Biology subjects

Tang, P.

Publications and source records attributed to Tang, P..

At least 19 recordsLinked to original sources

bioRxiv2026

Pulmonary colonization of Candida albicans drives breast cancer lung metastasis via candidalysin

The intratumoral mycobiome is emerging as a key modulator of cancer progression, with specific fungal taxa as potential biomarkers. However, whether and how mycobiomes colonizing distant organs contribute to tumor evolution remains largely unexplored. Here, we identify selective enrichment of Candida albicans in breast cancer lung metastases. Mechanistically, the fungal virulence factor candidalysin activates pulmonary mast cells, which release chemotactic mediators that expand immunosuppressive populations and suppress cytotoxic lymphocyte activity, remodeling the lung into a metastasis-permissive microenvironment. Analysis of clinical isolates and isogenic mutants further demonstrates that candidalysin secretion levels dictate metastasis-promoting potential. Informed by these findings, we developed a combination regimen that concurrently eliminates fungal colonization, stabilizes mast cells, and reverses the immunosuppressive microenvironment, thereby significantly curtailing metastatic progression. Collectively, our study establishes pulmonary C. albicans colonization as a driver of breast cancer lung metastasis and provides a mechanistic framework for targeting mycobiome-host interactions in metastatic disease.

cancer biology↗

bioRxiv2026

IL-36γ Drives Th9 cell Differentiation via IκBζ to Sustain Antitumor Immunity

Th9/Tc9 cells polarized with TGF-{beta} and IL-4 exhibit superior antitumor efficacy, prompting extensive efforts to optimize their differentiation protocols and augment therapeutic potency. In the current study, we identified IL-36{gamma} as a potent cytokine that synergizes with TGF-{beta} to robustly drive Th9 differentiation both in the presence and absence of IL-4. IL-36{gamma}-programmed Th9 cell subsets exhibited phenotypic and transcriptional profiles identical to classic Th9 cells. Mechanistically, IL-36{gamma} drove Th9 cell differentiation through amplifying key signaling pathways such as STAT6, STAT5, and NF-{kappa}B that are essential for classic Th9 programming. Notably, we uncovered a novel regulatory axis wherein IL-36{gamma} upregulates the transactivation factor I{kappa}B{zeta}, which directly governs Th9 lineage specification. In in adoptive cell therapy (ACT) models, IL-36{gamma}-polarized Th9 cell subsets demonstrated enhanced antitumor efficacy, attributable to their sustained persistence, reduced exhaustion markers and stem-like/memory properties. Collectively, this study elucidates a previously unrecognized I{kappa}B{zeta}-dependent mechanism underpinning Th9 differentiation and highlights the translational potential of IL-36{gamma}-engineered Th9 cells as a valuable ACT strategy for refractory tumors.

immunology↗

bioRxiv2026

Loss of Propionyl-CoA Carboxylase Reprograms Hepatic Metabolism by Suppressing Mitochondrial Pyruvate Carboxylation and Fatty Acid Oxidation

Propionic acidemia (PA) is an inborn error of metabolism caused by propionyl-CoA carboxylase (PCC) deficiency due to mutations in either PCCA or PCCB. Without proper management, the disease is associated with high mortality. Even with dietary restriction, patients often develop complications later in life, and the underlying pathological mechanisms remain poorly understood. The liver is the primary organ responsible for propionyl-CoA metabolism, yet the metabolic alterations induced by PCC deficiency in the liver have not been systematically investigated. In this study, we used a hepatocyte model of PA-- PCCAnull-HepG2 cells--to comprehensively examine metabolic alterations using stable isotope-based metabolic flux analysis. The PCCA knockout recapitulated key metabolic features of PA in HepG2 cells. Furthermore, PCCA deficiency reduced mitochondrial fatty acid oxidation while increasing glucose oxidation through pyruvate dehydrogenase. In contrast, pyruvate anaplerosis via pyruvate carboxylase was markedly reduced in PCCA knockout cells. This reduction in anaplerotic flux impaired the capacity for gluconeogenesis and lipid synthesis, consistent with observations from in vivo studies in Pcca-/- (A138T) mice. Additionally, branched-chain keto acid catabolism was reduced in PCCA knockout HepG2 cells. Threonine showed minimal metabolic contribution in this model, further supporting the role of propionate as a major source of propionyl-CoA production. Collectively, these findings highlight the metabolic vulnerabilities associated with PCC deficiency and underscore the increased risk of prolonged fasting in patients with PA, particularly those with severe disease.

