Role Of 4-HNE Research Articles

Reduced Lipid Peroxidation Predicts Unfavorable Prognosis in Hepatocellular Carcinoma, but Not Intrahepatic Cholangiocarcinoma.

Primary liver cancer, including hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA), remains a significant contributor to cancer-related mortality worldwide. Oxidative stress and lipid peroxidation play a key role in chronic liver diseases and have been shown to be pivotal for tumor initiation and progression. 4-hydroxy-nonenal (4-HNE), one of the major mediators of oxidative stress and a well-established biomarker for lipid peroxidation, can act as a signal transducer, inducing inflammation and exerting carcinogenic effects. However, the role of 4-HNE in primary liver cancer remains poorly explored. In this study, we investigated 4-HNE levels in 797 liver carcinomas, including 561 HCC and 236 iCCA, by immunohistochemistry. We then correlated 4-HNE levels with comprehensive clinical data and survival outcomes. In HCC, lower expression levels of 4-HNE were associated with vascular invasion, a high tumor grade, a macrotrabecular-massive HCC subtype, and poor overall survival. Concerning iCCA, large duct iCCA showed significantly higher 4-HNE levels when compared to small duct iCCA. Yet, in iCCA, 4-HNE levels did not correlate with known prognostic parameters or survival outcomes. To conclude, in HCC but not in iCCA, low amounts of 4-HNE predict unfavorable survival outcomes and are associated with aggressive tumor behavior. These findings provide insights into the role of 4-HNE in liver cancer progression and may enable novel therapeutic strategies.

Abstract 15145: Aldehyde Dehydrogenase 2 Agonist Reverses Fibroblast Activation in the End Stage Human Right Ventricle Failure via 3’Utr Regulation of Profibrotic Genes

Background: Cardiac fibrosis, a prominent feature of pressure overloaded right ventricle (RV) in pulmonary hypertension (PH), is fundamental to the development of right ventricle failure (RVF). We found that a defect in alternative polyadenylation (APA) of profibrotic genes is a driving factor that induces fibrosis. Oxidative stress-mediated reactive aldehydes, such as 4-hydroxy-2-nonenal (4HNE) contribute to fibrosis and extracellular matrix (ECM) remodeling. However, the role of 4HNE in APA is unknown. Methods: We compared isolated cardiac fibroblasts from the RVs of explanted transplanted hearts of recipients with pulmonary hypertension patients to control hearts. Results: Compared to controls, tissue and fibroblasts derived from failing RV human hearts have greater deposition of extracellular matrix (ECM) proteins, such as collagen type I alpha (COL1A) and fibronectin (FN1), the expression of alpha smooth muscle actin (α-SMA), indicative of myofibroblast differentiation, and nuclear factor kappa B subunit (NFκB), a transcription factor critical for profibrotic genes transcriptional activation. Moreover, alternative polyadenylation (APA) isoforms of mRNA for COL1A, FN1, NFκB, TGF-β1 and its receptor - transforming growth factor beta receptor 1 (TGFβR1) are associated with shortened 3’UTR in RVF tissues or fibroblasts. Likewise, reduced expression and activity of aldehyde dehydrogenase 2 (ALDH2) expression, a 4HNE detoxifying enzyme, correlated with increased 4HNE adduction in tissues and cardiac fibroblasts derived from RVF hearts. Moreover, ALDH2 activation by its agonist, Alda-1, decreased 4HNE adduction and oxidative stress and most importantly downregulated the gene and protein expression of profibrotic genes, simultaneously lengthening the 3’UTR of the previously shortened profibrotic genes. Conclusion: In RVF, fibroblasts express mRNA of profibrotic genes with shortened 3'UTRs, suggesting the feasibility of developing antifibrotic therapies targeting 3'UTRs in myofibroblasts. Furthermore, our findings suggest that Alda-1 has a therapeutic role in mitigating cardiac fibrosis in RVF hearts by attenuating 4HNE-mediated dysregulation of APA.

