Porphyromonas gingivalis Produce Neutrophil Specific Chemoattractants Including Short Chain Fatty Acids

Neutrophil migration from blood to tissue-residing microbes is governed by a series of chemoattractant gradients of both endogenous and microbial origin. Periodontal disease is characterized by neutrophil accumulation in the gingival pocket, recruited by the subgingival biofilm consisting mainly of gram-negative, anaerobic and proteolytic species such as Porphyromonas gingivalis. The fact that neutrophils are the dominating cell type in the gingival pocket suggests that neutrophil-specific chemoattractants are released by subgingival bacteria, but characterization of chemoattractants released by subgingival biofilm species remains incomplete. In the present study we characterized small (< 3 kDa) soluble chemoattractants released by growing P. gingivalis, and show that these are selective for neutrophils. Most neutrophil chemoattractant receptors are expressed also by mononuclear phagocytes, the free fatty acid receptor 2 (FFAR2) being an exception. In agreement with the selective neutrophil recruitment, the chemotactic activity found in P. gingivalis supernatants was mediated in part by a mixture of short chain fatty acids (SCFAs) that are recognized by FFAR2, and other leukocytes (including monocytes) did not respond to SCFA stimulation. Although SCFAs, produced by bacterial fermentation of dietary fiber in the gut, has previously been shown to utilize FFAR2, our data demonstrate that the pronounced proteolytic metabolism employed by P. gingivalis (and likely also other subgingival biofilm bacteria associated with periodontal diseases) may result in the generation of SCFAs that attract neutrophils to the gingival pocket. This finding highlights the interaction between SCFAs and FFAR2 in the context of P. gingivalis colonization during periodontal disease, but may also have implications for other inflammatory pathologies involving proteolytic bacteria

Low-density granulocytes are related to shorter pregnancy duration but not to interferon alpha protein blood levels in systemic lupus erythematosus

BACKGROUND: An increased risk of pregnancy complications is seen in women with systemic lupus erythematosus (SLE), but the specific immunopathological drivers are still unclear. Hallmarks of SLE are granulocyte activation, type I interferon (IFN) overproduction, and autoantibodies. Here we examined whether low-density granulocytes (LDG) and granulocyte activation increase during pregnancy, and related the results to IFNα protein levels, autoantibody profile, and gestational age at birth. METHODS: Repeated blood samples were collected during pregnancy in trimesters one, two, and three from 69 women with SLE and 27 healthy pregnant women (HC). Nineteen of the SLE women were also sampled late postpartum. LDG proportions and granulocyte activation (CD62L shedding) were measured by flow cytometry. Plasma IFNα protein concentrations were quantified by single molecule array (Simoa) immune assay. Clinical data were obtained from medical records. RESULTS: Women with SLE had higher LDG proportions and increased IFNα protein levels compared to HC throughout pregnancy, but neither LDG fractions nor IFNα levels differed during pregnancy compared to postpartum in SLE. Granulocyte activation status was higher in SLE relative to HC pregnancies, and it was increased during pregnancy compared to after pregnancy in SLE. Higher LDG proportions in SLE were associated with antiphospholipid positivity but not to IFNα protein levels. Finally, higher LDG proportions in trimester three correlated independently with lower gestational age at birth in SLE. CONCLUSION: Our results suggest that SLE pregnancy results in increased peripheral granulocyte priming, and that higher LDG proportions late in pregnancy are related to shorter pregnancy duration but not to IFNα blood levels in SLE

Phenol-Soluble Modulin α Peptide Toxins from Aggressive Staphylococcus aureus Induce Rapid Formation of Neutrophil Extracellular Traps through a Reactive Oxygen Species-Independent Pathway