genetics↗

bioRxiv2025

Dynamic and Heterogeneous Distribution of Trichomonasvirus Species in Trichomonas vaginalis

Trichomonasvirus (TVV) is a double-stranded RNA virus from the Pseudototiviridae family that exclusively infects Trichomonas vaginalis, the protozoan responsible for the most common non-viral sexually transmitted infection. Within the Trichomonasvirus genus, five distinct viral species have been identified, and intriguingly, a single T. vaginalis isolate can simultaneously harbor multiple TVV species. Previous studies have explored the impact of TVV infection on the physiology and virulence of T. vaginalis, yet findings remain inconsistent and often contradictory. We propose that these discrepancies stem from the heterogeneous intracellular distribution of TVV within individual cells of the same T. vaginalis isolate. To investigate this, we employed ultra-deep single-cell RNA sequencing and immunofluorescence assays to examine multiple T. vaginalis isolates. Our results revealed striking variability in the proportion of infected cells carrying the same viral species, even within a single isolate. The present study is the first to demonstrate the dynamic and non-uniform intracellular distribution of TVV at the single-cell level. These findings challenge previous assumptions and provide a new perspective on the intricate virus-host interactions between TVV and T. vaginalis, offering new avenues for further research into their complex relationship. Author SummaryTrichomonas vaginalis is a parasitic protozoan responsible for the most prevalent non-viral sexually transmitted infection worldwide. In 1985, researchers discovered a double-stranded RNA (dsRNA) virus within T. vaginalis, which was later named Trichomonasvirus (TVV). This virus is believed to influence the hosts gene expression, impacting cytoadherence, drug susceptibility, and virulence proteins. However, studies on TVV-host interaction have produced conflicting results, with some genes appearing upregulated in one experiment but downregulated in another or vice versa. We hypothesize that these inconsistencies stem from the non-uniform distribution of TVV among individual cells within the same T. vaginalis isolate. Based on the experimental data from ultra-deep single-cell sequencing and immuno-localization, our study reveals that TVVs intracellular distribution is highly heterogeneous and dynamic. These findings challenge the prevailing assumption that TVV is uniformly and statically distributed. This heterogeneity underscores the need to reassess previous research on TVV-T. vaginalis interactions, as earlier studies may have overlooked this crucial factor.

microbiology↗

bioRxiv2025

Improved nucleoside (2'-deoxy)ribosyltransferases maximize enzyme promiscuity while maintaining catalytic efficiency

Nucleoside analogues have been extensively used to treat viral and bacterial infections and cancer for the past 60 years. However, their chemical synthesis is complex and often requires multiple steps and a dedicated synthetic route for every new nucleoside to be produced. Wild type nucleoside 2'-deoxyribosyltransferase enzymes are promising for biocatalysis. Guided by the structure of the enzyme from the thermophilic organism Chroococcidiopsis thermalis PCC 7203 (CtNDT) bound to the ribonucleoside analogue Immucillin-H, we designed mutants of CtNDT and the psychrotolerant Bacillus psychrosaccharolyticus (BpNDT) to improve catalytic efficiency with 3'-deoxynucleosides and ribonucleosides, while maintaining nucleobase promiscuity to generate over 100 distinct nucleoside products. Enhanced catalytic efficiency towards ribonucleosides and 3'-deoxyribonucleosides occurred via gains in turnover rate, rather than improved substrate binding. We determined crystal structures of two engineered variants as well as kinetic parameters with different substrates, unveiling molecular details underlying their expanded substrate scope. Our rational approach generated robust enzymes and a roadmap for reaction conditions applicable to a wide variety of substrates. Insert Table of Contents artwork here O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=98 SRC="FIGDIR/small/641663v2_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@3ef466org.highwire.dtl.DTLVardef@11f55b0org.highwire.dtl.DTLVardef@32d0dcorg.highwire.dtl.DTLVardef@2e22cc_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2024

