Characterization of a novel potency endpoint for the evaluation of immune checkpoint blockade in humanized mice

Introduction

Humanized mice are emerging as valuable models to experimentally evaluate the impact of different immunotherapeutics on the human immune system. These immunodeficient mice are engrafted with human cells or tissues, that then mimic the human immune system, offering an alternative and potentially more predictive preclinical model. Immunodeficient NSG mice engrafted with human CD34+ cord blood stem cells develop human T cells educated against murine MHC. However, autoimmune graft versus host disease (GvHD), mediated by T cells, typically develops 1 year post engraftment.

Methods

Here, we have used the development of GvHD in NSG mice, using donors with HLA alleles predisposed to autoimmunity (psoriasis) to weight in favor of GvHD, as an endpoint to evaluate the relative potency of monoclonal and BiSpecific antibodies targeting PD-1 and CTLA-4 to break immune tolerance.

Results

We found that treatment with either a combination of anti-PD-1 & anti-CTLA-4 mAbs or a quadrivalent anti-PD-1/CTLA-4 BiSpecific (MEDI8500), had enhanced potency compared to treatment with anti-PD-1 or anti-CTLA-4 monotherapies, increasing T cell activity both in vitro and in vivo. This resulted in accelerated development of GvHD and shorter survival of the humanized mice in these treatment groups commensurate with their on target activity.

Discussion

Our findings demonstrate the potential of humanized mouse models for preclinical evaluation of different immunotherapies and combinations, using acceleration of GvHD development as a surrogate of aggravated antigenic T-cell response against host.

Design and Efficacy of a Monovalent Bispecific PD-1/CTLA4 Antibody That Enhances CTLA4 Blockade on PD-1+ Activated T Cells

The clinical benefit of PD-1 blockade can be improved by combination with CTLA4 inhibition but is commensurate with significant immune-related adverse events suboptimally limiting the doses of anti-CTLA4 mAb that can be used. MEDI5752 is a monovalent bispecific antibody designed to suppress the PD-1 pathway and provide modulated CTLA4 inhibition favoring enhanced blockade on PD-1⁺ activated T cells. We show that MEDI5752 preferentially saturates CTLA4 on PD-1⁺ T cells versus PD-1^- T cells, reducing the dose required to elicit IL2 secretion. Unlike conventional PD-1/CTLA4 mAbs, MEDI5752 leads to the rapid internalization and degradation of PD-1. Moreover, we show that MEDI5752 preferentially localizes and accumulates in tumors providing enhanced activity when compared with a combination of mAbs targeting PD-1 and CTLA4 in vivo. Following treatment with MEDI5752, robust partial responses were observed in two patients with advanced solid tumors. MEDI5752 represents a novel immunotherapy engineered to preferentially inhibit CTLA4 on PD-1⁺ T cells. SIGNIFICANCE: The unique characteristics of MEDI5752 represent a novel immunotherapy engineered to direct CTLA4 inhibition to PD-1⁺ T cells with the potential for differentiated activity when compared with current conventional mAb combination strategies targeting PD-1 and CTLA4. This molecule therefore represents a step forward in the rational design of cancer immunotherapy.See related commentary by Burton and Tawbi, p. 1008.This article is highlighted in the In This Issue feature, p. 995.

Oncolytic Newcastle disease virus activation of the innate immune response and priming of antitumor adaptive responses in vitro

Oncolytic virus (OV) therapy is an emerging approach with the potential to redefine treatment options across a range of cancer indications and in patients who remain resistant to existing standards of care, including immuno-oncology (IO) drugs. MEDI5395, a recombinant Newcastle disease virus (NDV), engineered to express granulocyte–macrophage colony-stimulating factor (GM-CSF), exhibits potent oncolytic activity. It was hypothesized that activation of immune cells by MEDI5395, coupled with its oncolytic activity, would enhance the priming of antitumor immunity. Using MEDI5395 and recombinant NDVs encoding fluorescent reporter genes, we demonstrated preferential virus uptake and non-productive infection in myeloid cells, including monocytes, macrophages, and dendritic cells (DCs). Infection resulted in immune-cell activation, with upregulation of cell surface activation markers (e.g., CD80, PD-L1, HLA-DR) and secretion of proinflammatory cytokines (IFN-α2a, IL-6, IL-8, TNF-α). Interestingly, in vitro M2-polarized macrophages were more permissive to virus infection than were M1-polarized macrophages. In a co-culture system, infected myeloid cells were effective virus vectors and mediated the transfer of infectious NDV particles to tumor cells, resulting in cell death. Furthermore, NDV-infected DCs stimulated greater proliferation of allogeneic T cells than uninfected DCs. Antigens released after NDV-induced tumor cell lysis were cross-presented by DCs and drove activation of tumor antigen-specific autologous T cells. MEDI5395 therefore exhibited potent immunostimulatory activity and an ability to enhance antigen-specific T-cell priming. This, coupled with its tumor-selective oncolytic capacity, underscores the promise of MEDI5395 as a multimodal therapeutic, with potential to both enhance current responding patient populations and elicit de novo responses in resistant patients.

Intratumoral immunotherapy with TLR7/8 agonist MEDI9197 modulates the tumor microenvironment leading to enhanced activity when combined with other immunotherapies

Background

Immune checkpoint blockade (ICB) promotes adaptive immunity and tumor regression in some cancer patients. However, in patients with immunologically “cold” tumors, tumor-resident innate immune cell activation may be required to prime an adaptive immune response and so exploit the full potential of ICB. Whilst Toll-like receptor (TLR) agonists have been used topically to successfully treat some superficial skin tumors, systemic TLR agonists have not been well-tolerated.

