Roles of A20 in autoimmune diseases. Immunol Res. 2016;64:337-344. [PMID: 26135958 DOI: 10.1007/s12026-015-8677-6]

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.

Identification of drug targets for Sjögren's syndrome: multi-omics Mendelian randomization and colocalization analyses

Background

Targeted therapy for Sjögren's syndrome (SS) has become an important focus for clinicians. Multi-omics-wide Mendelian randomization (MR) analyses have provided new ideas for identifying potential drug targets.

Methods

We conducted summary-data-based Mendelian randomization (SMR) analysis to evaluate therapeutic targets associated with SS by integrating DNA methylation, gene expression and protein quantitative trait loci (mQTL, eQTL, and pQTL, respectively). Genetic associations with SS were derived from the FinnGen study (discovery) and the GWAS catalog (replication). Colocalization analyses were employed to determine whether two potentially relevant phenotypes share the same genetic factors in a given region. Moreover, to delve deeper into potential regulation among DNA methylation, gene expression, and protein abundance, we conducted MR analysis to explore the causal relationship between candidate gene methylation and expression, as well as between gene expression and protein abundance. Drug prediction and molecular docking were further employed to validate the pharmacological activity of the candidate drug targets.

Results

Upon integrating the multi-omics data, we identified three genes associated with SS risk: TNFAIP3, BTN3A1, and PLAU. The methylation of cg22068371 in BTN3A1 was positively associated with protein levels, consistent with the negative effect of cg22068371 methylation on the risk of SS. Additionally, positive correlations were observed between the gene methylation of PLAU (cg04939496) and expression, as well as between expression and protein levels. This consistency elucidates the promotional effects of PLAU on SS risk at the DNA methylation, gene expression, and protein levels. At the protein level, genetically predicted TNFAIP3 (OR 2.47, 95% CI 1.56-3.92) was positively associated with SS risk, while BTN3A1 (OR 2.96E-03, 95% CI 2.63E-04-3.33E-02) was negatively associated with SS risk. Molecular docking showed stable binding for candidate drugs and target proteins.

Conclusion

Our study reveals promising therapeutic targets for the treatment of SS, providing valuable insights into targeted therapy for SS. However, further validation through future experiments is warranted.

Vasculitis and vasculopathy associated with inborn errors of immunity: an overview

Systemic autoinflammatory diseases (SAIDs) are disorders of innate immunity, which are characterized by unprovoked recurrent flares of systemic inflammation often characterized by fever associated with clinical manifestations mainly involving the musculoskeletal, mucocutaneous, gastrointestinal, and nervous systems. Several conditions also present with varied, sometimes prominent, involvement of the vascular system, with features of vasculitis characterized by variable target vessel involvement and organ damage. Here, we report a systematic review of vasculitis and vasculopathy associated with inborn errors of immunity.

The functional TNFAIP3 rs2230926T/G (Phe127Cys) variant confers risk to systemic lupus erythematosus in a Latin American population

TNFAIP3 is a classical systemic lupus erythematosus (SLE)-associated risk locus identified by genome-wide association studies (GWASs) and replicated by candidate gene association studies primarily in Caucasians and Asians. However, in Latin American populations, its role on SLE susceptibility is not known. We conducted a case-control study to evaluate whether the TNFAIP3 rs2230926T/G (Phe127Cys) variant is associated with risk of developing SLE in a cohort of Mexican patients. The TNFAIP3 rs2230926T/G variant was analyzed in 561 patients with SLE and 499 control subjects, using TaqMan probes. We found that the G allele was associated with susceptibility to SLE under the allelic (OR 2.09, p = 0.005) and genotypic (OR 2.14, p = 0.004) models. In conclusion, our results show that TNFAIP3 rs2230926T/G is a risk factor for the development of SLE in the Mexican population.

Mast cell tolerance in the skin microenvironment to commensal bacteria is controlled by fibroblasts

Activation and degranulation of mast cells (MCs) is an essential aspect of innate and adaptive immunity. Skin MCs, the most exposed to the external environment, are at risk of quickly degranulating with potentially severe consequences. Here, we define how MCs assume a tolerant phenotype via crosstalk with dermal fibroblasts (dFBs) and how this phenotype reduces unnecessary inflammation when in contact with beneficial commensal bacteria. We explore the interaction of human MCs (HMCs) and dFBs in the human skin microenvironment and test how this interaction controls MC inflammatory response by inhibiting the nuclear factor κB (NF-κB) pathway. We show that the extracellular matrix hyaluronic acid, as the activator of the regulatory zinc finger (de)ubiquitinating enzyme A20/tumor necrosis factor α-induced protein 3 (TNFAIP3), is responsible for the reduced HMC response to commensal bacteria. The role of hyaluronic acid as an anti-inflammatory ligand on MCs opens new avenues for the potential treatment of inflammatory and allergic disorders.

