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Background: CHI3L1 (YKL-40) is up-regulated in a variety of inflammatory conditions and cancers. We have previously reported elevated CHI3L1 concentration in the cerebrospinal fluid (CSF) of human and non-human primates with lentiviral encephalitis and using immunohistochemistry showed that CHI3L1 was associated with astrocytes.Methods: In the current study CHI3L1 transcription and expression were evaluated in a variety of acute and chronic human neurological diseases.Results: ELISA revealed significant elevation of CHI3L1 in the CSF of multiple sclerosis (MS) patients as well as mild elevation with aging. In situ hybridization (ISH) showed CHI3L1 transcription mostly associated with reactive astrocytes, that was more pronounced in inflammatory conditions like lentiviral encephalitis and MS. Comparison of CHI3L1 expression in different stages of brain infarction showed that YKL40 was abundantly expressed in astrocytes during acute phases and diminished to low levels in chronic infarcts.Conclusions: Taken together, these findings demonstrate that CHI3L1 is induced in astrocytes in a variety of neurological diseases but that it is most abundantly associated with astrocytes in regions of inflammatory cells. [ABSTRACT FROM AUTHOR]

Chronic inflammation is frequently invoked as a mechanism of neurodegeneration and yet inflammatory cell infiltrates are seldom seen in brains of these disorders. Different disciplines utilize different technologies and methodologies to describe what is immunologically defined as the innate immune response (IIR). We examined murine models of the human neurodegenerative disease Aicardi-Goutières Syndrome, where an IIR is initiated by aberrant RNA metabolism secondary to a mutation in adenosine deaminase acting on RNA gene (ADAR1). We previously showed that these mice demonstrated a deficit in RNA editing that lead to MDA-5 mediated RNA sensing pathway activation of the IIR with massive interferon stimulated gene transcription and translation. As early as 2 weeks of age, in situ hybridization demonstrated that different central nervous system (CNS) cell lineages expressed very high levels of distinct interferon stimulated genes (ISGs) in the absence of interferon and absence of immune cell infiltrates. We have expanded these studies to more completely describe the breadth of ISG expression systemically and in CNS using double label in situ hybridization. Within the CNS aberrant ISG expression was mostly limited to neurons, microglia, ependyma, choroid plexus, and endothelial cells with little expression in oligodendroglia and astrocytes except for STAT1. Wild type controls showed a similar pattern of ISG expression but only in aged mice and at levels minimally detectable by in situ hybridization. Despite months of elevated ISG expression in mutant mice, there was essentially no inflammatory infiltrate, no interferon production and minimal glial reaction. Histomorphological neurodegenerative pathology of ventricular dilatation and deep gray matter mineralization were evident in mutant mice 8-13 months of age but this did not show a spatial relationship to ISG expression. This IIR without immune cell infiltration leads to neurodegeneration through non-canonical pathways that may accentuate normal aging pathways., (© 2022 The Authors. Brain Pathology published by John Wiley & Sons Ltd on behalf of International Society of Neuropathology.)

Molecular profiling studies have shown that 85% of canine urothelial carcinomas (UC) harbor an activating BRAF V595E mutation, which is orthologous to the V600E variant found in several human cancer subtypes. In dogs, this mutation provides both a powerful diagnostic marker and a potential therapeutic target; however, due to their relative infrequency, the remaining 15% of cases remain understudied at the molecular level. We performed whole exome sequencing analysis of 28 canine urine sediments exhibiting the characteristic DNA copy number signatures of canine UC, in which the BRAF V595E mutation was undetected (UDV595E specimens). Among these we identified 13 specimens (46%) harboring short in-frame deletions within either BRAF exon 12 (7/28 cases) or MAP2K1 exons 2 or 3 (6/28 cases). Orthologous variants occur in several human cancer subtypes and confer structural changes to the protein product that are predictive of response to different classes of small molecule MAPK pathway inhibitors. DNA damage response and repair genes, and chromatin modifiers were also recurrently mutated in UDV595E specimens, as were genes that are positive predictors of immunotherapy response in human cancers. Our findings suggest that short in-frame deletions within BRAF exon 12 and MAP2K1 exons 2 and 3 in UDV595E cases are alternative MAPK-pathway activating events that may have significant therapeutic implications for selecting first-line treatment for canine UC. We developed a simple, cost-effective capillary electrophoresis genotyping assay for detection of these deletions in parallel with the BRAF V595E mutation. The identification of these deletion events in dogs offers a compelling cross-species platform in which to study the relationship between somatic alteration, protein conformation, and therapeutic sensitivity., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Thomas et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Aicardi-Goutières syndrome (AGS) is a severe neurodegenerative disease with clinical features of early-onset encephalopathy and progressive loss of intellectual abilities and motor control. Gene mutations in seven protein-coding genes have been found to be associated with AGS. However, the causative role of these mutations in the early-onset neuropathogenesis has not been demonstrated in animal models, and the mechanism of neurodegeneration of AGS remains ambiguous., Methods: Via CRISPR/Cas-9 technology, we established a mutant mouse model in which a genetic mutation found in AGS patients at the ADAR1 coding gene (Adar) loci was introduced into the mouse genome. A mouse model carrying double gene mutations encoding ADAR1 and MDA-5 was prepared using a breeding strategy. Phenotype, gene expression, RNA sequencing, innate immune pathway activation, and pathologic studies including RNA in situ hybridization (ISH) and immunohistochemistry were used for characterization of the mouse models to determine potential disease mechanisms., Results: We established a mouse model bearing a mutation in the catalytic domain of ADAR1, the D1113H mutation found in AGS patients. With this mouse model, we demonstrated a causative role of this mutation for the early-onset brain injuries in AGS and determined the signaling pathway underlying the neuropathogenesis. First, this mutation altered the RNA editing profile in neural transcripts and led to robust IFN-stimulated gene (ISG) expression in the brain. By ISH, the brains of mutant mice showed an unusual, multifocal increased expression of ISGs that was cell-type dependent. Early-onset astrocytosis and microgliosis and later stage calcification in the deep white matter areas were observed in the mutant mice. Brain ISG activation and neuroglial reaction were completely prevented in the Adar D1113H mutant mice by blocking RNA sensing through deletion of the cytosolic RNA receptor MDA-5., Conclusions: The Adar D1113H mutation in the ADAR1 catalytic domain results in early-onset and MDA5-dependent encephalopathy with IFN pathway activation in the mouse brain., (© 2022. The Author(s).)

Objective: To compare urine concentrations of fibrinogen (uFIB) and interleukin-6 (uIL-6) between dogs with risk factors for enterococcal bacteriuria and healthy dogs., Sample: Banked urine samples with negative aerobic culture results from 8 dogs with urolithiasis, 9 dogs with anatomic abnormalities of the lower portion of the urinary tract (LUT), 10 dogs with LUT neoplasia, and 21 healthy control dogs., Procedures: Urine creatinine concentration (uCrea) was determined by an automated biochemical analyzer, and uFIB and uIL-6 were determined by dog-specific ELISAs. The uFIB:uCrea and uIL-6:uCrea ratios were calculated for each sample to normalize intersample differences in urine concentration and were compared among the 4 experimental groups., Results: Median uFIB:uCrea ratios for dogs with urolithiasis (0.72; interquartile [25th to 75 percentile] range [IQR], 0.46 to 3.48) and LUT neoplasia (6.16; IQR, 3.89 to 12.75), but not for dogs with LUT anatomic abnormalities (0.48; IQR, 0.27 to 0.69), were significantly greater than that for control dogs (0.17; IQR, 0.07 to 0.39). Median uIL-6: uCrea ratios for dogs with urolithiasis (0.48; IQR, 0.18 to 1.61), LUT anatomic abnormalities (0.25; IQR, 0.17 to 0.33), and LUT neoplasia (0.25; IQR, 0.12 to 1.01) were significantly greater than that for control dogs (0.08; IQR, 0.06 to 0.11)., Conclusions and Clinical Relevance: The uFIB and uIL-6 in dogs with risk factors for enterococcal bacteriuria were generally greater than corresponding values in control dogs. Further investigation is necessary to determine the role of fibrinogen in enterococcal colonization of the urinary tract of dogs.

Background: Aicardi-Goutières syndrome (AGS) is a severe infant or juvenile-onset autoimmune disease characterized by inflammatory encephalopathy with an elevated type 1 interferon-stimulated gene (ISG) expression signature in the brain. Mutations in seven different protein-coding genes, all linked to DNA/RNA metabolism or sensing, have been identified in AGS patients, but none of them has been demonstrated to activate the IFN pathway in the brain of an animal. The molecular mechanism of inflammatory encephalopathy in AGS has not been well defined. Adenosine Deaminase Acting on RNA 1 (ADAR1) is one of the AGS-associated genes. It carries out A-to-I RNA editing that converts adenosine to inosine at double-stranded RNA regions. Whether an AGS-associated mutation in ADAR1 activates the IFN pathway and causes autoimmune pathogenesis in the brain is yet to be determined., Methods: Mutations in the ADAR1 gene found in AGS patients were introduced into the mouse genome via CRISPR/Cas9 technology. Molecular activities of the specific p.K999N mutation were investigated by measuring the RNA editing levels in brain mRNA substrates of ADAR1 through RNA sequencing analysis. IFN pathway activation in the brain was assessed by measuring ISG expression at the mRNA and protein level through real-time RT-PCR and Luminex assays, respectively. The locations in the brain and neural cell types that express ISGs were determined by RNA in situ hybridization (ISH). Potential AGS-related brain morphologic changes were assessed with immunohistological analysis. Von Kossa and Luxol Fast Blue staining was performed on brain tissue to assess calcification and myelin, respectively., Results: Mice bearing the ADAR1 p.K999N were viable though smaller than wild type sibs. RNA sequencing analysis of neuron-specific RNA substrates revealed altered RNA editing activities of the mutant ADAR1 protein. Mutant mice exhibited dramatically elevated levels of multiple ISGs within the brain. RNA ISH of brain sections showed selective activation of ISG expression in neurons and microglia in a patchy pattern. ISG-15 mRNA was upregulated in ADAR1 mutant brain neurons whereas CXCL10 mRNA was elevated in adjacent astroglia. No calcification or gliosis was detected in the mutant brain., Conclusions: We demonstrated that an AGS-associated mutation in ADAR1, specifically the p.K999N mutation, activates the IFN pathway in the mouse brain. The ADAR1 p.K999N mutant mouse replicates aspects of the brain interferonopathy of AGS. Neurons and microglia express different ISGs. Basal ganglia calcification and leukodystrophy seen in AGS patients were not observed in K999N mutant mice, indicating that development of the full clinical phenotype may need an additional stimulus besides AGS mutations. This mutant mouse presents a robust tool for the investigation of AGS and neuroinflammatory diseases including the modeling of potential "second hits" that enable severe phenotypes of clinically variable diseases., (© 2021. The Author(s).)

