No abstract

We conducted a multicenter prospective trial to evaluate the efficacy, safety and pharmacokinetics of a single dose of rituximab (375 mg/m(2) body surface area) for the treatment of children with refractory steroid-dependent nephrotic syndrome (SDNS). All patients (n = 12) were able to discontinue steroids at a median of 74 days after treatment. The frequency of relapses per 6 months was significantly reduced and the steroid-free period per 6 months was significantly increased after treatment compared with those before treatment. The condition in nine of the patients (75%) relapsed at a median of 129 days after treatment, and seven patients were given additional rituximab due to steroid dependency. Most of the relapses developed simultaneously with recovery of B-cells. However, three patients (25%) did not have a relapse with B-cell recovery and the disease was kept in remission for more than 1 year. None of the patients developed life-threatening adverse events. This is the first report of a prospective study of a single dose of rituximab for refractory SDNS. Treatment with a single dose of rituximab may be effective for refractory SDNS, but its efficacy to prevent relapses was transient in most of the patients.

alphaB-crystallin in cells can be phosphorylated at three serine residues in response to stress or during mitosis (Ito, H., Okamoto, K., Nakayama, H., Isobe, T., and Kato, K. (1997) J. Biol. Chem. 272, 29934-29941 and Kato, K., Ito, H., Kamei, K., Inaguma, Y., Iwamoto, I., and Saga, S. (1998) J. Biol. Chem. 273, 28346-28354). In the present study, we determined effects of phosphorylation of alphaB-crystallin on its oligomerization state, mainly by using site-directed mutagenesis, in which all three phosphorylation sites were substituted with aspartate to mimic the phosphorylation state (3D-alphaB). From results of sucrose density gradient centrifugation, we found that wild type alphaB-crystallin (wt-alphaB) and 3D-alphaB sedimented in fractions corresponding to apparent molecular masses of about 500 and 300 kDa, respectively. Chaperone-like activity of 3D-alphaB was significantly weaker than that of wt-alphaB. When wt-alphaB and 3D-alphaB were expressed in COS-m6 cells, they sedimented at positions corresponding to apparent molecular masses of about 500 and 100 kDa, respectively. In U373 MG human glioma cells, alphaB-crystallin was observed as large oligomers with apparent molecular masses about 500 kDa and the oligomerization size was reduced after phosphorylation induced by phorbol 12-myristate 13-acetate and okadaic acid. Coexpression of luciferase and wt-alphaB or 3D-alphaB in Chinese hamster ovary cells caused protection of the enzyme from heat inactivation although the degree of protection with 3D-alphaB was less than that with wt-alphaB. From these observations, it is suggested that phosphorylation of alphaB-crystallin causes dissociation of large oligomers to smaller sizes molecules and reduction of chaperone-like activity, like in the case of HSP27.

The aim of this study was to establish the efficacy and safety of rituximab in refractory nephrotic syndrome (NS). Members of the International Paediatric Nephrology Association were asked to retrospectively fill in a questionnaire with details on the use of rituximab in their centres. We divided the data into three groups: group 1, patients with steroid-dependent and frequently relapsing NS; group 2, with steroid-resistant NS; group 3, with post-transplant recurrence of NS. Seventy questionnaires from 25 centres described the outcome of 28, 27 and 15 patients in groups 1, 2 and 3, respectively. Of these, 82% of patients in group 1, 44% of patients in group 2 and 60% of patients in group 3 had a good initial response. Side effects were observed in 27% of the patients, and these were mostly acute reactions. We present a large multicentre series of children with refractory NS. Children in group 1 showed the best response. The good initial response in group 3 can be biased by the accompanying treatments that were administered at the same time as rituximab. Controlled prospective trials are required to establish the value of rituximab in idiopathic NS.

