uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Functional characterization of pro-angiogenic neutrophils
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology. (Mia Phillipson)
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The vascular system stretches throughout the body to provide oxygen, nutrition, and to remove waste products from cell metabolism. Angiogenesis, formation of new blood vessels by sprouting from pre-existing vessels, is one of the main mechanisms involved in blood vessel formation. A successful angiogenic process is dependent on the timely involvement of several parameters; from different cell types to anti- and pro-angiogenic soluble factors.

White blood cells are mostly famous for being involved in host defense against pathogens, through rapid reactions by innate immunity and delayed but specific responses through adaptive immunity. The neutrophils are innate immune cells, which are the most abundant white blood cells in the circulation. In addition to their classical roles in defense against invading microorganisms, it was recently revealed that neutrophils actively contribute to angiogenesis. Neutrophils that are involved in angiogenesis comprise a specific population, namely pro-angiogenic neutrophils (PANs), that are recruited to sites of hypoxia by using different adhesion molecules compared to when they chemotax towards infection.

The present investigations focus on characterization of PANs and comparing them to the classic neutrophil population in terms of their physical features and their functions. By modifying and applying new in vivo and in vitro models of angiogenesis, interactions between growing endothelial cells and neutrophils have been further revealed, as well as neutrophil recruitment and movement towards an active site of angiogenesis. We found that the main neutrophil contribution to angiogenesis at site of islet transplantation occurs at early stages of revascularization to establish new vessels, where after the neutrophils leave the site. Neutrophil recruitment to a site of infection relies to a large extent on macrophage signals, but this was not the case when they were recruited to sites of hypoxia. PANs are a specific sub-population of neutrophils that significantly differ from the rest of the neutrophil population not only in terms of their active contribution to angiogenesis, but also in terms of their physical features and their phagocytosis abilities. The role of vascular endothelial growth factor receptor (VEGFR1) and also chemokine CXCL12 (CXCR4/CXCL12 signaling) in neutrophil recruitment has been further revealed by our in vitro model; neutrophil migration to sprouting endothelium is directed by CXCL12 and VEGFR1. Furthermore we found that hypoxic condition boosted pro-angiogenic activities of PANs. Moreover, how vascular permeability affects neutrophil recruitment was studied; vascular permeability regulates inflammation by increasing chemokine transport into the blood vessels and thereby promotes neutrophil recruitment.

In conclusion, functional characterization of pro-angiogenic neutrophils performed in this thesis demonstrates differences beyond marker expression when compared to classic neutrophils. Moreover, intricate interactions necessary for the formation of new blood vessels between neutrophils and the growing vasculature were shown. Increased understanding of the contribution of neutrophils to blood vessel formation in hypoxic environment or/and tumors could be exploited further to develop potential therapies.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. , p. 58
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1498
Keywords [en]
angiogenesis, leukocytes, neutrophils, pro-angiogenic neutrophils, islets transplantation, intravital microscopy, aortic ring assay, phagocytosis, ROS production, hypoxia, vascular permeability, neutrophil recruitment
National Category
Immunology in the medical area
Research subject
Medical Cell Biology
Identifiers
URN: urn:nbn:se:uu:diva-362217ISBN: 978-91-513-0457-1 (print)OAI: oai:DiVA.org:uu-362217DiVA, id: diva2:1253077
Public defence
2018-11-20, A1:107A, BMC, Husargatan 3, Uppsala, 09:30 (English)
Opponent
Supervisors
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationRagnar Söderbergs stiftelseAvailable from: 2018-10-30 Created: 2018-10-03 Last updated: 2018-11-26
List of papers
1. Vascular sprouts induce local attraction of proangiogenic neutrophils
Open this publication in new window or tab >>Vascular sprouts induce local attraction of proangiogenic neutrophils
Show others...
2017 (English)In: Journal of Leukocyte Biology, ISSN 0741-5400, E-ISSN 1938-3673, Vol. 102, p. 741-751Article in journal (Refereed) Published
National Category
Physiology Bioinformatics (Computational Biology)
Identifiers
urn:nbn:se:uu:diva-196483 (URN)10.1189/jlb.1MA0117-018R (DOI)000413395700019 ()
Projects
eSSENCE
Available from: 2017-06-05 Created: 2013-03-10 Last updated: 2018-11-12Bibliographically approved
2. Characterization of pro-angiogenic neutrophils
Open this publication in new window or tab >>Characterization of pro-angiogenic neutrophils
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The roles of neutrophils in immune defense have been investigated for decades. These cells are well equipped to protect the body in several ways against invaders such as microorganism. Recently it has been reported that neutrophils also contribute to angiogenesis; they are recruited to the site of hypoxia where they can promote blood vessel formation, as demonstrated both in vivo and in vitro. We found that these neutrophils with proangiogenic actions form a specific subset of the circulating neutrophils. The proangiogenic neutrophils (PANs) exclusively express the adhesion molecule CD49d and vascular endothelial growth factor receptor 1 (VEGFR1), and contribute to angiogenesis by delivering MMP-9 (matrix metalloproteinase 9). In this study, PANs were compared to classic neutrophils in respect to physical features as well as functionality. We found that PANs in humans were smaller and in human and mice PANs had higher granularity compared to the classic neutrophils. Moreover, they were more efficient phagocytes than classic neutrophils. In the aortic ring model of angiogenesis, vessel neo-formation was increased by the presence of pro-angiogenic neutrophils. Finally, by using neutrophils from mice with impaired VEGFR1 receptor (Flt-1 tk-/- mice) we demonstrated the role of VEGFR1 in neutrophil recruitment towards angiogenic endothelium. Together these results show clear differences between the pro-angiogenic subpopulation and the classic neutrophils, which further solidify the conclusion of a specific neutrophil subpopulation.