Neutrophils have the ability to capture and kill microbes extracellularly through the formation of neutrophil extracellular traps (NETs). These are DNA and protein structures that neutrophils release extracellularly and are believed to function as a defense mechanism against microbes. The classic NET formation process, triggered by, e.g., bacteria, fungi, or by direct stimulation of protein kinase C through phorbol myristate acetate, is an active process that takes several hours and relies on the production of reactive oxygen species (ROS) that are further modified by myeloperoxidase (MPO). We show here that NET-like structures can also be formed by neutrophils after interaction with phenol-soluble modulin α (PSMα) that are cytotoxic membrane-disturbing peptides, secreted from community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). The PSMα-induced NETs contained the typical protein markers and were able to capture microbes. The PSMα-induced NET structures were disintegrated upon prolonged exposure to DNase-positive S. aureus but not on exposure to DNase-negative Candida albicans. Opposed to classic NETosis, PSMα-triggered NET formation occurred very rapidly, independently of ROS or MPO, and was also manifest at 4°C. These data indicate that rapid NETs release may result from cytotoxic membrane disturbance by PSMα peptides, a process that may be of importance for CA-MRSA virulence

Cell death and clearance - studies of human neutrophils from blood and tissue

Neutrophils are phagocytic cells that typically migrate from circulation to tissues in order to combat microbial invasion. The journey from blood to tissue involves mobilization of intracellular organelles which results in modifications of surface markers (e.g., exposure of receptors involved in adhesion, chemotaxis and phagocytosis) that render neutrophils a primed/activated phenotype distinct from that of resting blood neutrophils. Neutrophils contain a substantial arsenal of tissue destructive factors, which could be hazardous for the environment if released in an uncontrolled fashion. Therefore, neutrophil apoptosis and clearance of the dead bodies is of outmost importance and a necessity for resolution of the inflammation. Apoptosis of neutrophils can be modulated in vitro; typically pro-inflammatory danger signals delay apoptosis. The acute phase protein serum amyloid A (SAA) delayed neutrophil apoptosis in vitro, an effect that was blocked by inhibition of the receptor P2X7. Blocking of P2X7 also inhibited prolonged survival mediated by other stimuli indicating that P2X7 is not an actual SAA receptor, but instead involved in anti-apoptotic signaling in general. Clearance of apoptotic cells can also be modulated in vitro, e.g., by opsonization. This was shown for Galectin-3 that increased the clearance of apoptotic neutrophils by monocyte-derived macrophages. Galectin-3 enhanced the proportion of macrophages that engulfed apoptotic cells but also the number of ingested neutrophils in each macrophage. Apoptosis is well studied in resting neutrophils purified from peripheral blood, but how the process is modulated in tissue neutrophils is relatively unknown. We investigated the apoptotic process in tissue neutrophils from two different inflammatory settings, skin chambers on healthy subjects and synovial fluid from patients with inflammatory arthritis. Skin chamber neutrophils were totally resistant to anti-apoptotic stimulation, which was in stark contrast to neutrophils from synovial fluid that responded well to anti-apoptotic stimulation. Also, neutrophils from skin chambers showed an activated phenotype, while neutrophils from synovial fluid surprisingly displayed a phenotype similar to that of resting blood neutrophils. Thus, the tissue neutrophils in our studies behaved fundamentally different. If this means that every inflammatory setting is unique remains to be evaluated in future studies

