Background Bloodstream infections (BSI) are the most common infectious complications in patients ... more Background Bloodstream infections (BSI) are the most common infectious complications in patients receiving allogeneic hematopoietic stem-cell transplants (allo-HSCT). Polymorphonuclear neutrophils (PMN) are quantified to monitor the susceptibility to BSIs, however, their degree of activation is not. We previously identified a population of primed PMNs (pPMN) with distinct markers of activation representing ∼10% of PMNs in the circulation. In this study, we investigate whether susceptibility to BSIs is related to the proportion of pPMN rather than strictly PMN counts. Methods In this prospective observational study, we used flow cytometry to assess pPMNs in blood and oral rinse samples collected from patients receiving an allo-HSCT over the course of their treatment. We used the proportion of pPMNs in the blood on day five post-transplant to categorize patients into a high- or a low-pPMN group (> or <10% pPMNs). These groups were then used as a predictor of BSIs. Results A tota...
This prospective cohort study aimed to investigate the impact of maternal oral inflammation on hu... more This prospective cohort study aimed to investigate the impact of maternal oral inflammation on human milk composition including neutrophil counts, activation state (based on cluster of differentiation (CD) markers expression), and fatty acid levels. Fifty mothers were recruited from St. Michael’s hospital, Toronto, and followed up from 2–4 weeks until 4 months postpartum. Oral rinse and human milk samples were collected at both timepoints. Oral polymorphonuclear neutrophils (oPMNs) within the rinses were quantified using flow cytometry and the participants’ oral health state was categorized into three groups (i.e., healthy, moderate, and severe) based on the oPMNs counts. Fatty acids were identified and quantified using a gas chromatography-flame ionization detector (GC-FID). Compared to mothers with a healthy oral health state, mothers with moderate to severe oral inflammation had a statistically significant decrease in the expression of CD64 biomarker, an increase in the expressio...
International Journal of Molecular Sciences, Aug 24, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Background and objectivesPeriodontitis affects the supporting structures of the teeth as a result... more Background and objectivesPeriodontitis affects the supporting structures of the teeth as a result of the interactions between the subgingival biofilm and the host immune system. Periodontal therapy in severe forms of periodontitis often utilizes antimicrobial agents with some potential to improve host defense responses. In the present study, we investigated the in vitro effect of metronidazole (MTZ) at concentrations achievable in the periodontal pocket on PMN activation and PMN mediated killing of Porphyromonas gingivalis.Materials and methodsFlow cytometry based assays were used to measure the impact of MTZ on PMN degranulation, neutrophil extracellular trap (NET) formation and myeloperoxidase (MPO) release and phagocytosis in response to the keystone oral pathogen P. gingivalis. Functional assays for PMN mediated killing of P. gingivalis and reactive oxygen species (ROS) production in PMN were also carried out.ResultsWe demonstrate that PMNs pretreated with MTZ (2 μg/ml or 50 μg/...
All biomaterials, when implanted in vivo, elicit cellular and tissue responses. These responses i... more All biomaterials, when implanted in vivo, elicit cellular and tissue responses. These responses include the inflammatory and wound healing responses, foreign body reactions, and fibrous encapsulation of the implanted materials. Macrophages are myeloid immune cells that are tactically situated throughout the tissues, where they ingest and degrade dead cells and foreign materials in addition to orchestrating inflammatory processes. Macrophages and their fused morphologic variants, the multinucleated giant cells, which include the foreign body giant cells (FBGCs) are the dominant early responders to biomaterial implantation and remain at biomaterial-tissue interfaces for the lifetime of the device. An essential aspect of macrophage function in the body is to mediate degradation of bio-resorbable materials including bone through extracellular degradation and phagocytosis. Biomaterial surface properties play a crucial role in modulating the foreign body reaction in the first couple of weeks following implantation. The foreign body reaction may impact biocompatibility of implantation devices and may considerably impact short-and long-term success in tissue engineering and regenerative medicine, necessitating a clear understanding of the foreign body reaction to different implantation materials. The focus of this review article is on the interactions of macrophages and foreign body giant cells with biomaterial surfaces, and the physical, chemical and morphological characteristics of biomaterial surfaces that play a role in regulating the foreign body response. Events in the foreign body response include protein adsorption, adhesion of monocytes/macrophages, fusion to form FBGCs, and the consequent modification of the biomaterial surface. The effect of physico-chemical cues on macrophages is not well known and there is a complex interplay between biomaterial properties and those that result from interactions with the local environment. By having a better understanding of the role of macrophages in the tissue healing processes, especially in events that follow biomaterial implantation, we can design novel biomaterials-based tissue-engineered constructs that elicit a favorable immune response upon implantation and perform for their intended applications.
