Biomechanical and biochemical regulation of cathepsin K expression in endothelial cells converge at AP-1 and NF-κB.

Cathepsins K and V are powerful elastases elevated in endothelial cells by tumor necrosis factor-α (TNFα) stimulation and disturbed blood flow both of which contribute to inflammation-mediated arterial remodeling. However, mechanisms behind endothelial cell integration of biochemical and biomechanical cues to regulate cathepsin production are not known. To distinguish these mechanisms, human aortic endothelial cells (HAECs) were stimulated with TNFα and exposed to pro-remodeling or vasoprotective shear stress profiles. TNFα upregulated cathepsin K via JNK/c-jun activation, but vasoprotective shear stress inhibited TNFα-stimulated cathepsin K expression. JNK/c-jun were still phosphorylated, but cathepsin K mRNA levels were significantly reduced to almost null indicating separate biomechanical regulation of cathepsin K by shear stress separate from biochemical stimulation. Treatment with Bay 11-7082, an inhibitor of IκBα phosphorylation, was sufficient to block induction of cathepsin K by both pro-remodeling shear stress and TNFα, implicating NF-κB as the biomechanical regulator, and its protein levels were reduced in HAECs by vasoprotective shear stress. In conclusion, NF-κB and AP-1 activation were necessary to activate cathepsin K expression in endothelial cells, highlighting integration of biochemical and biomechanical stimuli to control cathepsins K and V, powerful elastases implicated for arterial remodeling due to chronic inflammation and disturbed blood flow.

B-lymphoid cells with attributes of dendritic cells regulate T cells via indoleamine 2,3-dioxygenase.

A discrete population of splenocytes with attributes of dendritic cells (DCs) and coexpressing the B-cell marker CD19 is uniquely competent to express the T-cell regulatory enzyme indoleamine 2,3-dioxygenase (IDO) in mice treated with TLR9 ligands (CpGs). Here we show that IDO-competent cells express the B-lineage commitment factor Pax5 and surface immunoglobulins. CD19 ablation abrogated IDO-dependent T-cell suppression by DCs, even though cells with phenotypic attributes matching IDO-competent cells developed normally and expressed IDO in response to interferon gamma. Consequently, DCs and regulatory T cells (Tregs) did not acquire T-cell regulatory functions after TLR9 ligation, providing an alternative perspective on the known T-cell regulatory defects of CD19-deficient mice. DCs from B-cell-deficient mice expressed IDO and mediated T-cell suppression after TLR9 ligation, indicating that B-cell attributes were not essential for B-lymphoid IDO-competent cells to regulate T cells. Thus, IDO-competent cells constitute a distinctive B-lymphoid cell type with quintessential T-cell regulatory attributes and phenotypic features of both B cells and DCs.

Threshold control strategy for a Filippov model with group defense of pests and a constant-rate release of natural enemies.

In this paper, we establish an integrated pest management Filippov model with group defense of pests and a constant rate release of natural enemies. First, the dynamics of the subsystems in the Filippov system are analyzed. Second, the dynamics of the sliding mode system and the types of equilibria of the Filippov system are discussed. Then the complex dynamics of the Filippov system are investigated by using numerical analysis when there is a globally asymptotically stable limit cycle and a globally asymptotically stable equilibrium in two subsystems, respectively. Furthermore, we analyze the existence region of a sliding mode and pseudo equilibrium, as well as the complex dynamics of the Filippov system, such as boundary equilibrium bifurcation, the grazing bifurcation, the buckling bifurcation and the crossing bifurcation. These complex sliding bifurcations reveal that the selection of key parameters can control the population density no more than the economic threshold, so as to prevent the outbreak of pests.

Effects of masks on the transmission of infectious diseases.

In the present paper, based on the conditions that asymptomatic virus carriers are contagious and all symptomatic infected individuals wear masks, we study the impact of wearing masks in the susceptible and the asymptomatic virus carriers on the spread of infectious diseases by developing a differential equation model. At first, we give the existence, uniqueness, boundedness, and positivity of the solution as well as the basic reproduction number R 0 for the established model. Then, for two cases of wearing masks in the susceptible and the asymptomatic virus carriers where the proportion of wearing masks is fixed and the proportion of wearing masks changes with time, the results of the numerical simulation are shown in a series of pictures, and quantitative description of effects of the proportion of the population wearing masks, the protective effect of masks, and the time when they start wearing masks on the epidemic is given. Our results show that under the situation that the proportion of wearing masks is positively related to the confirmed new cases and new deaths, though the proportion will be close to 1 during the high incidence of patients, the effect on controlling the spread of such infectious diseases is far worse than the case of always maintaining a relatively higher proportion (≥0.66) of wearing masks.

