Response of man to endotoxin

Fucoidan from Durvillaea Antarctica enhances the anti-cancer effect of anti-PD-L1 antibody by activating dendritic cells and T cells

Immune checkpoint inhibitors are showing groundbreaking results in tumor immunotherapy. However, there are cases where treatment efficiency is insufficient due to limitations in immune activity, and various trials to overcome this are being studied. In this study, we investigated the immune activation ability of fucoidan extracted from Durvillaea antarctica (FDA) and whether it can enhance the anti-cancer effects of immune checkpoint inhibitors. FDA treatment resulted in an elevation of co-stimulator and major histocompatibility complex molecule expression, as well as the production of pro-inflammatory cytokines in bone marrow-derived and splenic dendritic cells (DCs). Administration of 50 mg/kg FDA increased the number of splenic CD8 T cells by >1.4-fold compared to PBS administration. Additionally, 50 mg/kg FDA increased the production of IFN-γ in CD4 and CD8 T cells by 4.3-fold and 7.2-fold, respectively, compared to the PBS control. FDA promoted immune cell activation was TLR4 dependent. Furthermore, anti-PD-L1 antibody administration inhibited CT-26 tumor growth by approximately 3-fold compared to the PBS control group, whereas combined treatment with FDA and anti-PD-L1 antibody showed an 8.4-fold tumor growth inhibition effect compared to the PBS control group. Therefore, FDA may be used to enhance the anti-cancer effects of immune checkpoint inhibitors.

Ethnopharmacological study on Adenosma buchneroides Bonati inhibiting inflammation via the regulation of TLR4/MyD88/NF-κB signaling pathway

Adenosma buchneroides Bonati, also known as fleagrass, is an important medicinal plant used by the Akha (Hani) people of China for treating inflammation-related skin swelling, acne, and diarrhoea, among other conditions. In this study, we aimed to evaluate the anti-inflammatory activities and explore the molecular mechanisms of fleagrass on treating skin swelling and acne. The results demonstrated that fleagrass inhibited the enzymatic activities of 5-LOX and COX-2 in vitro, and decreased the release of NO, IL-6, TNF-α, and IL-10 in the LPS-induced RAW264.7 macrophages. The levels of proteins associated with the nuclear factor-kappa B (NF-κB) pathway were examined by western blotting and immunofluorescence, demonstrating that fleagrass downregulated the expression of TLR4, MyD88, NF-κB/p65, and iNOS and blocked the nuclear translocation of NF-κB/p65. Furthermore, fleagrass exhibited acute anti-inflammatory activity in paw oedema models. The results confirm that fleagrass exhibits remarkable anti-inflammatory activity and can be used in alleviating inflammation, suggesting that fleagrass has the potential to be a novel anti-inflammatory agent.

Analysis of commercially available snake antivenoms reveals high contents of endotoxins in some products

As injectable therapeutics, snake antivenoms must meet specifications for endotoxin content. The Limulus amebocyte lysate (LAL) test was used to evaluate the endotoxin content in several commercially available antivenoms released for clinical use. It was found that some products have endotoxin concentrations higher than the accepted limit for these contaminants. These results emphasize the need to include endotoxin determination as part of the routine evaluation of antivenoms by manufacturers and regulatory agencies.

Guggulsterone protects against lipopolysaccharide-induced inflammation and lethal endotoxemia via heme oxygenase-1

Guggulsterone (GS) is a phytosterol used to treat inflammatory diseases. Although many studies have examined the anti-inflammatory activities of GS, the detailed mechanisms of GS in lipopolysaccharide (LPS)-induced inflammation and endotoxemia have not yet been examined. Therefore, we investigated the anti-inflammatory effects of GS on LPS-induced inflammation. In murine peritoneal macrophages, the anti-inflammatory activity of GS was primarily mediated by heme oxygenase-1 (HO-1) induction. HO-1 induction by GS was mediated by GSH depletion and reactive oxygen species (ROS) production. The ROS generated by GS caused the phosphorylation of GSK3β (ser9/21) and p38, leading to the translocation of nuclear factor erythroid-related factor 2 (Nrf2), which ultimately induced HO-1. In addition, GS pretreatment significantly inhibited inducible nitric oxide synthase (iNOS), iNOS-derived NO, and COX-2 protein and mRNA expression, and production of COX-derived prostaglandin PGE2, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α). In a mouse model of endotoxemia, GS treatment prolonged survival and inhibited the expression of inflammatory mediators, including IL-1β, IL-6, and TNF-α. GS treatment also inhibited LPS-induced liver injury. These results suggest that GS-induced HO-1 could exert anti-inflammatory effects via ROS-dependent GSK (ser21/9)-p38 phosphorylation and nuclear translocation of Nrf2.

IRAK3 Knockout and Wildtype THP-1 Monocytes as Models for Endotoxin Detection Assays and Fusobacterium nucleatum Bacteriophage FNU1 Cytokine Induction

Microbial resistance to antibiotics poses a tremendous challenge. Bacteriophages may provide a useful alternative or adjunct to traditional antibiotics. To be used in therapy, bacteriophages need to be purified from endotoxins and tested for their effects on human immune cells. Interleukin-1 Receptor Associated Kinase-3 (IRAK3) is a negative regulator of inflammation and may play a role in the modulation of immune signalling upon bacteriophage exposure to immune cells. This study aimed to investigate the immune effects of crude and purified bacteriophage FNU1, a bacteriophage that targets the oral pathobiont Fusobacterium nucleatum, on wildtype and IRAK3 knockout THP-1 monocytic cell lines. The IRAK3 knockout cell line was also used to develop a novel endotoxin detection assay. Exposure to crude FNU1 increased the production of pro-inflammatory cytokines (Tumour necrosis factor - alpha (TNF-α) and Interleukin 6 (IL-6)) compared to purified FNU1 in wildtype and IRAK3 knockout THP-1 monocytes. In the IRAK3 knockout THP-1 cells, exposure to crude FNU1 induced a higher immune response than the wildtype monocytes, supporting the suggestion that the inhibitory protein IRAK3 regulates reactions to endotoxins and impurities in bacteriophage preparations. Finally, the novel endotoxin detection assay generated here provides a robust and accurate method for determining endotoxin concentrations.

Common Variable Immunodeficiency Patient Fecal Microbiota Transplant Recapitulates Gut Dysbiosis

Purpose

Patients with non-infectious complications have worse clinical outcomes in common variable immunodeficiency (CVID) than those with infections-only. Non-infectious complications are associated with gut microbiome aberrations, but there are no reductionist animal models that emulate CVID. Our aim in this study was to uncover potential microbiome roles in the development of non-infectious complications in CVID.

Methods

We examined fecal whole genome shotgun sequencing from patients CVID, and non-infectious complications, infections-only, and their household controls. We also performed Fecal Microbiota transplant from CVID patients to Germ-Free Mice.

Results

We found potentially pathogenic microbes Streptococcus parasanguinis and Erysipelatoclostridium ramosum were enriched in gut microbiomes of CVID patients with non-infectious complications. In contrast, Fusicatenibacter saccharivorans and Anaerostipes hadrus, known to suppress inflammation and promote healthy metabolism, were enriched in gut microbiomes of infections-only CVID patients. Fecal microbiota transplant from non-infectious complications, infections-only, and their household controls into germ-free mice revealed gut dysbiosis patterns in recipients from CVID patients with non-infectious complications, but not infections-only CVID, or household controls recipients.

Conclusion

Our findings provide a proof of concept that fecal microbiota transplant from CVID patients with non-infectious complications to Germ-Free mice recapitulates microbiome alterations observed in the donors.

