Impact of postnatal steroids on peripheral avascular retina and severity of retinopathy of prematurity.

BACKGROUND: We investigated the role of postnatal steroids on the severity of retinopathy of prematurity (ROP) and its impact on peripheral avascular retina (PAR). METHODS: A retrospective cohort study of infants born at ≤32 weeks gestation and/or birth weight ≤1500 g. Demographics, the dose and duration of steroid treatment, and age when full retinal vascularization occurred were collected. The primary outcomes were the severity of ROP and time to full vascularization of the retina. RESULTS: A total of 1695 patients were enrolled, 67% of whom received steroid therapy. Their birth weight was 1142 ± 396 g and gestational age was 28.6 ± 2.7 weeks. The total hydrocortisone-equivalent dose prescribed was 28.5 ± 74.3 mg/kg. The total days of steroid treatment were 8.9 ± 35.1 days. After correction for major demographic differences, infants who received a higher cumulative dose of steroids for a longer duration had a significantly increased incidence of severe ROP and PAR (P < 0.001). For each day of steroid treatment, there was a 3.2% increase in the hazard of the severe form of ROP (95% CI: 1.022-1.043) along with 5.7% delay in achieving full retinal vascularization (95% CI: 1.04-1.08) (P < 0.001). CONCLUSION: Cumulative dose and duration of postnatal steroid use were independently associated with the severity of ROP and PAR. Thus, postnatal steroids should be used very prudently. IMPACT: We report ROP outcomes in a large cohort of infants from two major healthcare systems where we have studied the impact of postnatal steroids on the severity of ROP, growth, and development of retinal vessels. After correcting our data for three major outcome measures, we show that high-dose postnatal steroids used for a prolonged duration of time are independently associated with severe ROP and delay in retinal vascularization. Postnatal steroids impact the visual outcomes of VLBW infants significantly, so their clinical use needs to be moderated.

Postnatal glucocorticoid use impacts renal function in VLBW neonates.

BACKGROUND: Preterm neonates often require glucocorticoids to manage refractory hypotension, prevent, and treat bronchopulmonary dysplasia. We have investigated the effect of cumulative dose and duration of glucocorticoids on blood pressure and renal function in VLBW infants. METHODS: In this retrospective cohort study, medical records of infants (GA ≤ 35 weeks) born January 2015 to December 2019 were reviewed to extract demographic and clinical characteristics, dose and duration of steroids, blood pressure (BP), and creatinine at the time of discharge from the neonatal intensive care unit. RESULTS: Two hundred and eighty-three neonates with average GA (28 ± 3 weeks) and birthweight (1060±381 g). Twenty-eight percent (33/116) of infants who received postnatal steroids developed hypertension versus 16% (27/167) of controls (OR = 2.0, p = 0.011). There was a correlation between the cumulative dosage of postnatal steroids and systolic BP (R2 = 0.06, p < 0.001). With increasing steroid dose and total steroid days, there was a significant increase in creatinine clearance at the time of discharge (R2 = 0.13, p < 0.001; R2 = 0.13, p < 0.001, respectively). CONCLUSIONS: Cumulative dose of postnatal steroids and duration of use is associated with increased systolic BP in premature infants. Postnatal steroids should be used prudently to prevent long-term cardiovascular and renal morbidity. IMPACT: Preterm neonates are exposed to a high dose of glucocorticoids during their neonatal intensive care stay. The dose and duration of use of postnatal glucocorticoids was associated with significant increase in blood pressure at the time of discharge in preterm neonates. Postnatal glucocorticoid use is associated with improved creatinine clearance likely due to a state of hyperfiltration and may lead to chronic kidney disease later in life. Postnatal glucocorticoids should be used prudently in this highly vulnerable population.

Risk of Iodine Deficiency in Extremely Low Gestational Age Newborns on Parenteral Nutrition.

