TLR9-induced miR-155 and Ets-1 decrease expression of CD1d on B cells in SLE

Inflammatory factor-mediated miR-155/SOCS1 signaling axis leads to Treg impairment in systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune disorder associated with the decrease and functional impairment of regulatory T cells (Tregs). In the current study, we explored the interplay of miR-155 and suppressor of cytokine signaling 1 (SOCS1) in regulating Treg function and stability in SLE.

METHODS

Clinical samples from healthy subjects and SLE patients were collected, and a mouse model of SLE was established to profile the expression pattern of miR-155 and SCOS1 in Tregs. Tregs isolated from mouse spleen were stimulated by inflammatory cytokines to confirm involvement of miR-155/SOCS1 axis in dictating Treg stability and function. We also administrated synthetic miR-155 inhibitor in SLE animal model to evaluate the potential effect on rescuing Treg function and alleviating SLE progression.

RESULTS

Tregs from SLE patients and SLE-induced mice exhibited a downregulation of SOCS1 and an upregulation of miR-155. In Tregs stimulated by inflammatory cytokines, Nuclear factor kappa B (NF-κB) signaling activation was required for the change of SOCS1 and miR-155 expression. miR-155 served as a negative regulator to dampen SOCS1 expression in inflammation-stimulated Tregs. The transfection of miR-155 mimic impaired the suppressive function and differentiation of Tregs through targeting SOCS1. In contrast, miR-155 inhibition improved Treg function under inflammatory stimulation and alleviated SLE conditions in the mouse model.

CONCLUSION

Inflammation-induced miR-155 impairs Treg stability and function in SLE through decreasing SOCS1 expression. Targeting miR-155 might be developed as an intervention to mitigate SLE conditions.

Decoding the connection between SLE and DNA Sensors: A comprehensive review

Systemic lupus erythematosus (SLE) is recognized as a prevalent autoimmune disorder characterized by a multifaceted pathogenesis potentially influenced by a combination of environmental factors, genetic predisposition, and hormonal regulation. The continuous study of immune system activation is especially intriguing. Analysis of blood samples from individuals with SLE reveals an abnormal increase in interferon levels, along with the existence of anti-double-stranded DNA antibodies. This evidence suggests that the development of SLE may be initiated by innate immunity. The presence of abnormal dsDNA fragments can activate DNA sensors within cells, particularly immune cells, leading to the initiation of downstream signaling cascades that result in the upregulation of relevant cytokines and the subsequent initiation of adaptive immune responses, such as B cell differentiation and T cell activation. The intricate pathogenesis of SLE results in DNA sensors exhibiting a wide range of functions in innate immune responses that are subject to variation based on cell types, developmental processes, downstream effector signaling pathways and other factors. The review aims to reorganize how DNA sensors influence signaling pathways and contribute to the development of SLE according to current studies, with the aspiration of furnishing valuable insights for future investigations into the pathological mechanisms of SLE and potential treatment approaches.

Anaphylatoxin signaling activates macrophages to control intracellular Rickettsia proliferation

IMPORTANCE

Pathogenic Rickettsia species are extremely dangerous bacteria that grow within the cytoplasm of host mammalian cells. In most cases, these bacteria are able to overpower the host cell and grow within the protected environment of the cytoplasm. However, a dramatic conflict occurs when Rickettsia encounter innate immune cells; the bacteria can "win" by taking over the host, or the bacteria can "lose" if the host cell efficiently fights the infection. This manuscript examines how the immune complement system is able to detect the presence of Rickettsia and alert nearby cells. Byproducts of complement activation called anaphylatoxins are signals that "activate" innate immune cells to mount an aggressive defensive strategy. This study enhances our collective understanding of the innate immune reaction to intracellular bacteria and will contribute to future efforts at controlling these dangerous infections.

An update on epigenetic regulation in autoimmune diseases

Autoimmune diseases (AIDs) generally manifest as chronic immune disorders characterized by significant heterogeneity and complex symptoms. The discordant incidence of AIDs between monozygotic twins guided people to attach importance to environmental factors. Epigenetics is one of the major ways to be influenced, some of them can even occur years before clinical diagnosis. With the advent of high-throughput omics times, the mysterious veil of epigenetic modification in AIDs has been gradually unraveled, and some progress has been made in utilizing it as indicators of diagnosis and disease activity. For example, the hypomethylated IFI44L promoter in diagnosing systematic lupus erythematosus (SLE). More recently, newly identified noncoding RNAs (ncRNAs), including long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), are also believed to be involved in the etiology of AIDs while the initial factor behind those epigenetic alterations can be diverse from metabolism to microbiota. Update and comprehensive insights into epigenetics in AIDs can help us understand the pathogenesis and further orchestrate it to benefit patients in the future. Therefore, we reviewed the latest epigenetic findings in SLE, rheumatoid arthritis (RA), Type 1 diabetes (T1D), systemic sclerosis (SSc) primarily from cellular levels.

