Fabio Bignami

Safety and efficacy of topical infliximab in a mouse model of ocular surface scarring.

PURPOSE To evaluate the safety/efficacy of topical infliximab, an anti-TNF-α monoclonal antibody, in a mouse model of ocular surface scarring. METHODS Twenty alkali burn mice were treated with infliximab (10 mg/mL) topically 6 times a day, while 20 alkali burn mice received saline for 7 days. Corneal opacity, epithelial wound healing, and ocular phimosis were examined at the slit-lamp. Tear production was quantified with phenol red thread test. Immunofluorescence for infliximab penetration, TNF-α localization, CD45+ cell infiltration, PAS, and Massons trichrome staining were evaluated on ocular globes and eyelids. TNF-α and IL-1β expression levels were measured on treated murine corneas and eyelids. Finally, quantification of corneal CD31+ blood vessels and LYVE1+ lymphatic vessels were evaluated on 10 additional alkali burn mice receiving either infliximab or saline, after 14 days. RESULTS Topical infliximab penetrated the cornea and the conjunctiva and was not toxic (negative fluorescein stain). Its molecular target, TNF-α, was detected in the cornea after injury. Infliximab significantly reduced corneal perforation, opacity index, phimosis, leukocyte infiltration, and fibrosis in the eyelids. It also significantly prevented goblet cell infiltration in epithelial cornea and loss in the conjunctiva (P < 0.05), improved tear secretion and epithelial healing (P < 0.05). Finally, it significantly reduced both corneal hem- (P < 0.05) and lymphangiogenesis (P < 0.01). CONCLUSIONS Infliximab penetrates the cornea and is safe to the ocular surface in an animal model of ocular surface scarring. We suggest that topical application of infliximab may be a useful treatment in ocular caustications.

Alkali burn versus suture-induced corneal neovascularization in C57BL/6 mice: an overview of two common animal models of corneal neovascularization.

The purpose of the present study was to quantify and compare corneal hem- and lymphangiogenesis between alkali burn and suture-induced corneal neovascularization (CNV) in two commonly used mouse strains. A retrospective analysis was performed on C57BL/6 and FVB neovascularized corneas. CNV was induced by surface caustication with NaOH or intrastromal placement of three 10.0 nylon sutures. Hemangiogenesis and lymphangiogenesis extent was calculated on whole mounted corneas by CD31 and LYVE1 immunofluorescence analysis. Blood vessel growth was similar between alkali burn and suture-induced CNV in C57BL/6 mice, and between C57BL/6 and FVB sutured strains. On the contrary, corneal lymphangiogenesis was more pronounced in the C57BL/6 sutured mice versus the alkali burn group, and in the FVB strain versus both C57BL/6 models. These results indicate that significant differences occur in lymphangiogenesis, but not hemangiogenesis, in the alkali burn and suture-induced models in C57BL/6 mice. Furthermore, lymphangiogenesis is more pronounced in the albino (FVB) strain after suture placement. We suggest that the suture model has a number of advantages and may be preferentially used to study corneal lymphangiogenesis.

NK1 receptor antagonists as a new treatment for corneal neovascularization.

PURPOSE To determine whether the inhibition of Substance P (SP) activity can reduce corneal neovascularization (CNV) by means of local administration of high-affinity, competitive, tachykinin 1 receptor (NK1R) antagonists Lanepitant and Befetupitant. METHODS We performed a safety and efficacy study by using (1) two different C57BL/6 mouse models of CNV: alkali burn and sutures; (2) different concentrations; and (3) different routes of administration: topical or subconjunctival. Clinical examination endpoints, SP levels, CNV index, and leukocyte infiltration were measured. RESULTS Substance P increased after injury in the corneal epithelium of both CNV models, and later in the suture model. Topical Lanepitant was nontoxic to the ocular surface and effective in reducing hemangiogenesis and lymphangiogenesis, corneal SP levels, and leukocyte infiltration, as soon as 4 days later in the alkali burn model. Topical Lanepitant, up to 7 days, was ineffective in the suture model. However, subconjunctival Lanepitant was effective in reducing lymphatic CNV, leukocyte infiltration, and SP levels in the suture model, after 10 days. Additionally, in the alkali burn model, subconjunctival Lanepitant significantly reduced blood CNV, corneal perforation rate, opacity, and leukocyte infiltration, and improved tear secretion. Finally, topical application of Befetupitant reduced CNV in the alkali burn model but was toxic owing to the vehicle (dimethyl sulfoxide [DMSO]); hence, Befetupitant was not tested in the suture model. CONCLUSIONS The NK1R antagonist Lanepitant is safe for the ocular surface and effective in reducing both corneal hemangiogenesis and lymphangiogenesis, and leukocyte infiltration. We suggest that inhibition of NK1R may represent an adjunctive tool in the treatment of CNV.

