The spike protein of SARS-CoV-2 induces endothelial inflammation through integrin α5β1 and NF-κB signaling

New insights on the protection of endangered aquatic species: Embryotoxicity effects of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) via integrin-mediated oxidative stress and inflammatory pathways in Siberian sturgeon, Acipenser baerii

Polybrominated diphenyl ethers (PBDEs), are emerging pollutants ubiquitous in the environment, posing a threat to aquatic ecosystems. This study investigates the toxicological effects of PBDEs on sturgeon embryos, focusing on BDE-47, a representative PBDEs homologues. Siberian sturgeon embryos were exposed to BDE-47, revealing significant reductions in hatching and survival rates and the occurrence of developmental abnormalities. Oxidative stress induction by BDE-47 was evidenced by increased antioxidant enzyme activities and the presence of oxidative damage biomarker MDA. Besides, transcriptome analysis unveiled the activation of integrin signaling pathways, with molecular docking indicating strong binding to integrin receptors (specifically ITG-α5, ITG-α8, and ITG-α11). Moreover, qPCR and correlation analysis showed that BDE-47 significantly upregulated inflammatory cytokines and keap1/nrf2 signaling through ITGs. Furthermore, cultivation of head kidney macrophages showed that ITGs antagonist Cilengitide significantly reversed the upregulation of the above factors induced by BDE-47, including nf-κb, il-6, tnf-α, gpx, and nrf2. These findings indicate that BDE-47 induced embryotoxicity in Siberian sturgeon, which was potentially via ITGs-mediated oxidative stress and inflammatory pathways. This study providing novel insights into the protein binding of BDE-47 in animals, contributes to understanding emerging pollutant toxicity in fish embryos and offering a new perspective for the improvement of hatchability and survival rate of cultured sturgeon embryos to guarantee the sustainable development of the sturgeon aquaculture industry, as well as providing evidence for wild sturgeon populations conservation and habitat restoration.

The antiangiogenic peptide VIAN-c4551 inhibits lung melanoma metastasis in mice by reducing pulmonary vascular permeability

INTRODUCTION

Cancer cells drive the increase in vascular permeability mediating tumor cell extravasation and metastatic seeding. VIAN-c4551, an antiangiogenic peptide analog of vasoinhibin, inhibits the growth and vascularization of melanoma tumors in mice. Because VIAN-c4551 is a potent inhibitor of vascular permeability, we evaluated whether its antitumor action extended to a reduction in metastasis generation.

METHODS

Circulating levels of vascular endothelial growth factor (VEGF), lung vascular permeability, melanoma cell extravasation, and melanoma pulmonary nodules were assessed in C57BL/6J mice intravenously inoculated with murine melanoma B16-F10 cells after acute treatment with VIAN-c4551. VEGF levels, transendothelial electrical resistance, and transendothelial migration in cocultures of B16-F10 cells and endothelial cell monolayers supported the findings.

RESULTS

B16-F10 cells increased circulating VEGF levels and elevated lung vascular permeability 2 hours after inoculation. VIAN-c4551 prevented enhanced vascular permeability and reduced melanoma cell extravasation after 2 hours and the number and size of macroscopic and microscopic melanoma tumors in lungs after 17 days. In vitro, VIAN-c4551 suppressed the B16-F10 cell-induced and VEGF mediated increase in endothelial cell monolayer permeability and the transendothelial migration of B16-F10 cells. No detrimental effect of VIAN-c4551 was observed on hematological, biochemical, and histological parameters after its intravenous administration in mice for 14 days.

CONCLUSIONS

These findings support the inhibition of distant vascular permeability for the prevention of tumor metastasis and unveil the anti-vascular permeability factor VIAN-c4551 as a potential and safe therapeutic drug able to prevent metastasis generation by lowering the extravasation of melanoma cells.

The characteristics of multimodal fundus imaging in AMN patients following COVID infection

We investigated the features of multimodal fundus imaging in patients with both Coronavirus disease 2019 (COVID-19) and acute macular neuroretinopathy (AMN). This study included 15 patients with 29 eyes, all of whom underwent comprehensive fundus examinations and were followed for 3 months. Based on the diagnosis, patients were categorized into the AMN group and the AMN_PAMM group (AMN combined with paracentral acute middle maculopathy [PAMM]). At baseline, outer nuclear layer (ONL) thickness was not decreased in either group. However, a notable reduction in both outer retinal and full retinal thickness was observed in the AMN_PAMM group but not in the AMN group. Optical coherence tomography angiography (OCTA) demonstrated decreased vessel density (VD) in the intermediate capillary plexus (ICP) and deep capillary plexus (DCP), whereas the VD of the radial peripapillary capillary plexus (RPCP) and superficial vascular plexus (SVP) was increased in both groups. After 3 months of follow-up, ONL thickness and both outer and full retinal thickness were decreased in both groups. The VD of RPCP and SVP showed a significant decrease in the AMN_PAMM group. Visual acuity improvement was observed only in the AMN group, which may be attributed to the increase in choroid vascular index (CVI).

SARS-CoV-2 Spike Protein and Long COVID-Part 1: Impact of Spike Protein in Pathophysiological Mechanisms of Long COVID Syndrome

SARS-CoV-2 infection has resulted in more than 700 million cases and nearly 7 million deaths worldwide. Although vaccination efforts have effectively reduced mortality and transmission rates, a significant proportion of recovered patients-up to 40%-develop long COVID syndrome (LC) or post-acute sequelae of COVID-19 infection (PASC). LC is characterized by the persistence or emergence of new symptoms following initial SARS-CoV-2 infection, affecting the cardiovascular, neurological, respiratory, gastrointestinal, reproductive, and immune systems. Despite the broad range of clinical symptoms that have been described, the risk factors and pathogenic mechanisms behind LC remain unclear. This review, the first of a two-part series, is distinguished by the discussion of the role of the SARS-CoV-2 spike protein in the primary mechanisms underlying the pathophysiology of LC.

SARS-CoV-2 Spike Protein and Long COVID-Part 2: Understanding the Impact of Spike Protein and Cellular Receptor Interactions on the Pathophysiology of Long COVID Syndrome

SARS-CoV-2 infection has had a significant impact on global health through both acute illness, referred to as coronavirus disease 2019 (COVID-19), and chronic conditions (long COVID or post-acute sequelae of COVID-19, PASC). Despite substantial advancements in preventing severe COVID-19 cases through vaccination, the rise in the prevalence of long COVID syndrome and a notable degree of genomic mutation, primarily in the S protein, underscores the necessity for a deeper understanding of the underlying pathophysiological mechanisms related to the S protein of SARS-CoV-2. In this review, the latest part of this series, we investigate the potential pathophysiological molecular mechanisms triggered by the interaction between the spike protein and cellular receptors. Therefore, this review aims to provide a differential and focused view on the mechanisms potentially activated by the binding of the spike protein to canonical and non-canonical receptors for SARS-CoV-2, together with their possible interactions and effects on the pathogenesis of long COVID.

Exploring Integrin α5β1 as a Potential Therapeutic Target for Pulmonary Arterial Hypertension: Insights From Comprehensive Multicenter Preclinical Studies

BACKGROUND

Pulmonary arterial hypertension (PAH) is characterized by obliterative vascular remodeling of the small pulmonary arteries (PAs) and progressive increase in pulmonary vascular resistance leading to right ventricular failure. Although several drugs are approved for the treatment of PAH, mortality rates remain high. Accumulating evidence supports a pathological function of integrins in vessel remodeling, which are gaining renewed interest as drug targets. However, their role in PAH remains largely unexplored.

METHODS

The expression of the RGD (arginylglycylaspartic acid)-binding integrin α5β1 was assessed in PAs, PA smooth muscle cells, and PA endothelial cells from patients with PAH and controls using NanoString, immunoblotting, and Mesoscale Discovery assays. RNA sequencing was conducted to identify gene networks regulated by α5β1 inhibition in PAH PA smooth muscle cells. The therapeutic efficacy of α5β1 inhibition was evaluated using a novel small molecule inhibitor and selective neutralizing antibodies in Sugen/hypoxia and monocrotaline rat models, with validation by an external contract research organization. Comparisons were made against standard-of-care therapies (ie, macitentan, tadalafil) and sotatercept and efficacy was assessed using echocardiographic, hemodynamic, and histological assessments. Ex vivo studies using human precision-cut lung slices were performed to further assess the effects of α5β1 inhibition on pulmonary vascular remodeling.

