Biomedical subjects

B Johansen

Publications and source records attributed to B Johansen.

At least 19 recordsLinked to original sources

PubMed2004

Enzymatically modified low-density lipoprotein upregulates CD36 in low-differentiated monocytic cells in a peroxisome proliferator-activated receptor-gamma-dependent way.

Peroxisome proliferator-activated receptor-gamma (PPARgamma) has been suggested to upregulate CD36. Since free oxidized polyunsaturated fatty acids are PPARgamma ligands, we studied the effects of LDL modified by the simultaneous action of sPLA2 and 15-lipoxygenase (15LO) on CD36 expression and PPARgamma activation in monocytic cells. Exposure of MM6 cells, which do not express CD36 or other scavenger receptors, to such enzymatically modified LDL (enzLDL) resulted in upregulation of CD36 surface protein and mRNA expression. Similar effects were observed with free 13-hydroperoxyoctadecadienoic acid but not its esterified counterpart. Less pronounced effects were observed with LDL modified by 15LO alone. Upregulation of CD36 was inversely correlated to the state of cell differentiation, as showed by lower response to enzLDL of the scavenger receptor-expressing MM6-sr and THP1 cells. Importantly, LDL modified by sPLA2 and 15LO did not efficiently induce upregulation CD36 in PPARgamma-deficient macrophage-differentiated embryonic stem cells confirming a role of PPARgamma in CD36 expression in cells stimulated with enzLDL. Our data show that LDL modified with physiologically relevant enzymes stimulates CD36 expression in non-differentiated monocytes and that this process involves PPARgamma activation. These effects of enzLDL can be considered pro-atherogenic in the context of early atherosclerosis.

Arachidonate 15-Lipoxygenase↗

PubMed2004

Trends in symptoms of obstructive lung disease in Norway.

SETTING: Evidence is accumulating that there has been an increase in the adult population burden of obstructive lung disease. Has this increased the burden of symptoms? It is possible that diagnostic efficiency has improved, so that milder asthma cases are being diagnosed. OBJECTIVE: To investigate changes in symptom burden by asthma diagnosis, age and sex. DESIGN: We performed two postal cross-sectional studies among adults aged 15-70 years in Oslo, Norway, in 1972 and again in 1998/1999 (total = 39998). Changes in 11 self-reported respiratory symptoms were investigated. RESULTS: The prevalence of having at least one symptom increased from 50% to 60% (P < 0.001), and the distribution of symptoms showed an overall increase. Nine symptoms increased in prevalence. The increase was largest among the young and females, and was present in both those with and those without asthma. For any given number of reported symptoms, asthma prevalence was higher in 1998 than in 1972, suggesting increased case finding. CONCLUSION: There has been an increase in the population burden of respiratory symptoms matching the observed increase in young adult asthma, together with a probable increase in the clinical willingness to give an asthma diagnosis.

Adolescent↗

PubMed2003

Long-term changes in adult asthma prevalence.

There has been an increase in asthma prevalence among children. Little evidence is available regarding long-term changes in asthma prevalence in adults. Two cross-sectional studies were performed among adults aged 15-70 yrs in Oslo, Norway, in 1972 and again in 1998-1999 (n=39,998). A postal self-completed questionnaire was used. Exactly the same questions and survey methods were used in both studies. In 1998-1999, additional telephone follow-up was included for postal nonresponders. The crude prevalence of ever having had a doctor's diagnosis of asthma increased from 3.4 to 9.3%. The prevalence of wheezing increased from 17.8 to 25.8% and attacks of breathlessness from 12.6 to 16.7%. After controlling for smoking, the risk of asthma among those aged <40 yrs had tripled. The increase in asthma was 50% greater in females than males. The prevalence of symptoms increased less than asthma diagnosis. Wheezing increased by 50% in those aged <40 yrs, with smaller increases at greater ages. The increase in symptoms was seen among both asthmatics and nonasthmatics. There has been a large increase in the prevalence of asthma diagnosis and asthma-like symptoms in adults. The increase is less pronounced among those aged >40 yrs.

Adolescent↗

PubMed2001

[General practitioners' knowledge of and attitude to assessment and treatment of women with urinary incontinence. A questionnaire among general practitioners in Denmark].

