Determinants of serum concentrations of lipopolysaccharide-binding protein (LBP) in the adult population: the role of obesity

Links Between Adipose Tissue Gene Expression of Gut Leakage Markers, Circulating Levels, Anthropometrics, and Diet in Patients with Coronary Artery Disease

Background

Recent studies suggest gut-derived lipopolysaccharide (LPS)-translocation to play a role in both systemic inflammation and in inflammatory adipose tissue. We aimed to investigate whether circulating LPS-related inflammatory markers and corresponding genetic expression in adipose tissue were associated with obesity, cardiometabolic risk factors, and dietary habits in patients with coronary artery disease.

Methods

Patients (n=382) suffering a myocardial infarction 2-8 weeks prior to inclusion were enrolled in this cross-sectional study. Subcutaneous adipose tissue (SAT), taken from the gluteal region, and fasting blood samples were collected at inclusion for determination of genetic expression of LPS-binding protein (LBP), CD14, toll-like receptor 2 (TLR2), and TLR4 in SAT, and LPS, LBP, and soluble cluster of differentiation 14 (sCD14) in the circulation. All patients filled out a dietary registration form.

Results

Patients (median age 74 years, 25% women), had a median body mass index (BMI) of 25.9 kg/m2. Circulating levels of LBP correlated to BMI (p=0.02), were significantly higher in overweight or obese (BMI≥25 kg/m2) compared to normal- or underweight patients (BMI<25 kg/m2), and were significantly elevated in patients with T2DM, hypertension, and MetS, compared to patients without (p≤0.04, all). In SAT, gene expression of CD14 and LBP correlated significantly to BMI (p≤0.001, both), and CD14 and TLR2 expressions were significantly higher in patients with T2DM and MetS compared to patients without (p≤0.001, both). Circulating and genetically expressed CD14 associated with use of n-3 PUFAs (p=0.008 and p=0.003, respectively). No other significant associations were found between the measured markers and dietary habits.

Conclusion

In patients with established CAD, circulating levels of LBP and gene expression of CD14 and TLR2 in SAT were related to obesity, MetS, T2DM, and hypertension. This suggests that the LPS-LBP-CD14 inflammatory axis is activated in the chronic low-grade inflammation associated with cardiometabolic abnormalities, whereas no significant associations with dietary habits were observed.

Immunometabolic adaptation in monocytes underpins functional changes during pregnancy

Metabolic heterogeneity is a determinant of immune cell function. The normal physiological metabolic reprogramming of pregnancy that ensures the fuel requirements of mother and baby are met, might also underpin changes in immunity that occur with pregnancy and manifest as altered responses to pathogens and changes to autoimmune disease symptoms. Using peripheral blood from pregnant women at term, we reveal that monocytes lose M2-like and gain M1-like properties accompanied by reductions in mitochondrial mass, maximal respiration, and cardiolipin content in pregnancy; glycolysis is unperturbed. We establish that muramyl dipeptide (MDP)-stimulated cytokine production relies on oxidative metabolism, then show in pregnancy reduced cytokine production in response to MDP but not LPS. Overall, mitochondrially centered metabolic capabilities of late gestation monocytes are down-regulated revealing natural plasticity in monocyte phenotype and function that could reveal targets for improving pregnancy outcomes but also yield alternative therapeutic approaches to diverse metabolic and/or immune-mediated diseases beyond pregnancy.

S100A9 interacts with a dynamic region on CD14 to activate Toll-like receptor 4

S100A9 is a Damage Associated Molecular Pattern (DAMP) that activates inflammatory pathways via Toll-like receptor 4 (TLR4). This activity plays important homeostatic roles in tissue repair, but can also contribute to inflammatory diseases. The mechanism of activation is unknown. Here, we follow up on a previous observation that the protein CD14 is an important co-receptor that enables S100A9 to activate TLR4. Using cell-based functional assays and a combination of mutations and pharmocological perturbations, we found that CD14 must be membrane bound to potentiate TLR4 activation by S100A9. Additionally, S100A9 is sensitive to inhibitors of pathways downstream of TLR4 internalization. Together, this suggests that S100A9 induces activity via CD14-dependent internalization of TLR4. We then used mutagenesis, structural modeling, and in vitro binding experiments to establish that S100A9 binds to CD14's N-terminus in a region that overlaps with, but is not identical to, the region where CD14 binds its canonical ligand, lipopolysaccharide (LPS). In molecular dynamics simulations, this region of the protein is dynamic, allowing it to reorganize to recognize both S100A9 (a soluble protein) and LPS (a small hydrophobic molecule). Our work is the first attempt at a molecular characterization of the S100A9/CD14 interaction, bringing us one step closer to unraveling the full mechanism by which S100A9 activates TLR4/MD-2.

Association of Blast Exposure in Military Breaching with Intestinal Permeability Blood Biomarkers Associated with Leaky Gut

Injuries and subclinical effects from exposure to blasts are of significant concern in military operational settings, including tactical training, and are associated with self-reported concussion-like symptomology and physiological changes such as increased intestinal permeability (IP), which was investigated in this study. Time-series gene expression and IP biomarker data were generated from "breachers" exposed to controlled, low-level explosive blast during training. Samples from 30 male participants at pre-, post-, and follow-up blast exposure the next day were assayed via RNA-seq and ELISA. A battery of symptom data was also collected at each of these time points that acutely showed elevated symptom reporting related to headache, concentration, dizziness, and taking longer to think, dissipating ~16 h following blast exposure. Evidence for bacterial translocation into circulation following blast exposure was detected by significant stepwise increase in microbial diversity (measured via alpha-diversity p = 0.049). Alterations in levels of IP protein biomarkers (i.e., Zonulin, LBP, Claudin-3, I-FABP) assessed in a subset of these participants (n = 23) further evidenced blast exposure associates with IP. The observed symptom profile was consistent with mild traumatic brain injury and was further associated with changes in bacterial translocation and intestinal permeability, suggesting that IP may be linked to a decrease in cognitive functioning. These preliminary findings show for the first time within real-world military operational settings that exposures to blast can contribute to IP.

Serum Lipopolysaccharide-binding Protein Levels and the Incidence of Metabolic Syndrome in a General Japanese Population: the Hisayama Study

BACKGROUND

The association between chronic lipopolysaccharide exposure and the development of metabolic syndrome (MetS) is unclear. In this study we examined the association between serum lipopolysaccharide-binding protein (LBP) levels, an indicator of lipopolysaccharide exposure, and the development of MetS in a general Japanese population.

METHODS

1,869 community-dwelling Japanese individuals aged ≥40 years without MetS at baseline examination in 2002-2003 were followed up by repeated examination in 2007-2008. MetS was defined according to the Japanese criteria. Serum LBP levels were classified into quartiles (quartiles 1-4: 2.20-9.56, 9.57-10.78, 10.79-12.18, and 12.19-24.34 µg/mL, respectively). Odds ratios (ORs) for developing MetS were calculated using a logistic regression model.

RESULTS

At the follow-up survey, 159 participants had developed MetS. Higher serum LBP levels were associated with greater risk of developing MetS after multivariable adjustment for age, sex, smoking, drinking, and exercise habits (OR [95% confidence interval] for quartiles 1-4: 1.00 [reference], 2.92 [1.59-5.37], 3.48 [1.91-6.35], and 3.86 [2.12-7.03], respectively; P for trend <0.001). After additional adjustment for homeostasis model assessment of insulin resistance, this association was attenuated but remained significant (P for trend = 0.007). On the other hand, no significant association was observed after additional adjustment for serum high-sensitivity C-reactive protein (P for trend = 0.07).

CONCLUSION

In the general Japanese population, our findings suggest that higher serum LBP levels are associated with elevated risk of developing MetS. Low-grade endotoxemia could play a role in the development of MetS through systemic chronic inflammation and insulin resistance.

Reduced Lipopolysaccharide-Binding Protein (LBP) Levels Are Associated with Non-Alcoholic Fatty Liver Disease (NAFLD) and Adipose Inflammation in Human Obesity

Lipopolysaccharide (LPS) and its binding protein LBP have emerged as potential contributors to the progression from overweight/obesity to overt metabolic diseases and NAFLD. While LPS is known to activate hepatocyte inflammation, thus contributing toward NAFLD development, the role of LBP is more intricate, and recent data have shown that experimental reduction in hepatic LBP promotes NAFLD progression. In this cross-sectional investigation, we evaluated circulating LBP in relation to obesity, NAFLD, visceral adipose tissue (VAT) inflammation, and type 2 diabetes (T2D). We recruited 186 individuals (M/F: 81/105; age: 47 ± 10.4 years; BMI: 35.5 ± 8.6 kg/m2); a subgroup (n = 81) underwent bariatric surgery with intra-operative VAT and liver biopsies. LBP levels were higher in obese individuals than non-obese individuals but were inversely correlated with the parameters of glucose metabolism. Reduced LBP predicted T2D independent of age, sex, and BMI (p < 0.001). LBP levels decreased across more severe stages of hepatosteatosis and lobular inflammation, and were inversely associated with VAT inflammation signatures. In conclusion, LBP levels are increased in obese individuals and are associated with a more favorable metabolic profile and lower NAFLD/NASH prevalence. A possible explanation for these findings is that hepatic LBP production may be triggered by chronic caloric excess and facilitate LPS degradation in the liver, thus protecting these individuals from the metabolic consequences of obesity.

