Jonathan P. Wong

Liposome delivery of ciprofloxacin against intracellular Francisella tularensis infection

The effect of liposome delivery on the controlled release and therapeutic efficacy of ciprofloxacin against intracellular Francisella tularensis infection in vivo was evaluated in this study. Ciprofloxacin was encapsulated in small unilamellar vesicles by a remote loading procedure using an ammonium sulfate gradient. This procedure produced uniform sized liposomes (100 nm) with an entrapment rate of 90+/-3.5%. Following administration of unencapsulated or liposome-encapsulated ciprofloxacin by intravenous injection or aerosol inhalation, levels of ciprofloxacin in sera, lungs, liver and spleen were determined using 14C-ciprofloxacin as radiotracer for ciprofloxacin. Intravenous injection of liposome-encapsulated ciprofloxacin resulted in higher serum levels of drug in serum, as well as increased drug retention in lungs, liver and spleen, compared to that of free encapsulated drug. Aerosol administration of liposome-encapsulated ciprofloxacin by jet nebulization resulted in significantly higher drug levels and prolonged drug retention in the lower respiratory tract compared to the free drug. Aerosol inhalation of liposome-encapsulated ciprofloxacin, given either prophylactically or therapeutically, provided complete protection to mice against a pulmonary lethal infection model of F. tularensis. In contrast, ciprofloxacin given in its free form, was ineffective. These results suggest that liposome encapsulation of ciprofloxacin enhances drug delivery to the primary site of infection and results in increasing therapeutic efficacy against F. tularensis.

Activation of toll-like receptor signaling pathway for protection against influenza virus infection.

Abstract This study aims to evaluate the antiviral role of nucleic acid-based agonists for the activation of toll-like receptor (TLR) signaling pathways, and its protective role in respiratory influenza A virus infections. TLR-3 is expressed on myeloid dendritic cells, respiratory epithelium, and macrophages, and appears to play a central role in mediating both the antiviral and inflammatory responses of the innate immunity in combating viral infections. Influenza viruses can effectively inhibit the hosts ability to produce interferons, and thereby suppress the immune systems antiviral defence mechanisms. Poly ICLC is a synthetic double stranded RNA comprising of polyriboinosinic-poly ribocytidylic acid (Poly IC) stabilized with l-lysine (L) and carboxymethylcellulose (C). Poly ICLC and liposome-encapsulated Poly ICLC (LE Poly ICLC) are TLR-3 agonists and are potent inducer of interferons and natural killer cells. Intranasal pre-treatment of mice with Poly ICLC and LE Poly ICLC provided high level of protection against lethal challenge with a highly lethal avian H5N1 influenza (HPAI) strain (A/H5N1/chicken/Henan clade 2), and against lethal seasonal influenza A/PR/8/34 [H1N1] and A/Aichi/2 [H3N2] virus strains. The duration of protective antiviral immunity to multiple lethal doses of influenza virus A/PR/8/34 virus had been previously found to persist for up to 3 weeks in mice for LE Poly ICLC and 2 weeks for Poly ICLC. Similarly, pre-treatment of mice with CpG oligonucleotides (TLR-9 agonist) was also found to provide complete protection against influenza A/PR/8/34 infection in mice. RT-PCR analysis of lung tissues of mice treated with Poly ICLC and LE Poly ICLC revealed upregulation of TLR-3 mRNAs gene expression. Taken together, these results do support the potential role of TLR-3 and TLR-9 agonists such as Poly ICLC and LE Poly ICLC in protection against lethal seasonal and HPAI virus infection.

Prophylactic and therapeutic efficacies of poly(IC.LC) against respiratory influenza A virus infection in mice.

Polyriboinosinic-polyribocytidylic acid [poly(IC.LC)] was evaluated for its prophylactic and therapeutic efficacies against respiratory influenza A virus infection in mice. Two doses of poly(IC.LC) (1 mg/kg of body weight per dose) administered intranasally within 12 days prior to infection with 10 50% lethal doses of mouse-adapted influenza A/PR/8 virus fully protected the mice against the infection. Determination of virus titers by hemagglutination and plaque assays showed more than a 2-log10 decrease in virus titers in lung homogenates of pretreated mice compared with those in the lungs of the nonpretreated group. Treatment of infected mice with poly(IC.LC) resulted in a modest (40%) survival rate. These results suggest that poly(IC.LC) provides a highly effective prophylaxis against respiratory influenza A virus infection in mice.

