Skeletal consequences of RANKL-blocking antibody (IK22-5) injections during growth: mouse strain disparities and synergic effect with zoledronic acid.

High doses of bone resorption inhibitors are currently under evaluation in pediatric oncology. Previous works have evidenced transient arrest in long bone and skull bone growth and tooth eruption blockage when mice were treated with zoledronic acid (ZOL). The question of potential similar effects with a RANKL-blocking antibody (IK22.5) was raised. Sensitivity disparities in these inhibitors between mouse strains and synergic effects of zoledronic acid and a RANKL-blocking antibody were subsidiary questions. In order to answer these questions, newborn C57BL/6J and CD1 mice were injected every two or three days (4 injections in total so 7 or 10 days of treatment length) with high doses of a RANKL-blocking antibody. The consequences on the tibia, craniofacial bones and teeth were analyzed by µCT and histology at the end of the treatment and one, two and three months later. The results obtained showed that RANKL-blocking antibody injections induced a transient arrest of tibia and skull bone growth and an irreversible blockage of tooth eruption in C57BL/6J mice. In CD1 mice, tooth eruption defects were also present but only at much higher doses. Similar mouse strain differences were obtained with zoledronic acid. Finally, a synergic effect of the two inhibitors was evidenced. In conclusion as previously observed for bisphosphonates (ZOL), a RANKL-blocking antibody induced a transient arrest in long bone and skull bone growth and a blockage of tooth eruption with however disparities between mouse strains with regard to this last effect. A synergic effect of both bone resorption inhibitors was also demonstrated.

Assessment of gingival mucosa of infant rats during teething.

AIM: The aim of the present study was to perform a histological analysis of the gingival mucosa in infant rats undergoing the teething process. MATERIALS AND METHODS: Eighteen Wistar rats between 8 and 15 days of life were distributed among three groups: group A--without teething; group B--eruption of incisors; and group C--eruption of incisors and molars. The samples included teeth and periodontal tissue from the region of the incisors and molars of each animal. Fragments were processed for histological analysis and submitted to immunohistochemical analysis. RESULTS: In the 8-day-old rats, mild inflammatory infiltrate predominated with mononuclear cells in the pericoronal follicles of the incisors and molars. At 12 days of age, all animals exhibited moderate inflammation in the pericoronal follicles and epithelium of the incisors and mild inflammatory infiltrate with predominantly mononuclear cells in the molars. At 15 days of age, moderate neutrophilic exudate was found in the pericoronal follicles and epithelium of the incisors and molars. Immunohistochemical analysis revealed positivity for interleukin- 1b in the pericoronal follicles in the pre-eruption phase. CONCLUSION: An inflammatory reaction with progressive intensity occurs during the teething process, the response of which is preceded by the release of interleukin-1b. CLINICAL SIGNIFICANCE: Morphological proof of events that occur during teething that can affect the dynamics of the physiologic process manifesting as clinical symptoms.

[Immunolocalization of receptor activator of NF-kappaB ligand and osteoprotegerin during mouse mandibular first molar eruption].

OBJECTIVE: To investigate the immunolocalization of receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG), and to explore the correlation between their expressions and activity of osteoclast during first mandibular molar eruption. METHODS: Mouse mandibles dissected from postnatal day 1.5 to 14.5 were stained respectively for multinucleated osteoclasts using tartrate-resistant acid phosphatase (TRAP) staining, and RANKL and OPG protein expression was examined by immunohistochemical staining. RESULTS: The two peak values of osteoclast/acreage in the occlusal and basal region were both observed on the P1.5 and P9.5; while the two peak values in the lateral region were on P3.5 and P9.5. During the mouse molar eruption, burst of osteoclastogenesis was associated with high expression of RANKL and low expression of OPG. CONCLUSIONS: RANKL and OPG could have a close relationship with the osteoclast activity and two developmental apexes were observed during the molar eruption. The occlusal movement was relatively stable, meanwhile the temporarily accelerative movement to the basal and lateral regions could occur.

Cytokine levels in gingival crevicular fluid of erupting primary teeth correlated with systemic disturbances accompanying teething.

