Role of lipopolysaccharide (LPS), interleukin-1, interleukin-6, tumor necrosis factor, and dexamethasone in regulation of LPS-binding protein expression in normal hepatocytes and hepatocytes from LPS-treated rats

Serum bile acids profiles are altered without change of the gut microbiota composition following a seven-day prednisolone therapy in severe alcoholic hepatitis

Severe Alcoholic Hepatitis (sAH) is an acute form of liver injury caused by chronic and heavy alcohol drinking. A one-month corticosteroids course is the only sAH reference treatment, and its interactions with the Gut Microbiota (GM), which is a key contributor to liver injury, remain unknown. To evaluate the evolution of the GM in sAH patients, we retrospectively investigated the composition of the GM of 27 sAH patients at the Amiens University Hospital before (D0) and after (D7) a 7-day corticotherapy course using fecal metagenomics sequencing. We also quantified fecal Short-Chain Fatty Acids (SCFA) and fecal and serum Bile Acids (BA), as well as serum Lipopolysaccharide-Binding Protein (LBP). Overall, the community and taxonomical analyses did not reveal any GM evolution between D0 and D7, nor did the SCFA profiles analysis. However, in serum but not fecal samples, the ratio of glyco-conjugated to tauro-conjugated BA was significantly reduced at D7, independently of the response to treatment, while two BA were enriched in non-responder patients. LBP concentration significantly diminished between D0 and D7, which may indicate an improvement of the gut barrier. The stability of the GM of sAH is interesting in the perspective of new treatments based on GM modulation.

Comparing the gut microbiome of obese, African American, older adults with and without mild cognitive impairment

Those with mild cognitive impairment (MCI), a precursor to dementia, have a gut microbiome distinct from healthy individuals, but this has only been shown in healthy individuals, not in those exhibiting several risk factors for dementia. Using amplicon 16S rRNA gene sequencing in a case-control study of 60 older (ages 55-76), obese, predominately female, African American adults, those with MCI (cases) had different gut microbiota profiles than controls. While microbial community diversity was similar between cases and controls, the abundances of specific microbial taxa weren't, such as Parabacteroides distasonis (lower in cases) and Dialister invisus (higher in cases). These differences disappeared after adjusting for markers of oxidative stress and systemic inflammation. Cognitive scores were positively correlated with levels of Akkermansia muciniphila, a bacterium associated with reduced inflammation. Our study shows that gut microbial composition may be associated with inflammation, oxidative stress, and MCI in those at high risk for dementia.

Morphological Assessment and Biomarkers of Low-Grade, Chronic Intestinal Inflammation in Production Animals

Simple Summary

Production animals are continuously exposed to environmental and dietary factors that might induce a state of low-grade, chronic intestinal inflammation. This condition compromises the productive performance and well-fare of these animals, requiring studies to understand what causes it and to develop control strategies. An intestinal inflammatory process is generally associated with alterations in the structure and functionality of its wall, resulting in the release of cellular components into the blood and/or feces. These components can act as biomarkers, i.e., they are measured to identify and quantify an inflammatory process without requiring invasive methods. In this review we discuss the mechanisms of low-grade inflammation, its effects on animal production and sustainability, and the identification of biomarkers that could provide early diagnosis of this process and support studies of useful interventional strategies.

Abstract

The complex interaction between the intestinal mucosa, the gut microbiota, and the diet balances the host physiological homeostasis and is fundamental for the maximal genetic potential of production animals. However, factors such as chemical and physical characteristics of the diet and/or environmental stressors can continuously affect this balance, potentially inducing a state of chronic low-grade inflammation in the gut, where inflammatory parameters are present and demanding energy, but not in enough intensity to provoke clinical manifestations. It’s vital to expand the understanding of inflammation dynamics and of how they compromise the function activity and microscopic morphology of the intestinal mucosa. These morphometric alterations are associated with the release of structural and functional cellular components into the feces and the blood stream creating measurable biomarkers to track this condition. Moreover, the identification of novel, immunometabolic biomarkers can provide dynamic and predictors of low-grade chronic inflammation, but also provide indicators of successful nutritional or feed additive intervention strategies. The objective of this paper is to review the mechanisms of low-grade inflammation, its effects on animal production and sustainability, and the biomarkers that could provide early diagnosis of this process and support studies of useful interventional strategies.

High-Precision Isotopic Analysis of Cu and Fe via Multi-Collector Inductively Coupled Plasma-Mass Spectrometry Reveals Lipopolysaccharide-Induced Inflammatory Effects in Blood Plasma and Brain Tissues

The concentration and the isotopic composition of the redox-active essential elements Cu and Fe were investigated in blood plasma and specific brain regions (hippocampus, cortex, brain stem and cerebellum) of mice to assess potential alterations associated with sepsis-associated encephalopathy induced by lipopolysaccharide (LPS) administration. Samples were collected from young (16-22 weeks) and aged (44-65 weeks) mice after intraperitoneal injection of the LPS, an endotoxin inducing neuroinflammation, and from age- and sex-matched controls, injected with phosphate-buffered saline solution. Sector-field single-collector inductively coupled plasma-mass spectrometry was relied upon for elemental analysis and multi-collector inductively coupled plasma-mass spectrometry for isotopic analysis. Significant variations were observed for the Cu concentration and for the Cu and Fe isotope ratios in the blood plasma. Concentrations and isotope ratios of Cu and Fe also varied across the brain tissues. An age- and an inflammatory-related effect was found affecting the isotopic compositions of blood plasma Cu and cerebellum Fe, whereas a regional Cu isotopic redistribution was found within the brain tissues. These findings demonstrate that isotopic analysis of essential mineral elements picks up metabolic changes not revealed by element quantification, making the two approaches complementary.

Altered Intestinal Permeability Biomarkers in Schizophrenia: A Possible Link with Subclinical Inflammation

Background and Purpose

Emerging studies have shown that gut-derived endotoxins might play a role in intestinal and systemic inflammation. Although the significance of intestinal permeability in modulating the pathogenesis of Schizophrenia (SCZ) is recognized, not much data on the specific role of intestinal permeability biomarkers, viz., zonulin, lipopolysaccharide-binding protein (LBP), and intestinal alkaline phosphatase (IAP) in SCZ is available. Therefore, we measured the plasma levels of zonulin, LBP, and IAP and its correlation with neutrophil-to-lymphocyte ratio (NLR); a marker of systemic inflammation in patients with SCZ.

Methods

We recruited 60 individuals, patients with SCZ (n = 40) and healthy controls (n = 20), from a large tertiary neuropsychiatry center. Plasma levels of zonulin, IAP, and LBP were quantified by enzyme-linked immunosorbent assay.

Results

Plasma levels of both LBP and zonulin were significantly increased (P <0.05), whereas the IAP levels (P <0.05) were significantly decreased in patients with SCZ compared to healthy controls. Pearson correlation analysis revealed that zonulin and LBP had a significant positive correlation with NLR, and IAP negatively correlated with NLR. Individuals with SCZ had higher independent odds of zonulin [odds ratio (OR): 10.32, 95% CI: 1.85-57.12], LBP [OR: 1.039, 95% CI: 1.02-1.07], and IAP [OR: 0.643, 95% CI: 0.471-0.879], even after adjusting for potential confounders.

Conclusion

Our study demonstrates an association of zonulin, LBP, and IAP in Asian Indian SCZ patients and correlates with NLR. Our results indicate that low-grade inflammation induced by metabolic endotoxemia might be implicated in the pathoetiology of SCZ.

Stressor-Induced Reduction in Cognitive Behavior is Associated with Impaired Colonic Mucus Layer Integrity and is Dependent Upon the LPS-Binding Protein Receptor CD14

Purpose

Commensal microbes are impacted by stressor exposure and are known contributors to cognitive and social behaviors, but the pathways through which gut microbes influence stressor-induced behavioral changes are mostly unknown. A murine social stressor was used to determine whether host-microbe interactions are necessary for stressor-induced inflammation, including neuroinflammation, that leads to reduced cognitive and social behavior.

Methods

C57BL/6 male mice were exposed to a paired fighting social stressor over a 1 hr period for 6 consecutive days. Y-maze and social interaction behaviors were tested following the last day of the stressor. Serum cytokines and lipopolysaccharide binding protein (LBP) were measured and the number and morphology of hippocampal microglia determined via immunohistochemistry. Intestinal mucous thickness and antimicrobial peptide expression were determined via fluorescent staining and real-time PCR (respectively) and microbial community composition was assessed using 16S rRNA gene amplicon sequencing. To determine whether the microbiota or the LBP receptor (CD14) are necessary for stressor-induced behavioral changes, experiments were performed in mice treated with a broad-spectrum antibiotic cocktail or in CD14-/- mice.