Inhibition of miR-155 Attenuates CD14+ Monocyte-Mediated Inflammatory Response and Oxidative Stress in Psoriasis Through TLR4/MyD88/NF-κB Signaling Pathway

PURPOSE

Previous studies showed the link of CD14+ monocytes to inflammation and oxidation in psoriasis. In the present study, we investigated the regulatory role of miR-155 in CD14+ monocyte function in psoriasis.

MATERIALS AND METHODS

CD14+ monocytes were isolated from peripheral blood by magnetic bead separation method and its function was assessed following silence of miR-155 by lentivirus transfection with or without inhibition of TLR4 pathway. CCK8 and EdU were used to assess the proliferation of CD14+ monocytes. Expression levels of SOCS1, TLR4 and MyD88 proteins were determined by Western blotting, while expression levels of IL-6, TNF-α, ROS, MDA and T-AOC were measured by ELISA kit. The expression levels of mRNA for miR-155, NF-κB and its subunit NF-κB-p65 were assessed by q-PCR.

RESULTS

The results showed that compared with normal control CD14+ monocytes, the expression levels of miR-155, NF-κB and NF-κB-p65, TLR4, MyD88 and IL-6, TNF-α were increased, while expression levels of SOCS1 were decreased in CD14+ monocytes from psoriatic patients. Enhanced cell proliferation and oxidation were also observed in CD14+ monocytes from psoriatic patients. Inhibition of miR-155 partially corrected the abnormalities of cell proliferation and expression levels of biomarkers mentioned above in CD14+ monocytes from psoriatic patients. Inhibitions of both TLR4 pathway and miR-155 further corrected abnormalities of proliferation and the above biomarkers in CD14+ monocytes from psoriatic patients.

CONCLUSION

These results suggest that increased expression levels of miR-155 contribute to CD14+ monocyte-mediated inflammation and oxidation in psoriasis via TLR4 pathway.

The curious case of miR-155 in SLE

Epigenetic modifications have been well documented in autoimmune diseases. MicroRNAs (miRNAs), in particular, have long intrigued scientists in the field of autoimmunity. Owing to its central role in the development of the immune system, microRNA-155 (miR-155) is deeply involved in systemic lupus erythematosus (SLE). Despite the advancements made in treating SLE, the disease still remains incurable. Therefore, recent attention has been drawn to the manipulation of epigenetics in the development of curative treatments. In fact, it is a widely held view that miRNA-targeted therapy is a new glimmer of hope in the treatment of autoimmune diseases. However, the duplicity of miRNAs should not be overlooked. A single miRNA can target several mRNAs, and some mRNAs may possess opposing functions. In this review, we highlight the role of miR-155 as a biomarker and review its functions in SLE patients and animal models while discussing possible reasons behind inconsistencies across studies.

Immunological Involvement of MicroRNAs in the Key Events of Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is an archetype autoimmune disease characterized by a myriad of immunoregulatory abnormalities that drives injury to multiple tissues and organs. Due to the involvement of various immune cells, inflammatory cytokines, and related signaling pathways, researchers have spent a great deal of effort to clarify the complex etiology and pathogenesis of SLE. Nevertheless, current understanding of the pathogenesis of SLE is still in the early stages, and available nonspecific treatment options for SLE patients remain unsatisfactory. First discovered in 1993, microRNAs (miRNAs) are small RNA molecules that control the expression of 1/3 of human genes at the post-transcriptional level and play various roles in gene regulation. The aberrant expression of miRNAs in SLE patients has been intensively studied, and further studies have suggested that these miRNAs may be potentially relevant to abnormal immune responses and disease progression in SLE. The aim of this review was to summarize the specific miRNAs that have been observed aberrantly expressed in several important pathogenetic processes in SLE, such as DCs abnormalities, overactivation and autoantibody production of B cells, aberrant activation of CD4⁺ T cells, breakdown of immune tolerance, and abnormally increased production of inflammatory cytokines. Our summary highlights a novel perspective on the intricate regulatory network of SLE, which helps to enrich our understanding of this disorder and ignite future interest in evaluating the molecular regulation of miRNAs in autoimmunity SLE.

