A20 in inflammation and autoimmunity

The pathogenesis, clinical presentations and treatment of monogenic systemic vasculitis

Many monogenic autoinflammatory diseases, including DADA2 (deficiency of adenosine deaminase 2), HA20 (haploinsufficiency of A20), SAVI (STING-associated vasculopathy with onset in infancy), COPA syndrome, LAVLI (LYN kinase-associated vasculopathy and liver fibrosis) and VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome, present predominantly with vasculitis and constitute a substantial subgroup of vasculitic conditions associated with a 'probable aetiology'. The spectrum of monogenic vasculitis encompasses all sizes and types of blood vessel, ranging from large vessels to medium-size and small vessels, and from the arterial side to the venous side of the vasculature. Monogenic vasculitis typically starts early in life during infancy or childhood; VEXAS syndrome, which presents in late adulthood, is an exception. The activation of myeloid cells via inflammasome and nuclear factor-κB pathways, type I interferon-enhanced autoimmune mechanisms and/or dysregulated adaptive immune responses have an important role in the development of immune-mediated endothelial dysfunction and vascular damage. Genetic testing is essential for the diagnosis of underlying monogenic autoinflammatory diseases; however, the penetrance of genetic variants can vary. Increased awareness and recognition of distinctive clinical findings could facilitate earlier diagnosis and allow for more-targeted treatments.

Association of TNFAIP3 expression and gene polymorphisms with systemic lupus erythematosus susceptibility in the Chinese Han population

Systemic lupus erythematosus (SLE) is an autoimmune disease with complex underlying mechanisms that have not been fully elucidated. Tumor necrosis factor-α induces protein 3 (TNFAIP3) has been identified as an SLE susceptibility gene. This study aimed to investigate the association between TNFAIP3 levels in peripheral blood mononuclear cells (PBMCs), TNFAIP3 single nucleotide polymorphisms (SNPs), and SLE genetic susceptibility. The mRNA expression level of the TNFAIP3 and the concentration of A20 protein were significantly reduced and negatively correlated with disease activity in patients with active SLE. The C allele of rs377482653 was positively correlated with SLE susceptibility (T vs C: OR = 1.74, 95 %CI: 1.09-2.78, p = 0.02). There were no significant differences in the allele frequencies of rs582757 (p = 0.60), rs583522 (p = 0.40) and rs10499194 (p = 0.38) between SLE and healthy controls. Individuals with the rs377482653 C allele and CT genotype were more likely to develop arthritis (C: OR = 1.94, 95 %CI: 1.03-3.63, p = 0.04; CT: OR = 2.54, 95 %CI: 1.19-5.43, p = 0.02). Thus, we established that SLE shows a lower expression of TNFAIP3 and that rs377482653 polymorphism is associated with SLE.

Plant-derived extracts or compounds for Helicobacter-associated gastritis: a systematic review of their anti-Helicobacter activity and anti-inflammatory effect in animal experiments

BACKGROUND

Helicobacter infection, which is the leading cause of gastritis and stomach cancer, has become common worldwide. Almost all Helicobacter-infected patients have chronic active gastritis, also known as Helicobacter-associated gastritis (HAG). However, the eradication rate of Helicobacter is decreasing due to the poor efficacy of current medications, which causes infection to recur, inflammation to persist, and stomach cancer to develop. Natural components have robust antibacterial activity and anti-inflammatory capacity, as confirmed by many studies of alternative natural medicines.

PURPOSE

This article aimed to conduct a comprehensive search and meta-analysis to evaluate the efficacy of anti-Helicobacter and anti-inflammatory activities of plant-derived extracts or compounds that can treat HAG in animal experiments. We intended to provide detailed preclinical-research foundation including plant and compound information, as well as the mechanisms by which these plant-derived substances inhibit the progression of Helicobacter infection, gastritis and neoplasms for future study.

METHODS

The systematic review is aligned with the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, and the protocol was registered in PROSPERO (CRD42024527889). An extensive search was performed across multiple databases, including PubMed, Scopus, Web of Science, Embase, China National Knowledge Infrastructure (CNKI), the Chinese Scientific Journal database (VIP), the Wanfang database, and the China biomedical literature service system (SinoMed), up until November 2023. Meta-analysis on Review Manager software (RevMan 5.4) estimating anti-Helicobacter and anti-inflammatory activity was performed. We used the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) risk of bias tool to evaluate the risk of bias of each study included.

RESULTS

Our study encompassed 61 researches, comprised 36 extracts and 37 compounds improving HAG by inhibiting Helicobacter infection, the inflammatory response, oxidative stress, and regulating apoptosis and proliferation. Sixteen families especially Asteraceae, Fabaceae and Rosaceae and nine classes including Terpenoids, Alkaloids, Phenols, and Flavonoids may be promising directions for valuable new drugs. The Meta-analyse demonstrated the plant-base substance treatments possess significant anti-Helicobacter and anti-inflammation activity comparing to control groups. The included plants and compounds confirmed that signaling pathways NF-κB, JAK2/STAT3, MAPK, TLR4/MyD88, PI3K/AKT, NLRP3/Caspase-1 and NRF2/HO-1 play a key role in the progression of HAG.

CONCLUSION

Plant-derived extracts or compounds actively improve HAG by modulating relevant mechanisms and signaling pathways, particularly through the anti-Helicobacter and inflammatory regulation ways. Further researches to apply these treatments in humans are needed, which will provide direction for the future development of therapeutic drugs to increase eradication rate and alleviate gastritis.

The Role of A20 in Cancer: Friend or Foe?

A20 is a ubiquitin-editing enzyme that has emerged as a key regulator of inflammatory signaling with paradoxical roles in cancer. Acting as both an oncogene and a tumor suppressor gene depending on the cellular context, A20 modulates important cell pathways, such as NF-κB signaling and autophagy. In this review, we summarize the dual roles of A20 in tumorigenesis, highlighting its ability to promote tumor progression in cancers, such as breast and melanoma, while functioning as a tumor suppressor in lymphomas and hepatocellular carcinoma. We discuss the interplay of A20 with autophagy, a process that is important for maintaining cellular homeostasis and influencing tumor dynamics. By integrating recent findings, we provide insight into how dysregulation of A20 and its associated pathways can either suppress or drive cancer development, which may lead to improved therapeutic intervention.

YTHDF2 Regulates Advanced Glycation End Products-Induced Melanogenesis through Inhibiting A20 Expression in Human Dermal Fibroblasts

Fibroblast A20 suppresses advanced glycation end products (AGEs)-induced melanogenesis by inhibiting NLRP3 inflammasome activation. AGEs repress A20 expression and significantly m6A-methylate A20 mRNA in fibroblasts. YTHDF2 is the most studied m6A reader protein and can accelerate degradation of m6A-modified mRNA. Whether YTHDF2 regulates AGEs-induced A20 expression and pigmentation is unknown. In this study, we confirmed that YTHDF2 inversely regulated AGEs-BSA-inhibited A20 expression but facilitated AGEs-BSA-activated NF-κB signaling and NLRP3 inflammasome in fibroblasts via YTHDF2 knockdown and overexpression experiments. Mechanistically, YTHDF2 bound to m6A-modified A20 mRNA induced by AGEs-BSA and increased its degradation. Moreover, fibroblast YTHDF2 robustly promoted AGEs-BSA-induced IL-18 level in coculture supernatants and melanin content, tyrosinase activity, and expression of microphthalmia-associated transcription factor and tyrosinase in melanocytes, which were significantly blocked by IL-18 binding protein. Further, fibroblast YTHDF2 markedly increased AGEs-BSA-induced epidermal melanin level in cocultured ex vivo skin and MAPKs activation in melanocytes. Importantly, upregulated dermal YTHDF2 expression was negatively correlated with dermal A20 level and positively associated with both epidermal melanin and dermal AGEs content in sun-exposed skin and lesions of melasma and solar lentigo. These findings suggest that fibroblast YTHDF2 positively regulates AGEs-induced melanogenesis mainly via A20/ NF-κB /NLRP3 inflammasome/ IL-18 /MAPKs axis in an m6A-dependent manner and functions in photoaging-induced hyperpigmentation skin disorders.

[Monogenic autoinflammatory uveitis]

Monogenic autoinflammatory uveitis belongs to the spectrum of monogenic autoinflammatory diseases. When early-onset uveitis is associated with specific extra-ocular manifestations, particularly in a familial or geographical context, it guides the clinician towards a diagnosis of a monogenic autoinflammatory disease. The clinical presentation and mode of inheritance will help identify the underlying cause, and the detection of a pathogenic variant will confirm the diagnosis and guide the management approach. In this review, we outline the main monogenic autoinflammatory uveitis conditions that clinicians should be aware of: Blau syndrome, ROSAH syndrome, cryopyrin-associated periodic syndromes (CAPS), partial mevalonate kinase deficiency, A20 haploinsufficiency, and NEMO syndrome.

