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An influenza pandemic can occur when an influenza A virus with gene segments derived in part or whole from animal viruses becomes able to efficiently and sustainably transmit among humans [...]

The emergence of SARS-CoV-2 variants is jeopardizing the effectiveness of current vaccines and limiting the application of monoclonal antibody-based therapy for COVID-19 (refs. .sup.1,2). Here we analysed the memory B cells of five naive and five convalescent people vaccinated with the BNT162b2 mRNA vaccine to investigate the nature of the B cell and antibody response at the single-cell level. Almost 6,000 cells were sorted, over 3,000 cells produced monoclonal antibodies against the spike protein and more than 400 cells neutralized the original SARS-CoV-2 virus first identified in Wuhan, China. The B.1.351 (Beta) and B.1.1.248 (Gamma) variants escaped almost 70% of these antibodies, while a much smaller portion was impacted by the B.1.1.7 (Alpha) and B.1.617.2 (Delta) variants. The overall loss of neutralization was always significantly higher in the antibodies from naive people. In part, this was due to the IGHV2-5;IGHJ4-1 germline, which was found only in people who were convalescent and generated potent and broadly neutralizing antibodies. Our data suggest that people who are seropositive following infection or primary vaccination will produce antibodies with increased potency and breadth and will be able to better control emerging SARS-CoV-2 variants. Single-cell-level analysis of memory B cells and their response to vaccination against all SARS-CoV-2 variants of concern in individuals who either had or had not been previously exposed to the virus., Author(s): Emanuele Andreano [sup.1] , Ida Paciello [sup.1] , Giulia Piccini [sup.2] , Noemi Manganaro [sup.1] , Piero Pileri [sup.1] , Inesa Hyseni [sup.2] [sup.3] , Margherita Leonardi [sup.2] [sup.3] [...]

Lysosomal inhibition elicited by palmitoyl-protein thioesterase 1 (PPT1) inhibitors such as DC661 can produce cell death, but the mechanism for this is not completely understood. Programmed cell death pathways (autophagy, apoptosis, necroptosis, ferroptosis, and pyroptosis) were not required to achieve the cytotoxic effect of DC661. Inhibition of cathepsins, or iron or calcium chelation, did not rescue DC661-induced cytotoxicity. PPT1 inhibition induced lysosomal lipid peroxidation (LLP), which led to lysosomal membrane permeabilization and cell death that could be reversed by the antioxidant N-acetylcysteine (NAC) but not by other lipid peroxidation antioxidants. The lysosomal cysteine transporter MFSD12 was required for intralysosomal transport of NAC and rescue of LLP. PPT1 inhibition produced cell-intrinsic immunogenicity with surface expression of calreticulin that could only be reversed with NAC. DC661-treated cells primed naive T cells and enhanced T cell-mediated toxicity. Mice vaccinated with DC661-treated cells engendered adaptive immunity and tumor rejection in 'immune hot' tumors but not in 'immune cold' tumors. These findings demonstrate that LLP drives lysosomal cell death, a unique immunogenic form of cell death, pointing the way to rational combinations of immunotherapy and lysosomal inhibition that can be tested in clinical trials., Introduction With encouraging activity in clinical trials that involve the lysosomal inhibitor hydroxychloroquine (HCQ) (1), the identification of palmitoyl-protein thioesterase 1 (PPT1) as the molecular target of chloroquine derivatives (2), [...]

