Stronger inflammatory/cytotoxic T cell response in women identified by microarray analysis

Women develop chronic inflammatory autoimmune diseases like lupus more often than men. The mechanisms causing the increased susceptibility are incompletely understood, although estrogen is believed to contribute. Chronic immune stimulation characterizes many autoimmune disorders. We hypothesized that repeated stimulation may cause a different T cell immune response in women than men. Microarray approaches were used to compare gene expression in T cells from healthy men and women with and without repeated stimulation. Four days following a single stimulation only 25% of the differentially expressed, gender-biased genes were expressed at higher levels in the women. In contrast, following restimulation 72% were more highly expressed in women. Immune response genes were significantly over-represented among the genes upregulated in women, and among the immune response genes, the inflammatory/cytotoxic effector genes interferon gamma (IFNG), lymphotoxin beta (LTB), granzyme A (GZMA), interleukin-12 receptor beta2 (IL12RB2), and granulysin (GNLY) were among those overexpressed to the greatest degree. In contrast, IL17A was the only effector gene more highly expressed in men. Estrogen response elements were identified in the promoters of half of the overexpressed immune genes in women, and in <10% of the male biased genes. The differential expression of inflammatory/cytotoxic effector molecules in restimulated female T cells may contribute to the differences in autoimmune diseases between women and men

Preliminary Evidence That High-Dose Vitamin C has a Vascular Disrupting Action in Mice

High intravenous doses of vitamin C (ascorbic acid) have been reported to benefit cancer patients but the data are controversial and there is incomplete knowledge of what physiological mechanisms might be involved in any response. Vitamin C is taken up efficiently by cells expressing SVCT2 transporters and since vascular endothelial cells express SVCT2, we explored the hypothesis that administration of high dose vitamin C (up to 5 g/kg) to mice might affect vascular endothelial function. A single administration of vitamin C to mice induced time- and dose-dependent increases in plasma concentrations of the serotonin metabolite 5-hydroxyindole acetic acid (5-HIAA), a marker for vascular disrupting effects. Responses were comparable to those for the tumor vascular disrupting agents vadimezan and fosbretabulin. High-dose vitamin C administration decreased tumor serotonin concentrations, consistent with the release of serotonin from platelets and its metabolism to 5-HIAA. High-dose vitamin C also significantly increased the degree of hemorrhagic necrosis in tumors removed after 24 hours, and significantly decreased tumor volume after 2 days. However, the effect on tumor growth was temporary. The results support the concept that vitamin C at high dose increases endothelial permeability, allowing platelets to escape and release serotonin. Plasma 5-HIAA concentrations could provide a pharmacodynamic biomarker for vitamin C effects in clinical studies

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No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37805/1/1780380937_ftp.pd

Effect of an inhibitor of DNA methylation on T cells. II. 5-azacytidine induces self-reactivity in antigen-specific T4+ cells

During T-cell maturation, thymocytes interact with thymic stromal major histocompatibility complex (MHC) determinants and thymic hormones, and proliferate, apparently in response to MHC gene products, in the absence of antigen. The maturing thymocytes also express a series of cell surface molecules, at one stage coexpressing T4, T6, and T8. Mature T cells express either T4 or T8, lack T6, bear the T3-Ti receptor complex on the cell surface, and require antigen in addition to MHC determinants to proliferate. To study whether DNA methylation may be involved in regulating phenotypic and functional changes observed during thymocyte maturation, cloned, T4+ Interleukin-2 dependent, antigen-specific T cells were treated with an inhibitor of DNA methylation, 5-azacytidine (5-azaC). The 5-azaC treated cells lost the requirement for antigen and could be activated by autologous macrophages alone. Anti-class II and anti-T3, but not anti-class I monoclonal antibodies, inhibited activation of 5-azaC treated T4+ cells by macrophages, implying that the T3-Ti receptor complex may be recognizing class II MHC molecules without antigen. No changes in T3 and T4 expression were noted, and neither T8 nor T6 was induced.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25959/1/0000025.pd

Oxidative Stress, T Cell DNA Methylation, and Lupus

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107387/1/art38427.pd

Decreased ERK and JNK signaling contribute to gene overexpression in “senescent” CD4+CD28– T cells through epigenetic mechanisms

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141118/1/jlb0137.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141118/2/jlb0137-sup-0001.pd

