Antioxidant N-acetyl-cysteine increasing cell adhesion capability could facilitate the biocompatibility processes

Riboflavin Surface Modification of Poly(vinyl chloride) for Light-Triggered Control of Bacterial Biofilm and Virus Inactivation

Poly(vinyl chloride) (PVC) is the most used biomedical polymer worldwide. PVC is a stable and chemically inert polymer. However, microorganisms can colonize PVC producing biomedical device-associated infections. While surface modifications of PVC can help improve the antimicrobial and antiviral properties, the chemically inert nature of PVC makes those modifications challenging and potentially toxic. In this work, we modified the PVC surface using a derivative riboflavin molecule that was chemically tethered to a plasma-treated PVC surface. Upon a low dosage of blue light, the riboflavin tethered to the PVC surface became photochemically activated, allowing for Pseudomonas aeruginosa bacterial biofilm and lentiviral in situ eradication.

Free Radical Damage in Facsimile Synovium: Correlation with Adhesion Formation in Osteoarthritic TMJs

PURPOSE

The purpose of this study was to use the rat air pouch model of facsimile synovium to evaluate oxidative stress as a primary mechanism in the pathogenesis of degenerative temporomandibular joint (TMJ) disease.

MATERIALS AND METHODS

Forty-nine Sprague-Dawley adult female rats were used to generate the standard rat air pouch model of facsimile synovium. This was accomplished by daily air injections (20 cc) subdermally through the dorsal skin. Hydrogen peroxide and ferrous iron (components of the Fenton reaction which generate free radicals) were introduced into the pouches of the 4-, 7-, and 14-day groups to generate oxidative stress. Control rats were injected with phosphate-buffered solution (PBS), pH 7.4. Either N-acetylcysteine (NAC), a powerful free radical scavenger, or ibuprofen were simultaneously injected with the Fenton reagents into the pouches of the 14-day treatment groups to modulate free radical-mediated protein damage to the synovium. Animals were euthanized at appropriate experimental intervals and biopsies obtained from specimens to analyze: (1) proteins' amino acid modification (carbonyl group formation), (2) protein hydrophobicity, (3) detection of low molecular weight protein degradation products, and (4) histological and gross anatomical observations.

RESULTS

Free radicals introduced into the rat air pouch interacted with synovial tissues causing oxidation and breakdown of proteins. Clinical evidence of adhesion formation consistent with features found in osteoarthritis of the TMJ developed. The groups subjected to oxidative stress experienced statistically significant (p < 0.05) increases in carbonyl formation, carbonyls/protein, and low molecular weight protein fragments. These groups also showed significant (p < 0.05) hydrophobicity changes consistent with free radical attack. Control synovial tissues were statistically undamaged. The 14-day NAC and ibuprofen treatment groups experienced statistically significant (p < 0.05) decreases in total carbonyl formation, carbonyls/protein, and hydrophobicity. Histological and gross observations in free radical damaged synovium exhibited features consistent with known arthoscopic and arthrocentesis findings in diseased TMJs.

CONCLUSIONS

This study suggests that the rat air pouch model of facsimile synovium develops clinical evidence of adhesions and biochemical signs of protein modification when subjected to free radical attack. NAC and ibuprofen prevented carbonyl formation as well as hydrophobicity changes indicative of oxidative stress damage in facsimile synovium. These findings are consistent with features of degenerative human TMJ disease. Future direction may be taken from this study to postulate new analysis techniques and treatment modalities for patients with degenerative TMJ disease.

Influence of thiol balance on micellar cholesterol handling by polarized Caco-2 intestinal cells

The in vitro thiol redox modulation of cholesterol homeostasis was investigated in polarized Caco-2 intestinal cells. Cells were pre-incubated with the pro-oxidant compound CuSO4 or with the antioxidant N-acetylcysteine (NAC), to induce a mild shift of the intracellular redox potential toward, respectively, a more oxidizing or a more reducing equilibrium, via a manipulation of intracellular soluble thiols (glutathione). Then, monolayers were exposed to micellar cholesterol and both the cholesterol uptake and export, as well as the cholesteryl ester cycle, were analyzed. We found that pro-oxidizing conditions induced a significant cholesterol retention within the cells, particularly in the unesterified form (FC), as a result of an augmented sterol incorporation coupled with a reduced rate of FC esterification. A reduction in FC export was also evident. Furthermore, the combination of FC retention and the oxidative imbalance leads to significant alterations of the monolayer integrity, evidenced by both the enhanced tight junction permeability and the lactate dehydrogenase release into the basolateral medium. In contrast, a more reducing environment generated by NAC pre-treatment favors the limitation of the resident time of FC into the cells, via a reduced cholesterol uptake and a concomitant increased cholesterol esterification. In addition, a significant higher FC extrusion into the basolateral medium was also appreciable. Our results indicate that the thiol balance of intestinal cells may be critical for the regulation of cholesterol homeostasis at the intestinal level, influencing the lipid transport throughout the intestinal barrier.

