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.

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.

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.

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.

Monoclonal antibodies against human cancer stem cells.

Cancer stem cells (CSCs) are a subpopulation of tumor cells that display self-renewal and tumor initiation capacity and the ability to give rise to the heterogenous lineages of cancer cells that comprise the tumor. CSCs exhibit intrinsic mechanisms of resistance to modern cancer therapeutics, allowing them to survive current cancer therapies and to initiate tumor recurrence and metastasis. Various cell surface and transmembrane proteins expressed by CSCs, including CD44, CD47, CD123, EpCAM (CD326), CD133, IGF receptor I, and proteins of the Notch and Wnt signaling pathways have been identified. Recently, monoclonal antibodies and antibody constructs raised against these CSC proteins have shown efficacy against CSCs in human cancer xenograft mice, and some of them have demonstrated antitumor activity in clinical studies. Since current cancer therapies fail to eliminate CSCs, leading to cancer recurrence and progression, selective targeting of CSCs with monoclonal antibodies and antibody constructs may represent a novel therapeutic strategy against cancer.

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.

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.

Increased peripheral blood leukocyte subsets with regulatory phenotype in clinically stable long-term HIV-infected hemophilia patients on HAART may be beneficial and contribute to a decrease in autoimmunity.

After initiation of highly-active antiretroviral therapy (HAART), long-term HIV-infected hemophilia patients have been shown to lose autoantibodies against CD4(+) peripheral blood leukocytes (PBL), suggesting that HAART induces autoimmunity-blocking mechanisms. We compared cytokine levels and subpopulations of lymphocytes and dendritic cells (DC) in the blood of 40 long-term HIV(+) patients with those of 13 long-term HIV(-) hemophilia patients; 23 HIV(+) patients had a detectable retroviral load. Cell subsets were determined using flow cytometry and cytokine levels were measured using ELISA. HIV(+) patients showed higher proportions of DC subpopulations with immunostimulatory phenotypes (p < 0.01), CD8(+) PBL (p < 0.001), and IL-2 (p < 0.001) and sIL-2R plasma levels (p = 0.002) than HIV(-) patients. They also exhibited increased proportions of T PBL with immunosuppressive phenotypes such as CD3(+)CD4(+)CD25(+)Foxp3(+) (p = 0.001), and CD3(+)CD8(+)CD28(-)Foxp3(+) PBL (p < 0.001), and a decreased IL-7R expression on CD3(+)CD8(+) PBL (p = 0.001) compared to HIV(-) patients. Frequencies of CD3(+)CD4(+)CD25(+) PBL producing IL-2, IL-4, IL-10, IL-12, and/or IFN-gamma, and of CD3(+)CD4(+)CD28(-) PBL secreting IL-2 and/or IL-4 were lower in HIV(+) than in HIV(-) patients (p

Salinomycin in cancer: A new mission for an old agent.

Salinomycin is a monocarboxylic polyether ionophore isolated from Streptomyces albus that has been used for more than 30 years as an agricultural antibiotic to prevent coccidiosis in poultry and to improve nutrient absorption and feed efficiency in ruminants and swine. As a inonophore with strict selectivety for alkali ions and a strong preference for potassium, salinomycin interferes with transmembrane potassium potential and promotes the efflux of K+ ions from mitochondria and cytoplasm. Salinomycin has recently been shown to kill human cancer stem cells and to inhibit breast cancer growth and metastasis in mice. Salinomycin is also able to induce massive apoptosis in human cancer cells of different origins that display multiple mechanisms of drug and apoptosis resistance. Salinomycin activates an unconventional pathway of apoptosis in human cancer cells that may contribute to the breakdown of apoptosis resistance. The ability of salinomycin to effectively kill both cancer stem cells and apoptosis-resistant cancer cells may define the compound as a novel and effective anticancer agent.

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.

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.

Urinary proinflammatory cytokine response in renal transplant recipients with polyomavirus BK viruria.

