The role of adipose tissue and subsequent liver tissue hypoxia in obesity and early stage metabolic dysfunction associated steatotic liver disease

BACKGROUND

Obesity is linked to several health complication, including Metabolic Dysfunction Associated Steatotic Liver Disease (MASLD). Adipose tissue hypoxia has been suggested as an important player in the pathophysiological mechanism leading to chronic inflammation in obesity, and in the progression of MASLD. The study aims to investigate the effect of progressive obesity on adipose and liver tissue hypoxia.

METHODS

Male 8-week-old C57BL/6J mice were fed a high-fat high-fructose diet (HFHFD) or control diet (CD) for 4, 8, 12, 16 and 20 weeks. Serum ALT, AST and lipid levels were determined, and glucose and insulin tolerance testing was performed. Liver, gonadal and subcutaneous adipose tissue was assessed histologically. In vivo tissue pO2 measurements were performed in gonadal adipose tissue and liver under anesthesia. A PCR array for hypoxia responsive genes was performed in liver and adipose tissue. The main findings in the liver were validated in another diet-induced MASLD mice model, the choline-deficient L-amino acid defined high-fat diet (CDAHFD).

RESULTS

HFHFD feeding induced a progressive obesity, dyslipidaemia, insulin resistance and MASLD. In vivo pO2 was decreased in gonadal adipose tissue after 8 weeks of HFHFD compared to CD, and decreased further until 20 weeks. Liver pO2 was only significantly decreased after 16 and 20 weeks of HFHFD. Gene expression and histology confirmed the presence of hypoxia in liver and adipose tissue. Hypoxia could not be confirmed in mice fed a CDAHFD.

CONCLUSION

Diet-induced obesity in mice is associated with hypoxia in liver and adipose tissue. Adipose tissue hypoxia develops early in obesity, while liver hypoxia occurs later in the obesity development but still within the early stages of MASLD. Liver hypoxia could not be directly confirmed in a non-obese liver-only MASLD mice model, indicating that obesity-related processes such as adipose tissue hypoxia are important in the pathophysiology of obesity and MASLD.

How can peer teaching influence the development of medical students? a descriptive, longitudinal interview study

BACKGROUND

Peer-assisted learning (PAL) - where students take up a teaching role at an early stage of their training-is widely used in medical curricula. Many qualitative studies have investigated the perceptions and benefits of PAL, but no studies have longitudinally explored how peer teachers experienced their development. This could allow for a better understanding of PAL. In this study, we explored the perceived impact of being a peer teacher on the development of personal and professional competencies as a medical student.

METHODS

We longitudinally conducted semi-structured interviews with peer teachers, during their 2-year teaching period in the skills lab at the University of Antwerp and applied descriptive thematic analysis.

RESULTS

In total we gathered 47 interviews in 13 peer teachers (9 female, 4 male,. 1-7 interviews each). Peer teachers reported an increase in self-confidence, which gradually transformed into self-efficacy in clinical and teaching skills., Participants told us to be inspired by the previous generation of peer teachers. Their motivation shifted from personal benefits to benefiting others while becoming a role model themselves. The peer teachers illustrated how they developed maturity by integrating different CanMEDS roles. They grew in reflection, changed/transformed an initial mark-driven study drive into more patient-centered ambitions, and started developing a personal style.

CONCLUSIONS

Our study suggests that being a peer teacher leads to more self-efficacy, in clinical and teaching skills, to become a role model with as motivation to benefit others and to grow towards a good doctor maturity. Although the task is to teach peers, this opportunity nurtures the practice and integration of various CanMEDS roles, not only that of scholar but also communicator, collaborator and leader, thereby positively influencing their personal and professional development and their identity as a doctor (professional role).

Measuring Myeloperoxidase Activity as a Marker of Inflammation in Gut Tissue Samples of Mice and Rat

Myeloperoxidase (MPO) is an enzyme contained in lysosomal azurophilic granules of neutrophils. MPO activity has been shown to correlate with the number of neutrophils in histological sections of the gastrointestinal tract and is therefore accepted as a biomarker of neutrophil invasion in the gut. This protocol describes an easy, cost-effective kinetic colorimetric assay to quantify myeloperoxidase activity in intestinal tissue samples. It is explained using tissue collected in mice but can also be used for other laboratory animals. In a first step, tissue specimens are homogenized using a phosphate buffer containing 0.5% hexadecyltrimethylammonium bromide (HTAB), which extracts MPO from neutrophils. The obtained supernatant is added to a reagent solution containing o-dianisidine dihydrochloride, which is a peroxidase substrate. Finally, the change in absorption is measured via spectrophotometry and converted to a standardized unit of enzyme activity. The assay is illustrated and compared to a commercially available enzyme-linked immunoassay (ELISA), demonstrating that MPO activity does not necessarily correlate with MPO protein expression in tissue samples. Key features Optimized for use in mice and rats but can also be used for samples of other species. Measures enzymatic activity instead of mRNA or protein expression. Requires a spectrophotometer. Can be performed in duplo using 10 mg of (dry-blotted) gut tissue or more. Graphical overview.

Prevalence, risk factors and diagnostic accuracy of non-invasive tests for NAFLD in people with type 1 diabetes

Background & Aims

The epidemiology of non-alcoholic fatty liver disease (NAFLD) in people with type 1 diabetes (T1D) is not yet elucidated. This study aimed to assess the diagnostic accuracy of non-invasive tests for NAFLD, to investigate the prevalence and severity of NAFLD, and to search for factors contributing to NAFLD in people with T1D.

Methods

In this prospective cohort study, we consecutively screened 530 adults with T1D from a tertiary care hospital, using ultrasound (US), vibration-controlled transient elastography equipped with liver stiffness measurement (LSM) and controlled attenuation parameter, and the fatty liver index. Magnetic resonance spectroscopy (MRS) was performed in a representative subgroup of 132 individuals to validate the diagnostic accuracy of the non-invasive tests.

Results

Based on MRS as reference standard, US identified individuals with NAFLD with an AUROC of 0.98 (95% CI 0.95-1.00, sensitivity: 1.00, specificity: 0.96). The controlled attenuation parameter was also accurate with an AUROC of 0.85 (95% CI 0.77-0.93). Youden cut-off was ≥270 dB/m (sensitivity: 0.90, specificity: 0.74). The fatty liver index yielded a similar AUROC of 0.83 (95% CI 0.74-0.91), but the conventional cut-off used to rule in (≥60) had low sensitivity and specificity (0.62, 0.78). The prevalence of NAFLD in the overall cohort was 16.2% based on US. Metabolic syndrome was associated with NAFLD (OR: 2.35 [1.08-5.12], p = 0.031). The overall prevalence of LSM ≥8.0 kPa indicating significant fibrosis was 3.8%, but reached 13.2% in people with NAFLD.

Conclusions

NAFLD prevalence in individuals with T1D is 16.2%, with approximately one in 10 featuring elevated LSM. US-based screening could be considered in people with T1D and metabolic syndrome.

Impact and Implications

We aimed to report on the prevalence, disease severity, and risk factors of NAFLD in type 1 diabetes (T1D), while also tackling which non-invasive test for NAFLD is the most accurate. We found that ultrasound is the best test to diagnose NAFLD. NAFLD prevalence is 16.2%, and is associated with metabolic syndrome and BMI. Elevated liver stiffness indicating fibrosis is overall not prevalent in people with T1D (3.8%), but it reaches 13.2% in those with T1D and NAFLD.

Risk Factors Associated with Severe RSV Infection in Infants: What Is the Role of Viral Co-Infections?

The respiratory syncytial virus (RSV) represents the leading cause of viral lower respiratory tract infections (LRTI) in children worldwide and is associated with significant morbidity and mortality rates. The clinical picture of an RSV infection differs substantially between patients, and the role of viral co-infections is poorly investigated. During two consecutive winter seasons from October 2018 until February 2020, we prospectively included children up to 2 years old presenting with an acute LRTI, both ambulatory and hospitalized. We collected clinical data and tested nasopharyngeal secretions for a panel of 16 different respiratory viruses with multiplex RT-qPCR. Disease severity was assessed with traditional clinical parameters and scoring systems. A total of 120 patients were included, of which 91.7% were RSV positive; 42.5% of RSV-positive patients had a co-infection with at least one other respiratory virus. We found that patients suffering from a single RSV infection had higher pediatric intensive care unit (PICU) admission rates (OR = 5.9, 95% CI = 1.53 to 22.74), longer duration of hospitalization (IRR = 1.25, 95% CI = 1.03 to 1.52), and a higher Bronchiolitis Risk of Admission Score (BRAS) (IRR = 1.31, 95% CI = 1.02 to 1.70) compared to patients with RSV co-infections. No significant difference was found in saturation on admission, O2 need, or ReSViNET-score. In our cohort, patients with a single RSV infection had increased disease severity compared to patients with RSV co-infections. This suggests that the presence of viral co-infections might influence the course of RSV bronchiolitis, but heterogeneity and small sample size in our study prevents us from drawing strong conclusions. IMPORTANCE RSV is worldwide the leading cause of serious airway infections. Up to 90% of children will be infected by the age of 2. RSV symptoms are mostly mild and typically mimic a common cold in older children and adolescents, but younger children can develop severe lower respiratory tract disease, and currently it is unclear why certain children develop severe disease while others do not. In this study, we found that children with a single RSV infection had a higher disease severity compared to patients with viral co-infections, suggesting that the presence of a viral co-infection could influence the course of an RSV bronchiolitis. As preventive and therapeutic options for RSV-associated disease are currently limited, this finding could potentially guide physicians to decide which patients might benefit from current or future treatment options early in the course of disease, and therefore, warrants further investigation.