Results

The stressor reduced Y-maze spontaneous alternations, which was accompanied by increased microglia in the hippocampus, increased circulating cytokines (eg, IL-6, TNF-α) and LBP, and reduced intestinal mucus thickness while increasing antimicrobial peptides and cytokines. These stressor-induced changes were largely prevented in mice given broad-spectrum antibiotics and in CD14-/- mice. In contrast, social stressor-induced alterations of social behavior were not microbe-dependent.

Conclusion

Stressor-induced cognitive deficits involve enhanced bacterial interaction with the intestine, leading to low-grade, CD14-dependent, inflammation.

Immune Response to an Acute Moderate Dose of Alcohol in Healthy Young Adults

Prior research on alcohol and the immune system has tended to focus on binge doses or chronic heavy drinking. The aim of this single-session preliminary study was to characterize immune response to moderate alcohol (0.60 g alcohol per kilogram body weight) in healthy, nonchronic drinkers. The sample (N = 11) averaged 26.6 years of age and was balanced in gender. Plasma samples were collected at baseline and 1, 2 and 3 hours postconsumption. Markers of microbial translocation [lipopolysaccharide (LPS)] and innate immune response [LPS-binding protein (LBP), soluble cluster of differentiation 14 (sCD14), and selected cytokines] were measured using immunoassays. Participants completed self-report questionnaires on subjective alcohol response and craving. Linear mixed models were used to assess changes in biomarkers and self-report measures. Breath alcohol concentration peaked at 0.069 ± 0.008% 1 hour postconsumption. LPS showed a significant linear decrease. LBP and sCD14 showed significant, nonlinear (U-shaped) trajectories wherein levels decreased at 1 hour then rebounded by 3 hours. Of nine cytokines tested, only MCP-1 and IL-8 were detectable in ≥50% of samples. IL-8 did not change significantly. MCP-1 showed a significant linear decrease and also accounted for significant variance in alcohol craving, with higher levels associated with stronger craving. Results offer novel evidence on acute immune response to moderate alcohol. Changes in LBP and sCD14, relative to LPS, may reflect their role in LPS clearance. Results also support further investigation into the role of MCP-1 in alcohol craving. Limitations include small sample size and lack of a placebo condition.

The Expanding Role of Biomarkers in Diagnosing Infection in Total Joint Arthroplasty: A Review of Current Literature

Consistent diagnosis of periprosthetic infection in total joint arthroplasty continues to elude the orthopedic surgeon because no gold standard test exists. Therefore clinicians must rely on a combination of tests to help aid the diagnosis. The expanding role of biomarkers has shown promising results to more accurately diagnose an infection when combined with clinical suspicion and bacterial culture testing. This paper reviews the diagnostic capabilities of the most current serum and synovial biomarkers as well as next generation sequencing in the setting of periprosthetic joint infection. Future research and high-powered studies will be necessary to determine sensitivity and specificity of each biomarker.

Lipopolysaccharide Administration Alters Extracellular Vesicles in Cell Lines and Mice

Extracellular vesicles (EVs) play a fundamental role in cell and infection biology and have the potential to act as biomarkers for novel diagnostic tools. In this study, we explored the in vitro impact of bacterial lipopolysaccharide administration on cell lines that represents a target for bacterial infection in the host. Administration of lipopolysaccharide at varying concentrations to A549 and BV-2 cell lines caused only modest changes in cell death, but EV numbers were significantly changed. After treatment with the highest concentration of lipopolysaccharide, EVs derived from A549 cells packaged significantly less interleukin-6 and lysosomal-associated membrane protein 1. EVs derived from BV-2 cells packaged significantly less tumor necrosis factor after administration of lipopolysaccharide concentrations of 0.1 µg/mL and 1 µg/mL. We also examined the impact of lipopolysaccharide administration on exosome biogenesis and cargo composition in BALB/c mice. Serum-isolated EVs from lipopolysaccharide-treated mice showed significantly increased lysosomal-associated membrane protein 1 and toll-like receptor 4 levels compared with EVs from control mice. In summary, this study demonstrated that EV numbers and cargo were altered using these in vitro and in vivo models of bacterial infection.

Association of serum lipopolysaccharide-binding protein level with sensitization to food allergens in children

Lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase reactant that mediates innate immune responses triggered by LPS. Recent studies indicated a positive correlation of circulating LBP level with chronic low-grade inflammation, a condition present in many non-communicable diseases. We determined the association of serum LBP concentration with allergic sensitization in a general pediatric population. Serum LBP was measured in a sample of children (n = 356; mean age = 9.6 ± 0.2 years) in this population-based cross-sectional study. Skin prick tests (SPTs) were performed to assess allergic sensitization to 22 common inhalant and food allergens. One hundred and seven children (30.1%) were nonsensitized, 160 (44.9%) were monosensitized, and 89 (25.0%) were polysensitized. Children who were mono- or polysensitized had a significantly higher median serum LBP level (25.5 ng/mL, inter-quartile range [IQR] 20.3-30.7) than those who were nonsensitized (20.3 ng/mL, IQR = 14.81-25.8, P < 0.0001). Multivariate logistic regression analysis with adjustment for confounders indicated that serum LBP level was positively associated with allergic sensitization overall (adjusted odds ratio [aOR] 1.041; 95% CI 1.007-1.076, P = 0.016), with sensitization to food allergens in particular (aOR 1.080, 95% CI 1.029-1.133, P = 0.002), but not with sensitization to aeroallergens (aOR 1.010, 95% CI 0.982-1.040, P = 0.467). LBP level was not associated with allergic diseases after adjustment. We suggest the possibility of sensitization to food allergens may be related to gut-derived low-grade inflammation, and large sized longitudinal investigations are needed to elucidate the relationship.

Gender differences in the link between depressive symptoms and ex vivo inflammatory responses are associated with markers of endotoxemia

Depressive symptoms are often linked with higher inflammation and inflammatory responses, although these associations are not always consistent. In a recent study (N = 160, 25–65 years, 67% women), our group reported gender differences relevant to this association: In men higher depressive symptoms were related to heightened ex vivo inflammatory responses to lipopolysaccharide (LPS), whereas in women higher depressive symptoms were related to attenuated inflammatory responses. In the present manuscript, we investigate markers of endotoxemia – i.e., markers of the presence of endotoxin in the blood, presumably due to bacterial translocation from the gut – as factors that elicit gender-dependent immune responses that may be associated with links between depressive symptoms and inflammation. We examined ex vivo inflammatory responses in whole blood via a composite index of LPS-stimulated cytokines. The ratio of LPS-binding protein to soluble CD14 receptor (LBP:sCD14) was quantified as an index of endotoxemia that captures the relative reliance on pro-inflammatory versus non-inflammatory pathways for bacterial clearance. Levels of endotoxemia markers in blood were found to moderate gender differences in the link between depressive symptoms and stimulated inflammation (Gender × Depressive Symptoms × Endotoxemia: B = −0.039, 95%CI [-0.068, 0.009], p = 0.010). At lower LBP:sCD14 levels, depressive symptoms and stimulated inflammation were unrelated in both men and women. However, with higher levels of LBP:sCD14, men showed an increasingly positive correlation and women showed a negative correlation between depressive symptoms and stimulated inflammation. Hence, men and women exhibited similar associations between depressive symptoms and inflammatory responses at lower endotoxin marker levels, but these associations became divergent at higher levels of endotoxin markers. This information provides a novel perspective on risk factors for depression-linked alterations in inflammation, which may help to determine susceptibility to the downstream physical consequences of depressive symptomatology.

•

Depressive symptoms link to higher inflammation in men, lower inflammation in women.

•

These gender differences were only apparent at moderate or higher endotoxemia.

•

Men’s inflammation may be particularly sensitive to depressed mood and endotoxemia.

•

Endotoxemia may be an important factor in gender, depression and inflammation links.