A computational strategy for metabolic network construction based on the overlapping ratio: Study of patients' metabolic responses to different dialysis patterns.

BACKGROUND: Uremia is a worldwide epidemic disease and poses a serious threat to human health. Both maintenance hemodialysis (HD) and maintenance high flux hemodialysis (HFD) are common treatments for uremia and are generally used in clinical applications. In-depth exploration of patients' metabolic responses to different dialysis patterns can facilitate the understanding of pathological alterations associated with uremia and the effects of different dialysis methods on uremia, which may be used for future personalized therapy. However, due to variations of multiple factors (i.e., genetic, epigenetic and environment) in the process of disease treatments, identification of the similarities and differences in plasma metabolite changes in uremic patients in response to HD and HFD remains challenging. METHODS: In this study, a computational strategy for metabolic network construction based on the overlapping ratio (MNC-OR) was proposed for disease treatment effect research. In MNC-OR, the overlapping ratio was introduced to measure metabolic reactions and to construct metabolic networks for analysis of different treatment options. Then, MNC-OR was employed to analyze HD-pattern-dependent changes in plasma metabolites to explore the pathological alterations associated with uremia and the effectiveness of different dialysis patterns (i.e., HD and HFD) on uremia. Based on the networks constructed by MNC-OR, two network analysis techniques, namely, similarity analysis and difference analysis of network topology, were used to find the similarity and differences in metabolic signals in patients under treatment with either HD or HFD, which can facilitate the understanding of pathological alterations associated with uremia and provide the guidance for personalized dialysis therapy. RESULTS: Similarity analysis of network topology suggested that abnormal energy metabolism, gut metabolism and pyrimidine metabolism might occur in uremic patients, and maintenance of both HFD and HD therapies have beneficial effects on uremia. Then, difference analysis of network topology was employed to extract the crucial information related to HD-pattern-dependent changes in plasma metabolites. Experimental results indicated that the amino acid metabolism was closer to the normal status in HFD-treated patients; however, in HD-treated patients, the ability of antioxidation showed greater reduction, and the protein O-GlcNAcylation level was higher. Our findings demonstrate the potential of MNC-OR for explaining the metabolic similarities and differences of patients in response to different dialysis methods, thereby contributing to the guidance of personalized dialysis therapy.

Analysis of a hybrid pest management model incorporating pest resistance and different control strategies.

In this paper, we describe a hybrid dynamical model incorporating residual and delayed effects of pesticides and pest resistance to simulate the process of integrated pest management. It assumes that spraying pesticides is more frequently used than releasing natural enemies. The threshold condition for pest-eradication is given. Combined with numerical simulations, the effects of chemical control factors on the threshold are discussed. The results confirm that it is not that the more frequently the pesticides are sprayed and the stronger effects the pesticides have on pests, the smaller the threshold is. Further, we give three different control strategies, including switching pesticide strategy and strategy for releasing natural enemies elastically for the pest-eradication, and the state feedback strategy for controlling pests not exceeding the economic injury level (EIL). The results indicate that if the purpose is to prevent the density of pest population from increasing to the EIL, from an ecological and economic perspective, it is not that the more natural enemies are released, and the better results are obtained.

Effects of glucose-dependent insulinotropic peptide on behavior.

