Blocking mitochondrial Zn2+ accumulation after ischemia reduces mitochondrial dysfunction and neuronal injury.

Zn2+ is an important contributor to ischemic brain injury and recent studies support the hypothesis that mitochondria are key sites of its injurious effects. In murine hippocampal slices (both sexes) subjected to oxygen glucose deprivation (OGD), we found that Zn2+ accumulation and its entry into mitochondria precedes and contributes to the induction of acute neuronal death. In addition, if the ischemic episode is short (and sublethal), there is ongoing Zn2+ accumulation in CA1 mitochondria after OGD that may contribute to their delayed dysfunction. Using this slice model of sublethal OGD, we have now examined Zn2+ contributions to the progression of changes evoked by OGD and occurring over 4-5 hours. We detected progressive mitochondrial depolarization occurring from ∼ 2 hours after ischemia, a large increase in spontaneous synaptic activity between 2-3 hours, and mitochondrial swelling and fragmentation at 4 hours. Blockade of the primary route for Zn2+ entry, the mitochondrial Ca2+ uniporter (MCU; with ruthenium red, RR) or Zn2+ chelation shortly after OGD withdrawal substantially attenuated the mitochondrial depolarization and the changes in synaptic activity. RR also largely reversed the mitochondrial swelling. Finally, using an in vivo rat (male) asphyxial cardiac arrest (CA) model of transient global ischemia, we found that ∼8 min asphyxia induces considerable injury of CA1 neurons 4 hours later that is associated with strong Zn2+ accumulation within many damaged mitochondria. These effects were substantially attenuated by infusion of RR upon reperfusion. Our findings highlight mitochondrial Zn2+ accumulation after ischemia as a possible target for neuroprotective therapy.SIGNIFICANCE STATEMENT:Brain ischemia is a leading cause of mortality and long-term disability that still lacks effective treatment. After transient ischemia delayed death of neurons occurs in vulnerable brain regions. There is a critical need to understand mechanisms of this delayed neurodegeneration which can be targeted for neuroprotection. We found progressive and long-lasting mitochondrial Zn2+ accumulation to occur in highly vulnerable CA1 neurons after ischemia. Here we demonstrate that this Zn2+ accumulation contributes strongly to deleterious events occurring after ischemia including mitochondrial dysfunction, swelling and structural changes. We suggest that this mitochondrial Zn2+ entry may constitute a promising target for development of therapeutic interventions to be delivered after termination of an episode of transient global ischemia.

VCP/p97 inhibitor CB-5083 modulates muscle pathology in a mouse model of VCP inclusion body myopathy.

BACKGROUND: Pathogenic gain of function variants in Valosin-containing protein (VCP) cause a unique disease characterized by inclusion body myopathy with early-onset Paget disease of bone and frontotemporal dementia (also known as Multisystem proteinopathy (MSP)). Previous studies in drosophila models of VCP disease indicate treatment with VCP inhibitors mitigates disease pathology. Earlier-generation VCP inhibitors display off-target effects and relatively low therapeutic potency. New generation of VCP inhibitors needs to be evaluated in a mouse model of VCP disease. In this study, we tested the safety and efficacy of a novel and potent VCP inhibitor, CB-5083 using VCP patient-derived myoblast cells and an animal model of VCP disease. METHODS: First, we analyzed the effect of CB-5083 in patient-derived myoblasts on the typical disease autophagy and TDP-43 profile by Western blot. Next, we determined the maximum tolerated dosage of CB-5083 in mice and treated the 2-month-old VCPR155H/R155H mice for 5 months with 15 mg/kg CB-5083. We analyzed motor function monthly by Rotarod; and we assessed the end-point blood toxicology, and the muscle and brain pathology, including autophagy and TDP-43 profile, using Western blot and immunohistochemistry. We also treated 12-month-old VCPR155H/+ mice for 6 months and performed similar analysis. Finally, we assessed the potential side effects of CB-5083 on retinal function, using electroretinography in chronically treated VCPR155H/155H mice. RESULTS: In vitro analyses using patient-derived myoblasts confirmed that CB-5083 can modulate expression of the proteins in the autophagy pathways. We found that chronic CB-5083 treatment is well tolerated in the homozygous mice harboring patient-specific VCP variant, R155H, and can ameliorate the muscle pathology characteristic of the disease. VCP-associated pathology biomarkers, such as elevated TDP-43 and p62 levels, were significantly reduced. Finally, to address the potential adverse effect of CB-5083 on visual function observed in a previous oncology clinical trial, we analyzed retinal function in mice treated with moderate doses of CB-5083 for 5 months and documented the absence of permanent ocular toxicity. CONCLUSIONS: Altogether, these findings suggest that long-term use of CB-5083 by moderate doses is safe and can improve VCP disease-associated muscle pathology. Our results provide translationally relevant evidence that VCP inhibitors could be beneficial in the treatment of VCP disease.

