Treatment with recombinant interferon-β reduces inflammation and slows cartilage destruction in the collagen-induced arthritis model of rheumatoid arthritis

We investigated the therapeutic potential and mechanism of action of IFN-β protein for the treatment of rheumatoid arthritis (RA). Collagen-induced arthritis was induced in DBA/1 mice. At the first clinical sign of disease, mice were given daily injections of recombinant mouse IFN-β or saline for 7 days. Disease progression was monitored by visual clinical scoring and measurement of paw swelling. Inflammation and joint destruction were assessed histologically 8 days after the onset of arthritis. Proteoglycan depletion was determined by safranin O staining. Expression of cytokines, receptor activator of NF-κB ligand, and c-Fos was evaluated immunohistochemically. The IL-1-induced expression of IL-6, IL-8, and granulocyte/macrophage-colony-stimulating factor (GM-CSF) was studied by ELISA in supernatant of RA and osteoarthritis fibroblast-like synoviocytes incubated with IFN-β. We also examined the effect of IFN-β on NF-κB activity. IFN-β, at 0.25 μg/injection and higher, significantly reduced disease severity in two experiments, each using 8–10 mice per treatment group. IFN-β-treated animals displayed significantly less cartilage and bone destruction than controls, paralleled by a decreased number of positive cells of two gene products required for osteoclastogenesis, receptor activator of NF-κB ligand and c-Fos. Tumor necrosis factor α and IL-6 expression were significantly reduced, while IL-10 production was increased after IFN-β treatment. IFN-β reduced expression of IL-6, IL-8, and GM-CSF in RA and osteoarthritis fibroblast-like synoviocytes, correlating with reduced NF-κB activity. The data support the view that IFN-β is a potential therapy for RA that might help to diminish both joint inflammation and destruction by cytokine modulation.     

NMR and homology modeling studies of copper(II)-halocyanin from Natronobacterium pharaonis bacteria

Halocyanin from the haloalkaliphilic archaean Natronobacterium pharaonis is a peripheral membrane type 1 blue copper protein with a single polypeptide chain of 163 amino acid residues. Halocyanin participates as putative electron carrier protein associated to an electron acceptor role for a terminal oxidase and has the lowest redox potential value reported to date for a BCP. NMR studies and homology modeling calculations were performed to evaluate the electronic properties of Cu(II)-halocyanin from Natronobacterium pharaonis. The copper coordination site properties of Cu(II)-halocyanin are discussed. The ¹H NMR spectra, isotropic chemical shifts and relaxation times for halocyanin are compared with those of other BCPs such as azurin, amicyanin, plastocyanin and stellacyanin. The wild-type Cu(II)-halocyanin presents almost the same ¹H NMR spectra in comparison with Cu(II)-plastocyanin as expected from a similar coordination symmetry. However, minor differences were found. In order to get some insight on these differences, a computational model for Cu(II)-halocyanin from N. pharaonis was built. Model is based on sequential homology of halocyanin with two different families of proteins: plastocyanins and pseudoazurins. Homology modeling was performed using two different structural templates and copper ion was added for further refinement of the coordination site. Proposed structure was in good agreement with NMR experimental information and is the first three-dimensional model reported to date of an halocyanin. Small differences were found in the copper coordination site with respect to other BCP with known structure. This work is also an interesting example of expertise-driven homology modeling across different protein families.     

The human exosome: an autoantigenic complex of exoribonucleases in myositis and scleroderma

The anti-PM/Scl autoantibodies are known to characterize a subset of autoimmune patients with myositis, scleroderma (Scl), and the PM/Scl overlap syndrome. The major autoantigens that are recognized by anti-PM/Scl autoantibodies are designated PM/Scl-100 and PM/Scl-75. These autoantigens have been reported to associate into a large complex consisting of 11 to 16 proteins and to play a role in ribosome synthesis. Recently, it was discovered that the PM/Scl complex is the human counterpart of the yeast (Saccharomyces cerevisiae) exosome, which is an RNA-processing complex consisting of 11 3' → 5' exoribonucleases. To date, 10 human exosome components have been identified, although only some of these were studied in more detail. In this review, we discuss some recent advances in the characterization of the PM/Scl complex.