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Effect of connexin 43 inhibition by the mimetic peptide Gap27 on corneal wound healing, inflammation and neovascularization
Taibah University, Saudi Arabia; Veneto Eye Bank Fdn, Italy.
Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Ophthalmology in Linköping.
Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Ophthalmology in Linköping.ORCID iD: 0000-0001-8722-9155
Veneto Eye Bank Fdn, Italy.
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2016 (English)In: British Journal of Pharmacology, ISSN 0007-1188, E-ISSN 1476-5381, Vol. 173, no 19, p. 2880-2893Article in journal (Refereed) Published
Abstract [en]

Background and PurposeThe connexin 43 (Cx43) mimetic peptide Gap27 was designed to transiently block the function of this gap junction. This study was undertaken to investigate the effect of Gap27 on corneal healing, inflammation and neovascularization. Experimental ApproachThe effect of Gap27 on wound healing, inflammation and vascularization was assessed in primary human corneal epithelial cells (HCEC) in vitro and whole human corneas ex vivo, and in an in vivo rat wound healing model. Key ResultsGap27 enhanced the wound closure of HCEC in vitro and accelerated wound closure and stratification of epithelium in human corneas ex vivo, but did not suppress the corneal release of inflammatory mediators IL-6 or TNF- in vivo. In human corneas ex vivo, F4/80 positive macrophages were observed around the wound site. In vivo, topical Gap27 treatment enhanced the speed and density of early granulocyte infiltration into rat corneas. After 7days, the expressions of TNF- and TGF1 were elevated and correlated with inflammatory cell accumulation in the tissue. Additionally, Gap27 did not suppress VEGF release in organotypic culture, nor did it suppress early or late VEGFA expression or neovascularization in vivo. Conclusions and ImplicationsGap27 can be effective in promoting the healing of superficial epithelial wounds, but in deep stromal wounds it has the potential to promote inflammatory cell migration and accumulation in the tissue and does not suppress the subsequent neovascularization response. These results support the proposal that Gap27 acts as a healing agent in the transient, early stages of corneal epithelial wounding.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2016. Vol. 173, no 19, p. 2880-2893
National Category
Ophthalmology
Identifiers
URN: urn:nbn:se:liu:diva-132050DOI: 10.1111/bph.13568ISI: 000383668900006PubMedID: 27472295OAI: oai:DiVA.org:liu-132050DiVA, id: diva2:1038578
Note

Funding Agencies|European Union - Regional, National and International Programs Initiative for the Mobility and Development of researchers careers (I-MOVE) [267232]; European Cooperation in Science and Technology (EU-COST) program [BM1302, COST-STSM-BM1302-24766]

Available from: 2016-10-19 Created: 2016-10-17 Last updated: 2019-04-18
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)
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Available from: 2019-04-30 Created: 2019-04-18 Last updated: 2019-04-30Bibliographically approved

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Mirabelli, PierfrancescoXeroudaki, MariaLagali, Neil
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Division of Neuro and Inflammation ScienceFaculty of Medicine and Health SciencesDepartment of Ophthalmology in Linköping
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