Novel NLRP3/cryopyrin mutations and pro-inflammatory cytokine profiles in Behçet's syndrome patients

Targeting inflammasomes and pyroptosis in retinal diseases-molecular mechanisms and future perspectives

Retinal diseases encompass various conditions associated with sight-threatening immune responses and are leading causes of blindness worldwide. These diseases include age-related macular degeneration, diabetic retinopathy, glaucoma and uveitis. Emerging evidence underscores the vital role of the innate immune response in retinal diseases, beyond the previously emphasized T-cell-driven processes of the adaptive immune system. In particular, pyroptosis, a newly discovered programmed cell death process involving inflammasome formation, has been implicated in the loss of membrane integrity and the release of inflammatory cytokines. Several disease-relevant animal models have provided evidence that the formation of inflammasomes and the induction of pyroptosis in innate immune cells contribute to inflammation in various retinal diseases. In this review article, we summarize current knowledge about the innate immune system and pyroptosis in retinal diseases. We also provide insights into translational targeting approaches, including novel drugs countering pyroptosis, to improve the diagnosis and treatment of retinal diseases.

IL-38 in Behçet's disease: Gene expression in bronchoalveolar lavage from patients having pulmonary involvement

The etiological complexity of Behçet disease (BD), an immune-mediated rare form of vasculitis characterized by multi-organ involvement, is still elusive due to an incomplete understanding of the synergy between genetic susceptibility, environmental triggers, and an abnormal immune response. The diagnosis of BD relies on clinical symptoms. Lung inflammatory disorders are severe conditions of patients with BD, here we focus on the expression of biomarkers in BD patients with pulmonary manifestations. Aiming to identify additional discriminating biomarker patterns, we measured and compared protein and gene expression of IL-38 and a broad panel of selected genes in bronchoalveolar cells of patients suffering from BD with and without pulmonary involvement compared to controls. ELISA and RT-PCR analysis were applied. The first principal analysis highlighted decreased IL-38 level in BD patients compared to Rheumatoid Arthritis (RA) patients and controls: BD patients expressed lower IL-38 levels, particularly in cases with pulmonary involvement. The area under the curve (AUC) of the receiver-operating characteristic curve showed that IL-38 may be an eventual biomarker for BD. Co-cultured recombinant IL-38 and stimulated memory PBMCs of active BD, were able to suppress IL-17 and NLRP3 inflammasome and ameliorate the secretion of IL-10 and TGFβ. Transcription factors of the IL-1 family (IL-1β, IL-18, IL-32, IL-33 and IL-37) along with IFN-γ, IL-17, RORγt, Foxp3, TGFβ, IL-10 and NLRP3 inflammasome were the parameters that are the main contributor to the segregation between BD with and without lung involvement. Our results indicate that IL-38 might be involved in the pathogenesis of BD and the combined gene expression in BAL suggests distinct mechanisms governing the inflammatory disorders in the lung.

Vasculitis and the NLRP3 inflammasome

PURPOSE OF REVIEW

Vasculitis are a group of heterogeneous conditions characterized by chronic inflammation of blood vessels, leading to tissue destruction and organ failure. Vasculitis is an inflammatory process in which immune effector cells infiltrate blood vessels and surrounding tissues. The involvement of inflammasomes seems to occur during inflammatory processes.

RECENT FINDINGS

Studies have emphasized that genetic susceptibility is an important aspect of the pathogenesis of vasculitis. The innate immune system is a major contributor to these inflammatory diseases, suggesting that the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome plays a key role. NLRP3 activation causes the assembly of a large multiprotein and leads to the secretion of bioactive interleukin (IL)-1β and IL-18 as well as the induction of inflammatory cell death, termed pyroptosis. Accumulating evidence confirms the involvement of this cascade in sterile inflammatory diseases and other vascular diseases.

SUMMARY

In this review, we will summarize the current state of knowledge regarding the role of NLRP3 inflammasome in vascular diseases, and discuss the potential of the NLRP3 inflammasome as a therapeutic target.

Secretion of mitochondrial DNA via exosomes promotes inflammation in Behçet's syndrome

Mitochondrial DNA (mtDNA) leakage into the cytoplasm can occur when cells are exposed to noxious stimuli. Specific sensors recognize cytoplasmic mtDNA to promote cytokine production. Cytoplasmic mtDNA can also be secreted extracellularly, leading to sterile inflammation. However, the mode of secretion of mtDNA out of cells upon noxious stimuli and its relevance to human disease remain unclear. Here, we show that pyroptotic cells secrete mtDNA encapsulated within exosomes. Activation of caspase-1 leads to mtDNA leakage from the mitochondria into the cytoplasm via gasdermin-D. Caspase-1 also induces intraluminal membrane vesicle formation, allowing for cellular mtDNA to be taken up and secreted as exosomes. Encapsulation of mtDNA within exosomes promotes a strong inflammatory response that is ameliorated upon exosome biosynthesis inhibition in vivo. We further show that monocytes derived from patients with Behçet's syndrome (BS), a chronic systemic inflammatory disorder, show enhanced caspase-1 activation, leading to exosome-mediated mtDNA secretion and similar inflammation pathology as seen in BS patients. Collectively, our findings support that mtDNA-containing exosomes promote inflammation, providing new insights into the propagation and exacerbation of inflammation in human inflammatory diseases.

