Maria C. Ochoa

Gene-gene interaction between PPAR gamma 2 and ADR beta 3 increases obesity risk in children and adolescents.

AIMS: Multiple genes are likely to be involved in obesity and these genes may interact with environmental factors to influence obesity risk. Our aim was to explore the synergistic contribution of the two polymorphisms: Pro12Ala of the PPARγ2 gene and Trp64Arg of the ADRβ3 gene to obesity risk in a Spanish children and adolescent population.METHODS: We designed a sex- and age-matched case–control study. Participants were 185 obese and 185 control children (aged 5–18 y) from the Navarra region, recruited through Departments of Pediatrics (Hospital Virgen del Camino, Navarra University Clinic and several Primary Health Centers). The obesity criterion (case definition) was BMI above the 97th percentile according to Spanish BMI reference data for age and gender. Anthropometric parameters were measured by standard protocols. The genotype was assessed by PCR-RFLP after digestion with BstUI for PPARγ2 mutation and BstNI for ADRβ3 variants. Face-to-face interviews were conducted to assess the physical activity. Using a validated physical activity questionnaire, we computed an activity metabolic equivalent index (METs h/week), which represents the physical exercise during the week for each participant. Statistical analysis was performed by conditional logistic regression, taking into account the matching between cases and controls.RESULTS: Carriers of the polymorphism Pro12Ala of the PPARγ2 gene had a significantly higher obesity risk than noncarriers (odds ratio (OR)=2.18, 95% CI=1.09–4.36) when we adjusted for sex, age and physical activity. Moreover, the risk of obesity was higher (OR=2.59, 95% CI=1.17–5.34) when family history of obesity was also taken into account in the model. The OR for obesity linked to both polymorphisms (PPARγ2 and ADRβ3) was 5.30 (95% CI=1.08–25.97) when we adjusted for sex, age and physical activity. After adjustment for family history of obesity, the OR for carriers of both polymorphisms was 19.5 (95% CI=2.43–146.8).CONCLUSIONS: A synergistic effect between polymorphism Pro12Ala of the PPARγ2 gene and Trp64Arg of the ADRβ3 gene for obesity risk was found in a case–control study including children and adolescents.

Therapeutic antitumor efficacy of anti-CD137 agonistic monoclonal antibody in mouse models of myeloma.

Purpose: Eradication of post-treatment residual myeloma cells is needed to prevent relapses, and immunostimulatory monoclonal antibodies (mAb) such as anti-CD137, CTLA-4, CD40, etc., which enhance the immune response against malignancies, represent a means of achieving this purpose. This study explores anti-CD137 mAbs for multiple myeloma treatment in preclinical models of the disease because they safely augment tumor immunity and are in clinical trials for other cancers. Experimental Design: The antitumor effect of anti-CD137 mAb on mouse plasmacytomas derived from HOPC and NS0 cell lines was studied and compared with that of anti-CTLA-4, anti-CD40, and anti-ICAM-2 mAbs. The antitumor effect of anti-CD137 mAb was also examined in a mouse syngeneic disseminated myeloma (5TGM1) model, which more closely resembles human multiple myeloma. Depletions of specific cell populations and gene-targeted mice were used to unravel the requirements for tumor rejection. Results: Agonistic mAb against CD137 and blocking anti-CTLA-4 mAb showed activity against i.p. HOPC tumors, resulting in extended survival of mice that also became immune to rechallenge. Anti-CD137 mAbs induced complete eradications of established s.c. NS0-derived tumors that were dependent on IFN-γ, natural killer cells, and CD8+ T lymphocytes. Natural killer cells accumulated in tumor draining lymph nodes and showed increased IFN-γ production. Antitumor efficacy of anti-CD137 mAb was preserved in CD28-deficient mice despite the fact that CD28 signaling increases the expression of CD137 on CD8+ T cells. Importantly, anti-CD137 mAb treatment significantly decreased systemic tumor burden in the disseminated 5TGM1 model. Conclusions: The immune-mediated antitumor activity of anti-CD137 mAb in mouse models holds promise for myeloma treatment in humans.

