Bioactivity of new AmB-PMA nanoparticle in prophylaxis and treatment of transplant-related invasive aspergillosis

Abstract

Abstract: Aspergillus species are opportunistic mould pathogens that can cause a wide variety of pulmonary diseases. They are mainly caused by Aspergillus fumigatus (Munoz et al., 2006). Germination of conidia in hosts with a susceptible immune system is the first step in Aspergillus infection, and invasive aspergillosis (IA) is a major cause of mortality in transplant patients. Due to the increased occurrence of IA in high-risk populations, prophylaxis against IA is important. Prophylactic prevention of life threatening infections with drugs is now the preferred clinical strategy for these patients rather than treating the disease after it has become established. Inhaled amphotericin B (AmB) has potential for preventing IA and it has been reported to decrease the incidence of IA in solid organ transplant patients (Arthur et al., 2004). I have generated a new respiratory formulation of AmB (AmB-PMA) with a commercially available high purity, low polydispersity and non-toxic poly methacrylic acid sodium salt (PMA-Na). The chemical synthesis was optimized and showed that AmB-PMA complex was effective against A. fumigatus and was also less toxic than Fungizone in-vitro. The efficacy of AmB-PMA was determined in-vivo in BALB/c and C57BL/6 mice. Mice were infected intranasally with A. fumigatus CEA10 and treated with AmB-PMA by the nasal and nebulisation routes. In this thesis, the optimum routes of in-vivo administration, dosing regimens and treatment frequency were defined. Disease progression in A. fumigatus-infected BALB/c and C57BL/6 mice was monitored by histology, qPCR analysis of chemokine and cytokine responses in mouse lung, colony forming unit (CFU) and qPCR for Aspergillus ribosomal 28S rRNA. The results showed a significant reduction in CFU and DNA fungal load in AmB-PMA infected mice as compared to infected untreated mice. In addition, AmB-PMA could also affect cytokine production by increasing IFN-γ production and reducing MIP-1β, TNF-α and IL-10 as compared to infected untreated mice. However, the increase in IFN-γ production was not statistically significant when compared to infected untreated mice. My thesis demonstrates that a new low-cost AmB based PMA-Na polymer antifungal drug can be successfully given by the aerosol route to immuno-suppressed mice by nebulisation to prevent IA.