Tachykinin NK1 receptor antagonist L-733,060 and substance P deletion exert neuroprotection through inhibiting oxidative stress and cell death after traumatic brain injury in mice

Role of substance P in cerebral edema and association with an estimated specific gravity of the brain and an outcome prediction in post-traumatic cerebral edema

Purpose

The study aims to evaluate the role of substance P in cerebral edema and outcomes associated with acute TBI.

Method

Patients with acute TBI who presented within 6 h and a CT scan showed predominantly cerebral edema were included in the study. Substance P level was assessed from a serum sample collected within 6 h of trauma. We also evaluated the brain-specific gravity using the Brain View software.

Result

A total of 160 (128 male) patients were recruited. The median serum substance P concentration was 167.89 (IQR: 101.09-238.2). Substance P concentration was high in the early hours after trauma (p = 0.001). The median specific gravity of the entire brain was 1.04. Patients with a low Glasgow coma scale (GCS) at admission had a high concentration of the substance P. In the univariate analysis, low GCS, elevated serum concentrations of substance P level, high Rotterdam grade, high cerebral edema grade, a high international normalized ratio value, and high blood sugar levels were associated with poor outcomes at six months. In logistic regression analysis, low GCS at admission, high cerebral edema grade, and elevated blood sugar level were strongly associated with poor outcomes at six months. The area under the receiver operating characteristic curve was 0.884 (0.826-0.941).

Conclusion

Serum substance P is strongly associated with the severity of cerebral edema after TBI. However, brain-specific gravity does not directly correlate with posttraumatic cerebral edema severity. Serum substance P does not influence the clinical outcome of traumatic brain injury.

The effect of SP/NK1R on expression and activity of glutaredoxin and thioredoxin proteins in prostate cancer cells

Substance P (SP), an important neuropeptide, has a crucial role in the progression of several cancers, including prostate cancer, through interacting with the neurokinin-1 receptor (NK1R). Oxidative stress is also involved in the onset and progression of prostate cancer. However, no studies have been performed on the cross-talk between the SP/NK1R system and cellular redox balance in prostate cancer, and how it is involved in tumorogenesis. We aimed to investigate the effect of the SP/NK1R system and the blockage of NK1R with its specific antagonist (aprepitant) on the cellular redox status of the prostate cancer cell line (PC3 and LNCaP). We performed the resazurin assay to evaluate the toxicity of the aprepitant on the PC3 and LNCaP cell lines. The intracellular reactive oxygen species (ROS) level was measured after SP and aprepitant treatment. The alterations of expression and activity of two crucial cellular oxidoreductases, glutaredoxin, and thioredoxin were evaluated by qRT-PCR and commercial kits (ZellBio GmbH), respectively. Our results revealed that SP increased ROS production and decreased the expression and activity of glutaredoxin and thioredoxin. On the other hand, treatment of cells with aprepitant showed reverse results. In conclusion, we found that the SP/NK1R system could promote prostate cancer progression by inducing oxidative stress. In addition, the inhibition of NK1R by aprepitant modulated the effect of the SP/NK1R system on the cellular redox system. Aprepitant might therefore be introduced as a candidate for the treatment of prostate cancer; however, more studies are required to confirm the validation of this hypothesis.

The Role of Substance P Within Traumatic Brain Injury and Implications for Therapy

This review examines the role of the neuropeptide substance P within the neuroinflammation that follows traumatic brain injury. It examines it in reference to its preferential receptor, the neurokinin-1 receptor, and explores the evidence for antagonism of this receptor in traumatic brain injury with therapeutic intent. Expression of substance P increases following traumatic brain injury. Subsequent binding to the neurokinin-1 receptor results in neurogenic inflammation, a cause of deleterious secondary effects that include an increased intracranial pressure and poor clinical outcome. In several animal models of TBI, neurokinin-1 receptor antagonism has been shown to reduce brain edema and the resultant rise in intracranial pressure. A brief overview of the history of substance P is presented, alongside an exploration into the chemistry of the neuropeptide with a relevance to its functions within the central nervous system. This review summarizes the scientific and clinical rationale for substance P antagonism as a promising therapy for human TBI.

