Advanced Chemical and Imaging Methods for Studying Structure Morphology and Excipients Solid State Transformations in Pharmaceutical Multiparticulate Formulations.

The formulation of paediatric medicines faces significant challenges to meet the requirements for safe and accurate administration, while maintaining a suitable taste. Multiparticulate formulations have a strong potential to address these challenges because they combine dose flexibility with ease of administration. Understanding the stability of multiparticulate formulations over storage as a function of time and environmental parameters, such as humidity and temperature, is important to manage their commercialisation and use.

Glutamine metabolism inhibition has dual immunomodulatory and antibacterial activities against Mycobacterium tuberculosis.

As one of the most successful human pathogens, Mycobacterium tuberculosis (Mtb) has evolved a diverse array of determinants to subvert host immunity and alter host metabolic patterns. However, the mechanisms of pathogen interference with host metabolism remain poorly understood. Here we show that a glutamine metabolism antagonist, JHU083, inhibits Mtb proliferation in vitro and in vivo.

Glutamine metabolism inhibition has dual immunomodulatory and antibacterial activities against .

As one of the most successful human pathogens, () has evolved a diverse array of determinants to subvert host immunity and alter host metabolic patterns. However, the mechanisms of pathogen interference with host metabolism remain poorly understood. Here we show that a novel glutamine metabolism antagonist, JHU083, inhibits proliferation in vitro and in vivo.

In vivo interferon-gamma induced changes in gene expression dramatically alter neutrophil phenotype.

The cytokine Interferon-γ (IFN-γ) exerts powerful immunoregulatory effects on the adaptive immune system and also enhances functions of the neutrophil (PMN). The clinical use of IFN-γ has been driven by the finding that its administration to patients with chronic granulomatous disease (CGD) results in decreased incidence and severity of infections. However, IFN-γ has no effect on the characteristic defect of CGD, the inability to convert oxygen to microbicidal metabolites including superoxide anion (O2-) during the phagocytosis associated oxidative burst.

Effective Host-Directed Therapy for Tuberculosis by Depletion of Myeloid-Derived Suppressor Cells and Related Cells Using a Diphtheria Toxin Fusion Protein.

Myeloid-derived suppressor cells (MDSCs) are present in elevated numbers in tuberculosis patients and have been found to be permissive for Mycobacterium tuberculosis proliferation. To determine whether depletion of MDSCs may improve host control of tuberculosis, we used a novel diphtheria toxin-based fusion protein DABIL-4 that targets and depletes interleukin 4 (IL-4) receptor-positive cells. We show that DABIL-4 depletes both polymorphonuclear MDSCs and monocytic MDSCs, increases interferon-γ + T cells, and reduces the lung bacillary burden in a mouse tuberculosis model.

Therapeutic targeting with DABIL-4 depletes myeloid suppressor cells in 4T1 triple-negative breast cancer model.

In many solid tumors including triple-negative breast cancer (TNBC), upregulation of the interleukin-4 receptor (IL-4R) has been shown to promote cancer cell proliferation, apoptotic resistance, metastatic potential, and a Th2 response in the tumor microenvironment (TME). Since immunosuppressive cells in the TME and spleen including myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) also express the IL-4R, we hypothesized that selective depletion of IL-4R-bearing cells in TNBC would result in the direct killing of tumor cells and the depletion of immunosuppressive cells and lead to an enhanced antitumor response. To selectively target IL-4R cells, we employed DABIL-4, a fusion protein toxin consisting of the catalytic and translocation domains of diphtheria toxin fused to murine IL-4.

Recent advances with Treg depleting fusion protein toxins for cancer immunotherapy.

T regulatory cells (Tregs) are an important T cell population for immune tolerance, prevention of autoimmune diseases and inhibition of antitumor immunity. The tumor-promoting role played by Tregs in cancer has prompted numerous approaches to develop immunotherapeutics targeting Tregs. One approach to depletion of Treg cells is retargeting the highly potent cytotoxic activity of bacterial toxins.

: Diphtheria Toxin, the Operon, and Its Regulation by Fe2 Activation of apo-DtxR.

Diphtheria is one of the most well studied of all the bacterial infectious diseases. These milestone studies of toxigenic along with its primary virulence determinant, diphtheria toxin, have established the paradigm for the study of other related bacterial protein toxins. This review highlights those studies that have contributed to our current understanding of the structure-function relationships of diphtheria toxin, the molecular mechanism of its entry into the eukaryotic cell cytosol, the regulation of diphtheria expression by holo-DtxR, and the molecular basis of transition metal ion activation of apo-DtxR itself.

Second-generation IL-2 receptor-targeted diphtheria fusion toxin exhibits antitumor activity and synergy with anti-PD-1 in melanoma.

Denileukin diftitox (DAB-IL-2, Ontak) is a diphtheria-toxin-based fusion protein that depletes CD25-positive cells including regulatory T cells and has been approved for the treatment of persistent or recurrent cutaneous T cell lymphoma. However, the clinical use of denileukin diftitox was limited by vascular leak toxicity and production issues related to drug aggregation and purity. We found that a single amino acid substitution (V6A) in a motif associated with vascular leak induction yields a fully active, second-generation biologic, s-DAB-IL-2(V6A), which elicits 50-fold less human umbilical vein endothelial cell monolayer permeation and is 3.

