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The effects of probiotic supplementation on systemic health and gastrointestinal diseases have been investigated in numerous studies. The aim of this review is to provide an overview of probiotics and their effects on periodontal health. Probiotics show beneficial effects as adjunctive therapeutics and as stand‐alone agents in the treatment and prevention of gingivitis as well as specific clinical parameters of periodontitis. This review focuses on the clinical and microbiological aspects of probiotics in the context of health, gingivitis, and periodontitis. In addition, a special focus on nisin‐producing probiotics and nisin itself showcase their significant potential for oral and systemic use.

Background: Oral dysbiosis is an imbalance in the oral microbiome and is associated with a variety of oral and systemic diseases, including periodontal disease, caries, and head and neck/oral cancer. Although antibiotics can be used to control this dysbiosis, they can lead to adverse side effects and superinfections. Thus, novel strategies have been proposed to address these shortcomings. One strategy is the use of probiotics as antimicrobial agents, since they are considered safe for humans and the environment. Specifically, the Grampositive Lactococcus lactis, a species present in the oral and gut microbiota, is able to produce nisin, which has been used worldwide for food preservation. Objective: The objective of this study was to test whether a nisin probiotic can promote a healthier oral microbiome in pathogen-spiked oral biofilms. Results: We found that L. lactis can prevent oral biofilm formation and disrupt 24-h and 48h pre-formed biofilms. Finally, we demonstrate that both treatments, a nisin-producing L. lactis probiotic and nisin can decrease the levels of pathogens in the biofilms and return the diversity levels back to control or 'healthy' levels. Conclusion: A nisin-producing probiotic, can be used to treat 'disease-altered' biofilms and promote healthier oral biofilms, which may be useful for improving patient oral health.

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Nanotechnology can produce materials with unique features compared to their bulk counterparts, which can be useful for medical applications (i.e. nanomedicine). Among the therapeutic agents used in nanomedicine, small molecules or biomacromolecules, such as proteins or genetic materials, can be designed for disease diagnostics and treatment. To transport these biomacromolecules to the target cells, nanomedicine requires nanocarriers. Solid lipid nanoparticles (SLNs) are among the promising nanocarriers available, because they can be made from biocompatible materials and present high stability (over one year). In addition, upon the binding genetic material, SLNs form SLNplexes. However, little is yet known about how cells process these SLNplexes-in particular, how internalization and endosome acidification affects the transfection mediated by SLNplexes. Therefore, we aim to investigate how these processes affect SLNplex transfection in HEK293T cells. We find that the SLNplex is mainly internalized by clathrin-mediated endocytosis, which is a fast and reliable pathway to transfection, leading to approximately 60% transfection efficiency. Interestingly, upon acidification (below pH 5.0), the SLN seems to release its DNA content, which can be an essential step for SLNplex transfection. The underlying mechanisms described in this work may help improve SLNplex formulations and transfection efficiency. Moreover, these advances can improve the field of nanomedical research and bring new ways to cure diseases.

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Recebido em 02/05/2016; aceito em 15/06/2016; publicado na web em 16/08/2016 STUDYING THE INTERACTIONS BETWEEN NANOPARTICLES AND BIOLOGICAL SYSTEMS. Although in recent years there has been an increasing amount of literature on nanotechnology and their clinical applications, it is still scarce a deep understanding of the interactions at the molecular levels between nanoparticles and cells. Studies demonstrating the underlying mechanisms of nanoparticles endocytosis, intracellular trafficking, and cellular processing are imperative to understand better how cells interact with those materials and their possible undesired effects, e.g. nanotoxicity. The rising awareness concerning nanoparticles applications and its interactions with the cellular environment is part of the new research field called Nanotoxicology. The cumulative knowledge in nanotoxicology will allow us to foresee toxic effects, establish regulations and limits for nanoparticles applications. In this work, we discuss the theoretical concepts about studying endocytosis and intracellular trafficking of nanoparticles. The nanoparticles-cell interactions are a multi-step process, which can be divided into nanoparticles' internalization, intracellular processing and triggering effects of nanomaterials on eukaryotic cells. Finally, we discuss the main techniques used to study this process: flow cytometry, use of endocytosis inhibitors and confocal microscopy.Keywords: endocytosis; intracellular trafficking; nanoparticles, nanotoxicology; nano-cell interactions. INTRODUÇÃONanotecnologia é um dos ramos mais promissores de tecnologia, sobre o qual se deposita grandes expectativas. 1 Somente em 2015, foram publicados cerca de 9400 artigos relacionados ao termo "Nanotechnology" no banco de dados Science Direct; além disso, diversos produtos têm sido testados e comercializados, por exemplo, protetores solares, cosméticos, produtos biomédicos, biosensores e sistemas para transporte e entrega de fármacos. 2 Entretanto, há uma crescente preocupação com a segurança e possíveis efeitos nocivos de nanomateriais que vêm sendo desenvolvidos, 3 pois dados e regulamentações internacionais referentes à segurança e uso desses materiais ainda são escassos, ainda estão em debate ou em fase de implementação. 4 Uma nova área da ciência destinada ao estudo de efeitos adversos de nanomateriais foi recentemente criada, a Nanotoxicologia. 5 O conhecimento acumulado nessa área tem como objetivo prever efeitos tóxicos e auxiliar nas regulamentações e diretrizes para aplicação da nanotecnologia 6 e uso de produtos a ela relacionados. A Figura 1 mostra o crescimento do número de artigos científicos que contêm o termo "nanotoxicology" e estão no banco de dados do National Center for Biotechnology Information (NCBI), subdivisão do National Institute of Health (NIH/USA).Apesar do número de artigos em nanotoxicologia ser crescente, esta é uma área ainda muito recente (com menos de uma década), e ainda não é possível determinar exatamente quais impactos os sistemas naturais e artificiais co...