The Brazilian Zika virus strain causes birth defects in experimental models

Translocator protein (TSPO) is a biomarker of Zika virus (ZIKV) infection-associated neuroinflammation

Zika is a systemic inflammatory disease caused by infection with Zika virus (ZIKV). ZIKV infection in adults is associated with encephalitis marked by elevated expression of pro-inflammatory cytokines and chemokines, as well as increased brain infiltration of immune cells. In this study, we demonstrate that ZIKV encephalitis in a mouse infection model exhibits increased brain TSPO expression. TSPO expression on brain-resident and infiltrating immune cells in ZIKV infection correlates with disease and inflammation status in the brain. Brain TSPO expression can also be sensitively detected ex vivo and in vitro using radioactive small molecule probes that specifically bind to TSPO, such as [3H]PK11195. TSPO expression on brain-resident and infiltrating immune cells is a biomarker of ZIKV neuroinflammation, which can also be a general biomarker of acute viral neuroinflammatory disease.

Human brain organoid: trends, evolution, and remaining challenges

Advanced brain organoids provide promising platforms for deciphering the cellular and molecular processes of human neural development and diseases. Although various studies and reviews have described developments and advancements in brain organoids, few studies have comprehensively summarized and analyzed the global trends in this area of neuroscience. To identify and further facilitate the development of cerebral organoids, we utilized bibliometrics and visualization methods to analyze the global trends and evolution of brain organoids in the last 10 years. First, annual publications, countries/regions, organizations, journals, authors, co-citations, and keywords relating to brain organoids were identified. The hotspots in this field were also systematically identified. Subsequently, current applications for brain organoids in neuroscience, including human neural development, neural disorders, infectious diseases, regenerative medicine, drug discovery, and toxicity assessment studies, are comprehensively discussed. Towards that end, several considerations regarding the current challenges in brain organoid research and future strategies to advance neuroscience will be presented to further promote their application in neurological research.

The mechanisms of Zika virus-induced neuropathogenesis

Zika virus (ZIKV), a flavivirus, is one of the most serious re-emerging pathogens. Growing outbreaks in the Americas have linked ZIKV to significant clinical symptoms including Guillain-Barré syndrome in adults and congenital anomalies in newborns. ZIKV affects brain cells in a variety of ways, mostly apoptosis and cell cycle delays. Modulation of the host's immune reaction and the inflammatory process has also been shown to be involved in ZIKV-induced neurological disorders. This review summarized and discussed the latest advances in ZIKV research to shed fresh light on the multiple mechanisms incolved in ZIKV-induced neuropathogenesis.

Usutu virus, an emerging arbovirus with One Health importance

Usutu virus (USUV, Flaviviridae) is an emerging arbovirus that has led to epizootic outbreaks in birds and numerous human neuroinvasive disease cases in Europe. It is maintained in an enzootic cycle with Culex mosquitoes and passerine birds, a transmission cycle that is shared by West Nile virus (WNV) and St. Louis encephalitis virus (SLEV), two flaviviruses that are endemic in the United States. USUV and WNV co-circulate in Africa and Europe, and SLEV and WNV co-circulate in North America. These three viruses are prime examples of One Health issues, in which the interactions between humans, animals, and the environments they reside in can have important health impacts. The three facets of One Health are interwoven throughout this article as we discuss the mechanisms of flavivirus transmission and emergence. We explore the possibility of USUV emergence in the United States by analyzing the shared characteristics among USUV, WNV, and SLEV, including the role that flavivirus co-infections and sequential exposures may play in viral emergence. Finally, we provide insights on the importance of integrated surveillance programs as One Health tools that can be used to mitigate USUV emergence and spread.

Prenatal Exposure to Herbicide 2,4-Dichlorophenoxyacetic Acid (2,4D) Exacerbates Zika Virus Neurotoxicity In Vitro and In Vivo

Zika virus (ZIKV) infection during pregnancy can lead to a set of congenital malformations known as Congenital ZIKV syndrome (CZS), whose main feature is microcephaly. The geographic distribution of CZS in Brazil during the 2015-2017 outbreak was asymmetrical, with a higher prevalence in the Northeast and Central-West regions of the country, despite the ubiquitous distribution of the vector Aedes aegypti, indicating that environmental factors could influence ZIKV vertical transmission and/or severity. Here we investigate the involvement of the most used agrochemicals in Brazil with CZS. First, we exposed human neuroblastoma SK-N-AS cells to the 15 frequently used agrochemical molecules or derivative metabolites able to cross the blood-brain barrier. We found that a derived metabolite from a widely used herbicide in the Central-West region, 2,4-dichlorophenoxyacetic acid (2,4D), exacerbates ZIKV neurotoxic effects in vitro. We validate this observation by demonstrating vertical transmission leading to microcephaly in the offspring of immunocompetent C57BL/6J mice exposed to water contaminated with 0.025 mg/L of 2,4D. Newborn mice whose dams were exposed to 2,4D and infected with ZIKV presented a smaller brain area and cortical plate size compared to the control. Also, embryos from animals facing the co-insult of ZIKV and 2,4D exposition presented higher Caspase 3 positive cells in the cortex, fewer CTIP2+ neurons and proliferative cells at the ventricular zone, and a higher viral load. This phenotype is followed by placental alterations, such as vessel congestion, and apoptosis in the labyrinth and decidua. We also observed a mild spatial correlation between CZS prevalence and 2,4D use in Brazil's North and Central-West regions, with R2 = 0.4 and 0.46, respectively. Our results suggest that 2,4D exposition facilitates maternal vertical transmission of ZIKV, exacerbating CZS, possibly contributing to the high prevalence of this syndrome in Brazil's Central-West region compared to other regions.

Emerging and reemerging infectious diseases: global trends and new strategies for their prevention and control

To adequately prepare for potential hazards caused by emerging and reemerging infectious diseases, the WHO has issued a list of high-priority pathogens that are likely to cause future outbreaks and for which research and development (R&D) efforts are dedicated, known as paramount R&D blueprints. Within R&D efforts, the goal is to obtain effective prophylactic and therapeutic approaches, which depends on a comprehensive knowledge of the etiology, epidemiology, and pathogenesis of these diseases. In this process, the accessibility of animal models is a priority bottleneck because it plays a key role in bridging the gap between in-depth understanding and control efforts for infectious diseases. Here, we reviewed preclinical animal models for high priority disease in terms of their ability to simulate human infections, including both natural susceptibility models, artificially engineered models, and surrogate models. In addition, we have thoroughly reviewed the current landscape of vaccines, antibodies, and small molecule drugs, particularly hopeful candidates in the advanced stages of these infectious diseases. More importantly, focusing on global trends and novel technologies, several aspects of the prevention and control of infectious disease were discussed in detail, including but not limited to gaps in currently available animal models and medical responses, better immune correlates of protection established in animal models and humans, further understanding of disease mechanisms, and the role of artificial intelligence in guiding or supplementing the development of animal models, vaccines, and drugs. Overall, this review described pioneering approaches and sophisticated techniques involved in the study of the epidemiology, pathogenesis, prevention, and clinical theatment of WHO high-priority pathogens and proposed potential directions. Technological advances in these aspects would consolidate the line of defense, thus ensuring a timely response to WHO high priority pathogens.

Distinct Replication Kinetics, Cytopathogenicity, and Immune Gene Regulation in Human Microglia Cells Infected with Asian and African Lineages of Zika Virus

Zika virus (ZIKV), a mosquito-borne flavivirus, is a significant global health concern due to its association with neurodevelopmental disorders such as congenital Zika syndrome (CZS). This study aimed to compare the replication kinetics, viral persistence, cytopathogenic effects, and immune gene expression in human microglia cells (CHME-3) infected with an Asian lineage ZIKV (PRVABC59, referred to as ZIKV-PRV) and an African lineage ZIKV (IBH30656, referred to as ZIKV-IBH). We found that ZIKV-PRV replicated more efficiently and persisted longer while inducing lower levels of cell death and inflammatory gene activation compared with ZIKV-IBH. These findings suggest that the enhanced replication and persistence of ZIKV-PRV, along with its ability to evade innate immune responses, may underlie its increased neuropathogenic potential, especially in the context of CZS. In contrast, ZIKV-IBH, with its stronger immune gene activation and higher cytopathogenicity, may lead to more acute infections with faster viral clearance, thereby reducing the likelihood of chronic central nervous system (CNS) infection. This study provides crucial insights into the molecular and cellular mechanisms driving the differential pathogenicity of ZIKV lineages and highlights the need for further research to pinpoint the viral factors responsible for these distinct clinical outcomes.

