Azithromycin treatment increases survival of high-risk corneal allotransplants

An Overview of Corneal Transplantation in the Past Decade

The cornea is a transparent avascular structure located in the front of the eye that refracts light entering the eyes and also serves as a barrier between the outside world and the internal contents of the eye. Like every other body part, the cornea may suffer insult from trauma, infection, and inflammation. In the case of trauma, a prior infection that left a scar, or conditions such as keratoconus that warrant the removal of all or part of the cornea (keratoplasty), it is important to use healthy donor corneal tissues and cells that can replace the damaged cornea. The types of cornea transplant techniques employed currently include: penetrating keratoplasty, endothelial keratoplasty (EK), and artificial cornea transplant. Postoperative failure acutely or after years can result after a cornea transplant and may require a repeat transplant. This minireview briefly examines the various types of corneal transplant methodologies, indications, contraindications, presurgical protocols, sources of cornea transplant material, wound healing after surgery complications, co-morbidities, and the effect of COVID-19 in corneal transplant surgery.

Survey of Rejection Prophylaxis Following Suture Removal in Penetrating Keratoplasty in Germany

BACKGROUND

Penetrating keratoplasty (PK) gets more and more reserved to cases of increasing complexity. In such cases, ocular comorbidities may limit graft survival following PK. A major cause for graft failure is endothelial graft rejection. Suture removal is a known risk factor for graft rejection. Nevertheless, there is no evidence-based regimen for rejection prophylaxis following suture removal. Therefore, a survey of rejection prophylaxis was conducted at 7 German keratoplasty centres.

OBJECTIVE

The aim of the study was documentation of the variability of medicinal aftercare following suture removal in Germany.

METHODS

Seven German keratoplasty centres with the highest numbers for PK were selected. The centres were sent a survey consisting of half-open questions. The centres performed a mean of 140 PK in 2018. The return rate was 100%. The findings were tabulated.

RESULTS

All centres perform a double-running cross-stitch suture for standard PK, as well as a treatment for rejection prophylaxis with topical steroids after suture removal. There are differences in intensity (1 - 5 times daily) and tapering (2 - 20 weeks) of the topical steroids following suture removal. Two centres additionally use systemic steroids for a few days.

DISCUSSION

Rejection prophylaxis following PK is currently poorly standardised and not evidence-based. All included centres perform medical aftercare following suture removal. It is assumed that different treatment strategies show different cost-benefit ratios. In the face of the diversity, a systematic analysis is required to develop an optimised regimen for all patients.

Effects of pre-transplant azithromycin administration on kidney graft function: study protocol for a double-blind randomized clinical trial

Background

Kidney transplantation is the best strategy for the management of end-stage renal disease; however, the outcomes need to improve further. Macrolides show antimicrobial and anti-inflammatory properties in chronic diseases and intraoperatively, and can accumulate in tissues for extended periods. Therefore, theoretically, when administered to a donor and because of accumulation in the donor kidney, macrolides can cause graft immunomodulation and improve kidney transplantation outcomes.

Methods

This study is a single-center, randomized clinical trial. A total of 60 kidney donors will be randomly allocated to the azithromycin or placebo group and treated with a single dose (1 g) of azithromycin or placebo, respectively, 1 day before surgery. Recruitment commenced in September 2016 and is expected to be completed by March 2018. The primary outcome is kidney graft function. The secondary outcomes include rejection rate, urinary tract infections in graft recipients, pain and systemic inflammatory response syndrome in live donors, and complications in both donors and recipients. Outcomes will be evaluated at baseline and every day in the first week after transplantation, as well as at 1 and 3 months post transplantation. Adverse reactions will be documented. If the efficacy of azithromycin in reducing adverse outcomes is confirmed, it would serve as an easy to use, economic intervention able to lower post-transplantation risks.

Discussion

Short and mid-term analyses of blood and urine samples as well as immunological assays will facilitate a more in-depth analysis of the effects of azithromycin on transplantation outcomes.

Trial registration

Iranian Clinical Trial Registry, IRCT201606141853N11, registered on September 5, 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2744-y) contains supplementary material, which is available to authorized users.

