Aspirin and verapamil increase the sensitivity of Candida albicans to caspofungin under planktonic and biofilm conditions

Verapamil enhances the activity of Caspofungin against Cryptococcus neoformans， coinciding with inhibited Ca2+/CN pathway and damage to cell wall integrity

OBJECTIVES

Given the challenges posed by toxicity and drug resistance in the treatment of cryptococcal infections, we sought to explore the antifungal potential of verapamil (VER), a calcium channel blocker, against Cryptococcus neoformans (C. neoformans), and its potential synergy with antifungals, specifically caspofungin (CAS).

MATERIALS AND METHODS

In vitro and in vivo (Galleria mellonella) models were employed to assess VER's antifungal activity and its interaction with CAS. Mechanisms underlying the synergism were explored through analysis of cell wall integrity, membrane permeability, and gene expression related to the calcineurin pathway. Additionally, the influence of Ca2+ on chitin deacetylase activity was investigated.

RESULTS

VER exhibited a pronounced antifungal effect on C. neoformans and synergized with CAS, enhancing antifungal efficacy in Galleria mellonella. VER reduced chitosan content and disrupted cell wall integrity, evidenced by melanin leakage and fluorescence staining. VER+CAS modified membrane permeability, triggering intracellular ROS accumulation and mitochondrial membrane potential alterations. VER mitigated CAS-induced calcium fluctuations and downregulated calcineurin pathway genes. Furthermore, it was found that the enzyme activity of chitin deacetylase of C. neoformans is significantly influenced by the presence of Ca2+, suggesting that the use of VER may affect this activity.

CONCLUSIONS

The synergistic antifungal effect of VER and CAS represents a promising therapeutic strategy for cryptococcal infections. The multifaceted mechanisms, including disruption of cell wall integrity and modulation of membrane permeability, and regulation of intracellular calcium signaling pathways, offer new insights into antifungal drug development.

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.

In Vitro Effect of Three-Antibiotic Combinations plus Potential Antibiofilm Agents against Biofilm-Producing Mycobacterium avium and Mycobacterium intracellulare Clinical Isolates

Patients with chronic pulmonary diseases infected by Mycobacterium avium complex (MAC) often develop complications and suffer from treatment failure due to biofilm formation. There is a lack of correlation between in vitro susceptibility tests and the treatment of clinical isolates producing biofilm. We performed susceptibility tests of 10 different three-drug combinations, including two recommended in the guidelines, in biofilm forms of eight MAC clinical isolates. Biofilm developed in the eight isolates following incubation of the inoculum for 3 weeks. Then, the biofilm was treated with three-drug combinations with and without the addition of potential antibiofilm agents (PAAs). Biofilm bactericidal concentrations (BBCs) were determined using the Vizion lector system. All selected drug combinations showed synergistic activity, reducing BBC values compared to those treated with single drugs, but BBC values remained high enough to treat patients. However, with the addition of PAAs, the BBCs steadily decreased, achieving similar values to the combinations in planktonic forms and showing synergistic activity in all the combinations and in both species. In conclusion, three-drug combinations with PAAs showed synergistic activity in biofilm forms of MAC isolates. Our results suggest the need for clinical studies introducing PAAs combined with antibiotics for the treatment of patients with pulmonary diseases infected by MAC.

Antifungal activity and potential mechanism of action of caspofungin in combination with ribavirin against Candida albicans

The number of invasive fungal infections has increased dramatically, resulting in high morbidity and mortality among immunocompromised patients. With increasing use of caspofungin (CAS), resistant strains have emerged frequently and led to limitations in the treatment of patients with severe invasive Candida albicans infections. Combination therapy is an important method to deal with this issue. As such, this study investigated the activity of CAS in combination with ribavirin (RBV) against C. albicans. The results of this in-vitro study showed that the minimum inhibitory concentrations (MICs) of CAS and RBV when they were used as monotherapy were 0.5-1 μg/mL and 2-8 μg/mL, respectively, while the MIC of CAS decreased from 0.5-1 μg/mL to 0.0625-0.25 μg/mL when used in combination with RBV, with a fractional inhibitory concentration index (FICI) ≤0.5. In addition, the RBV + CAS combination group displayed synergistic effects against C. albicans biofilm over 4 h; the sessile MIC (sMIC) of CAS decreased from 0.5-1 µg/mL to 0.0625-0.25µg/mL and the sMIC of RBV decreased from 4-16 µg/mL to 1-2 µg/mL, with FICI <0.5. The survival of C. albicans-infected Galleria mellonella was prolonged, the fungal burden was decreased, and the area of tissue damage was reduced after combination therapy. Further study showed that the mechanisms of action of the synergistic effect were related to the inhibition of biofilm formation, the inhibition of hyphal growth, and the activation of metacaspases, but were not related to the accumulation of reactive oxygen species. It is hoped that these findings will contribute to the understanding of drug resistance in C. albicans, and provide new insights for the application of RBV.

Aspirin and Infection: A Narrative Review

Acetylsalicylic acid (ASA) is one of the most commonly used drugs in the world. It derives from the extract of white willow bark, whose therapeutic potential was known in Egypt since 1534 BC. ASA’s pharmacological effects are historically considered secondary to its anti-inflammatory, platelet-inhibiting properties; however, human studies demonstrating a pro-inflammatory effect of ASA exist. It is likely that we are aware of only part of ASA’s mechanisms of action; moreover, the clinical effect is largely dependent on dosages. During the past few decades, evidence of the anti-infective properties of ASA has emerged. We performed a review of such research in order to provide a comprehensive overview of ASA and viral, bacterial, fungal and parasitic infections, as well as ASA’s antibiofilm properties.

Cotreatment with Aspirin and Azole Drugs Increases Sensitivity of Candida albicans in vitro

Purpose

This study aimed to investigate the effects of aspirin (acetyl salicylic acid [ASA]) combined with fluconazole (FCA), itraconazole (ITR), or voriconazole (VRC) on Candida albicans under planktonic and biofilm conditions.

Methods

A total of 39 clinical C. albicans strains were used to perform the in vitro drug sensitivity assay under different conditions using the M27-A4 broth microdilution method. The minimal inhibitory concentrations (MICs) and fractional inhibitory concentration index (FICI) values were calculated. C. albicans ZY23 was chosen for the further analyses.

Results

Under planktonic conditions, the half maximal MIC (MIC₅₀) values of FCA, ITR, and VRC were 64-0.5 μg/mL, 32-0.0625 μg/mL, and 16-0.125 μg/mL, respectively, when applied, whereas in combination with ASA, the values decreased to 32-0.25 μg/mL, 8-0.0313 μg/mL, and 8-0.0313 μg/mL, respectively. Under biofilm conditions, FCA, ITR, or VRC alone showed MIC₅₀ values of 128-8 μg/mL, 32-4 μg/mL, and 32-0.5 μg/mL, whereas in combination with ASA the values were decreased to 32-0.5 μg/mL, 16-0.5 μg/mL, and 8-0.0625 μg/mL, respectively. Analysis of the FICI showed that the sensitization rate of ASA to FCA, ITR, and FCA under planktonic conditions was 43.59%, whereas the sensitization rates of ASP to FCA, ITR, and FCA under biofilm conditions were 46.15%, 46.15%, and 48.72%, respectively. Additionally, the time-growth and time-kill curves of C. albicans ZY23 further verified the synergistic effects of ASA on azole drugs.

Conclusion

ASA may act as an enhancer of the inhibitory effects of azole drugs on the growth of clinical C. albicans under planktonic and biofilm conditions.