Post-acute phase and sequelae management of epidermal necrolysis: an international, multidisciplinary DELPHI-based consensus

BACKGROUND

Long-term sequelae are frequent and often disabling after epidermal necrolysis (Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN)). However, consensus on the modalities of management of these sequelae is lacking.

OBJECTIVES

We conducted an international multicentric DELPHI exercise to establish a multidisciplinary expert consensus to standardize recommendations regarding management of SJS/TEN sequelae.

METHODS

Participants were sent a survey via the online tool "Survey Monkey" consisting of 54 statements organized into 8 topics: general recommendations, professionals involved, skin, oral mucosa and teeth, eyes, genital area, mental health, and allergy workup. Participants evaluated the level of appropriateness of each statement on a scale of 1 (extremely inappropriate) to 9 (extremely appropriate). Results were analyzed according to the RAND/UCLA Appropriateness Method.

RESULTS

Fifty-two healthcare professionals participated. After the first round, a consensus was obtained for 100% of 54 initially proposed statements (disagreement index < 1). Among them, 50 statements were agreed upon as 'appropriate'; four statements were considered 'uncertain', and ultimately finally discarded.

CONCLUSIONS

Our DELPHI-based expert consensus should help guide physicians in conducting a prolonged multidisciplinary follow-up of sequelae in SJS-TEN.

Mucocutaneous inflammation in the Ikaros Family Zinc Finger 1-keratin 5-specific transgenic mice

BACKGROUND

Our genomewide association study documented an association between cold medicine-related Stevens-Johnson syndrome/toxic epidermal necrolysis (CM-SJS/TEN) and Ikaros Family Zinc Finger 1 (IKZF1). Few studies examined biological and pathological functions of IKZF1 in mucosal immunity. We hypothesized that IKZF1 contributes to the mucocutaneous inflammation.

METHODS

Human skin and conjunctival tissues were obtained for immunohistological studies. Primary human conjunctival epithelial cells (PHCjECs) and adult human epidermal keratinocytes (HEKa) also used for gene expression analysis. We also generated K5-Ikzf1-EGFP transgenic mice (Ikzf1 Tg) by introducing the Ik1 isoform into cells expressing keratin 5, which is expressed in epithelial tissues such as the epidermis and conjunctiva, and then examined them histologically and investigated gene expression of the epidermis. Moreover, Ikzf1 Tg were induced allergic contact dermatitis.

RESULTS

We found that human epidermis and conjunctival epithelium expressed IKZF1, and in PHCjECs and HEKa, the expression of IKZF1 mRNA was upregulated by stimulation with polyI:C, a TLR3 ligand. In Ikzf1 Tg, we observed dermatitis and mucosal inflammation including the ocular surface. In contact dermatitis model, inflammatory infiltrates in the skin of Ikzf1 Tg were significantly increased compared with wild type. Microarray analysis showed that Lcn2, Adh7, Epgn, Ifi202b, Cdo1, Gpr37, Duoxa1, Tnfrsf4, and Enpp5 genes were significantly upregulated in the epidermis of Ikzf1 Tg compared with wild type.

CONCLUSION

Our findings support the hypothesis that Ikaros might participate in mucocutaneous inflammation.

Identification of a novel HLA-B allele, HLA-B*5904

The new human leukocyte antigen (HLA) class I allele, HLA-B*5904 was identified in Japanese individual. HLA-B*5904 differs from HLA-B*5901 by two non-synonymous nucleotide exchanges at codon 163 (ACG to CTG).

Association of Fas Ligand gene polymorphism with Stevens-Johnson syndrome

BACKGROUND

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are acute severe blistering diseases of the skin and also two of the most devastating ocular surface diseases leading to corneal damage and loss of vision. The extreme rarity of cutaneous and ocular surface reactions to drug therapies led us to suspect individual susceptibility. SJS/TEN patients in the acute stage were reported to manifest increased serum levels of Fas Ligand (FasL). Thus, we performed SNP association analysis of the FasL gene.

METHODS

In 76 Japanese SJS/TEN patients with ocular surface complications and 160 Japanese healthy controls, we examined four SNPs of FasL reported in the Japanese Single Nucleotide Polymorphisms (JSNP) database by sequencing.

RESULTS

The SNP rs.3830150 A/G showed a significant strong inverse association with SJS/TEN. Analysis of the genotype pattern of SNPs rs.3830150 and rs.2639614 (rs.3830150 A/A-rs.2639614 G/G) also manifested a strong inverse association with SJS/TEN.

CONCLUSION

FasL gene polymorphisms might be associated with SJS/TEN.

Current progress and challenges in ocular surface reconstruction using cultivated epithelial sheet transplantation

The cultivated epithelial transplantation is a new surgical modality for treating a variety of severe ocular surface disorders. This type of tissue-engineered epithelial sheet provides a rapid epithelial coverage on the corneal surface that reduces inflammation and postoperative complications. Although cultivated corneal epithelial transplantation is an effective surgical strategy, autologous transplantation is limited to unilateral cases. Autologous cultivated oral mucosal epithelial transplantation (COMET) enables surgeons to reconstruct the ocular surface using autologous, non-ocular surface cells, and has opened a new pathway for treating severe, bilateral ocular surface disorders.

Transplantation of cultivated autologous oral mucosal epithelial cells in patients with severe ocular surface disorders

BACKGROUND/AIMS

To determine outcomes of transplants of cultivated autologous oral epithelial cells in patients with severe ocular surface disorders.

METHODS

The eyes (n = 6) of four patients with Stevens-Johnson syndrome (three eyes) or chemical burns (three eyes) were studied. Autologous oral epithelial cells, grown for 2-3 weeks on a denuded amniotic membrane carrier in the presence of 3T3 fibroblasts, were air lifted. The resultant sheet was transplanted onto the damaged eye, and acceptance of the sheet by the corneal surface was confirmed 48 hours after surgery. The success of ocular surface reconstruction, graft survival, changes in visual acuity, and postoperative complications were assessed and the quality of the cultivated oral epithelial sheet was evaluated histologically.