Increased plasma lipopolysaccharide-binding protein and altered inflammatory mediators in overweight women suggest a state of subclinical endotoxemia

Chronic low-grade inflammation has been recognized as an underlying event linking obesity to cardiovascular disease (CVD). However, inflammatory alterations in individuals who are overweight remain understudied. To provide insight, we determined the levels of key circulating biomarkers of endotoxemia and inflammation, including lipopolysaccharide-binding protein (LBP), CRP, IL-6, leptin, and adiponectin in adult female subjects (n=40) who were lean or overweight and had high cholesterol and/or high blood pressure - two important conventional risk factors for CVD. Plasma levels of LBP were significantly higher in the overweight group compared with the lean group (P=0.005). The levels of CRP were also significantly higher in overweight subjects (P=0.01), as were IL-6 (P=0.02) and leptin (P=0.002), pro-inflammatory mediators associated with cardiovascular risk. Levels of adiponectin, an adipokine with anti-inflammatory and anti-atherogenic functions, were significantly lower in the overweight group (P=0.002). The leptin/adiponectin ratio, a preferential atherogenic marker was significantly increased in women who are overweight (P=0.02). LBP, CRP, leptin, and adiponectin levels significantly correlated with BMI, but not with age and there was a significant correlation between LBP and IL-6 levels. These results reveal the presence of subclinical endotoxemia and a pro-inflammatory state in overweight women and are of interest for further studies with the goal for improved understanding of cardiovascular health risks in women.

Interactions between environmental sensitivity and gut microbiota are associated with biomarkers of stress-related psychiatric symptoms

BACKGROUND

Humans vary in their sensitivity to stressful and supportive environments and experiences. Such individual differences in environmental sensitivity are associated with mechanisms of stress-related psychiatric symptoms. In recent years, researchers have focused on bidirectional interactions in the brain-gut-microbiota axis as a neurophysiological pathway contributing to the mechanisms of stress-related psychiatric symptoms, and evidence is rapidly accumulating.

METHODS

Data on environmental sensitivity, gut microbiota, gut permeability (lipopolysaccharide-binding protein; LBP) and inflammation (C-reactive protein; CRP) were collected from 90 adults (50 % female; Mage = 42.1; SDage = 10.0). Environmental sensitivity was measured using a self-report questionnaire. Study participants' feces were analyzed, and observed operational taxonomic units for richness, Shannon's index for evenness, and phylogenetic diversity for biodiversity were evaluated as indicators of gut microbiota. In addition, participants' serum was analyzed for CRP and LBP. We investigated whether the interaction between environmental sensitivity and gut microbiota is associated with biomarkers of inflammation and gut permeability.

RESULTS

The interaction between environmental sensitivity and gut microbiota (excluding the Shannon's index) explained the levels of these biomarkers. Individuals with high environmental sensitivity displayed higher levels of CRP and LBP, when the richness and diversity of the gut microbiota was low. However, even highly susceptible individuals had lower levels of CRP and LBP, when the richness and diversity of the gut microbiota was high.

CONCLUSIONS

Our study indicates that high environmental sensitivity can be a risk factor for inflammation and gut permeability, when the gut microbiota diversity is low, suggesting a brain-gut-microbiota axis interaction.

Increased plasma lipopolysaccharide-binding protein and altered inflammatory mediators in overweight women suggest a state of subclinical endotoxemia

Chronic low-grade inflammation has been recognized as an underlying event linking obesity to cardiovascular disease (CVD). However, inflammatory alterations in individuals who are overweight remain understudied. To provide insight, we determined the levels of key circulating biomarkers of endotoxemia and inflammation, including lipopolysaccharide-binding protein (LBP), CRP, IL-6, leptin, and adiponectin in adult female subjects (n = 20) who were lean or overweight and had high cholesterol and/or high blood pressure - two important conventional risk factors for CVD. Plasma levels of LBP (a recognized marker of metabolic endotoxemia in obesity) were significantly higher in the overweight group compared with the lean group (P = 0.005). The levels of CRP, a general marker of inflammation, were also significantly higher in overweight subjects (P = 0.01), as were IL-6 (P = 0.02) and leptin (P = 0.002), pro-inflammatory mediators associated with cardiovascular risk. Levels of adiponectin, an adipokine with anti-inflammatory and anti-atherogenic functions, were significantly lower in the overweight group (P = 0.002). The leptin/adiponectin ratio, a preferential atherogenic marker was significantly increased in women who are overweight (P = 0.02). LBP, CRP, leptin, and adiponectin levels significantly correlated with BMI, but not with age. These results reveal the presence of subclinical endotoxemia and a pro-inflammatory state in overweight women and are of interest for further studies with the goal for improved understanding of women's cardiovascular health.

Uncovering Novel Biomarkers of Inflammation as Potential Screening Targets of Disease Risk in Healthcare Shift Workers: A Pilot Study

Shift work, experienced by nearly 30% of the U.S. workforce, is hazardous to health and has become a pervasive labor practice in the healthcare sector worldwide. It increases the risk of stroke, diabetes, cancer, and cardiovascular disease. Nonetheless, specific screening targets for shift workers still need to be defined. In this study, we have begun uncovering these targets as specific low-grade systemic inflammation markers and functional endotoxin-elicited responses that may foreshadow disease risk in shift workers. One hundred four participants (normothermic and normotensive) were healthy, non-smoking, and drug- and medication-free volunteers recruited from Atlanta area hospitals and medical schools. We assessed the concentration of three proteins in plasma samples from day workers and shift workers (lipopolysaccharide-binding protein, IL-10, and TNF-α), and the relationship between these baseline biomarkers and their response to an ex-vivo endotoxin challenge. We show that shift work increases low-grade systemic inflammation and disrupts discrete endotoxin responses. As shift work exposure increases, the correlation between low-grade systemic inflammation markers and their endotoxin responses was disrupted; this effect was more robust for TNF-α than for IL-10. With increased shift work exposure, these events, alone or combined, represent potential systemic and functional signals that may be harnessed to develop screening tools to identify at-risk individuals.

Depression, Inflammation, and Intestinal Permeability: Associations with Subjective and Objective Cognitive Functioning throughout Breast Cancer Survivorship

About one-in-three breast cancer survivors have lingering cognitive complaints and objective cognitive impairment. Chronic inflammation and intestinal permeability (i.e., leaky gut), two risk factors for cognitive decline, can also fuel depression-another vulnerability for cognitive decline. The current study tested whether depression accompanied by high levels of inflammation or intestinal permeability predicted lower subjective and objective cognitive function in breast cancer survivors. We combined data from four breast cancer survivor studies (n = 613); some had repeated measurements for a total of 1015 study visits. All participants had a blood draw to obtain baseline measures of lipopolysaccharide binding protein-a measure of intestinal permeability, as well as three inflammatory markers that were incorporated into an inflammatory index: C-reactive protein, interleukin-6, and tumor necrosis factor-α. They reported depressive symptoms on the Center for Epidemiological Studies depression scale (CES-D), and a binary variable indicated clinically significant depressive symptoms (CES-D ≥ 16). The Kohli (749 observations) and the Breast Cancer Prevention Trial (591 observations) scales assessed subjective cognitive function. Objective cognitive function tests included the trail-making test, Hopkins verbal learning test, Conners continuous performance test, n-back test, FAS test, and animal-naming test (239-246 observations). Adjusting for education, age, BMI, cancer treatment type, time since treatment, study visit, and fatigue, women who had clinically elevated depressive symptoms accompanied by heightened inflammation or intestinal permeability reported poorer focus and marginally poorer memory. However, poorer performance across objective cognitive measures was not specific to inflammation-associated depression. Rather, there was some evidence of lower verbal fluency; poorer attention, verbal learning and memory, and working memory; and difficulties with visuospatial search among depressed survivors, regardless of inflammation. By themselves, inflammation and intestinal permeability less consistently predicted subjective or objective cognitive function. Breast cancer survivors with clinically significant depressive symptoms accompanied by either elevated inflammation or intestinal permeability may perceive greater cognitive difficulty, even though depression-related objective cognitive deficits may not be specific to inflammation- or leaky-gut-associated depression.

Intestinal microbiome characterization of adult Brazilian men with psoriasis compared to omnivore and vegetarian controls

BACKGROUND

Psoriasis is a chronic inflammatory disease associated with systemic inflammation and comorbidities. Changes in the composition of the intestinal microbiome are involved in the pathogenesis of inflammatory diseases and metabolic syndrome. Characterizing the intestinal microbiome of patients with psoriasis may be relevant for the understanding of its clinical course and comorbidity prevention.

OBJECTIVE

To characterize the intestinal microbiome of men with psoriasis compared to omnivore and vegetarian controls (without psoriasis).

METHOD

Cross-sectional study of 42 adult males: 21 omnivores with psoriasis; and controls: 14 omnivores and 7 vegetarian individuals. The characterization of the intestinal microbiome was performed by metagenomic analysis. Serum levels of lipopolysaccharide-binding protein (LPB) and C-reactive protein (CRP) were evaluated.

RESULTS

The groups differed from each other regarding nutritional aspects and microbiome; individuals with psoriasis had a higher consumption of protein and lower consumption of fibers. Levels of LPB, CRP, and the Firmicutes/Bacteroidetes ratio were higher in the group with psoriasis than in the vegetarian group (p<0.05). The genera Prevotella, Mogibacterium, Dorea, Bifidobacterium and Coprococcus, differed in the group with psoriasis compared to vegetarians; the genera Mogibacterium, Collinsella and Desulfovibrio differed from omnivores. A microbiome pattern linked to psoriasis (plsPSO) was identified, which was associated with higher LPB levels (rho=0.39; p=0.02), and lower dietary fiber intake (rho=-0.71; p<0.01).

