Neuronal degeneration and iNOS expression in experimental brain contusion following treatment with colchicine, dexamethasone, tirilazad mesylate and nimodipine

Nimodipine ameliorates liver fibrosis via reshaping liver immune microenvironment in TAA-induced in mice

Nimodipine, a calcium antagonist, exert beneficial neurovascular protective effects in clinic. Recently, Calcium channel blockers (CCBs) was reported to protect against liver fibrosis in mice, while the exact effects of Nimodipine on liver injury and hepatic fibrosis remain unclear. In this study, we assessed the effect of nimodipine in Thioacetamide (TAA)-induced liver fibrosis mouse model. Then, the collagen deposition and liver inflammation were assessed by HE straining. Also, the frequency and phenotype of NK cells, CD4+T and CD8+T cells and MDSC in liver and spleen were analyzed using flow cytometry. Furthermore, activation and apoptosis of primary Hepatic stellate cells (HSCs) and HSC line LX2 were detected using α-SMA staining and TUNEL assay, respectively. We found that nimodipine administration significantly attenuated liver inflammation and fibrosis. And the increase of the numbers of hepatic NK and NKT cells, a reversed CD4+/CD8+T ratio, and reduced the numbers of MDSC were observed after nimodipine treatment. Furthermore, nimodipine administration significantly decreased α-SMA expression in liver tissues, and increased TUNEL staining adjacent to hepatic stellate cells. Nimodipine also reduced the proliferation of LX2, and significantly promoted high level of apoptosis in vitro. Moreover, nimodipine downregulated Bcl-2 and Bcl-xl, simultaneously increased expression of JNK, p-JNK, and Caspase-3. Together, nimodipine mediated suppression of growth and fibrogenesis of HSCs may warrant its potential use in the treatment of liver fibrosis.

PEG hydrogel containing dexamethasone-conjugated hyaluronic acid reduces secondary injury and improves motor function in a rat moderate TBI model

Traumatic brain injury (TBI) leads to long-term impairments in motor and cognitive function. TBI initiates a secondary injury cascade including a neuro-inflammatory response that is detrimental to tissue repair and limits recovery. Anti-inflammatory corticosteroids such as dexamethasone can reduce the deleterious effects of secondary injury; but challenges associated with dosing, administration route, and side effects have hindered their clinical application. Previously, we developed a hydrolytically degradable hydrogel (PEG-bis-AA/HA-DXM) composed of poly (ethylene) glycol-bis-(acryloyloxy acetate) (PEG-bis-AA) and dexamethasone-conjugated hyaluronic acid (HA-DXM) for local and sustained dexamethasone delivery. In this study, we evaluated the effect of locally applied PEG-bis-AA/HA-DXM hydrogel on secondary injury and motor function recovery after moderate controlled cortical impact (CCI) TBI. Hydrogel treatment significantly improved motor function evaluated by beam walk and rotarod tests compared to untreated rats over 7 days post-injury (DPI). We also observed that the hydrogel treatment reduced lesion volume, inflammatory response, astrogliosis, apoptosis, and increased neuronal survival compared to untreated rats at 7 DPI. These results suggest that PEG-bis-AA/HA-DXM hydrogels can mitigate secondary injury and promote motor functional recovery following moderate TBI.

A Systematic Review on Traumatic Brain Injury Pathophysiology and Role of Herbal Medicines in its Management

BACKGROUND

Traumatic brain injury (TBI) is a worldwide problem. Almost about sixtynine million people sustain TBI each year all over the world. Repetitive TBI linked with increased risk of neurodegenerative disorder such as Parkinson, Alzheimer, traumatic encephalopathy. TBI is characterized by primary and secondary injury and exerts a severe impact on cognitive, behavioral, psychological and other health problem. There were various proposed mechanism to understand complex pathophysiology of TBI but still there is a need to explore more about TBI pathophysiology. There are drugs present for the treatment of TBI in the market but there is still need of more drugs to develop for better and effective treatment of TBI, because no single drug is available which reduces the further progression of this injury.

