Arabinogalactan and hyaluronic acid in ophthalmic solution: Experimental effect on xanthine oxidoreductase complex as key player in ocular inflammation (in vitro study)

Correlation between gout and dry eye disease

BACKGROUND

Gout is a common form of inflammatory arthritis that can cause a number of serious complications. Complications are common in patients with gout and complicate their management and disease outcome. The recent literature has reported that an increasing number of gout patients are presenting with dry eye symptoms. However, until now, the link between gout and dry eye disease has not been clearly defined. (It is unclear whether the two conditions simply co-exist, whether there are common risk factors, or whether dry eye disease is a complication of gout.) METHODS: A thorough literature search was conducted in the PubMed database to summarize the most recent information on the correlation between gout and dry eye disease and to explore the potential relationship between the pathogenesis of the two. (Objective: Therefore, in this paper, we review the recent literature on the correlation between gout and dry eye disease and explore the potential association between the pathogenesis of both.) RESULTS: Studies in the last five years have shown a correlation between gout and dry eye, i.e., gout is associated with an increased risk of dry eye. The NLRP3-IL-1β signaling pathway may be a potential mechanism for the combination of gout and dry eye disease; factors such as high blood uric acid and xanthine oxidase activation in gout patients may aggravate the development of dry eye disease; reducing the use of visual display terminals; reducing or abstaining from alcohol consumption; and moderate coffee intake may effectively prevent gout and dry eye disease.

CONCLUSIONS

It is an undisputed fact that many gout patients present with dry eye manifestations that seriously affect the quality of life of gout patients, and early detection and treatment of dry eye in gout patients are crucial.

Arabinogalactan Alleviates Lipopolysaccharide-Induced Intestinal Epithelial Barrier Damage through Adenosine Monophosphate-Activated Protein Kinase/Silent Information Regulator 1/Nuclear Factor Kappa-B Signaling Pathways in Caco-2 Cells

Intestinal epithelial barrier (IEB) damage is an important aspect in inflammatory bowel disease (IBD). The objective of this study was to explore the protective effects and mechanisms of arabinogalactan (AG) on lipopolysaccharide (LPS)-stimulated IEB dysfunction. The results show that AG (1, 2, and 5 mg/mL) mitigated 100 μg/mL LPS-stimulated IEB dysfunction through increasing transepithelial electrical resistance (TEER), reducing fluorescein isothiocyanate (FITC)-dextran (4 kDa) flux, and up-regulating the protein and mRNA expression of tight junction (TJ) proteins (Claudin-1, Zonula occludens-1 (ZO-1) and Occludin). In addition, AG ameliorated LPS-stimulated IEB dysfunction by reducing interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and IL-1β levels, decreasing the reactive oxygen species (ROS) level, increasing superoxide dismutase (SOD) activity, increasing the glutathione (GSH) level, and decreasing the levels of malondialdehyde (MDA) and intracellular calcium ([Ca2+]i). Furthermore, 2 mg/mL AG up-regulated the expression of silent information regulator 1 (SIRT1), the phosphorylated adenosine monophosphate-activated protein kinase (AMPK), and peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and inhibited the phosphorylation of nuclear factor kappa-B (NF-κB) and the inhibitor of NF-κBα (IκBα). Therefore, AG could maintain IEB integrity by activating AMPK/SIRT1 and inhibiting the NF-κB signaling pathway. In conclusion, AG can regulate the AMPK/SIRT1/NF-κB signaling pathway to reduce inflammation and oxidative stress, thus alleviating LPS-stimulated IEB damage.

Hyaluronic acid in the treatment of dry eye disease

Dry eye disease (DED) is a highly prevalent and debilitating condition affecting several hundred million people worldwide. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan commonly used in the treatment of DED. This review aims to critically evaluate the literature on the safety and efficacy of artificial tears containing HA used in DED treatment. Literature searches were conducted in PubMed, including MEDLINE, and in Embase via Ovid with the search term: "(hyaluronic acid OR hyaluronan OR hyaluronate) AND (dry eye OR sicca)". A total of 53 clinical trials are included in this review, including eight placebo-controlled trials. Hyaluronic acid concentrations ranged from 0.1% to 0.4%. Studies lasted up to 3 months. A broad spectrum of DED types and severities was represented in the reviewed literature. No major complications or adverse events were reported. Artificial tears containing 0.1% to 0.4% HA were effective at improving both signs and symptoms of DED. Two major gaps in the literature have been identified: 1. no study investigated the ideal drop frequency for HA-containing eyedrops, and 2. insufficient evidence was presented to recommend any specific HA formulation over another. Future investigations assessing the optimal drop frequency for different concentrations and molecular weights of HA, different drop formulations, including tonicity, and accounting for DED severity and aetiology are essential for an evidence-based, individualized approach to DED treatment.

