Possible role of tryptophan metabolism along the microbiota-gut-brain axis on cognitive & behavioral aspects in Phenylketonuria

Cognitive and psychiatric disorders are well documented across the lifetime of patients with inborn errors of metabolism (IEMs). Gut microbiota impacts behavior and cognitive functions through the gut-brain axis (GBA). According to recent research, a broad spectrum of GBA disorders may be influenced by a perturbed Tryptophan (Trp) metabolism and are associated with alterations in composition or function of the gut microbiota. Furthermore, early-life diets may influence children's neurodevelopment and cognitive deficits in adulthood. In Phenylketonuria (PKU), since the main therapeutic intervention is based on a life-long restrictive diet, important alterations of gut microbiota have been observed. Studies on PKU highlight the impact of alterations of gut microbiota on the central nervous system (CNS), also investigating the involvement of metabolic pathways, such as Trp and kynurenine (KYN) metabolisms, involved in numerous neurodegenerative disorders. An alteration of Trp metabolism with an imbalance of the KYN pathway towards the production of neurotoxic metabolites implicated in numerous neurodegenerative and inflammatory diseases has been observed in PKU patients supplemented with Phe-free amino acid medical foods (AA-MF). The present review investigates the possible link between gut microbiota and the brain in IEMs, focusing on Trp metabolism in PKU. Considering the evidence collected, cognitive and behavioral well-being should always be monitored in routine IEMs clinical management. Further studies are required to evaluate the possible impact of Trp metabolism, through gut microbiota, on cognitive and behavioral functions in IEMs, to identify innovative dietetic strategies and improve quality of life and mental health of these patients.

Quality of life aspects of a low protein diet using GMP in patients with phenylketonuria

Objective

To assess some quality of life (QOL) aspects of a low protein diet, using glycomacropeptide (GMP) as a protein substitute in patients with phenylketonuria (PKU).

Methods

This was a multicentre, prospective observational cohort, study. Metabolic control, nutritional parameters, and dietary adherence were assessed in patients with PKU before (T0), and six months after (T6) starting a low protein diet using GMP. Selected items from the PKU-QOL questionnaire were used to assess patients’ acceptance of their modified diet.

Results

18 patients from three Italian Centres, completed the study. With the exception of LDL-cholesterol and vitamin 25OH-D concentrations, there were no differences between T0 and T6 in metabolic or nutritional parameters. Data suggested that patients have a good acceptance of protein substitutes containing GMP, probably because of their improved palatability.

Conclusions

According to our patients’ responses to items related to dietary regimen, GMP based protein substitutes do not appear to significantly affect QOL.

Dysbiosis, Host Metabolism, and Non-communicable Diseases: Trialogue in the Inborn Errors of Metabolism

Inborn errors of metabolism (IEMs) represent a complex system model, in need of a shift of approach exploring the main factors mediating the regulation of the system, internal or external and overcoming the traditional concept of biochemical and genetic defects. In this context, among the established factors influencing the metabolic flux, i.e., diet, lifestyle, antibiotics, xenobiotics, infectious agents, also the individual gut microbiota should be considered. A healthy gut microbiota contributes in maintaining human health by providing unique metabolic functions to the human host. Many patients with IEMs are on special diets, the main treatment for these diseases. Hence, IEMs represent a good model to evaluate how specific dietary patterns, in terms of macronutrients composition and quality of nutrients, can be related to a characteristic microbiota associated with a specific clinical phenotype (“enterophenotype”). In the present review, we aim at reporting the possible links existing between dysbiosis, a condition reported in IEMs patients, and a pro-inflammatory status, through an altered “gut-liver” cross-talk network and a major oxidative stress, with a repercussion on the health status of the patient, increasing the risk of non-communicable diseases (NCDs). On this basis, more attention should be paid to the nutritional status assessment and the clinical and biochemical signs of possible onset of comorbidities, with the goal of improving the long-term wellbeing in IEMs. A balanced intestinal ecosystem has been shown to positively contribute to patient health and its perturbation may influence the clinical spectrum of individuals with IEMs. For this, reaching eubiosis through the improvement of the quality of dietary products and mixtures, the use of pre-, pro- and postbiotics, could represent both a preventive and therapeutic strategy in these complex diseases.

The impact of a nutritional intervention based on egg white for phosphorus control in hemodialyis patients

BACKGROUND AND AIMS

Here we describe a dietary intervention for hyperphosphatemia in dialysis patients based on the partial replacement of meat and fish, which are one of the main sources of alimentary phosphorous, with egg white, a virtually phosphorous-free protein source. This intervention aims to reduce phosphorous intake without causing protein wasting.

