Influence of format on in vitro penetration of antibody fragments through porcine cornea

Pharmacogenomic Analysis of Response to Topical Tumor Necrosis Factor α Antagonist Licaminlimab (OCS-02) in Dry Eye Disease [RETRACTED]

PURPOSE

The purpose of this study was to evaluate the pharmacogenomics of response to topical ocular tumor necrosis factor α (TNFα) inhibitor licaminlimab in patients with DED.

METHODS

Three single-nucleotide polymorphisms (SNPs) associated with Sjögren syndrome, 3 in the TNFα gene and 1 in the TNF receptor 1 (TNFR1) gene, were assessed for association with response to licaminlimab in participants from a randomized, vehicle-controlled, Phase 2 study in which adults with DED and severe ocular discomfort persisting despite treatment with artificial tears received licaminlimab or vehicle for 6 weeks. Response was assessed for change from baseline in Global Ocular Discomfort score at Day 29 of treatment. The pharmacogenomic analysis was a prospectively specified exploratory objective of the study. mRNA expression for TNFα, interleukin (IL) 1β, and IL8 in conjunctival epithelium cells was determined. The relationship between SNPs and response to licaminlimab was assessed using a mixed model repeated measures analysis.

RESULTS

SNP rs1800693 in the TNFR1 gene showed a significant effect on response to licaminlimab ( P < 0.0001, initial association test); no effect was seen for any of the other SNPs tested. The CC genotype of rs1800693 was associated with much greater response to licaminlimab than the CT or TT genotypes: LS mean changes from baseline to Day 29 in Global Ocular Discomfort score were -29.5, -0.09, and -3.90, in patients with the CC, CT, and TT genotypes, respectively ( P < 0.0001). No significant effect was observed in vehicle-treated patients. Improvements from baseline were seen in 3/4 licaminlimab-treated participants with the CC genotype. Conjunctival epithelium cell levels of mRNA for TNFα, IL1β, and IL8 decreased from baseline in participants with the CC genotype, but not with the CT or TT genotypes. Between-genotype differences in mRNA levels were not observed in participants receiving vehicle.

CONCLUSIONS

The CC genotype of rs1800693, relatively common in patients with DED, was strongly associated with response to licaminlimab and decreased inflammatory cytokine gene expression in ocular surface cells during treatment. This study is one of the first to our knowledge to investigate pharmacogenomics in the treatment of DED.

Safety and tolerability of pooled human immune globulins after topical ophthalmic administration in New Zealand White rabbits

PURPOSE

To evaluate the safety and tolerability of pooled human immune globulins, Flebogamma® 5% DIF and Flebogamma® 10% DIF, administered by topical ophthalmic instillation to New Zealand White (NZW) rabbits.

METHODS

Male NZW rabbits were used in this study. In the acute single dose tolerability study, rabbits (n = 12) received a single topical dose of Flebogamma® 5% DIF. In the two-week repeated-dose tolerability study, rabbits (n = 5 for each group) were administered either Flebogamma® 5% DIF or Flebogamma® 10% DIF by topical bilateral administration four times daily (q.i.d.) between 8 am and 6 pm for a period of two weeks. Full ophthalmic examinations were conducted to evaluate ocular tolerability at baseline, Day 7, and Day 14.

RESULTS

In the acute single dose study, mild hyperaemia was observed in 1 out of 4 eyes at each 4 h and 24 h post-instillation of Flebogamma® 5% DIF. In the repeated dose study, no ocular signs were detected after q.i.d. topical instillation of Flebogamma® 5% DIF, while Flebogamma® 10% DIF resulted in mild hyperaemia in 8 out of 10 eyes on Day 7, and 5 out of 10 eyes on Day 14. No positive corneal fluorescein staining was detected. Schirmer tear test results were unremarkable. No other ocular signs were observed. Administration of immune globulins had no effect on intraocular pressure.

CONCLUSIONS

Flebogamma® 5% DIF and Flebogamma® 10% DIF were well-tolerated by NZW rabbits following single and repeat dose topical ophthalmic administration, supporting the future development of topical pooled human immune globulins for the treatment of ocular surface disease.

