Systemic cyclosporin A in high risk penetrating keratoplasties: a case-control study

Why Are Corneal Specialists Resistant to Treating Patients Who Have Severe Ocular Surface Disease With Limbal Stem Cell Deficiency?

PURPOSE

To highlight the paucity of surgeons performing ocular surface stem cell transplantation with systemic immunosuppression (OSSTx with SI) for limbal stem cell deficiency (LSCD) patients, suboptimal treatments for LSCD, and obstacles to adoption.

METHODS

A review of the Eye Bank Association of America annual reports and the authors' case volume for OSSTx with SI was performed. Examination of the published literature on corneal surgeries, especially for LSCD, was completed. These findings were combined with our clinical observations to develop this editorial.

RESULTS

Despite techniques and protocols for OSSTx with SI published more than 30 years ago for the treatment of severe bilateral LSCD, only a small number of corneal specialists have adopted these techniques. There is a paucity of attention to this population of patients, with minimal publications to advance this area of our field. We are too often referred patients with LSCD and severe ocular surface disease that have had suboptimal treatments such as penetrating keratoplasties or primary keratoprostheses. Hesitancy for adopting OSSTx with SI is likely due to a lack of exposure to these procedures during training and fear of systemic immunosuppression. Corneal surgeons are likely unaware of the safety of systemic immunosuppression with appropriate monitoring especially when comanaging these patients with an organ transplant specialist.

CONCLUSION

There is a large unmet need for the treatment of corneal blindness secondary to conjunctival and LSCD. For the vast majority of patients, OSSTx should be the first surgical choice to treat these eyes. We hope major ophthalmology centers will meet this need by building programs, and groups of corneal surgeons should collaborate to create regional centers to make this treatment more accessible to help this population.

Local and Systemic Injections of Human Cord Blood Myeloid-Derived Suppressor Cells to Prevent Graft Rejection in Corneal Transplantation

Myeloid-derived suppressor cells (MDSCs) are therapeutic agents to prevent graft rejection in organ transplants by modulating inflammation. Herein, the immunosuppressive effect of human cord blood MDSCs on corneal allograft models was confirmed. CB-MDSCs were locally (subconjuctival, 5 × 10⁵) or systemically (intravenous, 1 × 10⁶) injected twice on days 0 and 7. A corneal transplantation model was established using C57BL/6 and BALB/c mice, and corneal graft opacity was measured to evaluate graft rejection up to 6 weeks. Results showed that graft survival in the MDSCs groups increased compared to vehicle groups after 42 days. Systemic and local MDSC administration inhibited the maturation (MHC-II^hi CD11c+) of dendritic cells (DCs) and the differentiation of interferon γ+ CD4+ Th1 in draining lymph nodes (LNs). However, vehicle groups increased the infiltration of CD3+ T cells and F4/80+ macrophages and produced prominent neovascular and lymphatic vessels into the graft site with increased mRNA expression of VEGF-A/C and VEGFR-1/R-3. Local MDSCs administration showed prominent anti-angiogenic/anti-lymphangiogenic effects even at lower MDSCs doses. Thus, CB-MDSCs could relatively suppress the infiltration of pathological T cells/macrophages into the corneas and the migration of mature DCs into draining LNs Therefore, ocular and systemic MDSCs administration showed therapeutic potential for preventing corneal allograft rejection.

Topical corticosteroids with topical cyclosporine A versus topical corticosteroids alone for immunological corneal graft rejection

PURPOSE

To assess the efficacy and safety of supplementing topical cyclosporine A (CsA) to topical corticosteroids (CS), in the prophylaxis and treatment of corneal graft rejection following penetrating keratoplasty (PK).

METHODS

Meta-analysis. Search was performed in PubMed, CENTRAL, ClinicalTrials.gov, reference lists of articles and conference proceedings. Primary outcomes: 1-year rejection-free survival rate (prophylaxis); resolution rate of rejection episodes (treatment). Secondary outcomes: 6- and 24-month rejection-free graft survival rate, number of rejection episodes during follow-up, time-to-resolution of rejection episode, 12- and 24-months graft survival rate, adverse events. Subgroup analyses were planned for high-risk grafts; primary vs. secondary prophylaxis of graft rejection episodes; and CsA concentrations of 0.05%, 1%, and 2%.

RESULTS

Five studies of moderate methodological quality were included (one retrospective, four RCT), assessing 459 eyes (CS + CsA 226, CS 233). In the prophylaxis setting, supplemental CsA was associated with a higher rejection-free survival rate at 12-months (RR 1.25, 95% CI: 1.00-1.56, p = 0.05) and 24-months post-PK (RR 1.56, 95% CI: 1.15-2.11, p < 0.01), though no differences were found at the 6-months timepoint (p = 0.93). This effect was mostly verified using CsA 2% in the high-risk subset of patients. In the treatment setting, no differences were found in the resolution rate of rejection episodes (p = 0.23). No differences existed on drug-related adverse events.

CONCLUSION

In the prophylaxis of rejection episodes post-PK, the combined regimen of CS + CsA was associated with a higher 1- and 2-year rejection-free graft survival rate. Subgroup analysis mostly supported the use of CsA 2% for high-risk grafts. Further studies are needed to validate these results.