Keywords
Leukocytes, angiogenesis, phagocytosis, pro angiogenic neutrophils, ROS production
National Category
Immunology in the medical area
Research subject
Immunology; Biology with specialization in Molecular Immunology
Identifiers
urn:nbn:se:uu:diva-362053 (URN)
Funder
Knut and Alice Wallenberg FoundationRagnar Söderbergs stiftelse
Available from: 2018-10-02 Created: 2018-10-02 Last updated: 2018-12-04
3. Pro-angiogenic neutrophils are potentiated by hypoxia
Open this publication in new window or tab >>Pro-angiogenic neutrophils are potentiated by hypoxia
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Abstract

Hypoxia, shortage of oxygen in tissues, is closely related to injury, inflammation and tissue damage. One way to overcome this issue is increasing angiogenesis, growing new blood vessels from preexist-ing ones, at the site of hypoxia. Considerable number of cells, factors and signaling pathways are involved in regulating angiogenesis.

Neutrophils have been detected at the site of hypoxia and it has been shown that a subpopulation of these cells, pro-angiogenic neutrophils, PANs is actively involved in increasing angiogenesis. In this study, the effect of hypoxia on PANs was studied by co-culturing PANs with growing endothelial cells using in vitro angiogenesis assay and hypoxic and normoxic incubator. Moreover, life spans of neutrophils and PANs, as well as expression of PANs specific markers have been investigated under hypoxia and normoxia.  

Our data shows that the ability of PANs, to induce angiogenesis was increased under hypoxic conditions. Moreover larger number of PANs survived while co-culturing with active growing endothelial cells. We thereby conclude that the hypoxic microenvironment primes pro-angiogenic neutrophils increase their pro-angiogenic ability.

Keywords
Neutrophils, angiogenesi, hypoxia
National Category
Immunology in the medical area
Research subject
Immunology; Biology with specialization in Molecular Immunology
Identifiers
urn:nbn:se:uu:diva-362052 (URN)
Funder
Ragnar Söderbergs stiftelseKnut and Alice Wallenberg FoundationSwedish Research Council
Available from: 2018-10-02 Created: 2018-10-02 Last updated: 2018-10-03
4. Chemokine transport across the vessel wall and presentation to circulation leukocytes are regulated by vascular permeability, DARC and PAD released during inflammation
Open this publication in new window or tab >>Chemokine transport across the vessel wall and presentation to circulation leukocytes are regulated by vascular permeability, DARC and PAD released during inflammation
Show others...
(English)Manuscript (preprint) (Other (popular science, discussion, etc.))
Abstract [en]