RESULTS

At 48 hours after transplant, the entire corneal surface of all six eyes was free of epithelial defects indicating complete survival of the transplanted oral epithelium. Visual acuity was improved in all eyes. During follow up (mean 13.8 (SD 2.9) months), the corneal surface remained stable, although all eyes manifested mild peripheral neovascularisation.

CONCLUSIONS

Autologous oral epithelial cells grown on denuded amniotic membrane can be transplanted to treat severe ocular surface disorders.

Immunosuppressive properties of human amniotic membrane for mixed lymphocyte reaction

The combination of allograft limbal transplantation (ALT) and amniotic membrane transplantation (AMT) has been applied in the treatment of severe ocular surface diseases. The beneficial effect of this combination has been thought to result from possible immunosuppressive ability of amniotic membrane (AM). However, the mechanisms of any such ability remain unknown. In this study, we investigated whether human AM has the ability to suppress allo-reactive T cell responses in vitro. For mixed lymphocyte reaction (MLR), lymphocytes isolated from lymph nodes of C57BL/6 mice (Mls1b, Vbeta6+) were cultured with irradiated splenocytes from DBA/2 mice (Mls1a, Vbeta6-) with or without human AM. For carboxyfluorescein diacetate succinimidyl ester (CFSE) experiments, responder lymph node cells were labelled with a stable intracellular fluorescent dye and cultured with irradiated stimulator cells. The ratio of responder Vbeta6+ T cells was then determined by FACS analysis, and the division profiles of responder Vbeta6+ T cells were analysed by CFSE content. Furthermore, Th1 and Th2 cytokine synthesis by allo-reactive T cells in MLR culture supernatants was determined by enzyme-linked immunosorbent assay (ELISA). Addition of AM to the MLR culture resulted in the significant inhibition of thymidine incorporation compared with control culture lacking AM. The population of responder CD4+Vbeta6+ T cells was significantly reduced in the AM-treated culture in comparison to control. CFSE analysis revealed less division and lower proliferation of responder CD4+Vbeta6+ T cells in cultures with AM than without. In addition, allo-rective T cell synthesis of both Th1 (IL-2 and IFNgamma) and Th2 (IL-6 and IL-10) type cytokine was significantly decreased in the presence of AM. These results indicate that human AM has the ability to suppress allo-reactive T cells in vitro. This inhibitory effect likely contributes to the success of the ALT-AMT combination.

Vitreous levels of insulin-like growth factor-I in patients with proliferative diabetic retinopathy

The levels of IGF-I in the vitreous body and the intraocular fluid of patients with proliferative diabetic retinopathy (PDR) were determined using radioimmunoassay (RIA). Eleven vitreous specimens were obtained from the intraocular fluid of eyes of patients with PDR who underwent surgery during the operation. Eleven intraocular fluids from the same patients during reoperations were compared with controls. The expression of IGF-I mRNA in cultured human Muller glial cells was evaluated using reverse transcription-polymerase chain reaction (RT-PCR). The mean IGF-I level in the vitreous samples during initial PDR surgery and reoperation was significantly higher than that found in the vitreous of the control (p < 0.05). The level of IGF-I increased in 6 of the 11 cases. Cultured human Muller cells expressed IGF-I mRNA. The results indicate increased levels of IGF-I both in the initial vitreous and ocular fluid at post-operative re-proliferation. Muller cell is suggested as an origin of local IGF-I production.

Cultivated corneal epithelial stem cell transplantation in ocular surface disorders

PURPOSE

To investigate the outcome of cultivated corneal epithelial transplantation for severe stem cell deficiencies using denuded amniotic membrane (AM) as a carrier.

DESIGN

Retrospective, noncomparative case series.

PARTICIPANTS

Thirteen eyes of 11 patients were studied. These consisted of five eyes with acute Stevens-Johnson syndrome (SJS), two with chronic SJS, one with an acute chemical injury, two with chronic chemical injuries, two with ocular cicatricial pemphigoid, and one with drug-induced pseudopemphigoid. All of these eyes had total stem cell deficiencies.

MAIN OUTCOME MEASURES

Adaptation of the cultivated corneal epithelium onto the host corneal surface was confirmed 48 hours after surgery. The reconstruction of the ocular surface and visual acuity were measured.

METHODS

Corneal limbal epithelium from donor corneas was cultivated for 4 weeks on a denuded AM carrier, with 3T3 fibroblast coculture and air lifting. The cultivated corneal epithelium showed four to five layers of stratification and was well differentiated. After conjunctival tissue removal from the cornea up to 3 mm outside the limbus and subconjunctival tissue treatment with 0.04% mitomycin C, cultivated allocorneal epithelium, including the AM carrier, was transplanted onto the corneal surface up to the limbus. Lamellar keratoplasty, using preserved donor graft without epithelium, was performed simultaneously for five chronic-phase patients showing corneal stromal scarring. Systemic immunosuppression was used to prevent allograft rejection.

RESULTS

In all 13 eyes, the entire corneal surface, on which cultivated allocorneal epithelium had been placed, was free from epithelial defects 48 hours after surgery, indicating complete survival of the transplanted corneal epithelium. Visual acuity improved in all eyes after surgery, and 10 of the 13 eyes were restored to good vision (postoperative visual acuity improved two or more lines) 6 months after the operation. During the follow-up period (mean +/- standard deviation, 11.2 +/- 1.3 months), the corneal surfaces were clear, although three eyes experienced epithelial rejection.

