Lilia Goudeva

Short-term and long-term leptin exposure differentially affect human natural killer cell immune functions

Epidemiological studies have indicated that obesity is associated with a higher risk for certain cancers caused by elevated levels of adipocyte-derived hormones. Leptin, one such hormone produced by adipocytes, is a major regulator of metabolism and has also been shown to modulate immunity. However, its role in regulating human natural killer (NK) cell functions is largely unknown. Here, we show that the leptin receptor (Ob-R) is expressed on 5% of NK cells isolated from blood donors, as measured with flow cytometry, and expression of the signal-transducing long form of the leptin receptor Ob-Rb was confirmed with quantitative PCR. The Ob-R+ subpopulation displayed a lower expression of CD16, a cell surface receptor mediating antibody-dependent activation. Short-term stimulation with leptin increased IFNγ secretion, CD69 activation marker expression, and cytotoxic lysis of tumor cells; this was mediated by an improved conjugate forming between NK cells and tumor cells as well as higher expression of tumor necrosis factor-related apoptosis-inducing ligand. On the contrary, long-term incubation with leptin significantly impaired these NK cell immune functions and decreased cell proliferation. In addition, phosphorylation of Jak-2 after leptin stimulation was reduced in peripheral mononuclear blood cells from obese humans compared with normal-weight controls. NK cells represent an immune cell population that is crucial for an effective antitumor response. Here, we show that long-term exposure to leptin, similarly to the situation in obese individuals with elevated serum leptin levels, significantly impairs integral parts of NK cell immune functions, possibly linking leptin to increased cancer susceptibility in obesity.

Obesity and the risk of papillary thyroid cancer: a pooled analysis of three case-control studies.

BACKGROUND There is a correlation between temporal trends of obesity prevalence and papillary thyroid cancer (PTC) incidence in the United States. Obesity is a well-recognized risk factor for many cancers, but there are few studies on the association between obesity and PTC risk. We investigated the association between anthropometric measurements and PTC risk using pooled individual data from three case-control populations. METHODS Height and weight information were obtained from three independent case-control studies, including 1917 patients with PTC (1360 women and 557 men) and 2127 cancer-free controls from the United States, Italy, and Germany. Body mass index (BMI), body fat percentage, and body surface area (BSA) were calculated. An unconditional logistic regression model was used to calculate odds ratios (ORs) and confidence intervals (CIs) with respect to risk of PTC, adjusted by age, sex, race/ethnicity, and study site. RESULTS In the pooled population, for both men and women, an increased risk of PTC was found to be associated with greater weight, BMI, body fat percentage, and BSA, whereas a reduced risk of PTC was associated with greater height, in the pooled population for both men and women. Compared with normal-weight subjects (BMI 18.5-24.9 kg/m2), the ORs for overweight (BMI 25-29.9 kg/m2) and obese (BMI≥30 kg/m2) subjects were 1.72 [CI 1.48-2.00] and 4.17 [CI 3.41-5.10] respectively. Compared with the lowest quartile of body fat percentage, the ORs for the highest quartile were 3.83 [CI 2.85-5.15] in women and 4.05 [CI 2.67-6.15] in men. CONCLUSION Anthropometric factors, especially BMI and body fat percentage, were significantly associated with increased risk of PTC. Future studies of anthropometric factors and PTC that incorporate intermediate factors, including adiposity and hormone biomarkers, are essential to help clarify potential mechanisms of the relationship.

Generation of HLA-deficient platelets from hematopoietic progenitor cells.

BACKGROUND: Exposure to allogeneic blood products often leads to the development of human leukocyte antigen (HLA) antibodies. Refractoriness to platelet (PLT) transfusion caused by alloimmunization against HLA Class I antigens constitutes a significant clinical problem.

Human regulatory T cells of G-CSF mobilized allogeneic stem cell donors qualify for clinical application.