Inflammation protein quantification by multiple reaction monitoring mass spectrometry in lipopolysaccharide-stimulated THP-1 cells

RATIONALE

Inflammation is a cascade of events mediated by a cytokine network triggering the cellular response. In order to monitor the modulation of the crucial inflammatory proteins, e.g., Tumour Necrosis Factor-α (TNF-α), Interferon-γ (INF-γ), Interleukin-8 (IL-8) and Interleukin-10 (IL-10), upon stimulation with endotoxins, differentiated and undifferentiated THP-1 cells were treated with lipopolysaccharides (LPSs) from E. coli, key cell wall components of Gram-negative bacteria.

METHODS

The multiple reaction monitoring mass spectrometry (MRM-MS) method was optimized by using the standard proteins to be quantified, in order to construct external calibration curves and define the analytical parameters. The developed method was used to quantify the above-mentioned inflammatory proteins in THP-1 differentiated cells upon stimulation with LPSs with high accuracy, sensitivity, and robustness.

RESULTS

The analysis of such proteins in MRM mode allowed the kinetics of stimulation along the time up to 24 h to be followed and the MS results were found to be comparable with those obtained by Western-blotting. A significant increase in TNF-α release triggered a cascade mechanism leading to the production of INF-γ and IL-8. IL-10, instead, was found to be constant throughout the process.

CONCLUSIONS

The developed MRM-MS method allowed the quantification of TNF-α, INF-γ, IL-8 and IL-10 along a time-course from 2 to 24 h. Hence, a trace of the kinetics of the inflammatory response in THP-1 cells upon stimulation with E. coli LPSs was obtained. Finally, the extensibility of the developed MRM method to serum samples and other matrices demonstrated the versatility of the approach and the possibility to quantify multiple target proteins in different biological samples by using a few microliters in a single analysis.

Automated blood sampling in canine telemetry model: Enhanced assessment of immune liabilities

INTRODUCTION

This manuscript presents a successful integration of multi-timepoint biomarker blood sampling (e.g., cytokines) in a conscious dog cardiovascular study using automated blood sampling via vascular access ports in telemetry instrumented dogs. In addition to determining plasma exposure of the test compound, the assessment of biomarkers of interest allows for more comprehensive preclinical evaluation on a traditional conscious dog cardiovascular (CV) telemetry study especially for immunology and immune-oncology molecules. This model system provides a rapid and efficient means to quickly gain understanding of potential effects on key cardiovascular parameters in large species that are commonly used for preclinical safety evaluations while collecting multiple blood samples for drug and cytokine analysis.

METHODS

Male beagle dogs were chronically implanted with telemetry devices (PhysioTel™ model D70-PCTP) and vascular access ports (SPMID-GRIDAC-5NC). BASi Culex-L automated blood sampling (ABS) (Bioanalytical Systems, Inc) system was used to collect blood samples at multiple time points for cytokine analysis. Four beagles received low-dose lipopolysaccharide solution (LPS) (0.1 and 0.5 μg/mL). The following cytokines were measured by Milliplex® map Canine Cytokine Magnetic Bead Panel: Interleukin (IL) 2, IL-6, IL-7, IL-8, IL-10, IL-15, IL-18, TNF-α, MCP-1, KC-like, GM-CSF, IFN gamma, and IP10.

RESULTS

Low dose LPS administration induced a pronounced dose-dependent, transient release of key inflammatory cytokines (IL-2, IL-6, IL-10, TNF-α, MCP-1, and KC-like). Cytokine responses were similar to other canine and human endotoxin models. LPS administration led to an increase in body temperature, heart rate, and mean arterial pressure, as well as a decrease in QTcV interval.

CONCLUSION

Successful incorporation of cytokine analysis in telemetry instrumented dogs with vascular access ports allows for translational PK/PD modeling of both efficacy and safety of compounds in the immunology as well as the immune-oncology therapeutic areas designed to modulate the immune system. Remote collection of blood samples simultaneously with CV endpoints is a significant enhancement for assessment of biomarkers that are sensitive to animal handling and excitement associated with room disturbances which are obligatory with manual blood collection. Furthermore, implementing this approach has also refined our animal welfare procedure by reducing the handling during a study and thereby reducing stress (positive refinement 3R impact).

Insights into the modulatory role of cyclosporine A and its research advances in acute inflammation

Cyclosporine A(CsA), a classic immunosuppressant, is mainly applied for solid organ transplantation and some autoimmune diseases by suppressing T lymphocytes. Early studies showed that the application of CsA is primarily focused on chronic but not acute inflammation, nevertheless, increasing evidence supporting a role for CsA in acute inflammation, although most of proofs come from experimental models. It has long been known to us that the nuclear factor of activated T cells (NFAT) is the target of CsA to regulate T lymphocytes. However, NFAT also contributes to the regulation of innate immune cells, thus, CsA can not only target lymphocytes but also innate immune cells such as monocytes/macrophages, dendritic cells and neutrophils, which provides a basis for CsA to act on acute inflammation. Moreover, some other pathophysiological events in acute inflammation such as decreased vascular activity, mitochondrial dysfunction and endogenous cell apoptosis can also be alleviated by CsA. There being a moderate successes in the application of CsA for experimental acute inflammation such as sepsis, trauma/hemorrhagic shock and ischemic/reperfusion injury, yet data of the clinical treatment is not clear. In this review, we will critically analyze the existing hypotheses, summarize the application of CsA and its possible mechanisms in various acute inflammation over the past few decades, hope to provide some clues for the clinical treatment of acute inflammation.

Live attenuated Salmonella Typhimurium with monophosphoryl lipid A retains ability to induce T-cell and humoral immune responses against heterologous polysaccharide of Shigella flexneri 2a

Shigella flexneri 2a (Sf2a) is one of the most frequently isolated Shigella strains that causes the endemic shigellosis in developing countries. In this study, we used recombinant attenuated Salmonella vaccine (RASV) strains to deliver Sf2a O-antigen and characterized the immune responses induced by the vectored O-antigen. First, we identified genes sufficient for biosynthesis of Sf2a O-antigen. A plasmid containing the identified genes was then introduced into the RASV strains, which were manipulated to produce only the heterologous O-antigen and modified lipid A. After oral immunization of mice, we demonstrated that RASV strains could induce potent humoral immune responses as well as robust CD4⁺ T-cell responses against Sf2a Lipopolysaccharide (LPS) and protect mice against virulent Sf2a challenge. The induced serum antibodies mediated high levels of Shigella-specific serum bactericidal activity and C3 deposition. Moreover, the IgG⁺ B220^low/int B_M cell and T follicular helper (Tfh) cell responses could also be triggered effectively. The live attenuated Salmonella with the modified lipid A delivering Sf2a O-antigen polysaccharide showed the same ability to induce immune responses against Sf2a LPS as the strain with the original lipid A. These findings underscore the potential of RASV delivered Sf2a O-antigen for induction of robust CD4⁺ T-cell and IgG responses and warrant further studies toward the development of Shigella vaccine candidates with RASV strains.