CONCLUSIONS

Cultivated corneal epithelial transplantation using denuded AM as a carrier can be used for severe stem cell deficiencies.

Characteristics of the human ocular surface epithelium

An appreciation of the biological characteristics of the human ocular surface epithelium affords us a great insight into the physiology of the human ocular surface in health and disease. Here, we review five important aspects of the human ocular surface epithelium. First, we recognize the discovery of corneal epithelial stem cells, and note how the palisades of Vogt have been suggested as a clinical marker of their presence. Second, we introduce the concept of the gene expression profile of the ocular surface epithelium as arrived at using a new strategy for the systematic analysis of active genes. We also provide a summary of several genes abundantly or uniquely expressed in the human corneal epithelium, namely clusterin, keratin 3, keratin 12, aldehyde dehydrogenase 3 (ALDH3), troponin-I fast-twitch isoform, ssig-h3, cathepsin L2 (cathepsin V), uroplakin Ib, and Ca(2+)-activated chloride channel. Genes related to limbal and conjunctival epithelia are also described. Third, we touch upon the genetic abnormalities thought to be involved with epithelial dysfunction in Meesmann's dystrophy, gelatinous drop-like corneal dystrophy, and the ssig-h3-mutated corneal dystrophies. Fourth, we provide an update regarding the current state of knowledge of the role of cytokines, growth factors and apoptosis in relation to ocular surface homeostasis and tissue reconstruction; the main factors being epidermal growth factor (EGF), keratinocyte growth factor (KGF), hepatocyte growth factor (HGF), transforming growth factor-ss (TGF-ss), and some inflammatory cytokines. Fifth, corneal epithelial barrier function and dysfunction as measured by fluorophotometry is remarked upon, with an explanation of the FL-500 fluorophotometer and its ability to detect corneal epithelial dysfunction at a subclinical level. The research described in this review has undoubtedly generated a complete understanding of corneal epithelial pathophysiology-an understanding that, directly or indirectly, has helped advance the development of new therapeutic modalities for ocular surface reconstruction.

The epidermal growth factor receptor (EGFR): role in corneal wound healing and homeostasis

To evaluate the role of the epidermal growth factor receptor (EGFR) in corneal epithelial wound healing, the effect of an EGFR inhibitor on epithelial cell proliferation and cell stratification during wound healing was investigated. From 3 days prior to wounding until wound healing was complete, rats were systemically treated with either an EGFR tyrosine kinase inhibitor (ZD1839) at 40 mg kg(-1) day(-1)or 80 mg kg(-1) day(-1), or with vehicle only (control). A single corneal wound was made in the center of 66 rat corneas, using a 6.0 mm glass tube wrapped in tissue paper soaked in n-heptanol. Subsequently, each wound was photographed and measured by a computer-assisted digitizer every 12 hr. To determine the number of cells in S phase, entire corneas were labelled with (3)H-thymidine and subjected to autoradiography at 0, 12, 24 and 48 hr after wounding. Epithelial thickness was also measured at these time points by microscopy. Epithelial wound healing was significantly and dose-dependently delayed following administration of ZD1839. At 24 hr after wounding, the number of S-phase cells in the limbal corneal epithelium was significantly lower in both the treated groups compared with the control group (P < 0.05). In the cornea before wounding (0 hr) and at 48 hr post-wounding, epithelial thickness was also significantly less in treated rats compared with controls (P < 0.05). These results indicate that EGFR inhibition affects epithelial cell proliferation and stratification during corneal epithelial wound healing and may play a role in maintaining normal corneal epithelial thickness.

Interleukin-6 (IL-6) production by cytokine-stimulated human Müller cells

PURPOSE

To investigate whether or not human Müller cells synthesize interleukin (IL)-6.

METHODS

Using RT-PCR, we first confirmed whether cultured human Müller cells express IL-6 mRNA. Then, to determine Müller cell IL-6 production after stimulation, cultured Müller cells were exposed to various concentrations of IL-1beta (0.2 ng/ml, 2 ng/ml, 20 ng/ml) or lipopolysaccharide (LPS) (0.001 microg/ml, 0.1 microg/ml, 10 microg/ml) in 24 hr assays. In addition, to determine Müller cell time-dependent induction of IL-6 production, cultured Müller cells were exposed to IL-1beta (0.02 ng/ml, 2 ng/ml) or LPS (10 microg/ml) for 6, 12, 24, 36 hr. IL-6 production in supernatants was quantified by ELISA:

RESULTS

IL-6 mRNA was expressed in cultured human Müller cells, which produced IL-6 after stimulation with either IL-1beta or LPS for 24 hours. IL-1beta was a significantly more potent stimulator of IL-6 production than was LPS. Exposure of cultured human Müller cells to either IL-1beta or LPS stimulated IL-6 production in a time-dependent fashion.

CONCLUSIONS

Our findings indicate that human Müller cells can produce IL-6 when stimulated by IL-1beta or LPS. Müller cell IL-6 production may have an important role in various conditions involving ocular inflammation

Expression of sex steroid hormone receptors in human cornea

PURPOSE

Previously we reported the occurrence of estrogen receptor alpha (ER beta), estrogen receptor beta (ER beta) and androgen receptor (AR) in mouse corneas. The present study was designed to investigate the occurrence of various sex steroid hormone receptors, including ER alpha, progesterone receptor (PR) and AR, in human corneas.

METHODS

We used reverse transcription-polymerase chain reaction (RT-PCR) to look for sex hormone receptor mRNAs (ER alpha, PR and AR) in human corneal epithelial cells obtained at autopsy. Next, using an immunocytochemical technique, we localized these receptors in donor human corneas.

RESULTS

mRNAs encoding all receptors tested for were found in corneal epithelial cells obtained from male and female donor eyes. Immunocytochemical examination revealed that the receptors were located in the nuclei of corneal epithelial, stromal, and endothelial cells.

