T-helper cell tolerance to ubiquitous nuclear antigens

Extracellular vesicles extracted from young donor serum attenuate inflammaging via partially rejuvenating aged T-cell immunotolerance

Biologic aging results in a chronic inflammatory condition, termed inflammaging, which establishes a risk for such age-related diseases as neurocardiovascular diseases; therefore, it is of great importance to develop rejuvenation strategies that are able to attenuate inflammaging as a means of intervention for age-related diseases. A promising rejuvenation factor that is present in young blood has been found that can make aged neurons younger; however, the component in the young blood and its mechanism of action are poorly elucidated. We assessed rejuvenation in naturally aged mice with extracellular vesicles (EVs) or exosomes extracted from young murine serum on the basis of different spectrums of microRNAs in these vesicles from young and old sera. We found that EVs extracted from young donor mouse serum, rather than EVs extracted from old donor mouse serum or non-EV supernatant extracted from young donor mouse serum, were able to attenuate inflammaging in old mice. Inflammaging is attributed to multiple factors, one of which is thymic aging-released self-reactive T cell-induced pathology. We found that the attenuation of inflammaging after treatment with EVs from young serum partially contributed to the rejuvenation of thymic aging, which is characterized by partially reversed thymic involution, enhancement of negative selection signals, and reduced autoreactions in the periphery. Our results provide evidence for understanding of the potential rejuvenation factor in the young donor serum, which holds great promise for the development of novel therapeutics to reduce morbidity and mortality caused by age-related inflammatory diseases.-Wang, W., Wang, L., Ruan, L., Oh, J., Dong, X., Zhuge, Q., Su, D.-M. Extracellular vesicles extracted from young donor serum attenuate inflammaging via partially rejuvenating aged T-cell immunotolerance.

NQO1 and NQO2 Regulation of Humoral Immunity and Autoimmunity

NAD(P)H:quinone oxidoreductase 1 (NQO1) and NRH:quinone oxidoreductase 2 (NQO2) are cytosolic enzymes that catalyze metabolic reduction of quinones and derivatives. NQO1-null and NQO2-null mice were generated that showed decreased lymphocytes in peripheral blood, myeloid hyperplasia, and increased sensitivity to skin carcinogenesis. In this report, we investigated the in vivo role of NQO1 and NQO2 in immune response and autoimmunity. Both NQO1-null and NQO2-null mice showed decreased B-cells in blood, lower germinal center response, altered B cell homing, and impaired primary and secondary immune responses. NQO1-null and NQO2-null mice also showed susceptibility to autoimmune disease as revealed by decreased apoptosis in thymocytes and pre-disposition to collagen-induced arthritis. Further experiments showed accumulation of NADH and NRH, cofactors for NQO1 and NQO2, indicating altered intracellular redox status. The studies also demonstrated decreased expression and lack of activation of immune-related factor NF-kappaB. Microarray analysis showed altered chemokines and chemokine receptors. These results suggest that the loss of NQO1 and NQO2 leads to altered intracellular redox status, decreased expression and activation of NF-kappaB, and altered chemokines. The results led to the conclusion that NQO1 and NQO2 are endogenous factors in the regulation of immune response and autoimmunity.

Regulatory T Cells and Systemic Lupus Erythematosus

CD4+CD25+ regulatory T cells (Treg) constitute an important mechanism of peripheral immune tolerance. Organ-specific autoimmune conditions, such as thyroiditis and insulin-dependent diabetes mellitus have been attributed to a breakdown of this tolerance mechanism. However, this T-cell subset has not been well studied in patients and mice with systemic lupus erythematosus (SLE; lupus). The information that has been gathered so far using new tools that discriminate Treg from activated T cells indicates that reduced numbers of Treg may exist in patients with lupus. In addition, potential defects in SLE Treg function have been documented in humans and mice. Our group has demonstrated equivalent proportions of thymic Treg in lupus prone and normal mice. We therefore propose that Treg function in SLE is the more important factor to address in future studies of murine lupus. Recent studies have shown that Toll-like receptor (TLR) ligation can result in an abrogation of Treg-mediated suppression; specifically ligation of TLR-2, -4, -8 and -9. We address this new information about TLRs and Treg and propose a model for Treg tolerance breakdown to nucleic acid-binding SLE autoantigens.

Transcriptional modulation of TCR, Notch and Wnt signaling pathways in SEB-anergized CD4+ T cells

Gene expression changes in CD4 + Vbeta8+ T cells energized by in vivo exposure to staphylococcal enterotoxin B (SEB) bacterial superantigen compared to CD4 + Vbeta8+ non-energic T cells were assessed using DNA microarrays containing 5184 murine complementary DNAs. Anergy in splenic T cells of SEB-immunized BALB/c mice was verified by dramatically reduced proliferative capacity and an 8 x overexpression of GRAIL mRNA in CD4 + Vbeta8+ T cells taken from mice 7 days after injection. At an Associative t-test threshold of P<0.0005, 96 genes were overexpressed or detected only in anergic T cells, while 256 genes were suppressed or not detected in anergic T cells. Six of eight differential expressions tested using real-time quantitative PCR were validated. Message for B-Raf was detected only in non-anergic cells, while expression of the TCR signaling modulator Slap (Src-like adapter protein) and the TCR zeta-chain specific phosphatase Ptpn3 was enhanced. Modulation of multiple genes suggests downregulation of Wnt/beta-catenin signaling and enhanced Notch signaling in the anergic cells. Consistent with previous reports in a non-superantigen in vivo anergy model, mRNA for CD18 and the transcription factor Satb1 (special AT-rich-binding protein 1) was increased in SEB-energized T cells. This is the first report of global transcriptional changes in CD4+ T cells made anergic by superantigen exposure.

Genetic Determination of T Cell Help in Loss of Tolerance to Nuclear Antigens

Sle1 is a major lupus susceptibility locus in NZM2410 lupus model that is associated with a loss of tolerance to nuclear Ags. At least three genes, Sle1a, Sle1b, and Sle1c contribute to Sle1, and their relative role in lupus pathogenesis is unknown. We show here that Sle1-expressing CD4(+) T cells present an activated phenotype associated with increased proliferation and cytokine production. In addition, Sle1 CD4(+) T cells provide help to anti-chromatin B cells to produce anti-nuclear antibodies, whether or not these B cells express Sle1. The Sle1a locus alone accounts for all these Sle1 phenotypes, implying that a specific genetic defect in Sle1a is necessary and sufficient to produce autoreactive T cells. However, Sle1c induces intermediate T cell activation and only provides help to Sle1-expressing anti-chromatin-producing B cells, demonstrating the synergic interactions between Sle1c T and Sle1 B cells. Moreover, Sle1a and Sle1c were associated with a significantly reduced level of CD4(+)CD25(+) regulatory T cells that precedes autoantibody production, suggesting a causal relationship with the generation of autoreactive T cells. Our study identifies for the first time that a specific genetic defect is responsible for lupus pathogenesis by inducing autoreactive T cells to break self-tolerance and that this genetic defect is also associated with a decreased number of regulatory T cells.