Kristin M. Kolltveit

Systemic Diseases Caused by Oral Infection

Recently, it has been recognized that oral infection, especially periodontitis, may affect the course and pathogenesis of a number of systemic diseases, such as cardiovascular disease, bacterial pneumonia, diabetes mellitus, and low birth weight. The purpose of this review is to evaluate the current status of oral infections, especially periodontitis, as a causal factor for systemic diseases. Three mechanisms or pathways linking oral infections to secondary systemic effects have been proposed: (i) metastatic spread of infection from the oral cavity as a result of transient bacteremia, (ii) metastatic injury from the effects of circulating oral microbial toxins, and (iii) metastatic inflammation caused by immunological injury induced by oral microorganisms. Periodontitis as a major oral infection may affect the hosts susceptibility to systemic disease in three ways: by shared risk factors; subgingival biofilms acting as reservoirs of gram-negative bacteria; and the periodontium acting as a reservoir of inflammatory mediators. Proposed evidence and mechanisms of the above odontogenic systemic diseases are given.

Age estimation of adults from dental radiographs

Previous studies have shown that with advancing age the size of the dental pulp cavity is reduced as a result of secondary dentine deposit, so that measurements of this reduction can be used as an indicator of age. The aim of the present study was to find a method which could be used to estimate the chronological age of an adult from measurements of the size of the pulp on full mouth dental radiographs. The material consisted of periapical radiographs from 100 dental patients who had attended the clinics of the Dental Faculty in Oslo. The radiographs of six types of teeth from each jaw were measured: maxillary central and lateral incisors and second premolars, and mandibular lateral incisors, canines and first premolars. To compensate for differences in magnification and angulation on the radiographs, the following ratios were calculated: pulp/root length, pulp/tooth length, tooth/root length and pulp/root width at three different levels. Statistical analyses showed that Pearsons correlation coefficient between age and the different ratios for each type of tooth was significant, except for the ratio between tooth and root length, which was, therefore, excluded from further analysis. Principal component analyses were performed on all ratios, followed by regression analyses with age as dependent variable and the principal components as independent variables. The principal component analyses showed that only the two first of them had significant influence on age, and a good and easily calculated approximation to the first component was found to be the mean of all the ratios. A good approximation to the second principal component was found to be the difference between the mean of two width ratios and the mean of two length ratios, and these approximations of the first and second principal components were chosen as predictors in regression analyses with age as the dependent variable. The coefficient of determination (r2) for the estimation was strongest when the ratios of the six teeth were included (r2 = 0.76) and weakest when measurements from the mandibular canines alone were included (r2 = 0.56). Measurement on dental radiographs may be a non-invasive technique for estimating the age of adults, both living and dead, in forensic work and in archaeological studies, but the method ought to be tested on an independent sample.

Salivary trefoil factor 3 enhances migration of oral keratinocytes

Trefoil factor 3 (TFF3) is a member of the mammalian TFF family. Trefoil factors are secreted onto mucosal surfaces of the entire body and exert different effects according to tissue location. Trefoil factors may enhance mucosal healing by modulating motogenic activity, inhibiting apoptosis, and promoting angiogenesis. Trefoil factor 3 is secreted from the submandibular gland and is present in whole saliva. The aim of this study was to assess the migratory and proliferative effects of TFF3 on primary oral human keratinocytes and oral cancer cell lines. The addition of TFF3 increased the migration of both normal oral keratinocytes and the cancer cell line D12, as evaluated by a two-dimensional scratch assay. By contrast, no increase in proliferation or energy metabolism was observed after stimulation with TFF3. Trefoil factor 3-enhanced migration was found to be driven partly by the extracellular signal-related kinase (Erk1/2) pathway, as shown by addition of the mitogen-activated protein kinase (MAPK) inhibitor PD 98059. Previous functional studies on trefoil peptides have all been based on cells from monolayered epithelium like the intestinal mucosa; this is the first report to show that normal and cancerous keratinocytes from stratified epithelium respond to TFF stimuli. Taken together, salivary TFF3 is likely to contribute to oral wound healing.