CONCLUSIONS

Since receptors for both male and female sex hormones are present in human corneas of both genders, we postulate that the receptors may influence the biological functions of corneal cells through direct interaction with specific hormones.

Retinal cytokine response in mouse alkali-burned eye

The kinetics of inflammatory cytokines in sensory retina of mice with corneal alkali-burned eyes were examined. Retinal samples were collected from ICR mice with unburned and alkali-burned eyes from day 3 to day 14. Enzyme-linked immunosorbent assay was used to quantitate the expression levels of interleukin-1 alpha (IL-1 alpha), IL-1 beta and IL-6. Concentrations of IL-1 beta and IL-6 were significantly elevated at day 3 after alkali burn, and reduced to normal level by day 7. The concentration of IL-1 alpha was below assay sensitivity at all times. A significant elevation of IL-1 beta and IL-6 in the sensory retina may contribute to the retinal inflammatory response in the alkali-burned eyes. This is the first report suggesting that the retina is involved in the damage process of alkali burn.

Conjunctival inflammation in the chronic phase of Stevens-Johnson syndrome

AIMS

To understand the immunopathogenesis of the corneal conjunctivalisation in Stevens-Johnson syndrome.

METHODS

Conjunctivalised corneas from five patients with Stevens-Johnson syndrome were studied immunohistochemically for several cell surface antigens and two cytokines. Chemical injury specimens were also studied.

RESULTS

In all cases, immunohistochemistry revealed LFA-1, CD4, CD8, and CD68 on subepithelial infiltrating cells. Also, HLA-DR and ICAM-1 were found on the surfaces of epithelial cells, subepithelial infiltrating cells, subepithelial fibroblasts, and endothelial cells in blood vessels. IFN-gamma was found in basal epithelial cells; subepithelial cells and subepithelial extracellular matrix CD19 and IL4 were not detected.

CONCLUSIONS

The infiltrating cell population in the Stevens-Johnson syndrome samples includes macrophages, CD4 positive T cells, and CD8 positive T cells. The cytokine expression pattern suggests CD4 positive T cells are Th1 cells. The infiltrating cell population is similar in Stevens-Johnson syndrome and chemical injury conjunctivalised corneas.

Regulatory effects of 1alpha,25-dihydroxyvitamin D(3) on cytokine production by human corneal epithelial cells

PURPOSE

The topical administration of 1alpha,25-dihydroxy-vitamin D(3) [1alpha,25(OH)(2)D(3) ] inhibits Langerhans cell (LC) migration and corneal neovascularization in mice. Since the cytokines that induce LC migration [e.g. interleukin-1 (IL-1)] and corneal neovascularization [e.g. interleukin-8 (IL-8)] are produced by human corneal epithelial cells, we investigated the inhibitory effects of 1alpha,25(OH)(2)D( 3) on cytokine production by these cells in vitro.

METHODS

In this experiment, human corneal epithelial cells, cultured in DMEM-FBS until confluence, were then switched to serum-free DMEM containing insulin, transferrin, and sodium selenite (DMEM-ITS) for 48 hours. Next, they were cultured with DMEM-ITS containing 1alpha,25(OH)(2)D(3 ) at concentrations of 10(-7) M, 10(-11) M, or 10( -15) M, and vehicle only (0.1% ethanol). After 6 or 12 hours in this culture, the supernatants were collected and concentrations of IL-1alpha, IL-1b, and IL-8 were quantified by ELISA.

RESULTS

Significantly lower levels of IL-1alpha and IL-1b were detected in supernatants from cells cultured with 1alpha, 25(OH)(2)D( 3) (10(-7) M, 10(-11) M, and 10(-15) M), compared to cells cultured with vehicle only. This was true at 6 and 12 hours after the addition of 1alpha,25(OH)(2)D(3) (p < 0.05). IL-8 production inhibition by 1alpha,25(OH)(2)D(3), on the other hand, was detected at 6 hours (p < 0.0005) but not at 12 hours (p> 0.1).

CONCLUSIONS

1alpha,25(OH)(2)D(3) inhibits cytokine (IL-1alpha, IL-1b, and IL-8) production by human corneal epithelial cells in vitro. We suspect that 1alpha,25(OH)(2)D(3) can inhibit LC migration and corneal neovascularization, as is seen in ocular surface inflammation.

Growth factors: importance in wound healing and maintenance of transparency of the cornea

The mechanism of corneal wound healing has not been clarified yet. However, evidence has accumulated that various kinds of growth factor such as epidermal growth factor (EGF), fibroblast growth factor (FGF), transforming growth factor (TGF), keratinocyte growth factor (KGF), hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF) play a key role in corneal wound healing. For example, these growth factors are expressed in the corneal epithelial cells, keratocytes and endothelial cells, and their receptors are expressed in the corneal cells. Furthermore, these growth factors promote the proliferation of corneal cells and induce the migration of corneal cells. In addition to the growth factors, inflammatory cytokines such as interleukin (IL)-1, IL-6 and TNF-alpha are involved in corneal wound healing. These cytokines are expressed in the normal and inflammatory cornea after infections, alkaliburn, etc. where they control the growth of corneal cells and induce the migration of corneal cells. Thus, a number of growth factors and cytokines function in the regulation of corneal cell proliferation and in the maintenance of corneal transparency.

Soluble Fas ligand expression in the ocular fluids of uveitis patients

PURPOSE

The expression of Fas ligand (FasL) in ocular tissues is thought to play a critical role in maintaining immune privilege in the eye. In this study, to clarify the involvement of the Fas-FasL system in inflammatory processes of the eye,we examined soluble FasL (sFasL) in ocular inflammation.

