Calcineurin inhibitors exacerbate coronary arteritis via the MyD88 signalling pathway in a murine model of Kawasaki disease

Protein phosphatases in TLR signaling

Toll-like receptors (TLRs) are critical sensors for the detection of potentially harmful microbes. They are instrumental in initiating innate and adaptive immune responses against pathogenic organisms. However, exaggerated activation of TLR receptor signaling can also be responsible for the onset of autoimmune and inflammatory diseases. While positive regulators of TLR signaling, such as protein serine/threonine kinases, have been studied intensively, only little is known about phosphatases, which counterbalance and limit TLR signaling. In this review, we summarize protein phosphorylation events and their roles in the TLR pathway and highlight the involvement of protein phosphatases as negative regulators at specific steps along the TLR-initiated signaling cascade. Then, we focus on individual phosphatase families, specify the function of individual enzymes in TLR signaling in more detail and give perspectives for future research. A better understanding of phosphatase-mediated regulation of TLR signaling could provide novel access points to mitigate excessive immune activation and to modulate innate immune signaling.

Previous antibiotic use and the development of Kawasaki disease: a matched pair case-control study

BACKGROUND

Kawasaki disease (KD) is an acute febrile illness with systemic vasculitides, mostly affecting infants and young children. The etiology of KD is still unclear; however, altered gut microbiota have been recently implicated as a contributing factor for the development of vasculitis.

METHODS

We conducted an age- and gender-matched case-control study on 50 patients and 200 control subjects to search for potential factors leading to intestinal dysbiosis associated with KD. Data were analyzed using conditional multivariable logistic regression.

RESULTS

Previous antibiotic administration was associated with the patients who developed KD (odds ratio [OR] 11.7, 95% confidence interval [CI] 4.7-29.1, P < 0.0001), but not other variables, including breastfeeding and group nursery. In subgroup analyses, cesarean birth was indicated as an associated factor in addition to previous antibiotic administration in infants under 12 months of age (OR: 8.0, 95% CI: 1.8-34.4, P = 0.005), but not in older children.

CONCLUSIONS

The association between previous antibiotic administration and the onset of KD was demonstrated. Antibiotics may contribute to the development of KD by affecting the intestinal microbiota in infants and young children.

Risk factors and appropriate therapeutic strategies for thrombotic microangiopathy after allogeneic HSCT

Transplant-associated thrombotic microangiopathy (TA-TMA) is a fatal complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, so far, no large cohort study determined the risk factors and the most effective therapeutic strategies for TA-TMA. Thus, the present study aimed to clarify these clinical aspects based on a large multicenter cohort. This retrospective cohort study was performed by the Kyoto Stem Cell Transplantation Group (KSCTG). A total of 2425 patients were enrolled from 14 institutions. All patients were aged ≥16 years, presented with hematological diseases, and received allo-HSCT after the year 2000. TA-TMA was observed in 121 patients (5.0%) on day 35 (median) and was clearly correlated with inferior overall survival (OS) (hazard ratio [HR], 4.93). Pre- and post-HSCT statistically significant risk factors identified by multivariate analyses included poorer performance status (HR, 1.69), HLA mismatch (HR, 2.17), acute graft-versus-host disease (aGVHD; grades 3-4) (HR, 4.02), Aspergillus infection (HR, 2.29), and veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS; HR, 4.47). The response rate and OS significantly better with the continuation or careful reduction of calcineurin inhibitors (CNI) than the conventional treatment strategy of switching from CNI to corticosteroids (response rate, 64.7% vs 20.0%). In summary, we identified the risk factors and the most appropriate therapeutic strategies for TA-TMA. The described treatment strategy could improve the outcomes of patients with TA-TMA in the future.

Kawasaki disease: pathophysiology and insights from mouse models

Kawasaki disease is an acute febrile illness and systemic vasculitis of unknown aetiology that predominantly afflicts young children, causes coronary artery aneurysms and can result in long-term cardiovascular sequelae. Kawasaki disease is the leading cause of acquired heart disease among children in the USA. Coronary artery aneurysms develop in some untreated children with Kawasaki disease, leading to ischaemic heart disease and myocardial infarction. Although intravenous immunoglobulin (IVIG) treatment reduces the risk of development of coronary artery aneurysms, some children have IVIG-resistant Kawasaki disease and are at increased risk of developing coronary artery damage. In addition, the lack of specific diagnostic tests and biomarkers for Kawasaki disease make early diagnosis and treatment challenging. The use of experimental mouse models of Kawasaki disease vasculitis has considerably improved our understanding of the pathology of the disease and helped characterize the cellular and molecular immune mechanisms contributing to cardiovascular complications, in turn leading to the development of innovative therapeutic approaches. Here, we outline the pathophysiology of Kawasaki disease and summarize and discuss the progress gained from experimental mouse models and their potential therapeutic translation to human disease.

