Hyaluronan receptors in the human ocular surface: a descriptive and comparative study of RHAMM and CD44 in tissues, cell lines and freshly collected samples

Application frequency - key indicator for the efficiency of severe dry eye disease treatment - evidence for the importance of molecular weight of hyaluronan in lubricating agents

PURPOSE

Lubricant eye drops are the main therapeutic resource for dry eye disease (DED), with each drop representing the equivalent of ocular surface disease treatment. Thus, any reduction in the frequency of eye drop application reflects a degree of therapeutic success. Considering also the socioeconomic burden of DED, we investigated eye drop application frequency (DF) as a parameter to potentially track the success of therapy in severe DED. Hyaluronan (HA)-containing eye drops have become the first choice for tear substitution in many countries, and recent data indicate that the average molecular weight (Mw) of HA determines the therapeutic efficacy of such eye drops. This post-hoc subgroup analysis of a previously published multicentre prospective randomized open-label study, HYLAN M, is set out to compare the effects of very high Mw HA (hylan A) eye drops to comparator eye drops, containing lower Mw HA (control).

METHODS

Patients with severe DED (n = 47), recruited as part of the larger HYLAN M prospective, multicentre, open-label study, were randomized into two groups: hylan A and control group. In the hylan A group, 24 patients replaced their HA-containing eye drops with eye drops containing 0.15% hylan A, whereas the 23 control patients continued to use comparator HA eye drops. The DF was recorded daily by all participants over 8 weeks, and other subjective and objective parameters of DED were assessed at the time of inclusion (baseline), as well as at week 4 and 8.

RESULTS

There was a significant decrease in DF in the hylan A users between the baseline and week 4 (p = 0.004), remaining stable until week 8. Indeed, in contrast to the baseline, the hylan A group had a significantly lower DF than the control group at weeks 4 (p = 0.018) and 8 (p = 0.008). Likewise, the ocular surface disease index (OSDI) improved significantly between the time of inclusion and week 4 (p < 0.001) in hylan A users, remaining stable until week 8. The OSDI was similar in both groups at the baseline but it was significantly lower in the hylan A group than in the control group at week 4 (p = 0.002), remaining lower at week 8. Such a decrease in the DF and OSDI was not witnessed in the control group at any time point. The objective parameters assessed did not differ significantly within or between the two groups.

CONCLUSION

When treating severe DED, the DF can be significantly reduced by using very high Mw HA (3 MDa) lubricant eye drops, which better alleviate DED symptoms and decrease the OSDI scores. These drops not only provide an attractive and comfortable alternative for patients with severe DED but also offer the possibility of reducing the disease's socioeconomic burden, both for affected individuals and society as a whole.

A review on revolutionizing ophthalmic therapy: Unveiling the potential of chitosan, hyaluronic acid, cellulose, cyclodextrin, and poloxamer in eye disease treatments

Ocular disorders, encompassing both common ailments like dry eye syndrome and more severe situations for instance age-related macular degeneration, present significant challenges to effective treatment due to the intricate architecture and physiological barriers of the eye. Polysaccharides are emerging as potential solutions for drug delivery to the eyes due to their compatibility with living organisms, natural biodegradability, and adhesive properties. In this review, we explore not only the recent advancements in polysaccharide-based technologies and their transformative potential in treating ocular illnesses, offering renewed optimism for both patients and professionals but also anatomy of the eye and the significant obstacles hindering drug transportation, followed by an investigation into various drug administration methods and their ability to overcome ocular-specific challenges. Our focus lies on biological adhesive polymers, including chitosan, hyaluronic acid, cellulose, cyclodextrin, and poloxamer, known for their adhesive characteristics enhancing drug retention on ocular surfaces and increasing bioavailability. A detailed analysis of material designs used in ophthalmic formulations, such as gels, lenses, eye drops, nanofibers, microneedles, microspheres, and nanoparticles, their advantages and limitations, the potential of formulations in improving therapeutic outcomes for various eye conditions. Moreover, we underscore the discovery of novel polysaccharides and their potential uses in ocular drug delivery.

