Development of monoclonal antibodies to rabbit ocular mucin

Monoclonal antibodies against rabbit ocular mucin (ROM) and porcine stomach mucin (PSM) were developed to explore the biosynthesis and functional significance of ocular mucin. A nitrocellulose-based dot enzyme-linked immunosorbent assay (ELISA) was developed for hybridoma screening and mucin quantitation. The sensitivity was found to be at the level of 1 ng mucin per dot, which was about 1000 times more sensitive than that of our previously-reported histochemical method. Both anti-ROM and anti-PSM antibodies demonstrated specific bindings to rabbit conjunctival goblet cells and apical surface mucin of conjunctival epithelium by immunofluorescent and peroxidase-anti-peroxidase studies. These antibodies also showed specific bindings to ocular mucin and goblet cells of human conjunctiva on the impression cytology specimens obtained from normal subjects. These results indicate that these mucin-specific monoclonal antibodies can be used as a marker for goblet cell differentiation and as a probe to measure mucin content in the tear film and ocular surface. Selective loss of goblet cells and mucin deficiency were noted in impression cytology specimens of patients with various mucin-deficient disorders. This information indicates the potential application of these antibodies to study various ocular surface disorders characterized by alterations in goblet cell differentiation and mucin biosynthesis.     

Development of a rabbit model of tear film instability and evaluation of viscosity of artificial tear preparations

OBJECTIVE: The purposes of this study were to establish a quantitative method for evaluating rabbit tear film status and investigate the efficacy of artificial tear preparations through ocular surface bathing or eye drop application. METHODS: The rabbit tear film was evaluated using a noninvasive specular reflection video recording system. The appearance of a tear break area (TBA) on the tear film images (7.4 mm2/mm) after 30 seconds of eye opening was quantified by image analysis. To induce disruption of the rabbit tear film, the ocular surface was challenged for 60 minutes with 1 ppm hypochloric acid (HOCl). Immediately after irrigation, artificial tear preparations composed of viscosity agents sodium hyaluronate (SH), hydroxypropylmethycellulose (HPMC), hydroxyethylcellulose (HEC), or chondroitin sulfate (CS) were applied to the rabbit eye through ocular surface bathing or eye drop application, and the recovery of the disrupted tear film was compared for each preparation. RESULTS: A dramatic increase in TBA was observed immediately after the ocular surface was challenged with HOCl, and it returned to the initial level after 6 hours. Immediately after ocular surface bathing and eye drop application, a dramatic recovery of TBA was observed in all the test solution-treated eyes. One hour after treatments, prolonged amelioration of the tear film instability was observed after ocular surface bathing, but not by eye drop application, with the artificial tear preparations composed of HPMC or SH. CONCLUSION: Ocular surface bathing with artificial tear preparations composed of a suitable viscosity agents could be useful in managing tear film instability.     

Ocular hypotensive efficacy of topical epinephrine in normotensive and hypertensive rabbits: continuous drug delivery vs eyedrops.

The ocular hypotensive efficacy of continuously delivered epinephrine is compared to that of pulsed doses provided by eyedrops in both normotensive and hypertensive rabbit eyes. In normotensive eyes, 2 microgram/hr and 4 microgram/hr epinephrine delivered into the tear film continuously for 12 hours reduces intraocular pressure as well as eyedrop pulses of 0.5% epinephrine hydrochloride or 2% epinephrine bitartrate (doses of 500 and 1100 microgram, respectively). Ocular hypertension induced by an intragastric water load in rabbits is significantly inhibited by continuous delivery of epinephrine at the rates of 3 or 6 microgram/hr, or by 2% epinephrine bitartrate (1% free base) eyedrops. Epinephrine delivered continuously at rates of 2-6 microgram/hr for 6 to 12 hours (12-72 microgram total) has hypotensive efficacy equivalent to 15 to 40 times as much epinephrine applied once in eyedrops. Epinephrine bitartrate eyedrops reduce tear film pH well below normal. Continuous delivery of epinephrine bitartrate does not reduce tear film pH below normal levels.     

