Continuous turnover of intracellular components by autophagy is necessary to preserve cellular homeostasis in all tissues. Alterations in macroautophagy, the main process responsible for bulk ...autophagic degradation, have been proposed to contribute to pathogenesis in Huntington's disease (HD), a genetic neurodegenerative disorder caused by an expanded polyglutamine tract in the huntingtin protein. However, the precise mechanism behind macroautophagy malfunction in HD is poorly understood. In this work, using cellular and mouse models of HD and cells from humans with HD, we have identified a primary defect in the ability of autophagic vacuoles to recognize cytosolic cargo in HD cells. Autophagic vacuoles form at normal or even enhanced rates in HD cells and are adequately eliminated by lysosomes, but they fail to efficiently trap cytosolic cargo in their lumen. We propose that inefficient engulfment of cytosolic components by autophagosomes is responsible for their slower turnover, functional decay and accumulation inside HD cells.
The most striking morphologic change in neurons during normal aging is the accumulation of autophagic vacuoles filled with lipofuscin or neuromelanin pigments. These organelles are similar to those ...containing the ceroid pigments associated with neurologic disorders, particularly in diseases caused by lysosomal dysfunction. The pigments arise from incompletely degraded proteins and lipids principally derived from the breakdown of mitochondria or products of oxidized catecholamines. Pigmented autophagic vacuoles may eventually occupy a major portion of the neuronal cell body volume because of resistance of the pigments to lysosomal degradation and/or inadequate fusion of the vacuoles with lysosomes. Although the formation of autophagic vacuoles via macroautophagy protects the neuron from cellular stress, accumulation of pigmented autophagic vacuoles may eventually interfere with normal degradative pathways and endocytic/secretory tasks such as appropriate response to growth factors.
Axon degeneration is a hallmark of neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Such degeneration is not a passive event but rather an active process mediated by ...mechanisms that are distinct from the canonical pathways of programmed cell death that mediate destruction of the cell soma. Little is known of the diverse mechanisms involved, particularly those of retrograde axon degeneration. We have previously observed in living animal models of degeneration in the nigrostriatal projection that a constitutively active form of the kinase, myristoylated Akt (Myr-Akt), demonstrates an ability to suppress programmed cell death and preserve the soma of dopamine neurons. Here, we show in both neurotoxin and physical injury (axotomy) models that Myr-Akt is also able to preserve dopaminergic axons due to suppression of acute retrograde axon degeneration. This cellular phenotype is associated with increased mammalian target of rapamycin (mTor) activity and can be recapitulated by a constitutively active form of the small GTPase Rheb, an upstream activator of mTor. Axon degeneration in these models is accompanied by the occurrence of macroautophagy, which is suppressed by Myr-Akt. Conditional deletion of the essential autophagy mediator Atg7 in adult mice also achieves striking axon protection in these acute models of retrograde degeneration. The protection afforded by both Myr-Akt and Atg7 deletion is robust and lasting, because it is still observed as protection of both axons and dopaminergic striatal innervation weeks after injury. We conclude that acute retrograde axon degeneration is regulated by Akt/Rheb/mTor signaling pathways.
Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to reduce pain and inflammation, and are considered the cornerstone of pharmacological intervention in patients with radiographic axial ...spondyloarthritis (r-axSpA); however, the long-term use of NSAIDs is debatable due to their restricted therapeutic potential and the risk of side effects and complications. Therefore, reduction in NSAID intake is desirable in r-axSpA patients. Here, we report the long-term NSAID-sparing effect of secukinumab over 4 years in patients with r-axSpA. This post hoc analysis pooled data from 3 secukinumab trials (MEASURE 2–4) for each secukinumab maintenance dose of 150 and 300 mg, regardless of the loading dose regimen being i.v. or s.c. NSAID intake was evaluated prospectively using the Assessment of SpondyloArthritis International Society (ASAS)-NSAID score. Patients with an ASAS-NSAID score > 0 at baseline were analysed. NSAID-sparing endpoints included the mean change in the ASAS-NSAID score, the proportion of patients achieving 50% reduction, and the proportion of patients with an ASAS-NSAID score < 10. Percentages of patients who achieved BASDAI ≤ 2 were also assessed. Overall, 562 patients were included in this pooled analysis (secukinumab: 150 mg,
N
= 467; 300 mg,
N
= 95). The mean ASAS-NSAID score decreased with time in both the secukinumab 150 mg and 300 mg dose groups. The proportion of patients who achieved 50% reduction in the ASAS-NSAID score and clinically meaningful reduction of ASAS-NSAID score < 10 increased with time in both dose groups and in both low and high NSAID intake patients. The percentage of patients with a clinically relevant improvement (BASDAI ≤ 2) was consistently higher in patients with an ASAS-NSAID score < 10 than in patients with an ASAS-NSAID score ≥ 10. Secukinumab provided sustained, long-term NSAID-sparing effects in patients with r-axSpA for up to 4 years of treatment, as measured using the ASAS-NSAID score. Trial registered at clinicaltrials.gov: NCT01649375 (
https://clinicaltrials.gov/ct2/show/NCT01649375
); NCT02008916 (
https://clinicaltrials.gov/ct2/show/NCT02008916
); NCT02159053 (
https://clinicaltrials.gov/ct2/show/NCT02159053
).
To present the long-term (4-year) efficacy and safety of secukinumab in Taiwanese patients with active AS in the MEASURE 1 extension study.
This
analysis reports data from Taiwanese patients ...originally randomized to subcutaneous secukinumab 150 or 75mg or placebo every 4 weeks (following intravenous loading dose) who were invited to enter the 3-year extension study. Assessments at Week 208 included ASAS20/40 responses and other clinically relevant endpoints. Efficacy data are presented as observed. Safety analyses included all patients who received ≥1 dose of secukinumab.
Of the 57 Taiwanese patients in the core trial, 48 entered the extension study and 87.5% patients (42/48) completed 4 years of treatment. Thirteen Taiwanese patients (including placebo-switchers) were escalated from 75 to 150mg (approved dose) at some point starting from Week 172. ASAS20/40 responses were sustained through 4 years in the Taiwanese patients who were originally randomized to secukinumab 150mg. Clinical responses were improved in those patients who received dose-escalation from 75 to 150mg during the study. No unexpected safety signals were reported.
Secukinumab 150mg demonstrated sustained efficacy over 4 years in Taiwanese patients with active ankylosing spondylitis. The safety profile of secukinumab was consistent with previous reports.
NCT01863732.
Autophagy functions in antiviral immunity. However, the ability of endogenous autophagy genes to protect against viral disease in vertebrates remains to be causally established. Here, we report that ...the autophagy gene Atg5 function is critical for protection against lethal Sindbis virus (SIN) infection of the mouse central nervous system. Inactivating Atg5 in SIN-infected neurons results in delayed clearance of viral proteins, increased accumulation of the cellular p62 adaptor protein, and increased cell death in neurons, but the levels of viral replication remain unaltered. In vitro, p62 interacts with SIN capsid protein, and genetic knockdown of p62 blocks the targeting of viral capsid to autophagosomes. Moreover, p62 or autophagy gene knockdown increases viral capsid accumulation and accelerates virus-induced cell death without affecting virus replication. These results suggest a function for autophagy in mammalian antiviral defense: a cell-autonomous mechanism in which p62 adaptor-mediated autophagic viral protein clearance promotes cell survival.
Both dauer formation (a stage of developmental arrest) and adult life-span in Caenorhabditis elegans are negatively regulated by insulin-like signaling, but little is known about cellular pathways ...that mediate these processes. Autophagy, through the sequestration and delivery of cargo to the lysosomes, is the major route for degrading long-lived proteins and cytoplasmic organelles in eukaryotic cells. Using nematodes with a loss-of-function mutation in the insulin-like signaling pathway, we show that bec-1, the C. elegans ortholog of the yeast and mammalian autophagy gene APG6/VPS30/beclin1, is essential for normal dauer morphogenesis and life-span extension. Dauer formation is associated with increased autophagy and also requires C. elegans orthologs of the yeast autophagy genes APG1, APG7, APG8, and AUT10. Thus, autophagy is a cellular pathway essential for dauer development and life-span extension in C. elegans.