IL-22-Activated MUC13 Impacts on Colonic Barrier Function through JAK1/STAT3, SNAI1/ZEB1 and ROCK2/MAPK Signaling

Overexpression of the transmembrane mucin MUC13, as seen in inflammatory bowel diseases (IBD), could potentially impact barrier function. This study aimed to explore how inflammation-induced MUC13 disrupts epithelial barrier integrity by affecting junctional protein expression in IBD, thereby also considering the involvement of MUC1. RNA sequencing and permeability assays were performed using LS513 cells transfected with MUC1 and MUC13 siRNA and subsequently stimulated with IL-22. In vivo intestinal permeability and MUC13-related signaling pathways affecting barrier function were investigated in acute and chronic DSS-induced colitis wildtype and Muc13^-/- mice. Finally, the expression of MUC13, its regulators and other barrier mediators were studied in IBD and control patients. Mucin knockdown in intestinal epithelial cells affected gene expression of several barrier mediators in the presence/absence of inflammation. IL-22-induced MUC13 expression impacted barrier function by modulating the JAK1/STAT3, SNAI1/ZEB1 and ROCK2/MAPK signaling pathways, with a cooperating role for MUC1. In response to DSS, MUC13 was protective during the acute phase whereas it caused more harm upon chronic colitis. The pathways accounting for the MUC13-mediated barrier dysfunction were also altered upon inflammation in IBD patients. These novel findings indicate an active role for aberrant MUC13 signaling inducing intestinal barrier dysfunction upon inflammation with MUC1 as collaborating partner.

Mucin-microbiome signatures shape the tumor microenvironment in gastric cancer

BACKGROUND AND AIMS

We aimed to identify mucin-microbiome signatures shaping the tumor microenvironment in gastric adenocarcinomas and clinical outcomes.

METHODS

We performed high-throughput profiling of the mucin phenotypes present in 108 gastric adenocarcinomas and 20 functional dyspepsia cases using validated mucin-based RT-qPCRs with subsequent immunohistochemistry validation and correlated the data with clinical outcome parameters. The gastric microbiota was assessed by 16S rRNA gene sequencing, taxonomy, and community composition determined, microbial networks analyzed, and the metagenome inferred in association with mucin phenotypes and expression.

RESULTS

Gastric adenocarcinomas with an intestinal mucin environment or high-level MUC13 expression are associated with poor survival. On the contrary, gastric MUC5AC or MUC6 abundance was associated with a more favorable outcome. The oral taxa Neisseria, Prevotella, and Veillonella had centralities in tumors with intestinal and mixed phenotypes and were associated with MUC13 overexpression, highlighting their role as potential drivers in MUC13 signaling in GC. Furthermore, dense bacterial networks were observed in intestinal and mixed mucin phenotype tumors whereas the lowest community complexity was shown in null mucin phenotype tumors due to higher Helicobacter abundance resulting in a more decreased diversity. Enrichment of oral or intestinal microbes was mucin phenotype dependent. More specifically, intestinal mucin phenotype tumors favored the establishment of pro-inflammatory oral taxa forming strong co-occurrence networks.

CONCLUSIONS

Our results emphasize key roles for mucins in gastric cancer prognosis and shaping microbial networks in the tumor microenvironment. Specifically, the enriched oral taxa associated with aberrant MUC13 expression can be potential biomarkers in predicting disease outcomes. Video Abstract.

Single-day and multi-day exposure to orogastric gavages does not affect intestinal barrier function in mice

Animals involved in common laboratory procedures experience minor levels of stress. The direct effect of limited amounts of stress on gastrointestinal function has not been reported yet. Therefore, this study aimed to assess the effect of single-day and multi-day orogastric gavages on gut physiology in mice. To this end, 12-wk-old female C57Bl6/J mice were randomized to receive treatment with sterile water (200 µL) delivered by orogastric gavages twice daily for a total of 1 or 10 day(s). Control animals did not receive any treatment. Subsequently, gastrointestinal function was assessed by measuring fecal pellet production. Furthermore, ex vivo intestinal barrier and secretory function of the distal colon, proximal colon, and terminal ileum were quantified in Ussing chambers. In mice, single-day gavages did neither influence corticosterone levels nor gastrointestinal function. In mice exposed to multi-day gavages, corticosterone levels were slightly but significantly increased compared with controls after 10 days of treatment. Gastrointestinal motor function was altered, as evidenced by increased fecal pellet counts and a small increase in fecal water content. However, exposure to repeated gavages did not lead to detectable alterations in gastrointestinal barrier function as quantified by the paracellular flux of the probe 4 kDa FITC-dextran as well as transepithelial resistance measurements. Thus, the administration of drugs via single-day or multi-day orogastric gavages leads to no or minor stress in mice, respectively. In both cases, it does not hamper the study of the intestinal barrier function and therefore remains a valuable administration route in preclinical pharmacological research.NEW & NOTEWORTHY Exposure of mice to serial orogastric gavages over the course of 10 days leads to a small but significant increase in plasma corticosterone levels, indicating the presence of a limited amount of stress that is absent after a single-day treatment. This minor stress after multi-day gavages results in increased fecal pellet production and fecal water content in exposed compared with nontreated mice but does not affect the intestinal barrier function in the distal colon, proximal colon, or terminal ileum.

Urinary epidermal growth factor reflects vascular health in boys with either obesity or type 1 diabetes. A role for renin, or beyond?

An increased blood pressure is a known comorbidity of both type 1 diabetes (T1DM) and obesity in children. Increasing evidence suggests a subtle interplay between epidermal growth factor (EGF) and renin along the juxtaglomerular system, regulating the impact of blood pressure on kidney health and the cardiovascular system. In this study, we investigated the relation between urinary EGF, serum renin and blood pressure in children with obesity or T1DM. 147 non-obese children with T1DM and 126 children with obesity, were included. Blood pressure was measured and mean arterial pressure (MAP) and the pulse pressure (PP) were calculated. Serum renin and urinary EGF levels were determined with a commercial ELISA kit. Partial Spearman rank correlation coefficients and multiple linear regression models were used to study the association between renin, the urinary EGF/urinary creatinine ratio and blood pressure parameters. The urinary EGF/urinary creatinine ratio is correlated with the SBP and the MAP in boys with obesity as well as in boys with T1DM. Multiple regression analysis showed that sex and pulse pressure in male subjects were found to be independently associated with renin. Sex, the presence of diabetes, age, the glomerular filtration rate and both pulse pressure and mean arterial pressure in male subjects were independently associated with urinary EGF/urinary creatinine. In conclusion, in boys with either obesity or diabetes, pulse pressure and mean arterial pressure are negatively associated with the functional integrity of the nephron, which is reflected by a decreased expression of urinary EGF.

Volatile organic compound profiling as a potential biomarker in irritable bowel syndrome: A feasibility study

Background

Irritable bowel syndrome (IBS) is a chronic gastrointestinal disorder for which no diagnostic tools are currently available. Patients are diagnosed using the Rome IV criteria and subtyped into a diarrhea, constipation, or mixed phenotype based on their dominant stool pattern. A recent development in the biomarker area is the analysis of volatile organic compounds (VOCs). The aim of this study was to evaluate the potential of VOCs as diagnostic and phenotypic biomarkers for IBS in breath and fecal samples.

Materials and methods

Breath and fecal samples from IBS patients and healthy asymptomatic controls (HC) were analyzed with multicapillary column/ion mobility spectrometry (MCC/IMS) and classification models were created based upon VOCs and clinical characteristics.

Discussion

Irritable bowel syndrome patients were differentiated from HC by means of volatile profiling in both breath and fecal samples with area under the curve (AUCs) of respectively 0.62 and 0.80. Patient subtypes could also be differentiated from each other with AUCs ranging between 0.65 and 0.78. Furthermore, VOC models could differentiate IBS patients based on clinical characteristics like psychological comorbidities and microbiota-influencing therapies.

Conclusion

This study is the first to demonstrate the use of VOC profiling with the help of MCC/IMS to differentiate IBS patients. Furthermore, the importance of clinical characteristics beside the dominant stool pattern in the differentiation of IBS patients was emphasized.

SARS-CoV-2 mRNA vaccination is not associated with the induction of anti-HLA or non-HLA antibodies

BACKGROUND

SARS-CoV-2 vaccination is strongly recommended in kidney transplant recipients (KTR) and dialysis patients. Whether these vaccinations may trigger alloantibodies, is still debated.

METHODS

In the current study we evaluated the effect of SARS-CoV-2 mRNA vaccines on anti-Human Leukocyte Antigen (HLA) and 60 anti-non-HLA antibody profiles in clinically stable KTR and dialysis patients. In total, we included 28 KTR, 30 patients on haemodialysis, 25 patients on peritoneal dialysis and 31 controls with a positive seroresponse 16-21 days after the first dose of either the SARS-CoV-2 mRNA BNT162b2 or mRNA-1273 vaccine. Both anti-HLA and anti-non-HLA antibodies were determined prior to vaccination and 21 to 35 days after the second vaccine dose.

RESULTS

Overall, the proportion of patients with detectable anti-HLA antibodies was similar before and after vaccination (class I 14% vs. 16%, p = 0.48; class II 25% before and after vaccination). After vaccination, there was no pattern in 1) additionally detected anti-HLA antibodies, or 2) the levels of pre-existing ones. Additional anti-non-HLA antibodies were detected in 30% of the patients, ranging from 1 to 5 new anti-non-HLA antibodies per patient. However, the clinical significance of anti-non-HLA antibodies is still a matter of debate. To date, only a significant association has been found for anti-non-HLA ARHGDIB antibodies and long-term kidney graft loss. No additionally developed anti-ARHGDIB antibodies or elevated level of existing anti-ARHGDIB antibodies was observed.

