Deep sequencing of the gut microbiomes of 1135 participants from a Dutch population-based cohort shows relations between the microbiome and 126 exogenous and intrinsic host factors, including 31 ...intrinsic factors, 12 diseases, 19 drug groups, 4 smoking categories, and 60 dietary factors. These factors collectively explain 18.7% of the variation seen in the interindividual distance of microbial composition. We could associate 110 factors to 125 species and observed that fecal chromogranin A (CgA), a protein secreted by enteroendocrine cells, was exclusively associated with 61 microbial species whose abundance collectively accounted for 53% of microbial composition. Low CgA concentrations were seen in individuals with a more diverse microbiome. These results are an important step toward a better understanding of environment-diet-microbe-host interactions.
RATIONALE:Evidence suggests that the gut microbiome is involved in the development of cardiovascular disease, with the host–microbe interaction regulating immune and metabolic pathways. However, ...there was no firm evidence for associations between microbiota and metabolic risk factors for cardiovascular disease from large-scale studies in humans. In particular, there was no strong evidence for association between cardiovascular disease and aberrant blood lipid levels.
OBJECTIVES:To identify intestinal bacteria taxa, whose proportions correlate with body mass index and lipid levels, and to determine whether lipid variance can be explained by microbiota relative to age, sex, and host genetics.
METHODS AND RESULTS:We studied 893 subjects from the LifeLines-DEEP population cohort. After correcting for age and sex, we identified 34 bacterial taxa associated with body mass index and blood lipids; most are novel associations. Cross-validation analysis revealed that microbiota explain 4.5% of the variance in body mass index, 6% in triglycerides, and 4% in high-density lipoproteins, independent of age, sex, and genetic risk factors. A novel risk model, including the gut microbiome explained ≤25.9% of high-density lipoprotein variance, significantly outperforming the risk model without microbiome. Strikingly, the microbiome had little effect on low-density lipoproteins or total cholesterol.
CONCLUSIONS:Our studies suggest that the gut microbiome may play an important role in the variation in body mass index and blood lipid levels, independent of age, sex, and host genetics. Our findings support the potential of therapies altering the gut microbiome to control body mass, triglycerides, and high-density lipoproteins.
The glycosphingolipid GM1 binds cholera toxin (CT) on host cells and carries it retrograde from the plasma membrane (PM) through endosomes, the trans-Golgi (TGN), and the endoplasmic reticulum (ER) ...to induce toxicity. To elucidate how a membrane lipid can specify trafficking in these pathways, we synthesized GM1 isoforms with alternate ceramide domains and imaged their trafficking in live cells. Only GM1 with unsaturated acyl chains sorted efficiently from PM to TGN and ER. Toxin binding, which effectively crosslinks GM1 lipids, was dispensable, but membrane cholesterol and the lipid raft-associated proteins actin and flotillin were required. The results implicate a protein-dependent mechanism of lipid sorting by ceramide structure and provide a molecular explanation for the diversity and specificity of retrograde trafficking by CT in host cells.
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► Cells sort the glycosphingolipid GM1 by the structure of its ceramide domain (76/89) ► Only unsaturated GM1 ceramides sort retrograde all the way to the ER (64/78) ► GM1 is the vehicle that carries cholera toxin from plasma membrane to ER (61/74) ► Flotillin, cholesterol, and actin are required for GM1 sorting (55/64)
Chinnapen et al. examine how membrane lipids are sorted in mammalian cells and how the membrane glycosphingolipid GM1 can direct cholera toxin trafficking from cell surface into the ER of host cells to cause disease. Their results implicate a protein-dependent mechanism of sorting GM1, determined by its unsaturated ceramide domain.
For many bacterial respiratory infections, development of (severe) disease is preceded by asymptomatic colonization of the upper airways. For Streptococcus pneumoniae, the transition to severe lower ...respiratory tract infection is associated with an increase in nasopharyngeal colonization density. Insight into how the mucosal immune system restricts colonization may provide new strategies to prevent clinical symptoms. Several studies have provided indirect evidence that the mucosal adjuvant cholera toxin subunit B (CTB) may confer nonspecific protection against respiratory infections. Here, we show that CTB reduces the pneumococcal load in the nasopharynx, which required activation of the caspase-1/11 inflammasome, mucosal T cells, and macrophages. Our findings suggest that CTB-dependent activation of the local innate response synergizes with noncognate T cells to restrict bacterial load. Our study not only provides insight into the immunological components required for containment and clearance of pneumococcal carriage, but also highlights an important yet often understudied aspect of adjuvants.
RATIONALE:Several studies have suggested a role for the gut microbiota in inflammation and atherogenesis. A causal relation relationship between gut microbiota, inflammation, and atherosclerosis has ...not been explored previously.
OBJECTIVE:Here, we investigated whether a proinflammatory microbiota from Caspase1 (Casp1) mice accelerates atherogenesis in Ldlr mice.
