Biology subjects

Zhu, W.

Publications and source records attributed to Zhu, W..

At least 109 records · Page 6Linked to original sources

bioRxiv2023

Sterile Soil as Prebiotics Mitigate Intergenerational Loss of Gut Microbial Diversity and Anxiety-Like Behavior Induced by Antibiotics in mice

The decline in gut microbial diversity of modern human is closely associated with the rising prevalence of various diseases. It is imperative to investigate the underlying causes of gut microbial loss and the rescue measures. Although the impact of non-perinatal antibiotic use on gut microbiota has been recognized, its intergenerational effects remain unexplored. Our previous research has highlighted soil in the farm environment as a key prebiotic for gut microbiome health by restoring gut microbial diversity and balance. In this study, we investigated the intergenerational consequences of antibiotic exposure and the therapeutic potential of soil prebiotics. We treated mice with vancomycin and streptomycin for 2 weeks continuously, followed by 4-8 weeks of withdrawal period before breeding. The process was repeated across 3 generations. Half of the mice in each generation received an oral soil prebiotic intervention. We assessed gut microbial diversity, anxiety behavior, microglia reactivity, and gut barrier integrity across generations. The antibiotics exposure led to a decrease in gut microbial diversity over generations, along with aggravated anxiety behavior, microglia abnormalityies, and altered intestinal tight junction protein expression. Notably, the third generation of male mice exhibited impaired reproductive capacity. Oral sterile soil intervention restored gut microbial diversity in adult mice across generations, concomitantly rescuing abnormalities in behavior, microglia activity, and intestinal barrier integrity. In conclusion, this study simulated an important process of the progressive loss gut microbiota diversity in modern human and demonstrated the potential of sterile soil as a prebiotic to reverse this process. The study provides a theoretical and experimental basis for the research and therapeutic interventions targeting multiple modern chronic diseases related to intestinal microorganisms.

microbiology↗

bioRxiv2023

FGF-21 Conducts a Liver-Brain-Kidney Axis to Promote Renal Cell Carcinoma

Metabolic homeostasis is one of the most exquisitely tuned systems in mammalian physiology. Metabolic homeostasis requires multiple redundant systems to cooperate to maintain blood glucose concentrations in a narrow range, despite a multitude of physiological and pathophysiological pressures. Cancer is one of the canonical pathophysiological settings in which metabolism plays a key role. In this study, we utilized REnal Gluconeogenesis Analytical Leads (REGAL), a liquid chromatography-mass spectrometry/mass spectrometry-based stable isotope tracer method that we developed to show that in conditions of metabolic stress, the fasting hepatokine fibroblast growth factor-21 (FGF-21)1, 2 coordinates a liver-brain-kidney axis to promote renal gluconeogenesis. FGF-21 promotes renal gluconeogenesis by enhancing {beta}2 adrenergic receptor (Adrb2)-driven, adipose triglyceride lipase (ATGL)-mediated intrarenal lipolysis. Further, we show that this liver-brain-kidney axis promotes gluconeogenesis in the renal parenchyma in mice and humans with renal cell carcinoma (RCC). This increased gluconeogenesis is, in turn, associated with accelerated RCC progression. We identify Adrb2 blockade as a new class of therapy for RCC in mice, with confirmatory data in human patients. In summary, these data reveal a new metabolic function of FGF-21 in driving renal gluconeogenesis, and demonstrate that inhibition of renal gluconeogenesis by FGF-21 antagonism deserves attention as a new therapeutic approach to RCC.

physiology↗

bioRxiv2023

In vitro screening of non-antibiotic alternative growth promoter combinations in broilers

