Genetic variation in the familial Mediterranean fever gene (MEFV) and risk for Crohn's disease and ulcerative colitis

High frequency of MEFV disease-causing variants in children with very-early-onset inflammatory bowel disease

BACKGROUND

Biological similarities between inflammatory bowel disease (IBD) and familial Mediterranean fever (FMF) have been described in humans and animal models suggesting a possible common genetic basis. FMF is caused by variants in the MEFV gene which encodes pyrin, an immune regulator. This study aimed to investigate the carrier rate of disease-causing MEFV variants in children of different ethnicities diagnosed with very-early-onset IBD (VEO-IBD).

METHODS

The study included 23 children diagnosed with VEO-IBD who had undergone whole exome sequencing. The exomes were evaluated for MEFV monoallelic and biallelic disease-causing variants and compared to exome sequencing data of 250 probands with suspected monogenic diseases other than IBD.

RESULTS

Of the 23 children diagnosed with VEO-IBD, 12 (52%) were carriers of at least one MEFV disease-causing variant, which was threefold higher than in individuals without IBD. The most frequent variants identified were p.M694V and p.E148Q (42% each). The allelic frequency of MEFV variants was found to be higher across the VEO-IBD group in 13 of 14 ethnicities compared to the control group.

CONCLUSION

The study suggests that disease-causing variants in the MEFV gene should be sought in cases of VEO-IBD. However, the clinical importance of this finding is yet to be defined.

IMPACT

There are biological similarities between inflammatory bowel disease and familial Mediterranean fever, suggesting a possible genetic relationship. Children less than 6 years old clinically diagnosed with inflammatory bowel disease have a threefold higher rate of disease-causing variants in the MEFV gene than controls. Monogenic testing in children with very-early-onset inflammatory bowel disease should include a search for MEFV variants.

Familial Mediterranean fever with colonic lesions: A case report

A 26-year-old man with a history of ulcerative colitis treatment presented to our clinic with abdominal pain and fever. He had a history of bloody stools and abdominal pain at 19 years of age. A thorough examination by a medical practitioner, including lower gastrointestinal endoscopy, resulted in the diagnosis of ulcerative colitis. After induction of remission with prednisolone (PSL), the patient was treated with 5-aminosalicylate. One year ago in September, his symptoms flared up again, and he was administered 30 mg/day of PSL until November of the same year. However, he was transferred to another hospital and referred to his previous doctor. During the follow-up in December of the same year, flare-ups of abdominal pain and diarrhea were reported. Upon review of the patient's medical history, familial Mediterranean fever was suspected because the patient had periodic fevers ≥38°C and symptoms that persisted even after oral steroid administration and were sometimes accompanied by joint pain. However, he was transferred again, and PSL was administered once more. The patient was referred to our hospital for further treatment. At the time of arrival, his symptoms did not improve with 40 mg/day of PSL, and endoscopy and computed tomography revealed thickening of the colon, with no abnormality in the small intestine. Suspecting familial Mediterranean fever-associated enteritis, the patient was administered colchicine, resulting in an improvement in symptoms. Furthermore, an examination of the MEFV gene showed a mutation in Exon5 (S503C), and atypical familial Mediterranean fever was diagnosed. Endoscopy after colchicine treatment revealed that the ulcers improved remarkably.

Familial Mediterranean fever in Armenian children with inflammatory bowel disease

Inflammatory bowel disease (IBD) and familial Mediterranean fever (FMF) are inflammatory diseases with complex interactions among genetic, immune, and environmental factors. FMF is a monogenic autoinflammatory disease, characterized by recurrent febrile attacks and polyserositis, and is manifested mainly in childhood. FMF is widespread in Armenia. There are reports on the concurrent occurrence of FMF and IBD. MEFV gene mutations may have a disease-modifying effect on IBD. We have investigated the frequency of MEFV mutations and FMF in Armenian children with IBD and their influence on the clinical course. A total of 69 untreated IBD patients under 18 years of age were enrolled: 52.1% (36) had ulcerative colitis (UC), 21.7% (15) had Crohn's disease (CD), and 26.0% (18) had unclassified colitis (IBD-U). The frequency of FMF among them was 36.2% (25/69), and MEFV mutations were identified in 53.6% (37/69). The highest rate of MEFV mutations and FMF was in UC patients (61.1% and 41.6% respectively). In all, 56.7% (21/37) of IBD patients with MEFV mutations had M694V mutated alleles, mainly in compound heterozygous and heterozygous states. There were no associations in the group of IBD patients with coexisting FMF (25), either between any MEFV mutation and type of IBD or coexistence of FMF. Overall, 36.0% (9/25) of them developed VEO IBD and carried mainly the M694V mutation. We concluded that the carrier frequency of MEFV mutations among Armenian pediatric IBD patients was rather high (53.6%), especially for UC. It was suggested that the MEFV gene is not necessarily a susceptibility gene but most likely modifies the course of IBD. MEFV genetic testing was recommended for Armenian pediatric IBD patients, especially for VEO UC and IBD-U, atypical IBD course, or resistance to the conventional treatment. They should also be asked for isolated febrile attacks, recurrent arthritis, and family history, even in the absence of FMF typical symptoms, to rule out FMF and its complications.

The Influence of Coexisting Familial Mediterranean Fever on Crohn's Disease: Data From an FMF Endemic Area

GOAL

The goal of this study was to evaluate the impact of coexisting familial Mediterranean fever (FMF) on Crohn's disease (CD) patients' phenotype and disease course in an endemic region for FMF.

BACKGROUND

CD and FMF are inflammatory diseases characterized by recurrent abdominal pain and fever attacks. The impact of coexisting FMF on CD patients' phenotype and disease course is currently unknown.

