Hyaluronan and chondroitin sulfate in rabbit tears

Therapie des Trockenen Auges

Die Therapie des Trockenen Auges stellt eine schwierige Aufgabe für den behandelnden Augenarzt dar. Fortschritte in unserem Verständnis der Risikofaktoren, der Ätiologie und Pathophysiologie des Trockenen Auges haben zu einer Weiterentwicklung der Behandlungsstrategien geführt. Vor Beginn der Therapie ist die korrekte Zuordnung in eine wässrig-muzinöse Tränenfilmdysfunktion (Mindersekretion), in eine lipidbedingte Tränenfilmdysfunktion (hyperevaporative Form durch eine abnormen Meibom-Drüsen-Physiologie) oder in eine variable Kombination wichtig. Unter Berücksichtigung aktueller Empfehlungen der DOG, des BVA und des TFOS DEWS II Unterausschusses wurde ein Behandlungsalgorithmus abgeleitet, der ein schrittweises Vorgehen je nach Schweregrad der Erkrankung darstellt.

Hyaluronan as a promising excipient for ocular drug delivery

Hyaluronan (HA) is a naturally occurring polysaccharide and well known for its exceptional properties such as high biocompatibility and biodegradability, along with a low immunogenicity. Besides its use for various biomedical applications it recently came into focus as a favorable excipient for the formulation of various ocular therapeutics. This review article summarizes the ocular distribution of HA and its most heavily investigated binding protein "cluster of differentiation 44" (CD44) which is the rationale for the clinical use of HA, primarily as an additive in ocular applications ranging from eye drops to contact lenses. Moreover, examples will be given for using HA in various pre-clinical approaches to generate entirely new therapeutics, most notably in the field of nanotechnology.

Altered hyaluronic acid content in tear fluid of patients with adenoviral conjunctivitis

The adenoviral conjunctivitis is one of the biggest causes of conjunctival infection in the world. Conjunctivitis causes relatively nonspecific symptoms, as hyperaemia and chemosis. Even after biomicroscopy, complex laboratory tests, such as viral culture, are necessary to identify the pathogen or its etiology. To contribute to the better understanding of the pathobiology of the adenoviral conjunctivitis, the tear fluids of patients with unilateral acute adenovirus conjunctivitis (UAAC), normal donors (control) and patients with allergic conjunctivitis were analyzed. Tear samples were collected with Schirmer strips from control, allergic conjunctivitis and UAAC patients, diagnosed by clinical signs. UAAC tears were tested positive in viral cultures. After the elution, HA was quantified using an ELISA-like fluorometric assay and the protein profile was determined by SDS-PAGE. A profound increase in the HA tear content in UAAC patients was found when compared to control and ALC. This HA increase in UAAC tears remarkably was not observed in tears from contralateral eyes without clinical signs, nor in allergic conjunctivitis. In addition a distinct profile of UAAC tear proteins was observed in patients with UAAC. The quantification of HA in the tear fluid is a rapid, sensitive and specific test. This molecule might be a biomarker candidate for acute conjunctivitis.

Novel porous matrix of hyaluronic acid for the three-dimensional culture of chondrocytes

A novel three-dimensional (3D) scaffold of chemically unmodified hyaluronic acid (HA) with minimum cross-linkage was developed for the culture of chondrocytes, thereby to promote cartilage repair. The porous structure of the scaffold was observed by scanning electron microscopy (SEM), and the pore size was controlled by fabrication conditions including swelling time and composition of the HA matrix. Rabbit primary chondrocytes and human chondrocytic cell lines (C-20/A4) were cultured in the HA matrix to investigate whether they can be applied to construct the cartilage tissue in vitro. The chondrocytes retained chondrocytic spherical morphology in this HA matrix. Moreover, results from the MTT assay showed good cellular viability within the HA matrix; optical density increased for up to 28 days, demonstrating that the cells continued to proliferate inside the HA matrix. Phenotypic analysis (RT-PCR, Alcian blue staining and quantification of s-GAG) showed that chondrocytes, when three-dimensionally cultured within the HA matrix, expressed transcripts encoding collagen type II and aggrecan, and produced sulfated glycosaminoglycans (s-GAG), indicating chondrogenic differentiation. The new HA matrix therefore appears as a potentially promising scaffold for the three-dimensional culture of chondrocytes for cartilage tissue engineering.

