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The growth differentiation factor 11 (GDF11), a member of the superfamily of the transforming growth factor β, has gained relevance in the last few years due to its remarkable effects in cellular biology, particularly in the nervous system, skeletal muscle, the heart, and many epithelial tissues. Some controversies have been raised about this growth factor. Many of them have been related to technical factors but also the nature of the cellular target. In liver biology and pathobiology, the GDF11 has shown to be related in many molecular aspects, with a significant impact on the physiology and the initiation and progression of the natural history of liver diseases. GDF11 has been involved as a critical regulator in lipid homeostasis, which, as it is well known, is the first step in the progression of liver disease. However, also it has been reported that the GDF11 is involved in fibrosis, senescence, and cancer. Although there are some controversies, much of the literature indicates that GDF11 displays effects tending to solve or mitigate pathological states of the liver, with reasonable evidence of correlation with other organs or systems. To a large extent, the controversy, as mentioned, is due to technical problems, such as the specificity of GDF11 antibodies, confusion with its closer family member, myostatin, and the state of differentiation in the tissues. In the present work, we reviewed the specific effects of GDF11 in the biology and pathobiology of the liver as a potential and promising factor for therapeutic intervention shortly.

Hepatocellular carcinoma (HCC) accounts for 85% of primary liver cancer, the third most common cause of cancer-related deaths worldwide. Its incidence has been increasing in both men and women. In Western countries, high-calorie diets, mainly rich in carbohydrates such as fructose, represent a significant concern due to their repercussions on the population’s health. A high-fructose diet is related to the development of Metabolic-Associated Fatty Liver Disease (MAFLD), formerly named Non-Alcoholic Fatty Liver Disease (NAFLD), and the progression of HCC as it potentiates the lipogenic pathway and the accumulation of lipids. However, fructose metabolism seems to be different between the stages of the disease, carrying out a metabolic reprogramming to favor the proliferation, inflammation, and metastatic properties of cancer cells in HCC. This review focuses on a better understanding of fructose metabolism in both scenarios: MAFLD and HCC.

Cadmium is a toxic element to which man can be exposed at work or in the environment. Cd's most salient toxicological property is its exceptionally long half-life in the human body. Once absorbed, Cd accumulates in the human body, particularly in the liver. The cellular actions of Cd are extensively documented, but the molecular mechanisms underlying these actions are still not resolved. The liver manages the cadmium to eliminate it by a diverse mechanism of action. Still, many cellular and physiological responses are executed in the task, leading to worse liver damage, ranging from steatosis, steatohepatitis, and eventually hepatocellular carcinoma. The progression of cadmium-induced liver damage is complex, and it is well-known the cellular response that depends on the time in which the metal is present, ranging from oxidative stress, apoptosis, adipogenesis, and failures in autophagy. In the present work, we aim to present a review of the current knowledge of cadmium toxicity and the cellular response in the liver.

Non-alcoholic fatty liver disease (NAFLD) and progression to non-alcoholic steatohepatitis (NASH) result as a consequence of diverse conditions, mainly unbalanced diets. Particularly, high-fat and cholesterol content, as well as carbohydrates, such as those commonly ingested in Western countries, frequently drive adverse metabolic alterations in the liver and promote NAFLD development. Lipid liver overload is also one of the main risk factors for initiation and progression of hepatocellular carcinoma (HCC), but detailed knowledge on the relevance of high nutritional cholesterol remains elusive. We were aimed to characterize HCC development in mice fed with a Western diet (high in lipids and cholesterol) and to identify molecular alterations that define a subtype of liver cancer induced by lipid overload. Mice under western or high cholesterol diets more frequently developed tumors with a more aggressive phenotype than animals fed with a chow diet. Associated changes involved macrophage infiltration, angiogenesis, and stemness features. RNA-seq revealed a specific gene expression signature (Slc41a, Fabp5, Igdcc4 and Mthfd1l) resembling the adverse phenotypic features and poor clinical outcomes seen in patients with HCC. In conclusion, consumption of lipid enriched diets, particularly cholesterol, could accelerate HCC development with an aggressive phenotype and poor prognosis