Increased vascular permeability and consequent leakage of plasma and macromolecules through endothelial cell junctions is a hallmark of inflammation. The physiological importance of this event for leukocyte recruitment has been controversial, but it might have a role in chemokine transport into blood vessels and consequently for the recruitment of circulating leukocytes. Elevated amounts of peptidyl arginine deiminases (PAD) and of their citrullinated products associate with autoimmune disorders, chronic inflammation and cancer. The role of citrullination in the inflamed microenvironment is debated, but it might be an innate mechanism for infiltrating leukocytes to resolve inflammation. In this study we investigated if increased vascular permeability facilitated the influx of chemokines from tissue into post-capillary venules, thereby affecting leukocyte recruitment. Vascular permeability and chemokine influx into post-capillary venules were simultaneously monitored by real-time in vivo confocal microscopy of the mouse cremaster muscle. We found that increased venular permeability induced by histamine, correlated with accelerated influx of the fluorescently labeled chemokine CXC ligand 2 (CXCL2/MIP-2) into post-capillary venules, which accumulated predominantly at endothelial cell junctions. Consequently, neutrophil adhesion was accelerated leading to increased neutrophil extravasation. In situ inhibition of caveolae-mediated transcytosis by filipin had no significant effect on chemokine influx to post-capillary venules, indicating that chemokine traffic across the venular wall is independent of caveolar transport. Nevertheless, neutrophil recruitment was prevented in filipin-treated mice as transmigrating neutrophils were trapped on endothelial cell domes and failed to finalize transmigration. Furthermore, we used this real-time in vivo model for studying the role of the atypical chemokine receptor 1 (DARC/ACKR1) in chemokine transport and availability. We show that the absence of DARC/ACKR1 (ACKR1-/- mice) does not impair chemokine transport. Instead it leads to increased seric levels of chemokine and increased intravascular chemokine sequestration. As a result, high numbers of firmly adherent neutrophils were found in post-capillary venules. Intraluminal neutrophil crawling was though abrogated and neutrophil transmigration prevented. Finally, we studied the role of chemokine citrullination by leukocyte-derived PAD in the inflamed tissue. The transport of citrullinated CXC ligand 8 (CXCL8/IL-8) across the venular wall, its immobilization on the luminal endothelium, and subsequent leukocyte recruitment, were monitored by real time imaging. Chemokine citrullination inhibited its transport from the inflamed tissue into blood vessels, impeding their immobilization on the luminal endothelium. Reduced intravascular chemokine bioavailability dampened leukocyte recruitment. Altogether these findings demonstrate that changes in vascular permeability regulate inflammation by affecting abluminal-to-luminal chemokine transport and thereby leukocyte recruitment to tissue. Furthermore, DARC/ACKR1 plays an important role in neutrophil recruitment by controlling intravascular chemokine availability and by shaping the intravascular chemokine gradient necessary for efficient neutrophil recruitment. Finally, citrullination of chemokines by PAD in the inflamed tissue inhibits chemokine transport into blood vessels and luminal presentation to circulating leukocytes, which dampens leukocyte recruitment

Keywords
Vascular permeability, chemokine transport, DARC, Leukocyte recruitment
National Category
Immunology in the medical area
Research subject
Biology with specialization in Molecular Immunology; Biology with specialization in Molecular Immunology; Biology with specialization in Molecular Immunology
Identifiers
urn:nbn:se:uu:diva-362055 (URN)
Funder
Ragnar Söderbergs stiftelseKnut and Alice Wallenberg Foundation
Available from: 2018-10-02 Created: 2018-10-02 Last updated: 2018-10-03

Open Access in DiVA

fulltext(1666 kB)444 downloads
File information
File name FULLTEXT02.pdfFile size 1666 kBChecksum SHA-512
e86d6323f53939d124456ade0e56ff0de15808011a13f7d1ff89d001d05006ab2402c0dbbcdb952ac7305ebb8f8a46c5621f034b5f34d6ab1d8fc4d0d2ad5cbf
Type fulltextMimetype application/pdf
Buy this publication >>

Authority records BETA

Lomei, Jalal

Search in DiVA

By author/editor
Lomei, Jalal
By organisation
Department of Medical Cell Biology
Immunology in the medical area

Search outside of DiVA

GoogleGoogle Scholar
Total: 444 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 2804 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf