Luminol-conjugated cyclodextrin biological nanoparticles for the treatment of severe burn-induced intestinal barrier disruption.

Background: The breakdown of intestinal barrier integrity occurs after severe burn injury and is responsible for the subsequent reactions of inflammation and oxidative stress. A new protective strategy for the intestinal barrier is urgently needed due to the limitations of the traditional methods. Recently, the application of nanoparticles has become one of the promising therapies for many inflammation-related diseases or oxidative damage. Herein, we developed a new anti-inflammatory and antioxidant nanoparticle named luminol-conjugated cyclodextrin (LCD) and aimed to evaluate its protective effects in severe burn-induced intestinal injury. Methods: First, LCD nanoparticles, engineered with covalent conjugation between luminol and ß-cyclodextrin (ß-CD), were synthesized and examined. Then a mouse burn model was successfully established before the mouse body weight, intestinal histopathological manifestation, permeability, tight junction (TJ) expression and pro-inflammatory cytokines were determined in different groups. The proliferation, apoptosis, migration and reactive oxygen species (ROS) of intestinal epithelial cells (IECs) were assessed. Intraepithelial lymphocytes (IELs) were isolated and cultured for analysis by flow cytometry. Results: LCD nanoparticle treatment significantly relieved the symptoms of burn-induced intestinal injury in the mouse model, including body weight loss and intestinal permeability abnormalities. Moreover, LCD nanoparticles remarkably recovered the mechanical barrier of the intestine after severe burn, renewed TJ structures, promoted IEC proliferation and migration, and inhibited IEC apoptosis. Mechanistically, LCD nanoparticles dramatically alleviated pro-inflammation factors (tumor necrosis factor-α, IL-17A) and ROS accumulation, which could be highly involved in intestinal barrier disruption. Furthermore, an increase in IL-17A and the proportion of IL-17A+Vγ4+ γδ T subtype cells was also observed in vitro in LPS-treated Vγ4+ γδ T cells, but the use of LCD nanoparticles suppressed this increase. Conclusions: Taken together, these findings demonstrate that LCD nanoparticles have the protective ability to ameliorate intestinal barrier disruption and provide a therapeutic intervention for burn-induced intestinal injury.

Vagus Nerve Stimulation Prevents Endothelial Necroptosis to Alleviate Blood-Spinal Cord Barrier Disruption After Spinal Cord Injury.

Vagus nerve stimulation (VNS) is a promising neuromodulation technique, which has been demonstrated to promote functional recovery after spinal cord injury (SCI) in our previous study. But the underlying mechanism remains to be explored. Using a compressed SCI model, our present study first demonstrated that activated microglia produce abundant tumor necrosis factor-α (TNF-α) to induce endothelial necroptosis via receptor-interacting protein kinase 1 (RIP1)/RIP3/mixed lineage kinase domain-like protein (MLKL) pathway, thus destroying the blood-spinal cord barrier (BSCB) after SCI. While both TNF-α specifical antibody (infliximab) and necroptosis inhibitor (necrostatin-1) alleviate BSCB disruption. Then our study found that VNS significantly inhibits microglia-derived TNF-α production and reduces expression of p-RIP3 and p-MLKL in endothelial cells. As expected, further results indicated that VNS mitigates the BSCB disruption, thus reducing inflammatory cells infiltration and neural damage. Finally, both electrophysiological evaluation and locomotor test demonstrated that VNS promotes motor function recovery after SCI. In conclusion, our data demonstrated VNS restricts microglia-derived TNF-α to prevent RIP1/RIP3/MLKL mediated endothelial necroptosis, thus alleviating the decisive pathophysiological BSCB disruption to reduce neuroinflammation and neural damage, which ultimately promotes motor function recovery after SCI. Therefore, these results further elaborate that VNS might be a promising therapeutic strategy for SCI. Vagus nerve stimulation prevents microglia-derived TNF-α induced endothelial necroptosis to alleviate blood-spinal cord barrier disruption after spinal cord injury.

Transcranial direct current stimulation regulates phenotypic transformation of microglia to relieve neuropathic pain induced by spinal cord injury.

Objective: Neuropathic pain is a common complication after spinal cord injury (SCI). Transcranial direct current stimulation (tDCS) has been confirmed to be effective in relieving neuropathic pain in patients with SCI. The aim of this study is to investigate the effect of tDCS on neuropathic pain induced by SCI and its underlying mechanism. Materials and methods: The SCI model was induced by a clip-compression injury and tDCS stimulation was performed for two courses (5 days/each). The motor function was evaluated by Basso-Beattie-Bresnahan (BBB) score, and the thermal withdrawal threshold was evaluated by the thermal radiation method. The effects of tDCS on the cerebral cortex, thalamus, midbrain, and medulla were detected by the enzyme-linked immunosorbent assay (ELISA) and immunofluorescence. Results: The results showed that SCI reduced the thermal withdrawal threshold and increased the concentration of inflammatory cytokines in the cortex, thalamus, midbrain, and medulla, including the tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6). In addition, the activation of microglia and the proportion of M1 phenotypic polarization increased significantly in the ventral posterolateral (VPL), ventral tegmental (VTA), and periaqueductal gray (PAG) regions after SCI. After tDCS treatment, the thermal withdrawal threshold and motor function of SCI rats were significantly improved compared to the vehicle group. Meanwhile, tDCS effectively reduced the concentration of pro-inflammatory cytokines in the cortex, thalamus, midbrain, and medulla and increased the concentration of anti-inflammatory cytokines interleukin-10 (IL-10) in the thalamus. In addition, tDCS reduced the proportion of the M1 phenotype of microglia in VPL, VTA, and PAG regions and increase the proportion of the M2 phenotype. Conclusion: The results suggest that tDCS can effectively relieve SCI-induced neuropathic pain. Its mechanism may be related to regulating the inflammatory and anti-inflammatory cytokines in corresponding brain regions via promoting the phenotypic transformation of microglia.