The inflammasome pathway: A key player in ocular surface and anterior segment diseases

Inflammasomes are multicomplex molecular regulators with an emerging importance in regulating ocular surface and anterior segment health and disease. Key components found in the eye include NF-κB, NLRP3, NLRC4, NLRP6, ASC, IL-1β, IL-18, and caspase-1. The role of NLRP1, NLRC4, AIM2, and NLRP3 inflammasomes in the pathogenesis of infectious ulcers, DED, uveitis, glaucoma, corneal edema, and other diseases is being studied with many developments. Attenuation of these diseases has been explored by blocking various molecules along the inflammasome pathway with agents like NAC, polydatin, calcitriol, glyburide, YVAD, and disulfiram. We provide a background on the inflammasome pathway as it relates to the ocular surface and anterior segment of the eye, discuss the role of inflammasomes in the above diseases in animals and humans, investigate new therapeutic targets, and explore the efficacy of new anti-inflammasome therapies.

NLRP3 gene variants and serum NLRP3 levels in periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome

OBJECTIVES

Although most of the autoinfammatory disorders have a confirmed genetic cause, periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome still has an unknown genetic background. However, familial cases of PFAPA syndrome have been reported suggesting a genetic its basis. PFAPA syndrome may also be considered an infammasome disorder as variants in infammasome-associated genes such as CARD8, NLRP3, and MEFV have been reported to contribute to the disease.

METHODS

Polymerase chain reaction (PCR)/Sanger sequencing analysis was performed for the detection of the variations in 71 PFAPA patients and 71 healthy controls. NLRP3 concentrations in serum were measured in 71 PFAPA patients and 71 healthy controls.

RESULTS

No statistically significant differences were observed in the allele or genotype frequencies of the NLRP3 polymorphisms between the controls and patients (P > 0.05). We found no significant differences for NLRP3 serum levels between PFAPA patients and controls (p > 0.05). Mutations in the MEFV gene were detected in 32.5% of our patients (13/40).

CONCLUSIONS

It seems that the synergistic effect of different genes plays a role in the formation of PFAPA syndrome. For this reason, it may be useful to examine the presence of mutations in genes such as NLRP3, MEFV, and CARD8 together while investigating the genetics of PFAPA syndrome. Key points • Familial cases of PFAPA syndrome have been reported suggesting a genetic basis for this syndrome. • Elevated serum or plasma levels of IL-1β, IL-6, and IL-18 have been demonstrated during PFAPA flares in several studies. • It seems that the synergistic effect of different genes plays a role in the formation of PFAPA syndrome.

NLRP3 Attenuates Intraocular Inflammation by Inhibiting AIM2-Mediated Pyroptosis Through the Phosphorylated Salt-Inducible Kinase 1/Sterol Regulatory Element Binding Transcription Factor 1 Pathway

OBJECTIVE

The NLRP3 inflammasome has been shown to be involved in the development of uveitis, but the exact mechanism remains elusive. This study was undertaken to explore the role of NLRP3 in the development of uveitis.

METHODS

First, Nlrp3-deficient mice were used to study the role of NLRP3 in experimental autoimmune diseases, such as experimental autoimmune uveitis (EAU) and experimental autoimmune encephalomyelitis (EAE). Next, the gathering of ASC, activation of caspase 1 and gasdermin D, and secretion of lactate dehydrogenase and interleukin-1β were detected to confirm macrophage pyroptosis and AIM2 activation in the Nlrp3^-/- mice. Additionally, RNA sequencing and chromatin immunoprecipitation-polymerase chain reaction were used to investigate the phosphorylated salt-inducible kinase 1 (p-SIK1)/sterol regulatory element binding transcription factor 1 (SREBF1) pathway, which regulates the transcription of Aim2. Finally, overexpression of Nlrp3 was applied to treat EAU.

