Update on genetics and pathogenesis of autoinflammatory diseases: the last 2 years

Endoscopic characterization of gastrointestinal manifestations in children with undifferentiated recurrent fever

BACKGROUND AND STUDY AIMS

Systemic autoinflammatory diseases are characterized by recurrent or chronic inflammation, and monogenic forms are increasingly defined. However, a group of patients without genetic diagnosis is called the syndrome of undifferentiated recurrent fever (SURF). This study analyzed the clinical and endoscopic features of patients with SURF presenting with gastrointestinal (GI) symptoms.

PATIENTS AND METHODS

Between 2019 and 2022, GI endoscopy were performed in patients with SURF who presented with GI symptoms. Clinical, genetic, laboratory, and endoscopy findings were analyzed.

RESULTS

Fifteen patients were included in the study, eight (53.3 %) were girls. The mean age was 10.5 ± 5.80 years, and the median age at symptom onset was 4 (0.3-16) years. All patients experienced fever and abdominal pain. Thirteen patients (86.7 %) experienced diarrhea, 11 (73.3 %) reported myalgia, and 10 (66.7 %) had joint involvement. Lymphoid follicles in the terminal ileum mucosa were detected in 10 patients (66.7 %), and nodular lymphoid hyperplasia in the terminal ileum was the histopathological finding in 12 patients (80 %).

CONCLUSIONS

The current study found that patients with SURF experiencing gastrointestinal symptoms have excessive lymph node formation in the terminal ileal mucosa due to an exaggerated inflammatory response. This may be the cause of their GI symptoms.

Immunogenetics of the Ocular Anterior Segment: Lessons from Inherited Disorders

Autoimmune and autoinflammatory diseases cause morbidity in multiple organ systems including the ocular anterior segment. Genetic disorders of the innate and adaptive immune system present an avenue to study more common inflammatory disorders and host-pathogen interactions. Many of these Mendelian disorders have ophthalmic manifestations. In this review, we highlight the ophthalmic and molecular features of disorders of the innate immune system. A comprehensive literature review was performed using PubMed and the Online Mendelian Inheritance in Man databases spanning 1973-2020 with a focus on three specific categories of genetic disorders: RIG-I-like receptors and downstream signaling, inflammasomes, and RNA processing disorders. Tissue expression, clinical associations, and animal and functional studies were reviewed for each of these genes. These genes have broad roles in cellular physiology and may be implicated in more common conditions with interferon upregulation including systemic lupus erythematosus and type 1 diabetes. This review contributes to our understanding of rare inherited conditions with ocular involvement and has implications for further characterizing the effect of perturbations in integral molecular pathways.

Autoinflammatory disease with focus on NOD2-associated disease in the era of genomic medicine

Systemic autoinflammatory diseases (SAIDs) represent a spectrum of genetically heterogeneous inflammatory disorders. Some SAID-associated genes are located in chromosome 16, including familial Mediterranean fever gene (MEFV) and nucleotide-binding oligomerization domain 2 [NOD2] gene that are linked to Crohn's disease, Blau syndrome, and Yao syndrome. These disorders share overlapping clinical phenotypes, and genotyping is diagnostically helpful and distinctive. Using next generation sequencing in SAIDs, digenic variants or combinations of more genetic variants in different genes can be detected, and they may be related to the MEFV and NOD2 genes. These variants may contribute to heterogeneous phenotypes in an individual, complicating the diagnosis and therapy. An awareness of the clinical significance of the digenic or combined gene variants is important in the era of genomic medicine.

A Systematic Analysis of Treatment and Outcomes of NOD2-Associated Autoinflammatory Disease

OBJECTIVES

Yao syndrome, formerly named NOD2-associated autoinflammatory disease, is a periodic disease characterized by fever, dermatitis, polyarthritis/leg swelling, and gastrointestinal and sicca-like symptoms associated with specific NOD2 sequence variants. Our aim was to evaluate the treatment and outcomes of the disease.

