Development of a back-titration assay to quantitate functional lympho-epithelial Kazal-type inhibitors (LEKTI) in skin samples.

The lympho-epithelial Kazal-type inhibitors (LEKTI) are key to control skin turnover, and their absence causes Netherton syndrome. For clinical sample testing of LEKTI-based therapies, a robust analytical method to measure LEKTI-like activity in skin is required. This work reports on the development of a back-titration method to determine incremental LEKTI-like activity in skin samples. The method meets the analytical requirements for study sample testing, and reliable quantification can be achieved with negligible skin matrix interference. This assay does not provide analyte identity, but it can be used to measure treatment-driven increments of LEKTI-like activity within the skin epidermis.

Controlling the Growth of the Skin Commensal Staphylococcus epidermidis Using d-Alanine Auxotrophy.

Using live microbes as therapeutic candidates is a strategy that has gained traction across multiple therapeutic areas. In the skin, commensal microorganisms play a crucial role in maintaining skin barrier function, homeostasis, and cutaneous immunity. Alterations of the homeostatic skin microbiome are associated with a number of skin diseases. Here, we present the design of an engineered commensal organism, Staphylococcus epidermidis, for use as a live biotherapeutic product (LBP) candidate for skin diseases. The development of novel bacterial strains whose growth can be controlled without the use of antibiotics or genetic elements conferring antibiotic resistance enables modulation of therapeutic exposure and improves safety. We therefore constructed an auxotrophic strain of S. epidermidis that requires exogenously supplied d-alanine. The S. epidermidis NRRL B-4268 Δalr1 Δalr2 Δdat strain (SEΔΔΔ) contains deletions of three biosynthetic genes: two alanine racemase genes, alr1 and alr2 (SE1674 and SE1079), and the d-alanine aminotransferase gene, dat (SE1423). These three deletions restricted growth in d-alanine-deficient medium, pooled human blood, and skin. In the presence of d-alanine, SEΔΔΔ colonized and increased expression of human ß-defensin 2 in cultured human skin models in vitro. SEΔΔΔ showed a low propensity to revert to d-alanine prototrophy and did not form biofilms on plastic in vitro. These studies support the potential safety and utility of SEΔΔΔ as a live biotherapeutic strain whose growth can be controlled by d-alanine.IMPORTANCE The skin microbiome is rich in opportunities for novel therapeutics for skin diseases, and synthetic biology offers the advantage of providing novel functionality or therapeutic benefit to live biotherapeutic products. The development of novel bacterial strains whose growth can be controlled without the use of antibiotics or genetic elements conferring antibiotic resistance enables modulation of therapeutic exposure and improves safety. This study presents the design and in vitro evidence of a skin commensal whose growth can be controlled through d-alanine. The basis of this strain will support future clinical studies of this strain in humans.

Human growth hormone-releasing factor (hGRF)1-29-albumin bioconjugates activate the GRF receptor on the anterior pituitary in rats: identification of CJC-1295 as a long-lasting GRF analog.

In vivo bioconjugation to the free thiol on Cys34 of serum albumin by a strategically placed reactive group on a bioactive peptide is a useful tool to extend plasma half-life. Three maleimido derivates of human GH-releasing factor (hGRF)(1-29) were synthesized and bioconjugated to human serum albumin ex vivo. All three human serum albumin conjugates showed enhanced in vitro stability against dipeptidylpeptidase-IV and were bioactive in a GH secretion assay in cultured rat anterior pituitary cells. When the maleimido derivatives were individually administered sc to normal male Sprague Dawley rats, an acute secretion of GH was measured in plasma. The best compound, CJC-1295, showed a 4-fold increase in GH area under the curve over a 2-h period compared with hGRF(1-29). CJC-1295, a tetrasubstituted form of hGRF(1-29) with an added N epsilon-3-maleimidopropionamide derivative of lysine at the C terminus, was selected for further pharmacokinetic evaluation, where it was found to be present in plasma beyond 72 h. A Western blot analysis of the plasma of a rat injected with CJC-1295 showed the presence of a CJC-1295 immunoreactive species on the band corresponding to serum albumin, appearing after 15 min and remaining in circulation beyond 24 h. These results led to the identification of CJC-1295 as a stable and active hGRF(1-29) analog with an extended plasma half-life.

Synthesis and evaluation of insulin-human serum albumin conjugates.