Growth differentiation factor 11 (GDF11) has been characterized as a key regulator of differentiation in cells that retain stemness features. Recently, it has been reported that GDF11 exerts tumor‐suppressive properties in hepatocellular carcinoma cells, decreasing clonogenicity, proliferation, spheroid formation, and cellular function, all associated with a decrement in stemness features, resulting in mesenchymal to epithelial transition and loss of aggressiveness. The aim of the present work was to investigate the mechanism associated with the tumor‐suppressive properties displayed by GDF11 in liver cancer cells. Hepatocellular carcinoma‐derived cell lines were exposed to GDF11 (50 ng/ml), RNA‐seq analysis in Huh7 cell line revealed that GDF11 exerted profound transcriptomic impact, which involved regulation of cholesterol metabolic process, steroid metabolic process as well as key signaling pathways, resembling endoplasmic reticulum‐related functions. Cholesterol and triglycerides determination in Huh7 and Hep3B cells treated with GDF11 exhibited a significant decrement in the content of these lipids. The mTOR signaling pathway was downregulated, and this was associated with a reduction in key proteins involved in the mevalonate pathway. In addition, real‐time metabolism assessed by Seahorse technology showed abridged glycolysis as well as glycolytic capacity, closely related to an impaired oxygen consumption rate and decrement in adenosine triphosphate production. Finally, transmission electron microscopy revealed mitochondrial abnormalities, such as cristae disarrangement, consistent with metabolic changes. Results provide evidence that GDF11 impairs cancer cell metabolism targeting lipid homeostasis, glycolysis, and mitochondria function and morphology., This study was partially funded by a grant from the Consejo Nacionalde Ciencia y Tecnología (CONACYT): CB252942, Fronteras de laCiencia1320, Apoyo al Fortalecimiento y Desarrollo de la Infra-estructura 2013205941 and 2017280788, and Universidad Autonoma Metropolitana. We thank the confocal core unit of the Universidad Autonoma Metropolitana Iztapalapa. SH, MGR, ASN arescholarship holders from Conacyt. We acknowledge the support fromgrants: PID2019111669RB, and SAF201785877R from PlanNacional de IþD, Spain, and by the CIBEREHD; the center grantP50AA011999 Southern California Research Center for ALPD andCirrhosis funded by the National Institute on Alcohol Abuse andAlcoholism/National Institutes of Health (NIH); as well as supportfrom AGAUR of the Generalitat de Catalunya SGR20171112,European Cooperation in Science & Technology (COST) ACTIONCA17112 Prospective European DrugInduced Liver Injury Network,and the Fundación BBVA. RED Nacional 2018102799Tdeenfermedades metabólicas y Cáncer y Proyecto 201916/31 DeFundacion Marató TV3

Hepatocyte growth factor (HGF) has been proved to protect the liver against α-naphthylisothiocyanate (ANIT)-induced cholestasis by acting as an antioxidant agent and redirecting toxic biliary solutes towards blood for urinary excretion. However, this may represent an additional potential risk for kidney integrity, which is already compromised by the cholestatic process itself (cholemic nephropathy). Therefore, in the present work, we studied the renal damage caused by ANIT-induced cholestasis and whether it is aggravated or, on the contrary, counteracted by HGF; if the latter holds, the involvement of its antioxidant properties will be ascertained. ANIT-induced cholestatic deleterious renal effects were corroborated by the presence of urine bile salts, impairment of renal function, and the alterations of renal damage markers, such as HSP72, creatinine clearance, and albuminuria. HGF fully reverted all these, and the cast formation in the tubules was significantly decreased. These findings were associated with the control of renal oxidative stress. In summary, despite HGF enhancing the overload of potentially harmful biliary constituents that the kidney should remove from the bloodstream as an alternative depuration organ in cholestasis, it simultaneously protects the kidney from this damage by counteracting the prooxidant effects resulting from this harmful exposure.