RESULTS

We found that the arginine-glycine-aspartate RGD-binding integrin α5β1 is upregulated in PA endothelial cells and PA smooth muscle cells from patients with PAH and remodeled PAs from animal models. Blockade of the integrin α5β1 or depletion of the α5 subunit downregulated FOXM1 (forkhead box protein M1)-regulated gene networks, resulting in mitotic defects and inhibition of the pro-proliferative and apoptosis-resistant phenotype of PAH cells. We demonstrated that α5β1 integrin blockade safely attenuates pulmonary vascular remodeling and improves hemodynamics and right ventricular function and matched or exceeded the efficacy of standard of care and sotatercept in multiple preclinical models. Ex vivo studies further validated its potential in reversing advanced remodeling in human precision-cut lung slices.

CONCLUSIONS

These findings establish α5β1 integrin as a pivotal driver of PAH pathology and we propose its inhibition as a novel, safe, and effective therapeutic strategy for PAH.

The influence of SARS-CoV-2 spike protein exposure on retinal development in the human retinal organoids

BACKGROUND

Pregnant women are considered a high-risk population for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, as the virus can infect the placenta and embryos. Recently, SARS-CoV-2 has been widely reported to cause retinal pathological changes and to infect the embryonic retina. The infection of host cells by SARS-CoV-2 is primarily mediated through spike (S) protein, which also plays a crucial role in the pathogenesis of SARS-CoV-2. However, it remains poorly understood how the S protein of SARS-CoV-2 affects retinal development, and the underlying mechanism has not yet been clarified.

METHODS

We used human embryonic stem cell-derived retinal organoids (hEROs) as a model to study the effect of S protein exposure at different stages of retinal development. hEROs were treated with 2 μg/mL of S protein on days 90 and 280. Immunofluorescence staining, RNA sequencing, and RT-PCR were performed to assess the influence of S protein exposure on retinal development at both early and late stages.

RESULTS

The results showed that ACE2 and TMPRSS2, the receptors facilitating SARS-CoV-2 entry into host cells, were expressed in hEROs. Exposure to the S protein induced an inflammatory response in both the early and late stages of retinal development in the hEROs. Additionally, RNA sequencing indicated that early exposure of the S protein to hEROs affected nuclear components and lipid metabolism, while late-stages exposure resulted in changes to cell membrane components and the extracellular matrix.

CONCLUSION

This work highlights the differential effects of SARS-CoV-2 S protein exposure on retinal development at both early and late stages, providing insights into the cellular and molecular mechanisms underlying SARS-CoV-2-induced developmental impairments in the human retina.

Cerebral Hemodynamic Alterations in Dialysis COVID-19 Survivors: A Transcranial Doppler Ultrasound Study on Intracranial Pressure Dynamics

Background

We observed a COVID-19 survivor with a ventriculoperitoneal shunt who developed increased intracranial pressure during hemodialysis. We hypothesized that post-SARS-CoV-2 infection, patients may have altered cerebral perfusion pressure regulation in response to intracranial pressure changes.

Methods

From April to July 2021, we recruited dialysis patients with prior COVID-19 from two Madrid nephrology departments. We also recruited age- and sex-matched dialysis patients without prior SARS-CoV-2 infection. Transcranial Doppler ultrasound was used to measure the middle cerebral artery velocity before dialysis and 30, 60, and 90 min after the initiation of dialysis.

Results

The final sample included 37 patients (16 post-COVID-19 and 21 without). The COVID-19 survivors showed a significant pulsatility index increase between 30 and 60 min compared to those without COVID-19. They also had lower heart rates.

Conclusions

We propose two mechanisms: an increase in intracranial pressure or a decreased arterial elasticity. A lower heart rate was also observed in the COVID-19 survivors. This study highlights SARS-CoV-2's multifaceted effects, including potential long-term vascular and cerebral repercussions.

Carbon monoxide inhibits human bronchial epithelial CCL5 and IL-6 secretion induced by SARS-CoV-2 spike RBD protein

Carbon monoxide (CO) is a novel anti-inflammatory molecule, but the effects of CO on SARS-CoV-2 spike RBD (S-RBD)-induced human bronchial epithelial cytokines release remains unclear. CO was delivered using CO-releasing molecule 3 (CORM-3). The effects of S-RBD, ATPγS and CO on cytokines secretion were determined by enzyme-linked immunosorbent assay (ELISA) in 16HBE14o-human bronchial epithelial cell line. The inhibitory effect of CO on S-RBD-induced ERK phosphorylation was assessed by Western blot analysis. The regulatory effect of CO on extracellular nucleotide-induced ion transport was quantified by short-circuit current (ISC). S-RBD evoked CCL5 and IL-6 release and this effect could be suppressed by CO. However, CO failed to inhibit ATP release induced by S-RBD while decreased ATP-induced CCL5 and IL-6 secretion as well as ion transport. Furthermore, CO significantly inhibited ERK phosphorylation induced by S-RBD. These findings suggest an anti-inflammatory role of CO during inflammation induced by S-RBD and extracellular nucleotide in human bronchiol epithelial cells.

Primed Mesenchymal Stem Cells by IFN-γ and IL-1β Ameliorate Acute Respiratory Distress Syndrome through Enhancing Homing Effect and Immunomodulation

Acute Respiratory Distress Syndrome (ARDS) is a severe condition characterized by extensive lung inflammation and increased alveolar-capillary permeability, often triggered by infections or systemic inflammatory responses. Mesenchymal stem cells (MSCs)-based therapy holds promise for treating ARDS, as MSCs manifest immunomodulatory and regenerative properties that mitigate inflammation and enhance tissue repair. Primed MSCs, modified to augment specific functionalities, demonstrate superior therapeutic efficacy in targeted therapies compared to naive MSCs. This study explored the immunomodulatory potential of MSCs using mixed lymphocyte reaction (MLR) assays and co-culture experiments with M1/M2 macrophages. Additionally, RNA sequencing was employed to identify alterations in immune and inflammation-related factors in primed MSCs. The therapeutic effects of primed MSCs were assessed in an LPS-induced ARDS mouse model, and the underlying mechanisms were investigated through spatial transcriptomics analysis. The study revealed that MSCs primed with IFN-γ and IL-1β significantly enhanced the suppression of T cell activity compared to naive MSCs, concurrently inhibiting TNF-α while increasing IL-10 production in macrophages. Notably, combined treatment with these two cytokines resulted in a significant upregulation of immune and inflammation-regulating factors. Furthermore, our analyses elucidated the mechanisms behind the therapeutic effects of primed MSCs, including the inhibition of inflammatory cell infiltration in lung tissue, modulation of immune and inflammatory responses, and enhancement of elastin fiber formation. Signaling pathway analysis confirmed that efficacy could be enhanced by modulating NFκB and TNF-α signaling. In conclusion, in early-phase ARDS, primed MSCs displayed enhanced homing capabilities, improved lung function, and reduced inflammation.

Understanding the Impact of SARS-CoV-2 on Lung Endothelial Cells: Brief Mechanisms Unveiled

As the world grapples with the coronavirus-19 (COVID) pandemic, more reports are coming in regarding Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in endotheliopathy. It is a vascular condition in which endothelial cell injury or damage inflicts anatomical and functional changes in the endothelium, significantly impacting the physiological process and function. Previously, it was assumed that SARS-CoV-2 infects respiratory epithelial cells via spike glycoproteins present on the surface of the virus. However, severe cases and different autopsy studies described the clandestine role of this virus in infecting endothelial cells other than epithelial cells. It was observed that SARS-CoV-2 targets the pulmonary and extrapulmonary systems to damage the microvasculature and affect respiratory functioning, resulting in the onset of endotheliopathy, thrombosis, inflammation, pulmonary edema, and fibrosis. Such deleterious events are the consequence of the hyperactive immune response initiated by the SARS-CoV-2 infection, leading to pulmonary and extrapulmonary complications. However, the molecular mechanism behind endotheliopathy and other complications caused by this virus is elusive and will be unraveled by covering recent literature in this mini-review.

The COVID-19 thrombus: distinguishing pathological, mechanistic, and phenotypic features and management

A heightened risk for thrombosis is a hallmark of COVID-19. Expansive clinical experience and medical literature have characterized small (micro) and large (macro) vessel involvement of the venous and arterial circulatory systems. Most events occur in patients with serious or critical illness in the hyperacute (first 1-2 weeks) or acute phases (2-4 weeks) of SARS-CoV-2 infection. However, thrombosis involving the venous, arterial, and microcirculatory systems has been reported in the subacute (4-8 weeks), convalescent (> 8-12 weeks) and chronic phases (> 12 weeks) among patients with mild-to-moderate illness. The purpose of the current focused review is to highlight the distinguishing clinical features, pathological components, and potential mechanisms of venous, arterial, and microvascular thrombosis in patients with COVID-19. The overarching objective is to better understand the proclivity for thrombosis, laying a solid foundation for screening and surveillance modalities, preventive strategies, and optimal patient management.

