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Petra Liskova,
Rhian Gwilliam, Martin Filipec,
Katerina Jirsova,
Stanislava Reinstein Merjava,
Panos Deloukas,
Tom R Webb,
Shomi S Bhattacharya,
Neil D Ebenezer,
Alex G Morris,
Alison J Hardcastle
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ABSTRACT: Posterior polymorphous corneal dystrophy (PPCD) is a rare autosomal dominant genetically heterogeneous disorder. Nineteen Czech PPCD pedigrees with 113 affected family members were identified, and 17 of these kindreds were genotyped for markers on chromosome 20p12.1- 20q12. Comparison of haplotypes in 81 affected members, 20 unaffected first degree relatives and 13 spouses, as well as 55 unrelated controls, supported the hypothesis of a shared ancestor in 12 families originating from one geographic location. In 38 affected individuals from nine of these pedigrees, a common haplotype was observed between D20S48 and D20S107 spanning approximately 23 Mb, demonstrating segregation of disease with the PPCD1 locus. This haplotype was not detected in 110 ethnically matched control chromosomes. Within the common founder haplotype, a core mini-haplotype was detected for D20S605, D20S182 and M189K2 in all 67 affected members from families 1-12, however alleles representing the core mini-haplotype were also detected in population matched controls. The most likely location of the responsible gene within the disease interval, and estimated mutational age, were inferred by linkage disequilibrium mapping (DMLE+2.3). The appearance of a disease-causing mutation was dated between 64-133 generations. The inferred ancestral locus carrying a PPCD1 disease-causing variant within the disease interval spans 60 Kb on 20p11.23, which contains a single known protein coding gene, ZNF133. However, direct sequence analysis of coding and untranslated exons did not reveal a potential pathogenic mutation. Microdeletion or duplication was also excluded by comparative genomic hybridization using a dense chromosome 20 specific array. Geographical origin, haplotype and statistical analysis suggest that in 14 unrelated families an as yet undiscovered mutation on 20p11.23 was inherited from a common ancestor. Prevalence of PPCD in the Czech Republic appears to be the highest worldwide and our data suggests that at least one other novel locus for PPCD also exists.
PLoS ONE 01/2012; 7(9):e45495. · 4.09 Impact Factor
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ABSTRACT: Posterior polymorphous corneal dystrophy (PPCD) is a rare, bilateral autosomal dominant disorder affecting primarily the corneal endothelium and descemet membrane (DM). The aim of this study was to establish the origin of abnormal endothelium in a patient with PPCD exhibiting cornea graft failure after keratoplasty surgery. A sex-mismatched graft obtained from a patient with PPCD who underwent repeat penetrating keratoplasty and the patient's original cornea were investigated. Combined fluorescent immunohistochemistry for cytokeratin (CK) 19 (a marker of aberrant PPCD endothelium) with fluorescence in situ hybridization (FISH) of the sex chromosomes were used in order to characterize the cells on the posterior graft surface. The pathological endothelium of the failed PPCD cornea revealed strong positivity for CK19 using fluorescent immunohistochemistry. In all the CK19-positive cells, both X and Y chromosomes were simultaneously detected using FISH. The results clearly showed the original cells of the patient (XY), within 3.5 years, almost totally overgrown the posterior corneal surface of the graft (XX). Moreover, an abnormal posterior collagenous layer populated by fibroblast-like cells was observed between DM and the endothelium in the failed graft, but its exact origin could not be established due to the low number of cells. Simultaneous detection of CK19 using fluorescent immunohistochemistry together with the detection of gonosomes using FISH was performed for the first time in the cornea and allowed us to prove that the recurrence of PPCD was caused by pathological abnormal proliferation and migration of recipient cells into donor graft.