INTRODUCTION: Urinary incontinence is a common problem for adult women, and the need for assessment and treatment of incontinence is expected to increase in the future. The aim of this study was to elucidate the general practitioners' (GPs) knowledge about and attitude to women with urinary incontinence. METHODS: A questionnaire was posted to 1700 randomly selected GPs in 1998 and 1999. RESULTS: A total of 1071 (63%) GPs responded at least once. Five hundred (29%) returned the questionnaire both years. About 50% expressed a positive interest in the management of urinary incontinence. Only 24% felt that their knowledge was sufficient to manage incontinence. About 50% and 66% of the GPs would probably refer a patient with stress incontinence or urge incontinence to a specialist. The GPs' proposals for assessment and treatment were mainly consistent with good clinical practice. There were only minor changes in knowledge and attitude from 1998 to 1999. DISCUSSION: GPs' interest in urinary incontinence is moderate and management is characterised by a high referral rate to a specialist. Most GPs. consider their knowledge to be inadequate. There is need for education to ensure sufficient knowledge and to change the attitude, so that first-line assessment and treatment of urinary incontinence is carried out in general practice.

Adult↗

PubMed2001

Atypical lambda/iota PKC conveys 5-lipoxygenase/leukotriene B4-mediated cross-talk between phospholipase A2s regulating NF-kappa B activation in response to tumor necrosis factor-alpha and interleukin-1beta.

The transcription factor nuclear factor kappaB (NF-kappaB) plays crucial roles in a wide variety of biological functions such as inflammation, stress, and immune responses. We have shown previously that secretory nonpancreatic (snp) and cytosolic (c) phospholipase A(2) (PLA(2)) regulate NF-kappaB activation in response to tumor necrosis factor (TNF)-alpha or interleukin (IL)-1beta activation and that a functional coupling mediated by the 5-lipoxygenase (5-LO) metabolite leukotriene B(4) (LTB(4)) exists between snpPLA(2) and cPLA(2) in human keratinocytes. In this study, we have further investigated the mechanisms of PLA(2)-modulated NF-kappaB activation with respect to specific kinases involved in TNF-alpha/IL-1beta-stimulated cPLA(2) phosphorylation and NF-kappaB activation. The protein kinase C (PKC) inhibitors RO 31-8220, Gö 6976, and a pseudosubstrate peptide inhibitor of atypical PKCs attenuated arachidonic acid release, cPLA(2) phosphorylation, and NF-kappaB activation induced by TNF-alpha or IL-1beta, thus indicating atypical PKCs in cPLA(2) regulation and transcription factor activation. Transfection of a kinase-inactive mutant of lambda/iotaPKC in NIH-3T3 fibroblasts completely abolished TNF-alpha/IL-1beta-stimulated cellular arachidonic acid release and cPLA(2) activation assayed in vitro, confirming the role of lambda/iotaPKC in cPLA(2) regulation. Furthermore, lambda/iotaPKC and cPLA(2) phosphorylation was attenuated by phosphatidyinositol 3-kinase (PI3-kinase) inhibitors, which also reduced NF-kappaB activation in response to TNF-alpha and IL-1beta, indicating a role for PI3-kinase in these processes in human keratinocytes. TNF-alpha- and IL-1beta-induced phosphorylation of lambda/iotaPKC was attenuated by inhibitors toward snpPLA(2) and 5-LO and by an LTB(4) receptor antagonist, suggesting lambda/iotaPKC as a downstream effector of snpPLA(2) and 5-LO/LTB(4) the LTB(4) receptor. Hence, lambda/iotaPKC regulates snpPLA(2)/LTB(4)-mediated cPLA(2) activation, cellular arachidonic acid release, and NF-kappaB activation induced by TNF-alpha and IL-1beta. In addition, our results demonstrate that PI3-kinase and lambda/iotaPKC are involved in cytokine-induced cPLA(2) and NF-kappaB activation, thus identifying lambda/iotaPKC as a novel regulator of cPLA(2).

3T3 Cells↗

PubMed2001

[Vaginal hysterectomy in non-prolapsed uterus].

