Formation of 8-hydroxy-2'-deoxyguanosine and 4-hydroxy-2-nonenal-modified proteins in rat liver after ischemia-reperfusion: distinct localization of the two oxidatively modified products

Maternal diesel particle exposure alters gut microbiota and induces lung injury in rat offspring

Maternal air pollutant exposure inhibits fetal lung development. Diesel exhaust particles (DEP) are one of the most substantial contributors to particulate matter pollution. The effects of maternal DEP exposure on gut microbiota in mothers and offspring and fetal lung development remain unclear. In this study, time-dated pregnant Sprague Dawley rats received intranasal administration of 100 μL phosphate-buffered saline (PBS) or DEP (250 μg) in 100 μL PBS from gestational days 16-21. The dams were permitted to deliver vaginally at term. On postnatal days 0 and 7, gut microbiota was sampled from the lower gastrointestinal tract. The right lung and terminal ileum were harvested for histological, cytokine, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) analyses. On postnatal day 0, the dams exposed to DEP and rat offspring with maternal DEP exposure exhibited macrophages that phagocytized diesel particles and increased numbers of macrophages in the alveolar parenchyma. On postnatal days 0 and 7, the offspring of DEP-exposed dams exhibited significantly lower intestinal tight junction protein expression, higher lung 8-OHdG and cytokine levels, and substantial lung injury compared with the offspring of the control dams. No significant differences were observed in the microbiota composition and diversity between the control and DEP-exposed dams. Maternal DEP exposure altered the gut microbiota composition and diversity on postnatal days 0 and 7, with more significant effects observed in the offspring on postnatal day 7. Regarding the mechanism, lung injury in offspring may have been linked to altered gut microbiota communities and dysregulated metabolic pathways caused by maternal DEP exposure.

Novel, Innovative Models to Study Ischemia/Reperfusion-Related Redox Damage in Organ Transplantation

The implementation of ex vivo organ machine perfusion (MP) into clinical routine undoubtedly helped to increase the donor pool. It enables not just organ assessment, but potentially regeneration and treatment of marginal organs in the future. During organ procurement, redox-stress triggered ischemia-reperfusion injury (IRI) is inevitable, which in addition to pre-existing damage negatively affects such organs. Ex vivo MP enables to study IRI-associated tissue damage and its underlying mechanisms in a near to physiological setting. However, research using whole organs is limited and associated with high costs. Here, in vitro models well suited for early stage research or for studying particular disease mechanisms come into play. While cell lines convince with simplicity, they do not exert all organ-specific functions. Tissue slice cultures retain the three-dimensional anatomical architecture and cells remain within their naïve tissue-matrix configuration. Organoids may provide an even closer modelling of physiologic organ function and spatial orientation. In this review, we discuss the role of oxidative stress during ex vivo MP and the suitability of currently available in vitro models to further study the underlying mechanisms and to pretest potential treatment strategies.

Iron as spirit of life to share under monopoly

Any independent life requires iron to survive. Whereas iron deficiency causes oxygen insufficiency, excess iron is a risk for cancer, generating a double-edged sword. Iron metabolism is strictly regulated via specific systems, including iron-responsive element (IRE)/iron regulatory proteins (IRPs) and the corresponding ubiquitin ligase FBXL5. Here we briefly reflect the history of bioiron research and describe major recent advancements. Ferroptosis, a newly coined Fe(II)-dependent regulated necrosis, is providing huge impact on science. Carcinogenesis is a process to acquire ferroptosis-resistance and ferroptosis is preferred in cancer therapy due to immunogenicity. Poly(rC)-binding proteins 1/2 (PCBP1/2) were identified as major cytosolic Fe(II) chaperone proteins. The mechanism how cells retrieve stored iron in ferritin cores was unraveled as ferritinophagy, a form of autophagy. Of note, ferroptosis may exploit ferritinophagy during the progression. Recently, we discovered that cellular ferritin secretion is through extracellular vesicles (EVs) escorted by CD63 under the regulation of IRE/IRP system. Furthermore, this process was abused in asbestos-induced mesothelial carcinogenesis. In summary, cellular iron metabolism is tightly regulated by multi-system organizations as surplus iron is shared through ferritin in EVs among neighbor and distant cells in need. However, various noxious stimuli dramatically promote cellular iron uptake/storage, which may result in ferroptosis.

A systematic review of molecular approaches that link mitochondrial dysfunction and neuroinflammation in Parkinson's disease

Parkinson's disease (PD) is a chronic and progressive neurodegenerative disorder that affects 1% of the population worldwide. Etiology of PD is likely to be multi-factorial such as protein misfolding, mitochondrial dysfunction, oxidative stress, and neuroinflammation that contributes to the pathology of Parkinson's disease (PD), numerous studies have shown that mitochondrial dysfunction may play a key role in the dopaminergic neuronal loss. In multiple ways, the two most important are the activation of neuroinflammation and mitochondrial dysfunction, while mitochondrial dysfunction could cause neuroinflammation and vice versa. Thus, the mitochondrial proteins are the highly promising target for the development of PD. However, the limited amount of dopaminergic neurons prevented the detailed investigation of Parkinson's disease with regard to mitochondrial dysfunction. Both genetic and environmental factors are also associated with mitochondrial dysfunction and PD pathogenesis. The induction of PD by neurotoxins that inhibit mitochondrial complex I provide direct evidence linking mitochondrial dysfunction to PD. A decrease of mitochondrial complex I activity is observed in PD brain and in neurotoxin- or genetic factor-induced in vitro and in vivo models. Moreover, PINK1, Parkin, DJ-1 and LRRK2 mitochondrial PD gene products have important roles in mitophagy, a cellular process that clear damaged mitochondria. This review paper would discuss the evidence for the mitochondrial dysfunction and neuroinflammation in PD.

