Targeting inflammatory kidney disease locally using liposomal prednisolone

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C.M.A. van Alem, T. Bezhaeva, M. Boonstra, R.A. Lalai, A. Koudijs, J.M. Metselaar, M.E.J. Reinders, C. van Kooten, J.I. Rotmans

Chair(s): Drs. K.C.A. Geneugelijk & prof. dr. C. van Kooten

Thursday 9 march 2017

14:30 - 14:42h at Hendrik Marsmanzaal

Categories: Parallel - Basaal

Parallel session: Parallelsessie XV - Basaal - Moleculaire analyses en het adaptieve immuunsysteem in orgaantransplantatie

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Background:
Treatment with systemic high-dose corticosteroids (GCs) often leads to severe side effects. Liposomal encapsulation could facilitate local delivery of GCs in inflamed organs as circulating liposomes can hold their payload until they extravasate at sites of inflammation where they encounter phagocytic cells, resulting in local GC bioactivity instead of systemic exposure. This study focusses on the effect of liposomal prednisolone (LP) on macrophages, and the targeted delivery of liposomes to the kidney in a renal ischemia reperfusion injury (IRI) model in the rat.

Methods:
Male Lewis rats (9 per group) were subjected to 45 minutes clamping of the left renal blood vessels and were injected intravenously with a) fluorescent liposomes or b) 10 mg/kg LP, 10mg/kg prednisolone (P), an equal volume of empty liposomes (EL), or saline (S). At 96 hours, the kidneys were imaged using a near infra-red fluorescence camera and removed for histological analysis and RT-PCR. In vitro, LPS-activated human macrophages were incubated with 10 µg/mL LP, 10 µg/mL P, E, or S, and IL-6 production was measured using an ELISA.

Results:
In vivo imaging revealed that fluorescent liposomes accumulated in the injured kidneys when compared to the contralateral kidneys (MFI 10.6±3.1 vs 7.3±2.5, P<0.05). While treatment with LP and P did not affect influx of CD68(+) macrophages upon IRI, treatment with LP led to more anti-inflammatory CD163(+) macrophages compared to P-, EL- and S-treatment (2.8±1.5 vs 0.9±1.9%, 0.3±0.1%, 0.6±0.6%, p<0.05). In addition, MCP-1 mRNA was reduced from 8.7±2.4% to 3.5±2.0, and 4.8±2.9 (p<0.05) after S vs LP and P treatment. In vitro, both P or LP incubation of macrophages revealed a 73% decreased IL-6 production compared to cells incubated with S (0,18±0,06 and 0,27±0,11 vs 1,0±0,0, p>0,05).

Conclusions:
LP treatment of the inflamed kidney leads to increased local uptake and a shift of the infiltrate towards M2 macrophages, which is accompanied by a reduced production of pro-inflammatory cytokines. Liposomal encapsulation is therefore a promising strategy for targeted delivery of GCs to the inflamed kidney.