Chronic pruritus: from pathophysiology to drug design

Pruritus, the most common symptom in dermatology, is an innate response capable of protecting skin against irritants. Nonetheless, when it lasts more than six weeks it is assumed to be a chronic pathology having a negative impact on people's lives. Chronic pruritus (CP) can occur in common and rare skin diseases, having a high prevalence in global population. The existing therapies are unable to counteract CP or are associated with adverse effects, so the development of effective treatments is a pressing issue. The pathophysiological mechanisms underlying CP are not yet completely dissected but, based on current knowledge, involve a wide range of receptors, namely neurokinin 1 receptor (NK1R), Janus kinase (JAK), and transient receptor potential (TRP) ion channels, especially transient receptor potential vanilloid 1 (TRPV1) and transient receptor potential ankyrin 1 (TRPA1). This review will address the relevance of these molecular targets for the treatment of CP and molecules capable of modulating these receptors that have already been studied clinically or have the potential to possibly alleviate this pathology. According to scientific and clinical literature, there is an increase in the expression of these molecular targets in the lesioned skin of patients experiencing CP when compared with non-lesioned skin, highlighting their importance for the development of potential efficacious drugs through the design of antagonists/inhibitors.

TrkB agonist N-acetyl serotonin promotes functional recovery after traumatic brain injury by suppressing ferroptosis via the PI3K/Akt/Nrf2/Ferritin H pathway

Ferroptosis is a form of regulated cell death that is mainly triggered by iron-dependent lipid peroxidation. A growing body of evidence suggests that ferroptosis is involved in the pathophysiology of traumatic brain injury (TBI), and tropomyosin-related kinase B (TrkB) deficiency would mediate TBI pathologies. As an agonist of TrkB and an immediate precursor of melatonin, N-acetyl serotonin (NAS) exerts several beneficial effects on TBI, but there is no information regarding the role of NAS in ferroptosis after TBI. Here, we examined the effect of NAS treatment on TBI-induced functional outcomes and ferroptosis. Remarkably, the administration of NAS alleviated TBI-induced neurobehavioral deficits, lesion volume, and neurodegeneration. NAS also rescued TBI-induced mitochondrial shrinkage, the changes in ferroptosis-related molecule expression, and iron accumulation in the ipsilateral cortex. Similar results were obtained with a well-established ferroptosis inhibitor, liproxstatin-1. Furthermore, NAS activated the TrkB/PI3K/Akt/Nrf2 pathway in the mouse model of TBI, while inhibition of PI3K and Nrf2 weakened the protection of NAS against ferroptosis both in vitro and in vivo, suggesting that a possible pathway linking NAS to the action of anti-ferroptosis was TrkB/PI3K/Akt/Nrf2. Given that ferritin H (Fth) is a known transcription target of Nrf2, we then investigated the effects of NAS on neuron-specific Fth knockout (Fth-KO) mice. Strikingly, Fth deletion almost abolished the protective effects of NAS against TBI-induced ferroptosis and synaptic damage, although Fth deletion-induced susceptibility toward ferroptosis after TBI was reversed by an iron chelator, deferoxamine. Taken together, these data indicate that the TrkB agonist NAS treatment appears to improve brain function after TBI by suppressing ferroptosis, at least in part, through activation of the PI3K/Akt/Nrf2/Fth pathway, providing evidence that NAS is likely to be a promising anti-ferroptosis agent for further treatment for TBI.

Changes in the Enteric Neurons Containing Selected Active Substances in the Porcine Descending Colon after the Administration of Bisphenol A (BPA)

Bisphenol A (BPA) is an endocrine disruptor widely distributed in the environment due to its common use in the plastics industry. It is known that it has a strong negative effect on human and animal organisms, but a lot of aspects of this impact are still unexplored. This includes the impact of BPA on the enteric nervous system (ENS) in the large intestine. Therefore, the aim of the study was to investigate the influence of various doses of BPA on the neurons located in the descending colon of the domestic pig, which due to similarities in the organization of intestinal innervation to the human gastrointestinal tract is a good animal model to study processes occurring in human ENS. During this study, the double immunofluorescence technique was used. The obtained results have shown that BPA clearly affects the neurochemical characterization of the enteric neurons located in the descending colon. The administration of BPA caused an increase in the number of enteric neurons containing substance P (SP) and vasoactive intestinal polypeptide (VIP) with a simultaneously decrease in the number of neurons positive for galanin (GAL) and vesicular acetylcholine transporter (VAChT used as a marker of cholinergic neurons). Changes were noted in all types of the enteric plexuses, i.e., the myenteric plexus, outer submucous plexus and inner submucous plexus. The intensity of changes depended on the dose of BPA and the type of enteric plexus studied. The results have shown that BPA may affect the descending colon through the changes in neurochemical characterization of the enteric neurons located in this segment of the gastrointestinal tract.