The IRG1-Itaconate axis: A regulatory hub for immunity and metabolism in macrophages

Metabolism could be served as a guiding force for immunity, and macrophages undergo drastic metabolic reprogramming during inflammatory processes, including enhancing glycolysis and reshaping the tricarboxylic acid cycle (TCA) cycle. The disrupted TCA cycle facilitates itaconate accumulation, consistent with the significant up-regulation of immune response gene 1 (IRG1) in activated macrophages. IRG1 catalyzes the decarboxylation of cis-aconitate to synthesize itaconate, and notably, the IRG1-Itaconate axis has excellent potential to link macrophages' immunity and metabolism. Here, we review vital molecules that affect the activation of the IRG1-Itaconate axis, including interferon regulatory factor 1/9 (IRF1/9), transcription 1 and 3 (STAT1/3), CCAAT enhancer-binding protein β (C/EBPβ), and the protein kinase C (PKC). We then focus on how the IRG1-Itaconate axis regulates the inflammatory pathway in macrophages, proposed to involve kelch-like ECH-associated protein 1 (Keap1), NOD-, LRR- and pyrin domain-containing 3 (NLRP3), gasdermin D (GSDMD), activating transcription factor 3 (ATF3), receptor-interacting protein kinase-3 (RIPK3), et al. In addition, we provide an overview of the way the axis participates in the metabolism of macrophages. Eventually, we summarize current connections between the IRG1-Itaconate axis and inflammatory diseases, bringing light to new therapeutic opportunities in inflammatory diseases.

TNFAIP3 alleviates pain in lumbar disc herniation rats by inhibiting the NF-κB pathway

Background

It’s been reported that the tumor necrosis factor alpha inducible protein 3 (TNFAIP3) gene played an important role in the pathogenesis of autoimmune and chronic inflammation diseases. Moreover, in degenerative diseases of the lumbar spine the nuclear factor-κB (NF-κB) pathway is significantly activated. This study aimed to explore the role of the tumor necrosis protein-induced zinc finger protein A20 (A20) protein in degenerative diseases of the lumbar spine on the NF-κBp65 pathway.

Methods

A total of 96 rats were randomly divided into 4 groups. Lumbar disc herniation (DH) was set as a sham operation group (Sham group), DH + A20 group and DH + control group (Control group); measured changes in rat paw withdrawal threshold (PWT) and paw withdrawal latency (PWL); detected the proportion of apoptotic cells in a single nucleus pulposus cell suspension, analyzed the correlation between tumor necrosis factor-α (TNF-α) content and pain in DH rats, and the expression changes of NF-κB pathway in nucleus pulposus tissue.

Results

compared with the DH + Control group, the PWT and PWL of the DH + A20 group increased significantly (P<0.05); apoptosis in the DH + A20 group was significantly reduced (P<0.01); the nucleus pulposus tissue and serum levels of TNF-α and interleukin-6 (IL-6) in the DH + A20 rat group were significantly lower than those in the DH + Control group (P<0.05); the protein expression of rats in the DH + A20 group (p-p65) was significantly lower than that in the DH + Control group (P<0.05).

Conclusions

The pain of lumbar disc herniation rats is related to TNF-α, and overexpression of A20 protein can reduce the pain of lumbar disc herniation by inhibiting the NF-κB pathway.

Keywords

Lumbar disc herniation (lumbar DH); tumor necrosis factor-α (TNF-α); interleukin-6 (IL-6); tumor necrosis factor alpha inducible protein 3 (TNFAIP3)

Genome Editing Using CRISPR-Cas9 and Autoimmune Diseases: A Comprehensive Review

Autoimmune diseases are disorders that destruct or disrupt the body's own tissues by its own immune system. Several studies have revealed that polymorphisms of multiple genes are involved in autoimmune diseases. Meanwhile, gene therapy has become a promising approach in autoimmune diseases, and clustered regularly interspaced palindromic repeats and CRISPR-associated protein 9 (CRISPR-Cas9) has become one of the most prominent methods. It has been shown that CRISPR-Cas9 can be applied to knock out proprotein convertase subtilisin/kexin type 9 (PCSK9) or block PCSK9, resulting in lowering low-density lipoprotein cholesterol. In other studies, it can be used to treat rare diseases such as ornithine transcarbamylase (OTC) deficiency and hereditary tyrosinemia. However, few studies on the treatment of autoimmune disease using CRISPR-Cas9 have been reported so far. In this review, we highlight the current and potential use of CRISPR-Cas9 in the management of autoimmune diseases. We summarize the potential target genes for immunomodulation using CRISPR-Cas9 in autoimmune diseases including rheumatoid arthritis (RA), inflammatory bowel diseases (IBD), systemic lupus erythematosus (SLE), multiple sclerosis (MS), type 1 diabetes mellitus (DM), psoriasis, and type 1 coeliac disease. This article will give a new perspective on understanding the use of CRISPR-Cas9 in autoimmune diseases not only through animal models but also in human models. Emerging approaches to investigate the potential target genes for CRISPR-Cas9 treatment may be promising for the tailored immunomodulation of some autoimmune diseases in the near future.

