Therapeutic role of sirolimus in non-transplant kidney disease

Prevention of neointimal hyperplasia after coronary artery bypass graft via local delivery of sirolimus and rosuvastatin: network pharmacology and in vivo validation

BACKGROUND

Coronary artery bypass graft (CABG) is generally used to treat complex coronary artery disease. Treatment success is affected by neointimal hyperplasia (NIH) of graft and anastomotic sites. Although sirolimus and rosuvastatin individually inhibit NIH progression, the efficacy of combination treatment remains unknown.

METHODS

We identified cross-targets associated with CABG, sirolimus, and rosuvastatin by using databases including DisGeNET and GeneCards. GO and KEGG pathway enrichment analyses were conducted using R studio, and target proteins were mapped in PPI networks using Metascape and Cytoscape. For in vivo validation, we established a balloon-injured rabbit model by inducing NIH and applied a localized perivascular drug delivery device containing sirolimus and rosuvastatin. The outcomes were evaluated at 1, 2, and 4 weeks post-surgery.

RESULTS

We identified 115 shared targets between sirolimus and CABG among databases, 23 between rosuvastatin and CABG, and 96 among all three. TNF, AKT1, and MMP9 were identified as shared targets. Network pharmacology predicted the stages of NIH progression and the corresponding signaling pathways linked to sirolimus (acute stage, IL6/STAT3 signaling) and rosuvastatin (chronic stage, Akt/MMP9 signaling). In vivo experiments demonstrated that the combination of sirolimus and rosuvastatin significantly suppressed NIH progression. This combination treatment also markedly decreased the expression of inflammation and Akt signaling pathway-related proteins, which was consistent with the predictions from network pharmacology analysis.

CONCLUSIONS

Sirolimus and rosuvastatin inhibited pro-inflammatory cytokine production during the acute stage and regulated Akt/mTOR/NF-κB/STAT3 signaling in the chronic stage of NIH progression. These potential synergistic mechanisms may optimize treatment strategies to improve long-term patency after CABG.

Bioproperties, Nanostructured System and Analytical and Bioanalytical Methods for Determination of Rapamycin: A Review

The drug rapamycin is a potent inhibitor of the mTOR complex, acting directly in the signaling cascade of this protein complex; interrupting cell proliferation, in addition to being an extremely efficient immunosuppressant. Currently this drug is being used in several types of cancer. Rapamycin has been a target of great interest within nanomedicine involving nanostructured systems for drug delivery aiming to increase the bioactivity and bioavailability of this drug. In addition, there is a constant search for analytical methods to identify and quantify this drug. Numerous high-performance liquid chromatography analytical techniques, mass spectrometry and immunoassay techniques have been employed efficiently in an attempt to develop increasingly sensitive analytical methods. Thus, this review sought to bring together current and relevant scientific works involving rapamycin and; besides analytical methods more used for quantification of this molecule.

Microsponge-derived mini tablets loaded with immunosuppressive agents: Pharmacokinetic investigation in human volunteers, cell viability and IVIVC correlation

Sirolimus, a potent immunosuppressant, has been demonstrated to have remarkable activity in inhibiting allograft rejection in transplantation. The objective of the study was to fabricate microsponge mini tablets with enhanced solubility and bioavailability. β-Cyclodextrin and NEOCEL C91 were selected to prepare the microsponges (SLM-M) to improve the stability and solubility of sirolimus. The current study involved the quasi emulsion-solvent diffusion technique to design sirolimus-loaded microsponges that were further compressed into mini tablets 4 mm in diameter. Solid-state characterization, dissolution at different pH values, stability, and pharmacokinetic profiles with IVIVC data were analyzed in humans. Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) were used to characterize the formulations, and high-performance liquid chromatography (HPLC) was used to assess the drug stability of the compressed microsponge minitablets. The API changed from the crystalline state to an amorphous state, as shown by XRD and DSC. The compressed mini tablets showed a 4-fold enhancement in the drug dissolution profile. A toxicology investigation suggested that mini tablets were safe. In humans, the bioavailability of sirolimus compressed mini tablets from SLM-M was significantly improved. The results suggest that mini tablets prepared with β-cyclodextrin and NEOCEL C91 by a quasi emulsion-solvent diffusion process might be an alternative way to improve the bioavailability of sirolimus. In addition, the manufacturing process is easily scalable for the commercialization of drugs to market.