Iron overload in the motor cortex induces neuronal ferroptosis following spinal cord injury.

Motor neuron death is supposed to result in primary motor cortex atrophy after spinal cord injury (SCI), which is relevant to poorer motor recovery for patients with SCI. However, the exact mechanisms of motor neuron death remain elusive. Here, we demonstrated that iron deposition in the motor cortex was significantly increased in both SCI patients and rats, which triggered the accumulation of lipid reactive oxygen species (ROS) and resulted in motor neuronal ferroptosis ultimately. While iron chelator, ROS inhibitor and ferroptosis inhibitor reduced iron overload-induced motor neuron death and promoted motor functional recovery. Further, we found that activated microglia in the motor cortex following SCI secreted abundant nitric oxide (NO), which regulated cellular iron homeostasis-related proteins to induce iron overload in motor neurons. Thus, we conclude that microglial activation induced iron overload in the motor cortex after SCI triggered motor neuronal ferroptosis and impeded motor functional recovery. These findings might provide novel therapeutic strategies for SCI.

Iron-induced neuronal damage in a rat model of post-traumatic stress disorder.

Previous studies have shown that iron redistribution and deposition in the brain occurs in some neurodegenerative diseases, and oxidative damage due to abnormal iron level is a primary cause of neuronal death. In the present study, we used the single prolonged stress (SPS) model to mimic post-traumatic stress disorder (PTSD), and examined whether iron was involved in the progression of PTSD. The anxiety-like behaviors of the SPS group were assessed by the elevated plus maze (EPM) and open field tests, and iron levels were measured by inductively coupled plasma optical emission spectrometer (ICP-OES). Expression of glucocorticoid receptors and transferrin receptor 1 (TfR1) and ferritin (Fn) was detected by Western blot and immunohistochemistry in selected brain areas; TfR1 and Fn mRNA expression were detected by quantitative-polymerase chain reaction (Q-PCR). Ultrastructures of the hippocampus were observed under a transmission electron microscope. Our results showed that SPS exposure induced anxiety-like symptoms and increased the level of serum cortisol and the concentration of iron in key brain areas such as the hippocampus, prefrontal cortex, and striatum. The stress induced region-specific changes in both protein and mRNA levels of TfR1 and Fn. Moreover, swelling mitochondria and cell apoptosis were observed in neurons in brain regions with iron accumulation. We concluded that SPS stress increased iron in some cognition-related brain regions and subsequently cause neuronal injury, indicating that the iron may function in the pathology of PTSD.

ABCG2 regulates the pattern of self-renewing divisions in cisplatin-resistant non-small cell lung cancer cell lines.

Overexpression of ABCG2 is considered a major mechanism of cancer drug resistance. Recent studies have shown that ABCG2 can regulate the switch between symmetric and asymmetric cell division in adult stem cells; however, the relationship between ABCG2 and cell division in drug-resistant cancer cells remains to be determined. In the present study, we demonstrated that ABCG2 is involved in the cell division of drug-resistant cancer cells. We first established drug-resistant H460 and A549 cell lines by repeated exposure to cisplatin and found that the expression of ABCG2 in these cell lines was significantly increased. As evidenced by PKH-26 staining, these drug-resistant cell lines favored symmetric division, which differed from the asymmetric division of the parental cells. Furthermore, we established stable ABCG2­overexpressing and stable shRNA-ABCG2­knockdown cell lines to evaluate the potential role of ABCG2 in cancer cell division. The results showed that overexpression of ABCG2 in A549 parental cells significantly increased the proportion of symmetric division, whereas knockdown of ABCG2 in drug-resistant A549 cells significantly increased the proportion of asymmetric division. Taken together, our findings suggest that ABCG2 is involved in the modulation of cancer drug resistance by regulating the pattern of cell division. The present study provides novel insight into the role of ABCG2 in cancer treatment resistance.

Nicotinamide pretreatment protects cardiomyocytes against hypoxia-induced cell death by improving mitochondrial stress.

BACKGROUND/AIMS: Nicotinamide plays a protective role in hypoxia-induced cardiomyocyte dysfunction. However, the underlying molecular mechanisms remain poorly understood. The purpose of this study was to investigate these and the effect of nicotinamide pretreatment on hypoxic cardiomyocytes. METHODS: Cultured rat cardiomyocytes were pretreated with nicotinamide, subjected to hypoxia for 6 h, and then cell necrosis and apoptosis were examined. The effects of nicotinamide pretreatment on hypoxia-induced reactive oxygen species (ROS) formation, antioxidant enzyme expression, nicotinamide adenine dinucleotide (NAD(+)) and nicotinamide adenine dinucleotide phosphate (NADP(+)) levels, adenosine triphosphate (ATP) production and mitochondrial membrane potential were tested to elucidate the underlying mechanisms. RESULTS: Based on the findings that nicotinamide treatment decreased protein expression of receptor-interacting protein (RIP; a marker for cell necrosis) and cleaved caspase-3 (CC3; a marker for cell apoptosis) in normoxic cardiomyocytes, we found that it dramatically reduced hypoxia-induced necrosis and apoptosis in cardiomyocytes. The underlying mechanisms of these effects are associated with the fact that it increased protein expression of superoxide dismutase and catalase, increased intracellular levels of NAD(+) and ATP concentration, decreased mitochondrial ROS generation and prevented the loss of mitochondrial membrane potential. CONCLUSION: All of these results indicate that nicotinamide pretreatment protects cardiomyocytes by improving mitochondrial stress. Our study provides a new clue for the utilization of nicotinamide in therapies for ischemic heart disease.