Inhibition of TIM‐4 protects against cerebral ischaemia‐reperfusion injury

TIM‐4 plays an important role in ischaemia‐reperfusion injury of liver and kidney; however, the effects of TIM‐4 on cerebral ischaemia‐reperfusion injury (IRI) are unknown. The purpose of the present study was to investigate the potential role of TIM‐4 in experimental brain ischaemia‐reperfusion injury. In this study, cerebral ischaemia reperfusion was induced by transient middle cerebral artery occlusion (MCAO) for 1 hour in C57/BL6 mice. The TIM‐4 expression was detected in vivo or vitro by real‐time quantitative polymerase chain reaction, Western blot and flow cytometric analysis. In vivo, the administration of anti‐TIM‐4 antibodies significantly suppressed apoptosis, inhibited inflammatory cells and enhanced anti‐inflammatory responses. In vitro, activated microglia exhibited reduced cellular proliferation and induced IRI injury when co‐cultured with neurons; these effects were inhibited by anti‐TIM‐4 antibody treatment. Similarly, microglia transfected with TIM‐4 siRNA and stimulated by LPS + IFN‐γ alleviated the TIM‐4‐mediated damage to neurons. Collectively, our data indicate that the inhibition of TIM‐4 can improve the inflammatory response and exerts a protective effect in cerebral ischaemia‐reperfusion injury.     

Role of the p38 mitogen‐activated protein kinase signaling pathway in estrogen‐mediated protection following flap ischemia‐reperfusion injury

Ischemia‐reperfusion (I/R) injury often occurs during skin flap transplantation and results in tissue damage. Although estrogen treatment significantly alleviates this I/R injury‐induced damage, the detailed molecular mechanism is not clear. In this study, a superficial epigastric artery flap I/R injury model was created in adult Wistar rats. Severe necrosis was observed in skin tissue after I/R injury. Histological examination of skin tissue revealed that I/R injury damages skin structure and results in neutrophil infiltration. Inflammation‐related parameters, including neutrophil count, tumor necrosis factor‐α, and interleukin‐10 levels, were increased due to I/R injury. These pathological phenomena were reduced by estradiol treatment. Further investigation found that I/R injury triggers the p38 mitogen‐activated protein kinase (p38‐MAPK) pathway. The expression levels of p38‐MAPK and phosphorylated p38‐MAPK were increased after I/R injury. Estradiol increased the expression level of MAPK phosphatase‐2, a putative phosphatase of p38, and reduced the levels of p38‐MAPK and phosphorylated p38‐MAPK. These results suggest that estradiol can improve skin flap survival, possibly by inhibiting neutrophil infiltration and the expression of p38‐MAPK. This study provides an explanation for how estrogen alleviates I/R injury‐induced damage that occurs during skin flap transplantation. In a rat pathological model, I/R injury leads to skin necrosis, skin structure damage, neutrophil infiltration, and inflammatory cytokine secretion, which are probably downstream effects of activation of the p38‐MAPK pathway. On the other hand, estradiol treatment triggers the expression of MAPK phosphatase‐2, a putative phosphatase of p38‐MAPK, and reduced all examined pathological phenomena. Therefore, estrogen may reduce the deleterious effect of I/R injury on skin flap transplantation through modulating the p38‐MAPK pathway.     

Interaction of microbial pathogens with host exocytic pathways

Many microbial pathogens co‐opt or perturb host membrane trafficking pathways. This review covers recent examples in which microbes interact with host exocytosis, the fusion of intracellular vesicles with the plasma membrane. The bacterial pathogens Listeria monocytogenes and Staphylococcus aureus subvert recycling endosomal pathways of exocytosis in order to induce their entry into human cells. By contrast, entry of the protozoan pathogen Trypanosoma cruzi or the virus adenovirus into host cells involves exploitation of lysosomal exocytosis. Toxins produced by Bacillus anthracis or Vibrio cholerae interfere with exocytosis pathways mediated by the GTPase Rab11 and the exocyst complex. By doing so, anthrax or cholera toxins impair recycling of cadherins to cell–cell junctions and disrupt the barrier properties of endothelial cells or intestinal epithelial cells, respectively. Uropathogenic Escherichia coli (UPEC) is expelled from bladder epithelial cells through two different exocytic routes that involve sensing of bacteria in vacuoles by host Toll‐like receptor 4 (TLR4) or monitoring of the pH of lysosomes harbouring UPEC. The TLR4 pathway is mediated by multiple Rab GTPases and the exocyst, whereas the other pathway involves exocytosis of lysosomes. Expulsion of UPEC through these pathways is thought to benefit the host.     

