A Process for the Design and Development of Novel Bone Morphogenetic Protein-7 (BMP-7) Mimetics With an Example: THR-184.

Growth Factors have been evaluated as therapeutic targets for the treatment of a broad spectrum of diseases. Because they are proteins with pleiotropic effects, the quest to harness their beneficial effects has presented challenges. Most Growth Factors operate at the extracellular-receptor level and have natural feedback mechanisms that modulate their effects. As proteins, they are difficult and expensive to manufacture. Frequently proteins must be administered parenterally, may invoke an immune response, and may be neutralized by naturally occurring inhibitors. To circumvent these limitations, we have undertaken an effort to develop mimetics for the Bone Morphogenetic Protein (BMP) signaling pathway effects that incorporate the beneficial effects, eliminate the deleterious effects, and thereby create effective drug-like compounds.To this end, we have designed and tested a family of small peptide BMP mimetics. The design used the three-dimensional structure of BMP-7 to identify likely active surface regions. Lead sequences were then optimized based on in vitro assays that examine the selective binding to BMP receptors, demonstrate the phosphorylation of Smad-1,5,8, detect anti-apoptosis and anti-inflammation, and block the epithelial to mesenchymal transition (EMT) in renal tubular epithelial cells. These sequences were further optimized using in vivo assays of the attenuation of acute kidney injury in a rat-model of unilateral clamp ischemic reperfusion. This process uses a Structure Variance Analysis algorithm (SVA) to identify structure/activity relationships. One member of this family, THR-184, is an agonist of BMP signaling and a potent antagonist of TGFß signaling. This small peptide mimetic inhibits inflammation, apoptosis, fibrosis and reverses epithelial to mesenchymal transition (EMT) by regulating multiple signaling pathways involved in the cellular injury of multiple organs. Its effects have been shown to control Acute Kidney Injury (AKI). THR-184 has progressed through phase I and II clinical trials for the prevention of Cardio-Vascular Surgery (CVS) associated AKI. This work provides a roadmap for the development of other growth factor mimetics and demonstrates how we might harness their therapeutic potential.

Bone morphogenetic protein-7 from serum of pregnant mice is available to the fetus through placental transfer during early stages of development.

BACKGROUND: BMP-7 is an important mediator of metanephric mesenchyme differentiation during kidney development. Gene knockout studies have shown that BMP-7 null mutation mice die shortly after birth due to renal failure, although the induction of metanephric structures has initially occurred (E11-E13). MATERIALS AND METHODS: Iodinated BMP-7 was injected into the tail vein of pregnant mice and its availability to tissues and fetuses was further analyzed by tissue uptake, LM autoradiography and SDS-PAGE electrophoresis. RESULTS: Studies on the distribution of 125I-BMP-7 injected through the tail vein of pregnant mice indicated that 125I-BMP-7 passed across the placenta and localized in developing fetal organs, in particular kidneys, up to day 14 of gestation. At later stages of pregnancy 125I-BMP-7 did not pass the trophoblasts of the placental barrier and did not enter the fetal blood vessels. CONCLUSION: The analysis of the distribution of 125I-BMP-7 from pregnant mice to fetal organs, in particular the kidney, suggests a cross-over of maternal circulating BMP-7 to the fetus through the placental barrier.

Activin-like kinase 3 is important for kidney regeneration and reversal of fibrosis.

Molecules associated with the transforming growth factor ß (TGF-ß) superfamily, such as bone morphogenic proteins (BMPs) and TGF-ß, are key regulators of inflammation, apoptosis and cellular transitions. Here we show that the BMP receptor activin-like kinase 3 (Alk3) is elevated early in diseased kidneys after injury. We also found that its deletion in the tubular epithelium leads to enhanced TGF-ß1-Smad family member 3 (Smad3) signaling, epithelial damage and fibrosis, suggesting a protective role for Alk3-mediated signaling in the kidney. A structure-function analysis of the BMP-Alk3-BMP receptor, type 2 (BMPR2) ligand-receptor complex, along with synthetic organic chemistry, led us to construct a library of small peptide agonists of BMP signaling that function through the Alk3 receptor. One such peptide agonist, THR-123, suppressed inflammation, apoptosis and the epithelial-to-mesenchymal transition program and reversed established fibrosis in five mouse models of acute and chronic renal injury. THR-123 acts specifically through Alk3 signaling, as mice with a targeted deletion for Alk3 in their tubular epithelium did not respond to therapy with THR-123. Combining THR-123 and the angiotensin-converting enzyme inhibitor captopril had an additive therapeutic benefit in controlling renal fibrosis. Our studies show that BMP signaling agonists constitute a new line of therapeutic agents with potential utility in the clinic to induce regeneration, repair and reverse established fibrosis.

Bone morphogenetic protein-7 reduces the severity of colon tissue damage and accelerates the healing of inflammatory bowel disease in rats.

Bone morphogenetic protein-7 (BMP-7) is a growth and differentiation factor and belongs to the TGF-beta superfamily of proteins. Previous studies have shown an abundant expression of BMP-7 in the developing intestine and an association with a perturbed BMP/SMAD downstream signaling leading to a malignant phenotype and inflammation in the gut. In the present study, we have evaluated the effect of systemically administered recombinant human BMP-7 against trinitrobenzenesulfonic (TNBS) acid induced inflammatory bowel disease (IBD) in rats. The TNBS administered rats treated with BMP-7 have developed much less severe form of colitis based on macroscopic and histological scoring when administered 1.5 h before or 24 h after colitis induction. Bioavailability studies in healthy rats have revealed that significant portion (3.6%) of i.v. administered BMP-7 is targeted for BMP-7 receptors in the stomach and ileum, respectively, suggesting its availability to target tissue upon administration. Immunohistochemical and RT-PCR analyses have shown elevated expression of pro-inflammatory (IL-6, TNF-beta, ICAM-1) and pro-fibrogenic (TGF-beta) cytokines, and BMP-7 treatment significantly reduced their expression in the intestine; among which the suppression of IL-6 appeared to be the most important. Taken together, the results of this study suggest that BMP-7 plays an important role in the regulation of anti-inflammatory response in the adult gut tissue.