Exploring the causal link between circulating cytokines and sarcopenia traits: A Mendelian randomization analysis

BACKGROUND

Previous observational studies have linked circulating cytokines to sarcopenia, but their causal relationship remains unclear. This study employed Mendelian Randomization (MR) to investigate the causal links between circulating cytokines and sarcopenia-related traits using genetic data.

METHODS

A two-sample bidirectional MR analysis was conducted using data from individuals of European ancestry, utilizing genome-wide association studies (GWAS) statistics. The study selected instrumental single nucleotide polymorphisms (SNPs) significantly associated with circulating cytokines and applied multiple MR methods, including inverse variance weighted (IVW), Weighted Median, MR-Egger, Weighted Mode, Simple Mode, and MR-PRESSO. The traits analyzed were appendicular lean mass (ALM) and grip strength. Heterogeneity, robustness, and consistency of results were assessed using Cochran's Q statistic, MR-Egger regression, and "leave-one-out" sensitivity analyses.

RESULTS

The IVM-MR analysis showed a casual association between genetically predicted circulating levels of interleukin-16 and both ALM and grip strength (ALM: OR = 0.990, 95% CI: 0.980-1.000, p = .049; grip strength: OR = 0.971, 95% CI: 0.948-0.995, p = .020). Additionally, interferon-gamma-induced protein 10 (IP-10), interleukin-1-beta (IL-1β), and hepatocyte growth factor (HGF) were correlated with ALM and vascular endothelial growth factor (VEGF), interleukin-12 (IL-12), and interleukin-5 (IL-5) with grip strength. Comparable results were confirmed via the MR-Egger, Weighted Median, Weighted Mode, and Simple Mode methods. Sensitivity analysis showed no horizontal pleiotropy to bias the causal estimates.

CONCLUSION

The results suggest a significant causal effect of inflammatory cytokines on sarcopenia, offering new avenues for therapeutic target development. However, the study's focus on a European ancestry cohort limits its generalizability to other populations. Future research should aim to include diverse ethnic groups to validate and broaden these findings, thereby enhancing our understanding of sarcopenia's mechanisms in a global context.

The causal association between circulating cytokines with the risk of frailty and sarcopenia under the perspective of geroscience

Introduction

Circulating cytokines were considered to play a critical role in the initiation and propagation of sarcopenia and frailty from observational studies. This study aimed to find the casual association between circulating cytokines and sarcopenia and frailty from a genetic perspective by two-sample Mendelian randomization (MR) analysis.

Methods

Data for 41 circulating cytokines were extracted from the genome-wide association study dataset of 8,293 European participants. Inverse-variance weighted (IVW) method, MR-Egger, and weighted median method were applied to assess the relationship of circulating cytokines with the risk of aging-related syndromes and frailty. Furthermore, MR-Egger regression was used to indicate the directional pleiotropy, and Cochran's Q test was used to verify the potential heterogeneity. The "leave-one-out" method was applied to visualize whether there was a causal relationship affected by only one anomalous single-nucleotide polymorphisms.

Results

Genetic predisposition to increasing levels of interleukin-10 (IL-10), IL-12, and vascular endothelial growth factor (VEGF) was associated with the higher risk of low hand grip strength according to the IVW method [R = 1.05, 95% CI = 1.01-1.10, P = 0.028, false discovery rate (FDR)-adjusted P = 1.000; OR = 1.03, 95% CI = 1.00-1.07, P = 0.042, FDR-adjusted P = 0.784; OR = 1.02, 95% CI = 1.00-1.05, P = 0.038, FDR-adjusted P = 0.567]. Furthermore, genetically determined higher macrophage colony-stimulating factors (M-CSFs) were associated with a lower presence of appendicular lean mass (OR = 1.01, 95% CI = 1.00-1.02, P = 0.003, FDR-adjusted P = 0.103). Monokine induced by interferon-γ (MIG) and tumor necrosis factor-beta (TNF-β) were associated with a higher risk of frailty (OR = 1.03, 95% CI = 1.01-1.05, P < 0.0001, FDR-adjusted P = 0.012; OR = 1.01, 95% CI = 1.00-1.03, P = 0.013, FDR-adjusted P = 0.259). In this study, we did not find heterogeneity and horizontal pleiotropy between the circulating cytokines and the risk of frailty and sarcopenia.