超声乳化白内障摘除联合小梁切除术对眼表的影响

目的：采用Keratograph 5M眼表综合分析仪比较小梁切除术和超声乳化白内障摘除联合小梁切除术对眼表的影响。

方法：纳入原发性闭角型青光眼合并白内障患者62例62眼,按手术方式分为两组：小梁切除术组32例32眼,超声乳化白内障摘除联合小梁切除术组(青白联合手术组)30例30眼。运用Keratograph 5M评估术前,术后3d,1、 3mo的非侵入性首次泪膜破裂时间(NifBUT)、非侵入性平均泪膜破裂时间(NiaBUT)、泪河高度(TMH)和角膜荧光素染色评分(CFS)。

结果：术前两组患者眼表参数比较差异均无统计学意义(P>0.05)。术后3d青白联合手术组的NiaBUT、NifBUT、CFS、TMH最差,分别为10.13±1.48、12.59±1.96s、0.80±0.22分与0.31±0.02mm,变化幅度明显高于小梁切除组(均 P<0.05),术后1mo两组的各项指标均有所恢复,但直到术后3mo仍未完全恢复到术前水平。

结论：眼表综合分析仪可以客观、精确地用于评估抗青光眼手术后泪膜功能的变化。在术后3mo短期内超声乳化白内障摘除联合小梁切除术比单纯小梁切除术对眼表的影响更为严重,提示在此期间应加强对眼表的护理。     

Stimulation of tear secretion by topical agents that increase cyclic nucleotide levels

The authors examined the effect of topical application of agents known to increase cyclic nucleotide levels on tear secretion by accessory lacrimal gland tissue in their rabbit model for keratoconjunctivitis sicca (KCS). Tear secretion was studied by changes in tear film osmolarity and tear volume caused by application of the agents relative to application of isotonic buffer solution alone. A decrease in tear film osmolarity or increase in tear volume was interpreted as an increase in tear secretion. Irritative stimulation was distinguished from pharmacologic stimulation by the prior use of topical proparacaine. The following agents significantly decreased tear film osmolarity and increased tear volume: vasoactive intestinal peptide (2 X 10(-8) to 2 X 10(-6) M); three pro-opiomelanocortin fragments alpha-, beta-, and gamma-melanocyte stimulating hormone at 10(-4), 10(-3), and 10(-3) M, respectively; the permeable cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) analogs 8-Br cAMP (0.3-3.0 X 10(-3) M) and 8-Br cGMP (1.0-10.0 X 10(-3) M); and the cyclic nucleotide phosphodiesterase inhibitor 1-isobutyl-3-methyl xanthine (0.3-3.0 X 10(-3) M). Forskolin (2 X 10(-4) M), which activates the catalytic subunits of adenyl cyclase, increased tear volume significantly. Secretin, adrenocorticotropic hormone, and pilocarpine were ineffective. The authors conclude that agents that increase either cAMP or cGMP levels pharmacologically stimulated tear secretion when applied topically to rabbit eyes with surgically induced KCS.     

Intercellular relationships in the synthesis of macromolecules by organ cultures of corneas

