Down-regulation of A20 mRNA expression in peripheral blood mononuclear cells from patients with systemic lupus erythematosus

cGAS-STING pathway in systemic lupus erythematosus: biological implications and therapeutic opportunities

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway has been identified as a significant modulator of inflammation in various clinical contexts, including infection, cellular stress, and tissue injury. The extensive participation of the cGAS-STING pathway can be attributed to its ability to detect and control the cellular reaction to DNAs originating from both microorganisms and hosts. These DNAs are well recognized as molecules linked with potential risks. At physiological levels, the STING signaling system exhibits protective effects. However, prolonged stimulation of this pathway contributes to autoimmune disorder pathogenesis. The present paper provides an overview of the activation mechanism of the cGAS-STING signaling pathways and their associated significant functions, as well as therapeutic interventions in the context of systemic lupus erythematosus (SLE). The primary objective is to enhance our comprehension of SLE and facilitate more effective diagnosis and treatment strategies for this condition.

Down-regulation of A20 mRNA expression in peripheral blood mononuclear cells from MDS patients

Myelodysplastic syndrome (MDS) is characterized by activated inflammatory signaling and affects prognosis. Targeting inflammatory signaling may provide a way to treat the disease. We were curious whether there were changes in A20 in peripheral blood mononuclear cells (PBMC) of MDS patients. Therefore, we conducted a study with 60 clinical samples, including 30 MDS patients and 30 healthy controls. All patients with MDS were diagnosed and classified according to the criteria of the 2016 World Health Organization. The study was performed in accordance with the guidelines of the Declaration of Helsinki. Using Quantitative Real-Time RT-PCR, we discovered that A20 mRNA expression in PBMC of the MDS group was significantly lower than that in the control group (P < 0.001). Additionally, using Luminex Liquid Suspension Chip, we observed elevated plasma levels of pro-inflammatory IL-8 and TNF-α in the MDS group compared to the healthy control group (P < 0.001). We did not find a significant correlation between A20 mRNA and clinical characteristics (age, sex, concentration of hemoglobin, neutrophils count, platelets count, percent of blasts, and WHO classification) of the patients, nor between A20 mRNA and plasma cytokines (data not shown). Our study found down-regulated of A20 and increased levels of pro-inflammatory cytokines in the peripheral blood of MDS patients, providing further evidence for the activation of inflammatory signals in MDS.

A20 in Kidney Transplantation and Autoimmunity

A20, the central inhibitor of NFκB, has multiple anti-inflammatory properties, making it an interesting target in kidney autoimmune disease and transplant biology. It has been shown to be able to inhibit inflammatory functions in macrophages, dendritic cells, T cells, and B cells in various ways, leading to less tissue damage and better graft outcomes. In this review, we will discuss the current literature regarding A20 in kidney transplantation and autoimmunity. Future investigations on animal models and in existing immunosuppressive therapies are needed to establish A20 as a therapeutic target in kidney transplantation and autoimmunity. Cell-based therapies, modified viruses or RNA-based therapies could provide a way for A20 to be utilized as a promising mediator of inflammation and tissue damage.

A prospective cohort study on serum A20 as a prognostic biomarker of aneurysmal subarachnoid hemorrhage

BACKGROUND

A20 may be a neuroprotective factor. Herein, we aimed to investigate whether serum A20 levels were associated with disease severity, delayed cerebral ischemia (DCI), and outcome after aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

In this prospective cohort study containing 112 aSAH patients and 112 controls, serum A20 levels were quantified. At 90 d poststroke, Modified Rankin Scale (MRS) scores ≥3 were defined as a poor outcome. All correlations and associations were assessed using multivariate analysis.

RESULTS

Compared with controls, there was a significant elevation of serum A20 levels in patients (median 123.7 pg/mL vs. 25.8 pg/mL; P<0.001). Serum A20 levels were independently correlated with Hunt-Hess scores (β 9.854; 95% confidence interval [95% CI] 2.481-17.227, P=0.009) and modified Fisher scores (β 10.349, 95% CI 1.273-19.424, P=0.026). Independent associations were found between serum A20 levels and poor outcome (odds ratio [OR] 1.015, 95% CI 1.000-1.031, P=0.047) and DCI (OR 1.018, 95% CI 1.001-1.035, P=0.042). Areas under the curve for predicting poor outcome and DCI were 0.771 (95% CI 0.682-0.845) and 0.777 (95% CI 0.688-0.850), respectively. Serum A20 levels ≥128.15 pg/mL predicted poor outcome, with a sensitivity of 73.9% and specificity of 74.2%, and A20 levels ≥160.55 pg/mL distinguished the risk of DCI with 65.5% sensitivity and 89.2% specificity. Its ability to predict poor outcome and DCI was similar to those of Hunt-Hess scores and modified Fisher scores (both P>0.05).

CONCLUSION

Enhanced serum A20 levels are significantly associated with stroke severity and poor clinical outcome after aSAH, implying that serum A20 may be a potential prognostic biomarker for aSAH.

Kdm5a promotes B cell activation in systemic lupus erythematosus via downregulation of A20 by histone modification

Systemic lupus erythematosus (SLE) is a classic autoimmune connective tissue disease, which leads to multiple organ system injury. Tumor necrosis factor-induced protein 3 (TNFAIP3), generally called A20, has been documented to go together with the development of SLE. However, the role and mechanism of A20 in the progression of SLE are still unrevealed. In our study, A20 was downregulated in B cells from SLE patients and B cell responsiveness was significantly elevated in SLE patients. Overexpression of A20 restrained the proliferation and induced the apoptosis of B cells. Additionally, trimethylation of histone H3 Lysine 4 (H3K4me3) was decreased in the A20 promoter of SLE B cells. Lysine demethylase 5 A (Kdm5a) was significantly increased in B cells from SLE patients and negatively correlated with A20 expression. Further, Kdm5a knockdown increased the H3K4me3 level and A20 expression. More importantly, Kdm5a promoted the proliferation and inhibited the apoptosis of B cells in SLE via downregulation of A20. In general, Kdm5a promoted the proliferation and inhibited the apoptosis of B cells in SLE via downregulation of A20 by decreasing H3K4me3 enrichment level in the A20 promoter, suggesting a novel mechanism underlying SLE progression, and providing a promising therapeutic target for SLE. AVAILABILITY OF DATA AND MATERIALS: All data generated or analyzed during this study are included in this published article and its additional files.