Comparative genomics of the sexually transmitted parasite Trichomonas vaginalis reveals relaxed and convergent evolution and genes involved in spillover from birds to humans

Trichomonas vaginalis is the causative agent of the venereal disease trichomoniasis which infects men and women globally and is associated with serious outcomes during pregnancy and cancers of the human reproductive tract. Trichomonads parasitize a range of hosts in addition to humans including birds, livestock, and domesticated animals. Recent genetic analysis of trichomonads recovered from columbid birds has provided evidence that these parasite species undergo frequent host-switching, and that a current epoch spillover event from columbids likely gave rise to T. vaginalis in humans. We undertook a comparative evolutionary genomics study of seven trichomonad species, generating chromosome-scale reference genomes for T. vaginalis and its avian sister species Trichomonas stableri, and assemblies of five other species that infect birds and mammals. Human-infecting trichomonad lineages have undergone recent and convergent genome size expansions compared to their avian sister species, and the major contributor to their increased genome size is increased repeat expansions, especially multicopy gene families and transposable elements, with genetic drift likely a driver due to relaxed selection. Trichomonads have independently host-switched twice from birds to humans, and genes implicated in the transition to the human host include those associated with host tissue adherence and phagocytosis, extracellular vesicles, and CAZyme virulence factors.

microbiology↗

bioRxiv2024

Neutrophil Extracellular Trap gene expression signatures identify prognostic and targetable signaling axes for inhibiting metastasis of pancreatic tumours

Tumour associated neutrophils (TANs) can promote metastasis through the interaction of Neutrophil Extracellular Traps (NETs) with tumour cells. Here, we examined the contribution of NETs in the progression of Pancreatic Ductal Adenocarcinoma (PDAC), which is characterized by high metastatic propensity. We carried out consensus clustering and pathway enrichment analysis of NET-related genes in an integrated cohort of 369 resectable and metastatic PDAC patient tumour samples, and compiled two gene expression signatures comprising of either, integrin-actin cytoskeleton, and Epithelial to Mesenchymal Transition (EMT) signaling, or cell death signaling, which identified patients with very poor to better overall survival, respectively. Tumour Infiltrating neutrophils and NETs associate with ITGB1, CCDC25 and ILK, within clinical and experimental PDAC tumours. Functionally, exposure of PDAC cells to NETs identified a cytoskeletal dynamic-associated CCDC25/ITGB1/ILK signaling complex which stimulates EMT and migration/ invasion. Furthermore, NETosis-driven experimental metastasis of PDAC cells is significantly inhibited by ILK knock down. Our data identify novel NET-related gene expression signatures for PDAC patient stratification, and reveal targetable signaling axes to prevent and treat disease progression and metastasis.

cancer biology↗

bioRxiv2024

Dissecting compounded hepatocyte injury in a model of MASLD progression from human induced pluripotent stem cells

Drug discovery for multifactorial diseases like metabolic dysfunction-associated steatotic liver disease (MASLD) remains challenging due to inadequate models and untargeted drug screenings. We combined stem-cell-based modeling with computational drug predictions identifying flavin pathways as therapeutic targets in MASLD. For disease stage-specific discovery, we established a MASLD testing model, compounding metabolic triggers to intensify mitochondrial crisis. In vitro injuries included adipo- and myokines, immune cell co-culture, and genomic risk factors. Benchmarking experiments revealed similarities with advanced human MASLD. To query therapeutic compounds, protein-protein-interaction networks, weighted gene co-expression, and knowledge graph-based analyses independently predicted flavin adenine dinucleotide (FAD) as an anti-MASLD factor. Dysregulated flavoproteomes in vitro and in vivo-in pediatric and adult MASLD patients- supported our flavin network-focused strategy. We established therapeutic FAD concentrations to mitigate metabolic injury and fibro-inflammation in human multicellular liver organoids and other assays. We enhanced therapeutic FAD effects through genetic mitochondrial biogenic augmentation and identified orally available flavo-active compounds--including Aspirin--restoring mitochondrial respiration. Our study demonstrates how integrating stem cell-derived disease modeling with computed drug predictions can expedite therapeutic discovery.

