Blau syndrome-associated uveitis and the NOD2 gene

Blau syndrome with NOD2 mutation in a 54-year-old man: A case report

Blau syndrome (BS) is a rare genetic immune disease which commonly presents in childhood. Currently, the miss-rate of BS diagnosis is very high, and an effective clinical management of BS has not been well established. This case report depicts a 54-year-old male Chinese patient presenting with hand malformation, fever, skin rash and joint pain. His diagnosis was ultimately confirmed according to typical medical history and genetic analysis. This case report will further help clinicians to be aware of this rare clinical entity for correct diagnosis and proper treatment.

Blau syndrome with persistent fetal vasculature: a case report

BACKGROUND

Blau Syndrome (BS) is a rare autosomal dominant noncaseous granulomatous disease caused by mutations in the NOD2 gene. The disease is characterized by granulomatous dermatitis, symmetrical arthritis, and uveitis, which, if left untreated, can progress to blindness. The diagnosis of BS can be challenging because of its rarity and overlap with other rheumatologic disorders. Early detection of ocular involvement is critical to prevent vision loss and improve the prognosis of patients with BS.

CASE PRESENTATION

In this report, we present a case of a five-year-old Chinese girl diagnosed with BS one year ago after presenting with a systemic rash and urinary calculi. Genetic testing was recommended by a physician, and a heterozygous mutation of the NOD2 gene c.1538T > C (p.M513T) was identified. Eight months ago, due to bilateral corneal punctate opacity, we had examined and diagnosed bilateral uveitis, bilateral corneal zonal degeneration, persistent fetal vasculature (PFV) in the right eye, and perivascular granuloma in the right eye. As a result, Vitrectomy was performed on the right eye, resulting in a significant improvement in visual acuity from 1/50 on the first day after surgery to 3/10 after 1 week. After 6 months, the visual acuity of the right eye was maintained at 3/20, but opacification of the lens posterior capsule was observed. Follow-up appointments are ongoing to monitor the condition of the affected eyes. Our report underscores the importance of prompt detection and management of ocular involvement in BS accompany with PFV to prevent vision loss and improve patient outcomes.

CONCLUSIONS

This report details the case of a child diagnosed with BS who accompanied a periretinal granuloma and PFV in the right eye. Regrettably, the left eye was observed to have no light perception (NLP) with the fundus not being visible. The occurrence of ocular complications in patients with BS, must be closely monitored to prevent vision loss and enhance treatment outcomes. This case underscores the importance of prompt diagnosis and management of ocular complications in patients with BS to prevent further damage and optimize patient outcomes.

Potential Benefits of TNF Targeting Therapy in Blau Syndrome, a NOD2-Associated Systemic Autoinflammatory Granulomatosis

Blau syndrome is a systemic autoinflammatory granulomatous disease caused by mutations in the nucleotide-binding oligomerization domain 2 (NOD2) gene. NOD2 is an intracellular pathogen recognition receptor. Upon binding to muramyl dipeptide (MDP), NOD2 activates the NF-κB pathway, leading to the upregulation of proinflammatory cytokines. Clinical manifestations of Blau syndrome appear in patients before the age of four. Skin manifestations resolve spontaneously in some cases; however, joint and eye manifestations are progressive, and lead to serious complications, such as joint contracture and blindness. Currently, there is no specific curative treatment for the disease. Administration of high-dose oral steroids can improve clinical manifestations; however, treatments is difficult to maintain due to the severity of the side effects, especially in children. While several new therapies have been reported, including JAK inhibitors, anti-IL-6 and anti-IL-1 therapies, anti-TNF therapy plays a central role in the treatment of Blau syndrome. We recently performed an ex vivo study, using peripheral blood and induced pluripotent stem cells from patients. This study demonstrated that abnormal cytokine expression in macrophages from untreated patients requires IFNγ stimulation, and that anti-TNF treatment corrects the abnormalities associated with Blau syndrome, even in the presence of IFNγ. Therefore, although the molecular mechanisms by which the genetic mutations in NOD2 lead to granuloma formation remain unclear, it is possible that prior exposure to TNFα combined with IFNγ stimulation may provide the impetus for the clinical manifestations of Blau syndrome.

