Caspofungin primes the immune response of the larvae of Galleria mellonella and induces a non-specific antimicrobial response

Abstract

The echinocandins (e.g. caspofungin) function by inhibiting the synthesis of 1,3-b-glucan in the fungal cell wall. While the potent antifungal activity of caspofungin has been well characterized in mammals, this study investigated the in vivo antifungal effect of caspofungin using larvae of the insect Galleria mellonella. Caspofungin was successful in increasing the survival of larvae that were inoculated with Candida albicans 1 h before the drug was administered, particularly when a concentration of 0.19 mg ml "1 was used. Pre-injecting larvae with caspofungin also increased their survival when they were inoculated with either Staphylococcus aureus or C. albicans. Caspofungin administration resulted in an increase in the number of circulating immune cells (haemocytes), an increase in the expression of the genes encoding IMPI and transferrin, and an increase in the expression of a number of proteins (identified by liquid chromatography-mass spectrometry) some of which have immune functions. This work indicates that administration of caspofungin can increase the survival of infected G. mellonella larvae, and this is due to the antifungal properties of caspofungin and also to the ability of caspofungin to prime the insect's immune response.

Assessment of in vivo antimicrobial activity of the carbene silver(I) acetate derivative SBC3 using Galleria mellonella larvae

“…Insects have the benefit of being inexpensive to purchase and house, and can give results in 24-48 h. Insect can also be used to evaluate the in vivo activity of antimicrobial drugs (Hamamoto et al 2004;) but caution must be exercised in their use as the introduction of foreign material into the insect haemoceol can provoke a non-specific immune response (Mowlds et al 2010;Kelly and Kavanagh 2011).…”

“…SBC3 does not provoke an enhanced immune response as indicated by the lack of an increase in the haemocyte density and the expression of antimicrobial and immune related peptides. A number of proteins were shown to decrease in abundance in larvae that received SBC3 and these included carboxylesterase (spot 3, Table 1) which has physiological functions in neurotransmitter degradation, hormone and pheromones specific metabolism, detoxification, defense and behavior (Vogt et al 1985;Taylor and Radic 1994), 27 kDa haemolymph protein (spot 2) which is secreted into the haemolymph as a signal molecule (Kelly and Kavanagh 2011) and apolipophorin-3 (spot 8) which functions in the innate immune response (Gupta et al 2010). Spot 6, hypothetical protein YQE_03765 partial, was increased in abundance in larvae that received SBC3 and functions as a death domain protein with roles in apoptosis, immune defense, and immune signalling (Lahm et al 2003).…”

“…Previous work has demonstrated that introduction of selected agents (e.g. silver nitrate, caspofungin, b-glucan) into the haemocoel of G. mellonella larvae can prime the immune response and lead to an increase in the density of circulating haemocytes and in the expression of antimicrobial and immune related peptides (Rowan et al 2009;Kelly and Kavanagh 2011;Mowlds et al 2010). In order to exclude the possibility that the observed in vivo antimicrobial activity of SBC3 was due to the increased density of immune cells in the larvae, the density of circulating haemocytes in larvae was assessed.…”

“…The insect immune system shows many similarities to the innate immune system of mammals (Kavanagh and Reeves 2004;Browne et al 2013) and, as a consequence, insects have been used as models to measure the virulence of microbial pathogens (Fuchs and Mylonakis 2006) and to evaluate the potency of antimicrobial drugs (Hamamoto et al 2004;Rowan et al 2009) and give results consistent with those that can be obtained using mammals (Jander et al 2000;Brennan et al 2002). A number of insect species can be employed for evaluating the in vivo activity of novel antimicrobial drugs (Kavanagh and Fallon 2010) and larvae of the Greater Wax Moth, Galleria mellonella are now widely used in this capacity (Kelly and Kavanagh 2011;Rowan et al 2009;Desbois and Coote 2012). This paper describes the antimicrobial effects of SBC3 against the bacterium S. aureus and the yeast Candida albicans in vitro and demonstrates the in vivo activity and toxicity of SBC3 against these two pathogens in G. mellonella larvae.…”

Histological Observation and Expression Patterns of antimicrobial peptides during Fungal Infection in Musca domestica (Diptera: Muscidae) Larvae

“…C. albicans was cultivated in Sabouraud dextrose agar (SDA) and its cell suspension was prepared by inoculating a single colony in Sabouraud dextrose broth (SDB) at 37°C for 12 h with agitation (Kelly and Kavanagh 2011). Fungus entering the logarithmic growth phase was selected for infection experiments.…”