Validação biológica de grânulos de vidro bioativas (compostos por biovidro 45S5): estudo in vitro e in vivo / Biological validation of bioactive glass granules (composed of 45S5 bioglass): in vitro and in vivo study

O tecido ósseo, embora tenha a capacidade de regeneração, é limitado em sua eficácia diante de defeitos críticos que impedem a regeneração natural. Dessa forma, materiais como a hidroxiapatita (HA) têm sido considerados promissores na engenharia de tecido ósseo. Contudo, apesar de sua ampla utilização, a hidroxiapatita apresenta desvantagens, como a taxa de reabsorção e remodelação lenta. Em contraste, o biovidro 45S5 se destaca por sua biocompatibilidade, propriedades bioativas e degradabilidade. Este estudo objetivou avaliar o comportamento biológico in vitro e in vivo de grânulos de vidro bioativas de biovidro 45S5 fabricadas pelo método de fusão. Os biovidros foram caracterizados por meio da difração de raios X (DRX), espectroscopia de infravermelho por transformação de Fourier (FTIR), calorimetria diferencial de varredura (DSC) e espectrometria de emissão óptica com plasmas indutivamente acoplados (ICP OES). Em seguida, foi realizado o estudo in vitro, utilizando células osteoblásticas isoladas de fêmures de ratos, que foram submetidas a análise da morfologia celular (MEV), viabilidade celular (MTT), conteúdo de proteína total (PT), atividade de fosfatase alcalina (ALP) e formação de nódulos de mineralização. No estudo in vivo, foram realizados defeitos ósseos críticos de 7 mm na tíbia de coelhos da raça New Zealand, que foram divididos em dois grupos (n=6) de acordo com o material de preenchimento: hidroxiapatita comercial (HA) e biovidro 45S5 (BG45S5). Após 2, 8 e 12 semanas, os animais foram eutanasiados e as peças ósseas foram submetidas as análises histológicas e histomorfométricas. Os dados foram submetidos ao teste de normalidade Shapiro-Wilk (p=0,05) e quando normais realizamos o teste t de student e quando não normais realizamos o teste de Mann-Whitney. Os resultados dos testes físico-químicos mostraram sucesso na produção do novo biomaterial. Nos testes in vitro, observou-se que o grupo BG45S5 não apresentou citotoxicidade e mostrou-se promissor com diferença estatisticamente significante em relação ao grupo hidroxiapatita comercial (p=0.0263). Nos testes de PT, ALP e nódulos de mineralização, os grupos não apresentaram diferença estatística entre eles (p<0,05). Contudo, o grupo BG45S5 mostrou-se promissor em relação aos outros grupos. Na análise histológica, ambos os grupos apresentaram neoformação óssea nos defeitos após 2, 8 e 12 semanas. Na histomorfometria, observou-se que os grupos BG45S5 e HA apresentaram maior área de neoformação óssea em 12 semanas. Houve diferença estatisticamente significante entre os grupos no tempo de 2 semanas, com maior neoformação para o grupo BG45S5. Apesar dos resultados promissores do grupo BG45S5, não houve diferença estatisticamente significativa entre os grupos (p<0,05) nos tempos de 8 e 12 semanas. Em resumo, os resultados evidenciaram o sucesso na produção do biomaterial sintético e o potencial do biomaterial BG45S5 como um material promissor para tratamento de defeitos ósseos críticos. (AU)

Bone tissue, despite its capacity of regeneration, is limited in its effectiveness when faced with critical defects that prevent natural regeneration. Therefore, materials such as hydroxyapatite (HA) have been considered promising in bone tissue engineering. However, despite its wide use, hydroxyapatite has disadvantages, such as slow resorption and remodeling rates. In contrast, 45S5 bioglass stands out for its biocompatibility, bioactive properties and degradability. This study aimed to evaluate the in vitro and in vivo biological behavior of bioactive 45S5 bioglass beads manufactured by the melt quenched method. The bioglasses were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and inductively coupled plasma optical emission spectrometry (ICP OES). Following this, an in vitro study was conducted using osteoblastic cells isolated from rat femurs, which were subjected to analysis of cell morphology (SEM), cell viability (MTT), total protein content (TP), alkaline phosphatase activity (ALP) and mineralization nodule formation. In the in vivo study, critical bone defects of 7 mm were created in the tibia of New Zealand rabbits, which were divided into two groups (n=6) according to the filling material: commercial hydroxyapatite (HA) and bioactive glass 45S5 (BG45S5). After 2, 8, and 12 weeks, the animals were euthanized and the bone pieces were subjected to histological and histomorphometric analyses. Data were subjected to the Shapiro-Wilk normality test (p=0.05), and when normal, we performed the Student's t-test, and when non-normal, we performed the Mann-Whitney test. The results of the physicochemical tests showed success in the production of the new biomaterial. In the in vitro tests, it was observed that the BG45S5 group did not present cytotoxicity and showed promise with a statistically significant difference compared to the commercial hydroxyapatite group (p=0.0263). In the TP, ALP and mineralization nodule tests, the groups showed no statistical difference between them (p<0.05). However, the BG45S5 group showed promise compared to the other groups. In the histological analysis, both groups showed new bone formation in the defects after 2, 8, and 12 weeks. In the histomorphometric analysis, it was observed that the BG45S5 and HA groups presented a larger area of new bone formation at 12 weeks. There was a statistically significant difference between the groups at 2 weeks, with greater new formation for the BG45S5 group. Despite the promising results of the BG45S5 group, there was no statistically significant difference between the groups (p<0.05) at 8 and 12 weeks. In summary, the results evidenced the successful production of the synthetic biomaterial and the potential of the BG45S5 bioglass as a promising material for treating critical bone defect.(AU)

