Acrolein Is a Pathogenic Mediator of Alcoholic Liver Disease and the Scavenger Hydralazine Is Protective in MiceSummary

Background & Aims: Alcoholic liver disease (ALD) remains a major cause of morbidity and mortality, with no Food and Drug Administrationâapproved therapy. Chronic alcohol consumption causes a pro-oxidant environment and increases hepatic lipid peroxidation, with acrolein being the most reactive/toxic by-product. This study investigated the pathogenic role of acrolein in hepatic endoplasmic reticulum (ER) stress, steatosis, and injury in experimental ALD, and tested acrolein elimination/scavenging (using hydralazine) as a potential therapy in ALD. Methods: In vitro (rat hepatoma H4IIEC cells) and in vivo (chronic+binge alcohol feeding in C57Bl/6 mice) models were used to examine alcohol-induced acrolein accumulation and consequent hepatic ER stress, apoptosis, and injury. In addition, the potential protective effects of the acrolein scavenger, hydralazine, were examined both in vitro and in vivo. Results: Alcohol consumption/metabolism resulted in hepatic accumulation of acrolein-protein adducts, by up-regulation of cytochrome P4502E1 and alcohol dehydrogenase, and down-regulation of glutathione-s-transferase-P, which metabolizes/detoxifies acrolein. Alcohol-induced acrolein adduct accumulation led to hepatic ER stress, proapoptotic signaling, steatosis, apoptosis, and liver injury; however, ER-protective/adaptive responses were not induced. Notably, direct exposure to acrolein in vitro mimicked the in vivo effects of alcohol, indicating that acrolein mediates the adverse effects of alcohol. Importantly, hydralazine, a known acrolein scavenger, protected against alcohol-induced ER stress and liver injury, both in vitro and in mice. Conclusions: Our study shows the following: (1) alcohol consumption triggers pathologic ER stress without ER adaptation/protection; (2) alcohol-induced acrolein is a potential therapeutic target and pathogenic mediator of hepatic ER stress, cell death, and injury; and (3) removal/clearance of acrolein by scavengers may have therapeutic potential in ALD. Keywords: Lipid Peroxidation, Apoptosis, Therapeutic, CHO

Histone modifications and alcohol-induced liver disease: Are altered nutrients the missing link?

Alcoholism is a major health problem in the United States and worldwide, and alcohol remains the single most significant cause of liver-related diseases and deaths. Alcohol is known to influence nutritional status at many levels including nutrient intake, absorption, utilization, and excretion, and can lead to many nutritional disturbances and deficiencies. Nutrients can dramatically affect gene expression and alcohol-induced nutrient imbalance may be a major contributor to pathogenic gene expression in alcohol-induced liver disease (ALD). There is growing interest regarding epigenetic changes, including histone modifications that regulate gene expression during disease pathogenesis. Notably, modifications of core histones in the nucleosome regulate chromatin structure and DNA methylation, and control gene transcription. This review highlights the role of nutrient disturbances brought about during alcohol metabolism and their impact on epigenetic histone modifications that may contribute to ALD. The review is focused on four critical metabolites, namely, acetate, S-adenosylmethionine, nicotinamide adenine dinucleotide and zinc that are particularly relevant to alcohol metabolism and ALD

Perturbation of Methionine/S-adenosylmethionine Metabolism as a Novel Vulnerability in MLL Rearranged Leukemia

Leukemias bearing mixed lineage leukemia (MLL) rearrangement (MLL-R) resulting in expression of oncogenic MLL fusion proteins (MLL-FPs) represent an especially aggressive disease subtype with the worst overall prognoses and chemotherapeutic response. MLL-R leukemias are uniquely dependent on the epigenetic function of the H3K79 methyltransferase DOT1L, which is misdirected by MLL-FPs activating gene expression, driving transformation and leukemogenesis. Given the functional necessity of these leukemias to maintain adequate methylation potential allowing aberrant activating histone methylation to proceed, driving leukemic gene expression, we investigated perturbation of methionine (Met)/S-adenosylmethionine (SAM) metabolism as a novel therapeutic paradigm for MLL-R leukemia. Disruption of Met/SAM metabolism, by either methionine deprivation or pharmacologic inhibition of downstream metabolism, reduced overall cellular methylation potential, reduced relative cell numbers, and induced apoptosis selectively in established MLL-AF4 cell lines or MLL-AF6-expressing patient blasts but not in BCR-ABL-driven K562 cells. Global histone methylation dynamics were altered, with a profound loss of requisite H3K79 methylation, indicating inhibition of DOT1L function. Relative occupancy of the repressive H3K27me3 modification was increased at the DOT1L promoter in MLL-R cells, and DOT1L mRNA and protein expression was reduced. Finally, pharmacologic inhibition of Met/SAM metabolism significantly prolonged survival in an advanced, clinically relevant patient–derived MLL-R leukemia xenograft model, in combination with cytotoxic induction chemotherapy. Our findings provide support for further investigation into the development of highly specific allosteric inhibitors of enzymatic mediators of Met/SAM metabolism or dietary manipulation of methionine levels. Such inhibitors may lead to enhanced treatment outcomes for MLL-R leukemia, along with cytotoxic chemotherapy or DOT1L inhibitors

Increased levels of Osteopontin are associated with dementia in the presence of cerebral small vessel disease