Objective: Cerebral arteriovenous malformations (AVMs) are rare cerebral vascular lesions that are associated with high morbidity and mortality from hemorrhage; however, stereotactic radiosurgery (SRS) is a well-validated treatment modality. Few reports have delineated a subgroup of patients who develop delayed chronic encapsulated expanding hematomas (CEEHs) despite angiographic evidence of AVM obliteration following radiosurgery. In this report, the authors performed a retrospective review of more than 1000 radiosurgically treated intracranial AVM cases to delineate the incidence and management of this rare entity., Methods: Between 1988 and 2019, 1010 patients with intracranial AVM underwent Gamma Knife SRS at the University of Pittsburgh Medical Center. In addition to a review of a prospective institutional database, the authors performed a retrospective chart review of the departmental AVM database to specifically identify patients with CEEH. Pertinent clinical and radiological characteristics as well as patient outcomes were recorded and analyzed., Results: Nine hundred fifty patients with intracranial AVM (94%) had sufficient clinical follow-up for analysis. Of these, 6 patients with CEEH underwent delayed resection (incidence rate of 0.0045 event per person-year). These patients included 4 males and 2 females with a mean age of 45.3 ± 13.8 years at the time of initial SRS. Four patients had smaller AVM volumes (4.9-10 cm3), and 3 of them were treated with a single SRS procedure. Two patients had larger-volume AVMs (55 and 56 cm3), and both underwent multimodal management that included staged SRS and embolization. Time to initial recognition of the CEEH after initial SRS ranged between 66 and 243 months. The time between CEEH recognition and resection ranged from 2 to 9 months. Resection was required because of progressive neurological symptoms that correlated with imaging evidence of gradual hematoma expansion. All 6 patients had angiographically confirmed obliteration of their AVM. Pathology revealed a mixed chronicity hematoma with areas of fibrosed blood vessels and rare areas of neovascularization with immature blood vessels but no evidence of a persistent AVM. All 6 patients reported persistent clinical improvement after hematoma resection., Conclusions: CEEH after SRS for AVM is a rare complication with an incidence rate of 0.0045 event per person-year over the authors' 30-year experience. When clinical symptoms progress and imaging reveals progressive enlargement over time, complete resection of a CEEH results in significant clinical recovery. Knowledge of this rare entity facilitates timely detection and eventual surgical intervention to achieve optimal outcomes.

For the past 400 years, the most common cause of dementia was tertiary syphilis [1]. Its prevalence declined dramatically with the advent of potent antibiotics in the 20 th century, but these same antibiotics also helped increase our average lifespan, leading to dramatic increases in the prevalence of age-related dementias. Abundant progress has been made connecting early onset dementias with mutations in neural genes. Late onset dementias have been linked to a more enigmatic set of genes, some of which have been connected to neuroinflammation, begging the question: Are age-related dementias linked to infection? Numerous studies have reported an association between dementia and infections in general and viral infections in particular. While these associations have been subject to extensive reviews, the purpose of this synthesis is to examine the hypothesized link of viral infections and dementia from the opposite perspective: What do we know about acute and chronic encephalitides that could forge a link with dementias? There appears to be little support for the concept that viral infections are a major contributor to today's common dementias. However, the emergence of new central nervous system (CNS) viral infections, coupled with senescent immune and nervous systems in our aged population, create new opportunities for infections to contribute to dementia.

Neurotoxic side effects of traditional systemic chemotherapy are abundantly described. The introduction of newly developed biologic therapeutics and cellular immune effector therapies has expanded the spectrum of neurotoxicity. Multifocal necrotizing leukoencephalopathy (MNL) is a pathologic condition of unknown etiology that has been observed in patients after prolonged critical illness. We observed a case of MNL in a patient treated with extensive multimodal therapy including chimeric antigen receptor T cells. A month before death, MRI demonstrated signs of inflammation and developing edema in brainstem structures. At autopsy the abnormal MRI regions showed a wave-like loss of microglia with hemorrhagic MNL in regions closest to the brain surface. These findings reiterate the susceptibility of white matter to antineoplastic therapy and suggest new mechanisms of neurotoxicity when traditional chemotherapy is combined with biologic or cellular effector therapy., (© 2020 American Association of Neuropathologists, Inc. All rights reserved.)