Preliminary Findings on the Salivary Metabolome of Hookah and Cigarette Smokers.

The aim of the study was to evaluate the salivary metabolomic profile of patients who habitually smoke hookah and cigarettes. The groups consisted of 33 regular and exclusive hookah smokers, 26 regular and exclusive cigarette smokers, and 30 nonsmokers. Unstimulated whole saliva was collected for the measurement of salivary metabolites by gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). The MetaboAnalyst software was used for statistical analysis and evaluation of biomarkers. 11 smoking salivary biomarkers were identified using the area under receiving-operator curver criterion and threshold of 0.9. Xylitol and octadecanol were higher in cigarette smokers compared to controls; arabitol and maltose were higher in controls compared to cigarette smokers; octadecanol and tyramine were higher in hookah smokers compared to controls; phenylalanine was higher in controls compared to hookah smokers; and fructose, isocitric acid, glucuronic acid, tryptamine, maltose, tyramine, and 3-hydroxyisolvaleric acid were higher in hookah smokers compared to cigarettes smokers. Conclusions: The evaluation of the salivary metabolome of hookah smokers, showing separation between the groups, especially between the control versus hookah groups and cigarette versus hookah groups, and it seems to demonstrate that the use of hookah tobacco is more damaging to health.

Antifungal effects of Streptococcus mutans extract on Candida strains susceptible and resistant to fluconazole: An in vivo study.

Previous studies showed that the crude extract obtained from Streptococcus mutans inhibited the growth of Candida albicans reference strains. In this study, we evaluated whether the antifungal effects of S. mutans extract can be extended to clinical Candida isolates, including C. albicans and non-abicans strains with different susceptibilities to fluconazole. We verified that S. mutans extract increased the survival of Galleria mellonella larvae infected with C. albicans and C. glabrata and inhibited the fungal cells in hemolymph. These antifungal effects occurred for both fluconazole-susceptible and fluconazole-resistant strains. However, larvae infected by C. krusei were not affected by S. mutans extract. LAY SUMMARY: Streptococcus mutans crude extract shows antifungal effects on clinical Candida strains susceptible and resistant to fluconazole in Galleria mellonella model.

Identificação de possíveis biomarcadores metabolômicos salivares e vias metabólicas alteradas em pacientes com carcinoma de células escamosas bucal / Identification of possible salivary metabolomic biomarkers and altered metabolic pathways in patients with oral squamous cell carcinoma

O carcinoma de células escamosas bucal (CCEB) representa 90% das neoplasias malignas da região intrabucal. O desenvolvimento dessa doença é multifatorial, envolvendo fatores genéticos e ambientais que podem ser, muitas vezes, desconhecidos e que podem apresentar modificação das vias metabólicas. Assim, o objetivo desta pesquisa foi identificar os metabólitos salivares de pacientes com CCEB na busca de vias metabólicas alteradas, assim como possíveis biomarcadores metabólicos. Os metabólitos salivares de 27 pacientes com CCEB foram comparados aos metabólitos de 41 pacientes controles. As amostras de metaboloma salivar foram analisadas por meio de cromatógrafo gasoso acoplado a um espectrômetro de massa (GC-MS). Os resultados indicaram 26 metabólitos específicos para o grupo CCEB e 5 específicos do grupo controle. No diagrama de Venn foram observados 77 metabólitos comuns aos dois grupos. Esta análise foi crucial para a descoberta de três vias metabólicas com diferença estatística entre os grupos: a lançadeira malato-aspartato, a via do metabolismo da beta-alanina e o efeito Warburg. Todas essas vias relacionam-se com a produção de energia celular na carcinogênese, promovendo um ambiente favorável para o alto consumo energético e sobrevivência celular. Ao comparar os metabólitos salivares de pacientes controles e com câncer bucal, 40 metabólitos foram capazes de distinguir os grupos estatisticamente, sendo 20 metabólitos aumentados nos pacientes com carcinoma e 20 aumentados nos pacientes sem a doença. Com a finalidade de identificar os metabólitos como possíveis biomarcadores salivares, a curva ROC foi traçada e um corte de 0,8 no AUC foi construído descobrindo-se 24 metabólitos. Após um novo corte nos metabólitos com AUC de 0,9, metabólitos como ureia, leucina, inosina e metionina puderam ser explorados como candidatos a biomarcadores metabolômicos salivares de pacientes com CCEB já relatados na literatura. Além destes, 6 outros metabólitos apresentaram AUC acima de 0,9 e são relatados pela primeira vez em um estudo de metaboloma salivar de pacientes sul-americanos com câncer bucal, são estes: o ácido málico, maltose, ácido protocatecuico, lactose, ácido-2-cetoadípico e catecol. Essas alterações metabólicas auxiliam na descoberta de biomarcadores salivares de pacientes com câncer bucal e despertam o interesse para que haja outros estudos com maior número de amostras no intuito de validar nossos resultados(AU)