Conclusion

Genetic predisposition to assess IL-10, IL-12, and VEGF levels was associated with a higher risk of low hand grip strength and M-CSF with the presence of appendicular lean mass. The high levels of TNF-β and MIG were associated with a higher risk of frailty. More studies will be required to explore the molecular biological mechanisms underlying the action of inflammatory factors.

Causal associations between circulating cytokines and risk of sepsis and related outcomes: a two-sample Mendelian randomization study

Introduction

Sepsis represents a critical medical condition that arises due to an imbalanced host reaction to infection. Central to its pathophysiology are cytokines. However, observational investigations that explore the interrelationships between circulating cytokines and susceptibility to sepsis frequently encounter challenges pertaining to confounding variables and reverse causality.

Methods

To elucidate the potential causal impact of cytokines on the risk of sepsis, we conducted two-sample Mendelian randomization (MR) analyses. Genetic instruments tied to circulating cytokine concentrations were sourced from genome-wide association studies encompassing 8,293 Finnish participants. We then evaluated their links with sepsis and related outcomes using summary-level data acquired from the UK Biobank, a vast multicenter cohort study involving over 500,000 European participants. Specifically, our data spanned 11,643 sepsis cases and 474,841 controls, with subsets including specific age groups, 28-day mortality, and ICU-related outcomes.

Results and Discussion

MR insights intimated that reduced genetically-predicted interleukin-10 (IL-10) levels causally correlated with a heightened sepsis risk (odds ratio [OR] 0.68, 95% confidence interval [CI] 0.52-0.90, P=0.006). An inverse relationship emerged between monocyte chemoattractant protein-1 (MCP-1) and sepsis-induced mortality. Conversely, elevated macrophage inflammatory protein 1 beta (MIP1B) concentrations were positively linked with both sepsis incidence and associated mortality. These revelations underscore the causal impact of certain circulating cytokines on sepsis susceptibility and its prognosis, hinting at the therapeutic potential of modulating these cytokine levels. Additional research is essential to corroborate these connections.

Circulating cytokines and alcoholic liver disease: a two-sample bidirectional Mendelian randomization study

BACKGROUND

Increased inflammation in the liver during ethanol exposure is a major feature of alcoholic liver disease (ALD). An important contributing component to the development of ALD is the inflammatory response brought on by immunological response, however the connection between individual circulating cytokines and ALD is still unclear. To ascertain the causation, we conducted a two-sample bidirectional Mendelian randomization research.

METHODS

We extracted 41 cytokines and growth factors of 8293 Europeans and ALD cases of the same ethnicity (1416 cases and 217,376 controls) from the Genome-Wide Association Studies (GWAS) database for two-sample bidirectional MR analysis.

RESULTS

Our analyses suggest that higher interleukin-7 (IL-7) levels are associated with an increased risk of ALD (p = 0.028, OR = 1.191,95% CI = 1.019-1.392), while tumor necrosis factor related apoptosis inducing ligand (TRAIL) is a protective factor for ALD (p = 0.032, OR = 0.863, 95% CI = 0.754-0.988) which can reduce the risk of disease occurrence. In addition, genetically predicted ALD does not affect the expression of circulating cytokines regulators.

CONCLUSIONS

Our study supports that cytokines play a pivotal role in the pathogenesis of ALD. To determine the mechanisms and pathways of action of these biomarkers, further basic research is required to ensure their clinical suitability for preventing and treating ALD.

Genetically predicted levels of circulating cytokines and the risk of six immune skin diseases: a two-sample Mendelian randomization study

Background

Circulating cytokines play a crucial role in the onset and progression of immune skin diseases. However, the causal relationships and the direction of causal effects require further investigation.

Methods

Two-sample Mendelian randomization (MR) analyses were conducted to assess the causal relationships between 41 circulating cytokines and six immune skin diseases including alopecia areata, chloasma, hidradenitis suppurativa (HS), lichen planus (LP), seborrheic dermatitis, and urticaria, using summary statistics from genome-wide association studies. Reverse MR analyses was performed to test for the reverse causation. Pleiotropy and heterogeneity tests were conducted to assess the robustness of the findings.

