Modulation of lipid mediator pathways by Staphylococcus aureus in human macrophages

Staphylococcus aureus (S. aureus) causes serious infectious diseases. To develop new treatments against S. aureus infections in-depth knowledge of S. aureus-host interactions is required. The modulation of lipid mediator (LM) pathways by S. aureus remained largely unexplored so far. We show that S. aureus modulates LM formation in a model of osteomyelitis in vivo as well as in osteoclasts and monocyte-derived macrophages (MDM) in vitro. In both murine osteoclasts and human MDM S. aureus exposure caused an elevation of cyclooxygenase (COX)-2 and microsomal prostaglandin E synthase-1 (mPGES-1) expression along with increased prostaglandin E2 formation. In human MDM challenged with S. aureus during polarization, the expression of 15-lipoxygenase (LOX)-1 was prevented, which resulted in impaired formation of 15 LOX-derived LMs. The S. aureus challenge increased the expression of M1 surface markers, while it reduced M2 surface marker expression, indicating that S. aureus shifts M2- towards M1-like MDM. Our results suggest that lipoteichoic acid (LTA) largely accounts for the S. aureus-induced LM pathway modulation. We show that the induction of COX 2 and mPGES 1 expression by LTA is mediated via signaling pathways involving mainly NF κB and p38 MAPK. Impairment of 15-LOX-1 expression by LTA correlates to reduced Lamtor1 expression. We report that S. aureus even alters established phenotypes of fully polarized M1 and M2. Besides, we uncover that the SCV strain JB1 releases less LTA during growth than the wild-type strain 6850, whereas both strains contain comparable amounts of LTA. Our data suggest that COX-derived LMs may promote the survival of S. aureus. Finally, we present that strain JB1 scarcely elicits LM formation in MDM upon short-term exposure. Together, this thesis reveals how LM pathways are modulated by S. aureus. Our data add to the characterization of S. aureus SCVs. Thereby, our findings advance the current knowledge on S. aureus-host interactions

A versatile transcription factor: Multiple roles of orthopedia a (otpa) beyond its restricted localization in dopaminergic systems of developing and adult zebrafish (Danio rerio) brains

Many transcription factors boost neural development and differentiation in specific directions and serve for identifying similar or homologous structures across species. The expression of Orthopedia (Otp) is critical for the development of certain cell groups along the vertebrate neuraxis, for example, the medial amygdala or hypothalamic neurosecretory neurons. Therefore, the primary focus of the present study is the distribution of Orthopedia a (Otpa) in the larval and adult zebrafish (Danio rerio) brain. Since Otpa is also critical for the development of zebrafish basal diencephalic dopaminergic cells, colocalization of Otpa with the catecholamine synthesizing enzyme tyrosine hydroxylase (TH) is studied. Cellular colocalization of Otpa and dopamine is only seen in magnocellular neurons of the periventricular posterior tubercular nucleus and in the posterior tuberal nucleus. Otpa-positive cells occur in many additional structures along the zebrafish neuraxis, from the secondary prosencephalon down to the hindbrain. Furthermore, Otpa expression is studied in shh-GFP and islet1-GFP transgenic zebrafish. Otpa-positive cells only express shh in dopaminergic magnocellular periventricular posterior tubercular cells, and only colocalize with islet1-GFP in the ventral zone and prerecess caudal periventricular hypothalamic zone and the perilemniscal nucleus. The scarcity of cellular colocalization of Otpa in islet1-GFP cells indicates that the Shh-islet1 neurogenetic pathway is not active in most Otpa-expressing domains. Our analysis reveals detailed correspondences between mouse and zebrafish forebrain territories including the zebrafish intermediate nucleus of the ventral telencephalon and the mouse medial amygdala. The zebrafish preoptic Otpa-positive domain represents the neuropeptidergic supraopto-paraventricular region of all tetrapods. Otpa domains in the zebrafish basal plate hypothalamus suggest that the ventral periventricular hypothalamic zone corresponds to the otp-expressing basal hypothalamic tuberal field in the mouse. Furthermore, the mouse otp domain in the mammillary hypothalamus compares partly to our Otpa-positive domain in the prerecess caudal periventricular hypothalamic zone (Hc-a)

Fully Reconfigurable Bandpass with Continuously Tunable Center Frequency and Bandwidth Featuring a Constant Filter Characteristic

