Methysergide attenuates systemic burn edema in rats

A Next-Generation Sequencing of Plasma Exosome-Derived microRNAs and Target Gene Analysis with a Microarray Database of Thermally Injured Skins: Identification of Blood-to-Tissue Interactions at Early Burn Stage

BACKGROUND

Plasma exosome-derived microRNA (miRNA) profiles following thermal injury and their relationship with gene expression derangements in burned skin remain unexplored. This study focused on the identification of key miRNA-mRNA axes in potential blood-to-tissue interactions at early burn stage.

METHODS

Plasma exosomes were obtained from 6 severe burn patients 4-7 days post injury and 6 healthy volunteers. Next-generation sequencing (NGS) of exosomal small RNAs presented the differentially expressed miRNAs (DEMs). Target genes of the DEMs were predicted in the mirDIP database. Dataset GSE8056 was enrolled to acquire differentially expressed genes (DEGs) in burned skin compared to normal skin. Overlap between the DEGs and target genes of the DEMs were focus genes. The protein-protein interaction (PPI) network and enrichment analyses of the focus genes demonstrated hub genes and suggested underlying mechanisms and pathways. The hub genes and upstream DEMs were selected to construct key miRNA-mRNA axes.

RESULTS

The NGS of plasma exosome-derived small RNAs identified 85 DEMs (14 downregulated miRNAs and 71 upregulated miRNAs) with 12,901 predicted target genes. Dataset GSE8056 exhibited 1861 DEGs in partial-thickness burned skins 4-7 days postburn. The overlap between DEGs and target genes of DEMs displayed 1058 focus genes. The top 9 hub genes (CDK1, CCNB1, CCNA2, BUB1B, PLK1, KIF11, AURKA, NUSAP1 and CDCA8) in the PPI network of the focus genes pointed to 16 upstream miRNAs in DEMs, including 4 downregulated miRNAs (hsa-miR-6848-3p, has-miR-4684-3p, has-miR-4786-5p and has-miR-365a-5p) and 12 upregulated miRNAs (hsa-miR-6751-3p, hsa-miR-718, hsa-miR-4754, hsa-miR-6754-3p, hsa-miR-4739, hsa-miR-6739-5p, hsa-miR-6884-3p, hsa-miR-1224-3p, hsa-miR-6878-3p, hsa-miR-6795-3p, hsa-miR-550a-3p, and hsa-miR-550b-3p). A key miRNA-mRNA network in potential blood-to-tissue interactions at early burn stage was therefore constructed.

CONCLUSION

An NGS and bioinformatic analysis in the study identified key miRNA-mRNA axes in potential blood-to-tissue interactions at early burn stage, suggesting plasma exosome-derived miRNAs may impact on the alteration patterns of gene expressions in a burn wound.

Protective effect of puerarin against burn-induced heart injury in rats

The present study evaluated the potential protective effects of puerarin and its associated mechanism on burn-induced myocardial damage. A total of 40 healthy adult Wistar rats were randomly divided into four groups: i) Sham; ii) burn; iii) burn + puerarin; and iv) puerarin. Serum levels of interleukin (IL)-1β, tumor necrosis factor-α (TNF-α) and IL-6 were measured using ELISA. Myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels were determined in myocardial homogenates using a commercial assay kit. TUNEL staining and western blot analysis of cleaved and pro-caspase-3 were also performed to assess apoptosis. Activation of p38-MAPK, ERK, JNK and AKT were measured using western blot analysis. Left ventricular systolic pressure, maximum rates of increase/decrease in left ventricular pressure, creatine kinase MB activity and cardiac troponin T levels were found to be altered in the burn group 12 h after burn, which were reversed by puerarin treatment. Injection of puerarin following burn injury also reduced heart water content. Serum levels of IL-1β, TNF-α and IL-6 were significantly higher in the burn group compared with those in the sham group. Puerarin treatment reduced serum levels of IL-1β, TNF-α and IL-6, in addition to reducing MPO activity and MDA levels in myocardial tissues. Puerarin inhibited the activation of caspase-3, p38, ERK and JNK following severe burn, but elevated Akt activation following severe burn. In conclusion, puerarin improved cardiac function in rats following severe burn injury, which may be due to reduced myocardial injury, inhibition of cardiomyocyte apoptosis and reduced oxidative inflammatory stress; the MAPK and AKT signaling pathways are proposed to the underlying mechanism of these findings.

