Role of enhanced expression of m-CSF in conjunctiva affected by cicatricial pemphigoid

PURPOSE: Local proliferation of macrophages has been reported to augment the inflammatory response in various human and experimental diseases. Macrophage accumulation in the submucosa is also an important feature in the pathogenesis of ocular cicatricial pemphigoid (OCP). In the present study, the role of local proliferation of macrophages in conjunctiva affected by OCP and the relationship between local proliferation of macrophages and expression of macrophage-colony-stimulating factor (m-CSF) in such conjunctiva were examined. METHODS: Biopsy specimens from the conjunctiva of 10 untreated patients with active OCP and from 5 normal subjects were studied for the expression of m-CSF, macrophages, and proliferating cell nuclear antigen (PCNA), a cell cycle protein, by immunohistochemistry. Dual staining for CD68 (a cell surface marker for macrophages) and PCNA was also performed to identify proliferating macrophages. In addition, fibroblasts isolated from conjunctiva of normal individuals and from patients with OCP were studied for the expression of m-CSF by immunostaining and real-time PCR. To identify the factors that induce m-CSF in conjunctival fibroblasts, the fibroblasts were incubated with different concentrations of interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha, and the levels of m-CSF mRNA were determined by real-time PCR and the amount of m-CSF produced was determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Normal conjunctiva showed weak expression of m-CSF in the conjunctival epithelial cells and stroma. Conjunctival expression of m-CSF protein was significantly (P < 0.0001) increased in conjunctival biopsy specimens from patients with OCP. m-CSF was detected in the infiltrating macrophages, stromal cells (presumably fibroblasts), and conjunctival epithelial cells. Compared with normal control conjunctival tissue, a 1.2-fold increase in the expression of mRNA for m-CSF was detected by real-time PCR in the conjunctival tissue obtained from patients with OCP. Increased expression of m-CSF correlated significantly (P < 0.0004) with an increased stromal accumulation of macrophages in conjunctival biopsy specimens of patients with OCP. A number of these accumulated macrophages (CD68-positive) were found to be proliferating (PCNA-positive). In addition, fibroblasts isolated and cultured from conjunctiva of patients with OCP showed significantly increased (1.7-fold) expression of m-CSF compared with normal conjunctival fibroblasts. When conjunctival fibroblasts were treated with IL-1alpha or TNF-alpha, real-time PCR and ELISA detected an increased level of m-CSF. CONCLUSIONS: An increased expression of m-CSF was observed in conjunctiva from patients with active OCP. There was a positive correlation between expression of m-CSF and accumulation of macrophages in conjunctival biopsy sections obtained from patients with OCP. Increased expression of m-CSF, mainly by conjunctival fibroblasts and infiltrating inflammatory cells, may play an important role in the regulation of local proliferation of macrophages in OCP. In the conjunctiva of patients with OCP, this process could augment or enhance the local inflammatory response and tissue injury consequent to it.     

A current appreciation of sites for pharmacological intervention in allergic conjunctivitis: effects of new topical ocular drugs.

Two important realizations about pathophysiological mechanisms involved in allergic conjunctivitis have led to novel drug discovery efforts and new topical ocular medications for prevention and treatment of this prevent allergic disease. The first of these, interspecies and intraspecies mast cell heterogeneity, was established in the mid-1980's by investigators working in the field of asthma. It is now appreciated that secretory responses as well as effects of pharmacological agents differ depending upon the mast cell population studied. Two types of human mast cells, the tryptase containing (T) and the tryptase/chymase containing (TC) mast cells, have been characterized in a variety of tissues. Significantly, Irani et al. (1) demonstrated by immunohistochemical staining that the mast cells present in conjunctival tissues from patients with allergic conjunctivitis were 100% TC. Functional responses of human conjunctival mast cells to a variety of secretagogues (2) were consistent with their classification as TC or connective tissue type mast cells. Importantly, the studies by Miller et al. mentioned above allowed the harvesting and preparation of human conjunctival mast cells for use in drug screening studies. Utilization of these cells has led to the identification of Patanol, the most effective human conjunctival mast cell stabilizer available for topical use in allergic conjunctivitis (3). These same studies demonstrated the lack of mast cell stabilizing activity for cromolyn and nedocromil in these connective tissue type, TC containing, human conjunctival mast cells. Similar lack of effect was noted with these drugs on human skin mast cell degranulation (4). The second important discovery in the area of allergic conjunctivitis has been the demonstration that conjunctival epithelial cells may contribute to the perpetuation of the allergic response. A report from Gamache et al. (5) identified cytokines produced by human conjunctival epithelial cells following treatment with a number of stimuli. Significantly, Sharif et al. (6) subsequently identified functional histamine H1 receptors on these same cell types. Recently, Weimer et al. (7) have shown that exposure of human conjunctival epithelial cells to histamine leads to the production of pro-inflammatory cytokines IL-6 and IL-8. Importantly, treatment of the epithelial cells with drugs that possess histamine H1 antagonist properties prevents cytokine production. It is noteworthy that first generation anti-histamines antazoline and pheniramine are not potent inhibitors of histamine-stimulated cytokine synthesis in intact epithelial cells, while newer anti-histamines Emadine and levocabastine are more potent. Surprisingly, Patanol was more potent as an inhibitor of histamine-stimulated cytokine production by the epithelial cells than would be predicted from its histamine H1 antagonist affinity. These inhibitory effects on conjunctival epithelial cell production of pro-inflammatory cytokines may contribute to enhanced clinical activity noted with these recently approved drugs.     

