Acute Endothelial Rejection Research Articles

Near infra-red labelling and tracking of corneal endothelial cells in-vivo

Following corneal transplantation, there is an initial, rapid decline in corneal endothelial cells (CECs) following surgery. Direct imaging of post-transplantation endothelial cells is only possible weeks after surgery and with a limited field of view. We have developed a labelling approach using 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotricarbocyanine iodide (DIR) dye solution, that enables tracking of labelled CECs in vivo for at least 1 month. Initial in vitro optimization, with assessments of dye concentration on fluorescence, cellular toxicity and cell migration, performed in propagated primary CECs. Subsequently, in vivo evaluation of cellular labelling was assessed within a rabbit wound healing model. Finally, real-time visualization of human cadaver donor tissue incubated in DIR transplanted into rabbits was achieved using a clinical confocal microscope. Results revealed detectable fluorescence increased with concentration to a plateau of 100 µg/ml, with no toxicity of CECs at any concentration evaluated. DIR-labelled CECs were detectable in vivo up to 1 month, and transplanted labelled donor graft could be visualized and were trackable in vivo. Acute endothelial rejection in 1 rabbit was evidenced by detectable DIR positive cells within the anterior chamber. DIR imaging allowed for detailed imaging of the transplanted human corneal endothelium, and enabled non-invasive observation of the corneal endothelial morphology following transplantation.

In vivo Confocal Microscopic Evaluation of Corneal Changes in Acute Endothelial Rejection.

Purpose:To evaluate the microstructural corneal changes during acute endothelial graft rejection and following treatment using in vivo confocal microscopy (IVCM).Methods:Patients with a clinical diagnosis of severe acute endothelial graft rejection following penetrating keratoplasty were included in this study. IVCM was performed on the 1st day the patient presented with rejection signs and at the time of clinical resolution.Results:Twenty-three patients were included in this study. Inflammatory cells appeared as dendritic cells (DCs) and less frequently, as non-DCs in basal epithelial and subbasal areas. Activated keratocytes (AKs) (type 1: large cells with visible cytoplasmic processes; type 2: elongated and spindle-shaped keratocytes) were visible in acute phase. Following resolution, type 1 AKs considerably reduced, but type 2 cells were more often persisted. Multiple types of keratic precipitates (KPs) were also visible in acute phase which resolved following resolution of rejection.Conclusions:Acute graft rejection was associated with an increase in the number of DCs, activation of keratocytes, and aggregation of various types of KPs. Inflammatory process subsided in almost all cases, but the IVCM changes did not return to normal early after clinical resolution of rejection.

Characteristics of endothelial corneal transplant rejection following immunisation with SARS-CoV-2 messenger RNA vaccine

AimWe report two cases of endothelial corneal allograft rejection following immunisation with SARS-CoV-2 messenger RNA (mRNA) vaccine BNT162b2 and describe the implications for management of transplant recipients postvaccination for COVID-19.MethodsA...

Outcomes of difluprednate treatment for corneal graft rejection

ObjectiveTo evaluate outcomes of difluprednate treatment in penetrating keratoplasty (PK) graft rejection DesignRetrospective, interventional case series. ParticipantsPatients treated with difluprednate for acute endothelial rejection after PK. MethodsData were collected on resolution of rejection, treatment regimen used, best spectacle-corrected visual acuity (BSCVA), intraocular pressure (IOP), and side effects. Main outcome measure: rate of rejection resolution. Secondary outcome measures: BSCVA change and side-effect rates. ResultsThirty-three eyes of 33 patients aged 56.7 ± 17.9 years were included. Twenty-four grafts (72.7%) were high-risk grafts. Complete treatment success was achieved in 19 of 33 grafts (57.6%) over 1.8 ± 1.4 months. Non-high-risk grafts had 100% treatment success rate (9 of 9 grafts). All treatment failures occurred in high-risk grafts, which had a significantly lower treatment success rate of 41.7% (10 of 24 grafts) compared with non-high-risk grafts (p = 0.004). Mean BSCVA in the treatment-success group improved from 1.07 ± 0.74 logMAR at the time of rejection to 0.44 ± 0.33 logMAR after treatment (p = 0.003). High-dose difluprednate (every 1–3 hours while awake) was used in 93.9% of eyes. IOP elevation and toxic epitheliopathy were each seen in 21.2% of patients. IOP elevation was managed successfully with topical medication and/or difluprednate discontinuation. Epitheliopathy resolved in all cases after completion of difluprednate treatment, except for one case complicated by an infected ulcer. ConclusionsHigh-dose difluprednate was effective in treating PK graft rejection, especially in non-high-risk grafts. Adjunct treatment may be required in high-risk grafts. Monitoring for IOP elevation and for toxic epitheliopathy is recommended.