Available research on non-antibiotic alternative growth promoter (NAGPs) mainly focuses on the effect of a single preparation on the substitution effect of antibiotics. However, different NAGP might work together in harmony. Studies related to NAGP combinations are lacking. This study aimed to screen six non-antibiotic alternative growth promoter combinations (NAGPCs) in vitro so as to find a better alternative method to ensure feed efficiency and the broiler health. Pepsin and 42-d broiler ileal fluid were used for the in vitro digestion test, and the optimal addition levels of NAGPs and NAGPCs were selected based on dry matter (DM) and organic matter (OM) digestibility, microbiota of digestive fluid, and antioxidant capacity of digestive fluid. Results showed the optimum addition amount of Mannose oligosaccharide (MOS), fruit oligosaccharide (FOS), mannanase (MAN), Bacillus subtilis (BS), sodium butyrate (SB), guanidinoacetic acid (CA), xylanase (XYL), glucose oxidase (GO), and phytase (PT) were 0.2%, 0.9%, 0.03%, 0.05%, 0.08%, 0.002%, 0.008%, and 0.004%. The six best combinations were 0.2%MOS + 0.03%MAN + 0.15%SB, 0.2%MOS + 0.03%MAN + 0.05%BS, 0.2%MOS + 0.9%FOS + 0.15%SB, 0.2%MOS + 0.9%FOS + 0.05%BS, 0.2%MOS + 0.9%FOS + 0.03%MAN, and 0.2%MOS + 0.05%BS + 0.004%PT. In conclusion, NAGPCs improved the apparent digestibility of ileal DM and OM, intestinal flora and antioxidant capacity. Comparatively, under this condition, using NAGPC has more beneficial effects than using non-antibiotic alternative growth promoter.

zoology↗

bioRxiv2023

MPL36, a major plasminogen (PLG) receptor in pathogenic Leptospira, has an essential role during infection

Leptospirosis, a zoonosis with worldwide distribution, is caused by pathogenic spirochetes belonging to the genus Leptospira. Bacterial outer membrane proteins (OMPs), particularly those with surface-exposed regions, play crucial roles in pathogen dissemination and virulence mechanisms. Here we characterized the leptospiral Membrane Protein L36 (MPL36), a rare lipoprotein A (RlpA) homolog with a C-terminal Sporulation related (SPOR) domain, as an important virulence factor in pathogenic Leptospira. Our results showed that MPL36 is surface exposed and expressed during infection. Recombinant MPL36 (rMPL36) showed high plasminogen (PLG)-binding ability determined by lysine residues of the C-terminal region of the protein, with ability to convert bound-PLG to active plasmin. Using Kochs molecular postulates, we determined that a mutant of mpl36 has a reduced PLG-binding ability, leading to a decreased capacity to adhere and translocate MDCK cell monolayers. Using recombinant protein and mutant strains, we determined that the MPL36-bound plasmin (PLA) can degrade fibrinogen. Finally, our mpl36 mutant had a significant attenuated phenotype in the hamster model for acute leptospirosis. Our data indicates that MPL36 is the major PLG binding protein in pathogenic Leptospira, and crucial to the pathogens ability to attach and interact with host tissues during infection. The MPL36 characterization contributes to the expanding field of bacterial pathogens that explore PLG for their virulence, advancing the goal to close the knowledge gap regarding leptospiral pathogenesis while offering a novel potential candidate to improve diagnostic and prevention of this important zoonotic neglected disease. Author SummaryAs part of their diverse virulence machinery, bacterial pathogens bind to human plasminogen (PLG) providing them with a proteolytic platform that promotes invasiveness, dissemination, and virulence. Leptospirosis is the leading zoonotic disease in morbidity and mortality worldwide. The burden of this neglected disease will continue to raise given the effects of climate change and social inequality, important drivers of disease. Furthermore, the gap of knowledge regarding leptospiral pathogenesis has negatively impacted the development of sensitive diagnostic tools and effective prevention methods. Previous studies have shown that pathogenic Leptospira, the causative agent of leptospirosis, can interact with PLG through different protein candidates. In this work, we characterized one of those candidates, Membrane Protein L36 (MPL36), as the main leptospiral plasminogen binding protein. Using genetically modified mutants, in vivo, and in vitro assays we provided evidence that MPL36 can bound PLG, promotes adherence to host cells and subsequent translocation, and degrades fibrinogen by converting bound-PLG to PLA, thus essential to leptospiral virulence. This work contributes to the growing field of bacterial pathogens exploring PLG to increase their virulence, while highlighting important new knowledge on leptospiral pathogenesis. MPL36 is an important candidate to be explored on the continued effort to improve diagnostic and prevention of this important zoonotic disease.