Abstract 204: Modification of AIFm2 By 4HNE Leads to Retrograde Stress Signaling During Ischemia- Reperfusion Injury in Heart

Myocardial infarction is a leading cause of death worldwide and occurs due to blockage in blood supply to the heart. Re-establishment of blood flow after a brief period of ischemia leads to paradoxical exacerbation of the cardiomyocyte and its death. This phenomenon is known as ischemia-reperfusion injury. Major evidence in the pathogenesis of ischemia-reperfusion injury is due to oxidative stress, which is an imbalance between reactive oxygen species (ROS) and antioxidants. Membrane consisting of polyunsaturated fatty acid is attacked by ROS leading to lipid peroxidation and the generation of one of the toxic aldehydes 4-hydroxynonenal (4-HNE). Evidence suggests that 4-HNE increases during an ischemia-reperfusion injury in the heart. Apoptosis-inducing factor, mitochondrion-associated 2 (AIFM2) is a mitochondrial located oxidoreductase that participates in caspase-independent apoptosis. In this study, we sought to identify the role of 4-HNE in regulating AIFm2 translocation and cardiomyocyte death during an ischemia-reperfusion injury in the heart. Following ischemia both RNA and protein expression of AIFm2 significantly increased in the ischemic heart compared to sham. Also, 4-HNE adducted AIFm2 translocated from mitochondria to the nucleus shown by western blot analysis in ischemic heart. The mass spectrometric analysis was done to see the modification site on AIFm2 by 4-HNE and revealed that His 174 and Cys 187 are two sites on AIFm2 where 4-HNE adduction occurred. To identify the modification site responsible for AIFm2 translocation we performed site-direct mutagenesis in H9C2 cardiomyocyte, where Histidine 174 was replaced by arginine and Cys 187 was replaced by threonine. When the ischemia-reperfusion injury was induced, only Histidine 174 mutant failed to translocate to the nucleus indicating His 174 modification by 4-HNE was responsible for AIFm2 translocation. To further support the transport mechanism, protein expression of Importin; an adaptor protein responsible for the transfer of proteins to the nucleus was increased in the ischemic heart compared to sham. Collectively, those results for the first time identify the unique role of 4-HNE modification on AIFm2 protein during an ischemia-reperfusion injury in the heart.

Effects of prolonged exposure to hypobaric hypoxia on oxidative stress, inflammation and gluco-insular regulation: the not-so-sweet price for good regulation.

ObjectivesThe mechanisms by which low oxygen availability are associated with the development of insulin resistance remain obscure. We thus investigated the relationship between such gluco-insular derangements in response to sustained (hypobaric) hypoxemia, and changes in biomarkers of oxidative stress, inflammation and counter-regulatory hormone responses.MethodsAfter baseline testing in London (75 m), 24 subjects ascended from Kathmandu (1,300 m) to Everest Base Camp (EBC;5,300 m) over 13 days. Of these, 14 ascended higher, with 8 reaching the summit (8,848 m). Assessments were conducted at baseline, during ascent to EBC, and 1, 6 and 8 week(s) thereafter. Changes in body weight and indices of gluco-insular control were measured (glucose, insulin, C-Peptide, homeostasis model assessment of insulin resistance [HOMA-IR]) along with biomarkers of oxidative stress (4-hydroxy-2-nonenal-HNE), inflammation (Interleukin-6 [IL-6]) and counter-regulatory hormones (glucagon, adrenalin, noradrenalin). In addition, peripheral oxygen saturation (SpO2) and venous blood lactate concentrations were determined.ResultsSpO2 fell significantly from 98.0% at sea level to 82.0% on arrival at 5,300 m. Whilst glucose levels remained stable, insulin and C-Peptide concentrations increased by >200% during the last 2 weeks. Increases in fasting insulin, HOMA-IR and glucagon correlated with increases in markers of oxidative stress (4-HNE) and inflammation (IL-6). Lactate levels progressively increased during ascent and remained significantly elevated until week 8. Subjects lost on average 7.3 kg in body weight.ConclusionsSustained hypoxemia is associated with insulin resistance, whose magnitude correlates with the degree of oxidative stress and inflammation. The role of 4-HNE and IL-6 as key players in modifying the association between sustained hypoxia and insulin resistance merits further investigation.

ALDH2 protects against stroke by clearing 4-HNE

Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme that metabolizes ethanol and toxic aldehydes such as 4-hydroxy-2-nonenal (4-HNE). Using an unbiased proteomic search, we identified ALDH2 deficiency in stroke-prone spontaneously hypertensive rats (SHR-SP) as compared with spontaneously hypertensive rats (SHR). We concluded the causative role of ALDH2 deficiency in neuronal injury as overexpression or activation of ALDH2 conferred neuroprotection by clearing 4-HNE in in vitro studies. Further, ALDH2-knockdown rats revealed the absence of neuroprotective effects of PKCε. Moderate ethanol administration that is known to exert protection against stroke was shown to enhance the detoxification of 4-HNE, and to protect against ischemic cerebral injury through the PKCε-ALDH2 pathway. In SHR-SP, serum 4-HNE level was persistently elevated and correlated inversely with the lifespan. The role of 4-HNE in stroke in humans was also suggested by persistent elevation of its plasma levels for at least 6 months after stroke. Lastly, we observed that 21 of 1 242 subjects followed for 8 years who developed stroke had higher initial plasma 4-HNE levels than those who did not develop stroke. These findings suggest that activation of the ALDH2 pathway may serve as a useful index in the identification of stroke-prone subjects, and the ALDH2 pathway may be a potential target of therapeutic intervention in stroke.