Topical Solution for Retinal Delivery: Bevacizumab and Ranibizumab Eye Drops in Anti-Aggregation Formula (AAF) in Rabbits

PURPOSE

Wet age-related macular degeneration (AMD) is a blinding retinal disease. Monthly intravitreal anti-VEGF antibody injections of bevacizumab (off-label) and ranibizumab (FDA approved) are the standard of care. Antibody aggregation may interfere with ocular absorption/distribution. This study assessed topical delivery of dilute antibodies to the posterior segment of rabbit eyes using a novel anti-aggregation formula (AAF).

METHODS

Bevacizumab, or biosimilar ranibizumab was diluted to 5 mg/ml in AAF. All rabbits were dosed twice daily. Substudy 1 rabbits (bevacizumab, 100 µl eye drops): Group 1 (bevacizumab/AAF, n = 6); Group 2 (bevacizumab/PBS, n = 7) and Vehicle control (AAF, n = 1). Substudy 2 rabbits (ranibizumab biosimilar/AAF, 50 µl eye drops): (ranibizumab biosimilar/AAF, n = 8). At 14.5 days, serum was drawn from rabbits. Aqueous, vitreous and retina samples were recovered from eyes and placed into AAF aliquots. Tissue analyzed using AAF as diluent.

RESULTS

Bevacizumab in AAF permeated/accumulated in rabbit aqueous, vitreous and retina 10 times more, than when diluted in PBS. AAF/0.1% hyaluronic acid eye drops, dosed twice daily, provided mean tissue concentrations (ng/g) in retina (29.50), aqueous (12.34), vitreous (3.46), and serum (0.28 ng/ml). Additionally, the highest concentration (ng/g) of ranibizumab biosimilar was present in the retina (18.0), followed by aqueous (7.82) and vitreous (1.47). Serum concentration was negligible (< 0.04 ng/ml). No irritation was observed throughout the studies.

CONCLUSIONS

Bevacizumab and ranibizumab, in an AAF diluent eye drop, can be delivered to the retina, by the twice daily dosing of a low concentration mAb formulation. This may prove to be an adjunct to intravitreal injections.

Successful regression of newly formed corneal neovascularization by subconjunctival injection of bevacizumab in patients with chemical burns

Purpose

To investigate the effect and timing of subconjunctival bevacizumab injection on inhibiting corneal neovascularization (CorNV) in patients after chemical burns.

Methods

Patients with CorNV secondary to chemical burns were involved. Two subconjunctival injections of bevacizumab (2.5 mg/0.1 mL per involved quadrant) with an interval of 4 weeks were administered, and followed up a year. The area occupied by neovascular vessels (NA), accumulative neovascular length (NL), mean neovascular diameter (ND), best-corrected visual acuity (BCVA) and intraocular pressure (IOP) were evaluated. Complication was also recorded.

Results

Eleven patients with CorNV were involved. Eight patients had a history of surgery (four had amniotic grafts, one had keratoplasty, and three had amniotic grafts and keratoplasty). Decreasing in NA, NL, and ND were statistically significant at each time point compared to the baseline (p < 0.01). CorNV that developed within 1 month was considerably regressed, and vessels with fibrovascular membranes were found to be narrower and shorter than pretreatment. BCVA improved in five patients (from one to five lines), remained unchanged in five patients, and decreased in one patient compared to pretreatment.

Conclusion

Subconjunctival bevacizumab injection has a particular potential for the regression of CorNV, especially newly formed within 1 month in patients after chemical burns.

Topical Ocular Anti-TNFα Agent Licaminlimab in the Treatment of Acute Anterior Uveitis: A Randomized Phase II Pilot Study

Purpose

Licaminlimab is a new anti-TNFα antibody fragment for topical ocular application. This phase II study assessed the tolerability, treatment effect, and pharmacokinetics of licaminlimab in acute anterior uveitis (AAU).