Overexpression of the ubiquitin-editing enzyme A20 in the brain lesions of Multiple Sclerosis patients: moving from systemic to central nervous system inflammation

Multiple Sclerosis (MS) is a chronic demyelinating disease of the central nervous system (CNS) in which inflammation plays a key pathological role. Recent evidences showed that systemic inflammation induces increasing cell infiltration within meninges and perivascular spaces in the brain parenchyma, triggering resident microglial and astrocytic activation. The anti-inflammatory enzyme A20, also named TNF associated protein 3 (TNFAIP3), is considered a central gatekeeper in inflammation and peripheral immune system regulation through the inhibition of NF-kB. The TNFAIP3 locus is genetically associated to MS and its transcripts is downregulated in blood cells in treatment-naïve MS patients. Recently, several evidences in mouse models have led to hypothesize a function of A20 also in the CNS. Thus, here we aimed to unveil a possible contribution of A20 to the CNS human MS pathology. By immunohistochemistry/immunofluorescence and biomolecular techniques on post-mortem brain tissue blocks obtained from control cases (CC) and progressive MS cases, we demonstrated that A20 is present in CC brain tissues in both white matter (WM) regions, mainly in few parenchymal astrocytes, and in grey matter (GM) areas, in some neuronal populations. Conversely, in MS brain tissues, we observed increased expression of A20 by perivascular infiltrating macrophages, resident-activated astrocytes, and microglia in all the active and chronic active WM lesions. A20 was highly expressed also in the majority of active cortical lesions compared to the neighboring areas of normal-appearing grey matter (NAGM) and control GM, particularly by activated astrocytes. We demonstrated increased A20 expression in the active MS plaques, particularly in macrophages and resident astrocytes, suggesting a key role of this molecule in chronic inflammation.

Preserving immune homeostasis with A20

A20/TNFAIP3 is a TNF induced gene that plays a profound role in preserving cellular and organismal homeostasis (Lee, et al., 2000; Opipari etal., 1990). This protein has been linked to multiple human diseases via genetic, epigenetic, and an emerging series of patients with mono-allelic coding mutations. Diverse cellular functions of this pleiotropically expressed protein include immune-suppressive, anti-inflammatory, and cell protective functions. The A20 protein regulates ubiquitin dependent cell signals; however, the biochemical mechanisms by which it performs these functions is surprisingly complex. Deciphering these cellular and biochemical facets of A20 dependent biology should greatly improve our understanding of murine and human disease pathophysiology as well as unveil new mechanisms of cell and tissue biology.

Abnormal miR-214/A20 expression might play a role in T cell activation in patients with aplastic anemia

Aberrant T cell activation is a major cause of aplastic anemia (AA) pathogenesis. Recent studies have shown that miRNAs regulate T cell activation and are involved in AA. A previous study found that miR-214 was significantly up-regulated upon T cell activation in a CD28-dependent fashion by targeting PTEN. However, the expression characteristics of miR-214 and its target genes in AA have not been defined. In this study, target genes for miR-214 were predicted and confirmed by bioinformatics and luciferase reporter assays. The expression levels of miR-214 and target genes were detected in 36 healthy individuals and 35 patients with AA in peripheral blood mononuclear cells by real-time quantitative reverse transcriptase-polymerase chain reaction. Bioinformatics and luciferase reporter assays identified that miR-214 could bind to the A20 3' untranslated regions. Significantly increased miR-214 and the decreased A20 expression level were detected in the AA patients compared with the healthy group. In addition, significantly increased miR-214 was found in non-severe aplastic anemia compared with severe aplastic anemia patients. These results suggested that the A20 gene was a potential target of miR-214, and elevated miR-214 might medicate T cell activation at least in part by regulating A20 expression in AA. We firstly confirmed that miR-214 regulated A20 expression, and aberrant miR-214/A20 expression might contribute to immunopathology in AA. The miR-214 expression might be used as a potential biomarker that assisted in diagnosing AA severity.

Full high-throughput sequencing analysis of differences in expression profiles of long noncoding RNAs and their mechanisms of action in systemic lupus erythematosus

Background

The specific function of long noncoding RNAs (lncRNAs) in systemic lupus erythematosus (SLE) and the mechanism of their involvement in related pathological changes remain to be elucidated, so, in this study, we analyzed the differences in the expression profiles of lncRNAs and their mechanisms of action in SLE using full high-throughput sequencing, bioinformatics, etc. methods.

Methods

We used high-throughput sequencing to detect differences in the expression profiles of lncRNAs, miRNAs, and mRNAs in PBMCs from patients with SLE at the genome-wide level. Next, we predicted target genes of 30 lincRNAs (long intergenic noncoding RNAs) by constructing a coexpression network of differential lincRNAs and mRNAs and identified the role of lincRNAs. Then, we analyzed the coexpression network of 23 optimized lincRNAs and their corresponding 353 miRNAs, evaluated the cis- and trans-effects of these lincRNAs, and performed GO and KEGG analyses of target genes. We also selected 8 lincRNAs and 2 newly discovered lncRNAs for q-PCR validation and lncRNA–miRNA–mRNA analysis. Finally, we also analyzed respectively the relation between lncRNAs and gender bias in SLE patients using RT-qPCR, the relation between Systemic Lupus Erythematosus Disease Activity Index score and the “IFN signature” using ELISA, and the relation between the differential expression of lncRNAs and a change in the number of a cell type of PBMCs in SLE patients using RT-qPCR.

