Lethal and severe coronary arteritis in DBA/2 mice induced by fungal pathogen, CAWS, Candida albicans water-soluble fraction

mTOR signalling controls the formation of smooth muscle cell-derived luminal myofibroblasts during vasculitis

The accumulation of myofibroblasts within the intimal layer of inflamed blood vessels is a potentially catastrophic complication of vasculitis, which can lead to arterial stenosis and ischaemia. In this study, we have investigated how these luminal myofibroblasts develop during Kawasaki disease (KD), a paediatric vasculitis typically involving the coronary arteries. By performing lineage tracing studies in a murine model of KD, we reveal that luminal myofibroblasts develop independently of adventitial fibroblasts and endothelial cells, and instead derive from smooth muscle cells (SMCs). Notably, the emergence of SMC-derived luminal myofibroblasts-in both mice and patients with KD, Takayasu's arteritis and Giant Cell arteritis-coincided with activation of the mechanistic target of rapamycin (mTOR) signalling pathway. Moreover, SMC-specific deletion of mTOR signalling, or pharmacological inhibition, abrogated the emergence of luminal myofibroblasts. Thus, mTOR is an intrinsic and essential regulator of luminal myofibroblast formation that is activated in vasculitis patients and therapeutically tractable. These findings provide molecular insight into the pathogenesis of coronary artery stenosis and identify mTOR as a therapeutic target in vasculitis.

Statin suppresses the development of excessive intimal proliferation in a Kawasaki disease mouse model

Kawasaki disease (KD) causes vascular injury and lifelong remodeling. Excessive intimal proliferation has been observed, resulting in coronary artery lesions (CALs). However, the mechanisms underlying vascular remodeling in CAL and statin treatment have not been comprehensively elucidated. This study aimed to investigate the effects of statins on vascular remodeling using a KD mouse model. Candida albicans water-soluble substance (CAWS) was intraperitoneally injected in 5-week-old male apolipoprotein-E-deficient mice. They were categorized as follows (n = 4): control, CAWS, CAWS+statin, and late-statin groups. The mice were euthanized at 6 or 10 weeks after injection. Statins (atorvastatin) were initiated after CAWS injection, except for the late-statin group, for which statins were internally administered 6 weeks after injection. Elastica van Gieson staining and immunostaining were performed for evaluation. Statins substantially suppressed the marked neointimal hyperplasia induced by CAWS. Additionally, CAWS induced TGFβ receptor II and MAC-2 expression around the coronary arteries, which was suppressed by the statins. KD-like vasculitis might promote the formation of aneurysm by destroying elastic laminae and inducing vascular stenosis by neointimal proliferation. The anti-inflammatory effects of statins might inhibit neointimal proliferation. Therefore, statin therapy might be effective in adult patients with KD with CAL by inhibiting vascular remodeling.

Mechanistic Target of Rapamycin Inhibition Prevents Coronary Artery Remodeling in a Murine Model of Kawasaki Disease

OBJECTIVE

Remodeling of the coronary arteries is a common feature in severe cases of Kawasaki disease (KD). This pathology is driven by the dysregulated proliferation of vascular fibroblasts, which can lead to coronary artery aneurysms, stenosis, and myocardial ischemia. We undertook this study to investigate whether inhibiting fibroblast proliferation might be an effective therapeutic strategy to prevent coronary artery remodeling in KD.

METHOD

We used a murine model of KD (induced by the injection of the Candida albicans water-soluble complex [CAWS]) and analyzed patient samples to evaluate potential antifibrotic therapies for KD.

RESULTS

We identified the mechanistic target of rapamycin (mTOR) pathway as a potential therapeutic target in KD. The mTOR inhibitor rapamycin potently inhibited cardiac fibroblast proliferation in vitro, and vascular fibroblasts up-regulated mTOR kinase signaling in vivo in the CAWS mouse model of KD. We evaluated the in vivo efficacy of mTOR inhibition and found that the therapeutic administration of rapamycin reduced vascular fibrosis and intimal hyperplasia of the coronary arteries in CAWS-injected mice. Furthermore, the analysis of cardiac tissue from KD fatalities revealed that vascular fibroblasts localizing with inflamed coronary arteries up-regulate mTOR signaling, confirming that the mTOR pathway is active in human KD.

CONCLUSION

Our findings demonstrate that mTOR signaling contributes to coronary artery remodeling in KD, and that targeting this pathway offers a potential therapeutic strategy to prevent or restrict this pathology in high-risk KD patients.

Intimal macrophages develop from circulating monocytes during vasculitis

Objective

Vasculitis is characterised by inflammation of the blood vessels. While all layers of the vessel can be affected, inflammation within the intimal layer can trigger thrombosis and arterial occlusion and is therefore of particular clinical concern. Given this pathological role, we have examined how intimal inflammation develops by exploring which (and how) macrophages come to populate this normally immune‐privileged site during vasculitis.

Methods

We have addressed this question for Kawasaki disease (KD), which is a type of vasculitis in children that typically involves the coronary arteries. We used confocal microscopy and flow cytometry to characterise the macrophages that populate the coronary artery intima in KD patient samples and in a mouse model of KD, and furthermore, have applied an adoptive transfer system to trace how these intimal macrophages develop.

Results

In KD patients, intimal hyperplasia coincided with marked macrophage infiltration of the coronary artery intima. Phenotypic analysis revealed that these ‘intimal macrophages’ did not express markers of resident cardiac macrophages, such as Lyve‐1, and instead, were uniformly positive for the chemokine receptor Ccr2, suggesting a monocytic lineage. In support of this origin, we show that circulating monocytes directly invade the intima via transluminal migration during established disease, coinciding with the activation of endothelial cells lining the coronary arteries.

Conclusions

During KD, intimal macrophages develop from circulating monocytes that infiltrate the inflamed coronary artery intima by transluminal migration.

