UCH-L1 is a Poor Serum Biomarker of Murine Traumatic Brain Injury After Polytrauma.

BACKGROUND: Several serum biomarkers have been studied to diagnose incidence and severity of traumatic brain injury (TBI), but a reliable biomarker in TBI has yet to be identified. Ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) has been proposed as a biomarker in clinical and preclinical studies, largely in the setting of isolated TBI or concussion. The aim of this study was to evaluate the performance of UCH-L1 as a serum biomarker in the setting of polytrauma and TBI. METHODS: Multiple variations of murine TBI and polytrauma models were used to evaluate serum biomarkers. The different models included TBI with and without hemorrhagic shock and resuscitation, isolated extremity vascular ligation, extremity ischemia/reperfusion, and blunt tail injury. Blood was drawn at intervals after injury, and serum levels of neuron-specific enolase, UCH-L1, creatine kinase, and syndecan-1 were evaluated by enzyme-linked immunosorbent assay. RESULTS: UCH-L1 levels were not significantly different between TBI, tail injury, and sham TBI. By contrast, neuron-specific enolase levels were increased in TBI mice compared with tail injury and sham TBI mice. UCH-L1 levels increased regardless of TBI status at 30 min and 4 h after hemorrhagic shock and resuscitation. In mice that underwent femoral artery cannulation followed by hemorrhagic shock/resuscitation, UCH-L1 levels were significantly elevated compared with shock sham mice at 4 h (3158 ± 2168 pg/mL, 4 h shock versus 0 ± 0 pg/mL, 4 h shock sham; P < 0.01) and at 24 h (3253 ± 2954 pg/mL, 24 h shock versus 324 ± 482 pg/mL, 24 h shock sham; P = 0.03). No differences were observed in UCH-L1 levels between the sham shock and the arterial ligation, vein ligation, or extremity ischemia/reperfusion groups at any time point. Similar to UCH-L1, creatine kinase was elevated only after shock compared with sham mice at 4, 24, and 72 h after injury. CONCLUSIONS: Our study demonstrates that UCH-L1 is not a specific marker for TBI but is elevated in models that induce central and peripheral nerve ischemia. Given the increase in UCH-L1 levels observed after hemorrhagic shock, we propose that UCH-L1 may be a useful adjunct in quantifying severity of shock or global ischemia rather than as a specific marker of TBI.

Effects of Early Altitude Exposure on the Open Abdomen After Laparotomy in Trauma.

INTRODUCTION: While damage control surgery and resuscitation techniques have revolutionized the care of injured service members who sustain severe traumatic hemorrhage, the physiologic and inflammatory consequences of hemostatic resuscitation and staged abdominal surgery in the face of early aeromedical evacuation (AE) have not been investigated. We hypothesized that post-injury AE with an open abdomen would have significant physiologic and inflammatory consequences compared to AE with a closed abdomen. MATERIALS AND METHODS: Evaluation of resuscitation and staged abdominal closure was performed using a murine model of hemorrhagic shock with laparotomy. Mice underwent controlled hemorrhage to a systolic blood pressure of 25 mmHg and received either no resuscitation, blood product resuscitation, or Hextend resuscitation to a systolic blood pressure of either 50 mmHg (partial resuscitation) or 80 mmHg (complete resuscitation). Laparotomies were either closed prior to AE (closed abdomens) or left open during AE (open abdomens) and subsequently closed. AE was simulated with a 1-hour exposure to a hypobaric hypoxic environment at 8,000 feet altitude. Mice were euthanized at 0, 4, or 24 hours following AE. Serum was collected and analyzed for physiologic variables and inflammatory cytokine levels. Samples of lung and small intestine were collected for tissue cytokine and myeloperoxidase analysis as indicators of intestinal inflammation. Survival curves were also performed. RESULTS: Unresuscitated mice sustained an 85% mortality rate from hemorrhage and laparotomy, limiting the assessment of the effect of simulated AE in these subgroups. Overall survival was similar among all resuscitated groups regardless of the presence of hypobaric hypoxia, type of resuscitation, or abdominal closure status. Simulated AE had no observed effects on acid/base imbalance or the inflammatory response as compared to ground level controls. All mice experienced both metabolic acidosis and an acute inflammatory response after hemorrhage and injury, represented by an initial increase in serum interleukin (IL)-6 levels. Furthermore, mice with open abdomens had an elevated inflammatory response with increased levels of serum IL-10, serum tumor necrosis factor alpha, intestinal IL-6, intestinal IL-10, and pulmonary myeloperoxidase. CONCLUSION: These results demonstrate the complex interaction of AE and temporary or definitive abdominal closure after post-injury laparotomy. Contrary to our hypothesis, we found that AE in those animals with open abdomens is relatively safe with no difference in mortality compared to those with closed abdomens. However, given the physiologic and inflammatory changes observed in animals with open abdomens, further evaluation is necessary prior to definitive recommendations regarding the safety or downstream effects of exposure to AE prior to definitive abdominal closure.

