Transcriptional profiling of IKK2/NF-kappa B- and p38 MAP kinase-dependent gene expression in TNF-alpha-stimulated primary human endothelial cells

CRIP1 Reshapes the Gastric Cancer Microenvironment to Facilitate Development of Lymphatic Metastasis

Lymphangiogenesis in tumors provides an auxiliary route for cancer cell invasion to drainage lymph nodes, facilitating the development of lymphatic metastasis (LM). However, the mechanisms governing tumor lymphangiogenesis and lymphatic permeability in gastric cancer (GC) remain largely unknown. Here, the unprecedented role and mechanism of cysteine-rich intestinal protein-1 (CRIP1) in mediating the development of GC LM is uncovered. A series of assays are performed to identify downstream targets of CRIP1, and rescue experiments are performed to confirm the effects of this regulatory axis on LM. CRIP1 overexpression facilitates LM in GC by promoting lymphangiogenesis and lymphatic vessel permeability. CRIP1 promotes phosphorylation of cAMP responsive element binding protein 1(CREB1), which then mediates vascular endothelial growth factor C (VEGFC) expression necessary for CRIP1-induced lymphangiogenesis and transcriptionally promotes C-C motif chemokine ligand 5 (CCL5) expression. CCL5 recruits macrophages to promote tumor necrosis factor alpha (TNF-α) secretion, eventually enhancing lymphatic permeability. The study highlights CRIP1 regulates the tumor microenvironment to promote lymphangiogenesis and LM in GC. Considering the current limited understanding of LM development in GC, these pathways provide potential targets for future therapeutics.

Multi-Layered Human Blood Vessels-on-Chip Design Using Double Viscous Finger Patterning

Blood vessel-on-a-chip models aim at reproducing vascular functions. However, very few efficient methods have been designed to address the need for biological replicates in medium- to high-throughput screenings. Here, vessels-on-chip were designed in polydimethylsiloxane-glass chips using the viscous finger patterning technique which was adapted to create channels with various internal diameters inside a collagen solution and to simultaneously seed cells. This method was refined to create blood vessels composed of two concentric, distinct, and closely appositioned layers of human endothelial and perivascular cells arranged around a hollow lumen. These approaches allowed the formation of structurally correct blood vessels-on-chips which were constituted of either only endothelial cells or of both cell types in order to distinguish the vascular barrier reactivity to drugs in the presence or not of perivascular cells. The established vessels showed a tight vascular barrier, as assessed by immunostaining of the adherens junctions, and were reactive to the natural vasopermeant thrombin and to inflammatory cytokines. The presence of perivascular cells markedly increased the tightness of the vascular barrier and lowered its response to thrombin. The design allowed us to simultaneously challenge in real-time several tens of 3D-reconstituted, multicellular blood vessels in a standard multiwell plate format suitable for high-throughput drug screening.

Anti-angiogenic Properties of Bevacizumab Improve Respiratory System Inflammation in Ovalbumin-Induced Rat Model of Asthma

Studies on the bronchial vascular bed have revealed that the number of blood vessels in the lamina propria and under the mucosa of the lung tissue increases in patients suffering from mild to severe asthma. Thus, in this study, a new strategy was employed in respiratory system disorders by angiogenesis inhibition in an ovalbumin (OVA)-induced rat model of asthma. Twenty-one male Wistar albino rats, 8 weeks old, were randomly divided into three groups (n = 7 in each group), including (1) control group, (2) OVA-treated group, and (3) OVA + Bmab (bevacizumab drug). On days 1 and 8, 1 mg of OVA and aluminum hydroxide in sterile phosphate-buffered saline (PBS) were intraperitoneally injected to rats in groups 2 and 3. The control group was only subject to intraperitoneal injection of saline on days 1 and 8. One week after the last injection, the rats (groups 2 and 3) were exposed to OVA inhalation for 30 min at 2-day intervals from days 15 to 25. After sensitization and challenge with OVA, the OVA + Bmab group (group 3) were treated with a 5 mg/kg bevacizumab drug. Genes and protein expression of IL-1β and TNF-α and the expression of vascular endothelial growth factor (VEGF) protein were assessed by real-time PCR and immunohistochemistry respectively, in lung tissue. OVA exposure increased mucosal secretion and inflammatory cell populations in lung tissue and OVA-specific IgE level in serum. Also, VEGF and cytokine factor expression were significantly elevated in the OVA-induced asthma model (p ≤ 0.05). However, rats in OVA + Bmab group showed significantly a decrease in VEGF and IL-1β and TNF-α genes as well as proteins (p ≤ 0.05). The results showed that bevacizumab efficiently diminished bronchial inflammation via downregulation of VEGF expression, followed by inflammatory cells population and cytokines reduction. Angiogenesis inhibition in rats with induced asthma not only suppresses the inflammatory process through blocking VEGF expression but also inhibits the development of new blood vessels and progressing asthmatic attacks.

Alleviation of acute pancreatitis-associated lung injury by inhibiting the p38 mitogen-activated protein kinase pathway in pulmonary microvascular endothelial cells

BACKGROUND

Previous reports have suggested that the p38 mitogen-activated protein kinase signaling pathway is involved in the development of severe acute pancreatitis (SAP)-related acute lung injury (ALI). Inhibition of p38 by SB203580 blocked the inflammatory responses in SAP-ALI. However, the precise mechanism associated with p38 is unclear, particularly in pulmonary microvascular endothelial cell (PMVEC) injury.

AIM

To determine its role in the tumor necrosis factor-alpha (TNF-α)-induced inflammation and apoptosis of PMVECs in vitro. We then conducted in vivo experiments to confirm the effect of SB203580-mediated p38 inhibition on SAP-ALI.

METHODS

In vitro, PMVEC were transfected with mitogen-activated protein kinase kinase 6 (Glu), which constitutively activates p38, and then stimulated with TNF-α. Flow cytometry and western blotting were performed to detect the cell apoptosis and inflammatory cytokine levels, respectively. In vivo, SAP-ALI was induced by 5% sodium taurocholate and three different doses of SB203580 (2.5, 5.0 or 10.0 mg/kg) were intraperitoneally injected prior to SAP induction. SAP-ALI was assessed by performing pulmonary histopathology assays, measuring myeloperoxidase activity, conducting arterial blood gas analyses and measuring TNF-α, interleukin (IL)-1β and IL-6 levels. Lung microvascular permeability was measured by determining bronchoalveolar lavage fluid protein concentration, Evans blue extravasation and ultrastructural changes in PMVECs. The apoptotic death of pulmonary cells was confirmed by performing a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling analysis and examining the Bcl2, Bax, Bim and cle-caspase3 levels. The proteins levels of P-p38, NFκB, IκB, P-signal transducer and activator of transcription-3, nuclear factor erythroid 2-related factor 2, HO-1 and Myd88 were detected in the lungs to further evaluate the potential mechanism underlying the protective effect of SB203580.

RESULTS

In vitro, mitogen-activated protein kinase (Glu) transfection resulted in higher apoptotic rates and cytokine (IL-1β and IL-6) levels in TNF-α-treated PMVECs. In vivo, SB2035080 attenuated lung histopathological injury, decreased inflammatory activity (TNF-α, IL-1β, IL-6 and myeloperoxidase) and preserved pulmonary function. Furthermore, SB203580 significantly reversed changes in the bronchoalveolar lavage fluid protein concentration, Evans blue accumulation, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cell numbers, apoptosis-related proteins (cle-caspase3, Bim and Bax) and endothelial microstructure. Moreover, SB203580 significantly reduced the pulmonary P-p38, NFκB, P-signal transducer and activator of transcription-3 and Myd88 levels but increased the IκB and HO-1 levels.

