Serum CIRP increases the risk of acute kidney injury after cardiac surgery.

Introduction: Acute kidney injury (AKI) is a frequent perioperative complication. The underlying mechanisms of cardiac surgery-associated AKI are still not completely elucidated. Cold-induced RNA-binding protein (CIRP) has been subsequently found to be regulated by various stress conditions. During cardiac surgery and cardiopulmonary bypass (CPB), the host is subjected to hypothermia and inadequate organ perfusion, resulting in an upregulation of CIRP secretion. The aim of this study is to evaluate the role of elevated extracellular CIRP level as a contributing factor in the development of AKI. Methods: A total of 292 patients who underwent cardiac surgery were retrospectively enrolled and their serum samples were collected preoperative and postoperative. Demographic data, intraoperative data, in-hospital outcomes, and the occurrence of AKI were also collected for the patients. The correlation between CIRP and intraoperative procedures, as well as its association with postoperative outcomes were analyzed. Results: In multivariable analysis, higher ΔCIRP (p = 0.036) and body mass index (p = 0.015) were independent risk factors for postoperative AKI. Meanwhile, patients with postoperative AKI exhibited lower survival rate in 2-year follow-up (p = 0.008). Compared to off-pump coronary artery bypass grafting surgery, patients who underwent on-pump coronary artery bypass grafting, valve surgery, aortic dissection and other surgery showed higher ΔCIRP, measuring 1,093, 666, 914 and 258 pg/mL, respectively (p < 0.001). The levels of ΔCIRP were significantly higher in patients who underwent CPB compared to those who did not (793.0 ± 648.7 vs. 149.5 ± 289.1 pg/mL, p < 0.001). Correlation analysis revealed a positive correlation between ΔCIRP levels and the duration of CPB (r = 0.502, p < 0.001). Patients with higher CIRP levels are at greater risk of postoperative AKI (OR: 1.67, p = 0.032), especially the stage 2-3 AKI (OR: 2.11, p = 0.037). Conclusion: CIRP secretion increases with prolonged CPB time after cardiac surgery, and CIRP secretion is positively correlated with the duration of CPB. Cardiac surgeries with CPB exhibited significantly higher levels of CIRP compared to non-CPB surgeries. Elevation of CIRP level is an independent risk factor for the incidence of AKI, especially the severe AKI, and were associated with adverse in-hospital outcomes.

Transcriptome analysis reveals molecular mechanisms responsive to acute cold stress in the tropical stenothermal fish tiger barb (Puntius tetrazona).

BACKGROUND: Tropical stenothermal fish exhibit special tolerance and response to cold stress. However current knowledge of the molecular mechanisms response to cold stress in aquatic ectotherms is largely drawn from eurythermal or extreme stenothermal species. The tiger barb Puntius tetrazona is a tropical stenothermal fish, with great popularity in aquarium trade and research. RESULTS: To investigate the response mechanism of P. tetrazona to low temperature, fish were exposed to increasing levels of acute cold stress. Histopathological analysis showed that the brain, gill, liver and muscle tissues appeared serious damage after cold stress (13 °C). Brain, gill, liver and muscle tissues from control (CTRL) groups (27 °C) and COLD stress groups (13 °C) of eight-month fish (gender-neutral) were sampled and assessed for transcriptomic profiling by high-throughput sequencing. 83.0 Gb of raw data were generated, filtered and assembled for de novo transcriptome assembly. According to the transcriptome reference, we obtained 392,878 transcripts and 238,878 unigenes, of which 89.29% of the latter were annotated. There were 23,743 differently expressed genes (DEGs) been filtered from four pairs of tissues (brain, gill, liver and muscle) between these cold stress and control groups. These DEGs were mainly involved in circadian entrainment, circadian rhythm, biosynthesis of steroid and fatty acid. There were 64 shared DEGs between the four pairs of groups, and five were related to ubiquitylation/deubiquitylation. Our results suggested that ubiquitin-mediated protein degradation might be necessary for tropical stenothermal fish coping with acute cold stress. Also, the significant cold-induced expression of heat shock 70 kDa protein (HSP70) and cold-induced RNA-binding protein (CIRBP) was verified. These results suggested that the expression of the molecular chaperones HSP70 and CIRBP in P. tetrazona might play a critical role in coping with acute cold stress. CONCLUSIONS: This is the first transcriptome analysis of P. tetrazona using RNA-Seq technology. Novel findings about tropical stenothermal fish under cold stress (such as HSP70 and CIRBP genes) are presented here. This study contributes new insights into the molecular mechanisms of tropical stenothermal species response to acute cold stress.

