Elevated levels of a C-terminal agrin fragment identifies a new subset of sarcopenia patients.

Sarcopenia is a recently defined medical condition described as age-associated loss of skeletal muscle mass and function. Recently, a transgenic mouse model was described linking dispersal of the neuromuscular junction caused by elevated agrin degradation to the rapid onset of sarcopenia. These mice show a significant elevation of serum levels of a C-terminal agrin fragment (CAF) compared to wild-type littermates. A series of experiments was designed to ascertain the significance of elevated agrin degradation in the development of human sarcopenia. A quantitative Western blot method was devised to detect CAF in sera of humans. A first trial on consenting blood donors (n=169; age 19-74 years) detected CAF in the limited range of 2.76 ± 0.95 ng/ml. In sarcopenia patients (diagnosed according to clinical and instrumental standards) mean CAF levels were significantly elevated (p=9.8E10-9; n=73; age 65-87 years) compared to aged matched controls. Of all sarcopenia patients, 40% had elevated, non-overlapping CAF levels compared to controls. Evidence is presented for a pathogenic role of the agrin/neurotrypsin system in a substantial subset of sarcopenia patients. These patients are characterized by elevated CAF blood levels compared to aged-matched healthy volunteers suggesting the identification of an agrin-dependent form of sarcopenia. Elevated CAF levels in a large subpopulation of sarcopenic patients suggest the existence of a specific form of sarcopenia for which CAF could become a biomarker and a new target for therapeutic interventions. The feasibility of this approach was demonstrated by the development of a small molecule capable of inhibiting neurotrypsin in vitro and in vivo.

Discovery of novel, highly potent and selective beta-hairpin mimetic CXCR4 inhibitors with excellent anti-HIV activity and pharmacokinetic profiles.

Novel highly potent CXCR4 inhibitors with good pharmacokinetic properties were designed and optimized starting from the naturally occurring beta-hairpin peptide polyphemusin II. The design involved incorporating important residues from polyphemusin II into a macrocyclic template-bound beta-hairpin mimetic. Using a parallel synthesis approach, the potency and ADME properties of the mimetics were optimized in iterative cycles, resulting in the CXCR4 inhibitors POL2438 and POL3026. The inhibitory potencies of these compounds were confirmed in a series of HIV-1 invasion assays in vitro. POL3026 showed excellent plasma stability, high selectivity for CXCR4, favorable pharmacokinetic properties in the dog, and thus has the potential to become a therapeutic compound for application in the treatment of HIV infections (as an entry inhibitor), cancer (for angiogenesis suppression and inhibition of metastasis), inflammation, and in stem cell transplant therapy.