Lipopolysaccharide and Morphine-3-Glucuronide-Induced Immune Signalling Increases the Expression of Polysialic Acid in PC12 Cells

Polysialic acid (polySia), a long homopolymer of 2,8-linked sialic acids, is abundant in the embryonic brain and is restricted largely in adult brain to regions that exhibit neurogenesis and structural plasticity. In the central nervous system (CNS), polySia is highly important for cell-cell interactions, differentiation, migration and cytokine responses, which are critical neuronal functions regulating intercellular interactions that underlie immune signalling in the CNS. In recent reports, a metabolite of morphine, morphine-3-glucuronide (M3G), has been shown to cause immune signalling in the CNS. In this study, we compared the effects of neurite growth factor (NGF), lipopolysaccharide (LPS) and M3G exposure on the expression of polySia in PC12 cells using immunocytochemistry and Western blot analysis. PolySia was also extracted from stimulated cell proteins by endo-neuraminidase digestion and quantitated using fluorescent labelling followed by HPLC analysis. PolySia expression was significantly increased following NGF, M3G or LPS stimulation when compared with unstimulated cells or cells exposed to the TLR4 antagonist LPS-RS. Additionally, we analyzed the effects of test agent exposure on cell migration and the oxidative stress response of these cells in the presence and absence of polySia expression on their cell surface. We observed an increase in oxidative stress in cells without polySia as well as following M3G or LPS stimulation. Our study provides evidence that polySia expression in neuronal-like PC12 cells is influenced by M3G and LPS exposure alike, suggestive of a role of TLR4 in triggering these events.

Pathological Mechanisms Underlying Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

The underlying molecular basis of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is not well understood. Characterized by chronic, unexplained fatigue, a disabling payback following exertion ("post-exertional malaise"), and variably presenting multi-system symptoms, ME/CFS is a complex disease, which demands a concerted biomedical investigation from disparate fields of expertise. ME/CFS research and patient treatment have been challenged by the lack of diagnostic biomarkers and finding these is a prominent direction of current work. Despite these challenges, modern research demonstrates a tangible biomedical basis for the disorder across many body systems. This evidence is mostly comprised of disturbances to immunological and inflammatory pathways, autonomic and neurological dysfunction, abnormalities in muscle and mitochondrial function, shifts in metabolism, and gut physiology or gut microbiota disturbances. It is possible that these threads are together entangled as parts of an underlying molecular pathology reflecting a far-reaching homeostatic shift. Due to the variability of non-overlapping symptom presentation or precipitating events, such as infection or other bodily stresses, the initiation of body-wide pathological cascades with similar outcomes stemming from different causes may be implicated in the condition. Patient stratification to account for this heterogeneity is therefore one important consideration during exploration of potential diagnostic developments.

Occurrence of bacteria and endotoxins in fermented foods and beverages from Nigeria and South Africa

In Africa, fermented foods and beverages play significant roles in contributing to food security. Endotoxins are ubiquitous heat stable lipopolysaccharide (LPS) complexes situated in the outer cell membranes of Gram-negative bacteria. This study evaluated the microbiological quality of fermented foods (ogiri, ugba, iru, ogi and ogi baba) and beverages (mahewu and umqombothi) from selected Nigerian and South African markets. The bacterial diversity of the fermented foods was also investigated and the identity of the isolates confirmed by biochemical and molecular methods. Isolate grouping was established through hierarchal clustering and the samples were further investigated for endotoxin production with the chromogenic Limulus Amoebocyte Lysate assay. The total aerobic count of the samples ranged from 5.7 to 10.8 Log CFU/g. Fourteen bacteria genera were detected with most of the isolates being members of the Enterobacteriaceae family. Sphingomonas paucimobilis and Escherichia coli were the dominant Gram-negative bacterial species detected. There were considerable variations in the concentrations of endotoxins produced and the lowest endotoxin concentration was found in ogi (4.3 × 10 EU/g) and the highest in iru (5.5 × 10⁴ EU/g) while, 44% of umqombothi samples had endotoxins. Ogi baba samples had better microbial quality than other samples due to its reduced bacterial load and endotoxin levels. There was a strong positive (r = 0.714, r = 0.996) and significant (p < 0.01) correlation between the endotoxin levels and bacterial loads of the samples. Some previously unreported species of bacteria found in the fermented foods included Aeromonas haemolyticus and Rhizobium radiobacter. This is the first comprehensive report on endotoxins in fermented foods and beverages in Africa. Furthermore, the occurrence of pathogenic bacteria and toxins in the foods and beverages is of serious concern that calls for immediate action.

Development of boronic acid-functionalized mesoporous silica-coated core/shell magnetic microspheres with large pores for endotoxin removal

Endotoxins are found almost everywhere and possess high toxicity in vivo and in vitro. Here we design a novel boronate affinity material, called boronic acid-functionalized mesoporous silica-coated core/shell magnetic microspheres (Fe₃O₄@nSiO₂@mSiO₂-BA) with large pores (pore size > 20 nm) based on the chemical structure and physical properties of endotoxins, for facile and highly efficient removal of endotoxins. Dual modes for endotoxin removal were proposed and confirmed in this work: the endotoxin aggregates with size < 20 nm were bound with boronic acid ligands chemically modified on the inner and outer surface of the large pores of Fe₃O₄@nSiO₂@mSiO₂-BA microspheres; while the larger endotoxin micelles (size >20 nm) were absorbed on the outer surface of the prepared material based on boronate affinity. Transmission electron microscopy (TEM), X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms and Fourier transform infrared (FT-IR) spectroscopy confirm that Fe₃O₄@nSiO₂@mSiO₂-BA microspheres possess core/shell structure, uniform diameter (520 nm), high surface area (205.57 m²/g), large mesopores (21.8 nm) and boronic acid ligands. The purification procedures of Fe₃O₄@nSiO₂@mSiO₂-BA microspheres for endotoxin were optimized, and 50 mM NH₄HCO₃ (pH 8.0) and 0.05 M fructose were selected as loading/washing, elution buffers, respectively. The binding capacity of Fe₃O₄@nSiO₂@mSiO₂-BA microspheres for endotoxin was calculated to be 60.84 EU/g under the optimized conditions. Finally, the established analytical method was applied to remove endotoxins from plasmid DNA. After endotoxin removal, the endotoxin content in plasmid DNA was reduced from 0.0026 to 0.0006 EU/mL for two-fold concentration, and from 0.0088 to 0.0022 EU/mL for five-fold concentration after binding, respectively. Additional advantages of the prepared boronate affinity material include excellent stability, reusability/repeatability, and low cost. Boronate affinity materials with large pores could thus prove to be powerful adsorbents for endotoxin removal and the potential applications in the aspects of biological research, pharmaceutical industry, and life health.

Inflammation and Disease: Modelling and Modulation of the Inflammatory Response to Alleviate Critical Illness

Critical illness, a constellation of interrelated inflammatory and physiological derangements occurring subsequent to severe infection or injury, affects a large number of individuals in both developed and developing countries. The prototypical complex system embodied in critical illness has largely defied therapy beyond supportive care. We have focused on the utility of data-driven and mechanistic computational modelling to help address the complexity of critical illness and provide pathways towards discovering potential therapeutic options and combinations. Herein, we review recent progress in this field, with a focus on both animal and computational models of critical illness. We suggest that therapy for critical illness can be posed as a model-based dynamic control problem, and discuss novel theoretical and experimental approaches involving biohybrid devices aimed at reprogramming inflammation dynamically. Together, these advances offer the potential for Model-based Precision Medicine for critical illness.

Tissue-Specific Differential Expression of Novel Genes and Long Intergenic Noncoding RNAs in Humans With Extreme Response to Evoked Endotoxemia

BACKGROUND

Cytokine responses to activation of innate immunity differ between individuals, yet the genomic and tissue-specific transcriptomic determinants of inflammatory responsiveness are not well understood. We hypothesized that tissue-specific mRNA and long intergenic noncoding RNA (lincRNA) induction differs between individuals with divergent evoked inflammatory responses.