CONCLUSION

The current data indicate that SARS-CoV-2 mRNA vaccination does not induce anti-HLA or anti-non-HLA antibodies, corroborating the importance of vaccinating KTR and dialysis patients.

The Effect of Serine Protease Inhibitors on Visceral Pain in Different Rodent Models With an Intestinal Insult

Background: Serine proteases are believed to play a key role in the origin of abdominal pain in IBD and IBS. We previously demonstrated a reduction of visceral pain in a post-inflammatory IBS rat model after a single intraperitoneal or intracolonic administration of a serine protease inhibitor. The aim of this study was to investigate the efficacy of serine protease inhibition on visceral pain in two different animal models involving a colonic insult based either on acute inflammation or on neonatal irritation. Moreover, protease profiling was explored in the acute colitis model. Methods: An acute 2,4,6-trinitrobenzenesulphonic acid (TNBS) colitis rat model and a chronic neonatal acetic acid mouse model were used in this study. Visceral sensitivity was quantified by visceromotor responses (VMRs) to colorectal distension, 30 min after intraperitoneal administration of the serine protease inhibitors nafamostat, UAMC-00050 or their vehicles. Colonic samples from acute colitis rats were used to quantify the mRNA expression of a panel of serine proteases and mast cell tryptase by immunohistochemistry. Finally, proteolytic activities in colonic and fecal samples were characterized using fluorogenic substrates. Key Results: We showed a significant and pressure-dependent increase in visceral hypersensitivity in acute colitis and neonatal acetic acid models. UAMC-00050 and nafamostat significantly reduced VMRs in both animal models. In acute colitis rats, the administration of a serine protease inhibitor did not affect the inflammatory parameters. Protease profiling of these acute colitis animals revealed an increased tryptase immunoreactivity and a downregulation of matriptase at the mRNA level after inflammation. The administration of UAMC-00050 resulted in a decreased elastase-like activity in the colon associated with a significantly increased elastase-like activity in fecal samples of acute colitis animals. Conclusion: In conclusion, our results suggest that serine proteases play an important role in visceral hypersensitivity in an acute TNBS colitis model in rats and a neonatal acetic acid model in mice. Moreover, we hypothesize a potential mechanism of action of UAMC-00050 via the alteration of elastase-like proteolytic activity in acute inflammation. Taken together, we provided fundamental evidence for serine protease inhibitors as a promising new therapeutic strategy for abdominal pain in gastrointestinal diseases.

Does peer teaching improve academic results and competencies during medical school? A mixed methods study

BACKGROUND

This study investigates the impact of Peer-Assisted Learning (PAL) in clinical skills on peer teachers' academic scores and competencies; however, controversy remains on this topic, and concrete evidence on its impact lacking.

METHODS

We performed a mixed methods study combining a retrospective cohort study with a modified Delphi survey. Peer teachers and Skills Lab faculty members participated in this study. A validated questionnaire, the CanMEDS Competency Based Inventory (CCBI), and group interviews were used to assess the outcomes of PAL. Our results were also triangulated with literature data.

RESULTS

In 3 consecutive cohorts of medical students (n = 311), 78 participated in PAL. Peer teachers obtained higher scores from the start of the study, at different timepoints in medical school, and on their final scores compared to all other students. Interestingly their progress followed the same path and magnitude as other well-performing students. However, based on our findings from a modified Delphi survey (CCBI interviews) and a literature review, we found further supporting evidence for a positive impact of PAL on the competencies of physical skills (medical expert), teamwork and leadership (collaborator), lifelong learning (scholar), and for admitting uncertainty/limits (professional) within the CanMEDS roles.

CONCLUSIONS

We conclude that higher achieving students are more likely to volunteer for a peer tutoring program; however this does not significantly augment their academic scores as compared to above well-performing non-teaching fellow students. Importantly, our modified Delphi survey indicated which CanMEDS roles were positively impacted by PAL: medical expert, collaborator, scholar and professional.

Seroconversion rate after primary vaccination with two doses of BNT162b2 versus mRNA-1273 in solid organ transplant recipients: a systematic review and meta-analysis

Background

In the general population, the seroconversion rate after primary vaccination with two doses of an anti-severe acute respiratory syndrome coronavirus 2 messenger RNA (mRNA) vaccine reaches nearly 100%, with significantly higher antibody titers after mRNA-1273 vaccination compared to BNT162b2 vaccination. Here we performed a systematic review and meta-analysis to compare the antibody response after two-dose mRNA-1273 versus BNT162b2 vaccination in solid organ transplant (SOT) recipients.

Methods

A systematic literature review was performed using PubMed, Web of Science and the Cochrane Library and original research papers were included for a meta-analysis to calculate vaccine-specific seroconversion rates for each of the mRNA vaccines. Next, the pooled relative seroconversion rate was estimated.

Results

Eight studies that described the development of antibodies against receptor-binding domain (RBD) and/or spike protein were eligible for meta-analysis. Two of these studies also reported antibody titers. The meta-analysis revealed lower seroconversion rates in SOT recipients vaccinated with two doses of BNT162b2 {44.3% [95% confidence interval (CI) 34.1–54.7]} as compared with patients vaccinated with two doses of mRNA-1273 [58.4% (95% CI 47.2–69.2)]. The relative seroconversion rate was 0.795 (95% CI 0.732–0.864).

Conclusions

This systematic review and meta-analysis indicates that in SOT recipients, higher seroconversion rates were observed after vaccination with mRNA-1273 compared with BNT162b2.

The Role of Brain-Derived Neurotrophic Factor in Obstructive Sleep Apnea and Endothelial Function in a Pediatric Population With Obesity

BACKGROUND

Childhood obesity has increased worldwide, becoming a significant public health concern. Brain-derived neurotrophic factor (BDNF) plays an important role in the central regulation of food intake and body weight, but little is known regarding its role in childhood obesity. Next to obesity, BDNF has been linked to obstructive sleep apnea (OSA) and endothelial dysfunction, two obesity-related comorbidities. The aim of this study is to investigate how BDNF, OSA and endothelial dysfunction interact in children with obesity and to determine the effect of weight loss on serum BDNF levels.

METHODS

Children and adolescents with obesity aged 8-18 years who were enrolled in a multidisciplinary obesity treatment (MOT) in a tertiary hospital, were prospectively included. Several examinations were conducted during this MOT; at baseline, after 6 months and after 12 months, including the assessment of endothelial function, body composition measurements and a polysomnography. BDNF levels were measured on a serum sample by means of ELISA.

RESULTS

A total of 103 patients with obesity was included, of which 20 had OSA (19.4%). BDNF levels were comparable in children with obesity and OSA and children with obesity but without OSA (26.75 vs. 27.87 ng/ml, p = 0.6). No correlations were found between BDNF and sleep-related variables or between BDNF and endothelial function parameters nor between BDNF and adiposity measures. To investigate if the interaction between OSA and endothelial dysfunction had an influence on BDNF levels, a general linear model was used. This model revealed that a diagnosis of OSA, as well as the interaction between OSA and maximal endothelial dilatation, contributed significantly (p = 0.03, p = 0.04, respectively) to BDNF levels. After 1 year of weight loss therapy, BDNF levels did not change (26.18 vs. 25.46 ng/ml, p = 0.7) in our population.

CONCLUSION

BDNF concentrations were comparable in children with obesity, both with and without OSA, indicating that BDNF levels are not affected by OSA. However, we did find an interaction effect of OSA and endothelial function on BDNF levels.

A dynamic mucin mRNA signature associates with COVID-19 disease presentation and severity

BACKGROUND

SARS-CoV-2 infection induces mucin overexpression, further promoting disease. Given that mucins are critical components of innate immunity, unraveling their expression profiles that dictate the course of disease could greatly enhance our understanding and management of COVID-19.

METHODS

Using validated RT-PCR assays, we assessed mucin mRNA expression in the blood of patients with symptomatic COVID-19 compared with symptomatic patients without COVID-19 and healthy controls and correlated the data with clinical outcome parameters. Additionally, we analyzed mucin expression in mucus and lung tissue from patients with COVID-19 and investigated the effect of drugs for COVID-19 treatment on SARS-CoV-2–induced mucin expression in pulmonary epithelial cells.

RESULTS

We identified a dynamic blood mucin mRNA signature that clearly distinguished patients with symptomatic COVID-19 from patients without COVID-19 based on expression of MUC1, MUC2, MUC4, MUC6, MUC13, MUC16, and MUC20 (AUC_ROC of 91.8%; sensitivity and specificity of 90.6% and 93.3%, respectively) and that discriminated between mild and critical COVID-19 based on the expression of MUC16, MUC20, and MUC21 (AUC_ROC of 89.1%; sensitivity and specificity of 90.0% and 85.7%, respectively). Differences in the transcriptional landscape of mucins in critical cases compared with mild cases identified associations with COVID-19 symptoms, respiratory support, organ failure, secondary infections, and mortality. Furthermore, we identified different mucins in the mucus and lung tissue of critically ill COVID-19 patients and showed the ability of baricitinib, tocilizumab, favipiravir, and remdesivir to suppress expression of SARS-CoV-2–induced mucins.

CONCLUSION

This multifaceted blood mucin mRNA signature showed the potential role of mucin profiling in diagnosing, estimating severity, and guiding treatment options in patients with COVID-19.