METHODS

Using ELISA systems recently developed, sFasL concentrations in aqueous humor (AH) and/or vitreous fluid (VF) were measured. AH was obtained from 17 eyes of 17 uveitis patients and from 12 eyes of 12 non-uveitis (cataract) patients. VF was obtained from 22 eyes of 22 uveitis patients and 7 eyes of 7 non-uveitis (macular hole) patients. Serum levels of sFasL were also determined.

RESULTS

sFasL in AH and VF was below the detection limit of the ELISA systems in all non-uveitis eyes. On the other hand, sFasL was detected in AH from uveitis patients where it measured 367.0 +/- 154.7 pg/ml (mean +/- SEM). sFasL was also detected in VF from uveitis patients where it measured 1132.2 +/- 281.7 pg/ml. None of the sera from patients with or without uveitis contained a detectable level of sFas L.

CONCLUSIONS

sFasL levels in AH and VF are elevated in the eye during ocular inflammation. Fas-FasL mediated apoptosis may play an important role in the regulation of inflammation during uveitis.

Effect of metalloproteinase inhibitor on corneal cytokine expression after alkali injury

PURPOSE

Interleukin (IL)-1alpha and IL-6 levels in the cornea are greatly elevated during the early stages after an alkali burn in mice. The authors investigated the effect of synthetic inhibitor of matrix metalloproteinase (SIMP) on the expression of inflammatory cytokines in alkali-burned murine corneas and evaluated the clinical appearance of the eyes.

METHODS

After 0.5N NaOH-alkali burns to 400 corneas of ICR mice, 200 received 400 microg/ml of SIMP topically 4 times a day while 200 corneas were similarly treated with vehicle only. At days 4, 7 and 14 after injury, each cornea was assigned a clinical score for corneal opacity, corneal epithelial defect, hyphema and cataract. Extracts of injured corneas in each group were then assayed for cytokine production using ELISA systems for IL-1alpha, IL-1beta, IL-6 and tumor necrosis factor-alpha (TNF-alpha).

RESULTS

The levels of IL-1alpha, IL-1beta and IL-6 were significantly lower in the SIMP-treated group than in the vehicle-treated group 7 days after the burn. However, levels of these cytokines were similar in the SIMP and non-SIMP groups at days 4 and 14. Levels of TNF-alpha did not differ between both groups at any postinjury time. In the SIMP-treated corneas, there was less opacification and hyphema formation and epithelial regeneration was faster.

CONCLUSIONS

Topical application of SIMP in alkali-burned murine corneas reduced the expression of IL-1alpha, IL-1beta, and IL-6 and lessened the severity of the injury.

Detection of herpes simplex virus DNA in atypical epithelial keratitis using polymerase chain reaction

AIM

To study herpes simplex virus (HSV) DNA in tears from patients with atypical epithelial keratitis of unknown aetiology.

METHODS

Tear samples were collected from 17 affected eyes of 17 consecutive patients suffering from epithelial keratitis in whom HSV keratitis was suspected but whose diagnosis was difficult on the basis of clinical manifestations alone. Using reduced sensitivity polymerase chain reaction (PCR), tear samples were tested for HSV DNA. Tears from the unaffected eyes of the 17 patients were also examined, along with 38 tear samples from 19 normal volunteers. Southern blot analysis was performed to confirm that amplified DNA bands were specific for HSV. Clinical correlation with photographs of corneal lesions was also investigated.

RESULTS

HSV DNA was detected in tears from the affected eyes of eight of the 17 patients with suspected HSV keratitis. Tears from the affected eyes of the other patients were PCR negative, as were tears from the unaffected eyes of all 17 patients, and from the 38 normal eyes. There was no correlation between PCR results and clinical manifestation of keratitis.

CONCLUSIONS

Based on the sensitivity of the PCR system, eight of 17 suspected HSV keratitis patients were confirmed as suffering from HSV keratitis. HSV keratitis should therefore be considered as a possible diagnosis in atypical epithelial keratitis.

Kinetics of cytokine production in the cornea and trigeminal ganglion of C57BL/6 mice after corneal HSV-1 infection

To investigate the role of cytokines in the pathogenesis of acute herpetic keratitis (HK), we examined the kinetics of cytokine expression in the corneas and the trigeminal ganglia (TG) of C57BL/6Cr (B6) mice after herpes simplex virus type 1 (HSV-1) infection and observed the influence of the targeted disruption of interferon-gamma (IFN-gamma) gene on the clinical course of HK and/or viral clearance. Following corneal infection with HSV-1 Amakata strain, all corneas developed a typical dendritic keratitis. Quantitative analysis using enzyme-linked immunosorbent assay (ELISA) revealed that the expression of interleukin-1alpha (IL-1alpha), IL-5, IL-6, and IFN-gamma in corneas and TGs significantly elevated immediately after infection, peaked between days 2 and 7 postinfection (p.i.), and then diminished. One exception was IFN-gamma, whose expression significantly persisted in the TGs until day 30 p.i. An additional experiment using IFN-gamma-/- (gko) mice revealed that there was no significant difference in the peak level of viral replication in corneas and TGs between gko and B6 mice, although gko mice showed a significant delay of virus clearance in both corneas and TGs (p < 0.005) and higher mortality rate than B6 mice after HSV-1 infection (p < 0.01). These data suggest that the production of proinflammatory cytokines closely correlates with the pathogenesis of HK, and that IFN-gamma plays an important role in enhancing viral clearance from the cornea and TG.

Peripheral lamellar keratoplasty for corneoscleral cyst: three case reports

PURPOSE

To examine whether peripheral lamellar keratoplasty (LKP) using preserved cornea was effective for the treatment of corneoscleral cysts.