Inhibition of sterol O-acyltransferase 1 blocks Zika virus infection in cell lines and cerebral organoids

Viruses depend on host metabolic pathways and flaviviruses are specifically linked to lipid metabolism. During dengue virus infection lipid droplets are degraded to fuel replication and Zika virus (ZIKV) infection depends on triglyceride biosynthesis. Here, we systematically investigated the neutral lipid-synthesizing enzymes diacylglycerol O-acyltransferases (DGAT) and the sterol O-acyltransferase (SOAT) 1 in orthoflavivirus infection. Downregulation of DGAT1 and SOAT1 compromises ZIKV infection in hepatoma cells but only SOAT1 and not DGAT inhibitor treatment reduces ZIKV infection. DGAT1 interacts with the ZIKV capsid protein, indicating that protein interaction might be required for ZIKV replication. Importantly, inhibition of SOAT1 severely impairs ZIKV infection in neural cell culture models and cerebral organoids. SOAT1 inhibitor treatment decreases extracellular viral RNA and E protein level and lowers the specific infectivity of virions, indicating that ZIKV morphogenesis is compromised, likely due to accumulation of free cholesterol. Our findings provide insights into the importance of cholesterol and cholesterol ester balance for efficient ZIKV replication and implicate SOAT1 as an antiviral target.

The Relationship between HERV, Interleukin, and Transcription Factor Expression in ZIKV Infected versus Uninfected Trophoblastic Cells

Zika virus (ZIKV) is an arbovirus with maternal, sexual, and TORCH-related transmission capabilities. After 2015, Brazil had the highest number of ZIVK-infected pregnant women who lost their babies or delivered them with Congenital ZIKV Syndrome (CZS). ZIKV triggers an immune defense in the placenta. This immune response counts with the participation of interleukins and transcription factors. Additionally, it has the potential involvement of human endogenous retroviruses (HERVS). Interleukins are immune response regulators that aid immune tolerance and support syncytial structure development in the placenta, where syncytin receptors facilitate vital cell-to-cell fusion events. HERVs are remnants of ancient viral infections that integrate into the genome and produce syncytin proteins crucial for placental development. Since ZIKV can infect trophoblast cells, we analyzed the relationship between ZIKV infection, HERV, interleukin, and transcription factor modulations in the placenta. To investigate the impact of ZIKV on trophoblast cells, we examined two cell types (BeWo and HTR8) infected with ZIKV-MR766 (African) and ZIKV-IEC-Paraíba (Asian-Brazilian) using Taqman and RT2 Profiler PCR Array assays. Our results indicate that early ZIKV infection (24-72 h) does not induce differential interleukins, transcription factors, and HERV expression. However, we show that the expression of a few of these host defense genes appears to be linked independently of ZIKV infection. Future studies involving additional trophoblastic cell lineages and extended infection timelines will illuminate the dynamic interplay between ZIKV, HERVs, interleukins, and transcription factors in the placenta.

Fetal MAVS and type I IFN signaling pathways control ZIKV infection in the placenta and maternal decidua

The contribution of placental immune responses to congenital Zika virus (ZIKV) syndrome remains poorly understood. Here, we leveraged a mouse model of ZIKV infection to identify mechanisms of innate immune restriction exclusively in the fetal compartment of the placenta. ZIKV principally infected mononuclear trophoblasts in the junctional zone, which was limited by mitochondrial antiviral-signaling protein (MAVS) and type I interferon (IFN) signaling mechanisms. Single nuclear RNA sequencing revealed MAVS-dependent expression of IFN-stimulated genes (ISGs) in spongiotrophoblasts but not in other placental cells that use alternate pathways to induce ISGs. ZIKV infection of Ifnar1-/- or Mavs-/- placentas was associated with greater infection of the adjacent immunocompetent decidua, and heterozygous Mavs+/- or Ifnar1+/- dams carrying immunodeficient fetuses sustained greater maternal viremia and tissue infection than dams carrying wild-type fetuses. Thus, MAVS-IFN signaling in the fetus restricts ZIKV infection in junctional zone trophoblasts, which modulates dissemination and outcome for both the fetus and the pregnant mother.

Orchestration of antiviral responses within the infected central nervous system

Many newly emerging and re-emerging viruses have neuroinvasive potential, underscoring viral encephalitis as a global research priority. Upon entry of the virus into the CNS, severe neurological life-threatening conditions may manifest that are associated with high morbidity and mortality. The currently available therapeutic arsenal against viral encephalitis is rather limited, emphasizing the need to better understand the conditions of local antiviral immunity within the infected CNS. In this review, we discuss new insights into the pathophysiology of viral encephalitis, with a focus on myeloid cells and CD8+ T cells, which critically contribute to protection against viral CNS infection. By illuminating the prerequisites of myeloid and T cell activation, discussing new discoveries regarding their transcriptional signatures, and dissecting the mechanisms of their recruitment to sites of viral replication within the CNS, we aim to further delineate the complexity of antiviral responses within the infected CNS. Moreover, we summarize the current knowledge in the field of virus infection and neurodegeneration and discuss the potential links of some neurotropic viruses with certain pathological hallmarks observed in neurodegeneration.

Zika virus vertical transmission induces neuroinflammation and synapse impairment in brain cells derived from children born with Congenital Zika Syndrome

Zika virus (ZIKV) infection was first reported in 2015 in Brazil as causing microcephaly and other developmental abnormalities in newborns, leading to the identification of Congenital Zika Syndrome (CZS). Viral infections have been considered an environmental risk factor for neurodevelopmental disorders outcome, such as Autism Spectrum Disorder (ASD). Moreover, not only the infection per se, but maternal immune system activation during pregnancy, has been linked to fetal neurodevelopmental disorders. To understand the impact of ZIKV vertical infection on brain development, we derived induced pluripotent stem cells (iPSC) from Brazilian children born with CZS, some of the patients also being diagnosed with ASD. Comparing iPSC-derived neurons from CZS with a control group, we found lower levels of pre- and postsynaptic proteins and reduced functional synapses by puncta co-localization. Furthermore, neurons and astrocytes derived from the CZS group showed decreased glutamate levels. Additionally, the CZS group exhibited elevated levels of cytokine production, one of which being IL-6, already associated with the ASD phenotype. These preliminary findings suggest that ZIKV vertical infection may cause long-lasting disruptions in brain development during fetal stages, even in the absence of the virus after birth. These disruptions could contribute to neurodevelopmental disorders manifestations such as ASD. Our study contributes with novel knowledge of the CZS outcomes and paves the way for clinical validation and the development of potential interventions to mitigate the impact of ZIKV vertical infection on neurodevelopment.

Microinstrumentation for Brain Organoids

Brain organoids are three-dimensional aggregates of self-organized differentiated stem cells that mimic the structure and function of human brain regions. Organoids bridge the gaps between conventional drug screening models such as planar mammalian cell culture, animal studies, and clinical trials. They can revolutionize the fields of developmental biology, neuroscience, toxicology, and computer engineering. Conventional microinstrumentation for conventional cellular engineering, such as planar microfluidic chips; microelectrode arrays (MEAs); and optical, magnetic, and acoustic techniques, has limitations when applied to three-dimensional (3D) organoids, primarily due to their limits with inherently two-dimensional geometry and interfacing. Hence, there is an urgent need to develop new instrumentation compatible with live cell culture techniques and with scalable 3D formats relevant to organoids. This review discusses conventional planar approaches and emerging 3D microinstrumentation necessary for advanced organoid-machine interfaces. Specifically, this article surveys recently developed microinstrumentation, including 3D printed and curved microfluidics, 3D and fast-scan optical techniques, buckling and self-folding MEAs, 3D interfaces for electrochemical measurements, and 3D spatially controllable magnetic and acoustic technologies relevant to two-way information transfer with brain organoids. This article highlights key challenges that must be addressed for robust organoid culture and reliable 3D spatiotemporal information transfer.

