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.

Asociación de mayores niveles de RANKL y linfocitos T CD4+ en periodontitis / Increased levels of Rank L and T CD4+ lymphocytes in 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.