PATIENTS AND METHODS

As many as 23 hyperphosphatemic patients (15 male and 8 female, mean age 53.0 ± 10.0 years) on chronic standard 4 h, three times weekly, bicarbonate hemodialysis were enrolled in this open-label, randomized controlled trial. Patients in the intervention group were instructed to replace fish or meat with egg white in three meals a week for three months whereas diet was unchanged in the control group.

RESULTS

Serum phosphate concentrations were significantly lower in the intervention group than in controls after three (4.9 ± 1.0 vs 6.6 ± 0.8; p < 0.001) but not after one month of treatment. Phosphate concentrations decreased more from baseline in the intervention than in the control group both after one (-1,2 ± 1,1 vs 0,5 ± 1,1; p = 0.004) and after three (-1,7 ± 1,1 vs -0,6 ± 1,1; p < 0.001) months of follow-up. No change either in body weight or in body composition assessed with bioelectrical impedance analysis or in serum albumin concentration was observed in either group.

CONCLUSION

The partial replacement of meat and fish with egg white induces a significant decrease in serum phosphate without causing protein malnutrition and could represent a useful instrument to control serum phosphate levels in hemodialysis patients. CLINICALTRIALS.

GOV IDENTIFIER

NCT03236701.

Predictors of fat-free mass loss 1 year after laparoscopic sleeve gastrectomy

PURPOSE

Laparoscopic sleeve gastrectomy (LSG) is one of the most frequently performed bariatric surgery interventions because of its safety and efficacy. Nevertheless, concerns have been raised on its detrimental effect on patient nutritional state that can ultimately lead to the loss of fat-free mass (FFM). There is interest in identifying predictors for the early identification of patients at risk of this highly unwanted adverse because they could benefit of nutritional preventive interventions. Therefore, we investigated whether anthropometric parameters, body composition or resting energy expenditure (REE) measured before surgery could predict FFM loss 1 year after LSG.

METHODS

Study design was retrospective observational. We retrieved data on body weight, BMI, body composition and REE before and 1 year after LSG from the medical files of 36 patients operated on by LSG at our institutions. Simple regression, the Oldham's method and multilevel analysis were used to identify predictors of FFM loss.

RESULTS

Averaged percentage FFM loss 1 year after LSG was 17.0 ± 7.7% with significant differences between sexes (20.8 ± 6.6 in males and 12.2 ± 6.1% in females, p < 0.001). FFM loss was strongly predicted by pre-surgery FFM and this effect persisted also after correcting for the contribution of sex.

CONCLUSIONS

High FFM values before surgery predict a more severe FFM loss after LSG. This factor could also account for the higher FFM loss in men than in women. Our finding could help in the early identification of patient requiring a nutritional support after LSG.

Prevalence of gastric myoelectrical abnormalities in patients with nonulcer dyspepsia and H. pylori infection: resolution after H. pylori eradication

The aims of this study were to investigate the effects of H. pylori eradication on gastric myoelectrical activity and dyspeptic symptoms. Sixty-two subjects with H. pylori infection and no active peptic ulcer participated in this study, which involved three sessions. Anti-H. pylori therapy consisting of clarithromycin and omeprazole was given for two weeks. Gastric myoelectrical activity was measured using surface electrogastrography and dyspeptic symptoms were scored at each session. A [14C] urea breath test was performed at baseline and one month after treatment. In comparison with baseline, the percentage of normal slow waves was significantly increased and the mean total symptom score was significantly reduced one and three months after therapy (P < 0.05). Approximately 40% of patients with nonulcer dyspepsia' symptoms and H. pylori infection have abnormal gastric myoelectrical activity, which may be normalized following the eradication of H. pylori infection. The normalization of gastric myoelectrical activity may be one explanation for the significant symptom improvement in this subset of the dyspepsia population after H. pylori eradication.

Impact of Helicobacter pylori colonization on immunoreactive epidermal growth factor and transforming growth factor-alpha in gastric juice. Its potential pathogenetic implications

