Multi-functional BST2/tetherin against HIV-1, other viruses and LINE-1

Unphosphorylated STAT1 binds to the BST2 transcription promoter, promoting increased AKBA anchoring on HPMECs to alleviate ARDS

Although the drug therapeutic targets of acute respiratory distress syndrome (ARDS) are still unclear and no specific drugs for ARDS treatment have been found, some breakthroughs have been gradually made in the biological target pathways such as endothelial injury. The Traditional Chinese Medicine Systems Pharmacology (TCMSP) database suggests that Acetyl-11-keto-β-boswellic acid (AKBA), a processed product of boswellic acid, may be an effective intervention for ARDS. After preliminary in vitro and in vivo verification of the protective role of AKBA on ARDS, in order to explore the mechanism of AKBA in ARDS, we used transcriptomic and proteomic methods to explore its main targets, and used molecular docking and cell thermal shift assay (CETSA) to further reveal the potential value of bone marrow stromal cell antigen 2 (BST2) as a target. We subsequently examined the effect of AKBA targeting BST2 on tubule formation, cell proliferation (Colony formation and EdU assay), migration (transwell and scratch assays), apoptosis and autophagy levels both in vitro and in vivo, and protein changes (analyzed by Western blotting analysis). Our results show that the unphosphorylated signal transducers and transcription activation factors (U-STAT1) bins to the BST2 transcription promoter to encourage more AKBA anchoring the human pulmonary microvascular endothelial cells (HPMECs), thus inhibiting apoptosis and autophagy, promoting migration and tube formation, and restraining the cecal ligation and puncture (CLP) induced lung tissue damage in mice. In conclusion, AKBA treatment may be a potential strategy in the intervention of ARDS. Alternatively, BST2 may contribute to the anchoring of AKBA to HPMECs, and STAT1 as a transcription factor promoting BST2 expression may bind to its promoter.

A prospective self-controlled study on the alterations of the ocular surface and conjunctival transcriptomic profile associated with prolonged exposure to video display terminals

PURPOSE

To assess the impact of prolonged and intense exposure to video display terminals (VDTs) on ocular surface homeostasis.

METHODS

30 subjects limited daily VDT usage to less than 3 h for one week, then extended usage to more than 8 h/day for the next three weeks. Ocular symptoms and signs were evaluated weekly using the Ocular Surface Disease Index (OSDI) questionnaire and clinical examinations. Eyelid margins and meibomian glands were examined, and ocular surface samples were collected for transcriptomic analysis.

RESULTS

Average daily VDT time increased from 2.55 ± 0.46 h initially to 11.17 ± 2.45, 11.75 ± 2.63, and 10.89 ± 2.41 h over three weeks. The dry eye diagnosis rate rose from 6.67 % to 51.67 %. Total OSDI score (P = 0.008), symptoms score (P = 0.014), and visual function score (P = 0.002) significantly increased. Mean fluorescein break-up time (FBUT) decreased from 6.46s to 3.08s. Corneal fluorescein staining (CFS) score (P < 0.001) and lissamine green conjunctival staining (LCjs) score (P = 0.036) worsened. Ocular redness index (RI) increased at 1 week and 3 weeks (P = 0.007, P = 0.001). Telangiectasia scores of both upper and lower eyelid margins increased at 3 weeks (P = 0.002, P < 0.001). Meibomian gland orifice blockage worsened (P = 0.014, P = 0.002). Transcriptomic analysis revealed dynamic alterations in ocular surface gene expression, including inflammatory and hormonal responses. MUC5AC and TFF1 genes showed negative correlations with OSDI and conjunctival staining score, respectively.

CONCLUSION

Prolonged VDT exposure deteriorates ocular surface symptoms and signs, with significant inflammatory responses and hormonal activity indicating an imbalance in ocular surface homeostasis.