BACKGROUND: Polyomavirus BK (BKV) has emerged as an important complication after kidney transplantation. BKV-associated nephropathy develops in approximately 5% to 8% of renal transplant recipients, and its prognosis is poor. The relationship between urine cytokines and BK viruria in kidney recipients has not been defined. PATIENTS AND METHODS: We compared posttransplant urine cytokine levels of 65 renal transplant outpatients with (BK-positive) or without BK viruria (BK-negative, n=33), low- (n=16) or high-level (n=16) BK viral load (VL), and 24 healthy controls (HCs). Soluble interleukin-1 receptor antagonist (sIL-1RA), interleukin (IL)-2, sIL-2R, IL-3, IL-4, IL-6, sIL-6R, IL-10, IL-17, transforming growth factor-beta2, interferon-gamma, and tumor necrosis factor-alpha levels were determined using commercially available ELISA kits. RESULTS: BK-positive patients showed higher urine IL-3 (P=0.006), sIL-6R (P=0.010), IL-6 (P=0.020), and sIL-1RA (P=0.050) than BK-negative patients. Compared with HCs, BK-negative patients had lower urine sIL-1RA (P=0.003), sIL-6R (P=0.001), and IL-17 (P<0.001), whereas BK-positive patients had higher urine IL-3 (P=0.004) and IL-6 (P=0.001) and lower IL-17 (P<0.001), suggesting cytokine suppression by immunosuppression and upregulation by BK-infection. Urine sIL-6R (P=0.003) and IL-6 (P=0.010) were higher in patients with high VL than in patients with low VL. Additionally, patients with high VL showed higher urine IL-6 (P=0.001), sIL-6R (P=0.001), sIL-1RA (P=0.016), and IL-3 (P=0.047) than BK-negative patients, and higher urine IL-6 (P<0.001) and lower IL-17 (P<0.001) than HCs. CONCLUSION: BK-positive renal transplant recipients, especially those with high VL, showed strong inflammatory cytokine responses with increases of urine sIL-1RA, IL-3, IL-6, and sIL-6R. Our data suggest that monocyte- and Th-2-induced cytokines are involved in the pathogenesis of BKV-associated nephropathy.

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.

Epidemiology of pretransplant EBV and CMV serostatus in relation to posttransplant non-Hodgkin lymphoma.

BACKGROUND.: Despite the importance of non-Hodgkin lymphoma (NHL) as a posttransplant complication, the relationship between NHL and recipient seropositivity for Epstein-Barr virus (EBV) or cytomegalovirus (CMV) is incompletely understood. METHODS.: Kidney, heart, and liver transplant recipients reported to the Collaborative Transplant Study with known pretransplant EBV and CMV serostatus were analyzed in terms of clinically manifest NHL. Cox multivariate regression analysis was performed to account for a wide range of possible confounders. RESULTS.: In total, 18,682 kidney, 2042 heart, and 2616 liver transplant recipients were analyzed. Regardless of age, pretransplant EBV serostatus was significantly associated with risk of NHL in kidney transplant recipients (P<0.001). There was no significant difference in lymphoma rates according to CMV and CMV serostatus among EBV and EBV recipients (log-rank P=0.55 and P=0.57, respectively), but hospitalization for CMV disease during year 1 posttransplant was associated with subsequent NHL (hazard ratio [HR] 6.1; 95% confidence interval [CI] 2.0-18.4; P=0.001). EBV serostatus was also associated with increased risk of NHL in heart transplant patients (HR 3.6; 95% CI 1.1-11.3; P=0.031) but, contrary to expectation, not in liver recipients (HR 0.6; 95% CI 0.1-1.7; P=0.32). CONCLUSIONS.: In view of the striking increase in risk of NHL in EBV kidney transplant recipients of all ages, EBV serostatus should be determined pretransplant in all age groups. CMV serostatus was not independently associated with risk of NHL after kidney transplantation. Surprisingly, in liver transplantation, the risk of NHL was virtually unaffected by EBV serostatus.

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.

Helenalin suppresses essential immune functions of activated CD4+ T cells by multiple mechanisms.

