Enhancement of Th1/Th17 inflammation by TRIM21 in Behçet's disease

A Interacting Model: How TRIM21 Orchestrates with Proteins in Intracellular Immunity

Tripartite motif-containing protein 21 (TRIM21), identified as both a cytosolic E3 ubiquitin ligase and FcR (Fragment crystallizable receptor), primarily interacts with proteins via its PRY/SPRY domains and promotes their proteasomal degradation to regulate intracellular immunity. But how TRIM21 involves in intracellular immunity still lacks systematical understanding. Herein, it is probed into the TRIM21-related literature and raises an interacting model about how TRIM21 orchestrates proteins in cytosol. In this novel model, TRIM21 generally interacts with miscellaneous protein in intracellular immunity in two ways: For one, TRIM21 solely plays as an E3, ubiquitylating a glut of proteins that contain specific interferon-regulatory factor, nuclear transcription factor kappaB, virus sensors and others, and involving inflammatory responses. For another, TRIM21 serves as both E3 and specific FcR that detects antibody-complexes and facilitates antibody destroying target proteins. Correspondingly delineated as Fc-independent signaling and Fc-dependent signaling in this review, how TRIM21's interactions contribute to intracellular immunity, expecting to provide a systematical understanding of this important protein and invest enlightenment for further research on the pathogenesis of related diseases and its prospective application is elaborated.

TRIM21 of Micropterus salmoides exerts antiviral roles against largemouth bass ulcer syndrome virus

Tripartite motif 21 (TRIM21), a member of the TRIM family, plays an important role in apoptosis, autophagy and ubiquitination in human, and has been proven to play antiviral roles in different organisms. In this study, the TRIM21 gene of Micropterus salmoides (MsTRIM21) was cloned, and it encoded 376 amino acids, which showed 89.3% similarity with Micropterus dolomieu and 38.3% with homo sapiens. Bioinformatics analysis revealed MsTRIM21 contained four domains: C4HC3-type RING-variant (RINGv), coiled coil, PRY and SPRY. The high expression level of MsTRIM21 could be detected in liver, stomach and muscle of healthy Micropterus salmoides, and it was significantly upregulated in head kidney, muscle, gill and brain and significantly down-regulated in the stomach of Micropterus salmoides infected with largemouth bass ulcer syndrome virus (LBUSV). The overexpression of MsTRIM21 could significantly inhibit the viral replication in vitro, evidenced by the reduction of CPE severity and the downregulation of the viral gene transcription. In addition, the overexpression of MsTRIM21 could significantly increase the expression level of interferon regulatory factor (IRF) 3, IRF7, myxovirus resistance 1 (Mx1), interferon stimulated gene 15 (ISG15), double-stranded RNA-activated protein kinase (PKR) and tumor necrosis factor α (TNF-α) in vitro, indicating the enhancement of innate immune response and inflammatory response, which may directly affect the replication of LBUSV. Thus, these results provide new lights on the roles of fish TRIM21 in innate immune response against iridovirus.

Comprehensive profiling of extracellular vesicles in uveitis and scleritis enables biomarker discovery and mechanism exploration

BACKGROUND

Uveitis and posterior scleritis are sight-threatening diseases with undefined pathogenesis and accurate diagnosis remains challenging.

METHODS

Two plasma-derived extracellular vesicle (EV) subpopulations, small and large EVs, obtained from patients with ankylosing spondylitis-related uveitis, Behcet's disease uveitis, Vogt-Koyanagi-Harada syndrome, and posterior scleritis were subjected to proteomics analysis alongside plasma using SWATH-MS. A comprehensive bioinformatics analysis was performed on the proteomic profiles of sEVs, lEVs, and plasma. Candidate biomarkers were validated in a new cohort using ELISA. Pearson correlation analysis was performed to analyze the relationship between clinical parameters and proteomic data. Connectivity map database was used to predict therapeutic agents.

