No abstract

The chytrid fungus, Batrachochytrium dendrobatidis, causes chytridiomycosis and is a major contributor to global amphibian declines. Although amphibians have robust immune defenses, clearance of this pathogen is impaired. Because inhibition of host immunity is a common survival strategy of pathogenic fungi, we hypothesized that B. dendrobatidis evades clearance by inhibiting immune functions. We found that B. dendrobatidis cells and supernantants impaired lymphocyte proliferation and induced apoptosis; however, fungal recognition and phagocytosis by macrophages and neutrophils was not impaired. Fungal inhibitory factors were resistant to heat, acid, and protease. Their production was absent in zoospores and reduced by nikkomycin Z, suggesting that they may be components of the cell wall. Evasion of host immunity may explain why this pathogen has devastated amphibian populations worldwide.

The majority of the genome is noncoding and was believed to be nonfunctional. However, it is now appreciated that transcriptional control of protein coding genes resides within these noncoding regions. Thousands of genes encoding long intergenic noncoding RNAs (lincRNAs) have been recently identified throughout the genome, which positively or negatively regulate transcription of neighboring target genes. Both TMEVPG1 and its mouse orthologue encode lincRNAs and are positioned near the interferon gamma gene (IFNG). Here we show that transcription of both mouse and human TMEVPG1 genes is Th1 selective and dependent upon Stat4 and T-bet, transcription factors that drive the Th1 differentiation program. Ifng expression is partially restored in Stat4−/−Tbx21−/− cells through co-expression of T-bet and Tmevpg1 and Tmevpg1 expression contributes to but alone is not sufficient to drive Th1-dependent Ifng expression. Our results suggest that TMEVPG1 belongs to the general class of lincRNAs that positively regulate gene transcription.

Autoimmune diseases affect 3–5% of the population, are mediated by the immune response to self-Ags, and are characterized by the site of tissue destruction. We compared expression levels of >4,000 genes in PBMC of control individuals before and after immunization to those of individuals with four distinct autoimmune diseases. The gene expression profile of the normal immune response exhibits coordinate changes in expression of genes with related functions over time. In contrast, each individual from all autoimmune diseases displays a similar gene expression profile unrelated to the pattern of the immunized group. To our surprise, genes with a distinct expression pattern in autoimmunity are not necessarily “immune response” genes, but are genes that encode proteins involved in apoptosis, cell cycle progression, cell differentiation, and cell migration.

The 'histone-code' hypothesis proposes that cell fate 'decisions' are achieved through the creation of stable epigenetic histone 'marks' at gene loci. Here we explored the formation of marks of repressive methylation of histone 3 at lysine 9 (H3-K9) and of H3-K27 at the locus encoding interferon-gamma (Ifng locus) during the commitment of naive T cells to the T helper type 1 (TH1) and TH2 lineages. Methylation of H3-K9 across the Ifng locus was rapidly induced in differentiating TH1 and TH2 cells and was sustained in TH1 cells. In contrast, TH2 differentiation caused loss of methylation of H3-K9 and gain of methylation of H3-K27 by mechanisms dependent on the transcription factors GATA-3 and STAT6. Thus, histone-methylation marks at the Ifng locus are highly dynamic, which may ensure higher-order transcriptional regulation during early lineage commitment.

An oxidized form of thiocyanate accumulated during incubation of lactoperoxidase or myeloperoxidase with thiocyanate ion and low concentrations of peroxide. Addition of one mole of peroxide resulted in loss of one mole of thiocyanate and formation of one mole of the oxidation product. The oxidation product reacted with two moles of sulfhydryl to yield one mole of disulfide and one mole of thiocyanate. The same product was obtained by alkaline hydrolysis of thiocyanogen. The product is proposed to be hypothiocyanite ion. The peroxidases may catalyze the oxidation of thiocyanate to hypothiocyanite, or to thiocyanogen. Hypothiocyanite may be the antimicrobial agent formed during peroxidase-catalyzed oxidation of thiocyanate.Hypothiocyanite decomposed slowly with a second-order rate constant of 0.1 M-' s-l at 25 OC. When the amount of peroxide added approached the amount of thiocyanate, the yield of hypothiocyanite reached a maximum and then declined. This result suggested that hypothiocyanite was oxidized by excess peroxide. Efforts to produce high concentrations of hypothiocyanite were unsuccessful, even when thiocyanate was well in excess of peroxide. As the hypothiocyanite concentration approached 0.5 mM, decomposition was accelerated and small amounts of cyanide were produced. Hypothiocyanite reacted stoichiometrically with cyanide to give products that did not oxidize sulfhydryls. Hydrolysis of thiocyanogen at neutral pH also resulted in rapid decomposition and formation of cyanide.

Long noncoding RNAs (lncRNAs) regulate an array of biological processes in cells and organ systems. Less is known about their expression and function in lymphocyte lineages. Here we have identified >2000 lncRNAs expressed in human T cell cultures and those which display a TH lineage specific pattern of expression and are intragenic or adjacent to TH lineage specific genes encoding proteins with immunologic functions. One lncRNA cluster selectively expressed by the effector TH2 lineage consists of four alternatively spliced transcripts that regulate expression of TH2 cytokines, IL-4, IL-5 and IL-13. Genes encoding this lncRNA cluster in humans overlap the RAD50 gene and thus are contiguous with the previously described TH2 locus control region (LCR) in the mouse. Given its genomic synteny with the TH2 LCR, we refer to this lncRNA cluster as TH2-LCR lncRNA.

Objective. We sought to determine interrelationships among expression of lincRNA-p21, a long intergenic non-coding RNA, activity of NF-κB, and responses to methotrexate in rheumatoid arthritis (RA) by analyzing patient samples and cell culture models. Methods. Expression levels of long non-coding RNAs and messenger RNAs were determined by quantitative reverse transcription-polymerase chain reaction. Western blotting and flow cytometry were used to quantify levels of intracellular proteins. Intracellular NF-κB was determined using an NF-κB luciferase reporter plasmid. Results. RA patients expressed reduced basal levels of lincRNA-p21 and increased basal levels of phosphorylated p65 (RelA), a marker of NF-κB activation. RA subjects not receiving MTX expressed lower levels of lincRNA-p21 and higher levels of phosphorylated p65 compared to RA subjects receiving low-dose MTX. In cell culture using primary cells and transformed cell lines, we found that MTX induced lincRNA-p21 through a DNA-PKcs-dependent mechanism. Deficiencies of PRKDC mRNA levels in RA subjects were also corrected by MTX, in vivo. Further, MTX lowered NF-κB activity in TNF-α treated cells through a DNA-PKcs-dependent mechanism via induction of lincRNA-p21. Finally, we found that depressed levels of TP53 and lincRNA-p21 increased NF-κB activity in cell lines. Decreased levels of lincRNA-p21 did not alter NFKB1 or RELA transcripts. Rather, lincRNA-p21 physically bound to RELA mRNA. Conclusion. Our findings support a model whereby depressed levels of lincRNA-p21 in RA contribute to increased NF-κB activity. MTX decreases basal levels of NF-κB activity by increasing lincRNA-p21 through a DNA-PKcs dependent mechanism.