Three ellipticine-estradiol conjugates were synthesized in an effort to target the cytotoxicity of ellipticine to estrogen-receptor positive cells. The three conjugates were prepared with linker chains extending from the 17 alpha position of the estradiol to N-2 (compound 3), N-6 (compound 4), and C-9 (compound 5) positions of ellipticine. The ellipticine-estradiol conjugates were evaluated for their abilities to bind to estrogen receptors, to inhibit topoisomerase II, and for their cytotoxicities in human cancer cell lines. Conjugates 3 and 5 displayed weak binding affinities of 0.132 and 0.303 for the estrogen receptor (relative to estradiol = 100), while conjugate 4 did not show any detectable binding to the estrogen receptor. Compound 3 was a moderate inhibitor of topoisomerase II (IC50 24.1 microM), while 4 and 5 were inactive. Conjugate 3 was consistently more cytotoxic (GI50 values 1-10 microM) than compounds 4 and 5 (GI50 values 10-100 microM) in a variety of human cancer cell lines. None of the compounds displayed any selectivity for estrogen-receptor positive cell lines, which probably reflects their weak affinities for estrogen receptors.

The in vivo efficacy of JNJ-Q2, a new broad-spectrum fluoroquinolone (FQ), was evaluated in a murine septicemia model with methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) and in a Streptococcus pneumoniae lower respiratory tract infection model. JNJ-Q2 and comparators were also evaluated in an acute murine skin infection model using a community-acquired MRSA strain and in an established skin infection (ESI) model using a hospital-acquired strain, for which the selection of resistant mutants was also determined. JNJ-Q2 demonstrated activity in the MSSA septicemia model that was comparable to that moxifloxacin (JNJ-Q2 50% effective dose [ED 50 Successive improvements in the spectrum and antimicrobial potency of agents in the fluoroquinolone class have resulted in widespread clinical utility of these agents, and the activities of levofloxacin and moxifloxacin against Gram-positive pathogens, particularly Streptococcus pneumoniae, have contributed to the adoption of these agents for the empirical treatment of respiratory tract infections in the community setting. Although fluoroquinolone resistance in S. pneumoniae remains low, with the rate of levofloxacin resistance in U.S. isolates typically reported at less than 1% (12), the rate of fluoroquinolone resistance has, in selected populations or geographic regions, been reported to be greater than 10% (1). In association with the introduction of the seven-valent pneumococcal vaccine (PCV7), an increased prevalence in non-PCV7 serotypes has been observed (11, 12), including several predominant fluoroquinolone-resistant and multidrug-resistant clones (4, 10). Several of the marketed fluoroquinolone agents also display in vitro activity against Staphylococcus aureus isolates and have been used successfully to treat staphylococcal infections (31), although none of these marketed agents are approved for the treatment of methicillin-resistant S. aureus (MRSA) infections. MRSA has become an increasingly important pathogen in community infections (19), and the increased incidence of infection is associated with elevated resistance, with levofloxacin resistance observed in 70% of recent U.S. clinical MRSA isolates (18). Community staphylococcal isolates typically express elevated levels of several virulence determinants, which are associated with increased virulence in murine models of bacteremia and skin abscess infection (20). Efficacy in murine models of MRSA infection is a key attribute for new antibacterial agents targeted for the treatment of staphylococcal infections, including MRSA infections in the community setting. Several investigational fluoroquinolones active against MRSA (2,5,15,17,32) are reported to be the subject of ongoing clinical studies that are investigating their efficacy in the treatment of acute bacterial skin and skin structure infections (ABSSSI) caused by MRSA. The development of new fluoroquinolone agents retaining activity against multidrug-resistant S. pneumoniae isolates and displaying potent a...

BackgroundGroup B Neisseria meningitidis, an endotoxin-producing Gram-negative bacterium, causes the highest incidence of group B meningococcus (MenB) disease in the first year of life. The Bexsero vaccine is indicated in Europe from 8 weeks of age. Endotoxin components of outer membrane vesicles (OMVs) or soluble lipopolysaccharide (LPS) represent a potential source of inflammation and residual reactogenicity. The purpose of this study was to compare novel candidate MenB vaccine formulations with licensed vaccines, including Bexsero, using age-specific human in vitro culture systems.MethodsOMVs from wild type- and inactivated lpxL1 gene mutant-N. meningitidis strains were characterized in human neonatal and adult in vitro whole blood assays and dendritic cell (DC) arrays. OMVs were benchmarked against licensed vaccines, including Bexsero and whole cell pertussis formulations, with respect to Th-polarizing cytokine and prostaglandin E2 production, as well as cell surface activation markers (HLA-DR, CD86, and CCR7). OMV immunogenicity was assessed in mice.ResultsΔlpxLI native OMVs (nOMVs) demonstrated significantly less cytokine induction in human blood and DCs than Bexsero and most of the other pediatric vaccines (e.g., PedvaxHib, EasyFive, and bacillus Calmette–Guérin) tested. Despite a much lower inflammatory profile in vitro than Bexsero, ΔlpxLI nOMVs still had moderate DC maturing ability and induced robust anti-N. meningitidis antibody responses after murine immunization.ConclusionA meningococcal vaccine comprised of attenuated LPS-based OMVs with a limited inflammatory profile in vitro induces robust antigen-specific immunogenicity in vivo.

A key aspect underlying the severity of infections caused by Staphylococcus aureus is the abundance of virulence factors that the pathogen uses to thwart critical components of the human immune response. One such mechanism involves the destruction of host immune cells by cytolytic toxins secreted by S. aureus, including five bicomponent leukocidins: PVL, HlgAB, HlgCB, LukED, and LukAB. Purified leukocidins can lyse immune cells ex vivo, and systemic injections of purified LukED or HlgAB can acutely kill mice. Here, we describe the generation and characterization of centyrins that bind S. aureus leukocidins with high affinity and protect primary human immune cells from toxin-mediated cytolysis. Centyrins are small protein scaffolds derived from the fibronectin type III–binding domain of the human protein tenascin-C. Although centyrins are potent in tissue culture assays, their short serum half-lives limit their efficacies in vivo. By extending the serum half-lives of centyrins through their fusion to an albumin-binding consensus domain, we demonstrate the in vivo efficacy of these biologics in a murine intoxication model and in models of both prophylactic and therapeutic treatment of live S. aureus systemic infections. These biologics that target S. aureus virulence factors have potential for treating and preventing serious staphylococcal infections.