Involvement of the pleiotropic drug resistance response, protein kinase C signaling, and altered zinc homeostasis in resistance of Saccharomyces cerevisiae to diclofenac

Can nonsteroidal anti-inflammatory drugs (NSAIDs) be repurposed for fungal infection?

Nonsteroidal anti-inflammatory drugs (NSAIDs) are an important class of anti-inflammatory drugs widely used for the treatment of musculoskeletal disorders, mild-to-moderate pain, and fever. This review aimed to explain the functional role and possible mechanisms of the antifungal effects of NSAIDs alone or in combination with antifungal drugs in vitro and in vivo. Several studies reported that NSAIDs such as aspirin, ibuprofen, diclofenac, indomethacin, ketorolac, celecoxib, flurbiprofen, and nimesulide had antifungal activities in vitro, either fungistatic or fungicidal, against different strains of Candida, Aspergillus, Cryptococcus, Microsporum, and Trichophyton species. These drugs inhibited biofilm adhesion and development, and yeast-to-hypha conversion which may be related to a prostaglandin E2 (PGE2)/PGEx-dependent mechanism. Modulating PGE2 levels by NSAIDs during fungal infection can be introduced as a possible mechanism to overcome. In addition, some important mechanisms of the antifungal activities of NSAIDs and their new derivatives on fungi and host immune responses are summarized. Overall, we believe that using NSAIDs along with classical antifungal drugs has the potential to be investigated as a novel therapeutic strategy in clinical studies. Furthermore, combination therapy can help manage resistant strains, increase the efficacy of antifungal drugs, and reduce toxicity.

Antioxidant properties of the Lebanese plant Iris x germanica L. crude extracts and antagonism of chlorpromazine toxicity on Saccharomyces cerevisiae

Iris x germanica L., which belongs to the Iridaceae family, has been reported in the literature for its antioxidant properties in acellular chemical-antioxidant assays. Chlorpromazine (CPZ) is an antipsychotic drug known to cause adverse reactions in humans. Oxidative stress is among the main mechanisms by which CPZ exerts its toxicity in animal cell models as well as in the yeast Saccharomyces cerevisiae. In this study we investigated the protective effects of I. germanica L. crude extracts against CPZ toxicity. We demonstrated that methanolic extracts from rhizome (R-M), leaf (L-M) and flower (Fl-M) had potent antioxidant activity by scavenging the free radical DPPH, with half-maximal effective concentrations (EC₅₀) 193, 107, and 174 µg/mL, respectively. R-M, L-M and Fl-M at doses up to 1000 µg/mL, didn't affect yeast cell growth. In addition, we demonstrated for the first time that L-M at 1000 µg/mL and R-M at all tested doses counteracted CPZ toxicity, probably by promoting yeast cell antioxidant agents. The R-M capacity to counteract CPZ toxicity was lost in the yeast strain mutant in catalase-encoding gene (Cta1), while strains mutant in Sod2, Skn7 and Rap1 showed mild or full R-M-induced protective effect against CPZ toxicity. Our results demonstrated that I. germanica L. R-M extract counteracted CPZ toxicity in the yeast cell model. Further studies are planned to isolate the involved bioactive compounds and identify the involved genes and the antioxidant agents.

Interaction of cigarette smoke condensate and some of its components with chlorpromazine toxicity on Saccharomyces cerevisiae

Chlorpromazine (CPZ) is an antipsychotic phenothiazine which is still commonly prescribed though it causes idiosyncratic toxicity such as cholestasis. CPZ toxicity mechanisms involve oxidative stress among others. Cigarette smoke (CS) causes deleterious effects through diverse mechanisms such as oxidative stress. CS alters drug metabolizing enzymes expression and drug transporters expression and activity in animal cell models as well as in Saccharomyces cerevisiae. CS therefore alters pharmacokinetic and pharmacodynamics of many drugs including CPZ and caffeine whose toxicity is promoted by CS condensate (CSC). CSC interaction with CPZ toxicity deserves investigation. In this study, CSC exerted mild toxicity on Saccharomyces cerevisiae which resisted to this chemical stress after several hours. CPZ toxicity on yeast was dose-dependent and the cells resisted to CPZ up to 40 µM after 24 h of treatment. Yeast cells treated simultaneously with CPZ and a nontoxic CSC dose were less sensitive to CPZ. CSC probably triggers cross-resistance to CPZ. Using Sod1 mutant strain, we showed that this gene is potentially involved in the potential cross-resistance. Other genes encoding stress-related transcription factors could be involved in this process. Nicotine and cadmium chloride, which caused a dose-dependent toxicity individually, acted with CPZ in an additive or synergistic manner in terms of toxicity. Although our results cannot be extrapolated to humans, they clearly show that CSC and its components interact with CPZ toxicity.