Methods

In this multicenter, randomized, parallel-group, double-masked study, 43 adult patients with non-infectious AAU and Standardization of Uveitis Nomenclature (SUN) anterior chamber (AC) cell score of 2+ or 3+ were randomized (3:1 ratio) to licaminlimab (60 mg/mL, 8 drops/day for 15 days, 4 drops/day for 7 days, then matching vehicle for 7 days) or dexamethasone eye drops (8 drops/day for 15 days, tapering to 1 drop/day over 14 days). The primary efficacy end point was clinical response (≥2-step decrease in AC cell grade at day 15). A treatment effect was considered as established if the lower limit of the 95% posterior interval of the responder rate was >30%. Serum levels of licaminlimab were determined.

Results

The day 15 response rate for licaminlimab was 56%; the lower bound of the 95% credible interval was 40% (i.e. >30%), demonstrating a treatment effect according to prespecified criteria. By day 4, 36% of licaminlimab-treated patients were responders; 76% had an AC cell grade of 0 on ≥1 post-treatment visit. The day 15 dexamethasone response rate was 90% (no inferential between-arm comparison was planned). Both treatments were well-tolerated. Intraocular pressure increased from baseline with dexamethasone but not licaminlimab. Licaminlimab was undetectable in serum in most patients.

Conclusions

Licaminlimab is the first biologic demonstrated to have a treatment effect on an intraocular condition with topical ocular application. The trial met its primary objective and the observed responder rate for licaminlimab was 56.0%. Ocular administration of licaminlimab was well-tolerated in adult subjects with AAU for up to 35 days.

Pre-incubation of corneal donor tissue with sCD83 improves graft survival via the induction of alternatively activated macrophages and tolerogenic dendritic cells

Immune responses reflect a complex interplay of cellular and extracellular components which define the microenvironment of a tissue. Therefore, factors that locally influence the microenvironment and re-establish tolerance might be beneficial to mitigate immune-mediated reactions, including the rejection of a transplant. In this study, we demonstrate that pre-incubation of donor tissue with the immune modulator soluble CD83 (sCD83) significantly improves graft survival using a high-risk corneal transplantation model. The induction of tolerogenic mechanisms in graft recipients was achieved by a significant upregulation of Tgfb, Foxp3, Il27, and Il10 in the transplant and an increase of regulatory dendritic cells (DCs), macrophages (Mφ), and T cells (Tregs) in eye-draining lymph nodes. The presence of sCD83 during in vitro DC and Mφ generation directed these cells toward a tolerogenic phenotype leading to reduced proliferation-stimulating activity in MLRs. Mechanistically, sCD83 induced a tolerogenic Mφ and DC phenotype, which favors Treg induction and significantly increased transplant survival after adoptive cell transfer. Conclusively, pre-incubation of corneal grafts with sCD83 significantly prolongs graft survival by modulating recipient Mφ and DCs toward tolerance and thereby establishing a tolerogenic microenvironment. This functional strategy of donor graft pre-treatment paves the way for new therapeutic options in the field of transplantation.

Toward Drug-Like Multispecific Antibodies by Design

The success of antibody therapeutics is strongly influenced by their multifunctional nature that couples antigen recognition mediated by their variable regions with effector functions and half-life extension mediated by a subset of their constant regions. Nevertheless, the monospecific IgG format is not optimal for many therapeutic applications, and this has led to the design of a vast number of unique multispecific antibody formats that enable targeting of multiple antigens or multiple epitopes on the same antigen. Despite the diversity of these formats, a common challenge in generating multispecific antibodies is that they display suboptimal physical and chemical properties relative to conventional IgGs and are more difficult to develop into therapeutics. Here we review advances in the design and engineering of multispecific antibodies with drug-like properties, including favorable stability, solubility, viscosity, specificity and pharmacokinetic properties. We also highlight emerging experimental and computational methods for improving the next generation of multispecific antibodies, as well as their constituent antibody fragments, with natural IgG-like properties. Finally, we identify several outstanding challenges that need to be addressed to increase the success of multispecific antibodies in the clinic.

Topical Bevacizumab for the Treatment of Ocular Surface Squamous Neoplasia

PURPOSE

To determine the efficacy and safety of topical bevacizumab treatment in patients with ocular surface squamous neoplasia (OSSN).

