Transmissions to mice indicate that 'new variant' CJD is caused by the BSE agent

There are many strains of the agents that cause transmissible spongiform encephalopathies (TSEs) or 'prion' diseases. These strains are distinguishable by their disease characteristics in experimentally infected animals, in particular the incubation periods and neuropathology they produce in panels of inbred mouse strains. We have shown that the strain of agent from cattle affected by bovine spongiform encephalopathy (BSE) produces a characteristic pattern of disease in mice that is retained after experimental passage through a variety of intermediate species. This BSE 'signature' has also been identified in transmissions to mice of TSEs of domestic cats and two exotic species of ruminant, providing the first direct evidence for the accidental spread of a TSE between species. Twenty cases of a clinically and pathologically atypical form of Creutzfeldt-Jakob disease (CJD), referred to as 'new variant' CJD (vCJD), have been recognized in unusually young people in the United Kingdom, and a further case has been reported in France. This has raised serious concerns that BSE may have spread to humans, putatively by dietary exposure. Here we report the interim results of transmissions of sporadic CJD and vCJD to mice. Our data provide strong evidence that the same agent strain is involved in both BSE and vCJD.

The prevalence of hypertension in seven populations of west African origin

OBJECTIVES

This study was undertaken to describe the distribution of blood pressures, hypertension prevalence, and associated risk factors among seven populations of West African origin.

METHODS

The rates of hypertension in West Africa (Nigeria and Cameroon), the Caribbean (Jamaica, St. Lucia, Barbados), and the United States (metropolitan Chicago, Illinois) were compared on the basis of a highly standardized collaborative protocol. After researchers were given central training in survey methods, population-based samples of 800 to 2500 adults over the age of 25 were examined in seven sites, yielding a total sample of 10014.

RESULTS

A consistent gradient of hypertension prevalence was observed, rising from 16% in West Africa to 26% in the Caribbean and 33% in the United States. Mean blood pressures were similar among persons aged 25 to 34, while the increase in hypertension prevalence with age was twice as steep in the United States as in Africa. Environmental factors, most notably obesity and the intake of sodium and potassium, varied consistently with disease prevalence across regions.

CONCLUSION

The findings demonstrate the determining role of social conditions in the evolution of hypertension risk in these populations.

Transmission of bovine spongiform encephalopathy and scrapie to mice: strain variation and the species barrier

Transmissions of bovine spongiform encephalopathy (BSE) from seven unrelated cattle sources have given remarkably uniform disease characteristics in mice, differing from over twenty previous and contemporary transmissions of sheep and goat scrapie. Transmissions to mice of spongiform encephalopathy from six species (including sheep and goats) which have been experimentally or naturally infected with BSE have given similar results to direct BSE transmissions from cattle. Therefore the BSE agent has retained its identity when passaged through a range of species and the 'donor' species has little specific influence on disease characteristics in mice, adding to evidence for an agent-specific informational molecule. On transmission of BSE or scrapie to mice the incubation periods are long compared with subsequent mouse-to-mouse passages (the 'species barrier'). Contributing factors include a low efficiency of infection on interspecies transmission, the apparent failure of intracerebrally injected 'foreign' inoculum to establish infection directly in mouse brain and the selection of variant strains of agent which replicate most readily in the new host species.

The disease characteristics of different strains of scrapie in Sinc congenic mouse lines: implications for the nature of the agent and host control of pathogenesis

Mouse lines which are congenic for Sinc, the major gene controlling scrapie incubation period, have been produced by selective breeding from the inbred C57BL(Sincs7) and VM(Sincp7) strains; the s7 allele of Sinc has been introduced into a VM background by 18 serial backcrosses, at each generation selecting on the basis of the incubation period with the ME7 scrapie strain. The characteristics of the disease produced by seven scrapie strains have been compared in Sincs7 and Sincp7 congenic mice and in the F1 cross between them. As previously found in non-congenic mice, each scrapie strain has a characteristic, precisely reproducible incubation period pattern in the three Sinc genotypes. The Sinc gene controls the incubation period for all scrapie strains tested but the direction of allelic action and the apparent dominance pattern differs between scrapie strains. Comparison with non-congenic mice shows that other genes also have a minor effect on incubation period. The distribution of vacuolar degeneration in the brain depends mainly on the scrapie strain but is also influenced by Sinc and other unspecified mouse genes. Restriction fragment length polymorphism analysis has already shown that the close linkage between Sinc and the gene encoding PrP has been maintained in the Sinc congenic lines, strengthening the possibility that PrP is the Sinc gene product. The present study confirms that scrapie strains carry information which is independent of the host but nevertheless suggests that host PrP protein interacts with this information to regulate the progression of the disease.