Methods

The response of human immune cells to TLR7 and 8 agonism was measured in primary human immune cell assays. MEDI9197 (3M-052) was designed as a novel lipophilic TLR7/8 agonist that is retained at the injection site, limiting systemic exposure. Retention of the TLR7/8 agonist at the site of injection was demonstrated using quantitative whole-body autoradiography, HPLC-UV, and MALDI mass spectrometry imaging. Pharmacodynamic changes on T cells from TLR7/8 agonist treated B16-OVA tumors was assessed by histology, quantitative real time PCR, and flow cytometry. Combination activity of TLR7/8 agonism with immunotherapies was assessed in vitro by human DC-T cell MLR assay, and in vivo using multiple syngeneic mouse tumor models.

Results

Targeting both TLR7 and 8 triggers an innate and adaptive immune response in primary human immune cells, exemplified by secretion of IFNα, IL-12 and IFNγ. In contrast, a STING or a TLR9 agonist primarily induces release of IFNα. We demonstrate that the TLR7/8 agonist, MEDI9197, is retained at the sight of injection with limited systemic exposure. This localized TLR7/8 agonism leads to Th1 polarization, enrichment and activation of natural killer (NK) and CD8⁺ T cells, and inhibition of tumor growth in multiple syngeneic models. The anti-tumor activity of this TLR7/8 agonist is enhanced when combined with T cell-targeted immunotherapies in pre-clinical models.

Conclusion

Localized TLR7/8 agonism can enhance recruitment and activation of immune cells in tumors and polarize anti-tumor immunity towards a Th1 response. Moreover, we demonstrate that the anti-tumor effects of this TLR7/8 agonist can be enhanced through combination with checkpoint inhibitors and co-stimulatory agonists.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0724-8) contains supplementary material, which is available to authorized users.

Dendritic Cell-Derived TSLP Negatively Regulates HIF-1α and IL-1β During Dectin-1 Signaling

Thymic stromal lymphopoietin (TSLP) is a functionally pleotropic cytokine important in immune regulation, and TSLP dysregulation is associated with numerous diseases. TSLP is produced by many cell types, but has predominantly been characterized as a secreted factor from epithelial cells which activates dendritic cells (DC) that subsequently prime T helper (T_H) 2 immunity. However, DC themselves make significant amounts of TSLP in response to microbial products, but the functional role of DC-derived TSLP remains unclear. We show that TSLPR signaling negatively regulates IL-1β production during dectin-1 stimulation of human DC. This regulatory mechanism functions by dampening Syk phosphorylation and is mediated via NADPH oxidase-derived ROS, HIF-1α and pro-IL-1β expression. Considering the profound effect TSLPR signaling has on the metabolic status and the secretome of dectin-1 stimulated DC, these data suggest that autocrine TSLPR signaling could have a fundamental role in modulating immunological effector responses at sites removed from epithelial cell production of TSLP.

β-Glucan Size Controls Dectin-1-Mediated Immune Responses in Human Dendritic Cells by Regulating IL-1β Production

Dectin-1/CLEC7A is a pattern recognition receptor that recognizes β-1,3 glucans, and its stimulation initiates signaling events characterized by the production of inflammatory cytokines from human dendritic cells (DCs) required for antifungal immunity. β-glucans differ greatly in size, structure, and ability to activate effector immune responses from DC; as such, small particulate β-glucans are thought to be poor activators of innate immunity. We show that β-glucan particle size is a critical factor contributing to the secretion of cytokines from human DC; large β-glucan-stimulated DC generate significantly more IL-1β, IL-6, and IL-23 compared to those stimulated with the smaller β-glucans. In marked contrast, the secretion of TSLP and CCL22 were found to be insensitive to β-glucan particle size. Furthermore, we show that the capacity to induce phagocytosis, and the relative IL-1β production determined by β-glucan size, regulates the composition of the cytokine milieu generated from DC. This suggests that β-glucan particle size is critically important in orchestrating the nature of the immune response to fungi.

Developing in vitro expanded CD45RA+ regulatory T cells as an adoptive cell therapy for Crohn's disease

BACKGROUND AND AIM

Thymus-derived regulatory T cells (Tregs) mediate dominant peripheral tolerance and treat experimental colitis. Tregs can be expanded from patient blood and were safely used in recent phase 1 studies in graft versus host disease and type 1 diabetes. Treg cell therapy is also conceptually attractive for Crohn's disease (CD). However, barriers exist to this approach. The stability of Tregs expanded from Crohn's blood is unknown. The potential for adoptively transferred Tregs to express interleukin-17 and exacerbate Crohn's lesions is of concern. Mucosal T cells are resistant to Treg-mediated suppression in active CD. The capacity for expanded Tregs to home to gut and lymphoid tissue is unknown.

METHODS

To define the optimum population for Treg cell therapy in CD, CD4(+)CD25(+)CD127(lo)CD45RA(+) and CD4(+)CD25(+)CD127(lo)CD45RA(-) Treg subsets were isolated from patients' blood and expanded in vitro using a workflow that can be readily transferred to a good manufacturing practice background.

RESULTS

Tregs can be expanded from the blood of patients with CD to potential target dose within 22-24 days. Expanded CD45RA(+) Tregs have an epigenetically stable FOXP3 locus and do not convert to a Th17 phenotype in vitro, in contrast to CD45RA(-) Tregs. CD45RA(+) Tregs highly express α4β7 integrin, CD62L and CC motif receptor 7 (CCR7). CD45RA(+) Tregs also home to human small bowel in a C.B-17 severe combined immune deficiency (SCID) xenotransplant model. Importantly, in vitro expansion enhances the suppressive ability of CD45RA(+) Tregs. These cells also suppress activation of lamina propria and mesenteric lymph node lymphocytes isolated from inflamed Crohn's mucosa.

CONCLUSIONS

CD4(+)CD25(+)CD127(lo)CD45RA(+) Tregs may be the most appropriate population from which to expand Tregs for autologous Treg therapy for CD, paving the way for future clinical trials.

