Effects of binge ethanol on lipid homeostasis and oxidative stress in a rat model of nonalcoholic fatty liver disease

Excess fat accumulation renders the liver more vulnerable to ethanol, but it is still unclear how alcohol enhances lipid dysmetabolism and oxidative stress in a pre-existing steatosis condition. The effects produced by binge ethanol consumption in the liver of male Wistar rats fed a standard (Ctrl) or a high-fat diet HFD were compared. The liver status was checked through tissue histology and standard serum parameters. Alteration of hepatic lipid homeostasis and consequent oxidative unbalance were assessed by quantifying the mRNA expression of the lipid-regulated peroxisome proliferator-activated receptors (PPARs), of the cytochromes CYP2E1 and CYP4A1, and of some antioxidant molecules such as the metallothionein isoforms MT1 and MT2 and the enzymes catalase and superoxide dismutase. The number of adipose differentiation-related protein (ADRP)-positive lipid droplets (LDs) was evaluated by immunohistochemical staining. As a response to the double insult of diet and ethanol the rat liver showed: (1) a larger increase in fat accumulation within ADRP-positive LDs; (2) stimulation of lipid oxidation in the attempt to limit excess fat accumulation; (3) induction of antioxidant proteins (MT2, in particular) to protect the liver from the ethanol-induced overproduction of oxygen radicals. The data indicate an increased susceptibility of fatty liver to ethanol and suggest that the synergistic effect of diet and ethanol on lipid dysmetabolism might be mediated, at least in part, by PPARs and cytochromes CYP4A1 and CYP2E1.     

Digoxin Derivatives with Enhanced Selectivity for the α2 Isoform of Na,K-ATPase: EFFECTS ON INTRAOCULAR PRESSURE IN RABBITS*

In the ciliary epithelium of the eye, the pigmented cells express the α1β1 isoform of Na,K-ATPase, whereas the non-pigmented cells express mainly the α2β3 isoform of Na,K-ATPase. In principle, a Na,K-ATPase inhibitor with selectivity for α2 could effectively reduce intraocular pressure with only minimal local and systemic toxicity. Such an inhibitor could be applied topically provided it was sufficiently permeable via the cornea. Previous experiments with recombinant human α1β1, α2β1, and α3β1 isoforms showed that the classical cardiac glycoside, digoxin, is partially α2-selective and also that the trisdigitoxose moiety is responsible for isoform selectivity. This led to a prediction that modification of the third digitoxose might increase α2 selectivity. A series of perhydro-1,4-oxazepine derivatives of digoxin have been synthesized by periodate oxidation and reductive amination using a variety of R-NH₂ substituents. Several derivatives show enhanced selectivity for α2 over α1, close to 8-fold in the best case. Effects of topically applied cardiac glycosides on intraocular pressure in rabbits have been assessed by their ability to either prevent or reverse acute intraocular pressure increases induced by 4-aminopyridine or a selective agonist of the A3 adenosine receptor. Two relatively α2-selective digoxin derivatives efficiently normalize the ocular hypertension, by comparison with digoxin, digoxigenin, or ouabain. This observation is consistent with a major role of α2 in aqueous humor production and suggests that, potentially, α2-selective digoxin derivatives could be of interest as novel drugs for control of intraocular pressure.     

Actin dynamics in growth cone motility and navigation

Motile growth cones lead growing axons through developing tissues to synaptic targets. These behaviors depend on the organization and dynamics of actin filaments that fill the growth cone leading margin [peripheral (P‐) domain]. Actin filament organization in growth cones is regulated by actin‐binding proteins that control all aspects of filament assembly, turnover, interactions with other filaments and cytoplasmic components, and participation in producing mechanical forces. Actin filament polymerization drives protrusion of sensory filopodia and lamellipodia, and actin filament connections to the plasma membrane link the filament network to adhesive contacts of filopodia and lamellipodia with other surfaces. These contacts stabilize protrusions and transduce mechanical forces generated by actomyosin activity into traction that pulls an elongating axon along the path toward its target. Adhesive ligands and extrinsic guidance cues bind growth cone receptors and trigger signaling activities involving Rho GTPases, kinases, phosphatases, cyclic nucleotides, and [Ca⁺⁺] fluxes. These signals regulate actin‐binding proteins to locally modulate actin polymerization, interactions, and force transduction to steer the growth cone leading margin toward the sources of attractive cues and away from repellent guidance cues.