Therapeutic efficacy of Nubiotics against burn wound infection by Pseudomonas aeruginosa

ABSTRACT “Nubiotics” are a novel class of proprietary protonated nucleic acid-based drugs shown to have potent in vitro antibacterial activities against a number of gram-positive and gram-negative bacteria. These nubiotics are evaluated here for their in vivo therapeutic efficacy for the treatment of burn wound infection caused by Pseudomonas aeruginosa. To achieve this, a burn wound infection model was established in mice by using a highly pathogenic burn wound clinical isolate of P. aeruginosa. Lethal doses of the bacteria were determined for two routes of infection (subcutaneous and topical), representing systemic and local forms of infection, respectively. Using this infection model, treatment with nubiotics by various routes of drug administration was evaluated and optimized. A total of 12 nubiotics and their analogues were tested and of these, Nu-2, -3, -4, and -5 were found to be extremely efficacious in the postexposure treatment of burn wound infection (60 to 100% survival rates versus 0% for untreated control [P < 0.05]). These nubiotics were effective when given either systemically by intravenous and/or subcutaneous administration or given locally to the affected site in the skin by topical application. Treatment by these two routes resulted in almost 100% survival rates and complete eradication of the bacteria from infection sites in the livers, spleens, and blood. These nubiotics were found to be as effective as intravenously administered ciprofloxacin, a potent and broad-spectrum fluoroquinolone. These results suggest that nubiotics may be a promising and effective approach for the treatment of burn wound infection caused by P. aeruginosa.

Liposome-mediated immunotherapy against respiratory influenza virus infection using double-stranded RNA poly ICLC

The use of liposome delivery technology to enhance the antiviral activity of poly ICLC (an immunomodulating dsRNA) while decreasing its intrinsic toxicity is evaluated in this study. The antiviral efficacies of free and liposome-encapsulated poly ICLC were evaluated and compared using a lethal respiratory influenza A virus infection in mice. The toxicity profiles of free and liposome-encapsulated poly ICLC were compared by determining the extent of hypothermia and loss in body weights in mice pretreated with these drugs. Poly ICLC was encapsulated in cationic liposomes prepared by the freeze drying method. To determine the antiviral efficacies of free and liposome-encapsulated poly ICLC, mice were intranasally pretreated with two doses of poly ICLC (free or liposomal, 1 mg/kg/dose) given 48 h apart. At various times post pretreatment, mice were intranasally challenged with 10 LD50 mouse-adapted influenza A/PR/8 (H1N1) virus. The survival rates of the mice were determined at day 14 post infected and compared to the untreated control mice. Results indicate mice pretreated with liposome-encapsulated poly ICLC within 3 weeks prior to virus challenge were completely protected (100% survival compared to 0% for the untreated control group, p < 0.001), while window of protection provided by free unencapsulated poly ICLC was 12 days. When the toxicity profiles of free and liposome-encapsulated poly ICLC were compared, it was found that hypothermia and body weight loss induced by poly ICLC were either completely mitigated or significantly reduced in mice given equivalent doses of poly ICLC in the liposome-encapsulated form. These results suggest that liposomes are an excellent drug carrier for poly ICLC, that liposome-encapsulated poly ICLC may provide a safe and effective immunotherapeutic approach for the prevention of respiratory influenza virus infections.

DNA vaccination against respiratory influenza virus infection.

DNA vaccination using plasmid encoding the hemagglutinin (HA) gene of influenza A/PR/8/34 virus to induce long-lasting protective immunity against respiratory infection was evaluated in this study. Using liposomes as carriers, the efficacy of DNA vaccines was determined using a lethal influenza infection model in mice. Mice immunized intranasally or intramuscularly with liposome-encapsulated pCI plasmid encoding HA (pCI-HA10) were completely protected against an intranasal 5 LD(50) influenza virus challenge. Mice immunized with liposome-encapsulated pCI-HA10, but not naked pCI-HA10, by intranasal administration were found to produce high titers of serum IgA. These results suggest DNA vaccines encapsulated in liposomes are efficacious in inducing complete protective immunity against respiratory influenza virus infection.

