Risk for Nonalcoholic Fatty Liver Disease in Young Adults Born Preterm

Determinants of non-alcoholic fatty liver disease in young people: Maternal, neonatal, and adolescent factors

AIM

To assess the impact of maternal, neonatal, and adolescent factors on the development of non-alcoholic fatty liver disease (NAFLD) in a cohort of 14- to 19-year-old adolescents.

METHODS

This study is part of the Early Vascular Ageing in the YOUth study, a single-center cross-sectional study conducted in western Austria. Maternal and neonatal factors were extracted from the mother-child booklet, adolescent factors were evaluated by a face-to-face interview, physical examination, and fasting blood analyses. Liver fat content was assessed by controlled attenuation parameter (CAP) using signals acquired by FibroScan® (Echosense, Paris, France). The association of maternal, neonatal, and adolescent factors with CAP values was analyzed using linear regression models.

RESULTS

In total, 595 adolescents (27.2% male) aged 17.0 ± 1.3 years were included. 4.9% (n = 29) showed manifest NAFLD with CAP values above the 90th percentile. Male sex (p < 0.001), adolescent triglyceride levels (p = 0.021), Homeostatic Model Assessment for Insulin Resistance index and BMI z-score (p < 0.001, each) showed a significant association with liver fat content in the multivariable analysis. Maternal pre-pregnancy BMI was associated with CAP values after adjustment for sex, age, and birth weight for gestational age (p < 0.001), but this association was predominantly mediated by adolescent BMI (indirect effect b = 1.18, 95% CI [0.69, 1.77]).

CONCLUSION

Components of the metabolic syndrome were the most important predictors of adolescent liver fat content. Therefore, prevention of NAFLD should focus on lifestyle modification in childhood and adolescence.

Disturbances of the Lung Glutathione System in Adult Guinea Pigs Following Neonatal Vitamin C or Cysteine Deficiency

In premature infants receiving parenteral nutrition, oxidative stress is a trigger for the development of bronchopulmonary dysplasia, which is an important factor in the development of adult lung diseases. Neonatal vitamin C and glutathione deficiency is suspected to induce permanent modification of redox metabolism favoring the development of neonatal and adult lung diseases. A total of 64 3-day-old guinea pigs were fed an oral diet that was either complete or deficient in vitamin C (VCD), cysteine (CD) (glutathione-limiting substrate) or both (DD) for 4 days. At 1 week of age, half of the animals were sacrificed while the other started a complete diet until 12 weeks of age. At 1 week, the decrease in lung GSH in all deficient groups was partially explained by the oxidation of liver methionine-adenosyltransferase. mRNA levels of kelch-like ECH-associated protein 1 (Keap1), glutathione-reductase (Gsr) and glutaredoxin-1 (Glrx) were significantly lower only in CD but not in DD. At 12 weeks, glutathione levels were increased in VCD and CD. Keap1, Gsr and Glrx mRNA were increased, while glutathione-reductase and glutaredoxin proteins were lower in CD, favoring a higher glutathionylation status. Both neonatal deficiencies result in a long-term change in glutathione metabolism that could contribute to lung diseases' development.

Factors early in life associated with hepatic steatosis

BACKGROUND

The rise in prevalence of non-alcoholic fatty liver disease (NAFLD) mirrors the obesity epidemic. NAFLD is insidious but may gradually progress from simple steatosis to steatohepatitis, fibrosis and cirrhosis and/or hepatocellular carcinoma. Intervention strategies to ameliorate developmental programming of NAFLD may be more efficacious during critical windows of developmental plasticity.

AIM

To review the early developmental factors associated with NAFLD.

METHODS

Databases MEDLINE via PubMed, and EMBASE and Reference Citation Analysis were searched and relevant publications up to April 30, 2021 were assessed. Original research studies that included risk factors associated with early development of NAFLD in human subjects were included. These factors include: Maternal factors, intrauterine and prenatal factors, post-natal factors, genetic and ethnic predisposition, childhood and adolescence environmental factors. Studies were excluded if they were review articles or animal studies, case reports or conference abstracts, or if NAFLD was not clearly defined and assessed radiologically.

RESULTS

Of 1530 citations identified by electronic search, 420 duplicates were removed. Of the 1110 citations screened from title and abstract, 80 articles were included in the final analysis. Genetic polymorphisms such as patatin-like phospholipase domain-containing protein 3 (PNPLA3) and membrane-bound O-acyltransferase domain-containing protein 7 (MBOAT7) were associated with increased risk of NAFLD. Familial factors such as maternal obesogenic environment and parental history of hepatic steatosis was associated with offspring NAFLD. Longer duration of exclusive breastfeeding in infancy was associated with a lower risk of developing NAFLD later in life while metabolic dysfunction and/or obesity in adolescence was associated with increased risk of NAFLD. Studies relating to socioeconomic factors and its association with NAFLD reported confounding results.

