Visualizing in deceased COVID-19 patients how SARS-CoV-2 attacks the respiratory and olfactory mucosae but spares the olfactory bulb

Exploring the pathogenic and transmission characteristics of JN.1 in golden hamsters based on different attack methods

Since its emergence at the end of 2023, the JN.1 variant of COVID-19 has become the dominant strain globally. Currently, its characteristics in related animal models remain largely unknown. The results indicate that JN.1 can cause weight loss, viral load, viral titer, and histopathological changes in golden hamsters via intranasal and intragastric inoculation methods, with intranasal inoculation leading to faster viral replication. Interestingly, both viral load and viral titer of JN.1 are significantly lower than those of its parental strains BA.2 and XBB EG.5.1. A comparison of hematological data from the two inoculation methods was also consistent with previous findings. This highlights the importance of the infection route in studying the virus's progression and characteristics. In direct transmission studies of JN.1, the minimum time for virus transmission was 24 h, while XBB EG.5.1 could transmit the virus in as little as 6 h. Finally, the in vivo adaptability of JN.1 was investigated, with XBB EG.5.1 showing a more apparent adaptability advantage. Therefore, compared with EG.5.1, the pathogenicity and transmissibility of JN.1 are significantly weakened.

Deficiency of Aging-Related Gene Chitinase-Like 4 Impairs Olfactory Epithelium Homeostasis

Mammalian olfactory epithelium (OE) undergoes consistent self-renewal throughout life. In OE homeostasis, globose basal cells (GBCs) contribute to the generation of olfactory sensory neurons (OSNs) to replace old ones. Chitinase-like 4 (Chil4), a chitinase-like protein expressed in supporting cells, plays a critical role in OE regeneration, while its role in tissue homeostasis is still elusive. Here, we found that Chil4 is upregulated in the aged OE. Deletion of Chil4 leads to a reduction in the number of GBCs and immature OSNs (iOSNs). Chil4-/- GBCs show attenuation in cell cycle progression and an aberrant expression pattern of cell-cycle-related genes such as Cdk1. Chil4 deletion causes loss of a specific subcluster of GAP43+ iOSNs expressing Cebpb, Nqo1 and low level of mature OSN (mOSN) marker Stoml3 (iOSN_CeStLNq), potentially suggesting a transitional state between immature and mature neurons. Chil4 knockout induces inflammatory activation in Iba1+ microglia (MG)-like cells in the OE. Chil4 downregulation in aged organoids reduced the number of mature sensory neurons, suggesting a necessary role of Chil4 in maintaining neuronal generation in the aged OE. Collectively, these observations reveal a previously unidentified function of Chil4, establishing the cellular mechanism underlying OE homeostasis.

Olfactory receptors and human diseases

Olfaction plays a crucial role in distinguishing odors, enabling organisms to seek benefits and evade hazards. Olfactory receptors (ORs), characterized by highly variable binding pockets, facilitate the detection of diverse odorants from both external and internal environments. Nasal ORs, expressed in olfactory sensory neurons (OSNs), are critical for olfactory cognition and associated neuronal plasticity. In contrast, extra-nasal ORs, expressed in extra-olfactory tissues, detect specific chemicals and modulate cellular processes such as proliferation, migration, inflammation, and apoptosis. Aberrant OR expression or dysfunction has been implicated in numerous human diseases, including anosmia, dementia, dermatopathies, obesity, infertility, cancers, respiratory disorders, atherosclerosis and viral infections. Olfactory training, such as aromatherapy, demonstrates significant therapeutic potential for anosmia, dementia and psychological distress. Natural or synthetic odorants have been applied for promoting hair regeneration and cutaneous wound healing. Conversely, overexpression of specific ORs in cancer cells may drive tumor progression. Additionally, ORs may mediate virus-host interactions during infection, owing to their structural variability. Collectively, OR-targeted agonists and antagonists (odorants) represent promising candidates for treating OR-associated pathologies.

Factors associated with the presence and intensity of ongoing symptoms in Long COVID

OBJECTIVE

Identification of modifiable factors associated with symptom intensity among people seeking care for Post-Acute Sequelae of SARS-CoV-2 infection (PASC) could help guide the development of comprehensive, whole-person care pathways to alleviate symptoms irrespective of potential underlying pathophysiologies. We aimed to better define the key contributors to PASC, and sought the factors associated with PASC symptom presence and intensity.

METHODS

In this cross-sectional study, 249 patients presenting for PASC care at a dedicated Post-COVID-19 clinic completed a standardized screening assessment prior to initial visit and evaluation by a general internist or nurse practitioner. We measured 46 symptoms based on the WHO's Global COVID-19 Clinical Platform Case Report Form for Post COVID Condition and performed a factor analysis and item response theory based 2-parameter logistic model to develop a population-based t-score to measure PASC symptom presence and intensity (PASC-SPI). A multivariable linear regression analysis was used to assess factors associated with PASC-SPI, accounting for demographics, comorbidities, COVID-19 infection duration and severity, and mental health.

RESULTS

Greater PASC-SPI was associated with greater symptoms of anxiety, a longer duration of COVID-19 infection, and hypercholesterolemia. Lower PASC-SPI was associated with older age, self-reported 1-3 units of alcohol per week, and self-reported clinician confirmation of COVID-19 diagnosis. Symptoms of anxiety accounted for a considerably higher proportion of variation in PASC-SPI than other variables.

CONCLUSION

Symptoms of anxiety were the strongest correlate of PASC-SPI, highlighting it as both a potential neuroinflammatory marker of PASC and a modifiable component of the illness. This emphasizes the need for comprehensive, whole person treatment strategies that integrate evidence-based interventions to address the multifaceted nature of PASC.

Neuroinvasive and neurovirulent potential of SARS-CoV-2 in the acute and post-acute phase of intranasally inoculated ferrets

Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) can cause systemic disease, including neurological complications, even after mild respiratory disease. Previous studies have shown that SARS-CoV-2 infection can induce neurovirulence through microglial activation in the brains of patients and experimentally inoculated animals, which are models representative for moderate to severe respiratory disease. Here, we aimed to investigate the neuroinvasive and neurovirulent potential of SARS-CoV-2 in intranasally inoculated ferrets, a model for subclinical to mild respiratory disease. The presence of viral RNA, histological lesions, virus-infected cells, and the number and surface area of microglia and astrocytes were investigated. Viral RNA was detected in various respiratory tissue samples by qPCR at 7 days post inoculation (dpi). Virus antigen was detected in the nasal turbinates of ferrets sacrificed at 7 dpi and was associated with inflammation. Viral RNA was detected in the brains of ferrets sacrificed 7 dpi, but in situ hybridization nor immunohistochemistry did confirm evidence for viral RNA or antigen in the brain. Histopathological analysis of the brains showed no evidence for an influx of inflammatory cells. Despite this, we observed an increased number of Alzheimer type II astrocytes in the hindbrains of SARS-CoV-2 inoculated ferrets. Additionally, we detected increased microglial activation in the olfactory bulb and hippocampus, and a decrease in the astrocytic activation status in the white matter and hippocampus of SARS-CoV-2 inoculated ferrets. In conclusion, although SARS-CoV-2 has limited neuroinvasive potential in this model for subclinical to mild respiratory disease, there is evidence for neurovirulent potential. This study highlights the value of this ferret model to study the neuropathogenecity of SARS-CoV-2 and reveals that a mild SARS-CoV-2 infection can affect both microglia and astrocytes in different parts of the brain.

Processing of genomic RNAs by Dicer in bat cells limits SARS-CoV-2 replication

Bats are reservoirs for numerous viruses that cause serious diseases in other animals and humans. Several mechanisms are proposed to contribute to the tolerance of bats to these pathogens. This study investigates the response of bat cells to double-stranded RNA generated by SARS-CoV-2 replication. Here, we found the involvement of Dicer in the processing of viral genomic RNAs during SARS-CoV-2 infection. Examining RNA sequencing of infected cells, small-interfering RNA (siRNA)-like fragments were found derived from viral RNAs. Depletion of Dicer showed a reduction in these RNAs and an increase in viral loads suggesting unlike other mammals, bats may use Dicer to limit viral replication. This prompted the exploration of key dsRNA sensors in bat cells. Our analysis showed significant upregulation of OAS1 and MX1 in response to dsRNA, while PKR levels remained low, suggesting alternative dsRNA-response mechanisms are present that eschew the common PKR-based system. These results further show how bats employ distinct strategies for antiviral defense that may contribute to tolerating viral infections. They suggest the involvement of Dicer in antiviral mechanisms in bats, a function not observed in other mammals. This highlights a mechanism for bat originating viruses to evolve features that in other animals could cause extreme antiviral responses such as is seen with SARS-CoV-2.