Histochemie 06/2011; 136(1):93-101. · 2.59 Impact Factor
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ABSTRACT: Limbal transplantation or limbal stem cell (LSC) transfer represents the only way to treat severe ocular surface damage or LSC deficiency. However, limbal allografts are promptly rejected in spite of extensive immunosuppressive therapy. To characterize immune response after limbal transplantation, we established an experimental model of limbal transplantation in the mouse. Syngeneic, allogeneic and xenogeneic (rat) limbal grafts were grafted orthotopically in BALB/c mice and graft survival was evaluated. The presence of graft donor cells and the expression of IL-2, IL-4, IL-10, IFN-γ and inducible nitric oxide synthase (iNOS) mRNA in the grafts were detected by real-time PCR. While syngeneic grafts survived permanently, allografts were rejected in 9.0±1.8 days and xenografts in 6.5±1.1 days. The manifestation of clinical symptoms of rejection correlated with the disappearance of donor cells in the graft and in the recipient cornea. Intragraft expression of iNOS mRNA and distinct expression patterns of Th1 (IL-2, IFN-γ) and Th2 (IL-4, IL-10) cytokines were detected during rejection of limbal allografts and xenografts. The limbal graft rejection was prevented with anti-CD4, but not anti-CD8 monoclonal antibody therapy. The results indicate that limbal grafts do not enjoy immune privilege of the eye and are promptly rejected by Th1 (allografts) or by a combined Th1 and Th2 (xenografts) type of immune response involving CD4+ cells and iNOS expression. Targeting this pathway may be an effective way to prevent and treat limbal graft rejection.
Transplant Immunology 04/2011; 24(3):189-94. · 1.46 Impact Factor
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ABSTRACT: To describe the ocular features of 6 Czech and British patients with posterior polymorphous corneal dystrophy (PPCD) caused by mutations in the zinc finger E-box binding homeobox 1 gene (ZEB1).
Case note review of 4 individuals with p.E776fs mutation, one with p.Y719X and one with p.F375fs mutation within the ZEB1 gene.
Five individuals exhibited endothelial and Descemet membrane changes consistent with the diagnosis of PPCD. We concluded that one 70-year-old female who had a normal endothelium at both slit lamp and non-contact specular microscopy was a case of non-penetrance. The onset of disease was as early as 3 months after birth. One patient had irregular astigmatism with inferior corneal steepening on videokeratography, but without corneal thinning or other signs of keratoconus. Two others had corneal steepening >49D but with regular astigmatism. Three individuals underwent penetrating keratoplasty (PK) in 1 eye, with one patient treated for secondary glaucoma prior to the PK.
The phenotype associated with changes in the ZEB1 gene exhibits variable expression and incomplete penetrance and seems to have a low risk for secondary glaucoma or the need for keratoplasty compared to PPCD linked to 20p11.2. There is insufficient data for phenotype correlations with PPCD caused by other genes.
Ophthalmic Genetics 12/2010; 31(4):230-4. · 0.93 Impact Factor
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ABSTRACT: To investigate the contribution of matrix metalloproteinases (MMPs) to recurrent corneal melting in keratoconjunctivitis sicca associated with primary Sjörgen's syndrome (pSS).
One native melted cornea and ten melted corneal grafts from two patients with severe pSS were used. The presence of MMPs (1, 2, 3, 7, 8, 9, and 13) was detected using indirect enzyme immunohistochemistry. The active forms of MMP 2 and 9 and MMP 3 and 7 were examined by gelatin and casein zymography, respectively. The concentrations of active MMP 1 were measured using an activity assay. Eleven unaffected corneas served as controls.
The average values of the staining intensity revealed very intense MMP 1, intense MMP 2, 7, and 9 and moderate MMP 3 and 8 positivity, in the corneal epithelium of melted corneas. Intense MMP 1 and 9 staining, moderate MMP 2, 3, and 8 staining, and weak MMP 7 staining were found in the anterior stroma. The posterior stroma revealed intense MMP 1, moderate MMP 3 and 9, and weak MMP 2, 7, and 8 positivity. Immunostaining of the endothelium was moderate for MMP 9 and weak for MMP 1, 2, 3, 7, and 8. MMP 13 was negative in all but four melted specimens, where weak-to-moderate staining was found in the epithelium and stroma. Control corneas revealed moderate MMP 1 and 2 and weak MMP 8 staining in the epithelium, weak MMP 2 staining in the anterior stroma, and weak MMP 1 and 8 staining in the endothelium. Significantly elevated MMP 1 activity and extremely elevated MMP 9 activity were found in most of the tested pathological specimens, compared to healthy controls, where no activity of the two enzymes was present. Markedly elevated MMP 2 activity was found in 2 of 11 specimens, compared to normal tissue. The inactive form of MMP 3 was detected in half of the tested specimens, and inactive MMP 7 in all melted corneas. Active MMP 3 and 7 were found in one melted sample. Neither of these MMPs was found in any of the control specimens.