CONCLUSION

p38 inhibition may protect against SAP-ALI by alleviating inflammation and the apoptotic death of PMVECs.

In Sickness and in Health: The Immunological Roles of the Lymphatic System

The lymphatic system plays crucial roles in immunity far beyond those of simply providing conduits for leukocytes and antigens in lymph fluid. Endothelial cells within this vasculature are distinct and highly specialized to perform roles based upon their location. Afferent lymphatic capillaries have unique intercellular junctions for efficient uptake of fluid and macromolecules, while expressing chemotactic and adhesion molecules that permit selective trafficking of specific immune cell subsets. Moreover, in response to events within peripheral tissue such as inflammation or infection, soluble factors from lymphatic endothelial cells exert “remote control” to modulate leukocyte migration across high endothelial venules from the blood to lymph nodes draining the tissue. These immune hubs are highly organized and perfectly arrayed to survey antigens from peripheral tissue while optimizing encounters between antigen-presenting cells and cognate lymphocytes. Furthermore, subsets of lymphatic endothelial cells exhibit differences in gene expression relating to specific functions and locality within the lymph node, facilitating both innate and acquired immune responses through antigen presentation, lymph node remodeling and regulation of leukocyte entry and exit. This review details the immune cell subsets in afferent and efferent lymph, and explores the mechanisms by which endothelial cells of the lymphatic system regulate such trafficking, for immune surveillance and tolerance during steady-state conditions, and in response to infection, acute and chronic inflammation, and subsequent resolution.

S100A8 and S100A9 Are Important for Postnatal Development of Gut Microbiota and Immune System in Mice and Infants

BACKGROUND & AIMS

After birth, the immune system matures via interactions with microbes in the gut. The S100 calcium binding proteins S100A8 and S100A9, and their extracellular complex form, S100A8-A9, are found in high amounts in human breast milk. We studied levels of S100A8-A9 in fecal samples (also called fecal calprotectin) from newborns and during infancy, and their effects on development of the intestinal microbiota and mucosal immune system.

METHODS

We collected stool samples (n = 517) from full-term (n = 72) and preterm infants (n = 49) at different timepoints over the first year of life (days 1, 3, 10, 30, 90, 180, and 360). We measured levels of S100A8-A9 by enzyme-linked immunosorbent assay and analyzed fecal microbiomes by 16S sRNA gene sequencing. We also obtained small and large intestine biopsies from 8 adults and 10 newborn infants without inflammatory bowel diseases (controls) and 8 infants with necrotizing enterocolitis and measured levels of S100A8 by immunofluorescence microscopy. Children were followed for 2.5 years and anthropometric data and medical information on infections were collected. We performed studies with newborn C57BL/6J wild-type and S100a9^-/- mice (which also lack S100A8). Some mice were fed or given intraperitoneal injections of S100A8 or subcutaneous injections of Staphylococcus aureus. Blood and intestine, mesenterial and celiac lymph nodes were collected; cells and cytokines were measured by flow cytometry and studied in cell culture assays. Colon contents from mice were analyzed by culture-based microbiology assays.

RESULTS

Loss of S100A8 and S100A9 in mice altered the phenotypes of colonic lamina propria macrophages, compared with wild-type mice. Intestinal tissues from neonatal S100-knockout mice had reduced levels of CX3CR1 protein, and Il10 and Tgfb1 mRNAs, compared with wild-type mice, and fewer T-regulatory cells. S100-knockout mice weighed 21% more than wild-type mice at age 8 weeks and a higher proportion developed fatal sepsis during the neonatal period. S100-knockout mice had alterations in their fecal microbiomes, with higher abundance of Enterobacteriaceae. Feeding mice S100 at birth prevented the expansion of Enterobacteriaceae, increased numbers of T-regulatory cells and levels of CX3CR1 protein and Il10 mRNA in intestine tissues, and reduced body weight and death from neonatal sepsis. Fecal samples from term infants, but not preterm infants, had significantly higher levels of S100A8-A9 during the first 3 months of life than fecal samples from adults; levels decreased to adult levels after weaning. Fecal samples from infants born by cesarean delivery had lower levels of S100A8-A9 than from infants born by vaginal delivery. S100 proteins were expressed by lamina propria macrophages in intestinal tissues from infants, at higher levels than in intestinal tissues from adults. High fecal levels of S100 proteins, from 30 days to 1 year of age, were associated with higher abundance of Actinobacteria and Bifidobacteriaceae, and lower abundance of Gammaproteobacteria-particularly opportunistic Enterobacteriaceae. A low level of S100 proteins in infants' fecal samples associated with development of sepsis and obesity by age 2 years.

CONCLUSION

S100A8 and S100A9 regulate development of the intestinal microbiota and immune system in neonates. Nutritional supplementation with these proteins might aide in development of preterm infants and prevent microbiota-associated disorders in later years.

p38 and Casein Kinase 2 Mediate Ribonuclease 1 Repression in Inflamed Human Endothelial Cells via Promoter Remodeling Through Nucleosome Remodeling and Deacetylase Complex

Vascular pathologies, such as thrombosis or atherosclerosis, are leading causes of death worldwide and are strongly associated with the dysfunction of vascular endothelial cells. In this context, the extracellular endonuclease Ribonuclease 1 (RNase1) acts as an essential protective factor in regulation and maintenance of vascular homeostasis. However, long-term inflammation causes strong repression of RNase1 expression, thereby promoting endothelial cell dysfunction. This inflammation-mediated downregulation of RNase1 in human endothelial cells is facilitated via histone deacetylase (HDAC) 2, although the underlying molecular mechanisms are still unknown. Here, we report that inhibition of c-Jun N-terminal kinase by small chemical compounds in primary human endothelial cells decreased physiological RNase1 mRNA abundance, while p38 kinase inhibition restored repressed RNase1 expression upon proinflammatory stimulation with tumor necrosis factor alpha (TNF-α) and poly I:C. Moreover, blocking of the p38 kinase- and HDAC2-associated kinase casein kinase 2 (CK2) by inhibitor as well as small interfering RNA (siRNA)-knockdown restored RNase1 expression upon inflammation of human endothelial cells. Further downstream, siRNA-knockdown of chromodomain helicase DNA binding protein (CHD) 3 and 4 of the nucleosome remodeling and deacetylase (NuRD) complex restored RNase1 repression in TNF-α treated endothelial cells implicating its role in the HDAC2-containing repressor complex involved in RNase1 repression. Finally, chromatin immunoprecipitation in primary human endothelial cells confirmed recruitment of the CHD4-containing NuRD complex and subsequent promoter remodeling via histone deacetylation at the RNASE1 promoter in a p38-dependent manner upon human endothelial cell inflammation. Altogether, our results suggest that endothelial RNase1 repression in chronic vascular inflammation is regulated by a p38 kinase-, CK2-, and NuRD complex-dependent pathway resulting in complex recruitment to the RNASE1 promoter and subsequent promoter remodeling.