IRE1α mediates PKR activation in response to Chlamydia trachomatis infection

Protein kinase RNA activated (PKR) is a crucial mediator of anti-viral responses but is reported to be activated by multiple non-viral stimuli. However, mechanisms underlying PKR activation, particularly in response to bacterial infection, remain poorly understood. We have investigated mechanisms of PKR activation in human primary monocyte-derived dendritic cells in response to infection by Chlamydia trachomatis. Infection resulted in potent activation of PKR that was dependent on TLR4 and MyD88 signalling. NADPH oxidase was dispensable for activation of PKR as cells from chronic granulomatous disease (CGD) patients, or mice that lack NADPH oxidase activity, had equivalent or elevated PKR activation. Significantly, stimulation of cells with endoplasmic reticulum (ER) stress-inducing agents resulted in potent activation of PKR that was blocked by an inhibitor of IRE1α RNAse activity. Crucially, infection resulted in robust IRE1α RNAse activity that was dependent on TLR4 signalling and inhibition of IRE1α RNAse activity prevented PKR activation. Finally, we demonstrate that TLR4/IRE1α mediated PKR activation is required for the enhancement of interferon-β production following C. trachomatis infection. Thus, we provide evidence of a novel mechanism of PKR activation requiring ER stress signalling that occurs as a consequence of TLR4 stimulation during bacterial infection and contributes to inflammatory responses.

TSLP production by dendritic cells is modulated by IL-1β and components of the endoplasmic reticulum stress response

Thymic stromal lymphopoietin (TSLP) produced by epithelial cells acts on dendritic cells (DCs) to drive differentiation of T_H2‐cells, and is therefore important in allergic disease pathogenesis. However, DCs themselves make significant amounts of TSLP in response to microbial products, but little is known about the key downstream signals that induce and modulate this TSLP secretion from human DCs. We show that human monocyte derived DC (mDC) secretion of TSLP in response to Candida albicans and β‐glucans requires dectin‐1, Syk, NF‐κB, and p38 MAPK signaling. In addition, TSLP production by mDCs is greatly enhanced by IL‐1β, but not TNF‐α, in contrast to epithelial cells. Furthermore, TSLP secretion is significantly increased by signals emanating from the endoplasmic reticulum (ER) stress response, specifically the unfolded protein response sensors, inositol‐requiring transmembrane kinase/endonuclease 1 and protein kinase R‐like ER kinase, which are activated by dectin‐1 stimulation. Thus, TSLP production by mDCs requires the integration of signals from dectin‐1, the IL‐1 receptor, and ER stress signaling pathways. Autocrine TSLP production is likely to play a role in mDC‐controlled immune responses at sites removed from epithelial cell production of the cytokine, such as lymphoid tissue.

A fast system for reporting the Farnsworth-Munsell 100-hue colour vision test

We have developed a system for rapidly reporting the Farnsworth-Munsell (FM) 100-hue test using a personal computer and a bar code scanner. The computer generated report duplicates the conventional manual report of the FM 100-hue test so is very familiar to ophthalmologists and optometrists. The new system has proved to be of great assistance both in saving time and in eliminating arithmetic errors in the scoring calculations. The scanner technique produces two reports, one for each eye, within 4 min of the patient completing the test. This compares with the 60 min required by the conventional manual reporting system. In addition, it also gives a statistical analysis of the results in accordance with Verriest norms. The program is very versatile and user friendly, achieving a standard not present in the other FM 100-hue computerised systems currently available. As a consequence it makes this valuable diagnostic test much more accessible to patients and clinicians.

What patients want to know before they have cataract surgery

AIMS

To investigate what patients want to know before undergoing cataract surgery.

METHODS

A written questionnaire was answered by 190 patients prior to cataract surgery.

RESULTS

The five pieces of preoperative information rated most important were: chance of visual improvement; when vision would improve; overall risk of losing vision from the operation; effect of not having the operation, and the types of serious complications. When asked "should you be warned of a serious complication if it has a risk of happening", 93.5% said yes to a risk of 1 in 50 and 62.4% to 1 in 1000. Written information was requested by 85.7%. There were few differences between the sexes, and between those having their first or second operation.

CONCLUSIONS

Patients most wanted to know benefits and risks, even very small risks. Written information should be provided to ensure coverage and reinforce verbal information.

A comparison of two patient-friendly ERG electrodes

The ideal electroretinography (ERG) electrode does not exist. In deciding which electrode should be used in clinical practice the capacity to provide reproducible waveforms, maximal amplitudes and minimal irritation to the patient's eyes are the most important characteristics. This study tested two patient friendly electrodes, the gold foil (CH Electrodes, UK) and the H-K loop (Avanta, Slovenia). Seventeen normal volunteers were subjected to three standard measurements namely flash ERGs under photopic and scotopic conditions and the transient pattern ERG (PERG). Each test followed the guidelines set by the International Society for Clinical Electrophysiology of Vision (ISCEV). It was found that the mean values of the flash ERG a and b wave amplitudes and the PERG P50 and N95 amplitudes from the gold foil electrodes were approximately a factor of two larger than those from the H-K loop. In addition most of the subjects (13/17) felt less discomfort with the gold foil electrodes. We reached the conclusion that gold foil electrodes are the electrode of choice because they provide good patient comfort, reasonably high amplitudes and relatively reproducible results.

Predicting the refractive outcome after cataract surgery: the comparison of different IOLs and SRK-II v SRK-T

AIM

To determine any differences between the predictive abilities of the IOL calculation formulas of SRK-II and SRK-T and to compare these using two different IOL types.

METHODS

A prospective, consecutive, single surgeon clinical trial was conducted on 400 consecutive patients who received routine, standardised phacoemulsification cataract surgery. 200 had cataract surgery and had the Alcon MZ30BD, a 5.5 mm one piece PMMA IOL, and another 200 cases used the Chiron C11UB, a silicone plate haptic IOL. The data used optimised A-constants. The measures were preoperative axial length and keratometry, IOL implanted, and refractive error at 4-6 weeks postoperatively.

RESULTS

There was no significant difference between the predictive abilities of SRK-II or SRK-T. For the Alcon and Chiron lens respectively, prediction errors using SRK-II were <0.5 dioptres in 58% and 70% and for <1.0 dioptres in 84% and 92%. These differences were statistically significant (chi(2), p=0.02).