The interaction between iNKT cells and B cells

Invariant natural killer T cells (iNKTs) bridge the innate immunity with the adaptive immunity and their interaction with B cells has been extensively studied. Here, we give a complete overview of these two cells, from their mechanism of interaction to clinical prospects and existing problems. In our introduction, we describe the relationship between iNKTs and B cells and explore the current research hotspots and future directions. We begin with how B cells interact and benefit from the innate and adaptive help of iNKTs. Next, we describe the multiple roles of these cells in infections, autoimmunity, and cancers. Lastly, we look into the potential immunotherapies that can be based on iNKTs and the possible treatments for infectious, autoimmune, and other diseases.

Sexual dimorphism, aging and immunity

Health and lifespan disparities between sexes are dependent on the immune responses. Men and women have different life styles which determine the environment, nutritional requirements and their interactions with the sex hormones. Sexual dimorphism in innate and adaptive immunity determines responses to infections and other environmental factors regulating health and diseases. Sex hormones regulate immune responses through the expression of receptors which differ for female and male hormones. Estrogen receptors are expressed in brain, lymphoid tissue cells and many immune cells while androgen receptors are limited in expression. Genetic, epigenetic factors and X chromosome linked immune function genes are important in enhanced adaptive immunity in females, leading to production of higher levels of antibodies compared to males. Different nutritional requirements and hormonal control of the mucosal microbiome and its function regulate mucosal immunity. Hormonal changes during various aspects of life and during aging control immune senescence. Evolutionarily, females have an advantage during young age when they are protected from infections by heightened immune reactivity though during aging that can lead to pathologies. Considering the sexual dimorphism in immunity, guidelines need to be established for sex-based treatments for optimal response.

Bioactive Plasma Mitochondrial DNA Is Associated With Disease Progression in Scleroderma-Associated Interstitial Lung Disease

OBJECTIVE

Systemic sclerosis-associated interstitial lung disease (SSc-ILD) is characterized by variable clinical outcomes, activation of innate immune pattern-recognition receptors (PRRs), and accumulation of α-smooth muscle actin (α-SMA)-expressing myofibroblasts. The aim of this study was to identify an association between these entities and mitochondrial DNA (mtDNA), an endogenous ligand for the intracellular DNA-sensing PRRs Toll-like receptor 9 (TLR-9) and cyclic GMP-AMP synthase/stimulator of interferon genes (cGAS/STING), which has yet to be determined.

METHODS

Human lung fibroblasts (HLFs) from normal donors and SSc-ILD explants were treated with synthetic CpG DNA and assayed for α-SMA expression and extracellular mtDNA using quantitative polymerase chain reaction for the human MT-ATP6 gene. Plasma MT-ATP6 concentrations were evaluated in 2 independent SSc-ILD cohorts and demographically matched controls. The ability of SSc-ILD and control plasma to induce TLR-9 and cGAS/STING activation was evaluated with commercially available HEK 293 reporter cells. Plasma concentrations of type I interferons (IFNs), interleukin-6 (IL-6), and oxidized DNA were measured using electrochemiluminescence and enzyme-linked immunosorbent assay-based methods. Extracellular vesicles (EVs) precipitated from plasma were evaluated for MT-ATP6 concentrations and proteomics via liquid chromatography mass spectrometry.

RESULTS

Normal HLFs and SSc-ILD fibroblasts developed increased α-SMA expression and MT-ATP6 release following CpG stimulation. Plasma mtDNA concentrations were increased in the 2 SSc-ILD cohorts, reflective of ventilatory decline, and were positively associated with both TLR-9 and cGAS/STING activation as well as type I IFN and IL-6 expression. Plasma mtDNA was not oxidized and was conveyed by EVs displaying a proteomics profile consistent with a multicellular origin.

CONCLUSION

These findings demonstrate a previously unrecognized connection between EV-encapsulated mtDNA, clinical outcomes, and intracellular DNA-sensing PRR activation in SSc-ILD. Further study of these interactions could catalyze novel mechanistic and therapeutic insights into SSc-ILD and related disorders.

Bacteroides fragilis alleviates the symptoms of lupus nephritis via regulating CD1d and CD86 expressions in B cells

Emerging evidences indicated that the dysbiosis of microbiota was related to the onset of systemic lupus erythematosus (SLE). Bacteroides fragilis (B. fragilis) ATCC 25285, a human commensal, was discovered to improve inflammatory diseases. However, whether B. fragilis (ATCC 25285) has the beneficial effects on the treatment of lupus nephritis has still remained elusive. In the present study, oral treatment with B. fragilis (ATCC 25285) ameliorated the activity of MRL/lpr mice, including decreased levels of autoantibodies and symptoms of lupus nephritis. Furthermore, we demonstrated that treatment with B. fragilis (ATCC 25285) could promote CD1d expression in B cells by Est-1 pathway, while inhibit CD86 expression via SHP-2 signaling pathway to repair the immune response of B cells in MRL/lpr mice. In addition, our findings revealed a possible role of treatment with B. fragilis (ATCC 25285) in relieving intestinal inflammation in MRL/lpr mice. Meanwhile, it was uncovered that B. fragilis (ATCC 25285) restored the Th17/Treg balance in MRL/lpr mice that was consistent with the role of B. fragilis in other autoimmune diseases. Overall, the current study may highlight the potential application of B. fragilis (ATCC 25285) to treat manifestations of SLE in high-risk individuals.