Subtype AD Recombinant HIV-1 Transmitted/Founder Viruses Are Less Sensitive to Type I Interferons than Subtype D

Initial interactions between HIV-1 and the immune system at mucosal exposure sites play a critical role in determining whether the virus is eliminated or progresses to establish systemic infection. The virus that successfully crosses the mucosal barrier to establish infection in the new host is referred to as the transmitted/founder (TF) virus. Following mucosal HIV-1 transmission, type 1 interferons (IFN-I) are rapidly induced at sites of initial virus replication. The resistance of TF variants to these antiviral effects of the IFN-I has been studied among HIV-1 subtypes B and C. However, their role in restricting HIV-1 replication among subtypes D and AD recombinant remains unexplored. This study assessed the sensitivity of HIV-1 subtype D and AD recombinant TF viruses to IFN-I by infecting peripheral blood mononuclear cells in vitro with infectious molecular clones of these viruses. Cells were exposed to varying concentrations of interferon-α and interferon-β, and viral replicative capacity was measured using HIV-1 p24 antigen ELISA from culture supernatants. Sensitivity to IFN-I was quantified based on viral replication levels. The results showed that interferon-α was more effective in inhibiting viral replication than interferon-β, regardless of the varying amounts of IFN-I used. However, recombinant AD viruses were found to be more resistant to the antiviral effects of IFN-I compared to subtype D viruses. These findings highlight the differential sensitivity of HIV-1 subtypes AD recombinant and D TF viruses to IFN-I and underscore the potential of IFN-I as a therapeutic strategy to target TF viruses and reduce HIV-1 transmission, particularly in populations where subtype D is prevalent.

Regulation of viral replication by host restriction factors

Viral infectious diseases, caused by numerous viruses including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A virus (IAV), enterovirus (EV), human immunodeficiency virus (HIV), hepatitis B virus (HBV), and human papillomavirus (HPV), pose a continuous threat to global health. As obligate parasites, viruses rely on host cells to replicate, and host cells have developed numerous defense mechanisms to counteract viral infection. Host restriction factors (HRFs) are critical components of the early antiviral response. These cellular proteins inhibit viral replication and spread by impeding essential steps in the viral life cycle, such as viral entry, genome transcription and replication, protein translation, viral particle assembly, and release. This review summarizes the current understanding of how host restriction factors inhibit viral replication, with a primary focus on their diverse antiviral mechanisms against a range of viruses, including SARS-CoV-2, influenza A virus, enteroviruses, human immunodeficiency virus, hepatitis B virus, and human papillomavirus. In addition, we highlight the crucial role of these factors in shaping the host-virus interactions and discuss their potential as targets for antiviral drug development.

A Better Understanding of the Clinical and Pathological Changes in Viral Retinitis: Steps to Improve Visual Outcomes

Infectious retinitis, though rare, poses a significant threat to vision, often leading to severe and irreversible damage. Various pathogens, including viruses, bacteria, tick-borne agents, parasites, and fungi, can cause this condition. Among these, necrotizing herpetic retinitis represents a critical spectrum of retinal infections primarily caused by herpes viruses such as varicella-zoster virus (VZV), herpes simplex virus (HSV), and cytomegalovirus (CMV). This review underscores the retina's susceptibility to viral infections, focusing on the molecular mechanisms through which herpetic viruses invade and damage retinal tissue, supported by clinical and preclinical evidence. We also identify existing knowledge gaps and propose future research directions to deepen our understanding and improve therapeutic outcomes.

Cytoadhesion of Plasmodium falciparum-Infected Red Blood Cells Changes the Expression of Cytokine-, Histone- and Antiviral Protein-Encoding Genes in Brain Endothelial Cells

Malaria remains a significant global health problem, mainly due to Plasmodium falciparum, which is responsible for most fatal infections. Infected red blood cells (iRBCs) evade spleen clearance by adhering to endothelial cells (ECs), triggering capillary blockage, inflammation, endothelial dysfunction and altered vascular permeability, prompting an endothelial transcriptional response. The iRBCIT4var04/HBEC-5i model, where iRBCs present IT4var04 (VAR2CSA) on their surface, was used to analyze the effects of iRBC binding on ECs at different temperature (37°C vs. 40°C). Binding of non-infected RBCs (niRBCs) and fever alone altered the expression of hundreds of genes in ECs. Comparing the expression profile of HBEC-5i cells cultured either in the presence of iRBCs or in the presence of niRBCs revealed significant upregulation of genes linked to immune response, nucleosome assembly, NF-kappa B signaling, angiogenesis, and antiviral immune response/interferon-alpha/beta signaling. Raising the temperature to 40°C, simulating fever, led to further upregulation of many genes, particularly those involved in cytokine production and angiogenesis. In summary, the presence of iRBCs stimulates ECs, activating several immunological pathways and affecting antiviral (-parasitic) mechanisms and angiogenesis. Our data uncovered the induction of the interferon-alpha/beta signaling pathway in ECs in response to iRBCs.