     

Wilms’ Tumor Gene 1 (WT1) Silencing Inhibits Proliferation of Malignant Peripheral Nerve Sheath Tumor sNF96.2 Cell Line

Wilms’ tumor gene 1 (WT1) plays complex roles in tumorigenesis, acting as tumor suppressor gene or an oncogene depending on the cellular context. WT1 expression has been variably reported in both benign and malignant peripheral nerve sheath tumors (MPNSTs) by means of immunohistochemistry. The aim of the present study was to characterize its potential pathogenetic role in these relatively uncommon malignant tumors. Firstly, immunohistochemical analyses in MPNST sNF96.2 cell line showed strong WT1 staining in nuclear and perinuclear areas of neoplastic cells. Thus, we investigated the effects of silencing WT1 by RNA interference. Through Western Blot analysis and proliferation assay we found that WT1 knockdown leads to the reduction of cell growth in a time- and dose-dependent manner. siWT1 inhibited proliferation of sNF96.2 cell lines likely by influencing cell cycle progression through a decrease in the protein levels of cyclin D1 and inhibition of Akt phosphorylation compared to the control cells. These results indicate that WT1 knockdown attenuates the biological behavior of MPNST cells by decreasing Akt activity, demonstrating that WT1 is involved in the development and progression of MPNSTs. Thus, WT1 is suggested to serve as a potential therapeutic target for MPNSTs.     

Indoleamine 2,3-Dioxygenase Controls Fungal Loads and Immunity in Paracoccidioidomicosis but is More Important to Susceptible than Resistant Hosts

Background

Paracoccidioidomycosis, a primary fungal infection restricted to Latin America, is acquired by inhalation of fungal particles. The immunoregulatory mechanisms that control the severe and mild forms of paracoccidioidomycosis are still unclear. Indoleamine 2,3-dioxygenase (IDO), an IFN-γ induced enzyme that catalyzes tryptophan metabolism, can control host-pathogen interaction by inhibiting pathogen growth, T cell immunity and tissue inflammation.

Methodology/Principal Findings

In this study, we investigated the role of IDO in pulmonary paracoccidioidomycosis of susceptible and resistant mice. IDO was blocked by 1-methyl-dl-tryptophan (1MT), and fungal infection studied in vitro and in vivo. Paracoccidioides brasiliensis infection was more severe in 1MT treated than untreated macrophages of resistant and susceptible mice, concurrently with decreased production of kynurenines and IDO mRNA. Similar results were observed in the pulmonary infection. Independent of the host genetic pattern, IDO inhibition reduced fungal clearance but enhanced T cell immunity. The early IDO inhibition resulted in increased differentiation of dendritic and Th17 cells, accompanied by reduced responses of Th1 and Treg cells. Despite these equivalent biological effects, only in susceptible mice the temporary IDO blockade caused sustained fungal growth, increased tissue pathology and mortality rates. In contrast, resistant mice were able to recover the transitory IDO blockade by the late control of fungal burdens without enhanced tissue pathology.

Conclusions/Significance

Our studies demonstrate for the first time that in pulmonary paracoccidioidomycosis, IDO is an important immunoregulatory enzyme that promotes fungal clearance and inhibits T cell immunity and inflammation, with prominent importance to susceptible hosts. In fact, only in the susceptible background IDO inhibition resulted in uncontrolled tissue pathology and mortality rates. Our findings open new perspectives to understand the immunopathology of paracoccidioidomycosis, and suggest that an insufficient IDO activity could be associated with the severe cases of human PCM characterized by inefficient fungal clearance and excessive inflammation.     

Natural and Vaccine-Mediated Immunity to Salmonella Typhimurium is Impaired by the Helminth Nippostrongylus brasiliensis

Background

The impact of exposure to multiple pathogens concurrently or consecutively on immune function is unclear. Here, immune responses induced by combinations of the bacterium Salmonella Typhimurium (STm) and the helminth Nippostrongylus brasiliensis (Nb), which causes a murine hookworm infection and an experimental porin protein vaccine against STm, were examined.

Methodology/Principal Findings

Mice infected with both STm and Nb induced similar numbers of Th1 and Th2 lymphocytes compared with singly infected mice, as determined by flow cytometry, although lower levels of secreted Th2, but not Th1 cytokines were detected by ELISA after re-stimulation of splenocytes. Furthermore, the density of FoxP3+ T cells in the T zone of co-infected mice was lower compared to mice that only received Nb, but was greater than those that received STm. This reflected the intermediate levels of IL-10 detected from splenocytes. Co-infection compromised clearance of both pathogens, with worms still detectable in mice weeks after they were cleared in the control group. Despite altered control of bacterial and helminth colonization in co-infected mice, robust extrafollicular Th1 and Th2-reflecting immunoglobulin-switching profiles were detected, with IgG2a, IgG1 and IgE plasma cells all detected in parallel. Whilst extrafollicular antibody responses were maintained in the first weeks after co-infection, the GC response was less than that in mice infected with Nb only. Nb infection resulted in some abrogation of the longer-term development of anti-STm IgG responses. This suggested that prior Nb infection may modulate the induction of protective antibody responses to vaccination. To assess this we immunized mice with porins, which confer protection in an antibody-dependent manner, before challenging with STm. Mice that had resolved a Nb infection prior to immunization induced less anti-porin IgG and had compromised protection against infection.

