RESUMO
Inherited deficiency of thymidine phosphorylase (TP), encoded by TYMP, leads to a rare disease with multiple mitochondrial DNA (mtDNA) abnormalities, mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). However, the impact of TP deficiency on lysosomes remains unclear, which are important for mitochondrial quality control and nucleic acid metabolism. Muscle biopsy tissue and skin fibroblasts from MNGIE patients, patients with m.3243 A > G mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and healthy controls (HC) were collected to perform mitochondrial and lysosomal functional analyses. In addition to mtDNA abnormalities, compared to controls distinctively reduced expression of LAMP1 and increased mitochondrial content were detected in the muscle tissue of MNGIE patients. Skin fibroblasts from MNGIE patients showed decreased expression of LAMP2, lowered lysosomal acidity, reduced enzyme activity and impaired protein degradation ability. TYMP knockout or TP inhibition in cells can also induce the similar lysosomal dysfunction. Using lysosome immunoprecipitation (Lyso- IP), increased mitochondrial proteins, decreased vesicular proteins and V-ATPase enzymes, and accumulation of various nucleosides were detected in lysosomes with TP deficiency. Treatment of cells with high concentrations of dThd and dUrd also triggers lysosomal dysfunction and disruption of mitochondrial homeostasis. Therefore, the results provided evidence that TP deficiency leads to nucleoside accumulation in lysosomes and lysosomal dysfunction, revealing the widespread disruption of organelles underlying MNGIE.
Assuntos
DNA Mitocondrial , Fibroblastos , Lisossomos , Mitocôndrias , Encefalomiopatias Mitocondriais , Nucleosídeos , Timidina Fosforilase , Humanos , Lisossomos/metabolismo , Timidina Fosforilase/metabolismo , Timidina Fosforilase/deficiência , Timidina Fosforilase/genética , Encefalomiopatias Mitocondriais/metabolismo , Encefalomiopatias Mitocondriais/patologia , Encefalomiopatias Mitocondriais/genética , Fibroblastos/metabolismo , Fibroblastos/patologia , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Mitocôndrias/metabolismo , Nucleosídeos/metabolismo , Pseudo-Obstrução Intestinal/metabolismo , Pseudo-Obstrução Intestinal/patologia , Pseudo-Obstrução Intestinal/enzimologia , Pseudo-Obstrução Intestinal/genética , Oftalmoplegia/metabolismo , Oftalmoplegia/patologia , Oftalmoplegia/congênito , Distrofia Muscular Oculofaríngea/metabolismo , Distrofia Muscular Oculofaríngea/patologia , Masculino , Feminino , Pele/patologia , Pele/metabolismo , Proteína 2 de Membrana Associada ao Lisossomo/metabolismoRESUMO
Visceral myopathy is a life-threatening disease characterized by muscle weakness in the bowel, bladder, and uterus. Mutations in smooth muscle γ-actin (ACTG2) are the most common cause of the disease, but the mechanisms by which the mutations alter muscle function are unknown. Here, we examined four prevalent ACTG2 mutations (R40C, R148C, R178C, and R257C) that cause different disease severity and are spread throughout the actin fold. R178C displayed premature degradation, R148C disrupted interactions with actin-binding proteins, R40C inhibited polymerization, and R257C destabilized filaments. Because these mutations are heterozygous, we also analyzed 50/50 mixtures with wild-type (WT) ACTG2. The WT/R40C mixture impaired filament nucleation by leiomodin 1, and WT/R257C produced filaments that were easily fragmented by smooth muscle myosin. Smooth muscle tropomyosin isoform Tpm1.4 partially rescued the defects of R40C and R257C. Cryo-electron microscopy structures of filaments formed by R40C and R257C revealed disrupted intersubunit contacts. The biochemical and structural properties of the mutants correlate with their genotype-specific disease severity.
