Chronic Apical Periodontitis Lesions Research Articles

Aging as a Risk Factor on the Immunoexpression of Pro-Inflammatory IL-1β, IL-6 and TNF-α Cytokines in Chronic Apical Periodontitis Lesions

Simple SummaryApical periodontitis often manifests as a chronic and asymptomatic disease. The formation of chronic apical periodontitis lesion (CAPL) occurs due an imbalance between microorganisms in a root canal system and a host’s immune response. The pro-inflammatory characteristic of periapical granulomas has been established; increased IL-1β, IL-6 and TNF-α has been documented. In humans over 65 years of age, the immune system becomes more fragile, including a persistent inflammatory response, making them more susceptible to reactivation of latent viruses, bacterial and viral pathogens, autoimmune diseases, opportunistic infections and neoplasms. The question of this study is as follows: in aging adults, do chronic apical periodontitis lesions as biomarkers have a risk effect on the immunoexpression of pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) compared to adults? The results demonstrated that the pro-inflammatory cytokines IL-1β, IL-6 and TNFα showed higher expression in the CAPL of the elderly than in the adult control group, thus suggesting that aging could be considered a modifier of periradicular disease. However, although aging is not the main cause for the development of CAPL, it seems to be able to influence its evolution. However, further elaborate research studies/analyses to elucidate the reasons and consequences of inflammation in the elderly are recommended.Persistent inflammatory responses in the elderly may act as modifiers on the progression and repair of chronic apical periodontitis lesions (CAPLs). While the involvement of IL-1β, IL-6 and TNF-α in inflammatory responses and, particularly, in CAPL has been documented, their expression in elderly patients needs to be further characterized. Therefore, the purpose of this study was to evaluate and compare the expressions of pro-inflammatory cytokines in CAPL from elderly individuals with young/middle-aged individuals. Thirty CAPL (15 cysts and 15 granulomas) from elderly patients (>60 years) and 30 CAPL (15 cysts and 15 granuloma) from young/middle-aged individuals (20–56 years) were selected. Immunohistochemical reactions were performed against IL-1β, IL-6 and TNF-α. The slides were subdivided into five high-magnification fields and analyzed. The number of positive stains was evaluated for each antibody. There was no significant difference between the cytokines when the cysts and granuloma were compared in the two groups. In the young/middle-aged, only IL-1β showed a difference and was significantly higher in granulomas (p = 0.019). CAPL pro-inflammatory cytokine levels in the elderly were significantly higher than in young/middle-aged individuals (p < 0.05). The pro-inflammatory cytokines IL-1β, IL-6 and TNF-α were significantly higher in CAPL in the elderly compared with the young/middle-aged group. Further elaborate research studies/analyses to elucidate the reasons for and consequences of inflammation in the elderly are recommended.

Single-Cell Sequencing Unveils the Heterogeneity of Nonimmune Cells in Chronic Apical Periodontitis

Chronic apical periodontitis (CAP) is a unique dynamic interaction between microbial invasions and host defense mechanisms, resulting in bone absorption, infiltration of immune cells and sporadic periapical granuloma. In this study, we constituted a single-cell atlas for 26,737 high-quality cells from hyperplastic periapical tissue using single-cell RNA sequencing. Identifying cell types and signatures at the single-cell level might generate novel insights into the clinical pathogenesis of CAP. A histological analysis to verify the gene signatures of nonimmune cells was combined with immunohistochemistry staining. We then discovered the diversity and heterogeneity of nonimmune cells in regional CAP lesions. The temporal profiling of genomic alterations from common CAP to typical periapical granuloma provided predictions for key transcription factors and biological processes. Our study also inferred that the marked shift of inflammatory cytokines, chemokines, proteases and growth factors enables the initiation of polymorphic cell differentiation, lymphangiogenesis and angiogenesis during CAP.

Expression of Inflammatory Markers RANK, MMP-9 and PTHrP in Chronic Apical Periodontitis from People Living with HIV Undergoing Antiretroviral Therapy.

