The PRY/SPRY domain of pyrin/TRIM20 interacts with β2-microglobulin to promote inflammasome formation

Efficacy and safety of anakinra and canakinumab in PSTPIP1-associated inflammatory diseases: a comprehensive scoping review

Introduction

This scoping review explores the effectiveness of IL-1 pathway inhibitors in managing PSTPIP1-associated inflammatory diseases (PAID). These diseases are marked by abnormal IL-1 pathway activation due to genetic mutations.

Methods

Our methodology adhered to a pre-published protocol and involved a thorough search of MEDLINE and EMBASE databases up to February 2022, following the Joanna Briggs Institute Reviewer's Manual and the PRISMA Extension for Scoping Reviews. The review included studies reporting on IL-1 pathway inhibitor use in PAID patients.

Results

From an initial pool of 5,225 articles, 36 studies involving 43 patients were selected. The studies predominantly used observational designs and exhibited diversity in patient demographics, treatment approaches, and outcomes. Anakinra and canakinumab demonstrated promise in treating sterile pyogenic arthritis, pyoderma gangrenosum, and acne (PAPA) and PSTPIP1-associated myeloid-related-proteinemia inflammatory (PAMI) syndromes, with scant data on other syndromes. Notably, there was a paucity of information on the adverse effects of these treatments, necessitating cautious interpretation of their safety profile.

Conclusion

Current evidence on IL-1 pathway inhibitors for PAID is primarily from observational studies and remains limited. Rigorous research with larger patient cohorts is imperative for more definitive conclusions. Collaborative efforts among specialized research centers and international health initiatives are key to advancing this field.

The pyrin inflammasome, a leading actor in pediatric autoinflammatory diseases

The activation of the pyrin inflammasome represents a highly intriguing mechanism employed by the innate immune system to effectively counteract pathogenic agents. Despite its key role in innate immunity, pyrin has also garnered significant attention due to its association with a range of autoinflammatory diseases (AIDs) including familial Mediterranean fever caused by disruption of the MEFV gene, or in other genes involved in its complex regulation mechanisms. Pyrin activation is strictly dependent on homeostasis-altering molecular processes, mostly consisting of the disruption of the small Ras Homolog Family Member A (RhoA) GTPases by pathogen toxins. The downstream pathways are regulated by the phosphorylation of specific pyrin residues by the kinases PKN1/2 and the binding of the chaperone 14-3-3. Furthermore, a key role in pyrin activation is played by the cytoskeleton and gasdermin D, which is responsible for membrane pores in the context of pyroptosis. In addition, recent evidence has highlighted the role of steroid hormone catabolites and alarmins S100A8/A9 and S100A12 in pyrin-dependent inflammation. The aim of this article is to offer a comprehensive overview of the most recent evidence on the pyrin inflammasome and its molecular pathways to better understand the pathogenesis behind the significant group of pyrin-related AIDs.

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

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

Recent Insights in Pyrin Inflammasome Activation: Identifying Potential Novel Therapeutic Approaches in Pyrin-Associated Autoinflammatory Syndromes

Pyrin is a cytosolic protein encoded by the MEFV gene, predominantly expressed in innate immune cells. Upon activation, it forms an inflammasome, a multimolecular complex that enables the activation and secretion of IL-1β and IL-18. In addition, the Pyrin inflammasome activates Gasdermin D leading to pyroptosis, a highly pro-inflammatory cell death. Four autoinflammatory syndromes are associated with Pyrin inflammasome dysregulation: familial Mediterranean fever, hyper IgD syndrome/mevalonate kinase deficiency, pyrin-associated autoinflammation with neutrophilic dermatosis, and pyogenic arthritis, pyoderma gangrenosum, and acne syndrome. In this review, we discuss recent advances in understanding the molecular mechanisms regulating the two-step model of Pyrin inflammasome activation. Based on these insights, we discuss current pharmacological options and identify a series of existing molecules with therapeutic potential for the treatment of pyrin-associated autoinflammatory syndromes.

Evolution and expression of the duck TRIM gene repertoire

Tripartite motif (TRIM) proteins are involved in development, innate immunity, and viral restriction. TRIM gene repertoires vary between species, likely due to diversification caused by selective pressures from pathogens; however, this has not been explored in birds. We mined a de novo assembled transcriptome for the TRIM gene repertoire of the domestic mallard duck (Anas platyrhynchos), a reservoir host of influenza A viruses. We found 57 TRIM genes in the duck, which represent all 12 subfamilies based on their C-terminal domains. Members of the C-IV subfamily with C-terminal PRY-SPRY domains are known to augment immune responses in mammals. We compared C-IV TRIM proteins between reptiles, birds, and mammals and show that many C-IV subfamily members have arisen independently in these lineages. A comparison of the MHC-linked C-IV TRIM genes reveals expansions in birds and reptiles. The TRIM25 locus with related innate receptor modifiers is adjacent to the MHC in reptile and marsupial genomes, suggesting the ancestral organization. Within the avian lineage, both the MHC and TRIM25 loci have undergone significant TRIM gene reorganizations and divergence, both hallmarks of pathogen-driven selection. To assess the expression of TRIM genes, we aligned RNA-seq reads from duck tissues. C-IV TRIMs had high relative expression in immune relevant sites such as the lung, spleen, kidney, and intestine, and low expression in immune privileged sites such as in the brain or gonads. Gene loss and gain in the evolution of the TRIM repertoire in birds suggests candidate immune genes and potential targets of viral subversion.