RESULTS

In total, 3,668 proteins were identified and over 3000 proteins were quantified from 278 samples. When comparing diseased group to healthy control, the proteomic profiles of the two EV subgroups were more correlated with disease than plasma. Comprehensive bioinformatics analysis highlighted potential pathogenic mechanisms for these diseases. Potential biomarker panels for four diseases were identified and validated. We found a negative correlation between plasma endothelin-converting enzyme 1 level and mean retinal thickness. Potential therapeutic drugs were proposed, and their targets were identified.

CONCLUSIONS

This study provides a proteomic landscape of plasma and EVs involved in ankylosing spondylitis-related uveitis, Behcet's disease uveitis, Vogt-Koyanagi-Harada syndrome, and posterior scleritis, offers insights into disease pathogenesis, identifies valuable biomarker candidates, and proposes promising therapeutic agents.

Prognostic and clinicopathological significance of TRIM21 in various cancers: A meta and bioinformatic analysis

BACKGROUND

Tripartite motif-containing protein 21 (TRIM21), a member of the ubiquitin ligase family, makes a significant contribution to the ubiquitination of multiple tumor marker proteins associated with tumor cell proliferation, metastasis and selective apoptosis. As the research further develops, an increasing number of studies have manifested that the TRIM21 expression level can be considered an indicator of cancer prognosis. However, the interrelationship between TRIM21 and multiple forms of carcinogens has not been demonstrated in a meta-analysis.

METHODS

We performed a systematic literature retrieval in various electronic databases including PubMed, Embase, Web of Science, Wanfang and China National Knowledge Infrastructure. Besides, the hazard ratio (HR) and the pooled relative risk (RR) were integrated in the assessment of cancer incidence and cancer mortality by Stata SE15.1. Additionally, we used an online database based on The Cancer Genome Atlas (TCGA) to further validate our results.

RESULTS

A total of 17 studies were included, totaling 7239 participants. High expression of TRIM21 was significantly correlated with better OS (HR = 0.74; 95% CI: 0.57-0.91; P < .001) and progression-free survival (PFS) (HR = 0.66; 95% CI: 0.42-0.91; P < .001). We found that high TRIM21 expression predicted significant impact on clinical characteristics like decreased lymph node metastasis (RR = 1.12; 95% CI: 0.97-1.30; P < .001), tumor stage (RR = 1.06; 95% CI: 0.82-1.37; P < .001) and tumor grade (RR = 1.07; 95% CI: 0.56-2.05; P < .001). However, TRIM21 expression had no significant impact on other clinical characteristics such as age (RR = 1.06; 95% CI: 0.91-1.25; P = .068), sex (RR = 1.04; 95% CI: 0.95-1.12; P = .953), or tumor size (RR = 1.14; 95% CI: 0.97-1.33; P = .05). Based on the Gene Expression Profiling Interactive Analysis (GEPIA) online analysis tool, TRIM21 was significantly downregulated in 5 cancers while significantly upregulated in 2 cancers, and the descending expression of TRIM21 predicted shorter OS in 5 cancers, worse PFS in 2 malignancies, while the elevated expression of TRIM21 predicted shorter OS and worse PFS in 2 carcinomas.

CONCLUSIONS

TRIM21 could serve as a new biomarker for patients with solid malignancies and could be a potential therapeutic target for patients.

Identification of the immune-related biomarkers in Behcet's disease by plasma proteomic analysis

BACKGROUND

This study aimed to investigate the expression profile of immune response-related proteins of Behcet's disease (BD) patients and identify potential biomarkers for this disease.

METHODS

Plasma was collected from BD patients and healthy controls (HC). Immune response-related proteins were measured using the Olink Immune Response Panel. Differentially expressed proteins (DEPs) were used to construct prediction models via five machine learning algorithms: naive Bayes, support vector machine, extreme gradient boosting, random forest, and neural network. The prediction performance of the five models was assessed using the area under the curve (AUC) value, recall (sensitivity), specificity, precision, accuracy, F1 score, and residual distribution. Subtype analysis of BD was performed using the consensus clustering method.

