Effects of microRNA-21 on the interleukin 12/signal transducer and activator of transcription 4 signaling pathway in asthmatic mice

MiRNA and Exosomal miRNA as New Biomarkers Useful to Phenotyping Severe Asthma

Severe asthma (SA) is a chronic inflammatory disease of the airways. Due to the extreme heterogeneity of symptoms, new biomarkers are currently needed. MiRNAs are non-coding RNAs that negatively regulate gene expression at the post-transcriptional level. In biological fluids, miRNAs are contained within exosomes, vesicles capable of giving miRNAs considerable stability and resistance to degradation by RNAses. The main function attributed to the exosomes is intercellular communication. The goal of our study was to analyze intracellular and exosomal miRNAs in order to demonstrate their potential use as non-invasive biomarkers of asthma by showing, in particular, their role in SA. We detected miRNAs by qRT-PCR in both serum and serum-derived-exosomes of asthmatic patients and healthy controls. The levels of almost all analyzed intracellular miRNAs (miR-21, miR-223, and let-7a) were greater in asthmatic patients vs. healthy control, except for miR-223. In detail, miR-21 was greater in SA, while let-7a increased in mild-to-moderate asthma. On the other hand, in exosomes, all analyzed miRNAs were higher in SA. This study identified a series of miRNAs involved in SA, highlighting their potential role in asthma development and progression. These results need validation on a larger cohort.

Role of microRNAs in type 2 diseases and allergen-specific immunotherapy

MicroRNAs (miRs) have gained scientific attention due to their importance in the pathophysiology of allergic diseases as well as their potential as biomarkers in allergen-specific treatment options. Their function as post-transcriptional regulators, controlling various cellular processes, is of high importance since any single miR can target multiple mRNAs, often within the same signalling pathway. MiRs can alter dysregulated expression of certain cellular responses and contribute to or cause, but in some cases prevent or repress, the development of various diseases. In this review article, we describe current research on the role of specific miRs in regulating immune responses in epithelial cells and specialized immune cells in response to various stimuli, in allergic diseases, and regulation in the therapeutic approach of allergen-specific immunotherapy (AIT). Despite the fact that AIT has been used successfully as a causative treatment option since more than a century, very little is known about the mechanisms of regulation and its connections with microRNAs. In order to fill this gap, this review aims to provide an overview of the current knowledge.

The Novel Regulatory Role of the lncRNA–miRNA–mRNA Axis in Chronic Inflammatory Airway Diseases

Chronic inflammatory airway diseases, characterized by airway inflammation and airway remodelling, are increasing as a cause of morbidity and mortality for all age groups and races across the world. The underlying molecular mechanisms involved in chronic inflammatory airway diseases have not been fully explored. MicroRNAs (miRNAs) and long noncoding RNAs (lncRNAs) have recently attracted much attention for their roles in the regulation of a variety of biological processes. A number of studies have confirmed that both lncRNAs and miRNAs can regulate the initiation and progression of chronic airway diseases by targeting mRNAs and regulating different cellular processes, such as proliferation, apoptosis, inflammation, migration, and epithelial–mesenchymal transition (EMT). Recently, accumulative evidence has shown that the novel regulatory mechanism underlying the interaction among lncRNAs, miRNAs and messenger RNAs (mRNAs) plays a critical role in the pathophysiological processes of chronic inflammatory airway diseases. In this review, we comprehensively summarized the regulatory roles of the lncRNA–miRNA–mRNA network in different cell types and their potential roles as biomarkers, indicators of comorbidities or therapeutic targets for chronic inflammatory airway diseases, particularly chronic obstructive pulmonary disease (COPD) and asthma.

