Host defense peptides clavanins A and MO reduce in vitro osteoclastogenesis

Aim: Several systemic diseases, such as periodontitis and apical periodontitis, can cause extensive bone resorption. Host defense peptides may have the potential for the development of novel therapies for the bone resorption process. This study evaluated the potential of host defense peptides clavanins A, MO, and LL-37 in in vitro osteoclastogenesis. Methods: RAW 264.7 cultures were stimulated with recombinant of receptor activator of nuclear factor kappa B ligand in the presence of different tested concentrations of host defense peptides, besides calcium hydroxide and doxycycline. Cellular viability, nitric oxide production, and a number of differentiated osteoclast-like cells were also evaluated. Results: Results showed that none of the substances were cytotoxic, except for 128 µg.mL-1 of doxycycline after 3 days. Host defense peptides, calcium hydroxide, and doxycycline did not interfere in nitric oxide production or downregulated it. An exception was observed in the presence of 2 µg.mL-1 of doxycycline, in which nitric oxide production was up-regulated. All host defense peptides were capable of reducing osteoclast-like cell differentiation. Conclusion: Host defense peptides clavanins A and MO demonstrated to be potential suppressors of osteoclastogenesis in vitro without interfering in cellular viability and nitric oxide production. These promising results need to be further analyzed in in vivo models of bone resorption

Proteomic analysis of human dental pulp in different clinical diagnosis.

OBJECTIVES: The present study aimed to identify proteins obtained from pulp tissue and correlate with each clinical diagnosis (healthy pulp, inflamed pulp, and necrotic pulp). MATERIALS AND METHODS: A total of forty-five molars were used. Three biological replicas were evaluated. Lysis and sonication were used for protein extraction. Protein quantification was assessed by using the Bradford technique, and shotgun proteome analysis was performed by nanoUPLC-MSE using a Synapt G2 mass spectrometer. Mass spectra data were processed using the Waters PLGS software, and protein identification was done using the human Uniprot database appended to the PLGS search engine. RESULTS: A total of 123 different proteins were identified in all evaluated pulp conditions. Among these, 66 proteins were observed for healthy pulp, 66 for inflamed pulp, and 91 for necrotic pulp. Most protein identification was related to immune response, multi-organism process, platelet activation, and stress in inflamed pulp samples compared to healthy pulp. Proteins related to cellular component organization or biogenesis, developmental process, growth, immune response, multi-organism process, response to stimulus, signaling, stress, and transport were identified in cases of apical periodontitis compared to inflamed pulp. CONCLUSIONS: The progression of the disease to inflamed pulp promoted a high abundance of proteins related to the immune system and stress. Comparing the necrotic pulp with inflamed pulp conditions, a high abundance of proteins was noticed related to metabolism, transport, and response between organisms. CLINICAL RELEVANCE: This finding may assist in future studies of new markers, understanding of tissue engineering, and development of future products.

Immune Response Profile against Persistent Endodontic Pathogens Candida albicans and Enterococcus faecalis In Vitro.

INTRODUCTION: Persistent microorganisms such as Candida albicans and Enterococcus faecalis might be directly related to endodontic treatment failure. The host response to these microorganisms impairs the reestablishment of intraradicular and periradicular health. METHODS: The present investigation evaluated the expression of inflammatory mediators produced by RAW 264.7 cells in the presence of heat-killed antigens (HK) C. albicans and E. faecalis. Cultures of RAW cells were stimulated with both antigens in the presence or absence of recombinant interferon (rIFN)-γ. Parameters of cell viability, production of nitric oxide (NO), as well as the synthesis of interleukin (IL)-1α, IL-6, IL-10, IL-12, monocyte chemotactic protein-1, and tumor necrosis factor (TNF)-α were analyzed. RESULTS: Results demonstrated that cell viability was especially reduced in antigens and rIFN-γ-stimulated groups. Groups stimulated with HK C. albicans upregulated IL-10 production. Otherwise, the addition of rIFN-γ to HK C. albicans upregulated TNF-α and NO production. Groups stimulated with HK E. faecalis upregulated TNF-α production. HK E. faecalis and rIFN-γ upregulated TNF-α and NO synthesis. The production of other cytokines remained unchanged by all stimuli. CONCLUSIONS: Knowledge regarding the host mechanism of response to microorganisms that perpetuate endodontic infection and the periradicular lesions can contribute to optimization of endodontic therapy. The mentioned inflammatory mediators and virulence factors involved in endodontic failure might guide lesion progression and also be targets in the development of disinfectant and immunomodulatory agents.

Antimicrobial peptide-based treatment for endodontic infections--biotechnological innovation in endodontics.

The presence/persistence of microorganisms in the pulp and periapical area corresponds to the maintenance of an exacerbated immune response that leads to the start of periradicular bone resorption and its perpetuation. In endodontic treatment, the available intracanal medications do not have all the desirable properties in the context of endodontic infection and apical periodontitis; they need to include not only strong antimicrobial performance but also an immunomodulatory and reparative activity, without host damage. In addition, there are various levels of resistance to root canal medications. Thus, antimicrobial agents that effectively eliminate resistant species in root canals could potentially improve endodontic treatment. In the emergence of new therapies, an increasing number of studies on antimicrobial peptides (AMPs) have been seen over the past few years. AMPs are defense biomolecules produced in response to infection, and they have a wide spectrum of action against many oral microorganisms. There are some studies that correlate peptides and oral infections, including oral peptides, neuropeptides, and bacterial, fish, bovine and synthetic peptides. So far, there are around 120 published studies correlating endodontic microbiota with AMPs but, according to our knowledge, there are no registered patents in the American patent database. There are a considerable number of AMPs that exhibit excellent antimicrobial activity against endodontic microbiota at a small inhibitory concentration and modulate an exacerbated immune response, down-regulating bone resorption. All these reasons indicate the antimicrobial peptide-based endodontic treatment as an emerging and promising option.