Neutrophil extracellular traps activate lung fibroblast to induce polymyositis-related interstitial lung diseases via TLR9-miR-7-Smad2 pathway

Excessive neutrophil extracellular trap (NET) formation may contribute to polymyositis (PM)‐associated interstitial lung diseases (ILD), but the underlying mechanism is not fully revealed. In this study, we found that NET accelerated the progression of ILD and promoted pulmonary fibrosis (PF) in vivo. miR‐7 expression was down‐regulated in lung tissue of PM group than control group, and NETs further decreased miR‐7 expression. TLR9 and Smad2 were up‐regulated in lung tissue of PM group than control group, and NETs further increased TLR9 and Smad2 expressions. In vitro experiments showed that PMA‐treated NETs accelerated the proliferation of LF and their differentiation into myofibroblast (MF), whereas DNase I decreased the promotion effect of NETs. Neutrophil extracellular trap components myeloperoxidase (MPO) and histone 3 also promoted the proliferation and differentiation of LF. In addition, we demonstrated that TLR9 involved in the regulation of NETs on LF proliferation and differentiation, and confirmed the interaction between miR‐7 and Smad2 in LF. Finally, miR‐7‐Smad2 pathway was confirmed to be involved in the regulation of TLR9 on LF proliferation and differentiation. Therefore, NETs promote PM‐related ILD, and TLR9‐miR‐7‐Smad2 signalling pathway is involved in the proliferation of LFs and their differentiation into MFs.

TLR9 signalling in HCV-associated atypical memory B cells triggers Th1 and rheumatoid factor autoantibody responses

BACKGROUND & AIMS

Hepatitis C virus (HCV) infection contributes to the development of autoimmune disorders such as cryoglobulinaemia vasculitis (CV). However, it remains unclear why only some individuals with HCV develop HCV-associated CV (HCV-CV). HCV-CV is characterized by the expansion of anergic CD19⁺CD27⁺CD21^low/- atypical memory B cells (AtMs). Herein, we report the mechanisms by which AtMs participate in HCV-associated autoimmunity.

METHODS

The phenotype and function of peripheral AtMs were studied by multicolour flow cytometry and co-culture assays with effector T cells and regulatory T cells in 20 patients with HCV-CV, 10 chronicallyHCV-infected patients without CV and 8 healthy donors. We performed gene expression profile analysis of AtMs stimulated or not by TLR9. Immunoglobulin gene repertoire and antibody reactivity profiles of AtM-expressing IgM antibodies were analysed following single B cell FACS sorting and expression-cloning of monoclonal antibodies.

RESULTS

The Tbet⁺CD11c⁺CD27⁺CD21^- AtM population is expanded in patients with HCV-CV compared to HCV controls without CV. TLR9 activation of AtMs induces a specific transcriptional signature centred on TNFα overexpression, and an enhanced secretion of TNFα and rheumatoid factor-type IgMs in patients with HCV-CV. AtMs stimulated through TLR9 promote type 1 effector T cell activation and reduce the proliferation of CD4⁺CD25^hiCD127^-/lowFoxP3⁺ regulatory T cells. AtM expansions display intraclonal diversity with immunoglobulin features of antigen-driven maturation. AtM-derived IgM monoclonal antibodies do not react against ubiquitous autoantigens or HCV antigens including NS3 and E2 proteins. Rather, AtM-derived antibodies possess rheumatoid factor activity and target unique epitopes on the human IgG-Fc region.

CONCLUSION

Our data strongly suggest a central role for TLR9 activation of AtMs in driving HCV-CV autoimmunity through rheumatoid factor production and type 1 T cell responses.

LAY SUMMARY

B cells are best known for their capacity to produce antibodies, which often play a deleterious role in the development of autoimmune diseases. During chronic hepatitis C, self-reactive B cells proliferate and can be responsible for autoimmune symptoms (arthritis, purpura, neuropathy, renal disease) and/or lymphoma. Direct-acting antiviral therapy clears the hepatitis C virus and eliminates deleterious B cells.