Efficacy of Immunosuppressants in High Rejection Risk Keratoplasty: A Meta-Analysis of Comparative Studies

PURPOSE

To evaluate the prophylactic effects of immunosuppressants in corneal graft rejection after high-risk penetrating keratoplasty.

METHODS

We searched PubMed, Embase, and the Cochrane Library for comparative studies published between 1989 and 2019 that evaluated the efficacy of immunosuppressants for high-risk corneal graft. The primary outcomes were the 1- and 3-year rejection rates. A fixed-effects or random-effects model was used on the basis of the I2 value, and the results were reported as odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Topical tacrolimus (FK506) was more effective than topical cyclosporine A (CsA) at reducing the 1-year graft rejection rate (OR: 0.17; 95% CI, 0.08-0.37, P<0.01). However, the combination of steroid with either topical FK506 (OR: 0.4; 95% CI, 0.16-1.04, P = 0.09) or CsA (OR: 0.74; 95% CI, 0.32-1.71, P= 0.48) did not show significant superiority in preventing immune rejection compared with steroid monotherapy. Mycophenolate mofetil (MMF) was more effective than CsA at reducing the 1-year graft rejection rate (OR: 2.67; 95% CI, 1.50-4.76, P<0.01). However, MMF was not significantly superior to CsA at reducing the 3-year graft rejection rate (OR: 1.21; 95% CI, 0.45-3.25, P = 0.71). For reducing the 1-year rejection rate, MMF (OR: 0.12; 95% CI, 0.03-0.39, P < 0.01) and CsA (OR: 0.28; 95% CI, 0.10-0.76, P = 0.01) were each more effective than the control groups.

CONCLUSIONS

FK506 eye drops, MMF, and systemic CsA were considered to be promising management to prevent rejection in high-risk penetrating keratoplasty in the present study.

Variable Responses to Corneal Grafts: Insights from Immunology and Systems Biology

Corneal grafts interact with their hosts via complex immunobiological processes that sometimes lead to graft failure. Prediction of graft failure is often a tedious task due to the genetic and nongenetic heterogeneity of patients. As in other areas of medicine, a reliable prediction method would impact therapeutic decision-making in corneal transplantation. Valuable insights into the clinically observed heterogeneity of host responses to corneal grafts have emerged from multidisciplinary approaches, including genomics analyses, mechanical studies, immunobiology, and theoretical modeling. Here, we review the emerging concepts, tools, and new biomarkers that may allow for the prediction of graft survival.

Immune reactions after modern lamellar (DALK, DSAEK, DMEK) versus conventional penetrating corneal transplantation

In the past decade, novel lamellar keratoplasty techniques such as Deep Anterior Lamellar Keratoplasty (DALK) for anterior keratoplasty and Descemet stripping automated endothelial keratoplasty (DSAEK)/Descemet membrane endothelial keratoplasty (DMEK) for posterior keratoplasty have been developed. DALK eliminates the possibility of endothelial allograft rejection, which is the main reason for graft failure after penetrating keratoplasty (PK). Compared to PK, the risk of endothelial graft rejection is significantly reduced after DSAEK/DMEK. Thus, with modern lamellar techniques, the clinical problem of endothelial graft rejection seems to be nearly solved in the low-risk situation. However, even with lamellar grafts there are epithelial, subepithelial and stromal immune reactions in DALK and endothelial immune reactions in DSAEK/DMEK, and not all keratoplasties can be performed in a lamellar fashion. Therefore, endothelial graft rejection in PK is still highly relevant, especially in the "high-risk" setting, where the cornea's (lymph)angiogenic and immune privilege is lost due to severe inflammation and pathological neovascularization. For these eyes, currently available treatment options are still unsatisfactory. In this review, we will describe currently used keratoplasty techniques, namely PK, DALK, DSAEK, and DMEK. We will summarize their indications, provide surgical descriptions, and comment on their complications and outcomes. Furthermore, we will give an overview on corneal transplant immunology. A specific focus will be placed on endothelial graft rejection and we will report on its incidence, clinical presentation, and current/future treatment and prevention options. Finally, we will speculate how the field of keratoplasty and prevention of corneal allograft rejection will develop in the future.

Long-term safety outcome of systemic immunosuppression in pig-to-nonhuman primate corneal xenotransplantation

BACKGROUND

Safety concerns exist for corneal recipients under immunosuppression. We report long-term safety results of porcine corneal xenotransplantation under immunosuppression in nonhuman primates.

METHODS

Systemic monitoring data from 49 Chinese rhesus macaques that received pig corneal transplant between 2009 and 2018 were retrospectively reviewed. The recipients were divided into 4 groups depending on the systemic immunosuppressants used: (a) conventional steroid group; costimulation blockade groups ([b] anti-CD154 antibody, [c] anti-CD40 antibody); and (d) commercially available immunosuppressants (anti-CD20 antibody, tacrolimus, basiliximab) group. We compared results of general condition monitoring; hematologic, biochemical, and electrolyte tests; and Rhesus Cytomegalovirus infection monitoring.