Assuntos
Actinas , Mutação de Sentido Incorreto , Humanos , Actinas/metabolismo , Actinas/genética , Pseudo-Obstrução Intestinal/genética , Pseudo-Obstrução Intestinal/metabolismo , Pseudo-Obstrução Intestinal/patologia , Microscopia Crioeletrônica , Músculo Liso/metabolismo , Músculo Liso/patologia , Modelos Moleculares , Ligação ProteicaRESUMO
The enteric nervous system (ENS) controls gastrointestinal (GI) motility, and defects in ENS development underlie pediatric GI motility disorders. In disorders such as Hirschsprung's disease (HSCR), pediatric intestinal pseudo-obstruction (PIPO), and intestinal neuronal dysplasia type B (INDB), ENS structure is altered with noted decreased neuronal density in HSCR and reports of increased neuronal density in PIPO and INDB. The developmental origin of these structural deficits is not fully understood. Here, we review the current understanding of ENS development and pediatric GI motility disorders incorporating new data on ENS structure. In particular, emerging evidence demonstrates that enteric neurons are patterned into circumferential stripes along the longitudinal axis of the intestine during mouse and human development. This novel understanding of ENS structure proposes new questions about the pathophysiology of pediatric GI motility disorders. If the ENS is organized into stripes, could the observed changes in enteric neuron density in HSCR, PIPO, and INDB represent differences in the distribution of enteric neuronal stripes? We review mechanisms of striped patterning from other biological systems and propose how defects in striped ENS patterning could explain structural deficits observed in pediatric GI motility disorders.
Assuntos
Sistema Nervoso Entérico , Motilidade Gastrointestinal , Doença de Hirschsprung , Sistema Nervoso Entérico/fisiopatologia , Sistema Nervoso Entérico/patologia , Humanos , Animais , Doença de Hirschsprung/patologia , Doença de Hirschsprung/fisiopatologia , Camundongos , Neurônios/patologia , Neurônios/metabolismo , Pseudo-Obstrução Intestinal/patologia , Pseudo-Obstrução Intestinal/fisiopatologia , Padronização CorporalRESUMO
Eosinophilic myenteric ganglionitis (EMG) is a rare pathologic finding within the Auerbach myenteric plexus characterized by eosinophilic infiltration on light microscopy. The plexus's ultimate obliteration results in chronic intestinal pseudo-obstruction (CIPO). EMG is almost exclusively seen in the pediatric population. The diagnosis of EMG is made through full-thickness rectal biopsy and EMG is not detectable through routine screening measures such as imaging or colonoscopy. The current treatment modality for this disorder is not standardized, and has often been treated with systemic steroids given its eosinophilic involvement. This case presents a 73-year-old male with chronic constipation presenting with new obstipation in the setting of recent orthopedic intervention requiring outpatient opioids. Admission radiographs were consistent with sigmoid volvulus. Following endoscopic detorsion, exploratory laparotomy revealed diffuse colonic dilation and distal ischemia requiring a Hartmann's procedure. Surgical pathology revealed EMG, increasing the complexity of subsequent surgical decision-making after his urgent operation.
Assuntos
Pseudo-Obstrução Intestinal , Volvo Intestinal , Doenças do Colo Sigmoide , Masculino , Humanos , Criança , Idoso , Volvo Intestinal/complicações , Volvo Intestinal/diagnóstico , Volvo Intestinal/cirurgia , Colo , Pseudo-Obstrução Intestinal/patologia , Pseudo-Obstrução Intestinal/cirurgia , Plexo Mientérico/patologia , Colonoscopia , Doenças do Colo Sigmoide/complicações , Doenças do Colo Sigmoide/diagnósticoRESUMO
Enteric glial cells are emerging as critical players in the regulation of intestinal motility, secretion, epithelial barrier function, and gut homeostasis in health and disease. Enteric glia react to intestinal inflammation by converting to a 'reactive glial phenotype' and enteric gliosis, contributing to neuroinflammation, enteric neuropathy, bowel motor dysfunction and dysmotility, diarrhea or constipation, 'leaky gut', and visceral pain. The focus of the minireview is on the impact of inflammation on enteric glia reactivity in response to diverse insults such as intestinal surgery, ischemia, infections (C. difficile infection, HIV-Tat-induced diarrhea, endotoxemia and paralytic ileus), GI diseases (inflammatory bowel diseases, diverticular disease, necrotizing enterocolitis, colorectal cancer) and functional GI disorders (postoperative ileus, chronic intestinal pseudo-obstruction, constipation, irritable bowel syndrome). Significant progress has been made in recent years on molecular pathogenic mechanisms of glial reactivity and enteric gliosis, resulting in enteric neuropathy, disruption of motility, diarrhea, visceral hypersensitivity and abdominal pain. There is a growing number of glial molecular targets with therapeutic implications that includes receptors for interleukin-1 (IL-1R), purines (P2X2R, A2BR), PPARα, lysophosphatidic acid (LPAR1), Toll-like receptor 4 (TLR4R), estrogen-ß receptor (ERß) adrenergic α-2 (α-2R) and endothelin B (ETBR), connexin-43 / Colony-stimulating factor 1 signaling (Cx43/CSF1) and the S100ß/RAGE signaling pathway. These exciting new developments are the subject of the minireview. Some of the findings in pre-clinical models may be translatable to humans, raising the possibility of designing future clinical trials to test therapeutic application(s). Overall, research on enteric glia has resulted in significant advances in our understanding of GI pathophysiology.
