Effect of the Echinocandin Caspofungin on Expression of Candida albicans Secretory Aspartyl Proteinases and Phospholipase In Vitro

Abstract

Although the echinocandin caspofungin primarily inhibits the synthesis of cell wall 1,3-␤-D-glucan, its fungicidal activity could also potentially perturb the expression of virulence factors involved in the ability of Candida albicans to cause infection. Expression of the C. albicans secretory aspartyl proteinase (SAP) and phospholipase B (PLB) virulence genes was determined by reverse transcription-PCR after the addition of caspofungin to cells grown for 15 h in Sabouraud dextrose broth. In cells that remained viable, expression of SAP1 to SAP3, SAP7 to SAP9, and PLB1 was unaltered after exposure to fungicidal concentrations (4 to 16 g/ml) of caspofungin over a period of 7 h. However, expression of SAP5 increased steadily beginning 1 h after exposure to caspofungin. These results indicate that caspofungin is rapidly fungicidal against C. albicans, before any suppression of SAP or PLB1 gene expression can occur.The cyclic lipopeptide pneumocandins and echinocandins and the glycolipid papulacandins are members of a new class of antifungal agents which exert their activity by noncompetitive inhibition of fungal 1,3-␤-D-glucan synthase (5,17,22,30,37). This enzyme is essential for the synthesis of cell wall glucan which provides structural integrity and osmotic stability for fungi but is not found in cells from higher eukaryotes including humans. Disruption of cell wall structure by inhibition of glucan synthesis results in osmotic instability and lysis of the fungal cell (12, 37). Caspofungin (MK-0991) is a water-soluble semisynthetic amine derivative of the natural product pneumocandin Bo (17,26,37), which in turn is a fermentation product derived from the fungus Glarea lozoyensis (9). Caspofungin was developed as a potential antifungal and anti-Pneumocystis agent (17,26,37). In vitro, caspofungin is fungicidal against Candida species, including azole-resistant species, and is fungistatic against Aspergillus species (6,8,15,28,33,39,45). However, it is inactive against Fusarium, Rhizopus, Trichosporon, and Cryptococcus neoformans (8,15,28,39). In addition to prolonging survival in mouse models of disseminated candidiasis and aspergillosis (1,2,20,21), caspofungin has recently shown promising clinical activity for the treatment of lifethreatening infections caused by Candida and Aspergillus species (46; J. Maertens, I. Raad, C.

Assessing the antifungal activity and toxicity profile of amphotericin B lipid complex (ABLC; Abelcet®) in combination with caspofungin in experimental systemic aspergillosis

“…This result may be due to Caspofungin's ability to increase amphotericin B‐induced renal toxicity. Ripeau et al have recently reported that Caspofungin can increase the expression of Candida albicans secretory proteinase 5 28. Secretory proteinases may selectively release active amphotericin B from the ABLC at sites of fungal infection in a similar way as fungal cell‐derived phospholipases32 resulting in more active amphotericin B available to not only cause damage to fungal cells but also to surrounding renal cells.…”

Aspartic Peptidase Inhibitors as Potential Bioactive Pharmacological Compounds Against Human Fungal Pathogens

“…The C. albicans isolates from the HIV-positive group that were characterized by higher levels of peptidase activity were also less susceptible to the widely used azole antifungal agents ketoconazole and fluconazole (Ollert et al 1995). C. albicans strains exposed to subinhibitory concentrations of antifungals belonging to the azole, echinocandin, and pyrimidine analog classes showed an elevated activity of Sap2 in the culture filtrates (Wu et al 2000;Ripeau et al 2002). In addition, the expression of SAP2 and activity of the secreted Sap2 gene product was upregulated in fluconazole-exposed yeast cells (Copping et al 2005).…”

Novel antifungal agents: a patent review (2011 – present)

“…CPF (Cancidas Ò , Merck Sharp & Dohme, Whitehouse Station, NJ, USA) is derived from pneumocandin B, which in turn was isolated from the fungus Glarea lozoyensis [62,63]. ANDF (Eraxis Ò , Pfizer, New York, USA) is a semisynthetic product of echinocandin B, which is a fermentation product of the mold A. nidulans.…”