Sustained Vascular Inflammatory Effects of SARS-CoV-2 Spike Protein on Human Endothelial Cells

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been associated with systemic inflammation and vascular injury, which contribute to the development of acute respiratory syndrome (ARDS) and the mortality of COVID-19 infection. Moreover, multiorgan complications due to persistent endothelial dysfunction have been suspected as the cause of post-acute sequelae of SARS-CoV-2 infection. Therefore, elucidation of the vascular inflammatory effect of SARS-CoV-2 will increase our understanding of how endothelial cells (ECs) contribute to the short- and long-term consequences of SARS-CoV-2 infection. Here, we investigated the interaction of SARS-CoV-2 spike protein with human ECs from aortic (HAoEC) and pulmonary microvascular (HPMC) origins, cultured under physiological flow conditions. We showed that the SARS-CoV-2 spike protein triggers prolonged expression of cell adhesion markers in both ECs, similar to the effect of TNF-α. SARS-CoV-2 spike treatment also led to the release of various cytokines and chemokines observed in severe COVID-19 patients. Moreover, increased binding of leucocytes to the endothelial surface and a procoagulant state of the endothelium were observed. Transcriptomic profiles of SARS-CoV-2 spike-activated HPMC and HAoEC showed prolonged upregulation of genes and pathways associated with responses to virus, cytokine-mediated signaling, pattern recognition, as well as complement and coagulation pathways. Our findings support experimental and clinical observations of the vascular consequences of SARS-CoV-2 infection and highlight the importance of EC protection as one of the strategies to mitigate the severe effects as well as the possible post-acute complications of COVID-19 disease.

The Immunologic Downsides Associated with the Powerful Translation of Current COVID-19 Vaccine mRNA Can Be Overcome by Mucosal Vaccines

The action of mRNA-based vaccines requires the expression of the antigen in cells targeted by lipid nanoparticle-mRNA complexes. When the vaccine antigen is not fully retained by the producer cells, its local and systemic diffusion can have consequences depending on both the levels of antigen expression and its biological activity. A peculiarity of mRNA-based COVID-19 vaccines is the extraordinarily high amounts of the Spike antigen expressed by the target cells. In addition, vaccine Spike can be shed and bind to ACE-2 cell receptors, thereby inducing responses of pathogenetic significance including the release of soluble factors which, in turn, can dysregulate key immunologic processes. Moreover, the circulatory immune responses triggered by the vaccine Spike is quite powerful, and can lead to effective anti-Spike antibody cross-binding, as well as to the emergence of both auto- and anti-idiotype antibodies. In this paper, the immunologic downsides of the strong efficiency of the translation of the mRNA associated with COVID-19 vaccines are discussed together with the arguments supporting the idea that most of them can be avoided with the advent of next-generation, mucosal COVID-19 vaccines.

Phytoconstituents as modulator of inflammatory pathways for COVID-19: A comprehensive review and recommendations

SARS-CoV-2 infection causes disruptions in inflammatory pathways, which fundamentally contribute to COVID-19 pathophysiology. The present review critically evaluates the gaps in scientific literature and presents the current status regarding the inflammatory signaling pathways in COVID-19. We propose that phytoconstituents can be used to treat COVID-19 associated inflammation, several already formulated in traditional medications. For this purpose, extensive literature analysis was conducted in the PubMed database to collect relevant in vitro, in vivo, and human patient studies where inflammation pathways were shown to be upregulated in COVID-19. Parallelly, scientific literature was screened for phytoconstituents with known cellular mechanisms implicated for inflammation or COVID-19 associated inflammation. Studies with insufficient evidence on cellular pathways for autophagy and mitophagy were considered out of scope and excluded from the study. The final analysis was visualized in figures and evaluated for accuracy. Our findings demonstrate the frequent participation of NF-κB, a transcription factor, in inflammatory signaling pathways linked to COVID-19. Moreover, the MAPK signaling pathway is also implicated in producing inflammatory molecules. Furthermore, it was also analyzed that the phytoconstituents with flavonoid and phenolic backbones could inhibit either the TLR4 receptor or its consecutive signaling molecules, thereby, decreasing NF-κB activity and suppressing cytokine production. Although, allopathy has treated the early phase of COVID-19, anti-inflammatory phytoconstituents and existing ayurvedic formulations may act on the COVID-19 associated inflammatory pathways and provide an additional treatment strategy. Therefore, we recommend the usage of flavonoids and phenolic phytoconstituents for the treatment of inflammation associated with COVID-19 infection and similar viral ailments.

The SARS-unique domain (SUD) of SARS-CoV-2 nsp3 protein inhibits the antiviral immune responses through the NF-κB pathway

Nuclear factor κB (NF-κB) plays a crucial role in various cellular processes, including inflammatory and immune responses. Its activation is tightly regulated by the IKK (IκB kinase) complex. Upon severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the virus is initially recognized by the innate immune system and typically activates the NF-κB pathway, leading to a severe inflammatory response. However, the influence of viral proteins upon pro-inflammatory pathway is complicated. Here, we demonstrated that the viral protein nsp3 of SARS-CoV-2 exhibits an unusual function, which attenuated the NF-κB-mediated inflammatory response against SARS-CoV-2 infection in a unique manner. nsp3 interacted with the essential NF-κB modulator NEMO/IKKγ and promoted its polyubiquitylation via the E3 ubiquitin ligase CBL (Cbl Proto-Oncogene). Consequently, polyubiquitylated NEMO undergoes proteasome-dependent degradation, which disrupts NF-κB activation. Moreover, we found that the SARS unique domain (SUD) in nsp3 of SARS-CoV-2 is essential for inducing NEMO degradation, whereas this function is absent in SUD of SARS-CoV. The reduced activation of pro-inflammatory response at an early stage could mask the host immune response and faciliate excessive viral replication. Conversely, this finding may partially explain why SARS-CoV-2 causes a less inflammatory reaction than SARS-CoV, resulting in more mild or moderate COVID-19 cases and greater transmissibility. Given that NEMO is important for NF-κB activation, we propose that inhibiting polyubiquitylation and degradation of NEMO upon SARS-CoV-2 infection is a novel strategy to modulate the host inflammatory response.

SARS-CoV-2 uses Spike glycoprotein to control the host's anaerobic metabolism by inhibiting LDHB

The SARS-CoV-2 pandemic, responsible for approximately 7 million deaths worldwide, highlights the urgent need to understand the molecular mechanisms of the virus in order to prevent future outbreaks. The Spike glycoprotein of SARS-CoV-2, which is critical for viral entry through its interaction with ACE2 and other host cell receptors, has been a focus of this study. The present research goes beyond receptor recognition to explore Spike's influence on cellular metabolism. AP-MS interactome analysis revealed an interaction between the Spike S1 domain and lactate dehydrogenase B (LDHB), which was further confirmed by co-immunoprecipitation and immunofluorescence, indicating colocalisation in cells expressing the S1 domain. The study showed that Spike inhibits the catalytic activity of LDHB, leading to increased lactate levels in HEK-293T cells overexpressing the S1 subunit. In the hypothesised mechanism, Spike deprives LDHB of NAD+, facilitating a metabolic switch from aerobic to anaerobic energy production during infection. The Spike-NAD+ interacting region was characterised and mainly involves the W436 within the RDB domain. This novel hypothesis suggests that the Spike protein may play a broader role in altering host cell metabolism, thereby contributing to the pathophysiology of viral infection.

COVID-19 Vaccine mRNA Biodistribution: Maternal and Fetal Exposure Risks

SARS-CoV-2 infection during pregnancy has severe consequences on maternal and neonatal health. Presently, vaccination stands as a critical preventive measure for mitigating infection-related risks. Although the initial clinical trials for the COVID-19 vaccines excluded pregnant women, subsequent investigations have indicated mRNA vaccinations' effectiveness and short-term safety during pregnancy. However, there is a lack of information regarding the potential biodistribution of the vaccine mRNA during pregnancy and lactation. Recent findings indicate that COVID-19 vaccine mRNA has been detected in breast milk, suggesting that its presence is not confined to the injection site and raises the possibility of similar distribution to the placenta and the fetus. Furthermore, the potential effects and responses of the placenta and fetus to the vaccine mRNA are still unknown. While potential risks might exist with the exposure of the placenta and fetus to the COVID-19 mRNA vaccine, the application of mRNA therapies for maternal and fetal conditions offers a groundbreaking prospect. Future research should leverage the unique opportunity provided by the first-ever application of mRNA vaccines in humans to understand their biodistribution and impact on the placenta and fetus in pregnant women. Such insights could substantially advance the development of safer and more effective future mRNA-based therapies during pregnancy.

