SARS-CoV-2 Spike protein enhances ACE2 expression via facilitating Interferon effects in bronchial epithelium

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.

TMPRSS2 expression in oral mucosal cells induced by transfected double-stranded RNA and IL-1β

OBJECTIVES

Transmembrane serine protease 2 (TMPRSS2) plays a key role in the entry of viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A into host cells, and its elevated expression is a risk factor for the spread of viral infection. However, TMPRSS2 expression and the factors related to its induction in oral keratinocytes and fibroblasts remain largely unknown. Here, we examined TMPRSS2 expression and factors related to its induction in oral mucosal cells.

METHODS

TMPRSS2 expression was examined in oral keratinocytes (RT7) and fibroblasts (GT1). Subsequently, TMPRSS2 induction in was analyzed in both cell types following transfection of nucleic acid and inflammatory cytokines, such as interleukin (IL)-1β. Finally, the effects of IL-1β on STAT1 activation related to double-stranded RNA (dsRNA)-induced TMPRSS2 expression were examined.

RESULTS

RT7 and GT1 cells exhibited constitutive TMPRSS2 mRNA and protein expression. Transfection with Poly(I:C) (as a dsRNA) and poly (dA:dT) (as a double-stranded DNA [dsDNA]) increased TMPRSS2 expression. TMPRSS2 expression was also increased by IL-1β, but not IFN-γ or TNF-α, while the combination of IL-1β and transfected Poly(I:C) caused a dramatic increase in TMPRSS2 expression as compared to each alone in both cell types. IL-1β also enhanced transfected Poly(I:C)-activated STAT1 related to TMPRSS2 expression.

CONCLUSIONS

TMPRSS2-expressing oral keratinocytes and fibroblasts are targets of SARS-CoV-2 and influenza A virus. TMPRSS2 expression, in cooperation with IL-1β, plays an important role in promoting infection during virus invasion in oral mucosal cells.

Thymidine phosphorylase mediates SARS-CoV-2 spike protein enhanced thrombosis in K18-hACE2TG mice

INTRODUCTION

Thymidine phosphorylase (TYMP), which facilitates platelet activation and thrombosis, is significantly increased in COVID-19 patients. We hypothesize that TYMP mediates SARS-CoV-2 spike protein (SP)-induced thrombosis.

MATERIALS AND METHODS

Plasmids encoding wildtype SP or empty vector (p3.1) were transfected into COS-7 cells, and cell lysates were prepared as a reservoir for SP or p3.1 (control), respectively. K18-hACE2TG and K18-hACE2TG/Tymp-/- mice were treated with a single dose of SP or p3.1 by intraperitoneal injection and then subjected to thrombosis studies three days later. The role of SP on inflammatory signaling activation was assessed in BEAS-2B cells.

RESULTS

SARS-CoV-2 SP increased the expression of TYMP, resulting in the activation of STAT3 and NF-κB in BEAS-2B cells. A siRNA-mediated knockdown of TYMP attenuated SP-enhanced activation of STAT3. SP significantly promoted arterial thrombosis in K18-hACE2TG mice. SP-accelerated thrombosis was attenuated by inhibition or genetic ablation of TYMP. SP treatment did not influence ADP- or collagen-induced platelet aggregation but significantly increased platelet adhesion to fibrinogen. SP treatment also significantly shortened activated partial thromboplastin time, which was reversed and even prolonged by TYMP deficiency. Additionally, SP binds to platelet factor 4 (PF4) and TYMP. TYMP does not bind PF4 but enhances the formation of the SP/PF4 complex, which may augment the procoagulant and prothrombotic effect of PF4.

CONCLUSIONS

We conclude that SP is prothrombotic and upregulates TYMP expression, and TYMP inhibition or knockout mitigates SP-enhanced thrombosis. These findings suggest that inhibition of TYMP may be a novel therapeutic strategy for COVID-19-associated thrombosis.

Fullerenol C60(OH)40 Nanoparticles and Ectoine Protect Human Nasal Epithelial Cells Against the Cytokine Storm After Addition of the Full-Length Spike Protein from SARS-CoV-2

INTRODUCTION AND OBJECTIVE

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters the nasal cavity, penetrates the nasal epithelial cells through the interaction of its spike protein with the host cell receptor angiotensin-converting enzyme 2 (ACE2) and then triggers a cytokine storm. We aimed to assess the biocompatibility of fullerenol nanoparticles C60(OH)40 and ectoine, and to document their effect on the protection of primary human nasal epithelial cells (HNEpCs) against the effects of interaction with the fragment of virus - spike protein. This preliminary research is the first step towards the construction of a intranasal medical device with a protective, mechanical function against SARS-CoV-2 similar to that of personal protective equipment (eg masks).

