Host response mechanisms in periodontal diseases

Periodontal diseases usually refer to common inflammatory disorders known as gingivitis and periodontitis, which are caused by a pathogenic microbiota in the subgingival biofilm, including Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Tannerella forsythia and Treponema denticola that trigger innate, inflammatory, and adaptive immune responses. These processes result in the destruction of the tissues surrounding and supporting the teeth, and eventually in tissue, bone and finally, tooth loss. The innate immune response constitutes a homeostatic system, which is the first line of defense, and is able to recognize invading microorganisms as non-self, triggering immune responses to eliminate them. In addition to the innate immunity, adaptive immunity cells and characteristic cytokines have been described as important players in the periodontal disease pathogenesis scenario, with a special attention to CD4+ T-cells (T-helper cells). Interestingly, the T cell-mediated adaptive immunity development is highly dependent on innate immunity-associated antigen presenting cells, which after antigen capture undergo into a maturation process and migrate towards the lymph nodes, where they produce distinct patterns of cytokines that will contribute to the subsequent polarization and activation of specific T CD4+ lymphocytes. Skeletal homeostasis depends on a dynamic balance between the activities of the bone-forming osteoblasts (OBLs) and bone-resorbing osteoclasts (OCLs). This balance is tightly controlled by various regulatory systems, such as the endocrine system, and is influenced by the immune system, an osteoimmunological regulation depending on lymphocyte- and macrophage-derived cytokines. All these cytokines and inflammatory mediators are capable of acting alone or in concert, to stimulate periodontal breakdown and collagen destruction via tissue-derived matrix metalloproteinases, a characterization of the progression of periodontitis as a stage that presents a significantly host immune and inflammatory response to the microbial challenge that determine of susceptibility to develop the destructive/progressive periodontitis under the influence of multiple behavioral, environmental and genetic factors

Over-expression of forkhead box P3 and its association with receptor activator of nuclear factor-kappa B ligand, interleukin (IL) -17, IL-10 and transforming growth factor-beta during the progression of chronic periodontitis

8 páginas, 5 figuras, 2 tablas -- PAGS nros. 396-403Aim: T regulatory (Treg) cells have been detected in periodontitis lesions, and forkhead box P3 (Foxp3) expression has been negatively correlated to receptor activator of nuclear factor-κ B ligand (RANKL). The aim of this study was to correlate T-helper type 1 (Th1), Th2, Th17 and Treg transcription factor expressions, in gingival tissues from patients undergoing active periodontal tissue destruction, with bone loss-associated cytokines. Materials and Methods: In 10 chronic periodontitis patients undergoing disease progression, the mRNA expressions of T-bet, GATA-3, Foxp3, RORC2, interleukin (IL)-1β, IL-10, IL-17, RANKL, interferon (IFN)-γ and transforming growth factor (TGF)-β1 were quantified using real-time reverse transcription-polymerase chain reaction. The levels of these markers were compared between active and inactive periodontal lesions. Results: In active periodontal lesions, Foxp3, T-bet, RANKL, IL-17, IL-1β and IFN-γ were significantly over-expressed compared with inactive lesions. The expression of IFN-γ was the highest within the active periodontal lesions, similar to that of TGF-β1 within the inactive ones. There was a positive correlation between RANKL and IL-17. Additionally, RANKL and IL-17 were positively correlated with RORC2, but no correlation was detected with Foxp3. Conclusions: These results lead us to speculate that Foxp3+ cells that do not have a regulatory function might have a role in the pathogenesis of active periodontal lesions by down-regulating TGF-β1 and IL-10 synthesis that lead to the over-expression of Th17-associated cytokines RANKL and IL-17Peer reviewe