METHODS

In the GENE Study (Genetics of Evoked Response to Niacin and Endotoxemia), we performed an inpatient endotoxin challenge (1 ng/kg lipopolysaccharide [LPS]) in healthy humans. We selected individuals in the top (high responders) and bottom (low responders) extremes of inflammatory responses and applied RNA sequencing to CD14 monocytes (N=15) and adipose tissue (N=25) before and after LPS administration.

RESULTS

Although only a small number of genes were differentially expressed at baseline, there were clear differences in the magnitude of the transcriptional response post-LPS between high and low responders, with a far greater number of genes differentially expressed by endotoxemia in high responders. Furthermore, tissue responses differed during inflammation, and we found a number of tissue-specific differentially expressed lincRNAs post-LPS, which we validated. Relative to nondifferentially expressed lincRNAs, differentially expressed lincRNAs were equally likely to be nonconserved as conserved between human and mouse, indicating that conservation is not a predictor of lincRNAs associated with human inflammatory pathophysiology. Differentially expressed genes also were enriched for signals with inflammatory and cardiometabolic disease in published genome-wide association studies. CTB-41I6.2 ( AC002091.1), a nonconserved human-specific lincRNA, is one of the top lincRNAs regulated by endotoxemia in monocytes, but not in adipose tissue. Knockdown experiments in THP-1 monocytes suggest that this lincRNA enhances LPS-induced interleukin 6 ( IL6) expression in monocytes, and we now refer to this as monocyte LPS-induced lincRNA regulator of IL6 ( MOLRIL6).

CONCLUSIONS

We highlight mRNAs and lincRNAs that represent novel candidates for modulation of innate immune and metabolic responses in humans.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT00953667.

High positivity of blood cultures obtained within two hours after shaking chills

OBJECTIVE

To determine whether the time lag between blood culture draw and the start of shaking chills is associated with blood culture positivity.

METHODS

A prospective observational study was undertaken from January 2013 to March 2015 at a referral center in Okinawa, Japan. All enrolled patients were adults with an episode of shaking chills who were newly admitted to the division of infectious diseases. The study exposure was the time lag between blood culture draw and the most recent episode of shaking chills.

RESULTS

Among patients whose blood cultures were obtained within 2h after shaking chills started, the blood culture positivity was 53.6% (52/97), whereas among patients whose blood cultures were obtained after more than 2h, the positivity was 37.6% (44/117) (p=0.019). The adjusted odds ratio of blood culture positivity for samples drawn within 2h after shaking chills was 1.88 (95% confidence interval 1.01-3.51, p=0.046). Escherichia coli were the most frequently detected bacteria (58/105).

CONCLUSIONS

The positivity of blood cultures obtained within 2h after the start of the most recent shaking chills was higher than that for blood cultures obtained after 2h.

LpA-II:B:C:D:E: a new immunochemically-defined acute phase lipoprotein in humans

Background

Previous studies of lipoproteins in patients with sepsis have been performed on density fractions isolated by conventional ultracentrifugation that are heterogeneous and provide no information about the cargo of apoproteins present in the immunochemically distinct subclasses that populate the density classes. Since apoproteins are now known to have important roles in host defense, we have separated these subclasses according to their apoprotein content and characterized their changes during experimental endotoxemia in human volunteers.

Methods

We have studied apoB- and apoA containing lipoprotein subclasses in twelve healthy male volunteers before and for 8 h after a single dose of endotoxin (ET; 2 μg/kg) to stimulate inflammation.

Results

After endotoxin, TG, TC, apoB and the apoB-containing lipoprotein cholesterol-rich subclass LpB and two of the three triglyceride-rich subclasses (TGRLP: Lp:B:C, LpB:C:E+ LpB:E) all declined. In contrast, the third TGRLP, LpA-II:B:C:D:E (“complex particle”), after reaching a nadir at 4 h rose 49% above baseline, p = .006 at 8 h and became the dominant particle in the TGRLP pool. This increment exceeds the threshold of > 25% change required for designation as an acute phase protein. Simultaneous decreases in LpA-I:A-II and LpB:C:E + LpB:E suggest that these subclasses undergo post-translational modification and contribute to the formation of new LpA-II:B:C:D:E particles.

Conclusions

We have identified a new acute phase lipoprotein whose apoprotein constituents have metabolic and immunoregulatory properties applicable to host defense that make it well constituted to engage in the APR.

Within-subject associations between inflammation and features of depression: Using the flu vaccine as a mild inflammatory stimulus

BACKGROUND

Inflammation plays a role in mood and behavior that may be relevant to identifying risk factors and treatment for depression and other stress-related illnesses. The purpose of this study was to examine whether fluctuations in inflammation following a mild immune stimulus were associated with changes in daily reported features of depression for up to a week in a healthy sample of young adults.

METHODS

Forty-one undergraduate students completed daily diaries of mood, feelings of social disconnection, sleep, and physical symptoms for one week before and after receiving the seasonal influenza vaccine. Circulating plasma interleukin-6 (IL-6) was measured via blood samples taken immediately before and one day after vaccination.

RESULTS

There was a significant increase in circulating IL-6 from pre- to post-intervention (p = .008), and there was significant variability in the magnitude of IL-6 change. Greater increases in IL-6 were associated with greater mood disturbance on post-vaccine days, specifically depressed mood and cognitive symptoms.

CONCLUSIONS

Minor increases in inflammation were associated with corresponding increases in features of depression, and these associations occurred in the absence of any physical symptoms. The influenza vaccine could be used to probe causal relationships with a high degree of ecological validity, even in high-risk and vulnerable populations, to better understand the role of inflammation in the pathogenesis of depression.

Unlocking the in vitro anti-inflammatory and antidiabetic potential of Polygonum maritimum

CONTEXT

Several Polygonum species (Polygonaceae) are used in traditional medicine in Asia, Europe and Africa to treat inflammation and diabetes.

OBJECTIVE

Evaluate the in vitro antioxidant, anti-inflammatory and antidiabetic potential of methanol and dichloromethane extracts of leaves and roots of the halophyte Polygonum maritimum L.

MATERIAL AND METHODS

Antioxidant activity was determined (up to 1 mg/mL) as radical-scavenging activity (RSA) of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), copper (CCA) and iron (ICA) chelating activities and iron reducing power (FRAP). NO production was measured in lipopolysaccharide (LPS)-stimulated macrophages for 24 h at concentrations up to 100 μg/mL and antidiabetic potential was assessed by α-amylase and α-glucosidase inhibition (up to 10 mg/mL) assays. The phytochemical composition of the extracts was determined by gas chromatography-mass spectrometry (GC-MS).

RESULTS

The methanol leaf extract had the highest activity against DPPH• (IC₅₀ = 26 μg/mL) and ABTS⁺• (IC₅₀ = 140 μg/mL), FRAP (IC₅₀ = 48 μg/mL) and CCA (IC₅₀ = 770 μg/mL). Only the dichloromethane leaf extract (LDCM) showed anti-inflammatory activity (IC₅₀ = 48 μg/mL). The methanol root (IC₅₀ = 19 μg/mL) and leaf (IC₅₀ = 29 μg/mL) extracts strongly inhibited baker's yeast α-glucosidase, but LDCM had higher rat's α-glucosidase inhibition (IC₅₀ = 2527 μg/mL) than acarbose (IC₅₀ = 4638 μg/mL). GC-MS analysis identified β-sitosterol, stigmasterol, 1-octacosanol and linolenic acid as possible molecules responsible for the observed bioactivities.

CONCLUSIONS

Our findings suggest P. maritimum as a source of high-value health promoting commodities for alleviating symptoms associated with oxidative and inflammatory diseases, including diabetes.

