Biomedical subjects

Daniel J Shaffer

Publications and source records attributed to Daniel J Shaffer.

8 recordsLinked to original sources

PubMed2005

Searching QTL by gene expression: analysis of diabesity.

BACKGROUND: Recent developments in sequence databases provide the opportunity to relate the expression pattern of genes to their genomic position, thus creating a transcriptome map. Quantitative trait loci (QTL) are phenotypically-defined chromosomal regions that contribute to allelically variant biological traits, and by overlaying QTL on the transcriptome, the search for candidate genes becomes extremely focused. RESULTS: We used our novel data mining tool, ExQuest, to select genes within known diabesity QTL showing enriched expression in primary diabesity affected tissues. We then quantified transcripts in adipose, pancreas, and liver tissue from Tally Ho mice, a multigenic model for Type II diabetes (T2D), and from diabesity-resistant C57BL/6J controls. Analysis of the resulting quantitative PCR data using the Global Pattern Recognition analytical algorithm identified a number of genes whose expression is altered, and thus are novel candidates for diabesity QTL and/or pathways associated with diabesity. CONCLUSION: Transcription-based data mining of genes in QTL-limited intervals followed by efficient quantitative PCR methods is an effective strategy for identifying genes that may contribute to complex pathophysiological processes.

Algorithms↗

PubMed2005

Activated NKT cells inhibit autoimmune diabetes through tolerogenic recruitment of dendritic cells to pancreatic lymph nodes.

NKT cell activation by alpha-galactosylceramide (alpha-GalCer) inhibits autoimmune diabetes in NOD mice, in part by inducing recruitment to pancreatic lymph nodes (PLNs) of mature dendritic cells (DCs) with disease-protective effects. However, how activated NKT cells promote DC maturation, and what downstream effect this has on diabetogenic T cells was unknown. Activated NKT cells were found to produce a soluble factor(s) inducing DC maturation. Initially, there was a preferential accumulation of mature DCs in the PLNs of alpha-GalCer-treated NOD mice, followed by a substantial increase in T cells. Adoptive transfer of a diabetogenic CD8 T cell population (AI4) induced a high rate of disease (75%) in PBS-treated NOD recipients, but not in those pretreated with alpha-GalCer (8%). Significantly, more AI4 T cells accumulated in PLNs of alpha-GalCer than PBS-treated recipients, while no differences were found in mesenteric lymph nodes from each group. Compared with those in mesenteric lymph nodes, AI4 T cells entering PLNs underwent greater levels of apoptosis, and the survivors became functionally anergic. NKT cell activation enhanced this process. Hence, activated NKT cells elicit diabetes protection in NOD mice by producing a soluble factor(s) that induces DC maturation and accumulation in PLNs, where they subsequently recruit and tolerize pathogenic T cells.

Adjuvants, Immunologic↗

PubMed2005

Accelerated wound healing of alkali-burned corneas in MRL mice is associated with a reduced inflammatory signature.

PURPOSE: The present study was conducted to investigate healing of alkali-burned corneas in MRL/MpJ (MRL) mice. METHODS: Gross, clinical, and histologic criteria were used to compare healing of alkali-burned corneas in MRL and control C57BL/6J (B6) mice. Effects of neutrophil depletion of B6 mice and allogeneic reconstitution of B6 mice with MRL bone marrow on wound healing were evaluated. Gene expression patterns in normal and wounded corneas were surveyed with array-based quantitative real-time RT-PCR (AQPCR). RESULTS: MRL mice showed accelerated reepithelialization and decreased corneal opacity compared with B6 mice after alkali wounding. Marked inflammatory cell infiltration and fibrosis were evident in the corneas and anterior chambers of B6 mice. MRL mice showed less severe lesions, except for stromal edema. Rapid reepithelialization and reduced keratitis/iritis were also observed in neutrophil-depleted B6 mice, but not in B6 mice reconstituted with MRL bone marrow. AQPCR showed transcriptional changes of fewer genes associated with inflammation and corneal tissue homeostasis in alkali-burned corneas from MRL mice. Increased expression of an anti-inflammatory gene, Socs1, and a gene associated with healing, Mmp1a, were evident in MRL corneas. CONCLUSIONS: Alkali-burned corneas heal faster and more completely in MRL mice than in B6 mice, by means of rapid reepithelialization, reduced inflammation, and reduced fibrosis. Reduced inflammation, including decreased neutrophil infiltrates and the lack of a robust proinflammatory gene expression signature correlates with the rapid healing. However, the rapid-healing phenotype is not intrinsic to MRL hematopoietic progenitor cells.

Animals↗

PubMed2004

Regulation of B cell differentiation and plasma cell generation by IL-21, a novel inducer of Blimp-1 and Bcl-6.