Enhancing the hypotensive effect of latanoprost by combining synthetic phosphatidylcholine liposomes with hyaluronic acid and osmoprotective agents

The first line of glaucoma treatment focuses on reducing intraocular pressure (IOP) through the prescription of topical prostaglandin analogues, such as latanoprost (LAT). Topical ophthalmic medicines have low bioavailability due to their rapid elimination from the ocular surface. Nanotechnology offers innovative ways of enhancing the ocular bioavailability of antiglaucoma agents while reducing administration frequency. This study aims to combine LAT-loaded synthetic phosphatidylcholine liposomes with hyaluronic acid (0.2% w/v) and the osmoprotectants betaine (0.40% w/v) and leucine (0.90% w/v) (LAT-HA-LIP) to extend the hypotensive effect of LAT while protecting the ocular surface. LAT-HA-LIP was prepared as a mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-dimyristoyl-sn-glycero-3-phosphocholine, cholesterol and α-tocopherol acetate. LAT-HA-LIP exhibited high drug-loading capacity (104.52 ± 4.10%), unimodal vesicle sizes (195.14 ± 14.34 nm) and a zeta potential of -13.96 ± 0.78 mV. LAT-HA-LIP was isotonic (284.00 ± 1.41 mOsm L-1), had neutral pH (7.63 ± 0.01) and had suitable surface tension (44.07 ± 2.70 mN m-1) and viscosity (2.69 ± 0.15 mPa s-1) for topical ophthalmic administration. LAT-HA-LIP exhibited optimal in vitro tolerance in human corneal and conjunctival epithelial cells. No signs of ocular alteration or discomfort were observed when LAT-HA-LIP was instilled in albino male New Zealand rabbits. Hypotensive studies revealed that, after a single eye drop, the effect of LAT-HA-LIP lasted 24 h longer than that of a marketed formulation and that relative ocular bioavailability was almost three times higher (p < 0.001). These findings indicate the potential ocular protection and hypotensive effect LAT-HA-LIP offers in glaucoma treatment.

Carbohydrate polymer-based bioadhesive formulations and their potentials for the treatment of ocular diseases: A review

Eyes are directly exposed to the outer environment and susceptible to infections, leading to various ocular disorders. Local medication is preferred to treat eye diseases due to its convenience and compliance. However, the rapid clearance of the local formulations highly limits the therapeutic efficacy. In the past decades, several carbohydrate bioadhesive polymers (CBPs), such as chitosan and hyaluronic acid, have been used in ophthalmology for sustained ocular drug delivery. These CBP-based delivery systems have improved the treatment of ocular diseases to a large extent but also caused some undesired effects. Herein, we aim to summarize the applications of some typical CBPs (including chitosan, hyaluronic acid, cellulose, cyclodextrin, alginate and pectin) in treating ocular diseases from the general view of ocular physiology, pathophysiology and drug delivery, and to provide a comprehensive understanding of the design of the CBP-based formulations for ocular use. The patents and clinical trials of CBPs for ocular management are also discussed. In addition, a discussion on the concerns of CBPs in clinical use and the possible solutions is presented.

Evaluation of Conventional and Hyaluronic Acid-Coated Thymoquinone Liposomes in an In Vitro Model of Dry Eye

Dry eye disease (DED) is a common ocular disorder characterized by an inadequate lubrication of the eye by tears leading to inflammation and the alteration of the ocular surface. Current treatments are often limited due to their side effects and ineffectiveness. Thymoquinone (TQ) is a natural compound present in the essential oil of Nigella sativa L., with anti-inflammatory and antioxidant activities. In this study, conventional and hyaluronic acid-coated liposomes were developed to improve TQ activity at ocular level. In the present study, the cytoprotective effects of TQ or TQ liposomes were assessed against oxidative and inflammatory processes in human corneal epithelial cells (HCE-2). Hyperosmolarity conditions (450 mOsm) were used as a model of DED. Interleukin-1β (IL-1β), Interleukin-6 (IL-6) and tumor necrosis factor (TNFα) were quantified by quantitative real-time polymerase chain reaction (RT-qPCR); COX-2 and Phospho-NF-κB p65 (p-p65) by Western blotting (WB). Moreover, the mitochondrial reactive oxygen species (mtROS) levels were measured by MitoSOX assay. The hyperosmotic treatment induced a significant increase of the proinflammatory genes and proteins expression that were significantly decreased in the liposomes-treated cells. The coincubation with hyaluronic acid-coated liposomes significantly reverted the increase of mtROS production, evidently stimulated by the hyperosmotic stress. Our data suggest that TQ-loaded liposomes have potential as a therapeutic agent in dry eye disease, improving the TQ efficacy.

