Low-grade endotoxemia, gut permeability and platelet activation in patients with impaired fasting glucose

Risk of venous thromboembolism in autoimmune diseases: A comprehensive review

Autoimmune diseases have specific pathophysiologic mechanisms leading to an increased risk of arterial and venous thrombosis. The risk of venous thromboembolism (VTE) varies according to the type and stage of the disease, and to concomitant treatments. In this review, we revise the most common autoimmune disease such as antiphospholipid syndrome, inflammatory myositis, polymyositis and dermatomyositis, rheumatoid arthritis, sarcoidosis, Sjogren syndrome, autoimmune haemolytic anaemia, systemic lupus erythematosus, systemic sclerosis, vasculitis and inflammatory bowel disease. We also provide an overview of pathophysiology responsible for the risk of VTE in each autoimmune disorder, and report current indications to anticoagulant treatment for primary and secondary prevention of VTE.

Inflammatory and intestinal permeability biomarkers in healthy participants on long term vegan, vegetarian, omnivore and low-carbohydrate high-fat diet

Vegan, vegetarian and low-carbohydrate high fat (LCHF) diets can all offer several health benefits, if food choices are appropriate. In most studies examining their effects on systemic inflammation, participants were either overweight, on a weight loss programme or not matched for BMI, or had a pre-existing condition such as type 2 diabetes mellitus or hypertension. Little is known about the effects of dietary patterns on healthy and normal weight individuals. The aim of the present study was therefore to assess and directly compare inflammatory and intestinal permeability status in healthy participants following aforementioned or omnivore diet for at least 6 months. In this cross-sectional study, we measured the inflammatory biomarkers IL-6, TNF-α and CRP, and the markers of intestinal permeability LBP and zonulin, along with the analysis of lifestyle aspects, dietary intakes and physical activity, in 89 healthy participants. The groups were matched for sex, age and BMI. There were no differences in any of the measured parameters between the four groups and we found no strong correlations with dietary intakes. Using cluster analysis, participants were divided into eight clusters with more or less favourable inflammatory profiles; all clusters contained representatives of all patterns and all patterns were represented in each cluster. Significant differences between clusters were in the intake of mono-unsaturated fatty acids, ω-3/ω-6 ratio, phase angle and working two shifts. In healthy, normal-weight individuals, inflammatory status therefore does not depend on the dietary pattern itself, but is rather more complexly regulated and associated with dietary and non-dietary factors.

Gut-derived low-grade endotoxaemia, atherothrombosis and cardiovascular disease

Systemic inflammation has been suggested to have a pivotal role in atherothrombosis, but the factors that trigger systemic inflammation have not been fully elucidated. Lipopolysaccharide (LPS) is a component of the membrane of Gram-negative bacteria present in the gut that can translocate into the systemic circulation, causing non-septic, low-grade endotoxaemia. Gut dysbiosis is a major determinant of low-grade endotoxaemia via dysfunction of the intestinal barrier scaffold, which is a prerequisite for LPS translocation into the systemic circulation. Experimental studies have demonstrated that LPS is present in atherosclerotic arteries but not in normal arteries. In atherosclerotic plaques, LPS promotes a pro-inflammatory status that can lead to plaque instability and thrombus formation. Low-grade endotoxaemia affects several cell types, including leukocytes, platelets and endothelial cells, leading to inflammation and clot formation. Low-grade endotoxaemia has been described in patients at risk of or with overt cardiovascular disease, in whom low-grade endotoxaemia was associated with atherosclerotic burden and its clinical sequelae. In this Review, we describe the mechanisms favouring the development of low-grade endotoxaemia, focusing on gut dysbiosis and changes in gut permeability; the plausible biological mechanisms linking low-grade endotoxaemia and atherothrombosis; the clinical studies suggesting that low-grade endotoxaemia is a risk factor for cardiovascular events; and the potential therapeutic tools to improve gut permeability and eventually eliminate low-grade endotoxaemia.