This Review outlines the pathophysiology of Kawasaki disease and discusses the progress gained from experimental mouse models and their potential therapeutic translation to human disease.

Kawasaki disease is a childhood systemic vasculitis leading to the development of coronary artery aneurysms; it is the leading cause of acquired heart disease in children in developed countries.

The cause of Kawasaki disease is unknown, although it is suspected to be triggered by an unidentified infectious pathogen in genetically predisposed children.

Kawasaki disease might not be a normal immune response to an unusual environmental stimulus, but rather a genetically determined unusual and uncontrolled immune response to a common stimulus.

Although the aetiological agent in humans is unknown, mouse models of Kawasaki disease vasculitis demonstrate similar pathological features and have substantially accelerated discoveries in the field.

Genetic and transcriptomic analysis of blood samples from patients with Kawasaki disease and experimental evidence generated using mouse models have demonstrated the critical role of IL-1β in the pathogenesis of this disease and the therapeutic potential of targeting this pathway (currently under investigation in clinical trials).

Lipidomics links oxidized phosphatidylcholines and coronary arteritis in Kawasaki disease

AIMS

Coronary arteritis is a life-threatening complication that may arise in the acute stage of Kawasaki disease (KD), the leading cause of systemic vasculitis in childhood. Various microorganisms and molecular pathogens have been reported to cause KD. However, little is known about the key molecules that contribute to the development of coronary arteritis in KD.

METHODS AND RESULTS

To identify causative molecules for coronary arteritis in KD, we prospectively recruited 105 patients with KD and 65 disease controls in four different parts of Japan from 2015 to 2018. During this period, we conducted lipidomics analyses of their sera using liquid chromatography-mass spectrometry (LC-MS). The comprehensive LC-MS system detected a total of 27 776 molecules harbouring the unique retention time and m/z values. In the first cohort of 57 KD patients, we found that a fraction of these molecules showed enrichment patterns that varied with the sampling region and season. Among them, 28 molecules were recurrently identified in KD patients but not in controls. The second and third cohorts of 48 more patients with KD revealed that these molecules were correlated with inflammatory markers (leucocyte counts and C-reactive proteins) in the acute stage. Notably, two of these molecules (m/z values: 822.55 and 834.59) were significantly associated with the development of coronary arteritis in the acute stage of KD. Their fragmentation patterns in the tandem MS/MS analysis were consistent with those of oxidized phosphatidylcholines (PCs). Further LC-MS/MS analysis supported the concept that reactive oxygen species caused the non-selective oxidization of PCs in KD patients. In addition, the concentrations of LOX-1 ligand containing apolipoprotein B in the plasma of KD patients were significantly higher than in controls.

CONCLUSION

These data suggest that inflammatory signals activated by oxidized phospholipids are involved in the pathogenesis of coronary arteritis in KD. Because the present study recruited only Japanese patients, further examinations are required to determine whether oxidized PCs might be useful biomarkers for the development of coronary arteritis in broad populations of KD.

Refractory Kawasaki disease: diagnostic and management challenges

Kawasaki disease (KD), an acute, self-limiting, medium-sized arterial vasculitis, is now the most common cause of acquired heart disease in childhood in the developed world. In this review, we discuss the diagnosis of KD, predicting resistance to traditional therapy and treatment options in refractory or high-risk disease. We also highlight ongoing clinical trials and other potential avenues of research which may prove beneficial in managing children, especially those with resistant KD.

Kawasaki Disease

Kawasaki disease (KD) is an acute-onset systemic vasculitis of medium-sized vessels that mostly affects infants and toddlers. Globally, it is the most common form of childhood primary vasculitis. Delayed diagnosis and treatment results in coronary artery aneurysms in up to 25% of all affected individuals. Thus, KD is the most common acquired heart disease in developed countries. Here, the current understanding of clinical presentations, pathophysiological concepts, disease-associated complications, and available pharmaceutical treatment is provided and discussed in the context of available literature.