METHODS

Three patients with corneoscleral cysts underwent peripheral lamellar keratoplasty. Two patients had no history of trauma or ocular surgery and were considered to have congenital cysts. The other patient had a history of strabismus surgery that had been performed 7 years previously. The anterior wall of the cysts was removed by trephination, and the epithelial membrane lining the posterior wall was peeled off. Lamellar corneal buttons obtained from preserved corneas then were put in place and secured with 8-10 interrupted sutures. In one case, because the cyst was large and extended to the pupillary axis, peripheral LKP was performed for removal of the scleral and peripheral corneal cyst, and the inner wall of the central corneal cyst was removed with vigorous irrigation and a spatula.

RESULTS

Histologic examination showed that all of the cysts were lined with nonkeratinizing epithelial cells. In all three cases, cysts have not reformed after a 1-5-year follow-up.

CONCLUSIONS

The cysts were lined in epithelial cells, and removal of these epithelial cells was considered to be important for the prevention of recurrence. Peripheral LKP is effective for the treatment of corneoscleral cysts, since this procedure removes displaced epithelial cells and reconstructs the thin part of the cornea and sclera.

Cytokine expression during orthotopic corneal allograft rejection in mice

PURPOSE

The acquisition of cell-mediated immunity against donor antigens has been shown to be associated with rejection of orthotopic corneal allografts, but the mechanisms that cause corneal allograft destruction in grafted tissue remain obscure. To determine which T-cell subsets infiltrate graft tissue and cause graft rejection, cytokine expression was examined in corneal tissue after orthotopic corneal allograft.

METHODS

BALB/c mice received orthotopic corneal allografts from either syngeneic BALB/c or allogeneic C57BL/6 donors. At 1 or 4 weeks after grafting, the mice were euthanatized, and their corneas were removed. Corneal tissue was frozen, homogenized, and placed in phosphate-buffered saline (PBS). Each sample consisted of five corneas in 500 ml PBS. After centrifugation, the supernatant was collected, and the concentration of the following cytokines was measured by enzyme-linked immunosorbent assay: interleukin (IL)-1alpha, IL-2, IL-4, IL-10, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha.

RESULTS

Significantly increased amounts of proinflammatory cytokines (IL-1alpha and TNF-alpha) were detected in supernatants from all grafted corneas (both syngeneic and allogeneic) at 1 week after grafting. At 4 weeks after grafting, supernatants from normal corneas, corneas with syngeneic grafts, and corneas with accepted corneal allografts contained undetectable amounts of IL-2 and IFN-gamma, whereas supernatants from corneas with rejected corneal allografts contained significant amounts of IL-2 and IFN-gamma. There were no significant differences in the amounts of IL-4 or IL-10 among all samples. Histologic examination confirmed the expression of IL-2 and IFN-gamma in rejected corneal allografts.

CONCLUSIONS

Because IL-2 and IFN-gamma are secreted primarily by T-helper type 1 (Th 1) cells, whereas IL-4 and IL-10 are secreted by T-helper type 2 (Th 2) cells, these results indicate that Th 1-type cytokines, rather than Th 2-type cytokines, contribute to the rejection of orthotopic corneal allografts in graft tissue.

Inflammatory cytokines in normal human tears

PURPOSE

To elucidate inflammatory cytokine levels in normal human tears, we investigated the concentrations of interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and interleukin-8 (IL-8) both in basal tears and reflex tears of normal healthy eyes.

METHODS

Tear samples were collected from 270 healthy, normal volunteers with no past history of ocular surface disease; the total number of eyes was 295. All tear samples were collected in graduated disposable microcapillaries from the conjunctival cul-de-sac. Reflex tear stimulation was carried out by inserting an applicator into each volunteer's nose. Cytokine levels in basal tears and reflex tears were determined by ELISA. Tears were not diluted, and pooled samples were used for the cytokine assays.

RESULTS

In basal tears, the concentrations of IL-1alpha, -1beta, -6 and -8 were 10.9 +/- 1.2, 12.9 +/- 2.3, 226.2 +/- 29.6 and 731.4 +/- 116.2 pg/ml, respectively. In reflex tears, IL-1beta was not detectable, and the concentrations of IL-1alpha, -6 and -8 were 9.3 +/- 2.7, 11.6 +/- 1.6 and 276.1 +/- 47.5 pg/ml respectively. IL-1beta, -6 and -8 levels in reflex tears were significantly lower than those in basal tears, except for IL-1alpha.

CONCLUSIONS

In the present study, the normal concentration range of inflammatory cytokines in human basal tears was clarified, as a baseline for further studies to examine the levels of these cytokines in tears during disease states.

Transforming growth factor beta2 in the vitreous in proliferative diabetic retinopathy

OBJECTIVE

To evaluate the hypothesis that transforming growth factor beta2 (TGF-beta2) is involved in the cause of proliferative diabetic retinopathy (PDR).

METHODS

We assayed TGF-beta2 levels in the vitreous of patients with PDR and other vitreoretinal disorders. Forty-nine vitreous specimens were obtained from eyes of patients with PDR undergoing vitrectomy, and 19 vitreous specimens from nondiabetic subjects served as controls. We assessed TGF-beta2 levels using an enzyme-linked immunosorbent assay. Both mature and total TGF-beta2 levels were quantified.

RESULTS

The mean (+/- SD) total levels of TGF-beta2 were 2634 (+/- 1652) pg/mL in the patients with PDR and 1305 (+/- 972) pg/mL in controls. The mean (+/- SD) levels of mature TGF-beta2 were 244 (+/- 316) pg/mL in patients with PDR and 79 (+/- 81) pg/mL in controls. Total and mature TGF-beta2 levels were significantly greater in patients with PDR (total TGF-beta2, P <.001; mature TGF-beta2, P <.01). Mature TGF-beta2 levels were higher in the vitreous of patients who had severe fibrous proliferation.