Results

Twelve unique cytokines showed a suggestive causal relationship with the risk of six immune skin diseases. Among them, the causal effects between 9 unique cytokines and immune skin diseases have strong statistical power. Additionally, the concentrations of six cytokines might be influenced by LP and urticaria. After Bonferroni correction, the following associations remained significant: the causal effect of beta-nerve growth factor on HS (odds ratio [OR] = 1.634, 95% confidence interval [CI] = 1.226-2.177, p = 7.97e-04), interleukin (IL)-6 on LP (OR = 0.615, 95% CI = 0.481-0.786, p = 1.04e-04), IL-4 on LP (OR = 1.099. 95% CI = 1.020-1.184, p = 1.26e-02), and IL-2 on urticaria (OR = 0.712, 95% CI = 0.531-0.955, p = 2.33e-02).

Conclusion

This study provides novel perspectives on the relationship between circulating cytokines and immune skin diseases, potentially providing valuable insights into their etiology, diagnostic approaches, and treatment.

Serum Cytokine and miRNA Levels Are Differently Expressed in Right- and Left-Sided Colon Cancer

The tumor location in colorectal cancer (right- or left-sided colon cancer) is a key factor in determining disease progression. Right- and left-sided colon tumors are different in their clinical and molecular characteristics. Dysregulation of serum levels of proinflammatory cytokines, such as Transforming Growth Factor β (TGF-β) and Tumor Necrosis Factor-α (TNF-α), and Peroxisome Proliferator Activated Receptor-γ (PPAR-γ), known to be a growth-limiting and differentiation-promoting factor, as well as changes in miRNAs expression, are the major signaling pathways involved in the pathogenesis of this neoplasia. In the serum from 60 colorectal cancer (CRC) patients, we compared the differences in the expression of the levels of TGF-β, TNF-α, and PPAR-γ and in the expression of the main human miRNAs between right and left CRC. A significant over-expression in the TGF-β and TNF-α levels was observed in the serum from right-sided colon cancer patients. For the PPAR-γ, the patients with CRC located on the right-side showed lower levels than those detected in the serum from left-sided CRC subjects. Furthermore, significant differences also existed in the expression of specific circulating miRNAs between right- and left-sided CRC. In particular, the right upregulated miRNAs were all involved in the cell growth and proliferation related pathways. These findings confirm that the analysis of circulating levels of TGF-β, TNF-α, and PPAR-γ, as well as the study of the specific miRNAs in the serum, are able to identify specific characteristics of CRC patients, useful for choosing a personalized treatment protocol.

Circulating levels of cytokines and risk of cardiovascular disease: a Mendelian randomization study

Background

Epidemiological studies have linked various circulating cytokines to cardiovascular disease (CVD), which however remains uncertain whether these relationships represent causality or are due to bias. To address this question, we conducted a Mendelian randomization (MR) analysis to systematically investigate the causal effects of circulating cytokine levels on CVD development.

Methods

This study leveraged the summary statistic from respective genome-wide association study (GWAS) of 47 cytokines and four types of CVD. The cis-quantitative trait locus (cis-QTL) definition, derived from a GWAS meta-analysis comprising 31,112 participants of European descent, served as instruments for cytokines. A two-sample MR design was employed, followed by comprehensive sensitivity analyses to validate the robustness of results.

Results

The results of inverse-variance weighted method using cis-protein QTL (cis-pQTL) instruments, showed the causal effects of four cytokines (i.e., IL-1ra, MCSF, SeSelectin, SCF) on the risk of coronary artery disease (CAD). We also identified causal relationships between two cytokines (i.e., IL-2ra, IP-10) and heart failure (HF), as well as two cytokines (i.e., MCP-3, SeSelectin) and atrial fibrillation (AF), after controlling for false discovery rate (FDR). The use of cis-expression QTL (cis-eQTL) revealed additional causal associations between IL-1a, MIF and CAD, between IL-6, MIF, and HF, as well as between FGFBasic and AF. No significant sign was survived for stroke with FDR applied. Results were largely consistent across sensitivity analyses.

Conclusion

The present study provides supportive evidence that genetic predisposition to levels of certain cytokines causally affects the development of specific type of CVD. These findings have important implications for the creation of novel therapeutic strategies targeting these cytokines as a means of preventing and treating CVD.