Periodontitis in psoriasis patients. A blinded, case-controlled study

Abstract Objective. Destructive periodontitis is one of the most frequent and widespread bacterial infections in humans. Psoriasis is a common condition in the general population. Since both psoriasis and periodontal diseases are characterized by an exaggerated response of the immune system to the epithelial surface microbiota, there may possibly be an association between these two conditions. The aim of the present pilot study was to investigate the prevalence of periodontal disease in psoriasis patients compared to healthy controls. Material and methods. Dental bite-wing X-rays were obtained from 155 psoriasis patients aged 45–60 years, as well as from 155 age- and gender-matched controls. All X-rays were examined by the same investigator for accumulated destructive periodontitis using bone level and loss of teeth as endpoints. Results. A significantly lower radiographic bone level (p < 0.001) and a significantly higher number of missing teeth (p < 0.001) were observed in the psoriasis cases compared to the controls. Conclusion. Our study indicates that psoriasis patients experience more bone loss than age- and gender-matched controls.

Methods of measuring morphological parameters in dental radiographs: Comparison between image analysis and manual measurements

Measurements of age-related changes in dental tissues are often used when estimating the age of an individual. With the new technology now available, the methods of measurement might be standardized and reproducible. The purpose of the present study was to compare the reliability of manual and computer-assisted measurements of morphological parameters in dental radiographs. Manual measurements were made conventionally using a pair of vernier callipers and a stereomicroscope with a measuring eyepiece. An image analysis software program was employed for the computer assisted measurements. Lengths and widths of tooth and pulp were measured both manually and with computer assistance on periapical radiographs from 40 patients, six teeth in each patient. Statistical analyses showed no significant intra- or inter-observer differences for the manual measurements. Statistically significant intra- and inter-observer differences were, however, found between the manual and computer-assisted measurements. The results implied that, despite advanced technology, conventional methods may be better suited for measuring linear morphological parameters in dental tissue.

Trefoil factor family 3 expression in the oral cavity.

This study examined the expression, in oral keratinocytes and in the major and minor salivary glands, of Trefoil factor family 3 (TFF3) peptide. Trefoil factor family 3 messenger RNA (mRNA) and peptide were detected in cultures of normal oral keratinocytes by quantitative real-time polymerase chain reaction (PCR) and western blotting, respectively. Trefoil factor family 3 was found, by immunohistochemical analyses, to be expressed in the basal layers of the oral mucosal epithelium. In salivary glands, immunohistochemical staining showed that TFF3 peptide expression was strongest in the mucous acini of the submandibular and the small salivary glands. Serous cells in the same glands showed weak staining. In the parotid gland, many serous acini showed weak positive staining, while other areas did not. In all glands examined, the intercalated, striated, and collecting ducts were moderately TFF3-positive. Double immunostaining confirmed that mucous (MUC5B positive) cells were moderately or strongly positive for TFF3 and that some serous (MUC7 positive) cells showed restricted TFF3 expression, mostly in a granular pattern. The prevalence of the TFF3 peptide in the salivary secretions of healthy volunteers was detected by western blotting of saliva from minor salivary glands (four of five) and the parotid gland (one of five) and of mixed submandibular/sublingual saliva (five of five). In conclusion, the submandibular and small salivary glands appear to be the major producers of oral TFF3, but duct cells of all glands and keratinocytes of the oral mucosa may also contribute as sources of TFF3 in the oral cavity.

Signal transduction and gene transcription induced by TFF3 in oral keratinocytes

Trefoil factor family 3 (TFF3) is secreted in saliva. The peptide improves the mechanical and chemical resistance of mucins, and it may act as a motility signal for oral keratinocytes during wound healing. This study aimed to identify novel functions of TFF3 in oral keratinocytes. To achieve this, we used phosphoprotein and messenger RNA (mRNA) arrays to compare TFF3-treated and untreated oral keratinocytes. Analysis of the phosphoprotein array indicated that TFF3 signals through the mitogen-activated protein kinases (MAPKs) c-Jun N-terminal kinase (JNK), p38, and extracellular signal-regulated kinase (ERK1/2), and through the phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB) pathway. Microarray analysis of mRNA showed that TFF3 stimulation induced changes in the expression of genes functionally related to cell death/survival, cell growth and proliferation, and cell movement. The reverse transcription-polymerase chain reaction (RT-PCR) results indicated that the transcription of some immediate-early genes (IEGs) was downregulated, whereas the IEGs FBJ osteosarkoma oncogene (FOS) and C-MYC binding protein (MYCBP2) were transiently upregulated by TFF3 stimulation. Together, the results of the arrays indicate that TFF3 is a modifying factor in pathways regulating cell survival, cell growth and proliferation, and cell migration of oral keratinocytes. Trefoil factor family 3 may therefore promote oral wound healing and it should be considered for the treatment of oral ulcerating diseases, or of other diseases.

