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Patients with tumour necrosis factor-receptor associated periodic syndrome (TRAPS) demonstrate LPS-induced XBP1 splicing which is abolished by antioxidant treatment. XBP1 splicing was measured using quantitative PCR. Peripheral blood mononuclear cells from healthy controls (HCs) (n=5) and patients with TRAPS (n=7) were cultured for 6 h (lipopolysaccharide (LPS) 10 ng/ml, diphenyleneiodonium chloride (DPI) 5 μM), and levels of uXBP1 and sXBP1 measured. Data are plotted as relative expression units (REU); expression of the transcript relative to hypoxanthine phosphoribosyltransferase 1 (HPRT) using the 2 (– Δ Ct) method. (A) HC uXBP1 ; (B) HC sXBP1 ; (C) TRAPS uXBP1 and (D) TRAPS sXBP1 . A Kruskal–Wallis test with Dunn’s multiple comparison correction was carried out to analyse signifi cant differences between the groups (*p<0.05, **p<0.01).
Source publication
Objectives To investigate convergence of endoplasmic reticulum stress pathways and enhanced reactive oxygen species (ROS) production, due to intracellular retention of mutant tumour necrosis factor receptor 1 (TNFR1), as a disease mechanism in TNFR-associated periodic syndrome (TRAPS).
Methods Peripheral blood mononuclear cells from patients with T...
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Background
Endoplasmic reticulum (ER) stress and the subsequent unfolded protein response may initially be protective, but when prolonged, have been implicated in atherogenesis in diabetic conditions. Triglycerides and free fatty acids (FFAs) are elevated in patients with diabetes and may contribute to ER stress. We sought to evaluate the effect of...
Citations
... The most representative protein misfolding disorder is TNFR-associated periodic syndrome (TRAPS) caused by one of nine possible mutations in TNFRSF1A, resulting in protein misfolding of the TNFR1. The pathogenic mechanism is still mostly unknown, but the abnormal oligomerized TNFR and its retained in the ER suggests that a UPR response may also be induced [60]. PBMCs from TRAPS patients show some evidence of a UPR. ...
Dysregulation and hyperactivation of innate immune responses can lead to the onset of systemic autoinflammatory diseases. Monogenic autoinflammatory diseases are caused by inborn genetic errors and based on molecular mechanisms at play, can be divided into inflammasomopathies, interferonopathies, relopathies, protein misfolding, and endogenous antagonist deficiencies. On the other hand, more common autoinflammatory diseases are multifactorial, with both genetic and non‐genetic factors playing an important role. During the last decade, long‐term memory characteristics of innate immune responses have been described (also called trained immunity) that in physiological conditions provide enhanced host protection from pathogenic re‐infection. However, if dysregulated, induction of trained immunity can become maladaptive, perpetuating chronic inflammatory activation. Here, we describe the mechanisms of genetic and epigenetic dysregulation of the innate immune system and maladaptive trained immunity that leads to the onset and perpetuation of the most common and recently described systemic autoinflammatory diseases.
... It is widely accepted that ROS serves as the primary trigger for NLRP3 inflammasome activation [32], consequently promoting the development of chronic inflammation and fibroplasia. This activation of HSCs ultimately leads to the progression of fibrosis [33,34]. Furthermore, the induction of oxidative stress plays a substantial role in HSC activation and fibrosis [35]. ...
... Macrophages of TNFR1-mutant mice produce more IL-6 in response to lipopolysaccharides than wild-type macrophages [30]. IL-6 can trigger ROS production in monocytes from TRAPS patients [31]. IL-6 production decreases after ROS inhibition. ...
Background
Mevalonate kinase deficiency (MKD) and TNF receptor-associated periodic syndrome (TRAPS) are categorized as systemic autoinflammatory diseases (SAIDs), which are rare diseases characterized by early onset, severe conditions, and challenging diagnosis and treatment. Although different SAIDs have varying standard treatments, some SAIDs are poorly controlled after routine treatment, seriously affecting the growth and development of children and their quality of life. This study aims to provide more treatment strategies for SAIDs.
