Molecular mechanisms of endotoxin activity

Controlled production of lipopolysaccharides increases immune activation in Salmonella treatments of cancer

Immunotherapies have revolutionized cancer treatment. These treatments rely on immune cell activation in tumours, which limits the number of patients that respond. Inflammatory molecules, like lipopolysaccharides (LPS), can activate innate immune cells, which convert tumour microenvironments from cold to hot, and increase therapeutic efficacy. However, systemic delivery of lipopolysaccharides (LPS) can induce cytokine storm. In this work, we developed immune-controlling Salmonella (ICS) that only produce LPS in tumours after colonization and systemic clearance. We tuned the expression of msbB, which controls production of immunogenic LPS, by optimizing its ribosomal binding sites and protein degradation tags. This genetic system induced a controllable inflammatory response and increased dendritic cell cross-presentation in vitro. The strong off state did not induce TNFα production and prevented adverse events when injected into mice. The accumulation of ICS in tumours after intravenous injection focused immune responses specifically to tumours. Tumour-specific expression of msbB increased infiltration of immune cells, activated monocytes and neutrophils, increased tumour levels of IL-6, and activated CD8 T cells in draining lymph nodes. These immune responses reduced tumour growth and increased mouse survival. By increasing the efficacy of bacterial anti-cancer therapy, localized production of LPS could provide increased options to patients with immune-resistant cancers.

The Effect of Enteric-Derived Lipopolysaccharides on Obesity

Endotoxin is a general term for toxic substances in Gram-negative bacteria, whose damaging effects are mainly derived from the lipopolysaccharides (LPS) in the cell walls of Gram-negative bacteria, and is a strong pyrogen. Obesity is a chronic, low-grade inflammatory condition, and LPS are thought to trigger and exacerbate it. The gut flora is the largest source of LPS in the body, and it is increasingly believed that altered intestinal microorganisms can play an essential role in the pathology of different diseases. Today, the complex axis linking gut flora to inflammatory states and adiposity has not been well elucidated. This review summarises the evidence for an interconnection between LPS, obesity, and gut flora, further expanding our understanding of LPS as a mediator of low-grade inflammatory disease and contributing to lessening the effects of obesity and related metabolic disorders. As well as providing targets associated with LPS, obesity, and gut flora, it is hoped that interventions that combine targets with gut flora address the individual differences in gut flora treatment.

New Strategies for Biocontrol of Bacterial Toxins and Virulence: Focusing on Quorum-Sensing Interference and Biofilm Inhibition

The overuse of antibiotics and the emergence of multiple-antibiotic-resistant pathogens are becoming a serious threat to health security and the economy. Reducing antimicrobial resistance requires replacing antibiotic consumption with more biocontrol strategies to improve the immunity of animals and humans. Probiotics and medicinal plants have been used as alternative treatments or preventative therapies for a variety of diseases caused by bacterial infections. Therefore, we reviewed some of the anti-virulence and bacterial toxin-inhibiting strategies that are currently being developed; this review covers strategies focused on quenching pathogen quorum sensing (QS) systems, the disruption of biofilm formation and bacterial toxin neutralization. It highlights the probable mechanism of action for probiotics and medicinal plants. Although further research is needed before a definitive statement can be made on the efficacy of any of these interventions, the current literature offers new hope and a new tool in the arsenal in the fight against bacterial virulence factors and bacterial toxins.

Effects of a High-Concentrate Diet on the Blood Parameters and Liver Transcriptome of Goats

The objective of this study was to determine the effect of high-concentrate diets on the blood parameters and liver transcriptome of goats. Eighteen goats were allocated into three dietary treatments: the high level of concentrate (HC) group, the medium level of concentrate (MC) group, and the low level of concentrate (LC) group. The blood parameters and pathological damage of the gastrointestinal tract and liver tissues were measured. In hepatic portal vein blood, HC showed higher LPS, VFAs, and LA; in jugular vein blood, no significant differences in LPS, VFAs, and LA were recorded among groups (p > 0.05). Compared to the LC and MC groups, the HC group showed significantly increased interleukin (IL)-1β, IL-10, TNF-α, and diamine oxidase in jugular vein blood (p < 0.05). Liver transcriptome analysis discovered a total of 1269 differentially expressed genes (DEGs) among the three groups and most of them came from the HC vs. LC group. There were 333 DEGs up-regulated and 608 down-regulated in the HC group compared to the LC group. The gene ontology enrichment analysis showed that these DEGs were mainly focused on the regulation of triacylglycerol catabolism, lipoprotein particle remodeling, and cholesterol transport. The Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that the liver of the HC group enhanced the metabolism of nutrients such as VFAs through the activation of AMPK and other signaling pathways and enhanced the clearance and detoxification of LPS by activating the toll-like receptor signaling pathway. A high-concentrate diet (HCD) can significantly promote the digestion of nutrients; the liver enhances the adaptability of goats to an HCD by regulating the expression of genes involved in nutrient metabolism and toxin clearance.

Bacteriostatic Effects of Yujin Powder and Its Components on Clinical Isolation of Multidrug-Resistant Avian Pathogenic Escherichia coli

Escherichia coli is one of the most common pathogenic bacteria in diarrheal chickens, leading to serious economic losses in the poultry industry. The limited effect of antibiotics on antibiotic-resistant E. coli makes this bacterium a potential threat to human health. Yujin powder (YJP) has been reported as an agent that releases the symptoms caused by E. coli for a long time. The objective of this study is to investigate the effect of Yujin powder (YJP) and its components, Scutellariae Radix (SR) and Baicalin (Bac), anti-against multi-drug-resistant E. coli in vitro and in vivo. A multi-drug-resistant bacteria was isolated and identified from a clinical diarrheal chick. Then, the anti-bacterial effects of drugs were assessed in vitro and in vivo by analyzing the bacteria loads of organs, the levels of endotoxin, TNF-α, IL-1β, and IL-6 of the serum. Results found that the pathogenic E. coli was resistant to 19 tested antibiotics. YJP, SR, and Bac could directly inhibit the growth of this strain at high concentrations in vitro, and presents obvious anti-bacterial effects by reducing the bacterial loads, the release of endotoxin, and inflammation in vivo, which was much more effective than the resistant antibiotic ciprofloxacin. This study demonstrates that those natural medicines have the potential to be used as novel treatments to treat the disease caused by this isolated MDREC strain.

Escherichia coli-Derived Outer Membrane Vesicles Relay Inflammatory Responses to Macrophage-Derived Exosomes

Extracellular vesicles are considered to be an inflammatory factor in several acute and chronic inflammatory diseases. The present study shows that exosomes from macrophages (Mφ) infected with live Escherichia coli induced secretion of proinflammatory factors by uninfected Mφ. Inflammatory responses induced by exosomes derived from Mφ infected with heat-inactivated E. coli or lipopolysaccharide were significantly weaker than those elicited by outer membrane vesicles (OMVs) released from live E. coli. Proteome analysis of exosomes from Mφ infected with live or heat-inactivated E. coli revealed that E. coli proteins OmpA, GroL1, DegP, CirA, and FepA are candidate triggers of exosome-mediated inflammatory responses. OMVs from a cirA-deleted strain suppressed exosome-mediated inflammatory responses by uninfected Mφ. The C terminus of the CirA protein (residues 158 to 633), which was relayed from E. coli-derived OMV to Mφ-derived exosomes, promoted exosome-mediated inflammatory responses by uninfected Mφ. These results suggest an alternative mechanism by which extracellular vesicles from E. coli OMV-elicited Mφ transmit proinflammatory responses to uninfected Mφ. IMPORTANCE Recently, extracellular membrane vesicles (EVs) were regarded as drivers that carry cargo such as proteins, lipids, metabolites, RNA, and DNA for intracellular signaling transduction. Mammalian cells release various types of EVs, including microvesicles shed from the plasma membrane, exosomes from endosomes, apoptotic bodies, and others. EVs have been reported to mediate inflammatory signals between mammalian cells. In addition, bacteria are also known to release EVs to carry various bacterial factors. In this study, we show that bacterial EVs lead host mammalian cells to release stimulatory EVs that enhance inflammatory responses. Our results provide a novel example that bacterial EVs transduce biological signals to mammalian EVs.

Highly Sensitive Electrochemical Endotoxin Sensor Based on Redox Cycling Using an Interdigitated Array Electrode Device

The Limulus amebocyte lysate (LAL) reaction-based assay, the most commonly used endotoxin detection method, requires a skilled technician. In this study, to develop an easy-to-use and highly sensitive endotoxin sensor, we created an electrochemical endotoxin sensor by using an interdigitated array electrode (IDAE) device with advantages of amplifiable signals via redox cycling and portability. We added Boc-Leu-Gly-Arg-p-aminophenol (LGR-pAP) as an electrochemical substrate for an LAL reaction and detected p-aminophenol (pAP) released from LGR-pAP as a product of an endotoxin-induced LAL reaction via an IDAE device. The IDAE device showed a great redox cycling efficiency of 79.8%, and a 4.79-fold signal amplification rate. Then, we confirmed that pAP was detectable in the presence of LGR-pAP through chronoamperometry with the potential of the anode stepped from -0.3 to 0.5 V vs. Ag/AgCl while the cathode was biased at -0.3 V vs. Ag/AgCl. Then, we performed an endotoxin assay by using the IDAE device. Our endotoxin sensor detected as low as 0.7 and 1.0 endotoxin unit/L after the LAL reaction for 1 h and 45 min, respectively, and these data were within the cut-off value for ultrapure dialysis fluid. Therefore, our highly sensitive endotoxin sensor is useful for ensuring medical safety.

