Deletion of MyD88 in T Cells Improves Antitumor Activity in Melanoma.

Cytotoxic CD8+ T cells are central to the antitumor immune response by releasing cytotoxic granules that kill tumor cells. They are activated by antigen-presenting cells, which become activated by DAMPs (damage associated molecular patterns) through MyD88. However, the suppressive tumor microenvironment promotes T-cell tolerance to tumor antigens, in part by enhancing the activity of immune checkpoint molecules that prevent CD8+ T-cell activation and cytotoxicity. MyD88 limits CD4+ T-cell activation during cardiac adaptation to stress. A similar mechanism is hypothesized to exist in CD8+ T cells that could be modulated to improve antitumor immunity. Herein, adoptive transfer of MyD88-/- CD8+ T cells in melanoma-bearing T-cell-deficient mice resulted in slower tumor growth, greater intratumoral T-cell accumulation, and higher melanoma cell death compared with transfer of wild-type CD8+ T cells. These findings were also observed in T-cell-specific MyD88-/- mice compared with wild-type littermates implanted with melanoma. Mechanistically, deletion of MyD88 enhanced CD8+ T-cell activation and survival, and T-cell receptor induced degranulation of cytotoxic molecules, overall improving the killing of melanoma cells. This enhanced cytotoxicity was retained in mice bearing tumors expressing the specific antigen for which cytotoxic T-cells were restricted. This study's results demonstrate a conserved mechanism for MyD88 in modulating CD8+ T-cell activation and represent a novel target in improving cancer immunotherapy.

T-Cell MyD88 Is a Novel Regulator of Cardiac Fibrosis Through Modulation of T-Cell Activation.

BACKGROUND: Cardiac inflammation in heart failure is characterized by the presence of damage-associated molecular patterns, myeloid cells, and T cells. Cardiac damage-associated molecular patterns provide continuous proinflammatory signals to myeloid cells through TLRs (toll-like receptors) that converge onto the adaptor protein MyD88 (myeloid differentiation response 88). These induce activation into efficient antigen-presenting cells that activate T cells through their TCR (T-cell receptor). T-cell activation results in cardiotropism, cardiac fibroblast transformation, and maladaptive cardiac remodeling. T cells rely on TCR signaling for effector function and survival, and while they express MyD88 and damage-associated molecular pattern receptors, their role in T-cell activation and cardiac inflammation is unknown. METHODS: We performed transverse aortic constriction in mice lacking MyD88 in T cells and analyzed remodeling, systolic function, survival, and T-cell activation. We profiled wild type versus Myd88-/- mouse T cells at the transcript and protein level and performed several functional assays. RESULTS: Analysis of single-cell RNA-sequencing data sets revealed that MyD88 is expressed in mouse and human cardiac T cells. MyD88 deletion in T cells resulted in increased levels of cardiac T-cell infiltration and fibrosis in response to transverse aortic constriction. We discovered that TCR-activated Myd88-/- T cells had increased proinflammatory signaling at the transcript and protein level compared with wild type, resulting in increased T-cell effector functions such as adhesion, migration across endothelial cells, and activation of cardiac fibroblast. Mechanistically, we found that MyD88 modulates T-cell activation and survival through TCR-dependent rather than TLR-dependent signaling. CONCLUSIONS: Our results outline a novel intrinsic role for MyD88 in limiting T-cell activation that is central to tune down cardiac inflammation during cardiac adaptation to stress.

The IFITM proteins mediate cellular resistance to influenza A H1N1 virus, West Nile virus, and dengue virus.

Influenza viruses exploit host cell machinery to replicate, resulting in epidemics of respiratory illness. In turn, the host expresses antiviral restriction factors to defend against infection. To find host cell modifiers of influenza A H1N1 viral infection, we used a functional genomic screen and identified over 120 influenza A virus-dependency factors with roles in endosomal acidification, vesicular trafficking, mitochondrial metabolism, and RNA splicing. We discovered that the interferon-inducible transmembrane proteins IFITM1, 2, and 3 restrict an early step in influenza A viral replication. The IFITM proteins confer basal resistance to influenza A virus but are also inducible by interferons type I and II and are critical for interferon's virustatic actions. Further characterization revealed that the IFITM proteins inhibit the early replication of flaviviruses, including dengue virus and West Nile virus. Collectively this work identifies a family of antiviral restriction factors that mediate cellular innate immunity to at least three major human pathogens.

Management of patients with chronic rhinosinusitis with nasal polyps in Spain: learnings from a nationwide survey of otorhinolaryngologists.

PURPOSE: To describe the self-reported practices on the diagnosis, treatment, and follow-up of patients with chronic rhinosinusitis with nasal polyps (CRSwNP) by ear, nose, and throat (ENT) specialists in Spain to identify potential areas for management optimization. METHODS: A cross-sectional online survey with 16 questions was carried out. Recruitment was performed by emailing registered ENT specialists in the Spanish Society of Otorhinolaryngology and Head and Neck Surgery (SEORL-CCC). RESULTS: In total, 127 ENT specialists completed the survey. Fifty-one percent of respondents combined clinical criteria and objective evidence of mucosal inflammation to diagnose CRSwNP. Patient interview and, to a lower degree, a visual analogue scale were the most employed diagnostic tools to quantify symptom severity. Less than half (45%) routinely used the 22-item sino-nasal outcomes test (SNOT-22) to assess the impact of CRSwNP disease in quality of life. The use of patient-reported outcomes and other clinical evaluation tools showed a larger uptake among ENT specialists that worked at an ENT department with an available rhinology unit. Almost all the specialists surveyed (95%) recommended biological treatment, particularly in patients with uncontrolled CRSwNP with respiratory comorbidities (76%), as well as in candidates for revision surgery (66%). CONCLUSION: Spanish otorhinolaryngologists showed a trend toward incorporating CRSwNP guideline recommendations in their clinical practice. The observed low uptake of patient-reported outcomes and objective clinical evaluation tools in routine clinical practise have been identified as areas for optimizing the management of patients with CRSwNP.

Comparison of Glasgow Coma Scale Full Outline of UnResponsiveness and Glasgow Coma Scale: Pupils Score for Predicting Outcome in Patients with Traumatic Brain Injury.

Background: Glasgow coma scale (GCS) score is the most widely used clinical score for the initial assessment of neurologically injured patients and is also frequently used for prognostication. Other scores such as the Full Outline of UnResponsivness (FOUR) score and the Glasgow Coma Scale-Pupils (GCS-P) score have been more recently developed and are gaining popularity. This prospective cohort study was conducted to compare various scores in terms of their ability to predict outcomes at 3 months in patients with traumatic brain injury (TBI). Materials and methods: The study was carried out between October 2020 and March 2022. Patients who presented to the hospital with TBI were assessed for inclusion. Initial coma scores were assessed in the emergency department and again after 48 hours of admission. Outcome was assessed using the extended Glasgow outcome score (GOSE) at 3 months after injury. The receiver operating curve (ROC) was plotted to correlate coma scores with the outcome, and the area under the curve (AUC) was compared. Results: A total of 355 patients with TBI were assessed for eligibility, of which 204 patients were included in the study. The AUC values to predict poor outcomes for initial GCS, FOUR, and GCS-P scores were 0.75 each. The AUC values for 48-hour coma scores were 0.88, 0.87, and 0.88, respectively. Conclusion: The GCS, FOUR, and GCS-P scores were found to be comparable in predicting the functional outcome at 3 months as assessed by GOSE. However, coma scores assessed at 48 hours were better predictors of poor outcomes at 3 months than coma scores recorded initially at the time of hospital admission. How to cite this article: Chawnchhim AL, Mahajan C, Kapoor I, Sinha TP, Prabhakar H, Chaturvedi A. Comparison of Glasgow Coma Scale Full Outline of UnResponsiveness and Glasgow Coma Scale: Pupils Score for Predicting Outcome in Patients with Traumatic Brain Injury. Indian J Crit Care Med 2024;28(3):256-264.

A Modular Turn-On Strategy to Profile E2-Specific Ubiquitination Events in Living Cells.

A cascade of three enzymes, E1-E2-E3, is responsible for transferring ubiquitin to target proteins, which controls many different aspects of cellular signaling. The role of the E2 has been largely overlooked, despite influencing substrate identity, chain multiplicity, and topology. Here we report a method-targeted charging of ubiquitin to E2 (tCUbE)-that can track a tagged ubiquitin through its entire enzymatic cascade in living mammalian cells. We use this approach to reveal new targets whose ubiquitination depends on UbcH5a E2 activity. We demonstrate that tCUbE can be broadly applied to multiple E2s and in different human cell lines. tCUbE is uniquely suited to examine E2-E3-substrate cascades of interest and/or piece together previously unidentified cascades, thereby illuminating entire branches of the UPS and providing critical insight that will be useful for identifying new therapeutic targets in the UPS.

Dysfunctional HIV-specific CD8+ T cell proliferation is associated with increased caspase-8 activity and mediated by necroptosis.

Decreased HIV-specific CD8(+) T cell proliferation is a hallmark of chronic infection, but the mechanisms of decline are unclear. We analyzed gene expression profiles from antigen-stimulated HIV-specific CD8(+) T cells from patients with controlled and uncontrolled infection and identified caspase-8 as a correlate of dysfunctional CD8(+) T cell proliferation. Caspase-8 activity was upregulated in HIV-specific CD8(+) T cells from progressors and correlated positively with disease progression and programmed cell death-1 (PD-1) expression, but negatively with proliferation. In addition, progressor cells displayed a decreased ability to upregulate membrane-associated caspase-8 activity and increased necrotic cell death following antigenic stimulation, implicating the programmed cell death pathway necroptosis. In vitro necroptosis blockade rescued HIV-specific CD8(+) T cell proliferation in progressors, as did silencing of necroptosis mediator RIPK3. Thus, chronic stimulation leading to upregulated caspase-8 activity contributes to dysfunctional HIV-specific CD8(+) T cell proliferation through activation of necroptosis and increased cell death.

Impact of osteoarthritis disease severity on treatment patterns and healthcare resource use: analysis of real-world data.

OBJECTIVE: To understand treatment patterns and healthcare resource utilization (HCRU) related to osteoarthritis (OA) disease severity in patients in five European countries. METHOD: Data were drawn from the Adelphi OA Disease Specific Programme™ (2017-18). Physicians classified their patients as having mild, moderate, or severe OA, and provided details on their current prescribed therapy and HCRU, including healthcare professional (HCP) consultations, diagnostics and testing, and hospitalizations. Comparisons between disease severity groups were made using analysis of variance and chi-squared tests. RESULTS: The study included 489 physicians (primary care physicians, rheumatologists, orthopaedic surgeons) reporting on 3596 OA patients: 24% mild, 53% moderate, and 23% severe disease. Both physicians and patients reported decreasing satisfaction with treatment with greater disease severity, despite the number of classes of prescribed drugs and increased use of opioids, which were used in almost half of patients with severe OA. For patients whose treatment was not effective, physicians prescribed the same therapeutic options, which were cycled in subsequent treatment lines, with multiple treatment regimens being commonly used. Patients with greater symptom severity also had more physician consultations, while the numbers of tests/imaging, predominantly X-rays, conducted to diagnose or monitor OA increased significantly with disease severity. The type of HCP involvement in patient management also varied by OA severity. CONCLUSIONS: Across five European countries, the use of both non-pharmacological and pharmacological treatments increases with greater disease severity. Those with more severe disease place a greater demand on healthcare resources, with HCP consultations, tests, and hospital visits increasing with severity.

Maskless Fourier transform holography.

Fourier transform holography is a lensless imaging technique that retrieves an object's exit-wave function with high fidelity. It has been used to study nanoscale phenomena and spatio-temporal dynamics in solids, with sensitivity to the phase component of electronic and magnetic textures. However, the method requires an invasive and labor-intensive nanopatterning of a holography mask directly onto the sample, which can alter the sample properties, forces a fixed field-of-view, and leads to a low signal-to-noise ratio at high resolution. In this work, we propose using wavefront-shaping diffractive optics to create a structured probe with full control of its phase at the sample plane, circumventing the need for a mask. We demonstrate in silico that the method can image nanostructures and magnetic textures and validate our approach with a visible light-based experiment. The method enables investigation of a plethora of phenomena at the nanoscale including magnetic and electronic phase coexistence in solids, with further uses in soft and biological matter research.

Frizzled proteins are colonic epithelial receptors for C. difficile toxin B.

Clostridium difficile toxin B (TcdB) is a critical virulence factor that causes diseases associated with C. difficile infection. Here we carried out CRISPR-Cas9-mediated genome-wide screens and identified the members of the Wnt receptor frizzled family (FZDs) as TcdB receptors. TcdB binds to the conserved Wnt-binding site known as the cysteine-rich domain (CRD), with the highest affinity towards FZD1, 2 and 7. TcdB competes with Wnt for binding to FZDs, and its binding blocks Wnt signalling. FZD1/2/7 triple-knockout cells are highly resistant to TcdB, and recombinant FZD2-CRD prevented TcdB binding to the colonic epithelium. Colonic organoids cultured from FZD7-knockout mice, combined with knockdown of FZD1 and 2, showed increased resistance to TcdB. The colonic epithelium in FZD7-knockout mice was less susceptible to TcdB-induced tissue damage in vivo. These findings establish FZDs as physiologically relevant receptors for TcdB in the colonic epithelium.

Physician and patient perceptions of surgical procedures for osteoarthritis of the knee in the United States, Europe, and Japan: results of a real-world study.

BACKGROUND: Osteoarthritis (OA) is the most common form of arthritis, with the knee being the joint most frequently affected, and symptomatic knee OA affecting around one quarter of the general population. For patients who do not respond to non-pharmacologic or pharmacologic treatment, surgery is a recommended option. The objectives of this study were to compare the willingness of patients with knee OA to undergo surgery, together with reasons for delaying surgery, and factors affecting successful outcomes. METHODS: A point-in-time survey was conducted in 729 primary care physicians, rheumatologists, orthopedic surgeons, and 2,316 patients with knee OA across three geographical regions: Japan, the United States (US), and Europe (EUR: France, Spain, Italy, Germany, and the United Kingdom), in order to garner their perceptions of knee surgery. Regression models were used to identify factors that might affect patients' and physicians' perceptions of surgery, including severity of OA (mild/moderate/severe), number of affected joints, surgery status, and willingness to undergo or delay surgery. RESULTS: Baseline demographics were similar between US and EUR, although patients in Japan were more likely to be female, older, and only 7% in fulltime employment. We found that few patients with end-stage knee OA, across all regions, but particularly Japan, were willing to undergo surgery (Japan 17%, US 32%, EUR 38%), either through fear, or the lack of awareness of the risk/benefits. Moreover, surgeons are prepared to delay surgery in elderly or unwilling patients, due to their dissatisfaction with the outcome, and may defer surgery in younger patients due to the need for future revision. We also identified a disconnect between physicians, of whom over 80% consider improved functioning to be the most important outcome of surgery, and patients, who seek pain relief (Japan 60%, US 35%, EUR 14%). Since physicians across all regions considered pain reduction to be an indication of surgery success (Japan 27%, US 47%, EUR 43%), this may indicate a need for improved communication to patients on the potential benefits of surgery. CONCLUSION: Managing the expectations of patients undergoing surgery remains an important goal in the treatment of knee OA and may help guide physician choice.

OR14I1 is a receptor for the human cytomegalovirus pentameric complex and defines viral epithelial cell tropism.