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.

Characterization of Cellular Heterogeneity and an Immune Subpopulation of Human Megakaryocytes

Megakaryocytes (MKs) and their progeny platelets function in a variety of biological processes including coagulation, hemostasis, inflammation, angiogenesis, and innate immunity. However, the divergent developmental and cellular landscape of adult MKs remains mysterious. Here, by deriving the single-cell transcriptomic profiling of MKs from human adult bone marrow (BM), cellular heterogeneity within MKs is unveiled and an MK subpopulation with high enrichment of immune-associated genes is identified. By performing the dynamic single-cell transcriptomic landscape of human megakaryopoiesis in vitro, it is found that the immune signatures of MKs can be traced back to the progenitor stage. Furthermore, two surface markers, CD148 and CD48, are identified for mature MKs with immune characteristics. At the functional level, these CD148+ CD48+ MKs can respond rapidly to immune stimuli both in vitro and in vivo, exhibit high-level expression of immune receptors and mediators, and may function as immune-surveillance cells. The findings uncover the cellular heterogeneity and a novel immune subset of human adult MKs and should greatly facilitate the understanding of the divergent functions of MKs under physiological and pathological conditions.

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.

Haploinsufficiency of A20 Due to Novel Mutations in TNFAIP3

Haploinsufficiency of A20 (HA20) is a newly described immune dysregulation disease due to the loss-of-function mutation in TNFAIP3. In the present study, we report six patients from four unrelated Chinese families with distinct pathogenic mutations in TNFAIP3, including three novel variants. All of the patients presented with early-onset autoimmune/auto-inflammatory diseases, including Crohn's disease, Behcet's disease, systemic lupus erythematosus, and unclassified auto-inflammatory syndrome. Immunological phenotype tests showed elevated levels of serum pro-inflammatory cytokines, reduced naïve B cells and TFH cells, an inverted CD4:CD8 ratio, and increased susceptibility to restimulation-induced cell death (RICD) and FASL-induced apoptosis in derived T cells. Insufficient expression of A20 was found in these patients. A20 truncated protein was detected in mutant-transfected 293T cells. Upon TNF-α stimulation, the NF-κB pathway was over-activated in both derived T cells of these patients and mutant-transfected Hela cells. In conclusion, clinical manifestations are diverse in patients with HA20, even in those with the same TNFAIP3 mutation. A20 inhibits the NF-κB pathway and plays a crucial role in the regulation of cell death. Haploinsufficiency of A20 leads to defects in both innate and adaptive immunity.

A20 Restores Impaired Intestinal Permeability and Inhibits Th2 Response in Mice with Colitis

BACKGROUND/AIMS

The etiology of inflammatory bowel disease is multifactorial and still obscure. The protective role of ubiquitin E3 ligase A20 (A20) in colitis needs to be further elucidated. This study aimed to investigate whether A20 exogenous administration restored impaired intestinal permeability and inhibited T helper (Th)2 response in mice with colitis.

METHODS

The effect of A20 overexpression in colonic mucosa on epithelial barrier function and T cell differentiation was evaluated in mice with dextran sulfate sodium (DSS)-induced chronic colitis.

RESULTS

A20 rectal treatment alleviated DSS-induced chronic colitis and restored impaired intestinal permeability. Oral challenge with 2% DSS elicited a Th2-type response in mice with colitis, and A20 rectal treatment inhibited CD4⁺ interleukin (IL)-4⁺ T cell differentiation and proliferation. In addition, the RNA expressions of Th2-related costimulatory molecular T-cell immunoglobulin and mucin domain (TIM)-1 and IL-4 were suppressed, while thrombospondin (TSP)-1 and interferon (IFN)-γ expressions were upregulated, after A20 rectal administration.

CONCLUSION

A20 rectal treatment restores impaired intestinal permeability and inhibits activated Th2 cell response in mice with colitis.

