A Prospective Clinical Trial Measuring the Effects of Cardiopulmonary Bypass Under Mild Hypothermia on the Inflammatory Response and Regulation of Cold-Shock Protein RNA-Binding Motif 3

A comparison of bilateral and unilateral cerebral perfusion for total arch replacement surgery for non-marfan, type A aortic dissection

OBJECTIVES

Acknowledging lacking of consensus exist in total aortic arch (TAA) surgery for acute type A aortic dissection (AAD), this study aimed to investigate the neurologic injury rate between bilateral and unilateral cerebrum perfusion on the specific population.

METHODS

A total of 595 AAD patients other than Marfan syndrome receiving TAA surgery since March 2013 to March 2022 were included. Among them, 276 received unilateral cerebral perfusion (via right axillary artery, RCP) and 319 for bilateral cerebral perfusion (BCP). The primary outcome was neurologic injury rate. Secondary outcomes were 30-day mortality, serum inflammation response (high sensitivity C reaction protein, hs-CRP; Interleukin-6, IL-6; cold-inducible RNA binding protein, CIRBP) and neuroprotection (RNA-binding motif 3, RBM3) indexes.

RESULTS

The BCP group reported a significantly lower permanent neurologic deficits [odds ratio: 0.481, Confidence interval (CI): 0.296-0.782, p = 0.003] and 30-day mortality (odds ratio: 0.353, CI: 0.194-0.640, p < 0.001) than those received RCP treatment. There were also lower inflammation cytokines (hr-CRP: 114 ± 17 vs. 101 ± 16 mg/L; IL-6: 130 [103,170] vs. 81 [69,99] pg/ml; CIRBP: 1076 [889, 1296] vs. 854 [774, 991] pg/ml, all p < 0.001), but a higher neuroprotective cytokine (RBM3: 4381 ± 1362 vs 2445 ± 1008 pg/mL, p < 0.001) at 24 h after procedure in BCP group. Meanwhile, BCP resulted in a significantly lower Acute Physiology, Age and Chronic Health Evaluation (APACHE) Ⅱscore (18 ± 6 vs 17 ± 6, p < 0.001) and short stay in intensive care unit (4 [3,5] vs. 3 [2,3] days, p < 0.001) and hospital (16 ± 4 vs 14 ± 3 days, p < 0.001).

CONCLUSIONS

This present study indicated that BCP compared with RCP was associated with lower permanent neurologic deficits and 30-day mortality in AAD patients other than Marfan syndrome receiving TAA surgery.

Mild and deep hypothermia differentially affect cerebral neuroinflammatory and cold shock response following cardiopulmonary bypass in rat

INTRODUCTION

Targeted temperature management (TTM) is considered to be a neuroprotective strategy during cardiopulmonary bypass (CPB) assisted procedures, possibly through the activation of cold shock proteins. We therefore investigated the effects of mild compared with deep hypothermia on the neuroinflammatory response and cold shock protein expression after CPB in rats.

METHODS

Wistar rats were subjected to 1 hr of mild (33 °C) or deep (18 °C) hypothermia during CPB or sham procedure. PET scan analyses using TSPO ligand [11C]PBR28 were performed on day 1 (short-term) or day 3 and 7 post-procedure (long-term) to assess neuroinflammation. Hippocampal and cortical samples were obtained at day 1 in the short-term group and at day 7 in the long-term group. mRNA expression of M1 and M2 microglia associated cytokines was analysed with RT-PCR. Cold shock protein RNA-binding motive 3 (RBM3) and tyrosine receptor kinase B (TrkB) receptor protein expression were determined with Western Blot and quantified.

RESULTS

In both groups target temperature was reached within an hour. Standard uptake values (SUV) of [11C]PBR28 in CPB rats at 1 day and 3 days were similar to that of sham animals. At 7 days after CPB the SUV was significantly higher in amygdala and hippocampal regions of the CPB 18 °C group as compared to the CPB 33 °C group. No differences were observed in the expression of M1 and M2 microglia-related cytokines between TTM 18 °C and 33 °C. RBM3 protein levels in cortex and hippocampus were significantly higher in CPB 33 °C compared to CPB 18 °C and sham 33 °C, at day 1 and day 7, respectively.