Cold-inducible RNA-binding protein contributes to intracerebral hemorrhage-induced brain injury via TLR4 signaling.

INTRODUCTION: Excessive neuroinflammation aggravates the brain injury caused by intracerebral hemorrhage (ICH), while the upstream mechanisms that initiate neuroinflammation remain unclear. Toll-like receptor 4 (TLR4) signaling is important to trigger inflammatory responses in ICH, and cold-inducible RNA-binding protein (CIRP) has been shown as a novel ligand of TLR4 by recent studies. However, whether the CIRP could trigger the neuroinflammation via activating TLR4 signaling in ICH still needs to be investigated. METHODS: Human serum CIRP levels were measured using the ELISA kits. Western blot, FJB staining, brain water content, and neurological deficit scores were used to investigate the roles of CIRP in brain injury caused by ICH. RESULT: First, we found increased CIRP levels in the blood of patients with ICH when compared to the control individuals, and the ICH patients with mRS > 2 have higher serum CIRP levels in contrast to those with mRS ≤ 2. In the ICH mice, we also found that brain CIRP protein and mRNA levels were also increased after ICH. Furthermore, using the CIRP-/- mice, we found that CIRP-/- mice had less brain damages showing in less FJB+ cells, reduced brain water content (BWC) and lower neurological deficit scores (NDS) compared to that in WT mice after ICH. Cytokines including IL-6, TNF-α, and IL-1ß from CIRP-/- mice were attenuated after ICH. CIRP-/- mice also exhibited reduced TLR4 expression which was accompanied by the decreased activity of NF-κB. This suggests that TLR4 signaling might be involved in CIRP-mediated inflammatory injury possibly via NF-κB activation after ICH. CONCLUSION: Our findings suggest that CIRP may activate TLR4 signaling, and further inducing NF-κB activation to increase the expression levels of cytokines and aggravate inflammatory injury in ICH. Targeting CIRP may be a promising strategy for ICH treatment.

Effects of cold induced RNA binding protein on hippocampal neurons and mitochondrial damage after mild hypothermia in a rat model of cardiac arrest / 医学研究生学报