Bioproperties, Nanostructured System and Analytical and Bioanalytical Methods for Determination of Rapamycin: A Review

The drug rapamycin is a potent inhibitor of the mTOR complex, acting directly in the signaling cascade of this protein complex; interrupting cell proliferation, in addition to being an extremely efficient immunosuppressant. Currently this drug is being used in several types of cancer. Rapamycin has been a target of great interest within nanomedicine involving nanostructured systems for drug delivery aiming to increase the bioactivity and bioavailability of this drug. In addition, there is a constant search for analytical methods to identify and quantify this drug. Numerous high-performance liquid chromatography analytical techniques, mass spectrometry and immunoassay techniques have been employed efficiently in an attempt to develop increasingly sensitive analytical methods. Thus, this review sought to bring together current and relevant scientific works involving rapamycin and; besides analytical methods more used for quantification of this molecule.

Methodological issues in clinical trials of polycystic kidney disease: a focused review

The field of therapeutics in autosomal dominant polycystic kidney disease (ADPKD) has seen a significant expansion recently, as major clinical trials have provided promising evidence in favor of new disease-modifying drugs. Though these trials are encouraging, limitations are noticeable in the form of methodological issues that restrict the interpretation of results. In this review, we discuss the methodological pitfalls of high-profile clinical interventional trials for ADPKD which have been published since 2009. Issues in study design, patient selection and follow-up, analyses and reporting of results are presented. From this review, we highlight a number of suggestions for future improvement including designs to enrich a more homogeneous patient population (i.e. based on their age-adjusted total kidney volume and/or underlying mutation class) at high-risk for disease progression, appropriate study duration and patient sample size that are matched to the disease severity of the study patients, and the use of baseline characteristics (i.e. renal function, TKV, and the proportion of PKD1 and PKD2 patients) of the analyzed patients as a quality control measure to assess any potential imbalance in randomization. Furthermore, the recognition that TKV change is not a linear trait is important in both the study design and interpretation. Implementing these lessons learned from the published trials will greatly enhance the robustness and validity of future clinical trials in ADPKD.

mTOR inhibition with temsirolimus causes acute increases in glomerular permeability, but inhibits the dynamic permeability actions of puromycin aminonucleoside

Inhibitors of the mammalian target of rapamycin (mTORi) can produce de novo proteinuria in kidney transplant patients. On the other hand, mTORi has been shown to suppress disease progression in several animal models of kidney disease. In the present study, we investigated whether glomerular permeability can be acutely altered by the mTORi temsirolimus and whether mTORi can affect acute puromycin aminonucleoside (PAN) or angiotensin II (ANG II)-induced glomerular hyperpermeability. In anesthetized Wistar rats, the left ureter was cannulated for urine collection, while simultaneously blood access was achieved. Temsirolimus was administered as a single intravenous dose 30 min before the start of the experiments in animals infused with PAN or ANG II or in nonexposed animals. Polydispersed FITC-Ficoll-70/400 (molecular radius 10-80 Å) and (51)Cr-EDTA infusion was given during the whole experiment. Measurements of Ficoll in plasma and urine were performed sequentially before the temsirolimus injection (baseline) and at 5, 15, 30, 60, and 120 min after the start of the experiments. Urine and plasma samples were analyzed by high-performance size-exclusion chromatography (HPSEC) to assess glomerular sieving coefficients (θ) for Ficoll10-80Å. Temsirolimus per se increased baseline glomerular permeability to Ficoll50-80Å 45 min after its administration, a reactive oxygen species (ROS)-dependent phenomenon. PAN caused a rapid and reversible increase in glomerular permeability, peaking at 5 min, and again at 60-120 min, which could be blocked by the ROS scavenger tempol. mTORi abrogated the second permeability peak induced by PAN. However, it had no effect on the immediate ANG II- or PAN-induced increases in glomerular permeability.