CONCLUSIONS

TTM at 18 °C increased the neuroinflammatory response in amygdala and hippocampus compared to TTM at 33 °C in rats undergoing a CPB procedure. Additionally, TTM at 33 °C induced increased expression of TrkB and RBM3 in cortex and hippocampus of rats on CPB compared to TTM at 18 °C. Together, these data indicate that neuroinflammation is alleviated by TTM at 33 °C, possibly by recruiting protective mechanisms through cold shock protein induction.

Promising results of a clinical feasibility study: CIRBP as a potential biomarker in pediatric cardiac surgery

Objective

Cold-inducible RNA binding Protein (CIRBP) has been shown to be a potent inflammatory mediator and could serve as a novel biomarker for inflammation. Systemic inflammatory response syndrome (SIRS) and capillary leak syndrome (CLS) are frequent complications after pediatric cardiac surgery increasing morbidity, therefore early diagnosis and therapy is crucial. As CIRBP serum levels have not been analyzed in a pediatric population, we conducted a clinical feasibility establishing a customized magnetic bead panel analyzing CIRBP in pediatric patients undergoing cardiac surgery.

Methods

A prospective hypothesis generating observational clinical study was conducted at the German Heart Center Berlin during a period of 9 months starting in May 2020 (DRKS00020885, https://drks.de/search/de/trial/DRKS00020885). Serum samples were obtained before the cardiac operation, upon arrival at the pediatric intensive care unit, 6 and 24 h after the operation in patients up to 18 years of age with congenital heart disease (CHD). Customized multiplex magnetic bead-based immunoassay panels were developed to analyze CIRBP, Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), Interleukin-10 (IL-10), Monocyte chemotactic protein 1 (MCP-1), Syndecan-1 (SDC-1), Thrombomodulin (TM), Vascular endothelial growth factor (VEGF-A), Angiopoietin-2 (Ang-2), and Fibroblast growth factor 23 (FGF-23) in 25 µl serum using the Luminex MagPix® system.

Results

19 patients representing a broad range of CHD (10 male patients, median age 2 years, 9 female patients, median age 3 years) were included in the feasibility study. CIRBP was detectable in the whole patient cohort. Relative to individual baseline values, CIRBP concentrations increased 6 h after operation and returned to baseline levels over time. IL-6, IL-8, IL-10, and MCP-1 concentrations were significantly increased after operation and except for MCP-1 concentrations stayed upregulated over time. SDC-1, TM, Ang-2, as well as FGF-23 concentrations were also significantly increased, whereas VEGF-A concentration was significantly decreased after surgery.

Discussion

Using customized magnetic bead panels, we were able to detect CIRBP in a minimal serum volume (25 µl) in all enrolled patients. To our knowledge this is the first clinical study to assess CIRBP serum concentrations in a pediatric population.

Blood biomarker changes following therapeutic hypothermia in ischemic stroke

INTRODUCTION

Therapeutic hypothermia is a promising candidate for stroke treatment although its efficacy has not yet been demonstrated in patients. Changes in blood molecules could act as surrogate markers to evaluate the efficacy and safety of therapeutic cooling.

METHODS

Blood samples from 54 patients included in the EuroHYP-1 study (27 treated with hypothermia, and 27 controls) were obtained at baseline, 24 ± 2 h, and 72 ± 4 h. The levels of a panel of 27 biomarkers, including matrix metalloproteinases and cardiac and inflammatory markers, were measured.

RESULTS

Metalloproteinase-3 (MMP-3), fatty-acid-binding protein (FABP), and interleukin-8 (IL-8) increased over time in relation to the hypothermia treatment. Statistically significant correlations between the minimum temperature achieved by each patient in the hypothermia group and the MMP-3 level measured at 72 h, FABP level measured at 24 h, and IL-8 levels measured at 24 and 72 h were found. No differential biomarker levels were observed in patients with poor or favorable outcomes according to modified Rankin Scale scores.

CONCLUSION

Although the exact roles of MMP3, FABP, and IL-8 in hypothermia-treated stroke patients are not known, further exploration is needed to confirm their roles in brain ischemia.