ObjectiveMild hypothermia was an effective way of cerebral resuscitation after cardiac arrest. The expression of cold-induced RNA binding protein (CIRP) was significantly enhanced when the temperature was lowered. This study was to evaluate the effects and the mechanisms of CIRP inhibition on hippocampal neurological and mitochondria function after mild hypothermia in a rat model of cardiac arrest.MethodsFive male Sprague-Dawley rats were injected with AAV9 in the hippocampus, 1 μL on each side, speeding 0.2 μL/min. The expression of GFP was observed by fluorescence microscopy after 2w. Sixty rats were randomly divided into 5 groups (n= 12 for each group): sham operation group, model group, mild hypothermia group, mild hypothermia + CIRP inhibition group and mild hypothermia + normal control group. Injection of AAV9 was performed on mild hypothermia + CIRP inhibition group, same amount of empty vector on mild hypothermia + normal control group, while normal saline on the other groups. Animal models of global cerebral IR were established by transesophageal cardiac pacing inducing cardiac arrest followed by cardiopulmonary resuscitation at 2w after injection. Cooling to 32-34℃ was initiated and the temperature was maintained for 6h on mild hypothermia groups. NDS score, HE staining and pyramidal cell counting on hippocampal CA1 area were performed at 72h after reperfusion. At 24h after reperfusion, mitochondrial structure of pyramidal cells in hippocampal CA1 was observed under electronic microscope and the expressions of CIRP, dynamin-related protein 1 (Drp1) and cytochrome C (Cyt-C) were detected by Western blot.ResultsThe NDS score of model group was decreased, the number of pyramidal cells was reduced, and the mitochondria were severely damaged. The NDS score of mild hypothermia group was increased, and the number of pyramidal cells was increased (all P<0.05), and mitochondrial damage was reduced compared with model group. In mild hypothermia + CIRP inhibition group, the NDS score was no significant difference compared with mild hypothermia + normal control group and model group, and the number of pyramidal cells was lower than that in mild hypothermia + normal control group [(27.2±4.9) vs (50.2±4.4), P<0.05], similar to model group (25.2±3.8), the damage of mitochondria was severe. After 2 weeks of AAV9 injection, GFP was widely expressed in the hippocampus. The expression of CIRP in mild hypothermia + CIRP inhibition group was respectively small compared with sham operation group [(0.14±0.03) vs (0.03±0.01),P<0.05], which was successfully inhibited by injection of AAV9. The expression of CIRP in model group (0.25±0.05) was significantly higher than that in sham operation group. The expression of CIRP in mild hypothermia group (0.37±0.08) and mild hypothermia + normal control group (0.39±0.04) were higher than that in model group (all P<0.05). The trends of Drp1 and Cyt-C expression were the same, in model group was higher than that in sham operation group, in mild hypothermia group was lower than that in model group, in mild hypothermia + CIRP inhibition group was higher than in mild hypothermia + normal control group (all P<0.05); There were no significant differences between model group and mild hypothermia + CIRP inhibition group, and between mild hypothermia group and mild hypothermia + normal control group.ConclusionInhibition of CIRP expression in hippocampus can weaken the protective effects of mild hypothermia on neurons in a rat model of cardiac arrest. The mechanism of those effects might be association with mitochondrial division.

Transcriptional Profiling of Cholinergic Neurons From Basal Forebrain Identifies Changes in Expression of Genes Between Sleep and Wake.

Study objective: To assess differences in gene expression in cholinergic basal forebrain cells between sleeping and sleep-deprived mice sacrificed at the same time of day. Methods: Tg(ChAT-eGFP)86Gsat mice expressing enhanced green fluorescent protein (eGFP) under control of the choline acetyltransferase (Chat) promoter were utilized to guide laser capture of cholinergic cells in basal forebrain. Messenger RNA expression levels in these cells were profiled using microarrays. Gene expression in eGFP(+) neurons was compared (1) to that in eGFP(-) neurons and to adjacent white matter, (2) between 7:00 am (lights on) and 7:00 pm (lights off), (3) between sleep-deprived and sleeping animals at 0, 3, 6, and 9 hours from lights on. Results: There was a marked enrichment of ChAT and other markers of cholinergic neurons in eGFP(+) cells. Comparison of gene expression in these eGFP(+) neurons between 7:00 am and 7:00 pm revealed expected differences in the expression of clock genes (Arntl2, Per1, Per2, Dbp, Nr1d1) as well as mGluR3. Comparison of expression between spontaneous sleep and sleep-deprived groups sacrificed at the same time of day revealed a number of transcripts (n = 55) that had higher expression in sleep deprivation compared to sleep. Genes upregulated in sleep deprivation predominantly were from the protein folding pathway (25 transcripts, including chaperones). Among 42 transcripts upregulated in sleep was the cold-inducible RNA-binding protein. Conclusions: Cholinergic cell signatures were characterized. Whether the identified genes are changing as a consequence of differences in behavioral state or as part of the molecular regulatory mechanism remains to be determined.