Kawasaki Disease-like Vasculitis Facilitates Atherosclerosis, and Statin Shows a Significant Antiatherosclerosis and Anti-Inflammatory Effect in a Kawasaki Disease Model Mouse

Kawasaki disease (KD) is an acute form of systemic vasculitis that may promote atherosclerosis in adulthood. This study examined the relationships between KD, atherosclerosis, and the long-term effects of HMG-CoA inhibitors (statins). Candida albicans water-soluble fraction (CAWS) was injected intraperitoneally into 5-week-old male apolipoprotein-E-deficient (Apo E-/-) mice to create KD-like vasculitis. Mice were divided into 4 groups: the control, CAWS, CAWS+statin, and late-statin groups. They were sacrificed at 6 or 10 weeks after injection. Statin was started after CAWS injection in all groups except the late-statin group, which was administered statin internally 6 weeks after injection. Lipid plaque lesions on the aorta were evaluated with Oil Red O. The aortic root and abdominal aorta were evaluated with hematoxylin and eosin staining and immunostaining. CAWS vasculitis significantly enhanced aortic atherosclerosis and inflammatory cell invasion into the aortic root and abdominal aorta. Statins significantly inhibited atherosclerosis and inflammatory cell invasion, including macrophages. CAWS vasculitis, a KD-like vasculitis, promoted atherosclerosis in Apo E-/- mice. The long-term oral administration of statin significantly suppressed not only atherosclerosis but also inflammatory cell infiltration. Therefore, statin treatment may be used for the secondary prevention of cardiovascular events during the chronic phase of KD.

Sivelestat's effect on Candida albicans water-soluble fraction-induced vasculitis

BACKGROUND

We investigated the efficacy of sivelestat sodium hydrate (SSH) as a treatment for Kawasaki disease, and its pharmacological action sites, in mice with Candida albicans water-soluble fraction-induced vasculitis.

METHODS

Sivelestat sodium hydrate was administered intraperitoneally to Candida albicans water-soluble fraction-induced vasculitis model mice to assess its efficacy in preventing the development of coronary artery lesions based on the degree of inflammatory cell infiltration in the aortic root and coronary arteries (vasculitis score). The pharmacological sites of action were investigated based on changes in neutrophil elastase (NE) and intercellular adhesion molecule 1 (ICAM-1) positive areas, ICAM-1 and tumor necrosis factor-α mRNA expression levels in the upper heart, and the proportion of monocytes in the peripheral blood.

RESULTS

The vasculitis score decreased below the lower limit of the 95% confidence interval of untreated mice in 69% of the SSH-treated mice. The NE- and ICAM-1-positive regions, and the mRNA expression of ICAM-1 and tumor necrosis factor-α were lower in the SSH-treated mice than in the untreated mice. The proportion of monocytes in the peripheral blood was higher in the SSH-treated mice than in the untreated mice, whereas monocyte migration to inflammation areas was suppressed in the SSH-treated mice.

CONCLUSIONS

Our results showed that SSH might prevent the development of coronary artery lesions and ameliorate disease activity. In addition to its NE-inhibitory effect, SSH sites of action may also include monocytes.

Candida albicans Induces Foaming and Inflammation in Macrophages through FABP4: Its Implication for Atherosclerosis

Atherosclerosis is a chronic degenerative disorder characterized by lipid-dense plaques and low-grade inflammation affecting arterial walls. Foamy macrophages are important in the formation of atherosclerotic plaques and the induction of low-grade inflammation. The presence of lipid-laden macrophages has occurred in infections caused by opportunistic pathogens. Candida albicans is the major cause of candidiasis in immunocompromised patients, including those with diabetes mellitus. However, the role played by C. albicans in macrophage foaming and the associated inflammation is poorly understood. We investigated whether C. albicans induces foaming along with inflammation in macrophages and, if so, by which mechanism(s). We incubated THP-1 macrophages with heat-killed C. albicans (HKCA). HKCA-induced lipid accumulation in macrophages along with increased expression of inflammatory markers, including CD11b and CD11c or expression and secretion of IL-1β. HKCA also increased the expression of PPARγ, CD36, and FABP4 in macrophages. Mechanistically, we found that the foamy and inflammatory macrophage phenotype induced by HKCA requires FABP4 because disruption of FABP4 in macrophages either by chemical inhibitor BMS309404 or small interfering RNA (siRNA) abrogated foam cell formation and expression of inflammatory markers CD11b, CD11c, and IL-1β. Furthermore, HKCA-treated macrophages displayed high expression and secretion of MMP-9. Inhibition of FABP4 resulted in suppression of HCKA-induced MMP-9 production. Overall, our results demonstrate that C. albicans induces foam cell formation, inflammation, and MMP-9 expression in macrophages via the upregulation of FABP4, which may constitute a novel therapeutic target for treating C. albicans-induced atherosclerosis.

The microbiome in autoimmune rheumatic disease

Microbial contributions to the immunopathogenesis of autoimmune rheumatic diseases have been studied since the advent of germ theory in the 19th century. With the exception of Group A Streptococcus in rheumatic fever, early studies failed to establish causal relationships between specific pathobionts and rheumatic disease. Today, systemic autoimmune diseases are thought to result from a complex interplay of environmental factors, individual genetic risk, and stochastic events. Interactions of microbiota and the immune system have been shown to promote and sustain chronic inflammation and autoimmunity. In mechanistic studies, microbe-immune cell interactions have been implicated in the initiation of autoimmune rheumatic diseases, e.g., through the posttranslational modification of autoantigens in rheumatoid arthritis or through neutrophil cell death and cross-reactivity with commensal orthologs in systemic lupus erythematosus. In parallel, modern molecular techniques have catalyzed the study of the microbiome in systemic autoimmune diseases. Here, I review current insights gained into the skin, oral, gut, lung, and vascular microbiome in connective tissue diseases and vasculitis. Mechanism relevant to the development and propagation of autoimmunity will be discussed whenever explored. While studies on autoimmune rheumatic disease have almost invariably shown abnormal microbiome structure (dysbiosis), substantial variability in microbial composition between studies makes generalization difficult. Moreover, an etiopathogenic role of specific pathobionts cannot be inferred by association alone. Integrating descriptive studies of microbial communities with hypothesis-driven research informed by immunopathogenesis will be important in elucidating targetable mechanisms in preclinical and established rheumatic disease.

