[Ferroptosis-associated lesion as a potential target for cardiovascular disease: A review].

Cell death is an important feature of the development of multicellular organisms, a critical factor in the occurrence of cardiovascular diseases. Understanding the mechanisms that control cell death is crucial to determine its role in the development of the pathological process. However, the most well-known types of cell death cannot fully explain the pathophysiology of heart disease. Understanding how cardiomyocytes die and why their regeneration is limited is an important area of research. Ferroptosis is an iron-dependent cell death that differs from apoptosis, necrosis, autophagy, and other forms of cell death in terms of morphology, metabolism, and protein expression. Ferroptotic cell death is characterized by the accumulation of reactive oxygen species resulting from lipid peroxidation and subsequent oxidative stress, which can be prevented by iron chelates (eg, deferoxamine) and small lipophilic antioxidants (eg, ferrostatin, liproхstatin). In recent years, many studies have been carried out on ferroptosis in the context of the development of atherosclerosis, myocardial infarction, heart failure, and other diseases. In addition to cardiovascular diseases, the review also presents data on the role of ferroptosis in the development of other socially significant diseases, such as COVID-19, chronic obstructive pulmonary disease. With the study of ferroptosis, it turned out that ferroptosis participates in the development of bacterial infection associated with the persistence in the host body of Pseudomonas aeruginosa. The review summarizes the recent advances in the study of ferroptosis, characterizing this type of cell death as a novel therapeutic target.

SARS-CoV-2 induces cardiomyocyte apoptosis and inflammation but can be ameliorated by ACE inhibitor Captopril.

Although the clinical manifestation of COVID-19 is mainly respiratory symptoms, approximately 20% of patients suffer from cardiac complications. COVID-19 patients with cardiovascular disease have higher severity of myocardial injury and poor outcomes. The underlying mechanism of myocardial injury caused by SARS-CoV-2 infection remains unclear. Using a non-transgenic mouse model infected with Beta variant (B.1.351), we found that the viral RNA could be detected in lungs and hearts of infected mice. Pathological analysis showed thinner ventricular wall, disorganized and ruptured myocardial fiber, mild inflammatory infiltration, and mild epicardia or interstitial fibrosis in hearts of infected mice. We also found that SARS-CoV-2 could infect cardiomyocytes and produce infectious progeny viruses in human pluripotent stem cell-derived cardiomyocyte-like cells (hPSC-CMs). SARS-CoV-2 infection caused apoptosis, reduction of mitochondrial integrity and quantity, and cessation of beating in hPSC-CMs. In order to dissect the mechanism of myocardial injury caused by SARS-CoV-2 infection, we employed transcriptome sequencing of hPSC-CMs at different time points after viral infection. Transcriptome analysis showed robust induction of inflammatory cytokines and chemokines, up-regulation of MHC class I molecules, activation of apoptosis signaling and cell cycle arresting. These may cause aggravate inflammation, immune cell infiltration, and cell death. Furthermore, we found that Captopril (hypotensive drugs targeting ACE) treatment could alleviate SARS-CoV-2 induced inflammatory response and apoptosis in cardiomyocytes via inactivating TNF signaling pathways, suggesting Captopril may be beneficial for reducing COVID-19 associated cardiomyopathy. These findings preliminarily explain the molecular mechanism of pathological cardiac injury caused by SARS-CoV-2 infection, providing new perspectives for the discovery of antiviral therapeutics.

Classification of tuberculosis-related programmed cell death-related patient subgroups and associated immune cell profiling.