METHODS

We used HNEpCs and the full-length spike protein from SARS-CoV-2 to mimic the first stage of virus infection. We assessed cell viability with the XTT assay and a spectrophotometer. May-Grünwald Giemsa and periodic acid-Schiff staining served to evaluate HNEpC morphology. We assessed reactive oxygen species (ROS) production by using 2',7'-dichlorofluorescin diacetate and commercial kit. Finally, we employed reverse transcription polymerase chain reaction, Western blotting and confocal microscopy to determine the expression of angiotensin-converting enzyme 2 (ACE2) and inflammatory cytokines.

RESULTS

There was normal morphology and unchanged viability of HNEpCs after incubation with 10 mg/L C60(OH)40, 0.2% ectoine or their composite for 24 h. The spike protein exerted cytotoxicity via ROS production. Preincubation with the composite protected HNEpCs against the interaction between the spike protein and the host membrane and prevented the production of key cytokines characteristic of severe coronavirus disease 2019, including interleukin 6 and 8, monocyte chemotactic protein 1 and 2, tissue inhibitor of metalloproteinases 2 and macrophage colony-stimulating factor.

CONCLUSION

In the future, the combination of fullerenol and ectoine may be used to prevent viral infections as an intranasal medical device for people with reduced immunity and damaged mucous membrane.

Extracellular ISG15 triggers ISGylation via a type-I interferon independent non-canonical mechanism to regulate host response during virus infection

Type-I interferons (IFN) induce cellular proteins with antiviral activity. One such protein is Interferon Stimulated Gene 15 (ISG15). ISG15 is conjugated to proteins during ISGylation to confer antiviral activity and regulate cellular activities associated with inflammatory and neurodegenerative diseases and cancer. Apart from ISGylation, unconjugated free ISG15 is also released from cells during various conditions, including virus infection. The role of extracellular ISG15 during virus infection was unknown. We show that extracellular ISG15 triggers ISGylation and acts as a soluble antiviral factor to restrict virus infection via an IFN-independent mechanism. Specifically, extracellular ISG15 acts post-translationally to markedly enhance the stability of basal intracellular ISG15 protein levels to support ISGylation. Furthermore, extracellular ISG15 interacts with cell surface integrin (α5β1 integrins) molecules via its RGD-like motif to activate the integrin-FAK (Focal Adhesion Kinase) pathway resulting in IFN-independent ISGylation. Thus, our studies have identified extracellular ISG15 protein as a new soluble antiviral factor that confers IFN-independent non-canonical ISGylation via the integrin-FAK pathway by post-translational stabilization of intracellular ISG15 protein.

Transcriptional regulation of SARS-CoV-2 receptor ACE2 by SP1

Angiotensin-converting enzyme 2 (ACE2) is a major cell entry receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The induction of ACE2 expression may serve as a strategy by SARS-CoV-2 to facilitate its propagation. However, the regulatory mechanisms of ACE2 expression after viral infection remain largely unknown. Using 45 different luciferase reporters, the transcription factors SP1 and HNF4α were found to positively and negatively regulate ACE2 expression, respectively, at the transcriptional level in human lung epithelial cells (HPAEpiCs). SARS-CoV-2 infection increased the transcriptional activity of SP1 while inhibiting that of HNF4α. The PI3K/AKT signaling pathway, activated by SARS-CoV-2 infection, served as a crucial regulatory node, inducing ACE2 expression by enhancing SP1 phosphorylation-a marker of its activity-and reducing the nuclear localization of HNF4α. However, colchicine treatment inhibited the PI3K/AKT signaling pathway, thereby suppressing ACE2 expression. In Syrian hamsters (Mesocricetus auratus) infected with SARS-CoV-2, inhibition of SP1 by either mithramycin A or colchicine resulted in reduced viral replication and tissue injury. In summary, our study uncovers a novel function of SP1 in the regulation of ACE2 expression and identifies SP1 as a potential target to reduce SARS-CoV-2 infection.