Glucose-dependent insulinotropic peptide (GIP) is an incretin hormone that rises rapidly in response to nutrient ingestion. The GIP receptor is widely expressed in the brain including the brain stem, telencephalon, diencephalon, olfactory bulb, pituitary, and cerebellum. Until recently it was not clear what the endogenous ligand for this receptor was because no GIP expression had been demonstrated in the brain. GIP synthesis has now been documented in the dentate gyrus of the hippocampus. To define GIP effects on behavior we utilized a mouse model a GIP-overexpressing transgenic mouse (GIP Tg). Specifically, anxiety-related behavior, exploration, memory, and nociception were examined. Compared to age-matched adult male C57BI/6 controls GIP Tg mice displayed enhanced exploratory behavior in the open-field locomotor activity test. GIP Tg mice also demonstrated increased performance in some of the motor function tests. These data suggest that the GIP receptor plays a role in the regulation of locomotor activity and exploration. To our knowledge, this is the first report of effects of GIP on behavior.

Elevated interleukin-6 expression levels are associated with intervertebral disc degeneration.

The present study aimed to investigate whether serum interleukin-6 (IL-6) expression levels were associated with the onset and progression of intervertebral disc degeneration (IDD). A comprehensive meta-analysis of the scientific literature from numerous electronic databases was performed, in order to obtain published studies associated with the topic of interest. Relevant case-control studies that had previously assessed a correlation between IL-6 expression levels and IDD were identified using predetermined inclusion and exclusion criteria. The STATA version 12.0 software was used for statistical analysis of the extracted data. A total of 112 studies were initially retrieved, with eight studies meeting the inclusion criteria. These contained a total of 392 subjects, of which 263 were patients with IDD and 129 were healthy controls. A meta-analysis of the eight studies demonstrated that serum IL-6 protein expression levels may be associated with IDD, and this was irrespective of IDD subtype (bulging, protrusion, or sequestration). Notably, serum expression levels of the IL-6 protein were upregulated in intervertebral disc (IVD) protrusion tissue, as compared with normal IVD tissue; thus suggesting that IL-6 may have an important role in the pathophysiological process of IDD.

Multiple melanocortin receptors are expressed in bone cells.

Melanocortin receptors belong to the seven transmembrane domain, G-protein coupled family of receptors. There are five members of this receptor family labeled MC1R-MC5R. These receptors are activated by fragments derived from a larger molecule, proopiomelanocortin (POMC) and include ACTH, alpha beta and gamma-MSH and beta-endorphin. Because of in vitro and in vivo data suggesting direct effects of these POMC molecules on bone and bone turnover, we examined bone and bone derived cells for the presence of the various members of the melanocortin receptor family. We report that the five known melanocortin receptors are expressed to varying degrees in osteoblast-like and osteoclastic cells. POMC fragments increased proliferation and expression of a variety of genes in osteoblastic cells. Furthermore, POMC mRNA was detected in osteoclastic cells. These data demonstrate that POMC-derived peptide hormones acting through high affinity melanocortin receptors have specific effects on bone cells. Thus, in addition to the indirect effects of POMC-derived hormones on bone turnover through their modulation of steroid hormone secretion, POMC fragments may have direct and specific effects on bone cell subpopulations.

Association between the interaction of SMAD3 polymorphisms with body mass index and osteoarthritis susceptibility.

PURPOSE: This study aimed to investigate the relationship between the interaction of SMAD3 polymorphisms (rs12102171 and rs2289263) with body mass index (BMI) and osteoarthritis (OA) susceptibility. METHODS: This study involved 112 OA patients and 120 healthy people. The controls were frequency-matched with the cases by age and sex. Hardy-Weinberg equilibrium (HWE) was tested by χ(2) test in the control group. The rs12102171 and rs2289263 polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The relative risk of OA was represented by odds ratio (OR) with 95% confidence interval (CI) calculated by chi-squared test. Gene-environment interaction was analyzed by crossover analysis. RESULTS: The TT genotype and T allele of SMAD3 rs12102171 polymorphism were more frequent in case than control groups (P=0.04 in both of two polymorphisms), which increased the risk of OA (OR=3.39, 95% CI=1.03-11.11 and OR=1.64, 95% CI=1.03-2.59). GG genotype and G allele were also the risk factors for OA (OR=3.22, 95% CI=1.09-9.51 and OR=1.57, 95% CI=1.02-2.42). The BMI had interactions with genotype CC and CT+TT of rs12102171 and TT and TG+GG of rs2289263 (rs12102171: OR=2.15, P=0.02 and OR=3.99, P=1.00×10(-3); rs2289263: OR=2.73, P=4.00×10(-3) and OR=4.67, P=0). CONCLUSIONS: CC and CT+TT and TT and TG+GG genotypes of SMAD3 rs12102171 and rs2289263 polymorphisms together with BMI may be susceptible factors to OA, and interactions there between can possibly confer risk to OA.