Asociación de mayores niveles de Rankl y Linfocitos T CD4+ en periodontitis

Propósito: La periodontitis es una enfermedad infecciosa que involucra una sobrerespuesta inmune del hospedero y se caracteriza por la destrucción de los tejidos de soporte del diente. Durante su desarrollo se establece un denso infiltrado celular mononuclear donde el 70% lo constituyen los linfocitos de tipo T, con la capacidad de secretar una serie de citoquinas que participan en los eventos patogénicos de la enfermedad, regulando la inflamación de los tejidos periodontales y la destrucción del hueso alveolar. El objetivo del presente estudio es determinar si en la periodontitis crónica se observan mayores niveles de RANKL y si estos se encuentran asociados a los linfocitos T CD4+ reclutados en los sitios con enfermedad periodontal. Material y Método: En 20 individuos con periodontitis crónica y en 12 individuos controles voluntarios y periodontalmente sanos se determinaron los niveles de mRNA de RANKL mediante RT-PCR tiempo real, se aislaron células gingivales totales para inmunotipificar y cuantificar los leucocitos infiltrantes gingivales y los linfocitos T CD4+ y CD8+ a través de citometría de flujo, en sobrenadantes de cultivos celulares, sin estimular y estimulados con LPS, PHA, extracto bacteriano de Pg e inter-leuquinas 2 y 15, se detectaron los niveles de RANKL mediante ELISA, y se determinó la expresión de RANKL, de células T CD4+ y se colocalizó inmunoreacción positiva para RANKL en linfocitos CD4+ mediante inmunohistoquímica. Resultados: Los pacientes con periodontitis mostraron mayores niveles de mRNA de RANKL (Ct y ΔCt) evaluado mediante RT-PCR (28,791 ± 3,27 vs. 36,514 ± 2,67 y 7,113 ± 3,00 vs. 15,009 ± 2,80, respectivamente) en comparación a individuos periodontalmente sanos, observándose mediante el método 2-ΔΔCt que la expresión de RANKL se incrementó en 238,3 (29,8-1903,4) veces con relación a los sujetos controles. Los individuos con periodontitis mostraron mayores niveles (%)de linfocitos totales (58,5 ±18,45 vs. 41,5 ± 0,89) y de linfocitos T CD4+ y CD8+ (29,1 ± 17,78 vs. 4,6 ± 0,25 y 13,7 ± 7,23 vs. 3,3 ± 0,15, respectivamente), y en cultivos celulares se observaron mayores niveles de RANKL (pg/ml) espontáneos (18,4 ± 5,79 vs. 8,0 ± 1,34) y estimulados con LPS y PHA (33,8 ± 7,30 vs. 21,0 ± 5,60 y 30,1 ± 7,77 vs. 14,5 ± 3,57, respectivamente), en comparación con los individuos periodontalmente sanos. Mediante inmunohistoquímica se observó una mayor inmunoreacción para RANKL y para CD4 en individuos con periodontitis y una clara colocalización de RANKL en linfocitos T CD4+. Conclusión: Estos datos demuestran que mayores niveles de RANKL se encuentran asociados a la periodontitis y que estos mayores niveles se pueden explicar en parte a la actividad de los linfocitos T CD4+ en el sitio de la infección. Ladeterminación de la asociación entre la periodontitis y la síntesis de RANKL constituye un interesante mecanismo molecular que contribuye a explicar en parte la destrucción tisular asociada y permite proyectar posibles nuevas estrategias terapéuticas, mediante la utilización de inhibidores de la actividad de RANKL, tal como osteoprotegerina (OPG), queayudarían a controlar la pérdida de tejido característica de la enfermedad periodontal. &nbsp

Asociación de mayores niveles de Rankl y Linfocitos T CD4+ en periodontitis

Propósito: infiltrado celular mononuclear donde el 70 lo constituyen los linfocitos de tipo T, con la capacidad de secretar una serie de citoquinas que participan en los eventos patogénicos de la enfermedad, regulando la inflamación de los tejidos periodontales y la destrucción del hueso alveolar. El objetivo del presente estudio es determinar si en la periodontitis crónica se observan mayores niveles de RANKL y si estos se encuentran asociados a los linfocitos T CD4+ reclutados en los sitios con enfermedad periodontal. Material y Método: En 20 individuos con periodontitis crónica y en 12 individuos controles voluntarios y periodontalmente sanos se determinaron los niveles de mRNA de RANKL mediante RT-PCR tiempo real, se aislaron células gingivales totales para inmunotipificar y cuantificar los leucocitos infiltrantes gingivales y los linfocitos T CD4+ y CD8+ a través de citometría de flujo, en sobrenadantes de cultivos celulares, sin estimular y estimulados con LPS, PHA, extracto bacteriano de e inter-leuquinas 2 y 15, se detectaron los niveles de RANKL mediante ELISA, y se determinó la expresión de RANKL, de células T CD4+ y se colocalizó inmunoreacción positiva para RANKL en linfocitos CD4+ mediante inmunohistoquímica