Increased cytoplasmatic expression of cancer immune surveillance receptor CD1d in anaplastic thyroid carcinomas

BACKGROUND

Anaplastic thyroid carcinomas are associated with rapid tumor growth, short survival time and without any promising therapy to improve the poor prognosis. In this study, expression of immunoregulative receptor CD1d and lymphocyte infiltration in different thyroid tumors as well as in healthy tissue were analyzed in order to find new targets for an immunotherapeutic approach.

METHODS

CD1d immunohistochemistry was performed in samples of 18 anaplastic, 17 follicular, 27 papillary, and 4 medullary thyroid carcinomas as well as in 19 specimens from normal thyroid tissue and additionally in 10 samples of sarcoma, seven malignant melanoma and three spindle-cell lung carcinoma. Furthermore, thyroid samples were stained with antibodies against CD3, CD20, CD56, CD68, and LCA in order to analyze lymphocyte infiltration.

RESULTS

For the first time CD1d receptor expression on normal thyroid tissue could be demonstrated. Moreover, anaplastic thyroid carcinomas showed significantly higher expression levels compared to other thyroid samples. Most astonishingly, CD1d expression disappeared from the cellular surface and was detected rather in the cytoplasm of anaplastic thyroid carcinoma cells. In addition, histologically similar tumors to anaplastic carcinoma like sarcoma and malignant melanoma revealed distinct CD1d staining patterns. Furthermore, infiltration of T cells, B cells, and macrophages in anaplastic thyroid carcinomas was different when compared to normal thyroid tissue and all other thyroid carcinomas.

CONCLUSIONS

Anaplastic thyroid carcinomas show significantly higher expression of CD1d, a receptor for NKT cells, which are subject of several anticancer therapy studies. These results may offer a novel approach to explore immunotherapeutic treatment options.

The Interaction Between Two Worlds: MicroRNAs and Toll-Like Receptors

MicroRNAs (miRNAs) are critical mediators of posttranscriptional regulation via their targeting of the imperfect antisense complementary regions of coding and non-coding transcripts. Recently, researchers have shown that miRNAs play roles in many aspects of regulation of immune cell function by targeting of inflammation-associated genes, including Toll-like receptors (TLRs). Besides this indirect regulatory role of miRNAs, they can also act as physiological ligands of specific TLRs and initiate the signaling cascade of immune response. In this review, we summarize the potential roles of miRNAs in regulation of TLR gene expression and TLR signaling, with a focus on the ability of miRNAs bind to TLRs.

Analysis of long noncoding RNAs for acute rejection and graft outcome in kidney transplant biopsies

AIM

To analyse long noncoding RNAs (lncRNA) in kidney transplant biopsies.

METHODS

Using a data mining approach, we constructed expression profiles in kidney transplant cohorts (n = 1105) from Gene Expression Omnibus. Integrative analysis of the lncRNAs with acute rejection (AR), T-cell-mediated acute rejection (TCMR) and graft loss were performed.

RESULTS

Six lncRNAs were identified as are associated with AR in the training and validating datasets, and with a risk score was generated with 3-lncRNAs that were predictive of graft loss (AUC = 0.73). MIR155HG is associated with AR, TCMR and graft loss. Plus it might be involved in several graft rejection and immune associated pathways.

CONCLUSION

Understanding the role of lncRNAs in AR and graft outcome in kidney transplant biopsies needs to be further investigated.

The potential role of Ets-1 and miR-326 in CD19+B cells in the pathogenesis of patients with systemic lupus erythematosus

OBJECTIVES

The aim of this study was to investigate the B cell-associated transcription factors, Ets-1 and microRNA, miR-326 in systemic lupus erythematosus (SLE) patients, and their correlation with the pathogenesis of SLE.

METHOD

A total of 44 SLE patients and 20 healthy controls were enrolled in this research, all patients fulfilled the American College of Rheumatology classification criteria for SLE. The mRNA expression of Ets-1 and miR-326 in CD19⁺B cells from SLE patients were examined by qRT-PCR. The percentages of CD19⁺CD138⁺plasma cells were analyzed by Flow cytometry.

RESULTS

We found decreased expression of Ets-1 mRNA in SLE patients compared with the healthy controls ([0.228 (0.145, 0.507)] vs [0.583 (0.452, 0.763)], p = 0.001),while increased expression of miR-326 mRNA in CD19⁺B cells SLE patients compared with the healthy controls([1.092 (0.457, 2.855)] vs [0.685 (0.274, 0.819)], p = 0.008). The percentage of CD19⁺CD138⁺plasma cells in SLE patients was higher than that of healthy controls (0.55 ± 0.21% vs 0.36 ± 0.21%, p = 0.002). Moreover, a negative correlation between expression of Ets-1 mRNA and miR-326 mRNA in CD19⁺B cells was detected (r = - 0.334, p = 0.027). A significant association between the occurrences of CD19⁺CD138⁺plasma cells and the levels of Ets-1 mRNA and miR-326 mRNA was observed (r = - 0.417, p = 0.005 and r = 0.482, p = 0.001, respectively).