Adipose tissue-derived stem cells suppress coronary arteritis of Kawasaki disease in vivo

BACKGROUND

Kawasaki disease (KD) is a systemic inflammatory disease resulting in an acute febrile syndrome commonly affecting children younger than 5 years. Coronary arteritis in KD is occasionally non-responsive to several treatments. Recently, adipose tissue-derived stem cells (ADSCs) have been shown to have anti-inflammatory, immunosuppressive, and tissue-repair characteristics and are considered a useful treatment for inflammatory disease. The present study aimed to elucidate whether the administration of ADSCs can suppress KD-associated vasculitis in vivo.

METHODS

Candida albicans water-soluble fraction is often used to model KD via the induction of severe coronary arteritis. Kawasaki disease model mice were intravenously administered ADSCs and phosphate-buffered saline (PBS). On day 29, the mice were sacrificed and hearts from mice in each group were dissected. This was followed by serum collection. Cardiac tissue sections were subjected to histopathological examination to evaluate the inflammatory area. The levels of pro-inflammatory cytokines in the serum were analyzed at days 15 and 29. The survival rates of both groups were compared.

RESULTS

The mean inflammatory area in coronary arteritis was significantly lower in the ADSC group compared to the PBS group (P < 0.01). Furthermore, the levels of pro-inflammatory cytokines, such as IL-1β, IL-12, IL-17, RANTES, INF-γ, and TNF-α, in the ADSC group were significantly lower than those in the PBS group. Moreover, the ADSC group had a significantly higher survival rate than the PBS group.

CONCLUSIONS

These findings highlight that ADSCs have anti-inflammatory and immune regulatory functions that could provide novel cell-based therapeutic strategies for severe KD.

Interleukin-1beta Inhibition Attenuates Vasculitis in a Mouse Model of Kawasaki Disease

BACKGROUND

Kawasaki disease (KD), a systemic vasculitis, is suspected to be related to abnormalities in innate immunity. Based on the important role of IL-1 signaling in innate immunity, we investigated the effects of an anti-IL-1β antibody using a Candida albicans water-soluble fraction (CAWS)-induced mouse model of KD.

METHODS

CAWS (0.5 mg/mouse) was injected intraperitoneally into 5-week-old DBA/2 mice on five consecutive days. An anti-Murine IL-1β antibody (01BSUR) was administered at various doses (2.5, 5.0, and 10.0 mg/kg) and time points (2 days before, same day, and 2, 5, 7, and 14 days after CAWS administration). After 4 weeks, vasculitis in the aortic root was investigated histologically. Cytokines including IL-1β, -6, -10, and TNF-α were also measured.

RESULTS

Groups administered 01BSUR at all doses showed a significant reduction in the area of vasculitis. In addition, 01BSUR inhibited vasculitis until 7 days after CAWS administration. In the analysis of various time points, the level of IL-6 was lower in all groups compared to the CAWS only group, but the levels of IL-1β, TNFα, and IL-10 were lower when 01BSUR was administered before CAWS. On the other hand, TNFα and IL-10 levels were restored when 01BSUR was administered after CAWS, suggesting that 01BSUR may have additional effects beyond blocking IL-1β signaling.

CONCLUSIONS

The anti-IL-1β antibody significantly attenuated CAWS-induced vasculitis. The mechanism of inhibiting vasculitis is thought to include inhibition of the IL-1β pathway and additional effects beyond blocking IL-1β signaling.

Effects of Natural and Chemically Defined Nutrients on Candida albicans Water-soluble Fraction (CAWS) Vasculitis in Mice

Kawasaki disease (KD) is an inflammatory disease that was identified by Professor Tomisaku Kawasaki in 1961. Candida albicans-derived substances, such as C. albicans water-soluble fraction (CAWS) , induce coronary arteritis similar to KD in mice. CAWS functions as a pathogen-associated molecular pattern (PAMP) by acting as a ligand for dectin-2. A gut-associated immunological system has developed specifically to segregate advantageous and detrimental stimuli, and the microbial flora has been found to markedly affect the development and severity of diseases. We herein investigated whether diet affects the onset and progression of CAWS vasculitis in mice. A standard diet, CE-2, and chemically defined diet, AIN93G, which is free of β-glucan, were used. Although all mice administered with CAWS died, the mean number of survival days was smaller in the AIN93G group because vasculitis was induced earlier than in the CE-2 group. Bacteroides, which are inflammatory flora, were enriched in the microbial flora of the AIN93G group. The results of the present study suggest that diet quality affects not only microbial flora changes, but also the progression of systemic disease.

Characterization of Oral Microbiota in Removable Dental Prosthesis Users: Influence of Arterial Hypertension

INTRODUCTION

Studies have described the possible relation between oral infections and atherosclerotic events.

OBJECTIVE

To characterize the oral microbiota of normotensive and hypertensive users of dental prostheses.

METHODS

The sample consisted of 41 complete dental prosthesis users, divided into groups: 21 participants with systemic arterial hypertension and 20 normotensive participants. The data collection included the characteristics of the sociodemographic variables and the determination of the microbial load in the saliva. For the descriptive analyses, Statistical Package for the Social Sciences was used. The description of the proportional differences between the groups was based on the application of Mann-Whitney's statistical test. Statistical significance was set at 5% (p < 0.05).

RESULTS

The analysis of the oral microbiota showed the vast growth of aerobic microorganisms in all samples from both groups. The microbial load of streptococci and staphylococci was significantly higher among hypertensive participants. Candida yeasts were detected in the saliva culture of most samples. The hypertensive participants rank in the category of very high colonization index/high risk of infection related to this microorganism.

