Paola Tomei

Systemic and Nonrenal Adverse Effects Occurring in Renal Transplant Patients Treated with mTOR Inhibitors

The mammalian target of rapamycin inhibitors (mTOR-I), sirolimus and everolimus, are immunosuppressive drugs largely used in renal transplantation. The main mechanism of action of these drugs is the inhibition of the mammalian target of rapamycin (mTOR), a regulatory protein kinase involved in lymphocyte proliferation. Additionally, the inhibition of the crosstalk among mTORC1, mTORC2, and PI3K confers the antineoplastic activities of these drugs. Because of their specific pharmacological characteristics and their relative lack of nephrotoxicity, these inhibitors are valid option to calcineurine inhibitors (CNIs) for maintenance immunosuppression in renal transplant recipients with chronic allograft nephropathy. However, as other immunosuppressive drugs, mTOR-I may induce the development of several adverse effects that need to be early recognized and treated to avoid severe illness in renal transplant patients. In particular, mTOR-I may induce systemic nonnephrological side effects including pulmonary toxicity, hematological disorders, dysmetabolism, lymphedema, stomatitis, cutaneous adverse effects, and fertility/gonadic toxicity. Although most of the adverse effects are dose related, it is extremely important for clinicians to early recognize them in order to reduce dosage or discontinue mTOR-I treatment avoiding the onset and development of severe clinical complications.

Mitochondria: a new therapeutic target in chronic kidney disease.

Cellular metabolic changes during chronic kidney disease (CKD) may induce higher production of oxygen radicals that play a significant role in the progression of renal damage and in the onset of important comorbidities. This condition seems to be in part related to dysfunctional mitochondria that cause an increased electron “leakage” from the respiratory chain during oxidative phosphorylation with a consequent generation of reactive oxygen species (ROS).ROS are highly active molecules that may oxidize proteins, lipids and nucleic acids with a consequent damage of cells and tissues.To mitigate this mitochondria-related functional impairment, a variety of agents (including endogenous and food derived antioxidants, natural plants extracts, mitochondria-targeted molecules) combined with conventional therapies could be employed.However, although the anti-oxidant properties of these substances are well known, their use in clinical practice has been only partially investigated. Additionally, for their correct utilization is extremely important to understand their effects, to identify the correct target of intervention and to minimize adverse effects.Therefore, in this manuscript, we reviewed the characteristics of the available mitochondria-targeted anti-oxidant compounds that could be employed routinely in our nephrology, internal medicine and renal transplant centers. Nevertheless, large clinical trials are needed to provide more definitive information about their use and to assess their overall efficacy or toxicity.

Monoclonal antibody therapy and renal transplantation: focus on adverse effects.

A series of monoclonal antibodies (mAbs) are commonly utilized in renal transplantation as induction therapy (a period of intense immunosuppression immediately before and following the implant of the allograft), to treat steroid-resistant acute rejections, to decrease the incidence and mitigate effects of delayed graft function, and to allow immunosuppressive minimization. Additionally, in the last few years, their use has been proposed for the treatment of chronic antibody-mediated rejection, a major cause of late renal allograft loss. Although the exact mechanism of immunosuppression and allograft tolerance with any of the currently used induction agents is not completely defined, the majority of these medications are targeted against specific CD proteins on the T or B cells surface (e.g., CD3, CD25, CD52). Moreover, some of them have different mechanisms of action. In particular, eculizumab, interrupting the complement pathway, is a new promising treatment tool for acute graft complications and for post-transplant hemolytic uremic syndrome. While it is clear their utility in renal transplantation, it is also unquestionable that by using these highly potent immunosuppressive agents, the body loses much of its innate ability to mount an adequate immune response, thereby increasing the risk of severe adverse effects (e.g., infections, malignancies, haematological complications). Therefore, it is extremely important for clinicians involved in renal transplantation to know the potential side effects of monoclonal antibodies in order to plan a correct therapeutic strategy minimizing/avoiding the onset and development of severe clinical complications.

mTOR inhibitors and renal allograft: Yin and Yang.

Mammalian target of rapamycin inhibitors (mTOR-I), everolimus and sirolimus, are immunosuppressive drugs extensively used in renal transplantation. Their main mechanism of action is the inhibition of cell signaling through the PI3 K/Akt/mTOR pathway. This interesting mechanism of action confers to these medications both great immunosuppressive potential and important anti-neoplastic properties. Although the clinical utility of this drug category, as with other antineoplastic/immunosuppressants, is clear, the use of mTOR-I commonly results in the development of several complications. In particular, these agents may determine severe renal toxicity that, as recent studies report, seems clearly correlated to dose and duration of drug use. The mTOR-I-induced renal allograft spectrum of toxicity includes the enhanced incidence of delayed graft function, nephrotoxicity in particular when co-administered with calcineurin inhibitors (CNI) and onset of proteinuria. The latter effect appears highly frequent in patients undergoing mTOR-I treatment and significantly associated with a rapid graft lost. The damage leading to this complication interests both the glomerular and tubular area. mTOR-I cause an inhibition of proliferation in podocytes and the epithelial-to-mesenchymal transition in tubular cells. Interestingly, all these side effects are mostly reversible and dose related. Therefore, it is unquestionable that these particular drugs should be administered at the lowest dose able to maintain relatively low trough levels, in order to maximize their important and specific therapeutic effects while minimizing or avoiding drug toxicities. Utilization of low dosages of mTOR-I should be encouraged not only in CNI-combined schemas, but also when administered alone in a CNI-free immunosuppressive protocol.