The increased expression and elevated activity of a wide range of MMPs in melted cornea samples from two patients diagnosed with pSS confirm that these enzymes contribute to the tissue destruction, leading to serious consequences such as corneal perforation and loss of vision.
Molecular vision 01/2009; 15:2364-72. · 2.20 Impact Factor
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ABSTRACT: To detect and isolate cells with stem cell (SC) characteristics in the limbus of the mouse.
Limbal tissues from BALB/c mice were trypsin-dissociated and separated on the gradient Percoll (Fluka, Buchs, Switzerland). Several fractions were isolated and characterized by real-time PCR for the presence of limbal SC markers and differentiation markers of corneal epithelial cells by flow cytometry for the determination of the side-population (SP) phenotype and growth properties in vitro.
Cells retained in the lightest fraction (40% Percoll) and in the densest fraction (80% Percoll) of the gradient were both enriched for populations with a high expression of the SC markers ABCG2 and Lgr5 and also expressing the SP phenotype. However, the lightest fraction (representing approximately 12% of total limbal cells) contained cells with the strongest spontaneous proliferative capacity and expressed the corneal epithelial differentiation marker K12. In contrast the densest fraction (<7% of original cells) was K12 negative and contained small nonspontaneously proliferating cells, which instead were positive for p63. Unexpectedly, cells from this fraction had the highest proliferative activity when cultured on a 3T3 feeder cell monolayer.
These findings demonstrate the presence of two distinct populations of corneal epithelial cells with limbal SC characteristics, based on differential expression of the keratin-specific marker K12 and transcription factor p63, and suggest a difference in developmental stage of the two populations, with the K12(-)p63(+) population being closer to the primitive limbal SC.
Investigative ophthalmology & visual science 06/2008; 49(9):3903-8. · 3.43 Impact Factor
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ABSTRACT: To evaluate mutations in the transforming-growth-factor-beta-induced (TGFBI) gene in patients of Czech origin with autosomal dominant corneal dystrophies.
The coding sequence of the TGFBI gene was analysed in 22 affected Czech individuals from 7 apparently unrelated families. Comparison of phenotype to genotype was performed.
A H626P mutation, previously only described in a family with a variant of lattice corneal dystrophy (LCD), was detected in one family with superficial geographic corneal opacities. Light microscopy of 2 samples obtained following either a prior superficial keratectomy or keratoplasty showed amyloid but no fuchsinophilic deposits. In a family with LCD type I, an R124C mutation was identified. The R124L mutation was shown to be causative of Reis-Bucklers corneal dystrophy in 2 families. A family with Thiel-Behnke corneal dystrophy exhibited an R555Q mutation. In 2 families with granular corneal dystrophy type I, the typical R555W change was identified.
The phenotype of the family with the H626P mutation differed from the phenotype previously reported for this change.
Ophthalmic Research 02/2008; 40(2):105-8. · 1.56 Impact Factor
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ABSTRACT: Understanding xenograft rejection is crucial for the potential introduction of xenotransplantation into clinical practice. Small-animal models play an essential role in this context and substantially contribute to our knowledge about mechanisms of xenograft rejection.
Rat-to-mouse corneal xenografts were performed by using 2 suturing techniques. Sutures were left either as long or as short as possible to limit the extent of a nonspecific inflammatory response. Cyclosporine A (CsA), monoclonal antibody anti-T cells, and a specific inhibitor of inducible NO synthase (alone or in a combination with CsA) were tested as immunosuppressants.
Grafts with long sutures were rejected in 7.3 +/- 1.2 days, whereas those with short sutures were rejected after 11.8 +/- 1.0 days (P < 0.001). Similarly, long sutures induced more pronounced corneal neovascularization (P < 0.001). Although groups of recipients with long sutures all tested immunosuppressants significantly (P < 0.01-0.001) prolonged corneal graft survival, none of them showed a comparable efficacy in groups of recipients with short sutures.
This study showed that suturing technique significantly affects the outcome of corneal concordant xenograft transplantation, influences the effectiveness of immunosuppressive regimens, and therefore must be taken into account when evaluating their efficacy.
