RESUMEN
Dysfunction of cellular homeostasis can lead to misfolding of proteins thus acquiring conformations prone to polymerization into pathological aggregates. This process is associated with several disorders, including neurodegenerative diseases, such as Parkinson's disease (PD), and endoplasmic reticulum storage disorders (ERSDs), like alpha-1-antitrypsin deficiency (AATD) and hereditary hypofibrinogenemia with hepatic storage (HHHS). Given the shared pathophysiological mechanisms involved in such conditions, it is necessary to deepen our understanding of the basic principles of misfolding and aggregation akin to these diseases which, although heterogeneous in symptomatology, present similarities that could lead to potential mutual treatments. Here, we review: (i) the pathological bases leading to misfolding and aggregation of proteins involved in PD, AATD, and HHHS: alpha-synuclein, alpha-1-antitrypsin, and fibrinogen, respectively, (ii) the evidence linking each protein aggregation to the stress mechanisms occurring in the endoplasmic reticulum (ER) of each pathology, (iii) a comparison of the mechanisms related to dysfunction of proteostasis and regulation of homeostasis between the diseases (such as the unfolded protein response and/or autophagy), (iv) and clinical perspectives regarding possible common treatments focused on improving the defensive responses to protein aggregation for diseases as different as PD, and ERSDs.
Asunto(s)
Afibrinogenemia/genética , Fibrinógeno/química , Enfermedad de Parkinson/genética , Deficiencia de alfa 1-Antitripsina/genética , alfa 1-Antitripsina/química , alfa-Sinucleína/química , Afibrinogenemia/tratamiento farmacológico , Afibrinogenemia/metabolismo , Afibrinogenemia/patología , Animales , Autofagia/efectos de los fármacos , Autofagia/genética , Coagulantes/uso terapéutico , Retículo Endoplásmico/efectos de los fármacos , Retículo Endoplásmico/metabolismo , Retículo Endoplásmico/patología , Fibrinógeno/genética , Fibrinógeno/metabolismo , Regulación de la Expresión Génica , Humanos , Hígado/metabolismo , Hígado/patología , Fármacos Neuroprotectores/uso terapéutico , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/patología , Inhibidores de Proteasas/uso terapéutico , Agregado de Proteínas/efectos de los fármacos , Pliegue de Proteína/efectos de los fármacos , Respuesta de Proteína Desplegada/efectos de los fármacos , alfa 1-Antitripsina/genética , alfa 1-Antitripsina/metabolismo , Deficiencia de alfa 1-Antitripsina/tratamiento farmacológico , Deficiencia de alfa 1-Antitripsina/metabolismo , Deficiencia de alfa 1-Antitripsina/patología , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismoRESUMEN
Over a 15-yr period of observation, among the 205 children who underwent liver transplantations, one of them developed a particular type of late graft dysfunction with clinical and histological similarity to autoimmune hepatitis. The patient had alpha1-antitrypsin deficiency and did not previously have autoimmune hepatitis or any other autoimmune disease before transplantation. Infectious and surgical complications were excluded. After repeated episodes of unexplained fluctuations of liver function tests and liver biopsies demonstrating reactive or a biliary pattern, without any corresponding alteration of percutaneous cholangiography, a liver-biopsy sample taken 4 yr after the transplant showed active chronic hepatitis progressing to cirrhosis, portal lymphocyte aggregates, and a large number of plasma cells. At that time, autoantibodies (gastric parietal cell antibody, liver-kidney microsomal antibody, and anti-hepatic cytosol) were positive and serum IgG levels were high. Based on these findings of autoimmune disease, a diagnosis of 'de novo autoimmune hepatitis' was made. The treatment consisted of reducing the dose of cyclosporine, reintroduction of corticosteroids, and addition of mycophenolate mofetil. After 19 months of treatment, a new liver-biopsy sample showed marked reduction of portal and lobular inflammatory infiltrate, with regression of fibrosis and of the architectural disruption. At that time, serum autoantibodies became negative. The last liver-biopsy sample showed inactive cirrhosis and disappearance of interface hepatitis and of plasma cell infiltrate. Presently, 9 yr after the transplantation, the patient is doing well, with normal liver function tests and no evidence of cirrhosis. Her immunosuppressive therapy consists of tacrolimus, mycophenolate mofetil, and prednisolone. In conclusion, the present case demonstrates that de novo autoimmune hepatitis can appear in liver-transplant patients despite appropriate anti-rejection immunosuppression, and triple therapy with tacrolimus, mycophenolate mofetil, and prednisolone could sustain the graft and prevent retransplantation.