Zika Virus Neuropathogenesis-Research and Understanding

Zika virus (ZIKV), a mosquito-borne flavivirus, is prominently associated with microcephaly in babies born to infected mothers as well as Guillain-Barré Syndrome in adults. Each cell type infected by ZIKV-neuronal cells (radial glial cells, neuronal progenitor cells, astrocytes, microglia cells, and glioblastoma stem cells) and non-neuronal cells (primary fibroblasts, epidermal keratinocytes, dendritic cells, monocytes, macrophages, and Sertoli cells)-displays its own characteristic changes to their cell physiology and has various impacts on disease. Here, we provide an in-depth review of the ZIKV life cycle and its cellular targets, and discuss the current knowledge of how infections cause neuropathologies, as well as what approaches researchers are currently taking to further advance such knowledge. A key aspect of ZIKV neuropathogenesis is virus-induced neuronal apoptosis via numerous mechanisms including cell cycle dysregulation, mitochondrial fragmentation, ER stress, and the unfolded protein response. These, in turn, result in the activation of p53-mediated intrinsic cell death pathways. A full spectrum of infection models including stem cells and co-cultures, transwells to simulate blood-tissue barriers, brain-region-specific organoids, and animal models have been developed for ZIKV research.

Interactions Between Extracellular Vesicles and Autophagy in Neuroimmune Disorders

Neuroimmune disorders, such as multiple sclerosis, neuromyelitis optica spectrum disorder, myasthenia gravis, and Guillain-Barré syndrome, are characterized by the dysfunction of both the immune system and the nervous system. Increasing evidence suggests that extracellular vesicles and autophagy are closely associated with the pathogenesis of these disorders. In this review, we summarize the current understanding of the interactions between extracellular vesicles and autophagy in neuroimmune disorders and discuss their potential diagnostic and therapeutic applications. Here we highlight the need for further research to fully understand the mechanisms underlying these disorders, and to develop new diagnostic and therapeutic strategies.

Mapping the scientific output of organoids for animal and human modeling infectious diseases: a bibliometric assessment

The escalation of antibiotic resistance, pandemics, and nosocomial infections underscores the importance of research in both animal and human infectious diseases. Recent advancements in three-dimensional tissue cultures, or "organoids", have revolutionized the development of in vitro models for infectious diseases. Our study conducts a bibliometric analysis on the use of organoids in modeling infectious diseases, offering an in-depth overview of this field's current landscape. We examined scientific contributions from 2009 onward that focused on organoids in host‒pathogen interactions using the Web of Science Core Collection and OpenAlex database. Our analysis included temporal trends, reference aging, author, and institutional productivity, collaborative networks, citation metrics, keyword cluster dynamics, and disruptiveness of organoid models. VOSviewer, CiteSpace, and Python facilitated this analytical assessment. The findings reveal significant growth and advancements in organoid-based infectious disease research. Analysis of keywords and impactful publications identified three distinct developmental phases in this area that were significantly influenced by outbreaks of Zika and SARS-CoV-2 viruses. The research also highlights the synergistic efforts between academia and publishers in tackling global pandemic challenges. Through mostly consolidating research efforts, organoids are proving to be a promising tool in infectious disease research for both human and animal infectious disease. Their integration into the field necessitates methodological refinements for better physiological emulation and the establishment of extensive organoid biobanks. These improvements are crucial for fully harnessing the potential of organoids in understanding infectious diseases and advancing the development of targeted treatments and vaccines.

Integrated Approach for Testing and Assessment for Developmental Neurotoxicity (DNT) to Prioritize Aromatic Organophosphorus Flame Retardants

Organophosphorus flame retardants (OPFRs) are abundant and persistent in the environment but have limited toxicity information. Their similarity in structure to organophosphate pesticides presents great concern for developmental neurotoxicity (DNT). However, current in vivo testing is not suitable to provide DNT information on the amount of OPFRs that lack data. Over the past decade, an in vitro battery was developed to enhance DNT assessment, consisting of assays that evaluate cellular processes in neurodevelopment and function. In this study, behavioral data of small model organisms were also included. To assess if these assays provide sufficient mechanistic coverage to prioritize chemicals for further testing and/or identify hazards, an integrated approach to testing and assessment (IATA) was developed with additional information from the Integrated Chemical Environment (ICE) and the literature. Human biomonitoring and exposure data were identified and physiologically-based toxicokinetic models were applied to relate in vitro toxicity data to human exposure based on maximum plasma concentration. Eight OPFRs were evaluated, including aromatic OPFRs (triphenyl phosphate (TPHP), isopropylated phenyl phosphate (IPP), 2-ethylhexyl diphenyl phosphate (EHDP), tricresyl phosphate (TMPP), isodecyl diphenyl phosphate (IDDP), tert-butylphenyl diphenyl phosphate (BPDP)) and halogenated FRs ((Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP), tris(2-chloroethyl) phosphate (TCEP)). Two representative brominated flame retardants (BFRs) (2,2'4,4'-tetrabromodiphenyl ether (BDE-47) and 3,3',5,5'-tetrabromobisphenol A (TBBPA)) with known DNT potential were selected for toxicity benchmarking. Data from the DNT battery indicate that the aromatic OPFRs have activity at similar concentrations as the BFRs and should therefore be evaluated further. However, these assays provide limited information on the mechanism of the compounds. By integrating information from ICE and the literature, endocrine disruption was identified as a potential mechanism. This IATA case study indicates that human exposure to some OPFRs could lead to a plasma concentration similar to those exerting in vitro activities, indicating potential concern for human health.

Exploring the role of brain-derived extracellular vesicles in viral infections: from pathological insights to biomarker potential

Extracellular vesicles (EVs) are membrane-bound vesicles secreted by all cell types that play a central role in cell-to-cell communication. Since these vesicles serve as vehicles of cellular content (nucleic acids, proteins and lipids) with the potential to cross biological barriers, they represent a novel attractive window into an otherwise inaccessible organ, such as the brain. The composition of EVs is cell-type specific and mirrors the physiological condition of the cell-of-origin. Consequently, during viral infection, EVs undergo significant changes in their content and morphology, thereby reflecting alterations in the cellular state. Here, we briefly summarize the potential of brain-derived EVs as a lens into viral infection in the central nervous system, thereby: 1) uncovering underlying pathophysiological processes at play and 2) serving as liquid biopsies of the brain, representing a non-invasive source of biomarkers for monitoring disease activity. Although translating the potential of EVs from research to diagnosis poses complexities, characterizing brain-derived EVs in the context of viral infections holds promise to enhance diagnostic and therapeutic strategies, offering new avenues for managing infectious neurological diseases.

Zika virus infection impairs synaptogenesis, induces neuroinflammation, and could be an environmental risk factor for autism spectrum disorder outcome

Zika virus (ZIKV) infection was first associated with Central Nervous System (CNS) infections in Brazil in 2015, correlated with an increased number of newborns with microcephaly, which ended up characterizing the Congenital Zika Syndrome (CZS). Here, we investigated the impact of ZIKV infection on the functionality of iPSC-derived astrocytes. Besides, we extrapolated our findings to a Brazilian cohort of 136 CZS children and validated our results using a mouse model. Interestingly, ZIKV infection in neuroprogenitor cells compromises cell migration and causes apoptosis but does not interfere in astrocyte generation. Moreover, infected astrocytes lost their ability to uptake glutamate while expressing more glutamate transporters and secreted higher levels of IL-6. Besides, infected astrocytes secreted factors that impaired neuronal synaptogenesis. Since these biological endophenotypes were already related to Autism Spectrum Disorder (ASD), we extrapolated these results to a cohort of children, now 6-7 years old, and found seven children with ASD diagnosis (5.14 %). Additionally, mice infected by ZIKV revealed autistic-like behaviors, with a significant increase of IL-6 mRNA levels in the brain. Considering these evidence, we inferred that ZIKV infection during pregnancy might lead to synaptogenesis impairment and neuroinflammation, which could increase the risk for ASD.

Guidelines for Manufacturing and Application of Organoids: Brain

This study offers a comprehensive overview of brain organoids for researchers. It combines expert opinions with technical summaries on organoid definitions, characteristics, culture methods, and quality control. This approach aims to enhance the utilization of brain organoids in research. Brain organoids, as three-dimensional human cell models mimicking the nervous system, hold immense promise for studying the human brain. They offer advantages over traditional methods, replicating anatomical structures, physiological features, and complex neuronal networks. Additionally, brain organoids can model nervous system development and interactions between cell types and the microenvironment. By providing a foundation for utilizing the most human-relevant tissue models, this work empowers researchers to overcome limitations of two-dimensional cultures and conduct advanced disease modeling research.