Scrapie replication in lymphoid tissues depends on prion protein-expressing follicular dendritic cells

The immune system is central in the pathogenesis of scrapie and other transmissible spongiform encephalopathies (TSEs) or 'prion' diseases. After infecting by peripheral (intraperitoneal or oral) routes, most TSE agents replicate in spleen and lymph nodes before neuroinvasion. Characterization of the cells supporting replication in these tissues is essential to understanding early pathogenesis and may indicate potential targets for therapy, for example, in 'new variant' Creutzfeldt-Jakob disease. The host 'prion' protein (PrP) is required for TSE agent replication and accumulates in modified forms in infected tissues. Abnormal PrP is detected readily on follicular dendritic cells (FDCs) in lymphoid tissues of patients with 'new variant' Creutzfeldt-Jakob disease, sheep with natural scrapie and mice experimentally infected with scrapie. The normal protein is present on FDCs in uninfected mice and, at lower levels, on lymphocytes. Studies using severe combined immunodeficiency (SCID) mice, with and without bone marrow (BM) grafts, have indicated involvement of FDCs and/or lymphocytes in scrapie pathogenesis. To clarify the separate roles of FDCs and lymphocytes, we produced chimeric mice with a mismatch in PrP status between FDCs and other cells of the immune system, by grafting bone marrow from PrP-deficient knockout mice into PrP-expressing mice and vice versa. Using these chimeric models, we obtained strong evidence that FDCs themselves produce PrP and that replication of a mouse-passaged scrapie strain in spleen depends on PrP-expressing FDCs rather than on lymphocytes or other bone marrow-derived cells.

N-WASP deficiency reveals distinct pathways for cell surface projections and microbial actin-based motility

The Wiskott-Aldrich syndrome protein (WASP) family of molecules integrates upstream signalling events with changes in the actin cytoskeleton. N-WASP has been implicated both in the formation of cell-surface projections (filopodia) required for cell movement and in the actin-based motility of intracellular pathogens. To examine N-WASP function we have used homologous recombination to inactivate the gene encoding murine N-WASP. Whereas N-WASP-deficient embryos survive beyond gastrulation and initiate organogenesis, they have marked developmental delay and die before embryonic day 12. N-WASP is not required for the actin-based movement of the intracellular pathogen Listeria but is absolutely required for the motility of Shigella and vaccinia virus. Despite these distinct defects in bacterial and viral motility, N-WASP-deficient fibroblasts spread by using lamellipodia and can protrude filopodia. These results imply a crucial and non-redundant role for N-WASP in murine embryogenesis and in the actin-based motility of certain pathogens but not in the general formation of actin-containing structures.

Transmission of bovine spongiform encephalopathy to sheep and goats

Spongiform encephalopathy has been confirmed in both 'positive' and 'negative' lines of Cheviot sheep (selected for their differential response on experimental exposure to scrapie) after intracerebral injection or oral dosing with brain homogenate derived from cattle with bovine spongiform encephalopathy (BSE). With either challenge the incubation period of the disease ranged from 440 to 994 days in both lines of sheep. In a similar experiment, three Anglo-Nubian goats developed the disease 506 to 570 days after intracerebral infection with the same BSE homogenate, and two of three goats developed the disease 941 and 1501 days after oral dosing; the other goat and some sheep from each of the experimental groups remain alive 1720 days after exposure. This is the first report of the experimental transmission of BSE to sheep and goats.

Inhibition of the late sodium current as a potential cardioprotective principle: effects of the late sodium current inhibitor ranolazine

Pathological conditions linked to imbalances in oxygen supply and demand (for example, ischaemia, hypoxia and heart failure) are associated with disruptions in intracellular sodium ([Na(+)](i)) and calcium ([Ca(2+)](i)) concentration homeostasis of myocardial cells. A decreased efflux or increased influx of sodium may cause cellular sodium overload. Sodium overload is followed by an increased influx of calcium through sodium-calcium exchange. Failure to maintain the homeostasis of [Na(+)](i) and [Ca(2+)](i) leads to electrical instability (arrhythmias), mechanical dysfunction (reduced contractility and increased diastolic tension) and mitochondrial dysfunction. These events increase ATP hydrolysis and decrease ATP formation and, if left uncorrected, they cause cell injury and death. The relative contributions of various pathways (sodium channels, exchangers and transporters) to the rise in [Na(+)](i) remain a matter of debate. Nevertheless, both the sodium-hydrogen exchanger and abnormal sodium channel conductance (that is, increased late sodium current (I(Na))) are likely to contribute to the rise in [Na(+)](i). The focus of this review is on the role of the late (sustained/persistent) I(Na) in the ionic disturbances associated with ischaemia/hypoxia and heart failure, the consequences of these ionic disturbances, and the cardioprotective effects of the antianginal and anti-ischaemic drug ranolazine. Ranolazine selectively inhibits late I(Na), reduces [Na(+)](i)-dependent calcium overload and attenuates the abnormalities of ventricular repolarisation and contractility that are associated with ischaemia/reperfusion and heart failure. Thus, inhibition of late I(Na) can reduce [Na(+)](i)-dependent calcium overload and its detrimental effects on myocardial function.

