Kationisten antimikrobipeptidien aiheuttamat stressivasteet Gram-positiivisissa bakteereissa

As the resistance of bacteria to conventional antibiotics has become an increasing problem, new antimicrobial drugs are urgently needed. One possible source of new antibacterial agents is a group of cationic antimicrobial peptides (CAMPs) produced by practically all living organisms. These peptides are typically small, amphipathic and positively charged and contain well defined a-helical or b-sheet secondary structures. The main antibacterial action mechanism of CAMPs is considered to be disruption of the cell membrane, but other targets of CAMPs also exist. Some bacterial species have evolved defence mechanisms against the harmful effects of CAMPs. One of the most effective defence mechanisms is reduction of the net negative charge of bacterial cell surfaces. Global analysis of gene expression of two Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, was used to further study the stress responses induced by different types of CAMPs. B. subtilis cells were treated with sublethal concentrations of a-helical peptide LL-37, b-sheet peptide protegrin 1 or synthetic analogue poly-L-lysine, and the changes in gene expression were studied using DNA macroarrays. In the case of S. aureus, three different a-helical peptides were selected for the transcriptome analyses: temporin L, ovispirin-1 and dermaseptin K4-S4(1-16). Transcriptional changes caused by peptide stress were examined using oligo DNA microarrays. The transcriptome analysis revealed two main cell signalling mechanisms mediating CAMP stress responses in Gram-positive bacteria: extracytoplasmic function (ECF)sigma factors and two-component systems (TCSs). In B. subtilis, ECF sigma factors sigW and sigM as well as TCS LiaRS responded to the cell membrane disruption caused by CAMPs. In S. aureus, CAMPs caused a similar stress response to antibiotics interfering in cell wall synthesis, and TCS VraSR was strongly activated. All of these transcriptional regulators are known to respond to several compounds other than CAMPs interfering with cell envelope integrity, suggesting that they sense cell envelope stress in general. Among the most strongly induced genes were yxdLM (in B. subtilis) and vraDE (in S. aureus) encoding homologous ABC transporters. Transcription of yxdLM and vraDE operons is controlled by TCSs YxdJK and ApsRS, respectively. These TCSs seemed to be responsible for the direct recognition of CAMPs. The yxdLM operon was specifically induced by LL-37, but its role in CAMP resistance remained unclear. VraDE was proven to be a bacitracin transporter. We also showed that the net positive charge of the cell wall affects the signalrecognition of different TCSs responding to cell envelope stress. Inactivation of the Dlt system responsible for the D-alanylation of teichoic acids had a strong and differential effect on the activity of the studied TCSs, depending on their functional role in cells and the stimuli they sense.Tauteja aiheuttavien bakteerien lisääntyvä vastustuskyky perinteisiä antibiootteja vastaan on kasvava ongelma terveydenhuollossa. Yksi potentiaalinen uusi vaihtoehto bakteeri-infektioiden hoitoon saattavat olla pienet positiivisesti varautuneet peptidit (ns. kationiset antimikrobipeptidit). Näitä peptideitä tuottavat lähes kaikki elävät organismit aina yksisoluisista eliöistä kasveihin ja eläimiin saakka osana omaa puolustusjärjestelmäänsä. Vain harvat bakteerit ovat vastustuskykyisiä kationisille antimikrobipeptideille. Poikkeuksiakin on, kuten Staphylococcus aureus – bakteeri, joka on yleisin sairaalainfektioiden aiheuttaja Suomessa. S aureus on erittäin vastustuskykyinen useimmille ihmisen tuottamille kationisille antimikrobipeptideille, minkä on ajateltu olevan yksi syy siihen, että kyseinen bakteeri pystyy valloittamaan elintilaa ihmisen iholla ja limakalvoilla ja sopivien olosuhteiden vallitessa aiheuttamaan infektion elimistössä. Tässä tutkimuksessa S. aureus- bakteerit altistettiin erilaisille kationisille antimikrobipeptideille ja pyrittiin tunnistamaan niitä bakteerigeenejä, jotka osallistuvat puolustukseen peptidejä vastaan. Tästä saattaa olla apua tulevaisuudessa uusia lääkkeitä kehitettäessä. Vertailun vuoksi tutkittiin myös toisen mikrobin, Bacillus subtilis- bakteerin, vastetta peptidialtistukseen. Toisin kuin S. aureus, B. subtilis on ihmiselle täysin vaaraton maaperän normaali bakteeri. Näitä kahta bakteeria vertaamalla voitiin selvittää onko taudinaiheuttajille kehittynyt erityisiä mekanismeja kationisten peptidien tuhoamista varten. Tulokset osoittivat, että bakteerien soluseinällä on erittäin tärkeä rooli puolustautumisessa peptidejä vastaan. Myös erityisiä mekanismeja peptidien torjuntaan on olemassa, mutta nämä ovat yleensä erikoistuneet poistamaan lähisukuisten, samassa elinympäristössä olevien bakteerien tuottamia peptidejä. Tulokset antavat viitteitä siitä, että kationisilla antimikrobipeptideillä voisi olla käyttöä infektioiden hoidossa yhdessä perinteisten antibioottien kanssa