Modification of bacterial cells for in vivo remotely guided systems

It was shown recently that bacterial strains, which can act specifically against malignant cells, can be used efficiently in cancer therapy. Many appropriate bacterial strains are either pathogenic or invasive and there is a substantial shortage of methods with which to monitor in vivo the distribution of bacteria used in this way. Here, it is proposed to use a Layer-by-Layer (LbL) approach that can encapsulate individual bacterial cells with fluorescently labeled polyelectrolytes (PE)s and magnetite nanoparticles (NP)s. The NP enable remote direction in vivo to the site in question and the labeled shells in the far-red emission spectra allow non-invasive monitoring of the distribution of bacteria in the body. The magnetic entrapment of the modified bacteria causes the local concentration of the bacteria to increase by a factor of at least 5. The PEs create a strong barrier, and it has been shown in vitro experiments that the division time of bacterial cells coated in this way can be regulated, resulting in control of their invasion into tissues. That animals used in the study survived and did not suffer septic shock, which can be attributed to PE capsules that prevent release of endotoxins from bacterial cells.

Oxidative stress and immune response of hepatopancreas in Chinese mitten crab Eriocheir sinensis under lipopolysaccharide challenge

Chinese mitten crab (Eriocheir sinensis; H. Milne Edwards, 1853) is one of the important farmed crustaceans in China. Lipopolysaccharide (LPS), as a harmful factor, is prone to occur during the farming process of crabs. Aiming to test the hypothesis that damage degrees of the hepatopancreas in E. sinensis is correlated to LPS concentrations, in this study, E. sinensis were injected with LPS (50 μg/kg, and 500 μg/kg) and analyzed for the activity of antioxidant and immune-related enzymes, immune-related gene expression, and histopathological of hepatopancreas. As result, the hepatopancreas of E. sinensis immune-related genes, i.e., Dorsal, HSP90, Toll2, TLRs, Tube, and proPO, were significantly affected by LPS challenge. Among immune-related genes, Dorsal and proPO might play key roles in combating the LPS challenge. The activity of CAT gradually decreased with the increase of time, and the total antioxidant capacity was decreased after LPS challenge, indicating the inhibition of LPS on the antioxidant system. Interestingly, the decreasing trend of AKP and ACP activity suggested the immune system of crabs was affected by LPS challenge. The hepatopancreas section showed that the damage degree of hepatopancreas was different under the challenge of LPS with different concentrations, and the damage degree was proportional to the concentration. Our findings provide useful information for understanding the mechanism of hepatopancreas injury of E. sinensis induced by LPS infection.

Therapeutic Targeting of TLR4 for Inflammation, Infection, and Cancer: A Perspective for Disaccharide Lipid A Mimetics

The Toll-like receptor 4 (TLR4) signaling pathway plays a central role in the prompt defense against infectious challenge and provides immediate response to Gram-negative bacterial infection. The TLR4/MD-2 complex can sense and respond to various pathogen-associated molecular patterns (PAMPs) with bacterial lipopolysaccharide (LPS) being the most potent and the most frequently occurring activator of the TLR4-mediated inflammation. TLR4 is believed to be both a friend and foe since improperly regulated TLR4 signaling can result in the overactivation of immune responses leading to sepsis, acute lung injury, or pathologic chronic inflammation involved in cancer and autoimmune disease. TLR4 is also considered a legitimate target for vaccine adjuvant development since its activation can boost the adaptive immune responses. The dual action of the TLR4 complex justifies the efforts in the development of both TLR4 antagonists as antisepsis drug candidates or remedies for chronic inflammatory diseases and TLR4 agonists as vaccine adjuvants or immunotherapeutics. In this review, we provide a brief overview of the biochemical evidences for possible pharmacologic applications of TLR4 ligands as therapeutics and report our systematic studies on the design, synthesis, and immunobiological evaluation of carbohydrate-based TLR4 antagonists with nanomolar affinity for MD-2 as well as disaccharide-based TLR4 agonists with picomolar affinity for the TLR4/MD-2 complex.

Plasma Membrane-Associated Proteins Identified in Arabidopsis Wild Type, lbr2-2 and bak1-4 Mutants Treated with LPSs from Pseudomonas syringae and Xanthomonas campestris

Plants recognise bacterial microbe-associated molecular patterns (MAMPs) from the environment via plasma membrane (PM)-localised pattern recognition receptor(s) (PRRs). Lipopolysaccharides (LPSs) are known as MAMPs from gram-negative bacteria that are most likely recognised by PRRs and trigger defence responses in plants. The Arabidopsis PRR(s) and/or co-receptor(s) complex for LPS and the associated defence signalling remains elusive. As such, proteomic identification of LPS receptors and/or co-receptor complexes will help to elucidate the molecular mechanisms that underly LPS perception and defence signalling in plants. The Arabidopsis LPS-binding protein (LBP) and bactericidal/permeability-increasing protein (BPI)-related-2 (LBR2) have been shown to recognise LPS and trigger defence responses while brassinosteroid insensitive 1 (BRI1)-associated receptor kinase 1 (BAK1) acts as a co-receptor for several PRRs. In this study, Arabidopsis wild type (WT) and T-DNA knock out mutants (lbr2-2 and bak1-4) were treated with LPS chemotypes from Pseudomonas syringae pv. tomato DC3000 (Pst) and Xanthomonas campestris pv. campestris 8004 (Xcc) over a 24 h period. The PM-associated protein fractions were separated by liquid chromatography and analysed by tandem mass spectrometry (LC-MS/MS) followed by data analysis using Byonic^TM software. Using Gene Ontology (GO) for molecular function and biological processes, significant LPS-responsive proteins were grouped according to defence and stress response, perception and signalling, membrane transport and trafficking, metabolic processes and others. Venn diagrams demarcated the MAMP-responsive proteins that were common and distinct to the WT and mutant lines following treatment with the two LPS chemotypes, suggesting contributions from differential LPS sub-structural moieties and involvement of LBR2 and BAK1 in the LPS-induced MAMP-triggered immunity (MTI). Moreover, the identification of RLKs and RLPs that participate in other bacterial and fungal MAMP signalling proposes the involvement of more than one receptor and/or co-receptor for LPS perception as well as signalling in Arabidopsis defence responses.

Bacterial lipopolysaccharide induces settlement and metamorphosis in a marine larva

New surfaces in the sea are quickly populated by dense communities of invertebrate animals, whose establishment and maintenance require site-specific settlement of larvae from the plankton. Larvae selectively settle in sites where they can metamorphose and thrive largely due to inductive cues from bacteria residing on these surfaces. However, the nature of the cues used to identify “right places” has remained enigmatic. Here, we demonstrate that lipopolysaccharide, the main component of the outer membrane of Gram-negative bacteria from the bacterium Cellulophaga lytica , induces metamorphosis for a marine worm. We then discuss the likelihood that lipopolysaccharide provides the variation necessary to explain settlement site selectivity for many of the bottom-living invertebrate animals that metamorphose in response to bacterial biofilms.

How larvae of the many phyla of marine invertebrates find places appropriate for settlement, metamorphosis, growth, and reproduction is an enduring question in marine science. Biofilm-induced metamorphosis has been observed in marine invertebrate larvae from nearly every major marine phylum. Despite the widespread nature of this phenomenon, the mechanism of induction remains poorly understood. The serpulid polychaete Hydroides elegans is a well established model for investigating bacteria-induced larval development. A broad range of biofilm bacterial species elicit larval metamorphosis in H. elegans via at least two mechanisms, including outer membrane vesicles (OMVs) and complexes of phage-tail bacteriocins. We investigated the interaction between larvae of H. elegans and the inductive bacterium Cellulophaga lytica , which produces an abundance of OMVs but not phage-tail bacteriocins. We asked whether the OMVs of C. lytica induce larval settlement due to cell membrane components or through delivery of specific cargo. Employing a biochemical structure–function approach with a strong ecological focus, the cells and OMVs produced by C. lytica were interrogated to determine the class of the inductive compounds. Here, we report that larvae of H. elegans are induced to metamorphose by lipopolysaccharide produced by C. lytica . The widespread prevalence of lipopolysaccharide and its associated taxonomic and structural variability suggest it may be a broadly employed cue for bacterially induced larval settlement of marine invertebrates.

Single-cell transcriptomic and chromatin accessibility analyses of dairy cattle peripheral blood mononuclear cells and their responses to lipopolysaccharide

Background

Gram-negative bacteria are important pathogens in cattle, causing severe infectious diseases, including mastitis. Lipopolysaccharides (LPS) are components of the outer membrane of Gram-negative bacteria and crucial mediators of chronic inflammation in cattle. LPS modulations of bovine immune responses have been studied before. However, the single-cell transcriptomic and chromatin accessibility analyses of bovine peripheral blood mononuclear cells (PBMCs) and their responses to LPS stimulation were never reported.

