| 1. |
- Ahl, David, et al.
(författare)
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Turning Up the Heat : Local Temperature Control During in vivo Imaging of Immune Cells
- 2019
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Ingår i: Frontiers in Immunology. - : FRONTIERS MEDIA SA. - 1664-3224. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Intravital imaging is an invaluable tool for studying the expanding range of immune cell functions. Only in vivo can the complex and dynamic behavior of leukocytes and their interactions with their natural microenvironment be observed and quantified. While the capabilities of high-speed, high-resolution confocal and multiphoton microscopes are well-documented and steadily improving, other crucial hardware required for intravital imaging is often developed in-house and less commonly published in detail. In this report, we describe a low-cost, multipurpose, and tissue-stabilizing in vivo imaging platform that enables sensing and regulation of local tissue temperature. The effect of tissue temperature on local blood flow and leukocyte migration is demonstrated in muscle and skin. Two different models of vacuum windows are described in this report, however, the design of the vacuum window can easily be adapted to fit different organs and tissues.
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| 2. |
- Liu, Haoyu, et al.
(författare)
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Distinct B cell subsets in Peyer's patches convey probiotic effects by Limosilactobacillus reuteri
- 2021
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Ingår i: Microbiome. - : Springer Nature. - 2049-2618. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Intestinal Peyer's patches (PPs) form unique niches for bacteria-immune cell interactions that direct host immunity and shape the microbiome. Here we investigate how peroral administration of probiotic bacterium Limosilactobacillus reuteri R2LC affects B lymphocytes and IgA induction in the PPs, as well as the downstream consequences on intestinal microbiota and susceptibility to inflammation.Results: The B cells of PPs were separated by size to circumvent activation-dependent cell identification biases due to dynamic expression of markers, which resulted in two phenotypically, transcriptionally, and spatially distinct subsets: small IgD(+)/GL7(-)/S1PR1(+)/Bcl6, CCR6-expressing pre-germinal center (GC)-like B cells with innate-like functions located subepithelially, and large GL7(+)/S1PR1(-)/Ki67(+)/Bcl6, CD69-expressing B cells with strong metabolic activity found in the GC. Peroral L. reuteri administration expanded both B cell subsets and enhanced the innate-like properties of pre-GC-like B cells while retaining them in the sub-epithelial compartment by increased sphingosine-1-phosphate/S1PR1 signaling. Furthermore, L. reuteri promoted GC-like B cell differentiation, which involved expansion of the GC area and autocrine TGF beta-1 activation. Consequently, PD-1-T follicular helper cell-dependent IgA induction and production was increased by L. reuteri, which shifted the intestinal microbiome and protected against dextran-sulfate-sodium induced colitis and dysbiosis.Conclusions: The Peyer's patches sense, enhance and transmit probiotic signals by increasing the numbers and effector functions of distinct B cell subsets, resulting in increased IgA production, altered intestinal microbiota, and protection against inflammation.
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| 3. |
- Lomei, Jalal, 1980-, et al.
(författare)
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Characterization of pro-angiogenic neutrophils
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 4. |
- Massena, Sara, et al.
(författare)
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Identification and characterization of VEGF-A-responsive neutrophils expressing CD49d, VEGFR1, and CXCR4 in mice and humans
- 2015
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 126:17, s. 2016-2026
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Tidskriftsartikel (refereegranskat)abstract
- Vascular endothelial growth factor A (VEGF-A) is upregulated during hypoxia and is the major regulator of angiogenesis. VEGF-A expression has also been found to recruit myeloid cells to ischemic tissues where they contribute to angiogenesis. This study investigates the mechanisms underlying neutrophil recruitment to VEGF-A as well as the characteristics of these neutrophils. A previously undefined circulating subset of neutrophils shown to be CD49d(+)VEGFR1(high)CXCR4(high) was identified in mice and humans. By using chimeric mice with impaired VEGF receptor 1 (VEGFR1) or VEGFR2 signaling (Flt-1tk(-/-), tsad(-/-)), we found that parallel activation of VEGFR1 on neutrophils and VEGFR2 on endothelial cells was required for VEGF-A-induced recruitment of circulating neutrophils to tissue. Intravital microscopy of mouse microcirculation revealed that neutrophil recruitment by VEGF-A versus by the chemokine macrophage inflammatory protein 2 (MIP-2 [CXCL2]) involved the same steps of the recruitment cascade but that an additional neutrophil integrin (eg, VLA-4 [CD49d/CD29]) played a crucial role in neutrophil crawling and emigration to VEGF-A. Isolated CD49d(+) neutrophils featured increased chemokinesis but not chemotaxis compared with CD49d(-) neutrophils in the presence of VEGF-A. Finally, by targeting the integrin α4 subunit (CD49d) in a transplantation-based angiogenesis model that used avascular pancreatic islets transplanted to striated muscle, we demonstrated that inhibiting the recruitment of circulating proangiogenic neutrophils to hypoxic tissue impairs vessel neoformation. Thus, angiogenesis can be modulated by targeting cell-surface receptors specifically involved in VEGF-A-dependent recruitment of proangiogenic neutrophils without compromising recruitment of the neutrophil population involved in the immune response to pathogens.