CONCLUSION

The results indicate increased levels of both total and mature TGF-beta2 in the vitreous of patients with PDR, suggesting that TGF-beta2 plays an important role in the pathogenesis of PDR.

Expression of transforming growth factor-beta s and their receptors by human retinal glial cells

PURPOSE

To help test the hypothesis that transforming growth factor beta (TGF-beta) may serve an autocrine function in the retina, we asked whether human Müller (glial) cells in culture express TGF-beta receptors, contain transcripts for various isoforms of this cytokine, and release TGF-beta s into the medium.

METHODS

Using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique with specific primers for TGF-beta 1, -beta 2 and -beta 3 precursors and for TGF-beta type I and type II receptors, we searched for mRNA transcripts expressed by cultured human Müller cells. Also, an ELISA assay allowed quantification of the levels of various TGF-beta s in medium exposed to these glial cells.

RESULTS

Human Müller cells in culture express transcripts for both type I and type II TGF-beta receptors and also for TGF-beta 1 and TGF-beta 2. In conditioned medium, the concentration of TGF-beta 1 in the mature form was below detectable levels, and the total TGF-beta 1 was relatively low (mean = 252 pg/ml in confluent cultures). In contrast, the mean levels of mature (55 pg/ml) and total (2530 pg/ml) TGF-beta 2 were markedly higher.

CONCLUSIONS

Our observations that cultured Müller cells contain mRNA coding for the TGF-beta 2 precursor, release TGF-beta 2 into the medium and express transcripts for both type I and type II TGF-beta receptors are consistent with the idea that this cytokine serves an autocrine function for these glia in the retina.

Effect of transforming growth factor-beta1 and -beta2 on in vitro rabbit corneal epithelial cell proliferation promoted by epidermal growth factor, keratinocyte growth factor, or hepatocyte growth factor

Corneal epithelial wound healing is intimately controlled by a variety of growth factors, such as epidermal growth factor (EGF), keratinocyte growth factor (KGF), hepatocyte growth factor (HGF), and transforming growth factor-betas (TGF-betas). In this study, we investigate the effects of TGF-beta1 and TGF-beta2 on cultured rabbit corneal epithelial cell proliferation promoted by EGF, KGF, or HGF. Both TGF-beta1 and -beta2 dose-dependently inhibited corneal epithelial cell proliferation promoted by KGF (40 ng ml-1) and HGF (40 ng ml-1), and weakly inhibited cell proliferation promoted by EGF (4 ng ml-1). Furthermore, the inhibitory effect tended to be stronger with TGF-beta2 than TGF-beta1. These findings suggest that TGF-beta1 and -beta2 play important roles as negative modulators against the cell proliferation effect of EGF, KGF and HGF.

Cytokine expression in the alkali-burned cornea

PURPOSE

This study investigated the cytokine expression profile in alkali-burned mouse corneas, in order to elucidate the mechanisms of corneal damage and repair.

METHODS

The cytokines expressed in alkali-burned corneas were identified by polymerase chain reaction (RT-PCR), then quantitated using ELISA. Based on the ELISA results, immunohistochemical analyses were performed to localize cytokine expression.

RESULTS

Among the ten cytokines examined, IL-1 (IL-1 beta), IL-6, IL-10 and TNF-alpha mRNA were expressed in alkali-burned corneas. Quantitation revealed that IL-alpha and IL-6 were strongly induced in the early stages of alkali burn, peak production of IL-1 alpha (53.2 pg/cornea) and IL-6 (23.6 pg/cornea) occurring at days 3 and 7, respectively. The production of IL-10 and TNF-alpha was not significantly elevated during the 42 day period after burn. Immunohistochemical analyses revealed that both IL-1 alpha and IL-6 were mainly localized in regenerating epithelial basal cells.

CONCLUSIONS

IL-1 alpha and IL-6 levels in the cornea are dramatically elevated in the regenerated epithelium during the early stages of alkali burn, and may play an important role in associated corneal damage and repair.

High total TGF-beta 2 levels in normal human tears

Mature and total TGF-beta 2 levels were determined in normal human tears, from 37 volunteers, using a quantitative "sandwich' enzyme immunoassay technique. Since this ELISA method recognizes only mature TGF-beta 2, total TGF-beta 2 levels in tears were measured after acid activation. Aqueous humor samples from 9 patients with cataract were also tested as controls. Mature and total TGF-beta 2 in aqueous humor (AH) averaged 182 pg/ml and 737 pg/ml, respectively. The levels of mature TGF-beta 2 in normal human tears ranged from 36 to 71 pg/ml (mean: 55 pg/ml). And the levels of total TGF-beta 2 ranged from 3446 to 14910 pg/ml (mean: 7854 Pg/ml), a very high level. Percentage of mature TGF-beta 2 ranged 0.4 to 1.3% (mean: 0.9%). It is reported for the first time that there are very high levels of total TGF-beta 2 in normal human tears.

Keratinocyte growth factor accelerates corneal epithelial wound healing in vivo

PURPOSE

To examine whether the topical application of keratinocyte growth factor (KGF) can enhance corneal epithelial healing in vivo. In addition, the distribution of S-phase cells in KGF-treated and control corneas was investigated during regeneration and under normal conditions.

METHODS

A 10-mm diameter epithelial defect was made in the center of rabbit corneas. A 50-microliters aliquot of 10 micrograms/ml human keratinocyte growth factor (hKGF) was then applied topically five times a day. The same volume of phosphate-buffered saline (PBS) vehicle was applied to the contralateral eye as a control. Each corneal epithelial defect was subsequently photographed every 12 hours and was measured by a computer-assisted digitizer. For the S-phase cell analysis, entire corneas were labeled with 3H-thymidine and were subjected to autoradiography at 24 hours after wounding or in the normal cornea at 24 hours after the application of KGF or PBS.