Bilateral Optic Disc Swelling as a Plausible Common Ocular Sign of Autoinflammatory Diseases: Report of Three Patients with Blau Syndrome or Cryopyrin-Associated Periodic Syndrome

The aim of this study is to describe bilateral optic disc swelling in three consecutive patients with Blau syndrome or cryopyrin-associated periodic syndrome at a single institution. Case 1 was a 30-year-old woman receiving 25 mg etanercept twice weekly who had been diagnosed as early-onset sarcoidosis by biopsy of skin rashes at 5 months old and genetically diagnosed with Blau syndrome with CARD15/NOD2 mutation (N670K) at 13 years old. At 10 years old, she began to have uveitis with optic disc swelling in both eyes, resulting in macular degeneration and optic disc atrophy at 17 years old only when etanercept was introduced. Case 2 was a 21-year-old man receiving adalimumab every 2 weeks who had been diagnosed as early-onset sarcoidosis by biopsy of skin rashes at 1.5 years old and genetically diagnosed as Blau syndrome with CARD15/NOD2 mutation (C495Y) at 5 years old. At 8 years old, around the time of adalimumab introduction, he began to show bilateral optic disc swelling which continued until the age of 16 years when the dose of adalimumab was increased. Case 3 was a 20-year-old woman receiving canakinumab every 8 weeks for systemic symptoms such as fever, headache, vomiting, and abdominal pain and later for sensorineural hearing disturbance on both sides. She had been diagnosed genetically with cryopyrin-associated periodic syndrome with NLRP3 mutation (Y859C) at 7 years old. At 5 years old, she was found to have bilateral optic disc swelling, which continued until the age of 10 years when she began receiving canakinumab (IL-1β inhibitor). Bilateral optic disc swelling might be tentatively designated as a plausible common ocular feature, if it occurred, in autoinflammatory diseases to pay more attention to ophthalmic complications in rare diseases.

Blue Light Induces Impaired Autophagy through Nucleotide-Binding Oligomerization Domain 2 Activation on the Mouse Ocular Surface

In this study, we investigated the effects of blue light exposure on nucleotide-binding oligomerization domain 2 (NOD2) expression on the mouse ocular surface and evaluated the role of NOD2 activation in light-induced cell death. Mice were divided into wild-type (WT), NOD2-knock out (KO), WT + blue light (WT + BL), and NOD2-KO + blue light (NOD2-KO + BL) groups, and the mice in the WT+BL and NOD2-KO + BL groups were exposed to blue light for 10 days. After 10 days of blue light exposure, increased reactive oxygen species and malondialdehyde were observed in the WT + BL and NOD2-KO + BL groups, and the WT + BL group showed a higher expression of NOD2 and autophagy related 16 like 1. Although both WT+BL and NOD2-KO + BL groups showed an increase in the expression of light chain 3-II, NOD2-KO + BL mice had a significantly lower p62 expression than WT + BL mice. In addition, NOD2-KO+BL mice had significantly lower corneal epithelial damage and apoptosis than WT + BL mice. In conclusion, blue light exposure can induce impaired autophagy by activation of NOD2 on the ocular surface. In addition, the reactive oxygen species (ROS)-NOD2-autophagy related 16 like 1 (ATG16L) signaling pathway may be involved in the blue-light-induced autophagy responses, resulting in corneal epithelial apoptosis.

Manifestation of panuveitis after intraocular surgery in a child with blau syndrome

Blau syndrome (BS) is a rare granulomatous disease with autosomal dominant inheritance. It is characterized by a triad of dermatitis, arthritis, and recurrent uveitis. This case presents the onset of panuveitis in BS after intraocular surgery. A 10-year-old boy presented to the outpatient clinic with retinal detachment in the left eye after 6 years following early-onset cataract surgery. Bilateral panuveitis occurred 3 weeks after surgical repair and resulted in a total visual loss in the left eye and was persistent to conventional treatment in the right eye. Genetic testing revealed a mutation in NOD2 gene. The addition of adalimumab to the treatment regimen resulted in long-term uveitis control and maintenance of 20/70 vision in the right eye. We propose that NOD2-mediated inflammatory cascade can be activated by intraocular surgery and results in the manifestation of BS.

Ocular manifestations of Blau syndrome

PURPOSE OF REVIEW

This article summarizes the systemic and ocular manifestations of Blau syndrome, its genetic basis, and reviews recently published literature.

RECENT FINDINGS

A large multicenter prospective case series is underway, with 3-year preliminary results indicating the prevalence of uveitis, clinical characteristics and early data on its visual prognosis. Case reports have demonstrated the successful use of newer biologic agents.

SUMMARY

Blau syndrome is an exceedingly rare autoinflammatory disorder with skin, joint and eye manifestations. It is caused by autosomal dominant mutations of the NOD2 protein. Eye involvement is typically a chronic bilateral granulomatous iridocyclitis, often with multifocal choroiditis in the posterior segment. Treatment starts with topical and systemic steroids and often requires antimetabolites or biologic agents.