Ocular surface injury induces inflammation in the brain: in vivo and ex vivo evidence of a corneal-trigeminal axis.

PURPOSE To test whether a corneal injury can stimulate inflammation in the trigeminal ganglion (TG), a structure located in the brain. METHODS At 4 and 8 days after alkali burn induced in the right eyes of mice, in vivo magnetic resonance imaging (MRI) of the brain was done before and after ultrasmall superparamagnetic iron oxide nanoparticle (USPIO) contrast to track macrophages. Trigeminal ganglia were stained for Prussian Blue and inflammatory cell markers. Interleukin-1β, TNF-α, and VEGF-A transcripts were quantified on days 1, 4, and 8, and 4 days after corneal topical anti-inflammatory treatment with 0.2% dexamethasone. The expression of Substance P and its receptor NK-1R was also measured in the TG on day 4. RESULTS Corneal alkali burn induced leukocyte infiltration, including T cells, in the right TG at 4 and 8 days. In vivo MRI showed an increased contrast uptake in the right TG, which peaked at day 8. Prussian Blue(+) USPIO(+) macrophages were observed in the right TG and exhibited an M2 phenotype. The M2-macrophage infiltration was preponderant in the TG after damage. The proinflammatory cytokines Substance P and NK-1R were significantly increased in both the TGs. The expression of IL-1β and VEGF-A was significantly reduced in the right TG with dexamethasone treatment. CONCLUSIONS We suggest, for the first time, inflammatory involvement of brain structures following ocular surface damage. Our findings support the hypothesis that the neuropeptide Substance P may be involved in the propagation of inflammation from the cornea to the TG through corneal nerves.

VesselJ: A New Tool for Semiautomatic Measurement of Corneal Neovascularization.

PURPOSE To quantify blood and lymph angiogenesis in mouse corneal flat mounts by means of a novel plug-in for ImageJ, called VesselJ, based on a dynamic threshold algorithm. METHODS Corneal neovascularization (CNV) was induced in the right corneas of 20 C57BL6/N mice by means of alkali burn (n = 10) or intrastromal sutures (n = 10). All corneal flat mounts were stained for blood vessels with CD31 and for lymphatics with LYVE1. Three independent operators measured blood and lymphatic CNV with both a published manual method (mCNV) and VesselJ (automatic method; aCNV). RESULTS Both methods showed a strong reliability, defined as intraclass correlation coefficient (ICC) > 0.90, in quantifying hemangiogenesis for sutures and alkali burn. However, reliability of lymphatic mCNV varied from moderate in alkali burn (ICC: 0.700) to poor in sutures (ICC: 0.415), whereas it remained high in aCNV (alkali ICC: 0.996; sutures ICC: 0.959). Among sutures, a significant correlation between mCNV and aCNV was found among all the three operators for blood vessels and just for one operator for lymphatic vessels (P < 0.001). In the alkali burn model, correlation between blood mCNV and aCNV was significant for all operators after excluding three noisy flat mounts (P < 0.001), whereas no significant correlation was seen for lymphatic vessels. CONCLUSIONS VesselJ is a semiautomatic, reliable, and fast method to quantify corneal hem- and lymphangiogenesis in corneal flat mounts. VesselJ can be easily used in the sutures model; it should be applied to other models (e.g., alkali burn) only after checking for background hyperfluorescence. Italian Abstract.

Tumor necrosis factor-α inhibitors as a treatment of corneal hemangiogenesis and lymphangiogenesis.

Abstract: The cornea is normally devoid of blood and lymphatic vessels; however, a number of infectious/inflammatory diseases can induce corneal neovascularization (CNV). Tumor necrosis factor (TNF)-&agr;, a well known pro-inflammatory cytokine, acts on the vascular endothelium by promoting vasodilatation, edema, and leukocyte recruitment, which are all commonly associated with the development of CNV. Corneal neovascularization is the second cause of blindness worldwide; hence, pharmacological TNF-&agr; inhibition might represent an attractive therapeutic option. Although none of the existing TNF-&agr; antagonists has been registered as a CNV inhibitor, three of them (etanercept, adalimumab, and infliximab) have been proposed to control ocular inflammation. More specifically, it has been demonstrated that infliximab is also effective in reducing hemangiogenesis and lymphangiogenesis in different animal models of CNV. In this article, we review the role of TNF-&agr; on the ocular surface and, in particular, its specific role in the process of CNV. Moreover, we review existing literature and speculate on the potential role of TNF-&agr; inhibitors in the treatment of CNV.