The oral cavity hosts over 700 different microbial species that produce a rich reservoir of bioac... more The oral cavity hosts over 700 different microbial species that produce a rich reservoir of bioactive metabolites critical to oral health maintenance. Over the last two decades, new insights into the oral microbiome and its importance in health and disease have emerged mainly due to the discovery of new oral microbial species using next-generation sequencing. This advancement has revolutionized the documentation of unique microbial profiles associated with different niches and health/disease states within the oral cavity and the relation of the oral bacteria to systemic diseases. However, less work has been done to identify and characterize the unique oral microbial metabolites that play critical roles in maintaining equilibrium between the various oral microbial species and their human hosts. This article discusses the most significant microbial metabolites produced by these diverse communities of oral bacteria that can either foster health or contribute to disease. Finally, we she...
David Meiri,1 Christopher B. Marshall,1,2 Melissa A. Greeve,1 Bryan Kim,1 Marc Balan,1,2 Fernando... more David Meiri,1 Christopher B. Marshall,1,2 Melissa A. Greeve,1 Bryan Kim,1 Marc Balan,1,2 Fernando Suarez,1 Chris Bakal,1 Chuanjin Wu,1 Jose LaRose,1 Noah Fine,1,2 Mitsuhiko Ikura,1,2,* and Robert Rottapel1,2,3,4,* 1Ontario Cancer Institute and the Campbell Family Cancer Research Institute, 101 College Street, Room 8-703 Toronto Medical Discovery Tower, University of Toronto, Toronto, ON M5G 1L7, Canada 2Department of Medical Biophysics 3Departments of Medicine and Immunology University of Toronto, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada 4Division of Rheumatology, St. Michael’s Hospital, 30 Bond Street, Toronto, ON M5B 1W8, Canada *Correspondence: [email protected] (M.I.), [email protected] (R.R.) DOI 10.1016/j.molcel.2012.01.027
The presence of periodontal diseases (PDs) often strongly correlates with other severe chronic in... more The presence of periodontal diseases (PDs) often strongly correlates with other severe chronic inflammatory conditions, including cardiovascular disease, diabetes, and arthritis. However, the mechanisms through which these diseases interact are unclear. In PD, tissue and bone destruction in the mouth is driven by elevated recruitment of polymorphonuclear neutrophils (PMNs), which are primed and recruited from the circulation to sites of inflammation. We predicted that systemic effects on PMN mobilization or priming could account for the interaction between PD and other inflammatory conditions. We tested this using a mouse model of ligature-induced PD and found elevated PMN counts specifically in bone marrow, supporting a systemic effect of periodontal tissue inflammation on PMN production. In contrast, mice with induced peritonitis had elevated PMN counts in the blood, peritoneum, and colon. These elevated counts were further significantly increased when acute peritonitis was induce...
Renal ischemia reperfusion injury (IRI) is associated with inflammation, including neutrophil inf... more Renal ischemia reperfusion injury (IRI) is associated with inflammation, including neutrophil infiltration that exacerbates the initial ischemic insult. The molecular pathways involved are poorly characterized and there is currently no treatment. We performed an in silico analysis demonstrating changes in NFκB-mediated gene expression in early renal IRI. We then evaluated NFκB-blockade with a BRD4 inhibitor on neutrophil adhesion to endothelial cells in vitro, and tested BRD4 inhibition in an in vivo IRI model. BRD4 inhibition attenuated neutrophil adhesion to activated endothelial cells. In vivo, IRI led to increased expression of cytokines and adhesion molecules at 6 h post-IRI with sustained up-regulated expression to 48 h post-IRI. These effects were attenuated, in part, with BRD4 inhibition. Absolute neutrophil counts increased significantly in the bone marrow, blood, and kidney 24 h post-IRI. Activated neutrophils increased in the blood and kidney at 6 h post-IRI and remained ...