Assuntos
Clostridioides difficile , Sistema Nervoso Entérico , Gastroenteropatias , Pseudo-Obstrução Intestinal , Humanos , Recém-Nascido , Gliose/metabolismo , Sistema Nervoso Entérico/patologia , Gastroenteropatias/terapia , Gastroenteropatias/metabolismo , Gastroenteropatias/patologia , Neuroglia/metabolismo , Inflamação/metabolismo , Dor Abdominal/metabolismo , Dor Abdominal/patologia , Motilidade Gastrointestinal , Diarreia/metabolismo , Diarreia/patologia , Constipação Intestinal/metabolismo , Pseudo-Obstrução Intestinal/terapia , Pseudo-Obstrução Intestinal/metabolismo , Pseudo-Obstrução Intestinal/patologiaRESUMO
Chronic intestinal pseudo-obstruction (CIPO) is a rare condition characterized by intestinal obstruction without any restriction or occlusion, that represents the most severe form of gastrointestinal dysmotility. Here we established the induced pluripotent stem cell line FDCHi008-A from PBMCs of a 4-month infant with CIPO, which provides a patient-specific in vitro model to explore the underlying pathogenesis of pediatric intestinal pseudo-obstruction.
Assuntos
Células-Tronco Pluripotentes Induzidas , Pseudo-Obstrução Intestinal , Humanos , Lactente , Criança , Células-Tronco Pluripotentes Induzidas/patologia , Pseudo-Obstrução Intestinal/etiologia , Pseudo-Obstrução Intestinal/patologia , Doença CrônicaRESUMO
Filamin A (FLNA) is a cytoplasmic actin binding protein, recently shown to be expressed as a long and short isoform. Mutations in FLNA are associated with a wide spectrum of disorders, including an X-linked form of chronic intestinal pseudo-obstruction (CIPO). However, the role of FLNA in intestinal development and function is largely unknown. In this study, we show that FLNA is expressed in the muscle layer of the small intestine from early human fetal stages. Expression of FLNA variants associated with CIPO, blocked expression of the long flna isoform and led to an overall reduction of RNA and protein levels. As a consequence, contractility of human intestinal smooth muscle cells was affected. Lastly, our transgenic zebrafish line showed that the flna long isoform is required for intestinal elongation and peristalsis. Histological analysis revealed structural and architectural changes in the intestinal smooth muscle of homozygous fish, likely triggered by the abnormal expression of intestinal smooth muscle markers. No defect in the localization or numbers of enteric neurons was observed. Taken together, our study demonstrates that the long FLNA isoform contributes to intestinal development and function. Since loss of the long FLNA isoform does not seem to affect the enteric nervous system, it likely results in a myopathic form of CIPO, bringing new insights to disease pathogenesis.
Assuntos
Pseudo-Obstrução Intestinal , Peixe-Zebra , Animais , Humanos , Filaminas/genética , Filaminas/metabolismo , Pseudo-Obstrução Intestinal/genética , Pseudo-Obstrução Intestinal/patologia , Intestinos/patologia , Isoformas de Proteínas/genética , Peixe-Zebra/genética , Peixe-Zebra/metabolismo , Animais Geneticamente ModificadosRESUMO
BACKGROUND: Megacystis microcolon intestinal hypoperistalsis syndrome (MMIHS) is a rare and serious congenital disorder with poor outcomes, where a heterozygous missense mutation is present in the ACTG2 gene. Here, we aimed to investigate the pathogenesis of ACTG2 in MMIHS. METHODS: A cohort with 20 patients with MMIHS was screened. Actg2R257C heterozygous mutant mice were generated using the CRISPR/Cas9 system. Gastrointestinal (GI) motility, voluntary urination, collagen gel contraction, and G-actin/F-actin analysis were performed. KEY RESULTS: The R257C variant of ACTG2 most frequently occurred in patients with MMIHS and demonstrated the typical symptoms of MMIHS. Actg2R257C heterozygous mutant mice had dilated intestines and bladders. The functional assay showed a prolonged total time of GI transit and decreased urine spot area. Collagen gel contraction assay and G-actin/F-actin analysis indicated that mutant mice showed reduced area of contraction of smooth muscle cells (SMCs) and impaired actin polymerization. CONCLUSIONS & INFERENCES: A mouse model demonstrating MMIHS-like symptoms was generated. The Actg2R257C heterozygous variant impairs SMCs contraction by interfering with actin polymerization, leading to GI motility disorders.
