Profile of host cell responses to exposure to stressed bacteria in planktonic; dislodged, and intact biofilm mode

Abstract

The host defense response to microbial challenge emerging from the root canal system leads to apical periodontitis. The aim of this study was to evaluate the expression of inflammatory cytokines and Nitric Oxide (NO) by macrophages after interaction with Enterococcus faecalis in the: plankton and dislodged biofilm mode; intact biofilm mode stimulated by calcium hydroxide (CH), CH and chlorhexidine (CHX) or Triple Antibiotic Paste (TAP). For this purpose, culture of macrophages from monocytes in human peripheral blood (N=8) were exposed to the different modes of bacteria for 24 hours. Subsequently, the cytokines, such as, Tumor Necrotic Factor- alfa (TNF-α), interleukin (IL)-1β, IL-6, IL-10; and NO were quantified by Luminex xMAP and Greiss reaction, respectively. In addition to the potential therapeutic effects of the intracanal medication, their antimicrobial activity against Enterococcus faecalis biofilm were also tested in vitro by confocal microscopy. The experiments` data were analyzed by the Kruskal-Wallis test with the Dunn post hoc test (α < 0.05). Bacteria in dislodged biofilm mode were shown to be more aggressive to the immune system than bacteria in plankton mode and negative control, inducing greater expression of NO and TNF-α. Relative to bacteria in intact biofilm mode, the weakest antimicrobial activity occurred in Group CH. In Groups CH/CHX and TAP the percentage of dead bacteria was significantly increased to the same extent. Interestingly, the biofilm itself did not induce the release of pro-inflammatory cytokines - except for NO - while the biofilm treated with TAP and CH based pastes enhanced the levels of IL-6 and TNF-α; and IL-1 β, respectively. In contrast, the levels of a potent anti-inflammatory (IL-10) were increased in Group TAP.

Detoxification of LTA by intracanal medication: analysis by macrophages proinflammatory cytokines production

“…Calcium hydroxide was effective in reducing pro-inflammatory cytokines production after 14 days. Similarly, in a recent study, Ca (OH) 2 was effective in reducing the production of IL-1β, IL-6 and IL-10 after 7 days in an in vitro study 20 . In another study, again calcium hydroxide-based intracanal medications were able to reduce the production of TNF-α and IL-1β in an in vitro study 21 .…”

“…The combined intracanal medication of Ca (OH) 2 and CHX was effective in neutralization of the cytotoxic effects of LTA resulted in a significant reduction of TNF-α, IL-6, G-CSF, IP -10 and nitric oxide production being similar to the Ca (OH) 2 + SS group and different of the control group. Similarly, in a recent study, Ca (OH) 2 + CHX was effective in reducing the production of IL-1β, IL-6 and IL-10 after 7 days in an in vitro study 20 . Clinically, the combined effect of this intracanal medication had no significant complementary role in the reduction of endotoxins 14 , however, in that study, sodium hypochlorite and other irrigants were used before intracanal medication.…”