OBJECTIVES Adverse socioeconomic conditions have been suggested to "get under the skin"... more OBJECTIVES Adverse socioeconomic conditions have been suggested to "get under the skin" through eliciting a stress response that can trigger periodontal inflammation. We aimed to: (1) estimate the extent to which socioeconomic position (SEP) associates with periodontal disease (PD) and pro-inflammatory oral immunity (2) determine the contribution of psychosocial stress and stress hormones to these relationships. METHODS In this cross-sectional study (n=102), participants (20-59 years old) completed financial and perceived stress questionnaires and underwent full-mouth periodontal examinations. SEP was characterized by annual household income and educational attainment. Cortisol, a biological correlate of chronic stress, was assessed in hair samples. Oral immunity was characterized by assessing oral inflammatory load and pro-inflammatory oral neutrophil function. Blockwise Poisson and logistic regression models were applied. RESULTS Compared to lower SEP, individuals in the middle and higher income categories had a significantly lower probability of PD (IRR=0.5, 95%CI 0.3, 0.7 and IRR=0.4, 95%CI 0.2, 0.7) and OIL (IRR=0.6, 95%CI 0.3, 0.8 and IRR=0.5, 95%CI 0.3, 0.7) and were less likely to have a pro-inflammatory oral immune function (OR=0.1, 95%CI 0.0, 0.7 and OR= 0.1, 95%CI 0.0, 0.9). PD and oral immune parameters were significantly associated with financial stress and cortisol. Adjusting for financial stress and cortisol partially attenuated the socioeconomic differences in PD to IRR=0.7, 95%CI 0.5,0.8 and IRR=0.6, 95%CI 0.5,0.7 for the middle and higher income categories, respectively. Similar results were observed for pro-inflammatory immunity (OR=0.2, 95%CI 0.0,1.8 and OR=0.3, 95%CI 0.0, 2.3). CONCLUSION These findings suggest that psychosocial stress may contribute to a pro-inflammatory immunity that is implicated in PD pathobiology, and provide insight into social-to-biological processes in oral health.
Polymorphonuclear neutrophils (PMNs) are the most common leukocytes in the circulation and exhibi... more Polymorphonuclear neutrophils (PMNs) are the most common leukocytes in the circulation and exhibit a wide range of distinct cellular phenomena as part of their microbicidal killing activities, including degranulation, phagocytosis, reactive oxygen species (ROS) production, adhesion, chemotaxis and production of PMN Extracellular Traps (NETs). As a simple in vitro test of PMN functional responses in human blood we have developed a multicolor flow cytometry-based assay of PMN cluster of differentiation (CD) surface marker expression. Short incubations of whole human blood can be performed in the presence of a wide range of agonists or inhibitors, followed by sensitive detection of changes in CD marker expression. This protocol has the advantage that small amounts of human blood are necessary and there are no PMN isolation steps, which can alter PMN activation status.
Polymorphonuclear neutrophils (PMNs) are the most abundant circulating leukocytes, and the first ... more Polymorphonuclear neutrophils (PMNs) are the most abundant circulating leukocytes, and the first cells recruited to sites of tissue inflammation. Using a fixation method to preserve native CD marker expression prior to immunophenotyping, we identified a distinct population of “primed for recruitment” PMNs in healthy mouse and human blood that has high expression of adhesion and activation markers compared with the bulk resting-state PMNs. In response to acute tissue inflammation, primed PMNs (pPMNs) were rapidly depleted from the circulation and recruited to the tissue. One hour after acute peritoneal insult, pPMNs became the dominant PMN population in bone marrow (BM) and blood, returning to baseline levels with resolution of inflammation. PMN priming was induced by the granulopoietic factors granulocyte-macrophage–colony-stimulating factor (GM-CSF) and granulocyte–colony-stimulating factor (G-CSF). High levels of pPMNs were observed in neutropenic mice and in pediatric neutropenic...