STUDY LIMITATIONS

Only adult men were evaluated.

CONCLUSION

A difference was identified in the intestinal microbiome of adult men with psoriasis when compared to healthy omnivores and vegetarian controls. The identified microbiome pattern was correlated with dietary fiber intake and serum levels of LPB.

Milk-Fat-Globule-Membrane-Enriched Dairy Milk Compared with a Soy-Lecithin-Enriched Beverage Did Not Adversely Affect Endotoxemia or Biomarkers of Gut Barrier Function and Cardiometabolic Risk in Adults with Metabolic Syndrome: A Randomized Controlled Crossover Trial

Full-fat dairy milk may protect against cardiometabolic disorders, due to the milk fat globule membrane (MFGM), through anti-inflammatory and gut-health-promoting activities. We hypothesized that a MFGM-enriched milk beverage (MEB) would alleviate metabolic endotoxemia in metabolic syndrome (MetS) persons by improving gut barrier function and glucose tolerance. In a randomized crossover trial, MetS persons consumed for two-week period a controlled diet with MEB (2.3 g/d milk phospholipids) or a comparator beverage (COMP) formulated with soy phospholipid and palm/coconut oil. They then provided fasting blood and completed a high-fat/high-carbohydrate test meal challenge for evaluating postprandial metabolism and intestinal permeability. Participants had no adverse effects and achieved high compliance, and there were no between-trial differences in dietary intakes. Compared with COMP, fasting endotoxin, glucose, incretins, and triglyceride were unaffected by MEB. The meal challenge increased postprandial endotoxin, triglyceride, and incretins, but were unaffected by MEB. Insulin sensitivity; fecal calprotectin, myeloperoxidase, and short-chain fatty acids; and small intestinal and colonic permeability were also unaffected by MEB. This short-term study demonstrates that controlled administration of MEB in MetS persons does not affect gut barrier function, glucose tolerance, and other cardiometabolic health biomarkers, which contradicts observational evidence that full-fat milk heightens cardiometabolic risk. Registered at ClinicalTrials.gov (NCT03860584).

Lipopolysaccharide-binding protein and future Parkinson's disease risk: a European prospective cohort

INTRODUCTION

Lipopolysaccharide (LPS) is the outer membrane component of Gram-negative bacteria. LPS-binding protein (LBP) is an acute-phase reactant that mediates immune responses triggered by LPS and has been used as a blood marker for LPS. LBP has recently been indicated to be associated with Parkinson's disease (PD) in small-scale retrospective case-control studies. We aimed to investigate the association between LBP blood levels with PD risk in a nested case-control study within a large European prospective cohort.

METHODS

A total of 352 incident PD cases (55% males) were identified and one control per case was selected, matched by age at recruitment, sex and study center. LBP levels in plasma collected at recruitment, which was on average 7.8 years before diagnosis of the cases, were analyzed by enzyme linked immunosorbent assay. Odds ratios (ORs) were estimated for one unit increase of the natural log of LBP levels and PD incidence by conditional logistic regression.

RESULTS

Plasma LBP levels were higher in prospective PD cases compared to controls (median (interquartile range) 26.9 (18.1-41.0) vs. 24.7 (16.6-38.4) µg/ml). The OR for PD incidence per one unit increase of log LBP was elevated (1.46, 95% CI 0.98-2.19). This association was more pronounced among women (OR 2.68, 95% CI 1.40-5.13) and overweight/obese subjects (OR 1.54, 95% CI 1.09-2.18).

CONCLUSION

The findings suggest that higher plasma LBP levels may be associated with an increased risk of PD and may thus pinpoint to a potential role of endotoxemia in the pathogenesis of PD, particularly in women and overweight/obese individuals.

Effects of an inulin fiber diet on the gut microbiome, colon, and inflammatory biomarkers in aged mice

Due to the increasing human life expectancy and limited supply of healthcare resources, strategies to promote healthy aging and reduce associated functional deficits are of public health importance. The gut microbiota, which remodels with age, has been identified as a significant contributor to the aging process that is modifiable by diet. Since prebiotic dietary components such as inulin have been shown to impart positive benefits with regards to aging, this study used C57Bl6 mice to investigate whether 8 weeks on a 2.5 % inulin enhanced AIN-93M 1 % cellulose diet could offset age-associated changes in gut microbiome composition and markers of colon health and systemic inflammation in comparison to a AIN 93M 1 % cellulose diet with 0 % inulin. Our results demonstrated that, in both age groups, dietary inulin significantly increased production of butyrate in the cecum and induced changes in the community structure of the gut microbiome but did not significantly affect systemic inflammation or other markers of gastrointestinal health. Aged mice had different and less diverse microbiomes when compared to adult mice and were less sensitive to inulin-induced microbiome community shifts, evidenced by longitudinal differences in differentially abundant taxa and beta diversity. In aged mice, inulin restored potentially beneficial taxa including Bifidobacterium and key butyrate producing genera (e.g. Faecalibaculum). Despite inducing notable taxonomic changes, however, the 2.5 % inulin diet reduced alpha diversity in both age groups and failed to reduce overall community compositional differences between age groups. In conclusion, a 2.5 % inulin enhanced diet altered gut microbiome α and β diversity, composition, and butyrate production in both adult and aged mice, with more potent effects on β diversity and greater number of taxa significantly altered in adult mice. However, significant benefits in age-associated changes in systemic inflammation or intestinal outcomes were not detected.

Association between gut permeability, brain volume, and cognition in healthy participants and patients with schizophrenia spectrum disorder

INTRODUCTION

The barrier function of the gut is important for many organs and systems, including the brain. If gut permeability increases, bacterial fragments may enter the circulation, giving rise to increased systemic inflammation. Increases in bacterial translocation are reflected in higher values of blood markers, including lipopolysaccharide binding protein (LBP) and soluble cluster of differentiation 14 (sCD14). Some pioneer studies showed a negative association between bacterial translocation markers and brain volumes, but this association remains scarcely investigated. We investigate the effect of bacterial translocation on brain volumes and cognition in both healthy controls and patients with a schizophrenia spectrum disorder (SSD).

MATERIALS AND METHODS

Healthy controls (n = 39) and SSD patients (n = 72) underwent an MRI-scan, venipuncture and cognition assessments. We investigated associations between LBP and sCD14 and brain volumes (intracranial volume, total brain volume, and hippocampal volume) using linear regression. We then associated LBP and sCD14 to cognitive function using a mediation analysis, with intracranial volume as mediator.

RESULTS

Healthy controls showed a negative association between hippocampal volume and LBP (b = -0.11, p = .04), and intracranial volume and sCD14 (b = -0.25, p = .07). Both markers were indirectly associated with lower cognitive functioning in healthy controls (LBP: b = -0.071, p = .028; sCD14: b = -0.213, p = .052), mediated by low intracranial volume. In the SSD patients, these associations were markedly less present.

CONCLUSION

These findings extend earlier studies suggesting that increased bacterial translocation may negatively affect brain volume, which indirectly impacts cognition, even in this young healthy group. If replicated, this finding stresses the importance of a healthy gut for the development and optimal functioning of the brain. Absence of these associations in the SSD group may indicate that other factors such as allostatic load, chronic medication use and interrupted educational carrier had larger impact and attenuated the relative contribution of bacterial translocation.

Circulating markers of microbial translocation and host response to bacteria with risk of colorectal cancer: a prospective, nested case-control study in men

BACKGROUND

Gut microbial dysbiosis contributes to colorectal cancer (CRC) pathogenesis, possibly mediated in part by increased intestinal permeability to endotoxin lipopolysaccharide (LPS), microbial translocation, and subsequent endotoxemia and inflammation. However, epidemiologic evidence linking circulating markers of microbial translocation with CRC risk is limited.

METHODS

We conducted a prospective, nested case-control study of 261 incident CRC cases and 261 controls (matched on age and time of blood draw) among 18,159 men with pre-diagnostic blood specimens in the Health Professionals Follow-Up Study (1993-2009). We examined three complementary markers of microbial translocation and host response to bacteria, including LPS-binding protein (LBP), soluble CD14 (sCD14), and endotoxincore antibody (EndoCAb) immunoglobulin M (IgM), with subsequent risk of CRC. Unconditional logistic regressions were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

FINDINGS

Pre-diagnostic circulating levels of sCD14 were associated with a higher risk of incident CRC. Compared to men in the lowest quartile, the multivariable OR was 1.90 (95% CI, 1.13-3.22) for men in the highest quartile (OR _{per standard deviation [SD] increase}, 1.28; 95%CI 1.06-1.53; P_trend = 0.01). This positive association remained similar after adjusting for C-reactive protein, interleukin-6, and soluble tumor necrosis factor receptor-2, and within strata of putative CRC risk factors. We also observed a suggestive inverse association between EndoCAb IgM and risk of CRC (OR _{per SD increase}, 0.84; 95%CI 0.69-1.02; P_trend = 0.09).

INTERPRETATION

Microbial translocation and host response to bacteria, as reflected by sCD14, is associated with risk of incident CRC in men.

FUNDING

US National Institutes of Health.