CONCLUSIONS

Our results suggest that miR-326 might promote B cells differentiation by targeting Ets-1, a negative regulator of B cells differentiation and therefore participate in the pathogenesis of SLE.

Emerging roles of microRNAs in the metabolic control of immune cells

Immunometabolism is an emerging field that focuses on the role of cellular metabolism in the regulation of immune cells. Recent studies have revealed an intensive link between the metabolic state and the functions of immune cells. MicroRNAs (miRNAs) are small non-coding, single-stranded RNAs generally consisting of 18-25 nucleotides that exert crucial roles in regulating gene expression at the posttranscriptional level. Although the role of miRNAs in immune regulation has long been recognized, their roles in immunometabolism have not yet been well established. Over the past decade, increasing studies have proven that miRNAs are intensively involved in the metabolic control of immune cells including macrophages, T cells, B cells and dendritic cells. In this review, we highlight recent emerging findings in the miRNA-mediated metabolic control of immune cells.

MicroRNA-326 Upregulates B Cell Activity and Autoantibody Production in Lupus Disease of MRL/lpr Mice

B cells are recognized as key participants in various autoimmune diseases, including systemic lupus erythematosus (SLE). Although sets of transcription factors and cytokines are known to regulate B cell differentiation, the roles of microRNAs are poorly understood. Our previous study proved that microRNA-326 (miR-326) was markedly upregulated in SLE patients; however, the biological function of miR-326 during SLE pathogenesis remained unknown. In this study, we found that miR-326 overexpression in MRL/lpr mice led to B cell hyperactivity and severe SLE. Moreover, E26 transformation-specific-1 (Ets-1), a negative regulator of B cell differentiation, was identified as a target of miR-326. Therefore, a novel mechanism has been found in which the elevated miR-326 in B cells of SLE promotes plasmablast development and antibody production through downregulation of Ets-1.

TLR9 (Toll-Like Receptor 9) Agonist Suppresses Angiogenesis by Differentially Regulating VEGFA (Vascular Endothelial Growth Factor A) and sFLT1 (Soluble Vascular Endothelial Growth Factor Receptor 1) in Preeclampsia

Preeclampsia is a common pregnancy-specific disorder characterized by elevated blood pressure and proteinuria. Activation of the maternal immune system and impaired placental angiogenesis are thought to contribute to the pathogenesis of preeclampsia. TLR9 (Toll-like receptor 9) plays a role in innate immunity, defending the organism against infection. The purpose of this study was to determine whether TLR9 inhibits angiogenesis at the fetomaternal interface under conditions of preeclampsia. We confirmed the downregulation of VEGFA (vascular endothelial growth factor A) and upregulation of TLR9 and sFLT1 (soluble vascular endothelial growth factor receptor 1) in placentas from preeclamptic women. Then, we established a mouse model with preeclampsia-like symptoms using the synthetic TLR9 agonist CpG (cytidine-phosphate-guanosine)-ODN (oligodeoxynucleotide; ODN1826). We observed the downregulation of VEGFA and the upregulation of sFLT1 in placentas from the preeclampsia-like animal model and in trophoblasts treated with CpG-ODN (ODN2006). In addition, silencing TLR9 promoted the migration and invasion of HTR8/SVneo cells. In conclusion, TLR9 is capable of robustly suppressing angiogenesis by differentially regulating the expression of VEGFA and sFLT1 at the fetomaternal interface, potentially contributing to the development of preeclampsia.

MicroRNA-155-at the Critical Interface of Innate and Adaptive Immunity in Arthritis

MicroRNAs (miRNAs) are small non-coding RNAs that fine-tune the cell response to a changing environment by modulating the cell transcriptome. miR-155 is a multifunctional miRNA enriched in cells of the immune system and is indispensable for the immune response. However, when deregulated, miR-155 contributes to the development of chronic inflammation, autoimmunity, cancer, and fibrosis. Herein, we review the evidence for the pathogenic role of miR-155 in driving aberrant activation of the immune system in rheumatoid arthritis, and its potential as a disease biomarker and therapeutic target.

Anti-inflammatory effects of curcumin are associated with down regulating microRNA-155 in LPS-treated macrophages and mice

CONTEXT

The natural polyphenolic compound curcumin has been proved to modulate innate immune responses and possess anti-inflammatory properties. Nevertheless, the mechanism remains poorly understood, particularly regarding curcumin-regulated miRNAs under inflammatory response.

