Thermoresponsive Nanogel–cytokine Conjugates for Spatiotemporally Controlled Modulation of Neuroinflammation

Introduction: Neuroinflammation following acute brain injury contributes to secondary neuronal damage. Although anti-inflammatory cytokines like interleukin-10 (IL-10) show therapeutic promise, their systemic use is limited by rapid clearance, poor blood–brain barrier (BBB) penetration and off-target immunosuppression. To address these challenges, we developed a thermoresponsive nanogel system for targeted, hyperthermia-triggered cytokine delivery. Methods: Poly (N-isopropylacrylamide-acrylic acid) nanogels with a lower critical solution temperature of 38.5°C were synthesised via microfluidic precipitation polymerisation. IL-10 was covalently conjugated to the nanogel matrix, and Angiopep-2 peptides were grafted to enable receptor-mediated BBB transcytosis. Nanogels were characterised by dynamic light scattering, differential scanning calorimetry and MALDI-TOF mass spectrometry. In vitro assays assessed thermoresponsive swelling, IL-10 release and BBB penetration using a bEnd. 3 Transwell model. In vivo efficacy was evaluated in a mouse model of traumatic brain injury using near-infrared imaging and cytokine profiling. Results: Nanogels exhibited reversible size transitions from 120 nm at 37°C to 65 nm at 39°C, with temperature-dependent IL-10 release reaching 75% at 39°C versus 20% at 37°C over 24 h. Angiopep-2 functionalisation enhanced in vitro transcytosis 3.5-fold and increased in vivo brain accumulation to 4.7% injected dose per gram in injured cortex versus 1.2% in controls ( P < 0.01, ANOVA, n = 5). In lipopolysaccharide-stimulated BV2 cells, nanogel–IL-10 reduced tumour necrosis factor-alpha secretion by 78%. In vivo , treatment decreased microglial activation by 60% and increased Arg-1-positive cells 3.2-fold. Conclusion: This thermoresponsive, actively targeted nanogel platform enables precise, inflammation-triggered cytokine delivery with enhanced BBB penetration. It significantly attenuates neuroinflammation in preclinical models and offers a modular framework for treating central nervous system disorders characterised by localised inflammatory activity.