The relation between expression of basic fibroblast growth factor and mast cells in pterygium

OBJECTIVE: To examine the expression and distribution of basic fibroblast growth factor (bFGF) and mast cells in pterygium, and evaluate its effects in the pterygium formation and progression. METHOD: The expression of bFGF and mast cell tryptase in 17 primary pterygia, 6 recurrent pterygia and 6 normal conjunctival specimens were studied. The mast cell count and bFGF expression situation were observed. RESULTS: The bFGF was specifically localized in the epithelium, blood vessels and a subset of connective tissue cells. The bFGF expression was increased in the recurrent pterygium. The numbers of infiltrating mast cells (five 400 x sights) were (45.47 +/- 5.50) cells and (48.83 +/- 3.19) cells in the primary and recurrent pterygium respectively. In the comparisons between the cells in the pterygium (primary and recurrent) and (4.24 +/- 2.36) cells in the normal connective tissue, there were significant differences (F = 200.3128; q = 26.6762, 23.7341; P < 0.05). The shape and distribution of all the tryptase-positive cells (mast cells) in the pterygium tissues were similar to that of the cells with bFGF expression in the connective tissue. And the majority of bFGF-positive cells (87.54 +/- 3.60)% were similar to that of mast cells in the connective tissue. CONCLUSIONS: All infiltrating mast cells in pterygium have bFGF-positive expression. The bFGF expression is increased in the epithelium, blood vessels and infiltrating mast cells of the pterygium, and may contribute to the formation and progression of a pterygium.     

Conjunctival resection combined with tenon layer excision and the involvement of mast cells in superior limbic keratoconjunctivitis

PURPOSE: To evaluate the effectiveness of conjunctival resection combined with Tenon layer excision in treating superior limbic keratoconjunctivitis (SLK) and the involvement of mast cells in SLK. DESIGN: Retrospective, interventional case series. METHODS: Forty eyes of 30 SLK patients who were unresponsive to medical treatment received superior bulbar conjunctival resection, and another 20 patients who underwent cataract and retinal surgery served as a control group. The conjunctiva specimens from study and control patients were examined by hematoxylin and eosin staining and immunohistochemistry using antibodies against mast cell tryptase. RESULTS: In all operated eyes, the clinical symptoms and signs, including irritation and redness and superior bulbar conjunctival hyperemia and superior tarsal conjunctival papillary hypertrophy, subsided significantly three months after the operation. Only three eyes had recurrence from the margin of conjunctival resection, and this was relieved after reoperation. Keratinized conjunctival epithelium, loss of goblet cells, and increased mast cell numbers (P<.05) were found in the SLK group. CONCLUSIONS: Our cases demonstrate that superior bulbar conjunctival resection combined with Tenon layer excision is an effective treatment for SLK. The pathologic findings suggest that mast cells may play a role in the pathogenesis of SLK.     

