Production of a Lung Surfactant SP-B Mimic

DESCRIPTION (provided by applicant): Surfactant Protein B (SP-B) is crucial in the function of native lung surfactant, and is equally important for activity in clinical exogenous surfactants as well. Based on the known three-dimensional structures of prote ins in the Saposin class, early SP-B models predicted that the disulfide cross-linked, N- and C-terminal domains fold as functionally essential charged amphipathic helices. For the current Phase II SBIR research, we have designed and chemically synthesiz ed a 41 residue Super Mini-B (S-MB) peptide construct that emulates many of the in vitro and in vivo structural and functional properties of the 79 residue native protein. This S-MB peptide has activity exceeding that of the promising 34 amino acid Mini-B peptide studied in our completed Phase I SBIR and initial Phase II proposal (April, 2007). In the current application, S-MB peptide is combined with synthetic lipids to generate two complementary fully-synthetic exogenous lung surfactants (Minisurf(tm) and Minisurf-R(tm)) that have extremely high activity and commercial potential. Two types of synthetic lipids are utilized to allow the production of these S-MB surfactants: (i) a mix of synthetic lipids (L) modeled after those in native lung surfactant; and (ii) novel phospholipase-resistant lipids (RL) synthesized to have enhanced surface properties as components in therapeutic surfactants plus reduced degradation in inflammatory lung injuries where lytic enzymes are present in increased concentrations in pu lmonary tissue. In the current grant, we develop commercially viable production and quality-control methods for S-MB peptide and active synthetic L-SMB (Minisurf(tm)) and RL-S-MB (Minisurf-R(tm)) surfactants for treating acute respiratory failure in the Ne onatal Respiratory Distress Syndrome (NRDS), clinical Acute Lung Injury (ALI), and the Acute Respiratory Distress Syndrome (ARDS). Minisurf(tm) and Minisurf-R(tm) surfactants can also potentially be used in novel pulmonary delivery systems for antibiotics, anti-inflammatory agents, and genetic material. This Phase II SBIR proposal comprises Aims leading to the following key Milestones: 1) to define and establish process development activities required to produce commercially-viable quantities of purified ac tive S-MB and; 2) to demonstrate that S-MB peptide can be reproducibly formulated and quality-controlled in final Minisurf(tm) and Minisurf-R(tm) formulations that have significant potential advantages in production economy, surface activity, inhibition re sistance, and physiological activity compared to current animal-derived and synthetic surfactant drug products while exhibiting minimal toxicity. PUBLIC HEALTH RELEVANCE: This SBIR research will lead to the development and production of novel fully synthet ic exogenous surfactants having significant advantages in production economy, activity, and inhibition resistance for future clinical use in treating prevalent and severe respiratory diseases (NRDS, ALI, and ARDS). This SBIR Phase II application wi ll synthesize, quality-control, and define the high activity of synthetic lung surfactants (Minisurf(tm) and Minisurf-R(tm)) based on the novel synthetic peptide Super Mini-B (S-MB), a 41 residue construct incorporating key functional domains of full-lengt h lung surfactant protein (SP)-B. This S-MB peptide has been proven in preliminary studies to be even more active than the Mini-B (MB) peptide used in our successful Phase I studies. The synthetic S-MB surfactants of this Phase II proposal are designed to have significant activity in the therapy of the neonatal respiratory distress syndrome (NRDS), clinical acute lung injury (ALI), and the acute respiratory distress syndrome (ARDS). Minisurf(tm) formulations contain the S-MB peptide combined with synthetic lipids (L) reflecting those in native surfactant, and Minisurf-R(tm) formulations contain S-MB combined with novel phospholipase-resistant lipids (RL) with