FUNDING

The Antwerp University Research and the Research Foundation Flanders COVID-19 funds.

Proteolytic Cleavage of Bioactive Peptides and Protease-Activated Receptors in Acute and Post-Colitis

The protease activity in inflammatory bowel disease (IBD) and irritable bowel syndrome has been studied extensively using synthetic fluorogenic substrates targeting specific sets of proteases. We explored activities in colonic tissue from a 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis rat model by investigating the cleavage of bioactive peptides. Pure trypsin- and elastase-like proteases on the one hand and colonic tissue from rats with TNBS-induced colitis in the acute or post-inflammatory phase on the other, were incubated with relevant peptides to identify their cleavage pattern by mass spectrometry. An increased cleavage of several peptides was observed in the colon from acute colitis rats. The tethered ligand (TL) sequences of peptides mimicking the N-terminus of protease-activated receptors (PAR) 1 and 4 were significantly unmasked by acute colitis samples and these cleavages were positively correlated with thrombin activity. Increased cleavage of β-endorphin and disarming of the TL-sequence of the PAR3-based peptide were observed in acute colitis and linked to chymotrypsin-like activity. Increased processing of the enkephalins points to the involvement of proteases with specificities different from trypsin- or chymotrypsin-like enzymes. In conclusion, our results suggest thrombin, chymotrypsin-like proteases and a set of proteases with different specificities as potential therapeutic targets in IBD.

Improving Self-Reflection Assessment Practices: Comparative Judgment as an Alternative to Rubrics

CONSTRUCT

The authors aimed to investigate the utility of the comparative judgment method for assessing students' written self-reflections.

BACKGROUND

Medical practitioners' reflective skills are increasingly considered important and therefore included in the medical education curriculum. However, assessing students' reflective skills using rubrics does not appear to guarantee adequate inter-rater reliabilities. Recently, comparative judgment was introduced as a new method to evaluate performance assessments. This study investigates the merits and limitations of the comparative judgment method for assessing students' written self-reflections. More specifically, it examines the reliability in relation to the time spent assessing, the correlation between the scores obtained using the two methods (rubrics and comparative judgment), and, raters' perceptions of the comparative judgment method.

APPROACH

Twenty-two self-reflections, that had previously been scored using a rubric, were assessed by a group of eight raters using comparative judgment. Two hundred comparisons were completed and a rank order was calculated. Raters' impressions were investigated using a focus group.

FINDINGS

Using comparative judgment, each self-reflection needed to be compared seven times with another self-reflection to reach a scale separation reliability of .55. The inter-rater reliability of rating (ICC, (1, k)) using rubrics was .56. The time investment required for these reliability levels in both methods was around 24 minutes. The Kendall's tau rank correlation indicated a strong correlation between the scores obtained via both methods. Raters reported that making comparisons made them evaluate the quality of self-reflections in a more nuanced way. Time investment was, however, considered heavy, especially for the first comparisons. Although raters appreciated that they did not have to assign a grade to each self-reflection, the fact that the method does not automatically lead to a grade or feedback was considered a downside.

CONCLUSIONS

First evidence was provided for the comparative judgment method as an alternative to using rubrics for assessing students' written self-reflections. Before comparative judgment can be implemented for summative assessment, more research is needed on the time investment required to ensure no contradictory feedback is given back to students. Moreover, as the comparative judgment method requires an additional standard setting exercise to obtain grades, more research is warranted on the merits and limitations of this method when a pass/fail approach is used.

The impact of obstructive sleep apnea on endothelial function during weight loss in an obese pediatric population

BACKGROUND

Childhood obesity is an increasing problem with substantial comorbidities such as obstructive sleep apnea (OSA) and increased cardiovascular morbidity. Endothelial dysfunction is an underlying mechanism related to both obesity and OSA.

RESEARCH QUESTION

To investigate the effect of weight loss on endothelial function and OSA in obese children and to determine whether a change in endothelial function can be linked to an improvement in OSA.

METHODS

Obese children between 8 and 18 years of age were recruited while entering a 12-month inpatient weight loss program. Patients were followed at 3 study visits: baseline, after 10 months of weight loss, and 6 months after ending the program (18 months). Anthropometry and endothelial function (EndoPAT) were determined at all study visits. At baseline, sleep screening with a portable device (ApneaLink) was performed. This was repeated after 10 months if OSA was diagnosed at baseline.

RESULTS

At baseline, 130 children were included, of which 87 had OSA (67%). Seventy-two patients attended the follow-up visit at 10 months, and 28 patients attended the follow-up visit at 18 months. The BMI z-score decreased after 10 months (from 2.7 (1.4-3.4) to 1.7 (0.5-2.7); p < 0.001) and remained stable at 18 months. Endothelial function improved significantly after weight loss, evidenced by a shorter time to peak response (TPR) and higher reactive hyperemia index (p = 0.02 and p < 0.001), and remained improved after 18 months (p < 0.001 and p = 0.007). After 10 months of weight loss, 10 patients had residual OSA. These patients had a higher TPR at 10 months (225 (75-285)s) than those without OSA (135 (45-225)s) and patients with a normalized sleep study (105 (45-285)s; p = 0.02). Linear mixed models showed that more severe OSA was associated with a worse TPR at baseline and less improvement after weight loss.

CONCLUSION

Weight loss improves endothelial function in an obese pediatric population. However, even after weight loss, endothelial function improved less in the presence of OSA.

The next generation: Urinary epidermal growth factor is associated with an early decline in kidney function in children and adolescents with type 1 diabetes mellitus

AIMS

Micro-albuminuria is considered an early clinical sign of diabetes nephropathy, however, early decrease of glomerular filtration can be present years before the presence of microalbuminuria. In this study, we explored whether urinary epidermal growth factor (uEGF) might serve as an early marker of diabetes nephropathy compared to microalbuminuria in children and adolescents.

METHODS

Children with type 1 diabetes mellitus (n = 158) and healthy controls (n = 40) were included in this study. Serum and urine samples were collected three times with an interval of at least one month to determine creatinine (serum and urine), epidermal growth factor and albumin (urine). Demographic data and routine lab values were extracted out of the electronic patient files.

RESULTS

uEGF was significantly lower in children with T1DM compared to healthy controls (p = 0.032). A relatively lower glomerular filtration rate (eGFR) was associated with a decreased uEGF (p < 0.001). uEGF was independently associated with eGFR in a multivariate analysis.

CONCLUSION

This study provides evidence that uEGF can serve as an early marker of diabetes nephropathy in children and adolescents.

The Effect of a Novel Serine Protease Inhibitor on Inflammation and Intestinal Permeability in a Murine Colitis Transfer Model

Background: A protease/antiprotease disbalance is observed in inflammatory bowel diseases (IBD). We therefore studied the effect of the novel serine protease inhibitor UAMC-00050 on intestinal inflammation and permeability in a chronic colitis T cell transfer mouse model to get further insight into the regulation of T cell-mediated immunopathology. Methods: Colitis was induced in severe combined immunodeficient (SCID) mice, by the adoptive transfer of CD4⁺CD25^-CD62L⁺ T cells. Animals were treated intraperitoneally (i.p.) 2x/day with vehicle or UAMC-00050 (5 mg/kg) from week 2 onwards. Colonic inflammation was assessed by clinical parameters, colonoscopy, macroscopy, microscopy, myeloperoxidase activity and cytokine expression levels. At week 4, 4 kDa FITC-dextran intestinal permeability was evaluated and T helper transcription factors, protease-activated receptors and junctional proteins were quantified by RT-qPCR. Results: Adoptive transfer of CD4⁺CD25^-CD62L⁺ T cells resulted in colonic inflammation and an altered intestinal permeability. The serine protease inhibitor UAMC-00050 ameliorated both the inflammatory parameters and the intestinal barrier function. Furthermore, a decrease in colonic mRNA expression of Tbet and PAR4 was observed in colitis mice after UAMC-00050 treatment. Conclusion: The beneficial effect of UAMC-00050 on inflammation was apparent via a reduction of Tbet, IFN-γ, TNF-α, IL-1β and IL-6. Based on these results, we hypothesize a pivotal effect of serine protease inhibition on the Th1 inflammatory profile potentially mediated via PAR4.

Epidermal growth factor as a potential prognostic and predictive biomarker of response to platinum-based chemotherapy

In this study, we investigated serum epidermal growth factor (EGF) in an oncological population of head- and neck and pulmonary neoplasms and whether serum EGF could serve as a prognostic marker of survival and as a predictive marker for treatment response to platinum-based chemotherapy. A total of 59 oncological patients and a control group of age- and sex-matched healthy volunteers were included in this study. Pre-treatment serum EGF from both groups was determined. Patient’s and tumour characteristics and mortality were recorded during a 5-year follow up period. Baseline serum EGF significantly differed between the oncological patients and the healthy volunteers (p<0.001). Serum EGF was associated with lymph node metastasis (p = 0.004) but not with sex (p = 0.753), age (p = 1.00), TNM stage (p = 0.191) or tumour size (p = 0.077). Neither serum EGF (p = 0.81) nor age (p = 0.55) showed an effect on the patient’s survival. Tumour location was significantly associated with overall 5-year survival (p = 0.003). The predictive capacity of serum EGF of response to chemotherapy was limited (AUC = 0.606), a sensitivity of 80% and a specificity of 56% was observed resulting in a likelihood ratio of a positive and negative test equal to 1.81 and 0.36, respectively. In conclusion, serum EGF levels are 5.5 times higher in an oncological population compared to a control group. Within the oncological population, low serum EGF values are associated with the presence of lymph node metastasis. Further investigation is necessary to determine if the serum EGF levels could serve as a diagnostic biomarker.