Results

We performed single-cell RNA sequencing (scRNA-seq) and single-cell sequencing assay for transposase-accessible chromatin (scATAC-seq) in bovine PBMCs before and after LPS treatment and demonstrated that seven major cell types, which included CD4 T cells, CD8 T cells, and B cells, monocytes, natural killer cells, innate lymphoid cells, and dendritic cells. Bioinformatic analyses indicated that LPS could increase PBMC cell cycle progression, cellular differentiation, and chromatin accessibility. Gene analyses further showed significant changes in differential expression, transcription factor binding site, gene ontology, and regulatory interactions during the PBMC responses to LPS. Consistent with the findings of previous studies, LPS induced activation of monocytes and dendritic cells, likely through their upregulated TLR4 receptor. NF-κB was observed to be activated by LPS and an increased transcription of an array of pro-inflammatory cytokines, in agreement that NF-κB is an LPS-responsive regulator of innate immune responses. In addition, by integrating LPS-induced differentially expressed genes (DEGs) with large-scale GWAS of 45 complex traits in Holstein, we detected trait-relevant cell types. We found that selected DEGs were significantly associated with immune-relevant health, milk production, and body conformation traits.

Conclusion

This study provided the first scRNAseq and scATAC-seq data for cattle PBMCs and their responses to the LPS stimulation to the best of our knowledge. These results should also serve as valuable resources for the future study of the bovine immune system and open the door for discoveries about immune cell roles in complex traits like mastitis at single-cell resolution.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08562-0.

Targeting the Toll-like receptor pathway as a therapeutic strategy for neonatal infection

Toll-like receptors (TLRs) are crucial transmembrane receptors that form part of the innate immune response. They play a role in the recognition of various microorganisms and their elimination from the host. TLRs have been proposed as vital immunomodulators in the regulation of multiple neonatal stressors that extend beyond infection such as oxidative stress and pain. The immune system is immature at birth and takes some time to become fully established. As such, babies are especially vulnerable to sepsis at this early stage of life. Findings suggest a gestational age-dependent increase in TLR expression. TLRs engage with accessory and adaptor proteins to facilitate recognition of pathogens and their activation of the receptor. TLRs are generally upregulated during infection and promote the transcription and release of proinflammatory cytokines. Several studies report that TLRs are epigenetically modulated by chromatin changes and promoter methylation upon bacterial infection that have long-term influences on immune responses. TLR activation is reported to modulate cardiorespiratory responses during infection and may play a key role in driving homeostatic instability observed during sepsis. Although complex, TLR signaling and downstream pathways are potential therapeutic targets in the treatment of neonatal diseases. By reviewing the expression and function of key Toll-like receptors, we aim to provide an important framework to understand the functional role of these receptors in response to stress and infection in premature infants.

Shotgun Bacterial Lipid A Analysis Using Routine MALDI-TOF Mass Spectrometry

Detection of bacterial lipids and particularly the lipid A, the lipid anchor of the lipopolysaccharide, can be very challenging and requires a certain level of expertise. Here, this chapter describes a straightforward and simple method for the analysis of bacterial lipid A. In addition, such approach, lipid fingerprint, has the potential to be applied to other bacteria such as mycobacteria.

Intravenous administration of LPS activates the kynurenine pathway in healthy male human subjects: a prospective placebo-controlled cross-over trial

Background

Administration of lipopolysaccharide (LPS) from Gram-negative bacteria, also known as the human endotoxemia model, is a standardized and safe model of human inflammation. Experimental studies have revealed that peripheral administration of LPS leads to induction of the kynurenine pathway followed by depressive-like behavior and cognitive dysfunction in animals. The aim of the present study is to investigate how acute intravenous LPS administration affects the kynurenine pathway in healthy male human subjects.

Methods

The present study is a prospective, single-blinded, randomized, placebo-controlled cross-over study to investigate the effects of intravenously administered LPS (Escherichia coli O113, 2 ng/kg) on tryptophan and kynurenine metabolites over 48 h and their association with interleukin-6 (IL-6) and C-reactive protein (CRP). The study included 10 healthy, non-smoking men (18–40 years) free from medication. Statistical differences in tryptophan and kynurenine metabolites as well as associations with IL-6 and CRP in LPS and placebo treated subjects were assessed with linear mixed-effects models.

Results

Systemic injection of LPS was associated with significantly lower concentrations of plasma tryptophan and kynurenine after 4 h, as well as higher concentrations of quinolinic acid (QUIN) after 48 h compared to the placebo injection. No differences were found in kynurenic acid (KYNA) or picolinic acid plasma concentrations between LPS or placebo treatment. The KYNA/kynurenine ratio peaked at 6 h post LPS injection while QUIN/kynurenine maintained significantly higher from 3 h post LPS injection until 24 h. The kynurenine/tryptophan ratio was higher at 24 h and 48 h post LPS treatment. Finally, we report an association between the kynurenine/tryptophan ratio and CRP.

Conclusions

Our findings strongly support the concept that an inflammatory challenge with LPS induces the kynurenine pathway in humans, activating both the neurotoxic (QUIN) and neuroprotective (KYNA) branch of the kynurenine pathway.

Trial registration

This study is based on a study registered at ClinicalTrials.gov, NCT03392701. Registered 21 December 2017.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02196-x.

Endotoxin contamination of engineered nanomaterials: Overcoming the hurdles associated with endotoxin testing

Nanomaterials are highly susceptible to endotoxin contamination due their large surface-to-volume ratios and endotoxins propensity to associate readily to hydrophobic and cationic surfaces. Additionally, the stability of endotoxin ensures it cannot be removed efficiently through conventional sterilization techniques such as autoclaving and ionizing radiation. In recent times, the true significance of this hurdle has come to light with multiple reports from the United States Nanotechnology Characterization Laboratory, in particular, along with our own experiences of endotoxin testing from multiple Horizon 2020-funded projects which highlight the importance of this issue for the clinical translation of nanomaterials. Herein, we provide an overview on the topic of endotoxin contamination of nanomaterials intended for biomedical applications. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

The Microbiota and the Gut-Brain Axis in Controlling Food Intake and Energy Homeostasis

Obesity currently represents a major societal and health challenge worldwide. Its prevalence has reached epidemic proportions and trends continue to rise, reflecting the need for more effective preventive measures. Hypothalamic circuits that control energy homeostasis in response to food intake are interesting targets for body-weight management, for example, through interventions that reinforce the gut-to-brain nutrient signalling, whose malfunction contributes to obesity. Gut microbiota-diet interactions might interfere in nutrient sensing and signalling from the gut to the brain, where the information is processed to control energy homeostasis. This gut microbiota-brain crosstalk is mediated by metabolites, mainly short chain fatty acids, secondary bile acids or amino acids-derived metabolites and subcellular bacterial components. These activate gut-endocrine and/or neural-mediated pathways or pass to systemic circulation and then reach the brain. Feeding time and dietary composition are the main drivers of the gut microbiota structure and function. Therefore, aberrant feeding patterns or unhealthy diets might alter gut microbiota-diet interactions and modify nutrient availability and/or microbial ligands transmitting information from the gut to the brain in response to food intake, thus impairing energy homeostasis. Herein, we update the scientific evidence supporting that gut microbiota is a source of novel dietary and non-dietary biological products that may beneficially regulate gut-to-brain communication and, thus, improve metabolic health. Additionally, we evaluate how the feeding time and dietary composition modulate the gut microbiota and, thereby, the intraluminal availability of these biological products with potential effects on energy homeostasis. The review also identifies knowledge gaps and the advances required to clinically apply microbiome-based strategies to improve the gut-brain axis function and, thus, combat obesity.

Neurotoxin-Induced Rodent Models of Parkinson's Disease: Benefits and Drawbacks

Parkinson's disease (PD), the second most common neurodegenerative disorder, is characterized by cardinal motor impairments, including akinesia and tremor, as well as by a host of non-motor symptoms, including both autonomic and cognitive dysfunction. PD is associated with a death of nigral dopaminergic neurons, as well as the pathological spread of Lewy bodies, consisting predominantly of the misfolded protein alpha-synuclein. To date, only symptomatic treatments, such as levodopa, are available, and trials aiming to cure the disease, or at least halt its progression, have not been successful. Wong et al. (2019) suggested that the lack of effective therapy against neurodegeneration in PD might be attributed to the fact that the molecular mechanisms standing behind the dopaminergic neuronal vulnerability are still a major scientific challenge. Understanding these molecular mechanisms is critical for developing effective therapy. Thirty-five years ago, Calne and William Langston (1983) raised the question of whether biological or environmental factors precipitate the development of PD. In spite of great advances in technology and medicine, this question still lacks a clear answer. Only 5-15% of PD cases are attributed to a genetic mutation, with the majority of cases classified as idiopathic, which could be linked to exposure to environmental contaminants. Rodent models play a crucial role in understanding the risk factors and pathogenesis of PD. Additionally, well-validated rodent models are critical for driving the preclinical development of clinically translatable treatment options. In this review, we discuss the mechanisms, similarities and differences, as well as advantages and limitations of different neurotoxin-induced rat models of PD. In the second part of this review, we will discuss the potential future of neurotoxin-induced models of PD. Finally, we will briefly demonstrate the crucial role of gene-environment interactions in PD and discuss fusion or dual PD models. We argue that these models have the potential to significantly further our understanding of PD.