RESULTS

Proteomics results showed 43 DEPs between BD patients and HC (P < 0.05). These DEPs were mainly involved in the Toll-like receptor 9 and NF-κB signaling pathways. Five models were constructed using DEPs [interleukin 10 (IL10), Fc receptor like 3 (FCRL3), Mannan-binding lectin serine peptidase 1 (MASP1), NF2, moesin-ezrin-radixin like (MERLIN) tumor suppressor (NF2), FAM3 metabolism regulating signaling molecule B (FAM3B), and O-6-methylguanine-DNA methyltransferase (MGMT)]. Among these models, the neural network model showed the best performance (AUC = 0.856, recall: 0.692, specificity: 0.857, precision: 0.900, accuracy: 0.750, F1 score: 0.783). BD patients were divided into two subtypes according to the consensus clustering method: one with high disease activity in association with higher expression of tripartite motif-containing 5 (TRIM5), SH2 domain-containing 1A (SH2D1A), phosphoinositide-3-kinase adaptor protein 1 (PIK3AP1), hematopoietic cell-specific Lyn substrate 1 (HCLS1), and DNA fragmentation factor subunit alpha (DFFA) and the other with low disease activity in association with higher expression of C-C motif chemokine ligand 11 (CCL11).

CONCLUSIONS

Our study not only revealed a distinctive immune response-related protein profile for BD but also showed that IL10, FCRL3, MASP1, NF2, FAM3B, and MGMT could serve as potential immune biomarkers for this disease. Additionally, a novel molecular disease classification model was constructed to identify subsets of BD.

TRIM21 ameliorates hepatic glucose and lipid metabolic disorders in type 2 diabetes mellitus by ubiquitination of PEPCK1 and FASN

Hepatic glucose and lipid metabolism disorders promote the development and progression of type 2 diabetes mellitus (T2DM), yet the underlying mechanisms are not fully understood. Here, we identify tripartite motif-containing protein 21 (TRIM21), a class IV TRIM family member, as a pivotal regulator of hepatic metabolism in T2DM for the first time. Bioinformatic analysis suggests that TRIM21 expression is significantly reduced in T2DM patients. Intriguingly, in a mouse model of obese diabetes, TRIM21 expression is predominantly reduced in the liver rather than in other metabolic organs. It is further demonstrated that hepatic overexpression of TRIM21 significantly ameliorates glucose intolerance, insulin resistance, hepatic steatosis, and dyslipidemia in obese diabetic mice. In contrast, the knockdown of TRIM21 promotes glucose intolerance, insulin resistance, and triglyceride accumulation. Mechanistically, both phosphoenolpyruvate carboxykinase 1 (PEPCK1) and fatty acid synthase (FASN) are the hepatic targets of TRIM21. We revealed that TRIM21 promotes the degradation of PEPCK1 and FASN through a direct protein-protein interaction mediated K48-linked ubiquitination. Notably, overexpression of PEPCK1 and FASN essentially abolished the beneficial effects achieved by TRIM21 overexpression in obese diabetic mice. Overall, our data demonstrate that TRIM21 is a novel regulator of hepatic metabolic disorder, and suggest TRIM21 as a promising therapeutic target for T2DM.

Mucocutaneous manifestations of Behçet's disease: Pathogenesis and management from perspectives of vasculitis