Deficiency of lipopolysaccharide binding protein facilitates adipose browning, glucose uptake and oxygen consumption in mouse embryonic fibroblasts via activating PI3K/Akt/mTOR pathway and inhibiting autophagy

This study aimed to explore the role of lipopolysaccharide-binding protein (LBP) in adipose browning. Mouse embryonic fibroblasts (MEFs) were treated with differentiation induction reagents and Perifosine (Akt inhibitor), with the transfection of Atg5, short hairpin RNA targeting LBP (shLBP), and Atg5 (shAtg5). The expression levels of LBP, inflammatory markers , brown fat markers, lipid metabolism marker, autophagy markers, insulin signaling-related molecules , p-mTOR, mTOR, p-Akt, Akt, p-PI3K, and PI3K were quantified or determined by Western blot, qRT-PCR, and immunofluorescence assay. The formation of lipid was examined through Oil red O staining assay. The consumption of oxygen was assessed using a Seahorse XF96 analyzer, and the uptake of glucose was evaluated by [³H]-2-deoxy-D-glucose uptake assay. Deficiency of LBP promoted adipose browning, oxygen consumption, glucose uptake, and insulin sensitivity in differentiated MEFs, where it inhibited inflammation and autophagy. All of the effects above were reversed by Atg5 overexpression. Meanwhile, the knockdown of Atg5 strengthened the activation of PI3K/Akt/mTOR pathway induced by the depletion of LBP, while Perifosine partly reversed the activation of differentiated MEFs. The knockdown of LBP facilitated adipose browning, glucose uptake, and oxygen consumption in MEFs via the activation of PI3K/Akt/mTOR pathway and the inhibition of autophagy.

Association of Plasma Lipopolysaccharide-Binding Protein Concentration with Dietary Factors, Gut Microbiota, and Health Status in the Japanese General Adult Population: A Cross-Sectional Study

The influx of intestinal bacteria-derived lipopolysaccharide (LPS) into the blood has attracted attention as a cause of diseases. The aim of this study is investigating the associations between the influx of LPS, dietary factors, gut microbiota, and health status in the general adult population. Food/nutrient intake, gut microbiota, health status and plasma LPS-binding protein (LBP; LPS exposure indicator) were measured in 896 residents (58.1% female, mean age 54.7 years) of the rural Iwaki district of Japan, and each correlation was analyzed. As the results, plasma LBP concentration correlated with physical (right/left arms' muscle mass [β = -0.02, -0.03]), renal (plasma renin activity [β = 0.27], urine albumin creatinine ratio [β = 0.50]), adrenal cortical (cortisol [β = 0.14]), and thyroid function (free thyroxine [β = 0.05]), iron metabolism (serum iron [β = -0.14]), and markers of lifestyle-related diseases (all Qs < 0.20). Plasma LBP concentration were mainly negatively correlated with vegetables/their nutrients intake (all βs ≤ -0.004, Qs < 0.20). Plasma LBP concentration was positively correlated with the proportion of Prevotella (β = 0.32), Megamonas (β = 0.56), and Streptococcus (β = 0.65); and negatively correlated with Roseburia (β = -0.57) (all Qs < 0.20). Dietary factors correlated with plasma LBP concentration correlated with positively (all βs ≥ 0.07) or negatively (all βs ≤ -0.07) the proportion of these bacteria (all Qs < 0.20). Our results suggested that plasma LBP concentration in the Japanese general adult population was associated with various health issues, and that dietary habit was associated with plasma LBP concentration in relation to the intestinal bacteria.

Fatty acid overproduction by gut commensal microbiota exacerbates obesity

Although recent studies have highlighted the impact of gut microbes on the progression of obesity and its comorbidities, it is not fully understood how these microbes promote these disorders, especially in terms of the role of microbial metabolites. Here, we report that Fusimonas intestini, a commensal species of the family Lachnospiraceae, is highly colonized in both humans and mice with obesity and hyperglycemia, produces long-chain fatty acids such as elaidate, and consequently facilitates diet-induced obesity. High fat intake altered the expression of microbial genes involved in lipid production, such as the fatty acid metabolism regulator fadR. Monocolonization with a FadR-overexpressing Escherichia coli exacerbated the metabolic phenotypes, suggesting that the change in bacterial lipid metabolism is causally involved in disease progression. Mechanistically, the microbe-derived fatty acids impaired intestinal epithelial integrity to promote metabolic endotoxemia. Our study thus provides a mechanistic linkage between gut commensals and obesity through the overproduction of microbe-derived lipids.

Lipopolysaccharide-binding protein and bone health: data from a population-based sample of men

We aimed to investigate the association between serum lipopolysaccharide-binding protein (LBP) and bone health in men. LBP was associated with lower bone density at the mid-forearm and the quantitative heel ultrasound measure, broadband ultrasound attenuation, for heavier participants. Data do not support clear associations between serum LBP and bone health.

INTRODUCTION

The objective of this study was to investigate the association between serum lipopolysaccharide-binding protein (LBP) and potential downstream effects on skeletal density, quality, and turnover in a population-based sample of men.

METHODS

This cross-sectional study utilised data from 1149 men (aged 20-96 year) enrolled in the Geelong Osteoporosis Study. Blood samples were obtained and lipopolysaccharide-binding protein (LBP), bone resorption marker, C-telopeptide (CTx), and formation marker, type 1 procollagen amino-terminal-propeptide (P1NP), were measured. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry. Stiffness Index (SI), broadband ultrasound attenuation (BUA), and speed of sound (SOS) were derived from quantitative heel ultrasound (QUS). Linear regression models were developed to test associations between log-transformed LBP (ln-LBP), BMD, QUS, and bone turnover, after adjusting for potential covariates.

RESULTS

Serum LBP ranged from 1.07-208.53 ng/mL (median 16.53 ng/mL). Those with higher levels were older, less mobile, and had lower BMD at the mid-forearm, otherwise, groups were similar. Before and after adjustment for age, ln-LBP was associated with lower BMD at the spine, total body, and mid-forearm. Further adjustment for weight attenuated associations at the spine and total body, yet the relationship at the mid-forearm was sustained (β - 0.014 ± 0.004, p = 0.001). SOS and SI were not associated with ln-LBP either before or after adjustment for age; however, weight was identified as an effect modifier in the relationship between ln-LBP and BUA. An association was observed for those weighing greater than 82.7 kg (β 3.366 ± 0.929, p < 0.001), after adjustment for potential covariates. Neither bone turnover marker was associated with ln-LBP.

CONCLUSION

Our data do not support a clear association between serum LBP and measures of bone health in this sample of men.

Antibiotics in the pathogenesis of diabetes and inflammatory diseases of the gastrointestinal tract

Antibiotic use is increasing worldwide. However, the use of antibiotics is clearly associated with changes in gut microbiome composition and function, and perturbations have been identified as potential environmental risk factors for chronic inflammatory disorders of the gastrointestinal tract. In this Review, we examine the association between the use of antibiotics and the onset and development of both type 1 and type 2 diabetes, inflammatory bowel disease, including ulcerative colitis and Crohn's disease, as well as coeliac disease and eosinophilic oesophagitis. We discuss the key findings of epidemiological studies, provide mechanistic insights into the pathways by which the gut microbiota might contribute to these diseases, and assess clinical trials investigating the effects of antibiotics. Such studies indicate that antibiotic exposures, varying in type, timing and dosage, could explain differences in disease risk. There seems to be a critical window in early life in which perturbation of the microbiome has a substantial effect on disease development. Identifying the antibiotic-perturbed gut microbiota as a factor that contributes to the pathophysiology of these inflammatory disorders might stimulate new approaches to prevention, diagnosis and treatment.

Anti-inflammatory mechanisms of polyphenols in adipose tissue: role of gut microbiota, intestinal barrier integrity and zinc homeostasis

Obesity is associated with an imbalance of micro-and macro-nutrients, gut dysbiosis, and a "leaky" gut phenomenon. Polyphenols, such as curcumin, resveratrol, and anthocyanins may alleviate the systemic effects of obesity, potentially by improving gut microbiota, intestinal barrier integrity (IBI), and zinc homeostasis. The essential micronutrient zinc plays a crucial role in the regulation of enzymatic processes, including inflammation, maintenance of the microbial ecology, and intestinal barrier integrity. In this review, we focus on IBI- which prevents intestinal lipopolysaccharide (LPS) leakage - as a critical player in polyphenol-mediated protective effects against obesity-associated white adipose tissue (WAT) inflammation. This occurs through mechanisms that block the movement of the bacterial endotoxin LPS across the gut barrier. Available research suggests that polyphenols reduce WAT and systemic inflammation via crosstalk with inflammatory NF-κB, the mammalian target of rapamycin (mTOR) signaling and zinc homeostasis.

The role of gut-derived oxidized lipids and bacterial lipopolysaccharide in systemic inflammation and atherosclerosis

PURPOSE OF REVIEW

This review explores mechanisms by which gut-derived bacteriallipopolysaccharide (LPS) and oxidized phospholipids contribute to chronic systemic inflammation and atherosclerosis.

RECENT FINDINGS

Gut-derived LPS enters through the small intestine via two distinct pathways that involve high density lipoproteins (HDL) and chylomicrons. Gut-derived LPS can bind to the LPS-binding protein (LBP) and to HDL 3 in the small intestine and travel through the portal vein to the liver where it does not elicit an inflammatory reaction, and is inactivated or it can bind to HDL 2 and travel through the portal vein to the liver where it elicits an inflammatory reaction. Alternatively, in the small intestine, LPS can bind to LBP and chylomicrons and travel through the lymphatics to the systemic circulation and enhance inflammatory processes including atherosclerosis. Oxidized phospholipids formed in the small intestine regulate the levels and uptake of LPS in small intestine by regulating antimicrobial proteins such as intestinal alkaline phosphatase. Gut-derived LPS and oxidized phospholipids may be responsible for the persistent inflammation seen in some persons with human immunodeficiency virus on potent antiretroviral therapy with undetectable virus levels.