Assuntos
Anormalidades Múltiplas , Actinas , Pseudo-Obstrução Intestinal , Animais , Camundongos , Anormalidades Múltiplas/genética , Anormalidades Múltiplas/patologia , Actinas/genética , Colo/patologia , Pseudo-Obstrução Intestinal/genética , Pseudo-Obstrução Intestinal/patologia , Fenótipo , HumanosRESUMO
Enteric neuropathy underlies long-term gastrointestinal (GI) dysfunction associated with several pathological conditions. Our previous studies have demonstrated that structural and functional changes in the enteric nervous system (ENS) result in persistent alterations of intestinal functions long after the acute insult. These changes lead to aberrant immune response and chronic dysregulation of the epithelial barrier. Damage to the ENS is prognostic of disease progression and plays an important role in the recurrence of clinical manifestations. This suggests that the ENS is a viable therapeutic target to alleviate chronic intestinal dysfunction. Our recent studies in preclinical animal models have progressed into the development of novel therapeutic strategies for the treatment of enteric neuropathy in various chronic GI disorders. We have tested the anti-inflammatory and neuroprotective efficacy of novel compounds targeting specific molecular pathways. Ex vivo studies in human tissues freshly collected after resection surgeries provide an understanding of the molecular mechanisms involved in enteric neuropathy. In vivo treatments in animal models provide data on the efficacy and the mechanisms of actions of the novel compounds and their combinations with clinically used therapies. These novel findings provide avenues for the development of safe, cost-effective, and highly efficacious treatments of GI disorders.
Assuntos
Sistema Nervoso Entérico , Gastroenteropatias , Pseudo-Obstrução Intestinal , Animais , Humanos , Sistema Nervoso Entérico/patologia , Gastroenteropatias/tratamento farmacológico , Pseudo-Obstrução Intestinal/patologia , Resultado do Tratamento , Modelos AnimaisRESUMO
BACKGROUND: Dominant gamma-smooth muscle actin gene (ACTG2) variants cause clinically diverse forms of visceral myopathy. Many patients undergo intestinal resection or biopsy before identification of their genetic defect. The pathology of ACTG2-variant visceral myopathy has not been evaluated systematically. METHODS: Glass slides, ultrastructural images, molecular genetic reports, and clinical records from 16 patients with pathogenic (15) or likely pathogenic (1) ACTG2 variants were reviewed and compared with surgical specimens from controls (no evidence of a primary myopathy or pseudo-obstruction due to Hirschsprung disease) and published descriptions. RESULTS: The variable clinical manifestations in our cohort matched those in the literature. Only non-specific light and electron microscopic findings observed in non-myopathic controls were encountered in 13 of 16 patients. The remaining 3 patients harbored hyalinized cytoplasmic inclusions in smooth muscle cells and 1 of them had polyglucosan bodies in the muscularis propria. CONCLUSIONS: Apart from hyalinized inclusions, which were only observed in 3/16 patients, intestinal pathology in the majority of patients with ACTG2 variants is not indicative of an underlying visceral myopathy. Molecular testing should be considered even when no diagnostic intestinal pathology is identified.