The basis of complications in the context of SARS-CoV-2 infection: Pathological activation of ADAM17

The virulence of SARS-CoV-2 decreases with increasing infectivity, the primary approaches for antiviral treatments will be preventing or minimizing the complications resulting from virus infection. ADAM metallopeptidase domain 17 (ADAM17) activation by SARS-CoV-2 infection has a dual effect on the development of the disease: increased release of inflammatory cytokines and dysregulation of Angiotensin converting enzyme II (ACE2) on cell surfaces, inflammatory cytokine infiltration and loss of ACE2 protective function lead to a significant increase in the incidence of related complications. Importantly, pathologically activated ADAM17 showed superior features than S protein in regulating ACE2 expression and participating in the intra cellular replication of SARS-CoV-2. In short, SARS-CoV-2 elicits only a limited immune response when it promotes its own replication and pathogenicity through ADAM17. Therefore, the pathological activation of ADAM17 may also represent a diminished innate antiviral defense and an altered strategy of SARS-CoV-2 infection. In this review, we summarized recent advances in our understanding of the pathophysiology of ADAM17, with a focus on the new findings that SARS-CoV-2 affects ADAM17 expression through Furin protein converting enzyme and Mitogen-activated protein kinase (MAPK) pathway, and raises the hypothesis that SARS-CoV-2 may mediates the pathological activation of ADAM17 by hijacking the actin regulatory pathway, and discussed the underlying biological principles.

Hypercapnia increases ACE2 expression and pseudo-SARS-CoV-2 entry in bronchial epithelial cells by augmenting cellular cholesterol

Patients with chronic lung disease, obesity, and other co-morbid conditions are at increased risk of severe illness and death when infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Hypercapnia, the elevation of CO2 in blood and tissue, commonly occurs in patients with severe acute and chronic lung disease, including those with pulmonary infections, and is also associated with high mortality risk. We previously reported that hypercapnia increases viral replication and mortality of influenza A virus infection in mice. We have also shown that culture in elevated CO2 upregulates expression of cholesterol synthesis genes in primary human bronchial epithelial cells. Interestingly, factors that increase the cholesterol content of lipid rafts and lipid droplets, platforms for viral entry and assembly, enhance SARS-CoV-2 infection. In the current study, we investigated the effects of hypercapnia on ACE2 expression and entry of SARS-CoV-2 pseudovirus (p-SARS-CoV-2) into airway epithelial cells. We found that hypercapnia increased ACE2 expression and p-SARS-CoV-2 uptake by airway epithelium in mice, and in cultured VERO and human bronchial epithelial cells. Hypercapnia also increased total cellular and lipid raft-associated cholesterol in epithelial cells. Moreover, reducing cholesterol synthesis with inhibitors of sterol regulatory element binding protein 2 (SREBP2) or statins, and depletion of cellular cholesterol, each blocked the hypercapnia-induced increases in ACE2 expression and p-SARS-CoV-2 entry into epithelial cells. Cigarette smoke extract (CSE) also increased ACE2 expression, p-SARS-CoV-2 entry and cholesterol accumulation in epithelial cells, an effect not additive to that of hypercapnia, but also inhibited by statins. These findings reveal a mechanism that may account, in part, for poor clinical outcomes of SARS-CoV-2 infection in patients with advanced lung disease and hypercapnia, and in those who smoke cigarettes. Further, our results suggest the possibility that cholesterol-lowering therapies may be of particular benefit in patients with hypercapnia when exposed to or infected with SARS-CoV-2.

Spatiotemporally organized immunomodulatory response to SARS-CoV-2 virus in primary human broncho-alveolar epithelia

The COVID-19 pandemic continues to be a health crisis with major unmet medical needs. The early responses from airway epithelial cells, the first target of the virus regulating the progression toward severe disease, are not fully understood. Primary human air-liquid interface cultures representing the broncho-alveolar epithelia were used to study the kinetics and dynamics of SARS-CoV-2 variants infection. The infection measured by nucleoprotein expression, was a late event appearing between day 4-6 post infection for Wuhan-like virus. Other variants demonstrated increasingly accelerated timelines of infection. All variants triggered similar transcriptional signatures, an "early" inflammatory/immune signature preceding a "late" type I/III IFN, but differences in the quality and kinetics were found, consistent with the timing of nucleoprotein expression. Response to virus was spatially organized: CSF3 expression in basal cells and CCL20 in apical cells. Thus, SARS-CoV-2 virus triggers specific responses modulated over time to engage different arms of immune response.