Immunization with anti-Tn immunogen in maternal rats protects against hyperoxia-induced kidney injury in newborn offspring

BACKGROUND

Neonatal hyperoxia increases oxidative stress and adversely disturbs glomerular and tubular maturity. Maternal Tn immunization induces anti-Tn antibody titer and attenuates hyperoxia-induced lung injury in neonatal rats.

METHODS

We intraperitoneally immunized female Sprague-Dawley rats (6 weeks old) with Tn immunogen (50 μg/dose) or carrier protein five times at biweekly intervals on 8, 6, 4, 2, and 0 weeks before the delivery day. The pups were reared for 2 weeks in either room air (RA) or in 85% oxygen-enriched atmosphere (O₂), thus generating four study groups, namely carrier protein + RA, Tn vaccine + RA, carrier protein + O₂, and Tn vaccine + O₂. On postnatal day 14, the kidneys were harvested for the oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG), nuclear factor-κB (NF-κB), and collagen expression and histological analyses.

RESULTS

Hyperoxia reduced body weight, induced tubular and glomerular injuries, and increased 8-OHdG and NF-κB expression and collagen deposition in the kidneys. By contrast, maternal Tn immunization reduced kidney injury and collagen deposition in neonatal rats. Furthermore, kidney injury attenuation was accompanied by a reduction in 8-OHdG and NF-κB expression.

CONCLUSION

Maternal Tn immunization protects against hyperoxia-induced kidney injury in neonatal rats by attenuating oxidative stress and NF-κB activity.

IMPACT

Hyperoxia increased nuclear factor-κB (NF-κB) activity and collagen deposition in neonatal rat kidney. Maternal Tn immunization reduced kidney injury as well as collagen deposition in neonatal rats. Maternal Tn immunization reduced kidney injury and was associated with a reduction in 8-hydroxy-2'-deoxyguanosine and NF-κB activity. Tn vaccine can be a promising treatment modality against hyperoxia-induced kidney injury in neonates.

Maternal Tn Immunization Attenuates Hyperoxia-Induced Lung Injury in Neonatal Rats Through Suppression of Oxidative Stress and Inflammation

Hyperoxia therapy is often required to treat newborns with respiratory disorders. Prolonged hyperoxia exposure increases oxidative stress and arrests alveolar development in newborn rats. Tn antigen is N-acetylgalactosamine residue that is one of the most remarkable tumor-associated carbohydrate antigens. Tn immunization increases the serum anti-Tn antibody titers and attenuates hyperoxia-induced lung injury in adult mice. We hypothesized that maternal Tn immunizations would attenuate hyperoxia-induced lung injury through the suppression of oxidative stress in neonatal rats. Female Sprague-Dawley rats (6 weeks old) were intraperitoneally immunized five times with Tn (50 μg/dose) or carrier protein at biweekly intervals on 8, 6, 4, 2, and 0 weeks before the day of delivery. The pups were reared in room air (RA) or 2 weeks of 85% O₂, creating the four study groups: carrier protein + RA, Tn vaccine + RA, carrier protein + O₂, and Tn vaccine + O₂. The lungs were excised for oxidative stress, cytokine, vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) expression, and histological analysis on postnatal day 14. Blood was withdrawn from dams and rat pups to check anti-Tn antibody using western blot. We observed that neonatal hyperoxia exposure reduced the body weight, increased 8-hydroxy-2-deoxyguanosine (8-OHdG) expression and lung cytokine (interleukin-4), increased mean linear intercept (MLI) values, and decreased vascular density and VEGF and PDGF-B expressions. By contrast, Tn immunization increased maternal and neonatal serum anti-Tn antibody titers on postnatal day 14, reduced MLI, and increased vascular density and VEGF and PDGF-B expressions to normoxic levels. Furthermore, the alleviation of lung injury was accompanied by a reduction in lung cytokine and 8-OHdG expression. Therefore, we propose that maternal Tn immunization attenuates hyperoxia-induced lung injury in neonatal rats through the suppression of oxidative stress and inflammation.

Hyperglycemia induces epithelial-mesenchymal transition in the lungs of experimental diabetes mellitus

Diabetes mellitus (DM) reduces lung function and increases the risk of asthma, chronic obstructive pulmonary disease, pneumonia, and pulmonary fibrosis. Epithelial-mesenchymal transition (EMT) plays a crucial role in the development of pulmonary fibrosis. The pathogenesis of pulmonary fibrosis in diabetes remains unknown. We investigated the effects of hyperglycemia on EMT in the lungs of gerbils with streptozotocin (STZ)-induced diabetes. Diabetic gerbils exhibited a significantly lower volume fraction of the alveolar airspace and significantly higher septal thickness, volume fraction of the alveolar wall, and lung injury scores than did nondiabetic gerbils. The percentage of 8-hydroxy-2'-deoxyguanosine-positive cells and transforming growth factor-β-positive cells was significantly higher, the expression of E-cadherin was significantly lower, and the expression of N-cadherin was significantly higher in diabetic gerbils than in nondiabetic gerbils. These EMT characteristics were associated with a significant increase in α-smooth muscle actin (SMA) expression and collagen deposition in the lungs of diabetic gerbils. The increased α-SMA expression was co-localized with surfactant protein-C in alveolar type II cells in hyperglycemic animals. In conclusion, our study demonstrates that hyperglycemia induces EMT and contributes to lung fibrosis in an experimental DM model.