Extra Virgin Olive Oil Reduces Gut Permeability and Metabolic Endotoxemia in Diabetic Patients

Background: Extra virgin olive oil (EVOO) improves post-prandial glycemia, but the underlying mechanism has not been fully elucidated. We tested the hypothesis that EVOO improves post-prandial glycemia by reducing gut permeability-derived low-grade endotoxemia. Methods: Serum levels of lipopolysaccharides (LPS), zonulin, a marker of gut permeability, glucose, insulin and glucagon-like peptide 1 (GLP1) were measured in 20 patients with impaired fasting glucose (IFG) and 20 healthy subjects (HS) matched for sex and age. The same variables were measured in IFG patients (n = 20) and HS (n = 20) before and after a Mediterranean diet with 10 g EVOO added or not (n = 20) or in IFG patients (n = 20) before and after intake of 40 g chocolate with EVOO added or not. Results: Compared to HS, IFG had higher levels of LPS and zonulin. In HS, meal intake was associated with a significant increase of blood glucose, insulin, and GLP1 with no changes of blood LPS and zonulin. Two hours after a meal intake containing EVOO, IFG patients showed a less significant increase of blood glucose, a more marked increase of blood insulin and GLP1 and a significant reduction of LPS and zonulin compared to IFG patients not given EVOO. Correlation analysis showed that LPS directly correlated with blood glucose and zonulin and inversely with blood insulin. Similar findings were detected in IFG patients given a chocolate added or without EVOO. Conclusion: Addition of EVOO to a Mediterranean diet or chocolate improves gut permeability and low-grade endotoxemia.

Effects of liraglutide vs. lifestyle changes on soluble suppression of tumorigenesis-2 (sST2) and galectin-3 in obese subjects with prediabetes or type 2 diabetes after comparable weight loss

Background

Soluble suppression of tumorigenesis-2 (sST2) and galectin (Gal)-3 are two biomarkers related to inflammation, metabolic disturbances and to myocardial fibrosis that characterize several cardiac pathological conditions. Increased circulating levels of these molecules have been associated with risk of cardiovascular death. Treatment with liraglutide, a glucagon-like peptide 1 analog, is associated with weight loss, improved glycemic control, and reduced cardiovascular risk. We wanted to assess (I) potential differences between subjects with prediabetes or type 2 diabetes mellitus (T2DM) and healthy controls in sST2 and Gal-3 circulating levels, and their relationship with glycemic control and markers of beta cell function and myocardial injury; (II) whether liraglutide treatment modulates these markers in subjects with prediabetes or early T2DM independently of weight loss; (III) whether baseline levels of any of these two molecules may predict the response to liraglutide treatment.

Methods

Forty metformin-treated obese subjects (BMI ≥ 30) with prediabetes [impaired fasting glucose (IFG) or impaired glucose tolerance (IGT) or both (n = 23)] or newly diagnosed T2DM (n = 17), were randomized to liraglutide or lifestyle counseling until achieving a comparable weight loss (7% of initial body weight). Thirteen subjects were enrolled as healthy controls for baseline sST2 and Gal-3 levels.

Results

Baseline sST2 levels were comparable between controls and obese patients (p = 0.79) whereas Gal-3 levels were significantly higher in patients as compared to controls (p < 0.001). Liraglutide treatment, but not weight loss achieved by lifestyle counseling, decreased plasma sST2 levels (− 9%, beta = − 14.9, standard deviation 6.9, p = 0.037) while Gal-3 levels did not change. A reduction in serum hs-Troponin I was observed after intervention, due to a 19% (p = 0.29) increase in the lifestyle arm, and a 25% decrease (p = 0.033) in the liraglutide arm (between-group difference p = 0.083). Lower baseline Gal-3 levels predicted a better improvement in beta cell function after liraglutide treatment.

