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Phospholipase A2 expression in the human nasal mucosa
Linköping University, Department of Molecular and Clinical Medicine, Occupational and Environmental Medicine. Linköping University, Faculty of Health Sciences.
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Phospholipase A2 (PLA2) is a superfamily of enzymes that promote inflammation by releasing arachidonic acid for the synthesis of eicosanoids and lysophospholipid for the synthesis of platelet-activating factor (PAF). On the other hand, several members of the PLA2 family (VIIA, VIIB, VIIIA and VIIIB) are able to degrade PAF and are therefore potentially important anti-inflammatory enzymes. The precise roles of the different PLA2 enzymes in airways inflammation are not known and the gene expression of the different PLA2s in the human nasal mucosa has not previously been examined. Using reversed transcription-polymerase chain reaction (RT-PCR) techniques, this thesis investigated (i) the occurrence of mRNAs for different PLA2 types in the nasal mucosa of healthy subjects; (ii) the effects of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) on the gene expression of different PLA2s in human nasal epithelial cells (RPMI 2650); (iii) the effects of IFN-γ and lipopolysaccharide (LPS) on the gene expression of different PLA2 types in human monocyte-derived macrophages; (iv) the effects of exudates from LPS- or ß-glucan exposed macrophages on the gene expression of different PLA2 types in RPMI 2650 cells, and (v) the levels of different PLA2 mRNAs in the nasal mucosa of patients with seasonal allergic rhinitis (SAR) and healthy controls. The relative abundances of the different PLA2 transcripts in normal human nasal mucosa were found to be X ≈ IVA > IIA ≈ IIE ≈ IVB ≈ VI > IB ≈ IID ≈ III ≈ IVC ≈ VII ≈ VIB. In RPMI 2650 cells, TNF-α increased the expression of PLA2 IVA and IVC, while IFN-γ increased the expression of PLA2 IIA and IID. In macrophages, IFN-γ increased the expression of both PLA2 IID and IVA while LPS increased the expression of PLA2 IVA but decreased that of IID. Medium from macrophages exposed to LPS or ß-glucan increased the expression of PLA2 IVC in RPMI 2650 cells; this upregulation was abrogated by antibodies to TNF-α and by the nuclear factor (NF)-κB inhibitor, pyrrolidine dithiocarbamate. Notably, the mRNA levels of PLA2 VIIA (PAF acetylhydrolase I) were lower in SAR patients than controls during both the pollen season and the off-season for pollen. These findings demonstrate that a large number of PLA2 types are constitutively expressed in the normal human nasal mucosa, including the newly discovered PLA2 types IID, IIE, IIF, III, IVB, IVC, VIB, X, XIIA, and XIIB. They also demonstrate that TNF-α and IFN-γ cause increased gene expression of two novel cytosolic and secretory PLA2 types (IVC and IID, respectively) in human nasal epithelial cells, suggesting that these PLA2 types may be involved in cytokine-mediated inflammation in the nasal mucosa. Moreover, the findings indicate that both LPS- and ß-glucan-activated macrophages can induce the gene expression of PLA2 IVC in nasal epithelial cells, and that this upregulation is mediated through TNF-α and under NF-κB control. The observation that PAF acetylhydrolase mRNA expression in the nasal mucosa is lower in SAR patients than in healthy subjects points to the possibility that impaired ability to inactivate PAF might be of importance in SAR.

Place, publisher, year, edition, pages
Linköping: Linköping University , 2004. , 100 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 864
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-22294Local ID: 1480ISBN: 91-7373-838-7 (print)OAI: oai:DiVA.org:liu-22294DiVA: diva2:242607
Public defence
2004-11-11, Aulan, Hälsans hus, Hälsouniversitetet, Linköping, 09:00 (Swedish)
Opponent
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2012-10-29Bibliographically approved
List of papers
1. Expression of members of the phospholipase A2 family of enzymes in human nasal mucosa
Open this publication in new window or tab >>Expression of members of the phospholipase A2 family of enzymes in human nasal mucosa
2001 (English)In: European Respiratory Journal, ISSN 0903-1936, E-ISSN 1399-3003, Vol. 18, no 1, 130-138 p.Article in journal (Refereed) Published
Abstract [en]

Phospholipase A2 (PLA2) is a family of enzymes thought to play a key role in inflammation by releasing arachidonic acid for the synthesis of eicosanoids and lysophospholipid for the synthesis of platelet-activating factor. However, the precise contribution of different PLA2 types to the formation of inflammatory lipid mediators in the upper airways is not known and the expression of different PLA2 genes in the human nasal mucosa has not been examined.

This study therefore investigated the occurrence of messenger ribonucleic acids (mRNAs) for different PLA2 forms (IB, IIA, IID, IIE, III, IVA, IVB, IVC, V, VI, VII, X, acid calcium-independent (aiPLA2), and calcium-independent membrane bound PLA2, (iPLA2-2)) in the nasal mucosa of five healthy human subjects.