Non-alcoholic fatty liver disease (NAFLD) encompasses a broad spectrum of histopathological changes ranging from non-inflammatory intracellular fat deposition to non-alcoholic steatohepatitis (NASH), which may progress into hepatic fibrosis, cirrhosis, or hepatocellular carcinoma. Recent data suggest that impaired hepatic cholesterol homeostasis and its accumulation are relevant to the pathogenesis of NAFLD/NASH. Despite a vital physiological function of cholesterol, mitochondrial dysfunction is an important consequence of dietary-induced hypercholesterolemia and was, subsequently, linked to many pathophysiological conditions. The aim in the current study was to evaluate the morphological and molecular changes of cholesterol overload in mouse liver and particularly, in mitochondria, induced by a high-cholesterol (HC) diet for one month. Histopathological studies revealed microvesicular hepatic steatosis and significantly elevated levels of liver cholesterol and triglycerides leading to impaired liver synthesis. Further, high levels of oxidative stress could be determined in liver tissue as well as primary hepatocyte culture. Transcriptomic changes induced by the HC diet involved disruption in key pathways related to cell death and oxidative stress as well as upregulation of genes related to glutathione homeostasis. Impaired liver function could be associated with a decrease in mitochondrial membrane potential and ATP content and significant alterations in mitochondrial dynamics. We demonstrate that cholesterol overload in the liver leads to mitochondrial changes which may render damaged hepatocytes proliferative and resistant to cell death whereby perpetuating liver damage.

Cholestasis is a clinical syndrome common to a large number of hepatopathies, in which either bile production or its transit through the biliary tract is impaired due to functional or obstructive causes; the consequent intracellular retention of toxic biliary constituents generates parenchyma damage, largely via oxidative stress-mediated mechanisms. Hepatocyte growth factor (HGF) and its receptor c-Met represent one of the main systems for liver repair damage and defense against hepatotoxic factors, leading to an antioxidant and repair response. In this study, we evaluated the capability of HGF to counteract the damage caused by the model cholestatic agent, α-naphthyl isothiocyanate (ANIT). HGF had clear anti-cholestatic effects, as apparent from the improvement in both bile flow and liver function test. Histology examination revealed a significant reduction of injured areas. HGF also preserved the tight-junctional structure. These anticholestatic effects were associated with the induction of basolateral efflux ABC transporters, which facilitates extrusion of toxic biliary compounds and its further alternative depuration via urine. The biliary epithelium seems to have been also preserved, as suggested by normalization in serum GGT levels, CFTR expression and cholangyocyte primary cilium structure our results clearly show for the first time that HGF protects the liver from a cholestatic injury.

Introduction and objectives It is well-known that signaling mediated by the hepatocyte growth factor (HGF) and its receptor c-Met in the liver is involved in the control of cellular redox status and oxidative stress, particularly through its ability to induce hepatoprotective gene expression by activating survival pathways in hepatocytes. It has been reported that HGF can regulate the expression of some members of the NADPH oxidase family in liver cells, particularly the catalytic subunits and p22phox. In the present work we were focused to characterize the mechanism of regulation of p22phox by HGF and its receptor c-Met in primary mouse hepatocytes as a key determinant for cellular redox regulation. Materials and methods Primary mouse hepatocytes were treated with HGF (50 ng/mL) at different times. cyba expression (gene encoding p22phox) or protein content were addressed by real time RT-PCR, Western blot or immunofluorescence. Protein interactions were explored by immunoprecipitation and FRET analysis. Results Our results provided mechanistic information supporting the transcriptional repression of cyba induced by HGF in a mechanism dependent of NF-κB activity. We identified a post-translational regulation mechanism directed by p22phox degradation by proteasome 26S, and a second mechanism mediated by p22phox sequestration by c-Met in plasma membrane. Conclusion Our data clearly show that HGF/c-Met exerts regulation of the NADPH oxidase by a wide-range of molecular mechanisms. NADPH oxidase-derived reactive oxygen species regulated by HGF/c-Met represents one of the main mechanisms of signal transduction elicited by this growth factor.