SUMMARY

By targeting gut-derived oxidized phospholipids, the uptake of gut-derived LPS may be reduced to decrease systemic inflammation and atherosclerosis.

Exploring interleukin-6, lipopolysaccharide-binding protein and brain-derived neurotrophic factor following 12 weeks of adjunctive minocycline treatment for depression

This study aimed to explore effects of adjunctive minocycline treatment on inflammatory and neurogenesis markers in major depressive disorder (MDD). Serum samples were collected from a randomised, placebo-controlled 12-week clinical trial of minocycline (200 mg/day, added to treatment as usual) for adults (n = 71) experiencing MDD to determine changes in interleukin-6 (IL-6), lipopolysaccharide binding protein (LBP) and brain derived neurotrophic factor (BDNF). General Estimate Equation modelling explored moderation effects of baseline markers and exploratory analyses investigated associations between markers and clinical outcomes. There was no difference between adjunctive minocycline or placebo groups at baseline or week 12 in the levels of IL-6 (week 12; placebo 2.06 ± 1.35 pg/ml; minocycline 1.77 ± 0.79 pg/ml; p = 0.317), LBP (week 12; placebo 3.74 ± 0.95 µg/ml; minocycline 3.93 ± 1.33 µg/ml; p = 0.525) or BDNF (week 12; placebo 24.28 ± 6.69 ng/ml; minocycline 26.56 ± 5.45 ng/ml; p = 0.161). Higher IL-6 levels at baseline were a predictor of greater clinical improvement. Exploratory analyses suggested that the change in IL-6 levels were significantly associated with anxiety symptoms (HAMA; p = 0.021) and quality of life (Q-LES-Q-SF; p = 0.023) scale scores. No other clinical outcomes were shown to have this mediation effect, nor did the other markers (LBP or BDNF) moderate clinical outcomes. There were no overall changes in IL-6, LBP or BDNF following adjunctive minocycline treatment. Exploratory analyses suggest a potential role of IL-6 on mediating anxiety symptoms with MDD. Future trials may consider enrichment of recruitment by identifying several markers or a panel of factors to better represent an inflammatory phenotype in MDD with larger sample size.

Cellular senescence and the tumor microenvironment

The senescence‐associated secretory phenotype (SASP), where senescent cells produce a variety of secreted proteins including inflammatory cytokines, chemokines, matrix remodelling factors, growth factors and so on, plays pivotal but varying roles in the tumour microenvironment. The effects of SASP on the surrounding microenvironment depend on the cell type and process of cellular senescence induction, which is often associated with innate immunity. Via SASP‐mediated paracrine effects, senescent cells can remodel the surrounding tissues by modulating the character of adjacent cells, such as stromal, immune cells, as well as cancer cells. The SASP is associated with both tumour‐suppressive and tumour‐promoting effects, as observed in senescence surveillance effects (tumour‐suppressive) and suppression of anti‐tumour immunity in most senescent cancer‐associated fibroblasts and senescent T cells (tumour‐promoting). In this review, we discuss the features and roles of senescent cells in tumour microenvironment with emphasis on their context‐dependency that determines whether they promote or suppress cancer development. Potential usage of recently developed drugs that suppress the SASP (senomorphics) or selectively kill senescence cells (senolytics) in cancer therapy are also discussed.

Linoleic Acid-Rich Oil Alters Circulating Cardiolipin Species and Fatty Acid Composition in Adults: A Randomized Controlled Trial

SCOPE

Higher circulating linoleic acid (LA) and muscle-derived tetralinoleoyl-cardiolipin (LA₄ CL) are each associated with decreased cardiometabolic disease risk. Mitochondrial dysfunction occurs with low LA₄ CL. Whether LA-rich oil fortification can increase LA₄ CL in humans is unknown. The aims of this study are to determine whether dietary fortification with LA-rich oil for 2 weeks increases: 1) LA in plasma, erythrocytes, and peripheral blood mononuclear cells (PBMC); and 2) LA₄ CL in PBMC in adults.

METHODS AND RESULTS

In this randomized controlled trial, adults are instructed to consume one cookie per day delivering 10 g grapeseed (LA-cookie, N = 42) or high oleate (OA) safflower (OA-cookie, N = 42) oil. In the LA-cookie group, LA increases in plasma, erythrocyte, and PBMC by 6%, 7%, and 10% respectively. PBMC and erythrocyte OA increase by 7% and 4% in the OA-cookie group but is unchanged in the plasma. PBMC LA₄ CL increases (5%) while LA₃ OA₁ CL decreases (7%) in the LA-cookie group but are unaltered in the OA-cookie group.

CONCLUSIONS

LA-rich oil fortification increases while OA-oil has no effect on LA₄ CL in adults. Because LA-rich oil fortification reduces cardiometabolic disease risk and increases LA₄ CL, determining whether mitochondrial dysfunction is repaired through dietary fortification is warranted.

"HIIT the Inflammation": Comparative Effects of Low-Volume Interval Training and Resistance Exercises on Inflammatory Indices in Obese Metabolic Syndrome Patients Undergoing Caloric Restriction

Exercise is a cornerstone in metabolic syndrome (MetS) treatment. However, the effects of low-volume exercise modalities on MetS-associated low-grade inflammation are unclear. A total of 106 MetS patients (53.7 ± 11.4 years) were randomized to low-volume high-intensity interval training (LOW-HIIT, 14 min/session), single-set resistance training (1-RT, ~15 min/session), whole-body electromyostimulation (WB-EMS, 20 min/session), three-set resistance training (3-RT, ~50 min/session), each performed 2 ×/week for 12 weeks, or a control group (CON). All groups received nutritional counseling for weight loss. Inflammatory and cardiometabolic indices were analyzed pre- and post-intervention. All groups significantly reduced body weight by an average of 3.6%. Only LOW-HIIT reduced C-reactive protein (CRP) (−1.6 mg/L, p = 0.001) and interleukin-6 (−1.1 pg/mL, p = 0.020). High-sensitivity CRP and lipopolysaccharide-binding protein decreased following LOW-HIIT (−1.4 mg/L, p = 0.001 and −2.1 ng/mL, p = 0.004) and 3-RT (−0.6 mg/L, p = 0.044 and −2.0 ng/mL, p < 0.001). MetS severity score improved with LOW-HIIT (−1.8 units, p < 0.001), 1-RT (−1.6 units, p = 0.005), and 3-RT (−2.3 units, p < 0.001). Despite similar effects on body weight, low-volume exercise modalities have different impact on inflammatory and cardiometabolic outcomes in MetS patients. LOW-HIIT has superior efficacy for improving inflammation compared to 1-RT and WB-EMS. Resistance-based exercise appears to require a higher volume to promote beneficial impact on inflammation.

Lipopolysaccharide and the gut microbiota: Considering structural variation

Systemic inflammation is associated with chronic disease and is purported to be a main pathogenic mechanism underlying metabolic conditions. Microbes harbored in the host gastrointestinal tract release signaling byproducts from their cell wall, such as lipopolysaccharides (LPS), which can act locally and, after crossing the gut barrier and entering circulation, also systemically. Defined as metabolic endotoxemia, elevated concentrations of LPS in circulation are associated with metabolic conditions and chronic disease. As such, measurement of LPS is highly prevalent in animal and human research investigating these states. Indeed, LPS can be a potent stimulant of host immunity but this response depends on the microbial species' origin, a parameter often overlooked in both preclinical and clinical investigations. Indeed, the lipid A portion of LPS is mutable and comprises the main virulence and endotoxic component, thus contributing to the structural and functional diversity among LPSs from microbial species. In this review, we discuss how such structural differences in LPS can induce differential immunological responses in the host.

Intestinal permeability before and after albendazole treatment in low and high socioeconomic status schoolchildren in Makassar, Indonesia

Intestinal helminths are highly prevalent in low-SES children and could contribute to poor health outcomes either directly or via alteration of the gut microbiome and gut barrier function. We analysed parasitic infections and gut microbiota composition in 325 children attending high- and low-SES schools in Makassar, Indonesia before and after albendazole treatment. Lactulose/Mannitol Ratio (LMR, a marker of gut permeability); I-FABP (a surrogate marker of intestinal damage) as well as inflammatory markers (LBP) were measured. Helminth infections were highly prevalent (65.6%) in low-SES children. LMR and I-FABP levels were higher in low-SES children (geomean (95%CI): 4.03 (3.67-4.42) vs. 3.22 (2.91-3.57); p. adj < 0.001; and 1.57 (1.42-1.74) vs. 1.25 (1.13-1.38); p. adj = 0.02, respectively) while LBP levels were lower compared to the high-SES (19.39 (17.09-22.01) vs. 22.74 (20.07-26.12); p.adj = 0.01). Albendazole reduced helminth infections in low-SES and also decreased LMR with 11% reduction but only in helminth-uninfected children (estimated treatment effect: 0.89; p.adj = 0.01). Following treatment, I-FABP decreased in high- (0.91, p.adj < 0.001) but increased (1.12, p.adj = 0.004) in low-SES children. Albendazole did not alter the levels of LBP. Microbiota analysis showed no contribution from specific bacterial-taxa to the changes observed. Intestinal permeability and epithelial damage are higher while peripheral blood inflammatory marker is lower in children of low-SES in Indonesia. Furthermore, treatment decreased LMR in helminth-uninfected only.

