Inhibition of Human Neutrophil Elastase by α₁-Antitrypsin Functionalized Colloidal Microcarriers

Abstract

Layer-by-layer (LbL)-coated microcarriers offer a good opportunity as transport systems for active agents into specific cells and tissues. The assembling of oppositely charged polyelectrolytes enables a modular construction of the carriers and therefore an optimized integration and application of drug molecules. Here, we report the multilayer incorporation and transport of R 1 -antitrypsin (AT) by colloidal microcarriers. AT is an anti-inflammatory agent and shows inhibitory effects toward its proinflammatory antagonist, human neutrophil elastase (HNE). The highly proteolytic enzyme HNE is released by polymorphonuclear leukocytes (PMNs) during inflammatory processes and can cause host tissue destruction and pain. The high potential of this study is based on a simultaneous intraand extracellular application of AT-functionalized LbL carriers. Carrier application in PMNs results in significant HNE inhibition within 21 h. Microcarriers phagocytosed by PMNs were time dependently decomposed inside phagolysosomes, which enables the step-by-step release of AT. Here, AT inactivates HNE before being released, which avoids a further HNE concentration increase in the extracellular space and, subsequently, reduces the risk of further tissue destruction. Additionally, AT surface-functionalized microcarriers allow the inhibition of already released HNE in the extracellular space. Finally, this study demonstrates the successful application of LbL carriers for a concurrent extra-and intracellular HNE inhibition aiming the rebalancing of protease and antiprotease concentrations and the subsequent termination of chronic inflammations.

The Application of LbL-Microcarriers for the Treatment of Chronic Inflammation: Monitoring the Impact of LbL-Microcarriers on Cell Viability

“…This is possible since even large objects in micrometer dimension will be incorporated by those professional phagocytes; (ii) A microcarrier‐mediated (further) induction of PMN's necrosis and even apoptosis has to be strongly avoided to prevent secondary proinflammatory signaling of macrophages. To fulfil those demands, our group recently presented a very efficient approach in the parallel, that is extracellular as well as intracellular, inhibition of the human neutrophil elastase (HNE) by LbL‐microcarrier delivered α 1 ‐antitrypsin (AT) . HNE is a highly proteolytic enzyme, which is stored in azurophilic granules of PMNs, released in the course of inflammation and subsequently responsible for the destruction of the affected tissue .…”

Colloidal micro- and nano-particles as templates for polyelectrolyte multilayer capsules

“…The release of biomolecules, such as small drug molecules from particles [56], is governed by an interplay of drug desorption and carrier dissolution [57]. This process usually is very slow, especially in the absence of a payload-specific solvent, but could be increased when the carrier size is reduced.…”

Pharmacological aspects of release from microcapsules — from polymeric multilayers to lipid membranes

“…Layer-by-layer assembly offers very attractive means of particle modification and controllability of release [121,122]. An interesting approach for obtaining particles follows from obtaining polymer-filled template [123] or for surface initiated polymerization on silica [124].…”