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Early effects of dexamethasone and anti-VEGF therapy in an inflammatory corneal neovascularization model
Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Ophthalmology in Linköping.
Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Ophthalmology in Linköping.
Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Ophthalmology in Linköping.ORCID iD: 0000-0001-8722-9155
Linköping University, Department of Clinical and Experimental Medicine, Division of Neuroscience. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Anaesthetics, Operations and Specialty Surgery Center, Department of Ophthalmology in Linköping.
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2014 (English)In: Experimental Eye Research, ISSN 0014-4835, E-ISSN 1096-0007, Vol. 125, p. 118-127Article in journal (Refereed) Published
Abstract [en]

Inflammatory angiogenesis is the pathogenic mechanism of various sight-threatening eye diseases, among them corneal neovascularization. Current treatment options include steroids which have undesirable side effects, or anti-VEGF which has only limited efficacy. In an inflammatory environment, however, angiogenesis can be stimulated by numerous factors not directly targeted by anti-VEGF therapy. The aim of this study was to induce corneal inflammation leading to angiogenesis, and investigate the early, differential effects of steroid and anti-VEGF therapy at the cellular, tissue, and gene expression levels. Fifty-two Wistar rats received a single intrastromal corneal suture to induce a controlled inflammatory angiogenic response. Rats were subsequently treated with dexamethasone, rat specific anti-VEGF, or goat IgG (control), topically 4 times daily for 7 days. In vivo confocal microscopy of the cornea was performed longitudinally from 5 h up to 7 d to investigate morphology at the cellular and tissue-level. In vivo photographic vessel analysis and immunohistochemistry were also performed. RT-PCR for VEGF-A, FGF-2, IL-6, TNF-alpha, CXCL2, CCL2, CCL3 and DLL4 was performed at 24 h, and for VEGF-A, IL-6, TNF-alpha, FGF-2, CXCL2, CCL2, and CCL3 at 7 days. Early infiltration of CD11b + myeloid cells into the cornea at 5 h post-suture was delayed by both treatments relative to controls; however neither treatment was able to suppress accumulation of myeloid cells at day 2 or 7. Limbal vessel dilation was inhibited at 5 h by both treatments, but only dexamethasone showed sustained effect until day 2. Early macrophage recruitment was also suppressed by dexamethasone (but not by anti-VEGF) until day 2. Dexamethasone furthermore suppressed corneal neovascularization at day 7 by over 90%, whereas suppression by anti-VEGF was 14%. Despite differential suppression of vessel dilation, macrophage recruitment, and vascular invasion, anti-VEGF and dexamethasone both down-regulated VEGF-A and IL-6 expression at 24 h with sustained effect to 7 d. They also both down regulated FGF-2 and TNF-alpha at 24 h and CCL2 at 7 d. In conclusion, anti-angiogenic treatments influence early, pre-angiogenic tissue activity such as limbal vessel dilation, inflammatory cell infiltration of the stroma, and macrophage recruitment. Importantly, the differential effects of steroids and anti-VEGF treatment in suppressing neovascular growth could not be attributed to differential inhibition of several major angiogenic and inflammatory factors in the early pre-sprouting phase, including IL-6, VEGF-A, FGF-2, TNF-alpha, CCL2, CCL3, CXCL2, or DLL4.

Place, publisher, year, edition, pages
Elsevier, 2014. Vol. 125, p. 118-127
Keywords [en]
angiogenesis; neovascularization; cornea; inflammation; dexamethasone; anti-VEGF; confocal microscopy; rat
National Category
Clinical Medicine
Identifiers
URN: urn:nbn:se:liu:diva-110279DOI: 10.1016/j.exer.2014.06.006ISI: 000340079300014PubMedID: 24933712OAI: oai:DiVA.org:liu-110279DiVA, id: diva2:744045
Note

Funding Agencies|Crown Princess Margaretas Foundation; County Council of Ostergotland; Swedish Research Council [2012-2472]

Available from: 2014-09-05 Created: 2014-09-05 Last updated: 2019-04-18Bibliographically approved
In thesis
1. Inhibitors of corneal inflammation and angiogenesis: Prospectives and challenges
Open this publication in new window or tab >>Inhibitors of corneal inflammation and angiogenesis: Prospectives and challenges
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Pathologic angiogenesis is involved in cancer and several blinding conditions such as wet age-related macular degeneration, proliferative retinopathies and corneal neovascularization.