A human cytomegalovirus (HCMV) pentameric glycoprotein complex (PC), gH-gL-UL128-UL130-UL131A, is necessary for viral infection of clinically relevant cell types, including epithelial cells, which are important for interhost transmission and disease. We performed genome-wide CRISPR/Cas9 screens of different cell types in parallel to identify host genes specifically required for HCMV infection of epithelial cells. This effort identified a multipass membrane protein, OR14I1, as a receptor for HCMV infection. This olfactory receptor family member is required for HCMV attachment, entry, and infection of epithelial cells and is dependent on the presence of viral PC. OR14I1 is required for AKT activation and mediates endocytosis entry of HCMV. We further found that HCMV infection of epithelial cells is blocked by a synthetic OR14I1 peptide and inhibitors of adenylate cyclase and protein kinase A (PKA) signaling. Identification of OR14I1 as a PC-dependent HCMV host receptor associated with epithelial tropism and the role of the adenylate cyclase/PKA/AKT-mediated signaling pathway in HCMV infection reveal previously unappreciated targets for the development of vaccines and antiviral therapies.

Adsorption of ciprofloxacin from aqueous solution using surface improved tamarind shell as an economical and effective adsorbent.

Antibiotics in water bodies are emerging as an alarming new pollutant because of its persistent and recombinant nature. In recent period of human lifestyle, pharmaceutical products play a vital role in many perspectives. Due to this unpredictable usage of products, the unreacted components release into waterbodies in trace quantities. Eventhough these trace quantities initiate a crisis of developing resistant antibacterial strains which pose health risks to humans and animals. This work reports the batch adsorption of a fluoroquinolone, a fourth-generation antibiotic compound by a biosorbent made by acid-treated tamarind shells. The shells were treated with zinc chloride and hydrochloric acid. The characterization of biosorbent was performed by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The optimized adsorption parameters of time, pH and temperature were 30 minutes, 6 and 60 °C. The adsorbent can be reused up to seven times with negligible loss in its adsorption capacity. Adsorption followed by Langmuir, Freundlich and Tempkin model where used to determine the correlation coefficient. Pseudo first-order, second-order and intra-particle kinetic model were used to fit the experimental data. The results are best described by pseudo second-order denoting chemisorption and Freundlich isotherm model describing multilayer adsorption.Novelty StatementThe proposed work is to investigate about improved tamarind shell as biomass used in the removal unreacted PPCP components that have been released into aquatic environment.The novelty of this paper lies in that it puts forward a better resource utilization method for treating PPCP component wastewater, and studies the method theoretically from the perspective of mechanism and proves its feasibility.Identifying the maximum adsorption of antibiotic component from wastewater under different conditions and finding the optimum range.In addition to the existing literatures, this study has compared the adsorption efficiency of raw and treated adsorbent material prepared using Tamarind shell.

Rhino-orbito-cerebral mucormycosis: patient characteristics in pre-COVID-19 and COVID-19 period.

BACKGROUND: Rhino-orbito-cerebral-mucormycosis (ROCM), a rare and potentially fatal disease was seen in increasing numbers during the COVID-19 pandemic. This study describes and compares the patient characteristics and outcomes in COVID-19 associated mucormycosis (CAM) and non-COVID-19 mucormycosis (non-CAM). METHODOLOGY: CAM patients (24 cases) were recruited from the COVID-19 period and non-CAM (24 controls) from the pre-COVID-19 period. Clinical data of the CAM group was collected retrospectively with 3 month outcomes prospectively. The non-CAM group data was collected retrospectively. Patient characteristics were compared and risk factors for mortality in ROCM were assessed. RESULTS: Orbital symptoms [altered vision, restricted eye movements, ptosis] and intracranial involvement were higher in CAM patients on presentation. Similarly, the radiological involvement of orbit (orbital apex, superior orbital fissure) and intracranial cavity (intracranial thrombosis, cavernous sinus) was also higher in CAM patients. Newly detected diabetes was found only in CAM patients (29.2%). Although univariate analysis suggested an increased mortality risk in ROCM patients with orbital involvement, the multivariate analysis showed no increased risk with any of the parameters assessed, including COVID-19 positivity. CONCLUSIONS: Compared to the non-CAM, the disease presentation was severe in CAM with higher frequency of orbital and intracranial involvement. However, with early detection and treatment, the short term survival was comparable in both groups.