Biological evolution of the microbiome continually drives the emergence of human viral pathogens, a subset of which attack the nervous system. The sheer number of pathogens that have appeared, along with their abundance in the environment, demand our attention. For the most part, our innate and adaptive immune systems have successfully protected us from infection; however, in the past 5 decades, through pathogen mutation and ecosystem disruption, a dozen viruses emerged to cause significant neurologic disease. Most of these pathogens have come from sylvatic reservoirs having made the energetically difficult, and fortuitously rare, jump into humans. But the human microbiome is also replete with agents already adapted to the host that need only minor mutations to create neurotropic/toxic agents. While each host/virus symbiosis is unique, this review examines virologic and immunologic principles that govern the pathogenesis of different viral CNS infections that were described in the past 50 years (Influenza, West Nile Virus, Zika, Rift Valley Fever Virus, Hendra/Nipah, Enterovirus-A71/-D68, Human parechovirus, HIV, and SARS-CoV). Knowledge of these pathogens provides us the opportunity to respond and mitigate infection while at the same time prepare for inevitable arrival of unknown agents., (© 2020 American Association of Neuropathologists, Inc. All rights reserved.)

Introduction: Documentation of histologic findings associated with congenital hydrocephalus in the fetal lamb model is a critical step in evaluating the efficacy of ventriculoamniotic shunting in the human fetus., Methods: Four fetal sheep had hydrocephalus induced at approximately 95 days' gestation. Two co-twins remained as controls. The ewes were euthanized at term. The lamb brains were fixed in formalin, paraffin-embedded, stained, and analyzed for markers of neuropathology. Astrocytosis, microgliosis, and axonal loss were assessed with immunocytochemistry for glial fibrillary acidic protein, ionized calcium-binding adapter, and neurofilament/amyloid precursor protein, respectively. Cortical gray matter extracellular matrix was assessed with staining for the lectin Wisteria Floribunda agglutinin., Results: Hydrocephalic lamb brains demonstrated deep white matter damage with loss of projecting axonal tracts in regions physically distorted by hydrocephalus, similar to that seen in hydrocephalic humans. There was no evidence of abnormal neocortical neuronal migration; however, there was evidence for delayed maturation of the neocortical gray matter, possibly from increased intracerebral pressure and subsequent ischemia. Control lamb brains demonstrated none of the above findings., Conclusion: This histological approach can be used to further define the mechanism of brain damage associated with hydrocephalus and interpret the efficacy of ventriculoamniotic shunting on fetal lamb brain neuroanatomy., (© 2019 S. Karger AG, Basel.)

Influenza virus infection causes a spectrum of diseases, ranging from mild upper respiratory tract infection to severe lower respiratory tract infection, that can lead to diffuse alveolar damage, interstitial and airspace inflammation, or acute respiratory failure. Mechanisms instructing disease severity are not completely understood, but host, viral, and bacterial factors influence disease outcome. With age being one host factor associated with a higher risk of severe influenza, we investigated regional pulmonary distribution and severity of pneumonia after 2009 H1N1 influenza virus infection in newly weaned, adult, and aged ferrets to better understand age-dependent susceptibility and pathology. Aged ferrets exhibited greater weight loss and higher rates of mortality than adult ferrets, whereas most newly weaned ferrets did not lose weight but had a lack of weight gain. Newly weaned ferrets exhibited minimal pneumonia, whereas adult and aged ferrets had a spectrum of pneumonia severity. Influenza virus-induced pneumonia peaked earliest in adult ferrets, whereas aged ferrets had delayed presentation. Bronchial severity differed among groups, but bronchial pathology was comparable among all cohorts. Alveolar infection was strikingly different among groups. Newly weaned ferrets had little alveolar cell infection. Adult and aged ferrets had alveolar infection, but aged ferrets were unable to clear infection. These different age-related pneumonia and infection patterns suggest therapeutic strategies to treat influenza should be tailored contingent on age., (Copyright © 2019 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Background and Purpose: Identification of mesial temporal sclerosis is critical in the evaluation of individuals with temporal lobe epilepsy. Our aim was to assess the performance of FDA-approved software measures of hippocampal volume to identify mesial temporal sclerosis in patients with medically refractory temporal lobe epilepsy compared with the initial clinical interpretation of a neuroradiologist., Materials and Methods: Preoperative MRIs of 75 consecutive patients who underwent a temporal resection for temporal lobe epilepsy from 2011 to 2016 were retrospectively reviewed, and 71 were analyzed using Neuroreader, a commercially available automated segmentation and volumetric analysis package. Volume measures, including hippocampal volume as a percentage of total intracranial volume and the Neuroreader Index, were calculated. Radiologic interpretations of the MR imaging and pathology from subsequent resections were classified as either mesial temporal sclerosis or other, including normal findings. These measures of hippocampal volume were evaluated by receiver operating characteristic curves on the basis of pathologic confirmation of mesial temporal sclerosis in the resected temporal lobe. Sensitivity and specificity were calculated for each method and compared by means of the McNemar test using the optimal threshold as determined by the Youden J point., Results: Optimized thresholds of hippocampal percentage of a structural volume relative to total intracranial volume (<0.19%) and the Neuroreader Index (≤-3.8) were selected to optimize sensitivity and specificity (89%/71% and 89%/78%, respectively) for the identification of mesial temporal sclerosis in temporal lobe epilepsy compared with the initial clinical interpretation of the neuroradiologist (50% and 87%). Automated measures of hippocampal volume predicted mesial temporal sclerosis more accurately than radiologic interpretation (McNemar test, P < .0001)., Conclusions: Commercially available automated segmentation and volume analysis of the hippocampus accurately identifies mesial temporal sclerosis and performs significantly better than the interpretation of the radiologist., (© 2019 by American Journal of Neuroradiology.)