Single-cell transcriptomics reveals a compartmentalized antiviral interferon response in the nasal epithelium of mice

Type III interferons (IFNs) primarily act on epithelial cells and protect against virus infection of the mucosa, whereas type I IFNs act more systemically. To date, it has been unknown which epithelial subtypes in the upper airways, the primary site for initial infection for most respiratory viruses, primarily rely on type III IFN or type I IFNs for antiviral protection. To address this question, we performed a single-cell transcriptomics analysis of the epithelial IFN-mediated response focusing on the upper airways of mice. This work identified nine distinct cell types derived from the olfactory epithelium and thirteen distinct cell types from the respiratory epithelium. Interestingly, type I IFNs induced a stronger antiviral transcriptional response than type III IFN in respiratory epithelial cells, whereas in olfactory epithelial cells, including sustentacular (SUS) and Bowman's gland cells (BGC), type III IFN was more dominant compared to type I IFN. SUS and BGC, which provide structural support and maintain the integrity of olfactory sensory neurons, were highly susceptible to infection with a mouse-adapted variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 MA20) but were protected against infection if the animals were prophylactically treated with type III IFN. These findings demonstrate a high degree of cell type heterogeneity in terms of interferon-mediated antiviral responses and reveal a potent role for type III IFNs in protecting the olfactory epithelium.IMPORTANCESARS-CoV-2 infects SUS and BGC in the olfactory epithelium, causing an impairment of structural support and integrity of olfactory sensory neurons that can result in severe olfactory dysfunctions. We observed an unexpected compartmentalization of the IFN-mediated transcriptional response within the airway epithelium, and we found that olfactory epithelial cells preferentially respond to type III IFN, which resulted in robust antiviral protection of SUS and BGC. Given the proximity of the olfactory epithelium to the central nervous system, we hypothesize that evolution favored a type III IFN-biased antiviral immune response in this tissue to limit inflammatory responses in the brain. Cell type-specific antiviral responses in the upper airways, triggered by the different types of IFNs, should be investigated in more detail and carefully taken into consideration during the development of IFN-based antivirals for clinical use.

Cells that survive acute SARS-CoV-2 infection contribute to inflammation and lung regeneration in mice

Post-acute sequelae of COVID-19 involves several organs, but its basis remains poorly understood. Some infected cells in mice survive the acute infection and persist for extended periods in the respiratory tract but not in other tissues. Here, we describe two experimental models of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection to assess the effect of viral virulence on previously infected cells. Both approaches use lineage tracking of previously infected cells. In mice infected with a highly pathogenic mouse-adapted SARS-CoV-2, alveolar type 2 cells (AT2) but not alveolar type 1 (AT1) cells survived the acute infection. These cells became activated, differentiated into an AT2-to-AT1 transitional cell state (KRT8+ pre-alveolar type 1 transitional cell state). Additionally, nearby uninfected AT2 cells upregulated the transitional marker KRT8, thereby contributing to lung regeneration. In mice sensitized to infection by transduction with Ad5-hACE2, the infection is nonlethal, and AT1 cells survived the infection. Consequently, recovery in these mice was more rapid. Taken together, these results provide an explanation for how SARS-CoV-2 virulence contributes to poor outcomes and affects clinical recovery and lung regeneration. We also identified a new mechanism by which SARS-CoV-2 impacts lung recovery, even at times when infectious virus cannot be detected.

IMPORTANCE

A major consequence of the COVID-19 pandemic is that many survivors have long-term sequelae, which are not well understood. These involve many organs, with the respiratory tract being a common site of long-term effects. Many of these sequelae can be found in mice infected with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In this study, we have focused on the lungs, with particular interest in the fate and role of cells that were infected with SARS-CoV-2 and survived the acute infection. We found that some infected cells survive acute SARS-CoV-2 infection and that these surviving cells both contribute to the immune response in the lungs and are involved in lung recovery. These findings illustrate previously unexplored aspects of recovery from SARS-CoV-2 induced pneumonia and may be relevant for understanding aspects of post-acute sequelae of COVID-19.

Olfactory Development and Dysfunction: Involvement of Microglia

Olfactory deficits are increasingly recognized in a variety of neurological, neurodevelopmental, psychiatric, and viral diseases. While the pathology underlying olfactory loss is likely to differ across diseases, one shared feature may be an immune response mediated by microglia. Microglia orchestrate the brain's response to environmental insults and maintain neurodevelopmental homeostasis. Here, we explore the potential involvement of microglia in olfactory development and loss in disease. The effects of microglia-mediated immune response during development may be of special relevance to the olfactory system, which is unique in both its vulnerability to environmental insults as well as its extended period of neurogenesis and neuronal migration.

Emerging and re-emerging viral infections of the central nervous system in Australasia and beyond

Viral infections of the central nervous system (CNS) have been emerging and re-emerging worldwide, and the Australasia region has not been spared. Enterovirus A71 and enterovirus D68, both human enteroviruses, are likely to replace the soon-to-be eradicated poliovirus to cause global outbreaks associated with neurological disease. Although prevalent elsewhere, the newly emergent orthoflavivirus, Japanese encephalitis virus (genotype IV), caused human infections in Australia in 2021, and almost certainly will continue to do so because of spillovers from the natural animal host-vector life cycle endemic in the country. Another orthoflavivirus, Murray Valley encephalitis virus, has re-emerged in Australia. The Hendra henipavirus together with Nipah henipavirus ​are listed as high-risk pathogens by the World Health Organization because both can cause lethal encephalitis. The former remains a health threat in Australasia because bats may still be able to spread the infection to unvaccinated Australian horses and other animals acting as intermediate hosts, and thence to humans. The global COVID-19 pandemic, caused by the emerging severe acute respiratory syndrome coronavirus-2, a virus transmitted from animals to humans that was first described and first arose in China, is associated with acute and long-lasting CNS pathology. Fortunately, the pathology and pathogenesis of these important neurotropic viruses are now better understood, leading to better management protocols and prevention strategies. Pathologists are in a unique position to contribute to the diagnosis and advancement in our knowledge of infectious diseases. This review summarises some of the current knowledge about a few important emerging and re-emerging CNS infections in Australasia and beyond.

The Effectiveness of Functional Septorhinoplasty in Improving COVID-19-related Olfactory Dysfunction

Long-Term COVID-19-related olfactory dysfunction (C19OD) remains a significant challenge with no established treatment providing meaningful improvement. This study aimed to assess the efficacy of functional septorhinoplasty (fSRP) in improving olfactory dysfunction in patients with persistent C19OD compared to a control group undergoing olfactory training (OT). In this prospective study patients with persistent C19OD undergoing fSRP were enrolled while those declining surgery continued with OT as the control group. Patients were followed for six months with olfactory function assessed using Sniffin' Sticks (S'S) and nasal airflow evaluated through peak nasal inspiratory flow (PNIF) and acoustic rhinometry (AR). Among the participants 12 underwent fSRP while 13 were in the control group. Significant improvements (p < 0.05) in all S'S scores were observed in the fSRP group but not in the control group. TDI scores improved above the minimal clinically important difference only in the fSRP group. Strong correlations were found between olfactory scores and nasal measurements. Comparison of olfactory threshold gains between groups revealed a statistically significant benefit in the fSRP group. These findings suggest that fSRP can significantly improve persistent C19OD providing a notable olfactory threshold gain compared to OT.