METHOD AND RESULTS:We treated female Ldlr mice with antibiotics and subsequently transplanted them with fecal microbiota from Casp1 mice based on a cohousing approach. Autologous transplantation of fecal microbiota of Ldlr mice served as control. Mice were cohoused for 8 or 13 weeks and fed chow or high-fat cholesterol–rich diet. Fecal samples were collected, and factors related to inflammation, metabolism, intestinal health, and atherosclerotic phenotypes were measured. Unweighted Unifrac distances of 16S rDNA (ribosomal DNA) sequences confirmed the introduction of the Casp1 and Ldlr microbiota into Ldlr mice (referred to as Ldlr(Casp1) or Ldlr(Ldlr) mice). Analysis of atherosclerotic lesion size in the aortic root demonstrated a significant 29% increase in plaque size in 13-week high-fat cholesterol–fed Ldlr(Casp1) mice compared with Ldlr(Ldlr) mice. We found increased numbers of circulating monocytes and neutrophils and elevated proinflammatory cytokine levels in plasma in high-fat cholesterol–fed Ldlr(Casp1) compared with Ldlr(Ldlr) mice. Neutrophil accumulation in the aortic root of Ldlr(Casp1) mice was enhanced compared with Ldlr(Ldlr) mice. 16S-rDNA-encoding sequence analysis in feces identified a significant reduction in the short-chain fatty acid–producing taxonomies Akkermansia, Christensenellaceae, Clostridium, and Odoribacter in Ldlr(Casp1) mice. Consistent with these findings, cumulative concentrations of the anti-inflammatory short-chain fatty acids propionate, acetate and butyrate in the cecum were significantly reduced in 13-week high-fat cholesterol–fed Ldlr(Casp1) compared with Ldlr(Ldlr) mice.
CONCLUSIONS:Introduction of the proinflammatory Casp1 microbiota into Ldlr mice enhances systemic inflammation and accelerates atherogenesis.
Recent evidence demonstrates that the gut-microbiota can be considered as one of the major factors causing metabolic and cardiovascular diseases.
Pattern recognition receptors as well as ...antimicrobial peptides are a key factor in controlling the intestinal microbiota composition. Deficiencies in these genes lead to changes in the composition of the gut-microbiota, causing leakage of endotoxins into the circulation, and the development of low-grade chronic inflammation and insulin resistance. Dietary composition can also affect the microbiota: a diet rich in saturated fats allows the expansion of pathobionts that damage the intestinal epithelial cell layer and compromise its barrier function. In contrast, a diet high in fiber supports the microbiota to produce short-chain fatty acids, thereby promoting energy expenditure and protecting against inflammation and insulin resistance.
The interactions between the microbiota, innate immunity, and diet play an important role in controlling metabolic homeostasis. A properly functioning innate immune system, combined with a low-fat and high-fiber diet, is important in preventing dysbiosis and reducing the susceptibility to developing the metabolic syndrome and its associated cardiovascular diseases.
Abstract
Background
Recent advances in CRISPR-based diagnostics suggest that DETECTR, a combination of reverse-transcriptase loop-mediated isothermal amplification (RT-LAMP) and subsequent Cas12 ...bystander nuclease activation by amplicon-targeting ribonucleoprotein complexes, could be a faster and cheaper alternative to quantitative reverse-transcription polymerase chain reaction (qRT-PCR) without sacrificing sensitivity and/or specificity.
Methods
In this study, we compare DETECTR with qRT-PCR to diagnose coronavirus disease 2019 on 378 patient samples. Patient sample dilution assays suggest a higher analytical sensitivity of DETECTR compared with qRT-PCR; however, this was not confirmed in this large patient cohort, where we report 95% reproducibility between the 2 tests.
Results
These data showed that both techniques are equally sensitive in detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) providing additional value of DETECTR to the currently used qRT-PCR platforms. For DETECTR, different guide ribonucleic acids can be used simultaneously to obviate negative results due to mutations in N-gene. Lateral flow strips, suitable as a point-of-care test, showed a 100% correlation to the high-throughput DETECTR assay. More importantly, DETECTR was 100% specific for SARS-CoV-2 relative to other human coronaviruses.
Conclusions
Because there is no need for specialized equipment, DETECTR could be rapidly implemented as a complementary technically independent approach to qRT-PCR thereby increasing the testing capacity of medical microbiological laboratories and relieving the existent PCR platforms for routine non-SARS-CoV-2 diagnostic testing.
SARS-CoV-2 detection using DETECTR has 95% concordance with qRT-PCR. DETECTR is highly specific for SARS-CoV-2 and equally sensitive compared with qRT-PCR. DETECTR point-of-care and DETECTR high throughput represent independent alternatives to qRT-PCR platforms for SARS-CoV-2 detection.
Recent advances in CRISPR-based diagnostics suggest that DETECTR, a combination of isothermal reverse transcriptase loop mediated amplification (RT-LAMP) and subsequent Cas12 bystander nuclease ...activation by amplicon targeting ribonucleoprotein complexes, could be a faster and cheaper alternative to qRT-PCR without sacrificing sensitivity/specificity.
Here we compare DETECTR with qRT-PCR to diagnose COVID-19 on 378 patient samples.
Patient sample dilution assays suggest a higher analytical sensitivity of DETECTR compared to qRT-PCR, however, this was not confirmed in this large patient cohort, were we report 95% reproducibility between the two tests. These data showed that both techniques are equally sensitive in detecting SARS-CoV-2 providing additional value of DETECTR to the currently used qRT-PCR platforms. For DETECTR, different gRNAs can be used simultaneously to obviate negative results due to mutations in N-gene. Lateral flow strips, suitable as a point of care test (POCT), showed a 100% correlation to the high-throughput DETECTR assay. Importantly, DETECTR was 100% specific for SARS-CoV-2 relative to other human coronaviruses.
As there is no need for specialized equipment, DETECTR could be rapidly implemented as a complementary technically independent approach to qRT-PCR thereby increasing the testing capacity of medical microbiological laboratories and relieving the existent PCR-platforms for routine non-SARS-CoV-2 diagnostic testing.
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