microbiology↗

bioRxiv2023

The immune receptor SNC1 monitors helper NLRs targeted by a bacterial effector

Plants deploy intracellular receptors to counteract pathogen effectors that suppress cell-surface receptor-mediated immunity. To what extent pathogens manipulate also immunity mediated by intracellular receptors, and how plants tackle such manipulation, remains unknown. Arabidopsis thaliana encodes three very similar ADR1 class helper NLRs (ADR1, ADR1-L1 and ADR1-L2), which play key roles in plant immunity initiated by intracellular receptors. Here, we report that Pseudomonas syringae AvrPtoB, an effector with E3 ligase activity, can suppress ADR1-L1- and ADR1-L2-mediated cell death. ADR1, however, evades such suppression by diversification of two ubiquitination sites targeted by AvrPtoB. The intracellular sensor NLR SNC1 interacts with and guards the CCR domains of ADR1-L1 and ADR-L2. Removal of ADR1-L1 and ADR1-L2 or delivery of AvrPtoB activates SNC1, which then signals through ADR1 to trigger immunity. Our work not only uncovers the long sought-after physiological function of SNC1 in pathogen defense, but also that reveals how plants can use dual strategies, sequence diversification and a multiple layered guard-guardee system, to counteract pathogen attack on core immunity functions.

plant biology↗

bioRxiv2023

Human CCR6+ Th cells show both an extended stable gradient of Th17 activity and imprinted plasticity

Th17 cells have been investigated in mice primarily for their contributions to autoimmune diseases. However, the pathways of differentiation of Th17 and related (type 17) cells and the structure of the type 17 memory population in humans are not well understood; such understanding is critical for manipulating these cells in vivo. By exploiting differences in levels of surface CCR6, we found that human type 17 memory cells, including individual T cell clonotypes, form an elongated continuum of type 17 character along which cells can be driven by increasing ROR{gamma}t. This continuum includes cells preserved within the memory pool with potentials that reflect the early preferential activation of multiple over single lineages. The CCR6+ cells phenotypes and epigenomes are stable across cell divisions under homeostatic conditions. Nonetheless, activation in polarizing and non-polarizing conditions can yield additional functionalities, revealing, respectively, both environmentally induced and imprinted mechanisms that contribute differentially across the continuum to yield the unusual plasticity ascribed to type 17 cells.

immunology↗

bioRxiv2022

Effects of nonantibiotic alternative growth promoter combinations on nutrient utilization, digestive enzyme activity, intestinal morphology, and cecal microflora of broilers

Given the ban on antibiotic growth promoters, six nonantibiotic alternative growth promoter combinations (NAGPCs) for broilers were evaluated. All birds were fed pellets of two basal diets--starter (0-21 d) and grower (22-42 d)--with either enramycin (ENR) or NAGPC supplemented. 1) control + 100 mg/kg ENR; 2) control diet (CON, basal diet); 3) control + 2,000 mg/kg mannose oligosaccharide (MOS) + 300 mg/kg mannanase (MAN) + 1,500 mg/kg sodium butyrate (SB) (MMS); 4) control + 2,000 mg/kg MOS + 300 mg/kg MAN + 500 mg/kg Bacillus subtilis (BS) (MMB); 5) control + 2,000 mg/kg MOS + 9,000 mg/kg fruit oligosaccharide (FOS) + 1,500 mg/kg SB (MFS); 6) control + 9,000 mg/kg FOS + 500 mg/kg BS (MFS) (MBP). The experiment used a completely random block design with six replicates per group: 50 Ross 308 broilers in the starter phase and 16 in the grower phase. All the NAGPCs significantly improved (P < 0.01) utilization of dry matter (DM), organic matter (OM), crude protein (CP), and crude fat (CF) on d 21, significantly increased DM, OM (P < 0.01), and CP (P < 0.05) on d 42, and significantly increased (P < 0.01) villus height, crypt depth, and the villus height to crypt depth ratio in the jejunum and ileum compared with CON and ENR. On d 21 and 42, trypsin, lipase, and amylase activity of the duodenum significantly increased in the MMS, MMB, MFB, and MFM groups. Compared with ENR and CON, MMS, MMB, and MBP increased the abundance of Firmicutes at d 21 and of Bacteroides at d 42 whereas MMB, MFB, and MBP decreased the abundance of Proteobacteria at d 21 and 42. Overall, the NAGPCs were found to have some beneficial effects and may be used as effective antibiotic replacements in broilers.

biophysics↗

bioRxiv2022

Prenatal maternal stress promotes neural stem cell proliferation in the ependymal-subventricular zone of adult male offspring