Personalization of the Immunosuppressive Treatment in Renal Transplant Recipients: The Great Challenge in “Omics” Medicine

Renal transplantation represents the most favorable treatment for patients with advanced renal failure and it is followed, in most cases, by a significant enhancement in patients’ quality of life. Significant improvements in one-year renal allograft and patients’ survival rates have been achieved over the last 10 years primarily as a result of newer immunosuppressive regimens. Despite these notable achievements in the short-term outcome, long-term graft function and survival rates remain less than optimal. Death with a functioning graft and chronic allograft dysfunction result in an annual rate of 3%–5%. In this context, drug toxicity and long-term chronic adverse effects of immunosuppressive medications have a pivotal role. Unfortunately, at the moment, except for the evaluation of trough drug levels, no clinically useful tools are available to correctly manage immunosuppressive therapy. The proper use of these drugs could potentiate therapeutic effects minimizing adverse drug reactions. For this purpose, in the future, “omics” techniques could represent powerful tools that may be employed in clinical practice to routinely aid the personalization of drug treatment according to each patient’s genetic makeup. However, it is unquestionable that additional studies and technological advances are needed to standardize and simplify these methodologies.

Sclerostin and Dickkopf-1 in Post-menopausal Renal Allograft Recipients

BACKGROUND Age, pre-existing renal osteodistrophy, impaired renal function, and chronic use of immunosuppressive drugs are the main factors involved in the onset and development of bone metabolism disturbances and skeletal alterations occurring after renal transplantation. However, at the state of the art, no reports have analyzed the additional post-menopausal physiological mechanisms associated with the onset and development of bone complications in renal transplant recipients. METHODS We measured by means of molecular strategies (enzyme-linked immunoassay, chemiluminescence) the serum levels of Sclerostin and Dickkopf-1 (DKK1), two major antagonists of the Wnt/β-catenin pathway, and several bone resorption/formation biomarkers (N-terminal procollagen type 1, bone-specific alkaline phosphatase, and serum C-terminal telopeptides of type I collagen) in 19 post-menopausal kidney transplant patients and 12 post-menopausal chronic kidney disease patients (CKD group) matched for age and renal function. RESULTS Our results showed that the levels of both Wnt antagonists were similar in the two study groups (P=.15 and .96, respectively). Additionally, no correlation was found between Sclerostin and DKK1 serum levels in all patients included in the study (R2=0.03, P=.2). After statistical analysis, we found no differences in the bone resorption/formation biomarkers between renal transplant and CKD patients. Multivariate analysis showed that Sclerostin levels were significantly positively correlated with serum phosphorus levels (P=.008) and inversely correlated with renal function (P=.026). Surprisingly, no significant correlation was found between all the analyzed demographic and clinical parameters and DKK1. CONCLUSIONS Our study demonstrated for the first time that renal transplantation per se and immunosuppressive treatments do not represent additional factors contributing to bone metabolic/biochemical alterations in post-menopausal women. However, our results emphasized that a better preservation of the graft function could significantly slow down the progression of bone metabolic deregulations and prevent clinical bone complications.

Unusual renal presentation of Fabry disease in a female patient.

Background. A 29-year-old white woman with a family history of Fabry disease was referred to a nephrology clinic with hypertension and nephropathy. Her renal function was below normal (serum creatinine level 141 µmol/l; estimated glomerular filtration rate 41 ml/min/1.73 m2) with no proteinuria or albuminuria.Investigations. Medical history, physical examination, leukocyte α-galactosidase A assay, laboratory tests (for antinuclear antibodies, antineutrophil cytoplasmic antibodies, lupus anticoagulant, anticardiolipin antibodies, complement and cryoglobulin), ophthalmological examination, echocardiography, brain magnetic resonance angiography, renal ultrasonography, renal color echo-Doppler scan, renal magnetic resonance angiography, renal angiography and renal biopsy.Diagnosis. Diffuse sclero-atrophic renal tissue changes and widespread renal arterio-arteriolosclerotic changes secondary to Fabry disease.Treatment. Angiotensin-converting-enzyme inhibitors and maintenance treatment with agalsidase-β, 1 mg/kg body weight, every 2 weeks.

