Serum zonulin as an index of glucose dysregulation in children and adolescents with overweight and obesity

Markers of Intestinal Permeability and Inflammation in Enterally Fed Children with Cerebral Palsy

Cerebral palsy (CP) results in non-progressive damage to the central nervous system, leading to functional disorders of the gastrointestinal tract and requiring enteral nutrition via gastrostomy in some patients. The aim of the study was to assess the impact of enteral nutrition on intestinal inflammation expressed by stool calprotectin and intestinal permeability determined by fecal zonulin and IFABP, and to determine whether CP affects these parameters. The study group consisted of 30 children with CP, fed enterally (Cerebral Palsy Enteral Nutrition-CPEN), and two reference groups: 24 children with CP, fed orally with a standard diet (CPC-Cerebral Palsy Controls) and 24 healthy children (HC-healthy controls). The differences between these groups and between the combined CP groups (CPG and CPEN + CPC) and HC were analyzed. Fecal zonulin, calprotectin, and intestinal fatty acid-binding protein 2 (IFABP2) levels were determined by ELISA. The concentrations of fecal calprotectin and zonulin were significantly higher in the CPEN group than in the CPC group (p = 0.012, p = 0.025). When comparing the CPG (n = 53) with the HC group (n = 24), statistically significant differences were observed for calprotectin (p = 0.000018, higher in the CPG) and IFABP (p = 0.021, higher in HC). Enteral nutrition was associated in our cohort with increased fecal calprotectin and zonulin. Children with cerebral palsy presented with increased fecal calprotectin but not increased intestinal permeability expressed by stool zonulin.

Gut permeability is associated with lower insulin sensitivity in youth with perinatally acquired HIV

The relationships between alterations in the intestinal barrier, and bacterial translocation with the development of metabolic complications in youth with perinatally acquired HIV (YPHIV) have not been investigated. The PHACS Adolescent Master Protocol enrolled YPHIV across 15 U.S. sites, including Puerto Rico, from 2007 to 2009. For this analysis, we included YPHIV with HIV viral load 1000 c/ml or less, with at least one measurement of homeostatic assessment of insulin resistance (HOMA-IR) or nonhigh density lipoprotein (non-HDLc) between baseline and year 3 and plasma levels of intestinal fatty-acid binding protein (I-FABP), lipopolysaccharide-binding protein (LBP), and zonulin levels at baseline. We fit linear regression models using generalized estimating equations to assess the association of baseline log 10 gut markers with log 10 HOMA-IR and non-HDLc at all timepoints. HOMA-IR or non-HDLc was measured in 237, 189, and 170 PHIV at baseline, Yr2, and Yr3, respectively. At baseline, median age (Q1, Q3) was 12 years (10, 14), CD4 + cell count was 762 cells/μl (574, 984); 90% had HIV RNA less than 400 c/ml. For every 10-fold higher baseline I-FABP, HOMA-IR dropped 0.85-fold at baseline and Yr2. For a 10-fold higher baseline zonulin, there was a 1.35-fold increase in HOMA-IR at baseline, 1.23-fold increase in HOMA-IR at Yr2, and 1.20-fold increase in HOMA-IR at Yr3 in adjusted models. For a 10-fold higher baseline LBP, there was a 1.23-fold increase in HOMA-IR at baseline in the unadjusted model, but this was slightly attenuated in the adjusted model. Zonulin was associated with non-HDLc at baseline, but not for the other time points. Despite viral suppression, intestinal damage may influence downstream insulin sensitivity in YPHIV.

Fasting and meal-related zonulin serum levels in a large cohort of obese children and adolescents

Introduction

Zonulin recently emerged as a valuable biological marker to assess the integrity of the intestinal mucosal barrier. Nevertheless, data about zonulin in pediatric age are extremely scarce. Aim of this study was to investigate the relationship between serum zonulin levels, both fasting and postprandial, with body mass index (BMI) and biochemical markers of insulin resistance (IR), insulin sensitivity, b-cell function and cardio-metabolic risk in obese non-diabetic youths.

Methods

One hundred and four children and adolescents with obesity (BMI ≥ 2.0 SDS) were enrolled (mean age 11.43 ± 2.66). All the patients underwent clinical and biochemical assessment, including oral glucose tolerance test (OGTT) and liver ultrasonography. Zonulin serum levels were measured at fasting state, at 60-minute and 120-minute OGTT timepoint.

Results

Impaired fasting glycaemia and impaired glucose tolerance were documented in 27.9% and 11.5% of patients, respectively. IR was documented in 69.2% of cases. Liver steatosis was diagnosed in 39.4%. Zonulin serum levels significantly increased from baseline to 60-minute and 120-minute OGTT timepoint (p positive correlation between BMI SDS and serum zonulin levels at 120-minute OGTT timepoint (p highlighted a positive association of zonulin fasting levels with IR and glutamicoxalacetic transaminase levels (GOT, p zonulin levels were demonstrated for age, sex, pubertal status, glucose, lipid profile and the other obesity-related parameters.

Discussion

Our results show, for the first time in a pediatric cohort, the meal-related pattern of secretion of serum zonulin, which tends to significantly increase during and at 2-hours postprandial assessment. Even if the underlying mechanisms associating intestinal permeability and obesity have not been fully elucidated yet, our data confirm a close relationship between zonulin concentration and obesity in pediatric population. IR seems to significantly influence zonulin serum levels, thus a central role of IR in this pathway is conceivable.

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.

Zonulin as a Potential Therapeutic Target in Microbiota-Gut-Brain Axis Disorders: Encouraging Results and Emerging Questions

The relationship between dysbiosis and central nervous diseases has been proved in the last 10 years. Microbial alterations cause increased intestinal permeability, and the penetration of bacterial fragment and toxins induces local and systemic inflammatory processes, affecting distant organs, including the brain. Therefore, the integrity of the intestinal epithelial barrier plays a central role in the microbiota-gut-brain axis. In this review, we discuss recent findings on zonulin, an important tight junction regulator of intestinal epithelial cells, which is assumed to play a key role in maintaining of the blood-brain barrier function. In addition to focusing on the effect of microbiome on intestinal zonulin release, we also summarize potential pharmaceutical approaches to modulate zonulin-associated pathways with larazotide acetate and other zonulin receptor agonists or antagonists. The present review also addresses the emerging issues, including the use of misleading nomenclature or the unsolved questions about the exact protein sequence of zonulin.