Conclusions

Liraglutide-induced reduction in sST2 and possibly hs-TnI suggests that in obese patients with prediabetes or early T2DM this drug may have a positive effect on (cardiac) fibrosis, whereas plasma level of Gal-3 before liraglutide initiation may predict response to the drug in terms of beta cell function improvement.

Trial registration Eudract: 2013-001356-36

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01469-w.

The role of Intestinal-Fatty Acid Binding Proteins and Chitinase-3-Like Protein 1 across the spectrum of dysglycemia

BACKGROUND AND AIMS

Recent studies underlie the importance of intestinal permeability and chronic inflammation in the pathogenesis of T2DM. Our study compared the concentrations of FABP2 and YKL40 as markers of intestinal permeability and inflammation among normoglycemia, prediabetes and T2DM.

METHODS

We recruited 122 participants (45 normoglycemic, 26 prediabetes, and 51 T2DM) of whom we measured the fasting serum levels of FABP2 and YKL-40 using ELISA method.

RESULTS

The levels of FABP2 were significantly higher in the T2DM group [2.890 (1.880-4.070)] in comparison to both prediabetes [2.025 (1.145-2.343), p = 0.0085] and normoglycemia group [1.72 (1.250-2.645), p = 0.011]. The levels of YKL-40 were also significantly higher in the T2DM group [68.70 (44.61-166.6)] in comparison to both prediabetes [28.85 (20.64-41.53), p < 0.0001] and normoglycemia group [28.64 (19.25-43.87), p < 0.001].

CONCLUSIONS

Our study observed that the levels of FABP2 and YKL-40 were highest in the T2DM group supporting the available evidences on the role of intestinal permeability disruption and chronic low-grade inflammation in the pathogenesis of T2DM.

Possible Benefits of Faecalibacterium prausnitzii for Obesity-Associated Gut Disorders

Metabolic disorders are an increasing concern in the industrialized world. Current research has shown a direct link between the composition of the gut microbiota and the pathogenesis of obesity and diabetes. In only a few weeks, an obesity-inducing diet can lead to increased gut permeability and microbial dysbiosis, which contributes to chronic inflammation in the gut and adipose tissues, and to the development of insulin resistance. In this review, we examine the interplay between gut inflammation, insulin resistance, and the gut microbiota, and discuss how some probiotic species can be used to modulate gut homeostasis. We focus primarily on Faecalibacterium prausnitzii, a highly abundant butyrate-producing bacterium that has been proposed both as a biomarker for the development of different gut pathologies and as a potential treatment due to its production of anti-inflammatory metabolites.

Microbiome in Blood Samples From the General Population Recruited in the MARK-AGE Project: A Pilot Study

The presence of circulating microbiome in blood has been reported in both physiological and pathological conditions, although its origins, identities and function remain to be elucidated. This study aimed to investigate the presence of blood microbiome by quantitative real-time PCRs targeting the 16S rRNA gene. To our knowledge, this is the first study in which the circulating microbiome has been analyzed in such a large sample of individuals since the study was carried out on 1285 Randomly recruited Age-Stratified Individuals from the General population (RASIG). The samples came from several different European countries recruited within the EU Project MARK-AGE in which a series of clinical biochemical parameters were determined. The results obtained reveal an association between microbial DNA copy number and geographic origin. By contrast, no gender and age-related difference emerged, thus demonstrating the role of the environment in influencing the above levels independent of age and gender at least until the age of 75. In addition, a significant positive association was found with Free Fatty Acids (FFA) levels, leukocyte count, insulin, and glucose levels. Since these factors play an essential role in both health and disease conditions, their association with the extent of the blood microbiome leads us to consider the blood microbiome as a potential biomarker of human health.

Could serum zonulin be an intestinal permeability marker in diabetes kidney disease?