Perturbations during critical time windows during embryonic development can lead to adverse functional consequences that manifest later in life. Here, we report that prenatal maternal stress (PNS) during the peak of embryonic neurogenesis (E14-delivery) dramatically increased numbers of proliferating neural stem/progenitor cells (NSC/NPCs) in the ependymal-subventricular zone (E-SVZ) and neuroblasts (NBs) in the rostral migratory stream and newborn neurons in the olfactory bulb (OB) of male mouse offspring without causing significant cell death or a deficit in cell migration to the OB. Mechanistically, bulk and single-nucleus transcriptomic analyses showed that PNS affected gene regulatory networks controlling cell cycle progression and stem cell maintenance, maturation of neural circuits, and gliogenesis in prenatally stressed (STR) offspring. More specifically, we found that prenatal exposure to mild maternal restraint-stress sustained MAPK (ERK) activity in the E-SVZ and thus prolonged NSC/NPC/NB proliferation in stressed brains. Moreover, we found PNS disorganized the cytoarchitecture of the glomerular layer of the OB, which may directly relate to the deficit in discriminating different social orders in stressed offspring. Compared to STR males, their female littermates showed less change in the number of proliferating cells in the E-SVZ.

neuroscience↗

bioRxiv2022

Evaluation of AlphaFold-Multimer prediction on multi-chain protein complexes

MotivationDespite near-experimental accuracy on single-chain predictions, there is still scope for improvement among multimeric predictions. Methods like AlphaFold-Multimer and FoldDock can accurately model dimers. However, how well these methods fare on larger complexes is still unclear. Further, evaluation methods of the quality of multimeric complexes are not well established. ResultsWe analysed the performance of AlphaFold-Multimer on a homology-reduced dataset of homo- and heteromeric protein complexes. We highlight the differences between the pairwise and multi-interface evaluation of chains within a multimer. We describe why certain complexes perform well on one metric (e.g., TM-score) but poorly on another (e.g., DockQ). We propose a new score, Predicted DockQ version 2 (pDockQ2), to estimate the quality of each interface in a multimer. Finally, we modelled protein complexes (from CORUM) and identified two highly confident structures that do not have sequence homology to any existing structures. AvailabilityAll scripts, models, and data used to perform the analysis in this study are freely available at https://gitlab.com/ElofssonLab/afm-benchmark. Contactarne@bioinfo.se Supplementary informationSupplementary data are available at Bioinformatics online.

bioinformatics↗

bioRxiv2022

Genome-wide identification and analysis of analysis of BURP genes in Triticum aestivum

Plant-specific BURP genes are involved in most aspects of plant development and in diverse stress responses. However, there has been no comprehensive and systematic research on the wheat (Triticum aestivum L.) BURP gene family. We comprehensively identified 54 BURP genes in wheat and 12, 23, and 32 BURP genes, respectively, in its three progenitor species, Triticum urartu, Aegilops tauschii, and Triticum dicoccoides. By phylogenetic analysis, we classified the wheat BURP genes into five subfamilies: BURP VI, BURP VII, RD22-like, PG1{beta}-like, and the newly defined BURP VIII. BURP genes were distributed unevenly on 20 chromosomes, and 33 (61%) were anchored in the distal chromosome segments. Analysis of gene duplication events showed that segmental duplication was the main contributor to the expansion of this gene family in wheat. Assessment of tissue-specific and stress-induced expression indicated that most BURP members are heavily involved in plant development and responses to various stress conditions. RNA-seq data revealed ten TaBURP genes expressed specifically in spikes.

bioinformatics↗

bioRxiv2022

Universal chimeric Fcγ receptor T cells with appropriate affinity for IgG1 antibody exhibit optimal antitumor efficacy