To compare the expression of the receptor activator of nuclear factor-kappa B (RANK), matrix metalloproteinase 9 (MMP-9) and parathyroid hormone-related protein (PTHrP) in primary chronic apical periodontitis lesions (CAPLs) between people living with HIV (PLWHIV) undergoing antiretroviral therapy (ART) and HIV- individuals, 32 CAPLs (16 lesions from each group) were submitted to histopathological and immunohistochemical analyses and compared between groups. The majority of the PLWHIV group had undetectable plasma viral loads (n = 13; 81.3%). The means of TCD4+ lymphocytes, exposure to HIV-1 and the time of the use of ART were 542.1 cells/mm3 (SD = 256.4), 6.3 years (SD = 2.9) and 5.0 years (SD = 2.5), respectively. Of all variables studied, only histopathological diagnosis showed a significant difference between groups (LWHIV: granuloma n = 11 (68.0%); cyst n = 5 (31.2%); HIV-: granuloma n = 15 (93.8%); cyst n = 1 (6.2%); p = 0.015). When comparing the expressions of the three inflammatory markers between the groups, no significant differences were seen. There was no difference in the expression of RANK, PTHrP and MMP-9 in primary chronic apical periodontitis lesions between PLWHIV under ART and HIV- individuals.

Immunoexpression of bone resorption biomarkers in apical periodontitis in diabetics and normoglycaemics.

To compare the immunoexpression of RANK, MMP-9 and PTHrP in apical periodontitis lesions of diabetic and normoglycaemic individuals. Primary chronic apical periodontitis lesions associated with teeth indicated for extraction in 13 type 2 diabetic individuals and 13 normoglycaemic individuals who were screened for the glycaemic index and glycated haemoglobin (HbA1c) were analysed. Individuals with other systemic diseases and users of anti-inflammatories and/or antibiotics in the previous 3months were excluded. Silanized slides with paraffin sections were used for immunohistochemical reactions and stained with haematoxylin and eosin for histopathological classification. The images were analysed with an optical microscope, and the slides were subdivided into five large fields assigning scores (0-2), according to the number of positive markings for each antibody. Fisher's exact test evaluated the parameters: gender, type of lesion, location and position in the arch. Nonparametric Mann-Whitney test was used for age, HbA1c values and comparison of marker expression. The chi-squared test was used to associate the expression of the markers. And the Spearman's coefficient correlated the markers with the size of the periapical lesion. The samples consisted of 69% periapical granulomas and 31% periapical cysts in each group. RANK expression was considered weak/moderate and strong in, respectively, 62% and 38% of the cases in both groups. MMP-9 expression was weak/moderate and strong in, respectively, 38% and 62% of the cases from the diabetic group, in comparison with 38% and 38% in the normoglycaemics (24% cases from this group were negative). In contrast, PTHrP expression was negative, weak/moderate and strong in, respectively, 46%, 46% and 8% of the cases from the diabetic group, in comparison with 38% negative and 62% weak/moderate in normoglycaemics. Quantitative analysis revealed that there were no significant differences in the immunoexpression of RANK (P=0.26), MMP-9 (P=0.17) and PTHrP (P=0.43) between the groups. There was no significant correlation between the expression of bone resorption markers and the macroscopic size of the periapical lesions (P>0.05). The bone resorption mediators analysed had similar immunoexpression in the periapical lesions of diabetic and normoglycaemic individuals.

Role of interleukin-33 in the clinical pathogenesis of chronic apical periodontitis.

ObjectiveThis study investigated interleukin (IL)-33 expression in chronic apical periodontitis (CAP) lesions and possible relationships with receptor activator of nuclear factor κ-Β ligand (RANKL) and osteoprotegerin (OPG).MethodsInflammatory cell infiltration in CAP lesions and samples of healthy periapical tissue (n = 30 each) was evaluated by hematoxylin and eosin staining. IL-33, RANKL, and OPG expression levels were assessed by immunohistochemistry and real-time PCR. In CAP lesions alone, relationships between mRNA level of IL-33 and mRNA levels of both RANKL and OPG were analyzed by Spearman rank correlation.ResultsHistological analysis revealed a large number of inflammatory cells in CAP lesions, and immunohistochemistry revealed IL-33-positive cells. There were more IL-33- and RANKL-positive cells in CAP lesions than in healthy periapical tissue, whereas there were fewer OPG-positive cells in CAP lesions than in healthy periapical tissue. In CAP lesions alone, IL-33 mRNA level was negatively correlated with mRNA level of RANKL and positively correlated with mRNA level of OPG.ConclusionsIL-33 is highly expressed in CAP lesions, where it is negatively correlated with RANKL and positively correlated with OPG expression. IL-33 may protect against bone resorption via RANKL suppression and OPG induction, and constitutes a potential target for CAP treatment.