CONCLUSION

There are differences in the predictability of refractive outcomes between intraocular lens styles.

Chiral Ansa metallocenes with Cp ring-fused to thiophenes and pyrroles: syntheses, crystal structures, and isotactic polypropylene catalysts

Syntheses, crystal structures, and polymerization data for new isospecific metallocenes (heterocenes) having cyclopentenyl ligands b-fused to substituted thiophenes (Tp) and pyrroles (Pyr) are reported. The C2- and C1-symmetric heterocenes are dimethylsilyl bridged, have methyl groups adjacent to the bridgehead carbon atoms, and have aryl substituents protruding in the front. rac-Me2Si(2,5-Me2-3-Ph-6-Cp[b]Tp)2ZrCl2/MAO (MAO = methyl alumoxanes) is the most active metallocene catalyst for polypropylene reported to date. rac-Me2Si(2,5-Me2-3-Ph-6-Cp[b]Tp)2ZrCl2 and rac-Me2Si(2,5-Me2-1-Ph-4-Cp[b]Pyr)2ZrCl2 have the same structure, and the former is 6 times more active, produces half the total enantiofacial errors, and is 3.5 times less regiospecific in propylene polymerizations at the same conditions. rac-Me2Si(2-Me-4-Ph-1-Ind)2ZrCl2/MAO is 3.5 times lower in activity than rac-Me2Si(2,5-Me2-3-Ph-6-Cp[b]Tp)2ZrCl2 catalyst, and while the former is the more stereospecific and the less regiospecific, the sum of these two enantioface errors is the same for both species. Fine-tuning the heterocene sterics by changing selected hydrogen atoms on the ligands to methyl groups influenced their catalyst activities, stereospecificites, regiospecificites, and isotactic polypropylene (IPP) Mw. Thus, both substituting a hydrogen atom adjacent to the phenyl ring with a methyl group on an azapentalenyl ligand system and replacing one and then two hydrogens on the phenyl ring with methyls on thiopentalenyl ligands provided increased polymer Tm and Mw with increasing ligand bulk. Polymer molecular weights are sensitive to and inversely proportional to MAO concentration, and the catalyst activities increase when hydrogen is added for molecular weight control. The polymer Tm values with the thiopentalenyls as TIBAL/[Ph3C][B(C6F5)4] systems were higher than with MAO as catalyst activator. A racemic C1, pseudo-meso complex with a hybrid dimethylsilyl-bridged 2-Me-4-Ph-1-Ind/2,5-Me2-4-Ph-1-Cp[b]Pyr ligand produced the first sample of IPP with all the steric pentad intensities fitting the enantiomorphic site control model. Speculative mechanistic considerations are offered regarding electronic effects of the heteroatoms and steric effects of the ligand structures, the preferred phenyl torsion angles, and anion effects.

The early complications of cataract surgery: is routine review of patients 1 week after cataract extraction necessary?

OBJECTIVE

This study sought to define the nature and frequency of complications present 1 week after cataract surgery, to determine whether these complications are predictable, and to ascertain if patients undergoing cataract surgery require routine review at this time.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

One thousand consecutive patients undergoing cataract removal by either phacoemulsification or extracapsular extraction at a large teaching hospital between January 1996 and May 1998. Patients with both complicated and uncomplicated histories and surgeries were included.

MAIN OUTCOME MEASURES

Nature and frequency of complications present 1 week after cataract surgery.

RESULTS

At the routine 1-week visit, postoperative complications were observed in 41 of 1000 patients (4.1%). Twenty-one (51%) of these patients had a completely unremarkable history to that point, and whereas only four (19%) were symptomatic, 20 (95%) required a change to their postoperative management. The most significant unexpected complications were uveitis (seven cases), cystoid macular edema (four cases), and vitreous to the wound, exposed knots, and loose suture (one case of each). Complications were present in 20 of 257 (7.8%) patients with a preoperative or surgical risk factor, and there was a significant relationship between preoperative (P = 0.02), and combined preoperative and intraoperative risk factors (P = 0.001), and complications present at the 1-week review. The relationship between surgical risk factors and 1-week complications was not significant (P = 0.07). There were coexistent pathologic features in 19% of all eyes. Registrars performed 38% of surgeries, and 96% of cataracts were removed by phacoemulsification. Operative complications occurred in 6.7% of patients, most commonly a posterior capsule tear (4.4% of all cases). Complications were observed in 10% of eyes on the first postoperative day. Raised intraocular pressure was the complication in 88% of these patients.

CONCLUSIONS

This study provides an overview of modern cataract surgery in a large teaching hospital and indicates that abandonment of routine 1-week review may result in the failure to detect significant postoperative complications.

Cyanoacrylate glue for corneal perforations: a description of a surgical technique and a review of the literature

The effective early application of a cyanoacrylate glue corneal patch can aid in the management of small corneal perforations, corneal melts and wound leaks. Their use gives improved visual outcomes with reduced enucleation rates (6% vs 19%). It may also avoid the need for tectonic penetrating keratoplasty. Cyanoacrylate glue prevents re-epithelialization into the zone of damaged and naked stroma and prevents the development of the critical setting for collagenase production that leads to stromal melting. Cyanoacrylates also have significant bacteriostatic activity against gram-positive organisms. We describe a simple and easily reproducible method of cyanoacrylate corneal patch application, with neglible risk of inadvertent glue complications. It has the further advantage of a smooth corneal surface rather than an irregular surface as often occurs with direct application methods. With corneal application, the major concern is toxicity of cyanoacrylates through direct contact with the corneal endothelium and lens. Fibrin glues may be less toxic; however, they are not as readily available. The longer alkyl chains of currently available cyanoacrylate glues (e.g. Histoacryl) slows degradation significantly, limiting accumulation of histotoxic by-products to amounts that can be effectively eliminated by tissues. Vigilance in monitoring for infection/corneal infiltrate is necessary at all times, especially when the glue has been present for more than 6 weeks. Corneal patching with cyanoacrylate glue is a temporizing procedure only, buying time to allow healing secondary to medical treatment of the underlying condition, or allowing surgery to be elective and under more optimal conditions once inflammation has been reduced and the integrity of the globe restored.