Identification and Characterization of Zebrafish Tlr4 Coreceptor Md-2

The zebrafish (Danio rerio) is a powerful model organism for studies of the innate immune system. One apparent difference between human and zebrafish innate immunity is the cellular machinery for LPS sensing. In amniotes, the protein complex formed by TLR4 and myeloid differentiation factor 2 (Tlr4/Md-2) recognizes the bacterial molecule LPS and triggers an inflammatory response. It is believed that zebrafish have neither Md-2 nor Tlr4; Md-2 has not been identified outside of amniotes, whereas the zebrafish tlr4 genes appear to be paralogs, not orthologs, of amniote TLR4s We revisited these conclusions. We identified a zebrafish gene encoding Md-2, ly96 Using single-cell RNA sequencing, we found that ly96 is transcribed in cells that also transcribe genes diagnostic for innate immune cells, including the zebrafish tlr4-like genes. In larval zebrafish, ly96 is expressed in a small number of macrophage-like cells. In a functional assay, zebrafish Md-2 and Tlr4ba form a complex that activates NF-κB signaling in response to LPS. In larval zebrafish ly96 loss-of-function mutations perturbed LPS-induced cytokine production but gave little protection against LPS toxicity. Finally, by analyzing the genomic context of tlr4 genes in 11 jawed vertebrates, we found that tlr4 arose prior to the divergence of teleosts and tetrapods. Thus, an LPS-sensitive Tlr4/Md-2 complex is likely an ancestral feature shared by mammals and zebrafish, rather than a de novo invention on the tetrapod lineage. We hypothesize that zebrafish retain an ancestral, low-sensitivity Tlr4/Md-2 complex that confers LPS responsiveness to a specific subset of innate immune cells.

Lipopolysaccharide triggers different transcriptional signatures in taurine and indicine cattle macrophages: Reactive oxygen species and potential outcomes to the development of immune response to infections

Macrophages are classified upon activation as classical activated M1 and M2 anti-inflammatory regulatory populations. This macrophage polarization is well characterized in humans and mice, but M1/M2 profile in cattle has been far less explored. Bos primigenius taurus (taurine) and Bos primigenius indicus (indicine) cattle display contrasting levels of resistance to infection and parasitic diseases such as C57BL/6J and Balb/c murine experimental models of parasite infection outcomes based on genetic background. Thus, we investigated the differential gene expression profile of unstimulated and LPS stimulated monocyte-derived macrophages (MDMs) from Holstein (taurine) and Gir (indicine) breeds using RNA sequencing methodology. For unstimulated MDMs, the contrast between Holstein and Gir breeds identified 163 Differentially Expressed Genes (DEGs) highlighting the higher expression of C-C chemokine receptor type five (CCR5) and BOLA-DQ genes in Gir animals. LPS-stimulated MDMs from Gir and Holstein animals displayed 1,257 DEGs enriched for cell adhesion and inflammatory responses. Gir MDMs cells displayed a higher expression of M1 related genes like Nitric Oxide Synthase 2 (NOS2), Toll like receptor 4 (TLR4), Nuclear factor NF-kappa-B 2 (NFKB2) in addition to higher levels of transcripts for proinflammatory cytokines, chemokines, complement factors and the acute phase protein Serum Amyloid A (SAA). We also showed that gene expression of inflammatory M1 population markers, complement and SAA genes was higher in Gir in buffy coat peripheral cells in addition to nitric oxide concentration in MDMs supernatant and animal serum. Co-expression analyses revealed that Holstein and Gir animals showed different transcriptional signatures in the MDMs response to LPS that impact on cell cycle regulation, leukocyte migration and extracellular matrix organization biological processes. Overall, the results suggest that Gir animals show a natural propensity to generate a more pronounced M1 inflammatory response than Holstein, which might account for a faster immune response favouring resistance to many infection diseases.

Activation of Gingival Fibroblasts by Bacterial Cyclic Dinucleotides and Lipopolysaccharide

Human gingival fibroblasts (HGFs) recognize microbe-associated molecular patterns (MAMPs) and respond with inflammatory proteins. Simultaneous impacts of bacterial cyclic di-guanosine monophosphate (c-di-GMP), cyclic di-adenosine monophosphate (c-di-AMP), and lipopolysaccharide (LPS) on gingival keratinocytes have been previously demonstrated, but the effects of these MAMPs on other periodontal cell types, such as gingival fibroblasts, remain to be clarified. The present aim was to examine the independent and combined effects of these cyclic dinucleotides and LPS on interleukin (IL) and matrix metalloproteinase (MMP) response of HGFs. The cells were incubated with c-di-GMP and c-di-AMP, either in the presence or absence of Porphyromonas gingivalis LPS, for 2 h and 24 h. The levels of IL-8, -10, and -34, and MMP-1, -2, and -3 secreted were measured by the Luminex technique. LPS alone or together with cyclic dinucleotides elevated IL-8 levels. IL-10 levels were significantly increased in the presence of c-di-GMP and LPS after 2 h but disappeared after 24 h of incubation. Concurrent treatment of c-di-AMP and LPS elevated MMP-1 levels, whereas c-di-GMP with LPS suppressed MMP-2 levels but increased MMP-3 levels. To conclude, we produce evidence that cyclic dinucleotides interact with LPS-mediated early response of gingival fibroblasts, while late cellular response is mainly regulated by LPS.

Oral exposure of pigs to the mycotoxin deoxynivalenol does not modulate the hepatic albumin synthesis during a LPS-induced acute-phase reaction

The sensitivity of pigs to deoxynivalenol (DON) might be influenced by systemic inflammation (SI) which impacts liver. Besides following acute-phase proteins, our aim was to investigate both the hepatic fractional albumin (ALB) synthesis rate (FSR) and the ALB concentration as indicators of ALB metabolism in presence and absence of SI induced by LPS via pre- or post-hepatic venous route. Each infusion group was pre-conditioned either with a control diet (CON, 0.12 mg DON/kg diet) or with a DON-contaminated diet (DON, 4.59 mg DON/kg diet) for 4 wk. A depression of ALB FSR was observed 195 min after LPS challenge, independent of feeding group or LPS application route, which was not paralleled by a down-regulated ALB mRNA expression but by a reduced availability of free cysteine. The drop in ALB FSR only partly explained the plasma ALB concentrations which were more depressed in the DON-pre-exposed groups, suggesting that ALB levels are influenced by further mechanisms. The abundances of haptoglobin, C-reactive protein, serum amyloid A, pig major acute-phase protein, fibrinogen and LPS-binding protein mRNA were up-regulated upon LPS stimulation but not accompanied by increases in the plasma concentrations of these proteins, pointing at an imbalance between synthesis and consumption.

The Impact of Prophylactic Lacosamide on LPS-Induced Neuroinflammation in Aged Rats

Sepsis-induced central nervous system damage is called sepsis-associated encephalopathy (SAE). In addition to neuroinflammation, oxidative stress and apoptosis act in the development of SAE. In the current study, we evaluated the protective effects of lacosamide (LCM) on neuroinflammation induced by lipopolysaccharide (LPS). Twenty-four Wistar albino rats were divided into 3 groups as controls, LPS group (5 mg/kg i.p.), and LPS plus LCM group (5 mg/kg i.p and 40 mg/kg i.p, respectively). In the rat brain, LPS-induced tissue damage was revealed histopathologically as hyperemia and microhemorrhages. LCM pretreatment ameliorated these histopathological changes. LPS decreased brain TAS levels and significantly increased MDA, CRP, HSP, IL-1β, and TNF-α expressions in the cortex, hippocampus, and cerebellum. Western analysis revealed increased brain tissue levels of TNF-α, NF-Kβ, and caspase-3 following LPS. Prophylactic LCM treatment reversed these parameters including oxidative stress, inflammation, and apoptosis in the cortex, hippocampus, and cerebellum.

Saturated Fatty Acids in Obesity-Associated Inflammation

Obesity is a major risk factor for the development of various pathological conditions including insulin resistance, diabetes, cardiovascular diseases, and non-alcoholic fatty liver disease (NAFLD). Central to these conditions is obesity-associated chronic low-grade inflammation in many tissues including adipose, liver, muscle, kidney, pancreas, and brain. There is increasing evidence that saturated fatty acids (SFAs) increase the phosphorylation of MAPKs, enhance the activation of transcription factors such as nuclear factor (NF)-κB, and elevate the expression of inflammatory genes. This paper focuses on the mechanisms by which SFAs induce inflammation. SFAs may induce the expression inflammatory genes via different pathways including toll-like receptor (TLR), protein kinase C (PKC), reactive oxygen species (ROS), NOD-like receptors (NLRs), and endoplasmic reticulum (ER) stress. These findings suggest that SFAs act as an important link between obesity and inflammation.