cell biology↗

bioRxiv2024

Immobilized Nucleoside 2'-Deoxyribosyltransferases from Extremophiles for Nucleoside Biocatalysis

The synthesis of nucleosides is crucial for pharmaceutical and biotechnological applications, acting as drugs and as essential building blocks for numerous therapeutic agents. However, most enzymes employed in nucleoside biocatalysis are not recycled, possess limit stability and strict substrate selection for ribonucleosides or 2'deoxyribonucleosides. We employed 2'deoxyribonucleoside transferase (NDT) enzymes from thermophilic and psychrophilic bacteria to demonstrate they can be immobilized to en-hance specific activity, stability, and recyclability. NDT enzymes from Chroococcidiopsis thermalis (CtNDT), and Bacillus psychrosaccharolyticus (BpNDT) were immobilized by covalent attachment to chitosan beads. A double mutant of CtNDT, capable of generating 3'deoxyribonucleosides, showed remarkable and increased stability after immobilization when compared to the same enzyme in solution. Furthermore, we demonstrated the recyclability of immobilized biocatalysts, with a tenfold improvement in reaction yield over 20 consecutive cycles, highlighting the practicality and sustainability of the developed immobilization method. We used our strategy to produce a pharmaceutically relevant 3'deoxyribonucleoside (2-fluoro-3'-deoxyadenosine). This highlights the importance of efficient immobilization techniques to enhance catalytic properties of NDT enzymes, expanding their utility in biocatalysis.

biochemistry↗

bioRxiv2024

Paraptosome: A Novel Pathological Feature in Paraptotic Cell Death

Paraptosis is a novel form of programmed cell death characterized by distinct morphological features such as swelling of the endoplasmic reticulum and mitochondria, and cytoplasmic vacuolation. Unlike apoptosis, paraptosis does not involve the activation of caspases or DNA fragmentation. These unique features make paraptosis an intriguing target for cancer therapy, particularly against apoptosis-resistant cells. Here, we report a novel morphological feature of paraptosis: the formation of high-density spherical structure, which we tentatively term "paraptosome." We found that these putative paraptosomes originate from the Golgi apparatus, appearing as high-density formations under light microscopy and colocalizing with the trans-Golgi marker {beta}4GALT1-RFP. Time-lapse confocal microscopy and immunostaining demonstrated that putative paraptosomes form due to Golgi stress or disintegration, leading to severe disruption of Golgi function. Furthermore, we show that paraptosis inducers such as glabridin, morusin, and honokiol can cause significant alterations in the endoplasmic reticulum, mitochondria, autophagosomes, and lysosomes in U251MG glioblastoma cells; however, the formation of putative paraptosomes is not induced by isolated stress inducers. Collectively, these findings suggest that the putative paraptosome may be a novel characteristic structure of paraptosis. The discovery of paraptosomes provides a unique marker for defining paraptotic cell death and offers new insights into the characteristic pathological phenomena associated with multiple organelle dysfunction. This finding broadens the scope of cell biology research by introducing a new structural paradigm linked to paraptosis and may have implications for developing targeted therapies against apoptosis-resistant cancers.

cell biology↗

bioRxiv2024

Linalool's Multifaceted Antimicrobial Potential: Unveiling its Antimicrobial Efficacy and Immunomodulatory Role Against Saprolegnia parasitica