Sonic application of one-step self-etch adhesive in composite restorations of non-carious cervical lesions: A double-blind randomized clinical trial.

OBJECTIVES: To evaluate the influence of the sonic device on the clinical performance of one-step self-etch adhesive systems in non-carious cervical lesions (NCCLs) after 18 months. MATERIALS AND METHODS: Forty patients participated in this study. Eighty restorations were assigned to two groups (n = 40): Sonic application and Manual application. After the adhesive application (iBond Self-Etch, Kulzer, Hanau, Germany), NCCLs were restored using composite resin (Charisma, Kulzer, Hanau, Germany). The restorations were evaluated at baseline and after 18 months both according to the Word Dental Federation (FDI) and the United States Public Health Service (USPHS) criteria. Friedman repeated measures analysis of variance by rank and Wilcoxon test for significance in each pair were applied (α = 0.05). RESULTS: After 18 months, 38 patients were evaluated. Twenty-three restorations were lost (19 for manual vs. 4 for sonic application). The retention rates (95% confidence interval) were 50% (CI 34.8%-65.1%) for manual application and 84.2% (CI 69.6%-92.6%) for sonic application (p < 0.05). Twelve restorations showed marginal staining (nine for manual vs. three for sonic application; FDI, p < 0.05) and nine some marginal discrepancy (seven for manual vs. two for sonic application; FDI, p < 0.05). No restorations showed postoperative sensitivity and caries recurrence at the time. CONCLUSION: The sonic application increases the retention rate of iBond Self-Etch after 18 months of clinical evaluation in NCCLs. CLINICAL RELEVANCE: The application of a simplified self-etch adhesive (iBond Self-Etch) associated to a sonic device seems to be an alternative to improve the clinical behavior in NCCLs.

MyD88: At the heart of inflammatory signaling and cardiovascular disease.

Cardiovascular disease is a leading cause of death worldwide and is associated with systemic inflammation. In depth study of the cell-specific signaling mechanisms mediating the inflammatory response is vital to improving anti-inflammatory therapies that reduce mortality and morbidity. Cellular damage in the cardiovascular system results in the release of damage associated molecular patterns (DAMPs), also known as "alarmins," which activate myeloid cells through the adaptor protein myeloid differentiation primary response 88 (MyD88). MyD88 is broadly expressed in most cell types of the immune and cardiovascular systems, and its role often differs in a cardiovascular disease context and cell specific manner. Herein we review what is known about MyD88 in the setting of a variety of cardiovascular diseases, discussing cell specific functions and the relative contributions of MyD88-dependent vs. independent alarmin triggered inflammatory signaling. The widespread involvement of these pathways in cardiovascular disease, and their largely unexplored complexity, sets the stage for future in depth mechanistic studies that may place MyD88 in both immune and non-immune cell types as an attractive target for therapeutic intervention in cardiovascular disease.

Genome-wide identification of Listeria monocytogenes CodY-binding sites.

CodY is a global transcriptional regulator that controls, directly or indirectly, the expression of dozens of genes and operons in Listeria monocytogenes. We used in vitro DNA affinity purification combined with massively parallel sequencing (IDAP-Seq) to identify genome-wide L. monocytogenes chromosomal DNA regions that CodY binds in vitro. The total number of CodY-binding regions exceeded 2,000, but they varied significantly in their strengths of binding at different CodY concentrations. The 388 strongest CodY-binding regions were chosen for further analysis. A strand-specific analysis of the data allowed pinpointing CodY-binding sites at close to single-nucleotide resolution. Gel shift and DNase I footprinting assays confirmed the presence and locations of several CodY-binding sites. Surprisingly, most of the sites were located within genes' coding regions. The binding site within the beginning of the coding sequence of the prfA gene, which encodes the master regulator of virulence genes, has been previously implicated in regulation of prfA, but this site was weaker in vitro than hundreds of other sites. The L. monocytogenes CodY protein was functionally similar to Bacillus subtilis CodY when expressed in B. subtilis cells. Based on the sequences of the CodY-binding sites, a model of CodY interaction with DNA is proposed.