Tremor induced by Calcineurin inhibitor immunosuppression: a single-centre observational study in kidney transplanted patients

IntroductionTremor is the most frequent and disabling neurological side effect under Calcineurin inhibitor-induced immunosuppression, but no studies have defined its phenomenology, severity, distribution, the impact on quality of life, as well as of other neurological symptoms associated.Methods126 consecutive kidney-transplanted patients, under treatment with Cyclosporin A, Tacrolimus and non-Calcineurin inhibitors, within therapeutic range, were enrolled. Participants underwent a deep neurological examination by two blinded to the treatment raters, and a blood sampling to assess plasmatic immunosuppressant level and nephrological function tests. Tremor and cerebellar signs were scored according to the Fahn–Tolosa–Marin and the SARA scale. Parkinsonism was excluded applying the UPDRS (part III).ResultsTremor was more common and severe in the Tacrolimus group, similar to impairment in ADL. Regardless of treatment, tremor involved both upper and lower limbs and was activated by action, but in about 50% of cases presented in action and rest condition. Plasmatic level of Tacrolimus was higher in patients with tremor than in those without, while cholesterol was significantly lower. Cerebellar and neuropathic signs were overall mild and were not significantly different across the three groups comparing patients with and without tremor.ConclusionsNon-Calcineurin inhibitors such as Sirolimus have the lowest propensity to induce tremor and with a milder severity, while Calcineurin inhibitors, especially Tacrolimus, the highest, and regardless of the formulation. Plasmatic concentration of Tacrolimus was higher in tremulous patients; further research needs to validate the role of cholesterol plasmatic concentration in predicting the occurrence of tremor in patients on Tacrolimus.

In Vitro Identification of New Transcriptomic and miRNomic Profiles Associated with Pulmonary Fibrosis Induced by High Doses Everolimus: Looking for New Pathogenetic Markers and Therapeutic Targets

The administration of Everolimus (EVE), a mTOR inhibitor used in transplantation and cancer, is often associated with adverse effects including pulmonary fibrosis. Although the underlying mechanism is not fully clarified, this condition could be in part caused by epithelial to mesenchymal transition (EMT) of airway cells. To improve our knowledge, primary bronchial epithelial cells (BE63/3) were treated with EVE (5 and 100 nM) for 24 h. EMT markers (α-SMA, vimentin, fibronectin) were measured by RT-PCR. Transepithelial resistance was measured by Millicell-ERS ohmmeter. mRNA and microRNA profiling were performed by Illumina and Agilent kit, respectively. Only high dose EVE increased EMT markers and reduced the transepithelial resistance of BE63/3. Bioinformatics showed 125 de-regulated genes that, according to enrichment analysis, were implicated in collagen synthesis/metabolism. Connective tissue growth factor (CTGF) was one of the higher up-regulated mRNA. Five nM EVE was ineffective on the pro-fibrotic machinery. Additionally, 3 miRNAs resulted hyper-expressed after 100 nM EVE and able to regulate 31 of the genes selected by the transcriptomic analysis (including CTGF). RT-PCR and western blot for MMP12 and CTGF validated high-throughput results. Our results revealed a complex biological network implicated in EVE-related pulmonary fibrosis and underlined new potential disease biomarkers and therapeutic targets.

Everolimus-associated interstitial pneumonia in a renal transplant patient: a case report

The mTOR inhibitors (mTORi, mammalian target of rapamycin; sirolimus and everolimus) have been recently introduced in clinical practice to improve the therapeutic strategies for maintenance of organ transplant and to slow down the progression of chronic renal failure, thanks to their good immunosuppressive properties and absence of renal toxicity. Additionally, mTORi have some antineoplastic and cardioprotective effects. At the same time, mTORi have several collateral effects, often dose dependent and generally reversible after cessation or minimization of the drug dosage. In particular, in the last years, sirolimus-associated pulmonary toxicity has been reported. We describe a clinical case of a young woman with a renal transplant, followed at our Renal Transplant Center, hospitalized for fever and cough unresponsive to antibiotic therapy that, at the time of admission in our renal unit, showed a chest CT scan diagnosis compatible with a drug-related organizing pneumonia or interstitial infiltrates (BOOP). Based on the above diagnosis, we decided to significantly reduce the mTORi dosage reaching stable trough level of 2.5–3 ug/L. After few days, we assisted at an improvement of the clinical status, defervescence and reduction of the pulmonary symptoms. Besides, the microbiological and neoplastic laboratory tests performed on bronchial washing were negative. At day 15, a new chest CT showed a significant reduction of multiple parenchyma areas of thickening. After 3 months, the medical conditions have improved with stable renal function. Our case report describes an everolimus-related “lung syndrome” successfully treated with a significant minimization of mTORi dosage. Our experience may be useful to help clinicians treating mTORi-related pulmonary complications.