Mutations in the B30.2 and the central helical scaffold domains of pyrin differentially affect inflammasome activation.

Familial Mediterranean Fever (FMF) is the most common monogenic autoinflammatory disorder. FMF is caused by mutations in the MEFV gene, encoding pyrin, an inflammasome sensor. The best characterized pathogenic mutations associated with FMF cluster in exon 10. Yet, mutations have been described along the whole MEFV coding sequence. Exon 10 encodes the B30.2 domain of the pyrin protein, but the function of this human-specific domain remains unclear. Pyrin is an inflammasome sensor detecting RhoA GTPase inhibition following exposure to bacterial toxins such as TcdA. Here, we demonstrate that the B30.2 domain is dispensable for pyrin inflammasome activation in response to this toxin. Deletion of the B30.2 domain mimics the most typical FMF-associated mutation and confers spontaneous inflammasome activation in response to pyrin dephosphorylation. Our results indicate that the B30.2 domain is a negative regulator of the pyrin inflammasome that acts independently from and downstream of pyrin dephosphorylation. In addition, we identify the central helical scaffold (CHS) domain of pyrin, which lies immediately upstream of the B30.2 domain as a second regulatory domain. Mutations affecting the CHS domain mimic pathogenic mutations in the B30.2 domain and render the pyrin inflammasome activation under the sole control of the dephosphorylation. In addition, specific mutations in the CHS domain strongly increase the cell susceptibility to steroid catabolites, recently described to activate pyrin, in both a cell line model and in monocytes from genotype-selected FMF patients. Taken together, our work reveals the existence of two distinct regulatory regions at the C-terminus of the pyrin protein, that act in a distinct manner to regulate positively or negatively inflammasome activation. Furthermore, our results indicate that different mutations in pyrin regulatory domains have different functional impacts on the pyrin inflammasome which could contribute to the diversity of pyrin-associated autoinflammatory diseases.

Transcriptional licensing is required for Pyrin inflammasome activation in human macrophages and bypassed by mutations causing familial Mediterranean fever.

Pyrin is a cytosolic immune sensor that nucleates an inflammasome in response to inhibition of RhoA by bacterial virulence factors, triggering the release of inflammatory cytokines, including IL-1ß. Gain-of-function mutations in the MEFV gene encoding Pyrin cause autoinflammatory disorders, such as familial Mediterranean fever (FMF) and Pyrin-associated autoinflammation with neutrophilic dermatosis (PAAND). To precisely define the role of Pyrin in pathogen detection in human immune cells, we compared initiation and regulation of the Pyrin inflammasome response in monocyte-derived macrophages (hMDM). Unlike human monocytes and murine macrophages, we determined that hMDM failed to activate Pyrin in response to known Pyrin activators Clostridioides difficile (C. difficile) toxins A or B (TcdA or TcdB), as well as the bile acid analogue BAA-473. The Pyrin inflammasome response was enabled in hMDM by prolonged priming with either LPS or type I or II interferons and required an increase in Pyrin expression. Notably, FMF mutations lifted the requirement for prolonged priming for Pyrin activation in hMDM, enabling Pyrin activation in the absence of additional inflammatory signals. Unexpectedly, in the absence of a Pyrin response, we found that TcdB activated the NLRP3 inflammasome in hMDM. These data demonstrate that regulation of Pyrin activation in hMDM diverges from monocytes and highlights its dysregulation in FMF.

Steroid hormone catabolites activate the pyrin inflammasome through a non-canonical mechanism.

