Candidate drugs against SARS-CoV-2 and COVID-19.

Outbreak and pandemic of coronavirus SARS-CoV-2 in 2019/2020 will challenge global health for the future. Because a vaccine against the virus will not be available in the near future, we herein try to offer a pharmacological strategy to combat the virus. There exists a number of candidate drugs that may inhibit infection with and replication of SARS-CoV-2. Such drugs comprise inhibitors of TMPRSS2 serine protease and inhibitors of angiotensin-converting enzyme 2 (ACE2). Blockade of ACE2, the host cell receptor for the S protein of SARS-CoV-2 and inhibition of TMPRSS2, which is required for S protein priming may prevent cell entry of SARS-CoV-2. Further, chloroquine and hydroxychloroquine, and off-label antiviral drugs, such as the nucleotide analogue remdesivir, HIV protease inhibitors lopinavir and ritonavir, broad-spectrum antiviral drugs arbidol and favipiravir as well as antiviral phytochemicals available to date may limit spread of SARS-CoV-2 and morbidity and mortality of COVID-19 pandemic.

Salinomycin as a drug for targeting human cancer stem cells.

Cancer stem cells (CSCs) represent a subpopulation of tumor cells that possess self-renewal and tumor initiation capacity and the ability to give rise to the heterogenous lineages of malignant cells that comprise a tumor. CSCs possess multiple intrinsic mechanisms of resistance to chemotherapeutic drugs, novel tumor-targeted drugs, and radiation therapy, allowing them to survive standard cancer therapies and to initiate tumor recurrence and metastasis. Various molecular complexes and pathways that confer resistance and survival of CSCs, including expression of ATP-binding cassette (ABC) drug transporters, activation of the Wnt/ß-catenin, Hedgehog, Notch and PI3K/Akt/mTOR signaling pathways, and acquisition of epithelial-mesenchymal transition (EMT), have been identified recently. Salinomycin, a polyether ionophore antibiotic isolated from Streptomyces albus, has been shown to kill CSCs in different types of human cancers, most likely by interfering with ABC drug transporters, the Wnt/ß-catenin signaling pathway, and other CSC pathways. Promising results from preclinical trials in human xenograft mice and a few clinical pilote studies reveal that salinomycin is able to effectively eliminate CSCs and to induce partial clinical regression of heavily pretreated and therapy-resistant cancers. The ability of salinomycin to kill both CSCs and therapy-resistant cancer cells may define the compound as a novel and an effective anticancer drug.

The "Big Five" Phytochemicals Targeting Cancer Stem Cells: Curcumin, EGCG, Sulforaphane, Resveratrol and Genistein.

Cancer stem cells (CSCs) constitute a subpopulation of tumor cells that possess self-renewal and tumor initiation capacity, and the ability to give rise to the heterogeneous lineages of cancer cells that comprise the tumor. CSCs exhibit intrinsic mechanisms of resistance to virtually all conventional cancer therapeutics, allowing them to survive current cancer therapies and to initiate tumor recurrence and metastasis. Different pathways and mechanisms that confer resistance and survival of CSCs, including activation of the Wnt/ß- catenin, Sonic Hedgehog, Notch, PI3K/Akt/mTOR and STAT3 signaling pathways, expression of aldehyde dehydrogenase 1 (ALDH1) and oncogenic microRNAs, and acquisition of epithelial-mesenchymal transition (EMT), have been identified recently. Certain phytochemicals, in particular curcumin, epigallocatechin-3-gallate (EGCG), sulforaphane, resveratrol and genistein have been shown to interfere with these intrinsic CSC pathways in vitro and in human xenograft mice, leading to elimination of CSCs. Moreover, recent clinical trials have demonstrated the therapeutic efficacy of five phytochemicals, alone or in combination with modern cancer therapeutics, and in various types of cancer. Since current cancer therapies fail to eradicate CSCs, leading to cancer recurrence and progression, targeting of CSCs with phytochemicals such as curcumin, EGCG, sulforaphane, resveratrol and genistein, combined with each other and/or in combination with conventional cytotoxic drugs and novel cancer therapeutics, may offer a novel therapeutic strategy against cancer.