Monogenic autoinflammatory diseases in children: single center experience with clinical, genetic, and imaging review

Purpose

1. To review the contemporary literature and present a list of the imaging findings for patients with autoinflammatory diseases from our hospital. All these patients are found to have a genetic mutation that is responsible for their disease.

2. To present follow-up imaging findings, when available, and correlate those with symptoms and type of treatment administered in approximately 40 patients with autoinflammatory diseases of a single tertiary pediatric health care center including familial Mediterranean fever, Cryopyrin-associated autoinflammatory syndrome, PAPA (pyogenic arthritis, pyoderma gangrenousum, and acne) syndrome, and more. These findings are related to disease progression, treatment response, or treatment-induced changes.

Conclusion

Autoinflammatory diseases are relatively rare entities that can affect any system of the body. Given the many nonspecific imaging features, awareness of these diseases and good communication with clinicians aid in reaching an accurate diagnosis.

NOD1 and NOD2 in inflammatory and infectious diseases

It has been long recognized that NOD1 and NOD2 are critical players in the host immune response, primarily by their sensing bacterial peptidoglycan-conserved motifs. Significant advances have been made from efforts that characterize their upstream activators, assembly of signaling complexes, and activation of downstream signaling pathways. Disruption in NOD1 and NOD2 signaling has also been associated with impaired host defense and resistance to the development of inflammatory diseases. In this review, we will describe how NOD1 and NOD2 sense microbes and cellular stress to regulate host responses that can affect disease pathogenesis and outcomes.

Clinical characteristics and treatment of 50 cases of Blau syndrome in Japan confirmed by genetic analysis of the NOD2 mutation

Objectives

To collect clinical information and NOD2 mutation data on patients with Blau syndrome and to evaluate their prognosis.

Methods

Fifty patients with NOD2 mutations were analysed. The activity of each NOD2 mutant was evaluated in HEK293 cells by reporter assay. Clinical information was collected from medical records through the attending physicians.

Results

The study population comprised 26 males and 24 females aged 0–61 years. Thirty-two cases were sporadic, and 18 were familial from 9 unrelated families. Fifteen different mutations in NOD2 were identified, including 2 novel mutations (p.W490S and D512V); all showed spontaneous nuclear factor kappa B activation, and the most common mutation was p.R334W. Twenty-six patients had fever at relatively early timepoints in the disease course. Forty-three of 47 patients had a skin rash. The onset of disease in 9 patients was recognised after BCG vaccination. Forty-five of 49 patients had joint lesions. Thirty-eight of 50 patients had ocular symptoms, 7 of which resulted in blindness. After the diagnosis of Blau syndrome, 26 patients were treated with biologics; all were antitumour necrosis factor agents. Only 3 patients were treated with biologics alone; the others received a biologic in combination with methotrexate and/or prednisolone. None of the patients who became blind received biologic treatment.

Conclusions

In patients with Blau syndrome, severe joint contractures and blindness may occur if diagnosis and appropriate treatment are delayed. Early treatment with a biologic agent may improve the prognosis.

Expression and Role of Nucleotide-Binding Oligomerization Domain 2 (NOD2) in the Ocular Surface of Murine Dry Eye

Purpose

To investigate expression and role of nucleotide-binding oligomerization domain 2 (NOD2) in the ocular surface of experimental dry eye (EDE), which is a nod-like receptor member and is involved in innate immune response.

Methods

C57/BL6 female mice were divided into the groups: untreated (UT), EDE, and NOD2 knockout (KO) mice exposed to desiccating stress for 14 days. Clinical parameters and levels of inflammatory cytokine were measured at 3,5,7, and 14 days. Immunofluorescent staining for NOD2 and Western blot for RIP2 and NF-κB were performed at 14 days. Flow cytometry, PAS staining and TUNEL staining were performed.

Results

After EDE induction, NOD2 was expressed in the corneal epithelium of the EDE group. The EDE group showed a significantly increased RIP2 expression compared to the UT and NOD2-KO groups. A significantly lower expression of NF-κB and lower levels of IL-1β, IL-6, IFN-γ, and TNF-α were noted in the NOD2-KO group than in the EDE group. The NOD2-KO group had lower CD11b+ and CD4+CCR5+ T cells, TUNEL-positive cells and corneal staining score and higher density of conjunctival goblet cell density, tear volume, and tear film break-up time than the EDE group. The UT group showed significant differences in inflammatory and clinical parameters compared to the EDE and NOD2-KO groups.