Warfarin therapy and cataract surgery

PURPOSE

Cataract extraction in the warfarinized patient poses special considerations. Warfarin will increase the haemorrhagic risk but, more importantly, cessation or reduction in anticoagulation may well lead to serious thromboembolic phenomena. The purpose of this study was to assess the impact that warfarinization has on cataract extraction.

METHODS

One thousand consecutive cataract extractions performed at Christchurch Hospital between 1996 and 1998 were reviewed. Twenty-eight patients (29 eyes) were on warfarin. Reasons for anticoagulation, modification to treatment regimen and postoperative outcome measures were available for 23 eyes or 79% of the study population.

RESULTS

The preoperative international normalized ratio (INR) ranged from 1.00 to 2.40+/-0.37 with a mean of 1.52. No thromboembolic phenomena occurred and four minor perioperative haemorrhages were noted, none of which affected the final visual outcome.

CONCLUSIONS

If warfarin is required to counteract serious thromboembolic tendencies, then it should not be ceased perioperatively. The small numbers of perioperative haemorrhages that did occur were not visually significant.

Visual, refractive, and subjective outcomes after photorefractive keratectomy for myopia of 6 to 10 diopters using the Nidek laser

PURPOSE

To analyze the results of photorefractive keratectomy (PRK) for myopia of 6.0 to 10.0 diopters (D) using the Nidek laser and compare them with those in other series, including LASIK, and to analyze the subjective aspects of vision.

SETTING

Remuera Eye Clinic, Auckland, New Zealand.

METHOD

One hundred ninety-two eyes of 162 consecutive PRK patients with a 6 month follow-up were studied. All had myopia in the range of 6.0 to 10.0 D by spherical equivalent. Astigmatism of up to 3.5 D was treated by laser simultaneously. At 6 months, uncorrected visual acuity, best spectacle-corrected visual acuity, residual refractive error, and corneal haze were recorded. After the 6 month examination, a questionnaire was sent to all patients.

RESULTS

Uncorrected visual acuity of 20/20 was achieved in 59% of eyes and of 20/40 or better in 94%. The accuracy of correction was +/- 0.5 D of emmetropia in 77% and +/- 1.0 D in 94%. In 2 eyes (1.0%), corneal haze was assessed as 2+ and 2 Snellen lines of best corrected visual acuity were lost. The questionnaire revealed that 45% of patients had difficulties with night vision. This was better than before surgery in 35% but worse in 31%. Halos were seen around lights by 52%, but these were less than before surgery in 21% and worse in 26%. There was undue sensitivity to glare in 29%, but this was better than before surgery in 19% and worse in 28%. The overall quality of vision was better than before surgery in 60% and worse in 17%. Seventy-seven percent did not need spectacles. Ninety-eight percent said they would have the surgery again.

CONCLUSIONS

As long as the patients are informed of the limitations of PRK for myopia, the results are acceptable.

Primary choroidal malignant melanoma occurring in a New Zealand Maori

PURPOSE/METHOD

A case of a 28-year-old Maori with an aggressive primary choroidal malignant melanoma is presented.

RESULTS/CONCLUSION

Melanoma and particularly intra-ocular melanoma is very rare in pigmented races. This is the first reported case in the Maori.

Intermediate filament expression by normal and diseased human corneal epithelium

Cicatricial conjunctivitis may be a sequel to systemic disorders (eg, Stevens-Johnson syndrome, cicatricial pemphigoid) or local disorders such as chemical burns. The cicatrisation is often associated with corneal epithelial changes that cause visual loss. These have been attributed to encroachment of the conjunctival epithelium over the cornea. However, the epithelial anomalies are poorly understood. We investigated the corneal epithelial changes in cicatricial conjunctivitis with an immunohistochemical study of intermediate filaments in normal and pathological specimens. Our results show that the normal corneal epithelium is immunoreactive for cytokeratin 3 (CK 3) but not cytokeratin 19 (CK 19), whereas normal conjunctival epithelium is CK 3 negative and CK 19 positive. Conjunctiva artificially transposed over the cornea (after therapeutic conjunctival flap reconstruction) retained the normal pattern of conjunctival cytokeratin expression (CK 3 negative, CK 19 positive). Conversely, the entire corneal epithelium exhibited the normal cytokeratin pattern (CK 3 positive, CK 19 negative) in 82% of Stevens-Johnson, 80% of cicatricial pemphigoid, and 69% of chemical burns specimens. The findings suggest that conjunctival encroachment is not responsible for the changes at the corneal surface in cicatricial conjunctivitis and that the abnormal corneal epithelium is derived from native corneal cells in these diseases.

Intraocular lens materials and styles: a review

Biomaterial science has lead to the development of a variety of foldable intraocular lens (IOL) biomaterials. This literature review examines these lenses from both a basic science and a clinical perspective. By most parameters, hydrogel, soft acrylic and silicone IOL are better than polymethylmethacrylate (PMMA) lenses. Plate haptic silicone IOL have the lowest incidence of cystoid macula oedema and posterior capsule opacification, but these lenses require an intact anterior capsularhexis and posterior capsule. Yttrium aluminium garnet (YAG) laser capsulotomy must be delayed at least 3 months to avoid posterior lens dislocation. Silicone has the lowest threshold for YAG laser damage of all IOL materials and also adheres irreversibly to silicone oil with subsequent optical impairment. Three piece silicone IOL with polypropylene haptics have a higher incidence of decentration, pigment adherence and capsule opacification compared with PMMA haptics. Hydrogel lenses are very biocompatible and resistant to YAG laser damage, but pigment adheres to the surface more readily than PMMA. Soft acrylic IOL unfold slowly, resulting in controlled insertion, but it is possible to crack the lens and some lenses develop glistenings due to water accumulation. There are significant socioeconomic implications to the large differences in posterior capsule opacification rates between the various biomaterials and the lens styles.