Conclusion

These findings demonstrate that co-infection can radically alter the development of protective immunity during natural infection and in response to immunization.     

Ex Vivo Treatment Response of Primary Tumors and/or Associated Metastases for Preclinical and Clinical Development of Therapeutics

The molecular analysis of established cancer cell lines has been the mainstay of cancer research for the past several decades. Cell culture provides both direct and rapid analysis of therapeutic sensitivity and resistance. However, recent evidence suggests that therapeutic response is not exclusive to the inherent molecular composition of cancer cells but rather is greatly influenced by the tumor cell microenvironment, a feature that cannot be recapitulated by traditional culturing methods. Even implementation of tumor xenografts, though providing a wealth of information on drug delivery/efficacy, cannot capture the tumor cell/microenvironment crosstalk (i.e., soluble factors) that occurs within human tumors and greatly impacts tumor response. To this extent, we have developed an ex vivo (fresh tissue sectioning) technique which allows for the direct assessment of treatment response for preclinical and clinical therapeutics development. This technique maintains tissue integrity and cellular architecture within the tumor cell/microenvironment context throughout treatment response providing a more precise means to assess drug efficacy.     

A novel anti-aldolase C antibody specifically interacts with residues 85–102 of the protein

Aldolase C is a brain-specific glycolytic isozyme whose complete repertoire of functions are obscure. This lack of knowledge can be addressed using molecular tools that discriminate the protein from the homologous, ubiquitous paralog aldolase A. The anti-aldolase C antibodies currently available are polyclonal and not highly specific. We obtained the novel monoclonal antibody 9F against human aldolase C, characterized its isoform specificity and tested its performance. First, we investigated the specificity of 9F for aldolase C. Then, using bioinformatic tools coupled to molecular cloning and chemical synthesis approaches, we produced truncated human aldolase C fragments, and assessed 9F binding to these fragments by western blot and ELISA assays. This strategy revealed that residues 85–102 harbor the epitope-containing region recognized by 9F. The efficiency of 9F was demonstrated also for immunoprecipitation assays. Finally, surface plasmon resonance revealed that the protein has a high affinity toward the epitope-containing peptide. Taken together, our findings show that epitope recognition is sequence-driven and is independent of the three-dimensional structure. In conclusion, given its specific molecular interaction, 9F is a novel and powerful tool to investigate aldolase C’s functions in the brain.     

Differential activity of GSK-3 isoforms regulates NF-κB and TRAIL- or TNFα induced apoptosis in pancreatic cancer cells

While TRAIL is a promising anticancer agent due to its ability to selectively induce apoptosis in neoplastic cells, many tumors, including pancreatic ductal adenocarcinoma (PDA), display intrinsic resistance, highlighting the need for TRAIL-sensitizing agents. Here we report that TRAIL-induced apoptosis in PDA cell lines is enhanced by pharmacological inhibition of glycogen synthase kinase-3 (GSK-3) or by shRNA-mediated depletion of either GSK-3α or GSK-3β. In contrast, depletion of GSK-3β, but not GSK-3α, sensitized PDA cell lines to TNFα-induced cell death. Further experiments demonstrated that TNFα-stimulated IκBα phosphorylation and degradation as well as p65 nuclear translocation were normal in GSK-3β-deficient MEFs. Nonetheless, inhibition of GSK-3β function in MEFs or PDA cell lines impaired the expression of the NF-κB target genes Bcl-xL and cIAP2, but not IκBα. Significantly, the expression of Bcl-xL and cIAP2 could be reestablished by expression of GSK-3β targeted to the nucleus but not GSK-3β targeted to the cytoplasm, suggesting that GSK-3β regulates NF-κB function within the nucleus. Consistent with this notion, chromatin immunoprecipitation demonstrated that GSK-3 inhibition resulted in either decreased p65 binding to the promoter of BIR3, which encodes cIAP2, or increased p50 binding as well as recruitment of SIRT1 and HDAC3 to the promoter of BCL2L1, which encodes Bcl-xL. Importantly, depletion of Bcl-xL but not cIAP2, mimicked the sensitizing effect of GSK-3 inhibition on TRAIL-induced apoptosis, whereas Bcl-xL overexpression ameliorated the sensitization by GSK-3 inhibition. These results not only suggest that GSK-3β overexpression and nuclear localization contribute to TNFα and TRAIL resistance via anti-apoptotic NF-κB genes such as Bcl-xL, but also provide a rationale for further exploration of GSK-3 inhibitors combined with TRAIL for the treatment of PDA.