Quantitative analysis of chondroitin sulfate in tear fluids following laser in situ keratomileusis

PURPOSE

To report chondroitin sulfate (CS) concentrations in tear fluid following laser in situ keratomileusis (LASIK).

METHODS

Fourteen eyes that underwent LASIK were enrolled. We measured the CS isomers chondroitin 4 sulfate and chondroitin 6 sulfate using an enzyme-linked immunosorbent assay preoperatively and postoperatively on days 1 and 4, week 1, and 1 and 3 months.

RESULTS

The chondroitin 4 sulfate concentration remained unchanged from preoperative values. The chondroitin 6 sulfate concentration increased temporarily 1 day postoperatively and gradually decreased thereafter.

CONCLUSIONS

CS in tear fluids participates in wound healing after LASIK. Clarifying its role in tear fluids will contribute to improved LASIK outcomes.

Efficacy of two chondroitin sulfate ophthalmic solutions in the therapy of spontaneous chronic corneal epithelial defects and ulcerative keratitis associated with bullous keratopathy in dogs

OBJECTIVE

To determine the efficacy of two antimicrobial-chondroitin sulfate ophthalmic solutions in the therapy of spontaneous chronic corneal epithelial defects (SCCED) and ulcerative keratitis associated with bullous keratopathy in dogs.

ANIMALS STUDIED

Eighty dogs with SCCED and 14 dogs with ulcerative keratitis associated with bullous keratopathy.

PROCEDURE

Following manual debridement of nonadherent epithelium, dogs were treated topically with a chondroitin sulfate ophthalmic solution containing either tobramycin or ciprofloxacin. Patients were re-evaluated at 2-week intervals for 4 weeks.

RESULTS

After 2 weeks of treatment, 53.6% of eyes with SCCED and 17.6% of eyes with ulcerative keratitis associated with bullous keratopathy had healed. After 4 weeks of treatment, 81.0% of eyes with SCCED and 23.5% of eyes with ulcerative keratitis associated with bullous keratopathy had healed. There were no statistically significant differences in healing percentages between the tobramycin-chondroitin sulfate solution treatment groups and the ciprofloxacin-chondroitin sulfate solution treatment groups. Two dogs with SCCED, one treated with the tobramycin-chondroitin sulfate solution and the other treated with the ciprofloxacin-chondroitin sulfate solution, developed sterile corneal stromal abscesses during the study.

CONCLUSIONS

Topical therapy with an antimicrobial-chondroitin sulfate ophthalmic solution combined with manual debridement of nonadherent epithelium compares favorably with other published medical and surgical therapies for SCCED; however, these compounds are only equivocally more effective than therapy with manual debridement alone. These solutions appear to be ineffective in the treatment of ulcerative keratitis associated with bullous keratopathy. The significance of the two cases of corneal stromal abscessation is unknown at this time and warrants further investigation.

Hyaluronan synthase in trabecular meshwork cells

BACKGROUND/AIMS

Hyaluronan is present in the trabecular meshwork where it is involved in the pathophysiology of aqueous outflow environment. In this study, the expression and regulation of hyaluronan synthase (HAS), which is the enzyme synthesising hyaluronan, in trabecular meshwork cells were investigated.

METHODS

Cultured bovine trabecular meshwork cells (BTMCs) were used. HAS expression in BTMCs was examined by RT-PCR. The effects of transforming growth factor beta (TGF-beta) and platelet derived growth factor BB (PDGF-BB) on HAS expression in BTMCs were examined by quantitative RT-PCR. The HAS2 expression by TGF-beta and PDGF-BB at the protein level was also confirmed immunohistochemically. The production of hyaluronan from BTMCs was detected by high performance liquid chromatography (HPLC).

RESULTS

Three HAS isoforms were expressed in BTMCs at the mRNA level. Among HAS isoforms, only the expression of HAS2 mRNA was increased by the administration of TGF-beta or PDGF-BB. HAS2 upregulation by these growth factors was also confirmed at the protein level. Further, hyaluronan production from BTMCs was stimulated by TGF-beta or PDGF-BB.