Assuntos
Pseudo-Obstrução Intestinal , Miopatias Congênitas Estruturais , Humanos , Actinas/genética , Pseudo-Obstrução Intestinal/diagnóstico , Pseudo-Obstrução Intestinal/genética , Pseudo-Obstrução Intestinal/patologia , Bexiga Urinária , Miopatias Congênitas Estruturais/patologia , Colo/patologiaRESUMO
The leiomodin1 (LMOD1) gene, encoding a potent actin nucleator, was recently reported as a potential pathogenic gene of megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS, OMIM 619362). However, only a single patient has been reported to have LMOD1 mutations, and the underlying pathogenic mechanism remains unknown. Here, we described a male infant with LMOD1 mutations presenting typical symptoms of pediatric intestinal pseudo-obstruction (PIPO) but without megacystis and microcolon. Two compound heterozygous missense variants (c.1106C>T, p.T369M; c.1262G>A, p.R421H) were identified, both affecting highly conserved amino acid residues within the second actin-binding site (ABS2) domain of LMOD1. Expression analysis showed that both variants resulted in significantly reduced protein amounts, especially for p.T369M, which was almost undetectable. The reduction was only partially rescued by the proteasome inhibitor MG-132, indicating that there might be proteasome-independent pathways involved in the degradation of the mutant proteins. Molecular modeling showed that variant p.T369M impaired the local protein conformation of the ABS2 domain, while variant p.R421H directly impaired the intermolecular interaction between ABS2 and actin. Accordingly, both variants significantly damaged LMOD1-mediated actin nucleation. These findings provide further human genetic evidence supporting LMOD1 as a pathogenic gene underlying visceral myopathy including PIPO and MMIHS, strengthen the critical role of ABS2 domain in LMOD1-mediated actin nucleation, and moreover, reveal an unrecognized role of ABS2 in protein stability.
Assuntos
Actinas/metabolismo , Autoantígenos/genética , Proteínas do Citoesqueleto/genética , Pseudo-Obstrução Intestinal/genética , Mutação com Perda de Função , Autoantígenos/química , Autoantígenos/metabolismo , Sítios de Ligação , Proteínas do Citoesqueleto/química , Proteínas do Citoesqueleto/metabolismo , Células HeLa , Humanos , Lactente , Pseudo-Obstrução Intestinal/metabolismo , Pseudo-Obstrução Intestinal/patologia , Masculino , Simulação de Acoplamento Molecular , Complexo de Endopeptidases do Proteassoma/metabolismo , Ligação Proteica , Estabilidade ProteicaRESUMO
BACKGROUND: A fundamental understanding of the enteric nervous system in normal and diseased states is limited by the lack of standard measures of total enteric neuron number. The adult zebrafish is a useful model in this context as it is amenable to in toto imaging of the intestine. We leveraged this to develop a technique to image and quantify all enteric neurons within the adult zebrafish intestine and applied this method to assess the relationship between intestinal length and total enteric neuron number. METHODS: Dissected adult zebrafish intestines were immunostained in wholemount, optically cleared with refractive index-matched solution, and then imaged in tiles using light-sheet microscopy. Imaging software was used to stitch the tiles, and the full image underwent automated cell counting. Total enteric neuron number was assessed in relation to intestinal length using linear regression modeling. KEY RESULTS: Whole gut imaging of the adult zebrafish intestine permits the visualization of endogenous and immunohistochemistry-derived fluorescence throughout the intestine. While enteric neuron distribution is heterogeneous between intestinal segments, total enteric neuron number positively correlates with intestinal length. CONCLUSIONS & INFERENCES: Imaging of all enteric neurons within the adult vertebrate intestine is possible in models such as the zebrafish. In this study, we apply this to demonstrate a positive correlation between enteric neuron number and intestinal length. Quantifying total enteric numbers will facilitate future studies of enteric neuropathies and ENS structure in animal models and potentially in biopsied tissue samples.
Assuntos
Sistema Nervoso Entérico , Pseudo-Obstrução Intestinal , Animais , Sistema Nervoso Entérico/fisiologia , Pseudo-Obstrução Intestinal/patologia , Intestinos/patologia , Neurônios , Peixe-ZebraRESUMO
Digestive Chagas disease (DCD) is an enteric neuropathy caused by Trypanosoma cruzi infection. The mechanism of pathogenesis is poorly understood and the lack of a robust, predictive animal model has held back research. We screened a series of mouse models using gastrointestinal tracer assays and in vivo infection imaging systems to discover a subset exhibiting chronic digestive transit dysfunction and significant retention of faeces in both sated and fasted conditions. The colon was a specific site of both tissue parasite persistence, delayed transit and dramatic loss of myenteric neurons as revealed by whole-mount immunofluorescence analysis. DCD mice therefore recapitulated key clinical manifestations of human disease. We also exploited dual reporter transgenic parasites to home in on locations of rare chronic infection foci in the colon by ex vivo bioluminescence imaging and then used fluorescence imaging in tissue microdomains to reveal co-localisation of infection and enteric nervous system lesions. This indicates that long-term T. cruzi-host interactions in the colon drive DCD pathogenesis, suggesting that the efficacy of anti-parasitic chemotherapy against chronic disease progression warrants further pre-clinical investigation.
