Blood Indices In Adult Acute Burn: A Window Into Milieu Interieur - The Future Biomarkers?

Optimal treatment of sepsis in burned patients depends on early diagnosis and includes prompt administration of antimicrobials as well as management of hemodynamic alterations and other organ dysfunctions. The role of red blood cell distribution width (RDW) and platelet indices in prognosticating and identifying sepsis in acute burn patients is studied. This study was done as a prospective study over 18 months, including patients in the age group >18 or <60 years, with burns >20% and <70% TBSA, burn time to resuscitation time 24 hours or less and with thermal and scald burns. Data of 157 patients were analyzed and the following observations were made. The mean age of the study population was 31.36 years (18-59 years). RDW values were higher in the non-survivor group. Platelet count and plateletcrit were higher in the survivor group and the no sepsis group. Positive rising trends of platelet count and plateletcrit were seen in the survivor group. Day 1, 3, 7 values of RDW, platelet count and plateletcrit were significant in determining the outcome of the patient on mortality and sepsis related morbidity of the patient. RDW, platelet count and plateletcrit in combination can predict mortality and sepsis as early as the third day, thus giving a clinical advantage of initiating targeted treatment to the at-risk burn population before sepsis is detected clinically. This could better the outcomes in treatment of burn patients.

Blood Lactate And Lactate Clearance: Refined Biomarker And Prognostic Marker In Burn Resuscitation

Adequate resuscitation of acute burn patients is important to ensure end organ perfusion and oxygenation. The ideal marker to the endpoint of burn resuscitation is still not established. We aimed to evaluate the role of blood lactate and lactate clearance in burn resuscitation and their association with mortality and sepsis in burn patients. The retrospective study included patients (18-50 years) with thermal and scald burns with total body surface area of 30% to 60% over a period of 9 months who had achieved target urine output of at least 0.5ml/kg/hr within 24 hours of resuscitation. Patients were divided based on their admission blood lactate levels (Group A < 2 mmol/L and Group B > 2 mmol/L). Group B was further subdivided into Group B1 in whom blood lactate levels reached less than 2 mmol/L within 24 hours of burn resuscitation and Group B2 in whom it did not. Total patients included were 203. Mortality (M) and sepsis (S) rates in subgroup B2 were higher (M=57.9%; S=43.5%) and rates in subgroup B1 (M=25.8%; S=27.4%) were comparable to Group A (M=27.8%; S=26.4%). Persistent lactic acidosis at 24 hours was independently associated with significantly increased mortality and sepsis. Our data suggests a correlation of blood lactate levels and lactate clearance within 24 hours of admission with mortality and sepsis related to burn injury.

The chromatin-remodeling enzyme CHD3 plays a role in embryonic viability but is dispensable for early vascular development

ATP-dependent chromatin-remodeling complexes epigenetically modulate transcription of target genes to impact a variety of developmental processes. Our lab previously demonstrated that CHD4-a central ATPase and catalytic enzyme of the NuRD chromatin-remodeling complex-plays an important role in murine embryonic endothelial cells by transcriptionally regulating vascular integrity at midgestation. Since NuRD complexes can incorporate the ATPase CHD3 as an alternative to CHD4, we questioned whether the CHD3 enzyme likewise modulates vascular development or integrity. We generated a floxed allele of Chd3 but saw no evidence of lethality or vascular anomalies when we deleted it in embryonic endothelial cells in vivo (Chd3ECKO). Furthermore, double-deletion of Chd3 and Chd4 in embryonic endothelial cells (Chd3/4ECKO) did not dramatically alter the timing and severity of embryonic phenotypes seen in Chd4ECKO mutants, indicating that CHD3 does not play a cooperative role with CHD4 in early vascular development. However, excision of Chd3 at the epiblast stage of development with a Sox2-Cre line allowed us to generate global heterozygous Chd3 mice (Chd3Δ/+), which were subsequently intercrossed and revealed partial lethality of Chd3Δ/Δ mutants prior to weaning. Tissues from surviving Chd3Δ/Δ mutants helped us confirm that CHD3 was efficiently deleted in these animals and that CHD3 is highly expressed in the gonads and brains of adult wildtype mice. Therefore, Chd3-flox mice will be beneficial for future studies about roles for this chromatin-remodeling enzyme in viable embryonic development and in gonadal and brain physiology.