Characterization of transcription factor networks involved in umbilical cord blood CD34+ stem cells-derived erythropoiesis.

Fetal stem cells isolated from umbilical cord blood (UCB) possess a great capacity for proliferation and differentiation and serve as a valuable model system to study gene regulation. Expanded knowledge of the molecular control of hemoglobin synthesis will provide a basis for rational design of therapies for ß-hemoglobinopathies. Transcriptome data are available for erythroid progenitors derived from adult stem cells, however studies to define molecular mechanisms controlling globin gene regulation during fetal erythropoiesis are limited. Here, we utilize UCB-CD34+ stem cells induced to undergo erythroid differentiation to characterize the transcriptome and transcription factor networks (TFNs) associated with the γ/ß-globin switch during fetal erythropoiesis. UCB-CD34+ stem cells grown in the one-phase liquid culture system displayed a higher proliferative capacity than adult CD34+ stem cells. The γ/ß-globin switch was observed after day 42 during fetal erythropoiesis in contrast to adult progenitors where the switch occurred around day 21. To gain insights into transcription factors involved in globin gene regulation, microarray analysis was performed on RNA isolated from UCB-CD34+ cell-derived erythroid progenitors harvested on day 21, 42, 49 and 56 using the HumanHT-12 Expression BeadChip. After data normalization, Gene Set Enrichment Analysis identified transcription factors (TFs) with significant changes in expression during the γ/ß-globin switch. Forty-five TFs were silenced by day 56 (Profile-1) and 30 TFs were activated by day 56 (Profile-2). Both GSEA datasets were analyzed using the MIMI Cytoscape platform, which discovered TFNs centered on KLF4 and GATA2 (Profile-1) and KLF1 and GATA1 for Profile-2 genes. Subsequent shRNA studies in KU812 leukemia cells and human erythroid progenitors generated from UCB-CD34+ cells supported a negative role of MAFB in γ-globin regulation. The characteristics of erythroblasts derived from UCB-CD34+ stem cells including prolonged γ-globin expression combined with unique TFNs support novel mechanisms controlling the γ/ß-globin switch during UCB-derived erythropoiesis.

Impact of glucose-dependent insulinotropic peptide on age-induced bone loss.

UNLABELLED: GIP is an important hormonal link between nutrition and bone formation. We show for the first time that BMSCs express functional GIP receptors, that expression decreases with aging, and that elevations in GIP can prevent age-associated bone loss. INTRODUCTION: We previously showed that C57BL/6 mice lose bone mass as they age, particularly between 18 and 24 mo of age. The mechanisms involved in this age-dependent induced bone loss are probably multifactorial, but adequate nutrition and nutritional signals seem to be important. Glucose-dependent insulinotropic peptide (GIP) is an enteric hormone whose receptors are present in osteoblasts, and GIP is known to stimulate osteoblastic activity in vitro. In vivo, GIP-overexpressing C57BL/6 transgenic (GIP Tg(+)) mice have increased bone mass compared with controls. Bone histomorphometric data suggest that GIP increases osteoblast number, possibly by preventing osteoblastic apoptosis. However, potential GIP effects on osteoblastic precursors, bone marrow stromal cells (BMSCs), had not previously been examined. In addition, effects of GIP on age-induced bone loss were not known. MATERIALS AND METHODS: Changes in BMD, biomechanics, biomarkers of bone turnover, and bone histology were assessed in C57BL/6 GIP Tg(+) versus Tg(-) (littermate) mice between the ages of 1 and 24 mo of age. In addition, age-related changes in GIP receptor (GIPR) expression and GIP effects on differentiation of BMSCs were also assessed as potential causal factors in aging-induced bone loss. RESULTS: We report that bone mass and bone strength in GIP Tg(+) mice did not drop in a similar age-dependent fashion as in controls. In addition, biomarker measurements showed that GIP Tg(+) mice had increased osteoblastic activity compared with wildtype control mice. Finally, we report for the first time that BMSCs express GIPR, that the expression decreases in an age-dependent manner, and that stimulation of BMSCs with GIP led to increased osteoblastic differentiation. CONCLUSIONS: Our data show that elevated GIP levels prevent age-related loss of bone mass and bone strength and suggest that age-related decreases in GIP receptor expression in BMSCs may play a pathophysiological role in this bone loss. We conclude that elevations in GIP may be an effective countermeasure to age-induced bone loss.