PA-X protein of H5N1 avian influenza virus inhibits NF-kappaB activity, a potential mechanism for PA-X counteracting the host innate immune responses

PA-X is a fusion protein of influenza virus which plays a crucial role in modulating influenza virus-induced host innate immune response and subsequent pathogenicity. However, the potential mechanism of PA-X regulation of the host innate immune response remains largely unknown. It is well known that NF-κB signal pathway is crucial for the immediate early step of immune responses activation, while the specific role of PA-X in NF-κB transcriptional activity is totally unknown. In this study, we initially showed that PA-X inhibits NF-κB transcription that stimulated by poly(I:C). We then further determined that the inhibitory effect on NF-κB activation mediated by PA-X was characterized by restricting NF-κB p65 nuclear translocation and nuclear NF-κB p65 activity but not by impeding the phosphorylation of NF-κB p65. Correspondingly, PA-X decreases the amount of NF-κB signaling pathway-associated genes, including TNF-α, Nos2, IL-6 and IL-2. Moreover, PA-X also suppresses both the mRNA and protein expression level of IFN-β, suggesting the direct contribution of PA-X to the inhibition of NF-κB-regulated IFN-β expression. Together, our study sheds light on the potential molecular mechanisms underlying the regulation of host NF-κB activity by PA-X and also identifies a novel functional role for PA-X in counteracting the host innate immune response. However, further exploration of the more elaborate mechanism of PA-X-mediated inhibition of NF-κB activity and the associated signaling pathway may help to elucidate its precise mechanism of evading and subverting the host immune response.

Impairment of hypoxia-induced angiogenesis by LDL involves a HIF-centered signaling network linking inflammatory TNFα and angiogenic VEGF

Hypoxia inducible factors (HIFs) mediate angiogenesis via up-regulation of various pro-angiogenic factors (particularly VEGF) in response to hypoxia. Here, we report that hypoxia unexpectedly induced robust production of the pro-inflammatory factor TNFα by endothelial cells (ECs), suggesting an autocrine loop that in turn activated HIFs via an NF-κB-dependent process, resulting in production of VEGF and thereby promotion of angiogenesis. In contrast, low-density lipoprotein (LDL) prevented expression of HIFs in ECs exposed to either hypoxia or TNFα, while knockdown of either HIF-1α or HIF-2α strikingly attenuated hypoxia-induced production of VEGF by ECs as well as EC colony formation and tube formation. Significantly, LDL attenuated hypoxia-induced angiogenesis by disrupting the TNFα/NF-κB/HIF/VEGF signaling cascade via down-regulation of the TNF receptor TNF-R1, rather than TNFα itself, and multiple key components of both canonical and non-canonical NF-κB pathways. By doing so, LDL was able to either inhibit or down-regulate a wide spectrum of HIF-dependent pro-angiogenic downstream targets and signals. Together, these findings argue existence of a self-regulatory TNFα/NF-κB/HIF/VEGF signaling network in ECs, which mediates and fine-tones angiogenesis, at least in response to hypoxia. They also suggest that LDL impairs angiogenesis by disrupting this network, which might represent a novel mechanism underlying anti-angiogenic property of LDL.

Low-dose ionizing radiation exposure represses the cell cycle and protein synthesis pathways in in vitro human primary keratinocytes and U937 cell lines

The effects of the high-dose ionizing radiation used in radiotherapy have been thoroughly demonstrated in vitro and in vivo. However, the effects of low-dose ionizing radiation (LDIR) such as computed tomography-guided biopsies and X-ray fluoroscopy on skin cells remain controversial. This study investigated the molecular effects of LDIR on the human primary keratinocytes (HPKs) and U937 cells, monocytes-like cell lines. These cells were exposed to 0.1 Gray (Gy) X-ray as LDIR. The modulation of transcription was assessed using a cDNA array, and the protein expression after LDIR exposure was investigated using isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis at 24 hours. These effects were confirmed by immunoblotting analysis. The direct effects of LDIR on the U937 cells and HPKs and the bystander effects of irradiated HPKs on U937 cells were also investigated. LDIR downregulated c-Myc in both U937 cells and HPKs, and upregulated the p21^WAF1/CIP1 protein expression in U937 cells along with the activation of TGFβ and protein phosphatase 2A (PP2A). In HPKs, LDIR downregulated the mTOR signaling with repression of S6 and 4EBP1 activation. Similar changes were observed as bystander effects of LDIR. Our findings suggest that LDIR inhibits protein synthesis and induces the cytokines activation associated with inflammation via direct and bystander effects, which might recapitulate the effects of LDIR in inflammated skin structures.

High Amounts of S100-Alarmins Confer Antimicrobial Activity on Human Breast Milk Targeting Pathogens Relevant in Neonatal Sepsis

Sepsis is a leading cause of perinatal mortality worldwide. Breast milk (BM) feeding is protective against neonatal sepsis, but the molecular mechanisms remain unexplained. Despite various supplementations with potential bioactive components from BM formula feeding cannot protect from sepsis. S100-alarmins are important immunoregulators in newborns preventing excessive inflammation. At high concentrations, the S100A8/A9 protein complex also has antimicrobial properties due to its metal ion chelation capacity. To assess whether BM contains S100-alarmins that might mediate the sepsis-protective effect of BM 97 human BM samples stratified for gestational age, mode of delivery and sampling after birth were collected and analyzed. S100A8/A9 levels were massively elevated after birth (p < 0.0005). They slowly decreased during the first month of life, then reaching levels comparable to normal values in adult serum. The concentration of S100A8/A9 in BM was significantly higher after term compared with preterm birth (extremely preterm, p < 0.005; moderate preterm, p < 0.05) and after vaginal delivery compared with cesarean section (p < 0.0005). In newborn s100a9^−/− mice, enterally supplied S100-alarmins could be retrieved systemically in the plasma. To explore the antimicrobial activity against common causal pathogens of neonatal sepsis, purified S100-alarmins and unmodified as well as S100A8/A9-depleted BM were used in growth inhibition tests. The high amount of S100A8/A9 proved to be an important mediator of the antimicrobial activity of BM, especially inhibiting the growth of manganese (Mn) sensitive bacteria such as Staphylococcus aureus (p < 0.00005) and group B streptococci (p < 0.005). Depletion of S100A8/A9 significantly reduced this effect (p < 0.05, respectively). The growth of Escherichia coli was also inhibited by BM (p < 0.00005) as well as by S100A8/A9 in culture assays (p < 0.05). But its growth in BM remained unaffected by the removal of S100A8/A9 and was neither dependent on Mn suggesting that the antimicrobial effects of S100A8/A9 in BM are primarily mediated by its Mn chelating capacity. In summary, the enteral supply of bioavailable, antimicrobially active amounts of S100-alarmins might be a promising option to protect newborns at high risk from infections and sepsis.

CD40L and TNF both activate the classical NF-κB pathway, which is not required for the CD40L induced alternative pathway in endothelial cells

CD40L and TNF signal through engagement of their respective receptors, which are both members of the TNF receptor family. They use partially common signaling molecules leading, among others, to activation of the NF-κB pathway. However, whereas TNF activates the classical, CD40L has been reported to activate the alternative NF-κB pathway, leading to the anticipation that differences in the pattern of inflammatory gene expression would occur. Here, we have compared the gene expression repertoire of CD40L (CD154) and TNF stimulated HUVEC and report that unexpectedly, apart from a stronger response to TNF, no major qualitative differences could be observed. This applies for the period of up to 6 h, a time where the alternative pathway has already been activated. Analysis of the early events after receptor engagement revealed that both TNF and CD40L activate the classical NF-κB pathway, and confirm activation of the alternative by the latter. Furthermore, using genetic and pharmacological inhibition of the classical pathway we show that activation of the alternative occurs independently of the former. This reveals novel insights into NF-κB signaling by CD40L and TNF in endothelial cells.

