The change of immunosuppressive regimen from calcineurin inhibitors to mammalian target of rapamycin (mTOR) inhibitors and its effect on malignancy following heart transplantation

Rapamycin inhibits B16 melanoma cell viability invitro and invivo by inducing autophagy and inhibiting the mTOR/p70‑S6k pathway

Rapamycin is an immunosuppressant that has been shown to prevent tumor growth following organ transplantation. However, its exact mode of antitumor action remains unknown. The present study used the B16-F10 (B16) murine melanoma model to explore the antitumor mechanism of rapamycin, and it was revealed that rapamycin reduced B16 cell viability in vitro and in vivo. In addition, in vitro and in vivo, the results of western blotting showed that rapamycin reduced Bcl2 expression, and enhanced the protein expression levels of cleaved caspase 3 and Bax, indicating that it can induce the apoptosis of B16 melanoma cells. Furthermore, the results of cell cycle analysis and western blotting showed that rapamycin induced B16 cell cycle arrest in the G1 phase, based on the reduction in the protein expression levels of CDK1, cyclin D1 and CDK4, as well as the increase in the percentage of cells in G1 phase. Rapamycin also significantly increased the number of autophagosomes in B16 melanoma cells, as determined by transmission electron microscopy. Furthermore, the results of RT-qPCR and western blotting showed that rapamycin upregulated the protein expression levels of microtubule-associated protein light chain 3 (LC3) and Beclin-1, while downregulating the expression of p62 in vitro and in vivo, thus indicating that rapamycin could trigger cellular autophagy. The present study revealed that rapamycin in combination with chloroquine (CQ) further increased LC3 expression compared with that in the CQ group, suggesting that rapamycin induced an increase in autophagy in B16 cells. Furthermore, the results of western blotting showed that rapamycin blocked the phosphorylation of p70 ribosomal S6 kinase (p70-S6k) and mammalian target of rapamycin (mTOR) proteins in vitro and in vivo, thus suggesting that rapamycin may exert its antitumor effect by inhibiting the phosphorylation of the mTOR/p70-S6k pathway. In conclusion, rapamycin may inhibit tumor growth by inducing cellular G1 phase arrest and apoptosis. In addition, rapamycin may exert its antitumor effects by inducing the autophagy of B16 melanoma cells in vitro and in vivo, and the mTOR/p70-S6k signaling pathway may be involved in this process.

Heart Transplantation

Heart transplantation (HTx) remains the last therapeutic resort for patients with advanced heart failure. The present work is a clinically focused review discussing current issues in heart transplantation. Several factors have been associated with the outcome of HTx, such as ABO and HLA compatibility, graft size, ischemic time, age, infections, and the cause of death, as well as imaging and laboratory tests. In 2018, UNOS changed the organ allocation policy for HTx. The aim of this change was to prioritize patients with a more severe clinical condition resulting in a reduction in mortality of people on the waiting list. Advanced heart failure and resistant angina are among the main indications of HTx, whereas active infection, peripheral vascular disease, malignancies, and increased body mass index (BMI) are important contraindications. The main complications of HTx include graft rejection, graft angiopathy, primary graft failure, infection, neoplasms, and retransplantation. Recent advances in the field of HTx include the first two porcine-to-human xenotransplantations, the inclusion of hepatitis C donors, donation after circulatory death, novel monitoring for acute cellular rejection and antibody-mediated rejection, and advances in donor heart preservation and transportation. Lastly, novel immunosuppression therapies such as daratumumab, belatacept, IL 6 directed therapy, and IgG endopeptidase have shown promising results.

Everolimus-Induced Immune Effects after Heart Transplantation: A Possible Tool for Clinicians to Monitor Patients at Risk for Transplant Rejection

