Efficient delivery of small interfering RNA for inhibition of IL-12p40 expression <it>in vivo</it>

• Main Authors: Flynn Marion A, Casey David G, Todryk Stephen M, Mahon Bernard P
• Format: Article
• Language: English
• Published: BMC 2004-10-01
• Series: Journal of Inflammation
• Online Access: http://www.journal-inflammation.com/content/1/1/4

<p>Abstract</p> <p>Background</p> <p>RNA interference is an evolutionary conserved immune response mechanism that can be used as a tool to provide novel insights into gene function and structure. The ability to efficiently deliver small interfering RNA to modulate gene expression <it>in vivo </it>may provide new therapeutic approaches to currently intractable diseases.</p> <p>Methods</p> <p><it>In vitro</it>, siRNA targeting IL-12p40 was delivered to the murine macrophage cell line (J774A.1) encapsulated in a liposome with an IL-12 inducing agent (LPS/IFN-γ) over a number of time points. Controls included a variety of non-target specific siRNA reagents. Supernatants were analyzed for cytokine production while the cells were removed for mRNA profiling.</p> <p><it>In vivo</it>, siRNA-targeting IL-12p40 was delivered to the murine peritoneal cavity in a therapeutic fashion, after endotoxin (LPS) challenge. Cells from the peritoneal cavity were removed by lavage and analyzed by flow cytometry. Levels of IL-12 present in lavage and in serum were also examined by ELISA.</p> <p>Results</p> <p>In this report, we show that IL-12p40 siRNA can specifically silence macrophage expression of IL-12p40 mRNA and IL-12p70 protein <it>in vitro</it>. We extend this finding to demonstrate that delivery of liposome encapsulated siRNA targeting IL-12p40 to the murine peritoneal cavity can modulate an inflammatory stimulus <it>in vivo</it>. Furthermore, specific siRNA can be used therapeutically after endotoxin challenge to reduce both the local and systemic inflammatory response. Thus, the delivery of siRNA can be used to elicit specific non-permanent inhibition of endogenous protein expression.</p> <p>Conclusion</p> <p><it>In vitro </it>silencing of IL-12p40 using siRNA at selected doses leads to specific knockdown of IL-12p70 protein production without inducing type I interferons. Furthermore, siRNA targeting murine IL-12p40 can be used therapeutically to counter an inflammatory response <it>in vivo</it>.</p>