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| 5. |
- Nikpour, Maryam, et al.
(författare)
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Shb deficiency in endothelium but not in leukocytes is responsible for impaired vascular performance during hindlimb ischemia.
- 2015
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 214:2, s. 200-209
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Myeloid cells have been suggested to participate in angiogenesis and regulation of vascular function. Shb-deficient mice display both vascular and myeloid cell abnormalities with possible consequences for recovery after hindlimb ischemia. This study was conducted in order to assess the contribution of Shb-deficiency in myeloid cells to impaired vascular function in ischemia. Methods: Wild type and Shb-deficient mice were subjected to peritoneal VEGFA followed by intraperitoneal lavage, after which blood and peritoneal cells were stained for myeloid markers. VEGFA-induced leukocyte recruitment to cremaster muscle was investigated using intravital microscopy of both mouse strains. Blood flow after femoral artery ligation was determined on chimeric mice after bone marrow transplantation. Results: No differences in neutrophil numbers or cell surface phenotypes were detected. Moreover, neutrophil extravasation in VEGFA-activated cremaster muscle was unaffected by Shb deficiency. However, blood and peritoneal CXCR4+ monocytes/macrophages were reduced in response to intraperitoneal VEGFA but not LPS in the absence of Shb. Furthermore, the macrophage population in ischemic muscle was unaffected by Shb-deficiency after two days but reduced seven days after injury. The bone marrow transplantation experiments revealed that mice with wild type vasculature showed better blood flow than those with Shb-deficient vasculature irrespective of leukocyte genotype. Conclusion: The observed aberrations in myeloid cell properties in Shb-deficient mice are likely consequences of an abnormal vascular compartment and are not responsible for reduced muscle blood flow. Structural vascular abnormalities seem to be the primary cause of poor vascular performance under provoked vascular stress in this genetic model.
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| 10. |
- Seignez, Cedric, et al.
(författare)
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The multitasking neutrophils and their involvement in angiogenesis
- 2017
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Ingår i: Current opinion in hematology. - 1065-6251 .- 1531-7048. ; 24:1, s. 3-8
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Forskningsöversikt (refereegranskat)abstract
- Purpose of reviewThis review describes the mechanisms by which neutrophils contribute to angiogenesis in hypoxic tissues during different conditions and diseases (e.g., menstrual cycle, wound healing, ischemic diseases, cancers), with particular focus on the recently described proangiogenic neutrophil subpopulation.Recent findingsThe importance of neutrophils in initiation of angiogenesis has been described during the past decade, and is believed to occur through release of the well-known proangiogenic factors Bv8, vascular endothelial growth factor A, and matrix metalloproteinase 9. However, additional proangiogenic actions of neutrophils have been outlined this year, mediated through for example pyruvate kinase M2, 14,15-epoxyeicosatrienoic acid, and formation of neutrophil extracellular traps, although their distinct mechanisms of action remain partly unknown. Neutrophils can also limit angiogenesis by secreting for example neutrophil elastase and -defensins, which generate angiostatic molecules and proteolytically inactivate proangiogenic factors, respectively. These opposing neutrophil actions can be the consequence of on-site education or recruitment of distinct subpopulations from circulation. Indeed, a circulating proangiogenic neutrophil subpopulation was recently described in mice and men, which was rapidly recruited to hypoxic tissues by vascular endothelial growth factor A.SummaryThese recent findings have highlighted the diversity of actions performed by neutrophils in the angiogenic process and identified new opportunities to regulate angiogenesis.
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