RESULTS

All recipients recovered from early weight loss. White blood cell counts significantly decreased at 6 months in the steroid and anti-CD154 groups. Abnormal liver and kidney function and electrolyte imbalance were not observed in all groups. The mean value of Rhesus Cytomegalovirus DNA copies was consistently lower than 200 copies/mL, and antibody titers did not change over time in all groups. Tacrolimus-associated thrombotic microangiopathy was developed in one case, which resolved after discontinuation of tacrolimus. In 2017, a simian varicella virus outbreak led to clinical signs in 5 that received immunosuppressive therapies, of which 3 died.

CONCLUSION

Costimulatory blockade-based and anti-CD20 antibody/tacrolimus-based immunosuppressive therapies seem to be comparably safe with steroid therapy in nonhuman primates receiving corneal xenotransplantation, as they did not reactivate Rhesus Cytomegalovirus and maintained manageable systemic status. Although reactivation is rare, antiviral prophylaxis for simian varicella virus should be considered in immunocompromised hosts.

Outcomes of Keratoplasty After Ocular Surface Stem Cell Transplantation

PURPOSE

To investigate the long-term outcomes of penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) after ocular surface stem cell transplantation (OSST).

METHODS

An observational retrospective review was performed on all patients who underwent OSST followed by either PK or DALK with a minimum of 6-month follow-up.

RESULTS

One hundred two eyes fulfilled the inclusion criteria. The mean time to keratoplasty after OSST was 19 months, and the mean follow-up was 57 months after keratoplasty. A Kaplan-Meier analysis demonstrated 92% graft survival at year 1, 77% at year 2, 62% at year 3, 55% at year 4, and 54% at year 5. During the study period, a total of 44 grafts failed. The mean time to graft failure was 32 months. Preoperative median best-corrected visual acuity for all eyes was 20/550, which improved to 20/100 (P < 0.001) at 1 year postoperatively, 20/60 (P < 0.001) at 2 years, and 20/100 (P < 0.001) at last follow-up.

CONCLUSIONS

Without addressing the underlying stem cell deficiency, keratoplasty in patients with total limbal stem cell deficiency will ultimately fail in all cases. OSST with either subsequent PK or DALK provides successful visual outcomes with an acceptable complication profile.

Systemic Immunomodulatory Strategies in High-risk Corneal Transplantation

The cornea is the most commonly transplanted tissue in the body. Although corneal grafts generally have high success rates, transplantation onto inflamed and vascularized host beds, or so-called high-risk corneal transplantation, has a high rate of graft rejection. The management of this high-risk corneal transplantation is challenging and involves numerous measures. One of the key measures to prevent graft rejection in these cases is the use of systemic immunosuppressive agents. In this article, we will review the systemic immunosuppressive agents most commonly used for high-risk corneal transplantation, which include corticosteroids, cysclosporine A, tacrolimus, mycophenolate mofetil, and rapamycin. Benefits, risks, and published data on the use of these medications for high-risk corneal transplantation will be detailed. We will also summarize novel immunoregulatory approaches that may be used to prevent graft rejection in high-risk corneal transplantation.

Management of high-risk corneal transplantation

The cornea is the most commonly transplanted tissue in medicine. The main cause of corneal graft failure is allograft rejection. The incidence of graft rejection depends on the presence of high-risk characteristics, most notably corneal neovascularization. Although corneal grafting has high success rates in the absence of these risk factors, high-risk keratoplasty is associated with low success rates because of a high incidence of immune-mediated graft rejection. To improve the survival of high-risk corneal transplantation, various preoperative, intraoperative, and postoperative measures can be considered; however, the key step in the management of these grafts is the long-term use of local and/or systemic immunosuppressive agents. Although a number of immunosuppressive agents have been used for this purpose, the results vary significantly across different studies. This is partly due to the lack of an optimized method for their use, as well as the lack of a precise stratification of the degree of risk in each individual patient. New targeted biologic treatments, as well as tolerance-inducing methods, show promising horizons in the management of high-risk corneal transplantation in near future.

Systemic cyclosporine and corneal transplantation

Corneal transplantation is the most commonly performed tissue transplant boasting over a century of history, science, and tradition. While favorable outcomes have been reported after penetrating keratoplasty, rejection remains a major cause of graft failure. The long-term survival rates of this relatively immunologically privileged tissue are only just comparable to those of vascularized organs. While corticosteroids treatment remains the gold standard for postoperative immunomodulation, other agents have been utilized in an ongoing effort to improve graft survival and patient outcomes. One of the most promising immunomodulatory substances whose immunosuppressive effect has revolutionized solid organ transplantation is cyclosporine (CsA). A calcineurin inhibitor, cyclosporine has been used as an immunosuppressive agent in corneal transplantation since the 1980's. Although some studies have shown beneficial effects of cyclosporine in both low- and high-risk corneal transplant patients the use of cyclosporine in rejection prophylaxis and treatment remain controversial and disputable. We herein present a literature review on the role of systemic cyclosporine in corneal transplantation.