RESULTS

Surprisingly, our findings show that NLRP3 plays an antiinflammatory role in 2 models of EAU and EAE. Additionally, macrophages show an increased M1 activation and pyroptosis in Nlrp3^-/- mice. Further experiments indicate that this pyroptosis of macrophages was mediated by the up-regulated transcription of Aim2 as a result of Nlrp3 deficiency. In mechanistic studies, Nlrp3 deficiency was implicated in the down-regulation of p-SIK1 and subsequently the up-regulation of SREBF1, which binds to Aim2 and then promotes the latter's transcription. Finally, Aim2 deficiency, RNA silencing of Aim2 or Srebf1, and overexpression of Nlrp3 resulted in attenuated inflammation of EAU.

CONCLUSION

Our data demonstrate that NLRP3 inhibits AIM2 inflammasome-mediated EAU by regulating the p-SIK1/SREBF1 pathway, highlighting the therapeutic potential of targeting Nlrp3.

Spotlight on pyroptosis: role in pathogenesis and therapeutic potential of ocular diseases

Pyroptosis is a programmed cell death characterized by swift plasma membrane disruption and subsequent release of cellular contents and pro-inflammatory mediators (cytokines), including IL‐1β and IL‐18. It differs from other types of programmed cell death such as apoptosis, autophagy, necroptosis, ferroptosis, and NETosis in terms of its morphology and mechanism. As a recently discovered form of cell death, pyroptosis has been demonstrated to be involved in the progression of multiple diseases. Recent studies have also suggested that pyroptosis is linked to various ocular diseases. In this review, we systematically summarized and discussed recent scientific discoveries of the involvement of pyroptosis in common ocular diseases, including diabetic retinopathy, age-related macular degeneration, AIDS-related human cytomegalovirus retinitis, glaucoma, dry eye disease, keratitis, uveitis, and cataract. We also organized new and emerging evidence suggesting that pyroptosis signaling pathways may be potential therapeutic targets in ocular diseases, hoping to provide a summary of overall intervention strategies and relevant multi-dimensional evaluations for various ocular diseases, as well as offer valuable ideas for further research and development from the perspective of pyroptosis.

Therapeutic Targeting of Inflammatory Pathways with Emphasis on NLRP3 Inflammasomes by Natural Products: A Novel Approach for the Treatment of Inflammatory Eye Diseases

There is an increase in the incidence of inflammatory eye diseases worldwide. Several dysregulated inflammatory pathways, including the NOD-like receptor protein 3 (NLRP3) inflammasome, have been reported to contribute significantly to the pathogenesis and progression of ophthalmic diseases. Although the available allopathic/conventional medicine has demonstrated effectiveness in managing eye diseases, there is an ongoing global demand for alternative therapeutics with minimal adverse drug reactions, easy availability, increase in patient-compliance, and better disease outcome. Therefore, several studies are investigating the utilization of natural products and herbal formulations in impeding inflammatory pathways, including the NLRP3 inflammasome, in order to prevent or manage eye diseases. In the present review, we highlight the recently reported inflammatory pathways with special emphasis on NLRP3 Inflammasomes involved in the development of eye diseases. Furthermore, we present a variety of natural products and phytochemicals that were reported to interfere with these pathways and their underlying mechanisms of action. These natural products represent potential therapeutic applications for the treatment of several inflammatory eye diseases.

Behçet's Syndrome in a Chinese Pedigree of NLRP3-Associated Autoinflammatory Disease: A Coexistence or Novel Presentation?

Objectives:NLRP3-associated autoinflammatory disease (NLRP3-AID) and Behçet's syndrome (BS) both belong to autoinflammatory diseases and rarely co-occur. Here we reported a Chinese pedigree of NLRP3-AID presented with BS.

Methods: We recorded a Chinese pedigree of NLRP3-AID presented with BS. Whole-exome sequencing was performed to find the hereditary susceptibility gene, and Sanger sequencing was performed on a consecutive cohort of 30 BS patients. We also reviewed the English literature on vasculitis associated with NLRP3-AID.

Results: The proband was a 45-year-old Chinese Han woman. She and her 12-year-old daughter presented with recurrent fevers, cold-induced urticaria, oral, and genital ulcers, conjunctivitis, uveitis, optic atrophy, erythema nodosum, headache, and hearing loss. They were initially suspected of having BS, and both responded poorly to corticosteroids and immunosuppressants, while anti-TNF therapy was moderately effective. Pedigree analysis revealed another four relatives with similar symptoms, and a heterozygous NLRP3 gene mutation c.1316C>T, p.Ala439Val was identified by whole-exome sequencing and Sanger sequencing. However, we did not discover NLRP3 gene mutation by Sanger sequencing in a confirmative cohort of 30 BS cases. A few case reports of vasculitis coexisting with NLRP3-AID, including a case of glomerulonephritis, and five cases of retinal vasculitis, were summarized through literature review.