Powassan Virus Infection Likely Acquired Through Blood Transfusion Presenting as Encephalitis in a Kidney Transplant Recipient.

A kidney transplant patient without known tick exposure developed encephalitis 3 weeks after transplantation. During the transplant hospitalization, the patient had received a blood transfusion from an asymptomatic donor later discovered to have been infected with Powassan virus. Here, we describe a probable instance of transfusion-transmitted Powassan virus infection.

Impact of the hematocrit value of the blood prime unit on patient hematocrit values after therapeutic plasma exchange in children weighing 10 kg or less.

We report the impact of measuring the hematocrit (HCT) of blood prime units (BPUs) on postprocedure patient HCT values in a small child with transverse myelitis undergoing therapeutic plasma exchange (TPE). Initially, the BPU HCT values were not measured, according to our apheresis policy of using our blood center's estimated HCT value. This approach resulted in unexpected increasing elevations of our patient's post-TPE HCT after the first two TPE procedures. Subsequent measurement of the BPU HCT prior to use stabilized the patient's post-TPE HCT. To our knowledge, this is the first case report describing the impact of using the measured BPU HCT vs the estimated HCT for very small children undergoing therapeutic apheresis. Our standard operating procedure for very small children has been updated after this patient's case to include measurements of the HCT values of BPUs for children who weigh 10 kg or less.

Differential Vulnerability of CA1 versus CA3 Pyramidal Neurons After Ischemia: Possible Relationship to Sources of Zn2+ Accumulation and Its Entry into and Prolonged Effects on Mitochondria.

Excitotoxic mechanisms contribute to the degeneration of hippocampal pyramidal neurons after recurrent seizures and brain ischemia. However, susceptibility differs, with CA1 neurons degenerating preferentially after global ischemia and CA3 neurons after limbic seizures. Whereas most studies address contributions of excitotoxic Ca2+ entry, it is apparent that Zn2+ also contributes, reflecting accumulation in neurons either after synaptic release and entry through postsynaptic channels or upon mobilization from intracellular Zn2+-binding proteins such as metallothionein-III (MT-III). Using mouse hippocampal slices to study acute oxygen glucose deprivation (OGD)-triggered neurodegeneration, we found evidence for early contributions of excitotoxic Ca2+ and Zn2+ accumulation in both CA1 and CA3, as indicated by the ability of Zn2+ chelators or Ca2+ entry blockers to delay pyramidal neuronal death in both regions. However, using knock-out animals (of MT-III and vesicular Zn2+ transporter, ZnT3) and channel blockers revealed substantial differences in relevant Zn2+ sources, with critical contributions of presynaptic release and its permeation through Ca2+- (and Zn2+)-permeable AMPA channels in CA3 and Zn2+ mobilization from MT-III predominating in CA1. To assess the consequences of the intracellular Zn2+ accumulation, we used OGD exposures slightly shorter than those causing acute neuronal death; under these conditions, cytosolic Zn2+ rises persisted for 10-30 min after OGD, followed by recovery over ∼40-60 min. Furthermore, the recovery appeared to be accompanied by mitochondrial Zn2+ accumulation (via the mitochondrial Ca2+ uniporter MCU) in CA1 but not in CA3 neurons and was markedly diminished in MT-III knock-outs, suggesting that it depended upon Zn2+ mobilization from this protein. SIGNIFICANCE STATEMENT: The basis for the differential vulnerabilities of CA1 versus CA3 pyramidal neurons is unclear. The present study of events during and after acute oxygen glucose deprivation highlights a possible important difference, with rapid synaptic entry of Ca2+ and Zn2+ contributing more in CA3, but with delayed and long-lasting accumulation of Zn2+ within mitochondria occurring in CA1 but not CA3 pyramidal neurons. These data may be consistent with observations of prominent mitochondrial dysfunction as a critical early event in the delayed degeneration of CA1 neurons after ischemia and support a hypothesis that mitochondrial Zn2+ accumulation in the early reperfusion period may be a critical and targetable upstream event in the injury cascade.

