Lipopolysaccharide Enhances Genotoxicity by Activating GADD45G and NF-κB in Human Corneal Epithelial Cells

As the prevalence of microbial keratitis increases, it creates an environment conducive to genotoxicity response. A potential connection between growth arrest and DNA-damage-inducible 45 gamma (GADD45G) gene expression has not been proven in the corneal epithelial cells. The aim of this study was to determine whether lipopolysaccharide (LPS) enhances genotoxicity, DNA damage, and inflammatory responses in human corneal epithelial cells (HCECs) in vitro. In a set of parameters, cytotoxicity, reactive oxygen species, mitochondrial membrane potential, DNA damage, inflammatory response, and apoptosis were assessed. LPS (1, 5, and 10 μg/mL) treated HCECs were increased reactive oxygen species formation, mitochondrial membrane depolarization, and genotoxicity in a concentration-dependent manner. Similarly, NF-κB, PARP1, and TP53 were also overexpressed in the LPS treated HCECs. 24 hours after LPS induction, micronucleus scoring, and proapoptotic factors were also increased. Among them, the GADD45G, NF-κB, and γH2AX were overexpressed both on the mRNA and protein levels in LPS (10 μg/mL) treated HCECs. In our study, we show that the GADD45G signaling can trigger genotoxic instability in HCECs exposed to LPS. Therefore, understanding the factors contributing to infectious keratitis, such as GADD45G, NF-κB, and γH2AX signaling, may help to develop antigenotoxic and anti-inflammatory therapies for corneal dystrophy and epithelial cell remodeling.

Inhibitory Effect of Ursolic Acid on Ultraviolet B Radiation-Induced Oxidative Stress and Proinflammatory Response-Mediated Senescence in Human Skin Dermal Fibroblasts

Ultraviolet radiation is an environmental carcinogenic agent that enhances inflammation and immunological reactions in the exposed human skin cells leading to oxidative photoaging of the epidermal and dermal segment. In the present study, we investigated the protective role of ursolic acid (UA) against ultraviolet B (UVB) radiation- induced photoaging an in vitro model of human skin dermal fibroblasts. UA-pretreated human skin dermal fibroblast (HDF) cells were exposed to UVB radiation to evaluated cell viability, reactive oxygen species (ROS), mitochondrial membrane potential, lipid peroxidation, antioxidant status, DNA damage, proinflammatory response, apoptotic induction, and matrix metalloproteinase (MMP) alteration. The UA pretreatment of HDFs mitigated the UVB irradiation-induced cytotoxicity, ROS generation, and mitochondrial membrane potential alteration and lipid peroxidation, depletion of antioxidant status, DNA damage, and apoptotic induction. UA pretreatment of HDFs also attenuated the UVB-induced expression of inflammatory (TNF-α and NF-κB) and apoptotic (p53, Bax, and caspase-3) and MMPs (MMP-2 and MMP-9) and enhanced the Bcl-2 protein levels in 20 μM UA treatment, when compared to concentrations. Hence, these results revealed that UA has the potential to mitigate UVB-induced extracellular damage by interfering with the ROS-mediated apoptotic induction and photoaging senescence and thus is a potential therapeutic agent to protect the skin against UVB-irradiation induced photooxidative damage.

Geraniol Protects Against the Protein and Oxidative Stress Induced by Rotenone in an In Vitro Model of Parkinson's Disease

Dysfunction of autophagy, mitochondrial dynamics and endoplasmic reticulum (ER) stress are currently considered as major contributing factors in the pathogenesis of Parkinson's disease (PD). Accumulation of oxidatively damaged cytoplasmic organelles and unfolded proteins in the lumen of the ER causes ER stress and it is associated with dopaminergic cell death in PD. Rotenone is a pesticide that selectively kills dopaminergic neurons by a variety of mechanism, has been implicated in PD. Geraniol (GE; 3,7-dimethylocta-trans-2,6-dien-1-ol) is an acyclic monoterpene alcohol occurring in the essential oils of several aromatic plants. In this study, we investigated the protective effect of GE on rotenone-induced mitochondrial dysfunction dependent oxidative stress leads to cell death in SK-N-SH cells. In addition, we assessed the involvement of GE on rotenone-induced dysfunction in autophagy machinery via α-synuclein accumulation induced ER stress. We found that pre-treatment of GE enhanced cell viability, ameliorated intracellular redox, preserved mitochondrial membrane potential and improves the level of mitochondrial complex-1 in rotenone treated SK-N-SH cells. Furthermore, GE diminishes autophagy flux by reduced autophagy markers, and decreases ER stress by reducing α-synuclein expression in SK-N-SH cells. Our results demonstrate that GE possess its neuroprotective effect via reduced rotenone-induced oxidative stress by enhanced antioxidant status and maintain mitochondrial function. Furthermore, GE reduced ER stress and improved autophagy flux in the neuroblastomal SK-N-SH cells. The present study could suggest that GE a novel therapeutic avenue for clinical intervention in neurodegenerative diseases especially for PD.