Immune modulation after traumatic brain injury

Traumatic brain injury (TBI) induces instant activation of innate immunity in brain tissue, followed by a systematization of the inflammatory response. The subsequent response, evolved to limit an overwhelming systemic inflammatory response and to induce healing, involves the autonomic nervous system, hormonal systems, and the regulation of immune cells. This physiological response induces an immunosuppression and tolerance state that promotes to the occurrence of secondary infections. This review describes the immunological consequences of TBI and highlights potential novel therapeutic approaches using immune modulation to restore homeostasis between the nervous system and innate immunity.

Aprepitant attenuates NLRC4-dependent neuronal pyroptosis via NK1R/PKCδ pathway in a mouse model of intracerebral hemorrhage

BACKGROUND

Pyroptosis is a programmed cell death mediated by inflammasomes. Previous studies have reported that inhibition of neurokinin receptor 1 (NK1R) exerted neuroprotection in several neurological diseases. Herein, we have investigated the role of NK1R receptor inhibition using Aprepitant to attenuate NLRC4-dependent neuronal pyroptosis after intracerebral hemorrhage (ICH), as well as the underlying mechanism.

METHODS

A total of 182 CD-1 mice were used. ICH was induced by injection of autologous blood into the right basal ganglia. Aprepitant, a selective antagonist of NK1R, was injected intraperitoneally at 1 h after ICH. To explore the underlying mechanism, NK1R agonist, GR73632, and protein kinase C delta (PKCδ) agonist, phorbol 12-myristate 13-acetate (PMA), were injected intracerebroventricularly at 1 h after ICH induction, and small interfering ribonucleic acid (siRNA) for NLRC4 was administered via intracerebroventricular injection at 48 h before ICH induction, respectively. Neurobehavioral tests, western blot, and immunofluorescence staining were performed.

RESULTS

The expression of endogenous NK1R and NLRC 4 were gradually increased after ICH. NK1R was expressed on neurons. Aprepitant significantly improved the short- and long-term neurobehavioral deficits after ICH, which was accompanied with decreased neuronal pyroptosis, as well as decreased expression of NLRC4, Cleaved-caspase-1, GSDMD (gasdermin D), IL-1β, and IL-18. Activation of NK1R or PKCδ abolished these neuroprotective effects of Aprepitant after ICH. Similarly, knocking down NLRC4 using siRNA produced similar neuroprotective effects.

CONCLUSION

Aprepitant suppressed NLRC4-dependent neuronal pyroptosis and improved neurological function, possibly mediated by inhibition of NK1R/PKCδ signaling pathways after ICH. The NK1R may be a promising therapeutic target for the treatment of ICH.

Substance P promotes the progression of bronchial asthma through activating the PI3K/AKT/NF-κB pathway mediated cellular inflammation and pyroptotic cell death in bronchial epithelial cells

NOD-like receptor family pyrin domain containing three (NLRP3) inflammasome-mediated pyroptotic cell death and inflammation contribute to the pathogenesis of bronchial asthma, and it is reported that Substance P (SP) plays important role in the process, however, the detailed molecular mechanisms by which SP participates in the aggravation of bronchial asthma have not been fully studied. Here, our clinical data showed that SP and its receptor Neurokinin-1 receptor (NK1R) were significantly elevated in the plasma and peripheral blood mononuclear cell (PBMC) collected from patients with bronchial asthma, and further pre-clinical experiments evidenced that SP suppressed cell viability, accelerated lactate dehydrogenase (LDH) release, and upregulated ASC, Caspase-1, NLRP3, IL-1β and IL-18 to promote pyroptotic cell death and cellular inflammation in the human bronchial epithelial cells and asthmatic mice models in vitro and in vivo. Interestingly, SP-induced pyroptotic cell death was reversed by NK1R inhibitor L732138. Then, we uncovered the underlying mechanisms, and found that SP activated the downstream PI3K/AKT/NF-κB signal pathway in a NK1R-dependent manner, and blockage of this pathway by both PI3K inhibitor (LY294002) and NF-κB inhibitor (MG132) reversed SP-induced pyroptotic cell death and recovered cell viability in bronchial epithelial cells. Collectively, we concluded that SP interacted with its receptor NK1R to activate the PI3K/AKT/NF-κB pathway, which further triggered NLRP3-mediated pyroptotic cell death in the bronchial epithelial cells, resulting in the aggravation of bronchial asthma.