Application of a Recombinant Three-Factor Chromogenic Reagent, PyroSmart, for Bacterial Endotoxins Test Filed in the Pharmacopeias

Assays using lysate reagents prepared from horseshoe crab hemocyte extract (limulus amoebocyte lysate, LAL) are commonly and widely used to detect and measure endotoxin in parenteral drugs and medical devices. However, lysate reagents suffer from lot-to-lot variations leading to possible fluctuations in testing. Also, this continued usage of lysate reagents leads to the possible decline of the horseshoe crab population. Recently, a new recombinant chromogenic reagent, PyroSmart, consisting of three recombinant factors was introduced to the market. There are now three recombinant products; two with recombinant factor C reagents and PyroSmart with the complete recombinant LAL system. We evaluated the applicability of the reagent to the harmonized bacterial endotoxins test in the United States, European and Japanese pharmacopeias. The recombinant product showed equivalent potency of thirteen endotoxins from different bacterial strains to conventional chromogenic lysate reagents as long as their assay modes are identical. All analytical characteristics or assay parameters of the reagent satisfied the acceptance criteria which are set for the use for the bacterial endotoxins test filed in the pharmacopeias. All of 109 parenteral drugs tested can be measured with PyroSmart within respective maximum allowable dilutions. The lot-to-lot variation in recovery of endotoxin added in the parenteral drugs for PyroSmart was equal to or less than those of six limulus lysate reagents. In conclusion, the present study suggests that the recombinant reagent, PyroSmart, provide a good alternative to the LAL reagents with better lot-to-lot variation.

Reduced Trichomonas vaginalis viability in mice pretreated with parasite DNA

Trichomonas vaginalis is an extracellular parasite that colonizes the human urogenital tract leading to trichomoniasis, the most common sexually-transmitted non-viral disease worldwide. The immune response plays a critical role in the host defense against this parasite. Trichomonas' DNA contains unmethylated CpG motifs (CpGDNA) that in other microorganisms act as modulators of the immune response. However, the molecular mechanisms responsible for CpGDNA immune modulation are still unclear. As macrophages participate in the first line of defense against infection, we investigated the type of immune response of murine macrophages to T. vaginalis DNA (TvDNA). We observed high expression of the proinflammatory cytokines IL-6 and IL-12p40 in macrophages stimulated with TvDNA. In contrast, the anti-inflammatory response, assessed by IL-10 and IL-13 mRNA expression was delayed. This suggests that the immune response induced by TvDNA is modulated through cytokine production, mediated partly by NADPH-oxidase activity, as TvDNA induced reactive species of oxygen production and a rounded morphology in macrophages indicative of an M1 phenotype. Furthermore, infected mice pretreated with TvDNA displayed persistent vulvar inflammation and decreased parasite viability consistent with higher proinflammatory cytokine levels during infection compared to untreated mice. Overall, our findings suggest that TvDNA pretreatment modulates the immune response favouring parasite elimination.

Regulation of gingival epithelial cytokine response by bacterial cyclic dinucleotides

BACKGROUND

Cyclic dinucleotides (cyclic di-guanosine monophosphate (c-di-GMP) and cyclic di-adenosine monophosphate (c-di-AMP)) and lipopolysaccharides (LPS) are pathogen-associated molecular patterns (PAMPs). Individual impacts of PAMPs on immune system have been evaluated, but simultaneous actions of multiple PAMPs have not been studied.

OBJECTIVE

Examination the effects of cyclic dinucleotides and Porphyromonas gingivalis LPS on gingival epithelial cytokine response.

METHODS

Human gingival keratinocytes (HMK) were incubated with 1, 10, and 100 µM concentrations of c-di-GMP and c-di-AMP, either in the presence or absence of P. gingivalis LPS. Intra- and extracellular levels of interleukin (IL)-1β, IL-8, IL-1Ra, monocyte chemoattractant protein (MCP)-1, and vascular endothelial growth factor (VEGF), were measured using the Luminex technique.

RESULTS

LPS decreased extracellular IL-8 levels, while the presence of c-di-AMP inhibited this effect. Incubating HMK cells with c-di-AMP (alone or with LPS) elevated the extracellular level of MCP-1. Extracellular VEGF level increased when cells were incubated with LPS and c-di-GMP together, or with c-di-AMP alone. LPS and c-di-AMP suppressed intracellular IL-1β levels. The c-di-AMP elevated intracellular levels of IL-1Ra.

CONCLUSION

c-di-AMP and, to a lesser extent, c-di-GMP regulate keratinocyte cytokine response, either as an aggregator or as a suppressor of LPS, depending on the cytokine type.

The effect of lipopolysaccharide (LPS) on inflammatory markers in blood and brain and on behavior in individually-housed pigs

Most of us have experienced deterioration of mood while ill. In humans, immune activation is associated with lethargy and social withdrawal, irritability and aggression; changes in social motivation could, in theory, lead to less functional interactions. This might also be the case for animals housed in close confinement. Tail biting in pigs is an example of damaging social behavior, and sickness is thought to be a risk factor for tail biting outbreaks. One possible mechanism whereby sickness may influence behavior is through cytokines. To identify possible mediators between immune activation and behavioral change, we injected 16 gilts with lipopolysaccharide (LPS; O111:B4; 1.5 μg kg^-1 IV through a permanent catheter). In LPS-treated pigs, a significant increase in cortisol, TNF-α, IL-1 receptor antagonist, IL-6, and IL-8 was observed alongside decreased activity within the first 6 h after the injection. CRP was elevated at 12 and 24 h after injection, and food intake was reduced for the first 24 h after injection. Three days post-injection, LPS pigs had lower levels of noradrenaline in their hypothalamus, hippocampus and frontal cortex compared to saline-injected pigs. Pigs injected with LPS also had higher levels of the pro-inflammatory cytokine IFN-γ in their frontal cortex compared to saline-injected pigs. Thus, a low dose of LPS can induce changes in brain cytokine levels and neurotransmitter levels that persist after inflammatory and stress markers in the periphery have returned to baseline levels.

Terminalia bellirica (Gaertn.) Roxb fruit exerts anti-inflammatory effect via regulating arachidonic acid pathway and pro-inflammatory cytokines in lipopolysaccharide-induced RAW 264.7 macrophages

Terminalia bellirica (Gaertn.) Roxb. (Family: Combretaceae), known as Bhibhitaki in Sanskrit and locally known as Behera in India, has been used for centuries in Ayurveda, a universal system of medicine in India. The dried fruit of T. bellirica is used for the treatment of several disorders. The present study aims to explore the anti-inflammatory effects of aqueous acetone extracts isolated from T. bellirica (AATB) in RAW 264.7 cell lines. The AATB was prepared from the fruits of T. bellirica. Different concentrations of AATB (6.25-100 μg/ml) were used for MTT assay. The anti-inflammatory effect of AATB was evaluated by using different assays such as total cyclooxygenase (COX), 5-lipoxygenase (5-LOX) activity, nitrate and reactive oxygen species (ROS) production. The mRNA level expression of COX-2, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) were studied in LPS stimulated RAW 264.7 cells. AATB treatment significantly diminished the elevated levels of inflammatory markers. Moreover, AATB downregulated the mRNA level expression of TNF-α, IL-6 and COX-2 genes. The result of our study suggest the use of AATB and is able to reduce inflammatory conditions associated with various diseases.

Influence of Confounding Factors on Radiation Dose Estimation Using In Vivo Validated Transcriptional Biomarkers

For triage purposes following a nuclear accident, blood-based gene expression biomarkers can provide rapid dose estimates for a large number of individuals. Ionizing-radiation-responsive genes are regulated through the DNA damage-response pathway, which includes activation of multiple transcription factors. Modulators of this pathway could potentially affect the response of these biomarkers and consequently compromise accurate dose estimation calculations. In the present study, four potential confounding factors were selected: cancer condition, sex, simulated bacterial infection (lipopolysaccharide), and curcumin, an anti-inflammatory/antioxidant agent. Their potential influence on the transcriptional response to radiation of the genes CCNG1 and PHPT1, two biomarkers of radiation exposure ex vivo, was assessed. First, both CCNG1 and PHPT1 were detected in vivo in blood samples from radiotherapy patients and as such were validated as biomarkers of exposure. Importantly, their basal expression level was slightly but significantly affected in vivo by patients' cancer condition. Moreover, lipopolysaccharide stimulation of blood irradiated ex vivo led to a significant modification of CCNG1 and PHPT1 transcriptional response in a dose- and time-dependent manner with opposite regulatory effects. Curcumin also affected CCNG1 and PHPT1 transcriptional response counteracting some of the radiation induction. No differences were observed based on sex. Dose estimations calculated using linear regression were affected by lipopolysaccharide and curcumin. In conclusion, several confounding factors tested in this study can indeed modulate the transcriptional response of CCNG1 and PHPT1 and consequently can affect radiation exposure dose estimations but not to a level which should prevent the biomarkers' use for triage purposes.