Results

The profiles of 1087 lncRNAs, 102 miRNAs, and 4101 mRNAs in PBMCs significantly differed between patients with SLE and healthy controls. The coexpression network analysis showed that the network contained 23 lincRNAs and 353 mRNAs. The evaluation of the cis- and trans-effects showed that the 23 lincRNAs acted on 704 target genes. GO and KEGG analyses of the target genes predicted the biological functions of the 23 lincRNAs. q-PCR validation showed 7 lincRNAs and 2 novel lncRNAs were identical to the sequencing results. The ceRNA network contained 7 validated lincRNAs, 15 miRNAs, and 155 mRNAs. In addition, the differential expression of lncRNAs may be gender dependent in SLE patients, SLE patients also exhibit a robust “IFN signature,” and PBMCs exhibiting differential expression of lncRNAs may be due to a change in the number of a cell type.

Conclusion

This work determined specific lncRNAs that play important biological functions in the pathogenesis of lupus and provided a new direction for diagnosis and treatment of disease.

Electronic supplementary material

The online version of this article (10.1186/s13075-019-1853-7) contains supplementary material, which is available to authorized users.

Association of TNFAIP3 and TNIP1 polymorphisms with systemic lupus erythematosus risk: A meta-analysis

OBJECT

With the development of GWAS, both TNFAIP3 and TNIP1 were revealed to be susceptibility genes of SLE. However, some other studies revealed no association between TNFAIP3, TNIP1 and SLE susceptibility. In order to estimate such association more precisely and systemically, a meta-analysis was conducted.

METHOD

Studies on the association between TNFAIP3 rs2230926, TNIP1 rs7708392 and SLE risk were carefully selected via searching 3 databases (Pubmed, Embase, and Web of Science). A fixed- or random-effect model was used according to the heterogeneity, and a subgroup analysis by ethnicity was also performed.

RESULTS

26 studies from 18 articles involving a total of 21,372 patients and 30,165 controls were analyzed for TNFAIP3 rs2230926. A significant association between the minor G allele of TNFAIP3 rs2230926 and SLE risk was found via a random-effect model (OR = 1.643, 95% CI = (1.462, 1.847), p < 0.01). In the subgroup analysis by ethnicity, significant correlations were also found in all Caucasians, Asians, and Africans (OR = 1.675, 95% CI = (1.353, 2.074), p < 0.01; OR = 1.738, 95% CI = (1.557, 1.940), p < 0.01; OR = 1.324, 95% CI = (1.029, 1.704), p < 0.05). As for TNIP1 rs7708392, 21 studies from 12 articles involving 24,716 cases and 32,200 controls were analyzed. A significant association of the minor C allele of TNIP1 rs7708392 and SLE risk was found via a random-effect model (OR = 1.247, 95% CI = (1.175, 1.323), p < 0.01). In the subgroup analysis by ethnicity, significant correlations were found in Caucasians, and Africans (OR = 1.317, 95% CI = (1.239, 1.401), p < 0.01; OR = 1.210, 95% CI = (1.108, 1.322), p < 0.01). However, there was no significant association in Asians (OR = 1.122, 95% CI = (0.953, 1.321), p > 0.05).

CONCLUSION

The minor G allele of TNFAIP3 rs2230926 was associated with increased risk of SLE in all Caucasians, Asians, and Africans. The minor C allele of TNIP1 rs7708392 was associated with the increased risk of SLE in Caucasians and Africans, while it was not associated with SLE susceptibility in Asians.

Decreased expression of A20 is associated with ocular Behcet's disease (BD) but not with Vogt-Koyanagi-Harada (VKH) disease

PURPOSE

A20 is a ubiquitously expressed and inducible cytosolic protein, which plays an important role in the negative regulation of inflammation and immunity. In this study, we investigated the role of A20 in Behcet's disease (BD) and Vogt-Koyanagi-Harada (VKH) disease.

METHODS

The levels of A20 in peripheral blood mononuclear cells (PBMCs) and dendritic cells (DCs) were detected in BD patients with active and inactive uveitis, VKH patients with active and inactive uveitis, and normal subjects, respectively, by real-time PCR. The effect of A20 silencing was performed by transduction of DCs with adenovirus containing an A20 shRNA vector. The effect of A20 silencing on the maturation of DCs was measured by flow cytometry. The effect of A20 silencing of DCs on cytokine production by DCs and CD4⁺ T cells was analysed by ELISA. The phosphorylation levels of JNK, p38 and ERK1/2 were detected by flow cytometry.

RESULTS

The expression of A20 was markedly decreased in PBMCs and DCs obtained from BD patients with active uveitis, but not in patients with VKH disease as compared with normal controls. Silencing of A20 significantly increased the levels of interleukin (IL)-1β and IL-6 and suppressed the expression of the anti-inflammatory cytokines IL-10 and IL-27. Downregulation of A20 also led to an increase in IL-17 production by CD4⁺ T cells. However, downregulation of A20 in DCs did not have an effect on cell surface markers such as CD40, CD80, CD83, CD86 and HLA-DR. Silencing of A20 caused an increased expression of phospho-JNK and phospho-MAPK p38 but not phospho-ERK1/2.

CONCLUSIONS

This study showed that the expression of A20 was decreased in BD patients with active uveitis but not in VKH disease. Decreased expression of A20 may lead to an enhanced activation of proinflammatory Th17 cells, causing a reactivation of BD.

