The role of SIRT6 protein in aging and reprogramming of human induced pluripotent stem cells

Aging is known to be the single most important risk factor for multiple diseases. Sirtuin 6, or SIRT6, has recently been identified as a critical regulator of transcription, genome stability, telomere integrity, DNA repair, and metabolic homeostasis. A knockout mouse model of SIRT6 has displayed dramatic phenotypes of accelerated aging. In keeping with its role in aging, we demonstrated that human dermal fibroblasts (HDFs) from older human subjects were more resistant to reprogramming by classic Yamanaka factors than those from younger human subjects, but the addition of SIRT6 during reprogramming improved such efficiency in older HDFs substantially. Despite the importance of SIRT6, little is known about the molecular mechanism of its regulation. We show, for the first, time posttranscriptional regulation of SIRT6 by miR-766 and inverse correlation in the expression of this microRNA in HDFs from different age groups. Our results suggest that SIRT6 regulates miR-766 transcription via a feedback regulatory loop, which has implications for the modulation of SIRT6 expression in reprogramming of aging cells

Endothelial dysfunction in pregnancy metabolic disorders

In recent years, the vascular endothelium has gained attention as a key player in the initiation and development of pregnancy disorders. Endothelium acts as an endocrine organ that preserves the homeostatic balance by responding to changes in metabolic status. However, in metabolic disorders, endothelial cells adopt a dysfunctional function, losing their normal responsiveness. During pregnancy, several metabolic changes occur, in which endothelial function decisively participates. Similarly, when pregnancy metabolic disorders occur, endothelial dysfunction plays a key role in pathogenesis. This review outlines the main findings regarding endothelial dysfunction in three main metabolic pathological conditions observed during pregnancy: gestational diabetes, hypertensive disorders, and obesity and hyperlipidemia. Organ, histological and cellular characteristics were thoroughly described. Also, we focused in discussing the underlying molecular mechanisms involved in the cellular signaling pathways that mediate responses in these pathological conditions

The peptide angiotensin-(1-7) as a novel treatment for complications induced by type 2 diabetes mellitus

The aim of this dissertation is to evaluate the impact of type 2 diabetes mellitus on oxidative stress and inflammation in the bone marrow and circulation, as well as investigate the relationship between these molecular alterations and long-term complications of diabetes, specifically cardiovascular disease. In addition, the role of the peptide Ang-(1-7) i as well as the receptor and second messager systems involved in reversing these molecular alterations and complications will also be determined. The research integrates multiple in vivo studies and a clinical study to provide a comprehensive picture of this disease state. Nitrite levels in the bone marrow and blood were measured using the Griess reaction. Expression and protein levels of molecular markers of oxidative stress and cytokines were determined using RT-PCR, western blot, and ELISA. Levels of oxidative stress, protein tyrosine nitration in the bone marrow, intracellular cytokine levels, and EPC counts were measured using flow cytometric methodologies. Tissue protein nitration was measured by immunohistochemistry. Murine heart function was determined in vivo using small animal echocardiography and thermodilution techniques, and histology was used to measure cardiomyocytes in stained heart sections. Culture of isolated bone marrow cells was used to determine various progenitor counts. Our in vivo and clinical data indicate that oxidative stress and systemic inflammation play a major role in both type 2 diabetes and gestational diabetes. In addition, we illustrate a potential link between these pathologies and endothelial and cardiovascular dysfunction in this disease state. Treatment of db/db mice with Ang-(1-7) for 14 days resulted in decreases in markers of oxidative stress and inflammation, increases in bone marrow-derived and circulating EPC, as well as increases in other bone marrow-derived progenitors involved in vasculogenesis and immune function. Lastly, Ang-(1-7) treatment helped to increase measures of cardiac function that were reduced in diabetic mice. While a focus on glucose control is still of the utmost importance, more attention needs to be spent on reversing the pre-existing cellular damage caused by oxidative stress and inflammation in diabetes. Ang-(1-7) may be one of multiple promising agents with the ability to work synergistically with currently FDA-approved therapies; together able to reduce plasma glucose levels, preventing further damage, and reverse oxidative stress and inflammation in type 2 diabetes. Combined, this therapeutic strategy could potentially significantly reduce the risk of some of the long-term and deadly complications of diabetes, including cardiovascular disease

Can Therapeutic Drug Monitoring Improve Pharmacotherapy of HIV Infection in Adolescents?

