Increased bone loss and amount of osteoclasts in kinin B1 receptor knockout mice.

AIM: The pathophysiology of periodontal diseases involves aspects of immunity and bone remodelling. Considering the role of the kinin B1 receptor (Bdkrb1) in inflammation and healing, the purpose of this study was to evaluate the contribution of Bdkrb1 to the pathogenesis of periodontitis. MATERIAL AND METHODS: We used a model of ligature-induced experimental periodontitis (LIEP) in mice lacking Bdkrb1 (Bdkrb1(-/-) ) to test the role of this receptor in bone loss and cytokine secretion by lymph nodes cells. Angiotensin-converting enzyme inhibitor (ACEi) was used as a pharmacological strategy to support the genetic model. Also, autonomous effect of Bdkrb1 deletion was evaluated in osteoclasts precursors from bone marrow. RESULTS: Bdkrb1(-/-) mice exhibit increased bone loss and IL-17 secretion in response to LIEP when compared to wild type. LIEP does not modify TNF-α, IFN-γ and IL-10 levels in Bdkrb1(-/-) mice after 21 days. Bone marrow cells from Bdkrb1(-/-) displayed increased differentiation into functional osteoclasts with consistent artificial calcium phosphate degradation. Furthermore, treatment of mice with ACEi prevented bone destruction. CONCLUSION: Bdkrb1 participates in the pathogenesis of LIEP bone loss possibly through mechanisms that involve modulation of the TH 17 response, thereby demonstrating its role in the development of periodontitis.

Role of the second disulfide bridge (Cys(18)-Cys(274)) in stabilizing the inactive AT1 receptor.

Previous research showed that disruption of the Cys(18)-Cys(274) bond in the angiotensin II (AngII) AT1 receptor mutant (C18S), expressed in CHO cells, causes an increase in the basal activity and attenuation of the maximum response to AngII. In addition, this mutant was mostly intracellularly distributed. Our aim was to investigate whether the intracellular presence of the mutant was due to a constitutive internalization or to a defective maturation of the receptor. The first hypothesis was assessed by pretreating the cells with losartan or [Sar¹Leu8]-AngII, specific AT1 receptor antagonists, a maneuver to revert the receptor internalization. The second hypothesis was tested using calnexin, an endoplasmic reticulum marker. We found that treatment with AT1 receptor antagonists causes an increase in the binding ability of the mutant to AngII. Furthermore, whereas the maximum effect is increased, it reduces the enhanced basal levels of IP3. The hypothesis for a lack of maturation of the mutant receptor was ruled out because calnexin was poorly colocalized with the intracellular C18S receptor. Our results suggest that the mutation of the AT1 receptor leads to a conformational structure similar to that of the active mode of the AT1 receptor, favoring its internalization in the absence of the agonist.

ACE activity is modulated by the enzyme α-galactosidase A.

Fabry disease is a multisystem X-linked disorder resulting from α-galactosidase A (α-GalA) gene mutations leading to the accumulation of globotriaosylceramide mainly in endothelium compromising heart, kidney, and brain. In Fabry patients, progressive renal failure is frequently treated with angiotensin I-converting enzyme (ACE) inhibitors. We were interested in the possible interactions between ACE inhibitors therapy and the only causative therapy for Fabry disease, the enzyme replacement therapy (ERT) using recombinant human α-GalA (rhα-GalA). Our results suggest that ACE activity was significantly inhibited in plasma of Fabry patients and the blood pressure level decreased just after ERT (at the end of the rhα-GalA infusion). Interestingly, 2 weeks later, ACE activity was significantly upregulated and the plasma levels of angiotensin II increased in the patients treated with rhα-GalA following the elevations of ACE activity. The same inhibitory effect on ACE activity was also observed in rats after rhα-GalA infusion. Furthermore, ACE activity in CHO cells transfected with the human ACE was inhibited dose and time-dependently by rhα-GalA. In vitro, the incubation of plasma from healthy volunteers with rhα-GalA significantly reduced ACE activity. Finally, rhα-GalA also inhibited ACE activity and released galactose residues from purified rabbit lung ACE dose-dependently. In summary, our results suggest that rhα-GalA interacts with ACE and inhibits its activity, possibly by removing the galactose residues from the enzyme. This modulation might have profound impact on the clinical outcome of Fabry patients treated with rhα-GalA.

Escovas interdentais: aspectos morfológicos de interesse clínico / Interdental brushes: some morphological aspects of clinical interest

Investigou-se a morfologia de 26 diferentes tipos de escova interdental por meio de microscopia óptica e microscopia eletrônica de varredura, além de microanálise quantitativa por raios X. As escovas apresentaram comprimento, diâmetro e firmeza das cerdas variáveis e ponta das cerdas näo polidas, em sua maioria. A microanálise quantitativa por raio X, os fios centrais das escovas continham Fe, Ni e Cr. Das 26 escovas, 13 tinham fios encapados com materiais constituídos de acrílico, Ti ou Si. Essa capa apresentou-se rompida ou dilacerada em várias amostras. Nas escovas de fio sem capa, a ponta do fio central era àspera e com contornos agudos, representando risco para o tecido gengival