Unique tailoring of Th17 at the gingival oral mucosal barrier

Our recent work highlights unique requirements for the induction of Th17 cellimmunity at the oral and gingival mucosal barrier. Unlike other barrier sites, such as the skin and gastrointestinal tract, we found that Th17 cells can develop at thegingiva independently of commensal microbiota colonization. Instead, we identifiedthat damage, which occurs physiologically due to mastication, promotes induction of Th17 cells and therefore tones homeostatic immunity at the gingiva

Fibrin is a critical regulator of neutrophil effector function at the oral mucosal barrier

Tissue-specific cues are critical for homeostasis at mucosal barriers. Here, we report that the clotting factor fibrin is a critical regulator of neutrophil function at the oral mucosal barrier. We demonstrate that commensal microbiota trigger extravascular fibrin deposition in the oral mucosa. Fibrin engages neutrophils through the aMb2 integrin receptor and activates effector functions, including the production of reactive oxygen species and neutrophil extracellular trap formation. These immune-protective neutrophil functions become tissue damaging in the context of impaired plasmin-mediated fibrinolysis in mice and humans. Concordantly, genetic polymorphisms in PLG, encoding plasminogen, are associated with common forms of periodontal disease. Thus, fibrin is a critical regulator of neutrophil effector function, and fibrin-neutrophil engagement may be a pathogenic instigator for a prevalent mucosal disease

Foxp3+ T-regulatory cells in Sjögren's syndrome: Correlation with the grade of the autoimmune lesion and certain adverse prognostic factors

Sjögren's syndrome (SS) is a chronic autoimmune exocrinopathy associated with variable lymphocytic infiltration of the affected organs (primarily salivary and lacrimal glands) and broad clinical manifestations, including lymphoma development. To investigate the potential implication of Foxp3+ T-regulatory cells in the regulation of SS inflammatory responses, we studied their incidence in the minor salivary glands (MSGs) and their relationship with histopathological and clinical disease parameters. Similar percentages of infiltrating Foxp3+ cells were observed in the MSG lesions of all SS patients (n = 30) and non-SS sialadenitis controls (n = 7). Foxp3+ cells were not detected in sicca-complaining controls with negative biopsy (n = 6). In SS patients, Foxp3+ cell frequency varied according to lesion severity, with the highest and lowest frequencies obtained in intermediate and mild MSG lesions, respectively. In the peripheral blood of these patients, reverse distribution of Foxp3+ cells was observed. Furthermore, the frequency of Foxp3+ cells in the MSG lesions and peripheral blood was negatively associated (r = -0.6679, P = 0.0065). MSG-infiltrating Foxp3+ cells were found to positively correlate with biopsy focus score (P = 0.05), infiltrating mononuclear cells, dendritic cells, and macrophages (P ≤ 0.024 each), and serum C4 levels (P = 0.0328), whereas lower Foxp3+ cell incidence correlated with adverse predictors for lymphoma development, such as the presence of C4 hypocomplementemia (P = 0.012) and SG enlargement (tendency, P = 0.067). Our findings suggest that the Foxp3+ T-regulatory cell frequency in the MSG lesions of SS patients correlates with inflammation grade and certain risk factors for lymphoma development. Copyright © American Society for Investigative Pathology

Low-grade inflammation in chronic infectious diseases: Paradigm of periodontal infections

Increasing evidence implicates periodontitis, a chronic inflammatory disease of the tooth-supporting structures, as a potential risk factor for increased morbidity or mortality for several systemic conditions including cardiovascular disease (atherosclerosis, heart attack, and stroke), pregnancy complications (spontaneous preterm birth [SPB]), and diabetes mellitus. Cross-sectional, case-control, and cohort studies indicate that periodontitis may confer two- and up to sevenfold increase in the risk for cardiovascular disease and premature birth, respectively. Given the recently acquired knowledge that systemic inflammation may contribute in the pathogenesis of atherosclerosis and may predispose to premature birth, research in the field of periodontics has focused on the potential of this chronic low-grade inflammatory condition to contribute to the generation of a systemic inflammatory phenotype. Consistent with this hypothesis clinical studies demonstrate that periodontitis patients have elevated markers of systemic inflammation, such as C-reactive protein (CRP), interleukin 6 (IL-6), haptoglobin, and fibrinogen. These are higher in periodontal patients with acute myocardial infarction (AMI) than in patients with AMI alone, supporting the notion that periodontal disease is an independent contributor to systemic inflammation. In the case of adverse pregnancy outcomes, studies on fetal cord blood fromSBP babies indicate a strong in utero IgM antibody response specific to several oral periodontal pathogens, which induces an inflammatory response at the fetal-placental unit, leading to prematurity. The importance of periodontal infections to systemic health is further strengthened by pilot intervention trials indicating that periodontal therapy may improve surrogate cardiovascular outcomes, such as endothelial function, and may reduce four- to fivefold the incidence of premature birth. Nevertheless, further research is needed to fully discern the underlying mechanisms by which local chronic infections can have an impact on systemic health, and in this endeavor periodontal disease may serve as an ideal disease model. © 2006 New York Academy of Sciences

Chitinases in the salivary glands and circulation of patients with Sjögren's syndrome: Macrophage harbingers of disease severity

Objective Sjögren's syndrome (SS) is a chronic autoimmune disease of unknown etiology that targets salivary and lacrimal glands and may be accompanied by multiorgan systemic manifestations. To further the understanding of immunopathology associated with SS and identify potential therapeutic targets, we undertook the present study comparing the gene expression profiles of salivary glands with severe inflammation versus those of salivary glands with mild or no disease. Methods Using microarray profiling of salivary gland tissue from patients with SS and control subjects, we identified target genes, which were further characterized in tissue, serum, and cultured cell populations by real-time polymerase chain reaction and protein analysis. Results Among the most highly expressed SS genes were those associated with myeloid cells, including members of the mammalian chitinase family, which had not previously been shown to be associated with exocrinopathies. Both chitinase 3-like protein 1 and chitinase 1, highly conserved chitinase-like glycoproteins (one with enzymatic activity and one lacking enzymatic activity), were evident at the transcriptome level and were detected within inflamed tissue. Chitinases were expressed during monocyte-to-macrophage differentiation and their levels augmented by stimulation with cytokines, including interferon-α (IFNα). Conclusion Because elevated expression of these and other macrophage-derived molecules corresponded with more severe SS, the present observations suggest that macrophages have potential immunopathologic involvement in SS and that the tissue macrophage transcription profile reflects multiple genes induced by IFNα. Copyright © 2011 by the American College of Rheumatology