The Protective Role of Hyaluronic Acid in Cr(VI)-Induced Oxidative Damage in Corneal Epithelial Cells

Trace Element Concentration in the Blood and Aqueous Humor of Subjects with Eye Cataract

Cataract, characterized by the opacification of the lens, is the leading cause of reversible blindness and visual impairment globally. The study aims to investigate the role of trace elements such as Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn in the development and severity of cataract. Elements were quantified by inductively coupled plasma mass spectrometry in blood and aqueous humor of 32 cataract cases and 27 controls living in the Latium region, Italy. The association between element concentration in blood and aqueous humor and cataract severity, gender, and age of subjects were also assessed. Results showed Cr levels significantly elevated in both blood and aqueous humor of cataract cases, with concentrations that increased with cataract severity. In addition, blood Pb levels were significantly higher in older cases and positively correlated with the age of cataract cases, while blood Co and Cu levels negatively correlated with cataract severity, suggesting changes in the levels of these elements. In conclusion, this study provides evidence of the involvement of specific elements in cataract development and severity, and the findings highlighted important avenues for future research. Understanding the biological mechanism underlying element-induced cataract may contribute to preventing cataractogenesis and providing targeted interventions.

Effects of hyaluronic acid on sperm parameters, mitochondrial function and apoptosis of spermatozoa in Simmental bulls with good and poor freezing ability

Bulls with varying freezability exhibit substantial variation in semen characteristics after cryopreservation. Sperm freezability is positively correlated with membrane cholesterol content, membrane integrity, mitochondrial activity and antioxidant content. The purpose of this study was to determine the optimal concentration of hyaluronic acid (HA) in bull sperm with different cryotolerances. Simmental bulls (n = 10) semen samples were taken and categorized based on their progressive motility (PM) after freeze-thawing: Group I, consisting of bulls (n = 5) with progressive sperm motility ≥45%, was considered good freezability ejaculates (GF), and Group II, including bulls (n = 5) with progressive sperm motility ≤30%, was considered poor freezability ejaculates (PF) bulls. Semen samples were diluted with a Tris-egg-yolk-glycerol (TEYG) extender containing various concentrations of HA: without HA (control), 1 mM HA, 2 mM HA and 4 mM HA. After the freeze-thaw process, sperm kinematics, plasma membrane and acrosome integrity, mitochondrial activity and apoptotic status were evaluated. The addition of 1 mM HA to the diluent of bulls with GF increased PM and linearity (LIN) compared to the control group (p < 0.05). Normal morphology was improved after thawing in the samples treated with 1 and 2 mM HA in the GF and PF bulls respectively. The membrane and acrosome integrity of GF bulls treated with 1 mM HA was significantly (p < 0.05) greater than that of the control groups. Adding 1 mM HA to the extender of bulls with GF and PF improved the proportion of viable cells compared with the highest concentration (4 mM) of HA. The mitochondrial activity of PF bulls treated with 1 and 2 mM HA was significantly (p < 0.05) greater than that of the controls and 4 mM HA. Finally, it can be concluded that adding low doses of HA (1 mM) to the TEYG extender of GF and PF bulls ameliorated the post-thaw semen quality.

Synergistic Effect of L-Carnosine and Hyaluronic Acid in Their Covalent Conjugates on the Antioxidant Abilities and the Mutual Defense against Enzymatic Degradation

Hyaluronic acid (Hy) is a natural linear polymer that is widely distributed in different organisms, especially in the articular cartilage and the synovial fluid. During tissue injury due to oxidative stress, Hy plays an important protective role. All the beneficial properties of Hy make the polymer attractive for many biomedical uses; however, the low stability and short biological half-life limit Hy application. To overcome these problems, the addition of small antioxidant molecules to Hy solution has been employed to protect the molecular integrity of Hy or delay its degradation. Carnosine (β-alanyl-L-histidine, Car) protects cells from the damage due to the reactive species derived from oxygen (ROS), nitrogen (RNS) or carbonyl groups (RCS). Car inhibits the degradation of hyaluronan induced by free radical processes in vitro but, like Hy, the potential protective action of Car is drastically hampered by the enzymatic hydrolysis in vivo. Recently, we conjugated Hy to Car and the derivatives (HyCar) showed protective effects in experimental models of osteoarthritis and rheumatoid arthritis in vivo. Here we report the antioxidant activity exerted by HyCar against ROS, RNS and RCS. Moreover, we tested if the covalent conjugation between Hy and Car inhibits the enzymatic hydrolysis of the polymer and the dipeptide backbone. We found that the antioxidant properties and the resistance to the enzymatic hydrolysis of Hy and Car are greatly improved by the conjugation.