MATERIALS AND METHODS

We reviewed the medical records of 210 adult CD patients who were regularly followed up at a tertiary gastroenterology clinic between November 2006 and April 2018. The patients were divided into FMF positive (CD-FMF) and FMF negative (CD-control) groups. The severity of CD was assessed by the rate of hospitalization because of CD, the need for biological therapy, and whether surgery was performed for CD.

RESULTS

Eight (3.8%) of 210 CD patients have concomitant FMF, which is 35 to 40 times higher than expected in an endemic region for FMF. Baseline demographic parameters, location/behavior of the CD, and initial therapeutic regimens were similar between the 2 groups. The prevalence of peripheral arthritis was significantly higher in CD-FMF group (37.5% vs. 10.4%, respectively, P =0.04). A significantly greater proportion of the CD-FMF patients had received biological therapy (50% vs. 11.9%; P =0.012). Steroid dependence and CD-related hospitalization rates in the CD-FMF group were relatively higher but were not statistically significant (37.5% vs. 15.3 and 62.5% vs. 41.1%).

CONCLUSIONS

Our findings indicate that the disease course of CD tends to be more severe in patients with coexisting FMF.

Vasculitis and familial Mediterranean fever: Description of 22 French adults from the juvenile inflammatory rheumatism cohort

Objective

The frequency of vasculitis may be increased in patients with Familial Mediterranean Fever (FMF), according to several studies. Our aim was to assess the characteristics of French adult patients with both diseases.

Methods

Patients with vasculitis were selected from patients followed for FMF in the French JIR-cohort.

Results

Twenty-two patients were included [polyarteritis nodosa (PAN) n = 10, IgA vasculitis n = 8, unclassified vasculitis n = 2, granulomatosis with polyangiitis n = 1, and microscopic polyangiitis n = 1]. Pathogenic mutations in exon 10 were found in all 21 patients (96%) for which MEFV testing results were available, and 18 (82%) had two pathogenic mutations. Histology showed vasculitis in 59% of patients. Most patients with FMF-associated PAN were HBV-negative and had an inactive FMF before PAN onset, and 40% had a peri-renal or central nervous system bleeding. Most patients with FMF-associated IgA vasculitis had an active FMF before vasculitis onset, and 25% had digestive bleeding. Both patients with unclassified vasculitis had ischemic and/or hemorrhagic complications.

Conclusion

This study confirms the predominance of PAN and IgA vasculitis in patients with FMF and the high frequency of bleeding in FMF-associated PAN. FMF should be considered in case of persistent symptoms and/or inflammatory syndrome despite vasculitis treatment in Mediterranean patients.

MEFV and NLRP3 Inflammasome Expression Is Attributed to Immature Macrophages and Correlates with Serum Inflammatory Proteins in Crohn´s Disease Patients

Inflammasomes are intracellular protein complexes whose activation results in proinflammatory cytokines. Inflammasomes are implicated in Crohn´s disease (CD) pathogenesis, yet the contribution of inflammasomes in intestinal epithelial cells (IECs) versus lamina propria (LP) macrophages is poorly understood. Whether inflammasome expression in intestinal tissue reflects the serum inflammatory protein profile of patients is also not known. We aimed to determine the intestinal cell types where inflammasome expression is increased in CD and if they correlate with the serum protein profile. RT-PCR and NanoString nCounter technology were used to characterize inflammasome gene expression in CD patients and controls. The mucosa, LP and IEC cell fractions and FACS-sorted cells were analyzed. Proximity extension assay with a 92-protein panel was used to determine the serum inflammatory protein profile. Compositional analysis was used to correlate ileum inflammasome gene expression with intestinal mononuclear phagocyte populations. We show that NLRP3 and MEFV inflammasome sensors and downstream effector expression including IL-1β are increased in inflamed mucosa of IBD patients and correlate with disease activity. Inflammasome gene expression increased with the abundance of immature intestinal macrophages, and increased IL-1β released by CD LP cells correlated with immature macrophage frequency. Inflammasome gene expression was also increased in circulating monocytes, the precursors of immature intestinal macrophages. Finally, the serum inflammatory profile of CD patients correlates with ileal expression of genes related to NLRP3 and MEFV inflammasomes. Overall, we show that MEFV and NLRP3 inflammasome expression in CD intestine is attributed to the accumulation of immature macrophages and correlates with serum inflammatory proteins.

Evaluation of the Clinical Effects and Frequency of MEFV Gene Mutation in Patients with Inflammatory Bowel Disease

Background

The clinical and pathological features of inflammatory bowel disease (IBD) and Familial Mediterranean Fever (FMF) are similar.

Objective

Here, the frequency of Mediterranean Fever (MEFV) gene mutation and its effect on the outcome of IBD were evaluated.

Methods

DNA sequence analysis detected the variants on the MEFV gene in patients with IBD. The relationship between mutations and the need for steroids, immunomodulators, biologics, and surgery was assessed.

Results

We evaluated 100 patients with IBD (55 with ulcerative colitis (UC) and 45 with Crohn's disease (CD)) and 60 healthy individuals as controls. The frequency of MEFV gene mutation was 26.7% (n = 12) and 14.5% (n = 8) for UC and CD, respectively. No relationship was found between MEFV gene mutation and the need for steroids, immunomodulators, and biologics (p = 0.446; p = 0.708; p > 0.999, resp.); however, in UC, the need for surgery in those with mutation (p = 0.018) and E148Q mutation alone was significant (p = 0.037).

Conclusion

The rate of MEFV gene mutations was high in patients with UC who required surgery. These patients have frequent and severe attacks, indicating that the mutations are related to disease severity. MEFV mutation as a modifier factor of IBD should be considered.

Real-Life Indications of Interleukin-1 Blocking Agents in Hereditary Recurrent Fevers: Data From the JIRcohort and a Literature Review

Background

Interleukin (IL)-1 inhibitors represent the main treatment in patients with colchicine-resistant/intolerant familial Mediterranean fever (crFMF), mevalonate kinase deficiency (MKD), and tumor necrosis factor receptor-associated periodic syndrome (TRAPS). However, the reasons for the use of IL-1 inhibitors in these diseases are still not completely clarified.