Cornea 11/2007; 26(9):1111-4. · 1.73 Impact Factor
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Petra Liskova,
Stephen J Tuft,
Rhian Gwilliam,
Neil D Ebenezer,
Katerina Jirsova,
Quincy Prescott,
Radka Martincova,
Marike Pretorius,
Neil Sinclair,
David L Boase,
Margaret J Jeffrey,
Panos Deloukas,
Alison J Hardcastle, Martin Filipec,
Shomi S Bhattacharya
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ABSTRACT: We describe the search for mutations in six unrelated Czech and four unrelated British families with posterior polymorphous corneal dystrophy (PPCD); a relatively rare eye disorder. Coding exons and intron/exon boundaries of all three genes (VSX1, COL8A2, and ZEB1/TCF8) previously reported to be implicated in the pathogenesis of this disorder were screened by DNA sequencing. Four novel pathogenic mutations were identified in four families; two deletions, one nonsense, and one duplication within exon 7 in the ZEB1 gene located at 10p11.2. We also genotyped the Czech patients to test for a founder haplotype and lack of disease segregation with the 20p11.2 locus we previously described. Although a systematic clinical examination was not performed, our investigation does not support an association between ZEB1 changes and self reported non-ocular anomalies. In the remaining six families no disease causing mutations were identified thereby indicating that as yet unidentified gene(s) are likely to be responsible for PPCD.
Human Mutation 07/2007; 28(6):638. · 5.69 Impact Factor
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ABSTRACT: Corneal allograft rejection is frequently studied in small rodent or rabbit models. To study mechanisms of rejection in a model that more closely mimics transplantation in humans, we performed orthotopic corneal transplantation in the miniature pig using a 7-mm diameter donor graft. Four groups of recipients were studied: 1) untreated naive, 2) untreated vascularized (high risk), 3) high-risk grafts treated by topical application of prednisolone, or 4) high-risk grafts treated with a combined systemic immunosuppression regime of oral prednisone, cyclosporine A, and mycophenolate mofetil. Both the clinical features and histological assessment of corneal graft rejection showed close similarities to graft rejection in humans. Interestingly, preliminary results indicated that topical steroid treatment was superior to systemic immunosuppression in significantly promoting graft survival. Thus, corneal transplantation in the pig represents an animal model most closely resembling corneal grafting in humans, and offers possibilities for testing various clinically applicable immunosuppressive treatments.
Transplantation 06/2007; 83(10):1401-3. · 4.00 Impact Factor
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ABSTRACT: Posterior polymorphous corneal dystrophy (PPCD) is a hereditary bilateral disorder affecting Descemet's membrane and the endothelium. The aim of the present study was to determine the spectrum of cytokeratin (CK) expression in cells on the posterior surface of the cornea in PPCD patients. Ten corneal buttons and one specimen of the trabecular meshwork (TM) from PPCD patients who underwent graft or glaucoma surgery were used, as well as six corneal buttons and two TM specimens obtained from healthy donors as controls. Cryosections were fixed and indirect immunofluorescent staining was performed using antibodies directed against a wide spectrum of cytokeratins (CKs). The number of positive cells and the intensity of the staining were assessed using fluorescent microscopy. All 10 PPCD corneal specimens had areas of endothelium displaying typical endothelial morphology as well as areas consisting of layers two to six cells thick with both flat endothelial-like cells and polygonal cells with round nuclei and a large cytoplasm. Both of these morphologically distinct cell types showed strong immunostaining for CK7, CK19, CK8 and CK18, while weaker positive signals were observed for CK1, CK3/12, CK4, CK5/6, CK10, CK10/13, CK14, CK16 and CK17. PPCD endothelium was completely negative for CK2e, CK9, CK15, and CK20. Focal positivity was detected in PPCD TM for CK4, CK7 and CK19. CK8 and CK18 were the only CKs expressed in control endothelium. PPCD and control epithelium displayed similar staining patterns. The distinct positivity for CK3/12, CK4, CK5/6, CK10/13, CK14, CK16 and CK17 was observed in aberrant PPCD endothelium for the first time. We demonstrate that the abnormal endothelium of PPCD patients expresses a mixture of CKs, with CK7 and CK19 predominating. In terms of CK composition, the aberrant PPCD endothelium shares features of both simple and squamous stratified epithelium with a proliferative capacity. The wide spectrum of CK expression is most probably not indicative of the transformation of endothelial cells to a distinct epithelial phenotype, but more likely reflects the modified differentiation of metaplastic epithelium.
Experimental Eye Research 05/2007; 84(4):680-6. · 3.26 Impact Factor
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ABSTRACT: To confirm and define a molecular basis for a case of mucolipidosis type IV (ML IV) with an extremely atypical phenotype pattern.