Genetic contributors and soluble mediators in prediction of autoimmune comorbidity

Comorbidities including subclinical atherosclerosis, neuropsychological aberrations and lymphoproliferation represent a major burden among patients with systemic autoimmune diseases; they occur either as a result of intrinsic disease related characteristics including therapeutic interventions or traditional risk factors similar to those observed in general population. Soluble molecules recently shown to contribute to subclinical atherosclerosis in the context of systemic lupus erythematosus (SLE) include among others B-cell activating factor (BAFF), hyperhomocysteinemia, parathormone (PTH) levels and autoantibodies against oxidized lipids. Variations of the 5, 10- methylenetetrahydrofolate reductase (MTHFR) gene -the main genetic determinant of hyperhomocystenemia in humans-as well the interferon regulatory factor-8 (IRF8), FcγRIIA and BAFF genes have been all linked to subclinical atherosclerosis in SLE. BAFF variants have been also found to confer increased risk for subclinical atherosclerosis and lymphoma development in Sjogren's syndrome (SS) patients. Other genes shown to be implicated in SS lymphoproliferation include genes involved a. in inflammatory responses such as the NFκB regulator Tumor necrosis factor alpha-induced protein 3 (TNFAIP3) and the Leukocyte immunoglobulin-like receptor A3 (LILRA3) immunoreceptor, b. B cell activation and signaling (BAFF/BAFF-receptor), c. type I IFN pathway such as three-prime repair exonuclease 1 (TREX1), d. epigenetic processes including DNA methylation (MTHFR rs1801133, 677T allele) and e. genomic instability (MTHFR rs1801131, 1298C allele). Emerging soluble biomarkers for SS related lymphoma include mediators of B cell growth and germinal center formation such as BAFF, FMS-like tyrosine kinase 3 ligand (Flt-3L) and CXCL13 as well as inflammatory contributors such as inteleukin (IL)-17, IL-18, ASC, LILRA3 and the extracellular lipoprotein-associated phospholipase A2 (Lp-PLA2). In regard to fatigue and neuropsychologic features in the setting of SS, contributing factors such as BAFF variants, antibodies against neuropeptides, proteins involved in nervous system function as well as inflammatory cytokines have been reported.

Decreased A20 expression on circulating CD56bright NK cells contributes to a worse disease status in patients with ankylosing spondylitis

A20, a pivotal anti-inflammatory protein, preserves immune homeostasis and regulates prolonged inflammation. A previous study has shown that A20 expression levels are down-regulated in peripheral blood mononuclear cells (PBMCs) from patients with ankylosing spondylitis (AS). However, the precise role of A20 in reducing autoimmune disorders needs to be further elucidated. In this study, A20 expression was found to be preferentially reduced on circulating CD56^bright natural killer (NK) cells in patients with AS, and its level was negatively correlated with that of proinflammatory cytokines. Further investigation demonstrated that A20 reduces interferon (IFN)-γ and tumour necrosis factor (TNF)-α production in CD56^bright NK cells after stimulation with monokines or phorbol myristate acetate (PMA)/ionomycin(P/I). Furthermore, CD56^bright NK cells isolated from AS patients promote TNF-α secretion by autologous monocytes, and increasing the A20 expression level partially attenuates this process. More importantly, decreased A20 expression on circulating CD56^bright NK cells is associated with worse disease status in patients with AS. Our findings reveal that A20 participates in the pathogenesis of AS by negatively regulating CD56^bright NK cells and that its reduced expression contributes to a worsened disease status in patients with AS.

Herbs-partitioned moxibustion alleviates aberrant intestinal epithelial cell apoptosis by upregulating A20 expression in a mouse model of Crohn’s disease

BACKGROUND

A20 inhibits intestinal epithelial cell apoptosis in Crohn’s disease, and herbs-partitioned moxibustion (HPM) has been demonstrated to be an effective treatment for Crohn’s disease. However, the mechanism by which HPM reduces intestinal epithelial cell apoptosis in Crohn’s disease has not been thoroughly elucidated to date.

AIM

To elucidate whether HPM exerts its effects by upregulating A20 to affect intestinal epithelial cell apoptosis in a Crohn’s disease mouse model.

METHODS

In this study, mice with A20 deletion in intestinal epithelial cells (A20^IEC-KO) were utilized to establish a Crohn’s disease mouse model with 2,4,6-trinitrobenzene sulfonic acid (TNBS) administration, as well as wild-type mice. Mice were randomly divided into normal control (NC), model control (MC), mesalazine (MESA), and HPM groups. The morphology of the colonic mucosa was observed by hematoxylin-eosin staining, and serum endotoxin and apoptosis of epithelial cells were evaluated by enzyme-linked immunosorbent assay and terminal dUTP nick-end labeling assay accordingly. The protein expression levels of A20 and tumor necrosis factor receptor 1 (TNFR1)-related signaling molecules were evaluated by Western blot, and co-expression of A20 and TNFR1-associated death domain (TRADD) and co-expression of A20 and receptor-interacting protein 1 (RIP1) were observed by double immunofluorescence staining.