Substance P and its Inhibition in Ocular Inflammation

Neuropeptides, and specifically Substance P (SP), can crucially contribute to the ocular inflammatory response. SP is an undecapeptide that is secreted from sensory nerve endings and from various immune cells during inflammation. SP modulates ocular inflammation through its binding with the high-affinity neurokinin-1 receptor (NK-1R). This receptor is expressed on nerves, immune cells, and epithelial cells. SP is a key mediator of neurogenic inflammation as it induces increased microvascular permeability, vasodilatation, plasma extravasation, and subsequent tissue edema. In addition, macrophages can release inflammatory mediators such as interleukins, chemokines, and growth factors in response to SP stimulation. Inhibition of SP activity, either through blockade of the neuropeptide release or the use of SP receptor antagonists, ameliorates ocular inflammation, it restores immune privilege and improves a number of clinical endpoints associated with inflammation, such as corneal opacity, ocular perforation, and angiogenesis. This review of the literature will summarize the role of SP in the ocular inflammatory response (with an emphasis on the ocular surface). In addition, it will review the therapeutic effects of SP blockade to control ocular inflammation (i) in animal models and (ii) in highly prevalent human diseases.

Quantifying Ocular Surface Inflammation and Correlating It With Inflammatory Cell Infiltration In Vivo: A Novel Method

PURPOSE The purpose of this study was to develop a novel, objective, and semiautomated method to quantify conjunctival redness by correlating measured redness with standard clinical redness and symptom scales and inflammatory cell infiltration. METHODS Eleven outpatients presenting with mild to severe conjunctival hyperemia were included in the study. Clinical examination included patient history; visual analogue score (VAS) for ocular symptoms; 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ 25) for quality of life/vision; photographs of the anterior segment graded for conjunctival hyperemia, using Efron, relative redness of image (RRI), and edge feature (EF) scales; and conjunctival impression cytology analyzed by flow cytometry. Differences between affected and unaffected eyes were evaluated, and correlations among questionnaire scores, ocular hyperemia grading scores, and assessment of biological markers were performed. RESULTS Visual analogue score (P < 0.0001), Efron scale (P = 0.0003), RRI scores (P = 0.0004), and EF scores (P < 0.0001) and the percentage of granulocytes (defined as cluster of differentiation [CD] 45dim; P = 0.0080) were significantly higher in affected eyes. Conversely, the percentage of CD45bright leukocytes was reduced in affected eyes (P = 0.0054). Both the RRIs and EFs were positively correlated with VAS, Efron scale, percentages of conjunctival granulocytes, and CD45brightCD3neg cells, whereas they were negatively correlated with the percentage of CD45brightCD3pos cells. Edge feature and RRI were correlated (Spearman r = 0.78, P < 0.0001). CONCLUSIONS Ocular redness is a cardinal sign driving clinical judgment in highly prevalent ocular disorders; hence, we suggest that our semiautomated and reproducible method may represent a helpful tool in the follow-up of these patients. Italian Abstract.

Angiopoietin 2 expression in the cornea and its control of corneal neovascularisation.

Purpose To define proangiogenic angiopoietin 2 (ANG2) expression and role(s) in human and mouse vascularised corneas. Further, to evaluate the effect of ANG2 inhibition on corneal neovascularisation (CNV). Methods CNV was induced in FVB mice by means of intrastromal suture placement. One group of animals was sacrificed 10 days later; corneas were immunostained for ANG2 and compared with (i) mouse non-vascularised corneas and (ii) human vascularised and non-vascularised corneas. A second group of CNV animals was treated systemically with an anti-ANG2 antibody. After 10 days, the corneas were whole-mounted, stained for CD31 and LYVE1 and lymphatic/blood vessels quantified. In another set of experiments, the corneal basal Bowman membrane was either (i) removed or (ii) left in place. After 2 or 10 days the corneas were removed and immunostained for collagen IV, ANG2, CD31, LYVE1, CD11b and MRC1 markers. Results In human beings and mice, ANG2 is expressed only in the epithelium, and, mildly, in the endothelium, of the avascular cornea. Instead, it is expressed in the epithelium, endothelium and stroma of vascularised corneas. Disruption of the Bowman membrane is associated with a significant increase of (i) ANG2 stromal expression and (ii) proangiogenic macrophage infiltration in the corneal stroma. Finally, blocking ANG2 significantly reduced hemangiogenesis, lymphangiogenesis and macrophage infiltration. Conclusions Balancing proper healing and good vision is crucial in the cornea, constantly exposed to potential injuries. In this paper, we suggest the existence of a mechanism regulating the onset of inflammation (and associated CNV) depending on injury severity.

Growth inhibition of formed corneal neovascularization following Fosaprepitant treatment

The aim of this study was to test the efficacy of Neurokinin‐1 Receptor (NK‐1R) antagonist −Fosaprepitant− in inducing regression of established corneal neovascularization (CNV).