Microvesicles generated following traumatic brain injury induce platelet dysfunction via adenosine diphosphate receptor.

BACKGROUND: Traumatic brain injury (TBI) can result in an acute coagulopathy including platelet dysfunction that can contribute to ongoing intracranial hemorrhage. Previous studies have shown adenosine diphosphate (ADP)-induced platelet aggregation to be reduced after TBI. In addition, circulating microvesicles (MVs) are increased following TBI and have been shown to play a role in post-TBI coagulopathy and platelet function. We hypothesized that post-TBI MVs would affect platelet aggregation in a murine head injury model. METHODS: Moderate TBI was performed using a weight-drop method in male C57BL6 mice. Whole blood, plasma, MVs, and MV-poor plasma were isolated from blood collected 10 minutes following TBI and were mixed separately with whole blood from uninjured mice. Platelet aggregation was measured with Multiplate impedance platelet aggregometry in response to ADP. The ADP P2Y12 receptor inhibitor, R-138727, was incubated with plasma and MVs from TBI mice, and platelet inhibition was again measured. RESULTS: Whole blood taken from 10-minute post-TBI mice demonstrated diminished ADP-induced platelet aggregation compared with sham mice. When mixed with normal donor blood, post-TBI plasma and MVs induced diminished ADP-induced platelet aggregation compared with sham plasma and sham MVs. By contrast, the addition of post-TBI MV-poor plasma to normal blood did not change ADP-induced platelet aggregation. The observed dysfunction in post-TBI ADP platelet aggregation was prevented by the pretreatment of post-TBI plasma with R-138727. Treatment of post-TBI MVs with R-138727 resulted in similar findings of improved ADP-induced platelet aggregation compared with nontreated post-TBI MVs. CONCLUSION: Adenosine diphosphate-induced platelet aggregation is inhibited acutely following TBI in a murine model. This platelet inhibition is reproduced in normal blood by the introduction of post-TBI plasma and MVs. Furthermore, observed platelet dysfunction is prevented when post-TBI plasma and MVs are treated with an inhibitor of the P2Y12 ADP receptor. Clinically observed post-TBI platelet dysfunction may therefore be partially explained by the presence of the ADP P2Y12 receptor within post-TBI MVs. LEVEL OF EVIDENCE: Level III.

ADAM10 and γ-secretase regulate sensory regeneration in the avian vestibular organs.