The plant innate immune response includes the hypersensitive response (HR), a form of programmed cell death (PCD). PCD must be restricted to infection sites to prevent the HR from playing a ...pathologic rather than protective role. Here we show that plant BECLIN 1, an ortholog of the yeast and mammalian autophagy gene ATG6/VPS30/beclin 1, functions to restrict HR PCD to infection sites. Initiation of HR PCD is normal in BECLIN 1-deficient plants, but remarkably, healthy uninfected tissue adjacent to HR lesions and leaves distal to the inoculated leaf undergo unrestricted PCD. In the HR PCD response, autophagy is induced in both pathogen-infected cells and distal uninfected cells; this is reduced in BECLIN 1-deficient plants. The restriction of HR PCD also requires orthologs of other autophagy-related genes including PI3K/VPS34, ATG3, and ATG7. Thus, the evolutionarily conserved autophagy pathway plays an essential role in plant innate immunity and negatively regulates PCD.
Abstract
Objective
To evaluate the effect of secukinumab, a fully human anti-interleukin-17A monoclonal antibody, on efficacy, imaging outcomes, and safety through 4 years (208 weeks) in patients ...with ankylosing spondylitis.
Methods
Patients opting to enrol had completed 2 years' treatment in the MEASURE 1 core study with subcutaneous secukinumab 150 or 75 mg every 4 weeks (q4Wk), following intravenous loading to Week (Wk) 4, or placebo treatment to Wk16/24. Up-titration from secukinumab 75-150 mg q4Wk was permitted following a protocol amendment. Efficacy is reported for patients originally randomized to secukinumab. Radiographic changes were assessed using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) and changes in MRI measures of inflammation using the Berlin scoring method. Safety and tolerability were evaluated.
Results
Among 274 extension study participants, 89.7% (78/87) and 93.0% (93/100) originally randomized to secukinumab 150 and 75 mg, respectively, completed 208Wk. Through Wk208, Assessment of Spondyloarthritis International Society 20/40 (observed) were 79.7%/60.8% (150 mg), 71.0%/43.5% (75 mg) and 80.0%/76% (up-titrators; n = 25). Mean (s.d.) changes in mSASSS were 1.2 (3.91) (150 mg), 1.8 (4.32) (75 mg) and 1.6 (5.67) (up-titrators). No radiographic progression (mSASSS change from Baseline < 2) was observed in 79% of patients receiving either secukinumab dose. Exposure-adjusted incidence rates per 100 patient-years were: serious infections (1.0), Candida infections (0.4), Crohn's disease (0.6), ulcerative colitis (0.2), and malignant/unspecified tumours (0.5), with no new safety signals.
Conclusion
Through 4 years, secukinumab provided sustained efficacy on signs and symptoms, and MRI outcomes, a low rate of radiographic progression and a consistent safety profile.
Trial registration
NCT01863732.
The lysosomal pathway of autophagy is the major catabolic mechanism for degrading long-lived cellular proteins and cytoplasmic organelles. Recent studies have also shown that autophagy (xenophagy) ...may be used to degrade bacterial pathogens that invade intracellularly. However, it is not yet known whether xenophagy is a mechanism for degrading viruses. Previously, we showed that autophagy induction requires the antiviral eIF2alpha kinase signaling pathway (including PKR and eIF2alpha) and that this function of eIF2alpha kinase signaling is antagonized by the herpes simplex virus (HSV-1) neurovirulence gene product, ICP34.5. Here, we show quantitative morphologic evidence of PKR-dependent xenophagic degradation of herpes simplex virions and biochemical evidence of PKR and eIF2alpha-dependent degradation of HSV-1 proteins, both of which are blocked by ICP34.5. Together, these findings indicate that xenophagy degrades HSV-1 and that this cellular function is antagonized by the HSV-1 neurovirulence gene product, ICP34.5. Thus, autophagy-related pathways are involved in degrading not only cellular constituents and intracellular bacteria, but also viruses.
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