The role of 4-hydroxynonenal in assessment of chronic obstructive pulmonary disease severity

To measure the levels of 4-hydroxynonenal (4-HNE), TNF-α and IL-6 in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and stable COPD, and therefore to explore the role of 4-HNE in the assessment of COPD severity. A total of 242 patients with AECOPD, 182 males and 60 females, age 54 - 89 (mean 72 ± 8) years, 57 outpatients with stable COPD, 55 males and 2 females, age 38 - 76 (mean 60 ± 8) years, and 67 healthy controls, 49 males and 18 females, age 42 - 86 (mean 66 ± 10) years, were included in the study. Based on whether there were respiratory failure, chronic pulmonary heart disease or a history of smoking, the patients with AECOPD were divided into different subgroups. Patients with stable COPD were divided into different subgroups based on lung function or whether there was a history of smoking. The serum 4-HNE, TNF-α and IL-6 concentrations were measured by using enzyme-linked immune sorbent assay (ELISA). The serum 4-HNE levels in patients with AECOPD or stable COPD (16 ± 4) mg/L, (15 ± 5) mg/L were higher than those in healthy controls (12 ± 4) mg/L (both P < 0.01). After control for age, the serum 4-HNE levels in patients with AECOPD were significantly higher than those in stable COPD (F = 7.93, P < 0.01). There were no differences in the serum 4-HNE among AECOPD patients of current smokers, non-smokers and ex-smokers (16 ± 4) mg/L, (17 ± 3) mg/L, (17 ± 4) mg/L. The serum 4-HNE in AECOPD patients with chronic pulmonary heart disease were particularly higher (17 ± 4) mg/L vs (15 ± 4) mg/L (F = 1.23, P < 0.01). There were no differences in the serum 4-HNE between stable COPD patients of current smokers and ex-smokers (14 ± 5) mg/L, (16 ± 4) mg/L (t = -1.44, P > 0.05). In patients with stable COPD, the serum 4-HNE levels were significantly correlated with FEV(1)% (r = -0.345, P < 0.01) and IL-6 (r = 0.363, P < 0.01). The serum levels of 4-HNE in COPD patients with different smoking status were all significantly elevated, particular in patients with acute exacerbation and with pulmonary heart disease. In patients with stable COPD, the 4-HNE levels were negatively correlated with FEV(1)% and positively with serum IL-6 levels. It may be a valuable biomarkers for the assessment of COPD severity.

Lipid peroxidation dysregulation in ischemic stroke: Plasma 4-HNE as a potential biomarker?

4-hydroxynonenal (4-HNE) is a major aldehyde produced during the lipid peroxidation of ω-6 polyunsaturated fatty acids. Recently, 4-HNE has been reported to contribute to the pathogenesis of neuronal diseases such as Alzheimer’s disease. However, the role of 4-HNE in ischemic stroke is unclear yet. In this study, we found that plasma 4-HNE concentrations were higher in the genetic stroke-prone rats (stroke-prone spontaneously hypertensive rats) and experimental stroke rats with middle cerebral artery occlusion (MCAO). Moreover, administration of 4-HNE via intravenous injection before MCAO surgery not only enlarged cerebral ischemia-induced infarct area, but also increased oxidative stress in brain tissue, which was evidenced by the enhanced ROS/MPA levels, and the reduced GSH/GSSG ratio and MnSOD levels. Overexpression of aldehyde dehydrogenasesbcl-2 (ALDH2), an enzyme catalyses 4-HNE, rescued neuronal survival against 4-HNE treatment in PC12 cells. The plasma 4-HNE concentrations in patients with ischemic stroke were higher than those in control subjects. In a small sample population (N=60), the plasma 4-HNE concentration was positively correlated with the plasma homocysteine concentration, a risk factor for ischemic stroke. Taken together, our study suggests that the plasma 4-HNE level is a potential biomarker for ischemic stroke.

