NBR1-p62-Nrf2 mediates the anti-pulmonary fibrosis effects of protodioscin.

BACKGROUND: Idiopathic pulmonary fibrosis is a persistent disease of the lung interstitium for which there is no efficacious pharmacological therapy. Protodioscin, a steroidal saponin, possesses diverse pharmacological properties; however, its function in pulmonary fibrosis is yet to be established. Hence, in this investigation, it was attempted to figure out the anti-pulmonary fibrosis influences of protodioscin and its pharmacological properties related to oxidative stress. METHODS: A mouse lung fibrosis model was generated using tracheal injections of bleomycin, followed by intraperitoneal injection of different concentrations of protodioscin, and the levels of oxidative stress and fibrosis were detected in the lungs. Multiple fibroblasts were treated with TGF-ß to induce their transition to myofibroblasts. It was attempted to quantify myofibroblast markers' expression levels and reactive oxygen species levels as well as Nrf2 activation after co-incubation of TGF-ß with fibroblasts and different concentrations of protodioscin. The influence of protodioscin on the expression and phosphorylation of p62, which is associated with Nrf2 activation, were detected, and p62 related genes were predicted by STRING database. The effects of Nrf2 inhibitor or silencing of the Nrf2, p62 and NBR1 genes, respectively, on the activation of Nrf2 by protodioscin were examined. The associations between p62, NBR1, and Keap1 in the activation of Nrf2 by protodioscin was demonstrated using a co-IP assay. Nrf2 inhibitor were used when protodioscin was treated in mice with pulmonary fibrosis and lung tissue fibrosis and oxidative stress levels were detected. RESULTS: In vivo, protodioscin decreased the levels of fibrosis markers and oxidative stress markers and activated Nrf2 in mice with pulmonary fibrosis, and these effects were inhibited by Nrf2 inhibitor. In vitro, protodioscin decreased the levels of myofibroblast markers and oxidative stress markers during myofibroblast transition and promoted Nrf2 downstream gene expression, with reversal of these effects after Nrf2, p62 and NBR1 genes were silenced or Nrf2 inhibitors were used, respectively. Protodioscin promoted the binding of NBR1 to p62 and Keap1, thereby reducing Keap1-Nrf2 binding. CONCLUSION: The NBR1-p62-Nrf2 axis is targeted by protodioscin to reduce oxidative stress and inhibit pulmonary fibrosis.

CPT1A as a potential therapeutic target for lipopolysaccharide-induced acute lung injury in mice.

Acute lung injury (ALI) remains a high mortality rate with dramatic lung inflammation and alveolar epithelial cell death. Although fatty acid ß-oxidation (FAO) impairment has been implicated in the pathogenesis of ALI, whether Carnitine palmitoyltransferase 1A (CPT1A), the rate-limiting enzyme for FAO, plays roles in lipopolysaccharide (LPS)-induced ALI remains unclear. Accordingly, we focused on exploring the effect of CPT1A in the context of ALI and the underlying mechanisms. We found that overexpression of CPT1A (AAV-CPT1A) effectively alleviated lung injury by reduction of lung wet-to-dry ratio, inflammatory cell infiltration, and protein levels in the BALF of ALI mice. Meanwhile, AAV-CPT1A significantly lessened histopathological changes and several cytokines' secretions. In contrast, blocking CPT1A with etomoxir augmented inflammatory responses and lung injury in ALI mice. Furthermore, we found that overexpression of CPT1A with lentivirus reduced the apoptosis rates of alveolar epithelial cells and the expression of apoptosis-related proteins induced by LPS in MLE12 cells, while etomoxir increased the apoptosis of MLE12 cells. Overexpression of CPT1A prevented the drop in bioenergetics, palmitate oxidation, and ATP levels. In conclusion, the results rendered CPT1A worthy of further development into a pharmaceutical drug for the treatment of ALI.

Kindlin-2 protects pancreatic ß cells through inhibiting NLRP3 inflammasome activation in diabetic mice.

Diabetes mellitus has been a major public health problem worldwide, characterized by insulin resistance and dysfunction of ß-cells. A previous study showed that Kindlin-2 loss in ß-cells dramatically reduces insulin secretion and decreases ß-cell mass, resulting in severe diabetes-like phenotypes. It suggests that Kindlin-2 in ß-cells play an important role in regulating glucose homeostasis. However, the effect of Kindlin-2 on the function of ß-cells under chronic hyperglycemia in diabetes has not been explored. Here we report that Kindlin-2 overexpression ameliorates diabetes and improves insulin secretion in mice induced by streptozocin. In contrast, Kindlin-2 insufficiency exacerbates diabetes and promotes ß-cells dysfunction and inflammation in ß-cells induced by a high-fat diet (HFD). In vitro, Kindlin-2 overexpression prevented high-glucose (HG)-induced dysfunction in ß-cells. Kindlin-2 overexpression also decreased the expression of pro-inflammatory cytokines and NLRP3 inflammasome expression in ß-cells exposed to HG. Furthermore, the loss of Kindlin-2 aggravates the expression of inflammatory cytokines and NLRP3 induced by HG in ß-cells. Collectively, we demonstrate that Kindlin-2 protects against diabetes by inhibiting NLRP3 inflammasome activation.