Induction monotherapy with sirolimus has selected beneficial effects on glomerular and tubulointersititial injury in nephrotoxic serum nephritis

Background

The study aimed to test the hypothesis that therapeutic treatment with a mammalian target of rapamycin complex 1 inhibitor reduces renal cell proliferation and attenuates glomerular and tubulointerstitial injury in the early phase of nephrotoxic serum nephritis (NSN) in rats.

Methods

Male Wistar-Kyoto rats received a single tail-vein injection of sheep anti-rat glomerular basement membrane serum (day 0) and were treated with vehicle or sirolimus (0.25 mg/kg/day by subcutaneous injection) from day 1 until day 14.

Results

Treatment with sirolimus attenuated kidney enlargement by 41% (P<0.05), improved endogenous creatinine clearance by 50% (P<0.05), and reduced glomerular and tubulointerstitial cell proliferation by 53% and 70%, respectively, (P<0.05 compared to vehicle) in rats with NSN. In glomeruli, sirolimus reduced segmental fibrinoid necrosis by 69%, autologous rat immunoglobulin G deposition, glomerular capillary tuft enlargement, and periglomerular myofibroblast (α-smooth muscle actin-positive cells) accumulation (all P<0.05) but did not significantly affect glomerular crescent formation (P=0.15), macrophage accumulation (P=0.25), or the progression of proteinuria. In contrast, sirolimus preserved tubulointerstitial structure and attenuated all markers of injury (interstitial ED-1- and α-smooth muscle actin-positive cells and tubular vimentin expression; all P<0.05). By immunohistochemistry and Western blot analysis, sirolimus reduced the glomerular and tubulointerstitial expression of phosphorylated (Ser 235/236) S6-ribosomal protein (P<0.05).

Conclusion

Induction monotherapy with sirolimus suppressed target of rapamycin complex 1 activation, renal cell proliferation, and injury during the early stages of rodent NSN, but the degree of histological protection was more consistent in the tubulointerstitium than the glomerular compartment.

Efficacy and safety of mTOR inhibitor therapy in patients with early-stage autosomal dominant polycystic kidney disease: a meta-analysis of randomized controlled trials

BACKGROUND

The objective of this study was to conduct a meta-analysis of randomized controlled trials (RCTs) to present a profound review and an objective appraisal of the efficacy and safety of the mammalian target of rapamycin (mTOR) inhibitor therapy in patients with autosomal dominant polycystic kidney disease (ADPKD).

METHODS

RCTs involving the mTOR inhibitor therapy in patients with ADPKD are included. The data of studies and major outcomes include changes in patients' glomerular filtration rate (GFR), urinary protein, total kidney volume (TKV), cyst volume, parenchymal volume, and lipid profile and the frequency of adverse events. Review Manager 5.0 for meta-analysis was used in this study.

RESULTS

Up to January 31, 2011, 4 RCTs (with a total of 564 patients) were included. The mTOR inhibitor therapy group had smaller TKV than the control group [weighted mean difference (WMD) of TKV after treatment: -318.45, P = 0.04]. The mTOR inhibitor treatment does not necessarily slow down the aggravation of renal function in patients with ADPKD (WMD of GFR after therapy: 5.55, P < 0.01; at 6-month analyses = -0.97, P = 0.56). Side effects could occur during the mTOR inhibitor therapy, but the severities can be controlled by the appropriate use of drug.