Developing universal CARs with improved flexible targeting and controllable activities is urgently needed. While several studies have suggested the potential of CD16a in tandem with monoclonal antibodies to construct universal CAR T cells, the weak affinity between them is one of the limiting factors for efficacy. Herein, we systematically investigated the impact of Fc{gamma} receptor (Fc{gamma}R) affinity on CAR T cells properties by constructing universal CARs using Fc{gamma} receptors with different affinities for IgG1 antibodies, namely CD16a, CD32a, and CD64. We demonstrated that the activities of these universal CAR T cells on tumor cells could be redirected and regulated by IgG1 antibodies. In xenografted mice, 64CAR chimeric Jurkat cells with the highest affinity showed significant antitumor effects in combination with herceptin in the Her2 low expression U251 MG model. However, in the CD20 high expression Raji model, 64CAR caused excessive activation of CAR-T cells, which resulted in cytokine release syndrome (CRS) and the decline of antitumor activity, and 32CAR with a moderate affinity brought the best efficacy. Our work extended the knowledge about Fc{gamma}R-based universal CAR T cells and suggested that only the Fc{gamma}RCAR with an appropriate affinity can offer the optimal antitumor advantages of CAR T cells. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=82 SRC="FIGDIR/small/513394v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1348ceorg.highwire.dtl.DTLVardef@10eb32org.highwire.dtl.DTLVardef@c12aeforg.highwire.dtl.DTLVardef@1e9c9ea_HPS_FORMAT_FIGEXP M_FIG C_FIG Universal CAR T cells based on Fc{gamma} receptors exhibit a specific tumor-killing effect. However, the affinities of Fc{gamma} receptors greatly influence the efficacy and adverse effects in vivo.

immunology↗

bioRxiv2022

Resistance exercise protects mice from protein-induced metabolic dysfunction

Low protein (LP) diets extend the lifespan of diverse species, and are associated with improved metabolic health in both rodents and humans. Paradoxically, many athletes and bodybuilders consume high protein (HP) diets and protein supplements, yet are both fit and metabolically healthy. Here, we examine this paradox using weight pulling, a validated progressive resistance exercise training regimen, in mice fed either an LP diet or an isocaloric HP diet. We find that despite having lower food consumption than the LP group, HP-fed mice gain significantly more fat mass than LP-fed mice when not exercising, while weight pulling protected HP-fed mice from this excess fat accretion. The HP diet augmented exercise-induced hypertrophy of the forearm flexor complex, and weight pulling ability increased more rapidly in the exercised HP-fed mice. Surprisingly, exercise did not protect from HP-induced changes in glycemic control. Our results confirm that HP diets can augment muscle hypertrophy and accelerate strength gain induced by resistance exercise without negative effects on fat mass, and also demonstrate that LP diets may be advantageous in the sedentary. Our results highlight the need to consider both dietary composition and activity, not simply calories, when taking a precision nutrition approach to health.

physiology↗

bioRxiv2022

Tissue-Specific and Interorgan Metabolic Reprogramming Maintains Tolerance to Sepsis

Reprogramming metabolism is of great therapeutic interest for reducing morbidity and mortality during sepsis-induced critical illness1. Disappointing results from randomized controlled trials targeting glutamine and antioxidant metabolism in patients with sepsis have begged for both identification of new metabolic targets, and a deeper understanding of the metabolic fate of glutamine at the systemic and tissue-specific manner2-4. In critically ill patients versus elective surgical controls, skeletal muscle transcriptional metabolic reprogramming is comprised of reduced expression of genes involved in mitochondrial metabolism, electron transport, and glutamate transport, with concomitant increases in glutathione cycling, glutamine, branched chain, and aromatic amino acid transport. To analyze putative interorgan communications during sepsis, we performed systemic and tissue specific metabolic phenotyping in a murine polymicrobial sepsis model, cecal ligation and puncture. In the setting of drastically elevated inflammatory cytokines, we observed >10% body weight loss, >50% reductions in oxygen consumption and carbon dioxide production, and near full suppression of voluntary activity for the 48 hours following sepsis as compared to sham-operated controls. We found increased correlations in the metabolome between liver, kidney, and spleen, with drastic loss of correlations between the heart and quadriceps metabolome and all other organs, pointing to a shared metabolic signature within vital abdominal organs, and unique metabolic signatures for skeletal and cardiac muscle during sepsis. A lowered GSH:GSSG and elevated AMP:ATP ratio in the liver underlie the significant upregulation of isotopically labeled glutamines contribution to TCA anaplerosis and glutamine-derived glutathione biosynthesis; meanwhile, the skeletal muscle and spleen were the only organs where glutamines contribution to the TCA cycle was significantly suppressed. These results highlight tissue-specific mitochondrial reprogramming, rather than global mitochondrial dysfunction, as a mechanistic consequence of sepsis. Using a multi-omic approach, we demonstrate a model by which sepsis-induced proteolysis fuels the livers production of anaplerotic substrates and the antioxidant glutathione to sustain tolerance to sepsis.

