Ya-Lei Ning

Ski, a modulator of wound healing and scar formation in the rat skin and rabbit ear.

We recently demonstrated that Ski is a novel wound healing‐related factor that promotes fibroblast proliferation and inhibits collagen secretion. Here, we show that increasing local Ski expression by gene transfer not only significantly accelerated wound healing by relieving inflammation, accelerating re‐epithelialization and increasing formation of granulation tissue, but also reduced scar formation by decreasing collagen production in rat dermal wounds. Similarly, ski gene transfer accelerated wound healing, reduced the protuberant height and volume of scars and increased collagen maturity in a hypertrophic scar model in the rabbit ear. Conversely, reducing Ski expression in the wound by RNA interference resulted in significantly slower wound healing and increased scar area in rat dermal wounds. We demonstrated that these effects of Ski are associated with transforming growth factor‐β‐mediated signalling pathways through both Smad2/3‐dependent and Smad‐independent pathways. Together, our results define a dual role for Ski in promoting wound healing and alleviating scar formation, identifying a new target for therapeutic approaches to preventing scar hyperplasia and accelerating wound healing. Copyright

Adenosine A2A receptor deficiency alleviates blast-induced cognitive dysfunction

Traumatic brain injury (TBI), particularly explosive blast-induced TBI (bTBI), has become the most prevalent injury among military personnel. The disruption of cognitive function is one of the most serious consequences of bTBI because its long-lasting effects prevent survivors fulfilling their active duty and resuming normal civilian life. However, the mechanisms are poorly understood and there is no treatment available. This study investigated the effects of adenosine A2A receptor (A2AR) on bTBI-induced cognitive deficit, and explored the underlying mechanisms. After being subjected to moderate whole-body blast injury, mice lacking the A2AR (A2AR knockout (KO)) showed less severity and shorter duration of impaired spatial reference memory and working memory than wild-type mice did. In addition, bTBI-induced cortical and hippocampal lesions, as well as proinflammatory cytokine expression, glutamate release, edema, cell loss, and gliosis in both early and prolonged phases of the injury, were significantly attenuated in A2AR KO mice. The results suggest that early injury and chronic neuropathological damages are important mechanisms of bTBI-induced cognitive impairment, and that the impairment can be attenuated by preventing A2AR activation. These findings suggest that A2AR antagonism is a potential therapeutic strategy for mild-to-moderate bTBI and consequent cognitive impairment.

Plasma glutamate–modulated interaction of A2AR and mGluR5 on BMDCs aggravates traumatic brain injury–induced acute lung injury

Activation of adenosine A2A receptor aggravates lung damage in a neurogenic mouse model of acute lung injury (ALI) but protects against nonneurogenic ALI.

The -144C/A polymorphism in the promoter of HSP90beta is associated with multiple organ dysfunction scores.

Introduction Variations in genetic background are the leading cause of differential susceptibility to traumatic infection. Heat shock protein 90 (HSP90), a broadly distributed and conserved molecule, regulates inflammation under stressful and traumatic conditions. However, the relationships between HSP90 genetic polymorphisms, post-traumatic inflammatory responses and organ function remain unknown. Methods A total of 286 healthy volunteers and patients with severe trauma took part in a single nucleotide polymorphism (SNP)-based analysis of the HSP90beta gene and a clinical association analysis. HSP90beta and TNF-alpha levels were determined using quantitative PCR and western blot. The transcriptional activity of the HSP90beta promoter was assayed using the Dual-Luciferase Reporter Assay System. Results The minor allele frequencies for the SNP located at −144 bp relative to the HSP90beta transcriptional start site were 28.47% and 28.52% in the normal and trauma populations, respectively; no significant differences were found between these two distributions. However, the results showed that a promoter containing the -144A allele had a higher transcriptional activity than did a promoter containing the wild-type -144C allele. Furthermore, the -144A promoter induced high expression of HSP90beta and low expression of the inflammatory factor TNF-alpha in a lipopolysaccharide-induced inflammatory model. A clinical association analysis showed that the multiple organ dysfunction scores for -144AA genotype carriers were significantly lower than those of -144CC carriers following trauma. No significant correlations were found between the presence of the two alleles and the incidence of sepsis. Conclusions These results indicate that differences in expression caused by the -144 polymorphism in the HSP90beta promoter are associated with cellular inflammatory responses and the severity of organ injury. These findings will aid in risk assessment and early prevention of complications for patients with severe trauma.