Zonulin is a protein associated with the tight junction complex opening at the intestinal epithelium, previously linked to obesity, cardiovascular diseases, type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD). However, its role in CKD has not been totally elucidated. This study aimed to evaluate zonulin levels in subjects with diabetic kidney disease (DKD). This case-control study included two cases groups: 1) Advanced DKD cases: T2DM patients with estimated glomerular filtration rate (eGFR) <60ml/min/1.73m²; 2) Albuminuric T2DM cases: diabetic patients with urinary albumin excretion (UAE) >30mg/g creatinine, but with eGFR>60ml/min/1.73m². Two control groups were also included: 1) T2DM controls: patients with T2DM without impaired kidney function; 2) Non-T2DM controls: subjects without T2DM and normal renal function. Serum levels of zonulin were measured by ELISA. Eighty-six individuals were included. Zonulin levels was different among study groups (P = 0.003). T2DM controls presented higher zonulin levels than non-T2DM controls [(131.35 (83.0–170.5) vs. 87.25 (54.7–111.8), P = 0.018] and advanced DKD cases [63.72 (45.03–106.0); P = 0.007]. Zonulin showed a positive correlation with eGFR (r = 0.222; P = 0.040), total cholesterol (r = 0.299; P = 0.034), LDL (r = 0.258; P = 0.021), and negative with albuminuria (r = -0.243; P = 0.024) and body fat (r = -0.271; P = 0.014). In the multivariate logistic regression analyses, zonulin levels were independently associated to renal outcomes [OR 0.99 (0.98–0.99, P = 0.012)] after 5-year inclusion. In conclusion, increased zonulin levels in patients with TD2M without renal disease suggest an impaired intestinal permeability. Moreover, its association with renal outcomes could indicate its use as a disease monitoring marker. However, the mechanisms behind this association should be better understood.

Nonalcoholic fatty liver disease (NAFLD) severity is associated to a nonhemostatic contribution and proinflammatory phenotype of platelets

Nonalcoholic fatty liver disease (NAFLD) is the main cause of chronic liver disease and ranges from simple steatosis to nonalcoholic steatohepatitis. Recently, a platelet role in NAFLD pathogenesis and progression has been reported in mouse models and in patients. We investigated whether platelets are involved in liver and systemic inflammation processes in NAFLD. In this exploratory study we recruited 24 consecutive patients with biopsy-proven diagnosis of NAFLD and 17 healthy volunteers. We measured plasma levels of inflammatory markers by ELISA. We investigated hemostatic and inflammatory transcripts in circulating platelets and leukocytes from NAFLD patients. We analyzed platelet and neutrophil extracellular traps (NET) accumulations in liver sinusoids using CD42 and H3 citrullinated histones immunohistochemical staining on liver biopsies. NAFLD patients had increased inflammation markers and lipolysaccharides plasma levels. We found significant increase of inflammatory transcripts in circulating platelets and not in leukocytes of NAFLD subjects compared with healthy controls. We demonstrated increased intrahepatic platelet accumulation that correlated with NAFLD activity score (NAS) score and intrahepatic neutrophil extracellular traps (NET) formation in liver biopsies of NAFLD patients. NET formation was higher in livers with higher NAS and inflammation scores. The presence of low-grade systemic inflammation and proinflammatory changes of circulating platelets indicate that platelets participate on systemic inflammatory changes associated with NAFLD. Liver platelet accumulation and liver NET formation, together with low-grade endotoxemia, suggest that platelets may act to protect the liver from invading microorganisms by favoring local NET formation.

Increased serum ferritin is associated with oxidized low-density lipoprotein in prediabetes patients: A pilot study

Aims

This pilot study aimed to determine if increased serum ferritin (SF) is associated with cardiovascular risk factors in patients with prediabetes.

Methods

Eighteen patients with prediabetes and 36 subjects without prediabetes (control), non-white Hispanic, non-indigenous origin, Mexican mestizo descent were included. Participants had no inflammation, or vascular complications. SF and metabolic markers were evaluated in both groups.

