Dataset Information

Oral Polymorphonuclear Neutrophil Contributes to Oral Health.

ABSTRACT: Purpose of Review:Oral health is maintained in a dynamic equilibrium between the host immunity and the oral microbiome. Oral polymorphonuclear neutrophils (oPMNs) are important innate immune cells in the oral cavity. Recent Findings:The oPMNs play a co-controlling part in the maintenance of oral equilibrium. In human saliva, the oPMNs integrity is preserved, and their function remains unaffected. In general, oPMNs are in a higher state of baseline activation compared to peripheral PMNs. However, in periodontitis, the oPMNs' activation state can result in excessive release of damaging molecules in the extracellular environment. Summary:The presence of oPMNs may unwittingly negatively impact the integrity of the oral tissues. While most of the oPMN functions occur intracellularly, release of their potent active mediators into the extracellular environment may jeopardize oral homeostasis and its integrity. The dual nature of oPMNs, both beneficial and detrimental, remains a challenging and understudied topic.

SUBMITTER: Rijkschroeff P

PROVIDER: S-EPMC6244624 | biostudies-other | 2018

REPOSITORIES: biostudies-other

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Oral Polymorphonuclear Neutrophil Contributes to Oral Health.

Rijkschroeff Patrick P Loos Bruno G BG Nicu Elena A EA

Current oral health reports 20181025 4

<h4>Purpose of review</h4>Oral health is maintained in a dynamic equilibrium between the host immunity and the oral microbiome. Oral polymorphonuclear neutrophils (oPMNs) are important innate immune cells in the oral cavity.<h4>Recent findings</h4>The oPMNs play a co-controlling part in the maintenance of oral equilibrium. In human saliva, the oPMNs integrity is preserved, and their function remains unaffected. In general, oPMNs are in a higher state of baseline activation compared to peripheral ...[more]

PMID: 30524928

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Project description:Trypanosoma brucei brucei trypomastigotes are classical blood parasites of cattle, these stages might become potential targets for circulating polymorphonuclear neutrophils (PMN). We here investigated NETs extrusion and related oxygen consumption in bovine PMN exposed to motile T. b. brucei trypomastigotes in vitro. Parasite exposure induced PMN activation as detected by enhanced oxygen consumption rates (OCR), extracellular acidification rates (ECAR), and production of total and extracellular reactive oxygen species (ROS). Scanning electron microscopy (SEM) showed that co-cultivation of bovine PMN with motile trypomastigotes resulted in NETs formation within 120 min of exposure. T. b. brucei-induced NETs were confirmed by confocal microscopy demonstrating co-localization of extruded DNA with neutrophil elastase (NE) and nuclear histones. Immunofluorescence analyses demonstrated that trypomastigotes induced different phenotypes of NETs in bovine PMN, such as aggregated NETs (aggNETs), spread NETs (sprNETs), and diffuse NETs (diffNETs) with aggNETs being the most abundant ones. Furthermore, live cell 3D-holotomographic microscopy unveiled detailed morphological changes during the NETotic process. Quantification of T. b. brucei-induced NETs formation was estimated by DNA and nuclear area analysis (DANA) and confirmed enhanced NETs formation in response to trypomastigote stages. Formation of NETs does not result in a decrease of T. b. brucei viability, but a decrease of 26% in the number of motile parasites. Referring the involved signaling pathways, trypomastigote-induced NETs formation seems to be purinergic-dependent, since inhibition via NF449 treatment resulted in a significant reduction of T. b. brucei-triggered DNA extrusion. Overall, future studies will have to analyze whether the formation of aggNETs indeed plays a role in the outcome of clinical disease and bovine African trypanosomiasis-related immunopathological disorders, such as increased intravascular coagulopathy and vascular permeability, often reported to occur in this disease.