Neuroinvasion via Peripheral Nerves in Epidemic Viral Encephalitis Caused by Enterovirus, Orthoflavivirus and SARS-Coronavirus

Pathogens invade the central nervous system (CNS) and cause infections either through the haematogenous route or via peripheral nerves. Neuroinvasion via peripheral nerves, involving spinal or cranial somatic nerves, is well-established for certain viral encephalitides such as rabies, herpes simplex encephalitis, and poliomyelitis. Advances in understanding emerging and re-emerging viruses that cause epidemic CNS infections have highlighted the growing importance of peripheral nerve pathways in viral neuroinvasion. This review focuses on epidemic viral encephalitides caused by three groups of RNA viruses, viz., enteroviruses (enterovirus A71 and enterovirus D68), orthoflaviviruses (West Nile virus and Japanese encephalitis virus), and severe acute respiratory syndrome coronaviruses (mainly severe acute respiratory coronavirus-2). We examine evidence supporting the hypothesis that peripheral nerve viral transmission may play an increasingly significant if not more critical role than the haematogenous route in neuroinvasion.

Association of olfactory training with olfactory bulb morphology in adults with post-viral long-lasting olfactory dysfunction: A COVID-19 related prospective study

OBJECTIVE

In this prospective case-controlled study, we aimed to examine changes in olfactory bulb (OB) morphology due to COVID-19 infection and to examine the effects of olfactory training (OT).

METHODS

This study included 29 patients with anosmia or hyposmia due to COVID-19 infection (Group 1), 24 normosmic patients after COVID-19 infection (Group 2), and 25 normosmic subjects without COVID-19 infection (Group 3). OB volumes, thickness, length, sulcus depth, and signal intensity were evaluated using magnetic resonance imaging (MRI). Psychophysical tests (odor discrimination, thresholds, and odor identification) and a survey of olfactory symptoms were performed. After 12 weeks of OT, the MRI data and odor scores of Group 1 were compared with those of the other groups.

RESULTS

OB volumes were significantly smaller in Group 1 (54.01±2.92 mm3) compared with the other groups (group 2:56.7±3.2 mm3 and group 3:59.45±3.09 mm3). The OB thicknesses and lengths differed significantly between Group 1 and Groups 2 and 3. Group 1 had abnormalities in the OB signal intensity in the form of diffusely increased signal intensity compared with the others groups. Following OT, OB volume (right, p= 0.002; left, p=0.021) and Threshold Discrimination Identification score (p< 0.001) significantly increased in Group 1 patients.

CONCLUSION

These findings suggest that post-COVID olfactory loss is associated with smaller OB volumes and increased OB signal intensity. Additionally, this study provides evidence supporting the effectiveness of OT in improving olfactory function and OB volume in patients with long-lasting post-COVID-19 symptoms.

Neurological syndromes associated with COVID-19: a multicenter study in Brazil

BACKGROUND

Neurological manifestations associated with COVID-19 remain partially described, mainly in low- and middle-income countries where diagnostic tools are limited. To address this, we assembled medical centers in Brazil with the goal of describing neurological syndromes associated with COVID-19 during the first wave of the pandemic.

METHODS

From June 1st, 2020 to June 1st, 2021, non-consecutive adult patients with new onset of six neurological syndromes up to 60 days after confirmed COVID-19 were included. Data were compiled from four tertiary centers and compared with general local COVID-19 data, as well as with a previous cohort focused on vascular syndrome.

RESULTS

197 patients were included, presenting with vascular syndromes (81), encephalopathy (68), encephalitis (19), Guillain-Barré syndrome (13), other neuropathies (12), and myelitis (4). The incidence curve of neurocovid mirrored that of COVID-19. Neurological syndromes were present regardless of COVID-19 severity. The median time from COVID-19 to onset of neurological symptoms was 14 days, suggesting a post-infectious immune-mediated mechanism. Patients were 10 times more likely to die (χ2 (1) = 356.55, p < 0.01, OR = 10.89) and 38 times more likely to be hospitalized than other COVID-19 patients (χ2 (1) = 1167.9, p < 0.01, OR = 38.22). Those developing vascular syndromes patients were 3 times more likely to require ICU (χ2 (1) = 37.12, p < 0.01, OR = 3.78) and 4 times more likely to die (χ2 (1) = 58.808, p < 0.01, OR = 4.73) than patients with vascular syndromes due to different etiologies.

CONCLUSIONS

Our study corroborates the association of neurological syndromes with COVID-19. The incidence correlated with local waves of COVID-19, and patients with neurocovid exhibited a higher susceptibility to adverse outcomes compared to other COVID-19 patients. Among all neurological syndromes, vascular syndromes were the most common, and their severity surpassed that of vascular syndromes not attributed to COVID-19.

Parosmia: Pathophysiology and Management

PURPOSE OF REVIEW

Parosmia is a qualitative olfactory disorder in which there is a mismatch between the memory of an odor and the actual experience triggered by an odor. There has been a surge in parosmia-related publications since the COVID-19 pandemic. This review summarizes the latest clinical findings, theories on pathophysiology and potential treatment options.

RECENT ADVANCES

Potential models of parosmia include peripheral or central hypotheses, which refer to aberrancies in olfactory neuron regeneration or information processing in central olfactory centers respectively. This leads to an incomplete or disorganized pattern of olfactory information relay. Studies using gas chromatography and functional magnetic resonance imaging have identified molecular triggers and intracranial functional connectivity patterns in parosmia respectively. Parosmia tends to occur in a delayed fashion after virus-induced anosmia. It may run a protracted course, but typically improves over time. Currently there are no generally approved, objective ways to ascertain the presence and measure the extent of parosmia. Evidence-based treatment for parosmia remains elusive. In some people, this can lead to health and quality of life issues.

Animal Models of Non-Respiratory, Post-Acute Sequelae of COVID-19

Post-acute sequelae of COVID-19 (PASC) are a diverse set of symptoms and syndromes driven by dysfunction of multiple organ systems that can persist for years and negatively impact the quality of life for millions of individuals. We currently lack specific therapeutics for patients with PASC, due in part to an incomplete understanding of its pathogenesis, especially for non-pulmonary sequelae. Here, we discuss three animal models that have been utilized to investigate PASC: non-human primates (NHPs), hamsters, and mice. We focus on neurological, gastrointestinal, and cardiovascular PASC and highlight advances in mechanistic insight that have been made using these animal models, as well as discussing the sequelae that warrant continued and intensive research.

Challenges and Opportunities in the Clinical Translation of High-Resolution Spatial Transcriptomics

Pathology has always been fueled by technological advances. Histology powered the study of tissue architecture at single-cell resolution and remains a cornerstone of clinical pathology today. In the last decade, next-generation sequencing has become informative for the targeted treatment of many diseases, demonstrating the importance of genome-scale molecular information for personalized medicine. Today, revolutionary developments in spatial transcriptomics technologies digitalize gene expression at subcellular resolution in intact tissue sections, enabling the computational analysis of cell types, cellular phenotypes, and cell-cell communication in routinely collected and archival clinical samples. Here we review how such molecular microscopes work, highlight their potential to identify disease mechanisms and guide personalized therapies, and provide guidance for clinical study design. Finally, we discuss remaining challenges to the swift translation of high-resolution spatial transcriptomics technologies and how integration of multimodal readouts and deep learning approaches is bringing us closer to a holistic understanding of tissue biology and pathology.

The Feasibility of Investigating Acupuncture in Patients With COVID-19 Related Olfactory Dysfunction

Background

Olfactory dysfunction (OD) is a common symptom in patients with coronavirus disease 2019 (COVID-19) with limited treatment options.

Objective

This pilot study aimed to investigate an acupuncture protocol in patients with COVID-19 related OD.

Methods

Thirty patients were randomized into 2 groups. The standard group was treated with budesonide nasal irrigation and olfactory training. The acupuncture group received ten sessions of acupuncture therapy in addition to the standard group treatment. Olfaction was assessed using the University of Pennsylvania Smell Identification Test, 10-point visual analog scale, and Sino-Nasal Outcome Test at baseline and after 3 months of treatment. Differences between study arms were compared using Fisher's exact and Wilcoxon rank sum tests.

Results

Eighteen of the 30 (60%) enrolled patients completed the study, including 11 (73%) in the standard and 7 (47%) in the acupuncture group. Reasons for participant drop-out included cost of travel and time constraints. There were no acupuncture complications.