Pain-reducing anesthesia prevents oxidative stress in human term placenta

Anesthesia is sometimes used for the reduction of maternal pain in normal human term labor, but whether the drugs affect oxidative stress remains unclear. The placenta serves as an interface between the maternal and fetal vasculature. In this study, we immunohistochemically analyzed two markers for oxidative stress, namely 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 4-hydroxy-2-nonenal–modified proteins (HNE), using placentas from 21 cases of normal tansvaginal delivery (V group), 20 Caesarean sections (C group), and 17 normal transvaginal deliveries with epidural anesthesia (E group). 8-OHdG staining in the nuclei of trophoblasts lining the chorionic villi was significantly stronger in the V group either compared with the C or E group (p<0.001), without significant differences in the C and E groups (p = 0.792). Moderate to intense staining by HNE of the intravascular serum of chorionic villi vasculature was frequently observed in the placentas from the V group, but less frequently of those in either C or E groups (p<0.001), nor the p value comparing the C and E groups was significant (p = 0.128) for HNE staining. Our results suggest that although the role of oxidative stress and its influences on fetal state in the placenta in labor remains unclear, it seems to be lessened by epidural anesthesia.

Neonatal Hyperoxia Exposure Induces Kidney Fibrosis in Rats

BACKGROUND

Human and animal studies have demonstrated that neonatal hyperoxia increases oxidative stress and adversely affects glomerular and tubular maturity. This study was undertaken to determine how exposure to neonatal hyperoxia affected kidney morphology and fibrosis and to elucidate the relationship between connective tissue growth factor (CTGF) and collagen expression in rat kidneys.

METHODS

Sprague-Dawley rat pups were exposed to either hyperoxia or ambient air. The control groups were maintained in ambient air for 1 week and 3 weeks. The hyperoxia groups were exposed to >95% O2 for 1 week and subsequently placed in an environment of 60% O2 for an additional 2 weeks. The animals were euthanized on Postnatal Day 7 or 21 and the kidneys underwent histological analyses and oxidative stress and total collagen measurements.

RESULTS

The rats reared in O2-enriched air exhibited significantly higher tubular injury scores (1.4 ± 0.5 vs. 0.7 ± 0.7 on Day 7; 1.4 ± 0.5 vs. 0.6 ± 0.5 on Day 21), a larger proportion of the cortex occupied by glomeruli (25.5 ± 4.1 vs. 21.3 ± 3.1% on Day 7; 20.1 ± 3.5 vs. 17.1 ± 1.7% on Day 21), larger glomerular sizes (84.7 ± 5.8 vs. 77.5 ± 6.1 μm on Day 7; 88.4 ± 2.9 vs. 84.9 ± 3.1 μm on Day 21), and higher total collagen content (54.1 ± 27.5 vs. 18.3 ± 6.3 μg/mg protein on Day 7; 397.4 ± 32.8 vs. 289.5 ± 80.0 μg/mg protein on Day 21) than did rats reared in ambient air. Immunohistochemical expressions of oxidative stress marker 8-hydroxy-2'-deoxyguanosine and CTGF immunoreactivities were significantly higher in the rats reared in O2-enriched air compared with the rats reared in ambient air on Postnatal Days 7 and 21.

CONCLUSION

Neonatal hyperoxia exposure contributes to kidney fibrosis, which is probably caused by activated CTGF expression.

Maternal Nicotine Exposure Induces Epithelial-Mesenchymal Transition in Rat Offspring Lungs

BACKGROUND

Maternal nicotine exposure induces lung injuries and fibrosis in rat offspring. Epithelial-mesenchymal transition (EMT) following lung injury is a process in which epithelial cells mediate tissue repair.

OBJECTIVE

To determine the effects of maternal nicotine exposure on EMT in neonatal rat lungs.

METHODS

Nicotine was administered to pregnant Sprague-Dawley rats using a subcutaneous osmotic minipump that delivered a dose of 6 mg/kg/day on gestational days 7-21 or from gestational day 7 to postnatal day 14. A control group received an equal volume of saline.

RESULTS

The percentage of 8-hydroxy-2'-deoxyguanosine-positive cells in nuclear staining was significantly higher, the E-cadherin protein expression was significantly lower, and the N-cadherin protein expression was significantly higher in rats born to prenatal and postnatal nicotine-treated dams than in those born to prenatal saline- and nicotine-treated dams on postnatal day 7. These characteristics of EMT were associated with a significant increase in α-smooth muscle actin (SMA) expression on postnatal day 21. Rats born to prenatal and postnatal nicotine-treated dams showed significantly higher α-SMA expression and total collagen than those born to prenatal saline- and nicotine-treated dams on postnatal day 21. The number of cells expressing fibroblast-specific protein 1 and vimentin was higher in rats born to prenatal and postnatal nicotine-treated dams than in those born to prenatal saline- and nicotine-treated dams on postnatal days 7 and 21.

CONCLUSIONS

Maternal nicotine exposure during gestation and lactation induces EMT and contributes to lung fibrosis in rat offspring.

Lipid hydroperoxide-derived modification of proteins in gastrointestinal tract

Role of lipid peroxidation in the pathogenesis of gastrointestinal diseases has been evaluated by measuring the tissue levels of lipid peroxides as thiobarbituric acid-reactive substances in the animal models as well as human. Recently, N (ε)-(hexanoyl)lysine (HEL) and 4-hydroxy-2-nonenal (HNE) are recognized as reliable and sensitive biomarkers for the early phase and the late phase of lipid peroxidation, respectively. The presence of HNE- and HEL-modified proteins has been demonstrated in in vivo models of several gastrointestinal diseases. In the present review, we introduced HNE-modification of TRPV1 channel in esophageal epithelial cells, HEL-modification of tropomyosin 1 (TMP1) in gastric cancer cells, and HEL-modification of gastrokine 1 in the healing of gastric ulcer.