Assuntos
Doença de Chagas/complicações , Modelos Animais de Doenças , Trato Gastrointestinal/parasitologia , Pseudo-Obstrução Intestinal/patologia , Trypanosoma cruzi/patogenicidade , Animais , Doença de Chagas/parasitologia , Doença Crônica , Feminino , Pseudo-Obstrução Intestinal/etiologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Camundongos SCIDRESUMO
BACKGROUND: The breakpoint cluster region (BCR) is a protein that originally forms a fusion protein with c-Abl tyrosine kinase and induces leukemia. Researchers have shown that BCR is enriched in the central nervous system and may contribute to neurological disorders. We aimed to investigate the physiological function of BCR in neural development in the gastrointestinal (GI) tract and brain. METHODS: Whole-exome sequencing was used to screen for mutations in the BCR. Bcr knockout mice (Bcr-/- , ΔExon 2-22) were generated using the CRISPR/Cas9 system. Transit of carmine red dye and glass bead expulsion assays were used to record total and proximal GI transit and distal colonic transit. KEY RESULTS: In an infant with pediatric intestinal pseudo-obstruction, we found a heterozygous de novo mutation (NM_004327.3:c.3072+1G>A) in BCR. Bcr deficiency mice (Bcr-/- ) exhibited growth retardation and impaired gastrointestinal motility. Bcr-/- mice had a prolonged average total GI transit time with increased distal colonic transit and proximal GI transit in isolation. Morphology analysis indicated that Bcr-/- mice had a less number of neurons in the submucosal plexus and myenteric plexus. Bcr-/- mice exhibited apparent structural defects in the brain, particularly in the cortex. Additionally, Bcr- depletion in the mouse cortex altered the expression of Ras homologous (Rho) family small GTPases. CONCLUSIONS AND INFERENCES: BCR mutations are associated with intestinal obstruction in children. Loss of Bcr can cause intestinal dysmotility and brain developmental defects may via regulation of Rho GTPases.
Assuntos
Encéfalo/metabolismo , Gastroenteropatias/genética , Motilidade Gastrointestinal/genética , Pseudo-Obstrução Intestinal/genética , Proteínas Proto-Oncogênicas c-bcr/genética , Animais , Feminino , Gastroenteropatias/metabolismo , Gastroenteropatias/fisiopatologia , Trato Gastrointestinal/metabolismo , Trato Gastrointestinal/fisiopatologia , Trânsito Gastrointestinal/genética , Humanos , Pseudo-Obstrução Intestinal/metabolismo , Pseudo-Obstrução Intestinal/patologia , Camundongos , Camundongos Knockout , Neurônios/metabolismo , Proteínas Proto-Oncogênicas c-bcr/metabolismoRESUMO
Visceral myopathies (VMs) encompass a spectrum of disorders characterized by chronic disruption of gastrointestinal function, with or without urinary system involvement. Pathogenic missense variation in smooth muscle γ-actin gene (ACTG2) is associated with autosomal dominant VM. Whole-genome sequencing of an infant presenting with chronic intestinal pseudo-obstruction revealed a homozygous 187 bp (c.589_613 + 163del188) deletion spanning the exon 6-intron 6 boundary within ACTG2 The patient's clinical course was marked by prolonged hospitalizations, multiple surgeries, and intermittent total parenteral nutrition dependence. This case supports the emerging understanding of allelic heterogeneity in ACTG2-related VM, in which both biallelic and monoallelic variants in ACTG2 are associated with gastrointestinal dysfunction of similar severity and overlapped clinical presentation. Moreover, it illustrates the clinical utility of rapid whole-genome sequencing, which can comprehensively and precisely detect different types of genomic variants including small deletions, leading to guidance of clinical care decisions.