Immunophenotypic analysis of the inflammatory infiltrate in ocular cicatricial pemphigoid. Further evidence for a T cell-mediated disease

Ocular cicatricial pemphigoid (OCP) is characterized by the deposition of immunoglobulin and complement along the conjunctival epithelial basement membrane zone (BMZ). In order to further elucidate the cellular populations of the local inflammatory infiltrates, the authors used a panel of monoclonal antibodies in cryostat tissue sections to delineate T cell subsets, B lymphocytes, dendritic cells, and macrophages in six patients with OCP. In comparison with matched controls of the epibulbar conjunctiva, the authors discovered a threefold increase in T lymphocytes within the epithelium and a 20-fold increase within the substantia propria. In contrast with the normal-standing population of conjunctival T lymphocytes, there were activated interleukin 2 receptor (IL-2R)-positive lymphocytes in both the epithelium and the substantia propria. Macrophages were the second most common cells in the substantia propria, accounting for 12.7% of the mononuclear population--a threefold increase over the normal percentage. B cells and plasma cells, normally absent from epibulbar conjunctiva, were the next most prominent populations, constituting 6.9 and 4.6%, respectively, of all mononuclear cells. Dendritic cells which process antigen locally constituted only 1.2% of the mononuclear cell population, but were increased 25-fold over normal controls. By elaborating cytokines that promote fibroplasia, the T cells in OCP may be effector cells along with macrophages and other inflammatory cells in bringing about scarification of the substantia propria, and may furthermore be responsible for an immunoregulatory defect that allows local B lymphocytes to produce autoantibodies to the BMZ.     

Mast cells in pterygium: number and phenotype.

PURPOSE: To investigate the pathogenesis of pterygium. METHODS: The number and phenotype of mast cells were examined in excised tissue from 35 pterygia patients and compared with those in normal conjunctival specimens obtained during cataract or other intraocular surgery. RESULTS: Toluidine blue staining showed that the mean number of mast cells in the pterygia specimens was twice as high as that in the normal conjunctival tissues. Immunohistochemistry with a primary antibody to tryptase, specific for mast cells, also revealed a twofold increase in the mast cell number in the pterygia specimens compared with the normal conjunctival tissues. In the pterygia, more than 94% of the tryptase-positive mast cells were found to express chymase and c-kit. Almost all mast cells in the pterygia were tryptase-positive, chymase-positive mast cells (MC(TC)S). There was no phenotypic difference between the mast cells in the pterygia and those in the normal conjunctival tissues. CONCLUSIONS: The MC(TC)S appear not to be immune system-related and to have functions in angiogenesis and tissue remodeling. The increase in the number of mast cells caused by nonallergic stimulation may contribute to the pathogenesis of pterygium.     

Effects of IL-4 on conjunctival fibroblasts: possible role in ocular cicatricial pemphigoid

PURPOSE: Increased stromal accumulation of macrophages and submucosal fibrosis due to excessive accumulation of collagens are central histologic features in ocular cicatricial pemphigoid (OCP). Interleukin (IL)-4 plays an important role in both the inflammatory and fibrotic events in several human and experimental diseases. In the present study, the possible role of IL-4 in the pathogenesis of OCP was investigated. METHODS: Biopsy specimens from the conjunctivae of 10 patients with OCP and 5 normal subjects were studied for the expression of IL-4 by immunohistochemistry. The expression level of IL-4 was also examined in conjunctival fibroblasts of normal control subjects and patients with OCP. The effects of IL-4 in the induction of inflammatory and fibrogenic molecules was studied in IL-4-treated conjunctival fibroblasts, and the expression levels of macrophage colony-stimulating factor (m-CSF), heat shock protein (HSP)-47 and type I collagen was determined by quantitative real-time PCR. The level of IL-4 was also measured by enzyme-linked immunosorbent assay (ELISA) in serum samples obtained from patients with OCP during active stage and remission and were compared with the levels in control sera. RESULTS: Compared with the weak expression of IL-4 in the normal conjunctival sections, an increased expression of IL-4 was noted in conjunctival sections of patients with OCP. A similar increase in the expression of IL-4 was also detected in fibroblasts isolated from conjunctiva of patients with OCP, compared with control fibroblasts. Real-time PCR and ELISA detected a significantly increased level of m-CSF, at both the mRNA and protein levels in IL-4-stimulated cells. Similarly, IL-4 treatment resulted in the induction of type I collagen and collagen-binding HSP47 by conjunctival fibroblasts, as detected by real-time PCR. However, no apparent changes in the levels of IL-4 were detected by ELISA in serum samples of patients with OCP and control subjects. CONCLUSIONS: Increased conjunctival expression of IL-4 may play an important role in the regulation of local accumulation of macrophages (by inducing m-CSF), and matrix accumulation (by inducing HSP47 and collagen) during conjunctival scarring in patients with OCP. IL-4, therefore, may augment or enhance both conjunctival inflammatory and subsequent fibrotic responses in patients with OCP.     