Replication bypass of the trans-4-Hydroxynonenal-derived (6S,8R,11S)-1,N(2)-deoxyguanosine DNA adduct by the sulfolobus solfataricus DNA polymerase IV

trans-4-Hydroxynonenal (HNE) is the major peroxidation product of ω-6 polyunsaturated fatty acids in vivo. Michael addition of the N(2)-amino group of dGuo to HNE followed by ring closure of N1 onto the aldehyde results in four diastereomeric 1,N(2)-dGuo (1,N(2)-HNE-dGuo) adducts. The (6S,8R,11S)-HNE-1,N(2)-dGuo adduct was incorporated into the 18-mer templates 5'-d(TCATXGAATCCTTCCCCC)-3' and d(TCACXGAATCCTTCCCCC)-3', where X = (6S,8R,11S)-HNE-1,N(2)-dGuo adduct. These differed in the identity of the template 5'-neighbor base, which was either Thy or Cyt, respectively. Each of these templates was annealed with either a 13-mer primer 5'-d(GGGGGAAGGATTC)-3' or a 14-mer primer 5'-d(GGGGGAAGGATTCC)-3'. The addition of dNTPs to the 13-mer primer allowed analysis of dNTP insertion opposite to the (6S,8R,11S)-HNE-1,N(2)-dGuo adduct, whereas the 14-mer primer allowed analysis of dNTP extension past a primed (6S,8R,11S)-HNE-1,N(2)-dGuo:dCyd pair. The Sulfolobus solfataricus P2 DNA polymerase IV (Dpo4) belongs to the Y-family of error-prone polymerases. Replication bypass studies in vitro reveal that this polymerase inserted dNTPs opposite the (6S,8R,11S)-HNE-1,N(2)-dGuo adduct in a sequence-specific manner. If the template 5'-neighbor base was dCyt, the polymerase inserted primarily dGTP, whereas if the template 5'-neighbor base was dThy, the polymerase inserted primarily dATP. The latter event would predict low levels of Gua → Thy mutations during replication bypass when the template 5'-neighbor base is dThy. When presented with a primed (6S,8R,11S)-HNE-1,N(2)-dGuo:dCyd pair, the polymerase conducted full-length primer extension. Structures for ternary (Dpo4-DNA-dNTP) complexes with all four template-primers were obtained. For the 18-mer:13-mer template-primers in which the polymerase was confronted with the (6S,8R,11S)-HNE-1,N(2)-dGuo adduct, the (6S,8R,11S)-1,N(2)-dGuo lesion remained in the ring-closed conformation at the active site. The incoming dNTP, either dGTP or dATP, was positioned with Watson-Crick pairing opposite the template 5'-neighbor base, dCyt or dThy, respectively. In contrast, for the 18-mer:14-mer template-primers with a primed (6S,8R,11S)-HNE-1,N(2)-dGuo:dCyd pair, ring opening of the adduct to the corresponding N(2)-dGuo aldehyde species occurred. This allowed Watson-Crick base pairing at the (6S,8R,11S)-HNE-1,N(2)-dGuo:dCyd pair.

Formation of a N2-dG:N2-dG carbinolamine DNA cross-link by the trans-4-hydroxynonenal-derived (6S,8R,11S) 1,N2-dG adduct

Michael addition of trans-4-hydroxynonenal (HNE) to deoxyguanosine yields diastereomeric 1,N²-dG adducts in DNA. When placed opposite dC in the 5′-CpG-3′ sequence, the (6S,8R,11S) diastereomer forms a N²-dG:N²-dG interstrand cross-link [Wang, H.; Kozekov, I. D.; Harris, T. M.; Rizzo, C. J. J. Am. Chem. Soc.2003, 125, 5687–5700]. We refined its structure in 5′-d(G¹C²T³A⁴G⁵C⁶X⁷A⁸G⁹T¹⁰C¹¹C¹²)-3′·5′-d(G¹³G¹⁴A¹⁵C¹⁶T¹⁷C¹⁸Y¹⁹C²⁰T²¹A²²G²³C²⁴)-3′ [X⁷ is the dG adjacent to the C6 carbon of the cross-link or the α-carbon of the (6S,8R,11S) 1,N²-dG adduct, and Y¹⁹ is the dG adjacent to the C8 carbon of the cross-link or the γ-carbon of the HNE-derived (6S,8R,11S) 1,N²-dG adduct; the cross-link is in the 5′-CpG-3′ sequence]. Introduction of ¹³C at the C8 carbon of the cross-link revealed one ¹³C8→H8 correlation, indicating that the cross-link existed predominantly as a carbinolamine linkage. The H8 proton exhibited NOEs to Y¹⁹ H1′, C²⁰ H1′, and C²⁰ H4′, orienting it toward the complementary strand, consistent with the (6S,8R,11S) configuration. An NOE was also observed between the HNE H11 proton and Y¹⁹ H1′, orienting the former toward the complementary strand. Imine and pyrimidopurinone linkages were excluded by observation of the Y¹⁹N²H and X⁷ N1H protons, respectively. A strong H8→H11 NOE and no ³J(¹³C→H) coupling for the ¹³C8–O–C11–H11 eliminated the tetrahydrofuran species derived from the (6S,8R,11S) 1,N²-dG adduct. The (6S,8R,11S) carbinolamine linkage and the HNE side chain were located in the minor groove. The X⁷N² and Y¹⁹N² atoms were in the gauche conformation with respect to the linkage, maintaining Watson–Crick hydrogen bonds at the cross-linked base pairs. A solvated molecular dynamics simulation indicated that the anti conformation of the hydroxyl group with respect to C6 of the tether minimized steric interaction and predicted hydrogen bonds involving O8H with C²⁰O² of the 5′-neighbor base pair G⁵·C²⁰ and O11H with C¹⁸O² of X⁷·C¹⁸. These may, in part, explain the stability of this cross-link and the stereochemical preference for the (6S,8R,11S) configuration.

