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Blood neutrophils provide the first line of defense against pathogens but have also been implicated in thrombotic processes. This dual function of neutrophils could reflect an evolutionarily conserved association between blood coagulation and antimicrobial defense, although the molecular determinants and in vivo significance of this association remain unclear. Here we show that major microbicidal effectors of neutrophils, the serine proteases neutrophil elastase and cathepsin G, together with externalized nucleosomes, promote coagulation and intravascular thrombus growth in vivo. The serine proteases and extracellular nucleosomes enhance tissue factor- and factor XII-dependent coagulation in a process involving local proteolysis of the coagulation suppressor tissue factor pathway inhibitor. During systemic infection, activation of coagulation fosters compartmentalization of bacteria in liver microvessels and reduces bacterial invasion into tissue. In the absence of a pathogen challenge, neutrophil-derived serine proteases and nucleosomes can contribute to large-vessel thrombosis, the main trigger of myocardial infarction and stroke. The ability of coagulation to suppress pathogen dissemination indicates that microvessel thrombosis represents a physiological tool of host defense., Innate immunity represents an early defense mechanism against invading pathogens. Whereas in mammals this is complemented by adaptive immunity, host defenses in many other animal species, including arthropods--the largest phylum [...]

The ductus arteriosus (DA) is a fetal shunt vessel between the pulmonary artery and the aorta that closes promptly after birth. Failure of postnatal DA closure is a major cause of morbidity and mortality particularly in preterm neonates. The events leading to DA closure are incompletely understood. Here we show that platelets have an essential role in DA closure. Using intravital microscopy of neonatal mice, we observed that platelets are recruited to the luminal aspect of the DA during closure. DA closure is impaired in neonates with malfunctioning platelet adhesion or aggregation or with defective platelet biogenesis. Defective DA closure resulted in a left-to-right shunt with increased pulmonary perfusion, pulmonary vascular remodeling and right ventricular hypertrophy. Our findings indicate that platelets are crucial for DA closure by promoting thrombotic sealing of the constricted DA and by supporting luminal remodeling. A retrospective clinical study revealed that thrombocytopenia is an independent predictor for failure of DA closure in preterm human newborns, indicating that platelets are likely to contribute to DA closure in humans., The DA is a fetal arterial shunt vessel connecting the pulmonary artery with the aortic arch. During fetal life, the DA directs deoxygenated blood away from the pulmonary circulation and [...]

Background: Keratinocyte cancers, also referred to as non‐melanoma skin cancers (NMSCs), are one of the most common malignant skin tumors. We performed a retrospective analysis of lesions from patients of a private dermatology practice to evaluate the use of electrical impedance spectroscopy (EIS) in detecting keratinocyte malignancies. The aim of the study is to assess the accuracy of the technique and to rate its use as supportive tool in NMSC diagnosis. Material and Methods: The period evaluated ranges from September 2015 to November 2019. In total, 1712 lesions from 951 patients were included. All lesions suspicious for malignancy were gauged with the Nevisense device. Excised lesions were sent in for histopathological classification, and the results were compared to the Nevisense score. Results: A total of 767 lesions (44.8%) received a negative score (0‐3) from the Nevisense system and 945 lesions (55.2%) a positive score (4‐10). The combination of the dermatologist's visual assessment plus the technical determined Neviscore resulted in the excision of 52.5% of all 1712 suspicious lesions whereof 15% were found to be malignant. The sensitivity of Nevisense was 98.4% for NMSC detection. Conclusion: Electrical impedance spectroscopy was found to be a valuable adjunct support tool in clinical decisions for cases with suspicion for NMSC. [ABSTRACT FROM AUTHOR]

