Herminia G. Martínez-Rodríguez

Acetylsalicylic acid inhibits hepatitis C virus RNA and protein expression through cyclooxygenase 2 signaling pathways

It has been reported that salicylates (sodium salicylate and aspirin) inhibit the replication of flaviviruses, such as Japanese encephalitis virus and dengue virus. Therefore, we considered it important to test whether acetylsalicylic acid (ASA) had anti–hepatitis C virus (HCV) activity. To this end, we examined the effects of ASA on viral replication and protein expression, using an HCV subgenomic replicon cell culture system. We incubated Huh7 replicon cells with 2‐8 mM ASA for different times and measured HCV‐RNA and protein levels by northern blot, real‐time polymerase chain reaction, and western analysis, respectively. We found that ASA had a suppressive effect on HCV‐RNA and protein levels (nearly 58%). ASA‐dependent inhibition of HCV expression was not mediated by the 5′‐internal ribosome entry site or 3′‐untranslated regions, as determined by transfection assays using bicistronic constructs containing these regulatory regions. However, we found that HCV‐induced cyclooxygenase 2 (COX‐2) messenger RNA and protein levels and activity and these effects were down‐regulated by ASA, possibly by a nuclear factor kappa B–independent mechanism. We also observed that the ASA‐dependent inhibition of viral replication was due in part to inhibition of COX‐2 and activation of p38 and mitogen‐activated protein kinase/extracellular signal‐regulated kinase kinase 1/2 (MEK1/2) mitogen‐activated protein kinases (MAPKs). Inhibition of these kinases by SB203580 and U0126, respectively, and by short interfering RNA silencing of p38 and MEK1 MAPK prevented the antiviral effect of ASA. Taken together, our findings suggest that the anti‐HCV effect of ASA in the Huh7 replicon cells is due to its inhibitory effect on COX‐2 expression, which is mediated in part by the activation of MEK1/2/p38 MAPK. Conclusion: These findings suggest the possibility that ASA could be an excellent adjuvant in the treatment of chronic HCV infection. (HEPATOLOGY 2008.)

PEHPS medium: An alternative for axenic cultivation of Entamoeba histolytica and E. invadens

Knowledge of Entamoeba histolytica biology in the last 17 years has been acquired largely as a consequence of this parasites axenic cultivation in TPS-1 or TYI-S-33 media. Unfortunately, there are often low yields in these media, due to variability of their main components, Panmede and yeast extract. We describe a medium, PEHPS, of which the main components are extracts of ox liver, and ox and swine pancreas (EHP). 5 strains of E. histolytica and 2 of E. invadens were quickly and easily adapted to PEHPS and serially cultivated for 3 years. Yields progressively rose initially, and then became stable. Depending on the strain, average yields in the last 6 months of this study were 1.3 to 3.1 x 10(5) amoebae/ml for E. histolytica and 5.5 to 5.7 x 10(5) for E. invadens. All the 18 EHP batches tested supported vigorous amoebal growth. PEHPS had 2 additional advantages: (a) it was stable at 4 degrees C or 25 degrees C for 9 months, and at -10 degrees C for at least 2 years, and (b) it supported amoebal growth with inocula as low as one trophozoite/ml. PEHPS avoids the variability shown by TPS-1 and TYI-S-33, and could therefore be a good alternative for axenic amoebal cultivation.

Ancestry informative markers and admixture proportions in northeastern Mexico

To investigate the ancestral admixture in the Mestizo population in northeastern Mexico, we genotyped 74 ancestral informative markers (AIMs) and 15 Y-single-nucleotide polymorphisms (Y-SNPs) in 100 individuals. The Native American contribution is 56% (range: 27.4–81.2%), the European contribution is 38% (range: 16.7–70.5%) and the West African contribution is 6%. The results show a higher European contribution than was reported in other similar studies in the country, albeit with a predominant Native American ancestry. No remarkable differences in the ancestry proportions were observed using subgroups of 74, 54, 34 and 24 AIMs. The paternal lineage calculated by genotyping of 15 Y-SNPs, shows a major component of European and Eurasian ancestry markers (∼78%), compared with Amerindian (∼12%) and African markers (10%). This information will set a reference for future determinations of admixture proportions in the Mestizo population from Mexico and for population-based association studies of complex diseases.

Understanding the colon cancer stem cells and perspectives on treatment.