A20/Tumor Necrosis Factor α-Induced Protein 3 in Immune Cells Controls Development of Autoinflammation and Autoimmunity: Lessons from Mouse Models

Immune cell activation is a stringently regulated process, as exaggerated innate and adaptive immune responses can lead to autoinflammatory and autoimmune diseases. Perhaps the best-characterized molecular pathway promoting cell activation is the nuclear factor-κB (NF-κB) signaling pathway. Stimulation of this pathway leads to transcription of numerous pro-inflammatory and cell-survival genes. Several mechanisms tightly control NF-κB activity, including the key regulatory zinc finger (de)ubiquitinating enzyme A20/tumor necrosis factor α-induced protein 3 (TNFAIP3). Single nucleotide polymorphisms (SNPs) in the vicinity of the TNFAIP3 gene are associated with a spectrum of chronic systemic inflammatory diseases, indicative of its clinical relevance. Mice harboring targeted cell-specific deletions of the Tnfaip3 gene in innate immune cells such as macrophages spontaneously develop autoinflammatory disease. When immune cells involved in the adaptive immune response, such as dendritic cells or B-cells, are targeted for A20/TNFAIP3 deletion, mice develop spontaneous inflammation that resembles human autoimmune disease. Therefore, more knowledge on A20/TNFAIP3 function in cells of the immune system is beneficial in our understanding of autoinflammation and autoimmunity. Using the aforementioned mouse models, novel A20/TNFAIP3 functions have recently been described including control of necroptosis and inflammasome activity. In this review, we discuss the function of the A20/TNFAIP3 enzyme and its critical role in various innate and adaptive immune cells. Finally, we discuss the latest findings on TNFAIP3 SNPs in human autoinflammatory and autoimmune diseases and address that genotyping of TNFAIP3 SNPs may guide treatment decisions.

TIPE2 expression is increased in peripheral blood mononuclear cells from patients with rheumatoid arthritis

We investigated the changes in mRNA and protein expression of tumor necrosis factor-α–induced protein 8-like 2 (TIPE2) and PEST-containing nuclear protein (PCNP) in peripheral blood lymphocytes from 54 patients with rheumatoid arthritis (RA) and the spleens of model mice with collagen-induced arthritis (CIA) to generate new ideas for clinical diagnosis and treatment. Expression levels of both TIPE2 and PCNP were higher in RA patients and CIA mice than in their respective controls. They were also higher in the 32 patients with active RA than in the 22 with inactive RA (P < 0.001 for both). After comprehensively treating patients with active RA with anti-inflammatory and antirheumatic drugs for 6 months, they were stable, and there was no difference in TIPE2 levels between the treated patients and those with inactive RA (P = 0.85). In addition, TIPE2 mRNA levels in peripheral blood correlated positively with PCNP (R² = 0.744, P = 0.001). The DAS28 score correlated positively with peripheral blood TIPE2 levels in the RA patients (R² = 0.945, P = 0.001). These findings suggest TIPE2 expression increases with the severity of RA.

TNFAIP3 downregulation mediated by histone modification contributes to T-cell dysfunction in systemic lupus erythematosus

Objective

TNF-α-induced protein 3 ( TNFAIP3 ) is one of the major SLE susceptibility genes involved in the regulation of inflammatory responses through modulation of the nuclear factor-κB (NF-κB) pathway. We aim to assess TNFAIP3 expression in CD4 + T cells and the molecular mechanism underlying TNFAIP3 regulation in the pathogenesis of SLE.

Methods

The expression and epigenetic regulation of TNFAIP3 in CD4 + T cells from SLE patients and normal controls (NCs) were investigated by RT-quantitative PCR, western blot and chromatin immunoprecipitation. The functional effect of TNFAIP3 was further evaluated by knockdown or overproduction of TNFAIP3 in CD4 + T cells from SLE patients and NCs.

Results

TNFAIP3 mRNA was significantly downregulated in the CD4 + T cells of SLE patients compared with NCs. The reduced expression of TNFAIP3 was associated with the reduction of H3K4me3 in the gene promoter region. Functional blockage of TNFAIP3 in normal CD4 + T cells using small interfering RNA increased the expression of IFN-γ and IL-17, but not IL-2, IL-4 and IL-5. Nevertheless, overexpression of TNFAIP3 in CD4 + T cells from SLE patients resulted in the suppression of IFN-γ and IL-17 production.

Conclusion

The downregulation of TNFAIP3 in CD4 + T cells of SLE was potentially regulated by demethylation of histone H3K4, which led to a decreased amount of H3K4me3 in the promoter of the TNFAIP3 gene. The dysregulation of TNFAIP3 in CD4 + T cells may contribute to the pathogenesis of SLE by overproduction of inflammatory cytokine IFN-γ and IL-17. TNFAIP3 may serve as a promising target for the treatment of SLE in clinical practice.

Comprehensive long non-coding RNA expression profiling reveals their potential roles in systemic lupus erythematosus

Long non-coding RNAs can regulate gene transcription, modulate protein function, and act as competing endogenous RNA. Yet, their roles in systemic lupus erythematosus remain to be elucidated. We determined the expression profiles of lncRNAs in T cells of SLE patients and healthy controls using microarrays. Up to 1935 lncRNAs and 1977 mRNAs were differentially expressed. QRT-PCR showed downregulated uc001ykl.1 and ENST00000448942 in SLE patients. Expression of uc001ykl.1 correlated with erythrocyte sedimentation rate (ESR) and C-reactive protein, whereas ENST00000448942 level correlated with ESR and anti-Sm antibodies. Short time-series expression miner analysis revealed some lncRNAs whose expressions might correlate with disease activity of SLE patients. Coding-non-coding gene coexpression analyses showed differential lncRNAs might operate via modulating expressions of their correlated, relevant mRNAs in SLE. Differential lncRNAs might also function through their ceRNAs. Our study established that the aberrant expression profiles of lncRNAs may play a role in SLE and thus warrant further investigation.

A new benzenediamine derivative modulates Toll-like receptors-induced myeloid dendritic cells activation and ameliorates lupus-like syndrome in MRLlpr/lpr mice

Modulators of the over-activation of myeloid dendritic cells (mDCs) by Toll-like receptors (TLRs) have an advantage in the treatment of systemic lupus erythematosus (SLE). This study was designed to evaluate the effects of FC-99, a novel benzenediamine derivative, on TLR-induced activation of mDCs, and to assess the efficacy of FC-99 in a murine model of SLE. In vitro, FC-99 inhibited the phenotypic (CD40 and MHC-II) and functional activation (IL-12 and CXCL10) of mDCs induced by TLR ligands. In vivo, MRLlpr/lpr mice displayed renal diseases associated with increased levels of proteinuria and immunoglobulin, which were ameliorated by FC-99. Enhanced accumulation and activation of mDCs in lymphoid organs was also impaired by FC-99. Additionally, FC-99 inhibited the activation of IκB-α and upregulated the expression of TNFα-induced protein 3 (TNFAIP3) in vitro and in vivo. These results indicate that FC-99 modulates TLR-induced activation of mDCs and ameliorates lupus-like syndrome in MRLlpr/lpr mice. This effect is closely associated with the inhibition of IκB-α and upregulation of TNFAIP3.