Using reversed transcription-polymerase chain reaction (RT-PCR) techniques it was found that all these PLA2 types except PLA2 V were expressed in all subjects, whereas PLA2 V was detected in only one individual on one single occasion. The relative abundance of the different PLA2 transcripts were aiPLA2>X≈IVA>IIA≈IIE≈IVB≈VI>IB≈IID≈III≈IVC≈VII≈iPLA2-2. To further quantify the mRNA-expression of PLA2 X, IVA and IIA, the samples were reanalysed with a quantitative PCR-technique utilizing competitive deoxyribonucleic acid (DNA) mimics as references. The amounts of PLA2 X, IVA and IIA mRNA were then estimated to 0.9±0.2, 1.1±0.7, and 0.0025±0.0021 amol (mean±se), respectively, confirming the relative abundance of these PLA2 transcripts and indicating that the recently described PLA2 X form is relatively strongly expressed.

These findings demonstrate that a large number of PLA2 types are expressed in the normal human nasal mucosa. Moreover, this investigation demonstrates, for the first time, the presence of the newly discovered phospholipase A2 forms IID, IIE, III, IVB, IVC, X and calcium-independent membrane bound phospholipase A2 in the human nasal mucosa and raises the possibility that one or several of these may be involved in inflammatory reactions in the nose.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-26015 (URN)10.1183/09031936.01.00054701 (DOI)10468 (Local ID)10468 (Archive number)10468 (OAI)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13
2. Increased gene expression of novel cytosolic and secretory phospholipase A2 types in human airway epithelial cells induced by tumor necrosis factor-α and IFN-γ
Open this publication in new window or tab >>Increased gene expression of novel cytosolic and secretory phospholipase A2 types in human airway epithelial cells induced by tumor necrosis factor-α and IFN-γ
2002 (English)In: Journal of Interferon and Cytokine Research, ISSN 1079-9907, E-ISSN 1557-7465, Vol. 22, no 9, 947-955 p.Article in journal (Refereed) Published
Abstract [en]

Phospholipase A2 (PLA2) is a growing family of enzymes that may play a major role in inflammation. We investigated the effect of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) on the gene expression of 19 different PLA2 types (IB, IIA, IID, IIE, IIF, III, IVA, IVB, IVC, V, VIA, VIB, VIIA, VIIB, VIIIA, VIIIB, X, XII, and XIII) in human bronchoepithelial (BEAS-2B) and nasal epithelial (RPMI 2650) cells. The cells were stimulated with TNF-α or IFN-γ for different lengths of time (1, 4, 18, and 48 h), and the mRNA levels of the different PLA2 types were determined by reverse transcriptase-PCR (RT-PCR) and normalized to those of the housekeeping gene, GAPDH. In both cell lines, TNF-α increased the expression of PLA2 IVA and IVC, and IFN-γ increased the expression of PLA2 IIA and IID. No influence on the gene expression of PLA2-activating protein (PLAP) was noted on cytokine stimulation. These findings indicate that TNF-α and IFN-γ induce gene expression of two novel cytosolic and secretory PLA2 types (IVC and IID, respectively) in human airway epithelial cells. The possibility that these PLA2 types are involved in cytokine-mediated inflammation in the respiratory tract is inferred.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-26517 (URN)10.1089/10799900260286650 (DOI)11075 (Local ID)11075 (Archive number)11075 (OAI)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13
3. Interferon γ-induced gene expression of the novel secretory phospholipase A2 type IID in human monocyte-derived macrophages is inhibited by lipopolysaccharide
Open this publication in new window or tab >>Interferon γ-induced gene expression of the novel secretory phospholipase A2 type IID in human monocyte-derived macrophages is inhibited by lipopolysaccharide
2005 (English)In: Inflammation, ISSN 0360-3997, E-ISSN 1573-2576, Vol. 29, no 2-3, 108-117 p.Article in journal (Refereed) Published
Abstract [en]

Phospholipase A2 (PLA2) is a superfamily of enzymes that may play a major role in airways inflammation. We investigated the effect of interferon-γ (IFN-γ) on the gene expression of 19 different PLA2 types in human monocyte-derived macrophages and nasal epithelial cells (RPMI 2650). The cells were stimulated with IFN-γ for different lengths of time (up to 48 h), and the mRNA levels of the different PLA2 types were determined by reverse transcriptase–PCR (RT-PCR) and normalized to those of the house-keeping gene, GAPDH. It appeared that IFN-γ clearly increased the expression of secretory PLA2 IID (but not IIA) in macrophages, while both PLA2 IID and IIA were upregulated in RPMI 2650 cells. Moreover, after 18 h, the mRNA levels of cytosolic PLA2 IVA were 2–3 times higher in IFN-γ-stimulated macrophages than controls, while there was no such effect of IFN-γ in RPMI 2650 cells. Lipopolysaccharide (LPS) augmented the increased gene expression of PLA2 IVA but decreased both the basal and the IFN-γ-induced PLA2 IID mRNA expression in macrophages (but not in RPMI 2650 cells). The NF-κB inhibitor Pyrrolidine dithiocarbamate (PDTC) and the phoshatidylinositol 3-kinase (PI3K) inhibitor wortmannin were employed to get an insight into the mechanism behind these observations. Incubation of macrophages with PDTC had no effect on the LPS impairment of PLA2 IID gene expression, but inhibited the LPS mediated activation of PLA2 IVA. No significant effect was noted of PDTC on IFN-γ stimulation, while PI3K had no effect at all on any of the stimuli used. Furthermore, LPS (but not IFN-γ) increased the mRNA levels of the nuclear factor (NF)-κB inhibitors α and ξ in macrophages, but not in RPMI 2650 cells. These findings indicate that (a) the gene expression of secretory types PLA2 IID and IIA in response to IFN-γ is much dependent on cell type, and (b) the regulation of PLA2 type IID in human macrophages is clearly different from that of PLA2 type IVA. (c) PLA2 IVA is probably under control of both NF-κB and IFN-γ-responsive elements (GRE) or IFN-γ-activating sites (GAS). The possibility that PLA2 IID is involved in cytokine-mediated inflammation in the nasal mucosa is inferred, as is the potential role of PLA2 IID in the host defense against LPS-containing bacteria.

