Michael S Pollanen’s research while affiliated with University of Toronto and other places

Objective This study was undertaken to understand the circumstances surrounding pediatric sudden unexpected death in epilepsy (SUDEP) and identify clinical factors that may be associated with SUDEP in childhood. Methods A retrospective case series was conducted. Pediatric SUDEP cases were collected across Canada from the Ontario Forensic Pathology Service, Canadian Pediatric Surveillance Program, and Canadian Pediatric Epilepsy Network. Demographics, epilepsy history, comorbidities, and circumstances surrounding death were analyzed. Results Forty‐nine children with pediatric SUDEP were analyzed; 25 (51%) were females, and the median age at death was 8 years. Six children (12%) were <2 years of age at the time of death. Information on seizure types 6 months before death was known in 35 children. Twenty‐two had tonic–clonic seizures within the last 6 months prior to death (63%). Seven children (18%) had no tonic–clonic seizures in their lifetime. Two thirds of children were treated with ≥2 antiseizure medications. Genetic etiologies were most common (55%). Data on global developmental delay (GDD) was known in 46 children; 12 children (26%) had no impairment, and 34 were globally delayed (74%). Children with GDD had earlier age at seizure onset (p < .001); however, epilepsy duration was similar to those without GDD (p = .170). Similar to adult cohorts, death was often unwitnessed (n = 41/46, 89%). Information on recent infection before death was known in 37 children. Seventeen children (46%) had a recent infection. Significance Our study represents the largest pediatric SUDEP case series to date. SUDEP occurred in children of all ages, including infants, with a spectrum of epilepsies with and without neurodevelopmental impairment. The circumstances around death (i.e., timing of death, witnessed/unwitnessed) were similar to previous SUDEP cohorts. A recent infection was often observed, which could decrease seizure threshold and trigger a terminal seizure and may suggest that times of increased seizure risk could warrant heightened surveillance for SUDEP. However, further research is needed to determine the significance of this finding.

A 52-year-old woman with of neck pain underwent percutaneous neck injection of local anesthetic and a corticosteroid without image guidance. She collapsed asystolic during the procedure was resuscitated and then died after 2 weeks in the intensive care unit with hypoxic encephalopathy. Complete postmortem examination included additional posterior neck dissection and cervical spinal cord removal with intact dura mater. The entire cervical spinal cord with the dura and leptomeninges was embedded in an oriented sequence of several paraffin blocks. Serial sections of each selected blocks were then studied to locate a putative puncture site. Serial sections from the third and fourth cervical levels (C3-C4) were stained with luxol fast blue-hematoxylin-eosin, iron stain, trichrome stain, and immunostained for b-amyloid precursor protein, and CD68. Histological examination revealed a linear needle track with a subacute healing reaction. The path included the dorsal spinal dura, arachnoid, and the left dorsal column. Clinicopathological correlation and the cause of death are discussed. Careful planning, dissection, sampling, and oriented serial sectioning with immunostaining were key points to document the injuries and understand this case.

Introduction Sudden Unexpected Death in Epilepsy (SUDEP) is the leading epilepsy-related cause of death, affecting approximately 1 per 1,000 individuals with epilepsy per year. Genetic variants that affect autonomic function, such as genes associated with cardiac arrhythmias, may predispose people with epilepsy to greater risk of both sudden cardiac death and SUDEP. Advances in next generation sequencing allow for the exploration of gene variants as potential biomarkers. Methods Genetic testing for the presence of cardiac arrhythmia and epilepsy gene variants was performed via genetic panels in 39 cases of SUDEP identified via autopsy by the Ontario Forensic Pathology Service. Variants were summarized by in-silico evidence for pathogenicity from 4 algorithms (SIFT, PolyPhen-2, PROVEAN, Mutation Taster) and allele frequencies in the general population (GnomAD). A maximum credible population allele frequency of 0.00004 was calculated based on epilepsy prevalence and SUDEP incidence to assess whether a variant was compatible with a pathogenic interpretation. Results Median age at the time of death was 33.3 years (range: 2, 60). Fifty-nine percent (n=23) were male. Gene panels detected 62 unique variants in 45 genes: 19 on the arrhythmia panel and 26 on the epilepsy panel. At least one variant was identified in 28 (72%) of decedents. Missense mutations comprised 57 (92%) of the observed variants. At least three in silico models predicted 12 (46%) cardiac arrhythmia panel missense variants and 20 (65%) epilepsy panel missense variants were pathogenic. Population allele frequencies were <0.00004 for 11 (42%) of the cardiac variants and 10 (32%) of the epilepsy variants. Together, these metrics identified 13 SUDEP variants of interest. Discussion Nearly three-quarters of decedents in this SUDEP cohort carried variants in comprehensive epilepsy or cardiac arrhythmia gene panels, with more than a third having variants in both panels. The proportion of decedents with cardiac variants aligns with recent studies of the disproportionate cardiac burden the epilepsy community faces compared to the general population and suggests a possible cardiac contribution to epilepsy mortality. These results identified 13 priority targets for future functional studies of these genes potential role in sudden death and demonstrates the necessity for further exploration of potential genetic contributions to SUDEP.