Tuberculosis (TB) is one of the deadliest infectious diseases in humankind history. Although, drug sensible TB is slowly decreasing, at present the rise of TB cases produced by multidrug-resistant (MDR) and extensively drug-resistant strains is a big challenge. Thus, looking for new therapeutic options against these MDR strains is mandatory. In the present work, we studied, in BALB/c mice infected with MDR strain, the therapeutic effect of supra-pharmacological doses of the conventional primary antibiotics rifampicin and isoniazid (administrated by gavage or intratracheal routes), in combination with recombinant human hepatocyte growth factor (HGF). This high dose of antibiotics administered for 3 months, overcome the resistant threshold of the MDR strain producing a significant reduction of pulmonary bacillary loads but induced liver damage, which was totally prevented by the administration of HGF. To address the long-term efficiency of this combined treatment, groups of animals after 1 month of treatment termination were immunosuppressed by glucocorticoid administration and, after 1 month, mice were euthanized, and the bacillary load was determined in lungs. In comparison with animals treated only with a high dose of antibiotics, animals that received the combined treatment showed significantly lower bacterial burdens. Thus, treatment of MDR-TB with very high doses of primary antibiotics particularly administrated by aerial route can produce a very good therapeutic effect, and its hepatic toxicity can be prevented by the administration of HGF, becoming in a new treatment modality for MDR-TB.

Cholesterol overload in the liver has shown toxic effects by inducing the aggravation of nonalcoholic fatty liver disease to steatohepatitis and sensitizing to damage. Although the mechanism of damage is complex, it has been demonstrated that oxidative stress plays a prominent role in the process. In addition, we have proved that hepatocyte growth factor induces an antioxidant response in hepatic cells; in the present work we aimed to figure out the protective effect of this growth factor in hepatocytes overloaded with free cholesterol. Hepatocytes from mice fed with a high-cholesterol diet were treated or not with HGF, reactive oxygen species present in cholesterol overloaded hepatocytes significantly decreased, and this effect was particularly associated with the increase in glutathione and related enzymes, such asγ-gamma glutamyl cysteine synthetase, GSH peroxidase, and GSH-S-transferase. Our data clearly indicate that HGF displays an antioxidant response by inducing the glutathione-related protection system.

While combined antiretroviral therapy (cART) has had a great impact on the treatment of HIV-1 infection, the persistence of long-lived cells with an intact provirus precludes virus eradication and sterilizing cure. CRISPR/Cas9 genome editing has become an efficient tool to eradicate HIV-1 genome or prevent replication. Furthermore, regulation of Cas9 gene expression by HIV can induce mutations that could inactivate the proviral genome, making a gene therapy safe by preventing the induction of non-specific mutations, which could compromise the integrity of healthy cells. In this study, isolated HIV-1 LTR, INS and RRE sequences were used to regulate Cas9 expression in HEK293 cells, and guide RNAs (gRNAs) were designed to target mutations in HIV-1 conserved regions such as tat and rev regulatory genes. We demonstrate that Cas9 expression in our system is controlled by the HIV-1 Tat and Rev proteins, leading to self-regulation of gene edition, and showing a strong antiviral effect by inactivating HIV-1 replication. Sequencing analysis confirmed that viral genome was partially excised by multiplex editing (90% efficiency), and viral capsid protein (CA-p24) was undetectable. In conclusion, the self-regulated CRISPR/Cas9 system may be a reliable and accurate strategy for eliminating HIV-1 infection whose effect will be restricted to infected cells.

Metabolic factors are the major risk of non-alcoholic fatty liver disease, although other factors may contribute steatosis. Cadmium exposure produces histopathological and molecular changes in liver, which are consistent with steatosis. In the present study, we describe the effect of low cadmium acute treatment on hepatocytes obtained from mice fed with a high cholesterol diet. Our data suggest that hepatocytes with cholesterol overload promote an adaptive response against cadmium-induced acute toxicity by up-regulating anti-apoptotic proteins, managing ROS overproduction, increasing GSH synthesis and MT-II content to avoid protein oxidation. Cadmium treatment increases lipid content in cholesterol-fed mice hepatocytes because of an impaired autophagy process. Our data suggest an essential function of macroautophagy in the regulation of lipid storage induced by Cd on hepatocytes, that implies that alterations in this pathway may be a mechanism that aggravates hepatic steatosis.

