TMPRSS2 and TMPRSS4 promote SARS-CoV-2 infection of human small intestinal enterocytes

Gastrointestinal symptoms and fecal shedding of SARS-CoV-2 RNA are frequently observed in COVID-19 patients. However, it is unclear whether SARS-CoV-2 replicates in the human intestine and contributes to possible fecal-oral transmission. Here, we report productive infection of SARS-CoV-2 in ACE2⁺ mature enterocytes in human small intestinal enteroids. Expression of two mucosa-specific serine proteases, TMPRSS2 and TMPRSS4, facilitated SARS-CoV-2 spike fusogenic activity and promoted virus entry into host cells. We also demonstrate that viruses released into the intestinal lumen were inactivated by simulated human colonic fluid, and infectious virus was not recovered from the stool specimens of COVID-19 patients. Our results highlight the intestine as a potential site of SARS-CoV-2 replication, which may contribute to local and systemic illness and overall disease progression.

TMPRSS2 and TMPRSS4 promote SARS-CoV-2 infection of human small intestinal enterocytes

Gastrointestinal symptoms and fecal shedding of SARS-CoV-2 RNA are frequently observed in COVID-19 patients. However, it is unclear whether SARS-CoV-2 replicates in the human intestine and contributes to possible fecal-oral transmission. Here, we report productive infection of SARS-CoV-2 in ACE2+ mature enterocytes in human small intestinal enteroids. Expression of two mucosa-specific serine proteases, TMPRSS2 and TMPRSS4, facilitated SARS-CoV-2 spike fusogenic activity and promoted virus entry into host cells. We also demonstrate that viruses released into the intestinal lumen were inactivated by simulated human colonic fluid, and infectious virus was not recovered from the stool specimens of COVID-19 patients. Our results highlight the intestine as a potential site of SARS-CoV-2 replication, which may contribute to local and systemic illness and overall disease progression.

Reverse Genetics Reveals a Role of Rotavirus VP3 Phosphodiesterase Activity in Inhibiting RNase L Signaling and Contributing to Intestinal Viral Replication In Vivo

Our understanding of how rotavirus (RV) subverts host innate immune signaling has greatly increased over the past decade. However, the relative contribution of each virus-encoded innate immune antagonist has not been fully studied in the context of RV infection in vivo Here, we present both in vitro and in vivo evidence that the host interferon (IFN)-inducible 2'-5'-oligoadenylate synthetase (OAS) and RNase L pathway effectively suppresses the replication of heterologous RV strains. VP3 from homologous RVs relies on its 2'-5'-phosphodiesterase (PDE) domain to counteract RNase L-mediated antiviral signaling. Using an RV reverse-genetics system, we show that compared to the parental strain, VP3 PDE mutant RVs replicated at low levels in the small intestine and were shed less in the feces of wild-type mice, and such defects were rescued in Rnasel-/- suckling mice. Collectively, these findings highlight an important role of VP3 in promoting viral replication and pathogenesis in vivo in addition to its well-characterized function as the viral RNA-capping enzyme.IMPORTANCE Rotaviruses are significant human pathogens that result in diarrhea, dehydration, and deaths in many children around the world. Rotavirus vaccines have suboptimal efficacy in low- to middle-income countries, where the burden of the diseases is the most severe. With the ultimate goal of improving current vaccines, we aim to better understand how rotavirus interacts with the host innate immune system in the small intestine. Here, we demonstrate that interferon-activated RNase L signaling blocks rotavirus replication in a strain-specific manner. In addition, virus-encoded VP3 antagonizes RNase L activity both in vitro and in vivo These studies highlight an ever-evolving arms race between antiviral factors and viral pathogens and provide a new means of targeted attenuation for next-generation rotavirus vaccine design.

