Rat lens epithelial cell damage and cataract formation induced by immunological response to bovine lens membrane protein

Purpose: To evaluate the correlation of cataractogenesis and immune mechanisms, we investigated the rat lens morphologically and immunologically.Methods and Results: Wistar rats were divided into three groups: Group A was immunized with bovine-lens membrane protein (B-LMP) and adjuvant, Group B was immunized with adjuvant only, and Group C was not given any treatment as a control. Titer levels of anti-B-LMP antibody and anti-rat-LMP antibody were elevated and posterior subcapsular cataract was developed in Group A. In flat preparations, a noncellular part in the lens epithelium was observed in all members of Group A. In this noncellular part, a lens capsule protruding into the lens epithelial cell layer was observed by light microscopy.Conclusion: These data suggest that lens epithelial cells may be damaged by immune response, causing the development of cataract.

Lens epithelium-derived growth factor: effects on growth and survival of lens epithelial cells, keratinocytes, and fibroblasts.

We isolated a clone encoding a protein from a human lens epithelial cell (LEC) cDNA library with antibody (Ab) from a cataract patient and named it "lens epithelium-derived growth factor" (LEDGF). LEDGF is found to be identical to p75, a coactivator of both transcription (1) and pre-mRNA splicing (2). In serum-free medium LEDGF stimulated growth of LECs, cos7 cells, skin fibroblasts, and keratinocytes, and prolonged cell survival. Without LEDGF, the aforementioned cells did not survive. Also in serum-free medium, Ab to LEDGF neutralizing LEDGF blocked cell growth and caused cell death. Thus, LEDGF, a regulatory factor, may play an important role for growth and survival of a wide range of cell types.

[Rat lens epithelial cell damage and cataract formation induced by immunological response to bovine lens membrane protein].

PURPOSE: To evaluate the correlation of cataractogenesis and immune mechanisms, we investigated the rat lens morphologically and immunologically. METHODS AND RESULTS: Wistar rats were divided into three groups: Group A was immunized with bovine-lens membrane protein (B-LMP) and adjuvant, Group B was immunized with adjuvant only, and Group C was not given any treatment as a control. Titer levels of anti-B-LMP antibody and anti-Rat-LMP antibody were elevated and posterior subcapsular cataract was developed in Group A. In flat preparations, a noncellular part in the lens epithelium was observed in all members of Group A. In this noncellular part, a lens capsule protruding into the lens epithelial cell layer was observed by light microscopy. CONCLUSION: These data suggest that lens epithelial cells may be damaged by immune response, causing the development of cataract.

Antibodies to a microbial peptide sharing sequence homology with betaA3-crystallin damage lens epithelial cells in vitro and in vivo.

Circulating auto-antibodies (Abs) against lens antigens (Ags) are highly prevalent in patients with cataract, but their origin and pathogenic significance are unknown. We hypothesized that Abs raised after exposure to infectious microbes could cross-react with lens Ags. To test this hypothesis, we generated a monoclonal Ab to human betaA3-crystallin. Epitope analysis indicated that the ETQAE sequence in the N-terminus region of betaA3-crystallin was critical for mounting a humoral response. Similar sequences were found in three microbial Ags. Mice injected with a microbial oligopeptide containing ETQAE emulsified with complete Freund's adjuvant (CFA) raised Abs which cross-reacted with betaA3-crystallin and developed lens epithelial cell (LEC) damage in vitro. We also genetically engineered an betaA3-crystallin-expressing E. coli. Mice immunized with the recombinant E. coli developed LEC damage. These results support the hypothesis that exposure to microbes having Ags homologous to self Ags can trigger a humoral immune response that leads to LEC damage in mice.

Oral administration of lens homogenate suppresses antibody production in mice injected with beta-crystallin emulsified in CFA.

Auto-antibodies (Abs) against lens antigens (Ags) are present in most patients with age-related cataract, and with complement they kill lens epithelial cells (LECs) in vitro. We studied, in an animal model, whether cytotoxic Abs against lens Ags can be suppressed by oral administration of the Ags. Mice were fed calf lens homogenate, 4 mg/mouse, every 4 days for 4-5 weeks, or bovine serum albumin (BSA) before and after immunisation with beta-crystallins emulsified in complete Freund's adjuvant (CFA). Sera from these animals were analysed for Abs to beta-crystallins by enzyme-linked immunosorbent assay (ELISA) and protein blot analysis. In addition, we studied the proliferative response of T-lymphocytes to beta-crystallins. The titer of anti-beta-crystallin Abs in the control animals fed BSA gradually increased to 1.5 x 10(-6) by the 5th week after the first injection. In contrast, the titer of anti-beta-crystallin Abs in animals fed calf lens homogenate was reduced to 30-70% of the control. Feeding lens homogenate prior to or concomitant with beta-crystallins immunization, was more effective than feeding after immunization (65% suppression vs. 30% suppression, respectively). Also the proliferative response of T-lymphocytes to beta-crystallins in mice fed homogenate was suppressed significantly. Thus, oral administration of lens homogenate is a specific and nontoxic method of suppressing anti-beta-crystallin Ab production in mice. We are exploring the therapeutic value of oral administration of lens proteins in age-related cataract.

Anti-beta-crystallin antibodies (mouse) or sera from humans with age-related cataract are cytotoxic for lens epithelial cells in culture.

Circulating autoantibodies against lens antigens are prevalent in patients with age-related cataract (ARC), but their pathogenic significance is unknown. We hypothesized that these autoantibodies are cytotoxic for lens epithelial cells (LECs). To test this hypothesis. We incubated LECs with mouse polyclonal or monoclonal antibodies against beta-crystallin (anti-beta) in the presence or absence of guinea pig complement. We found that anti-beta in the presence of the complement bound to and killed mouse LECs (MLECs) and human LECs (HLECs). Sera obtained from patients with ARC also were cytotoxic to both HLECs and MLECs in culture. Heat-inactivated human sera were not cytotoxic to LECs in the absence of the complement, but were cytotoxic to both HLECs and MLECs in the presence of additional complement. These results support the hypothesis that autoantibodies against lens antigens are cytotoxic to LECs, and that cell death may involve complement-mediated pathways.

Reduced glutathione levels in senile cataractous lens epithelial cells.

A sensitive assay, utilizing high performance liquid chromatography and sulfhydryl (SH) fluorescence labeling, was used for the quantitative determination of reduced glutathione (GSH) and cysteine (CySH) in senile cataractous lens epithelial cells. The capsule-epithelia (CE), obtained following cataract surgery, were soaked in 0.3 ml saline at room temperature for 1 hour. Detached epithelial cells and the capsule with attached residual cells were assayed for GSH and CySH. Regression analysis of the relation between epithelial protein content and capsule wet weight was performed to evaluate the amount of contamination of the CE samples with lens cortex. GSH levels in the cataractous lens epithelial cells were 23.0 +/- 11.2 (Mean +/- S.D.) nmol/mg protein (n = 15); CySH levels were 0.51 +/- 0.50 nmol/mg protein (n = 12). No differences in GSH levels were observed between immature and mature cataracts. Thus, GSH levels in the lens epithelial cells did not appear to decrease with the progression of the senile cataracts.