Emboli formation rather than inflammatory mediators are responsible for increased cerebral water content after conventional and assisted beating-heart myocardial revascularization in a porcine model

Implantation of injectable SF hydrogel with sustained hydrogen sulfide delivery reduces neuronal pyroptosis and enhances functional recovery after severe intracerebral hemorrhage

Hydrogen sulfide (H₂S), an important endogenous signaling molecule, plays an important neuroprotective role in the central nervous system. However, there is no ideal delivery material or method involving the sustained and controlled release of H₂S for clinical application in brain diseases. Silk fibroin (SF)-based hydrogels have become a potentially promising strategy for local, controlled, sustained drug release in the treatment of various disorders. Here, we show a silk fibroin (SF)-based hydrogel with sustained H₂S delivery (H₂S@SF hydrogel) is effective in treating brain injury through stereotactic orthotopic injection in a severe intracerebral hemorrhage (ICH) mouse model. In this study, we observed H₂S@SF hydrogel sustained H₂S release in vitro and in vivo. The physicochemical properties of H₂S@SF hydrogel were studied using FE-SEM, Raman spectroscopy and Rheological analysis. Treatment with H₂S@SF hydrogel attenuated brain edema, reduced hemorrhage volume and improved the recovery of neurological deficits after severe ICH following stereotactic orthotopic injection. Double immunofluorescent staining also revealed that H₂S@SF hydrogel may reduce cell pyroptosis in the striatum, cortex and hippocampus. However, when using endogenous H₂S production inhibitor AOAA, H₂S@SF hydrogel could not suppress ICH-induced cell pyroptosis. Hence, the therapeutic effect of the H₂S@SF hydrogel may be partly the result of the slow-release of H₂S and/or the effect of the SF hydrogel on the production of endogenous H₂S. Altogether, the results exhibit promising attributes of injectable silk fibroin hydrogel and the utility of H₂S-loaded injectable SF hydrogel as an alternative biomaterial toward brain injury treatment for clinical application.

Silencing long non-coding RNA zinc finger antisense 1 restricts secondary cerebral edema and neuron injuries after traumatic brain injury

OBJECTIVE

To investigate the interaction of long non-coding RNA zinc finger antisense 1 (lncRNA ZFAS1) in secondary cerebral edema (CE) and neuron injuries after traumatic brain injury (TBI) in a mouse model.

METHODS

TBI mouse models was established by free-fall strike. Adeno-associated virus-short hairpin-ZFAS1 was administrated into mice via intracerebral injection to downregulate lncRNA ZFAS1. LncRNA ZFAS1 in mouse brain was examined. Neurological severity score (NSS), cerebral water content (CWC) and lesion volume were measured. The number of TUNEL-positive cells in brain tissue was accessed. Bax and cleaved caspase-3 in brain tissues were measured by western blot analysis, and pro-inflammatory factor levels were detected.

RESULTS

LncRNA ZFAS1 expression was upregulated in mouse brain tissues 3 days after TBI modelling. After the knockdown of lncRNA ZFAS1, NSS, CWC and lesion volume were decreased, apoptotic gene levels were decreased and pro-inflammatory cytokine levels were reduced, suggesting that lncRNA ZFAS1 knockdown could alleviate TBI-induced brain injuries in mice.

CONCLUSION

This study demonstrated that silencing lncRNA ZFAS1 inhibited TBI by quenching apoptosis, reducing inflammatory response and improving the recovery of neurological function in TBI mice. LncRNA ZFAS1 might function as a possible curative management in secondary CE and neuron injury in TBI mice.

Autophagy Activation Represses Pyroptosis through the IL-13 and JAK1/STAT1 Pathways in a Mouse Model of Moderate Traumatic Brain Injury

The newly highlighted research into programmed cell death (PCD), autophagy dependent cell death and pyroptotic cell death, has shown that these processes are both strongly correlated with the pathological progression of traumatic brain injury (TBI). However, their cross-talk in TBI remains unclear. Here, a moderate TBI model was established to explore the relationship between autophagy and pyroptosis. Rapamycin was used to activate the process of autophagy, which was impaired in the moderate TBI model, and this treatment reversed the expression of pyroptosis associated proteins, interleukin-13 (IL-13) and the pJAK-1 pathway, which were upregulated significantly after TBI. The level of IL-13 was downregulated, and the JAK-1 pathway was blocked to reveal the molecular mechanisms by which autophagy inhibits pyroptosis; these two treatments reduced the expression levels of pyroptosis associated proteins. In addition, these three interventions reduced the formation of neuronal NLRP3, the extent of brain edema, and the degree of cortical neuron degeneration. Furthermore, the deficit in motor function post-TBI was also markedly alleviated. Collectively, our results demonstrated that autophagy activation exerts a neuroprotective effect by inhibiting pyroptotic cell death in the moderate TBI model, and the inhibitory effect was dependent on the downregulation of IL-13 and repression of the JAK-1-STAT-1 signaling pathway.