Observational case report of a patient with ML IV with disease progression restricted to ocular symptoms.
Complete ophthalmologic and neurologic examination. Ultrastructural examination of white blood cells, skin, conjunctiva, and corneal epithelium. The MCOLN1 gene was sequenced from cDNA and the proportion of splicing variants were assessed by quantitative allele-specific polymerase chain reaction.
Absence of any neurological abnormalities. Retinal pathologic features were the main cause of visual disability: low visual acuity and cloudy corneas since 2 years of age, progressive decrease in visual acuity since the age of 9 years. Ultrastructural examination showed storage lysosomes filled with either concentric membranes or lucent precipitate in corneal and conjunctive epithelia and in vascular endothelium. Cultured fibroblasts were free of any autofluorescence. Sequencing of the MCOLN1 gene identified compound heterozygosity for D362Y and A-->T transition leading to the creation of a novel donor splicing site and a 4-bp deletion from exon 13 at the mRNA level. Both normal and pathologic splice forms were detected in skin fibroblasts and leukocytes, with the normal form being more abundant.
The case of this patient with ML IV is unique and is characterized by a curious lack of generalized symptoms. In this patient, the disorder was limited to the eyes and appeared without the usual psychomotor deterioration. The resulting phenotype is the mildest seen to date.
American Journal of Ophthalmology 05/2007; 143(4):663-71. · 4.22 Impact Factor
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Rhian Gwilliam,
Petra Liskova, Martin Filipec,
Stanislav Kmoch,
Katerina Jirsova,
Elizabeth J Huckle,
Catherine L Stables,
Shomi S Bhattacharya,
Alison J Hardcastle,
Panos Deloukas,
Neil D Ebenezer
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ABSTRACT: Posterior polymorphous corneal dystrophy (PPCD) is an autosomal dominant disorder, affecting both the corneal endothelium and Descemet's membrane. In the Czech Republic, PPCD is one of the most prevalent corneal dystrophies. The purpose of this study was to determine the chromosomal locus of PPCD in two large Czech families, by using linkage analysis.
Linkage analysis was performed on 52 members of two Czech families with PPCD and polymorphic microsatellite markers and lod scores were calculated. The candidate gene VSX1 was also screened for mutations.
Significant lod scores were obtained with microsatellite markers on chromosome 20. Linkage analysis delineated the Czech PPCD locus to a 2.7-cM locus on chromosome 20, region p11.2, between flanking markers D20S48 and D20S139, which excluded VSX1 as the disease-causing gene in both families. In addition, the exclusion of VSX1 was confirmed by sequence analysis.
This study reports the localization of PPCD in patients of Czech origin to chromosome 20 at p11.2. Linkage data and sequence analysis exclude VSX1 as causative of PPCD in two Czech families. This refined locus for PPCD overlaps the congenital hereditary endothelial dystrophy (CHED1) disease interval, and it is possible that these corneal dystrophies are allelic.
Investigative Ophthalmology & Visual Science 01/2006; 46(12):4480-4. · 3.60 Impact Factor
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ABSTRACT: The effects of passive transfer of antisera containing cytotoxic antibodies to allo- and xenoantigens on survival of corneal allografts and xenografts were evaluated in experimental models. Corneas from allogeneic B10 or xenogeneic rat Lewis donors were grafted orthotopically into BALB/c mice. Recipient mice were treated with donor-specific antisera administered at the period of grafting or at 2 weeks after transplantation. Rejection was determined by the severity of corneal opacity using a standard scoring system. Treatment of graft recipients with donor-specific antisera accelerated the onset of graft rejection and significantly shortened survival times of both corneal allografts and xenografts. Corneal xenografts, which had been accepted after treatment with anti-CD4 monoclonal antibody, were acutely rejected by the passive transfer of antiserum against xenoantigens. The results suggest that corneal grafts are vulnerable to antibody-dependent immunity and that cytotoxic antibodies against graft donor antigens can mediate rejection of both corneal allografts and xenografts.