A series of human insulin maleimido derivatives with short and long linkers was synthesized by exploiting the variations in the pK(a) values and environment of the three amino groups present in the protein. The syntheses were accomplished in organic solvent because of maleimide's instability in basic aqueous media. The derivatives thus obtained were conjugated to the free thiol on Cys34 of human serum albumin (HSA) and purified. A structure-activity relationship based on in vitro receptor binding and activation results for this series of insulin-HSA conjugates showed that the best compounds were attached at the B1 position of insulin with either short or long linkers. Two conjugates were administered subcutaneously to streptozotocin-induced diabetic rats and found to possess blood glucose normalizing activity up to 8 h post-administration. The return to diabetic plasma glucose levels was not observed within the time frame of the experiment (48 h). In comparison, the insulin-treated group's normalization activity lasted 2 h and returned to a diabetic level at 8 h. The onset of the conjugate activities were delayed by 1 h when compared to the activity of human insulin. The study results led to the identification of CJC-1575 as a potent and long lasting human insulin analogue.

Kringle 5 peptide-albumin conjugates with anti-migratory activity.

Three peptide fragments of the kringle 5 region of plasminogen and their respective N- and C-terminus maleimido derivatives conjugated to Cys34 of human serum albumin were evaluated in vitro using a human umbilical vein endothelial cell (HUVEC) migration assay and a human plasma stability assay. The N-terminus maleimido derivative of the 64 to 74 segment of kringle 5 conjugated to human serum albumin possessed remarkable anti-migratory activity.

Synthesis and in vitro analysis of atrial natriuretic peptide-albumin conjugates.

Atrial natriuretic peptide (ANP) is a clinically useful anti-hypertensive hormone. Maleimide derivatives of ANP have been synthesized and conjugated to cysteine-34 of human serum albumin. The conjugates were analyzed to assess their stability, receptor binding affinity and ability to stimulate guanylyl-cyclase activity in rat lung fibroblasts.

Identification of CJC-1131-albumin bioconjugate as a stable and bioactive GLP-1(7-36) analog.

A series of analogs of GLP-1(7-36) amide containing a Nepsilon-(2-[2-[2-(3-maleimidopropylamido)ethoxy]ethoxy]acetyl)lysine has been synthesized and the resulting derivatives were bioconjugated to Cys34 of human serum albumin (HSA). The GLP-1-HSA bioconjugates were analyzed in vitro to assess the stabilizing effect of bioconjugation in the presence of DPP-IV as well as GLP-1 receptor binding and activation. Compound 9 (CJC-1131) having the point of attachment to albumin at the C-terminal of GLP-1 and a D-alanine substitution at position 8 was identified as having the best combination of stability and bioactivity.

Peptidomimetics of efflux pump inhibitors potentiate the activity of levofloxacin in Pseudomonas aeruginosa.

Several classes of peptidomimetics of the efflux pump inhibitor D-ornithine-D-homophenylalanine-3-aminoquinoline (MC-02,595) have been prepared and evaluated for their ability to potentiate the activity of the fluoroquinolone levofloxacin in Pseudomonas aeruginosa. A number of the new analogues were as active or more active than the lead, demonstrating that a peptide backbone is not essential for activity.

The relationship between physicochemical properties, in vitro activity and pharmacokinetic profiles of analogues of diamine-containing efflux pump inhibitors.

Following the optimization of diamine-containing efflux pump inhibitors with respect to in vitro potentiation activity, in vivo stability and acute toxicity, we addressed the question of how to control the pharmacokinetic properties of the series. Upon intravenous administration in the rat, tissue levels of MC-04,124 (the lead compound) were high and prolonged compared to those in the serum. The lipophilicity and basicity of analogues of this compound were systematically varied, and effects on potency and pharmacokinetics explored. The ratio of drug levels in tissue versus serum was not significantly reduced in any of the active analogues examined.

MexAB-OprM-specific efflux pump inhibitors in Pseudomonas aeruginosa. Part 1: discovery and early strategies for lead optimization.

The identification of a series of compounds that specifically inhibit efflux by the MexAB-OprM pump system in Pseudomonas aeruginosa is described. Synthesis and in vitro structure-activity relationships (SARs) are outlined. Early leads lacked activity in animal models, and efforts to improve solubility and reduce serum protein binding by the introduction of polar groups are discussed.

Conformationally-restricted analogues of efflux pump inhibitors that potentiate the activity of levofloxacin in Pseudomonas aeruginosa.

Conformational restriction of the ornithine residue of the efflux pump inhibitor D-ornithine-D-homophenylalanine-3-aminoquinoline (MC-02,595, 2) furnished bioisosteric proline derivatives that were less toxic in vivo and as active as the lead in potentiating the activity of the fluoroquinolone levofloxacin via the inhibition of efflux pumps in Pseudomonas aeruginosa.