Early Detection of Therapeutic Benefit from PD-1/PD-L1 Blockade in Advanced Lung Cancer by Monitoring Cachexia-Related Circulating Cytokines

Cancer cachexia is associated with poor immunotherapeutic outcomes. This prospective observational study longitudinally evaluated the role of cachexia-related circulating cytokines in predicting the risk and benefit of PD-1/PD-L1 blockade in advanced lung cancer. Forty-one circulating cytokines at baseline and after one cycle of PD-1/PD-L1 blockade treatment were measured in patients with advanced lung cancer between 2019 and 2020. The cachexia-related cytokines were identified by comparing the levels of circulating cytokines between cachectic and non-cachectic patients. Among 55 patients, 49.1% were diagnosed with cachexia at the beginning of PD-1/PD-L1 blockade therapy. Baseline levels of the circulating cytokines IL-6, IL-8, IL-10, IL-15, and IP-10 were significantly higher in cachectic patients. In contrast, the level of eotaxin-1 was lower in cachectic patients than in those without cachexia. Higher IL-6 at baseline and during treatment was associated with a greater risk of immune-related adverse events, while higher IL-10 at baseline was linked to worse overall survival. More importantly, increased eotaxin-1 after one cycle of PD-1/PD-L1 blockade treatment was associated with higher objective response and better overall survival. A blood-based, cachexia-related cytokine assay may yield potential biomarkers for the early prediction of clinical response to PD-1/PD-L1 blockade and provide clues for improving the outcomes of cachectic patients.

Case Report: A Squamous Cell Lung Carcinoma Patient Who Responded to Neoadjuvant Immunochemotherapy but Died From Anastomosis Leakage or/and irAEs: Immune Microenvironment and Genomic Features Changes

Clinical trials indicated that PD-1/PD-L1 inhibitors significantly improve the survival rate of patients with advanced non-small cell lung cancer (NSCLC) and induce immune-related adverse events (irAEs). Thus, the molecular and immune characteristics during PD-1/PD-L1 inhibitor therapy are worth investigating further. We report the case of a 62-year-old male patient diagnosed with stage IIIA squamous cell lung carcinoma (SQCC) who responded to neoadjuvant and adjuvant nivolumab combined chemotherapy but died from anastomosis leakage or/and irAEs. In the pretreatment tumor biopsy, PD-L1 expression was negative and a few T cells, NK cells, and macrophages had infiltrated the tumor. Wild-type EGFR/STK11, mutant TP53, microsatellite stability, and low tumor mutational burden were also found at baseline. After neoadjuvant immunochemotherapy, the tumor was significantly reduced, PD-L1 expression levels were increased by 50%, and more CD8⁺ and CD8⁺ PD-1⁺ T cells had infiltrated the resected tumor tissue. Immune-related lung injury occurred during adjuvant immunochemotherapy, and serum levels of C-reactive protein, IL-13, IL-4, eotaxin, VEGF-A, IL-8, and IFN-gamma were increased. This case demonstrates a squamous cell lung carcinoma patient who responded to neoadjuvant immunochemotherapy that reshaped the tumor immune environment from “cold” to “hot.” Unfortunately, the patient eventually died from anastomosis leakage or/and irAEs during adjuvant immunochemotherapy.

Trehalose enhances bone fracture healing in a rat sleep deprivation model

Background

The purpose of this study was to investigate whether sleep deprivation (SD) could delay bone fracture healing and evaluate the therapeutic effect of trehalose.

Methods

Eighteen 300-350 g female Sprague-Dawley rats were created a mid-femoral transverse osteotomy in the right thigh and divided into three groups (i.e., group 1: fracture; group 2: fracture + SD; and group 3: fracture + SD + trehalose). Seven days after surgery, the rats in group 2 and group 3 were started to get sleep-deprived for 18 h per day for 3 weeks. The rats in group 3 were injected with trehalose intraperitoneally at 1 g/kg/d for 3 weeks. Radiological and histological analyses were used to assess fracture healing quality. Circulating cytokines were detected by the end of the study. The expression of M1 and M2 macrophage markers were measured by quantitative real-time polymerase chain reaction (qPCR).

Results

X-rays showed group 2 experienced much poorer fracture healing. Micro CT demonstrated that the bone quality of the fracture callus site in group 2 was much worse than that in groups 1 and 3. Both haematoxylin eosin (H&E) and Masson staining revealed that the bone fracture of the group 2 healed worse. Elisa results demonstrated that the interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) of the rats in group 2 were significantly higher. In vitro study showed that 100 mM trehalose enhanced the expression of M2 macrophage markers (Arg-1 and IL-10), and decreased M1 macrophage polarization through the decreasing expression of IL-6.

Conclusions

The present study showed (SD) could delay bone fracture healing in a rat model. And, trehalose could promote the healing of delayed bone fracture union by down-regulating pro-inflammatory mediators and enhancing M2 polarization.

