In this paper we report on the influence of polysaccharides’ molecular structure on the antibacterial activity and cytotoxicity of composites based on silver nanoparticles (AgNPs) immobilized into carboxymethyl-cellulose (CMC). These composites were green synthesized from the reduction of silver ions into aqueous solutions of the polysaccharide, using CMC with different degree of substitution (DS) and molecular weight (Mw). The composites were characterized by transmission electron microscopy (TEM), as well as infrared (ATR-FTIR), ultraviolet (UV-Vis), Raman, and X-ray photo-electron (XPS) spectroscopic techniques. The antibacterial activity was evaluated with minimum inhibitory concentration against Enterococcus faecalis. The cytotoxicity of composites was assessed against human gingival fibroblast. Experimental evidence suggests that particle size distribution and morphology of AgNPs change according to the quantity of silver precursor added to the reaction, as well as the DS and Mw of CMC used for composites preparation. This is related to the dispersion of silver precursor into aqueous solutions of the polysaccharide and the formation of Ag-O coordination bonds among AgNPs and COO− moieties of CMC. Moreover, these coordination bonds modify the ability of nanoparticles to produce and release Ag+ into aqueous dispersion, adjusting their antibacterial activity and the induction of cytotoxicity into the tested biological environments.
Background
Although several studies have suggested the association between periodontitis, infection by Porphyromona gingivalis and elevated Rheumatoid Arthritis disease activity, its relationship with oral and plasma peptidyl-arginine deiminase (PAD) activity and citrullination of soluble blood proteins remains still poorly known.
Objectives
To evaluate the relationship between periodontal activity, P. gingivalis infection, PAD activity and clínical disease activity of Rheumatoid Arthritis (RA) patients.
Methods
All RA patients included in the present study fulfilled the ACR 2010 criteria, signed an informed consent form and were followed at the rheumatology clinic for one year. Periodontal evaluation and oral and peripheral blood samples were obtained the same day as the rheumatology evaluation by the periodontal screening recording index (PSR). PAD-activity was performed using a colorimetric assay employing as substrate BAEE (Sigma) and as positive control recombinant human PAD4 (Cayman Chem). Citrullination was evaluated by WB of immunoprecipitated saliva and blood fibrinogen, employing polyclonal anti-citrulline antibody (Millipore). Plasma pro-inflammatory cytokines and aCCP levels were evaluated by ELISA. Descriptive statistics were employed to evaluate differences between groups and Spearman correlation was used to associate them with clinical parameters.
Results
A preliminar analysis was done in 48 RA patients whose mean age (41.2 vs. 43 years), BMI (26.8 vs. 27.2) and time since onset of disease (8.5±10.9 vs. 5.44±3.8) were statistically similar between those with high disease activity (DAS28 >3.4) and low disease activity (DAS28 ≤3.4). In contrast to other studies, high disease activity patients were significant associated with a low index of periodontitis (1.57±1.06; p<0.02), while high disease activity patients were associated with severe periodontitis (3.0±1.23). Otherwise, high disease activity patients showed a mean decrease of 1.5 DAS28 units after one year of follow-up, while low disease activity RA patients showed a lower therapeutic response (change of <0.5 DAS28 units). Evaluation of P. gingivalis, PAD activity, fibronectin citrullination are currently performed
Conclusions
Preliminarly, our results suggest that high RA disease activity is negatively associated with severe periodontitis, although the same patients showed a higher therapeutic response after one year of follow up, in comparison to low disease activity RA patients.
Acknowledgements
This work was supported by a grant from SEP/CONACYT CB-2010 (#155392).
Disclosure of Interest
None declared
DOI
10.1136/annrheumdis-2014-eular.3922
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