Behçet's disease (BD) is a systemic inflammatory disorder characterized by vasculitis affecting blood vessels of any caliber or type. It can present with a wide spectrum of vasculitic lesions, including erythema nodosum-like lesions and retinal vasculitis, and may also lead to larger vessel diseases, such as aortic aneurysm and deep vein thrombosis. The full etiology of BD remains unclear, but it is considered a polygenetic disease with multiple genetic risk factors that promote immune dysregulation and thrombophilia. Inflammation can be triggered by environmental factors, such as bacteria or viruses, and the dysregulation of innate and adaptive immune cell subsets. Neutrophils and lymphocytes are the primary players involved in BD pathogenesis, with specific innate (i.e., neutrophil-derived reactive oxygen species and neutrophil extracellular traps) and adaptive (i.e., anti-endothelial cell antibodies) processes inducing endothelial cell activation and chemotaxis of inflammatory cells, leading to coagulation and vasculitis. These inflammation-induced vasculitic or vasculopathic features are observed in most mucocutaneous BD lesions, although vasculitis per se is often pathologically evident only during a brief period of the disease process. Due to the multifactorial nature of BD-associated inflammation, broad-spectrum anti-inflammatory medications, including glucocorticoids and immunosuppressive drugs, have been the mainstay for managing BD. In addition, inhibitors of interleukin (IL)-1, tumor necrosis factor (TNF)-α, and IL-17, which target innate and adaptive immune functions dysregulated in BD, have emerged as promising new therapeutics. In this review, we discuss the muco-cutaneous manifestations of BD by focusing on the underlying vasculitic components in their pathologies, as well as the current array of treatment options.

NLRC4-mediated activation of CD1c+ DC contributes to perpetuation of synovitis in rheumatoid arthritis

The individual contribution of specific myeloid subsets such as CD1c+ conventional DC (cDC) to perpetuation of rheumatoid arthritis (RA) pathology remains unclear. In addition, the specific innate sensors driving pathogenic activation of CD1c+ cDC in patients with RA and their functional implications have not been characterized. Here, we assessed phenotypical, transcriptional, and functional characteristics of CD1c+ and CD141+ cDC and monocytes from the blood and synovial fluid of patients with RA. Increased levels of CCR2 and the IgG receptor CD64 on circulating CD1c+ cDC was associated with the presence of this DC subset in the synovial membrane in patients with RA. Moreover, synovial CD1c+ cDC are characterized by increased expression of proinflammatory cytokines and high abilities to induce pathogenic IFN-γ+IL-17+CD4+ T cells in vitro. Finally, we identified the crosstalk between Fcγ receptors and NLRC4 as a potential molecular mechanism mediating pathogenic activation, CD64 upregulation, and functional specialization of CD1c+ cDC in response to dsDNA-IgG in patients with RA.

The emerging roles of TRIM21 in coordinating cancer metabolism, immunity and cancer treatment

Tripartite motif containing-21 (TRIM21), an E3 ubiquitin ligase, was initially found to be involved in antiviral responses and autoimmune diseases. Recently studies have reported that TRIM21 plays a dual role in cancer promoting and suppressing in the occurrence and development of various cancers. Despite the fact that TRIM21 has effects on multiple metabolic processes, inflammatory responses and the efficacy of tumor therapy, there has been no systematic review of these topics. Herein, we discuss the emerging role and function of TRIM21 in cancer metabolism, immunity, especially the immune response to inflammation associated with tumorigenesis, and also the cancer treatment, hoping to shine a light on the great potential of targeting TRIM21 as a therapeutic target.