[Immunosuppression after corneal transplantation : Clinical standards and novel approaches]

Corticosteroid eye drops are the mainstay of immunosuppressive therapy after routine lamellar and perforating corneal transplantation. Commonly occurring side effects are cataract formation and increased intraocular pressure. Alternative immunosuppressive agents could allow the dosage of glucocorticoids to be reduced. The antibiotic azithromycin is a candidate drug that showed anti-inflammatory properties in cell cultures and animal models and has positive effects on transplant rejection.

Subclinical Herpes Simplex Virus Type 1 Infections Provide Site-Specific Resistance to an Unrelated Pathogen

HSV-1 infections of the cornea range in severity from minor transient discomfort to the blinding disease herpes stromal keratitis, yet most patients experience a single episode of epithelial keratitis followed by re-establishment of a clear cornea. We asked whether a single transient episode of HSV-1 epithelial keratitis causes long-term changes in the corneal microenvironment that influence immune responses to subsequent corneal infection or trauma. We showed that C57BL/6 mouse corneas infected with HSV-1 KOS, which induces transient herpes epithelial keratitis without herpes stromal keratitis sequelae, possessed a significant leukocytic infiltrate composed primarily of CD4⁺ T cells and macrophages along with elevated chemokines and cytokines that persisted without loss of corneal clarity (subclinical inflammation). Chemokine and cytokine expression was CD4⁺ T cell dependent, in that their production was significantly reduced by systemic CD4⁺ T cell depletion starting before infection, although short-term (3-d) local CD4⁺ T cell depletion postinfection did not influence chemokine levels in cornea. Corneas with subclinical inflammation developed significantly greater trauma-induced inflammation when they were recipients of syngeneic corneal transplants but also exhibited significantly increased resistance to infections by unrelated pathogens, such as pseudorabies virus. The resistance to pseudorabies virus was CD4⁺ T cell dependent, because it was eliminated by local CD4⁺ T cell depletion from the cornea. We conclude that transient HSV-1 corneal infections cause long-term alterations of the corneal microenvironment that provide CD4-dependent innate resistance to subsequent infections by antigenically unrelated pathogens.

Comparison of the Anti-angiogenic and Anti-inflammatory Effects of Two Antibiotics: Clarithromycin Versus Moxifloxacin

PURPOSE

Clarithromycin is a 14-membered ring macrolide antibiotic with anti-inflammatory as well as antibacterial activity, and has been used worldwide. Moxifloxacin is a leading fourth generation quinolone antibiotic that has been used worldwide perioperatively. We intended to evaluate whether clarithromycin can suppress angiogenesis and inflammation in the cornea, and to compare the anti-inflammatory and anti-angiogenic effects of the two antibiotics, clarithromycin and moxifloxacin.

METHODS

We made a murine corneal suture model and tested the anti-inflammatory and anti-angiogenic effects of clarithromycin (5 mg/ml) and moxifloxacin (5 mg/ml) in two randomly divided groups. Dexamethasone (5 mg/ml) was used as a positive control. After making two sutures on the cornea, we performed subconjunctival injections (10 μl) on each group on the day of suture, and every day thereafter until the 8th day post-suture. After harvesting corneas on the 8th post-suture day for immunohistochemical staining, we compared neovascularization (NV), lymphangiogenesis (LY) and inflammatory cell infiltration among the groups.

RESULTS

Clarithromycin suppressed NV, LY and inflammatory infiltration, compared with phosphate-buffered saline (PBS). However, moxifloxacin did not suppress NV, LY, or inflammatory infiltration, compared with PBS. Comparison between clarithromycin and moxifloxacin, clarithromycin showed a tendency of decreasing LY (p = 0.063) and had less inflammatory cell infiltration (p < 0.05) than did the moxifloxacin group. The anti-(lymph)angiogenic and anti-inflammatory effects of clarithromycin were as high as those of dexamethasone.

CONCLUSION

Clarithromycin suppressed LY and inflammation in the cornea, and its anti-inflammatory effect was significantly superior to that of moxifloxacin.