Background: Tuberculosis (TB) is the deadliest communicable disease in the world with the exception of the ongoing COVID-19 pandemic. Programmed cell death (PCD) patterns play key roles in the development and progression of many disease states such that they may offer value as effective biomarkers or therapeutic targets that can aid in identifying and treating TB patients. Materials and methods: The Gene Expression Omnibus (GEO) was used to gather TB-related datasets after which immune cell profiles in these data were analyzed to examine the potential TB-related loss of immune homeostasis. Profiling of differentially expressed PCD-related genes was performed, after which candidate hub PCD-associated genes were selected via a machine learning approach. TB patients were then stratified into two subsets based on the expression of PCD-related genes via consensus clustering. The potential roles of these PCD-associated genes in other TB-related diseases were further examined. Results: In total, 14 PCD-related differentially expressed genes (DEGs) were identified and highly expressed in TB patient samples and significantly correlated with the abundance of many immune cell types. Machine learning algorithms enabled the selection of seven hub PCD-related genes that were used to establish PCD-associated patient subgroups, followed by the validation of these subgroups in independent datasets. These findings, together with GSVA results, indicated that immune-related pathways were significantly enriched in TB patients exhibiting high levels of PCD-related gene expression, whereas metabolic pathways were significantly enriched in the other patient group. Single cell RNA-seq (scRNA-seq) further highlighted significant differences in the immune status of these different TB patient samples. Furthermore, we used CMap to predict five potential drugs for TB-related diseases. Conclusion: These results highlight clear enrichment of PCD-related gene expression in TB patients and suggest that this PCD activity is closely associated with immune cell abundance. This thus indicates that PCD may play a role in TB progression through the induction or dysregulation of an immune response. These findings provide a foundation for further research aimed at clarifying the molecular drivers of TB, the selection of appropriate diagnostic biomarkers, and the design of novel therapeutic interventions aimed at treating this deadly infectious disease.

Boesenbergia stenophylla-Derived Stenophyllol B Exerts Antiproliferative and Oxidative Stress Responses in Triple-Negative Breast Cancer Cells with Few Side Effects in Normal Cells.

Triple-negative breast cancer (TNBC) is insensitive to target therapy for non-TNBC and needs novel drug discovery. Extracts of the traditional herb Boesenbergia plant in Southern Asia exhibit anticancer effects and contain novel bioactive compounds but merely show cytotoxicity. We recently isolated a new compound from B. stenophylla, stenophyllol B (StenB), but the impact and mechanism of its proliferation-modulating function on TNBC cells remain uninvestigated. This study aimed to assess the antiproliferative responses of StenB in TNBC cells and examine the drug safety in normal cells. StenB effectively suppressed the proliferation of TNBC cells rather than normal cells in terms of an ATP assay. This preferential antiproliferative function was alleviated by pretreating inhibitors for oxidative stress (N-acetylcysteine (NAC)) and apoptosis (Z-VAD-FMK). Accordingly, the oxidative-stress-related mechanisms were further assessed. StenB caused subG1 and G2/M accumulation but reduced the G1 phase in TNBC cells, while normal cells remained unchanged between the control and StenB treatments. The apoptosis behavior of TNBC cells was suppressed by StenB, whereas that of normal cells was not suppressed according to an annexin V assay. StenB-modulated apoptosis signaling, such as for caspases 3, 8, and 9, was more significantly activated in TNBC than in normal cells. StenB also caused oxidative stress in TNBC cells but not in normal cells according to a flow cytometry assay monitoring reactive oxygen species, mitochondrial superoxide, and their membrane potential. StenB induced greater DNA damage responses (γH2AX and 8-hydroxy-2-deoxyguanosine) in TNBC than in normal cells. All these StenB responses were alleviated by NAC pretreatment. Collectively, StenB modulated oxidative stress responses, leading to the antiproliferation of TNBC cells with little cytotoxicity in normal cells.

Iron as a therapeutic target in chronic liver disease.

It was clearly realized more than 50 years ago that iron deposition in the liver may be a critical factor in the development and progression of liver disease. The recent clarification of ferroptosis as a specific form of regulated hepatocyte death different from apoptosis and the description of ferritinophagy as a specific variation of autophagy prompted detailed investigations on the association of iron and the liver. In this review, we will present a brief discussion of iron absorption and handling by the liver with emphasis on the role of liver macrophages and the significance of the iron regulators hepcidin, transferrin, and ferritin in iron homeostasis. The regulation of ferroptosis by endogenous and exogenous mod-ulators will be examined. Furthermore, the involvement of iron and ferroptosis in various liver diseases including alcoholic and non-alcoholic liver disease, chronic hepatitis B and C, liver fibrosis, and hepatocellular carcinoma (HCC) will be analyzed. Finally, experimental and clinical results following interventions to reduce iron deposition and the promising manipulation of ferroptosis will be presented. Most liver diseases will be benefited by ferroptosis inhibition using exogenous inhibitors with the notable exception of HCC, where induction of ferroptosis is the desired effect. Current evidence mostly stems from in vitro and in vivo experimental studies and the need for well-designed future clinical trials is warranted.