METHODS

A total of 52 adult patients with autoinflammatory disease phenotype were diagnosed with Yao syndrome and enrolled at the Cleveland Clinic between November 2009 and May 2015. All patients were genotyped for the NOD2 variants, and systematically studied for treatment outcomes.

RESULTS

Among the 52 Yao syndrome patients, all were white, and 72% were women. The mean age at diagnosis was 38.0 ± 12.0 years, and the disease duration was 8.8 ± 5.8 years. In the multi-organ disease, more common and typical manifestations were recurrent dermatitis and inflammatory arthritis with or without distal leg swelling besides recurrent fever. It was genotypically associated with the NOD2 IVS8⁺¹⁵⁸ or R702W. Therapeutically, glucocorticoids markedly decreased the disease severity and duration of flares in 19 patients (36.6%), sulfasalazine treatment achieved a significant symptomatic improvement in 22 (42%) patients, and 3 patients received canakinumab or tocilizumab with benefits. Prognostically, 13% of the 52 patients had somewhat physical impairment, and there was no mortality during the follow-up. Associated comorbidities were fibromyalgia, asthma, renal stones, and ventricular hypertrophy.

CONCLUSIONS

As a systemic disease, Yao syndrome uncommonly affects the solid internal organs, but it can be complicated with chronic pain syndrome and even disability. Glucocorticoids or sulfasalazine may be considered as the first-line treatment option, and interleukin (IL)-1/IL-6 inhibitors may be tried for refractory cases. The potential associations between certain comorbidities and Yao syndrome deserve further study.

NLRP12 autoinflammatory disease: a Chinese case series and literature review

As one of the systemic autoinflammatory diseases (SAIDs), the nucleotide-binding oligomerization domain-like receptor protein (NLRP)12 autoinflammatory disease (NLRP12-AD) is an autosomal dominant disorder associated with NLRP12 mutation. SAIDs have been hardly reported in the Chinese population, and NLRP12-AD has been reported only in Caucasians. We report the first case series of NLRP12-AD in the Chinese population coupled with literature review. Three Han Chinese adult patients with clinical phenotype suggestive of NLRP12-AD carrying NLRP12 variants were treated by the authors in 2015. Their phenotype and genotype were carefully studied. A PubMed search for SAIDs was conducted between January, 1990 and January, 2016, and we focused on NLRP12-AD. All three adult patients developed periodic disease in adulthood. They presented with recurrent fever (n = 3), polyarthralgia (n = 3), myalgia (n = 3), urticaria (n = 2), lymphadenopathy (n = 2), and erythema nodosa (n = 1). All patients carry the NLRP12 mutation F402L. Based upon our analysis of a total of 26 patients with NLRP12-AD in the literature, both familial and sporadic cases were equally reported and late-onset cases accounted for 28 %. NLRP12-AD patients typically present with periodic fever, urticaria-like rash, arthralgia/arthritis, myalgia, and lymphadenopathy. Genotyping identifies the NLRP12 gene mutations, notably F402L (55 %). Relative to the literature reports, our patients had the similar phenotypic and genotypic features. Patients with NLRP12-AD usually respond to glucocorticoid therapy. Our report is the first to confirm the presence of NLRP12-AD in the Chinese population. It highlights the importance of screening NLRP12 in patients with unexplained periodic fever syndrome.

Anakinra as a diagnostic challenge and treatment option for systemic autoinflammatory disorders of undefined etiology

BACKGROUND

Some adult patients presenting with unexplained pyrexia, serositis, skin rashes, arthralgia, myalgia, and other symptoms commonly found in autoinflammatory disorders may not fit a specific diagnosis, either because their clinical phenotype is nondiagnostic or genetic tests are negative. We used the term undifferentiated systemic autoinflammatory disorder (uSAID) to describe such cases. Given that well-defined autoinflammatory diseases show responses to IL-1 blockade, we evaluated whether anakinra was useful for both diagnosing and treating uSAID patients.