The immunofluorescence localization of ␣B-crystallin in U373 MG human glioma cells with an antibody specific for ␣B-crystallin that had been phosphorylated at Ser-45 revealed an intense staining of cells in the mitotic phase of the cell cycle. Phosphorylated forms of ␣B-crystallin in mitotic cells were detected in all cell lines examined and in tissue sections of mouse embryos. Increases in the levels of ␣B-crystallin that had been phosphorylated at Ser-45 and Ser-19, but not at Ser-59, were detected biochemically by isoelectric focusing or SDSpolyacrylamide gel electrophoresis and a subsequent Western blot analysis of extracts of cells collected at the mitotic phase. When we estimated the phosphorylation activity specific for ␣B-crystallin in extracts of mitotic U373 MG cells, using the amino-terminal 72-amino acid peptide derived from unphosphorylated ␣B2-crystallin as the substrate, we found that the activities responsible for the phosphorylation of Ser-45 and Ser-19 were markedly enhanced but that the activity responsible for the phosphorylation of Ser-59 was suppressed ␣-Crystallin, a major structural protein of the vertebrate eye lens, is a polymeric protein with a molecular mass of about 800 kDa. The ␣-crystallin of the bovine lens is composed predominantly of two types of polypeptide, the A (␣A1 and ␣A2) and B (␣B1 and ␣B2) subunits (1). ␣A1 and ␣B1 are the phosphorylated forms of the primary gene products, ␣A2 and ␣B2 (2, 3). The molecular mass of each subunit is about 20 kDa, and the similarity between the primary structures of the two subunits is greater than 50% (4). The ␣-crystallins also share sequence similarity with the small heat shock proteins (hsps) 1 of numerous species (5). Because of the striking similarities among the primary structures of the carboxyl-terminal half of each molecule (the ␣-crystallin domain), ␣A-crystallin, ␣B-crystallin, hsp27, and p20 (6) are considered to be members of the ␣-crystallin small hsp family in vertebrates (7,8).A common feature of small hsps is their formation of large oligomeric complexes such as ␣A-crystallin and ␣B-crystallin in the lens. In the skeletal muscle, ␣B-crystallin, hsp27, and p20 seem to form a large heteropolymer, because the three proteins were copurified from the extract and coimmunoprecipitated with antibodies against each of the three proteins (6, 9). The ␣-crystallin domain of each small hsp was suggested to be important for this complex formation and the chaperone activity (8). Both ␣A-crystallin (10) and ␣B-crystallin (11) are also present in nonlenticular tissues, and the expression of ␣B-crystallin, but not ␣A-crystallin and p20, is induced in cells under various stressful conditions, as is hsp27 (12, 13).The major posttranscriptional modifications of the ␣-crystallin small hsp family are due to the phosphorylation of serine residues. The phosphorylation of hsp27 by mitogen-activated protein (MAP) kinase-activated protein (MAPKAP) kinase-2 is enhanced when cells are exposed to heat (14, 15) or chemicals (16). p20 in vascular smooth m...

We present the cases of two children with steroid-resistant nephrotic syndrome (SRNS) who were treated with rituximab (anti-CD20 monoclonal antibody). Both were resistant to conventional therapy, and renal biopsy showed focal segmental glomerulosclerosis (FSGS). Combination therapy with methylprednisolone pulse therapy and plasmapheresis was the only way to decrease proteinuria. However, the patients suffered severe reactions to steroid treatment. We therefore treated them with rituximab in a single dose of 375 mg/m(2), which resulted in the rapid clearing of circulating CD19-positive B cells. One month after rituximab treatment, both achieved partial remission; one patient has maintained complete remission for 8 months, and the other relapsed 8 months after the first rituximab treatment with the recovery of peripheral B-cell counts and received a second rituximab treatment. She achieved complete remission 5 months after the second course and has maintained the remission for 2 months. We conclude that rituximab may be an effective treatment for refractory SRNS with FSGS.

No abstract

Molecular chaperones and the ubiquitin-proteasome pathway are known to participate in the quality control of proteins in cells. In this study, we examined the responses of small heat shock proteins to proteasome inhibitors to clarify their roles under conditions where misfolded proteins are abnormally accumulated. HSP27 and alphaB-crystallin accumulated in both soluble and, more prominently, insoluble fractions after exposure to MG-132, a proteasome inhibitor. Enhanced expression of mRNAs for HSP27 and alphaB-crystallin was observed, suggesting transcriptional activation. Phosphorylation of HSP27 and alphaB-crystallin in cells treated with MG-132 was enhanced concomitantly with activation of p38 and p44/42 MAP kinase pathways. Immunofluorescence analysis revealed that exposure to proteasome inhibitors induced the formation of aggresomes in U373 MG cells, to which HSP27 and alphaB-crystallin were recruited. However, phosphorylation was not required for this accumulation in aggresomes. Thus, HSP27 and alphaB-crystallin are increased, phosphorylated and localized in aggresomes when proteasome activity is inhibited.