Immunology Letters 10/2005; 100(2):211-3. · 2.53 Impact Factor
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ABSTRACT: Corneal xenotransplantation may be an alternative approach to overcome shortage of allografts for clinical transplantation. Orthotopic corneal rat-to-mouse xenotransplantation and syngeneic transplantation was performed and the effects of anti-CD4 and anti-CD8 treatments on corneal xenograft survival and production of cytokines, interleukin (IL)-2, IL-4, IL-10, gamma-interferon (IFN-gamma) and nitric oxide (NO) were evaluated. RT-PCR was used to determine the expression of genes for cytokines and inducible nitric oxide synthase (iNOS) in the grafts. The presence of iNOS protein in grafts was detected by immunofluorescent staining. We found that corneal xenotransplantation was associated with a strong upregulation of genes for both Th1 and Th2 cytokines and with NO production in the graft. Treatment of xenograft recipients with mAb anti-CD4, but not anti-CD8, resulted in a profound inhibition of IL-2, IL-4 and IL-10 production, and in a significant prolongation of corneal xenograft survival. The results show that upregulation of Th2 cytokines after corneal xenotransplantation does not correlate with xenograft rejection. Rather, corneal graft rejection is associated with the expression of genes for IFN-gamma and iNOS and with NO production.
Transplant International 08/2005; 18(7):854-62. · 2.92 Impact Factor
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ABSTRACT: : Currently, there are no effective treatments for the control of corneal xenograft rejection. We evaluated the efficacy and mode of action of a novel immunosuppressant, FTY720, in a model of corneal xenograft transplantation.
: Rat-to-mouse corneal xenografts were performed and the effects of treatment with daily intraperitoneal injections of FTY720 (0.5 or 3.0 mg/kg/day) or saline from 2 days pretransplantation were assessed clinically. Immunohistochemical studies of the grafts and flow cytometry of the draining lymph node subpopulations were performed at the time of clinical rejection.
: Treatment with FTY720 delayed the onset of corneal rejection, from 8 days postgraft in saline-treated mice to 12.0 +/- 0.89 days for low-dose FTY720 treatment and 15.6 +/- 3.1 days for high-dose FTY720 treatment (both P<0.001). Histologically, FTY-treated animals had a markedly reduced inflammatory response in the anterior chamber and cornea after replacement of the xenograft epithelium with normal healthy host epithelium. In contrast, saline-treated xenografts had persisting corneal epithelial defects and ulceration. In the draining lymph nodes, FTY720 not only inhibited the increase in the cell number observed in saline-treated recipients of xenografts, but also reduced the expression of activation markers on B cells (MHC class II and CD86).
: FTY720 treatment significantly delayed rejection and decreased its severity in a dose-dependent manner in a rat-to-mouse model of corneal xenotransplantation. Since corneal xenograft rejection is mediated not by natural antibodies or CD8+ T cells directly, but by CD4+ T cells, the data from these experiments imply that FTY720 mediated its effect via CD4+ T cells.
Transplantation 02/2005; 79(3):297-303. · 4.00 Impact Factor
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ABSTRACT: As shown previously, the submandibular (SM) lymph node (LN) is required for priming the immune response during corneal graft rejection. In this study, we wished to determine whether corneal grafts at "high-risk" of rejection were also protected after selective SM LN removal and if so to investigate whether this improved corneal graft survival was due to induction of specific regulatory/suppressor cells or was due to immunological "ignorance".
Two sets of experiments were performed. (1) Adoptive transfer of possible regulatory splenocytes from mice with long-term accepted corneal graft after SM LN removal. (2) SM LN removal and corneal grafts in "high-risk" hosts, which had been (A) subjected to corneal trauma with vascularization or (B) allosensitized by previous corneal graft or (C) allosensitized by previous skin graft.
Adoptive transfer of splenocytes from tolerant mice after SM LN removal did not enhance corneal graft survival in naive recipients (p > 0.05). SM LN removal in mice with corneal vascularization enhanced corneal allograft survival compared to grafted controls with/without vascularization (p < 0.0001). The removal of the SM LN in mice, who had already been allosensitized by a previous corneal graft, did not statistically prolong corneal graft survival (p > 0.05). SM LN removal procedure did not delay rejection of corneal grafts in mice allosensitized by a previous skin transplant with the same strain combination (p > 0.05).
The results suggest that removal of the SM LN in "high-risk" mice prevents rejection by mechanisms involving immune "ignorance", since prior allosensitization prevents graft acceptance after LN removal. In allosensitized recipients the stronger the allosensitization (skin- vs. corneal graft-presensitization) the greater the possibility of priming for rejection at alternative draining LN sites.