Iodine is an essential component of thyroid hormones, which play a critical role in neurodevelopment. The iodine status of pregnant women and their newborns is not checked routinely. Extremely Low Gestational Age Newborns do not receive Iodine supplementation while on parenteral nutrition (PN). We measured urine iodine levels and thyroid function tests in 50 mother-infant dyads at birth, at 1 week, 1, 2, 3 months and near discharge. We correlated maternal and neonatal urine iodine levels with thyroid functions and measured iodine levels in milk and PN. In our study, 64% of mothers were iodine deficient at the time of delivery, their free T4 levels were 0.48 (0.41-0.54) ng/dL with normal thyroid-stimulating hormone (TSH). Iodine levels were thirty-fold higher in extremely low gestational age newborns (ELGAN) exposed to iodine comparing to full terms (p < 0.001), but this effect lasted <1 week. At 1 month of age, ELGAN on PN developed iodine deficiency (p = 0.017) and had high thyroglobulin levels of 187 (156-271) ng/mL. Iodine levels improved with enteral feeds by 2 months of age (p = 0.01). Iodine deficiency is prevalent among pregnant women and ELGAN; in particular, those on PN are at risk of hypothyroidism. Iodine supplementation during pregnancy and postnatally should be considered to avoid iodine deficiency.

Assessment of adrenal function at birth using adrenal glucocorticoid precursor to product ratios to predict short-term neonatal outcomes.

BACKGROUND: Most neonatal outcomes in neonates are related to normal adrenal gland function. Assessment of adrenal function in a sick preterm neonate remains a challenge, thus we hypothesized that adrenal steroid precursors to their product ratios have a direct relationship with neonatal outcomes. METHODS: We studied demographics of pregnancy and neonatal outcomes in 99 mother-infant pairs (24-41 weeks) and assayed 7 glucocorticoid precursors in the cortisol biosynthesis/degradation pathway. We correlated antenatal factors and short-term neonatal outcomes with these precursors and their ratios to assess maturity of individual enzymes. RESULTS: We found no correlation between cortisol levels with antenatal factors and outcomes. Antenatal steroid use impacted several cortisol precursors. 17-OH pregnenolone-to-cortisol ratio at birth was the best predictor of short-term neonatal outcomes, such as hypotension, RDS, IVH and PDA. A cord blood 17-OH pregnenolone:cortisol ratio of <0.21 predicts which neonate will have a normal outcome with a high sensitivity and specificity. CONCLUSIONS: Maternal factors and antenatal steroids impact neonatal adrenal function and leads to maturation of adrenal function. 17-OH pregnenolone:cortisol ratio and not cortisol is the best predictor of adrenal function. Adrenal function can be assessed by evaluating the profile of adrenal steroids.

Assessment of neonatal adrenal size using high resolution 2D ultrasound and its correlation with birth demographics and clinical outcomes.

OBJECTIVE: Assessment of adrenal function in a sick neonate remains a challenge in spite of major advances in neonatal care. We used 2D ultrasound of adrenal glands to assess maturity of adrenal glands in extremely preterm infants and sick term and near term infants. STUDY DESIGN: We collected demographics details of 99 mother-infants pairs (24-41 weeks) and obtained 2D ultrasound scans of adrenal glands in first week of life to measure adrenal volume, fetal zone size, and adrenal to kidney ratios. Relationship between adrenal measurements, antenatal factors, and postnatal outcomes were studied. RESULTS: We reported normative adrenal gland volume data during gestation from 80 appropriate for gestational age (AGA) infants. In a binary analysis, adrenal size was significantly related to gender, race, intrauterine growth restriction (IUGR), maternal chorioamnionitis, and maternal hypertension. Linear regression analysis showed that fetal zone is significantly related to not only gestational age but also chorioamnionitis and later development of intraventricular hemorrhage (IVH). Adrenal volume likewise is also related to gestational age, preeclampsia, and IVH. CONCLUSIONS: Antenatal maternal factors and uterine environment affects adrenal growth and development thus postnatal high resolution 2D US scan of adrenal glands can provide useful information to predict outcomes. This information can complement hormone and adrenocorticotrophic hormone (ACTH) stimulation assays.

Necrotizing enterocolitis leads to disruption of tight junctions and increase in gut permeability in a mouse model.