RBM3 is associated with acute lung injury in septic mice and patients via the NF-κB/NLRP3 pathway

Sepsis refers to host response disorders caused by infection, leading to life-threatening organ dysfunction. RNA-binding motif protein 3 (RBM3) is an important cold-shock protein that is upregulated in response to mild hypothermia or hypoxia. In this study, we aimed to investigate whether RBM3 is involved in sepsis-associated acute lung injury (ALI). Intraperitoneal injection of LPS (10 mg/kg) was performed in wild type (WT) and RBM3 knockout (KO, RBM3-/-) mice to establish an in vivo sepsis model. An NLRP3 inflammasome inhibitor, MCC950 (50 mg/kg), was injected intraperitoneally 30 min before LPS treatment. Serum, lung tissues, and BALF were collected 24 h later for further analysis. In addition, we also collected serum from sepsis patients and healthy volunteers to detect their RBM3 expression. The results showed that the expression of RBM3 in the lung tissues of LPS-induced sepsis mice and the serum of patients with sepsis was significantly increased and positively correlated with disease severity. In addition, RBM3 knockout (KO) mice had a low survival rate, and RBM3 KO mice had more severe lung damage, inflammation, lung cell apoptosis, and oxidative stress than WT mice. LPS treatment significantly increased the levels of nucleotide binding and oligomerization domain-like receptor family 3 (NLRP3) inflammasomes and mononuclear cell nuclear factor-κB (NF-κB) in the lung tissues of RBM3 KO mice. However, these levels were only slightly elevated in WT mice. Interestingly, MCC950 improved LPS-induced acute lung injury in WT and RBM3 KO mice but inhibited the expression of NLRP3, caspase-1, and IL-1β. In conclusion, RBM3 was overexpressed in sepsis patients and LPS-induced mice. RBM3 gene deficiency aggravated sepsis-associated ALI through the NF-κB/NLRP3 pathway.

RBM3 is an outstanding cold shock protein with multiple physiological functions beyond hypothermia

RNA-binding motif protein 3 (RBM3), an outstanding cold shock protein, is rapidly upregulated to ensure homeostasis and survival in a cold environment, which is an important physiological mechanism in response to cold stress. Meanwhile, RBM3 has multiple physiological functions and participates in the regulation of various cellular physiological processes, such as antiapoptosis, circadian rhythm, cell cycle, reproduction, and tumogenesis. The structure, conservation, and tissue distribution of RBM3 in human are demonstrated in this review. Herein, the multiple physiological functions of RBM3 were summarized based on recent research advances. Meanwhile, the cytoprotective mechanism of RBM3 during stress under various adverse conditions and its regulation of transcription were discussed. In addition, the neuroprotection of RBM3 and its oncogenic role and controversy in various cancers were investigated in our review.

Mitochondrial Oxygenation During Cardiopulmonary Bypass: A Pilot Study

Objective

Adequate oxygenation is essential for the preservation of organ function during cardiac surgery and cardiopulmonary bypass (CPB). Both hypoxia and hyperoxia result in undesired outcomes, and a narrow window for optimal oxygenation exists. Current perioperative monitoring techniques are not always sufficient to monitor adequate oxygenation. The non-invasive COMET® monitor could be a tool to monitor oxygenation by measuring the cutaneous mitochondrial oxygen tension (mitoPO2). This pilot study examines the feasibility of cutaneous mitoPO2 measurements during cardiothoracic procedures. Cutaneous mitoPO2 will be compared to tissue oxygenation (StO2) as measured by near-infrared spectroscopy.

Design and Method

This single-center observational study examined 41 cardiac surgery patients requiring CPB. Preoperatively, patients received a 5-aminolevulinic acid plaster on the upper arm to enable mitoPO2 measurements. After induction of anesthesia, both cutaneous mitoPO2 and StO2 were measured throughout the procedure. The patients were observed until discharge for the development of acute kidney insufficiency (AKI).