T follicular helper (T.sub.FH) cells are crucial for B cell-mediated humoral immunity.sup.1. Although transcription factors such as BCL6 drive the differentiation of T.sub.FH cells.sup.2,3, it is unclear whether and how post-transcriptional and metabolic programs enforce T.sub.FH cell programming. Here we show that the cytidine diphosphate (CDP)-ethanolamine pathway co-ordinates the expression and localization of CXCR5 with the responses of T.sub.FH cells and humoral immunity. Using in vivo CRISPR-Cas9 screening and functional validation in mice, we identify ETNK1, PCYT2, and SELENOI--enzymes in the CDP-ethanolamine pathway for de novo synthesis of phosphatidylethanolamine (PE)--as selective post-transcriptional regulators of T.sub.FH cell differentiation that act by promoting the surface expression and functional effects of CXCR5. T.sub.FH cells exhibit unique lipid metabolic programs and PE is distributed to the outer layer of the plasma membrane, where it colocalizes with CXCR5. De novo synthesis of PE through the CDP-ethanolamine pathway co-ordinates these events to prevent the internalization and degradation of CXCR5. Genetic deletion of Pcyt2, but not of Pcyt1a (which mediates the CDP-choline pathway), in activated T cells impairs the differentiation of T.sub.FH cells, and this is associated with reduced humoral immune responses. Surface levels of PE and CXCR5 expression on B cells also depend on Pcyt2. Our results reveal that phospholipid metabolism orchestrates post-transcriptional mechanisms for T.sub.FH cell differentiation and humoral immunity, highlighting the metabolic control of context-dependent immune signalling and effector programs. Enzymes in the cytidine diphosphate-ethanolamine metabolic pathway, which promotes de novo synthesis of phosphatidylethanolamine, are shown to act as post-transcriptional mediators of the differentiation of T follicular helper (T.sub.FH) cells, by regulating the chemokine receptor CXCR5., Author(s): Guotong Fu [sup.1] , Clifford S. Guy [sup.1] , Nicole M. Chapman [sup.1] , Gustavo Palacios [sup.1] , Jun Wei [sup.1] , Peipei Zhou [sup.1] , Lingyun Long [sup.1] [...]

Nucleotide-binding domain, leucine-rich repeat receptors (NLRs) mediate innate immunity by forming inflammasomes. Activation of the NLR protein NLRP1 requires autocleavage within its function-to-find domain (FIIND).sup.1-7. In resting cells, the dipeptidyl peptidases DPP8 and DPP9 interact with the FIIND of NLRP1 and suppress spontaneous NLRP1 activation.sup.8,9; however, the mechanisms through which this occurs remain unknown. Here we present structural and biochemical evidence that full-length rat NLRP1 (rNLRP1) and rat DPP9 (rDPP9) form a 2:1 complex that contains an autoinhibited rNLRP1 molecule and an active UPA-CARD fragment of rNLRP1. The ZU5 domain is required not only for autoinhibition of rNLRP1 but also for assembly of the 2:1 complex. Formation of the complex prevents UPA-mediated higher-order oligomerization of UPA-CARD fragments and strengthens ZU5-mediated NLRP1 autoinhibition. Structure-guided biochemical and functional assays show that both NLRP1 binding and enzymatic activity are required for DPP9 to suppress NLRP1 in human cells. Together, our data reveal the mechanism of DPP9-mediated inhibition of NLRP1 and shed light on the activation of the NLRP1 inflammasome. The 2:1 complex between the inflammatory mediator NLRP1 and the dipeptidyl peptidase DPP9 functions to sequester an inflammasome-forming fragment of NLRP1 and enhance NLRP1 autoinhibition., Author(s): Menghang Huang [sup.1] , Xiaoxiao Zhang [sup.1] , Gee Ann Toh [sup.2] , Qin Gong [sup.3] , Jia Wang [sup.1] , Zhifu Han [sup.1] , Bin Wu [sup.3] [sup.4] [...]