Conclusions: Our study is the first report of NLRP3-AID associated with BS. The coexistence of NLRP3-AID and BS reveals the extensive heterogeneity of the pathogenesis of systemic autoinflammatory diseases and calls for specific therapeutics.

The role of the inflammasomes in the pathogenesis of uveitis

Uveitis is a diverse group of sight-threatening intraocular inflammatory diseases usually causing eye redness, pain, blurred vision, and sometimes blindness. Although the exact pathogenesis of uveitis is not yet clear, accumulating evidences have shown that an imbalanced regulation of immune responses caused by a combination of genetic and environmental factors are implicated in the pathogenesis of this disease. As critical regulators of inflammation, inflammasomes have been assumed to play a role in the pathogenesis of uveitis. Recent studies have reported the association between a number of genetic variants in inflammasome related genes (such as NLRP3, NLRP1, NLRC4 and AIM2) with increased risk to uveitis. Mounting evidence have shown an aberrant activation of the NLRP3 inflammasome in both uveitis patients and murine models of uveitis. Some studies explored the intervention of uveitis via modulating inflammasome activity in the eye. This review aims at summarizing the main findings of these studies, proposing the possible mechanism whereby inflammasomes affect the susceptibility to develop uveitis, and giving a perspective for future studies, which may further improve our understanding about the role of inflammasomes and related cytokines in the pathogenesis of uveitis, and may hopefully lead to new therapeutics by targeting inflammasomes.

Plasma exosomes derived from patients with intestinal Behçet's syndrome induce intestinal epithelial cell pyroptosis

OBJECTIVES

Intestinal Behçet's syndrome (IBS) has high morbidity and mortality rates with serious complications. The purpose of this study was to investigate the expression of pyroptosis-related proteins in the intestinal tissues of IBS patients and explore the role of plasma exosomes derived from IBS patients in the pyroptosis of intestinal epithelial cells.

METHOD

Immunohistochemistry was used to investigate the expression of nucleotide-binding domain-like receptor protein 3 (NLRP3), caspase-1, and gasdermin D (GSDMD). Quantitative real-time PCR was employed to measure the mRNA levels of IL-1β and IL-18 in the intestinal tissues. Plasma exosomes were isolated and observed by transmission electron microscopy. The exosomes were co-cultured with intestinal epithelial cells in vitro. Western blot was used to measure the expression of pyroptosis-related proteins including NLRP3, full-length GSDMD, N-terminal GSDMD, pro-caspase-1, and cleaved caspase-1. The levels of IL-1β and IL-18 were detected by enzyme-linked immunosorbent assay. Cell death was measured by using the lactate dehydrogenase (LDH) release assay.

RESULTS

Expression of NLRP3 (12.2% ± 1.2%, 8.1% ± 0.9%, t = 4.692, p = 0.009), caspase-1 (24.6% ± 2.1%, 4.2% ± 1.8%, t = 12.842, p = 0.000), and GSDMD (16.6% ± 1.9%, 9.8% ± 1.3%, t = 5.194, p = 0.007) were significantly increased in the intestinal tissues of patients with IBS compared with normal control (NC) group, respectively. The relative mRNA levels of IL-1β (t = 4.308, p = 0.005) and IL-18 (t = 3.096, p = 0.021) in the intestinal tissues were significantly higher in IBS patients than in NC group, while the protein levels of IL-1β (t = 3.873, p = 0.018) and IL-18 (t = 4.389, p = 0.012) were also significantly increased, which was consistent with the results of the relative mRNA levels. Moreover, we found that exosomes from IBS patients significantly induced pyroptosis of intestinal epithelial cells via the activation of NLRP3 inflammasome in vitro experiments.

CONCLUSIONS

Plasma exosomes derived from IBS patients may induce pyroptosis of intestinal epithelial cells via the activation of NLRP3 inflammasome. Key Points •The role of exosomes in IBS is first reported in this study. • In this study, we explored the mechanism that plasma exosomes derived from IBS patients may induce pyroptosis of intestinal epithelial cells via the activation of NLRP3 inflammasome.

Whole-Exome Sequencing of Patients With Posterior Segment Uveitis

OBJECTIVE

To elucidate molecular risk factors for posterior segment uveitis using a functional genomics approach.

DESIGN

Genetic association cohort study.

METHODS

Setting: Single-center study at an academic referral center.

STUDY POPULATION

164 patients with clinically diagnosed uveitis of the posterior segment.

MAIN OUTCOME MEASURES

Exome sequencing was used to detect variants identified in 164 patients with posterior segment uveitis. A phenotype-driven analysis, protein structural modeling, and in silico calculations were then used to rank and predict the functional consequences of key variants.