Corneal inflammation after miniature keratoprosthesis implantation

PURPOSE

To compare corneal inflammation after syngeneic and allogeneic penetrating keratoplasty (PK) with miniature Keratoprosthesis (m-KPro) implantation in mice.

METHODS

BALB/C (syngeneic) or C57BL/6 (allogeneic) corneas were transplanted onto BALB/C host beds as part of PK or m-KPro implantation. Corneal inflammation was assessed by determining the frequencies of CD45(+) leukocytes, CD4(+) T cells, CD11b(+) cells, and Gr-1(+) granulocytes/monocytes by flow cytometry at 2, 4, and 8 weeks post transplantation. In addition, expression levels of the proinflammatory cytokines TNF-α and IL-1β were analyzed using real-time qPCR at 8 weeks post transplantation.

RESULTS

Cell frequencies in the syngeneic (syn) and allogeneic (allo) m-KPro groups were higher compared with the syngeneic and allogeneic PK groups, respectively, at all time points. However, after week 4, frequencies of all analyzed immune cells were higher in the alloPK group as compared with synKPro group. At 8 weeks, the expression of TNF-α was higher in synKPro, alloPK, and alloKPro groups compared with the naïve and synPK groups. The expression of IL-1β was significantly higher in both KPro groups as compared with PK groups.

CONCLUSIONS

Although the m-KPro device augments the inflammatory response in the cornea after its implantation, allogenicity (of the carrier tissue) is also a significant contributor to corneal inflammation. These data suggest that using syngeneic or decellularized corneal tissue as a Boston-KPro carrier could reduce the postoperative inflammation response.

Murine corneal transplantation: a model to study the most common form of solid organ transplantation

Corneal transplantation is the most common form of organ transplantation in the United States with between 45,000 and 55,000 procedures performed each year. While several animal models exist for this procedure and mice are the species that is most commonly used. The reasons for using mice are the relative cost of using this species, the existence of many genetically defined strains that allow for the study of immune responses, and the existence of an extensive array of reagents that can be used to further define responses in this species. This model has been used to define factors in the cornea that are responsible for the relative immune privilege status of this tissue that enables corneal allografts to survive acute rejection in the absence of immunosuppressive therapy. It has also been used to define those factors that are most important in rejection of such allografts. Consequently, much of what we know concerning mechanisms of both corneal allograft acceptance and rejection are due to studies using a murine model of corneal transplantation. In addition to describing a model for acute corneal allograft rejection, we also present for the first time a model of late-term corneal allograft rejection.

Short-term azithromycin treatment promotes cornea allograft survival in the rat

Background

Any inflammatory response following corneal transplantation may induce rejection and irreversible graft failure. The purpose of this study is to analyze the anti-inflammatory effect of azithromycin (AZM) following experimental keratoplasty in rats.

Methods

Corneal transplants were performed between Fisher-donor and Lewis-recipient rats. Recipients were postoperatively treated three times daily with AZM, miglyol, ofloxacin or dexamethasone eye drops. As an additional control, AZM was applied following syngeneic keratoplasty. Furthermore, short-term treatments with AZM for seven days perioperatively or with AZM only three days prior to the transplantation were compared to appropriate controls. All transplants were monitored clinically for opacity, edema, and vascularization. Infiltrating CD45⁺, CD4⁺, CD8⁺, CD25⁺, CD161⁺ and CD163⁺ cells were quantified via immunohistochemistry.

Results

AZM significantly promoted corneal graft survival compared with miglyol or ofloxacin treatment. This effect was comparable to topical dexamethasone. No adverse AZM effect was observed. Histology confirmed a significant reduction of infiltrating leukocytes. The short-term application of AZM for three days prior to transplantation or for seven days perioperatively reduced corneal graft rejection significantly compared with the controls.

Conclusions

Along with antibiotic properties, topical AZM has a strong anti-inflammatory effect. Following keratoplasty, this effect is comparable to topical dexamethasone without the risk of steroid-induced adverse effects. Short-term treatment with AZM three days prior to the transplantation was sufficient to promote graft survival in the rat keratoplasty model. We therefore suggest further assessing the anti-inflammatory function of topical AZM following keratoplasty in humans.