RESULTS

The intestinal epithelial barrier was noted to have an improvement in the HPM group of wild-type (WT) mice compared with that in A20^IEC-KO mice. Compared with A20 ^IEC-KO HPM mice, serum endotoxin levels and apoptosis percentages were decreased (P < 0.01), A20 expression levels were increased (P < 0.01), and expression of TNFR1, TRADDD, and RIP1 was decreased in the HPM group of WT mice (P_TNFR1 < 0.05, P_TRADD < 0.01, P_RIP1 < 0.01). Both of the co-expression of A20/TRADD and A20/RIP1 showed a predominantly yellow fluorescence in the HPM group of WT mice, while a predominantly red fluorescence was noted in the HPM group of A20^IEC-KO mice.

CONCLUSION

Our findings suggest that HPM in treating Crohn’s disease functions possibly via upregulation of the A20 expression level, resulting in downregulation of TNFR1, TRADD, and RIP1 to alleviate increased cell apoptosis in the intestinal epithelial barrier in Crohn's disease.

NFκB and Kidney Injury

The global burden of chronic kidney disease will increase during the next century. As NFκB, first described more than 30 years ago, plays a major role in immune and non-immune-mediated diseases and in inflammatory and metabolic disorders, this review article summarizes current knowledge on the role of NFκB in in vivo kidney injury and describes the new and so far not completely understood crosstalk between canonical and non-canonical NFκB pathways in T-lymphocyte activation in renal disease.

miR-873a-5p Targets A20 to Facilitate Morphine Tolerance in Mice

Long-term morphine administration leads to tolerance and a gradual reduction in analgesic potency. Noncoding microRNAs (miRNAs) modulate gene expression in a posttranscriptional manner, and their dysregulation causes various diseases. Emerging evidence suggests that miRNAs play a regulatory role in the development of morphine tolerance. In the present study, we hypothesized that miR-873a-5p is a key functional small RNA that participates in the development and maintenance of morphine tolerance through the regulation of A20 (tumor necrosis factor α-induced protein 3, TNFAIP3) in mice. We measured the percentage of maximum possible effect (MPE %) to evaluate the analgesic effect of morphine. The expression of miR-873a-5p and its target gene A20 were determined after the morphine-tolerant model was successfully established. Intrathecal injection with lentivirus to intervene in the expression of A20 and the miR-873a-5p antagomir was used to explore the role of miR-873a-5p in the development of morphine tolerance. Chronic morphine administration significantly increased the expression of miR-873a-5p, which was inversely correlated with decreased A20 expression in the spinal cord of morphine-tolerant mice. Downregulation of miR-873a-5p in the spinal cord attenuated and partly reversed the development of morphine tolerance accompanied by overexpression of A20. Similarly, A20 was upregulated by a recombinant lentivirus vector, which attenuated and reversed the pathology of morphine tolerance by inhibiting the activation of nuclear factor (NF)-κB. Collectively, our results indicated that miR-873a-5p targets A20 in the spinal cord to facilitate the development of morphine tolerance in mice. Downregulating the expression of miR-873a-5p may be a potential strategy to ameliorate morphine tolerance.

A20 Orchestrates Inflammatory Response in the Oral Mucosa through Restraining NF-κB Activity

Deregulated immune response to a dysbiotic resident microflora within the oral cavity leads to chronic periodontal disease, local tissue destruction, and various systemic complications. To preserve tissue homeostasis, inflammatory signaling pathways involved in the progression of periodontitis must be tightly regulated. A20 (TNFAIP3), a ubiquitin-editing enzyme, has emerged as one of the key regulators of inflammation. Yet, the function of A20 in the oral mucosa and the biological pathways in which A20 mitigates periodontal inflammation remain elusive. Using a combination of in vivo and ex vivo disease models, we report in this study that A20 regulates inflammatory responses to a keystone oral bacterium, Porphyromonas gingivalis, and restrains periodontal inflammation through its effect on NF-κB signaling and cytokine production. Depletion of A20 using gene editing in human macrophage-like cells (THP-1) significantly increased cytokine secretion, whereas A20 overexpression using lentivirus infection dampened the cytokine production following bacterial challenge through modulating NF-κB activity. Similar to human cells, bone marrow-derived macrophages from A20-deficient mice infected with P. gingivalis displayed increased NF-κB activity and cytokine production compared with the cells isolated from A20-competent mice. Subsequent experiments using a murine ligature-induced periodontitis model showed that even a partial loss of A20 promotes an increased inflammatory phenotype and more severe bone loss, further verifying the critical function of A20 in the oral mucosa. Collectively, to our knowledge, these findings reveal the first systematic evidence of a physiological role for A20 in the maintenance of oral tissue homeostasis as a negative regulator of inflammation.