Cellular Profile and Expression of Immunologic Markers in Chronic Apical Periodontitis from HIV-infected Patients Undergoing Highly Active Antiretroviral Therapy

IntroductionThis study tested the hypothesis that the inflammatory cell profile (CD3-, CD4-, CD8-, CD20-, and CD68-positive cells) and the expression of immunologic markers (tumor necrosis factor α, interferon-γ, interleukin-6, and interleukin-18) in chronic apical periodontitis are the same between non–HIV-infected patients and HIV-infected patients undergoing highly active antiretroviral therapy (HAART). MethodsThirty-four surgically excised chronic apical periodontitis lesions were sampled from 34 patients (17 HIV-infected and 17 non–HIV-infected). The lesions were extracted from teeth with no previous endodontic treatment. All HIV-infected patients were undergoing HAART. The specimens were submitted to histopathologic and immunohistochemical analyses by using an optical microscope. Immunoexpression was graded into 2 levels, focal to weak and moderate to strong. The χ2, Fisher exact, and Mann-Whitney tests were used to analyze all significant differences between groups. ResultsPeriapical cysts represented 70.6% and 52.9% of the lesions in the HIV-infected and non–HIV-infected groups, respectively; however, no statistically significant difference was observed (P = .481). There were no statistically significant differences between groups for the inflammatory cell profile and for any of the immunologic markers (P > .05). ConclusionsThere are no statistically significant differences of the cellular profile and expression of immunologic markers in chronic apical periodontitis between non–HIV-infected patients and HIV-infected patients undergoing HAART.

Lipids and lipoproteins and inflammatory markers in patients with chronic apical periodontitis.

BackgroundSince chronic apical periodontitis (CAP) appears to be a risk factor for coronary heart disease, the aim of the study was to determine the relationship between the size of CAP lesion and inflammatory markers (hsCRP, IL-6, TNF-α), as well as lipids and lipoproteins (LpPLA2, apoAI, apoB level) in blood serum of patients with CAP.MethodsThe patients studied (n = 43) were divided into groups: patients under 50 and over 50 years of age, and a separate subgroup of the oldest age with the largest size of CAP lesions. Apolipoprotein AI (apoAI) above 150 mg/dL and below 150 mg/dL was used as an important criterion for the division of patients into groups. The CAP lesion size was measured using the Kodak digital imaging system software. The control group consisted of clinically healthy volunteers (n = 20) without CAP. Lipids were measured on a Siemens analyzer (Germany), apoAI, apoB, hsCRP levels were determined by immunonephelometric method, using the Health Care Diagnostic Product (Siemens GmbH, Germany), and IL-6, TNF-α and LpPLAG7 assay kits (ELISA, R&D Systems) were used.ResultsThe findings suggested that in patients with CAP and their age increase, the CAP lesion size, the concentration of inflammatory markers and LpPLA2 mass increased. Correlations between the CAP lesion size and LpPLA2 mass and between the CAP lesion size and TG level in patients with apoAI 150 ≤ mg/dL showed increase TG in atherogenic apoB-containing triglyceride-rich lipoprotein and TC in cholesterol-rich lipoprotein. The patients with a low apoAI and high LpPLA2 level can have a higher risk of odontogenic disease and progression of atherosclerosis and coronary heart disease.ConclusionWe have found a positive correlation between apoAI level and the CAP lesion size and a negative correlation between LpPLA2 level and the CAP lesion size. The results suggest that apoAI and LpPLA2 in HDL particles have antiinflammatory action and together can limit the CAP lesion size in patient with a higher apoAI level. The literature data on the distribution of lipoprotein particles in subjects are still insufficient, so this problem requires further studies.

The association of chronic apical periodontitis and endodontic therapy with atherosclerosis

ObjectivesChronic apical periodontitis (CAP) appears to be a risk factor for coronary heart disease. The aims of the study were to estimate the significance of AP for the atherosclerotic burden and to examine the potential effect of endodontic treatment.Materials and methodsThe whole-body computed tomography (CT) examinations of 531 patients with a mean age of 50 ± 15.7 years were evaluated retrospectively. The atherosclerotic burden of the abdominal aorta was quantified using a calcium scoring method. The parameters of periodontitis were measured using the CT scan.ResultsThe patients had a total of 11,191 teeth. The volume of the aortic atherosclerotic burden for patients with at least one CAP lesion was 0.32 ± 0.92 ml, higher than for patients with no CAP (0.17 ± 0.51 ml; p < 0.05). The atherosclerotic burden increased with age and number of CAP lesions without root canal treatment, but not with number of CAP lesions with endodontic treatments (p < 0.05 each). In logistic regression models, age (Wald 90.8), CAP without endodontic treatment (Wald 39.9), male gender (Wald 9.8), and caries per tooth (Wald 9.0) correlated positively and the number of fillings (Wald 11) correlated negatively with the atherosclerotic burden (p < 0.05 each). Apical radiolucencies in teeth with endodontic treatment were irrelevant with respect to atherosclerosis.ConclusionsCAP correlated positively with the aortic atherosclerotic burden. In regression models, CAP without endodontic treatment was found to be an important factor, not however apical radiolucencies in teeth with endodontic treatment.Clinical relevanceFurther research is needed to clarify the possible clinical significance of these associations.