Functional respiratory imaging provides novel insights into the long-term respiratory sequelae of bronchopulmonary dysplasia

RATIONALE

Bronchopulmonary dysplasia (BPD) is a common complication of preterm birth. Lung function and imaging are classically used to assess BPD. Functional respiratory imaging (FRI) combines a structural and functional assessment of the airways and their vasculature. We aimed to assess BPD using FRI and to correlate these findings with the clinical presentation.

METHODS

We included 37 adolescents with a history of preterm birth (22 BPD cases and 15 preterm controls). The study protocol included a detailed history, lung function testing and computed tomography (CT) (at total lung capacity (TLC) and functional residual capacity (FRC)) with FRI. CT images were also assessed using the Aukland scoring system.

RESULTS

BPD patients had lower forced expiratory volume in 1 s to forced vital capacity ratio (p=0.02) and impaired diffusion capacity (p=0.02). Aukland CT scores were not different between the two groups. FRI analysis showed higher lobar volumes in BPD patients at FRC (p<0.01), but not at TLC. Airway resistance was significantly higher in the BPD group, especially in the distal airways. Additionally, FRI showed more air trapping in BPD patients, in contrast to findings on conventional CT images.

CONCLUSION

This study is the first to use FRI in research for BPD. FRI analysis showed higher lobar volumes in BPD patients, indicating air trapping and reduced inspiratory capacity. In contrast to Aukland CT scores, FRI showed more air trapping in the BPD group, suggesting that FRI might be a more sensitive detection method. Importantly, we also showed increased distal airway resistance in BPD patients. By combining structural and functional assessment, FRI may help to better understand the long-term sequelae of BPD.

Local Colonic Administration of a Serine Protease Inhibitor Improves Post-Inflammatory Visceral Hypersensitivity in Rats

Dysregulation of the protease–antiprotease balance in the gastrointestinal tract has been suggested as a mechanism underlying visceral hypersensitivity in conditions such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). We aimed to study the potential therapeutic role of an intracolonically administered serine protease inhibitor for the treatment of abdominal pain in a post-inflammatory rat model for IBS. An enema containing 2,4,6-trinitrobenzene sulfonic acid (TNBS) was used to induce colitis in male Sprague–Dawley rats, whereas controls received a saline solution. Colonoscopies were performed to confirm colitis and follow-up mucosal healing. In the post-inflammatory phase, the serine protease inhibitor UAMC-00050 (0.1–5 mg/kg) or its vehicle alone (5% DMSO in H₂O) was administered in the colon. Thirty minutes later, visceral mechanosensitivity to colorectal distensions was quantified by visceromotor responses (VMRs) and local effects on colonic compliance and inflammatory parameters were assessed. Specific proteolytic activities in fecal and colonic samples were measured using fluorogenic substrates. Pharmacokinetic parameters were evaluated using bioanalytical measurements with liquid chromatography–tandem mass spectrometry. Post-inflammatory rats had increased trypsin-like activity in colonic tissue and elevated elastase-like activity in fecal samples compared to controls. Treatment with UAMC-00050 decreased trypsin-like activity in colonic tissue of post-colitis animals. Pharmacokinetic experiments revealed that UAMC-00050 acted locally, being taken up in the bloodstream only minimally after administration. Local administration of UAMC-00050 normalized visceral hypersensitivity. These results support the role of serine proteases in the pathophysiology of visceral pain and the potential of locally administered serine protease inhibitors as clinically relevant therapeutics for the treatment of IBS patients with abdominal pain.

Intestinal barrier dysfunction in irritable bowel syndrome: a systematic review

BACKGROUND AND AIM

Irritable bowel syndrome (IBS) is a complex and heterogeneous disorder. Sensory, motor and barrier dysfunctions are the key physiological endophenotypes of IBS. Our aim is to review studies evaluating barrier dysfunction in adults and children with IBS, as well as to link those changes with IBS symptomatology and quality of life.

METHODS

A comprehensive and systematic review of multiple databases was performed up to March 2020 to identify studies comparing intestinal permeability in IBS patients with healthy controls. Both in vivo and in vitro studies were considered.

RESULTS

We identified 66 studies, of which 27 used intestinal probes to quantify barrier function. The prevalence of barrier dysfunction differed between PI-IBS (17-50%), IBS-D (37-62%) and IBS-C (4-25%). At a group level, permeability was increased compared with healthy controls in IBS-D (9/13 studies) and PI-IBS (4/4 studies), but only a minority of IBS-C (2/7 studies) and not in the only IBS-M study. All four studies in children with IBS demonstrated loss of barrier function. A heterogeneous set of tight junction genes were found to be altered in small and large intestines of adults with IBS, but these have not been evaluated in children. Positive associations were identified between barrier dysfunction and bowel disturbances (6/9 studies), abdominal pain (9/13 studies), overall symptom severity (1/6 studies), depression and anxiety (1/1 study) and quality of life (1/4 studies). Fecal slurry or supernatants of IBS patients were found to induce barrier disruption in animal models (5/6 studies).

CONCLUSIONS

Barrier dysfunction is present in a significant proportion of adult and all pediatric IBS studies, especially in the IBS-D and PI-IBS subtype. The majority of studies indicated a positive association between loss of barrier function and symptoms such as abdominal pain and changes in the bowel function.

Improving Treatment Outcome in Children With Obesity by an Online Self-Control Training: A Randomized Controlled Trial

Background: Currently available treatment programs for children with obesity only have modest long-term results, which is (at least partially) due to the poorer self-control observed within this population. The present trial aimed to determine whether an online self-control training, training inhibition, and redirecting attentional bias, can improve the short- and long-term treatment outcome of (in- or outpatient) child obesity treatment programs. Methods: In this double-blind multi-center randomized controlled trial (RCT), participants aged 8-18 years with obesity were allocated in a 1:1 ratio to receive an online self-control or sham training added to their in- or outpatient multidisciplinary obesity treatment (MOT) program. The primary endpoint was BMI SDS. Data were analyzed by linear mixed models and the main interactions of interest were randomization by time and randomization by number of sessions, as the latter was cumulatively expressed and therefore represents the effect of increasing dose over time. Results: One hundred forty-four inpatient (mean age 14.3 ± 2.2 years, BMI 2.7 ± 0.4 SDS, 42% male) and 115 outpatient children (mean age 11.9 ± 2.1 years, BMI 2.4 ± 0.4 SDS, 45% male) were included. Children's BMI lowered significantly during treatment in both the in- and outpatient treatment centers, p < 0.001. In a mixed model with BMI as dependent variable, randomization by time was non-significant, but the number of self-control trainings (randomization ^* number of sessions) interacted significantly with setting and with age (p = 0.002 and p = 0.047), indicating a potential effect in younger inpatient residents. Indeed, a subgroup analysis on 22 inpatient children of 8-12 years found a benefit of the number of self-control trainings on BMI (p = 0.026). Conclusions: The present trial found no benefit of the self-control training in the entire study population, however a subgroup of young, inpatient participants potentially benefited.

Body composition monitoring in children and adolescents: reproducibility and reference values

There is an increasing need for suitable tools to evaluate body composition in paediatrics. The Body Composition Monitor (BCM) shows promise as a method, but reference values in children are lacking. Twenty children were included and measured twice by 4 different raters to asses inter- and intra-rater reproducibility of the BCM. Reliability was assessed using the Bland-Altman method and by calculating intraclass correlation coefficients (ICCs). The intra-rater ICCs were high (≥ 0.97) for all parameters measured by BCM as were the inter-rater ICCs for all parameters (≥ 0.98) except for overhydration (0.76). Consequently, a study was set up in which BCM measurements were performed in 2058 healthy children aged 3-18.5 years. The age- and gender-specific percentile values and reference curves for body composition (BMI, waist circumference, fat mass and lean tissue mass) and fluid status (extracellular and intracellular water and total body water) relative to age were produced using the GAMLSS method for growth curves.Conclusion: A high reproducibility of BCM measurements was found for fat mass, lean tissue mass, extracellular water and total body water. Reference values for these BCM parameters were calculated in over 2000 children and adolescents aged 3 to 18 years. What is Known • The 4-compartment model is regarded as the 'gold standard' of body composition methods, but is inappropriate for regular follow-up or screening of large groups, because of associated limitations. • Body Composition Monitor® is an inexpensive field method that has the potential to be an adequate monitoring tool. What is New • Good reproducibility of BCM measurements in children provides evidence to use the device in longitudinal follow-up, multicentre and comparative studies. • Paediatric reference values relative to age and sex for the various compartments of the body are provided.

The use of plasma donor-derived, cell-free DNA to monitor acute rejection after kidney transplantation

BACKGROUND

After transplantation, cell-free deoxyribonucleic acid (DNA) derived from the donor organ (ddcfDNA) can be detected in the recipient's circulation. We aimed to investigate the role of plasma ddcfDNA as biomarker for acute kidney rejection.

METHODS

From 107 kidney transplant recipients, plasma samples were collected longitudinally after transplantation (Day 1 to 3 months) within a multicentre set-up. Cell-free DNA from the donor was quantified in plasma as a fraction of the total cell-free DNA by next generation sequencing using a targeted, multiplex polymerase chain reaction-based method for the analysis of single nucleotide polymorphisms.

RESULTS

Increases of the ddcfDNA% above a threshold value of 0.88% were significantly associated with the occurrence of episodes of acute rejection (P = 0.017), acute tubular necrosis (P = 0.011) and acute pyelonephritis (P = 0.032). A receiver operating characteristic curve analysis revealed an equal area under the curve of the ddcfDNA% and serum creatinine of 0.64 for the diagnosis of acute rejection.