Case presentation
We present two Chinese patients with MKD and TRAPS who were resistant to TNF- (tumor necrosis factor-) α blockade. After using etanercept, baricitinib, and glucocorticoid, patients with MKD and TRAPS still had periodic fever and rash. Due to the unavailability of IL-1 antagonists in the Chinese Mainland, we started administering intravenous tocilizumab (TCZ) at a dosage of 240 mg every three weeks. They had not experienced fever or rash after receiving one or two doses of TCZ. Before treatment with TCZ in the MKD patient, white blood cell (WBC) count, and TNF-α level were normal, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) increased significantly, and IL-6 increased slightly. After treatment with TCZ, ESR and CRP levels returned to normal; however, IL-6 increased occasionally. In the TRAPS patient, ESR, CRP, WBC, IL-6, and TNF-α levels were increased significantly. After TCZ treatment, ESR, CRP, WBC, IL-6, and TNF-α levels returned to normal. The two patients were treated with TCZ for more than six months and achieved clinical and serological remission. Furthermore, they had no adverse reactions after injection of TCZ.
Conclusion
In the absence of IL-1 antagonists in mainland China, tocilizumab emerges as an alternative drug in SAIDs that are resistant to TNF-α blockade.
... When misfolded proteins accumulate in the endoplasmic reticulum (ER) of chondrocytes, endoribonuclease is triggered to produce XBP1 by non-conventional splicing of XBP1 messenger RNA, thereby inducing apoptosis and transcription of unfolded protein response target genes [45]. XBP1 relies on NADPH oxidase 2 and is required for proinflammatory cytokine responses in macrophages [46]. TLR signaling-simulated inflammatory responses in rheumatoid arthritis synovial fibroblasts undergoing ER stress may be attenuated by silencing XBP-1. ...
Background
Ankylosing spondylitis (AS) is a disabling chronic inflammatory disease. Mechanisms of ferroptosis in AS remain unclear. Using bioinformatics analysis, we aimed to identify key molecules involved in ferroptosis, provide potential therapeutic targets for AS, and further explore mechanisms of ferroptosis in AS.
Methods
GSE25101 was downloaded from the Gene Expression Omnibus and intersected with a ferroptosis gene dataset. The ferroptosis‐relate differentially‐expressed genes were further subjected to functional enrichment analysis, protein interaction network analysis, and gene‐miRNA interaction network analysis, from which potential key ferroptosis genes in the pathogenesis of ankylosing spondylitis were screened.
Results
A total of 20 differentially expressed genes were screened, most of which are involved in phosphoinositide 3 kinase‐Akt or mitogen‐activated protein kinase (MAPK) signaling pathways or the endoplasmic reticulum stress response. The following target genes were identified through protein‐protein interaction network analysis and screening of key modules constructed from genes associated with PI3K‐Akt and MAPK signaling pathways: TP53, PTEN, TLR4, HSPB1, DDIT3, and XBP1. In addition, PI3K‐Akt and MAPK signaling were associated with oxidative stress, which may play a role in AS pathological ossification related to ferroptosis. Only hsa‐miR‐205‐5p was found to target at least two genes by gene‐miRNA interaction network analysis.
Conclusions
Future therapeutic drug development may intervene by modulating MAPK or PI3K‐Akt signaling pathways rather than directly affecting the interleukin 17 pathway. hsa‐miR‐205‐5p may be a potential novel biomarker for AS.
... Since TRAPS mutations affect the cell surface expression of TNFR1 in overexpression models (2,4,6,27), we assessed the cell surface expression of TNFR1 in peritoneal macrophages using flow cytometry. We found that the cell surface levels of FIGURE 4 No substantial changes in LPS-induced activation of MAPK and NF-kB pathways by the TRAPS mutations. ...
... T79M and G87V TRAPS mutations decreased the cell surface expression of TNFR1 in macrophages. This finding is consistent with previous studies on TRAPS-mutant TNFR1 overexpressing cells (4,5,27). We also found that sTNFR1 levels were not increased in the culture supernatant of mutant macrophages or in the sera of mutant mice. ...
... These findings suggest the TNFR1 protein accumulated in the cytoplasm of the cells. Indeed, intracellular accumulation has been reported in mutant TNFR1 overexpressing cell models (5,27). Furthermore, previous studies have shown aberrant accumulation of TNFR1 in the ER, and it has been proposed that ER stress induces MAPK activation at baseline and predisposes the cells to inflammation (5, 33). ...