Fangchinoline Exerts Anticancer Effects on Colorectal Cancer Cells by Evoking Cell Apoptosis via Endoplasmic Reticulum Stress.

We studied the anti-tumor effect of fangchinoline (FAN) against human colorectal cancer cell lines CCL-244 and SW480 and analyzed the mechanism of FAN action. The cell viability and apoptosis were assessed by MTT test and Annexin V-PI staining; caspase-3 activity was measured by Western blotting. The expression of endoplasmic reticulum stress-related proteins was assessed by real-time PCR, Western blotting, and gene transfection. It was found that FAN inhibited cell growth and induced apoptosis in human colorectal cancer cell lines CCL-244 and SW480 in a dose-dependent manner. The caspase-3 inhibitor Ac-DEVD-CHO could reverse the inhibitory effect of FAN. Moreover, FAN significantly increased the expression of endoplasmic reticulum stress-related proteins p-PERK, p-eIF2α, ATF4, and CHOP in CCL-244 and SW480 cells. In addition, endoplasmic reticulum stress inhibitor 4-phenylbutyric acid or CHOP knockdown could prevent FAN-induced apoptosis. Thus, FAN induced apoptosis of human colorectal cancer through activation of endoplasmic reticulum stress.

SerpinA3K Deficiency Reduces Oxidative Stress in Acute Kidney Injury.

We previously showed that SerpinA3K is present in urine from rats and humans with acute kidney injury (AKI) and chronic kidney disease (CKD). However, the specific role of SerpinA3K during renal pathophysiology is unknown. To begin to understand the role of SerpinA3K on AKI, SerpinA3K-deficient (KOSA3) mice were studied 24 h after inducing ischemia/reperfusion (I/R) and compared to wild type (WT) mice. Four groups were studied: WT+S, WT+IR, KOSA3+S, and KOSA3+IR. As expected, I/R increased serum creatinine and BUN, with a GFR reduction in both genotypes; however, renal dysfunction was ameliorated in the KOSA3+IR group. Interestingly, the increase in UH2O2 induced by I/R was not equally seen in the KOSA3+IR group, an effect that was associated with the preservation of antioxidant enzymes' mRNA levels. Additionally, FOXO3 expression was initially greater in the KOSA3 than in the WT group. Moreover, the increase in BAX protein level and the decrease in Hif1a and Vegfa induced by I/R were not observed in the KOSA3+IR group, suggesting that these animals have better cellular responses to hypoxic injury. Our findings suggest that SerpinA3K is involved in the renal oxidant response, HIF1α/VEGF pathway, and cell apoptosis.

Triacetyl Resveratrol Inhibits PEDV by Inducing the Early Apoptosis In Vitro.

PEDV represents an ancient Coronavirus still causing huge economic losses to the porcine breeding industry. Resveratrol has excellent antiviral effects. Triacetyl resveratrol (TCRV), a novel natural derivative of resveratrol, has been recently discovered, and its pharmacological effects need to be explored further. This paper aims to explore the relationship between PEDV and TCRV, which offers a novel strategy in the research of antivirals. In our study, Vero cells and IPEC-J2 cells were used as an in vitro model. First, we proved that TCRV had an obvious anti-PEDV effect and a strong inhibitory effect at different time points. Then, we explored the mechanism of inhibition of PEDV infection by TCRV. Our results showed that TCRV could induce the early apoptosis of PEDV-infected cells, in contrast to PEDV-induced apoptosis. Moreover, we observed that TCRV could promote the expression and activation of apoptosis-related proteins and release mitochondrial cytochrome C into cytoplasm. Based on these results, we hypothesized that TCRV induced the early apoptosis of PEDV-infected cells and inhibited PEDV infection by activating the mitochondria-related caspase pathway. Furthermore, we used the inhibitors Z-DEVD-FMK and Pifithrin-α (PFT-α) to support our hypothesis. In conclusion, the TCRV-activated caspase pathway triggered early apoptosis of PEDV-infected cells, thereby inhibiting PEDV infections.

NLRP3 Inflammasome: A key contributor to the inflammation formation.