The Role of Innate Immunity in Regulating Rotavirus Replication, Pathogenesis, and Host Range Restriction and the Implications for Live Rotaviral Vaccine Development

Rotaviruses (RVs) are important causative agents of viral gastroenteritis in the young of most mammalian species studied, including humans, in which they are the most important cause of severe gastroenteritis worldwide despite the availability of several safe and effective vaccines. Replication of RVs is restricted in a host species-specific manner, and this barrier is determined predominantly by the host interferon (IFN) signaling and the ability of different RV strains to successfully negate IFN activation and amplification pathways. In addition, viral attachment to the target intestinal epithelial cells also regulates host range restriction. Several studies have focused on the role of the innate immune response in regulating RV replication and pathogenesis. The knowledge accrued from these efforts is likely to result in rational attenuation of RV vaccines to closely match circulating (and host species-matched) virus strains. In this chapter, we review prevalent models of RV interactions with innate immune factors, viral strategies employed to regulate their function, and the implications of these findings for improved RV vaccine development.

Recombinant HIV-1 vaccine candidates based on replication-defective flavivirus vector

Multiple approaches utilizing viral and DNA vectors have shown promise in the development of an effective vaccine against HIV. In this study, an alternative replication-defective flavivirus vector, RepliVax (RV), was evaluated for the delivery of HIV-1 immunogens. Recombinant RV-HIV viruses were engineered to stably express clade C virus Gag and Env (gp120TM) proteins and propagated in Vero helper cells. RV-based vectors enabled efficient expression and correct maturation of Gag and gp120TM proteins, were apathogenic in a sensitive suckling mouse neurovirulence test, and were similar in immunogenicity to recombinant poxvirus NYVAC-HIV vectors in homologous or heterologous prime-boost combinations in mice. In a pilot NHP study, immunogenicity of RV-HIV viruses used as a prime or boost for DNA or NYVAC candidates was compared to a DNA prime/NYVAC boost benchmark scheme when administered together with adjuvanted gp120 protein. Similar neutralizing antibody titers, binding IgG titers measured against a broad panel of Env and Gag antigens, and ADCC responses were observed in the groups throughout the course of the study, and T cell responses were elicited. The entire data demonstrate that RV vectors have the potential as novel HIV-1 vaccine components for use in combination with other promising candidates to develop new effective vaccination strategies.

Role of Microtearing Turbulence in DIII-D High Bootstrap Current Fraction Plasmas

We report on the first direct comparisons of microtearing turbulence simulations to experimental measurements in a representative high bootstrap current fraction (f_{BS}) plasma. Previous studies of high f_{BS} plasmas carried out in DIII-D with large radius internal transport barriers (ITBs) have found that, while the ion energy transport is accurately reproduced by neoclassical theory, the electron transport remains anomalous and not well described by existing quasilinear transport models. A key feature of these plasmas is the large value of the normalized pressure gradient, which is shown to completely stabilize conventional drift-wave and kinetic ballooning mode instabilities in the ITB, but destabilizes the microtearing mode. Nonlinear gyrokinetic simulations of the ITB region performed with the cgyro code demonstrate that the microtearing modes are robustly unstable and capable of driving electron energy transport levels comparable to experimental levels for input parameters consistent with the experimental measurements. These simulations uniformly predict that the microtearing mode fluctuation and flux spectra extend to significantly shorter wavelengths than the range of linear instability, representing significantly different nonlinear dynamics and saturation mechanisms than conventional drift-wave turbulence, which is also consistent with the fundamental tearing nature of the instability. The predicted transport levels are found to be most sensitive to the magnetic shear, rather than the temperature gradients more typically identified as driving turbulent plasma transport.

[Expression and mechanism of mast cell activating molecules and their antibodies in allergic rhinitis and nasal polyps]