COVID-19 vaccine adverse events: Evaluating the pathophysiology with an emphasis on sulfur metabolism and endotheliopathy

In this narrative review, we assess the pathophysiology of severe adverse events that presented after vaccination with DNA and mRNA vaccines against COVID-19. The focus is on the perspective of an undersulfated and degraded glycocalyx, considering its impact on immunomodulation, inflammatory responses, coagulation and oxidative stress. The paper explores various factors that lead to glutathione and inorganic sulfate depletion and their subsequent effect on glycocalyx sulfation and other metabolites, including hormones. Components of COVID-19 vaccines, such as DNA and mRNA material, spike protein antigen and lipid nanoparticles, are involved in possible cytotoxic effects. The common thread connecting these adverse events is endotheliopathy or glycocalyx degradation, caused by depleted glutathione and inorganic sulfate levels, shear stress from circulating nanoparticles, aggregation and formation of protein coronas; leading to imbalanced immune responses and chronic release of pro-inflammatory cytokines, ultimately resulting in oxidative stress and systemic inflammatory response syndrome. By understanding the underlying pathophysiology of severe adverse events, better treatment options can be explored.

The Y498T499-SARS-CoV-2 spike (S) protein interacts poorly with rat ACE2 and does not affect the rat lung

The rat is a useful laboratory model for respiratory diseases. SARS-CoV-2 proteins, such as the spike (S) protein, can induce inflammation. This study has investigated the ability of the Q498Y, P499T (QP-YT) amino acid change, described in the S-protein of the mouse-adapted laboratory SARS-CoV-2 MA strain, to interact with rat angiotensin converting enzyme-2 (ACE2) and stimulate responses in rat lungs. A real-time S-ACE2 quantitative fusion assay shows that ancestral and L452R S-proteins fuse with human but not rat ACE2 expressed on HEK293 (human embryonic kidney-293) cells. The QP-YT S-protein retains the ability to fuse with human ACE2 and increases the binding to rat ACE2. Although lower lung of the rat contains both ACE2 and TMPRSS2 (transmembrane serine protease 2) target cells, intratracheal delivery of ancestral or QP-YT S-protein pseudotyped lentivirus did not induce measurable respiratory changes, inflammatory infiltration or innate mRNA responses. Isolation of primary cells from rat alveoli demonstrated the presence of cells expressing ACE2 and TMPRSS2. Infection of these cells, however, with ancestral or QP-YT S-protein pseudotyped lentivirus was not observed, and the QP-YT S-protein pseudotyped lentivirus poorly infected HEK293 cells expressing rat ACE2. Analysis of the amino acid changes across the S-ACE2 interface highlights not only the Y498 interaction with H353 as a likely facilitator of binding to rat ACE2 but also other amino acids that could improve this interaction. Thus, rat lungs contain cells expressing receptors for SARS-CoV-2, and the QP-YT S-protein variant can bind to rat ACE2, but this does not result in infection or stimulate responses in the lung. Further, amino acid changes in S-protein may enhance this interaction to improve the utility of the rat model for defining the role of the S-protein in driving lung inflammation.

MSC-extracellular vesicle microRNAs target host cell-entry receptors in COVID-19: in silico modeling for in vivo validation

BACKGROUND

Coronavirus disease 2019 (COVID-19) has created a global pandemic with significant morbidity and mortality. SARS-CoV-2 primarily infects the lungs and is associated with various organ complications. Therapeutic approaches to combat COVID-19, including convalescent plasma and vaccination, have been developed. However, the high mutation rate of SARS-CoV-2 and its ability to inhibit host T-cell activity pose challenges for effective treatment. Mesenchymal stem cells (MSCs) and their extracellular vesicles (MSCs-EVs) have shown promise in COVID-19 therapy because of their immunomodulatory and regenerative properties. MicroRNAs (miRNAs) play crucial regulatory roles in various biological processes and can be manipulated for therapeutic purposes.

OBJECTIVE

We aimed to investigate the role of lyophilized MSC-EVs and their microRNAs in targeting the receptors involved in SARS-CoV-2 entry into host cells as a strategy to limit infection. In silico microRNA prediction, structural predictions of the microRNA-mRNA duplex, and molecular docking with the Argonaut protein were performed.

METHODS

Male Syrian hamsters infected with SARS-CoV-2 were treated with human Wharton's jelly-derived Mesenchymal Stem cell-derived lyophilized exosomes (Bioluga Company)via intraperitoneal injection, and viral shedding was assessed. The potential therapeutic effects of MSCs-EVs were measured via histopathology of lung tissues and PCR for microRNAs.

RESULTS

The results revealed strong binding potential between miRNA‒mRNA duplexes and the AGO protein via molecular docking. MSCs-EVs reduced inflammation markers and normalized blood indices via the suppression of viral entry by regulating ACE2 and TMPRSS2 expression. MSCs-EVs alleviated histopathological aberrations. They improved lung histology and reduced collagen fiber deposition in infected lungs.

CONCLUSION

We demonstrated that MSCs-EVs are a potential therapeutic option for treating COVID-19 by preventing viral entry into host cells.

A novel multitargeted self-assembling peptide-siRNA complex for simultaneous inhibition of SARS-CoV-2-host cell interaction and replication

Effective therapeutics are necessary for managing severe COVID-19 disease despite the availability of vaccines. Small interfering RNA (siRNA) can silence viral genes and restrict SARS-CoV-2 replication. Cell-penetrating peptides is a robust method for siRNA delivery, enhancing siRNA stability and targeting specific receptors. We developed a peptide HE25 that blocks SARS-CoV-2 replication by various mechanisms, including the binding of multiple receptors involved in the virus's internalization, such as ACE2, integrins and NRP1. HE25 not only acts as a vehicle to deliver the SARS-CoV-2 RNA-dependent RNA polymerase siRNA into cells but also facilitates their internalization through endocytosis. Once inside endosomes, the siRNA is released into the cytoplasm through the Histidine-proton sponge effect and the selective cleavage of HE25 by cathepsin B. These mechanisms effectively inhibited the replication of the ancestral SARS-CoV-2 and the Omicron variant BA.5 in vitro. When HE25 was administered in vivo, either by intravenous injection or inhalation, it accumulated in lungs, veins and arteries, endothelium, or bronchial structure depending on the route. Furthermore, the siRNA/HE25 complex caused gene silencing in lung cells in vitro. The SARS-CoV-2 siRNA/HE25 complex is a promising therapeutic for COVID-19, and a similar strategy can be employed to combat future emerging viral diseases.

The Functions of SARS-CoV-2 Receptors in Diabetes-Related Severe COVID-19

Angiotensin-converting enzyme 2 (ACE2) is considered a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor of high importance, but due to its non-ubiquitous expression, studies of other proteins that may participate in virus internalisation have been undertaken. To date, many alternative receptors have been discovered. Their functioning may provide an explanation for some of the events observed in severe COVID-19 that cannot be directly explained by the model in which ACE2 constitutes the central point of infection. Diabetes mellitus type 2 (T2D) can induce severe COVID-19 development. Although many mechanisms associated with ACE2 can lead to increased SARS-CoV-2 virulence in diabetes, proteins such as basigin (CD147), glucose-regulated protein 78 kDa (GRP78), cluster of differentiation 4 (CD4), transferrin receptor (TfR), integrins α5β1/αvβ3, or ACE2 co-receptors neuropilin 2 (NRP2), vimentin, and even syalilated gangliosides may also be responsible for worsening the COVID-19 course. On the other hand, some others may play protective roles. Understanding how diabetes-associated mechanisms can induce severe COVID-19 via modification of virus receptor functioning needs further extensive studies.

Diminazene aceturate inhibits the SARS-CoV-2 spike protein-induced inflammation involving leukocyte migration and DNA extracellular traps formation

AIMS

To investigate the SARS-CoV-2 Spike protein (Spk)-induced inflammatory response and its downmodulation by diminazene aceturate (DIZE).

MATERIALS AND METHODS

Through inducing Spk inflammation in murine models, leukocyte migration to the peritoneum, levels of myeloperoxidase (MPO), malondialdehyde (MDA), rolling and adhesion of mesenteric leukocytes, and vascular permeability were investigated. Extracellular DNA traps (DETs) induced by Spk and the production of IL-6 and TNF-α were analyzed using human neutrophils, monocytes, and macrophages. In silico assays assessed the molecular interaction between DIZE and molecules related to leukocyte migration and DETs induction.

KEY FINDINGS

Spk triggered acute inflammation, demonstrated by increasing leukocyte migration. Oxidative stress was evidenced by elevated levels of MPO and MDA in the peritoneal liquid. DIZE attenuated cell migration, rolling, and leukocyte adhesion, improved vascular barrier function, mitigated DETs, and reduced the production of Spk-induced pro-inflammatory cytokines. Computational studies supported our findings, showing the molecular interaction of DIZE with targets such as β2 integrin, PI3K, and PAD2 due to its intermolecular coupling.

SIGNIFICANCE

Our results outline a novel role of DIZE as a potential therapeutic agent for mitigating Spk-induced inflammation.