The Effect of High Molecular Weight Hyaluronic Acid and Latanoprost Eyedrops on Tear Functions and Ocular Surface Status in C57/BL6 Mice

Anti-glaucoma eye drop treatment often induces ocular surface problems, including dry eyes, and may be associated with poor medication compliance. This study aimed to investigate the effects of a novel high molecular weight hyaluronic acid and Latanoprost eye drop on intraocular pressure, as well as the tear function and ocular surface alterations in wild type mice, comparing the results with the mice receiving commercially available Latanoprost eye drops and mice receiving no treatment. The mice were divided into three groups: Group I, control group (no treatment group); Group II, commercial Latanoprost eye drop (LP); and Group III, Comfort Shield (CS) + Latanoprost (LP) eye drop (CS + LP). The CS + LP eye drop group had an IOP lowering effect comparable to the commercial LP eye drop group. The mice receiving LP eye drops had significantly worse corneal staining scores, lesser goblet cell density(GCD), higher numbers of CD45+ staining cells, significantly higher tear film concentrations of IL-6 and IL1-b, and a significantly lower expression of corneal ZO-1 mRNA compared with the mice receiving CS + LP 7 days after eye drop instillations (p < 0.05). In conclusion, the new CS + LP formulation appeared to induce less inflammation, less corneal vital staining, and a better barrier status with an IOP lowering effect comparable to the commercial LP eye drops.

Hyaluronic Acid: Its Versatile Use in Ocular Drug Delivery with a Specific Focus on Hyaluronic Acid-Based Polyelectrolyte Complexes

Extensive research is currently being conducted into novel ocular drug delivery systems (ODDS) that are capable of surpassing the limitations associated with conventional intraocular anterior and posterior segment treatments. Nanoformulations, including those synthesised from the natural, hydrophilic glycosaminoglycan, hyaluronic acid (HA), have gained significant traction due to their enhanced intraocular permeation, longer retention times, high physiological stability, inherent biocompatibility, and biodegradability. However, conventional nanoformulation preparation methods often require large volumes of organic solvent, chemical cross-linkers, and surfactants, which can pose significant toxicity risks. We present a comprehensive, critical review of the use of HA in the field of ophthalmology and ocular drug delivery, with a discussion of the physicochemical and biological properties of HA that render it a suitable excipient for drug delivery to both the anterior and posterior segments of the eye. The pivotal focus of this review is a discussion of the formation of HA-based nanoparticles via polyelectrolyte complexation, a mild method of preparation driven primarily by electrostatic interaction between opposing polyelectrolytes. To the best of our knowledge, despite the growing number of publications centred around the development of HA-based polyelectrolyte complexes (HA-PECs) for ocular drug delivery, no review articles have been published in this area. This review aims to bridge the identified gap in the literature by (1) reviewing recent advances in the area of HA-PECs for anterior and posterior ODD, (2) describing the mechanism and thermodynamics of polyelectrolyte complexation, and (3) critically evaluating the intrinsic and extrinsic formulation parameters that must be considered when designing HA-PECs for ocular application.

Potential Therapeutic Role of Pituitary Adenylate Cyclase-Activating Polypeptide for Dry Eye Disease

Dry eye disease (DED) is caused by a reduction in the volume or quality of tears. The prevalence of DED is estimated to be 100 million in the developed world. As aging is a risk factor for DED, the prevalence of DED is expected to grow at a rapid pace in aging populations, thus creating an increased need for new therapies. This review summarizes DED medications currently in clinical use. Most current medications for DED focus on stimulating tear secretion, mucin secretion, or suppressing inflammation, rather than simply replenishing the ocular surface with moisture to improve symptoms. We recently reported that the neuropeptide PACAP (pituitary adenylate cyclase-activating polypeptide) induces tear secretion and suppresses corneal injury caused by a reduction in tears. Moreover, it has been reported that a PACAP in water and a 0.9% saline solution at +4 °C showed high stability and achieved 80-90% effectiveness after 2 weeks of treatment. These results reveal PACAP as a candidate DED medication. Further research on the clinical applications of PACAP in DED is necessary.

Preparation of Liposomal Formulations for Ocular Delivery of Thymoquinone: In Vitro Evaluation in HCEC-2 e HConEC Cells