Indoxyl sulfate (IS)-mediated immune dysfunction provokes endothelial damage in patients with end-stage renal disease (ESRD)

Progressive renal failure causes uremia-related immune dysfunction, which features a chronic inflammatory milieu. Given the central role of end-stage renal disease (ESRD)-related immune dysfunction in the pathogenesis of cardiovascular diseases (CVDs), much attention has been focused on how uremic toxins affect cellular immunity and the mechanisms underlying pathogenesis of atherosclerosis in ESRD patients. Here, we investigated the characteristics of monocytes and CD4+ T cells in ESRD patients and the immune responses induced by indoxyl sulfate (IS), a key uremic toxin, in order to explore the pathogenic effects of these cells on vascular endothelial cells. In ESRD patients, monocytes respond to IS through the aryl hydrocarbon receptor (AhR) and consequently produce increased levels of TNF-α. Upon stimulation with TNF-α, human vascular endothelial cells produce copious amounts of CX3CL1, a chemokine ligand of CX3CR1 that is highly expressed on CD4+CD28-T cells, the predominantly expanded cell type in ESRD patients. A migration assay showed that CD4+CD28- T cells were preferentially recruited by CX3CL1. Moreover, activated CD4+CD28- T cells exhibited cytotoxic capability allowing for the induction of apoptosis in HUVECs. Our findings suggest that in ESRD, IS-mediated immune dysfunction may cause vascular endothelial cell damage and thus, this toxin plays a pivotal role in the pathogenesis of CVD.

S100-alarmin-induced innate immune programming protects newborn infants from sepsis

The high risk of neonatal death from sepsis is thought to result from impaired responses by innate immune cells; however, the clinical observation of hyperinflammatory courses of neonatal sepsis contradicts this concept. Using transcriptomic, epigenetic and immunological approaches, we demonstrated that high amounts of the perinatal alarmins S100A8 and S100A9 specifically altered MyD88-dependent proinflammatory gene programs. S100 programming prevented hyperinflammatory responses without impairing pathogen defense. TRIF-adaptor-dependent regulatory genes remained unaffected by perinatal S100 programming and responded strongly to lipopolysaccharide, but were barely expressed. Steady-state expression of TRIF-dependent genes increased only gradually during the first year of life in human neonates, shifting immune regulation toward the adult phenotype. Disruption of this critical sequence of transient alarmin programming and subsequent reprogramming of regulatory pathways increased the risk of hyperinflammation and sepsis. Collectively these data suggest that neonates are characterized by a selective, transient microbial unresponsiveness that prevents harmful hyperinflammation in the delicate neonate while allowing for sufficient immunological protection.

Search for Master Regulators in Walking Cancer Pathways

In this chapter, we present an approach that allows a causal analysis of multiple "-omics" data with the help of an "upstream analysis" strategy. The goal of this approach is to identify master regulators in gene regulatory networks as potential drug targets for a pathological process. The data analysis strategy includes a state-of-the-art promoter analysis for potential transcription factor (TF)-binding sites using the TRANSFAC^® database combined with an analysis of the upstream signal transduction pathways that control the activity of these TFs. When applied to genes that are associated with a switch to a pathological process, the approach identifies potential key molecules (master regulators) that may exert major control over and maintenance of transient stability of the pathological state. We demonstrate this approach on examples of analysis of multi-omics data sets that contain transcriptomics and epigenomics data in cancer. The results of this analysis helped us to better understand the molecular mechanisms of cancer development and cancer drug resistance. Such an approach promises to be very effective for rapid and accurate identification of cancer drug targets with true potential. The upstream analysis approach is implemented as an automatic workflow in the geneXplain platform ( www.genexplain.com ) using the open-source BioUML framework ( www.biouml.org ).

Flow signaling and atherosclerosis

Atherosclerosis rarely develops in the region of arteries exposed to undisturbed flow (u-flow, unidirectional flow). Instead, atherogenesis occurs in the area exposed to disturbed flow (d-flow, multidirectional flow). Based on these general pathohistological observations, u-flow is considered to be athero-protective, while d-flow is atherogenic. The fact that u-flow and d-flow induce such clearly different biological responses in the wall of large arteries indicates that these two types of flow activate each distinct intracellular signaling cascade in vascular endothelial cells (ECs), which are directly exposed to blood flow. The ability of ECs to differentially respond to the two types of flow provides an opportunity to identify molecular events that lead to endothelial dysfunction and atherosclerosis. In this review, we will focus on various molecular events, which are differentially regulated by these two flow types. We will discuss how various kinases, ER stress, inflammasome, SUMOylation, and DNA methylation play roles in the differential flow response, endothelial dysfunction, and atherosclerosis. We will also discuss the interplay among the molecular events and how they coordinately regulate flow-dependent signaling and cellular responses. It is hoped that clear understanding of the way how the two flow types beget each unique phenotype in ECs will lead us to possible points of intervention against endothelial dysfunction and cardiovascular diseases.

In neonates S100A8/S100A9 alarmins prevent the expansion of a specific inflammatory monocyte population promoting septic shock

The high susceptibility of newborn infants to sepsis is ascribed to an immaturity of the neonatal immune system, but the molecular mechanisms remain unclear. Newborn monocytes massively release the alarmins S100A8/S100A9. In adults, these are major regulators of immunosuppressive myeloid-derived suppressor cells (MDSCs). We investigated whether S100A8/S100A9 cause an expansion of monocytic MDSCs (Mo-MDSCs) in neonates, thereby contributing to an immunocompromised state. Mo-MDSCs have been assigned to CD14⁺/human leukocyte antigen (HLA)-DR^-/low/CD33⁺ monocytes in humans and to CD11b⁺/Gr-1^int/Ly6G^-/Ly6C^hi cells in mice. We found monocytes with these phenotypes significantly expanded in their respective newborns. Functionally, however, they did not prove immunosuppressive but rather responded inflammatorily to microbial stimulation. Their expansion did not correlate with high S100A8/S100A9 levels in cord blood. Murine studies revealed an excessive expansion of CD11b⁺/Gr-1^int/Ly6G^-/Ly6C^hi monocytes in S100A9^-/- neonates compared to wild-type neonates. This strong baseline expansion was associated with hyperinflammatory responses during endotoxemia and fatal septic courses. Treating S100A9^-/- neonates directly after birth with S100A8/S100A9 alarmins prevented excessive expansion of this inflammatory monocyte population and death from septic shock. Our data suggest that a specific population of inflammatory monocytes promotes fatal courses of sepsis in neonates if its expansion is not regulated by S100A8/S100A9 alarmins.-Heinemann, A. S., Pirr, S., Fehlhaber, B., Mellinger, L., Burgmann, J., Busse, M., Ginzel, M., Friesenhagen, J., von Köckritz-Blickwede, M., Ulas, T., von Kaisenberg, C. S., Roth, J., Vogl, T., Viemann, D. In neonates S100A8/S100A9 alarmins prevent the expansion of a specific inflammatory monocyte population promoting septic shock.

