Stochastic Expansions Maintain the Clonal Stability of CD8+ T Cell Populations Undergoing Memory Inflation Driven by Murine Cytomegalovirus.

CMV is an obligate and persistent intracellular pathogen that continually drives the production of highly differentiated virus-specific CD8+ T cells in an Ag-dependent manner, a phenomenon known as memory inflation. Extensive proliferation is required to generate and maintain inflationary CD8+ T cell populations, which are counterintuitively short-lived and typically exposed to limited amounts of Ag during the chronic phase of infection. An apparent discrepancy therefore exists between the magnitude of expansion and the requirement for ongoing immunogenic stimulation. To address this issue, we explored the clonal dynamics of memory inflation. First, we tracked congenically marked OT-I cell populations in recipient mice infected with murine CMV (MCMV) expressing the cognate Ag OVA. Irrespective of numerical dominance, stochastic expansions were observed in each population, such that dominant and subdominant OT-I cells were maintained at stable frequencies over time. Second, we characterized endogenous CD8+ T cell populations specific for two classic inflationary epitopes, M38 and IE3. Multiple clonotypes simultaneously underwent Ag-driven proliferation during latent infection with MCMV. In addition, the corresponding CD8+ T cell repertoires were stable over time and dominated by persistent clonotypes, many of which also occurred in more than one mouse. Collectively, these data suggest that stochastic encounters with Ag occur frequently enough to maintain oligoclonal populations of inflationary CD8+ T cells, despite intrinsic constraints on epitope display at individual sites of infection with MCMV.

The human Piwi protein Hiwi2 associates with tRNA-derived piRNAs in somatic cells.

The Piwi-piRNA pathway is active in animal germ cells where its functions are required for germ cell maintenance and gamete differentiation. Piwi proteins and piRNAs have been detected outside germline tissue in multiple phyla, but activity of the pathway in mammalian somatic cells has been little explored. In particular, Piwi expression has been observed in cancer cells, but nothing is known about the piRNA partners or the function of the system in these cells. We have surveyed the expression of the three human Piwi genes, Hiwi, Hili and Hiwi2, in multiple normal tissues and cancer cell lines. We find that Hiwi2 is ubiquitously expressed; in cancer cells the protein is largely restricted to the cytoplasm and is associated with translating ribosomes. Immunoprecipitation of Hiwi2 from MDAMB231 cancer cells enriches for piRNAs that are predominantly derived from processed tRNAs and expressed genes, species which can also be found in adult human testis. Our studies indicate that a Piwi-piRNA pathway is present in human somatic cells, with an uncharacterised function linked to translation. Taking this evidence together with evidence from primitive organisms, we propose that this somatic function of the pathway predates the germline functions of the pathway in modern animals.

Efficacy and safety of secukinumab in the treatment of moderate-to-severe plaque psoriasis: a randomized, double-blind, placebo-controlled phase II dose-ranging study.