HOTAIR regulates lipopolysaccharide-induced inflammatory response in hepatocytes

It has been widely accepted that long-noncoding RNA (lncRNA) HOX transcript antisense intergenic RNA (HOTAIR) emerges as a crucial mediator in inflammation. Here, we first detected HOTAIR in lipopolysaccharide (LPS)-treated normal human liver cell line (L02) and hepatocellular carcinoma cell lines (C3A, HepG2, and SMMC-7721). Further, we explored the biological function of HOTAIR in LPS-induced hepatocytes (L02 and C3A) lesions and investigated the molecular mechanisms. Besides, we focused on inflammatory signaling crosstalk. The inflammatory insults were assayed by cell counting kit-8 (CCK-8), cell cycle and apoptosis analysis kit, and immunoblotting assay. HOTAIR level was examined by reverse-transcription polymerase chain reaction. To determine the effect of HOTAIR silence or overexpression in inflammation, we applied quantitative reverse-transcription polymerase chain reaction, immunoblotting assay, and enzyme-linked immuno sorbent assay. Regulator inhibitors of Janus kinase/signal transducer and activator of transcription (JAK2/STAT3; AG490) and nuclear factor κB (NF-κB; BAY-11-7082) were applied to treat cells. Our results suggested that LPS induced the overexpression of HOTAIR in L02, C3A, HepG2, and SMMC-7721 cells. LPS repressed viability, induced apoptosis, and facilitated the expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in L02 and C3A cells. IL-1β, IL-6, and TNF-α were upregulated by HOTAIR overexpression while downregulated by HOTAIR knockdown in LPS-treated cells. We further observed that HOTAIR overexpression accelerated LPS-induced phosphorylation whereas HOTAIR silence blocked this progress. Inhibition of JAK/STAT and NF-κB contributed to the suppression of cytokines which was evoked by LPS. Collectively, our findings indicated that HOTAIR exerted a crucial role in cytokines expression by activating JAK/STAT and NF-κB.

Metabolic Endotoxemia: A Potential Underlying Mechanism of the Relationship between Dietary Fat Intake and Risk for Cognitive Impairments in Humans?

(1) Background: Nutrition is a major lifestyle factor that can prevent the risk of cognitive impairment and dementia. Diet-induced metabolic endotoxemia has been proposed as a major root cause of inflammation and these pathways emerge as detrimental factors of healthy ageing. The aim of this paper was to update research focusing on the relationship between a fat-rich diet and endotoxemia, and to discuss the potential role of endotoxemia in cognitive performances. (2) Methods: We conducted a non-systematic literature review based on the PubMed database related to fat-rich meals, metabolic endotoxemia and cognitive disorders including dementia in humans. A total of 40 articles out of 942 in the first screening met the inclusion criteria. (3) Results: Evidence suggested that a fat-rich diet, depending on its quality, quantity and concomitant healthy food components, could influence metabolic endotoxemia. Since only heterogeneous cross-sectional studies are available, it remains unclear to what extent endotoxemia could be associated or not with cognitive disorders and dementia. (4) Conclusions: A fat-rich diet has the capability to provide significant increases in circulating endotoxins, which highlights nutritional strategies as a promising area for future research on inflammatory-associated diseases. The role of endotoxemia in cognitive disorders and dementia remains unclear and deserves further investigation.

Gut Microbiota-Derived Components and Metabolites in the Progression of Non-Alcoholic Fatty Liver Disease (NAFLD)

Human gut microbiota has been increasingly recognized as a pivotal determinant of non-alcoholic fatty liver disease (NAFLD). Apart from the changes in the composition of gut microbiota, the components and metabolites derived from intestinal microbiota have emerged as key factors in modulating the pathological process of NAFLD. Compelling evidences have revealed that gut microbiota generates a variety of bioactive substances that interact with the host liver cells through the portal vein. These substances include the components derived from bacteria such as lipopolysaccharides, peptidoglycan, DNA, and extracellular vesicles, as well as the metabolites ranging from short-chain fatty acids, indole and its derivatives, trimethylamine, secondary bile acids, to carotenoids and phenolic compounds. The mechanisms underlying the hepatic responses to the bioactive substances from gut bacteria have been associated with the regulation of glycolipid metabolism, immune signaling response, and redox homeostasis. Illuminating the interplay between the unique factors produced from gut microbiome and the liver will provide a novel therapeutical target for NAFLD. The current review highlights the recent advances on the mechanisms by which the key ingredients and metabolites from gut microbiota modulate the development and progression of NAFLD.

Marital distress, depression, and a leaky gut: Translocation of bacterial endotoxin as a pathway to inflammation

BACKGROUND

Marital distress and depression work in tandem to escalate risks for inflammation-related disorders. Translocation of bacterial endotoxin (lipopolysaccharide, LPS) from the gut microbiota to blood circulation stimulates systemic inflammatory responses.

METHODS

To investigate increased gut permeability (a "leaky gut") as one potential mechanistic pathway from marital distress and depression to heightened inflammation, this secondary analysis of a double-blind, randomized crossover study examined serial assessments of two endotoxin biomarkers, LPS-binding protein (LBP) and soluble CD14 (sCD14), as well as C-reactive protein (CRP), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-α) during two separate 9.5 h visits. The 43 (N = 86) healthy married couples, ages 24-61 (mean = 38.22), discussed a marital disagreement during both visits; behavioral coding of these interactions provided data on hostile marital behaviors, a hallmark of marital distress. The Structured Diagnostic Interview for DSM-IV assessed participants' mood disorder history.

RESULTS

Participants with more hostile marital interactions had higher LBP than those who were less hostile. Additionally, the combination of more hostile marital interactions with a mood disorder history was associated with higher LBP/sCD14 ratios. Higher LBP and LBP/sCD14 were associated with greater CRP production; for example, only 21% of low LBP participants (lowest quartile) had average CRP across the day > 3, compared to 79% of those in the highest quartile. Higher sCD14 was associated with higher IL-6.

CONCLUSIONS

These bacterial LPS translocation data illustrate how a distressed marriage and a mood disorder history can promote a proinflammatory milieu through increased gut permeability, thus fueling inflammation-related disorders.

Blood concentrations of lipopolysaccharide-binding protein, high-sensitivity C-reactive protein, tumor necrosis factor-α, and Interleukin-6 in relation to insulin resistance in young adolescents

BACKGROUND

We assessed the association of insulin resistance as indicated by the homeostatic model assessment of insulin resistance (HOMA-IR) with inflammatory molecules, lipopolysaccharide-binding protein (LBP), high sensitivity C-reactive protein (hs-CRP), Tumor necrosis factor-α (TNF-α), and Interleukin-6 (IL-6) in urban young adolescents.

METHODS

Seventy-six adolescents (36 subjects with HOMA-IR ≥ 2.6 and 40 subjects with HOMA-IR < 2.6) were included in the study. We assessed anthropometric and laboratory measures, such as BMI, blood pressure, insulin sensitivity, liver enzymes, and lipid profiles along with the aforementioned inflammatory biomarkers. The diagnostic accuracy of LBP, hs-CRP, TNF-α, and IL-6 for insulin resistance was evaluated by using the receiver operating characteristic (ROC) curve analysis.

RESULTS

The mean age of the study subjects was 12.0 [12.0-13.0] y. Circulating LBP plasma concentration and hs-CRP were significantly increased in subjects with HOMA-IR ≥ 2.6 when compared with those with HOMA-IR < 2.6 (P < .0001). There was no difference in TNF-α or IL-6 concentrations between groups. Comparisons based on the area under the ROC curve for LBP, hs-CRP, TNF-α, and IL-6 with regard to insulin resistance (HOMA-IR ≥ 2.6) were 0.8384 (95% CI: 0.7380 to 0.9388), 0.7907 (95% CI: 0.6701 to 0.9113), 0.6207 (95% CI: 0.4770 to 0.7643), and 0.5763 (95% CI: 0.4285 to 0.7241), respectively.

CONCLUSIONS

Among LBP, hs-CRP, TNF-α, and IL-6, plasma LBP has the greatest diagnostic accuracy for insulin resistance in young adolescents. Prospective studies are warranted to delineate the value of LBP in the prediction of insulin resistance.

Reduced diversity and altered composition of the gut microbiome in individuals with myalgic encephalomyelitis/chronic fatigue syndrome

BACKGROUND

Gastrointestinal disturbances are among symptoms commonly reported by individuals diagnosed with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). However, whether ME/CFS is associated with an altered microbiome has remained uncertain. Here, we profiled gut microbial diversity by sequencing 16S ribosomal ribonucleic acid (rRNA) genes from stool as well as inflammatory markers from serum for cases (n = 48) and controls (n = 39). We also examined a set of inflammatory markers in blood: C-reactive protein (CRP), intestinal fatty acid-binding protein (I-FABP), lipopolysaccharide (LPS), LPS-binding protein (LBP), and soluble CD14 (sCD14).

RESULTS

We observed elevated levels of some blood markers for microbial translocation in ME/CFS patients; levels of LPS, LBP, and sCD14 were elevated in ME/CFS subjects. Levels of LBP correlated with LPS and sCD14 and LPS levels correlated with sCD14. Through deep sequencing of bacterial rRNA markers, we identified differences between the gut microbiomes of healthy individuals and patients with ME/CFS. We observed that bacterial diversity was decreased in the ME/CFS specimens compared to controls, in particular, a reduction in the relative abundance and diversity of members belonging to the Firmicutes phylum. In the patient cohort, we find less diversity as well as increases in specific species often reported to be pro-inflammatory species and reduction in species frequently described as anti-inflammatory. Using a machine learning approach trained on the data obtained from 16S rRNA and inflammatory markers, individuals were classified correctly as ME/CFS with a cross-validation accuracy of 82.93 %.