Saprolegnia parasitica (S. parasitica) is one of the most virulent oomycete species in freshwater aquatic environments, causing severe saprolegniasis and leading to significant economic losses in the aquaculture industry. Thus far, the prevention and control of saprolegniasis face a shortage of medications. Linalool, a natural antibiotic alternative found in various essential oils, exhibits promising antimicrobial activity against a wide range of pathogens. In this study, the specific role of linalool in protecting S. parasitica infection at both in vitro and in vivo levels was investigated. Linalool showed multifaceted anti-oomycetes potential by both of antimicrobial efficacy and immunomodulatory efficacy. For in vitro test, linalool exhibited strong anti-oomycetes activity and mode of action included: (1) Linalool disrupted the cell membrane of the mycelium, causing the intracellular components leak out; (2) Linalool prohibited ribosome function, thereby inhibiting protein synthesis and ultimately affecting mycelium growth. Surprisingly, meanwhile we found the potential immune protective mechanism of linalool in the in vivo test: (1) Linalool enhanced the complement and coagulation system which in turn activated host immune defense and lysate S. parasitica cells; (2) Linalool promoted wound healing, tissue repair, and phagocytosis to cope with S. parasitica infection; (3) Linalool positively modulated the immune response by increasing the abundance of beneficial Actinobacteriota; (4) Linalool stimulated the production of inflammatory cytokines and chemokines to lyse S. parasitica cells. In all, our findings showed that linalool possessed multifaceted anti-oomycetes potential which would be a promising natural antibiotic alternative to cope with S. parasitica infection in the aquaculture industry.

microbiology↗

bioRxiv2023

14-3-3 binding motif phosphorylation disrupts Hdac4 organized condensates to stimulate cardiacreprogramming

Cell fate conversion is associated with extensive epigenetic and post translational modifications (PTMs) and architectural changes of sub-organelles and organelles, yet how these events are interconnected remains unknown. We report here the identification of a phosphorylation code in 14-3-3 binding motifs (PC14-3-3) that greatly stimulates induced cardiomyocyte (iCM) formation from fibroblasts. PC14-3-3 was identified in pivotal functional proteins for iCM reprogramming, including transcription factors and epigenetic factors. Akt1 kinase and PP2A phosphatase were a key writer and eraser of the PC14-3-3 code, respectively. PC14-3-3 activation induces iCM formation with the presence of only Tbx5. In contrast, PC14-3-3 inhibition by mutagenesis or inhibitor-mediated code removal abolished reprogramming. We discovered that key PC14-3-3 embedded factors, such as Hdac4, Mef2c, Nrip1, and Foxo1, formed Hdac4 organized inhibitory nuclear condensates. Notably, PC14-3-3 activation disrupted Hdac4 condensates to promote cardiac gene expression. Our study suggests that sub-organelle dynamics regulated by a post-translational modification code could be a general mechanism for stimulating cell reprogramming and organ regeneration. HighlightsO_LIA PC14-3-3 (phosphorylation code in 14-3-3 binding motifs) is identified in pivotal functional proteins, such as HDAC4 and Mef2c, that stimulates iCM formation. C_LIO_LIAkt1 kinase and PP2A phosphatase are a key writer and a key eraser of the PC14-3-3 code, respectively, and PC14-3-3 code activation can replace Mef2c and Gata4 in cardiac reprogramming. C_LIO_LIPC14-3-3 activation disrupts Hdac4 organized condensates which results in releasing multiple 14-3-3 motif embedded proteins from the condensates to stimulate cardiac reprogramming. C_LIO_LISub-organelle dynamics and function regulated by a post-translational modification code could be a general mechanism in stimulating cell reprogramming and organ regeneration. C_LI Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=150 SRC="FIGDIR/small/567913v1_ufig1.gif" ALT="Figure 1"> View larger version (52K): org.highwire.dtl.DTLVardef@1fec3aforg.highwire.dtl.DTLVardef@e13b16org.highwire.dtl.DTLVardef@ee354borg.highwire.dtl.DTLVardef@ecd58e_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2023