Once again? - How an upcoming vaccination debate is portrayed in (Swedish) media

Different kinds of vaccinations are lively discussed in media. This is not a new situation, but has been intensified with break-outs of pandemics or unexpected side effects of a vaccination, such as the swine flu vaccination. The starting point in this project is the vaccination against human papillomavirus (HPV). The virus can cause cervical cancer and the vaccination is nowadays a part of the vaccination programme in Sweden and is offered all Swedish girls. During the last year some side effects of the HPV-vaccination have been reported. The decision about the vaccination can in science education be regarded as a socio-scientific issue (SSI). A socio-scientific issue can be described ‘‘to be one which has basis in science and has a potentially large impact on society’’. These SSI’s are often reported in media. The capacity to follow and evaluate discussions about science in media is often emphasized and reported as a deficit in the scientific literacy among students. This study focus media reports in the risk society, since side effects are risks both for the society and the individual. The purpose with this study is to investigate how media reports about the vaccination against HPV. This is the first step in a larger study where the purpose is to investigate how young people deal with the vaccination discourse. A qualitative content analysis was conducted on the six largest daily newspapers in Sweden. The content analysis resulted in eight categories. The categories were facts, scientific knowledge, medical knowledge, risks, worry and alarm, emotional arguments, economy, individual versus society. Even if medical or scientific knowledge are common the media reports demonstrate a wider repertoire of arguments. For instance is emotional arguments a part of how media presents a problem. In this way the use of media reports can broaden the arguments when discussing the subject. In addition, the worries and alarms are interesting from an educational perspective, since these can be critically analysed and discussed in science education. In our presentation we will describe the categories more thoroughly to illustrate the different categories. We will also compare the categories to those texts students meet in their biology textbooks

Undervisning för krisberedskap i grundskolans tidigare år – en förstudie

Omvärldsutvecklingen, Sveriges rustning av det civila försvaret, barnrättsfrågor och att barn är särskilt utsatta i krissituationer är starka skäl till att krisberedskapsundervisning i skolans lägre årskurser bör införas. I denna rapport presenteras en förstudie med syfte att undersöka förutsättningar för undervisning för krisberedskap i skolans lägre årskurser. Rapportens inledande forskningsöversikt visar att krisberedskapsundervisning för barn stärker krismedvetenheten och krishanteringsförmågan i det omgivande samhället och att det är gynnsamt att undervisa om krisberedskap redan i tidig ålder. Undervisning som anammar elevaktiva metoder och samverkar med föräldrar och lokalsamhälle har särskilt positiva effekter på elevers lärande. Resultaten från förstudien visar att svenska kursplaner och läroböcker riktade mot årskurserna ett till sex inte ger någon explicit vägledning för undervisning om krisberedskap. Dock visar kursplane- och läroboksanalysen att befintliga skrivningar och innehållsteman ger öppningar för att inkludera undervisning om krisberedskap inom ramen för flera olika ämnen. Riskerna för att grundläggande samhällsfunktioner störs eller slås ut motiverar att ge plats åt krisberedskapsundervisning i skolan, men det är viktigt att sådan undervisning vilar på en solid grund. Därför avslutas rapporten med en rekommendation om ett kombinerat forsknings- och utvecklingsarbete där yrkesverksamma lärare, forskare och beredskapsexperter tillsammans bidrar med sin expertis i framtagandet av ett undervisningsmaterial för krisberedskap i skolans lägre årskurser. Förstudien tar tagits fram av forskare vid Karlstads universitet knutna till Centrum för forskning om samhällsrisker inom ramen för ett projekt, Krisberedskap i skolan (etapp 1), med Räddningstjänsten Karlstadsregionen som projektledare och Myndigheten för samhällsskydd och beredskap (MSB) som finansiär

One‐year survival after out‐of‐ hospital cardiac arrest: Sex‐based survival analysis in a Canadian population

