Noninvasive Contrast-Enhanced Ultrasound Molecular Imaging Detects Myocardial Inflammatory Response in Autoimmune Myocarditis

Abstract

Background-Cardiac tests for diagnosing myocarditis lack sensitivity or specificity. We hypothesized that contrastenhanced ultrasound molecular imaging could detect myocardial inflammation and the recruitment of specific cellular subsets of the inflammatory response in murine myocarditis. Methods and Results-Microbubbles (MB) bearing antibodies targeting lymphocyte CD4 (MB CD4 ), endothelial P-selectin (MB PSel ), or isotype control antibody (MB Iso ) and MB with a negative electric charge for targeting of leukocytes (MB Lc ) were prepared. Attachment of MB CD4 was validated in vitro using murine spleen CD4+ T cells. Twenty-eight mice were studied after the induction of autoimmune myocarditis by immunization with α-myosin-peptide; 20 mice served as controls. Contrast-enhanced ultrasound molecular imaging of the heart was performed. Left ventricular function was assessed by conventional and deformation echocardiography, and myocarditis severity graded on histology. Animals were grouped into no myocarditis, moderate myocarditis, and severe myocarditis. In vitro, attachment of MB CD4 to CD4+ T cells was significantly greater than of MB Iso . Of the left ventricular ejection fraction or strain and strain rate readouts, only longitudinal strain was significantly different from control animals in severe myocarditis. In contrast, contrast-enhanced ultrasound molecular imaging showed increased signals for all targeted MB versus MB Iso both in moderate and severe myocarditis, and MB CD4 signal correlated with CD4+ T-lymphocyte infiltration in the myocardium. Conclusions-Contrast-enhanced ultrasound molecular imaging can detect endothelial inflammation and leukocyte infiltration in myocarditis in the absence of a detectable decline in left ventricular performance by functional imaging.In particular, imaging of CD4+ T cells involved in autoimmune responses could be helpful in diagnosing myocarditis.(Circ Cardiovasc Imaging. 2016;9:e004720.

Ultrasound/Optical Dual‐Modality Imaging for Evaluation of Vulnerable Atherosclerotic Plaques with Osteopontin Targeted Nanoparticles

“…Therefore, in this study, the UCAs were selected as the probe carrier. Owing to the relatively lower ultrasound reflection, PFOB nanoparticles have limitations in detecting plaques . So, optical imaging is utilized as a complement for ultrasound to improve its sensitivity in detecting plaques.…”

“…It is well recognized that nanoprobes mainly consists of the biomarkers and the materials, and the former determines the specificity and sensitivity of the probe while the latter determines the imaging performance and biocompatibility of the probe. For example, Steinl et al used lymphocyte CD4 targeted UCAs to detect leukocyte infiltration and endothelial inflammation in myocarditis under the absence of a detectable decline in left ventricular performance . Kaufmann et al used vascular cell adhesion molecule‐1 targeted UCAs for quantifying vascular inflammatory changes that occur in the progression of atherosclerosis plaques .…”

“…Commercial UCAs comprise encapsulated gas microbubbles, which oscillate under the ultrasound wave to enhance the echogenicity. Despite the high sensitive detection offered by the obvious nonlinear response of microbubbles, these type of UCAs still have limitations owing to their short half‐lives, high background signal, and instability in vivo . PFOB nanoparticles, which are resistant to ultrasound pressure changes and mechanical stress, owns a relatively stable echogenic response without increasing the background signal, exhibiting low acoustic attenuation.…”

Seeing the Invisible—Ultrasound Molecular Imaging

“…This strategy can be useful for detecting specific leukocyte populations of interest that are in the process of intravascular recruitment. Examples of this strategy include the targeting of specific reparative monocyte subpopulations using CX3 CR-1 (Ryu et al 2013), of granulocytes through targeting complement receptors (Lindner 2004;Mott et al 2016) and of certain T-lymphocyte populations by targeting CD3 or CD4 (Steinl et al 2016;Liu et al 2018).…”

Detection of Myocarditis With Molecular Echo Imaging

“…Steinl et al created a murine model of varying severities of autoimmune myocarditis and, at 21 days, intravenously injected microbubbles that were targeted to either CD4 on lymphocytes or endothelial P-selectin. 5 Subsequent molecular imaging of retained targeted microbubble contrast was effective at detecting the presence of myocarditis. Traditional echocardiographic measurements like ejection fraction and left ventricular mass were not effective in distinguishing normal myocardium from active myocarditis.…”