Conjunctival fibrosis in ocular cicatricial pemphigoid--the role of cytokines

Ocular cicatricial pemphigoid (OCP) is a systemic, autoimmune disease characterised by conjunctival scarring that is often progressive. The pathophysiology of the fibrosis is unknown. This study aimed to determine which fibrogenic cytokines are present in the conjunctiva in patients with acute and chronic OCP as a first stage in determining the mechanisms of fibrosis. Conjunctival biopsies from patients with acute, subacute and chronic OCP (n=13) were compared to normal conjunctiva (n=10). Production of mRNA for, and expression of, transforming growth-beta1, 2 and 3 (TGF-beta), TGF-beta receptor, platelet derived growth factor (PDGF) and fibroblast growth factor (FGF) were assessed using in situ hybridisation and immunohistochemistry. Acute disease showed increased levels of mRNA for TGF-beta1 and 3, mainly in stromal fibroblasts and macrophages. In the stroma, there were concordant increases in latent and activated TGF-beta1 and 3 and TGF-beta receptor expression by fibroblasts. There were no significant increases in the expression of TGF-beta2, PDGF or FGF in acute disease. No cytokines or receptors were significantly increased in chronic disease. Acutely inflamed conjunctiva in OCP is associated with significant stromal levels of TGF-beta1 and 3 but not PDGF or FGF and none were increased in chronic disease. This suggests that TGF-beta may have a key role in the pathogenesis of the fibrosis. The absence of fibrogenic cytokines in chronic progressive OCP provides support for the proposal that fibroblasts in OCP conjunctiva may remain functionally and morphologically abnormal after the withdrawal of cytokine influences.

Acute ocular methanol toxicity: clinical and electrophysiological features

PURPOSE

The present report describes previously undocumented changes in the electroretinogram (ERG) and visual-evoked response (VER) following acute methanol ingestion and highlights the ocular effects of methanol poisoning.

METHODS

Two cases of acute ocular damage following methanol ingestion are presented. One patient underwent extensive electrophysiological and psychophysical testing.

RESULTS

Both patients reported transient visual disturbances. In each patient vision was 6/6 in both eyes at presentation but subsequently improved to 6/4. Colour vision (Ishihara plates) and pupillary reactions were normal. The optic discs were hyperaemic and swollen and retinal oedema extended along the major vascular arcades. There was cystoid macular oedema and 'pseudo cherry red spots' were observed. Automated field analysis revealed a generalized depression of retinal sensitivity, an enlargement of one blind spot and paracentral scotomas. The scotopic ERG was subnormal with diminished a- and b-waveforms and the cone response to flicker was reduced. The pattern VER P2 waveform was normal in latency but decreased in amplitude.

CONCLUSIONS

Acute methanol ingestion can cause characteristic ocular damage, together with widespread electrophysiological dysfunction. The data presented suggest that methanol affects the photoreceptors, Muller cells and the retrolaminar portion of the optic nerve.

A method for separation and staining of flat mounts of human corneal endothelium

A technique is described in which sheets of corneal endothelium are removed from human donor corneo-scleral discs. Celloidin solution was applied to the endothelial surface, allowed to dry, peeled off with the attached endothelial cell layer and mounted on a glass slide. Following removal of the celloidin with acetone, this endothelial cell flat mount was then stained with H&E and monoclonal antibodies to cell adhesion molecules. A pilot study of endothelial cell adhesion molecule expression in flat mount preparations of 14 corneas showed constitutive neural cell adhesion molecule (NCAM) expression, but a lower degree of focal expression of intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VACM)-1, P/E-selectin and HLA-DR.

Anatomy and physiology of eyelash follicles: relevance to lash ablation procedures

BACKGROUND

This study aimed to define the anatomy of the eyelash follicles in order to improve methods of selective lash ablation.

MATERIALS AND METHODS

Dimensions of eyelash follicles were determined from histological specimens of the upper and lower lids of 10 patients. For one of these patients, the eyelash follicles were categorized as quiescent or actively growing, according to standard hair-cycle morphology.

RESULTS

Follicle dimensions were (mean +/- SD): upper lid follicle depth, 1.8 +/- 0.3 mm; bulb width, 188 +/- 44 microns; shaft width, 205 +/- 28 microns; lower lid follicle depth, 0.9 +/- 0.2 mm; bulb width 132 +/- 19 microns; and shaft width, 158 +/- 26 microns. The upper lid comprised 41% active follicles compared to 15% in the lower lid.

CONCLUSIONS

There are significant differences in the anatomy of the follicles between the two lids. For an electrolysis needle to completely contact 95% of all follicles, it must be inserted 2.4 mm into the upper lid and 1.4 mm into the lower lid (mean depth +2 SD). Argon laser ablation requires a beam width of < 200 and < 250 microns for the lower and upper lids, respectively, to treated similar depths as electrolysis. The higher proportion of actively growing upper lid follicles explains why upper lid lashes are longer.

The true rate of success in argon laser eyelash thermoablation

Argon laser thermoablation has a success rate of 50% typically, when success is defined as an absence of recurrence of any eyelash per lid treated. When success is redefined as an absence of recurrence per eyelash treated, the success rate increases to 76% to 93%. Laser thermoablation potentially offers selective eyelash ablation with minimal inflammation and adjacent tissue damage. Its true rate of success may be better than previously indicated.

Anterior lamellar repositioning and grey line split for upper lid entropion in ocular cicatricial pemphigoid

PURPOSE

Trichiasis in ocular cicatricial pemphigoid (OCP) is usually due to cicatricial entropion and is a major cause of ocular morbidity. Unfortunately in this disease, direct surgery on the conjunctiva often results in marked inflammation and cicatrisation. This paper assessed a procedure that corrects cicatricial entropion of the upper lid while avoiding surgery to the conjunctiva.