CONCLUSIONS

The mouth of dental prosthesis users, especially when hypertensive, can constitute an important reservoir of pathogens, indicating an established inflammatory or infectious condition or risk for developing this condition.

Characterization of a murine model with arteritis induced by Nod1 ligand, FK565: A comparative study with a CAWS-induced model

OBJECTIVE

Kawasaki disease (KD) occurs via activation of the innate immune system. Nucleotide oligomerization domain-1 (NOD1) is a pattern recognition receptor regulating the innate immunity. We characterized histopathology of arteritis induced by FK565, a ligand for NOD1, in mice, compared with Candida albicans water-soluble fraction (CAWS)-induced model.

METHODS

Vasculitis was induced by injection of FK565 or CAWS into C57BL6/J mice (n = 9 and n = 11, respectively). At 4 weeks, they were sacrificed, and plasma cytokines and chemokines were measured.

RESULTS

FK565 injection induced vasculitis mainly involving bilateral coronary arteries whereas the aortic root was diffusely affected in CAWS mice. In FK565 animals, the abdominal aorta and its branching arteries also exhibited inflammation with atherosclerosis. IL-1α, IL-1β, IL-5 and RANTES were increased in FK565 group whereas IL-6, IL-13, G-CSF, IFN-γ, and TNF-α were higher in CAWS animals (p < .05 for all variables). The total area of inflammation in FK565 mice appeared to correlate with IL-1β levels (r = 0.71, p = .05).

CONCLUSIONS

Histopathology of FK565-induced model demonstrated 'site-specific' coronary arteritis mimicking KD. This histopathological difference from CAWS model may be due to different cytokine expression profiles.

Kawasaki disease: a matter of innate immunity

Kawasaki disease (KD) is an acute systemic vasculitis of childhood that does not have a known cause or aetiology. The epidemiological features (existence of epidemics, community outbreaks and seasonality), unique age distribution and clinical symptoms and signs of KD suggest that the disease is caused by one or more infectious environmental triggers. However, KD is not transmitted person-to-person and does not occur in clusters within households, schools or nurseries. KD is a self-limited illness that is not associated with the production of autoantibodies or the deposition of immune complexes, and it rarely recurs. Regarding the underlying pathophysiology of KD, innate immune activity (the inflammasome) is believed to play a role in the development of KD vasculitis, based on the results of studies with animal models and the clinical and laboratory findings of KD patients. Animal studies have demonstrated that innate immune pathogen-associated molecular patterns (PAMPs) can cause vasculitis independently of acquired immunity and have provided valuable insights regarding the underlying mechanisms of this phenomenon. To validate this concept, we recently searched for KD-specific PAMPs and identified such molecules with high specificity and sensitivity. These molecules have structures similar to those of microbe-associated molecular patterns (MAMPs), as shown by liquid chromatography-tandem mass spectrometry. We propose herein that KD is an innate immune disorder resulting from the exposure of a genetically predisposed individual to microbe-derived innate immune stimulants and that it is not a typical infectious disease.

GM-CSF primes cardiac inflammation in a mouse model of Kawasaki disease

Using a mouse model of Kawasaki disease, Stock and collaborators have discovered an essential role for GM-CSF as an instigator of cardiac inflammation.

Kawasaki disease (KD) is the leading cause of pediatric heart disease in developed countries. KD patients develop cardiac inflammation, characterized by an early infiltrate of neutrophils and monocytes that precipitates coronary arteritis. Although the early inflammatory processes are linked to cardiac pathology, the factors that regulate cardiac inflammation and immune cell recruitment to the heart remain obscure. In this study, using a mouse model of KD (induced by a cell wall Candida albicans water-soluble fraction [CAWS]), we identify an essential role for granulocyte/macrophage colony-stimulating factor (GM-CSF) in orchestrating these events. GM-CSF is rapidly produced by cardiac fibroblasts after CAWS challenge, precipitating cardiac inflammation. Mechanistically, GM-CSF acts upon the local macrophage compartment, driving the expression of inflammatory cytokines and chemokines, whereas therapeutically, GM-CSF blockade markedly reduces cardiac disease. Our findings describe a novel role for GM-CSF as an essential initiating cytokine in cardiac inflammation and implicate GM-CSF as a potential target for therapeutic intervention in KD.

Biology and Diseases of Mice

Today’s laboratory mouse, Mus musculus, has its origins as the ‘house mouse’ of North America and Europe. Beginning with mice bred by mouse fanciers, laboratory stocks (outbred) derived from M. musculus musculus from eastern Europe and M. m. domesticus from western Europe were developed into inbred strains. Since the mid-1980s, additional strains have been developed from Asian mice (M. m. castaneus from Thailand and M. m. molossinus from Japan) and from M. spretus which originated from the western Mediterranean region.

Tropospheric winds from northeastern China carry the etiologic agent of Kawasaki disease from its source to Japan

Evidence indicates that the densely cultivated region of northeastern China acts as a source for the wind-borne agent of Kawasaki disease (KD). KD is an acute, coronary artery vasculitis of young children, and still a medical mystery after more than 40 y. We used residence times from simulations with the flexible particle dispersion model to pinpoint the source region for KD. Simulations were generated from locations spanning Japan from days with either high or low KD incidence. The postepidemic interval (1987-2010) and the extreme epidemics (1979, 1982, and 1986) pointed to the same source region. Results suggest a very short incubation period (<24 h) from exposure, thus making an infectious agent unlikely. Sampling campaigns over Japan during the KD season detected major differences in the microbiota of the tropospheric aerosols compared with ground aerosols, with the unexpected finding of the Candida species as the dominant fungus from aloft samples (54% of all fungal strains). These results, consistent with the Candida animal model for KD, provide support for the concept and feasibility of a windborne pathogen. A fungal toxin could be pursued as a possible etiologic agent of KD, consistent with an agricultural source, a short incubation time and synchronized outbreaks. Our study suggests that the causative agent of KD is a preformed toxin or environmental agent rather than an organism requiring replication. We propose a new paradigm whereby an idiosyncratic immune response, influenced by host genetics triggered by an environmental exposure carried on winds, results in the clinical syndrome known as acute KD.