Neutrophils, the most numerous leukocytes, play an important role in maintaining oral health thro... more Neutrophils, the most numerous leukocytes, play an important role in maintaining oral health through interactions with oral microbial biofilms. Both neutrophil hyperactivity and the bacterial subversion of neutrophil responses can cause inflammation-mediated tissue damage like that seen in periodontal disease.
Neutrophils play a crucial role in the immune response, leaving the circulation to participate in... more Neutrophils play a crucial role in the immune response, leaving the circulation to participate in an inflammatory response to perceived pathogens. Yet in the oral cavity, they are constantly recruited into the gingival sulcus even in health, producing no apparent clinical inflammation. It has been demonstrated that in this homeostatic state the neutrophils present a "partially active" phenotype, termed para-inflammation. To further investigate this phenotype, we studied the morphology of neutrophils obtained in vivo under transmission electron microscopy (TEM), in health and Chronic Periodontitis (CP), in the blood and the oral cavity. To study and compare the changes induced by the commensal oral bacteria in vitro, blood neutrophils were also incubated separately with S. oralis cultures. Our hypothesis was that the neutrophils in the healthy oral cavity will present a morphology consistent with para-inflammation, in contrast to the naïve phenotype of blood neutrophils, and the fully active, pro-inflammatory oral neutrophils in CP. iii Acknowledgments I would first like to express my deepest thanks and gratitude to my supervisor and mentor Dr. Michael Glogauer, for his incredible support and guidance, and for putting his faith in me. I am extremely lucky to have such knowledgeable, hardworking, and kind person as my guide. Needless to say, without him none of this would have happened. To Drs. Howard Tenenbaum and Bernhard Ganss, whose insightful guidance and comments made all the difference, thank you for steering the ship in the right direction.
Progression of inflammatory osteolytic diseases, including rheumatoid arthritis and periodontitis... more Progression of inflammatory osteolytic diseases, including rheumatoid arthritis and periodontitis, is characterized by increased production of proinflammatory mediators and matrix-degrading enzymes by macrophages and increased osteoclastic activity. Phenotypic changes in macrophages are central to the healing process in virtually all tissues. Using a murine model of periodontitis, we assessed the timing of macrophage phenotypic changes and the impact of proresolving activation during inflammatory osteolysis and healing. Proinflammatory macrophage activation and TNF-α overproduction within 3 wk after induction of periodontitis was associated with progressing bone loss. Proresolving activation within 1 wk of stimulus removal and markers of resolving macrophages (IL-10, TGF-β, and CD206) correlated strongly with bone levels. In vivo macrophage depletion with clodronate liposomes prevented bone resorption but impaired regeneration. Induction of resolving macrophages with rosiglitazone, ...
Neutrophils in circulation experience significant shear forces due to blood flow when they tether... more Neutrophils in circulation experience significant shear forces due to blood flow when they tether to the vascular endothelium. Biochemical and biophysical responses of neutrophils to the physical force of flowing blood modulate their behavior and promote tissue recruitment under pro-inflammatory conditions. Neutrophil mechanotransduction responses occur through mechanisms that are not yet fully understood. In our recent work, we showed that GEF-H1, a RhoA specific guanine nucleotide exchange factor (GEF), is required to maintain neutrophil motility and migration in response to shear stress. GEF-H1 re-localizes to flottilin-rich uropods in neutrophils in response to fluid shear stress and promotes spreading and crawling on activated endothelial cells. GEF-H1 drives cellular contractility through myosin light chain (MLC) phosphorylation downstream of the Rho-ROCK signaling axis. We propose that GEF-H1-dependent cell spreading and crawling in shear stress-dependent neutrophil recruitme...