Platelet regulates neuroinflammation and restores blood-brain barrier integrity in a mouse model of traumatic brain injury

Neuroinflammation accompanied by microglial activation triggers multiple cell death after traumatic brain injury (TBI). The secondary injury caused by inflammation may persist for a long time. Recently, platelet C-type lectin-like 2 receptor (CLEC-2) has been shown to regulate inflammation in certain diseases. However, its possible effects on TBI remain poorly understood. Here, we aimed to investigate the role of platelet CLEC-2 in the pathological process of neuroinflammation after TBI. In this study, mice were subjected to sham or controlled cortical impact injury, and arbitrarily received recombinant platelet CLEC-2. In parallel, BV2 cells were treated with lipopolysaccharide (LPS) to mimic microglial activation after TBI. Primary endothelial cells were also subjected to LPS in order to replicate the inflammatory damage caused by TBI. We used western blot analysis, reverse transcription polymerase chain reaction (RT-PCR), and immunostaining to evaluate the role of platelet CLEC-2 in TBI. In conditional knock out platelet CLEC-2 mice, trauma worsened the integrity of the blood-brain barrier and amplified the release of inflammatory cytokines. In wild type mice subjected to controlled cortical impact injury, recombinant platelet CLEC-2 administration altered the secretion of inflammatory cytokines, reduced brain edema, and improved neurological function. In vitro, the polarization phenotype of microglia induced by LPS was transformed by recombinant platelet CLEC-2, and this conversion depended on the mammalian target of rapamycin (mTOR) pathway. Endothelial cell injury by LPS was ameliorated when microglia expressed mostly M2 phenotype markers. In conclusion, platelet CLEC-2 regulates trauma-induced neuroinflammation and restores blood-brain barrier integrity.

Exogenous Hydrogen Sulfide Offers Neuroprotection on Intracerebral Hemorrhage Injury Through Modulating Endogenous H2S Metabolism in Mice

Hydrogen sulfide (H₂S), an important endogenous signaling molecule, has a significant neuroprotective role in the central nervous system. In this study, we examined the protective effects of exogenous H₂S against intracerebral hemorrhage (ICH), as well as its underlying mechanisms. We investigated the effects of exogenous H₂S on ICH using Western blotting, injury volume, measurement of brain edema, propidium iodide (PI) staining, and behavior assessment, respectively. We found that endogenous H₂S production was downregulated in the brain after ICH, which is caused by the decrease in cystathionine β-synthase (CBS) as the predominant cerebral H₂S-generating enzyme in the brain. Treatment with sodium hydrosulfide (NaHS; an H₂S producer) could restore the H₂S production and the expression of CBS. NaHS could also attenuate brain edema, injury volume, and neurological deficits in the Morris water maze test after ICH. Western blotting results indicated that H₂S pretreatment reversed the increase in caspase 3 cleavage and the decrease in Bcl-2, suppressed the activation of autophagy marker (LC3II and Beclin-1), and maintained the p62 level in injured striatum post-ICH. However, H₂S could not restore brain CBS expression and H₂S content, reduce brain edema, and improve motor performance and memory function after ICH through modulating autophagy and apoptosis when pretreated with the CBS inhibitor aminooxyacetic acid (AOAA). We also found that AOAA reduced the endogenous H₂S production through inhibiting the enzyme activity of CBS rather than modulating the expression of CBS protein level. These present results indicate that H₂S may possess potential therapeutic value in the treatment of brain injury after ICH, and the protective effect of exogenous H₂S against ICH may be not a direct action but an indirect effect through inducing endogenous H₂S metabolism responses.

Apelin-13 as a novel target for intervention in secondary injury after traumatic brain injury

The adipocytokine, apelin-13, is an abundantly expressed peptide in the nervous system. Apelin-13 protects the brain against ischemia/reperfusion injury and attenuates traumatic brain injury by suppressing autophagy. However, secondary apelin-13 effects on traumatic brain injury-induced neural cell death and blood-brain barrier integrity are still not clear. Here, we found that apelin-13 significantly decreases cerebral water content, mitigates blood-brain barrier destruction, reduces aquaporin-4 expression, diminishes caspase-3 and Bax expression in the cerebral cortex and hippocampus, and reduces apoptosis. These results show that apelin-13 attenuates secondary injury after traumatic brain injury and exerts a neuroprotective effect.

