Analysis of in situ proliferative activity in oral gingival epithelium in patients with xerostomia

Association between Sjögren's Syndrome and Periodontitis: Epidemiological, Fundamental and Clinical Data: A Systematic Review

In recent decades, researchers have investigated the bidirectional links between periodontal disease and systemic diseases, and the results have allowed the development of the concept of periodontal medicine. This concept incorporates and analyzes the mutually influential interactions that can occur between periodontitis and systemic diseases such as diabetes mellitus or cardiovascular diseases. Sjögren's syndrome (SS) is a chronic autoimmune disorder that targets the exocrine glands of the body, such as the lacrimal and salivary glands. The amount of saliva produced may gradually decrease with the progression of the disease, which can have an impact on the structures within the oral cavity. Although the reduction in saliva flow produces negative effects in the oral cavity, a direct association between Sjögren's syndrome and periodontal disease has not yet been demonstrated. Available studies on this topic have not identified significant differences in the periodontal status of patients with Sjögren's syndrome and control groups at the clinical and bacteriological levels. On the other hand, other studies on this topic consider that patients with periodontitis have a higher risk of developing Sjögren's syndrome than the general population. Therefore, the results remain inconclusive, highlighting the need for further complementary studies.

Dental Caries and Gingival Evaluation in Children with Congenital Heart Disease

Background

Dental health is one of the most important health burdens of children health. The association between dental health and endocarditis has been already demonstrated, but there is controversy about different frequency of dental caries, periodontitis, and saliva microorganism in comparison to healthy population and children with congenital heart diseases (CHDs). In this study, we evaluated these differences.

Methods

Seventy-six healthy children and 68 CHD patients were enrolled in the present case-control study. Dental decay, periodontitis, oral microorganisms, serum calcium, phosphorus, and frequency of carbohydrate and protein consumption of all participants were evaluated by standards method.

Results

CHD patients experienced more periodontitis, but the difference was not significant (0.12 vs. 0.09, P = 0.2). In healthy children, the mean saliva colony counts of Streptococcus mutans were more significant (50639 ± 3324 vs. 35285 ± 27226, P = 0.03), which was diminished by adjusting the carbohydrate consumption. The mean colony count of Lactobacilli in children with CHD was nonsignificant higher than healthy children (P = 0.3).

Conclusions

Pediatric patients with CHD experience insignificantly higher dental decay, periodontitis, and saliva Lactobacilli colony counts. The frequency of decayed tooth and gingival diseases in healthy children is high, and hence, more dental care attention in our health system is needed for healthy children.

Histological and immunological characteristics of the junctional epithelium

The continuity of epithelial tissue is collapsed by tooth eruption. The junctional epithelium (JE) is attached to the tooth surface by hemidesmosomes, which constitutes the front-line defense against periodontal bacterial infection. JE constitutively expresses intercellular adhesion molecule-1 (ICAM-1), and neutrophils and lymphocytes penetrate into JE via interaction between ICAM-1 and LFA-1 expressed on the surface of these migrating cells. JE also expresses cytokines and chemokines. These functions of JE are maintained even in germ-free condition. Therefore, the constitutive expression of adhesion molecules, cytokines, and chemokines might be used not only for anti-pathogenic defense but also for maintaining the physiological homeostasis of JE. In this review, we have mainly focused on the structural and functional features of JE, and discussed the function of intraepithelial lymphocytes in JE as a front-line anti-microbial defense barrier and regulator of JE hemostasis.

Epithelial TRPV1 signaling accelerates gingival epithelial cell proliferation

Transient receptor potential cation channel subfamily V member 1 (TRPV1), a member of the calcium-permeable thermosensitive transient receptor potential superfamily, is a sensor of thermal and chemical stimuli. TRPV1 is activated by noxious heat (> 43°C), acidic conditions (pH < 6.6), capsaicin, and endovanilloids. This pain receptor was discovered on nociceptive fibers in the peripheral nervous system. TRPV1 was recently found to be expressed by non-neuronal cells, such as epithelial cells. The oral gingival epithelium is exposed to multiple noxious stimuli, including heat and acids derived from endogenous and exogenous substances; however, whether gingival epithelial cells (GECs) express TRPV1 is unknown. We show that both TRPV1 mRNA and protein are expressed by GECs. Capsaicin, a TRPV1 agonist, elevated intracellular Ca(2+) levels in the gingival epithelial cell line, epi 4. Moreover, TRPV1 activation in epi 4 cells accelerated proliferation. These responses to capsaicin were inhibited by a specific TRPV1 antagonist, SB-366791. We also observed GEC proliferation in capsaicin-treated mice in vivo. No effects were observed on GEC apoptosis by epithelial TRPV1 signaling. To examine the molecular mechanisms underlying this proliferative effect, we performed complementary (c)DNA microarray analysis of capsaicin-stimulated epi 4 cells. Compared with control conditions, 227 genes were up-regulated and 232 genes were down-regulated following capsaicin stimulation. Several proliferation-related genes were validated by independent experiments. Among them, fibroblast growth factor-17 and neuregulin 2 were significantly up-regulated in capsaicin-treated epi 4 cells. Our results suggest that functional TRPV1 is expressed by GECs and contributes to the regulation of cell proliferation.

