Conjunctival cell glycoprotein pattern of healthy persons and of patients with primary Sjögren's syndrome--light microscopical investigation using lectin probes

Rebamipide increases the mucin-like glycoprotein production in corneal epithelial cells

PURPOSE

Dry eye is a multifactorial disease of tears and the ocular surface due to tear deficiency or excessive tear evaporation. Tear film instability is due to a disturbance in ocular surface mucin leading to a dysfunction of mucin, resulting in dry eye. In this study, we examined the effect of rebamipide, an anti-ulcer agent, on glycoconjugate production, as an indicator of mucin-like glycoprotein in cultured corneal epithelial cells. Further, we investigated the effect of rebamipide on the gene expression of membrane-associated mucins.

METHODS

Confluent cultured human corneal epithelial cells were incubated with rebamipide for 24 h. The glycoconjugate content in the supernatant and the cell extracts was measured by wheat germ agglutinin-enzyme-linked lectin assay combined gel-filtration method. In the experiment on mucin gene expression, cultured human corneal epithelial cells were collected at 0, 3, 6, and 12 h after administration of rebamipide. Real-time quantitative polymerase chain reaction was used to analyze the quantity of MUC1, MUC 4, and MUC16 gene expression.

RESULTS

Rebamipide significantly increased the glycoconjugate contents in the supernatant and cell extract. In the mucin gene expression in the cells, rebamipide increased MUC1 and MUC4 gene expression, but did not increase MUC16 gene expression.

CONCLUSIONS

Rebamipide promoted glycoconjugate, which has a property as a mucin-like glycoprotein, in human corneal epithelial cells. The increased production was mediated by MUC1 and MUC4 gene expression.

Mucosal microvilli in dry eye patients with chronic GVHD

The ocular surface is a frequent target tissue of mucosal chronic GVHD (cGVHD). We investigated the histopathological features of the conjunctival microvilli in patients with cGVHD. Conjunctival tissue specimens from patients with cGVHD or Sjögren's syndrome (SS) or from healthy individuals were examined by light microscopy and EM, impression cytology, and immunohistochemistry. The cGVHD conjunctivae showed significantly more metaplasia and fewer goblet cells than the SS and normal conjunctivae. Abundant CD8(+) T cells infiltrated the basal epithelia in the cGVHD conjunctiva. The microvilli per standard epithelial unit and the secretory vesicles were counted by analyzing electron micrographs. The mean number of mucosal microvilli was significantly lower in the cGVHD than that in the SS or normal specimens, and the microvilli were significantly shorter, with a smaller height-width ratio. The mean number of secretory vesicles was also significantly lower, and the membrane-spanning mucin thinner, in the cGVHD compared with the SS and normal specimens. Thus, the conjunctival mucosal microvilli of cGVHD patients were significantly different in number and morphology from those of SS and normal subjects. These may be important factors affecting the stability of the tear-film layer and its contribution to cGVHD-related dry eye.

Evaluation of ocular surface glycocalyx using lectin-conjugated fluorescein

Purpose:

A glycocalyx plays important roles in the ocular surface epithelium, but there is no direct simple method to evaluate ocular surface glycocalyx. We tested a wheat germ agglutinin conjugate of fluorescein (F-WGA) as a marker to demonstrate ocular surface glycocalyx in vivo.

Methods:

After a 5% F-WGA solution was applied to the eyes of eight healthy volunteers, fluorescent intensities of the central cornea and bulbar conjunctiva were measured by fluorophotometry. A 10% fluorescein-conjugated dextran solution served as the control. Changes in fluorescent intensities of the ocular surface following a challenge with 5% N-acetyl cysteine, a conventional mucolytic agent, were tested in the second experiment. Saline instillation served as a control.

Results:

The ocular surface was diffusely stained by F-WGA. Breakup of the precorneal tear film was not apparent, possibly because F-WGA was bound to the glycocalyx of the ocular surface epithelium. F-WGA fluorescent intensities were high in the superior, nasal, and inferior regions of the bulbar conjunctiva and low in the temporal conjunctiva and cornea. No such regional differences were observed with fluorescein-conjugated dextran. F-WGA fluorescent intensities decreased significantly with N-acetyl cysteine instillation, whereas they were not affected by saline instillation.

Conclusion:

The fluorophotometric method may be used to evaluate the glycocalyx quantitatively in the ocular surface in vivo.

Interleukin-9 induces goblet cell hyperplasia during repair of human airway epithelia

Asthma is characterized by airway inflammation, smooth muscle hyperreactivity, and airway remodeling with excessive mucus production. The effect cytokines like interleukin (IL)-9 have on airway epithelia has been addressed using murine models of asthma, as well as transgenic and knockout mice. Though highly informative, differences exist between mouse and human airway epithelia, including cellular composition (e.g., Clara cells) and stem cell/plasticity capabilities. Therefore, to address cytokine effects on human airway epithelia, we have used a primary model system to ask whether IL-9 can alter cell fates of human airway epithelia. Here, we show that IL-9 has little effect on fully differentiated ciliated human airway epithelia. However, in the setting of airway injury repair, IL-9 results in goblet cell hyperplasia. A similar response was observed when the epithelium was exposed to IL-9 before it became fully differentiated. Moreover, exposure to IL-9 resulted in increased lysozyme and mucus production by the epithelia. Thus, a combination of IL-9 and mechanical injury can explain, in part, goblet cell hyperplasia that is evident in the lungs of individuals with asthma. These data suggest that interventions that limit airway epithelial damage, block IL-9, or modulate the repair process should result in decreased airway remodeling and prevent the chronic manifestations of this disease.