Background: Patients treated with an inhibitor of the mechanistic target of rapamycin (mTORI) in a calcineurin inhibitor (CNI)-free immunosuppressive regimen after heart transplantation (HTx) show a higher risk for transplant rejection. We developed an immunological monitoring tool that may improve the identification of mTORI-treated patients at risk for rejection. Methods: Circulating dendritic cells (DCs) and regulatory T cells (T_regs) were analysed in 19 mTORI- and 20 CNI-treated HTx patients by flow cytometry. Principal component and cluster analysis were used to identify patients at risk for transplant rejection. Results: The percentages of total T_regs (p = 0.02) and CD39⁺ T_regs (p = 0.05) were higher in mTORI-treated patients than in CNI-treated patients. The principal component analysis revealed that BDCA1⁺, BDCA2⁺ and BDCA4⁺ DCs as well as total T_regs could distinguish between non-rejecting and rejecting mTORI-treated patients. Most mTORI-treated rejectors showed higher levels of BDCA2⁺ and BDCA4⁺ plasmacytoid DCs and lower levels of BDCA1⁺ myeloid DCs and T_regs than mTORI non-rejectors. Conclusion: An mTORI-based immunosuppressive regimen induced a sufficient, tolerance-promoting reaction in T_regs, but an insufficient, adverse effect in DCs. On the basis of patient-specific immunological profiles, we established a flow cytometry-based monitoring tool that may be helpful in identifying patients at risk for rejection.

Application of Immune Checkpoint Inhibitors in Solid Organ Transplantation Recipients: A Systematic Review

BACKGROUND

Solid organ transplantation (SOT) is a treatment method for end-stage organ diseases and improve their life quality, while using long-term immunosuppressant drugs (ISD) is needed to suppress the function of the immune system. Immune checkpoint inhibitors (ICIs) are a class of anti-tumor drugs that kill tumors by activating the autoimmune system. The primary objective of our systematic review is to investigate the risk factors for organ rejection and the efficacy of ICIs in solid organ transplantation recipients (SOTRs).

METHODS

We searched four databases to find relevant articles up to January 2021. A total of 61 articles involving 106 SOTRs met the screening criteria and were included in our systematic review. The collected data were statistical described, and the risk factors were analyzed by logistic regression.

RESULTS

Forty-four patients (41.5%) developed host-versus-graft response (HVGR) after ICIs. mTOR inhibitors (pre-ICIs) (p = 0.069, OR = 0.377, 95% CI 0.132-1.078) and calcineurin inhibitors (post-ICIs) (p = 0.056, OR = 0.375, 95%CI 0.137-1.025) may help reduce the incidence of HVGR. Hormones (pre-ICIs) (p = 0.026, OR = 3.150, 95%CI 1.150-8.628) and anti-metabolites (pre-ICIs) (p = 0.022, OR = 3.214, 95%CI 1.185-8.720) may adversely affect the efficacy of ICIs. Only 35.6% of patients both responded well to ICIs treatment and did not develop HVGR.

CONCLUSIONS

Our systematic review summarizes the use of ICIs in SOTRs and evaluates the efficacy of ICIs and the risk factors that induce HVGR. Through risk factor analysis, we found that mTOR inhibitors and calcineurin inhibitors may help to reduce the occurrence of HVGR; hormones and anti-metabolic drugs may have adverse effects on the efficacy of ICIs. In addition, there is a contradictory relationship between the occurrence of HVGR and the efficacy of ICIs.

Potential of Anti-Cancer Activity of Secondary Metabolic Products from Marine Fungi

The promising feature of the fungi from the marine environment as a source for anticancer agents belongs to the fungal ability to produce several compounds and enzymes which contribute effectively against the cancer cells growth. L-asparaginase acts by degrading the asparagine which is the main substance of cancer cells. Moreover, the compounds produced during the secondary metabolic process acts by changing the cell morphology and DNA fragmentation leading to apoptosis of the cancer cells. The current review has analyed the available information on the anticancer activity of the fungi based on the data extracted from the Scopus database. The systematic and bibliometric analysis revealed many of the properties available for the fungi to be the best candidate as a source of anticancer drugs. Doxorubicin, actinomycin, and flavonoids are among the primary chemical drug used for cancer treatment. In comparison, the most anticancer compounds producing fungi are Aspergillus niger, A. fumigatus A. oryzae, A. flavus, A. versicolor, A. terreus, Penicillium citrinum, P. chrysogenum, and P. polonicum and have been used for investigating the anticancer activity against the uterine cervix, pancreatic cancer, ovary, breast, colon, and colorectal cancer.