METHODS

A grey line upper lid split and a vertical anterior lamellar repositioning was performed on 16 lids of 11 patients with OCP.

RESULTS

Anatomical success was achieved in 72% of lids at 1 year and 61% had complete success with no lashes touching the globe. These outcomes were maintained up to 4 years. There were no perioperative complications. Two patients post-operatively developed severe conjunctival inflammation that required systemic immunosuppression. The causes of failure were primary surgical failure (n = 2), progression of cicatrisation secondary to surgically induced inflammation (n = 1), development of misdirected lashes (n = 1) and late recurrence at 7 months (n = 1). One patient developed peaking of the eyelid.

CONCLUSIONS

This procedure has a good long-term outcome with minimal complications. Activation of severe conjunctival inflammation occurred in 13% of cases and this must be considered pre- and post-operatively.

Apparent accommodation and depth of field in pseudophakia

PURPOSE

To assess depth of field in phakic and pseudophakic eyes to explain good distance and uncorrected near visual acuity in pseudophakic eyes.

SETTING

Department of Ophthalmology, University of Otago Medical School, Dunedin, New Zealand.

METHODS

Depth of field was measured in pseudophakic (n = 10) and phakic (n = 10) eyes for both near and distant targets. Test conditions included cycloplegia and a constant pupillary aperture using a soft contact lens with a central artificial pupil diameter of 2.5 mm.

RESULTS

There was no statistically significant difference between phakic and pseudophakic eyes for any test. Depth of field for near visual acuity was +/-0.85 diopters (D), but amplitude of legibility was +/-1.94 D. Depth of field for distance visual acuity was between 0.25 and 0.50 D in 85% of eyes.

CONCLUSION

In the absence of astigmatism and disease, a pseudophakic eye with -0.75 D of myopia can expect to achieve 20/30 uncorrected distance acuity and read N5 unaided if the pupil is approximately 2.5 mm.

Sulphapyridine--a new agent for the treatment of ocular cicatricial pemphigoid

AIMS

Ocular cicatricial pemphigoid (OCP) is a severe, potentially sight threatening systemic disease that sometimes requires systemic immunosuppression. This study assessed the clinical outcome of patients with OCP treated with sulphapyridine, a sulphonamide with an anti-inflammatory and immunosuppressive action but few side effects.

METHODS

A prospective, single armed, unmasked clinical trial was undertaken at Moorfields Eye Hospital. Twenty consecutive patients with moderate or marked conjunctival inflammation due to OCP were treated with oral sulphapyridine 500 mg twice daily. The degree of ocular inflammation was assessed as nil, mild, moderate, marked, or severe. Success was defined as resolution to mild or less. Ocular limbitis, systemic features of the disease, and side effects of the drug were also monitored.

RESULTS

Follow up was a mean of 12.3 (SD 4.0) months and ranged from 7 to 17 months. A successful reduction in inflammation was recorded in 22/39 eyes (56%) and 10/20 patients (50%). This improvement occurred within 1 month in 64% and in all by 2 months. Three patients developed allergy. Other side effects included nausea (n = 3), headache (n = 1), urinary hesitancy (n = 1), and mild lymphocytopenia (n = 1). These were dose dependent. Progression of cicatrisation was observed in 1/22 eyes. Success was less likely if there were systemic features of OCP or ocular limbitis.

CONCLUSIONS

Sulphapyridine was clinically effective in 50% of patients with moderate marked inflammation and had few side effects. It is a good alternative to dapsone.

Biofilm formation in infectious crystalline keratopathy due to Candida albicans

Infectious crystalline keratopathy (ICK) is an uncommon, indolent corneal infection in which the slow clinical course contrasts with the rapid laboratory growth and microbiological sensitivities of the infecting organism. This prospective study aimed to determine whether biofilm production was the cause of this disparity. A case of failed medical management of ICK in a patient with Stevens-Johnson syndrome is presented. A penetrating keratoplasty yielded corneal tissue that was freshly fixed for electron microscopy using 0.05% ruthenium red and 2.5% gluteraldehyde. Candida albicans was grown from 3/3 broths, and fungi with morphology consistent with Candida were seen on histological examination. Electron microscopy revealed microorganisms morphologically typical of Candida surrounded by a polysaccharide-rich glycocalyx consistent with a biofilm. We concluded that Candida albicans is capable of producing a biofilm and is a known cause of ICK. This case is supportive evidence that biofilm production is associated with cases of ICK and may explain the chronic, pauciinflammatory features of ICK and its relative resistance to antibiotic treatment.

Progression of disease in ocular cicatricial pemphigoid

BACKGROUND

Ocular cicatricial pemphigoid (OCP) is a sight threatening autoimmune disease that can lead to severe conjunctival cicatrisation and keratopathy. It has a variable course and little is known about the factors that determine disease progression. This study analysed the factors that have prognostic significance regarding disease outcome, progression, and keratopathy.

METHODS

Sixty six patients with OCP were monitored prospectively at Moorfields Eye Hospital. The influence of ocular features, the systemic disease, and the management were analysed to identify factors that influence the outcomes and disease progression.

RESULTS

The mean age at presentation was 67 years; 56% were men. The binocular visual acuities were 6/24 or worse in 25%. Extensive cicatrisation at presentation was common but correlated only weakly with the visual prognosis. Systemic manifestations included lesions of the mouth in 44%, pharynx in 30%, oesophagus in 27%, nose/sinus in 18%, and skin in 17%. There was no association between the ocular and systemic manifestations. Persistent corneal epithelial defects and limbitis occurred in 18% and 32%, respectively, and both were associated with a worse visual prognosis. Systemic immunosuppression was ultimately prescribed in 74%, mainly in patients with advanced stages of conjunctival cicatrisation. Of patients with more than 24 months follow up, progression of cicatrisation occurred in 35% of eyes (16/46) all but one of which were associated with episodes of conjunctival inflammation.

CONCLUSIONS

Persistent epithelial defects, limbal inflammation, and ongoing conjunctival inflammation are important factors that lead to keratopathy and visual handicap. These require aggressive management, often with systemic immunosuppressive treatment. Close follow up is required in cases with extensive cicatrisation.