Jacalin: a jackfruit (Artocarpus heterophyllus) seed-derived lectin of versatile applications in immunobiological research

Jacalin, the major protein from the jackfruit (Artocarpus heterophyllus) seeds, is a tetrameric two-chain lectin (molecular mass 65 kDa) combining a heavy alpha chain of 133 amino acid residues with a light beta chain of 20-21 amino acid residues. It is highly specific for the alpha-O-glycoside of the disaccharide Thomsen-Friedenreich antigen (Gal beta1-3GalNAc), even in its sialylated form. This property has made jacalin suitable for studying various O-linked glycoproteins, particularly human IgA1. Jacalin's uniqueness in being strongly mitogenic for human CD4+ T lymphocytes has made it a useful tool for the evaluation of the immune status of patients infected with human immunodeficiency virus (HIV)-1. The abundance of source material for the production of jacalin, its ease of purification, yield and stability have made it an attractive cost-effective lectin. It has found applications in diverse areas such as the isolation of human plasma glycoproteins (IgA1, C1-inhibitor, hemopexin, alpha2-HSG), the investigation of IgA-nephropathy, the analysis of O-linked glycoproteins and the detection of tumours.

Sjögren's syndrome diagnosis: a comparison of conjunctival and gingival impressions and salivary gland biopsy

This study reviewed 43 patients with Sjögren's syndrome. All of the patients complained of either dry eye and/or dry mouth. Their clinical records were compared with results of three laboratory diagnostic tests to determine the most sensitive test. Out of 30 patients who complained of both dry eye and dry mouth, 10 had positive conjunctival impressions, 20 had positive gingival impressions and 24 had positive salivary gland biopsies. Of 5 patients who suffered from only dry mouth, 2 had positive conjunctival impressions, 3 had positive gingival impressions and 3 had positive salivary gland biopsies. Of 7 patients with only dry eye complaints, there were 3 positive conjunctival impressions, 5 positive gingival impressions, and 6 positive salivary gland biopsies. Out of 6 healthy controls without complaints of dry eyes/mouth, there were no positive conjunctival impressions, 4 positive gingival impressions, and 5 positive salivary gland biopsies. Gingival impression appears to be nearly as sensitive as salivary gland biopsy in this group of patients suffering from Sjögren's Syndrome.

The normal human tear glycoprotein profile detected with lectin probes

Tear samples were collected from 46 healthy volunteers evenly distributed according to sex and age (mean age 43.5 years). Samples were denatured in a Tris-HCl sample buffer containing 2-mercaptoethanol and SDS, and applied to a gradient SDS-polyacrylamide gel for electrophoresis. The proteinaceous material was transferred to nitrocellulose by a semi-dry blotting technique, and the glycoprotein content subsequently visualized by incubation with four lectins (WGA, PHA, PSA and SBA) and staining with avidin horseradish-peroxidase. Glycoprotein bands were generally found to be significantly less frequent in persons under the age of 30 years. Apart from this the technique gave a uniform picture of the glycoprotein profile, with only modest differences according to age and/or sex. The technique may therefore be suitable for the detection of differences in the glycoprotein composition indicative of disease.

Beneficial effect of sodium sucrose-sulfate on the ocular surface of patients with severe KCS in primary Sjögren's syndrome

Sucralfate (aluminium sucrose-sulfate), a well known gastric mucosal protectant, has been tested topically on 22 patients (20 females and 2 males) suffering from primary Sjögren's syndrome. Median treatment period was 6 months (range 1-19 months). Statistically significant improvement in the ocular surface condition was found judged from the reduction in Rose-Bengal score (P less than or equal to 0.00005). The beneficial effect appeared within the first 1-4 months of treatment. No adverse side effects were encountered.

Lectin-binding sites in the anterior segment of the human eye

The anterior segment of the human eye was screened for differences in the lectin-binding patterns of Con A, PNA, GS-I, WGA, SBA, DBA, and UEA-I to enable cell typing for cell-culture purposes. An immunohistochemical technique combining an indirect antibody-lectin method with the avidin-biotin system was used. Con A and WGA were bound by all cells except the conjunctival goblet cells. UEA-I was exclusively bound by both vascular endothelial cells and some corneal and conjunctival epithelial cells. The binding of GS-I, PNA, SBA, and DBA showed an uneven pattern and differed among the cases investigated. The reasons for these differences are not clear. Our results indicate that the usefulness of lectins for cell-typing purposes is restricted and must be determined for every case.