The redox modulatory effects of SP/NK1R system: Implications for oxidative stress-associated disorders

Oxidative stress which refers to redox imbalance with increased generation of reactive oxygen species (ROS) has been associated with the pathophysiology of diverse disease conditions. Recently, a close, yet not fully understood, relation between oxidative stress and neuropeptides, in particular, substance P (SP), has been reported in certain conditions. SP has been shown to affect the cellular redox environment through activation of neurokinin-1receptor (NK1R). It seems that SP/NK1R system and oxidative stress can act either synergistically or antagonistically in a context-dependent manner, thereby, influencing the pathology of various clinical disorders either destructively or protectively. Importantly, the interactions between oxidative stress and SP/NK1R system can be pharmacologically targeted. Therefore, a better understanding of the redox modulatory properties of SP/NK1R signaling will pave the way for identifying new therapeutic possibilities for attenuating oxidative stress-mediated damage. Towards this end, we performed a comprehensive search through PubMed/Medline and Scopus databases and discussed all related existing literature regarding the interplay between oxidative stress and SP/NK1R system as well as their implication in various clinical disorders, to provide a clear view and hence better management of oxidative damage.

The SP/NK1R System-Mediated ROS Generation in GBM Cells through Inhibiting Glutaredoxin Protein

Altered redox balance is among the main contributing factors developing glioblastoma multiforme (GBM), a highly aggressive grade IV brain tumor. Neuropeptide substance P (SP) plays a key role in modifying the cellular redox environment by activating the neurokinin-1 receptor (NK1R). In this study, we aimed to investigate the redox-modulating properties of both SP and a commercially available NK1R antagonist, aprepitant in GBM cells. To detect the effect of aprepitant on the viability of U87 glioblastoma cells, resazurin assay was applied. The level of intracellular ROS was assessed using 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA) assay. The expression of glutaredoxin, a well-known redox-active protein, was measured by quantitative real-time polymerase chain reaction (qRT-PCR). Concurrently, the activity of glutaredoxin was also analyzed by a commercial kit (ZellBio GmbH). We found that SP increased the intracellular levels of reactive oxygen species (ROS) in U87 GBM cells, and aprepitant remarkably decreased this effect. We also explored the effects of SP/NK1R signaling on the glutaredoxin system as a major cellular redox buffer in GBM cells. SP reduced both expression and enzymatic activity of glutaredoxin, and these effects were significantly decreased by aprepitant. In conclusion, our results suggest a possible involvement of SP/NK1R signaling in GBM pathogenesis through oxidative stress and offering new insight for the application of aprepitant as a redox-modulating strategy in GBM patients.

Microenvironmental Variations After Blood-Brain Barrier Breakdown in Traumatic Brain Injury

Traumatic brain injury (TBI) is linked to several pathologies. The blood-brain barrier (BBB) breakdown is considered to be one of the initial changes. Further, the microenvironmental alteration following TBI-induced BBB breakdown can be multi-scaled, constant, and dramatic. The microenvironmental variations after disruption of BBB includes several pathological changes, such as cerebral blood flow (CBF) alteration, brain edema, cerebral metabolism imbalances, and accumulation of inflammatory molecules. The modulation of the microenvironment presents attractive targets for TBI recovery, such as reducing toxic substances, inhibiting inflammation, and promoting neurogenesis. Herein, we briefly review the pathological alterations of the microenvironmental changes following BBB breakdown and outline potential interventions for TBI recovery based on microenvironmental modulation.

Genetic Modulators of Traumatic Brain Injury in Animal Models and the Impact of Sex-Dependent Effects

Traumatic brain injury (TBI) is a major health problem causing disability and death worldwide. There is no effective treatment, due in part to the complexity of the injury pathology and factors affecting its outcome. The extent of brain injury depends on the type of insult, age, sex, lifestyle, genetic risk factors, socioeconomic status, other co-injuries, and underlying health problems. This review discusses the genes that have been directly tested in TBI models, and whether their effects are known to be sex-dependent. Sex differences can affect the incidence, symptom onset, pathology, and clinical outcomes following injury. Adult males are more susceptible at the acute phase and females show greater injury in the chronic phase. TBI is not restricted to a single sex; despite variations in the degree of symptom onset and severity, it is important to consider both female and male animals in TBI pre-clinical research studies.