RESULTS

A total of 203 single nucleotide variants, in 23 genes across 164 patients, were included in this study. Both known and novel variants were identified in genes previously implicated in specific types of syndromic uveitis-such as NOD2 (Blau syndrome) and CAPN5 NIV (neovascular inflammatory vitreoretinopathy)-as well as variants in genes not previously linked to posterior segment uveitis. Based on a ranked list and protein-protein-interaction network, missense variants in NOD-like receptor family genes (NOD2, NLRC4, NLRP3, and NLRP1), CAPN5, and TYK2 were characterized via structural modeling and in silico calculations to predict how specific variants might alter protein structure and function. The majority of analyzed variants were notably different from wild type.

CONCLUSIONS

This study implicates new pathways and immune signaling proteins that may be associated with posterior segment uveitis susceptibility. A larger cohort and functional studies will help validate the pathogenicity of the mutations identified. In specific cases, whole-exome sequencing can help diagnose nonsyndromic uveitis in patients harboring known variants for syndromic inflammatory diseases.

Computational Modeling of NLRP3 Identifies Enhanced ATP Binding and Multimerization in Cryopyrin-Associated Periodic Syndromes

Cyropyrin-associated periodic syndromes (CAPS) are clinically distinct syndromes that encompass a phenotypic spectrum yet are caused by alterations in the same gene, NLRP3. Many CAPS cases and other NLRP3-autoinflammatory diseases (NLRP3-AIDs) are directly attributed to protein-coding alterations in NLRP3 and the subsequent dysregulation of the NLRP3 inflammasome leading to IL-1β-mediated inflammatory states. Here, we used bioinformatics tools, computational modeling, and computational assessments to explore the proteomic consequences of NLRP3 mutations, which potentially drive NLRP3 inflammasome dysregulation. We analyzed 177 mutations derived from familial cold autoinflammatory syndrome (FCAS), Muckle-Wells Syndrome (MWS), and the non-hereditary chronic infantile neurologic cutaneous and articular syndrome, also known as neonatal-onset multisystem inflammatory disease (CINCA/NOMID), as well as other NLRP3-AIDs. We found an inverse relationship between clinical severity and the severity of predicted structure changes resulting from mutations in NLRP3. Bioinformatics tools and computational modeling revealed that NLRP3 mutations that are predicted to be structurally severely-disruptive localize around the ATP binding pocket and that specific proteo-structural changes to the ATP binding pocket lead to enhanced ATP binding affinity by altering hydrogen-bond and charge interactions. Furthermore, we demonstrated that NLRP3 mutations that are predicted to be structurally mildly- or moderately-disruptive affect protein-protein interactions, such as NLRP3-ASC binding and NLRP3-NLRP3 multimerization, enhancing inflammasome formation and complex stability. Taken together, we provide evidence that proteo-structural mechanisms can explain multiple mechanisms of inflammasome activation in NLRP3-AID.

Correlation of Tumor Necrosis Factor-α -308G>A Polymorphism with Susceptibility, Clinical Manifestations, and Severity in Behçet Syndrome: Evidences from an Italian Genetic Case-Control Study

To investigate the association between a functional drug-response tumor necrosis factor (TNF)α gene polymorphism (at the positions of -308; rs1800629; NG_007462.1:g.4682G>A) and both disease susceptibility and clinical manifestations in a cohort of 130 Italian patients with Behçet syndrome (BS). A group of 100 ethnically, age, and gender matched healthy controls (HC) was also recruited. Genotyping was performed using molecular (amplification and direct sequencing) and in silico methods. The genotype distribution of BS patients and HC underlined a lower percentage of wild-type GG genotype in BS patients versus HC (106/130 patients, 81.5% vs. 91/100 HC, 91%; p < 0.05), while the heterozygous genotype (GA) was identified in 24/130 patients (18.5%) versus 9/100 HC (9%) (p < 0.05). GA genotype was significantly associated with the disease (odds ratio = 2.29, 95% confidence interval 1.01-5.18). No significant association was recognized between the single nucleotide polymorphism (SNP) and the BS clinical manifestations, as well as with disease severity (Krause's index). We found statistically significant higher frequency of TNFα rs1800629 GA genotype in patients than in controls. No significant association was recognized between the polymorphism and the clinical parameters, as well as between the SNP and the disease severity. Our data need to be confirmed in larger cohort of patients and matched controls.

Enhanced NLRP3 and DEFA1B Expression During the Active Stage of Parenchymal Neuro-Behçet's Disease

BACKGROUND/AIM

Neurological symptoms (neuro-Behçet's disease; NBD) occur in a fraction of Behçet's disease (BD) patients and often present with parenchymal brain lesions and clinical exacerbations. Our aim was to identify genes associated with attack and remission periods of NBD.