METHODS

Six eyes of 6 patients with primary OSSN confirmed by impression cytology received topical 5 mg/mL bevacizumab 4 times daily for a period of 8 weeks. Patients were evaluated in 2-week intervals. Digital photography images were obtained at each visit and changes in the size of the lesions were analyzed by image analysis software.

RESULTS

The mean age of the patients was 66 ± 13 (± SD) years. Four tumors were nasal in origin and 2 tumors were temporal. The mean reduction observed in the lesion area was 43% ± 24.2% (range, 20%-71%) in the first month and 68% ± 29.7% (range, 42%-100%) in the second month when compared with the baseline area. Four patients required tumor excision at the end of the treatment period. Surgical treatment was not necessary in 2 patients due to complete disappearance of the tumor, which was confirmed by impression cytology. The visual acuity was stable in all patients and no systemic or visual side effects were observed during the study period.

CONCLUSIONS

Topical bevacizumab is effective as a neoadjuvant therapy combined with surgical excision for the treatment of OSSN. Topical bevacizumab may be used before surgery to decrease the size of the excision. Excision may be unnecessary in responsive patients.

Permeation of proteins, oligonucleotide and dextrans across ocular tissues: experimental studies and a literature update

Proteins and oligonucleotides represent powerful tools for the treatment of several ocular diseases, affecting both anterior and posterior eye segments. Despite the potential of these compounds, their administration remains a challenge. The last years have seen a growing interest for the noninvasive administration of macromolecular drugs, but still there is only little information of their permeability across the different ocular barriers. The aim of this work was to evaluate the permeation of macromolecules of different size, shape and charge across porcine ocular tissues such as the isolated sclera, the choroid Bruch's membrane and the cornea, both intact and de-epitelialized. Permeants used were two proteins (albumin and cytochrome C), an oligonucleotide, two dextrans (4 and 40 kDa) and a monoclonal antibody (bevacizumab). Obtained data and its comparison with the literature highlight the difficulties in predicting the behavior of macromolecules based on their physicochemical properties, because the interplay between the charge, molecular radius and conformation prevent their analysis separately. However, the data can be of great help for a rough evaluation of the feasibility of a noninvasive administration and for building computational models to improve understanding of the interplay among static, dynamic and metabolic barriers in the delivery of macromolecules to the eye.

Targeted localized use of therapeutic antibodies: a review of non-systemic, topical and oral applications

Therapeutic antibodies provide important tools in the "medicine chest" of today's clinician for the treatment of a range of disorders. Typically monoclonal or polyclonal antibodies are administered in large doses, either directly or indirectly into the circulation, via a systemic route which is well suited for disseminated ailments. Diseases confined within a specific localized tissue, however, may be treated more effectively and at reduced cost by a delivery system which targets directly the affected area. To explore the advantages of the local administration of antibodies, we reviewed current alternative, non-systemic delivery approaches which are in clinical use, being trialed or developed. These less conventional approaches comprise: (a) local injections, (b) topical and (c) peroral administration routes. Local delivery includes intra-ocular injections into the vitreal humor (i.e. Ranibizumab for age-related macular degeneration), subconjunctival injections (e.g. Bevacizumab for corneal neovascularization), intra-articular joint injections (i.e. anti-TNF alpha antibody for persistent inflammatory monoarthritis) and intratumoral or peritumoral injections (e.g. Ipilimumab for cancer). A range of other strategies, such as the local use of antibacterial antibodies, are also presented. Local injections of antibodies utilize doses which range from 1/10th to 1/100th of the required systemic dose therefore reducing both side-effects and treatment costs. In addition, any therapeutic antibody escaping from the local site of disease into the systemic circulation is immediately diluted within the large blood volume, further lowering the potential for unwanted effects. Needle-free topical application routes become an option when the condition is restricted locally to an external surface. The topical route may potentially be utilized in the form of eye drops for infections or corneal neovascularization or be applied to diseased skin for psoriasis, dermatitis, pyoderma gangrenosum, antibiotic resistant bacterial infections or ulcerated wounds. Diseases confined to the gastrointestinal tract can be targeted directly by applying antibody via the injection-free peroral route. The gastrointestinal tract is unusual in that its natural immuno-tolerant nature ensures the long-term safety of repeatedly ingesting heterologous antiserum or antibody materials. Without the stringent regulatory, purity and clean room requirements of manufacturing parenteral (injectable) antibodies, production costs are minimal, with the potential for more direct low-cost targeting of gastrointestinal diseases, especially with those caused by problematic antibiotic resistant or toxigenic bacteria (e.g. Clostridium difficile, Helicobacter pylori), viruses (e.g. rotavirus, norovirus) or inflammatory bowel disease (e.g. ulcerative colitis, Crohn's disease). Use of the oral route has previously been hindered by excessive antibody digestion within the gastrointestinal tract; however, this limitation may be overcome by intelligently applying one or more strategies (i.e. decoy proteins, masking therapeutic antibody cleavage sites, pH modulation, enzyme inhibition or encapsulation). These aspects are additionally discussed in this review and novel insights also provided. With the development of new applications via local injections, topical and peroral routes, it is envisaged that an extended range of ailments will increasingly fall within the clinical scope of therapeutic antibodies further expanding this market.

