IntroductionIncreasing evidence indicates that microRNAs (miRNAs) play a critical role in the pathogenesis of inflammatory diseases. The aim of the study was to investigate the expression pattern and function of miRNAs in CD4+ T cells from patients with rheumatoid arthritis (RA).MethodsThe expression profile of miRNAs in CD4+ T cells from synovial fluid (SF) and peripheral blood of 33 RA patients was determined by microarray assay and validated by qRT-PCR analysis. The correlation between altered expression of miRNAs and cytokine levels was determined by linear regression analysis. The role of miR-146a overexpression in regulating T cell apoptosis was evaluated by flow cytometry. A genome-wide gene expression analysis was further performed to identify miR-146a-regulated genes in T cells.ResultsmiRNA expression profile analysis revealed that miR-146a expression was significantly upregulated while miR-363 and miR-498 were downregulated in CD4+ T cells of RA patients. The level of miR-146a expression was positively correlated with levels of tumor necrosis factor-alpha (TNF-α), and in vitro studies showed TNF-α upregulated miR-146a expression in T cells. Moreover, miR-146a overexpression was found to suppress Jurkat T cell apoptosis. Finally, transcriptome analysis of miR-146a overexpression in T cells identified Fas associated factor 1 (FAF1) as a miR-146a-regulated gene, which was critically involved in modulating T cell apoptosis.ConclusionsWe have detected increased miR-146a in CD4+ T cells of RA patients and its close correlation with TNF-α levels. Our findings that miR-146a overexpression suppresses T cell apoptosis indicate a role of miR-146a in RA pathogenesis and provide potential novel therapeutic targets.

Key Points miR-146a may be involved in the pathogenesis of ALPS by targeting Fas. Sustained expression of miR-146a in B cells is the major factor leading to the enhanced homeostatic expansion of B and T cells.

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Pneumonia is a common respiratory disease worldwide, which is preventable and treatable; however, it is recognized as a leading cause of mortality in children. The present study aimed to investigate the role and mechanism of microRNA (miR)‑20a in inflammation in pediatric pneumonia. Clinical serum samples were collected from children with pneumonia and healthy children. Initially, the serum expression levels of miR‑20a were detected by reverse transcription‑quantitative polymerase chain reaction. Subsequently, A549 cells were randomly divided into four groups: Control group; lipopolysaccharide (LPS; 1 µg/ml) group; LPS + miR‑20a group; and LPS + miR‑20a + pyrrolidine dithiocarbamate (PDTC; 100 mmol/l) group. The concentrations of interleukin‑6 (IL‑6), tumor necrosis factor (TNF)‑α and C‑reactive protein (CRP) in clinical serum samples and A549 cells were determined by ELISA. In addition, the protein expression levels of inhibitor of nuclear factor (NF)‑κB α (IκBα) and phosphorylated (p)‑NF‑κB were measured by western blotting. The results demonstrated that miR‑20a was upregulated in children with pneumonia and in lung cells with LPS‑induced inflammatory injury (P<0.01). In addition, compared with the LPS group, cells in the LPS + miR‑20a group exhibited increased expression levels of IL‑6, TNF‑α and CRP (P<0.05). Overexpression of miR‑20a also resulted in upregulation of the expression levels of IκBα and p‑NF‑κB compared with in the LPS group (P<0.05). Furthermore, treatment with the NF‑κB inhibitor PDTC inhibited the expression of inflammatory factors compared with in the LPS + miR‑20a group (P<0.05). In conclusion, the present study indicated that miR‑20a is upregulated in pediatric pneumonia, and overexpression of miR‑20a may promote inflammation through activation of the NF‑κB signaling pathway.

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Oligo-microarray can be fabricated on modified surface of glass slides involving immobilization of oligonucleotides. In this study, glass slides were modified with acrylic acid-co-acrylamide copolymer and EDC (1-ethyl-3(3-dimethylaminopropyl)-carbodiimide)/NHS (N-hydroxysuccinimide) by covalent linkage method, and covalent immobilization of unmodified oligonucleotide on the glass surface was achieved. The platform with binding of stable and sensitive oligonucleotides was prepared for oligo-microarray fabrication. An optimum concentration of 0.5 g/L was used for spotting. The lengths of 26 to 70 mer oligonucleotides were immobilized on the surface efficiently. The spots were approximately 160 nm in diameter and their mean value of fluorescent intensity was measured in the range of 3.2 x 10(4) to 7.3 x 10(4) after hybridization. The modified glass surface was scanned by SEM and the dendritic structure was observed. Results showed that the process of preparation of the modified glass surface was simple and cost effective, and the modified surface can be used for the oligo-microarray fabrication and also attachment of protein, PNA etc.

A complementary DNA (cDNA) fragment library from SH-SY5Y cells is constructed using a restriction display polymerase chain reaction (RD-PCR) technique. Messenger RNA (mRNA) is extracted from SH-SY5Y cells and single-strand cDNA synthesised using an anchored oligo primer (dT18). The second strand is produced by nick translation. The double strands are cleaved with the restriction enzyme Sau3AI and the fragments ligated with universal linker. The products are amplified with universal primers and selected primers, ligated into the pMDI8-T vector, and then sequenced. The library constructed contained 136 subgroups, each comprising seven to 12 cDNA fragments. RD-PCR proved a simple, effective way to construct a cDNA library, and this will contribute to the investigation of gene expression in the neuron in future microarray studies.

MicroRNAs, a class of small non-coding RNAs, play a major role in various cellular activities during psychological and pathological processes through inhibiting the direct targets expression. MiR-146a is remarkable induced after LPS stimulation and virus infection and highly expressed in patients with immune disorders such as rheumatoid arthritis, Sjögren's syndrome and psoriasis. To date, whether the high level of miR-146a contributes the pathogenesis of immune disorder disease s remains unknown. In order to elucidate precious functions of miR-146a in vivo, we generated a miR-146a over-expression transgenic mouse. The level of miR-146a has been increased 3 to 8 folds higher than WT mice, which is similar to the levels of patients with immune disorders. miR-146a transgenic mice spontaneously developed a ALPS feathered disease with the distinct manifests including elevated double negative T cells, enlarged spleens and lymph nodes, higher serum IgG, and inflammatory infiltrations in livers and lungs at early age. Further analysis revealed that Fas was the direct target of miR-146a and was specifically down-regulated in germinal center B cells. In addition, B cells of miR-146a TG mice showed hyper-homeostasis proliferation after adoptive transferred into SCID mice. Collectively, our results clearly establish the notion that miR-146a may get involved in the pathogenesis of ALPS through targeting Fas in GC B cells and might be a potential therapeutic target.