Are the Gut Bacteria Telling Us to Eat or Not to Eat? Reviewing the Role of Gut Microbiota in the Etiology, Disease Progression and Treatment of Eating Disorders

Traditionally recognized as mental illnesses, eating disorders are increasingly appreciated to be biologically-driven. There is a growing body of literature that implicates a role of the gut microbiota in the etiology and progression of these conditions. Gut bacteria may act on the gut–brain axis to alter appetite control and brain function as part of the genesis of eating disorders. As the illnesses progress, extreme feeding patterns and psychological stress potentially feed back to the gut ecosystem that can further compromise physiological, cognitive, and social functioning. Given the established causality between dysbiosis and metabolic diseases, an altered gut microbial profile is likely to play a role in the co-morbidities of eating disorders with altered immune function, short-chain fatty acid production, and the gut barrier being the key mechanistic links. Understanding the role of the gut ecosystem in the pathophysiology of eating disorders will provide critical insights into improving current treatments and developing novel microbiome-based interventions that will benefit patients with eating disorders.

Lifetime Modulation of the Pain System via Neuroimmune and Neuroendocrine Interactions

Chronic pain is a debilitating condition that still is challenging both clinicians and researchers. Despite intense research, it is still not clear why some individuals develop chronic pain while others do not or how to heal this disease. In this review, we argue for a multisystem approach to understand chronic pain. Pain is not only to be viewed simply as a result of aberrant neuronal activity but also as a result of adverse early-life experiences that impact an individual's endocrine, immune, and nervous systems and changes which in turn program the pain system. First, we give an overview of the ontogeny of the central nervous system, endocrine, and immune systems and their windows of vulnerability. Thereafter, we summarize human and animal findings from our laboratories and others that point to an important role of the endocrine and immune systems in modulating pain sensitivity. Taking "early-life history" into account, together with the past and current immunological and endocrine status of chronic pain patients, is a necessary step to understand chronic pain pathophysiology and assist clinicians in tailoring the best therapeutic approach.

Structural and biological characteristics of different forms of V. filiformis lipid A: use of MS to highlight structural discrepancies

Vitreoscilla filiformis is a Gram-negative bacterium isolated from spa waters and described for its beneficial effects on the skin. We characterized the detailed structure of its lipopolysaccharide (LPS) lipid A moiety, an active component of the bacterium that contributes to the observed skin activation properties. Two different batches differing in postculture cell recovery were tested. Chemical analyses and mass spectra, obtained before and after mild-alkali treatments, revealed that these lipids A share the common bisphosphorylated β-(1→6)-linked d-glucosamine disaccharide with hydroxydecanoic acid in an amide linkage. Short-chain FAs, hydroxydecanoic and dodecanoic acid, were found in a 2:1 ratio. The two lipid A structures differed by the relative amount of the hexa-acyl molecular species and phosphoethanolamine substitution of the phosphate groups. The two V. filiformis LPS batches induced variable interleukin-6 and TNF-α secretion by stimulated myelomonocytic THP-1 cells, without any difference in reactive oxygen species production or activation of caspase 3/7. Other different well-known highly purified LPS samples were characterized structurally and used as standards. The structural data obtained in this work explain the low inflammatory response observed for V. filiformis LPS and the previously demonstrated beneficial effects on the skin.

NLRP12 Inflammasome Expression in the Rat Brain in Response to LPS during Morphine Tolerance

Morphine, an effective but addictive analgesic, can profoundly affect the inflammatory response to pathogens, and long-term use can result in morphine tolerance. Inflammasomes are protein complexes involved in the inflammatory response. The nucleotide-binding oligomerization domain-like receptor (NLR) Family Pyrin Domain Containing (NLRP) 12 (NLRP12) inflammasome has been reported to have anti-inflammatory activity. In this study, we examined the expression of NLRP12 inflammasome related genes in the adult F344 rat brain in response to the bacterial endotoxin lipopolysaccharide (LPS) in the presence and absence of morphine tolerance. Morphine tolerance was elicited using the 2 + 4 morphine-pelleting protocol. On Day 1, the rats were pelleted subcutaneously with 2 pellets of morphine (75 mg/pellet) or a placebo; on Days 2 and 4 pellets were given. On Day 5, the animals were randomly assigned to receive either 250 µg/kg LPS or saline (i.p.). The expression of 84 inflammasome related genes in the rat brain was examined using a Ploymerase Chain Reaction (PCR) array. In response to LPS, there was a significant increase in the expression of the pro-inflammatory cytokine/chemokine genes interleukin-1 beta (Il-1β), interleukin-6 (Il-6), C-C motif chemokine ligand 2 (Ccl2), C-C motif chemokine ligand 7 (Ccl7), C-X-C motif chemokine ligand 1 (Cxcl1), and C-X-C motif chemokine ligand 3 (Cxcl3) and a significant decrease in the anti-inflammatory NLRP12 gene in both morphine-tolerant and placebo-control rats compared to saline-treated rats, although the changes were greater in the placebo-control animals. The Library of Integrated Network-Based Cellular Signatures’ (LINCS) connectivity map was used to analyze the list of affected genes to identify potential targets associated with the interactions of LPS and morphine tolerance. Our data indicate that, in the morphine tolerant state, the expression of NLRP12 and its related genes is altered in response to LPS and that the Vacuolar protein-sorting-associated protein 28 (VPS28), which is involved in the transport and sorting of proteins into sub-cellular vesicles, may be the key regulator of these alterations.

Colistin Reduces LPS-Triggered Inflammation in a Human Sepsis Model In Vivo: A Randomized Controlled Trial

The previously described anti-endotoxin effect of colistin has not been investigated in humans yet. We performed a randomized, double-blind, placebo-controlled crossover trial to determine the degree of colistin-driven modulation of inflammatory response in blood of lipopolysaccharide (LPS)-challenged healthy volunteers in a human endotoxemia model. After a single intravenous dose of 2.5 million IU colistin methanesulfonate, interleukin (IL)-6, IL-8, tumor necrosis factor alpha (TNF-α), and IL-1β concentrations as well as other biomarkers of inflammation such as C-reactive protein, differential leukocyte counts, and body temperature were measured up to 24 h postdose. Colistin significantly decreased the inflammatory cytokine response to LPS in blood of healthy volunteers. This effect was most evident for IL-6, IL-8, and TNF-α. This study is the first to confirm the anti-endotoxin effect of colistin in humans in vivo. Further studies might increase our knowledge on the interaction between colistin and the effectors of the immune system.

Tumor-Derived Factors and Reduced p53 Promote Endothelial Cell Centrosome Over-Duplication

Approximately 30% of tumor endothelial cells have over-duplicated (>2) centrosomes, which may contribute to abnormal vessel function and drug resistance. Elevated levels of vascular endothelial growth factor A induce excess centrosomes in endothelial cells, but how other features of the tumor environment affect centrosome over-duplication is not known. To test this, we treated endothelial cells with tumor-derived factors, hypoxia, or reduced p53, and assessed centrosome numbers. We found that hypoxia and elevated levels of bone morphogenetic protein 2, 6 and 7 induced excess centrosomes in endothelial cells through BMPR1A and likely via SMAD signaling. In contrast, inflammatory mediators IL-8 and lipopolysaccharide did not induce excess centrosomes. Finally, down-regulation in endothelial cells of p53, a critical regulator of DNA damage and proliferation, caused centrosome over-duplication. Our findings suggest that some tumor-derived factors and genetic changes in endothelial cells contribute to excess centrosomes in tumor endothelial cells.

