BackgroundNecrotizing enterocolitis (NEC) is a devastating neonatal gastrointestinal disease that primarily affects premature infants. It is characterized by bowel inflammation and necrosis. In spite of extensive research, there has been little progress in decreasing the incidence or mortality of NEC over the past three decades. The exact etiology of NEC has not been identified. However, it is believed to result from an inappropriate immune response to gut microbiota. Using 454-pyrosequencing analyses of 16S rRNA genes that were PCR-amplified from stool DNA specimens, we compared the gut microbiota of infants with NEC to matched controls without NEC. The infants with NEC were then categorized into three subgroups based on severity: mild, severe, and lethal. We compared the microbiota among these subgroups and between each severity group and appropriate controls.ResultsBacterial diversity and the relative abundance of Actinobacteria and Clostridia were significantly lower in NEC specimens compared to controls. The absence of Clostridia was significantly associated with NEC. Microbial diversity and Clostridia abundance and prevalence decreased with increasing severity of NEC.ConclusionsLow bacterial diversity in stool specimens may be indicative of NEC and the severity of NEC. The low bacterial diversity, and the lack of Clostridia in lethal specimens, could indicate that the presence of a diverse bacterial population in the gut as well as the presence of taxa such as Clostridia may play a role in attenuating inflammation leading to NEC.Electronic supplementary materialThe online version of this article (doi:10.1186/s40168-015-0075-8) contains supplementary material, which is available to authorized users.

Although not designed to look specifically at the effect of H2-blockers on the incidence of NEC, our study suggests that their use lowers fecal microbial diversity and shifts the microfloral pattern toward Proteobacteria. These alterations in fecal microbiota may predispose the vulnerable immature gut to necrotizing enterocolitis and suggest prudence in the use of H2-blockers in the premature infant.

Necrotizing enterocolitis is the most common gastrointestinal emergency in neonates. The etiology is considered multifactorial. Risk factors include prematurity, enteral feeding, hypoxia, and bacterial colonization. The etiologic role of viruses is unclear. We present a case of necrotizing enterocolitis associated with cytomegalovirus and Proteobacteria in a 48-day-old, ex-premature infant and discuss the effects of potential viral-bacterial interactions on host susceptibility to this disease.

IL-10 is an anti-inflammatory cytokine that suppresses synthesis of proinflammatory cytokines and their receptors. Here we tested the possibility that TNFα-induced hormone resistance in myoblasts might be overcome by IL-10. We found that IL-10 restores myogenesis by suppressing the ability of exogenous TNFα to inhibit IGF-I-induced myogenin. This protection occurs without decreasing global activity of TNF receptors since IL-10 does not impair TNFα-induced IL-6 synthesis or ERK1/2 phosphorylation. Instead, IL-10 acts to prevent TNFα-induced phosphorylation of JNK. These findings demonstrate that IL-10 serves a previously unrecognized protective role in muscle progenitors by overcoming TNFα-induced resistance to IGF-I.

Thrombin is a multifunctional serine protease whose activity is regulated in the extravasculature by an extracellular inhibitor, protease nexin-1. Because protease nexin-1 expression has been shown to be regulated during skeletal muscle cell differentiation, we reasoned that thrombin inactivation may be an important requirement for this developmental process. To test this hypothesis, we examined the effects of thrombin on differentiating C2C12 myoblasts. We report here that myogenesis, as scored by myotube formation, is considerably delayed by thrombin. This regulation correlated with delayed expression of myogenin and p21 CIP1/WAF1 , both considered critical components of the skeletal muscle cell differentiation program. Regulation occurred at the RNA level, indicating that the effect of thrombin is either transcriptional or post-transcriptional. Furthermore, we present evidence suggesting that this regulation is mediated by the thrombin receptor. Although thrombin is mitogenic for certain cell types, we found that delay of myogenesis in C2C12 cells did not involve a mitogenic signal. Taken together, these results imply that inhibition of the serine protease thrombin may be required for proper progression through the myogenic differentiation program. The data point to potentially important roles that thrombin and protease nexin-1 may play during skeletal muscle development.Thrombin is a multifunctional serine protease that regulates both vascular and extravascular cellular processes. In the extravasculature thrombin is mitogenic for fibroblasts, smooth muscle cells, and astroglia cells (1-3). In addition, thrombin causes neurite retraction in neurons (4) and promotes cell death in certain cell types (5, 6). Most if not all of the actions of thrombin are mediated by a seven-transmembrane domain, G-protein-coupled receptor that is activated by a thrombin cleavage event in the extracellular domain of the receptor (7,8). Proteolysis generates a new N terminus that acts as a tethered peptide ligand, binding to a site in the receptor, and activating a signal transduction cascade (9).Thrombin activity is tightly regulated in the extravasculature by the serine protease inhibitor protease nexin-1 (PN-1), 1 also referred to as glia-derived nexin (10, 11). PN-1 expression is relatively high in brain, and because it is regulated during injury it is thought to protect neuronal cells from the potentially harmful effects of serine proteases (12-14). PN-1 may also play a role in synapse formation in skeletal muscle because it is secreted from muscle fibers at the neuromuscular junction where acetylcholine receptors are expressed, and PN-1 blocks the proteolytic action of thrombin, which mediates activitydependent synapse reduction (15, 16).Formation of the neuromuscular junction is preceded by the differentiation of skeletal muscle cells, an event morphologically characterized as the fusion of mononucleated myoblasts into multinucleated myotubes. Differentiation is largely controlled by the myogenic basic helix-loop-helix fami...