The pyrin inflammasome acts as a guard of RhoA GTPases and is central to immune defenses against RhoA-manipulating pathogens. Pyrin activation proceeds in two steps. Yet, the second step is still poorly understood. Using cells constitutively activated for the pyrin step 1, a chemical screen identifies etiocholanolone and pregnanolone, two catabolites of testosterone and progesterone, acting at low concentrations as specific step 2 activators. High concentrations of these metabolites fully and rapidly activate pyrin, in a human specific, B30.2 domain-dependent manner and without inhibiting RhoA. Mutations in MEFV, encoding pyrin, cause two distinct autoinflammatory diseases pyrin-associated autoinflammation with neutrophilic dermatosis (PAAND) and familial Mediterranean fever (FMF). Monocytes from PAAND patients, and to a lower extent from FMF patients, display increased responses to these metabolites. This study identifies an unconventional pyrin activation mechanism, indicates that endogenous steroid catabolites can drive autoinflammation, through the pyrin inflammasome, and explains the "steroid fever" described in the late 1950s upon steroid injection in humans.

The pyrin inflammasome aggravates inflammatory cell migration in patients with familial Mediterranean fever.

BACKGROUND: Familial Mediterranean fever (FMF) is an autoinflammatory disease caused by pathogenic variants of the MEFV gene, which encodes pyrin. Leukocyte migration to serosal sites is a key event during inflammation in FMF. The pyrin inflammasome is a multiprotein complex involved in inflammation. Here, we aimed to determine the relationship between inflammatory cell migration and the pyrin inflammasome in FMF patients. METHODS: Monocytes were isolated from blood samples collected from patients with FMF, healthy controls, and a patient with cryopyrin-associated periodic syndrome (CAPS), which served as a disease control. Inflammasome proteins were analyzed under inflammasome activation and inhibition by western blotting. Cell migration assays were performed with the isolated primary monocytes as well as THP-1 monocytes and THP-1-derived macrophages. RESULTS: When the pyrin inflammasome was suppressed, migration of monocytes from FMF patients was significantly decreased compared to the migration of monocytes from the CAPS patient and healthy controls. Cell line experiments showed a relationship between pyrin inflammasome activation and cell migration. CONCLUSIONS: These findings suggest that the increased cell migration in FMF is due to the presence of more active pyrin inflammasome. This study contributes to our understanding of the role of pyrin in inflammatory cell migration through inflammasome formation. IMPACT: The pyrin inflammasome may play a role in inflammatory cell migration. FMF patients show a pyrin inflammasome-dependent increase in inflammatory cell migration. Correlations between the pyrin inflammasome and cell migration were observed in both THP-1 monocytes and THP-1-derived macrophages.

The PRY/SPRY domain of pyrin/TRIM20 interacts with ß2-microglobulin to promote inflammasome formation.

Pyrin/TRIM20 is expressed in the neutrophils and monocytes/macrophages and regulates caspase-1 activation and interleukin-1ß maturation. Although the mutations in the PRY/SPRY domain of pyrin cause familial Mediterranean fever (FMF), the mechanism of how mutated pyrin provokes excessive inflammation in FMF patients is not well understood. The present study investigated the role of pyrin/TRIM20 in inflammation and the pathogenesis of FMF. ß2-Microglobulin (ß2MG) was identified as the novel pyrin ligand binding to the PRY/SPRY domain by yeast two-hybrid screenings and co-immunoprecipitation analysis. ß2MG was co-localized with pyrin not only in the HEK293 cells overexpressing these proteins but also in the monosodium urate-stimulated human neutrophils in the speck-like structures. The pyrin-ß2MG interaction triggered the binding of pyrin and proline-serine-threonine phosphatase interacting protein 1 (PSTPIP1) and then the subsequent recruitment of apoptosis-associated speck-like protein containing caspase recruitment domain (ASC). Caspase-1 p20 subunit, produced by pyrin inflammasome, also interacted with the pyrin PRY/SPRY domain and inhibited the pyrin-ß2MG interaction. FMF-associated pyrin mutation M694V did not affect pyrin-ß2MG interaction but weakened this inhibition. Our findings suggest that ß2MG functions as the pyrin ligand inducing pyrin inflammasome formation and that the FMF-associated pyrin mutations weakened negative feedback of caspase-1 p20 subunit.