Instability and freezing in a solidifying melt conduit

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Physica D: Nonlinear Phenomena 240 (2011): 131-139, doi:10.1016/j.physd.2010.10.009.Previous works have shown that when liquid flows in a pipe whose boundary temperature is below freezing, a tubular drainage conduit forms surrounded by solidified material that freezes shut under the appropriate combination of forcing conditions. We conduct laboratory experiments with wax in which the tube freezes shut below a certain value of flux from a pump. As the flux is gradually decreased to this value, the total pressure drop across the length of the tube first decreases to a minimum value and then rises before freezing. Previous theoretical models of a tube driven by a constant pressure drop suggest that once the pressure minimum is reached, the states for a lower flux should be unstable and the tube should therefore freeze up. In our experiments, flux and pressure drop were coupled, and this motivates us to extend the theory for low-Reynolds number flow through a tube with solidification to incorporate a simple pressure drop-flux relationship. Our model predicts a steady-state relationship between flux and pressure drop that has a minimum of the pressure as the flux is varied. The stability properties of these steady states depend on the boundary conditions: for a fixed flux, they are all stable, whereas for fixed pressure drop, only those with a flux larger than that at the pressure drop minimum are stable. For a mixed pressure-flux condition, the stability threshold of the steady states lies between these two end members. This provides a possible mechanism for the experimental observations.Support was received from the Geophysical Fluid Dynamics Program, which is supported by the Ocean Sciences Division of the National Science Foundation under Grant OCE-0325296, and from the Oceanography Section of the Office of Naval Research under Grant N00014-07-1-0776. The laboratory experiments were supported by the Deep Ocean Exploration Institute of W.H.O.I

Prostaglandin E2 increases fibroblast geneâ specific and global DNA methylation via increased DNA methyltransferase expression

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154365/1/fsb2026009012.pd

Overexpression of CD70 and overstimulation of IgG synthesis by lupus T cells and T cells treated with DNA methylation inhibitors

Objective Generalized DNA hypomethylation contributes to altered T cell function and gene expression in systemic lupus erythematosus (SLE). Some of the overexpressed genes participate in the disease process, but the full repertoire of genes affected is unknown. Methylation-sensitive T cell genes were identified by treating T cells with the DNA methyltransferase inhibitor 5-azacytidine and comparing gene expression with oligonucleotide arrays. CD70, a costimulatory ligand for B cell CD27, was one gene that reproducibly increased. We then determined whether CD70 is overexpressed on T cells treated with other DNA methylation inhibitors and on SLE T cells, and determined its functional significance. Methods Oligonucleotide arrays, real-time reverse transcription–polymerase chain reaction, and flow cytometry were used to compare CD70 expression in T cells treated with 2 DNA methyltransferase inhibitors (5-azacytidine and procainamide) and 3 ERK pathway inhibitors known to decrease DNA methyltransferase expression (U0126, PD98059, and hydralazine). The consequences of CD70 overexpression were tested by coculture of autologous T and B cells with and without anti-CD70 and measuring IgG production by enzyme-linked immunosorbent assay. The results were compared with those of T cells from lupus patients. Results SLE T cells and T cells treated with DNA methylation inhibitors overexpressed CD70 and overstimulated B cell IgG production. The increase in IgG synthesis was abrogated by anti-CD70. Conclusion SLE T cells and T cells treated with DNA methyltransferase inhibitors and ERK pathway inhibitors overexpress CD70. This increased B cell costimulation and subsequent immunoglobulin overproduction may contribute to drug-induced and idiopathic lupus.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34311/1/20255_ftp.pd

Increased immunoglobulin response to [gamma]-interferon by lymphocytes from patients with systemic lupus erythematosus

The factors responsible for abnormal B-cell activation in systemic lupus erythematosus (SLE) are incompletely understood. This study tested the hypothesis that the abnormal B-cell activation observed in human SLE may be due to an augmented response to a helper signal. We demonstrated that non-T cells from 10 of 19 SLE patients increased IgG production in response to interferon-[gamma] (IFN-[gamma]) by a mean factor of 20.9 +/- 3.9 over resting levels, while controls stimulated a mean factor of 3.0 +/- 0.5 (P < 0.005). We found no relationship of IFN-[gamma] responsiveness to disease activity. Serotyping for HLA A, B, C, and D loci suggested that the hyperresponsiveness may be genetically linked to HLA-Cw7. We conclude that IFN-[gamma] may contribute to the development and perpetuation of SLE in a subset of patients with SLE.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27486/1/0000529.pd