The loss of sensory hair cells from the inner ear is a leading cause of hearing and balance disorders. The mammalian ear has a very limited ability to replace lost hair cells, but the inner ears of non-mammalian vertebrates can spontaneously regenerate hair cells after injury. Prior studies have shown that replacement hair cells are derived from epithelial supporting cells and that the differentiation of new hair cells is regulated by the Notch signaling pathway. The present study examined molecular influences on regeneration in the avian utricle, which has a particularly robust regenerative ability. Chicken utricles were placed in organotypic culture and hair cells were lesioned by application of the ototoxic antibiotic streptomycin. Cultures were then allowed to regenerate in vitro for seven days. Some specimens were treated with small molecule inhibitors of γ-secretase or ADAM10, proteases which are essential for transmission of Notch signaling. As expected, treatment with both inhibitors led to increased numbers of replacement hair cells. However, we also found that inhibition of both proteases resulted in increased regenerative proliferation. Subsequent experiments showed that inhibition of γ-secretase or ADAM10 could also trigger proliferation in undamaged utricles. To better understand these phenomena, we used RNA-Seq profiling to characterize changes in gene expression following γ-secretase inhibition. We observed expression patterns that were consistent with Notch pathway inhibition, but we also found that the utricular sensory epithelium contains numerous γ-secretase substrates that might regulate cell cycle entry and possibly supporting cell-to-hair cell conversion. Together, our data suggest multiple roles for γ-secretase and ADAM10 in vestibular hair cell regeneration.

The transcriptome of utricle hair cell regeneration in the avian inner ear.

Sensory hair cell loss is the major cause of hearing and balance disorders. Mammals are incapable of sustained hair cell regeneration, but lower vertebrates can regenerate these mechano-electrical transducers. We present the first comprehensive transcriptome (by mRNA-Seq) of hair cell regeneration in the chick utricle. We provide pathway and pattern annotations and correlate these with the phenotypic events that occur during regeneration. These patterns are surprisingly synchronous and highly punctuated. We show how these patterns are a new resource for identifying components of the hair cell transcriptome and identify 494 new putative hair-cell-specific genes and validate three of these (of three tested) by immunohistochemical staining. We describe many surprising new components and dynamic expression patterns, particularly within NOTCH signaling. For example, we show that HES7 is specifically expressed during utricle hair cell regeneration and closely parallels the expression of HES5. Likewise, the expression of ATOH1 is closely correlated with HEYL and the HLH inhibitory transcription factors ID1, ID2, and ID4. We investigate the correlation between fibroblast growth factor signaling and supporting cell proliferation and show that FGF20 inhibits supporting cell proliferation. We also present an analysis of 212 differentially expressed transcription factor genes in the regenerative time course that fall into nine distinct gene expression patterns, many of which correlate with phenotypic events during regeneration and represent attractive candidates for future analysis and manipulation of the regenerative program in sensory epithelia and other vertebrate neuroepithelia.

A cross-species analysis of microRNAs in the developing avian face.

Higher vertebrates use similar genetic tools to derive very different facial features. This diversity is believed to occur through temporal, spatial and species-specific changes in gene expression within cranial neural crest (NC) cells. These contribute to the facial skeleton and contain species-specific information that drives morphological variation. A few signaling molecules and transcription factors are known to play important roles in these processes, but little is known regarding the role of micro-RNAs (miRNAs). We have identified and compared all miRNAs expressed in cranial NC cells from three avian species (chicken, duck, and quail) before and after species-specific facial distinctions occur. We identified 170 differentially expressed miRNAs. These include thirty-five novel chicken orthologs of previously described miRNAs, and six avian-specific miRNAs. Five of these avian-specific miRNAs are conserved over 120 million years of avian evolution, from ratites to galliforms, and their predicted target mRNAs include many components of Wnt signaling. Previous work indicates that mRNA gene expression in NC cells is relatively static during stages when the beak acquires species-specific morphologies. However, miRNA expression is remarkably dynamic within this timeframe, suggesting that the timing of specific developmental transitions is altered in birds with different beak shapes. We evaluated one miRNA:mRNA target pair and found that the cell cycle regulator p27(KIP1) is a likely target of miR-222 in frontonasal NC cells, and that the timing of this interaction correlates with the onset of phenotypic variation. Our comparative genomic approach is the first comprehensive analysis of miRNAs in the developing facial primordial, and in species-specific facial development.

An RNA interference-based screen of transcription factor genes identifies pathways necessary for sensory regeneration in the avian inner ear.

