MKK3 depletion attenuates intestinal injury after traumatic hemorrhagic shock by restoring mitochondrial function.

BACKGROUND: Traumatic hemorrhagic shock (THS) is a complex pathophysiological process resulting in multiple organ failure. Intestinal barrier dysfunction is one of the mechanisms implicated in multiple organ failure. The present study aimed to explore the regulatory role of mitogen-activated protein kinase kinase 3 (MKK3) in THS-induced intestinal injury and to elucidate its potential mechanism. METHODS: Rats were subjected to trauma and hemorrhage to establish a THS animal model. MKK3-targeted lentiviral vectors were injected via the tail vein 72 h before modeling. Twelve hours post-modeling, the mean arterial pressure (MAP) and heart rate (HR) were monitored, and histological injury to the intestine was assessed via H&E staining and transmission electron microscopy. Mitochondrial function and mitochondrial reactive oxygen species (ROS) were evaluated. IEC-6 cells were exposed to hypoxia to mimic intestinal injury following THS in vitro. RESULTS: MKK3 deficiency alleviated intestinal injury and restored mitochondrial function in intestinal tissues from THS-induced rats and hypoxia-treated IEC-6 cells. In addition, MKK3 deficiency promoted Sirt1/PGC-1α-mediated mitochondrial biogenesis and restricted Pink1/Parkin-mediated mitophagy in the injured intestine and IEC-6 cells. Furthermore, the protective effect of MKK3 knockdown against hypoxia-induced mitochondrial damage was strengthened upon simultaneous LC3B/Pink1/Parkin knockdown or weakened upon simultaneous Sirt1 knockdown. CONCLUSION: MKK3 deficiency protected against intestinal injury induced by THS by promoting mitochondrial biogenesis and restricting excessive mitophagy.

Mesenchymal stem cells overexpressing PBX1 alleviates haemorrhagic shock-induced kidney damage by inhibiting NF-κB activation.

Mesenchymal stem cells (MSCs) have favourable outcomes in the treatment of kidney diseases. Pre-B-cell leukaemia transcription factor 1 (PBX1) has been reported to be a regulator of self-renewal of stem cells. Whether PBX1 is beneficial to MSCs in the treatment of haemorrhagic shock (HS)-induced kidney damage is unknown. We overexpressed PBX1 in rat bone marrow-derived mesenchymal stem cells (rBMSCs) and human bone marrow-derived mesenchymal stem cells (hBMSCs) to treat rats with HS and hypoxia-treated human proximal tubule epithelial cells (HK-2), respectively. The results indicated that PBX1 enhanced the homing capacity of rBMSCs to kidney tissues and that treatment with rBMSCs overexpressing PBX1 improved the indicators of kidney function, alleviated structural damage to kidney tissues. Furthermore, administration with rBMSCs overexpressing PBX1 inhibited HS-induced NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation and the release of proinflammatory cytokines, and further attenuated apoptosis. We then determined whether NF-κB, an important factor in NLRP3 activation and the regulation of inflammation, participates in HS-induced kidney damage, and we found that rBMSCs overexpressing PBX1 inhibited NF-κB activation by decreasing the p-IκBα/IκBα and p-p65/p65 ratios and inhibiting the nuclear translocation and decreasing the DNA-binding capacity of NF-κB. hBMSCs overexpressing PBX1 also exhibited protective effects on HK-2 cells exposed to hypoxia, as shown by the increase in cell viability, the mitigation of apoptosis, the decrease in inflammation, and the inhibition of NF-κB and NLRP3 inflammasome activation. Our study demonstrates that MSCs overexpressing PBX1 ameliorates HS-induced kidney damage by inhibiting NF-κB pathway-mediated NLRP3 inflammasome activation and the inflammatory response.