Nodding syndrome is a neurological disease of children in northern Uganda. Infection with the nematode parasite Onchocerca volvulus has been epidemiologically implicated as the cause of the disease. It has been proposed that an autoantibody directed against the human protein leiomodin-1 cross reacts with a tropomyosin-like nematode protein, thus suggesting that nodding syndrome is an autoimmune brain disease due to extra-cerebral parasitism. This hypothesis is dependent on constitutive neuronal expression of leiomodin-1. We tested this hypothesis by studying the distribution of leiomodin-1 in the normal human brain and other human tissues using immunohistochemistry. We found that immunostaining for leiomodin-1 follows a smooth muscle cell specific pattern. In the brain, it is confined to the smooth muscle cells of cerebral blood vessels and is not generally present in neurons or glia. However, immunoreactivity was identified in human Purkinje cell membrane and the body wall of C. elegans (as a proxy for Onchocerca volvulus) but only when immunostained with an antibody recognizing the N-terminal of leiomodin-1. Homology between leiomodin-1 and tropomodulin, specifically at the N-terminus, could explain why leiomodin-1 antibody cross reactivity between human Purkinje cells and C. elegans. However, we cannot provide proof confirming that the immunoreactivity in the membranes of Purkinje cells is specifically caused by the expression of tropomodulin. To overcome this limitation, further investigations using additional immunohistochemical and biochemical studies are required to corroborate our findings and provide more comprehensive evidence. Nevertheless, our findings do not support to the autoim-munity hypothesis involving Onchocerca volvulus and leiomodin-1. To gain a more comprehensive understanding of the cause and pathogenesis of NS, it is essential to explore alternative hypotheses.

SARS-CoV-2-mediated interactions with drug metabolizing enzymes and membrane transporters (DMETs) in different tissues, especially lung, the main affected organ may limit the clinical efficacy and safety profile of promising COVID-19 drugs. Herein, we investigated whether SARS-CoV-2 infection could dysregulate the expression of 25 clinically relevant DMETs in Vero E6 cells and postmortem lung tissues from COVID-19 patients. Also, we assessed the role of 2 inflammatory and 4 regulatory proteins in modulating the dysregulation of DMETs in human lung tissues. We showed for the first time that SARS-CoV-2 infection dysregulates CYP3A4 and UGT1A1 at the mRNA level, as well as P-gp and MRP1 at the protein level, in Vero E6 cells and postmortem human lung tissues, respectively. We observed that at the cellular level, DMETs could potentially be dysregulated by SARS-CoV-2-associated inflammatory response and lung injury. We uncovered the pulmonary cellular localization of CYP1A2, CYP2C8, CYP2C9, and CYP2D6, as well as ENT1 and ENT2 in human lung tissues, and observed that the presence of inflammatory cells is the major driving force for the discrepancy in the localization of DMETs between COVID-19 and control human lung tissues. Because alveolar epithelial cells and lymphocytes are both sites of SARS-CoV-2 infection and localization of DMETs, we recommend further investigation of the pulmonary pharmacokinetic profile of current COVID-19 drug dosing regimen to improve clinical outcomes.

Nodding syndrome is an enigmatic recurrent epidemic neurologic disease that affects children in East Africa. The illness begins with vertical nodding of the head and can progress to grand mal seizures and death after several years. The most recent outbreak of nodding syndrome occurred in northern Uganda. We now describe the clinicopathologic spectrum of nodding syndrome in northern Uganda. The neuropathologic findings of 16 children or young adults with fatal nodding syndrome were correlated with the onset, duration, and progression of their neurological illness. The affected individuals ranged in age from 14 to 25 years at the time of death, with a duration of illness ranging from 6-15 years. All 16 cases had chronic seizures. In ten cases, detailed clinical histories were available and showed that three individuals had a clinical course predominantly characterized by epilepsy, whereas the other seven individuals had progressive cognitive, behavioral, and motor decline, in addition to epilepsy. The main neuropathologic findings included: tau pathology (16/16 cases), cerebellar degeneration (11/16 cases), and white matter degeneration (7/16 cases). The tau pathology was characterized by filamentous tau-positive deposits in the form of neurofibrillary tangles, pre-tangles, and dot-like grains and threads in the neuropil. All cases showed some degree of tau pathology in the neocortex and the locus coeruleus with frequent involvement of the substantia nigra, tegmental nuclei, and lesser involvement of other grey matter sites, but there was a lack of glial tau pathology. The tau pathology in the neocortex showed a multifocal superficial laminar pattern. We conclude that nodding syndrome is a clinicopathological entity associated consistently with tau pathology, but our observations did not establish the cause of the disease or an explanation for the tau pathology.