Hyaluronic Acid in Biomedical Fields: New Trends from Chemistry to Biomaterial Applications

The aim of this review is to give an updated perspective about the methods for chemical modifications of hyaluronic acid (HA) toward the development of new applications in medical devices and material engineering. After a brief introduction on chemical, structural and biological features of this important natural polysaccharide, the most important methods for chemical and physical modifications are disclosed, discussing both on the formation of new covalent bonds and the interaction with other natural polysaccharides. These strategies are of paramount importance in the production of new medical devices and materials with improved properties. In particular, the use of HA in the development of new materials by means of additive manufacturing techniques as electro fluid dynamics, i.e., electrospinning for micro to nanofibres, and three-dimensional bioprinting is also discussed.

Interpenetrating polymeric network (IPNs) in ophthalmic drug delivery: Breaking the barriers

To maintain the therapeutic drug concentration for a prolonged period of time in aqueous and vitreous humor is primary challenge for ophthalmic drug delivery. Majority of the locally administered drug into the eye is lost as to natural reflexes like blinking and lacrimation resulting in the short span of drug residence. Consequently, less than 5% of the applied drug penetrate through the cornea and reaches the intraocular tissues. The major targets for optimal ophthalmic drug delivery are increasing drug residence time in cul-de-sac of the eye, prolonging intraocular exposure, modulating drug release from the delivery system, and minimizing pre-corneal drug loss. Development of in situ gel, contact lens, intraocular lens, inserts, artificial cornea, scaffold, etc., for ophthalmic drug delivery are few approaches to achieve these major targeted objectives for delivering the drug optimally. Interpenetrating polymeric network (IPN) or smart hydrogels or stimuli sensitive hydrogels are the class of polymers that can help to achieve the targets in ophthalmic drug delivery due to their versatility, biocompatibility and biodegradability. These novel ''smart" materials can alter their molecular configuration and result in volume phase transition in response to environmental stimuli, such as temperature, pH, ionic strength, electric and magnetic field. Hydrogel and tissue interaction, mechanical/tensile properties, pore size and surface chemistry of IPNs can also be modulated for tuning the drug release kinetics. Stimuli sensitive IPNs has been widely exploited to prepare in situ gelling formulations for ophthalmic drug delivery. Low refractive index hydrogel biomaterials with high water content, soft tissue-like physical properties, wettability, oxygen, glucose permeability and desired biocompatibility makes IPNs versatile candidate for contact lenses and corneal implants. This review article focuses on the exploration of these smart polymeric networks/IPNs for therapeutically improved ophthalmic drug delivery that has unfastened novel arenas in ophthalmic drug delivery.

A Scoping Review on the Therapeutic Potential of Resin From the Species Larix decidua Mill. [Pinaceae] to Treat Ulcerating Wounds

Malignant ulcerating wounds or neoplastic lesions are a considerable burden for patients suffering from advanced cancer. These wounds have no effective treatment and are very difficult to manage. The present review summarizes evidence in support of a hypothesis put forward in anthroposophic medicine, which suggests a beneficial role of resin from the species Larix decidua Mill. [Pinaceae] for treating such wounds. A systematic search strategy was performed using the databases PubMed, EMBASE and SciFinder. The included publications described the chemical composition of this species, as well as in vitro, in vivo, and ex vivo experiments using plant extracts and isolated compounds. The results show that among the phytochemical classes, terpenoids were the major components of this species, especially in the resin. The summarized biological experiments revealed antimicrobial, antioxidant and anti-inflammatory effects, with promising potential for the extracts and isolated compounds. However, the molecular mechanisms and toxicological effects are as of yet not conclusively evaluated. From the data of our study, we can conclude that L. decidua might indeed have a promising potential for the treatment of malignant wounds, but definitive information that can prove its effectiveness is still lacking. We therefore suggest that future efforts should be dedicated to the evaluation of L. decidua resin's therapeutic use considering its antiseptic action and proposed wound healing properties.