Inflammation is an important part of the development of various organ diseases. The inflammasome, as an innate immune receptor, plays an important role in the formation of inflammation. Among various inflammasomes, the NLRP3 inflammasome is the most well studied. The NLRP3 inflammasome is composed of skeletal protein NLRP3, apoptosis-associated speck-like protein (ASC) and pro-caspase-1. There are three types of activation pathways: (1) "classical" activation pathway; (2) "non-canonical" activation pathway; (3) "alternative" activation pathway. The activation of NLRP3 inflammasome is involved in many inflammatory diseases. A variety of factors (such as genetic factors, environmental factors, chemical factors, viral infection, etc.) have been proved to activate NLRP3 inflammasome and promote the inflammatory response of the lung, heart, liver, kidney and other organs in the body. Especially, the mechanism of NLRP3 inflammation and its related molecules in its associated diseases remains not to be summarized, namely they may promote or delay inflammatory diseases in different cells and tissues. This article reviews the structure and function of the NLRP3 inflammasome and its role in various inflammations, including inflammations caused by chemically toxic substances.

SIRT6 attenuates LPS-induced inflammation and apoptosis of lung epithelial cells in acute lung injury through ACE2/STAT3/PIM1 signaling.

BACKGROUND: Acute lung injury (ALI) is a severe and fatal respiratory disease. SIRT6 exerts pivotal activities in the process of lung diseases, but whether SIRT6 impacts ALI has not been covered. METHODS: Lentivirus recombinant expressing vector SIRT6 gene (Lent-SIRT6) was constructed in mice, and there were control, lipopolysaccharide (LPS), LPS + Vehicle, and LPS + Lent SIRT6 groups. RT-qPCR and western blot detected SIRT6 expression in lung tissues. HE staining observed pathological alternations in lung tissues. Wet-to-dry ratio of the lungs was then measured. The cell count of bronchoalveolar lavage fluid (BALF) was evaluated. Serum inflammation was examined with enzyme-linked immunosorbent assay, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and western blot were to measure apoptosis. Western blot tested the expression of ACE2/STAT3/PIM1 signaling-associated factors. At the cellular level, LPS was used to induce lung epithelial cells BEAS-2B to establish cell injury models. SIRT6 was overexpressed and ACE2 expression was inhibited by cell transfection, and the mechanism of SIRT6 in LPS-induced lung injury model was further explored by Cell Counting Kit-8 (CCK-8), western blot, quantitative reverse-transcription polymerase chain reaction, TUNEL, and other techniques. RESULTS: The results of animal experiments showed that SIRT6 overexpression could reduce LPS-induced lung pathological injury, pulmonary edema, and BALF cell ratio and attenuate LPS-induced inflammatory response and cell apoptosis. In the above process, ACE2, STAT3, p-STAT3, and PIM1 expression were affected. In cell experiments, SIRT6 expression was reduced in LPS-induced BEAS-2B cells. Inhibition of ACE2 expression could reverse the inhibitory effect of SIRT6 overexpression on ACE2/STAT3/PIM1 pathway, and cellular inflammatory response and apoptosis. CONCLUSION: SIRT6 eased LPS-evoked inflammation and apoptosis of lung epithelial cells in ALI through ACE2/STAT3/PIM1 signaling.

Matrine combined with Osthole inhibited the PERK apoptosis of splenic lymphocytes in PCV2-infected mice model.

BACKGROUND: Porcine circovirus type 2 (PCV2) is one of the major pathogens commonly found in pigs, which causes immunosuppression and apoptosis. Vaccination and a single drug cannot totally prevent and treat PCV2 infection. Our previous in vitro study reported that the synergistic anti-PCV2 effect of Matrine and Osthole was better than that of Matrine or Osthole alone, This study was aimed to evaluate the synergistic anti-PCV2 effect as well as the underline molecular mechanism of Matrine and Osthole in Kunming (KM) mice model infected with PCV2. KM mice were randomly divided into 8 groups namely control group, PCV2 infected, Matrine combined with Osthole high dose treatment (40 mg/kg + 12 mg/kg), medium dose treatment (20 mg/kg + 6 mg/kg), low dose treatment (10 mg/kg + 3 mg/kg), Matrine treatment (40 mg/kg), Osthole treatment (12 mg/kg) and Ribavirin positive control (40 mg/kg) groups. PCV2 was intraperitoneally (i.p.) injected in all mice except the control group. 5 days of post-infection (dpi), mice in different treatment groups were injected i.p. with various doses of Matrine, Osthole and Ribavirin once daily for the next 5 consecutive days. RESULTS: The synergistic inhibitory effect of Matrine and Osthole on PCV2 replication in mouse liver was significantly heigher than that of Matrine and Osthole alone. The expression of GRP78, p-PERK, p-eIF2α, ATF4, CHOP, cleaved caspase-3 and Bax proteins were significantly reduced, while that of Bcl-2 was significantly increased in Matrine combined with Osthole groups, which alleviated the pathological changes caused by PCV2, such as interstitial pneumonia, loss of spleen lymphocytes, infiltration of macrophages and eosinophils. CONCLUSIONS: The synergistic anti-apoptotic effect of Matrine and Osthole was better than their alone effect, Both Matrine and Osthole had directly inhibited the expression of PCV2 Cap and the apoptosis of spleen cells induced by PCV2 Cap through the PERK pathway activated by endoplasmic reticulum (ER) GRP78. These results provided a new insight to control PCV2 infection and provide good component prescription candidate for the development of novel anti-PCV2 drugs.