An area of research that has been recently gaining attention is the relationship between cancer stem cell (CSC) biology and chemo-resistance in colon cancer patients. It is well recognized that tumor initiation, growth, invasion and metastasis are promoted by CSCs. An important reason for the widespread interest in the CSC model is that it can comprehensibly explain essential and poorly understood clinical events, such as therapy resistance, minimal residual disease, and tumor recurrence. This review discusses the recent advances in colon cancer stem cell research, the genes responsible for CSC chemoresistance, and new therapies against CSCs.

Analyses of chondrogenic induction of adipose mesenchymal stem cells by combined co-stimulation mediated by adenoviral gene transfer.

IntroductionAdipose-derived stem cells (ASCs) have the potential to differentiate into cartilage under stimulation with some reported growth and transcriptional factors, which may constitute an alternative for cartilage replacement approaches. In this study, we analyzed the in vitro chondrogenesis of ASCs transduced with adenoviral vectors encoding insulin-like growth factor-1 (IGF-1), transforming growth factor beta-1 (TGF-β1), fibroblast growth factor-2 (FGF-2), and sex-determining region Y-box 9 (SOX9) either alone or in combinations.MethodsAggregate cultures of characterized ovine ASCs were transduced with 100 multiplicity of infections of Ad.IGF-1, Ad.TGF-β1, Ad.FGF-2, and Ad.SOX9 alone or in combination. These were harvested at various time points for detection of cartilage-specific genes expression by quantitative real-time PCR or after 14 and 28 days for histologic and biochemical analyses detecting proteoglycans, collagens (II, I and X), and total sulfated glycosaminoglycan and collagen content, respectively.ResultsExpression analyses showed that co-expression of IGF-1 and FGF-2 resulted in higher significant expression levels of aggrecan, biglycan, cartilage matrix, proteoglycan, and collagen II (all P ≤0.001 at 28 days). Aggregates co-transduced with Ad.IGF-1/Ad.FGF-2 showed a selective expression of proteoglycans and collagen II, with limited expression of collagens I and × demonstrated by histological analyses, and had significantly greater glycosaminoglycan and collagen production than the positive control (P ≤0.001). Western blot analyses for this combination also demonstrated increased expression of collagen II, while expression of collagens I and × was undetectable and limited, respectively.ConclusionCombined overexpression of IGF-1/FGF-2 within ASCs enhances their chondrogenic differentiation inducing the expression of chondrogenic markers, suggesting that this combination is more beneficial than the other factors tested for the development of cell-based therapies for cartilage repair.

Human bone morphogenetic protein 2-transduced mesenchymal stem cells improve bone regeneration in a model of mandible distraction surgery.

BackgroundBone morphogenetic proteins (BMPs) are actively involved in ossification, and BMP-2 participates throughout the entire process. Gene therapy for bone regeneration using adenovirus-expressing BMPs has been successful in small mammals, but it has not been satisfactory in large mammals. MethodsWe generated a 3-component implant (3C graft) comprising autologous mesenchymal stem cells (MSCs), ex vivo transduced with an adenovirus vector–expressing BMP-2 and embedded in a demineralized human bone matrix (DBM). ResultsIn vitro studies demonstrated vector-induced osteogenesis; osteoblast population and mineralization of the extracellular matrix were greater in the vector-transduced cultures than in the controls (nontransduced MSCs stimulated with osteogenic media were used as positive controls, and nontransduced MSCs served as a negative control). The 3-component grafts were used to fill osteotomies created by bone distraction surgery in mongrel dogs. Control groups comprised dogs with bone distraction alone and dogs with nontransduced MSC grafts. The radiography follow-up, performed 10 weeks after distraction, demonstrated a remarkable reduction in the consolidation period compared with controls. Postmortem mandibles submitted for anatomic and histologic analyses showed improved remodeling and bone maturation in the 3C-grafted dogs. Inflammatory infiltrates were not observed in any of the treated areas, and no liver toxicity was detected. ConclusionsWe demonstrated acceleration of osteogenesis in a dog model for bone distraction by using an implant of BMP-2 modified MSCs. These results are helpful for future clinical trials of mandible bone distraction.