Background Bloodstream infections (BSI) are the most common infectious complications in patients ... more Background Bloodstream infections (BSI) are the most common infectious complications in patients receiving allogeneic hematopoietic stem-cell transplants (allo-HSCT). Polymorphonuclear neutrophils (PMN) are quantified to monitor the susceptibility to BSIs, however, their degree of activation is not. We previously identified a population of primed PMNs (pPMN) with distinct markers of activation representing ∼10% of PMNs in the circulation. In this study, we investigate whether susceptibility to BSIs is related to the proportion of pPMN rather than strictly PMN counts. Methods In this prospective observational study, we used flow cytometry to assess pPMNs in blood and oral rinse samples collected from patients receiving an allo-HSCT over the course of their treatment. We used the proportion of pPMNs in the blood on day five post-transplant to categorize patients into a high- or a low-pPMN group (> or <10% pPMNs). These groups were then used as a predictor of BSIs. Results A tota...
This prospective cohort study aimed to investigate the impact of maternal oral inflammation on hu... more This prospective cohort study aimed to investigate the impact of maternal oral inflammation on human milk composition including neutrophil counts, activation state (based on cluster of differentiation (CD) markers expression), and fatty acid levels. Fifty mothers were recruited from St. Michael’s hospital, Toronto, and followed up from 2–4 weeks until 4 months postpartum. Oral rinse and human milk samples were collected at both timepoints. Oral polymorphonuclear neutrophils (oPMNs) within the rinses were quantified using flow cytometry and the participants’ oral health state was categorized into three groups (i.e., healthy, moderate, and severe) based on the oPMNs counts. Fatty acids were identified and quantified using a gas chromatography-flame ionization detector (GC-FID). Compared to mothers with a healthy oral health state, mothers with moderate to severe oral inflammation had a statistically significant decrease in the expression of CD64 biomarker, an increase in the expressio...
International Journal of Molecular Sciences, Aug 24, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Background and objectivesPeriodontitis affects the supporting structures of the teeth as a result... more Background and objectivesPeriodontitis affects the supporting structures of the teeth as a result of the interactions between the subgingival biofilm and the host immune system. Periodontal therapy in severe forms of periodontitis often utilizes antimicrobial agents with some potential to improve host defense responses. In the present study, we investigated the in vitro effect of metronidazole (MTZ) at concentrations achievable in the periodontal pocket on PMN activation and PMN mediated killing of Porphyromonas gingivalis.Materials and methodsFlow cytometry based assays were used to measure the impact of MTZ on PMN degranulation, neutrophil extracellular trap (NET) formation and myeloperoxidase (MPO) release and phagocytosis in response to the keystone oral pathogen P. gingivalis. Functional assays for PMN mediated killing of P. gingivalis and reactive oxygen species (ROS) production in PMN were also carried out.ResultsWe demonstrate that PMNs pretreated with MTZ (2 μg/ml or 50 μg/...
All biomaterials, when implanted in vivo, elicit cellular and tissue responses. These responses i... more All biomaterials, when implanted in vivo, elicit cellular and tissue responses. These responses include the inflammatory and wound healing responses, foreign body reactions, and fibrous encapsulation of the implanted materials. Macrophages are myeloid immune cells that are tactically situated throughout the tissues, where they ingest and degrade dead cells and foreign materials in addition to orchestrating inflammatory processes. Macrophages and their fused morphologic variants, the multinucleated giant cells, which include the foreign body giant cells (FBGCs) are the dominant early responders to biomaterial implantation and remain at biomaterial-tissue interfaces for the lifetime of the device. An essential aspect of macrophage function in the body is to mediate degradation of bio-resorbable materials including bone through extracellular degradation and phagocytosis. Biomaterial surface properties play a crucial role in modulating the foreign body reaction in the first couple of weeks following implantation. The foreign body reaction may impact biocompatibility of implantation devices and may considerably impact short-and long-term success in tissue engineering and regenerative medicine, necessitating a clear understanding of the foreign body reaction to different implantation materials. The focus of this review article is on the interactions of macrophages and foreign body giant cells with biomaterial surfaces, and the physical, chemical and morphological characteristics of biomaterial surfaces that play a role in regulating the foreign body response. Events in the foreign body response include protein adsorption, adhesion of monocytes/macrophages, fusion to form FBGCs, and the consequent modification of the biomaterial surface. The effect of physico-chemical cues on macrophages is not well known and there is a complex interplay between biomaterial properties and those that result from interactions with the local environment. By having a better understanding of the role of macrophages in the tissue healing processes, especially in events that follow biomaterial implantation, we can design novel biomaterials-based tissue-engineered constructs that elicit a favorable immune response upon implantation and perform for their intended applications.