This work presents a reconfigurable microstrip bandpass filter with fully controllable external, inter-resonator couplings and resonators. This enables an independent tunable center frequency and bandwidth, featuring a constant filter characteristic over the entire tuning range. A cross-coupling is used to introduce a symmetric pair of transmission zeros to increase the selectivity. The resonance frequency of each split-ring resonator can be tuned by varactors, which increase the electrical length by providing additional capacitance. The couplings between the resonators are influenced by additional varactors to tune the bandwidth. The presented filter is designed for a center frequency tuning range from 1.535 GHz to 1.755 GHz with a constant absolute bandwidth, which results in a center frequency tunability of 12.5 . The bandwidth tuning peaks at 1.7 GHz with a range between 60MHz to 138MHz

Incidence and severity of G6PI-induced arthritis are not increased in genetically distinct mouse strains upon aging

Background!#!The incidence of rheumatoid arthritis is correlated with age. In this study, we analyzed the association of the incidence and severity of glucose-6-phosphate isomerase (G6PI)-induced arthritis with age in two different mouse strains.!##!Methods!#!Young and very old mice from two different arthritis-susceptible wild-type mouse strains were analyzed after a single subcutaneous injection of G6PI s.c. The metabolism and the function of synoviocytes were analyzed in vitro, the production of bioactive lipid mediators by myeloid cells and synoviocytes was assessed in vitro and ex vivo by UPLC-MS-MS, and flow cytometry was used to verify age-related changes of immune cell composition and function.!##!Results!#!While the severity of arthritis was independent from age, the onset was delayed in old mice. Old mice showed common signs of immune aging like thymic atrophy associated with decreased CD4!##!Conclusion!#!While old mice show a higher baseline of inflammatory functions, this does not result in increased reaction towards self-antigens in arthritis-susceptible mouse strains. Together, our data from two different mouse strains show that the susceptibility for G6PI-induced arthritis is not age-dependent

Staphylococcus aureus controls eicosanoid and specialized pro-resolving mediator production via lipoteichoic acid

Staphylococcus aureus causes severe infections associated with inflammation, such as sepsis or osteomyelitis. Inflammatory processes are regulated by distinct lipid mediators (LMs) but how their biosynthetic pathways are orchestrated in S. aureus infections is elusive. We show that S. aureus strikingly not only modulates pro-inflammatory, but also inflammation-resolving LM pathways in murine osteomyelitis and osteoclasts as well as in human monocyte-derived macrophages (MDMs) with different phenotype. Targeted LM metabololipidomics using ultra-performance liquid chromatography-tandem mass spectrometry revealed massive generation of LM with distinct LM signature profiles in acute and chronic phases of S. aureus-induced murine osteomyelitis in vivo. In human MDM, S. aureus elevated cyclooxygenase-2 (COX-2) and microsomal prostaglandin E-2 synthase-1 (mPGES-1), but impaired the levels of 15-lipoxygenase-1 (15-LOX-1), with respective changes in LM signature profiles initiated by these enzymes, that is, elevated PGE(2) and impaired specialized pro-resolving mediators, along with reduced M2-like phenotypic macrophage markers. The cell wall component, lipoteichoic acid (LTA), mimicked the impact of S. aureus elevating COX-2/mPGES-1 expression via NF-kappa B and p38 MAPK signalling in MDM, while the impairment of 15-LOX-1 correlates with reduced expression of Lamtor1. In conclusion, S. aureus dictates LM pathways via LTA resulting in a shift from anti-inflammatory M2-like towards pro-inflammatory M1-like LM signature profiles

Staphylococcus aureus-Derived α-Hemolysin Evokes Generation of Specialized Pro-resolving Mediators Promoting Inflammation Resolution

Underlying mechanisms of how infectious inflammation is resolved by the host are incompletely understood. One hallmark of inflammation resolution is the activation of specialized pro-resolving mediators (SPMs) that enhance bacterial clearance and promote tissue repair. Here, we reveal alpha-hemolysin (Hla) from Staphylococcus aureus as a potent elicitor of SPMbiosynthesis in human M2-likemacrophages and in the mouse peritoneum through selective activation of host 15-lipoxygenase-1 (15-LOX-1). S. aureus-induced SPMformation in M2 is abolished upon Hla depletion or 15-LOX-1 knockdown. Isolated Hla elicits SPM formation in M2 that is reverted by inhibition of the Hla receptor ADAM10. Lipid mediators derived from Hla-treated M2 accelerate planarian tissue regeneration. Hla but not zymosan provokes substantial SPM formation in the mouse peritoneum, devoid of leukocyte infiltration and pro-inflammatory cytokine secretion. Besides harming the host, Hla may also exert beneficial functions by stimulating SPM production to promote the resolution of infectious inflammation