Tryptase increases proliferative activity of human conjunctival fibroblasts through protease-activated receptor-2

PURPOSE: Tryptase that is released by mast cell degranulation has recently been thought to play a key role in wound healing in allergic bronchitis. Conjunctival fibroblasts secrete mediators and extracellular matrices that could exacerbate inflammation and papillary formation in allergic conjunctivitis. This study was conducted to investigate the effect of tryptase on the proliferation of conjunctival fibroblasts and studied whether this effect was mediated by protease-activated receptor (PAR)-2. METHODS: Conjunctival fibroblasts were cultured with or without tryptase (0.1 ng/mL to 1.0 microg/mL), and the proliferation rate was assessed after 48 hours. The effects of tryptase inhibitors (leupeptin, benzamidine) and a PAR-2 agonist (SLIGKV) were examined. The existence of PAR-2 mRNA and protein in conjunctival fibroblasts was examined by RT-PCR and Western blot analysis, respectively. The existence of PAR-2 in cultured conjunctival fibroblasts and conjunctival papillae from patients with vernal keratoconjunctivitis, as well as conjunctival tissue from normal subjects was examined by immunohistochemistry. RESULTS: Conjunctival fibroblast proliferation was upregulated by tryptase in a dose-dependent manner (P < 0.001). Leupeptin and benzamidine inhibited tryptase-induced fibroblast proliferation (P < 0.05), and SLIGKV mimicked tryptase's effect. PAR-2 mRNA and protein were detected in cultured conjunctival fibroblasts using RT-PCR and Western blot analysis. PAR-2 immunoreactivity in both the cultured conjunctival fibroblasts and in stromal cells in excised conjunctival tissues was observed. CONCLUSIONS: Tryptase increased conjunctival fibroblast proliferation and this response appeared to be mediated by PAR-2. Mast cells are the most likely source of tryptase in the conjunctiva and may play an important role in chronic exacerbations with conjunctival papillary formation in allergic conjunctivitis.     

The relative contribution of mast cell subsets to conjunctival TH2-like cytokines

PURPOSE: To investigate the distribution of the T-helper (TH)2-like cytokines, interleukin (IL)-4, IL-5, IL-6, and IL-13 between mast cell subsets in conjunctival biopsy specimens from normal subjects and those with seasonal allergic conjunctivitis (SAC) during and outside of the grass pollen season. METHODS: Sequential and double in situ hybridization (ISH) and immunohistochemistry (IHC) were performed on thin sections of human conjunctiva to determine the colocalization of the immunoreactivity of IL-4, IL-5, IL-6, and IL-13 to mast cell subsets in normal subjects and subjects with atopy and to detect IL-4 mRNA in conjunctival mast cells. RESULTS: More than 90% of IL-4+-immunoreactive cells were observed to be mast cells in conjunctival biopsy specimens from all patient groups. The majority of IL-5+, IL-6+, and IL-13+ cells were also noted to be mast cells for each group. IL-4 preferentially colocalized to the tryptase+-chymase+ mast cell phenotype (MC(TC)) with MC(TC) cells comprising 93.3% of cytokine+ mast cells in symptomatic SAC (P = 0.0017), 89.2% in asymptomatic SAC (P = 0.0008), and 77.8% in normal subjects (P = 0.0472). IL-13 appeared to colocalize preferentially to the MC(TC) phenotype and IL-5 and IL-6 to the MC(T) phenotype. ISH showed that 75.8% of mast cells in normal subjects, 78.7% in subjects with symptomatic SAC, and 18.7% in subjects with asymptomatic SAC expressed mRNA for IL-4. CONCLUSIONS: Conjunctival mast cells are an important source of IL-4, IL-5, IL-6, and IL-13 immunoreactivity, with preferential colocalization of IL-4 and IL-13 on the MC(TC) subset and IL-5 and IL-6 to the MC(T) subset. This evidence suggests that differences in protease phenotype may also reflect functional differences evidenced by the different patterns of cytokine distribution.     

