Inositol-Triphosphate 3-Kinase C and DNA Methylation Involvement in NLRP3 Inflammasome Activation in Kawasaki Disease

Vasculitis and the NLRP3 inflammasome

PURPOSE OF REVIEW

Vasculitis are a group of heterogeneous conditions characterized by chronic inflammation of blood vessels, leading to tissue destruction and organ failure. Vasculitis is an inflammatory process in which immune effector cells infiltrate blood vessels and surrounding tissues. The involvement of inflammasomes seems to occur during inflammatory processes.

RECENT FINDINGS

Studies have emphasized that genetic susceptibility is an important aspect of the pathogenesis of vasculitis. The innate immune system is a major contributor to these inflammatory diseases, suggesting that the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome plays a key role. NLRP3 activation causes the assembly of a large multiprotein and leads to the secretion of bioactive interleukin (IL)-1β and IL-18 as well as the induction of inflammatory cell death, termed pyroptosis. Accumulating evidence confirms the involvement of this cascade in sterile inflammatory diseases and other vascular diseases.

SUMMARY

In this review, we will summarize the current state of knowledge regarding the role of NLRP3 inflammasome in vascular diseases, and discuss the potential of the NLRP3 inflammasome as a therapeutic target.

Kawasaki Disease-Associated Cytokine Storm Syndrome

Kawasaki disease (KD) is a hyperinflammatory syndrome manifesting as an acute systemic vasculitis characterized by fever, nonsuppurative conjunctival injection, rash, oral mucositis, extremity changes, and cervical lymphadenopathy. KD predominantly affects young children and shares clinical features and immunobiology with other hyperinflammation syndromes including systemic juvenile idiopathic arthritis (sJIA) and multisystem inflammatory syndrome in children (MIS-C). Cytokine storm syndrome (CSS) is an acute complication in ~2% of KD patients; however, the incidence is likely underestimated as many clinical and laboratory features of both diseases overlap. CSS should be entertained when a child with KD is unresponsive to IVIG therapy with recalcitrant fever. Early recognition and prompt institution of immunomodulatory treatment can substantially reduce the mortality and morbidity of CSS in KD. Given the known pathogenetic role of IL-1β in both syndromes, the early use of IL-1 blockers in refractory KD with CSS deserves consideration.

Intravenous Immunoglobulin in Kawasaki Disease-Evolution and Pathogenic Mechanisms

Kawasaki disease (KD) is an acute vasculitis of childhood that affects the medium vessels with a special predilection to the involvement of coronary arteries. The major morbidity of this disease is due to coronary artery aneurysm, which occurs in about 25-30% of untreated cases. For decades now, intravenous immunoglobulin (IVIg) has consistently been shown to reduce the risk of CAAs to less than 5%. However, the mechanism of immunomodulation remains unclear. Several studies on the role of IVIg in the modulation of toll-like receptor pathways, autophagy, and apoptosis of the mononuclear phagocytic system, neutrophil extracellular trap, and dendritic cell modulation suggest a modulatory effect on the innate immune system. Similarly, certain studies have shown its effect on T-cell differentiation, cytokine release, and regulatory T-cell function. In this review, we discuss the potential mechanisms underlying the immunomodulatory actions of IVIg in patients with Kawasaki disease. Furthermore, we provide a summary of the evidence regarding various infusion protocols and dosages utilized in the treatment of KD patients.

ITPKC polymorphism (rs7251246 T > C), coronary artery aneurysms, and thrombosis in patients with Kawasaki disease in a Southern Han Chinese population

Objectives

Kawasaki disease (KD) is a commonly acquired pediatric systemic vasculitis disease resulting in coronary artery aneurysm (CAA). The relationship between the ITPKC polymorphism (rs7251246) and the severity and susceptibility to KD in the Han Chinese population in Southern China remains unclear.

Methods

We enrolled 262 children as controls and 221 children with KD (46 [20.8%] with intravenous immunoglobulin resistance and 82 [37.1%] with CAA). The relationship between the ITPKC rs7251246 polymorphism, KD susceptibility, and CAA formation was investigated.

Results

While the ITPKC rs7251246 T>C polymorphism was not significantly associated with KD susceptibility, it was significantly related to the CAA risk in children with KD [CC/CT vs. TT: adjusted odds ratio [OR] 2.089, 95% confidence interval [CI] 1.085-4.020]. Male children with the rs7251246 CT/TT genotype had a significantly lower risk of thrombosis [CT/TT vs. CC: adjusted OR 0.251, 95% CI 0.068-0.923]. Children with KD, especially those with CAA, had significantly downregulated ITPKC mRNA compared to healthy children. ITPKC mRNA levels were lower in children with CAA who developed thrombosis (P=0.039). In children with KD, the CC genotype showed lower mRNA levels of ITPKC (P=0.035).

Conclusion

The ITPKC rs7251246 T>C polymorphism may be a risk factor for CAA and thrombosis in children with KD in the Han Chinese population, likely due to differences in mature mRNA levels caused by interference of RNA splicing. Dual antiplatelet therapy for thrombosis is recommended for male children with the rs7251246 CC genotype.

From Co-Infections to Autoimmune Disease via Hyperactivated Innate Immunity: COVID-19 Autoimmune Coagulopathies, Autoimmune Myocarditis and Multisystem Inflammatory Syndrome in Children

Neutrophilia and the production of neutrophil extracellular traps (NETs) are two of many measures of increased inflammation in severe COVID-19 that also accompany its autoimmune complications, including coagulopathies, myocarditis and multisystem inflammatory syndrome in children (MIS-C). This paper integrates currently disparate measures of innate hyperactivation in severe COVID-19 and its autoimmune complications, and relates these to SARS-CoV-2 activation of innate immunity. Aggregated data include activation of Toll-like receptors (TLRs), nucleotide-binding oligomerization domain (NOD) receptors, NOD leucine-rich repeat and pyrin-domain-containing receptors (NLRPs), retinoic acid-inducible gene I (RIG-I) and melanoma-differentiation-associated gene 5 (MDA-5). SARS-CoV-2 mainly activates the virus-associated innate receptors TLR3, TLR7, TLR8, NLRP3, RIG-1 and MDA-5. Severe COVID-19, however, is characterized by additional activation of TLR1, TLR2, TLR4, TLR5, TLR6, NOD1 and NOD2, which are primarily responsive to bacterial antigens. The innate activation patterns in autoimmune coagulopathies, myocarditis and Kawasaki disease, or MIS-C, mimic those of severe COVID-19 rather than SARS-CoV-2 alone suggesting that autoimmunity follows combined SARS-CoV-2-bacterial infections. Viral and bacterial receptors are known to synergize to produce the increased inflammation required to support autoimmune disease pathology. Additional studies demonstrate that anti-bacterial antibodies are also required to account for known autoantigen targets in COVID-19 autoimmune complications.