BACKGROUND: Conventional systemic therapies for plaque psoriasis have not fully met the needs of patients, and although current biologic treatments are generally well tolerated, concerns exist with respect to long-term safety. Interleukin (IL)-17A is believed to be an important effector cytokine in the pathogenesis of psoriasis and is produced by Th17 cells, a class of helper T cells that act outside the established Th1/Th2 paradigm for regulation of innate and adaptive immunity. OBJECTIVES: To assess the efficacy and safety of different doses of secukinumab, a fully human anti-IL-17A IgG1κ monoclonal antibody, in patients with moderate-to-severe plaque psoriasis. METHODS: Patients (n = 125) were randomized 1 : 1 : 1 : 1 : 1 to receive subcutaneous doses of placebo (n = 22) or secukinumab [1 × 25 mg (n = 29), 3 × 25 mg (n = 26), 3 × 75 mg (n = 21) or 3 × 150 mg (n = 27)] at weeks 0, 4 and 8. After the 12-week treatment period, patients entered a follow-up period of 24 weeks. The primary efficacy outcome was at least 75% improvement from baseline in the Psoriasis Area and Severity Index score (PASI 75); secondary outcomes included the Investigator's Global Assessment (IGA) and PASI 90 and 50 response rates. RESULTS: After 12 weeks of treatment, secukinumab 3 × 150 mg and 3 × 75 mg resulted in significantly higher PASI 75 response rates vs. placebo (82% and 57% vs. 9%; P < 0·001 and P = 0·002, respectively). Higher PASI 75 response rates compared with placebo were maintained throughout the follow-up period with these dosages [week 36, 26% (n = 7) and 19% (n = 4) vs. 4% (n = 1), respectively], with a gradual decline of PASI 75 response over time after the dosing period. IGA response rates were significantly higher in the 3 × 150 mg group vs. placebo at week 12 (48% vs. 9%; P = 0·005) and were consistently higher for the 3 × 150 mg and 3 × 75 mg groups vs. placebo at all time points from week 4 onward. The PASI 90 response rate was significantly higher in the 3 × 150 mg group vs. placebo (52% vs. 5%) at week 12 and remained higher during the follow-up period. Secukinumab was well tolerated. Two cases of neutropenia (≤ grade 2) were reported in the 3 × 150 mg cohort. CONCLUSIONS: Treatment with subcutaneous secukinumab 3 × 75 mg and 3 × 150 mg met the primary outcome of PASI 75 response achievement after 12 weeks, demonstrating efficacy in moderate-to-severe psoriasis.

Early priming minimizes the age-related immune compromise of CD8⁺ T cell diversity and function.

The elderly are particularly susceptible to influenza A virus infections, with increased occurrence, disease severity and reduced vaccine efficacy attributed to declining immunity. Experimentally, the age-dependent decline in influenza-specific CD8(+) T cell responsiveness reflects both functional compromise and the emergence of 'repertoire holes' arising from the loss of low frequency clonotypes. In this study, we asked whether early priming limits the time-related attrition of immune competence. Though primary responses in aged mice were compromised, animals vaccinated at 6 weeks then challenged >20 months later had T-cell responses that were normal in magnitude. Both functional quality and the persistence of 'preferred' TCR clonotypes that expand in a characteristic immunodominance hierarchy were maintained following early priming. Similar to the early priming, vaccination at 22 months followed by challenge retained a response magnitude equivalent to young mice. However, late priming resulted in reduced TCRß diversity in comparison with vaccination earlier in life. Thus, early priming was critical to maintaining individual and population-wide TCRß diversity. In summary, early exposure leads to the long-term maintenance of memory T cells and thus preserves optimal, influenza-specific CD8(+) T-cell responsiveness and protects against the age-related attrition of naïve T-cell precursors. Our study supports development of vaccines that prime CD8(+) T-cells early in life to elicit the broadest possible spectrum of CD8(+) T-cell memory and preserve the magnitude, functionality and TCR usage of responding populations. In addition, our study provides the most comprehensive analysis of the aged (primary, secondary primed-early and secondary primed-late) TCR repertoires published to date.

The penetrance of an epigenetic trait in mice is progressively yet reversibly increased by selection and environment.

Natural selection acts on variation that is typically assumed to be genetic in origin. But epigenetic mechanisms, which are interposed between the genome and its environment, can create diversity independently of genetic variation. Epigenetic states can respond to environmental cues, and can be heritable, thus providing a means by which environmentally responsive phenotypes might be selectable independent of genotype. Here, we have tested the possibility that environment and selection can act together to increase the penetrance of an epigenetically determined phenotype. We used isogenic A(vy) mice, in which the epigenetic state of the A(vy) allele is sensitive to dietary methyl donors. By combining methyl donor supplementation with selection for a silent A(vy) allele, we progressively increased the prevalence of the associated phenotype in the population over five generations. After withdrawal of the dietary supplement, the shift persisted for one generation but was lost in subsequent generations. Our data provide the first demonstration that selection for a purely epigenetic trait can result in cumulative germline effects in mammals. These results present an alternative to the paradigm that natural selection acts only on genetic variation, and suggest that epigenetic changes could underlie rapid adaptation of species in response to natural environmental fluctuations.

Double-stranded RNA is pathogenic in Drosophila models of expanded repeat neurodegenerative diseases.