Systemic Immunosuppression in High-Risk Penetrating Keratoplasty: A Systematic Review

Cornea transplantation has a high success rate and typically only requires topical immunomodulation. However, in high-risk cases, systemic immunosuppression can be used. We conducted a systematic review on the efficacy and side effects of systemic immunosuppression for high-risk cornea transplantation. The study population was 18 years old or older with a high-risk transplant (two or more clock hours of cornea vascularization or a previous failed graft or a graft needed because of herpes simplex keratitis). A comprehensive search strategy was performed with the help of an information specialist and content experts from ophthalmology. All study designs were accepted for assessment. Level 1 and level 2 screening was performed by two reviewers followed by data abstraction. Forest plots were created whenever possible to synthesize treatment effects. Quality assessment was done with a Downs and Blacks score. From 1,150 articles, 29 were ultimately used for data abstraction. The odds ratios (ORs) for clear graft survival in cyclosporine and controls were 2.43 (95% CI: 1.00 - 5.88) and 3.64 (95% CI: 1.48 - 8.91) for rejection free episodes. Mycophenolate mofetil (MMF) significantly improved the rejection free graft survival rates at 1 year (OR: 4.05, 95% CI: 1.83 - 8.96). The overall results suggested that both systemic cyclosporine and MMF improved 1-year rejection free graft survival in high-risk keratoplasty. Cyclosporine also significantly improved clear graft survival rates at 1 year; however, there were insufficient data to analyze the same in the MMF group. Higher quality studies are needed to understand this issue better.

[Risk factors, clinical presentations, prevention, and treatment of corneal graft rejection]

Corneal transplantation is the most common and successful type of allotransplantation surgery. Post-transplant immune response in keratoplasty is less pronounced than that in other transplantation procedures, which is accounted for by anatomical features of the cornea and, also, its low antigenic potential and active immunosuppression. However, the immune privilege of the cornea can be violated by neovascularization, inflammation, or trauma. Patients who require keratoplasty to restore their sight and whose immune privilege is disturbed, fall into a high-risk group and are likely to demonstrate tissue incompatibility and non-transparent engraftment. Two approaches exist as to how graft rejection can be prevented. One of them involves induction of donor-specific tolerance, the other - non-specific suppression of the recipient's immune response. To avoid tissue incompatibility, measures can be taken to restore the immune privilege of the cornea as well as to induce antigen-specific tolerance, which is considered a promising, thought yet experimental, area of modern transplantology. In clinical practice, one pays most attention to improvement of non-specific immune suppression methods based on interfering in the metabolism of immunocompetent cells. Thus, timely prescriptions and proper immunosuppressive tactics with account to possible risk factors determine the outcome in high-risk patients undergoing corneal transplantation surgery.

Adverse effects of low-dose systemic cyclosporine therapy in high-risk penetrating keratoplasty

PURPOSE

The purpose of this study was to investigate the adverse effects of low-dose oral cyclosporine (CsA) therapy following high-risk corneal transplantation.

METHODS

The medical records from 88 subjects who had undergone high-risk penetrating keratoplasties and had been administered oral CsA were retrospectively analyzed. High risk was defined as a history of graft rejection, three or more quadrants of vascularization, or the presence or history of intraocular inflammation. An initial CsA dose of 3-5 mg/kg per day was given for 3-7 days, followed by 2.5-3.5 mg/kg per day for approximately 1 month. The concentration of CsA was maintained at the target trough level of 120-150 ng/ml for at least 6 months or until serious complications developed. The relationship between the cumulative dose and duration of CsA administration and the adverse systemic effects, including the frequency of herpes keratitis, was evaluated. The incidence of herpes keratitis in the study subjects was compared with the incidence in 185 patients who had not received CsA therapy following penetrating keratoplasty.

RESULTS

The mean survival time of the grafts was 33.6 months. Adverse effects occurred in 81.8 % of subjects. Hypertension, elevated liver enzyme levels, elevated serum creatinine level, and decreased absolute neutrophil count (ANC) were observed in 14.8, 6.8, 5.7, and 5.7 % of subjects, respectively. Simvastatin-induced rhabdomyolysis also developed in one case. Some patients exhibited minor complications, with gastrointestinal problems and hypertrichosis recorded in 5.7 and 3.4 % of subjects, respectively. Hypertension and hepatotoxicity most frequently occurred after 4 to 8 weeks of medication, while ANC decrease and nephrotoxicity generally developed after 24 weeks of treatment, with incidence related to the cumulative dose. Herpes keratitis occurred more frequently (31.8 %) in the CsA-treated subjects than in subjects that did not receive CsA therapy (p = 0.005). Most of the adverse effects were reversed after discontinuation of CsA therapy.

CONCLUSION

The results of this study suggest that low-dose oral CsA therapy may induce various adverse effects, the most common of which are herpes keratitis and hypertension.

Characteristics of immune rejection after allogeneic cultivated limbal epithelial transplantation

PURPOSE

To investigate the characteristics and prognosis of immune rejection after allogeneic cultivated limbal epithelial transplantation (CLET).

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Forty-two eyes of 41 patients undergoing allogeneic CLET for total limbal stem cell deficiency who completed a follow-up of at least 12 months.

METHODS

Allogeneic cultivated limbal epithelial cells using human amniotic membrane as a carrier were transplanted into the recipient eye. Immune rejection occurred in 10 eyes; the medical records of these patients were reviewed.

MAIN OUTCOME MEASURES

Best-corrected visual acuity, corneal opacification and neovascularization, immunofluorescence staining of CD4 and CD8 T cells, and distribution of Langerhans cells (LCs) in the corneal epithelium.