DNA cross-link induced by trans-4-hydroxynonenal

Trans-4-Hydroxynonenal (HNE) is a peroxidation product of omega-6 polyunsaturated fatty acids. Michael addition of HNE to deoxyguanosine yields four diastereomeric 1,N(2)-dG adducts. The adduct of (6S,8R,11S) stereochemistry forms interstrand N(2)-dG:N(2)-dG cross-links in the 5'-CpG-3' sequence. It has been compared with the (6R,8S,11R) adduct, incorporated into 5'-d(GCTAGCXAGTCC)-3' . 5'-d(GGACTCGCTAGC)-3', containing the 5'-CpG-3' sequence (X = HNE-dG). Both adducts rearrange in DNA to N(2)-dG aldehydes. These aldehydes exist in equilibrium with diastereomeric cyclic hemiacetals, in which the latter predominate at equilibrium. These cyclic hemiacetals mask the aldehydes, explaining why DNA cross-linking is slow compared to related 1,N(2)-dG adducts formed by acrolein and crotonaldehyde. Both the (6S,8R,11S) and (6R,8S,11R) cyclic hemiacetals are located within the minor groove. However, the (6S,8R,11S) cyclic hemiacetal orients in the 5'-direction, while the (6R,8S,11R) cyclic hemiacetal orients in the 3'-direction. The conformations of the diastereomeric N(2)-dG aldehydes, which are the reactive species involved in DNA cross-link formation, have been calculated using molecular mechanics methods. The (6S,8R,11S) aldehyde orients in the 5'-direction, while the (6R,8S,11R) aldehyde orients in the 3'-direction. This suggests a kinetic basis to explain, in part, why the (6S,8R,11S) HNE adduct forms interchain cross-links in the 5'-CpG-3' sequence, whereas (6R,8S,11R) HNE adduct does not. The presence of these cross-links in vivo is anticipated to interfere with DNA replication and transcription, thereby contributing to the etiology of human disease.

Conformational interconversion of the trans-4-hydroxynonenal-derived (6S,8R,11S) 1,N(2)-deoxyguanosine adduct when mismatched with deoxyadenosine in DNA

The (6S,8R,11S) 1,N(2)-HNE-dGuo adduct of trans-4-hydroxynonenal (HNE) was incorporated into the duplex 5'-d(GCTAGCXAGTCC)-3'.5'-d(GGACTAGCTAGC)-3' [X = (6S,8R,11S) HNE-dG], in which the lesion was mismatched opposite dAdo. The (6S,8R,11S) adduct maintained the ring-closed 1,N(2)-HNE-dG structure. This was in contrast to when this adduct was correctly paired with dCyd, conditions under which it underwent ring opening and rearrangement to diastereomeric minor groove cyclic hemiacetals [ Huang , H. , Wang , H. , Qi , N. , Lloyd , R. S. , Harris , T. M. , Rizzo , C. J. , and Stone , M. P. ( 2008 ) J. Am. Chem. Soc. 130 , 10898 - 10906 ]. The (6S,8R,11S) adduct exhibited a syn/anti conformational equilibrium about the glycosyl bond. The syn conformation was predominant in acidic solution. Structural analysis of the syn conformation revealed that X(7) formed a distorted base pair with the complementary protonated A(18). The HNE moiety was located in the major groove. Structural perturbations were observed at the neighbor C(6).G(19) and A(8).T(17) base pairs. At basic pH, the anti conformation of X(7) was the major species. The 1,N(2)-HNE-dG intercalated and displaced the complementary A(18) in the 5'-direction, resulting in a bulge at the X(7).A(18) base pair. The HNE aliphatic chain was oriented toward the minor groove. The Watson-Crick hydrogen bonding of the neighboring A(8).T(17) base pair was also disrupted.

The stereochemistry of trans-4-hydroxynonenal-derived exocyclic 1,N2-2'-deoxyguanosine adducts modulates formation of interstrand cross-links in the 5'-CpG-3' sequence

The trans-4-hydroxynonenal (HNE)-derived exocyclic 1, N(2)-dG adduct with (6S,8R,11S) stereochemistry forms interstrand N(2)-dG-N(2)-dG cross-links in the 5'-CpG-3' DNA sequence context, but the corresponding adduct possessing (6R,8S,11R) stereochemistry does not. Both exist primarily as diastereomeric cyclic hemiacetals when placed into duplex DNA [Huang, H., Wang, H., Qi, N., Kozekova, A., Rizzo, C. J., and Stone, M. P. (2008) J. Am. Chem. Soc. 130, 10898-10906]. To explore the structural basis for this difference, the HNE-derived diastereomeric (6S,8R,11S) and (6R,8S,11R) cyclic hemiacetals were examined with respect to conformation when incorporated into 5'-d(GCTAGC XAGTCC)-3' x 5'-d(GGACTCGCTAGC)-3', containing the 5'-CpX-3' sequence [X = (6S,8R,11S)- or (6R,8S,11R)-HNE-dG]. At neutral pH, both adducts exhibited minimal structural perturbations to the DNA duplex that were localized to the site of the adduction at X(7) x C(18) and its neighboring base pair, A(8) x T(17). Both the (6S,8R,11S) and (6R,8S,11R) cyclic hemiacetals were located within the minor groove of the duplex. However, the respective orientations of the two cyclic hemiacetals within the minor groove were dependent upon (6S) versus (6R) stereochemistry. The (6S,8R,11S) cyclic hemiacetal was oriented in the 5'-direction, while the (6R,8S,11R) cyclic hemiacetal was oriented in the 3'-direction. These cyclic hemiacetals effectively mask the reactive aldehydes necessary for initiation of interstrand cross-link formation. From the refined structures of the two cyclic hemiacetals, the conformations of the corresponding diastereomeric aldehydes were predicted, using molecular mechanics calculations. Potential energy minimizations of the duplexes containing the two diastereomeric aldehydes predicted that the (6S,8R,11S) aldehyde was oriented in the 5'-direction while the (6R,8S,11R) aldehyde was oriented in the 3'-direction. These stereochemical differences in orientation suggest a kinetic basis that explains, in part, why the (6S,8R,11S) stereoisomer forms interchain cross-links in the 5'-CpG-3' sequence whereas the (6R,8S,11R) stereoisomer does not.