Sepharose CL-4B chromatography of guanidine hydrochloride and aqueous extracts of 3H-glucosamine labeled intact corneal tissue reveals four peaks representing proteoglycans and glycoproteins. To evaluate the universality of the 4th peak, hereafter designated as Sepharose CL-4B (IV), its presence was investigated in rabbit, bovine, cat, rhesus monkey, and human corneal preparations. Following incubation in isotopically labeled medium, corneas were extracted with aqueous and/or 4M guanidine hydrochloride and subjected to Sepharose CL-4B chromatography. Sepharose CL-4B (IV) was detected in all species studied; 3H-glucosamine and 14C-amino acids, but not 35SO4, were incorporated into this peak which eluted in the range consistent with an apparent molecular weight of approximately 30,000 D. To determine which layers were involved in the synthesis of Sepharose CL-4B (IV) the layers of the rabbit cornea were incubated separately (stroma scraped of endothelium and/or epithelium, epithelium only, endothelium only). A distinct Sepharose CL-4B (IV) peak was not identified in the chromatographs obtained from organ cultures of corneal epithelium, endothelium, or from corneal stroma scraped of epithelium and/or endothelium. This decrease in Sepharose CL-4B (IV) synthesis occurred even if the scraped cornea was not allowed to expand in volume by compressing it beneath a membrane porous to the incubation medium. Thus, Sepharose CL-4B (IV) synthesis was enhanced significantly by the stroma being in conjunction with other corneal cells as they exist in vivo.     

Human preocular mucins reflect changes in surface physiology

BACKGROUND/AIMS: Mucin function is associated with both peptide core and glycosylation characteristics. The authors assessed whether structural alterations occurring during mucin residence in the tear film reflect changes in ocular surface physiology. METHODS: Ocular surface mucus was collected from normal volunteers as N-acetyl cysteine (NAcCys) washes or directly from the speculum after cataract surgery. To assess the influence of surface health on mucins, NAcCys washings were also obtained from patients with symptoms, but no clinical signs of dry eye (symptomatics). Mucins were extracted in guanidine hydrochloride (GuHCl) with protease inhibitors. Buoyant density of mucin species, a correlate of glycosylation density, was followed by reactivity with anti-peptide core antibodies. Mucin hydrodynamic volume was assessed by gel filtration on Sepharose CL2B. RESULTS: Surface fluid and mucus contained soluble forms of MUC1, MUC2, MUC4, and MUC5AC and also the same species requiring DTT solubilisation. Reactivity with antibodies to MUC2 and MUC5AC peaked at 1.3-1.5 g/ml in normals, while dominated by underglycosylated forms in symptomatics. Surface mucins were predominantly smaller than intracellular species. MUC2 size distributions were different in symptomatics and normals, while those of MUC5AC were similar in these two groups. CONCLUSIONS: A reduction in surface mucin size indicates post-secretory cleavage. Dissimilarities in surface mucin glycosylation and individual MUC size distributions in symptomatics suggest changes in preocular mucin that might precede dry eye signs.     

INS365 suppresses loss of corneal epithelial integrity by secretion of mucin-like glycoprotein in a rabbit short-term dry eye model.

P2Y2 receptor agonists, like UTP and ATP, stimulate mucin secretion from goblet cells in vitro. Therefore, mucin stimulants could be good candidates for the treatment of dry eye syndrome because mucin increases the tear film stability and protects against desiccation of ocular surface. INS365 is a more stable P2Y2 receptor agonist than UTP. In the present study, we evaluated, in normal rabbit eyes, its effectiveness to release mucin from goblet cells and to protect the corneal damage induced by desiccation. For mucin secretion, impression cytology was performed following the instillation of INS365 solution or saline into the conjunctival sac. The specimens were stained with periodic acid and Schiff (PAS) reagent, and then the staining area was calculated using computer software. INS365 dose-dependently decreased the PAS staining area of conjunctival goblet cells from 2 to 15 min post-application. Furthermore, we utilized the rabbit short-term dry eye model to evaluate if INS365 eyedrops could protect against any of the damage produced by blockage of blinking with ocular speculum. INS365 significantly suppressed corneal damage at concentrations of more than 0.1% w/v. These results suggest that this P2Y2 agonist is a good candidate for the treatment of dry eye disease.     

Observations of tear film break up on model eyes.

