Use of an oral stable isotope label to confirm variation in red blood cell mean age that influences HbA1c interpretation.

HbA1c is commonly used to monitor glycemic control. However, there is growing evidence that the relationship between HbA1c and mean blood glucose (MBG) is influenced by variation in red blood cell (RBC) lifespan in hematologically normal individuals. Correction of HbA1c for mean RBC age (MRBC ) requires a noninvasive, accurate, and affordable method to measure RBC survival. In this study, we evaluated whether a stable isotope approach would satisfy these requirements. RBC lifespan and MRBC were determined in a group of nine hematologically normal diabetic and nondiabetic subjects using oral (15) N-glycine to label heme in an age cohort of RBC. The MRBC was 58.7 ± 9.1 (2SD) days and RBC lifespan was 106 ± 21 (2SD) days. This degree of variation (±15-20%) is consistent with previous studies using other techniques. In a subset of seven subjects, MRBC determined with the biotin label technique were available from approximately five years prior, and strongly correlated with the stable isotope values (R(2) = 0.79). This study suggests that the MRBC is stable over time but varies substantially among individuals, and supports the importance of its variation in HbA1c interpretation. The characteristics of the stable isotope method support its suitability for studies to directly evaluate the impact of variation in MRBC on the interpretation of HbA1c.

Genetic analysis of interferon induced thyroiditis (IIT): evidence for a key role for MHC and apoptosis related genes and pathways.

Autoimmune thyroid diseases (AITD) have become increasingly recognized as a complication of interferon-alpha (IFNα) therapy in patients with chronic Hepatitis C virus (HCV) infection. Interferon-induced thyroiditis (IIT) can manifest as clinical thyroiditis in approximately 15% of HCV patients receiving IFNα and subclinical thyroiditis in up to 40% of patients, possibly resulting in either dose reduction or discontinuation of IFNα treatment. However, the exact mechanisms that lead to the development of IIT are unknown and may include IFNα-mediated immune-recruitment as well as direct toxic effects on thyroid follicular cells. We hypothesized that IIT develops in genetically predisposed individuals whose threshold for developing thyroiditis is lowered by IFNα. Therefore, our aim was to identify the susceptibility genes for IIT. We used a genomic convergence approach combining genetic association data with transcriptome analysis of genes upregulated by IFNα. Integrating results of genetic association, transcriptome data, pathway, and haplotype analyses enabled the identification of 3 putative loci, SP100/110/140 (2q37.1), HLA (6p21.3), and TAP1 (6p21.3) that may be involved in the pathogenesis of IIT. Immune-regulation and apoptosis emerged as the predominant mechanisms underlying the etiology of IIT.

A novel CC-chemokine homolog encoded by guinea pig cytomegalovirus.

Infection with cytomegalovirus (CMV) is persistent, even in the normal host. Periodic viral reactivation may have serious consequences, particularly if the infected individual is immunosuppressed, or pregnant. A number of CMV genes appear to contribute to the phenomena of evasion of host immune clearance, including homologs of cellular immune effector proteins, such as chemokines (CKs), chemokine receptor-like G protein-coupled receptors (GPCRs), and MHC class I molecules. To examine whether the guinea pig cytomegalovirus (GPCMV) encodes homologs of these cellular immunoregulatory genes, regions of the viral genome were sequenced and analyzed for the presence of conserved and novel open reading frames (ORFs) with potential homology to GPCR and CK proteins. A region in the Hind III 'D' region of the genome was identified which had strong identity to multiple beta (CC) chemokines, particularly members of the macrophage inflammatory protein 1 (MIP-1) family. Northern blot analysis indicated that this region of the genome was transcriptionally active, encoding a transcript of 1.7 kbp, which was synthesized with 'late' gene kinetics. This is the first identification of a CK gene encoded by GPCMV, and adds to the growing list of putative CMV immunomodulatory genes which appear to have been transduced from the host genome during the co-evolution of host and pathogen.

A macrophage inflammatory protein homolog encoded by guinea pig cytomegalovirus signals via CC chemokine receptor 1.

Cytomegaloviruses encode homologs of cellular immune effector proteins, including chemokines (CKs) and CK receptor-like G protein-coupled receptors (GPCRs). Sequence of the guinea pig cytomegalovirus (GPCMV) genome identified an open reading frame (ORF) which predicted a 101 amino acid (aa) protein with homology to the macrophage inflammatory protein (MIP) subfamily of CC (beta) CKs, designated GPCMV-MIP. To assess functionality of this CK, recombinant GPCMV-MIP was expressed in HEK293 cells and assayed for its ability to bind to and functionally interact with a variety of GPCRs. Specific signaling was observed with the hCCR1 receptor, which could be blocked with hMIP -1alpha in competition experiments. Migration assays revealed that GPCMV-MIP was able to induce chemotaxis in hCCR1-L1.2 cells. Antisera raised against a GST-MIP fusion protein immunoprecipitated species of approximately 12 and 10 kDa from GPCMV-inoculated tissue culture lysates, and convalescent antiserum from GPCMV-infected animals was immunoreactive with GST-MIP by ELISA assay. These results represent the first substantive in vitro characterization of a functional CC CK encoded by a cytomegalovirus.