Ubiquitin Ligases in Control: Regulating NLRP3 Inflammasome Activation

Ubiquitin ligases play pivotal roles in the regulation of NLR family pyrin domain containing 3 (NLRP3) inflammasome activation, a critical process in innate immunity and inflammatory responses. This review explores the intricate mechanisms by which various E3 ubiquitin ligases exert both positive and negative influences on NLRP3 inflammasome activity through diverse post-translational modifications. Negative regulation of NLRP3 inflammasome assembly is mediated by several E3 ligases, including F-box and leucine-rich repeat protein 2 (FBXL2), tripartite motif-containing protein 31 (TRIM31), and Casitas B-lineage lymphoma b (Cbl-b), which induce K48-linked ubiquitination of NLRP3, targeting it for proteasomal degradation. Membrane-associated RING-CH 7 (MARCH7) similarly promotes K48-linked ubiquitination leading to autophagic degradation, while RING finger protein (RNF125) induces K63-linked ubiquitination to modulate NLRP3 function. Ariadne homolog 2 (ARIH2) targets the nucleotide-binding domain (NBD) domain of NLRP3, inhibiting its activation, and tripartite motif-containing protein (TRIM65) employs dual K48 and K63-linked ubiquitination to suppress inflammasome assembly. Conversely, Pellino2 exemplifies a positive regulator, promoting NLRP3 inflammasome activation through K63-linked ubiquitination. Additionally, ubiquitin ligases influence other components critical for inflammasome function. TNF receptor-associated factor 3 (TRAF3) mediates K63 polyubiquitination of apoptosis-associated speck-like protein containing a CARD (ASC), facilitating its degradation, while E3 ligases regulate caspase-1 activation and DEAH-box helicase 33 (DHX33)-NLRP3 complex formation through specific ubiquitination events. Beyond direct inflammasome regulation, ubiquitin ligases impact broader innate immune signaling pathways, modulating pattern-recognition receptor responses and dendritic cell maturation. Furthermore, they intricately control NOD1/NOD2 signaling through K63-linked polyubiquitination of receptor-interacting protein 2 (RIP2), crucial for nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) activation. Furthermore, we explore how various pathogens, including bacteria, viruses, and parasites, have evolved sophisticated strategies to hijack the host ubiquitination machinery, manipulating NLRP3 inflammasome activation to evade immune responses. This comprehensive analysis provides insights into the molecular mechanisms underlying inflammasome regulation and their implications for inflammatory diseases, offering potential avenues for therapeutic interventions targeting the NLRP3 inflammasome. In conclusion, ubiquitin ligases emerge as key regulators of NLRP3 inflammasome activation, exhibiting a complex array of functions that finely tune immune responses. Understanding these regulatory mechanisms not only sheds light on fundamental aspects of inflammation but also offers potential therapeutic avenues for inflammatory disorders and infectious diseases.

IL-33 released during challenge phase regulates allergic asthma in an age-dependent way

Epithelial-derived cytokines, especially type 2 alarmins (TSLP, IL-25, and IL-33), have emerged as critical mediators of type 2 inflammation. IL-33 attracts more interest for its strong association with allergic asthma, especially in childhood asthma. However, the age-dependent role of IL-33 to the development of allergic asthma remains elusive. Here, using OVA-induced allergic asthma model in neonatal and adult mice, we report that IL-33 is the most important alarmin in neonatal lung both at steady state or inflammation. The deficiency of IL-33/ST2 abrogated the development of allergic asthma only in neonates, whereas in adults the effect was limited. Interestingly, the deficiency of IL-33/ST2 equally dampened the ILC2 responses in both neonatal and adult models. However, the effect of IL-33/ST2 deficiency on Th2 responses is age-dependent, which is only blocked in neonates. Furthermore, IL-33/ST2 signaling is dispensable for OVA sensitization. Following OVA challenge in adults, the deficiency of IL-33/ST2 results in compensational more TSLP, which in turn recruits and activates lung DCs and boosts Th2 responses. The enriched γδ T17 cells in IL-33/ST2 deficient neonatal lung suppress the expression of type 2 alarmins, CCL20 and GM-CSF via IL-17A, thus might confer the inhibition of allergic asthma. Finally, on the basis of IL-33 deficiency, the additive protective effects of TSLP blocking is much more pronounced than IL-25 blocking in adults. Our studies demonstrate that the role of IL-33 for ILC2 and Th2 responses varies among ages in OVA models and indicate that the factor of age should be considered for intervention of asthma.

Astrocytes phenomics as new druggable targets in healthy aging and Alzheimer's disease progression

For over a century after their discovery astrocytes were regarded merely as cells located among other brain cells to hold and give support to neurons. Astrocytes activation, "astrocytosis" or A1 functional state, was considered a detrimental mechanism against neuronal survival. Recently, the scientific view on astrocytes has changed. Accumulating evidence indicate that astrocytes are not homogeneous, but rather encompass heterogeneous subpopulations of cells that differ from each other in terms of transcriptomics, molecular signature, function and response in physiological and pathological conditions. In this review, we report and discuss the recent literature on the phenomic differences of astrocytes in health and their modifications in disease conditions, focusing mainly on the hippocampus, a region involved in learning and memory encoding, in the age-related memory impairments, and in Alzheimer's disease (AD) dementia. The morphological and functional heterogeneity of astrocytes in different brain regions may be related to their different housekeeping functions. Astrocytes that express diverse transcriptomics and phenomics are present in strictly correlated brain regions and they are likely responsible for interactions essential for the formation of the specialized neural circuits that drive complex behaviors. In the contiguous and interconnected hippocampal areas CA1 and CA3, astrocytes show different, finely regulated, and region-specific heterogeneity. Heterogeneous astrocytes have specific activities in the healthy brain, and respond differently to physiological or pathological stimuli, such as inflammaging present in normal brain aging or beta-amyloid-dependent neuroinflammation typical of AD. To become reactive, astrocytes undergo transcriptional, functional, and morphological changes that transform them into cells with different properties and functions. Alterations of astrocytes affect the neurovascular unit, the blood-brain barrier and reverberate to other brain cell populations, favoring or dysregulating their activities. It will be of great interest to understand whether the differential phenomics of astrocytes in health and disease can explain the diverse vulnerability of the hippocampal areas to aging or to different damaging insults, in order to find new astrocyte-targeted therapies that might prevent or treat neurodegenerative disorders.

A20 as a Potential Therapeutic Target for COVID-19

BACKGROUND

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a major concern due to its astonishing prevalence and high fatality rate, especially among elderly people. Patients suffering from COVID-19 may exhibit immunosuppression in the initial stage of infection, while a cytokine storm can occur when the disease progresses to a severe stage. This inopportune immune rhythm not only makes patients more susceptible to the virus but also leads to numerous complications resulting from the excessive production of inflammatory factors. A20, which is widely accepted as a pivotal regulator of inflammation, has been shown to be implicated in the processes of antiviral responses and immunosuppression. Thus, A20 may participate in regulating the pathological processes of COVID-19.

METHODS

This narrative literature review summarizes recent evidence on the mechanisms of A20 in regulating the pathological processes of COVID-19. We also downloaded single-cell RNA-seq data sets from healthy individuals and patients with varying severities of COVID-19 from the NCBI GEO database to further dissect A20's regulatory mechanisms of these intricate cytokine pathways that are closely associated with SARS-CoV-2 infection.

RESULTS

A20 might be one of the most critical anti-infectious and anti-inflammatory factors involved in the pathogenesis of COVID-19. It effectively suppresses the immune damage and inflammatory storm caused by viral infection.

CONCLUSIONS

Understanding the relationship between A20-regulated signaling pathways and pathological processes of COVID-19 can provide insight into potential targets for intervention. Precise regulation of A20 to induce antiviral activity and an anti-inflammatory response could mediate the pathogenesis of COVID-19 and could become an effective treatment.

A20 intrinsically influences human effector T-cell survival and function by regulating both NF-κB and JNK signaling

A20 is a dual-function ubiquitin-editing enzyme that maintains immune homeostasis by restraining inflammation. Although A20 serves a similar negative feedback function for T-cell receptor (TCR) signaling, the molecular mechanisms utilized and their ultimate impact on human T-cell function remain unclear. TCR engagement triggers the assembly of the CARD11-BCL10-MALT1 (CBM) protein complex, a signaling platform that governs the activation of downstream transcription factors including NF-κB and c-Jun/AP-1. Utilizing WT and A20 knockout Jurkat T cells, we found that A20 is required to negatively regulate NF-κB and JNK. Utilizing a novel set of A20 mutants in NF-κB and AP-1-driven reporter systems, we discovered the ZnF7 domain is crucial for negative regulatory capacity, while deubiquitinase activity is dispensable. Successful inactivation of A20 in human primary effector T cells congruently conferred sustained NF-κB and JNK signaling, including enhanced upregulation of activation markers, and increased secretion of several cytokines including IL-9. Finally, loss of A20 in primary human T cells resulted in decreased sensitivity to restimulation-induced cell death and increased sensitivity to cytokine withdrawal-induced death. These findings demonstrate the importance of A20 in maintaining T-cell homeostasis via negative regulation of both NF-κB and JNK signaling.

Research progress on the nonstructural protein 1 (NS1) of influenza a virus

Influenza A virus (IAV) is the leading cause of highly contagious respiratory infections, which poses a serious threat to public health. The non-structural protein 1 (NS1) is encoded by segment 8 of IAV genome and is expressed in high levels in host cells upon IAV infection. It is the determinant of virulence and has multiple functions by targeting type Ι interferon (IFN-I) and type III interferon (IFN-III) production, disrupting cell apoptosis and autophagy in IAV-infected cells, and regulating the host fitness of influenza viruses. This review will summarize the current research on the NS1 including the structure and related biological functions of the NS1 as well as the interaction between the NS1 and host cells. It is hoped that this will provide some scientific basis for the prevention and control of the influenza virus.