Managing the inflammatory response after cardiopulmonary bypass: review of the studies in animal models

Objective

To review studies performed in animal models that evaluated therapeutic interventions to inflammatory response and microcirculatory changes after cardiopulmonary bypass.

Methods

It was used the search strategy ("Cardiopulmonary Bypass" ^(MeSH)) and ("Microcirculation" ^(MeSH) or "Inflammation" ^(MeSH) or "Inflammation Mediators" ^(MeSH)). Repeated results, human studies, non-English language articles, reviews and studies without control were excluded.

Results

Blood filters, system miniaturization, specific primers regional perfusion, adequate flow and temperature and pharmacological therapies with anticoagulants, vasoactive drugs and anti-inflammatories reduced changes in microcirculation and inflammatory response.

Conclusion

Demonstrated efficacy in animal models establishes a perspective for evaluating these interventions in clinical practice.

Off-pump coronary artery bypass prevents visceral organ damage

OBJECTIVES

Visceral malperfusion after coronary artery bypass grafting (CABG) results in high morbidity and mortality. This study was designed to evaluate the effect of CABG performed by surgical techniques on visceral perfusion and function.

METHODS

Pigs (n = 28) were studied in four groups: I. Sham; II. Off-pump coronary artery bypass grafting (OPCAB): 1 h stabilizer with 40 min intracoronary shunt; III. Extracorporeal circulation (ECC): 1 h ECC with 40 min aortic cross-clamping and cardioplegic arrest; IV. Impella: 1 h left ventricular blood-pump support and stabilizer with 40 min intracoronary shunt. A left internal mammary to left anterior descending coronary artery bypass was performed in Groups II-IV. All animals were observed for a further 240 min. During the experiment haemodynamics, creatinine clearance, intestinal fatty acid binding protein (iFABP), pancreatic (lipase and amylase) and liver enzymes (α-glutathione s-transferase, glutamate-oxaloacetate transaminase (GOT), gamma-glutamyl transferase (GGT), glutamate dehydrogenase and glutamate-pyruvate transaminase (GPT)) were measured. Visceral perfusion (VP) was assessed in both kidneys, intestine, pancreas, liver and spleen with 15 µm fluorescent microspheres.

RESULTS

During OPCAB surgery, VP decreased slightly. Renal functional parameters, iFABP, pancreatic and liver enzymes remained unchanged. ECC and Impella led to significantly reduced renal, pancreatic and intestinal blood flow (P < 0.05). Creatinine clearance, pancreatic and liver (GPT, GGT) enzymes were significantly decreased only after ECC (P < 0.05). ECC and Impella resulted in a significantly increased iFABP level (P < 0.05). GOT was elevated significantly after surgery in Groups II, III and IV (P < 0.05).

CONCLUSIONS

CABG with ECC or Impella leads to impaired visceral blood flow and function. OPCAB minimizes these procedure associated alterations.

Hydrogen sulfide offers neuroprotection on traumatic brain injury in parallel with reduced apoptosis and autophagy in mice

Hydrogen sulfide (H₂S), a novel gaseous mediator, has been recognized as an important neuromodulator and neuroprotective agent in the central nervous system. The present study was undertaken to study the effects of exogenous H₂S on traumatic brain injury (TBI) and the underlying mechanisms. The effects of exogenous H₂S on TBI were examined by using measurement of brain edema, behavior assessment, propidium iodide (PI) staining, and Western blotting, respectively. Compared to TBI groups, H₂S pretreatment had reduced brain edema, improved motor performance and ameliorated performance in Morris water maze test after TBI. Immunoblotting results showed that H₂S pretreatment reversed TBI-induced cleavage of caspase-3 and decline of Bcl-2, suppressed LC3-II, Beclin-1 and Vps34 activation and maintained p62 level in injured cortex and hippocampus post TBI. The results suggest a protective effect and therapeutic potential of H₂S in the treatment of brain injury and the protective effect against TBI may be associated with regulating apoptosis and autophagy.

Poloxamer-188 attenuates TBI-induced blood-brain barrier damage leading to decreased brain edema and reduced cellular death