Endothelial Cell Activation Is Regulated by Epidermal Growth Factor-like Domain 7 (Egfl7) during Inflammation

Activation of the blood vessel endothelium is a critical step during inflammation. Endothelial cells stimulated by pro-inflammatory cytokines play an essential part in the adhesion and extravasation of circulating leukocytes into inflamed tissues. The endothelial egfl7 gene (VE-statin) represses endothelial cell activation in tumors, and prior observations suggested that it could also participate in the regulation of endothelial cell activation during inflammation. We show here that Egfl7 expression is strongly repressed in mouse lung endothelial cells during LPS- and TNFα-induced inflammation in vivo LPS have a limited effect on Egfl7 expression by endothelial cells in vitro, whereas the pro-inflammatory cytokine TNFα strongly represses Egfl7 expression in endothelial cells. TNFα regulates the egfl7 gene promoter through regions located between -7585 and -5550 bp ahead of the main transcription start site and via an NF-κB-dependent mechanism. Conversely, Egfl7 regulates the response of endothelial cells to TNFα by restraining the induced expression of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin, resulting in a decreased adhesion of leukocytes onto endothelial cells stimulated by TNFα. Egfl7 regulates the expression of these adhesion molecules through the NF-κB and MEK/Erk pathways, in particular by preventing the proteasome-mediated degradation of IkBα both in non-activated endothelial cells and during activation. Egfl7 is thus an endogenous and constitutive repressor of blood vessel endothelial cell activation in normal and inflammatory conditions and participates in a loop of regulation of activation of these cells by pro-inflammatory cytokines.

Multi-omics "upstream analysis" of regulatory genomic regions helps identifying targets against methotrexate resistance of colon cancer

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Upstream analysis strategy for multi-omics data is proposed.

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Drug targets are predicted by search for TFBS and analysis of signaling network.

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Methotrexate resistance data include transcriptomics, proteomics and epigenomics.

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Predicted targets are: TGFalpha, IGFBP7, alpha9-integrin.

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Predicted drugs are: zardaverine, divalproex and human metabolite nicotinamide N-oxide.

We present an “upstream analysis” strategy for causal analysis of multiple “-omics” data. It analyzes promoters using the TRANSFAC database, combines it with an analysis of the upstream signal transduction pathways and identifies master regulators as potential drug targets for a pathological process. We applied this approach to a complex multi-omics data set that contains transcriptomics, proteomics and epigenomics data. We identified the following potential drug targets against induced resistance of cancer cells towards chemotherapy by methotrexate (MTX): TGFalpha, IGFBP7, alpha9-integrin, and the following chemical compounds: zardaverine and divalproex as well as human metabolites such as nicotinamide N-oxide.

The Prominent Role of P38 Mitogen-Activated Protein Kinase in Insulin-Mediated Enhancement of VCAM-1 Expression in Endothelial Cells

Insulin levels are a marker for cardiovascular events, but the link between hyperinsulinemia and atherosclerosis is poorly understood. We previously showed that insulin increases monocyte-endothelial interactions and the endothelial expression of the pro-atherogenic vascular cell adhesion molecule-1 (VCAM-1). The aim of this study is to examine molecular mechanisms involved in the effect of insulin on VCAM-1 expression. Human umbilical vein endothelial cells (HUVEC) were incubated with insulin (0–24 h) ± inhibitors of signaling pathways potentially involved. At pathophysiological concentrations (10−9-10−7 M), insulin selectively induced VCAM-1 expression. The p38mitogen activated protein(MAP) kinase inhibitors SB203580 and SB202190, and partially the c-Jun NH2-terminal kinase (JNK) inhibitor SP600127, decreased insulin effect on VCAM-1. Gene silencing by small interfering RNA significantly reduced the expression of p38MAP kinase, and this was accompanied by suppression of insulin-stimulated VCAM-1 expression. Treatment with insulin also led to the activation of NF-κB and induction of IκB-α phosphorylation, thus accounting for NF-κB translocation into the nucleus. Co-treatment of HUVEC with insulin and SB202190 strongly reverted the stimulatory effect of insulin on NF-κB activation, thus establishing a link between NF-κB activation and p38MAPkinase-mediated induction of VCAM-1 by insulin. In conclusion, pathophysiological insulin concentrations increase VCAM-1 expression and activate NF-κB. This mostly occurs through stimulation of p38MAP kinase.

Leukocytes Crossing the Endothelium: A Matter of Communication

Leukocytes cross the endothelial vessel wall in a process called transendothelial migration (TEM). The purpose of leukocyte TEM is to clear the causing agents of inflammation in underlying tissues, for example, bacteria and viruses. During TEM, endothelial cells initiate signals that attract and guide leukocytes to sites of tissue damage. Leukocytes react by attaching to these sites and signal their readiness to move back to endothelial cells. Endothelial cells in turn respond by facilitating the passage of leukocytes while retaining overall integrity. In this review, we present recent findings in the field and we have endeavored to synthesize a coherent picture of the intricate interplay between endothelial cells and leukocytes during TEM.

Synergistic actions of blocking angiopoietin-2 and tumor necrosis factor-α in suppressing remodeling of blood vessels and lymphatics in airway inflammation

Remodeling of blood vessels and lymphatics are prominent features of sustained inflammation. Angiopoietin-2 (Ang2)/Tie2 receptor signaling and tumor necrosis factor-α (TNF)/TNF receptor signaling are known to contribute to these changes in airway inflammation after Mycoplasma pulmonis infection in mice. We determined whether Ang2 and TNF are both essential for the remodeling on blood vessels and lymphatics, and thereby influence the actions of one another. Their respective contributions to the initial stage of vascular remodeling and sprouting lymphangiogenesis were examined by comparing the effects of function-blocking antibodies to Ang2 or TNF, given individually or together during the first week after infection. As indices of efficacy, vascular enlargement, endothelial leakiness, venular marker expression, pericyte changes, and lymphatic vessel sprouting were assessed. Inhibition of Ang2 or TNF alone reduced the remodeling of blood vessels and lymphatics, but inhibition of both together completely prevented these changes. Genome-wide analysis of changes in gene expression revealed synergistic actions of the antibody combination over a broad range of genes and signaling pathways involved in inflammatory responses. These findings demonstrate that Ang2 and TNF are essential and synergistic drivers of remodeling of blood vessels and lymphatics during the initial stage of inflammation after infection. Inhibition of Ang2 and TNF together results in widespread suppression of the inflammatory response.

Osmostress-induced gene expression--a model to understand how stress-activated protein kinases (SAPKs) regulate transcription

Adaptation is essential for maximizing cell survival and for cell fitness in response to sudden changes in the environment. Several aspects of cell physiology change during adaptation. Major changes in gene expression are associated with cell exposure to environmental changes, and several aspects of mRNA biogenesis appear to be targeted by signaling pathways upon stress. Exhaustive reviews have been written regarding adaptation to stress and regulation of gene expression. In this review, using osmostress in yeast as a prototypical case study, we highlight those aspects of regulation of gene induction that are general to various environmental stresses as well as mechanistic aspects that are potentially conserved from yeast to mammals.

Immunology of metal allergies

Allergic contact hypersensitivity to metal allergens is a common health concern worldwide, greatly impacting affected individuals with regard to both quality of life and their ability to work. With an estimated 15-20 % of the Western population hypersensitive to at least one metal allergen, sensitization rates for metallic haptens by far outnumber those reported for other common triggers of allergic contact dermatitis such as fragrances and rubber. Unfortunately, the prevalence of metal-induced hypersensitivity remains high despite extensive legislative efforts to ban/reduce the content of allergy-causing metals in recreational and occupational products. Recently, much progress has been made regarding the perception mechanisms underlying the inflammatory responses to this unique group of contact allergens. This review summarizes recent advances in our understanding of this enigmatic disease. Particular emphasis is put on the mechanisms of innate immune activation and T cell activation by common metal allergens such as nickel, cobalt, palladium, and chromate.