Project description:Polymorphonuclear neutrophils (PMN) are the first cellular line of antibacterial host defense. They sense pathogens through recognition of pathogen-associated molecular patterns (PAMPs) by innate pattern recognition receptors, such as Toll-like receptors (TLR). The aim of this study was to investigate whether PMN sense bacterial viability and explore which viability factor could be involved in this phenomenon. For this purpose, different functions were evaluated in isolated human PMN using live Escherichia coli (Ec) and heat-killed Ec (HK-Ec). We found that bacterial viability was indispensable to induce PMN activation, as measured by forward-scatter (FSC) increase, CD11b surface expression, chemotaxis, reactive oxygen species (ROS) generation and neutrophil extracellular trap (NET) formation. As uncapped non-polyadenylated prokaryotic mRNA has been recognized as a PAMP associated to bacterial viability by macrophages and dendritic cells, total prokaryotic RNA (pRNA) from live Ec was purified and used as a stimulus for PMN. pRNA triggered similar responses to those observed with live bacteria. No RNA could be isolated from HK-Ec, explaining the lack of effect of dead bacteria. Moreover, the supernatant of dead bacteria was able to induce PMN activation, and this was associated with the presence of pRNA in this supernatant, which is released in the killing process. The induction of bactericidal functions (ROS and NETosis) by pRNA were abolished when the supernatant of dead bacteria or isolated pRNA were treated with RNAse. Moreover, endocytosis was necessary for pRNA-induced ROS generation and NETosis, and priming was required for the induction of pRNA-induced ROS in whole blood. However, responses related to movement and degranulation (FSC increase, CD11b up-regulation, and chemotaxis) were still triggered when pRNA was digested with RNase, and were not dependent on pRNA endocytosis or PMN priming. In conclusion, our results indicate that PMN sense live bacteria through recognition of pRNA, and this sensing triggers potent bactericidal mechanisms.

Project description:Oral polymorphonuclear neutrophils (oPMNs) are essential for the maintenance of oral health. Functionally active oPMNs have been described in oral health, gingivitis and periodontitis. Interestingly, recent evidence showed that oPMNs from chronic periodontitis patients have a similar functional and reactivity pattern compared to oPMNs from healthy subjects. However, it remains unknown whether oPMNs respond to the initiation and resolution of gingival inflammation. Therefore, this study aimed to evaluate the oPMNs’ transcriptional responses during the initiation and resolution of an experimentally induced gingivitis. Oral rinses were obtained from 8 subjects at 4 different time points during the experiment for the isolation of oPMNs; day 0 (baseline), day 9 (during gingivitis challenge), day 14 (end of the challenge) and day 21 (resolution). Transcriptome of oPMNs was determined by RNAsequencing. Differentially expressed genes (DEGs) was selected at P<0.01 level, and evaluated for pathway regulation at different time points using Ingenuity Pathway Analysis suite. During the gingivitis challenge, dental plaque levels and gingival bleeding levels were significantly increased at day 14 compared to baseline. Transcriptome analysis indicate four major clusters of DEGs, which consisted of a group of 256 initial response DEGs (day 9 only), 221 late response DEGs (day 14 only), 53 persistent response DEGs (consistent at day 9 and day 14), and a group of 524 DEGs showing response only after the gingivitis challenge (day 21 only). Pathway analysis of the initial response DEGs showed their involvement in many immune regulatory pathways (interleukin signaling, reactive oxygen species processes and granulocyte adhesion and diapedesis). Late responding DEGs mainly showed activation of signaling pathways and phagosome formation as part of the phagocytosis process, whereas DEGs at day 21 were involved in epithelial adherence signaling and other miscellaneous related signaling pathways. This study showed that oPMNs have specific expression profiles during the development and resolution of experimental gingivitis. Even though, the specific observed pathways were not identical within each time point, the altered pathways indicate PMN responses in general and suggests an immunomodulatory role for the oPMNs. The oPMNs may therefore play a co-controlling part in the initiation and resolution of gingival inflammation.

Dataset Information

Oral Polymorphonuclear Neutrophil Contributes to Oral Health.

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Oral Polymorphonuclear Neutrophil Contributes to Oral Health.

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