BMC Ophthalmology 01/2004; 4:3. · 1.00 Impact Factor
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ABSTRACT: Abstract
Background
As shown previously, the submandibular (SM) lymph node (LN) is required for priming the immune response during corneal graft rejection. In this study, we wished to determine whether corneal grafts at "high-risk" of rejection were also protected after selective SM LN removal and if so to investigate whether this improved corneal graft survival was due to induction of specific regulatory/suppressor cells or was due to immunological "ignorance".
Methods
Two sets of experiments were performed. (1) Adoptive transfer of possible regulatory splenocytes from mice with long-term accepted corneal graft after SM LN removal. (2) SM LN removal and corneal grafts in "high-risk" hosts, which had been (A) subjected to corneal trauma with vascularization or (B) allosensitized by previous corneal graft or (C) allosensitized by previous skin graft.
Results
Adoptive transfer of splenocytes from tolerant mice after SM LN removal did not enhance corneal graft survival in naive recipients (p > 0.05).
SM LN removal in mice with corneal vascularization enhanced corneal allograft survival compared to grafted controls with/without vascularization (p < 0.0001). The removal of the SM LN in mice, who had already been allosensitized by a previous corneal graft, did not statistically prolong corneal graft survival (p > 0.05). SM LN removal procedure did not delay rejection of corneal grafts in mice allosensitized by a previous skin transplant with the same strain combination (p > 0.05).
Conclusion
The results suggest that removal of the SM LN in "high-risk" mice prevents rejection by mechanisms involving immune "ignorance", since prior allosensitization prevents graft acceptance after LN removal. In allosensitized recipients the stronger the allosensitization (skin- vs. corneal graft-presensitization) the greater the possibility of priming for rejection at alternative draining LN sites.
BMC Ophthalmology. 01/2004;
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ABSTRACT: Recent studies have shown that head-neck draining lymph nodes (DLN) are required for priming the immune response during corneal allograft rejection. In this study we have investigated further the role of the DLN and spleen in corneal graft rejection in mice.
Individual DLN (submandibular [SM]; superficial cervical [SC]; and internal jugular) or their combinations were removed in mice undergoing corneal allografting (C57BL/10, H2(b) to BALB/c, H2(d)). In some mice, DLN from syngeneic mice were retransplanted, whereas other mice underwent removal of the spleen before corneal allografting. In a high-risk group of mice, removal of the DLN before a second corneal graft procedure was performed.
The data show that a single specific lymph node, i.e., the SM node, is the major DLN involved in corneal graft rejection whereas its nearest neighbor, the SC DLN, not only cannot substitute for the SM node in priming the immune response but may be involved with the spleen in immune privilege. Retransplantation studies of syngeneic LN indicate that the site of the DLN is more important to the process of graft rejection than the specific DLN tissue. This applies to the DLN whether it contains naive or memory allospecific T cells as shown in experiments in which removal of the SM DLN from mice who had already been primed by a previous corneal graft, prevented rejection of a second corneal graft in the same strain combination.
Transplantation 02/2002; 73(2):210-5. · 4.00 Impact Factor
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ABSTRACT: To evaluate the number of micronuclei in snake-like chromatin (SLC) cells in the conjunctival epithelium of keratoconjunctivitis sicca (KCS) patients. To elucidate possible correlations between SLC cell numbers and KCS intensity.
Impression cytology specimens from the bulbar conjunctiva of healthy controls and KCS patients were harvested and divided into 3 groups: group 1, controls; group 2, KCS SLC-negative; and group 3, KCS SLC-positive. The number of micronuclei (MNi) in SLC-negative and SLC-positive epithelial cells of each group was counted.
The number of MNi in SLC-negative cells of groups 1 and 2 did not exceed 1 MNi/1,000 cells. A significant increase in the frequency of micronuclei in the upper bulbar conjunctiva was noted in SLC-positive (14.75 +/- 8.09 MNi/1,000 cells) as well as SLC-negative cells (4.0 +/- 3.83 MNi/1,000 cells) of group 3.
We demonstrate here that the presence of MNi in the conjunctival epithelium of KCS patients could be a characteristic feature accompanying SLC cells. The fact that increased numbers of SLC cells correlates with impaired values in clinical test as well as decreased goblet and epithelial cell densities confirms that the presence of SLC cells correlates with KCS intensity.
Acta cytologica 51(4):541-6. · 0.49 Impact Factor