Conclusions

Acupuncture as an adjunct therapy for COVID-19 related OD is well tolerated. Subsequent studies with larger sample sizes are needed to assess the effect of acupuncture on OD.

Reemerging Infectious Diseases and Neuroimmunologic Complications

During the past decade (and beyond), neurologists have become aware of the emergence, persistence, and consequences of some familiar and new infections affecting the nervous system. Even among the familiar CNS infections, such as herpes virus, polyoma virus/JC, influenza, arbovirus, and hepatitis, challenges remain in developing effective antiviral treatments and treatments of postinfection sequelae. With the changing environment and increased global travel, arthropod vectors that mediate zoonotic disease transmission have spread unfamiliar viruses such as West Nile virus, dengue, chikungunya, equine encephalitis, and Zika, among others. Although the global health impact of these diseases has not risen to that of COVID-19 and HIV, it is likely to dramatically increase with continued spread of transmission vectors and the emergence of new zoonotic animal-to-human diseases mediated by those transmission vectors. Furthermore, specific virus-targeting treatments or effective vaccines for arboviral infections are not yet available, and this represents a major challenge in limiting the morbidity of these infections. By contrast, HIV-1, a disease that originated by direct transmission from nonhuman primates to humans (as early as the 1930s), after many years of intense study, is now targeted by highly specific and effective antiviral drugs that can limit the spread of infection and extend human life and health in all populations. Even with these dramatic therapeutic effects of suppressing HIV replication, neurologic dysfunction (primarily cognitive impairment) affects significant numbers of persons living with HIV. This emphasizes not only the importance of treating the underlying infection but also developing treatments for legacy effects of the initial infection even after antiviral therapy. Notably, the rapid emergence of SARS-CoV-2 infection was met with rapid implementation of highly effective and specific antiviral therapies. This resulted in early and dramatic lowering of the morbidity and mortality of SARS-CoV-2 infection. Nonetheless, the postinfectious complications of SARS-CoV-2 infection (long COVID) are now among the more costly consequences of emerging zoonotic infections worldwide. Developing new antiviral therapies that can penetrate the CNS, vaccines, and therapies that target host immune responses and metabolic dysfunction will be necessary for management of infectious and postinfectious complications of established and emerging infections.

COVID-19 vaccines: Immune correlates and clinical outcomes

Severe disease due to COVID-19 has declined dramatically as a result of widespread vaccination and natural immunity in the population. With the emergence of SARS-CoV-2 variants that largely escape vaccine-elicited neutralizing antibody responses, the efficacy of the original vaccines has waned and has required vaccine updating and boosting. Nevertheless, hospitalizations and deaths due to COVID-19 have remained low. In this review, we summarize current knowledge of immune responses that contribute to population immunity and the mechanisms how vaccines attenuate COVID-19 disease severity.

Development of an rpS6-Based Ex Vivo Assay for the Analysis of Neuronal Activity in Mouse and Human Olfactory Systems

Olfactory sensitivity to odorant molecules is a complex biological function influenced by both endogenous factors, such as genetic background and physiological state, and exogenous factors, such as environmental conditions. In animals, this vital ability is mediated by olfactory sensory neurons (OSNs), which are distributed across several specialized olfactory subsystems depending on the species. Using the phosphorylation of the ribosomal protein S6 (rpS6) in OSNs following sensory stimulation, we developed an ex vivo assay allowing the simultaneous conditioning and odorant stimulation of different mouse olfactory subsystems, including the main olfactory epithelium, the vomeronasal organ, and the Grueneberg ganglion. This approach enabled us to observe odorant-induced neuronal activity within the different olfactory subsystems and to demonstrate the impact of environmental conditioning, such as temperature variations, on olfactory sensitivity, specifically in the Grueneberg ganglion. We further applied our rpS6-based assay to the human olfactory system and demonstrated its feasibility. Our findings show that analyzing rpS6 signal intensity is a robust and highly reproducible indicator of neuronal activity across various olfactory systems, while avoiding stress and some experimental limitations associated with in vivo exposure. The potential extension of this assay to other conditioning paradigms and olfactory systems, as well as its application to other animal species, including human olfactory diagnostics, is also discussed.

Pathogenesis and virulence of coronavirus disease: Comparative pathology of animal models for COVID-19

Animal models that can replicate clinical and pathologic features of severe human coronavirus infections have been instrumental in the development of novel vaccines and therapeutics. The goal of this review is to summarize our current understanding of the pathogenesis of coronavirus disease 2019 (COVID-19) and the pathologic features that can be observed in several currently available animal models. Knowledge gained from studying these animal models of SARS-CoV-2 infection can help inform appropriate model selection for disease modelling as well as for vaccine and therapeutic developments.

Clonal landscape of autoantibody-secreting plasmablasts in COVID-19 patients

Whereas severe COVID-19 is often associated with elevated autoantibody titers, the underlying mechanism behind their generation has remained unclear. Here we report clonal composition and diversity of autoantibodies in humoral response to SARS-CoV-2. Immunoglobulin repertoire analysis and characterization of plasmablast-derived monoclonal antibodies uncovered clonal expansion of plasmablasts producing cardiolipin (CL)-reactive autoantibodies. Half of the expanded CL-reactive clones exhibited strong binding to SARS-CoV-2 antigens. One such clone, CoV1804, was reactive to both CL and viral nucleocapsid (N), and further showed anti-nucleolar activity in human cells. Notably, antibodies sharing genetic features with CoV1804 were identified in COVID-19 patient-derived immunoglobulins, thereby constituting a novel public antibody. These public autoantibodies had numerous mutations that unambiguously enhanced anti-N reactivity, when causing fluctuations in anti-CL reactivity along with the acquisition of additional self-reactivities, such as anti-nucleolar activity, in the progeny. Thus, potentially CL-reactive precursors may have developed multiple self-reactivities through clonal selection, expansion, and somatic hypermutation driven by viral antigens. Our results revealed the nature of autoantibody production during COVID-19 and provided novel insights into the origin of virus-induced autoantibodies.

Neuro-inflammatory pathways in COVID-19-induced central nervous system injury: Implications for prevention and treatment strategies

This review explores the neuroinflammatory pathways underlying COVID-19-induced central nervous system (CNS) injury, with a focus on mechanisms of brain damage and strategies for prevention. A comprehensive literature review was conducted to summarize current knowledge on the pathways by which SARS-CoV-2 reaches the brain, the neuroinflammatory responses triggered by viral infection, neurological symptoms and long COVID. Results: We discuss the mechanisms of neuroinflammation in COVID-19, including blood-brain barrier disruption, cytokine storm, microglial activation, and peripheral immune cell infiltration. Additionally, we highlight potential strategies for preventing CNS injury, including pharmacological interventions, immunomodulatory therapies, and lifestyle modifications. Conclusively, Understanding the neuroinflammatory pathways in COVID-19-induced CNS injury is crucial for developing effective prevention and treatment strategies to protect brain health during and after viral infection.

Visualizing the human olfactory projection and ancillary structures in a 3D reconstruction

Visualizing in 3D the histological microanatomy of the human olfactory projection from the olfactory mucosa in the nasal cavity to the olfactory bulbs in the cranial cavity necessitates a workflow for handling a great many sections. Here, we assembled a 3D reconstruction of a 7.45 cm3 en-bloc specimen extracted from an embalmed human cadaver. A series of 10 µm coronal sections was stained with quadruple fluorescence histology and scanned in four channels. A trained anatomist manually segmented six structures of interest in a subset of the sections to generate the ground truth. Six convolutional neural networks were then trained for automatic segmentation of these structures in 1234 sections. A high-performance computing solution was engineered to register the sections based on the fluorescence signal and segmented structures. The resulting 3D visualization offers several novel didactic opportunities of interactive exploration and virtual manipulation. By extrapolating manual counts of OSNs in a subset of sections to the calculated volume of the envelope of the entire olfactory epithelium, we computed a total of ~2.7 million OSNs in the specimen. Such empirically derived information helps assess the extent to which the organizational principles of the human olfactory projection may differ from those in mice.