MATERIALS AND METHODS

Microarray analysis was performed using peripheral blood mononuclear cell (PBMC) samples obtained during attack and remission periods of five NBD patients. Expression levels of the most significantly up-regulated genes were measured with real-time PCR using PBMC samples of 15 NBD patients and 20 healthy controls.

RESULTS

During NBD attacks, the most remarkably up-regulated genes were defensin alpha 1B (DEFA1B) and NLR family, pyrin domain containing 3 (NLRP3). Real time PCR studies showed significantly increased DEFA1B and NLRP3 expression levels during attacks.

CONCLUSION

Immunological factors showing the most significant increase in expression during NBD attacks were primarily associated with innate immunity functions. DEFA1B and NLRP3 can be used as biomarkers for estimation of disease activity in NBD.

Inflammasomes and autoimmune and rheumatic diseases: A comprehensive review

Inflammasomes are a multi-protein platform forming a part of the innate immune system. Inflammasomes are at standby status and can be activated when needed. Inflammasome activation is an important mechanism for the production of active interleukin (IL)-1β and IL-18, which have important roles to instruct adaptive immunity. Active forms of inflammasomes trigger a series of inflammatory cascades and lead to the differentiation and polarization of naïve T cells and secretion of various cytokines, which can induce various kinds of autoimmune and rheumatic diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), gout, Sjögren's syndrome, Behçet's disease, anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis and IgA vasculitis (former Henoch-Schönlein purpura ). In this review, we summarize studies published on inflammasomes and review their roles in various autoimmune diseases. Understanding of the role of inflammasomes may facilitate the diagnosis of autoimmune diseases and the development of tailored therapies in the future.

Identification of a de novo NLRP3 gene variation in an Italian Behçet syndrome patient

A novel nonsynonymous variation of NLRP3 was identified in an Italian patient with Behçet syndrome using both bioinformatics and molecular methods. This variation was a thymine to guanine polymorphism responsible for the isoleucine to serine amino acid change at position 348. The novel variation was predicted to be a pathogenic allele.

De novo ATP1A3 and compound heterozygous NLRP3 mutations in a child with autism spectrum disorder, episodic fatigue and somnolence, and muckle-wells syndrome

Complex phenotypes may represent novel syndromes that are the composite interaction of several genetic and environmental factors. We describe an 9-year old male with high functioning autism spectrum disorder and Muckle-Wells syndrome who at age 5  years of age manifested perseverations that interfered with his functioning at home and at school. After age 6, he developed intermittent episodes of fatigue and somnolence lasting from hours to weeks that evolved over the course of months to more chronic hypersomnia. Whole exome sequencing showed three mutations in genes potentially involved in his clinical phenotype. The patient has a predicted pathogenic de novo heterozygous p.Ala681Thr mutation in the ATP1A3 gene (chr19:42480621C>T, GRCh37/hg19). Mutations in this gene are known to cause Alternating Hemiplegia of Childhood, Rapid Onset Dystonia Parkinsonism, and CAPOS syndrome, sometimes accompanied by autistic features. The patient also has compound heterozygosity for p.Arg490Lys/p.Val200Met mutations in the NLRP3 gene (chr1:247588214G>A and chr1:247587343G>A, respectively). NLRP3 mutations are associated in an autosomal dominant manner with clinically overlapping auto-inflammatory conditions including Muckle-Wells syndrome. The p.Arg490Lys is a known pathogenic mutation inherited from the patient's father. The p.Val200Met mutation, inherited from his mother, is a variant of unknown significance (VUS). Whether the de novoATP1A3mutation is responsible for or plays a role in the patient's episodes of fatigue and somnolence remains to be determined. The unprecedented combination of two NLRP3 mutations may be responsible for other aspects of his complex phenotype.

The Inflammasomes in Cardiovascular Disease

Cardiovascular disease (CVD) is the number one cause of death worldwide. The pathogenesis of various disease entities that comprise the area of CVD is complex and multifactorial. Inflammation serves a central role in these complex aetiologies. The inflammasomes are intracellular protein complexes activated by danger-associated molecular patterns (DAMPs) present in CVD such as atherosclerosis and myocardial infarction (MI). After a two-step process of priming and activation, inflammasomes are responsible for the formation of pro-inflammatory cytokines interleukin-1β and interleukin-18, inducing a signal transduction cascade resulting in a strong immune response that culminates in disease progression. In the past few years, increased interest has been raised regarding the inflammasomes in CVD. Inflammasome activation is thought to be involved in the pathogenesis of various disease entities such as atherosclerosis, MI and heart failure (HF). Interference with inflammasome-mediated signalling could reduce inflammation and attenuate the severity of disease. In this chapter we provide an overview of the current literature available on the role of inflammasome inhibition as a therapeutic intervention and the possible clinical implications for CVD.