Salinomycin overcomes ABC transporter-mediated multidrug and apoptosis resistance in human leukemia stem cell-like KG-1a cells.

Leukemia stem cells are known to exhibit multidrug resistance by expression of ATP-binding cassette (ABC) transporters which constitute transmembrane proteins capable of exporting a wide variety of chemotherapeutic drugs from the cytosol. We show here that human promyeloblastic leukemia KG-1a cells exposed to the histone deacetylase inhibitor phenylbutyrate resemble many characteristics of leukemia stem cells, including expression of functional ABC transporters such as P-glycoprotein, BCRP and MRP8. Consequently, KG-1a cells display resistance to the induction of apoptosis by various chemotherapeutic drugs. Resistance to apoptosis induction by chemotherapeutic drugs can be reversed by cyclosporine A, which effectively inhibits the activity of P-glycoprotein and BCRP, thus demonstrating ABC transporter-mediated drug resistance in KG-1a cells. However, KG-1a are highly sensitive to apoptosis induction by salinomycin, a polyether ionophore antibiotic that has recently been shown to kill human breast cancer stem cell-like cells and to induce apoptosis in human cancer cells displaying multiple mechanisms of drug and apoptosis resistance. Whereas KG-1a cells can be adapted to proliferate in the presence of apoptosis-inducing concentrations of bortezomib and doxorubicin, salinomycin does not permit long-term adaptation of the cells to apoptosis-inducing concentrations. Thus, salinomycin should be regarded as a novel and effective agent for the elimination of leukemia stem cells and other tumor cells exhibiting ABC transporter-mediated multidrug resistance.

Association of high IFN-gamma plasma levels with low B-cell counts in renal transplant recipients with stable long-term graft function.

Recently, we reported that patients with long-term stable good graft function had higher interferon-gamma (IFN-gamma) and lower IL-4 plasma levels late as compared with early post-transplant. These patients had more often detectable CD3(+)CD4(+)CD25(+)IFN-gamma(+)Foxp3(+) peripheral blood lymphocytes (PBL) late post-transplant than patients with impaired graft function. We therefore speculated that high plasma IFN-gamma late post-transplant might contribute to the maintenance of graft acceptance. Using ELISA and four-color flow cytometry, plasma cytokines and PBL subpopulations were measured in 65 renal transplant recipients with stable graft function late post-transplant. High IFN-gamma plasma levels were associated with low CD19(+) B PBL (r = -0.329; p = 0.009) and low activated CD3(+)CD8(+)DR(+) T PBL (r = -0.266; p = 0.035). Plasma IFN-gamma increased with time post-transplant (r = 0.288; p = 0.022) and was not associated with the dose of immunosuppressive drugs (p = n.s.). High plasma IFN-gamma was not associated with serum creatinine (r = 0.038; p = 0.765). Five patients showed evidence of chronic allograft nephropathy in previous biopsies and none of them exhibited increased plasma IFN-gamma. In patients with good long-term graft function, high IFN-gamma plasma levels were associated with low numbers of B PBL and activated CD8(+) T PBL. High IFN-gamma plasma levels might prevent the development of an immunological alloresponse and thereby contribute to the maintenance of graft acceptance.

Decreasing plasma soluble IL-1 receptor antagonist and increasing monocyte activation early post-transplant may be involved in pathogenesis of delayed graft function in renal transplant recipients.

Delayed graft function (DGF) increases the risk of acute allograft rejection and may affect long-term graft survival. We compared pre-transplant, early post-transplant, and late post-transplant serum creatinine (Cr) and plasma levels of neopterin, cytokines, and cytokine receptors/antagonists in patients with DGF (n = 39), slow graft function (SGF) (n = 43), or immediate graft function (IGF) (n = 30). Three and eight days post-transplant, plasma neopterin (p < 0.001; p < 0.001), Soluble Interleukin-6 (IL-6) receptor (R) (p = 0.002; p = 0.001), and IL-10 (p = 0.003; p = 0.001) were higher in DGF than IGF patients. One month post-transplant, plasma neopterin (p < 0.001) and IL-10 (p < 0.001) were higher in DGF than IGF patients. Three days post-transplant, the results indicated reduced sIL-1 receptor antognist (RA) production in DGF patients (p = 0.001). Simultaneously, plasma sIL-6R and IL-10 increased in DGF (p < 0.001; p = 0.003) and SGF (p = 0.007; p = 0.030) patients, indicating increased production of sIL-6R and IL-10. Lower sIL-1 production in DGF than IGF patients early post-transplant might promote the increased production of monocyte-derived neopterin, sIL-6R, and IL-10. This monocyte/macrophage activation might induce inflammation in the graft and subsequently cause an impairment of graft function. Blocking of monocyte activity after renal transplantation may be considered a potential approach for improving graft outcome.