Biology of interleukin-5 in ocular cicatricial pemphigoid

BACKGROUND: Ocular cicatricial pemphigoid (OCP) is an autoimmune disease characterized by the presence of autoantibodies, T-cell dysregulation, and abnormal serum levels of cytokines such as interleukin-6, interleukin-1, and tumor necrosis factor-alpha. The purpose of the present study was to investigate levels of interleukin-5 (IL-5) in the sera, eosinophil counts in the peripheral blood, and eosinophil and mast cell counts in the inflamed conjunctivae of patients with active OCP. METHODS: Seven patients diagnosed in the active phase of OCP presenting with chronic cicatrizing conjunctivitis were studied. The serum levels of IL-5 were compared to a group of seven age-, race-, and sex-matched normal human subjects. Eosinophil and mast cell counts in the patients' conjunctivae were compared to those in normal conjunctivae harvested during cataract surgery from seven normal individuals. In addition, eosinophil counts in peripheral blood of patients with active OCP were compared to those in normal individuals. RESULTS: The mean serum level of IL-5 in patients with active OCP was higher (67.23 pg/ml, range 46.33-98.26 pg/ml) than that in normal individuals (12.18 pg/ml, range 7.66-18.86). The difference was statistically significant ( P<0.001). On light microscopy the biopsied conjunctivae stained with hematoxylin and eosin revealed statistically significant differences ( P<0.001) in the mean numbers of eosinophils in the substantia propria between the patients with active OCP (6.8 cells/cm(2), range 4.8-8.2 cells/cm(2)) and normal controls (0.91 cells/cm(2), range 0.4-1.8 cells/cm(2)). The average number of mast cells found in the substantia propria of the biopsied conjunctivae was statistically significantly higher in patients with OCP (13.79 cells/cm(2), range 6.6-19.4) than in normal individuals (4.34 cells/cm(2), range 3.2-7.8; P<0.01). The average number of eosinophils in the peripheral blood of patients with active OCP (6.6x10(7)/l, range 2.9 - 9.3x10(7)/l) was statistically significantly higher ( P<0.01) than in normal controls (2.09x10(7)/l, range 0 - 4.5x10(7)/l). CONCLUSIONS: The results suggest that IL-5 may play an important role in the pathogenesis of OCP.     

Role of macrophage migration inhibitory factor in conjunctival pathology in ocular cicatricial pemphigoid

PURPOSE: Macrophage migration inhibitory factor (MIF) is a pleiotropic, proinflammatory cytokine that mediates various immunoinflammatory processes. Ocular cicatricial pemphigoid (OCP) is an autoimmune disease in which affected conjunctivae show features of an immunoinflammatory disease. In this study, the role of MIF in the pathogenesis of OCP was examined. METHODS: The expression of MIF in conjunctival tissues of patients with OCP (n = 10) and normal subjects (n = 5) was studied by quantitative real-time PCR and immunohistochemistry. The production of MIF by conjunctival fibroblasts of normal control subjects and patients with OCP was determined, by using quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA). In addition, the effects of interleukin (IL)-1, tumor necrosis factor (TNF)-alpha, and transforming growth factor (TGF)-beta1 on the induction of MIF by conjunctival fibroblasts were studied by quantitative real-time PCR. To determine the relationship between conjunctival expression of MIF and accumulation of macrophages, in patients with OCP, a correlation study was performed. RESULTS: An increased conjunctival expression of MIF was detected in patients with OCP, both at the mRNA (by real-time PCR) and protein level (by immunohistochemistry), compared with normal control patients. The expression of MIF was detected in the epithelial cells and occasionally in the stromal cells in control conjunctival tissues, by immunohistochemistry. In contrast, a statistically significant increase (P < 0.0001) in the expression of MIF was detected in the stromal cells of conjunctival tissues obtained from patients with OCP (control: 4.89 +/- 0.5; OCP: 19.82 +/- 1.34). By quantitative real-time PCR, compared with control conjunctiva, an increase in the expression of MIF was detected in the conjunctiva obtained from patients with OCP. A similar increase in the expression of MIF was also detected in conjunctival fibroblasts of patients with OCP, compared with control fibroblasts, by quantitative real-time PCR. A significantly increased (P < 0.001) level of MIF was also detected in supernatant collected from conjunctival fibroblasts of patients with OCP (186 +/- 5.4), compared with supernatant collected from control fibroblasts (9.3 +/- 7.6). Moreover, IL-1, TNF-alpha, and TGF-beta1, known factors involved in the pathogenesis of OCP, were found to induce the expression of MIF by conjunctival fibroblasts. A statistically significant correlation (P < 0.0001, r(2) = 0.4465) was observed between the expression of MIF and accumulation of CD68-positive macrophages in conjunctiva of patients with OCP. CONCLUSIONS: This study demonstrated an increased conjunctival expression of MIF in patients with OCP. MIF may be actively involved in the pathogenesis of OCP, possibly regulating the inflammatory events of the disease process.     