Results

Cutaneous mitoPO2 was successfully measured in all patients and was 63.5 [40.0-74.8] mmHg at the surgery start and decreased significantly (p < 0.01) to 36.4 [18.4-56.0] mmHg by the end of the CPB run. StO2 at the surgery start was 80.5 [76.8-84.3]% and did not change significantly. Cross-clamping of the aorta and the switch to non-pulsatile flow resulted in a median cutaneous mitoPO2 decrease of 7 mmHg (p < 0.01). The cessation of the aortic cross-clamping period resulted in an increase of 4 mmHg (p < 0.01). Totally, four patients developed AKI and had a lower preoperative eGFR of 52 vs. 81 ml/min in the non-AKI group. The AKI group spent 32% of the operation time with a cutaneous mitoPO2 value under 20 mmHg as compared to 8% in the non-AKI group.

Conclusion

This pilot study illustrated the feasibility of measuring cutaneous mitoPO2 using the COMET® monitor during cardiothoracic procedures. Moreover, in contrast to StO2, mitoPO2 decreased significantly with the increasing CPB run time. Cutaneous mitoPO2 also significantly decreased during the aortic cross-clamping period and increased upon the release of the clamp, but StO2 did not. This emphasized the sensitivity of cutaneous mitoPO2 to detect circulatory and microvascular changes.

Effectiveness of Mild to Moderate Hypothermic Cardiopulmonary Bypass on Early Clinical Outcomes

BACKGROUND

Intraoperative hypothermia is an integral part of cardiopulmonary bypass (CPB), and a precise degree of hypothermia may improve the early clinical outcomes of cardiac surgery. Presently, there is no agreement on an accurate, advantageous temperature range for routine use in CPB. To address this issue, we conducted a retrospective observational study to compare the effects of different hypothermic temperature ranges on primary (inotropic support, blood loss, and platelet count) and secondary (ventilation support and in-hospital stay) outcomes in patients undergoing elective cardiac surgery.

METHODS

Data were retrieved from the medical database of the Cardiovascular Surgery Department, King Edward Medical University, Lahore-Pakistan (a tertiary care hospital), dating from February 2015 to December 2017. Patients were divided into mild (34 °C to 36 °C), intermediate (31 °C to 33 °C), or moderate (28 °C to 30 °C) hypothermic groups.

RESULTS

Out of 275 patients, 245 (89.09%) fit the inclusion criteria. The cohort with mild hypothermic CPB temperatures presented better clinical outcomes in terms of requiring less inotropic support, less blood loss, fewer blood transfusions, improved platelet counts, shorter in-hospital stays, and required less ventilation support, when compared with other hypothermic groups.

CONCLUSIONS

Mild hypothermic CPB (34 °C to 36 °C) may produce better clinical outcomes for cardiac surgery and improve the quality of health of cardiac patients.

RBM3 Increases Cell Survival but Disrupts Tight Junction of Microvascular Endothelial Cells in Acute Lung Injury

BACKGROUND

RNA-binding motif protein 3 (RBM3) is an important cold shock protein, which also responds to hypothermia or hypoxia. RBM3 is involved into multiple physiologic processes, such as promoting cell survival. However, its expression and function in acute lung injury (ALI) have not been reported.

METHODS

A mouse ALI model was established by lipopolysaccharides (LPS) treatment. The RBM3 and cold inducible RNA-binding protein mRNA levels were examined by RT-qPCR, and MMP9 mRNA stability was determined by actinomycin D assay. RBM3 and MMP9 mRNA was tested by RNA immunoprecipitation (RIP assay). RBM3 overexpression or silent stable cell lines were established using recombinant lentivirus and subsequently used for cell survival and tight junction measurements.

RESULTS

In this study, we found that RBM3, rather than cold inducible RNA-binding protein, was upregulated in lung tissue of ALI mice. RBM3 was increased in human pulmonary microvascular endothelial cells (HPMVECs) in response to LPS treatment, which is modulated by the NF-κB signaling pathway. Furthermore, RBM3 could reduce cell apoptosis induced by LPS, probably through suppressing p53 expression. Because increased permeability of HPMVECs leads to pulmonary edema in ALI, we subsequently examined the effect of RBM3 on cell tight junctions. Unexpectedly, RBM3 decreased the expression of tight junction protein zonula occludens-1 and increased cell permeability, and RBM3 overexpression increased MMP9 mRNA stability. Furthermore, RIP assay confirmed the interaction between RBM3 and MMP9 mRNA, possibly explaining the contribution of RBM3 to increase cell permeability.