Red blood cell exchange in patients with sickle cell disease-indications and management: a review and consensus report by the therapeutic apheresis subsection of the AABB.

BACKGROUND: A prior practice survey revealed variations in the management of patients with sickle cell disease (SCD) and stressed the need for comprehensive guidelines. Here we discuss: 1) common indications for red blood cell exchange (RCE), 2) options for access, 3) how to prepare the red blood cells (RBCs) to be used for RCE, 4) target hemoglobin (Hb) and/or hematocrit (Hct) and HbS level, 5) RBC depletion/RCE, and 6) some complications that may ensue. STUDY DESIGN AND METHODS: Fifteen physicians actively practicing apheresis from 14 institutions representing different areas within the United States discussed how they manage RCE for patients with SCD. RESULTS: Simple transfusion is recommended to treat symptomatic anemia with Hb level of less than 9 g/dL. RCE is indicated to prevent or treat complications arising from the presence of HbS. The most important goals are reduction of HbS while also preventing hyperviscosity. The usual goals are a target HbS level of not more than 30% and Hct level of less than 30%. CONCLUSION: Although a consensus as to protocol details may not be possible, there are areas of agreement in the management of these patients, for example, that it is optimal to avoid hyperviscosity and iron overload, that a target Hb S level in the range of 30% is generally desirable, and that RCE as an acute treatment for pain crisis in the absence of other acute or chronic conditions is ordinarily discouraged.

The management of anticoagulation in patients undergoing therapeutic plasma exchange: A concise review.

We surveyed multiple apheresis centers represented by the authors for their clinical approach to the management of anticoagulation issues during therapeutic plasma exchange (TPE). We present the results of their practices and a review of the pertinent literature. As plasma is removed during TPE, replacement with all or partial non-plasma-containing fluids (eg, 5% albumin) may lead to significant changes in hemostasis. These changes are amplified in patients who are receiving anticoagulation. We discuss various anticoagulants as well as the monitoring and adjustment of anticoagulation before, during, and after TPE. No single guideline can be applied, but rather, patients must be monitored individually, taking into account their often complex clinical conditions and medication profiles.

A Novel Methodology for Improving Plant Pest Surveillance in Vineyards and Crops Using UAV-Based Hyperspectral and Spatial Data.

Recent advances in remote sensed imagery and geospatial image processing using unmanned aerial vehicles (UAVs) have enabled the rapid and ongoing development of monitoring tools for crop management and the detection/surveillance of insect pests. This paper describes a (UAV) remote sensing-based methodology to increase the efficiency of existing surveillance practices (human inspectors and insect traps) for detecting pest infestations (e.g., grape phylloxera in vineyards). The methodology uses a UAV integrated with advanced digital hyperspectral, multispectral, and RGB sensors. We implemented the methodology for the development of a predictive model for phylloxera detection. In this method, we explore the combination of airborne RGB, multispectral, and hyperspectral imagery with ground-based data at two separate time periods and under different levels of phylloxera infestation. We describe the technology used-the sensors, the UAV, and the flight operations-the processing workflow of the datasets from each imagery type, and the methods for combining multiple airborne with ground-based datasets. Finally, we present relevant results of correlation between the different processed datasets. The objective of this research is to develop a novel methodology for collecting, processing, analising and integrating multispectral, hyperspectral, ground and spatial data to remote sense different variables in different applications, such as, in this case, plant pest surveillance. The development of such methodology would provide researchers, agronomists, and UAV practitioners reliable data collection protocols and methods to achieve faster processing techniques and integrate multiple sources of data in diverse remote sensing applications.

Transmission of Babesia microti Parasites by Solid Organ Transplantation.