Cardiovascular and kidney diseases are positively associated with neuroinflammation and reduced brain-derived neurotrophic factor in patients with severe COVID-19

Even though respiratory dysfunctions are the primary symptom associated with SARS-CoV-2 infection, cerebrovascular events, and neurological symptoms are described in many patients. However, the connection between the neuroimmune profile and the lung's inflammatory condition during COVID-19 and its association with the neurological symptoms reported by COVID-19 patients still needs further exploration. The present study characterizes the SARS-CoV-2 infectivity profile in postmortem nervous and lung tissue samples of patients who died due to severe COVID-19, and the pro-inflammatory factors present in both nervous and lung tissue samples, via a proteomic profiling array. Additionally, Brain-Derived Neurotrophic Factor (BDNF) levels and intracellular pathways related to neuroplasticity/neuroprotection were assessed in the samples. Out of the 16 samples analyzed, all samples but 1 were positive for the viral genome (genes E or N2, but only 3.9% presented E and N2) in the olfactory brain pathway. The E or N2 gene were also detected in all lung samples, with 43.7% of the samples being positive for the E and N2 genes. In the E/N2 positive brain samples, the Spike protein of SARS-CoV-2 co-localized with TUJ-1+ (neuron-specific class III beta-tubulin) and GFAP+ (glial fibrillary acidic protein) astrocytes. IL-6, but not IL-10, expression was markedly higher in most nervous tissue samples compared to the lung specimens. While intracellular adhesion molecule-1 (ICAM-1), interleukin-8 (IL-8), macrophage migration inhibitory factor (MIF), and plasminogen activator inhibitor 1 (PAI-1) were increased in lung samples from SARS-Cov-2 patients, only MIF and IL-18 were detected in nervous tissue samples. Correlation analysis suggested that high levels of IL-6 are followed by increased levels of IL-10 in the brain, but not in lung samples. Our analysis also demonstrated that the presence of comorbidities, such as cardiovascular disease, hypertension, and hypothyroidism, is associated with neuroinflammation, while chronic kidney conditions predict the presence of neurological symptoms, which correlate with lower levels of BDNF in the brain samples. Our results corroborate the hypothesis that a pro-inflammatory state might further impair neural homeostasis and induce brain abnormalities found in COVID-19 patients.

Cytoskeletal β-tubulin and cysteine cathepsin L deregulation by SARS-CoV-2 spike protein interaction with the neuronal model cell line SH-SY5Y

SARS-CoV-2 mainly infects the respiratory tract but can also target other organs, including the central nervous system. While it was recently shown that cells of the blood-brain-barrier are permissive to SARS-CoV-2 infection in vitro, it remains debated whether neurons can be infected. In this study, we demonstrate that vesicular stomatitis virus particles pseudotyped with the spike protein of SARS-CoV-2 variants WT, Alpha, Delta and Omicron enter the neuronal model cell line SH-SY5Y. Cell biological analyses of the pseudo-virus treated cultures showed marked alterations in microtubules of SH-SY5Y cells. Because the changes in β-tubulin occurred in most cells, but only few were infected, we further asked whether interaction of the cells with spike protein might be sufficient to cause molecular and structural changes. For this, SH-SY5Y cells were incubated with trimeric spike proteins for time intervals of up to 24 h. CellProfiler™-based image analyses revealed changes in the intensities of microtubule staining in spike protein-incubated cells. Furthermore, expression of the spike protein-processing protease cathepsin L was found to be up-regulated by wild type, Alpha and Delta spike protein pseudotypes and cathepsin L was found to be secreted from spike protein-treated cells. We conclude that the mere interaction of the SARS-CoV-2 with neuronal cells can affect cellular architecture and proteolytic capacities. The molecular mechanisms underlying SARS-CoV-2 spike protein induced cytoskeletal changes in neuronal cells remain elusive and require future studies.

A Large Postmortem Database of COVID-19 Patients Can Inform Disease Research and Public Policy Decision Making

CONTEXT.—

Autopsies performed on COVID-19 patients have provided critical information about SARS-CoV-2's tropism, mechanisms of tissue injury, and spectrum of disease.

OBJECTIVE.—

To provide an updated database of postmortem disease in COVID-19 patients, assess relationships among clinical and pathologic variables, evaluate the accuracy of death certification, and correlate disease variables to causes of death.

DESIGN.—

The 272 postmortem examinations reported in this paper were submitted by 14 pathologists from 9 medical or forensic institutions across the United States. The study spans the eras of the 3 principal COVID-19 strains and incorporates surveyed demographic, clinical, and postmortem data from decedents infected with SARS-CoV-2, including primary and contributing causes of death. It is the largest database of its kind to date.

RESULTS.—

Demographics of the decedents reported here correspond well to national statistics. Primary causes of death as determined by autopsy and official death certificates were significantly correlated. When specifically cited disease conditions found at autopsy were correlated with COVID-19 versus non-COVID-19 deaths, only lung findings characteristic of SARS-CoV-2 infection or the absence of lung findings were significantly associated.

CONCLUSIONS.—

Changes in hospitalization and disease likely stem from longer lifespans after COVID-19 diagnosis and alteration in treatment approaches. Although Omicron variants preferentially replicate in the upper airways, autopsied patients who died of COVID-19 in that time period showed the same lung damage as earlier decedents. Most importantly, findings suggest that there are still unelucidated risk factors for death from COVID-19 including possibly genetic susceptibility.

Treatment of COVID-19 Associated Olfactory Dysfunction: A Systematic Review

PURPOSE OF REVIEW

COVID -19 associated olfactory dysfunction is widespread, yet effective treatment strategies remain unclear. This article aims to provide a comprehensive systematic review of therapeutic approaches and offers evidence-based recommendations for their clinical application.

RECENT FINDINGS

A living Cochrane review, with rigorous inclusion criteria, has so far included 2 studies with a low certainty of evidence. In this systematic review we list clinical data of 36 randomised controlled trials (RCTs) and non-randomised studies published between Jan 1, 2020 and Nov 19, 2023 regarding treatment options for COVID-19 associated olfactory dysfunction. Nine treatment groups were analysed, including olfactory training, local and systemic corticosteroids, platelet-rich plasma (PRP), calcium chelators, vitamin supplements including palmitoylethanolamide with luteolin, insulin, gabapentin and cerebrolysin. Primary objective was the effect of the studied treatments on the delta olfactory function score (OFS) for objective/psychophysical testing. Treatments such as PRP and calcium chelators demonstrated significant improvements on OFS, whereas olfactory training and corticosteroids did not show notable efficacy for COVID-19 associated olfactory dysfunction.

Using Zebrafish to Study Multiciliated Cell Development and Disease States

Multiciliated cells (MCCs) serve many important functions, including fluid propulsion and chemo- and mechanosensing. Diseases ranging from rare conditions to the recent COVID-19 global health pandemic have been linked to MCC defects. In recent years, the zebrafish has emerged as a model to investigate the biology of MCCs. Here, we review the major events in MCC formation including centriole biogenesis and basal body docking. Then, we discuss studies on the role of MCCs in diseases of the brain, respiratory, kidney and reproductive systems, as well as recent findings about the link between MCCs and SARS-CoV-2. Next, we explore why the zebrafish is a useful model to study MCCs and provide a comprehensive overview of previous studies of genetic components essential for MCC development and motility across three major tissues in the zebrafish: the pronephros, brain ependymal cells and nasal placode. Taken together, here we provide a cohesive summary of MCC research using the zebrafish and its future potential for expanding our understanding of MCC-related disease states.

Effectiveness of an Infection Control Program Among the Ysleta del Sur Pueblo in Preventing COVID-19-Related Hospitalizations and Deaths

In response to the SARS-CoV-2 pandemic, the United States declared a state of emergency and implemented large-scale shutdowns and public health initiatives to prevent overwhelming public resources. The success of these prevention methods remains unresolved as restrictions and implementation varied from national, state, and local levels. Despite national and local regulations, individual adherence to preventative guidelines presented an additional layer of variability. Cases of COVID-19 continued to rise and fall over a two-year period on a national level, despite masking recommendations, ease of testing, and availability of vaccines. The Ysleta del Sur Pueblo is a Native American tribal community and sovereign nation located in El Paso, Texas. Speaking Rock Entertainment Center is a major business operated by the tribe, employing many tribal and non-tribal members from the El Paso area. Following nationwide re-openings of non-essential businesses, Speaking Rock implemented an infection control program with strict adherence to recommendations provided by the Center for Disease Control and Prevention (CDC) and additional disease control. This response would result in a fully vaccinated workforce within the wider community of El Paso, where the vaccination rate was less than 80%. Herein, we examine the efficacy of these measures and report on the success of the program resulting in zero hospitalizations or deaths compared with rates of 1 in 250 and 1 in 40, respectively, in the surrounding community.

