Decreased signal transducers and activators of transcription (STAT) protein expression in lymphatic organs during EAE development in mice

Effects of Castration on miRNA, lncRNA, and mRNA Profiles in Mice Thymus

Thymic degeneration and regeneration are regulated by estrogen and androgen. Recent studies have found that long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are involved in organ development. In this study, RNA sequencing (RNA-seq) results showed that ovariectomy significantly affected 333 lncRNAs, 51 miRNAs, and 144 mRNAs levels (p < 0.05 and |log2fold change| > 1), and orchiectomy significantly affected 165 lncRNAs, 165 miRNAs, and 208 mRNA levels in the thymus. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that differentially expressed genes (DEGs) were closely related to cell development and immunity. Next, we constructed two lncRNA–miRNA–mRNA networks using Cytoscape based on the targeting relationship between differentially expressed miRNAs (DEMs) and DEGs and differentially expressed lncRNAs (DELs) analyzed by TargetScan and miRanda. Besides, we screened DEGs that were significantly enriched in GO and in ceRNA networks to verify their expression in thymocytes and thymic epithelial cells (TECs). In addition, we analyzed the promoter sequences of DEGs, and identified 25 causal transcription factors. Finally, we constructed transcription factor-miRNA-joint target gene networks. In conclusion, this study reveals the effects of estrogen and androgen on the expression of miRNAs, lncRNAs, and mRNAs in mice thymus, providing new insights into the regulation of thymic development by gonadal hormones and non-coding RNAs.

Analysis of STAT1, STAT2 and STAT3 mRNA expression levels in the blood of patients with multiple sclerosis

BACKGROUND

Multiple sclerosis (MS) is the most common chronic, inflammatory, autoimmune disease of the central nervous system (CNS) maintained by the secretion of a large number of cytokines [1]. The signal transducer and activator of transcription (STAT) family has an essential role in transmitting many of the cytokine-mediated signals and failure in the signaling process contributes to the etiopathogenesis of MS.

METHODS

This study aimed to assess STAT1, STAT2 and STAT3 gene expression in the blood of 50 relapsing-remitting MS (RR-MS) patients and 50 healthy controls by TaqMan Quantitative Real-Time PCR.

RESULTS

The results showed that STAT1 gene expression was significantly up-regulated (p= 0.023), whereas STAT2 gene expression was significantly down-regulated (p< 0.0001) in MS patients compared to controls. On the other hand, there was no significant difference between MS patients and controls for STAT3 gene expression (p= 0.837). In addition, there was no significant correlation between the expression of STAT1, STAT2, STAT3 genes and clinical findings, such as the level of physical disability in MS patients (according to the Kurtzke Expanded Disability Status Scale (EDSS) criterion) and disease duration.

CONCLUSION

A significant positive correlation was demonstrated between STAT1 and STAT2 and also between STAT1 and STAT3. This study shows for the first time that a comparison of the relative quantitative expression of three different STAT genes in the blood cells of MS patients compared to controls revealed marked differences in the expression of the STAT family genes that might reflect their different roles in the pathogenesis of MS. These transcripts might be useful biomarkers for evaluating the efficacy of IFN treatment of the MS patients.

Strain differences in thymic atrophy in rats immunized for EAE correlate with the clinical outcome of immunization

An accumulating body of evidence suggests that development of autoimmune pathologies leads to thymic dysfunction and changes in peripheral T-cell compartment, which, in turn, perpetuate their pathogenesis. To test this hypothesis, thymocyte differentiation/maturation in rats susceptible (Dark Agouti, DA) and relatively resistant (Albino Oxford, AO) to experimental autoimmune encephalomyelitis (EAE) induction was examined. Irrespective of strain, immunization for EAE (i) increased the circulating levels of IL-6, a cytokine causally linked with thymic atrophy, and (ii) led to thymic atrophy reflecting partly enhanced thymocyte apoptosis associated with downregulated thymic IL-7 expression. Additionally, immunization diminished the expression of Thy-1, a negative regulator of TCRαβ-mediated signaling and activation thresholds, on CD4+CD8+ TCRαβ^lo/hi thymocytes undergoing selection and thereby impaired thymocyte selection/survival. This diminished the generation of mature CD4+ and CD8+ single positive TCRαβ^hi thymocytes and, consequently, CD4+ and CD8+ recent thymic emigrants. In immunized rats, thymic differentiation of natural regulatory CD4+Foxp3+CD25+ T cells (nTregs) was particularly affected reflecting a diminished expression of IL-7, IL-2 and IL-15. The decline in the overall thymic T-cell output and nTreg generation was more pronounced in DA than AO rats. Additionally, differently from immunized AO rats, in DA ones the frequency of CD28- cells secreting cytolytic enzymes within peripheral blood CD4+ T lymphocytes increased, as a consequence of thymic atrophy-related replicative stress (mirrored in CD4+ cell memory pool expansion and p16^INK4a accumulation). The higher circulating level of TNF-α in DA compared with AO rats could also contribute to this difference. Consistently, higher frequency of cytolytic CD4+ granzyme B+ cells (associated with greater tissue damage) was found in spinal cord of immunized DA rats compared with their AO counterparts. In conclusion, the study indicated that strain differences in immunization-induced changes in thymopoiesis and peripheral CD4+CD28- T-cell generation could contribute to rat strain-specific clinical outcomes of immunization for EAE.