Objective: Our previous studies have suggested a role of mitogen-activated protein kinases (MAPKs) in cardioprotection in the porcine heart. To investigate, whether this could be due to modification of transcriptional events we studied the influence of actinomycin-D (act-D), a known RNA-synthesis inhibitor on (i) ischemic preconditioning, (ii) (IP)-mediated cardioprotection, (iii) transcription factors levels and MAPKs activation. Methods: The IP-design in our model included two cycles of 10′ LAD occlusion (CO) and 10′ reperfusion (RP), followed by 40′ CO (index ischemia) and 60′ RP. Act-D was infused intramyocardially (i.my.) or systemically (syst.) (0.05 or 0.12 mg/kg) during 15′ before IP and during both RP cycles of the IP-protocol. The i.my. infusions occurred via four pairs of needles into the risk area (RA). Results: Systemic infusion of act-D (0.05 mg/kg) before index ischemia significantly increased the IS from 54.0±2.5 to 78.5±3.8%. IP significantly reduced the IS to 2.5±0.8%. Syst. of act-D completely abolished the IP-induced cardioprotection. At a dose of 0.12 mg/kg the IS was 88.6±1.7% of the risk area; at 0.05 mg/kg IS was 65.6±1.5%. Local infusion of act-D reduced the IP-induced cardioprotection in a concentration dependent manner. Syst. or i.my. infusion of DMSO in KHB did not influence the IP-induced cardioprotection. Western blot analysis with phospho-specific antibodies showed a significant increase in phosphorylation of cytosolic ERK1/2 and SAPK/JNKs at the end of IP procedure and act-D treatment inhibited IP-induced activation of these MAPKs. By Western blot analysis using phospho-specific antibodies against c-Jun, ATF-2, Elk-1 and c-Myc we found increased phosphorylation of all these transcription factors in the myocardial risk area at the end of IP protocol and both local and systemic infusion of act-D significantly (P<0.05) inhibited this increased phosphorylation. Unlike UO, act-D had no influence on the Akt-pathway but inhibited the increased expression of S100 protein induced by IP. Conclusions: We demonstrate in vivo that act-D, completely cancelled the IP-induced cardioprotection. The influence of act-D on cardioprotection, transcription factors, and activities of ERKs and JNKs indicates a possible transcriptional role of these MAPKs signal transduction pathways during ischemia and in IP. [Copyright &y& Elsevier]

Millions of platelets are produced each hour by bone marrow (BM) megakaryocytes (MKs). MKs extend transendothelial proplatelet (PP) extensions into BM sinusoids and shed new platelets into the blood. The mechanisms that control platelet generation remain incompletely understood. Using conditional mutants and intravital multiphoton microscopy, we show here that the lipid mediator sphingosine 1-phosphate (S1P) serves as a critical directional cue guiding the elongation of megakaryocytic PP extensions from the interstitium into BM sinusoids and triggering the subsequent shedding of PPs into the blood. Correspondingly, mice lacking the S1P receptor S1pr1 develop severe thrombocytopenia caused by both formation of aberrant extravascular PPs and defective intravascular PP shedding. In contrast, activation of S1pr1 signaling leads to the prompt release of new platelets into the circulating blood. Collectively, our findings uncover a novel function of the S1P–S1pr1 axis as master regulator of efficient thrombopoiesis and might raise new therapeutic options for patients with thrombocytopenia.

Deep vein thrombosis (DVT) is a major cause of cardiovascular death. The sequence of events that promote DVT remains obscure, largely as a result of the lack of an appropriate rodent model. We describe a novel mouse model of DVT which reproduces a frequent trigger and resembles the time course, histological features, and clinical presentation of DVT in humans. We demonstrate by intravital two-photon and epifluorescence microscopy that blood monocytes and neutrophils crawling along and adhering to the venous endothelium provide the initiating stimulus for DVT development. Using conditional mutants and bone marrow chimeras, we show that intravascular activation of the extrinsic pathway of coagulation via tissue factor (TF) derived from myeloid leukocytes causes the extensive intraluminal fibrin formation characteristic of DVT. We demonstrate that thrombus-resident neutrophils are indispensable for subsequent DVT propagation by binding factor XII (FXII) and by supporting its activation through the release of neutrophil extracellular traps (NETs). Correspondingly, neutropenia, genetic ablation of FXII, or disintegration of NETs each confers protection against DVT amplification. Platelets associate with innate immune cells via glycoprotein Ibα and contribute to DVT progression by promoting leukocyte recruitment and stimulating neutrophil-dependent coagulation. Hence, we identified a cross talk between monocytes, neutrophils, and platelets responsible for the initiation and amplification of DVT and for inducing its unique clinical features.