A20 Ameliorates Intracerebral Hemorrhage-Induced Inflammatory Injury by Regulating TRAF6 Polyubiquitination

Reducing excessive inflammation is beneficial for the recovery from intracerebral hemorrhage (ICH). Here, the roles and mechanisms of A20 (TNFAIP3), an important endogenous anti-inflammatory factor, are examined in ICH. A20 expression in the PBMCs of ICH patients and an ICH mouse model was detected, and the correlation between A20 expression and neurologic deficits was analyzed. A20 expression was increased in PBMCs and was negatively related to the modified Rankin Scale score. A20 expression was also increased in mouse perihematomal tissues. A20^-/- and A20-overexpressing mice were generated to further analyze A20 function. Compared with wild-type (WT) mice, A20^-/- and A20-overexpressing mice showed significant increases and decreases, respectively, in hematoma volume, neurologic deficit score, mortality, neuronal degeneration, and proinflammatory factors. Moreover, WT-A20^-/- parabiosis was established to explore the role of A20 in peripheral blood in ICH injury. ICH-induced damage, including brain edema, neurologic deficit score, proinflammatory factors, and neuronal apoptosis, was reduced in A20^-/- parabionts compared with A20^-/- mice. Finally, the interactions between TRAF6 and Ubc13 and UbcH5c were increased in A20^-/- mice compared with WT mice; the opposite occurred in A20-overexpressing mice. Enhanced IκBα degradation and NF-κB activation were observed in A20^-/- mice, but the results were reversed in A20-overexpressing mice. These results suggested that A20 is involved in regulating ICH-induced inflammatory injury in both the central and peripheral system and that A20 reduces ICH-induced inflammation by regulating TRAF6 polyubiquitination. Targeting A20 may thus be a promising therapeutic strategy for ICH.

Roles of A20 in autoimmune diseases

A20 (TNFAIP3), known to inhibit NF-κB function by deubiquitinating-specific NF-κB signaling molecules, has been found in many cell types of the immune system. Recent findings suggest that A20 is essential for the development and functional performance of dendritic cell, B cell, T cell and macrophage. A number of studies further demonstrate that these cells are crucial in the pathogenesis of autoimmune diseases, such as type 1 diabetes, systemic lupus erythematosus, inflammatory bowel disease, ankylosing arthritis, Sjögren's syndrome and rheumatoid arthritis. In this article, we focus on the recent advances on the roles of A20 in autoimmune diseases and discuss the therapeutic significance of these new findings.

Altered expression of A20 gene in peripheral blood mononuclear cells is associated with the progression of chronic hepatitis B virus infection

A20 is an important negative immune regulator but its role in chronic hepatitis B virus (HBV) infection is still unknown. This present study was to investigate the potential role of A20 gene in the progression of chronic HBV infection. A total of 236 chronic HBV patients were included and consisted of 63 hepatocellular carcinoma (HCC), 87 liver cirrhosis (LC) and 86 chronic hepatitis B (CHB). The mRNA level of A20 gene in peripheral blood mononuclear cells was determined using quantitative real-time polymerase chain reaction. Receptor operating characteristic curve (ROC) was performed to determine the diagnostic value of A20 mRNA in different stages of chronic HBV infection. A20 mRNA levels in all HBV patients were significantly higher than healthy controls (n=30), of whom HCC and LC patients showed higher A20 mRNA level than CHB patients. In CHB patients, A20 mRNA was closely associated with alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin. In LC patients, A20 mRNA was significantly associated with ALT, AST, albumin, haemoglobin and platelet. In HCC patients, elevated A20mRNA was also observed in patients with vascular invasion, liver cirrhosis and ascites, compared with those without. ROC analysis revealed that A20 mRNA could effectively discriminate LC from CHB, decompensated LC from compensated LC, and HCC from CHB. In conclusion, A20 mRNA expression in peripheral blood mononuclear cells was associated with dynamic progression of chronic HBV infection. A20 gene might be a potential biomarker to determine the different stages of chronic HBV infection.

A20 suppresses canonical Smad-dependent fibroblast activation: novel function for an endogenous inflammatory modulator

Background

The ubiquitin-editing cytosolic enzyme A20, the major negative regulator of toll-like receptor (TLR)-mediated cellular inflammatory responses, has tight genetic linkage with systemic sclerosis (SSc). Because recent studies implicate endogenous ligand-driven TLR signaling in SSc pathogenesis, we sought to investigate the regulation, role and mechanism of action of A20 in skin fibroblasts.

Method

A20 expression and the effects of forced A20 expression or siRNA-mediated A20 knockdown on fibrotic responses induced by transforming growth factor-ß (TGF-ß) were evaluated was evaluated in explanted human skin fibroblasts. Additionally, A20 regulation by TGF-ß, and by adiponectin, a pleiotropic adipokine with anti-fibrotic activity, was evaluated.

Results

In normal fibroblasts, TGF-ß induced sustained downregulation of A20, and abrogated its TLR4-dependent induction. Forced expression of A20 aborted the stimulation of collagen gene expression and myofibroblast transformation induced by TGF-ß, and disrupted canonical Smad signaling and Smad-dependent transcriptional responses. Conversely, siRNA-mediated knockdown of A20 enhanced the amplitude of fibrotic responses elicited by TGF-ß. Adiponectin, previously shown to block TLR-dependent fibrotic responses, elicited rapid and sustained increase in A20 accumulation in fibroblasts.