Abstract Objective We investigated sex differences in 1‐year survival in a cohort of patients who survived out‐of‐hospital cardiac arrest (OHCA) to hospital discharge. We hypothesized that female sex is associated with higher 1‐year posthospital discharge survival. Methods A retrospective analysis of linked data (2011–2017) from clinical databases in British Columbia (BC) was conducted. We used Kaplan–Meier curves, stratified by sex, to display survival up to 1‐year, and the log‐rank test to test for significant sex differences. This was followed by multivariable Cox proportional hazards analysis to investigate the association between sex and 1‐year mortality. The multivariable analysis adjusted for variables known to be associated with survival, including variables related to OHCA characteristics, comorbidities, medical diagnoses, and in‐hospital interventions. Results We included 1278 hospital‐discharge survivors; 284 (22.2%) were female. Females had a lower proportion of OHCA occurring in public locations (25.7% vs. 44.0%, P < 0.001), a lower proportion with a shockable rhythm (57.7% vs. 77.4%, P < 0.001), and fewer hospital‐based acute coronary diagnoses and interventions. One‐year survival for females and males was 90.5% and 92.4%, respectively (log‐rank P = 0.31). Unadjusted (hazard ratio [HR] males vs. females 0.80, 95% confidence interval [CI] 0.51–1.24, P = 0.31) and adjusted (HR males vs. females 1.14, 95% CI 0.72–1.81, P = 0.57) models did not detect differences in 1‐year survival by sex. Conclusion Females have relatively unfavorable prehospital characteristics in OHCA and fewer hospital‐based acute coronary diagnoses and interventions. However, among survivors to hospital discharge, we found no significant difference between males and females in 1‐year survival, even after adjustment

Reactivation of Desensitized Formyl Peptide Receptors by Platelet Activating Factor: A Novel Receptor Cross Talk Mechanism Regulating Neutrophil Superoxide Anion Production

<div><p>Neutrophils express different chemoattractant receptors of importance for guiding the cells from the blood stream to sites of inflammation. These receptors communicate with one another, a cross talk manifested as hierarchical, heterologous receptor desensitization. We describe a new receptor cross talk mechanism, by which desensitized formyl peptide receptors (FPR_des) can be reactivated. FPR desensitization is induced through binding of specific FPR agonists and is reached after a short period of active signaling. The mechanism that transfers the receptor to a non-signaling desensitized state is not known, and a signaling pathway has so far not been described, that transfers FPR_des back to an active signaling state. The reactivation signal was generated by PAF stimulation of its receptor (PAFR) and the cross talk was uni-directional. LatrunculinA, an inhibitor of actin polymerization, induced a similar reactivation of FPR_des as PAF while the phosphatase inhibitor CalyculinA inhibited reactivation, suggesting a role for the actin cytoskeleton in receptor desensitization and reactivation. The activated PAFR could, however, reactivate FPR_des also when the cytoskeleton was disrupted prior to activation. The receptor cross talk model presented prophesies that the contact on the inner leaflet of the plasma membrane that blocks signaling between the G-protein and the FPR is not a point of no return; the receptor cross-talk from the PAFRs to the FPR_des initiates an actin-independent signaling pathway that turns desensitized receptors back to a signaling state. This represents a novel mechanism for amplification of neutrophil production of reactive oxygen species.</p> </div

Impact of IL-1β and the IL-1R antagonist on relapse risk and survival in AML patients undergoing immunotherapy for remission maintenance

International audienceInterleukin-1 beta (IL-1β), a pro-inflammatory cytokine, has been ascribed a role in the expansion of myeloid progenitors in acute myeloid leukemia (AML) and in promoting myeloid cell-induced suppression of lymphocyte-mediated immunity against malignant cells. This study aimed at defining the potential impact of IL-1β in the post-remission phase of AML patients receiving immunotherapy for relapse prevention in an international phase IV trial of 84 patients (ClinicalTrials.gov; NCT01347996). Consecutive serum samples were collected from AML patients in first complete remission (CR) who received cycles of relapse-preventive immunotherapy with histamine dihydrochloride (HDC) and lowdose interleukin-2 (IL-2). Low IL-1β serum levels before and after the first HDC/IL-2 treatment cycle favorably prognosticated leukemia-free survival and overall survival. Serum levels of IL-1β were significantly reduced in patients receiving HDC/IL-2. HDC also reduced the formation of IL-1β from activated human PBMCs in vitro. Additionally, high serum levels of the IL-1 receptor antagonist IL-1RA were associated with favorable outcome, and AML patients with low IL-1β along with high IL-1RA levels were strikingly protected against leukemic relapse. Our results suggest that strategies to target IL-1β might impact on relapse risk and survival in AML