RESULTS

The corneal epithelium became edematous with epithelial rejection lines and peripheral epithelial defects in 6 eyes. Circumlimbal vessels were hyperemic and extended up to the corneal stroma, thus resulting in aggravation of corneal neovascularization in 8 eyes. Corneal stromal opacification was observed in 9 eyes. CD4(+) or CD8(+) T cells were detected in 5 of 6 eyes from which impression cytology specimens were obtained. In vivo confocal microscopy examination revealed an accumulation of LCs in the central and peripheral corneal epithelium. All patients responded to antirejection therapy. One eye developed a second episode.

CONCLUSIONS

The diagnosis of immune rejection after allogeneic CLET mainly depends on typical clinical manifestations. Delayed recognition can result in worsening corneal opacification and neovascularization. Reasonable use of topical immunosuppressives and a close follow-up within 6 months after allogeneic CLET are critical to improve the prognosis.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Corneal Allograft Rejection: Immunopathogenesis to Therapeutics

Corneal transplantation is among the most successful solid organ transplants. However, despite low rejection rates of grafts in the ‘low-risk’ setting, rejection can be as high as 70% when grafted into ‘high-risk’ recipient beds. Under normal homeostatic conditions, the avascular cornea provides a unique environment that facilitates immune and angiogenic privilege. An imbalance in pro-inflammatory, angiogenic and lymphangiogenic mediators leads to a breakdown in corneal immune privilege with a consequent host response against the donor graft. Recent developments in lamellar and endothelial keratoplasties have reduced the rates of graft rejection even more, while providing improved visual outcomes. The corneal layer against which an immune response is initiated, largely determines reversibility of the acute episode. While epithelial and stromal graft rejection may be treated with topical corticosteroids with higher success, acute endothelial rejection mandates a more aggressive approach to therapy due to the lack of regenerative capacity of this layer. However, current immunosuppressive regimens come with the caveat of ocular and systemic side effects, making prolonged aggressive treatment undesirable. With the advent of biologics, efficacious therapies with a superior side effect profile are on the horizon. In our review we discuss the mediators of ocular immune privilege, the roles of cellular and molecular immune players in graft rejection, with a focus on human leukocyte antigen and antigen presenting cells. Furthermore, we discuss the clinical risk factors for graft rejection and compare rates of rejection in lamellar and endothelial keratoplasties to traditional penetrating keratoplasty. Lastly, we present the current and upcoming measures of therapeutic strategies to manage and treat graft rejection, including an overview of biologics and small molecule therapy.

Adverse effects of systemic immunosuppression in keratolimbal allograft

Purpose. Keratolimbal allograft (KLAL) is a treatment for limbal stem cell deficiency. One disadvantage is systemic immunosuppression to avoid rejection. Our purpose was to examine the adverse effects of systemic immunosuppression in KLAL. Methods. A retrospective case review of 16 patients with KLAL who received systemic immunosuppression consisting of a corticosteroid, an antimetabolite, and/or a calcineurin inhibitor was performed. Patients were monitored for signs, symptoms, or laboratory evidence of toxicity. Results. Eleven of 16 patients (68%) experienced an adverse effect. The average age of those with adverse effects was 43.5 years and without was 31.4 years. Ten of 11 patients (91%) had resolution during mean followup of 16.4 months. No serious adverse effects occurred. The most common included anemia, hyperglycemia, elevated creatinine, and elevated liver function tests. Prednisone and tacrolimus were responsible for the most adverse effects. Patients with comorbidities were more likely to experience an adverse effect (82% versus 20%, P = 0.036). Conclusions. KLAL requires prolonged systemic immunosuppression. Our data demonstrated that systemic immunosuppression did not result in serious adverse effects in our population and is relatively safe with monitoring for toxicity. In addition, we demonstrated that adverse effects are more likely in older patients with comorbidities.

Efficacy of postoperative immunosuppression after keratoplasty in herpetic keratitis

PURPOSE

Recurrence of herpetic keratitis and immune reactions is the major cause of graft failures after penetrating keratoplasty as a consequence of herpes simplex keratitis. No treatment regimen is yet considered a standard of care. This retrospective study analyzes the effectiveness of combined systemic acyclovir and immunosuppressive therapy with cyclosporine A (CSA) or mycophenolate mofetil (MMF) after high-risk keratoplasty in herpetic keratitis.

METHODS

A total of 87 high-risk keratoplasties treated with postoperative combined systemic acyclovir and immunosuppressive therapy with CSA or MMF were analyzed retrospectively according to the therapeutic regimen, the degree of preoperative corneal vascularization, and tissue matching of the graft. Endpoints included immunological graft rejection, recurrence of the herpetic keratitis, graft failure, and visual acuity.

RESULTS

There was an overall trend toward an improvement of visual acuity. Graft failure occurred in 13.1%, in all cases after termination of immunosuppression with MMF or CSA. In 4 of 11 cases, immune reactions caused graft failure. Patients with 3 to 4 quadrants of corneal vascularization showed significantly higher rates of graft rejection than patients with 1 to 2 quadrants vascularized or avascular corneas. Herpetic recurrence occurred in 31.8% and caused 18.2% of graft failure. In 7 of 23 cases, graft rejection was induced by herpetic recurrence.

