Study Reveals How Insulin Fibrils from Infusion Pumps Trigger Immune Responses
A new study found that insulin-derived fibrils (IDFs) forming inside insulin infusion pumps activate macrophage inflammatory pathways, with phenolic preservatives significantly enhancing cytotoxicity and reactive oxygen species production. Researchers compared fibrils formed with and without common phenolic preservatives using bone marrow-derived macrophages, finding distinct immune activation mechanisms in each case. The findings suggest that reducing or removing insulin fibrils in continuous subcutaneous insulin infusion therapy could improve device longevity and biocompatibility for diabetes patients.
Researchers publishing on bioRxiv investigated how insulin-derived fibrils (IDFs) — protein aggregates that can form in insulin infusion pumps — affect immune cells, specifically bone marrow-derived macrophages (BMDMs). The study compared fibrils formed in the presence of phenolic preservatives, such as m-cresol (IDF+), to those formed without them (IDF-), finding that both types had similar physical aggregation states but triggered markedly different immune responses. IDF+ fibrils induced greater cytotoxicity and reactive oxygen species (ROS) production, while IDF- fibrils produced minimal ROS yet still elevated MIP-1 chemokine levels, indicating that inflammatory activation can occur independently of ROS. The study also found that IDF- upregulated the antioxidant transcription factor NRF2, while m-cresol alone downregulated STAT6, a signaling protein involved in anti-inflammatory responses. These divergent signaling profiles suggest that both the fibrils themselves and the preservatives they incorporate contribute to immune activation through separate molecular mechanisms. The authors conclude that strategies aimed at minimizing fibril formation or mitigating preservative effects in insulin delivery devices could reduce inflammation and extend device biocompatibility in people with diabetes.
What's missing
The study was conducted in vitro using mouse bone marrow-derived macrophages, and it is unclear whether these findings translate to human immune responses in vivo. The clinical prevalence and magnitude of IDF-related immune reactions in actual insulin pump users is not addressed, nor is the threshold fibril concentration required to produce these effects in a real-world infusion setting. As a preprint, the work has not yet undergone formal peer review.
What different sources said
- bioRxivCenter
Immunomodulatory Effects of Insulin-Derived Fibrils from Infusion Pumps: Role of Phenolic Preservatives in Macrophage Activation
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