Pulmonary SARS-CoV-2 infection leads to para-infectious immune activation in the brain

Neurological complications, including encephalopathy and stroke, occur in a significant proportion of COVID-19 cases but viral protein is seldom detected in the brain parenchyma. To model this situation, we developed a novel low-inoculum K18-hACE2 mouse model of SARS-CoV-2 infection during which active viral replication was consistently seen in mouse lungs but not in the brain. We found that several mediators previously associated with encephalopathy in clinical samples were upregulated in the lung, including CCL2, and IL-6. In addition, several inflammatory mediations, including CCL4, IFNγ, IL-17A, were upregulated in the brain, associated with microglial reactivity. Parallel in vitro experiments demonstrated that the filtered supernatant from SARS-CoV-2 virion exposed brain endothelial cells induced activation of uninfected microglia. This model successfully recreates SARS-CoV-2 virus-associated para-infectious brain inflammation which can be used to study the pathophysiology of the neurological complications and the identification of potential immune targets for treatment.

Comparative analyses of post-infectious olfactory dysfunction between COVID-19 and non-COVID-19 cases

To identify the differences between COVID-19-associated and non-COVID-19-associated olfactory dysfunction (OD), we analyzed demographic and clinical characteristics based on the causative virus (COVID versus non-COVID groups) in patients with post-infectious olfactory dysfunction (PIOD) who underwent the olfactory questionnaire and olfactory function test. Out of 169 patients with PIOD, 99 were diagnosed with COVID-19 (COVID group), while 70 were not (non-COVID group). The COVID group was younger and had a higher percentage of male patients as well as patients with parosmia than the non-COVID group. In the initial olfactory function tests, the TDI, discrimination and identification scores were significantly higher in the COVID group than in the non-COVID group. TDI scores were significantly increased in patients with PIOD after treatment, regardless of the group. The threshold score was significantly increased by 1.38 in the COVID group while the identification score was significantly increased by 2.67 in the non-COVID group. Patients with COVID-19-associated OD were younger in age, tended to be male, had a higher incidence of parosmia, and had better initial olfactory function test results compared to those with non-COVID-19-associated OD. Following treatment, odor detection threshold improved in the COVID group, whereas odor identification improved in the non-COVID group.

Aggravating mechanisms from COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces immune-mediated diseases. The pathophysiology of COVID-19 uses the following three mechanisms: (1) inflammasome activation mechanism; (2) cGAS-STING signaling mechanism; and (3) SAMHD1 tetramerization mechanism, which leads to IFN-I production. Interactions between the host and virus govern induction, resulting in multiorgan impacts. The NLRP3 with cGAS-STING constitutes the primary immune response. The expression of SARS-CoV-2 ORF3a, NSP6, NSP7, and NSP8 blocks innate immune activation and facilitates virus replication by targeting the RIG-I/MDA5, TRIF, and cGAS-STING signaling. SAMHD1 has a target motif for CDK1 to protect virion assembly, threonine 592 to modulate a catalytically active tetramer, and antiviral IFN responses to block retroviral infection. Plastic and allosteric nucleic acid binding of SAMHD1 modulates the antiretroviral activity of SAMHD1. Therefore, inflammasome activation, cGAS-STING signaling, and SAMHD1 tetramerization explain acute kidney injury, hepatic, cardiac, neurological, and gastrointestinal injury of COVID-19. It might be necessary to effectively block the pathological courses of diverse diseases.

Chronic Cough Related to Thyroid Cartilage Superior Cornu Abnormality

Chronic cough is a common troublesome symptom in otolaryngology head and neck surgery practice. In rare cases, chronic cough may be related to anatomical abnormalities. In this article, we report the history of a 64-year-old female with a chronic course due to a curved superior cornu of the thyroid cartilage and related irritation of the laryngeal superior nerve. The cough was atypical and resolved after the surgical resection of the abnormal cornu. There was no recurrence at 9 months post-surgery. The findings of the present case report highlight the need to explore the laryngeal anatomy in patients with chronic cough to identify potential abnormalities, which may be treated surgically.

A robust mouse model of HPIV-3 infection and efficacy of GS-441524 against virus-induced lung pathology

Human parainfluenza virus type 3 (HPIV-3) can cause severe respiratory tract infections. There are no convenient small-animal infection models. Here, we show viral replication in the upper and lower airways of AG129 mice (double IFNα/β and IFNγ receptor knockout mice) upon intranasal inoculation. By multiplex fluorescence RNAscope and immunohistochemistry followed by confocal microscopy, we demonstrate viral tropism to ciliated cells and club cells of the bronchiolar epithelium. HPIV-3 causes a marked lung pathology. No virus transmission of the virus was observed by cohousing HPIV-3-infected AG129 mice with other mice. Oral treatment with GS-441524, the parent nucleoside of remdesivir, reduced infectious virus titers in the lung, with a relatively normal histology. Intranasal treatment also affords an antiviral effect. Thus, AG129 mice serve as a robust preclinical model for developing therapeutic and prophylactic strategies against HPIV-3. We suggest further investigation of GS-441524 and its prodrug forms to treat HPIV-3 infection in humans.

Parosmia in patients with post-infectious olfactory dysfunction in the era of COVID-19-associated olfactory impairment

OBJECTIVES

A large number of patients with olfactory impairment are affected by parosmia or phantosmia. This study aimed to examine the demographic and clinical characteristics of parosmia.

METHODS

We performed a retrospective data analysis of patients consulting at our Smell and Taste Outpatient Clinic. A total of 297 patients were included (203 women, mean age 44.4 ± 13.7 years). Olfactory function was quantified using the "Sniffin' Sticks" composite TDI (odor threshold, determination, and identification) score. The presence of qualitative olfactory impairment was assessed trough medical history and a parosmia questionnaire.

RESULTS

Most of the patients showed olfactory impairment after an infection with SARS-CoV‑2 (84%) and were diagnosed with parosmia (49%). Patients with parosmia (PAR) (n = 201) were significantly younger compared to the group without parosmia (noPAR; n = 92) (PAR 43.2 ± 13 years vs. noPAR 47 ± 15.1 years, p = 0.03) and had a slightly shorter duration of disease, without reaching statistical significance (PAR 10.3 ± 4.9 months, noPAR 13.6 ± 37.6 months, p = 0.23). They also had higher TDI scores (PAR 24.3 ± 7 points, noPAR 21.4 ± 8.2 points, p = 0.003).

CONCLUSIONS

Patients affected by parosmia were younger and had a better olfactory function compared to patients without parosmia.

Comparison of sinonasal symptoms in upper respiratory tract infections during the infectious diseases season of November 2023 to March 2024-a cross-sectional study

Introduction

Upper respiratory tract infections (URTIs) are among the most common reasons for patients consulting a general practitioner (GP) during the infectious diseases season, with viruses being the predominant cause. The COVID-19 pandemic has significantly impacted GPs' perception of these infections. The pandemic's progression, especially with the emergence of the Omicron variant, has complicated the diagnosis and treatment of URTIs, with evolving symptoms.

Aim

The aim of this study was to assess the differences in symptoms reported by patients with various infections, such as COVID-19, influenza, common cold, and post-viral rhinosinusitis, during the infectious diseases season of November 2023 to March 2024.

Materials and methods

The study was conducted in a primary health care clinic, providing care for a population of approximately 10,000 people, among adult patients presenting with URTI symptoms during the 2023/2024 infectious diseases season. Patients qualified for the study were swabbed for SARS-CoV-2, influenza A and B and respiratory syncytial virus (RSV) antigens. Symptoms were assessed with the use of a semi-structured questionnaire.