Inhibiting the Deubiquitinase UCHL1 Reduces SARS-CoV-2 Viral Uptake by ACE2

Coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a significant public health burden with limited treatment options. Many β-coronaviruses, including SARS-CoV-2, gain entry to host cells through the interaction of SARS-CoV-2 spike protein with membrane-bound ACE2 (angiotensin-converting enzyme 2). Given its necessity for SARS-CoV-2 infection, ACE2 represents a potential therapeutic target in COVID-19. However, early attempts focusing on ACE2 in COVID-19 have not validated it as a druggable target nor identified other ACE2-related novel proteins for therapeutic intervention. Here, we identify a mechanism for ACE2 protein modulation by the deubiquitinase (DUB) enzyme UCHL1 (ubiquitin carboxyl-terminal hydrolase isozyme L1). ACE2 is constitutively ubiquitinated and degraded by the proteasome in lung epithelia. SARS-CoV-2 spike protein cellular internalization increased ACE2 protein abundance by decreasing its degradation. Using an siRNA library targeting 96 human DUBs, we identified UCHL1 as a putative regulator of ACE2 function as a viral receptor. Overexpressed UCHL1 preserved ACE2 protein abundance, whereas silencing of the DUB in cells destabilized ACE2 through increased polyubiquitination. A commercially available small molecule inhibitor of UCHL1 DUB activity decreased ACE2 protein concentrations coupled with inhibition of SARS-CoV-2 infection in epithelial cells. These findings describe a unique pathway of ACE2 regulation uncovering UCHL1 as a potential therapeutic target to modulate COVID-19 viral entry as a platform for future small molecule design and testing.

Spatiotemporally organized immunomodulatory response to SARS-CoV-2 virus in primary human broncho-alveolar epithelia

The COVID-19 pandemic continues to be a health crisis with major unmet medical needs. The early responses from airway epithelial cells, the first target of the virus regulating the progression towards severe disease, are not fully understood. Primary human air-liquid interface cultures representing the broncho-alveolar epithelia were used to study the kinetics and dynamics of SARS-CoV-2 variants infection. The infection measured by nucleoprotein expression, was a late event appearing between day 4-6 post infection for Wuhan-like virus. Other variants demonstrated increasingly accelerated timelines of infection. All variants triggered similar transcriptional signatures, an "early" inflammatory/immune signature preceding a "late" type I/III IFN, but differences in the quality and kinetics were found, consistent with the timing of nucleoprotein expression. Response to virus was spatially organized: CSF3 expression in basal cells and CCL20 in apical cells. Thus, SARS-CoV-2 virus triggers specific responses modulated over time to engage different arms of immune response.

JAK-STAT activation contributes to cytotoxic T cell-mediated basal cell death in human chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) is the leading cause of death in lung transplant recipients. CLAD is characterized clinically by a persistent decline in pulmonary function and histologically by the development of airway-centered fibrosis known as bronchiolitis obliterans. There are no approved therapies to treat CLAD, and the mechanisms underlying its development remain poorly understood. We performed single-cell RNA-Seq and spatial transcriptomic analysis of explanted tissues from human lung recipients with CLAD, and we performed independent validation studies to identify an important role of Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling in airway epithelial cells that contributes to airway-specific alloimmune injury. Specifically, we established that activation of JAK-STAT signaling leads to upregulation of major histocompatibility complex 1 (MHC-I) in airway basal cells, an important airway epithelial progenitor population, which leads to cytotoxic T cell-mediated basal cell death. This study provides mechanistic insight into the cell-to-cell interactions driving airway-centric alloimmune injury in CLAD, suggesting a potentially novel therapeutic strategy for CLAD prevention or treatment.

Based on network pharmacology and bioinformatics to analyze the mechanism of action of Astragalus membranaceus in the treatment of vitiligo and COVID-19

