In vitro effects of ambroxol on Cryptococcus adherence, planktonic cells, and biofilms

Broaden properties of ambroxol hydrochloride as an antibiofilm compound

Biofilm-associated microorganisms can cause many infections and are an important cause of resistance to several antimicrobials. The antibiotic crisis has led to a pressing need for new therapeutic tools. Ambroxol is frequently used as a mucolytic agent in respiratory diseases with increased mucus production. In addition, a wide range of properties has been described, including the effect on biofilms. In this work, we evaluate the anti-biofilm effect of ambroxol on four strains with clinical relevance: Proteus mirabilis, Escherichia coli, Staphylococcus aureus, and Acinetobacter baumannii. In vitro, biofilm formation was assessed using the crystal violet quantification technique in microplate and glass coverslip. The inhibition of biofilm formation was evaluated by adding ambroxol at the initial time. Ambroxol hydrochloride was evaluated over the preformed biofilm and live/dead bacteria were quantified. The effect of ambroxol in the ethidium bromide efflux assay and the relative expression of the five major P. mirabilis efflux pump family genes were analyzed. Ambroxol inhibited biofilm formation in all the bacteria tested. Moreover, ambroxol significantly reduces both biofilm biomass and viable bacteria. Ambroxol was able to affect P. mirabilis efflux pumps depending on the concentration used and induced the overexpression of several efflux pump genes. In summary, ambroxol kills planktonic cells, reduce biofilm biomass as it increases cell death, and affect the expression of efflux pumps. Furthermore, it presents a viable alternative for the treatment of biofilm infection alone or in combination with antibiotic therapy.

Biological and antimicrobial properties of the association Ambroxol and a water-soluble viscous liquid as a vehicle for a tricalcium silicate-based sealer

This study aimed to investigate the antimicrobial and biological properties of Ambroxol associated with glycerin (GLI), propylene glycol (PG), and polyethylene glycol (PEG) as a possible vehicle for an experimental tricalcium silicate sealer, with the intention of developing a new biomaterial. Mouse undifferentiated dental pulp cells (OD-21) were cultured, and the effects of different association on cell proliferation and inflammatory cytokine production were investigated. Antimicrobial adhesion of Enterococcus faecalis to setting sealers at 2 h was evaluated. Polyethylene tubes containing experimental sealers and empty tubes were implanted into dorsal connective tissues of 12 male 3- to 4-months-old Wistar rats (250-280 g). After 7 and 30 days, the tubes were removed and processed for histological and immunohistochemical analyses. ANOVA followed by Bonferroni correction and ANOVA followed by Tukey test was used for parametric data and Kruskal-Wallis followed by Dunn for nonparametric (p < 0.05). Cell proliferation was dose-dependent, since all association were cytotoxic at higher concentrations; however, Ambroxol-PEG showed significantly higher cytotoxicity than other association (p < 0.05). In addition, irrespective of the association, no cytokine production was observed in vitro. Ambroxol-GLI reduced bacterial viability, whereas Ambroxol-PEG increased (p < 0.05). Histological examination showed no significant difference in the inflammatory response (p > 0.05) and mineralization ability in all association. Additionally, IL-1β and TNF-α were upregulated on Ambroxol-PEG in relation to Control at 07 days (p < 0.05). Ambroxol-GLI was the best vehicle for experimental tricalcium silicate sealer, as it promoted an increase in antimicrobial activity without altering the inflammatory response or mineralization ability.

Fungal immunity and pathogenesis in mammals versus the invertebrate model organism Galleria mellonella

In recent decades, Galleria mellonella (Lepidoptera: Pyralidae) have emerged as a model system to explore experimental aspects of fungal pathogenesis. The benefits of the G. mellonella model include being faster, cheaper, higher throughput and easier compared with vertebrate models. Additionally, as invertebrates, their use is subject to fewer ethical and regulatory issues. However, for G. mellonella models to provide meaningful insight into fungal pathogenesis, the G. mellonella-fungal interactions must be comparable to mammalian-fungal interactions. Indeed, as discussed in the review, studies suggest that G. mellonella and mammalian immune systems share many similarities, and fungal virulence factors show conserved functions in both hosts. While the moth model has opened novel research areas, many comparisons are superficial and leave large gaps of knowledge that need to be addressed concerning specific mechanisms underlying G. mellonella-fungal interactions. Closing these gaps in understanding will strengthen G. mellonella as a model for fungal virulence in the upcoming years. In this review, we provide comprehensive comparisons between fungal pathogenesis in mammals and G. mellonella from immunological and virulence perspectives. When information on an antifungal immune component is unknown in G. mellonella, we include findings from other well-studied Lepidoptera. We hope that by outlining this information available in related species, we highlight areas of needed research and provide a framework for understanding G. mellonella immunity and fungal interactions.