INTRODUCTION: There is an increasing number of methods available for removing the uterus, but no multicentre, randomised, clinical trials are available to show which type of operation ensures the best outcome for the patient. The charts of 207 vaginal hysterectomies were reviewed in this descriptive study. The aim was to examine whether vaginal hysterectomy might be an alternative for a group of patients. MATERIAL AND METHODS: Only patients with a previous, vaginal birth were entered in the study (four patients had not given birth). A uterus weight of 500-600 g was the upper limit set by our group for the use of the vaginal route. Patient characteristics, data from the operations, complications, and histological examinations of the uterus were analysed. RESULTS: The mean operation time was 61 min (95% CI 58-64 min), range 25-115 min. The difference between preoperative and postoperative haemoglobin was 1.1 mmol/l (95% CI 1.0-1.2 mmol/l). The mean length of hospital stay was 2.9 days (95% CI 2.7-3.1 days). The complications were 1) febrile morbidity; 17 (8%) (95% CI 4-12%); 2) urinary tract injury, 3 (2%) (95% CI 0-3%); 3) unforeseen need for major surgery (including conversion to abdominal hysterectomy), 3 (2%) (95% CI 0-3%). DISCUSSION: In some patients, vaginal hysterectomy is a good alternative.

Adult↗

PubMed2001

Functional coupling between secretory and cytosolic phospholipase A2 modulates tumor necrosis factor-alpha- and interleukin-1beta-induced NF-kappa B activation.

Tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta are potent activators of the transcription factor NF-kappaB, induced during inflammatory conditions. We have previously shown that both secretory and cytosolic phospholipase A(2) (PLA(2)) are involved in TNF-alpha- and IL-1beta-induced NF-kappaB activation. In this study, we have addressed the mechanism of PLA(2) involvement with respect to downstream arachidonic acid (AA) metabolites and the functional coupling between PLA(2)s mediating NF-kappaB activation. We show that in addition to inhibitors of secretory and cytosolic PLA(2)s, 5-lipoxygenase inhibitors attenuate TNF-alpha- and IL-1beta-stimulated NF-kappaB activation. Exogenous addition of leukotriene B(4) (LTB(4)) restored NF-kappaB activation reduced by 5-lipoxygenase inhibitors or an LTB(4) receptor antagonist, thus identifying LTB(4) as a mediator in signaling to NF-kappaB. TNF-alpha- and IL-1beta-induced AA release from cellular membranes was accompanied by phosphorylation of cytosolic PLA(2). Inhibitors of secretory PLA(2) and of 5-lipoxygenase/LTB(4) functionality markedly reduced AA release and nearly completely abolished cytosolic PLA(2) phosphorylation. This demonstrates that secretory PLA(2), through 5-lipoxygenase metabolites, is an essential upstream regulator of cytosolic PLA(2) and AA release. Our results therefore suggest the existence of a functional link between secretory and cytosolic PLA(2) in cytokine-activated keratinocytes, providing a molecular explanation for the participation of both secretory and cytosolic PLA(2) in arachidonic acid signaling and NF-kappaB activation in response to proinflammatory cytokines.

Animals↗

PubMed2001

Expression of a membrane-anchored endo-1,4-beta-glucanase from Brassica napus, orthologous to KOR from Arabidopsis thaliana, is inversely correlated to elongation in light-grown plants.

A PCR fragment derived from a membrane-anchored endo-1,4-beta-glucanase cDNA was amplified using degenerated oligonucleotides and mRNA from oilseed rape (Brassica napus L.) siliques. Sequence analysis of the corresponding gene, Cel16, showed that the predicted Cel16 protein has high identity with the Arabidopsis KOR protein (94%). High-stringency genomic Southern analysis further revealed that Cel16 and KOR are most likely orthologous genes performing a similar function in both species. Northern blot and GUS analysis of transgenic Arabidopsis containing a fusion between a 2.0 kb Cel16 promoter fragment and the GUS reporter gene showed that Cel16 was expressed at a low level in the primary raceme, the young lateral stems, the elongation zone of the primary root and the older root base. By contrast, a high level of Cel16 mRNA accumulation was found in the young root and in the main stem carrying flowers and young siliques. Cel16 transcripts were localized to the apical meristem, cambium, primary xylem and cortex of oilseed rape stem tissue by in situ RT-PCR. A similar pattern of activity was found in the GUS analysis of transgenic Arabidopsis. Cel16 mRNA accumulation in the main stem was lower in the zone of most rapid cell elongation than in the subjacent, fully elongated internodes. Similarly, Cel16 transcripts accumulated to a higher level in leaves as they reached full size than during early leaf expansion. Analysis of the expression pattern in elongating, light-grown seedlings showed that Cel16 mRNA accumulated at a lower level in the elongating upper third than elsewhere in the hypocotyl. This is contrary to etiolated hypocotyls, where we found a higher expression level in the rapidly elongating upper part. This difference in expression most probably reflects a difference in cell wall assembly between light- and dark-grown seedlings.