Models of the human eye's anterior surface were constructed from polymethylmethacrylate. Some models had a rigid gas permeable contact lens cemented to the corneal apex; others had strips of plastic or metal cemented at the location of the lids in the open human eye. When the level of water was lowered in the bath surrounding the upward-gazing eye model, tear film break up could be observed. Covering the model with mucin (from saliva) changed the pattern of tear film break up. On the mucin-covered model eye, the tear film break up resembled break up observed in the human eye. These studies on model eyes suggest that tear film break up occurs when tension in the tear film becomes greater than the tensile strength of the film. The mucin layer reduces the thickness of the tear film at break up and the thickness of the retreating film.     

Tear film instability induced by rigid contact lenses.

PURPOSE: To evaluate rigid contact lens-associated epithelial damage, the relationship between the tear film and the ocular surface epithelium was evaluated at the perilimbal area around rigid contact lenses (RCLs). METHODS: Twenty RCL [six polymethylmethacrylate (PMMA) and 14 rigid gas-permeable lens (RGPL)] wearers and 20 non-CL wearers were enrolled in this study. By using a newly developed tear interferometer, the noninvasive tear film break-up time (NIBUT) on the conjunctiva at the 3- and 9-o'clock portions was measured, and its stability evaluated. Fluorescein and sulforhodamine B staining was used to observe ocular-surface epithelial damage, and rose bengal staining was used to evaluate the mucin layer distribution. RESULTS: The conjunctival NIBUT at the 3- or 9-o'clock portions or both was abnormally shortened in 15 (75%) of 20 RCL-wearer eyes. Conjunctival epithelial staining at the 3- or 9-o'clock portion was seen in six (30%) of 20 eyes by using sulforhodamine B, and in four (20%) of 20 eyes by rose bengal; all of these eyes also demonstrated an abnormal tear film breakup. Corneal epithelial damage was seen in two (10%) of 20 RCL-wearer eyes at the 3- or 9-o'clock portions or both, and in both of these cases, conjunctival epithelial damage also was noted. Neither tear-film instability nor epithelial staining was seen in the normal controls. CONCLUSIONS: This study indicates that RCL-induced tear-film instability is associated with damage to the ocular-surface epithelium and mucin layer.     

The surface activity of purified ocular mucin at the air-liquid interface and interactions with meibomian lipids

PURPOSE: Ocular mucins are thought to contribute to the stability of the tear film by reducing surface tension. The purpose of this study was to compare the effect of different mucins and hyaluronic acid (HA) alone and mixed with meibomian lipids on the surface pressure at an air-liquid interface. METHODS: A Langmuir trough and Wilhelmy balance were used to measure and compare the surface activity of bovine submaxillary gland mucin (BSM), purified BSM, purified bovine ocular mucin and HA, and mixtures of these with meibomian lipids, phosphatidylcholine, and phosphatidylglycerol. Their appearance at the surface of an air-buffer interface was examined using epifluorescence microscopy. RESULTS: Purified ocular mucin had no surface activity even at concentrations that were 100 times more than normally occur in tears. By contrast, commercial BSM caused changes to surface pressure that were concentration dependent. The surface pressure-area profiles showed surface activity with maximum surface pressures of 12.3-22.5 mN/m depending on the concentration. Purified BSM showed no surface activity at low concentrations, whereas higher concentrations reached a maximum surface pressure of 25 mN/m. HA showed no surface activity, at low or high concentrations. Epifluorescence showed that the mucins were located at the air-buffer interface and changed the appearance of lipid films. CONCLUSION: Purified bovine ocular mucin and HA have no surface activity. However, despite having no surface activity in their own right, ocular mucins are likely to be present at the surface of the tear film, where they cause an increase in surface pressure by causing a compression of the lipids (a reorganization of the lipids) and alter the viscoelastic properties at the surface.     

