Mouse Model Of Invasive Pulmonary Aspergillosis Research Articles

In vivo pharmacodynamic characterization of a next-generation polyene, SF001, in the invasive pulmonary aspergillosis mouse model.

SF001 is a next-generation polyene antifungal drug in development, designed to have increased specificity to fungal ergosterol, which is absent in humans, and decreased binding to cholesterol. SF001 demonstrates long-acting, potent, broad-spectrum fungicidal activity. The goal of the current study was to determine the pharmacodynamic index and target of SF001 in an immunocompromised mouse model of invasive pulmonary aspergillosis against six Aspergillus fumigatus isolates. Minimum inhibitory concentration (MIC) values ranged from 0.5 to 2.0 mg/L. Plasma and epithelial lining fluid (ELF) pharmacokinetics were performed following single intraperitoneal doses of 1, 4, 16, and 64 mg/kg. Treatment efficacy was assessed with each of the six fungal isolates using daily doses of SF001 ranging from 0.25 to 64 mg/kg/day over a 96-h treatment duration. Efficacy was assessed by A. fumigatus quantitative PCR of conidial equivalents from lung homogenates. Nonlinear regression analysis using the Hill equation demonstrated that the 24-h exposure-response relationships for both plasma and ELF area under the concentration/MIC and Cmax/MIC ratios were strong and relatively similar [coefficient of determination (R2) = 0.74-0.75). Exposure-response relationships included a median plasma 24-h Cmax/MIC target for stasis and 1-log kill endpoint of 0.5 and 0.6, respectively. The present studies demonstrated in vitro and in vivo SF001 potency against A. fumigatus. These results have potential relevance for SF001 clinical dose selection and evaluation of susceptibility breakpoints.

Roles of Host Phospholipase D during Aspergillus fumigatus Infection in Mice

Objective: Aspergillus fumigatus infection in the lungs is accompanied by the recruitment of innate immune cells, phagocytosis, and the release of inflammatory factors. Phospholipase D (PLD) is a key regulator of cell migration and phagocytosis, but the effect of PLD deficiency on antifungal infection in animals is unknown. This study aims to investigate the impact of PLD on the host immune response to A. fumigatus infection under either immunocompetent or immunosuppressed status. Methods: The invasive pulmonary aspergillosis mouse model was created using a modified protocol with immunosuppression by steroids. For collection of bronchoalveolar lavage fluid (BALF) from mice, the lungs were washed eight times with 0.5 ml of PBS. Total cell counts in BALF were determined using a Coulter Counter. The content of alveolar macrophages, neutrophils, and monocytes in BALF was examined by flow cytometry and analyzed by FlowJo V10 software. Multiplex immunoassays were used to determine the concentrations of inflammatory cytokines in BALF. Results: In immunocompetent mice, alveolar macrophages were the major cell population in BALF after A. fumigatus infection, and a number of neutrophils and monocytes were recruited in the alveoli. Loss of both pld1 and pld2 genes did not affect the content of alveolar macrophages, neutrophils, or monocytes in BALF. Under immunosuppression induced by hydrocortisone acetate, pld1-/-pld2-/- mice showed higher mortality after A. fumigatus infection and had a higher fungal burden and much lower number of prominent focal areas of dense inflammatory infiltrates in lung tissue than wild type mice. Moreover, interleukin (IL)-12p40 significantly decreased, and IL-10 markedly increased, in BALF from pld1 -/- pld2 -/- mice after infection. Conclusion: Our findings revealed that, during A. fumigatus infection, deficiency in both pld1 and pld2 in mice was not conducive to the infiltration of inflammatory cells into lung tissue but promoted the release of IL-10 and blocked the release of IL-12, thereby increasing fungal burden and mortality.

Therapeutic Potential of Green Synthesized Gold Nanoparticles Using Extract of Leptadenia hastata against Invasive Pulmonary Aspergillosis.