Conclusion

These results identify the ubiquitin-editing enzyme A20 as a novel endogenous mechanism for negative regulation of fibrotic response intensity. Systemic sclerosis-associated genetic variants of A20 that cause impaired A20 expression or function, combined with direct suppression of A20 by TGF-ß within the fibrotic milieu, might play a significant functional role in persistence of fibrotic responses, while pharmacological augmentation of A20 inhibitory pathway activity might represent a novel therapeutic strategy.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1118-7) contains supplementary material, which is available to authorized users.

C/EBP β mRNA expression is upregulated and positively correlated with the expression of TNIP1/TNFAIP3 in peripheral blood mononuclear cells from patients with systemic lupus erythematosus

CCAAT/enhancer-binding protein β (C/EBP β) has important roles in numerous signaling pathways. The expression of the majority of regulators and target gene products of C/EBP β, including tumor necrosis factor α-induced protein 3 (TNFAIP3) and TNFAIP3-interacting protein 1 (TNIP1), are upregulated in patients with systemic lupus erythematosus (SLE). The aim of the present study was to investigate whether C/EBP β expression is associated with SLE pathogenesis and correlates with TNIP1 and TNFAIP3 expression. Quantitative reverse transcription-polymerase chain reaction analysis was used to assess the expression of C/EBP β, TNIP1, and TNFAIP3 mRNA in peripheral blood mononuclear cells (PBMC) from 20 patients with SLE and 20 healthy controls. Spearman's rank test was used to determine the correlation between C/EBP β expression and SLE disease activity, and that between C/EBP β expression and TNIP1/TNFAIP3 expression in PBMCs from patients with SLE. C/EBP β mRNA expression was markedly increased in patients with SLE compared with healthy controls. The expression of C/EBP β was positively correlated with the SLE disease activity index and negatively correlated with the serum level of complement components C3 and C4. In addition, C/EBP β mRNA expression was increased in PBMCs from SLE patients that were positive for antinuclear, anti-Smith and anti-nRNP antibodies, compared with the antibody negative SLE patients. Furthermore, the mRNA expression levels of C/EBP β in patients with SLE was positively correlated with TNIP1 and TNFAIP3 expression. The results of the current study suggest that the increased expression of C/EBP β in PBMCs and the interaction between C/EBP β and TNIP1/TNFAIP3 may be involved in the pathogenesis of SLE.

Upregulation of the C/EBP β LAP isoform could be due to decreased TNFAIP3/TNIP1 expression in the peripheral blood mononuclear cells of patients with systemic lupus erythematosus

OBJECTIVES

We aimed to examine CCAAT/enhancer-binding protein β (C/EBP β), TNF-alpha-induced protein 3 (TNFAIP3), and TNFAIP3-interacting protein 1 (TNIP1) expression in peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematosus (SLE) patients to assess their relationship in SLE pathogenesis.

METHODS

C/EBP β, TNIP1, and TNFAIP3 expression was assessed in PBMCs from 20 SLE patients and 20 controls by western blotting. The correlation between C/EBP β/TNFAIP3/TNIP1 expression and SLE disease activity was determined by Spearman's rank. C/EBP β, TNIP1, and TNFAIP3 levels in THP-1 cells, THP-1 cells transfected with plasmids encoding TNFAIP3 shRNA, and THP-1 cells infected with lentiviral vectors encoding TNIP1 shRNA were assessed by western blotting.

RESULTS

C/EBP β LAP isoform expression was increased and LIP/TNFAIP3/TNIP1 expression was decreased in SLE patients. LAP expression was positively correlated with SLE disease activity; TNFAIP3 and TNIP1 expression was negatively correlated with SLE disease activity. LAP expression was increased in SLE patients with proteinuria and elevated anti-dsDNA antibody, as well as in THP-1 cells transfected with plasmids encoding TNFAIP3 shRNA and THP-1 cells infected with lentiviral vectors encoding TNIP1 shRNA.

CONCLUSIONS

C/EBP β/TNFAIP3/TNIP1 is associated with SLE activity. The upregulated expression of C/EBP β LAP could be caused by reduced TNFAIP3/TNIP1 expression.

Tumor necrosis factor α-induced protein-3 protects zinc transporter 8 against proinflammatory cytokine-induced downregulation

Zinc transporter 8 (ZnT8) is exclusively expressed in the pancreatic islet and is essential for insulin crystallization, hexamerization and secretion. Tumor necrosis factor α-induced protein-3 (TNFAIP3) is a zinc finger protein that serves a major role in the negative feedback regulation of NF-κB signaling in response to multiple stimuli, and is a central regulator of immunopathology. Although the role of TNFAIP3 in diabetes has been extensively studied, its effect on ZnT8 has not been fully elucidated. The present study aimed to verify whether proinflammatory cytokines, tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β), are able to affect ZnT8 expression in islet cells. In addition, the study aimed to determine the effect of TNFAIP3 overexpression on cytokine-altered ZnT8 activity, considering its effect on NF-κB signaling. Cell-based studies using NIT-1 cells overexpressing TNFAIP3 were used to assess the effect of cytokines on ZnT8 and NF-κB activation, as well as the effect of TNFAIP3 on ZnT8 expression. Western blot analysis and immunofluorescence staining were employed to determine the protein expression and NF-κB activation, respectively. The results indicated that cytokine stimulation led to TNFAIP3 upregulation, ZnT8 downregulation and NF-κB activation. Furthermore, TNFAIP3 overexpression protected ZnT8 from cytokine-induced downregulation. In conclusion, the current results suggest that inflammation or TNFAIP3 dysfunction may be involved in the pathogenesis of diabetes via ZnT8 expression, besides from islet cell apoptosis. In addition, restricting inflammation and enhancing TNFAIP3 expression may exert a positive effect in diabetes prevention, treatment and pancreatic cell transplantation.