BACKGROUND: Necrotizing enterocolitis (NEC) is a leading cause of death in preterm infants. Neonates weighing <1500 grams are at the highest risk for acquiring NEC, with a prevalence of nearly 7-10%, mortality up to 30%, and several long-term complications among survivors. Despite advancements in neonatal medicine, this disease remains a challenge to treat. The aim of this study is to investigate the effect of NEC on gut epithelial tight junctions and its barrier function using a NEC mouse model. METHODS: Three-day old C57BL/6 mouse pups were fed with Esbilac formula every 3 hours and then subjected to hypoxia twice daily followed by cold stress. Dam fed pups from the same litters served as controls. Pups were observed and sacrificed 96 hours after the treatments and intestines were removed for experiments. The successful induction of NEC was confirmed by histopathology. Changes in tight junction proteins in NEC intestines were studied by western blotting and immunofluorescent microscopy using specific protein markers. The gut leakage in NEC was visualized using biotin tracer molecules. RESULTS: Our study results demonstrate that we induced NEC in >50% of experimental pups, pups lost nearly 40% of weight and their intestines showed gross changes and microscopic changes associated with NEC. There were inflammatory changes with loss of tight junction barrier function and disruption of tight junction claudin proteins in the intestines of NEC mouse model. We have demonstrated for the first time that NEC intestines develop increased leakiness as visualized by biotin tracer leakage. CONCLUSIONS: NEC leads to breakdown of epithelial barrier due to changes in tight junction proteins with increased leakiness which may explain the transmigration of microbes and microbial products from the gut lumen into the blood stream leading to sepsis like signs clinically witnessed.

Embryonic lethality in mice due to carnitine transporter OCTN2 defect and placental carnitine deficiency.

l-Carnitine plays a crucial role in uptake and subsequent ß-oxidation of long-chain fatty acids in the mitochondria. Placental trophoblast cells oxidize long-chain fatty acids for energy production. Here we present data showing that l-carnitine deficiency due to a defect in the carnitine transporter OCTN2 (SLC22A5) in a mouse model leads to embryonic lethality. Placental levels of l-carnitine are reduced to <10% of normal and deficiency of l-carnitine is associated with markedly reduced expression of several growth factors and transforming growth factor ß (TGF-ß) genes. This report links for the first time reduced l-carnitine levels in the placenta to embryonic lethality.

Anogenital distance is determined during early gestation in humans.

STUDY QUESTION: Does cord blood androgen level obtained at birth affect the AGD in human newborns? SUMMARY ANSWER: In human newborns, though males have a significantly longer AGD compared to females (as early as 22 weeks of gestation) the AGD is not affected by androgen levels at birth in both the sexes. WHAT IS KNOWN ALREADY: Animal studies have reported a critical time period in early fetal life, termed the masculinization programming window (MPW) during which AGD is fixed by in utero androgen action and is unaffected by testosterone levels later during gestation. Thus, AGD may serve as a lifelong biomarker of androgen exposure during this window. This MPW is hypothesized to occur in humans at 8-14 weeks of gestation during which AGD is fixed. The effect of androgens (testosterone) on AGD after the MPW in humans is not known. Furthermore, altered AGD has been associated with various human reproductive health disorders in both males and females. STUDY DESIGN, SIZE, DURATION: A prospective descriptive cohort study was performed using data from randomly selected neonates (n = 205) born at a single center over a period of 1 year (August 2015 to August 2016). PARTICIPANTS/MATERIALS, SETTING, METHODS: AGDs in male (n = 117) and female infants (n = 88) together with penile width, glans girth and stretched penile length were measured by trained caregivers. Gestation ranged from 22 to 41 weeks and infants were examined within 24 h of birth (within 48-72 h in very sick preterm infants after clinical stabilization). AGD-1 was measured from the center of the anus to the posterior base of scrotum in males or to the posterior fourchette in females. AGD-2 was measured from the center of the anus to the anterior base of the penis in males or to the clitoris in females. Sex steroid hormones (testosterone, 17-OH progesterone (17-OHP) and androstenedione) were measured in serum prepared from umbilical cord blood samples taken at birth, using liquid chromatography-tandem mass spectrometry. MAIN RESULTS AND THE ROLE OF CHANCE: Males had a significantly lower gestational age (mean ± SD; 34.6 ± 4.9 versus 36.1 ± 4.1 weeks, P = 0.04), and a significantly longer AGD-1 (mean ± SD; 21.6 ± 6.0 versus 12.7 ± 3.8 mm, P < 0.001) and AGD-2 (41.9 ± 8.7 versus 33.9 ± 7.1 mm, P = 0.004) compared to female infants, respectively. The cord serum testosterone levels were significantly higher for male than female infants [median, interquartile range; 13.0 (7.3, 20.5) versus 4.1 (2.5, 5.9), ng/dl, P < 0.001]. There was no difference in levels of 17-OHP (P = 0.697) or androstenedione (P = 0.601) between the two sexes. On multiple regression analysis after adjusting for potential confounders, none of the AGD's in both males and females correlated with any sex steroid hormonal levels. We also provide normative charts for penile length, penile width and glans girth in preterm and term infants. LIMITATIONS, REASONS FOR CAUTION: No data were collected on family history of genital malformation, infertility or hormonal disorders, parental endocrine-disrupting chemical exposure or diet pattern, any of which might have influenced the AGD and/or sex steroid hormone levels in the offspring. WIDER IMPLICATIONS OF THE FINDINGS: Our results suggest that AGD in humans, like animals, is fixed in early gestation (likely during the hypothesized MPW) and is unaffected by androgen levels thereafter. Thus, AGD can serve as a biomarker of in utero androgen action during early gestation (likely 8-14 weeks) in humans. As such, causes of human newborn and adult reproductive health disorders, such as endocrine disruptors, should be explored during early gestation. However, further larger studies are needed to help corroborate these findings. STUDY FUNDING/COMPETING INTERESTS: No specific funding was obtained for this study, and all authors have no conflict of interest to declare.