Epidermal growth factor (EGF), pivotal in mucosal protection, is partly degraded proteolytically at low pH in the gastric milieu; gastric acid secretion, on the other hand, remains influenced by H. pylori colonization. The aim of this study, therefore, was to evaluate the impact of low pH and H. pylori colonization status on immunoreactive EGF and the other member of EGF-family, immunoreactive transforming growth factor-alpha (TGF-alpha). Eighteen patients with nonulcer dyspepsia (NUD) colonized by H. pylori and 55 NUD patients without H. pylori colonization were investigated. Gastric juice samples were aspirated at the beginning of the endoscopy procedure and immediately placed on ice, and their pH was recorded. The measurement of immunoreactive EGF and TGF-alpha was performed using commercially available radioimmunoassays (RIAs) after adjustment of pH to neutral using an assay buffer. Statistical analysis was performed using sigma-Stat for Windows. The concentration of immunoreactive EGF in patients with NUD colonized by H. pylori was 80% lower (P < 0.02) than in those without H. pylori and in both groups immunoreactive EGF was significantly lower when the pH of gastric juice was below 4.0. The concentration of immunoreactive EGF in H. pylori(+) and H. pylori(-) patients was similar when the pH of aspirated gastric juice was above 4.0. However, with gastric juice pH < 4.0, the EGF concentration was 64% lower in H. pylori(+) patients than H. pylori(-) patients (P < 0.05). In general, the concentration of immunoreactive TGF-alpha in gastric juice was unaffected by H. pylori colonization or pH of gastric juice. It is concluded that: (1) significantly lower immunoreactive EGF concentrations in patients with pH below 4.0 indicate that immunoreactive EGF but not immunoreactive TGF-alpha is affected by an acidic gastric milieu; (2) the further reduction of gastric juice immunoreactive EGF at pH below 4.0 in patients colonized by H. pylori suggests that this microorganism may elaborate factors that accelerate its proteolytic degradation or inhibit its rate of synthesis and/or secretion; and (3) this diminished content of immunoreactive EGF at low pH, especially in patients colonized by H. pylori, may facilitate the development and/or progression of mucosal damage.

Prostaglandin E2 content in residual gastric juice reflects endoscopic damage to the gastric mucosa after naproxen sodium administration

OBJECTIVES

The diagnostic potential of residual gastric juice for development of naproxen sodium-induced mucosal damage has not been explored. We studied prostaglandin E2 (PGE2) content in residual gastric juice before and after naproxen sodium administration and assessed relationships with endoscopic mucosal damage.

METHODS

Thirty volunteers received the recommended over-the-counter dose (660 mg/day) of naproxen sodium or placebo in this 7-day, double-blind, endoscopically controlled, cross-over study.

RESULTS

PGE2 concentration in gastric juice did not increase after placebo; naproxen significantly reduced PGE2 concentration (p < 0.001). In three subjects in whom no endoscopic changes occurred after naproxen administration, PGE2 concentration increased by 14%. In seven subjects who developed hemorrhagic changes, PGE2 concentration declined by 50% (p = 0.08). In 20 subjects who developed numerous hemorrhagic and erosive changes within the antral mucosa, PGE2 concentration declined by 70% (p < 0.001). The starting PGE2 value in subjects with severe mucosal hemorrhagic and erosive changes after naproxen was almost eightfold higher than in subjects who did not develop mucosal damage (p = 0.007) and 67% higher than in subjects with hemorrhagic changes only (p = 0.25).

CONCLUSION

PGE2 measurement in residual gastric juice, aspirated before and after nonsteroidal antiinflammatory drug treatment, may be useful in monitoring mucosal damage and may identify patients who are likely to develop endoscopic mucosal changes.

Inhibitory effects of cholecystokinin on postprandial gastric myoelectrical activity

While a number of studies have investigated the effects of cholecystokinin (CCK) on gastrointestinal motility, little is known on the effects of CCK on gastric myoelectrical activity, which regulates gastric motility. The aim of this study was to investigate the effects of intravenous infusion of CCK-8 on gastric myoelectrical activity in normal humans. Gastric myoelectrical activity was measured in 10 healthy subjects with a noninvasive electrogastrographic technique by placing abdominal electrodes on the epigastric area. Two study sessions were performed in each subject on two separate days with double-blinded infusion of either saline or CCK (24 pmol/kg/hr). The procedure for each session was as follows: (A) 30-min baseline fasting electrogastrogram (EGG); (B) start infusion, another 30-min EGG; (C) give meal, 60-min EGG; and (D) stop infusion, another 60-min EGG. The dominant frequency and peak power (amplitude) of the EGG, and the percentage of normal 2-4 cycles/min slow waves during each recording session were computed and compared between placebo and CCK. It was found that normal 3 cpm slow waves were recorded in all EGGs. Infusion of CCK had no effect on the frequency of the gastric slow wave and did not induce gastric dysrhythmias. It was also found that intravenous infusion of CCK significantly decreased the EGG peak power (amplitude) during the first hour after the meal (the infusion was given during this period) in comparison with placebo (P < 0.05). This inhibitory effect on EGG peak power was sustained but not significant during the second postprandial hour (the infusion was not given during this period). It was concluded that intravenous infusion of CCK at a physiological concentration significantly decreased the postprandial EGG amplitude in normal humans, suggesting an inhibitory effect on postprandial gastric motility, but did not change the frequency and regularity of the gastric slow wave.