Gold nanoparticles are widely used in the biomedical field for the treatment of several diseases, including cancer, inflammatory diseases, and immune system disorders, due to their distinctive physicochemical characteristics. In this study, we investigated the therapeutic potential of green synthesized gold nanoparticles using ethanolic leaf extract of Leptadenia hastata (LH-AuNPs) against invasive pulmonary aspergillosis (IPA) in mice. UV/visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and zeta potential were used to characterize the biofabricated LH-AuNPs. Antifungal activity of LH-AuNPs was determined by MTT assay, (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide), time-kill assay, and radial growth inhibition. TEM and SEM were used to examine the mode of the antifungal action of LH-AuNPs. The in vivo activity of LH-AuNPs against IPA was studied using a well-established IPA mouse model. LH-AuNPs excreted antifungal activity against Aspergillus fumigatus with MIC 64 µg/mL and inhibited the radial growth of A. fumigatus by 30% compared to the control. LH-AuNPs caused distortion and collapse of fungal hyphae and deterioration of cell walls. Interestingly, LH-AuNPs did not display any cytotoxicity on cultured primary bone marrow stem cells (BMSCs) or A549 human lung cell line in vitro at MIC concentration. IPA mice treated with LH-AuNPs displayed significant lung tissue repair without any in vivo cytotoxicity. LH-AuNPs administration showed significant suppression of fungal burden and gliotoxin production in the lung. In addition, LH-AuNPs inhibited IPA-induced pro-inflammatory cytokines production, including interleukin-1 (IL-1), interleukin-17 (IL-17), and tumor necrosis factor-alpha (TNF-α), and reduced oxidative stress in lung. In conclusion, our data provide LH-AuNPs as a novel nanoparticle therapy for IPA.

MTOR Modulates CD8+ T Cell Differentiation in Mice with Invasive Pulmonary Aspergillosis.

CD8+ T cells are a vital component of the adaptive immune system and important for eliminating intracellular pathogens. Notably, mTOR activity is associated with CD8+ T effector memory (Tem) cell differentiation in fungal infections. This study investigates the molecular mechanisms of CD8+ Tem cell proliferation and differentiation mediated by the mTOR pathway in immunosuppressed mice with invasive pulmonary aspergillosis (IPA). We first established the immunosuppressed IPA mouse model, then mice were subjected to rapamycin treatment daily or interleukin (IL)-12 treatment every other day. Lung tissues and blood samples were obtained seven days later. Aspergillus fumigatus was cultured from the lung tissue of mice inoculated with A. fumigatus spores. After IL-12 treatment, the expression of mTOR and its downstream signaling molecule S6 kinase, number of CD8+ Tem cells and interferon-γ expression were significantly increased, while they were significantly decreased after treatment with rapamycin. Additionally, IL-12 treatment induced T-bet but inhibited Eomesodermin expression, while the opposite was seen when the mTOR pathway was blocked by rapamycin. In conclusion, we found that the mTOR pathway induced CD8+ T cell proliferation and differentiation by regulating T-bet and Eomesodermin expression, which significantly influenced immune regulation during IPA and enhanced the immune response against fungal infection.

Role of Triggering Receptor Expressed on Myeloid Cell-1 Expression in Mammalian Target of Rapamycin Modulation of CD8+ T-cell Differentiation during the Immune Response to Invasive Pulmonary Aspergillosis.

