Targeting the dysregulated mammalian target of rapamycin pathway in organ transplantation: killing 2 birds with 1 stone. Transplant Rev (Orlando). 2011;25:145-153. [PMID: 21419611 DOI: 10.1016/j.trre.2010.11.001]

Living Donor Preemptive Kidney Transplantation in Tuberous Sclerosis Complex Patient and the Role of Mammalian Target of Rapamycin Inhibitor: A Case Report

BACKGROUND

Kidney transplantation (KT) is the preferred treatment for end-stage kidney disease (ESKD), while preemptive (PE) living donor (LD) KT is associated with better survival, quality of life, and lower costs. Tuberous sclerosis complex (TSC) is a genetic multisystem disorder. Renal involvement (multiple bilateral angiomyolipoma [AMLs], cysts, renal cell carcinoma [RCC]) is related to significant morbidity, including ESKD and KT. Nephrectomy in TSC patients before KT is controversial. Affected kidneys carry a risk of hemorrhage or malignancy, while AMLs may be fat-poor and are often hardly distinguishable from RCC in magnetic resonance (MR)/computed tomography. On the other hand nephrectomy impedes PE KT. Mammalian target of rapamycin inhibitors (mTORi) have proved efficacy in many TSC complications, including AMLs, fat-poor AMLs, TSC-related RCC, and immunosuppressive (IS) treatment.

CASE REPORT

A 29-year-old female TSC patient was referred for evaluation to the TSC reference center. Her family history was negative for TSC. A clinical evaluation revealed multisystem TSC manifestation (skin, brain, lungs, kidneys). MR disclosed indeterminate fat-poor renal lesions, possibly AMLs, but RCC could not be excluded. A comparison with previous MR did not show any significant progression. Due to ESKD, the patient was qualified for PE LD (mother) KT. mTORi, sirolimus, was used in IS. Creatinine at discharge was 2.1 mg/dL. Sixteen months later, MR showed significant reduction in tumor size. Two years after KT, graft function remained stable (creatinine 1.98 mg/dL). No complications related to renal lesions occurred.

CONCLUSIONS

mTORi are the therapy of choice in TSC patients after KT, achieving IS effect and improvement in TSC manifestations while avoiding nephrectomy and management of patients with indeterminate renal lesions, especially in the case of PE KT.

Efficacy and Safety of Mammalian Target of Rapamycin Inhibitor Use-Long-term Follow-up of First Tuberous Sclerosis Complex Patient Treated De Novo With Sirolimus After Kidney Transplantation: A Case Report

Mammalian target of rapamycin inhibitors (mTORI) are increasingly used in the treatment of tuberous sclerosis complex (TSC) and as immunosuppressants after organ transplantation. In TSC patients, mTORI are the treatment of choice after kidney transplantation. It is still under debate if benefits from long-term mTORI use will not be limited by side effects.

MATERIALS AND METHODS

We report long-term follow-up data of the first TSC patient after kidney transplantation treated with sirolimus de novo. In 2005, a female patient was transplanted with a kidney graft after bilateral nephrectomy due to angiomyolipoma. Initial immunosuppressive treatment consisted of antithymocyte globulin, methylprednisolone, tacrolimus, and, due to TSC diagnosis, sirolimus. Creatinine level at discharge was 1.2 mg/dL.

RESULTS

Long-term mTORI use resulted in skin lesion regression (angiofibromas, "confetti" skin lesions, shagreen patch) and disease stabilization in brain, abdominal, and chest magnetic resonance imaging/computed tomography scans. Pulmonary function tests showed improvement in restriction and slow deterioration in obstruction and diffusion parameters. Sirolimus related adverse reactions were hyperlipidemia and hypertriglyceridemia and respiratory and urinary tract infections. No gastrointestinal or hematologic symptoms occurred. Sirolimus concentrations ranged between 1.7 and 8.2 ng/mL (mean 4.01 ± 2.09 ng/mL). Since 2009 proteinuria and slow increase in creatinine level have been observed. No biopsy was performed to establish etiology and potential association with mTORI. In 2017 creatinine level was 2.2 mg/dL.