PrP protein is associated with follicular dendritic cells of spleens and lymph nodes in uninfected and scrapie-infected mice

Abnormal forms of a host protein, PrP, accumulate in the central nervous system in scrapie-affected animals. Here, PrP protein was detected immunocytochemically in tissue sections of spleen, lymph node, Peyer's patches, thymus, and pancreas from uninfected mice and from mice infected with a range of mouse-passaged scrapie strains and bovine spongiform encephalopathy (BSE). In the spleen, lymph node and Peyer's patches, PrP-positive cells were identified as follicular dendritic cells (FDC) by their location, appearance, and immune complex trapping function, whereas in the thymus they appeared to be two types of stromal cells: interdigitating cells (IDC) and cortical epithelial cells. In pancreas, PrP-containing cells were confined to the islets of Langerhans. Although the distribution of PrP immunolabelling was the same in tissues from scrapie-affected and uninfected mice, there was evidence that PrP accumulated in abnormal forms in FDC of infected mice. If, as is likely, PrP is essential for agent replication, our results suggest that FDC are the site of scrapie and BSE replication in the spleen and lymph node.

Phenotypic differentiation of Streptococcus intermedius, Streptococcus constellatus, and Streptococcus anginosus strains within the "Streptococcus milleri group"

A biochemical scheme was developed by which strains of Streptococcus constellatus, Streptococcus intermedius, and Streptococcus anginosus can reliably be distinguished from within the "Streptococcus milleri group." Strains identified as S. intermedius were differentiated by the ability to produce detectable levels of alpha-glucosidase, beta-galactosidase, beta-D-fucosidase, beta-N-acetylgalactosaminidase, beta-N-acetylglucosaminidase, and sialidase with 4-methylumbelliferyl-linked fluorogenic substrates in microdilution trays after 3 h of incubation at 37 degrees C, together with the production of hyaluronidase. Strains of S. constellatus and S. anginosus were differentiated by the production of alpha-glucosidase and hyaluronidase by the former and the production of beta-glucosidase by the latter. The majority of strains of the S. milleri group obtained from dental plaque were identified as S. intermedius, as were most strains isolated from abscesses of the brain and liver. Strains of S. constellatus and S. anginosus were from a wider variety of infections, both oral and nonoral, than were strains of S. intermedius, with the majority of strains from urogenital infections being identified as S. anginosus.

The genomic identity of different strains of mouse scrapie is expressed in hamsters and preserved on reisolation in mice

263K is the most widely used strain of agent in scrapie research because it produces very short incubation periods in golden hamsters and exceptionally high infectivity titres in clinically affected brain. 263K is also remarkable in having a very low pathogenicity for mice. Evidence is presented that 263K originated as a mutant that was strongly selected on passage in hamsters. Seven new passage lines have been established in hamsters using well characterized strains of mouse scrapie representing the 'drowsy goat' and SSBP/1 families of scrapie strains, and one natural scrapie source. Considerable differences between scrapie strains were found in hamsters using incubation period criteria alone. There was evidence that the parent strain of 263K might be 79V or a strain like it in the 'drowsy goat' family. Four of the hamster passage lines were established from scrapie strains that had been cloned in mice. Reisolates in mice were compared with original strains. By the criteria used, two of the reisolates were the same as the original strains. Two others were mutants with incubation periods longer than those of their parental strains but the mutants were different from one another. It is concluded that passage between mice and hamsters can select mutants that would otherwise be lost but there is also clear evidence that the genotypic identity of some scrapie strains is preserved on passage between different host species. These findings are important in the search for the putative nucleic acid genome of the scrapie agent.