COVID-19 in the Initiation and Progression of Atherosclerosis: Pathophysiology During and Beyond the Acute Phase

The incidence of atherosclerotic cardiovascular disease is increasing globally, especially in low- and middle-income countries, despite significant efforts to reduce traditional risk factors. Premature subclinical atherosclerosis has been documented in association with several viral infections. The magnitude of the recent COVID-19 pandemic has highlighted the need to understand the association between SARS-CoV-2 and atherosclerosis. This review examines various pathophysiological mechanisms, including endothelial dysfunction, platelet activation, and inflammatory and immune hyperactivation triggered by SARS-CoV-2 infection, with specific attention on their roles in initiating and promoting the progression of atherosclerotic lesions. Additionally, it addresses the various pathogenic mechanisms by which COVID-19 in the post-acute phase may contribute to the development of vascular disease. Understanding the overlap of these syndromes may enable novel therapeutic strategies. We further explore the need for guidelines for closer follow-up for the often-overlooked evidence of atherosclerotic cardiovascular disease among patients with recent COVID-19, particularly those with cardiometabolic risk factors.

The relationship between Nuclear Factor-Kappa B and Inhibitor-Kappa B parameters with clinical course in COVID-19 patients

BACKGROUND

We aimed to investigate the serum Nuclear Factor Kappa B (NF-κB) p105, NF-κB p65 and Inhibitor Kappa B Alpha (IκBα) levels in patients with mild/moderate Coronavirus Disease 2019 (COVID-19) and their association with the course of the disease.

MATERIALS AND METHODS

Blood was drawn from 35 COVID-19 patients who applied to the Department of Emergency Medicine of Istanbul University-Cerrahpasa at the time of diagnosis and from 35 healthy individuals. The patients were evaluated to have mild/moderate degree of disease according to National Early Warning Score 2 (NEWS2) scoring and computed tomography (CT) findings. The markers were studied in the obtained serum samples, using enzyme-linked immunoassay (ELISA). Receiver Operating Characteristic (ROC) analysis was performed. Statistical significance was evaluated to be p < 0.05.

RESULTS

NF-κB p105 levels were significantly higher in the COVID-19 group compared to the control group. C-reactive protein (CRP), D-dimer, ferritin levels of the patients were significantly higher (p < 0.001) compared to the control group, while the lymphocyte count was found lower (p = 0.001). IκBα and NF-κB p65 levels are similar in both groups. Threshold value for NF-κB p105 was above 0.78 ng/mL, sensitivity was 71.4% and specificity was 97.1% (p < 0.05). NF-κB p105 levels at the time of diagnosis of the patients who required supplemental oxygen (O2), were significantly higher (p < 0.01).

CONCLUSIONS

The rise in serum NF-κB p105 levels during the early stages of infection holds diagnostic value. Besides its relation with severity might have a prognostic feature to foresee the requirement for supplemental O2 that occurs during hospitalization.

Myocarditis associated with COVID-19 vaccination

Following the start of the COVID-19 vaccination campaign, the adverse events of myocarditis and pericarditis were linked mainly to mRNA COVID-19 vaccines by the regulatory authorities worldwide. COVID-19 vaccines have been administered to several million people and the risk of myocarditis post COVID-19 vaccination has been characterised in great detail. At the present time the research data available are scarce and there is still no clear understanding of the biological mechanism/s responsible for this disease. This manuscript provides a concise overview of the epidemiology of myocarditis and the most prominent mechanistic insights in the pathophysiology of the disease. Most importantly it underscores the needed next steps in the research agenda required to characterize the pathophysiology of this disease post-COVID-19 vaccination. Finally, it shares our perspectives and considerations for public health.

Genome-wide association study of BNT162b2 vaccine-related myocarditis identifies potential predisposing functional areas in Hong Kong adolescents

Vaccine-related myocarditis associated with the BNT162b2 vaccine is a rare complication, with a higher risk observed in male adolescents. However, the contribution of genetic factors to this condition remains uncertain. In this study, we conducted a comprehensive genetic association analysis in a cohort of 43 Hong Kong Chinese adolescents who were diagnosed with myocarditis shortly after receiving the BNT162b2 mRNA COVID-19 vaccine. A comparison of whole-genome sequencing data was performed between the confirmed myocarditis cases and a control group of 481 healthy individuals. To narrow down potential genomic regions of interest, we employed a novel clustering approach called ClusterAnalyzer, which prioritised 2,182 genomic regions overlapping with 1,499 genes for further investigation. Our pathway analysis revealed significant enrichment of these genes in functions related to cardiac conduction, ion channel activity, plasma membrane adhesion, and axonogenesis. These findings suggest a potential genetic predisposition in these specific functional areas that may contribute to the observed side effect of the vaccine. Nevertheless, further validation through larger-scale studies is imperative to confirm these findings. Given the increasing prominence of mRNA vaccines as a promising strategy for disease prevention and treatment, understanding the genetic factors associated with vaccine-related myocarditis assumes paramount importance. Our study provides valuable insights that significantly advance our understanding in this regard and serve as a valuable foundation for future research endeavours in this field.

Exploring Integrin α5β1 as a Potential Therapeutic Target for Pulmonary Arterial Hypertension: Insights from Comprehensive Multicenter Preclinical Studies

Pulmonary arterial hypertension (PAH) is characterized by obliterative vascular remodeling of the small pulmonary arteries (PA) and progressive increase in pulmonary vascular resistance (PVR) leading to right ventricular (RV) failure. Although several drugs are approved for the treatment of PAH, mortality remains high. Accumulating evidence supports a pathological function of integrins in vessel remodeling, which are gaining renewed interest as drug targets. However, their role in PAH remains largely unexplored. We found that the arginine-glycine-aspartate (RGD)-binding integrin α5β1 is upregulated in PA endothelial cells (PAEC) and PA smooth muscle cells (PASMC) from PAH patients and remodeled PAs from animal models. Blockade of the integrin α5β1 or depletion of the α5 subunit resulted in mitotic defects and inhibition of the pro-proliferative and apoptosis-resistant phenotype of PAH cells. Using a novel small molecule integrin inhibitor and neutralizing antibodies, we demonstrated that α5β1 integrin blockade attenuates pulmonary vascular remodeling and improves hemodynamics and RV function in multiple preclinical models. Our results provide converging evidence to consider α5β1 integrin inhibition as a promising therapy for pulmonary hypertension.

One sentence summary

The α5β1 integrin plays a crucial role in pulmonary vascular remodeling.

Tumour-derived Extracellular Vesicle and Particle Reprogramming of Interstitial Macrophages in the Lung Pre-Metastatic Niche Enhances Vascular Permeability and Metastatic Potential

Extracellular vesicles and particles (EVPs) are pivotal mediators of pre-metastatic niche formation and cancer progression, including induction of vascular permeability, which facilitates tumor cell extravasation and metastasis. However, the mechanisms through which EVPs exert this effect remain poorly understood. Here, we elucidate a novel mechanism by which tumor EVPs enhance endothelial cell permeability, tumor extravasation, and lung metastasis to different degrees, depending on tumor type. Strikingly, vascular leakiness is observed within 48h following tumor implantation and as early as one hour following intravenous injection of tumour-derived EVPs in naïve mice. Surprisingly, rather than acting directly on endothelial cells, EVPs first activate interstitial macrophages (IMs) leading to activation of JAK/STAT signaling and IL-6 secretion in IMs which subsequently promote endothelial permeability. Depletion of IMs significantly reduces tumour-derived EVP-dependent vascular leakiness and metastatic potential. Tumour EVPs that strongly induce vascular leakiness express high levels of ITGα5, and ITGα5 ablation impairs IM activation, cytokine secretion, and subsequently vascular permeability and metastasis. Importantly, IL-6 expression is elevated in IMs from non-involved tumor-adjacent lung tissue compared to distal lung tissue in lung cancer patients, highlight the clinical relevance of our discovery. Our findings identify a key role for IM activation as an initiating step in tumor type-specific EVP-driven vascular permeability and metastasis, offering promising targets for therapeutic intervention.

The Biodistribution of the Spike Protein after Ad26.COV2.S Vaccination Is Unlikely to Play a Role in Vaccine-Induced Immune Thrombotic Thrombocytopenia

Ad26.COV2.S vaccination can lead to vaccine-induced immune thrombotic thrombocytopenia (VITT), a rare but severe adverse effect, characterized by thrombocytopenia and thrombosis. The mechanism of VITT induction is unclear and likely multifactorial, potentially including the activation of platelets and endothelial cells mediated by the vaccine-encoded spike protein (S protein). Here, we investigated the biodistribution of the S protein after Ad26.COV2.S dosing in three animal models and in human serum samples. The S protein was transiently present in draining lymph nodes of rabbits after Ad26.COV2.S dosing. The S protein was detected in the serum in all species from 1 day to 21 days after vaccination with Ad26.COV2.S, but it was not detected in platelets, the endothelium lining the blood vessels, or other organs. The S protein S1 and S2 subunits were detected at different ratios and magnitudes after Ad26.COV2.S or COVID-19 mRNA vaccine immunization. However, the S1/S2 ratio did not depend on the Ad26 platform, but on mutation of the furin cleavage site, suggesting that the S1/S2 ratio is not VITT related. Overall, our data suggest that the S-protein biodistribution and kinetics after Ad26.COV2.S dosing are likely not main contributors to the development of VITT, but other S-protein-specific parameters require further investigation.