Babesia microti, an intraerythrocytic parasite, is tickborne in nature. In contrast to transmission by blood transfusion, which has been well documented, transmission associated with solid organ transplantation has not been reported. We describe parasitologically confirmed cases of babesiosis diagnosed ≈8 weeks posttransplantation in 2 recipients of renal allografts from an organ donor who was multiply transfused on the day he died from traumatic injuries. The organ donor and recipients had no identified risk factors for tickborne infection. Antibodies against B. microti parasites were not detected by serologic testing of archived pretransplant specimens. However, 1 of the organ donor's blood donors was seropositive when tested postdonation and had risk factors for tick exposure. The organ donor probably served as a conduit of Babesia parasites from the seropositive blood donor to both kidney recipients. Babesiosis should be included in the differential diagnosis of unexplained fever and hemolytic anemia after blood transfusion or organ transplantation.

Intramitochondrial Zn2+ accumulation via the Ca2+ uniporter contributes to acute ischemic neurodegeneration.

Ca(2+) and Zn(2+) have both been implicated in the induction of acute ischemic neurodegeneration. We recently examined changes in intracellular Zn(2+) and Ca(2+) in CA1 pyramidal neurons subjected to oxygen glucose deprivation (OGD), and found that Zn(2+) rises precede and contribute to the onset of terminal Ca(2+) rises ("Ca(2+) deregulation"), which are causatively linked to a lethal loss of membrane integrity. The present study seeks to examine the specific role of intramitochondrial Zn(2+) accumulation in ischemic injury, using blockers of the mitochondrial Ca(2+) uniporter (MCU), through which both Zn(2+) and Ca(2+) appear able to enter the mitochondrial matrix. In physiological extracellular Ca(2+), treatment with the MCU blocker, Ruthenium Red (RR), accelerated the Ca(2+) deregulation, most likely by disrupting mitochondrial Ca(2+) buffering and thus accelerating the lethal cytosolic Ca(2+) overload. However, when intracellular Ca(2+) overload was slowed, either by adding blockers of major Ca(2+) entry channels or by lowering the concentration of Ca(2+) in the extracellular buffer, Ca(2+) deregulation was delayed, and under these conditions either Zn(2+) chelation or MCU blockade resulted in similar further delays of the Ca(2+) deregulation. In parallel studies using the reactive oxygen species (ROS) indicator, hydroethidine, lowering Ca(2+) surprisingly accelerated OGD induced ROS generation, and in these low Ca(2+) conditions, either Zn(2+) chelation or MCU block slowed the ROS generation. These studies suggest that, during acute ischemia, Zn(2+) entry into mitochondria via the MCU induces mitochondrial dysfunction (including ROS generation) that occurs upstream of, and contributes to the terminal Ca(2+) deregulation.

Skeletal muscle effects of antisense oligonucleotides targeting glycogen synthase 1 in a mouse model of Pompe disease.

Pompe disease (PD) is a progressive myopathy caused by the aberrant accumulation of glycogen in skeletal and cardiac muscle resulting from the deficiency of the enzyme acid alpha-glucosidase (GAA). Administration of recombinant human GAA as enzyme replacement therapy (ERT) works well in alleviating the cardiac manifestations of PD but loses sustained benefit in ameliorating the skeletal muscle pathology. The limited efficacy of ERT in skeletal muscle is partially attributable to its inability to curb the accumulation of new glycogen produced by the muscle enzyme glycogen synthase 1 (GYS1). Substrate reduction therapies aimed at knocking down GYS1 expression represent a promising avenue to improve Pompe myopathy. However, finding specific inhibitors for GYS1 is challenging given the presence of the highly homologous GYS2 in the liver. Antisense oligonucleotides (ASOs) are chemically modified oligomers that hybridize to their complementary target RNA to induce their degradation with exquisite specificity. In the present study, we show that ASO-mediated Gys1 knockdown in the Gaa -/- mouse model of PD led to a robust reduction in glycogen accumulation in skeletal and cardiac muscle. In addition, combining Gys1 ASO with ERT further reduced glycogen content in muscle, eliminated autophagic buildup and lysosomal dysfunction, and improved motor function in Gaa -/- mice. Our results provide a strong foundation for further validation of the use of Gys1 ASO, alone or in combination with ERT, as a therapy for PD. We propose that early administration of Gys1 ASO in combination with ERT may be the key to preventative treatment options in PD.

A progressive translational mouse model of human valosin-containing protein disease: the VCP(R155H/+) mouse.

