Presence of CXCR3-positive cells and IFN-gamma-producing cells in human periapical granulomas

Application of specialized pro-resolving mediators in periodontitis and peri-implantitis: a review

Scaling and root planning is a key element in the mechanical therapy used for the eradication of biofilm, which is the major etiological factor for periodontitis and peri‐implantitis. However, periodontitis is also a host mediated disease, therefore, removal of the biofilm without adjunctive therapy may not achieve the desired clinical outcome due to persistent activation of the innate and adaptive immune cells. Most recently, even the resident cells of the periodontium, including periodontal ligament fibroblasts, have been shown to produce several inflammatory factors in response to bacterial challenge. With increased understanding of the pathophysiology of periodontitis, more research is focusing on opposing excessive inflammation with specialized pro‐resolving mediators (SPMs). This review article covers the major limitations of current standards of care for periodontitis and peri‐implantitis, and it highlights recent advances and prospects of SPMs in the context of tissue reconstruction and regeneration. Here, we focus primarily on the role of SPMs in restoring tissue homeostasis after periodontal infection.

Genetic and Epigenetic Characterization of Pulpal and Periapical Inflammation

Pulpal and periapical diseases affect a large segment of the population. The role of microbial infections and host effector molecules in these diseases is well established. However, the interaction between host genes and environmental factors in disease susceptibility and progression is less well understood. Studies of genetic polymorphisms in disease relevant genes have suggested that individual predisposition may contribute to susceptibility to pulpal and periapical diseases. Other studies have explored the contribution of epigenetic mechanisms to these diseases. Ongoing research expands the spectrum of non-coding RNAs in pulpal disease to include viral microRNAs as well. This review summarizes recent advances in the genetic and epigenetic characterization of pulpal and periapical disease, with special emphasis on recent data that address the pathogenesis of irreversible pulpal pathosis and apical periodontitis. Specifically, proinflammatory and anti-inflammatory gene expression and gene polymorphism, as well as recent data on DNA methylation and microRNAs are reviewed. Improved understanding of these mechanisms may aid in disease prevention as well as in improved treatment outcomes.

Chemokines in Oral Inflammatory Diseases: Apical Periodontitis and Periodontal Disease

The inflammatory oral diseases are characterized by the persistent migration of polymorphonuclear leukocytes, monocytes, lymphocytes, plasma and mast cells, and osteoblasts and osteoclasts. In the last decade, there has been a great interest in the mediators responsible for the selective recruitment and activation of these cell types at inflammatory sites. Of these mediators, the chemokines have received particular attention in recent years. Chemokine messages are decoded by specific receptors that initiate signal transduction events, leading to a multitude of cellular responses, including chemotaxis and activation of inflammatory and bone cells. However, little is known about their role in the pathogenesis of inflammatory oral diseases. The purpose of this review is to summarize the findings regarding the role of chemokines in periapical and periodontal tissue inflammation, and the integration, into experimental models, of the information about the role of chemokines in human diseases.

T lymphocyte activation and cytokine expression in periapical granulomas and radicular cysts

INTRODUCTION

Radicular cysts (RCs) are periapical lesions resulting in jaw bone destruction. The inflammatory dental periapical granuloma (PG) is considered to be the origin of RC formation; however the mechanism of RC development remains unclear.

METHODS

Cell suspension from the surgically extirpated tissue of 27 RCs and 25 PGs was obtained. Bacteriological analysis of the PG tissue samples was performed in order to define two major groups of PG according to the prevailing causative bacterial infection: the streptococcal PG (PG-S, n=10) and the anaerobe PG (PG-A, n=9) group. The inflammatory response of tissue infiltrating lymphocytes was assessed by following T lymphocyte activation (HLA-DR expression) as well as interferon gamma (IFN-gamma) and interleukin 4 (IL-4) production which were evaluated by the flow cytometry.

RESULTS

In comparison to RC both types of PG contained a higher proportion of activated T cells (HLA-DR) and lower proportion of IL-4 producing cells. PG-A tissue contained increased percentage of CD3 cells and increased percentage of T helper 1 (Th1) cells in comparison with PG-S. In RC the IFN-gamma production is higher than in streptococcal PG-S but similar as in PG-A.

DISCUSSION

Tissue infiltration by Th2 cells and IL-4 production is likely to play an etiopathogenic role in RC formation.

Correlation between phenotypic characteristics of mononuclear cells isolated from human periapical lesions and their in vitro production of Th1 and Th2 cytokines

The development and progression of periapical dental lesions, mediated by the specific immune response, are poorly understood. In these processes, an interplay of different proinflammatory and immunoregulatory cytokines is of crucial importance.

OBJECTIVES

To examine the activation of T helper 1 (Th1) and Th2 immune responses in 25 human periapical lesions based on the ex vivo production of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) by mononuclear cells (PL-MNC).

METHODS

The levels of IFN-gamma and IL-4 in culture supernatants of PL-MNC, determined by ELISA, were correlated with concentrations of these cytokines in cultures of control MNC from peripheral blood (PB-MNC), cellular composition of inflammatory cells and phenotypic characteristics of PL-MNC.

