Therapy of Murine Pulmonary Aspergillosis with Antibody-Alliinase Conjugates and Alliin

Abstract

Aspergillus fumigatus is an opportunistic fungal pathogen responsible for invasive aspergillosis in immunocompromised individuals. The high morbidity and mortality rates as well as the poor efficacy of antifungal agents remain major clinical concerns. Allicin (diallyl-dithiosulfinate), which is produced by the garlic enzyme alliinase from the harmless substrate alliin, has been shown to have wide-range antifungal specificity. A monoclonal antibody (MAb) against A. fumigatus was produced and chemically ligated to the enzyme alliinase. The purified antibody-alliinase conjugate bound to conidia and hyphae of A. fumigatus at nanomolar concentrations. In the presence of alliin, the conjugate produced cytotoxic allicin molecules, which killed the fungus. In vivo testing of the therapeutical potential of the conjugate was carried out in immunosuppressed mice infected intranasally with conidia of A. fumigatus. Intratracheal (i.t.) instillation of the conjugate and alliin (four treatments) resulted in 80 to 85% animal survival (36 days), with almost complete fungal clearance. Repetitive intratracheal administration of the conjugate and alliin was also effective when treatments were initiated at a more advanced stage of infection (50 h). The fungi were killed specifically without causing damage to the lung tissue or overt discomfort to the animals. Intratracheal instillation of the conjugate without alliin or of the unconjugated monoclonal antibody significantly delayed the death of the infected mice, but only 20% of the animals survived. A limitation of this study is that the demonstration was achieved in a constrained setting. Other routes of drug delivery will be investigated for the treatment of pulmonary and extrapulmonary aspergillosis.

Antibacterial Activity of Ethanol and Aqueous Extracts of Garcinia Kola and Allium Sativum against Some Respiratory Pathogens: Alternative Antimicrobials?

“…The latter is known to have serious post infection consequences [24] . The plants are also used as anti mycotic and anti-cancer agents [25,26] . The ultimate aim will be the purification and concentration of the active ingredients of both plants as drugs against susceptible organisms.…”

Untitled

“…Targeting is achieved by conjugating the enzyme to site-specific antibodies. Such conjugates produced pronounced therapeutic effects in experimental animals bearing various types of tumor [15][16][17] or suffering from pulmonary aspergillosis [18] when injected prior to administration of alliin.…”

The protective role of immunoglobulins in fungal infections and inflammation

“…fumigatus activities in vitro [80]. In a murine pulmonary aspergillosis model, A. fumigatus-specific IgM MAb-alliinase conjugate enhanced survival of immunosuppressed mice by causing specific killing of A. fumigatus without damaging the lung tissue [81].…”