Recognition of Lipopolysaccharide and Activation of NF-κB by Cytosolic Sensor NOD1 in Teleost Fish

Lipopolysaccharide (LPS) is the major component of the outer membrane of Gram-negative bacteria. This molecule can induce strong immune response and various biological effects. In mammals, TLR4 can recognize LPS and induce inflammatory response. However, the innate receptor in fish for recognizing LPS remains ambiguous. LPS can invade the cytoplasm via outer membrane vesicles produced by Gram-negative bacteria and could be detected by intracellular receptor caspase-11 in mammals, so, there may also exist the intracellular receptors that can recognize LPS in fish. NOD1 is a member of NOD-like receptors family and can recognize the iE-DAP in the cytoplasm in mammals. In fish, NOD1 can also respond to infection of Gram-negative bacteria and may play an important role in the identification of bacterial components. In this study, to study whether NOD1 is a recognition receptor for LPS, we detected the expression of NOD1 and several cytokines at transcript levels to determine whether LPS can induce inflammatory response in teleost fish and NOD1 can respond to LPS. Then, we perform the binding analysis between NOD1 and ultrapure LPS by using Streptavidin pulldown assay and enzyme-linked immunosorbent assay to prove that NOD1 can be combined with LPS, and using dual luciferase reporter gene assay to verify the signal pathways activated by NOD1. Next, through cell viability analysis, we proved that LPS-induced cytotoxicity can be mediated by NOD1 in fish. The results showed that NOD1 can identify LPS and activate the NF-κB signal pathway by recruiting RIPK2 and then promoting the expression of inflammatory cytokines to induce the resistance of organism against bacterial infection.

Dose matters: Direct killing or immunoregulatory effects of natural polysaccharides in cancer treatment

Polysaccharides from natural resources possess anti-tumor activities for decades, but the efficacy of polysaccharides as the adjuvant drugs for cancer treatment at prescribed doses remains open for debate. In this review, molecular mechanisms involved in direct killing effects of polysaccharides, including apoptosis, cell cycle arrest and mitochondria/DNA damage were described. However, the concentrations/doses used to reach the direct killing effects are too high to be applicable. Polysaccharides can also exert anti-tumor effects through immunoregulation at lower doses, and the effects of polysaccharides on natural killer cells, dendritic cells and other lymphocytes for tumor destruction, along with the receptor recognition and downstream signaling pathways, were delineated. Unfortunately, the prescribed doses of polysaccharides are too low to stimulate immunoresponse, resulting in the failure of some clinical trials. Therefore, understanding the sophisticated mechanisms of the immunoregulatory function of natural polysaccharides with refined doses for clinical use will help the standardization of traditional medicine.

Limulus amoebocyte lysate test via an open-microcavity optical biosensor

Almost since its discovery, Limulus amoebocyte lysate (LAL) testing has been an important part of the pharmaceutical quality control toolkit. It allows for in vitro endotoxin testing, which has replaced tests using animals, such as using rabbits' thermal response to judge pyrogenicity of test samples, thus leading to a less expensive and faster test of parenteral pharmaceuticals and medical devices that contact blood or cerebrospinal fluid. However, limited by the detection mechanisms of the LAL assays currently used in industry, further improvement in their performance is challenging. To address the growing demand on optimizing LAL assays for increased test sensitivity and reduced assay time, we have developed an LAL assay approach based on a detection mechanism that is different from those being used in industry, namely, gel-clot, turbidimetric, and chromogenic detection. Using a unique open-microcavity photonic-crystal biosensor to monitor the change in the refractive index due to the reaction between LAL regents and endotoxins, we have demonstrated that this approach has improved the LAL assay sensitivity by 200 times compared with the commercial standard methods, reduced the time needed for the assay by more than half, and eliminated the necessity to incubate the test samples. This study opens up the possibility of using the significantly improved LAL assays for a wide range of applications.

Anti-inflammatory effects of curcumin are associated with down regulating microRNA-155 in LPS-treated macrophages and mice

CONTEXT

The natural polyphenolic compound curcumin has been proved to modulate innate immune responses and possess anti-inflammatory properties. Nevertheless, the mechanism remains poorly understood, particularly regarding curcumin-regulated miRNAs under inflammatory response.

OBJECTIVE

This study investigates the role of miRNA-155 in the effects of curcumin on inflammatory response in cell and a mouse model.

MATERIALS AND METHODS

The anti-inflammatory activity of curcumin (5, 10 and 15 μM, 2 h) in lipopolysaccharide (LPS, 200 ng/mL)-induced cells were measured by quantitative PCR. The animals were treated orally by 20 mg/kg curcumin for 3 days before an LPS intraperitoneal injection (10 mg/kg, 16 h). MicroRNA (miRNA) expression and the underlying molecular mechanisms were assessed using transfection technique and western blotting.

RESULTS AND DISCUSSION

Curcumin efficiently inhibited LPS-induced cytokines (TNF-α, IL-6) and microRNA-155 (miR-155) expression (p < 0.05) without affecting the normally growth of Raw264.7 and THP-1 cells (IC₅₀ 21.8 and 22.3 μM at 48 h, respectively). Moreover, the levels of cytokines were suppressed by curcumin in miR-155 mimics transfected cells (p < 0.05). A blockade of PI3K/AKT signalling pathways resulted in a decreased level of miR-155 (p < 0.05). Curcumin effectively protected mice from sepsis as evidenced by decreasing histological damage, reducing AST (352.0 vs 279.3 U/L), BUN (14.8 vs 10.8 mmol/L) levels and the proportion of macrophages in spleen (31.1% vs 13.5%). MicroRNA-155 level and cytokines were also reduced in curcumin-treated mice (p < 0.05).

CONCLUSIONS

Curcumin's ability to suppress LPS-induced inflammatory response may be due to the inhibition of miR-155.

Inflammatory cytokine production in tumor cells upon chemotherapy drug exposure or upon selection for drug resistance

Tumor Necrosis Factor alpha (TNF-α) has been shown to be released by tumor cells in response to docetaxel, and lipopolysaccharides (LPS), the latter through activation of toll-like receptor 4 (TLR4). However, it is unclear whether the former involves TLR4 receptor activation through direct binding of the drug to TLR4 at the cell surface. The current study was intended to better understand drug-induced TNF-α production in tumor cells, whether from short-term drug exposure or in cells selected for drug resistance. ELISAs were employed to measure cytokine release from breast and ovarian tumor cells in response to several structurally distinct chemotherapy agents and/or TLR4 agonists or antagonists. Drug uptake and drug sensitivity studies were also performed. We observed that several drugs induced TNF-αrelease from multiple tumor cell lines. Docetaxel-induced cytokine production was distinct from that of LPS in both MyD88-positive (MCF-7) and MyD88-deficient (A2780) cells. The acquisition of docetaxel resistance was accompanied by increased constitutive production of TNF-αand CXCL1, which waned at higher levels of resistance. In docetaxel-resistant MCF-7 and A2780 cell lines, the production of TNF-α could not be significantly augmented by docetaxel without the inhibition of P-gp, a transporter protein that promotes drug efflux from tumor cells. Pretreatment of tumor cells with LPS sensitized MyD88-positive cells (but not MyD88-deficient) to docetaxel cytotoxicity in both drug-naive and drug-resistant cells. Our findings suggest that taxane-induced inflammatory cytokine production from tumor cells depends on the duration of exposure, requires cellular drug-accumulation, and is distinct from the LPS response seen in breast tumor cells. Also, stimulation of the LPS-induced pathway may be an attractive target for treatment of drug-resistant disease.

Time-dependent proteomic and genomic alterations in Toll-like receptor-4-activated human chondrocytes: increased expression of lamin A/C and annexins

Activation of Toll-like receptor-4 (TLR-4) in articular chondrocytes increases the catabolic compartment and leads to matrix degradation during the development of osteoarthritis. In this study, we determined the proteomic and genomic alterations in human chondrocytes during lipopolysaccharide (LPS)-induced inflammation to elucidate the underlying mechanisms and consequences of TLR-4 activation. Human chondrocytes were cultured with LPS for 12, 24, and 36 h to induce TLR-4 activation. The TLR-4-induced inflammatory response was confirmed by real-time PCR analysis of increased interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) expression levels. In TLR-4-activated chondrocytes, proteomic changes were determined by two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-mass spectroscopy analysis, and genomic changes were determined by microarray and gene ontology analyses. Proteomics analysis identified 26 proteins with significantly altered expression levels; these proteins were related to the cytoskeleton and oxidative stress responses. Gene ontology analysis indicated that LPS treatment altered specific functional pathways including ‘chemotaxis’, ‘hematopoietic organ development’, ‘positive regulation of cell proliferation’, and ‘regulation of cytokine biosynthetic process’. Nine of the 26 identified proteins displayed the same increased expression patterns in both proteomics and genomics analyses. Western blot analysis confirmed the LPS-induced increases in expression levels of lamin A/C and annexins 4/5/6. In conclusion, this study identified the time-dependent genomic, proteomic, and functional pathway alterations that occur in chondrocytes during LPS-induced TLR-4 activation. These results provide valuable new insights into the underlying mechanisms that control the development and progression of osteoarthritis.

