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Wilsson, Åsa
Publications (7 of 7) Show all publications
Nilsdotter-Augustinsson, Å., Wilsson, Å., Larsson, J., Stendahl, O., Öhman, L. & Lundqvist Gustafsson, H. (2004). Staphylococcus aureus, but not Staphylococcus epidermidis, modulates the oxidative response and induces apoptosis in human neutrophils. Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), 112(2), 109-118
Open this publication in new window or tab >>Staphylococcus aureus, but not Staphylococcus epidermidis, modulates the oxidative response and induces apoptosis in human neutrophils
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2004 (English)In: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS), ISSN 0903-4641, E-ISSN 1600-0463, Vol. 112, no 2, p. 109-118Article in journal (Refereed) Published
Abstract [en]

S. epidermidis is the most common isolate in foreign body infections. The aim of this study was to understand why S. epidermidis causes silent biomaterial infections. In view of the divergent inflammatory responses S. epidermidis and S. aureus cause in patients, we analyzed how they differ when interacting with human neutrophils. Neutrophils interacting with S. epidermidis strains isolated either from granulation tissue covering infected hip prostheses or from normal skin flora were tested by measuring the oxidative response as chemiluminescence and apoptosis as annexin V binding. Different S. aureus strains were tested in parallel. All S. epidermidis tested were unable to modulate the oxidative reaction in response to formyl-methionyl-leucyl-phenylalanine (fMLP) and did not provoke, but rather inhibited, apoptosis. In contrast, some S. aureus strains enhanced the oxidative reaction, and this priming capacity was linked to p38-mitogen-activated-protein-kinase (p38-MAPK) activation and induction of apoptosis. Our results may explain why S. epidermidis is a weak inducer of inflammation compared to S. aureus, and therefore responsible for the indolent and chronic course of S. epidermidis biomaterial infections.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-23732 (URN)10.1111/j.1600-0463.2004.apm1120205.x (DOI)3239 (Local ID)3239 (Archive number)3239 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved
Lundqvist-Gustafsson, H., Norrman, S., Nilsson, J. & Wilsson, Å. (2001). Involvement of p38-mitogen-activated protein kinase in staphylococcus aureus-induced neutrophil apoptosis. Journal of Leukocyte Biology, 70(4), 642-648
Open this publication in new window or tab >>Involvement of p38-mitogen-activated protein kinase in staphylococcus aureus-induced neutrophil apoptosis
2001 (English)In: Journal of Leukocyte Biology, ISSN 0741-5400, E-ISSN 1938-3673, Vol. 70, no 4, p. 642-648Article in journal (Refereed) Published
Abstract [en]

Apoptosis occurred in human neutrophils within an hour of exposure to viable serumopsonized Staphylococcus aureus, as indicated by appearance of cells with condensed nuclei, fragmented DNA, and increased phosphatidylserine exposure. In contrast, serum-opsomized, heat-killed S. aureus did not induce apoptosis. This discrepancy could not be explained by differences in bacterial uptake or total NADPH-oxidase activity. Suppressing phagocytosis by pretreating the neutrophils with cytochalasin b or by using nonopsonized bacteria did not prevent apoptosis. A supernatant from bacteria grown for 2 h in nutrient broth had a strong proapoptotic influence that was abrogated by heat treatment. Exposure to viable S. aureus or supernatant also led to activation of p38-mitogen-activated protein kinase in the neutrophils. Inhibition of this kinase with SB203580 reduced the apoptosis-inducing capacity of both bacteria and supernatant. We conclude that S. aureus activates p38-mitogen-activated protein kinase in neutrophils and induces apoptosis, probably mediated by a bacteria-derived soluble factor(s).

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-27857 (URN)12617 (Local ID)12617 (Archive number)12617 (OAI)
Available from: 2009-10-08 Created: 2009-10-08 Last updated: 2017-12-13Bibliographically approved
Wilsson, Å. (2000). On the interaction between human neutrophils and Staphylococcus aureus. (Doctoral dissertation). Linköping: Linköpings universitet
Open this publication in new window or tab >>On the interaction between human neutrophils and Staphylococcus aureus
2000 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Intracellular free calcium is a key second messenger and has been shown to regulate several crucial functions in human neutrophils. The results show that a rise in [Ca2+], is an absolute requirement for efficient killing of serum-opsonized Staphylococcus aureus by human neutrophils. The reduced killing in the absence of Ca2+ was not due to an inhibited ingestion of the S. aureus bacteria but to impairment of the subsequent production of oxygen radicals.

S. aureus is a bacterium which binds to extracellular matrix proteins such as vitronectin. When studying the role of Ca2+ during phagocytosis of S. aureus adherent to vitronectin-coated surfaces, the results show that a rise in [Ca2+], is not a prerequisite for ingestion per se. However, Ca2+ control neutrophil migration on vitronectin, by regulating reversible integrindependent adhesion of the neutrophils.