Involvement of mannose-binding lectin in the pathogenesis of Kawasaki disease-like murine vasculitis

Kawasaki disease (KD) is a paediatric idiopathic vasculitis. In this study, on the basis of studies using an established animal model for KD, we report that mannose-binding lectin (MBL) is involved in the pathogenesis of the disease. KD-like experimental murine vasculitis was induced by intraperitoneally administering a Candida albicans water-soluble extract (CAWS). MBL-A gradually increased in the serum of the model mice treated with CAWS. Deposition of MBL-A and MBL-C was observed in the aortic root, including the coronary arteries, which is a predilection site in experimental vasculitis. Corresponding to the distribution patterns of MBLs, marked deposition of C3/C3-derived peptides was also observed. Regarding the self-reactivity of MBLs, we observed that MBLs interacted with core histones to activate the lectin pathway. These results suggest that some types of pathogens provoke the MBL-dependent complement pathway (lectin pathway) to cause and/or exacerbate KD-like vasculitis.

The involvement of the vasa vasorum in the development of vasculitis in animal model of Kawasaki disease

BACKGROUND

Kawasaki Disease (KD) involves a diffuse and systemic vasculitis of unknown etiology that mainly affects infants and children. Although a considerable number of analyses of the clinical, histopathological and molecular biological details underlying the mechanism responsible for the development of coronary arterial lesions, it is still poorly understood.The purpose of this study was to analyze the state of angiogenesis, vasculogenesis and the distribution of blood vessels using an animal model of KD like vasculitis. We investigated the involvement of the vasa vasorum from the adventitia in the vascular involvement and the development of the disease state by performing sequential histopathology, scanning electron microscopy (SEM) and micro computed tomography (CT) studies using a murine model of vasculitis induced by the Candida albicans water-soluble fraction (CAWS).

METHODS

To prepare the animal model of KD like vasculitis, CAWS was intraperitoneally injected into C57BL/6N mice for five consecutive days as reported by Ohno et al. We observed the changes of the vasa vasorum at the aorta and the orifices of the coronary arteries by SEM and micro CT, and also compared the neovascularization at the media and adventitia of the aorta by an immunohistochemical analysis.

RESULTS

As previously reported, obvious inflammation was detected two weeks after the injection of CAWS, and also intimal thickening was observed three weeks after the injection. We found that the vasa vasorum in the adventitia of the aorta was increased in the model mice. The vasa vasorum started increasing one week after the injection of CAWS, before any obvious vasculitis was microscopically detected.

CONCLUSION

The present results indicate that the vasculitis in Kawasaki disease starts as a disorder of the vasa vasorum.

Trained innate immunity and atherosclerosis

PURPOSE OF REVIEW

Monocytes/macrophages play a decisive role in the development and progression of atherosclerosis. It is currently unknown what stimuli initiate and orchestrate the activation of these cells in atherogenesis. In this review, we postulate that the novel concept of 'trained immunity' modulates the development and progression of atherosclerosis.

RECENT FINDINGS

Recently, results from our laboratory challenged the current paradigm that innate immunity is static and does not have an immunological memory. Stimulation by various microbial products, including Candida albicans and bacille Calmette-Guérin, appeared to bring monocytes into a long-term enhanced functional state, showing a stronger proinflammatory response to a second stimulus. This 'trained immunity' was mediated by increased and stable histone methylation.

SUMMARY

We describe the hypothesis that this functional reprogramming of monocytes, either by microbial products or by metabolic products, contributes to atherogenesis and propose epigenetic reprogramming of monocytes as a novel pharmacological target for preventing or treating atherosclerosis in the future.

CAWS administration increases the expression of interferon γ and complement factors that lead to severe vasculitis in DBA/2 mice

Background

Candida albicans water-soluble fraction (CAWS), a mannoprotein-β-glucan complex obtained from the culture supernatant of C. albicans NBRC1385, causes CAWS-mediated vasculitis (CAWS-vasculitis) in B6 and DBA/2 mice with mild and lethal symptoms, respectively. Why CAWS is lethal only in DBA/2 mice remains unknown.

Results

We performed DNA microarray analyses using mRNA obtained from peripheral blood mononuclear cells (PBMCs) of B6 and DBA/2 mice and compared their respective transcriptomes. We found that the mRNA levels of interferon-γ (Ifng) and several genes that regulate the complement system, such as C3, C4, Cfb, Cfh, and Fcna, were increased dramatically only in DBA/2 mice at 4 and 8 weeks after CAWS administration. The dramatic increase was confirmed by quantitative real-time polymerase chain reactions (qRT-PCR). Moreover, mRNA levels of immune-related genes, such as Irf1, Irf7, Irf9, Cebpb, Ccl4, Itgam, Icam1, and IL-12rb1, whose expression levels are known to be increased by Ifng, were also increased, but only in DBA/2 mice. By contrast, the mRNA level of Dectin-2, the critical receptor for the α-mannans of CAWS, was increased slightly and similarly in both B6 and DBA/2 mice after CAWS administration.

Conclusions

Taken together, our results suggest that CAWS administration induces Dectin-2 mediated CAWS-vasculitis in both B6 and DBA/2 mice and the expression of Ifng, but only in DBA/2 mice, which led to increased expression of C3, C4, Cfb, Cfh, and Fcna and an associated increase in lethality in these mice. This model may contribute to our understanding of the pathogenesis of severe human vasculitis.