Differences in cell subsets between sun-exposed and unexposed skin: preliminary single-cell sequencing and biological analysis from a single case

Introduction

The composition and subsets of skin cells continuously change in a dynamic manner. However, the specific microcosmic alterations of human photoaged skin, independent of chronologic aging, remain unclear and have been infrequently analyzed. This study aimed to evaluate the biological processes and mechanisms underlying cell-subgroup alterations in skin photoaging.

Methods

We utilized single-cell sequencing and biological analysis from a single case to investigate the effects of photoaging. Skin punch biopsies were taken from sun-exposed forearm skin and unexposed buttock skin from the same individual for comparative analysis.

Results

Our analysis identified 25 cell clusters and 12 skin cell types, revealing significant changes in unique gene expressions between the sun-exposed and unexposed skin samples. A comparison of cell numbers within each cluster revealed 9 dominant cell clusters in sun-exposed skin and 16 dominant cell clusters in unexposed skin. Enrichment analysis indicated that PD-L1 expression and the PD-1 checkpoint pathway were more prominent in sun-exposed skin, while MAPK, TNF-alpha, TGF-beta, and apoptosis pathways were more enriched in hair follicle cells of sun-exposed skin.

Discussion

This study reveals changes in cell components in photoaged skin from a single case and provides novel insights into cellular subpopulations and pathology during repeated UVA-induced skin damage. These findings enhance our understanding of the complex interplay between different cells in photoaged skin and offer potential targets for preventing human skin photoaging and UV-induced skin cancers.

Restriction factors regulating human herpesvirus infections

Herpesviruses are DNA viruses and the cause of diseases ranging from mild skin conditions to severe brain diseases. Mammalian antiviral host defense comprises an array of mechanisms, including restriction factors (RFs), which block specific steps in viral replication cycles. In recent years, knowledge of RFs that contribute to controlling herpesvirus infections has expanded significantly, along with a new understanding of viral evasion mechanisms and disease pathogenesis. By integrating findings from human genetics, murine models, and cellular studies, this review provides a current view of RF control of herpesvirus infections. We also explore the regulation of RF expression, discuss the roles of RFs in diseases, and point towards their growing potential as candidate therapeutic targets.

Quantitative Proteomic Analysis of Macrophages Infected with Trypanosoma cruzi Reveals Different Responses Dependent on the SLAMF1 Receptor and the Parasite Strain

Chagas disease is caused by the intracellular protozoan parasite Trypanosoma cruzi. This disease affects mainly rural areas in Central and South America, where the insect vector is endemic. However, this disease has become a world health problem since migration has spread it to other continents. It is a complex disease with many reservoirs and vectors and high genetic variability. One of the host proteins involved in the pathogenesis is SLAMF1. This immune receptor acts during the infection of macrophages controlling parasite replication and thus affecting survival in mice but in a parasite strain-dependent manner. Therefore, we studied the role of SLAMF1 by quantitative proteomics in a macrophage in vitro infection and the different responses between Y and VFRA strains of Trypanosoma cruzi. We detected different significant up- or downregulated proteins involved in immune regulation processes, which are SLAMF1 and/or strain-dependent. Furthermore, independently of SLAMF1, this parasite induces different responses in macrophages to counteract the infection and kill the parasite, such as type I and II IFN responses, NLRP3 inflammasome activation, IL-18 production, TLR7 and TLR9 activation specifically with the Y strain, and IL-11 signaling specifically with the VFRA strain. These results have opened new research fields to elucidate the concrete role of SLAMF1 and discover new potential therapeutic approaches for Chagas disease.