"Upstream Analysis": An Integrated Promoter-Pathway Analysis Approach to Causal Interpretation of Microarray Data

A strategy is presented that allows a causal analysis of co-expressed genes, which may be subject to common regulatory influences. A state-of-the-art promoter analysis for potential transcription factor (TF) binding sites in combination with a knowledge-based analysis of the upstream pathway that control the activity of these TFs is shown to lead to hypothetical master regulators. This strategy was implemented as a workflow in a comprehensive bioinformatic software platform. We applied this workflow to gene sets that were identified by a novel triclustering algorithm in naphthalene-induced gene expression signatures of murine liver and lung tissue. As a result, tissue-specific master regulators were identified that are known to be linked with tumorigenic and apoptotic processes. To our knowledge, this is the first time that genes of expression triclusters were used to identify upstream regulators.

17β estradiol regulates adhesion molecule expression in mesangial cells during glomerulonephritis

We showed previously that 17β estradiol (E2) led to improved survival in nephrotoxic serum induced nephritis (NTN) in male mice. In this study we determined whether E2 regulates vascular cell adhesion molecule (VCAM)-1, an adhesion molecule that is upregulated in kidney during autoimmune nephritis, in mesangial cells (MC). We show that E2 inhibited VCAM-1 up-regulation in kidneys in vivo during NTN, and in MCs upon TNFα stimulation. VCAM-1 up-regulation in MCs was controlled by the transcription factor NFκB. E2 inhibited RNA polymerase II recruitment to the VCAM-1 promoter, but not p65 recruitment. Interestingly E2 inhibited TNFα stimulated interaction between poly (ADP-ribose) polymerase-1 (PARP-1) and p65. As PARP-1 is required for VCAM-1 upregulation in MCs, our data suggest that E2 may inhibit pre-initiation complex formation at VCAM-1 promoter by inhibiting PARP-1 recruitment to p65. We propose that E2 plays an important role in regulating renal inflammation locally.

Reprogramming of monocytes by GM-CSF contributes to regulatory immune functions during intestinal inflammation

Human and murine studies showed that GM-CSF exerts beneficial effects in intestinal inflammation. To explore whether GM-CSF mediates its effects via monocytes, we analyzed effects of GM-CSF on monocytes in vitro and assessed the immunomodulatory potential of GM-CSF-activated monocytes (GMaMs) in vivo. We used microarray technology and functional assays to characterize GMaMs in vitro and used a mouse model of colitis to study GMaM functions in vivo. GM-CSF activates monocytes to increase adherence, migration, chemotaxis, and oxidative burst in vitro, and primes monocyte response to secondary microbial stimuli. In addition, GMaMs accelerate epithelial healing in vitro. Most important, in a mouse model of experimental T cell-induced colitis, GMaMs show therapeutic activity and protect mice from colitis. This is accompanied by increased production of IL-4, IL-10, and IL-13, and decreased production of IFN-γ in lamina propria mononuclear cells in vivo. Confirming this finding, GMaMs attract T cells and shape their differentiation toward Th2 by upregulating IL-4, IL-10, and IL-13 in T cells in vitro. Beneficial effects of GM-CSF in Crohn's disease may possibly be mediated through reprogramming of monocytes to simultaneously improved bacterial clearance and induction of wound healing, as well as regulation of adaptive immunity to limit excessive inflammation.

The biology of A20-binding inhibitors of NF-kappaB activation (ABINs)

The family of A20-Binding Inhibitors of NF-kappaB (ABINs) consists of three proteins, ABIN-1, ABIN-2 and ABIN-3, which were originally identified as A20-binding proteins and inhibitors of cytokines and Lipopolysaccharide (LPS) induced NF-kappaB activation. ABIN family members have limited sequence homology in a number of short regions that mediate A20-binding, ubiquitin-binding, and NF-kappaB inhibition. The functional role of A20 binding to ABINs remains unclear, although an adaptor function has been suggested. ABIN-1 and ABIN-3 expression is upregulated when cells are triggered by NF-kappaB-activating stimuli, suggesting a role for these ABINs in a negative feedback regulation of NF-kappaB signaling. Additional ABIN functions have been reported such as inhibition of TNF-induced hepatocyte apoptosis, regulation of HIV-1 replication for ABIN-1, and Tumor Progression Locus 2 (TPL-2)-mediated Extracellular signal-Regulated Kinase (ERK) activation for ABIN-2. In mice, ABIN-1 overexpression reduces allergic airway inflammation and TNF-mediated liver injury, ABIN-2 overexpression delays liver regeneration, and ABIN-3 overexpression partially protects against LPS-induced acute liver failure. Analysis of mice deficient in ABIN-1 or ABIN-2 demonstrates the important immune regulatory function of ABINs. Future studies should clarify the functional implication of the A20-ABIN interaction in supporting ABINs' mechanisms of action.

Post-transcriptional regulation of cystic fibrosis transmembrane conductance regulator expression and function by microRNAs

MicroRNAs (miRNAs) are increasingly recognized as important posttranscriptional regulators of gene expression, and changes in their actions can contribute to disease states. Little is understood regarding miRNA functions in the airway epithelium under normal or diseased conditions. We profiled miRNA expression in well-differentiated primary cultures of human cystic fibrosis (CF) and non-CF airway epithelia, and discovered that miR-509-3p and miR-494 concentrations were increased in CF epithelia. Human non-CF airway epithelia, transfected with the mimics of miR-509-3p or miR-494, showed decreased cystic fibrosis transmembrane conductance regulator (CFTR) expression, whereas their respective anti-miRs exerted the opposite effect. Interestingly, the two miRNAs acted cooperatively in regulating CFTR expression. Upon infecting non-CF airway epithelial cells with Staphylococcus aureus, or upon stimulating them with the proinflammatory cytokines TNF-α or IL-1β, we observed an increased expression of both miRNAs and a concurrent decrease in CFTR expression and function, suggesting that inflammatory mediators may regulate these miRNAs. Transfecting epithelia with anti-miRs for miR-509-3p and miR-494, or inhibiting NF-κB signaling before stimulating cells with TNFα or IL-1β, suppressed these responses, suggesting that the expression of both miRNAs was responsive to NF-κB signaling. Thus, miR-509-3p and miR-494 are dynamic regulators of CFTR abundance and function in normal, non-CF airway epithelia.

TNFα signals via p66(Shc) to induce E-Selectin, promote leukocyte transmigration and enhance permeability in human endothelial cells

Endothelial cells participate in inflammatory events leading to atherogenesis by regulating endothelial cell permeability via the expression of VE-Cadherin and β-catenin and leukocyte recruitment via the expression of E-Selectins and other adhesion molecules. The protein p66^Shc acts as a sensor/inducer of oxidative stress and may promote vascular dysfunction. The objective of this study was to investigate the role of p66^Shc in tumor necrosis factor TNFα-induced E-Selectin expression and function in human umbilical vein endothelial cells (HUVEC). Exposure of HUVEC to 50 ng/ml TNFα resulted in increased leukocyte transmigration through the endothelial monolayer and E-Selectin expression, in association with augmented phosphorylation of both p66^Shc on Ser³⁶ and the stress kinase c-Jun NH₂-terminal protein kinase (JNK)-1/2, and higher intracellular reactive oxygen species (ROS) levels. Overexpression of p66^Shc in HUVEC resulted in enhanced p66^Shc phosphorylation on Ser³⁶, increased ROS and E-Selectin levels, and amplified endothelial cell permeability and leukocyte transmigration through the HUVEC monolayer. Conversely, overexpression of a phosphorylation-defective p66^Shc protein, in which Ser³⁶ was replaced by Ala, did not augment ROS and E-Selectin levels, nor modify cell permeability or leukocyte transmigration beyond those found in wild-type cells. Moreover, siRNA-mediated silencing of p66^Shc resulted in marked reduction of E-Selectin expression and leukocyte transmigration. In conclusion, p66^Shc acts as a novel intermediate in the TNFα pathway mediating endothelial dysfunction, and its action requires JNK-dependent phosphorylation of p66^Shc on Ser³⁶.