Identification and validation of uterine stimulant methylergometrine as a potential inhibitor of caspase-1 activation

Inflammasomes are intracellular multiprotein complexes of the innate immune system. Upon an inflammatory insult, such as infection or intracellular damage, a nucleotide-binding oligomerization domain-like receptor (NLR) sensor protein and the adaptor protein ASC (apoptosis-associated speck-like protein containing a caspase activation and recruitment domain) are assembled to activate protease procaspase-1. This protease processes pro-IL-1β and pro-IL-18 cytokines, which are released to induce the inflammatory response. De-regulation of inflammasome contributes to the progression of several diseases, such as Alzheimer’s disease, diabetes, cancer, inflammatory and autoimmune disorders. We herein describe the identification of methylergometrine (MEM), a drug currently used as a smooth muscle constrictor during postpartum hemorrhage, as an inhibitor of the inflammasome complex in ASC-mediated procaspase-1 activation screening. MEM inhibits the activation of the nucleotide-binding oligomerization domain-like receptor protein 1 (NLRP1) and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasomes in cellular models upon different pro-inflammatory stimuli. Our results suggest that MEM has the potential to reposition in the treatment of inflammatory diseases with the advantages of established safety and clinical data.

Influence of Cdp-Choline Administration on Early Burn Edema in Rats

PURPOSE

The cholinergic anti-inflammatory pathway may play an important role in early burn edema. Therefore, we evaluated the influence of cdp-choline on early systemic burn edema and leukocyte activation in shock in rat mesenteries after burn plasma transfer.

METHODS

Burn plasma harvested from donor rats 4 hours after thermal injury (30% total body surface area, 100°C water, 12 seconds) was administered intravenously to healthy animals during 2 hours of intravital microscopy. Shamburn plasma (same procedure but water at 37°C) was transferred for negative controls. In the study group, bolus injection of 100 mg/kg body weight cdp-choline was undertaken 15 minutes before examination. Intravital microscopy was performed in the ileal portion of rat mesenteries at 0, 60, and 120 minutes. Capillary leakage was assessed by fluorescein isothiocyanate-albumin extravasation and leukocyte-endothelial interaction were observed via transillumination microscopy. To assure comparable hemodynamic conditions, microhemodynamic parameters, foremost venular wall shear rate, were assessed.

RESULTS

Capillary leakage increased significantly after burn plasma transfer when compared to the shamburn group. Additional intravenous administration of cdp-choline attenuates macromolecular efflux to shamburn levels. Leukocyte activation is reduced after cdp-choline treatment.

CONCLUSIONS

The significant increase of albumin efflux in rat mesenteries after burn plasma transfer is decreased by additional cdp-choline bolus administration. Further investigations for proof of the relevance of the cholinergic anti-inflammatory pathway in early burn trauma are strongly required.

Assessment of edema volume in skin upon injury in a mouse ear model with optical coherence tomography

Accurate measurement of edema volume is essential for the investigation of tissue response and recovery following a traumatic injury. The measurements must be noninvasive and repetitive over time so as to monitor tissue response throughout the healing process. Such techniques are particularly necessary for the evaluation of therapeutics that are currently in development to suppress or prevent edema formation. In this study, we propose to use optical coherence tomography (OCT) technique to image and quantify edema in a mouse ear model where the injury is induced by a superficial-thickness burn. Extraction of edema volume is achieved by an attenuation compensation algorithm performed on the three-dimensional OCT images, followed by two segmentation procedures. In addition to edema volume, the segmentation method also enables accurate thickness mapping of edematous tissue, which is an important characteristic of the external symptoms of edema. To the best of our knowledge, this is the first method for noninvasively measuring absolute edema volume.