Structural features of coronavirus SARS-CoV-2 spike protein: Targets for vaccination.

Various human pathogenic viruses employ envelope glycoproteins for host cell receptor recognition and binding, membrane fusion and viral entry. The spike (S) glycoprotein of betacoronavirus SARS-CoV-2 is a homotrimeric class I fusion protein that exists in a metastable conformation for cleavage by host cell proteases furin and TMPRSS2, thereby undergoing substantial structural rearrangement for ACE2 host cell receptor binding and subsequent viral entry by membrane fusion. The S protein is densely decorated with N-linked glycans protruding from the trimer surface that affect S protein folding, processing by host cell proteases and the elicitation of humoral immune response. Deep insight into the sophisticated structure of SARS-CoV-2 S protein may provide a blueprint for vaccination strategies, as reviewed herein.

Novel Drugs Targeting the SARS-CoV-2/COVID-19 Machinery.

Like other human pathogenic viruses, coronavirus SARS-CoV-2 employs sophisticated macromolecular machines for viral host cell entry, genome replication and protein processing. Such machinery encompasses SARS-CoV-2 envelope spike (S) glycoprotein required for host cell entry by binding to the ACE2 receptor, viral RNA-dependent RNA polymerase (RdRp) and 3-chymotrypsin-like main protease (3Clpro/Mpro). Under the pressure of the accelerating COVID-19 pandemic caused by the outbreak of SARS-CoV-2 in Wuhan, China in December 2019, novel and repurposed drugs were recently designed and identified for targeting the SARS-CoV-2 reproduction machinery, with the aim to limit the spread of SARS-CoV-2 and morbidity and mortality due to the COVID-19 pandemic.

Proteasome inhibition activates the mitochondrial pathway of apoptosis in human CD4+ T cells.

We have previously shown that inhibition of the proteolytic activity of the proteasome induces apoptosis and suppresses essential functions of activated human CD4(+) T cells, and we report now the detailed mechanisms of apoptosis following proteasome inhibition in these cells. Here we show that proteasome inhibition by bortezomib activates the mitochondrial pathway of apoptosis in activated CD4(+) T cells by disrupting the equilibrium of pro-apoptotic and anti-apoptotic proteins at the outer mitochondrial membrane (OMM) and by inducing the generation of reactive oxygen species (ROS). Proteasome inhibition leads to accumulation of pro-apoptotic proteins PUMA, Noxa, Bim and p53 at the OMM. This event provokes mitochondrial translocation of activated Bax and Bak homodimers, which induce loss of mitochondrial membrane potential (DeltaPsim). Breakdown of DeltaPsim is followed by rapid release of pro-apoptotic Smac/DIABLO and HtrA2 from mitochondria, whereas release of cytochrome c and AIF is delayed. Cytoplasmic Smac/DIABLO and HtrA2 antagonize IAP-mediated inhibition of partially activated caspases, leading to premature activation of caspase-3 followed by activation of caspase-9. Our data show that proteasome inhibition triggers the mitochondrial pathway of apoptosis by activating mutually independent apoptotic pathways. These results provide novel insights into the mechanisms of apoptosis induced by proteasome inhibition in activated T cells and underscore the future use of proteasome inhibitors for immunosuppression.

Salinomycin induces apoptosis and overcomes apoptosis resistance in human cancer cells.