Unveiling heterogeneity in MSCs: exploring marker-based strategies for defining MSC subpopulations

Mesenchymal stem/stromal cells (MSCs) represent a heterogeneous cell population distributed throughout various tissues, demonstrating remarkable adaptability to microenvironmental cues and holding immense promise for disease treatment. However, the inherent diversity within MSCs often leads to variability in therapeutic outcomes, posing challenges for clinical applications. To address this heterogeneity, purification of MSC subpopulations through marker-based isolation has emerged as a promising approach to ensure consistent therapeutic efficacy. In this review, we discussed the reported markers of MSCs, encompassing those developed through candidate marker strategies and high-throughput approaches, with the aim of explore viable strategies for addressing the heterogeneity of MSCs and illuminate prospective research directions in this field.

Autophagy-related protein 5 (ATG5) interacts with bone marrow stromal cell antigen 2 (BST2) to stimulate HBV replication through antagonizing the antiviral activity of BST2

Hepatitis B virus (HBV) infection is a major global health burden with 820 000 deaths per year. In our previous study, we found that the knockdown of autophagy-related protein 5 (ATG5) significantly upregulated the interferon-stimulated genes (ISGs) expression to exert the anti-HCV effect. However, the regulation of ATG5 on HBV replication and its underlying mechanism remains unclear. In this study, we screened the altered expression of type I interferon (IFN-I) pathway genes using RT² Profiler™ PCR array following ATG5 knock-down and we found the bone marrow stromal cell antigen 2 (BST2) expression was significantly increased. We then verified the upregulation of BST2 by ATG5 knockdown using RT-qPCR and found that the knockdown of ATG5 activated the Janus kinase/signal transducer and activator of transcription (JAK-STAT) signaling pathway. ATG5 knockdown or BST2 overexpression decreased Hepatitis B core Antigen (HBcAg) protein, HBV DNA levels in cells and supernatants of HepAD38 and HBV-infected NTCP-HepG2. Knockdown of BST2 abrogated the anti-HBV effect of ATG5 knockdown. Furthermore, we found that ATG5 interacted with BST2, and further formed a ternary complex together with HBV-X (HBx). In conclusion, our finding indicates that ATG5 promotes HBV replication through decreasing BST2 expression and interacting with it directly to antagonize its antiviral function.

Molecular biology of canine parainfluenza virus V protein and its potential applications in tumor immunotherapy

Canine parainfluenza virus (CPIV) is a zoonotic virus that is widely distributed and is the main pathogen causing canine infectious respiratory disease (CIRD), also known as "kennel cough," in dogs. The CPIV-V protein is the only nonstructural protein of the virus and plays an important role in multiple stages of the virus life cycle by inhibiting apoptosis, altering the host cell cycle and interfering with the interferon response. In addition, studies have shown that the V protein has potential applications in the field of immunotherapy in oncolytic virus therapy or self-amplifying RNA vaccines. In this review, the biosynthesis, structural characteristics and functions of the CPIV-V protein are reviewed with an emphasis on how it facilitates viral immune escape and its potential applications in the field of immunotherapy. Therefore, this review provides a scientific basis for research into the CPIV-V protein and its potential applications.

Human BST2 inhibits rabies virus release independently of cysteine-linked dimerization and asparagine-linked glycosylation

The innate immune response is a first-line defense mechanism triggered by rabies virus (RABV). Interferon (IFN) signaling and ISG products have been shown to confer resistance to RABV at various stages of the virus's life cycle. Human tetherin, also known as bone marrow stromal cell antigen 2 (hBST2), is a multifunctional transmembrane glycoprotein induced by IFN that has been shown to effectively counteract many viruses through diverse mechanisms. Here, we demonstrate that hBST2 inhibits RABV budding by tethering new virions to the cell surface. It was observed that release of virus-like particles (VLPs) formed by RABV G (RABV-G VLPs), but not RABV M (RABV-G VLPs), were suppressed by hBST2, indicating that RABV-G has a specific effect on the hBST2-mediated restriction of RABV. The ability of hBST2 to prevent the release of RABV-G VLPs and impede RABV growth kinetics is retained even when hBST2 has mutations at dimerization and/or glycosylation sites, making hBST2 an antagonist to RABV, with multiple mechanisms possibly contributing to the hBST2-mediated suppression of RABV. Our findings expand the knowledge of host antiviral mechanisms that control RABV infection.