Increased senescent CD8+ T cells in the peripheral blood mononuclear cells of Behçet's disease patients

Behçet's disease (BD) is a chronic inflammatory disease characterized by recurrent mucocutaneous, ocular, and skin lesions. Immunosenescence is associated with increased susceptibility to infection and chronic low grade inflammation. This study aimed to investigate the differences in the frequencies of immunosenescent cells in the peripheral blood mononuclear cells (PBMCs) of patients with BD. PBMCs were isolated from age-matched patients with active BD (n = 19), inactive BD (n = 20), disease controls (DCs, n = 15) and healthy controls (HCs, n = 15). The frequencies of senescent CD4+ T cells (CD3+ CD4+ CD27- CD28- cells), CD8+ T cells (CD3+ CD8+ CD27- CD28- cells) and B cells (CD19+ CD27- IgD- cells) were analyzed using flow cytometry. Senescence-associated β galactosidase activity was also measured in CD8+ T cells using flow cytometry with 5-dodecanoylaminofluorescein di-β-D-galactopyranoside. Frequencies of senescent CD4+ and CD19+ cells were not significantly different between the groups. The frequency of senescent CD8+ T cells was significantly higher in active BD than in DCs and HCs. C-reactive protein and erythrocyte sedimentation rate levels, which indicate disease activity, did not correlate with increased frequencies of immunosenescent cells. Steroid treatment, specific organ involvement, and HLA-B51 status did not have a significant influence on the frequencies of immunosenescent cells. Frequencies of senescence-associated β galactosidase+ CD8+ T cells were significantly higher in active BD and inactive BD compared to DCs and HCs. There was an increased frequency of senescent CD8+ T cells in the PBMCs of patients with BD.

Inflammasomes, the eye and anti-inflammasome therapy

Inflammasomes, key molecular regulators that play an important role in inflammation, consist of a central protein, an adaptor protein ASC (apoptosis speck-like protein) and a caspase-1 protein. Upon activation, caspase-1 induces maturation of cytokines such as interleukin-1β (IL-1β) and interleukin-18 (IL-18). The release of these cytokines can result in inflammation. Inflammasomes are activated by a variety of factors and their activation involves complex signalling leading to resolution of infection, but can also contribute to the pathology of inflammatory, autoimmune, and infectious diseases. The role of NLRP1, NLRP3, NLRC4 and AIM2 inflammasomes in the pathogenesis of ocular diseases such as glaucoma, age related macular degeneration (AMD), diabetic retinopathy, dry eye and infections of the eye has been established over the past decade. In experimental studies and models, inhibition of inflammasomes generally helps to reduce the inflammation associated with these eye diseases, but as yet the role of these inflammasomes in many human eye diseases is unknown. Therefore, a need exists to study and understand various aspects of inflammasomes and their contribution to the pathology of human eye diseases. The goal of this review is to discuss the role of inflammasomes in the pathology of eye diseases, scope for anti-inflammasome therapy, and current research gaps in inflammasome-related eye disease.

Evidence for genetic overlap between adult onset Still's disease and hereditary periodic fever syndromes

OBJECTIVE

Adult onset Still's disease (AOSD) is a severe, autoimmune disease that can be challenging to treat with conventional therapeutics and biologicals in a considerable number of cases. Therefore, there is a high need to understand its pathogenesis better. As major clinical symptoms overlap between AOSD and hereditary periodic fever syndromes (HPFS), we analysed four known HPFS genes in AOSD.

METHODS

We performed Sanger sequencing and quantitative analysis of all coding regions of MEFV, TNFRSF1A, MVK and NLRP3 in 40 AOSD patients. All rare coding variants (n = 6) were evaluated for several aspects to classify them as benign to pathogenic variants. Statistical analysis was performed to analyse whether variants classified as (likely) pathogenic were associated with AOSD.

RESULTS

We identified three rare variants in MEFV, one previously not described. Association to the three likely pathogenic MEFV variants was significant (p _c = 2.34E- 03), and two of the three carriers had a severe course of disease. We observed strong evidence for significant association to mutations in TNFRSF1A (p _c = 2.40E- 04), as 5% of patients (2/40) carried a (likely) pathogenic variant in this gene. Both of them received a biological for treatment.

CONCLUSION

Our results indicate TNFRSF1A as a relevant gene in AOSD, especially in patients with a more challenging course of disease, while causal variants remain to be identified in the majority of patients.