Results

SF and oxidized low-density lipoprotein (oxLDL) were increased in prediabetes subjects. Moreover, in prediabetes and control groups as a whole, natural logarithm (ln)-SF correlated with oxLDL and ln-oxLDL/LDL after adjustment for sex, ln-age, ln-fasting plasma glucose (FPG), ln-body mass index, ln-triglyceride (TG), total cholesterol (TC), and high-density lipoproteins. Finally, ln-SF was an independent contributor to ln-oxLDL/LDL ratio in control and prediabetes subjects (β = 0.2915) after the introduction of potential confounders such as FPG, TC, TG, and hypertension.

Conclusions

The results of this study indicate that hyperferritinemia is associated with oxLDL, considered one of the main cardiovascular risk factors, which allows us to suggest that an increase in SF could contribute to the progression of prediabetes, prior to the appearance of diabetes. Further research is required to establish a causal relationship of iron disruption metabolism in oxLDL generation under prediabetes conditions.

The Role of Antioxidants Supplementation in Clinical Practice: Focus on Cardiovascular Risk Factors

Oxidative stress may be defined as an imbalance between reactive oxygen species (ROS) and the antioxidant system to counteract or detoxify these potentially damaging molecules. This phenomenon is a common feature of many human disorders, such as cardiovascular disease. Many of the risk factors, including smoking, hypertension, hypercholesterolemia, diabetes, and obesity, are associated with an increased risk of developing cardiovascular disease, involving an elevated oxidative stress burden (either due to enhanced ROS production or decreased antioxidant protection). There are many therapeutic options to treat oxidative stress-associated cardiovascular diseases. Numerous studies have focused on the utility of antioxidant supplementation. However, whether antioxidant supplementation has any preventive and/or therapeutic value in cardiovascular pathology is still a matter of debate. In this review, we provide a detailed description of oxidative stress biomarkers in several cardiovascular risk factors. We also discuss the clinical implications of the supplementation with several classes of antioxidants, and their potential role for protecting against cardiovascular risk factors.

The Inflammasome in Chronic Complications of Diabetes and Related Metabolic Disorders

Diabetes mellitus (DM) ranks seventh as a cause of death worldwide. Chronic complications, including cardiovascular, renal, and eye disease, as well as DM-associated non-alcoholic fatty liver disease (NAFLD) account for most of the morbidity and premature mortality in DM. Despite continuous improvements in the management of late complications of DM, significant gaps remain. Therefore, searching for additional strategies to prevent these serious DM-related conditions is of the utmost importance. DM is characterized by a state of low-grade chronic inflammation, which is critical in the progression of complications. Recent clinical trials indicate that targeting the prototypic pro-inflammatory cytokine interleukin-1β (IL-1 β) improves the outcomes of cardiovascular disease, which is the first cause of death in DM patients. Together with IL-18, IL-1β is processed and secreted by the inflammasomes, a class of multiprotein complexes that coordinate inflammatory responses. Several DM-related metabolic factors, including reactive oxygen species, glyco/lipoxidation end products, and cholesterol crystals, have been involved in the pathogenesis of diabetic kidney disease, and diabetic retinopathy, and in the promoting effect of DM on the onset and progression of atherosclerosis and NAFLD. These metabolic factors are also well-established danger signals capable of regulating inflammasome activity. In addition to presenting the current state of knowledge, this review discusses how the mechanistic understanding of inflammasome regulation by metabolic danger signals may hopefully lead to novel therapeutic strategies targeting inflammation for a more effective treatment of diabetic complications.

Poor Adherence to Mediterranean Diet and Serum Lipopolysaccharide are Associated with Oxidative Stress in Patients with Non-Alcoholic Fatty Liver Disease

