Small Heat-Shock Proteins,IbpAB, Protect Non-Pathogenic Escherichia coli from Killing by Macrophage-Derived Reactive Oxygen Species

Many intracellular bacterial pathogens possess virulence factors that prevent detection and killing by macrophages. However, similar virulence factors in non-pathogenic bacteria are less well-characterized and may contribute to the pathogenesis of chronic inflammatory conditions such as Crohn’s disease. We hypothesize that the small heat shock proteins IbpAB, which have previously been shown to reduce oxidative damage to proteins in vitro and be upregulated in luminal non-pathogenic Escherichia strain NC101 during experimental colitis in vivo, protect commensal E. coli from killing by macrophage-derived reactive oxygen species (ROS). Using real-time PCR, we measured ibpAB expression in commensal E. coli NC101 within wild-type (wt) and ROS-deficient (gp91phox^-/-) macrophages and in NC101 treated with the ROS generator paraquat. We also quantified survival of NC101 and isogenic mutants in wt and gp91phox^-/- macrophages using gentamicin protection assays. Similar assays were performed using a pathogenic E. coli strain O157:H7. We show that non-pathogenic E. coli NC101inside macrophages upregulate ibpAB within 2 hrs of phagocytosis in a ROS-dependent manner and that ibpAB protect E. coli from killing by macrophage-derived ROS. Moreover, we demonstrate that ROS-induced ibpAB expression is mediated by the small E. coli regulatory RNA, oxyS. IbpAB are not upregulated in pathogenic E. coli O157:H7 and do not affect its survival within macrophages. Together, these findings indicate that ibpAB may be novel virulence factors for certain non-pathogenic E. coli strains.     

A Method for Identification and Analysis of Non-Overlapping Myeloid Immunophenotypes in Humans

The development of flow cytometric biomarkers in human studies and clinical trials has been slowed by inconsistent sample processing, use of cell surface markers, and reporting of immunophenotypes. Additionally, the function(s) of distinct cell types as biomarkers cannot be accurately defined without the proper identification of homogeneous populations. As such, we developed a method for the identification and analysis of human leukocyte populations by the use of eight 10-color flow cytometric protocols in combination with novel software analyses. This method utilizes un-manipulated biological sample preparation that allows for the direct quantitation of leukocytes and non-overlapping immunophenotypes. We specifically designed myeloid protocols that enable us to define distinct phenotypes that include mature monocytes, granulocytes, circulating dendritic cells, immature myeloid cells, and myeloid derived suppressor cells (MDSCs). We also identified CD123 as an additional distinguishing marker for the phenotypic characterization of immature LIN^-CD33⁺HLA-DR^- MDSCs. Our approach permits the comprehensive analysis of all peripheral blood leukocytes and yields data that is highly amenable for standardization across inter-laboratory comparisons for human studies.     

Distribution and function of prophage phiRv1 and phiRv2 among Mycobacterium tuberculosis complex

Mycobacterium tuberculosis complex (MTBC) is notorious for causing diseases, such as tuberculosis. Tuberculosis caused by M. tuberculosis remains a global public health concern. Two prophages, phiRv1 and phiRv2, can be found among most MTBC genomes. However, no precise functions have been assigned for the two prophages. In this paper, to find out the function of these two prophages, the distribution and function of phiRv1 and phiRv2 in MTBC genomes were analyzed from multiple omics data. We found that complex insertion, deletion, and reorganization appeared on the locus of two prophages in MTBC genomes; some genes of the two prophages can be translated and are functional from proteomic data; the expression of other prophage genes, such as Rv1577c, Rv2650c, Rv2652c, Rv2659c, and Rv2658c, can vary with environmental stresses and might enhance the fitness of MTBC. These data will facilitate our in-depth understanding of their function.     

Hepatitis B Virus Pre-S2 Mutant Induces Aerobic Glycolysis through Mammalian Target of Rapamycin Signal Cascade

Hepatitis B virus (HBV) pre-S2 mutant can induce hepatocellular carcinoma (HCC) via the induction of endoplasmic reticulum stress to activate mammalian target of rapamycin (MTOR) signaling. The association of metabolic syndrome with HBV-related HCC raises the possibility that pre-S2 mutant-induced MTOR activation may drive the development of metabolic disorders to promote tumorigenesis in chronic HBV infection. To address this issue, glucose metabolism and gene expression profiles were analyzed in transgenic mice livers harboring pre-S2 mutant and in an in vitro culture system. The pre-S2 mutant transgenic HCCs showed glycogen depletion. The pre-S2 mutant initiated an MTOR-dependent glycolytic pathway, involving the eukaryotic translation initiation factor 4E binding protein 1 (EIF4EBP1), Yin Yang 1 (YY1), and myelocytomatosis oncogene (MYC) to activate the solute carrier family 2 (facilitated glucose transporter), member 1 (SLC2A1), contributing to aberrant glucose uptake and lactate production at the advanced stage of pre-S2 mutant transgenic tumorigenesis. Such a glycolysis-associated MTOR signal cascade was validated in human HBV-related HCC tissues and shown to mediate the inhibitory effect of a model of combined resveratrol and silymarin product on tumor growth. Our results provide the mechanism of pre-S2 mutant-induced MTOR activation in the metabolic switch in HBV tumorigenesis. Chemoprevention can be designed along this line to prevent HCC development in high-risk HBV carriers.     

Analysis and assessment of heavy metals pollution in soils around a Pb and Zn smelter in Baoji City,Northwest China

Soil heavy metal pollution from mining activities is potentially harmful to human health through the food chain. In this study, a total of 43 soil samples were collected from a depth of 0–20 cm from fields close to a Pb and Zn smelter. The samples were used to: 1) analyze the pollution level of heavy metals (Pb, Zn, Cr, and Cu) and spatial distribution pattern; 2) evaluate the degree of accumulation and enrichment, potential ecological risk, and human health risk; and 3) perform source apportionment in Fengxiang County, Shaanxi Province of China. The results showed that the concentration ranged from 43.67 to 189.55, 131.43 to 239.53, 74.77 to 112.25, and 24.69 to 37.71 mg·kg^?1 for Pb, Zn, Cr, and Cu, respectively, and the mean concentration for Pb, Zn, Cr, and Cu was 129.46, 192.85, 91.98 and 31.67 mg·kg^?1, respectively. The concentrations were greater than the Shaanxi Province background values, while they were lower than the second-level limits of Environmental Quality Standard for Soils of China (EQSS). The spatial distribution of heavy metal contents showed a banded in soil except Cu. The spatial distribution pattern and pollution assessment indexes (I_geo, EF) indicated that the investigated metals had been accumulated in the study areas, and implied significant influences from anthropogenic activities, local meteorological situation, and soil properties. The ecological risk assessment showed that the risks were relatively low (RI<150). Compared with the exposure risk for adults, that for children was significantly greater. The ingestion of heavy metals in the soils by humans was the main exposure pathway compared with the dermal exposure. There may be a risk of noncarcinogenic adverse health effects (HQ < 1, 0.377 ≤ HI≤1.553) on children, but the adults were unlikely to experience obvious adverse health effects (HQ < 1, HI < 1). The carcinogenic risk of Cr for adults and children was at an unacceptable level. The carcinogenic and noncarcinogenic risks were in the order of children > adults. The correlation analysis showed that Pb, Cr, and Cu have identical anthropogenic and natural sources, while Zn has another identical source. This study could provide a basis for the sustainable management of this region by reducing metal inputs and to protect soils from long-term heavy metal accumulation.