Conclusions

The NOD2 receptor pathway induced inflammation and apoptosis by activation of RIP2 and NF-κB on the ocular surface of EDE, thereby reducing tear secretion. Therefore, NOD2 pathway may be involved in the pathogenesis of dry eye.

Bilateral congenital macular coloboma and cataract: A case report

RATIONALE

The case with congenital macular coloboma and cataract was rarely reported, and the pathogenic gene of the disease is still not clear. Moreover, it is difficult to improve the visual acuity of the eye with this disease.

PATIENT CONCERNS

An 11-year-old boy presented low visual acuity and horizontal nystagmus in both eyes. Ophthalmologic examination showed the patient with bilateral congenital coloboma and cataract. The visual acuity of the patient improved slightly after cataract surgery. Heterozygous mutations of frizzled-4 (FZD4) and nucleotide-binding oligomerization domain-containing protein 2 (NOD2) were identified by next-generation sequencing in this case.

DIAGNOSIS

Congenital macular coloboma and cataract of both eyes.

INTERVENTIONS

We performed the standard phacoemulsification and intraocular lens implantation on both eyes of the patient for the treatment of congenital cataract, and then followed up the fundus lesions regularly.

OUTCOMES

Cataract surgery may improve the visual acuity of the eyes with congenital macular coloboma and cataract at some degree, but the vision of this patient was still very poor postoperatively. Furthermore, the heterozygous mutations of FZD4 and NOD2 were found in this patient.

LESSONS

Cataract surgery may improve the visual acuity of the eyes with congenital macular coloboma and cataract at some degree, and heterozygous mutations of FZD4 and NOD2 may be involved in the occurrence of congenital macular coloboma and cataract.

NOD2 genetic variants and sarcoidosis-associated uveitis

Purpose

Identifying genetic risk factors for developing sarcoidosis-associated uveitis could provide insights into its pathogenesis which is poorly understood.

We determine if variants in NOD2 confer an increased risk of developing uveitis in adults with sarcoidosis.

Methods

In this genetic case-control study, 51 total subjects were enrolled: 39 patients diagnosed with sarcoid-related uveitis and 12 patients with systemic sarcoidosis without ocular involvement as controls. Sanger sequencing of the eleven exons of the NOD2 gene was performed on DNA obtained from whole blood. Sanger sequencing data were aligned against the NOD2 NCBI-RefSeq reference sequence to identify novel mutations in uveitis patients. For common variants, allele frequencies in cases versus controls were compared using the chi-square test.

Results

There were no significant differences in NOD2 common variant allele frequencies between sarcoidosis patients with and without uveitis, and none of the pathogenic NOD2 mutations associated with Blau syndrome were found in this cohort. However, four rare, non-synonymous variants were identified in four patients with ocular sarcoidosis and none of the controls. Variants rs149071116, rs35285618, and 16:g.50745164T > C have never been previously reported to be associated with any disease and may be pathogenic. The fourth variant, rs2066845, is associated with Crohn’s disease and psoriatic arthritis.

Conclusions

Despite the phenotypic overlap between sarcoidosis and Blau syndrome, none of the established pathogenic NOD2 variants were present in adults with sarcoidosis. However, four novel, rare, non-synonymous variants were identified in four cases with ocular sarcoidosis. Further investigation is needed to explore the potential clinical significance of these polymorphisms.

Autoinflammatory granulomatous diseases: from Blau syndrome and early-onset sarcoidosis to NOD2-mediated disease and Crohn's disease

The recent identification of genetic mutations leading to dysfunction of inflammatory and apoptotic pathways, has allowed to characterise a group of diseases, recognised as monogenic autoinflammatory syndromes. Among those, Blau syndrome (BS) and early-onset sarcoidosis (EOS) have been identified as familial and sporadic phenotypes of the same non-caseating granulomatous form. Both the diseases are caused by mutations in the CARD15/NOD2 gene, encoding the cytosolic NOD2 protein, one of the key molecules in the regulation of innate immunity. Clinical onset is typically located in the first years of life and phenotype is characterised by simultaneous or less articular, cutaneous and ocular non-caseating granulomatous inflammation, which can be variably associated with a heterogeneous systemic spectrum. The CARD15/NOD2 gene has also been identified as one of the genes linked to susceptibility to Crohn's disease (CD), a common polygenic inflammatory granulomatous bowel disease. The heightened nuclear factor-κB activity, found in the intestinal tissue of patients affected by CD, has probably a genetic cause related to several CARD15/NOD2 polymorphisms. Other substitutions in the CARD15/NOD2 gene have also been found in a recently described disorder, called NOD2-associated autoinflammatory disease, which shares several clinical characteristics with BS and EOS. This review attempts to describe these diseases on the basis of the most recent evidences. We described genetic and clinical aspects, mainly focusing on BS and EOS, the most representative diseases of autoinflammatory granulomatous diseases, with the ultimate purpose to expand their knowledge.