Hypoglycemia in the preterm neonate: etiopathogenesis, diagnosis, management and long-term outcomes.

Glucose, like oxygen, is of fundamental importance for any living being and it is the major energy source for the fetus and the neonate during gestation. The placenta ensures a steady supply of glucose to the fetus, while birth marks a sudden change in substrate delivery and a major change in metabolism. Hypoglycemia is one of the most common pathologies encountered in the neonatal intensive care unit and affects a wide range of neonates. Preterm, small for gestational age (GA) and intra-uterine growth restricted neonates are especially vulnerable due to their lack of metabolic reserves and associated co-morbidities. Nearly 30-60% of these high-risk infants are hypoglycemic and require immediate intervention. Preterm neonates are uniquely predisposed to developing hypoglycemia and its associated complications due to their limited glycogen and fat stores, inability to generate new glucose using gluconeogenesis pathways, have higher metabolic demands due to a relatively larger brain size, and are unable to mount a counter-regulatory response to hypoglycemia. In this review we will discuss the epidemiology; pathophysiology; clinical presentation; management and neurodevelopmental outcomes in affected infants and summarize evidence to develop a rational and scientific approach to this common problem.

Transient hypothyroidism in the newborn: to treat or not to treat.

Transient congenital hypothyroidism (CH) refers to a temporary deficiency of thyroid hormone identified after birth, with low thyroxine (T4) and elevated thyrotropin (TSH), which later recovers to improved thyroxine production, typically in first few months of infancy. Approximately 17% to 40% of children diagnosed with CH by newborn screening (NBS) programs were later determined to have transient hypothyroidism. Causes of transient CH are prematurity, iodine deficiency, maternal thyrotropin receptor blocking antibodies, maternal intake of anti-thyroid drugs, maternal or neonatal iodine exposure, loss of function mutations and hepatic hemangiomas. The classic clinical symptoms and signs of CH are usually absent immediately after birth in vast majority of infants due to temporary protection from maternal thyroxine. NBS has been largely successful in preventing intellectual disability by early detection of CH by performing thyroid function tests in infants with abnormal screening results. In this review we present the evidence for decision making regarding treatment vs. withholding treatment in infants with transient CH and present a rational approach to identifying transient CH based on American Academy of Pediatrics (AAP) recommendation.

Prevalence of diabetes and obesity in association with prematurity and growth restriction.

