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Laminin interactions in a 3D reverse thermal gel scaffold promote islet survival under cytokine-mediated stress
El-Dirani, Christine Murthy, Meghana Shivananda Park, Daewon Farnsworth, Nikki
El-Dirani, Christine
Murthy, Meghana Shivananda
Park, Daewon
Farnsworth, Nikki
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2025-04
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Abstract
Type 1 diabetes (T1D) is characterized by autoimmune-mediated destruction of insulin-producing ? cells in pancreatic islets. Infiltrating immune cells secrete high levels of pro-inflammatory cytokines that disrupt islet function and lead to ?-cell death in early T1D. The peri-islet extracellular matrix (ECM) serves as a protective barrier and is crucial for islet survival. Specifically, laminin supports ?-cell survival via transmembrane integrins. In several cell types, laminin receptor activity is linked to protein kinase C ? (PKC?), a key regulator of apoptosis. Laminin is also known to engage the PI3K/Akt pro-survival pathway in ? cells. Thus, we hypothesize that loss of laminin interactions with the islet in T1D enhances cytokine-mediated ?-cell death via PKC? activation and dysregulation of the PI3K/Akt pro-survival pathway.
To investigate laminin’s protective role, we encapsulated C57Bl/6 mouse islets in a 3D reverse thermal gel (RTG) alone or functionalized with laminin (RTG-LAM) and treated them with a pro-inflammatory cytokine cocktail (10ng/mL TNF-?, 5ng/mL IL-1? and 10ng/mL IFN-?) for 24 hours. Islet interactions with laminin significantly protected against cytokine-induced death (p=0.027). Using a membrane-targeted FRET biosensor in MIN6 cells and a GFP-tagged PKC? fusion protein in intact islets, we found that laminin reduced PKC? activity at the cell membrane (p=0.039). To determine if laminin in the RTG activates a downstream pro-survival pathway in ?-cells, we will perform western blot analysis on components of the PI3K/Akt signaling pathway. Overall, our results suggest that laminin interactions protect islets from cytokine-induced apoptosis, which may be mediated by PKC? and downstream signaling pathways.
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