Effects of glucose-dependent insulinotropic peptide on osteoclast function.

Acute nutrient ingestion leads to a rapid inhibition of bone resorption while effects on makers of bone formation are less marked or absent, suggesting that there is a transient shift toward skeletal accretion in the immediate postprandial period. The cellular bases for these effects are not clear. Glucose-dependent insulinotropic peptide (GIP), a known modulator of glucose-induced insulin secretion, is secreted from intestinal endocrine cells in response to nutrient ingestion. In addition to the effect of GIP on pancreatic beta-cells, GIP receptors are expressed by osteoclastic cells [corrected] in bone, suggesting a role for this incretin hormone in bone formation. To determine whether GIP also plays a role in the anti-resorptive effect of nutrient ingestion, osteoclasts were analyzed for the presence of GIP receptors by PCR, immunohistochemical and immunocytochemical analyses of bone tissue, and freshly isolated mature osteoclasts and osteoclast-like cells cultured in vitro. Osteoclast function was assessed by fetal long bone resorption assay and by use of the Osteologic disc assay. Our results demonstrate that GIP receptor transcripts and protein are present in osteoclasts. In addition, with the use of an in vitro organ culture system and mature osteoclasts, GIP was found to inhibit bone resorption in the organ culture system and the resorptive activity of mature osteoclasts. These data are consistent with the hypothesis that GIP inhibits bone breakdown through a direct effect on osteoclast-resorptive activity and suggest one mechanism for the postprandial reduction in markers of bone breakdown.

Disordered osteoclast formation in RAGE-deficient mouse establishes an essential role for RAGE in diabetes related bone loss.

The mechanisms underlying diabetes-mediated bone loss are not well defined. It has been reported that the advanced glycation endproducts (AGEs) and receptor for AGEs (RAGEs) are involved in diabetic complications. Here, mice deficient in RAGE were used as a model for investigating the effects of RAGE on bone mass. We found that RAGE-/- mice have a significantly increased bone mass and bone biomechanical strength and a decreased number of osteoclasts compared to wild-type mice. The serum levels of IL-6 and bone breakdown marker pyridinoline were significantly decreased in RAGE-/- mice. RAGE-/- mice maintain bone mass following ovariectomy, whereas wild-type mice lose bone mass. Furthermore, osteoclast-like cells do express RAGE mRNA. Our data therefore indicate that RAGE serves as a positive factor to regulate the osteoclast formation, directly implicates a role for RAGE in diabetes-promoted bone destruction, and documents that the AGE-RAGE interaction may account for diabetes associated bone loss.

An increase in surface area is not required for cell division in early sea urchin development.

Cell division requires an increase in surface area to volume ratio. During early development, surface area can increase, volume can decrease, or surface topography can be optimized to allow for division. While exocytosis is thought to be essential for division [Mol. Biol. Cell 10 (1999), 2735; Proc. Natl. Acad. Sci. USA 99 (2002), 3633], exocytosis doesn't always yield an increase in surface area [Proc. Natl. Acad. Sci. USA 79 (1982), 6712]. We used multiphoton laser scanning microscopy, fluorescence spectroscopy, and electron microscopy to monitor membrane trafficking, surface area, volume, and surface topography during early sea urchin development. Despite extensive membrane trafficking monitored by FM 1-43 fluorescence, we find that the net surface area of the embryo does not change prior to the eight-cell stage. During this period, embryo volume decreases by 15%, and microvilli disappear from interior facing membrane segments. Thus, the first three cell divisions utilize residual membrane liberated by decreasing cytoplasmic volume, and reducing microvilli density on interior facing membranes. Only after the eight-cell stage was a net increase in FM 1-43 fluorescence from the embryo surface detected. Our data suggest that compensatory endocytosis is downregulated after this developmental stage to yield an increase in surface area for cell division.