Rearrangement of the (6S,8R,11S) and (6R,8S,11R) exocyclic 1,N2-deoxyguanosine adducts of trans-4-hydroxynonenal to N2-deoxyguanosine cyclic hemiacetal adducts when placed complementary to cytosine in duplex DNA

trans-4-Hydroxynonenal (HNE) is a peroxidation product of omega-6 polyunsaturated fatty acids. The Michael addition of deoxyguanosine to HNE yields four diastereomeric exocyclic 1,N(2)-dG adducts. The corresponding acrolein- and crotonaldehyde-derived exocyclic 1,N(2)-dG adducts undergo ring-opening to N(2)-dG aldehydes, placing the aldehyde functionalities into the minor groove of DNA. The acrolein- and the 6R-crotonaldehyde-derived exocyclic 1,N(2)-dG adducts form interstrand N(2)-dG:N(2)-dG cross-links in the 5'-CpG-3' sequence context. Only the HNE-derived exocyclic 1,N(2)-dG adduct of (6S,8R,11S) stereochemistry forms interstrand N(2)-dG:N(2)-dG cross-links in the 5'-CpG-3' sequence context. Moreover, as compared to the exocyclic 1,N(2)-dG adducts of acrolein and crotonaldehyde, the cross-linking reaction is slow (Wang, H.; Kozekov, I. D.; Harris, T. M.; Rizzo, C. J. J. Am. Chem. Soc. 2003, 125, 5687-5700). Accordingly, the chemistry of the HNE-derived exocyclic 1,N(2)-dG adduct of (6S,8R,11S) stereochemistry has been compared with that of the (6R,8S,11R) adduct, when incorporated into 5'-d(GCTAGCXAGTCC)-3'.5'-d(GGACTCGCTAGC)-3', containing the 5'-CpG-3' sequence (X = HNE-dG). When placed complementary to dC in this duplex, both adducts open to the corresponding N(2)-dG aldehydic rearrangement products, suggesting that the formation of the interstrand cross-link by the exocyclic 1,N(2)-dG adduct of (6S,8R,11S) stereochemistry, and the lack of cross-link formation by the exocyclic 1,N(2)-dG adduct of (6R,8S,11R) stereochemistry, is not attributable to inability to undergo ring-opening to the aldehydes in duplex DNA. Instead, these aldehydic rearrangement products exist in equilibrium with stereoisomeric cyclic hemiacetals. The latter are the predominant species present at equilibrium. The trans configuration of the HNE H6 and H8 protons is preferred. The presence of these cyclic hemiacetals in duplex DNA is significant as they mask the aldehyde species necessary for interstrand cross-link formation.

A New Amphiphilic Derivative,N-{[4-(Lactobionamido)methyl]benzylidene}- 1,1-dimethyl-2-(octylsulfanyl)ethylamineN-Oxide, Has a Protective Effect Against Copper-Induced Fulminant Hepatitis inLong–Evans Cinnamon Rats at an Extremely Low Concentration Compared with Its Original Formα-Phenyl-N-(tert-butyl) Nitrone

An amphiphilic alpha-phenyl-N-(tert-butyl) nitrone (PBN) derivative, N-{[4-(lactobionamido)methyl]benzylidene}-1,1-dimethyl-2-(octylsulfanyl)ethylamine N-oxide (LPBNSH), newly synthesized from its original form PBN in hopes of clinical use, was intraperitoneally administered to Long-Evans Cinnamon (LEC) rats every 2 days at the concentrations of 0.1, 0.5, 1.0, and 2.0 mg/kg. We found that LPBNSH protected against copper-induced hepatitis with jaundice in LEC rats at concentrations of 0.1 and 0.5 mg/kg, which were extremely low compared with that of PBN. It also effectively prevented the loss of body weight, reduced the death rate, and suppressed the increase in serum aspartate aminotransferase and alanine aminotransferase values arising from fulminant hepatitis with jaundice at the same concentrations. Similar results were observed when PBN was administered at the concentration of 150 mg/kg. Immunohistochemical analysis of 8-hydroxy-2'-deoxyguanosine and measurement of thiobarbituric acid-reactive substances in the liver showed that LPBNSH largely suppressed the formation of these oxidative products at same concentrations. No difference in the abnormal accumulation of copper in the liver between the LPBNSH administered and control groups was observed. From these results, it was concluded that LPBNSH exhibited liver-protective effects against fulminant hepatitis with jaundice at ca. 1/1000, 500 the molar concentration of PBN and, therefore, was clinically promising.