Salinomycin is a polyether antibiotic isolated from Streptomyces albus that acts in different biological membranes as a ionophore with a preference for potassium. It is widely used as an anticoccidial drug in poultry and is fed to ruminants to improve nutrient absorption and feed efficiency. Salinomycin has recently been shown to selectively deplete human breast cancer stem cells from tumorspheres and to inhibit breast cancer growth and metastasis in mice. We show here that salinomycin induces massive apoptosis in human cancer cells of different origin, but not in normal cells such as human T lymphocytes. Moreover, salinomycin is able to induce apoptosis in cancer cells that exhibit resistance to apoptosis and anticancer agents by overexpression of Bcl-2, P-glycoprotein or 26S proteasomes with enhanced proteolytic activity. Salinomycin activates a distinct apoptotic pathway that is not accompanied by cell cycle arrest and that is independent of tumor suppressor protein p53, caspase activation, the CD95/CD95L system and the proteasome. Thus, salinomycin should be considered as a novel and effective anticancer agent that overcomes multiple mechanisms of apoptosis resistance in human cancer cells.

Adaptive modification and flexibility of the proteasome system in response to proteasome inhibition.

The highly conserved ubiquitin-proteasome system is the principal machinery for extralysosomal protein degradation in eukaryotic cells. The 26S proteasome, a large multicatalytic multisubunit protease that processes cell proteins by limited and controlled proteolysis, constitutes the central proteolytic component of the ubiquitin-proteasome system. By processing cell proteins essential for development, differentiation, proliferation, cell cycling, apoptosis, gene transcription, signal transduction, senescence, and inflammatory and stress response, the 26S proteasome plays a key role in the regulation and maintenance of basic cellular processes. Various synthetic and biologic inhibitors with different inhibitory profiles towards the proteolytic activities of the 26S proteasome have been identified recently. Such proteasome inhibitors induce apoptosis and cell cycle arrest preferentially in neoplastic cells. Based on these findings proteasome inhibitors became useful in cancer therapy. However, under the pressure of continuous proteasome inhibition, eukaryotic cells can develop complex adaptive mechanisms to subvert the lethal attack of proteasome inhibitors. Such mechanisms include the adaptive modification of the proteasome system with increased expression, enhanced proteolytic activity and altered subcomplex assembly and subunit composition of proteasomes as well as the expression of a giant oligomeric protease complex, tripeptidyl peptidase II, which partially compensates for impaired proteasome function. Here we review the adaptive mechanisms developed by eukaryotic cells in response to proteasome inhibition. These mechanisms reveal enormous flexibility of the proteasome system and may have implications in cancer biology and therapy.

Proteasome inhibition suppresses essential immune functions of human CD4+ T cells.

The proteasome constitutes the central proteolytic component of the highly conserved ubiquitin-proteasome system, which is required for the maintenance and regulation of basic cellular processes, including differentiation, proliferation, cell cycling, gene transcription and apoptosis. Here we show that inhibition of proteasomal proteolytic activity by the proteasome inhibitors bortezomib and lactacystin suppresses essential immune functions of human CD4(+) T cells activated by allogeneic dendritic cells (DCs). In activated CD4(+) T cells, proteasome inhibition induces apoptosis accompanied by rapid accumulation and stabilization of the tumour suppressor protein p53. Activated CD4(+) T cells surviving proteasome inhibition undergo inhibition of proliferation by induction of G(1) phase cell-cycle arrest. Induction of G(1) arrest is accompanied by the accumulation of cyclin-dependent kinase inhibitors p21(WAF1/CIP1) and p27(KIP1) and the disappearance of cyclin A, cyclin D2 and proliferating cell nuclear antigen, proteins known to regulate G(1) to S phase cell-cycle transitions. Expression of the activation-associated cell surface receptors CD25, CD28, CD120b and CD134 as well as production of interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), interleukin-4 (IL-4) and IL-5 is suppressed in response to proteasome inhibition in CD4(+) T cells activated by DCs. Expression of CD25, IFN-gamma, TNF-alpha, IL-4 and IL-5 is known to be mediated by the transcriptional activity of nuclear factor of activated T cells (NFAT), and we show here that proteasome inhibition suppresses activation and nuclear translocation of NFATc2 in activated CD4(+) T cells. Thus, the proteasome is required for essential immune functions of activated CD4(+) T cells and can be defined as a molecular target for the suppression of deregulated and unwanted T-cell-mediated immune responses.

