Reactive oxidant species and oxidation of protein and heamoglobin as biomarkers of susceptibility to stress caused by chloramphenicol

Hydrochlorothiazide Use and Risk of Nonmelanoma Skin Cancers: A Biological Plausibility Study

Recent studies reported the association between increased risk of nonmelanoma skin cancers (NMSCs) and the use of hydrochlorothiazide (HCTZ), one of the most commonly prescribed diuretic, antihypertensive drug, over the world. Although HCTZ is known to be photosensitizing, the mechanisms involved in its potential prophotocarcinogenic effects remain unclear. Under acute exposure, therapeutically relevant concentrations of HCTZ (70, 140, and 370 ng/mL) amplified UVA-induced double-strand breaks, oxidative DNA, and protein damage in HaCaT human keratinocytes, and this effect was associated to a defective activity of the DNA repair enzyme, OGG1. Oxidative damage to DNA, but not that to proteins, was reversible within few hours. After chronic, combined exposure to HCTZ (70 ng/mL) and UVA (10 J/cm2), for 9 weeks, keratinocytes acquired a dysplastic-like phenotype characterized by a multilayered morphology and alterations in cell size, shape, and contacts. At the ultrastructural level, several atypical and enlarged nuclei and evident nucleoli were also observed. These transformed keratinocytes were apoptosis resistant, exhibited enhanced clonogenicity capacity, increased DNA damage and inflammation, defective DNA repair ability, and increased expression of the oncogene ΔNp63α and intranuclear β-catenin accumulation (a hallmark of Wnt pathway activation), compared to those treated with UVA alone. None of these molecular, morphological, or functional effects were observed in cells treated with HCTZ alone. All these features resemble in part those of preneoplastic lesions and NMSCs and provide evidence of a biological plausibility for the association among exposure to UVA, use of HCTZ, and increased risk of NMSCs. These results are of translational relevance since we used environmentally relevant UVA doses and tested HCTZ at concentrations that reflect the plasma levels of doses used in clinical practice. This study also highlights that drug safety data should be followed by experimental evaluations to clarify the mechanistic aspects of adverse events.

Effect of Dipeptidyl-Peptidase 4 Inhibitors on Circulating Oxidative Stress Biomarkers in Patients with Type 2 Diabetes Mellitus

Pre-clinical studies suggested potential cardiovascular benefits of dipeptidyl peptidase-4 inhibitors (DPP4i), however, clinical trials showed neither beneficial nor detrimental effects in patients with type 2 diabetes mellitus (T2DM). We examined the effects of DPP4i on several circulating oxidative stress markers in a cohort of 32 T2DM patients (21 males and 11 post-menopausal females), who were already on routine antidiabetic treatment. Propensity score matching was used to adjust demographic and clinical characteristics between patients who received and who did not receive DPP4i. Whole-blood reactive oxygen species (ROS), plasma advanced glycation end products (AGEs), advanced oxidation protein products (AOPP), carbonyl residues, as well as ferric reducing ability of plasma (FRAP) and leukocyte DNA oxidative damage (Fpg sites), were evaluated. With the exception of Fpg sites, that showed a borderline increase in DPP4i users compared to non-users (p = 0.0507), none of the biomarkers measured was affected by DPP4i treatment. An inverse correlation between estimated glomerular filtration rate and AGEs (p < 0.0001) and Fpg sites (p < 0.05) was also observed. This study does not show any major effect of DPP4i on oxidative stress, assessed by several circulating biomarkers of oxidative damage, in propensity score-matched cohorts of T2DM patients.

Analysis of Oxidative Stress-Related Markers in Crohn's Disease Patients at Surgery and Correlations with Clinical Findings

Crohn' disease (CD) patients are at high risk of postoperative recurrence and new tools for the assessment of disease activity are needed to prevent long-term complications. In these patients, the over-production of ROS generated by inflamed bowel tissue and inflammatory cells activates a pathogenic cascade that further exacerbates inflammation and leads to increased oxidative damage to DNA, proteins, and lipids. We measured the products of protein/lipid oxidation and the total antioxidant capacity (ferric reducing ability of plasma, FRAP) in the serum of CD patients with severe disease activity requiring surgery with the aim to characterize their redox status and identify associations between oxidative stress-related markers and their clinical characteristics. At the systemic level, CD was associated with increased levels of protein and lipid oxidation products when compared to healthy volunteers, even though the FRAP values were similar. Advanced oxidation protein product (AOPP) levels showed the highest difference between patients and the controls (11.25, 5.02-15.15, vs. 1.36, 0.75-2.70, median, interquartile range; p < 0.0001) and the analysis of receiver operating characteristic (ROC) curves, indicated for AOPP, the best area under the curve (AUC) value for CD prediction. Advanced glycated end-products (AGEs) were also significantly higher in CD patients (p < 0.01), which is of interest since AOPP and AGEs are both able to activate the membrane receptor for advanced glycation end products (RAGE) involved in inflammatory diseases. Thiobarbituric acid reactive substance (TBARS) levels were significantly higher in CD patients with ileal localization and aggressive disease behavior, in smokers, and in patients suffering from allergies. In conclusion, our data indicate that circulating oxidative stress biomarkers may be attractive candidates as disease predictors as well as for clinical or therapeutic monitoring of CD. Our results also suggest that AOPP/AGEs and RAGE signaling may represent a pathogenic factor and a potential therapeutic target in CD.