Thymoquinone (TQ) is the main constituent of Nigella sativa L. essential oil. In vitro studies have shown its protective effect against H₂O₂-induced oxidative stress in human retinal pigment epithelium cells, and in vivo experiments have demonstrated its effect in decreasing corneal neovascularization and reducing the inflammation in an experimental dry eye model in mice. Its therapeutic use is limited by poor bioavailability, low solubility, and scarce permeability. In this study, two liposomal formulations have been developed, both of which consist of phosphatidylcholine and Plurol Oleique, a liquid lipid, and one of which is coated with 0.1% w/v hyaluronic acid (HA) to increase both TQ solubility and its ocular therapeutic potential. Each formulation has a size <200 nm and an EE% around 70%, determined by scattering techniques and the HPLC-DAD analytical method, respectively, and they result in a 2-fold increase in TQ solubility. HA-coated liposomes are stable over 2 months at +4 °C, and coated and uncoated liposomes present a gradual and prolonged release of TQ. Two cell lines, human corneal epithelial cells (HCEC-2) and human conjunctival epithelial cells (HConEC) were used to investigate the safety of the liposomal formulations. Uptake studies were also performed using fluorescent liposomes. Both liposomes and, in particular, HA-coated liposomes reduce the TQ toxicity observed at high doses in both HCEC-2 and HConEC cells, and both formulations increase the absorption at the cellular level and especially at the nucleus level, with a more pronounced effect for HA-coated liposomes.

Correlation of Soluble CD44 Expression in Saliva and CD44 Protein in Oral Leukoplakia Tissues

The aim of this study was to determine whether and how pan-CD44 protein expression in leukoplakia tissues correlates with positive SolCD44 test presence and their role in oral leukoplakia. SolCD44 and total protein expression in saliva were determined using an OncAlert^® Oral Cancer Rapid test. Comparison of paired associations of total protein, SolCD44, mean number of CD44 expressed epithelial layers in leukoplakia tissue, and macrophages below the basement membrane between control group and patients with leukoplakia showed statistically significant results (p < 0.0001). It is shown that the total protein indicates low or elevated risk of possible malignant transformation processes in leukoplakia. Statistically significant differences between higher total protein level and clinical forms of oral leukoplakia (p < 0.0001), as well as CD44-labeled epithelial cell layer decrease (p < 0.0001), were found. This possibly points to the onset of the stemness loss in leukoplakia tissue. CD9 antigen expression in the exosomes of the oral epithelium explained the intercellular flow of SolCD44 and other fluids in the leukoplakia area. We conclude that the OncAlert^® Oral Cancer Rapid test is a valuable screening method in daily clinical practice, in terms of complementing clinical diagnostics methods and to assess the potential for early malignancy.

Detection of TSG-6-like protein in human corneal epithelium. Simultaneous presence with CD44 and hyaluronic acid

INTRODUCTION

Tumor necrosis factor-inducible gene 6 protein (TSG-6) is member of the hyaluronan-binding protein family (hyaladherins) to which CD44 also belongs. Inflammatory mediators such as tumor necrosis factor α (TNF-α) and interleukin-1 (IL-1) stimulate TSG-6 production. Recently, however, externally applied TSG-6 has been shown to be effective in the treatment of inflammatory dry eye. On the other hand, it is still unknown whether TSG-6 is naturally present in human corneal epithelium.

MATERIAL AND METHODS

Corneal sections of 15 eyes enucleated for posterior segment uveal melanoma were immunohistochemically stained for hyaluronic acid (HA), CD44, and TSG-6.

RESULTS

Throughout the corneal epithelium of all sections, CD44 and hyaluronic acid were detected most intensely in the basal epithelial layer. Whereas the presence of HA was intense even in the cytoplasm of the cells, CD44 was located predominantly at the cell membranes. The intensity of the specific staining decreased towards the surface, where CD44 was barely detectable. Hyaluronic acid was, on the other hand, detectable in the extracellular matrix and cells, even at the surface. TSG-6 like immunoreactivity was detected in all sections in a pattern similar to CD44 but much more distinct and intense, with a marked localization in the cell membranes and intercellular spaces, i.e., extracellular matrix. TSG-6 like immunoreactivity was clearly detectable through all cell layers of the corneal epithelium. All control sections were negative.

DISCUSSION

Tumor necrosis factor-inducible gene 6 (TSG-6)- like protein is present in human corneal epithelium. It might be a natural component of this tissue which is constantly exposed and mechanically traumatized, and displays localization with similarities to that of CD44. The immunohistological detection of HA as major component of the ECM and epithelial tissue only confirms the results of earlier studies. However, the simultaneous presence and colocalization of CD44 and TSG-6, both HA-binding proteins, requires further investigation of the individual role, regulation and interaction of this system.

CONCLUSION

The detection of TSG-6 in human corneal epithelium in the absence of inflammation underlines the importance of normal mechanical forces on the gene expression and regulation of this protein in ocular surface tissues. Given the relationship between inflammation and the protein, TSG-6 may be a major unknown and underestimated player in the regulation of the inflammation encountered in the presence of ocular surface desiccation and dry eye disease.

