Teuvincenone F Suppresses LPS-Induced Inflammation and NLRP3 Inflammasome Activation by Attenuating NEMO Ubiquitination

Targeting epigenetic and post-translational modifications regulating pyroptosis for the treatment of inflammatory diseases

Inflammatory diseases, including infectious diseases, diabetes-related diseases, arthritis-related diseases, neurological diseases, digestive diseases, and tumor, continue to threaten human health and impose a significant financial burden despite advancements in clinical treatment. Pyroptosis, a pro-inflammatory programmed cell death pathway, plays an important role in the regulation of inflammation. Moderate pyroptosis contributes to the activation of native immunity, whereas excessive pyroptosis is associated with the occurrence and progression of inflammation. Pyroptosis is complicated and tightly controlled by various factors. Accumulating evidence has confirmed that epigenetic modifications and post-translational modifications (PTMs) play vital roles in the regulation of pyroptosis. Epigenetic modifications, which include DNA methylation and histone modifications (such as methylation and acetylation), and post-translational modifications (such as ubiquitination, phosphorylation, and acetylation) precisely manipulate gene expression and protein functions at the transcriptional and post-translational levels, respectively. In this review, we summarize the major pathways of pyroptosis and focus on the regulatory roles and mechanisms of epigenetic and post-translational modifications of pyroptotic components. We also illustrate these within pyroptosis-associated inflammatory diseases. In addition, we discuss the effects of novel therapeutic strategies targeting epigenetic and post-translational modifications on pyroptosis, and provide prospective insight into the regulation of pyroptosis for the treatment of inflammatory diseases.

Dysregulated inflammasome activity in intestinal inflammation - Insights from patients with very early onset IBD

Inflammatory bowel disease (IBD) is a multifactorial disorder triggered by imbalances of the microbiome and immune dysregulations in genetically susceptible individuals. Several mouse and human studies have demonstrated that multimeric inflammasomes are critical regulators of host defense and gut homeostasis by modulating immune responses to pathogen- or damage-associated molecular patterns. In the context of IBD, excessive production of pro-inflammatory Interleukin-1β has been detected in patient-derived intestinal tissues and correlated with the disease severity or failure to respond to anti-tumor necrosis factor therapy. Correspondingly, genome-wide association studies have suggested that single nucleotide polymorphisms in inflammasome components might be associated with risk of IBD development. The relevance of inflammasomes in controlling human intestinal homeostasis has been further exemplified by the discovery of very early onset IBD (VEO-IBD) patients with monogenic defects affecting different molecules in the complex regulatory network of inflammasome activity. This review provides an overview of known causative monogenic entities of VEO-IBD associated with altered inflammasome activity. A better understanding of the molecular mechanisms controlling inflammasomes in monogenic VEO-IBD may open novel therapeutic avenues for rare and common inflammatory diseases.

Selenium Ameliorates S. aureus-Induced Inflammation in Bovine Mammary Epithelial Cells by Regulating ROS-Induced NLRP3 Inflammasome

In this study, the regulation effects of selenium (Se) on the expression of pyrin domain-containing protein (NLRP) 3 inflammasome and reactive oxygen species (ROS) in bovine mammary epithelial cells (bMECs) infected by Staphylococcus aureus (S. aureus) were detected. bMECs were treated with 8 μmol/L Na₂SeO₃ for 12 h before infection with S. aureus for 2 h. Through flow cytometry, Western blot, and qRT-PCR analysis, the expression of ROS and NLRP3 imflammasome was detected. Results showed Se significantly reduced the ROS level in bMECs; at the same time, the expressions of NLRP3, ASC, caspase-1, Pro-IL-1β, and IL-1β were also decreased. In conclusion, Se inhibits S. aureus-induced inflammation by suppressing the activation of NLRP3 inflammasome and ROS in bMECs.