The novel Nsp9-interacting host factor H2BE promotes PEDV replication by inhibiting endoplasmic reticulum stress-mediated apoptosis.

Porcine epidemic diarrhoea (PED) caused by porcine epidemic diarrhoea virus (PEDV) has led to significant economic losses in the swine industry worldwide. Histone Cluster 2, H2BE (HIST2H2BE), the main protein component in chromatin, has been proposed to play a key role in apoptosis. However, the relationship between H2BE and PEDV remains unclear. In this study, H2BE was shown to bind and interact with PEDV nonstructural protein 9 (Nsp9) via immunoprecipitation-mass spectrometry (IP-MS). Next, we verified the interaction of Nsp9 with H2BE by immunoprecipitation and immunofluorescence. H2BE colocalized with Nsp9 in the cytoplasm and nuclei. PEDV Nsp9 upregulated the expression of H2BE by inhibiting the expression of IRX1. We demonstrated that overexpression of H2BE significantly promoted PEDV replication, whereas knockdown of H2BE by small interfering RNA (siRNA) inhibited PEDV replication. Overexpression of H2BE led to significantly inhibited GRP78 expression, phosphorylated PERK (p-PERK), phosphorylated eIF2 (p-eIF2), phosphorylated IRE1 (p-IRE1), and phosphorylated JNK (p-JNK); negatively regulated CHOP and Bax expression and caspase-9 and caspase-3 cleavage; and promoted Bcl-2 production. Knocking down H2BE exerted the opposite effects. Furthermore, we found that after deletion of amino acids 1-28, H2BE did not promote PEDV replication. In conclusion, these studies revealed the mechanism by which H2BE is associated with ER stress-mediated apoptosis to regulate PEDV replication. Nsp9 upregulates H2BE. H2BE plays a role in inhibiting apoptosis and thus facilitating viral replication, which depends on the N-terminal region of H2BE (amino acids 1-28). These findings provide a reference for host-PEDV interactions and offer the possibility for developing strategies for PEDV decontamination and prevention.

GRAMD4 regulates PEDV-induced cell apoptosis inhibiting virus replication via the endoplasmic reticulum stress pathway.

Porcine epidemic diarrhea (PED) caused by the porcine epidemic diarrhea virus (PEDV) has caused huge losses in the swine industry worldwide. Glucosyltransferase Rab-like GTPase activator and myotubularin domain containing 4 (GRAMD4) is a proapoptotic protein, which replaced p53 inducing mitochondrial apoptosis. However, the relationship between GRAMD4 and PEDV has not been reported. Here, we aimed to investigate the potential role of GRAMD4 during PEDV infection. In this study, we used co-immunoprecipitation (co-IP) and mass spectrometry to identify GRAMD4 interaction with PEDV non-structural protein 6 (NSP6). Immunoprecipitation and laser confocal microscopy were utilized to demonstrate that GRAMD4 interacts with NSP6. NSP6 reduces GRAMD4 production through PERK and IRE1 pathway-mediated apoptosis. We demonstrated that overexpression of GRAMD4 effectively impaired the replication of PEDV, whereas knockdown of GRAMD4 facilitated the replication of PEDV. Overexpression of GRAMD4 increased GRP78, phosphorylated PERK (p-PERK), phosphorylated IRE1(p-IRE1) levels, promoted CHOP, phosphorylated JNK (p-JNK), Bax expression, caspase 9 and caspase 3 cleavage, and inhibited Bcl-2 production. Knockdown of GRAMD4 has the opposite effect. Finally, deletion of the GRAM domain of GRAMD4 cannot cause endoplasmic reticulum stress (ER stress)-mediated apoptosis and inhibit virus replication. In conclusion, these studies revealed the mechanism by which GRAMD4 was associated with ER stress and apoptosis regulating PEDV replication. NSP6 acted as a potential down-regulator of GRAMD4 and promoted the degradation of GRAMD4. GRAMD4 played a role in facilitating apoptosis and restricting virus replication, and the GRAM domain was required. These findings provided a reference for host-PEDV interactions and offered the possibility for PEDV decontamination and prevention.