Coronavirus disease 2019 (COVID-19) is spreading rapidly around the world. However, the treatment of vitiligo combined with COVID-19 has not been reported. Astragalus membranaceus (AM) has a therapeutic effect on patients with vitiligo and COVID-19. This study aims to discover its possible therapeutic mechanisms and provide potential drug targets. Using the Chinese Medicine System Pharmacological Database (TCMSP), GEO database and Genecards websites and other databases, AM target, vitiligo disease target, and COVID-19 related gene set were established. Then find the crossover genes by taking the intersection. Then use GO, KEGG enrichment analysis, and PPI network to discover its underlying mechanism. Finally, by importing drugs, active ingredients, crossover genes, and enriched signal pathways into Cytoscape software, a "drug-active ingredient-target signal pathway-" network is constructed. TCMSP screened and obtained 33 active ingredients including baicalein (MOL002714), NEOBAICALEIN (MOL002934), Skullcapflavone II (MOL002927), and wogonin (MOL000173), which acted on 448 potential targets. 1166 differentially expressed genes for vitiligo were screened by GEO. CIVID-19 related genes were screened by Genecards. Then by taking the intersection, a total of 10 crossover genes (PTGS2, CDK1, STAT1, BCL2L1, SCARB1, HIF1A, NAE1, PLA2G4A, HSP90AA1, and HSP90B1) were obtained. KEGG analysis found that it was mainly enriched in signaling pathways such as IL-17 signaling pathway, Th17 cell differentiation, Necroptosis, NOD-like receptor signaling pathway. Five core targets (PTGS2, STAT1, BCL2L1, HIF1A, and HSP90AA1) were obtained by analyzing the PPI network. The network of "active ingredients-crossover genes" was constructed by Cytoscape, and the 5 main active ingredients acting on the 5 core crossover genes acacetin, wogonin, baicalein, bis2S)-2-ethylhexyl) benzene-1,2-dicarboxylate and 5,2'-Dihydroxy-6,7,8-trimethoxyflavone. The core crossover genes obtained by PPI and the core crossover genes obtained by the "active ingredient-crossover gene" network are intersected to obtain the three most important core genes (PTGS2, STAT1, HSP90AA1). AM may act on PTGS2, STAT1, HSP90AA1, etc. through active components such as acacetin, wogonin, baicalein, bis2S)-2-ethylhexyl) benzene-1,2-dicarboxylate and 5,2'-Dihydroxy-6,7,8-trimethoxyflavone to activate IL-17 signaling pathway, Th17 cell differentiation, Necroptosis, NOD-like receptor signaling pathway, Kaposi sarcoma-associated herpesvirus infection, and VEGF signaling pathway and other signaling pathways to achieve the effect of treating vitiligo and COVID-19.

Significance of Catecholamine Biosynthetic/Metabolic Pathway in SARS-CoV-2 Infection and COVID-19 Severity

The SARS-CoV-2 infection was previously associated with the expression of the dopamine biosynthetic enzyme L-Dopa decarboxylase (DDC). Specifically, a negative correlation was detected between DDC mRNA and SARS-CoV-2 RNA levels in in vitro infected epithelial cells and the nasopharyngeal tissue of COVID-19 patients with mild/no symptoms. However, DDC, among other genes related to both DDC expression and SARS-CoV-2-infection (ACE2, dACE2, EPO), was upregulated in these patients, possibly attributed to an orchestrated host antiviral response. Herein, by comparing DDC expression in the nasopharyngeal swab samples of severe/critical to mild COVID-19 cases, we showed a 20 mean-fold reduction, highlighting the importance of the expression of this gene as a potential marker of COVID-19 severity. Moreover, we identified an association of SARS-CoV-2 infection with the expression of key catecholamine biosynthesis/metabolism-related genes, in whole blood samples from hospitalized patients and in cultured cells. Specifically, viral infection downregulated the biosynthetic part of the dopamine pathway (reduction in DDC expression up to 7.5 mean-fold), while enhanced the catabolizing part (increase in monoamine oxidases A and B expression up to 15 and 10 mean-fold, respectively) in vivo, irrespectively of the presence of comorbidities. In accordance, dopamine levels in the sera of severe cases were reduced (up to 3.8 mean-fold). Additionally, a moderate positive correlation between DDC and MAOA mRNA levels (r = 0.527, p < 00001) in the blood was identified upon SARS-CoV-2-infection. These observations were consistent to the gene expression data from SARS-CoV-2-infected Vero E6 and A549 epithelial cells. Furthermore, L-Dopa or dopamine treatment of infected cells attenuated the virus-derived cytopathic effect by 55% and 59%, respectively. The SARS-CoV-2 mediated suppression of dopamine biosynthesis in cell culture was, at least in part, attributed to hypoxia-like conditions triggered by viral infection. These findings suggest that L-Dopa/dopamine intake may have a preventive or therapeutic value for COVID-19 patients.