physiology↗

bioRxiv2022

Stromal STAT5-mediated trophic activity regulates hematopoietic multipotent progenitor niche factors

Signal transducer and activator of transcription 5 (STAT5a and STAT5b) are intrinsically critical for normal hematopoiesis but are also expressed in stromal cells. Here, STAT5ab knockout (KO) was generated with a variety of bone marrow hematopoietic and stromal Cre transgenic mouse strains. Vav1-Cre, the positive control for loss of multipotent hematopoietic function, surprisingly dysregulated niche factor mRNA expression and deleted STAT5ab in CD45neg cells. Single cell transcriptome analysis of bone marrow from wild-type or Vav1-Cre KO mice showed hematopoietic stem cell myeloid commitment priming and upregulated protein translation genes. Nes+ cells were detected in both CD45neg and CD45+ clusters and deletion of STAT5ab with Nes-Cre caused hematopoietic repopulating defects. To follow up on these promiscuous Cre promoter deletions in CD45neg and CD45+ bone marrow cell populations, more stroma-specific Cre strains were generated and demonstrated reduction in multipotent hematopoietic progenitors. Functional support for niche-supporting activity was assessed using STAT5-deficient MSCs. With Lepr-Cre, niche factor mRNAs were downregulated by STAT5ab deletion with validation of reduced IGF-1 and CXCL12 proteins. Furthermore, computational analyses (differential expression/co-expression) revealed a key role for STAT5ab/Cish balance with Cish strongly co-expressed in MSCs and HSCs primed for differentiation. Therefore STAT5ab-associated gene regulation supports the bone marrow microenvironment.

cell biology↗

bioRxiv2022

Taxonomic and metagenomic analyses define the development of the microbiota in the chick

Chicks are ideal to follow the development of the intestinal microbiota and to understand how a pathogen perturbs this developing population. Taxonomic/metagenomic analyses captured the development of the chick microbiota in unperturbed chicks and in chicks infected with Salmonella enterica serotype Typhimurium (STm) during development. Taxonomic analysis suggests that colonization by the chicken microbiota takes place in several waves. The cecal microbiota stabilizes at day 12 post-hatch with prominent Gammaproteobacteria and Clostridiales. Introduction of S. Typhimurium at day 4 post-hatch disrupted the expected waves of intestinal colonization. Taxonomic and metagenomic shotgun sequencing analyses allowed us to identify species present in uninfected chicks. Untargeted metabolomics suggested different metabolic activities in infected chick microbiota. This analysis, and GS-MS on ingesta confirmed that lactic acid in cecal content coincides with the stable presence of Enterococci in STm infected chicks. Unique metabolites including 2-isopropylmalic acid, an intermediate in the biosynthesis of leucine, was present only in the cecal content of STm infected chicks. Metagenomic data suggested that the microbiota in STm infected chicks contained a higher abundance of genes, from STm itself, involved in branched chain amino acid synthesis. We generated a deletion mutant in ilvC (STM3909) encoding ketol-acid-reductoisomerase, a gene required for the production of L-isoleucine and L-valine. {Delta}ilvC mutants are disadvantaged for growth during competitive infection with the wild type. Providing the ilvC gene in trans restored growth of the {Delta}ilvC mutant. Our integrative approach identified biochemical pathways used by STm to establish a colonization niche in the chick intestine during development. IMPORTANCEChicks are an ideal model to follow the development of the intestinal microbiota and to understand how a pathogen perturbs this developing population. Using taxonomic and metagenomic analyses we captured the development of the chick microbiota to 19 days post-hatch in unperturbed chicks and in chicks infected with Salmonella enterica serotype Typhimurium (STm). We show that normal development of the microbiota takes place in waves, and is altered in the presence of a pathogen. Metagenomics and metabolomics suggested that branched chain amino acid biosynthesis is especially important for Salmonella growth in the infected chick intestine. Salmonella mutants unable to make L-isoleucine and L-valine colonize the chick intestine poorly. Restoration of the pathway for biosynthesis of these amino acids restored the colonizing ability of Salmonella. Integration of multiple analyses allowed us to correctly identify biochemical pathways used by Salmonella to establish a niche for colonization in the chick intestine during development.

microbiology↗

bioRxiv2022

Commensal Neisseria species share immune suppressive mechanisms with Neisseria gonorrhoeae