Ientulehdus ja parodontiitti terveysriskeinä

Vertaisarvioitu.Terve suu kuuluu olennaisena osana kokonaisterveyteen. Suun tulehdukselliset sairaudet aiheuttavat ja ylläpitävät lievää tulehdusta, joka liittyy yleissairauksiin. Parodontiitissa epäsuotuisat bakteerit ja niiden virulenssitekijät leviävät muualle elimistöön etenkin verenkierron ja syljen välityksellä. Hampaiden ja ikenien hoito on tärkeää lapsuudesta lähtien niin hampaiden ja hyvän purentatoiminnan säilyttämiseksi kuin tulehduksiin liittyvien riskitekijöiden hallitsemiseksikin. Jatkuvasti lisääntyvä tutkimusnäyttö parodontiitin hoidon yleisterveydellisistä hyödyistä osoittaa, että sillä voidaan aikaansaada esimerkiksi parempi tyypin 2 diabeteksen hoitotasapaino tai matalampi verenpaine. Lääkärille näkyviä merkkejä suun tulehdussairauksista voivat olla pitkälle edennyt hammaspuutos, punoittavat ja turvonneet ikenet tai hampaisiin kertynyt plakki. Tällöin kannattaa muistuttaa potilasta säännöllisten hammaslääkärin tarkastusten tärkeydestä.Peer reviewe

Ientulehdus ja parodontiitti terveysriskinä

Peer reviewe

Periodontitis and cardiometabolic disorders : The role of lipopolysaccharide and endotoxemia

Lipopolysaccharide is a virulence factor of gram-negative bacteria with a crucial importance to the bacterial surface integrity. From the host's perspective, lipopolysaccharide plays a role in both local and systemic inflammation, activates both innate and adaptive immunity, and can trigger inflammation either directly (as a microbe-associated molecular pattern) or indirectly (by inducing the generation of nonmicrobial, danger-associated molecular patterns). Translocation of lipopolysaccharide into the circulation causes endotoxemia, which is typically measured as the biological activity of lipopolysaccharide to induce coagulation of an aqueous extract of blood cells of the assay. Apparently healthy subjects have a low circulating lipopolysaccharide activity, since it is neutralized and cleared rapidly. However, chronic endotoxemia is involved in the pathogenesis of many inflammation-driven conditions, especially cardiometabolic disorders. These include atherosclerotic cardiovascular diseases, obesity, liver diseases, diabetes, and metabolic syndrome, where endotoxemia has been recognized as a risk factor. The main source of endotoxemia is thought to be the gut microbiota. However, the oral dysbiosis in periodontitis, which is typically enriched with gram-negative bacterial species, may also contribute to endotoxemia. As endotoxemia is associated with an increased risk of cardiometabolic disorders, lipopolysaccharide could be considered as a molecular link between periodontal microbiota and cardiometabolic diseases.Peer reviewe

Common complement factor H polymorphisms are linked with periodontitis in elderly patients

Peer reviewe

Transcriptome analysis of the responses of Staphylococcus aureus to antimicrobial peptides and characterization of the roles of vraDE and vraSR in antimicrobial resistance

<p>Abstract</p> <p>Background</p> <p>Understanding how pathogens respond to antimicrobial peptides, and how this compares to currently available antibiotics, is crucial for optimizing antimicrobial therapy. <it>Staphylococcus aureus </it>has several known resistance mechanisms against human cationic antimicrobial peptides (CAMPs). Gene expression changes in <it>S. aureus </it>strain Newman exposed to linear CAMPs were analyzed by DNA microarray. Three antimicrobial peptides were used in the analysis, two are derived from frog, temporin L and dermaseptin K4-S4(1-16), and the ovispirin-1 is obtained from sheep.</p> <p>Results</p> <p>The peptides induced the VraSR cell-wall regulon and several other genes that are also up-regulated in cells treated with vancomycin and other cell wall-active antibiotics. In addition to this similarity, three genes/operons were particularly strongly induced by the peptides: <it>vraDE</it>, SA0205 and SAS016, encoding an ABC transporter, a putative membrane-bound lysostaphin-like peptidase and a small functionally unknown protein, respectively. Ovispirin-1 and dermaseptin K4-S4(1-16), which disrupt lipid bilayers by the carpet mechanism, appeared to be strong inducers of the <it>vraDE </it>operon. We show that high level induction by ovispirin-1 is dependent on the amide modification of the peptide C-terminus. This suggests that the amide group has a crucial role in the activation of the Aps (GraRS) sensory system, the regulator of <it>vraDE</it>. In contrast, temporin L, which disrupts lipid bilayers by forming pores, revealed a weaker inducer of <it>vraDE </it>despite the C-terminal amide modification. Sensitivity testing with CAMPs and other antimicrobials suggested that VraDE is a transporter dedicated to resist bacitracin. We also showed that SA0205 belongs to the VraSR regulon. Furthermore, VraSR was shown to be important for resistance against a wide range of cell wall-active antibiotics and other antimicrobial agents including the amide-modified ovispirin-1, bacitracin, teicoplanin, cefotaxime and 10 other β-lactam antibiotics, chlorpromazine, thioridazine and EGTA.</p> <p>Conclusion</p> <p>Defense against different CAMPs involves not only general signaling pathways but also CAMP-specific ones. These results suggest that CAMPs or a mixture of CAMPs could constitute a potential additive to standard antibiotic treatment.</p