Pharmacokinetics of bevacizumab after topical and intravitreal administration in human eyes

Background

Topical bevacizumab is a potential treatment modality for corneal neovascularization, and several recent studies have demonstrated its efficacy. No previous study of the pharmacokinetics of topical bevacizumab has been performed in human eyes. The purpose of this study is to investigate the pharmacokinetics of topical administration of bevacizumab in human eyes, and also to compare the pharmacokinetics of intravitreal bevacizumab injections with previously reported data.

Methods

Twenty-two (22 eyes) were included in this study, and divided into four groups: eight patients received topical bevacizumab and aqueous samples were obtained 1 hour later during cataract extraction surgery (group 1), eight patients received topical bevacizumab and vitreous samples were obtained 1 day later during pars-plana vitrectomy (PPV) (group 2), three patients received intravitreal bevacizumab and vitreous samples were obtained during PPV (group 3). Vitreous samples from three patients who received no bevacizumab served as controls (group 4). All samples underwent enzyme-linked immunosorbent assay to detect bevacizumab.

Results

No bevacizumab was detected in the aqueous or vitreous of any topically treated eyes. The mean vitreal half-life for intravitreally injected bevacizumab was 4.9 days in four non-vitrectomized eyes and 0.66 days in one previously vitrectomized eye.

Conclusions

Topically administered bevacizumab does not penetrate the cornea into the anterior chamber and vitreous cavity, indicating that topical use for treating corneal neovascularization has minimal risk of intraocular penetration and adverse events related to intraocular vascular endothelial growth factor inhibition. The half-life following intravitreal bevacizumab injection measured in this study is comparable to that of previous reports, and includes the first demonstration of a significantly reduced half-life following intravitreal injection in a previously vitrectomized eye.

Topical application of soluble CD83 induces IDO-mediated immune modulation, increases Foxp3+ T cells, and prolongs allogeneic corneal graft survival

Modulation of immune responses is one of the main research aims in transplant immunology. In this study, we investigate the local immunomodulatory properties of soluble CD83 (sCD83) at the graft-host interface using the high-risk corneal transplantation model. In this model, which mimics the inflammatory status and the preexisting vascularization of high-risk patients undergoing corneal transplantation, allogeneic donor corneas are transplanted onto sCD83-treated recipient animals. This model allows the direct and precise application of the immune modulator at the transplantation side. Interestingly, sCD83 was able to prolong graft survival after systemic application as well as after topical application, which is therapeutically more relevant. The therapeutic effect was accompanied by an increase in the frequency of regulatory T cells and was mediated by the immune-regulatory enzyme IDO and TGF-β. In vitro, sCD83 induced long-term IDO expression in both conventional and plasmacytoid dendritic cells via autocrine or paracrine production of TGF-β, a cytokine previously shown to be an essential mediator of IDO-dependent, long-term tolerance. These findings open new treatment avenues for local immune modulation after organ and tissue transplantation.