CONCLUSION

The case of the patient confirms clinical effectiveness and acceptable safety of long-term mTORI treatment. Long-term mTORI use requires meticulous patient observation to optimize dosage, achieve immunosuppressive effect, and improve TSC manifestations with minimal side effects.

The role of mechanistic target of rapamycin (mTOR) complexes signaling in the immune responses

The mechanistic Target of Rapamycin (mTOR) is an evolutionarily conserved serine/threonine kinase which is a member of the PI3K related kinase (PIKK) family. mTOR emerged as a central node in cellular metabolism, cell growth, and differentiation, as well as cancer metabolism. mTOR senses the nutrients, energy, insulin, growth factors, and environmental cues and transmits signals to downstream targets to effectuate the cellular and metabolic response. Recently, mTOR was also implicated in the regulation of both the innate and adaptive immune responses. This paper will summarize the current knowledge of mTOR, as related to the immune microenvironment and immune responses.

Colonoscopic electrosurgical resection of high-risk polyps: Pretreatment methods

AIM: To discuss the pretreatment techniques and methods for colonoscopic electrosurgical resection of high-risk polyps.

METHODS: This study comprised 131 patients, who had a total of 145 high-risk colorectal polyps, including wide-pedicle polyps, large polyps, and those with a hyperemic surface, obvious blood vessels through the base, or poor endoscopic exposure). For wide-pedicle polyps (pedicle diameter > 1 cm), nylon snare ligation was performed before electrosurgical resection. For large pedunculated polyps (>2 cm, pedicle diameter < 1 cm), titanium clipping was performed before electrosurgical resection. For 2.0-3.0 cm wide-base/Artie polyps, fully lifting of polyps was achieved by basal submucosal injection of liquid before the resection of polyps. For polyps with a hyperemic surface, obvious blood vessels through the base, or poor endoscopic exposure, trial colonoscopic resection was initially performed. If the resection was difficult, immediate laparoscopic treatment was given. Intestinal bleeding, intestinal perforation and other complications were recorded.

RESULTS: Nylon snare ligation was performed in 10 polyps, metal titanium clamping in 32 polyps, basal submucosal injection in 60 polyps, colonoscopic resection in 31 polyps, and laparoscopic resection in 12 polyps. No intestinal bleeding, intestinal perforation or other severe complications occurred.

CONCLUSION: Effective pretreatment can improve the management of high-risk intestinal polyps, and endoscopic treatment can improve the safety of treatment and avoid the occurrence of intestinal bleeding, intestinal perforation and other complications.

mTOR signaling pathway and Peutz-Jeghers syndrome

The mammalian target of rapamycin (mTOR) signaling pathway is one of the most important intracellular signal transduction pathways and is involved in a series of biological activities, such as gene transcription, protein translation, ribosome synthesis, and cell apoptosis. The abnormal activation of the mTOR signaling pathway has a close relationship with the development of some hereditary diseases, tumors and diabetes. Intervention with biological processes of these diseases by influencing the mTOR signalling pathway with all kinds of biological means has become a hot area of research for several years. This article reviews the recent advances in understanding the composition and function of the mTOR signaling pathway and its role in the pathogenesis of Peutz-Jeghers syndrome. It is expected that molecular therapy targeting the mTOR signalling pathway can be used for preventive therapy of Peutz-Jeghers syndrome.

Advances in the prevention, diagnosis and treatment of Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is an autosomal dominant inherited disease caused by inactivating germline mutations of the LKB1/STK11 gene and characterized by mucocutaneous pigmentation, multiple gastrointestinal hamartomatous polyps and family history. Life-threatening complications include intestinal obstruction and an increased risk for developing gastrointestinal malignancies and extraintestinal cancers. Surgery and endoscopic therapy are still main ways to manage gastrointestinal polyposis in PJS patients, and double-balloon enteroscopy has important clinical significance in the diagnosis and treatment of this disease. With the development of translational medicine, molecular targeted therapy (e.g., selective COX-2 inhibitors) brings a new approach to preventive treatment of gastrointestinal polyposis in PJS patients. Traditional Chinese medicine provides an alternative choice. In this paper, we review the recent advances in the prevention, diagnosis and treatment of PJS.