Abstract Background Osteopontin is a proinflammatory cytokine associated with systemic vascular, inflammatory, and autoimmune diseases. It has been recently implicated in neuroinflammation and neurodegeneration. We hypothesized that plasma osteopontin is a deleterious neuroinflammatory marker increased in people with dementia and cerebral small vessel disease (CSVD). Method We conducted a pilot study in participants in the longitudinal multi‐ethnic Northern Manhattan Study (NOMAS). Three groups were selected based on their dementia status and evidence of subclinical CSVD, and chosen to be similar in age, sex, and education attainment: No Dementia/No CSVD (n = 19), Dementia/No CSVD (n = 22), and Dementia+CSVD (n = 21). Dementia (any type) was diagnosed by consensus adjudication following a series of comprehensive neuropsychological assessments and a review of medical history. CSVD was indicated by silent brain infarcts, perivascular spaces, cerebral microbleeds, and white matter hyperintensity volumes on MRI. Osteopontin was measured by quantitative solid‐phase ELISA. Multinomial logistic regression was used to examine the difference in osteopontin levels across groups, adjusting for key determinants of CSVD and neurodegeneration in NOMAS, including age, race/ethnicity, BMI, and brain volume. Result Osteopontin levels were substantially elevated in the Dementia+ CSVD group (mean = 70.69±39.00 ng/ml) and only slightly increased in the Dementia/No CSVD group (mean = 45.46±19.11) compared to the No dementia/No CSVD group (mean = 36.43±15.72). Osteopontin was associated with dementia+CSVD (Odds Ratio (OR) per ng/ml = 1.06, 95%CI 1.02‐1.11) in unadjusted analysis, and this remained consistent and significant after adjusting for covariates, including brain volume. Osteopontin was strongly correlated with WMHV (Pearson r = 0.46, p = 0.0001), but not with other components of CSVD. Conclusion In this pilot study, we observed a significant relationship between increased levels of osteopontin and dementia. This link is predominately driven by vascular contributions to dementia through the presence of CSVD, specifically through the burden of white matter lesions on MRI. Brain volume, a marker of neurodegeneration, does not seem to influence this relationship. Our study provides further evidence to suggest that underlying white matter disease and CSVD are likely targets of deleterious osteopontin expression in dementia

Osteopontin is associated with dementia in the presence of cerebral small vessel disease

Background: Osteopontin (OPN) is a proinflammatory cytokine that has been recently implicated in neuroinflammation and neurodegeneration. We hypothesized that an increase in plasma osteopontin is a deleterious neuroinflammatory marker in people with dementia and cerebral small vessel disease (CSVD).Methods: A pilot study was conducted on participants in the Northern Manhattan Study (NOMAS). Three groups were selected based on their dementia status and evidence of subclinical CSVD and chosen to be similar in age, sex, and education attainment: No dementia/No CSVD (n=19), Dementia/No CSVD (n=22), and Dementia+CSVD (n=21). Dementia (any type) was diagnosed by consensus adjudication following a series of comprehensive neuropsychological assessments and a review of the medical history. CSVD was indicated by silent brain infarcts, enlarged perivascular spaces, cerebral microbleeds, and white matter hyperintensity volumes (WMHV) on MRI. Multinomial logistic regression was used to examine the difference in OPN levels across groups, adjusting for key determinants of CSVD and neurodegeneration. Results: Plasma osteopontin levels were elevated in the Dementia+CSVD group (mean=70.69 & PLUSMN;39.00 ng/ml) but not in the Dementia/No CSVD group (mean=45.46 & PLUSMN;19.11 ng/ml) compared to the No dementia/No CSVD group (mean=36.43 & PLUSMN;15.72 ng/ml). Osteopontin was associated with Dementia+CSVD (Odds Ratio (OR) per ng/ml=1.06, 95%CI 1.02-1.11) after adjusting for covariates, including brain volume. OPN was strongly correlated with WMHV (Spearman's rank correlation =0.46, p=0.0001), but not with other components of CSVD. Conclusion: In this pilot, greater levels of plasma osteopontin were associated with dementia with evidence of CSVD. This link was predominately driven by the contribution of OPN to dementia through the burden of white matter lesions

S-Adenosylmethionine Decreases Lipopolysaccharide-Induced Phosphodiesterase 4B2 and Attenuates Tumor Necrosis Factor Expression via cAMP/Protein Kinase A PathwayS⃞

S-Adenosylmethionine (SAM) treatment has anti-inflammatory, cytoprotective effects against endotoxin-induced organ injury. An important component of the anti-inflammatory action of SAM involves down-regulation of the lipopolysaccharide (LPS)-induced transcriptional induction of tumor necrosis factor-α (TNF) expression by monocytes/macrophages. We examined the effect of SAM on expression and activity of LPS-induced up-regulation of phosphodiesterase 4 (PDE4), which regulates cellular cAMP levels and TNF expression. LPS treatment of RAW 264.7, a mouse macrophage cell line, led to the induction of Pde4b2 mRNA expression with no effect on Pde4a or Pde4d. SAM pretreatment led to a significant decrease in LPS-induced up-regulation of Pde4b2 expression in both RAW 264.7 cells and primary human CD14+ monocytes. Of note, the decreased Pde4b2 mRNA expression correlated with the SAM-dependent increase in the transcriptionally repressive histone H3 lysine 9 trimethylation on the Pde4b2 intronic promoter region. The SAM-mediated decrease in LPS-inducible Pde4b2 up-regulation resulted in an increase in cellular cAMP levels and activation of cAMP-dependent protein kinase A (PKA), which plays an inhibitory role in LPS-induced TNF production. In addition, SAM did not affect LPS-inducible inhibitor of nuclear factor-κB degradation or nuclear factor-κB (NF-κB)-p65 translocation into the nucleus but rather inhibited NF-κB transcriptional activity. These results demonstrate for the first time that inhibition of LPS-induced PDE4B2 up-regulation and increased cAMP-dependent PKA activation are significant mechanisms contributing to the anti-TNF effect of SAM. Moreover, these data also suggest that SAM may be used as an effective PDE4B inhibitor in the treatment of chronic inflammatory disorders in which TNF expression plays a significant pathogenic role