Transmigration of Neutrophils From Patients With Familial Mediterranean Fever Causes Increased Cell Activation.

Familial Mediterranean fever (FMF) is caused by pyrin-encoding MEFV gene mutations and characterized by the self-limiting periods of intense inflammation, which are mainly mediated by a massive influx of polymorphonuclear neutrophils (PMNs) into the inflamed sites. Perturbation of actin polymerization by different pathogens was shown to activate the pyrin inflammasome. Our aim was to test whether cytoskeletal dynamics in the absence of pathogens may cause abnormal activation of PMNs from FMF patients. We also aimed to characterize immunophenotypes of circulating neutrophils and their functional activity. Circulating PMNs displayed heterogeneity in terms of cell size, granularity and immunophenotypes. Particularly, PMNs from the patients in acute flares (FMF-A) exhibited a characteristic of aged/activated cells (small cell size and granularity, up-regulated CXCR4), while PMNs form the patients in remission period (FMF-R) displayed mixed fresh/aged cell characteristics (normal cell size and granularity, up-regulated CD11b, CD49d, CXCR4, and CD62L). The findings may suggest that sterile tissue-infiltrated PMNs undergo reverse migration back to bone marrow and may explain why these PMNs do not cause immune-mediated tissue damage. A multidirectional expression of FcγRs on neutrophils during acute flares was also noteworthy: up-regulation of FcγRI and down-regulation of FcγRII/FcγRIII. We also observed spontaneous and fMPL-induced activation of PMNs from the patients after transmigration through inserts as seen by the increased expression of CD11b and intracellular expression of IL-1ß. Our study suggests heightened sensitivity of mutated pyrin inflammasome towards cytoskeletal modifications in the absence of pathogens.

Pyrin Inflammasome Activation Abrogates Interleukin-1 Receptor Antagonist, Suggesting a New Mechanism Underlying Familial Mediterranean Fever Pathogenesis.

OBJECTIVE: Aberrant pyrin inflammasome activity triggers familial Mediterranean fever (FMF) pathogenesis, but the exact mechanism remains elusive and an obstacle to efficient treatment. We undertook this study to identify pyrin inflammasome-specific mechanisms to improve FMF treatment and diagnostics in the future. METHODS: Pyrin-specific protein secretion was assessed by proteome analysis in U937-derived macrophages, and specific findings were confirmed in pyrin inflammasome-activated monocytes from healthy blood donors and patients with FMF, stratified according to MEFV genotype categories corresponding to a suspected increase in FMF disease severity. RESULTS: Proteome data revealed a differential secretion pattern of interleukin-1 receptor antagonist (IL-1Ra) from pyrin- and NLRP3-activated U937-derived macrophages, which was verified by enzyme-linked immunosorbent assay and quantitative polymerase chain reaction. Moreover, pyrin activation significantly reduced IL1RN messenger RNA expression (P < 0.001) and IL-1Ra secretion (P < 0.01) in healthy donor and FMF monocytes, respectively. Independent of MEFV genotype, unstimulated FMF monocytes from colchicine-treated patients secreted lower amounts of IL-1Ra compared to healthy donors (P < 0.05) and displayed decreased ratios of IL-1Ra:IL-1ß (P < 0.05), suggesting a reduced antiinflammatory capacity. CONCLUSION: Our data show an inherent lack of IL-1Ra expression specific to pyrin inflammasome activation, suggesting a new mechanism underlying FMF pathogenesis. The reduced IL-1Ra levels in FMF monocytes suggest a diminished antiinflammatory capacity that potentially leaves FMF patients sensitive to proinflammatory stimuli, regardless of receiving colchicine therapy. Thus, considering the potential clinical consequence of reduced monocyte IL-1Ra secretion in FMF patients, we suggest further investigation into IL-1Ra dynamics and its potential implications for FMF treatment in the future.

Soluble TREM-1 Levels in Familial Mediterranean Fever Related AA-Amyloidosis.

