A role for gangliosides and β1‐integrin in the motility of olfactory ensheathing glia

Olfactory ensheathing glia (OEG) are found in the olfactory mucosa, nerve and bulb, and provide in vivo ensheathment for the unmyelinated olfactory axons within the central and peripheral nervous system domains. OEG cells are able to migrate long distances within the neuropil of the central nervous system. Because gangliosides such as 9‐O‐acetyl GD3 have crucial regulatory roles in neuronal migration during development, we analyzed whether OEG in organotypical cultures are revealed by anti‐9‐O‐acetyl GD3 and/or gangliosides are recognized by the A2B5 antibody (G‐A2B5), and whether these gangliosides are involved in OEG migration. Our results showed that all OEG migrating out of a section of olfactory bulb onto a laminin substrate bound to the 9‐O‐acetyl GD3 and A2B5 antibodies, and that 2′,3′‐cyclic nucleotide phosphodiesterase (CNPase) colocalized with 9‐O‐acetyl GD3 and with G‐A2B5. Additionally, we showed that the immune blockade of 9‐O‐acetyl GD3 or G‐A2B5 reduced the migration of OEG on laminin, and that 9‐O‐acetyl GD3 and G‐A2B5 colocalized with the β1‐integrin subunit. We also confirmed the phenotype of in‐vitro‐grown OEG cells derived from adult rats, showing that they express CNPase, and also α‐smooth muscle actin, which is not expressed by Schwann cells. Our data showed that the gangliosides 9‐O‐acetyl GD3 and G‐A2B5 participate in the migratory activity of OEG cells, and that the β1‐integrin subunit colocalizes with these gangliosides. These results suggest a new role for β1‐integrin and gangliosides in the polarized migration of OEG cells, and provide new information on the molecules controlling OEG motility and behavior.     

Intestinal smooth muscle is required for patterning the enteric nervous system

The development of the enteric nervous system (ENS) and intestinal smooth muscle occurs in a spatially and temporally correlated manner, but how they influence each other is unknown. In the developing mid‐gut of the chick embryo, we find that α‐smooth muscle actin expression, indicating early muscle differentiation, occurs after the arrival of migrating enteric neural crest‐derived cells (ENCCs). In contrast, hindgut smooth muscle develops prior to ENCC arrival. Smooth muscle development is normal in experimentally aganglionic hindguts, suggesting that proper development and patterning of the muscle layers does not rely on the ENS. However, inhibiting early smooth muscle development severely disrupts ENS patterning without affecting ENCC proliferation or apoptosis. Our results demonstrate that early intestinal smooth muscle differentiation is required for patterning the developing ENS.     

Spatiotemporal mapping of vascularization and innervation in the fetal murine intestine

Background : In mice, the intestinal tube develops from the splanchopleure before embryonic day 9.5. Subsequent patterning of nerves and blood vessels is critical for normal digestive function. A hierarchical branching vascular network allows for efficient nutrient absorption, while the complex enteric nervous system regulates intestinal motility as well as secretion, absorption, and blood flow. Despite the well‐recognized significance of these systems, the precise mechanisms by which they develop have not been clearly established in mammals. Results : Using a novel whole‐mount immunohistochemical protocol, we visualize the pattern of intestinal neurovascular development in mice between embryonic day 10.5 and birth. In particular, we focus on the development and remodeling of the enteric vascular plexus, the migration and organization of enteric neural crest‐derived cells, and the integration of peripheral sympathetic nerves with the enteric nervous system. These correlative data lead us to hypothesize a functional interaction between migrating neural crest‐derived cells and endothelial cells of the primary capillary plexus, as well as a subsequent interaction between developing peripheral autonomic nerves and differentiated neural crest‐derived cells. Conclusions: These studies provide useful anatomical data for continuing investigations on the functional mechanisms underlying intestinal organogenesis. Developmental Dynamics 244:56–68, 2015. Published 2014. This article is a U.S. Government work and is in the public domain in the USA     

Nervous system development in normal and atresic chick embryo intestine: an immunohistochemical study