The gut connection: Intestinal permeability as a pathway from breast cancer survivors' relationship satisfaction to inflammation across treatment

BACKGROUND

Breast cancer survivors are prone to weakened gut barriers, allowing bacteria to migrate into the blood stream. Gut permeability fuels inflammation, which, among survivors, can elevate risk for comorbid disease development, cancer recurrence, and a poor quality of life; however, survivors' satisfying relationships can provide health benefits. This longitudinal study used a conceptual model addressing how intimate relationships is associated with health through changes in gut permeability and inflammation.

METHOD

Breast cancer survivors (n = 139, stages 0-IIIC) completed a baseline visit before treatment and two follow-up visits 6 and 18 months after treatment ended. Women who had an abnormal breast cancer test followed by a benign diagnosis completed visits within a comparable timeframe (noncancer patient controls; n = 69). All women completed questionnaires assessing their relationship satisfaction and provided blood samples to assess two bacterial endotoxin biomarkers, lipopolysaccharide-binding protein (LBP) and soluble CD14 (sCD14), as well as C-reactive protein (CRP) and interleukin 6 (IL-6).

RESULTS

Within-person multilevel mediation analyses showed that when a survivor's relationship satisfaction was higher than usual, her own LBP and LBP/sCD14 were lower, which was associated with lower than her own average CRP and IL-6 (95% CIs [-0.0104, -0.0002]). IL-6 was also higher when older survivors, but not younger survivors, experienced higher than usual intestinal permeability (p = .001). These effects of satisfying relationships held after accounting for cancer-related and behavioral factors. Post-hoc analyses showed LBP, sCD14, and LBP/sCD14 were associated with CRP for the cancer survivors, but only LBP and LBP/sCD14 were linked to CRP among the noncancer control patients.

CONCLUSION

The gut environment is a new promising candidate for understanding a relationship's long-term health impact, particularly among those with elevated health risks. Survivors may reap multiple physiological benefits from satisfying relationships.

A behavioral weight-loss intervention, but not metformin, decreases a marker of gut barrier permeability: results from the SPIRIT randomized trial

Background/Objectives:

Lipopolysaccharide-binding protein (LBP), a biomarker of gut barrier permeability to lipopolysaccharides, is higher in adults with obesity and type 2 diabetes. Behavioral weight loss and metformin have distinct effects on the gut microbiome, but their impact on gut permeability to lipopolysaccharides is unknown. This study’s objective was to determine the effects of a behavioral weight loss intervention or metformin treatment on plasma LBP.

Subjects/Methods:

SPIRIT was a randomized trial of adults with overweight or obesity. Participants were randomized to one of three arms: metformin treatment, coach-directed behavioral weight loss on a DASH diet, or self-directed care (control). Of 121 participants, a random subset (n=88) was selected to have LBP measured at baseline, 6-months, and 12-months post intervention. Intervention effects on LBP over time were assessed using generalized estimating equations (GEE). We also examined whether the intervention effects were modified by change in diet and weight.

Results:

Arms were balanced by sex (83% female), race (51% white), and age (mean 60 years), with no differences in baseline LBP (median 4.23 μg/mL). At 1 year, mean weight change was −3.00% in the metformin arm, −3.02% in the coach-directed behavioral weight-loss arm, and +0.33% in the self-directed (control) arm. The corresponding change in LBP was +1.03, −0.98, +1.03 μg/mL. The behavioral weight-loss reduced LBP compared to self-directed care (β=−0.17, 95% CI: −0.33 to −0.01); no other between-arm comparisons were significant. Participants who reduced dietary fat showed the greatest reductions in 6-month LBP (β=−2.84, 95% CI: −5.17 to −0.50).

Conclusions:

Despite similar weight loss in the behavioral weight loss and metformin arms, only the behavioral weight loss intervention reduced LBP compared to control. Lifestyle weight loss interventions that promote a DASH diet may be effective at reducing gut barrier permeability to lipopolysaccharides.

Shift Work Predicts Increases in Lipopolysaccharide-Binding Protein, Interleukin-10, and Leukocyte Counts in a Cross-Sectional Study of Healthy Volunteers Carrying Low-Grade Systemic Inflammation

The disruption of inflammatory responses is a potential mechanism behind the harmful effects of shift work and is associated with increased risk of hypertension, stroke, obesity, diabetes, and cancer. These responses are linked to the proliferation of leukocytes in shift workers, suggesting a systemic signal as a potential mediator. The purpose of this study was to assess the relationship between systemic inflammation, leukocyte counts, and systemic endotoxemia in samples from a diverse cohort of day workers and shift workers. Participants (normothermic and normotensive) were healthy volunteers, non-smoking, and drug- and medication-free. The following outcomes were measured: C-reactive protein, TNF-α, IL-6, IL-1β, IL-10, leukocyte counts (monocytes, lymphocytes, and neutrophils), and lipopolysaccharide-binding protein (LBP). Risk factors that increase systemic inflammation, such as blood pressure, sleep loss, and cortisol, were also assessed. The results indicated that shift workers slept significantly less than day workers and had significantly increased concentrations of all of the cytokines measured as well as plasma cortisol. Regression models found that after controlling for covariates, shift-work exposure predicted the significant increase observed in IL-10, leukocyte counts, and LBP. Our results suggest that acute increases in low-grade systemic endotoxemia are unresolved during chronic shift-work exposure. This ongoing immune challenge may underlie the disrupted inflammatory responses characteristic of shift-work-related pathologies. Systemic endotoxemia may represent a novel target to investigate the early effects of exposure to shift-work schedules.

Impact of the Age of Cecal Material Transfer Donors on Alzheimer’s Disease Pathology in 5xFAD Mice

Alzheimer’s disease is a progressive neurodegenerative disorder affecting around 30 million patients worldwide. The predominant sporadic variant remains enigmatic as the underlying cause has still not been identified. Since efficient therapeutic treatments are still lacking, the microbiome and its manipulation have been considered as a new, innovative approach. 5xFAD Alzheimer’s disease model mice were subjected to one-time fecal material transfer after antibiotics-treatment using two types of inoculation: material derived from the caecum of age-matched (young) wild type mice or from middle aged, 1 year old (old) wild type mice. Mice were profiled after transfer for physiological parameters, microbiome, behavioral tasks, and amyloid deposition. A single time transfer of cecal material from the older donor group established an aged phenotype in the recipient animals as indicated by elevated cultivatable fecal Enterobacteriaceae and Lactobacillaceae representative bacteria, a decreased Firmicutes amount as assessed by qPCR, and by increased levels of serum LPS binding protein. While behavioral deficits were not accelerated, single brain regions (prefrontal cortex and dentate gyrus) showed higher plaque load after transfer of material from older animals. We could demonstrate that the age of the donor of cecal material might affect early pathological hallmarks of Alzheimer’s disease. This could be relevant when considering new microbiome-based therapies for this devastating disorder.

An Observational Study to Evaluate the Association between Intestinal Permeability, Leaky Gut Related Markers, and Metabolic Health in Healthy Adults

We explored whether metabolic health is linked to intestinal permeability, using a multi-sugar (MS) permeability test, and whether intestinal permeability is correlated with the leaky gut-related markers (LGM) zonulin, LBP, and sCD14. Metabolically healthy (n = 15) and unhealthy subjects (n = 15) were recruited based on waist circumference, fasting glucose, and high-density lipoprotein cholesterol levels. Participants underwent an MS permeability test that assessed site-specific permeabilities of the gastroduodenum and small and large intestines. The test was performed with/without an acetylsalicylic acid challenge to measure and correlate the gut permeability, LGM, and metabolic health. At baseline, metabolic health showed no correlation with gut permeability. Significant correlations were found between the metabolic health parameters and LGM. In the acetylsalicylic acid challenged MS permeability test, low-density lipoprotein cholesterol was correlated with the sucralose/erythritol ratio, reflecting the whole intestinal permeability. Correlations between most metabolic health parameters and LGM during the acetylsalicylic acid challenge were less pronounced than at baseline. In both MS permeability tests, no significant correlations were found between LGM (plasma and serum) and gut permeability. Thus, correlations between LGM and metabolic health might not be linked with paracellular gut permeability. Transcellular translocation and/or lipoprotein-related transportation is a more likely mechanism underlying the association between LGM and metabolic health.

Determinants and Reference Ranges of Serum Immunoglobulins in Middle-Aged and Elderly Individuals: a Population-Based Study

Purpose

In clinical practice, currently one reference range for serum immunoglobulin (Ig) A, G, and M is applied to all adults, although various factors may influence Ig serum levels. Population-based data on determinants of IgA, IgG, and IgM and recommendations for subgroup specific reference ranges are lacking. We aimed to provide an overview of determinants of IgA, IgG, and IgM in community-dwelling middle-aged and elderly individuals and explore determinants that influence Ig reference ranges.

Methods

Within the Rotterdam Study, we performed linear regression analyses for the association of demographic, lifestyle, and cardiovascular factors with serum IgA, IgG, and IgM. We furthermore calculated Ig reference ranges (based on percentiles), both overall and within relevant subgroups.

Results

We included 8768 participants (median age 62 years). IgA and IgG increased non-linearly with higher age (P < .0001 for both). Women had lower IgA (beta: − 0.24; 95% confidence interval [95% CI]: − 0.29; − 0.20) and IgG (beta: − 0.33; 95% CI: − 0.44; − 0.23), but higher IgM levels (beta: 0.08; 95% CI: 0.04;0.13) than men. Former and particularly current smoking were associated with lower IgA and IgG (betas between − 0.07 and − 1.03). Higher alcohol consumption was associated with lower IgG (beta for heavy drinking: − 0.70; 95% CI: − 0.91; − 0.48). Corticosteroid use was associated with lower IgG (beta: − 1.12; 95% CI: − 1.58; − 0.66). Associations with cardiovascular factors were heterogeneous and differed between sexes.