CONCLUSION

Maternal metabolic dysfunction during pregnancy, being exclusively breastfed for a longer time postnatally, diet and physical activity in childhood and adolescence are potential areas of intervention to decrease risk of NAFLD.

Maternal and Perinatal Risk Factors for Pediatric Nonalcoholic Fatty Liver Disease: A Systematic Review

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) has become the most common pediatric liver disease. The intrauterine and early life environment can have an important impact on long-term metabolic health. We investigated the impact of maternal prepregnancy obesity, (pre)gestational diabetes, breastfeeding, and birth anthropometrics/preterm birth on the development of NAFLD in children and adolescents.

METHODS

A comprehensive search was performed in MEDLINE, PubMed Central, EMBASE, and grey literature databases through August 2020. The primary outcome was the prevalence of pediatric NAFLD, whereas the histologic severity of steatohepatitis and/or fibrosis were secondary outcomes. Study selection, data extraction, and quality assessment were performed by 2 independent reviewers.

RESULTS

Our systematic review included 33 articles. Study heterogeneity regarding patient populations, diagnostic tools, and overall quality was considerable. Eight studies determined the impact of maternal prepregnancy overweight/obesity and identified this as a possible modifiable risk factor for pediatric NAFLD. Conversely, 8 studies investigated (pre)gestational diabetes, yet the evidence on its impact is conflicting. Breastfeeding was associated with a reduced risk for NAFLD, steatohepatitis, and fibrosis, especially in studies that evaluated longer periods of breastfeeding. Being born preterm or small for gestational age has an unclear impact on the development of NAFLD, although an early catch-up growth might drive NAFLD.

CONCLUSIONS

In a systematic review, we found that maternal prepregnancy overweight and obesity were associated with an increased risk of pediatric NAFLD. Breastfeeding might be protective against the development of NAFLD when the duration of breastfeeding is sufficiently long (≥6 months).

Neonatal Vitamin C and Cysteine Deficiencies Program Adult Hepatic Glutathione and Specific Activities of Glucokinase, Phosphofructokinase, and Acetyl-CoA Carboxylase in Guinea Pigs' Livers

Premature neonates are submitted to an early-life oxidative stress from parenteral nutrition, which is vitamin C (VC) deficient and induces low endogenous levels of glutathione. The oxidative stress caused by these deficiencies may permanently affect liver glycolysis and lipogenesis. This study evaluates the short- and long-term effects of neonatal VC and cysteine deficient diets on redox and energy metabolism. Three-day-old Hartley guinea pigs from both sexes were given a regular or a deficient diet (VC, cysteine, or both) until week 1 of life. Half of the animals were sacrificed at this age, while the other half ate a complete diet until 12 weeks. Liver glutathione and the activity and protein levels of glucokinase, phosphofructokinase, and acetyl-CoA-carboxylase were measured. Statistics: factorial ANOVA (5% threshold). At 1 week, all deficient diets decreased glutathione and the protein levels of glucokinase and phosphofructokinase, while cysteine deficiency decreased acetyl-CoA-carboxylase levels. A similar enzyme level was observed in control animals at 12 weeks. At this age, VC deficiency decreased glutathione, while cysteine increased it. Acetyl-CoA-carboxylase protein levels were increased, which decreased its specific activity. Early-life VC and cysteine deficiencies induce neonatal oxidative stress and an adult-like metabolism, while predisposing to increased lipogenic rates during adulthood.

Association of age of initiation and type of complementary foods with body mass index and weight-for-length at 12 months of age in preterm infants

OBJECTIVE

To assess whether in very preterm infants (1) body mass index (BMI) Z-score and weight-for-length (WtFL) Z-score at 1 year of age and (2) head growth from discharge to 1 year are associated with breastfeeding at discharge and the age of onset and type of complementary foods.

STUDY DESIGN

Observational cohort study.

RESULTS

Infants started on only ready-made complementary (RMC) feedings at ≤26 weeks adjusted age had the highest adjusted BMI Z-score and WtFL Z-score at 1 year of age. Adjusted change in fronto-occipital circumference was highest in infants either discharged on breastmilk or receiving home-made complementary food with/without RMC (HMM) at ≤26 weeks adjusted age.

CONCLUSIONS

Infants started on RMC ≤26 weeks adjusted age had the highest BMI Z-score and WtFL Z-score at 1 year. Head growth from discharge to 1 year was highest in infants either discharged on breastmilk or receiving HMM at ≤26 weeks adjusted age.

Preterm Birth as a Risk Factor for Metabolic Syndrome and Cardiovascular Disease in Adult Life: A Systematic Review and Meta-Analysis

OBJECTIVE

To determine if preterm birth is associated with components of the metabolic syndrome in adult life.