Selenium Attenuates S. aureus-Induced Inflammation by Regulation TLR2 Signaling Pathway and NLRP3 Inflammasome in RAW 264.7 Macrophages

This study aimed to investigate the effects of selenium (Se) on the expression of Toll-like receptor (TLR) 2 and pyrin domain-containing protein (NLRP)3 inflammasome in macrophages infected by Staphylococcus aureus (S. aureus). RAW 264.7 macrophages were treated with 2 μmol/L Na₂SeO₃ for 12 h before infection with S. aureus for 2 h. Through Western blot, qRT-PCR, and ELISA analysis, the core molecules of TLR2 signaling pathway and NLRP3 inflammasome in RAW 264.7 macrophages were detected. Results showed that Se significantly reduced the elevated mRNA expression of TLR2, myeloid differentiation factor-88 (Myd88), NLRP3, Caspase-recruitment domain (ASC), and Caspase-1 induced by S. aureus. Furthermore, compared with I group, the protein expression of TLR2, Myd88, NLRP3, ASC, and Caspase-1 were suppressed in T group. In addition, the mRNA and protein expression of interleukin-1 beta (IL-1β) induced by S. aureus were also decreased after Se treatment. In conclusion, Se inhibits S. aureus-induced inflammation by suppressing the activation of the TLR2 signaling pathway and NLRP3 inflammasome in RAW 264.7 macrophages.

Modulatory Properties of Food and Nutraceutical Components Targeting NLRP3 Inflammasome Activation

Inflammasomes are key intracellular multimeric proteins able to initiate the cellular inflammatory signaling pathway. NLRP3 inflammasome represents one of the main protein complexes involved in the development of inflammatory events, and its activity has been largely demonstrated to be connected with inflammatory or autoinflammatory disorders, including diabetes, gouty arthritis, liver fibrosis, Alzheimer’s disease, respiratory syndromes, atherosclerosis, and cancer initiation. In recent years, it has been demonstrated how dietary intake and nutritional status represent important environmental elements that can modulate metabolic inflammation, since food matrices are an important source of several bioactive compounds. In this review, an updated status of knowledge regarding food bioactive compounds as NLRP3 inflammasome modulators is discussed. Several chemical classes, namely polyphenols, organosulfurs, terpenes, fatty acids, proteins, amino acids, saponins, sterols, polysaccharides, carotenoids, vitamins, and probiotics, have been shown to possess NLRP3 inflammasome-modulating activity through in vitro and in vivo assays, mainly demonstrating an anti-NLRP3 inflammasome activity. Plant foods are particularly rich in important bioactive compounds, each of them can have different effects on the pathway of inflammatory response, confirming the importance of the nutritional pattern (food model) as a whole rather than any single nutrient or functional compound.

USP19 (ubiquitin specific peptidase 19) promotes TBK1 (TANK-binding kinase 1) degradation via chaperone-mediated autophagy

TBK1 (TANK-binding kinase 1) is an essential receptor protein required for the innate immune response, but the mechanisms underlying TBK1 stability, especially those regulated via autophagy, remain poorly understood. Here, we demonstrate that USP19 (ubiquitin specific peptidase 19) interacts with and promotes TBK1 lysosomal degradation via chaperone-mediated autophagy (CMA). We observed that TBK1 had a canonical CMA motif, knocking down key proteins involved in CMA (HSPA8/HSC70 or LAMP2A) or inhibiting CMA-prevented USP19-mediated TBK1 degradation. Furthermore, USP19 deficiency in macrophages caused an elevation of TBK1 and the activation of the type-I interferon signaling pathway after vesicular stomatitis virus (VSV) infection. Consistently, macrophage-specific usp19 knockout in mice resulted in attenuated VSV replication and resistance to VSV infection in vivo. Altogether, our results suggest that USP19 is a key regulator of TBK1 and uncovers a previously uncharacterized role for USP19 in CMA-mediated TBK1 degradation and infectious diseases.