TNFAIP3 F127C Coding Variation in Greek Primary Sjogren's Syndrome Patients

Tumor necrosis factor, alpha-induced protein 3 (TNFAIP3) gene encodes the A20 protein, an important negative feedback regulator of the nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) pathway. A coding TNFAIP3 variant, namely rs2230926, has been previously linked to B cell non-Hodgkin's lymphoma (NHL) development in patients with Sjogren's syndrome (SS) of French and UK origin. Herein, we aimed to determine the prevalence of rs2230926 in a Greek primary SS cohort and explore possible associations with disease characteristics. The rs2230926 gene variant was genotyped in 327 primary Greek SS patients (ninety-one complicated by NHL (SS-lymphoma)) and 448 Greek healthy controls (HC) of similar age and sex distribution. Clinical and laboratory characteristics were also recorded and gene expression of relevant genes of the NF-κB pathway was quantitated by real-time PCR in available whole peripheral blood (PB) from 165 primary SS patients. Increased prevalence of the rs2230926 mutant variant was detected in both SS-lymphoma and SS-nonlymphoma subgroups compared to HC (8.8% vs. 7.6% vs. 3.6%, p values: 0.04 and 0.03, respectively) in association with higher IgM, LDH serum levels, and PB Bcl-XL transcripts but lower leucocyte and neutrophil counts. Of interest, approximately one-fifth of SS-lymphoma cases with age at disease onset ≤ 40 years carried the rs2230926 variant (18.2% vs. 3.6%, OR 95% (CI): 6.0 (1.8–19.8), p value: 0.01). We postulate that deregulation of the NF-κB pathway as a result of the TNFAIP3 rs2230926 aberration increases SS and SS lymphoma susceptibility particularly in patients with early disease onset.

Functional variants of TNFAIP3 are associated with systemic lupus erythematosus in a cohort of Chinese Han population

Tumor necrosis factor-alpha-induced protein 3 (TNFAIP3) is a negative regulator of NF-κB activity. We previously reported that the paired tandem polymorphic dinucleotides TT > A (rs148314165, rs200820567 of TNFAIP3) conferred the risk for systemic lupus erythematosus (SLE) in European and Korean populations. We investigated the genetic association of the TT > A variants, as well as the functional coding variant rs2230926 in exon 3 of TNFAIP3 in 1229 Chinese Han SLE patients and 1608 matched population controls. We further evaluated the role of these variants in regulating expression of the TNFAIP3 gene and NF-κB signaling pathway in their peripheral blood mononuclear cells from Chinese SLE patients. The TT > A variants and the TNFAIP3 exon 3 coding variant rs2230926 demonstrated significant associations in SLE (P_TT > A = 8.96 × 10^-12, odds ratio [OR] = 2.07, 95% confidence interval [CI] = 1.68-2.55). SLE patients carrying the risk A allele showed reduced messenger RNA expression of the TNFAIP3 gene and increased expression of NF-κB1 in PBMCs. Conditional analyses revealed that the TT > A variants are likely to be causal variants in Chinese Han SLE patients. The TT > A variants associated with Chinese Han SLE and negatively regulate the expression of the TNFAIP3 gene resulting in enhanced NF-κB activity.

Infantile Onset Intractable Inflammatory Bowel Disease Due to Novel Heterozygous Mutations in TNFAIP3 (A20)

BACKGROUND

Mutations in tumor necrosis factor alpha-induced protein 3 (TNFAIP3), a key player in the negative feedback regulation of nuclear factor-κB signaling, have recently been recognized as leading to early onset autoinflammatory and autoimmune syndrome. Here, we have reported the phenotypes of 3 infantile onset intractable inflammatory bowel disease (IBD) patients with TNFAIP3 mutations and reviewed previously reported cases to establish phenotypic features associated with TNFAIP3 monogenicity.

METHODS

From January 1, 2015, to December 31, 2017, we recruited 58 infantile-onset IBD patients. Targeted sequencing and whole-exome sequencing were performed. Sanger sequencing confirmed the variants and determined the parental origin. We followed all the patients with TNFAIP3 mutations in our cohort and analyzed their clinical data.

RESULTS

Genetic screening in all 58 patients with infantile-onset IBD revealed 44 (75.9%) cases of monogenic disorders, and 3 de novo TNFAIP3 mutations were identified, including 1 nonsense and 2 frame shift mutations. All the mutations resulted in premature stop codon. All 3 patients had multiple systemic involvements, with predominant gastrointestinal diseases.

CONCLUSIONS

Most infantile-onset IBD was associated with monogenetic mutation, and in addition to the 50 reported genes, other rare genetic variants need to be determined. TNFAIP3 may be an important candidate gene. The treatment of TNFAIP3-associated infantile-onset-IBD was challenging. 10.1093/ibd/izy165_video1izy165.video15789607089001.