Helenalin is a naturally occuring sesquiterpene lactone extracted from Arnica montana and Arnica chamissonis ssp. foliosa. Helenalin and its derivatives are known for anti-cancer and anti-inflammatory effects via inhibiting NF-kappaB and telomerase activity and impairing protein and DNA synthesis, suggesting that helenalin is a potential candidate for the treatment of deregulated and unwanted T cell-mediated immune responses. Here we show that helenalin induces apoptosis in activated CD4+ T cells by triggering the mitochondrial pathway of apoptosis. Induction of apoptosis is accompanied by rapid stabilization of p53, nuclear localization of p53 and AIF, and an increase in ROS production that results in loss of mitochondrial membrane potential (DeltaPsim). Activated CD4+ T cells which survive exposure to helenalin undergo inhibition of proliferation by induction of G2/M cell cycle arrest. Cell cycle arrest is accompanied by the accumulation of cell cycle regulator proteins p21(WAF/CIP1), p2(KIP1) and cyclin D2, whereas abundance of cyclin A and B(1) is decreased. Cell surface expression of the activation-associated receptors CD25, CD27, CD28, CD120b as well as production of IL-2 are impaired. Transcriptional activation of genes encoding for CD25, IL-2 and IFN-gamma is mediated by transcription factors of the NFAT family, and we demonstrate that helenalin suppresses nuclear translocation of NFATc2 in activated CD4+ T cells. Thus, helenalin can be defined as a new immunosuppressive compound suited for the treatment of deregulated and unwanted T cell-mediated immune responses.

Association of pretransplant soluble glycoprotein 130 (sgp130) plasma levels and posttransplant acute tubular necrosis in renal transplant recipients.

OBJECTIVE: Previously, we reported that high pretransplant sIL-6R plasma levels are associated with posttransplant acute tubular necrosis (ATN). In this study, we examined associations of pretransplant plasma levels of sgp130 with ATN. PATIENTS AND METHODS: Pretransplant serum creatinine (Cr), plasma neopterin, and sgp130 levels were studied in 105 first renal transplant recipients who received grafts from deceased donors. Although 57 patients had immediate and sustained graft function, ATN was diagnosed in 30 patients within the first 11.3+/-7.8 posttransplant days and acute rejection in 18 patients during the first 27.1+/-27.6 days. RESULTS: Pretransplant serum Cr and plasma neopterin were similar in the three patient groups. Pretransplant sgp130 plasma levels, however, were significantly lower in patients with ATN than in patients with immediate graft function (P=0.004) or acute rejection (P=0.009). Multivariable logistic regression analysis for ATN showed an odds ratio of 4.3 of patients with pretransplant sgp130 less than or equal to 250 pg/mL with posttransplant ATN (P=0.006). CONCLUSION: Patients at risk of ATN showed immediately before transplantation low anti-inflammatory sgp130, suggesting a contribution of the IL-6 cytokine family to the development of ATN. It might be useful to measure IL-6 family plasma levels pretransplant to identify patients who are at an increased risk of developing ATN.

Role of ubiquitin ligases in neural stem and progenitor cells.

Ubiquitin ligases are central components of the ubiquitin-proteasome system (UPS), the major machinery for regulated proteolysis in eukaryotic cells. Proteins essential for regulating development, differentiation, proliferation, cell cycling, apoptosis, gene transcription, and signal transduction undergo posttranslational processing via selection by ubiquitin ligases and subsequent controlled proteolysis by the 26S proteasome, the proteolytic unit of the UPS. Neural stem cells (NSCs) are self-renewing multipotent cells of the embryonic and adult mammalian central nervous system. In the last few years, NSCs have generated considerable interest because of their potential to repair neurological damage in preclinical models of stroke, spinal cord injury, and neurodegenerative disease. Recent evidence reveals a central role of ubiquitin ligases in controlling the development, survival, differentiation, and programming of neural stem and progenitor cells. Here the current knowledge of the role and function of ubiquitin ligases in neural stem and progenitor cells is reviewed and insight into an important mechanism of NSC homeostasis by regulated proteolysis is provided.

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.