Targeted designed variants of alpha-2-macroglobulin (A2M) attenuate cartilage degeneration in a rat model of osteoarthritis induced by anterior cruciate ligament transection.

Background: The study was performed to evaluate whether targeted alpha-2-macroglobulin (A2M) variants have a similar or enhanced function at wild-type (wt)-A2M to attenuate cartilage degeneration in vivo.

Methods: In and ex-vivo experiment, bovine cartilage explants (BCE) were incubated with TNF-α and IL-1β with or without wt-A2M or A2M variants. Cartilage catabolism was measured in culture supernatant by sulfated glycosaminoglycan (sGAG).

Epigenetic dominance of prion conformers.

Although they share certain biological properties with nucleic acid based infectious agents, prions, the causative agents of invariably fatal, transmissible neurodegenerative disorders such as bovine spongiform encephalopathy, sheep scrapie, and human Creutzfeldt Jakob disease, propagate by conformational templating of host encoded proteins. Once thought to be unique to these diseases, this mechanism is now recognized as a ubiquitous means of information transfer in biological systems, including other protein misfolding disorders such as those causing Alzheimer's and Parkinson's diseases. To address the poorly understood mechanism by which host prion protein (PrP) primary structures interact with distinct prion conformations to influence pathogenesis, we produced transgenic (Tg) mice expressing different sheep scrapie susceptibility alleles, varying only at a single amino acid at PrP residue 136.

Platelet-rich plasma increases matrix metalloproteinases in cultures of human synovial fibroblasts.

Background: The effect of platelet-rich plasma on chondrocytes has been studied in cell and tissue culture. Less attention has been given to the effect of platelet-rich plasma on nonchondrocytic cell lineages within synovial joints, such as fibroblast-like synoviocytes, which produce cytokines and matrix metalloproteinases (MMPs) that mediate cartilage catabolism. The purpose of the present study was to determine the effect of platelet-rich plasma on cytokines and proteases produced by fibroblast-like synoviocytes.

Prions on the move.

Prions consist mainly, if not entirely, of PrP(Sc), an aggregated conformer of the host protein PrP(C). Prions come in different strains, all based on the same PrP(C) sequence, but differing in their conformations. The efficiency of prion transmission between species is usually low, but increases after serial transmission in the new host, suggesting a process involving mutation and selection.

Abrogation of complex glycosylation by swainsonine results in strain- and cell-specific inhibition of prion replication.

Neuroblastoma-derived N2a-PK1 cells, fibroblastic LD9 cells, and CNS-derived CAD5 cells can be infected efficiently and persistently by various prion strains, as measured by the standard scrapie cell assay. Swainsonine, an inhibitor of Golgi α-mannosidase II that causes abnormal N-glycosylation, strongly inhibits infection of PK1 cells by RML, 79A and 22F, less so by 139A, and not at all by 22L prions, and it does not diminish propagation of any of these strains in LD9 or CAD5 cells. Misglycosylated PrP(C) formed in the presence of swainsonine is a good substrate for conversion to PrP(Sc), and misglycosylated PrP(Sc) is fully able to trigger infection and seed the protein misfolding cyclic amplification reaction.

Transfer of a prion strain to different hosts leads to emergence of strain variants.

Prions consist mainly of PrP(Sc), a pathogenic conformer of host-encoded PrP(C). Prion populations with distinct phenotypes but associated with PrP(Sc), having the same amino acid sequence, constitute distinct strains. Strain identity is thought to be encoded by the conformation of PrP(Sc) and to be maintained by seeded conversion.

Prion strain mutation determined by prion protein conformational compatibility and primary structure.

Prions are infectious proteins composed of the abnormal disease-causing isoform PrPSc, which induces conformational conversion of the host-encoded normal cellular prion protein PrPC to additional PrPSc. The mechanism underlying prion strain mutation in the absence of nucleic acids remains unresolved. Additionally, the frequency of strains causing chronic wasting disease (CWD), a burgeoning prion epidemic of cervids, is unknown.

Darwinian evolution of prions in cell culture.

Prions are infectious proteins consisting mainly of PrP(Sc), a beta sheet-rich conformer of the normal host protein PrP(C), and occur in different strains. Strain identity is thought to be encoded by PrP(Sc) conformation. We found that biologically cloned prion populations gradually became heterogeneous by accumulating "mutants," and selective pressures resulted in the emergence of different mutants as major constituents of the evolving population.

The elk PRNP codon 132 polymorphism controls cervid and scrapie prion propagation.

The elk prion protein gene (PRNP) encodes either methionine (M) or leucine (L) at codon 132, the L132 allele apparently affording protection against chronic wasting disease (CWD). The corresponding human codon 129 polymorphism influences the host range of bovine spongiform encephalopathy (BSE) prions. To fully address the influence of this cervid polymorphism on CWD pathogenesis, we created transgenic (Tg) mice expressing cervid PrPC with L at residue 132, referred to as CerPrPC-L132, and compared the transmissibility of CWD prions from elk of defined PRNP genotypes, namely homozygous M/M or L/L or heterozygous M/L, in these Tg mice with previously described Tg mice expressing CerPrPC-M132, referred to as Tg(CerPrP) mice.

Prions in skeletal muscles of deer with chronic wasting disease.

The emergence of chronic wasting disease (CWD) in deer and elk in an increasingly wide geographic area, as well as the interspecies transmission of bovine spongiform encephalopathy to humans in the form of variant Creutzfeldt Jakob disease, have raised concerns about the zoonotic potential of CWD. Because meat consumption is the most likely means of exposure, it is important to determine whether skeletal muscle of diseased cervids contains prion infectivity. Here bioassays in transgenic mice expressing cervid prion protein revealed the presence of infectious prions in skeletal muscles of CWD-infected deer, demonstrating that humans consuming or handling meat from CWD-infected deer are at risk to prion exposure.

Transmission of prions from mule deer and elk with chronic wasting disease to transgenic mice expressing cervid PrP.

We generated mice expressing cervid prion protein to produce a transgenic system simulating chronic wasting disease (CWD) in deer and elk. While normal mice were resistant to CWD, these transgenic mice uniformly developed signs of neurological dysfunction approximately 230 days following intracerebral inoculation with four CWD isolates. Inoculated transgenic mice homozygous for the transgene array developed disease after approximately 160 days.