Skin cancers in Italian lung transplant recipients: Incidence and risk factors analysis

Only a few studies reported the incidence and risk factors of skin cancers in lung transplant recipients. The aim of this study was to determine the cumulative incidence of skin cancers in a cohort of patients undergoing lung transplantation and to define predictors of their development. About 247 consecutive patients receiving lung transplantation at the Thoracic Surgery Unit of University Hospital of Padova between May 1995 and October 2016 were studied. Cumulative incidence of skin cancers was estimated considering death as a competing event. The effect of potential predictors was evaluated with univariate and multivariable Cox models for competing risks. About 37 (15.0%) patients developed skin tumors. The cumulative incidence of any skin cancer was 14.2% at 5 years, 21.4% at 10 years, and 24.3% at 15 years posttransplantation. Age at transplantation, male gender, phototype II, and voriconazole use were independent risk factors for development of squamous cell carcinoma. Only male gender and phototype II were independent risk factors for development of basal cell carcinoma. Since lung transplant recipients have a greater risk of developing skin cancers, the management of these patients needs a multidisciplinary approach, in which dermatologists and transplant physicians have a primary role.

Association between infectious event and de novo malignancy after heart transplantation

The aim of the study was to investigate the incidence of and risk factors for de novo malignancy after heart transplantation (HTx) in a single center. We assessed 102 consecutive patients who received HTx and were followed-up in our center regularly for > 1 year from June 2006 to May 2018. We investigated the incidence of and risk factors for de novo malignancy. The cumulative incidence of each malignancy type during the follow-up period was one (0.98%) for skin cancer, four (3.92%) for nonskin solid organ cancer, and six (5.88%) for posttransplant lymphoproliferative disorder (PTLD). The percentage of patients with more than one infectious event ≤ 1 year after HTx was higher in the malignancy group than in the non-malignancy group. Furthermore, Kaplan-Meier analysis revealed that the incidence rate of infectious events was higher in patients with malignancies than in those without (log-rank P < 0.001). After dividing malignancies into a PTLD group and a solid organ malignancy group, we found that negative Epstein-Barr virus serostatus, cytomegalovirus-positive antigenemia, and the occurrence of any viral or gastrointestinal infectious event at ≤ 1 year were more frequent in patients with PTLD than in patients without it. The survival rate was significantly lower for patients with solid organ malignancy than for patients without malignancy. In conclusion, there was a correlation between infectious events and de novo malignancy, particularly in patients with PTLD. We should confirm this finding by conducting a larger cohort study.

Characterization of regulatory T cell expansion for manufacturing cellular immunotherapies

Regulatory T cells (T_regs) are critical mediators of peripheral immune tolerance. T_regs suppress immune activation against self-antigens and are the focus of cell-based therapies for autoimmune diseases. However, T_regs circulate at a very low frequency in blood, limiting the number of cells that can be isolated by leukapheresis. To effectively expand T_regsex vivo for cell therapy, we report the metabolic modulation of T cells using mono-(6-amino-6-deoxy)-β-cyclodextrin (βCD-NH₂) encapsulated rapamycin (Rapa). Encapsulating Rapa in β-cyclodextrin increased its aqueous solubility ∼154-fold and maintained bioactivity for at least 30 days. βCD-NH₂-Rapa complexes (CRCs) enriched the fraction of CD4⁺CD25⁺FoxP3⁺ mouse T (mT) cells and human T (hT) cells up to 6-fold and up to 2-fold respectively and suppressed the overall expansion of effector T cells by 5-fold in both species. Combining CRCs and transforming growth factor beta-1 (TGF-β1) synergistically promoted the expansion of CD4⁺CD25⁺FoxP3⁺ T cells. CRCs significantly reduced the fraction of pro-inflammatory interferon-gamma (IFN-γ) expressing CD4⁺ T cells, suppressing this Th1-associated cytokine while enhancing the fraction of IFN-γ^- tumor necrosis factor-alpha (TNF-α) expressing CD4⁺ T cells. We developed a model using kinetic rate equations to describe the influence of the initial fraction of naïve T cells on the enrichment of T_regsin vitro. The model related the differences in the expansion kinetics of mT and hT cells to their susceptibility for immunophenotypic modulation. CRCs may be an effective and potent means for phenotypic modulation of T cells and the enrichment of T_regsin vitro. Our findings contribute to the development of experimental and analytical techniques for manufacturing T_reg based immunotherapies.