Selecting Appropriate Reference Genes for Quantitative Real-Time Polymerase Chain Reaction Studies in Isolated and Cultured Ocular Surface Epithelia

The introduction of tissue engineering has allowed scientists to push the boundaries and treat seriously damaged ocular surface epithelia. They have managed to do this through the development of biological substitutes that restore, maintain or improve tissue function. To ensure the generation of a therapeutically safe and effective graft, knowledge on the transcriptional profile of native and cultured ocular surface epithelia is of undeniable value. Gene expression studies are, however, only as reliable as their proper selection of internal reaction controls or reference genes. In this study, we determined the expression stability of a number of reference genes: 18s rRNA, ACTB, ATP5B, CyC1, EIF4A2, GAPDH, RPL13A, SDHA, TOP1, UBC, and YWHAZ in primary isolates as well as in ex vivo cultured ocular surface epithelia explants (day 0 and/or day 14). Expression stability of the reference genes was assessed with both the geNorm and NormFinder software that use a pairwise comparison and a model-based approach, respectively. Our results extend the general recommendation of using multiple reference genes for normalization purposes to our model systems and provide an overview of several references genes that are likely to be stable in similar culture protocols.

Recent advance of nanoparticle-based topical drug delivery to the posterior segment of the eye

INTRODUCTION

Considering that the number of patients afflicted by posterior eye diseases is increasing, effective drug delivery is currently in high clinical demand. Topical administration has been identified as the preferred option, while sufferingfrom multiple barriers. The development of nanoparticle-based drug delivery system provides an option, which would enhance the drug permeability across the barriers and achieve the desired drug level in the targeted tissue.

AREAS COVERED

This review highlights the barrier to the posterior segment of the eye via topical administration. The up-to-date development of lipid nanoparticles, liposomes, emulsions, spanlastics, micelles, polymeric nanoparticles, layered double hydroxides (LDH), dendrimers, cyclodextrins(CDs), and prodrugs are summarized. Moreover, nanocarriers currently in clinical trials for posterior segment diseases have been discussed.

EXPERT OPINION

Topical nanoparticle-based drug delivery systems have demonstrated significant progress. An ideal formulation should prolong retention time on the surface, enhance drug permeability through the ocular tissues, and efficiently deliver drugs to the targeted site. To design the rational targeting nanoparticle-based drug delivery system, a better understanding of the distribution of transporters and receptors on the eye is required. Ultimately, there is an urgent need to develop targeting hybrid drug delivery systems with the combination of the advantages of several nanocarriers.

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.

Hyaluronate Acid-Dependent Protection and Enhanced Corneal Wound Healing against Oxidative Damage in Corneal Epithelial Cells

Purpose. To evaluate the effects and mechanism of exogenous hyaluronate (HA) in promoting corneal wound healing. Methods. Human corneal epithelial cells (HCECs) were incubated with different concentrations of HA to evaluate their efficiency in promoting cell migration and their modulation of repair factors. After inducing hyperosmolar conditions, the cell morphologies, cell apoptosis, and expression levels of TNF-α and MMP-9 were detected to assess the protective role of HA. Corneal epithelium-injured rat models were established to test the therapeutic effects of 0.3% HA. Then, the wound healing rates, the RNA expression levels of inflammatory cytokines, and repair factors were examined. Results. HCECs in the 0.03% and 0.3% HA groups showed fewer morphological alterations and lower rates of cell apoptosis following preincubation with HA under hyperosmolar conditions, as well as the expression levels of MMP-9 and TNF-α. In the rat model, the areas of fluorescein staining in the corneas of 0.3% HA group were significantly smaller than the control group. The expression levels of IL-1β and MMP-9 were decreased, while CD44 and FN were increased in the 0.3% HA group. Conclusion. HA enhanced corneal epithelial cell wound healing by promoting cell migration, upregulating repair responses, and suppressing inflammatory responses.

