Blocking RAGE improves wound healing in diabetic pigs

Simultaneous regulation of AGE/RAGE signaling and MMP-9 expression by an immunomodulating hydrogel accelerates healing in diabetic wounds

PURPOSE

In chronic hyperglycemia, the advanced glycation end product (AGE) interacts with its receptor (RAGE) and contributes to impaired wound healing by inducing oxidative stress, generating dysfunctional macrophages, and prolonging the inflammatory response. Additionally, uncontrolled levels of proteases, including metallomatrix protease-9 (MMP-9), in the diabetic wound bed degrade the extracellular matrix (ECM) and biological cues that augment healing. A multifunctional antimicrobial hydrogel (Immuno-gel) containing RAGE and MMP-9 inhibitors can regulate the wound microenvironment and promote scar-free healing.

RESULTS

Immuno-gel was characterized and the wound healing efficacy was determined in vitro cell culture and in vivo diabetic Wistar rat wound model using ELISA, Western blot, and Immunofluorescence staining. The Immuno-gel exhibited a highly porous morphology with excellent in vitro cytocompatibility. AGE-stimulated macrophages treated with the Immuno-gel released higher levels of pro-healing cytokines in vitro. In the hydrogel-wound interface of diabetic Wistar rats, Immuno-gel treatment significantly reduced MMP-9 and NF-κB expression and enhanced pro-healing (M2) macrophage population and pro-healing cytokines.

CONCLUSION

Altogether, this study suggests that Immuno-gel simultaneously attenuates macrophage dysfunction through the inhibition of AGE/RAGE signaling and reduces MMP-9 overexpression, both of which favor scar-free healing. The combinatorial treatment with RAGE and MMP-9 inhibitors via Immuno-gel simultaneously modulates the diabetic wound microenvironment, making it a promising novel treatment to accelerate diabetic wound healing.

Modulatory Effects of 830 nm on Diabetic Wounded Fibroblast Cells: An In Vitro Study on Inflammatory Cytokines

Background:After skin damage, a complicated set of processes occur for epidermal and dermal wound healing. This process is hindered under diabetic conditions, resulting in nonhealing diabetic ulcers. In diabetes there is an increase in inflammation and proinflammatory cytokines. Modulating cells using photobiomodulation (PBM) may have an effect on inflammation and cell viability, which are crucial for the healing of wounds. Objective: This study explored the impact of PBM in the near-infrared spectrum (830 nm; 5 J/cm2) on inflammation in diabetic wound healing. Materials and Methods: Five cell models, namely normal, wounded, diabetic, diabetic wounded, and wounded with d-galactose were used. Cell morphology and migration rate were assessed, while cellular response measures included viability (Trypan blue and adenosine triphosphate), apoptosis (annexin-V/PI), proinflammatory cytokines interleukin-6, tumor necrosis factor-alpha (TNF-α), and cyclooxygenase-2, nuclear translocation of nuclear factor kappa B (NF-κB), and gene expression of advanced glycation end product receptor (AGER). Results: PBM resulted in increased levels of TNF-α, supported by activation of NF-κB. PBM stimulated translocation of NF-κB and upregulation of AGER. Conclusions: PBM modulates diabetic wound healing in vitro at 830 nm through stimulated NF-κB signaling activated by TNF-α.