Objective

Identify real-life situations that led to initiating anakinra or canakinumab treatment in hereditary recurrent fevers (HRFs), combining data from an international registry and an up-to-date literature review.

Patients and Methods

Data were extracted from the JIRcohort, in which clinical information (demographic data, treatment, disease activity, and quality of life) on patients with FMF, MKD, and TRAPS was retrospectively collected. A literature search was conducted using Medline, EMBASE, and Cochrane databases.

Results

Complete data of 93 patients with HRF (53.8% FMF, 31.2% MKD, and 15.1% TRAPS) were analyzed. Data from both the registry and the literature review confirmed that the main reasons for use of IL-1 blockers were the following: failure of previous treatment (n = 57, 61.3% and n = 964, 75.3%, respectively), persistence of disease activity with frequent attacks (n = 44, 47.3% and n = 1,023, 79.9%) and/or uncontrolled inflammatory syndrome (n = 46, 49.5% and n = 398, 31.1%), severe disease complication or associated comorbidities (n = 38, 40.9% and n = 390, 30.4%), and worsening of patients' quality of life (n = 36, 38.7% and n = 100, 7,8%). No reasons were specified for 12 (16.4%) JIRcohort patients and 154 (12%) patients in the literature.

Conclusion

In the absence of standardized indications for IL-1 inhibitors in crFMF, MKD, and TRAPS, these results could serve as a basis for developing a treat-to-target strategy that would help clinicians codify the therapeutic escalation with IL-1 inhibitors.

Ancestral Haplotype Mapping for GWAS and Detection of Signatures of Selection in Admixed Dairy Cattle of Kenya

Understanding the genetic structure of adaptation and productivity in challenging environments is necessary for designing breeding programs that suit such conditions. Crossbred dairy cattle in East Africa resulting from over 60 years of crossing exotic dairy breeds with indigenous cattle plus inter se matings form a highly variable admixed population. This population has been subject to natural selection in response to environmental stresses, such as harsh climate, low-quality feeds, poor management, and strong disease challenge. Here, we combine two complementary sets of analyses, genome-wide association (GWA) and signatures of selection (SoS), to identify genomic regions that contribute to variation in milk yield and/or contribute to adaptation in admixed dairy cattle of Kenya. Our GWA separates SNP effects due to ancestral origin of alleles from effects due to within-population linkage disequilibrium. The results indicate that many genomic regions contributed to the high milk production potential of modern dairy breeds with no region having an exceptional effect. For SoS, we used two haplotype-based tests to compare haplotype length variation within admixed and between admixed and East African Shorthorn Zebu cattle populations. The integrated haplotype score (iHS) analysis identified 16 candidate regions for positive selection in the admixed cattle while the between population Rsb test detected 24 divergently selected regions in the admixed cattle compared to East African Shorthorn Zebu. We compare the results from GWA and SoS in an attempt to validate the most significant SoS results. Only four candidate regions for SoS intersect with GWA regions using a low stringency test. The identified SoS candidate regions harbored genes in several enriched annotation clusters and overlapped with previously found QTLs and associations for different traits in cattle. If validated, the GWA and SoS results indicate potential for SNP-based genomic selection for genetic improvement of smallholder crossbred cattle.

Genetic aspects of idiopathic paediatric uveitis and juvenile idiopathic arthritis associated uveitis in Chinese Han

Background

Idiopathic paediatric uveitis (IPU) and juvenile idiopathic arthritis associated uveitis (JIA-U) are the two most common entities in paediatric uveitis. This study addressed the possible association of IPU and JIA-U with genes that had been shown earlier to be associated with juvenile idiopathic arthritis.

Methods

We carried out a case-control association study involving 286 IPU, 134 JIA-U patients and 743 healthy individuals. A total of 84 candidate single nucleotide polymorphisms (SNPs) in 60 genes were selected for this study. The MassARRAY platform and iPLEX Gold Genotyping Assay was used to genotype 83 candidate SNPs and the remaining SNP (rs27293) was analysed using the TaqMan SNP Genotyping Assay.

Results

No evidence was found for an association of the candidate polymorphisms tested with IPU. Six SNPs (PRM1/rs11074967, JAZF1/rs73300638, IRF5/rs2004640, MEFV/rs224217, PSMA3/rs2348071 and PTPN2/rs7234029) showed an association with JIA-U (p<1.0×10⁻²).

Conclusion

Our findings showed associations of six SNPs (PRM1/rs11074967, JAZF1/rs73300638, IRF5/rs2004640, MEFV/rs224217, PSMA3/rs2348071 and PTPN2/rs7234029) with JIA-U. No association was detected between the 84 tested SNPs and IPU.

The Role of Familial Mediterranean Fever Gene Mutation in Treatment of Infantile Colitis With Resistant Perianal Fistula

Symptoms of infantile inflammatory bowel disease (I-IBD) can be life-threatening and associated with poor prognosis. The presence of Mediterranean fever (MEFV) gene mutations play an important role in treatment of I-IBD. In this article, we describe a case of I-IBD with a resistant fistula, in which remission occurred following colchicine therapy. The patient was a six-month-girl with complaints of bloody diarrhea and a perianal abscess of three months duration. Laboratory tests revealed elevated inflammatory parameters, hypoalbuminemia, and anemia. Results of repeated viral, bacterial and parasitic analyses were negative. Endoscopic and histopathological examinations confirmed a diagnosis of I-IBD. Although diarrhea episodes decreased following intensive conventional treatment with immunosuppressive therapy and anti-tumor necrosis factor, the perianal abscess and fistula did not resolve. Molecular genetic analysis to identify causes of infantile disease revealed the MEFV gene mutation. Thus, colchicine was added to the treatment regimen. Following treatment with colchicine, defecation returned to normal, and the fistula resolved. The MEFV gene mutation should be investigated in children with infantile colitis and resistant fistulas, particularly in Mediterranean countries. In patients with infantile colitis who have the MEFV gene mutation, colchicine treatment may be an alternative to intensive immunosuppressive therapy.