The pathogenic agent responsible for the expanded repeat diseases, a group of neurodegenerative diseases that includes Huntington's disease is not yet fully understood. Expanded polyglutamine (polyQ) is thought to be the toxic agent in certain cases, however, not all expanded repeat disease genes can encode a polyQ sequence. Since a repeat-containing RNA intermediary is common to all of these diseases, hairpin-forming single-stranded RNA has been investigated as a potential common pathogenic agent. More recently, it has become apparent that most of the expanded repeat disease loci have transcription occurring from both strands, raising the possibility that the complementary repeat RNAs could form a double-stranded structure. In our investigation using Drosophila models of these diseases, we identified a fortuitous integration event that models bidirectional repeat RNA transcription with the resultant flies exhibiting inducible pathology. We therefore established further lines of Drosophila expressing independent complementary repeat RNAs and found that these are toxic. The Dicer pathway is essential for this toxicity and in neuronal cells accounts for metabolism of the high copy number (CAG.CUG)(100) double-stranded RNAs down to (CAG)(7) single-stranded small RNAs. We also observe significant changes to the microRNA profile in neurons. These data identify a novel pathway through which double-stranded repeat RNA is toxic and capable of eliciting symptoms common to neurodegenerative human diseases resulting from dominantly inherited expanded repeats.

Engineering a waste management enzyme to overcome cancer resistance to apoptosis: adding DNase1 to the anti-cancer toolbox.

Cancer treatment is often complicated by resistance to conventional anti-cancer treatment and to more recently developed immunotherapy and gene therapy. These therapeutic modalities aim at activating death pathways within cancer cells. Attempts to activate the apoptotic death pathway, by overexpressing proapoptotic signals, are compromised by cancer defense mechanisms, which disrupt the apoptotic-signaling cascade downstream of the overexpressed component. Here, we describe a therapeutic option of triggering apoptosis without activating the apoptotic-signaling cascade or using the native apoptosis executioner nuclease. We have engineered Deoxyribonuclease-1 (DNase1), a waste-management enzyme, by deleting its signal peptide, adding a nuclear localization signal, and mutating its actin-binding site. Apoptosis studies and colony-forming assay for assessing cell viability were conducted in apoptosis-resistant Mel-Juso human melanoma cells. The modified DNase1 reduced cell viability by 77% relative to controls. It also induced typical microscopic features of cellular apoptosis, such as Terminal Transferase dUTP Nick-End Labeling-positive cells and DNA fragmentation. Quantification of apoptosis by Laser scanning cytometry demonstrated high-killing efficiency of 70-100%. The results suggest that this modified DNase1 can efficiently eliminate apoptosis-resistant cancer cells through apoptosis. Coupled to different tissue-specific gene expression elements, this recombinant DNase1 may serve as a platform for eliminating a variety of cancer types.

Efficacy and tolerability of vildagliptin in patients with type 2 diabetes inadequately controlled with metformin monotherapy.

The aim of the study was to evaluate the efficacy and safety of vildagliptin added to metformin in patients with type 2 diabetes mellitus. A multicentre, double-blind, randomized, placebo-controlled, 24-week study in patients inadequately controlled with metformin (HbA(1c) 7.5-11%) was designed. Patients were randomized to vildagliptin (Galvus) 100 mg given in the morning (AM), vildagliptin 100 mg given in the evening (PM), or placebo. The primary objective was to demonstrate that HbA(1c) reduction with once-daily vildagliptin 100 mg AM dosing is superior to placebo. Change from baseline to study endpoint in adjusted mean (SE) HbA(1c) improved significantly with vildagliptin AM dosing (-0.66 [0.11] versus 0.17% [0.11] with placebo; p <0.001). Subgroup analyses revealed that HbA(1c) reduction from baseline was greatest in those patients who had the highest baseline HbA(1c) levels. According to a predefined set of response criteria, the percentage of responder patients was significantly greater in the vildagliptin AM dosing group than in the placebo group for all responder definitions. Further analysis also revealed comparable efficacy between AM and PM dosing. Body weight remained generally stable in the combined vildagliptin group (+0.06 kg) and decreased with placebo (-0.69 kg); the incidence of adverse events was similar with vildagliptin AM dosing and placebo (30.4 and 34.4%, respectively). Vildagliptin 100 mg given as a morning dose is an effective and well-tolerated treatment option in patients with type 2 diabetes mellitus inadequately controlled with metformin monotherapy, and is equally efficacious when given as either a morning or evening dose.