Intestinal motility disorders are a common complication after surgery for neonatal intestinal atresia. Although intestinal atresia causes alterations in the enteric nervous system, especially in its inner structures (nervous fibers in the mucosa, submucous and deep muscular plexuses), how these alterations develop is unclear. The chick model is a useful research tool for investigating the ontogenesis of the enteric nervous system and the pathogenesis of congenital bowel diseases. More information is needed on the overlap between the developing enteric nervous system and intestinal atresia. Because vasoactive intestinal polypeptide and substance P are typical intestinal neuropeptides, and vasoactive intestinal polypeptide acts as a modulator in neurodevelopment and an inhibitor of smooth muscle cell proliferation, our aim in this study was to investigate the distribution of their immunoreactivity in the developing enteric nervous system of normal and experimental chick models. We studied gut specimens excised from normal chick embryos (aged 12–20 days) and experimental chick embryos (aged 15–20 days) that underwent surgical intervention on day 12 to induce intestinal atresia (atresic embryos) or simply to grasp the bowel loop (sham-operated embryos). In normal chick embryos we showed vasoactive intestinal polypeptide and substance P immunoreactivity from day 12 in the submucous and myenteric plexuses. The distribution of peptide immunoreactivity differed markedly in atresic and normal or sham-operated gut embryos. These differences especially affected the inner structures of the enteric nervous system of specimens proximal to atresia and were related to the severity of dilation. Because nerve structures in the gut wall mucosa and submucous and deep muscular plexuses play a role in motility control and stretch sensation in the intestinal wall, our findings in the chick embryo may help to explain how gut motility disorders develop after surgery for neonatal intestinal atresia.     

CCR7‐mediated migration in the thymus controls γδ T‐cell development

αβ T‐cell development and selection proceed while thymocytes successively migrate through distinct regions of the thymus. For γδ T cells, the interplay of intrathymic migration and cell differentiation is less well understood. Here, we crossed C‐C chemokine receptor (CCR)7‐deficient (Ccr7^?/?) and CCR9‐deficient mice (Ccr9^?/?) to mice with a TcrdH2BeGFP reporter background to investigate the impact of thymic localization on γδ T‐cell development. γδ T‐cell frequencies and numbers were decreased in CCR7‐deficient and increased in CCR9‐deficient mice. Transfer of CCR7‐ or CCR9‐deficient BM into irradiated C57BL/6 WT recipients reproduced these phenotypes, pointing toward cell‐intrinsic migration defects. Monitoring recent thymic emigrants by intrathymic labeling allowed us to identify decreased thymic γδ T‐cell output in CCR7‐deficient mice. In vitro, CCR7‐deficient precursors showed normal γδ T‐cell development. Immunohistology revealed that CCR7 and CCR9 expression was important for γδ T‐cell localization within thymic medulla or cortex, respectively. However, γδ T‐cell motility was unaltered in CCR7‐ or CCR9‐deficient thymi. Together, our results suggest that proper intrathymic localization is important for normal γδ T‐cell development.     

Loss of dystrophin and the microtubule‐binding protein ELP‐1 causes progressive paralysis and death of adult C. elegans

EMAP‐like proteins (ELPs) are conserved microtubule‐binding proteins that function during cell division and in the behavior of post‐mitotic cells. In Caenorhabditis elegans, ELP‐1 is broadly expressed in many cells and tissues including the touch receptor neurons and body wall muscle. Within muscle, ELP‐1 is associated with a microtubule network that is closely opposed to the integrin‐based adhesion sites called dense bodies. To examine ELP‐1 function, we utilized an elp‐1 RNA interference assay and screened for synthetic interactions with mutated adhesion site proteins. We reveal a synthetic lethal relationship between ELP‐1 and the dystrophin‐like protein, DYS‐1. Reduction of ELP‐1 in a dystrophin [dys‐1(cx18)] mutant results in adult animals with motility defects, splayed and hypercontracted muscle with altered cholinergic signaling. Worms fill with vesicles, become flaccid, and die. We conclude that ELP‐1 is a genetic modifier of a C. elegans model of muscular dystrophy. Developmental Dynamics, 2009. © 2009 Wiley‐Liss, Inc.     