Arabidopsis↗

PubMed2001

Simian virus 40 large T-antigen, but not small T-antigen, trans-activates the human cytomegalovirus major immediate early promoter.

Cytomegalovirus infection is a major cause of morbidity in immunocompromised patients. The major immediate early promoter/enhancer (MIEP) of the human cytomegalovirus controls the expression of the immediate early genes 1 and 2 which play a central role both in primary and reactivated human cytomegalovirus (HCMV)-infections. Our previous studies have shown that co-infection of A549 cells with human cytomegalovirus and human polyomavirus BK resulted in enhanced expression of the immediate early genes 1 and 2 and that the early gene products of BK virus trans-activated the MIEP. However, neither the MIEP sequences required for mediating this trans-activation, nor the contribution of the individual BK virus early gene products were examined. The MIEP contains multiple binding sites for the transcription factors CREB, AP1, Sp1 and NFkappaB, which may mediate polyomavirus large T- or small t-antigens-induced promoter activation. Transient transfection studies in A549 cells demonstrated that SV40 large T-antigen, but not small t-antigen, trans-activated MIEP activity approximately 9-fold. Mutations in individual binding motifs in the context of the complete MIEP did not impair traits-activation by large T-antigen. The level of induction of a truncated MIEP consisting of a single set of CRE/AP1, NFkappaB, and Sp1 binding motifs by large T-antigen was reduced 2-fold compared to the full length MIEP. Extended truncations diminished trans-activation by large T-antigen. To determine the contribution of a single binding motif in the trans-activation by large T-antigen, a CRE/AP1, an NFkappaB, an Sp1, or a non-consensus Sp1-motif, respectively, was linked to the MIEP TATA-sequence respecting the natural spacing between the two transcription regulatory elements. Only the MIEP TATA-box with the correctly spaced non-consensus Sp1 binding site (GT-motif) was stimulated by large T-antigen. These results suggest that an isolated non-consensus Sp1-motif is important for trans-activation of the MIEP by large T-antigen, but that other cis-acting elements can compensate for this element in the context of the whole MIEP.

Antigens, Polyomavirus Transforming↗

PubMed2000

Arabidopsis map kinase 4 negatively regulates systemic acquired resistance.

Transposon inactivation of Arabidopsis MAP kinase 4 produced the mpk4 mutant exhibiting constitutive systemic acquired resistance (SAR) including elevated salicylic acid (SA) levels, increased resistance to virulent pathogens, and constitutive pathogenesis-related gene expression shown by Northern and microarray hybridizations. MPK4 kinase activity is required to repress SAR, as an inactive MPK4 form failed to complement mpk4. Analysis of mpk4 expressing the SA hydroxylase NahG and of mpk4/npr1 double mutants indicated that SAR expression in mpk4 is dependent upon elevated SA levels but is independent of NPR1. PDF1.2 and THI2.1 gene induction by jasmonate was blocked in mpk4 expressing NahG, suggesting that MPK4 is required for jasmonic acid-responsive gene expression.

Alleles↗

PubMed2000

Ceramide binds to the CaLB domain of cytosolic phospholipase A2 and facilitates its membrane docking and arachidonic acid release.

