Anti-Inflammatory Strategy for M2 Microglial Polarization Using Retinoic Acid-Loaded Nanoparticles

Figure 2

RA-NP induced an M2 microglial phenotype under inflammatory challenge. (a) None of the cell treatments (RA-NP, blank NP or free RA) affected NO levels in the absence of a stimulus. (b) RA-NP (10 μg/mL) and free RA (0.4 and 10 μM) inhibited NO production in the presence of 100 ng/mL LPS (24 hours) (; compared to untreated cells; ^#, ^## compared to LPS). (c) RA-NP (10 μg/mL) decreased LPS-induced iNOS expression while free RA had no effect (; compared to untreated cells, ^# compared to LPS). (d) RA-NP (10 μg/mL) increased LPS-inhibited Arg-1 expression. Free RA (0.4 μM) had no effect (; compared to untreated cells, ^# compared to LPS). (e) RA-NP (10 μg/mL) increased IL-4 expression while free RA had no effect (; compared to untreated cells, ^## compared to LPS). (f) Representative confocal images depicting expression of iNOS, Arg-1, and IL-4 after cell treatments (in red; top, middle, and bottom panels, resp.). Nuclear staining in blue. Scale bar 10 μm.

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