Developmental Expression Profile of the CXCL12γ Isoform: Insights Into its Tissue‐Specific Role

The CXCL12γ chemokine arises by alternative splicing from Cxcl12, an highly conserved gene that plays pivotal, non‐redundant roles during development. The interaction of the highly cationic carboxy‐terminal (C‐ter) domain of CXCL12γ with glycosaminoglycans (GAG) critically determines the biological properties of this chemokine. Indeed, CXCL12γ isoform displays sustained in vivo recruitment of leukocytes and endothelial progenitor cells as compared to other CXCL12 isoforms. Despite the important, specific roles of CXCL12γ in vivo, the current knowledge about its distribution in embryo and adult tissues is scarce. In this study, we have characterized by both RT‐PCR and immunohistochemistry the expression profile and tissue distribution of CXCL12γ, which showed a distinct mRNA expression pattern during organogenesis that correlates with the specific expression of the CXCL12 γ protein in several tissues and cell types during development. Our results support the biological relevance of CXCL12 γ in vivo, and shed light on the specific roles that this novel isoform could play in muscle development and vascularization as well as on the regulation of essential homeostatic functions during the embryonic development. Anat Rec, 292:891–901, 2009. © 2009 Wiley‐Liss, Inc.     

Three-dimensional slice cultures from murine fetal gut for investigations of the enteric nervous system.

Three-dimensional intestinal cultures offer new possibilities for the examination of growth potential, analysis of time specific gene expression, and spatial cellular arrangement of enteric nervous system in an organotypical environment. We present an easy to produce in vitro model of the enteric nervous system for analysis and manipulation of cellular differentiation processes. Slice cultures of murine fetal colon were cultured on membrane inserts for up to 2 weeks without loss of autonomous contractility. After slice preparation, cultured tissue reorganized within the first days in vitro. Afterward, the culture possessed more than 35 cell layers, including high prismatic epithelial cells, smooth muscle cells, glial cells, and neurons analyzed by immunohistochemistry. The contraction frequency of intestinal slice culture could be modulated by the neurotransmitter serotonin and the sodium channel blocker tetrodotoxin. Coculture experiments with cultured neurospheres isolated from enhanced green fluorescent protein (eGFP) transgenic mice demonstrated that differentiating eGFP-positive neurons were integrated into the intestinal tissue culture. This slice culture model of enteric nervous system proved to be useful for studying cell-cell interactions, cellular signaling, and cell differentiation processes in a three-dimensional cell arrangement.     

Foetal and placental 11β‐HSD2: a hub for developmental programming

Foetal growth restriction (FGR), reflective of an adverse intrauterine environment, confers a significantly increased risk of perinatal mortality and morbidity. In addition, low birthweight associates with adult diseases including hypertension, metabolic dysfunction and behavioural disorders. A key mechanism underlying FGR is exposure of the foetus to glucocorticoids which, while critical for foetal development, in excess can reduce foetal growth and permanently alter organ structure and function, predisposing to disease in later life. Foetal glucocorticoid exposure is regulated, at least in part, by the enzyme 11β‐hydroxysteroid dehydrogenase type 2 (11β‐HSD2), which catalyses the intracellular inactivation of glucocorticoids. This enzyme is highly expressed within the placenta at the maternal–foetal interface, limiting the passage of glucocorticoids to the foetus. Expression of 11β‐HSD2 is also high in foetal tissues, particularly within the developing central nervous system. Down‐regulation or genetic deficiency of placental 11β‐HSD2 is associated with significant reductions in foetal growth and birth weight, and programmed outcomes in adulthood. To unravel the direct significance of 11β‐HSD2 for developmental programming, placental function, neurodevelopment and adult behaviour have been extensively investigated in a mouse knockout of 11β‐HSD2. This review highlights the evidence obtained from this mouse model for a critical role of feto‐placental 11β‐HSD2 in determining the adverse programming outcomes.     