Neurokinin Receptor 1 (NK1R) Antagonist Aprepitant Enhances Hematoma Clearance by Regulating Microglial Polarization via PKC/p38MAPK/NFκB Pathway After Experimental Intracerebral Hemorrhage in Mice

Hematoma clearance is an important therapeutic target to improve outcome following intracerebral hemorrhage (ICH). Recent studies showed that Neurokinin receptor-1 (NK1R) inhibition exerts protective effects in various neurological disease models, but its role in ICH has not been explored. The objective of this study was to investigate the role of NK1R and its relation to hematoma clearance after ICH using an autologous blood injection mouse model. A total of 332 adult male CD1 mice were used. We found that the expression levels of NK1R and its endogenous ligand, substance P (SP), were significantly upregulated after ICH. Intraperitoneal administration of the NK1R selective antagonist, Aprepitant, significantly improved neurobehavior, reduced hematoma volume and hemoglobin levels after ICH, and promoted microglia polarization towards M2 phenotype. Aprepitant decreased phosphorylated PKC, p38MAPK, and NFκB p65, and downregulated M1 markers while upregulating M2 markers after ICH. Intracerebroventricular administration of the NK1R agonist, GR73632 or PKC agonist, phorbol 12-myristate 13-acetate (PMA) reversed the effects of Aprepitant. To demonstrate the upstream mediator of NK1R activation, we performed thrombin injection and found that it increased SP. Inhibiting thrombin suppressed SP and decreased M1 markers while increasing M2 microglia polarization. Thus, NK1R inhibition promoted hematoma clearance after ICH by increasing M2 microglial polarization via downregulating PKC/p38MAPK/NFκB signaling pathway, and thrombin may be a key upstream mediator of NK1R activation. Therapeutic interventions inhibiting NK1R signaling may be a new target for the treatment of ICH.

Biomarkers and Their Possible Functions in the Intestinal Microenvironment of Chagasic Megacolon: An Overview of the (Neuro)inflammatory Process

The association between inflammatory processes and intestinal neuronal destruction during the progression of Chagasic megacolon is well established. However, many other components play essential roles, both in the long-term progression and control of the clinical status of patients infected with Trypanosoma cruzi. Components such as neuronal subpopulations, enteric glial cells, mast cells and their proteases, and homeostasis-related proteins from several organic systems (serotonin and galectins) are differentially involved in the progression of Chagasic megacolon. This review is aimed at revealing the characteristics of the intestinal microenvironment found in Chagasic megacolon by using different types of already used biomarkers. Information regarding these components may provide new therapeutic alternatives and improve the understanding of the association between T. cruzi infection and immune, endocrine, and neurological system changes.

Pathogenic role of the SP/ NK1R system in GBM cells through inhibiting the thioredoxin system

OBJECTIVES

Glioblastoma multiforme (GBM), a highly aggressive Grade IV brain tumor, is a significant public health issue due to its poor prognosis and incurability. Neuropeptide substance P (SP) plays a critical role in GBM tumor growth and development via activation of neurokinin-1receptor (NK1R). Moreover, SP is a pro-oxidant factor contributing to oxidative stress in various cell types. However, the link between SP and oxidative stress in cancer cells is not fully investigated. Here, we aimed to identify the effects of SP and NK1R antagonist, aprepitant, on the redox status of GBM cells.

MATERIALS AND METHODS

Resazurin assay was employed to determine the effect of aprepitant on viability of U87 glioblastoma cells. 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) assay was employed to measure the levels of intracellular reactive oxygen species (ROS). A quantitative real-time polymerase chain reaction was applied to measure the expression of proteins of the thioredoxin system. Commercial kits (ZellBio GmbH) were also used to measure the enzymatic activity of these proteins.

RESULTS

We found that SP increased ROS level in U87 GBM cells, and aprepitant significantly reduced this effect. Furthermore, we found that SP could also affect the thioredoxin system, a central antioxidant enzyme defense system. SP reduced both expression and enzymatic activity of the thioredoxin system's proteins, Trx and thioredoxin reductase (TrxR) and these effects were significantly reduced by aprepitant.

CONCLUSION

Our results indicated that SP activation of NK1R represented a link between oxidative stress and GBM and highlighted the need for further validations in future studies.

Mdivi-1 alleviates brain damage and synaptic dysfunction after intracerebral hemorrhage in mice

As a selective inhibitor of mitochondrial fission protein dynamin-related protein-1 (Drp1), mitochondrial division inhibitor 1 (mdivi-1) can cross the blood-brain barrier (BBB) and exert neuroprotection. However, it remains unclear whether mdivi-1 can attenuate intracerebral hemorrhage (ICH)-induced secondary brain injury. This study was undertaken to characterize the roles of mdivi-1 in short-term and long-term behavioral outcomes, along with synaptic plasticity changes in mice after ICH. The results indicated mdivi-1 reversed Drp1 translocation and the morphologic changes of mitochondria, as well as ameliorated short-term neurobehavioral deficits, the BBB disruption and brain edema remarkably. In addition, mdivi-1 could rescue ICH-induced motor and memory dysfunctions. Mdivi-1 could also prevent ICH-induced reductions in synaptic proteins (synapsin I, PSD95) and phosphorylated cAMP-response element binding (p-CREB). In vitro, mdivi-1 inhibited hemin-induced hippocampal neuron death and improved neurite outgrowth. In conclusion, we found that mdivi-1 can alleviate short-term and long-term neurological deficits, synaptic dysfunction. These findings demonstrate that mdivi-1 may be beneficial in the treatment of secondary brain injury, synaptic dysfunction and neurological outcomes caused by ICH.