Development of a high throughput methodology to screen cathinones' toxicological impact

Current trend of novel psychoactive substances (NPS) among teenagers is posing new clinical, scientific and forensic societal questions. Synthetic cathinones are among the most consumed groups of NPS appearing on the street market and internet on a regular basis. The properties of these substances change regularly, due to structural modification to circumvent legislation. This practice makes almost impossible to characterize its toxicological profiles on an acceptable time scale, mostly due to the time-consuming experiments that must be held in animal models or human cells by standard methods. Such an issue demands the development of a rapid and inexpensive methodology to be used as a high-throughput screening of cathinones' toxicity. The yeast Saccharomyces cerevisiae shares highly conserved molecular and cellular mechanisms with human cells and has been used before for pharmacological drugs. In the present work it is proposed to use S. cerevisiae growth curves as a high throughput screening method to profile synthetic cathinones toxicity in a short time scale. The results obtained by S. cerevisiae growth curves analysis were compared to differentiated SH-SY5Y human neuronal cells and similar responses were found. The screening tool methodology has shown able to prioritize the most toxics NPS and can be useful for early warning programs on NPS.

Tuning the Sensitivity of the PDR5 Promoter-Based Detection of Diclofenac in Yeast Biosensors

The commonly used drug diclofenac is an important environmental anthropogenic pollutant. Currently, detection of diclofenac is mainly based on chemical and physical methods. Here we describe a yeast biosensor that drives the diclofenac-dependent expression of a recombinant fluorescent protein from the authentic promoter of the PDR5 gene. This key component of the pleiotropic drug response encodes a multidrug transporter that is involved in cellular detoxification. We analyse the effects on diclofenac sensitivity of artificial PDR5 promoter derivatives in wild-type and various yeast mutant strains. This approach enabled us to generate sensor strains with elevated drug sensitivity.

Prior knowledge guided active modules identification: an integrated multi-objective approach

BACKGROUND

Active module, defined as an area in biological network that shows striking changes in molecular activity or phenotypic signatures, is important to reveal dynamic and process-specific information that is correlated with cellular or disease states.

METHODS

A prior information guided active module identification approach is proposed to detect modules that are both active and enriched by prior knowledge. We formulate the active module identification problem as a multi-objective optimisation problem, which consists two conflicting objective functions of maximising the coverage of known biological pathways and the activity of the active module simultaneously. Network is constructed from protein-protein interaction database. A beta-uniform-mixture model is used to estimate the distribution of p-values and generate scores for activity measurement from microarray data. A multi-objective evolutionary algorithm is used to search for Pareto optimal solutions. We also incorporate a novel constraints based on algebraic connectivity to ensure the connectedness of the identified active modules.

RESULTS

Application of proposed algorithm on a small yeast molecular network shows that it can identify modules with high activities and with more cross-talk nodes between related functional groups. The Pareto solutions generated by the algorithm provides solutions with different trade-off between prior knowledge and novel information from data. The approach is then applied on microarray data from diclofenac-treated yeast cells to build network and identify modules to elucidate the molecular mechanisms of diclofenac toxicity and resistance. Gene ontology analysis is applied to the identified modules for biological interpretation.

CONCLUSIONS

Integrating knowledge of functional groups into the identification of active module is an effective method and provides a flexible control of balance between pure data-driven method and prior information guidance.