Little is known of how the stress response varies when animals confront seasonal life-history processes. Antioxidant defenses and damage caused by oxidative stress and their link with immunocompetence are powerful biomarkers to assess animal´s physiological stress response. The aim of this study was A) to determine redox state and variation in basal (pre-acute stress) immune function during summer, autumn and winter (spring was not assessed due to restrictions in collecting permit) in the fish-eating Myotis (Myotis vivesi; Chiroptera), and B) to determine the effect of acute stress on immunocompetence and redox state during each season. Acute stress was stimulated by restricting animal movement for 6 and 12 h. The magnitude of the cellular immune response was higher during winter whilst that of the humoral response was at its highest during summer. Humoral response increased after 6 h of movement restriction stress and returned to baseline levels after 12 h. Basal redox state was maintained throughout the year, with no significant changes in protein damage, and antioxidant activity was modulated mainly in relation to variation to environment cues, increasing during high temperatures and decreasing during windy nights. Antioxidant activity increased after the 6 h of stressful stimuli especially during summer and autumn, and to a lesser extent in early winter, but redox state did not vary. However, protein damage increased after 12 h of stress during summer. Prolonged stress when the bat is engaged in activities of high energy demand overcame its capacity to maintain homeostasis resulting in oxidative damage.

In a previous work we detected an important increase in reactive oxygen species (ROS) concentrations during idiophase in lovastatin fermentations. Hence, the objective of the present work was to determine if ROS contributes to the regulation of lovastatin biosynthesis. Exogenous antioxidants were used to reduce ROS accumulation. The addition of N-Acetyl-L-cysteine (NAC) decreased ROS accumulation and concurrent lovastatin production. In solid-state fermentation (SSF), the addition of 100 mM of NAC lowered ROS accumulation by 53 %, together with a 79 % decrease in lovastatin biosynthesis. A similarly, situation was observed in submerged fermentation (SmF). Decreased lovastatin production was due to a lower expression of the regulatory gene lovE , and gene lovF . Moreover, the addition of H 2 O 2 to the culture caused precocious gene expression and lovastatin biosynthesis. These results indicate that ROS accumulation in idiophase contributes to the regulation of the biosynthetic genes. It was considered that Yap1 (Atyap1) could be a transcription factor linking ROS with lovastatin biosynthesis. In a Northern analysis, Aspergillus terreus yap1 gene (At yap1 ) was highly expressed during trophophase but down regulated during idiophase. Conversely, expression pattern of srrA gene, suggested that SrrA could positively control lovastatin biosynthesis, and also explaining the characteristics of the biosynthesis in SSF.

Acute pancreatitis is a multifactorial disease associated with profound changes of the pancreas induced by release of digestive enzymes that lead to increase in proinflammatory cytokine production, excessive tissue necrosis, edema, and bleeding. Elevated levels of hepatocyte growth factor (HGF) and its receptor c-Met have been observed in different chronic and acute pancreatic diseases including experimental models of acute pancreatitis. In the present study, we investigated the protective effects induced by the recombinant human HGF in a mouse model of cerulein-induced acute pancreatitis. Pancreatitis was induced by 8 hourly administrations of supramaximal cerulein injections (50 µg/kg, ip). HGF treatment (20 µg/kg, iv), significantly attenuated lipase content and amylase activity in serum as well as the degree inflammation and edema overall leading to less severe histologic changes such as necrosis, induced by cerulein. Protective effects of HGF were associated with activation of pro-survival pathways such as Akt, Erk1/2, and Nrf2 and increase in executor survival-related proteins and decrease in pro-apoptotic proteins. In addition, ROS content and lipid peroxidation were diminished, and glutathione synthesis increased in pancreas. Systemic protection was observed by lung histology. In conclusion, our data indicate that HGF exerts an Nrf2 and glutathione-mediated protective effect on acute pancreatitis reflected by a reduction in inflammation, edema, and oxidative stress.