Role of Non-Coding RNAs in Post-Transcriptional Regulation of Lung Diseases

Non-coding RNAs (ncRNAs), notably microRNAs (miRNAs) and long noncoding RNAs (lncRNAs), have recently gained increasing consideration because of their versatile role as key regulators of gene expression. They adopt diverse mechanisms to regulate transcription and translation, and thereby, the function of the protein, which is associated with several major biological processes. For example, proliferation, differentiation, apoptosis, and metabolic pathways demand fine-tuning for the precise development of a specific tissue or organ. The deregulation of ncRNA expression is concomitant with multiple diseases, including lung diseases. This review highlights recent advances in the post-transcriptional regulation of miRNAs and lncRNAs in lung diseases such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, and idiopathic pulmonary fibrosis. Further, we also discuss the emerging role of ncRNAs as biomarkers as well as therapeutic targets for lung diseases. However, more investigations are required to explore miRNAs and lncRNAs interaction, and their function in the regulation of mRNA expression. Understanding these mechanisms might lead to early diagnosis and the development of novel therapeutics for lung diseases.

MicroRNA-21 Deficiency Promotes the Early Th1 Immune Response and Resistance toward Visceral Leishmaniasis

MicroRNA-21 (miR-21) inhibits IL-12 expression and impairs the Th1 response necessary for control of Leishmania infection. Recent studies have shown that Leishmania infection induces miR-21 expression in dendritic cells and macrophages, and inhibition of miR-21 restores IL-12 expression. Because miR-21 is known to be expressed due to inflammatory stimuli in a wide range of hematopoietic cells, we investigated the role of miR-21 in regulating immune responses during visceral leishmaniasis (VL) caused by Leishmania donovani infection. We found that miR-21 expression was significantly elevated in dendritic cells, macrophages, inflammatory monocytes, polymorphonuclear neutrophils, and in the spleen and liver tissues after L. donovani infection, concomitant with an increased expression of disease exacerbating IL-6 and STAT3. Bone marrow dendritic cells from miR-21 knockout (miR-21KO) mice showed increased IL-12 production and decreased production of IL-10. On L. donovani infection, miR-21KO mice exhibited significantly greater numbers of IFN-γ- and TNF-α-producing CD4⁺ and CD8⁺ T cells in their organs that was associated with increased production of Th1-associated IFN-γ, TNF-α, and NO from the splenocytes. Finally, miR-21KO mice displayed significantly more developing and mature hepatic granulomas leading to reduction in organ parasitic loads compared with wild type counterparts. Similar results were noted in L. donovani-infected wild type mice after transient miR-21 depletion. These observations indicate that miR-21 plays a critical role in pathogenesis of VL by suppressing IL-12- and Th1-associated IFN-γ and also inducing disease-promoting induction of the IL-6 and STAT-3 signaling pathway. miR-21 could therefore be used as a potential target for developing host-directed treatment for VL.

Selective activation of cannabinoid receptor 2 regulates Treg/Th17 balance to ameliorate neutrophilic asthma in mice

Background

The cannabinoid receptor 2 (CNR2) plays a critical role in relieving asthma, with the mechanism still unclear. We aimed to investigate the mechanism of the CNR2 agonist (β-caryophyllene, β-Car) in regulating the balance of regulatory T cells (Treg) and T helper cell 17 (Th17) and thus its role in asthma.

Methods

The study group of 50 pathogen-free female BALB/c mice were randomly divided at 6–8 weeks old into five groups of Control, Asthma, Asthma + β-Car (10 mg/kg), Asthma + β-Car + SR144528 (specific CNR2 antagonist, 3 mg/kg), and Asthma + β-Car + CMD178 (inhibitor of Treg cell, 10 mg/kg). ELISA was conducted to evaluate the main inflammatory cytokines [interleukin (IL)-6, IL-8, and tumor necrosis factor-α], and those secreted by Treg (transforming growth factor-β and IL-10), and Th17 (IL-17A and IL-22). Markers of Treg and Th17 cells were assessed by flow cytometry. In vitro, the CD4⁺ T cells were sorted and directed to differentiate to Treg and Th17 cells. The expression levels of CNR2, STAT5 and JNK1/2 were investigated by western blot and immunofluorescence assay.

Results

β-Car relieved neutrophilic asthma severity in mice by elevating the marker genes’ expression of Treg and inhibiting those of Th17, causing an increased proportion of Treg to Th17. β-Car also promoted the directed differentiation of CD4⁺ T cells into Treg, but not Th17. Activation of the CNR2 regulated the Treg/Th17 balance and relieved neutrophilic asthma possibly through promotion of phosphorylation of STAT5 and JNK1/2.