Humoral and cellular response in convalescent COVID-19 lupus patients

In SLE, underlying immune dysregulation and immunosuppression may increase the susceptibility to COVID-19 and impair the humoral and adaptive response. We aimed to characterize COVID-19 infection, identifying susceptibility and severity risk factors, assessing the presence of SARS-CoV-2 IgG antibodies and analyzing the cellular response. We established a prospective cohort of lupus patients to estimate the COVID-19 incidence compared to the reference general population. Data were collected via telephone interviews and medical record review. SARS-CoV-2 IgG antibodies were measured cross-sectionally as part of routine surveillance. Longitudinal changes in antibody titers and immunological profile from convalescent COVID-19 patients were evaluated at 6, 12 and 24 week after symptom onset. From immunological studies, PBMCs from convalescent patients were extracted and analyzed by flow cytometry and gene expression analysis. We included 725 patients, identifying 29 with PCR-confirmed COVID-19 infection and 16 with COVID-19-like symptoms without PCR-testing. Of the 29 confirmed cases, 7 had severe disease, 8 required hospital admission (27.6%), 4 intensive care, and 1 died. COVID-19 accumulated incidence was higher in lupus patients. Health care workers and anti-SSA/Ro52 antibody positivity were risk factors for COVID-19 susceptibility, and hypocomplementemia for severity. SARS-CoV-2 IgG antibodies were detected in 8.33% of patients. Three fourths of confirmed COVID-19 cases developed antibodies. High prednisone doses were associated with lack of antibody response. Antibody titers declined over time (39%). Convalescent patients at week 12 after symptom onset displayed a CD8⁺T cell reduction and predominant Th17 with a mild Th2 response, more pronounced in severe COVID-19 disease. Longitudinal immune response analysis showed a progressive sustained increase in CD8⁺ T and B memory cells with a decrease of Th17 signaling. Lupus patients are at higher risk of COVID-19 infection and new susceptibility and severity risk factors were identified. Lupus patients were able to mount humoral and cellular responses despite immunosuppressive therapy.

Japanese Encephalitis Virus infection increases USP42 to stabilize TRIM21 and OAS1 for neuroinflammatory and anti-viral response in human microglia

Japanese Encephalitis Virus (JEV), a member virus of Flaviviridae family causes Japanese encephalitis (JE). JE is a mosquito-borne disease, spread mainly by Culex spp. During JE, dysregulated inflammatory responses play a central role in neuronal death and damage leading to Neuroinflammation. In this study, we show that JEV infection in human microglial cells (CHME3) reduces the cellular miR-590-3p levels. miR-590-3p could directly target the expression levels of USP42 (Ubiquitin Specific Peptidase 42) resulting in increased cellular levels of USP42 upon JEV infection. Our results suggest that USP42 stabilizes cellular TRIM21 via deubiquitinating them. We also established through various in vitro and in vivo experiments that increased USP42 can maintain a higher cellular level of both TRIM21 as well as OAS1. This study also suggests that TRIM21, independently of its RING domain, can increase USP42 level in a positive feedback loop and induces the cellular OAS1 levels in human microglial cells.

Epidemiologic and Etiological Features of Korean Patients With Behçet's Disease

Behçet's disease (BD) is a multisystem disease in which environmental factors provoke an adverse immune response in patients with genetic susceptibility towards BD, subsequently leading to a cascade of dysregulated inflammation throughout the body. It is particularly prevalent in regions spanning the ancient Silk Road, including Korea, where the first known case of BD was reported in 1961. We summarize the history, epidemiology, and clinical presentation of BD in Korea, highlighting the clinical tendencies that are particularly seen in the Korean BD population as compared to European populations. Analysis of epidemiologic trends over the past three decades in Korea shows a decreasing prevalence of complete BD and a higher prevalence of intestinal BD. We also discuss the ever-evolving understanding of the pathogenesis of BD, noting the complex interplay among genetics, environment, and immunology. The HLA-B51 allele is the most significant known genetic risk factor in developing BD. We also discuss more recently studied associations between BD and immune factors such as IL-10, IL-23R-IL-12RB2, IL-1A-IL-1B, CCR1, ERAP1, and the GIMAP cluster, the last of which has been found to have an association with BD specifically in Korea. Environmental factors such as pollution and microbials are often the inciting event in developing BD, as they trigger an imbalanced immune response in genetically susceptible individuals, one that has been often found to exhibit an aberrant Th1/Th17 response. There would be value to further studying the pathogenesis and clinical characteristics of Korean BD.