Epigallocatechin-3-gallate modulates antioxidant and DNA repair-related proteins in exocrine glands of a primary Sjogren's syndrome mouse model prior to disease onset

The autoimmune disorder primary Sjogren's syndrome (SS) is associated with xerostomia and xerophthalmia. SS pathogenesis involves both genetic/epigenetic and environmental factors. A major potential contributor is oxidative stress associated with damage to cellular components, including DNA. We reported previously that the green tea polyphenol epigallocatechin-3-gallate (EGCG) normalizes the elevated levels of proliferating cell nuclear antigen (PCNA), a key component of DNA repair, in the NOD mouse model for SS and type 1 diabetes. The current study examined levels of the antioxidant enzymes peroxiredoxin 6 (PRDX6), catalase and superoxide dismutase (SOD), as well as PCNA, in NOD.B10.Sn-H2 mice, a model for primary SS, and determined the effect of EGCG on their expression. PCNA elevation was detected in the submandibular gland and pancreas by 8 weeks of age in water-fed mice, and increased through 14 weeks of age, prior to overt onset of symptoms. This early PCNA elevation was followed by a decline of peroxiredoxin 6 protein. In contrast, EGCG-fed mice exhibited normal levels of PCNA and peroxiredoxin 6, comparable to healthy untreated BALB/c mice. Similar patterns were observed in the pancreas, even though these mice do not develop diabetes. Thus, elevated PCNA is an early biomarker for exocrine glandular dysfunction associated with SS-like autoimmune disease, accompanied subsequently by decreased PRDX6 antioxidant enzyme levels that could further contribute to oxidative stress, and these changes precede inflammatory cell infiltration. Importantly, EGCG consumption normalizes the expression of these biomarkers in this model. These observations could lead to early diagnosis and intervention of autoimmune disorders.

Upregulation of the Expression of Epidermal Growth Factor and Its Receptor in Gingiva Upon Cyclosporin A Treatment

BACKGROUND

To understand the roles of epidermal growth factor (EGF) and EGF receptor (EGF-R) in cyclosporin A (CsA)-induced gingival overgrowth, expression of EGF and EGF-R upon CsA treatment was examined in an oral epidermoid carcinoma cell line of humans (OECM-1) and in edentulous gingiva of rats.

METHODS

In vitro study: after CsA treatment, OECM-1 cells were harvested to evaluate their mRNA and protein expression of EGF and EGF-R with reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot, and immunocytochemistry (ICC). In vivo study: 3 weeks after extraction of all maxillary molars, 20 male Sprague-Dawley rats were assigned to a CsA group (30 mg/kg, fed daily) and a control group. Five rats per group were sacrificed at weeks 1 and 4. Edentulous ridge specimens were obtained for evaluating their mRNAs and protein expression with RT-PCR, real-time RT-PCR, and immunohistochemistry (IHC). In both in vitro and in vivo experiments, the proliferating potential of epithelial cells was examined by the presence of proliferating cell nuclear antigen (PCNA).

RESULTS

In vitro: dose-dependently increased mRNA expression of EGF and EGF-R in OECM-1 cells was noted after CsA treatment. Protein expressions of EGF and EGF-R were higher in OECM-1 with CsA treatment than without CsA. In vivo: higher mRNA and protein expressions of EGF and EGF-R were also observed in the gingival tissues of CsA-treated rats. In both in vitro and in vivo experiments, greater PCNA expression after CsA treatment was demonstrated.

CONCLUSIONS

Higher expression of EGF and EGF-R upon CsA therapy was observed in OECM-1 epithelial cells of humans and in edentulous gingiva of rats. We suggest that CsA could upregulate gene and protein expression of EGF and EGF-R, and the upregulation may play a role in gingival overgrowth.