Histological phenotypes of enteric smooth muscle disease causing functional intestinal obstruction in childhood

Aims: Functional intestinal obstruction or chronic idiopathic intestinal pseudo-obstruction is due to defects either in the enteric innervation or in intestinal smooth muscle. We have studied full-thickness intestinal biopsies from 27 patients with functional intestinal obstruction due to enteric smooth muscle disease by routine histology and electron microscopy together with histochemical and immunohistochemical techniques to detect changes in the intestinal smooth muscle. Methods and results: Two patients appeared to have an acquired intestinal myopathy as a result of an autoimmune process. In 25 the disorders were congenital, of these seven had segmental abnormalities limited to the rectum and distal colon and 18 had a diffuse disease affecting both the small and large bowel. We identified five apparent histological phenotypes of enteric muscle disease, three of which represent abnormalities in morphogenesis resulting in alterations in intestinal muscle layering and two exemplify intrinsic myocyte defects and/or changes in the extracellular matrix. Conclusions: Careful phenotyping of these patients is important in devising optimal treatment and in understanding the underlying defect as well as the possible genetic mechanisms resulting in these abnormalities. Recognition of autoimmune smooth muscle disease is helpful, since making the diagnosis influences the patient's management.     

Acute colonic ischaemia in rats results in long‐term structural changes without alterations of colonic sensitivity

Colonic ischaemia and mast cells have been involved in the pathophysiology of the functional gastrointestinal disorder irritable bowel syndrome, although the cause–effect relationships remain unknown. We assessed long‐term histopathological and functional changes associated to an acute ischaemic episode (1 h) of the colon, followed by 8‐week recovery, in rats. Functional colonic alterations [sensitivity during colorectal distension (CRD), compliance and propulsive motility] were assessed regularly during the recovery. Colonic histopathology (presence of inflammation, morphometric alterations and variations in neuronal density in the enteric nervous system) 8‐week postischaemia was assessed. Following ischaemia, none of the functional parameters tested (motility, sensitivity and compliance) were affected. At necropsy, the colon presented an overall normal appearance with an increase in weight of the ischaemic area (mg/cm: 99 ± 6; P < 0.05 vs. control: 81 ± 4 or sham ischaemia: 81 ± 3). Histopathological evaluations revealed the presence of a local infiltrate of mast cells in the area of ischaemia (nb of mast cells: 142 ± 50; P < 0.05 vs. control, 31 ± 14 or sham ischaemia: 40 ± 16), without other significant alterations. Animals subjected to colonic ischaemia and treated 8 weeks later with the mast cell degranulator, compound 48/80, showed no changes in CRD‐related pain responses. These studies show that acute colonic ischaemia is associated with the presence of a long‐term local infiltration of mast cells, located within the serosa and muscle layers, despite the absence of functional changes, including colonic sensitivity. Considering the important pathophysiological functions of mast cells, the observed mast cell infiltration may be involved in ischaemia‐induced functional changes yet to be characterized.     

Lung‐resident γδ T cells and their roles in lung diseases

γδ T cells are greatly enriched in mucosal and epithelial sites, such as the skin, respiratory, digestive and reproductive tracts, and they are defined as tissue‐resident immune cells. In these tissues, the characteristics and biological roles of γδ T cells are distinguished from each other. The lungs represent the most challenging immunological dilemma for the host, and they have their own effective immune system. The abundance of γδ T cells, an estimated 8–20% of resident pulmonary lymphocytes in the lung, maintains lung tissue homeostasis. In this review, we summarize the recent research progress regarding lung‐resident γδ T cells, including their development, residency and immune characteristics, and discuss the involvement of γδ T cells in infectious diseases of the lung, including bacterial, viral and fungal infections; lung allergic disease; lung inflammation and fibrosis; and lung cancer.     