Oxidative stress plays a pivotal role in non-alcoholic fatty liver disease (NAFLD). Factors inducing oxidative stress in NAFLD may be several; however, a relationship with the adherence to Mediterranean Diet (Med-diet) and with serum lipopolysaccharide (LPS) has been poorly investigated in this setting. The aim was to investigate factors associated with impaired oxidative stress in NAFLD, focusing on the potential role of LPS and Med-diet. We enrolled 238 consecutive outpatients from the PLINIO study, in whom we measured the soluble Nox2-derived peptide (sNox2-dp), a marker of systemic oxidative stress, and serum LPS. Adherence to Med-diet was investigated by a nine-item validated dietary questionnaire. Serum sNox2-dp and LPS were higher in patients with NAFLD compared to those without (25.0 vs. 9.0 pg/mL, p < 0.001 and 62.0 vs. 44.9 pg/mL, p < 0.001, respectively). In patients with NAFLD, the highest sNox2-dp tertile was associated with the top serum LPS tertile (Odds Ratio (OR): 4.71; p < 0.001), APRI > 0.7 (OR: 6.96; p = 0.005) and Med-diet-score > 6 (OR: 0.14; p = 0.026). Analyzing individual foods, the daily consumption of wine (OR: 0.29, p = 0.046) and the adequate weekly consumption of fish (OR: 0.32, p = 0.030) inversely correlated with the top sNox2-dp tertile. In conclusion, patients with NAFLD showed impaired oxidative stress. Levels of sNox2 correlated with serum LPS and with low adherence to Med-Diet.

Intestinal-level anti-inflammatory bioactivities of catechin-rich green tea: Rationale, design, and methods of a double-blind, randomized, placebo-controlled crossover trial in metabolic syndrome and healthy adults

Metabolic endotoxemia initiates low-grade chronic inflammation in metabolic syndrome (MetS) and provokes the progression towards more advanced cardiometabolic disorders. Our recent works in obese rodent models demonstrate that catechin-rich green tea extract (GTE) improves gut barrier integrity to alleviate the translocation of gut-derived endotoxin and its consequent pro-inflammatory responses mediated through Toll-like receptor-4/nuclear factor κB (TLR4/NFκB) signaling. The objective of this clinical trial is to establish the efficacy of GTE to alleviate metabolic endotoxemia-associated inflammation in persons with MetS by improving gut barrier function. We plan a double-blind, placebo-controlled cross-over trial in persons with MetS and age- and gender-matched healthy persons (18–65 y; n = 20/group) who will receive a low-energy GTE-rich (1 g/day; 890 mg total catechins) confection snack food while following a low-polyphenol diet for 28 days. Assessments will include measures of circulating endotoxin (primary outcome) and secondary outcomes including biomarkers of endotoxin exposure, region-specific measures of intestinal permeability, gut microbiota composition, diversity, and functions, intestinal and systemic inflammatory responses, and catechins and microbiota-derived catechin metabolites. Study outcomes will provide the first report of the GTE-mediated benefits that alleviate gut barrier dysfunction in relation to endotoxemia-associated inflammation in MetS persons. This is expected to help establish an effective dietary strategy to mitigate the growing burden of MetS that currently affects ~35% of Americans.

Risk factors associated with intestinal permeability in an adult population: A systematic review

BACKGROUND

Increased intestinal permeability (IP) involves the loss of integrity between the cells of the small intestine. IP has been suggested to contribute to the pathogenesis and exacerbation of many chronic diseases. Many potential risk factors for IP are proposed in contemporary literature. The purpose of this review is to identify the most significant risk factors for IP.

METHODS

A systematic search of literature published up until September 2018 in the PubMed, EMBASE, CINAHL, and Scopus databases was conducted.

RESULTS

A total of 47 articles met the inclusion criteria. Elevated levels of proinflammatory markers, dyslipidaemia, hyperglycaemia, insulin resistance, anthropometric measurements resembling obesity, advanced disease severity, comorbidity and the consumption of a Western-style diet were identified as the strongest risk factors for altered intestinal integrity. The risk of IP increases when coupled with a multiple disease state or combined with other environmental risk factors. Furthermore, many of the identified risk factors such as anthropometric measurements and biomarkers were external from intestinal health and rather resembled a metabolic-like condition.