Inhibition of angiotensin converting enzyme induces mechanical allodynia through increasing substance P expression in mice

Although emerging evidence shows that angiotensin converting enzyme (ACE) is associated with pain, it is not clear whether inhibition of ACE could affect to nociceptive transmission and which mediators are involved in this process. Here we investigated whether administration of the ACE inhibitors, captopril and enalapril increases the expression of substance P (SP) and whether this increase contributes to the induction of mechanical allodynia in mice. ACE was expressed in the lumbar dorsal root ganglion (DRG) and the superficial dorsal horn (SDH) region of the spinal cord in mice. Either intraperitoneal or intrathecal administration of the ACE inhibitors, captopril and enalapril for 10 days significantly increased the paw withdrawal frequency to innocuous mechanical stimuli and the levels of SP in both the lumbar DRG and the SDH region of the spinal cord dorsal horn. In addition, intraperitoneal administration of the SP receptor (neurokinin-1 receptor) antagonist, L-733,060 suppressed mechanical allodynia that was induced by pretreatment of captopril and enalapril. Intraplantar administration of SP for 3 days induces mechanical allodynia, and this effect was reduced by exogenous ACE administration. These findings demonstrate that inhibition of ACE increases the levels of SP in both the lumbar DRG and spinal cord dorsal horn, ultimately contributing to the induction of mechanical allodynia in mice.

Neuroprotective effect of hydrogen sulfide against glutamate-induced oxidative stress is mediated via the p53/glutaminase 2 pathway after traumatic brain injury

Several reports suggest that hydrogen sulfide (H₂S) exerts multiple biological and physiological effects on the pathogenesis of traumatic brain injury (TBI). However, the exact molecular mechanism involved in this effect is not yet fully known. In this study, we found that H₂S alleviated TBI-induced motor and spatial memory deficits, brain pathology, and brain edema. Moreover, sodium hydrosulfide (NaHS), an H₂S donor, treatment markedly increased the expression of Bcl-2, while inhibited the expression of Bax and Cleaved caspase-3 in TBI-challenged rats. Tunnel staining also demonstrated these results. Treatment with NaHS significantly reduced the glutamate and glutaminase 2 (GLS-2) protein levels, and glutamate-mediated oxidative stress in TBI-challenged rats. Furthermore, we demonstrated that H₂S treatment inhibited glutamate-mediated oxidative stress through the p53/GLS-2 pathway. Therefore, our results suggested that H₂S protects brain injury induced by TBI through modulation of the glutamate-mediated oxidative stress in the p53/GLS-2 pathway-dependent manner.

Effects of in vitro exposure of perfluorooctanoic acid and monocrotophos on astroglia SVG p12 cells

Glia cells provide supportive functions to the central nervous system and can be compromised by environmental contaminants. The primary objective of this study was to characterize the effects of in vitro exposure to perfluorooctanoic acid, a persistent environmental contaminant and/or monocrotophos (MCP), a neurotoxic organophosphate that is rapidly metabolized, to astroglia SVG p12 cells. The endpoints evaluated include cell viability, intracellular glutamate levels as a marker of astrocyte homeostasis function, differential gene expression for selected proteins, which include inflammatory markers (tachykinin), astrocytosis (nestin), S100B, and metabolism enzymes (CYP1A1). The results from cell viability revealed significant differences from the controls at some of the concentrations tested. Also, intracellular glutamate levels were elevated at the 10-μM concentration for perfluorooctanoic acid (PFOA) as well as the 10-μM PFOA/5-μM MCP concentration. Gene expression results at 80-μM PFOA concentration revealed a significant increase in the expression of S100B, tachykinin and CYP1A1. A combination of 10-μM PFOA/20-μM MCP caused a significant decrease in the expression of tachykinin. Gene expression for MCP exposures produced a decrease at the 20-μM MCP concentration. Immunofluorescence results indicated an increase in nestin protein expression for the 20-μM concentration of MCP, which contradicted the gene expression at the same concentration tested. The results indicate that toxicity to glia cells can compromise critical glia functions and could be implicated in neurodegenerative diseases.