Corneal neovascularization and the utility of topical VEGF inhibition: ranibizumab (Lucentis) vs bevacizumab (Avastin)

Corneal avascularity is necessary for the preservation of optimal vision. The cornea maintains a dynamic balance between pro- and antiangiogenic factors that allows it to remain avascular under normal homeostatic conditions; however, corneal avascularity can be compromised by pathologic conditions that negate the cornea's "angiogenic privilege." The clinical relevance of corneal neovascularization has long been recognized, but management of this condition has been hindered by a lack of safe and effective therapeutic modalities. Herein, the etiology, epidemiology, pathogenesis, and treatment of corneal neovascularization are reviewed. Additionally, the authors' recent findings regarding the clinical utility of topical ranibizumab (Lucentis®) and bevacizumab (Avastin®) in the treatment of corneal neovascularization are summarized. These findings clearly indicate that ranibizumab and bevacizumab are safe and effective treatments for corneal neovascularization when appropriate precautions are observed. Although direct comparisons are not conclusive, the results suggest that ranibizumab may be modestly superior to bevacizumab in terms of both onset of action and degree of efficacy. In order to justify the increased cost of ranibizumab, it will be necessary to demonstrate meaningful treatment superiority in a prospective, randomized, head-to-head comparison study.

3-hydroxykynurenine suppresses CD4+ T-cell proliferation, induces T-regulatory-cell development, and prolongs corneal allograft survival

PURPOSE

IDO (indoleamine 2,3-dioxygenase) modulates the immune response by depletion of the essential amino acid tryptophan, and IDO overexpression has been shown to prolong corneal allograft survival. This study was conducted to examine the effect of kynurenines, the products of tryptophan breakdown and known to act directly on T lymphocytes, on corneal graft survival.

METHODS

The effects of kynurenines on T-cell proliferation and death, T-regulatory-cell development, and dendritic cell function, phenotype, and viability were analyzed in vitro. The effect of topical and systemic administration of 3-hydroxykynurenine (3HK) on orthotopic murine corneal allograft survival was examined.

RESULTS

T-lymphocyte proliferation was inhibited by two of the four different kynurenines: 3HK and 3-hydroxyanthranilic acid (3HAA). This effect was accompanied by significant T-cell death. Neither 3HK nor 3HAA altered dendritic cell function, nor did they induce apoptosis or pathogenicity to corneal endothelial cells. Administration of systemic and topical 3HK to mice receiving a fully mismatched corneal graft resulted in significant prolongation of graft survival (median survival of control grafts, 12 days; of treated, 19 and 15 days, respectively; P < 0.0003). While systemic administration of 3HK was associated with a significant depletion of CD4(+) T, CD8(+) T, and B lymphocytes in peripheral blood, no depletion was found after topical administration.

CONCLUSIONS

The production of kynurenines, in particular 3HK and 3HAA, may be one mechanism (in addition to tryptophan depletion) by which IDO prolongs graft survival. These molecules have potential as specific agents for preventing allograft rejection in patients at high rejection risk.

Effects of rat anti-VEGF antibody in a rat model of corneal graft rejection by topical and subconjunctival routes

PURPOSE

To compare the effect of a rat anti-VEGF antibody, administered either by topical or subconjunctival (SC) routes, on a rat model of corneal transplant rejection.

METHODS

Twenty-four rats underwent corneal transplantation and were randomized into four treatment groups (n=6 in each group). G1 and G2 received six SC injections (0.02 ml 10 µg/ml) of denatured (G1) or active (G2) anti-VEGF from Day 0 to Day 21 every third day. G3 and G4 were instilled three times a day with denatured (G3) or active (G4) anti-VEGF drops (10 µg/ml) from Day 0 to Day 21. Corneal mean clinical scores (MCSs) of edema (E), transparency (T), and neovessels (nv) were recorded at Days 3, 9, 15, and 21. Quantification of neovessels was performed after lectin staining of vessels on flat mounted corneas.