Transmission of bovine spongiform encephalopathy and scrapie to mice

Transmission from four cases of bovine spongiform encephalopathy (BSE) to mice resulted in neurological disease in 100% of recipient animals, after incubation periods of between 265 and 700 days post-injection. The results from the four cases were very similar to one another. There were major differences in the incubation period between the four inbred strains of mice tested, and even between strains of the same Sinc genotype, and the incubation periods of Sinc heterozygote mice were much longer than those for any of the inbred strains. Transmission from a case of natural scrapie differed in two important respects: there were no differences in the incubation period between mouse strains of the same Sinc genotype, and that of the heterozygotes was between those of the Sinc homozygotic parental strains. The distribution of vacuolar degeneration in the brains of mice infected with scrapie also differed from those infected with the BSE isolates. Transmission was also achieved from formol-fixed BSE brain. These results show that the same strain of agent caused disease in the BSE cases, and that the relationship of BSE to scrapie in sheep is unclear.

Decontamination studies with the agents of bovine spongiform encephalopathy and scrapie

Macerates of bovine brain infected with bovine spongiform encephalopathy (BSE) agent, and rodent brain infected with the 263K or ME7 strains of scrapie agent, were subjected to porous-load autoclaving at temperatures between 134 and 138 degrees C for < or = 60 min. Bioassay in rodents showed that none of the regimens produced complete inactivation. Homogenates of BSE-infected bovine brain were exposed for < or = 120 min to solutions of sodium hypochlorite or sodium dichloroisocyanurate containing < or = 16,500 ppm available chlorine. There was no detectable survival of infectivity after the hypochlorite treatments but none of the dichloroisocyanurate solutions produced complete inactivation. Homogenates of BSE-infected bovine brain, and rodent brain infected with the 263K and ME7 strains of scrapie agent, were exposed for < or = 120 min to 1M or 2M sodium hydroxide but no procedure produced complete inactivation of all agents tested.

Focal modification of electrical conduction in the heart by viral gene transfer

Modern treatment of cardiac arrhythmias is limited to pharmacotherapy, radiofrequency ablation, or implantable devices. Antiarrhythmic medications suppress arrhythmias, but their systemic effects are often poorly tolerated and their proarrhythmic tendencies increase mortality. Radiofrequency ablation can cure only a limited number of arrhythmias. Implantable devices can be curative for bradyarrhythmias and lifesaving for tachyarrhythmias, but require a lifetime commitment to repeated procedures, are a significant expense, and may lead to severe complications. One possibility is the use of gene therapy as an antiarrhythmic strategy. As an initial attempt to explore this option, we focused on genetic modification of the atrioventricular node. First, we developed an intracoronary perfusion model for gene delivery, building on our previous work in isolated cardiac myocytes and hearts perfused ex vivo. Using this method, we infected porcine hearts with Adbetagal (recombinant adenovirus expressing Escherichia coli beta-galactosidase) or with AdGi (adenovirus encoding the Galphai2 subunit). We hypothesized that excess Galphai2 would mimic the effects of beta-adreneric antagonists, in effect creating a localized beta-blockade. Galphai2 overexpression suppressed baseline atrioventricular conduction and slowed the heart rate during atrial fibrillation without producing complete heart block. In contrast, expression of the reporter gene beta-galactosidase had no electrophysiological effects. Our results demonstrate the feasibility of using myocardial gene transfer strategies to treat common arrhythmias.

Prevalence of NIDDM among populations of the African diaspora

OBJECTIVE

Rates of non-insulin-dependent diabetes mellitus have risen sharply in recent years among blacks in the U.S. and the U.K. Increases in risk have likewise been observed in the island nations of the Caribbean and in urban West Africa. To date, however, no systematic comparison of the geographic variation of NIDDM among black populations has been undertaken.

RESEARCH DESIGN AND METHODS

In the course of an international collaborative study on cardiovascular disease, we used a standardized protocol to determine the rates of NIDDM and associated risk factors in populations of the African diaspora. Representative samples were drawn from sites in Nigeria, St. Lucia, Barbados, Jamaica, the United States, and the United Kingdom. A total of 4,823 individuals aged 25-74 years were recruited, all sites combined.

RESULTS

In sharp contrast to a prevalence of 2% in Nigeria, age-adjusted prevalences of self-reported NIDDM were 9% in the Caribbean and 11% in the U.S. and the U.K. Mean BMI ranged from 22 kg/m2 among men in West Africa to 31 kg/m2 in women in the U.S. Disease prevalence across sites was essentially collinear with obesity, pointing to site differences in the balance between energy intake and expenditure as the primary determinant of differential NIDDM risk among these populations.

CONCLUSIONS

In ethnic groups sharing a common genetic ancestry, these comparative data demonstrate the determining influence of changes in living conditions on the population risk of NIDDM.