Aging related changes in circulating reactive oxygen species (ROS) and protein carbonyls are indicative of liver oxidative injury

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Circulating ROS and protein carbonyls increase as early as middle age.

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Oxidative DNA damage is increased in the liver of middle age rats.

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DNA damage repairing capacity is reduced in the liver of middle age rats.

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Circulating protein carbonyls are indicative of oxidative liver injury.

Oxidative stress, defined as an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense mechanisms, plays a major role in inducing oxidative damage and cellular impairment, resulting in a general decline of the physiological functions. The aim of this work was to evaluate age-related changes in circulating ROS levels and plasma protein carbonyls, in very young (2 months aged), young (8 months aged) and in middle age (15 months aged) F344 rats. In addition, the DNA oxidative marker 8-hydroxy-2′-deoxyguanosine (8-OHdG) and the expression of the DNA repair enzymes APE1, OGG1 and UNG genes were also measured in the liver of these animals. We also determined whether systemic oxidative stress reflects oxidative injury at organ level. Our results demonstrate that the increase in circulating ROS and protein carbonyl content occurs as early as middle age. Moreover, increased 8-OHdG in the liver of 15-month-old rats was at least in part associated with a reduced DNA damage repairing capacity as suggested by the down-regulation of APE1 gene expression. In addition, we demonstrated for the first time, that plasma carbonyls and liver 8-OHdG are well correlated, suggesting that plasma protein carbonyls may be used as a surrogate marker of oxidative injury in target organs.

Pharmacological activities of an eye drop containing Matricaria chamomilla and Euphrasia officinalis extracts in UVB-induced oxidative stress and inflammation of human corneal cells

Ultraviolet B (UVB) exposure is a risk factor for corneal damage resulting in oxidative stress, inflammation and cell death. The aim of this study was to investigate the potential protective effects of a commercial eye drop (Dacriovis™) containing Matricaria chamomilla and Euphrasia officinalis extracts on human corneal epithelial cells (HCEC-12) against UVB radiation-induced oxidative stress and inflammation as well as the underlying mechanisms. The antioxidant potential of the eye drops was evaluated by measuring the ferric reducing antioxidant power and the total phenolic content by Folin-Ciocalteu reagent. HCEC-12 cells were exposed to UVB radiation and treated with the eye drops at various concentrations. Cell viability, wound healing assay, reactive oxygen species (ROS) levels, protein and lipid oxidative damage and COX-2, IL-1β, iNOS, SOD-2, HO-1 and GSS gene expression, were assessed. Eye drops were able to protect corneal epithelial cells from UVB-induced cell death and ameliorated the wound healing; the eye drops exhibited a strong antioxidant activity, decreasing ROS levels and protein and lipid oxidative damage. Eye drops also exerted anti-inflammatory activities by decreasing COX-2, IL-1β, iNOS expression, counteracted UVB-induced GSS and SOD-2 expression and restored HO-1 expression to control levels. These findings suggest that an eye drop containing Matricaria chamomilla and Euphrasia officinalis extracts exerts positive effects against UVB induced oxidative stress and inflammation and may be useful in protecting corneal epithelial cells from UVB exposure.

E-cigarettes induce toxicological effects that can raise the cancer risk

Electronic cigarettes (e-cigs) are devices designed to deliver nicotine in a vaping solution rather than smoke and without tobacco combustion. Perceived as a safer alternative to conventional cigarettes, e-cigs are aggressively marketed as lifestyle-choice consumables, thanks to few restrictions and a lack of regulatory guidelines. E-cigs have also gained popularity among never-smokers and teenagers, becoming an emergent public health issue. Despite the burgeoning worldwide consumption of e-cigs, their safety remains largely unproven and it is unknown whether these devices cause in vivo toxicological effects that could contribute to cancer. Here we demonstrate the co-mutagenic and cancer-initiating effects of e-cig vapour in a rat lung model. We found that e-cigs have a powerful booster effect on phase-I carcinogen-bioactivating enzymes, including activators of polycyclic aromatic hydrocarbons (PAHs), and increase oxygen free radical production and DNA oxidation to 8-hydroxy-2'-deoxyguanosine. Furthermore, we found that e-cigs damage DNA not only at chromosomal level in peripheral blood, such as strand breaks in leucocytes and micronuclei formation in reticulocytes, but also at gene level such as point mutations in urine. Our results demonstrate that exposure to e-cigs could endanger human health, particularly among younger more vulnerable consumers.