Serum Substance P Concentration in Children With Traumatic Brain Injury: A First Report

OBJECTIVE

To review the clinic value and severity assessment of serum substance P (SP) concentration in children with different degrees of traumatic brain injury (TBI) through analyzing correlations with outcomes.

METHODS

One hundred thirty-nine children with TBI who were diagnosed and treated at Nanjing Medical University for longer than 72 hours between June 2017 and 2019 were analyzed. Blood samples were obtained within 24 hours after TBI to measure SP concentration. The endpoint was discharge mortality. Thirty healthy children composed the control group. Comparative analyses of differences in SP concentration were conducted for the different groups. Both the Sequential Organ Failure Assessment (SOFA) scores and Pediatric Clinical Illness Score (PCIS) were measured on admission and used in univariate and multivariate analyses.

RESULTS

The serum SP (89.10 ± 64.32) pmol/L) level in the case group was significantly higher than that in the control group (21.84 ± 2.09) pmol/L (t = 5.71, P < 0.05). The serum SP (182.81 ± 58.39) pmol/L) level in the deceased group was significantly higher than that in the survival group (59.93 ± 27.90) pmol/L (t = 16.52, P < 0.05). A negative correlation existed between serum SP concentration and Glasgow Coma Scale score in the severe, moderate, and mild groups (r = -0.72, P < 0.05). Serum SP concentration was identified as an independent risk factor for mortality (odds ratio >1, 95% confidence interval = 1.04-1.28, P < 0.01). Receiver operating characteristic curve analysis suggested that serum SP concentration had the same calibrating power as SOFA and PCIS in discriminating the risk of death of children.

CONCLUSIONS

Serum SP concentration was associated with severity in children with TBI, and extremely high levels indicated a poor prognosis.

Ferroptosis-relevant mechanisms and biomarkers for therapeutic interventions in traumatic brain injury

Traumatic brain injury (TBI) is one of the most significant health care problems worldwide, causing disability and death especially among young individuals. Although a large range of agents and therapies have been proved beneficial to lesions post-TBI to some extent, effective treatments have not been translated to the clinic. As a newly discovered form of iron-dependent regulated cell death, ferroptosis has been implicated in TBI. In this review, we update the current state of knowledge related to second injuries post-TBI, including ferroptosis, oxidative stress, mitochondrial dysfunction, neuroinflammation and so on, which often lead to chronic symptoms and long-term disability. This review systematically summarizes the latest progress in the pathophysiological mechanisms of TBI, with a focus on providing references for proposing new multi-molecular targets for comprehensive therapeutic strategies based on ferroptosis-relevant mechanisms. In addition, biomarkers are essential diagnostic and prognostic tools in TBI. Several biomarkers associated with the outcome of TBI have been listed in this article, such as Pde10a, MDA, UCH-L1, S100A9, S100B, ALDOC, ACSL4, MBP and F2-Isoprostane. Therefore, the understating of ferroptosis-relevant mechanisms and biomarkers may contribute to development of promising therapies for TBI clinical trials.

Serum substance P levels and early mortality of spontaneous intracerebral haemorrhage patients

INTRODUCTION AND GOAL

Substance P, a neuropeptide of the tachykinin family, is involved in the neuroinflammation of different diseases of the central nervous system. To our knowledge, there is no published data on the level of circulating substance P levels in the prognosis of patients with spontaneous intracerebral hemorrhage (ICH). Therefore, the objectives of this observational and prospective study were to determine whether serum substance P levels in ICH patients were associated with early mortality and whether could be used in the mortality prognostic.

MATERIAL AND METHODS

We included patients with severe primary supratentorial ICH (defined as Glasgow Coma Scale < 9) from 6 Intensive Care Units of Spanish hospitals. We determined serum substance P levels at the time of severe ICH diagnosis, at fourth and at eighth day. Thirty-day mortality was considered the end-point study.

FINDINGS

Non-surviving (n=53) compared to surviving ICH patients (n=64) showed higher serum substance P levels at day 1 (p<0.001), day 4 (p<0.001) and day 8 (p<0.001). The area under the curve for 30-day mortality prediction by serum substance P levels was of 79% (95% CI = 70-86%; p<0.001). Kaplan-Meier analysis showed a higher 30-day mortality in patients with serum substance P levels>503 pg/mL (Hazard ratio=14.7; 95% CI=6.88-31.55; p<0.001). Multiple logistic regression analysis showed an association between serum substance P levels and 30-day mortality (Odds Ratio=1.006; 95% CI=1.002-1.010; p=0.004) controlling for ICH score, midline shift, glycemia, early evacuation of ICH.