HMG-CoA reductase inhibitor simvastatin overcomes bortezomib-induced apoptosis resistance by disrupting a geranylgeranyl pyrophosphate-dependent survival pathway.

Simvastatin is a competitive inhibitor of HMG-CoA reductase, the rate-limiting enzyme of the mevalonate pathway required for the biosynthesis of cholesterol and higher isoprenoids such as geranylgeranyl pyrophosphate (GGPP). Apart from its capacity to lower cholesterol plasma levels and to protect against cardiovascular disease, simvastatin induces apoptosis in various cancer cells. We have generated human Namalwa Burkitt lymphoma cells that display general apoptosis resistance and hyperproliferation due to increased expression and proteolytic activity of 26S proteasomes in response to continuous treatment of the cells with the proteasome inhibitor bortezomib. In these cells, simvastatin does not inhibit proteasome activity, but induces apoptosis, G2/M cell cycle arrest and accumulation of p21(Waf1/Cip1), and effectively inhibits hyperproliferation. These effects are reversed by the addition of GGPP. GGPP-dependent plasma membrane localization of the small GTPase RhoA that is required for RhoA-mediated oncogenic signaling is completely inhibited by simvastatin. Finally, bortezomib but not simvastatin induces accumulation and stabilization of the anti-apoptotic protein Mcl-1, which is known to confer resistance to apoptosis in cancer cells. Thus, simvastatin overcomes bortezomib-induced apoptosis resistance by inhibiting synthesis of GGPP and disrupting a GGPP-dependent survival pathway.

Dysregulated cytokine responses during cytomegalovirus infection in renal transplant recipients.

OBJECTIVE: Pre- and posttransplant predisposing factors for cytomegalovirus (CMV) activation and disease are not well defined. The aim of this study was to examine whether there are differences in plasma cytokine levels pretransplant, before and during CMV replication in renal transplant recipients. MATERIAL AND METHODS: We studied 76 renal transplant recipients in whom CMV-DNA was studied at regular intervals posttransplant. Thirty-eight patients developed CMV viremia posttransplant (CMV-DNA-positive). Thirty-eight patients had no detectable CMV-DNA posttransplant (CMV-DNA-negative). Cytokine and cytokine receptors/antagonists plasma levels were measured pretransplant, and pre-, during, and after CMV-viremia in CMV-DNA-positive patients and at similar time points in CMV-DNA-negative transplant recipients. RESULTS: Compared with pretransplant, after transplantation soluble (s) plasma interleukin (IL)-2 receptor (R), IL-6, and interferon-gamma (IFN-gamma) decreased in both groups (CMV-DNA-positive: P=0.002; P=0.028; P=0.032; CMV-DNA-negative: P=0.001; P=0.040; P=0.030) whereas IL-10 remained constant in both groups (P=n.s.). During CMV viremia, sIL-2R (P=0.015) and IL-6 (P=0.006) increased compared with previremia but remained constant in CMV-DNA-negative patients matched for the day of investigation (P=n.s.). Simultaneously, IFN-gamma increased in CMV-DNA-negative patients (P=0.008) and remained constant in CMV-DNA-positive patients (P=n.s.). During CMV viremia, IL-10 (P=0.002) and sIL-2R (P=0.007) were significantly higher in CMV-DNA-positive than CMV-DNA-negative patients investigated at similar time points. CONCLUSION: Our results indicate that CMV replication in renal transplant recipients is associated with increased sIL-2R, IL-6, and IL-10 and decreased IFN-gamma plasma levels, pointing to a monocyte/Th2 activation and a Th1 blockade. The high IL-10 might decrease the IFN-gamma plasma levels in CMV-DNA-positive patients. Th1 deficiency in CMV-DNA-positive patients might promote development of CMV disease.

Concise review: role and function of the ubiquitin-proteasome system in mammalian stem and progenitor cells.