CONCLUSIONS

Our results indicate dysbiosis of the gut microbiota in this disease and further suggest an increased incidence of microbial translocation, which may play a role in inflammatory symptoms in ME/CFS.

Lipopolysaccharide-binding protein plasma levels as a biomarker of obesity-related insulin resistance in adolescents

Purpose

Lipopolysaccharide-binding protein (LBP) is a 65-kDa acute phase protein, derived from the liver, which is present in high concentrations in plasma. Data regarding the association between circulating plasma LBP levels and obesity-related biomarkers in the pediatric population are scarce. We aimed to determine whether there was a difference in plasma LBP levels between overweight/obese and normal-weight adolescents and to assess the correlation of circulating LBP levels with anthropometric measures and obesity-related biomarkers, including insulin resistance, liver enzyme levels, and lipid profiles.

Methods

The study included 87 adolescents aged 12–13 years; 44 were overweight/obese and 43 were of normal-weight. We assessed anthropometric and laboratory measures, including body mass index (BMI), blood pressure, insulin resistance, liver enzyme levels, and lipid profiles. Plasma LBP levels were measured using an enzyme-linked immunosorbent assay.

Results

The mean age of the participants was 12.9±0.3 years. Circulating plasma LBP levels were significantly increased in overweight/obese participants compared with those in normal-weight participants (7.8±1.9 µg/mL vs. 6.0±1.6 µg/mL, P<0.001). LBP levels were significantly and positively associated with BMI, systolic blood pressure, aspartate aminotransferase, alanine aminotransferase, total cholesterol, low density lipoprotein-cholesterol, fasting glucose and insulin, and insulin resistance as indicated by the homeostatic model assessment of insulin resistance (HOMA-IR) (all P<0.05). In multivariate linear regression analysis, BMI and HOMA-IR were independently and positively associated with plasma LBP levels.

Conclusion

LBP is an inflammatory biomarker associated with BMI and obesity-related insulin resistance in adolescents. The positive correlation between these parameters suggests a potentially relevant pathophysiological mechanism linking LBP to obesity-related insulin resistance in adolescents.

Structural and functional features of a developmentally regulated lipopolysaccharide-binding protein

Mammalian lipopolysaccharide (LPS) binding proteins (LBPs) occur mainly in extracellular fluids and promote LPS delivery to specific host cell receptors. The function of LBPs has been studied principally in the context of host defense; the possible role of LBPs in nonpathogenic host-microbe interactions has not been well characterized. Using the Euprymna scolopes-Vibrio fischeri model, we analyzed the structure and function of an LBP family protein, E. scolopes LBP1 (EsLBP1), and provide evidence for its role in triggering a symbiont-induced host developmental program. Previous studies showed that, during initial host colonization, the LPS of V. fischeri synergizes with peptidoglycan (PGN) monomer to induce morphogenesis of epithelial tissues of the host animal. Computationally modeled EsLBP1 shares some but not all structural features of mammalian LBPs that are thought important for LPS binding. Similar to human LBP, recombinant EsLBP1 expressed in insect cells bound V. fischeri LPS and Neisseria meningitidis lipooligosaccharide (LOS) with nanomolar or greater affinity but bound Francisella tularensis LPS only weakly and did not bind PGN monomer. Unlike human LBP, EsLBP1 did not bind N. meningitidis LOS:CD14 complexes. The eslbp1 transcript was upregulated ~22-fold by V. fischeri at 24 h postinoculation. Surprisingly, this upregulation was not induced by exposure to LPS but, rather, to the PGN monomer alone. Hybridization chain reaction-fluorescent in situ hybridization (HCR-FISH) and immunocytochemistry (ICC) localized eslbp1 transcript and protein in crypt epithelia, where V. fischeri induces morphogenesis. The data presented here provide a window into the evolution of LBPs and the scope of their roles in animal symbioses.

Mammalian lipopolysaccharide (LPS)-binding protein (LBP) is implicated in conveying LPS to host cells and potentiating its signaling activity. In certain disease states, such as obesity, the overproduction of this protein has been a reliable biomarker of chronic inflammation. Here, we describe a symbiosis-induced invertebrate LBP whose tertiary structure and LPS-binding characteristics are similar to those of mammalian LBPs; however, the primary structure of this distantly related squid protein (EsLBP1) differs in key residues previously believed to be essential for LPS binding, suggesting that an alternative strategy exists. Surprisingly, symbiotic expression of eslbp1 is induced by peptidoglycan derivatives, not LPS, a pattern converse to that of RegIIIγ, an important mammalian immunity protein that binds peptidoglycan but whose gene expression is induced by LPS. Finally, EsLBP1 occurs along the apical surfaces of all the host’s epithelia, suggesting that it was recruited from a general defensive role to one that mediates specific interactions with its symbiont.

Conventional, molecular methods and biomarkers molecules in detection of septicemia

Sepsis is a leading cause of morbidity and mortality in hospitalized patients worldwide and based on studies, 30–40% of all cases of severe sepsis and septic shock results from the blood stream infections (BSIs). Identifying of the disease, performing laboratory tests, and consequently treatment are factors that required for optimum management of BSIs. In addition, applying precise and immediate identification of the etiologic agent is a prerequisite for specific antibiotic therapy of pathogen and thereby decreasing mortality rates. The diagnosis of sepsis is difficult because clinical signs of sepsis often overlap with other noninfectious cases of systemic inflammation. BSIs are usually diagnosed by performing a series of techniques such as blood cultures, polymerase chain reaction-based methods, and biomarkers of sepsis. Extremely time-consuming even to take up to several days is a major limitation of conventional methods. In addition, yielding false-negative results due to fastidious and slow-growing microorganisms and also in case of antibiotic pretreated samples are other limitations. In comparison, molecular methods are capable of examining a blood sample obtained from suspicious patient with BSI and gave the all required information to prescribing antimicrobial therapy for detected bacterial or fungal infections immediately. Because of an emergency of sepsis, new methods are being developed. In this review, we discussed about the most important sepsis diagnostic methods and numbered the advantage and disadvantage of the methods in detail.

The synergistic effect of homocysteine and lipopolysaccharide on the differentiation and conversion of raw264.7 macrophages

BACKGROUND

Macrophages play pivotal roles in the progression of atherosclerosis (AS) and their heterogeneous differentiation patterns have been studied extensively. The classical subtype of activated macrophage, M1, promotes the progression of AS. Conversely, the alternative subtype of activated macrophage, M2, is regarded as a repressor of AS. Homocysteine (Hcy) may influence macrophage subtype polarization both in vivo and in vitro. Homocysteinemia (HHcy) is an independent risk factor in coronary heart disease and the effect of Hcy on macrophage differentiation has not been studied until now.

METHODS

Different concentrations of Hcy in combination with a fixed concentration of lipopolysaccharide (LPS, 200 ng/mL) were used to treat RAW264.7 macrophages. Real-time PCR was used to detect and quantify RNA transcripts indicative of M1 and M2 differentiation. The efficacy and specificity for each chemical stimulant in inducing macrophage differentiation were also investigated. The M2 macrophages (anti-inflammatory subtype) induced using classical methods (IL-4, 10 ng/mL) were also treated with different concentrations of Hcy complemented with LPS. The synergistic effect of Hcy and LPS in the converting the M2 subtype to M1 was also studied.

RESULTS

Macrophages can be induced to differentiate towards M1 by a combination of Hcy with LPS, with the strongest effect observed at an Hcy concentration of 50 μmol/L. After inducing macrophages to the M2 subtype using IL-4, treatment with both Hcy and LPS could elicit conversion from the M2 to M1 subtype.

CONCLUSION

Combined treatment with Hcy and LPS can induce the polarization of cultured RAW264.7 macrophages into the pro-inflammatory subtype, as well as promote subtype conversion from anti-inflammatory to pro-inflammatory.

Lipopolysaccharide-binding protein plasma levels in children: effects of obstructive sleep apnea and obesity

BACKGROUND

Obstructive sleep apnea (OSA) has been linked to obesity, inflammation, and metabolic syndrome. The gut microbiota, which serves as reservoir for bacterial lipopolysaccharides (LPS), could be altered by OSA and trigger inflammation. LPS-binding protein (LBP) serves as a surrogate marker of underlying low-grade endotoxemia by LPS from the gut. We hypothesized that systemic LBP levels would be higher in obese children and in those with OSA.

METHODS

Consecutive snoring and nonsnoring children (mean age 6.8 ± 1.3 y) were included after overnight polysomnography, and fasting levels of lipids, insulin glucose, and high-sensitivity C-reactive protein were obtained. Children were subdivided into four subgroups based on the presence of obesity or OSA. Plasma LBP levels were assayed using ELISA.