CONCLUSIONS

Thus, the novel aspects our study include that serum substance P levels in severe primary ICH patients were higher in non-surviving than in surviving patients, that serum substance P levels were associated with early mortality controlling for other variables, and that serum substance P levels could be used as biomarkers of prognosis.

Evaluation of serum level of substance P and tissue distribution of NK-1 receptor in colorectal cancer

Colorectal cancer (CRC) is known as the most common form of malignancies in the world and its occurrence is annually increasing. Due to the relatively high death rates in patients, finding better diagnostic and prognostic factors are required. Substance P (SP) belongs to the tachykinin family that acts as an immunomodulator by binding to the neurokinin-1 receptor (NK1R). The interaction of SP with NK1R might be involved in tumor cell proliferation, angiogenesis, and migration. Hence, this study was aimed to evaluate the serum SP level and tissue distribution of NK1Rs in CRC. Also, we assessed the relationship between tissue distribution of NK1R and some different tumor characteristics, including tumor size, and lymph node status. Recruiting 38 patients primarily diagnosed with CRC, the tissue distribution of NK1R was immunohistochemically evaluated in tumor tissues and their adjacent normal tissue. The serum level of SP was measured using an ELISA method in both cases and healthy control group. The SP value was significantly increased in the serum of patients in comparison with the healthy group (p = 0.001). Tumor tissues expressed a higher number of NK1R than adjacent normal tissues (p = 0.01) considering both the percentage of stained cells and intensity of staining. However, there was not any statistically significant relevance between NK1R distribution and tumor characteristics. The SP/NK1R system is involved in tumorigenesis of CRC, and might be suggested as a potent prognostic or diagnostic factor, or a new target in the treatment of CRC.

High serum substance P levels and mortality after malignant middle cerebral artery infarction

PURPOSE

Previously our team found higher serum substance P concentrations at day 1 of a malignant middle cerebral artery infarction (MMCAI) in non-surviving than in surviving patients. Thus, the objective of this study was to determine whether serum substance P levels during the first week of MMCAI could predict mortality.

METHODS

We included patients with MMCAI defined as computed tomography findings of acute infarction in at least of 50% of the territory and Glasgow Coma Scale ≤8. We determined serum concentrations of substance P on days 1, 4 and 8 of MMCAI. Thirty-day mortality was the study end-point.

RESULTS

Serum substance P concentrations at days 1 (p < .001), 4 (p < .001), and 8 (p = .001) of MMCAI in non-surviving (n = 34) were higher than in surviving patients (n = 34). Receiver operating characteristic analyses showed that serum substance P concentrations at days 1, 4, and 8 of MMCAI had an area under curve (95% confidence intervals) to predict 30-day mortality of 0.77 (0.66-0.87; p < .001), 0.82 (0.69-0.91; p < .001) and 0.85 (0.72-0.94; p < .001) respectively.

CONCLUSIONS

The two new findings of our study are that non-surviving MMCAI patients showed higher serum substance P levels at day 1, 4 and 8 than surviving, and that those levels could predict 30-day mortality.

Neuroprotective Effects of Serpina3k in Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of disability and mortality worldwide, in part resulting from secondary apoptosis of neurons in peri-contusion areas. Serpina3k, a serine protease inhibitor, has been shown to inhibit apoptosis in injury models. In this study, we investigated the anti-apoptotic function of serpina3k in vivo using a mouse model of TBI, as well as the underlying neuroprotective mechanism in vitro using the SH-SY5Y human neuroblastoma cell line. TBI was induced in adult male C57BL/6 mice using controlled cortical impact. Serpina3k protein was intravenously administered at a concentration of 0.5 mg/kg twice daily for up to 14 days. SH-SY5Y cells were subjected to biaxial stretch injury and then treated with different concentrations of serpina3k. We found that endogenous serpina3k protein levels were elevated in peri-contusion areas of the mouse brain following TBI. Serpina3k-treated mice had fewer apoptotic neurons, lower levels of oxidative stress, and showed greater recovery of neurological deficits relative to vehicle-treated mice. Meanwhile, in the SH-SY5Y cell injury model, serpina3k at an optimal concentration (150 nM) inhibited the generation of intracellular reactive oxygen species, abrogated changes of the mitochondrial membrane potential, and reduced the phospho-extracellular regulated protein kinases (p-ERK)/ERK, phospho-P38 (p-P38)/P38, B cell lymphoma (Bcl)-2-associated X protein/Bcl-2, and cleaved caspase-3/caspase-3 ratios, thereby reducing the apoptosis rate. These results demonstrate that serpina3k exerts a neuroprotective function following TBI and thus has therapeutic potential.