Inflammasomes and dermatology

Inflammasomes are intracellular multiprotein complexes that comprise part of the innate immune response. Since their definition, inflammasome disorders have been linked to an increasing number of diseases. Autoinflammatory diseases refer to disorders in which local factors lead to the activation of innate immune cells, causing tissue damage when in the absence of autoantigens and autoantibodies. Skin symptoms include the main features of monogenic inflammasomopathies, such as Cryopyrin-Associated Periodic Syndromes (CAPS), Familial Mediterranean Fever (FMF), Schnitzler Syndrome, Hyper-IgD Syndrome (HIDS), PAPA Syndrome, and Deficiency of IL-1 Receptor Antagonist (DIRA). Concepts from other pathologies have also been reviewed in recent years, such as psoriasis, after the recognition of a combined contribution of innate and adaptive immunity in its pathogenesis. Inflammasomes are also involved in the response to various infections, malignancies, such as melanoma, autoimmune diseases, including vitiligo and lupus erythematosus, atopic and contact dermatitis, acne, hidradenitis suppurativa, among others. Inhibition of the inflammasome pathway may be a target for future therapies, as already occurs in the handling of CAPS, through the introduction of IL-1 inhibitors. This study presents a literature review focusing on the participation of inflammasomes in skin diseases.

Infliximab therapy for intestinal, neurological, and vascular involvement in Behcet disease: Efficacy, safety, and pharmacokinetics in a multicenter, prospective, open-label, single-arm phase 3 study

Behçet disease (BD) is a multisystem disease associated with a poor prognosis in cases of gastrointestinal, neurological, or vascular involvement. We conducted a multicenter, prospective, open-label, single-arm phase 3 study to determine the efficacy, safety, and pharmacokinetics of infliximab (IFX) in BD patients with these serious complications who had displayed poor response or intolerance to conventional therapy.IFX at 5 mg/kg was administered to 18 patients (11 intestinal BD, 3 neurological BD [NBD], and 4 vascular BD [VBD]) at weeks 0, 2, and 6 and every 8 weeks thereafter until week 46. In patients who showed inadequate responses to IFX after week 30, the dose was increased to 10 mg/kg. We then calculated the percentage of complete responders according to the predefined criteria depending on the symptoms and results of examinations (ileocolonoscopy, brain magnetic resonance imaging, computed tomography angiography, positron emission tomography, cerebrospinal fluid, or serum inflammatory markers), exploring the percentage of complete responders at week 30 (primary endpoint).The percentage of complete responders was 61% (11/18) at both weeks 14 and 30 and remained the same until week 54. Intestinal BD patients showed improvement in clinical symptoms along with decrease in C-reactive protein (CRP) levels after week 2. Consistently, scarring or healing of the principal ulcers was found in more than 80% of these patients after week 14. NBD patients showed improvement in clinical symptoms, imaging findings, and cerebrospinal fluid examinations. VBD patients showed improvement in clinical symptoms after week 2 with reductions in CRP levels and erythrocyte sedimentation rate. Imaging findings showed reversal of inflammatory changes in 3 of the 4 VBD patients. Irrespective of the type of BD, all patients achieved improvement in quality of life, leading to the dose reduction or withdrawal of steroids. IFX dose was increased to 10 mg/kg in 3 intestinal BD patients, resulting in the improvement of clinical symptoms, CRP levels, and visual analogue scale score. Safety and pharmacokinetics profiles were comparable to those in patients with rheumatoid arthritis or Crohn disease. These findings support IFX as a new therapeutic option for patients with intestinal BD, NBD, or VBD.

Methylation Status of Alu and LINE-1 Interspersed Repetitive Sequences in Behcet's Disease Patients

Behcet's Disease (BD) is a multisystem chronic inflammatory disease. The pathology is believed to involve both genetic susceptibility and environmental factors. Hypomethylation leading to activation of interspersed repetitive sequences (IRSs) such as LINE-1 and Alu contributes to the pathologies of autoimmune diseases and cancer. Herein, the epigenetic changes of IRSs in BD were evaluated using combined bisulfite restriction analysis-interspersed repetitive sequences (COBRA-IRS). DNA from neutrophils and peripheral blood mononuclear cells (PBMCs) of BD patients with ocular involvement that were in active or inactive states and healthy controls were used to analyze LINE-1 and Alu methylation levels. For Alu sequences, significant differences were observed in the frequency of ^uC^uC alleles between PBMCs of patients and controls (p = 0.03), and between inactive patients and controls (p = 0.03). For neutrophils, the frequency of ^uC^uC was significantly higher between patients and controls (p = 0.006) and between inactive patients and controls (p = 0.002). The partial methylation (^uC^mC + ^mC^uC) frequencies of Alu between inactive patients and control samples also differed (p = 0.02). No statistically significant differences for LINE-1 were detected. Thus, changes in the methylation level of IRS elements might contribute to the pathogenesis of BD. The role of Alu transcripts in BD should be investigated further.