INTRODUCTION: Mutations in the valosin-containing protein (VCP) gene cause hereditary inclusion body myopathy (IBM) associated with Paget disease of bone (PDB), and frontotemporal dementia (FTD). More recently, these mutations have been linked to 2% of familial amyotrophic lateral sclerosis (ALS) cases. A knock-in mouse model offers the opportunity to study VCP-associated pathogenesis. METHODS: The VCP(R155H/+) knock-in mouse model was assessed for muscle strength and immunohistochemical, Western blot, apoptosis, autophagy, and microPET/CT imaging analyses. RESULTS: VCP(R155H/+) mice developed significant progressive muscle weakness, and the quadriceps and brain developed progressive cytoplasmic accumulation of TDP-43, ubiquitin-positive inclusion bodies, and increased LC3-II staining. MicroCT analyses revealed Paget-like lesions at the ends of long bones. Spinal cord demonstrated neurodegenerative changes, ubiquitin, and TDP-43 pathology of motor neurons. CONCLUSIONS: VCP(R155H/+) knock-in mice represent an excellent preclinical model for understanding VCP-associated disease mechanisms and future treatments.

MacroH2A histone variants modulate enhancer activity to repress oncogenic programs and cellular reprogramming.

Considerable efforts have been made to characterize active enhancer elements, which can be annotated by accessible chromatin and H3 lysine 27 acetylation (H3K27ac). However, apart from poised enhancers that are observed in early stages of development and putative silencers, the functional significance of cis-regulatory elements lacking H3K27ac is poorly understood. Here we show that macroH2A histone variants mark a subset of enhancers in normal and cancer cells, which we coined 'macro-Bound Enhancers', that modulate enhancer activity. We find macroH2A variants localized at enhancer elements that are devoid of H3K27ac in a cell type-specific manner, indicating a role for macroH2A at inactive enhancers to maintain cell identity. In following, reactivation of macro-bound enhancers is associated with oncogenic programs in breast cancer and their repressive role is correlated with the activity of macroH2A2 as a negative regulator of BRD4 chromatin occupancy. Finally, through single cell epigenomic profiling of normal mammary stem cells derived from mice, we show that macroH2A deficiency facilitates increased activity of transcription factors associated with stem cell activity.

Cancer stem cells from a rare form of glioblastoma multiforme involving the neurogenic ventricular wall.

BACKGROUND: The cancer stem cell (CSC) hypothesis posits that deregulated neural stem cells (NSCs) form the basis of brain tumors such as glioblastoma multiforme (GBM). GBM, however, usually forms in the cerebral white matter while normal NSCs reside in subventricular and hippocampal regions. We attempted to characterize CSCs from a rare form of glioblastoma multiforme involving the neurogenic ventricular wall. METHODS: We described isolating CSCs from a GBM involving the lateral ventricles and characterized these cells with in vitro molecular biomarker profiling, cellular behavior, ex vivo and in vivo techniques. RESULTS: The patient's MRI revealed a heterogeneous mass with associated edema, involving the left subventricular zone. Histological examination of the tumor established it as being a high-grade glial neoplasm, characterized by polygonal and fusiform cells with marked nuclear atypia, amphophilic cytoplasm, prominent nucleoli, frequent mitotic figures, irregular zones of necrosis and vascular hyperplasia. Recurrence of the tumor occurred shortly after the surgical resection. CD133-positive cells, isolated from the tumor, expressed stem cell markers including nestin, CD133, Ki67, Sox2, EFNB1, EFNB2, EFNB3, Cav-1, Musashi, Nucleostemin, Notch 2, Notch 4, and Pax6. Biomarkers expressed in differentiated cells included Cathepsin L, Cathepsin B, Mucin18, Mucin24, c-Myc, NSE, and TIMP1. Expression of unique cancer-related transcripts in these CD133-positive cells, such as caveolin-1 and -2, do not appear to have been previously reported in the literature. Ex vivo organotypic brain slice co-culture showed that the CD133+ cells behaved like tumor cells. The CD133-positive cells also induced tumor formation when they were stereotactically transplanted into the brains of the immune-deficient NOD/SCID mice. CONCLUSIONS: This brain tumor involving the neurogenic lateral ventricular wall was comprised of tumor-forming, CD133-positive cancer stem cells, which are likely the driving force for the rapid recurrence of the tumor in the patient.

100-metre-diameter moonlets in Saturn's A ring from observations of 'propeller' structures.