Excessive production of eicosanoids is characteristic of many inflammatory diseases. In this study we show that ceramide, which is an early messenger of inflammatory cytokine action, exerts a dual effect on the cytosolic phospholipase A2 (cPLA2), the rate-limiting enzyme in arachidonic acid release and subsequent eicosanoid formation. Stimulation of renal mesangial cells with exogenous short-chain ceramide analogs for 30 and 60 min leads to a concentration-dependent increase in arachidonic acid release that is not blocked by specific inhibitors of mitogen-activated protein kinase pathways. This suggests that these established upstream activators of cPLA2 are not involved in ceramide-induced arachidonic acid release. By use of photoactivatable ceramide analogs, D- and L-[125I]3-trifluoromethyl-3-(m-iodophenyl)diazirine-ceramides (TID-ceramides), we observed a direct interaction of ceramide with cPLA2. This interaction was independent of the absolute configuration as D- and L-TID-ceramide were equally effective in binding to cPLA2. Moreover, recombinant CaLB domain of cPLA2 as well as a mutant deficient in the connecting 'hinge' domain of cPLA2, efficiently bound D- and L-TID-ceramides, whereas the catalytic domain did not interact with TID-ceramides. In vitro binding assays reveal that stearoyl-arachidonyl-phosphatidylcholine (SAPC)-liposomes containing increasing mol% of ceramide lead to an increased association of recombinant cPLA2 to the liposomes. Furthermore, measurement of cPLA2 activity in vitro shows that the presence of SAPC-liposomes resulted in only weak cPLA2 activity. However, the activity dramatically increases by addition of ceramide to the liposomes. Furthermore, liposomes containing SAPC and sphingomyelin resulted in no better substrate than SAPC liposomes, unless bacterial sphingomyelinase was added to generate ceramide, which then causes a marked increase in cPLA2 activity. These results demonstrate that ceramide can interact directly with cPLA2 via the CaLB domain and thereby serves as a membrane-docking device that facilitates cPLA2 action in inflammatory diseases.

Animals↗

PubMed2000

Molecular basis for the association of group IIA phospholipase A(2) and decorin in human atherosclerotic lesions.

Group IIA secretory nonpancreatic phospholipase A(2) (snpPLA(2)) is associated with collagen fibers in the extracellular matrix of human atherosclerotic plaques. Decorin, a small proteoglycan (PG) carrying chondroitin/dermatan sulfate glycosaminoglycans (GAGs), forms part of the collagen network in human arteries. To explore whether snpPLA(2) may be associated with collagen fibers via interaction with decorin, we performed (1) immunohistochemistry to compare the relative in vivo localization of snpPLA(2) and decorin in human atherosclerotic tissue and (2) in vitro experiments to study the interaction between snpPLA(2) and decorin. In atherosclerotic lesions, decorin was detected within the snpPLA(2)-positive part of the intima close to the media. Electrophoretic mobility shift assay showed that snpPLA(2) binds to decorin synthesized by human fibroblasts. Native and GAG-depleted decorin enhanced the association of snpPLA(2) to collagen types I and VI in a solid-phase binding assay. Furthermore, snpPLA(2) bound efficiently to a recombinant decorin core protein fragment B/E (Asp45-Lys359). This binding was competed with soluble decorin and inhibited at NaCl concentrations >150 mmol/L. The decorin core protein fragment B/E competed better than dermatan sulfate for binding of snpPLA(2) to decorin-coated microtiter wells. The enzymatic activity of snpPLA(2) increased 2- to 3-fold in the presence of decorin or GAG-depleted decorin. The results show that snpPLA(2) binds preferentially to the decorin protein core rather than to the GAG chain and that this interaction enhances snpPLA(2) activity. As a consequence, this active extracellular enzyme may contribute to the pathogenesis of atherosclerosis by modifying lipoproteins and releasing inflammatory lipid mediators at places of lipoprotein retention in the arterial wall.

Arteriosclerosis↗

PubMed2000

Secretory and cytosolic phospholipase A(2)regulate the long-term cytokine-induced eicosanoid production in human keratinocytes.