Why sickness hurts: A central mechanism for pain induced by peripheral inflammation

Low-grade systemic inflammation has been implicated in chronic pain, as well as in comorbid diseases like depression and fatigue. We have previously shown that women's pain perception and regulation is more affected by systemic inflammation than that of men. Here we investigated the neural substrates underlying these effects using an fMRI paradigm previously employed in a clinical population. Fifty-one participants (29 women) were injected with 0.6ng/kg lipopolysaccharide (LPS) or saline to induce a peripheral inflammatory response. The subjects were then tested with a pressure pain fMRI paradigm designed to capture descending pain inhibitory activity 2h after injection, and blood was sampled for cytokine analysis. The subjects injected with LPS became more pain sensitive compared to the placebo group, and the heightened pain sensitivity was paralleled by decreased activity in the ventrolateral prefrontal cortex and the rostral anterior cingulate cortex (rACC) compared to placebo; areas involved in descending pain regulation. The LPS group also had higher activity in the anterior insular cortex, an area underpinning affective and interoceptive pain processing. Women displayed overall less pain-evoked rACC activity compared to men, which may have rendered women less resilient to immune provocation, possibly explaining sex differences in LPS-induced pain sensitivity. Our findings elucidate the pain-related brain circuits affected by experimental peripheral inflammation, strengthening the theoretical link between systemic inflammation and weakened pain regulation in chronic pain disorders. The results further suggest a possible mechanism underlying the female predominance in many chronic pain disorders.

Induction of tumor necrosis factor α and interleukin-1β in subcutaneously implanted chamber by lipopolysaccharide

Lipopolysaccharide (LPS) is the major component of the outermost membrane of Gram-negative bacteria and is considered to be one of the major virulence factors of these bacteria. While the effect of systemic injection of LPS is well characterized, the characterization of cytokine secretion in response to local injection of LPS is lacking. The present study was designed to determine the local production of tumor necrosis factor α (TNFα) and interleukin-1β (IL-1β) over a 4 day period following injection of LPS into subcutaneous implanted chambers in mice. Mice were challenged by a single or repeated injection of Salmonella typhosa LPS into the chambers. Chamber fluids were aspirated at different time intervals and were used for assessment of leukocyte and cytokine levels. A single injection of LPS was found to induce cell influx into the chamber which peaked after 4 h. TNFα and IL-1β levels increased rapidly, reaching their maximum levels within 4 h. After 24 h, TNFα levels declined markedly and were undetectable at 48 and 96 h. TNFα mRNA levels in the sedimented cells followed a similar pattern. In contrast, IL-1β showed a more gradual decrease with levels significantly different from baseline still being present 96 h post-LPS challenge. Four consecutive daily injections of LPS into the chambers resulted in undetectable levels of TNFα in the chamber fluid, while significant levels of IL-1β were detected. These levels were significantly higher than the levels of IL-1β in the chamber fluid 96 h after a single injection and approximately 60% of the levels measured 24 h after a single intra-chamber injection of LPS. The results emphasize the difference between single and repeated exposure to LPS in vivo, and suggest a role for TNFα in the initial phase of the local inflammatory response and for IL-1β in the later phase.

Endotoxin-induced desensitization of THP-1 cells is not associated with altered G protein binding or content

In rats endotoxin tolerance is characterized by decreased endotoxin-stimulated peritoneal macrophage arachidonic acid metabolism and decreased GTP binding protein function. The hypothesis that THP-1 cells can be altered in a similar manner by pretreatment with endotoxin was tested. These studies examined endotoxin's ability to stimulate eicosanoid and tumor necrosis factor α (TNFα) in control and desensitized THP 1 cells. Additionally, membrane GTPγ 35S binding and Western blot analyses with specific antisera to G i1,2α, Gi3a, Gαcommon, and the β subunit of G in control and endotoxin-desensitized THP-1 cells were assessed. Endotoxin (10 μg/ml) stimulated thromboxane (Tx) B2 production in THP-1 cells. Pretreatment with pertussis toxin (PT), resulted in significant inhibition of TxB2 production at concentrations not inhibited by equimolar concentrations of PT-B protomer. The latter observations suggest a role of PT-sensitive G protein in endotoxin activation of THP-1 cells. Pre-exposure to endotoxin (1 μg/ml) for 18 h desensitized THP-1 cells to endotoxin-stimulated TxB2 production and endotoxin-stimulated TNFα. To determine if endotoxin pretreatment affects G protein function, THP-1 cell membranes were isolated from endotoxin pretreated and control cells for equilibrium binding with GTPγ35S, a nonhydrolyzable analog of GTP. Neither the total number of binding sites (Bmax) nor the dissociation constant (Kd) for GTPγ35S in desensitized THP-1 cells were significantly different from those of control cells. PT-catalyzed ADP-ribosylation of G proteins in control and LPS-desensitized THP-1 cells demonstrated no difference in the quantity of G protein labelled versus desensitized cells. Immunoblots also showed no difference between control and desensitized cells in the membrane content of specific heterotrimeric G proteins. The data demonstrate that pre-exposure to endotoxin desensitizes the cells subsequent endotoxin stimulation of mediator production. However, unlike the in vivo rat model, this is not associated with a decrease in G protein binding or content.

Masking of endotoxin in surfactant samples: Effects on Limulus-based detection systems

Over the last few decades Limulus Amebocyte Lysate (LAL) has been the most sensitive method for the detection of endotoxins (Lipopolysaccharides) and is well accepted in a broad field of applications. Recently, Low Endotoxin Recovery (LER) in biopharmaceutical drug products has been noticed, whereby the detection of potential endotoxin contaminations is not ensured. Notably, most of these drug products contain surfactants, which can have crucial effects on the detectability of endotoxin. In order to analyze the driving forces of LER, endotoxin detection in samples containing nonionic surfactants in various buffer systems was investigated. The results show that the process of LER is kinetically controlled and temperature-dependent. Furthermore, only the simultaneous presence of nonionic surfactants and components capable of forming metal complexes resulted in LER. In addition, capacity experiments show that even hazardous amounts of endotoxin can remain undetectable within such formulation compositions. In conclusion, the LER phenomenon is caused by endotoxin masking and not by test interference. In this process, the supramolecular structure of endotoxin is altered and exhibits only a limited susceptibility in binding to the Factor C of Limulus-based detection systems. We propose a two-step mechanism of endotoxin masking by complex forming agents and nonionic surfactants.

Thrombin Generation by Exposure of Blood to Endotoxin: A Simple Model to Study Disseminated Intravascular Coagulation

