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Histopathological Defects in Intestine in Severe Spinal Muscular Atrophy Mice Are Improved by Systemic Antisense Oligonucleotide Treatment.

Sintusek P, Catapano F, Angkathunkayul N, Marrosu E, Parson SH, Morgan JE, Muntoni F, Zhou H - PLoS ONE (2016)

Bottom Line: We also assessed the therapeutic response of GI histopathology to systemic administration of morpholino antisense oligonucleotide (AON) designed to increase SMN protein expression.Significant anatomical and histopathological abnormalities, with striking reduction of vascular density, overabundance of enteric neurons and increased macrophage infiltration, were detected in the small intestine in SMA mice.We conclude that the observed GI histopathological phenotypes and functional defects observed in these SMA mice are strongly linked to SMN deficiency which can be rescued by systemic administration of AON.

View Article: PubMed Central - PubMed

Affiliation: Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom.

ABSTRACT
Gastrointestinal (GI) defects, including gastroesophageal reflux, constipation and delayed gastric emptying, are common in patients with spinal muscular atrophy (SMA). Similar GI dysmotility has been identified in mouse models with survival of motor neuron (SMN) protein deficiency. We previously described vascular defects in skeletal muscle and spinal cord of SMA mice and we hypothesized that similar defects could be involved in the GI pathology observed in these mice. We therefore investigated the gross anatomical structure, enteric vasculature and neurons in the small intestine in a severe mouse model of SMA. We also assessed the therapeutic response of GI histopathology to systemic administration of morpholino antisense oligonucleotide (AON) designed to increase SMN protein expression. Significant anatomical and histopathological abnormalities, with striking reduction of vascular density, overabundance of enteric neurons and increased macrophage infiltration, were detected in the small intestine in SMA mice. After systemic AON treatment in neonatal mice, all the abnormalities observed were significantly restored to near-normal levels. We conclude that the observed GI histopathological phenotypes and functional defects observed in these SMA mice are strongly linked to SMN deficiency which can be rescued by systemic administration of AON. This study on the histopathological changes in the gastrointestinal system in severe SMA mice provides further indication of the complex role that SMN plays in multiple tissues and suggests that at least in SMA mice restoration of SMN production in peripheral tissues is essential for optimal outcome.

No MeSH data available.


Related in: MedlinePlus

Systemic delivery of PMO25 increased SMN2 exon 7 inclusion and SMN protein expression in intestine.(A) Representative image of reverse transcriptional polymerase chain reaction (PCR) showed the partial increase of full-length SMN2 in SMA mice after PMO25 treatment. (B) Quantitative real-time PCR of full-length SMN2 to Δ7 SMN2 transcript ratio. (C) Western blotting assay of human SMN protein in intestine tissues from SMA and PMO25 treated SMA mice. β–tubulin was used as loading control. (D) Semi-quantification of SMN protein relative to tubulin control. Data were normalized to the ratio of SMN/tubulin in untreated SMA mice. (N = 3, *P< 0.05)
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pone.0155032.g006: Systemic delivery of PMO25 increased SMN2 exon 7 inclusion and SMN protein expression in intestine.(A) Representative image of reverse transcriptional polymerase chain reaction (PCR) showed the partial increase of full-length SMN2 in SMA mice after PMO25 treatment. (B) Quantitative real-time PCR of full-length SMN2 to Δ7 SMN2 transcript ratio. (C) Western blotting assay of human SMN protein in intestine tissues from SMA and PMO25 treated SMA mice. β–tubulin was used as loading control. (D) Semi-quantification of SMN protein relative to tubulin control. Data were normalized to the ratio of SMN/tubulin in untreated SMA mice. (N = 3, *P< 0.05)

Mentions: We have previously shown that systemic administration of PMO25 successfully rescues severe SMA mice [10]. A significant increase in SMN2 exon 7 inclusion and SMN protein were detected in the central nervous system after PMO25 was delivered subcutaneously in severe SMA mice on PND0, in keeping with the incomplete blood brain barrier function in newborn mice [10]. In addition, we have also demonstrated that regular systemic administration of low-dose PMO25 at later stage can still benefit SMA mice with intermediate phenotypes, and suggest that restoration of SMN in peripheral systems, in addition to CNS restoration, is important for SMA treatment [30]. To determine the efficiency of AON therapy on SMN expression in intestine, SMN2 exon 7 inclusion and the expression of SMN protein in duodenal segments were assessed by quantitative real-time PCR and western blotting, respectively. The ratio of full-length SMN2 to Δ7 SMN2 transcripts in intestine was significantly increased after systemic PMO25 treatment (P = 0.014; Fig 6A and 6B). SMN protein was increased approximately 2-fold in intestine after PMO25 treatment (Fig 6C and 6D).