CONCLUSIONS

Although increases in plasma ddcfDNA% are associated with graft injury, plasma ddcfDNA does not outperform the diagnostic capacity of the serum creatinine in the diagnosis of acute rejection.

Donor-derived cell-free DNA as a biomarker for rejection after kidney transplantation: a systematic review and meta-analysis

A systematic review and meta-analysis were performed to investigate the value of donor-derived cell-free DNA (dd-cfDNA) as a noninvasive biomarker in diagnosing kidney allograft rejection. We searched PubMed, Web of Science and the Cochrane Library for original research papers published between January 1994 and May 2020 on dd-cfDNA fractions in blood of kidney allograft recipients. A single-group meta-analysis was performed by computing pooled estimates for dd-cfDNA fractions using the weighted median of medians or quantile estimation (QE) approach. Weighted median differences in medians (WMDMs) and median differences based on the QE method were used for pairwise comparisons. Despite heterogeneity among the selected studies, the meta-analysis revealed significantly higher median dd-cfDNA fractions in patients with antibody-mediated rejection (ABMR) than patients without rejection or patients with stable graft function. When comparing patients with T cell-mediated rejection (TCMR) and patients with ABMR, our two statistical approaches revealed conflicting results. Patients with TCMR did not have different median dd-cfDNA fractions than patients without rejection or patients with stable graft function. dd-cfDNA may be a useful marker for ABMR, but probably not for TCMR.

Adoptive Cell Transfer of Regulatory T Cells Exacerbates Hepatic Steatosis in High-Fat High-Fructose Diet-Fed Mice

Background and Aims: Non-alcoholic steatohepatitis (NASH) is a multisystem condition, involving the liver, adipose tissue, and immune system. Regulatory T (Treg) cells are a subset of T cells that exert an immune-controlling effect. Previously, a reduction of Treg cells in the visceral adipose tissue (VAT) was shown to be associated with a more severe degree of liver disease. We aimed to correct this immune disruption through adoptive cell transfer (ACT) of Treg cells. Methods: Male 8-week-old C57BL/6J mice were fed a high-fat high-fructose diet (HFHFD) for 20 weeks. Treg cells were isolated from the spleens of healthy 8 to 10-week-old C57BL/6J mice and were adoptively transferred to HFHFD-fed mice. PBS-injected mice served as controls. Plasma ALT and lipid levels were determined. Liver and adipose tissue were assessed histologically. Cytotoxic T (Tc), Treg, T helper (Th) 1 and Th17 cells were characterized in VAT, liver, subcutaneous adipose tissue (SAT), blood, and spleen via flow cytometry. Gene expression analysis was performed in SAT and VAT of mice fed either the HFHFD or a control diet for 10-32 weeks. Results: ACT increased Treg cells in SAT, but not in any of the other tissues. Moreover, the ACT induced a decrease in Th1 cells in SAT, liver, blood, and spleen. Higher plasma ALT levels and a higher degree of steatosis were observed in ACT mice, whereas the other HFHFD-induced metabolic and histologic disruptions were unaffected. Expression analysis of genes related to Treg-cell proliferation revealed a HFHFD-induced decrease in all investigated genes in the SAT, while in the VAT the expression of these genes was largely unaffected, except for a decrease in Pparg. Conclusion: ACT of Treg cells in HFHFD-fed mice exacerbated hepatic steatosis, which was possibly related to the increase of Treg cells in the SAT and/or the general decrease in Th1 cells. Moreover, the HFHFD-induced decrease in Pparg expression appeared critical in the decrease of Treg cells at the level of the VAT and the inability to replenish the amount of Treg cells by the ACT, while the mechanism of Treg cell accumulation at the level of the SAT remained unclear.

In-Depth Study of Transmembrane Mucins in Association with Intestinal Barrier Dysfunction During the Course of T Cell Transfer and DSS-Induced Colitis

BACKGROUND AND AIMS

There is evidence for a disturbed intestinal barrier function in inflammatory bowel diseases [IBD] but the underlying mechanisms are unclear. Because mucins represent the major components of the mucus barrier and disturbed mucin expression is reported in the colon of IBD patients, we studied the association between mucin expression, inflammation and intestinal permeability in experimental colitis.

METHODS

We quantified 4-kDa FITC-dextran intestinal permeability and the expression of cytokines, mucins, junctional and polarity proteins at dedicated time points in the adoptive T cell transfer and dextran sodium sulfate [DSS]-induced colitis models. Mucin expression was also validated in biopsies from IBD patients.

RESULTS

In both animal models, the course of colitis was associated with increased interleukin-1β [IL-1β] and tumour necrosis factor-α [TNF-α] expression and increased Muc1 and Muc13 expression. In the T cell transfer model, a gradually increasing Muc1 expression coincided with gradually increasing 4-kDa FITC-dextran intestinal permeability and correlated with enhanced IL-1β expression. In the DSS model, Muc13 expression coincided with rapidly increased 4-kDa FITC-dextran intestinal permeability and correlated with TNF-α and Muc1 overexpression. Moreover, a significant association was observed between Muc1, Cldn1, Ocln, Par3 and aPKCζ expression in the T cell transfer model and between Muc13, Cldn1, Jam2, Tjp2, aPkcζ, Crb3 and Scrib expression in the DSS model. Additionally, MUC1 and MUC13 expression was upregulated in inflamed mucosa of IBD patients.

CONCLUSIONS

Aberrantly expressed MUC1 and MUC13 might be involved in intestinal barrier dysfunction upon inflammation by affecting junctional and cell polarity proteins, indicating their potential as therapeutic targets in IBD.

A Literature Review of the Potential Diagnostic Biomarkers of Head and Neck Neoplasms

Head and neck neoplasms have a poor prognosis because of their late diagnosis. Finding a biomarker to detect these tumors in an early phase could improve the prognosis and survival rate. This literature review provides an overview of biomarkers, covering the different -omics fields to diagnose head and neck neoplasms in the early phase. To date, not a single biomarker, nor a panel of biomarkers for the detection of head and neck tumors has been detected with clinical applicability. Limitations for the clinical implementation of the investigated biomarkers are mainly the heterogeneity of the study groups (e.g., small population in which the biomarker was tested, and/or only including high-risk populations) and a low sensitivity and/or specificity of the biomarkers under study. Further research on biomarkers to diagnose head and neck neoplasms in an early stage, is therefore needed.

Diet Reversal and Immune Modulation Show Key Role for Liver and Adipose Tissue T Cells in Murine Nonalcoholic Steatohepatitis

BACKGROUND & AIMS

Nonalcoholic steatohepatitis (NASH) is a multisystem condition, implicating liver and adipose tissue. Although the general involvement of the innate and adaptive immune system has been established, we aimed to define the exact role of the functionally diverse T-cell subsets in NASH pathogenesis through diet reversal and immunologic modulation.

METHODS

Multiple experimental set-ups were used in 8-week-old C57BL/6J mice, including prolonged high-fat high-fructose diet (HFHFD) feeding, diet reversal from HFHFD to control diet, and administration of anti-CD8a and anti-interleukin 17A antibodies. Plasma alanine aminotransferase, glucose, and lipid levels were determined. Liver and adipose tissue were assessed histologically. Cytotoxic T (Tc), regulatory T, T helper (Th) 1, and Th17 cells were characterized in liver and visceral adipose tissue (VAT) via flow cytometry and RNA analysis.

RESULTS

HFHFD feeding induced the metabolic syndrome and NASH, which coincided with an increase in hepatic Th17, VAT Tc, and VAT Th17 cells, and a decrease in VAT regulatory T cells. Although diet reversal induced a phenotypical metabolic and hepatic normalization, the observed T-cell disruptions persisted. Treatment with anti-CD8a antibodies decreased Tc cell numbers in all investigated tissues and induced a biochemical and histologic attenuation of the HFHFD-induced NASH. Conversely, anti-interleukin 17A antibodies decreased hepatic inflammation without affecting other features of NASH or the metabolic syndrome.

CONCLUSIONS

HFHFD feeding induces important immune disruptions in multiple hepatic and VAT T-cell subsets, refractory to diet reversal. In particular, VAT Tc cells are critically involved in NASH pathogenesis, linking adipose tissue inflammation to liver disease.

Volatomics in inflammatory bowel disease and irritable bowel syndrome

Volatile organic compounds (VOCs) are produced by the human metabolism, inflammation and gut microbiota and form the basis of innovative volatomics research. VOCs detected through breath and faecal analysis hence serve as attractive, non-invasive biomarkers for diagnosing and monitoring irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). This review describes the clinical applicability of volatomics in discriminating between IBS, IBD and healthy volunteers with acceptable accuracy in breath (70%-100%) and faecal (58%-85%) samples. Promising compounds are propan-1-ol for diagnosing and monitoring of IBD patients, and 1-methyl-4-propan-2-ylcyclohexa-1,4-diene as biomarker for IBS diagnosis. However, these VOCs often seem to be related to inflammation and probably will need to be used in conjunction with other clinical evidence. Furthermore, three interventional studies underlined the potential of VOCs in predicting treatment outcome and patient follow-up. This shows great promise for future use of VOCs as non-invasive breath and faecal biomarkers in personalised medicine. However, properly designed studies that correlate VOCs to IBD/IBS pathogenesis, while taking microbial influences into account, are still key before clinical implementation can be expected.