Conclusions

The effect of the selective CNR2 agonist activating STAT5 and JNK1/2 signaling was to change the Treg/Th17 balance and reduce the inflammatory reaction, thus ameliorating neutrophilic asthma in a mouse model.

Exosomes: A Key Piece in Asthmatic Inflammation

Asthma is a chronic disease of the airways that has an important inflammatory component. Multiple cells are implicated in asthma pathogenesis (lymphocytes, eosinophils, mast cells, basophils, neutrophils), releasing a wide variety of cytokines. These cells can exert their inflammatory functions throughout extracellular vesicles (EVs), which are small vesicles released by donor cells into the extracellular microenvironment that can be taken up by recipient cells. Depending on their size, EVs can be classified as microvesicles, exosomes, or apoptotic bodies. EVs are heterogeneous spherical structures secreted by almost all cell types. One of their main functions is to act as transporters of a wide range of molecules, such as proteins, lipids, and microRNAs (miRNAs), which are single-stranded RNAs of approximately 22 nucleotides in length. Therefore, exosomes could influence several physiological and pathological processes, including those involved in asthma. They can be detected in multiple cell types and biofluids, providing a wealth of information about the processes that take account in a pathological scenario. This review thus summarizes the most recent insights concerning the role of exosomes from different sources (several cell populations and biofluids) in one of the most prevalent respiratory diseases, asthma.

MicroRNAs as Potential Regulators of Immune Response Networks in Asthma and Chronic Obstructive Pulmonary Disease

Chronic respiratory diseases (CRDs) are an important factor of morbidity and mortality, accounting for approximately 6% of total deaths worldwide. The main CRDs are asthma and chronic obstructive pulmonary disease (COPD). These complex diseases have different triggers including allergens, pollutants, tobacco smoke, and other risk factors. It is important to highlight that although CRDs are incurable, various forms of treatment improve shortness of breath and quality of life. The search for tools that can ensure accurate diagnosis and treatment is crucial. MicroRNAs (miRNAs) are small non-coding RNAs and have been described as promising diagnostic and therapeutic biomarkers for CRDs. They are implicated in multiple processes of asthma and COPD, regulating pathways associated with inflammation, thereby showing that miRNAs are critical regulators of the immune response. Indeed, miRNAs have been found to be deregulated in several biofluids (sputum, bronchoalveolar lavage, and serum) and in both structural lung and immune cells of patients in comparison to healthy subjects, showing their potential role as biomarkers. Also, miRNAs play a part in the development or termination of histopathological changes and comorbidities, revealing the complexity of miRNA regulation and opening up new treatment possibilities. Finally, miRNAs have been proposed as prognostic tools in response to both conventional and biologic treatments for asthma or COPD, and miRNA-based treatment has emerged as a potential approach for clinical intervention in these respiratory diseases; however, this field is still in development. The present review applies a systems biology approach to the understanding of miRNA regulatory networks in asthma and COPD, summarizing their roles in pathophysiology, diagnosis, and treatment.

MiR-135b Alleviates Airway Inflammation in Asthmatic Children and Experimental Mice with Asthma via Regulating CXCL12

OBJECTIVE

To clarify the possible influence of miR-135b on CXCL12 and airway inflammation in children and experimental mice with asthma.

METHODS

The expressions of miR-135b and CXCL12 were detected using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) in the serum of asthmatic children. Besides, the experimental asthmatic mice were established by aerosol inhalation of ovalbumin (OVA) followed by the treatment with agomiR-135b and antagomir-135b. Pathological changes of lung tissues were observed via HE staining and PAS staining. Besides, the airway hyperresponsiveness of mice was elevated and bronchoalveolar lavage fluid (BALF) was isolated for cell categorization and counting. The inflammatory cytokines in BALF were determined by enzyme-linked immunosorbent assay (ELISA), and the infiltration of Th17 cells in lung tissues was measured using flow cytometry.