CONCLUSIONS

RBM3 seems to act as a "double-edged sword" in ALI, that RBM3 alleviates cell apoptosis but increases HPMVEC permeability in ALI.

Role of RBM3 in the regulation of cell proliferation in hepatocellular carcinoma

RNA binding motif protein 3 (RBM3) has been shown to be upregulated in several types of human tumors. Using tissue microarrays and immunohistochemistry, we showed here that both nuclear and cytoplasmic RBM3 expression levels were higher in hepatocellular carcinoma (HCC) tissues than in adjacent non-tumorous tissues. High nuclear RBM3 was found to be correlated with larger tumor size (P = 0.030), high serum AFP levels (P = 0.011), and advanced Edmonson grading (P = 0.006). Cytoplasmic RBM3 was associated with advanced Edmonson grading (P = 0.003). Kaplan-Meier survival analysis revealed that, although not statistically significant, there was a trend toward shortened overall survival in the subset of HCC patients with high RBM3 expression (both nuclear and cytoplasmic). In addition, we found that RBM3 could promote YAP1 expression in HCC cells. Moreover, we found that YAP1 played an essential part in RBM3-induced proliferation of HCC cells. Furthermore, we demonstrated that Verteporfin, a YAP1 inhibitor, could repress RBM3-induced proliferation of HCC cells. Our findings provide a new experimental basis for further understanding of the possible role of RBM3-YAP1 in the regulation of HCC proliferation.

Effects of preoperative warming on the occurrence of surgical site infection: A systematic review and meta-analysis

OBJECTIVE

To determine whether preoperative warming can reduce the risk of surgical site infection (SSI) after surgery.

BACKGROUND

Intraoperative hypothermia is a risk factor for the occurrence of SSI in patients after surgery. However, the effectiveness of preoperative warming in reducing the incidence of the condition remains unclear.

MATERIALS AND METHODS

A systematic review was conducted using Medline, EMBASE, and the Cochrane Library to identify randomized controlled trials (RCTs) that evaluated the risk of SSI after surgery with and without the use of a preoperative warming protocol. The primary outcome measure was the diagnosis of SSI within 10-90 days of surgery. The pooled risk ratio was estimated with a fixed-effect meta-analysis. Sensitivity analyses were performed to examine the impact of the structural design of preoperative warming on the pooled risk of SSI.

RESULTS

Of the 249 studies identified, seven RCTs representing 1086 patients were included in the present meta-analysis. The use of preoperative warming was associated with a significant decrease in SSI (RR = 0.60, 95% CI 0.42-0.87, P = 0.072). Specifically, we defined patients who used forced-air warming (FAW) and integrated measures such as liquid heating and warming blankets as the MIX group and patients who used only FAW as the FAW group. Patients who used MIX methods (temperature set <43 °C and 30-min prewarming) before surgery benefited more from prewarming.

CONCLUSIONS

The results of this study suggest that preoperative warming can reduce rates of SSI after surgery. We, therefore, recommend the application of MIX warming methods before surgery.

Single-molecule measurements in microwells for clinical applications

The ability to detect and analyze proteins, nucleic acids, and other biomolecules is critical for clinical diagnostics and for understanding the underlying mechanisms of disease. Current detection methods in clinical and research laboratories rely upon bulk measurement techniques such as immunoassays, polymerase chain reaction, and mass spectrometry to detect these biomarkers. However, many potentially useful protein or nucleic acid biomarkers in blood, saliva, or other biofluids exist at concentrations well below the detection limits of current methods, necessitating the development of more sensitive technologies. Single-molecule measurements are poised to address this challenge, vastly improving sensitivity for detecting low abundance biomarkers and rare events within a population. Microwell arrays have emerged as a powerful tool for single-molecule measurements, enabling ultrasensitive detection of disease-relevant biomolecules in easily accessible biofluids. This review discusses the development, fundamentals, and clinical applications of microwell-based single-molecule methods, as well as challenges and future directions for translating these methods to the clinic.