The intracellular signalling events of the neutrophils induced by S. aureus were also evaluated. The results demonstrate that S. aureus induces both priming and apoptosis in the neutrophils. This was restricted to viable and not heat-killed bacteria. During priming tyrosine phosphorylation of PLCγ2 and Syk is increased. In addition, the Src-family protein kinase Lyn is activated as well by these bacteria. Inhibition of these proteins by selective drugs abrogates priming of the neutrophils, indicating that these proteins participate in neutrophil priming. Interaction of neutrophils with S. aureus as well as a S. aureus-derived factor induces apoptosis in the neutrophils, and this is regulated by p38 MAPK.

Taken together, this investigation shows that the Ca2+-dependent processing of bacteria by human neutrophils leads to several cellular responses affecting inflammation, such as oxidative activation, tyrosine phosphorylation, priming and apoptosis.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2000. p. 60
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 634
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-28652 (URN)13808 (Local ID)91-7219-735-8 (ISBN)13808 (Archive number)13808 (OAI)
Public defence
2000-05-30, Elsa Brändströmssalen, Hälsouniversitetet, Linköping, 09:00 (Swedish)
Opponent
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-08-10Bibliographically approved
Löfgren, R., Serrander, L., Forsberg, M., Wilsson, Å., Wasteson, Å. & Stendahl, O. (1999). CR3, FcγRIIA and FcγRIIIB induce activation of the respiratory burst in human neutrophils: the role of intracellular Ca2+, phospholipase D and tyrosine phosphorylation. Biochimica et Biophysica Acta. Molecular Cell Research, 1452(1), 46-59
Open this publication in new window or tab >>CR3, FcγRIIA and FcγRIIIB induce activation of the respiratory burst in human neutrophils: the role of intracellular Ca2+, phospholipase D and tyrosine phosphorylation
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1999 (English)In: Biochimica et Biophysica Acta. Molecular Cell Research, ISSN 0167-4889, E-ISSN 1879-2596, Vol. 1452, no 1, p. 46-59Article in journal (Refereed) Published
Abstract [en]

Human neutrophils express two different types of phagocytic receptors, complement receptors (CR) and Fc receptors. In order to characterize the different signaling properties of each receptor we have used non-adherent human neutrophils and investigated CR3, FcγRIIA and FcγRIIIB for their signaling capacity. Selective activation of each receptor was achieved by coupling specific antibodies to heat-killed Staphylococcus aureus particles, Pansorbins, through their Fc moiety. Despite the fact that these particles are not phagocytosed, we show that addition of Pansorbins with anti-CD18 antibodies recognizing CR3 induced prominent signals leading to a respiratory burst. Stimulation with anti-FcγRIIIB Pansorbins induced about half of the response induced by anti-CR3 Pansorbins, whereas anti-FcγRIIA Pansorbins induced an even weaker signal. However, FcγRIIA induced strong phosphorylation of p72syk whereas FcγRIIIB induced only a very weak p72syk phosphorylation. During CR3 stimulation no tyrosine phosphorylation of p72syk was seen. Both phospholipase D and NADPH oxidase activities were dependent on intracellular calcium. This is in contrast to tyrosine phosphorylation of p72syk that occurred even in calcium-depleted cells, indicating that oxygen metabolism does not affect p72syk phosphorylation. Inhibitors of tyrosine phosphorylation blocked the respiratory burst induced by both FcγRIIA and FcγRIIIB as well as CR3. This shows that tyrosine phosphorylation of p72syk is an early signal in the cascade induced by FcγRIIA but not by CR3.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-25448 (URN)10.1016/S0167-4889(99)00112-3 (DOI)9894 (Local ID)9894 (Archive number)9894 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved
Wilsson, Å., Lundqvist, H., Gustafsson, M. & Stendahl, O. (1996). Killing of phagocytosed Staphylococcus aureus by human neutrophils requires intracellular free calcium. Journal of Leukocyte Biology, 59(6), 902-907
Open this publication in new window or tab >>Killing of phagocytosed Staphylococcus aureus by human neutrophils requires intracellular free calcium
1996 (English)In: Journal of Leukocyte Biology, ISSN 0741-5400, E-ISSN 1938-3673, Vol. 59, no 6, p. 902-907Article in journal (Refereed) Published
Abstract [en]

The mobilization of intracellular calcium plays an important role in regulating neutrophil activation. With this in mind we investigated the effect of intra- and extracellular calcium on the ability of human neutrophils to kill complement-opsonized Staphylococcus aureus. We found that a rise in intracellular calcium is necessary for efficient killing of phagocytosed S. aureus. In the presence of extracellular calcium, killing of ingested bacteria in calcium-buffered neutrophils compared with normal cells was slightly reduced. Calcium buffering had no effect on phagocytic uptake by the neutrophils, but did decrease the generation of toxic oxygen metabolites, measured as chemiluminescence (CL). In nondepleted and calcium-depleted cells, removal of extracellular calcium did not affect ingestion but did cause a marked decrease in the ability to kill the bacteria. In parallel, the CL response was substantially reduced or completely blocked. These data show that calcium is not a prerequisite for phagocytosis of S. aureus by human neutrophils, but does play a vital role in the post-ingestion killing of the bacteria by regulating the generation of toxic oxygen metabolites.