Puerarin attenuates severe burn-induced acute myocardial injury in rats

BACKGROUND

Puerarin, the main isoflavone glycoside extracted from the root of Pueraria lobata, is widely prescribed for patients with cardiovascular disorders in China. This study investigates the effect of puerarin on severe burn-induced acute myocardial injury in rats and its underlying mechanisms.

MATERIALS AND METHODS

Healthy adult Wistar rats were divided into three groups: (1) sham group, sham burn treatment; (2) burn group, third-degree burns over 30% of the total body surface area (TBSA) with lactated Ringer's solution for resuscitation; and (3) burn plus puerarin group, third-degree burns over 30% of TBSA with lactated Ringer's solution containing puerarin for resuscitation. The burned animals were sacrificed at 1, 3, 6, 12, and 24 h after burn injury. Myocardial injury was evaluated by analyzing serum creatine kinase MB fraction (CK-MB) activity and cardiac troponin T (cTNT) level. Changes in cardiomyocyte ultrastructure were also determined using a transmission electron microscope. Tumor necrosis factor (TNF)-α concentration in serum was measured by radioimmunoassay. Cardiac myeloperoxidase (MPO) activity and malondialdehyde (MDA) concentration were measured to determine neutrophil infiltration and oxidative stress in the heart, respectively. The expression of p38 mitogen-activated protein (MAP) kinase in the heart was determined by Western blot analysis.

RESULTS

After the 30% TBSA full-thickness burn injury, serum CK-MB activities and cTnT levels increased markedly, both of which were significantly decreased by the puerarin treatment. The level of serum TNF-α concentration in burn group at each time-point was obviously higher than those in sham group (1.09±0.09 ng/ml), and it reached the peak value at 12 h post burn. Burn trauma also resulted in worsen ultrastructural condition, elevated MPO activity and MDA content in heart tissue, and a significant activation of cardiac p38 MAP kinase. Administration of puerarin improved the ultrastructural changes in cardiomyocytes, decreased TNF-α concentration in serum as well as suppressed cardiac MPO activity and reduced MDA content, and abolished the activation of p38 MAP kinase in heart tissue after severe burn.

CONCLUSIONS

These results suggest that puerarin attenuates inflammatory responses, reduces neutrophil infiltration and oxidative stress in the heart, and protects against acute myocardial injury induced by severe burn.

5-HT2a receptor antagonism reduces burn-induced macromolecular efflux in rats

BACKGROUND

Major thermal injuries lead to a systemic inflammatory response with systemic capillary leakage and multiple organ dysfunction. This systemic inflammatory response is induced by a variety of immunmodulative molecules including TNFα and serotonin. Unspecific serotonin antagonism leads to reduced macromolecular efflux in rat mesenteries after burn plasma transfer. The aim of the present study was to evaluate the effect of specific 5-HT2a antagonism on early burn edema.

METHODS

Donor rats (DR) underwent thermal injury (100 °C water, 30% BSA, 12 s) for positive controls. For negative controls, DR underwent sham burn (37 °C water, 30% BSA, 12 s). DR plasma (harvested 4 h post-trauma) was transferred to healthy individuals for positive controls. Study rats received burn plasma (BP) and a Bolus injection of Ketanserin (Ket) (1 mg kg(-1) body weight). Negative controls underwent sham burn plasma infusion. Intravital microscopy was performed in mesenteric venules (0/60/120 min). Edema was assessed by FITC-albumin extravasation. Additionally, leukocyte rolling and sticking (cells mm(-2)) as well as microhemodynamic parameters were assessed.

RESULTS

Significant systemic capillary leakage was observed after BP transfer at 120 min and additional administration of Ket attenuated the postburn edema to sham burn levels. Ket also leads to significantly decreased leukocyte-endothelial interactions when compared to positive controls.

CONCLUSION

5-HT2a antagonism reduces plasma extravasation after burn plasma transfer in healthy individuals. The influence of leukocyte-endothelial interactions on postburn edema remains unclear.