Selenium Plays an Anti-Inflammatory Role by Regulation NLRP3 Inflammasome in Staphylococcus aureus-Infected Mouse Mammary Gland

Selenium is an essential micronutrient that plays an important role in immunity. However, the mechanism that Selenium modulates mastitis is not fully clear. In this experiment, we investigated whether selenium can inhibit the activation of the NLRP3 inflammasome in a mouse model of Staphylococcus aureus-induced mastitis. Eighty BALB/c female mice were fed with experimental Selenium deficiency basal diet for 2 weeks to achieve the purpose of selenium consumption until pregnancy. Pregnant mice were randomly divided into four groups (control group; selenium supplement group; Staphylococcus aureus infection group and Staphylococcus aureus infection after selenium supplement group). Twenty-four hours after challenging, all mice were euthanized and mammary tissue samples were aseptically collected. Through pathological staining, western blot analysis, real-time fluorescence quantitative polymerase chain reaction analysis, and enzyme-linked immunosorbent assay, the regulation effect of Selenium on NLRP3 inflammasome was detected. The result showed that compared with the control group, selenium significantly inhibited the expression of NLRP3, ASC, Caspase-1, Caspase-1 p20, and Pro-IL-1β (p < 0.01). Meanwhile the mRNA expression and release of IL-1β was suppressed in the treatment group compared with Staphylococcus aureus infection group (p < 0.01). Therefore, these results suggest that dietary selenium can attenuate Staphylococcus aureus mastitis by inhibition of the NLRP3 inflammasome.

Novel clerodane-type diterpenoid Cintelactone A suppresses lipopolysaccharide -induced inflammation by promoting ubiquitination, proteasomal degradation of TRAF6

Cellular inflammation is the underlying cause of several diseases and development of a safe and effective anti-inflammatory drug is need-of-the hour for treatment of diseases like lung inflammation. Callicarpa integerrima Champ. is a well-known herbal medicine with hemostatic and anti-inflammatory functions. However, the exact ingredient exhibiting anti-inflammatory activity in C. integerrima Champ. is largely unknown. Here, we first isolated, purified and characterized a novel clerodane-type diterpenoid Cintelactone A (CA) from C. integerrima Champ. We demonstrated that CA could significantly inhibit lipopolysaccharide (LPS)-induced pro-inflammatory cytokines and mediators production both in mouse peritoneal macrophages and THP1 cells. Consistently, CA also relieved inflammation and reduced LPS-induced lung injury in mice. We systematically elucidated the mechanism of action as well. CA interacted with Arg78 of tumor necrosis factor receptor-associated factor 6 (TRAF6) by hydrogen bonding. It further promoted the K48-linked ubiquitination and proteasomal degradation of TRAF6, and suppressed the activation of NF-κB and MAPKs signaling pathways. Collectively, our study reveals that new clerodane-type diterpenoid CA suppresses LPS-induced inflammation by promoting TRAF6 degradation, suggesting that CA as the potential therapeutic candidate for the treatment of inflammation associated diseases.

Immunomodulatory Effects of Diterpenes and Their Derivatives Through NLRP3 Inflammasome Pathway: A Review

Nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing protein (NLRP) inflammasomes are involved in the molecular pathogenesis of many diseases and disorders. Among NLRPs, the NLRP3 (in humans encoded by the NLRP3 gene) is expressed predominantly in macrophages as a component of the inflammasome and is associated with many diseases, including gout, type 2 diabetes, multiple sclerosis, atherosclerosis, and neurological diseases and disorders. Diterpenes containing repeated isoprenoid units in their structure are a member of some essential oils that possess diverse biological activities and are becoming a landmark in the field of drug discovery and development. This review sketches a current scenario of diterpenes or their derivatives acting through NLRPs, especially NLRP3-associated pathways with anti-inflammatory effects. For this, a literature survey on the subject has been undertaken using a number of known databases with specific keywords. Findings from the aforementioned databases suggest that diterpenes and their derivatives can exert anti-inflammatory effects via NLRPs-related pathways. Andrographolide, triptolide, kaurenoic acid, carnosic acid, oridonin, teuvincenone F, and some derivatives of tanshinone IIA and phorbol have been found to act through NLRP3 inflammasome pathways. In conclusion, diterpenes and their derivatives could be one of the promising compounds for the treatment of NLRP3-mediated inflammatory diseases and disorders.