Saturn's main rings are composed predominantly of water-ice particles ranging between about 1 centimetre and 10 metres in radius. Above this size range, the number of particles drops sharply, according to the interpretation of spacecraft and stellar occultations. Other than the gap moons Pan and Daphnis (the provisional name of S/2005 S1), which have sizes of several kilometres, no individual bodies in the rings have been directly observed, and the population of ring particles larger than ten metres has been essentially unknown. Here we report the observation of four longitudinal double-streaks in an otherwise bland part of the mid-A ring. We infer that these 'propeller'-shaped perturbations arise from the effects of embedded moonlets approximately 40 to 120 m in diameter. Direct observation of this phenomenon validates models of proto-planetary disks in which similar processes are posited. A population of moonlets, as implied by the size distribution that we find, could help explain gaps in the more tenuous regions of the Cassini division and the C ring. The existence of such large embedded moonlets is most naturally compatible with a ring originating in the break-up of a larger body, but accretion from a circumplanetary disk is also plausible if subsequent growth onto large particles occurs after the primary accretion phase has concluded.

Anti-SARS-CoV-2 IgG and IgA antibodies in COVID-19 convalescent plasma do not enhance viral infection.

The novel coronavirus, SARS-CoV-2 that causes COVID-19 has resulted in the death of nearly 4 million people within the last 18 months. While preventive vaccination, and monoclonal antibody therapies have been rapidly developed and deployed, early in the pandemic the use of COVID-19 convalescent plasma (CCP) was a common means of passive immunization with a theoretical risk of antibody-dependent enhancement (ADE) of viral infection. Though vaccines elicit a strong and protective immune response and transfusion of CCP with high titers of neutralization activity are correlated with better clinical outcomes, the question of whether antibodies in CCP can enhance infection of SARS-CoV-2 has not been directly addressed. In this study, we analyzed for and observed passive transfer of neutralization activity with CCP transfusion. Furthermore, to specifically understand if antibodies against the spike protein (S) enhance infection, we measured the anti-S IgG, IgA, and IgM responses and adapted retroviral-pseudotypes to measure virus neutralization with target cells expressing the ACE2 virus receptor and the Fc alpha receptor (FcαR) or Fc gamma receptor IIA (FcγRIIA). Whereas neutralizing activity of CCP correlated best with higher titers of anti-S IgG antibodies, the neutralizing titer was not affected when Fc receptors were present on target cells. These observations support the absence of antibody-dependent enhancement of infection (ADE) by IgG and IgA isotypes found in CCP. The results presented, therefore, not only supports the therapeutic use of currently available antibody-based treatment, including the continuation of CCP transfusion strategies, but also the use of various vaccine platforms in a prophylactic approach.

Efficacy of COVID-19 Convalescent Plasma Based on Antibody Concentration.

Background: Convalescent plasma obtained from individuals who have recovered from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contains neutralizing antibodies to the virus and has been frequently used as a treatment in hospitalized patients with severe COVID-19. Methods: We conducted a retrospective, observational cohort study involving 96 hospitalized patients with severe COVID-19 who were allocated in a 1 : 1 ratio to having received either high antibody concentration convalescent plasma or low antibody concentration convalescent plasma. Quantitative measurements of IgG to the receptor-binding domain (RBD), the S1 subunit of the spike protein, and the SARS-CoV-2 nucleocapsid (N) protein were determined from donor plasma samples. The primary outcome was all-cause mortality within 30 days following convalescent plasma administration in regard to each of the three antibody domains. Results: Within the nucleocapsid antibody domain, death occurred in 22.2% of patients in the low antibody concentration group versus 23.5% in the high antibody concentration group (p=0.88). Within the RBD antibody domain, death occurred in 22.9% of patients in both the low and the high antibody concentration groups (p=1.0). Within the S1 subunit antibody domain, death occurred in 27.1% of patients in the low antibody concentration group versus 18.8% in the high antibody concentration group (p=0.33). Conclusions: No significant differences were observed between low and high concentration convalescent plasma in regard to overall mortality at 30 days, hospital length of stay, number of ventilator days, and subsequent receipt of invasive mechanical ventilation in patients who were previously not receiving mechanical ventilation. Trial Registration. This study was not associated with a clinical trial due to the retrospective nature of study design.

The Multifaceted Roles of Zinc in Neuronal Mitochondrial Dysfunction.

