New vaccines needed for pathogens infecting animals and humans: One Health.

The field of "One Health" encourages researchers to collaborate across a wide range of disciplines to improve health at the animal-human-ecosystems interface. One Health recognizes the potential of emerging infectious diseases to impact public health and global food security, and the need for a multidisciplinary approach to counteract the effect of these diseases. Vaccinologists are also beginning to engage in research related to One Health, recognizing that preventing transmission of emerging infectious diseases at the animal-human interface is critically important for protecting the world population from epizootics and pandemics. In this synopsis of recent work in the One Health field, we describe some emerging One Health pathogens, discuss the importance of One Health to food safety and biodefense, propose strategies for improving One Health including the development of new vaccines and new vaccine design approaches, and close with a brief discussion of the opportunities and risks related to One Health vaccine research.

Identification of a novel class of succinyl-nitrile-based Cathepsin S inhibitors.

The synthesis and in vitro activities of a series of succinyl-nitrile-based inhibitors of Cathepsin S are described. Several members of this class show nanomolar inhibition of the target enzyme as well as cellular potency. The inhibitors displaying the greatest potency contain N-alkyl substituted piperidine and pyrrolidine rings spiro-fused to the alpha-carbon of the P1 residue.

Discovery of potent and selective PKC-theta inhibitors.

An uHTS campaign was performed to identify selective inhibitors of PKC-theta. Initial triaging of the hit set based on selectivity and historical analysis led to the identification of 2,4-diamino-5-nitropyrimidines as potent and selective PKC-theta inhibitors. A homology model and initial SAR is presented demonstrating that a 2-arylalkylamino substituent in conjunction with suitable 4-diamino substituent are essential for achieving selectivity over many kinases. Additional hit to lead profiling is presented on selected compounds.

An orally active reversible inhibitor of cathepsin S inhibits human trans vivo delayed-type hypersensitivity.

Cathepsin S is a major histocompatibility complex (MHC) class II associated invariant chain (Ii) degrading enzyme expressed in antigen presenting cells such as B cells and dendritic cells. This enzyme is essential for MHC class II associated antigen processing and presentation to CD4(+) T cells. Compound I, a selective, reversible and orally bioavailable, inhibitor of cathepsin S, with molecular IC(50)=9 nM, has been recently described. We have tested the effects of compound I in a trans vivo model of delayed-type hypersensitivity. Human peripheral blood mononuclear cells (7-10 x 10(6)) from tetanus-sensitized donors were co-injected with tetanus toxoid (0.25 Lf) into C57Bl/6 mouse footpads. At 24 h, significant footpad swelling (+0.024+/-0.001 cm) characterized by an influx of mouse neutrophils and monocytes was observed. Injection of peripheral blood mononuclear cells alone caused negligible swelling (0.002+/-0.0002 cm). Anti-human MHC class II (HLA-DR, DP, DQ) antibody (5 mg/kg, i.p.) inhibited the swelling 91+/-7%, thus demonstrating a role of human antigen presenting cells in this model. Compound I (10, 30, and 100 mg/kg, p.o.) inhibited the response with an ED50 of approximately 18 mg/kg. Compound III, a less active analogue (molecular IC50>20 microM) had no effect. Furthermore, pretreatment of peripheral blood mononuclear cells with 10 nM compound II, an irreversible inhibitor (molecular IC50=11 nM) inhibited swelling 87+/-4%. These findings support the role of cathepsin S in human delayed-type hypersensitivity. Inhibition of cathepsin S with compound I may be useful in the treatment of human autoimmune diseases like rheumatoid arthritis and multiple sclerosis.

Cysteine protease cathepsin S as a key step in antigen presentation.

Cathepsin S is a cysteine protease in the papain super-family. Studies have shown that it is highly expressed in antigen-presenting cells. Along with other lysosomal proteases, cathepsin S plays an important role in the major histocompatibility complex class II-restricted antigen presentation, especially in the degradation of the invariant chain, a chaperone peptide bound to the class II complex. Compared with other lysosomal cysteine proteases, cathepsin S has displayed some unique characteristics. As a result, cathepsin S has been implicated as a potential target in the treatment of various disorders ranging from autoimmune diseases to atherosclerosis. Furthermore, a number of small-molecule cathepsin S inhibitors have demonstrated efficacy in disease-relevant models.

The design of potent hydrazones and disulfides as cathepsin S inhibitors.

The design and synthesis of dipeptidyl disulfides and dipeptidyl benzoylhydrazones as selective inhibitors of the cysteine protease Cathepsin S are described. These inhibitors were expected to form a slowly reversible covalent adduct of the active site cysteine of Cathepsin S. Formation of the initial adduct was confirmed by mass spectral analysis. The nature and mechanism of these adducts was explored. Kinetic analysis of the benzoyl hydrazones indicate that these inhibitors are acting as irreversible inhibitors of Cathepsin S. Additionally, the benzoylhydrazones were shown to be potent inhibitors of Cathepsin S processing of Class II associated invariant peptide both in vitro and in vivo.

Design and synthesis of dipeptide nitriles as reversible and potent Cathepsin S inhibitors.

The specificity of the immune response relies on processing of foreign proteins and presentation of antigenic peptides at the cell surface. Inhibition of antigen presentation, and the subsequent activation of T-cells, should, in theory, modulate the immune response. The cysteine protease Cathepsin S performs a fundamental step in antigen presentation and therefore represents an attractive target for inhibition. Herein, we report a series of potent and reversible Cathepsin S inhibitors based on dipeptide nitriles. These inhibitors show nanomolar inhibition of the target enzyme as well as cellular potency in a human B cell line. The first X-ray crystal structure of a reversible inhibitor cocrystallized with Cathepsin S is also reported.

Enantioselective Synthesis of alpha,alpha-Disubstituted Amino Acid Derivatives via Enzymatic Resolution: Preparation of a Thiazolyl-Substituted alpha-Methyl alpha-Benzyl Amine.

A new and efficient enantioselective synthesis of the (S)-alpha,alpha-disubstituted phenethylamine 1 via Lipase resolution of the esters 3 and 4 is described. The effect of pH, enzyme load, and solubilizing additives has been studied and optimized. Conversion of the carboxylic acid 10 to the desired thiazole 1 is accomplished in high overall yield via an intermediate oxazolinone 13. This facile process requires only a single chromatographic step, and multigram quantities of 1 have been prepared.