Bile acid analogues are activators of pyrin inflammasome

Bile acids are critical metabolites in the gastrointestinal tract and contribute to maintaining intestinal immune homeostasis through cross-talk with the gut microbiota. The conversion of bile acids by the gut microbiome is now recognized as a factor affecting both host metabolism and immune responses, but its physiological roles remain unclear. We conducted a screen for microbiome metabolites that would function as inflammasome activators and herein report the identification of 12-oxo-lithocholic acid (BAA485), a potential microbiome-derived bile acid metabolite. We demonstrate that the more potent analogue 11-oxo-12S-hydroxylithocholic acid methyl ester (BAA473) can induce secretion of interleukin-18 (IL-18) through activation of the inflammasome in both myeloid and intestinal epithelial cells. Using a genome-wide CRISPR screen with compound induced pyroptosis in THP-1 cells, we identified that inflammasome activation by BAA473 is pyrin-dependent (MEFV). To our knowledge, the bile acid analogues BAA485 and BAA473 are the first small molecule activators of the pyrin inflammasome. We surmise that pyrin inflammasome activation through microbiota-modified bile acid metabolites such as BAA473 and BAA485 plays a role in gut microbiota regulated intestinal immune response. The discovery of these two bioactive compounds may help to further unveil the importance of pyrin in gut homeostasis and autoimmune diseases.

Familial Mediterranean Fever with Small Bowel Stenosis

A 37-year-old man developed abdominal pain and the frequency of severe abdominal pain steadily increased to once a month. He was therefore admitted to our hospital. Abdominal CT showed bowel obstruction. It revealed transient stenosis in the small intestine. There were no symptoms such as fever or weight loss, it seemed unlikely that the patient had inflammatory bowel disease. Considering the history of recurrent abdominal pain, Familial Mediterranean Fever (FMF) was considered. As a result, a genetic analysis revealed mutations in exons 3 and 8 of the MEFV gene. We herein report the first known case of FMF with transient small bowel stenosis in Japan.

Recent Advance in Very Early Onset Inflammatory Bowel Disease

Recent studies on pediatric inflammatory bowel disease (IBD) have revealed that early-onset IBD has distinct phenotypic differences compared with adult-onset IBD. In particular, very early-onset IBD (VEO-IBD) differs in many aspects, including the disease type, location of the lesions, disease behavior, and genetically attributable risks. Several genetic defects that disturb intestinal epithelial barrier function or affect immune function have been noted in these patients from the young age groups. In incidence of pediatric IBD in Korea has been increasing since the early 2000s. Neonatal or infantile-onset IBD develops in less than 1% of pediatric patients. Children with "neonatal IBD" or "infantile-onset IBD" have higher rates of affected first-degree relatives, severe disease course, and a high rate of resistance to immunosuppressive treatment. The suspicion of a monogenic cause of VEO-IBD was first confirmed by the discovery of mutations in the genes encoding the interleukin 10 (IL-10) receptors that cause impaired IL-10 signaling. Patients with such mutations typically presented with perianal fistulae, shows a poor response to medical management, and require early surgical interventions in the first year of life. To date, 60 monogenic defects have been identified in children with IBD-like phenotypes. The majority of monogenic defects presents before 6 years of age, and many present before 1 year of age. Next generation sequencing could become an important diagnostic tool in children with suspected genetic defects especially in children with VEO-IBD with severe disease phenotypes. VEO-IBD is a phenotypically and genetically distinct disease entity from adult-onset or older pediatric IBD.

Recent advance in very early-onset inflammatory bowel disease

Recent studies on pediatric inflammatory bowel disease (IBD) have revealed that early-onset IBD has distinct phenotypic differences compared with adult-onset IBD. In particular, very early-onset IBD (VEO-IBD) differs in many aspects, including the disease type, location of the lesions, disease behavior, and genetically attributable risks. Neonatal or infantile-onset IBD develops in less than 1% of pediatric patients. Children with infantile-onset IBD have high rates of affected first-degree relatives and severe disease course. The suspicion of a monogenic cause of VEO-IBD was first confirmed by the discovery of mutations in the genes encoding the interleukin 10 (IL-10) receptors that cause impaired IL-10 signaling. Patients with such mutations typically presented with perianal fistulae, shows a poor response to medical management, and require early surgical interventions in the first year of life. To date, 60 monogenic defects have been identified in children with IBD-like phenotypes. The majority of monogenic defects presents before 6 years of age, and many present before 1 year of age. Next generation sequencing could become an important diagnostic tool in children with suspected genetic defects especially in children with VEO-IBD with severe disease phenotypes. VEO-IBD is a phenotypically and genetically distinct disease entity from adult-onset or older pediatric IBD.

Lack of clear and univocal genotype-phenotype correlation in familial Mediterranean fever patients: A systematic review

Familial Mediterranean fever (FMF) is the most common autosomal recessive autoinflammatory disease. To date, following the isolation of more than 280 MEFV sequence variants, the genotype-phenotype correlation in FMF patients has been intensively investigated; however, an univocal and clear consensus has not been yet reached. Thus, the aim of this systematic review was to analyze the available literature findings in order to provide to scientific community an indirect estimation of the impact of genetic factors on the phenotypic variability of FMF. This systematic review has been conducted according to the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines. The p.M694V mutation was reported to have a relatively severe clinical course, similarly, patients homozygous for M694I and M680I, or carrying a combination of both at codons 694 and 680, have a severe disease. Also, patients homozygous for M694V and V726A variants experienced more severe clinical picture. Conversely, heterozygous p.V726A and p.E148Q genotypes have been correlated with a milder disease course. At present, doubts remain on the potential pathogenic role of E148Q variant. The heterogenity in clinical FMF manifestations reflects the changes occuring in repertoire of mutations. We believe that clinical criteria and gene tests, enhancing each other, could better support the diagnosis of FMF.