METHODS

We performed a retrospective analysis of consecutive patients presenting with uSAID between 2012-2015 who were treated with the recombinant IL-1 receptor antagonist anakinra. uSAID was diagnosed after excluding malignancy, infection, and pathogenic mutations in known hereditary fever syndromes (HFS) genes and where clinical criteria for adult onset Still's disease (AOSD) were not met.

RESULTS

A total of 11 patients presented with uSAID (5 males and 6 females), with a mean time to diagnosis of 3.5 years (1-8 years). Patients were unresponsive or only partially controlled on disease-modifying antirheumatic drug (DMARD)/steroid treatment. Anakinra controlled symptoms within 4-6 weeks of starting treatment in 9 of 11 cases. Two patients discontinued therapy - one due to incomplete response and another due to severe injection-site reactions.

CONCLUSION

This retrospective case series demonstrates that the spectrum of poorly defined autoinflammatory disorders that show responsiveness to anakinra is considerable. Anakinra seems a viable treatment option for these patients, who are unresponsive to standard steroid/DMARD treatments. Moreover, given the mechanisms of action, response to anakinra implicates underlying IL-1 dysregulation in the disease pathogenesis of responding uSAIDs patients.

Shaping the spectrum - From autoinflammation to autoimmunity

Historically, autoimmune-inflammatory disorders were subdivided into autoinflammatory vs. autoimmune diseases. About a decade ago, an immunological continuum was proposed, placing "classical" autoinflammatory disorders, characterized by systemic inflammation in the absence of high-titer autoantibodies or autoreactive T lymphocytes, at the one end, and autoimmune disorders at the other end. We provide an overview of recent developments and observations, filling in some of the gaps and showing strong interconnections between innate and adaptive immune mechanisms, indicating that disorders from both ends of the immunological spectrum indeed share key pathomechanisms. We focus on three exemplary disorders: i) systemic juvenile idiopathic arthritis representing "classical" autoinflammatory disorders; ii) psoriasis, a mixed pattern disease; and iii) systemic lupus erythematosus, a prototypical autoimmune disease. We summarize scientific observations suggesting that, depending on disease stages and/or duration, individualized treatment targeting innate or adaptive immune mechanisms in disorders from either end of the immunological spectrum may control disease activity.

Failure to thrive, interstitial lung disease, and progressive digital necrosis with onset in infancy

Key teaching points • SAVI is a recently described interferonopathy resulting from constitutive action of STING and up-regulation of IFN-β signaling. • SAVI is characterized by facial erythema with telangiectasia, acral/cold-sensitive tissue ulceration and amputations, and interstitial lung disease. It has overlapping features with Aicardi-Goutières syndrome and familial chilblain lupus. • Traditional immunosuppressive medications and biologic therapies appear to be of limited benefit, but JAK inhibitors may impact disease progression.

Nur77 deficiency leads to systemic inflammation in elderly mice

Background

Nur77, an orphan member of the nuclear receptor superfamily, has been implicated in the regulation of inflammation. However, the in vivo function of Nur77 remains largely unexplored. In the current study, we investigated the role of Nur77 in inflammation and immunity in mice.

Findings

We found that elderly 8-month-old Nur77-deficient mice (Nur77^−/−) developed systemic inflammation. Compared to wild-type (WT) mice (Nur77^+/+), Nur77^−/− mice showed splenomegaly, severe infiltration of inflammatory cells in several organs including liver, lung, spleen and kidney, increased hyperplasia of fibrous tissue in the lung and enlargement of kidney glomeruli. Additionally, Nur77^−/− mice had increased production of pro-inflammatory cytokines and immunoglobulin, and elicited pro-inflammatory M1-like polarization in macrophages as revealed by increased expression of CXCL11 and INDO, and decreased expression of MRC1.

Conclusions

These in vivo observations provide evidence for a pivotal role for Nur77 in the regulation of systemic inflammation and emphasize the pathogenic significance of Nur77 in vivo.

Electronic supplementary material

The online version of this article (doi:10.1186/s12950-015-0085-0) contains supplementary material, which is available to authorized users.