RESULTS

We detected high levels of IFN-gamma in all samples, after cell stimulation with phorbol myristate acetate and Ca(2+) ionophore, that were not statistically different from the levels of IFN-gamma in PB-MNC cultures. IL-4 was detected in 76% samples, but its concentrations were much lower than in PB-MNC samples. The levels of IFN-gamma were higher in cultures of PL-MNC isolated from periapical lesions with predominance of T cells (T-type lesions) and correlated positively with the proportion of antigen-presenting cells (macrophages and dendritic cells), CD4(+) T cells and IgG2(+) B cells/plasma cells. The levels of IL-4 correlated negatively with the proportion of macrophages, but positively with the number of mast cells and IgG4(+) cells. IL-18Ralpha, a stable marker of Th1 cells, was detected on a relatively small proportion of CD3(+) T cells and its expression correlated with the levels of IFN-gamma. However, the expression of ST2L, a stable Th2 cell marker, was not detected. The levels of Th1 and Th2 cytokines did not correlate with clinical characteristics of the lesions, defined by the presence of symptoms.

CONCLUSION

Cumulatively, our results suggest the predominance of Th1 immune response in periapical lesions.

Commensal oral bacteria antigens prime human dendritic cells to induce Th1, Th2 or Treg differentiation

In various immunopathologic conditions, bacterial flora induce an immune response which results in inflammatory manifestations, e.g. periapical granuloma. Dendritic cells provide the main orchestration of specific immune responses. The aim of our study was to test the capacity of distinct oral bacterial antigens (prepared from Streptococcus mitis, Propionibacterium acnes, and Bacteroides spp.) to prime human dendritic cells for stimulation of the T-lymphocyte response. To assess the T-lymphocyte response, the expression of CD25, CD69, intracellular interferon gamma (cIFN-gamma), and intracellular interleukin 4 (cIL-4) was determined. Dendritic cells were prepared from leukocyte buffy coat from healthy blood donors. Monocytes were stimulated with IL-4 and GM-CSF and dendritic cells activated with bacterial lysates. Cell suspensions contained up to 90% dendritic cells, which represented 2-12% of the initial number of mononuclear cells. Lymphocyte subsets that developed in lymphocyte cultures after 1 week of stimulation were analyzed by flow cytometry. Dendritic cells, primed with antigens of Bacteroides fragilis have shown significantly higher activation and expression of intercellular IFN-gamma by T lymphocytes compared to negative controls. The dendritic cells primed with antigens of P. acnes had no effect on T-lymphocyte activation or cytokine production; instead they induced differentiation of T lymphocytes into CD25bright cells (regulatory T cells) with a potentially inhibitory effect on immune response. Dendritic cells primed with antigens of S. mitis induced increased expression of cIL-4. We conclude that commensal oral bacteria antigens prepared from B. fragilis, S. mitis, and P. acnes prime human dendritic cells to induce Th1, Th2, and T(reg) differentiation, respectively. This may advance our understanding of immunopathologic manifestations in the oral cavity and offer new possibilities for redirecting immune responses in mucosal vaccination.

Type 1 chemokine receptor expression in Chagas' disease correlates with morbidity in cardiac patients

Chemokines and chemokine receptors (CKRs) control the migration of leukocytes during the inflammatory process and are important immunological markers of type 1 (CCR5 and CXCR3) and type 2 (CCR3 and CCR4) responses. The coexpression of CKRs (CCR2, CCR3, CCR5, CXCR3, and CXCR4) and intracellular cytokines (interleukin-10 [IL-10], IL-4, tumor necrosis factor alpha [TNF-alpha], and gamma interferon [IFN-gamma]) on T CD4+ and CD8+ peripheral cells from individuals with indeterminate (IND) or cardiac (CARD) clinical forms of Chagas' disease after in vitro stimulation with Trypanosoma cruzi antigens, were evaluated in this study. The percentage of T CD4+ and CD8+ cells coexpressing CCR5 and IFN-gamma, CXCR3 and IFN-gamma, and CXCR3 and TNF-alpha were higher in CARD than in IND individuals; on the other hand, the percentage of T CD4+ or CD8+ cells coexpressing CCR3 and IL-10 or coexpressing CCR3 and IL-4 were lower in CARD individuals than in IND individuals. In addition, a significant positive correlation between the expression of CCR5 or CXCR3 and IFN-gamma was observed in CARD individuals contrasting with a significant positive correlation between the expression of CCR3 and IL-4 and of CCR3 and IL-10 in IND patients. These results reinforce the hypothesis that a T. cruzi-exacerbated specific type 1 immune response developed by CARD chagasic patients is associated with the development of heart pathology.

Resolution of furcation bone loss after non-surgical root canal treatment: application of a peptidase-detection kit for treatment of type I endoperiodontal lesion

Here, we report the management of a type I endoperiodontal lesion with furcation bone loss. A 59-year-old female attended our hospital with the chief complaint of mobility of tooth 46 and recurrent gingival swelling around the tooth. She previously received dental treatment from two dentists, but her condition did not improve. The tooth manifested the symptoms of typical periodontitis, such as gingival swelling, tooth mobility, pus discharge from the periodontal pocket and furcation bone loss. The tooth had no caries and the pulp reacted to an electric pulp test. Careful examination of the gingiva revealed traces of dental fistula. X-ray examination via a gutta percha inserted into the fistula revealed that furcation bone loss was associated with the periapical lesion. We diagnosed a type I endoperiodontal lesion, and applied Periocheck, a detection kit for peptidase-producing bacteria, to check for decreases in bacteria in the furcation and root canals. Soon after non-surgical root canal treatment, the condition of tooth 46 improved without periodontal treatment. After confirming a negative score with Periocheck, the root canal was filled. After 3 months, the furcation bone loss was on the way to recovery. These results indicate that proper diagnosis and confirmation of a decrease in root canal bacteria are important for treating endoperiodontal lesions.