Functional diversification of innate and inflammatory immune responses mediated by antibody fragment crystallizable activities against SARS-CoV-2

Monoclonal antibodies (mAb) targeting the SARS-CoV-2 Spike (S) glycoprotein have been exploited for the treatment of severe COVID-19. In this study, we evaluated the immune-regulatory features of two neutralizing anti-S mAbs (nAbs), named J08 and F05, with wild-type (WT) conformation or silenced Fc functions. In the presence of D614G SARS-CoV-2, WT nAbs enhance intracellular viral uptake in immune cells and amplify antiviral type I Interferon and inflammatory cytokine and chemokine production without viral replication, promoting the differentiation of CD16+ inflammatory monocytes and innate/adaptive PD-L1+ and PD-L1+CD80+ plasmacytoid Dendritic Cells. In spite of a reduced neutralizing property, WT J08 nAb still promotes the IL-6 production and differentiation of CD16+ monocytes once binding Omicron BA.1 variant. Fc-mediated regulation of antiviral and inflammatory responses, in the absence of viral replication, highlighted in this study, might positively tune immune response during SARS-CoV-2 infection and be exploited also in mAb-based therapeutic and prophylactic strategies against viral infections.

Effects of Chronic Inflammatory Activation of Murine and Human Arterial Endothelial Cells at Normal Lipoprotein and Cholesterol Levels In Vivo and In Vitro

The activation of endothelial cells is crucial for immune defense mechanisms but also plays a role in the development of atherosclerosis. We have previously shown that inflammatory stimulation of endothelial cells on top of elevated lipoprotein/cholesterol levels accelerates atherogenesis. The aim of the current study was to investigate how chronic endothelial inflammation changes the aortic transcriptome of mice at normal lipoprotein levels and to compare this to the inflammatory response of isolated endothelial cells in vitro. We applied a mouse model expressing constitutive active IκB kinase 2 (caIKK2)-the key activator of the inflammatory NF-κB pathway-specifically in arterial endothelial cells and analyzed transcriptomic changes in whole aortas, followed by pathway and network analyses. We found an upregulation of cell death and mitochondrial beta-oxidation pathways with a predicted increase in endothelial apoptosis and necrosis and a simultaneous reduction in protein synthesis genes. The highest upregulated gene was ACE2, the SARS-CoV-2 receptor, which is also an important regulator of blood pressure. Analysis of isolated human arterial and venous endothelial cells supported these findings and also revealed a reduction in DNA replication, as well as repair mechanisms, in line with the notion that chronic inflammation contributes to endothelial dysfunction.

Histochemical Evidence for Reduced Immune Response in Nasal Mucosa of Patients with COVID-19

The primary entry point of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the nasal mucosa, where viral-induced inflammation occurs. When the immune response fails against SARS-CoV-2, understanding the altered response becomes crucial. This study aimed to compare SARS-CoV-2 immunological responses in the olfactory and respiratory mucosa by focusing on epithelia and nerves. Between 2020 and 2022, we obtained post mortem tissues from the olfactory cleft from 10 patients with histologically intact olfactory epithelia (OE) who died with or from COVID-19, along with four age-matched controls. These tissues were subjected to immunohistochemical reactions using antibodies against T cell antigens CD3, CD8, CD68, and SARS spike protein for viral evidence. Deceased patients with COVID-19 exhibited peripheral lymphopenia accompanied by a local decrease in CD3+ cells in the OE. However, SARS-CoV-2 spike protein was sparsely detectable in the OE. With regard to the involvement of nerve fibers, the present analysis suggested that SARS-CoV-2 did not significantly alter the immune response in olfactory or trigeminal fibers. On the other hand, SARS spike protein was detectable in both nerves. In summary, the post mortem investigation demonstrated a decreased T cell response in patients with COVID-19 and signs of SARS-CoV-2 presence in olfactory and trigeminal fibers.

Extracellular vesicles and endothelial dysfunction in infectious diseases

Cardiovascular diseases (CVDs) remain the leading cause of mortality and morbidity globally. Studies have shown that infections especially bacteraemia and sepsis are associated with increased risks for endothelial dysfunction and related CVDs including atherosclerosis. Extracellular vesicles (EVs) are small, sealed membrane-derived structures that are released into body fluids and blood from cells and/or microbes and are critically involved in a variety of important cell functions and disease development, including intercellular communications, immune responses and inflammation. It is known that EVs-mediated mechanism(s) is important in the development of endothelial dysfunction in infections with a diverse spectrum of microorganisms including Escherichia coli, Candida albicans, SARS-CoV-2 (the virus for COVID-19) and Helicobacter pylori. H. pylori infection is one of the most common infections globally. During H. pylori infection, EVs can carry H. pylori components, such as lipopolysaccharide, cytotoxin-associated gene A, or vacuolating cytotoxin A, and transfer these substances into endothelial cells, triggering inflammatory responses and endothelial dysfunction. This review is to illustrate the important role of EVs in the pathogenesis of infectious diseases, and the development of endothelial dysfunction in infectious diseases especially H. pylori infection, and to discuss the potential mechanisms and clinical implications.

SARS-CoV-2 spike protein receptor binding domain promotes IL-6 and IL-8 release via ATP/P2Y2 and ERK1/2 signaling pathways in human bronchial epithelia

The spike protein of SARS-CoV-2 as well as its receptor binding domain (RBD) has been demonstrated to be capable of activating the release of pro-inflammatory mediators in endothelial cells and immune cells such as monocytes. However, the effects of spike protein or its RBD on airway epithelial cells and mechanisms underlying these effects have not been adequately characterized. Here, we show that the RBD of spike protein alone can induce bronchial epithelial inflammation in a manner of ATP/P2Y2 dependence. Incubation of human bronchial epithelia with RBD induced IL-6 and IL-8 release, which could be inhibited by antibody. The incubation of RBD also up-regulated the expression of inflammatory indicators such as ho-1 and mkp-1. Furthermore, ATP secretion was observed after RBD treatment, P2Y2 receptor knock down by siRNA significantly suppressed the IL-6 and IL-8 release evoked by RBD. Additionally, S-RBD elevated the phosphorylation level of ERK1/2, and the effect that PD98059 can inhibit the pro-inflammatory cytokine release suggested the participation of ERK1/2. These novel findings provide new evidence of SARS-CoV-2 on airway inflammation and introduce purinergic signaling as promising treatment target.

Extracellular Vesicles: The Invisible Heroes and Villains of COVID-19 Central Neuropathology

Acknowledging the neurological symptoms of COVID-19 and the long-lasting neurological damage even after the epidemic ends are common, necessitating ongoing vigilance. Initial investigations suggest that extracellular vesicles (EVs), which assist in the evasion of the host's immune response and achieve immune evasion in SARS-CoV-2 systemic spreading, contribute to the virus's attack on the central nervous system (CNS). The pro-inflammatory, pro-coagulant, and immunomodulatory properties of EVs contents may directly drive neuroinflammation and cerebral thrombosis in COVID-19. Additionally, EVs have attracted attention as potential candidates for targeted therapy in COVID-19 due to their innate homing properties, low immunogenicity, and ability to cross the blood-brain barrier (BBB) freely. Mesenchymal stromal/stem cell (MSCs) secreted EVs are widely applied and evaluated in patients with COVID-19 for their therapeutic effect, considering the limited antiviral treatment. This review summarizes the involvement of EVs in COVID-19 neuropathology as carriers of SARS-CoV-2 or other pathogenic contents, as predictors of COVID-19 neuropathology by transporting brain-derived substances, and as therapeutic agents by delivering biotherapeutic substances or drugs. Understanding the diverse roles of EVs in the neuropathological aspects of COVID-19 provides a comprehensive framework for developing, treating, and preventing central neuropathology and the severe consequences associated with the disease.

SARS-CoV-2 induced vascular endothelial dysfunction: direct or indirect effects?