RESULTS

MiR-135b was downregulated and CXCL12 was upregulated in asthmatic children and mice. Overexpression of miR-135b may down-regulate CXCL12 expression in the lung of OVA mice, resulting in significant decreases in inflammatory infiltration, hyperplasia of goblet cell, airway hyperresponsiveness, cell quantity, as well as the quantity of eosinophilic granulocytes, neutrophils and lymphocytes in BALF. Also, the levels of inflammatory cytokines (IL-4, IL-5, IL-13 and IL-17) and the ratio of Th17 cells and IL-17 levels in lung tissues were decreased. However, miR-135b downregulation reversed these changes in OVA mice.

CONCLUSION

MiR-135b may inhibit immune responses of Th17 cells to alleviate airway inflammation and hyperresponsiveness in asthma possibly by targeting CXCL12, showing the potential value in asthma treatment.

Emerging role of non-coding RNAs in allergic disorders

RNA transcripts that not undergo translation into polypeptides recently came into focus of research. Long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) comprise the most important groups of these transcripts. LncRNAs have a length over 200 nucleotides and like mRNAs, have regulated transcription in a tissue specific manner. Biogenesis and function of lncRNAs is related to cell differentiation, response to stimuli and regulation of immune responses. LncRNAs can interact with both miRNAs and mRNAs. MiRNAs are characterized by a length of 22-24 nucleotides. MiRNAs regulate expression of genes at the post-transcriptional level. LncRNAs together with miRNAs are considered as regulators of the immune system. Alterations in their biogenesis is an important mechanism in the development immune related disorders. CircRNAs are products of aberrant maturation of protein-coding transcripts in a process of back-splicing, in which a single strand RNA molecule attains a closed circle shape. Despite a low expression, some circRNA were found to titrate miRNAs and interfere with maturation of legitimate protein-coding transcripts. We summarize the current knowledge on the role of non-coding transcripts in allergic disorders: asthma, atopic dermatitis, allergic rhinitis and urticaria. The reviewed data suggest lncRNA and miRNAs as therapeutic targets and biomarkers of allergic disorders.

STAT4: an immunoregulator contributing to diverse human diseases

Signal transducer and activator of transcription 4 (STAT4) is a member of the STAT family and localizes to the cytoplasm. STAT4 is phosphorylated after a variety of cytokines bind to the membrane, and then dimerized STAT4 translocates to the nucleus to regulate gene expression. We reviewed the essential role played by STAT4 in a wide variety of cells and the pathogenesis of diverse human diseases, especially many kinds of autoimmune and inflammatory diseases, via activation by different cytokines through the Janus kinase (JAK)-STAT signaling pathway.

Immunological characteristics of Interleukin-2 receptor subunit beta (IL-2Rβ) in flounder (Paralichtlys olivaceus): Implication for IL-2R function

Interleukin-2 receptor subunit beta of flounder (Paralichthys olivace, fIL-2Rβ) was annotated on the NCBI, its gene was cloned and characterized functionally in this study. And then the amino acids sequences and tertiary structure of fIL-2Rβ were analyzed, respectively. RT-PCR and ImageJ analyzed showed that fIL-2Rβ mRNA were expressed in the gill, spleen, kidney, intestines, liver, blood, muscle and skin, which showed high signals in spleen and blood. And then the recombinant protein of fIL-2Rβ extracellular region and its polyclonal antibodies were produced, native fIL-2Rβ molecules in flounder peripheral blood leukocytes (PBLs) were identified at 60.7 kDa by Mass spectrometry, which were in accordance with the molecular mass of full fIL-2Rβ protein calculated on the predicted protein sequence. Then the IL-2Rβ+ cell in T/B lymphocytes were characterized by Flow cytometry and indirect immunofluorescence assay, respectively. The results showed that the percentages of IL-2Rβ+ leukocytes, IL-2Rβ+/CD4+, IL-2Rβ+/IgM+ lymphocytes were 18.4 ± 2.7%, 4.5 ± 0.8%, 4.3% ± 0.5 in PBLs, and were 13.6 ± 0.9%, 4.6 ± 1.1%, 6.1% ± 0.4 in spleen, similarly, the percentages of IL-2Rβ+ leukocytes, IL-2Rβ+/CD4+, IL-2Rβ+/IgM+ lymphocytes were 9.4 ± 0.3%, 4.0 ± 0.5%, 5.7 ± 0.1% in head kidney, respectively. After KLH injection, compared with control group, the gene expression of IL-2, IL-2Rβ, CD3, TCR, CD79b and IgM in spleen of flounder were up-regulated, respectively (p < 0.05). And the FCM results showed that the percentages of IL-2Rβ+ leukocytes in PBLs were significantly increased post Keyhole limpet hemocyanin (KLH) injection, which peaked 23.9 ± 0.9% at 9^th day (p < 0.05). To our knowledge, those results first reported that the characteristics of IL-2R and IL-2R + molecules were expressed on both B and T lymphocytes in fish. At the same time, this study lays a foundation for further exploring the interaction between IL-2 and IL-2R to promote cell proliferation and carrying out biological functions.