Highly ordered degradation of cell proteins by the ubiquitin-proteasome system, a sophisticated cellular proteolytic machinery, has been identified as a key regulatory mechanism in many eukaryotic cells. Accumulating evidence reveals that the ubiquitin-proteasome system is involved in the regulation of fundamental processes in mammalian stem and progenitor cells of embryonic, neural, hematopoietic, and mesenchymal origin. Such processes, including development, survival, differentiation, lineage commitment, migration, and homing, are directly controlled by the ubiquitin-proteasome system, either via proteolytic degradation of key regulatory proteins of signaling and gene expression pathways or via nonproteolytic mechanisms involving the proteasome itself or posttranslational modifications of target proteins by ubiquitin or other ubiquitin-like modifiers. Future characterization of the precise roles and functions of the ubiquitin-proteasome system in mammalian stem and early progenitor cells will improve our understanding of stem cell biology and may provide an experimental basis for the development of novel therapeutic strategies in regenerative medicine. Disclosure of potential conflicts of interest is found at the end of this article.

Antithymocyte globulins suppress dendritic cell function by multiple mechanisms.

BACKGROUND: The polyclonal rabbit antithymocyte and anti-T-cell immunoglobulins (ATGs) Thymoglobulin (TG) and ATG-Fresenius S (ATG-F) have been widely used for the prevention and therapy of allograft rejection and graft versus host disease in transplantation. Although immunosuppressive mechanisms of ATGs on T cells are well studied, less is known about their impact on dendritic cells (DCs). METHODS: Effects of TG and ATG-F on immune functions and signaling pathways of human monocyte-derived DCs were determined by flow cytometry, enzyme-linked immunosorbent assay, Western blot, apoptosis assays, endocytosis assays, and T cell stimulation assays. RESULTS: TG and ATG-F bind rapidly and with high affinity to CD11c, CD80, CD86, CD40, CD36, CD38, CD206, and human leukocyte antigen-DR on DCs. TG and, to a lesser extent, ATG-F induce apoptosis in immature and mature DCs. Macropinocytotic and receptor-mediated endocytotic antigen uptake in immature DCs is inhibited by TG and ATG-F due to their binding of the C-type lectins CD206 and CD209. TG and ATG-F induce activation of the mitogen-activated protein kinases ERK1/2 and p38 that contributes to the induction of apoptosis. TG and ATG-F also induce cytoplasmic-nuclear translocation of the NF-kappaB/Rel transcription factors RelB, RelA, p50, and p52. Production of interleukin-12p70 in mature DCs is suppressed by TG and ATG-F. TG and ATG-F reduce the capacity of mature DCs to stimulate allogeneic and autologous T cells. CONCLUSIONS: ATGs interfere with basic DC functions, suggesting that DCs are relevant targets for the immunosuppressive action of ATGs in transplantation.

Short communication: decreasing soluble CD30 and increasing IFN-gamma plasma levels are indicators of effective highly active antiretroviral therapy.

It was previously reported that without highly active antiretroviral therapy (HAART), secretion of Th1 cytokines and antiviral IFN-gamma in HIV-infected patients is decreased, whereas the production of Th2 cytokines, proinflammatory cytokines, and TNF-alpha is increased. We studied the effect of HAART on Th1-, Th2-, and monocyte-derived cytokines, and on the Th2-type immune response marker soluble (s)CD30 in HIV-1-infected hemophilia patients. Viral Load (VL), CD4+ lymphocyte counts, and plasma levels of sIL-1RA, IL-2, sIL-2R, IL-3, IL-4, IL-6, sIL-6R, IL-7, IL-10, TNF-alpha, TGF-beta2, IFN-gamma, and sCD30 were measured in 18 patients who received HAART. Nine patients were initially treatment-naive and were monitored after the initiation of HAART. sCD30 median levels were significantly higher in treatment-naive patients than in patients who were on HAART (77 vs. 30 U/ml, p = 0.005). A strong association was observed between sCD30 and VL (r = 0.85, p = 0.004). After the initiation of HAART, sCD30 levels decreased and remained low (at 1 year, 38; at 2 years, 41 U/ml; p = 0.012 and p = 0.021, respectively, as compared to baseline level) and this was accompanied by a decrease in VL and monocyte-derived IL-6 and an increase in CD4+ lymphocyte counts and Th1-derived IFN-gamma. One year after the initiation of HAART a strong inverse correlation was observed between IFN-gamma and VL (r = -0.83, p = 0.006). In contrast to sCD30 and IFN-gamma, CD4 counts and plasma IL-6 did not correlate with VL at any time. Our data suggest that decreasing sCD30 and increasing IFN-gamma plasma levels are indicators of effective HAART treatment and CD4 Th1 cell recovery in HIV-infected patients.

