Autophagy signaling and the cogwheels of cancer

The downregulation of macroautophagy observed in cancer cells is associated with tumor progression. The regulation of macroautophagy by signaling pathways overlaps with the control of cell growth, proliferation, cell survival and death. Several tumor suppressor genes (PTEN, TSC2 and p53) involved in the mTOR signaling network have been shown to stimulate autophagy. In contrast, the oncoproteins involved in this network have the opposite effect. These findings, together with the discovery that haploinsufficiency of the tumor suppressor beclin 1 promotes tumorigenesis in various tissues in transgenic mice, give credibility to the idea that autophagy is a tumor suppressor mechanism. The induction of macroautophagy by cancer treatments may also contribute to cell eradication. However, cancer cells sometimes mobilize autophagic capacities in response to various stimuli without a fatal outcome, suggesting that they can also exploit macroautophagy for their own benefit.     

Neural differentiation of human umbilical cord matrix-derived mesenchymal cells under special culture conditions

Many neural disorders are characterized by the loss of one or several types of neural cells. Human umbilical cord-derived mesenchymal cells (hUCMs) are capable of differentiating into neuron, astroglia-like and oligodendrocyte cell types. However, a reliable means of inducing the selective differentiation of hUCMs into neural cells in vitro has not yet been established. For induction of neural differentiation, hUCMs were seeded onto sterile glass slides and six various cocktails using a base medium (DMEM/LG) supplemented with 10 % FBS, retinoic acid (RA), dimethyl sulfoxide (DMSO), epidermal growth factor (EGF) and fibroblast growth factor (FGF) were used to compare their effect on neuronal, astrocyte and oligodandrocyte differentiation. The hUCMs were positive for mesenchymal markers, while they were negative for hematopoietic markers. Differentiation to adipogenic and osteogenic lineage was detected in these cells. Our data revealed that the cocktail consisting of DMEM/LG, FBS, RA, FGF, and EGF (DF/R/Fg/E group) induced hUCM cells to express the highest percentage of nestin, ß-tubulin III, neurofilament, and CNPase. The DF/Ds/Fg/E group led to the highest percentage of GFAP expression. While the expression levels of NF, GFAP, and CNPase were the lowest in the DF group. The least percentage of nestin and ß-tubulin III expression was observed in the DF/Ds group. We may conclude that FGF and EGF are important inducers for differentiation of hUCMs into neuron, astrocyte and oligodendrocyte. RA can induce hUCMs to differentiate into neuron and oligodendrocyte while for astrocyte differentiation DMSO had a pivotal role.     

Levofloxacin reduces inflammatory cytokine levels in human bronchial epithelia cells: implications for aerosol MP-376 (levofloxacin solution for inhalation) treatment of chronic pulmonary infections

Inflammation resulting from chronic bacterial infection in the lung contributes to long-term pulmonary complications in chronic pulmonary infections such as cystic fibrosis. Aerosol administration of levofloxacin as in the form of the investigational formulation MP-376 results in higher concentrations in lung tissues that are higher than those that can be attained with oral or intravenous dosing of levofloxacin. The objective of this study was to evaluate the effect of high concentrations of levofloxacin achieved with aerosol administration of MP-376 on proinflammatory cytokine secretion by immortalized human bronchial epithelia cells in vitro. Additionally, we investigated the potential mechanisms of the immunomodulatory effect of levofloxacin. In vitro studies in human lung epithelial cell lines showed that levofloxacin led to a dose-related reduction in IL-6 and IL-8 concentrations, with 300 μg mL(-1) resulting in the reduction of levels of IL-6 by fourfold and IL-8 by twofold (P<0.05); in contrast, tobramycin increased IL-6 levels by 50%, but had no effect on IL-8. Levofloxacin treatment did not affect the cytokine mRNA level and nuclear factor-κB-dependent promoter activity. These findings suggest that high concentrations of levofloxacin obtained in pulmonary tissues following the administration of aerosol MP-376 may provide additional benefits in patients with chronic pulmonary infections that are independent of its antibacterial properties.     

Exploring the complexity of the HIV-1 fitness landscape

Although fitness landscapes are central to evolutionary theory, so far no biologically realistic examples for large-scale fitness landscapes have been described. Most currently available biological examples are restricted to very few loci or alleles and therefore do not capture the high dimensionality characteristic of real fitness landscapes. Here we analyze large-scale fitness landscapes that are based on predictive models for in vitro replicative fitness of HIV-1. We find that these landscapes are characterized by large correlation lengths, considerable neutrality, and high ruggedness and that these properties depend only weakly on whether fitness is measured in the absence or presence of different antiretrovirals. Accordingly, adaptive processes on these landscapes depend sensitively on the initial conditions. While the relative extent to which mutations affect fitness on their own (main effects) or in combination with other mutations (epistasis) is a strong determinant of these properties, the fitness landscape of HIV-1 is considerably less rugged, less neutral, and more correlated than expected from the distribution of main effects and epistatic interactions alone. Overall this study confirms theoretical conjectures about the complexity of biological fitness landscapes and the importance of the high dimensionality of the genetic space in which adaptation takes place.     