Tumor necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS) is an autoinflammatory periodic fever syndrome associated with heterozygous mutations in TNFRSF1A, which encodes TNF receptor type I (TNFR1). Although possible proinflammatory mechanisms have been proposed, most previous studies were performed using in vitro overexpression models, which could lead to undesirable inflammatory responses due to artificial overexpression. It is crucial to reproduce heterozygous mutations at physiological expression levels; however, such studies remain limited. In this study, we generated TRAPS mutant mice and analyzed their phenotypes. Three Tnfrsf1a mutant strains were generated by introducing T79M, G87V, or T90I mutation. T79M is a known mutation responsible for TRAPS, whereas G87V is a TRAPS mutation that we have reported, and T90I is a variant of unknown significance. Using these murine models, we investigated whether TRAPS mutations could affect the inflammatory responses in vivo and in vitro. We found that none of the mutant mice exhibited detectable inflammatory phenotypes under standard housing conditions for 1 year. Interestingly, TRAPS mutant (T79M and G87V) mice had reduced mortality rates after the administration of lipopolysaccharide (LPS) and D-galactosamine, which induce TNFα-dependent lethal hepatitis. Moreover, TRAPS mutations strongly suppressed the development of TNFα-mediated arthritis when crossed with human TNFα transgenic mice. In in vitro primary bone marrow-derived macrophage cultures, the T79M and G87V mutations attenuated the inflammatory responses to TNFα compared with the wild-type, whereas these mutations did not alter the responsiveness of these cells to LPS. The T90I mutant macrophages behaved similarly to wild type in response to LPS and TNFα. The TNFR1 levels were increased in whole-cell lysates of TRAPS mutant macrophages, whereas the cell surface expression of TNFR1 was significantly decreased in TRAPS mutant macrophages. Taken together, TRAPS mutations did not augment the inflammatory responses to TNFα and LPS; instead, they suppressed the response to TNFα via decreased cell surface expression of TNFR1. The stimulation of lymphotoxin-α, adenosine triphosphate, and norepinephrine in primary macrophages or various stimuli in murine splenocytes did not induce detectable inflammatory responses. In conclusion, TRAPS mutations suppressed responsiveness to TNFα, and TRAPS-associated inflammation is likely induced by unconfirmed disease-specific proinflammatory factors.
... 182 Mutated variants of TNFR1 also induce atypical ER stress and unfolded protein response (UPR) transcriptomic signature. 183 This is likely to result in NLRP3 activation, as ER-retained TNFR1 can recruit the ER stress sensor, IRE1a, an essential UPR effector 184 whose inhibition prevents NLRP3 activation. 185,186 Indeed, IRE1a can promote NLRP3 inflammasome assembly by damaging mitochondria via caspase-2 and Bid activation. ...
Inflammasomes are assembled by innate immune sensors that cells employ to detect a range of danger signals and respond with pro-inflammatory signalling. Inflammasomes activate inflammatory caspases, which trigger a cascade of molecular events with the potential to compromise cellular integrity and release the IL-1β and IL-18 pro-inflammatory cytokines. Several molecular mechanisms, working in concert, ensure that inflammasome activation is tightly regulated; these include NLRP3 post-translational modifications, ubiquitination and phosphorylation, as well as single-domain proteins that competitively bind to key inflammasome components, such as the CARD-only proteins (COPs) and PYD-only proteins (POPs). These diverse regulatory systems ensure that a suitable level of inflammation is initiated to counteract any cellular insult, while simultaneously preserving tissue architecture. When inflammasomes are aberrantly activated can drive excessive production of pro-inflammatory cytokines and cell death, leading to tissue damage. In several autoinflammatory conditions, inflammasomes are aberrantly activated with subsequent development of clinical features that reflect the degree of underlying tissue and organ damage. Several of the resulting disease complications may be successfully controlled by anti-inflammatory drugs and/or specific cytokine inhibitors, in addition to more recently developed small-molecule inhibitors. In this review, we will explore the molecular processes underlying the activation of several inflammasomes and highlight their role during health and disease. We also describe the detrimental effects of these inflammasome complexes, in some pathological conditions, and review current therapeutic approaches as well as future prospective treatments.
... According to a previous study, mitochondrial ROS is the main activator of the NLRP3 inflammasome (Scambler et al., 2019). ROS can induce chronic inflammation and fibrous hyperplasia, leading to the activation of HSCs and finally promoting fibrosis (Dickie et al., 2012;Chen et al., 2019). In addition, oxidative stress significantly FIGURE 5 | Deficiency of ERβ, but not ERα, blocked the inhibitory effect of SSd against CCL 4 -induced liver injury (A,B) plasma ALT and AST levels were tested after CCl 4 treatment in WT and ERKO mice treated with SSd or without SSd, n = 6. ...