Suppressor Cell-Depleting Immunotherapy With Denileukin Diftitox is an Effective Host-Directed Therapy for Tuberculosis.

Host-directed therapies that augment host immune effector mechanisms may serve as important adjunctive therapies for tuberculosis treatment. We evaluated the activity of denileukin diftitox in an acute mouse model of tuberculosis (TB) infection and analyzed the cellular composition and bacterial burden in lungs and spleens. These in vivo studies show that denileukin diftitox potentiates standard TB treatment in the mouse model, an effect which may be due to depletion of T-regulatory and myeloid-derived suppressor cells during TB infection.

Design and Synthesis of a Pan-Janus Kinase Inhibitor Clinical Candidate (PF-06263276) Suitable for Inhaled and Topical Delivery for the Treatment of Inflammatory Diseases of the Lungs and Skin.

By use of a structure-based computational method for identification of structurally novel Janus kinase (JAK) inhibitors predicted to bind beyond the ATP binding site, a potent series of indazoles was identified as selective pan-JAK inhibitors with a type 1.5 binding mode. Optimization of the series for potency and increased duration of action commensurate with inhaled or topical delivery resulted in potent pan-JAK inhibitor 2 (PF-06263276), which was advanced into clinical studies.

Therapeutic targeting of regulatory T cells enhances tumor-specific CD8+ T cell responses in Epstein-Barr virus associated nasopharyngeal carcinoma.

Epstein-Barr virus (EBV) is associated with multiple malignancies including nasopharyngeal carcinoma (NPC). In nasopharynx cancer, CD8+ T cells specific for EBV Nuclear Antigen-1 (EBNA-1) and Latent Membrane Protein 2 (LMP2) are important components of anti-tumor immunity since both are consistently expressed in NPC. We have previously shown that EBNA-1-specific CD8+ T cell responses were suppressed in NPC patients compared to healthy controls.

Mechanism of diphtheria toxin catalytic domain delivery to the eukaryotic cell cytosol and the cellular factors that directly participate in the process.

Research on diphtheria and anthrax toxins over the past three decades has culminated in a detailed understanding of their structure function relationships (e.g., catalytic (C), transmembrane (T), and receptor binding (R) domains), as well as the identification of their eukaryotic cell surface receptor, an understanding of the molecular events leading to the receptor-mediated internalization of the toxin into an endosomal compartment, and the pH triggered conformational changes required for pore formation in the vesicle membrane.

GRP78(BiP) facilitates the cytosolic delivery of anthrax lethal factor (LF) in vivo and functions as an unfoldase in vitro.

Anthrax toxin is an A/B bacterial protein toxin which is composed of the enzymatically active Lethal Factor (LF) and/or Oedema Factor (EF) bound to Protective Antigen 63 (PA63) which functions as both the receptor binding and transmembrane domains. Once the toxin binds to its cell surface receptors it is internalized into the cell and traffics through Rab5- and Rab7-associated endosomal vesicles. Following acidification of the vesicle lumen, PA63 undergoes a dynamic change forming a beta-barrel that inserts into and forms a pore through the endosomal membrane.

Essential lysine residues within transmembrane helix 1 of diphtheria toxin facilitate COPI binding and catalytic domain entry.

The translocation of the diphtheria toxin catalytic domain from the lumen of early endosomes into the cytosol of eukaryotic cells is an essential step in the intoxication process. We have previously shown that the in vitro translocation of the catalytic domain from the lumen of toxin pre-loaded endosomal vesicles to the external medium requires the addition of cytosolic proteins including coatomer protein complex I (COPI) to the reaction mixture. Further, we have shown that transmembrane helix 1 plays an essential, but as yet undefined role in the entry process.

Effective delivery of antisense peptide nucleic acid oligomers into cells by anthrax protective antigen.

Peptide nucleic acid (PNA) is highly stable and binds to complementary RNA and DNA with high affinity, but it resists cellular uptake, thereby limiting its bioavailability. We investigated whether protectiveantigen (PA, a non-toxic component of anthrax toxin) could transport antisense PNA oligomers into reporter cells that contain luciferase transgenes with mutant beta-globin IVS2 intronic inserts, which permit aberrant pre-mRNA splicing and impair luciferase expression. PNA oligomers antisense to mutant splice sites in these IVS2 inserts induced luciferase expression when effectively delivered into the cells.

Neisseria meningitidis PorB, a Toll-like receptor 2 ligand, improves the capacity of Francisella tularensis lipopolysaccharide to protect mice against experimental tularemia.

Francisella tularensis causes severe pneumonia that can be fatal if it is left untreated. Due to its potential use as a biological weapon, research is being conducted to develop an effective vaccine and to select and study adjuvant molecules able to generate a better and long-lasting protective effect. PorB, a porin from Neisseria meningitidis, is a well-established Toll-like receptor 2 ligand and has been shown to be a promising vaccine adjuvant candidate due to its ability to enhance the T-cell costimulatory activity of antigen-presenting cells both in vitro and in vivo.

