Modulating macrophage phenotypes via immune-switch magnetic nanoparticles


Almeida, Ana F. (3B's Research Group, I3Bs (University of Minho))


"Introduction: Inflammation is a physiological process in healing however, persistent inflammation signals hold deleterious consequences to the tissue and contributes to the inhibition of regeneration. Resolving inflammation remains an unmet challenge with great impact in the management of chronic inflammatory disorders and for the treatment of tissue injuries. Interleukin 4 (IL4) is a well-known key regulator of macrophage function by stimulating M2 phenotype (1), which is associated with the resolution of inflammation and structural tissue healing, and to dampen macrophage responsiveness to inflammation via IL4-pSTAT6 pathway. Despite IL4 promise towards tissue regeneration, hurdles in IL4 associated to in vivo instability and diminished bioactivity, demand for alternative vehicles to efficiently deliver IL4 and modulate macrophage functions, fostering resolution of persistent inflammatory cues with coordinated action over inflammatory cascades. Magnetic technologies offer promising tools that would precisely deliver biomolecules and control their action via IL4-pSTAT6 pathway (2), while providing contactless control, local retention and real time traceability using conventional imaging techniques. Thus, we propose to use superparamagnetic iron oxide nanoparticles (SPION) as magnetic field-responsive carriers for IL4 presentation, to remotely control immunoregulation of macrophages to favor the M2 phenotype via IL4-pSTAT6 pathway.

Methodology: Commercially available superparamagnetic iron oxide nanoparticles (SPION) were conjugated to a M2 macrophage promoter (IL4) via carbodiimide chemistry (SPION-IL4). The system was characterized according to dimension, shape, and charge as well as for IL4 binding efficiency. THP1-derived macrophages were used to investigate viability and the expression of immune-modulatory molecules in the presence of SPION-IL4. Two time-points (1h or 24h) were investigated, and two SPION concentrations (30 or 100 µg/mL) studied to insight on the impact of IL4 to drive M2 macrophages. These outcomes were compared against exogenous IL4 (Exo IL4)-stimulated THP1 (control group). A magnetic field was provided by a magnefect device (nanoTherics Ltd, UK) (350 mT/ well) for magnetic guidance and IL4 presentation to macrophages.

Results: Magnetically guided SPION-IL4 were shown to contribute for immune strategies participating in M2 polarization via IL4-pSTAT6 pathway. After 24h, our results have shown the levels of pSTAT6 trended higher in THP1 cells treated with SPION-IL4 comparing to Exo IL4. Furthermore, SPION-IL4-treated macrophages showed increased expression of M2 genes: IL10 and ARG1, and of M2 related proteins: CCL2 and IL1Ra, in comparison to Exo IL4, highlighting the effectiveness and impact of SPION-IL4 driving M2 signals.

Conclusions: This work reports the contribution of SPION-IL4 in IL4 mediated actions, taking advantage of SPION-IL4 magnetic responsiveness to deliver IL4 to macrophages and to promote M2 switch with the participation of STAT6. These findings show that SPION-IL4 influence pro-regenerative features in macrophages, and that SPIONs hold potential to be explored as a magnetically controlled system for targeted delivery of immunomodulatory triggers or combined with more sophisticated systems aiming at strategies for improved tissue healing.

Acknowledgements: NORTE-01-0145-FEDER-000021; ERC CoG MagTendon No.772817; EC Twinning project Achilles No.810850; FCT Doctoral Grant SFRD/BD/144816/2019.

References: 1. Stein, M et al. J Exp Med, 1992, 176(1), 287-92; 2. Gonçalves, A.I., et al, Biomed Mater, 2018."


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