Critical Analysis of Cytoplasmic Progression of Inflammatory Signaling Suggests Potential Pharmacologic Targets for Wound Healing and Fibrotic Disorders

Successful skin wound healing is dependent on an interplay between epidermal keratinocytes and dermal fibroblasts as they react to local extracellular factors (DAMPs, PAMPs, cytokines, etc.) surveyed from that environment by numerous membrane receptors (e.g., TLRs, cytokine receptors, etc.). In turn, those receptors are the start of a cytoplasmic signaling pathway where balance is key to effective healing and, as needed, cell and matrix regeneration. When directed through NF-κB, these signaling routes lead to transient responses to the benefit of initiating immune cell recruitment, cell replication, local chemokine and cytokine production, and matrix protein synthesis. The converse can also occur, where ongoing canonical NF-κB activation leads to chronic, hyper-responsive states. Here, we assess three key players, TAK1, TNFAIP3, and TNIP1, in cytoplasmic regulation of NF-κB activation, which, because of their distinctive and yet inter-related functions, either promote or limit that activation. Their balanced function is integral to successful wound healing, given their significant control over the expression of inflammation-, fibrosis-, and matrix remodeling-associated genes. Intriguingly, these three proteins have also been emphasized in dysregulated NF-κB signaling central to systemic sclerosis (SSc). Notably, diffuse SSc shares some tissue features similar to an excessive inflammatory/fibrotic wound response without eventual resolution. Taking a cue from certain instances of aberrant wound healing and SSc having some shared aspects, e.g., chronic inflammation and fibrosis, this review looks for the first time, to our knowledge, at what those pathologies might have in common regarding the cytoplasmic progression of NF-κB-mediated signaling. Additionally, while TAK1, TNFAIP3, and TNIP1 are often investigated and reported on individually, we propose them here as three proteins whose consequences of function are very highly interconnected at the signaling focus of NF-κB. We thus highlight the emerging promise for the eventual clinical benefit derived from an improved understanding of these integral signal progression modulators. Depending on the protein, its indirect or direct pharmacological regulation has been reported. Current findings support further intensive studies of these points in NF-κB regulation both for their basic function in healthy cells as well as with the goal of targeting them for translational benefit in multiple cutaneous wound healing situations, whether stemming from acute injury or a dysregulated inflammatory/fibrotic response.

Constitutive expression of the deubiquitinating enzyme CYLD does not affect microglia phenotype or function in homeostasis and neuroinflammation

The deubiquitinating enzyme CYLD negatively regulates NF-κB signaling by removing activating ubiquitin chains from several members of the NF-κB pathway. Thereby, CYLD is critical for the maintenance and differentiation of various immune cells. Despite the importance of the NF-κB pathway in microglia regulation, the role of CYLD in microglia has not been investigated so far. In this study, we investigated whether CYLD in microglia can protect against neuroinflammation using a newly generated conditional mouse strain (Rosa26-Cyld-tdTomato) that allows cell type-specific CYLD overexpression. Here, we show that overexpression of CYLD in microglia did not alter microglia numbers or microglia morphology in different brain regions. Additionally, CYLD overexpression did not modify the microglial response to LPS-induced neuroinflammation or the disease severity in experimental autoimmune encephalomyelitis (EAE). Finally, also immune cell infiltration into the CNS during EAE and under steady state conditions remained unaffected by microglial CYLD overexpression. Our findings suggest that CYLD overexpression does not alter microglial function, and thus does not represent a viable therapeutic strategy in neuroinflammatory conditions. This study highlights the complexity of ubiquitin-mediated signaling in neuroinflammation and the need for cell-type-specific investigations. The Rosa26-Cyld-tdTomato mouse model offers a valuable tool for studying CYLD's role across various tissues and cell types. KEY MESSAGES: Novel mouse strain for cell type-specific overexpression of the deubiquitinating enzyme CYLD. CYLD overexpression in microglia did not alter microglia numbers or morphology in the steady state. CYLD overexpression in microglia did not protect mice from LPS-induced neuroinflammation or EAE. CYLD overexpression in microglia did not influence their gene expression during neuroinflammation.

Farm-dust mediated protection of childhood asthma: Mass cytometry reveals novel cellular regulation

BACKGROUND

Farm-dust mediated asthma protection in childhood was replicated in numerous epidemiological studies. Central immune mechanisms are not fully understood. This exploratory study aimed to disentangle underlying immunological regulation of farm-dust mediated protection in peripheral blood on a single-cell level.

METHODS

Single-cell protein expression of in vitro farm-dust stimulated and unstimulated cells from allergic asthmatics and healthy controls were measured using mass cytometry. Analysis of innate and adaptive cellular proportions (linear regression) and T-cell proliferation was performed. Functional marker intensity was investigated using Earth Mover's Distance and the Monte Carlo permutation test.

RESULTS

Farm-dust stimulation induced cell type-specific regulation: Key-features of farm-dust stimulation comprised opposing regulation of immune-cell frequencies (downregulated innate cell populations (monocytes/DCs (p < .001), NK-cells (p < .05)) and upregulated adaptive populations (B-cells, CD4+ T-cells (both p < .05)), reduced CD4+ CD25- T-cell proliferation, and differential cell type-specific functional marker expression. Following stimulation, functional marker analysis revealed induced activation (CD25) in T-cells and NK-T-cells in both phenotypes even after correction for multiple testing. Cytotoxicity (GZMB) and inflammation (pERK1/2, pp38) related markers were reduced in T-cells exclusively in asthmatic children. Asthma-associated markers (Gata3, RORγ, and HLA-DR) were reduced in T- and innate- cell populations of asthmatics following stimulation. B-cells displayed a phenotypically independent increase of diverse functional markers upon farm-dust stimulation.

CONCLUSIONS

This study mimicking in vivo environmental exposure identified a novel profile of immune-regulatory markers using mass cytometry demonstrating decreased asthma-associated markers following farm-dust stimulation. These findings may be key for further studies on asthma prevention in childhood.

Understanding the Dynamics of Human Defensin Antimicrobial Peptides: Pathogen Resistance and Commensal Induction

Antimicrobial peptides (AMPs), also known as host defense peptides, are petite molecules with inherent microbicidal properties that are synthesized by the host's innate immune response. These peptides serve as an initial barrier against pathogenic microorganisms, effectively eliminating them. Human defensin (HD) AMPs represent a prominent group of peptides involved in the innate immune response of humans. These peptides are primarily produced by neutrophils and epithelial cells, serving as a crucial defense mechanism against invading pathogens. The extensive research conducted has focused on the broad spectrum of antimicrobial activities and multifaceted immunomodulatory functions exhibited by human defensin AMPs. During the process of co-evolution between hosts and bacterial pathogens, bacteria have developed the ability to recognize and develop an adaptive response to AMPs to counterattack their bactericidal activity by different antibiotic-resistant mechanisms. However, numerous non-pathogenic commensal bacteria elicit the upregulation of defensins as a means to surmount the resistance mechanisms implemented by pathogens. The precise mechanism underlying the induction of HD by commensal organisms remains to be fully understood. This review summarizes the most recent research on the expression of human defensin by pathogens and discusses the various defense mechanisms used by pathogens to counter host AMP production. We also mention recent developments in the commensal induction of defensin AMPs. A better knowledge of the pathogens' defensin AMP resistance mechanisms and commensals' induction of AMP expression may shed light on the creation of fresh antibacterial tactics to get rid of bacterial infection.

TAX1BP1/A20 inhibited TLR2-NF-κB activation to induce tolerant expression of IL-6 in endothelial cells

The inflammatory cascadedriven by interleukin-6 (IL-6) plays a crucial role in the initiation and progression of chronic inflammatory conditions such as atherosclerosis. Research has demonstrated that prolonged exposure to inflammatory stimuli leads to the development of "immune tolerance" in specialized immune cells such as monocytes and macrophages, serving as a mechanism to prevent tissue damage and curb the inflammatory cascade. However, our recent investigation revealed that immune tolerance did not effectively regulate the production of IL-6 in human umbilical vein endothelial cells (HUVECs) when stimulated by a Toll-like receptor 2 (TLR2) ligand Pam3CSK4, which is a potent activator of the pro-inflammatory transcription factor NF-κB. Furthermore, the negative regulator of NF-κB signaling, A20, was ineffective in suppressing TLR2-induced IL-6 synthesis in this context. Notably, all A20 auxiliary molecules, with the exception of TAX1BP1, were found to be significantly expressed in HUVECs. DNA methylation in TAX1BP1 was confirmed in GEO database. According to the information provided, it is hypothesized that altered DNA methylation in HUVECs could potentially lead to decreased expression of TAX1BP1, thereby impeding A20's capacity to modulate continuous activation of the TLR2-NF-κB pathway. This may consequently lead to unregulated production of IL-6, evading immune tolerance mechanisms. Subsequent investigations suggested that demethylating TAX1BP1 could enhance its expression, potentially reducing the endogenous IL-6 levels induced by repeated TLR2 stimulation and restoring A20's inhibitory role in NF-κB signaling. Additionally, over-expression of TAX1BP1 coulddecrease the production of atherosclerosis-associated cytokines like IL-6, MCP-1, ICAM-1, and VCAM-1, while increasing NO release following repeated Pam3cks4 stimulation, along with enhanced co-localization of TAX1BP1 and A20. These findings indicate that inducing immune tolerance in endothelial cells may effectively suppress endogenous IL-6 production and halt the IL-6-mediated inflammatory cascade, with TAX1BP1/A20 identified as crucial components in this process.These insights provide novel perspectives and potential targets for therapeutic strategies in inflammatoryimmunological disorders involving the overproduction of IL-6.