Genetic variants upstream of TNFAIP3 in the 6q23 region are associated with liver disease severity in HIV/HCV-coinfected patients: A cross-sectional study

BACKGROUND

TNFAIP3 is a crucial hepatoprotective factor due to its anti-inflammatory, anti-apoptotic, anti-oxidant and pro-regenerative functions. The aim of this study was to analyze the associations between genetic variants upstream of TNFAIP3 (rs675520, rs9376293 and rs6920220) and liver fibrosis severity and inflammation in HIV/HCV-coinfected patients.

METHODS

A cross-sectional study was carried out in 215 HIV/HCV-coinfected patients, who underwent a liver biopsy. TNFAIP3 polymorphisms were genotyped using GoldenGate® assay. Outcome variables were: a) liver fibrosis (Metavir score) [fibrosis stage (F0, F1, F2, F3 and F4) and advanced fibrosis and cirrhosis (F ≥ 3 and F4, respectively)]; b) non-invasive indexes [FIB-4, APRI, and their cut-offs (FIB-4 ≥ 3.25 and APRI≥1.5)]; c) inflammation-related biomarkers (leptin, HGF, NGF, sFasL, sFas, MIF, HA, Ang-2, TIMP1, MMP1 and MMP2).

RESULTS

Patients with rs675520 AG/GG genotypes had decreased odds of having cirrhosis (F4) and advanced fibrosis (FIB-4 ≥ 3.25 and APRI≥1.5) [adjusted Odd Ratio (aOR) = 0.30 (p = 0.025), aOR = 0.20 (p = 0.014), and aOR = 0.34 (p = 0.017), respectively] and lower levels of FIB-4 and APRI [adjusted arithmetic mean ratio (aAMR) = 0.76 (p = 0.003) and aAMR = 0.72 (p = 0.006), respectively]. Patients with rs9376293 CT/CC genotypes had decreased odds of APRI≥1.5 [aOR = 0.39 (p = 0.030)] and lower levels of APRI [aAMR = 0.77 (p = 0.018)]. Patients with rs6920220 AG/AA genotypes had higher odds of having FIB-4 ≥ 3.25 [aOR = 3.72 (p = 0.043)]. Moreover, rs675520 AG/GG genotypes, compared to AA genotype, were associated with lower levels of leptin and NGF (p = 0.002 and p = 0.001, respectively) and higher levels of sFas, MIF, TIMP1 and MMP2 (p = 0.004, p = 0.007, p = 0.020 and p = 0.036, respectively). Also, rs9376293 CT/CC genotypes were related to lower leptin levels (p = 0.026) and higher sFas, MIF, TIMP1 and MMP2 levels (p = 0.029, p = 0.040, p = 0.022 and p = 0.024, respectively).

CONCLUSIONS

Genetic variants upstream of TNFAIP3 were associated with the liver fibrosis severity and inflammation in HIV/HCV-coinfected patients.

The proinflammatory effects of macrophage-derived NADPH oxidase function in autoimmune diabetes

Type 1 diabetes (T1D) is an autoimmune disease culminating in the destruction of insulin-producing pancreatic β-cells. While ultimately a T cell-mediated disease, macrophages play an indispensable role in disease initiation and progression. Infiltrating macrophages generate an inflammatory environment by releasing NADPH oxidase-derived superoxide and proinflammatory cytokines. The synthesis of reactive oxygen species (ROS) is acknowledged as putative factors contributing to autoimmunity and β-cell damage in T1D. In addition to direct lysis, free radicals collectively participate in β-cell destruction by providing a redox-dependent third signal necessary for islet-reactive CD4 and CD8 T cell maturation and by inducing oxidative post-translational modifications of β-cell epitopes to further exacerbate autoimmune responses. This review will provide an overview of macrophage function and a synergistic cross-talk with redox biology that contributes to autoimmune dysregulation in T1D.

Genomics, Biology, and Human Illness: Advances in the Monogenic Autoinflammatory Diseases

The monogenic autoinflammatory diseases are a group of illnesses with prominent rheumatic manifestations that are characterized by genetically determined recurrent sterile inflammation and are thus inborn errors of innate immunity. Molecular targeted therapies against inflammatory cytokines, such as interleukin 1 and tumor necrosis factor, and intracellular cytokine signaling pathways have proved effective in many cases. Emerging next-generation sequencing technologies have accelerated the identification of previously unreported genes causing autoinflammatory diseases. This review covers several of the prominent recent advances in the field of autoinflammatory diseases, including gene discoveries, the elucidation of new pathogenic mechanisms, and the development of effective targeted therapies.

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.