Disassociation between risk of graft loss and risk of non-Hodgkin lymphoma with induction agents in renal transplant recipients.

BACKGROUND: It is widely assumed that the graft-enhancing properties of antilymphocyte induction agents and their lymphoma-inducing potential are intimately related. METHODS: The Collaborative Transplant Study (CTS) database was used to evaluate graft survival and non-Hodgkin lymphoma at 3 years according to type of induction in 112,122 patients receiving a deceased-donor renal transplant during 1985 to 2004. RESULTS: The relative risk of 3-year graft loss versus no induction was 1.07 (95% confidence interval [CI], 1.01-1.13; P=0.016) with murine anti-CD3 monoclonal antibody (OKT3), 1.03 (95% CI, 0.95-1.11; NS) with antithymocyte globulin (ATG)-Fresenius, 1.18 (95% CI, 1.02-1.35; P=0.021) with ATGAM, 0.74 (95% CI, 0.68-0.81; P<0.001) with Thymoglobulin, and 0.78 (95% CI, 0.72-0.84; P<0.001) with interleukin (IL)-2RA induction. The standardized incidence ratio of lymphoma compared with a similar nontransplant population was 21.5 (95% CI, 15.7-28.8; P<0.001) with OKT3, 4.9 (95% CI, 1.6-11.5; P=0.008) with ATG-Fresenius, 29.0 (95% CI, 12.5-57.1; P<0.001) with ATGAM, 21.6 (95% CI, 14.3-31.2; P<0.001) with Thymoglobulin, 7.8 (95% CI, 4.4-12.9; P<0.001) with IL-2RAs, and 9.4 (95% CI, 8.3-10.6 P<0.001) with no induction. CONCLUSIONS: Those agents that offered the highest rates of graft survival were not necessarily associated with the highest risk of lymphoma. Graft survival was significantly improved with Thymoglobulin and IL-2RA induction, whereas lymphoma rates were highest with ATGAM, OKT3, and Thymoglobulin. IL-2RA agents seem to offer the best risk-to-benefit ratio for this patient population overall in terms of graft survival and lymphoma.

Association of high pretransplant sIL-6R plasma levels with acute tubular necrosis in kidney graft recipients.

BACKGROUND: Delayed graft function is primarily caused by acute tubular necrosis (ATN). We studied in renal transplant recipients with posttransplant graft biopsy whether an up-regulated immune system in the recipient immediately before transplantation affects the risk of developing ATN and might be relevant for the pathogenesis of ATN. METHODS: In a retrospective study, we analyzed pretransplant and early posttransplant soluble interleukin (sIL)-1RA, interleukin (IL)-2, sIL-2R, IL-3, IL-4, IL-6, sIL-6R, IL-10, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta2, interferon (IFN)-gamma, and neopterin plasma levels in patients with ATN (n=26). Matched patients with acute rejection (AR) (n=26) or normal posttransplant biopsy (n=26) served as controls. RESULTS: Pretransplant sIL-6R was higher (P=0.0004) and pretransplant TGF-beta2 lower (P=0.002) in patients with ATN than in patients with normal biopsy. ROC curves showed that high pretransplant sIL-6R has a high sensitivity (77%) and high specificity (64%) for ATN (P=0.002). Posttransplant plasma sIL-6R continued to be higher in ATN patients than in patients with normal biopsy (P=0.001). Patients with acute rejection showed pre- and posttransplant sIL-6R and TGF-beta2 plasma levels similar to those of patients with normal biopsy (P=NS). CONCLUSION: High pretransplant sIL-6R plasma levels are associated with an increased risk of ATN and might contribute to the development of ATN early posttransplant. Our data suggest that preactivation of the recipient's immune system increases the risk of ATN.