Pulsed Ultrasound of the Spleen Prolongs Survival of Rats With Severe Intra-abdominal Sepsis

Abstract

BackgroundThe spleen is an important contributor to the uncontrolled, excessive release of proinflammatory signals during sepsis that leads to the development of tissue injury and diffuse end-organ dysfunction. Therapeutic pulsed ultrasound (pUS) has been shown to inhibit splenic leukocyte release and reduce cytokine production in other inflammatory disease processes. We hypothesized that pUS treatment inhibits spleen-derived inflammatory responses and increases survival duration in rats with severe intra-abdominal sepsis leading to septic shock.Materials and methodsRats with intra-abdominal sepsis, induced by cecal ligation and incision, underwent abdominal washout, intra-peritoneal administration of cefazolin, and then either no further treatment (control), splenectomy, or pUS of the spleen. Animals were observed for the primary endpoint of survival duration.ResultsSurvival curves were significantly different for all groups (P < 0.01). Median survival increased from 9.5 h in control rats to 19.8 h in pUS rats and 35.0 h in splenectomy rats (P < 0.01). At 4 h after cecal ligation and incision, the pUS group had decreased splenic contraction and leukocyte count (P = 0.03) compared with control, indicating reduced exodus of splenic leukocytes. In addition, elevation in plasma TNF-α and MCP-1 was significantly attenuated in the pUS group (P < 0.05 versus control). Splenic β2 adrenergic receptor levels and phosphorylated Akt were significantly more elevated in the pUS group (P < 0.01 versus control).ConclusionspUS significantly prolonged the survival duration of rats with severe intra-abdominal sepsis. This treatment may be an effective, noninvasive therapy that dampens detrimental immune responses during septic shock by activating β2 adrenergic receptor–Akt phosphorylation in the cholinergic anti-inflammatory pathway.

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