RESULTS

Twenty-one days after surgery, MCSs differed significantly between G1 and G2, but not between G3 and G4, and the rejection rate was significantly reduced in rats receiving active antibodies regardless of the route of administration (G2=50%, G4=66.65% versus G1 and G3=100%; p<0.05). The mean surfaces of neovessels were significantly reduced in groups treated with active anti-VEGF (G2, G4). However, anti-VEGF therapy did not completely suppress corneal neovessels.

CONCLUSIONS

Specific rat anti-VEGF antibodies significantly reduced neovascularization and subsequent corneal graft rejection. The SC administration of the anti-VEGF antibody was more effective than topical instillation.

A novel protocol of whole mount electro-immunofluorescence staining

PURPOSE

To develop a new method of whole mount immunostaining that improves the penetration of staining reagents into the cornea and decreases non-specific binding and background.

METHODS

Adult mouse corneas were fixed overnight in 4% paraformaldehyde or a mixture of 4% paraformaldehyde and 0.2% glutaraldehyde in 0.1 M phosphate buffer, pH 7.4, at 4 degrees C. After washing with 0.1% Triton X-100, corneas were embedded in 1% solidified agarose in a plastic column and fluorescent staining reagents, e.g., FITC-IgG (Fluorescein isothiocyanate-immunoglobulinG) conjugates in 0.5% solidified agarose was overlaid onto the specimens. The column was directionally immersed in a submarine gel electrophoresis apparatus filled with Tris-glycine buffer (TGB, pH=7.4) and electrophoresed at 4-10 mA for 10-24 h. For comparison, conventional protocols of immune fluorescent staining were also employed. The outcomes were evaluated by confocal microscopy.

RESULTS

Antibody conjugates recognizing extracellular matrix (ECM) components, integral membrane protein, and intracellular structural proteins were used in whole mount corneas. The images of confocal laser scanning microscopy (CLSM) displayed a uniform distribution pattern of keratocan in corneal stroma, which is similar to that of section-staining. Anti-beta-tubulin antibodies bound to microtubes that are distributed within the whole cell body of superficial corneal epithelium cells and stromal keratocytes, but it was found perinuclear of corneal epithelial wing layers and endothelium; integral membrane protein, FAK (focal adhesion kinase), specifically labeled stromal cells of keratectomy corneas that healed for three weeks. In comparison, conventional protocols of immune fluorescent staining using the same antibody conjugates were also employed but did not yield satisfactory results. It was found that IgG conjugates examined did not readily penetrate into stroma and/or intact corneal epithelium. Phalloidin is a small molecule that can readily penetrate into deep tissue and preferentially binds to F-actin. After the whole mount electrofluorescent staining of phalloidin-rhodamine in the mouse cornea, the results were the same as conventional whole mount staining during the healing of epithelial debridement. The cytoplasmic protrusion formed by lamellipodia and filopodia can be clearly demonstrated.

CONCLUSIONS

These results indicate that the whole mount electro-immunofluorescent staining allows the detection of antigens in all layers of cornea, i.e., epithelium, stroma, and endothelium.

Single chain antibody fragments for ocular use produced at high levels in a commercial wheat variety

We are investigating the use of single chain antibody fragments (scFv) in eye drops for diagnosis and treatment of eye diseases. For ocular use, recombinant proteins must be free of bacterial endotoxin that causes inflammation in the eye. We required a means of generating high yields of scFvs with little endotoxin contamination. Using microprojectile bombardment we produced transgenic lines of the commercial wheat variety, Westonia, that express two scFvs that bind to CD4 or CD28 on the surface of rat thymocytes. A high level of expression of active scFv in the range 50-180 microg/g was measured by quantitative flow cytometry in crude extracts made from mature seeds. The levels of expression were stable over four generations of transgenic plants and mature seeds were stored for one year with little loss of scFv activity. Substantial purification of scFv was achieved by immobilised metal affinity chromatography. Compared to bacterial extracts, crude transgenic seed extracts contained only a small amount of endotoxin (150 EU/ml) that will be easily removed by purification. The transgenic wheat lines express functional scFv at levels comparable to production in bacteria and promise to be superior to bacteria for production of scFv pharmaceuticals for ocular use.