IL-1 receptor antagonist, anakinra, prevents myocardial dysfunction in a mouse model of Kawasaki disease vasculitis and myocarditis

Abstract

Kawasaki disease (KD) vasculitis is an acute febrile illness of childhood characterized by systemic vasculitis of unknown origin, and is the most common cause of acquired heart disease among children in the United States. While histological evidence of myocarditis can be found in all patients with acute KD, only a minority of patients are clinically symptomatic and a subset demonstrate echocardiographic evidence of impaired myocardial function, as well as increased left ventricular mass, presumed to be due to myocardial edema and inflammation. Up to a third of KD patients fail to respond to first-line therapy with intravenous immunoglobulin (IVIG), and the use of interleukin (IL)-1 receptor antagonist (IL-1Ra, anakinra) is currently being investigated as an alternative therapeutic approach to treat IVIG-resistant patients. In this study, we sought to investigate the effect of IL-1Ra on myocardial dysfunction and its relation to myocarditis development during KD vasculitis. We used the Lactobacillus casei cell-wall extract (LCWE)-induced murine model of KD vasculitis and investigated the effect of IL-1Ra pretreatment on myocardial dysfunction during KD vasculitis by performing histological, magnetic resonance imaging (MRI) and echocardiographic evaluations. IL-1Ra pretreatment significantly reduced KD-induced myocardial inflammation and N-terminal pro B-type natriuretic peptide (NT-proBNP) release. Both MRI and echocardiographic studies on LCWE-injected KD mice demonstrated that IL-1Ra pretreatment results in an improved ejection fraction and a normalized left ventricular function. These findings further support the potential beneficial effects of IL-1Ra therapy in preventing the cardiovascular complications in acute KD patients, including the myocarditis and myocardial dysfunction associated with acute KD.

Keywords: IL-1; IL-1Ra; Kawasaki disease; MRI; NT-proBNP; anakinra; echocardiogram; myocardial edema; myocarditis; vasculitis.

Figure 1

Interleukin (IL)‐1Ra treatment prevents coronary and myocardial inflammation in the Lactobacillus casei cell‐wall extract (LCWE) murine model of Kawasaki disease (KD) vasculitis. (a) Schema of the study experimental design. Mice received either LCWE or LCWE with IL‐1Ra, which was given daily for 6 consecutive days starting 1 day before LCWE injection. Heart tissues were harvested at the indicated time‐points and heart inflammation was evaluated by hematoxylin and eosin (H&E) staining. (b) Representative H&E staining of heart sections from LCWE‐injected mice with and without IL‐1Ra treatment at 7, 14 and 35 days post‐LCWE injection. Scale bars indicate 500 µm. (c,d) Vascular (c) and myocardial (d) inflammation score of untreated and IL‐1Ra pretreated LCWE‐injected mice. (e) Serum N‐terminal‐prohormone B‐type natriuretic peptide (NT‐ProBNP) levels of untreated and IL‐1Ra pretreated LCWE‐injected mice 2 weeks post‐LCWE injection. Data are presented as mean ± standard error of the mean (s.e.m.); n = 5–9 mice per group. *P < 0·05, **P < 0·01 and ***P < 0·001 by one and two‐way analysis of variance (ANOVA) with Tukey's post‐test analysis.

Figure 2

Interleukin (IL)‐1Ra treatment prevents myocardial dysfunction and ventricular enlargement. (a) Schema of the magnetic resonance imaging (MRI) study experimental design. Mice received either Lactobacillus casei cell‐wall extract (LCWE) or LCWE with IL‐1Ra, which was given daily for 6 consecutive days starting 1 day before LCWE injection. MRI analysis was performed at the indicated different time‐points. (b–d) Ventricular ejection fraction (b), end‐point diastolic (c) and ‐systolic (d) volume measured at days 7, 14 and 35 post‐LCWE injection by MRI studies. (e) Heart rate (beats per minute; bpm) measurement in phosphate‐buffered saline (PBS) control mice, LCWE‐injected mice and LCWE‐injected mice pretreated with IL‐1Ra at 7 days post‐LCWE‐injection. Data are presented as mean ± standard error of the mean (s.e.m.); n = 5–9 mice per group. *P < 0·05, **P < 0·01 and ***P < 0·001 by one and two‐way analysis of variance (ANOVA) with Tukey's post‐test analysis.

Figure 3

Echocardiogram analysis reveals that interleukin (IL)‐1Ra anakinra treatment prevents Lactobacillus casei cell‐wall extract (LCWE)‐induced myocardial dysfunction and ventricular enlargement. (a) Schema of the echocardiogram experimental design. Mice received either phosphate‐buffered saline (PBS), LCWE alone or LCWE with IL‐1Ra which was given daily for 5 consecutive days starting 1 day before LCWE injection. Echocardiogram analysis was performed at days 7, 14, 21, 28, 35 and 42 post‐LCWE injection. (b–e) Ejection fraction (b), fractional shortening (c), left ventricular mass/body weight (d), end‐diastolic volume (e) and end‐systolic volume (f) measured in PBS control mice, LCWE‐injected mice and LCWE‐injected mice pretreated with IL‐1Ra. (g) M‐mode measurements (red bars) of interventricular septum (IVS), left ventricular internal dimensions (LVID) and left ventricular posterior wall (LVPW) in PBS control mice, LCWE injected mice and LCWE‐injected mice pretreated with IL‐1Ra. (h,i) IVS (h) and LVPW (i) quantification during diastole in PBS control mice, LCWE‐injected mice and LCWE‐injected mice pretreated with IL‐1Ra. (j) Ratio of the IVS to LVPW in PBS control mice, LCWE‐injected mice and LCWE‐injected mice pretreated with IL‐1Ra. Data represent mean ± standard error of the mean (s.e.m.), where n = 8 mice per group. Statistics are comparing LCWE‐injected versus LCWE‐injected IL‐1Ra pretreated mice. *P < 0·05, **P < 0·01 and ***P < 0·001 by two‐way analysis of variance (ANOVA) with Tukey's post‐test analysis.