Treatment with anti-CD137 mAbs causes intense accumulations of liver T cells without selective antitumor immunotherapeutic effects in this organ

Background/aimsCancer therapy with agonist anti-CD137 mAbs has been shown to induce immune-mediated tumor rejections in mice, and equivalent agents of this kind are currently being tested in cancer patients. Previous reports indicated that CD137 stimulation induced polyclonal infiltrates of T lymphocytes in the liver. This study characterizes the liver infiltrates and the target dependency of the phenomena and addresses the question of whether tumors nested in the liver are a more favorable target for CD137-based immunotherapy.MethodsLiver infiltrates were studied with conventional histology and multiple color flow cytometry of total liver leukocytes. CD137−/− mice, mice with a single rearrangement of the TCR (OT-1 mice) and Rag−/− mice were used to clarify molecular requirements. Mice implanted with MC38 colon carcinomas either subcutaneously or inside the liver were used for comparative studies under treatment with agonist anti-CD137 mAbs.ResultsCD137 treatment caused mononuclear inflammation in the portal spaces of the liver, which gave rise to moderate increases in transaminases without signs of cholestasis. Marked increases in the numbers of CD8+ T cells were observed, including CD8+ T lymphocytes co-expressing CD11c. Infiltrates were absent in CD137−/− mice and mitigated in mice harboring a single transgenic TCR on their CD8 T cells. Despite the tumor-independent accumulation of T cells in the liver, immunotherapeutic effects were not more prominent against tumors located in this organ.ConclusionsTarget-dependent effects of CD137 stimulation lead to liver infiltration with T cells, but lymphocyte enrichment in this organ does not privilege this site for immunotherapeutic effects against transplanted tumors.

In vivo depletion of DC impairs the anti-tumor effect of agonistic anti-CD137 mAb

Anti‐CD137 mAb are capable of inducing tumor rejection in several syngeneic murine tumor models and are undergoing clinical trials for cancer. The anti‐tumor effect involves co‐stimulation of tumor‐specific CD8+ T cells. Whether antigen cross‐presenting DC are required for the efficacy of anti‐CD137 mAb treatment has never been examined. Here we show that the administration of anti‐CD137 mAb eradicates EG7‐OVA tumors by a strictly CD8β+ T‐cell‐dependent mechanism that correlates with increased CTL activity. Ex vivo analyses to determine the identity of the draining lymph node cell type responsible for tumor antigen cross‐presentation revealed that CD11c+ cells, most likely DC, are the main players in this tumor model. A minute number of tumor cells, revealed by the presence of OVA cDNA, reach tumor‐draining lymph nodes. Direct antigen presentation by tumor cells themselves also participates in anti‐OVA CTL induction. Using CD11c diphtheria toxin receptor‐green fluorescent protein→C57BL/6 BM chimeric mice, which allow for sustained ablation of DC with diphtheria toxin, we confirmed the involvement of DC in tumor antigen cross‐presentation in CTL induction against OVA257–264 epitope and in the antitumor efficacy induced by anti‐CD137 mAb.

Estudios sobre la obesidad en genes candidatos

Existen mas de 430 regiones cromosomicas que presentan variantes que podrian participar en la regulacion del peso corporal y en el desarrollo de obesidad. Los polimorfismos en genes relacionados con el gasto energetico como las proteinas desacoplantes, la adipogenia y/o resistencia a la insulina (receptores activados por el proliferador de peroxisomas gamma, los receptores betaadrenergicos, la lipasa sensible a hormonas y el factor de necrosis tumoral alfa) o el apetito (la grelina) parecen estar asociados a fenotipos de obesidad en diferentes poblaciones. El riesgo de ser obeso depende de: a) el repertorio de variaciones individuales en un conjunto de genes relevantes, y b) la historia de exposicion a factores de riesgo de tipo ambiental. Para obtener conclusiones relevantes, es necesario realizar estudios que incluyan a poblaciones control, tamano de muestra suficiente y disenos que ilustren la posible interaccion entre la genetica y el ambiente (dieta, estilo de vida)

Targeting NK-cell checkpoints for cancer immunotherapy.

Natural Killer (NK) cells are cytotoxic lymphocytes specialized in early defense against virus-infected and transformed cells. NK-cell function is regulated by activating and inhibitory surface receptors recognizing their ligands on transformed cells. Modulation of NK numbers and/or function by a variety of agents such as cytokines and monoclonal antibodies may result in enhanced anti-tumor activity. Recombinant cytokines (i.e., IL-15 and IL-2), antibodies blocking inhibitory receptors (i.e., KIR, NKG2A and TIGIT) and agonists delivering signals via CD137, NKG2D and CD16 stand out as the most suitable opportunities. These agents can be used to potentiate NKcell- mediated antibody-dependent cellular cytotoxicity (ADCC) against antibody-coated tumor cells, offering potential for multiple combinatorial immunotherapy strategies against cancer.