Chemotherapy induces ACE2 expression in breast cancer via the ROS-AKT-HIF-1α signaling pathway: a potential prognostic marker for breast cancer patients receiving chemotherapy

Background

Angiotensin-converting enzyme 2 (ACE2) is a key enzyme of the renin-angiotensin system and a well-known functional receptor for the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into host cells. The COVID-19 pandemic has brought ACE2 into the spotlight, and ACE2 expression in tumors and its relationship with SARS-COV-2 infection and prognosis of cancer patients have received extensive attention. However, the association between ACE2 expression and tumor therapy and prognosis, especially in breast cancer, remains ambiguous and requires further investigation. We have previously reported that ACE2 is elevated in drug-resistant breast cancer cells, but the exact function of ACE2 in drug resistance and progression of this malignant disease has not been explored.

Methods

The expression of ACE2 and HIF-1α in parental and drug-resistant breast cancer cells under normoxic and hypoxic conditions was analyzed by Western blot and qRT-PCR methods. The protein levels of ACE2 in plasma samples from breast cancer patients were examined by ELISA. The relationship between ACE2 expression and breast cancer treatment and prognosis was analyzed using clinical specimens and public databases. The reactive oxygen species (ROS) levels in breast cancer cells were measured by using a fluorescent probe. Small interfering RNAs (siRNAs) or lentivirus-mediated shRNA was used to silence ACE2 and HIF-1α expression in cellular models. The effect of ACE2 knockdown on drug resistance in breast cancer was determined by Cell Counting Kit 8 (CCK-8)-based assay, colony formation assay, apoptosis and EdU assay.

Results

ACE2 expression is relatively low in breast cancer cells, but increases rapidly and specifically after exposure to anticancer drugs, and remains high after resistance is acquired. Mechanistically, chemotherapeutic agents increase ACE2 expression in breast cancer cells by inducing intracellular ROS production, and increased ROS levels enhance AKT phosphorylation and subsequently increase HIF-1α expression, which in turn upregulates ACE2 expression. Although ACE2 levels in plasma and cancer tissues are lower in breast cancer patients compared with healthy controls, elevated ACE2 in patients after chemotherapy is a predictor of poor treatment response and an unfavorable prognostic factor for survival in breast cancer patients.

Conclusion

ACE2 is a gene in breast cancer cells that responds rapidly to chemotherapeutic agents through the ROS-AKT-HIF-1α axis. Elevated ACE2 modulates the sensitivity of breast cancer cells to anticancer drugs by optimizing the balance of intracellular ROS. Moreover, increased ACE2 is not only a predictor of poor response to chemotherapy, but is also associated with a worse prognosis in breast cancer patients. Thus, our findings provide novel insights into the spatiotemporal differences in the function of ACE2 in the initiation and progression of breast cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03716-w.

The non-functional ACE2 isoform, but not the SARS-CoV-2 receptor, is induced as an interferon-stimulated gene, in SARS-CoV-2 infected adults

The recently discovered truncated, non-functional, ACE2 transcript (dACE2), but not the full-length ACE2 (f-lACE2), is induced by IFNs in differentiated airway cells. We measured expression of both ACE2 isoforms in SARS-CoV-2 positive and negative subjects, in relation to Interferon-stimulated genes. A significant activation of dACE2 transcript was found, in SARS-CoV-2 positive adults either hospitalized or not, showing a positive correlation with ISG15; f-lACE2 expression was weakly activated and not ISG-related. We confirmed a specific activation of dACE2 transcript in nasopharyngeal cells, related to the mucosal IFN response.

The Evolutionary Dance between Innate Host Antiviral Pathways and SARS-CoV-2

Compared to what we knew at the start of the SARS-CoV-2 global pandemic, our understanding of the interplay between the interferon signaling pathway and SARS-CoV-2 infection has dramatically increased. Innate antiviral strategies range from the direct inhibition of viral components to reprograming the host’s own metabolic pathways to block viral infection. SARS-CoV-2 has also evolved to exploit diverse tactics to overcome immune barriers and successfully infect host cells. Herein, we review the current knowledge of the innate immune signaling pathways triggered by SARS-CoV-2 with a focus on the type I interferon response, as well as the mechanisms by which SARS-CoV-2 impairs those defenses.

