Lipopolysaccharides

Lipopolysaccharide (LPS) from Gram-negative bacteria has been one of the most studied pathogen-associated molecular patterns triggering rapid inflammatory reactions. However, evidence shows that not all LPS molecules are proinflammatory ("bad"), and that "good" LPS from gut commensal bacteria exert immunomodulatory actions. The Limulus amebocyte lysis test commonly used to quantify LPS in circulation, only targets "bad" LPS, when not inactivated by plasma components. Use of other methods showed healthy subjects featuring elevated levels of LPS (suggesting predominance of "good" or inactive LPS in circulation). This review aims to summarize the evidence supporting the higher abundance of "good" LPS coming from gut commensals of healthy individuals and their potential impact in human health.

ObjectiveThis study aimed to investigate the associations between gut microbiota dysbiosis and alterations in cardiac function and to elucidate the underlying molecular mechanisms involved.MethodsEighteen rats were divided into a control group (n = 6), a heart failure (HF) group (n = 6), and a TAK-242 intervention group (n = 6). Cardiac function was assessed using small-animal echocardiography. Serum levels of brain natriuretic peptide (BNP) and inflammatory cytokines were measured by ELISA. Western blotting was used to detect phosphorylated p65 (P-p65) protein expression in myocardial tissue, and 16 S rRNA sequencing was performed to analyse the composition of the faecal gut microbiota.ResultsCompared with the control group, the heart failure group presented significant gut microbiota dysbiosis, characterized by increased relative abundance of Bacteroidetes and Spirochaetes and decreased relative abundance of Actinobacteria and Proteobacteria, along with reduced species diversity. The serum levels of lipopolysaccharide (LPS), IL-1β, IL-17, IL-6, and TNF-α were significantly elevated (P ConclusionGut microbiota dysbiosis exacerbates heart failure by activating myocardial inflammation through the LPS-TLR4/NF-κB signalling pathway. By modulating this pathway, TAK-242 improves cardiac function, suggesting its potential as a therapeutic target for heart failure.Clinical trial numberNot applicable.

Study questionWhat effect do toxins produced by bacterial vaginosis (BV) bacteria have on sperm function?Summary answerBV toxins dysregulate sperm capacitation and intracellular calcium homeostasis, and impair the ability of sperm to fertilize oocytes.What is known alreadyIn BV, which is linked to infertility, overgrowth of Prevotella and Gardnerella in the vagina is accompanied by elevated concentrations of the toxins lipopolysaccharide (LPS) and vaginolysin (VLY).Study design, size, durationThis was a laboratory study in which human semen samples were collected from consenting healthy donors with normal semen parameters. Mouse sperm samples were obtained from the caudal epididymis.Participants/materials, setting, methodsMotile mouse and human sperm were isolated via swim-up and treated under non-capacitating or capacitating conditions. LPS from Escherichia coli was commercially available. VLY was produced by cloning the Gardnerella VLY protein in the ClearColi expression system. Mouse sperm were pre-incubated in IVF medium with LPS or VLY and then co-cultured with ovulated cumulus-oocyte complexes. The effects of LPS and VLY on sperm motility and hyperactivation were assessed with computer-assisted sperm analysis. Effects on viability were assessed by Hoechst staining. Acrosomal exocytosis was assessed in sperm from transgenic Acr-eGFP mice and in human sperm stained with Pisum sativum agglutinin FITC. Intracellular calcium concentration was measured by using the calcium-sensitive dye Fluo-4 AM and fluorescence microscopy. The effects of LPS on sperm from CatSper knockout mice were assessed. Additionally, sperm were treated with a Toll-like receptor 4 (TLR4) antagonist and further exposed to LPS.Main results and the role of chanceExposure of mouse sperm to LPS or VLY significantly decreased IVF (P Large scale dataN/A.Limitations, reasons for cautionFirst, the commercially available LPS we used was isolated from Escherichia coli, rather than from the BV-associated bacteria Prevotella bivia. Second, we did not quantify the absolute sperm intracellular calcium concentration before or after LPS or VLY treatment. Third, all of our experiments were in vitro.Wider implications of the findingsThese studies suggest that BV-associated toxins contribute to infertility, in part, by impairing sperm capacitation and reducing their fertilizing ability.Study funding/competing interest(s)This work was supported by the National Institutes of Health (grant number R01 HD069631 to C.M.S.). The authors declare that they have no conflict of interest.

A role for the P2Y1 receptor (P2Y1R) in platelet-driven inflammation has been established using a pharmacological approach, limited to an acute 4 h time span. Nucleotide-structure P2Y1R antagonists have restricted experimental use due to inadequate pharmacokinetics, and an inability to decipher global versus cell specific effects in vivo. The creation of a conditional knock out (platelet) P2Y1R transgenic mouse model was designed to overcome these restrictions.A homozygous P2Y1 LoxP mouse colony was created using CRISPR/Cas9 technology, and crossed with a hemizygous P2Y1 LoxP with PF4-cre to provide offspring that are homozygous for P2Y1 LoxP flanked allele, and hemizygous for the PF4cre (platelet P2Y1−/−) and offspring homozygous for P2Y1 LoxP flanked allele, but non-carriers for PF4cre (control mice). Animals were intranasally administered LPS to induce pulmonary inflammation to assess the influence of phenotype on leukocyte recruitment.24 h post intranasal LPS administration; pulmonary neutrophil and platelet recruitment were significantly suppressed, despite the fact that neutrophils retained the ability to migrate to fMLP ex vivo. Circulating platelet and leukocyte numbers were not different between control and platelet P2Y1−/− animals. Tail bleeding times revealed the platelet P2Y1−/− mice had a severe bleeding phenotype.The platelet specific P2Y1−/− mouse model confirms the importance of platelet P2Y1R in the regulation of inflammatory responses. A 60–70% inhibition of leukocyte recruitment over an extended time period was observed compared to previous pharmacological studies. Platelet P2Y1−/− mice will help further elucidate the mechanisms by which P2Y1R regulate platelet activation during inflammation.