Aging in later life engenders numerous changes to the cerebral microvasculature. Such changes can remain clinically silent but are associated with greater risk for negative health outcomes over time. Knowledge is limited about the pathogenesis, prevention, and treatment of potentially detrimental changes in the cerebral microvasculature that occur with advancing age. In this review, we summarize literature on aging of the cerebral microvasculature, and we propose a conceptual framework to fill existing research gaps and advance future work on this heterogeneous phenomenon. We propose that the major gaps in this area are attributable to an incomplete characterization of cerebrovascular pathology, the populations being studied, and the temporality of exposure to risk factors. Specifically, currently available measures of age-related cerebral microvasculature changes are indirect, primarily related to parenchymal damage rather than direct quantification of small vessel damage, limiting the understanding of cerebral small vessel disease (cSVD) itself. Moreover, studies seldom account for variability in the health-related conditions or interactions with risk factors, which are likely determinants of cSVD pathogenesis. Finally, study designs are predominantly cross-sectional and/or have relied on single time point measures, leaving no clear evidence of time trajectories of risk factors or of change in cerebral microvasculature. We argue that more resources should be invested in 1) developing methodological approaches and basic science models to better understand the pathogenic and etiological nature of age-related brain microvascular diseases and 2) implementing state-of-the-science population study designs that account for the temporal evolution of cerebral microvascular changes in diverse populations across the lifespan.

During the Zika epidemic in Brazil, a baby was born at term with microcephaly and arthrogryposis. The mother had Zika symptoms at 10 weeks of gestation. At 17 weeks, ultrasound showed cerebral malformation and ventriculomegaly. At 24 weeks, the amniotic fluid contained ZIKV RNA and at birth, placenta and maternal blood were also positive using RT-qPCR. At birth the baby urine contained ZIKV RNA, whereas CSF at birth and urine at 17 days did not. Seizures started at 6 days. EEG was abnormal and CT scan showed cerebral atrophy, calcifications, lissencephaly, ventriculomegaly, and cerebellar hypoplasia. Bacterial sepsis at 2 months was treated. A sudden increase in head circumference occurred at 4 months necessitating ventricle-peritoneal shunt placement. At 5 months, the infant died with sepsis due to bacterial meningitis. Neuropathological findings were as severe as some of those found in neonates who died soon after birth, including hydrocephalus, destructive lesions/calcification, gliosis, abnormal neuronal migration, dysmaturation of nerve cells, hypomyelination, loss of descending axons, and spinal motor neurons. ZIKV RNA was detected only in frozen brain tissue using RT-qPCR, but infected cells were not detected by in situ hybridization. Progressive gliosis and microgliosis in the midbrain may have contributed to aqueduct compression and subsequent hydrocephalus. The etiology of progressive disease after in utero infection is not clear and requires investigation., (© 2018 American Association of Neuropathologists, Inc. All rights reserved.)

Background: Damage to the central nervous system during HIV infection can lead to variable neurobehavioral dysfunction termed HIV-associated neurocognitive disorders (HAND). There is no clear consensus regarding the neuropathological or cellular basis of HAND. We sought to study the potential contribution of aging to the pathogenesis of HAND. Aged (range = 14.7-24.8 year) rhesus macaques of Chinese origin (RM-Ch) (n = 23) were trained to perform cognitive tasks. Macaques were then divided into four groups to assess the impact of SIVmac251 infection (n = 12) and combined antiretroviral therapy (CART) (5 infected; 5 mock-infected) on the execution of these tasks., Results: Aged SIV-infected RM-Ch demonstrated significant plasma viremia and modest CSF viral loads but showed few clinical signs, no elevations of systemic temperature, and no changes in activity levels, platelet counts or weight. Concentrations of biomarkers of acute and chronic inflammation such as soluble CD14, CXCL10, IL-6 and TNF-α are known to be elevated following SIV infection of young adult macaques of several species, but concentrations of these biomarkers did not shift after SIV infection in aged RM-Ch and remained similar to mock-infected macaques. Neither acute nor chronic SIV infection or CART had a significant impact on accuracy, speed or percent completion in a sensorimotor test., Conclusions: Viremia in the absence of a chronic elevated inflammatory response seen in some aged RM-Ch is reminiscent of SIV infection in natural disease resistant hosts. The absence of cognitive impairment during SIV infection in aged RM-Ch might be in part attributed to diminishment of some facets of the immunological response. Additional study encompassing species and age differences is necessary to substantiate this hypothesis.