CONCLUSIONS

This review identified a number of potential risk factors for IP, ranging from biomarkers to anthropometric measurements, demographics, dietary intake and chronic diseases. These risk factors warrant the attention of clinicians and other healthcare providers to aid the identification of potential patients at risk of altered IP. Further research needs to examine whether the identified risk factors are homogeneous with the diagnosis of IP or whether the disease state influences the association.

NAFLD and Diabetes: Two Sides of the Same Coin? Rationale for Gene-Based Personalized NAFLD Treatment

The prevalence of non-alcoholic fatty liver disease (NAFLD) has been increasing rapidly and at the forefront of worldwide concern. Characterized by excessive fat accumulation in the liver, NAFLD regularly coexists with metabolic disorders, including type 2 diabetes, obesity, and cardiovascular disease. It has been well established that the presence of NAFLD increases the incidence of type 2 diabetes, while diabetes aggravates NAFLD to more severe forms of steatohepatitis, cirrhosis, and hepatocellular carcinoma. However, recent progress on the genotype/phenotype relationships in NAFLD patients indicates the development of NAFLD with a relative conservation of glucose metabolism in individuals with specific gene variants, such as the patatin-like phospholipase domain-containing 3 (PNPLA3) and transmembrane 6 superfamily member 2 protein (TM6SF2) variants. This review will focus on the clinical and pathophysiological connections between NAFLD and type 2 diabetes and will also discuss a disproportionate progression of NAFLD and diabetes, and the different responses to lifestyle and drug intervention in NAFLD patients with specific gene variants that may give insight into personalized treatment for NAFLD.

Role for diet in normal gut barrier function: developing guidance within the framework of food-labeling regulations

A reduction in intestinal barrier function is currently believed to play an important role in pathogenesis of many diseases, as it facilitates passage of injurious factors such as lipopolysaccharide, peptidoglycan, whole bacteria, and other toxins to traverse the barrier to damage the intestine or enter the portal circulation. Currently available evidence in animal models and in vitro systems has shown that certain dietary interventions can be used to reinforce the intestinal barrier to prevent the development of disease. The relevance of these studies to human health is unknown. Herein, we define the components of the intestinal barrier, review available modalities to assess its structure and function in humans, and review the available evidence in model systems or perturbations in humans that diet can be used to fortify intestinal barrier function. Acknowledging the technical challenges and the present gaps in knowledge, we provide a conceptual framework by which evidence could be developed to support the notion that diet can reinforce human intestinal barrier function to restore normal function and potentially reduce the risk for disease. Such evidence would provide information on the development of healthier diets and serve to provide a framework by which federal agencies such as the US Food and Drug Administration can evaluate evidence linking diet with normal human structure/function claims focused on reducing risk of disease in the general public.

Platelet number in different anticoagulants as a diagnostic biomarker for increased intestinal permeability

The main pathological process associated to increased intestinal permeability is the translocation of toxic products, predominantly endotoxins/lipopolysaccharide (LPS), from the intestinal tract into the microcirculation. In blood, LPS binds to surface receptors on immune cells initiating an inflammatory response. LPS can also bind to platelets leading to preactivated platelets that have a lower threshold to be aggregated in presence heparin. The aim of this study was to validate a simple, fast and reliable test for screening LPS-loaded platelets. This test named PANDA (acronym for Platelet Number in Different Anticoagulants) consists in the measurement of the mean platelet number in blood samples collected into EDTA and heparin. We analyzed blood samples from 92 patients with gastrointestinal diseases and 23 healthy volunteers and found a markedly low number of platelets in heparinized blood compared to EDTA-anticoagulated blood in patients but not in healthy volunteers. Furthermore, ex vivo addition of endotoxin to blood samples induced a remarkable decrease in platelet count in heparinized blood of the volunteers but not in the patient's group, where platelets could be previously saturated by endotoxin circulating in blood. Platelet should be counted during the first hour after blood collection, in order to avoid false results due to a progressive platelet aggregation in heparinized blood in function of the time. Our results demonstrated that PANDA test can be used for screening LPS-loaded platelets as an indirect diagnostic biomarker for increased intestinal permeability and also for monitoring the gut barrier function during the treatment of gastrointestinal diseases.