The glucocorticoid dexamethasone inhibits U937 cell adhesion and neutrophil release via RhoA/ROCK1-dependent and independent pathways.

Aims: The aim of the present study was to investigate the role of the Ras homolog family member A (RhoA)/Rho-associated coiled-coil-containing protein kinase 1 (ROCK1) signaling pathway in the inhibition of inflammatory responses by the glucocorticoid dexamethasone (Dex). Methods: The inhibitory effects of Dex and Rho-kinase inhibitor fasudil (Fas) on phorbol ester-induced release of O2- and MPO from neutrophils and on U937 mononuclear cell adhesion were examined along with the expression and activity levels of RhoA and ROCK1. Results: High doses of Dex rapidly inhibited the release of O2- and myeloperoxidase (MPO) from neutrophils and the adhesion of U937 cells, while Fas was only found to inhibit U937 cell adhesion. Additionally, Dex suppressed ROCK1 activity. However, Dex had no effects on ROCK1 or RhoA expression levels or on RhoA activity. Neither the glucocorticoid receptor antagonist mifepristone (RU-486) nor the protein synthesis inhibitor cycloheximide (CHX) was able to suppress the effects of Dex (p>0.05). Conclusions: The present findings indicate that Dex suppressed neutrophil release through ROCK1-independent mechanisms and inhibited the adhesion of U937 mononuclear cells through ROCK1-dependent non-genomic mechanisms that did not involve RhoA.

Perivascular AQP4 dysregulation in the hippocampal CA1 area after traumatic brain injury is alleviated by adenosine A 2A receptor inactivation

Traumatic brain injury (TBI) can induce cognitive dysfunction due to the regional accumulation of hyperphosphorylated tau protein (p-tau). However, the factors that cause p-tau to concentrate in specific brain regions remain unclear. Here, we show that AQP4 polarization in the perivascular astrocytic end feet was impaired after TBI, which was most prominent in the ipsilateral brain tissue surrounding the directly impacted region and the contralateral hippocampal CA1 area and was accompanied by increased local p-tau, changes in dendritic spine density and morphology, and upregulation of the adenosine A2A receptor (A2AR). The critical role of the A2AR signaling in these pathological changes was confirmed by alleviation of the impairment of AQP4 polarity and accumulation of p-tau in the contralateral CA1 area in A2AR knockout mice. Given that p-tau can be released to the extracellular space and that the astroglial water transport via AQP4 is involved in tau clearance from the brain interstitium, our results suggest that regional disruption of AQP4 polarity following TBI may reduce the clearance of the toxic interstitial solutes such as p-tau and lead to changes in dendritic spine density and morphology. This may explain why TBI patients are more vulnerable to cognitive dysfunction.

Dramatic increases in blood glutamate concentrations are closely related to traumatic brain injury-induced acute lung injury

Traumatic brain injury-induced acute lung injury (TBI-ALI) is a serious complication after brain injury for which predictive factors are lacking. In this study, we found significantly elevated blood glutamate concentrations in patients with TBI or multiple peripheral trauma (MPT), and patients with more severe injuries showed higher blood glutamate concentrations and longer durations of elevated levels. Although the increase in amplitude was similar between the two groups, the duration was longer in the patients with TBI. There were no significant differences in blood glutamate concentrations in the patients with MPT with regard to ALI status, but the blood glutamate levels were significantly higher in the patients with TBI-ALI than in those without ALI. Moreover, compared to patients without ALI, patients with TBI showed a clearly enhanced inflammatory response that was closely correlated with the blood glutamate levels. The blood glutamate concentration was also found to be a risk factor (adjusted odds ratio, 2.229; 95% CI, 1.082–2.634) and was a better predictor of TBI-ALI than the Glasgow Coma Scale (GCS) score. These results indicated that dramatically increased blood glutamate concentrations were closely related to the occurrence of TBI-ALI and could be used as a predictive marker for “at-risk” patients.