Manuscript Title: Analysis of tripartite motif (TRIM) family gene expression in prostate cancer bone metastases

Tripartite motif (TRIM) family proteins are post-translational protein modifiers with E3-ubiquitin ligase activity, thereby involved in various biological processes. The molecular mechanisms driving prostate cancer (PCa) bone metastasis (BM) are incompletely understood, and targetable genetic alterations are lacking in the majority of cases. Therefore, we aimed to explore the expression and potential functional relevance of 71 TRIM members in bone metastatic PCa. We performed transcriptome analysis of all human TRIM family members and 770 cancer-related genes in 29 localized PCa and 30 PCa BM using Nanostring. KEGG, STRING and Ubibrowser were used for further bioinformatic gene correlation and pathway enrichment analyses. Compared to localized tumors, six TRIMs are under-expressed while nine TRIMs are over-expressed in BM. The differentially expressed TRIM proteins are linked to TNF-, TGFβ-, PI3K/AKT- and HIF-1-signaling, and to features such as proteoglycans, platelet activation, adhesion and ECM-interaction based on correlation to cancer-related genes. The identification of TRIM-specific E3-ligase-substrates revealed insight into functional connections to oncogenes, tumor suppressors and cancer-related pathways including androgen receptor- and TGFβ signaling, cell cycle regulation and splicing. In summary, this is the first study that comprehensively and systematically characterizes the expression of all TRIM members in PCa BM. Our results describe post-translational protein modification as an important regulatory mechanism of oncogenes, tumor suppressors, and pathway molecules in PCa progression. Therefore, this study may provide evidence for novel therapeutic targets, in particular for the treatment or prevention of BM.

TRIM21 negatively regulates Corynebacterium pseudotuberculosis-induced inflammation and is critical for the survival of C. pseudotuberculosis infected C57BL6 mice

Corynebacterium pseudotuberculosis, a facultative intracellular bacterium, is an important zoonotic pathogen responsible for chronic inflammatory diseases. TRIM21, an E3 ubiquitin-protein ligase, plays pivotal roles in inflammation regulation. However, its role during C. pseudotuberculosis infection is unclear. Here, we found that TRIM21 expression was significantly increased in C. pseudotuberculosis-infected macrophages. Following infection by C. pseudotuberculosis, we observed a significantly higher number of bacteria and a higher degree of LDH release from Trim21^-/- macrophages compared to wild-type (WT) macrophages, suggesting that TRIM21 limits C. pseudotuberculosis replication in macrophages and protects the infected cells from death. Further in vivo experiments showed a significantly higher mortality, higher bacterial load, much more severe abscess formation, and lesions in the organs of C. pseudotuberculosis-infected Trim21^-/- mice compared to those of the infected WT mice, suggesting that TRIM21 plays critical roles in protecting against C. pseudotuberculosis infection. Moreover, the secretory levels of IL-1α, IL-1β, IL-6, and TNF-α were significantly higher in C. pseudotuberculosis-infected Trim21^-/- macrophages compared to infected WT macrophages; the levels of these cytokines were also higher in the sera, organs, and ascites of C. pseudotuberculosis-infected Trim21^-/- mice compared to infected WT mice. These findings suggest that TRIM21 negatively regulates the secretion of pro-inflammatory cytokines in macrophages, sera, organs, and ascites of mice following C. pseudotuberculosis infection. Collectively, the present study demonstrates that TRIM21 plays a vital role in preventing C. pseudotuberculosis infection, which may be related to the negative regulation of pro-inflammatory cytokines production by TRIM21 during this pathogen infection.

TRIM21 - A potential novel therapeutic target in cancer

Tripartite motif-containing protein 21 (TRIM21) is well known to be involved in innate immunity, systemic lupus erythematosus and Sjögren's syndrome. In addition, TRIM21 involvement in cancer proliferation has been observed. However, the clinical significance of TRIM21 and its role in cancer cell proliferation and suppression remains elusive. Here we discuss the effects of TRIM21 on major cancer promoting proteins such as NF-κB, STAT3, BCL2, p53, p27 and Snail, comparing its signaling pathways under normal conditions and in the presence of a variety of carcinogenesis effectors (oncogenic, genotoxic and UV irradiation). Depending on the cancer type and the carcinogenesis effector, TRIM21 may enhance cancer proliferation, or alternatively it may increase the ubiquitination of many cancer-triggering proteins, resulting in their proteasomal degradation. This indicates the importance of TRIM21 in cancer proliferation and/or apoptosis and suggests its potential as a novel cancer therapeutic target.