[Familial Mediterranean fever]

Familial Mediterranean Fever (FMF) is the most frequent monogenic auto-inflammatory disease. FMF is an autosomal recessive disease, which affects populations from Mediterranean origin and is associated with MEFV gene mutations encoding for the protein pyrin. Pyrin activation enhances the secretion of interleukin 1 by myelo-monocytic cells. Main features of the disease are acute attacks of serositis mainly located on the abdomen, less frequently on chest and joints, accompanied by fever and biological inflammatory markers elevation. Usually attacks last 1 to 3 days and spontaneously stop. A daily oral colchicine intake of 1 to 2mg/day is able to prevent attack's occurrence, frequency, intensity and duration among most patients. Colchicine is also able to prevent the development of inflammatory amyloidosis, the most severe complication of FMF. This state of the art article will focus on the diagnosis of FMF, the treatment and an update on the pathophysiology including the recent described dominant form of MEFV-associated new auto-inflammatory diseases.

Pyrin Inflammasome Regulates Tight Junction Integrity to Restrict Colitis and Tumorigenesis

BACKGROUND & AIMS

Inflammatory bowel diseases (IBD) increase risk for colorectal cancer. Mutations in the Mediterranean fever gene (MEFV or pyrin) are associated with hereditary autoinflammatory disease and severe IBD. Expression of MEFV, a sensor protein that the initiates assembly of the inflammasome complex, is increased in colon biopsies from patients with IBD. We investigated the role of pyrin in intestinal homeostasis in mice.

METHODS

Mefv-/- mice and C57/BL6 mice (controls) were given azoxymethane followed by multiple rounds of dextran sodium sulfate (DSS) to induce colitis and tumorigenesis. In some experiments, Mefv-/- mice were given injections of recombinant interleukin 18 (rIL18) or saline (control) during DSS administration. Colon tissues were collected at different time points during colitis development and analyzed by histology, immunohistochemistry, immunoblots, or ELISAs (to measure cytokines). Spleen and mesenteric lymph node were collected, processed, and analyzed by flow cytometry. Colon epithelial permeability was measured in mice with colitis by gavage of fluorescent dextran and quantification of serum levels.

RESULTS

MEFV was expressed in colons of control mice and expression increased during chronic and acute inflammation; high levels were detected in colon tumor and adjacent non-tumor tissues. Mefv-/- mice developed more severe colitis than control mice, with a greater extent of epithelial hyperplasia and a larger tumor burden. Levels of inflammatory cytokines (IL6) and chemokines were significantly higher in colons of Mefv-/- mice than control mice following colitis induction, whereas the level IL18, which depends on the inflammasome for maturation and release, was significantly lower in colons of Mefv-/- mice. Mefv-/- mice had increased epithelial permeability following administration of DSS than control mice, and loss of the tight junction proteins occludin and claudin-2 from intercellular junctions. STAT3 was activated (phosphorylated) in inflamed colon tissues from Mefv-/-, which also had increased expression of stem cell markers (OLFM4, BMI1, and MSI1) compared with colons from control mice. Administration of rIL18 to Mefv-/- mice reduced epithelial permeability, intestinal inflammation, the severity of colitis, and colon tumorigenesis.

CONCLUSIONS

In studies with DSS-induced colitis, we found that pyrin (MEFV) is required for inflammasome activation and IL18 maturation, which promote intestinal barrier integrity and prevent colon inflammation and tumorigenesis. Strategies to increase activity of MEFV or IL18 might be developed for the treatment of IBD and prevention of colitis-associated tumorigenesis.

Inflammatory Diseases of the Gut

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are chronic inflammatory disorders of the gastrointestinal tract whose prevalence has been dramatically increasing over the past decade. New studies have shown that IBD is the second most common chronic inflammatory disease worldwide after rheumatoid arthritis, affecting millions of people mainly in industrialized countries. Symptoms of IBD include frequent bloody diarrhea, abdominal cramping, anorexia, abdominal distension, and emesis. Although the exact etiology is unknown, it has been postulated that immunological, microbial, environmental, nutritional, and genetic factors contribute to the pathogenesis and severity of IBD. Today, no treatment has consistently been shown to be successful in treating IBD. This review summarizes current research on the epidemiology, etiology, pathophysiology, and existing treatment approaches, including pharmaceutical and nutritional options for IBD.

Exaggerated IL-15 and Altered Expression of foxp3+ Cell-Derived Cytokines Contribute to Enhanced Colitis in Nlrp3-/- Mice

The pathogenesis of Crohn's disease (CD) involves defects in the innate immune system, impairing responses to microbes. Studies have revealed that mutations NLRP3 are associated with CD. We reported previously that Nlrp3−/− mice were more susceptible to colitis and exhibited reduced colonic IL-10 expression. In the current study, we sought to determine how the loss of NLRP3 might be altering the function of regulatory T cells, a major source of IL-10. Colitis was induced in wild-type (WT) and Nlrp3−/− mice by treatment with dextran sulphate sodium (DSS). Lamina propria (LP) cells were assessed by flow cytometry and cytokine expression was assessed. DSS-treated Nlrp3−/− mice exhibited increased numbers of colonic foxp3+ T cells that expressed significantly lower levels of IL-10 but increased IL-17. This was associated with increased expression of colonic IL-15 and increased surface expression of IL-15 on LP dendritic cells. Neutralizing IL-15 in Nlrp3−/− mice attenuated the severity of colitis, decreased the number of colonic foxp3+ cells, and reduced the colonic expression of IL-12p40 and IL-17. These data suggest that the NLRP3 inflammasome can regulate intestinal inflammation through noncanonical mechanisms, providing additional insight as to how NLRP3 variants may contribute to the pathogenesis of CD.