Neuroinvasion of emerging and re-emerging arboviruses: A scoping review

Background

Arboviruses are RNA viruses and some have the potential to cause neuroinvasive disease and are a growing threat to global health.

Objectives

Our objective is to identify and map all aspects of arbovirus neuroinvasive disease, clarify key concepts, and identify gaps within our knowledge with appropriate future directions related to the improvement of global health.

Methods

Sources of Evidence: A scoping review of the literature was conducted using PubMed, Scopus, ScienceDirect, and Hinari. Eligibility Criteria: Original data including epidemiology, risk factors, neurological manifestations, neuro-diagnostics, management, and preventive measures related to neuroinvasive arbovirus infections was obtained. Sources of evidence not reporting on original data, non-English, and not in peer-reviewed journals were removed. Charting Methods: An initial pilot sample of 30 abstracts were reviewed by all authors and a Cohen's kappa of κ = 0.81 (near-perfect agreement) was obtained. Records were manually reviewed by two authors using the Rayyan QCRI software.

Results

A total of 171 records were included. A wide array of neurological manifestations can occur most frequently, including parkinsonism, encephalitis/encephalopathy, meningitis, flaccid myelitis, and Guillain-Barré syndrome. Magnetic resonance imaging of the brain often reveals subcortical lesions, sometimes with diffusion restriction consistent with acute ischemia. Vertical transmission of arbovirus is most often secondary to the Zika virus. Neurological manifestations of congenital Zika syndrome, include microcephaly, failure to thrive, intellectual disability, and seizures. Cerebrospinal fluid analysis often shows lymphocytic pleocytosis, elevated albumin, and protein consistent with blood-brain barrier dysfunction.

Conclusions

Arbovirus infection with neurological manifestations leads to increased morbidity and mortality. Risk factors for disease include living and traveling in an arbovirus endemic zone, age, pregnancy, and immunosuppressed status. The management of neuroinvasive arbovirus disease is largely supportive and focuses on specific neurological complications. There is a need for therapeutics and currently, management is based on disease prevention and limiting zoonosis.

New candidate genes potentially involved in Zika virus teratogenesis

Despite efforts to elucidate Zika virus (ZIKV) teratogenesis, still several issues remain unresolved, particularly on the molecular mechanisms behind the pathogenesis of Congenital Zika Syndrome (CZS). To answer this question, we used bioinformatics tools, animal experiments and human gene expression analysis to investigate genes related to brain development potentially involved in CZS. Searches in databases for genes related to brain development and CZS were performed, and a protein interaction network was created. The expression of these genes was analyzed in a CZS animal model and secondary gene expression analysis (DGE) was performed in human cells exposed to ZIKV. A total of 2610 genes were identified in the databases, of which 1013 were connected. By applying centrality statistics of the global network, 36 candidate genes were identified, which, after selection resulted in nine genes. Gene expression analysis revealed distinctive expression patterns for PRKDC, PCNA, ATM, SMC3 as well as for FGF8 and SHH in the CZS model. Furthermore, DGE analysis altered expression of ATM, PRKDC, PCNA. In conclusion, systems biology are helpful tools to identify candidate genes to be validated in vitro and in vivo. PRKDC, PCNA, ATM, SMC3, FGF8 and SHH have altered expression in ZIKV-induced brain malformations.

Biased virus transmission following sequential coinfection of Aedes aegypti with dengue and Zika viruses

BACKGROUND

Mosquito-borne arboviruses are expanding their territory and elevating their infection prevalence due to the rapid climate change, urbanization, and increased international travel and global trade. Various significant arboviruses, including the dengue virus, Zika virus, Chikungunya virus, and yellow fever virus, are all reliant on the same primary vector, Aedes aegypti. Consequently, the occurrence of arbovirus coinfection in mosquitoes is anticipated. Arbovirus coinfection in mosquitoes has two patterns: simultaneous and sequential. Numerous studies have demonstrated that simultaneous coinfection of arboviruses in mosquitoes is unlikely to exert mutual developmental influence on these viruses. However, the viruses' interplay within a mosquito after the sequential coinfection seems intricated and not well understood.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted experiments aimed at examining the phenomenon of arbovirus sequential coinfection in both mosquito cell line (C6/36) and A. aegypti, specifically focusing on dengue virus (DENV, serotype 2) and Zika virus (ZIKV). We firstly observed that DENV and ZIKV can sequentially infect mosquito C6/36 cell line, but the replication level of the subsequently infected ZIKV was significantly suppressed. Similarly, A. aegypti mosquitoes can be sequentially coinfected by these two arboviruses, regardless of the order of virus exposure. However, the replication, dissemination, and the transmission potential of the secondary virus were significantly inhibited. We preliminarily explored the underlying mechanisms, revealing that arbovirus-infected mosquitoes exhibited activated innate immunity, disrupted lipid metabolism, and enhanced RNAi pathway, leading to reduced susceptibility to the secondary arbovirus infections.

CONCLUSIONS/SIGNIFICANCE

Our findings suggest that, in contrast to simultaneous arbovirus coinfection in mosquitoes that can promote the transmission and co-circulation of these viruses, sequential coinfection appears to have limited influence on arbovirus transmission dynamics. However, it is important to note that more experimental investigations are needed to refine and expand upon this conclusion.

Revealing the clinical potential of high-resolution organoids

The symbiotic interplay of organoid technology and advanced imaging strategies yields innovative breakthroughs in research and clinical applications. Organoids, intricate three-dimensional cell cultures derived from pluripotent or adult stem/progenitor cells, have emerged as potent tools for in vitro modeling, reflecting in vivo organs and advancing our grasp of tissue physiology and disease. Concurrently, advanced imaging technologies such as confocal, light-sheet, and two-photon microscopy ignite fresh explorations, uncovering rich organoid information. Combined with advanced imaging technologies and the power of artificial intelligence, organoids provide new insights that bridge experimental models and real-world clinical scenarios. This review explores exemplary research that embodies this technological synergy and how organoids reshape personalized medicine and therapeutics.

Prevalence of urologic sequelae and bladder and bowel dysfunctions in patients with congenital Zika syndrome: A multicenter evaluation of the Zika virus bladder and bowel sequelae assistance network

INTRODUCTION

Neurogenic bladder was first confirmed as a urological sequela of Congenital Zika Syndrome (CZS) in 2018. Further clinical-epidemiological evidence also confirmed neurogenic bowel dysfunction and cryptorchidism. To strengthen the care for these children, the Congenital Zika Virus Bladder and Bowel Sequelae Network (RASZ in Brazilian) was created, including six integrated centers in Brazil. This article represents the initial outcome of the efforts by RASZ.

OBJECTIVE

To evaluate the prevalence of bladder and bowel dysfunction, cryptorchidism and other urological sequelae related to CZS in cohorts attended in six Brazilian states.

STUDY DESIGN

Observational, prospective, multicenter study including children with CZS assisted in one of six RASZ collaborative centers between June 2016 and February 2023. Data were collected from patient's first assessment using the same protocols for urological and bowel evaluation. Categorical variables were analyzed by frequency of occurrence and numerical variables by mean, median, and standard deviation. The study was approved by the Research Ethics Committees of each center, all parents/caregivers provided written informed consent.

RESULTS

The study included 414 children aged 2 months to 7 years (mean 2.77 years, SD 1.73), 227 (54.8 %) were male and 140 (33,8 %) referred urological and bowel symptoms on arrival. Prevalence of both urological and bowel sequelae was 66.7 %, 51 % of children aged 4 years and older had urinary incontinence (UI). UTI was confirmed in 23.4 % (two presented toxemia) and among males, 18.1 % had cryptorchidism. Renal ultrasonography, performed in 186 children, was abnormal in 25 (13.4 %), 7 had hydronephrosis. Among the 287 children who performed urodynamics, 283 (98.6 %) were altered: 232 had a lower bladder capacity, 144 a maximum bladder pressure of ≥40 cm H2O, and 127 did not satisfactorily empty their bladder.