Objectives: Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) is a monocyte and neutrophil receptor functioning in innate immunity. TREM-1 activity has been studied in various autoimmune diseases such as RA and SLE but there is no data in autoinflammatory pathologies. We studied soluble TREM-1 (sTREM-1) activity in Familial Mediterranean Fever (FMF) cases to evaluate the clinical role of TREM-1 in amyloidosis. Methods: The study includes 62 patients with FMF (42 with amyloidosis) who are regular attendees of a tertiary center for autoinflammatory diseases. For control purposes, 5 patients with AA amyloidosis secondary to other inflammatory diseases, and 20 healthy individuals were also included. Soluble TREM-1 levels were measured using enzyme-linked immunosorbent assay (ELISA). All FMF patients were in an attack-free period during the collection of the blood samples.Results: Soluble TREM-1 levels were found to be significantly higher in the FMF amyloidosis group compared to FMF without amyloidosis group and healthy controls (p = .001 and 0.002). Nevertheless, this difference between sTREM-1 levels was not found among FMF amyloidosis and other AA amyloidosis groups (p = .447) as well as between only FMF patients and healthy controls (p = .532). Soluble TREM-1 levels were found in correlation with creatinine and CRP in the FMF patient group regardless of their amyloidosis diagnosis (r = 0.314, p = .013; r = 0.846, p < .001).Conclusion: TREM-1 seems to be related to renal function rather than disease activity in FMF. Its role as an early diagnostic marker of amyloidosis in FMF complicated with AA amyloidosis should be tested in larger patient groups.

The systemic autoinflammatory disorders for dermatologists. Part 1: overview.

The systemic autoinflammatory disorders (SAIDs) or periodic fever syndromes are disorders of innate immunity, which can be inherited or acquired. They are almost all very rare and easily overlooked; typically, patients will have seen multiple specialities prior to diagnosis, so a high level of clinical suspicion is key. It is important to note that these are 'high-value' diagnoses as the majority of these syndromes can be very effectively controlled, dramatically improving quality of life and providing protection against the development of irreversible complications such as AA amyloidosis. In this article, we take an overview of SAIDs and look at the common features; in Part 2, we take a more in-depth look at the better recognized or more dermatologically relevant conditions.

The Use of Interleukine-1 Inhibitors in Familial Mediterranean Fever Patients: A Narrative Review.

Purpose: Familial Mediterranean fever (FMF) is the most common monogenic auto-inflammatory disease characterized by recurrent attacks of fever and serositis. It is associated with mutation in pyrin inflammasome leading to interleukin-1 (IL-1) over secretion. Although colchicine is the first line treatment in FMF, 5-10% of patients are reported in literature as non-responders. Colchicine is not always well-tolerated due either to its direct toxicity or to co-morbidities that preclude the administration of its proper dosage. For these patients an alternative or additional treatment to colchicine is necessary. This literature review reports the published data regarding the use of IL-1 inhibitors in Familial Mediterranean Fever. Results: There is no uniform definition of colchicine resistance, but the different studies of treatment with IL-1 inhibitors provide evidence of IL-1 pathogenic role in colchicine-resistant FMF. IL-1 inhibition is an efficacious option for controlling and preventing flares -at least at the short term- in FMF patients who are insufficiently controlled with colchicine alone. Although canakinumab is the only approved drug in Europe for colchicine resistant FMF treatment, experience with anakinra is also substantial. In the absence of comparative studies both treatments seem to be an equal option for the management of these patients. Overall the safety profile of IL-1 inhibitors seems not different in FMF patients than in the other diseases and can be considered as globally safe. The main side effects are local injection site reactions and infections. Conclusion: IL-1 inhibitors have the potential to improve patient outcome even in FMF patients with co-morbidities or severe complications in whom inflammation control is difficult to achieve with colchicine alone. Nevertheless, current data are limited and further evaluation of long-term efficacy and safety of IL-1 inhibitors are necessary, in order to provide robust evidence in this domain.