Two Genetic Variations in the IRF8 region are associated with Behçet's disease in Han Chinese

Several modulatory factors in the TLR signaling pathway including IRF3, IRF7, IRF8, TRIM20, MYD88 and NF-κB1 have been associated with autoimmune disease. In this study, we investigated the association of 13 SNPs for these genes with Behçet’s disease (BD) and Vogt-Koyanagi-Harada (VKH) syndrome using a polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) assay. Haplotype and linkage disequilibrium (LD) analysis were performed by Haploview4.2. IRF8 mRNA expression and cytokine production was tested by real-time PCR and ELISA. Two SNPs near IRF8 were associated with BD (for rs17445836 GG genotype, Pc = 9.56 × 10⁻⁸, OR = 2.044; for rs11642873 AA genotype, Pc = 9.24 × 10⁻⁷, OR = 1.776). No significant association was found for the 13 SNPs tested with VKH syndrome. Haplotype analysis of the two positive SNPs revealed that the AG haplotype was significantly increased in BD patients (Pc = 2.60 × 10⁻⁸, OR = 1.646). Functional studies revealed an increased mRNA expression of IRF8 and IFN-γ production and a decreased production of IL-10 in rs17445836 carriers with the GG genotype. Increased expression of IRF8 as well as IFN-γ production and a decreased production of IL-10 were found in individuals carrying the rs11642873/AA genotype. In conclusion, this study indicates that IRF8 may contribute to the genetic susceptibility of BD by regulating IRF8 expression and cytokine production.

Acquired familial Mediterranean fever associated with a somatic MEFV mutation in a patient with JAK2 associated post-polycythemia myelofibrosis

Background

A study was designed to identify the source of fever in a patient with post-polycythemia myelofibrosis, associated with clonal Janus Kinase 2 (JAK2) mutation involving duplication of exon 12. The patient presented with 1–2 day long self-limited periodic episodes of high fever that became more frequent as the hematologic disease progressed.

Methods

After ruling out other causes for recurrent fever, analysis of the pyrin encoding Mediterranean fever gene (MEFV) was carried out by Sanger sequencing in peripheral blood DNA samples obtained 4 years apart, in buccal cells, laser dissected kidney tubular cells, and FACS-sorted CD3-positive or depleted mononucleated blood cells. Hematopoeitc cells results were validated by targeted deep sequencing. A Sanger sequence based screen for pathogenic variants of the autoinflammatory genes NLRP3, TNFRSF1A and MVK was also performed.

Results

A rare, c.1955G>A, p.Arg652His MEFV gene variant was identified at negligible levels in an early peripheral blood DNA sample, but affected 46 % of the MEFV alleles and was restricted to JAK2-positive, polymorphonuclear and CD3-depleted mononunuclear DNA samples obtained 4 years later, when the patient experienced fever bouts. The patient was also heterozygous for the germ line, non-pathogenic NLRP3 gene variant, p.Q705K. Upon the administration of colchicine, the gold standard treatment for familial Mediterranean fever (FMF), the fever attacks subsided.

Conclusions

This is the first report of non-transmitted, acquired FMF, associated with a JAK2 driven clonal expansion of a somatic MEFV exon 10 mutation. The non-pathogenic germ line NLRP3 p.Q705K mutation possibly played a modifier role on the disease phenotype.

Crystal structure of TRIM20 C-terminal coiled-coil/B30.2 fragment: implications for the recognition of higher order oligomers

Many tripartite motif-containing (TRIM) proteins, comprising RING-finger, B-Box, and coiled-coil domains, carry additional B30.2 domains on the C-terminus of the TRIM motif and are considered to be pattern recognition receptors involved in the detection of higher order oligomers (e.g. viral capsid proteins). To investigate the spatial architecture of domains in TRIM proteins we determined the crystal structure of the TRIM20Δ413 fragment at 2.4 Å resolution. This structure comprises the central helical scaffold (CHS) and C-terminal B30.2 domains and reveals an anti-parallel arrangement of CHS domains placing the B-box domains 170 Å apart from each other. Small-angle X-ray scattering confirmed that the linker between CHS and B30.2 domains is flexible in solution. The crystal structure suggests an interaction between the B30.2 domain and an extended stretch in the CHS domain, which involves residues that are mutated in the inherited disease Familial Mediterranean Fever. Dimerization of B30.2 domains by means of the CHS domain is crucial for TRIM20 to bind pro-IL-1β in vitro. To exemplify how TRIM proteins could be involved in binding higher order oligomers we discuss three possible models for the TRIM5α/HIV-1 capsid interaction assuming different conformations of B30.2 domains.

Non-canonical manifestations of familial Mediterranean fever: a changing paradigm

Paroxysmal crises of fever and systemic inflammation herald familial Mediterranean fever (FMF), considered as the archetype of all inherited systemic autoinflammatory diseases. Inflammatory bouts are characterized by short-term and self-limited abdominal, thoracic, and/or articular symptoms which subside spontaneously. Erysipelas-like findings, orchitis, and different patterns of myalgia may appear in a minority of patients. In recent years, many non-classical manifestations have been reported in the clinical context of FMF, such as vasculitides and thrombotic manifestations, neurologic and sensory organ abnormalities, gastrointestinal diseases, and even macrophage activation syndrome. As FMF left unrecognized and untreated is ominously complicated by the occurrence of AA-amyloidosis, it is highly desirable that diagnosis of this autoinflammatory disorder with its multiple clinical faces can be contemplated at whatever age and brought forward.