STUDY DESIGN

A structured literature search was performed using PubMed. All comparative studies reported metabolic and cardiovascular outcomes in adults (≥18 years of age) born preterm (<37 weeks of gestation) compared with adults born at term (37-42 weeks of gestation) and published through March 2018 were included. The major outcomes assessed were body mass index, waist circumference, waist-to-hip ratio, fat mass, systolic blood pressure (SBP), diastolic blood pressure (DBP), 24-hour SBP, 24-hour DBP, endothelium-dependent brachial artery flow-mediated dilation, carotid intima-media thickness, pulse wave velocity, fasting glucose and insulin, Homeostasis Model Assessment-Estimated Insulin Resistance Index, and lipid profiles. Quality appraisal was performed using a modified version of the Newcastle-Ottawa scale. A meta-analysis was performed for comparable studies which reported sufficient data.

RESULTS

Forty-three studies were included, including a combined total of 18 295 preterm and 294 063 term-born adults. Prematurity was associated with significantly higher fat mass (P = .03), SBP (P < .0001), DBP (P < .0001), 24-hour SBP (P < .001), and 24-hour DBP (P < .001). Furthermore, preterm-born adults presented higher values of fasting glucose (P = .01), insulin (P = .002), Homeostasis Model Assessment-Estimated Insulin Resistance Index (P = .05), and total cholesterol levels (P = .05) in comparison with adults born at term, in random effect models. No statistically significant difference was found between preterm and term-born adults for the other outcomes studied.

CONCLUSIONS

Preterm birth is strongly associated with a number of components of the metabolic syndrome and cardiovascular disease in adult life.

Free-breathing 3-D quantification of infant body composition and hepatic fat using a stack-of-radial magnetic resonance imaging technique

BACKGROUND

Body composition and hepatic fat correlate with future risk for metabolic syndrome. In children, many conventional techniques for quantifying body composition and hepatic fat have limitations. MRI is a noninvasive research tool to study body composition and hepatic fat in infants; however, conventional Cartesian MRI is sensitive to motion, particularly in the abdomen because of respiration. Therefore we developed a free-breathing MRI technique to quantify body composition and hepatic fat in infants.

OBJECTIVE

In infants, we aimed to (1) compare the image quality between free-breathing 3-D stack-of-radial MRI (free-breathing radial) and 3-D Cartesian MRI in the liver and (2) determine the feasibility of using free-breathing radial MRI to quantify body composition and hepatic proton-density fat fraction (PDFF).

MATERIALS AND METHODS

Ten infants ages 2-7 months were scanned with free-breathing radial (two abdominal; one head and chest) and Cartesian (one abdominal) MRI sequences. The median preparation and scan times were reported. To assess feasibility for hepatic PDFF quantification, a radiologist masked to the MRI technique scored abdominal scans for motion artifacts in the liver using a 3-point scale (1, or non-diagnostic, to 3, or no artifacts). Median visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and brown adipose tissue (BAT) volume and PDFF, and hepatic PDFF were measured using free-breathing radial MRI. We assessed repeatability of free-breathing radial hepatic PDFF (coefficient of repeatability) between back-to-back scans. We determined differences in the distribution of image-quality scores using McNemar-Bowker tests. P<0.05 was considered significant.

RESULTS

Nine infants completed the entire study (90% completion). For ten infants, the median preparation time was 32 min and scan time was 24 min. Free-breathing radial MRI demonstrated significantly higher image-quality scores compared to Cartesian MRI in the liver (radial scan 1 median = 2 and radial scan 2 median = 3 vs. Cartesian median = 1; P=0.01). Median measurements using free-breathing radial were VAT=52.0 cm³, VAT-PDFF=42.2%, SAT=267.7 cm³, SAT-PDFF=87.1%, BAT=1.4 cm³, BAT-PDFF=26.1% and hepatic PDFF=3.4% (coefficient of repeatability <2.0%).

CONCLUSION

In this study, free-breathing radial MRI in infants achieved significantly improved liver image quality compared to Cartesian MRI. It is feasible to use free-breathing radial MRI to quantify body composition and hepatic fat in infants.

Exacerbation of liver steatosis following exposure to famine and overnutrition

SCOPE

People suffering from famine in early life and overnutrition in adulthood may have an increased risk for liver steatosis. We aimed to investigate the effects and mechanisms of early nutrition restriction and overnutrition on de novo lipogenesis in the liver.

METHODS AND RESULTS

Three-wk-old male rats were food restricted for 4 wk and refed a high-fat or normal fat diet individually in metabolic cages for 9 wk. Weight-matched groups were also set up. Fatty acid synthetase expression was measured to estimate de novo lipogenesis in the liver. Parameters of glucose and lipid metabolism were measured with isotope assays. All four groups had comparable body weights. However, the famine high-fat diet group had the highest degree of liver steatosis, the greatest body fat ratio, and insulin resistance. Lipid accumulation, fatty acid synthetase expression, and gluconeogenesis in the liver were significantly higher in the famine and high-fat diet groups (p < 0.05). Moreover, these groups also had markedly lower muscle glucose uptake.