Lumiracoxib 400 mg once daily is comparable to indomethacin 50 mg three times daily for the treatment of acute flares of gout.

OBJECTIVES: To demonstrate non-inferiority of lumiracoxib 400 mg once daily (o.d.) compared with indomethacin 50 mg three times daily (t.i.d.) in the treatment of acute gout, and to compare the safety and tolerability of these treatments. METHODS: In this 1-week, multicentre, randomized, double-blind, double-dummy, active-controlled, parallel-group study, patients with a clinical diagnosis of gout, an acute attack of gout in four or more joints within the 48 h prior to evaluation, and at least moderate pain intensity in the target joint were randomized to treatment with lumiracoxib 400 mg o.d. (n = 118) or indomethacin 50 mg t.i.d. (n = 117). The primary efficacy endpoint was the mean change in pain intensity from baseline over days 2-5, assessed on a 5-point Likert scale, where non-inferiority could be claimed if the lower limit of the confidence interval (CI) was greater than -0.5. The patient's and physician's global assessment of response to treatment, and physician's assessment of tenderness, swelling and erythema of the study joint were also assessed. RESULTS: The estimated difference between treatments for the change from baseline in pain intensity over days 2-5 was -0.004 (95% CI -0.207 to 0.199, P > 0.05), indicating that lumiracoxib 400 mg o.d. had comparable efficacy to indomethacin 50 mg t.i.d. for the primary efficacy variable. There was no significant difference between treatments in any of the secondary efficacy variables. Adverse events were reported by 10.2% of patients treated with lumiracoxib and 22.2% of those receiving indomethacin. CONCLUSIONS: Lumiracoxib is as effective as indomethacin for treatment of acute gout and may have a better safety and tolerability profile.

An outbreak of Escherichia coli O157 gastroenteritis in a care home for the elderly.

In the summer of 2001 an outbreak of Escherichia coli O157 gastroenteritis affected staff and residents of a care home for the elderly in the West Midlands, UK. E. coli O157 phage type 2 was isolated from faeces in eight patients and 12 staff members. Thirty-five staff and 40 residents met the case definition for clinical gastrointestinal infection. Serological testing identified a further 14 possible cases of infection amongst asymptomatic staff and residents. The outbreak was atypical, as the disease seemed to be milder than has been observed in past outbreaks in similar settings. The index case, a member of staff, developed bloody diarrhoea and haemolytic-uraemic syndrome (HUS), but only one resident developed bloody diarrhoea and required hospitalization. No deaths occurred, despite the high-risk nature of the affected population. The source of the outbreak could not be identified. The prolonged nature of the outbreak and observed lapses in infection control practices indicated that person-to-person spread was the likely route of transmission. This outbreak illustrates the importance of observing appropriate infection control measures in the institutions providing residential and nursing care to the elderly.

Differential impact of blood pressure-lowering drugs on central aortic pressure and clinical outcomes: principal results of the Conduit Artery Function Evaluation (CAFE) study.

BACKGROUND: Different blood pressure (BP)-lowering drugs could have different effects on central aortic pressures and thus cardiovascular outcome despite similar effects on brachial BP. The Conduit Artery Function Evaluation (CAFE) study, a substudy of the Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT), examined the impact of 2 different BP lowering-regimens (atenolol+/-thiazide-based versus amlodipine+/-perindopril-based therapy) on derived central aortic pressures and hemodynamics. METHODS AND RESULTS: The CAFE study recruited 2199 patients in 5 ASCOT centers. Radial artery applanation tonometry and pulse wave analysis were used to derive central aortic pressures and hemodynamic indexes on repeated visits for up to 4 years. Most patients received combination therapy throughout the study. Despite similar brachial systolic BPs between treatment groups (Delta0.7 mm Hg; 95% CI, -0.4 to 1.7; P=0.2), there were substantial reductions in central aortic pressures with the amlodipine regimen (central aortic systolic BP, Delta4.3 mm Hg; 95% CI, 3.3 to 5.4; P<0.0001; central aortic pulse pressure, Delta3.0 mm Hg; 95% CI, 2.1 to 3.9; P<0.0001). Cox proportional-hazards modeling showed that central pulse pressure was significantly associated with a post hoc-defined composite outcome of total cardiovascular events/procedures and development of renal impairment in the CAFE cohort (unadjusted, P<0.0001; adjusted for baseline variables, P<0.05). CONCLUSIONS: BP-lowering drugs can have substantially different effects on central aortic pressures and hemodynamics despite a similar impact on brachial BP. Moreover, central aortic pulse pressure may be a determinant of clinical outcomes, and differences in central aortic pressures may be a potential mechanism to explain the different clinical outcomes between the 2 BP treatment arms in ASCOT.