BST2 negatively regulates porcine reproductive and respiratory syndrome virus replication by restricting the expression of viral proteins

Porcine reproductive and respiratory syndrome virus (PRRSV) has seriously affected the viability of swine industries worldwide, and effective measures to control PRRSV are urgently required. Understanding the mechanisms of action of antiviral proteins is crucial for developing antiviral strategies. Interferon-induced bone marrow stromal cell antigen 2 (BST2) can inhibit the replication of various viruses via different pathways. However, little is known about the effects of BST2 on PRRSV. Therefore, this study aimed to evaluate whether the interferon-induced BST2 can inhibit PRRSV replication. We used western blotting and RT-qPCR techniques to analyze the effect of BST2 overexpression and knockdown on PRRSV replication. Overexpression of BST2 inhibited the replication of PRRSV, whereas knockdown of BST2 by small interfering RNA promoted PRRSV replication. Additionally, the expression of BST2 was upregulated during the early phase of PRRSV infection in porcine alveolar macrophages. Analysis of PRRSV proteins showed that BST2 restricted the expression of several non-structural viral proteins. BST2 downregulated the expression of Nsp12 through a proteasome-dependent pathway and downregulated the expression and transcription of E protein. These findings demonstrate the potential of BST2 as a critical regulator of PRRSV replication.

Detection of Antibody-Dependent Cell-Mediated Cytotoxicity-Supporting Antibodies by NK-92-CD16A Cell Externalization of CD107a: Recognition of Antibody Afucosylation and Assay Optimization

Antibody-dependent cell-mediated cytotoxicity (ADCC) by natural killer (NK) lymphocytes eliminates cells infected with viruses. Anti-viral ADCC requires three components: (1) antibody; (2) effector lymphocytes with the Fc-IgG receptor CD16A; and (3) viral proteins in infected cell membranes. Fc-afucosylated antibodies bind with greater affinity to CD16A than fucosylated antibodies; individuals' variation in afucosylation contributes to differences in ADCC. Current assays for afucosylated antibodies involve expensive methods. We report an improved bioassay for antibodies that supports ADCC, which encompasses afucosylation. This assay utilizes the externalization of CD107a by NK-92-CD16A cells after antibody recognition. We used anti-CD20 monoclonal antibodies, GA101 WT or glycoengineered (GE), 10% or ~50% afucosylated, and CD20-positive Raji target cells. CD107a increased detection 7-fold compared to flow cytometry to detect Raji-bound antibodies. WT and GE antibody effective concentrations (EC50s) for CD107a externalization differed by 20-fold, with afucosylated GA101-GE more detectable. The EC50s for CD107a externalization vs. 51Cr cell death were similar for NK-92-CD16A and blood NK cells. Notably, the % CD107a-positive cells were negatively correlated with dead Raji cells and were nearly undetectable at high NK:Raji ratios required for cytotoxicity. This bioassay is very sensitive and adaptable to assess anti-viral antibodies but unsuitable as a surrogate assay to monitor cell death after ADCC.

Interferon-induced restriction of Chikungunya virus infection

Chikungunya virus (CHIKV) is an enveloped RNA virus that causes Chikungunya fever (CHIKF), which is transmitted to humans through the bite of infected Aedes mosquitos. Although CHIKVF had been regarded as an endemic disease in limited regions of Africa and Asia, the recent global reemergence of CHIKV heightened awareness of this infectious disease, and CHIKV infection is currently considered an increasing threat to public health. However, no specific drug or licensed vaccine is available for CHIKV infection. As seen in other RNA virus infections, CHIKV triggers the interferon (IFN) response that plays a central role in host defense against pathogens. Experimental evidence has demonstrated that control of CHIVK replication by the IFN response is achieved by antiviral effector molecules called interferon-stimulated genes (ISGs), whose expressions are upregulated by IFN stimulation. This review details the molecular basis of the IFN-mediated suppression of CHIKV, particularly the ISGs restricting CHIKV replication.