Additive effect of ethanol and HCV subgenomic replicon expression on COX‐2 protein levels and activity

Summary.  The mechanisms by which alcohol exacerbates liver injury in patients with hepatitis C are unknown. We used the hepatitis C virus (HCV) subgenomic replicon cell system to evaluate the effect of ethanol on HCV replication and viral protein synthesis. Our results demonstrate that alcohol stimulates HCV replicon expression at both HCV‐RNA and protein levels. Furthermore, we observed that ethanol treatment showed an additive effect in cyclooxygenase‐2 (COX‐2) protein expression and activity already induced by HCV viral proteins, and in turn increased HCV viral expression. Our results suggest that COX‐2 activity is involved in ethanol‐induced HCV‐RNA and NS5A protein expression, because acetylsalicylic acid (ASA), a COX‐1/2 inhibitor, blocked this induction and downregulated COX‐2 protein expression and activity. Therefore, we suggest that ethanol increases HCV replication expression, at least in part, by upregulating a key cellular regulator of oxidative stress pathway known as COX‐2 or its products.

Isolation of an Entamoeba histolytica intracellular alkaline phospholipase A2.

Abstract The major hemolytic activity of Entamoeba histolytica is located in a subcellular fraction called P30. Its maximal effect is observed at pH 8.0 and 1 mM Ca2+ and is due to a phospholipase A (PLA). In the present study a membrane-associated phospholipase A2 was purified from P30 to homogeneity. P30 was fractionated with ethyl ether and the insoluble fraction was extracted with 1 M KCl. The KCl-soluble material was diluted ten times with 0.1 M TRIS-HCl (pH 9.5) and passed through a chromatofocusing column with a 9–4 pH gradient. Four peaks with PLA2 activity were obtained. By affinity chromatography, peak II, the one with the highest specific activity, was resolved in three more PLA2 peaks. Peak II.2 had the highest PLA2 specific activity. When analyzed by sodium dodecyl sulfate-polyacrylamide slab-gel electrophoresis under nonreducing conditions, peak II.2 yielded a single band with an apparent molecular mass of 30 kDa. Under reducing conditions the protein dissociated into two 15-kDa monomers. The purified PLA II.2 displayed its activity at the same conditions under which the P30 hemolytic activity was maximal. The isoelectric point of PLA II.2 was 7.0. The purification procedure described above provides sufficient material for determination of the relative importance of the enzyme in the E. histolytica pathogenic mechanisms.

Identification ofEntamoeba histolytica intracellular phospholipase A and lysophospholipase L1 activities

Entamoeba histolytica phospholipase A and lysophospholipase activities from a vesicular subcellular fraction (P30) were analyzed. The products, obtained using specific substrates labeled with14C or3H, indicated the presence of phospholipase A1 and A2 as well as lysophospholipase L1 activities. The enzymes detected could participate in phospholipid metabolism and the alkaline phospholipase A2 may contribute toE. histolytica cytopathogenicity.

Saturated lipids decrease mitofusin 2 leading to endoplasmic reticulum stress activation and insulin resistance in hypothalamic cells

Endoplasmic reticulum (ER) and mitochondria dysfunction contribute to insulin resistance generation during obesity and diabetes. ER and mitochondria interact through Mitofusin 2 (MTF2), which anchors in the outer mitochondrial and ER membranes regulating energy metabolism. Ablation of MTF2 leads to ER stress activation and insulin resistance. Here we determine whether lipotoxic insult induced by saturated lipids decreases MTF2 expression leading to ER stress response in hypothalamus and its effects on insulin sensitivity using in vitro and in vivo models. We found that lipotoxic stimulation induced by palmitic acid, but not the monounsaturated palmitoleic acid, decreases MTF2 protein levels in hypothalamic mHypoA-CLU192 cells. Also, palmitic acid incubation activates ER stress response evidenced by increase in the protein levels of GRP78/BIP marker at later stage than MTF2 downregulation. Additionally, we found that MTF2 alterations induced by palmitic, but not palmitoleic, stimulation exacerbate insulin resistance in hypothalamic cells. Insulin resistance induced by palmitic acid is prevented by pre-incubation of the anti-inflammatory and the ER stress release reagents, sodium salicylate and 4 phenylbutirate, respectively. Finally, we demonstrated that lipotoxic insult induced by high fat feeding to mice decreases MTF2 proteins levels in arcuate nucleus of hypothalamus. Our data indicate that saturated lipids modulate MTF2 expression in hypothalamus coordinating the ER stress response and the susceptibility to insulin resistance.