Histopathological Defects in Intestine in Severe Spinal Muscular Atrophy Mice Are Improved by Systemic Antisense Oligonucleotide Treatment.

Sintusek P, Catapano F, Angkathunkayul N, Marrosu E, Parson SH, Morgan JE, Muntoni F, Zhou H - PLoS ONE (2016)

Systemic delivery of PMO25 increased SMN2 exon 7 inclusion and SMN protein expression in intestine.(A) Representative image of reverse transcriptional polymerase chain reaction (PCR) showed the partial increase of full-length SMN2 in SMA mice after PMO25 treatment. (B) Quantitative real-time PCR of full-length SMN2 to Δ7 SMN2 transcript ratio. (C) Western blotting assay of human SMN protein in intestine tissues from SMA and PMO25 treated SMA mice. β–tubulin was used as loading control. (D) Semi-quantification of SMN protein relative to tubulin control. Data were normalized to the ratio of SMN/tubulin in untreated SMA mice. (N = 3, *P< 0.05)
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4862622&req=5

pone.0155032.g006: Systemic delivery of PMO25 increased SMN2 exon 7 inclusion and SMN protein expression in intestine.(A) Representative image of reverse transcriptional polymerase chain reaction (PCR) showed the partial increase of full-length SMN2 in SMA mice after PMO25 treatment. (B) Quantitative real-time PCR of full-length SMN2 to Δ7 SMN2 transcript ratio. (C) Western blotting assay of human SMN protein in intestine tissues from SMA and PMO25 treated SMA mice. β–tubulin was used as loading control. (D) Semi-quantification of SMN protein relative to tubulin control. Data were normalized to the ratio of SMN/tubulin in untreated SMA mice. (N = 3, *P< 0.05)
Mentions: We have previously shown that systemic administration of PMO25 successfully rescues severe SMA mice [10]. A significant increase in SMN2 exon 7 inclusion and SMN protein were detected in the central nervous system after PMO25 was delivered subcutaneously in severe SMA mice on PND0, in keeping with the incomplete blood brain barrier function in newborn mice [10]. In addition, we have also demonstrated that regular systemic administration of low-dose PMO25 at later stage can still benefit SMA mice with intermediate phenotypes, and suggest that restoration of SMN in peripheral systems, in addition to CNS restoration, is important for SMA treatment [30]. To determine the efficiency of AON therapy on SMN expression in intestine, SMN2 exon 7 inclusion and the expression of SMN protein in duodenal segments were assessed by quantitative real-time PCR and western blotting, respectively. The ratio of full-length SMN2 to Δ7 SMN2 transcripts in intestine was significantly increased after systemic PMO25 treatment (P = 0.014; Fig 6A and 6B). SMN protein was increased approximately 2-fold in intestine after PMO25 treatment (Fig 6C and 6D).

Bottom Line: We also assessed the therapeutic response of GI histopathology to systemic administration of morpholino antisense oligonucleotide (AON) designed to increase SMN protein expression.Significant anatomical and histopathological abnormalities, with striking reduction of vascular density, overabundance of enteric neurons and increased macrophage infiltration, were detected in the small intestine in SMA mice.We conclude that the observed GI histopathological phenotypes and functional defects observed in these SMA mice are strongly linked to SMN deficiency which can be rescued by systemic administration of AON.

View Article: PubMed Central - PubMed

Affiliation: Dubowitz Neuromuscular Centre, Institute of Child Health, University College London, London, United Kingdom.

ABSTRACT
Gastrointestinal (GI) defects, including gastroesophageal reflux, constipation and delayed gastric emptying, are common in patients with spinal muscular atrophy (SMA). Similar GI dysmotility has been identified in mouse models with survival of motor neuron (SMN) protein deficiency. We previously described vascular defects in skeletal muscle and spinal cord of SMA mice and we hypothesized that similar defects could be involved in the GI pathology observed in these mice. We therefore investigated the gross anatomical structure, enteric vasculature and neurons in the small intestine in a severe mouse model of SMA. We also assessed the therapeutic response of GI histopathology to systemic administration of morpholino antisense oligonucleotide (AON) designed to increase SMN protein expression. Significant anatomical and histopathological abnormalities, with striking reduction of vascular density, overabundance of enteric neurons and increased macrophage infiltration, were detected in the small intestine in SMA mice. After systemic AON treatment in neonatal mice, all the abnormalities observed were significantly restored to near-normal levels. We conclude that the observed GI histopathological phenotypes and functional defects observed in these SMA mice are strongly linked to SMN deficiency which can be rescued by systemic administration of AON. This study on the histopathological changes in the gastrointestinal system in severe SMA mice provides further indication of the complex role that SMN plays in multiple tissues and suggests that at least in SMA mice restoration of SMN production in peripheral tissues is essential for optimal outcome.

No MeSH data available.


Related in: MedlinePlus