In these dieseases, the angiogenic triggers are hypoxia and inflammation, and both involve the main angiogenic mediator, which is Vascular Endothelial Growth Factor (VEGF). Among available treatments, anti-VEGF often shows limited or temporary efficacy, while steroids are potentially responsible for many side-effects. This thesis presents a series of linked studies aimed at elucidating the early pathologic changes leading to inflammation and corneal neovascularization, and how various treatments affect this process. In this thesis, anti-inflammatory and anti-angiogenic treatments are applied in corneal neovascularization models, to identify VEGF-independent pathways and other novel factors as future therapy targets, as well as to investigate the endogenous modulation of angiogenesis.

A model of experimental neovascularization in the rat cornea was used as main model, where the neovascular response is triggered by a surgical suture placed into the cornea. Investigational treatments (anti-Vegf, dexamethasone, IMD0354, Gap27, or control substances) were then given topically, with the exception of IMD0354, which was given systemically. The effects in the cornea were studied in vivo with slit lamp photography to assess and quantify macroscopic vessel growth and using in vivo confocal microscopy (IVCM) to study cell infiltration and limbal vessel dilation and detect microscopic vessel sprouts; these examinations were performed longitudinally. Genomic analysis with RNA microarray, selected gene expression with q-RT-PCR, and selected protein expression in tissue (immunohistochemistry, immunofluorescence, Western blot) were performed at different time-points. Moreover, other experiments on cell cultures (HUVEC and HCEC), organ cultures (human corneas), ex vivo models (aortic rings) and in vivo studies (zebrafish vasculogenesis) were performed.

Dexamethasone suppressed limbal vasodilation and corneal neovascularization more than anti-Vegf, despite no difference in inflammatory cell infiltration into the cornea. Five-hundred eleven fewer genes were differentially expressed in dexamethasone-treated corneas relative to naïve corneas, compared to anti-Vegf. Among them, several major pro-angiogenic and pro-inflammatory factors and chemokines were suppressed only by dexamethasone and represent novel candidate factors to target in order to improve anti-VEGF treatment. On the other hand, selective inhibition of a single inflammatory pathway (NF-κB), despite showing similar early effects as dexamethasone in suppressing tissue inflammation, was not effective enough to suppress new vessel growth. The same factors suppressed by dexamethasone are also inhibited in endogenous modulation of angiogenesis. Surprisingly, dexamethasone activated several complement factors, which could possibly be beneficial in the anti-angiogenic response.

In a different therapeutic approach, promoting cell migration to accelerate epithelial wound closure similarly was not sufficient to avoid inflammation and angiogenesis in the cornea.

In conclusion, new and more effective treatments are needed for corneal inflammation and neovascularization with fewer side-effects. In this thesis, several novel factors and mechanisms related to inflammation are identified, factors that are not addressed by anti-Vegf therapy, and therefore represent interesting objects for further study, as they have the potential to be targets for adjuvant therapy. Specific anti-inflammatory treatment as well as therapeutic activation of endogenous regulatory pathways, and potentially complement modulation, might represent new strategies to improve anti-angiogenic therapy, but when used alone they do not seem to avoid corneal neovascularization.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2019. p. 91
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1685
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:liu:diva-156415 (URN)10.3384/diss.diva-156415 (DOI)9789176850640 (ISBN)
Public defence
2019-05-17, Nils Holgersalen, Campus US, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2019-04-30 Created: 2019-04-18 Last updated: 2019-04-30Bibliographically approved

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Bourghardt Peebo, BeatriceXeroudaki, MariaKoulikovska, MarinaLagali, Neil

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Mirabelli, PierfrancescoBourghardt Peebo, BeatriceXeroudaki, MariaKoulikovska, MarinaLagali, Neil
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