AMPA Receptor Phosphorylation and Synaptic Colocalization on Motor Neurons Drive Maladaptive Plasticity below Complete Spinal Cord Injury.

Clinical spinal cord injury (SCI) is accompanied by comorbid peripheral injury in 47% of patients. Human and animal modeling data have shown that painful peripheral injuries undermine long-term recovery of locomotion through unknown mechanisms. Peripheral nociceptive stimuli induce maladaptive synaptic plasticity in dorsal horn sensory systems through AMPA receptor (AMPAR) phosphorylation and trafficking to synapses. Here we test whether ventral horn motor neurons in rats demonstrate similar experience-dependent maladaptive plasticity below a complete SCI in vivo. Quantitative biochemistry demonstrated that intermittent nociceptive stimulation (INS) rapidly and selectively increases AMPAR subunit GluA1 serine 831 phosphorylation and localization to synapses in the injured spinal cord, while reducing synaptic GluA2. These changes predict motor dysfunction in the absence of cell death signaling, suggesting an opportunity for therapeutic reversal. Automated confocal time-course analysis of lumbar ventral horn motor neurons confirmed a time-dependent increase in synaptic GluA1 with concurrent decrease in synaptic GluA2. Optical fractionation of neuronal plasma membranes revealed GluA2 removal from extrasynaptic sites on motor neurons early after INS followed by removal from synapses 2 h later. As GluA2-lacking AMPARs are canonical calcium-permeable AMPARs (CP-AMPARs), their stimulus- and time-dependent insertion provides a therapeutic target for limiting calcium-dependent dynamic maladaptive plasticity after SCI. Confirming this, a selective CP-AMPAR antagonist protected against INS-induced maladaptive spinal plasticity, restoring adaptive motor responses on a sensorimotor spinal training task. These findings highlight the critical involvement of AMPARs in experience-dependent spinal cord plasticity after injury and provide a pharmacologically targetable synaptic mechanism by which early postinjury experience shapes motor plasticity

The demographics of pain after spinal cord injury: a survey of our model system.

STUDY DESIGN: Survey OBJECTIVES: Better understand the demographics of pain after spinal cord injury (SCI). SETTING: Academic Level 1 trauma center and SCI Model System. METHODS: A survey including general demographic questions, questions of specific interest to the authors, the standardized SCI Pain Instrument (SCIPI), International SCI Pain Data Set, Basic form (ISCIPDS:B), Patient Reported Outcomes Measurement Information System (PROMIS) neuropathic 5a (PROMIS-Neur), and PROMIS nociceptive 5a (PROMIS-No). RESULTS: 81% of individuals with SCI experience chronic pain and 86% of individuals with pain have neuropathic pain. 55% of individuals had shoulder pain. Females and those who recall \u3e5/10 pain during initial hospital stay had significantly higher PROMIS-Neur scores. Completeness of injury correlates inversely with the degree of neuropathic pain. Those who recall \u3e5 pain during the initial hospital stay and those who reported the worst or second worst pain as being shoulder pain had significantly higher PROMIS-No scores. Lumbosacral injuries trended towards higher PROMIS-No scores and had the highest PROMIS-Neur scores. Those with tetraplegia were more likely to develop shoulder pain and those with shoulder pain had higher PROMIS-No scores. CONCLUSIONS: Chronic pain is almost universal in patients with SCI. Pain is more commonly reported as neuropathic in nature and females reported more neuropathic pain than males. Physicians should monitor for nociceptive shoulder pain, particularly in those with tetraplegia. Patients with incomplete injuries or lumbosacral injuries are more likely to report higher levels of neuropathic pain and pain levels should be monitored closely. Those with more neuropathic and nociceptive pain recall worse pain at initial hospitalization. Better understanding pain demographics in this population help screen, prevent and manage chronic pain in these patients

Human cytomegalovirus mediates APOBEC3B relocalization early during infection through a ribonucleotide reductase-independent mechanism

