient for priming functional responses in neutrophils: GM-CSF (10 pM) and TNF-alpha (100 IU/ml). PMNs, isolated from the peripheral blood of chronic obstructive pulmonary disease (COPD) patients with a clinical exacerbation, exhibited a partial in vivo primed phenotype. These antibodies promise to be an ideal tool to monitor disease activity in whole blood of patients with inflammatory diseases.

Adult↗

PubMed2000

In vivo priming of FcalphaR functioning on eosinophils of allergic asthmatics.

Inflammation in allergic asthma is characterized by an influx of eosinophils and the presence of eosinophil products in the bronchial tissue. Orchestration of this inflammatory response is in part mediated by cytokines and chemoattractants, but final activation can require additional stimuli. IgA, the most abundant immunoglobulin at mucosal surfaces, is potentially a potent trigger for eosinophil activation. Previously, we have shown that binding IgA-coated targets is dependent on in vitro stimulation of cells with cytokines. Here, we demonstrate that eosinophils isolated from the blood of allergic asthmatic patients bind IgA beads independently of prior in vitro stimulation. Furthermore, we found that the proinflammatory cytokine, TNF-alpha, is a potent enhancer of IgA binding to eosinophils from allergic asthmatics, and it does not activate FcalphaR on eosinophils isolated from normal donors. The difference in IgA binding by FcalphaRs on normal and patient eosinophils might be explained by the activation of different signal transduction pathways. Studying intracellular signaling, we found an enhanced basal activity of phosphatidylinositol 3-kinase (PI3K) in eosinophils derived from allergic asthmatics. Moreover, inhibition of PI3K in these cells blocked the background and the TNF-alpha-induced IgA binding completely. In summary, these data demonstrate that the responsiveness of human eosinophils to TNF-alpha might be an important contribution for fine-tuning the allergic inflammatory reaction. Furthermore, the preactivation of PI3K results in a broader sensitivity to subsequent challenge with inflammatory cytokines.

Adolescent↗

PubMed1999

Association of RACK1 and PKCbeta with the common beta-chain of the IL-5/IL-3/GM-CSF receptor.

Granulocyte macrophage colony stimulating factor (GM-CSF), interleukin-3 (IL-3) and interleukin-5 (IL-5 belong to a family of cytokines that regulate proliferation, differentiation and function of haematopoietic cells. Their receptor consists of a ligand specific alpha-chain and a signal transducing beta-chain (betac). While, the role of phosphotyrosine residues in the betac as mediators of downstream signalling cascades has been established, little is known about non-phosphotyrosine mediated events. To identify proteins interacting with betac, we screened a yeast two-hybrid library with the intracellular domain of betac. We found that RACK1, a molecule associating with activated PKC, PLCgamma and Src kinases, associated with the membrane proximal region of betac in both yeast two-hybrid, immunoprecipitation and GST-pull-down assays. The association of RACK1 was constitutive, demonstrating no alteration upon cellular stimulation. Furthermore, upon stimulation of cells with IL-5 or PMA, a complex of betac and PKCbeta was found. Together, these findings suggest a novel role for RACK1 as a possible adapter molecule associating with the intracellular domain of cytokine receptors.

Animals↗

PubMed1999

A composite C/EBP binding site is essential for the activity of the promoter of the IL-3/IL-5/granulocyte-macrophage colony-stimulating factor receptor beta c gene.

The common beta-chain (beta c) is the main signaling component of the heterodimeric receptors for IL-3, IL-5, and GM-CSF and is primarily expressed on myeloid cells. The proximal beta c promoter is regulated by GGAA binding proteins, including PU.1, a hemopoietic specific member of the Ets family. However, it is not likely that PU.1 alone accounts for the myeloid-restricted expression of the beta c subunit. Here we describe the identification of a C/EBP binding enhancer that is located 2 kb upstream of the transcription start site. The enhancer contains two elements that bind C/EBP alpha and -beta in U937 cells, while C/EBP epsilon is also bound in extracts of HL-60 cells. Importantly, deletion of the enhancer or mutation of either of one of the C/EBP sites results in a complete loss of promoter activity in cell lines as well as in primary cells, showing the importance of C/EBP members in beta c gene activation. We further show that PU.1 has to cooperate with C/EBP proteins to induce beta c transcription. Since the beta c is already expressed on CD34+ cells, these results demonstrate that both C/EBP and PU.1 are not only important for the myeloid-specific gene regulation at later stages of myeloid differentiation.

Animals↗

PubMed1999

STAT5 activation by BCR-Abl contributes to transformation of K562 leukemia cells.

Signal transducers and activators of transcription (STATs) belong to a family of transcription factors that were originally identified as mediators of cytokine-induced gene expression. Recent evidence, however, has shown that certain members of the STAT family, including STAT3, are also involved in cellular transformation. Here we show that STAT5 also plays a role in cellular transformation by the BCR-Abl oncogene. In BCR-Abl transformed K562 cells, STAT5A and 5B are constitutively phosphorylated on tyrosine and are transcriptionally active. Moreover, expression of a dominant negative form of STAT5 shows that active STAT5 is necessary for the growth in soft agar of these cells. These results show that besides STAT3, STAT5 can also be involved in cellular transformation.

Cell Transformation, Neoplastic↗

PubMed1999

Regulation of p21rac activation in human neutrophils.

The small guanosine triphosphate (GTPase) p21rac is highly expressed in human neutrophils where it is thought to play a role in cytoskeletal reorganization and superoxide production. Using the p21rac binding domain of PAK (PAK-RBD) as an activation-specific probe, we have investigated agonist-stimulated activation of p21rac. Stimulation of neutrophils with the chemoattractants fMet-Leu-Phe (fMLP) or platelet-activating factor (PAF) induced an extremely rapid and transient p21rac activation, being optimal within 5 seconds. This activation correlates with the rapid changes of intracellular free Ca(2+) ([Ca(2+)](i)) stimulated by fMLP; however, changes in [Ca(2+)](i) were neither sufficient nor required for p21rac activation. Furthermore, fMLP-induced p21rac activation was not inhibited by broad tyrosine kinase inhibitors or specific inhibitors of ERK, p38 mitogen activated protein kinase, Src, or phosphatidylinositol 3-kinases. Surprisingly, the cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha did not cause p21rac activation or modulate fMLP-induced p21rac activation. AlF(-), a potent activator of heterotrimeric G-protein alpha-subunits, however, was found to activate p21rac. Stimulation of neutrophils with phorbol myristate acetate (PMA) strongly activated the respiratory burst, but did not induce p21rac activation, suggesting that superoxide production per se can occur independently of p21rac activation. These data suggest that in human granulocytes, G-protein coupled receptors, but not cytokine receptors, activate p21rac via a rapid, novel exchange-mechanism independently of changes in [Ca(2+)](i), tyrosine phosphorylation, or PI3K.

Calcium↗