A new mutation in blau syndrome

Blau syndrome is a rare, autosomal dominant, granulomatous autoinflammatory disease. The classic triad of the disease includes recurrent uveitis, granulomatous dermatitis, and symmetrical arthritis. Blau syndrome is related to mutations located at the 16q12.2-13 gene locus. To date, 11 NOD2 gene mutations causing Blau syndrome have been described. Here, we describe a 5-year-old male patient who presented with Blau syndrome associated with a novel sporadic gene mutation that has not been reported previously.

Caveats and truths in genetic, clinical, autoimmune and autoinflammatory issues in Blau syndrome and early onset sarcoidosis

Blau syndrome (BS) and early onset sarcoidosis (EOS) are, respectively, the familial and sporadic forms of the pediatric granulomatous autoinflammatory disease, which belong to the group of monogenic autoinflammatory syndromes. Both of these conditions are caused by mutations in the NOD2 gene, which encodes the cytosolic NOD2 protein, one of the pivotal molecules in the regulation of innate immunity, primarily expressed in the antigen-presenting cells. Clinical onset of BS and EOS is usually in the first years of life with noncaseating epithelioid granulomas mainly affecting joints, skin, and uveal tract, variably associated with heterogeneous systemic features. The dividing line between autoinflammatory and autoimmune mechanisms is probably not so clear-cut, and the relationship existing between BS or EOS and autoimmune phenomena remains unclear. There is no established therapy for the management of BS and EOS, and the main treatment aim is to prevent ocular manifestations entailing the risk of potential blindness and to avoid joint deformities. Nonsteroidal anti-inflammatory drugs, corticosteroids and immunosuppressive drugs, such as methotrexate or azathioprine, may be helpful; when patients are unresponsive to the combination of corticosteroids and immunosuppressant agents, the tumor necrosis factor-α inhibitor infliximab should be considered. Data on anti-interleukin-1 inhibition with anakinra and canakinumab is still limited and further corroboration is required. The aim of this paper is to describe BS and EOS, focusing on their genetic, clinical, and therapeutic issues, with the ultimate goal of increasing clinicians' awareness of both of these rare but serious disorders.

Blau syndrome polymorphisms in NOD2 identify nucleotide hydrolysis and helical domain 1 as signalling regulators

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NOD2 SNPs that cause Blau syndrome cluster in two regions of the NACHT.

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The ATP/Mg2+ binding pocket cluster are likely to dysregulate ATP hydrolysis.

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SNPs in helical domain 1 are predicted to influence receptor autoinhibition.

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Complementary mutations in NOD1 do not all result in hyperactivation.

Understanding how single nucleotide polymorphisms (SNPs) lead to disease at a molecular level provides a starting point for improved therapeutic intervention. SNPs in the innate immune receptor nucleotide oligomerisation domain 2 (NOD2) can cause the inflammatory disorders Blau Syndrome (BS) and early onset sarcoidosis (EOS) through receptor hyperactivation. Here, we show that these polymorphisms cluster into two primary locations: the ATP/Mg²⁺-binding site and helical domain 1. Polymorphisms in these two locations may consequently dysregulate ATP hydrolysis and NOD2 autoinhibition, respectively. Complementary mutations in NOD1 did not mirror the NOD2 phenotype, which indicates that NOD1 and NOD2 are activated and regulated by distinct methods.

Early-onset sarcoidosis caused by a rare CARD15/NOD2 de novo mutation and responsive to infliximab: a case report with long-term follow-up and review of the literature

Granulomatous autoinflammatory diseases are monogenic syndromes caused by mutations in the region encoding for the nucleotide-binding domain region of the NOD2/CARD15 gene with subsequent dysregulation of the inflammatory response and formation of noncaseous granulomas. They include Blau syndrome (BS) and early-onset sarcoidosis (EOS); both are clinically and genetically indistinguishable between them and they are the familial (autosomal dominantly inherited) and sporadic forms of the same disease, respectively. We describe a case of EOS, misdiagnosed for 30 years such as "juvenile rheumatoid arthritis" before and "classic sarcoidosis" later. In our patient, we found a new de novo mutation (E383G) in NOD2 that has been reported only in a family of Japanese patients with BS. After long-term follow-up (42 months), infliximab maintained good efficacy and safety without any sign of disease relapse and side effects.