Mutation screening of the CARD15 gene in sarcoidosis

A novel mutation in early-onset sarcoidosis/Blau syndrome: an association with Propionibacterium acnes

BACKGROUND

Early-onset sarcoidosis (EOS) and Blau syndrome (BS) are systemic inflammatory granulomatous diseases without visible pulmonary involvement, and are distinguishable from their sporadic and familial forms. The diseases are characterized by a triad of skin rashes, symmetrical polyarthritis, and recurrent uveitis. The most common morbidity is ocular involvement, which is usually refractory to conventional treatment. A gain-of-function mutation in the nucleotide-binding oligomerization domain-containing protein 2 (NOD2) gene has been demonstrated in this disease; however, little is known about the relationship between the activation of NOD2 and the pathophysiology of EOS/BS. Here we describe EOS/BS with a novel mutation in the NOD2 gene, as well as detection of Propionibacterium acnes (P. acnes) in the granulomatous inflammation.

CASE PRESENTATION

An 8-year-old Japanese girl presented with refractory bilateral granulomatous panuveitis. Although no joint involvement was evident, she exhibited skin lesions on her legs; a skin biopsy revealed granulomatous dermatitis, and P. acnes was detected within the sarcoid granulomas by immunohistochemistry with P. acnes-specific monoclonal (PAB) antibody. Genetic analyses revealed that the patient had a NOD2 heterozygous D512V mutation that was novel and not present in either of her parents. The mutant NOD2 showed a similar activation pattern to EOS/BS, thus confirming her diagnosis. After starting oral prednisolone treatment, she experienced an anterior vitreous opacity relapse despite gradual prednisolone tapering; oral methotrexate was subsequently administered, and the patient responded positively.

CONCLUSIONS

We presented a case of EOS/BS with a novel D512V mutation in the NOD2 gene. In refractory granulomatous panuveitis cases without any joint involvement, EOS/BS should be considered as a differential diagnosis; genetic analyses would lead to a definite diagnosis. Moreover, this is the first report of P. acnes demonstrated in granulomas of EOS/BS. Since intracellular P. acnes activates nuclear factor-kappa B in a NOD2-dependent manner, we hypothesized that the mechanism of granuloma formation in EOS/BS may be the result of NOD2 activity in the presence of the ligand muramyl dipeptide, which is a component of P. acnes. These results indicate that recognition of P. acnes through mutant NOD2 is the etiology in this patient with EOS/BS.

Ocular Sarcoidosis

Sarcoidosis is one of the leading causes of inflammatory eye disease. Any part of the eye and its adnexal tissues can be involved. Uveitis and optic neuropathy are the main manifestations, which may require systemic treatment. Two groups of patients with sarcoid uveitis can be distinguished: one of either sex and any ethnicity in which ophthalmological findings are various and another group of elderly Caucasian women with mostly chronic posterior uveitis. Clinically isolated uveitis revealing sarcoidosis remains a strictly ocular condition in a large majority of cases. Although it can be a serious condition involving functional prognosis, early recognition in addition to a growing therapeutic arsenal (including intravitreal implant) has improved the visual prognosis of the disease in recent years. Systemic corticosteroids are indicated when uveitis does not respond to topical corticosteroids or when there is bilateral posterior involvement, especially macular edema. In up to 30% of the cases that require an unacceptable dosage of corticosteroids to maintain remission, additional immunosuppression is used, especially methotrexate. As with other forms of severe noninfectious uveitis, monoclonal antibodies against tumor necrosis factor-α have been used. However, only very rarely does sarcoid uveitis fail to respond to combined corticosteroids and methotrexate therapy, a situation that should suggest either poor adherence or another granulomatous disease. Optic neuropathy often affects women of African and Caribbean origins. Some authors recommend that patients should be treated with high-dose of corticosteroids and concurrent immunosuppression from the onset of this manifestation, which is associated with a poorer outcome.

Bronchiolitis obliterans after allogeneic hematopoietic stem cell transplantation: The effect of NOD2/CARD15 mutations in a Tunisian population

Bronchiolitis obliterans (BO) is a serious lung complication that can develop after allogenic stem cell transplantation. It has been suggested that single nucleotide polymorphisms (SNPs) that affect the NOD2/CARD15 gene impair its function and result in an uncontrolled innate immune response in the recipient, thereby leading to BO. One hundred eighty-one donor-recipient pairs were analyzed for the association between NOD2 gene variants (SNP8 [Arg702Trp], SNP12 [Gly908Arg], and SNP13 [Leu1007fsinsC]) and the occurrence of BO. Ten patients (2.8%) developed this complication. The incidence of BO increases in recipient variant patient group from 4.7% to 23% in donor Wild-type group in SNP8 (p < 0.001). The incidence rose to 19% when the recipient carried the SNP12 variant (p < 0.001) in the Tunisian population. Analyses demonstrated that recipient NOD2CARD15 variants (SNP8 and SNP12) present a greater risk in developing BO than recipients without mutation. Our study demonstrated that NOD2/CARD15 typing may be useful in identifying patients at high risk for BO.