Effects of intestinal alkaline phosphatase on intestinal barrier function in a cecal ligation and puncture (CLP)-induced mouse model for sepsis

BACKGROUND

Sepsis is a severe pathological condition associated with systemic inflammation, intestinal inflammation, and gastrointestinal barrier dysfunction. Intestinal alkaline phosphatase (IAP) has been demonstrated to detoxify lipopolysaccharide, an important mediator in the pathophysiology of sepsis. We investigated the effect of treatment with IAP on intestinal permeability, intestinal inflammation, and bacterial translocation.

METHODS

OF-1 mice were divided into 4 groups (n = 12/group), undergoing either a sham or cecal ligation and puncture (CLP) procedure to induce sepsis. Mice received IAP or a vehicle intraperitoneally 5 minutes prior to the onset of the CLP or sham procedure, which was repeated every 12 hours for two consecutive days. After two days, in vivo intestinal permeability, intestinal inflammation, and bacterial translocation were determined.

KEY RESULTS

CLP-induced sepsis resulted in significantly more weight loss, worse clinical disease scores, bacterial translocation, and elevated inflammatory cytokines. Intestinal permeability was increased up to 5-fold (P < .001). IAP activity was significantly increased in septic animals. Treatment with IAP had no effect on clinical outcomes but reduced the increased permeability of the small intestine by 50% (P = .005). This reduction in permeability was accompanied by a modified gene expression of claudin-1 (P = .025), claudin-14 (P = .035), and interleukin 12 (P = .015). A discriminant analysis showed that treatment with IAP is linked to modified mRNA levels of several tight junction proteins and cytokines.

CONCLUSIONS AND INFERENCES

Treatment with IAP diminished CLP-induced intestinal barrier disruption, associated with modified expression of several cytokines and claudins. Nevertheless, this effect did not translate into better clinical outcomes in our experimental setup.

Mas-related G protein-coupled receptor C11 (Mrgprc11) induces visceral hypersensitivity in the mouse colon: A novel target in gut nociception?

BACKGROUND

Visceral hypersensitivity, an important cause of abdominal pain in disorders such as IBD and IBS, presents with a poorly understood pathophysiology and limited treatment options. Several members of the Mas-related G protein-coupled receptor family (Mrgprs) have become promising targets in pain research. The potential link between the murine Mrgpr C11 (Mrgprc11) and gut nociception is currently uninvestigated. Therefore, we explored the expression and functional role of Mrgprc11 in the gut nociceptive innervation.

METHODS

Mrgprc11 expression was evaluated in DRG neurons innervating the mouse colon using in situ hybridization and immunohistochemistry. Visceromotor responses to colorectal distension (CRD) assessed the effect of the Mrgprc11 agonist, BAM(8-22), on colonic pain sensitivity in healthy mice. Moreover, we determined pERK1/2-immunoreactivity in the thoracolumbar spinal cord after noxious CRD. Finally, from a translational point of view, we looked for expression of the human counterpart of Mrgprc11, MRGPRX1, in human thoracolumbar DRGs.

KEY RESULTS

In situ hybridization and immunohistochemistry revealed Mrgprc11 expression in colonic DRG neurons. Intracolonic administration of BAM(8-22) significantly increased colonic pain sensitivity in an Mrgprc11-dependent manner, and led to a significantly increased degree of neuronal activation in the splanchnic spinal cord upon noxious stimulation. Furthermore, MRGPRX1 expression was also detected in human thoracolumbar DRG neurons. CONCLUSIONS & INFERENCES: Our findings established a novel function for Mrgprc11 in the gut nociceptive innervation and propose the receptor as a new player in visceral hypersensitivity. Given the presence of MRGPRX1 in human DRG neurons, our study warrants future research on its therapeutic potential in abdominal pain disorders.

Clinical- and surgery-specific risk factors for post-operative sepsis: a systematic review and meta-analysis of over 30 million patients

Post-operative sepsis is a severe complication of surgery, which often worsens the clinical outcomes. While several risk factors have been identified, the importance of others remains uncertain. This systematic review and meta-analysis aimed to determine patient and surgery-related risk factors for post-operative sepsis. We reviewed Medline, the Web of Science, and the Cochrane library, systematically, for articles describing risk factors for sepsis. The role of eligible risk factors was investigated using a random-effects model, while analyzing univariate and multivariate data separately. Among 193 pro- and retrospective articles, comprising over 30 million patients, 38 eligible risk factors were selected for this meta-analysis. The patient-related risk factors associated with post-operative sepsis included male gender (odds ratio, OR 1.41), pre-existing heart failure (OR 2.53), diabetes (OR 1.41), and chronic kidney disease (OR 1.26). The surgery-related risk factors identified included emergency surgery (OR 3.38), peri-operative blood transfusion (OR 1.90), inpatient hospital stay (OR 2.31), and open surgery (OR 1.80). The adjusted overall incidence of surgical sepsis was 1.84%. In conclusion, multiple-patient and surgery-related risk factors are associated with the development of post-operative sepsis. Recognizing these risk factors could assist in the pre-operative identification of patients at risk of post-operative sepsis.

The Differential Roles of T Cells in Non-alcoholic Fatty Liver Disease and Obesity

Non-alcoholic fatty liver disease (NAFLD) constitutes a spectrum of disease states characterized by hepatic steatosis and is closely associated to obesity and the metabolic syndrome. In non-alcoholic steatohepatitis (NASH), additionally, inflammatory changes and hepatocellular damage are present, representing a more severe condition, for which the treatment is an unmet medical need. Pathophysiologically, the immune system is one of the main drivers of NAFLD progression and other obesity-related comorbidities, and both the innate and adaptive immune system are involved. T cells form the cellular component of the adaptive immune system and consist of multiple differentially active subsets, i.e., T helper (Th) cells, regulatory T (Treg) cells, and cytotoxic T (Tc) cells, as well as several innate T-cell subsets. This review focuses on the role of these T-cell subsets in the pathogenesis of NAFLD, as well as the association with obesity and type 2 diabetes mellitus, reviewing the available evidence from both animal and human studies. Briefly, Th1, Th2, Th17, and Th22 cells seem to have an attenuating effect on adiposity. Th2, Th22, and Treg cells seem to decrease insulin resistance, whereas Th1, Th17, and Tc cells have an aggravating effect. Concerning NAFLD, both Th22 and Treg cells appear to have an overall tempering effect, whereas Th17 and Tc cells seem to induce more liver damage and fibrosis progression. The evidence regarding the role of the innate T-cell subsets is more controversial and warrants further exploration.

Plasma donor-derived cell-free DNA kinetics after kidney transplantation using a single tube multiplex PCR assay

BACKGROUND

After transplantation, cell-free DNA derived from the donor organ (ddcfDNA) can be detected in the recipient's circulation. We aimed to quantify ddcfDNA levels in plasma of kidney transplant recipients thereby investigating the kinetics of this biomarker after transplantation and determining biological variables that influence ddcfDNA kinetics in stable and non-stable patients.

MATERIALS AND METHODS

From 107 kidney transplant recipients, plasma samples were collected longitudinally after transplantation (day 1-3 months) within a multicenter set-up. Cell-free DNA from the donor was quantified in plasma as a fraction of the total cell-free DNA by next generation sequencing using a targeted, multiplex PCR-based method for the analysis of single nucleotide polymorphisms. A subgroup of stable renal transplant recipients was identified to determine a ddcfDNA threshold value.

RESULTS

In stable transplant recipients, plasma ddcfDNA% decreased to a mean (SD) ddcfDNA% of 0.46% (± 0.21%) which was reached 9.85 (± 5.6) days after transplantation. A ddcfDNA threshold value of 0.88% (mean + 2SD) was determined in kidney transplant recipients. Recipients that did not reach this threshold ddcfDNA value within 10 days after transplantation showed a higher ddcfDNA% on the first day after transplantation and demonstrated a higher individual baseline ddcfDNA%.

CONCLUSION

In conclusion, plasma ddcfDNA fractions decreased exponentially within 10 days after transplantation to a ddcfDNA threshold value of 0.88% or less. To investigate the role of ddcfDNA for rejection monitoring of the graft, future research is needed to determine causes of ddcfDNA% increases above this threshold value.

Severe steatosis induces portal hypertension by systemic arterial hyporeactivity and hepatic vasoconstrictor hyperreactivity in rats

Non-alcoholic fatty liver disease (NAFLD) has become the most prevalent chronic liver disease. The presence of portal hypertension has been demonstrated in NAFLD prior to development of inflammation or fibrosis, and is a result of extrahepatic and intrahepatic factors, principally driven by vascular dysfunction. An increased intrahepatic vascular resistance potentially contributes to progression of NAFLD via intralobular hypoxia. However, the exact mechanisms underlying vascular dysfunction in NAFLD remain unknown. This study investigates systemic hemodynamics and both aortic and intrahepatic vascular reactivity in a rat model of severe steatosis. Wistar rats were fed a methionine-choline-deficient diet, inducing steatosis, or control diet for 4 weeks. In vivo hemodynamic measurements, aortic contractility studies, and in situ liver perfusion experiments were performed. The mean arterial blood pressure was lower and portal blood pressure was higher in steatosis compared to controls. The maximal contraction force in aortic rings from steatotic rats was markedly reduced compared to controls. While blockade of nitric oxide (NO) production did not reveal any differences, cyclooxygenase (COX) blockade reduced aortic reactivity in both controls and steatosis, whereas effects were more pronounced in controls. Effects could be attributed to COX-2 iso-enzyme activity. In in situ liver perfusion experiments, exogenous NO donation or endogenous NO stimulation reduced the transhepatic pressure gradient (THPG), whereas NO synthase blockade increased the THPG only in steatosis, but not in controls. Alpha-1-adrenergic stimulation and endothelin-1 induced a significantly more pronounced increase in THPG in steatosis compared to controls. Our results demonstrate that severe steatosis, without inflammation or fibrosis, induces portal hypertension and signs of a hyperdynamic circulation, accompanied by extrahepatic arterial hyporeactivity and intrahepatic vascular hyperreactivity. The arterial hyporeactivity seems to be NO-independent, but appears to be mediated by specific COX-2-related mechanisms. Besides, the increased intrahepatic vascular resistance in steatosis appears not to be NO-related but rather to vasoconstrictor hyperreactivity.