Protective effect of quercetin in gentamicin-induced oxidative stress in vitro and in vivo in blood cells. Effect on gentamicin antimicrobial activity

We have evaluated the effect of gentamicin and gentamicin plus quercetin on ROS production, endogenous antioxidant defenses (SOD and CAT) and lipid peroxidation in vitro on human leukocytes and in vivo on whole rat blood. Gentamicin generated ROS production in human leukocytes, produced a dual effect on both enzymes dosage-dependent and generated an increase in lipid peroxidation. Quercetin, in leukocytes stimulated by gentamicin, showed more inhibitory capacity in ROS production than the reference inhibitor (vitaminC) in mononuclear cells and a similar protective behavior at this inhibitor in polymorphonuclear cells. Quercetin, in both cellular systems, tend to level SOD and CAT activities, reaching basal values and could prevent lipidic peroxidation induced by gentamicin. The results in Wistar rats confirmed that therapeutic doses of gentamicin can induce oxidative stress in whole blood and that the gentamicin treatment plus quercetin can suppress ROS generation, collaborate with SOD and CAT and diminish lipid peroxidation. Finally, flavonoid and antibiotic association was evaluated on the antimicrobial activity in S. aureus and E. coli, showing that changes were not generated in the antibacterial activity of gentamicin against E. coli strains, while for strains of S. aureus a beneficial effect observes. Therefore, we have demonstrated that gentamicin could induce oxidative stress in human leukocytes and in whole blood of Wistar rats at therapeutic doses and that quercetin may to produce a protective effect on this oxidative stress generated without substantially modifying the antibacterial activity of gentamicin against E. coli strains, and it contributes to this activity against S. aureus strains.

Monoamine Oxidase Is Overactivated in Left and Right Ventricles from Ischemic Hearts: An Intriguing Therapeutic Target

Growing evidence indicates that reactive oxygen species (ROS) may play a key role in human heart failure (HF). Monoamine oxidase (MAO) is emerging as a major ROS source in several cardiomyopathies. However, little is known about MAO activity in human failing heart and its relationship with redox imbalance. Therefore, we measured MAO activity in the left (LV) and in the right (RV) ventricle of human nonfailing (NF) and in end-stage ischemic (IHD) and nonischemic failing hearts. We found that both MAO isoforms (MAO-A/B) significantly increased in terms of activity and expression levels only in IHD ventricles. Catalase and aldehyde dehydrogenase-2 activities (ALDH-2), both implicated in MAO-catalyzed catecholamine catabolism, were significantly elevated in the failing LV, whereas, in the RV, statistical significance was observed only for ALDH-2. Oxidative stress markers levels were significantly increased only in the failing RV. Actin oxidation was significantly elevated in both failing ventricles and related to MAO-A activity and to functional parameters. These data suggest a close association between MAO-A-dependent ROS generation, actin oxidation, and ventricular dysfunction. This latter finding points to a possible pathogenic role of MAO-A in human myocardial failure supporting the idea that MAO-A could be a new therapeutic target in HF.

Gender-related drug effect on several markers of oxidation stress in diabetes patients with and without complications

We previously reported that circulating lipid (malondialdehyde, MDA) and protein oxidation (carbonyl residues, CO) products can be used as markers of risk for complications in poorly controlled type 2 diabetics. Now, we aimed to evaluate the existence of a gender effect on classical disease markers and oxidative stress parameters and on the effectiveness of metformin and/or statins in reducing CV risk in poorly controlled type 2 diabetics with and without complications. Our results show that diabetics with complications had higher plasma levels of FRAP, SOD and hs-CRP than those without complications, with FRAP and SOD found increased in both genders. Interestingly, male and female patients with complications had higher plasma levels of hs-CRP and MDA respectively, over patients without complications. Multivariate analysis indicated metformin and statin treatments effective in reducing plasma hs-CRP only in female and not in male diabetics with complications. In these latter females, a positive correlation between hs-CRP and triglycerides (TG) levels was found suggesting a causal relationship between them. Statin treatment was effective in reducing MDA in diabetics with complications irrespective of the gender. These data support the addition of statins to diabetic standard therapy to control oxidation injury and inflammation and, for the first time, indicate female patients with complications more responsive than males to the CV protection offered by metformin.

