Targeting NRF2 to promote epithelial repair

Curcumin-mediated NRF2 induction limits inflammatory damage in, preclinical models of cystic fibrosis

BACKGROUND

Overactive neutrophilic inflammation causes damage to the airways and death in people with cystic fibrosis (CF), a genetic disorder resulting from mutations in the CFTR gene. Reducing the impact of inflammation is therefore a major concern in CF. Evidence indicates that dysfunctional NRF2 signaling in CF individuals may impair their ability to regulate their oxidative and inflammatory responses, although the role of NRF2 in neutrophil-dominated inflammation and tissue damage associated with CF has not been determined. Therefore, we examined whether curcumin, an activator of NRF2, might provide a beneficial effect in the context of CF.

METHODS

Combining Cftr-depleted zebrafish as an innovative biomedical model with CF patient-derived airway organoids (AOs), we aimed to understand how NRF2 dysfunction leads to abnormal inflammatory status and tissue remodeling and determine the effects of curcumin in reducing inflammation and tissue damage in CF.

RESULTS

We demonstrate that NFR2 is instrumental in regulating neutrophilic inflammation and repair processes in vivo, thereby preventing inflammatory damage. Importantly, curcumin treatment restores NRF2 activity in both CF zebrafish and AOs. Curcumin reduces neutrophilic inflammation in CF context, by rebalancing the production of epithelial ROS and pro-inflammatory cytokines. Furthermore, curcumin improves tissue repair by reducing CF-associated fibrosis. Our findings demonstrate that curcumin prevents CF-mediated inflammation via activating the NRF2 pathway.

CONCLUSIONS

This work highlights the protective role of NRF2 in limiting inflammation and injury and show that therapeutic strategies to normalize NRF2 activity, using curcumin or others NRF2 activators, might simultaneously reduce airway inflammation and damage in CF.

Platelet-Released Growth Factors (PRGFs) Activate NRF2-ARE and Modulate Inflammatory Response in an NRF2-Dependent Manner in Primary Human Keratinocytes

BACKGROUND

Platelet-released-growth factors (PRGF) and platelet-rich plasma (PRP) are blood-derived products used in regenerative treatments and in overall aesthetic rejuvenation. Keratinocytes possess distinctive characteristics responsible for protection against environmental stressors and oxidant clearance. One such mechanism is the transcription factor NRF2, which plays a critical role in regulating cytoprotective genes, inflammation, and oxidative stress response. Data on the activation of the NRF2-ARE and NF-κB axes by PRGF are very limited.

AIM

This study aims to investigate whether PRGF activates NRF2 and, if so, is responsible for the described anti-inflammatory effect of PRGF/PRP in an in vitro primary human keratinocyte model.

METHODS

NRF2 activation is analyzed by NQO1 and HO-1 western blotting, gene expression analysis, and by an ARE-promoter study using luciferase-based reporter gene assays in patient-derived keratinocytes. Besides direct determination of the PRGF-NRF2 interaction, we investigated the NF-κB response by treating cells with PRGF and the inflammatory stimuli TNF-α. Inflammatory parameters were analyzed using ELISAs for IL-1β, IL-4, Il-10, TNF-α and IL-6 in the supernatant, NF-κB luciferase reporter gene assays as well a-NF-κB western blotting. NRF2 involvement was tested by treating the cell-culture model with the NRF2-inhibitor ML-385.

RESULTS

We were able to show that ARE activity was significantly upregulated in PRGF-treated keratinocytes, leading subsequently to increased NQO1 and HO-1 protein expression. Inflammatory IL-secretion showed an association with NRF2 availability.

CONCLUSIONS

In summary, PRGFs activate NRF2 target proteins and downregulate NF-κB-associated inflammation in an NRF2-dependent manner. Therefore, we further suggest PRGF as an anti-inflammatory treatment after medical aesthetic procedures.