应用角膜地形图仪观察老年干眼患者最早泪膜破裂位置

目的:观察老年干眼患者最早泪膜破裂位置的特征。方法:横断面研究。选取2019-07/12在我院诊治的老年干眼患者154例267眼,143眼为右眼,124眼为左眼。其中男71例,女83例,年龄68~90(平均73.40±4.13)岁。应用角膜地形图仪对患者进行最早发生泪膜破裂位置的测量,破裂位置以仪器观察的角膜方位按逆时针顺序分为4个区域,分别对应右眼的鼻上、颞上、颞下、鼻下4个区域和左眼的颞上、鼻上、鼻下、颞下4个区域。记录哪个区域泪膜最先出现破裂,同时记录最早破裂位置距角膜中心的距离。结果:右眼出现泪膜首先破裂最多的区域为鼻下(28.7%),然后是颞下(27.3%)、鼻上(20.3%)、颞上(11.2%),同时出现2~3个区域泪膜破裂占12.6%。左眼出现泪膜首先破裂最多的区域也为鼻下(31.5%),然后是颞下(25.0%)、鼻上(23.4%)、颞上(11.3%),同时出现2~3个区域泪膜破裂占8.9%。双眼之间泪膜破裂区域构成比的比较无差异(χ2=1.443,P=0.837)。双眼鼻下方泪膜破裂位置距角膜中心距离均以>1.5~2mm和>2~2.5mm为主。结论:老年干眼患者泪膜的破裂位置有一定的规律,双眼泪膜首次破裂均以角膜鼻下方为主,双眼没有显著性差异。     

Changes in ocular aberrations after instillation of artificial tears in dry-eye patients

PURPOSE: To study the effect of artificial tear instillation on ocular aberrations in dry-eye patients. SETTING: Research, Development and Innovation Department, Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: Ocular aberrations (total, spherical-like, and coma-like) were measured with a Hartmann-Shack aberrometer before and after artificial tear instillation (immediately and 10 minutes later) in 15 eyes of 15 dry-eye patients. RESULTS: Optical aberrations showed a statistically significant reduction after artificial tear instillation (P<.01). Total aberrations decreased on average by a factor of 2 to 3 times immediately after instillation; the reduction was maintained after 10 minutes (P>.01). CONCLUSIONS: After artificial tear instillation, the reduction in optical aberrations associated with an increasingly irregular tear film may cause an improvement in the optical quality of dry eyes. Wavefront analysis facilitates the evaluation of improvement in optical quality after artificial tear instillation in patients with dry eye.     

Ocular surface and MUC5AC alterations in atopic patients with corneal shield ulcers

PURPOSE: To describe MUC5AC alterations and the ocular surface disorder in atopic patients with or without corneal ulcers. METHODS: Atopic patients' eyes were divided into two groups according to the presence and absence of corneal ulceration. The subjects underwent corneal sensitivity measurements, Schirmer test, tear film break-up time (BUT), fluorescein and Rose Bengal staining of the ocular surface and conjunctival impression cytology and brush cytology. Impression cytology samples underwent PAS and immunohistochemical staining for MUC5AC. Brush cytology specimens underwent evaluation for inflammatory cell expression and quantitative real-time PCR for MUC5AC mRNA expression. The differences related to the tear function and ocular surface examination parameters between patients with and without corneal ulceration and healthy control subjects were studied. In addition, the differences of the study parameters related to ocular surface epithelial health and inflammatory status between patient eyes with atopic keratoconjunctivitis (AKC) and vernal keratoconjunctivitis (VKC) were investigated. RESULTS: The mean corneal sensitivity and BUT values were significantly lower in atopic patients with corneal ulcers, compared to patients without ulcers and controls (p < 0.001). Brush cytology specimens from patients with corneal ulcers revealed significantly higher expression of inflammatory cells compared to patients without ulcers and controls (p < 0.001). Impression cytology samples from eyes with corneal ulcers showed significant squamous metaplasia and reduction in goblet cell density compared to eyes without ulcers and eyes of control subjects. The mean squamous metaplasia grade was significantly higher in eyes with AKC compared to eyes with VKC (p < 0.02). The mean goblet cell density was significantly lower in eyes with AKC compared to eyes with VKC (p < 0.01). Specimens from eyes with corneal ulcers showed PAS positive mucin pickup and did not stain positive for MUC5AC. MUC5AC mRNA expression was significantly lower in eyes with corneal ulcers compared to eyes without ulcers and eyes of control subjects. MUC5AC mRNA expression was also significantly lower in eyes with AKC compared to eyes with VKC. CONCLUSIONS: Ocular surface inflammation, tear film instability, and decreased conjunctival MUC5AC mRNA expression were thought to be important in the pathogenesis of noninfectious corneal shield ulcers in atopic ocular surface disease.     