Objective:To analyze the relationship and mechanism of mast cell with allergic rhinitis and nasal polyps. Method:From January 2018 to June 2018, all the inpatients in Otolaryngology Department were examined by nasal endoscopy and CT before operation. They were divided into three groups: 30 patients with allergic rhinitis（AR group） and 30 patients with nasal polyps（NP group） as the experimental group; 30 patients with nasal septum correction after partial inferior turbinectomy alone as the control group（N group）. Clinical data, peripheral blood and nasal mucosa were collected. The percentage of eosinophils in peripheral blood was detected by automatic hematology analyzer. The levels of anti-IgE antibody, FcεRIα and anti-FcεRIα antibody in serum were detected by ELISA. The levels of serum IgE were detected by velocity scattering turbidimetry. HE was used to observe the histopathological changes in the three groups. Immunohistochemical method was used to analyze the expression of tryptase and FcεRIα in the experimental group and the control group. Result:The percentage of eosinophils, IgE, anti-IgE antibody, FcεRIα and anti-FcεRIα antibodies in AR group were significantly higher than those in control group（P<0.05）; the percentage of eosinophils, FcεRIα and anti-FcεRIα antibodies in NP group were significantly higher than those in healthy control group（P<0.05）. There was no significant difference in IgE and anti-IgE antibodies among three groups（P>0.05）. The eosinophil percentage, IgE and anti-IgE antibody levels in AR group were significantly higher than that in NP group（P<0.05）; there were no differences in FcεRIα and anti-FcεRIα antibody levels between AR group and NP group（P>0.05）; There was no significant difference in eosinophil infiltration between the two groups; The brown tryptase-positive mast cells and FcεRIα-positive mast cells were found in the submucosa and interstitium of nasal mucosa. Conclusion:The high expression of FcεRIα and its antibody in the serum of patients with allergic rhinitis and nasal polyps indicated that this antibody system was involved in the occurrence and development of allergic rhinitis and nasal polyps. Local allergy with mast cells as the core might play an important role in the occurrence and development of nasal polyps. The possible role of mast cells in the formation of nasal polyps and the specific mechanism deserve further study.

P711Histamine promotes atherosclerotic plaque instability via STAT6-dependent macrophage pyroptosis

Background

Atherosclerotic plaque formation and rupture is the primary cause for cardiovascular diseases. It's known that cell death and inflammation are crucial processes leading to atherosclerosis, which involves an important role of histamine. The aim of the present study is to determine the function of signal transducer and activator of transcription 6 (STAT6) in histamine-induced macrophage pyroptosis and plaque instability.

Methods

We constructed APOE/STAT6 double knock out (DKO) mice via hybridization of ApoE−/− and STAT6−/− mice. 20 ApoE−/− mice (control) and 20 DKO mice were challenged with high-fat diet for 12 weeks while 10 in each group were intraperitoneally infused with histamine (400ug/kg) every other day. The extent and instability of atherosclerotic plaque were determined by oil-red staining, HE staining, immunofluorescence staining and electron microscopy. Changes in subsets of immune cells were evaluated by flow cytometry. Plasma cytokines were assessed by ELISA. Microarray analysis was applied to detect gene expressions while Western blot and real-time PCR was used to assess gene expression levels.

Results

Morphology studies revealed that histamine could promote plaque formation and vulnerability in ApoE−/− mice, whereas this effect was inhibited in DKO mice. FACS data showed that histamine injection could increase CD11b+Ly6Chigh M1 macrophages differentiation and pyroptosis and facilitate foam cells formation in ApoE−/− mice, which was also inhibited in DKO mice. Microarray analysis and in vitro studies exhibited that histamine could induce the up-regulation of pyrotosis-related proteins such as NLRP3, caspase-1 and MMPs via a STAT6-dependent pathway to promote macrophage pyroptosis and foam cell formation.

Conclusions

We have characterized a novel role for histamine in modulating atherosclerotic lesion development and progression. Moreover, our work have figured out the detailed mechanisms by which histamine modulates the pyroptosis of macrophages and the progress of unstable atherosclerotic plaques. We envision that this study may provide several potential therapeutic targets benefit for atherosclerosis treatment.

A new reliable test for crossmatching: microplate hydrogel immunoassay technology

OBJECTIVES

To provide a novel assay to detect incomplete antibodies in the crossmatching test.

BACKGROUND

There is a requirement in China that both major and minor crossmatch tests are required. Among all methods of crossmatching, the tube anti-human globulin test requires tedious washing steps and is time-consuming, whereas the microcolumn gel immunoassay anti-human globulin test is susceptible to sample quality.