OBJECTIVE

This study investigates the role of miRNA-155 in the effects of curcumin on inflammatory response in cell and a mouse model.

MATERIALS AND METHODS

The anti-inflammatory activity of curcumin (5, 10 and 15 μM, 2 h) in lipopolysaccharide (LPS, 200 ng/mL)-induced cells were measured by quantitative PCR. The animals were treated orally by 20 mg/kg curcumin for 3 days before an LPS intraperitoneal injection (10 mg/kg, 16 h). MicroRNA (miRNA) expression and the underlying molecular mechanisms were assessed using transfection technique and western blotting.

RESULTS AND DISCUSSION

Curcumin efficiently inhibited LPS-induced cytokines (TNF-α, IL-6) and microRNA-155 (miR-155) expression (p < 0.05) without affecting the normally growth of Raw264.7 and THP-1 cells (IC₅₀ 21.8 and 22.3 μM at 48 h, respectively). Moreover, the levels of cytokines were suppressed by curcumin in miR-155 mimics transfected cells (p < 0.05). A blockade of PI3K/AKT signalling pathways resulted in a decreased level of miR-155 (p < 0.05). Curcumin effectively protected mice from sepsis as evidenced by decreasing histological damage, reducing AST (352.0 vs 279.3 U/L), BUN (14.8 vs 10.8 mmol/L) levels and the proportion of macrophages in spleen (31.1% vs 13.5%). MicroRNA-155 level and cytokines were also reduced in curcumin-treated mice (p < 0.05).

CONCLUSIONS

Curcumin's ability to suppress LPS-induced inflammatory response may be due to the inhibition of miR-155.

TLR-Induced SMPD3 Defects Enhance Inflammatory Response of B Cell and Macrophage in the Pathogenesis of SLE

B lymphocyte and macrophages may contribute to SLE pathogenesis through cytokine production after TLR stimulation. Emerging evidences suggested that defects of sphingolipid metabolism were responsible for SLE pathogenesis. However, it is not clear whether these defects exist in B cells and macrophages under SLE condition and whether TLR signalling pathway was related to the dysfunction of sphingolipid metabolism in SLE. Here, we demonstrated that the enzymes involved in the sphingolipid metabolism expressed abnormally in B cells from SLE patients and lupus-prone mice. Moreover, we found that TLR signalling induced the abnormal expression of sphingomyelin phosphodiesterase 3 (SMPD3), sphingosine-1-phosphate phosphatase 2 (SGPP2), ceramide kinase (CERK) and UDP glycosyltransferase 8 (UGT8), which were involved in sphingolipid metabolism. TLR signalling also induced the transportation of SMPD3 from Golgi apparatus. Furthermore, the dysfunction of SMPD3 enhanced TLR-induced inflammatory response of B cells and macrophages in turn. Thus, these findings provide an innovative direction and a new target for research and treatment of SLE.

miRNA meets plasma cells "How tiny RNAs control antibody responses"

We review the importance of small non-coding microRNAs for the generation of germinal center B cells and their differentiation in antibody-secreting plasma cells. In the last part, we briefly elucidate the role of microRNAs in some plasma cell disorders.

Genome-Wide Identification of Target Genes for the Key B Cell Transcription Factor Ets1

Background

The transcription factor Ets1 is highly expressed in B lymphocytes. Loss of Ets1 leads to premature B cell differentiation into antibody-secreting cells (ASCs), secretion of autoantibodies, and development of autoimmune disease. Despite the importance of Ets1 in B cell biology, few Ets1 target genes are known in these cells.

Results

To obtain a more complete picture of the function of Ets1 in regulating B cell differentiation, we performed Ets1 ChIP-seq in primary mouse B cells to identify >10,000-binding sites, many of which were localized near genes that play important roles in B cell activation and differentiation. Although Ets1 bound to many sites in the genome, it was required for regulation of less than 5% of them as evidenced by gene expression changes in B cells lacking Ets1. The cohort of genes whose expression was altered included numerous genes that have been associated with autoimmune disease susceptibility. We focused our attention on four such Ets1 target genes Ptpn22, Stat4, Egr1, and Prdm1 to assess how they might contribute to Ets1 function in limiting ASC formation. We found that dysregulation of these particular targets cannot explain altered ASC differentiation in the absence of Ets1.

Conclusion

We have identified genome-wide binding targets for Ets1 in B cells and determined that a relatively small number of these putative target genes require Ets1 for their normal expression. Interestingly, a cohort of genes associated with autoimmune disease susceptibility is among those that are regulated by Ets1. Identification of the target genes of Ets1 in B cells will help provide a clearer picture of how Ets1 regulates B cell responses and how its loss promotes autoantibody secretion.

