Intestinal Permeability is Increased in Children Born Preterm, with Persistent Growth Delay and Intrauterine Growth Restriction

Background and Aim: Recent studies have shown that prematurity might generate abnormalities of intestinal permeability (IP). Our pilot study has assessed IP in a cohort of preterm children with history of intrauterine growth restriction (IUGR) and persistent growth delay. Patients and Methods: We reviewed clinical charts of preterm infants born between December 2010 and January 2015, selecting children above 4 years of age, born preterm (<36 weeks), small for gestational age (SGA), with a documented history of IUGR and persistent stunted growth. Ten children (6 males, age range: 4-8 years), and 10 healthy controls (6 males, age range: 6.5-10 years) were assessed. All patients performed lactulose/mannitol (L/M) ratio test to evaluate IP. Results: IP was significantly increased in patients compared to controls (0.0945 ±0.063 versus 0.0158±0.006, respectively, p <0,05), being pathologically high (>0.003) in 100% of patients compared to 5% of healthy subjects. Conclusions: IP is increased in preterm children with history of IUGR and growth delay at pre-schooler age, suggesting a role in their persistently poor growth. Further studies on larger series of children are needed to clarify the contribution of IP in the pathogenesis of restricted growth patterns.


Introduction
Intrauterine growth restriction (IUGR) is a clinical condition in which foetus cannot develop its own growth potential [1,2]. One of the mechanisms leading to IUGR is placental insufficiency [3], well studied in utero by doppler Fluximetry [4]. Because of hypoxia, for the assessment of IP and eventually malabsorption [6]. The aim of this study was to evaluate IP in preterm children with history of IUGR and persistent growth delay at pre-schooler age, following the hypothesis that an increased IP may stay behind a chronic malabsorption and growth retardation.

Patients and Methods
We

Lactulose/Mannitol Ratio
All children underwent IP study by measuring the urinary L/M Ratio [8,9]. For the 48 hours before and during the test, all patients followed an elimination diet. Before starting the test, a pre-test urine sample was collected, added with 1ml of chlorhexidine and stored at -20°C. Subsequently a drinking solution, made of 1g of Mannitol and 5g of Lactulose melted in about 100ml of water, was administered. One hour after, the patients began collecting urine for the next 6 hours in a 24-hour container added with 1ml of chlorhexidine. At the end of the test, a 10ml aliquot of this urine was frozen at -20°C and subsequently analysed. The patient's L/M ratios were then compared with those obtained in the control group.

Statistical Analysis
Study data were entered into Excel spreadsheets (Microsoft, Redmond, WA, USA) and analysed with GraphPad PRISM software (version 5.1; GraphPad Software. Inc., San Diego CA, USA).
Descriptive analysis was expressed as mean ± standard deviation (SD) and percentages. Ordinal variables were evaluated using the nonparametric Mann Whitney test. A p value < 0.05 was considered statistically significant.

Results
Epidemiological features and growth parameters of study population are summarized in Table 1. Mean GE of cases was 29,2 weeks (±4,5), at birth mean weight was 702,5 gr (±240,2) and mean length 32,4cm (±2, 8). As expected, weight and length at birth were significantly different between cases and controls. This data kept being significantly different also a time of last evaluation (Table   1). IP values measured by L/M ratio were significantly higher in patients than in controls (L/M cases 0.0945 ± 0.063; L/M controls: 0.158 ± 0.06; p <0.001) ( Table 1). All patients showed a pathological L/M ratio -i.e., higher than 0.03.  IP can lead to malabsorption; moreover, it augments the exposure of the entero-hepatic circulation to gut-derived bacterial products, such as lipopolysaccharides (LPS), determining a chronic lowgrade endotoxemia [6]. Following the hypothesis that BFC is linked to increased IP and malabsorption, we aimed to assess whether IP is increased in ex-premature children with history of IUGR and persistent growth delay.
The main finding of our study is the persistent increase of IP in paediatric patients born prematurely, with a documented history of IUGR and a persistent height and weight growth delay.
This is the first study that highlights this data since others [10][11][12] have observed an altered IP in animal models and in infants born prematurely within the 3 rd month of life. These findings may show that underlying the persistent growth restriction, there is a permanent state of "leaky gut" due to a TJ disruption process, finally leading to malabsorption. To modulate IP with a conscious use of pre and probiotics, may be an interesting perspective in this field. Gut microbiota may represent a new therapeutic target in paediatric growth restriction, when sustained by increased IP and malabsorption. Our study has some limitations. The main limitation is the small sample size and the retrospective recruitment of study population. The second one is the absence of a control group of children with a personal history of IUGR and preterm birth, but with regular growth. In conclusion, our study demonstrated a possible role of increased IP in growth delay of children born preterm with IUGR and growth delay. In the assessment of Pediatric growth delay leaky gut should be considered in the multidisciplinary evaluation to personalize treatment options.