P22077 inhibits LPS-induced inflammatory response by promoting K48-linked ubiquitination and degradation of TRAF6

Inflammation is a biological process associated with multiple human disorders such as autoimmune diseases and metabolic diseases. Therefore, alleviation of inflammation is important for disease prevention or treatment. Recently, deubiquitinating enzymes (DUBs), especially ubiquitin specific protease-7 (USP7) attracts increasing attention as a potential drug target for inflammation. As an inhibitor of USP7, P22077 has been used to study the roles of USP7 in inflammatory response and neuroblastoma growth. However, the role and precise mechanism of P22077 in anti-inflammatory is still indistinct. In this study, we demonstrated that P22077 could attenuate the release of pro-inflammatory factors including TNF-α, IL-1β, IL-6 and NO, suppress mRNA expression of COX-2 and iNOS, and inhibit activation of NF-κB and MAPKs signaling pathways in Raw264.7 cells and mouse peritoneal macrophages after LPS stimulation. In vivo study showed that P22077 could relieve inflammatory response and reduce the lung injury in C57BL/6 mice with LPS-induced endotoxemia. Mechanically, P22077 might play an anti-inflammatory role by promoting tumor necrosis factor receptor-associated factor 6 (TRAF6) degradation via K48-linked polyubiquitination. These findings provide a rationale for the role of the P22077 in anti-inflammatory pathway and the promising clinical application of P22077 to treat inflammatory diseases.

Application quantitative proteomics approach to identify differentially expressed proteins associated with cardiac protection mediated by cycloastragenol in acute myocardial infarction rats

Acute myocardial infarction (AMI) is an acute heart disease. Cycloastragenol, as a natural product, inhibits inflammation and protects cardiomyocytes. Cycloastragenol (Y006) modulates inflammation in AMI is not known. To explore the function of Cycloastragenol in AMI, this study investigated the effect of Y006 and its mechanisms both in vitro and in vivo. Y006 influences the concentration of 11 proteins, as shown by a proteomics analysis, immunohistochemistry and western blotting. Among these 11 proteins, Erk1/2, PLCG1, IKBKG, and ZEB1 are related to inflammatory regulation. BAX, COX2, and GSK3β are involved in modulating cardiomyocyte apoptosis, and RhoA and DSC2 are directly associated with myocardial function. However, the functions of ARHGAP17 and Rit2 in heart are less well established. Additionally, Y006 suppressed TNF-α, IFN-γ and IL-17 production in PBMCs (peripheral blood monocytes) from patients with acute myocardial infarction and enhanced IL-10 and IL-4 expression. Similar results were obtained in a rat model of AMI by flow cytometry detection and ELISA. Our findings indicate that Y006 protects rats from AMI through direct or indirect inhibition of inflammation and cardiomyocyte apoptosis. However, the specific mechanism of Y006's protective function requires further study. Nonetheless, this research revealed a novel aspect for the treatment of myocardial infarction. SIGNIFICANCE: In the present study, we undertook the first proteomic evaluation of Cycloastragenol (Y006) function in acute myocardial infarction (AMI). Y006 significantly improved myocardial function in vivo by regulating multiple molecular expressions. Hypoxia is a direct reason for AMI. And our data support a role of Y006 in gene expression, cell apoptosis under hypoxia. The conclusions of this research assist to explain the potential molecular mechanism in Cycloastragenol treating AMI and supply a new method for ameliorating AMI.

Psoriasis-Like Inflammation Induced Renal Dysfunction through the TLR/NF-κB Signal Pathway