Telomere length in small-for-gestational-age babies.

OBJECTIVE: Short telomeres are associated with adult cardiovascular disease. Our aim was to determine whether small-for-gestational-age (SGA) newborns have shortened telomeres compared with appropriately grown controls. DESIGN: Prospective cohort study. SETTING: Large tertiary referral unit in Trent, UK. POPULATION: Seventy-two women who delivered at 35-42 weeks of gestation were recruited; 34 delivered SGA babies (less than or equal to the third birthweight centile) and 38 had appropriately grown babies (greater than the tenth centile). METHODS: Maternal and cord blood samples were collected at delivery. A Southern blot of DNA from these samples was hybridised with a 32P-labelled telomeric probe and telomere length was measured. MAIN OUTCOME MEASURES: Mean maternal and newborn telomere length. RESULTS: Maternal and newborn telomere lengths were significantly correlated in both the SGA and the control groups (r2 = 0.25, P < 0.0001). Telomere lengths were similar in both maternal (control 8.41 +/- 0.9 kb versus SGA 8.29 +/- 1.0 kb, P = 0.57) and newborn (control 10.36 +/- 1.5 kb versus SGA 10.33 +/- 1.3 kb, P = 0.93) cohorts in the two groups. CONCLUSIONS: Intrauterine events associated with impaired fetal growth do not appear to be associated with increased telomere shortening.

Reduced incidence of gastroduodenal ulcers associated with lumiracoxib compared with ibuprofen in patients with rheumatoid arthritis.

BACKGROUND: Lumiracoxib (Prexige; Novartis Pharma AG, Basel, Switzerland) is a cyclooxygenase-2 selective inhibitor associated with improved gastrointestinal safety compared with nonsteroidal anti-inflammatory drugs, in patients with osteoarthritis. AIM: To compare the gastroduodenal safety of lumiracoxib with ibuprofen and celecoxib in patients with rheumatoid arthritis. METHODS: A total of 893 patients with rheumatoid arthritis were randomized to lumiracoxib 400 mg once daily, lumiracoxib 800 mg once daily, ibuprofen 800 mg three times daily or celecoxib 200 mg twice daily for 13 weeks, in a double-blind randomised controlled clinical trial. The primary endpoint was the cumulative incidence of gastroduodenal ulcers over 13 weeks. RESULTS: The incidence of gastroduodenal ulcers >/=3 mm with lumiracoxib 400 mg once daily (2.8%) or lumiracoxib 800 mg once daily (4.3%) was significantly lower than with ibuprofen (13.6%, all P < 0.01) and not different from celecoxib (1.9%). The incidence of adverse events was similar for lumiracoxib 400, 800 mg and celecoxib (78, 75 and 77%, respectively) and higher with ibuprofen (86%). Discontinuation for adverse events was highest for ibuprofen (12.5% vs. 7.9-8.8% for the other groups). CONCLUSIONS: Lumiracoxib demonstrated gastroduodenal safety superior to ibuprofen and similar to celecoxib in patients with rheumatoid arthritis.

Tropical plant pathology: at home and abroad.