Comparative evaluation of the wound-healing potency of recombinant bFGF and ski gene therapy in rats

Abstract We previously demonstrated that cellular Sloan-Kettering Institute (c-Ski) played a dual role, both promoting wound healing and alleviating scar formation. However, its mechanism and therapeutic effects are not clear, especially compared with widely used treatments, such as basic fibroblast growth factor (bFGF) administration. However, Ski treatment led to an even shorter healing time and a more significant reduction in scar area than bFGF treatment. The mechanism underlying this difference was related to a reduced inflammatory response, more rapid re-epithelialization, less collagen after healing and a greater reduction in the proportion of alpha-smooth muscle actin and SMemb-positive cells after Ski treatment. These results not only confirm that Ski plays a dual role in promoting healing and reducing scarring but also suggest that Ski yields better treatment effects than bFGF, indicating better potential therapeutic effects in wound repair.

Blood Glutamate Levels Are Closely Related to Acute Lung Injury and Prognosis after Stroke

Background Acute lung injury (ALI) is a serious complication of stroke that occurs with a high incidence. Our preclinical results indicated that ALI might be related to blood glutamate levels after brain injury. The purpose of this study was to assess dynamic changes in blood glutamate levels in patients with stroke and to determine the correlation between blood glutamate levels, ALI, and long-term prognosis after stroke. Methods Venous blood samples were collected from controls and patients with stroke at admission and on the third and seventh day after the onset of stroke. Patients were followed for 3 months. The correlations among blood glutamate levels, severities of stroke and ALI, and long-term outcomes were analyzed, and the predictive values of blood glutamate levels and severity scores for ALI were assessed. Results In this study, a total of 384 patients with stroke were enrolled, with a median age of 59 years. Patients showed significantly increased blood glutamate levels within 7 days of stroke onset (p < 0.05), and patients with more severe injuries showed higher blood glutamate levels. Moreover, blood glutamate levels were closely related to the occurrence (adjusted odds ratio, 3.022, p = 0.003) and severity (p < 0.001) of ALI and the long-term prognosis after stroke (p < 0.05), and they were a more accurate predictor of ALI than the more commonly used severity scores (p < 0.01). Conclusion These results indicated that an increased blood glutamate level was closely related to the development of ALI and a poor prognosis after stroke. Clinical Trial Registration http://www.chictr.org.cn, identifier ChiCTR-RPC-15006770.

Impaired autophagic flux is associated with the severity of trauma and the role of A2AR in brain cells after traumatic brain injury

Recent studies have shown that after traumatic brain injury (TBI), the number of autophagosomes is markedly increased in brain cells surrounding the wound; however, whether autophagy is enhanced or suppressed by TBI remains controversial. In our study, we used a controlled cortical impact system to establish models of mild, moderate and severe TBI. In the mild TBI model, the levels of autophagy-related protein 6 (Beclin1) and autophagy-related protein 12 (ATG12)-autophagy-related protein 5 (ATG5) conjugates were increased, indicating the enhanced initiation of autophagy. Furthermore, the level of the autophagic substrate sequestosome 1 (SQSTM1) was decreased in the ipsilateral cortex. This result, together with the results observed in tandem mRFP-GFP-LC3 adeno-associated virus (AAV)-infected mice, indicates that autophagosome clearance was also increased after mild TBI. Conversely, following moderate and severe TBI, there was no change in the initiation of autophagy, and autophagosome accumulation was observed. Next, we used chloroquine (CQ) to artificially impair autophagic flux in the injured cortex of the mild TBI model and found that the severity of trauma was obviously exacerbated. In addition, autophagic flux and trauma severity were significantly improved in adenosine A2A receptor (A2AR) knockout (KO) mice subjected to moderate TBI. Thus, A2AR may be involved in regulating the impairment of autophagic flux in response to brain injury. Our findings suggest that whether autophagy is increased after TBI is associated with whether autophagic flux is impaired, and the impairment of autophagic flux exacerbates the severity of trauma. Furthermore, A2AR may be a target for alleviating the impairment in autophagic flux after TBI.