Background: Accumulating evidence now shows that a cardio-splenic axis plays critical role in post-ischemic reperfusion injury of the heart. Here, we tested a nonpharmacologic, noninvasive, ultrasound-based treatment of the spleen to reduce myocardial ischemia-reperfusion injury in mice.

Methods and Results: C57BL6 (B6) mice and IL-10 Knockout (KO) mice underwent 40 min of LAD occlusion followed by 60 min of reperfusion. Ultrasound of the spleen (US-treated, US-T) versus ultrasound of the liver (US-control, US-C) was performed 24 hours before LAD occlusion. The TTC & Blue staining results showed that risk regions of all groups were identical. US-treated mice had significantly smaller myocardial infarct size than the US-control mice (p<0.05). In B6 mice, splenectomy (SPLX) performed 30 min before ischemia reduced infarct size. Acute adoptive transfer of splenocytes (SPAT) from US-control B6 mice performed 25 min before ischemia significantly exacerbated the infarct size in SPLX mice. However, SPAT of the US-treated splenocytes abrogated this exacerbation of the infarct size (Figure). Western blot analysis showed that ultrasound significantly increased the splenic phosphorylation Akt levels at 24 hours after US treatment. Furthermore, splenic ultrasound failed to protect the myocardial ischemia-reperfusion injury in IL-10 KO mice.

Conclusions: These results suggested that an ultrasound-based treatment could have therapeutic potential for attenuation of post-ischemic myocardial reperfusion injury, possibly by stimulating a splenic anti-inflammatory effect via an Akt-IL-10 Pathway.