Background:Triggering receptor expressed on myeloid cell-1 (TREM-1) may play a vital role in mammalian target of rapamycin (mTOR) modulation of CD8+ T-cell differentiation through the transcription factors T-box expressed in T-cells and eomesodermin during the immune response to invasive pulmonary aspergillosis (IPA). This study aimed to investigate whether the mTOR signaling pathway modulates the proliferation and differentiation of CD8+ T-cells during the immune response to IPA and the role TREM-1 plays in this process.Methods:Cyclophosphamide (CTX) was injected intraperitoneally, and Aspergillus fumigatus spore suspension was inoculated intranasally to establish the immunosuppressed IPA mouse model. After inoculation, rapamycin (2 mg·kg−1·d−1) or interleukin (IL)-12 (5 μg/kg every other day) was given for 7 days. The number of CD8+ effector memory T-cells (Tem), expression of interferon (IFN)-γ, mTOR, and ribosomal protein S6 kinase (S6K), and the levels of IL-6, IL-10, galactomannan (GM), and soluble TREM-1 (sTREM-1) were measured.Results:Viable A. fumigatus was cultured from the lung tissue of the inoculated mice. Histological examination indicated greater inflammation, hemorrhage, and lung tissue injury in both IPA and CTX + IPA mice groups. The expression of mTOR and S6K was significantly increased in the CTX + IPA + IL-12 group compared with the control, IPA (P = 0.01; P = 0.001), and CTX + IPA (P = 0.034; P = 0.032) groups, but significantly decreased in the CTX + IPA + RAPA group (P < 0.001). Compared with the CTX + IPA group, the proportion of Tem, expression of IFN-γ, and the level of sTREM-1 were significantly higher after IL-12 treatment (P = 0.024, P = 0.032, and P = 0.017, respectively), and the opposite results were observed when the mTOR pathway was blocked by rapamycin (P < 0.001). Compared with the CTX + IPA and CTX + IPA + RAPA groups, IL-12 treatment increased IL-6 and downregulated IL-10 as well as GM, which strengthened the immune response to the IPA infection.Conclusions:mTOR modulates CD8+ T-cell differentiation during the immune response to IPA. TREM-1 may play a vital role in signal transduction between mTOR and the downstream immune response.

Posaconazole-Loaded Leukocytes as a Novel Treatment Strategy Targeting Invasive Pulmonary Aspergillosis.

Impaired delivery of antifungals to hyphae within necrotic lesions is thought to contribute to therapeutic failure in invasive pulmonary aspergillosis (IPA). We hypothesized that transfusion of leukocytes loaded ex vivo with the lipophilic antifungal posaconazole could improve delivery of antifungals to the sites of established infection and improve outcome in experimental IPA. The HL-60 leukemia cell line was differentiated to a neutrophil-like phenotype (differentiated HL-60 [dHL-60] cells) and then exposed to a range of posaconazole concentrations. The functional capacity and antifungal activity of these cells were assessed in vitro and in a mouse model of IPA. Posaconazole levels in dHL-60 cells were 265-fold greater than the exposure concentration. Posaconazole-loaded cells were viable and maintained their capacity to undergo active chemotaxis. Contact-dependent transfer of posaconazole from dHL-60 cells to hyphae was observed in vitro, resulting in decreased fungal viability. In a neutropenic mouse model of IPA, treatment with posaconazole-loaded dHL-60 cells resulted in significantly reduced fungal burden in comparison to treatment with dHL-60 cells alone. Posaconazole accumulates at high concentrations in dHL-60 cells and increases their antifungal activity in vitro and in vivo. These findings suggest that posaconazole-loading of leukocytes may hold promise for the therapy of IPA.

Interleukin‐12 and interleukin‐2 alone or in combination against the infection in invasive pulmonary aspergillosis mouse model

Aspergillus fumigatus is an intracellular opportunistic fungus causing invasive pulmonary mycosis, characterised by hyphal invasion and destruction of pulmonary tissue. Th1 cytokines could enhance fungicidal activity. The effects from the combination of interleukin-12 (IL-12) and IL-2 are rarely known in invasive pulmonary aspergillosis infection. To assess the cleaning of A. fumigatus infection in the pulmonary tissues by IL-12 and IL-2, interferon-γ (IFN-γ) was detected in the sera using ELISA, quantification of IFN-γ mRNA using real-time RT-PCR and lung Colony-forming unit was assayed by cultivation. Morphology was analysed by histopathological examination. Our results showed that IL-12 and/or IL-2 could enhance the IFN-γ expression in the pulmonary tissue, reduce the colony load in the pulmonary tissue and increase the survival rate of mouse. The combination of IL-12 and IL-2 could assist in increasing the IFN-γ expression in the pulmonary tissue, but neither reduce colony load in the pulmonary tissue nor increase the survival rate of mouse significantly. It was demonstrated that IL-12 and IL-2 were strong immunomodulatory cytokines as a prerequisite for protecting the host from infectious agents.