METHODS

The process of the microplate hydrogel immunoassay anti-human globulin test involves the use of our patented hydrogel chromatography medium and U-bottom microplates pre-coated with goat anti-human globulin (AHG). A mixture of red blood cells (RBCs) and serum is centrifuged through the hydrogel under precise conditions. In incompatible reactions, the sensitised RBCs are captured by the pre-coated AHG and form a layer over the bottom of the well, whereas in compatible reactions, the unbound RBCs form a button at the bottom of the well. The sensitivity of this new approach and the performance when testing old specimens were evaluated.

RESULTS

This approach was more convenient and slightly more sensitive than the tube anti-human globulin test and was superior to the microcolumn gel immunoassay when testing old specimens.

CONCLUSION

In general, this assay is suitable for the routine clinical use of crossmatching to detect incomplete antibodies.

Investigation on the regulatory effect of PGE2 on ESCC cells through the trans-activation of EGFR by EP2 and the relevant mechanism

OBJECTIVE

To determine whether the combination of prostaglandin E2 (PGE2) and EP2, the subtype receptor of PGE2, could trans-activate the epidermal growth factor receptor (EGFR).

PATIENTS AND METHODS

In this experiment, we selected epithelial cells from normal esophageal mucosa as the negative control group, and the ESCC EC109 and TE-1 cell strain as the observation group. Real-time PCR and Western-blotting were used to detect the expression of EP2, EGFR and phosphorylated EGFR (p-EGFR). The pre-treatment of ESCC cell strains was carried out using Butaprost (special agonist of PGE2 and EP2) and RNAi of EP2, and we observed the expression of EP2, EGFR, and p-EGFR. WST-8 (CCK-8) was applied for the detection of the cell proliferation rate. The transwell invasion experiment was conducted for the detection of the invasion capability of cells. The expression of MMP-9 (matrix metalloproteinase-9), VEGF (vascular endothelial growth factor), pro-inflammatory factors (IL-6 and TNF-α) in the cell supernatant were detected using ELISA.

RESULTS

The high mRNA and protein expression of EP2, EGFR, and p-EGFR were found in the EC109 and TE-1 cell strains in the observation group, which were higher than those in the control group (p < 0.05). After the intervention of PGE2, EP2 expression was decreased and the p-EGFR expression was increased (p < 0.05). There was no variation found in the expression of EGFR (p > 0.05). After cells were intervened using Butaprost, the expressions of EP2 and p-EGFR were increased (p < 0.05), and there were no changes identified in the expression of EGFR (p > 0.05). After the intervention of RNAi, the expression of EP2 and p-EGFR was decreased (p < .05), and no changes were identified in the expression of EGFR (p > 0.05). After the intervention of PGE2 and Butaprost, great increases were seen in the cell proliferation rate, invasion capability, and the expression of MMP-9, VEGF, IL-6, and TNF-α in EC109 and TE-1 cell strains (p < 0.05), however, the intervention of RNAi could reduce above indexes (p < 0.05).

CONCLUSIONS

Through cell experiments, we verified that the combination of prostaglandin E2 (PGE2) and EP2, the subtype receptor of PGE2, could trans-activate the epidermal growth factor receptor (EGFR) to regulate the proliferation and invasion capability of esophageal squamous cell carcinoma (ESCC) cells, and secrete and express multiple cytokines, thus discovering the pathological mechanism of inflammation to carcinoma transition in the occurrence of ESCC, and providing the experimental evidence for the search of new target in the treatment of ESCC. ESCC cells can highly express the receptor subtype EP2 of PGE2 that can transactivate the EGFR, through which PGE2 is involved in the transition mechanism from inflammation to cancer.