Prevalence of Nonalcoholic Fatty Liver Disease in Familial Mediterranean Fever.

INTRODUCTION: Nonalcoholic fatty liver disease (NAFLD) is closely associated with metabolic syndrome (MetS), insulin resistance (IR) and chronic inflammation. Although familial Mediterranean fever (FMF) patients have no symptoms in the periods between attacks, their subclinical inflammation continues. The aim of the present study was to determine the NAFLD frequency in FMF patients and to evaluate their MetS, IR and lipid profiles. METHODS: The study included 54 FMF patients and 54 control subjects. The clinical and demographic characteristics of the subjects were recorded, and the patients' Pras disease severity score was calculated. IR was determined using the homeostasis model assessment (HOMA) index. MetS was diagnosed using the revised National Cholesterol Education Program Adult Treatment Panel III criteria (NCEP ATP III). Hepatic ultrasonography was used to diagnose NAFLD. RESULTS: NAFLD was observed in 15 FMF patients (27.8%) and 14 controls (25.9%). The difference between the groups was not significant (p=0.828). Similarly, no significant difference was found between the two groups for MetS frequency and HOMA index levels. Fasting plasma glucose was significantly higher in FMF patients, whereas differences between the two groups were not significant for lipid levels and other parameters. When FMF patients with and without NAFLD were compared, no significant difference was found in Pras disease severity score, duration of the disease and daily colchicine dose. CONCLUSION: The present study showed that NAFLD frequency was not increased in FMF patients, and that patients' MetS frequency, IR and lipid profiles were not different from control subjects.

Familial Mediterranean fever and atherosclerosis in childhood and adolescence.

Familial Mediterranean fever is a chronic inflammatory disease characterized by periodic and self-limited episodes of fever and aseptic polyserositis. Although colchicine treatment has altered the course of the disease, it is believed that subclinical inflammation is still present, leading to endothelial dysfunction and atherosclerosis in the course of time. In this review, following the published recommendations, we queried online databases such as MEDLINE Pubmed, Scopus, and Web of science for peer-reviewed studies and reviews written in English language, using the following keywords: familial Mediterranean fever, children, endothelial dysfunction, atherosclerosis, cardiovascular disease. The objective of this review is to highlight the correlation between familial Mediterranean fever and atherosclerosis, and moreover to describe new serum inflammatory markers and non-invasive methods of endothelial dysfunction, to detect the atherosclerosis process early starting from childhood.

Fecal calprotectin in children with familial Mediterranean fever in the attack-free period.

BACKGROUND: Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent episodes of fever and serosal inflammation. The aim of this study was to evaluate fecal calprotectin (FC) in children with FMF during the non-attack period. METHODS: A retrospective evaluation was made of the data of a total 66 patients diagnosed with FMF in an attack-free period and without amyloidosis or inflammatory bowel disease (IBD). FC level in the FMF patients was compared with that in the patients with IBD and healthy control subjects. RESULTS: The FMF patients consisted of 37 boys (56.1%) with a mean age of 10.1 ± 3.9 years. Mean FC was 192.5 µg/g (range, 19.5-800 µg/g) in the FMF group, 597.9 µg/g (range, 180-800 µg/g) in the IBD group, and 43.8 µg/g (range, 19.5-144 µg/g) in the control group. The FC level in the children with FMF was higher than in the control group (P < 0.001), and the FC level of the IBD patients was higher than both the FMF and the control groups (P = 0.020, P < 0.001, respectively). CONCLUSIONS: FC was higher in FMF patients compared with healthy children even in the absence of IBD/amyloidosis. Even though colonoscopy is the gold standard in identifying intestinal inflammation in FMF patients, FC, a non-invasive and inexpensive method, can be used for screening. The presence of subclinical intestinal inflammation was also quantitatively identified in children with FMF.