Expression of oxidative stress-related molecules in circulating leukocytes and urine in patients with chronic viral hepatitis

AIMS

Oxidative stress plays a role in pathogenesis of chronic viral hepatitis. Expression of oxidative stress-related molecules remains to be clarified.

METHODS

4-hydroxy-2-nonenal (4-HNE), 4-hydroxy-2-hexenal (4-HHE), catalase, superoxide dismutase-1 (SOD-1), glutathione peroxidase-1, thioredoxin (TRX) in leukocytes and urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) were examined in 164 persons, including 130 chronic viral hepatitis patients and 34 normal individuals, by Western blot analysis and enzyme-linked immunosorbent assay, respectively. Hepatic expression of these proteins was immunohistochemically examined in 12 patients with chronic viral hepatitis, compared with three persons without liver damage.

RESULTS

The 4-HNE/beta-actin ratios in chronic viral hepatitis were significantly higher than those in normal individuals (P<0.01), and were significantly correlated with asparate aminotransferase (AST) and alanine aminotransferase (ALT) (P<0.01, each). The catalase/beta-actin and SOD-1/beta-actin ratios in chronic viral hepatitis were higher than those in normal individuals, and were significantly correlated with 4-HNE/beta-actin ratios (P<0.01, each). Hepatic expression of 4-HNE, 4-HHE, catalase, SOD-1 and TRX in chronic viral hepatitis was higher than that without liver damage. Urinary excretion of 8-OHdG was not changed in chronic viral hepatitis.

CONCLUSIONS

The results of the present study suggest that expression of oxidative stress-related molecules in leukocytes is upregulated in relation to serum aminotransferase levels.

Determination of 8-oxoguanine and 8-hydroxy-2'-deoxyguanosine in the rat cerebral cortex using microdialysis sampling and capillary electrophoresis with electrochemical detection

A rapid and sensitive method to determine 8-oxoguanine (8oxoG) and 8-hydroxydeoxyguanosine (8OHdG), biomarkers for oxidative DNA damage, in cerebral cortex microdialysate samples using capillary electrophoresis (CE) with electrochemical detection (CEEC) was developed. Samples were concentrated on-column using pH-mediated stacking for anions. On-column anodic detection was performed with a carbon fiber working electrode and laser-etched decoupler. The method is linear over the expected extracellular concentration range for 8oxoG and 8-OHdG during induced ischemia-reperfusion, with R.S.D. values Collapse

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MESH Headings

• Animals
• Biomarkers/analysis
• Cerebral Cortex/chemistry
• Chromatography, Liquid/methods
• Deoxyadenosines/analysis
• Electrochemistry
• Electrophoresis, Capillary/methods
• Female
• Guanine/analogs & derivatives
• Guanine/analysis
• Mass Spectrometry/methods
• Microdialysis/methods
• Rats
• Rats, Sprague-Dawley

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Grants

• R01 EB000247 NIBIB NIH HHS
• R01 HL069014-02 NHLBI NIH HHS
• R01EB00247 NIBIB NIH HHS
• T32 CA009242 NCI NIH HHS
• R01 HL069014 NHLBI NIH HHS
• T32CA09242 NCI NIH HHS

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Affiliation(s)

Stacy D. Arnett Department of Chemistry, University of Kansas, Lawrence, KS 66045
Damon M. Osbourn Department of Chemistry, University of Kansas, Lawrence, KS 66045
Kimberly D. Moore Department of Chemistry, University of Kansas, Lawrence, KS 66045
Shannon S. Vandaveer Department of Chemistry, University of Kansas, Lawrence, KS 66045
Craig E. Lunte Department of Chemistry, University of Kansas, Lawrence, KS 66045

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JNK mediates hepatic ischemia reperfusion injury

BACKGROUND/AIMS

Hepatic ischemia followed by reperfusion (I/R) is a major clinical problem during transplantation, liver resection for tumor, and circulatory shock, producing apoptosis and necrosis. Although several intracellular signal molecules are induced following I/R including NF-kappaB and c-Jun N terminal kinase (JNK), their roles in I/R injury are largely unknown. The aim of this study is to assess the role of JNK during warm I/R injury using novel selective JNK inhibitors.

METHODS

Male Wistar rats (200+/-25 g) are pretreated with vehicle or with one of three compounds (CC0209766, CC0223105, and CC-401), which are reversible, highly selective, ATP-competitive inhibitors of JNK. In the first study, rats are assessed for survival using a model of ischemia to 70% of the liver for 90 min followed by 30% hepatectomy of the non-ischemic lobes and then reperfusion. In the second study, rats are assessed for liver injury resulting from 60 or 90 min of ischemia followed by reperfusion with analysis over time of hepatic histology, serum ALT, hepatic caspase-3 activation, cytochrome c release, and lipid peroxidation.

RESULTS

In the I/R survival model, vehicle-treated rats have a 7-day survival of 20-40%, while rats treated with the three different JNK inhibitors have survival rates of 60-100% (P<0.05). The decrease in mortality correlates with improved hepatic histology and serum ALT levels. Vehicle treated rats have pericentral necrosis, neutrophil infiltration, and some apoptosis in both hepatocytes and sinusoidal endothelial cells, while JNK inhibitors significantly decrease both types of cell death. JNK inhibitors decrease caspase-3 activation, cytochrome c release from mitochondria, and lipid peroxidation. JNK inhibition transiently blocks phosphorylation of c-Jun at an early time point after reperfusion, and AP-1 activation is also substantially blocked. JNK inhibition blocks the upregulation of the pro-apoptotic Bak protein and the degradation of Bid.