Genotype-Phenotype Associations of Children With Familial Mediterranean Fever in a Cohort Consisting of M694V Mutation and Implications for Colchicine-Resistant Disease

OBJECTIVES

The aim of this study was to investigate the clinical associations of the second allele mutations and the effect of genotype and presenting features on colchicine resistance in children with familial Mediterranean fever (FMF), carrying at least one M694V variant.

METHODS

The medical records of the patients diagnosed with FMF, in whom at least one allele M694V mutation was detected, were reviewed. Patients were grouped according to the genotype as M694V homozygotes, compound heterozygote M694V with an exon 10 mutation, compound heterozygote M694V with a variant of unknown significance (VUS), and M694V heterozygotes. Disease severity was assessed with the International Severity Scoring System for FMF.

RESULTS

Among the 141 patients included, homozygote M694V (43.3%) was the most frequent MEFV genotype. Clinical manifestations of FMF at diagnosis were not significantly different according to genotypic alterations except homozygote M694V. Besides, homozygous M694V was associated with a more severe disease, with more frequent comorbidities and colchicine-resistant disease. A lower disease severity score was observed in compound heterozygotes with VUS than in M694V heterozygotes (median 1 vs 2, p = 0.006). Regression analysis revealed that homozygous M694V, arthritis, and frequency of attacks were associated with an increased risk of colchicine-resistant disease.

CONCLUSIONS

Clinical manifestations of FMF at diagnosis with a M694V allele were predominantly influenced by the M694V rather than the second allele mutations. Although homozygous M694V was associated with the most severe form, the presence of compound heterozygosity with a VUS did not affect disease severity or clinical features. Homozygous M694V confers the highest risk of colchicine-resistant disease.

Behçet disease, familial Mediterranean fever and MEFV variations: More than just an association

Behçet disease (BD) and familial Mediterranean fever (FMF) are two inflammatory disorders that share many features including historical background, ethnical distribution and inflammatory characteristics. Several studies suggested that BD and FMF might occur in the same individual more commonly than expected. Additionally, the pathogenic MEFV gene variants, especially p.Met694Val, activating the inflammasome complex have been shown to increase the risk for BD in regions where both FMF and BD are prevalent. Whether these variants are associated with certain disease subtypes and whether they may help in the planning of treatment need to be explored. This review provides a recent overview of the plausible association between FMF and BD and the role of MEFV variants in the pathogenesis of BD.

Genetic and Epigenetic Regulation of MEFV Gene and Their Impact on Clinical Outcome in Auto-Inflammatory Familial Mediterranean Fever Patients

Epigenetic modifications play a pivotal role in autoimmune/inflammatory disorders and could establish a bridge between personalized medicine and disease epidemiological contexts. We sought to investigate the role of epigenetic modifications beside genetic alterations in the MEFV gene in familial Mediterranean fever (FMF). The study comprised 63 FMF patients diagnosed according to the Tel Hashomer criteria: 37 (58.7%) colchicine-responders, 26 (41.3%) non-responders, and 19 matched healthy controls. MEFV mutations were detected using a CE/IVD-labeled 4-230 FMF strip assay. DNA methylation of MEFV gene exon 2 was measured using bisulfite modification and related to pyrin level, phenotypic picture, MEFV mutations, disease severity, serum amyloid A (SAA), CRP, ESR, disease severity, and colchicine response. Our results showed that FMF patients exhibited significantly higher methylation percentage (p < 0.001) and lower pyrin levels (p < 0.001) compared to the control. The MEFV gene M694I mutation was the most commonly reported mutation (p < 0.004). High methylation percentage of the MEFV exon 2 and low pyrin concentration were correlated with disease severity, high SAA, ESR levels, H-pylori, and renal calculi. In conclusion, this study highlights the relation between high methylation percentage, reduced pyrin level, and different biomarkers in FMF, which underscores their role in the pathogenesis of FMF and could be considered as potential therapeutic targets.

The Roles of Monocytes and Macrophages in Behçet’s Disease With Focus on M1 and M2 Polarization

Behçet’s disease (BD) is a systemic inflammatory disease characterized by recurrent oral ulcers, genital ulcers, cutaneous inflammation, and uveitis. In addition, other potentially life-threatening lesions may occur in the intestinal tract, blood vessels, and central nervous system. This heterogeneity of the BD phenotype hampers development of a targeted treatment strategy. The pathogenesis of BD is not fully elucidated, but it is likely that genetically susceptible people develop BD in response to environmental factors, such as microbiome factors. Genetic analyses have identified various BD susceptibility loci that function in HLA-antigen presentation pathways, Th1 and Th17 cells, and autoinflammation related to monocytes/macrophages, or that increase levels of pro-inflammatory cytokines, reduce levels of anti-inflammatory cytokines, or act in dysfunctional mucous barriers. Our functional analyses have revealed that impairment of M2 monocyte/macrophage-mediated anti-inflammatory function through IL-10 is crucial to BD pathogenesis. We, therefore, propose that BD is an M1-dominant disease. In this review, we describe the roles of monocytes and macrophages in BD and consider the potential of these cells as therapeutic targets.