Currently, therapeutic drug monitoring (TDM) of antiretroviral therapy (ART) is not performed in the United States as part of routine clinical care of an HIV-infected adolescent patient. TDM is recommended to rule out subtherapeutic drug concentrations and to differentiate among malabsorption, drug interactions, poor adherence, or increased drug metabolism or clearance as possible causes of decreased drug exposure. The use of TDM is also considered to assist in finding the optimal dose of a drug in patients whose virus has shown reduced susceptibility to that drug. The dosing of antiretroviral (ARV) drugs in adolescent patients with HIV infection depends on the chronologic age, weight, height, and the stage of sexual maturation. As a result of the limited data on the pharmacokinetics of ART during puberty, the transition of a dosing regimen from higher pediatric (weight and surface-based) to adult (fixed) range is not well defined. Developmental pharmacokinetic differences contribute to high variability in pediatric and adolescent patients and an increased frequency of suboptimal ARV exposure as compared to in adults. Individualized, concentration- targeted optimal dosing of ARV medications can be beneficial to patients for whom only limited dosing guidelines are available. This article describes three cases of the application of TDM in treatment-experienced adolescent patients whose ART was optimized using ARV TDM. TDM of ARV drugs is useful in managing the pharmacotherapy of HIV in adolescent patients and is well received by the adolescent patients with HIV and their families. Among others, the benefits of TDM provide evidence for adherence interventions and create grounds for enhanced education of the adolescent patient and involved adult caregivers about ART. Finally, TDM in adolescents provides valuable information about the clinical pharmacology of ART during puberty

Can therapeutic drug monitoring improve pharmacotherapy of hiv infection in adolescents?

Currently, therapeutic drug monitoring (TDM) of antiretroviral therapy (ART) is not performed in the US as part of routine clinical care of an HIV-infected adolescent patient. TDM is recommended to rule out subtherapeutic drug concentrations and to differentiate between malabsorption, drug interactions, poor adherence, or increased drug metabolism or clearance as possible causes of decreased drug exposure. The use of TDM is also considered to assist in finding the optimal dose of a drug in patients in patients whose virus has shown a reduced susceptibility to that drug. The dosing of antiretroviral (ARV) drugs in adolescent patients with HIV infection depends on the chronological age, weight, height and the stage of sexual maturation. Due to the limited data on the pharmacokinetics (PK) of ART during puberty the transition of a dosing regimen from higher pediatric (weight and surface-based) to adult (fixed) range is not well defined. Developmental PK differences contribute to high variability in pediatric and adolescent patients and an increased frequency of suboptimal ARV exposure than in adults. Individualized, concentration-targeted optimal dosing of ARV medications can be beneficial to patients for whom only limited dosing guidelines are available. This manuscript describes 3 cases of the application of TDM in treatment experienced adolescent patients whose ART was optimized using of ARV TDM. TDM of ARV drugs is useful in managing the pharmacotherapy of HIV in adolescent patients and is well received by the adolescent patients with HIV and their families. Among others, the benefits of TDM provide evidence for adherence interventions and create grounds for enhanced education of the adolescent patient and involved adult caregivers about ART. Finally, TDM in adolescents provides valuable information about the clinical pharmacology of ART during puberty

Interleukin-1 as an injury signal mobilizes retinyl esters in hepatic stellate cells through down regulation of lecithin retinol acyltransferase.

Retinoids are mostly stored as retinyl esters in hepatic stellate cells (HSCs) through esterification of retinol and fatty acid, catalyzed by lecithin-retinol acyltransferase (LRAT). This study is designated to address how retinyl esters are mobilized in liver injury for tissue repair and wound healing. Initially, we speculated that acute inflammatory cytokines may act as injury signal to mobilize retinyl esters by down-regulation of LRAT in HSCs. By examining a panel of cytokines we found interleukin-1 (IL-1) can potently down-regulate mRNA and protein levels of LRAT, resulting in mobilization of retinyl esters in primary rat HSCs. To simulate the microenvironment in the space of Disse, HSCs were embedded in three-dimensional extracellular matrix, by which HSCs retaine quiescent phenotypes, indicated by up-regulation of LRAT and accumulation of lipid droplets. Upon IL-1 stimulation, LRAT expression went down together with mobilization of lipid droplets. Secreted factors from Kupffer cells were able to suppress LRAT expression in HSCs, which was neutralized by IL-1 receptor antagonist. To explore the underlying mechanism we noted that the stability of LRAT protein is not significantly regulated by IL-1, indicating the regulation is likely at transcriptional level. Indeed, we found that IL-1 failed to down-regulate recombinant LRAT protein expressed in HSCs by adenovirus, while transcription of endogenous LRAT was promptly decreased. Following liver damage, IL-1 was promptly elevated in a close pace with down-regulation of LRAT transcription, implying their causative relationship. After administration of IL-1, retinyl ester levels in the liver, as measured by LC/MS/MS, decreased in association with down-regulation of LRAT. Likewise, IL-1 receptor knockout mice were protected from injury-induced down-regulation of LRAT. In summary, we identified IL-1 as an injury signal to mobilize retinyl ester in HSCs through down-regulation of LRAT, implying a mechanism governing transition from hepatic injury to wound healing