Human VP8* mAbs neutralize rotavirus selectively in human intestinal epithelial cells

We previously generated 32 rotavirus-specific (RV-specific) recombinant monoclonal antibodies (mAbs) derived from B cells isolated from human intestinal resections. Twenty-four of these mAbs were specific for the VP8* fragment of RV VP4, and most (20 of 24) were non-neutralizing when tested in the conventional MA104 cell-based assay. We reexamined the ability of these mAbs to neutralize RVs in human intestinal epithelial cells including ileal enteroids and HT-29 cells. Most (18 of 20) of the "non-neutralizing" VP8* mAbs efficiently neutralized human RV in HT-29 cells or enteroids. Serum RV neutralization titers in adults and infants were significantly higher in HT-29 than MA104 cells and adsorption of these sera with recombinant VP8* lowered the neutralization titers in HT-29 but not MA104 cells. VP8* mAbs also protected suckling mice from diarrhea in an in vivo challenge model. X-ray crystallographic analysis of one VP8* mAb (mAb9) in complex with human RV VP8* revealed that the mAb interaction site was distinct from the human histo-blood group antigen binding site. Since MA104 cells are the most commonly used cell line to detect anti-RV neutralization activity, these findings suggest that prior vaccine and other studies of human RV neutralization responses may have underestimated the contribution of VP8* antibodies to the overall neutralization titer.

Self-management and Related Psychosocial Variables Among Renal Transplant Patients

OBJECTIVE

To explore the influential factors of kidney transplant patients' self-management, especially psychosocial variables.

STUDY DESIGN

This was a cross-sectional study.

METHODS

Questionnaires were administered to patients with the assistance of our team members to gather sociodemographic information, medical characteristics, self-management, social support, depression, and flourishing.

RESULTS

The study included 483 patients, 64.4% of whom were male. The score index of the total self-management scale was 81.95% and the "social psychology" dimension had the lowest index, at 75.63%. Higher scores for flourishing, shorter length of post-renal transplantation, more social support, lower body mass index, being female, and being employed were proved to be determinants of better self-management, and flourishing was identified as having the greatest influence. Some other indicators were also related to patients' self-management, particularly age, residence, income, hypertension, renal function, and depression.

CONCLUSION

The overall self-management of KT patients was middling, and the status of psychology management was not optimistic. This emphasized the importance of psychological intervention. For further exploration, flourishing was identified as contributing to better self-management, which implied that strengthening this factor could be another method of improving self-management, except that involves enhancing of social support and reducing depression. Age was also found to have differing degrees of influence on KT patients' self-management, which implies that younger patients should receive more support in self-management.

Clinical, neuroimaging and prognostic study of 127 cases with infarction of the corpus callosum

Background and purpose

The aim of this study was to retrospectively investigate clinical and neuroimaging characteristics in the largest sample size of patients with corpus callosum infarction to date and then to follow up these patients for 1 year to clarify the prognosis of this rare stroke entity.

Methods

A total of 127 patients with acute callosal infarction out of 5584 acute ischaemic stroke patients were included in this study. The recruited patients were divided into a pure callosal infarction group and a complex callosal infarction group (coupled with other infarct locations simultaneously), and clinical and neuroimaging features were analyzed. Some of the patients were followed up for 1 year to evaluate recurrence rate and mortality.

Results

The incidence of acute callosal infarction was 2.3%. Most patients presented with advanced neurological dysfunction with or without mild to moderate motor or sensory disorders on admission. The negative rate of computed tomography scan was still 76.4% even at >24 h after onset. Large‐artery atherosclerosis was the most common etiological type. Compared with complex callosal infarction, the pure callosal infarction group had more mental disorders (P = 0.030). Compared with common basal ganglia infarction, the pure callosal infarction group had better short‐term recovery (P = 0.016) but higher 1‐year mortality (P = 0.037). Age and mental disorders were independent risk factors for death in callosal infarction.

Conclusions

Callosal infarction is a white matter stroke that occurs with low incidence. Elderly patients with vascular risk factors showed sudden mental or cognitive disorders and callosal infarction could not be excluded. More attention should be paid to the early diagnosis and secondary prevention of callosal infarction because of its poor long‐term outcome.