PURPOSE: The aim of this study was to investigate whether there are increased levels of the inflammatory cytokines IL-1beta, IL-8, and TNFalpha in the gingival crevicular fluid (GCF) of erupting primary teeth. This increase could explain such clinical manifestations as fever, diarrhea, increased crying, and sleeping and eating disturbances that occur at this time. METHODS: Sixteen healthy children aged 5 to 14 months (mean=9.8 months) were examined twice a week over 5 months. Gingival crevicular fluid samples were taken from erupting teeth. As a control, GCF was collected from the same teeth 1 month later. Cytokine production was measured by ELISA. Signs and clinical symptoms were listed. Pearson correlation coefficients were used in the comparisons described below. A paired t test was used to analyze the same variable at different times. RESULTS: Fifty teeth of the 16 children were studied. GCF samples were collected from 21 of these teeth. Statistically significant differences (P<.05) were found with regard to the occurrence of fever, behavioral problems, and coughing during the teething period and the control period. During the control period, 72% of the children did not exhibit any clinical manifestations, whereas during the teething period only 22% of the children did not exhibit any clinical manifestations. The study revealed high levels of inflammatory cytokines during the teething period, with a statistically significant difference in TNFalpha levels (P<.05) between the teething period and the control period. Correlations were found between cytokine levels and some of the clinical symptoms of teething: IL-1beta and TNFalpha were correlated with fever and sleep disturbances; IL-beta and IL-8 were correlated with gastrointestinal disturbances; IL-1beta was correlated with appetite disturbances. CONCLUSIONS: Cytonkines appear in the GCF of erupting prmary teeth. The cytokine levels are correlated to some symptoms of teething.

Different distribution of immunocompetent cells in the dentogingival junction during root formation in rat molars.

The distribution of immunocompetent cells in the dentogingival junction of rat molars during root formation was investigated by immunocytochemistry using antibodies to class II major histocompatibility complex (MHC) molecules (OX6-antibody) and monocyte/macrophage lineage cells (ED1-antibody) as well as by histochemical reaction for periodic acid-Schiff (PAS). Two portions (the junctional epithelium in the mesial gingiva of the first molar, and the interdental gingiva between the first and second molars) were selected for observations. At the eruption stage of the first molar (16-18 days after birth), OX6-positive cells, dendritic or oval in shape, were abundantly distributed in the connective tissue between the oral epithelium and tooth germ. Positive cells with slender cell processes were also found beneath the ameloblast layer. At the commencement stage of the first molar occlusion (24-28 days after birth), numerous OX6-positive cells displaying a dendritic fashion existed preferentially in the mesial gingiva, but were fewer in the interdental gingiva. In contrast, the interdental gingiva showed a denser distribution of ED1-positive cells and PAS-reactive polymorphonuclear leukocytes (PMLs) than the mesial gingiva. At the completion stage of root formation (100-120 days after birth), the OX6-immunopositive cells invaded the deeper position of the mesial gingiva with the downgrowth of the epithelium; they had a considerably higher cell density compared with those in the interdental gingiva where PAS-reactive PMLs persisted. These findings indicated that the immunocompetent cells showed a region-specific distribution and cell density by their roles in immune response.

[Clinical, topographic, and morphological characteristics of pathological processes in the retromolar zone]. / Klinicheskie i topografomorfologicheskie osobennosti patologicheskikh protsessov retromoliarnoi oblasti.

Morphological variants of 20 tissue fragments of mandibular retromolar space were analyzed and the data were used for developing a protocol of treatment of difficult eruption of the mandibular third molar using biocomposite materials.

Age-related changes in the immunoreactivity of the monocyte/macrophage system in rat molar pulp.

Defence reactions of the dental pulp potentially involve a variety of immunocompetent cells, particularly class II major histocompatibility complex (MHC)-expressing cells and macrophages. In order to examine how the immunodefence potential of the pulp changes as a function of age, phenotypic distribution of pulpal cells expressing immunoreactivity to monoclonal antibody ED1 (reactive with nearly all macrophages and dendritic cells) was examined immunohistochemically in the lower first molars of developing (new-born to 10-week-old), adult (14-24-week-old) and aged (1-1.5-yr-old) Wistar rats. During tooth development, increasing numbers of ED1+ cells in the pulp also expressed immunoreactivity to ED2 (reactive with a differentiation-related antigen present on resident macrophages). ED1+ and ED2+ cells were distributed throughout the pulp before the tooth formation was completed. OX6+ (class II MHC-expressing) cells started to increase in number shortly after the eruption of the tooth and the increase continued even after the tooth formation had been completed. In aged rats, the density of the pulpal ED1+ cells was maintained at a relatively high level, whereas a significant decrease in the density of OX6+ cells was observed. These results indicate that the density and composition of pulpal cells expressing macrophage-associated antigens vary with increasing age, which most probably is related to changes in the immunological defence potential of the pulp against infection.

Teething and acute graft vs. host disease: a clinical observation.