Clinical evidence reveals that manifestations of endothelial dysfunction are widely observed in COVID-19 and long-COVID patients. However, whether these detrimental effects are caused by direct infection of the endothelium or are indirectly mediated by systemic inflammation has been a matter of debate. It has been well acknowledged that endothelial cells (ECs) of the cardiovascular system ubiquitously express the SARS-CoV-2 entry receptor angiotensin-converting enzyme 2 (ACE2), yet accumulating evidence suggests that it is more predominantly expressed by pericytes and vascular smooth muscle cells of the mammalian blood vessel. Besides, replicative infection of ECs by SARS-CoV-2 has yet to be demonstrated both in vitro and in vivo. In this study, we review latest research on endothelial ACE2 expression in different vascular beds, and the heterogeneity in various EC subsets with differential ACE2 expression in response to SARS-CoV-2. We also discuss ACE2-independent alternative mechanisms underlying endothelial activation in COVID-19, and the clinical manifestations of SARS-CoV-2-induced endothelial dysfunction. Altogether, understanding ACE2-dependent and ACE2-independent mechanisms driving SARS-CoV-2-induced vascular dysfunction would shed light on strategies of more effective therapies targeting cardiovascular complications associated with COVID-19.

Self-DNA driven inflammation in COVID-19 and after mRNA-based vaccination: lessons for non-COVID-19 pathologies

The coronavirus disease 2019 (COVID-19) pandemic triggered an unprecedented concentration of economic and research efforts to generate knowledge at unequalled speed on deregulated interferon type I signalling and nuclear factor kappa light chain enhancer in B-cells (NF-κB)-driven interleukin (IL)-1β, IL-6, IL-18 secretion causing cytokine storms. The translation of the knowledge on how the resulting systemic inflammation can lead to life-threatening complications into novel treatments and vaccine technologies is underway. Nevertheless, previously existing knowledge on the role of cytoplasmatic or circulating self-DNA as a pro-inflammatory damage-associated molecular pattern (DAMP) was largely ignored. Pathologies reported 'de novo' for patients infected with Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)-2 to be outcomes of self-DNA-driven inflammation in fact had been linked earlier to self-DNA in different contexts, e.g., the infection with Human Immunodeficiency Virus (HIV)-1, sterile inflammation, and autoimmune diseases. I highlight particularly how synergies with other DAMPs can render immunogenic properties to normally non-immunogenic extracellular self-DNA, and I discuss the shared features of the gp41 unit of the HIV-1 envelope protein and the SARS-CoV 2 Spike protein that enable HIV-1 and SARS-CoV-2 to interact with cell or nuclear membranes, trigger syncytia formation, inflict damage to their host's DNA, and trigger inflammation - likely for their own benefit. These similarities motivate speculations that similar mechanisms to those driven by gp41 can explain how inflammatory self-DNA contributes to some of most frequent adverse events after vaccination with the BNT162b2 mRNA (Pfizer/BioNTech) or the mRNA-1273 (Moderna) vaccine, i.e., myocarditis, herpes zoster, rheumatoid arthritis, autoimmune nephritis or hepatitis, new-onset systemic lupus erythematosus, and flare-ups of psoriasis or lupus. The hope is to motivate a wider application of the lessons learned from the experiences with COVID-19 and the new mRNA vaccines to combat future non-COVID-19 diseases.

ACE2 improves endothelial cell function and reduces acute lung injury by downregulating FAK expression

Endothelial cell (EC) barrier dysfunction and increased adhesion of immune inflammatory cells to ECs crucially contribute to acute lung injury (ALI). Angiotensin-converting enzyme 2 (ACE2) is an essential regulator of the renin-angiotensin system (RAS) and exerts characteristic vasodilatory and anti-inflammatory effects. SARS-COV-2 infects the lungs by binding to ACE2, which can lead to dysregulation of ACE2 expression, further leading to ALI with predominantly vascular inflammation and eventually to more severe acute respiratory distress syndrome (ARDS). Therefore, restoration of ACE2 expression represents a valuable therapeutic approach for SARS-COV-2-related ALI/ARDS. In this study, we used polyinosinic-polycytidylic acid (Poly(I:C)), a double-stranded RNA analog, to construct a mouse ALI model that mimics virus infection. After Poly(I:C) exposure, ACE2 was downregulated in mouse lung tissues and in cultured ECs. Treatment with DIZE, an ACE2-activating compound, upregulated ACE2 expression and relieved ALI in mice. DIZE also improved barrier function and reduced the number of THP-1 monocytes adhering to cultured ECs. Focal adhesion kinase (FAK) and phosphorylated FAK (p-FAK) levels were increased in lung tissues of ALI mice as well as in Poly(I:C)-treated ECs in vitro. Both DIZE and the FAK inhibitor PF562271 decreased FAK/p-FAK expression in both ALI models, attenuating ALI severity in vivo and increasing barrier function and reducing monocyte adhesion in cultured ECs. Furthermore, in vivo experiments using ANG 1-7 and the MAS inhibitor A779 corroborated that DIZE-mediated ACE2 activation stimulated the activity of the ANG 1-7/MAS axis, which inhibited FAK/p-FAK expression in the mouse lung. These findings provide further evidence that activation of ACE2 in ECs may be a valuable therapeutic strategy for ALI.

Fatal Myocarditis following COVID-19 mRNA Immunization: A Case Report and Differential Diagnosis Review

Carditis in childhood is a rare disease with several etiologies. We report a case of infant death due to pericarditis and myocarditis after the mRNA vaccine against COVID-19 (COVIDmRNAV). A 7-year-old male child received the first dose of the COVIDmRNAV and presented with monoarthritis and a fever non-responsive to oral antibiotics. The laboratory investigation showed signs of infection (leukocytosis, high levels of c-reactive protein). His condition rapidly deteriorated, and the patient died. The autopsy identified pericardial fibrin deposits, hemorrhagic areas in the myocardium, and normal valves. A diffuse intermyocardial inflammatory infiltrate composed of T CD8+ lymphocytes and histiocytes was identified. An antistreptolysin O (ASO) dosage showed high titers. The presence of arthritis, elevated ASO, and carditis fulfills the criteria for rheumatic fever. However, valve disease and Aschoff's nodules, present in 90% of rheumatic carditis cases, were absent in this case. The temporal correlation with mRNA vaccination prompted its inclusion as one of the etiologies. In cases of myocardial damage related to COVID-19mRNAV, it appears to be related to the expression of exosomes and lipid nanoparticles, leading to a cytokine storm. The potential effects of the COVID-19mRNAV must be considered in the pathogenesis of this disease, whether as an etiology or a contributing factor to a previously initiated myocardial injury.

Multifaceted role of SARS-CoV-2 structural proteins in lung injury

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the third human coronavirus to cause acute respiratory distress syndrome (ARDS) and contains four structural proteins: spike, envelope, membrane, and nucleocapsid. An increasing number of studies have demonstrated that all four structural proteins of SARS-CoV-2 are capable of causing lung injury, even without the presence of intact virus. Therefore, the topic of SARS-CoV-2 structural protein-evoked lung injury warrants more attention. In the current article, we first synopsize the structural features of SARS-CoV-2 structural proteins. Second, we discuss the mechanisms for structural protein-induced inflammatory responses in vitro. Finally, we list the findings that indicate structural proteins themselves are toxic and sufficient to induce lung injury in vivo. Recognizing mechanisms of lung injury triggered by SARS-CoV-2 structural proteins may facilitate the development of targeted modalities in treating COVID-19.

Antifibrotic Drugs against Idiopathic Pulmonary Fibrosis and Pulmonary Fibrosis Induced by COVID-19: Therapeutic Approaches and Potential Diagnostic Biomarkers

The COVID-19 pandemic has had a significant impact on the health and economy of the global population. Even after recovery from the disease, post-COVID-19 symptoms, such as pulmonary fibrosis, continue to be a concern. This narrative review aims to address pulmonary fibrosis (PF) from various perspectives, including the fibrotic mechanisms involved in idiopathic and COVID-19-induced pulmonary fibrosis. On the other hand, we also discuss the current therapeutic drugs in use, as well as those undergoing clinical or preclinical evaluation. Additionally, this article will address various biomarkers with usefulness for PF prediction, diagnosis, treatment, prognosis, and severity assessment in order to provide better treatment strategies for patients with this disease.

Integrin αvβ1 facilitates ACE2-mediated entry of SARS-CoV-2

Integrins have been suggested to be involved in SARS-CoV-2 infection, but the underlying mechanisms remain largely unclear. This study aimed to investigate how integrins facilitate the ACE2-mediated cellular entry of SARS-CoV-2. We first tested the susceptibility of a panel of human cell lines to SARS-CoV-2 infection using the spike protein pseudotyped virus assay and examined the expression levels of integrins in these cell lines by qPCR, western blot and flow cytometry. We found that integrin αvβ1 was highly enriched in the SARS-CoV-2 susceptible cell lines. Additional studies demonstrated that RGD (403-405)→AAA mutant was defective in binding to integrin αvβ1 compared to its wild type counterpart, and anti-αvβ1 integrin antibodies significantly inhibited the entry of SARS-CoV-2 into the cells. Further studies using mouse NIH3T3 cells expressing human ACE2, integrin αv, integrin β1, and/or integrin αvβ1 suggest that integrin αvβ1 was unable to function as an independent receptor but could significantly facilitate the cellular entry of SASR-CoV-2. Finally, we observed that the Omicron exhibited a significant increase in the ACE2-mediated viral entry. Our findings may enhance our understanding of the pathogenesis of SARS-CoV-2 infection and offer potential therapeutic target for COVID-19.

