E-64c-Hydrazide Based Cathepsin C Inhibitors: Optimizing the Interactions with the S1'-S2' Area

The zymogens of the neutrophil serine proteases elastase, proteinase 3, and cathepsin G are converted proteolytically into their pro-inflammatory active forms by the action of cathepsin C. The inhibition of this cysteine protease therefore is an interesting therapeutic approach for the treatment of inflammatory disorders with a high neutrophil burden such as COPD. Based on E-64c-hydrazide as lead structure, we have recently developed a covalently acting cathepsin C inhibitor using a n-butyl residue attached at the amine nitrogen of the hydrazide moiety to efficiently address the deep hydrophobic S2 pocket. To further optimize the affinity and selectivity profile of this inhibitor, the S1'-S2' area was now investigated by a combinatorial approach, showing that Nle-tryptamide is a ligand superior to the initially used Leu-isoamylamide. Using the neutrophil precursor line U937 as a cell culture model, this optimized inhibitor blocks the intracellular cathepsin C activity and thereby suppresses the activation of neutrophil elastase.

Synthesis of Hybrid Tripeptide Peptidomimetics Containing Dehydroamino Acid and Aminophosphonic Acid in the Chain and Evaluation of Their Activity toward Cathepsin C

Synthesis of a new group of hybrid phosphonodehydropeptides composed of glycyl-(Z)-dehydrophenylalanine and structurally variable aminophosphonates alongside with investigations of their activity towards cathepsin C are presented. Obtained results suggest that the introduction of (Z)-dehydrophenylalanine residue into the short phosphonopeptide chain does induce the ordered conformation. Investigated peptides appeared to act as weak or moderate inhibitors of cathepsin C.

Human breast milk oligosaccharides attenuate necrotizing enterocolitis in rats by suppressing mast cell accumulation, DPPI activity and TLR4 expression in ileum tissue, and regulating mitochondrial damage of Caco-2 cells

Necrotizing enterocolitis (NEC), a devastating infant disease characterized by severe intestinal necrosis, its pathogenesis is poorly understood, but appears to be multifactorial and highly associated with immaturity of gastrointestinal tract and immature innate-immune system. Breast-milk is effective strategy to protect infants against NEC. This study is using a NEC rat model to investigate the pathological mechanism of NEC involved intestinal-damages, and the therapeutic mechanism of sialylated human milk oligosaccharides (SHMOs) on NEC rats; also using cell model to investigate the effects of SHMOs on colon-epithelial cells (Caco-2) in-vitro. Extraction and characterization of SHMOs from breast milk, establishment of a NEC rat model, histopathological analysis and mast cell accounting of the terminal ileum were taken; The levels of DPPI, TLR4, IL-6, TNF-α, MMP-2/9 and glutathione were measured using various methods. Caco-2 cells were pre-treated with SHMOs and cultured with LPS, histamine, chymase or DPPI, cell viabilities and mitochondrial membrane potential were examined; flow cytometry was used to detect cell cycle. The accumulation of mast cells was found in the ileum of NEC rats, but prohibited by SHMOs treatment; the increased levels of TLR4, DPPI, IL-6, TNF-α, MMP-2/9 in NEC ileum were suppressed by SHMOs in-vivo. SHMOs prevented Caco-2 cells from LPS, histamine, chymase induced damages by surviving cell viability, regulating G0/G1 and S phase in cell cycles, and increasing mitochondrial membrane potential. These findings provide a new insight into the pharmacological mechanism of SHMOs treatment for NEC and suggest that SHMOs needs well attention for therapeutic aims.