Primary liver cancers represent the second leading cause of cancer-related deaths worldwide. Diverse etiological factors include chronic viral hepatitis, aflatoxin and alcohol exposure as well as aberrant liver lipid overload. Cholesterol has been identified as a key inducer of metabolic impairment, oxidative stress and promoter of cellular dysfunction. The aim of this work was to address the oxidative stress-mediated DNA damage induced by cholesterol overload, and its role in the development of hepatocellular carcinoma. C57BL/6 male mice were fed with a high cholesterol diet, followed by a single dose of N-diethylnitrosamine (DEN, 10 μg/g, ip). Reactive oxygen species generation, DNA oxidation, antioxidant and DNA repair proteins were analyzed at different time points. Diet-induced cholesterol overload caused enhanced oxidative DNA damage in the liver and was associated with a decrease in key DNA repair genes as early as 7 days. Interestingly, we found a cell survival response, induced by cholesterol, judged by a decrement in Bax to Bcl2 ratio. Importantly, N-acetyl-cysteine supplementation significantly prevented DNA oxidation damage. Furthermore, at 8 months after DEN administration, tumor growth was significantly enhanced in mice under cholesterol diet in comparison to control animals. Together, these results suggest that cholesterol overload exerts an oxidative stress-mediated effects and promotes the development of liver cancer.

Nonalcoholic steatohepatitis is one of the leading causes of liver disease. Dietary factors determine the clinical presentation of steatohepatitis and can influence the progression of related diseases. Cholesterol has emerged as a critical player in the disease and hence consumption of cholesterol-enriched diets can lead to a progressive form of the disease. The aim was to investigate the impact of liver cholesterol overload on the progression of the obstructive cholestasis in mice subjected to bile duct ligation surgery. Mice were fed with a high cholesterol diet for two days and then were subjected to surgery procedure; histological, biochemical, and molecular analyses were conducted to address the effect of cholesterol in liver damage. Mice under the diet were more susceptible to damage. Results show that cholesterol fed mice exhibited increased apoptosis and oxidative stress as well as reduction in cell proliferation. Mortality following surgery was higher in HC fed mice. Liver cholesterol impairs the repair of liver during obstructive cholestasis and aggravates the disease with early fatal consequences; these effects were strongly associated with oxidative stress., This work was supported by grants of the CONACYT 252942, 236558, and 166042, CONACYT Fronteras de la Ciencia 1320, Asociación Mexicana de Hepatología, and SEP-PRODEP-913026-1461211, Universidad Autónoma Metropolitana Iztapalapa, by grants SAF-2011-23031 and SAF-2012-34831 from Plan Nacional de I+D, Spain, Fundació la Marató de TV3, La Mutua Madrileña, PI11/0325 (META) Grant from the Instituto Salud Carlos III, by the support of CIBEREHD, and by the Center Grant P50-AA-11999 from Research Center for Liver and Pancreatic Diseases funded by NIAAA/NIH.

Obesity and alcohol consumption are risk factors for hepatic steatosis, and both commonly coexist. Our objective was to evaluate the effect of ethanol and acetaldehyde on primary hepatocytes obtained from mice fed for two days with a high cholesterol (HC) diet. HC hepatocytes increased lipid and cholesterol content. HC diet sensitized hepatocytes to the toxic effect of ethanol and acetaldehyde. Cyp2E1 content increased with HC diet, as well as in those treated with ethanol or acetaldehyde, while the activity of this enzyme determined in microsomes increased in the HC and in all ethanol treated hepatocytes, HC and CW. Oxidized proteins were increased in the HC cultures treated or not with the toxins. Transmission electron microscopy showed endoplasmic reticulum (ER) stress and megamitochondria in hepatocytes treated with ethanol as in HC and the ethanol HC treated hepatocytes. ER stress determined by PERK content was increased in ethanol treated hepatocytes from HC mice and CW. Nuclear translocation of ATF6 was observed in HC hepatocytes treated with ethanol, results that indicate that lipids overload and ethanol treatment favor ER stress. Oxidative stress, ER stress, and mitochondrial damage underlie potential mechanisms for increased damage in steatotic hepatocyte treated with ethanol.