Dietary Zn proteinate with moderate chelation strength alleviates heat stress-induced intestinal barrier function damage by promoting expression of tight junction proteins via the A20/NF-κB p65/MMP-2 pathway in the jejunum of broilers

BACKGROUND

The aim of this study was to determine whether and how Zn proteinate with moderate chelation strength (Zn-Prot M) can alleviate heat stress (HS)-induced intestinal barrier function damage of broilers. A completely randomized design was used for comparatively testing the effects of Zn proteinate on HS and non-HS broilers. Under high temperature (HT), a 1 (Control, HT-CON) + 2 (Zn source) × 2 (added Zn level) factorial arrangement of treatments was used. The 2 added Zn sources were Zn-Prot M and Zn sulfate (ZnS), and the 2 added Zn levels were 30 and 60 mg/kg. Under normal temperature (NT), a CON group (NT-CON) and pair-fed group (NT-PF) were included.

RESULTS

The results showed that HS significantly reduced mRNA and protein expression levels of claudin-1, occludin, junctional adhesion molecule-A (JAMA), zonula occludens-1 (ZO-1) and zinc finger protein A20 (A20) in the jejunum, and HS also remarkably increased serum fluorescein isothiocyanate dextran (FITC-D), endotoxin and interleukin (IL)-1β contents, serum diamine oxidase (DAO) and matrix metalloproteinase (MMP)-2 activities, nuclear factor kappa-B (NF-κB) p65 mRNA expression level, and protein expression levels of NF-κB p65 and MMP-2 in the jejunum. However, dietary supplementation with Zn, especially organic Zn as Zn-Prot M at 60 mg/kg, significantly decreased serum FITC-D, endotoxin and IL-1β contents, serum DAO and MMP-2 activities, NF-κB p65 mRNA expression level, and protein expression levels of NF-κB p65 and MMP-2 in the jejunum of HS broilers, and notably promoted mRNA and protein expression levels of claudin-1, ZO-1 and A20.

CONCLUSIONS

Our results suggest that dietary Zn, especially 60 mg Zn/kg as Zn-Prot M, can alleviate HS-induced intestinal barrier function damage by promoting the expression of TJ proteins possibly via induction of A20-mediated suppression of the NF-κB p65/MMP-2 pathway in the jejunum of HS broilers.

Somatic mutations in tumor-infiltrating lymphocytes impact on antitumor immunity

Immune checkpoint inhibitors (ICIs) exert clinical efficacy against various types of cancers by reinvigorating exhausted CD8+ T cells that can expand and directly attack cancer cells (cancer-specific T cells) among tumor-infiltrating lymphocytes (TILs). Although some reports have identified somatic mutations in TILs, their effect on antitumor immunity remains unclear. In this study, we successfully established 18 cancer-specific T cell clones, which have an exhaustion phenotype, from the TILs of four patients with melanoma. We conducted whole-genome sequencing for these T cell clones and identified various somatic mutations in them with high clonality. Among the somatic mutations, an SH2D2A loss-of-function frameshift mutation and TNFAIP3 deletion could activate T cell effector functions in vitro. Furthermore, we generated CD8+ T cell-specific Tnfaip3 knockout mice and showed that Tnfaip3 function loss in CD8+ T cell increased antitumor immunity, leading to remarkable response to PD-1 blockade in vivo. In addition, we analyzed bulk CD3+ T cells from TILs in additional 12 patients and identified an SH2D2A mutation in one patient through amplicon sequencing. These findings suggest that somatic mutations in TILs can affect antitumor immunity and suggest unique biomarkers and therapeutic targets.

Genetic Mutations Associated With TNFAIP3 (A20) Haploinsufficiency and Their Impact on Inflammatory Diseases

TNF-α-induced protein 3 (TNFAIP3), commonly referred to as A20, is an integral part of the ubiquitin-editing complex that significantly influences immune regulation, apoptosis, and the initiation of diverse immune responses. The A20 protein is characterized by an N-terminal ovarian tumor (OTU) domain and a series of seven zinc finger (ZNF) domains. Mutations in the TNFAIP3 gene are implicated in various immune-related diseases, such as Behçet's disease, polyarticular juvenile idiopathic arthritis, autoimmune thyroiditis, autoimmune hepatitis, and rheumatoid arthritis. These mutations can lead to a spectrum of symptoms, including, but not limited to, recurrent fever, ulcers, rashes, musculoskeletal and gastrointestinal dysfunctions, cardiovascular issues, and respiratory infections. The majority of these mutations are either nonsense (STOP codon) or frameshift mutations, which are typically associated with immune dysfunctions. Nonetheless, missense mutations have also been identified as contributors to these conditions. These genetic alterations may interfere with several biological pathways, notably abnormal NF-κB signaling and dysregulated ubiquitination. Currently, there is no definitive treatment for A20 haploinsufficiency; however, therapeutic strategies can alleviate the symptoms in patients. This review delves into the mutations reported in the TNFAIP3 gene, the clinical progression in affected individuals, potential disease mechanisms, and a brief overview of the available pharmacological interventions for A20 haploinsufficiency. Mandatory genetic testing of the TNFAIP3 gene should be performed in patients diagnosed with autoinflammatory disorders to better understand the genetic underpinnings and guide treatment decisions.

Ubiquitin: Not just a one-way ticket to the proteasome, but a therapeutic dial to fine-tune the molecular landscape of disease

Recently, there is a rise in studies that recognize the importance of targeting ubiquitin and related molecular machinery in various therapeutic contexts. Here we briefly discuss the history of ubiquitin, its biological roles in protein degradation and beyond, as well as the current state of ubiquitin-targeting therapeutics across diseases. We conclude that targeting ubiquitin machinery is approaching a renaissance, and tapping its full potential will require embracing a wholistic perspective of ubiquitin's multifaceted roles.

Sequential immunotherapy: towards cures for autoimmunity

Despite major progress in the treatment of autoimmune diseases in the past two decades, most therapies do not cure disease and can be associated with increased risk of infection through broad suppression of the immune system. However, advances in understanding the causes of autoimmune disease and clinical data from novel therapeutic modalities such as chimeric antigen receptor T cell therapies provide evidence that it may be possible to re-establish immune homeostasis and, potentially, prolong remission or even cure autoimmune diseases. Here, we propose a 'sequential immunotherapy' framework for immune system modulation to help achieve this ambitious goal. This framework encompasses three steps: controlling inflammation; resetting the immune system through elimination of pathogenic immune memory cells; and promoting and maintaining immune homeostasis via immune regulatory agents and tissue repair. We discuss existing drugs and those in development for each of the three steps. We also highlight the importance of causal human biology in identifying and prioritizing novel immunotherapeutic strategies as well as informing their application in specific patient subsets, enabling precision medicine approaches that have the potential to transform clinical care.

[A20 haploinsufficiency: what do clinicians need to know?]

A20 Haploinsufficiency (HA20) is a monogenic autoinflammatory disease associated with an autosomal dominant mutation in the TNFAIP3 gene. It induces a defect in the inactivation of the pro-inflammatory NF-κB pathway. Less than 200 cases have been described worldwide. The clinical picture of the disease is essentially based on the association of recurrent fever and/or biologic inflammatory syndrome, aphtosis, often bipolar, and cutaneous folliculitis. However, the clinical spectrum of HA20 is very broad, including gastrointestinal (mainly colonic ulceration), articular, cutaneous, pericardial and lymph node involvement, as well as frequent association with organ-specific or non-specific autoimmune manifestations and/or autoantibodies, including antinuclear antibodies and anti-dsDNA. As a result, the diagnosis of a number of systemic or organic disorders, most notably Behçet's disease, Crohn's disease, and sometimes even systemic lupus, has been corrected to HA20 by molecular research for a heterozygous mutation with functional deficiency of TNFAIP3. Although the first signs of the disease often appear in the first years of life, the diagnosis is often made in adulthood and requires the involvement of both paediatric and adult physicians. Treatment for HA20 is not codified and relies on conventional or biological immunomodulators and immunosuppressants adapted to the patient's symptomatology. This review highlights the enormous diagnostic challenges in this autoinflammatory disease.

Inhibition of NLRP3 inflammasome activation by A20 through modulation of NEK7

The NLRP3 inflammasome, a pivotal component of innate immunity, has been implicated in various inflammatory disorders. The ubiquitin-editing enzyme A20 is well known to regulate inflammation and maintain homeostasis. However, the precise molecular mechanisms by which A20 modulates the NLRP3 inflammasome remain poorly understood. Here, our study revealed that macrophages deficient in A20 exhibit increased protein abundance and elevated mRNA level of NIMA-related kinase 7 (NEK7). Importantly, A20 directly binds with NEK7, mediating its K48-linked ubiquitination, thereby targeting NEK7 for proteasomal degradation. Our results demonstrate that A20 enhances the ubiquitination of NEK7 at K189 and K293 ubiquitinated sites, with K189 playing a crucial role in the binding of NEK7 to A20, albeit not significantly influencing the interaction between NEK7 and NLRP3. Furthermore, A20 disrupts the association of NEK7 with the NLRP3 complex, potentially through the OTU domain and/or synergistic effect of ZnF4 and ZnF7 motifs. Significantly, NEK7 deletion markedly attenuates the activation of the NLRP3 inflammasome in A20-deficient conditions, both in vitro and in vivo. This study uncovers a mechanism by which A20 inhibits the NLRP3 inflammasome.