DISCUSSION

A higher prevalence of NLUTD, neurogenic bowel and cryptorchidism was confirmed in children with CZS. Early diagnosis and appropriate treatment, including a multidisciplinary approach, may reduce the risk of UTIs, UI and kidney damage. A limitation of the study was the inability of children to complete the protocol, specifically urodynamic evaluation, and ultrasonography. In both exams, the percentage of abnormal cases was higher than that expected in the normal population.

CONCLUSION

A 66,7 % prevalence of combined urological sequelae and bladder-bowel dysfunction related to CZS was confirmed in patients evaluated in six Brazilian cohorts. The most frequent changes were related to NLUTD, neurogenic bowel, and cryptorchidism. Prevalence may be underestimated due to access restrictions to diagnostic tests.

Parechovirus infection in human brain organoids: host innate inflammatory response and not neuro-infectivity correlates to neurologic disease

Picornaviruses are a leading cause of central nervous system (CNS) infections. While genotypes such as parechovirus A3 (PeV-A3) and echovirus 11 (E11) can elicit severe neurological disease, the highly prevalent PeV-A1 is not associated with CNS disease. Here, we expand our current understanding of these differences in PeV-A CNS disease using human brain organoids and clinical isolates of the two PeV-A genotypes. Our data indicate that PeV-A1 and A3 specific differences in neurological disease are not due to infectivity of CNS cells as both viruses productively infect brain organoids with a similar cell tropism. Proteomic analysis shows that PeV-A infection significantly alters the host cell metabolism. The inflammatory response following PeV-A3 (and E11 infection) is significantly more potent than that upon PeV-A1 infection. Collectively, our findings align with clinical observations and suggest a role for neuroinflammation, rather than viral replication, in PeV-A3 (and E11) infection.

Brain organoid protocols and limitations

Stem cell-derived organoid technology is a powerful tool that revolutionizes the field of biomedical research and extends the scope of our understanding of human biology and diseases. Brain organoids especially open an opportunity for human brain research and modeling many human neurological diseases, which have lagged due to the inaccessibility of human brain samples and lack of similarity with other animal models. Brain organoids can be generated through various protocols and mimic whole brain or region-specific. To provide an overview of brain organoid technology, we summarize currently available protocols and list several factors to consider before choosing protocols. We also outline the limitations of current protocols and challenges that need to be solved in future investigation of brain development and pathobiology.

Use of 2D minilungs from human embryonic stem cells to study the interaction of Cryptococcus neoformans with the respiratory tract

Organoids can meet the needs between the use of cell culture and in vivo work, bringing together aspects of multicellular tissues, providing a more similar in vitro system for the study of various components, including host-interactions with pathogens and drug response. Organoids are structures that resemble organs in vivo, originating from pluripotent stem cells (PSCs) or adult stem cells (ASCs). There is great interest in deepening the understanding of the use of this technology to produce information about fungal infections and their treatments. This work aims the use 2D human lung organoid derived from human embryonic stem cells (hESCs), to investigate Cryptococcus neoformans-host interactions. C. neoformans is an opportunistic fungus acquired by inhalation that causes systemic mycosis mainly in immunocompromised individuals. Our work highlights the suitability of human minilungs for the study of C. neoformans infection (adhesion, invasion and replication), the interaction with the surfactant and induction of the host's alveolar pro-inflammatory response.

Zika purified inactivated virus (ZPIV) vaccine reduced vertical transmission in pregnant immunocompetent mice

Zika virus (ZIKV) is a significant threat to pregnant women and their fetuses as it can cause severe birth defects and congenital neurodevelopmental disorders, referred to as congenital Zika syndrome (CZS). Thus, a safe and effective ZIKV vaccine for pregnant women to prevent in utero ZIKV infection is of utmost importance. Murine models of ZIKV infection are limited by the fact that immunocompetent mice are resistant to ZIKV infection. As such, interferon-deficient mice have been used in some preclinical studies to test the efficacy of ZIKV vaccine candidates against lethal virus challenge. However, interferon-deficient mouse models have limitations in assessing the immunogenicity of vaccines, necessitating the use of immunocompetent mouse pregnancy models. Using the human stat2 knock-in (hSTAT2KI) mouse pregnancy model, we show that vaccination with a purified formalin-inactivated Zika virus (ZPIV) vaccine prior to pregnancy successfully prevented vertical transmission. In addition, maternal immunity protected offspring against postnatal challenge for up to 28 days. Furthermore, passive transfer of human IgG purified from hyper-immune sera of ZPIV vaccinees prevented maternal and fetal ZIKV infection, providing strong evidence that the neutralizing antibody response may serve as a meaningful correlate of protection.

Repurposing of Zika virus live-attenuated vaccine (ZIKV-LAV) strains as oncolytic viruses targeting human glioblastoma multiforme cells

Glioblastoma multiforme (GBM) is the most common malignant primary brain cancer affecting the adult population. Median overall survival for GBM patients is poor (15 months), primarily due to high rates of tumour recurrence and the paucity of treatment options. Oncolytic virotherapy is a promising treatment alternative for GBM patients, where engineered viruses selectively infect and eradicate cancer cells by inducing cell lysis and eliciting robust anti-tumour immune response. In this study, we evaluated the oncolytic potency of live-attenuated vaccine strains of Zika virus (ZIKV-LAV) against human GBM cells in vitro. Our findings revealed that Axl and integrin αvβ5 function as cellular receptors mediating ZIKV-LAV infection in GBM cells. ZIKV-LAV strains productively infected and lysed human GBM cells but not primary endothelia and terminally differentiated neurons. Upon infection, ZIKV-LAV mediated GBM cell death via apoptosis and pyroptosis. This is the first in-depth molecular dissection of how oncolytic ZIKV infects and induces death in tumour cells.

Zika virus co-opts microRNA networks to persist in placental niches detected by spatial transcriptomics

BACKGROUND

Zika virus congenital infection evades double-stranded RNA detection and may persist in the placenta for the duration of pregnancy without accompanying overt histopathologic inflammation. Understanding how viruses can persist and replicate in the placenta without causing overt cellular or tissue damage is fundamental to deciphering mechanisms of maternal-fetal vertical transmission.

OBJECTIVE

Placenta-specific microRNAs are believed to be a tenet of viral resistance at the maternal-fetal interface. We aimed to test the hypothesis that the Zika virus functionally disrupts placental microRNAs, enabling viral persistence and fetal pathogenesis.

STUDY DESIGN

To test this hypothesis, we used orthogonal approaches in human and murine experimental models. In primary human trophoblast cultures (n=5 donor placentae), we performed Argonaute high-throughput sequencing ultraviolet-crosslinking and immunoprecipitation to identify any significant alterations in the functional loading of microRNAs and their targets onto the RNA-induced silencing complex. Trophoblasts from same-donors were split and infected with a contemporary first-passage Zika virus strain HN16 (multiplicity of infection=1 plaque forming unit per cell) or mock infected. To functionally cross-validate microRNA-messenger RNA interactions, we compared our Argonaute high-throughput sequencing ultraviolet-crosslinking and immunoprecipitation results with an independent analysis of published bulk RNA-sequencing data from human placental disk specimens (n=3 subjects; Zika virus positive in first, second, or third trimester, CD45- cells sorted by flow cytometry) and compared it with uninfected controls (n=2 subjects). To investigate the importance of these microRNA and RNA interference networks in Zika virus pathogenesis, we used a gnotobiotic mouse model uniquely susceptible to the Zika virus. We evaluated if small-molecule enhancement of microRNA and RNA interference pathways with enoxacin influenced Zika virus pathogenesis (n=20 dams total yielding 187 fetal specimens). Lastly, placentae (n=14 total) from this mouse model were analyzed with Visium spatial transcriptomics (9743 spatial transcriptomes) to identify potential Zika virus-associated alterations in immune microenvironments.