A new perspective on the potential application of RIPK1 in the treatment of sepsis.

RIPK1 is a global cellular sensor that can determine the survival of cells. Generally, RIPK1 can induce cell apoptosis and necroptosis through TNF, Fas and lipopolysaccharide stimulation, while its scaffold function can sense the fluctuation of cellular energy and promote cell survival. Sepsis is a nonspecific disease that seriously threatens human health. There is some dispute in the literature about the role of RIPK1 in sepsis. In this review, the authors attempt to comprehensively discuss the differential results for RIPK1 in sepsis by summarizing the underlying molecular mechanism and putting forward a tentative idea as to whether RIPK1 can serve as a biomarker for the monitoring of treatment and progression in sepsis.

Sepsis is a syndrome that poses a serious threat to human life and health and is classified as a medical emergency by the WHO. RIPK1 can regulate the onset of apoptosis and necrosis in several ways and is known as a sensor of cell survival status. A series of clinical trials of RIPK1 drugs has been conducted this year and have demonstrated promising efficacy in inflammatory diseases, in particular. In this paper, the authors summarize recent studies on the function and mechanism of RIPK1 in sepsis and combine them with the progress in RIPK1 drug development to provide information for the study of RIPK1 in sepsis.

HSPA5 Promotes the Proliferation, Metastasis and Regulates Ferroptosis of Bladder Cancer.

Heat shock protein family A (HSP70) member 5 (HSPA5) is aberrantly expressed in various tumors and closely associated with the progression and prognosis of cancer. Nevertheless, its role in bladder cancer (BCa) remains elusive. The results of our study demonstrated that HSPA5 was upregulated in BCa and correlated with patient prognosis. Cell lines with low expression level of HSPA5 were constructed to explore the role of this protein in BCa. HSPA5 knockdown promoted apoptosis and retarded the proliferation, migration and invasion of BCa cells by regulating the VEGFA/VEGFR2 signaling pathway. In addition, overexpression of VEGFA alleviated the negative effect of HSPA5 downregulation. Moreover, we found that HSPA5 could inhibit the process of ferroptosis through the P53/SLC7A11/GPX4 pathway. Hence, HSPA5 can facilitate the progression of BCa and may be used as a novel biomarker and latent therapeutic target in the clinic.

Reactive oxygen species are associated with the inhibitory effect of N-(4-hydroxyphenyl)-retinamide on the entry of the severe acute respiratory syndrome-coronavirus 2.

N-(4-hydroxyphenyl)-retinamide (4-HPR) inhibits the dihydroceramide Δ4-desaturase 1 (DEGS1) enzymatic activity. We previously reported that 4-HPR suppresses the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) spike protein-mediated membrane fusion through a decrease in membrane fluidity in a DEGS1-independent manner. However, the precise mechanism underlying the inhibition of viral entry by 4-HPR remains unclear. In this study, we examined the role of reactive oxygen species (ROS) in the inhibition of membrane fusion by 4-HPR because 4-HPR is a well-known ROS-inducing agent. Intracellular ROS generation was found to be increased in the target cells in a cell-cell fusion assay after 4-HPR treatment, which was attenuated by the addition of the antioxidant, α-tocopherol (TCP). The reduction in membrane fusion susceptibility by 4-HPR treatment in the cell-cell fusion assay was alleviated by TCP addition. Furthermore, fluorescence recovery after photobleaching analysis showed that the lateral diffusion of glycosylphosphatidylinositol-anchored protein and SARS CoV-2 receptor was reduced by 4-HPR treatment and restored by TCP addition. These results indicate that the decrease in SARS-CoV-2 spike protein-mediated membrane fusion and membrane fluidity by 4-HPR was due to ROS generation. Taken together, these results demonstrate that ROS production is associated with the 4-HPR inhibitory effect on SARS-CoV-2 entry.