The oral cavity hosts over 700 different microbial species that produce a rich reservoir of bioac... more The oral cavity hosts over 700 different microbial species that produce a rich reservoir of bioactive metabolites critical to oral health maintenance. Over the last two decades, new insights into the oral microbiome and its importance in health and disease have emerged mainly due to the discovery of new oral microbial species using next-generation sequencing. This advancement has revolutionized the documentation of unique microbial profiles associated with different niches and health/disease states within the oral cavity and the relation of the oral bacteria to systemic diseases. However, less work has been done to identify and characterize the unique oral microbial metabolites that play critical roles in maintaining equilibrium between the various oral microbial species and their human hosts. This article discusses the most significant microbial metabolites produced by these diverse communities of oral bacteria that can either foster health or contribute to disease. Finally, we she...
David Meiri,1 Christopher B. Marshall,1,2 Melissa A. Greeve,1 Bryan Kim,1 Marc Balan,1,2 Fernando... more David Meiri,1 Christopher B. Marshall,1,2 Melissa A. Greeve,1 Bryan Kim,1 Marc Balan,1,2 Fernando Suarez,1 Chris Bakal,1 Chuanjin Wu,1 Jose LaRose,1 Noah Fine,1,2 Mitsuhiko Ikura,1,2,* and Robert Rottapel1,2,3,4,* 1Ontario Cancer Institute and the Campbell Family Cancer Research Institute, 101 College Street, Room 8-703 Toronto Medical Discovery Tower, University of Toronto, Toronto, ON M5G 1L7, Canada 2Department of Medical Biophysics 3Departments of Medicine and Immunology University of Toronto, 1 King’s College Circle, Toronto, ON M5S 1A8, Canada 4Division of Rheumatology, St. Michael’s Hospital, 30 Bond Street, Toronto, ON M5B 1W8, Canada *Correspondence: [email protected] (M.I.), [email protected] (R.R.) DOI 10.1016/j.molcel.2012.01.027
The presence of periodontal diseases (PDs) often strongly correlates with other severe chronic in... more The presence of periodontal diseases (PDs) often strongly correlates with other severe chronic inflammatory conditions, including cardiovascular disease, diabetes, and arthritis. However, the mechanisms through which these diseases interact are unclear. In PD, tissue and bone destruction in the mouth is driven by elevated recruitment of polymorphonuclear neutrophils (PMNs), which are primed and recruited from the circulation to sites of inflammation. We predicted that systemic effects on PMN mobilization or priming could account for the interaction between PD and other inflammatory conditions. We tested this using a mouse model of ligature-induced PD and found elevated PMN counts specifically in bone marrow, supporting a systemic effect of periodontal tissue inflammation on PMN production. In contrast, mice with induced peritonitis had elevated PMN counts in the blood, peritoneum, and colon. These elevated counts were further significantly increased when acute peritonitis was induce...
Renal ischemia reperfusion injury (IRI) is associated with inflammation, including neutrophil inf... more Renal ischemia reperfusion injury (IRI) is associated with inflammation, including neutrophil infiltration that exacerbates the initial ischemic insult. The molecular pathways involved are poorly characterized and there is currently no treatment. We performed an in silico analysis demonstrating changes in NFκB-mediated gene expression in early renal IRI. We then evaluated NFκB-blockade with a BRD4 inhibitor on neutrophil adhesion to endothelial cells in vitro, and tested BRD4 inhibition in an in vivo IRI model. BRD4 inhibition attenuated neutrophil adhesion to activated endothelial cells. In vivo, IRI led to increased expression of cytokines and adhesion molecules at 6 h post-IRI with sustained up-regulated expression to 48 h post-IRI. These effects were attenuated, in part, with BRD4 inhibition. Absolute neutrophil counts increased significantly in the bone marrow, blood, and kidney 24 h post-IRI. Activated neutrophils increased in the blood and kidney at 6 h post-IRI and remained ...