A 59-year-old man with a history of cerebral palsy and dextroscoliosis died in a group home. He required supplemental oxygen and had no bowel movement for weeks prior to death. At autopsy, the abdomen was markedly distended and there were flexion contractures of the legs. Postmortem computed tomography revealed a dilated digestive tract and fecal loading in the sigmoid and rectum, marked upwardly displaced diaphragm and scoliosis. On internal examination, the diaphragm was displaced rostrally and the rectosigmoid colon contained 2.5 kg of fecaloma with two rectal fecaliths. Severe scoliosis with marked reduction in volume of thoracic cavity was present. Microscopic examination revealed chronic aspiration pneumonia and chronic pulmonary hypertension. Overall, four factors led to respiratory failure: fecaloma; cerebral palsy; scoliosis; and chronic aspiration pneumonia. Based on clinicopathological correlation, the cause of death was determined to be a combination of these factors, and the key acute factor was the fecaloma.

Nodding syndrome is an enigmatic recurrent epidemic neurologic disease that affects children in East Africa. The illness begins with vertical nodding of the head and can progress to grand mal seizures and death after several years. The most recent outbreak of nodding syndrome occurred in northern Uganda. We now describe the clinicopathologic spectrum of nodding syndrome in northern Uganda. The neuropathologic findings of 16 children or young adults with fatal nodding syndrome were correlated with the onset, duration and progression of their neurological illness. The affected individuals ranged in age from 14 to 25 years at the time of death with a duration of illness ranging from 6–15 years. All 16 cases had chronic seizures. In ten cases, detailed clinical histories were available and showed that three individuals had a clinical course that was predominantly characterized by epilepsy whereas the other seven individuals had progressive cognitive, behavioural and motor decline, in addition to epilepsy. The main neuropathologic findings included: tau pathology (16/16 cases), cerebellar degeneration (11/16 cases), and white matter degeneration (7/16 cases). The tau pathology was characterized by filamentous tau-positive deposits in the form of neurofibrillary tangles, pre-tangles, and dot-like grains and threads in the neuropil. All cases showed some degree of tau pathology in the neocortex and in the locus coeruleus with frequent involvement of the substantia nigra and tegmental nuclei and lesser involvement of other grey matter sites, but there was a lack of glial tau pathology. The tau pathology in the neocortex showed a multifocal superficial laminar pattern. We conclude that nodding syndrome is a clinicopathological entity associated consistently with tau pathology, but our observations did not establish the cause of the disease, or an explanation for the tau pathology.

Safe and effective vaccines are needed to end the COVID-19 pandemic caused by SARS-CoV-2. Here we report the preclinical development of a lipid nanoparticle (LNP) formulated SARS-CoV-2 mRNA vaccine, PTX-COVID19-B. PTX-COVID19-B was chosen among three candidates after the initial mouse vaccination results showed that it elicited the strongest neutralizing antibody response against SARS-CoV-2. Further tests in mice and hamsters indicated that PTX-COVID19-B induced robust humoral and cellular immune responses and completely protected the vaccinated animals from SARS-CoV-2 infection in the lung. Studies in hamsters also showed that PTX-COVID19-B protected the upper respiratory tract from SARS-CoV-2 infection. Mouse immune sera elicited by PTX-COVID19-B vaccination were able to neutralize SARS-CoV-2 variants of concern (VOCs), including the B.1.1.7, B.1.351 and P.1 lineages. No adverse effects were induced by PTX-COVID19-B in both mice and hamsters. These preclinical results indicate that PTX-COVID19-B is safe and effective. Based on these results, PTX-COVID19-B was authorized by Health Canada to enter clinical trials in December 2020 with a phase 1 clinical trial ongoing ( ClinicalTrials.gov number: NCT04765436 ). One Sentence Summary PTX-COVID19-B is a SARS-CoV-2 mRNA vaccine that is highly immunogenic, safe, and effective in preventing SARS-CoV-2 infection in mice and hamsters and is currently being evaluated in human clinical trials.