Conclusion

Age, sex, smoking, alcohol consumption, corticosteroid use, and cardiovascular factors are determinants that should be considered when interpreting serum Ig levels in middle-aged and elderly individuals and may require adjusted reference ranges.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10875-021-01120-5.

The Importance of Food for Endotoxemia and an Inflammatory Response

Bacterial endotoxin is a potent inflammatory antigen abundant in the human intestine. Endotoxins circulate in the blood at low concentrations in all healthy individuals. Elevated levels of circulatory endotoxins may cause inflammation with the development of chronic disease, either affecting metabolism, neurological disease, or resistance to viral and bacterial infections. The most important endotoxin is LPS, being a superantigen. In this narrative review, the effect of various food components to postprandially elevate circulating LPS and inflammatory markers is described. There is evidence that the intake of food enriched in fat, in particular saturated fat, may elevate LPS and pro-inflammatory markers. This occurs in both normal-weight and obese subjects. In obese subjects, inflammatory markers are already elevated before meal consumption. The importance of food choice for endotoxemia and inflammatory response is discussed.

Daily apple consumption reduces plasma and peripheral blood mononuclear cell-secreted inflammatory biomarkers in adults with overweight and obesity: a 6-week randomized, controlled, parallel-arm trial

BACKGROUND

Obesity-associated low-grade inflammation contributes to the development of cardiovascular disease (CVD). Apples are rich in anti-inflammatory bioactives including polyphenols and fiber.

OBJECTIVES

We aimed to determine the effects of regular apple consumption on fasting plasma biomarkers of inflammation (primary outcome), endotoxemia, carbohydrate and lipid metabolism (glucose, insulin, triacylglycerol; secondary outcomes), and peripheral blood mononuclear cell (PBMC)-secreted cytokines (secondary outcome) in individuals with overweight and obesity.

METHODS

A randomized, controlled, parallel-arm trial was conducted with n = 46 participants. After avoiding foods and beverages rich in polyphenols and fiber for 2 wk, participants consumed 3 whole Gala apples (∼200 g edible parts)/d as part of their habitual diet (n = 23) or avoided apples (control, n = 23) for 6 wk. All participants limited consumption of polyphenols and fiber during the 6-wk trial. Fasting blood samples were collected before and after 6 wk for analysis of plasma biomarkers and isolation of PBMCs, which were cultured for 24 h unstimulated or stimulated with LPS (10 ng/mL).

RESULTS

Forty-four participants completed the trial (30 female, 14 male; mean ± SEM age: 45.4 ± 2.2 y; BMI: 33.4 ± 0.9 kg/m2). After ANCOVA and correcting for multiple comparisons, apples decreased fasting plasma C-reactive protein by 17.0% (range: 14.3%-19.6%, P = 0.005), IL-6 by 12.4% (range: 6.7%-17.5%, P < 0.001), and LPS-binding protein by 20.7% (range: 14.1%-26.4%, P < 0.001) compared with control. Apples also decreased PBMC-secreted IL-6 by 28.3% (range: 22.4%-33.5%, P < 0.001) and IL-17 by 11.0% (range 5.8-15.6%, P = 0.003) in the unstimulated condition compared with control. Exploratory analysis showed apples also increased plasma total antioxidant capacity by 9.6% (range: 1.7-18.9%, P = 0.002) compared with control. However, apples had no effect on anthropometric or other CVD risk markers.

CONCLUSIONS

Six-week daily whole Gala apple consumption may be an effective dietary strategy to mitigate the obesity-associated inflammation that exacerbates CVD risk, without weight loss. This trial was registered at clinicaltrials.gov as NCT03523403.

Gut Microbiome and Metabolome Profiles Associated with High-Fat Diet in Mice

Obesity can be caused by microbes producing metabolites; it is thus important to determine the correlation between gut microbes and metabolites. This study aimed to identify gut microbiota-metabolomic signatures that change with a high-fat diet and understand the underlying mechanisms. To investigate the profiles of the gut microbiota and metabolites that changed after a 60% fat diet for 8 weeks, 16S rRNA gene amplicon sequencing and gas chromatography-mass spectrometry (GC-MS)-based metabolomic analyses were performed. Mice belonging to the HFD group showed a significant decrease in the relative abundance of Bacteroidetes but an increase in the relative abundance of Firmicutes compared to the control group. The relative abundance of Firmicutes, such as Lactococcus, Blautia, Lachnoclostridium, Oscillibacter, Ruminiclostridium, Harryflintia, Lactobacillus, Oscillospira, and Erysipelatoclostridium, was significantly higher in the HFD group than in the control group. The increased relative abundance of Firmicutes in the HFD group was positively correlated with fecal ribose, hypoxanthine, fructose, glycolic acid, ornithine, serum inositol, tyrosine, and glycine. Metabolic pathways affected by a high fat diet on serum were involved in aminoacyl-tRNA biosynthesis, glycine, serine and threonine metabolism, cysteine and methionine metabolism, glyoxylate and dicarboxylate metabolism, and phenylalanine, tyrosine, and trypto-phan biosynthesis. This study provides insight into the dysbiosis of gut microbiota and metabolites altered by HFD and may help to understand the mechanisms underlying obesity mediated by gut microbiota.

Effects of Lipopolysaccharide-Binding Protein (LBP) Single Nucleotide Polymorphism (SNP) in Infections, Inflammatory Diseases, Metabolic Disorders and Cancers

Inflammation, which is induced by the immune response, is recognized as the driving factor in many diseases, including infections and inflammatory diseases, metabolic disorders and cancers. Genetic variations in pivotal genes associated with the immune response, particularly single nucleotide polymorphisms (SNPs), may account for predisposition and clinical outcome of diseases. Lipopolysaccharide (LPS)-binding protein (LBP) functions as an enhancer of the host response to LPS, the main component of the outer membrane of gram-native bacteria. Given the crucial role of LBP in inflammation, we will review the impact of SNPs in the LBP gene on infections and inflammatory diseases, metabolic disorders and cancers.

Characterizing the Effects of Calcium and Prebiotic Fiber on Human Gut Microbiota Composition and Function Using a Randomized Crossover Design-A Feasibility Study

Consumption of prebiotic inulin has been found to increase calcium absorption, which may protect against gut diseases such as colorectal cancer. This dietary relation may be modulated by compositional changes in the gut microbiota; however, no human study has addressed this hypothesis. We determined the feasibility of a randomized crossover trial to evaluate the effect of three interventions (combined calcium and inulin supplementation, calcium supplementation alone, and inulin supplementation alone) on the intestinal microbiota composition and function. We conducted a 16-week pilot study in 12 healthy adults who consumed the three interventions in a random sequence. Participants provided fecal and blood samples before and after each intervention. Each intervention period lasted four weeks and was flanked by one-week washout periods. 16S ribosomal RNA sequencing and quantification of short chain fatty acids (SCFA) was determined in fecal samples. Systemic lipopolysaccharide binding protein (LBP) was quantified in serum. Of the 12 individuals assigned to an intervention sequence, seven completed the study. Reasons for dropout included time (n = 3), gastrointestinal discomfort (n = 1), and moving (n = 1). Overall, participants reported positive attitudes towards the protocol (n = 9) but were unsatisfied by the practicalities of supplement consumption (44%) and experienced digestive discomfort (56%). We found no appreciable differences in microbial composition, SCFA concentration, nor LBP concentrations when comparing intervention periods. In conclusion, an intervention study using a randomized crossover design with calcium and a prebiotic fiber is feasible. Improvements of our study design include using a lower dose prebiotic fiber supplement and a larger sample size.

Gut microbiome, prebiotics, intestinal permeability and diabetes complications

Diabetes is a metabolic condition. The composition of the gut microbiota is altered in diabetes with reduced levels of short chain fatty acids (SCFA) producers, notably butyrate. Butyrate is associated with a number of beneficial effects including promoting the integrity of the gastrointestinal barrier. Diabetes may lead to an increase in the permeability of the gut barrier, which is thought to contribute to systemic inflammation and worsen the microvascular complications of diabetes. Prebiotics, non-digestible carbohydrates, are fermented by the colonic microbiota leading to the production of a range of metabolites including SCFAs. Thus, prebiotics represent a dietary approach to increase levels of microbially produced SCFAs and improve intestinal permeability in diabetes. Whether prebiotics can lead to a reduction in the risk of developing diabetes complications in individuals with type 2 diabetes needs to be explored.

Identification of macrophage activation-related biomarkers in obese type 2 diabetes that may be indicative of enhanced respiratory risk in COVID-19

Hyperactivation of the immune system through obesity and diabetes may enhance infection severity complicated by Acute Respiratory Distress Syndrome (ARDS). The objective was to determine the circulatory biomarkers for macrophage activation at baseline and after serum glucose normalization in obese type 2 diabetes (OT2D) subjects. A case-controlled interventional pilot study in OT2D (n = 23) and control subjects (n = 23). OT2D subjects underwent hyperinsulinemic clamp to normalize serum glucose. Plasma macrophage-related proteins were determined using Slow Off-rate Modified Aptamer-scan plasma protein measurement at baseline (control and OT2D subjects) and after 1-h of insulin clamp (OT2D subjects only). Basal M1 macrophage activation was characterized by elevated levels of M1 macrophage-specific surface proteins, CD80 and CD38, and cytokines or chemokines (CXCL1, CXCL5, RANTES) released by activated M1 macrophages. Two potent M1 macrophage activation markers, CXCL9 and CXCL10, were decreased in OT2D. Activated M2 macrophages were characterized by elevated levels of plasma CD163, TFGβ-1, MMP7 and MMP9 in OT2D. Conventional mediators of both M1 and M2 macrophage activation markers (IFN-γ, IL-4, IL-13) were not altered. No changes were observed in plasma levels of M1/M2 macrophage activation markers in OT2D in response to acute normalization of glycemia. In the basal state, macrophage activation markers are elevated, and these reflect the expression of circulatory cytokines, chemokines, growth factors and matrix metalloproteinases in obese individuals with type 2 diabetes, that were not changed by glucose normalisation. These differences could potentially predispose diabetic individuals to increased infection severity complicated by ARDS.