Intratumoral injection of interferon‐α and systemic delivery of agonist anti‐CD137 monoclonal antibodies synergize for immunotherapy

CD137 artificial costimulation results in complete tumor rejection in several mouse models. Type I interferons (IFN) exert antitumor effects through an array of molecular functions on malignant cells, tumor stroma and immune system cells. The fact that agonist anti‐CD137 mAb induce tumor regressions in mice deficient in the unique receptor for Type I IFNs (IFNAR−/−) indicated potential for treatment combinations. Indeed, combination of intratumor injections of mouse IFN‐α and intraperitoneal injections of anti‐CD137 mAb synergized as seen on subcutaneous lesions derived from the MC38 colon carcinoma, which is resistant to each treatment if given separately. Therapeutic activity was achieved both against lesions directly injected with IFN‐α and against distant concomitant tumors. Experiments in bone marrow chimeras prepared with IFNAR−/− and WT mice concluded that expression of the receptor for Type I interferons is mainly required on cells of the hematopoietic compartment. Synergistic effects correlated with a remarkable cellular hyperplasia of the tumor draining lymph nodes (TDLNs). Enlarged TDLNs contained more plasmacytoid and conventional dendritic cells (DC) that more readily cross‐presented. Importantly, numbers of both DC subtypes inversely correlated with the tumor size. Numbers of CD8 T cells specific for a dominant tumor antigen were increased at TDLNs by each separate treatment but only with slight augments due to the combination. Combined antitumor effects of the therapeutic strategy were also seen on subcutaneous TC‐1 tumors established for 24 days before treatment onset. The described strategy is realistic because (i) agents of each kind are clinically available and (ii) equivalent procedures in humans are feasible.

Treatment of obesity in children and adolescents. How nutrition can work

Overweight appears when persistent positive energy imbalances occur for long periods of time. Knowledge of dietary risk factors during childhood and adolescence is needed in order to design preventive measures against the increase in the prevalence of obesity and its consequences but is, however, largely missing. Longitudinal studies in children have not found clear causal associations between energy intake or diet composition and overweight development. Research has been ongoing to develop effective intervention studies for obese children but it is not clear which intervention is the most effective in assisting overweight/obese children to improve body composition without affecting growth rates. The objective of this article is to review the available knowledge on dietary risk factors for the development of childhood obesity, to discuss different dietary treatment strategies, and to propose an evidence-based approach to treat obese adolescents.

Dietary total antioxidant capacity and obesity in children and adolescents

Background Dietary antioxidant intake has been suggested to protect against oxidative damage and related clinical complications. The aim of the present study was to assess the potential relationships between the dietary total antioxidant capacity (TAC) and obesity-related features in children and adolescents. Materials and methods Anthropometric variables from 369 children and adolescents were measured (184 obese and 185 control). A validated food-frequency questionnaire was used to calculate the TAC and the daily nutrient and energy intake. Results Dietary TAC showed positive associations with fiber, folic acid, magnesium, and vitamins A, C and E. The body mass index, standard deviation score of body mass index and total body fat were inversely associated with dietary TAC only in obese subjects. Conclusion These data suggest that dietary TAC may be a potential indicator of the risk to develop obesity-related features and could be considered a useful method in assessing antioxidant intake.

Antibody-dependent cell cytotoxicity: immunotherapy strategies enhancing effector NK cells

Antibody‐dependent cellular cytotoxicity (ADCC) is a set of mechanisms that target cells coated with IgG antibodies of the proper subclasses (IgG1 in the human) to be the prey of cell‐to‐cell cytolysis executed by immune cells expressing FcRIIIA (CD16A). These effectors include not only natural killer (NK) cells but also other CD16+ subsets such as monocyte/macrophages, NKT cells or γδ T cells. In cancer therapy, ADCC is exploited by antibodies that selectively recognize proteins on the surface of malignant cells. An approach to enhance antitumor activity is to act on effector cells so they are increased in their numbers or enhanced in their individual (on a cell per cell basis) ADCC performance. This enhancement can be therapeutically attained by cytokines (that is, interleukin (IL)‐15, IL‐21, IL‐18, IL‐2); immunostimulatory monoclonal antibodies (that is, anti‐CD137, anti‐CD96, anti‐TIGIT, anti‐KIR, anti‐PD‐1); TLR agonists or by adoptive infusions of ex vivo expanded NK cells which can be genetically engineered to become more efficient effectors. In conjunction with approaches optimizing IgG1 Fc affinity to CD16, acting on effector cells offers hope to achieve synergistic immunotherapy strategies.