In vivo MRI evaluation of early postnatal development in normal and impaired rat eyes

This study employed in vivo 7-T magnetic resonance imaging (MRI) to evaluate the postnatal ocular growth patterns under normal development or neonatal impairments in Sprague-Dawley rats. Using T2-weighted imaging on healthy rats from postnatal day (P) 1 (newborn) to P60 (adult), the volumes of the anterior chamber and posterior chamber (ACPC), lens, and vitreous humor increased logistically with ACPC expanding by 33-fold and the others by fivefold. Intravitreal potassium dichromate injection at P1, P7, and P14 led to T1-weighted signal enhancement in the developing retina by 188-289%. Upon unilateral hypoxic-ischemic encephalopathy at P7, monocular deprivation at P15, and monocular enucleation at P1, T2-weighted imaging of the adult rats showed decreased ocular volumes to different extents. In summary, in vivo high-field MRI allows for non-invasive evaluation of early postnatal development in the normal and impaired rat eyes. Chromium-enhanced MRI appeared effective in examining the developing retina before natural eyelid opening at P14 with relevance to lipid metabolism. The reduced ocular volumes upon neonatal visual impairments provided evidence to the emerging problems of why some impaired visual outcomes cannot be solely predicted by neurological assessments and suggested the need to look into both the eye and the brain under such conditions.

Formic acid motivated photocatalytic reduction of Cr(VI) to Cr(III) with ZnFe2O4 nanoparticles under UV irradiation

UV-light irradiated photocatalytic reduction of Cr(VI) to Cr(III) in aqueous solution using ZnFe₂O₄ nanoparticles in the presence of formic acid was reported. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and UV-Vis diffuse reflectance spectroscopy (DRS) were employed to characterize ZnFe₂O₄ nanoparticles. The photocatalytic activity of pure ZnFe₂O₄ under UV irradiation was significantly low. However, the Cr(VI) reduction efficiency on nano-sized ZnFe₂O₄ in the presence of 0.40% formic acid reached 95.4% within 4 h. Herein, the effect of pH, photocatalyst amount, initial concentration of Cr(VI) and formic acid concentration on the photocatalytic reduction of Cr(VI) was investigated. The results indicated that the photocatalytic reduction of Cr(VI) decreased with increase in the initial concentration of Cr(VI), photocatalyst dosage and pH. The reduction rate constant declined from 0.017 min^-1 to 0.0023 min^-1 with the increase in initial concentration of Cr(VI) from 5 to 25 mg L^-1. However, the reduction rate constant sharply increased from 0.000075 min^-1 to 0.0127 min^-1 with the increase in formic acid concentration from 0.05% to 0.40%. The formic acid could capture the photogenerated holes, and eventually formate (HCOO^-) ions could be converted into carbon dioxide radicals (•CO₂^-). Because of more negative redox potential for •CO₂^- radicals, Cr(VI) species could easily be reduced to Cr(III) under UV irradiation. The pseudo-first-order kinetic reaction was confirmed for this reduction process. A tenable mechanism for the photocatalytic Cr(VI) reduction has also been demonstrated.

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.

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.

Impact of Ergothioneine, Hercynine, and Histidine on Oxidative Degradation of Hyaluronan and Wound Healing

A high-molecular weight hyaluronan is oxidatively degraded by Cu(II) ions and ascorbate—the so called Weissberger biogenic oxidative system—which is one of the most potent generators of reactive oxygen species, namely ^•OH radicals. Ergothioneine, hercynine, or histidine were loaded into chitosan/hyaluronan composite membranes to examine their effect on skin wound healing in ischemic rabbits. We also explored the ability of ergothioneine, hercynine, or histidine to inhibit hyaluronan degradation. Rotational viscometry showed that ergothioneine decreased the degree of hyaluronan radical degradation in a dose-dependent manner. While histidine was shown to be potent in scavenging ^•OH radicals, however, hercynine was ineffective. In vivo results showed that the addition of each investigated agent to chitosan/hyaluronan membranes contributed to a more potent treatment of ischemic skin wounds in rabbits compared to untreated animals and animals treated only with chitosan/hyaluronan membranes.

Esculetin protects human corneal epithelial cells from oxidative stress through Nrf-2 signaling pathway

Dry eye formation often originates from oxidative damage to the ocular surface, which can be caused by external environment or internal pathologic factors. Esculetin (6, 7-dihydroxycoumarin) is a natural product found in many plants, and has been reported to have multiple pharmacological activities. The objective of our present study is to investigate if esculetin could protect the corneal epithelial cells from oxidative damages and its underlying antioxidant molecular mechanisms. Our experimental results demonstrated that pretreatment with esculetin markedly increased the cell viability while decreased the apoptosis in H₂O₂-treated human corneal epithelial (HCE) cells, by regulating Bcl-2, Bax and caspase-3 protein expressions and by altering the imbalance of activities of intracellular reactive oxygen species (ROS) and superoxide dismutase (SOD). Our data revealed that esculetin played an antioxidant role not only through its antioxidant activity, but also by highly inducing Nrf-2 translocation to the nucleus, which in turn, enhanced Nrf2 signaling regulated antioxidant genes (HO-1, NQO1, GCLM, SOD1 and SOD2) mRNA expression levels in H₂O₂-treated HCE cells. In the present study, the protective effects of esculetin on the corneal epithelium were also confirmed by a murine desiccating stress induced dry eye model in vivo. These data illustrated, for the first time, that esculetin may have the ability to protect human corneal epithelial cells from oxidative damages through its scavenging of free radical properties and through the activation of Nrf2 signaling.