RESULTS

We found that Zika virus infection of primary human trophoblast cells led to an unexpected disruption of placental microRNA regulation networks. When compared with uninfected controls, Zika virus-infected placentae had significantly altered SLC12A8, SDK1, and VLDLR RNA-induced silencing complex loading and transcript levels (-22; adjusted P value <.05; Wald-test with false discovery rate correction q<0.05). In silico microRNA target analyses revealed that 26 of 119 transcripts (22%) in the transforming growth factor-β signaling pathway were targeted by microRNAs that were found to be dysregulated following Zika virus infection in trophoblasts. In gnotobiotic mice, relative to mock controls, Zika virus-associated fetal pathogenesis included fetal growth restriction (P=.036) and viral persistence in placental tissue (P=.011). Moreover, spatial transcriptomics of murine placentae revealed that Zika virus-specific placental niches were defined by significant up-regulation of complement cascade components and coordinated changes in transforming growth factor-β gene expression. Finally, treatment of Zika virus-infected mice with enoxacin abolished placental Zika virus persistence, rescued the associated fetal growth restriction, and the Zika virus-associated transcriptional changes in placental immune microenvironments were no longer observed.

CONCLUSION

These results collectively suggest that (1) Zika virus infection and persistence is associated with functionally perturbed microRNA and RNA interference pathways specifically related to immune regulation in placental microenvironments and (2) enhancement of placental microRNA and RNA interference pathways in mice rescued Zika virus-associated pathogenesis, specifically persistence of viral transcripts in placental microenvironments and fetal growth restriction.

Brain organoids: A revolutionary tool for modeling neurological disorders and development of therapeutics

Brain organoids are self-organized, three-dimensional (3D) aggregates derived from pluripotent stem cells that have cell types and cellular architectures resembling those of the developing human brain. The current understanding of human brain developmental processes and neurological disorders has advanced significantly with the introduction of this in vitro model. Brain organoids serve as a translational link between two-dimensional (2D) cultures and in vivo models which imitate the neural tube formation at the early and late stages and the differentiation of neuroepithelium with whole-brain regionalization. In addition, the generation of region-specific brain organoids made it possible to investigate the pathogenic and etiological aspects of acquired and inherited brain disease along with drug discovery and drug toxicity testing. In this review article, we first summarize an overview of the existing methods and platforms used for generating brain organoids and their limitations and then discuss the recent advancement in brain organoid technology. In addition, we discuss how brain organoids have been used to model aspects of neurodevelopmental and neurodegenerative diseases, including autism spectrum disorder (ASD), Rett syndrome, Zika virus-related microcephaly, Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD).

Postnatal Zika virus infection leads to morphological and cellular alterations within the neurogenic niche

The Zika virus received significant attention in 2016, following a declaration by the World Health Organization of an epidemic in the Americas, in which infections were associated with microcephaly. Indeed, prenatal Zika virus infection is detrimental to fetal neural stem cells and can cause premature cell loss and neurodevelopmental abnormalities in newborn infants, collectively described as congenital Zika syndrome. Contrastingly, much less is known about how neonatal infection affects the development of the newborn nervous system. Here, we investigated the development of the dentate gyrus of wild-type mice following intracranial injection of the virus at birth (postnatal day 0). Through this approach, we found that Zika virus infection affected the development of neurogenic regions within the dentate gyrus and caused reactive gliosis, cell death and a decrease in cell proliferation. Such infection also altered volumetric features of the postnatal dentate gyrus. Thus, we found that Zika virus exposure to newborn mice is detrimental to the subgranular zone of the dentate gyrus. These observations offer insight into the cellular mechanisms that underlie the neurological features of congenital Zika syndrome in children.

Characterization of CD8+ T cells in immune-privileged organs of ZIKV-infected Ifnar1-/- mice

Zika virus (ZIKV) infection caused neurological complications and male infertility, leading to the accumulation of antigen-specific immune cells in immune-privileged organs (IPOs). Thus, it is important to understand the immunological responses to ZIKV in IPOs. We extensively investigated the ZIKV-specific T cell immunity in IPOs in Ifnar1-/- mice, based on an immunodominant epitope E294-302 tetramer. The distinct kinetics and functions of virus-specific CD8+ T cells infiltrated into different IPOs were characterized, with late elevation in the brain and spinal cord. Single epitope E294-302-specific T cells can account for 20-60% of the total CD8+ T cells in the brain, spinal cord, and testicle and persist for at least 90 days in the brain and spinal cord. The E294-302-specific TCRαβs within the IPOs are featured with the majority of clonotypes utilizing TRAV9N-3 paired with diverse TRBV chains, but with distinct αβ paired clonotypes in 7 and 30 days post-infection. Specific chemokine receptors, Ccr2 and Ccr5, were selectively expressed in the E294-302-specific CD8+ T cells within the brain and testicle, indicating an IPO-oriented migration of virus-specific CD8+ T cells after infection. Overall, this study adds to the understanding of virus-specific CD8+ T cell responses for controlling and clearing ZIKV infection in IPOs.IMPORTANCEThe immune-privileged organs (IPOs), such as the central nervous system and testicles, presented pathogenicity and inflammation after Zika virus (ZIKV) infection with infiltrated CD8+ T cells. Our data show that CD8+ T cells keep up with virus increases and decreases in immune-privileged organs. Furthermore, our study provides the first ex vivo comparative analyses of the composition and diversity related to TCRα/β clonotypes across anatomical sites and ZIKV infection phases. We show that the vast majority of TCRα/β clonotypes in tissues utilize TRAV9N-3 with conservation. Specific chemokine expression, including Ccr2 and Ccr5, was found to be selectively expressed in the E294-302-specific CD8+ T cells within the brain and testicle, indicating an IPO-oriented migration of the virus-specific CD8+ T cells after the infection. Our study adds insights into the anti-viral immunological characterization and chemotaxis mechanism of virus-specific CD8+ T cells after ZIKV infection in different IPOs.

The "microcephalic hydrocephalus" paradox as a paradigm of altered neural stem cell biology

Characterized by enlarged brain ventricles, hydrocephalus is a common neurological disorder classically attributed to a primary defect in cerebrospinal fluid (CSF) homeostasis. Microcephaly ("small head") and hydrocephalus are typically viewed as two mutually exclusive phenomenon, since hydrocephalus is thought of as a fluid "plumbing" disorder leading to CSF accumulation, ventricular dilatation, and resultant macrocephaly. However, some cases of hydrocephalus can be associated with microcephaly. Recent work in the genomics of congenital hydrocephalus (CH) and an improved understanding of the tropism of certain viruses such as Zika and cytomegalovirus are beginning to shed light into the paradox "microcephalic hydrocephalus" by defining prenatal neural stem cells (NSC) as the spatiotemporal "scene of the crime." In some forms of CH and viral brain infections, impaired fetal NSC proliferation leads to decreased neurogenesis, cortical hypoplasia and impaired biomechanical interactions at the CSF-brain interface that collectively engender ventriculomegaly despite an overall and often striking decrease in head circumference. The coexistence of microcephaly and hydrocephalus suggests that these two phenotypes may overlap more than previously appreciated. Continued study of both conditions may be unexpectedly fertile ground for providing new insights into human NSC biology and our understanding of neurodevelopmental disorders.

Brain organoids and organoid intelligence from ethical, legal, and social points of view

Human brain organoids, aka cerebral organoids or earlier "mini-brains", are 3D cellular models that recapitulate aspects of the developing human brain. They show tremendous promise for advancing our understanding of neurodevelopment and neurological disorders. However, the unprecedented ability to model human brain development and function in vitro also raises complex ethical, legal, and social challenges. Organoid Intelligence (OI) describes the ongoing movement to combine such organoids with Artificial Intelligence to establish basic forms of memory and learning. This article discusses key issues regarding the scientific status and prospects of brain organoids and OI, conceptualizations of consciousness and the mind-brain relationship, ethical and legal dimensions, including moral status, human-animal chimeras, informed consent, and governance matters, such as oversight and regulation. A balanced framework is needed to allow vital research while addressing public perceptions and ethical concerns. Interdisciplinary perspectives and proactive engagement among scientists, ethicists, policymakers, and the public can enable responsible translational pathways for organoid technology. A thoughtful, proactive governance framework might be needed to ensure ethically responsible progress in this promising field.