TRIM Proteins in Inflammation: from Expression to Emerging Regulatory Mechanisms

Inflammation is an immune response to exogenous or endogenous insults that helps to maintain the tissue homeostasis under stressful conditions. Depending on the differential types of insults, inflammation is classified into microbial, autoimmune, metabolic, allergic, and physical inflammation. With regard to its involvement in the pathogenesis of most of human diseases, dissecting the key molecules in the regulation of inflammatory process is vital for the prevention and therapeutics of human diseases. Tripartite motif (TRIM) proteins are a versatile family of E3 ligases, which are composed of > 80 distinct members in humans recognized for their roles in antiviral responses. Recently, a large number of studies have shown the regulatory roles of TRIM proteins in mediating the inflammation. Herein in this review, we discuss the aberrations of TRIM proteins in autoimmune and autoinflammatory diseases, with a focus on the regulation of different components of inflammatory process, including inflammasome, NF-κB signaling, type I IFN (interferon) production, and Th1/Th17 cell differentiation. Importantly, elucidation of the mechanism underlying the regulation of inflammation by TRIMs provides insights into the use of TRIMs as therapeutic targets for disease treatment.

Auto-antibody evaluation in idiopathic interstitial pneumonia and worse survival of patients with Ro52/TRIM21auto-antibody

Some patients with interstitial pneumonia (IP) have auto-antibodies, but do not fit the criteria for specific connective tissue diseases. Examination of auto-antibodies is recommended for diagnosis idiopathic pulmonary fibrosis. A prospective cohort study was performed in 285 patients with IP. Eleven auto-antibodies were assessed and patients were followed for 2 years. All 285 patients underwent the myositis panel test (MPT) for 11 auto-antibodies. Among them, 23.5% (67/285) of the patients had a positive MPT and 14.7% (42/285) had connective tissue diseases. Among the 49 MPT positive patients without connective tissue diseases, 29 patients (59.2%) were positive for Ro52, including 17 patients with Ro52 mono-positivity. Among interstitial pneumonia patients without connective tissue diseases, the Ro52 mono-positive patients showed worse at 2-years survival than those who were Ro52 negative (p = 0.022, HR = 5.88, 95% CI 1.29–26.75). Most of the Ro52 positive patients also showed a low titer of anti-nucleolar antibody. About 20% of IP patients had auto-antibodies detectable by the MPT, and Ro52 positive patients accounted for more than half of the MPT positive patients without connective tissue diseases. Detection of Ro52 auto-antibodies may be useful for assessing the risk of progression in idiopathic interstitial pneumonia patients without connective tissue diseases and a low anti-nucleolar antibody titer.

CIP2A Constrains Th17 Differentiation by Modulating STAT3 Signaling

Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A) is an oncogene and a potential cancer therapy target protein. Accordingly, a better understanding of the physiological function of CIP2A, especially in the context of immune cells, is a prerequisite for its exploitation in cancer therapy. Here, we report that CIP2A negatively regulates interleukin (IL)-17 production by Th17 cells in human and mouse. Interestingly, concomitant with increased IL-17 production, CIP2A-deficient Th17 cells had increased strength and duration of STAT3 phosphorylation. We analyzed the interactome of phosphorylated STAT3 in CIP2A-deficient and CIP2A-sufficient Th17 cells and indicated together with genome-wide gene expression profiling, a role of Acylglycerol Kinase (AGK) in the regulation of Th17 differentiation by CIP2A. We demonstrated that CIP2A regulates the strength of the interaction between AGK and STAT3, and thereby modulates STAT3 phosphorylation and expression of IL-17 in Th17 cells.