Epidemiology, Symptoms and Pathophysiology of Long Covid Complications

Long COVID, or post-acute sequelae of SARS-CoV-2 infection, reports to affect a significant proportion of COVID-19 survivors, leading to persistent and multi-organ complications. This review examines the epidemiology, symptoms of long COVID complications, including cardiac, hematological, vascular, pulmonary, neuropsychiatric, renal, gastrointestinal, musculoskeletal, immune dysregulation, and dermatological issues. By synthesizing the latest research, this article provides a comprehensive overview of the prevalence and detailed pathophysiological mechanisms underlying these complications. The purpose of this review is to enhance the understanding of diverse and complex nature of long COVID and emphasize the need for ongoing research, seeking to support future studies for better management of long COVID.

SARS-CoV-2 and the spike protein in endotheliopathy

SARS-CoV-2, the causative agent of COVID-19, primarily affects the epithelial compartment in the upper and lower airways. There is evidence that the microvasculature in both the pulmonary and extrapulmonary systems is a major target of SARS-CoV-2. Consistent with this, vascular dysfunction and thrombosis are the most severe complications in COVID-19. The proinflammatory milieu triggered by the hyperactivation of the immune system by SARS-CoV-2 has been suggested to be the main trigger for endothelial dysfunction during COVID-19. More recently, a rapidly growing number of reports have indicated that SARS-CoV-2 can interact directly with endothelial cells through the spike protein, leading to multiple instances of endothelial dysfunction. Here, we describe all the available findings showing the direct effect of the SARS-CoV-2 spike protein on endothelial cells and offer mechanistic insights into the molecular basis of vascular dysfunction in severe COVID-19.

Inhibitory effects of SARS-CoV-2 spike protein and BNT162b2 vaccine on erythropoietin-induced globin gene expression in erythroid precursor cells from patients with β-thalassemia

During the recent coronavirus disease 2019 (COVID-19) pandemic several patients with β-thalassemia have been infected by severe acute respiratory syndrome coronavirus (SARS-CoV-2), and most patients were vaccinated against SARS-CoV-2. Recent studies demonstrate an impact of SARS-CoV-2 infection on the hematopoietic system. The main objective of this study was to verify the effects of exposure of erythroid precursor cells (ErPCs) from patients with β-thalassemia to SARS-CoV-2 spike protein (S-protein) and the BNT162b2 vaccine. Erythropoietin (EPO)-cultured ErPCs have been either untreated or treated with S-protein or BNT162b2 vaccine. The employed ErPCs were from a β-thalassemia cellular Biobank developed before the COVID-19 pandemic. The genotypes were β+-IVSI-110/β+-IVSI-110 (one patient),  β039/β+-IVSI-110 (3 patients), and β039/ β039 (2 patients). After treatment with S-protein or BNT162b2 for 5 days, lysates were analyzed by high performance liquid chromatography (HPLC), for hemoglobin production, and isolated RNA was assayed by RT-qPCR, for detection of globin gene expression. The main conclusions of the results obtained are that SARS-CoV-2 S-protein and BNT162b2 vaccine (a) inhibit fetal hemoglobin (HbF) production by β-thalassemic ErPCs and (b) inhibit γ-globin mRNA accumulation. In addition, we have performed in silico studies suggesting a high affinity of S-protein to HbF. Remarkably, the binding interaction energy of fetal hemoglobin to S-protein was comparable with that of angiotensin-converting enzyme 2 (ACE2). Our results are consistent with the hypothesis of a relevant impact of SARS-CoV-2 infection and COVID-19 vaccination on the hematopoietic system.

The Functional Roles of MDSCs in Severe COVID-19 Pathogenesis

Severe COVID-19 is a major cause of morbidity and mortality worldwide, especially among those with co-morbidities, the elderly, and the immunocompromised. However, the molecular determinants critical for severe COVID-19 progression remain to be fully elucidated. Meta-analyses of transcriptomic RNAseq and single-cell sequencing datasets comparing severe and mild COVID-19 patients have demonstrated that the early expansion of myeloid-derived suppressor cells (MDSCs) could be a key feature of severe COVID-19 progression. Besides serving as potential early prognostic biomarkers for severe COVID-19 progression, several studies have also indicated the functional roles of MDSCs in severe COVID-19 pathogenesis and possibly even long COVID. Given the potential links between MDSCs and severe COVID-19, we examine the existing literature summarizing the characteristics of MDSCs, provide evidence of MDSCs in facilitating severe COVID-19 pathogenesis, and discuss the potential therapeutic avenues that can be explored to reduce the risk and burden of severe COVID-19. We also provide a web app where users can visualize the temporal changes in specific genes or MDSC-related gene sets during severe COVID-19 progression and disease resolution, based on our previous study.

Vasoinhibin's Apoptotic, Inflammatory, and Fibrinolytic Actions Are in a Motif Different From Its Antiangiogenic HGR Motif

Vasoinhibin, a proteolytic fragment of the hormone prolactin, inhibits blood vessel growth (angiogenesis) and permeability, stimulates the apoptosis and inflammation of endothelial cells, and promotes fibrinolysis. The antiangiogenic and antivasopermeability properties of vasoinhibin were recently traced to the HGR motif located in residues 46 to 48 (H46-G47-R48), allowing the development of potent, orally active, HGR-containing vasoinhibin analogues for therapeutic use against angiogenesis-dependent diseases. However, whether the HGR motif is also responsible for the apoptotic, inflammatory, and fibrinolytic properties of vasoinhibin has not been addressed. Here, we report that HGR-containing analogues are devoid of these properties. Instead, the incubation of human umbilical vein endothelial cells with oligopeptides containing the sequence HNLSSEM, corresponding to residues 30 to 36 of vasoinhibin, induced apoptosis, nuclear translocation of NF-κB, expression of genes encoding leukocyte adhesion molecules (VCAM1 and ICAM1) and proinflammatory cytokines (IL1B, IL6, and TNF), and adhesion of peripheral blood leukocytes. Also, intravenous or intra-articular injection of HNLSSEM-containing oligopeptides induced the expression of Vcam1, Icam1, Il1b, Il6, and Tnf in the lung, liver, kidney, eye, and joints of mice and, like vasoinhibin, these oligopeptides promoted the lysis of plasma fibrin clots by binding to plasminogen activator inhibitor-1 (PAI-1). Moreover, the inhibition of PAI-1, urokinase plasminogen activator receptor, or NF-κB prevented the apoptotic and inflammatory actions. In conclusion, the functional properties of vasoinhibin are segregated into 2 different structural determinants. Because apoptotic, inflammatory, and fibrinolytic actions may be undesirable for antiangiogenic therapy, HGR-containing vasoinhibin analogues stand as selective and safe agents for targeting pathological angiogenesis.

The anti-SARS-CoV-2 BNT162b2 vaccine suppresses mithramycin-induced erythroid differentiation and expression of embryo-fetal globin genes in human erythroleukemia K562 cells

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causative of the ongoing coronavirus disease 2019 (COVID-19) pandemic. The SARS-CoV-2 Spike protein (S-protein) plays an important role in the early phase of SARS-CoV-2 infection through efficient interaction with ACE2. The S-protein is produced by RNA-based COVID-19 vaccines, that were fundamental for the reduction of the viral spread within the population and the clinical severity of COVID-19. However, the S-protein has been hypothesized to be responsible for damaging cells of several tissues and for some important side effects of RNA-based COVID-19 vaccines. Considering the impact of COVID-19 and SARS-CoV-2 infection on the hematopoietic system, the aim of this study was to verify the effect of the BNT162b2 vaccine on erythroid differentiation of the human K562 cell line, that has been in the past intensively studied as a model system mimicking some steps of erythropoiesis. In this context, we focused on hemoglobin production and induced expression of embryo-fetal globin genes, that are among the most important features of K562 erythroid differentiation. We found that the BNT162b2 vaccine suppresses mithramycin-induced erythroid differentiation of K562 cells. Reverse-transcription-qPCR and Western blotting assays demonstrated that suppression of erythroid differentiation was associated with sharp inhibition of the expression of α-globin and γ-globin mRNA accumulation. Inhibition of accumulation of ζ-globin and ε-globin mRNAs was also observed. In addition, we provide in silico studies suggesting a direct interaction between SARS-CoV-2 Spike protein and Hb Portland, that is the major hemoglobin produced by K562 cells. This study thus provides information suggesting the need of great attention on possible alteration of hematopoietic parameters following SARS-CoV-2 infection and/or COVID-19 vaccination.