CONCLUSIONS

Graft survival rate and functional outcome after postoperative antiviral and immunosuppressive treatment in cases of penetrating keratoplasties after herpetic keratitis are comparable with results of normal-risk keratoplasties, despite existing high risks for immune rejections or herpetic recurrences.

Clinical outcomes of penetrating keratoplasty after autologous cultivated limbal epithelial transplantation for ocular surface burns

PURPOSE

To report the clinical outcomes of penetrating keratoplasty (PK) after autologous cultivated limbal epithelial transplantation in eyes with limbal stem cell deficiency (LSCD) after ocular surface burns.

DESIGN

Retrospective case series.

METHODS

This study included 47 patients with unilateral LSCD treated by autologous cultivated limbal epithelial transplantation and PK between 2001 and 2010. PK was performed either along with (single-stage; n = 12) or at least 6 weeks after (2-stage; n = 35) limbal transplantation. The primary outcome measure was corneal allograft survival, and failure was defined clinically as loss of central graft clarity. Secondary outcomes were postoperative Snellen visual acuity and complications.

RESULTS

Most patients were young (mean age, 18 ± 11.4 years) males (76.6%) with LSCD resulting from alkali burns (78.7%) and with visual acuity less than 20/200 (91.5%). The mean follow-up was 4.2 ± 1.9 years. Kaplan-Meier corneal allograft survival rate at 1 year was significantly greater in eyes undergoing 2-stage limbal and corneal transplantation (80 ± 6%; median survival, 4 years) compared with single-stage limbal and corneal transplantation (25 ± 13%; median survival, 6 months; P = .0003). Visual acuity of 20/40 or better was attained by 71.4% of eyes with clear corneal grafts. Allograft failure occurred in 26 (60.5%) eyes as a result of graft rejection (57.7%), graft infiltrate (26.9%), or persistent epithelial defects (15.4%). Recurrence of LSCD was more common after single-stage (58.3%) than 2-stage (14.3%) surgery (P = .008).

CONCLUSIONS

The 2-stage approach of autologous cultivated limbal epithelial transplantation followed by PK successfully restores ocular surface stability and vision in eyes with chronic ocular burns. The single-stage approach is associated with poorer clinical outcomes and should be avoided.

Prospective, randomized study of the efficacy of systemic cyclosporine in high-risk corneal transplantation

PURPOSE

Immunologic rejection remains a major cause of graft failure in high-risk corneal transplantation. This study was conducted to elucidate the efficacy and safety of systemic cyclosporine (CsA) in high-risk corneal transplantation.

DESIGN

Prospective, randomized, open-labeled clinical trial with a parallel-group study.

METHODS

Patients underwent high-risk corneal transplantation at the Department of Ophthalmology, Tokyo Dental College, Chiba, Japan. High-risk was defined as corneal neovascularization in more than 1 quadrant or a history of corneal grafting. Patients were assigned to either a systemic CsA group or a control group. Administration of CsA was continued for at least 6 months with blood CsA concentration 2 hours after administration of approximately 800 ng/mL, unless undesirable side effects developed. The main outcome measures were graft clarity, endothelial rejection, and local and systemic complications.

RESULTS

Forty patients were enrolled and 39 (18 men, 21 women; mean age, 67.4 ± 11.9 years) were analyzed. In the CsA group, CsA was discontinued within 6 months in 7 patients because of side effects. With a mean follow-up of 42.7 months, endothelial rejection developed in 6 and 2 eyes in the CsA and control groups, respectively. No differences were observed in the rates of graft clarity loss between the 2 groups (P = .16, Kaplan-Meier analysis).

CONCLUSIONS

No positive effect of systemic CsA administration for suppressing rejection in high-risk corneal transplantation was observed. With a relatively high incidence of systemic side effects, the results suggest that this protocol should not be recommended for corneal transplant recipients, especially those of advanced age.

Sirolimus and mycophenolate as combination prophylaxis in corneal transplant recipients at high rejection risk

PURPOSE

To examine efficacy and safety of dual sirolimus and mycophenolate mofetil systemic immunosuppression as allograft rejection prophylaxis after penetrating keratoplasty in patients at high rejection risk.

DESIGN

Prospective, interventional case series.

METHODS

settings: Single-center subspecialty clinic. patients: Six penetrating transplant recipients at high rejection risk and with no confounding additional cause for high risk of graft failure. All transplant recipient eyes had good visual potential. intervention: Treatment with oral mycophenolate mofetil in combination with sirolimus for 1 year, and sirolimus alone for 2 further years after keratoplasty at doses used in prophylaxis after cadaveric kidney transplantation. main outcomes measures: Interval to first rejection episode, transplant survival, and significant drug adverse effects. Minimum follow-up interval was 13 months after transplantation.

RESULTS

Rejection episodes occurred in 3 patients, one of which led to transplant failure. Of the 6 transplants, 5 remained clear at latest follow-up. Hepatotoxicity required discontinuation of mycophenolate in 1 patient, and both drugs were otherwise free of significant adverse effects.

CONCLUSIONS

Sirolimus and mycophenolate mofetil in combination are effective in extending corneal transplant survival in most but not all high rejection risk patients and generally are well tolerated. Results justify further evaluation of this regimen in a larger controlled study.