Most ovarian cancers are infiltrated by prognostically relevant activated T cells.sup.1-3, yet exhibit low response rates to immune checkpoint inhibitors.sup.4. Memory B cell and plasma cell infiltrates have previously been associated with better outcomes in ovarian cancer.sup.5,6, but the nature and functional relevance of these responses are controversial. Here, using 3 independent cohorts that in total comprise 534 patients with high-grade serous ovarian cancer, we show that robust, protective humoral responses are dominated by the production of polyclonal IgA, which binds to polymeric IgA receptors that are universally expressed on ovarian cancer cells. Notably, tumour B-cell-derived IgA redirects myeloid cells against extracellular oncogenic drivers, which causes tumour cell death. In addition, IgA transcytosis through malignant epithelial cells elicits transcriptional changes that antagonize the RAS pathway and sensitize tumour cells to cytolytic killing by T cells, which also contributes to hindering malignant progression. Thus, tumour-antigen-specific and -antigen-independent IgA responses antagonize the growth of ovarian cancer by governing coordinated tumour cell, T cell and B cell responses. These findings provide a platform for identifying targets that are spontaneously recognized by intratumoural B-cell-derived antibodies, and suggest that immunotherapies that augment B cell responses may be more effective than approaches that focus on T cells, particularly for malignancies that are resistant to checkpoint inhibitors. In patients with high-grade serous ovarian cancer, robust and protective humoral responses are dominated by B-cell-derived polyclonal IgA that binds to polymeric IgA receptors that are universally expressed on ovarian cancer cells., Author(s): Subir Biswas [sup.1] , Gunjan Mandal [sup.1] , Kyle K. Payne [sup.1] , Carmen M. Anadon [sup.1] , Chandler D. Gatenbee [sup.2] , Ricardo A. Chaurio [sup.1] , Tara [...]

The emergence of the novel henipavirus, Langya virus, received global attention after the virus sickened over three dozen people in China. There is heightened concern that henipaviruses, as respiratory pathogens, could spark another pandemic, most notably the deadly Nipah virus (NiV). NiV causes near-annual outbreaks in Bangladesh and India and induces a highly fatal respiratory disease and encephalitis in humans. No licensed countermeasures against this pathogen exist. An ideal NiV vaccine would confer both fast-acting and long-lived protection. Recently, we reported the generation of a recombinant vesicular stomatitis virus-based (rVSV-based) vaccine expressing the NiV glycoprotein (rVSV-[DELTA]G-[NiV.sub.B]G) that protected 100% of nonhuman primates from NiV-associated lethality within a week. Here, to evaluate the durability of rVSV-[DELTA]G- [NiV.sub.B]G, we vaccinated African green monkeys (AGMs) one year before challenge with an uniformly lethal dose of NiV. The rVSV- [DELTA]G-[NiV.sub.B]G vaccine induced stable and robust humoral responses, whereas cellular responses were modest. All immunized AGMs (whether receiving a single dose or prime-boosted) survived with no detectable clinical signs or NiV replication. Transcriptomic analyses indicated that adaptive immune signatures correlated with vaccine-mediated protection. While vaccines for certain respiratory infections (e.g., COVID-19) have yet to provide durable protection, our results suggest that rVSV-[DELTA]G- [NiV.sub.B]G elicits long-lasting immunity., Introduction Nipah virus (NiV) causes encephalitis and severe respiratory disease in humans with case-fatality rates (CFRs) ranging from 40% to 100% (1). Inherent features of NiV engender concern that the [...]

