Invariant natural killer T (iNKT) cells play a protective role in the development
of certain autoimmune diseases. However, their precise role in the pathogenesis
of autoimmune arthritis remains ...unclear. In this study, we examined the possible
contribution of iNKT cells in collagen-induced arthritis (CIA) by using iNKT cell-deficient
mice (Jα281−/− mice). CIA in these mice was markedly suppressed and interleukin
(IL)-17 production was reduced in a native type II collagen (CII)-specific T cell
response. Draining lymph nodes of CII-immunized Jα281−/− mice contained a significantly
low number of IL-17-producing T helper cells. To determine whether iNKT cells
produce IL-17, we measured IL-17 by enzyme-linked immunosorbent assay in iNKT
cells stimulated with the ligand, α-galactosylceramide (α-GalCer). Notably, splenocytes
from Jα281−/− mice stimulated in this way were negative for IL-17, whereas those
from C57BL/6 mice produced IL-17. Immunostaining for IL-17 in iNKT cells confirmed
intracellular staining of the protein. RT-PCR analysis showed that iNKT cells
expressed retinoid-related orphan receptor γT and IL-23 receptor. Moreover, cell
sorting demonstrated that NK1.1− iNKT cells were the main producers of IL-17 compared
with NK1.1+ iNKT cells. IL-17 production by iNKT cells was induced by IL-23-dependent
and -independent pathways, since iNKT produced IL-17 when stimulated with either
IL-23 or α-GalCer alone. Our findings indicate that iNKT cells are producers and
activators of IL-17 via IL-23- dependent and -independent pathways, suggesting
that they are key cells in the pathogenesis of CIA through IL-17.
Background: Chromosomal behavior during mitosis and meiosis depends in part on heterochromatic modifications such as histone H3 lysine-9 methylation (H3K9me). In fission yeast, the Heterochromatin ...Protein 1 homolog Swi6 recognizes H3K9me, silences transcription, and retains cohesin at pericentromeric repeats. Heterochromatin formation also depends on processing of transcripts derived from centromeric repeats by the RNAi machinery. The DDB1 homolog, Rik1, and histone methyltransferase, Clr4, act in a complex to promote H3K9me. However, the mechanism underlying this interaction is poorly understood.
Results: Using a cytological screen, we have identified two novel genes, dos1+ and dos2+, which are required for localization of Swi6. Deletion of either of these genes results in mitotic and meiotic chromosome missegregation, defects in mitotic centromeric cohesion and meiotic telomere clustering, and loss of heterochromatic silencing. Dos1 is predominantly located in the nucleus in a Dos2-dependent manner and directly interacts with Rik1. Each of these genes is required for the association of H3K9me with centromeric repeats, as well as for the production of small interfering RNAs.
Conclusions: Dos1 and Dos2 are required for the formation of heterochromatin in fission yeast. We hypothesize that the physical interaction between Dos1 and Rik1 represents a role in regulating activity of the Rik1/Clr4 complex. Dos2 contributes to this role by regulating Dos1 localization. Our findings suggest a mechanism for recruitment of Clr4 in the RNAi-dependent heterochromatin pathway, in which Dos1 and Dos2 are essential.
Aerosols have great impacts on atmospheric environment, human health, and earth's climate. Therefore, information on their spatial and temporal distribution is of paramount importance. Despite ...numerous studies have examined the variation and trends of BC and AOD over India, only very few have focused on their spatial distribution or even correlating the observations with model simulations. In the present study, a three-dimensional aerosol transport-radiation model coupled with a general circulation model. SPRINTARS, simulated atmospheric aerosol distributions including BC and aerosol optical properties, i.e., aerosol optical thickness (AOT), Ångström Exponent (AE), and single scattering albedo (SSA). The simulated results are compared with both BC measurements by aethalometer and aerosol optical properties measured by ground-based skyradiometer and by satellite sensor, MODIS/Terra over Hyderabad, which is a tropical urban area of India, for the year 2008. The simulated AOT and AE in Hyderabad are found to be comparable to ground-based measured ones. The simulated SSA tends to be higher than the ground-based measurements. Both these comparisons of aerosol optical properties between the simulations with different emission inventories and the measurements indicate that, firstly the model uncertainties derived from aerosol emission inventory cannot explain the gaps between the simulations and the measurements and secondly the vertical transport of BC and the treatment of BC-containing particles can be the main issue in the global model to solve the gap.
Objective: To determine whether occurrence, characteristics, and progression of systemic lupus erythematosus (SLE) are associated with polymorphism of the mannose binding lectin (MBL) gene and with ...serum MBL concentration. Methods: Codon 54 MBL gene polymorphism of 147 patients with SLE and 160 healthy controls was determined by polymerase chain reaction-restriction fragment length polymorphism. Serum concentration of MBL was measured by enzyme immunoassay. Fluctuations of serum MBL were analysed with respect to disease characteristics and activity. Results: Frequency of homozygosity for codon 54 minority allele was 6% (9/147) in patients with SLE, and significantly higher than in controls (p = 0.0294, Fisher’s exact test). MBL polymorphism in patients with SLE was not significantly associated with disease characteristics or immunological phenotypes. Patients homozygous for the B allele tended to have a higher risk of infection during treatment. Levels of C3 and CH50 were slightly, but significantly, associated with serum MBL concentration in patients with SLE homozygous for the majority allele. During the course of SLE, serum MBL concentration increased in 6/14 patients, and decreased in 7 after initiation of immunosuppressive treatment. Conclusions: MBL gene polymorphism influences susceptibility to SLE, but has no direct effect on disease characteristics. Serum MBL levels fluctuate during the course of SLE in individual patients. MBL genotyping may be useful in assessing the risk of infection during treatment of SLE.
