Most licensed seasonal influenza vaccines are non-adjuvanted and rely primarily on vaccine-induced antibody titers for protection. As such, seasonal antigenic drift and suboptimal vaccine strain selection often results in reduced vaccine efficacy. Further, seasonal H3N2 influenza vaccines demonstrate poor efficacy compared to H1N1 and influenza type B vaccines. New vaccines, adjuvants, or delivery technologies that can induce broader or cross-seasonal protection against drifted influenza virus strains, likely through induction of protective T cell responses, are urgently needed. Here, we report novel lipidated TLR7/8 ligands that act as strong adjuvants to promote influenza-virus specific Th1-and Th17-polarized T cell responses and humoral responses in mice with no observable toxicity. Further, the adjuvanted influenza vaccine provided protection against a heterologous H3N2 influenza challenge in mice. These responses were further enhanced when combined with a synthetic TLR4 ligand adjuvant. Despite differences between human and mouse TLR7/8, these novel lipidated imidazoquinolines induced the production of cytokines required to polarize a Th1 and Th17 immune response in human PBMCs providing additional support for further development of these compounds as novel adjuvants for the induction of broad supra-seasonal protection from influenza virus.

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Gonadotropin-releasing hormone (GnRH) stimulates the synthesis and secretion of the gonadotropins that maintain the reproductive axis in mammals. Efforts have focused on the characterization of novel, nonpeptidic orally active antagonists of the GnRH receptor. An erythromycin A derivative, A-198401 (11-deoxy-11-[carboxy (3,4-,12-(cyclic carbamate), showed nanomolar affinity for the human (CHO-21) and rat GnRH receptors in vitro (pK values 8.7 ± 0.2 and 9.2 ± 0.14, respectively). In a functional in vitro assay, A-198401 inhibited leuprolide-induced release of luteinizing hormone (LH) from cultured rat pituitary cells with a pA 2 value of 8.8. Intravenous (IV) dosing of A-198401 in castrate male rats produced a significant dose-dependent suppression of LH production with an ED 80 value of 5.26 mg/kg. Sustained testosterone (T) suppression was observed after IV dosing of A-198401 in the intact rat, with a 10-mg/kg-dose producing 9-24 h suppression. Analysis of the IV and PO data indicate that A-198401 has a bioavailability of 15%. A-198401 is a novel nonpeptide GnRH antagonist that produces significant and sustained suppression of LH and T production in animal models when dosed either IV or PO and may provide the basis for a therapeutic GnRH antagonist for the clinical treatment of reproductive hormone-dependent diseases. Drug Dev. Res. 52:485-491, 2001.

Toll-like receptors 7 and 8 (TLR7/8) are broadly expressed on antigen-presenting cells, making TLR7/8 agonists likely candidates for the development of new vaccine adjuvants. We previously reported the synthesis of a new series of 8-oxoadenines substituted at the 9-position with a 4-piperidinylalkyl moiety and demonstrated that TLR7/8 selectivity and potency could be modulated by varying the length of the alkyl linker. In the present study, we broadened our initial structure–activity relationship study to further evaluate the effects of N-heterocycle ring size, chirality, and substitution on TLR7/8 potency, receptor selectivity, and cytokine (IFNα and TNFα) induction from human peripheral blood mononuclear cells (PBMCs). TLR7/8 activity correlated primarily to linker length and to a lesser extent to ring size, while ring chirality had little effect on TLR7/8 potency or selectivity. Substitution of the heterocyclic ring with an aminoalkyl or hydroxyalkyl group for subsequent conjugation to phospholipids or antigens was well tolerated with the retention of both TLR7/8 activity and cytokine induction from human PBMCs.

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