Prim-O-glucosylcimifugin Attenuates Lipopolysaccharideinduced Inflammatory Response in RAW 264.7 Macrophages

BACKGROUND

Radix Saposhnikoviae (RS) exerts anti-inflammatory, analgesic, antipyretic, antioxidation effects and has been used in traditional Chinese medicine to treat common colds, headache, and rheumatoid arthritis. Prim-O-glucosylcimifugin (POG) is the highest content chromone and one of the major active constituents in RS.

OBJECTIVE

The study was aimed to explore the anti-inflammation effects of POG in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages.

MATERIALS AND METHODS

Cell viability was detected by Cell Counting Kit-8 assay. Production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6 was assessed by enzyme-linked immunosorbent assay. Real-time polymerase chain reaction and Western blot were performed to analyze mRNA and protein levels, respectively.

RESULTS

During the whole experiment, 15, 50, and 100 μg/mL of POG had no cytotoxicity on RAW 264.7 cells. POG dose-dependently inhibited the production of NO, TNF-α, IL-1β, and IL-6 that were induced by LPS. POG treatment downregulated the mRNA and protein expression inducible NO synthase (iNOS) and cyclooxygenase 2 (COX-2) in LPS-activated RAW 264.7 macrophages in a concentration-dependent manner. Furthermore, LPS-induced JAK2/STAT3 activation was prevented in RAW 264.7 macrophages by POG treatment. STAT3 overexpression significantly reversed the effects of POG on LPS-activated RAW 264.7 macrophages.

CONCLUSION

These results demonstrate that POG exerts anti-inflammatory effects through the inhibition of iNOS and COX-2 expression by inhibiting the phosphorylation of JAK2/STAT3.

SUMMARY

POG exerts anti-inflammatory effects in RAW 264.7 macrophages through the inhibition of iNOS and COX-2 expression by inhibiting JAK2/STAT3 signaling. Abbreviations used: LPS: Lipopolyssacharide; NO: Nitric oxide; TNF-α: Tumor necrosis factor-α; IL: Interleukin; RS: Radix Saposhnikoviae; POG: Prim-O-glucosylcimifugin; iNOS: Inducible NO synthase; COX2: Cyclooxygenase; FBS: Fetal bovine serum; DMSO: Dimethylsulfoxide; CCK-8: Cell Counting Kit; RIPA: Radio immunoprecipitation assay buffer; ECL: Enhanced chemiluminescence; SD: Standard deviation; ELISA: Enzyme-Linked immunosorbent assay.

Toll-Like Receptor 4 in Paraventricular Nucleus Mediates Visceral Hypersensitivity Induced by Maternal Separation

Neonatal maternal separation (MS) is a major early life stress that increases the risk of emotional disorders, visceral pain perception and other brain dysfunction. Elevation of toll-like receptor 4 (TLR4) signaling in the paraventricular nucleus (PVN) precipitates early life colorectal distension (CRD)-induced visceral hypersensitivity and pain in adulthood. The present study aimed to investigate the role of TLR4 signaling in the pathogenesis of postnatal MS-induced visceral hypersensitivity and pain during adulthood. The TLR4 gene was selectively knocked out in C57BL/10ScSn mice (Tlr4^-/-). MS was developed by housing the offspring alone for 6 h daily from postnatal day 2 to day 15. Visceral hypersensitivity and pain were assessed in adulthood. Tlr4^+/+, but not Tlr4^-/-, mice that had experienced neonatal MS showed chronic visceral hypersensitivity and pain. TLR4 immunoreactivity was observed predominately in microglia in the PVN, and MS was associated with an increase in the expression of protein and/or mRNA levels of TLR4, corticotropin-releasing factor (CRF), CRF receptor 1 (CRFR1), tumor necrosis factor-α, and interleukin-1β in Tlr4^+/+ mice. These alterations were not observed in Tlr4^-/- mice. Local administration of lipopolysaccharide, a TLR4 agonist, into the lateral cerebral ventricle elicited visceral hypersensitivity and TLR4 mRNA expression in the PVN, which could be prevented by NBI-35965, an antagonist to CRFR1. The present results indicate that neonatal MS induces a sensitization and upregulation of microglial TLR4 signaling activity, which facilitates the neighboring CRF neuronal activity and, eventually, precipitates visceral hypersensitivity in adulthood. Highlights (1)Neonatal MS does not induce chronic visceral hypersensitivity and pain in Tlr4^-/- mice.(2)Neonatal MS increases the expression of TLR4 mRNA, CRF protein and mRNA, CRFR1 protein, TNF-α protein, and IL-1β protein in Tlr4^+/+ mice.(3)TLR4 agonist LPS (i.c.v.) elicits visceral hypersensitivity and TLR4 mRNA expression in the PVN.

Chemical Structure of the Lipid A component of Pseudomonas sp. strain PAMC 28618 from Thawing Permafrost in Relation to Pathogenicity

Climate change causes permafrost thawing, and we are confronted with the unpredictable risk of newly discovered permafrost microbes that have disease-causing capabilities. Here, we first characterized the detailed chemical structure of the lipid A moiety from a Pseudomonas species that was isolated from thawing arctic permafrost using MALDI-based mass spectrometric approaches (i.e., MALDI-TOF MS and MALDI-QIT-TOF MSⁿ). The MALDI multi-stage mass spectrometry (MS) analysis of lipid A extracted from the Pseudomonas sp. strain PAMC 28618 demonstrated that the hexaacyl lipid A ([M−H]⁻ at m/z 1616.5) contains a glucosamine (GlcN) disaccharide backbone, two phosphates, four main acyl chains and two branched acyl chains. Moreover, the lipid A molecule–based structural activity relationship with other terrestrial Gram-negative bacteria indicated that strain PAMC 28618 has an identical lipid A structure with the mesophilic Pseudomonas cichorii which can cause rot disease in endive (Cichorium endivia) and that their bacterial toxicities were equivalent. Therefore, the overall lipid A validation process provides a general strategy for characterizing bacteria that have been isolated from arctic permafrost and analyzing their respective pathogenicities.

Lipopolysaccharide binds to and activates A1 adenosine receptors on human pulmonary artery endothelial cells

Previously, it was reported that A1 adenosine receptor antagonists prevent endotoxin-inducedacute lung injury and pulmonary arterial endothelial cell damage. In competition radioligand binding experiments in membranes prepared from human pulmonary artery endothelial cells (PAECs), lipopolysaccharides (LPSs) of Escherichia coli, Salmonella typhimurium, Klebsiella pneumoniae, and Pseudomonas aeruginosa displaced the binding of a selective A adenosine receptor antagonist [125I]-BWA844U (IC 50 values: 195 ng/ml, 290 ng/ml, 602 ng/ml, and 6931 ng/ml, respectively)in a dose-dependent, competitive manner. There was no displacement of this radioligand by enterotoxin (≤ 10 μg/ml), diphosphoryl lipid A (≤ 10μg/ml), and glycolipids, monosialoganglioside(≤ 1μg/ml), lactocerebroside (≤ 100μg/ml), or NBD galactocerebroside (≤ 100 μg/ml). Based on calculated IC values, LPS ( E. coli, IC50 111 ng/ml) 50 6 displaced the selective A1 adenosine receptor agonist, [3H]-2-chloro, N -cyclopentyladenosine (CCPA) in human PAECs with a potency profile, CCPA > LPS > 2-phenylaminoadenosine (CV 1808), a selective A2 adenosine receptor agonist. The potency profile for displacement of the selective A μ 2a adenosine receptor agonist [ 3H]-CGS 21680 was CV 1808 > CCPA. LPS ( E. coli 0.1 pg/ml—10 g/ml) did not displace [3H]-CGS 21680 binding. In human PAECs, IL-6 and TXA2 release induced by LPS (0—1 μg/ml) or CCPA (0—1 μM) at high doses was significantly reduced by the selective A1 adenosine receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine(DPCPX; 1 μM). These data suggest that LPS binds to and activates A1 adenosine receptors on human PAECs to induce the release of IL-6 and TXA 2. Activation of A1 adenosine receptors on human PAECs by LPS, may contribute to the pathophysiology of acute lung injury associated with Gram-negative septicemia and endotoxemia.

LPS binding protein does not participate in the pharmacokinetics of E5564

E5564, a lipid A analogue, is a potent antagonist of lipopolysaccharide (LPS). Clinically, E5564 was developed as a possible therapy for treatment of sepsis and septic shock. Surface plasmon resonance (SPR) analysis indicates that E5564 binds to LPS binding protein (LBP), in a manner similar to LPS. Gel-filtration radioactive chromatograms of [14C]-E5564 in plasma revealed that E5564 initially distributes to the lipoprotein fractions, separated from high-density lipoprotein (HDL); the bound fraction is then released and binds to HDL. Similar results were obtained by heparin-manganese precipitation. At doses of E5564 relevant to its clinical use ( i.e. 6 µg/ml), antibodies against LBP did not influence either the distribution of E5564 to non-HDL lipoprotein fractions or the transfer of E5564 from non-HDLs to HDL. Under these conditions, transfer of E5564 to HDL occurs similarly in the plasma of LBP knockout (KO) mice as in the plasma from wild-type mice. In addition, plasma clearance of E5564 in LBP KO mice is similar to that of wild-type mice. Thus, LBP binds E5564 in a manner similar to LPS, but does not play a role in E5564 redistribution/binding to lipoprotein and plasma clearance.