LPS induces pulmonary intravascular macrophages producing inflammatory mediators via activating NF-kappaB

Pulmonary intravascular macrophages (PIMs) are often responsible for the clearance of blood-borne pathogens, including endotoxin, lipopolysaccharide of Gram-negative bacteria. It is well accepted that PIMs play a pivotal role in the pathogenesis of endotoxin-induced acute lung injury. However, the mechanisms by which PIMs are involved in the lipopolysaccharide-induced inflammatory responses remain unclear. Through the present study the following results were found: (1) When challenged with lipopolysaccharide (10 micrograms/ml), PIMs underwent marked cellular enlargement, intercellular adhesion plaques became longer, and some particulates were enwrapped in the pseudopods. (2) Lipopolysaccharide could up-regulate the expression of some inflammatory mediators in PIMs, including TNF-alpha, IL-1beta, IL-6, IL-8, and COX-2, and these up-regulated expression of inflammatory mediators correlated with NF-kappaB activation. (3) Dexamethasone as well as acetylsalicylic acid reduced the expression of TNF-alpha in lipopolysaccharide-challenged PIMs, and the decreased expression of TNF-alpha was also consistent with decreased NF-kappaB activation. Our results suggest that NF-kappaB activation in PIMs followed by phagocytizing lipopolysaccharide resulted in the up-regulation of TNF-alpha, IL-1beta, IL-6, IL-8, and COX-2, which could be alleviated by dexamethasone.     

Dl‐3‐n‐butylphthalide attenuates acute inflammatory activation in rats with spinal cord injury by inhibiting microglial TLR4/NF‐κB signalling

In this study, we examined the neuroprotective effects and anti‐inflammatory properties of Dl‐3‐n‐butylphthalide (NBP) in Sprague‐Dawley (SD) rats following traumatic spinal cord injury (SCI) as well as microglia activation and inflammatory response both in vivo and in vitro. Our results showed that NBP improved the locomotor recovery of SD rats after SCI an significantly diminished the lesion cavity area of the spinal cord, apoptotic activity in neurons, and the number of TUNEL‐positive cells at 7 days post‐injury. NBP inhibited activation of microglia, diminished the release of inflammatory mediators, and reduced the upregulation of microglial TLR4/NF‐κB expression at 1 day post‐injury. In a co‐culture system with BV‐2 cells and PC12 cells, NBP significantly reduced the cytotoxicity of BV‐2 cells following lipopolysaccharide (LPS) stimulation. In addition, NBP reduced the activation of BV‐2 cells, diminished the release of inflammatory mediators, and inhibited microglial TLR4/NF‐κB expression in BV‐2 cells. Our findings demonstrate that NBP may have neuroprotective and anti‐inflammatory properties in the treatment of SCI by inhibiting the activation of microglia via TLR4/NF‐κB signalling.     

Understanding the acid tolerance response of bifidobacteria

Aims: To investigate the effect of pH on the viability and the acid tolerance response (ATR) of bifidobacteria. Methods and Results: The impact of low pH on the viability of five species of bifidobacteria was examined under conditions of strict anaerobiosis. Although differences in the ability to resist the lethal effects of low pH were apparent among the species, cell viability could be improved by the provision of fermentable substrate during an acidic pH stress or through the use of stationary phase cells. While a stationary phase ATR was found to occur in two species of bifidobacteria, there was no adaptive response in exponential phase cells. Proteomic analysis of exponential phase Bifidobacterium longum subjected to a mild acid pre‐exposure (pH 4·5, 2 h) prior to an acid challenge revealed a substantial loss in the total number of cellular proteins. In contrast, proteomic analysis of stationary phase cells revealed an increased abundance of proteins associated with the general stress response as well as the β‐subunit of the F₀F₁‐ATPase, known to be important in bifidobacteria acid tolerance. Conclusion: Neither Bif. longum or Bifidobacterium breve possesses an inducible exponential phase ATR. Significance and Impact of the Study: These findings provide further insights into the impact of pH on the viability of bifidobacteria and may partially explain the loss in viability associated with their storage in acid foods.     