EUK-207 protects human intestinal microvascular endothelial cells (HIMEC) against irradiation-induced apoptosis through the Bcl2 pathway

AIM

To elucidate the signaling mechanisms involved in the protective effect of EUK-207 against irradiation-induced cellular damage and apoptosis in human intestinal microvasculature endothelial cells (HIMEC).

METHODS

HIMECs were irradiated and treated with EUK-207. Using hydroethidine and DCF-DA fluorescent probe the intracellular superoxide and reactive oxygen species (ROS) were determined. By real-time PCR and western blotting caspase-3, Bcl2 and Bax genes and proteins were analyzed. Proliferation was determined by [(3)H]-thymidine uptake. Immunofluorescence staining was used for translocation of p65 NFκB subunit.

KEY FINDING

Irradiation increased ROS production, apoptosis, Bax, Caspase3 and NFkB activity in HIMEC and inhibited cell survival/growth/proliferation. EUK-207 restored the endothelial functions, markedly inhibited the ROS, up-regulated the Bcl2 and down-regulated Bax and prevented NFκB caspase 3 activity in HIMEC.

SIGNIFICANCE

HIMEC provide a novel model to define the effect of irradiation induced endothelial dysfunction. Our findings suggest that EUK-207 effectively inhibits the damaging effect of irradiation.

Novel synthetic SOD/catalase mimetics can mitigate capillary endothelial cell apoptosis caused by ionizing radiation

Numerous in vitro and in vivo studies have shown that the endothelial cells of the microvasculature of the lung and kidney are damaged by exposure to ionizing radiation, and this sustained endothelial cell injury is involved in the early and late radiation effects observed in these tissues. It is well accepted that ionizing radiation causes the generation of reactive oxygen species during exposure that results in damage to DNA and cellular organelles. It is more controversial, however, whether additional biochemical events or long-lived radicals occur and persist postirradiation that amplify and initiate new forms of cellular damage. Two families of Eukarion (EUK) compounds have been synthesized that possess superoxide dismutase (SOD), catalase and peroxidase activities. The Mn porphyrins are available orally whereas the salen Mn complexes are administered by injection. In the present study we have examined the ability of these SOD/catalase mimetics to prevent apoptosis of endothelial cells when administered 1 h postirradiation (mitigation). A range of salen Mn complex (EUK-189 and EUK-207) and Mn porphyrins (EUK-418, -423, -425, -450, -451, -452, -453) were used to treat endothelial cells 1 h after the cells received 2-20 Gy ionizing radiation in vitro. Two lead compounds, EUK-207 at a dose of 30 microM and EUK-451 at a dose of 10 microM, exhibited low toxicity and mitigated radiation-induced apoptosis. Future animal studies will test whether these compounds protect when administered after radiation exposure as would be done after a radiological accident or a terrorism event.

Increased mitochondrial superoxide dismutase expression and lowered production of reactive oxygen species during rotavirus infection

Rotaviruses are responsible for severe diarrhea in infants and substantial economic losses in animal husbandry worldwide. We investigated the oxidant/antioxidant status in rotavirus-infected human colon adenocarcinoma (Caco-2) cell line. Our results show that within the initial 48 h of infection the expression of the mitochondrial superoxide dismutase (MnSOD) is significantly increased, which correlates with a decrease in reactive oxygen species production, and with a lack of cellular glutathione depletion. During this period the mitochondria display a hyperpolarization of the inner membrane, which leads to an increased mitochondrial membrane potential. No increase in apoptosis was detected in the infected cultures. In contrast to many viral infections which cause redox imbalance in host cells, the described virus-host interaction suggests that rotavirus infection does not lead to an induction of oxidative stress, possibly to prolong cell survival and to allow for accumulation of viral particles before cell destruction and virus release.