Synergistic Properties of Arabinogalactan (AG) and Hyaluronic Acid (HA) Sodium Salt Mixtures

The properties of mixtures of two polysaccharides, arabinogalactan (AG) and hyaluronic acid (HA), were investigated in solution by the measurement of diffusion coefficients D of water protons by DOSY (Diffusion Ordered SpectroscopY), by the determination of viscosity and by the investigation of the affinity of a small molecule molecular probe versus AG/HA mixtures in the presence of bovine submaxillary mucin (BSM) by 1HNMR spectroscopy. Enhanced mucoadhesive properties, decreased mobility of water and decreased viscosity were observed at the increase of AG/HA ratio and of total concentration of AG. This unusual combination of properties can lead to more effective and long-lasting hydration of certain tissues (inflamed skin, dry eye corneal surface, etc.) and can be useful in the preparation of new formulations of cosmetics and of drug release systems, with the advantage of reducing the viscosity of the solutions.

Hyaluronan as a Prominent Biomolecule with Numerous Applications in Medicine

Hyaluronan (HA) is a natural glycosaminoglycan present in many tissues of all vertebrates. HA has various biological functions, which are dependent on its molar mass. High-molar-mass HA has anti-angiogenic, immunosuppressive and anti-inflammatory properties, while low-molar-mass HA has opposite effects. HA has also antioxidative properties, however on the other hand it can be readily degraded by reactive oxygen species. For many years it has been used in treatment of osteoarthritis, cosmetics and in ophthalmology. In the last years there has been a growing interest of HA to also be applied in other fields of medicine such as skin wound healing, tissue engineering, dentistry and gene delivery. In this review we summarize information on modes of HA administration, properties and effects of HA in various fields of medicine including recent progress in the investigation of HA.

In vitro amoebicidal effects of arabinogalactan-based ophthalmic solution

The main corneal infections reported worldwide are caused by bacteria and viruses but, recently, the number of Acanthamoeba keratitis (AK) cases has increased. Acanthamoeba genus is an opportunistic free living protozoa widely distributed in environmental and clinical sources, with two life-cycle stages: the trophozoite and the cyst. AK presents as primary symptoms eye redness, epithelial defects, photophobia and intense pain. An early diagnosis and an effective treatment are crucial to avoid blindness or eye removal but, so far, there is no established treatment to this corneal infection. Diverse research studies have reported the efficacy of commercialized eye drops and ophthalmic solutions against the two life cycle stages of Acanthamoeba strains, that usually present preservatives such as Propylene Glycol of Benzalkonium chloride (BAK). These compounds present toxic effects in corneal cells, favouring the inflammatory response in the so sensitive eye tissue. In the present work we have evaluated the efficacy of nine proprietary ophthalmic solutions with and without preservatives (ASDA Dry Eyes Eyedrops, Miren®, ODM5®, Ectodol®, Systane® Complete, Ocudox®, Matrix Ocular®, Alins® and Coqun®) against the two life cycle stages of three Acanthamoeba strains. Our work has demonstrated the high anti-Acanthamoeba activity of Matrix Ocular®, which induces the programmed cell death mechanisms in Acanthamoeba spp. trophozoites. The high efficacy and the absence of ocular toxic effects of Matrix Ocular®, evidences the use of the Arabinogalactan derivatives as a new source of anti-AK compounds.

Versatile Use of Chitosan and Hyaluronan in Medicine

Chitosan is industrially acquired by the alkaline N-deacetylation of chitin. Chitin belongs to the β-N-acetyl-glucosamine polymers, providing structure, contrary to α-polymers, which provide food and energy. Another β-polymer providing structure is hyaluronan. A lot of studies have been performed on chitosan to explore its industrial use. Since chitosan is biodegradable, non-toxic, bacteriostatic, and fungistatic, it has numerous applications in medicine. Hyaluronan, one of the major structural components of the extracellular matrix in vertebrate tissues, is broadly exploited in medicine as well. This review summarizes the main areas where these two biopolymers have an impact. The reviewed areas mostly cover most medical applications, along with non-medical applications, such as cosmetics.