Uses and safety profile of ciclosporin in ophthalmology

Ciclosporin is a calcineurin inhibitor that acts by primarily inhibiting the action of T cells. Clinical trials in the early 1980s demonstrated that systemic ciclosporin was a promising steroid-sparing agent and was also effective in patients who are refractory to treatment with corticosteroids. However, recent years have witnessed the emergence of safer immunosuppressive agents due to the poor side-effect profile of systemic ciclosporin. Topical ciclosporin, however, has a much improved safety profile and is still used to treat a variety of ocular surface disorders including dry eye syndrome, vernal and atopic keratoconjunctivitis, severe blepharitis and high-risk corneal graft patients. This article reviews the uses and safety profile of systemic and topical ciclosporin in ophthalmology, as well as discussing alternative therapeutic agents available.

Cyclosporin-A associated malignancy

The use of cyclosporin is well established within the ophthalmology community, especially against sight threatening intraocular inflammation. It is well known however, that immunosuppression in general is a risk factor for the development of malignancy and numerous studies point to the risk imposed by cyclosporin. This article analyses and reviews all relevant studies with regard to the development of malignancy associated with the use of cyclosporin and extrapolates this into the ophthalmic setting. This is to enable clinicians to assess the risks in individual patients and to present a monitoring regime which can be used in patients undergoing cyclosporin treatment. The review is solely concerned with the risk of the development of malignancy following cyclosporin immunosuppression and not with any other adverse effect.

The immunobiology of corneal transplantation

Corneal allotransplantation is highly successful in the short term, but much less successful in the longer term. Many corneal grafts in recipients with corneal neovascularization or the sequelae of ocular inflammation undergo irreversible rejection, despite topical immunosuppression with glucocorticosteroids. Sensitization to cornea-derived alloantigen proceeds by both direct and indirect routes, but the anatomic location of sensitization remains unclear. Multiple and redundant mechanisms operate in the effector phase of corneal graft rejection, which is largely cell-mediated rather than antibody-mediated. Human leukocyte antigen matching may improve outcomes in high-risk patients but systemic immunosuppression is frequently ineffective and is seldom used.

Corneal Graft Rejection

Penetrating keratoplasty is the most widely practiced type of transplantation in humans. Irreversible immune rejection of the transplanted cornea is the major cause of human allograft failure in the intermediate and late postoperative period. This immunological process causes reversible or irreversible damage to the grafted cornea in several cases despite the use of intensive immunosuppressive therapy. Corneal graft rejection comprises a sequence of complex immune responses that involves the recognition of the foreign histocompatibility antigens of the corneal graft by the host's immune system, leading to the initiation of the immune response cascade. An efferent immune response is mounted by the host immune system against these foreign antigens culminating in rejection and graft decompensation in irreversible cases. A variety of donor- and host-related risk factors contribute to the corneal rejection episode. Epithelial rejection, chronic stromal rejection, hyperacute rejection, and endothelial rejection constitute the several different types of corneal graft rejection that might occur in isolation or in conjunction. Corneal graft failure subsequent to graft rejection remains an important cause of blindness and hence the need for developing new strategies for suppressing graft rejection is colossal. New systemic pharmacological interventions recommended in corneal transplantation need further evaluation and detailed guidelines. Two factors, prevention and management, are of significant importance among all aspects of immunological graft rejection. Preventive aspects begin with the recipient selection, spread through donor antigenic activity, and end with meticulous surgery. Prevention of corneal graft rejection lies with reduction of the donor antigenic tissue load, minimizing host and donor incompatibility by tissue matching and suppressing the host immune response. Management of corneal graft rejection consists of early detection and aggressive therapy with corticosteroids. Corticosteroid therapy, both topical and systemic, is the mainstay of management. Addition of immunosuppressive to the treatment regimen helps in quick and long term recovery. Knowledge of the immunopathogenesis of graft rejection may allow a better understanding of the immunological process thus helping in its prevention, early detection and management.

Penetrating keratoplasty in a California Brown Pelican

Fresh homologous penetrating keratoplasty (PK) was performed on the left cornea of a young adult female California Brown Pelican (Pelecanus occidentalis) for the treatment of vision-threatening corneal scarring and granulation tissue. The procedure appeared to be highly successful based on short-term clinical follow-up and histopathology results. However, the patient died from unrelated causes before long-term follow-up could be obtained.

Prevention and Treatment of Corneal Graft Rejection

PURPOSE

This study was designed to analyze current practice patterns in the prevention and treatment of corneal graft rejection and to compare these patterns with previously reported practices.

METHODS

In January 2004, a survey addressing the routine postoperative management of corneal transplants and the treatment of various manifestations of corneal graft rejection was sent to members of The Cornea Society.

RESULTS

Of the 396 surveys, 111 (28%) were returned and analyzed. All respondents used topical corticosteroids for routine postoperative management and treatment of endothelial graft rejection. Prednisolone, in brand or generic form, was used by 37 to 90% for routine management in various clinical scenarios and 81 to 91% for various manifestations of graft rejection at all time points; however, after 6 months, 12 to 26% used loteprednol etabonate for routine management. For routine management of high-risk grafts, 48% used topical cyclosporine in addition to prednisolone. Compared with previous surveys, the use of oral steroids significantly decreased for the routine management of high-risk corneal transplants, and the use of subconjunctival steroids decreased for the management of graft rejection.