Human cytomegalovirus (HCMV) infections can range from asymptomatic to severe, particularly in neonates and immunocompromised patients. HCMV has evolved strategies to overcome host-encoded antiviral defenses to achieve lytic viral DNA replication and dissemination and, under some conditions, latency and long-term persistence. Here, we show that HCMV infection causes the antiviral factor, APOBEC3B, to relocalize from the nuclear compartment to the cytoplasm. This overall strategy resembles that used by related herpesviruses. However, the HCMV relocalization mechanism utilizes a different viral factor(s) and available evidence suggests the involvement of at least one protein expressed at the early stages of infection. This knowledge is important because a greater understanding of this mechanism could lead to novel antiviral strategies that enable APOBEC3B to naturally restrict HCMV infection.The APOBEC3 family of DNA cytosine deaminases comprises an important arm of the innate antiviral defense system. The gamma-herpesviruses Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus and the alpha-herpesviruses herpes simplex virus (HSV)-1 and HSV-2 have evolved an efficient mechanism to avoid APOBEC3 restriction by directly binding to APOBEC3B and facilitating its exclusion from the nuclear compartment. The only viral protein required for APOBEC3B relocalization is the large subunit of the ribonucleotide reductase (RNR). Here, we ask whether this APOBEC3B relocalization mechanism is conserved with the beta-herpesvirus human cytomegalovirus (HCMV). Although HCMV infection causes APOBEC3B relocalization from the nucleus to the cytoplasm in multiple cell types, the viral RNR (UL45) is not required. APOBEC3B relocalization occurs rapidly following infection suggesting the involvement of an immediate early or early (IE/E) viral protein. In support of this possibility, genetic (IE1 mutant) and pharmacologic (cycloheximide) strategies that prevent the expression of IE/E viral proteins also block APOBEC3B relocalization. In comparison, the treatment of infected cells with phosphonoacetic acid, which interferes with viral late protein expression, still permits A3B relocalization. These results combine to indicate that the beta-herpesvirus HCMV uses an RNR-independent, yet phenotypically similar, molecular mechanism to antagonize APOBEC3B. IMPORTANCEHuman cytomegalovirus (HCMV) infections can range from asymptomatic to severe, particularly in neonates and immunocompromised patients. HCMV has evolved strategies to overcome host-encoded antiviral defenses to achieve lytic viral DNA replication and dissemination and, under some conditions, latency and long-term persistence. Here, we show that HCMV infection causes the antiviral factor, APOBEC3B, to relocalize from the nuclear compartment to the cytoplasm. This overall strategy resembles that used by related herpesviruses. However, the HCMV relocalization mechanism utilizes a different viral factor(s) and available evidence suggests the involvement of at least one protein expressed at the early stages of infection. This knowledge is important because a greater understanding of this mechanism could lead to novel antiviral strategies that enable APOBEC3B to naturally restrict HCMV infection

Diagnostic accuracy and clinical impact of MRI-based technologies for patients with non-alcoholic fatty liver disease : systematic review and economic evaluation

BACKGROUND: Magnetic resonance imaging-based technologies are non-invasive diagnostic tests that can be used to assess non-alcoholic fatty liver disease. OBJECTIVES: The study objectives were to assess the diagnostic test accuracy, clinical impact and cost-effectiveness of two magnetic resonance imaging-based technologies (LiverMultiScan and magnetic resonance elastography) for patients with non-alcoholic fatty liver disease for whom advanced fibrosis or cirrhosis had not been diagnosed and who had indeterminate results from fibrosis testing, or for whom transient elastography or acoustic radiation force impulse was unsuitable, or who had discordant results from fibrosis testing. DATA SOURCES: The data sources searched were MEDLINE, MEDLINE Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Database of Controlled Trials, Database of Abstracts of Reviews of Effects and the Health Technology Assessment. METHODS: A systematic review was conducted using established methods. Diagnostic test accuracy estimates were calculated using bivariate models and a summary receiver operating characteristic curve was calculated using a hierarchical model. A simple decision-tree model was developed to generate cost-effectiveness results. RESULTS: The diagnostic test accuracy review (13 studies) and the clinical impact review (11 studies) only included one study that provided evidence for patients who had indeterminate or discordant results from fibrosis testing. No studies of patients for whom transient elastography or acoustic radiation force impulse were unsuitable were identified. Depending on fibrosis level, relevant published LiverMultiScan diagnostic test accuracy results ranged from 50% to 88% (sensitivity) and from 42% to 75% (specificity). No magnetic resonance elastography diagnostic test accuracy data were available for the specific population of interest. Results from the clinical impact review suggested that acceptability of LiverMultiScan was generally positive. To explore how the decision to proceed to biopsy is influenced by magnetic resonance imaging-based technologies, the External Assessment Group presented cost-effectiveness analyses for LiverMultiScan plus biopsy versus biopsy only. Base-case incremental cost-effectiveness ratio per quality-adjusted life year gained results for seven of the eight diagnostic test strategies considered showed that LiverMultiScan plus biopsy was dominated by biopsy only; for the remaining strategy (Brunt grade ≥2), the incremental cost-effectiveness ratio per quality-adjusted life year gained was £1,266,511. Results from threshold and scenario analyses demonstrated that External Assessment Group base-case results were robust to plausible variations in the magnitude of key parameters. LIMITATIONS: Diagnostic test accuracy, clinical impact and cost-effectiveness data for magnetic resonance imaging-based technologies for the population that is the focus of this assessment were limited. CONCLUSIONS: Magnetic resonance imaging-based technologies may be useful to identify patients who may benefit from additional testing in the form of liver biopsy and those for whom this additional testing may not be necessary. However, there is a paucity of diagnostic test accuracy and clinical impact data for patients who have indeterminate results from fibrosis testing, for whom transient elastography or acoustic radiation force impulse are unsuitable or who had discordant results from fibrosis testing. Given the External Assessment Group cost-effectiveness analyses assumptions, the use of LiverMultiScan and magnetic resonance elastography for assessing non-alcoholic fatty liver disease for patients with inconclusive results from previous fibrosis testing is unlikely to be a cost-effective use of National Health Service resources compared with liver biopsy only. STUDY REGISTRATION: This study is registered as PROSPERO CRD42021286891. FUNDING: Funding for this study was provided by the Evidence Synthesis Programme of the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 27, No. 10. See the NIHR Journals Library website for further project information