RESULTS

Of 219 participants, nonobese controls had the lowest levels of LBP, and the presence of obesity without OSA was associated with significant LBP increases. Nonobese children with OSA exhibited increased LBP levels, with obese children with OSA demonstrating the highest LBP levels of all four groups. Furthermore, LBP was independently associated with body mass index and with measures of OSA severity as well as with metabolic dysfunction, particularly insulin resistance as indicated by the homeostasis model assessment of insulin resistance.

CONCLUSIONS

Systemic low-level endotoxemia and resultant systemic inflammation is present in children who are either obese or suffer from OSA and is particularly prominent when both conditions are present. We postulate that disrupted sleep and other factors facilitating obesity such as a high-fat diet may disrupt the gut microbiome and lead to increased systemic LPS levels with resultant inflammation, promoting downstream metabolic dysfunction.

Inhibitory effect of Coptis chinensis on inflammation in LPS-induced endotoxemia

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizoma coptidis (RC) has been used as a remedy for inflammation-related diseases in traditional medicine. Although it is known to have anti-inflammatory activities, its mechanism of action on lipopolysaccharide (LPS)-induced inflammation has not yet been identified in detail.

AIM OF THE STUDY

This study was designed to assess the beneficial effects of pretreatment with RC in ameliorating LPS-induced liver inflammation.

MATERIALS AND METHODS

Mice were orally administered RC (500, 1000 mg/kg) for three days in a row. 1h after the last RC administration, the mice were intraperitoneally injected with LPS (35 mg/kg). After treatment, histological alterations and inflammatory factor levels in the liver and proinflammatory cytokines in the serum associated with inflammation were examined.

RESULTS

We found that pretreatment with RC (500 and 1000 mg/kg) exerted a significant protective effect by attenuating liver histopathological changes in endotoxemic mice. The results also demonstrated that RC suppressed secretion of LPS-stimulated pro-inflammatory cytokines, such as interleukin-6 (IL-6). Furthermore, RC inhibited LPS-mediated nuclear factor (NF)-κB activation via the prevention of IκB-α phosphorylation, as well as the phosphorylation of ERK1/2, JNK, and p38 MAPKs. These results were associated with decreases in the expression of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (I-NOS).

CONCLUSIONS

The results presented here clearly demonstrate that RC could significantly protect mice against LPS-induced acute liver injury.

Augmenter of liver regeneration (ALR) is a novel biomarker of hepatocellular stress/inflammation: in vitro, in vivo and in silico studies

The liver is a central organ involved in inflammatory processes, including the elaboration of acute-phase proteins. Augmenter of liver regeneration (ALR) protein, expressed and secreted by hepatocytes, promotes liver regeneration and maintains viability of hepatocytes. ALR also stimulates secretion of inflammatory cytokines (tumor necrosis factor [TNF]-α and interleukin [IL]-6) and nitric oxide from Kupffer cells. We hypothesized that ALR may be involved in modulating inflammation induced by various stimuli. We found that hepatic ALR levels are elevated at 24 h, before or about the same time as an increase in the mRNA expression of TNF-α and IL-6, after portacaval shunt surgery in rats. Serum ALR also increased, but significantly only on d 4 when pathological changes in the liver become apparent. In rats, serum ALR was elevated after intraperitoneal administration of lipopolysaccharide alone and in a model of gram-negative sepsis. Serum ALR increased before alanine aminotransferase (ALT) in endotoxemia and in the same general time frame as TNF-α and IL-6 in the bacterial sepsis model. Furthermore, mathematical prediction of tissue damage correlated strongly with alterations in serum ALR in a mouse model of hemorrhagic shock. In vitro, monomethyl sulfonate, TNF-α, actinomycin D and lipopolysaccharide all caused increased release of ALR from rat hepatocytes, which preceded the loss of cell viability and/or inhibition of DNA synthesis. ALR may thus serve as a potential diagnostic marker of hepatocellular stress and/or acute inflammatory conditions.

Lipopolysaccharide-binding protein, a surrogate marker of microbial translocation, is associated with physical function in healthy older adults

BACKGROUND

Physical function declines, and markers of inflammation increase with advancing age, even in healthy persons. Microbial translocation (MT) is the systemic exposure to mucosal surface microbes/microbial products without overt bacteremia and has been described in a number of pathologic conditions. We hypothesized that markers of MT, soluble CD14 (sCD14) and lipopolysaccharide (LPS) binding protein (LBP), may be a source of chronic inflammation in older persons and be associated with poorer physical function.

METHODS

We assessed cross-sectional relationships among two plasma biomarkers of MT (sCD14 and LBP), physical function (hand grip strength, short physical performance battery [SPPB], gait speed, walking distance, and disability questionnaire), and biomarkers of inflammation (C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), TNF-α soluble receptor 1 [TNFsR1]) in 59 older (60-89 years), healthy (no evidence of acute or chronic illness) men and women.

RESULTS

LBP was inversely correlated with SPPB score and grip strength (p = .02 and p < .01, respectively) and positively correlated with CRP (p = 0.04) after adjusting for age, gender, and body mass index. sCD14 correlated with IL-6 (p = .01), TNF-α (p = .05), and TNFsR1 (p < .0001). Furthermore, the correlations between LBP and SPPB and grip strength remained significant after adjusting for each inflammatory biomarker.

CONCLUSIONS

In healthy older individuals, LBP, a surrogate marker of MT, is associated with worse physical function and inflammation. Additional study is needed to determine whether MT is a marker for or a cause of inflammation and the associated functional impairments.

Lipopolysaccharide binding protein is down-regulated during acute liver failure

BACKGROUND AND AIMS

Lipopolysaccharide binding protein (LBP) is involved in the modulation of acute liver injury and failure caused by acetaminophen (APAP). Although the biological activity of LBP is concentration dependent, little is known about its levels in acute liver failure.

METHODS

Serum and hepatic LBP were measured in acute APAP-induced liver injury in mice. Serum LBP was measured in patients with acute liver failure from APAP and non-APAP causes.

RESULTS

Interestingly, contrary to other diseases, serum and hepatic LBP levels decreased significantly in mice within 24 h after being subjected to APAP-induced injury compared to the control (1.6 ± 0.1 vs. 3.5 ± 1.6 μg/ml, respectively; P < 0.05). Similar decreases were noted in another mouse model of acute liver injury due to carbon tetrachloride. Among patients with acute liver failure due to APAP (n = 5) and non-APAP (n = 5) causes, admission LBP levels were decreased compared to those of healthy controls (5.4 ± 1.4 vs. 3.2 ± 0.2 μg/ml, normal vs. acute liver failure; P = 0.07). However, the levels were not associated with the etiology of acute liver failure or 3-week outcome.

CONCLUSIONS

Serum and hepatic LBP levels are significantly reduced early after the induction of severe acute liver injury/failure due to acetaminophen and other liver injuries. This reduction in LBP production is specific to acute liver failure and may be important in developing future diagnostic and therapeutic approaches for patients with acute liver failure.

Lipopolysaccharide binding protein inhibitory peptide protects against acetaminophen-induced hepatotoxicity

Acetaminophen (APAP)-induced liver injury remains the main cause of acute liver failure in the United States. Our previous work demonstrated that LPS binding protein (LBP) knockout mice are protected from APAP-induced hepatotoxicity. LBP is known to bind avidly to LPS, facilitating cellular activation. In this study, we sought to specifically inhibit the interaction between LBP and LPS to define the role of this interaction in APAP-induced liver injury. The peptide LBPK95A was able to inhibit LBP-mediated LPS activation of RAW 267.4 cells in a dose-dependent manner in vitro. In vivo, C57Bl/6 mice were treated with either LBPK95A or vehicle control concurrently with the administration of APAP (350 mg/kg). Mice treated with LBPK95A had significantly lower serum aspartate aminotransferase and alanine aminotransferase levels. Morphometric analysis of the liver tissue showed significantly less liver injury in mice treated with LBPK95A. To assess whether the LBPK95A altered glutathione depletion and APAP metabolism, we measured total glutathione levels in the liver after APAP. We found no difference in the glutathione levels and APAP-adduct formation between LBPK95A vs. vehicle control both at baseline and after APAP. In conclusion, our results support the hypothesis that LBP-induced liver injury after APAP is due to its ability to mediate activation by endogenous LPS. Our results suggest that blocking LBP-LPS interactions is a potential therapeutic avenue for the treatment of APAP-induced liver injury.