β-mannosyl linkages inhibit CAWS arteritis by negatively regulating dectin-2-dependent signaling in spleen and dendritic cells

AIMS

CAWS, Candida albicans water-soluble fraction, is an extracellular mannoprotein produced by C. albicans NBRC1385. It is a ligand of dectin-2, the C-type lectin receptor for innate immunity, and has strong potency for induction of vasculitis in DBA/2 mice. The structure of this mannoprotein is known to be modulated by the culture conditions. To clarify the structure required for vasculitis, CAWSs were prepared in the two culture conditions with or without pH control, and biological properties were compared.

METHODS

CAWSs prepared by the standard protocol and pH controlled at 7.0 were designated as CAWS and CAWS727, respectively. The antigenicity was detected by the anti-Candida mannan IgG. These chemical structures were assessed by nuclear magnetic resonance analysis and the lectin array system. The in vitro activity of CAWSs was tested by tumor necrosis factor-α (TNF-α) induction using bone marrow-derived dendritic cells and spleen cell cultures.

RESULTS

The antigenicity of CAWS727 was similar to CAWS but the nuclear magnetic resonance analysis showed a higher ratio of β-mannosyl linkages were detected in CAWS727. The lectin array showed relative affinities of CAWS727 to α-mannosyl specific lectins were weaker than those of CAWS. CAWS induced severe vasculitis in DBA/2 mice while CAWS727 did not. CAWS significantly induced TNF-α but CAWS727 did slightly. In addition, CAWS-induced TNF-α production was inhibited by mixing with CAWS727 in a concentration dependent manner.

CONCLUSION

The α-mannosyl linkages of Candida mannan is a key molecule for the immunotoxicity. CAWS727, which conatins β-mannosyl linkages, competitively bound to lectin receptors, and resulted in reductions in the inflammatory response.

Triptolide as an Alternative to IVIG Therapy for Kawasaki Disease in a Mouse Model

BACKGROUND

Kawasaki disease is treated by immunoglobulin therapy, which has adverse side effects like renal damage.

AIMS

The aim of the present study was to explore the effectiveness of triptolide, a compound derived from threewingnut that has anti-inflammatory effects, on the treatment of Kawasaki disease in a mouse model.

STUDY DESIGN

Animal experiment.

METHODS

A mouse model of Kawasaki disease was established through exposure to Candida albicans by intraperitoneal injection. Exposed mice were then randomly divided into several groups (each n=15): model group (saline-treated), low- or high-dose triptolide groups (0.2 mg/kg or 0.4 mg/kg, respectively), and IVIG (high-dose immunoglobulin) group (1 g/kg body weight). Unexposed mice served as an additional control group. Nine weeks from the initial exposure, mice were euthanised and coronary tissues and blood samples were harvested. The rate of apoptosis was detected by TUNEL, and ICAM-1 expression was detected by immunohistochemistry in coronary endothelial cells. Serum TNF-α levels were detected by ELISA.

RESULTS

Compared to mice in the (unexposed) control group, apoptosis of endothelial cells, ICAM-1 expression, and serum TNF-α levels were significantly increased in all exposed mice (p<0.05), confirming the presence of disease. However, treatment with triptolide or IVIG significantly lowered these measures compared to untreated exposed mice (model group; p<0.05).

CONCLUSIONS

Triptolide treatment reduces markers of coronary endothelial inflammation in a mouse model of Kawasaki disease, similar to IVIG treatment, and therefore may be a useful alternative therapy for this disease.

Etanercept suppresses arteritis in a murine model of kawasaki disease: a comparative study involving different biological agents

Coronary arteritis, a complication of Kawasaki disease (KD), can be refractory to immunoglobulin (IVIG) treatment. To determine the most effective alternative therapy, we compared the efficacy of different agents in a mouse model of KD. Vasculitis was induced by injection of Candida albicans water-soluble fractions (CAWS) into a DBA/2 mouse, followed by administration of IVIG, etanercept, methylprednisolone (MP), and cyclosporine-A (CsA). At 2 and 4 weeks, the mice were sacrificed, and plasma cytokines and chemokines were measured. CAWS injection induced active inflammation in the aortic root and coronary arteries. At 2 weeks, the vasculitis was reduced only by etanercept, and this effect persisted for the subsequent 2 weeks. At 4 weeks, IVIG and CsA also attenuated the inflammation, but the effect of etanercept was more significant. MP exerted no apparent effect at 2 or 4 weeks. The suppressive effect exerted by etanercept on cytokines, such as interleukin- (IL-)6, IL-12, IL-13, and tumor necrosis factor-α (TNF-α), was more evident than that of others. The extent of arteritis correlated with the plasma TNF-α levels, suggesting a pivotal role of TNF-α in KD. In conclusion, etanercept was most effective in suppressing CAWS-induced vasculitis and can be a new therapeutic intervention for KD.

[Negative regulatory factor of CAWS (Candida albicans water-soluble fraction) -vasculitis in CBA/J mice as assessed by comparison with Bruton's tyrosine kinase-deficient CBA/N mice]

Candida albicans water-soluble fraction (CAWS) has microbial pathogen-associated molecular patterns (PAMPs). It is a mannoprotein-β glucan complex obtained from the culture supernatant of Candida albicans NBRC1385 and exhibits vasculitis-inducing activity (CAWS vasculitis) in mice. The sensitivity to CAWS vasculitis varies greatly among mouse strains. This study examined the factors contributing to or inhibiting CAWS vasculitis using CAWS-vasculitis-resistant CBA/J mice and Bruton's tyrosine kinase (Btk)-deficient CBA/N mice, which is a CAWS-vasculitis-sensitive strain having the same origin as CBA/J mice. After stimulation with various kinds of pathogen-associated molecular patterns (PAMPs), the production of inflammatory cytokines IL-6 and IFN-γwas induced in CBA/N mice, whereas that of immunosuppressive IL-10 was induced in CAWS-vasculitis-resistant CBA/J mice. The production of TIMP1, an endogenous matrix metalloproteinase (MMP) inhibitor, was observed in CBA/J mice. Furthermore, the induction of CAWS-vasculitis was inhibited by gene therapy using plasmid (pCAGGS-mIL-10). The results strongly suggest that the difference in the production of these cytokines is closely linked to the development of CAWS vasculitis.