NOD2/CARD15 gene polymorphisms and sarcoidosis susceptibility: review and meta-analysis

Background: The association between NOD2/CARD15 (nucleotide binding oligomerisation domain containing 2) gene polymorphisms and susceptibility to sarcoidosis have been extensively investigated in recent years. However, the results from previous studies remain controversial. To assess the association of NOD2/CARD15 polymorphisms and sarcoidosis susceptibility, we performed a meta-analysis. Methods: PubMed, Embase, CNKI and Wanfang databases were examined for all relevant studies up until 8^th October 2016. In all, 968 cases and 1549 controls in eight case-control studies were included which mainly consisted of Caucasian participants. The relevant data were extracted and the odds ratio (OR) with 95% confidence intervals (95% CI) calculated to assess the strength of any associations. Statistical analyses were calculated using STATA12.0 software and Revman5.3 software. The associations between NOD2/CARD15 SNP rs2066844, rs2066845, rs2066847, rs1861759 polymorphisms and the risk of sarcoidosis were evaluated in allelic, dominant, recessive and additive models. Results: The pooled data showed that the NOD2/CARD15 rs2066845 polymorphism was associated with sarcoidosis susceptibility in allelic model (C vs. G, OR=1.86, 95% CI: 1.14-3.04, P=0.01), dominant model (GC + CC vs. GG, OR=1.84, 95% CI: 1.11-3.05, P=0.02) and additive model (GC vs. GG, OR=1.79, 95% CI: 1.08-2.97, P=0.02). However, the results suggested that the rs2066844, rs2066847 and rs1861759 polymorphisms might not be associated with a risk of sarcoidosis. Conclusions: This meta-analysis indicated that the 'C' allele of SNP rs2066845 may be a risk factor for sarcoidosis, especially in Caucasians, whilst rs2066844, rs2066847 and rs1861759 may not be associated with a risk of developing sarcoidosis. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 115-122).

The different roles of innate immune receptors in inflammation and carcinogenesis between races

Innate immune factors exert widespread effects on cytokine secretion, cell survival, autophagy, and apoptosis. Nucleotide-binding and oligomerization domain-like receptors (NLRs) are members of the innate immune system in the cytosol that sense pathogens, endogenous danger molecules such as uric acid, and pollutants. Nucleotide-binding oligomerization domain-containing protein 1 and 2 (NOD1 and NOD2) are components of NLR family, and ligands of these factors are γ-D-glutamyl-meso-diaminopimelic acid (iE-DAP) and muramyl dipeptide (MDP), respectively. Upon recognition of ligands, NOD1 and NOD2 induce the production of inflammatory cytokines and transcription factors including interleukin-6 (IL-6) and nuclear factor-κB (NF-κB). We examined the function of NOD1 and NOD2 in innate immunity, with a focus on their differing roles in disease pathogenesis between Japanese and Caucasian populations. Susceptibility to several immune-related diseases, including Crohn's disease, colorectal and breast cancers, and graft-versus-host-disease (GVHD) showed a correlation with genetic variants of NOD2 in Caucasian, but not in Japanese, populations. This difference may be primarily due to the fact that three major NOD2 SNPs (R702W, G908R, L1007insC) prevalent in Caucasians are rare or absent in Japanese populations. Because NLR has diverse effects on immune function, it is possible that many as yet uncharacterized immune-related diseases will also show different susceptibilities between races due to the different ratio of genetic variants in innate immune genes.

Etiologies of Sarcoidosis

Since sarcoidosis was first described more than a century ago, the etiologic determinants causing this disease remain uncertain. Studies suggest that genetic, host immunologic, and environmental factors interact together to cause sarcoidosis. Immunologic characteristics of sarcoidosis include non-caseating granulomas, enhanced local expression of T helper-1 (and often Th17) cytokines and chemokines, dysfunctional regulatory T-cell responses, dysregulated Toll-like receptor signaling, and oligoclonal expansion of CD4+ T cells consistent with chronic antigenic stimulation. Multiple environmental agents have been suggested to cause sarcoidosis. Studies from several groups implicate mycobacterial or propionibacterial organisms in the etiology of sarcoidosis based on tissue analyses and immunologic responses in sarcoidosis patients. Despite these studies, there is no consensus on the nature of a microbial pathogenesis of sarcoidosis. Some groups postulate sarcoidosis is caused by an active viable replicating infection while other groups contend there is no clinical, pathologic, or microbiologic evidence for such a pathogenic mechanism. The authors posit a novel hypothesis that proposes that sarcoidosis is triggered by a hyperimmune Th1 response to pathogenic microbial and tissue antigens associated with the aberrant aggregation of serum amyloid A within granulomas, which promotes progressive chronic granulomatous inflammation in the absence of ongoing infection.

Nucleotide-binding oligomerization domain containing 2: structure, function, and diseases

OBJECTIVES

To systematically review literature about the structure and function of nucleotide-binding oligomerization domain containing 2 (NOD2) and its disease association.

METHODS

The English literature was searched using keywords "NOD2" and "disease". Relevant original and review articles were reviewed.

RESULTS

NOD2 is an intracellular protein and shares similar molecular structure with NOD1, pyrin, and cryopyrin. There are more than 100 NOD2 gene mutations, some of which have been linked to diseases such as Crohn disease, Blau syndrome, and NOD2-associated autoinflammatory disease (NAID). The NOD2 variants located in the leucine-rich repeat (LRR) region are susceptible to Crohn disease, and the variants in the nucleotide-binding domain (NBD) and in between the NBD and LRR are associated with Blau syndrome and NAID, respectively. No disease association with the gene variants has been found in rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis, psoriasis/psoriatic arthritis, adult sarcoidosis, granulomatous polyangiitis, or multiple sclerosis. The potential association of the NOD2 variants with graft-versus-host-disease remains controversial. NOD2 functions mainly through RICK or RIP2 to activate p38 mitogen-activated protein kinases and NF-κB, resulting in inflammatory response, and enhanced autophagic activity. Biologic therapy may be beneficial for NOD2-associated diseases, and new drug development may be realized based upon the signaling pathways.

CONCLUSIONS

NOD2 gene mutations are associated with several diseases, and some of the mutations are of diagnostic value in Blau disease and NAID. To understand the NOD2 function, disease association, and its pathogenesis is important given the ever increasing clinical significance of NOD2.