Cell-specific and athero-protective roles for RIPK3 in a murine model of atherosclerosis

Receptor-interacting protein kinase 3 (RIPK3) was recently implicated in promoting atherosclerosis progression through a proposed role in macrophage necroptosis. However, RIPK3 has been connected to numerous other cellular pathways, which raises questions about its actual role in atherosclerosis. Furthermore, RIPK3 is expressed in a multitude of cell types, suggesting that it may be physiologically relevant to more than just macrophages in atherosclerosis. In this study, Ripk3 was deleted in macrophages, endothelial cells, vascular smooth muscle cells or globally on the Apoe-/- background using Cre-lox technology. To induce atherosclerosis progression, male and female mice were fed a Western diet for three months before tissue collection and analysis. Surprisingly, necroptosis markers were nearly undetectable in atherosclerotic aortas. Furthermore, en face lesion area was increased in macrophage- and endothelial-specific deletions of Ripk3 in the descending and abdominal regions of the aorta. Analysis of bone-marrow-derived macrophages and cultured endothelial cells revealed that Ripk3 deletion promotes expression of monocyte chemoattractant protein 1 (MCP-1) and E-selectin in these cell types, respectively. Western blot analysis showed upregulation of MCP-1 in aortas with Ripk3-deficient macrophages. Altogether, these data suggest that RIPK3 in macrophages and endothelial cells protects against atherosclerosis through a mechanism that likely does not involve necroptosis. This protection may be due to RIPK3-mediated suppression of pro-inflammatory MCP-1 expression in macrophages and E-selectin expression in endothelial cells. These findings suggest a novel and unexpected cell-type specific and athero-protective function for RIPK3.This article has an associated First Person interview with the first author of the paper.

The NuRD chromatin-remodeling complex enzyme CHD4 prevents hypoxia-induced endothelial Ripk3 transcription and murine embryonic vascular rupture

Physiological hypoxia can trigger transcriptional events that influence many developmental processes during mammalian embryogenesis. One way that hypoxia affects transcription is by engaging chromatin-remodeling complexes. We now report that chromodomain helicase DNA binding protein 4 (CHD4), an enzyme belonging to the nucleosome remodeling and deacetylase (NuRD) chromatin-remodeling complex, is required for transcriptional repression of the receptor-interacting protein kinase 3 (Ripk3)-a critical executor of the necroptosis cell death program-in hypoxic murine embryonic endothelial cells. Genetic deletion of Chd4 in murine embryonic endothelial cells in vivo results in upregulation of Ripk3 transcripts and protein prior to vascular rupture and lethality at midgestation, and concomitant deletion of Ripk3 partially rescues these phenotypes. In addition, CHD4 binds to and prevents acetylation of the Ripk3 promoter in cultured endothelial cells grown under hypoxic conditions to prevent excessive Ripk3 transcription. These data demonstrate that excessive RIPK3 is detrimental to embryonic vascular integrity and indicate that CHD4 suppresses Ripk3 transcription when the embryonic environment is particularly hypoxic prior to the establishment of fetal-placental circulation at midgestation. Altogether, this research provides new insights into regulators of Ripk3 transcription and encourages future studies into the mechanism by which excessive RIPK3 damages embryonic blood vessels.

BRG1 (Brahma-Related Gene 1) Promotes Endothelial Mrtf Transcription to Establish Embryonic Capillary Integrity

OBJECTIVE

The chromatin remodeling enzyme BRG1 (brahma-related gene 1) transcriptionally regulates target genes important for early blood vessel development and primitive hematopoiesis. However, because Brg1 deletion in vascular progenitor cells results in lethal anemia by embryonic day 10.5 (E10.5), roles for BRG1 in embryonic vascular development after midgestation are unknown. In this study, we sought to determine whether endothelial cell BRG1 regulates genes important for vascular development or maintenance later in embryonic development.

APPROACH AND RESULTS

Using mice with temporally inducible deletion of endothelial BRG1 (Brg1^fl/fl;Cdh5(PAC)-Cre^ERT2 ), we found that Brg1 excision between E9.5 and 11.5 results in capillary dilation and lethal hemorrhage by E14.5. This phenotype strongly resembles that seen when the SRF (serum response factor) transcription factor is deleted from embryonic endothelial cells. Although expression of Srf and several of its known endothelial cell target genes are downregulated in BRG1-depleted endothelial cells, we did not detect binding of BRG1 at these gene promoters, indicating that they are not direct BRG1 target genes. Instead, we found that BRG1 binds to the promoters of the SRF cofactors Mrtfa and Mrtfb (myocardin-related transcription factors A and B) in endothelial cells, and these genes are downregulated in Brg1-deficient endothelial cells.