Recent clinical studies demonstrate the high potency of regulatory T cells (Tregs) to control graft-versus-host disease in hematopoietic stem cell transplantation (SCT). However, the adoptive transfer of Tregs is limited by their low frequency in unstimulated donors and considerable concerns that G-CSF induced SC mobilization might have negative effects on the stability and function of Tregs. The isolation of Tregs from the G-CSF mobilized SC grafts would extend this novel strategy for tolerance induction to the unrelated setting and simplify global clinical application. We characterized CD4+CD25highCD127− Tregs from SC donors before and after G-CSF mobilization for their phenotype, function, and stability. After G-CSF application the Treg cell yield increased significantly. Donor Tregs retained their cytokine profile, phenotypic characteristics and in vitro expansion capacity after SC mobilization. Most importantly, in vivo G-CSF stimulated Tregs remained highly suppressive on the proliferation of effector T cells, also after in vitro expansion, and displayed a stable phenotype in epigenetic studies. The surface expression of CXCR3 is transiently reduced. However, donor-derived Tregs maintain their migratory properties after G-CSF stimulation. Therefore, the adoptive transfer of Tregs from G-CSF mobilized SC donors seems to be a feasible and safe strategy for clinical application in allogeneic SCT.

Equivalent mobilization and collection of granulocytes for transfusion after administration of glycosylated G–CSF (3 μg/kg) plus dexamethasone versus glycosylated G–CSF (12 μg/kg) alone

BACKGROUND: The aim of this study was to find a regimen for mobilization and collection of granulocytes that combines low‐dose G–CSF administration with satisfactory PMN mobilization and apheresis at a low rate of donor adverse reactions.

Human NK Cell Subset Functions Are Differentially Affected by Adipokines

Background Obesity is a risk factor for various types of infectious diseases and cancer. The increase in adipose tissue causes alterations in both adipogenesis and the production of adipocyte-secreted proteins (adipokines). Since natural killer (NK) cells are the host’s primary defense against virus-infected and tumor cells, we investigated how adipocyte-conditioned medium (ACM) affects functions of two distinct human NK cell subsets. Methods Isolated human peripheral blood mononuclear cells (PBMCs) were cultured with various concentrations of human and murine ACM harvested on two different days during adipogenesis and analyzed by fluorescent-activated cell sorting (FACS). Results FACS analyses showed that the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), granzyme A (GzmA) and interferon (IFN)-γ in NK cells was regulated in a subset-specific manner. ACM treatment altered IFN-γ expression in CD56dim NK cells. The production of GzmA in CD56bright NK cells was differentially affected by the distinct adipokine compositions harvested at different states of adipogenesis. Comparison of the treatment with either human or murine ACM revealed that adipokine-induced effects on NK cell expression of the leptin receptor (Ob-R), TRAIL and IFN-γ were species-specific. Conclusion Considering the growing prevalence of obesity and the various disorders related to it, the present study provides further insights into the roles human NK cell subsets play in the obesity-associated state of chronic low-grade inflammation.

Impaired Functionality of Antiviral T Cells in G-CSF Mobilized Stem Cell Donors: Implications for the Selection of CTL Donor

Adoptive transfer of antiviral T cells enhances immune reconstitution and decreases infectious complications after stem cell transplantation. Information on number and function of antiviral T cells in stem cell grafts is scarce. We investigated (1) immunomodulatory effects of G-CSF on antiviral T cells, (2) the influence of apheresis, and (3) the optimal time point to collect antiviral cells. CMV-, EBV- and ADV-specific T cells were enumerated in 170 G-CSF-mobilized stem cell and 24 non-mobilized platelet donors using 14 HLA-matched multimers. T-cell function was evaluated by IFN-γ ELISpot and granzyme B secretion. Immunophenotyping was performed by multicolor flow cytometry. G-CSF treatment did not significantly influence frequency of antiviral T cells nor their in vitro expansion rate upon antigen restimulation. However, T-cell function was significantly impaired, as expressed by a mean reduction in secretion of IFN-γ (75% in vivo, 40% in vitro) and granzyme B (32% target-independent, 76% target-dependent) as well as CD107a expression (27%). Clinical follow up data indicate that the first CMV-reactivation in patients and with it the need for T-cell transfer occurs while the donor is still under the influence of G-CSF. To overcome these limitations, T-cell banking before mobilization or recruitment of third party donors might be an option to optimize T-cell production.