Newly developed serine protease inhibitors decrease visceral hypersensitivity in a post-inflammatory rat model for irritable bowel syndrome

BACKGROUND AND PURPOSE

Serine proteases have been re suggested as important mediators of visceral pain. We investigated their effect by using newly developed serine protease inhibitors with a well-characterized inhibitory profile in a rat model of post-inflammatory irritable bowel syndrome (IBS).

EXPERIMENTAL APPROACH

Colitis was induced in rats receiving intrarectal trinitrobenzenesulphonic acid; controls received 0.9% NaCl. Colonoscopies were performed on day 3, to confirm colitis, and later until mucosal healing. Visceral hypersensitivity was quantified by visceromotor responses (VMRs) to colorectal distension, 30 min after i.p. injection of the serine protease inhibitors nafamostat, UAMC-00050 or UAMC-01162. Serine proteases, protease-activated receptors (PARs) and TRP channels were quantified by qPCR and immunohistochemistry. Proteolytic activity was characterized using fluorogenic substrates.

KEY RESULTS

VMR was significantly elevated in post-colitis rats. Nafamostat normalized VMRs at the lowest dose tested. UAMC-00050 and UAMC-01162 significantly decreased VMR dose-dependently. Expression of mRNA for tryptase-αβ-1and PAR4, and tryptase immunoreactivity was significantly increased in the colon of post-colitis animals. Trypsin-like activity was also significantly increased in the colon but not in the faeces. PAR2 and TRPA1 immunoreactivity co-localized with CGRP-positive nerve fibres in control and post-colitis animals.

CONCLUSIONS AND IMPLICATIONS

Increased expression of serine proteases and activity together with increased expression of downstream molecules at the colonic and DRG level and in CGRP-positive sensory nerve fibres imply a role for serine proteases in post-inflammatory visceral hypersensitivity. Our results support further investigation of serine protease inhibitors as an interesting treatment strategy for IBS-related visceral pain.

Failed Downregulation of Circulating MicroRNA-155 in the Early Phase after ST Elevation Myocardial Infarction Is Associated with Adverse Left Ventricular Remodeling

BACKGROUND

MicroRNA are noncoding RNA that have a significant role in both inflammatory and cardiovascular diseases.

AIMS

We aimed to assess whether the inflammation-related microRNA-155 is associated with the development of adverse left ventricular (LV) remodeling following ST elevation myocardial infarction (STEMI).

METHODS

Peripheral blood samples were collected in the inflammatory (day 2), proliferative (day 5), and maturation phases (6 months) after STEMI (n = 20). Granulocytes, monocytes, and lymphocytes were enumerated with flow cytometry. The changes in LV volumes were assessed with 3-D echocardiography on day 1 and after 6 months. Adverse remodeling was defined as a >20% increase in end-diastolic volume. Healthy subjects were recruited as controls.

RESULTS

MicroRNA-155 measured on day 5 correlated positively with the relative change in end-diastolic volume (ρ = 0.490, p = 0.028). MicroRNA-155 (day 5) was significantly higher in patients with compared to patients without adverse LV remodeling. The expression level was similar in healthy subjects (n = 8) and in patients with LV remodeling. There was a positive correlation between microRNA-155 and the amount of monocytes (day 5, ρ = 0.463, p = 0.046).

CONCLUSION

Impaired downregulation of microRNA-155 during the second phase of the post- STEMI inflammatory response is a determinant of the development of adverse LV remodeling.

Regulation of intestinal permeability: The role of proteases

The gastrointestinal barrier is - with approximately 400 m² - the human body’s largest surface separating the external environment from the internal milieu. This barrier serves a dual function: permitting the absorption of nutrients, water and electrolytes on the one hand, while limiting host contact with noxious luminal antigens on the other hand. To maintain this selective barrier, junction protein complexes seal the intercellular space between adjacent epithelial cells and regulate the paracellular transport. Increased intestinal permeability is associated with and suggested as a player in the pathophysiology of various gastrointestinal and extra-intestinal diseases such as inflammatory bowel disease, celiac disease and type 1 diabetes. The gastrointestinal tract is exposed to high levels of endogenous and exogenous proteases, both in the lumen and in the mucosa. There is increasing evidence to suggest that a dysregulation of the protease/antiprotease balance in the gut contributes to epithelial damage and increased permeability. Excessive proteolysis leads to direct cleavage of intercellular junction proteins, or to opening of the junction proteins via activation of protease activated receptors. In addition, proteases regulate the activity and availability of cytokines and growth factors, which are also known modulators of intestinal permeability. This review aims at outlining the mechanisms by which proteases alter the intestinal permeability. More knowledge on the role of proteases in mucosal homeostasis and gastrointestinal barrier function will definitely contribute to the identification of new therapeutic targets for permeability-related diseases.

Long-Term Depletion of Conventional Dendritic Cells Cannot Be Maintained in an Atherosclerotic Zbtb46-DTR Mouse Model

BACKGROUND AND AIMS

Increased evidence suggests a pro-atherogenic role for conventional dendritic cells (cDC). However, due to the lack of an exclusive marker for cDC, their exact contribution to atherosclerosis remains elusive. Recently, a unique transcription factor was described for cDC, namely Zbtb46, enabling us to selectively target this cell type in mice.

METHODS

Low-density lipoprotein receptor-deficient (Ldlr-/-) mice were transplanted with bone marrow from Zbtb46-diphtheria toxin receptor (DTR) transgenic mice following total body irradiation. Zbtb46-DTR→Ldlr-/- chimeras were fed a Western-type diet for 18 weeks while cDC were depleted by administering diphtheria toxin (DT).

RESULTS

Although we confirmed efficient direct induction of cDC death in vitro and in vivo upon DT treatment of Zbtb46-DTR mice, advanced atherosclerotic plaque size and composition was not altered. Surprisingly, however, analysis of Zbtb46-DTR→Ldlr-/- chimeras showed that depletion of cDC was not sustained following 18 weeks of DT treatment. In contrast, high levels of anti-DT antibodies were detected.

CONCLUSIONS

Because of the observed generation of anti-DT antibodies and consequently the partial depletion of cDC, no clear decision can be taken on the role of cDC in atherosclerosis. Our results underline the unsuitability of Zbtb46-DTR→Ldlr-/- mice for studying the involvement of cDC in maintaining the disease process of atherosclerosis, as well as of other chronic inflammatory diseases.

Visceral hypersensitivity in inflammatory bowel diseases and irritable bowel syndrome: The role of proteases

Proteases, enzymes catalyzing the hydrolysis of peptide bonds, are present at high concentrations in the gastrointestinal tract. Besides their well-known role in the digestive process, they also function as signaling molecules through the activation of protease-activated receptors (PARs). Based on their chemical mechanism for catalysis, proteases can be classified into several classes: serine, cysteine, aspartic, metallo- and threonine proteases represent the mammalian protease families. In particular, the class of serine proteases will play a significant role in this review. In the last decades, proteases have been suggested to play a key role in the pathogenesis of visceral hypersensitivity, which is a major factor contributing to abdominal pain in patients with inflammatory bowel diseases and/or irritable bowel syndrome. So far, only a few preclinical animal studies have investigated the effect of protease inhibitors specifically on visceral sensitivity while their effect on inflammation is described in more detail. In our accompanying review we describe their effect on gastrointestinal permeability. On account of their promising results in the field of visceral hypersensitivity, further research is warranted. The aim of this review is to give an overview on the concept of visceral hypersensitivity as well as on the physiological and pathophysiological functions of proteases herein.

Sleep disordered breathing and autonomic function in overweight and obese children and adolescents

Obstructive sleep apnoea (OSA), common in children with obesity, is associated with cardiovascular morbidity. Autonomic dysfunction has been suggested to be a key player in the development of these complications. We investigated the relationship between obesity, OSA and sympathetic activity in children.

191 children with obesity were included and distributed into two groups: 131 controls and 60 with OSA. Beat-to-beat RR interval data were extracted from polysomnography for heart rate variability analysis. Urinary free cortisol levels were determined.

Urinary free cortisol did not differ between groups and was not associated with OSA, independent of the level of obesity. Differences in heart rate variability measures were found: mean RR interval decreased with OSA, while low/high-frequency band ratio and mean heart rate increased with OSA. Heart rate variability measures correlated with OSA, independent of obesity parameters and age: oxygen desaturation index correlated with mean heart rate (r=0.19, p=0.009) and mean RR interval (r= −0.18, p=0.02), while high-frequency bands and low/high-frequency band ratio correlated with arterial oxygen saturation measured by pulse oximetry (S_pO2) (r= −0.20, p=0.008 and r= −0.16, p=0.04) and S_pO2 nadir (r=0.23, p=0.003 and r= −0.19, p=0.02).

These results suggest that sympathetic heart activity is increased in children with obesity and OSA. Measures of hypoxia were related to increased sympathetic tone, suggesting that intermittent hypoxia is involved in autonomic dysfunction.

Sympathetic heart activity is increased in children with obstructive sleep apnoea and obesityhttp://ow.ly/iSVc305AZRv