Zinc is a highly abundant cation in the brain, essential for cellular functions, including transcription, enzymatic activity, and cell signaling. However, zinc can also trigger injurious cascades in neurons, contributing to the pathology of neurodegenerative diseases. Mitochondria, critical for meeting the high energy demands of the central nervous system (CNS), are a principal target of the deleterious actions of zinc. An increasing body of work suggests that intracellular zinc can, under certain circumstances, contribute to neuronal damage by inhibiting mitochondrial energy processes, including dissipation of the mitochondrial membrane potential (MMP), leading to ATP depletion. Additional consequences of zinc-mediated mitochondrial damage include reactive oxygen species (ROS) generation, mitochondrial permeability transition, and excitotoxic calcium deregulation. Zinc can also induce mitochondrial fission, resulting in mitochondrial fragmentation, as well as inhibition of mitochondrial motility. Here, we review the known mechanisms responsible for the deleterious actions of zinc on the organelle, within the context of neuronal injury associated with neurodegenerative processes. Elucidating the critical contributions of zinc-induced mitochondrial defects to neurotoxicity and neurodegeneration may provide insight into novel therapeutic targets in the clinical setting.

Anti-SARS-CoV-2 IgG and IgA antibodies in COVID-19 convalescent plasma do not facilitate antibody-dependent enhance of viral infection.

The novel coronavirus SARS-CoV2, which causes COVID-19, has resulted in the death of nearly 4 million people within the last 18 months. While preventive vaccination and monoclonal antibody therapies have been rapidly developed and deployed, early in the pandemic the use of COVID-19 convalescent plasma (CCP) was a common means of passive immunization, with the theoretical risk of antibody-dependent enhancement (ADE) of viral infection remaining undetermined. Though vaccines elicit a strong and protective immune response, and transfusion of CCP with high titers of neutralization activity are correlated with better clinical outcomes, the question of whether antibodies in CCP can enhance infection of SARS-CoV2 has not been directly addressed. In this study, we analyzed for and observed passive transfer of neutralization activity with CCP transfusion. Furthermore, to specifically understand if antibodies against the spike protein (S) enhance infection, we measured the anti-S IgG, IgA, and IgM responses and adapted retroviral-pseudotypes to measure virus neutralization with target cells expressing the ACE2 virus receptor and the Fc alpha receptor (FcαR) or Fc gamma receptor IIA (FcγRIIA). Whereas neutralizing activity of CCP correlated best with higher titers of anti-S IgG antibodies, the neutralizing titer was not affected when Fc receptors were present on target cells. These observations support the absence of antibody-dependent enhancement of infection (ADE) by IgG and IgA isotypes found in CCP. The results presented, therefore, support the clinical use of currently available antibody-based treatment including the continued study of CCP transfusion strategies.

Donor Anti-Spike Immunity is Related to Recipient Recovery and Can Predict the Efficacy of Convalescent Plasma Units.

BACKGROUND: The novel coronavirus, SARS-CoV2 that causes COVID-19 has resulted in the death of more than 2.31 million people within the last year and yet no cure exists. Whereas passive immunization with COVID-19 convalescent plasma (CCP) provides a safe and viable option, selection of optimal units for therapy and lack of clear therapeutic benefit from transfusion remain as barriers to the use of CCP. STUDY DESIGN AND METHODS: To identify plasma that is expected to benefit recipients, we measured anti-SARS-CoV2 antibody levels using clinically available serological assays and correlated with the neutralizing activity of CCP from donors. Neutralizing titer of plasma samples was measured by assaying infectivity of SARS-CoV-2 spike protein pseudotyped retrovirus particles in the presence of dilutions of plasma samples. We also used this assay to identify evidence of passive transfusion of neutralizing activity in CCP recipients. RESULTS: Viral neutralization and anti-spike protein antibodies in 109 samples from 87 plasma donors were highly varied but modestly correlated with each other. Recipients who died of COVID-19 were found to have been transfused with units with lower anti-spike antibody levels and neutralizing activity. Passive transfer of neutralization activity was documented in 62% of antibody naive plasma recipients. CONCLUSIONS: Since viral neutralization is the goal of CCP transfusion, our observations not only support the use of anti-spike SARS-CoV2 serology tests to identify beneficial CCP units, but also support the therapeutic value of convalescent plasma with high titers of anti-spike antibodies.