COPI coatomer complex proteins facilitate the translocation of anthrax lethal factor across vesicular membranes in vitro.

The delivery of the diphtheria toxin catalytic domain (DTA) from acidified endosomes into the cytoplasm of eukaryotic cells requires protein-protein interactions between the toxin and a cytosolic translocation factor (CTF) complex. A conserved peptide motif, T1, within the DT transmembrane helix 1 mediates these interactions. Because the T1 motif is also present in the N-terminal segments of lethal factor (LF) and edema factor (EF) in anthrax toxin, we asked whether LF entry into the cell might also be facilitated by target cell cytosolic proteins.

Identification of immunologic and pathologic parameters of death versus survival in respiratory tularemia.

Francisella tularensis can cause severe disseminated disease after respiratory infection. The identification of factors involved in mortality or recovery following induction of tularemia in the mouse will improve our understanding of the natural history of this disease and facilitate future evaluation of vaccine candidate preparations. BALB/c mice were infected intranasally with the live vaccine strain (LVS) of F.

A conserved motif in transmembrane helix 1 of diphtheria toxin mediates catalytic domain delivery to the cytosol.

A 10-aa motif in transmembrane helix 1 of diphtheria toxin that is conserved in anthrax edema factor, anthrax lethal factor, and botulinum neurotoxin serotypes A, C, and D was identified by blast, clustal w, and meme computational analysis. Using the diphtheria toxin-related fusion protein toxin DAB(389)IL-2, we demonstrate that introduction of the L221E mutation into a highly conserved residue within this motif results in a nontoxic catalytic domain translocation deficient phenotype. To further probe the function of this motif in the process by which the catalytic domain is delivered from the lumen of early endosomes to the cytosol, we constructed a gene encoding a portion of diphtheria toxin transmembrane helix 1, T1, which carries the motif and is expressed from a CMV promoter.

Both Corynebacterium diphtheriae DtxR(E175K) and Mycobacterium tuberculosis IdeR(D177K) are dominant positive repressors of IdeR-regulated genes in M. tuberculosis.

The diphtheria toxin repressor (DtxR) is an important iron-dependent transcriptional regulator of known virulence genes in Corynebacterium diphtheriae. The mycobacterial iron-dependent repressor (IdeR) is phylogenetically closely related to DtxR, with high amino acid similarity in the DNA binding and metal ion binding site domains. We have previously shown that an iron-insensitive, dominant-positive dtxR(E175K) mutant allele from Corynebacterium diphtheriae can be expressed in Mycobacterium tuberculosis and results in an attenuated phenotype in mice.

Sequence of ligand binding and structure change in the diphtheria toxin repressor upon activation by divalent transition metals.

The diphtheria toxin repressor (DtxR) is an Fe(II)-activated transcriptional regulator of iron homeostatic and virulence genes in Corynebacterium diphtheriae. DtxR is a two-domain protein that contains two structurally and functionally distinct metal binding sites. Here, we investigate the molecular steps associated with activation by Ni(II)Cl(2) and Cd(II)Cl(2).

Prolylpeptide binding by the prokaryotic SH3-like domain of the diphtheria toxin repressor: a regulatory switch.

Diphtheria toxin repressor (DtxR) regulates the expression of iron-sensitive genes in Corynebacterium diphtheriae, including the diphtheria toxin gene. DtxR contains an N-terminal metal- and DNA-binding domain that is connected by a proline-rich flexible peptide segment (Pr) to a C-terminal src homology 3 (SH3)-like domain. We determined the solution structure of the intramolecular complex formed between the proline-rich segment and the SH3-like domain by use of NMR spectroscopy.

Genetic and biophysical studies of diphtheria toxin repressor (DtxR) and the hyperactive mutant DtxR(E175K) support a multistep model of activation.

The diphtheria toxin repressor (DtxR) from Corynebacterium diphtheriae is the prototypic member of a superfamily of transition metal ion-activated transcriptional regulators that have been isolated from Gram-positive prokaryotes. Upon binding divalent transition metal ions, the N-terminal domain of DtxR undergoes a dynamic structural organization leading to homodimerization and target DNA binding. We have used site-directed mutagenesis and NMR analysis to probe the mechanism by which apo-DtxR transits from an inactive to a fully active repressor upon metal ion binding.

Characterization of the role of the divalent metal ion-dependent transcriptional repressor MntR in the virulence of Staphylococcus aureus.

DtxR-type metal ion-dependent repressors, present in many bacterial pathogens, may regulate expression of virulence genes such as that encoding diphtheria toxin. SirR, a DtxR homologue initially identified in Staphylococcus epidermidis, governs the expression of the adjacent sitABC operon encoding a putative metal ion ABC transporter system. We identified a sirR homologue, mntR, in Staphylococcus aureus and demonstrated by gel shift assay that the corynebacterial repressor DtxR binds to the S.