Clinical trial reg. no: NCT03102801; registration date April 6, 2017.

Plasma Lipopolysaccharide-Binding Protein Reflects Risk and Progression of Parkinson's Disease

BACKGROUND

Lipopolysaccharide-binding protein (LBP) presents bacterial endotoxin, lipopolysaccharides, to cellular surface pattern receptors for immune responses in the gut-brain axis of Parkinson's disease (PD).

OBJECTIVE

We investigated whether plasma LBP levels were associated with PD severity and progression.

METHODS

This study included 397 participants (248 PD patients and 149 controls). We measured participants' plasma levels of LBP and pro-inflammatory cytokines, including TNF-α, IL-6, andIL-17A. PD patients underwent motor and cognition evaluations at baseline and at a mean follow-up interval of 4.7±2.3 years. We assessed the progression of motor and cognition symptoms based on changes in the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III motor score and Mini-Mental State Examination (MMSE) score, respectively.

RESULTS

Plasma LBP levels were lower in PD patients than controls (9.08±2.91 vs. 10.10±3.00μg/ml, p < 0.01). A multiple logistic regression model with adjustment for age, sex, and plasma cytokine levels revealed that reduced plasma LBP levels were associated with increased PD risk (odds ratio 0.816, [95% CI 0.717-0.929], p = 0.002). Among PD patients, LBP levels were correlated with MDS-UPDRS part III motor score after adjustment for confounders (coefficient = 0.636, p = 0.017), but not with MMSE score. Adjusted Cox regression analysis showed that higher plasma LBP levels associated with faster motor progression (adjusted hazard ratio 1.084 [95% CI 1.011-1.163], p = 0.024) during follow-up.

CONCLUSION

Our results demonstrated that plasma LBP levels reflect risk, motor symptom severity and progression in patients with PD.

Effects of Supplemental Calcium and Vitamin D on Circulating Biomarkers of Gut Barrier Function in Patients with Colon Adenoma: A Randomized Clinical Trial

Gut barrier dysfunction promotes chronic inflammation, contributing to several gastrointestinal diseases, including colorectal cancer. Preliminary evidence suggests that vitamin D and calcium could prevent colorectal carcinogenesis, in part, by influencing gut barrier function. However, relevant human data are scarce. We tested the effects of supplemental calcium (1,200 mg/day) and/or vitamin D3 (1,000 IU/day) on circulating concentrations of biomarkers of gut permeability (anti-flagellin and anti-lipopolysaccharide IgA and IgG, measured via ELISA) from baseline to 1 and 3 or 5 years postbaseline among 175 patients with colorectal adenoma in a randomized, double-blinded, placebo-controlled clinical trial. We also assessed factors associated with baseline concentrations of these biomarkers. We found no appreciable effects of supplemental vitamin D3 and/or calcium on individual or aggregate biomarkers of gut permeability. At baseline, a combined permeability score (the summed concentrations of all four biomarkers) was 14% lower among women (P = 0.01) and 10% higher among those who consumed >1 serving per day of red or processed meats relative to those who consumed none (P trend = 0.03). The permeability score was estimated to be 49% higher among participants with a body mass index (BMI) > 35 kg/m2 relative to those with a BMI < 22.5 kg/m2 (P trend = 0.17). Our results suggest that daily supplemental vitamin D3 and/or calcium may not modify circulating concentrations of gut permeability biomarkers within 1 or 3-5 years, but support continued investigation of modifiable factors, such as diet and excess adiposity, that could affect gut permeability. PREVENTION RELEVANCE: Calcium and vitamin D may be involved in regulating and maintaining the integrity of the intestinal mucosal barrier, the dysfunction of which results in exposure of the host to luminal bacteria, endotoxins, and antigens leading to potentially cancer-promoting endotoxemia and chronic colon inflammation. While our results suggest that daily supplementation with these chemopreventive agents does not modify circulating concentrations of gut permeability biomarkers, they support continued investigation of other potential modifiable factors, such as diet and excess adiposity, that could alter gut barrier function, to inform the development of treatable biomarkers of risk for colorectal neoplasms and effective colon cancer preventive strategies.

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.

Identifying a biological signature of prenatal maternal stress

Psychological stress affects maternal gastrointestinal (GI) permeability, leading to low-grade inflammation, which can negatively affect fetal development. We investigated a panel of circulating markers as a biological signature of this stress exposure in pregnant women with and without the stress-related GI disorder irritable bowel syndrome (IBS). Markers of GI permeability and inflammation were measured in plasma from healthy and IBS cohorts of women at 15 and 20 weeks’ gestation. Biomarkers were evaluated with respect to their degree of association to levels of stress, anxiety, and depression as indicated by responses from the Perceived Stress Scale, State-Trait Anxiety Inventory, and Edinburgh Postnatal Depression Scale. High levels of stress were associated with elevations of soluble CD14, lipopolysaccharide binding protein (LBP), and tumor necrosis factor–α, while anxiety was associated with elevated concentrations of C-reactive protein (CRP) in otherwise healthy pregnancies. Prenatal depression was associated with higher levels of soluble CD14, LBP, and CRP in the healthy cohort. High levels of prenatal anxiety and depression were also associated with lower concentrations of tryptophan and kynurenine, respectively, in the IBS cohort. These markers may represent a core maternal biological signature of active prenatal stress, which can be used to inform intervention strategies via stress reduction techniques or other lifestyle approaches. Such interventions may need to be tailored to reflect underlying GI conditions, such as IBS.

Biomarkers of cardiometabolic complications in survivors of childhood acute lymphoblastic leukemia

Survivors of childhood acute lymphoblastic leukemia (cALL) are at higher risk of developing cardiometabolic complications. We aimed at exploring the associations between biomarkers of inflammation, oxidative stress, endothelial function, endotoxemia and cardiometabolic risk factors. We conducted a cross-sectional analysis in 246 cALL survivors (mean age, 22.1 ± 6.3 years; mean time since diagnosis, 15.5 ± 5.2 years) and evaluated the associations using a series of logistic regressions. Using structural equation models, we also tested if the relationship between endotoxemia and cardiometabolic complications was mediated by the latent (unobserved) variable inflammation inferred from the observed biomarkers CRP, TNF-α and IL-6. High leptin-adiponectin ratio was associated with obesity [adjusted OR = 15.7; 95% CI (6.2–39.7)], insulin resistance [20.6 (5.2–82.1)] and the metabolic syndrome [11.2 (2.6–48.7)]. Higher levels of plasminogen activator inhibitor-1 and tumor necrosis factor-α were associated with obesity [3.37 (1.6–7.1) and 2.34 (1.3–4.2), respectively] whereas high C-reactive protein levels were associated with insulin resistance [3.3 (1.6–6.8)], dyslipidemia [2.6 (1.4–4.9)] and MetS [6.5 (2.4–17.9)]. Our analyses provided evidence for a directional relationship between lipopolysaccharide binding protein, related to metabolic endotoxemia, inflammation and cardiometabolic outcomes. Identification of biomarkers and biological mechanisms could open new avenues for prevention strategies to minimize the long-term sequelae, improve follow-up and optimize the quality of life of this high-risk population.

Endotoxemia coupled with heightened inflammation predicts future depressive symptoms

OBJECTIVE

Cross-sectional data have linked gut barrier abnormalities and endotoxemia with depression, even among those without gastrointestinal symptoms. This study examined longitudinal associations between endotoxemia markers and depressive symptoms, as well as the role of inflammation in this relationship.

DESIGN

At three annual visits, 315 women (n=209 breast cancer survivors, n = 106 non-cancer patient controls, M=55 years old) completed the Center for Epidemiological Studies Depression questionnaire (CES-D) and provided blood samples to assess inflammatory markers - interleukin-6, tumor necrosis factor-alpha, and C-reactive protein - and endotoxemia markers - lipopolysaccharide-binding protein (LBP), soluble CD14 (sCD14), and their ratio.

RESULTS

Adjusting for key demographic variables, health behaviors, visit 1 depressive symptoms, and cancer status and treatment, women with higher visit 1 LBP and LBP/sCD14 had more depressive symptoms at the two subsequent annual visits. Illustrating the notable impact, a woman at the 75th percentile for LBP or LBP/sCD14 at visit 1 was 18 % more likely to report clinically significant depressive symptoms (CES-D ≥16) at follow-up than a woman in the lowest quartile. Cancer status and treatment type did not modulate this relationship. In contrast, visit 1 depressive symptoms did not predict endotoxemia at follow-up. A significant interaction between LBP/sCD14 and inflammatory burden suggested that visit 1 endotoxemia fueled depressive symptoms only in the context of elevated inflammation.

CONCLUSION

These results suggest that endotoxemia, combined with systemic inflammation, can drive depressive symptoms. These findings may implicate bacterial endotoxin translocation from the gut to the bloodstream in depression etiology. Interventions that reduce endotoxemia and inflammation may lessen the risk of depression.