Intrauterine growth restriction (IUGR) is when fetuses and newborn infants have not reached their true growth potential as genetically defined. Fetuses with IUGR develop in a less than ideal environment that leads to epigenetic changes and marks infants' metabolism for the rest of their lives. Epigenetic changes affect insulin-like growth factor-1 (IGF-1) levels and lead to insulin resistance and ultimately to a metabolic syndrome. The metabolic syndrome is a constellation of illnesses that raise one's risk for type 2 diabetes mellitus, coronary artery disease, and ischemic heart disease, including hypertension, dyslipidemia, central obesity, insulin resistance, and inflammation. The association between IUGR or prematurity and long-term insulin resistance, obesity, hypertension, and metabolic syndrome remains unclear. While studies have shown an association, others have not supported such association. If alteration of intrauterine growth can ultimately lead to the development of metabolic derangements in childhood and adulthood, and if such association is true, then early interventions targeting the health of pregnant women will ensure the health of the population to follow.

Impact of Infant-Polysomnography Studies on Discharge Management and Outcomes: A 5 Year Experience from a Tertiary Care Unit.

OBJECTIVE: To evaluate the impact of infant-polysomnography studies performed in the NICU on management and outcomes. STUDY DESIGN: Retrospective study to collect demographics and data on infant-polysomnography studies between Jan 2010 to Dec 2014. RESULTS: 110 premature neonates had polysomnography study performed at 36.9 ± 2.5 weeks post menstrual age. Almost all the studies were read as abnormal and 95% of the studied infants were discharged home on a cardiorespiratory monitor. 20% of the subjects had apnea >20 s, 18% had apnea of 15-20 s and 50% of infants had apnea of 10-15 s. 24.5% infants were discharged home on caffeine, 28% on metoclopramide and 24% on antacids. There were 11 readmissions for apparent life threatening events with no until 6 month-corrected age. There was no association between polysomnography results and readmission. There was a decline in polysomnography studies performed each year. CONCLUSION: Cardiorespiratory monitoring, medications and polysomnography studies do not predict outcomes.

Shorter anogenital distance correlates with the severity of hypospadias in pre-pubertal boys.

STUDY QUESTION: Do pre-pubertal boys with hypospadias have a shorter anogenital distance (AGD) than boys with normal genitalia? SUMMARY ANSWER: AGD is significantly shorter in boys with hypospadias and decreases with the severity of hypospadias. WHAT IS KNOWN ALREADY: Animal studies have shown that androgen disruption and exposure to endocrine disrupting chemicals during a critical time period in early gestation, termed the male programming window (MPW), result in hypospadias and reduced AGD; and the severity of hypospadias correlates with the reduction in AGD. However, this correlation has not been established in humans. STUDY DESIGN, SIZE, DURATION: A prospective descriptive study involving measurement of AGD in pre-pubertal boys (n = 458) presenting to our pediatric urology clinic with hypospadias and normal genitalia was performed over a period of 3 years. PARTICIPANTS/MATERIALS, SETTING, METHODS: AGD was measured in pre-pubertal boys from 5 months to 14 years of age presenting to our clinic with hypospadias (n = 180: four were excluded) and compared with randomly selected boys with normal genitalia (controls, n = 274). Three variants of AGD, from the midpoint of the anus to base of the scrotum (AGD-AS), to the anterior base of penis (AGD-1) and to the posterior base of penis (AGD-2), were measured and assessed for correlation with the severity of hypospadias. Severity of hypospadias was classified as anterior, middle and posterior according to the meatal location. MAIN RESULTS AND THE ROLE OF CHANCE: No significant difference in weight (P = 0.123), age (P = 0.162) or height (P = 0.591) between the two groups was observed. Only AGD-AS was significantly shorter in boys with hypospadias compared with controls (mean ± SD: 40.6 ± 9.7 mm versus 45.6 ± 9.4 mm, P < 0.001). This relation persisted after adjusting AGD for weight, height and age (ß = 0.016, 95% confidence interval: 0.10-0.21; P < 0.001). The Spearman test showed a significant negative correlation for the severity of hypospadias with all the three AGD measures. Analysis of variance between anterior, middle and posterior subgroups showed a significant reduction in mean AGD-AS (P = 0.003) and AGD-2 (P = 0.008). LIMITATIONS, REASONS FOR CAUTION: No data were collected pertaining to in utero exposure to endocrine disrupting chemicals (EDCs) or cigarette smoke, or current diet and environmental exposure to EDCs, which may have influenced the AGD. Family history of genital malformation and use of IVF were not known. There may have been a selection bias as only boys presenting to our clinic were included. WIDER IMPLICATIONS OF THE FINDINGS: The findings suggest that prenatal androgens during early gestation influence development of the male reproductive system and support the existence of a MPW in humans. Of the three AGDs, AGD-AS may be the most reliable biomarker of this in utero androgen action. However, no direct link to any specific exposure leading to shortened AGD in pre-pubertal boys with hypospadias could be determined. Further large scale multi-center studies are needed to understand this association better. STUDY FUNDING/COMPETING INTERESTS: Funding was from the Hypospadias Foundation. No conflicts of interest to disclose.