I first describe my introduction to plant pathology and early experiences with employment, the environment, diseases, pests, and various plant pathologists. Then I recount a decade of stimulating studies at the University of Minnesota and the route I followed to a career in international agriculture with the Rockefeller Foundation in Colombia and later at Cornell University. My appreciation for and knowledge of traditional farmers and sustainable agriculture occurred as a slow awakening. Comments are made regarding problems, principles, and satisfactions associated with the improvement of efforts to aid food production in developing countries. My curious love affair with root and tuber crops, especially cassava, is explained and readily defended. My favorite pathogens, Phytophthora infestans and Ralstonia solanacearum, among others, are considered. The pleasures and satisfactions of teaching, writing, and sabbatical leaves are related. Finally, thoughts on the balance between basic and applied research in plant pathology are offered with significant nervousness about the future of our discipline.

Evidence against potassium as an endothelium-derived hyperpolarizing factor in rat mesenteric small arteries.

1. Endothelium-derived hyperpolarizing factor (EDHF) has recently been identified as potassium released from endothelial cells into the myo-endothelial space. The present study was designed to test this hypothesis. 2. In rat small mesenteric arteries, mounted in a wire myograph, relaxation to acetylcholine or potassium was not significantly changed following incubation with oxadiazolo-quinoxalin-1-one (ODQ, 4 microM) and indomethacin (10 microM, n = 9). 3. Maximal relaxations to acetylcholine occurred in all arteries, were maintained and were significantly greater (P < 0.01, n = 9) than the transient relaxations to potassium, which only occurred in 30-40% of vessels. 4. Removal of the vascular endothelium abolished relaxant responses both to potassium and acetylcholine (P < 0.005, n = 9). 5. Compared with responses in 5.5 mM potassium PSS, relaxation responses to added potassium in arteries maintained in 1.5 mM potassium PSS were more marked and were not dependent on the presence of an intact endothelium (n = 8). 6. Incubation with BaCl2 (50 microM) significantly inhibited the maximal relaxant response to potassium in the presence of an intact endothelium in 5.5 mM potassium PSS (P < 0.05, n = 4), but had no effect on relaxation of de-endothelialized preparations in 1.5 mM potassium PSS (n = 5). 7. Treatment with ouabain (0.1 mM) abolished the relaxant response to potassium in 1.5 mM potassium PSS (P < 0.001, n = 9), but only partly inhibited the maximal relaxant response to acetylcholine in 5.5 mM potassium PSS (P < 0.01, n = 5). 8. These data show that at physiological concentrations of potassium an intact endothelium is necessary for potassium-induced relaxation in rat mesenteric arteries. Furthermore, the response to potassium is clearly different to that from acetylcholine, indicating that potassium does not mimic EDHF released by acetylcholine in these arteries.

Altered small artery morphology and reactivity in critical limb ischaemia.

Although the pathophysiology of critical limb ischaemia is poorly understood, there is evidence that the condition of the small arteries may determine the outcome of revascularization procedures. This study was designed to investigate the effects of critical limb ischaemia on the structure and function of the small arteries in the leg. Small arteries (<500 microm) from proximal (non-ischaemic) and distal (ischaemic) sites were obtained from patients undergoing bypass surgery for critical limb ischaemia and mounted in a myograph. Reactivity and morphological measurements were carried out and compared with controls. Control vessels from the thigh and calf showed no difference in media to lumen ratio. However, a comparison of ischaemic and non-ischaemic vessels from the patients with critical limb ischaemia showed significant thinning of the ischaemic vessel wall. Contraction studies using noradrenaline and angiotensin II revealed a significant decrease in the response of ischaemic vessels compared with the non-ischaemic vessels from the same patient. Moreover, these differences in reactivity were still apparent after the responses were corrected for wall thickness. Endothelial function assessed using the endothelium-dependent agonists acetylcholine and bradykinin showed a significantly impaired relaxation response to acetylcholine but not to bradykinin in the ischaemic vessels, and acetylcholine-induced relaxation was not improved after incubation with indomethacin. There was no change in the response to the endothelium-independent cAMP-mediated vasodilator iloprost but a significant impairment to sodium nitroprusside which acts via cGMP. These results suggest that small arteries in critical limb ischaemia are altered in both structure and function, with vessel wall thinning and impaired responses to acetylcholine and sodium nitroprusside.