Summary
Alpha‐carba‐GalCer (RCAI‐56), a novel synthetic analogue of α‐galactosylceramide (α‐GalCer), stimulates invariant natural killer T (NK T) cells to produce interferon (IFN)‐γ. IFN‐γ exhibits ...immunoregulatory properties in autoimmune diseases by suppressing T helper (Th)‐17 cell differentiation and inducing regulatory T cells and apoptosis of autoreactive T cells. Here, we investigated the protective effects of α‐carba‐GalCer on collagen‐induced arthritis (CIA) in mice. First, we confirmed that α‐carba‐GalCer selectively induced IFN‐γ in CIA‐susceptible DBA/1 mice in vivo. Then, DBA/1 mice were immunized with bovine type II collagen (CII) and α‐carba‐GalCer. The incidence and clinical score of CIA were significantly lower in α‐carba‐GalCer‐treated mice. Anti‐IFN‐γ antibodies abolished the beneficial effects of α‐carba‐GalCer, suggesting that α‐carba‐GalCer ameliorated CIA in an IFN‐γ‐dependent manner. Treatment with α‐carba‐GalCer reduced anti‐CII antibody production immunoglobulin (Ig)G and IgG2a and CII‐reactive interleukin (IL)‐17 production by draining lymph node (DLN) cells, did not induce apoptosis or regulatory T cells, and significantly increased the ratio of the percentage of IFN‐γ‐producing T cells to IL‐17‐producing T cells (Th1/Th17 ratio). Moreover, the gene expression levels of IL‐6 and IL‐23p19, Th17‐related cytokines, were reduced significantly in mice treated with α‐carba‐GalCer. In addition, we observed higher IFN‐γ production by NK T cells in α‐carba‐GalCer‐treated mice in the initial phase of CIA. These findings indicate that α‐carba‐GalCer polarizes the T cell response toward Th1 and suppresses Th17 differentiation or activation, suggesting that α‐carba‐GalCer, a novel NK T cell ligand, can potentially provide protection against Th17‐mediated autoimmune arthritis by enhancing the Th1 response.
An alternatively spliced variant of Smad2 with a deletion of exon 3 (Smad2Deltaexon3) is found in various cell types. Here, we studied the function of Smad2Deltaexon3 and compared it with those of ...wild-type Smad2 containing exon 3 (Smad2(wt)) and Smad3. When transcriptional activity was measured using the p3TP-lux construct, Smad2Deltaexon3 was more potent than Smad2(wt), and had activity similar to Smad3. Transcriptional activation of the activin-responsive element (ARE) of Mix.2 gene promoter by Smad2Deltaexon3 was also similar to that by Smad3, and slightly less potent than that by Smad2(wt). Phosphorylation by the activated transforming growth factor-beta type I receptor and heteromer formation with Smad4 occurred to similar extents in Smad2Deltaexon3, Smad2(wt), and Smad3. However, DNA binding to the activating protein-1 sites of p3TP-lux was observed in Smad2Deltaexon3 as well as in Smad3, but not in Smad2(wt). In contrast, Smad2(wt), Smad2Deltaexon3, and Smad3 efficiently formed ARE-binding complexes with Smad4 and FAST1, although Smad2(wt) did not directly bind to ARE. These results suggest that exon 3 of Smad2 interferes with the direct DNA binding of Smad2, and modifies the function of Smad2 in transcription of certain target genes.
Abstract Objectives The purpose of this study was to examine the histological correlation of native myocardial T1 and extracellular volume fraction (ECV) measurement at 3-T for the assessment of ...diffuse pathological changes in the myocardial tissue, including myocardial fibrosis and extracellular space in dilated cardiomyopathy (DCM). Background Cardiac magnetic resonance T1 techniques allow the quantification of diffuse myocardial fibrosis. However, there are no definitive head-to-head studies of native T1 versus ECV for the detection, quantification, and characterization of pathological changes in the myocardial tissue in DCM by using histological samples for confirmation. Methods A total of 36 subjects with DCM (31 men, mean age 56 ± 16 years) underwent pre- and post-contrast T1 mapping as well as late gadolinium enhancement (LGE) cardiac magnetic resonance at 3-T. Biopsy samples were used for the quantification of collagen volume fraction using picrosirius red staining and an extracellular space component from hematoxylin and eosin–stained myocardium. Results Nonischemic LGE was observed in 14 of 36 patients. Although patients with LGE had significantly greater biopsy-proven collagen volume fraction than those without LGE (21 ± 12% vs. 11 ± 8%; p < 0.01), there was substantial overlap of collagen volume fraction values between patients with and without LGE. Both native T1 value and ECV were similarly and significantly associated with biopsy-proven collagen volume fraction (r = 0.77 and r = 0.66, respectively; p < 0.05). Furthermore, ECV had a strong correlation with the biopsy-proven extracellular space component (r = 0.86), whereas native T1 had only a moderate correlation (r = 0.55). Interobserver and intraobserver reproducibility for native T1 and ECV were 0.89, 0.95, 0.96, and 0.98, respectively. Conclusions Native T1 exhibited comparable ability as ECV measurement in the detection and quantification of histological collagen volume fraction, with high reproducibility, and therefore diffuse myocardial fibrosis in DCM may be reliably assessed by native T1 mapping without the administration of gadolinium contrast agent. In addition, cardiac magnetic resonance–derived ECV showed excellent agreement with histological extracellular space.
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