title: Liver as a source for thymidine phosphorylase replacement in mitochondrial neurogastrointestinal encephalomyopathy.
abstract: Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare autosomal recessive mitochondrial disease associated with mutations in the nuclear TYMP gene. As a result, the thymidine phosphorylase (TP) enzyme activity is markedly reduced leading to toxic accumulation of thymidine and therefore altered mitochondrial DNA. MNGIE is characterized by severe gastrointestinal dysmotility, neurological impairment, reduced life expectancy and poor quality of life. There are limited therapeutic options for MNGIE. In the attempt to restore TP activity, allogenic hematopoietic stem cell transplantation has been used as cellular source of TP. The results of this approach on ∼ 20 MNGIE patients showed gastrointestinal and neurological improvement, although the 5-year mortality rate is about 70%. In this study we tested whether the liver may serve as an alternative source of TP. We investigated 11 patients (7M; 35-55 years) who underwent hepatic resection for focal disorders. Margins of normal liver tissue were processed to identify, quantify and localize the TP protein by Western Blot, ELISA, and immunohistochemistry, and to evaluate TYMP mRNA expression by qPCR. Western Blot identified TP in liver with a TP/GAPDH ratio of 0.9 ± 0.5. ELISA estimated TP content as 0.5 ± 0.07 ng/μg of total protein. TP was identified in both nuclei and cytoplasm of hepatocytes and sinusoidal lining cells. Finally, TYMP mRNA was expressed in the liver. Overall, our study demonstrates that the liver is an important source of TP. Orthotopic liver transplantation may be considered as a therapeutic alternative for MNGIE patients.
authors.affiliation: Department of Surgical and Medical Sciences, University of Bologna, Bologna, Italy; Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Boschetti
authors.affiliation: Institute of Neurological Sciences, University of Bologna, Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: D'Alessandro
authors.affiliation: Department of Surgical and Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Bianco
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Valerio
authors.initials: V
authors.lastname: Carelli
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Cenacchi
authors.affiliation: Department of Surgical and Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Antonio D
authors.initials: AD
authors.lastname: Pinna
authors.affiliation: Department of Surgical and Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Del Gaudio
authors.affiliation: Neurology Unit, St. Orsola-Malpighi Hospital, Bologna, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Rinaldi
authors.affiliation: Department of Surgical and Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Stanghellini
authors.affiliation: Department of Surgical and Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Loris
authors.initials: L
authors.lastname: Pironi
authors.affiliation: Department of Surgical and Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Kerry
authors.initials: K
authors.lastname: Rhoden
authors.affiliation: Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy.
authors.forename: Vitaliano
authors.initials: V
authors.lastname: Tugnoli
authors.affiliation: Department of Medico-Surgical Sciences and Biotechnologies, University 'La Sapienza', Rome, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Casali
authors.affiliation: Department of Surgical and Medical Sciences, University of Bologna, Bologna, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: De Giorgio
mesh_terms: D000328:Adult; D015153:Blotting, Western; D004386:Duodenum / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008099:Liver / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D017237:Mitochondrial Encephalomyopathies / Q000235:genetics / Q000473:pathology*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D013939:Thymidine Phosphorylase / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D013939:Thymidine Phosphorylase