Insight into the PrPC-->PrPSc conversion from the structures of antibody-bound ovine prion scrapie-susceptibility variants

Prion diseases are associated with the conversion of the alpha-helix rich prion protein (PrPC) into a beta-structure-rich insoluble conformer (PrPSc) that is thought to be infectious. The mechanism for the PrPC-->PrPSc conversion and its relationship with the pathological effects of prion diseases are poorly understood, partly because of our limited knowledge of the structure of PrPSc. In particular, the way in which mutations in the PRNP gene yield variants that confer different susceptibilities to disease needs to be clarified. We report here the 2.5-A-resolution crystal structures of three scrapie-susceptibility ovine PrP variants complexed with an antibody that binds to PrPC and to PrPSc; they identify two important features of the PrPC-->PrPSc conversion. First, the epitope of the antibody mainly consists of the last two turns of ovine PrP second alpha-helix. We show that this is a structural invariant in the PrPC-->PrPSc conversion; taken together with biochemical data, this leads to a model of the conformational change in which the two PrPC C-terminal alpha-helices are conserved in PrPSc, whereas secondary structure changes are located in the N-terminal alpha-helix. Second, comparison of the structures of scrapie-sensitivity variants defines local changes in distant parts of the protein that account for the observed differences of PrPC stability, resistant variants being destabilized compared with sensitive ones. Additive contributions of these sensitivity-modulating mutations to resistance suggest a possible causal relationship between scrapie resistance and lowered stability of the PrP protein.     

Longterm course of mixed cryoglobulinemia in patients infected with hepatitis C virus

OBJECTIVE: To describe epidemiological, clinical, and immunological characteristics and the longterm course of persistent mixed cryoglobulinemia (MC) in patients infected with hepatitis C virus (HCV). METHODS: Retrospective study of HCV infected patients (HCV RNA positive) who had persistent positive MC, with 2 immunochemical typings of MC carried out after 24-month minimum interval. RESULTS: In total, 125 patients were studied, aged 52 +/- 13 years at diagnosis of MC, with duration of HCV infection of 18 +/- 10 years. At entry, 60 patients had type II MC, 53 patients had type III, and 12 patients had the oligoclonal type. At the second immunochemical typing, after a mean interval of 45 +/- 20 months, MC was type II in 72 patients, type III in 39 patients, and the oligoclonal type in 14 patients. The proportion of cases of MC with the same immunochemical type was higher among patients with type II (78%) than type III (59%) or oligoclonal MC (17%) (p < 0.01). The MC that changed turned more to type II (55.5%) than type III (29%) or the oligoclonal type (15.5%) (p = 0.0002). MC vasculitis (purpura, arthralgia, peripheral neuropathy, renal involvement) and other extrahepatic manifestations (polyarteritis nodosa, lymphoma) in 60/125 patients was associated with advanced age (p < 0.01), a longer duration of infection (p < 0.05), type II MC (odds ratio = 5, p < 0.01), and a higher MC serum level (p < 0.01). CONCLUSION: During chronic active HCV infection, type II MC is more stable over time than type III and oligoclonal MC. The oligoclonal type appears to be an intermediate stage in the course of type III changing to type II MC. Symptomatic persistent HCV MC was associated with advanced age, longer duration of HCV infection, type II MC, and a higher MC serum level.     

Chemokines and Antimicrobial Peptides Have a cag-Dependent Early Response to Helicobacter pylori Infection in Primary Human Gastric Epithelial Cells