Pathologic disseminated intravascular coagulation (PDIC) is a serious complication in sepsis. In an in-vitro system consisting of incubation of fresh citrated blood with lipopolysaccharides (LPS) or glucans and subsequent plasma recalcification plasmatic thrombin was quantified. Five hundred microliters of freshly drawn citrated blood of healthy donors were incubated with up to 800 ng/mL LPS ( Escherichia coli) or up to 80 μg/mL Zymosan A (ZyA; Candida albicans) for 30 minutes at room temperature (RT). The samples were centrifuged, and 30 μL plasma were recalcified with 1 volume or less of CaCl2 (25 μmoles Ca2+/mL plasma). After 0 to 12 minutes (37°C), 20 μL 2.5 M arginine, pH 8.6, were added. Thirty microliters 0.9 m M HD-CHG-Ala-Arg-pNA in 2.3 M arginine were added, and the absorbance increase at 405 nm was determined. Fifty microliters plasma were also incubated with 5 μL 250 m M CaCl2 for 5, 10, or 15 minutes (37°C). Fifty microliters 2.5 M arginine stops coagulation, and 50 μL 0.77 m M HD-CHG-Ala-Arg-pNA in 2.3 M arginine starts the thrombin detection. The standard was 1 IU/mL thrombin in 7% human albumin instead of plasma. Arginine was also added in the endotoxin exposure time (EET) or in the plasma coagulation reaction time (CRT). Tissue factor (TF)-antigen and soluble CD14 were determined. LPS at blood concentrations greater than 10 ng/mL or ZyA at greater than 1 μg/mL severalfold enhance thrombin generation, when the respective plasmas are recalcified. After 30 minutes EET at RT, the thrombin activity at 12 minutes CRT generated by the addition of 200 ng/mL LPS or 20 μg/mL ZyA is approximately 200 mIU/mL compared to approximately 20 mIU/mL without addition of endotoxin, or compared to about 7 mIU/mL thrombin at 0 minutes CRT. Arginine added to blood or to plasma inhibits thrombin generation; the inhibitory concentration 50% (IC 50) is approximately 15 m M plasma concentration. Endotoxin incubation of blood increases neither TF nor sCD14. This assay allows the study of the hemostasis alteration in PDIC, particularly in PDIC by sepsis. The thrombin generated by blood plus endotoxin incubation and plasma recalcification suggests that the contact phase of coagulation; e.g., triggered by cell components of (phospholipase-) lysed cells such as monocyte or endothelium DNA or phospholipid-vesicles (microparticles), is of primary pathologic importance in sepsis-PDIC. Arginine at plasma concentrations of 10 to 50 m M might be a new therapeutic for sepsis-PDIC.

Reparixin, a Specific Interleukin-8 Inhibitor, Has No Effects on Inflammation during Endotoxemia

Reparixin antagonizes interleukin-8 (IL-8) on the level of signal transduction in vitro. We hypothesized that IL-8 mediates some of the reactions occurring during acute inflammation and specifically that IL-8 may be a mediator of endotoxin induced neutrophilia. We therefore tested the effects of reparixin on humoral and cellular parameters in LPS-induced acute systemic inflammation. The study is a randomized (3:2 active:placebo), double-blind, placebo-controlled parallel group trial. Twenty healthy male volunteers randomly received either reparixin (12) or placebo (8) intravenously. One hour after the start of reparixin/placebo infusion a bolus of 2 ng/kg endotoxin was infused over 1–2 min. Blood samples were obtained over 24 h. Reparixin, being metabolized to ibuprofen, suppressed serum thromboxane B2 levels by 78% compared to baseline and control at 8 h. LPS-induced neutrophilia was not significantly affected by reparixin in human volunteers. Consistently, reparixin did not alter the lymphocyte or monocyte counts and had no effect on LPS-induced systemic inflammation as measured by tumor necrosis factor alpha (TNF-α) or interleukin-6 (IL-6) release. Regulation of IL-8 receptors CXCR1 and 2 and the degranulation marker CD11b showed the expected kinetics. Reparixin had no effect on thrombin formation as measured by prothrombin fragment (F1+2). In conclusion, our study showed that reparixin was safe but had no impact on endotoxin induced inflammation. In contrast to previous studies with its metabolite ibuprofen, reparixin does not enhance inflammation in this model.

Anti-inflammatory effects of Lactobacillus brevis K65 on RAW 264.7 cells and in mice with dextran sulphate sodium-induced ulcerative colitis

Lactic acid bacteria (LAB) with anti-inflammatory effects may be beneficial to the prevention or treatment for inflammation-related diseases, such as inflammatory bowel diseases. In an in vitro assay, heat-killed Lactobacillus brevis K65 (K65) reduced lipopolysaccharide-induced production of nitric oxide, tumour necrosis factor (TNF)-α and prostaglandin E2 in RAW 264.7 cells. In RAW 264.7 cells stably expressing an ind=ucible nitric oxide synthase (iNOS) reporter, viable K65 showed greater inhibition of iNOS production than its heat-killed form. In order to further examine the in vivo anti-inflammatory effect of K65, viable K65 was orally administered to BALB/c mice before and during the period of dextran sulphate sodium (DSS)-induced ulcerative colitis (UC). K65 improved UC symptoms, including reduced the levels of the pro-inflammatory cytokines, TNF-α, interleukin (IL)-6 and IL-1β, and lowered the activity of myeloperoxidase. Furthermore, K65 inhibited TNF-α, cyclo-oxygenase 2, forkhead box P3, and Toll-like receptor 4 mRNA expression in the colonic tissue of DSS-induced UC mice. Taken together, K65, a LAB with in vitro anti-inflammatory activity showed preventive effects on mice with DSS-induced UC by lowering the expression of inflammatory molecules.

Identification of Adjuvantic Activity of Amphotericin B in a Novel, Multiplexed, Poly-TLR/NLR High-Throughput Screen

Small-molecule agonists have been identified for TLR7, TLR8, TLR4 and TLR2 thus far, and chemotypes other than those of canonical ligands are yet to be explored for a number of innate immune receptors. The discovery of novel immunostimulatory molecules would enhance the repertoire of tools available for interrogating innate immune effector mechanisms, and provide additional venues for vaccine adjuvant development. A multiplexed, reporter gene-based high-throughput assay capable of detecting agonists of TLR2, TLR3, TLR4, TLR5, TLR7, TLR8, TLR9, NOD1 and NOD2 was utilized in screening 123,943 compounds, in which amphotericin B (AmpB) and nystatin were identified as prominent hits. The polyene antifungal agents act as TLR2- and TLR4-agonists. The TLR4-stimulatory activity of AmpB was similar to that of monophosphoryl lipid A, suggestive of TRIF-biased signaling. The adjuvantic activity of AmpB, at a dose of 100 micrograms, was comparable to several other candidate adjuvants in rabbit models of immunization. These results point to its potential applicability as a safe and effective adjuvant for human vaccines.

Risks associated with endotoxins in feed additives produced by fermentation

Increasingly, feed additives for livestock, such as amino acids and vitamins, are being produced by Gram-negative bacteria, particularly Escherichia coli. The potential therefore exists for animals, consumers and workers to be exposed to possibly harmful amounts of endotoxin from these products. The aim of this review was to assess the extent of the risk from endotoxins in feed additives and to calculate how such risk can be assessed from the properties of the additive. Livestock are frequently exposed to a relatively high content of endotoxin in the diet: no additional hazard to livestock would be anticipated if the endotoxin concentration of the feed additive falls in the same range as feedstuffs. Consumer exposure will be unaffected by the consumption of food derived from animals receiving endotoxin-containing feed, because the small concentrations of endotoxin absorbed do not accumulate in edible tissues. In contrast, workers processing a dusty additive may be exposed to hazardous amounts of endotoxin even if the endotoxin concentration of the product is low. A calculation method is proposed to compare the potential risk to the worker, based on the dusting potential, the endotoxin concentration and technical guidance of the European Food Safety Authority, with national exposure limits.

A novel method to determine residual detergent in biological samples post endotoxin reduction treatment and evaluation of strategies for subsequent detergent removal

Endotoxin removal using detergent washes and extractions are well-established, efficient, and cost-effective methods; however, removing residual detergent post treatment has been shown to be a challenge. In this communication, we show a simple and fast method for determining the detergent concentration in a protein solution post treatment and highlight strategies for detergent removal to achieve levels below the critical micelle concentration (CMC), the minimum concentration at which detergent micelles form.