Evaluation of the effects of miRNAs in familial Mediterranean fever.

Familial Mediterranean fever (FMF) is an inherited autoinflammatory disorder that can result in attacks with accompanying recurrent episodes of fever, serositis, and skin rash. MiRNAs are demonstrated to be associated with a number of other diseases; however, no comprehensive study has revealed its association with FMF disease. The aim is to investigate the role of microRNAs in FMF. We included 51 patients with genetically diagnosed FMF who had clinical symptoms and 49 healthy volunteers. Fifteen miRNAs that were found to be associated with autoinflammatory diseases and have a part in immune response were evaluated. The expression levels of 11 miRNAs (miR-125a, miR-132, miR-146a, miR-155, miR-15a, miR-16, miR-181a, miR-21, miR-223, miR-26a, and miR-34a) in the patient group were significantly low, compared with the control group (p < 0.05). The patient group was analyzed and compared within itself, and the expression levels of 5 miRNAs (miR-132, miR-15a, miR-181a, miR-23b, miR-26a) in the patients who took colchicine seemed to have increased and levels of 5 miRNAs (miR-146a, miR-15a, miR-16, miR-26a, miR-34a) in the patients who took colchicine were significantly lower (p < 0.05). Furthermore, the attack patients were compared with the control group, and their expression levels of 4 miRNAs (miR-132, miR-15a, miR-21, miR-34a) were significantly lower (p < 0.05). Levels of 9 miRNAs (miR-132, miR-146a, miR-15a, miR-16, miR-181a, miR-21, miR-223, miR-26a, miR-34a) in non-attack patients decreased significantly (p < 0.05). Our study demonstrates that miRNAs could be effective in the pathogenesis of FMF.

Potential role of pyrin, the protein mutated in familial Mediterranean fever, during inflammatory cell migration.

Familial Mediterranean fever (FMF), the most common of the systemic autoinflammatory disorders, is caused by mutations in the MEFV (Mediterranean Fever) gene, which encodes the protein pyrin. Neutrophils, one of the major components during inflammation, are the main cell type that expresses pyrin. In response to an inflammatory stimulus, neutrophils migration to their main active site. To date, several pyrin-interacting proteins have been demonstrated to co-localise with the cytoskeletal protein actin, which is important in the process of neutrophil migration and raises the question of whether pyrin plays a role in the actin cytoskeletal network during inflammatory cell migration. In this study, we examined the possible role of pyrin during inflammatory cell migration in neutrophils. We generated a cell migration assay with neutrophils and primary neutrophils from patients. We also knocked down pyrin expression using siRNA and then performed cell migration assay. We showed co-localisation of pyrin and F-actin at the leading edge during inflammatory cell migration. In pyrin knocked down cells, we identified a significant decrease in neutrophil migration. In addition, we demonstrated a dramatic increase in migration in the neutrophils of FMF patients compared with a healthy control group. These data together provide new insight into the cellular function of pyrin and demonstrate an important link between pyrin and polymerising actin in the process of inflammatory cell migration.

Role of fecal calprotectin in the assessment of intestinal inflammation in children with familial Mediterranean fever.

AIM: Familial Mediterranean fever (FMF) is the most common auto-inflammatory disease with recurrent fever and serositis episodes. In recent years, some cases with FMF were reported with gastrointestinal involvement without amyloidosis, vasculitis and inflammatory bowel disease (IBD). It is not yet known whether gastrointestinal involvement is a part of the disease or not. The aim of this study is to investigate the frequency of intestinal inflammation by using a noninvasive method, fecal calprotectin measurement, in pediatric FMF patients. METHOD: Sixty-five FMF patients, 30 healthy controls and 11 patients with acute ulcerative colitis were included in the study. A standard survey inquiring gastrointestinal and other clinical symptoms was completed. The medications, MEFV mutations, whole blood count and C-reactive protein levels were recorded. Fecal calprotectin was studied with the enzyme-linked immunosorbent assay method from the feces samples of the all subjects. RESULTS: None of the FMF patients had clinical signs of IBD. Fecal calprotectin levels of the FMF patients were found to be significantly higher than the healthy controls (174.8 ± 150.8 vs 52.9 ± 36.5, p < 0.001). Fecal calprotectin levels of the ulcerative colitis patients were significantly higher than the FMF patients (523.5 ± 183 vs 174.8 ± 150.8, p = 0.001). There was a correlation between fecal calprotectin levels and neutrophil/lymphocyte ratio (r = 0.324, p = 0.009). CONCLUSION: Our results supported subclinical intestinal inflammation in pediatric FMF patients. Further studies are needed to clarify the reason for intestinal inflammation in FMF patients.