Successful expansion of functional and stable regulatory T cells for immunotherapy in liver transplantation

Strategies to prevent organ transplant rejection whilst minimizing long-term immunosuppression are currently under intense investigation with regulatory T cells (Tregs) nearing clinical application. The clinical trial, ThRIL, recently commenced at King's College London, proposes to use Treg cell therapy to induce tolerance in liver transplant recipients, the success of which has the potential to revolutionize the management of these patients and enable a future of drug-free transplants. This is the first report of the manufacture of clinical grade Tregs from prospective liver transplant recipients via a CliniMACS-based GMP isolation technique and expanded using anti-CD3/CD28 beads, IL-2 and rapamycin. We report the enrichment of a pure, stable population of Tregs (>95% CD4(+)CD25(+)FOXP3(+)), reaching adequate numbers for their clinical application. Our protocol proved successful in, influencing the expansion of superior functional Tregs, as compared to freshly isolated cells, whilst also preventing their conversion to Th17 cells under pro-inflammatory conditions. We conclude with the manufacture of the final Treg product in the clinical research facility (CRF), a prerequisite for the clinical application of these cells. The data presented in this manuscript together with the much-anticipated clinical results from ThRIL, will undoubtedly inform the improved management of the liver transplant recipient.

Characterization of the microglial response in murine scrapie

The nature of the glial and inflammatory cell responses to infection in scrapie-affected brains was studied in terminally-affected mice of five scrapie models. There were marked astrocytic and microglial responses. Microglia showed increased staining of the surface antigens F4/80, leucocyte-common antigen, type 3 complement receptor, and elevated endocytotic and lysosomal activity. In all models, the astrocytic and microglial responses were largely restricted to anatomical regions of the brain showing vacuolation and/or plaque formation and pathological accumulations of PrP. Expression of MHC Class II was patchy and present on microglia in the neuropil of areas with the most intense microglial activation and on occasional perivascular macrophages. This microglial response may represent a modified form of inflammatory response.

Immunocytochemical appearance of cytokines, prostaglandin E2 and lipocortin-1 in the CNS during the incubation period of murine scrapie correlates with progressive PrP accumulations

The appearance of immunoreactive interleukin (IL)-1beta, IL-6 and tumour necrosis factor (TNF)-alpha, prostaglandin (PG) E2 and lipocortin-1 in the central nervous system was investigated during the development of lesions in a 301V/VM murine scrapie model. Focal PrP(Sc) deposition was present after 30 days of the 115-120 day incubation period; this immunoreactivity increased in intensity and distribution thereafter. Staining for IL-1beta and TNF alpha in perivascular macrophages, and PGE2 immunoreactivity in astrocytes, was detected in those areas showing PrP(Sc) deposition from 60 days. Increased GFAP and F4/80 immunoreactivity, indicating activation of astrocytes and microglia, was also evident in these areas from 60 days. Glial cytokine and lipocortin immunoreactivity was detected after 90 days, in the absence of clinical signs. The disease-induced cytokine, PG and lipocortin immunoreactivity occurred only in those brain areas showing PrP(Sc) deposition, glial activation and, in later stages, vacuolation. These findings support the concept that PrP(Sc) deposition induces glial cytokine production. These glial cytokines may contribute to the development of the pathological lesions in scrapie.

Infectious etiology of neuritic (senile) plaques in mice

Brains of inbred female VM mice infected with scrapie agent were studied with the use of the Bodian silver impregnation method and by electron microscopy. In brains affected with scrapie, after an incubation period of between 587 and 655 days, numerous primitive, classical, and amyloid plaques were found. No plaques of any type were seen in the control mice.

A Rapamycin-Based GMP-Compatible Process for the Isolation and Expansion of Regulatory T Cells for Clinical Trials

The concept of regulatory T cell (Treg)-based immunotherapy has enormous potential for facilitating tolerance in autoimmunity and transplantation. Clinical translation of Treg cell therapy requires production processes that satisfy the rigors of Good Manufacturing Practice (GMP) standards. In this regard, we report our findings on the implementation of a robust GMP compliant process for the ex vivo expansion of clinical grade Tregs, demonstrating the feasibility of this developed process for the manufacture of a final product for clinical application. This Treg isolation procedure ensured the selection of a pure Treg population that underwent a 300-fold expansion after 36 days of culture, while maintaining a purity of more than 75% CD4⁺CD25⁺FOXP3⁺ cells and a suppressive function of above 80%. Furthermore, we report the successful cryopreservation of the final product, demonstrating the maintenance of phenotype and function. The process outlined in this manuscript has been implemented in the ONE study, a multicenter phase I/IIa clinical trial in which cellular therapy is investigated in renal transplantation.