Study of mucin layer of tear film in patients with pterygium

PURPOSE: The aim of this study was to investigate the tears film, particularly mucin layer in patients with pterygium. MATERIAL AND METHODS: We examined 31 patients with pterygium--14 women and 17 men. Pterygium in one eye was found in 19 patients, in both eyes in 12. The control group consisted of 43 persons--21 women and 22 men. In our study were evaluated: marginal tears film, tears film break-up time (BUT), Schirmer's test and mucus fern patterns. RESULTS: The results showed no statistically significant difference in Schirmer's test in both groups. Marginal tears film was incorrect in 65.12% of the eyes with pterygium and in 34.89% eyes of the control group. Tears film break-up time was reduced statistically significant, in patients with pterygium. Abnormal mucus fern patterns (type III and IV) was observed in 38.95% of the eyes with pterygium and in 13.94% of the eyes in the control group. CONCLUSIONS: Disturbances of the tear film stability were found in the eyes with pterygium. The results of BUT and mucus fern patterns showed, that abnormalities of mucin layer to be responsible for these changes. Perhaps these observations will contribute to prevention of pterygium.     

Increased corneal permeability induced by the dual effects of transient tear film acidification and exposure to benzalkonium chloride

A number of common eyedrop solutions were found to be at acid pH and to have considerable acidic buffering capacity. Rabbit tears were shown to have weak buffering capacity at physiologic pH; a single drop of acidic ophthalmic preparation markedly reduced tear film pH for 10 to 15 min. One drop of pH 4 buffer eyedrop without other components reduced rabbit tear film pH in vivo by the same magnitude as the ophthalmic formulations; depressed pH persisted for at least 5 min. To assess the integrity of the corneal epithelial barrier after exposure to transiently acidified tear film, trace amounts of [¹⁴C]inulin were added to buffer solutions and the inulin concentrations in cornea and aqueous humor determined as ¹⁴C (d/min)/mg. Even 15 min after a pH 4 buffer eyedrop, mean corneal inulin concentration was three times that in pH 7 buffer-treated eyes. A concomitant increase in aqueous humor inulin concentration was observed. Corneal permeability was also assayed with the [¹⁴C]inulin instilled 15 min after application of a buffered eyedrop containing either 0·01 or 0·02% benzalkonium chloride, a common eyedrop preservative. In neutral pH solution, 0·01% benzalkonium chloride did not alter corneal permeability significantly, but the 0·02% solution increased corneal inulin concentration by a factor of seven compared to controls. In pH 4 buffer, however, both the 0·01% and 0·02% benzalkonium chloride solutions increased corneal inulin penetration—by tenfold and eighteenfold, respectively. Thus, the combined effects of acid buffering and benzalkonium chloride on corneal permeability were more than double the effects of either one alone.     