ACE2 overexpressing mesenchymal stem cells alleviates COVID-19 lung injury by inhibiting pyroptosis

Mesenchymal stem cells (MSCs) have shown some efficacy in the COVID-19 treatment. We proposed that exogenous supplementation of ACE2 via MSCs (ACE2-MSCs) might have better therapeutic effects. We constructed SARS-CoV-2 spike glycoprotein stably transfected AT-II and Beas-2B cells and used SARS-CoV-2 spike pseudovirus to infect hACE2 transgenic mice. The results showed that spike glycoprotein transfection triggers the release of apoptotic bodies and formation of membrane pores in pyroptosis. Inflammatory factors and pyroptosis factors were highly upregulated by spike glycoprotein transfection. SARS-CoV-2 spike pseudovirus worsened lung injury and increased the main factors of cytokine storm and pyroptosis. Compared to using MSCs or rh-ACE2 alone, the administration of ACE2-MSCs could significantly reduce these factors better and alleviate lung injury in vivo and in vitro, which might be because of the increased activities of secretory ACE2. Our proposal is a promising therapeutic solution for preclinical or clinical research.

Role of ISG15 post-translational modification in immunity against Mycobacterium tuberculosis infection

ISG15 encoded by a type I interferon (IFN) inducible gene mediates an important cellular process called ISGylation. ISGylation emerges as a powerful host tactic against intracellular pathogens like Mycobacterium tuberculosis (Mtb). However, the exact role of ISGylation in immunity remains elusive. To shed light on how ISGylation, which is both interesting and complex, participates in immunity against Mtb, this manuscript summarized the current knowledge about the structural characteristics and targets of ISG15 and how ISGylation cross-talks with other host post-translational modifications to exert its effect.

Understanding on the possible routes for SARS CoV-2 invasion via ACE2 in the host linked with multiple organs damage

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), accountable for causing the coronavirus diseases 2019 (COVID-19), is already declared as a pandemic disease globally. Like previously reported SARS-CoV strain, the novel SARS-CoV-2 also initiates the viral pathogenesis via docking viral spike-protein with the membranal angiotensin-converting enzyme 2 (ACE2) - a receptor on variety of cells in the human body. Therefore, COVID-19 is broadly characterized as a disease that targets multiple organs, particularly causing acute complications via organ-specific pathogenesis accompanied by destruction of ACE2+ cells, including alveolus, cardiac microvasculature, endothelium, and glomerulus. Under such circumstances, the high expression of ACE2 in predisposing individuals associated with anomalous production of the renin-angiotensin system (RAS) may promote enhanced viral load in COVID-19, which comparatively triggers excessive apoptosis. Furthermore, multi-organ injuries were found linked to altered ACE2 expression and inequality between the ACE2/angiotensin-(1-7)/mitochondrial Ang system (MAS) and renin-angiotensin-system (RAS) in COVID-19 patients. However, the exact pathogenesis of multi-organ damage in COVID-19 is still obscure, but several perspectives have been postulated, involving altered ACE2 expression linked with direct/indirect damages by the virus-induced immune responses, such as cytokinin storm. Thus, insights into the invasion of a virus with respect to ACE2 expression site can be helpful to simulate or understand the possible complications in the targeted organ during viral infection. Hence, this review summarizes the multiple organs invasion by SARS CoV-2 linked with ACE2 expression and their consequences, which can be helpful in the management of the COVID-19 pathogenesis under life-threatening conditions.

Maternal COVID-19 Vaccination and Its Potential Impact on Fetal and Neonatal Development

Vaccines have been developed at "warp speed" to combat the COVID-19 pandemic caused by the SARS-CoV-2 coronavirus. Although they are considered the best approach for preventing mortality, when assessing the safety of these vaccines, pregnant women have not been included in clinical trials. Thus, vaccine safety for this demographic, as well as for the developing fetus and neonate, remains to be determined. A global effort has been underway to encourage pregnant women to get vaccinated despite the uncertain risk posed to them and their offspring. Given this, post-hoc data collection, potentially for years, will be required to determine the outcomes of COVID-19 and vaccination on the next generation. Most COVID-19 vaccine reactions include injection site erythema, pain, swelling, fatigue, headache, fever and lymphadenopathy, which may be sufficient to affect fetal/neonatal development. In this review, we have explored components of the first-generation viral vector and mRNA COVID-19 vaccines that are believed to contribute to adverse reactions and which may negatively impact fetal and neonatal development. We have followed this with a discussion of the potential for using an ovine model to explore the long-term outcomes of COVID-19 vaccination during the prenatal and neonatal periods.