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.

A20 Haploinsufficiency: A Systematic Review of 177 Cases

A20 haploinsufficiency is an autoinflammatory disease caused by defective inactivation of the NF-κB pathway. We conducted a systematic literature review of articles reporting patients with TNFAIP3 sequence variants from 2016 to August 2023 following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Data from 177 patients from 65 articles were retrieved (108 women). The principal features were mucosal ulcers (n = 129); fever (n = 93) followed by gastrointestinal (n = 81); skin features (n = 76); autoimmunity (n = 61), including thyroiditis (n = 25) and lupus (n = 16); and joint involvements (n = 54). Five patients had died at the time of publication. In 54 of 63 patients, CRP was significantly elevated during flares, with a median of 51 mg/l. The most commonly used treatment included corticosteroids and nonsteroidal anti-inflammatory drugs (n = 32), TNF blockers (n = 29), colchicine (n = 28), and methotrexate (n = 14). TNFAIP3 variants impacted the ovarian tumor domain in 92 cases and a Zinc finger domain in 68 cases. Geographic origin, reported sex, and variant type significantly impacted phenotype. A better understanding of the wide A20 haploinsufficiency phenotype could facilitate the diagnosis process. Much remains to be elucidated about pathogenesis and treatment to improve outcome in patients with A20 haploinsufficiency.

Re-exploration of immunotherapy targeting EMT of hepatocellular carcinoma: Starting from the NF-κB pathway

Hepatocellular carcinoma (HCC) is the fifth most common malignancies worldwide, and its high morbidity and mortality have brought a heavy burden to the global public health system. Due to the concealment of its onset, the limitation of treatment, the acquisition of multi-drug resistance and radiation resistance, the treatment of HCC cannot achieve satisfactory results. Epithelial mesenchymal transformation (EMT) is a key process that induces progression, distant metastasis, and therapeutic resistance to a variety of malignant tumors, including HCC. Therefore, targeting EMT has become a promising tumor immunotherapy method for HCC. The NF-κB pathway is a key regulatory pathway for EMT. Targeting this pathway has shown potential to inhibit HCC infiltration, invasion, distant metastasis, and therapeutic resistance. At present, there are still some controversies about this pathway and new ideas of combined therapy, which need to be further explored. This article reviews the progress of immunotherapy in improving EMT development in HCC cells by exploring the mechanism of regulating EMT.

The deubiquitinase Otud7b suppresses cone photoreceptor degeneration in mouse models of retinal degenerative diseases

Primary and secondary cone photoreceptor death in retinal degenerative diseases, including age-related macular degeneration (AMD) and retinitis pigmentosa (RP), leads to severe visual impairment and blindness. Although the cone photoreceptor protection in retinal degenerative diseases is crucial for maintaining vision, the underlying molecular mechanisms are unclear. Here, we found that the deubiquitinase Otud7b/Cezanne is predominantly expressed in photoreceptor cells in the retina. We analyzed Otud7b-/- mice, which were subjected to light-induced damage, a dry AMD model, or were mated with an RP mouse model, and observed increased cone photoreceptor degeneration. Using RNA-sequencing and bioinformatics analysis followed by a luciferase reporter assay, we found that Otud7b downregulates NF-κB activity. Furthermore, inhibition of NF-κB attenuated cone photoreceptor degeneration in the light-exposed Otud7b-/- retina and stress-induced neuronal cell death resulting from Otud7b deficiency. Together, our findings suggest that Otud7b protects cone photoreceptors in retinal degenerative diseases by modulating NF-κB activity.

LPS-Induced Acute Lung Injury: Analysis of the Development and Suppression by the TNF-α-Targeting Aptamer

Acute lung injury (ALI) is a specific form of lung inflammation characterized by diffuse alveolar damage, noncardiogenic pulmonary edema, as well as a pulmonary and systemic inflammation. The pathogenesis of ALI involves a cascade inflammatory response accompanied by an increase in the local and systemic levels of proinflammatory cytokines and chemokines. The development of molecular tools targeting key components of cytokine signaling appears to be a promising approach in ALI treatment. The development of lipopolysaccharide (LPS)-induced ALI, as well as the feasibility of suppressing it by an aptamer targeting the proinflammatory cytokine TNF-α, was studied in a mouse model. The TNF-α level was shown to increase significantly and remain steadily high during the development of ALI. LPS-induced morphological signs of inflammation in the respiratory system become most pronounced 24 h after induction. Intranasal administration of TNF-α-targeting aptamers conjugated with polyethylene glycol (PEG-aptTNF-α) to mice with ALI reduced the intensity of inflammatory changes in lung tissue. Assessment of the levels of potential TNF-α target genes (Usp18, Traf1, and Tnfaip3) showed that their expression levels in the lungs increase during ALI development, while declining after the application of PEG-aptTNF-α. Therefore, topical use of TNF-α- targeting aptamers may be an efficient tool for treating ALI and other inflammatory lung diseases.

RIPK1 inhibitors: A key to unlocking the potential of necroptosis in drug development

Within the field of medical science, there is a great deal of interest in investigating cell death pathways in the hopes of discovering new drugs. Over the past two decades, pharmacological research has focused on necroptosis, a cell death process that has just been discovered. Receptor-interacting protein kinase 1 (RIPK1), an essential regulator in the cell death receptor signalling pathway, has been shown to be involved in the regulation of important events, including necrosis, inflammation, and apoptosis. Therefore, researching necroptosis inhibitors offers novel ways to treat a variety of disorders that are not well-treated by the therapeutic medications now on the market. The research and medicinal potential of RIPK1 inhibitors, a promising class of drugs, are thoroughly examined in this study. The journey from the discovery of Necrostatin-1 (Nec-1) to the recent advancements in RIPK1 inhibitors is marked by significant progress, highlighting the integration of traditional medicinal chemistry approaches with modern technologies like high-throughput screening and DNA-encoded library technology. This review presents a thorough exploration of the development and therapeutic potential of RIPK1 inhibitors, a promising class of compounds. Simultaneously, this review highlights the complex roles of RIPK1 in various pathological conditions and discusses potential inhibitors discovered through diverse pathways, emphasizing their efficacy against multiple disease models, providing significant guidance for the expansion of knowledge about RIPK1 and its inhibitors to develop more selective, potent, and safe therapeutic agents.

A Pilot Study to Develop Paraneoplastic Cerebellar Degeneration Mouse Model

Modeling paraneoplastic neurological diseases to understand the immune mechanisms leading to neuronal death is a major challenge given the rarity and terminal access of patients' autopsies. Here, we present a pilot study aiming at modeling paraneoplastic cerebellar degeneration with Yo autoantibodies (Yo-PCD). Female mice were implanted with an ovarian carcinoma cell line expressing CDR2 and CDR2L, the known antigens recognized by anti-Yo antibodies. To boost the immune response, we also immunized the mice by injecting antigens with diverse adjuvants and immune checkpoint inhibitors. Ataxia and gait instability were assessed in treated mice as well as autoantibody levels, Purkinje cell density, and immune infiltration in the cerebellum. We observed the production of anti-Yo antibodies in the CSF and serum of all immunized mice. Brain immunoreaction varied depending on the site of implantation of the tumor, with subcutaneous administration leading to a massive infiltration of immune cells in the meningeal spaces, choroid plexus, and cerebellar parenchyma. However, we did not observe massive Purkinje cell death nor any motor impairments in any of the experimental groups. Self-sustained neuro-inflammation might require a longer time to build up in our model. Unusual tumor antigen presentation and/or intrinsic, species-specific factors required for pro-inflammatory engagement in the brain may also constitute strong limitations to achieve massive recruitment of antigen-specific T-cells and killing of antigen-expressing neurons in this mouse model.

Commonly disrupted pathways in brain and kidney in a pig model of systemic endotoxemia

Sepsis is a life-threatening state that arises due to a hyperactive inflammatory response stimulated by infection and rarely other insults (e.g., non-infections tissue injury). Although changes in several proinflammatory cytokines and signals are documented in humans and small animal models, far less is known about responses within affected tissues of large animal models. We sought to understand the changes that occur during the initial stages of inflammation by administering intravenous lipopolysaccharide (LPS) to Yorkshire pigs and assessing transcriptomic alterations in the brain, kidney, and whole blood. Robust transcriptional alterations were found in the brain, with upregulated responses enriched in inflammatory pathways and downregulated responses enriched in tight junction and blood vessel functions. Comparison of the inflammatory response in the pig brain to a similar mouse model demonstrated some overlapping changes but also numerous differences, including oppositely dysregulated genes between species. Substantial changes also occurred in the kidneys following LPS with several enriched upregulated pathways (cytokines, lipids, unfolded protein response, etc.) and downregulated gene sets (tube morphogenesis, glomerulus development, GTPase signal transduction, etc.). We also found significant dysregulation of genes in whole blood that fell into several gene ontology categories (cytokines, cell cycle, neutrophil degranulation, etc.). We observed a strong correlation between the brain and kidney responses, with significantly shared upregulated pathways (cytokine signaling, cell death, VEGFA pathways) and downregulated pathways (vasculature and RAC1 GTPases). In summary, we have identified a core set of shared genes and pathways in a pig model of systemic inflammation.