Modulation of cytokine production and enhancement of cell viability by TLR7 and TLR9 ligands during anthrax infection of macrophages

Inhalation of Bacillus anthracis, a bioterrorism agent, results in a high mortality rate despite appropriate antibiotic therapy. Macrophages appear to be a key factor in B. anthracis pathogenesis. The burst of pro-inflammatory cytokines from macrophages could be a major cause of death in anthrax. However, preactivation of Toll-like receptors (TLRs) could modify the host response. TLR ligands stimulate the release of activating cytokines but may also down-modulate the subsequent deleterious cytokine response to pathogens. We developed a cell culture model to measure macrophage responses to B. anthracis spores and bacilli. We found that germination from spores to bacilli produced a substantial stimulus for the secretion of the cytokines IL-6, TNF-alpha, IL-10, and IL-12 p40. Our studies showed that pretreatment of mouse macrophages with the TLR9 ligand ISS-1018, or the TLR7 ligands R-848 and IT-37, results in a substantial decrease in the subsequent secretion of IL-6 and TNF-alpha in response to B. anthracis infection of macrophages. Furthermore, the TLR7 and TLR9 ligands significantly decreased anthrax-induced cytotoxicity in the macrophages. These findings suggest that TLR ligands may contribute to the enhancement of innate immunity in B. anthracis infection by suppressing potentially deleterious pro-inflammatory cytokine responses and by improving macrophage viability.     

Sensorimotor and Pain Modulation Brain Abnormalities in Trigeminal Neuralgia: A Paroxysmal,Sensory-Triggered Neuropathic Pain

Objective

Idiopathic trigeminal neuralgia (TN) is characterized by paroxysms of severe facial pain but without the major sensory loss that commonly accompanies neuropathic pain. Since neurovascular compression of the trigeminal nerve root entry zone does not fully explain the pathogenesis of TN, we determined whether there were brain gray matter abnormalities in a cohort of idiopathic TN patients. We used structural MRI to test the hypothesis that TN is associated with altered gray matter (GM) in brain areas involved in the sensory and affective aspects of pain, pain modulation, and motor function. We further determined the contribution of long-term TN on GM plasticity.

Methods

Cortical thickness and subcortical GM volume were measured from high-resolution 3T T1-weighted MRI scans in 24 patients with right-sided TN and 24 healthy control participants.

Results

TN patients had increased GM volume in the sensory thalamus, amygdala, periaqueductal gray, and basal ganglia (putamen, caudate, nucleus accumbens) compared to healthy controls. The patients also had greater cortical thickness in the contralateral primary somatosensory cortex and frontal pole compared to controls. In contrast, patients had thinner cortex in the pregenual anterior cingulate cortex, the insula and the orbitofrontal cortex. No relationship was observed between GM abnormalities and TN pain duration.

Conclusions

TN is associated with GM abnormalities in areas involved in pain perception, pain modulation and motor function. These findings may reflect increased nociceptive input to the brain, an impaired descending modulation system that does not adequately inhibit pain, and increased motor output to control facial movements to limit pain attacks.     

Phage biocontrol to combat Pseudomonas syringae pathogens causing disease in cherry

Bacterial canker is a major disease of Prunus species, such as cherry (Prunus avium). It is caused by Pseudomonas syringae pathovars, including P. syringae pv. syringae (Pss) and P. syringae pv. morsprunorum race 1 (Psm1) and race 2 (Psm2). Concerns over the environmental impact of, and the development of bacterial resistance to, traditional copper controls calls for new approaches to disease management. Bacteriophage-based biocontrol could provide a sustainable and natural alternative approach to combat bacterial pathogens. Therefore, seventy phages were isolated from soil, leaf and bark of cherry trees in six locations in the south east of England. Subsequently, their host range was assessed against strains of Pss, Psm1 and Psm2. While these phages lysed different Pss, Psm and some other P. syringae pathovar isolates, they did not infect beneficial bacteria such as Pseudomonas fluorescens. A subset of thirteen phages were further characterized by genome sequencing, revealing five distinct clades in which the phages could be clustered. No known toxins or lysogeny-associated genes could be identified. Using bioassays, selected phages could effectively reduce disease progression in vivo, both individually and in cocktails, reinforcing their potential as biocontrol agents in agriculture.     

Epithelial CaSR deficiency alters intestinal integrity and promotes proinflammatory immune responses

The intestinal epithelium is equipped with sensing receptor mechanisms that interact with luminal microorganisms and nutrients to regulate barrier function and gut immune responses, thereby maintaining intestinal homeostasis. Herein, we clarify the role of the extracellular calcium-sensing receptor (CaSR) using intestinal epithelium-specific Casr^−/− mice. Epithelial CaSR deficiency diminished intestinal barrier function, altered microbiota composition, and skewed immune responses towards proinflammatory. Consequently, Casr^−/− mice were significantly more prone to chemically induced intestinal inflammation resulting in colitis. Accordingly, CaSR represents a potential therapeutic target for autoinflammatory disorders, including inflammatory bowel diseases.