Neisseria gonorrhoeae is a highly adapted human sexually transmitted pathogen that can cause symptomatic infections associated with localized inflammation as well as asymptomatic and subclinical infections, particularly in females. Gonococcal infection in humans does not generate an effective immune response in most cases, which contributes to both transmission of the pathogen and reinfection after treatment. Neisseria gonorrhoeae is known to evade and suppress human immune responses through a variety of mechanisms. Commensal Neisseria species that are closely related to N. gonorrhoeae, such as N. cinerea, N. lactamica, N. elongata, and N. mucosa, rarely cause disease and instead asymptomatically colonize mucosal sites for prolonged periods of time without evoking clearing immunologic responses. We have shown previously that N. gonorrhoeae inhibits the capacity of antigen-pulsed dendritic cells to induce CD4+ T cell proliferation in vitro. Much of the suppressive effects of N. gonorrhoeae on dendritic cells can be recapitulated either by outer-membrane vesicles released from the bacteria or by purified PorB, the most abundant outer-membrane protein in Neisseria gonorrhoeae. We show here that three commensal Neisseria species, N. cinerea, N. lactamica and N. mucosa, show a comparable capacity to suppress dendritic cell-induced T cell proliferation through mechanisms similar to those demonstrated previously for N. gonorrhoeae, including inhibition by purified PorB. Our findings suggest that some immune-evasive properties of pathogenic N. gonorrhoeae are shared with commensal Neisseria species and may contribute to the ability of both pathogens and commensals to cause prolonged mucosal colonization in humans.

microbiology↗

bioRxiv2022

Mechanistic basis for targeting homologous recombination defective liver cancer via synthetic lethality

Many cancers harbour homologous recombination defects (HRD). The identification of PARP inhibitors as synthetic lethal with HRD has led to new therapeutic strategies for HRD cancers. Here we report a subtype of HRD that is caused by the perturbation of a previously uncharacterised proteasome variant, CDW19S, in hepatitis virus B (HBV) positive hepatocellular carcinoma (HBVHCC). CDW19S contains the 19S complex decorated with a Cullin 4 ubiquitin ligase (CRL4WDR70) that is assembled at broken chromatin and regulates end processing nucleases. The HBV oncoprotein, HBx, prevents integration of the CRL4 backbone into CDW19S. We show that CDW19S directly ubiquitinates ADRM1Rpn13, targeting it for degradation, and that HBx interferes with this, leading to the imposition of a novel ADRM1Rpn13-dependent resection barrier that results in HRD and promotes carcinogenesis with concurrent TP53 loss. Using cellular and patient-derived xenograft models we demonstrate that HRD in HBVHCC can be exploited to restrict tumour progression. Our work clarifies the mechanism of a virally-induced HRD and suggests a new route for targeted HBVHCC therapy.

cancer biology↗

bioRxiv2022

A novel anti-PD-L1/IL-15 immunocytokine overcomes resistance to PD-L1 blockade and elicits potent antitumor immunity

Despite the demonstrated immense potential of immune checkpoint inhibitors in various types of cancers, only a minority of patients respond to these therapies. Immunocytokines designed to deliver an immune-activating cytokine directly to the immunosuppressive tumor microenvironment (TME) and block the immune checkpoint simultaneously may provide a strategic advantage over the combination of two single agents. To increase response rate to checkpoint blockade, in this study we developed a novel immunocytokine (LH01) composed of the antibody against programmed death-ligand 1 (PD-L1) fused to IL-15 receptor alpha-sushi domain/IL-15 complex. We demonstrate that LH01 efficiently binds mouse or human PD-L1 and maintains IL-15 stimulatory activity. In syngeneic mouse models, LH01 showed improved antitumor efficacy and safety versus anti-PD-L1 plus LH02 (Fc-Sushi-IL15) combination and overcame resistance to anti-PD-L1 treatment. Mechanistically, the dual anti-immunosuppressive function of LH01 led to activation of both the innate and adaptive immune response and decreased levels of transforming growth factor-{beta}1 (TGF-{beta}1) within the TME. Furthermore, combination therapy with LH01 and bevacizumab exerts synergistic antitumor effects in HT29 colorectal xenograft model. Collectively, our results provide supporting evidence that fusion of anti-PD-L1 and IL-15 might be a potent strategy to treat patients with cold tumors or resistance to checkpoint blockade.

immunology↗