The recent epidemic of West Nile Virus (WNV) infection in the United States was associated with severe neurological disease in immunocompromised hosts, while the emergence of Zika virus infection in the Americas has been notable for an association with increased microcephaly in the fetuses of infected mothers. Rare autopsies of WNV infected humans have shown multiple organ involvement with a clear neurotropism. We have recently had the opportunity to examine the distribution of Zika virus in autopsies of newborns from infected pregnancies. While both viruses infect multiple organs, Zika appears to cause neurological disease in the fetus through two different mechanisms. Infection during the first trimester showed the potential to infect neural progenitor cells causing severe developmental abnormalities, while infection later in gestation was associated with meningeal infection and destructive ischemic lesions of the brain. Both viruses infect kidney tubules but Zika shares a prominent hepatotropism characteristic of other flaviviruses (e.g., Dengue). Limited transplacental Zika infection would be consistent with restriction to primary maternal infections with high viremia. In the absence of a vaccine, restriction of travel by immunosuppressed and pregnant non-immune individuals to endemic regions seems prudent., (© 2017 Japanese Society of Neuropathology.)

A major concern associated with ZIKV infection is the increased incidence of microcephaly with frequent calcifications in infants born from infected mothers. To date, postmortem analysis of the central nervous system (CNS) in congenital infection is limited to individual reports or small series. We report a comprehensive neuropathological study in ten newborn babies infected with ZIKV during pregnancy, including the spinal cords and dorsal root ganglia (DRG), and also muscle, pituitaries, eye, systemic organs, and placentas. Using in situ hybridization (ISH) and electron microscopy, we investigated the role of direct viral infection in the pathogenesis of the lesions. Nine women had Zika symptoms between the 4th and 18th and one in the 28th gestational week. Two babies were born at 32, one at 34 and 36 weeks each and six at term. The cephalic perimeter was reduced in four, and normal or enlarged in six patients, although the brain weights were lower than expected. All had arthrogryposis, except the patient infected at 28 weeks gestation. We defined three patterns of CNS lesions, with different patterns of destructive, calcification, hypoplasia, and migration disturbances. Ventriculomegaly was severe in the first pattern due to midbrain damage with aqueduct stenosis/distortion. The second pattern had small brains and mild/moderate (ex-vacuo) ventriculomegaly. The third pattern, a well-formed brain with mild calcification, coincided with late infection. The absence of descending fibres resulted in hypoplastic basis pontis, pyramids, and cortico-spinal tracts. Spinal motor cell loss explained the intrauterine akinesia, arthrogryposis, and neurogenic muscle atrophy. DRG, dorsal nerve roots, and columns were normal. Lympho-histiocytic inflammation was mild. ISH showed meningeal, germinal matrix, and neocortical infection, consistent with neural progenitors death leading to proliferation and migration disorders. A secondary ischemic process may explain the destructive lesions. In conclusion, we characterized the destructive and malformative consequences of ZIKV in the nervous system, as reflected in the topography and severity of lesions, anatomic localization of the virus, and timing of infection during gestation. Our findings indicate a developmental vulnerability of the immature CNS, and shed light on possible mechanisms of brain injury of this newly recognized public health threat.

[This corrects the article DOI: 10.1371/journal.ppat.1006219.].

Zika virus (ZIKV), an emerging flavivirus, has recently spread explosively through the Western hemisphere. In addition to symptoms including fever, rash, arthralgia, and conjunctivitis, ZIKV infection of pregnant women can cause microcephaly and other developmental abnormalities in the fetus. We report herein the results of ZIKV infection of adult rhesus macaques. Following subcutaneous infection, animals developed transient plasma viremia and viruria from 1-7 days post infection (dpi) that was accompanied by the development of a rash, fever and conjunctivitis. Animals produced a robust adaptive immune response to ZIKV, although systemic cytokine response was minimal. At 7 dpi, virus was detected in peripheral nervous tissue, multiple lymphoid tissues, joints, and the uterus of the necropsied animals. Notably, viral RNA persisted in neuronal, lymphoid and joint/muscle tissues and the male and female reproductive tissues through 28 to 35 dpi. The tropism and persistence of ZIKV in the peripheral nerves and reproductive tract may provide a mechanism of subsequent neuropathogenesis and sexual transmission.