The patient journey to diagnosis and treatment of autoinflammatory diseases.

BACKGROUND: Limited data are available on the experiences of patients with autoinflammatory diseases (AIDs) and their families along the path to diagnosis and treatment. We sought to describe these experiences in patients with AIDs including tumor necrosis factor receptor-associated periodic syndrome (TRAPS), mevalonate kinase deficiency/hyperimmunoglobulin D syndrome (MKD/HIDS), and familial Mediterranean fever (FMF). METHODS: Ninety-minute, semi-structured qualitative interviews and 5-day written/video diaries were used to gather information on the experiences of patients with AIDs and their families. RESULTS: Twelve families of patients from the US (TRAPS [n = 4], MKD/HIDS [n = 5], FMF [n = 5]) participated in this study from August to November 2015. The study included two families with multiple afflicted siblings. Patients' ages ranged from 1 to 28 years. Most parents reported realizing that something was seriously wrong with their child after medical emergencies and/or hospitalizations, which initiated the difficult path to diagnosis. For most, the process included multiple specialist visits, extensive and repeated testing, and many misdiagnoses. Over time, 92% of parents reported losing confidence in the healthcare system's ability to find an answer to their child's symptoms, while they also struggled with unsupportive school personnel and dismissive friends and relatives. Patients and their parents reported holding on to memories of "what life was like" before the onset of symptoms and mourning their subsequent loss of "normalcy." Even after diagnosis, patients and parents continued to feel uncertain about what to expect in the future. CONCLUSIONS: All families emphasized the need for efficient early diagnosis of AIDs. Initiatives that improve the speed and accuracy of diagnosis, provide more comprehensive patient education, and support patients and families through the illness have the potential to significantly improve the quality of life of patients with AIDs and their families. Healthcare providers should be aware of the impact of the long diagnostic journey on families and work to create an environment of trust and collaboration in the face of a difficult and prolonged diagnostic process.

GSDMD is critical for autoinflammatory pathology in a mouse model of Familial Mediterranean Fever.

Pyroptosis is an inflammasome-induced lytic cell death mode, the physiological role of which in chronic inflammatory diseases is unknown. Familial Mediterranean Fever (FMF) is the most common monogenic autoinflammatory disease worldwide, affecting an estimated 150,000 patients. The disease is caused by missense mutations in Mefv that activate the Pyrin inflammasome, but the pathophysiologic mechanisms driving autoinflammation in FMF are incompletely understood. Here, we show that Clostridium difficile infection of FMF knock-in macrophages that express a chimeric FMF-associated MefvV726A Pyrin elicited pyroptosis and gasdermin D (GSDMD)-mediated interleukin (IL)-1ß secretion. Importantly, in vivo GSDMD deletion abolished spontaneous autoinflammatory disease. GSDMD-deficient FMF knock-in mice were fully protected from the runted growth, anemia, systemic inflammatory cytokine production, neutrophilia, and tissue damage that characterize this autoinflammatory disease model. Overall, this work identifies pyroptosis as a critical mechanism of IL-1ß-dependent autoinflammation in FMF and highlights GSDMD inhibition as a potential antiinflammatory strategy in inflammasome-driven diseases.