Background Endovascular stents and flow diverter stents (FDS) have revolutionized the treatment of intradural aneurysms; however, the need for dual anti-platelet treatment (DAPT) limits their use and can cause additional issues. Therefore, there is a need to develop stent coatings that negate the need for DAPT. Methods Two different hydrophilic polymer coatings (HPC-I and HPC-II) were used to coat small nickel titanium plates to initially test the hydrophilic properties of these coatings when applied to nickel titanium. The plates were subsequently incubated with non-medicated whole blood from healthy volunteers for 10 min and stained with a CD61 immunofluorescent antibody that allows detection of adherent platelets. The coatings were applied to FDS wires and were again incubated with non-medicated whole blood from the same volunteers. Scanning electron microscopy was used to detect adherent platelets on the wire surface. Results The HPC-II coating (1.12 ± 0.4%) showed a significantly lower CD61 +ve cell count (p ≤ 0.001) compared to both uncoated NiTi plates (48.61 ± 7.3%) and those with the HPC-I coating (mean 40.19 ± 8.9%). Minimal adherent platelets were seen on the FDS nickel titanium wires coated with the HPC-II compared to uncoated FDS under electron microscopy. Conclusion There is a significant decrease in the number of adherent CD61 +ve platelets on nickel titanium surfaces coated with the HPC-II coating compared to uncoated surfaces. The coating can be successfully applied to the wires of flow diverters. The results of this study are promising with regard to the development of new anti-thrombogenic endovascular devices.

Background: Recent epidemiological studies have shown that growing up on a traditional farm provides protection from the development of allergic disorders such as hay fever and allergic asthma. We present experimental evidence that substances providing protection from the development of allergic diseases can be extracted from dust collected in stables of animal farms. Methods: Stable dust was collected from 30 randomly selected farms located in rural regions of the Alps (Austria, Germany and Switzerland). The dust was homogenised with glass beads and extracted with physiological sodium chloride solution. This extract was used to modulate immune response in a well established mouse model of allergic asthma. Results: Treatment of mice by inhalation of stable dust extract during sensitisation to ovalbumin inhibited the development of airway hyperresponsiveness and airway eosinophilia upon challenge, as well as the production of interleukin 5 by splenocytes and of antigen specific IgG₁ and IgE. Dust extract also suppressed the generation of human dendritic cells in vitro. The biological activity of the dust extract was not exclusively mediated by lipopolysaccharide. Conclusions: Stable dust from animal farms contains strong immune modulating substances. These substances can interfere with the development of both cellular and humoral immunity against allergens, thus suppressing allergen sensitisation, airway inflammation, and airway hyperresponsiveness in a murine model of allergic asthma.

Sphingosine‐1‐phosphate (S1P) is involved in the regulation of important cellular processes, including immune‐cell trafficking and proliferation. Altered S1P signaling is strongly associated with inflammation, cancer progression, and atherosclerosis; however, the mechanisms underlying its pathophysiologic effects are only partially understood. This study evaluated the effects of S1P in vitro and in vivo on the biosynthesis of leukotrienes (LTs), which form a class of lipid mediators involved in the pathogenesis of inflammatory diseases. Here, we report for the first time that S1P potently suppresses LT biosynthesis in Ca ²⁺ ‐ionophore–stimulated intact human neutrophils. S1P treatment resulted in intracellular Ca ²⁺ mobilization, perinuclear translocation, and finally irreversible suicide inactivation of the LT biosynthesis key enzyme 5‐lipoxygenase (5‐LO). Agonist studies and S1P receptor mRNA expression analysis provided evidence for a S1P receptor 4–mediated effect, which was confirmed by a functional knockout of S1P4 in HL60 cells. Systemic administration of S1P in wild‐type mice decreased both macrophage and neutrophil migration in the lungs in response to LPS and significantly attenuated 5‐LO product formation, whereas these effects were abrogated in 5‐LO or S1P4 knockout mice. In summary, targeting the 5‐LO pathway is an important mechanism to explain S1P‐mediated pathophysiologic effects. Furthermore, agonism at S1P4 represents a novel effective strategy in pharmacotherapy of inflammation.—Fettel, J., Kühn, B., Guillen, N. A., Sürün, D., Peters, M., Bauer, R., Angioni, C., Geisslinger, G., Schnütgen, F., Meyer zu Heringdorf, D., Werz, O., Meybohm, P., Zacharowski, K., Steinhilber, D., Roos, J., Maier, T. J. Sphingosine‐1‐phosphate (S1P) induces potent anti‐inflammatory effects in vitro and in vivo by S1P receptor 4‐mediated suppression of 5‐lipoxygenase activity. FASEB J. 33, 1711–1726 (2019). www.fasebj.org