Proteomic identification of a novel isoform of collapsin response mediator protein-2 in spinal nerves peripheral to dorsal root ganglia

Primary afferent fibers are originated from pseudounipolar sensory cells in dorsal root ganglia (DRG) and transmit external stimuli received in the skin to the spinal cord. Here we undertook a proteomic approach to uncover the polarity of primary afferent fibers. Lumbar spinal nerve segments, peripheral and central to DRG, were dissected from 5-wk-old Wistar rats and the lysates were subjected to large-sized 2-DE at pH 5-6. Among approximately 800 protein spots detected in the central and peripheral fractions, one of the unique spots in the peripheral fraction with MW of 60 kDa and pI of 5.6 was identified as an isoform of collapsin response mediator protein-2 (CRMP-2) by MALDI-TOF MS and Western blots with anti-CRMP-2 antibodies that recognize 1-17 and 486-528 residues. Since this novel spot was detected only in the peripheral fraction, but not in the central fraction, DRG, and other regions of the brain, it was named periCRMP-2. The C-terminal fragment of CRMP-2 was not detected in periCRMP-2 by MS analyses. Expression of periCRMP-2 decreased following sciatic nerve injury. These results suggest that periCRMP-2 is a C-terminal truncated isoform polarized in the peripheral side of spinal nerves and may be involved in nerve degeneration and regeneration.     

Dangerous prey and daring predators: a review

How foragers balance risks during foraging is a central focus of optimal foraging studies. While diverse theoretical and empirical work has revealed how foragers should and do manage food and safety from predators, little attention has been given to the risks posed by dangerous prey. This is a potentially important oversight because risk of injury can give rise to foraging costs similar to those arising from the risk of predation, and with similar consequences. Here, we synthesize the literature on how foragers manage risks associated with dangerous prey and adapt previous theory to make the first steps towards a framework for future studies. Though rarely documented, it appears that in some systems predators are frequently injured while hunting and risk of injury can be an important foraging cost. Fitness costs of foraging injuries, which can be fatal, likely vary widely but have rarely been studied and should be the subject of future research. Like other types of risk‐taking behaviour, it appears that there is individual variation in the willingness to take risks, which can be driven by social factors, experience and foraging abilities, or differences in body condition. Because of ongoing modifications to natural communities, including changes in prey availability and relative abundance as well as the introduction of potentially dangerous prey to numerous ecosystems, understanding the prevalence and consequences of hunting dangerous prey should be a priority for behavioural ecologists.     

NB‐3 signaling mediates the cross‐talk between post‐traumatic spinal axons and scar‐forming cells

Little is known about the molecules mediating the cross‐talk between post‐traumatic axons and scar‐forming cells after spinal cord injury. We found that a sustained NB‐3 induction was simultaneously present in the terminations of post‐traumatic corticospinal axons and scar‐forming cells at the spinal lesion site, where they were in direct contact when axons tried to penetrate the glial scar. The regrowth of corticospinal axons was enhanced in vivo with NB‐3 deficiency or interruption of NB‐3 trans‐homophilic interactions. Biochemical, in vitro and in vivo evidence demonstrated that NB‐3 homophilically interacted in trans to initiate a growth inhibitory signal transduction from scar‐forming cells to neurons by modulating mTOR activity via CHL1 and PTPσ. NB‐3 deficiency promoted BMS scores, electrophysiological transmission, and synapse reformation between regenerative axons and neurons. Our findings demonstrate that NB‐3 trans‐homophilic interactions mediate the cross‐talk between post‐traumatic axons and scar‐forming cells and impair the intrinsic growth ability of injured axons.     

Long noncoding RNA TUG1 contributes to cerebral ischaemia/reperfusion injury by sponging mir‐145 to up‐regulate AQP4 expression

Emerging studies have shown that long noncoding RNA (lncRNA) TUG1 (taurine‐up‐regulated gene 1) plays critical roles in multiple biological processes. However, the expression and function of lncRNA TUG1 in cerebral ischaemia/reperfusion injury have not been reported yet. In this study, we found that LncRNA TUG1 expression was significantly up‐regulated in cultured MA‐C cells exposed to OGD/R injury, while similar results were also observed in MCAO model. Mechanistically, knockdown of TUG1 decreased lactate dehydrogenase levels and the ratio of apoptotic cells and promoted cell survival in vitro. Moreover, knockdown of TUG1 decreased AQP4 (encoding aquaporin 4) expression to attenuate OGD/R injury. TUG1 could interact directly with miR‐145, and down‐regulation of miR‐145 could efficiently reverse the function of TUG1 siRNA on AQP4 expression. Finally, the TUG1 shRNA reduced the infarction area and cell apoptosis in I/R mouse brains in vivo. In summary, our results suggested that lncRNA TUG1 may function as a competing endogenous RNA (ceRNA) for miR‐145 to induce cell damage, possibly providing a new therapeutic target in cerebral ischaemia/reperfusion injury.