Reverse Genetics of Zika Virus Using a Bacterial Artificial Chromosome

Zika virus (ZIKV) is a mosquito-borne member of the Flaviviridae family that has become a global threat to human health. Although ZIKV has been known to circulate for decades causing mild febrile illness, the more recent ZIKV outbreaks in the Americas and the Caribbean have been associated with severe neurological disorders and congenital abnormalities. The development of ZIKV reverse genetics approaches have allowed researchers to address key questions on the biology of ZIKV by genetically engineering infectious recombinant (r)ZIKV. This has resulted in a better understanding of the biology of ZIKV infections, including viral pathogenesis, molecular mechanisms of viral replication and transcription, or the interaction of viral and host factors, among others aspects. In addition, reverse genetics systems have facilitated the identification of anti-ZIKV compounds and the development of new prophylactic approaches to combat ZIKV infections. Different reverse genetics strategies have been implemented for the recovery of rZIKV. All these reverse genetics systems have faced and overcome multiple challenges, including the viral genome size, the toxicity of viral sequences in bacteria, etc. In this chapter we describe the generation of a ZIKV full-length complementary (c)DNA infectious clone based on the use of a bacterial artificial chromosome (BAC) and the experimental procedures for the successful recovery of rZIKV. Importantly, the protocol described in this chapter provides a powerful method for the generation of infectious clones of other flaviviruses with genomes that have stability problems during bacterial propagation.

An Exploration of Organoid Technology: Present Advancements, Applications, and Obstacles

BACKGROUND

Organoids are in vitro models that exhibit a three-dimensional structure and effectively replicate the structural and physiological features of human organs. The capacity to research complex biological processes and disorders in a controlled setting is laid out by these miniature organ-like structures.

OBJECTIVES

This work examines the potential applications of organoid technology, as well as the challenges and future directions associated with its implementation. It aims to emphasize the pivotal role of organoids in disease modeling, drug discovery, developmental biology, precision medicine, and fundamental research.

METHODS

The manuscript was put together by conducting a comprehensive literature review, which involved an in-depth evaluation of globally renowned scientific research databases.

RESULTS

The field of organoids has generated significant attention due to its potential applications in tissue development and disease modelling, as well as its implications for personalised medicine, drug screening, and cell-based therapies. The utilisation of organoids has proven to be effective in the examination of various conditions, encompassing genetic disorders, cancer, neurodevelopmental disorders, and infectious diseases.

CONCLUSION

The exploration of the wider uses of organoids is still in its early phases. Research shall be conducted to integrate 3D organoid systems as alternatives for current models, potentially improving both fundamental and clinical studies in the future.

siRNA lipid nanoparticles for CXCL12 silencing modulate brain immune response during Zika infection

CXCL12 is a key chemokine implicated in neuroinflammation, particularly during Zika virus (ZIKV) infection. Specifically, CXCL12 is upregulated in circulating cells of ZIKV infected patients. Here, we developed a lipid nanoparticle (LNP) to deliver siRNA in vivo to assess the impact of CXCL12 silencing in the context of ZIKV infection. The biodistribution of the LNP was assessed in vivo after intravenous injection using fluorescently tagged siRNA. Next, we investigated the ability of the developed LNP to silence CXCL12 in vivo and assessed the resulting effects in a murine model of ZIKV infection. The LNP encapsulating siRNA significantly inhibited CXCL12 levels in the spleen and induced microglial activation in the brain during ZIKV infection. This activation was evidenced by the enhanced expression of iNOS, TNF-α, and CD206 within microglial cells. Moreover, T cell subsets exhibited reduced secretion of IFN-ɣ and IL-17 following LNP treatment. Despite no observable alteration in viral load, CXCL12 silencing led to a significant reduction in type-I interferon production compared to both ZIKV-infected and uninfected groups. Furthermore, we found grip strength deficits in the group treated with siRNA-LNP compared to the other groups. Our data suggest a correlation between the upregulated pro-inflammatory cytokines and the observed decrease in strength. Collectively, our results provide evidence that CXCL12 silencing exerts a regulatory influence on the immune response in the brain during ZIKV infection. In addition, the modulation of T-cell activation following CXCL12 silencing provides valuable insights into potential protective mechanisms against ZIKV, offering novel perspectives for combating this infection.

Neuron-Astrocyte Interactions: A Human Perspective

This chapter explores the intricate interactions between neurons and astrocytes within the nervous system with a particular emphasis on studies conducted in human tissue or with human cells. We specifically explore how neuron-astrocyte interactions relate to processes of cellular development, morphology, migration, synapse formation, and metabolism. These findings enrich our understanding of basic neurobiology and how disruptions in these processes are relevant to human diseases.The study of human neuron-astrocyte interactions is made possible because of transformative in vitro advancements that have facilitated the generation and sustained culture of human neural cells. In addition, the rise of techniques like sequencing at single-cell resolution has enabled the exploration of numerous human cell atlases and their comparisons to other animal model systems. Thus, the innovations outlined in this chapter illuminate the convergence and divergence of neuron-astrocyte interactions across species. As technologies progress, continually more sophisticated in vitro systems will increasingly reflect in vivo environments and deepen our command of neuron-glial interactions in human biology.

Role of Maternal Immune Factors in Neuroimmunology of Brain Development

Inflammation during pregnancy may occur due to various factors. This condition, in which maternal immune system activation occurs, can affect fetal brain development and be related to neurodevelopmental diseases. MIA interacts with the fetus's brain development through maternal antibodies, cytokines, chemokines, and microglial cells. Antibodies are associated with the development of the nervous system by two mechanisms: direct binding to brain inflammatory factors and binding to brain antigens. Cytokines and chemokines have an active presence in inflammatory processes. Additionally, glial cells, defenders of the nervous system, play an essential role in synaptic modulation and neurogenesis. Maternal infections during pregnancy are the most critical factors related to MIA; however, several studies show the relation between these infections and neurodevelopmental diseases. Infection with specific viruses, such as Zika, cytomegalovirus, influenza A, and SARS-CoV-2, has revealed effects on neurodevelopment and the onset of diseases such as schizophrenia and autism. We review the relationship between maternal infections during pregnancy and their impact on neurodevelopmental processes.

Development trends of human organoid-based COVID-19 research based on bibliometric analysis

Coronavirus disease 2019 (COVID-19), a global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a catastrophic threat to human health worldwide. Human stem cell-derived organoids serve as a promising platform for exploring SARS-CoV-2 infection. Several review articles have summarized the application of human organoids in COVID-19, but the research status and development trend of this field have seldom been systematically and comprehensively studied. In this review, we use bibliometric analysis method to identify the characteristics of organoid-based COVID-19 research. First, an annual trend of publications and citations, the most contributing countries or regions and organizations, co-citation analysis of references and sources and research hotspots are determined. Next, systematical summaries of organoid applications in investigating the pathology of SARS-CoV-2 infection, vaccine development and drug discovery, are provided. Lastly, the current challenges and future considerations of this field are discussed. The present study will provide an objective angle to identify the current trend and give novel insights for directing the future development of human organoid applications in SARS-CoV-2 infection.

Bibliometric analysis of cerebral organoids and diseases in the last 10 years

Cerebral organoids have emerged as a powerful tool for mirroring the brain developmental processes and replicating its unique physiology. This bibliometric analysis aims to delineate the burgeoning trends in the application of cerebral organoids in disease research and offer insights for future investigations. We screened all relevant literature from the Web of Science on cerebral organoids in disease research during the period 2013-2022 and analyzed the research trends in the field using VOSviewer, CiteSpace, and Scimago Graphica software. According to the search strategy, 592 articles were screened out. The United States of America (USA) was the most productive, followed by China and Germany. The top nine institutions in terms of the number of publications include Canada and the United States, with the University of California, San Diego (USA), having the highest number of publications. The International Journal of Molecular Sciences was the most productive journal. Knoblich, Juergen A., and Lancaster, Madeline A. published the highest number of articles. Keyword cluster analysis showed that current research trends focused more on induced pluripotent stem cells to construct organoid models of cerebral diseases and the exploration of their mechanisms and therapeutic modalities. This study provides a comprehensive summary and analysis of global research trends in the field of cerebral organoids in diseases. In the past decade, the number of high-quality papers in this field has increased significantly, and cerebral organoids provide hope for simulating nervous system diseases (such as Alzheimer's disease).