Relationship between Packed Red Blood Cell Transfusion and Severe Form of Necrotizing Enterocolitis: A Case Control Study.

OBJECTIVE: To determine if packed red blood cell transfusion is associated with onset of necrotizing enterocolitis, and whether withholding feed has any association with it. METHODS: Case records of 100 preterm neonates, (<34 weeks gestation) who developed necrotizing enterocolitis and 99 random age-and gestation-matched controls were evaluated for any blood transfusion 48 h before onset of necrotizing enterocolitis. RESULTS: During the study period 26% infants received packed red blood cell transfusion within 48-hours prior to onset of disease and 84% of these infants were not fed around the time of transfusion. Infants who developed necrotizing enterocolitis after transfusion were older, of lower gestational age, birth weight and more likely to develop stage 3 disease. They had a lower hematocrit at birth and before onset of disease and withholding feeds around transfusion did not prevent necrotizing enterocolitis. Odds of mortality in these infants was 2.83 (95% CI 0.97-8.9) and survivors had no significant difference in incidence of periventricular leukomalacia and length of hospital stay. CONCLUSION: Blood Transfusion associated necrotizing enterocolitis is a severe, mainly surgical form of disease.

Necrotizing enterocolitis in a mouse model leads to widespread renal inflammation, acute kidney injury, and disruption of renal tight junction proteins.

BACKGROUND: Necrotizing enterocolitis (NEC) is a devastating condition affecting premature infants and leads to high mortality and chronic morbidity. Severe form of NEC is associated with acute renal failure, fluid imbalance, hyponatremia, and acidosis. We investigated the effect of NEC on tight junction (TJ) proteins in kidneys using a NEC mouse model to investigate the basis for the observed renal dysfunction. METHODS: NEC was induced in C57BL/6 mice by formula feeding and subjecting them to periods of hypoxia and cold stress. NEC was confirmed by gross and histological examination. We studied various markers of inflammation in kidneys and investigated changes in expression of several TJ proteins and AQP2 using immunofluorecent staining and western blotting. RESULTS: We found markedly increased expression of NFκB, TGFß, and ERK1/2 along with claudin-1, -2, -3, -4, -8, and AQP-2 in NEC kidneys. The membrane localization of claudin-2 was altered in the NEC kidneys and its immunostaining signal at TJ was disrupted. CONCLUSION: NEC led to a severe inflammatory response not only in the gut but also in the kidneys. NEC increased expression of several TJ proteins and caused disruption of claudin-2 in renal tubules. These observed changes can help explain some of the clinical findings observed in NEC.

Enzymes involved in L-carnitine biosynthesis are expressed by small intestinal enterocytes in mice: implications for gut health.