Helicobacter pylori infection systematically causes chronic gastric inflammation that can persist asymptomatically or evolve toward more severe gastroduodenal pathologies, such as ulcer, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. The cag pathogenicity island (cag PAI) of H. pylori allows translocation of the virulence protein CagA and fragments of peptidoglycan into host cells, thereby inducing production of chemokines, cytokines, and antimicrobial peptides. In order to characterize the inflammatory response to H. pylori, a new experimental protocol for isolating and culturing primary human gastric epithelial cells was established using pieces of stomach from patients who had undergone sleeve gastrectomy. Isolated cells expressed markers indicating that they were mucin-secreting epithelial cells. Challenge of primary epithelial cells with H. pylori B128 underscored early dose-dependent induction of expression of mRNAs of the inflammatory mediators CXCL1 to -3, CXCL5, CXCL8, CCL20, BD2, and tumor necrosis factor alpha (TNF-α). In AGS cells, significant expression of only CXCL5 and CXCL8 was observed following infection, suggesting that these cells were less reactive than primary epithelial cells. Infection of both cellular models with H. pylori B128ΔcagM, a cag PAI mutant, resulted in weak inflammatory-mediator mRNA induction. At 24 h after infection of primary epithelial cells with H. pylori, inflammatory-mediator production was largely due to cag PAI substrate-independent virulence factors. Thus, H. pylori cag PAI substrate appears to be involved in eliciting an epithelial response during the early phases of infection. Afterwards, other virulence factors of the bacterium take over in development of the inflammatory response. Using a relevant cellular model, this study provides new information on the modulation of inflammation during H. pylori infection.     

Long‐term follow‐up and second malignancies in 487 patients with hairy cell leukaemia

A large, multicentre, retrospective survey of patients with hairy cell leukaemia (HCL) was conducted in France to determine the frequency of second malignancies and to analyse the long‐term effects of the established purine nucleoside analogues (PNAs), cladribine and pentostatin. The survey retrospectively reviewed the medical history of patients and their immediate family, clinical and biological presentation at the time of HCL diagnosis, treatment choice, response to treatment, time to relapse and cause of death. Data were collected for 487 patients with HCL. Of the patients included in the survey, 18% (88/487) had a familial history of cancers, 8% (41/487) presented with malignancies before HCL diagnosis and 10% (48/487) developed second malignancies after HCL was diagnosed. An excess incidence of second malignancies was observed, with a standardized incidence ratio (SIR) of 1·86 (95% confidence interval (CI): 1·34–2·51), with no significant difference between PNAs. For second haematological malignancies alone, the SIR was markedly increased at 5·32 (95% CI: 2·90–8·92). This study highlights the high frequency of cancers in HCL patients and their family members. The frequency of second malignancies is notably increased, particularly for haematological malignancies. The respective role of pentostatin and cladribine in the development of second malignancies is debatable.     

Early matched sibling hematopoietic cell transplantation for adult AML in first remission using an age-adapted strategy: long-term results of a prospective GOELAMS study

The LAM2001 phase 3 trial, involving 832 patients with acute myeloid leukemia (AML; median: 46 years) proposed HLA-identical sibling allograft HSCT for all patients with an identified donor. The trial compared reduced-intensity conditioning (RIC) for patients older than 50 years of age (N = 47) and myeloablative conditioning for younger patients (N = 117). BM HSCT was performed in the younger patients, while the older ones received a consolidation course, followed by peripheral blood allo-HSCT using RIC. The incidence of grade II-IV acute GVHD, was 51.9% (95% confidence interval [CI]: 42.1-61.8) and 11.3% (1.6-21.2) after myeloablative or RIC, respectively (P < .0001) and that of chronic GVHD 45.8% (95% CI: 34.8-56.7) and 41.7% (24.7-58.6; NS). Cumulative incidence of nonrelapse mortality at 108 months was 15.8% (95% CI: 9.8-23.2) for myeloablative, and 6.5% (0.2-16.2) for RIC (NS). CI of relapse at 108 months was 21.7% (95% CI: 13.9-28.6) and 28.6% (16.5-43.4; NS). Overall survival at 108 months was 63.4% (95% CI: 54.6-72.2) and 65.8% (52.2-72.2), respectively, after myeloablative or RIC (NS). RIC peripheral blood stem cell allo-HSCT is prospectively feasible for patients between the ages of 51 and 60 years without excess of relapse or nonrelapse mortality, and compares favorably with myeloablative marrow allo-HSCT proposed to younger patients.