Background: Stent-assisted coiling and extra-saccular flow diversion require dual anti-platelet therapy due to the thrombogenic properties of the implants. While both methods are widely accepted, thromboembolic complications and the detrimental effects of dual anti-platelet therapy remain a concern. Anti-thrombogenic surface coatings aim to solve both of these issues. Current developments are discussed within the framework of an actual clinical case. Case description: A 33-year-old male patient lost consciousness while doing sport and was administered 500 mg acetylsalicylic acid on site. Computed tomography revealed a massive subarachnoid haemorrhage, and digital subtraction angiography showed an aneurysm of the right middle cerebral artery. Stent-assisted coiling using a neck bridging device with a hydrophilic coating (pCONUS_HPC) was considered as an appropriate approach. Another 500 mg acetylsalicylic acid IV was given. After the single anti-platelet therapy was seen to be effective, a pCONUS_HPC was implanted, and the aneurysm sac subsequently fully occluded using coils. No thrombus formation was encountered. During the following days, 2 × 500 mg acetylsalicylic acid IV daily were required to maintain single anti-platelet therapy, monitored by frequent response testing. Follow-up digital subtraction angiography after 13 days confirmed the occlusion of the aneurysm and the patency of the middle cerebral artery. Conclusion: A variety of ways to reduce the thrombogenicity of neurovascular stents is discussed. Hydrophilic surface coatings are a valid concept to improve the haemocompatibility of neurovascular implants while avoiding the use of dual anti-platelet therapy. Phosphorylcholine and phenox hydrophilic polymer coating are currently the most promising candidates. This concept is supported by anecdotal experience. However, formalised registries and randomised trials are currently being established.

We showed previously that sensitization of mice with dendritic cells (DCs) via the airways depends on activation of these cells with LPS. Allergen-pulsed DCs that were stimulated with low doses of LPS induce a strong Th2 response in vivo. Our objective was to investigate whether airway sensitization of mice by the application of DCs with a phenotype that is able to induce Th17 cells results in increased remodeling of the airways. We generated DCs from the bone marrow of mice and pulsed them with LPS-free ovalbumin. Subsequently, cells were activated with LPS with or without ATP for inflammasome activation. The activated cells were used to sensitize mice via the airways. Intranasal instillation of DCs that were activated with 0.1 ng/ml LPS induced a Th2 response with airway eosinophilia. High doses of LPS, particularly when given in combination with ATP, led to induction of a mixed Th2/Th17 response. Interestingly, we found a correlation between IL-17A production and the remodeling of the airways. Stimulation of mouse fibroblasts with purified IL-17A protein in vitro resulted in transforming growth factor-β1 secretion and collagen transcription. Interestingly, we found enhanced secretion of transforming growth factor-β1 by fibroblasts after costimulation with IL-17A and the profibrotic factor wingless-type MMTV integration site family, member 5A (Wnt5a). We showed that an allergen-specific Th17 response in the airway is accompanied by increased airway remodeling. Furthermore, we revealed that increased remodeling is not only based on neutrophilic inflammation, but also on the direct impact of IL-17A on airway structural cells.