Background and aims: Saikosaponin d (SSd) has a steroidal structure and significant anti-inflammatory effects. The purpose of this study was to explore the mechanism underlying SSd’s inhibitory effects on liver fibrosis.
Methods: Wild-type and estrogen receptor knockout (ERKO) mice were treated with CCl4 to establish liver fibrosis mouse models. The effects of SSd on hepatic fibrogenesis were studied in these mouse models. Hepatic stellate cells (HSCs) were activated by H2O2 to investigate the potential molecular mechanisms. The establishment of the models and the degrees of inflammation and liver tissue fibrosis were evaluated by detecting changes in serum liver enzymes and liver histopathology. The expression of α-SMA and TGF-β1 was determined by immunohistochemistry. The expression and significance of NLRP3 inflammasome proteins were explored by RT-PCR and Western blotting analyses. The mitochondrial ROS-related indexes were evaluated by MitoSOX Red.
Results: In wild-type and ERKO mice treated with CCl4, the fluorescence expression of mitochondrial ROS was up-regulated, while the mitochondrial membrane potential and ATP content were decreased, suggesting that the mitochondria were damaged. In addition, the expression of NLRP3 inflammatory bodies and fibrosis markers (α-SMA, TGF-β, TIMP-1, MMP-2, and Vimentin) in liver tissue increased. Furthermore, the above indexes showed the same expression trend in activated HSCs. In addition, the peripheral serum ALT and AST levels increased in CCl4-induced liver injury model mice. And HE staining showed a large number of inflammatory cell infiltration in the liver of model mice. Picric acid-Sirius staining and Masson staining showed that there was significant collagen fibrous tissue deposition in mice liver sections. IHC and WB detection confirmed that the expression of α-SMA and TGF-β1 increased. Liver fibrosis scores were also elevated. Then, after SSd intervention, the expression of ROS in wild-type mice and αERKO mice decreased, mitochondrial membrane potential recovered, ATP level increased, NLRP3 inflammasome and fibrosis indexes decreased, liver enzyme levels decreased, and liver pathology showed liver inflammation. The damage and collagen deposition were significantly relieved, the expression of α-SMA and TGF-β1 was decreased, and the fibrosis score was also decreased. More importantly, the effect of SSd in alleviating liver injury and liver fibrosis had no effect on βERKO mice.
Conclusion: SSd alleviated liver fibrosis by negatively regulating the ROS/NLRP3 inflammasome through activating the ERβ pathway. By establishing liver fibrosis models using wild-type and ERKO mice, we demonstrated that SSd could alleviate liver fibrosis by inhibiting the ROS/NLRP3 inflammasome axis through activating the ERβ pathway.
... TRAPS patients carrying the p.(Thr79Met) disease-causing variant have a severe phenotype, with disease refractory to therapy such as infliximab 53 or anakinra 54 . In addition, TRAPS cells carrying p.(Thr79Met) show reduced TNFR1 receptor shedding 20,23,55 , hyper-responsiveness to lipopolysaccharide [56][57][58] , inappropriate cellular stress leading to reactive oxygen species production 49,56,59 and aberrant NF-κB activation. The defective TNFR1-mediated NF-κB activation seems to be subunit-specific because only the NF-κB p65 subunit level is increased in peripheral blood mononuclear cells (PBMCs) from patients, whereas the level of the basal or TNFα-induced NF-κB p50 subunit is comparable to that in PBMCs from healthy controls 55 . ...