Statins are a group of extremely successful drugs that lower cholesterol levels in blood; decreasing the risk of heath attack or stroke. In recent years, statins have also been reported to have other biological activities and numerous potential therapeutic uses. Natural statins are lovastatin and compactin, while pravastatin is derived from the latter by biotransformation. Simvastatin, the second leading statin in the market, is a lovastatin semisynthetic derivative. Lovastatin is mainly produced by Aspergillus terreus strains, and compactin by Penicillium citrinum. Lovastatin and compactin are produced industrially by liquid submerged fermentation, but can also be produced by the emerging technology of solid-state fermentation, that displays some advantages. Advances in the biochemistry and genetics of lovastatin have allowed the development of new methods for the production of simvastatin. This lovastatin derivative can be efficiently synthesized from monacolin J (lovastatin without the side chain) by a process that uses the Aspergillus terreus enzyme acyltransferase LovD. In a different approach, A. terreus was engineered, using combinational biosynthesis on gene lovF, so that the resulting hybrid polyketide synthase is able to in vivo synthesize 2,2-dimethylbutyrate (the side chain of simvastatin). The resulting transformant strains can produce simvastatin (instead of lovastatin) by direct fermentation.

In recent years, there has been a growing interest to explore the responsiveness to injury in steatotic hepatocyte. VL-17A cells, which express ADH and Cyp2E1 overloaded with free fatty acids (1 mM of oleic and palmitic acid 2:1) showed an increased oxidative damaged after 24 h free fatty acids treatment when exposed to ethanol (100 mM) for 48 h as a second injury. An increment in reactive oxygen species, determined by DCFH-DA, protein oxidation, and apoptosis were observed although an increase in main antioxidant proteins such as superoxide dismutase 1 and glutathione peroxidase were observed, but failed in gamma-glutamylcysteine synthetase, suggesting a decreased capacity of synthesis of glutathione compared with cells treated only with free fatty acids or ethanol. The increased oxidative stress and toxicity in lipid overloaded VL-17A cells subjected to ethanol exposure were accompanied by increases in Cyp2E1 protein expression. Our data show that lipid loaded in an in vitro model, VL-17A cells, is more susceptible to cell damage and oxidative stress when treated with ethanol.

Alcohol is undoubtedly, the main toxic agent that people consume by recreation and the abuse is associated with liver damage, mainly by the overproduction of reactive oxygen species and the toxic effects of its first metabolite acetaldehyde. It is known that acetaldehyde targets mitochondria inducing redox imbalance and oxidative stress. Mitochondrial superoxide dismutase transforms superoxide radical into hydrogen peroxide, which in addition, is transformed in water by other enzymes. In the present study we demonstrate that acetaldehyde transiently impairs SOD2 activity in HepG2 cells, the decrease in the enzyme activity was associated to a reduction in the protein content, which was rapidly recovered, to basal values, by synthesis de novo in a mechanism mediated by NF-κB and PKC. The SOD2 impairment was not associated with adduct formation. The recovery on SOD2 activity in HepG2 cells can represent survival advantage for cancer cells, the results shown that SOD2 could be considered a therapeutic target in liver cancer.

The present work was focused on finding a relationship between reactive oxygen species (ROS) and lovastatin biosynthesis (secondary metabolism) in Aspergillus terreus. In addition, an effort was made to find differences in accumulation and control of ROS in submerged (SmF) and solid-state fermentation (SSF), which could help explain higher metabolite production in the latter. sod1 expression, ROS content, and redox balance kinetics were measured during SmF and SSF. Results showed that A. terreus sod1 gene (oxidative stress defence enzyme) was intensely expressed during rapid growth phase (trophophase) of lovastatin fermentations. This high expression decreased abruptly, just before the onset of production (idiophase). However, ROS measurements detected high concentrations only in idiophase, suggesting a link between ROS and lovastatin biosynthesis. Apparently sod1 down regulation promotes the rise of ROS during idiophase. This oxidative state in idiophase was further supported by a high redox balance observed in trophophase that changed to a low value in idiophase (around six-fold lower). The patterns of ROS accumulation, sod1 expression, and redox balance behaviour were similar in SmF and SSF. However, sod1 expression and ROS concentration (ten-fold), were higher in SmF. Our results indicate a link between ROS and lovastatin biosynthesis. Also, showed differences of physiology in SSF that yield lower but more steady ROS concentrations, which could be associated to higher lovastatin production.