Bacteria in the apical root canal of teeth with primary apical periodontitis

Bacteria settled in the apical root canal are in a privileged position to inflict damage to the periradicular tissues. Therefore, the species identified in this region can be of special relevance for the pathogenesis of apical periodontitis. This study investigated the occurrence and levels of several bacterial taxa in the apical root canal of teeth with apical periodontitis. DNA extracts from samples taken from the apical part of the root canal of extracted teeth evincing chronic apical periodontitis lesions served as templates for analysis of the presence and levels of 28 bacterial species/phylotypes using a 16S ribosomal RNA gene-based reverse-capture checkerboard hybridization assay. Bacterial DNA was detected in 19 out of 20 samples. Detected taxa included Pseudoramibacter alactolyticus (32%), Bacteroidetes clone X083 (26%), Streptococcus species (21%), Olsenella uli (10.5%), Synergistes clone BA121 (10.5%), Fusobacterium nucleatum (10.5%), Porphyromonas endodontalis (10.5%), Dialister clone BS016 (5%), Filifactor alocis (5%), Parvimonas micra (5%), and Treponema denticola (5%). Of these, only Bacteroidetes clone X083 and Synergistes clone BA121 were found at levels above 10(5). Occurrence of these bacterial taxa in the apical part of infected root canals indicates their potential pathogenetic role in the etiology of apical periodontitis.

Natural killer cells and alterations in collagen density: signs of periradicular herpesvirus infection?

This study evaluated the presence and density of natural killer (NK) cells as well as collagen density in chronic apical periodontitis lesions and tried to find any correlations with concomitant herpesvirus infection or histopathological status of the lesion. Surgical specimens of chronic apical periodontitis lesions were surveyed for the presence and density of NK cells by immunohistochemical analysis. Collagen density in these lesions was quantified by means of histochemistry. All specimens were positive for the presence of CD57-positive cells. Topographically, CD57-positive cells were found singly or forming clusters in the granulomatous tissue, as well as subjacent and within the cystic epithelium. No significant differences in the density of CD57-positive cells were found between nonepithelialized and epithelialized lesions or between herpesvirus-positive and herpesvirus-negative lesions. Significant differences were found in volumetric density of collagen when comparing nonepithelialized and epithelialized lesions, with the latter demonstrating higher values. When no distinction of lesion type was made, there was no significant difference in collagen density between herpesvirus-positive and herpesvirus-negative lesions. When comparing the collagen density in herpesvirus-positive and herpesvirus-negative specimens from the same lesion type, a significant difference was found in nonepithelialized lesions, with herpesvirus-positive lesions showing lower values. The presence of CD57-positive cells in all chronic apical periodontitis specimens may indicate that activated NK cells play a role in the pathogenesis of this disease, possibly by participating in innate immunity events involved in the control of virus infection. Collagen density may vary in function of the type of lesion and presence of herpesvirus infection.

On the use of denaturing gradient gel electrophoresis approach for bacterial identification in endodontic infections

Bacteria in infected root canals of teeth evincing chronic apical periodontitis lesions were identified by a polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) approach. DNA was extracted from root canal samples, and part of the 16S rRNA gene of all bacteria was amplified by PCR and separated by DGGE, generating banding patterns representative of the community structure. Twenty visible bands were cut out of the gel, re-amplified, and sequenced to provide identification. Sequencing analysis revealed the presence of both cultivable and as-yet-uncultivated species in the samples analyzed, including representatives of the genera Fusobacterium, Bacteroides, Dialister, Synergistes, Prevotella, Eubacterium and Peptostreptococcus. Unambiguous identification was not always possible and the method's limitations are discussed. In general, the findings showed that PCR-DGGE can be useful for the identification of both cultivable and as-yet-uncultivated bacteria in endodontic infections.