Plasmalemma permeability plays an important role in the secondary neuronal death induced by traumatic brain injury (TBI). Previous works showed that Poloxamer 188 (P188) could restore the intactness of the plasma membrane and play a cytoprotective action. However, the roles of P188 in blood-brain barrier (BBB) integrity and TBI-induced neural cell death are still not clear. In this study, mice were induced TBI by controlled cortical impact (CCI), and cerebral water content was measured to explore the profile of brain edema after CCI. Further, the regimen of P188 in mouse CCI models was optimized. The neurological test and BBB integrity assessment were performed, and the numbers of TBI-induced neural cell death were counted by propidium iodide (PI) labeling. The expression of apoptotic pathway associated proteins (Bax, cyt-c, caspase-8, caspase-9, caspase-3, P53) and aquaporin-4 (AQP4) was assessed by RT-PCR or immunoblotting. The data showed that the brain edema peaked at 24 h after TBI in untreated animals. Tail intravenous injection of P188 (4 mg/ml, 100 μl) 30 min before TBI or within 30 min after TBI could attenuate TBI-induced brain edema. P188 pre-treatment restored BBB integrity, suppressed TBI-induced neural cell death, and improved neurological function. TBI induced an up-regulation of Bax, cyt-c, caspase-8, caspase-9, caspase-3, and the expression of p53 was down-regulated by P188 pre-treatment. AQP4 mainly located on endothelial cells and astrocytes, and its expression was also regulated by P188 pretreatment. All these results revealed that P188 attenuates TBI-induced brain edema by resealing BBB and regulating AQP4 expression, and suppressed apoptosis through extrinsic or intrinsic pathway. Plasmalemma permeability may be a potential target for TBI treatment.

[The influence of cardiopulmonary bypass operation on the biodistribution of 99mTc-HMPAO-labelled granulocytes - Evaluation in pigs by planar scintigraphy and section-analyses]

AIM

of the study was to evaluate the influence of an extra corporal perfusion (cardiopulmonary bypass operation - cpb) on activation and biodistribution of (99m)Tc labelled granulocytes in pigs with and without inhibition of the granulocytes by a leukocyte inhibition module (LIM). The cpb is often related to an activation of granulocytes resulting in an inflammatory answer. The biological mechanisms are unsolved yet. First trials of our group showed that LIM may inhibit the activation of neutrophils and therefore antagonize a cpb-caused impairment of cardiac function. This study is the continuation of these experiments with a higher number of animals and the focus on scintigraphic imaging. ANIMALS, MATERIAL, METHODS: 39 German landrace pigs were subdivided into three groups: group A (control) median sternotomy without cpb, group B with cpb, group C with LIM in addition to cpb. After labelling with (99m)Tc-HMPAO autologues granulocytes were reinjected. Subsequently to cpb, the animals underwent scintigraphic imaging. Quantification was performed with ROI evaluation and with tissue samples (section analysis) examined in a well counter.

RESULTS

A high uptake of (99m)Tc-HMPAO was found in the liver. The count rates in brain, heart, lung, spleen and kidneys were far below. The amount of 99mTc-activity in the organ related to the half life corrected administered activity [%] was for the tissue samples (group A/B/C): brain 0.01/0.02/0.03; lung 12.1/8.3/11.5; heart 0.35/0.54/0.42; kidney 1.24/0.87/1.02; spleen 4.0/4.0/4.5, liver 16.8/20.9/19.6. The count rates determined by ROI-evaluation of the scintigraphic images related to the total count rate in the image [%] were (group A/B/C): brain 1.1/0.9/1.0; lung 15.6/10.4/12.2; heart 4.0/3.5/3.4; kidney 4.0/2.9/3.2; spleen 7.6/7.7/9.5, liver 23.1/36.7/31.4. A significant difference in the tracer uptake between the groups could neither be detected by scintigraphic imaging nor evaluation of tissue samples.

CONCLUSION

Scintigraphic imaging as well as section analysis showed a comparable biodistribution of the tracer. Therefore, the initial results of our group were not confirmed with a considerably higher number of animals. Neither cpb nor the use of the LIM influenced distribution of 99mTc-labelled granulocytes in pigs significantly.

Emboli occurrence during coronary artery bypass surgery: the influence of a new method of perfusionist blood sampling

Peri-operative cerebral microemboli in cardiac surgery are associated with post-operative neurological complications. Cardiopulmonary bypass (CPB) and perfusionist interventions are important contributors of microemboli. In this study, we examined the influence of blood sampling by the perfusionist on the appearance of microembolic signals (MES) in an open and a closed CPB system. Fourteen patients underwent isolated coronary artery bypass grafting (CABG), using either an open or closed CPB system. Patients were monitored with transcranial Doppler (TCD) for the occurrence MES in both middle cerebral arteries (MCA) as well as in the arterial and venous lines of the CPB. In the closed system, two sampling methods were used, namely the “traditional” and the “E-line”. In the latter, a shunt line was applied from the manifold to the cardiotomy reservoir). In the open system, one method of blood sampling was used. Blood sampling in an open system or in a closed system using the E-line resulted in 0.2 (±0.56) MES, which was significantly lower than the traditional method (72 (±69) MES). The use of a shunt line reduces MES during blood sampling in a closed CPB system.