Dendrimer-based posaconazole nanoplatform for antifungal therapy.

We examined formulating a new antifungal agent, posaconazole (POS) and its derivatives, with different molecular vehicles. Several combinations of drug and carrier molecules were synthesized, and their antifungal activities were evaluated against Aspergillus fumigatus. Posaconazole and four of its derivatives were conjugated to either generation 5 (G5) dendrimers or partially modified G5 dendrimers. The in vitro antifungal activities of these compounds suggest that conjugates with specific chemical linkages showed better fungistatic activity than direct conjugates to POS. In particular, a polyethylene glycol (PEG)-imidazole modified G5 dendrimer demonstrated improved antifungal efficacy relative to the parent G5 molecule. Further studies were then conducted with POS derived molecules coupled to PEG-imidazole modified G5 dendrimers to achieve a highly soluble and active conjugate of POS. This conjugated macromolecule averaged 23 POS molecules per G5 and had a high solubility with 50 mg/mL, which improved the molar solubility of POS from less than 0.03 mg/mL to as high as 16 mg/mL in water. The primary release profile of the drug in human plasma was extended to over 72 h, which is reflected in the in vitro inhibition of A. fumigatus growth of over 96 h. These POS-polymer conjugates appear to be novel and efficient antifungal agents.

Nanoemulsion is an effective antimicrobial for methicillin-resistant Staphylococcus aureus in infected wounds.

AIM: To develop NB-201, a nanoemulsion compound, as a novel microbicidal agent against methicillin-resistant Staphylococcus aureus (MRSA) infection, which is a common threat to public health but with limited therapeutic options. MATERIALS & METHODS: NB-201 was tested in in vitro and in vivo murine and porcine models infected with MRSA. RESULTS: Topical treatment of MRSA-infected wounds with NB-201 significantly decreased bacterial load and had no toxic effects on healthy skin tissues. NB-201 attenuated neutrophil sequestration in MRSA-infected wounds and inhibited epidermal and deep dermal inflammation. The levels of proinflammatory cytokines were reduced in NB-201-treated MRSA-infected wounds. CONCLUSION: NB-201 can greatly reduce inflammation characteristic of infected wounds and has antimicrobial activity that effectively kills MRSA regardless of the genetic basis of antibiotic resistance.

Screening of Nanoemulsion Formulations and Identification of NB-201 as an Effective Topical Antimicrobial for Staphylococcus aureus in a Mouse Model of Infected Wounds.

Despite advances in antimicrobial therapies, wound infection remains a global public health concern. We aimed to formulate and assess various nanoemulsions (NEs) for potential effectiveness as stable antimicrobial agents suitable for topic application. A total of 106 NEs were developed that varied with respect to nonionic and cationic surfactants. Stability testing demonstrated that the NEs tested are broadly stable, with 97/106 formulations passing 2-week stability tests. Two NEs, NB-201 and NB-402, were selected to test antimicrobial activity in a wound model in mice. Skin abrasion wounds were infected with Staphylococcus aureus followed by NE treatment. Infected skin was then evaluated by measuring colony forming units. NB-201 reduced median bacterial counts by 4 to 5 log compared to animals treated with saline, whereas NB-402 reduced bacterial counts by 2 to 3 log. Additional stability tests on NB-201 demonstrated that NB-201 is stable in the presence of human serum, and is stable for at least 6 months at 5°C, 25°C, and 40°C. Finally, in in vitro studies, NB-201 was found to be effective against S. aureus at a higher dilution than the commercially available silver sulfadiazine. Altogether these results demonstrate that NB-201 is a stable and effective topical antimicrobial for the treatment of S. aureus.

Senescence: novel insight into DLX3 mutations leading to enhanced bone formation in Tricho-Dento-Osseous syndrome.

The homeodomain transcription factor distal-less homeobox 3 gene (DLX3) is required for hair, tooth and skeletal development. DLX3 mutations have been found to be responsible for Tricho-Dento-Osseous (TDO) syndrome, characterized by kinky hair, thin-pitted enamel and increased bone density. Here we show that the DLX3 mutation (c.533 A>G; Q178R) attenuates osteogenic potential and senescence of bone mesenchymal stem cells (BMSCs) isolated from a TDO patient, providing a molecular explanation for abnormal increased bone density. Both DLX3 mutations (c.533 A>G and c.571_574delGGGG) delayed cellular senescence when they were introduced into pre-osteoblastic cells MC3T3-E1. Furthermore, the attenuated skeletal aging and bone loss in DLX3 (Q178R) transgenic mice not only reconfirmed that DLX3 mutation (Q178R) delayed cellular senescence, but also prevented aging-mediated bone loss. Taken together, these results indicate that DLX3 mutations act as a loss of function in senescence. The delayed senescence of BMSCs leads to increased bone formation by compensating decreased osteogenic potentials with more generations and extended functional lifespan. Our findings in the rare human genetic disease unravel a novel mechanism of DLX3 involving the senescence regulation of bone formation.

Prevention of influenza pneumonitis by sialic Acid-conjugated dendritic polymers.

Influenza A viral infection begins by hemagglutinin glycoproteins on the viral envelope binding to cell membrane sialic acid (SA). Free SA monomers cannot block hemagglutinin adhesion in vivo because of toxicity. Polyvalent, generation 4 (G4) SA-conjugated polyamidoamine (PAMAM) dendrimer (G4-SA) was evaluated as a means of preventing adhesion of 3 influenza A subtypes (H1N1, H2N2, and H3N2). In hemagglutination-inhibition assays, G4-SA was found to inhibit all H3N2 and 3 of 5 H1N1 influenza subtype strains at concentrations 32-170 times lower than those of SA monomers. In contrast, G4-SA had no ability to inhibit hemagglutination with H2N2 subtypes or 2 of 5 H1N1 subtype strains. In vivo experiments showed that G4-SA completely prevented infection by a H3N2 subtype in a murine influenza pneumonitis model but was not effective in preventing pneumonitis caused by an H2N2 subtype. Polyvalent binding inhibitors have potential as antiviral therapeutics, but issues related to strain specificity must be resolved.