Mechanosensory and command contributions to the Drosophila grooming sequence

Flies groom in response to competing mechanosensory cues in an anterior to posterior order using specific legs. From behavior screens, we identified a pair of cholinergic command-like neurons, Mago-no-Te (MGT), whose optogenetic activation elicits thoracic grooming by hind legs. Thoracic grooming is typically composed of body sweeps and leg rubs in alternation, but clonal analysis coupled with amputation experiments revealed that MGT activation only commands the body sweeps: initiation of leg rubbing requires contact between leg and thorax. With new electron microscopy (EM) connectome data for the ventral nerve cord (VNC), we uncovered a circuit-based explanation for why stimulation of posterior thoracic mechanosensory bristles initiates cleaning by the hind legs. Our previous work showed that flies weigh mechanosensory inputs across the body to select which part to groom, but we did not know why the thorax was always cleaned last. Here, the connectome for the VNC enabled us to identify a pair of GABAergic inhibitory neurons, UMGT1, that receive diverse sensory inputs and synapse onto both MGT and components of its downstream pre-motor circuits. Optogenetic activation of UMGT1 suppresses thoracic cleaning, representing a mechanism by which mechanosensory stimuli on other body parts could take precedence in the grooming hierarchy. We also mapped the pre-motor circuit downstream of MGT, including inhibitory feedback connections that may enable rhythmicity and coordination of limb movement during thoracic grooming.

neuroscience↗

bioRxiv2023

Cardiomyocyte-specific deletion of PTP1B protects against HFD-induced cardiomyopathy through direct regulation of cardiac metabolic signaling

BackgroundHeart failure is the number one cause of death worldwide and mortality is directly correlated with the high incidence of obesity and diabetes. Indeed, the epidemic phenomenon of obesity was projected to reach 50% in the US by the year 2030. However, the mechanisms linking metabolic dysfunction with heart disease are not clear. Protein Tyrosine Phosphatase 1B (PTP1B), a negative regulator of insulin signaling, is considered to be an emerging therapeutic target against the development of obesity, insulin resistance, and diabetes. Increased PTP1B levels and activity have been observed in brain, muscle and adipose tissues isolated from obese and/or diabetic animals, as well as in human obese human patients. Its role, however, and the mechanisms by which it modulates metabolic processes in the heart remain unknown. Method and ResultsWe generated cardiomyocyte (CM)-specific PTP1B knock-out (PTP1Bfl/fl::MHCCre/+) mice to investigate the cardiomyocyte-specific role of PTP1B in response to high fat diet (HFD)-induced cardiac dysfunction. While we did not observe any physiological or functional cardiac differences at baseline, in response to HFD, we found that PTP1Bfl/fl::MHCCre/+ mice were protected against development of cardiac hypertrophy, mitochondrial dysfunction, and diminished cardiac steatosis. Metabolomics data revealed that hearts with CM-specific deletion of PTP1B had increased fatty acid oxidation and NAD+ metabolism, but reduced glucose metabolism; we further validated these findings by real-time qPCR analysis. Mechanistically, we identified a novel PTP1B PKM2-AMPK axis in the heart, which acts as a molecular switch to promote fatty acid oxidation. In this regard, we identified that hearts from PTP1Bfl/fl::MHCCre/+ mice had upregulated levels of nicotinamide adenine dinucleotide (NAD+) and NAD phosphate (NADPH), leading to higher levels of nicotinamide phosphoribosyl transferase (NAMPT), the rate-limiting step of the NAD+ salvage pathway and an enzyme associated with obesity and diabetes. ConclusionsTogether, these results suggest that CM-specific deletion of PTP1B mediates a substrate switch from glucose to fatty acid metabolism, protecting hearts against development of HFD-induced cardiac hypertrophy and dysfunction through mechanisms involving a novel PTP1B/PKM2/AMPK axis that is critical for the regulation of NAMPT and NAD+ biosynthesis.

molecular biology↗

bioRxiv2022

Heterosynaptic Plasticity of the Visuo-auditory Projection Requires Cholecystokinin released from Entorhinal Cortex Afferents

The entorhinal cortex is involved in establishing enduring visuo-auditory associative memory in the neocortex. Here we explored the mechanisms underlying this synaptic plasticity related to projections from the visual and entorhinal cortices to the auditory cortex, using optogenetics of dual pathways. High-frequency laser stimulation (HFLS) of the visuo-auditory projection did not induce long-term potentiation (LTP). However, after pairing with sound stimulus, the visuo-auditory inputs were potentiated following either infusion of cholecystokinin (CCK) or HFLS of the entorhino-auditory CCK-expressing projection. Combining retrograde tracing and RNAscope in situ hybridization, we show that CCK expression is higher in entorhinal cortex neurons projecting to the auditory cortex than in those originating from the visual cortex. In the presence of CCK, potentiation in the neocortex occurred when the pre-synaptic input arrived 200 ms before post-synaptic firing, even after just five trials of pairing. Behaviorally, inhibition of CCK signaling blocked the generation of associative memory. Our results indicate that neocortical visuo-auditory association is formed through heterosynaptic plasticity, which depends on release of CCK in the neocortex mostly from entorhinal afferents.