The potential of liposome–encapsulated ciprofloxacin as a tularemia therapy

Liposome-encapsulation has been suggested as method to improve the efficacy of ciprofloxacin against the intracellular pathogen, Francisella tularensis. Early work with a prototype formulation, evaluated for use against the F. tularensis live vaccine strain, showed that a single dose of liposomal ciprofloxacin given by the intranasal or inhalational route could provide protection in a mouse model of pneumonic tularemia. Liposomal ciprofloxacin offered better protection than ciprofloxacin given by the same routes. Liposomal ciprofloxacin has been further developed by Aradigm Corporation for Pseudomonas aeruginosa infections in patients with cystic fibrosis and non-cystic fibrosis bronchiectasis. This advanced development formulation is safe, effective and well tolerated in human clinical trials. Further evaluation of the advanced liposomal ciprofloxacin formulation against the highly virulent F. tularensis Schu S4 strain has shown that aerosolized CFI (Ciprofloxacin encapsulated in liposomes for inhalation) provides significantly better protection than oral ciprofloxacin. Thus, liposomal ciprofloxacin is a promising treatment for tularemia and further research with the aim of enabling licensure under the animal rule is warranted.

Immunoprophylactic strategies against respiratory influenza virus infection

The objective of this report is to evaluate the prophylactic efficacy of liposome-mediated immunotherapy for prevention of respiratory influenza virus infection in mice. Antiviral antibody, interferon-gamma and poly (ICLC) were encapsulated in liposomes and they were evaluated for their ability to induce protective immunity against lethal influenza infection. Passive immunization using liposome-encapsulated antiviral antibody was found to offer complete protection against the virus challenge. However, this pretreatment must be administered within 24 h prior to virus challenge to be protective. Pretreatment with liposome-encapsulated interferon-gamma was found to stimulate cellular immune responses, but the protection is partial. Immunoprophylaxis using liposome-encapsulated double-stranded (ds) RNA poly (ICLC) provided complete and longer-lasting protection against influenza infection. These results suggest liposome-mediated immunoprophylactic approaches are effective in the prevention of respiratory influenza virus infection.

Prophylactic, therapeutic and immune enhancement effect of liposome-encapsulated PolyICLC on highly pathogenic H5N1 influenza infection

In view of the magnitude and severity of outbreaks of the highly pathogenic H5N1 influenza virus (H5N1‐HPIV) and the threat to public health, there is an urgent need to develop broad‐spectrum prophylactic and therapeutic agents against infection by H5N1‐HPIV and other subtypes.

Regulatory roles of c-jun in H5N1 influenza virus replication and host inflammation

The cytokine storm which is a great burden on humanity in highly pathogenic influenza virus infections requires activation of multiple signaling pathways. These pathways, such as MAPK and JNK, are important for viral replication and host inflammatory response. Here we examined the roles of JNK downstream molecule c-jun in host inflammatory responses and H5N1 virus replication using a c-jun targeted DNAzyme (Dz13). Transfection of Dz13 significantly reduced H5N1 influenza virus replication in human lung epithelial cells. Concomitantly, there was a decreased expression of pro-inflammatory cytokines (tumor necrosis factor (TNF)-α, interferon (IFN)-β and interleukin (IL)-6) in c-jun suppressed cells, while the expression of anti-inflammatory cytokines, such as IL-10, was increased. In vivo, compared with control groups, suppression of c-jun improved the survival rate of mice infected with H5N1 virus (55.5% in Dz13 treated mice versus ≤11% of control mice) and decreased the CD8(+) T cell proliferation. Simultaneously, the pulmonary inflammatory response and viral burden also decreased in the Dz13 treated group. Thus, our data demonstrated a critical role for c-jun in the establishment of H5N1 infection and subsequent inflammatory reactions, which suggest that c-jun may be a potential therapeutic target for viral pneumonia.