Role of collagen-binding heat shock protein 47 and transforming growth factor-beta1 in conjunctival scarring in ocular cicatricial pemphigoid

PURPOSE: Submucosal fibrosis due to excessive accumulation of collagens is an important histologic feature in the pathogenesis of ocular cicatricial pemphigoid (OCP). Heat shock protein 47 (HSP47), a collagen-binding protein, plays an important role in the biosynthesis of procollagens. In the present study, we examined the role of HSP47 in conjunctival scarring in patients with OCP. METHODS: Biopsy specimens of the conjunctiva of 15 patients with OCP and 5 normal subjects were studied for the expression of HSP47, transforming growth factor (TGF)-beta1, type I collagen, and type III collagen. The role of TGF-beta1 on the induction of HSP47 and type I collagen by conjunctival fibroblasts was studied by immunostaining, Western blot analysis, and quantitative real-time PCR. RESULTS: Compared with the control, increased accumulations of type I and type III collagens were detected by immunohistochemistry in fibrotic conjunctiva of patients with OCP. Weak and sparse expression of HSP47 was detected in the epithelial cells and stromal fibroblasts in control conjunctival tissues. In contrast to the control, the expression of HSP47 was markedly increased in the stromal fibroblasts in conjunctival tissues obtained from patients with OCP, as detected by immunohistochemistry. By quantitative real-time PCR, compared with control conjunctival tissues, a 3.4-fold increase in the expression of HSP47 was noted in the conjunctival tissues obtained from patients with OCP. Similar to conjunctival tissues, fibroblasts isolated from conjunctiva of patients with OCP exhibited 4.8-fold increase in the expression of HSP47, compared with control fibroblasts. When conjunctival fibroblasts were treated with various concentration of TGF-beta1, upregulation in the expression of HSP47 and type I collagen was detected. CONCLUSIONS: This study demonstrated increased expression of HSP47 and TGF-beta1 by conjunctival fibroblasts in biopsy specimens obtained from patients with OCP. TGF-beta1 induced the expression of HSP47 and type I collagen by conjunctival fibroblasts. Increased levels of TGF-beta1 and HSP47 may regulate increased synthesis, assembly, and production of collagens and thereby could significantly contribute to the process of conjunctival scarring in patients with OCP.     

Tumour necrosis factor-alpha in conjunctivae affected by ocular cicatricial pemphigoid

PURPOSE: The presence of tumour necrosis factor-alpha (TNF-alpha) in conjunctivae affected by ocular cicatricial pemphigoid (OCP) was investigated. METHODS: Biopsy specimens from the conjunctivae of eight patients with OCP, three patients with atopic keratoconjunctivitis (AKC) and two normal subjects were studied for the expression of TNF-alpha by immunohistochemistry. Two independent, masked investigators evaluated the specimens. All samples were similarly processed by a third investigator. RESULTS: No TNF-alpha was discerned in the normal conjunctival sections; small amounts of TNF-alpha were observed in the atopic keratoconjunctivitis specimens. TNF-alpha was present in substantial amounts in conjunctival sections of patients with OCP. The expression of TNF-alpha was detected in both epithelial and stromal cells of conjunctivae from OCP patients. CONCLUSIONS: The presence of TNF-alpha in conjunctivae affected by OCP may indicate that this cytokine plays an important role in the production and maintenance of conjuctival inflammation response and subsequent conjunctival scarring in patients with OCP. Further studies clarifying this potential role are warranted.     

Corneal epithelial cells and human conjunctival cell line (Chang) produce an interleukin 3-like factor

Tissue mast cells play a central role in the pathogenesis of allergic eye diseases. In the study reported here the authors investigated whether human corneal epithelial cells and a human epitheloid conjunctival cell line (Chang) can produce an interleukin 3 (IL 3)-like mast cell-activating factor. The activity was detected at a m.w. of 15 and 30 kD, the isoelectric points were located at a pH of 7.85, 7.15 and 6.75. The authors believe that this cytokine, which is produced by epithelial cells of the cornea and conjunctiva, might play an important role in the pathogenesis of allergic ocular diseases.     