Short-term exposure of 4-hydroxynonenal induces mitochondria-mediated apoptosis in PC12 cells

4-Hydroxynonenal (4-HNE) is one of the most reactive aldehydic by-products of lipid peroxidation. The role of 4-HNE in the etiology of various neurodegenerative disorders including cerebral ischemia/reperfusion, Alzheimer's disease, Parkinson's disease, etc. has been documented. We and others have reported that long-term toxic insults of 4-HNE triggers apoptotic signals and oxidative stress in various cells. However, the status of apoptosis following short-term exposure and underlying mechanisms has not been explored so far. We studied the apoptotic changes in PC12 cells receiving short-term exposure of 4-HNE. A significant dose-dependent induction in reactive oxygen species (ROS) and early response markers (c-Fos, c-Jun, and GAP-43) were observed in cells exposed to 4-HNE (10, 25, and 50 µM) for 1h. Following the exposure of PC12 cells to 4-HNE, the levels of protein and messenger RNA expressions of P(53), Bax, and caspase 3 were significantly upregulated, whereas the levels of Bcl(2) was downregulated. We could record the apoptotic signals and ROS generation in PC12 cells receiving 4-HNE exposure for such a short period of time. Induction in the expression and activity of caspase 3 has also indicated the mitochondrial mediation in the apoptosis induction.

Role of the Electrophilic Lipid Peroxidation Product 4-Hydroxynonenal in the Development and Maintenance of Obesity in Mice

The lipid peroxidation product 4-hydroxynonenal (4-HNE) is a signaling mediator with wide-ranging biological effects. In this paper, we report that disruption of mGsta4, a gene encoding the 4-HNE-conjugating enzyme mGSTA4-4, causes increased 4-HNE tissue levels and is accompanied by age-dependent development of obesity which precedes the onset of insulin resistance in 129/sv mice. In contrast, mGsta4 null animals in the C57BL/6 genetic background have normal 4-HNE levels and remain lean, indicating a role of 4-HNE in triggering or maintaining obesity. In mGsta4 null 129/sv mice, the expression of the acetyl-CoA carboxylase (ACC) transcript is enhanced several-fold with a concomitant increase in the tissue level of malonyl-CoA. Also, mitochondrial aconitase is partially inhibited, and tissue citrate levels are increased. Accumulation of citrate could lead to allosteric activation of ACC, further augmenting malonyl-CoA levels. Aconitase may be inhibited by 4-HNE or by peroxynitrite generated by macrophages which are enriched in white adipose tissue of middle-aged mGsta4 null 129/sv mice and, upon lipopolysaccharide stimulation, produce more reactive oxygen species and nitric oxide than macrophages from wild-type mice. Excessive malonyl-CoA synthesized by the more abundant and/or allosterically activated ACC in mGsta4 null mice leads to fat accumulation by the well-known mechanisms of promoting fatty acid synthesis and inhibiting fatty acid beta-oxidation. Our findings complement the recent report that obesity causes both a loss of mGSTA4-4 and an increase in the level of 4-HNE [Grimsrud, P. A., et al. (2007) Mol. Cell. Proteomics 6, 624-637]. The two reciprocal processes are likely to establish a positive feedback loop that would promote and perpetuate the obese state.

Role of 4‐hydroxynonenal in the hemozoin‐mediated inhibition of differentiation of human monocytes to dendritic cells induced by GM‐CSF/IL‐4

In falciparum malaria, rupture of parasitized RBC liberates hemozoin (HZ), polymerized heme that contains and generates lipoperoxidation products. In HZ and HZ-loaded monocytes 4-HNE attained approx. 50 and 15 microM, respectively. In malaria, HZ-loaded monocytes are precursors of dendritic cells (DC). Here, the role of 4-HNE as inhibitor of DC differentiation was examined. 4-HNE in HZ was quantified after derivatization by HPLC. DC were differentiated in vitro from human monocytes supplemented with GM-CSF/IL-4 and analyzed for surface antigens and 4-HNE-adducts by FACScan after labelling with specific antibodies. HZ-loading, or treatment with 4-HNE induced large numbers of 4-HNE-protein-adducts on the monocyte membrane. As low as 10 nM 4-HNE inhibited up-regulation of functionally important DC differentiation markers. 1 microM 4-HNE elicited inhibition of up-regulation of DC differentiation markers as follows: MHC-class I and II, -29% and -40%; CD1a, -16%; CD40, -25%; CD54, -27%; and CD83 (the most important DC differentiation marker), -45%, with no signs of apoptosis. The sequence of additions was important, as the inhibitory effect was reduced when 4-HNE was added after GM-CSF/IL-4, indicating that GM-CSF/IL-4 receptors could be modified by 4-HNE. In conclusion, inhibition of DC differentiation by 4-HNE may play a role in malaria immunodepression.