Intraganglionic macrophages: a new population of cells in the enteric ganglia

The enteric nervous system shares embryological, morphological, neurochemical, and functional features with the central nervous system. In addition to neurons and glia, the CNS includes a third component, microglia, which are functionally and immunophenotypically similar to macrophages, but a similar cell type has not previously been identified in enteric ganglia. In this study we identify a population of macrophages in the enteric ganglia, intermingling with the neurons and glia. These intraganglionic macrophages (IMs) are highly ramified and express the hematopoietic marker CD45, major histocompatibility complex (MHC) class II antigen, and chB6, a marker specific for B cells and microglia in avians. These IMs do not express antigens typically associated with T cells or dendritic cells. The CD45⁺/ChB6⁺/MHCII⁺ signature supports a hematopoietic origin and this was confirmed using intestinal chimeras in GFP‐transgenic chick embryos. The presence of green fluorescent protein positive (GFP⁺⁾/CD45⁺ cells in the intestinal graft ENS confirms that IMs residing within enteric ganglia have a hematopoietic origin. IMs are also found in the ganglia of CSF1R^GFP chicken and CX3CR1^GFP mice. Based on the expression pattern and location of IMs in avians and rodents, we conclude that they represent a novel non‐neural crest‐derived microglia‐like cell population within the enteric ganglia.     

Hyperpolarization‐activated cation and T‐type calcium ion channel expression in porcine and human renal pacemaker tissues

Renal pacemaker activity triggers peristaltic upper urinary tract contractions that propel waste from the kidney to the bladder, a process prone to congenital defects that are the leading cause of pediatric kidney failure. Recently, studies have discovered that hyperpolarization‐activated cation (HCN) and T‐type calcium (TTC) channel conductances underlie murine renal pacemaker activity, setting the origin and frequency and coordinating upper urinary tract peristalsis. Here, we determined whether this ion channel expression is conserved in the porcine and human urinary tracts, which share a distinct multicalyceal anatomy with multiple pacemaker sites. Double chromagenic immunohistochemistry revealed that HCN isoform 3 is highly expressed at the porcine minor calyces, the renal pacemaker tissues, whereas the kidney and urinary tract smooth muscle lacked this HCN expression. Immunofluorescent staining demonstrated that HCN⁺ cells are integrated within the porcine calyx smooth muscle, and that they co‐express TTC channel isoform Cav3.2. In humans, the anatomic structure of the minor calyx pacemaker was assayed via hematoxylin and eosin analyses, and enabled the visualization of the calyx smooth muscle surrounding adjacent papillae. Strikingly, immunofluorescence revealed that HCN3⁺/Cav3.2⁺ cells are also localized to the human minor calyx smooth muscle. Collectively, these data have elucidated a conserved molecular signature of HCN and TTC channel expression in porcine and human calyx pacemaker tissues. These findings provide evidence for the mechanisms that can drive renal pacemaker activity in the multi‐calyceal urinary tract, and potential causes of obstructive uropathies.     

11β‐Hydroxysteroid dehydrogenase type 1 within muscle protects against the adverse effects of local inflammation

Muscle wasting is a common feature of inflammatory myopathies. Glucocorticoids (GCs), although effective at suppressing inflammation and inflammatory muscle loss, also cause myopathy with prolonged administration. 11β‐Hydroxysteroid dehydrogenase type 1 (11β‐HSD1) is a bidirectional GC‐activating enzyme that is potently upregulated by inflammation within mesenchymal‐derived tissues. We assessed the regulation of this enzyme with inflammation in muscle, and examined its functional impact on muscle. The expression of 11β‐HSD1 in response to proinflammatory stimuli was determined in a transgenic murine model of chronic inflammation (TNF‐Tg) driven by overexpression of tumour necrosis factor (TNF)‐α within tissues, including muscle. The inflammatory regulation and functional consequences of 11β‐HSD1 expression were examined in primary cultures of human and murine myotubes and human and murine muscle biopsies ex vivo. The contributions of 11β‐HSD1 to muscle inflammation and wasting were assessed in vivo with the TNF‐Tg mouse on an 11β‐HSD1 null background. 11β‐HSD1 was significantly upregulated within the tibialis anterior and quadriceps muscles from TNF‐Tg mice. In human and murine primary myotubes, 11β‐HSD1 expression and activity were significantly increased in response to the proinflammatory cytokine TNF‐α (mRNA, 7.6‐fold, p < 0.005; activity, 4.1‐fold, p < 0.005). Physiologically relevant levels of endogenous GCs activated by 11β‐HSD1 suppressed proinflammatory cytokine output (interkeukin‐6, TNF‐α, and interferon‐γ), but had little impact on markers of muscle wasting in human myotube cultures. TNF‐Tg mice on an 11β‐11β‐HSD1 knockout background developed greater muscle wasting than their TNF‐Tg counterparts (27.4% less; p < 0.005), with smaller compacted muscle fibres and increased proinflammatory gene expression relative to TNF‐Tg mice with normal 11β‐HSD1 activity. This study demonstrates that inflammatory stimuli upregulate 11β‐HSD1 expression and GC activation within muscle. Although concerns have been raised that excess levels of GCs may be detrimental to muscle, in this inflammatory TNF‐α‐driven model, local endogenous GC activation appears to be an important anti‐inflammatory response that protects against inflammatory muscle wasting in vivo. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