Screening and Antioxidant Activities Evaluation of Peptides From Abalone (Haliotis discus hannai Ino)

Marine organisms are rich in antioxidant peptides; however, extracting these peptides is time-consuming, labor-intensive, and costly, with sequence losses leading to uncertain results. This study aimed to identify abalone-derived antioxidant peptides with strong Keap1 binding ability and validate their antioxidative activities using a cellular oxidative damage model. We constructed an abalone-derived peptide library comprising 363 peptides using virtual enzymatic hydrolysis techniques. Of the 98 human Keap1 protein structures available in the protein data bank database, 2FLU was selected as the receptor. Using the CDOCKER module in Discovery Studio software, molecular docking was performed with the peptide library as ligands and 2FLU as the receptor, targeting the binding site at coordinates x: 5.000222, y: 7.103889 and z: 5.058000. Ten abalone-derived peptides with the strongest inhibition against Keap1-Nrf2 interaction were identified. A 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AAPH)-induced oxidative damage model in human umbilical vein endothelial cells (HUVECs) was used to verify the molecular docking results and identified DEDEDEDK as the most active antioxidant peptide. DEDEDEDK interferes with Keap1-Nrf2 binding, significantly reducing reactive oxygen species levels in damaged cells, increasing superoxide dismutase and catalase activities, and elevated glutathione content, indicating its potential to mitigate AAPH-induced oxidative damage in HUVECs.

Nrf-2 as a novel target in radiation induced lung injury

Radiation-induced lung injury (RILI) is a common and fatal complication of chest radiotherapy. The underlying mechanisms include radiation-induced oxidative stress caused by damage to the deoxyribonucleic acid (DNA) and production of reactive oxygen species (ROS), resulting in apoptosis of lung and endothelial cells and recruitment of inflammatory cells and myofibroblasts expressing NADPH oxidase to the site of injury, which in turn contribute to oxidative stress and cytokine production. Nuclear factor erythroid 2-related factor 2 (Nrf-2) is a vital transcription factor that regulates oxidative stress and inhibits inflammation. Studies have shown that Nrf-2 protects against radiation-induced lung inflammation and fibrosis. This review discusses the protective role of Nrf-2 in RILI and its possible mechanisms.

Targeting Signalling Pathways in Chronic Wound Healing

Chronic wounds fail to achieve complete closure and are an economic burden to healthcare systems due to the limited treatment options and constant medical attention. Chronic wounds are characterised by dysregulated signalling pathways. Research has focused on naturally derived compounds, stem-cell-based therapy, small molecule drugs, oligonucleotide delivery nanoparticles, exosomes and peptide-based platforms. The phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT), Wingless-related integration (Wnt)/β-catenin, transforming growth factor-β (TGF-β), nuclear factor erythroid 2-related factor 2 (Nrf2), Notch and hypoxia-inducible factor 1 (HIF-1) signalling pathways have critical roles in wound healing by modulating the inflammatory, proliferative and remodelling phases. Moreover, several regulators of the signalling pathways were demonstrated to be potential treatment targets. In this review, the current research on targeting signalling pathways under chronic wound conditions will be discussed together with implications for future studies.

Mechanism of Nrf2 in the treatment of ulcerative colitis via regulating macrophage polarization

Ulcerative colitis (UC) is an inflammatory bowel disease induced by multiple factors, which causes abnormal activation of intestinal immune cells and excessive release of antibodies and inflammatory factors, repeatedly damaging the intestinal mucosa. Macrophages, as innate intestinal immune cells, often maintain the balance of M1/M2 macrophages polarization to normalize the regression inflammation, and the imbalance of their polarization will cause repeated damage of intestinal mucosa and persistent inflammation, which is a main cause of UC. Nuclear factor E2-related factor 2 (Nrf2), as an important regulator of antioxidant and anti-inflammatory, is often used as a target for the treatment of autoimmune diseases.Nrf2 alleviates intestinal high oxidative stress and inflammatory factors by balancing macrophage polarization, which may be of great significance for the prevention and treatment of UC. Summarizing the mechanism of macrophage polarization imbalance on the course of UC and the possible regulatory mechanism of Nrf2 may provide basis for the development of UC targeted therapeutic drugs.