IL-21 is a type I cytokine whose receptor is expressed on T, B, and NK cells. Within the B cell lineage, IL-21 regulates IgG1 production and cooperates with IL-4 for the production of multiple Ab classes in vivo. Using IL-21-transgenic mice and hydrodynamics-based gene delivery of IL-21 plasmid DNA into wild-type mice as well as in vitro studies, we demonstrate that although IL-21 induces death of resting B cells, it promotes differentiation of B cells into postswitch and plasma cells. Thus, IL-21 differentially influences B cell fate depending on the signaling context, explaining how IL-21 can be proapoptotic for B cells in vitro yet critical for Ag-specific Ig production in vivo. Moreover, we demonstrate that IL-21 unexpectedly induces expression of both Blimp-1 and Bcl-6, indicating mechanisms as to how IL-21 can serve as a complex regulator of B cell maturation and terminal differentiation. Finally, BXSB-Yaa mice, which develop a systemic lupus erythematosus-like disease, have greatly elevated IL-21, suggesting a role for IL-21 in the development of autoimmune disease.

Animals↗

PubMed2004

The MHC class I-like Fc receptor promotes humorally mediated autoimmune disease.

The MHC class I family-like Fc receptor, FcRn, is normally responsible for extending the life span of serum IgG Ab's, but whether this molecule contributes to autoimmune pathogenesis remains speculative. To determine directly whether this function contributes to humoral autoimmune disease, we examined whether a deficiency in the FcRn heavy chain influences autoimmune arthritis in the K/BxN mouse model. FcRn deficiency conferred either partial or complete protection in the arthritogenic serum transfer and the more aggressive genetically determined K/BxN autoimmune arthritis models. The protective effects of an FcRn deficiency could be overridden with excessive amounts of pathogenic IgG Ab's. The therapeutic saturation of FcRn by high-dose intravenous IgG (IVIg) also ameliorated arthritis, directly implicating FcRn blockade as a significant mechanism of IVIg's anti-inflammatory action. The results suggest that FcRn is a potential therapeutic target that links the initiation and effector phases of humoral autoimmune disease.

Animals↗

PubMed2003

A single nucleotide polymorphism in the Emp3 gene defines the H4 minor histocompatibility antigen.

Minor histocompatibility antigens (minor H antigen) elicit strong T-cell-mediated responses during both graft rejection and graft versus leukemia (GvL) among MHC-matched individuals (where MHC is major histocompatibility complex). Employing expression-cloning methodology, we have identified a cDNA clone, MI-35, encoding the immunodominant H4b minor H antigen within the classical mouse H4 complex. The minimal antigenic epitope derived from H4b presented on Kb class I MHC is SGIVYIHL (SYL8) and the polymorphism is due to C-->T nucleotide modification in p3 resulting in the change of threonine (ACT) to isoleucine (ATT). The results presented here demonstrate that amino acid variation in the allelic epitopes results in the low abundance of H4a peptide. The differential peptide copy number resulted in an immunodominant cytotoxic T cells (CTL) response directed against H4b while the anti-B6 response directed against H4a was easily dominated. These results provide a molecular mechanism for the H4 minor H antigen and suggest a novel mechanism by which alloantigenic disparity caused by conservative amino acid changes can be augmented by posttranslational antigen processing events.

Amino Acid Sequence↗

PubMed2003

The MHC class I-like IgG receptor controls perinatal IgG transport, IgG homeostasis, and fate of IgG-Fc-coupled drugs.

Abs of the IgG isotype are efficiently transported from mother to neonate and have an extended serum t(1/2) compared with Abs of other isotypes. Circumstantial evidence suggests that the MHC class I-related protein, the neonatal FcR (FcRn), is the FcR responsible for both in vivo functions. To understand the phenotypes imposed by FcRn, we produced and analyzed mice with a defective FcRn gene. The results provide direct evidence that perinatal IgG transport and protection of IgG from catabolism are mediated by FcRn, and that the latter function is key to IgG homeostasis, essential for generating a potent IgG response to foreign Ags, and the basis of enhanced efficacy of Fc-IgG-based therapeutics. FcRn is therefore a promising therapeutic target for enhancing protective humoral immunity, treating autoimmune disease, and improving drug efficacy.

Abatacept↗

PubMed2003

Customized molecular phenotyping by quantitative gene expression and pattern recognition analysis.

Description of the molecular phenotypes of pathobiological processes in vivo is a pressing need in genomic biology. We have implemented a high-throughput real-time PCR strategy to establish quantitative expression profiles of a customized set of target genes. It enables rapid, reproducible data acquisition from limited quantities of RNA, permitting serial sampling of mouse blood during disease progression. We developed an easy to use statistical algorithm--Global Pattern Recognition--to readily identify genes whose expression has changed significantly from healthy baseline profiles. This approach provides unique molecular signatures for rheumatoid arthritis, systemic lupus erythematosus, and graft versus host disease, and can also be applied to defining the molecular phenotype of a variety of other normal and pathological processes.

Algorithms↗