Clinical and genetic profile of children with periodic fever syndromes from a single medical center in South East Michigan

OBJECTIVE

To report a cohort of children with periodic fever syndromes (PFS) from Southeast Michigan.

METHODS

A retrospective review of medical records for patients referred for periodic fever over 5 years.

RESULTS

Sixty-six patients including 21 FMF, 15 PFAPA, four TRAPS and one patient with combined HIDS and FMF were included. In addition, 25 patients were categorized as clinical PFS (cPFS) based on their clinical features however their genetic workup was either negative or inconclusive. Majority of the patients with FMF were from Middle Eastern background (88 %), but positive family history was noted in only 55 % of cases. Mean age at diagnosis was 40.8 months with a mean delay in diagnosis of 24 months. Most common MEFV mutations were p.M694V and p.M694I. Four patients with TRAPS were from mixed European descent and age at onset of symptoms was 6, 12, 12, and 84 months respectively. TNFRSF1A sequence variants in the TRAPS patients included p.R121Q (R92Q) and p.C99G (C70G); one patient had a rare occurrence of a concurrent p.V726A/-MEFV mutation. One patient with HIDS and FMF presented with atypical overlapping PFS clinical manifestations and genetic evaluation showed a unique combination of p.I268T/p.V377I MVK mutations and p.E230K/-MEFV variant. All patients with PFAPA group were from mixed European descent, symptoms started at a mean age of 34.6 months with a mean delay in diagnosis of 23.3 months. Symptoms started during infancy in six patients. All patients fulfilled the diagnostic criteria for PFAPA. The mean age of onset of symptoms in cPFS group was 17.2 months. Empiric colchicine and glucocorticosteroids controlled flares in majority of patients with cPFS. No evidence of amyloidosis was found in this entire cohort of 66 patients after a mean of 29.2 months of follow-up.

CONCLUSION

PFS can present with atypical manifestations and should not be excluded based on a negative family history. Concomitant mutations in different autoinflammatory disorders genes can be present and possibly explain atypical manifestations. Various therapies may be considered even if genetic testing is inconclusive or negative.

Familial mediterranean fever: a fascinating model of inherited autoinflammatory disorder

BACKGROUND

Familial Mediterranean fever (FMF) is a rare inherited autosomal recessive autoinflammatory disorder characterized by recurrent and self-limited episodes of fever and painful serositis, lasting 1-3 days. FMF occurs almost exclusively among ethnic groups of the Mediterranean basin, although cases have also been found in Japan and Korean populations. Diagnosis is based on clinical features, response to colchicine and genetic analysis. Novel drugs are emerging, allowing better management of colchicine-resistant/colchicine-intolerant patients. This review aims to attract the attention of the readers on differential diagnosis and management of patients with FMF.

METHODS

The current state-of-the-art on FMF is outlined, with respect to epidemiological, genetic, pathophysiological and therapeutic characteristics, based on critical analysis of solid scientific literature.

RESULTS

FMF is more frequent than it was thought before. The phenotypic expression of M694V is more severe than that of V726A. Patients with M694V/M694V homozygosity are exposed to a higher risk of developing renal amyloidosis, arthritis, dermatologic and oral lesions, higher fever and more frequent painful attacks. Life-long therapy with colchicine (1·0-2·4 mg/day) is effective and safe to prevent recurrent attacks and renal amyloidosis and to reverse proteinuria. In nonresponder patients, alternative novel approaches include interleukin-1 receptor antagonist anakinra and the interleukin-1 decoy receptor rilonacept.

CONCLUSIONS

The prognosis of FMF is normal if AA amyloidosis is prevented. Colchicine remains the first-line therapy to treat pain and prevent amyloidosis. A follow-up should include clinical evaluation, therapeutic adjustments, measurement of serum amyloid A and proteinuria.

The gut microflora and its variety of roles in health and disease

The intestinal microbiota is a complex community of microorganisms that colonizes the gastrointestinal tract. The composition of the intestinal microbiota and the number of microorganisms differ in dependency of the local environmental conditions. The intestinal microbiota has an important impact on the development of the intestinal architecture and function, it influences the development of the gut-associated immune system, and epithelial cell functions. One of the most important functions of the intestinal microbiota is the prevention of bacterial overgrowth and susceptibility to infection with enteropathogenic organisms. Additionally, the intestinale microbiota plays a crucial role in the development of the systemic immunity and has an important influence on the host nutrition and metabolism. However, in genetically predisposed hosts, the intestinal microbiota is involved in the pathophysiology of inflammatory bowel diseases and pouchitis. Additionally, recent studies suggest that there might be an inflammation triggering effect of the intestinal microbiota in necrotizing enterocolitis. Here, we give an overview of the intestinal microbiota and its variety of roles in health and disease.

The role of interferon-β in the treatment of multiple sclerosis and experimental autoimmune encephalomyelitis - in the perspective of inflammasomes

Inflammasomes in innate immune cells mediate the induction of inflammation by sensing microbes and pathogen-associated/damage-associated molecular patterns. Inflammasomes are also known to be involved in the development of some human and animal autoimmune diseases. The Nod-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is currently the most fully characterized inflammasome, although a limited number of studies have demonstrated its role in demyelinating autoimmune diseases in the central nervous system of humans and animals. Currently, the development of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), is known to be induced by the NLRP3 inflammasome through enhanced recruitment of inflammatory immune cells in the central nervous system. On the other hand, interferon-β (IFNβ), a first-line drug to treat MS, inhibits NLRP3 inflammasome activation, and ameliorates EAE. The NLRP3 inflammasome is indeed a factor capable of inducing EAE, but it is dispensable when EAE is induced by aggressive disease induction regimens. In such NLRP3 inflammasome-independent EAE, IFN-β treatment is generally not effective. This might therefore be one mechanism that leads to occasional failures of IFN-β treatment in EAE, and possibly, in MS as well. In the current review, we discuss inflammasomes and autoimmunity; in particular, the impact of the NLRP3 inflammasome on MS/EAE, and on IFN-β therapy.

