Oligonucleotide-targeting periostin ameliorates pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal disease with a median survival of 3-4 years after diagnosis. It is the most frequent form of a group of interstitial pneumonias of unknown etiology. Current available therapies prevent deterioration of lung function but no therapy has shown to improve survival. Periostin is a matricellular protein of the fasciclin 1 family. There is increased deposition of periostin in lung fibrotic tissues. Here we evaluated whether small interfering RNA or antisense oligonucleotide against periostin inhibits lung fibrosis by direct administration into the lung by intranasal route. Pulmonary fibrosis was induced with bleomycin and RNA therapeutics was administered during both acute and chronic phases of the disease. The levels of periostin and transforming growth factor-ß1 in airway fluid and lung tissue, the deposition of collagen in lung tissue and the lung fibrosis score were significantly reduced in mice treated with siRNA and antisense against periostin compared to control mice. These findings suggest that direct administration of siRNA or antisense oligonucleotides against periostin into the lungs is a promising alternative therapeutic approach for the management of pulmonary fibrosis.

Substrate specificity analysis of microbial transglutaminase using proteinaceous protease inhibitors as natural model substrates.

The substrate specificity of microbial transglutaminase (MTG) from Streptomyces mobaraensis (formerly categorized Streptoverticillium) was studied using a Streptomyces proteinaceous protease inhibitor, STI2, as a model amine-donor substrate. Chemical modification and mutational analysis to address the substrate requirements for MTG were carried out around the putative reactive site region of STI2 on the basis of the highly refined tertiary structure and the solvent accessibility index of Streptomyces subtilisin inhibitor, SSI, a homolog of STI2. The results suggest that the P1 reactive center site (position 70 of STI2) for protease subtilisin BPN' or trypsin may be the prime Lys residue that can be recognized by MTG, when succinylated beta-casein was used as a partner Gln-substrate. It is characteristic in that the same primary enzyme contact region of STI2 is shared by both enzymes, MTG and proteases. For quantitative analysis of the TG reaction, we established an ELISA-based monitoring assay system using an anti-SSI polyclonal antibody highly cross-reactive with STI2. Site-specific STI2 mutants were prepared by an Escherichia coli expression-secretion vector system and subjected to the assay system. We reached several conclusions concerning the nature of the flanking amino acid residues affecting the MTG reactivity of the substrate Lys residue: (i) site-specific mutations from Asn to Lys or Arg at position 69 preceding the amine-donor 70Lys, led to enhanced substrate reactivity; (ii) amino acid replacement at 67Ile with Ser led to higher substrate reactivity, (iii) additive effects were obtained by a combination of the positive mutations at positions 67 and 69 as described above, and (iv) Gly at position 65 might be essential for MTG reaction. Moreover, the substrate specificity of guinea pig liver tissue transglutaminase (GTG) was compared with that of MTG using STI2 and its mutants. In contrast to MTG, replacement of Gly by Asp at position 65 was the most favorable for substrate reactivity. Also, 70Lys appeared not to be a prime amine-donor site for GTG-mediated cross-linking, suggesting a difference in substrate recognition between MTG and GTG.