To TRIM the Immunity: From Innate to Adaptive Immunity

The tripartite motif (TRIM) proteins have been intensively studied as essential modulators in various biological processes, especially in regulating a wide range of signaling pathways involved in immune responses. Most TRIM proteins have E3 ubiquitin ligase activity, mediating polyubiquitination of target proteins. Emerging evidence demonstrates that TRIM proteins play important roles in innate immunity by regulating pattern recognition receptors, vital adaptor proteins, kinases, and transcription factors in innate immune signaling pathways. Additionally, the critical roles of TRIM proteins in adaptive immunity, especially in T cell development and activation, are increasingly appreciated. In this review, we aim to summarize the studies on TRIMs in both innate and adaptive immunity, focusing on their E3 ubiquitin ligase functions in pattern recognition receptor signaling pathways and T cell functions, shedding light on the developing new strategies for modulating innate and adaptive immune responses against invading pathogens and avoiding autoimmunity.

Endoglin Protein Interactome Profiling Identifies TRIM21 and Galectin-3 as New Binding Partners

Endoglin is a 180-kDa glycoprotein receptor primarily expressed by the vascular endothelium and involved in cardiovascular disease and cancer. Heterozygous mutations in the endoglin gene (ENG) cause hereditary hemorrhagic telangiectasia type 1, a vascular disease that presents with nasal and gastrointestinal bleeding, skin and mucosa telangiectases, and arteriovenous malformations in internal organs. A circulating form of endoglin (alias soluble endoglin, sEng), proteolytically released from the membrane-bound protein, has been observed in several inflammation-related pathological conditions and appears to contribute to endothelial dysfunction and cancer development through unknown mechanisms. Membrane-bound endoglin is an auxiliary component of the TGF-β receptor complex and the extracellular region of endoglin has been shown to interact with types I and II TGF-β receptors, as well as with BMP9 and BMP10 ligands, both members of the TGF-β family. To search for novel protein interactors, we screened a microarray containing over 9000 unique human proteins using recombinant sEng as bait. We find that sEng binds with high affinity, at least, to 22 new proteins. Among these, we validated the interaction of endoglin with galectin-3, a secreted member of the lectin family with capacity to bind membrane glycoproteins, and with tripartite motif-containing protein 21 (TRIM21), an E3 ubiquitin-protein ligase. Using human endothelial cells and Chinese hamster ovary cells, we showed that endoglin co-immunoprecipitates and co-localizes with galectin-3 or TRIM21. These results open new research avenues on endoglin function and regulation.

Enhanced T-cell proliferation and IL-6 secretion mediated by overexpression of TRIM21 in oral lesions of patients with oral lichen planus

BACKGROUNDS

To explore the expression and functions of the tripartite motif-containing protein 21 (TRIM21) in oral lichen planus(OLP) lesions.

METHODS

Paraffin sections of buccal mucosa samples from 15 cases of reticular oral lichen planus (OLP) patients and 10 healthy controls were used for immunohistochemistry to determine expression and distribution of TRIM21. Buccal mucosae from 11 OLP patients and seven healthy controls were analyzed by qPCR to quantify its gene expression. Peripheral blood mononuclear cells and CD3+ cells from four pairs of age- and sex-matched OLP patients and healthy controls were isolated for immunocytochemistry and culture. Following lentivirus-mediated overexpression of TRIM21 gene in CD3+ cells, CCK-8 was applied to evaluate cell proliferation. Cytokines including IL-2, IL-4, IL-5, IL-6, IL-10, TNF-α, and IFN-γ in the supernatants were measured by the cytometric bead array and verified by ELISA.

RESULTS

A larger number of TRIM21-positive cells infiltrating the lamina propria were observed in OLP lesions by immunohistochemistry than those of healthy controls. Significantly higher transcription of TRIM21 was revealed by qPCR. TRIM21 overexpression in CD3+ cells significantly enhanced the proliferation and IL-6 secretion in CD3+ cells from 12 to 72 hours.

CONCLUSION

Overexpressed TRIM21 in OLP may be a primary proinflammatory molecule rather than a secondary and inducible regulatory factor in immunopathogenesis of OLP.