OBJECTIVES Adverse socioeconomic conditions have been suggested to "get under the skin"... more OBJECTIVES Adverse socioeconomic conditions have been suggested to "get under the skin" through eliciting a stress response that can trigger periodontal inflammation. We aimed to: (1) estimate the extent to which socioeconomic position (SEP) associates with periodontal disease (PD) and pro-inflammatory oral immunity (2) determine the contribution of psychosocial stress and stress hormones to these relationships. METHODS In this cross-sectional study (n=102), participants (20-59 years old) completed financial and perceived stress questionnaires and underwent full-mouth periodontal examinations. SEP was characterized by annual household income and educational attainment. Cortisol, a biological correlate of chronic stress, was assessed in hair samples. Oral immunity was characterized by assessing oral inflammatory load and pro-inflammatory oral neutrophil function. Blockwise Poisson and logistic regression models were applied. RESULTS Compared to lower SEP, individuals in the middle and higher income categories had a significantly lower probability of PD (IRR=0.5, 95%CI 0.3, 0.7 and IRR=0.4, 95%CI 0.2, 0.7) and OIL (IRR=0.6, 95%CI 0.3, 0.8 and IRR=0.5, 95%CI 0.3, 0.7) and were less likely to have a pro-inflammatory oral immune function (OR=0.1, 95%CI 0.0, 0.7 and OR= 0.1, 95%CI 0.0, 0.9). PD and oral immune parameters were significantly associated with financial stress and cortisol. Adjusting for financial stress and cortisol partially attenuated the socioeconomic differences in PD to IRR=0.7, 95%CI 0.5,0.8 and IRR=0.6, 95%CI 0.5,0.7 for the middle and higher income categories, respectively. Similar results were observed for pro-inflammatory immunity (OR=0.2, 95%CI 0.0,1.8 and OR=0.3, 95%CI 0.0, 2.3). CONCLUSION These findings suggest that psychosocial stress may contribute to a pro-inflammatory immunity that is implicated in PD pathobiology, and provide insight into social-to-biological processes in oral health.
Polymorphonuclear neutrophils (PMNs) are the most common leukocytes in the circulation and exhibi... more Polymorphonuclear neutrophils (PMNs) are the most common leukocytes in the circulation and exhibit a wide range of distinct cellular phenomena as part of their microbicidal killing activities, including degranulation, phagocytosis, reactive oxygen species (ROS) production, adhesion, chemotaxis and production of PMN Extracellular Traps (NETs). As a simple in vitro test of PMN functional responses in human blood we have developed a multicolor flow cytometry-based assay of PMN cluster of differentiation (CD) surface marker expression. Short incubations of whole human blood can be performed in the presence of a wide range of agonists or inhibitors, followed by sensitive detection of changes in CD marker expression. This protocol has the advantage that small amounts of human blood are necessary and there are no PMN isolation steps, which can alter PMN activation status.
Polymorphonuclear neutrophils (PMNs) are the most abundant circulating leukocytes, and the first ... more Polymorphonuclear neutrophils (PMNs) are the most abundant circulating leukocytes, and the first cells recruited to sites of tissue inflammation. Using a fixation method to preserve native CD marker expression prior to immunophenotyping, we identified a distinct population of “primed for recruitment” PMNs in healthy mouse and human blood that has high expression of adhesion and activation markers compared with the bulk resting-state PMNs. In response to acute tissue inflammation, primed PMNs (pPMNs) were rapidly depleted from the circulation and recruited to the tissue. One hour after acute peritoneal insult, pPMNs became the dominant PMN population in bone marrow (BM) and blood, returning to baseline levels with resolution of inflammation. PMN priming was induced by the granulopoietic factors granulocyte-macrophage–colony-stimulating factor (GM-CSF) and granulocyte–colony-stimulating factor (G-CSF). High levels of pPMNs were observed in neutropenic mice and in pediatric neutropenic...
