sirolimus and Deafness

Mitochondrial diseases represent a significant clinical challenge. Substantial efforts have been devoted to identifying therapeutic strategies for mitochondrial disorders, but effective interventions have remained elusive. Recently, we reported attenuation of disease in a mouse model of the human mitochondrial disease Leigh syndrome through pharmacological inhibition of the mechanistic target of rapamycin (mTOR). The human mitochondrial disorder MELAS/MIDD (Mitochondrial Encephalopathy with Lactic Acidosis and Stroke-like Episodes/Maternally Inherited Diabetes and Deafness) shares many phenotypic characteristics with Leigh syndrome. MELAS/MIDD often leads to organ failure and transplantation and there are currently no effective treatments. To examine the therapeutic potential of mTOR inhibition in human mitochondrial disease, four kidney transplant recipients with MELAS/MIDD were switched from calcineurin inhibitors to mTOR inhibitors for immunosuppression. Primary fibroblast lines were generated from patient dermal biopsies and the impact of rapamycin was studied using cell-based end points. Metabolomic profiles of the four patients were obtained before and after the switch. pS6, a measure of mTOR signaling, was significantly increased in MELAS/MIDD cells compared to controls in the absence of treatment, demonstrating mTOR overactivation. Rapamycin rescued multiple deficits in cultured cells including mitochondrial morphology, mitochondrial membrane potential, and replicative capacity. Clinical measures of health and mitochondrial disease progression were improved in all four patients following the switch to an mTOR inhibitor. Metabolomic analysis was consistent with mitochondrial function improvement in all patients.

Topics: Adult; Allografts; Animals; Calcineurin Inhibitors; Cells, Cultured; Deafness; Diabetes Mellitus, Type 2; Disease Progression; Female; Graft Rejection; Humans; Immunosuppressive Agents; Kidney; Kidney Failure, Chronic; Kidney Transplantation; Male; MELAS Syndrome; Membrane Potential, Mitochondrial; Mice; Middle Aged; Mitochondria; Mitochondrial Diseases; Primary Cell Culture; Sirolimus; TOR Serine-Threonine Kinases; Treatment Outcome

Little is known about hearing impairment in patients after organ transplantation. Few cases of hearing loss associated with different immunosuppressants have been published. To evaluate severe hearing impairment in patients after liver transplantation (OLT), all living adult patients in need of a hearing aid were analyzed. Out of 521 transplanted patients, 25 (5%) were identified with hearing aids. Nine (36%) of these patients either suffered from hearing loss prior to OLT or experienced risk factors such as ototoxic drugs. Of the remaining 16 patients who developed severe hearing loss after OLT (64%), half were men. Mean age was 42 +/- 18 years at OLT, which took place 8 +/- 4 years ago. Main transplantation indication was virus-induced cirrhosis (44%). In 14/16 (88%) patients, the hearing aid was bilateral. In 50% of patients, the hearing aid was necessary within 2 years post-OLT. Additional tinnitus was present in 9/16 patients (56%), otalgia in three patients (19%). Four patients (25%) reported a history of sudden deafness. In three of them, an association with high levels of calcineurin inhibitors was found. The proportion of patients receiving tacrolimus (50%) was relatively higher than those receiving cyclosporine (50%) compared to control patients (28% respectively 64%, P < .05). In conclusion, a high incidence of severe hearing loss was found in patients after liver transplantation. In most patients, onset of hearing loss is early and bilateral, suggesting a dose-dependent toxicity. The pathogenetic role of different immunosuppressants remains to be evaluated.

Topics: Adult; Calcineurin Inhibitors; Deafness; Follow-Up Studies; Hearing Aids; Hearing Loss; Humans; Immunosuppressive Agents; Liver Cirrhosis; Liver Transplantation; Postoperative Complications; Retrospective Studies; Sirolimus; Surveys and Questionnaires; Tacrolimus; Time Factors