Binding of tumour necrosis factor α (TNFα) to its receptor (TNFR1) is critical for both survival and death cellular pathways. TNFα/TNFR1 signalling is complex and tightly regulated at different levels to control cell fate decisions. Previously, we identified TNFR1-d2, an exon 2-spliced transcript of TNFRSF1A gene encoding TNFR1, whose splicing may be modulated by polymorphisms associated with inflammatory disorders. Here, we investigated the impact of TNFRSF1A variants involved in TNFR-associated periodic syndrome (TRAPS) on TNFR1-d2 protein expression and activity. We found that TNFR1-d2 could be translated by using an internal translation initiation codon and a de novo internal ribosome entry site (IRES), which resulted in a putative TNFR1 isoform lacking its N-terminal region. The kinetic of assembly of TNFR1-d2 clusters at the cell surface was reduced as compared with full-length TNFR1. Although co-localized with the full-length TNFR1, TNFR1-d2 neither activated nuclear factor (NF)-κB signalling, nor interfered with TNFR1-induced NF-κB activation. Translation of TNFR1-d2 carrying the severe p.(Thr79Met) pathogenic variant (also known as T50M) was initiated at the mutated codon, resulting in an elongated extracellular domain, increased speed to form preassembled clusters in absence of TNFα, and constitutive NF-κB activation. Overall, TNFR1-d2 might reflect the complexity of the TNFR1 signalling pathways and could be involved in TRAPS pathophysiology of patients carrying the p.(Thr79Met) disease-causing variant.
... Interestingly, it has been previously hypothesised that the chronically raised levels of pro-inflammatory cytokines might result in metabolic disturbances during the pathogenesis of CF [193,194]. Certainly, this is the case in other immune conditions, where the excessive levels of pro-inflammatory cytokines, as well as other intrinsic cellular abnormalities, contribute to the induction of cellular stress, which is directly associated with disruption of cellular metabolism [195][196][197][198]. It would be interesting to investigate the effects of the increased levels of pro-inflammatory cytokines, present in patients with CF, concerning glycolytic and mitochondrial metabolism. ...
Cystic fibrosis (CF) is one of the most common life-limiting recessive genetic disorders in Caucasians, caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR). CF is a multi-organ disease that involves the lungs, pancreas, sweat glands, digestive and reproductive systems and several other tissues. This debilitating condition is associated with recurrent lower respiratory tract bacterial and viral infections, as well as inflammatory complications that may eventually lead to pulmonary failure. Immune cells play a crucial role in protecting the organs against opportunistic infections and also in the regulation of tissue homeostasis. Innate immune cells are generally affected by CFTR mutations in patients with CF, leading to dysregulation of several cellular signalling pathways that are in continuous use by these cells to elicit a proper immune response. There is substantial evidence to show that airway epithelial cells, neutrophils, monocytes and macrophages all contribute to the pathogenesis of CF, underlying the importance of the CFTR in innate immune responses. The goal of this review is to put into context the important role of the CFTR in different innate immune cells and how CFTR dysfunction contributes to the pathogenesis of CF, highlighting several signalling pathways that may be dysregulated in cells with CFTR mutations.
... The structurally altered mutant of TNFR-I failed to interact with the wild-type receptor and formed abnormal self-aggregates that were retained in the endoplasmic reticulum. Misfolding of TNFR-I in the ER induces an inflammatory response through the unfolded protein reticulum (8), ligand-independent NFκB activation (9-11), and generation of mitochondrial reactive oxygen species (12). This misfolding hypothesis might explain how the inflammatory phenotype of TRAPS may be associated with the induction of cytokines, such as IL-1β, due to an unfolded protein response. ...
Objectives: Genetic analysis of TNFRSF1A can confirm the diagnosis of tumor necrosis factor receptor-associated periodic syndrome (TRAPS), but interpretation of the pathogenesis of variants of unknown significance is sometimes required. The aim of this study was to evaluate the clinical significance of serum soluble tumor necrosis factor receptor type I (sTNFR-I)/II ratio to differentiate TRAPS from other autoinflammatory diseases.
Methods: Serum sTNFR-I and sTNFR-II levels were measured using an enzyme-linked immunosorbent assay in patients with TRAPS (n = 5), familial Mediterranean fever (FMF) (n = 14), systemic juvenile idiopathic arthritis (s-JIA) (n = 90), and Kawasaki disease (KD) (n = 37) in the active and inactive phase, along with healthy controls (HCs) (n = 18).
Results: In the active phase, the serum sTNFR-I/II ratio in patients with s-JIA, KD, and FMF was significantly elevated compared with that in HCs, whereas it was not elevated in patients with TRAPS. In the inactive phase, the serum sTNFR-I/II ratio in patients with s-JIA and FMF was significantly higher compared with that in HCs, and the ratio was lower in TRAPS patients than in patients with s-JIA and FMF.
Conclusions: Low serum sTNFR-I/II ratio in the active and inactive phase might be useful for the differential diagnosis of TRAPS and other autoinflammatory diseases.