Naked mole-rat very-high-molecular-mass hyaluronan exhibits superior cytoprotective properties

Naked mole-rat (NMR), the longest-living rodent, produces very-high-molecular-mass hyaluronan (vHMM-HA), compared to other mammalian species. However, it is unclear if exceptional polymer length of vHMM-HA is important for longevity. Here, we show that vHMM-HA (>6.1 MDa) has superior cytoprotective properties compared to the shorter HMM-HA. It protects not only NMR cells, but also mouse and human cells from stress-induced cell-cycle arrest and cell death in a polymer length-dependent manner. The cytoprotective effect is dependent on the major HA-receptor, CD44. We find that vHMM-HA suppresses CD44 protein-protein interactions, whereas HMM-HA promotes them. As a result, vHMM-HA and HMM-HA induce opposing effects on the expression of CD44-dependent genes, which are associated with the p53 pathway. Concomitantly, vHMM-HA partially attenuates p53 and protects cells from stress in a p53-dependent manner. Our results implicate vHMM-HA in anti-aging mechanisms and suggest the potential applications of vHMM-HA for enhancing cellular stress resistance.

Mitochondrial Dysfunctions May Be One of the Major Causative Factors Underlying Detrimental Effects of Benzalkonium Chloride

Benzalkonium chloride (BAC) is currently the most commonly used antimicrobial preservative in ophthalmic solutions, nasal sprays, and cosmetics. However, a large number of clinical and experimental investigations showed that the topical administration of BAC-containing eye drops could cause a variety of ocular surface changes, from ocular discomfort to potential risk for future glaucoma surgery. BAC-containing albuterol may increase the risk of albuterol-related systemic adverse effects. BAC, commonly present in personal care products, in cosmetic products can induce irritation and dose-dependent changes in the cell morphology. The cationic nature of BAC (it is a quaternary ammonium) suggests that one of the major targets of BAC in the cell may be mitochondria, the only intracellular compartment charged negatively. However, the influence of BAC on mitochondria has not been clearly understood. Here, the effects of BAC on energy parameters of rat liver mitochondria as well as on yeast cells were examined. BAC, being a "weaker" uncoupler, potently inhibited respiration in state 3, diminished the mitochondrial membrane potential, caused opening of the Ca2+/Pi-dependent pore, blocked ATP synthesis, and promoted H₂O₂ production by mitochondria. BAC triggered oxidative stress and mitochondrial fragmentation in yeast cells. BAC-induced oxidative stress in mitochondria and yeast cells was almost totally prevented by the mitochondria-targeted antioxidant SkQ1; the protective effect of SkQ1 on mitochondrial fragmentation was only partial. Collectively, these data showed that BAC acts adversely on cell bioenergetics (especially on ATP synthesis) and mitochondrial dynamics and that its prooxidant effect can be partially prevented by the mitochondria-targeted antioxidant SkQ1.

Inhibition of NIPBL enhances the chemosensitivity of non-small-cell lung cancer cells via the DNA damage response and autophagy pathway

Background

Previously, we reported that high expression of nipped-B-like protein (NIPBL) was strongly correlated with poor prognosis, tumor differentiation, and lymph node metastasis. Survival analysis indicated that NIPBL expression was a potential prognostic factor for non-small cell lung cancer (NSCLC). Moreover, loss of NIPBL decreased lung cancer cells proliferation, migration, invasion and promoted apoptosis as well as sensitivity to chemotherapeutic agents. However, the deep mechanisms were not explored.

Purpose

The objective of this study was to identify the role of NIPBL in DNA damage response, as well as autophagy pathway, so as to interpret the mechanisms of how NIPBL knockdown enhances the chemosensitivity of lung cancer cell.

Methods

Cells (NCI-H1299 and NCI-H1650) were transfected by specific siRNAs before immunofluorescence and single-cell gel electrophoresis, which were mainly used to observe the differences of DNA damage in different groups. Additionally, protein were obtained and then analyzed by western blot and mass spectroscopy.

Results

In this study, we found that knockdown of NIPBL resulted in accumulation of phosphorylated H2AX (γ-H2AX) foci and higher levels of DNA damage, as revealed by comet assay. Western blot assay revealed that loss of NIPBL decreased expression of ATM/ATR, Rad3-related protein and Ku70/Ku80, but increased expression of LC3-B and depletion of p62. Using mass spectroscopy, we identified eight proteins that were significantly differentially expressed upon NIPBL knockdown. Gene Ontology analysis revealed that these proteins are mainly involved in DNA repair, mismatch repair, and binding to damaged DNA. The expression changes in two of the proteins, MSH2 and STAT1, were verified by Western blotting in NIPBL-knockdown cells.

Conclusions

In summary, these results reflected that loss of NIPBL impairs the DNA damage response and promotes autophagy. And NIPBL suppression may represent a novel strategy for preventing chemotherapy resistance in lung cancer.