Results

Of the 1810 patients presenting with symptoms of URTIs, 276 patients were included in the study. Among patients with COVID-19, symptoms of nasal obstruction (p = 0.005) and nasal discharge (p = 0.001) were less common than in those with influenza or common cold. However, these nasal symptoms were significantly more frequent among patients with COVID-19 who had confirmed previous immunization (COVID-19 history or vaccination) (p = 0.028).

Conclusion

The incidence of individual sinonasal symptoms varies significantly depending on the aetiological agent of the URTI. This observation may not only help clinicians make the correct diagnosis, but also suggests an inflammatory response in the nasal mucosa and paranasal sinuses that is dependent on the aetiological agent. The study also indicates that this response is altered within the same virus species following immunization.

Limitations

The study's limitations include a small sample size (276 patients), focus on one season and one GP practice, and reliance on clinical signs and antigen tests. Nonetheless, the findings provide valuable insights. Further research with larger patient groups and extended follow-up periods is required to confirm these findings.

Spatiotemporal omics for biology and medicine

The completion of the Human Genome Project has provided a foundational blueprint for understanding human life. Nonetheless, understanding the intricate mechanisms through which our genetic blueprint is involved in disease or orchestrates development across temporal and spatial dimensions remains a profound scientific challenge. Recent breakthroughs in cellular omics technologies have paved new pathways for understanding the regulation of genomic elements and the relationship between gene expression, cellular functions, and cell fate determination. The advent of spatial omics technologies, encompassing both imaging and sequencing-based methodologies, has enabled a comprehensive understanding of biological processes from a cellular ecosystem perspective. This review offers an updated overview of how spatial omics has advanced our understanding of the translation of genetic information into cellular heterogeneity and tissue structural organization and their dynamic changes over time. It emphasizes the discovery of various biological phenomena, related to organ functionality, embryogenesis, species evolution, and the pathogenesis of diseases.

The Interplay between Airway Cilia and Coronavirus Infection, Implications for Prevention and Control of Airway Viral Infections

Coronaviruses (CoVs) are a class of respiratory viruses with the potential to cause severe respiratory diseases by infecting cells of the upper respiratory tract, bronchial epithelium, and lung. The airway cilia are distributed on the surface of respiratory epithelial cells, forming the first point of contact between the host and the inhaled coronaviruses. The function of the airway cilia is to oscillate and sense, thereby defending against and removing pathogens to maintain the cleanliness and patency of the respiratory tract. Following infection of the respiratory tract, coronaviruses exploit the cilia to invade and replicate in epithelial cells while also damaging the cilia to facilitate the spread and exacerbation of respiratory diseases. It is therefore imperative to investigate the interactions between coronaviruses and respiratory cilia, as well as to elucidate the functional mechanism of respiratory cilia following coronavirus invasion, in order to develop effective strategies for the prevention and treatment of respiratory viral infections. This review commences with an overview of the fundamental characteristics of airway cilia, and then, based on the interplay between airway cilia and coronavirus infection, we propose that ciliary protection and restoration may represent potential therapeutic approaches in emerging and re-emerging coronavirus pandemics.

Receptors Involved in COVID-19-Related Anosmia: An Update on the Pathophysiology and the Mechanistic Aspects

Olfactory perception is an important physiological function for human well-being and health. Loss of olfaction, or anosmia, caused by viral infections such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has received considerable attention, especially in persistent cases that take a long time to recover. This review discusses the integration of different components of the olfactory epithelium to serve as a structural and functional unit and explores how they are affected during viral infections, leading to the development of olfactory dysfunction. The review mainly focused on the role of receptors mediating the disruption of olfactory signal transduction pathways such as angiotensin converting enzyme 2 (ACE2), transmembrane protease serine type 2 (TMPRSS2), neuropilin 1 (NRP1), basigin (CD147), olfactory, transient receptor potential vanilloid 1 (TRPV1), purinergic, and interferon gamma receptors. Furthermore, the compromised function of the epithelial sodium channel (ENaC) induced by SARS-CoV-2 infection and its contribution to olfactory dysfunction are also discussed. Collectively, this review provides fundamental information about the many types of receptors that may modulate olfaction and participate in olfactory dysfunction. It will help to understand the underlying pathophysiology of virus-induced anosmia, which may help in finding and designing effective therapies targeting molecules involved in viral invasion and olfaction. To the best of our knowledge, this is the only review that covered all the receptors potentially involved in, or mediating, the disruption of olfactory signal transduction pathways during COVID-19 infection. This wide and complex spectrum of receptors that mediates the pathophysiology of olfactory dysfunction reflects the many ways in which anosmia can be therapeutically managed.

Exploring viral neuropathic pain: Molecular mechanisms and therapeutic implications

As the Coronavirus Disease 2019 (COVID-19) pandemic continues, there is a growing concern regarding the relationship between viral infections and neuropathic pain. Chronic neuropathic pain resulting from virus-induced neural dysfunction has emerged as a significant issue currently faced. However, the molecular mechanisms underlying this phenomenon remain unclear, and clinical treatment outcomes are often suboptimal. Therefore, delving into the relationship between viral infections and neuropathic pain, exploring the pathophysiological characteristics and molecular mechanisms of different viral pain models, can contribute to the discovery of potential therapeutic targets and methods, thereby enhancing pain relief and improving the quality of life for patients. This review focuses on HIV-related neuropathic pain (HNP), postherpetic neuralgia (PHN), and neuropathic pain caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections, examining rodent models and relevant cellular molecular pathways. Through elucidating the connection between viral infections and neuropathic pain, it aims to delineate the current limitations and challenges faced by treatments, thereby providing insights and directions for future clinical practice and research.

Widespread Distribution of Luteinizing Hormone/Choriogonadotropin Receptor in Human Juvenile Angiofibroma: Implications for a Sex-Specific Nasal Tumor

Juvenile angiofibroma (JA) is a rare, sex-specific, and highly vascularized nasal tumor that almost exclusively affects male adolescents, but its etiology has been controversial. The G protein-coupled hormone receptor LHCGR [luteinizing hormone (LH)/choriogonadotropin (hCG) receptor] represents a promising new candidate for elucidating the underlying mechanisms of sex specificity, pubertal manifestation, and JA progression. We used highly sensitive RNAscope technology, together with immunohistochemistry, to investigate the cellular expression, localization, and distribution of LHCGR in tissue samples from JA patients. Our results provide evidence for LHCGR expression in subsets of cells throughout JA tissue sections, with the majority of LHCGR+ cells located in close vicinity to blood vessels, rendering them susceptible to endocrine LH/hCG signaling, but LHCGR+ cells were also detected in fibrocollagenous stroma. A majority of LHCGR+ cells located near the vascular lumen co-expressed the neural crest stem cell marker CD271. These results are intriguing as both LH and hCG are produced in a time- and sex-dependent manner, and are known to be capable of inducing cell proliferation and angiogenesis. Our results give rise to a new model that suggests endocrine mechanisms involving LHCGR and its ligands, together with autocrine and paracrine signaling, in JA vascularization and cell proliferation.

Impact of age and sex on neuroinflammation following SARS-CoV-2 infection in a murine model

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, is known to infect people of all ages and both sexes. Senior populations have the greatest risk of severe COVID-19, and sexual dimorphism in clinical outcomes has been reported. Neurological symptoms are widely observed in COVID-19 patients, with many survivors exhibiting persistent neurological and cognitive impairment. The present study aims to investigate the impact of age and sex on the neuroinflammatory response to SARS-CoV-2 infection using a mouse model. Wild-type C57BL/6J mice were intranasally inoculated with SARS-CoV-2 lineage B.1.351, a variant known to infect mice. Older male mice exhibited a significantly greater weight loss and higher viral loads in the lung at 3 days post infection. Notably, no viral RNA was detected in the brains of infected mice. Nevertheless, expression of IL-6, TNF-α, and CCL-2 in the lung and brain increased with viral infection. RNA-seq transcriptomic analysis of brains showed that SARS-CoV-2 infection caused significant changes in gene expression profiles, implicating innate immunity, defense response to virus, and cerebrovascular and neuronal functions. These findings demonstrate that SARS-CoV-2 infection triggers a neuroinflammatory response, despite the lack of detectable virus in the brain. Aberrant activation of innate immune response, disruption of blood-brain barrier and endothelial cell integrity, and suppression of neuronal activity and axonogenesis underlie the impact of SARS-CoV-2 infection on the brain. Understanding the role of these affected pathways in SARS-CoV-2 pathogenesis helps identify appropriate points of therapeutic interventions to alleviate neurological dysfunction observed during COVID-19.