The involvement of cytosolic phospholipase A(2)(cPLA(2)) and secretory non-pancreatic PLA(2)(npPLA(2)) in release of arachidonic acid (AA) preceding eicosanoid formation in the human keratinocyte cell line HaCaT was examined. Interleukin 1beta (IL-1beta) and tumour necrosis factor-alpha (TNF), phorbol myristate acetate (PMA) and calcium ionophore A(23187)increased the extracellular AA release, and stimulated eicosanoid synthesis as determined by HPLC analysis. The main metabolites after stimulation with IL-1beta, PMA or A(23187)were PGE(2), an unidentified PG and LTB(4), while TNF stimulated HETE-production. Both cPLA(2)and npPLA(2)message and enzyme activity were detected in unstimulated HaCaT cells. IL-1beta, PMA and TNF increased both cPLA(2)enzyme activity and expression, but did not lead to any increase in npPLA(2)expression or activity. The selective npPLA(2)inhibitors LY311727 and 12-epi-scalaradial, or the cPLA(2)inhibitor arachidonyl trifluoro methyl ketone (AACOCF(3)) reduced IL-1beta-induced eicosanoid production in a concentration dependent manner. The results presented strongly suggest that both cPLA(2)and npPLA(2)contribute to the long-term generation of AA preceding eicosanoid production in differentiated, human keratinocytes. Inhibitors against npPLA2 or cPLA2 enzymes should be useful in treating inflammatory skin diseases, such as psoriasis.

Arachidonic Acid↗

PubMed2000

Molecular genetic analysis of severe protein C deficiency.

Severe protein C deficiency is a rare, early onset, venous thrombotic condition that is inherited as an autosomal recessive trait. The protein C (PROC) genes of nine unrelated individuals with severe protein C deficiency were sequenced yielding a total of 13 different lesions. Eight of these were novel, including a gross gene deletion, three missense mutations, two micro-deletions, a splicing mutation and a single base-pair substitution in the HNF-3 binding site in the PROC gene promoter. Evidence for the pathogenicity of the mutations detected was obtained by molecular modelling, in vitro splicing assay and reporter gene assay. Neither the plasma protein C activity level nor the nature of the PROC gene lesions detected were found to be a good prognostic indicator of the age of onset or clinical severity of thrombotic symptoms. Other factors may thus complicate the relationship between genotype and clinical phenotype. Indeed, in two patients, the inheritance of either one or two Factor V Leiden alleles in addition to two PROC gene lesions could have served to precipitate the thrombotic events. No association was however apparent between clinical severity and the possession of a particular promoter polymorphism genotype. Despite the absence of a clear genotype-phenotype relationship, the molecular genetic analysis of the severe recessive form of protein C deficiency potentiates both the counselling of affected families and the provision of antenatal exclusion diagnosis.

Alternative Splicing↗

PubMed2000

Expression of cytosolic and secreted forms of phospholipase A(2) and cyclooxygenases in human placenta, fetal membranes, and chorionic cell lines.

Lipid mediators play a crucial role in human parturition and phospholipase A(2) (PLA(2)) is a key regulator of the production of these compounds. We have investigated by PCR the expression of different groups of PLA(2) and COX enzymes in human fetal membranes (amnion and chorion), placenta and three chorionic cell lines (JEG-3, Jar, BeWo). Our data show that the cytosolic Group IV PLA(2) and COX-1 are expressed in all of them, whereas the secretory forms of PLA(2), (Groups IIA, and V), have a more restricted expression. Group IIA mRNA is most abundant in placenta and chorion, whereas Group V PLA(2) mRNA is most abundant in placenta and amnion. On the other hand, COX-2 is present in placenta, chorion and amnion, but was not detected in any of the chorionic cell lines. These results suggest that both cytosolic and distinct secreted forms of PLA(2) could be involved in arachidonic acid (AA) release preceding prostaglandin production at the fetal/maternal interface.

Choriocarcinoma↗

PubMed2000

Mildly oxidized LDL induces expression of group IIa secretory phospholipase A(2) in human monocyte-derived macrophages.