A20 ameliorates advanced glycation end products-induced melanogenesis by inhibiting NLRP3 inflammasome activation in human dermal fibroblasts

BACKGROUND

Advanced glycation end products (AGEs) promote melanogenesis through activating NLRP3 inflammasome in fibroblasts. Although A20 has been highlighted to inhibit NLRP3 inflammasome activation, its roles and mechanisms remain elusive in photoaging-associated pigmentation.

OBJECTIVES

To determine the significance of fibroblast A20 in AGEs-induced NLRP3 inflammasome activation and pigmentation.

METHODS

The correlation between A20 and AGEs or melanin was studied in sun-exposed skin and lesions of melasma and solar lentigo. We then investigated A20 level in AGEs-treated fibroblast and the effect of fibroblast A20 overexpression or knockdown on AGEs-BSA-induced NLRP3 inflammasome activation and pigmentation, respectively. Finally, the severity of NLRP3 inflammasome activation and pigmentation was evaluated after mice were injected intradermally with A20-overexpression adeno-associated virus and AGEs-BSA.

RESULTS

Dermal A20 expression was decreased and exhibited negative correlation with either dermal AGEs deposition or epidermal melanin level in sun-exposed skin and pigmentary lesions. Moreover, both AGEs-BSA and AGEs-collagen robustly decreased A20 expression via binding to RAGE in fibroblasts. Further, A20 overexpression or depletion significantly decreased or augmented AGEs-BSA-induced activation of NF-κB pathway and NLRP3 inflammasome and IL-18 production and secretion in fibroblasts, respectively. Importantly, fibroblast A20 potently repressed AGEs-BSA-stimulated melanin content，tyrosinase activity，and expression of microphthalmia-associated transcription factor and tyrosinase in melanocytes. Particularly, fibroblast A20 significantly abrogated AGEs-BSA-promoted melanogenesis in ex vivo skin and mouse models. Additionally, fibroblast A20 inhibited AGEs-BSA-activated MAPKs in melanocytes and the epidermis of ex vivo skin.

CONCLUSIONS

Fibroblast A20 suppresses AGEs-stimulate melanogenesis in photoaging-associated hyperpigmentation disorders by inhibiting NLRP3 inflammasome activation.

The Anti-Oxidative, Anti-Inflammatory, Anti-Apoptotic, and Anti-Necroptotic Role of Zinc in COVID-19 and Sepsis

Zinc is a structural component of proteins, functions as a catalytic co-factor in DNA synthesis and transcription of hundreds of enzymes, and has a regulatory role in protein-DNA interactions of zinc-finger proteins. For many years, zinc has been acknowledged for its anti-oxidative and anti-inflammatory functions. Furthermore, zinc is a potent inhibitor of caspases-3, -7, and -8, modulating the caspase-controlled apoptosis and necroptosis. In recent years, the immunomodulatory role of zinc in sepsis and COVID-19 has been investigated. Both sepsis and COVID-19 are related to various regulated cell death (RCD) pathways, including apoptosis and necroptosis. Lack of zinc may have a negative effect on many immune functions, such as oxidative burst, cytokine production, chemotaxis, degranulation, phagocytosis, and RCD. While plasma zinc concentrations decline swiftly during both sepsis and COVID-19, this reduction is primarily attributed to a redistribution process associated with the inflammatory response. In this response, hepatic metallothionein production increases in reaction to cytokine release, which is linked to inflammation, and this protein effectively captures and stores zinc in the liver. Multiple regulatory mechanisms come into play, influencing the uptake of zinc, the binding of zinc to blood albumin and red blood cells, as well as the buffering and modulation of cytosolic zinc levels. Decreased zinc levels are associated with increasing severity of organ dysfunction, prolonged hospital stay and increased mortality in septic and COVID-19 patients. Results of recent studies focusing on these topics are summarized and discussed in this narrative review. Existing evidence currently does not support pharmacological zinc supplementation in patients with sepsis or COVID-19. Complementation and repletion should follow current guidelines for micronutrients in critically ill patients. Further research investigating the pharmacological mechanism of zinc in programmed cell death caused by invasive infections and its therapeutic potential in sepsis and COVID-19 could be worthwhile.

Comprehensive analysis of necroptosis-related genes in renal ischemia-reperfusion injury

Background

Oxidative stress is the primary cause of ischemia-reperfusion injury (IRI) in kidney transplantation, leading to delayed graft function (DGF) and implications on patient health. Necroptosis is believed to play a role in renal IRI. This research presents a comprehensive analysis of necroptosis-related genes and their functional implications in the context of IRI in renal transplantation.

Methods

The necroptosis-related differentially expressed genes (NR-DEGs) were identified using gene expression data from pre- and post-reperfusion renal biopsies, and consensus clustering analysis was performed to distinguish necroptosis-related clusters. A predictive model for DGF was developed based on the NR-DEGs and patients were divided into high- and low-risk groups. We investigated the differences in functional enrichment and immune infiltration between different clusters and risk groups and further validated them in single-cell RNA-sequencing (scRNA-seq) data. Finally, we verified the expression changes of NR-DEGs in an IRI mouse model.

Results

Five NR-DEGs were identified and were involved in various biological processes. The renal samples were further stratified into two necroptosis-related clusters (C1 and C2) showing different occurrences of DGF. The predictive model had a reliable performance in identifying patients at higher risk of DGF with the area under the curve as 0.798. Additionally, immune infiltration analysis indicated more abundant proinflammatory cells in the high-risk group, which was also found in C2 cluster with more DGF patients. Validation of NR-DEG in scRNA-seq data further supported their involvement in immune cells. Lastly, the mouse model validated the up-regulation of NR-DEGs after IR and indicated the correlations with kidney function markers.

Conclusions

Our research provides valuable insights into the identification and functional characterization of NR-DEGs in the context of renal transplantation and sheds light on their involvement in immune responses and the progression of IRI and DGF.

Alismol Purified from the Tuber of Alisma orientale Relieves Acute Lung Injury in Mice via Nrf2 Activation

Since the ethanol extract of Alisma orientale Juzepzuk (EEAO) suppresses lung inflammation by suppressing Nuclear Factor-kappa B (NF-κB) and activating Nuclear Factor Erythroid 2-related Factor 2 (Nrf2), we set out to identify chemicals constituting EEAO that suppress lung inflammation. Here, we provide evidence that among the five most abundant chemical constituents identified by Ultra Performance Liquid Chromatography (UPLC) and Nuclear Magnetic Resonance (NMR), alismol is one of the candidate constituents that suppresses lung inflammation in a lipopolysaccharide (LPS)-induced acute lung injury (ALI) mouse model and protects mice from ALI-like symptoms. Alismol did not induce cytotoxicity or reactive oxygen species (ROS). When administered to the lung of LPS-induced ALI mice (n = 5/group), alismol decreased the level of neutrophils and of the pro-inflammatory molecules, including Tumor Necrosis Factor-alpha (TNF-α), Interleukin-1 beta (IL-1β), Interleukin-6 (IL-6), Monocyte Chemoattractant Protein-1 (MCP-1), Interferon-gamma (IFN-γ), and Cyclooxygenase-2 (COX-2), suggesting an anti-inflammatory activity of alismol. Consistent with these findings, alismol ameliorated the key features of the inflamed lung of ALI, such as high cellularity due to infiltrated inflammatory cells, the development of hyaline membrane structure, and capillary destruction. Unlike EEAO, alismol did not suppress NF-κB activity but rather activated Nrf2. Consequently, alismol induced the expression of prototypic genes regulated by Nrf2, including Heme Oxygenase-1 (HO-1), NAD(P)H: quinine oxidoreductase-1 (NQO-1), and glutamyl cysteine ligase catalytic units (GCLC). Alismol activating Nrf2 appears to be associated with a decrease in the ubiquitination of Nrf2, a key suppressive mechanism for Nrf2 activity. Together, our results suggest that alismol is a chemical constituent of EEAO that contributes at least in part to suppressing some of the key features of ALI by activating Nrf2.