Alcoholic liver disease and the gut-liver axis

Alcoholic liver disease (ALD) is one of the leading causes of liver diseases and liver-related death worldwide. Of the many factors that contribute to the pathogenesis of ALD, gut-derived lipopolysaccharide (LPS) plays a central role in induction of steatosis, inflammation, and fibrosis in the liver. In this review, we discuss the mechanisms by which alcohol contributes to increased gut permeability, the activation of Kupffer cells, and the inflammatory cascade by LPS. The role of the Toll-like receptor 4 (TLR4) complex in LPS recognition and the importance of the TLR4-induced signaling pathways are evaluated in ALD.

The systemic and pulmonary LPS binding protein response to intratracheal lipopolysaccharide

LPS binding protein (LBP) is an acute-phase glycoprotein that facilitates LPS activation of immune cells through interactions with CD14 and Toll-like receptor 4. Initially, LBP production was thought to occur exclusively in the liver in response to stimulation with TNF-alpha, IL-1, and IL-6. More recently, it has been shown that type II pneumocytes are also capable of LBP production. Little is known, however, regarding the regulation and or distribution of this protein in response to localized intrapulmonary infection. We performed time-course experiments challenging C3H mice intratracheally with LPS (10 mug). In separate experiments, mice deficient in IL-6 were given the same dose of intratracheal LPS and euthanized 8 h later. Despite the intratracheal route of LPS administration, an increase in plasma LBP concentrations occurred earlier and was of greater magnitude than the increase observed in bronchoalveolar lavage fluid. Liver LBP mRNA increased to a greater extent than did lung LBP mRNA. Whereas the TNF-alpha response remained localized within the alveolar space, IL-6 was increased both locally and in plasma. Of several tissues analyzed, the lung was the greatest producer of IL-6 mRNA. Plasma LBP was significantly decreased in the IL-6-deficient mice compared with wild-type controls challenged with intratracheal LPS. We conclude that lung-derived IL-6 is an important mediator of hepatic LBP up-regulation. We speculate that the disruption of these lung-liver signaling pathways may be important to host response efforts to confine infection to the lung. If impaired, this may be one mechanism underlying the increased mortality observed in patients with liver disease who develop pneumonia.

Upregulation of TNF-alpha and IL-6 mRNA in mouse liver induced by bacille Calmette-Guerin plus lipopolysaccharide

AIM

To investigate the mechanism of immunological liver injury induced by bacille Calmette-Guerin (BCG) plus lipopolysaccharide (LPS).

METHODS

Mice were injected via the tail vein with 125 mg/kg BCG, and 12 d later, the mice were injected intravenously with different doses of LPS (125, 250, or 375 microg/kg). Serum alanine aminotransferase (ALT) activity and liver pathological changes were examined. The expression of tumor necrosis factor (TNF)- alpha, interleukin (IL)-6, lipopolysaccharide binding protein (LBP) and CD14 mRNA, and NF-kappaB and IkappaB-alpha protein in mouse liver at different time points after BCG and LPS injection were measured using RT-PCR, immunohistochemistry and Western blotting analysis, respectively.

RESULTS

The activity of serum ALT in mice treated with BCG and LPS was significantly increased. Different degrees of liver injury, such as inflammatory cell infiltration, spotty necrosis, piecemeal necrosis, even bridging necrosis, could be seen in liver sections from mice after BCG and LPS administration. Furthermore, the levels of TNF-alpha and IL-6 mRNA in mouse liver were significantly elevated after administration of BCG plus LPS (P<0.05). The levels of LBP and CD14 mRNA in mouse liver were markedly upregulated after treatment with BCG and LPS, and treatment with BCG alone led to an increase in CD14 mRNA in mouse liver. Finally, immunoreactivity for NF-kappaB p65 was predominantly detected in hepatocyte nuclei from mice treated with BCG plus LPS, compared with the normal group. Protein levels of IkappaB-alpha were strikingly decreased by LPS or BCG plus LPS treatment, compared with the normal group or BCG group.

CONCLUSION

TNF-alpha and IL-6 mRNA were partially involved in early immunological liver injury induced by challenge with small doses of LPS after BCG priming. Upregulation of TNF-alpha and IL-6 mRNA might be related to increases in LBP and CD14 mRNA expression and activation of NF-kappaB. Furthermore, BCG priming in immunological liver injury may occur via upregulation of CD14 mRNA expression in mononuclear cell infiltration into the liver.

XIAP Is a Copper Binding Protein Deregulated in Wilson's Disease and Other Copper Toxicosis Disorders

X-linked inhibitor of apoptosis (XIAP), known primarily for its caspase inhibitory properties, has recently been shown to interact with and regulate the levels of COMMD1, a protein associated with a form of canine copper toxicosis. Here, we describe a role for XIAP in copper metabolism. We find that XIAP levels are greatly reduced by intracellular copper accumulation in Wilson's disease and other copper toxicosis disorders and in cells cultured under high copper conditions. Elevated copper levels result in a profound, reversible conformational change in XIAP due to the direct binding of copper to XIAP, which accelerates its degradation and significantly decreases its ability to inhibit caspase-3. This results in a lowering of the apoptotic threshold, sensitizing the cell to apoptosis. These data provide an unsuspected link between copper homeostasis and the regulation of cell death through XIAP and may contribute to the pathophysiology of copper toxicosis disorders.

Binding of LPS and LPS--LDL complexes to rat hepatocytes

We studied binding of 3H-LPS toxin and LPS complexes with serum 125I-LDL to primary culture of rat hepatocytes. Receptor binding of LPS and LDL--LPS complex was 50 and 77% of the total, respectively. Scatchard plot was linear in both cases. LDL and LDL--LPS complexes were inessential for LPS binding, while LDL--LPS binding was appreciably suppressed by LPS (-30%) and LDL (-65%).

Induction of IL-6 within the rodent intestinal muscularis after intestinal surgical stress

BACKGROUND

Postoperative ileus is a poorly understood surgical problem characterized by leukocyte extravasation into the intestinal muscularis and suppression in muscle function. The study objective was to delineate a mechanistic inflammatory cascade initiated by intestinal manipulation.

METHODS

ACI and Sprague-Dawley rats, and IL-6 +/+ and IL-6 -/- mice were subjected to intestinal manipulation. One group of rats received adhesion molecule-blocking antibodies (1A29 and WT.3) before intestinal manipulation. Interleukin-6 (IL-6) messenger RNA (mRNA) levels and electrophoretic mobility shift assay for signal transducers and activators of transcription (STAT) activation were measured in tissue extracts. IL-6 protein levels were assessed by immunohistochemistry and enzyme-linked immunosorbent assay.

RESULTS

IL-6 mRNA from muscularis extracts demonstrated a significant induction after intestinal manipulation. No IL-6 induction was observed in mucosal extracts. Adhesion molecule blockade resulted in a marked decrease of cellular infiltration but did not change IL-6 mRNA expression in muscularis extracts. Resident macrophages in the muscularis stained for IL-6 by immunohistochemistry after intestinal manipulation. The isolated manipulated muscularis demonstrated a significant increase in IL-6 release. Electrophoretic mobility shift assay of manipulated muscularis showed a marked increase in IL-6-dependent Stat3 activation.

CONCLUSIONS

This study demonstrates that manipulation of the small bowel during an abdominal operation initiates downstream induction, translation, release, and functional activity of IL-6 within the muscularis.

Receptors, mediators, and mechanisms involved in bacterial sepsis and septic shock

Bacterial sepsis and septic shock result from the overproduction of inflammatory mediators as a consequence of the interaction of the immune system with bacteria and bacterial wall constituents in the body. Bacterial cell wall constituents such as lipopolysaccharide, peptidoglycans, and lipoteichoic acid are particularly responsible for the deleterious effects of bacteria. These constituents interact in the body with a large number of proteins and receptors, and this interaction determines the eventual inflammatory effect of the compounds. Within the circulation bacterial constituents interact with proteins such as plasma lipoproteins and lipopolysaccharide binding protein. The interaction of the bacterial constituents with receptors on the surface of mononuclear cells is mainly responsible for the induction of proinflammatory mediators by the bacterial constituents. The role of individual receptors such as the toll-like receptors and CD14 in the induction of proinflammatory cytokines and adhesion molecules is discussed in detail. In addition, the roles of a number of other receptors that bind bacterial compounds such as scavenger receptors and their modulating role in inflammation are described. Finally, the therapies for the treatment of bacterial sepsis and septic shock are discussed in relation to the action of the aforementioned receptors and proteins.

Intra-abdominal activation of a local inflammatory response within the human muscularis externa during laparotomy

OBJECTIVE

To investigate the initiation of a complex inflammatory response within the human intestinal muscularis intraoperatively so as to determine the clinical applicability of the inflammatory hypothesis of postoperative ileus.