In vivo porcine lipopolysaccharide inflammation models to study immunomodulation of drugs

Lipopolysaccharide (LPS), a structural part of the outer membrane of Gram-negative bacteria, is one of the most effective stimulators of the immune system and has been widely applied in pigs as an experimental model for bacterial infection. For this purpose, a variety of Escherichia coli serotypes, LPS doses, routes and duration of administration have been used. LPS administration induces the acute phase response (APR) and is associated with dramatic hemodynamic, clinical and behavioral changes in pigs. Pro-inflammatory cytokines, including tumor necrosis factor α (TNF-α), interleukin (IL)-1 and IL-6 are involved in the induction of the eicosanoid pathway and the hepatic production of acute phase proteins, including C-reactive protein (CRP), haptoglobin (Hp) and pig major acute phase protein (pig-MAP). Prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) play a major role in the development of fever and pulmonary hypertension in LPS-challenged pigs, respectively. The LPS-induced APR can be modulated by drugs. Steroidal and nonsteroidal anti-inflammatory drugs ((N)SAIDs) possess anti-inflammatory, antipyretic and analgesic properties through (non)-selective central and peripheral cyclooxygenase (COX) inhibition. Antimicrobial drugs, especially macrolide antibiotics, which are commonly used in veterinary medicine for the treatment of bacterial respiratory diseases, have been recurrently reported to exert clinically important immunomodulatory effects in human and murine research. To investigate the influence of these drugs on the clinical response, production of pro-inflammatory cytokines, acute phase proteins (APP) and the course of the febrile response in pigs, in vivo LPS inflammation models can be applied. Yet, to date, in vivo research on the immunomodulatory properties of antimicrobial drugs in these models in pigs is largely lacking. This review provides acritical overview of the use of in vivo porcine E. coli LPS inflammation models for the study of the APR, as well as the potential immunomodulatory properties of anti-inflammatory and antimicrobial drugs in pigs.

Activation of innate immunity modulates insulin sensitivity, glucose effectiveness and pancreatic β-cell function in both African ancestry and European ancestry healthy humans

OBJECTIVE

Insulin resistance is a risk factor for type 2 diabetes, and is associated with inflammatory cardiometabolic disease. Given differences between African ancestry (AA) and European ancestry (EA) in the epidemiology of type 2 diabetes as well as in response to inflammatory stress, we investigated potential race differences in glucose homeostasis responses during experimental endotoxemia in humans.

METHODS

Healthy volunteers (age 18-45 years, BMI 18-30 kg/m(2), 47% female, African-ancestry (AA, n=42) and European-ancestry (EA, n=106)) were recruited as part of the Genetics of Evoked Responses to Niacin and Endotoxemia (GENE) Study. Subjects underwent an inpatient endotoxin challenge (1 ng/kg LPS) and two frequently-sampled intravenous glucose tolerance tests (FSIGTT). Insulin and glucose values obtained during FSIGTT pre- and 24-hours post-LPS were analyzed using the minimal model.

RESULTS

FSIGTT derived insulin sensitivity index (SI), disposition index (DI) and glucose effectiveness (SG) decreased significantly following LPS (p<0.0001) while the acute insulin response to glucose (AIR(g)) increased (p<0.0001). Although expected race differences were observed in glucose homeostasis parameters at baseline prior to LPS e.g., lower SI (2.5 vs. 4.1 μU/L/min, p<0.0001) but higher AIR(g) (median 848 vs. 290 μU/L/min, p<0.0001) in AA vs. EA, the changes in glucose homeostasis responses to LPS were directionally and proportionally consistent across race e.g., SI median -35% in EA and -29% in AA and AIR(g) median +17% in EA and +26% in AA.

CONCLUSION

Both EA and AA samples modulated glucose and insulin homeostasis similarly during endotoxemia.

IMPLICATIONS

Race differences in response to environmental inflammatory stress are unlikely to be a substantial contributor to the observed difference in diabetes incidence and complications between EA and AA.

Removal of endotoxins from bacteriophage preparations by extraction with organic solvents

Lipopolysaccharide (LPS, endotoxin, pyrogen) constitutes a very troubling contaminant of crude phage lysates produced in Gram-negative bacteria. Toxicity of LPS depends on the strong innate immunity response including the cytokines. Therefore, its removal is important for bacteriophage applications. In this paper, we present a procedure for extractive removal of endotoxin from bacteriophage preparations with water immiscible solvents (1-octanol or 1-butanol). During extraction most of the phage lytic activity is retained in the aqueous phase, while endotoxin accumulates in the organic solvent. The levels of endotoxin (expressed as endotoxin units, EU) in the aqueous bacteriophage-containing fraction determined by limulus amebocyte lysate or EndoLISA assay were exceptionally low. While the initial endotoxin levels in the crude phage lysates ranged between 10³ and 10⁵ EU/ml the average level after organic extraction remaining in the aqueous fraction was 5.3 EU/ml. These values when related to phage titers decreased from 10³-10⁵ EU/10⁹ PFU (plaque forming units) down to an average of 2.8 EU/10⁹ PFU. The purification procedure is scalable, efficient and applicable to all the bacteriophages tested: T4, HAP1 (E. coli) and F8 (P. aeruginosa).

Human experimental endotoxemia in modeling the pathophysiology, genomics, and therapeutics of innate immunity in complex cardiometabolic diseases

Inflammation is a fundamental feature of several complex cardiometabolic diseases. Indeed, obesity, insulin resistance, metabolic dyslipidemia, and atherosclerosis are all closely linked inflammatory states. Increasing evidence suggests that the infectious, biome-related, or endogenous activation of the innate immune system may contribute to the development of metabolic syndrome and cardiovascular disease. Here, we describe the human experimental endotoxemia model for the specific study of innate immunity in understanding further the pathogenesis of cardiometabolic disease. In a controlled, experimental setting, administration of an intravenous bolus of purified Escherichia coli endotoxin activates innate immunity in healthy human volunteers. During endotoxemia, changes emerge in glucose metabolism, lipoprotein composition, and lipoprotein functions that closely resemble those observed chronically in inflammatory cardiovascular disease risk states. In this review, we describe the transient systemic inflammation and specific metabolic consequences that develop during human endotoxemia. Such a model provides a controlled induction of systemic inflammation, eliminates confounding, undermines reverse causation, and possesses unique potential as a starting point for genomic screening and testing of novel therapeutics for treatment of the inflammatory underpinning of cardiometabolic disease.

Characterization of Toll-like receptor-4 (TLR-4) in the spleen and thymus of Swiss albino mice and its modulation in experimental endotoxemia

Expression of innate immune receptors varies among organs and species and within different strains among the same species; thus, periodic classification of different pattern recognition receptors in the available strains is necessary to initiate different therapeutic approaches to combat inflammation. On characterization of TLR-4 in spleen and thymus of Swiss albino mice—with no reports of TLR-4 expression—induced with endotoxemia, it was found that the mode of expression varied among the organs at both mRNA and protein level in a time-dependent manner. Their functionality was verified by measuring proinflammatory and anti-inflammatory cytokines. In the in vitro study using isolated macrophages and lymphocytes from the same organs, the expression of TLR-4 after a shorter period of LPS stimulation was verified. The results substantiated the potent role of macrophage on LPS challenge compared to lymphocytes. The diverse pattern of TLR-4 expression on different cell population indicated their distinct functional activity in LPS-endotoxemia. It may be hypothesized that the expression patterns of TLR-4 could be different based on the anatomical localization and the varying bacterial milieu or bacterial endotoxin encountered in each anatomical location. Thus, blocking TLR-4 or administering IL-6 or IL-10 might impart protection against endotoxemia in the clinical field.