Profiling of rotavirus 3'UTR-binding proteins reveals the ATP synthase subunit ATP5B as a host factor that supports late-stage virus replication

Genome replication and virion assembly of segmented RNA viruses are highly coordinated events, tightly regulated by sequence and structural elements in the UTRs of viral RNA. This process is poorly defined and likely requires the participation of host proteins in concert with viral proteins. In this study, we employed a proteomics-based approach, named RNA-protein interaction detection (RaPID), to comprehensively screen for host proteins that bind to a conserved motif within the rotavirus (RV) 3' terminus. Using this assay, we identified ATP5B, a core subunit of the mitochondrial ATP synthase, as having high affinity to the RV 3'UTR consensus sequences. During RV infection, ATP5B bound to the RV 3'UTR and co-localized with viral RNA and viroplasm. Functionally, siRNA-mediated genetic depletion of ATP5B or other ATP synthase subunits such as ATP5A1 and ATP5O reduced the production of infectious viral progeny without significant alteration of intracellular viral RNA levels or RNA translation. Chemical inhibition of ATP synthase diminished RV yield in both conventional cell culture and in human intestinal enteroids, indicating that ATP5B positively regulates late-stage RV maturation in primary intestinal epithelial cells. Collectively, our results shed light on the role of host proteins in RV genome assembly and particle formation and identify ATP5B as a novel pro-RV RNA-binding protein, contributing to our understanding of how host ATP synthases may galvanize virus growth and pathogenesis.

Fabrication and application of nanoporous polymer ion-track membranes

With the development of the nano-fabrication and nanofluidics, nanoporous membranes have shown great potential in applications such as molecular separation, energy conversion, and molecular sensing. However, their performance has often been limited by the trade-off between selectivity and permeability and the lack of scalability. The prospect of overcoming these problems with nanoporous polymer ion-track membranes is promising. Focusing on these membranes, this review provides a comprehensive overview of fabrication methods, including the traditional track-etching technique and the recently developed track-UV technique; characterization methods; transport mechanisms; and major properties and applications.

Introducing hydrophilic ultra-thin ZIF-L into mixed matrix membranes for CO2/CH4 separation

Mixed matrix membranes (MMMs) were developed by mixing hydrophilically modified two-dimensional (2D) imidazole framework (named as hZIF-L) flakes into a Pebax MH 1657 (Pebax) matrix, and designed to separate carbon dioxide/methane (CO₂/CH₄) mixtures. The hZIF-L flakes were important for increasing the effectiveness of the MMMs. First, the tannic acid (TA) etched hZIF-L flakes have a large number of microporous (1.8 nm) and two-dimensional anisotropic transport channels, which offered convenient gas transport channels and improved the permeability of CO₂. Second, the TA molecules provide the surface of the ZIF-L flakes with more hydrophilic functional groups such as carbonyl groups (C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O) and hydroxyl groups (–OH), which could effectively prevent non-selective interfacial voids and filler agglomeration in the Pebax matrix, and also presented strong binding ability to water and CO₂ molecules. The satisfactory interface compatibility and affinity with the CO₂ molecule promoted its permeability, solubility, and selectivity. As a result, the MMMs exhibited the highest performance of gas separation with the hZIF-L flake weight content of 5%, at which the CO₂ permeability and CO₂/CH₄ selectivity were 502.44 barrer and 33.82 at 0.2 MPa and 25 °C, respectively.

Schematic diagram of CO₂ transfer in Pebax/hZIF-L mixed matrix membranes.

Rotavirus VP3 targets MAVS for degradation to inhibit type III interferon expression in intestinal epithelial cells

Rotaviruses (RVs), a leading cause of severe diarrhea in young children and many mammalian species, have evolved multiple strategies to counteract the host innate immunity, specifically interferon (IFN) signaling through RV non-structural protein 1 (NSP1). However, whether RV structural components also subvert antiviral response remains under-studied. Here, we found that MAVS, critical for the host RNA sensing pathway upstream of IFN induction, is degraded by the RV RNA methyl- and guanylyl-transferase (VP3) in a host-range-restricted manner. Mechanistically, VP3 localizes to the mitochondria and mediates the phosphorylation of a previously unidentified SPLTSS motif within the MAVS proline-rich region, leading to its proteasomal degradation and blockade of IFN-λ production in RV-infected intestinal epithelial cells. Importantly, VP3 inhibition of MAVS activity contributes to enhanced RV replication and to viral pathogenesis in vivo. Collectively, our findings establish RV VP3 as a viral antagonist of MAVS function in mammals and uncover a novel pathogen-mediated inhibitory mechanism of MAVS signaling.