Pathological studies have shown an association between psoriasis and renal injury (RI), but the mechanism between RI and psoriasis was still unclear. This paper was designed to investigate the relationship and mechanism between psoriasis-like inflammation and renal injury in BALB/C mice. Mice were topically smeared imiquimod followed by various analyses in skin lesions, urine protein, kidney/serum inflammatory cytokines, kidney function, podocyte membrane proteins, and toll-like receptors/nuclear factor kappa-b (TLR/NF-κB) pathway-associated proteins. Meanwhile, lipopolysaccharide (LPS) and dexamethasone (DEX) were intraperitoneally injected to promote and inhibit inflammation accompanied by imiquimod to elaborate the relevance between inflammatory levels and RI. In the model group, the Psoriasis Area and Severity Index (PASI) scores of scaly and erythema obviously increased (p < 0.01), creatinine and blood urea nitrogen significantly increased (p < 0.01), the positive area of hematoxylin-eosin (HE) and periodic acid-Schiff (PAS) staining in kidney increased (p < 0.01), malondialdehyde significantly increased with superoxide dismutase (SOD) decreased (p < 0.01), 24-hour urine protein increased and the expressions of podocin and CD2 associate protein (CD2AP) decreased (p < 0.01), and kidney/serum inflammatory factors (IL-17, IL-1β, IL-6, TNF-α, and IL-22) and TLR/NF-κB-related expression (TLR2, TLR4, MyD88, and NF-κBp65) all increased (p < 0.01). The RI was aggravated with the TLR/NF-κB related expression being upregulated by LPS (p < 0.05). On the contrary, the RI was alleviated by DEX (p < 0.05). Our data showed that psoriasis-like inflammation damaged the renal function via the TLR/NF-κB signal pathway. Inhibiting TLR/NF-κB-related protein expression may be effective for the treatment of RI caused by psoriasis.

Tendril extract of Cucurbita moschata suppresses NLRP3 inflammasome activation in murine macrophages and human trophoblast cells

Inflammation is the root cause of many diseases that pose a serious threat to human health. Excessive inflammation can also result in preterm birth or miscarriage in pregnant women. Pumpkin (Cucurbita moschata Duchesne, CMD) is a well-known traditional health food and medicinal herb used in many countries to treat diabetes, obesity, osteoporosis, cancer and other diseases. In this study, we investigated the effects of hot water extract derived from the tendrils of C. moschata Duchesne (TCMD) on NLRP3 inflammasome activation in murine macrophages and human trophoblast cells. The TCMD treatment of LPS-primed bone marrow-derived macrophages (BMDMs) and human trophoblast cells attenuated NLRP3 inflammasome activation induced by inflammasome activators such as ATP, nigericin, and monosodium urate (MSU). TCMD treatment suppressed IL-1β secretion in a dose-dependent manner, without affecting IL-6 secretion. In addition, TCMD inhibited NLRP3-dependent pyroptosis in BMDMs. TCMD also suppressed the release of mature IL-1β and activation of cleaved-caspase-1 via limited ASC oligomerization. Furthermore, TCMD significantly inhibited IL-1β secretion and pyroptotic cell death in human trophoblast cells. These results suggest that TCMD exhibits anti-inflammatory effects mediated via inhibition of NLRP3 inflammasome activation suggesting therapeutic potential against inflammatory diseases, preterm birth, and miscarriage.

Cirsitakaoside isolated from Premna szemaoensis reduces LPS-induced inflammatory responses in vitro and in vivo

Cirsitakaoside is a natural compound isolated from Premna szemaoensis. However, the anti-inflammatory effects of cirsitakaoside are poorly understood. We investigated the anti-inflammatory action of cirsitakaoside in lipopolysaccharide (LPS)-stimulated macrophages and mice in vivo. Cirsitakaoside could suppress the production of pro-inflammatory cytokines such as interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in a dose-dependent manner in LPS-stimulated mouse peritoneal macrophages and RAW264.7 cells. Cirsitakaoside also could inhibit inducible nitric oxide synthase (iNOS) mRNA and cyclooxygenase-2 (COX-2) mRNA expression in LPS-stimulated mouse peritoneal macrophages and RAW264.7 cells. These effects were partially carried out by inactivated nuclear factor-κB (NF-κB) and Mitogen-activated protein kinases (MAPKs) pathway via inhibiting the phosphorylation of the IKKα/β, IκBα and c-Jun N-terminal kinase/stress-activated protein kinase (JNK) in LPS-stimulated murine macrophages. In vivo, we showed that cirsitakaoside could relieve LPS-induced inflammation response. These results suggest that cirsitakaoside has the potential anti-inflammatory effect for treatment of inflammation diseases.