Eosinophil granule proteins expressed in ocular cicatricial pemphigoid

BACKGROUND—Blister formation and tissue damage in bullous pemphigoid have been attributed to the release of eosinophil granule proteins—namely, to eosinophil derived cationic protein (ECP) and major basic protein (MBP). In the present investigation these eosinophil granule proteins were studied in the conjunctiva of patients with ocular cicatricial pemphigoid (OCP).
METHODS—Conjunctival biopsy specimens obtained from patients with subacute (n=8) or chronic conjunctival disease (n=13) were analysed histologically and immunohistochemically using antibodies directed against EG1 (stored and secreted ECP), EG2 (secreted ECP), MBP, CD45 (common leucocyte antigen), CD3 (pan T cell marker), and HLA-DR (class II antigen).
RESULTS—Subepithelial mononuclear cells, mast cells, and neutrophils were detected in all specimens. The number of mononuclear cells, neutrophils, CD45+ cells, CD3+ cells, and the HLA-DR expression were significantly higher in the subacute than in the chronic disease group. Some eosinophils were found in specimens from five of eight patients with subacute OCP, but in none of the patients with chronic disease. The eosinophil granule proteins (ECP and MBP) were found in the epithelium and substantia propria in patients with subacute conjunctivitis.
CONCLUSIONS—Subepithelial cell infiltration in the conjunctiva greatly differs between subacute and chronic ocular cicatricial pemphigoid specimens. The findings suggest that eosinophil granule proteins may participate in tissue damage in acute phase of inflammation in OCP.

     

The T cell receptor in normal and inflamed human conjunctiva.

The majority of human peripheral blood and lymphoid tissue T cells express the TCR alpha/beta heterodimer, while the TCR gamma/delta is expressed on only a small subset of T lymphocytes. However, the majority of murine intraepithelial lymphocytes and most Thy-1+ murine dendritic epidermal cells express the TCR gamma/delta. Selective homing of avian TCR gamma/delta bearing lymphocytes to the intestinal epithelium also has been shown. These findings have suggested that these cells play a role against transformation and infection. More recently, a role in autoimmunity also has been proposed. We examined normal human conjunctiva and inflamed conjunctiva from patients with ocular cicatricial pemphigoid (OCP), an autoimmune disorder, and atopic keratoconjunctivitis (AKC). The majority of T cells in the epithelium and substantia propria of normal conjunctiva expressed the TCR alpha/beta. Tropism of TCR gamma/delta-expressing lymphocytes to normal human conjunctiva was not present. However, in OCP, there was a statistically significant increase in the absolute number of TCR gamma/delta cells/mm2 (epithelium, 33.9 +/- 10.5 [mean +/- standard error of the mean] vs. 159.9 +/- 51.5, P = less than 0.0008; substantia propria, 4.1 +/- 0.9 vs. 240.1 +/- 191.3, P less than 0.002) and TCR gamma/delta cells as a percentage of CD3+ cells (epithelium, 0.18 +/- 0.06 vs. 0.39 +/- 0.07, P = less than 0.02; substantia propria, 0.10 +/- 0.05 vs 0.33 +/- 0.08, P = less than 0.03). This was not the case for AKC. These findings suggest that TCR gamma/delta lymphocytes play a specific but undefined role in certain conjunctival inflammatory conditions and may be important in autoimmunity.     

Human mast cell subtypes in conjunctiva of patients with atopic keratoconjunctivitis,ocular cicatricial pemphigoid and Stevens-Johnson syndrome

Purpose: Investigate mast cell (MC S ) subtypes in atopic keratoconjunctivitis (AKC), ocular cicatrical pemphigoid (OCP), and Stevens-Johnson Syndrome (SJS). Methods: MC S subtypes were determined by immunohistochemistry of conjunctiva (obtained from 34 patients – 9 AKC, 9 OCP, 9 SJS and 7 normal) using monoclonal antibodies directed against chymase (MC C ) and tryptase (MC T ). Double staining was used to distinguish MC S as positive for both chymase and tryptase (MC TC ). Results: The number of MC S was significantly increased in AKC, OCP and SJS patients, compared to normal subjects. MC C were especially high in AKC, and moderately high in OCP. MC T and MC TC were similar in each disease group. Conclusions: While the AKC findings were not surprising, the result in OCP and SJS suggests that MC S play an underappreciated role in the inflammatory process of these disorders. Disparate proportions of MC S subtypes in these diseases may imply differential functions of MC S in these disorders.     

Distribution and characterisation of rat choroidal mast cells.