CONCLUSION

Under famine and high-fat refeeding stress, rats were extremely susceptible to developing hepatic steatosis. This is presumably a consequence of upregulation of de novo lipogenesis and enhanced glucose flux from muscle to de novo lipogenesis in the liver.

Adult Consequences of Extremely Preterm Birth: Cardiovascular and Metabolic Diseases Risk Factors, Mechanisms, and Prevention Avenues

Extremely preterm babies are exposed to various sources of injury during critical stages of development. The extremely preterm infant faces premature transition to ex utero physiology and undergoes adaptive mechanisms that may be deleterious in the long term because of permanent alterations in organ structure and function. Perinatal events can also directly cause structural injury. These disturbances induce morphologic and functional changes in their organ systems that might heighten their risks for later adult chronic diseases. This review examines the pathophysiology of programming of long-term health and diseases after preterm birth and associated perinatal risk factors.

Long-term metabolic risk among children born premature or small for gestational age

Accumulating evidence suggests that both the intrauterine environment and growth during early life can influence the development of chronic noncommunicable diseases, such as type 2 diabetes mellitus and cardiovascular disease, in adulthood. Here, we review the available human data supporting increased metabolic risk among children born premature or small for gestational age; the adrenal and pubertal modifications that contribute to this risk; metabolic changes that occur during adolescence and early adulthood; and approaches to potentially modify or decrease risk of metabolic disease. The risks associated with delivery at term or preterm are compared for each period of life. Knowledge of these associations is fundamental for the paediatric community to develop preventive strategies early during postnatal life.

Indicators of fetal growth and adult liver enzymes: the Bogalusa Heart Study and the Cardiovascular Risk in Young Finns Study

Despite the interest in the relationship of fetal exposures to adult cardiovascular disease, few studies have examined indicators of adult fatty liver disease as an outcome. Previous results are inconsistent, and indicate possible variation by sex. Adult liver enzymes [γ-glutamyl transferase (GGT), alanine transaminase (ALT) and aspartase transaminase (AST)] were measured in two cohort studies: the Bogalusa Heart Study (BHS; n=1803) and the Cardiovascular Risk in Young Finns (YF; n=3571) study, which also had ultrasound measures of liver fat (n=2546). Predictors of dichotomized (clinical cut-offs) and continuous (within the reference range) liver enzymes included low birthweight (4000 g), small-for-gestational-age (birthweight 90th percentile), and preterm birth. Multiple logistic and linear regression were conducted, adjusted for medical, behavioral and socioeconomic indicators. Interactions with sex were also examined. In BHS, birth measures were not strongly associated with clinically high levels of liver enzymes, and within the reference range measures of reduced growth were associated with increased AST in women. In the YF study, at least one marker of reduced growth was associated with higher GGT, higher ALT and higher AST (in women). Probable fatty liver on ultrasound was associated with low birthweight (2.41, 1.42-4.09) and preterm birth (2.84, 1.70-4.76). These results suggest a link between birth parameters and adult fatty liver, but encourage consideration of population variation in these relationships.

Prevalence of hepatic steatosis in apparently healthy medical students: a transient elastography study on the basis of a controlled attenuation parameter

OBJECTIVE

Despite the increasing burden of nonalcoholic fatty liver disease (NAFLD) in modern societies, the optimal screening method to detect hepatic steatosis in the general population remains to be established. Controlled attenuation parameter (CAP) measured with transient elastography (TE) has recently emerged as a reliable imaging tool for the screening and diagnosis of NAFLD. Here, we sought to investigate the prevalence of TE-defined hepatic steatosis in a sample of apparently healthy medical students. We also assessed the relationships between CAP and traditional NAFLD risk factors.

MATERIALS AND METHODS

A total of 112 Turkish medical students (48 women and 64 men, mean age 20.5±1.1 years) underwent TE. On the basis of previous studies, a cut-off value of 238 dB/m for CAP was used for the diagnosis of hepatic steatosis.

RESULTS

On the basis of the selected cut-off for CAP, we identified 26 students (23.2%) with TE-defined NAFLD. Univariate correlation analyses showed that CAP values were significantly associated with BMI (r=0.40, P<0.001), waist circumference (r=0.39, P<0.001), and hip circumference (r=0.34, P<0.001). In multivariable analysis, only BMI retained its independent association with CAP (β=0.36, t=3.4, P<0.001).

CONCLUSION

NAFLD is highly prevalent even in apparently healthy young individuals. CAP assessment with TE may be useful for an early, noninvasive identification of hepatic steatosis.