OBJECTIVE

The main aim and objective of structuring this manuscript is to design, develop and gather detailed data regarding about the pathophysiology of TBI and role of medicinal plants in its treatment.

METHOD

This study is a systematic review conducted between January 1995 to June 2021 in which a consultation of scientific articles from indexed periodicals was carried out in Science Direct, United States National Library of Medicine (Pubmed), Google Scholar, Elsvier, Springer and Bentham.

RESULTS

A total of 54 studies were analyzed, on the basis of literature survey in the research area of TBI.

CONCLUSION

Recent studies have shown the potential of medicinal plants and their chemical constituents against TBI therefore, this review targets the detailed information about the pathophysiology of TBI and role of medicinal plants in its treatment.

Natural Compounds as a Therapeutic Intervention following Traumatic Brain Injury: The Role of Phytochemicals

There has been a tremendous focus on the discovery and development of neuroprotective agents that might have clinical relevance following traumatic brain injury (TBI). This type of brain injury is very complex and is divided into two major components. The first component, a primary injury, occurs at the time of impact and is the result of the mechanical insult itself. This primary injury is thought to be irreversible and resistant to most treatments. A second component or secondary brain injury, is defined as cellular damage that is not immediately obvious after trauma, but that develops after a delay of minutes, hours, or even days. This injury appears to be amenable to treatment. Because of the complexity of the secondary injury, any type of therapeutic intervention needs to be multi-faceted and have the ability to simultaneously modulate different cellular changes. Because of diverse pharmaceutical interactions, combinations of different drugs do not work well in concert and result in adverse physiological conditions. Research has begun to investigate the possibility of using natural compounds as a therapeutic intervention following TBI. These compounds normally have very low toxicity and have reduced interactions with other pharmaceuticals. In addition, many natural compounds have the potential to target numerous different components of the secondary injury. Here, we review 33 different plant-derived natural compounds, phytochemicals, which have been investigated in experimental animal models of TBI. Some of these phytochemicals appear to have potential as possible therapeutic interventions to offset key components of the secondary injury cascade. However, not all studies have used the same scientific rigor, and one should be cautious in the interpretation of studies using naturally occurring phytochemical in TBI research.

Trigeminal Pain Molecules, Allodynia, and Photosensitivity Are Pharmacologically and Genetically Modulated in a Model of Traumatic Brain Injury

The pain-signaling molecules, nitric oxide synthase (NOS) and calcitonin gene-related peptide (CGRP), are implicated in the pathophysiology of post-traumatic headache (PTH) as they are for migraine. This study assessed the changes of inducible NOS (iNOS) and its cellular source in the trigeminal pain circuit, as well as the relationship between iNOS and CGRP after controlled cortical impact (CCI) injury in mice. The effects of a CGRP antagonist (MK8825) and sumatriptan on iNOS messenger RNA (mRNA) and protein were compared to vehicle at 2 weeks postinjury. Changes in CGRP levels in the trigeminal nucleus caudalis (TNC) in iNOS knockouts with CCI were compared to wild-type (WT) mice at 3 days and 2 weeks post injury. Trigeminal allodynia and photosensitivity were measured. MK8825 and sumatriptan increased allodynic thresholds in CCI groups compared to vehicle (p < 0.01), whereas iNOS knockouts were not different from WT. Photosensitivity was attenuated in MK8825 mice and iNOS knockouts compared to WT (p < 0.05). MK8825 and sumatriptan reduced levels of iNOS mRNA and iNOS immunoreactivity in the TNC and ganglia (p < 0.01). Differences in iNOS cellular localization were found between the trigeminal ganglia and TNC. Although the knockout of iNOS attenuated CGRP at 3 days (p < 0.05), it did not reduce CGRP at 2 weeks. CGRP immunoreactivity was found in the meningeal layers post-CCI, while negligible in controls. Findings support the importance of interactions between CGRP and iNOS in mediating allodynia, as well as the individual roles in photosensitivity. Mitigating prolonged increases in CGRP may be a promising intervention for treating acute PTH.