Assuntos
Actinas/genética , Genótipo , Pseudo-Obstrução Intestinal/diagnóstico , Pseudo-Obstrução Intestinal/genética , Humanos , Íleus , Lactente , Pseudo-Obstrução Intestinal/patologia , Masculino , Linhagem , Resultado do Tratamento , Sequenciamento Completo do GenomaRESUMO
Parkinson's disease (PD) is associated with neuronal damage in the brain and gut. This work compares changes in the enteric nervous system (ENS) of commonly used mouse models of PD that exhibit central neuropathy and a gut phenotype. Enteric neuropathy was assessed in five mouse models: peripheral injection of MPTP; intracerebral injection of 6-OHDA; oral rotenone; and mice transgenic for A53T variant human α-synuclein with and without rotenone. Changes in the ENS of the colon were quantified using pan-neuronal marker, Hu, and neuronal nitric oxide synthase (nNOS) and were correlated with GI function. MPTP had no effect on the number of Hu+ neurons but was associated with an increase in Hu+ nuclear translocation (P < 0.04). 6-OHDA lesioned mice had significantly fewer Hu+ neurons/ganglion (P < 0.02) and a reduced proportion of nNOS+ neurons in colon (P < 0.001). A53T mice had significantly fewer Hu+ neurons/area (P < 0.001) and exhibited larger soma size (P < 0.03). Treatment with rotenone reduced the number of Hu+ cells/mm2 in WT mice (P < 0.006) and increased the proportion of Hu+ translocated cells in both WT (P < 0.02) and A53T mice (P < 0.04). All PD models exhibited a degree of enteric neuropathy, the extent and type of damage to the ENS, however, was dependent on the model.
Assuntos
Trato Gastrointestinal/patologia , Pseudo-Obstrução Intestinal/patologia , Doença de Parkinson/patologia , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina , Doença Aguda , Animais , Contagem de Células , Doença Crônica , Colo/efeitos dos fármacos , Colo/patologia , Modelos Animais de Doenças , Fezes , Gânglios/efeitos dos fármacos , Gânglios/patologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Neurônios/efeitos dos fármacos , Neurônios/patologia , Óxido Nítrico Sintase Tipo I/metabolismo , Oxidopamina , Fenótipo , Rotenona/farmacologiaRESUMO
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a multi-system disorder caused by several homozygous or compound heterozygous mutations, mostly in the nuclear gene of TYMP. Our current knowledge on the underlying pathology of the disease is derived through the study of about 200 cases of different ethnicities. Clinical presentations include severe cachexia, weakness, ptosis, diplopia, abdominal cramps or digestive tract disorders, hearing impairment, and paresthesia.Herein, we aim to present five novel mutations of the nuclear gene of TYMP in six Iranian patients diagnosed with MNGIE. In our population, age at the time of diagnosis was 18 to 49 years, while the onset of the symptoms varied from 13 to 20 years. We detected two pathogenic non-frameshift nonsense premature stop codon mutations (c.1013C > A, and c.130C > T), one variant of uncertain significance (VUS) non-frameshift missense mutation (c.345G > T), one likely pathogenic frameshift insertion (c.801_802insCGCG), and one likely benign homozygous non-frameshift deletion (c.1176_1187del) from two siblings. Our findings also confirm the autosomal recessive inheritance pattern of MNGIE in the Iranian population. The lack of knowledge in the area of nuclear gene-modifier genes shadows the genotype-phenotype relationships of MNGIE.
Assuntos
Pseudo-Obstrução Intestinal/genética , Distrofia Muscular Oculofaríngea/genética , Oftalmoplegia/congênito , Fenótipo , Timidina Fosforilase/genética , Adolescente , Códon sem Sentido , Feminino , Genes Recessivos , Humanos , Pseudo-Obstrução Intestinal/patologia , Irã (Geográfico) , Masculino , Distrofia Muscular Oculofaríngea/patologia , Oftalmoplegia/genética , Oftalmoplegia/patologia , Timidina Fosforilase/metabolismo , Adulto JovemRESUMO
Visceral smooth muscle is a crucial component of the walls of hollow organs like the gut, bladder, and uterus. This specialized smooth muscle has unique properties that distinguish it from other muscle types and facilitate robust dilation and contraction. Visceral myopathies are diseases where severe visceral smooth muscle dysfunction prevents efficient movement of air and nutrients through the bowel, impairs bladder emptying, and affects normal uterine contraction and relaxation, particularly during pregnancy. Disease severity exists along a spectrum. The most debilitating defects cause highly dysfunctional bowel, reduced intrauterine colon growth (microcolon), and bladder-emptying defects requiring catheterization, a condition called megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS). People with MMIHS often die early in childhood. When the bowel is the main organ affected and microcolon is absent, the condition is known as myopathic chronic intestinal pseudo-obstruction (CIPO). Visceral myopathies like MMIHS and myopathic CIPO are most commonly caused by mutations in contractile apparatus cytoskeletal proteins. Here, we review visceral myopathy-causing mutations and normal functions of these disease-associated proteins. We propose molecular, cellular, and tissue-level models that may explain clinical and histopathological features of visceral myopathy and hope these observations prompt new mechanistic studies.