Inhibition of cytotoxicity of Shiga toxin of Escherichia coli O157:H7 on vero cells by Prosopis alba Griseb (Fabaceae) and Ziziphus mistol Griseb (Rhamnaceae) extracts

The capacity of Prosopis alba Griseb. and Ziziphus mistol Griseb. fruit extracts to inhibit the toxic action of Shiga toxin (Stx) was investigated. Purification of Stx from Escherichia coli O157:H7 was performed by saline precipitation and affinity chromatography using a column with globotriaosylceramide, while the fruits were subjected to ethanolic or aqueous extractions. The protective action of both fruits was determined by pre-, co-, and postincubation of one 50% cytotoxic dose per ml of Stx with different concentrations of ethanolic and aqueous extracts in confluent monolayers of Vero cells for 72 h at 37°C (5% CO2). The inhibition of the cytotoxic effect of Stx by fruit extracts was determined by the neutral red vital staining technique. The extraction of the polyphenols and flavonoids was effective, and more polyphenols per milligram of dissolved solids were obtained from P. alba than from Z. mistol. However, there were more flavonoids in Z. mistol than in P. alba. Components of both fruits increased the viability of cells treated with Stx when the extracts were preincubated with Stx for 1 h before being applied to the cell cultures, with the ethanolic extract of P. alba showing 95% cell viability at a concentration of 2.45 mg/ml. The extracts were less effective in protecting cells when Stx, extracts, and cells were coincubated together without a previous incubation of Stx; only the concentrations of 19.46 mg/ml for the P. alba aqueous extract and 3.75 mg/ml for the Z. mistol ethanolic extract resulted in the inhibition of cytotoxicity, with 52 and 56% cell viability occurring, respectively. Investigation into this difference in the protection of cells indicated that the protein molecule of Stx suffered degradation to advanced oxidative protein products during preincubation with extracts, principally with P. alba, which exhibited a greater amount of nonflavonoid polyphenols than Z. mistol. The prooxidant action on Stx favored the cells and enhanced the protective action of both fruits.

Relationship of advanced oxidative protein products in human saliva and plasma: age- and gender-related changes and stability during storage

The blood levels of advanced oxidative protein products (AOPP) elevate in aging and age-related diseases. However, saliva AOPP in healthy humans have been unexplored. Thus, we investigated 143 Chinese healthy adults to assay age- and gender-related changes in saliva and plasma AOPP levels and the stability of saliva AOPP stored both at - 20°C and - 80°C. We found the mean AOPP levels in saliva and plasma of 119 subjects were 7.51 ± 3.20 and 28.31 ± 5.53 μmol/L (μM). An age-dependent increase was observed in both saliva and plasma AOPP levels. This increase was particularly significant in the elderly subjects compared with that in the young and middle-aged ones. A significant positive correlation among age, saliva and plasma AOPP levels was observed. No gender-dependent difference was observed in either saliva or plasma AOPP levels during the aging process. Furthermore, AOPP levels in the 24 saliva samples showed no significant change at every successive determination during 4 weeks at - 80°C, whereas those levels significantly increased after 7 days of storage at - 20°C. These results indicate the feasibility to screen aging biochemical indicators using saliva AOPP as an alternative to blood AOPP. Saliva AOPP samples are suitable to be stored at - 80°C.

Lipid and protein oxidation products, antioxidant status and vascular complications in poorly controlled type 2 diabetes

The inter-relationships between glycaemic control, the progression of diabetes-related vascular complications, oxidative/antioxidative status and inflammation, have not been fully understood. We measured malondialdehyde (MDA) and carbonyl residues, C-reactive protein (CRP) and antioxidant systems by means of ferric reducing ability of plasma (FRAP) and superoxide dismutase (SOD) activity, in well controlled and poorly controlled type 2 diabetic patients without complications (NC) and in poorly controlled patients with microvascular (MicroVC) and with both micro- and macrovascular complications (Micro+Macro VC). All poorly controlled diabetic patients showed higher MDA and carbonyl residues compared to well controlled NC, as did those with Micro+Macro VC compared to poorly controlled NC. The higher CRP and SOD activity levels reached significance in Micro VC and Micro+Macro VC groups. FRAP decreased only in poorly controlled NC compared to well controlled NC (p<0.05). Glycated hamemoglobin (HbA1c) levels were positively correlated with MDA (p<0.05) and CRP (p<0.001) and inversely associated with FRAP (p<0.05) and SOD (p=0.06). An increase in MDA or carbonyl residues could be a marker of high risk for complications in patients with poorly controlled diabetes and they should be considered for monitoring the effectiveness of drug treatment.