Oral squamous cell carcinoma (CCEB) represents 90% of intraoral malignant neoplasms. The development of this disease is multifactorial, involving genetic and environmental factors that can often be unknown and can present the modification of metabolic pathways. Thus, the objective of this research was to identify the salivary metabolites of patients with CCEB in the search of altered metabolic pathways, as well as possible metabolic biomarkers. The salivary metabolites of 27 patients with CCEB were compared to the metabolites of 41 control patients. The salivary metabolome samples were analyzed using a gas chromatograph coupled to a mass spectrometer (GC-MS). The results indicated 26 specific metabolites for the CCEB group and 5 specifics for the control group. In the Venn diagram 77 other metabolites common to both groups were observed. This analysis was crucial for the discovery of three metabolic pathways with statistical difference between the groups: the malateaspartate shuttle, the beta-alanine metabolism pathway and the Warburg effect. All of these pathways are related to the production of cellular energy in carcinogenesis, promoting a favorable environment for high energy consumption and cell survival. When comparing the salivary metabolites of control patients with oral cancer, 40 metabolites were able to distinguish the groups statistically, with 20 metabolites increased in patients with carcinoma and 20 increased in patients without the disease. In order to identify the metabolites as possible salivary biomarkers, the ROC curve was drawn and a cohort of 0.8 in the AUC was performed by discovering 24 metabolites. After a new cohort of metabolites with AUC of 0.9, metabolites such as urea, leucine, inosine and methionine could be explored as possible salivary metabolomic biomarkers of patients with CCEBs already reported in the literature. In addition to these, 6 other metabolites showed AUC above 0.9 and are reported for the first time in a study of salivary metabolome in South American patients with oral cancer, these are: malic acid, maltose, protocatechuic acid, lactose, 2-ketoadipic and catechol. These metabolic changes help in the discovery of salivary biomarkers of patients with oral cancer and arouse interest for further studies with a larger number of samples in order to validate our results(AU)

Streptococcus mutans Secreted Products Inhibit Candida albicans Induced Oral Candidiasis.

In the oral cavity, Candida species form mixed biofilms with Streptococcus mutans, a pathogenic bacterium that can secrete quorum sensing molecules with antifungal activity. In this study, we extracted and fractioned culture filtrate of S. mutans, seeking antifungal agents capable of inhibiting the biofilms, filamentation, and candidiasis by Candida albicans. Active S. mutans UA159 supernatant filtrate components were extracted via liquid-liquid partition and fractionated on a C-18 silica column to resolve S. mutans fraction 1 (SM-F1) and fraction 2 (SM-F2). We found anti-biofilm activity for both SM-F1 and SM-F2 in a dose dependent manner and fungal growth was reduced by 2.59 and 5.98 log for SM-F1 and SM-F2, respectively. The SM-F1 and SM-F2 fractions were also capable of reducing C. albicans filamentation, however statistically significant differences were only observed for the SM-F2 (p = 0.004). SM-F2 efficacy to inhibit C. albicans was confirmed by its capacity to downregulate filamentation genes CPH1, EFG1, HWP1, and UME6. Using Galleria mellonella as an invertebrate infection model, therapeutic treatment with SM-F2 prolonged larvae survival. Examination of the antifungal capacity was extended to a murine model of oral candidiasis that exhibited a reduction in C. albicans colonization (CFU/mL) in the oral cavity when treated with SM-F1 (2.46 log) and SM-F2 (2.34 log) compared to the control (3.25 log). Although both SM-F1 and SM-F2 fractions decreased candidiasis in mice, only SM-F2 exhibited significant quantitative differences compared to the non-treated group for macroscopic lesions, hyphae invasion, tissue lesions, and inflammatory infiltrate. Taken together, these results indicate that the SM-F2 fraction contains antifungal components, providing a promising resource in the discovery of new inhibitors for oral candidiasis.