A Model of Left Ventricular Dysfunction Complicated by CAWS Arteritis in DBA/2 Mice

It was reported previously that a Candida albicans water-soluble fraction (CAWS), including a mannoprotein and β-glucan complex, has strong potency in inducing fatal necrotizing arteritis in DBA/2 mice. In this study, histopathological changes and cardiac function were investigated in this system. One mg/day of CAWS was given to DBA/2 mice via peritoneal injection for five days. The CAWS-treated DBA/2 mice were induced aortitis and died at an incidence of 100% within several weeks. Histological findings included stenosis in the left ventricular outflow tract (LVOT) and severe inflammatory changes of the aortic valve with fibrinoid necrosis. Cardiomegaly was observed and heart weight increased 1.62 fold (P < 0.01). Echocardiography revealed a severe reduction in contractility and dilatation of the cavity in the left ventricle (LV): LV fractional shortening (LVFS) decreased from 71% to 38% (P < 0.01), and the LV end-diastolic diameter (LVDd) increased from 2.21 mm to 3.26 mm (P < 0.01). The titer of BNP mRNA increased in the CAWS-treated group. Severe inflammatory changes resulting from CAWS brought about lethal LV dysfunction by aortic valve deformation with LVOT stenosis. This system is proposed as an easy and useful experimental model of heart failure because CAWS arteritis can be induced by CAWS injection alone.

Vasculitis: molecular imaging by targeting the inflammatory enzyme myeloperoxidase

PURPOSE

To determine if a molecular imaging approach targeting the highly oxidative enzyme myeloperoxidase (MPO) can help noninvasively identify and confirm sites of vascular wall inflammation in a murine model of vasculitis.

MATERIALS AND METHODS

Animal experiments were approved by the institutional animal care committee. Twenty-six mice were studied, including eight MPO-deficient and six sham-operated mice as controls. Vasculitis was induced with intraperitoneal injection of Candida albicans water-soluble fraction (CAWS). Aortic root magnetic resonance imaging was performed after intravenous injection of the activatable MPO sensor (bis-5-hydroxytryptamide-diethylenetriaminepentatacetate gadolinium) (n = 23), referred to as MPO-Gd, or gadopentetate dimeglumine (n = 10). Seven mice were randomly assigned to receive either MPO-Gd or gadopentetate dimeglumine first. Aortic root specimens were collected for biochemical and histopathologic analyses to validate imaging findings. Statistical significance was calculated for contrast-to-noise ratios (CNRs) by using the paired t test.

RESULTS

In the aortic root, the mean MPO-Gd CNRs after agent injection (CNR = 28.1) were more than 2.5-fold higher than those of sham-operated mice imaged with MPO-Gd and vasculitis mice imaged with gadopentetate dimeglumine (CNR = 10.6) (P < .05). MPO-Gd MR imaging helped identify areas of vasculitis that were not seen at unenhanced and contrast material-enhanced imaging with gadopentetate dimeglumine. Histopathologic and biochemical analyses for MPO and myeloid cells confirmed imaging findings. In MPO-deficient mice, injection of CAWS did not result in a vasculitis phenotype, implying a key role of the imaging target in disease cause.

CONCLUSION

Molecular imaging targeting MPO can be a useful biomarker to noninvasively detect and confirm inflammation in vasculitis by using a murine model of Kawasaki disease.

Vasculitis and anaphylactoid shock in mice induced by the polysaccharide fraction secreted into culture supernatants by the fungus Candida metapsilosis

The biological effects of Candida metapsilosis water-soluble fraction (CMWS), prepared using a completely synthesized medium, were examined to determine whether CMWS induces vasculitis similar to that seen in Kawasaki disease, and anaphylactoid shock, in mice. It was found that intraperitoneal injection of CMWS induces coronary arteritis and i.v. injection induces acute anaphylactoid shock in mice, similar to Candida albicans water-soluble fraction (CAWS)-induced arteritis and anaphylactoid shock. The mannan structure of the polysaccharide fraction was then analyzed by performing antiserum reactivity tests and nuclear magnetic resonance spectroscopy. The mannan structure was investigated because the present authors have recently found that the mannan moiety within the polysaccharide fraction might be responsible for these pathogenic activities. The structural analysis showed that the mannan structure within CMWS expresses α-mannan residues, but not β-mannan. In addition, the mannan structure of CMWS is quite similar to that of CAWS. The present findings indicate that the polysaccharide fraction from C. metapsilosis, which is mainly composed of mannan, contributes to coronary arteritis and acute shock, and that the mannan structure could be responsible for this pathogenicity.

Administration of human immunoglobulin suppresses development of murine systemic vasculitis induced with Candida albicans water-soluble fraction: an animal model of Kawasaki disease

We investigated the inhibitory effect of human immunoglobulin (h-Ig) on the development of coronary arteritis in a murine model of vasculitis induced with a Candida albicans water-soluble fraction (CAWS). CAWS was intraperitoneally injected to C57BL/6 mice for 5 days. Then h-Ig was administered according to various schedules. The animals were sacrificed in week 5, and the status of vasculitis in the coronary arteries and the aortic root was investigated histologically. The groups in which h-Ig was administered for 5 days from day 3 and from day 5 of the experiment showed a significant reduction in the incidence of panvasculitis. In addition, the scope and severity of the inflammation of the aortic root and the coronary arteries were reduced in both groups. In the group administered h-Ig for 5 days from day 1 and the group administered a high dose of h-Ig once on day 1 or day 3, no suppression of development of vasculitis was observed. The h-Ig acted by suppressing the generation and progression of vasculitis in this CAWS-induced murine vasculitis model.