Postoperative course and prognostic value of circulating angiogenic cytokines after pancreatic cancer resection

Background

Circulating angiogenic cytokines (CACs) have been confirmed as prognostic biomarkers and therapeutic targets in several solid tumors. However, their role as prognostic biomarkers in resected pancreatic ductal adenocarcinoma (PDAC) is unknown.

Results

The expression of CACs in patients with PDAC differs from those with CP both pre- and postoperatively. Correlation analyses show significant correlations between circulating levels of CACs: VEGF was correlated with IL-6 (r = 0.457), FGF (r = 0.44), G-CSF (r = 0.543), HGF (r = 0.586) and SDF-1α (r = 0.784) before the surgery. The circulating levels of TNF-α correlated with the serum concentration of IL-4 before (r= 0.656) and after the resection (r = 0.776 on POD 3, r = 0.865 on POD 7). Gender did not show any correlation with serum levels of CAC, except for significantly higher levels of EGF in males (P = 0.002). Other clinicopathological variables such as age (< 65 vs. > 65 years), T, N, or UICC stage did not have an association with the cytokine levels. The multivariate model including the entire angiogenic panel revealed that postoperative increasing levels of EGF (P = 0.023), PDGFA-A (P = 0.024), TNF-α (P = 0.001) and IL-8 (P = 0.049) were associated with a favorable prognosis, whereas elevating levels of VEGF (P = 0.005) correlated with a poor cancer-specific survival.

Materials and Methods

Preoperative and postoperative blood samples were collected in patients undergoing surgery for PDAC (n = 40) or chronic pancreatitis (CP; n = 9). Serum levels of 13 angiogenic cytokines (IL-4, IL-6, FGF-b, G-CSF, TNF-α, VEGF, HGF, SDF-1α, IL-8, EGF, Ang-1, PDGF-AA and PlGF) were analyzed using ELISA and Multiplex. Prognostic factors were identified by a Cox proportional hazards model.

Conclusions

Postoperative changes of serum levels of certain angiogenic cytokines correlate with patients’ prognosis after resection for pancreatic cancer. CACs should thus be considered as biomarkers in patients with resected pancreatic cancer.

Cytokines in the blood and semen of infertile patients

Cytokines have been important mediators of the immunity and can be involved in numerous processes in the male genital tract including acting as immunomodulatory elements within the male gonad.

The aims of this study were: 1) to detect pro- and anti-inflammatory cytokine levels in the control group and subgroups of infertile men; and 2) to set up the practical recommendations concerning determination of cytokine levels for the male infertility diagnosis.

Observations were performed in a group of 82 men: healthy controls (n = 27) and infertile patients (n = 55). The male infertility group was further subdivided into patients with: varicocele (n = 22), idiopathic infertility (n = 13) and partners of couples with recurrent spontaneous abortion (RSA; n = 20). Semen analysis was determined following WHO criteria. The cytokine interleukin 1β (IL-1β), IL-6, IL-10, IL-18; tumor necrosis factor α (TNF-α), interferon g (IFN-g) and transforming growth factor β1 (TGF-β1) contents in serum and seminal plasma were determined by quantitative ELISA.

An interesting marker of male infertility appears to be TGF-β1 (blood) significantly elevated in idiopathically infertile males and in the RSA group. Besides elevated TGF-β1 in a group of idiopathic infertility significantly elevated IL-10, IL-18, IFN-g (blood) and statistically decreased IL-1β while increased IFN-g were revealed in seminal plasma compared to healthy controls.

We may postulate novel cytokine micropatterns for patients with different background of infertility. Therefore, circulating cytokines: IL-1β, IL-10, IL-18, TGF-β1, IFN-g and IL-1β, IFN-g and TGF-β1 in seminal plasma should be extended in evaluation of specific types of male infertility.

Temporal relationships between adipocytokines and diabetes risk in Hispanic adolescents with obesity

OBJECTIVE

Circulating cytokines are frequently cited as contributors to insulin resistance in children with obesity. This study examined whether circulating adipocytokines, independent of adiposity, predicted pubertal changes in insulin sensitivity (SI), insulin secretion (AIR), and β-cell function in high-risk adolescents.

METHODS

158 Hispanic adolescents with overweight or obesity were followed for a median of 4 years. Adipocytokines were measured using Luminex technology. SI, AIR, and the disposition index were derived from an intravenous glucose tolerance test and minimal modeling. Total fat mass was measured by DXA and visceral adipose tissue (VAT) by MRI.