A 5-month-old girl, treated with bone marrow transplantation for severe combined immunodeficiency, developed two episodes of severe acute graft vs. host disease (GVHD) while teething. A dramatic improvement in GVHD was noted after the completion of tooth eruption. It is suggested that the release of interleukin-1, associated with the traumatized gingival tissue, is the triggering mediator for the GVHD.

Detecçäo e caracterizaçäo das classes de anticorpos anti-Streptococcus mutans presentes na saliva de crianças em diferentes fases de instalaçäo da dentiçäo decídua / Detection and characterization of salivary antibodies against S. mutans in edentulous and dentate children

Um total de 52 crianças, pertecentes à faixa etária de 3 a 34 meses e em diferentes fases de dentiçäo, foram avaliadas quanto à presença de anticorpos salivares dirigidos contra antígenos protéicos de um extrato de Streptococcus mutans. Crianças edêntulas (G1), com dentes anteriores erupcionados (G2), ou com molares decíduos erupcionados (G3) foram selecionadas para o presente estudo. Extrato da bactéria (S. mutans ATCC 25175) foi obtido, e a detecçäo dos anticorpos salivares foi realizada através da técnica ELISA. Apenas 5 por cento das amostras dos G2 ou G3 apresentaram níveis baixos ou indetectáveis de IgA anti-S. mutans. Nas crianças edêntulas essa porcentagem também foi baixa, em torno de 8 por cento (1/12). Com relaçäo à IgG e IgM, respectivamente 83 por cento (10/12) e 67 por cento (8/12) amostras do G1 apresentou valores baixos ou indetectáveis de anticorpos. Nas amostras do G2, 70 por cento apresentaram títulos baixos de IgM e IgG, e nas amostras do G3, 57 por cento apresentaram valores baixos para IgG e 63 por cento para IgM, respectivamente. A separaçäo eletroforética do extrato revelou que a maioria das amostras apresentaram IgA, IgG e IgM dirigidos contra determinadas proteínas, tais como as de 150 kDa, 74 kDa e 39 kDa. Outras amostras apresentaram anticorpos que reconheceram apenas algumas das bandas reveladas por SDS-PAGE. Apenas 1 amostra do G1, reconheceu a banda de 185 kDa com conjugado anti-IgM e duas amostras do G3 apresentaram IgA anti-antígeno I/II. Nenhuma das amostras apresentou IgG anti-antígeno I/II. É possível que, a exposiçäo freqüente da bactéria seja necessária para haver resposta específica a adesina I/II

Ontogeny of immunity to oral microbiota in humans.

This article reviews the ontogeny of immune systems in the human oral cavity that may influence the colonization, accumulation, or pathogenesis of oral microbiota. The prenatal development of cellular components associated with the secretory immune system reveals that the initial organization of tissue into Peyer's patches can first be detected immunohistologically at 11 weeks gestation. Epithelial cells positive for secretory component and immunocytes positive for IgM can be detected in salivary gland tissue by 19 to 20 weeks and continue to predominate during gestation. After birth, immunocytes containing IgA begin to dominate. Essentially, no IgA can be detected in saliva at birth. However, salivary IgA and IgM often appear soon thereafter, presumably in response to environmental antigenic and mitogenic challenges. Salivary IgA in young infants has molecular characteristics of secretory IgA and becomes the quantitatively predominate Ig in saliva. Both IgA subclasses are present in proportions characteristic of adult pure glandular salivas in many 1- to 2-month-old infants, although the appearance of IgA2 is delayed in some subjects. Many innate, antibody, and cellular immune components are found in maternal colostrum and breast milk. The antibacterial properties of these maternal factors are diverse and can exert multifaceted protective effects on the infant's alimentary tract. The infant apparently can mount mucosal immune responses quite early in life. For example, salivary antibody activity to organisms that originally colonize the gut (e.g., E. coli) or the oral cavity (e.g., S. mitis, S. salivarius) can be detected by 1 to 2 months of age. Most of this antibody activity has characteristics of secretory IgA, although some IgM antibody can also be initially detected. Salivary IgA1 and IgA2 antibody specificities to S. mitis and S. salivarius components increase qualitatively and quantitatively during the first few years of life. Salivary IgA antibody to components of streptococci that require hard surfaces for colonization (e.g., S. sanguis and mutans streptococci) generally appear after tooth eruption. The loss of placentally derived maternal IgG antibody specificities to these microbiota in the circulation is replaced by de novo synthesis, presumably as a result of the teething process. These IgG antibodies can enter the oral cavity in the gingival crevicular fluid and by the process of teething.(ABSTRACT TRUNCATED AT 400 WORDS)