Aberrant Low Expression of A20 in Tumor Necrosis Factor-α-stimulated SLE Monocytes Mediates Sustained NF-κB Inflammatory Response

The aberrantly activated monocytes and nuclear factor-kappaB (NF-κB) pathway contribute to the pathogenesis of systemic lupus erythematosus (SLE), and the aberrantly activated NF-κB is associated with defects in the anti-inflammatory A20 in SLE. However, whether SLE monocytes express A20 and whether the A20 expression under sustained proinflammatory stimulation is altered to contribute to the uncontrolled NF-κB inflammatory response are unclear. In this study, we found that the freshly isolated monocytes from SLE patients and healthy controls did not differ in expression levels of IL-1β, IκBα and A20. After TNF-α stimulation for 48 h, the monocytes from both groups expressed higher levels of IL-1β and IκBα than the monocytes without TNF-α treatment. Although the increased levels of NF-κB were observed in the nucleus of both the SLE and control monocytes after 24 h of TNF-α stimulation, the enhancement in SLE monocytes was significantly more robust than in the control monocytes. In addition, while the p-IκBα level in healthy monocytes was increased, the p-IκBα level in SLE monocytes was slightly decreased after TNF-α stimulation. Interestingly, after TNF-α treatment, the A20 expression in SLE monocytes was not markedly altered compared with the untreated SLE monocytes; moreover, the SLE monocytes expressed significantly lower A20 than healthy monocytes with TNF-α treatment at each time point. Results in this study demonstrate that TNF-α activates a significant NF-κB inflammatory response in SLE monocytes, which is at least partially mediated by the aberrantly low expression of A20 upon TNF-α stimulation, contributing to the prolonged inflammatory response in SLE.

Increased A20 mRNA Level in Peripheral Blood Mononuclear Cells is Associated With Immune Phases of Patients With Chronic Hepatitis B

The zinc finger protein A20 is a newly identified negative regulator of immune response and mediates signal pathway of NF-κB in liver inflammation. However, the role of A20 in the natural history of patients with chronic hepatitis B (CHB) has not been demonstrated. In this present study, we aimed to investigate the dynamic expression of A20 and determine the potential association of A20 in the progression of chronic hepatitis B virus infection.This retrospective study contained 136 patients with chronic hepatitis B and 30 healthy controls (HCs). The mRNA level of A20, TNF-α, NF-κB p65 and toll-like receptor (TLR) 4 in peripheral blood mononuclear cells (PBMCs) was determined using a relative quantitative real-time polymerase chain reaction. The hepatic A20 protein expression was determined by immunohistochemistry. Clinical and laboratory parameters were obtained.In the present study, the relative expression of A20 mRNA was significantly increased in CHB patients compared with HCs and was positively associated with alanine aminotransferase, aspartate aminotransferase, and total bilirubin. In CHB patients, the levels of A20 mRNA in the immune clearance (IC) phase and hepatitis B negative (ENH) phase were significantly higher than that in immune tolerance (IT) phase and low-replicative (LR) phase (P < 0.001). Furthermore, the A20 mRNA level was significantly correlated with TNF-α/ NF-κB p65/TLR4 mRNA levels in CHB patients. Of note, we reported that cutoff values of 4.19 and 3.97 for the level of A20 mRNA have significant power in discriminating IC from IT, and ENH from LR in CHB patients respectively.In conclusion, our results suggested that increased levels of A20 mRNA and protein contribute to disease progression of chronic hepatitis B virus infection.

Altered TNFAIP3 mRNA expression in peripheral blood mononuclear cells from patients with rheumatoid arthritis

The tumor necrosis factor α-induced protein-3 (TNFAIP3) gene functions in negative immunoregulation and its single-nucleotide polymorphisms (SNPs) are associated with rheumatoid arthritis (RA) disease. However, its expression level in immune cells from RA patients remains unclear. The aim of the present study was to investigate whether the expression of TNFAIP3 is changed in patients with RA. Reverse transcription-quantitative polymerase chain reaction analysis was used to determine TNFAIP3 mRNA expression in peripheral blood mononuclear cells (PBMCs) from patients with RA and healthy controls. TNFAIP3 expression was decreased in RA patients compared with the healthy controls. The expression level of the TNFAIP3 gene negatively correlated with the RA score, anti-cyclic citrullinated peptide (CCP) antibody levels and C-reactive protein levels. Furthermore, RA patients with positive results of anti-CCP antibodies had a lower expression of TNFAIP3 than those without anti-CCP antibodies. In conclusion, the present results suggest that the insufficient expression of the TNFAIP3 gene in PBMCs may correlate with the diagnosis of RA.

Let-7 miRNAs Modulate the Activation of NF-κB by Targeting TNFAIP3 and Are Involved in the Pathogenesis of Lupus Nephritis

TNFAIP3 is a ubiquitin-editing enzyme that negatively regulates multiple NF-κB signaling pathways and dysregulation of TNFAIP3 is related to systemic lupus erythematosus (SLE). Although there exists evidence indicating that microRNAs (miRNAs) modulate the expression of TNFAIP3, whether and how miRNAs regulate TNFAIP3 and contribute to lupus nephritis (LN) is still not well understood. In this study, we screened eleven selected miRNAs that potentially regulated TNFAIP3 expression by dual luciferase assay and found that Let-7 miRNAs repressed TNFAIP3 expression by targeting the 3′UTR of TNFAIP3 mRNA. Overexpression of Let-7 miRNAs led to increased phosphorylation and sustained degradation of IκBα and enhanced phosphorylation of p65 following TNFα stimulation and promoted SeV-induced production of cytokines in HEK293T cells. In addition, the expression of Let-7 miRNAs was significantly up-regulated, and TNFAIP3 level was remarkably down-regulated in samples from LN patients compared control samples. Our findings have uncovered Let-7-TNFAIP3-NF-κB pathway that is involved in LN and thus provided a potential target for therapeutic intervention.

