Fra-2-expressing macrophages promote lung fibrosis in mice.

Idiopathic Pulmonary Fibrosis (IPF) is a deadly disease with limited therapies. Tissue fibrosis is associated with Type 2 immune response, although the causal contribution of immune cells is not defined. The AP-1 transcription factor Fra-2 is upregulated in IPF lung sections and Fra-2 transgenic mice (Fra-2tg) exhibit spontaneous lung fibrosis. Here we show that Bleomycin-induced lung fibrosis is attenuated upon myeloid-inactivation of Fra-2 and aggravated in Fra-2tg bone marrow chimeras. Type VI collagen (ColVI), a Fra-2 transcriptional target, is up-regulated in three lung fibrosis models, and macrophages promote myofibroblast activation in vitro in a ColVI- and Fra-2-dependent manner. Fra-2 or ColVI inactivation does not affect macrophage recruitment and alternative activation, suggesting that Fra-2/ColVI specifically controls the paracrine pro-fibrotic activity of macrophages. Importantly, ColVI knock-out mice (KO) and ColVI-KO bone marrow chimeras are protected from Bleomycin-induced lung fibrosis. Therapeutic administration of a Fra-2/AP-1 inhibitor reduces ColVI expression and ameliorates fibrosis in Fra-2tg mice and in the Bleomycin model. Finally, Fra-2 and ColVI positively correlate in IPF patient samples and co-localize in lung macrophages. Therefore, the Fra-2/ColVI pro-fibrotic axis is a promising biomarker and therapeutic target for lung fibrosis, and possibly other fibrotic diseases.

Development of Low Parasitic Light Sensitivity and Low Dark Current 2.8 µm Global Shutter Pixel.

Abstract: We developed a low parasitic light sensitivity (PLS) and low dark current 2.8 µm global shutter pixel. We propose a new inner lens design concept to realize both low PLS and high quantum efficiency (QE). 1/PLS is 7700 and QE is 62% at a wavelength of 530 nm. We also propose a new storage-gate based memory node for low dark current. P-type implants and negative gate biasing are introduced to suppress dark current at the surface of the memory node. This memory node structure shows the world smallest dark current of 9.5 e-/s at 60 °C.

Medium-chain fatty acid-sensing receptor, GPR84, is a proinflammatory receptor.

G protein-coupled receptor 84 (GPR84) is a putative receptor for medium-chain fatty acids (MCFAs), whose pathophysiological roles have not yet been clarified. Here, we show that GPR84 was activated by MCFAs with the hydroxyl group at the 2- or 3-position more effectively than nonhydroxylated MCFAs. We also identified a surrogate agonist, 6-n-octylaminouracil (6-OAU), for GPR84. These potential ligands and the surrogate agonist, 6-OAU, stimulated [(35)S]GTP binding and accumulated phosphoinositides in a GPR84-dependent manner. The surrogate agonist, 6-OAU, internalized GPR84-EGFP from the cell surface. Both the potential ligands and 6-OAU elicited chemotaxis of human polymorphonuclear leukocytes (PMNs) and macrophages and amplified LPS-stimulated production of the proinflammatory cytokine IL-8 from PMNs and TNFα from macrophages. Furthermore, the intravenous injection of 6-OAU raised the blood CXCL1 level in rats, and the inoculation of 6-OAU into the rat air pouch accumulated PMNs and macrophages in the site. Our results indicate a proinflammatory role of GPR84, suggesting that the receptor may be a novel target to treat chronic low grade inflammation associated-disease.

CD8+CD45RA+CCR7+FOXP3+ T cells with immunosuppressive properties: a novel subset of inducible human regulatory T cells.

CD8 T cells stimulated with a suboptimal dose of anti-CD3 Abs (100 pg/ml) in the presence of IL-15 retain a naive phenotype with expression of CD45RA, CD28, CD27, and CCR7 but acquire new functions and differentiate into immunosuppressive T cells. CD8+CCR7+ regulatory T cells (Tregs) express FOXP3 and prevent CD4 T cells from responding to TCR stimulation and entering the cell cycle. Naive CD4 T cells are more susceptible to inhibition than memory cells. The suppressive activity of CD8+CCR7+ Tregs is not mediated by IL-10, TGF-ß, CTLA-4, CCL4, or adenosine and relies on interference with very early steps of the TCR signaling cascade. Specifically, CD8+CCR7+ Tregs prevent TCR-induced phosphorylation of ZAP70 and dampen the rise of intracellular calcium in CD4 T cells. The inducibility of CD8+CCR7+ Tregs is correlated with the age of the individual with PBLs of donors older than 60 y yielding low numbers of FOXP3(low) CD8 Tregs. Loss of CD8+CCR7+ Tregs in the elderly host may be of relevance in the aging immune system as immunosenescence is associated with a state of chronic smoldering inflammation.

Inhibitory CD8+ T cells in autoimmune disease.