Interferon-induced transmembrane protein 3 blocks fusion of sensitive but not resistant viruses by partitioning into virus-carrying endosomes.

Late endosome-resident interferon-induced transmembrane protein 3 (IFITM3) inhibits fusion of diverse viruses, including Influenza A virus (IAV), by a poorly understood mechanism. Despite the broad antiviral activity of IFITM3, viruses like Lassa virus (LASV), are fully resistant to its inhibitory effects. It is currently unclear whether resistance arises from a highly efficient fusion machinery that is capable of overcoming IFITM3 restriction or the ability to enter from cellular sites devoid of this factor. Here, we constructed and validated a functional IFITM3 tagged with EGFP or other fluorescent proteins. This breakthrough allowed live cell imaging of virus co-trafficking and fusion with endosomal compartments in cells expressing fluorescent IFITM3. Three-color single virus and endosome tracking revealed that sensitive (IAV), but not resistant (LASV), viruses become trapped within IFITM3-positive endosomes where they underwent hemifusion but failed to release their content into the cytoplasm. IAV fusion with IFITM3-containing compartments could be rescued by amphotericin B treatment, which has been previously shown to antagonize the antiviral activity of this protein. By comparison, virtually all LASV particles trafficked and fused with endosomes lacking detectable levels of fluorescent IFITM3, implying that this virus escapes restriction by utilizing endocytic pathways that are distinct from the IAV entry pathways. The importance of virus uptake and transport pathways is further reinforced by the observation that LASV glycoprotein-mediated cell-cell fusion is inhibited by IFITM3 and other members of the IFITM family expressed in target cells. Together, our results strongly support a model according to which IFITM3 accumulation at the sites of virus fusion is a prerequisite for its antiviral activity and that this protein traps viral fusion at a hemifusion stage by preventing the formation of fusion pores. We conclude that the ability to utilize alternative endocytic pathways for entry confers IFITM3-resistance to otherwise sensitive viruses.

Frequent Loss of IRF2 in Cancers Leads to Immune Evasion through Decreased MHC Class I Antigen Presentation and Increased PD-L1 Expression.

To arise and progress, cancers need to evade immune elimination. Consequently, progressing tumors are often MHC class I (MHC-I) low and express immune inhibitory molecules, such as PD-L1, which allows them to avoid the main antitumor host defense, CD8+ T cells. The molecular mechanisms that led to these alterations were incompletely understood. In this study, we identify loss of the transcription factor IRF2 as a frequent underlying mechanism that leads to a tumor immune evasion phenotype in both humans and mice. We identified IRF2 in a CRISPR-based forward genetic screen for genes that controlled MHC-I Ag presentation in HeLa cells. We then found that many primary human cancers, including lung, colon, breast, prostate, and others, frequently downregulated IRF2. Although IRF2 is generally known as a transcriptional repressor, we found that it was a transcriptional activator of many key components of the MHC-I pathway, including immunoproteasomes, TAP, and ERAP1, whose transcriptional control was previously poorly understood. Upon loss of IRF2, cytosol-to-endoplasmic reticulum peptide transport and N-terminal peptide trimming become rate limiting for Ag presentation. In addition, we found that IRF2 is a repressor of PD-L1. Thus, by downregulating a single nonessential gene, tumors become harder to see (reduced Ag presentation), more inhibitory (increased checkpoint inhibitor), and less susceptible to being killed by CD8+ T cells. Importantly, we found that the loss of Ag presentation caused by IRF2 downregulation could be reversed by IFN-stimulated induction of the transcription factor IRF1. The implication of these findings for tumor progression and immunotherapy are discussed.