Inhibition of p38 mitogen-activated protein kinase impairs influenza virus-induced primary and secondary host gene responses and protects mice from lethal H5N1 infection

Highly pathogenic avian influenza viruses (HPAIV) induce severe inflammation in poultry and men. One characteristic of HPAIV infections is the induction of a cytokine burst that strongly contributes to viral pathogenicity. This cell-intrinsic hypercytokinemia seems to involve hyperinduction of p38 mitogen-activated protein kinase. Here we investigate the role of p38 MAPK signaling in the antiviral response against HPAIV in mice as well as in human endothelial cells, the latter being a primary source of cytokines during systemic infections. Global gene expression profiling of HPAIV-infected endothelial cells in the presence of the p38-specific inhibitor SB 202190 revealed that inhibition of p38 MAPK leads to reduced expression of IFNβ and other cytokines after H5N1 and H7N7 infection. More than 90% of all virus-induced genes were either partially or fully dependent on p38 signaling. Moreover, promoter analysis confirmed a direct impact of p38 on the IFNβ promoter activity. Furthermore, upon treatment with IFN or conditioned media from HPAIV-infected cells, p38 controls interferon-stimulated gene expression by coregulating STAT1 by phosphorylation at serine 727. In vivo inhibition of p38 MAPK greatly diminishes virus-induced cytokine expression concomitant with reduced viral titers, thereby protecting mice from lethal infection. These observations show that p38 MAPK acts on two levels of the antiviral IFN response. Initially the kinase regulates IFN induction and, at a later stage, p38 controls IFN signaling and thereby expression of IFN-stimulated genes. Thus, inhibition of MAP kinase p38 may be an antiviral strategy that protects mice from lethal influenza by suppressing excessive cytokine expression.

Cytokine-induced changes in the gene expression profile of a human cerebral microvascular endothelial cell-line, hCMEC/D3

Background

The human cerebral microvascular endothelial cell line, hCMEC/D3, has been used extensively to model the blood–brain barrier (BBB) in vitro. Recently, we reported that cytokine-treatment induced loss of brain endothelial barrier properties. In this study, we further determined the gene expression pattern of hCMEC/D3 cells in response to activation with TNFα and IFNγ.

Findings

Using a microarray approach, we observed that expression of genes involved in the control of barrier permeability, including inter-brain endothelial junctions (e.g. claudin-5, MARVELD-2), integrin-focal adhesions complexes (e.g. integrin β1, ELMO-1) and transporter systems (e.g. ABCB1, SLC2A1), are altered by pro-inflammatory cytokines.

Conclusions

Our study shows that previously-described cytokine-induced changes in the pattern of gene expression of endothelium are reproduced in hCMEC/D3 cells, suggesting that this model is suitable to study inflammation at the BBB, while at the same time it has provided insights into novel key molecular processes that are altered in brain endothelium during neuroinflammation, such as modulation of cell-to-matrix contacts.

p38 MAPK signaling acts upstream of LIF-dependent neuroprotection during photoreceptor degeneration

In many blinding diseases of the retina, loss of function and thus severe visual impairment results from apoptotic cell death of damaged photoreceptors. In an attempt to survive, injured photoreceptors generate survival signals to induce intercellular protective mechanisms that eventually may rescue photoreceptors from entering an apoptotic death pathway. One such endogenous survival pathway is controlled by leukemia inhibitory factor (LIF), which is produced by a subset of Muller glia cells in response to photoreceptor injury. In the absence of LIF, survival components are not activated and photoreceptor degeneration is accelerated. Although LIF is a crucial factor for photoreceptor survival, the detailed mechanism of its induction in the retina has not been elucidated. Here, we show that administration of tumor necrosis factor-alpha (TNF) was sufficient to fully upregulate Lif expression in Muller cells in vitro and the retina in vivo. Increased Lif expression depended on p38 mitogen-activated protein kinase (MAPK) since inhibition of its activity abolished Lif expression in vitro and in vivo. Inhibition of p38 MAPK activity reduced the Lif expression also in the model of light-induced retinal degeneration and resulted in increased cell death in the light-exposed retina. Thus, expression of Lif in the injured retina and activation of the endogenous survival pathway involve signaling through p38 MAPK.

The chemokine CX3CL1 promotes trafficking of dendritic cells through inflamed lymphatics

Tissue inflammation is characterised by increased trafficking of antigen-loaded dendritic cells (DCs) from the periphery via afferent lymphatics to draining lymph nodes, with a resulting stimulation of ongoing immune responses. Transmigration across lymphatic endothelium constitutes the first step in this process and is known to involve the chemokine CCL21 and its receptor CCR7. However, the precise details of DC transit remain obscure and it is likely that additional chemokine-receptor pairs have roles in lymphatic vessel entry. Here, we report that the transmembrane chemokine CX3CL1 (fractalkine) is induced in inflamed lymphatic endothelium, both in vitro in TNF-α-treated human dermal lymphatic endothelial cells (HDLECs) and in vivo in a mouse model of skin hypersensitivity. However, unlike blood endothelial cells, which express predominantly transmembrane CX3CL1 as a leukocyte adhesion molecule, HDLECs shed virtually all CX3CL1 at their basolateral surface through matrix metalloproteinases. We show for the first time that both recombinant soluble CX3CL1 and endogenous secreted CX3CL1 promote basolateral-to-luminal migration of DCs across HDLEC monolayers in vitro. Furthermore, we show in vivo that neutralising antibodies against CX3CL1 dramatically reduce allergen-induced trafficking of cutaneous DCs to draining lymph nodes as assessed by FITC skin painting in mice. Finally, we show that deletion of the CX3CL1 receptor in Cx3cr1^−/− DCs results in markedly delayed lymphatic trafficking in vivo and impaired translymphatic migration in vitro, thus establishing a previously unrecognised role for this atypical chemokine in regulating DC trafficking through the lymphatics.

The Rho-GEF Trio regulates a novel pro-inflammatory pathway through the transcription factor Ets2

Inflammation is characterized by endothelium that highly expresses numerous adhesion molecules to trigger leukocyte extravasation. Central to this event is increased gene transcription. Small Rho-GTPases not only control the actin cytoskeleton, but are also implicated in gene regulation. However, in inflammation, it is not clear how this is regulated. Here, we show that the guanine-nucleotide exchange factor Trio expression is increased upon inflammatory stimuli in endothelium. Additionally, increased Trio expression was found in the vessel wall of rheumatoid arthritis patients. Trio silencing impaired VCAM-1 expression. Finally, we excluded that Trio-controlled VCAM-1 expression used the classical NFκB or MAP-kinase pathways, but rather acts on the transcriptional level by increasing phosphorylation and nuclear translocalization of Ets2. These data implicate Trio in regulating inflammation and provide novel targets for therapeutic purposes to treat inflammatory diseases such as rheumatoid arthritis.