Decreased CD1d level is associated with CD86 over-expression in B cells from systemic lupus erythematosus

The disorder of B cells is one of the hallmarks of systemic lupus erythematosus (SLE). The activation state indicated by CD86 of B cells from SLE is well known, while the defect of regulatory B cells mediated by CD1d is also responsible for the process of SLE. In the present study, we focused on the relationship between B cell activation mediated by CD86 and B cell regulatory function mediated by CD1d. Our results showed that the level of CD1d in B cells was decreased during the early stages of B6.MRLlpr SLE mice and imiquimod-treated (IMQ-treated) mice, while the level of CD86 was significantly increased at the late stage. Moreover, the expression of CD1d showed a significantly negative correlation with CD86 level in B cells from IMQ-treated mice (r = -05741; P = 0.0022), B6.MRLlpr mice (r = -0.7091; P = 0.0268), and SLE patients (r = -0.4125; P = 0.0404). The in vivo and in vitro experiments with splenocytes demonstrated that CD1d signaling pathway could inhibit toll-like receptor 7 (TLR7)-induced CD86 expression of B cells. Further studies showed that this relationship also affected antibody production. Thus, our results confirmed the association of CD1d and CD86 levels in B cells from SLE, and demonstrated the importance to preserve the immunoregulatory function of B cells mediated by CD1d in the progression of SLE.

The role of microRNAs in the pathogenesis of autoimmune diseases

MicroRNAs (miRNAs) are single-stranded, endogenous non-coding small RNAs, ranging from 18 to 25 nucleotides in length. Growing evidence suggests that miRNAs are essential in regulating gene expression, cell development, differentiation and function. Autoimmune diseases are a family of chronic systemic inflammatory diseases. Recent findings on miRNA expression profiles have been suggesting their role as biomarkers in autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis and Sjögren's syndrome. In this review, we summarize the characteristics of miRNAs and their functional role in the immune system and autoimmune diseases including systemic lupus erythematosus, primary Sjögren's syndrome, rheumatoid arthritis, systemic sclerosis, multiple sclerosis and psoriasis; moreover, we depict the advantages of miRNAs in modern diagnostics.

Contribution of MicroRNAs to autoimmune diseases

MicroRNAs are a class of evolutionarily conserved, short non-coding RNAs that post-transcriptionally modulate the expression of multiple target genes. They are implicated in almost every biological process, including pathways involved in immune homeostasis, such as immune cell development, central and peripheral tolerance, and T helper cell differentiation. Alterations in miRNA expression and function can lead to major dysfunction of the immune system and mediate susceptibility to autoimmune disease. Here, we discuss the role of miRNAs in the maintenance of immune tolerance to self-antigens and the gain or loss of miRNA functions on tissue inflammation and autoimmunity.

High-dose dexamethasone corrects impaired myeloid-derived suppressor cell function via Ets1 in immune thrombocytopenia

Myeloid-derived suppressor cells (MDSCs) are heterogeneous immature cells and natural inhibitors of adaptive immunity. In this study, the MDSC population was evaluated in adult patients with primary immune thrombocytopenia (ITP), where cell-mediated immune mechanisms are involved in platelet destruction. Our data demonstrated that both the numbers and suppressive functions of MDSCs were impaired in the peripheral blood and spleens of patients with ITP compared with healthy control patients. High-dose dexamethasone (HD-DXM) treatment rescued MDSC numbers in patients with ITP. And DXM modulation promoted the suppressive function of MDSCs induced in vitro. Moreover, the expression of interleukin 10 and transforming growth factor β was significantly upregulated in DXM-modulated MDSCs compared with the unmodulated cultures. DXM-modulated MDSCs inhibited autologous CD4(+)T-cell proliferation and significantly attenuated cytotoxic T lymphocyte-mediated platelet lysis, further indicating enhanced control over T-cell responses. Elevated expression of the transcription factor Ets1 was identified in DXM-modulated MDSCs. Transfection of Ets-1 small interfering RNA efficiently blocked regulatory effects of MDSCs, which almost offset the augmentation of MDSC function by DXM. Meanwhile, splenocytes from CD61 knockout mice immunized with CD61(+)platelets were transferred into severe combined immunodeficient (SCID) mouse recipients (C57/B6 background) to induce a murine model of severe ITP. We passively transferred the DXM-modulated MDSCs induced from bone marrow of wild-type C57/B6 mice into the SCID mouse recipients, which significantly increased platelet counts in vivo compared with those receiving splenocyte engraftment alone. These findings suggested that impaired MDSCs are involved in the pathogenesis of ITP, and that HD-DXM corrected MDSC functions via a mechanism underlying glucocorticoid action and Ets1.