Structure function analysis of SH2D2A isoforms expressed in T cells reveals a crucial role for the proline rich region encoded by SH2D2A exon 7

BackgroundThe activation induced T cell specific adapter protein (TSAd), encoded by SH2D2A, interacts with and modulates Lck activity. Several transcript variants of TSAd mRNA exist, but their biological significance remains unknown. Here we examined expression of SH2D2A transcripts in activated CD4+ T cells and used the SH2D2A variants as tools to identify functionally important regions of TSAd.ResultsTSAd was found to interact with Lck in human CD4+ T cells ex vivo. Three interaction modes of TSAd with Lck were identified. TSAd aa239–256 conferred binding to the Lck-SH3 domain, whereas one or more of the four tyrosines within aa239–334 encoded by SH2D2A exon 7 was found to confer interaction with the Lck-SH2-domain. Finally the TSAd-SH2 domain was found to interact with Lck. The SH2D2A exon 7 encoding TSAd aa 239–334 was found to harbour information essential not only for TSAd interaction with Lck, but also for TSAd modulation of Lck activity and translocation of TSAd to the nucleus. All five SH2D2A transcripts were found to be expressed in CD3 stimulated CD4+ T cells.ConclusionThese data show that TSAd and Lck may interact through several different domains and that Lck TSAd interaction occurs in CD4+ T cells ex vivo. Alternative splicing of exon 7 encoding aa239–334 results in loss of the majority of protein interaction motives of TSAd and yields truncated TSAd molecules with altered ability to modulate Lck activity. Whether TSAd is regulated through differential alternative splicing of the SH2D2A transcript remains to be determined.

Transcriptional Activation of the SH2D2A Gene Is Dependent on a Cyclic Adenosine 5′-Monophosphate-Responsive Element in the Proximal SH2D2A Promoter

The SH2D2A gene, encoding the T cell-specific adapter protein (TSAd), is rapidly induced in activated T cells. In this study we investigate the regulation of the SH2D2A gene in Jurkat T cells and in primary T cells. Reporter gene assays demonstrated that the proximal 1-kb SH2D2A promoter was constitutively active in Jurkat TAg T cells and, to a lesser extent, in K562 myeloid cells, Reh B cells, and 293T fibroblast cells. The minimal SH2D2A promoter was located between position −236 and −93 bp from the first coding ATG, and transcriptional activity in primary T cells depended on a cAMP response element (CRE) centered around position −117. Nuclear extracts from Jurkat TAg cells and activated primary T cells contained binding activity to this CRE, as observed in an EMSA. Consistent with this observation, we found that a cAMP analog was a very potent inducer of SH2D2A mRNA expression in primary T cells as measured by real-time RT-PCR. Furthermore, activation of SH2D2A expression by CD3 stimulation required cAMP-dependent protein kinase activity. Thus, transcriptional regulation of the SH2D2A gene in activated T cells is critically dependent on a CRE in the proximal promoter region.

Expression of the T‐cell‐specific adapter protein in oral epithelium

The multifunctional T-cell-specific adapter protein (TSAd) was originally described in T cells but is also expressed in epithelial cells from the respiratory tract and in endothelium. In this study, we found expression of TSAd messenger RNA (mRNA) and protein in both human and murine oral mucosal epithelium as well as in human primary oral keratinocyte cell cultures. In TSAd(-/-) mice, the mucosa and skin appeared macroscopically normal, but severe disturbances were observed in the fine structures of the basal membrane and intercellular epithelial spaces upon analysis using transmission electron microscopy. Oral epithelial cells from TSAd(-/-) mice displayed decreased migration compared with cells from wild-type mice, whereas overexpression of TSAd in a human epithelial cell line resulted in impaired proliferation. This study is the first to show that TSAd is expressed in normal oral mucosa, that it is important for the normal ultrastructural morphology of the epithelium and the basal membrane, and that it is involved in the migration and proliferation of oral keratinocytes.