Keywords
human leukocytes, ingestion, NADPH oxidase, respiratory burst, chemiluminescence
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-79586 (URN)A1996UV31300018 ()8691076 (PubMedID)
Available from: 2012-08-10 Created: 2012-08-10 Last updated: 2017-12-07Bibliographically approved
Wilsson, Å., Majeed, M. & Stendahl, O.Calcium requirements for vitronectin-mediated phagocytosis of Staphylococcus aureus by human neutrophils.
Open this publication in new window or tab >>Calcium requirements for vitronectin-mediated phagocytosis of Staphylococcus aureus by human neutrophils
(English)Manuscript (preprint) (Other academic)
Abstract [en]

In this paper we have shown that the intracellular free calcium concentration ([Ca2+]i) in human neutrophils regulates phagocytosis of Staphylococcus aureus adherent to vitronectin-coated surfaces. When neutrophils were allowed to phagocytose bacteria bound to vitronectin- or albumin-coated surfaces in tbe presence of Ca2+, there were no obvious differences in the phagocytic activity. Ca2+-depleted neut:ropbils showed a reduced phagocytic activity on vitronectin-coated surfaces. However, the phagocytosis on albumin-coated surfaces was unaffected. Adding extracellularly Ca2+ restored the reduced phagocytic activity in Ca2+-depleted neutrophils on vitronectincoated surfaces. Similarly, using a GRGDSP-peptide to block tbe RGDmediated integrin attachment of tbe neutrophils to vitronectin restored tbe reduced phagocytic activity in Ca2+-depleted cells. Studying phagocytosis in non-migrating neutrophils adherent to vitronectin showed that ingestion of S. aureus occurred independently of Ca2+. This indicate that Ca2+ regulate the phagocytic activity of neutrophils on vitronectin-coated surfaces by regulating integrin-dependent cell directed motility.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-79588 (URN)
Available from: 2012-08-10 Created: 2012-08-10 Last updated: 2012-08-10Bibliographically approved
Wilsson, Å., Stendahl, O. & Majeed, M.Enhancement of chemoattractant-induced oxidative activation during phagocytosis of Staphylococcus aureus by human neutrophils.
Open this publication in new window or tab >>Enhancement of chemoattractant-induced oxidative activation during phagocytosis of Staphylococcus aureus by human neutrophils
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Several studies have shown that the production of oxygen radicals in human neutrophils can be influenced by prior exposure to different priming agents, but the mechanism underlying priming is not fully understood. The present study shows that under reduced Ca2+-conditions, phagocytosis of viable, but not heat-killed S. aureus can prepare Ca2+-depleted neutrophils for an increased oxidative activation when stimulated with fMLP in the presence of Ca2+. This enhancement of the produced oxygen radicals, induced by viable S. aureus, was not due to differences in phagocytic uptake between viable or heat-killed bacteria by the neutrophils. We could neither detect any difference in the upregulation of chemoattractant receptors such as the fMLP receptor or complement receptor 3 (CR3) to the neutrophil cell surface. Phagocytosis of viable S. aureus by Ca2+-depleted neutrophils under reduced Ca2+-conditions, induced tyrosine phosphorylation of two proteins identified as phospholipase Cγ2 (PLCγ2) and Syk. Pretreatment of neutrophils with U-73122 or piceatannol, to selectively inhibit PLC and Syk, respectively, resulted in a marked suppression of the oxidative response in primed neutrophils. In addition, PP1, a drug known to selectively inhibit Srcfamily protein kinases inhibited the oxidative response in primedneutrophils. Moreover, bacterial uptake activated the Src- family protein kinase Lyn, which was inhibited by PPl. Phagocytosis of viable or heatkilled S. aureus did not show any difference in activation of p38 mitogenactivated protein kinase (MAPK) and inhibition of this kinase by SB203580 did not suppress the fMLP-induced oxidative activation inprimed neutrophils. The findings demonstrate that both priming and the induction of tyrosine phosphorylation of PLCγ2, Syk and Lyn are Ca2+-independent events, thus indicating that the phosphorylation of these intracellular targets plays a central role during the neutrophil priming by S. aureus.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-79589 (URN)
Available from: 2012-08-10 Created: 2012-08-10 Last updated: 2012-08-10Bibliographically approved
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