Desmopressin (DDAVP) improves recruitment of activated platelets to collagen but simultaneously increases platelet endothelial interactions in vitro

Platelet dysfunction can cause clinically relevant bleeding. Treatment with DDAVP is advocated for this condition. DDAVP increases von Willebrand factor (VWF) on endothelial cells (ECs) and in plasma. VWF could facilitate platelet deposition on subendothelial collagen. VWF also facilitates platelet/EC interactions. Therefore DDAVP could precipitate thromboembolic events. We used a flow chamber model to study in vitro and ex vivo if DDAVP alters recruitment of platelets to EC and collagen. Resting or TRAP-activated platelets and EC were treated individually or simultaneously with 0.4 ng/ml DDAVP. Fluorophor-labeled platelets (106/ml) were resuspended in reconstituted blood and superfused across EC and collagen in an in vitro flow chamber model at arterial shear (320 s−1). Adhesion of platelets to the respective surface was recorded fluorescence microscopically and platelet covered area was assessed. TRAP significantly induced adhesiveness of platelets for collagen and EC. DDAVP pretreatment of platelets did not affect adhesiveness of resting or TRAP-activated platelets for collagen or EC. Adhesiveness of resting but not TRAP-activated platelets was induced on DDAVP-treated EC. DDAVP-conditioned EC supernatant contained vWF and significantly increased platelet deposition on collagen. Platelets from patients with clinically suspected platelet dysfunction undergoing aortic valve replacement exhibited decreased platelet deposition on collagen surfaces. In summary, our data confirm that DDAVP can induce release of platelet adhesion promoting factors from EC, which is most likely vWF. DDAVP has no direct effect on platelets. Blood samples from DDAVP-treated patients do not exhibit significantly augmented platelet deposition on collagen ex vivo. This influence of released promoting factors might cause an increase of undesirable interactions of platelets with EC.

A dose‐response analysis of lenograstim plus dexamethasone for neutrophil mobilization and collection

BACKGROUND: The objective was to evaluate the dose‐response relationship of lenograstim plus dexamethasone for neutrophil mobilization and collection.

Low platelet counts after induction therapy for childhood acute lymphoblastic leukemia are strongly associated with poor early response to treatment as measured by minimal residual disease and are prognostic for treatment outcome

Background Numerous reports have been published on the association between kinetics of leukemic cells during early treatment of childhood acute lymphoblastic leukemia and therapeutic outcome. In contrast, little is known about the prognostic relevance of normal blood counts in this setting. Design and Methods Normal hematopoiesis during and after induction treatment (days 8, 15 and 33) was correlated with therapeutic outcome in a cohort of 256 children with acute lymphoblastic leukemia treated in one of three consecutive ALL-BFM trials at a single institute. Replication analysis of positive findings was performed in an independent cohort of 475 patients from the ALL-BFM 2000 multicenter trial. Results A platelet count in the first quartile on treatment day 33 and a neutrophil count above the median on day 8 were significantly associated with treatment outcome, conferring multivariate risk ratios for an event of 3.27 (95% confidence interval 1.60–6.69) and 2.26 (95% confidence interval 1.23–4.29), respectively. Replication analysis confirmed the prognostic effect of platelet count on treatment day 33 and demonstrated a strong association with minimal residual disease-based risk group distribution (P<0.00001). Conclusions Platelet counts after induction treatment may improve treatment stratification for patients with childhood acute lymphoblastic leukemia and be of particular interest in non-minimal residual disease-based trials. (ALL-BFM 2000 is registered at: ClinicalTrials.gov: NCT00430118. National Cancer Institute: Protocol ID 68529)