Salivary Cytokine Biomarker Concentrations in Relation to Obesity and Periodontitis

Systemic low-grade inflammation is associated with obesity. Our aim was to examine the association between obesity and salivary biomarkers of periodontitis. Salivary interleukin (IL)-1-receptor antagonist (IL-1Ra), IL-6, IL-8, IL-10, and tumor necrosis factor (TNF)-α concentrations were measured from 287 non-diabetic obese (body mass index (BMI) of >35 kg/m2) individuals and 293 normal-weight (BMI of 18.5–25 kg/m2) controls. Periodontal status was defined according to a diagnostic cumulative risk score (CRS) to calculate the risk of having periodontitis (CRS I, low risk; CRS II, medium risk; CRS III, high risk). In the whole population, and especially in smokers, higher IL-8 and lower IL-10 concentrations were detected in the obese group compared to the control group, while in non-smoking participants, the obese and control groups did not differ. IL-1Ra and IL-8 concentrations were higher in those with medium or high risk (CRS II and CRS III, p < 0.001) of periodontitis, whereas IL-10 and TNF-α concentrations were lower when compared to those with low risk (CRS I). In multivariate models adjusted for periodontal status, obesity did not associate with any salivary cytokine concentration. In conclusion, salivary cytokine biomarkers are not independently associated with obesity and concentrations are dependent on periodontal status

Endotoxemia is associated with an adverse metabolic profile

Our aim was to analyze whether endotoxemia, i.e. translocation of LPS to circulation, is reflected in the serum metabolic profile in a general population and in participants with cardiometabolic disorders. We investigated three Finnish cohorts separately and in a meta-analysis (n = 7178), namely population-based FINRISK97, FinnTwin16 consisting of young adult twins, and Parogene, a random cohort of cardiac patients. Endotoxemia was determined as serum LPS activity and metabolome by an NMR platform. Potential effects of body mass index (BMI), smoking, metabolic syndrome (MetS), and coronary heart disease (CHD) status were considered. Endotoxemia was directly associated with concentrations of VLDL, IDL, LDL, and small HDL lipoproteins, VLDL particle diameter, total fatty acids (FA), glycoprotein acetyls (GlycA), aromatic and branched-chain amino acids, and Glc, and inversely associated with concentration of large HDL, diameters of LDL and HDL, as well as unsaturation degree of FAs. Some of these disadvantageous associations were significantly stronger in smokers and subjects with high BMI, but did not differ between participants with different CHD status. In participants with MetS, however, the associations of endotoxemia with FA parameters and GlycA were particularly strong. The metabolic profile in endotoxemia appears highly adverse, involving several inflammatory characters and risk factors for cardiometabolic disorders.Peer reviewe

Immunologic burden links periodontitis to acute coronary syndrome

Peer reviewe

"As protective gear began to run low, guidance on protection became looser" - Healthcare workers' perspectives on infection prevention and control during the COVID-19 pandemic

ObjectivesThe COVID-19 pandemic has posed several risk factors to healthcare workers' (HCWs') emotional distress. The purpose of the study was to enhance understanding of the experiences and feelings of HCWs during the COVID-19 pandemic, with specific reference to infection prevention and control (IPC) practices and guidance, focusing on the quality and availability of personal protective equipment (PPE), guidelines, and management. With a qualitative approach, we aimed to enable a wider narrative; to gain a more detailed understanding related to PPE use and identify experiences that can be overlooked in forced-choice questionnaires. MethodsAn online questionnaire was conducted among HCWs of the City of Helsinki and Helsinki University Hospital between 12.6.2020 and 5.4.2021. Altogether 1,580 HCWs participated in the study, from whom 579 shared 1,666 free-text responses. These responses were analyzed qualitatively, and the results were combined with statistical data on the participants' working conditions and backgrounds. ResultsWe identified problems in PPE availability and changing guidelines as factors causing the most distress in the participants. Regarding availability, running out of masks and respirators emerged as the most worrying issue, and inadequate PPE was associated with the excessive workload (OR 1.51, CI 95% 1.01-2.25). The results also highlight the importance of transparent and clear communication regarding IPC instructions and guidance, and clear IPC guidance was associated with better levels of reported recovery from work (OR 1.51, CI 95% 1.06-2.14). ConclusionsOur study highlights the importance of adequate PPE provision, transparent communication, clear guidance, and supportive supervisory work in this ongoing pandemic and potential new ones. We suggest more rigorous preparation, with crisis communication planning and emergency storage of PPE.Peer reviewe