[Coronary arteritis induced by CAWS (Candida albicans water-soluble fraction) in various strains of mice]

The intraperitoneal administration of CAWS (water-soluble extracellular polysaccharide fraction obtained from the culture supernatant of Candida albicans NBRC 1385) to mice induces coronaritis similar to Kawasaki disease. We analyzed differences in the occurrence of coronary arteritis among mouse strains, inbred strains, a closed colony, hybrids and mutants. CAWS vasculitis was induced in almost all of the inbred and closed colony strains tested, except for CBA / J mice; it was induced also in hybrids, CDF1 and BDF1. In mutant strains of various immunological defects, such as C57BL / 6J Ham Slc-bg , Balb / c nu / nu , C.B.17 / Icr-scid / scid , WBB6F1-W / W (v) mice, all induced CAWS vasculitis but a relatively weak phenotype. It has already been postulated that CAWS vasculitis is regulated by various genes, those related to acute as well as chronic inflammation. This might well reflect the clinical situation in human disease.

Involvement of Platelet Activating Factor, Histamine and Serotonin in Acute Lethal Shock Induced by Candida albicans Water-Soluble Extracellular Polysaccharide Fraction (CAWS) in Mice

CAWS (Candida albicans water-soluble extracellular polysaccharide fraction) is a water-soluble extracellular mannoprotein-beta-glucan complex obtained from the culture supernatant following the culture of pathogenic Candida albicans in a completely synthetic medium. CAWS administered intraperitoneally induces vasculitis in mice, however, administered intravenously, it causes lethal shock. The acute lethal reaction to CAWS occurs within 1 h of intravenous administration, with the mice demonstrating anaphylactic shock-like symptoms including convulsion, diarrhea, and collapse. In this study, we analyzed the factors involved in this lethal effect. We examined physiologically active substances believed to be involved in anaphylactic shock, and found that the lethal effect of CAWS could be inhibited by blocking histamine, serotonin, and platelet activating factor (PAF) simultaneously, but by blocking only one. This finding strongly suggests that the acute lethal reaction to CAWS is a result of the simultaneous production of several physiologically active substances.

[Role of myeloperoxidase in the host defense against fungal infection]

Neutrophils are believed to be the first line of defense against invading microorganisms, but in vivo roles of reactive oxygens produced by neutrophils are not well known. Myeloperoxidase (MPO) catalyzes reaction of hydrogen peroxide with chloride ion to produce hypochlorous acid that is used for microbial killing by phagocytic cells. To define the in vivo role of MPO, we generated mice having no peroxidase activity in their neutrophils or monocytes. MPO-deficient (MPO-KO) mice showed severely reduced cytotoxicity to Candida albicans, Aspergillus fumigatus, Cryptococcus neoformans, and other microorganisms, demonstrating that an MPO-dependent oxidative system is important for host defense against fungi. However, the significance of MPO compared to the NADPH-oxidase is still unclear because individuals with MPO deficiency are usually healthy in contrast to patients with chronic granulomatous disease (CGD) who present clinical symptoms early in life. To better understand the contributions of MPO and NADPH-oxidase to antifungal defense mechanisms, we compared the susceptibility of MPO-KO mice and CGD mice to infections by C. albicans. Interestingly, at the highest dose, the mortality of MPO-KO mice was comparable to CGD mice, but was the same as normal mice at the lowest dose. These results suggest that MPO and NADPH-oxidase are equally important for early host defense against a large inocula of Candida. Our present results suggest that MPO-deficient individuals could exhibit similar problems as CGD patients if exposed to a large number of microorganisms.

Beta-mannosyl linkages negatively regulate anaphylaxis and vasculitis in mice, induced by CAWS, fungal PAMPS composed of mannoprotein-beta-glucan complex secreted by Candida albicans

Candida albicans water soluble fraction (CAWS) is a water-soluble extracellular mannoprotein-beta-glucan complex obtained from the culture supernatant of Candida albicans, which grows in a chemically defined medium. CAWS induced toxic reactions, such as acute anaphylactoid reaction, by intravenous administration and coronary arteritis by intraperitoneal administration. To clarify the structure responsible for these toxic reactions, C. albicans was cultured in pH- and temperature-controlled conditions and prepared with CAWS with or without the beta-1,2-linked mannosyl segment (BM). The structure of CAWS was assessed by immunochemical and spectroscopic methodologies, and we found that CAWS prepared under the natural culture conditions contained only small amounts of BM and CAWS prepared at neutral conditions at 27 degrees C contained a significantly higher percentage of BM. Both the acute lethal toxicity and coronary arteritis induction was significantly more severe in the absence of BM. Activation of a complement pathway, the lectin pathway, by CAWS was significantly stronger in the absence of BM. These facts strongly suggest that BM linkages in CAWS negatively modulate acute and chronic toxicity of CAWS, and may be strongly related to the lectin pathway of the complement activation.

[Anti-neutrophil cytoplasmic antibody MPO-ANCA related with disease activity of vasculitis]

Myeloperoxidase (MPO)-specific anti-neutrophil cytoplasmic antibodies (MPO-ANCA) are involved in the development of vasculitis microscopic polyangiitis, a systemic vasculitis etc. We have showed a correlation of MPO-ANCA epitopes in vasculitis concerning contribution of N and C terminus of MPO to severity of the diseases. On the other hand, a role of activated neutrophils in inflammatory nephritis renal lesions using SCG/Kj mice. In the phase of nephritis with a low grade of proteinuria, the spontaneous release of MPO from peripheral neutrophils increased, indicating that neutrophils are activated and contribute to the development of active crescentic lesions in SCG/Kj mice. In addition, we have investigated that mice having CADS/CAWS-induced vasculitis also are good model animals for the analysis of the production of MPO-ANCA. Furthermore, we have clarified that MPO is a major antigen for MPO-ANCA production using MPO knock mice.