Functional analysis of TCF7L2 genetic variants associated with type 2 diabetes

BACKGROUND AND AIMS

Common non-coding variations within the TCF7L2 locus have a strong influence on type 2 diabetes (T2D) susceptibility through uncharacterised mechanisms. An islet-specific functional polymorphism has been identified, although this does not explain the association between genotype and gene expression in other cell types. This study sought to identify these other functional TCF7L2 variants.

METHODS AND RESULTS

Alternative splicing and gene expression from TCF7L2 was examined from peripheral blood mononuclear cells from 100 healthy Caucasians using two T2D-associated SNPs, rs7903146 and rs12255372. Electrophoretic mobility shift assays and luciferase reporter assays were performed with these SNPs and those in strong LD to determine potential SNP functionality. Individuals homozygous for rs7903146 and rs12255372 T2D risk alleles (TT/TT) expressed 2.6-fold greater levels of TCF7L2 mRNA compared to individuals homozygous for the non-risk alleles (CC/GG, p = 0.006), although differentially spliced TCF7L2 transcripts did not differ by T2D risk-associated genotype. From SNPs identified to be in strong LD with the T2D-associated SNPs, rs7903146 and rs12255372, five (rs4132670, rs4506565, rs7903146, rs7901695, rs17747324) demonstrated allele-specific binding in electrophoretic mobility shift assays (EMSA). In luciferase reporter assays, rs4132670 exhibited 1.3-fold higher levels of enhancer activity in the Huh7 cell line (p = 3.8 × 10(-5)) and 2-fold higher levels in a WiDr colon carcinoma cell line (p = 0.008).

CONCLUSIONS

These results suggest that rs4132670, located in a region of chromatin accessibility, is a non-tissue-specific candidate functional SNP that has the potential to play a role in TCF7L2 gene expression and T2D risk.

Hepatitis C virus-specific cell-mediated immune responses in children born to mothers infected with hepatitis C virus

OBJECTIVE

To investigate the association between hepatitis C virus (HCV)-specific cell-mediated immunity (CMI) responses and viral clearance in children born to mothers infected with HCV.

STUDY DESIGN

A cross-sectional study of children from a mother-infant cohort in Egypt were enrolled to detect CMI responses to recombinant core and nonstructural HCV antigens (nonstructural segments NS3, NS4a/b, and NS5 of the HCV genome) using an interferon-gamma enzyme-linked immunospot assay. Children born to mothers with chronic HCV were enrolled into 3 groups: transiently viremic (n = 5), aviremic (n = 36), and positive control (n = 6), which consisted of 1 child with chronic HCV from this cohort and another 5 children with chronic HCV from a companion study. Children without HCV born to mothers without HCV (n = 27) served as a negative control group. Wilcoxon rank sum test was used to compare the magnitude of CMI responses between groups.

RESULTS

None of the 6 control children who were positive for HCV responded to any HCV antigen, and 4 (80%) of 5 children with transient viremia responded to at least one HCV antigen, compared with 5 (14%) of 36 and 3 (11%) of 27 children in the aviremic and negative control groups, respectively. Children with transient viremia elicited stronger responses than did negative controls (P = .005), positive controls (P = .011), or children without HCV viremia (P = .012), particularly to nonstructural antigens.

CONCLUSIONS

HCV-specific CMI responses were significantly higher in magnitude and frequency among transiently infected children compared with those persistently infected. This suggests CMI responses may be associated with past viral clearance and can identify children at high risk of infection, who can be targeted for health education, screening, and follow-up.

Translational research in infectious disease: current paradigms and challenges ahead

In recent years, the biomedical community has witnessed a rapid scientific and technologic evolution after the development and refinement of high-throughput methodologies. Concurrently and consequentially, the scientific perspective has changed from the reductionist approach of meticulously analyzing the fine details of a single component of biology to the "holistic" approach of broadmindedly examining the globally interacting elements of biological systems. The emergence of this new way of thinking has brought about a scientific revolution in which genomics, proteomics, metabolomics, and other "omics" have become the predominant tools by which large amounts of data are amassed, analyzed, and applied to complex questions of biology that were previously unsolvable. This enormous transformation of basic science research and the ensuing plethora of promising data, especially in the realm of human health and disease, have unfortunately not been followed by a parallel increase in the clinical application of this information. On the contrary, the number of new potential drugs in development has been decreasing steadily, suggesting the existence of roadblocks that prevent the translation of promising research into medically relevant therapeutic or diagnostic application. In this article, we will review, in a noninclusive fashion, several recent scientific advancements in the field of translational research, with a specific focus on how they relate to infectious disease. We will also present a current picture of the limitations and challenges that exist for translational research, as well as ways that have been proposed by the National Institutes of Health to improve the state of this field.

Liver sinusoidal endothelial cell lectin, LSECtin, negatively regulates hepatic T-cell immune response

BACKGROUND & AIMS

The liver is an organ with paradoxic immunologic properties and is known for its tolerant microenvironment, which holds important implications for hepatic diseases. The molecular basis for this local immune suppression, however, is poorly understood. In this study, we aimed to determine the role of liver sinusoidal endothelial cell lectin (LSECtin), a recently identified member of the dendritic cell-specific ICAM-3 grabbing nonintegrin (DC-SIGN) family, in the regulation of hepatic T-cell immune response.

METHODS

The regulation of T-cell effector function by LSECtin was determined by co-stimulated T cells with anti-CD3/CD28 monoclonal antibody and LSECtin protein, or co-culture of T-cell receptor transgenic T cells with mouse LSECs in vitro. We generated LSECtin knockout mice and prepared recombinant LSECtin protein and complementary DNA plasmids to analyze the role of LSECtin in hepatic T-cell immune regulation in vivo.

RESULTS

We showed that LSECtin specifically recognized activated T cells and negatively regulated their immune responses. In mice with T-cell-mediated acute liver injury, the lack of LSECtin accelerated the disease owing to an increased T-cell immune response, whereas the exogenous administration of recombinant LSECtin protein or plasmid ameliorated the disease via down-regulation of T-cell immunity.

CONCLUSIONS

Our results reveal that LSECtin is a novel regulator of T cells and expose a crucial mechanism for hepatic T-cell immune suppression, perhaps opening up a new approach for treatment of inflammatory diseases in the liver.

Rhinosinusitis: establishing definitions for clinical research and patient care

Background

There is a need for more research on all forms of rhinosinusitis. Progress in this area has been hampered by a lack of consensus definitions and the limited number of published clinical trials.

Objectives

To develop consensus definitions for rhinosinusitis and outline strategies useful in clinical trials.

Methods

Five national societies, The American Academy of Allergy, Asthma and Immunology; The American Academy of Otolaryngic Allergy; The American Academy of Otolaryngology Head and Neck Surgery; The American College of Allergy, Asthma and Immunology; and the American Rhinologic Society formed an expert panel from multiple disciplines. Over two days, the panel developed definitions for rhinosinusitis and outlined strategies for design of clinical trials.

Results

Committee members agreed to adopt the term “rhinosinusitis” and reached consensus on definitions and strategies for clinical research on acute presumed bacterial rhinosinusitis, chronic rhinosinusitis without polyposis, chronic rhinosinusitis with polyposis, and classic allergic fungal rhinosinusitis. Symptom and objective criteria, measures for monitoring research progress, and use of symptom scoring tools, quality-of-life instruments, radiologic studies, and rhinoscopic assessment were outlined for each condition.

Conclusion

The recommendations from this conference should improve accuracy of clinical diagnosis and serve as a starting point for design of rhinosinusitis clinical trials.