Protein-bound polysaccharides from Coriolus versicolor attenuate LPS-induced synthesis of pro-inflammatory cytokines and stimulate PBMCs proliferation

Protein-bound polysaccharides (PBP) isolated from Coriolus versicolor (CV) are classified as biological response modifiers capable of exhibiting various biological activities, such as anti-tumour and immunopotentiating activity. Since we have found in vivo studies that the tested PBP induced prolongation of endotoxin fever in rats, the aim of the present study was to investigate the in vitro effect of the PBP on the production of pro-inflammatory cytokines by the lipolysaccharide (LPS)-stimulated rat peripheral blood mononuclear cells (PBMCs). The results showed that the PBP affect the immunomodulating properties of the LPS-treated PBMCs by the enhancement of mitogenic activity and attenuation of the LPS-induced production of interleukin (IL)-1β and IL-6. Moreover, the tested polysaccharides peptides themselves also exhibit immunomodulatory properties manifested in the increased cell proliferation and pro-inflammatory cytokine release from PBMCs. The effect of PBP on the both phenomena was time-dependent and occurred in the U-shaped dose response manner. These findings are significant when considering the use of commercially available PBP from CV extract by cancer patients suffering from immunodeficiency, who may experience microbial infections during therapy.

Computational Approaches to Toll-Like Receptor 4 Modulation

Toll-like receptor 4 (TLR4), along with its accessory protein myeloid differentiation factor 2 (MD-2), builds a heterodimeric complex that specifically recognizes lipopolysaccharides (LPS), which are present on the cell wall of Gram-negative bacteria, activating the innate immune response. Some TLR4 modulators are undergoing preclinical and clinical evaluation for the treatment of sepsis, inflammatory diseases, cancer and rheumatoid arthritis. Since the relatively recent elucidation of the X-ray crystallographic structure of the extracellular domain of TLR4, research around this fascinating receptor has risen to a new level, and thus, new perspectives have been opened. In particular, diverse computational techniques have been applied to decipher some of the basis at the atomic level regarding the mechanism of functioning and the ligand recognition processes involving the TLR4/MD-2 system at the atomic level. This review summarizes the reported molecular modeling and computational studies that have recently provided insights into the mechanism regulating the activation/inactivation of the TLR4/MD-2 system receptor and the key interactions modulating the molecular recognition process by agonist and antagonist ligands. These studies have contributed to the design and the discovery of novel small molecules with promising activity as TLR4 modulators.

The Isothiocyanate Isolated from Moringa oleifera Shows Potent Anti-Inflammatory Activity in the Treatment of Murine Subacute Parkinson's Disease

The present study was aimed at estimating a possible neuroprotective effect of glucomoringin (GMG) [4-(α-L-rhamnopyranosyloxy)benzyl glucosinolate] bioactivated with the enzyme myrosinase to form the corresponding isothiocyanate [4-(α-L-rhamnopyranosyloxy)benzyl C; moringin] in the treatment or prevention of Parkinson's disease (PD). In this study, the beneficial effects of moringin were compared with those of pure GMG, not enzymatically activated, in an in vivo experimental mouse model of subacute PD. Subacute PD was induced in C57BL/6 mice by administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Mice were pretreated daily for 1 week with moringin (10 mg/kg +5 μL myrosinase/mouse) and with GMG (10 mg/kg). Behavioral evaluations were also performed to assess motor deficits and bradykinesia in MPTP mice. Besides, assuming that pretreatment with moringin could modulate the triggering of inflammatory cascade with a correlated response, we tested its in vitro anti-inflammatory activity by using a model of RAW 264.7 macrophages stimulated with lipopolysaccharide. Achieved results in vivo showed a higher efficacy of moringin compared with GMG not only to modulate the inflammatory pathway but also oxidative stress and apoptotic pathways. In addition, the greater effectiveness of moringin in countering mainly the inflammatory pathway has been corroborated by the results obtained in vitro. The relevance and innovation of the present study lie in the possible use of a safe formulation of a bioactive compound, resulting from exogenous myrosinase hydrolysis of the natural phytochemical GMG, which can be used in clinical practice as a useful drug for the treatment or prevention of PD.

The Role of Nuclear Factor-E2-Related Factor 1 in the Oxidative Stress Response in MC3T3-E1 Osteoblastic Cells

BACKGROUND

Reactive oxygen species (ROS) and antioxidants are associated with maintenance of cellular function and metabolism. Nuclear factor-E2-related factor 1 (NFE2L1, Nrf1) is known to regulate the expression of a number of genes involved in oxidative stress and inflammation. The purpose of this study was to examine the effects of NFE2L1 on the response to oxidative stress in osteoblastic MC3T3-E1 cells.

METHODS

The murine calvaria-derived MC3T3-E1 cell line was exposed to lipopolysaccharide (LPS) for oxidative stress induction. NFE2L1 effects were evaluated using small interfering RNA (siRNA) for NFE2L1 mRNA. ROS generation and the levels of known antioxidant enzyme genes were assayed.

RESULTS

NFE2L1 expression was significantly increased 2.4-fold compared to the control group at 10 μg/mL LPS in MC3T3-E1 cells (P<0.05). LPS increased formation of intracellular ROS in MC3T3-E1 cells. NFE2L1 knockdown led to an additional increase of ROS (20%) in the group transfected with NFE2L1 siRNA compared with the control group under LPS stimulation (P<0.05). RNA interference of NFE2L1 suppressed the expression of antioxidant genes including metallothionein 2, glutamatecysteine ligase catalytic subunit, and glutathione peroxidase 1 in LPS-treated MC3T3-E1 cells.

CONCLUSION

Our results suggest that NFE2L1 may have a distinct role in the regulation of antioxidant enzymes under inflammation-induced oxidative stress in MC3T3-E1 osteoblastic cells.

Endothelial-to-mesenchymal transition in lipopolysaccharide-induced acute lung injury drives a progenitor cell-like phenotype

Pulmonary vascular endothelial function may be impaired by oxidative stress in endotoxemia-derived acute lung injury. Growing evidence suggests that endothelial-to-mesenchymal transition (EndMT) could play a pivotal role in various respiratory diseases; however, it remains unclear whether EndMT participates in the injury/repair process of septic acute lung injury. Here, we analyzed lipopolysaccharide (LPS)-treated mice whose total number of pulmonary vascular endothelial cells (PVECs) transiently decreased after production of reactive oxygen species (ROS), while the population of EndMT-PVECs significantly increased. NAD(P)H oxidase inhibition suppressed EndMT of PVECs. Most EndMT-PVECs derived from tissue-resident cells, not from bone marrow, as assessed by mice with chimeric bone marrow. Bromodeoxyuridine-incorporation assays revealed higher proliferation of capillary EndMT-PVECs. In addition, EndMT-PVECs strongly expressed c-kit and CD133. LPS loading to human lung microvascular endothelial cells (HMVEC-Ls) induced reversible EndMT, as evidenced by phenotypic recovery observed after removal of LPS. LPS-induced EndMT-HMVEC-Ls had increased vasculogenic ability, aldehyde dehydrogenase activity, and expression of drug resistance genes, which are also fundamental properties of progenitor cells. Taken together, our results demonstrate that LPS induces EndMT of tissue-resident PVECs during the early phase of acute lung injury, partly mediated by ROS, contributing to increased proliferation of PVECs.

Identification, characterization and expression analysis of ERK2 in Chinese mitten crab Eriocheir sinensis after challenge with LPS and Aeromonas hydrophila

Farming of Eriocheir sinensis was seriously threaten by the infection of opportunistic pathogens, especially the gram-negative bacterium. In this paper, we analyzed the sequence of extracellular signal-regulated kinases 2 (ERK2) of E. sinensis (EsERK2) and its expression levels after challenge with LPS and Aeromonas hydrophila in both in vivo and in vitro examination. The full-length cDNA sequence of EsERK2 was 2455 bp in size with an open reading frame (ORF) of 1095 bp, encoding the protein of 365 amino acids. It owned a predicted molecular mass of 42.4 kDa and a theoretical isoelectric point (pI) of 5.93. EsERK2 was distributed in all examined tissues including haemocyte, gonad, hepatopancreas, gill, muscle heart, stomach and intestine, but its expression level was significantly higher in hepatopancreas than it in other examined tissues. The expression level of EsERK2 increased significantly after LPS challenge at 2 h (P < 0.05), and then gradually increased and reached highest at 16 h. However, its expression level decreased significantly after A. hydrophila challenge at 4 h, and then gradually decreased till 24 h (P < 0.05), and returned to its initial value at 36 h. According to the immunofluorescence assay and western blotting assay, EsERK2 was found to be distributed mainly in cytoplasm of haemocyte, and its expression level showed a prominent boost in primary cultured haemocytes after challenge with LPS and A. hydrophila in vitro. These results indicated that the expression of EsERK2 was sensitive to the exterior stimulants and its encoding protein might be associated with the signaling transduction in response to exterior pathogens in E. sinensis.