Phospholipase A(2)s (PLA(2)s) constitute a family of enzymes that hydrolyze fatty acids of membrane phospholipids, thus initiating the synthesis of proinflammatory mediators. Various PLA(2)s have been detected in human atherosclerotic arteries (advanced lesions); however, only the secretory group of PLA(2) has been shown to specifically hydrolyze low density lipoprotein (LDL)-associated phospholipids and, as such, may play a potential role in atherogenesis. In the present study, we investigated the expression pattern of group IIa, IV, and V PLA(2)s in human macrophages, which are the key cells involved in the onset and perpetuation of atherosclerosis. Immunohistochemical staining by double labeling showed that the secretory nonpancreatic PLA(2) (snpPLA(2)) is detectable in macrophages in the intima of early atherosclerotic lesions. Reverse transcription-polymerase chain reaction analysis of RNA extracted from human monocytes clearly showed that expression of group IV PLA(2) was enhanced during differentiation into macrophages, with an onset of induction at days 2 to 3 of differentiation. Group V snpPLA(2) was constitutively expressed on differentiation, whereas the detection of group IIa snpPLA(2) was dependent on both differentiation and subsequent stimulation of macrophages. Indeed, the transcription of group IIa snpPLA(2) in macrophages was induced by treatment with minimally modified or mildly oxidized LDL, whereas native, extensively oxidized, or acetylated LDL had no effect. To our knowledge, this is the first report describing induction of group IIa snpPLA(2) expression in human monocyte-derived macrophages. The mRNA levels of cytosolic PLA(2) group IV and snpPLA(2) group V remained unchanged on LDL treatment. Thus, our results show that the expression of distinct PLA(2) enzymes is regulated not only during differentiation of monocytes into macrophages but also on exposure of macrophages to distinct LDL species. Consequently, our results indicate a potential role for both cytosolic and secretory PLA(2) enzymes in inflammation and in macrophage functions related to atherosclerosis, with a specific role for group IIa snpPLA2 in LDL scavenging.

Arteriosclerosis↗

PubMed2000

Presence of group IIa secretory phospholipase A2 in mast cells and macrophages in normal human ileal submucosa and in Crohn's disease.

Secretory group IIa phospholipase A2 (PLA2-II) is an important regulator of proinflammatory lipid mediator production and may play a role in ileal inflammation in Crohn's disease. The enzyme has previously only been detected in epithelial Paneth cells. However, one characteristic feature of Crohn's disease is the transmural inflammation. Full thickness ileal sections from nine patients with Crohn's disease, and histologically normal sections from patients with colonic cancer (n=7) and chronic severe constipation (n=1) as controls, were used in this study. PLA2-II-positive cells were detected by immunofluorescence and in situ hybridization. Metachromatic staining and esterase staining were used to identify mast cells and macrophages, respectively. It was shown that mast cells and macrophages in the ileal submucosa in both patients and controls showed positive PLA2-II staining. The number of PLA2-II-labeled cells that did not react with metachromasia, e.g. macrophages, was significantly greater in inflamed Crohn's disease compared to controls. This is, to our knowledge, the first study that has described the presence in healthy, while presence and upregulation of PLA2-II-positive cells in inflamed human ileal submucosa. Our findings suggest a proinflammatory potential for secretory PLA2-II in submucosa, while proinflammatory stimulation of mast cells and macrophages in vitro has shown that the enzyme is responsible for delayed prostaglandin formation.

Adolescent↗

PubMed1999

MHC-I-induced apoptosis in human B-lymphoma cells is dependent on protein tyrosine and serine/threonine kinases.

In addition to providing the framework for peptide presentation, major histocompatibility complex class I (MHC-I) molecules can act as signal transducing molecules in lymphoid cells. Here we show that the mobilization of intracellular calcium, which follows crosslinking of MHC-I molecules on human B lymphoma cells, is dependent on protein tyrosine kinases and the phosphatidylinositol 3 (PI-3) kinase. Functional studies showed that MHC-I crosslinking induced almost complete inhibition of the spontaneous proliferation of the B lymphoma cells as early as 6 h post-crosslinking and apoptosis 24 h post-crosslinking. Preincubation with either protein tyrosine kinase or protein serine/threonine kinase inhibitors reduced the MHC-I-induced apoptosis to background levels, whereas inhibition of PI-3 kinase had no effect. These data demonstrate a pivotal role for protein tyrosine and serine/threonine kinases in MHC-I-mediated apoptosis in human B-cells and suggest the presence of several MHC-I signaling pathways leading to diverse effects in these cells.

Androstadienes↗