Highly pathogenic influenza viruses inhibit inflammatory response in monocytes via activation of rar-related orphan receptor RORα

Infections with highly pathogenic avian influenza viruses (HPAIV) in humans lead to systemic disease associated with cytokine storm and multiorgan failure. In this study we aimed to identify the role of monocytes for the host response to HPAIV infection. Using genome-wide microarray analysis, we surprisingly demonstrate a reduced immune response of human monocytes to HPAIV H5N1 compared to human influenza A viruses. In bioinformatic analyses we could reveal a potential role of the Rar-related orphan receptor alpha (RORα) for the gene expression pattern induced by H5N1. RORα is known as an inhibitor of NF-κB signaling. We provide evidence that in monocytes RORα is activated by H5N1, resulting in inhibited NF-κB signaling. Using murine Hoxb8-immortalized RORα⁻/⁻, monocytes rescued NF-κB signaling upon H5N1 infection, confirming the biological relevance of RORα as an H5N1-induced mediator of monocytic immunosuppression. In summary, our study reveals a novel RORα-dependent escape mechanism by which H5N1 prevents an effective inflammatory response of monocytes blocking NF-κB-dependent gene expression.

Wheat resistome in response to barley yellow dwarf virus infection

Barley yellow dwarf virus (BYDV) caused one of the most serious virus diseases of wheat (Triticum aestivum) worldwide. The wheat-Thinopyrum intermedium translocation line YW642 carries BYDV resistance gene Bdv2. To explore resistant wheat resistome in response to BYDV infection, we used Affymetrix GeneChip® Wheat Genome Arrays to analyze transcriptomes of YW642 and its susceptible parent Zhong8601 at 12 and 72 h postinoculation with BYDV compared to mock-inoculated controls. Relative to mock-inoculated control, 335 defense-related transcripts were upregulated in BYDV-inoculated YW642, among which 70 were upregulated only in BYDV-inoculated YW642 but not in BYDV-inoculated Zhong8601 through clustering analysis. Additional analysis using BYDV-inoculated Zhong8601 as reference revealed that 59 defense-related transcripts were upregulated in BYDV-inoculated YW642. Comparison of these upregulated defense transcripts obtained via the two analysis ways indicated that 19 overlapped defense-related transcripts were highly expressed in BYDV-inoculated YW642 relative to BYDV-inoculated Zhong8601 and mock-inoculated YW642, which likely are significant factors in Bdv2-mediated defense response to BYDV. High expression of some resistance homologous genes, pathogen-associated molecular pattern-triggered immunity-related genes, ABC transporter genes, pathogenesis-related protein genes, and genes in reactive oxygen species, phospholipid signaling, and jasmonic acid-signaling may contribute to Bdv2-mediated defense response to BYDV.

Influenza A virus-encoded NS1 virulence factor protein inhibits innate immune response by targeting IKK

The IKK/NF-κB pathway is an essential signalling process initiated by the cell as a defence against viral infection like influenza virus. This pathway is therefore a prime target for viruses attempting to counteract the host response to infection. Here, we report that the influenza A virus NS1 protein specifically inhibits IKK-mediated NF-κB activation and production of the NF-κB induced antiviral genes by physically interacting with IKK through the C-terminal effector domain. The interaction between NS1 and IKKα/IKKβ affects their phosphorylation function in both the cytoplasm and nucleus. In the cytoplasm, NS1 not only blocks IKKβ-mediated phosphorylation and degradation of IκBα in the classical pathway but also suppresses IKKα-mediated processing of p100 to p52 in the alternative pathway, which leads to the inhibition of nuclear translocation of NF-κB and the subsequent expression of downstream NF-κB target genes. In the nucleus, NS1 impairs IKK-mediated phosphorylation of histone H3 Ser 10 that is critical to induce rapid expression of NF-κB target genes. These results reveal a new mechanism by which influenza A virus NS1 protein counteracts host NF-κB-mediated antiviral response through the disruption of IKK function. In this way, NS1 diminishes antiviral responses to infection and, in turn, enhances viral pathogenesis.

Staphylococcus aureus Panton-Valentine leukocidin induces an inflammatory response in human phagocytes via the NLRP3 inflammasome

The Staphylococcus aureus pore-forming toxin PVL is most likely causative for life-threatening necrotizing infections, which are characterized by massive tissue inflammation and necrosis. Whereas the cytotoxic action of PVL on human neutrophils is already well established, the PVL effects on other sensitive cell types, such as monocytes and macrophages, are less clear. In this study, we used different types of human leukocytes (neutrophils, monocytes, macrophages, lymphocytes) to investigate cell-specific binding of PVL subunits and subsequent proinflammatory and cytotoxic effects. In all PVL-sensitive cells, we identified the binding of the subunit LukS-PV as the critical factor for PVL-induced cytotoxicity, which was followed by binding of LukF-PV. LukS-PV binds to monocytes, macrophages, and neutrophils but not to lymphocytes. Additionally, we showed that PVL binding to monocytes and macrophages leads to release of caspase-1-dependent proinflammatory cytokines IL-1β and IL-18. PVL activates the NLRP3 inflammasome, a signaling complex of myeloid cells that is involved in caspase-1-dependent IL-1β processing in response to pathogens and endogenous danger signals. Specific inhibition of this pathway at several steps significantly reduced inflammasome activation and subsequent pyronecrosis. Furthermore, we found that PAMPs and DAMPs derived from dying neutrophils can dramatically enhance this response by up-regulating pro-IL-1β in monocytes/macrophages. This study analyzes a specific host signaling pathway that mediates PVL-induced inflammation and cytotoxicity, which has high relevance for CA-MRSA-associated and PVL-mediated pathogenic processes, such as necrotizing infections.

Human adipose tissue-derived multilineage progenitor cells exposed to oxidative stress induce neurite outgrowth in PC12 cells through p38 MAPK signaling

Background

Adipose tissues contain populations of pluripotent mesenchymal stem cells that also secrete various cytokines and growth factors to support repair of damaged tissues. In this study, we examined the role of oxidative stress on human adipose-derived multilineage progenitor cells (hADMPCs) in neurite outgrowth in cells of the rat pheochromocytoma cell line (PC12).

Results

We found that glutathione depletion in hADMPCs, caused by treatment with buthionine sulfoximine (BSO), resulted in the promotion of neurite outgrowth in PC12 cells through upregulation of bone morphogenetic protein 2 (BMP2) and fibroblast growth factor 2 (FGF2) transcription in, and secretion from, hADMPCs. Addition of N-acetylcysteine, a precursor of the intracellular antioxidant glutathione, suppressed the BSO-mediated upregulation of BMP2 and FGF2. Moreover, BSO treatment caused phosphorylation of p38 MAPK in hADMPCs. Inhibition of p38 MAPK was sufficient to suppress BMP2 and FGF2 expression, while this expression was significantly upregulated by overexpression of a constitutively active form of MKK6, which is an upstream molecule from p38 MAPK.

Conclusions

Our results clearly suggest that glutathione depletion, followed by accumulation of reactive oxygen species, stimulates the activation of p38 MAPK and subsequent expression of BMP2 and FGF2 in hADMPCs. Thus, transplantation of hADMPCs into neurodegenerative lesions such as stroke and Parkinson’s disease, in which the transplanted hADMPCs are exposed to oxidative stress, can be the basis for simple and safe therapies.