Anti-Inflammatory Effect of Anti-TNF-α SiRNA Cationic Phosphorus Dendrimer Nanocomplexes Administered Intranasally in a Murine Acute Lung Injury Model

Abstract

Inflammation is an essential component of many lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), or acute lung injury. Our purpose was to design efficient carriers for lung delivery of small interfering RNA (siRNA) targeting tumor necrosis factor (TNF-α) in an acute lung injury model. To achieve this goal, two different types of phosphorus-based dendrimers with either pyrrolidinium or morpholinium as terminal protonated amino groups were selected for their better biocompatibility compared to other dendrimers. Dendriplexes containing pyrrolidinium surface groups demonstrated a stronger siRNA complexation, a higher cellular uptake, and enhanced in vitro silencing efficiency of TNF-α in the lipopolysaccharide (LPS)-activated mouse macrophage cell line RAW264.7, compared to morpholinium-containing dendriplexes. The better performance of the pyrrolidium dendriplexes was attributed to their higher pK value leading to a stronger siRNA complexation and improved protection against enzymatic degradation resulting in a higher cellular uptake. The superior silencing effect of the pyrrolidinium dendriplexes, compared to noncomplexed siRNA, was confirmed in vivo in an LPS-induced murine model of short-term acute lung injury upon lung delivery via nasal administration. These data suggest that phosphorus dendriplexes have a strong potential in lung delivery of siRNA for treating inflammatory lung diseases.

Elucidating the role of surface chemistry on cationic phosphorus dendrimer–siRNA complexation

“…Dendrimer customization consists of tuning either the structure flexibility 31-34 or surface properties 35 .…”

“…It is worth mentioning that DP and DM differ only for their terminal groups. Both dendrimers were efficient to complex an anti TNF-α siRNA but complexes were shown more stable in vitro for pyrrolidinium, leading to more effective anti-inflammatory effect by inhibition of TNF-α both in vitro and in vivo 35 . These findings show that a small chemical modification may result in a significant change of the biological activity of the compounds.…”

“…Dendrimers are unique tree-like branched polymers with biomolecules-like properties, low polydispersity and high degree of versatility; outstanding features for nanomedicine [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] . Dendrimer customization consists of tuning either the structure flexibility [31][32][33][34] or surface properties 35 . Polymer flexibility has been demonstrated to play a crucial role for complexation with siRNA 32, 36,37 .…”

“…In connection with siRNA delivery, cationic phosphorus dendrimers have been demonstrated to be good candidates for gene delivery carriers after in vivo experiments 35,39 . In particular, in a recent study 35 , two different cationic, phosphorus dendrimers of generation 3 were synthesized and functionalized with either cationic pyrrolidinium or morpholinium surface groups and called DP and DM, respectively. It is worth mentioning that DP and DM differ only for their terminal groups.…”

“…Here, following this strategy, we used single-molecule resolution techniques such as Isothermal Titration Calorimetry (ITC) [44][45][46][47] together with Molecular Dynamics simulations [48][49][50][51] , to shed light on the molecular reasons behind the DP and DM exhibited activity 35 . In more details, single-molecule level investigation of dendrimer-siRNA interactions was used to better understand how changes in dendrimer structure and biophysical properties affect the interaction with siRNA and lately emerges in a different biological activity, as recently shown 35 . Outcomes of the present research may also be used for further design of siRNA delivery agents characterized by the best compromise between complexation stability and release ability.…”