Neutrophils, the most numerous leukocytes, play an important role in maintaining oral health thro... more Neutrophils, the most numerous leukocytes, play an important role in maintaining oral health through interactions with oral microbial biofilms. Both neutrophil hyperactivity and the bacterial subversion of neutrophil responses can cause inflammation-mediated tissue damage like that seen in periodontal disease.
Neutrophils play a crucial role in the immune response, leaving the circulation to participate in... more Neutrophils play a crucial role in the immune response, leaving the circulation to participate in an inflammatory response to perceived pathogens. Yet in the oral cavity, they are constantly recruited into the gingival sulcus even in health, producing no apparent clinical inflammation. It has been demonstrated that in this homeostatic state the neutrophils present a "partially active" phenotype, termed para-inflammation. To further investigate this phenotype, we studied the morphology of neutrophils obtained in vivo under transmission electron microscopy (TEM), in health and Chronic Periodontitis (CP), in the blood and the oral cavity. To study and compare the changes induced by the commensal oral bacteria in vitro, blood neutrophils were also incubated separately with S. oralis cultures. Our hypothesis was that the neutrophils in the healthy oral cavity will present a morphology consistent with para-inflammation, in contrast to the naïve phenotype of blood neutrophils, and the fully active, pro-inflammatory oral neutrophils in CP. iii Acknowledgments I would first like to express my deepest thanks and gratitude to my supervisor and mentor Dr. Michael Glogauer, for his incredible support and guidance, and for putting his faith in me. I am extremely lucky to have such knowledgeable, hardworking, and kind person as my guide. Needless to say, without him none of this would have happened. To Drs. Howard Tenenbaum and Bernhard Ganss, whose insightful guidance and comments made all the difference, thank you for steering the ship in the right direction.
Progression of inflammatory osteolytic diseases, including rheumatoid arthritis and periodontitis... more Progression of inflammatory osteolytic diseases, including rheumatoid arthritis and periodontitis, is characterized by increased production of proinflammatory mediators and matrix-degrading enzymes by macrophages and increased osteoclastic activity. Phenotypic changes in macrophages are central to the healing process in virtually all tissues. Using a murine model of periodontitis, we assessed the timing of macrophage phenotypic changes and the impact of proresolving activation during inflammatory osteolysis and healing. Proinflammatory macrophage activation and TNF-α overproduction within 3 wk after induction of periodontitis was associated with progressing bone loss. Proresolving activation within 1 wk of stimulus removal and markers of resolving macrophages (IL-10, TGF-β, and CD206) correlated strongly with bone levels. In vivo macrophage depletion with clodronate liposomes prevented bone resorption but impaired regeneration. Induction of resolving macrophages with rosiglitazone, ...
Neutrophils in circulation experience significant shear forces due to blood flow when they tether... more Neutrophils in circulation experience significant shear forces due to blood flow when they tether to the vascular endothelium. Biochemical and biophysical responses of neutrophils to the physical force of flowing blood modulate their behavior and promote tissue recruitment under pro-inflammatory conditions. Neutrophil mechanotransduction responses occur through mechanisms that are not yet fully understood. In our recent work, we showed that GEF-H1, a RhoA specific guanine nucleotide exchange factor (GEF), is required to maintain neutrophil motility and migration in response to shear stress. GEF-H1 re-localizes to flottilin-rich uropods in neutrophils in response to fluid shear stress and promotes spreading and crawling on activated endothelial cells. GEF-H1 drives cellular contractility through myosin light chain (MLC) phosphorylation downstream of the Rho-ROCK signaling axis. We propose that GEF-H1-dependent cell spreading and crawling in shear stress-dependent neutrophil recruitme...
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