Basic implications on three pathways associated with SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) interacts between the host and virus and govern induction, resulting in multiorgan impacts. Its pathophysiology involves the followings: 1) the angiotensin-converting enzyme (ACE2) and Toll-like receptor (TLR) pathways: 2) the neuropilin (NRP) pathway: 3) the spike protein pathway. Therefore, it is necessary to block the pathological course with modulating innate lymphoid cells against diverse corona variants in the future.

Persistent COVID-19 parosmia and olfactory loss post olfactory training: randomized clinical trial comparing central and peripheral-acting therapeutics

PURPOSE

Although COVID-19 anosmia is often transient, patients with persistent olfactory dysfunction (pOD) can experience refractory parosmia and diminished smell. This study evaluated four putative therapies for parosmia in patients with chronic COVID-19 olfactory impairment.

METHODS

After screening nasal endoscopy, 85 patients (49 female, 58%) with pOD and treatment-refractory parosmia were randomized to: (1) ultramicronized palmitoylethanolamide and luteolin + olfactory training (OT) (umPEALUT group, n = 17), (2) alpha-lipoic acid + OT (ALA group, n = 21), (3) umPEALUT + ALA + OT (combination group, n = 28), or 4) olfactory training (OT) alone (control group, n = 23). Olfactory function was assessed at baseline (T0) and 6 months (T1) using a parosmia questionnaire and Sniffin' Sticks test of odor threshold, detection, and identification (TDI). Analyses included one-way ANOVA for numeric data and Chi-Square analyses for nominal data on parosmia.

RESULTS

The umPEALUT group had the largest improvement in TDI scores (21.8 ± 9.4 to 29.7 ± 7.5) followed by the combination group (19.6 ± 6.29 to 27.5 ± 2.7), both p < 0.01. The control and ALA groups had no significant change. Patients in the combination and umPEALUT groups had significantly improved TDI scores compared to ALA and control groups (p < 0.001). Rates of parosmia resolution after 6 months were reported at 96% for combination, 65% for control, 53% for umPEALUT and 29% for ALA (p < 0.001). All treatment regimens were well-tolerated.

CONCLUSIONS

umPEALUT and OT, with or without ALA, was associated with improvement in TDI scores and parosmia, whereas OT alone or OT with ALA were associated with little benefit.

SARS-CoV-2: pathogenesis, therapeutics, variants, and vaccines

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in December 2019 with staggering economic fallout and human suffering. The unique structure of SARS-CoV-2 and its underlying pathogenic mechanism were responsible for the global pandemic. In addition to the direct damage caused by the virus, SARS-CoV-2 triggers an abnormal immune response leading to a cytokine storm, culminating in acute respiratory distress syndrome and other fatal diseases that pose a significant challenge to clinicians. Therefore, potential treatments should focus not only on eliminating the virus but also on alleviating or controlling acute immune/inflammatory responses. Current management strategies for COVID-19 include preventative measures and supportive care, while the role of the host immune/inflammatory response in disease progression has largely been overlooked. Understanding the interaction between SARS-CoV-2 and its receptors, as well as the underlying pathogenesis, has proven to be helpful for disease prevention, early recognition of disease progression, vaccine development, and interventions aimed at reducing immunopathology have been shown to reduce adverse clinical outcomes and improve prognosis. Moreover, several key mutations in the SARS-CoV-2 genome sequence result in an enhanced binding affinity to the host cell receptor, or produce immune escape, leading to either increased virus transmissibility or virulence of variants that carry these mutations. This review characterizes the structural features of SARS-CoV-2, its variants, and their interaction with the immune system, emphasizing the role of dysfunctional immune responses and cytokine storm in disease progression. Additionally, potential therapeutic options are reviewed, providing critical insights into disease management, exploring effective approaches to deal with the public health crises caused by SARS-CoV-2.

Reduced olfactory bulb volume accompanies olfactory dysfunction after mild SARS-CoV-2 infection

Despite its high prevalence, the determinants of smelling impairment in COVID-19 remain not fully understood. In this work, we aimed to examine the association between olfactory bulb volume and the clinical trajectory of COVID-19-related smelling impairment in a large-scale magnetic resonance imaging (MRI) analysis. Data of non-vaccinated COVID-19 convalescents recruited within the framework of the prospective Hamburg City Health Study COVID Program between March and December 2020 were analyzed. At baseline, 233 participants underwent MRI and neuropsychological testing as well as a structured questionnaire for olfactory function. Between March and April 2022, olfactory function was assessed at follow-up including quantitative olfactometric testing with Sniffin' Sticks. This study included 233 individuals recovered from mainly mild to moderate SARS-CoV-2 infections. Longitudinal assessment demonstrated a declining prevalence of self-reported olfactory dysfunction from 67.1% at acute infection, 21.0% at baseline examination and 17.5% at follow-up. Participants with post-acute self-reported olfactory dysfunction had a significantly lower olfactory bulb volume at baseline than normally smelling individuals. Olfactory bulb volume at baseline predicted olfactometric scores at follow-up. Performance in neuropsychological testing was not significantly associated with the olfactory bulb volume. Our work demonstrates an association of long-term self-reported smelling dysfunction and olfactory bulb integrity in a sample of individuals recovered from mainly mild to moderate COVID-19. Collectively, our results highlight olfactory bulb volume as a surrogate marker that may inform diagnosis and guide rehabilitation strategies in COVID-19.

Persistent Neurological Deficits in Mouse PASC Reveal Antiviral Drug Limitations

Post-Acute Sequelae of COVID-19 (PASC) encompasses persistent neurological symptoms, including olfactory and autonomic dysfunction. Here, we report chronic neurological dysfunction in mice infected with a virulent mouse-adapted SARS-CoV-2 that does not infect the brain. Long after recovery from nasal infection, we observed loss of tyrosine hydroxylase (TH) expression in olfactory bulb glomeruli and neurotransmitter levels in the substantia nigra (SN) persisted. Vulnerability of dopaminergic neurons in these brain areas was accompanied by increased levels of proinflammatory cytokines and neurobehavioral changes. RNAseq analysis unveiled persistent microglia activation, as found in human neurodegenerative diseases. Early treatment with antivirals (nirmatrelvir and molnupiravir) reduced virus titers and lung inflammation but failed to prevent neurological abnormalities, as observed in patients. Together these results show that chronic deficiencies in neuronal function in SARS-CoV-2-infected mice are not directly linked to ongoing olfactory epithelium dysfunction. Rather, they bear similarity with neurodegenerative disease, the vulnerability of which is exacerbated by chronic inflammation.

The physiological roles of anoctamin2/TMEM16B and anoctamin1/TMEM16A in chemical senses

Chemical senses allow animals to detect and discriminate a vast array of molecules. The olfactory system is responsible of the detection of small volatile molecules, while water dissolved molecules are detected by taste buds in the oral cavity. Moreover, many animals respond to signaling molecules such as pheromones and other semiochemicals through the vomeronasal organ. The peripheral organs dedicated to chemical detection convert chemical signals into perceivable information through the employment of diverse receptor types and the activation of multiple ion channels. Two ion channels, TMEM16B, also known as anoctamin2 (ANO2) and TMEM16A, or anoctamin1 (ANO1), encoding for Ca2+-activated Cl¯ channels, have been recently described playing critical roles in various cell types. This review aims to discuss the main properties of TMEM16A and TMEM16B-mediated currents and their physiological roles in chemical senses. In olfactory sensory neurons, TMEM16B contributes to amplify the odorant response, to modulate firing, response kinetics and adaptation. TMEM16A and TMEM16B shape the pattern of action potentials in vomeronasal sensory neurons increasing the interspike interval. In type I taste bud cells, TMEM16A is activated during paracrine signaling mediated by ATP. This review aims to shed light on the regulation of diverse signaling mechanisms and neuronal excitability mediated by Ca-activated Cl¯ channels, hinting at potential new roles for TMEM16A and TMEM16B in the chemical senses.