Rheumatologists have long been focused on developing novel immunotherapeutic agents to manage such prototypic autoimmune diseases as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). The ultimate challenge in providing immunosuppressive treatment for patients with RA and SLE has derived from the dilemma that both protective and harmful immune responses result from adaptive immune responses, mediated by highly diverse, antigen-specific T and B cells endowed with powerful effector functions and the ability for long-lasting memory. As regulatory/suppressor T cells can suppress immunity against any antigen, including self-antigens, they emerge as an ideal therapeutic target. Several distinct subtypes of CD8(+) suppressor cells (Ts) have been described that could find application in treating RA or SLE. In a xenograft model of human synovium, CD8(+)CD28(-)CD56(+) T cells effectively suppressed rheumatoid inflammation. Underlying mechanisms involve conditioning of antigen presenting cells (APC). Adoptively transferred CD8(+) T cells characterized by IL-16 secretion have also exhibited disease-inhibitory effects. In mice with polyarthritis, CD8(+) Ts suppressed inflammation by IFNgamma-mediated modulation of the tryptophan metabolism in APC. In SLE animal models, CD8(+) Ts induced by a synthetic peptide exerted suppressive activity mainly via the TGFbeta-Foxp3-PD1 pathway. CD8(+) Ts induced by histone peptides were found to downregulate disease activity by secreting TGFbeta. In essence, disease-specific approaches may be necessary to identify CD8(+) Ts optimally suited to treat immune dysfunctions in different autoimmune syndromes.

Mechanism of gene expression of Arabidopsis glutathione S-transferase, AtGST1, and AtGST11 in response to aluminum stress.

The gene expression of two Al-induced Arabidopsis glutathione S-transferase genes, AtGST1 and AtGST11, was analyzed to investigate the mechanism underlying the response to Al stress. An approximately 1-kb DNA fragment of the 5'-upstream region of each gene was fused to a beta-glucuronidase (GUS) reporter gene (pAtGST1::GUS and pAtGST11::GUS) and introduced into Arabidopsis ecotype Landsberg erecta. The constructed transgenic lines showed a time-dependent gene expression to a different degree in the root and/or leaf by Al stress. The pAtGST1::GUS gene was induced after a short Al treatment (maximum expression after a 2-h exposure), while the pAtGST11::GUS gene was induced by a longer Al treatment (approximately 8 h for maximum expression). Since the gene expression was observed in the leaf when only the root was exposed to Al stress, a signaling system between the root and shoot was suggested in Al stress. A GUS staining experiment using an adult transgenic line carrying the pAtGST11::GUS gene supported this suggestion. Furthermore, Al treatment simultaneously with various Ca depleted conditions in root region enhanced the gene expression of the pAtGST11::GUS in the shoot region. This result suggested that the degree of Al toxicity in the root reflects the gene response of pAtGST11::GUS in the shoot via the deduced signaling system. Both transgenic lines also showed an increase of GUS activity after cold stress, heat stress, metal toxicity, and oxidative damages, suggesting a common induction mechanism in response to the tested stresses including Al stress.

An intronic SNP in a RUNX1 binding site of SLC22A4, encoding an organic cation transporter, is associated with rheumatoid arthritis.

Rheumatoid arthritis is a common inflammatory disease with complex genetic components. We investigated the genetic contribution of the cytokine gene cluster in chromosome 5q31 to susceptibility to rheumatoid arthritis in the Japanese population by case-control linkage disequilibrium (LD) mapping using single nucleotide polymorphisms (SNPs). Here we report that there is significant association between rheumatoid arthritis and the organic cation transporter gene SLC22A4 (P = 0.000034). We show that expression of SLC22A4 is specific to hematological and immunological tissues and that SLC22A4 is also highly expressed in the inflammatory joints of mice with collagen-induced arthritis. A SNP affects the transcriptional efficiency of SLC22A4 in vitro, owing to an allelic difference in affinity to Runt-related transcription factor 1 (RUNX1), a transcriptional regulator in the hematopoietic system. A SNP in RUNX1 is also strongly associated with rheumatoid arthritis (P = 0.00035). Our data indicate that the regulation of SLC22A4 expression by RUNX1 is associated with susceptibility to rheumatoid arthritis, which may represent an example of an epistatic effect of two genes on this disorder.

Functional haplotypes of PADI4, encoding citrullinating enzyme peptidylarginine deiminase 4, are associated with rheumatoid arthritis.

Individuals with rheumatoid arthritis frequently have autoantibodies to citrullinated peptides, suggesting the involvement of the peptidylarginine deiminases citrullinating enzymes (encoded by PADI genes) in rheumatoid arthritis. Previous linkage studies have shown that a susceptibility locus for rheumatoid arthritis includes four PADI genes but did not establish which PADI gene confers susceptibility to rheumatoid arthritis. We used a case-control linkage disequilibrium study to show that PADI type 4 is a susceptibility locus for rheumatoid arthritis (P = 0.000008). PADI4 was expressed in hematological and rheumatoid arthritis synovial tissues. We also identified a haplotype of PADI4 associated with susceptibility to rheumatoid arthritis that affected stability of transcripts and was associated with levels of antibody to citrullinated peptide in sera from individuals with rheumatoid arthritis. Our results imply that the PADI4 haplotype associated with susceptibility to rheumatoid arthritis increases production of citrullinated peptides acting as autoantigens, resulting in heightened risk of developing the disease.