MicroRNA-21 aggravates chronic obstructive pulmonary disease by promoting autophagy

MicroRNAs and autophagy play important roles in chronic obstructive pulmonary disease (COPD). This study was designed to explore the role of microRNA-21 (miR-21) induced autophagy in COPD. Using the C57BL/6, miR-21-/- mice and human bronchial epithelial (16HBE) cell line, we found that in the lung tissues of mice, the level of autophagy in the COPD model group was significantly higher than that in the control group. However, compared to the COPD model, the level of autophagy was significantly lower in the miR-21-/- CSE+CS group. In the COPD model, miR-21 was overexpressed. Moreover, in human bronchial epithelial (16HBE) cells exposed to cigarette smoke extract (CSE), miR-21 expression was upregulated and autophagy was notably increased. In addition, pretreatment of 16HBE cells with miR-21 inhibitor significantly inhibited autophagy activity and decreased apoptosis, indicating that miR-21 is involved in CSE-induced autophagy and apoptosis. The results showed that miR-21 could increase autophagy and promote the apoptosis of 16HBE cells in COPD. This information contributes to our further understanding of COPD.

CD80 and CD86 knockdown in dendritic cells regulates Th1/Th2 cytokine production in asthmatic mice

Dendritic cells (DCs) are associated with the activation and differentiation of T helper (Th) cells. Cluster of differentiation (CD)80 and CD86, the co-stimulatory molecules highly expressed in DCs, have are prominent in promoting the differentiation of Th cells toward Th2 cells. However, little is known about the effect of CD80 and CD86 knockdown on Th1/Th2 cytokine production in mature DCs (mDCs). The aim of the present study was to investigate whether small-interfering RNA (siRNA) could suppress the surface expression of CD80 and CD86 in mDCs. The effects of CD80 and CD86 knockdown in mDCs on Th1/Th2 cytokine expression were examined using an asthmatic murine model. DCs were isolated, separated and cultured in vitro. Flow cytometry was used to examine the expression of CD11c, CD80 and CD86 on the DCs. The DCs were transfected with CD80- and CD86-specific siRNA, while non-siRNA and negative siRNA controls were also designed. Then, the mRNA and protein expression levels of CD80 and CD86 were determined by reverse transcription-quantitative polymerase chain reaction and flow cytometry, respectively. The levels of interferon (IFN)-γ and interleukin (IL)-4 produced by T cells co-cultured with mDCs were measured by enzyme-linked immunosorbent assay. Substantial downregulation of CD80 and CD86 mRNA and protein levels were observed in the mDCs following transfection with siRNA. The level of IFN-γ produced by T cells co-cultured with mDCs was significantly increased in the siRNA group, while IL-4 production was significantly decreased. These results show that specific targeting of CD80 and CD86 with siRNA is able to suppress CD80/CD86 expression and consequently regulate Th1/Th2 cytokine levels by increasing IFN-γ production and decreasing IL-4 levels in an asthmatic murine model.