Effect of alkylphospholipids on Candida albicans biofilm formation and maturation

Sporotrichosis is a common mycosis caused by dimorphic fungi from the Sporothrix schenckii complex. In recent years, sporotrichosis incidence rates have increased in the Brazilian state of Rio de Janeiro, where Sporothrix brasiliensis is the species more frequently isolated from patients. The standard antifungals itraconazole and amphotericin B are recommended as first-line therapy for cutaneous/lymphocutaneous and disseminated sporotrichosis, respectively, although decreased sensitivity to these drugs in vitro was reported for clinical isolates of S. brasiliensis. Here, we evaluated the activity of the phospholipid analogue miltefosine -already in clinical use against leishmaniasis -towards the pathogenic yeast form of S. brasiliensis isolates with low sensitivity to itraconazole or amphotericin B in vitro. Miltefosine had fungicidal activity, with minimum inhibitory concentration (MIC) values of 1-2 mg ml "1 . Miltefosine exposure led to loss of plasma membrane integrity, and transmission electron microscopy (TEM) analysis revealed a decrease in cytoplasmic electron density, alterations in the thickness of cell wall layers and accumulation of an electron-dense material in the cell wall. Flow cytometry analysis using an antimelanin antibody revealed an increase in cell wall melanin in yeasts treated with miltefosine, when compared with control cells. The cytotoxicity of miltefosine was comparable to those of amphotericin B, but miltefosine showed a higher selectivity index towards the fungus. Our results suggest that miltefosine could be an effective alternative for the treatment of S. brasiliensis sporotrichosis, when standard treatment fails. Nevertheless, in vivo studies are required to confirm the antifungal potential of miltefosine for the treatment of sporotrichosis. INTRODUCTIONSporotrichosis is the most frequent subcutaneous mycosis in Latin America, and has high incidence rates in Brazil, especially in the Rio de Janeiro state, where zoonotic transmission prevails (Barros et al., 2010). This disease is caused by dimorphic fungal species from the Sporothrix schenckii complex (Marimon et al., 2007;, including Sporothrix brasiliensis, the most virulent species (ArrillagaMoncrieff et al., 2009;Fernandes et al., 2013) and the most prevalent in the clinical cases from the Rio de Janeiro state (Oliveira et al., 2011;Rodrigues et al., 2013a;Borba-Santos et al., 2014). In zoonotic transmission, sporotrichosis is mainly acquired by scratches, bites or direct contact with lesion secretion from contaminated animals, where yeasts are the infective forms (Rodrigues et al., 2013b).The 'gold standard' treatment for cutaneous and lymphocutaneous forms of sporotrichosis is itraconazole, while amphotericin B is the first-line drug of choice for disseminated forms of the disease (Kauffman et al., 2007). However, recent reports demonstrated that these drugs are less potent against S. brasiliensis isolates, which have high minimum inhibitory concentration (MIC) values in vitro for these antifungals (Ottonelli Stopiglia et a...

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“…3e). Alterations in cell wall components after miltefosine exposure were also described in C. albicans yeasts (Vila et al, 2013).…”

Section: Discussionmentioning

confidence: 80%

Miltefosine is active against Sporothrix brasiliensis isolates with in vitro low susceptibility to amphotericin B or itraconazole

Borba-Santos

Gagini

Ishida

et al. 2015

Journal of Medical Microbiology

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“…Fluconazole could not inhibit biofilm formation in a dose-dependent manner and could hardly affect mature biofilms. Similarly, Vila et al (22) reported that amphotericin B at 1ϫ MIC inhibited the development of biofilms but could not affect the maintenance of mature biofilms. In additions, our lab has reported the antibiofilm activities of pterostilbene and tetrandrine previously (18,20).…”

Section: Figmentioning

confidence: 92%

Activity of Sanguinarine against Candida albicans Biofilms

Zhong

et al. 2017

Antimicrob Agents Chemother

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Candida albicans biofilms show resistance to many clinical antifungal agents and play a considerable contributing role in the process of C. albicans infections. New antifungal agents against C. albicans biofilms are sorely needed. The aim of this study was to evaluate sanguinarine (SAN) for its activity against Candida albicans biofilms and explore the underlying mechanism. The MIC 50 of SAN was 3.2 g/ ml, while Ն0.8 g/ml of SAN could suppress C. albicans biofilms. Further study revealed that Ն0.8 g/ml of SAN could decrease cellular surface hydrophobicity (CSH) and inhibited hypha formation. Real-time reverse transcription-PCR (RT-PCR) results indicated that the exposure of C. albicans to SAN suppressed the expression of some adhesion-and hypha-specific/essential genes related to the cyclic AMP (cAMP) pathway, including ALS3, HWP1, ECE1, HGC1, and CYR1. Consistently, the endogenous cAMP level of C. albicans was downregulated after SAN treatment, and the addition of cAMP rescued the SAN-induced filamentation defect. In addition, SAN showed relatively low toxicity to human umbilical vein endothelial cells, the 50% inhibitory concentration (IC 50 ) being 7.8 g/ml. Collectively, the results show that SAN exhibits strong activity against C. albicans biofilms, and the activity was associated with its inhibitory effect on adhesion and hypha formation due to cAMP pathway suppression.