CONCLUSIONS

Thus, JNK inhibitors decrease both necrosis and apoptosis, suggesting that JNK activity induces cell death by both pathways.

Lipid peroxidation during ischemia depends on ischemia time in warm ischemia and reperfusion of rat liver

Prolonged hepatic warm ischemia has been incriminated in oxidative stress after reperfusion. However, the magnitude of oxidative stress during ischemia has been controversial. The aims of the present study were to elucidate whether lipid peroxidation progressed during ischemia and to clarify whether oxidative stress during ischemia aggravated the oxidative damage after reperfusion. Rats were subjected to 30 to 120 min of 70% warm ischemia alone or followed by reperfusion for 60 min. Lipid peroxidation (LPO) was evaluated by amounts of phosphatidylcholine hydroperoxide (PC-OOH) and phosphatidylethanolamine hydroperoxide (PE-OOH) as primary LPO products. Total amounts of malondialdehyde and 4-hydroxy-2-nonenal (MDA + 4-HNE), degraded from hydroperoxides, were also determined. PC-OOH and PE-OOH significantly increased at 60 and 120 min ischemia with concomitant increase of oxidized glutathione. These hydroperoxides did not increase at 60 min reperfusion after 60 min ischemia, whereas they did increase at 60 min reperfusion after 120 min ischemia with deactivation of phospholipid hydroperoxide glutathione peroxidase and superoxide dismutase. The amount of MDA + 4-HNE exhibited similar changes, but the velocity of production dropped with ischemic time longer than 60 min. In conclusion, oxidative stress progressed during ischemia and triggered the oxidative injury after reperfusion. Secondary LPO products are less sensitive, especially during ischemia, which may cause possible underestimation and discrepancy.

Oxidative DNA damage and disease: induction, repair and significance

The generation of reactive oxygen species may be both beneficial to cells, performing a function in inter- and intracellular signalling, and detrimental, modifying cellular biomolecules, accumulation of which has been associated with numerous diseases. Of the molecules subject to oxidative modification, DNA has received the greatest attention, with biomarkers of exposure and effect closest to validation. Despite nearly a quarter of a century of study, and a large number of base- and sugar-derived DNA lesions having been identified, the majority of studies have focussed upon the guanine modification, 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-OH-dG). For the most part, the biological significance of other lesions has not, as yet, been investigated. In contrast, the description and characterisation of enzyme systems responsible for repairing oxidative DNA base damage is growing rapidly, being the subject of intense study. However, there remain notable gaps in our knowledge of which repair proteins remove which lesions, plus, as more lesions identified, new processes/substrates need to be determined. There are many reports describing elevated levels of oxidatively modified DNA lesions, in various biological matrices, in a plethora of diseases; however, for the majority of these the association could merely be coincidental, and more detailed studies are required. Nevertheless, even based simply upon reports of studies investigating the potential role of 8-OH-dG in disease, the weight of evidence strongly suggests a link between such damage and the pathogenesis of disease. However, exact roles remain to be elucidated.

Immunohistochemical study of myoglobin and oxidative injury-related markers in the kidney of methamphetamine abusers

It is known that methamphetamine (MA) causes rhabdomyolysis, myoglobinuria, and acute renal failure. We conducted an immunohistochemical study on the kidney of 22 forensic autopsy cases in which MA had been detected. Myoglobin was positive in 17 cases. The concentration of the blood MA in the myoglobin-positive cases (8.39+/-3.43 micromol/dl) was higher than -negative cases (0.198+/-0.076 micromol/dl). And, the 70 kDa heat shock protein (HSP70), 8-hydroxy-2'-deoxyguanosine (8-OH-dG), 4-hydroxy-2-nonenal (4-HNE), and Cu/Zn superoxide dismutase (SOD) were also stained positively in five, ten, 11, nine cases of examined, respectively. In addition, 80% of HSP70-positive cases were myoglobin-positive. Myoglobin was also observed in 60% of 8-OH-dG-positive, in 82% of 4-HNE-positive, and in 78% of SOD-positive cases, respectively. Therefore, myoglobin rather than MA itself might induce oxidative damage. From these results, it was considered that MA abuse had caused the skeletal muscle damage before death. In forensic autopsy cases of drug abusers, the antemortem situation is not often known. The present research suggested that in addition to the measurement of the concentration of MA, immunohistochemical staining of myoglobin, HSP70, 8-OH-dG, 4-HNE, and SOD offers important information for the diagnosis of MA poisoning.

Site-specific mutagenicity of stereochemically defined 1,N2-deoxyguanosine adducts of trans-4-hydroxynonenal in mammalian cells

Trans-4-hydroxynonenal (HNE) is a toxic compound produced endogenously during lipid peroxidation. HNE is a potent electrophile that is reactive with both proteins and nucleic acids. HNE preferentially reacts with deoxyguanosine to form four stereoisomeric HNE-deoxyguanosine (HNE-dG) adducts: (6R, 8S, 11R), (6S, 8R, 11S), (6R, 8S, 11S), and (6S, 8R, 11R). These adducts were synthesized into 12-mer oligodeoxynucleotides, inserted into a DNA shuttle vector and evaluated for the ability of each stereoisomer to induce mutagenesis when replicated through mammalian cells. The resultant mutagenicity of these adducts was related to their stereochemistry, in that two of the HNE-dG adducts, (6R, 8S, 11R) and (6S, 8R, 11S), were significantly more mutagenic than the (6R, 8S, 11S) and (6S, 8R, 11R) HNE-dG adducts. These data conclusively demonstrate that HNE-derived DNA adducts can be mutagenic in mammalian cells and their ability to cause mutations is dictated by their stereochemistry.