Topical Tacrolimus as Adjuvant Therapy to Corticosteroids in Acute Endothelial Graft Rejection After Penetrating Keratoplasty: A Randomized Controlled Trial.

To evaluate the efficacy of topical tacrolimus 0.05% as adjuvant therapy to corticosteroids in the treatment of acute endothelial rejection of a penetrating keratoplasty (PKP) graft. Patients with the clinical diagnosis of acute endothelial rejection of a PKP graft were randomized into 2 groups-group 1: receiving topical tacrolimus 0.05% as adjuvant therapy to corticosteroid treatment and group 2: receiving only corticosteroid treatment. Main outcome measures were rejection reversal, time to rejection reversal, and recurrence of rejection. Thirty-one eyes of 31 patients (17 and 14 eyes in group 1 and 2, respectively) were included in the study. The rejection episode completely resolved in 88.2% of patients in group 1 and 85.7% of patients in group 2 [hazard ratio = 0.60, 95% confidence interval (CI) = 0.28-1.29, P = 0.191]. After adjusting for preoperative factors using the inverse-probability weighting method, the time to resolution of rejection was significantly shorter in group 1 than group 2 (average treatment effect = 16, 95% CI, 3.7-28.7, P = 0.013). The recurrence rate of rejection was significantly higher in group 2 (39.7, 95% CI, 12.8-92.6 per 1000 months of follow-up) than in group 1 (3.6, 95% CI, 0.05-19.9 likewise); risk ratio: 11.1, 95% CI, 1.3-95.0, P = 0.028. Topical tacrolimus 0.05% as an adjunct to steroids can hasten the resolution of endothelial rejection of a PKP graft and potentially decreases the recurrence of rejection. However, it may not improve rejection reversal success.

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.

Bedeutung der Cyclosporin-A-Absorption für eine effektive immunmodulatorische Therapie nach Hochrisikokeratoplastik

Cyclosporin A (CsA) is applied as an immune modulator in transplantation medicine, including high-risk keratoplasty. We examined the C(0) and C(2)-CsA serum levels after high-risk keratoplasty. The rate of so-called low absorbers was determined, and the importance of low absorption for the survival and rejection freedom of corneal grafts was examined. Follow-up of 89 high-risk cornea grafts in the patient group (n=32) ranged from 1 to 72 months postoperatively. The evaluation included data about serum levels of CsA C(0) (24 h after oral CsA application) and C(2) (2 h after oral CsA application) and clinical follow-ups. Using statistical methods, CsA C(0) and C(2) levels and clinical data were examined. Low absorbers did not reach the target C(2) levels by CsA dose adjustment. High intraindividual and interindividual variance of CsA C(0) and C(2) values was observed in the examined group of patients. A rate of up to 34.4% (n=11) represented the low absorbers. There was no significance of the low-absorption factor for clear graft survival, rejection freedom, or the rate of side effects observed. An acute endothelial rejection was observed in 23% of grafts and caused 37% of graft failures. In the patients without rheumatic corneal ulcers (n=27), 89% of the corneal grafts remained clear after 12 months, and 52% remained clear after 36 months. In our study, with a low number of patients and multiple cofactors, the influence of low-absorption CsA on the clear corneal graft survival and rejection rates could not be proved statistically. Due to the specific immune status of the cornea, the influence of low absorption may be lower than in organs such as the kidney and liver. In our study, the C(2) serum level of CsA after high-risk keratoplasty did not provide any helpful information about the prognosis of the corneal grafts or CsA treatment monitoring.

The use of a single pulse of intravenous methylprednisolone in the treatment of corneal graft rejection. A preliminary report

In corneal graft rejection, rapid reversal of the rejection process is necessary to minimise endothelial cell loss. Ten consecutive patients with acute endothelial rejection were treated with a single 500 mg pulse of methylprednisolone intravenously and topical prednisolone 1% drops hourly. The rejection episode was successfully reversed in eight (80%) of the 10 grafts. This preliminary trial indicates that cortico-steroid pulse therapy may be beneficial in the management of severe corneal graft rejection with the advantage of avoiding prolonged oral corticosteroid therapy.

THE SPECULAR MICROSCOPIC APPEARANCE OF CORNEAL GRAFT ENDOTHELIUM DURING AN ACUTE REJECTION EPISODE

The specular microscopic appearance of a graft endothelium during a successfully treated acute endothelial rejection episode is reported. Coinciding with the increased thickness of the graft great disturbance in cellular morphology was observed. Individual cells were seen to appear swollen or to show bright intracellular areas. Also abnormalities with respect to cellular intersections were seen with the occurrence of junctional complexes at which more than three cells met. The significance of these abnormalities is discussed. The morphological changes subsided gradually as the graft cleared and the thickness decreased. This study examplifies the value of the non-contact specular microscopic technique which enables a thorough study of the diseased corneal endothelium without traumatizing the cornea and interfering with subsequent specular microscopic examinations.