Sensory hair cells of the inner ear are the mechanoelectric transducers of sound and head motion. In mammals, damage to sensory hair cells leads to hearing or balance deficits. Nonmammalian vertebrates such as birds can regenerate hair cells after injury. In a previous study, we characterized transcription factor gene expression during chicken hair cell regeneration. In those studies, a laser microbeam or ototoxic antibiotics were used to damage the sensory epithelia (SE). The current study focused on 27 genes that were upregulated in regenerating SEs compared to untreated SEs in the previous study. Those genes were knocked down by siRNA to determine their requirement for supporting cell proliferation and to measure resulting changes in the larger network of gene expression. We identified 11 genes necessary for proliferation and also identified novel interactive relationships between many of them. Defined components of the WNT, PAX, and AP1 pathways were shown to be required for supporting cell proliferation. These pathways intersect on WNT4, which is also necessary for proliferation. Among the required genes, the CCAAT enhancer binding protein, CEBPG, acts downstream of Jun Kinase and JUND in the AP1 pathway. The WNT coreceptor LRP5 acts downstream of CEBPG, as does the transcription factor BTAF1. Both of these genes are also necessary for supporting cell proliferation. This is the first large-scale screen of its type and suggests an important intersection between the AP1 pathway, the PAX pathway, and WNT signaling in the regulation of supporting cell proliferation during inner ear hair cell regeneration.

Downstream targets of GATA3 in the vestibular sensory organs of the inner ear.

Haploinsufficiency for the transcription factor GATA3 leads to hearing loss in humans. It is expressed throughout the auditory sensory epithelium (SE). In the vestibular organs, GATA3 is limited to the striola reversal zone of the utricle. Stereocilia orientation shifts 180 degrees at this region, which contains morphologically distinct type-I hair cells. The striola is conserved in all amniotes, its function is unknown, and GATA3 is the only known marker of the reversal zone. To identify downstream targets of GATA3 that might point to striolar function, we measured gene expression differences between striolar and extra-striolar SE. These were compared with profiles after GATA3 RNAi and GATA3 over-expression. We identified four genes (BMP2, FKHL18, LMO4, and MBNL2) that consistently varied with GATA3. Two of these (LMO4 and MBNL2) were shown to be direct targets of GATA3 by ChIP. Our results suggest that GATA3 impacts WNT signaling in this region of the sensory macula.

Disruption of sodium bicarbonate transporter SLC4A10 in a patient with complex partial epilepsy and mental retardation.

OBJECTIVE: To determine gene(s) disrupted in a patient with partial frontal lobe epilepsy and cognitive impairment with concomitant de novo balanced chromosomal translocation t(2;13)(q24;q31). DESIGN: Fluorescence in situ hybridization and array comparative genomic hybridization were used to map the locations of chromosomal translocation breakpoints. RESULTS: SLC4A10 (OMIM 605556), a sodium bicarbonate transporter gene with high expression in the cerebral cortex and hippocampus, was disrupted by the translocation breakpoint on chromosome 2q24. The breakpoint on chromosome 13q31 was in a 1-megabase (Mb)-gene desert. Genomewide array comparative genomic hybridization confirmed the absence of additional chromosomal abnormalities. CONCLUSION: SLC4A10 is the third SLC4 base transporter family member to be implicated in human cognition and epilepsy.

SNTG1, the gene encoding gamma1-syntrophin: a candidate gene for idiopathic scoliosis.