Establishment and Stability of the Murine Oral Microbiome

Commensal microbiomes exert critical functions at barrier sites. In particular, establishment of the commensal microbiome after birth dictates immune functionality and tissue homeostasis at mucosal surfaces. To investigate the establishment and stability of the oral mucosal microbiome in mice, we evaluated oral microbiome communities shortly after birth, through adulthood, and up to 1 y of life in a controlled manner, using sequential oral samples from the same mice over time. We further evaluated transmissibility of oral microbiomes from parents and during cohousing experiments and evaluated susceptibility to oral inflammatory disease in mice harboring distinct microbiomes. Our work reveals basic principles in the establishment and stability of a health-associated oral microbiome after birth and provides insights that may be important for host-microbiome experimentation in animal models.Intramural Program of the National Institute of Dental and Craniofacial Research (NIDCR)/National Institutes of Health (NIH) Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) CONICYT FONDECYT 11180505 1118038

The subgingival microbiome in health and periodontitis and its relationship with community biomass and inflammation

The goals of this study were to better understand the ecology of oral subgingival communities in health and periodontitis and elucidate the relationship between inflammation and the subgingival microbiome. Accordingly, we used 454-pyrosequencing of 16S rRNA gene libraries and quantitative PCR to characterize the subgingival microbiome of 22 subjects with chronic periodontitis. Each subject was sampled at two sites with similar periodontal destruction but differing in the presence of bleeding, a clinical indicator of increased inflammation. Communities in periodontitis were also compared with those from 10 healthy individuals. In periodontitis, presence of bleeding was not associated with different α-diversity or with a distinct microbiome, however, bleeding sites showed higher total bacterial load. In contrast, communities in health and periodontitis largely differed, with higher diversity and biomass in periodontitis. Shifts in community structure from health to periodontitis resembled ecological succession, with emergence of newly dominant taxa in periodontitis without replacement of primary health-associated species. That is, periodontitis communities had higher proportions of Spirochetes, Synergistetes, Firmicutes and Chloroflexi, among other taxa, while the proportions of Actinobacteria, particularly Actinomyces, were higher in health. Total Actinomyces load, however, remained constant from health to periodontitis. Moreover, an association existed between biomass and community structure in periodontitis, with the proportion of specific taxa correlating with bacterial load. Our study provides a global-scale framework for the ecological events in subgingival communities that underline the development of periodontitis. The association, in periodontitis, between inflammation, community biomass and community structure and their role in disease progression warrant further investigation

Levels of interleukin-17 in gingival crevicular fluid and in supernatants of cellular cultures of gingival tissue from patients with chronic periodontitis

Background and Aims: Interleukin-17 (IL-17) is a T-cell-derived cytokine that may play an important role in the initiation or maintenance of the pro-inflammatory response and has recently been found to stimulate osteoclastic resorption. The purpose of the present study was to determine the presence of IL-17 in gingival crevicular fluid (GCF) samples and in the culture supernatants of gingival cells from patients with chronic periodontitis. Method: GCF samples were collected during 30 s from two sites in 16 patients from periodontally affected sites (probing depth >= 5 mm, attachment loss >= 3 mm). The comparison with healthy controls was carried out by collecting GCF samples from eight healthy volunteers. GCF was collected using a paper strip and ELISA was performed to determine the total amount of IL-17. Supernatant cellular cultures of gingival cells were obtained from periodontal biopsies taken from 12 periodontitis patients and from eight healthy control subjects during the surgical removal of wisdom teeth. Spontaneous and phytohaemagglutinin (PHA)-stimulated levels of IL-17 were determined by ELISA. Results: The total amount of cytokine IL-17 was significantly higher in the periodontitis group than the control group (45.9 versus 35.6 pg, p = 0.005). Significantly higher GCF volume and amount of total proteins were obtained from periodontitis patients as compared with control subjects (0.98 versus 0.36 mu l, p = 0.0005; 0.12 versus 0.05 mu g, p = 0.0005, respectively). A higher concentration of IL-17 was detected in culture supernatants from periodontitis patients compared with healthy subjects, either without stimulation (36.28 +/- 8.39 versus 28.81 +/- 1.50 mu g/ml, p = 0.011) or with PHA stimulation (52.12 +/- 14.56 versus 39.00 +/- 4.90 mu g/ml, p = 0.012). Treatment with PHA induced a significant increase in the production of IL-17 in healthy subjects and periodontitis patients (p = 0.001 and 0.003). Conclusions: The total amount of cytokine IL-17 in GCF samples and in the culture supernatants of gingival cells are significantly increased in periodontal disease