Milk contains bioactive molecules with important functions as defensive proteins; among them are the whey protein lactoferrin and proteins of the milk fat globule membrane (MFGM) present in buttermilk. The aim of this study has been to investigate the effects of lactoferrin, whey, and buttermilk as modulators of intestinal innate immunity and oxidative stress on intestinal epithelial cells, to evaluate its potential use for the development of functional foods. The mRNA expression levels of innate immune system Toll-like receptors (TLR2, TLR4, and TLR9), lipid peroxidation (malondialdehyde + 4-hydroxyalkenals) and protein expression levels of carbonyl were analyzed in enterocyte-like Caco-2/TC7 cells treated for 24 h with different concentrations of lactoferrin, whey, or buttermilk. None of the substances analyzed caused oxidative damage; however, whey significantly decreased the levels of lipid peroxidation. Furthermore, both lactoferrin and whey reduced the oxidative stress induced by lipopolysaccharide. With respect to TLR receptors, lactoferrin, whey, and buttermilk specifically altered the expression of TLR2, TLR4, and TLR9 receptors, with a strong decrease in the expression levels of TLR4. These results suggest that lactoferrin, whey, and buttermilk are potentially interesting ingredients for functional foods because they seem to modulate oxidative stress and the inflammatory response induced by the activation of TLRs. Key words: intestine, oxidative stress, TLR2, TLR4, TLR9. Le lait contient des molecules actives possedant d'importantes proprietes fonctionnelles comme proteines de defense; parmi elles se trouvent la lactoferrine du lactoserum et les proteines de la membrane du globule gras du lait (MFGM) presentes dans le lactoserum. L'objectif de cette etude consistait a examiner l'effet de la lactoferrine, du lactoserum et du babeurre en tant que modulateurs de l'immunite innee intestinale et du stress oxydant sur les cellules epitheliales intestinales, afin d'evaluer leur utilisation potentielle dans l'elaboration d'aliments fonctionnels. L'expression de l'ARNm des recepteurs de type Toll de l'immunite innee (TLR2, TLR4 et TLR9), la peroxydation lipidique (MDA et 4-HDA) et les niveaux de carbonyles de proteines ont ete analyses dans les cellules de type enterocytaire Caco-2/TC7 traitees pendant 24 heures avec differentes concentrations de lactoferrine, de lactoserum ou de babeurre. Aucune des substances analysees ne provoquait de dommage oxydant, toutefois, le lactoserum diminuait significativement les niveaux de peroxydation lipidique. De plus, la lactoferrine et le lactoserum etaient tous deux capables de reduire le stress oxydant induit par les lipopolysaccharides. En ce qui concerne les recepteurs TLR, la lactoferrine, le lactoserum et le babeurre modifiaient significativement l'expression de TLR2, TLR4 et TLR9, avec une forte diminution de l'expression de TLR4. Ces resultats suggerent que la lactoferrine, le lactoserum et le babeurre pourraient etre des ingredients potentiels interessants des aliments fonctionnels, car ils semblent moduler le stress oxydant et la reponse inflammatoire induite par l'activation des TLR. [Traduit par la Redaction] Mots-cles : intestin, stress oxydant, TLR2, TLR4, TLR9., Introduction Bovine milk is the most consumed type of milk, and several other dairy products have also been produced and consumed worldwide for millennia. Evidence from recent studies, system atic [...]

Lactoferrin is a multifunctional protein found in the secretions of mammals. The antimicrobial activity of lactoferrin was the first to be discovered and was assumed to be solely dependent on its iron-chelating ability. However, lactoferrin has been reported to display proteolytic activity towards bacterial virulence factors and to modulate the host defence by stimulating the immune system and balancing pathogen-induced inflammation. Here, we review the current understandings of the antimicrobial effect, interaction with host cells, and innate immune modulation of lactoferrin, and put forward this moonlighting protein as a possible alternative for antibiotics. Key words: lactoferrin, antimicrobial, proteolytic activity, immunomodulation. La lactoferrine est une proteine multifonctionnelle presente dans les secretions des mammiferes. L'activite antimicrobienne de la lactoferrine a ete la premiere a etre decouverte et on a presume qu'elle dependait uniquement de sa capacite a chelater le fer. Cependant, il s'est avere que la lactoferrine presentait une activite proteolytique envers des facteurs de virulence bacteriens et qu'elle modulait la defense de l'hote en stimulant le systeme immunitaire et en equilibrant l'inflammation induite par les agents pathogenes. Les auteurs font ici la synthese des connaissances actuelles sur l'effet antimicrobien, l'interaction avec les cellules de l'hote et la modulation immunitaire innee de la lactoferrine, et presentent cette proteine aux activites secondaires multiples comme solution de rechange possible aux antibiotiques. [Traduit par la Redaction] Mots-cles : lactoferrine, antimicrobien, activite proteolytique, immunomodulation., Introduction The discovery and development of antibiotics has greatly reduced morbidity and mortality from bacterial infections. However, extensive use and even misuse of these antibiotics in medicine and in agriculture [...]