CONCLUSIONS

BRG1 promotes transcription of endothelial Mrtfa and Mrtfb, which elevates expression of SRF and SRF target genes that establish embryonic capillary integrity. These data highlight a new and temporally specific role for BRG1 in embryonic vasculature and provide novel information about epigenetic regulation of Mrtf expression and SRF signaling in developing blood vessels.

SWI/SNF chromatin-remodeling enzymes Brahma-related gene 1 (BRG1) and Brahma (BRM) are dispensable in multiple models of postnatal angiogenesis but are required for vascular integrity in infant mice

Background

Mammalian SWItch/Sucrose NonFermentable (SWI/SNF) adenosine triphosphate (ATP)‐dependent chromatin‐remodeling complexes play important roles in embryonic vascular development by modulating transcription of specific target genes. We sought to determine whether SWI/SNF complexes likewise impact postnatal physiological and pathological angiogenesis.

Methods and Results

Brahma‐related gene 1 (BRG1) and Brahma gene (BRM) are ATPases within mammalian SWI/SNF complexes and are essential for the complexes to function. Using mice with vascular‐specific mutations in Brg1 or with a global mutation in Brm, we employed 3 models to test the role of these ATPases in postnatal angiogenesis. We analyzed neonatal retinal angiogenesis, exercise‐induced angiogenesis in adult quadriceps muscles, and tumor angiogenesis in control and mutant animals. We found no evidence of defective angiogenesis in Brg1 or Brm mutants using these 3 models. Brg1/Brm double mutants likewise show no evidence of vascular defects in the neonatal retina or tumor angiogenesis models. However, 100% of Brg1/Brm‐double mutants in which Brg1 deletion is induced at postnatal day 3 (P3) die by P19 with hemorrhaging in the small intestine and heart.

Conclusions

Despite their important roles in embryonic vascular development, SWI/SNF chromatin‐remodeling complexes display a surprising lack of participation in the 3 models of postnatal angiogenesis we analyzed. However, these complexes are essential for maintaining vascular integrity in specific tissue beds before weaning. These findings highlight the temporal and spatial specificity of SWI/SNF activities in the vasculature and may indicate that other chromatin‐remodeling complexes play redundant or more essential roles during physiological and pathological postnatal vascular development.

Molecular characterization, ecology, and epidemiology of a novel Tymovirus in Asclepias viridis from Oklahoma

Native virus-plant interactions require more understanding and their study will provide a basis from which to identify potential sources of emerging destructive viruses in crops. A novel tymovirus sequence was detected in Asclepias viridis (green milkweed), a perennial growing in a natural setting in the Tallgrass Prairie Preserve (TGPP) of Oklahoma. It was abundant within and frequent among A. viridis plants and, to varying extents, within other dicotyledonous and one grass (Panicum virgatum) species obtained from the TGPP. Extracts from A. viridis containing the sequence were infectious to a limited number of species. The virus genome was cloned and determined to be closely related to Kennedya yellow mosaic virus. The persistence of the virus within the Oklahoma A. viridis population was monitored for five successive years. Virus was present in a high percentage of plants within representative areas of the TGPP in all years and was spreading to additional plants. Virus was present in regions adjacent to the TGPP but not in plants sampled from central and south-central Oklahoma. Virus was present in the underground caudex of the plant during the winter, suggesting overwintering in this tissue. The RNA sequence encoding the virus coat protein varied considerably between individual plants (≈3%), likely due to drift rather than selection. An infectious clone was constructed and the virus was named Asclepias asymptomatic virus (AsAV) due to the absence of obvious symptoms on A. viridis.

Evidence for novel viruses by analysis of nucleic acids in virus-like particle fractions from Ambrosia psilostachya

To test the hypothesis that many viruses remain to be discovered in plants, a procedure was developed to sequence nucleic acids cloned randomly from virus-like particle fractions of plant homogenates. As a test of the efficiency of the procedure we targeted Ambrosia psilostachya, western ragweed, plants growing at the Tallgrass Prairie Preserve of northeastern Oklahoma. Amplifiable nucleic acid was found in the fractions from six of twelve specimens and sequences were characterized from four of them. Evidence was obtained for the presence of viruses belonging to two families (Caulimoviridae, Flexiviridae). Multiple viral species were found in two of the four specimens and their level within the isolated nucleic acid population varied from less than 1-37%. None of the sequences were derived from reported sequences of known viruses. Thus, the analysis of nucleic acid from virus-like particles is a useful tool to expand our knowledge of the universe of viruses to non-cultivated species.