Types of nerves in the enteric nervous system

The enteric nervous system is one of the three divisions of the autonomic nervous system, the others being the sympathetic and parasympathetic. In contrast to the other divisions, it can perform many functions independently of the central nervous system. It consists of ganglionated plexuses, their connections with each other, and nerve fibres which arise from the plexuses and supply the muscle, blood vessels and mucosa of the gastrointestinal tract. The enteric nervous system contains a large number of neurons, approximately 10⁷ to 10⁸. About ten or more distinct types of enteric neurons have been distinguished on electrical, pharmacological, histochemical, biochemical and ultrastructural grounds as well as on the basis of their modes of action. Both excitatory and inhibitory nerves supply the muscle and there are inhibitory and excitatory interneurons within the enteric plexuses. There are also enteric nerves which supply intestinal glands and blood vessels, but these receive less emphasis in this commentary.Correlations between groups of neurons defined on different criteria are poor and in many cases the physiological roles of the nerves are not known. The functions of noradrenergic nerves which are of extrinsic origin are reasonably well understood, but cholinergic nerves in the intestine are the only intrinsic nerves for which both the transmitter and to some extent the functions are known. In the case of non-cholinergic, non-noradrenergic enteric inhibitory nerves, the functions are understood but the transmitter is yet to be determined, both adenosine 5′-triphosphate and vasoactive intestinal polypeptide having been proposed. Other nerves have been defined pharmacologically (non-cholinergic excitatory nerves to neurons and muscle, intrinsic inhibitory inputs to neurons, and enteric, non-cholinergic vasodilator nerves) and histochemically (intrinsic amine-handling neurons and separate neurons containing peptides: substance P, somatostatin, enkephalins, vasoactive intestinal polypeptide, gastrin cholecystokinin tetrapeptide, bombesin, neurotensin and probably other peptides). Little is known of the functions of these nerves, although a number of proposals which have been made are discussed.     

Analysis of conserved residues in the βpat‐3 cytoplasmic tail reveals important functions of integrin in multiple tissues

Integrin cytoplasmic tails contain motifs that link extracellular information to cell behavior such as cell migration and contraction. To investigate the cell functions mediated by the conserved motifs, we created mutations in the Caenorhabditis elegans βpat‐3 cytoplasmic tail. The β1D (⁷⁹⁹FK⁸⁰⁰), NPXY, tryptophan (⁷⁸⁴W), and threonine (⁷⁹⁷TT⁷⁹⁸) motifs were disrupted to identify their functions in vivo. Animals expressing integrins with disrupted NPXY motifs were viable, but displayed distal tip cell migration and ovulation defects. The conserved threonines were required for gonad migration and contraction as well as tail morphogenesis, whereas disruption of the β1D and tryptophan motifs produced only mild defects. To abolish multiple conserved motifs, a β1C‐like variant, which results in a frameshift, was constructed. The βpat‐3(β1C) transgenic animals showed cold‐sensitive larval arrests and defective muscle structure and gonad migration and contraction. Our study suggests that the conserved NPXY and TT motifs play important roles in the tissue‐specific function of integrin. Developmental Dynamics 239:763–772, 2010. © 2010 Wiley‐Liss, Inc.