Expression and Polymorphisms of Lysosome-Associated Protein Transmembrane 5 (LAPTM5) in Patients with Systemic Lupus Erythematosus in a Chinese Population

Lysosome-associated protein transmembrane 5 (LAPTM5) have been demonstrated a role in the prevention of lymphocyte hyperactivation, and its deficiency is involved in the immunological dysfunction of mouse models. The aim of this study was to detect mRNA expression of LAPTM5 in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE), and to assess association between LAPTM5 single nucleotide polymorphisms (SNPs) (rs10798801, rs4614309, rs1188348, and rs1188349) and SLE in a Chinese population. Real-time transcription-polymerase chain reaction analysis was used to determine expression of LAPTM5 mRNA in PBMCs from 132 patients with SLE and 62 healthy controls. LAPTM5 mRNA expression decreased in SLE patients (n = 71) compared with healthy controls (n = 58) (p = 3.68 × 10(-5)). The expression of LAPTM5 mRNA in SLE patients with lupus nephritis (LN) (n = 35) was lower than in those without LN (n = 36) (p = 0.004). The expression level of LAPTM5 correlated with serum total protein (r(s) = 0.41, p = 0.027) and negatively correlated with 24-h proteinuria (r(s) = -0.45, p = 0.027). LAPTM5 SNPs (rs10798801, rs4614309, rs1188348, and rs1188349) was also analyzed by restriction fragment length polymorphism (RFLP) in 380 SLE patients and 460 healthy controls. No significant difference in the genotype or allele frequencies for LAPTM5 SNPs was detected in 380 SLE patients and 460 healthy controls (p > 0.05). Substantially low frequency of GGAT haplotype was observed in SLE patients (p < 0.001). It is concluded that insufficient expression of LAPTM5 may take part in the pathogenesis of SLE and contribute to the severity of the disease, and none of LAPTM5 polymorphisms contributes significantly to SLE susceptibility in a Chinese population.

Decreased A20 mRNA and protein expression in peripheral blood mononuclear cells in patients with type 2 diabetes and latent autoimmune diabetes in adults

AIMS

A20 is a negative regulator of nuclear factor kappa B activation and the central gatekeeper in inflammation and immunity. While its role in type 1 diabetes has been widely studied, its expression level in immune cells from type 2 diabetes (T2D) and latent autoimmune diabetes in adult (LADA) patients remains unclear. This study aimed to clarify whether the expression of A20 is altered in patients with T2D or LADA.

METHODS

Quantitative real-time polymerase chain reaction and western blotting were utilized to determine the expression of A20 mRNA and protein respectively in peripheral blood mononuclear cells (PBMCs) from patients with T2D (n=36) or LADA (n=17) and sex- and age-matched healthy controls (n=34).

RESULTS

The mRNA and protein expression of A20 in PBMCs from T2D and LADA patients was significantly decreased compared with healthy controls (P<0.05). Furthermore, A20 mRNA and protein expression was significantly lower in newly diagnosed T2D patients (≤1 year since diagnosis) than in patients with a long T2D duration (>1 year since diagnosis) (P<0.05).

CONCLUSIONS

Our results suggest that decreased expression of A20 in PBMCs may be involved in the pathogenesis of diabetes, and targeting A20 may offer a potential therapeutic tool in the treatment of diabetes.

γδ T Cell-Mediated Immune Responses in Disease and Therapy

The role of γδ T cells in immunotherapy has gained specific importance in the recent years because of their prominent function involving directly or indirectly in the rehabilitation of the diseases. γδ T cells represent a minor population of T cells that express a distinct T cell receptor (TCR) composed of γδ chains instead of αβ chains. Unlike αβ T cells, γδ T cells display a restricted TCR repertoire and recognize mostly unknown non-peptide antigens. γδ T cells act as a link between innate and adaptive immunity, because they lack precise major histocompatibility complex (MHC) restriction and seize the ability to recognize ligands that are generated during affliction. Skin epidermal γδ T cells recognize antigen expressed by damaged or stressed keratinocytes and play an indispensable role in tissue homeostasis and repair through secretion of distinct growth factors. γδ T cell based immunotherapy strategies possess great prominence in the treatment because of the property of their MHC-independent cytotoxicity, copious amount of cytokine release, and a immediate response in infections. Understanding the role of γδ T cells in pathogenic infections, wound healing, autoimmune diseases, and cancer might provide knowledge for the successful treatment of these diseases using γδ T cell based immunotherapy. Enhancing the human Vγ9Vδ2 T cells functions by administration of aminobisphosphonates like zoledronate, pamidronate, and bromohydrin pyrophosphate along with cytokines and monoclonal antibodies shows a hopeful approach for treatment of tumors and infections. The current review summarizes the role of γδ T cells in various human diseases and immunotherapeutic approaches using γδ T cells.

Single-nucleotide Polymorphism and Haplotypes of TNIP1 Associated with Systemic Lupus Erythematosus in a Chinese Han Population

Objective.

To determine the association of systemic lupus erythematosus (SLE) with single-nucleotide polymorphisms (SNP) in the TNIP1 gene and compare the expression of this gene in cases and controls from a Chinese Han population in this replication study.

Methods.

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry was used to genotype 19 SNP in TNIP1 in Chinese Han patients with SLE (n = 341) and controls (n = 356). Genotypes were analyzed by codominant, dominant, and recessive models. Analysis of allele frequencies and linkage disequilibrium was also performed. Western blotting and qRT-PCR were used to measure the expression of these genes in peripheral blood mononuclear cells of SLE cases and controls.

Results.

Seven SNP loci were significantly associated with SLE in our population (p < 0.05 for all comparisons). Two TNIP1 gene haplotypes (ATTGCGC and GTCCTAT) were associated with SLE (p = 0.0246 and p = 0.0024, respectively). Western blotting and qRT-PCR results provide evidence that patients with SLE had significantly reduced expression of TNIP1/ABIN-1 relative to controls.

Conclusion.

Analysis of SNP in the TNIP1 gene and expression of this gene in peripheral blood lymphocytes indicated these SNP were associated with the occurrence of SLE in Han Chinese patients. Future studies should examine the roles of these SNP in the pathogenesis of SLE.