RESULTS

Topical application of 10 micrograms/ml hKGF significantly accelerated corneal epithelial wound healing when compared with controls. In the S-phase cell analysis, KGF did not have any effect on normal corneal epithelial cells. However, in the regenerating cornea, the number of S-phase cells in the KGF-treated limbal epithelium was twofold higher than in the controls.

CONCLUSIONS

Topical application of KGF accelerated corneal epithelial wound healing in vivo and increased cell proliferation in the limbal epithelium of the regenerating cornea.

Enhancing effect of platelet-derived growth factors on migration of corneal endothelial cells

To investigate the role of platelet-derived growth factor (PDGF) in corneal wound healing, we examined the effect of human natural PDGF, recombinant PDGF-BB, and PDGF-AA on the migration of rabbit corneal endothelial cells. In a modified Boyden chamber in fetal bovine serum-free conditions, natural PDGF and PDGF-BB, at a concentration of 1-3 or 10 ng/ml, enhanced the migration of endothelial cells, whereas at a higher concentration (10 or 30 ng/ml), this enhanced migration was suppressed; the optimal concentration range for enhancing migration was 3-10 ng/ml. PDGF-AA did not enhance the migration. Natural PDGF and PDGF-BB activity was found for up to 6 h after the beginning of culture, and was completely blocked by anti-PDGF neutralizing antibodies. A checkerboard assay demonstrated that PDGF-BB had a chemotactic effect on the corneal endothelial cell migration. These results suggest that natural PDGF and PDGF-BB, but not PDGF-AA, are involved in corneal wound healing by stimulating the migration of corneal endothelial cells.

Enhancement of growth of rabbit corneal endothelial cells by PDGF

The effect of platelet-derived growth factor (PDGF) on the growth of rabbit corneal endothelial cells and the expression of PDGF receptor mRNA in these cells were examined in the present study. When rabbit corneal endothelial cells were cultured in the presence of natural PDGF, recombinant PDGF-BB, and PDGF-AA for 1, 3, and 5 days, natural PDGF and recombinant PDGF-BB enhanced the growth of the endothelial cells, but PDGF-AA did not. This growth promotion was suppressed by anti-PDGF antibody. PDGF enhanced also the incorporation of 3H-thymidine into the cells. When PDGF was combined with epidermal growth factor (EGF), the additive effect was recognized. The expression of the PDGF receptor mRNA was found in the endothelial cells by the polymerase chain reaction (PCR) method. It was concluded from these results that PDGF enhanced the growth of the corneal endothelial cells and that the PDGF receptor mRNA was expressed in these cells. These results suggest that PDGF may regulate corneal endothelial cell growth.

Transforming growth factor-beta 1, -beta 2 and -beta 3 mRNA expression in human cornea

The expression of TGF-beta 1, TGF-beta 2 and TGF-beta 3 precursors mRNA transcripts in in vivo human corneal cells were studied. Complementary DNA (cDNA) was generated from poly A+RNA extracted from in vivo human corneal epithelial cells, stromal keratocytes and endothelial cells. With the cDNAs as template, polymerase chain reaction (PCR) was carried out using specific primers of TGF-beta 1, TGF-beta 2 and TGF-beta 3 precursors, synthesized by choosing specific nucleotide sequences in the latency-associated peptide region of each precursor. Southern blot analysis of the PCR products was carried out. In corneal epithelial cells, TGF-beta 2 mRNA transcript was strongly expressed; TGF-beta 1 and -beta 3 mRNA transcripts were also expressed; stromal keratocyte samples expressed TGF-beta 1 and -beta 2 mRNA transcripts but not TGF-beta 3 mRNA transcript. Endothelial cells expressed all three transcripts. The present study, together with the authors' previous immunohistochemical study demonstrates that both protein and mRNA of TGF-beta 2-LAP are present in human corneal epithelium, indicating that TGF-beta 2 may play a crucial role in corneal epithelial cell layers.

Paracrine role of keratinocyte growth factor in rabbit corneal epithelial cell growth

Keratinocyte growth factor (KGF), a member of the fibroblast growth factor (FGF) family, is expressed in stromal fibroblasts and acts specifically on cells of epithelial origin as a paracrine mediator. In this study, we examined KGF and KGF receptor (KGF-R) mRNA expression in rabbit corneal epithelial cells and keratocytes, using a reverse transcription polymerase chain reaction (RT-PCR) method. We also examined the effects of KGF on the proliferation of rabbit corneal cells in vitro. mRNA from cultured rabbit skin fibroblasts, conjunctival fibroblasts, corneal epithelial cells and keratocytes was first reverse-transcribed, and then amplified by PCR using primers specific for KGF and KGF-R. KGF mRNA was expressed in skin fibroblasts, conjunctival fibroblasts and keratocytes, but not in corneal epithelial cells. In contrast, KGF receptor mRNA was expressed in corneal epithelial cells, but not in skin fibroblasts, conjunctival fibroblasts or keratocytes. The results of Southern hybridization experiments of PCR products also showed that KGF mRNA was expressed in skin fibroblasts, conjunctival fibroblasts and keratocytes, whereas KGF receptor mRNA was expressed in corneal epithelial cells. Nucleotide sequencing of the PCR products revealed that their sequences were identical to the expected nucleotide sequences. Using the methylene blue method, we found that KGF enhanced the growth of cultured rabbit corneal epithelial cells, but not keratocytes, at a concentration of 0.01 to 100 ng ml-1. Furthermore, KGF also augmented 3H-thymidine incorporation into the corneal epithelial cells. These results suggest that KGF is a paracrine mediator of the proliferation of corneal epithelial cells as well as of keratinocytes in the skin.