Gut microbiota, dietary intakes and intestinal permeability reflected by serum zonulin in women

PURPOSE

Increased gut permeability causes the trespass of antigens into the blood stream which leads to inflammation. Gut permeability reflected by serum zonulin and diversity of the gut microbiome were investigated in this cross-sectional study involving female study participants with different activity and BMI levels.

METHODS

102 women were included (BMI range 13.24-46.89 kg m^-2): Anorexia nervosa patients (n = 17), athletes (n = 20), normal weight (n = 25), overweight (n = 21) and obese women (n = 19). DNA was extracted from stool samples and subjected to 16S rRNA gene analysis (V1-V2). Quantitative Insights Into Microbial Ecology (QIIME) was used to analyze data. Zonulin was measured with ELISA. Nutrient intake was assessed by repeated 24-h dietary recalls. We used the median of serum zonulin concentration to divide our participants into a "high-zonulin" (> 53.64 ng/ml) and "low-zonulin" (< 53.64 ng/ml) group.

RESULTS

The alpha-diversity (Shannon Index, Simpson Index, equitability) and beta-diversity (unweighted and weighted UniFrac distances) of the gut microbiome were not significantly different between the groups. Zonulin concentrations correlated significantly with total calorie-, protein-, carbohydrate-, sodium- and vitamin B12 intake. Linear discriminant analysis effect size (LEfSe) identified Ruminococcaceae (LDA = 4.163, p = 0.003) and Faecalibacterium (LDA = 4.151, p = 0.0002) as significantly more abundant in the low zonulin group.

CONCLUSION

Butyrate-producing gut bacteria such as Faecalibacteria could decrease gut permeability and lower inflammation. The diversity of the gut microbiota in women does not seem to be correlated with the serum zonulin concentration. Further interventional studies are needed to investigate gut mucosal permeability and the gut microbiome in the context of dietary factors.

Gut-derived lipopolysaccharides increase post-prandial oxidative stress via Nox2 activation in patients with impaired fasting glucose tolerance: effect of extra-virgin olive oil

PURPOSE

Post-prandial phase is characterized by enhanced oxidative stress but the underlying mechanism is unclear. We investigated if gut-derived lipopolysaccharide (LPS) is implicated in this phenomenon and the effect of extra virgin olive oil (EVOO) in patients with impaired fasting glucose (IFG).

METHODS

This is a randomized cross-over interventional study including 30 IFG patients, to receive a lunch with or without 10 g of EVOO. Serum LPS, Apo-B48, markers of oxidative stress such as oxidized LDL (oxLDL) and soluble Nox2-derived peptide (sNox2-dp), a marker of nicotinamide-adenine-dinucleotide-phosphate oxidase isoform Nox2 activation, and plasma polyphenols were determined before, 60 and 120 min after lunch.

RESULTS

In patients not given EVOO oxidative stress as assessed by sNox2-dp and oxLDL significantly increased at 60 and 120 min concomitantly with an increase of LPS and Apo-B48. In these patients, changes of LPS were correlated with Apo-B48 (Rs = 0.542, p = 0.002) and oxLDL (Rs = 0.463, p = 0.010). At 120 min, LPS (β - 15.73, p < 0.001), Apo-B48 (β - 0.14, p = 0.004), sNox2-dp (β - 5.47, p = 0.030), and oxLDL (β - 42.80, p < 0.001) significantly differed between the two treatment groups. An inverse correlation was detected between polyphenols and oxLDL (R - 0.474, p < 0.005). In vitro study showed that LPS, at the same concentrations found in the human circulation, up-regulated Nox2-derived oxidative stress via interaction with Toll-like receptor 4.

CONCLUSIONS

Post-prandial phase is characterized by an oxidative stress-related inflammation potentially triggered by LPS, a phenomenon mitigated by EVOO administration.