CONCLUSION

Expression of HAS in trabecular meshwork may maintain the hyaluronan content in the aqueous outflow pathway. Its production is regulated by TGF-beta and PDGF-BB. The regulation of the expression of HAS in trabecular meshwork might be useful for modulating the aqueous outflow environment.

Effect of Hyaluronic Acid on Corneal Haze in a Photorefractive Keratectomy Experimental Model

PURPOSE

To evaluate the ability of topical hyaluronic acid to decrease corneal opacity after excimer laser photorefractive keratectomy (PRK) in hens.

METHODS

Twenty-four white hens underwent bilateral 193-nm excimer laser PRK to correct -9.00 D of myopia. One eye received postoperative treatment with topical 1% hyaluronic acid six times daily for 3 days; the other eye received phosphate buffered saline. Slit-lamp evaluation by a masked observer was performed for 6 months after PRK, and electron microscopy was carried out at the end of the study.

RESULTS

There were no significant differences in postoperative haze between the eyes treated with hyaluronic acid and those treated with phosphate buffered saline.

CONCLUSION

Topical administration of hyaluronic acid had no effect on the development of corneal haze following PRK in hens.

Analysis of liquid accumulated in the distended capsular bag in early postoperative capsular block syndrome

PURPOSE

To analyze the transparent liquid between the posterior lens capsule and the posterior chamber intraocular lens (PC IOL) in early postoperative capsular block syndrome and discuss the mechanism of posterior capsule distention.

SETTING

Department of Ophthalmology, Tokyo University School of Medicine, and Tokyo Research Institute, Seikagaku Corporation, Tokyo, Japan.

METHODS

This study evaluated 3 cases of capsular block syndrome presenting with transparent liquid in the distended capsular bag 1 day after cataract surgery. The transparent liquid material between the posterior capsule and PC IOL was aspirated and analyzed using high-performance liquid chromatography (HPLC). Also, sodium hyaluronate was diluted using a dialyzer to determine whether the aqueous humor was drawn into the capsular bag by an osmotic gradient across the capsule.

RESULTS

The elution time of the samples was almost the same as that of sodium hyaluronate 1.0% (Healon) The concentration of the samples ranged from 3.29 to 9. 01 mg/mL by HPLC analysis. The sodium hyaluronate absorbed the physiological salt solutions through the dialyzer and expanded to 1. 9 times its original volume.

CONCLUSIONS

These results indicate that the main ingredient of the transparent liquid in capsular bags is sodium hyaluronate and that the distention is caused by aqueous humor being drawn into the capsular bag by an osmotic gradient across the capsule when the capsulorhexis diameter is smaller than that of the PC IOL and by viscoelastic material retained and trapped in the bag intraoperatively.

Does chondroitin sulfate defend the human uterine cervix against ripening in threatened premature labor?

OBJECTIVE

This study was undertaken to investigate changes in chondroitin sulfate levels in the cervix and the physiologic role of chondroitin sulfate isomers in the process of cervical ripening.

STUDY DESIGN

Uterine cervical mucus samples were obtained from 57 women (7 nonpregnant women, 19 at preterm gestation, 9 at term gestation, 16 during the first stage of term labor, and 6 with threatened premature labor). Chondroitin sulfate isomer (chondroitin 0-sulfate, 4-sulfate, and 6-sulfate) concentrations in cervical mucus were measured by high-performance liquid chromatography. The effect of exogenous chondroitin sulfate on hyaluronidase activity in cervical mucus was evaluated by gel permeation chromatography of fluorolabeled hyaluronic acid.

RESULTS

Chondroitin sulfate concentrations in cervical mucus were increased significantly (P <. 05) in the threatened premature labor group compared with the preterm and term groups. However, the same finding was not observed in the first stage of term labor. Exogenous chondroitin sulfate inhibited hyaluronidase activity in mucus.

CONCLUSION

Chondroitin sulfate may defend against cervical ripening in threatened premature labor.

Antithrombotic activity of avian crown dermatan sulfate

The antithrombotic activity of dermatan sulfate from avian crown with the mean molecular weight of 38000 was compared to those from bovine intestine with the mean molecular weight of 16000 in vivo and in vitro. In an in vitro test, bovine intestine dermatan sulfate exhibited stronger effects on stimulation of heparin cofactor II and activation of Glu-plasminogen by tissue plasminogen activator. In vivo, avian crown dermatan sulfate more effectively prevented the development of thrombus in a rat deep vein thrombosis model. The measurement of plasma levels of these two kinds of dermatan sulfate revealed that avian crown dermatan sulfate circulated in higher concentration and longer duration than bovine intestine dermatan sulfate after intravenous administration to rats.