Thrombospondin-1 induces differential response in human corneal and conjunctival epithelial cells lines under in vitro inflammatory and apoptotic conditions

Recently, thrombospondin-1 (TSP-1) has been reported to be critical for maintaining a healthy ocular surface. The purpose of the study was to characterize the expression of TSP-1 and of its receptors CD36 and CD47 in corneal and conjunctival epithelial cells and determine the effect of exogenous TSP-1 treatment on these cells, following the induction of inflammation- and apoptosis-related changes. The expression of TSP-1, CD36 and CD47 by corneal and conjunctival cell lines was firstly characterized by ELISA, immunofluorescence analysis, Western blotting and reverse transcription polymerase chain reaction (RT-PCR). Benzalkonium chloride (BAC) exposure for 5 or 15 min was used as pro-inflammatory and pro-apoptotic stimulus for corneal or conjunctival epithelial cells, respectively. To analyze inflammation and apoptosis-related changes, IL-6 and TGF-β2 secretion determined by ELISA was used as inflammatory markers, while activated caspase-3/7 levels and cell viability, determined by CellEvent™ Caspase-3/7 Green Detection Reagent and XTT cytotoxicity assay, respectively, were used as apoptotic markers. Changes in CD36 and CD47 mRNA expression were quantified by real time RT-PCR. Corneal epithelial cells secreted and expressed higher protein levels of TSP-1 than conjunctival epithelial cells, although TSP-1 mRNA expression levels were similar and had lower CD36 and CD47, both at protein and mRNA levels. Both cell lines responded to exogenous TSP-1 treatment increasing CD36 at protein and mRNA levels. Blocking experiments revealed a predominance of TSP-1/CD47 rather than TSP-1/CD36 interactions to up-regulate CD36 levels in conjunctival epithelial cells, but not in corneal epithelial cells. BAC exposure increased IL-6 secretion and caspase-3/7 levels and decreased cell viability in both, corneal and conjunctival epithelial cells. Moreover, BAC exposure increased latent TGF-β2 levels in conjunctival epithelial cells. Interestingly, CD36 mRNA expression was down-regulated after BAC exposure in both cell lines. Exogenous TSP-1 treatment reduced TGF-β2 up-regulated levels by BAC exposure in conjunctival epithelial cells and less pronounced reduced IL-6 in BAC-exposed corneal epithelial cells. The effect on CD36 and CD47 regulation was less pronounced or even opposite depending on the inflammation- and apoptosis-related markers tested. Our results show evidence of the capacity of corneal and conjunctival epithelial cells to respond to TSP-1 via CD36 or CD47. Experimental simulation of inflammation- and apoptosis-related conditions changed the effects differentially elicited by TSP-1 on corneal and conjunctival epithelial cells, suggesting an unexpected and relevant contribution of TSP-1 on ocular surface homeostasis regulation.

CD44 and RHAMM hyaluronan receptors in human ocular surface inflammation

BACKGROUND

CD44 and RHAMM hyaluronan (HA) receptors have been studied in several systemic diseases such as osteoarthritis and cancer. However, not too much is known about their role in ocular surface disorders. The purpose of this research was to determine if CD44 and RHAMM are implicated in human ocular surface inflammation.

METHODS

Upper tarsal conjunctival epithelial samples from patients with active ocular surface inflammation (n = 17) and healthy controls (n = 14) were recovered by brush cytology. Patients were evaluated by an ophthalmologist and classified in different groups according to the etiology (immune atopic diseases or immune non-atopic diseases) and inflammation intensity (mild/moderate or severe). CD44, RHAMM, and p53 mRNAs were measured using real-time PCR.

RESULTS

CD44, RHAMM, and p53 mRNAs were detected in all samples. In immune atopic diseases, higher levels of CD44 and RHAMM mRNAs were present, reaching a 300 % increase for RHAMM in severe inflammation (p < 0.001). In contrast, in immune non-atopic diseases, the HA receptors were downregulated. CD44 tended to decrease up to 30 % in severe patients (p = 0.06), and RHAMM decreased 40 % in severe inflammation (p = 0.021).

CONCLUSIONS

RHAMM may be implicated in severe ocular surface inflammation affecting the upper tarsal conjunctiva.

The Histochemistry and Cell Biology compendium: a review of 2012

The year 2012 was another exciting year for Histochemistry and Cell Biology. Innovations in immunohistochemical techniques and microscopy-based imaging have provided the means for advances in the field of cell biology. Over 130 manuscripts were published in the journal during 2012, representing methodological advancements, pathobiology of disease, and cell and tissue biology. This annual review of the manuscripts published in the previous year in Histochemistry and Cell Biology serves as an abbreviated reference for the readership to quickly peruse and discern trends in the field over the past year. The review has been broadly divided into multiple sections encompassing topics such as method advancements, subcellular components, extracellular matrix, and organ systems. We hope that the creation of this subdivision will serve to guide the reader to a specific topic of interest, while simultaneously providing a concise and easily accessible encapsulation of other topics in the broad area of Histochemistry and Cell Biology.