CRISPR/cas9 mediated knockout of an intergenic variant rs6927172 identified IL-20RA as a new risk gene for multiple autoimmune diseases

Genetic variants near the tumor necrosis factor-α-induced protein 3 gene (TNFAIP3) at the chromosomal region 6q23 demonstrated significant associations with multiple autoimmune diseases. The signals of associations have been explained to the TNFAIP3 gene, the most likely causal gene. In this study, we employed CRISPR/cas9 genome-editing tool to generate cell lines with deletions including a candidate causal variant, rs6927172, at 140 kb upstream of the TNFAIP3 gene. Interestingly, we observed alterations of multiple genes including IL-20RA encoding a subunit of the receptor for interleukin 20. Using Electrophoretic mobility shift assay (EMSA), Western blotting, and chromatin conformation capture we characterized the molecular mechanism that the DNA element carrying the variant rs6927172 influences expression of IL-20RA and TNFAIP3 genes. Additionally, we developed a new use of the transcription activator-like effector (TALE) to study the role of the variant in regulating expressions of its target genes. In summary, we generated deletion knockouts that included the candidate causal variant rs6927172 in HEK293T cells provided new evidence and mechanism for IL-20RA gene as a risk factor for multiple autoimmune diseases.

Loss of A20 in BM-MSCs regulates the Th17/Treg balance in Rheumatoid Arthritis

Mesenchymal stem cells (MSCs) are multi-potent cells that are self-renewable and possess the potential to differentiate into multiple lineages. Several studies demonstrated that MSCs could regulate a Th17/Treg balance and could be a potential therapeutic target for Rheumatoid Arthritis (RA). A20 is highly expressed in many cell types after the stimulation of TNF-α, where it may inhibit pro-inflammatory cytokine secretion. However, the expression of A20 in BM-MSCs in RA is not fully understood. In our study, we found that A20 was decreased in RA patients’ bone marrow MSCs (BM-MSCs), and with more IL-6 secretion, the balance of Th17/Treg was broken. In CIA mice, we found a moderate A20 decrease in mice MSCs as compared with those of control group in mRNA and protein levels. However, the IL-6 expression was increased. After umbilical cord MSCs treatment, A20 and IL-6 expressions were equal to the control group. Thus, our study indicates that loss of A20 in MSCs regulates the Th17/Treg balance in RA and the regulatory role of A20 in pro-inflammatory IL-6 production could be a potential target for the transfer of MSCs in RA adoptive therapy.

A20 inhibits lipopolysaccharide-induced inflammation in enterocytes

AIM

To examine the role of A20 in the regulation of intestinal epithelial cells (IECs) inflammation.

METHODS

Using gene transfection, both stable overexpression and knockdown A20-expressed HT-29 cell lines were established. Accordingly, the cells were divided into the following groups: The control group, the A20 overexpression group, the A20 knockdown group and the respective controls. A20 was stimulated with lipopolysaccharide (LPS) in a dose- and time-dependent manner and was detected using western blotting and real-time polymerase chain reaction (PCR) analyses. Immunofluorescence and western blotting analyses were performed to investigate the role of A20 in the regulation of nuclear factor (NF)-κB activation and translocation into the nucleus. ELISA and real-time PCR were performed to examine A20 in regulating the release of the following inflammatory cytokines: Tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-8.

RESULTS

The expression of A20 in IECs was inducible. When intestinal epithelial cells were subjected to the stimulation of LPS, the expression of A20 was increased, and the expression of A20 was induced in a dose- and time-dependent manner. The expression of A20 was very low in HT-29 cells without LPS stimulation but rapidly increased and was maintained at a high level 2-4 h after stimulation with LPS. These levels gradually declined with a change in time-course, and the expression of A20 increased with increasing LPS stimulation. Western blotting and immunofluorescence revealed that overexpression of A20 can inhibit NF-κB activation and its translocation to the nucleus. The overexpression of A20 can reduce the levels of proinflammatory cytokines involved in the pathophysiology of inflammatory bowel disease. There was no significant difference in the expression of IL-8 mRNA in the control group, A20 overexpression group or A20 knockdown group without LPS stimulation (P > 0.05); however, while after 2 h, 4 h and 8 h stimulation with LPS, the expression of IL-8 in the A20 overexpression group was lower than the control group and the A20 knockdown group (P < 0.05 or P < 0.01). The expression of TNF-α was different at different time points after 8 h of LPS stimulation (F = 31.33, DF = 5, P < 0.001), and the expression of TNF-α increased as the LPS stimulation time increased. Upon LPS stimulation, lower levels of TNF-α were detected in the A20 overexpression cell lines (P < 0.05). There were no significant differences in the induction of IL-6 and IL-1β among the control group, A20 overexpression group and A20 knockdown group (P > 0.05).

CONCLUSION

A20 plays an important role in limiting inflammation by inhibiting LPS-induced NF-κB responses in the gut luminal. A20 may be a potential therapeutic tool for inflammatory diseases.