Accumulation of milky fluid: a late complication of cataract surgery

We describe 3 patients who presented with an accumulation of homogeneous milky fluid in the capsular bag several years after continuous curvilinear capsulorhexis, phacoemulsification, and posterior chamber intraocular lens (IOL) implantation. In each case, the entire edge of the anterior capsule opening was tightly attached to the peripheral IOL optic. The milky fluid was present in the closed chamber between the IOL optic and the posterior capsule. The fluid was sampled in 2 patients, and its concentration of sodium hyaluronate was determined by high-performance liquid chromatography. The concentration of sodium hyaluronate resembled that in normal aqueous humor. In 1 case, the protein concentration was measured and found to be elevated. Electrophoresis showed that human serum albumin was the main protein constituent. While the outcome was favorable in all 3 patients, this delayed complication of cataract surgery merits further study to clarify its etiology and pathogenesis.

Corneal cell proteins and ocular surface pathology

The cornea is a transparent and avascular tissue that functions as the major refractive structure for the eye. A wide variety of growth factors, chemokines, cytokines and their receptors are synthesized by corneal epithelial and stromal cells, and are found in tears. These molecules function in corneal wound healing and in inflammatory responses. Proteoglycans and glycoproteins are essential for normal corneal function, both at the air-epithelial interface and within the extracellular matrix. The ocular MUC mucins may play roles in forming the mucus layer of the tear film, in regulating tear film spread, and in inhibiting the adhesion of pathogens to the ocular surface. Lumican, keratocan and mimecan are the major keratan sulfate proteoglycans of the corneal stroma. They are essential, along with other proteoglycans and interfibrillar proteins, including collagens type VI and XII, for the maintenance of corneal transparency. Corneal epithelial cells interact with a specialized extracellular matrix structure, the basement membrane, composed of a specific subset of collagen type IV and laminin isoforms in addition to ubiquitous extracellular matrix molecules. Matrix metalloprotein-ases have been identified in normal corneal tissue and cells and may play a role in the development of ulcerative corneal diseases. Changes in extracellular matrix molecule localization and synthesis have been noted in other types of corneal diseases as well, including bullous keratopathy and keratoconus.

Role of chondroitin sulfate-hyaluronan interactions in the viscoelastic properties of extracellular matrices and fluids

The purpose of this study was to investigate the role of chondroitin sulfate-hyaluronan interactions in the viscoelastic properties of tissues and fluids, using capillary and cone-on-plate viscometers. Chondroitin sulfate markedly increased the viscosity of hyaluronan solutions at a wide range of hyaluronan mass (50-1900 kDa) under physiological conditions of pH, temperature, ionic strength and glycosaminoglycan concentration (0.5-40 mg/ml), although the viscosity of the chondroitin sulfate solutions themselves was very low. In the assay using a cone-on-plate viscometer, chondroitin sulfate increased the viscosity of hyaluronan solutions at various shear rates. At low shear rates, the viscosity of a chondroitin sulfate (5 mg/ml)-hyaluronan (0.5 mg/ml) mixture was about 40% of that of an aggrecan (5 mg/ml)-hyaluronan (0.5 mg/ml) mixture, and at 2.8-fold higher concentrations, chondroitin sulfate elicited the same effect on the viscosity of hyaluronan solutions (5 mg/ml) as an aggrecan monomer. In the presence of oscillatory motion, the addition of aggrecan increased the elasticity (storage) modulus G' and the viscosity (loss) modulus G" of hyaluronan solutions and markedly decreased the loss tangent G"/G' at frequencies corresponding to normal joint movements. In contrast, chondroitin sulfate had only a marginal effect on the loss tangent G"/G', although it increased G' and G". These findings demonstrated that chondroitin sulfate, as well as aggrecan, increases the viscosity of hyaluronan solutions, although chondroitin sulfate has less effect on the elasticity of hyaluronan solutions than that of aggrecan, and suggest that chondroitin sulfate may play an important physiological role in determining the viscoelastic properties of extracellular matrices and fluids.