Keyword
IFN-?, LPS, Macrophages, Nasal mucosa, PLA2
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-45483 (URN)10.1007/s10753-006-9007-x (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13
4. Lipopolysaccharide- and ß-glucan-stimulated macrophages upregulate cytolosic phospholipase A2 IVC in nasal epithelial cells: role of TNF-α
Open this publication in new window or tab >>Lipopolysaccharide- and ß-glucan-stimulated macrophages upregulate cytolosic phospholipase A2 IVC in nasal epithelial cells: role of TNF-α
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Phospholipase A2 (PLA2) is a superfamily of enzymes that may play a major role in airways inflammation. We investigated the gene expression of 20 different PLA2 types in nasal epithelial cells (RPMI 2650) before and after incubation with cell growth medium from human monocyte-derived macrophages exposed to lipopolysaccharide (LPS) or ß-1,3-D-glucan (ßG). The macropbages were exposed to LPS (10 µ/ml) or ßG (500 µg/ml) for 48 hours and the mRNA levels of the different PLA2 types in RPMI 2650 cells were determined after incubation for 18 hours using reverse transcriptase-PCR (RT-PCR). It appeared that the mRNA levels of PLA2 type IVC were significantly increased after incubation, both with medium from LPS-exposed and ßG-exposed macrophages. In both cases, the increased PLA2 IVA mRNA expression was abolished by TNF-α antibodies and by the NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC). There were no significant alterations in the mRNA levels of the other PLA2 types, including PLA2 IVA. These findings indicate that both LPS- and ßG-activated macrophages can induce the gene expression of PLA2 IVC in nasal epithelial cells, and that this upregulation is mediated through TNF-α and under NF-κB control. Further studies are required to clarify whether these mechanisms may operate to cause inflammation in the nasal mucosa in vivo.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-84953 (URN)
Available from: 2012-10-29 Created: 2012-10-29 Last updated: 2012-10-29
5. Phospholipase A2 mRNA expression in the nasal mucosa of healthy subjects and patients with seasonal allergic rhinitis
Open this publication in new window or tab >>Phospholipase A2 mRNA expression in the nasal mucosa of healthy subjects and patients with seasonal allergic rhinitis
Show others...
2004 (English)In: Rhinology, ISSN 0300-0729, E-ISSN 1996-8604, Vol. 42, no 2, 85-91 p.Article in journal (Refereed) Published
Abstract [en]

Phospholipase A2 (PLA2) is a family of enzymes that play different role(s) in inflammation, but their importance in seasonal allergic rhinitis (SAR) has not been clarified. Here, we determined the levels of messenger ribonucleic acid (mRNA) for different PLA2 types in the nasal mucosa of SAR patients (n=6) and healthy controls (n=5). Nasal brush samples were taken both during pollen season, when the symptoms of the patients were severe, and off-season, when the patients were free of symptoms. We found that PLA2 IB, IIA, IID,IIE, IIF III, IVA, IVB, IVC, VIA, VIB, VIIA, VIIB, VIIIA, VIIIB, X, XII and XIII were all expressed in each subject at both occasions. The mRNA levels of PLA2 VIIA (platelet-activating factor (PAF) acetylhydrolase) were lower in SAR patients than controls, both during pollen season (p = 0.03) and off season (p = 0.03). These findings demonstrate that a large number of PLA2 types are expressed in the nasal mucosa, regardless of whether there is ongoing allergic inflammation or not. The observation that PAF acetylhydrolase mRNA expression in the nasal mucosa is lower in SAR patients than in healthy subjects suggests the possibility that impaired ability to inactivate PAF might be of importance in SAR. Further studies are required to clarify whether the decreased PAF acetylhydrolase mRNA expression in SAR is accompanied by decreased enzyme activity and whether aberrations in PAF acetylhydrolase are present in infectious rhinitis patients as well.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-22328 (URN)15224635 (PubMedID)1528 (Local ID)1528 (Archive number)1528 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved

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