CONCLUSIONS

Based on the current limited clinical trials, this study suggests that short-duration mTOR inhibitor therapy is relatively safe to slow down the increase in kidney volume in patients with early-stage ADPKD, but it has limited impact on slowing down the decrease in GFR.

Dose-dependent effects of sirolimus on mTOR signaling and polycystic kidney disease

Inhibition of the mammalian target of rapamycin (mTOR) shows beneficial effects in animal models of polycystic kidney disease (PKD); however, two clinical trials in patients with autosomal dominant PKD failed to demonstrate a short-term benefit in either the early or progressive stages of disease. The stage of disease during treatment and the dose of mTOR inhibitors may account for these differing results. Here, we studied the effects of a conventional low dose and a higher dose of sirolimus (blood levels of 3 ng/ml and 30-60 ng/ml, respectively) on mTOR activity and renal cystic disease in two Pkd1-mutant mouse models at different stages of the disease. When initiated at early but not late stages of disease, high-dose treatment strongly reduced mTOR signaling in renal tissues, inhibited cystogenesis, accelerated cyst regression, and abrogated fibrosis and the infiltration of immune cells. In contrast, low-dose treatment did not significantly reduce renal cystic disease. Levels of p-S6Rp(Ser240/244), which marks mTOR activity, varied between kidneys; severity of the renal cystic phenotype correlated with the level of mTOR activity. Taken together, these data suggest that long-term treatment with conventional doses of sirolimus is insufficient to inhibit mTOR activity in renal cystic tissue. Mechanisms to increase bioavailability or to target mTOR inhibitors more specifically to kidneys, alone or in combination with other compounds, may improve the potential for these therapies in PKD.

Neuroprotective, immunosuppressant and antineoplastic properties of mTOR inhibitors: current and emerging therapeutic options

The acronym mTOR defines a family of serine-threonine protein kinase called mammalian target of rapamycin. The major role of these kinases in the cell is to merge extracellular instructions with information about cellular metabolic resources and to control the rate of anabolic and catabolic processes accordingly. In mammalian cells mTOR is present in two distinct heteromeric protein complexes commonly referred to as mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2), involved in the control of a wide variety of cellular processes. It has been recently reported that compounds acting modulating mTOR activity, beside mediating the well recognized processes exploited in the anticancer and immunosuppressant effects, are provided with neuroprotective properties. In fact, mTOR is involved in the mechanism of PI3K/Akt-induced upregulation of glutamate transporter 1, GLT1, that is linked to several neuronal disorders such as stroke, Alzheimer's disease, and amyotrophic lateral sclerosis. Furthermore, in adult brain mTOR is crucial for numerous physiological processes such as synaptic plasticity, learning, memory, and brain control of food uptake. Moreover, the activation of mTOR pathway is involved in neuronal development, dendrite development and spine morphogenesis.

GSK3β inactivation in podocytes results in decreased phosphorylation of p70S6K accompanied by cytoskeletal rearrangements and inhibited motility

The inhibition of mTOR kinase after renal transplantation has been associated with podocyte injury and proteinuria; however, the signaling pathways regulating these effects are not well understood. We found that prolonged rapamycin treatment in podocytes leads to an increase in glycogen synthase kinase 3β (GSK3β) phosphorylation, resulting in inactivation of total GSK3β kinase activity. To investigate the cellular consequences of the inactivation of GSK3β, we used two inhibitors reducing kinase activity and studied the cross talk between GSK3 function and the Akt/mammalian target of rapamycin (mTOR) pathway. Both GSK3 inhibitors reduced the phosphorylation of the mTOR downstream target, p70(S6K), indicating that GSK3 inhibition in podocytes is able to cause similar effects as treatment with rapamycin. Moreover, GSK3 inhibition was accompanied by the reduced expression of slit diaphragm-associated proteins and resulted in an altered cytoskeletal structure and reduced motility of podocytes, suggesting that GSK3 kinase can modulate Akt/mTOR-dependent signaling in podocytes.