Comparison of the Antimicrobial Properties of Chitosan Oligosaccharides (COS) and EDTA against Fusarium fujikuroi Causing Rice Bakanae Disease

Bakanae disease is a destructive rice disease in South Korea caused by Fusarium fujikuroi infection. Chemical fungicides have been used to manage the disease, but the emergence of fungicide-resistant strains has gradually increased. Two chelating agents, chitosan oligosaccharides (COS) and ethylenediaminetetraacetatic acid (EDTA), are well known as biosafe and biocompatible antimicrobial agents. In this study, we compared the actions of COS and EDTA to gain a better understanding of the underlying antimicrobial activities and to evaluate them as eco-friendly fungicides against F. fujikuroi. While COS exhibited a rapid fungicidal effect on hyphal growing cells within 5 min, EDTA had a fungistatic effect on reversible growth inhibition. Scanning electron microscopy revealed that COS treatment resulted in pore-formation and cellular leakage along the growing hyphae, whereas EDTA caused no significant morphological changes. COS activity was greatly suppressed by the addition of Ca(2+) to the medium, and EDTA action was largely suppressed by Mn(2+) and slightly by Ca(2+), respectively. Taken together, these results indicated that two chelating agents, COS and EDTA, have different modes of antimicrobial action on F. fujikuroi. Thus, the combination of chelating agents having different modes of action might be an effective disease management strategy to prevent or delay the development of fungicide-resistant strains.

A novel murine model of Fusarium solani keratitis utilizing fluorescent labeled fungi

Fungal keratitis is a common disease that causes blindness. An effective animal model for fungal keratitis is essential for advancing research on this disease. Our objective is to develop a novel mouse model of Fusarium solani keratitis through the inoculation of fluorescent-labeled fungi into the cornea to facilitate the accurate and early identification and screening of fungal infections. F. solani was used as the model fungus in this study. In in vitro experiment, the effects of Calcofluor White (CFW) staining concentration and duration on the fluorescence intensity of F. solani were determined through the mean fluorescence intensity (MFI); the effects of CFW staining on the growth of F. solani were determined by the colony diameter. In in vivo experiment, the F. solani keratitis mice were induced and divided into a CFW-unlabeled and CFW-labeled groups. The positive rate, corneal lesion score and several positive rate determination methods were measured. The MFIs of F. solani in the 30 μg/ml CFW-30 min, 90 μg/ml CFW-10 min and 90 μg/ml CFW-30 min groups were higher than that in the 10 μg/ml CFW-10 min group (P < 0.01). Compared with the 30 μg/ml CFW-30 min group, only the 90 μg/ml CFW-30 min group showed higher MFI (P < 0.05). No significant difference was observed in the colony diameter in the CFW unstained group compared with that in the 10, 30, 90, 270, or 810 μg/ml CFW groups stained for either 10 or 30 min (P > 0.05). No significant differences (P > 0.05) were observed for the positive rate or the corneal lesion scores between the CFW-unlabeled and the CFW-labeled group. On day 1 and 2, the positive rates of the infected corneas in the scraping group were lower than those in the fluorescence microscopy group (P < 0.05). On day 3, these observe methods showed no significant difference (P > 0.05). Thus, these experiments established a novel murine model of F. solani keratitis utilizing fluorescent labeled fungi. This model facilitates the accurate identification and screening of fungal infections during the early stages of fungal keratitis and provides a novel and reliable technology to study the fungal keratitis.

Differential involvement of mitochondrial dysfunction, cytochrome P450 activity, and active transport in the toxicity of structurally related NSAIDs

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used in the treatment of pain and inflammation. However, this group of drugs is associated with serious adverse drug reactions. Previously, we studied the mechanisms underlying toxicity of the NSAID diclofenac using Saccharomycescerevisiae as model system. We identified the involvement of several mitochondrial proteins, a transporter and cytochrome P450 activity in diclofenac toxicity. In this study, we investigated if these processes are also involved in the toxicity of other NSAIDs. We divided the NSAIDs into three classes based on their toxicity mechanisms. Class I consists of diclofenac, indomethacin and ketoprofen. Mitochondrial respiration and reactive oxygen species (ROS) play a major role in the toxicity of this class. Metabolism by cytochrome P450s further increases their toxicity, while ABC-transporters decrease the toxicity. Mitochondria and oxidative metabolism also contribute to toxicity of class II drugs ibuprofen and naproxen, but another cellular target dominates their toxicity. Interestingly, ibuprofen was the only NSAID that was unable to induce upregulation of the multidrug resistance response. The class III NSAIDs sulindac, ketorolac and zomepirac were relatively non-toxic in yeast. In conclusion, we demonstrate the use of yeast to investigate the mechanisms underlying the toxicity of structurally related drugs.