Rheumatoid arthritis is a risk factor for dry eye in the Indian population

PURPOSE: To compare the prevalence and severity of dry eye in patients with rheumatoid arthritis (RA) with that in age- and sex-matched controls in the Indian population. METHODS: A cross-sectional study was performed on 84 randomly selected eyes of 84 adult patients with well-documented rheumatoid arthritis and 84 eyes of 84 age- and sex-matched controls in the Department of Ophthalmology, Seth G.S. Medical College and K.E.M. Hospital. McMonnie's dry eye questionnaire was used to classify the patients on the basis of their symptoms. Dry eye was diagnosed if the wetting on Schirmer filter paper test was < or =5 mm at 5 minutes and the tear film breakup time was < 10 seconds on slit-lamp examination after fluorescein staining. RESULTS: Twenty three patients (27.3%) with rheumatoid arthritis had dry eyes based on the Schirmer test as compared to 10 (12%) age- and sex-matched controls; 19 (22.62%) patients with RA had a tear film breakup time of < 10 sec. on slit-lamp examination, compared to 8 (9.52%) patients without RA. The difference in the mean wetting (p = 0.003) and mean tear film breakup time (p < 0.001) between RA and non-RA patients was statistically significant. Ocular symptoms had a limited correlation with the results of these tests. CONCLUSIONS: Patients with RA in the Indian population have a significantly higher prevalence and severity of dry eye when compared to age- and sex-matched controls.     

Increased Tear Film Osmolarity in Systemic Lupus Erythematosus

Purpose: To evaluate tear film osmolarity in patients with systemic lupus erythematosus (SLE). Methods: A total of 55 eyes from 55 patients with SLE and 47 eyes from 47 age- and gender-matched healthy individuals were included in this study. Tear film osmolarity was evaluated with a lab-on-a-chip technique (TearLab; TearLab Corporation, San Diego, CA) in SLE patients in comparison with healthy individuals, and results were correlated to clinically available diagnostic tests for dry eye, such as tear ?lm break-up time (BUT), Schirmer’s test, and Ocular Surface Disease Index (OSDI). Results: The mean tear film osmolarity in the SLE patients and healthy individuals was 306.02 ± 13.27 mOsm/L and 300.74 ± 9.11 mOsm/L, respectively, which made for a statistically significant difference (p = 0.020). In the SLE group, tear film osmolarity was negatively correlated with the Schirmer’s test score and the BUT value (r = ?0.295 p = 0.029 and r = 0.347 p = 0.009, respectively), whereas tear film osmolarity was not correlated with OSDI score (r = ?0.182 p = 0.183). Conclusions: This study revealed that tear film hyperosmolarity and abnormal tear film function are associated with SLE.     

Characterization of human ocular mucin secretion mediated by 15(S)-HETE

PURPOSE: The eicosanoid 15-(S)-hydroxy-5,8,11,13-eicosatetraenoic acid [15(S)-HETE] is reported to stimulate mucin production in both airway and ocular surface epithelia. The current study was undertaken to evaluate the effects of 15(S)-HETE on secretion of specific ocular mucins by human conjunctiva. METHODS: Segments of human bulbar conjunctival tissue were incubated with 15(S)-HETE (1-1000 nM) for 30 minutes at 37 degrees C. Secretion of human ocular mucins MUC1, MUC2, MUC4, and MUC5AC into the incubation media was measured by dot-blot immunoassay using antibodies directed to unique mucin polypeptide epitopes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting were used to verify the specificity of anti-mucin antibody binding and to investigate the presence of MUC1 mucin in human tears. RESULTS: 15(S)-HETE (10(-8)-10(-6) M) stimulated secretion of conjunctival mucins in a concentration-dependent manner. Significant increases in total mucin secretion were observed at 10(-7) M 15(S)-HETE with a maximum response (>50% increase above controls) at 10(-6) M. Results of immunoassays showed that 15(S)-HETE differentially stimulates secretion of MUC1 mucin with no detectable effects on MUC2, MUC4, or MUC5AC release. Western analysis of tear samples from human volunteers indicated that MUC1 is a component of the preocular tear film. CONCLUSIONS: The results demonstrate that 15(S)-HETE is a selective secretogogue for MUC1 in isolated human conjunctival tissue. Although the biochemical mechanism(s) and cellular origins of MUC1 secretion remain to be established, the ubiquitous expression of MUC1 in corneal and conjunctival epithelia and its presence in human tears suggest that secreted MUC1 may contribute to the mucin layer that coats and protects the ocular surface.