Congenital Zika Virus Infection Impairs Corpus Callosum Development

Congenital Zika syndrome (CZS) is a set of birth defects caused by Zika virus (ZIKV) infection during pregnancy. Microcephaly is its main feature, but other brain abnormalities are found in CZS patients, such as ventriculomegaly, brain calcifications, and dysgenesis of the corpus callosum. Many studies have focused on microcephaly, but it remains unknown how ZIKV infection leads to callosal malformation. To tackle this issue, we infected mouse embryos in utero with a Brazilian ZIKV isolate and found that they were born with a reduction in callosal area and density of callosal neurons. ZIKV infection also causes a density reduction in PH3+ cells, intermediate progenitor cells, and SATB2+ neurons. Moreover, axonal tracing revealed that callosal axons are reduced and misrouted. Also, ZIKV-infected cultures show a reduction in callosal axon length. GFAP labeling showed that an in utero infection compromises glial cells responsible for midline axon guidance. In sum, we showed that ZIKV infection impairs critical steps of corpus callosum formation by disrupting not only neurogenesis, but also axon guidance and growth across the midline.

Causes of microcephaly in human-theoretical considerations

As is evident from the theme of the Research Topic “Small Size, Big Problem: Understanding the Molecular Orchestra of Brain Development from Microcephaly,” the pathomechanisms leading to mirocephaly in human are at best partially understood. As molecular cell biologists and developmental neurobiologists, we present here a treatise with theoretical considerations that systematically dissect possible causes of microcephaly, which we believe is timely. Our considerations address the cell types affected in microcephaly, that is, the cortical stem and progenitor cells as well as the neurons and macroglial cell generated therefrom. We discuss issues such as progenitor cell types, cell lineages, modes of cell division, cell proliferation and cell survival. We support our theoretical considerations by discussing selected examples of factual cases of microcephaly, in order to point out that there is a much larger range of possible pathomechanisms leading to microcephaly in human than currently known.

Does the Presence or a High Titer of Yellow Fever Virus Antibodies Interfere with Pregnancy Outcomes in Women with Zika Virus Infection?

Zika virus (ZIKV) and yellow fever virus (YFV) originated in Africa and expanded to the Americas, where both are co-circulated. It is hypothesized that in areas of high circulation and vaccination coverage against YFV, children of pregnant women have a lower risk of microcephaly. We evaluated the presence and titers of antibodies and outcomes in women who had ZIKV infection during pregnancy. Pregnancy outcomes were classified as severe, moderate, and without any important outcome. An outcome was defined as severe if miscarriage, stillbirth, or microcephaly occurred, and moderate if low birth weight and/or preterm delivery occurred. If none of these events were identified, the pregnancy was defined as having no adverse effects. A sample of 172 pregnant women with an acute ZIKV infection confirmed during pregnancy were collected throughout 2016. About 89% (150 of 169) of them presented immunity against YFV, including 100% (09 of 09) of those who had severe outcomes, 84% (16 of 19) of those who had moderate outcomes, and 89% (125 of 141) of those who had non-outcomes. There was no difference between groups regarding the presence of anti-YFV antibodies (p = 0.65) and YFV titers (p = 0.6). We were unable to demonstrate a protective association between the presence or titers of YFV antibodies and protection against serious adverse outcomes from exposure to ZIKV in utero.

Prenatal Zika virus exposure is associated with lateral geniculate nucleus abnormalities in juvenile rhesus macaques

Zika virus' neural tropism causes significant neural pathology, particularly in developing fetuses. One of the consistent findings from humans and animal models is that prenatal exposure to Zika virus (ZIKV) causes pathology in the eyes and visual pathways of the brain, although the extent to which this pathology persists over development is not clear. In the present report, we build upon our previous work which demonstrated that full-term rhesus monkey ( Macaca mulatta ) fetuses who were exposed to ZIKV early in gestation had significant pathological abnormalities to the organization of the lateral geniculate nucleus (LGN), a major hub of the visual network. The objective of the present work was to replicate those LGN findings and determine whether such pathology persisted across childhood development. We carried out histological analyses of the LGNs of two juvenile rhesus monkeys who were prenatally exposed to ZIKV and two age-matched controls. Pregnant rhesus monkeys were infected with ZIKV via the intravenous and intra-amniotic routes and tracked across development. Following sacrifice and perfusion, brains were subjected to quantitative neuroanatomical analyses with a focus on the size and structure of the LGN and its composite layers. Early fetal ZIKV exposure resulted in developmental abnormalities within the brains' visual pathway: specifically disorganization, blending of layers, laminar discontinuities, and regions of low cell density within the LGN. These abnormalities were not observed in the control animals. Our findings demonstrate that the ZIKV's damage to the LGN that occurs during fetal development persists into childhood.

Interplay Between Zika Virus-Induced Autophagy and Neural Stem Cell Fate Determination

The Zika virus (ZIKV) outbreaks and its co-relation with microcephaly have become a global health concern. It is primarily transmitted by a mosquito, but can also be transmitted from an infected mother to her fetus causing impairment in brain development, leading to microcephaly. However, the underlying molecular mechanism of ZIKV-induced microcephaly is poorly understood. In this study, we explored the role of ZIKV non-structural protein NS4A and NS4B in ZIKV pathogenesis in a well-characterized primary culture of human fetal neural stem cells (fNSCs). We observed that the co-transfection of NS4A and NS4B altered the neural stem cell fate by arresting proliferation and inducing premature neurogenesis. NS4A + NS4B transfection in fNSCs increased autophagy and dysregulated notch signaling. Further, it also altered the regulation of downstream genes controlling cell proliferation. Additionally, we reported that 3 methyl-adenine (3-MA), a potent autophagy inhibitor, attenuated the deleterious effects of NS4A and NS4B as evidenced by the rescue in Notch1 expression, enhanced proliferation, and reduced premature neurogenesis. Our attempts to understand the mechanism of autophagy induction indicate the involvement of mitochondrial fission and ROS. Collectively, our findings highlight the novel role of NS4A and NS4B in mediating NSC fate alteration through autophagy-mediated notch degradation. The study also helps to advance our understanding of ZIKV-induced neuropathogenesis and suggests autophagy as a potential target for anti-ZIKV therapeutic intervention.

Prenatal Zika virus infection has sex-specific effects on infant physical development and mother-infant social interactions

There is enormous variation in the extent to which fetal Zika virus (fZIKV) infection affects the developing brain. Despite the neural consequences of fZIKV infection observed in people and animal models, many open questions about the relationship between infection dynamics and fetal and infant development remain. To further understand how ZIKV affects the developing nervous system and the behavioral consequences of prenatal infection, we adopted a nonhuman primate model of fZIKV infection in which we inoculated pregnant rhesus macaques and their fetuses with ZIKV in the early second trimester of fetal development. We then tracked their health across gestation and characterized infant development across the first month of life. ZIKV-infected pregnant mothers had long periods of viremia and mild changes to their hematological profiles. ZIKV RNA concentrations, an indicator of infection magnitude, were higher in mothers whose fetuses were male, and the magnitude of ZIKV RNA in the mothers' plasma or amniotic fluid predicted infant outcomes. The magnitude of ZIKV RNA was negatively associated with infant growth across the first month of life, affecting males' growth more than females' growth, although for most metrics, both males and females evidenced slower growth rates as compared with control animals whose mothers were not ZIKV inoculated. Compared with control infants, fZIKV infants also spent more time with their mothers during the first month of life, a social behavior difference that may have long-lasting consequences on psychosocial development during childhood.

DNA damage and repair: underlying mechanisms leading to microcephaly

DNA-damaging agents and endogenous DNA damage constantly harm genome integrity. Under genotoxic stress conditions, the DNA damage response (DDR) machinery is crucial in repairing lesions and preventing mutations in the basic structure of the DNA. Different repair pathways are implicated in the resolution of such lesions. For instance, the non-homologous DNA end joining and homologous recombination pathways are central cellular mechanisms by which eukaryotic cells maintain genome integrity. However, defects in these pathways are often associated with neurological disorders, indicating the pivotal role of DDR in normal brain development. Moreover, the brain is the most sensitive organ affected by DNA-damaging agents compared to other tissues during the prenatal period. The accumulation of lesions is believed to induce cell death, reduce proliferation and premature differentiation of neural stem and progenitor cells, and reduce brain size (microcephaly). Microcephaly is mainly caused by genetic mutations, especially genes encoding proteins involved in centrosomes and DNA repair pathways. However, it can also be induced by exposure to ionizing radiation and intrauterine infections such as the Zika virus. This review explains mammalian cortical development and the major DNA repair pathways that may lead to microcephaly when impaired. Next, we discuss the mechanisms and possible exposures leading to DNA damage and p53 hyperactivation culminating in microcephaly.