A coupled effect of dehydration and electrostatic interactions on selective ion transport through charged nanochannels

Selective ion transport is an essential feature of biological ion channels. Due to the subnanometer size and negatively charged surface of ion channels, the ion selectivity is affected by both dehydration effects and electrostatic interactions. Their coupled effect on selective ion transport, however, has been elusive. Here, using molecular dynamics simulations, we study ion (Li⁺ and Mg²⁺) transport through subnanometer carbon nanotubes (CNTs) with varying charge densities. Our results indicate that the dehydration effect governs the ionic transport at low surface charge densities, hence the nanochannel shows a selectivity for Li⁺ ions. In contrast, the nanochannel switches to a selectivity for Mg²⁺ ions as the electrostatic interaction between the cations and the negatively charged wall dominates the transport at high surface charge densities.

Impact of strain and dose of live yeast and yeast derivatives on in vitro ruminal fermentation of a high-grain diet at two pH levels

The objective of this study was to determine the effects of live yeast (LY) or yeast derivatives (YD) on gas production (GP), dry matter (DM) disappearance (DMD), fermentation characteristics, and microbial profiles in batch culture. The study was a completely randomized design with a factorial arrangement: 2 media pH × 5 yeasts × 4 dosages. An additional treatment of monensin (Mon) was added as a positive control for each pH level. Media pH was low (5.8) and high (6.5); the yeasts were three LY (LY1-3) and two YD (YD4-5); and doses were 0, 4 × 106, 8 × 106, and 1.6 × 107 cfu mL−1 for LY and 0, 15, 30, and 60 mg bottle−1 for YD. Substrate consisted of 10% silage and 90% concentrate (DM basis) and samples were incubated for 24 h. Media pH of 6.5 vs. 5.8, increased (P < 0.01) GP, DMD, and volatile fatty acid (VFA) concentrations but decreased (P < 0.01) NH3-N concentration and copy numbers of Ruminococcus albus, Ruminococcus flavefaciens, and Selenomonas ruminantium. Increasing dose of LY2 linearly (P < 0.05) increased DMD. Total VFA concentration was greater with LY2 (P < 0.01) than LY3 and YD5 at pH 6.5. Overall, adding yeast products improved (P < 0.05) DMD at pH 5.8, and increased VFA concentration compared with Mon. These results indicate that in vitro GP and DMD of a high-grain diet varied with source and dose of yeast supplementation. Some yeast products have the potential to improve fermentation of feedlot diets when supplemented at appropriate doses.

New mitochondrial DNA synthesis enables NLRP3 inflammasome activation

Dysregulated NLRP3 inflammasome activity results in uncontrolled inflammation, which underlies many chronic diseases. Although mitochondrial damage is needed for the assembly and activation of the NLRP3 inflammasome, it is unclear how macrophages are able to respond to structurally diverse inflammasome-activating stimuli. Here we show that the synthesis of mitochondrial DNA (mtDNA), induced after the engagement of Toll-like receptors, is crucial for NLRP3 signalling. Toll-like receptors signal via the MyD88 and TRIF adaptors to trigger IRF1-dependent transcription of CMPK2, a rate-limiting enzyme that supplies deoxyribonucleotides for mtDNA synthesis. CMPK2-dependent mtDNA synthesis is necessary for the production of oxidized mtDNA fragments after exposure to NLRP3 activators. Cytosolic oxidized mtDNA associates with the NLRP3 inflammasome complex and is required for its activation. The dependence on CMPK2 catalytic activity provides opportunities for more effective control of NLRP3 inflammasome-associated diseases.