Human infections with highly pathogenic avian influenza A (H5N1) virus are frequently fatal but the mechanisms of disease remain ill-defined. H5N1 infection is associated with intense production of proinflammatory cytokines, but whether this cytokine storm is the main cause of fatality or is a consequence of extensive virus replication that itself drives disease remains controversial. Conventional intratracheal inoculation of a liquid suspension of H5N1 influenza virus in nonhuman primates likely results in efficient clearance of virus within the upper respiratory tract and rarely produces severe disease. We reasoned that small particle aerosols of virus would penetrate the lower respiratory tract and blanket alveoli where target cells reside. We show that inhalation of aerosolized H5N1 influenza virus in cynomolgus macaques results in fulminant pneumonia that rapidly progresses to acute respiratory distress syndrome with a fatal outcome reminiscent of human disease. Molecular imaging revealed intense lung inflammation coincident with massive increases in proinflammatory proteins and IFN-α in distal airways. Aerosolized H5N1 exposure decimated alveolar macrophages, which were widely infected and caused marked influx of interstitial macrophages and neutrophils. Extensive infection of alveolar epithelial cells caused apoptosis and leakage of albumin into airways, reflecting loss of epithelial barrier function. These data establish inhalation of aerosolized virus as a critical source of exposure for fatal human infection and reveal that direct viral effects in alveoli mediate H5N1 disease. This new nonhuman primate model will advance vaccine and therapeutic approaches to prevent and treat human disease caused by highly pathogenic avian influenza viruses., (Copyright © 2017 by The American Association of Immunologists, Inc.)

We used controlled cortical impact in mice to model human traumatic brain injury (TBI). Local injury was accompanied by distal diaschisis lesions that developed within brain regions anatomically connected to the injured cortex. At 7 days after injury, histochemistry documented broadly distributed lesions, particularly in the contralateral cortex and ipsilateral thalamus and striatum. Reactive astrocytosis and microgliosis were noted in multiple neural pathways that also showed silver-stained cell processes and bodies. Wisteria floribunda agglutinin (WFA) staining, a marker of perineuronal nets, was substantially diminished in the ipsilateral, but less so in the contralateral cortex. Contralateral cortical silver positive diaschisis lesions showed loss of both phosphorylated and unphosphorylated neurofilament staining, but overall preservation of microtubule-associated protein (MAP)-2 staining. Thalamic lesions showed substantial loss of MAP-2 and unphosphorylated neurofilaments in addition to moderate loss of phosphorylated neurofilament. One animal demonstrated contralateral cerebellar degeneration at 7 days post-injury. After 21 days, the gliosis had quelled, however persistent silver staining was noted. Using a novel serial section technique, we were able to perform electron microscopy on regions fully characterized at the light microscopy level. Cell bodies and processes that were silver positive at the light microscopy level showed hydropic disintegration consisting of: loss of nuclear heterochromatin; dilated somal and neuritic processes with a paucity of filaments, tubules, and mitochondria; and increased numbers of electron-dense membranous structures. Importantly the cell membrane itself was still intact 3 weeks after injury. Although the full biochemical nature of these lesions remains to be deciphered, the morphological preservation of damaged neurons and processes raises the question of whether this is a reversible process., Competing Interests: Author Disclosure Statement No competing financial interests exist.

Small changes in the electron donating ability of coordinating groups have substantial effects on the multicomponent self-assembly of Fe (II)-iminopyridine-based meso-helicate complexes. Both the nature of the internal diamine core and the terminal formylpyridine reactants control the rate of the assembly process, the thermodynamic favorability of the meso-helicate products, and the selective incorporation of different aldehyde termini into the assembly. Steric congestion at the coordinating ligands can prevent assembly altogether, and favorable incorporation of electron-rich aldehyde termini is observed, even though the rate of reaction is accelerated by the use of electron-poor aldehyde reactants. NMR and electrospray ionization mass spectrometry analyses were employed to determine the synergistic nature of narcissistic self-sorting in this system, which depends on both the rigidity of the central core and the electronic donor ability of the aldehyde terminus. These experiments illustrate that significant control of self-sorting and self-assembly is possible upon extremely small variations in ligand structure, rigidity, and donor ability.