BACKGROUND: Carnitine is essential for mitochondrial ß-oxidation of long-chain fatty acids. Deficiency of carnitine leads to severe gut atrophy, ulceration and inflammation in animal models of carnitine deficiency. Genetic studies in large populations have linked mutations in the carnitine transporters OCTN1 and OCTN2 with Crohn's disease (CD), while other studies at the same time have failed to show a similar association and report normal serum carnitine levels in CD patients. METHODS: In this report, we have studied the expression of carnitine-synthesizing enzymes in intestinal epithelial cells to determine the capability of these cells to synthesize carnitine de novo. We studied expression of five enzymes involved in carnitine biosynthesis, namely 6-N-trimethyllysine dioxygenase (TMLD), 4-trimethylaminobutyraldehyde dehydrogenase (TMABADH), serine hydroxymethyltransferase 1 and 2 (SHMT1 and 2) and γ-butyrobetaine hydroxylase (BBH) by real-time PCR in mice (C3H strain). We also measured activity of γ-BBH in the intestine using an ex vivo assay and localized its expression by in situ hybridization. RESULTS: Our investigations show that mouse intestinal epithelium expresses all five enzymes required for de novo carnitine biosynthesis; the expression is localized mainly in villous surface epithelial cells throughout the intestine. The final rate-limiting enzyme γ-BBH is highly active in the small intestine; its activity was 9.7 ± 3.5 pmol/mg/min, compared to 22.7 ± 7.3 pmol/mg/min in the liver. CONCLUSIONS: We conclude that mouse gut epithelium is able to synthesize carnitine de novo. This capacity to synthesize carnitine in the intestine may play an important role in gut health and can help explain lack of clinical carnitine deficiency signs in subjects with mutations with OCTN transporters.

Carnitine deficiency in OCTN2-/- newborn mice leads to a severe gut and immune phenotype with widespread atrophy, apoptosis and a pro-inflammatory response.

We have investigated the gross, microscopic and molecular effects of carnitine deficiency in the neonatal gut using a mouse model with a loss-of-function mutation in the OCTN2 (SLC22A5) carnitine transporter. The tissue carnitine content of neonatal homozygous (OCTN2(-/-)) mouse small intestine was markedly reduced; the intestine displayed signs of stunted villous growth, early signs of inflammation, lymphocytic and macrophage infiltration and villous structure breakdown. Mitochondrial ß-oxidation was active throughout the GI tract in wild type newborn mice as seen by expression of 6 key enzymes involved in ß-oxidation of fatty acids and genes for these 6 enzymes were up-regulated in OCTN2(-/-) mice. There was increased apoptosis in gut samples from OCTN2(-/-) mice. OCTN2(-/-) mice developed a severe immune phenotype, where the thymus, spleen and lymph nodes became atrophied secondary to increased apoptosis. Carnitine deficiency led to increased expression of CD45-B220(+) lymphocytes with increased production of basal and anti-CD3-stimulated pro-inflammatory cytokines in immune cells. Real-time PCR array analysis in OCTN2(-/-) mouse gut epithelium demonstrated down-regulation of TGF-ß/BMP pathway genes. We conclude that carnitine plays a major role in neonatal OCTN2(-/-) mouse gut development and differentiation, and that severe carnitine deficiency leads to increased apoptosis of enterocytes, villous atrophy, inflammation and gut injury.

Spontaneous development of intestinal and colonic atrophy and inflammation in the carnitine-deficient jvs (OCTN2(-/-)) mice.

Carnitine is essential for transport of long-chain fatty acids into mitochondria for their subsequent beta-oxidation, but its role in the gastrointestinal tract has not been well described. Recently several genetic epidemiologic studies have shown strong association between mutations in carnitine transporter genes OCTN1 and OCTN2 and a propensity to develop Crohn's disease. This study aims to investigate role of carnitine and beta-oxidation in the GI tract. We have studied the gastrointestinal tract effects of carnitine deficiency in a mouse model with loss-of-function mutation in the OCTN2 carnitine transporter. juvenile visceral steatosis (OCTN2(-/-)) mouse spontaneously develops intestinal villous atrophy, breakdown and inflammation with intense lymphocytic and macrophage infiltration, leading to ulcer formation and gut perforation. There is increased apoptosis of jvs (OCTN2(-/-)) gut epithelial cells. We observed an up-regulation of heat shock factor-1 (HSF-1) and several heat shock proteins (HSPs) which are known to regulate OCTN2 gene expression. Intestinal and colonic epithelial cells in wild type mice showed high expression and activity of the enzymes of beta-oxidation pathway. These studies provide evidence of an obligatory role for carnitine in the maintenance of normal intestinal and colonic structure and morphology. Fatty acid oxidation, a metabolic pathway regulated by carnitine-dependent entry of long-chain fatty acids into mitochondrial matrix, is likely essential for normal gut function. Our studies suggest that carnitine supplementation, as a means of boosting fatty acid oxidation, may be therapeutically beneficial in patients with inflammation of the intestinal tract.