neuroscience↗

bioRxiv2021

Probiotic consortia improve anti-viral immunity to SARS-CoV-2 in ferrets

Probiotics have been suggested as one solution to counter detrimental health effects by SARS-CoV-2, however, data so far is scarce. We tested the effect of two probiotic consortia, OL-1 and OL-2, against SARS-CoV-2 in ferrets and assessed their effect on cytokine production and transcriptome in a human monocyte-derived macrophage (Mf) and dendritic cell (DC) model. The results showed that the consortia significantly reduced the viral load, modulated immune response, and regulated viral receptor expression in ferrets compared to placebo. In human Mf and DC model, OL-1 and OL-2 induced cytokine production and genes related to SARS-CoV-2 anti-viral immunity. The study results indicate that probiotic stimulation of the ferret immune system leads to improved anti-viral immunity against SARS-COV-2 and that critical genes and cytokines for anti-SARS-CoV-2 immunity are stimulated in human immune cells in vitro. The effect of the consortia against SARS-CoV-2 warrants further investigations in human clinical trials.

immunology↗

bioRxiv2021

Inositol lipid synthesis is widespread in host-associated Bacteroidetes

Ubiquitous in eukaryotes, inositol lipids have finely tuned roles in cellular signaling and membrane homeostasis. In Bacteria, however, inositol lipid production is rare. Recently, the prominent human gut bacterium Bacteroides thetaiotaomicron (BT) was reported to produce inositol lipids, including inositol sphingolipids, but the pathways remain ambiguous and their prevalence unclear. Here, we investigated the gene cluster responsible for inositol lipid synthesis in BT using a novel strain with inducible control of sphingolipid synthesis. We characterized the biosynthetic pathway from myo-inositol-phosphate (MIP) synthesis to phosphoinositol-dihydroceramide, including structural and kinetic studies of the enzyme MIP synthase (MIPS). We determined the crystal structure of recombinant BT MIPS with bound NAD cofactor at 2.0 [A] resolution, and identified the first reported phosphatase for the conversion of bacterially-derived phosphatidylinositol phosphate (PIP) to phosphatidylinositol (PI). Transcriptomic analysis indicated inositol production is nonessential but its loss alters BT capsule expression. Bioinformatic and lipidomic comparisons of Bacteroidetes species revealed a novel second putative pathway for bacterial PI synthesis without a PIP intermediate. Our results indicate that inositol sphingolipid production, via one of the two pathways, is widespread in host-associated Bacteroidetes, and may be implicated in host interactions both indirectly via the capsule and directly through inositol lipid provisioning.

microbiology↗

bioRxiv2020

CARD8 inflammasome mediates pyroptosis of HIV-1-infected cells by sensing viral protease activity

HIV-1 has high mutation rates and exists as mutant swarms in the host. Rapid evolution of HIV-1 allows the virus to outpace host immune system, leading to viral persistence. Novel approaches to target immutable components are needed to clear HIV-1 infection. Here we report a pattern-recognition receptor CARD8 that senses enzymatic activity of the HIV-1 protease, which is indispensable for the virus. All subtypes of HIV-1 can be sensed by CARD8 despite substantial viral diversity. HIV-1 evades CARD8 sensing because the viral protease remains inactive in infected cells prior to viral budding. Induction of premature intracellular activation of the viral protease triggers CARD8 inflammasome-mediated pyroptosis of HIV-1-infected cells. This strategy leads to clearance of latent HIV-1 in patient CD4+ T cells after virus reactivation. Taken together, our study identifies CARD8 as an inflammasome sensor of HIV-1 that holds promise as a strategy for clearance of persistent HIV-1 infection.

immunology↗