Idiopathic scoliosis (IS) affects approximately 2%-3% of the population and has a heritable component. The genetics of this disorder are complex. Here, we describe a family in which a pericentric inversion of chromosome 8 co-segregates with IS. We have used fluorescence in situ hybridization to identify cloned DNAs that span the breakpoints on the two arms of the chromosome. We have identified a bacterial artificial chromosome (BAC) of 150 kb that crosses the q-arm breakpoint and a BAC of 120 kb that crosses the p-arm breakpoint. The complete genomic DNA sequence of these BACs has been analyzed to identify candidate genes and to localize further the precise breakpoints. This has revealed that the p-arm break does not interrupt any known gene and occurs in a region of highly repetitive sequence elements. On the q-arm, the break occurs between exons 10 and 11 of the gamma-1 syntrophin (SNTG1) gene. Syntrophins are a group of cytoplasmic peripheral membrane proteins that associate directly with dystrophin, the Duchenne muscular dystrophy gene; gamma1-syntrophin has been shown to be a neuronal cell-specific protein. Mutational analysis of SNTG1 exons in 152 sporadic IS patients has revealed a 6-bp deletion in exon 10 of SNTG1 in one patient and a 2-bp insertion/deletion mutation occurring in a polypyrimidine tract of intronic sequence 20 bases upstream of the SNTG1 exon 5 splice site in two patients. These changes were not seen in a screen of 480 control chromosomes. Genomic DNAs from seven affected individuals within the family of a patient carrying the 6-bp deletion were typed to determine whether the alteration co-segregated with IS. The deletion was only observed in five out of these seven individuals. Thus, although genetic heterogeneity or multiple alleles cannot be ruled out, the 6-bp deletion does not consistently co-segregate with the disease in this family.

Mutations in CD2BP1 disrupt binding to PTP PEST and are responsible for PAPA syndrome, an autoinflammatory disorder.

PAPA syndrome (pyogenic sterile arthritis, pyoderma gangrenosum, and acne, OMIM #604416) and familial recurrent arthritis (FRA) are rare inherited disorders of early onset, primarily affecting skin and joint tissues. Recurring inflammatory episodes lead to accumulation of sterile, pyogenic, neutrophil-rich material within the affected joints, ultimately resulting in significant destruction. We recently localized the genes for PAPA syndrome and FRA to chromosome 15q and suggested that they are the same disorder. We have now established this by the identification of co-segregating disease-causing mutations in the CD2-binding protein 1 (CD2BP1; GenBank accession no XM 044569) gene in the two reported families with this disorder. E250Q or A230T amino acid substitutions occur within a domain highly homologous to yeast cleavage furrow-associated protein CDC15. CD2BP1 and its murine ortholog, proline-serine-threonine phosphatase interacting protein (PSTPIP1), are adaptor proteins known to interact with PEST-type protein tyrosine phosphatases (PTP). Yeast two-hybrid assays demonstrate severely reduced binding between PTP PEST and both the E250Q and A230T mutant proteins. Previous evidence supports the integral role of CD2BP1 and its interacting proteins in actin reorganization during cytoskeletal-mediated events. We hypothesize that the disease-causing mutations that we have identified compromise physiologic signaling necessary for the maintenance of proper inflammatory response. Accordingly we suggest classification of PAPA syndrome as an autoinflammatory disease. This CD2BP1-mediated biochemical pathway(s) may function in common inflammatory disorders with apparent etiological overlap, such as rheumatoid arthritis and inflammatory bowel disease.

Positional cloning strategies for idiopathic scoliosis.

AIM: Idiopathic scoliosis (IS) affects approximately 1-2% of the population and has a heritable component. It is clear that in general IS displays the features of a complex genetic disorder; however families displaying a Mendelian inheritance pattern have been described. Our aim is to identify families segregating rare, highly penetrant loci. In the case described here the disorder appears to cosegregate with a chromosomal rearrangement. METHODS AND MATERIALS: We have studied a family in which a pericentric inversion of chromosome 8 appears to cosegregate with idiopathic scoliosis in three generations. We have used fluorescent in situ hybridization (FISH) to identify cloned DNAs that span the breakpoints on the two arms of the chromosome. These clones allow the recovery of sequence information from the breakpoint region and identification of candidate genes. RESULTS: We have identified a YAC of 1190kb that spans the p arm breakpoint and from this a cosmid of 35kb that also identifies the break. We have derived DNA sequence information on this region. We have identified a BAC of 150kb that crosses the q arm breakpoint. The complete genomic DNA sequence of this BAC is being analyzed to identify candidate genes and to further localize the precise breakpoint. CONCLUSION: We have sublocalized within two small genomic regions the position of a possible locus for idiopathic scoliosis.