Association between PYTPN22 rs2476601, VEGF rs833070, TNFAIP3 rs6920220 Polymorphisms and Risk for Rheumatoid Arthritis in Early Undifferentiated Arthritis Patients: A Pilot Study

Background and Objectives: About 40% of early undifferentiated arthritis (UA) progresses to rheumatoid (RA) or other chronic arthritis. Novel diagnostic tools predicting the risk for this progression are needed to identify the patients who would benefit from early aggressive treatment. Evidence on the role of single-nucleotide polymorphisms (SNPs) in the development of RA has emerged. The aim of our study was to investigate the association between rs2476601, rs833070, and rs6920220 SNPs and UA progression to RA. Materials and Methods: Ninety-two UA patients were observed for 12 months. At study entry, demographic and clinical characteristics were recorded, musculoskeletal ultrasonography was performed, and blood samples were drawn to investigate levels of inflammatory markers, rheumatoid factor (RF), anti-citrullinated protein antibodies (anti-CCP)detect SNPs. After 12 months, UA outcomes were assessed, and patients were divided into two (RA and non-RA) groups. The association between the risk of progression to chronic inflammatory arthritis and analyzed SNPs was measured by computing odds ratios (OR). Results: After a 12-month follow-up, 27 (29.3%) patients developed RA, and 65 (70.7%) patients were assigned to the non-RA group. The arthritis of 21 patients (22.8%) from the non-RA group resolved completely, while the other 44 (47.2%) patients were diagnosed with another rheumatic inflammatory disease. The patients who developed RA had a significantly greater number of tender and swollen joints (p = 0.010 and p = 0.021 respectively) and were more frequently RF or anti-CCP (p < 0.001), and both RF and anti-CCP positive (p < 0.001) at the baseline as compared with the patients in the non-RA group. No significant association between rs2476601 (OR = 0.99, p = 0.98), rs833070 (OR = 1.0, p = 0.97), and rs6920220 (OR = 0.48, p = 0.13) polymorphisms and the risk of developing RA were found. Conclusions: No association between analyzed SNPs and a greater risk to progress from UA to RA was confirmed, although patients with rs6920220 AA + AG genotypes had fewer tender joints at the disease onset.

Sterile triggers drive joint inflammation in TNF- and IL-1β-dependent mouse arthritis models

Arthritis is the most common extra-intestinal complication in inflammatory bowel disease (IBD). Conversely, arthritis patients are at risk for developing IBD and often display subclinical gut inflammation. These observations suggest a shared disease etiology, commonly termed "the gut-joint-axis." The clinical association between gut and joint inflammation is further supported by the success of common therapeutic strategies and microbiota dysbiosis in both conditions. Most data, however, support a correlative relationship between gut and joint inflammation, while causative evidence is lacking. Using two independent transgenic mouse arthritis models, either TNF- or IL-1β dependent, we demonstrate that arthritis develops independently of the microbiota and intestinal inflammation, since both lines develop full-blown articular inflammation under germ-free conditions. In contrast, TNF-driven gut inflammation is fully rescued in germ-free conditions, indicating that the microbiota is driving TNF-induced gut inflammation. Together, our study demonstrates that although common inflammatory pathways may drive both gut and joint inflammation, the molecular triggers initiating such pathways are distinct in these tissues.

DUBing Primary Tumors of the Central Nervous System: Regulatory Roles of Deubiquitinases

The ubiquitin proteasome system (UPS) utilizes an orchestrated enzymatic cascade of E1, E2, and E3 ligases to add single or multiple ubiquitin-like molecules as post-translational modification (PTM) to proteins. Ubiquitination can alter protein functions and/or mark ubiquitinated proteins for proteasomal degradation but deubiquitinases (DUBs) can reverse protein ubiquitination. While the importance of DUBs as regulatory factors in the UPS is undisputed, many questions remain on DUB selectivity for protein targeting, their mechanism of action, and the impact of DUBs on the regulation of diverse biological processes. Furthermore, little is known about the expression and role of DUBs in tumors of the human central nervous system (CNS). In this comprehensive review, we have used publicly available transcriptional datasets to determine the gene expression profiles of 99 deubiquitinases (DUBs) from five major DUB families in seven primary pediatric and adult CNS tumor entities. Our analysis identified selected DUBs as potential new functional players and biomarkers with prognostic value in specific subtypes of primary CNS tumors. Collectively, our analysis highlights an emerging role for DUBs in regulating CNS tumor cell biology and offers a rationale for future therapeutic targeting of DUBs in CNS tumors.

What General Neurologists Should Know about Autoinflammatory Syndromes?

Autoinflammatory disorders encompass a wide range of conditions with systemic and neurological symptoms, which can be acquired or inherited. These diseases are characterized by an abnormal response of the innate immune system, leading to an excessive inflammatory reaction. On the other hand, autoimmune diseases result from dysregulation of the adaptive immune response. Disease flares are characterized by systemic inflammation affecting the skin, muscles, joints, serosa, and eyes, accompanied by unexplained fever and elevated acute phase reactants. Autoinflammatory syndromes can present with various neurological manifestations, such as aseptic meningitis, meningoencephalitis, sensorineural hearing loss, and others. Early recognition of these manifestations by general neurologists can have a significant impact on the prognosis of patients. Timely and targeted therapy can prevent long-term disability by reducing chronic inflammation. This review provides an overview of recently reported neuroinflammatory phenotypes, with a specific focus on genetic factors, clinical manifestations, and treatment options. General neurologists should have a good understanding of these important diseases.

Type-2 CD8+ T-cell formation relies on interleukin-33 and is linked to asthma exacerbations

CD4+ T helper 2 (Th2) cells and group 2 innate lymphoid cells are considered the main producers of type-2 cytokines that fuel chronic airway inflammation in allergic asthma. However, CD8+ cytotoxic T (Tc) cells - critical for anti-viral defense - can also produce type-2 cytokines (referred to as 'Tc2' cells). The role of Tc cells in asthma and virus-induced disease exacerbations remains poorly understood, including which micro-environmental signals and cell types promote Tc2 cell formation. Here we show increased circulating Tc2 cell abundance in severe asthma patients, reaching peak levels during exacerbations and likely emerging from canonical IFNγ+ Tc cells through plasticity. Tc2 cell abundance is associated with increased disease burden, higher exacerbations rates and steroid insensitivity. Mouse models of asthma recapitulate the human disease by showing extensive type-2 skewing of lung Tc cells, which is controlled by conventional type-1 dendritic cells and IFNγ. Importantly, we demonstrate that the alarmin interleukin-33 (IL-33) critically promotes type-2 cytokine production by lung Tc cells in experimental allergic airway inflammation. Our data identify Tc cells as major producers of type-2 cytokines in severe asthma and during exacerbations that are remarkably sensitive to alterations in their inflammatory tissue micro-environment, with IL-33 emerging as an important regulator of Tc2 formation.

A Model of iPSC-Derived Macrophages with TNFAIP3 Overexpression Reveals the Peculiarities of TNFAIP3 Protein Expression and Function in Human Macrophages

Macrophages play a crucial role in the development and control of inflammation. Understanding the mechanisms balancing macrophage inflammatory activity is important to develop new strategies for treating inflammation-related diseases. TNF-α-induced protein 3 (TNFAIP3, A20) is a negative regulator of intracellular inflammatory cascades; its deficiency induces hyper-inflammatory reactions. Whether A20 overexpression can dampen macrophage inflammatory response remains unclear. Here, we generated human-induced pluripotent stem cells with tetracycline-inducible A20 expression and differentiated them into macrophages (A20-iMacs). A20-iMacs displayed morphology, phenotype, and phagocytic activity typical of macrophages, and they displayed upregulated A20 expression in response to doxycycline. A20 overexpression dampened the A20-iMac response to TNF-α, as shown by a decreased expression of IL1B and IL6 mRNA. A dynamic analysis of A20 expression following the generation of A20-iMacs and control iMacs showed that the expression declined in iMacs and that iMacs expressed a lower molecular weight form of the A20 protein (~70 kDa) compared with less differentiated cells (~90 kDa). A low-level expression of A20 and the predominance of a low-molecular-weight A20 form were also characteristic of monocyte-derived macrophages. The study for the first time developed a model for generating macrophages with an inducible expression of a target gene and identified the peculiarities of A20 expression in macrophages that likely underlie macrophage preparedness for inflammatory reactivity. It also suggested the possibility of mitigating inflammatory macrophage responses via A20 overexpression.

The Role of Genetic Risk Factors in Pathogenesis of Childhood-Onset Systemic Lupus Erythematosus

The pathogenesis of childhood-onset systemic lupus erythematosus (cSLE) is complex and not fully understood. It involves three key factors: genetic risk factors, epigenetic mechanisms, and environmental triggers. Genetic factors play a significant role in the development of the disease, particularly in younger individuals. While cSLE has traditionally been considered a polygenic disease, it is now recognized that in rare cases, a single gene mutation can lead to the disease. Although these cases are uncommon, they provide valuable insights into the disease mechanism, enhance our understanding of pathogenesis and immune tolerance, and facilitate the development of targeted treatment strategies. This review aims to provide a comprehensive overview of both monogenic and polygenic SLE, emphasizing the implications of specific genes in disease pathogenesis. By conducting a thorough analysis of the genetic factors involved in SLE, we can improve our understanding of the underlying mechanisms of the disease. Furthermore, this knowledge may contribute to the identification of effective biomarkers and the selection of appropriate therapies for individuals with SLE.