Inheritance of autoinflammatory diseases: shifting paradigms and nomenclature

Over 15 years have passed since the discovery of the first autoinflammatory gene, MEFV, responsible for familial Mediterranean fever. The identification of another gene, TNFRSF1A, in 1999 led to the concept of autoinflammation which characterises rheumatological conditions triggered by a defective innate immunity. Substantive progress has been made since then with the identification of 18 autoinflammatory genes accounting for up to 24 disease entities showing overlapping symptoms. The accumulation of studies reporting patients with missing or excess mutations as compared with expected numbers favours the hypothesis that these diseases are distributed along a continuum ranging from monogenic to multifactorial conditions, rather than featuring only classical modes of inheritance. Moreover, the probable interactions of environmental and epigenetic factors further obscure our understanding of the mechanisms underlying the phenotypic expression of patients. This review explores the history of autoinflammatory gene discovery, discusses the nosological disparities stemming from the clinical versus pathophysiological definition of autoinflammatory diseases and summarises various inheritance patterns. This review calls for a consistent disease nomenclature and presents a reconciling hypothesis which places different sequence variants within the autoinflammatory disease continuum. Integrating these new concepts should help to facilitate communication between health professionals and promote personalised patient care.

The association of TNFRSF1A gene and MEFV gene mutations with adult onset Still's disease

Adult onset Still's disease (ASD) is a systemic inflammatory disorder of unknown etiology. ASD is characterized by fever with unknown etiology, rash, arthritis, and involvement of several organ systems. FMF and TRAPS are two important autoinflammatory diseases which characterized with recurrent inflammatory attacks. We aimed in this study to investigate the MEFV gene and TNFRSF1A gene variations in ASD. Twenty consecutive Turkish ASD patients (14 female and 6 male; mean age 38.45 ± 14; mean disease duration 3.3 ± 2.3; mean age of the disease onset 35.1 ± 14.4) and 103 healthy controls of Turkish origin were analyzed. All ASD patients were genotyped for the 4 MEFV mutations (M694V, E148Q, V726A, M680I) and TNFRSF1A gene exon 2-3 and exon 4-5 by using sequence analysis. The healthy controls are genotyped using PCR-RFLP method for intron 4 variation. The results of MEFV gene mutations screening show an increase in the MEFV mutation rate in ASD group, but it was not significantly different (p = 0.442, OR 1.64, 95 % CI 0.409-6.589). T-C polymorphism (rs1800692) was the only variation in the intron 4 of TNFRSF1A gene that we observed at the ASD patients. The frequency of TT genotype was 15 %, TC: 45 %, and CC: 40 % in ASD patients and the frequencies were 22, 41, and 37 % in healthy controls, respectively. When we analyzed the allele difference between both groups, there was no difference (p = 0.54, OR 1.24, 0.619-2.496-2.654). The variations in MEFV may have role in ASD pathogenesis. Our findings suggest that there is no significant association between ASD and TNFRSF1A variations.

MEFV E148Q polymorphism is associated with Henoch-Schönlein purpura in Chinese children

Henoch-Schönlein purpura (HSP) is a multifactorial inflammatory disease whose pathogenesis remains unknown. Pyrin encoded by the MEFV gene (NM_000243; OMIM 608107) is an important active member of the inflammasome and has been shown to affect the expression of many of the genes involved in immune and inflammatory responses. The aim of our study was to elucidate the possible roles of MEFV genetic variants on the susceptibility to HSP and its clinical outcomes in 78 patients with HSP and 189 controls in China. A significant association was found between the E148Q polymorphism (G->C) and HSP susceptibility (odds ratio 2.76, 95% confidence interval 1.76-4.34, P=0.0001). The C allele of E148Q was associated with joint involvement (P=0.014) but not with HSP nephritis (P=0.1). The clinical score was higher in subjects with the CC genotype than in those with the CG or GG genotype (4.13+/-3.53 vs. 1.94+/-1.70, respectively; P=0.011). P369S was not associated with HSP or other phenotypes. M694V and M680I were absent in our patients. Our results suggest that MEFV E148Q could be a contributory genetic factor to HSP and HSP-related joint syndromes.

Monogenic autoinflammatory diseases: new insights into clinical aspects and pathogenesis

PURPOSE OF REVIEW

The genetic and clinical characterizations of monogenic autoinflammatory syndromes have led to ground breaking insights into the regulation of inflammatory responses to endogenous and exogenous inducers or triggers of inflammation and continue to uncover key inflammatory pathways of the innate immune system. This article summarizes recent progress in the clinical aspects and understanding of the pathogenesis of this growing spectrum of diseases.

RECENT FINDINGS

The understanding of the spectrum of organ manifestations in autoinflammation was expanded by the discovery of two novel monogenic diseases both caused by the absence of an anti-inflammatory signal and added evidence that increased IL-1 signaling can cause aseptic osteolytic bone lesions and that the absence of IL-10 signaling causes inflammatory enterocolitis in neonates. New knock in animal models for TNF-receptor-associated periodic syndrome, and familial Mediterranean fever and cryopyrin-associated periodic syndromes allow insights into the complexity of the dysregulated immune pathways. Exploring 'triggers' of the NLRP3 inflammasome spurred studies of tissue inflammation in diseases including gout and those that previously have not been considered inflammatory in nature such as diabetes, fibrosing lung disease and possibly coronary artery disease.

SUMMARY

The genetic characterization of a growing number of monogenic autoinflammatory diseases has provided important insights into the phenotypic expression of single gene disorders and the complexity of the dysregulated inflammatory pathways leading to clinical disease. Knowledge obtained from these disorders is pertinent to a number of common disorders and provides new targets for drug development.