SUMMARY BACKGROUND DATA

Mild intestinal manipulation in rodents initiates the activation of transcription factors, upregulates proinflammatory cytokines, and increases the release of kinetically active mediators (nitric oxide and prostaglandins), all of which results in the recruitment of leukocytes and a suppression in motility (i.e., postoperative ileus).

METHODS

Human small bowel specimens were harvested during abdominal procedures at various times after laparotomy. Histochemical and immunohistochemical techniques were applied to intestinal muscularis whole-mounts. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed for interleukin (IL)-6, IL-1beta, tumor necrosis factor (TNF)-alpha, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). Signal transducers and activators of transcription (STAT) protein phosphorylation was determined by electromobility shift assay. Organ bath experiments were performed on jejunal circular smooth muscle strips. GW274150C and DFU were used in vitro as iNOS and COX-2 inhibitors.

RESULTS

Normal human muscularis externa contained numerous macrophages that expressed increased lymphocyte function associated antigen-1 (LFA-1) immunoreactivity as a function of intraoperative time. RT-PCR demonstrated a time-dependent induction of IL-6, IL-1beta, TNF-alpha, iNOS, and COX-2 mRNAs within muscularis extracts after incision. Mediators were localized to macrophages with STAT protein activation in protein extracts demonstrating local IL-6 functional activity. DFU alone or in combination with GW274150C increased circular muscle contractility. Specimens harvested after reoperation developed leukocytic infiltrates and displayed diminished in vitro muscle contractility.

CONCLUSIONS

These human data demonstrate that surgical trauma is followed by resident muscularis macrophage activation and the upregulation, release, and functional activity of proinflammatory cytokines and kinetically active mediators.

Innate and acquired immunity intersect in a global view of the acute-phase response

Recognition of stereotypic chemical patterns by sentinel cells of the innate immune system provokes a transient deviation from homeostasis, the acute-phase response (APR). Although APR effectors have been identified individually, the complexity of the response suggested that emergent properties would be uncovered by a more comprehensive examination. Our global assessment revealed that approximately 7% of genes in the mouse are mobilized in the hepatic APR to endotoxin. Extensive metabolic adjustments include suppression of pathways for cholesterol, fatty acid, and phospholipid synthesis. Increased expression of genes for innate defense was accompanied by coordinate induction of the MHC class I antigen presentation machinery, illustrating an intersection between innate and adaptive immunity.

Lipopolysaccharides in liver injury: molecular mechanisms of Kupffer cell activation

Endogenous gut-derived bacterial lipopolysaccharides have been implicated as important cofactors in the pathogenesis of liver injury. However, the molecular mechanisms by which lipopolysaccharides exert their effect are not entirely clear. Recent studies have pointed to proinflammatory cytokines such as tumor necrosis factor-alpha as mediators of hepatocyte injury. Within the liver, Kupffer cells are major sources of proinflammatory cytokines that are produced in response to lipopolysaccharides. This review will focus on three important molecular components of the pathway by which lipopolysaccharides activate Kupffer cells: CD14, Toll-like receptor 4, and lipopolysaccharide binding protein. Within the liver, lipopolysaccharides bind to lipopolysaccharide binding protein, which then facilitates its transfer to membrane CD14 on the surface of Kupffer cells. Signaling of lipopolysaccharide through CD14 is mediated by the downstream receptor Toll-like receptor 4 and results in activation of Kupffer cells. The role played by these molecules in liver injury will be examined.

Activation of the lipopolysaccharide signaling pathway in hepatic transplantation preservation injury

BACKGROUND

Endotoxin or lipopolysaccharide (LPS) initiates a cascade of complications of septic shock and multiple organ failure seen in Gram-negative bacterial infections. The first step of this pathway, which leads to activated nuclear factor (NF)-kappaB, activating protein (AP)-1, and other transcription factors, is the formation of the LPS receptor complex by LPS, LPS-binding protein (LBP), CD14, and toll-like receptor (TLR) 2 or 4. We examined whether the LPS signaling pathway is activated by hepatic ischemia/reperfusion injury in the transplant setting.

METHODS

Orthotopic syngeneic rat liver transplantation was performed with 0 to 18 hr of cold preservation in University of Wisconsin solution. Animals were killed 1 to 48 hr after reperfusion. Northern blot analysis for CD14, LBP, and TLR2 mRNA, immunohistochemistry for LBP, liver enzyme analysis, and gel shift assay for NF-kappaB and AP-1 were performed.

RESULTS

LPS levels were elevated early after reperfusion. Aspartate aminotransferase and alanine aminotransferase maximally increased 12 hr after transplantation. LBP mRNA and protein and CD14 mRNA were significantly up-regulated peaking at 6 to 12 hr after reperfusion. TLR2 mRNA was also increased. NF-kappaB activity showed a biphasic peak at 1 to 3 hr and 12 hr after reperfusion, whereas AP-1 activity showed a peak at 3 to 6 hr. The induction of CD14 mRNA correlated with the length of cold ischemia time.

CONCLUSIONS

These data indicate that multiple components of the LPS signaling pathway are activated during ischemia/reperfusion injury after liver transplantation.

Role of toll-like receptors in changes in gene expression and NF-kappa B activation in mouse hepatocytes stimulated with lipopolysaccharide

The liver is an important site of host-microbe interaction. Although hepatocytes have been reported to be responsive to lipopolysaccharide (LPS), the global gene expression changes by LPS and mechanism(s) by which LPS stimulates cultured hepatocytes remain uncertain. Cultures of primary mouse hepatocytes were incubated with LPS to assess its effects on the global gene expression, hepatic transcription factors, and mitogen-activated protein (MAP) kinase activation. DNA microarray analysis indicated that LPS modulates the selective expression of more than 80 genes and expressed sequence tags. We have shown previously that hepatocytes express CD14, which is required both for uptake and responsiveness to LPS. In other cells, responsiveness to microbial products requires expression of Toll-like receptors (TLR) and their associated accessory molecules. Hepatocytes expressed TLR1 through TLR9 as well as MyD88 and MD-2 transcripts, as shown by reverse transcriptase PCR analysis, indicating that hepatocytes express all known microbe recognition molecules. The MAP kinase extracellular signal-regulated kinase 1/2 was phosphorylated in response to LPS in mouse hepatocytes, and the levels of phosphorylation were lower in hepatocytes from TLR4-null mice. NF-kappa B activation was reduced in TLR4-mutant or -null hepatocytes compared to control hepatocytes, and this defect was partially restored by adenoviral transduction of mouse TLR4. Thus, hepatocytes respond to nanogram concentrations of LPS through a TLR4 response pathway.

The immunomodulatory action of dexamethasone on monoclonal antibody-producing hybridoma cells

As found in different studies, glucocorticoid hormones (GCs) as well as interleukin-6 (IL-6) are involved in the modulation of protein glycosylation. In this work we have investigated the immunomodulatory effect of dexamethasone by assessing in vitro IgG glycosylation by monoclonal antibody-producing hybridoma cells. As described in myeloma cell lines, cellular viability and proliferation rates of hybridoma 112D5 cells decrease when cultured with dexamethasone during 24 hours, in a dose-dependent way. Moreover, the corticosteroid triggered apoptosis of the hybridoma, which was observed as soon as 4 h after culturing cells in the presence of the drug. In line with these results, after 24 h, dexamethasone induced a drop in the anti-DNP level of antibodies synthesized by hybridoma 112D5. In previous works we described that asymmetric glycosylation of in vitro synthesized IgG correlated with induction of cell damage. Nevertheless, an increase in asymmetric IgG glycosylation was not observed here, but there was a decrease in the proportion of asymmetrically glycosylated IgG synthesized by the hybridoma after a 4-h culture with the drug. Finally, as results from assessing IL-6 production by ELISA, we conclude that the above described effects of dexamethasone on hybridoma 112D5 cells could not be due to the inhibition of IL-6 synthesis exerted by the corticoid but rather to a direct effect of the drug. Monoclonal antibody (MAb) producing hybridomas provide an excellent in vitro model for the study of the molecular mechanisms involved in immunoglobulin glycosylation.