Inferior retractor plication surgery for lower lid entropion with trichiasis in ocular cicatricial pemphigoid

AIMS

To assess the outcome of inferior retractor plication surgery for lower lid entropion in patients with ocular cicatricial pemphigoid (OCP). This technique avoids surgery on the conjunctiva that can result in exacerbations of disease activity.

METHODS

This prospective study assessed the outcomes of a standard 'Jones' type plication in 14 lids of 10 patients with OCP. Seven patients were taking systemic immunosuppression and no patients had conjunctival inflammation for the 4 months before surgery.

RESULTS

Life table analysis showed a 77% chance of anatomical success at 2 years and a 54% chance of completely preventing lash-globe touch. The surgery did not cause clinical activation of conjunctival inflammation or other complications. Anatomical failure was primary (n = 2) and due to late cicatrisation (n = 1). Three further cases had restoration of normal anatomy but the patients had persistently misdirected lashes that touched the globe.

CONCLUSION

This technique gives good anatomical success over long periods and is particularly safe when there is no conjunctival inflammation present before surgery.

Diagnosis and management of an occult cyclodialysis cleft

Images

Role of cyclophosphamide and high dose steroid in ocular cicatricial pemphigoid

AIMS/BACKGROUND

Ocular cicatricial pemphigoid (OCP) can present with severe conjunctival inflammation that requires systemic immunosuppression to avoid serious ocular morbidity. This study aimed to assess the clinical response to cyclophosphamide and short term, high dose prednisolone in this group of patients.

METHODS

A prospective, unmasked study assessed patients presenting with either 'severe' ocular inflammation (n = 4) or 'marked' or 'severe' ocular inflammation that had failed to respond to other systemic immunosuppression (n = 6). Nineteen inflamed eyes of 10 consecutive patients were enrolled.

RESULTS

The ocular inflammation resolved in 15 eyes in a mean time of 2.4 months. Two eyes perforated despite treatment and one patient was unable to tolerate the medication. Progressive cicatrisation occurred in 21%.

CONCLUSION

Cyclophosphamide and short term, high dose prednisolone are effective in severe inflammation caused by OCP but may not completely prevent cicatrisation.

Biofilm-related infections in ophthalmology

A biofilm is a functional consortium of microorganisms organised within an extensive exopolymer matrix. Organisms within a biofilm are difficult to eradicate by conventional antimicrobial therapy and can cause indolent infections. This paper reviews the pathophysiology of biofilms and their application of ophthalmology. Under certain environmental conditions such as nutrient limitation, some bacteria may secrete and reside in an exopolysaccharide glycocalyx polymer. This confers relative protection from humoral and cellular immunity, antibiotics and surfactants. Biofilms occur in natural aquatic ecosystems, on ship hulls, in pipelines and on the surface of biomaterials. They cause clinical infections of prosthetic hip joints, heart valves and catheters. Biofilm formation may occur rapidly on contact lenses and their cases and hence contribute to the pathogenesis of keratitis. Formation of biofilms is also implicated in delayed post-operative endophthalmitis and crystalline keratopathy. Bacteria within biofilms are 20-1000 times less sensitive to antibiotic than free-living planktonic organisms. Existing experimental methods for modifying biofilm include the use of macrolide antibiotics that specifically impair biofilm production, and the use of enzymes to digest it. These may have clinical applications, as potential adjunctive therapies to antibiotic treatment, for these resistant infections. In conclusion, biofilm is an important cause of infections associated with biomaterials. Novel strategies are needed to deal with these.

Combined trabeculotomy-trabeculectomy compared with primary trabeculectomy for congenital glaucoma

This paper aimed to assess the outcome of primary trabeculectomy for congenital glaucoma and to compare it with a combined trabeculotomy-trabeculectomy procedure. The combined procedure was assessed using a prospective trial for children with primary glaucoma under the age of 1 year (n = 16). The primary trabeculectomy was assessed retrospectively using similar patients treated at the same hospital from 1981 to 1990 (n = 44). After 24 months of follow up, the cumulative chance of success of the primary trabeculectomy was 72% and this was compared with the combined procedure of 93.5%. Primary trabeculectomy achieved good intraocular pressure control for up to 10 years. Follow up for the combined procedure ranged from 19 to 27 months. Complications included hyphaema (4/16 and 4/44) and cataract (0/16 and 3/44). Primary trabeculectomy for congenital glaucoma gives adequate long term success with few complications. The combined procedure may have a higher success rate and this requires further investigation.

Cryotherapy for trichiasis in ocular cicatricial pemphigoid

Trichiasis is a common and potentially sight threatening complication of ocular cicatricial pemphigoid and is usually secondary to cicatricial entropion. This study aimed to assess the success and complications of eyelid cryotherapy for trichiasis in a group of patients with long term follow up. The case records of all patients with ocular cicatricial pemphigoid that attended the external disease clinic at Moorfields Eye Hospital from 1980 to 1992 were reviewed. Each eyelid was divided into three horizontal zones. Cryotherapy was delivered with an Amoilette cryoprobe for approximately 30 seconds. Failure of the cryotherapy was defined as a regrowth of the eyelashes within the treated zone that either required epilation for symptom control or caused keratopathy. Ninety two lid zones were treated, involving 25 lids of 12 patients. The cumulative chance of success decreased rapidly to 40% over the first year. Thereafter, the chance of success declined slowly to 34% at 4 years. Complications included lid notching (n = 2), tarsal atrophy (n = 1), altered lid contour (n = 1), and temporarily raised intraocular pressure (n = 1). All patients had quiescent disease at the time of the cryotherapy and no patients showed increased conjunctival disease activity after treatment. Six patients were taking systemic immunosuppression medication. When ocular cicatricial pemphigoid is quiescent, lid cryotherapy has an acceptable complication rate. The major reason for recurrence of the trichiasis was attributed to inadequate follicle freezing.