Respiratory syncytial virus (RSV) is a significant cause of lower respiratory tract infections resulting in bronchiolitis and even mortality in the elderly and young children/infants. Despite the impact of this virus on human health, no licensed vaccine exists. Unlike many other viral infections, RSV infection or vaccination does not induce durable protective antibodies in humans. In order to elicit high titer, neutralizing antibodies against RSV, we investigated the use of the adjuvant Advax™, a novel polysaccharide adjuvant based on delta inulin microparticles, to enhance antibody titers following vaccination. BALB/c mice were vaccinated intramuscularly with live RSV as a vaccine antigen in combination with one of two formulations of Advax™. Advax-1 was comprised of the standard delta inulin adjuvant and Advax-2 was formulated delta inulin plus CpG oligodendronucleotides (ODNs). An additional group of mice were either mock vaccinated, immunized with vaccine only, or administered vaccine plus Imject Alum. Following 3 vaccinations, mice had neutralizing antibody titers that correlated with reduction in viral titers in the lungs. Advax-1 significantly enhanced serum RSV-specific IgG1 levels at week 6 indicative of a Th2 response, similar to titers in mice administered vaccine plus Imject Alum. In contrast, mice vaccinated with vaccine plus Advax-2 had predominately IgG2a titers indicative of a Th1 response that was maintained during the entire study. Interestingly, regardless of which Advax TM adjuvant was used, the neutralizing titers were similar between groups, but the viral lung titers were significantly lower (∼10E+3pfu/g) in mice administered vaccine with either Advax TM adjuvant compared to mice administered adjuvants only. The lung pathology in vaccinated mice with Advax TM was similar to Imject Alum. Overall, RSV vaccine formulated with Advax TM had high neutralizing antibody titers with low lung viral titers, but exacerbated lung pathology compared to unvaccinated mice.

Antiretroviral therapy has led to increased survival of HIV-infected patients but also increased prevalence of HIV-associated neurocognitive disorders. We previously identified YKL40 as a potential cerebrospinal fluid (CSF) biomarker of lentiviral central nervous system (CNS) disease in HIV-infected patients and in the macaque model of HIV encephalitis. The aim of this study was to define the specificity and sensitivity along with the predictive value of YKL40 as a biomarker of encephalitis and to assess its relationship to CSF viral load. CSF YKL40 and SIV RNA concentrations were analyzed over the course of infection in 19 SIV-infected pigtailed macaques and statistical analyses were performed to evaluate the relationship to encephalitis. Using these relationships, CSF alterations of 31 neuroimmune markers were studied pre-infection, during acute and asymptomatic infection, at the onset of encephalitis, and at necropsy. YKL40 CSF concentrations above 1122 ng/ml were found to be a specific and sensitive biomarker for the presence of encephalitis and were highly correlated with CSF viral load. Macaques that developed encephalitis had evidence of chronic CNS immune activation during early, asymptomatic, and end stages of infection. At the onset of encephalitis, CSF demonstrated a rise of neuroimmune markers associated with macrophage recruitment, activation and interferon response. CSF YKL40 concentration and viral load are valuable biomarkers to define the onset of encephalitis. Chronic CNS immune activation precedes the development of encephalitis while some responses suggest protection from CNS lentiviral disease.

A hallmark of cystic fibrosis (CF) lung disease is neutrophilic airway inflammation. Elevated neutrophil counts have been associated with decreased forced expiratory volume in 1 second and poor clinical measures in patients with CF. Interleukin 8 (IL-8), epithelial neutrophil activating protein 78 (ENA-78), tumor necrosis factor alpha (TNF-α), granulocyte macrophage colony-stimulating factor (GM-CSF), and granulocyte colony-stimulating factor (G-CSF) contribute to neutrophil activation and disease pathogenesis in the airways of patients with CF. Drugs that modify the production of these chemokines in the airways could potentially benefit CF patients. Thus, we determined the effects of fenofibrate on their production in cell populations obtained from the airways. Human small airway epithelial cells and CF bronchial epithelial cells were treated with IL-1β to induce inflammation. We cotreated the cells with fenofibrate at concentrations ranging from 10 to 50 μM to determine if this drug could attenuate the inflammation. IL-8, ENA-78, TNF-α, GM-CSF, and G-CSF production were measured from the cell culture supernates by ELISA. ANOVA statistical testing was conducted using SPSS 17.0. IL-1β increased the production of each of the chemokines by several fold. Fenofibrate reduced IL-1β induced production of each of these neutrophilic chemokines at the concentrations used. IL-1β increases the production of neutrophilic chemokines in airway epithelial cells. Cotreatment with fenofibrate blunts these processes. Fenofibrate should be explored as a therapeutic option to modulate the abundant neutrophilic inflammation observed in CF., (© 2015 Wiley Periodicals, Inc.)

History is replete with emergent pandemic infections that have decimated the human population. Given the shear mass of humans that now crowd the earth, there is every reason to suspect history will repeat itself. We describe three RNA viruses that have recently emerged in the human population to mediate severe neurological disease. These new diseases are results of new mutations in the infectious agents or new exposure pathways to the agents or both. To appreciate their pathogenesis, we summarize the essential virology and immune response to each agent. Infection is described in the context of known host defenses. Once the viruses evade immune defenses and enter central nervous system (CNS) cells, they rapidly co-opt host RNA processing to a cataclysmic extent. It is not clear why the brain is particularly susceptible to RNA viruses; but perhaps because of its tremendous dependence on RNA processing for physiological functioning, classical mechanisms of host defense (eg, interferon disruption of viral replication) are diminished or not available. Effectiveness of immunity, immunization and pharmacological therapies is reviewed to contextualize the scope of the public health challenge. Unfortunately, vaccines that confer protection from systemic disease do not necessarily confer protection for the brain after exposure through unconventional routes., (© 2015 International Society of Neuropathology.)