CONCLUSIONS

Topical prednisolone remains the mainstay for the prevention and treatment of corneal graft rejection; however, the role of newer agents, loteprednol etabonate and topical cyclosporine, is expanding.

The impact of corneal allograft rejection on the long-term outcome of corneal transplantation

PURPOSE

To examine the influence of corneal allograft rejection on the survival of penetrating corneal transplantation, to review the status of conventional therapies to improve graft survival, and to consider prospects for alternative approaches to reduce the impact of rejection.

DESIGN

Perspective, including prospective, observational cohort study.

METHODS

An examination of the literature on human corneal graft rejection and data from the Australian Corneal Graft Registry, reviewed in the context of clinical experience.

RESULTS

Corneal graft outcome is not improving with era. The sequelae of inflammation, whether occurring before corneal transplantation or subsequently, exert a profound influence by predisposing the graft to rejection. Of the developments that have been instrumental in reducing rejection in vascularized organ transplantation, living-related donation is not an option for corneal transplantation. However, HLA matching may be beneficial and requires reassessment. The evidence base to support the use of systemic immunosuppressive agents in corneal transplantation is thin, and topical glucocorticosteroids remain the drugs of choice to prevent or reverse rejection episodes. Experimental approaches to local allospecific immunosuppression, including the use of antibody-based reagents and gene therapy, are being developed but may be difficult to translate from the laboratory bench to the clinic.

CONCLUSIONS

Corneal allograft rejection remains a major cause of graft failure. High-level evidence to vindicate the use of a particular approach or treatment to prevent or treat corneal graft rejection is lacking. In the absence of extensive data from randomized, controlled clinical trials, corneal graft registers and extrapolation from experimental models provide some clinically useful information.

A novel water-soluble cyclosporine A prodrug: ocular tolerance and in vivo kinetics

The purpose of this study is to demonstrate that a novel water-soluble prodrug of cyclosporine A (CsA) intended for topical ocular administration, does not induce eye irritation in a rabbit model and is able to generate therapeutic concentrations of CsA in the precorneal area immediately after administration. The eye irritancy of the prodrug and CsA control solution was assessed by the Draize test and by confocal laser ophthalmoscopy (CLSO). Residence time and tear concentrations of prodrug and CsA in the rabbit eye were assessed by HPLC. The Draize test showed an excellent tolerance for the prodrug solution while the reference CsA oil solution induced lachrymation and irritation. The CLSO-measured corneal lesions, subsequent to treatment with the prodrug and reference solutions, were 3% and 9%, respectively. The prodrug transformed rapidly, leading to relatively stable CsA concentrations in tears with a maximal concentration of 94 microg ml(-1) over the observation period. This study demonstrated that the prodrug solution was well tolerated and that clinically significant CsA tear concentrations were achieved. UNIL088 is a promising molecule in the treatment of immune-related disorders of the eye.

Prevention of corneal allograft rejection in a mouse model of high risk recipients

AIM

To determine the effectiveness of treatment with immunosuppressive drugs and monoclonal antibodies (mAb) after penetrating keratoplasty in two different models of high risk mouse recipients.

METHODS

Corneas were grafted orthotopically in mouse models of high risk recipients with either neovascularisation of the graft bed or presensitisation to graft donor antigens. Recipients were treated with mAb against CD4(+) or CD8(+) cells or against T cells, or were treated with cyclosporin A (CsA) or mycophenolate mofetil (MMF), or a combination of both drugs.

RESULTS

Control untreated recipients with neovascularised graft bed or presensitised to the graft donor antigens rejected corneal allografts in 12.5 (SD 2.3) and 9.9 (1.6) days, respectively. Treatment of graft recipients with a neovascularised graft bed with mAb anti-CD4 or anti-T cells, but not with mAb anti-CD8 or with immunosuppressive drugs, resulted in a significant prolongation of graft survival; 75% and 28.5%, respectively, of grafts survived for more than 45 days after grafting. However, none of the treatments were successful in presensitised recipients.

CONCLUSIONS

Treatment of high risk recipients with mAb anti-CD4 is more effective in preventing corneal allograft rejection than the treatment with mAb anti-CD8 or the immunosuppressive drugs MMF and CsA. However, the effectiveness of the treatment depends on the recipients' pretransplantation risk type.

Corneal transplantation: the forgotten graft

The most commonly performed transplant is that of the cornea, with 2292 corneal grafts performed in the UK in 2002-03, compared with 1775 renal transplants [1]. In the USA approximately 40 000 transplants are performed every year [2]. However this preponderance is not reflected in the amount of attention given to this transplanted tissue by the scientific community: for example up till now there have been no papers published in the American Journal of Transplantation that have cornea as a key or title word (as determined by a Medline search in December 2003). There are several reasons for this. The first is that corneal grafting is the province of ophthalmologists, who (with notable exceptions) are isolated from the transplant community. The second is that there is a widespread belief that, because of the existence of immune privilege, corneal grafts are not rejected and so there is no need for further research. As we will discuss later, this is incorrect. In this article we will seek to show that study of corneal transplantation is important in its own right, and also that it has lessons for those interested in other forms of allograft.