RESULTS

Surprisingly, mean IL-8, IL-1β, IL-6, and TNF-α decreased between 5% and 6.5% per year from baseline (P < 0.001). Despite the general temporal trends, gaining 1-SD of VAT was associated with a 2% and 5% increase in MCP-1 and IL-8 (P < 0.05). In addition, a 1-SD higher MCP-1 or IL-6 concentration at baseline was associated with a 16% and 21% greater decline in SI during puberty vs. prepuberty (P < 0.05).

CONCLUSIONS

Several adipocytokines decreased during adolescence and were weakly associated with VAT and lower SI during puberty. Circulating adipocytokines have relatively limited associations with pubertal changes in diabetes risk; however, the consistent findings with MCP-1 warrant further investigation.

Multimarker approach in discriminating patients with symptomatic and asymptomatic atherosclerotic carotid artery stenosis

Background and Purpose

Several circulating biomarkers have been implicated in carotid atherosclerotic plaque rupture and thrombosis; however, their clinical utility remains unknown. The aim of this study was to determine the role of a large biomarker panel in the discrimination of symptomatic (S) vs. asymptomatic (A/S) subjects in a contemporary population with carotid artery stenosis (CS).

Methods

Prospective sampling of circulating cytokines and blood lipids was performed in 300 unselected, consecutive patients with ≥50% CS, as assessed by duplex ultrasound (age 47-83 years; 110 with A/S and 190 with S) who were referred for potential CS revascularization.

Results

CS severity and pharmacotherapy did not differ between the A/S and S patients. The median values of total cholesterol, low-density lipoprotein cholesterol, and lipoprotein(a) did not differ, but high-density lipoprotein (HDL) cholesterol was significantly higher (p<0.001) and triglycerides were lower (p=0.03) in the A/S-CS group than in the S-CS group. Interleukin-6 (IL-6) and high-sensitivity C-reactive protein were higher (p=0.04 and p=0.07, respectively) in the S-CS group. Circulating visfatin, soluble CD 40 receptor ligand, soluble vascular cell adhesion molecule, leptin, adiponectin, IL-1β, IL-8, IL-18, monocyte chemoattractant protein-1, myeloperoxidase, matrix metalloproteinases-8, -9, and -10, and fibrinogen were similar, but tissue inhibitor of matrix metalloproteinases-1 (TIMP) was reduced in S-CS compared to A/S-CS (p=0.02). Nevertheless, incorporation of TIMP and IL-6 did not improve the HDL-cholesterol receiver operating characteristics for S-CS status prediction. S-CS status was unrelated to angiographic stenosis severity or plaque burden, as assessed by intravascular ultrasound (p=0.16 and p=0.67, respectively). Multivariate logistic regression analysis revealed low HDL-cholesterol to be the only independent predictor of CS symptoms, with an odds ratio of 1.81 (95% confidence interval=1.15-2.84, p=0.01) for HDL <1.00 mmol/L (first quartile) vs. >1.37 (third quartile). In S-CS, osteoprotegerin and lipoprotein-associated phospholipase A₂ (Lp-PLA₂) were elevated in those with recent vs. remote symptoms (p=0.01 and p=0.02, respectively).

Conclusions

In an all-comer CS population on contemporary pharmacotherapy, low HDL-cholesterol (but not other previously implicated or several novel circulating biomarkers) is an independent predictor of S-CS status. In addition, an increase in circulating osteoprotegerin and Lp-PLA₂ may transiently indicate S transformation of the carotid atherosclerotic plaque.

A high-fat diet is associated with endotoxemia that originates from the gut

Endotoxemia, characterized by an excess of circulating bacterial wall lipopolysaccharide, is associated with systemic inflammation and the metabolic syndrome. Placing 8 healthy subjects on a Western-style diet for 1 month induced a 71% increase in plasma levels of endotoxin activity (endotoxemia), whereas a prudent-style diet reduced levels by 31%. The Western-style diet might, therefore, contribute to endotoxemia by causing changes in gastrointestinal barrier function or the composition of the microbiota. Endotoxemia might also develop in individuals with gastrointestinal barrier impairment. Therapeutic reagents that reduce endotoxemia might reduce systemic inflammation in patients with gastrointestinal diseases or metabolic syndrome.