Assuntos
Citoesqueleto/genética , Pseudo-Obstrução Intestinal/diagnóstico , Músculo Liso/patologia , Citoesqueleto/patologia , Humanos , Pseudo-Obstrução Intestinal/genética , Pseudo-Obstrução Intestinal/patologia , MutaçãoRESUMO
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive disease caused by thymidine phosphorylase (TP) enzyme defect. As gastrointestinal changes do not revert in patients undergone TP replacement therapy, one can postulate that other unexplored mechanisms contribute to MNGIE pathophysiology. Hence, we focused on the local TP angiogenic potential that has never been considered in MNGIE. In this study, we investigated the enteric submucosal microvasculature and the effect of hypoxia on fibrosis and enteric neurons density in jejunal full-thickness biopsies collected from patients with MNGIE. Orcein staining was used to count blood vessels based on their size. Fibrosis was assessed using the Sirius Red and Fast Green method. Hypoxia and neoangiogenesis were determined via hypoxia-inducible-factor-1α (HIF-1α) and vascular endothelial cell growth factor (VEGF) protein expression, respectively. Neuron-specific enolase was used to label enteric neurons. Compared with controls, patients with MNGIE showed a decreased area of vascular tissue, but a twofold increase of submucosal vessels/mm2 with increased small size and decreased medium and large size vessels. VEGF positive vessels, fibrosis index, and HIF-1α protein expression were increased, whereas there was a diminished thickness of the longitudinal muscle layer with an increased interganglionic distance and reduced number of myenteric neurons. We demonstrated the occurrence of an angiopathy in the GI tract of patients with MNGIE. Neoangiogenetic changes, as detected by the abundance of small size vessels in the jejunal submucosa, along with hypoxia provide a morphological basis to explain neuromuscular alterations, vasculature breakdown, and ischemic abnormalities in MNGIE.NEW & NOTEWORTHY Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is characterized by a genetically driven defect of thymidine phosphorylase, a multitask enzyme playing a role also in angiogenesis. Indeed, major gastrointestinal bleedings are life-threatening complications of MNGIE. Thus, we focused on jejunal submucosal vasculature and showed intestinal microangiopathy as a novel feature occurring in this disease. Notably, vascular changes were associated with neuromuscular abnormalities, which may explain gut dysfunction and help to develop future therapeutic approaches in MNGIE.
Assuntos
Trato Gastrointestinal/metabolismo , Pseudo-Obstrução Intestinal/metabolismo , Encefalomiopatias Mitocondriais/metabolismo , Distrofia Muscular Oculofaríngea/metabolismo , Neovascularização Patológica/metabolismo , Oftalmoplegia/congênito , Trato Gastrointestinal/patologia , Humanos , Pseudo-Obstrução Intestinal/patologia , Encefalomiopatias Mitocondriais/patologia , Distrofia Muscular Oculofaríngea/patologia , Neovascularização Patológica/patologia , Oftalmoplegia/metabolismo , Oftalmoplegia/patologia , Timidina Fosforilase/metabolismoRESUMO
Smooth Muscle Cells (SMC) are unique amongst all muscle cells in their capacity to modulate their phenotype. Indeed, SMCs do not terminally differentiate but instead harbour a remarkable capacity to dedifferentiate, switching between a quiescent contractile state and a highly proliferative and migratory phenotype, a quality often associated to SMC dysfunction. However, phenotypic plasticity remains poorly examined in the field of gastroenterology in particular in pathologies in which gut motor activity is impaired. Here, we assessed SMC status in biopsies of infants with chronic intestinal pseudo-obstruction (CIPO) syndrome, a life-threatening intestinal motility disorder. We showed that CIPO-SMCs harbour a decreased level of contractile markers. This phenotype is accompanied by an increase in Platelet-Derived Growth Factor Receptor-alpha (PDGFRA) expression. We showed that this modulation occurs without origin-related differences in CIPO circular and longitudinal-derived SMCs. As we characterized PDGFRA as a marker of digestive mesenchymal progenitors during embryogenesis, our results suggest a phenotypic switch of the CIPO-SMC towards an undifferentiated stage. The development of CIPO-SMC culture and the characterization of SMC phenotypic switch should enable us to design therapeutic approaches to promote SMC differentiation in CIPO.