T cell immunoglobulin mucin domain-containing protein 3 (Tim-3) negatively regulates innate and adaptive immunity in cancer. To identify the mechanisms of Tim-3 in cancer immunity, we evaluated the effects of Tim-3 blockade in human and mouse melanoma. Here, we show that human programmed cell death 1-positive ([PD-1.sup.+]) [Tim-3.sup.+][CD8.sup.+] tumor-infiltrating lymphocytes (TILs) upregulate phosphatidylserine (PS), a receptor for Tim-3, and acquire cell surface myeloid markers from antigen-presenting cells (APCs) through transfer of membrane fragments called trogocytosis. Tim-3 blockade acted on [Tim-3.sup.+] APCs in a PS-dependent fashion to disrupt the trogocytosis of activated tumor antigen-specific [CD8.sup.+] T cells and [PD-1.sup.+][Tim-3.sup.+] [CD8.sup.+] TILs isolated from patients with melanoma. Tim-3 and PD-1 blockades cooperated to disrupt trogocytosis of [CD8.sup.+] TILs in 2 melanoma mouse models, decreasing tumor burden and prolonging survival. Deleting Tim-3 in dendritic cells but not in [CD8.sup.+] T cells impeded the trogocytosis of [CD8.sup.+] TILs in vivo. Trogocytosed [CD8.sup.+] T cells presented tumor peptide-major histocompatibility complexes and became the target of fratricide T cell killing, which was reversed by Tim-3 blockade. Our findings have uncovered a mechanism Tim-3 uses to limit antitumor immunity., Introduction During chronic viral infection and cancer, tumor antigen-specific (TA-specific) [CD8.sup.+] T cells become dysfunctional and upregulate multiple inhibitory receptors, including programmed cell death 1/programmed death ligand 1 (PD-1/PD-L1) and [...]

IFN-[gamma]-stimulated MHC class I (MHC-I) antigen presentation underlies the core of antitumor immunity. However, sustained IFN-[gamma] signaling also enhances the programmed death ligand 1 (PD-L1) checkpoint pathway to dampen antitumor immunity. It remains unclear how these opposing effects of IFN-[gamma] are regulated. Here, we report that loss of the histone dimethyltransferase WHSC1 impaired the antitumor effect of IFN-[gamma] signaling by transcriptional downregulation of the MHC-I machinery without affecting PD-L1 expression in colorectal cancer (CRC) cells. Whsc1 loss promoted tumorigenesis via a noncell-autonomous mechanism in an [Apc.sup.min/+] mouse model, CRC organoids, and xenografts. Mechanistically, we found that the IFN-[gamma]/STAT1 signaling axis stimulated WHSC1 expression and, in turn, that WHSC1 directly interacted with NLRC5 to promote MHC-I gene expression, but not that of PD-L1. Concordantly, silencing Whsc1 diminished MHC-I levels, impaired antitumor immunity, and blunted the effect of immune checkpoint blockade. Patient cohort analysis revealed that WHSC1 expression positively correlated with enhanced MHC-I expression, tumor-infiltrating T cells, and favorable disease outcomes. Together, our findings establish a tumor-suppressive function of WHSC1 that relays IFN-[gamma] signaling to promote antigen presentation on CRC cells and provide a rationale for boosting WHSC1 activity in immunotherapy., Introduction MHC class I (MHC-I) molecules, in complex with [beta]-2-microglobulin (B2M), are loaded with endogenous peptides generated by the proteasome and imported into the ER by the heterodimeric TAP1/TAP2 transporter [...]

The gut microbiome shapes local and systemic immunity. The liver is presumed to be a protected sterile site. As such, a hepatic microbiome has not been examined. Here, we showed a liver microbiome in mice and humans that is distinct from that of the gut and is enriched in Proteobacteria. It undergoes dynamic alterations with age and is influenced by the environment and host physiology. Fecal microbial transfer experiments revealed that the liver microbiome is populated from the gut in a highly selective manner. Hepatic immunity is dependent on the microbiome, specifically the bacteroidetes species. Targeting bacteroidetes with oral antibiotics reduced hepatic immune cells by approximately 90%, prevented antigen-presenting cell (APC) maturation, and mitigated adaptive immunity. Mechanistically, our findings are consistent with presentation of bacteroidetes-derived glycosphingolipids to NKT cells promoting CCL5 signaling, which drives hepatic leukocyte expansion and activation, among other possible host-microbe interactions. Collectively, we reveal a microbial/glycosphingolipid/NKT/CCL5 axis that underlies hepatic immunity., Introduction Gut microbiota represent the most abundant and diverse collection of commensal organisms in the body (1). The intestinal microbiome plays a fundamental role in shaping the host immune system [...]