Despite the implication that choroidal mast cells are involved in the onset of experimental autoimmune uveoretinitis (EAU), a widely used animal model of uveoretinitis, little is known of these cells. In the present study the distribution, total number, regional density, and phenotype of choroidal mast cells were examined in Lewis, Wistar Furth, PVG/c, and brown Norway rats. Choroidal mast cells were predominantly associated with arteries and arterioles of more than 30 microns diameter which lie in the outer (sclerad) choroid. The density of mast cells was greatest in the posterior choroid with density diminishing anteriorly. The choroid of male Lewis rats contained significantly greater number of mast cells than that of females (p < 0.01). Histochemical (Alcian blue/safranin) and immunohistochemical (anti-rat mast cell protease I and II monoclonal antibodies) studies revealed choroidal mast cells were of the connective tissue type. However, granule proteinase content appeared less than that of well characterised connective tissue mast cell populations such as those in mesentery and skin. Lewis rats exhibited the highest density of choroidal mast cells (23.6 (SD 1.2)/mm2), Wistar Furth approximately half that of Lewis (13.5 (0.7)/mm2) while PVG/c and brown Norway rats had very low densities (3.06(0.3); 1.95(0.2/mm2 respectively). These studies provide valuable choroidal mast cell data for rats which may have implications for our understanding of experimental models of intraocular inflammation and clinical uveitis.     

Role of chymase on growth of cultured canine Tenon's capsule fibroblasts and scarring in a canine conjunctival flap model

Chymase is a chymotrypsin-like serine protease contained in the secretory granules of mast cells. Recently, we reported that chymase activity and the number of chymase-positive mast cells in conjunctival tissues were significantly increased during the wound healing process in a hamster model of glaucoma surgery. However, it has been unclear the role of chymase on conjunctival scarring. In the present study, we evaluated the effect of dog chymase on cell proliferation of fibroblasts established from canine Tenon's capsule and the effect of a chymase inhibitor on scarring in a canine conjunctival flap model. After a fibroblast cell culture was established from canine Tenon's capsules, the fibroblasts were incubated in the presence of dog chymase (5-20 ng ml(-1)). Cell proliferation was evaluated by bromodeoxyuridine incorporation. In a canine conjunctival flap model, a sponge treated with a chymase inhibitor, Suc-Val-Pro-Phe(P)(OPh)(2), or placebo was placed in between the conjunctiva and sclera and the conjunctival incision was closed. One week after the surgery, adhesion degree was assessed, and chymase activities in the conjunctival lesion and in the areas of the conjunctiva and sclera were measured. In cultured canine Tenon's capsule fibroblasts, dog chymase significantly increased cell proliferation, and this chymase-dependent proliferation was completely suppressed by the chymase inhibitor. In the canine surgical model, chymase activity in placebo-treated eyes was significantly increased compared to control eyes, while it was significantly decreased by treatment with the chymase inhibitor. Scores for adhesion degree in the chymase inhibitor-treated eyes were significantly decreased in comparison with those in placebo-treated eyes. The conjunctival area in the chymase inhibitor-treated eyes was also suppressed to 52.6% compared with that in placebo-treated treated eyes. In conclusion, chymase stimulates proliferation of fibroblasts derived from canine Tenon's capsule and chymase may play an important role in scarring after glaucoma surgery.     

Collagen types I and III in giant papillae of vernal keratoconjunctivitis.

AIMS--The objective of this study was to investigate alterations in conjunctival collagen and proteoglycans in the conjunctival giant papillae of patients with vernal keratoconjunctivitis (VKC). METHODS--Tissue samples from tarsal giant papillae of seven eyes from five patients with VKC, and five tarsal conjunctival samples from five normal patients were obtained. Tissues were processed and stained with haematoxylin and eosin, Van Gieson, trichromic Mallory, toluidine blue, Alcian blue, and alkaline Giemsa. Collagen extraction was performed in acetic acid and pepsin, total collagen was quantified using hydroxy-proline levels, and collagen types I and III were analysed by gel electrophoresis (SDS-PAGE). Proteoglycans were quantified using uronic acid levels. RESULTS--Histological evaluation showed a significant increase of mast cells in the epithelium (0/mm2 v 147/mm2, p < 0.01) and in the stroma (5.1/mm2 v 80/mm2, p < 0.01) of VKC patients. Collagen fibres were thicker and arranged irregularly, with the total amount significantly increased. Owing to an increased percentage of type III collagen, the ratio of collagen types I to III was decreased. Proteoglycans were also reduced in VKC samples. CONCLUSION--The well known morphological abnormalities observed in VKC correspond to alterations in the ratio between collagens and proteoglycans, and between different types of collagen. The greatly increased number of mast cells found in these tissues suggests an active role for these cells in the abnormal connective tissue metabolism observed in VKC.