Gene expression profiling of monocytes in recent-onset schizophrenia

Immune-related mechanisms have been suggested to be involved in schizophrenia. Various studies have shown changes in monocytes isolated from the blood of schizophrenia patients, including changes in monocyte numbers, as well as altered protein and transcript levels of important markers. However, validation of these findings and understanding how these results are related to immune-related changes in the brain and schizophrenia genetic risk factors, is limited. The goal of this study was to better understand changes observed in monocytes of patients with early-onset schizophrenia. Using RNA sequencing, we analyzed gene expression profiles of monocytes isolated from twenty patients with early-onset schizophrenia and seventeen healthy controls. We validated expression changes of 7 out of 29 genes that were differentially expressed in previous studies including TNFAIP3, DUSP2, and IL6. At a transcriptome-wide level, we found 99 differentially expressed genes. Effect sizes of differentially expressed genes were moderately correlated with differential expression in brain tissue (Pearson's r = 0.49). Upregulated genes were enriched for genes in NF-κB and LPS signaling pathways. Downregulated genes were enriched for glucocorticoid response pathways. These pathways have been implicated in schizophrenia before and play a role in regulating the activation of myeloid cells. Interestingly, they are also involved in several non-inflammatory processes in the central nervous system, such as neurogenesis and neurotransmission. Future studies are needed to better understand how dysregulation of the NF-κB and glucocorticoid pathways affects inflammatory and non-inflammatory processes in schizophrenia. The fact that dysregulation of these pathways is also seen in brain tissue, provides potential possibilities for biomarker development.

Endothelial PTP4A1 mitigates vascular inflammation via USF1/A20 axis-mediated NF-κB inactivation

AIMS

The nuclear factor-κB (NF-κB) signalling pathway plays a critical role in the pathogenesis of multiple vascular diseases. However, in endothelial cells (ECs), the molecular mechanisms responsible for the negative regulation of the NF-κB pathway are poorly understood. In this study, we investigated a novel role for protein tyrosine phosphatase type IVA1 (PTP4A1) in NF-κB signalling in ECs.

METHODS AND RESULTS

In human tissues, human umbilical artery ECs, and mouse models for loss of function and gain of function of PTP4A1, we conducted histological analysis, immunostaining, laser-captured microdissection assay, lentiviral infection, small interfering RNA transfection, quantitative real-time PCR and reverse transcription-PCR, as well as luciferase reporter gene and chromatin immunoprecipitation assays. Short hairpin RNA-mediated knockdown of PTP4A1 and overexpression of PTP4A1 in ECs indicated that PTP4A1 is critical for inhibiting the expression of cell adhesion molecules (CAMs). PTP4A1 increased the transcriptional activity of upstream stimulatory factor 1 (USF1) by dephosphorylating its S309 residue and subsequently inducing the transcription of tumour necrosis factor-alpha-induced protein 3 (TNFAIP3/A20) and the inhibition of NF-κB activity. Studies on Ptp4a1 knockout or transgenic mice demonstrated that PTP4A1 potently regulates the interleukin 1β-induced expression of CAMs in vivo. In addition, we verified that PTP4A1 deficiency in apolipoprotein E knockout mice exacerbated high-fat high-cholesterol diet-induced atherogenesis with upregulated expression of CAMs.

CONCLUSION

Our data indicate that PTP4A1 is a novel negative regulator of vascular inflammation by inducing USF1/A20 axis-mediated NF-κB inactivation. Therefore, the expression and/or activation of PTP4A1 in ECs might be useful for the treatment of vascular inflammatory diseases.

A20 interacts with mTORC2 to inhibit the mTORC2/Akt/Rac1 signaling axis in hepatocellular carcinoma cells

A20 acts as a tumor suppressor in hepatocellular carcinoma, especially inhibiting metastasis of the malignant cells. However, the mechanisms whereby A20 plays the inhibitory roles are not understood completely. Rac1 signaling is essential for cell migration in hepatocellular carcinoma metastasis. Nevertheless, it is not known whether and how A20 inhibits Rac1 signaling to suppress the migration of hepatocellular carcinoma cell. Thereby, we analyzed the relationship between A20 and Rac1 activation, as well as the activity of Akt and mTORC2, two signaling components upstream of Rac1, using gain and loss of function experiments. We found that the overexpression of A20 repressed, while the knockdown or knockout of A20 promoted, the activation of Rac1, Akt and mTORC2 in hepatocellular carcinoma cells. Moreover, the inhibitory effect of A20 on the mTORC2/Akt/Rac1 signaling axis was due to the interaction between A20 and mTORC2 complex. The binding of A20 to mTORC2 was mediated by the ZnF7 domain of A20 and M1 ubiquitin chain in the mTORC2 complex. Furthermore, A20 inhibited metastasis of hepatocellular carcinoma cells via restraining mTORC2 in a hepatocellular carcinoma xenograft mouse model. These findings revealed the relationship between A20 and mTORC2, and explained the molecular mechanisms of A20 in inhibition of hepatocellular carcinoma metastasis.

A novel circular RNA circNLRP3 alleviated ricin toxin-induced TNF-α production through sponging miR-221-5p

Acting as microRNA (miRNA) sponges, circular RNAs (circRNAs) have been discovered to be critical modulators of inflammatory processes. Ricin Toxin (RT) is highly toxic to mammalian cells and low doses of RT can induce acute inflammation. However, current researches on the underlying mechanism and function of circRNA/miRNA network in RT-induced inflammation are limited. Previously, we found miR-221-5p was aberrant and associated with the inflammation of RT induction. In this study, based on the circRNA high-throughput sequencing (circRNA-seq), we obtained a novel circRNA termed circNLRP3 and revealed that circNLRP3 can sponge miR-221-5p, release its target mRNA A20, and further suppress NF-κB signaling pathway to alleviated RT-induced TNF-α production. Our findings elucidated a possible mechanistic link between the circNLRP3/miR-221-5p/A20 axis and RT-induced inflammatory response, which may broaden our understanding of RT poisoning.

A20 and the noncanonical NF-κB pathway are key regulators of neutrophil recruitment during fetal ontogeny

Newborns are at high risk of developing neonatal sepsis, particularly if born prematurely. This has been linked to divergent requirements the immune system has to fulfill during intrauterine compared with extrauterine life. By transcriptomic analysis of fetal and adult neutrophils, we shed new light on the molecular mechanisms of neutrophil maturation and functional adaption during fetal ontogeny. We identified an accumulation of differentially regulated genes within the noncanonical NF-κB signaling pathway accompanied by constitutive nuclear localization of RelB and increased surface expression of TNF receptor type II in fetal neutrophils, as well as elevated levels of lymphotoxin α in fetal serum. Furthermore, we found strong upregulation of the negative inflammatory regulator A20 (Tnfaip3) in fetal neutrophils, which was accompanied by pronounced downregulation of the canonical NF-κB pathway. Functionally, overexpressing A20 in Hoxb8 cells led to reduced adhesion of these neutrophil-like cells in a flow chamber system. Conversely, mice with a neutrophil-specific A20 deletion displayed increased inflammation in vivo. Taken together, we have uncovered constitutive activation of the noncanonical NF-κB pathway with concomitant upregulation of A20 in fetal neutrophils. This offers perfect adaption of neutrophil function during intrauterine fetal life but also restricts appropriate immune responses particularly in prematurely born infants.

Decoding the genetic and epigenetic basis of asthma

Asthma is a complex and heterogeneous chronic inflammatory disease of the airways. Alongside environmental factors, asthma susceptibility is strongly influenced by genetics. Given its high prevalence and our incomplete understanding of the mechanisms underlying disease susceptibility, asthma is frequently studied in genome-wide association studies (GWAS), which have identified thousands of genetic variants associated with asthma development. Virtually all these genetic variants reside in non-coding genomic regions, which has obscured the functional impact of asthma-associated variants and their translation into disease-relevant mechanisms. Recent advances in genomics technology and epigenetics now offer methods to link genetic variants to gene regulatory elements embedded within non-coding regions, which have started to unravel the molecular mechanisms underlying the complex (epi)genetics of asthma. Here, we provide an integrated overview of (epi)genetic variants associated with asthma, focusing on efforts to link these disease associations to biological insight into asthma pathophysiology using state-of-the-art genomics methodology. Finally, we provide a perspective as to how decoding the genetic and epigenetic basis of asthma has the potential to transform clinical management of asthma and to predict the risk of asthma development.

A20 as a Potential New Tool in Predicting Recurrence and Patient's Survival in Oral Squamous Cell Carcinoma

A20, known as a potent inhibitor of NF-κB signaling, has been characterized in numerous clinical as well as preclinical studies. Recently, especially in various malignant diseases, the prognostic and therapeutic relevance of A20 was investigated. In oral squamous cell carcinoma (OSCC) however, the characterization of A20 is uncharted territory. We analyzed a tissue microarray (TMA) of 229 surgically-treated OSCC patients (2003-2013). Immunohistochemical (IHC) stainings were performed for A20 and CD3; additionally, standard haematoxylin-eosin staining was applied. IHC findings were correlated with a comprehensive dataset, comprising clinical and pathohistological information. A20 expression was analyzed in tumor cells as well as in tumor infiltrating lymphocytes (TILs) and correlated with the overall survival (OS) and recurrence-free survival (RFS) using uni- and multivariable Cox regression. The median follow-up time was 10.9 years and the A20 expression was significantly decreased in CD3+ TILs compared to mucosa-infiltrating lymphocytes (MILs). In the Kaplan-Meier analyses, higher A20 expression in TILs was correlated with better OS (p = 0.017) and RFS (p = 0.020). In the multivariable survival analysis, A20 overexpression correlated with improved OS (HR: 0.582; 95% CI 0.388-0.873, p = 0.009) and RFS (HR 0.605; 95% CI 0.411-0.889, p = 0.011). Our results indicate a novel prognostic role for A20 in OSCC. Due to its elevated expression in TILs, further research is highly desirable, which therefore could offer new therapeutic opportunities for patients suffering from OSCC.