Glucocorticoid receptor-PPARα axis in fetal mouse liver prepares neonates for milk lipid catabolism.

In mammals, hepatic lipid catabolism is essential for the newborns to efficiently use milk fat as an energy source. However, it is unclear how this critical trait is acquired and regulated. We demonstrate that under the control of PPARα, the genes required for lipid catabolism are transcribed before birth so that the neonatal liver has a prompt capacity to extract energy from milk upon suckling. The mechanism involves a fetal glucocorticoid receptor (GR)-PPARα axis in which GR directly regulates the transcriptional activation of PPARα by binding to its promoter. Certain PPARα target genes such as Fgf21 remain repressed in the fetal liver and become PPARα responsive after birth following an epigenetic switch triggered by β-hydroxybutyrate-mediated inhibition of HDAC3. This study identifies an endocrine developmental axis in which fetal GR primes the activity of PPARα in anticipation of the sudden shifts in postnatal nutrient source and metabolic demands

Metronidazole Causes Skeletal Muscle Atrophy and Modulates Muscle Chronometabolism.

Antibiotics lead to increased susceptibility to colonization by pathogenic organisms, with different effects on the host-microbiota relationship. Here, we show that metronidazole treatment of specific pathogen-free (SPF) mice results in a significant increase of the bacterial phylum <i>Proteobacteria</i> in fecal pellets. Furthermore, metronidazole in SPF mice decreases hind limb muscle weight and results in smaller fibers in the tibialis anterior muscle. In the gastrocnemius muscle, metronidazole causes upregulation of <i>Hdac4</i> , <i>myogenin</i> , <i>MuRF1</i> , and <i>atrogin1</i> , which are implicated in skeletal muscle neurogenic atrophy. Metronidazole in SPF mice also upregulates skeletal muscle <i>FoxO3</i> , described as involved in apoptosis and muscle regeneration. Of note, alteration of the gut microbiota results in increased expression of the muscle core clock and effector genes <i>Cry2</i> , <i>Ror</i> - <i>β</i> , and <i>E4BP4</i> . <i>PPARγ</i> and one of its important target genes, <i>adiponectin</i> , are also upregulated by metronidazole. Metronidazole in germ-free (GF) mice increases the expression of other core clock genes, such as <i>Bmal1</i> and <i>Per2</i> , as well as the metabolic regulators <i>FoxO1</i> and <i>Pdk4</i> , suggesting a microbiota-independent pharmacologic effect. In conclusion, metronidazole in SPF mice results in skeletal muscle atrophy and changes the expression of genes involved in the muscle peripheral circadian rhythm machinery and metabolic regulation

Intestinal PPARγ signalling is required for sympathetic nervous system activation in response to caloric restriction.

Nuclear receptor PPARγ has been proven to affect metabolism in multiple tissues, and has received considerable attention for its involvement in colon cancer and inflammatory disease. However, its role in intestinal metabolism has been largely ignored. To investigate this potential aspect of PPARγ function, we submitted intestinal epithelium-specific PPARγ knockout mice (iePPARγKO) to a two-week period of 25% caloric restriction (CR), following which iePPARγKO mice retained more fat than their wild type littermates. In attempting to explain this discrepancy, we analysed the liver, skeletal muscle, intestinal lipid trafficking, and the microbiome, none of which appeared to contribute to the adiposity phenotype. Interestingly, under conditions of CR, iePPARγKO mice failed to activate their sympathetic nervous system (SNS) and increase CR-specific locomotor activity. These KO mice also manifested a defective control of their body temperature, which was overly reduced. Furthermore, the white adipose tissue of iePPARγKO CR mice showed lower levels of both hormone-sensitive lipase, and its phosphorylated form. This would result from impaired SNS signalling and possibly cause reduced lipolysis. We conclude that intestinal epithelium PPARγ plays an essential role in increasing SNS activity under CR conditions, thereby contributing to energy mobilization during metabolically stressful episodes

Innate Immune Responses of Pulmonary Epithelial Cells to Burkholderia pseudomallei Infection

10.1371/journal.pone.0007308PLoS ONE410

Congenital segmental emphysema: an evolving lesion

<p>Congenital segmental emphysema (CSE) is a newly-recognised sub-type of congenital parenchymal lung anomaly. It is characterised by antenatal detection and post-natal evolution from an initially solid segmental appearance to a hyperlucent and hyperinflated segment.<br> A retrospective review of a single-centre tertiary referral database between Jan 1994 and Dec 2007 was performed.<br> 130 infants had antenatally detected lung anomalies, and of these 12 (9.2%) infants (initially labelled as congenital cystic adenomatoid malformation (CCAM)), showed features better defined as CSE. The lesions were described antenatally as non-progressive microcystic (n=6), hyperechogenic (n=2) or both (n=2). Early post-natal CT scans showed areas of solid segmental parenchyma, initial hyperlucency or microcysts. Subsequent CT imaging, however, showed evolution to segmental hyperlucency in areas previously solid and in 2 cases a central bronchocele was noted. Ten children underwent resectional surgery (segmentectomy n=4, lobectomy n=6) at a median age of 1 (range 0.4-5.2) year and the gross appearance of the resected specimen confirmed hyperinflated (not cystic) segments. Histological review showed localised abnormally dilated alveolar spaces in 7 cases. Adjacent areas consistent with type 2 CCAM were also seen (n=3).<br> CSE lies within the spectrum of both CCAM and sequestration but there is a definite post-natal evolution and volume change which presage symptoms. This may be associated with segmental bronchial atresia and progressive air trapping via collateral airways such as the interalveolar pores of Kohn.</p