Tyrosol, the major olive oil biophenol, protects against oxidized-LDL-induced injury in Caco-2 cells

Experimental and clinical evidence suggest that oxidative stress causes cellular damage, leading to functional alterations of the tissue. Free radicals may thus play an important role in the pathogenesis of a number of human diseases. Among pro-oxidant agents, oxidized LDL lead to the production of cytotoxic reactive species, e.g., lipoperoxides, causing tissue injury and various subsequent pathologies including intestinal diseases. Thus, to analyze the oxidative damage induced by oxidized LDL to intestinal mucosa, we evaluated morphological and functional changes induced in the human colon adenocarcinoma cell line, Caco-2. In addition, we examined the protective effects exerted by tyrosol, 2-(4-hydroxyphenyl)ethanol, the major phenolic compound present in olive oil. Caco-2 cell treatment (24 and/or 48 h) with oxidized LDL (0.2 g/L) resulted in cytostatic and cytotoxic effects characterized by a series of morphological and functional alterations: membrane damage, modifications of cytoskeleton network, microtubular disorganization, loss of cell-cell and cell-substrate contacts, cell detachment and cell death. The oxidized LDL-induced alterations in Caco-2 cells were almost completely prevented by tyrosol which was added 2 h before and present during the treatments. Our results suggest that some biophenols, such as those contained in olive oil, may counteract the reactive oxygen metabolite-mediated cellular damage and related diseases, by improving in vivo antioxidant defenses.

Antiproliferative activity of interferon alpha and retinoic acid in SiHa carcinoma cells: the role of cell adhesion

Several lines of evidence have demonstrated that IFNs could be relevant in the treatment of certain neoplastic diseases such as carcinomas. In particular, IFN-alpha, in addition to the anti-proliferative and cytostatic effects, was demonstrated to be capable of inducing cell death by apoptosis both in vivo and in vitro. Numerous protocols have also been proposed which consider the association of IFN-alpha with other drugs. Among these are retinoids, a class of compounds capable of inducing inhibition of cell growth and differentiation. We address the question here by analyzing the role of cell adhesion in susceptibility to IFN-alpha, RA and their combination of a human cell line derived from a squamous carcinoma of the cervix, the Bcl-2-negative SiHa cell line. In this context, cytoskeleton components and several surface molecules playing a role in cell substrate and cell-to-cell relationships have been evaluated. We found that RA treatment is capable of improving stress fiber formation, decreasing cell detachment and increasing cell-adhesion capability. However, no variations in the ability to adhere to specific extracellular-matrix molecules were found in RA-treated cells. No quantitative changes were detected in integrins involved as receptors for extracellular matrix molecules (VLAI-VLA5) or in other cell-adhesion-associated molecules (e.g., CD44). By contrast, 2 important molecules involved in cell-adhesion processes appeared to be up-regulated by RA exposure: focal adhesion kinase and E-cadherin, involved in adhesion plaque formation and cell-to-cell contacts, respectively. Keeping in mind the importance of adhesion properties in the cell-growth pathway, our findings could be of interest in the study of carcinoma-cell proliferation and metastatic potential.

The highly reducing sugar 2-deoxy-D-ribose induces apoptosis in human fibroblasts by reduced glutathione depletion and cytoskeletal disruption

2-deoxy-D-Ribose (dRib), the most reducing sugar, induces apoptosis in normal human fibroblasts, as judged by cytoplasmic shrinkage, chromatin condensation, DNA fragmentation and mitochondrial depolarization. This effect is independent from culture conditions, such as cell density and the presence or absence of serum in the culture milieu, suggesting that dRib-induced apoptosis is cell cycle-independent. dRib was found also to provoke disruption of the actin filament network and detachment from the substratum, while at the same time, interestingly, it increases the expression of several integrins and cell adhesion molecules. Furthermore, dRib was found to reduce the intracellular levels of reduced glutathione (GSH). The apoptotic process was not affected by the macromolecular-synthesis inhibitors cycloheximide and actinomycin D. On the contrary, the antioxidant N-acetyl-L-cysteine (NAC) fully blocks the dRib-induced apoptosis by preventing GSH depletion, while it also inhibits actin-filament-network disruption and mitochondrial depolarization. The above indicate that dRib induces apoptosis in human fibroblasts by a mechanism involving glutathione metabolism and oxidative stress, as well as disturbance of cytoskeletal integrity and cell adhesion.