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“…We have recently described the promising antibiofilm activity of miltefosine against C. albicans central venous catheter biofilms (33). In the present study, we have evaluated the activity of miltefosine against planktonic cells and biofilms formed by Candida albicans clinical isolates resistant to fluconazole (34,35), demonstrated a low potential for the development of resistance to miltefosine, and reported susceptibility patterns for a series of C. albicans mutant strains mutated in different transcription factors (36).…”

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confidence: 97%

In Vitro Activity of Miltefosine against Candida albicans under Planktonic and Biofilm Growth Conditions and In Vivo Efficacy in a Murine Model of Oral Candidiasis

Vila

Chaturvedi

Rozental

et al. 2015

Antimicrob Agents Chemother

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The generation of a new antifungal against Candida albicans biofilms has become a major priority, since biofilm formation by this opportunistic pathogenic fungus is usually associated with an increased resistance to azole antifungal drugs and treatment failures. Miltefosine is an alkyl phospholipid with promising antifungal activity. Here, we report that, when tested under planktonic conditions, miltefosine displays potent in vitro activity against multiple fluconazole-susceptible and -resistant C. albicans clinical isolates, including isolates overexpressing efflux pumps and/or with well-characterized Erg11 mutations. Moreover, miltefosine inhibits C. albicans biofilm formation and displays activity against preformed biofilms. Serial passage experiments confirmed that miltefosine has a reduced potential to elicit resistance, and screening of a library of C. albicans transcription factor mutants provided additional insight into the activity of miltefosine against C. albicans growing under planktonic and biofilm conditions. Finally, we demonstrate the in vivo efficacy of topical treatment with miltefosine in the murine model of oropharyngeal candidiasis. Overall, our results confirm the potential of miltefosine as a promising antifungal drug candidate, in particular for the treatment of azole-resistant and biofilm-associated superficial candidiasis.T he recent elevated incidence of fungal infections is related to the indiscriminate use of broad-spectrum antibiotics and corticosteroids, the increase in the number of invasive medical procedures, and the AIDS epidemic. The persistence of these infections is usually associated with the fungal ability to form biofilms on implantable medical devices (1). Candida spp. can adhere and form biofilms on the surface of different medical devices (such as catheters, prostheses, pacemakers, and heart valves) and on the mucosal surface, leading to a superficial infection with a complex structure in which hyphae, pseudohyphae, and yeasts grow surrounded by a dense extracellular matrix, composed mainly of proteins, polysaccharides, and extracellular DNA (eDNA) (2). Hematogenous dissemination may occur due to the detachment of yeasts from the top layer of the biofilm, a phenomenon known as dispersion (3). Candida albicans is the third leading cause of infections related to the use of catheters (4, 5). Development of candidemia during hospitalization when central venous catheters are used can happen in 72% of cases in Latin America (6), and the worldwide mortality rate for catheter-related candidemia can reach 41% (7). Oropharyngeal candidiasis (OPC) is characterized by Candida growth as a biofilm over the tongue and oral mucosa. OPC has been described as the most frequent opportunistic fungal infection among HIV-positive patients, and it is estimated that more than 90% of these patients develop this infection at some time during the progression of their disease (8, 9).The increased resistance to antifungal agents is the main clinical complication associated with biofilm formation. ...

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Effect of alkylphospholipids on Candida albicans biofilm formation and maturation

Abstract: Promising antibiofilm activity was displayed by miltefosine and other alkylphosphocholine compounds, which could be considered a putative option for future treatment of candidaemia associated with biofilm formation, although further evaluation in in vivo systems is required.

Cited by 63 publications

References 37 publications

Miltefosine is active against Sporothrix brasiliensis isolates with in vitro low susceptibility to amphotericin B or itraconazole

Miltefosine is active against Sporothrix brasiliensis isolates with in vitro low susceptibility to amphotericin B or itraconazole

Activity of Sanguinarine against Candida albicans Biofilms

In Vitro Activity of Miltefosine against Candida albicans under Planktonic and Biofilm Growth Conditions and In Vivo Efficacy in a Murine Model of Oral Candidiasis

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