Cloning and characterization of the homolog of mammalian lipopolysaccharide-binding protein and bactericidal permeability-increasing protein in rainbow trout Oncorhynchus mykiss

We cloned two cDNAs denoted as RT-LBP/BPI-1 and RT-LBP/BPI-2, respectively, which were derived from the mRNA of head kidney from rainbow trout. They showed structural homology with LPS-binding protein (LBP) and bactericidal/permeability-increasing protein (BPI) in mammals. The full-length cDNA of RT-LBP/BPI-1 and RT-LBP/BPI-2 is 1666 and 1741 bp, respectively. Both cDNAs encoded 473 aa residues, including the amino acids conserved in mammalian LBP and BPI proteins that were assumed to be involved in LPS binding. The overall coding sequence of RT-LBP/BPI-1 has 33% amino acid homology to human LBP and 34% to human BPI, and RT-LBP/BPI-2 has 32% amino acid homology to human LBP and 33% to human BPI. Three-dimensional structure analysis by three-dimensional/one-dimensional (3D-1D) methods also demonstrated that RT-LBP/BPI-1 and RT-LBP/BPI-2 proteins showed significant similarity to human BPI, having a boomerang shape with N-terminal and C-terminal barrels. Phylogenetic analysis showed that the LBP and BPI genes seemed to be established after the divergence of mammals from teleosts. These results suggested that RT-LBP/BPI-1 and RT-LBP/BPI-2 may be a putative ortholog for mammalian LBP and/or BPI genes. This is the first study to identify the LBP family genes from nonmammalian vertebrates.

MCP-1 causes leukocyte recruitment and subsequently endotoxemic ileus in rat

Endotoxemia causes an inflammatory response within the intestinal muscularis and gastrointestinal dysmotility. We hypothesize that the resident macrophage-derived chemokine monocyte chemoattractant protein-1 (MCP-1) plays a significant role in the recruitment of leukocytes into the lipopolysaccharide (LPS)-stimulated rat intestinal muscularis. MCP-1 mRNA expression was investigated by RT-PCR. Leukocyte extravasation and MCP-1 protein localization were determined by immunohistochemistry. Contractile activity was assessed by using a standard organ bath in rats that were treated with saline, recombinant MCP-1, LPS, LPS + nonspecific antibody, or LPS + MCP-1 antibody. Endotoxemia caused a significant 280-fold increase in MCP-1 mRNA expression in the muscularis, peaking at 3 h. MCP-1 protein was immunohistochemically located to muscularis macrophages. LPS application caused significant leukocyte recruitment into the muscularis and a 51% decrease in muscle contractility. MCP-1 antibody treatment significantly averted leukocyte recruitment and significantly prevented muscle dysfunction. These parameters were not significantly altered by the nonspecific antibody. Results show that resident muscularis macrophage-derived MCP-1 plays a major role in the recruitment of monocytes during endotoxemia, which then subsequently secrete kinetically active substances that cause ileus.

Up-regulated expression of HGF in rat liver cells after experimental endotoxemia: a potential pathway for enhancement of liver regeneration

A lipopolysaccharide (LPS)-induced inflammation prior to an hepatic resection has been shown to enhance liver regeneration in rat. The aim of the present study was to investigate the expression of hepatocyte growth factor (HGF) and its c-Met receptor under such experimental conditions. Animals were submitted to a two-third hepatectomy or a LPS challenge carried out 12 h prior to resection. Non parenchymal and parenchymal cells were isolated from livers obtained at various times post-hepatectomy. Quantitative RT-PCR for HGF and c-Met mRNAs were performed from total liver or purified cell fractions and HGF mRNA was also analyzed by in situ RT-PCR on liver sections. A LPS challenge alone induced a marked up-regulation of HGF mRNA level in whole liver and isolated hepatocytes. Furthermore, when partial hepatectomy (PH) was preceded by a LPS challenge, an increase of HGF mRNA level was seen in whole liver and contrasted with a decreased level in non parenchymal cells. These results were confirmed by in situ RT-PCR. In isolated hepatocytes from endotoxemic rats, the mRNA level for the LPS-specific membranous receptor mCD14 was markedly up-regulated and even more so when LPS was followed by PH. Moreover, a TNFalpha challenge alone induced an up-regulation of HGF mRNA in hepatocytes and a down-regulation in non parenchymal cells (NPCs). Overall, when a LPS challenge is given prior to PH the major source of hepatic HGF appears to be the hepatocyte itself rather than NPCs. An autocrine HGF/c-Met loop which promotes the proliferative potential of the hepatic parenchymal cell and participates in liver regeneration is postulated.

Kupffer cell inactivation alleviates ethanol-induced steatosis and CYP2E1 induction but not inflammatory responses in rat liver

BACKGROUND/AIMS

Gadolinium chloride inactivates Kupffer cells and alleviates alcohol-induced liver lesions. We investigated the mechanism of gadolinium chloride protection after oral ethanol feeding.

METHODS

Rats were maintained ethanol-intoxicated for 6 weeks by feeding ethanol in a low-carbohydrate/high-fat liquid diet. Macrophages were inactivated by intravenous administrations of gadolinium chloride. At termination, liver samples and cell lysates obtained from the periportal and perivenous region were analyzed for histopathology, mRNA expression of endotoxin-associated parameters and cytokines and for enzymes involved in oxidative stress.

RESULTS

Ethanol treatment alone caused marked microvesicular/macrovacuolar steatosis and focal inflammation. Gadolinium significantly alleviated pathology, by reducing steatosis but not inflammation. Gadolinium treatment eliminated ED2 immunopositive Kupffer cells, which were larger and more frequent periportally. Ethanol significantly increased the mRNA expression of the endotoxin (LPS) receptor CD14 and the LPS binding protein LBP, but not that of the pro-inflammatory cytokines TNF-alpha and IL-1beta. The mRNA of CD14 was found to be expressed preferentially in the perivenous region, but gadolinium treatment had no significant effect on the expression or the distribution. However, gadolinium significantly moderated the ethanol induction of CYP2E1 and this effect correlated to the degree of steatosis. Ethanol increased glutathione transferase and reduced glutathione peroxidase activity, but these changes persisted after gadolinium treatment.

CONCLUSIONS

Our results suggest that gadolinium chloride reduces symptoms of ALD mainly by counteracting steatosis, and that CD14-positive Kupffer cell populations are not involved in gadolinium protection. The strong correlation between pathology and CYP2E1 induction might suggest a steatopathogenic role for this enzyme.

Role of inducible nitric oxide synthase in postoperative intestinal smooth muscle dysfunction in rodents

BACKGROUND & AIMS

We have shown that intestinal manipulation leads to a significant inhibition of circular muscle contraction. We hypothesized that the inflammatory mediator inducible nitric oxide (NO) plays a role in surgically induced ileus.

METHODS

Rats and inducible NO synthase (iNOS) knockout and wild-type mice underwent a simple intestinal manipulation. Reverse-transcription polymerase chain reaction and immunohistochemistry were used to detect and localize iNOS expression. Nitrite and NO production were measured in muscularis cultures. Spontaneous and bethanechol-stimulated jejunal circular muscle contractions were measured in an organ bath.

RESULTS

Intestinal manipulation resulted in significant iNOS messenger RNA induction in mucosa and muscularis. Immunohistochemistry localized iNOS in phagocytes within the muscularis. Nitrite and NO production increased 59.8-fold 24 hours after manipulation. L-n(6)-(1-iminoethyl) lysine (L-NIL) inhibited this response. In control rats, selective iNOS inhibition did not increase spontaneous muscle activity, but after manipulation L-NIL significantly improved spontaneous activity. iNOS knockout mice showed a significant 81% decrease in neutrophil infiltration into the muscularis after intestinal manipulation compared with wild-types. Contractile activity was normal in knockout mice after intestinal manipulation.

CONCLUSIONS

These results show that leukocyte-derived inducible NO inhibits gastrointestinal motility after manipulation and plays an essential role in the initiation of intestinal inflammation.

Lipopolysaccharide Binding Protein and Serum Amyloid A Secretion by Human Intestinal Epithelial Cells During the Acute Phase Response

The acute phase proteins LPS binding protein (LBP) and serum amyloid A (SAA) are produced by the liver and are present in the circulation. Both proteins have been shown to participate in the immune response to endotoxins. The intestinal mucosa forms a large surface that is continuously exposed to these microbial products. By secretion of antimicrobial and immunomodulating agents, the intestinal epithelium contributes to the defense against bacteria and their products. The aim of this study was to explore the influence of the inflammatory mediators TNF-α, IL-6, and IL-1β on the release of LBP and SAA by intestinal epithelial cells (IEC). In addition, the induction of LBP and SAA release by cell lines of intestinal epithelial cells and hepatic cells was compared. The data obtained show that in addition to liver cells, IEC also expressed LBP mRNA and released bioactive LBP and SAA upon stimulation. Regulation of LBP and SAA release by IEC and hepatocytes was typical for class 1 acute phase proteins, although differences in regulation between the cell types were observed. Endotoxin did not induce LBP and SAA release. Glucocorticoids were demonstrated to strongly enhance the cytokine-induced release of LBP and SAA by IEC, corresponding to hepatocytes. The data from this study, which imply that human IEC can produce LBP and SAA, suggest a role for these proteins in the local defense mechanism of the gut to endotoxin. Furthermore, the results demonstrate that tissues other than the liver are involved in the acute phase response.