SARS-CoV-2 SUD2 and Nsp5 Conspire to Boost Apoptosis of Respiratory Epithelial Cells via an Augmented Interaction with the G-Quadruplex of BclII.

The molecular mechanisms underlying how SUD2 recruits other proteins of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to exert its G-quadruplex (G4)-dependent pathogenic function is unknown. Herein, Nsp5 was singled out as a binding partner of the SUD2-N+M domains (SUD2core) with high affinity, through the surface located crossing these two domains. Biochemical and fluorescent assays demonstrated that this complex also formed in the nucleus of living host cells. Moreover, the SUD2core-Nsp5 complex displayed significantly enhanced selective binding affinity for the G4 structure in the BclII promoter than did SUD2core alone. This increased stability exhibited by the tertiary complex was rationalized by AlphaFold2 and molecular dynamics analysis. In line with these molecular interactions, downregulation of BclII and subsequent augmented apoptosis of respiratory cells were both observed. These results provide novel information and a new avenue to explore therapeutic strategies targeting SARS-CoV-2. IMPORTANCE SUD2, a unique protein domain closely related to the pathogenesis of SARS-CoV-2, has been reported to bind with the G-quadruplex (G4), a special noncanonical DNA structure endowed with important functions in regulating gene expression. However, the interacting partner of SUD2, among other SARS-CoV-2 Nsps, and the resulting functional consequences remain unknown. Here, a stable complex formed between SUD2 and Nsp5 was fully characterized both in vitro and in host cells. Moreover, this complex had a significantly enhanced binding affinity specifically targeting the Bcl2G4 in the promoter region of the antiapoptotic gene BclII, compared with SUD2 alone. In respiratory epithelial cells, the SUD2-Nsp5 complex promoted BclII-mediated apoptosis in a G4-dependent manner. These results reveal fresh information about matched multicomponent interactions, which can be parlayed to develop new therapeutics for future relevant viral disease.

Evaluation of FAS and eNOS expression in COVID-19 placenta: histopathological and immunohistochemical study.

OBJECTIVE: In this study, the effects of cell adhesion, inflammation and apoptotic changes on fetal development in cases of COVID-19 placenta were investigated. PATIENTS AND METHODS: Placenta tissue samples from 15 COVID-19 and 15 healthy pregnant women were taken after delivery. Tissue samples were fixed in formaldehyde, then blocked with paraffin wax and 4-6 µm thick sections were cut and stained with Harris Hematoxylene-Eosin. Sections were stained with FAS antibody and endothelial nitric oxide synthase (eNOS) antibody. RESULTS: In COVID-19 placenta section, deterioration of the root villus basement membrane structure in the maternal region, decidua cells and syncytial cell degeneration, significant increase in fibrinoid tissue, endothelial dysfunction in free villi and intense congestion in blood vessels, increase in syncytial nodes and bridges were observed. In terms of inflammation, eNOS expression was increased in Hoffbauer cells, dilated blood vessels endothelial cells in chorionic villi, and surrounding inflammatory cells. Positive FAS expression was also increased in the basement membranes of root and free villi, syncytial bridge and nodes, and endothelial cells. CONCLUSIONS: The effect of COVID-19 caused an increase in eNOS activity and acceleration of the proapoptotic process and the deterioration of cell-membrane adhesion.

Transmissible Gastroenteritis Virus: An Update Review and Perspective.

Transmissible gastroenteritis virus (TGEV) is a member of the alphacoronavirus genus, which has caused huge threats and losses to pig husbandry with a 100% mortality in infected piglets. TGEV is observed to be recombining and evolving unstoppably in recent years, with some of these recombinant strains spreading across species, which makes the detection and prevention of TGEV more complex. This paper reviews and discusses the basic biological properties of TGEV, factors affecting virulence, viral receptors, and the latest research advances in TGEV infection-induced apoptosis and autophagy to improve understanding of the current status of TGEV and related research processes. We also highlight a possible risk of TGEV being zoonotic, which could be evidenced by the detection of CCoV-HuPn-2018 in humans.