Treatment of traumatic brain injury with anti-inflammatory drugs

Traumatic brain injury rapidly induces inflammation. This inflammation is produced both by endogenous brain cells and circulating inflammatory cells that enter from the brain. Together they drive the inflammatory response through a wide variety of bioactive lipids, cytokines and chemokines. A large number of drugs with anti-inflammatory action have been tested in both preclinical studies and in clinical trials. These drugs either have known anti-inflammatory action or inhibit the inflammatory response through unknown mechanisms. The results of these preclinical studies and clinical trials are reviewed. Recommendations are suggested on how to improve preclinical testing of drugs to make them more relevant to evaluate for clinical trials.

Investigation of the neuroprotective impact of nimodipine on Neuro2a cells by means of a surgery-like stress model

Nimodipine is well characterized for the management of SAH (subarachnoid hemorrhage) and has been shown to promote a better outcome and less DIND (delayed ischemic neurological deficits). In rat experiments, enhanced axonal sprouting and higher survival of motoneurons was demonstrated after cutting or crushing the facial nerve by nimodipine. These results were confirmed in clinical trials following vestibular Schwannoma surgery. The mechanism of the protective competence of nimodipine is unknown. Therefore, in this study, we established an in vitro model to examine the survival of Neuro2a cells after different stress stimuli occurring during surgery with or without nimodipine. Nimodipine significantly decreased ethanol-induced cell death of cells up to approximately 9% in all tested concentrations. Heat-induced cell death was diminished by approximately 2.5% by nimodipine. Cell death induced by mechanical treatment was reduced up to 15% by nimodipine. Our findings indicate that nimodipine rescues Neuro2a cells faintly, but significantly, from ethanol-, heat- and mechanically-induced cell death to different extents in a dosage-dependent manner. This model seems suitable for further investigation of the molecular mechanisms involved in the neuroprotective signal pathways influenced by nimodipine.

Perspectives on molecular biomarkers of oxidative stress and antioxidant strategies in traumatic brain injury

Traumatic brain injury (TBI) is frequently associated with abnormal blood-brain barrier function, resulting in the release of factors that can be used as molecular biomarkers of TBI, among them GFAP, UCH-L1, S100B, and NSE. Although many experimental studies have been conducted, clinical consolidation of these biomarkers is still needed to increase the predictive power and reduce the poor outcome of TBI. Interestingly, several of these TBI biomarkers are oxidatively modified to carbonyl groups, indicating that markers of oxidative stress could be of predictive value for the selection of therapeutic strategies. Some drugs such as corticosteroids and progesterone have already been investigated in TBI neuroprotection but failed to demonstrate clinical applicability in advanced phases of the studies. Dietary antioxidants, such as curcumin, resveratrol, and sulforaphane, have been shown to attenuate TBI-induced damage in preclinical studies. These dietary antioxidants can increase antioxidant defenses via transcriptional activation of NRF2 and are also known as carbonyl scavengers, two potential mechanisms for neuroprotection. This paper reviews the relevance of redox biology in TBI, highlighting perspectives for future studies.

iNOS-mediated secondary inflammatory response differs between rat strains following experimental brain contusion

BACKGROUND

Nitric oxide is a key mediator of post-traumatic inflammation in the brain. We examined the expressions of iNOS, nNOS, and eNOS in inbred DA and PVGa rat strains where DA is susceptible to autoimmune neuroinflammation and PVGa-resistant.

METHODS

Parietal contusions using a weight drop model were produced in five rats per genotype. After 24 h, the brains were removed and analyzed using a range of immunohistochemical methods.

RESULTS

PVGa presented significantly increased iNOS expression in infiltrating inflammatory cells in the perilesional area compared to DA (p < 0.05). The amount of w3/13-positive infiltrating inflammatory cells did not differ between strains. eNOS and nNOS expression did not differ between strains. iNOS-positive cells coexpressed neuronal (NeuN), macrophage (ED-1), and leucocyte (w3/13) markers. MnSOD was significantly increased in PVGa (p < 0.05). 3-Nitrotyrosine, a measure of peroxynitrite levels, and fluoro-jade stained neuronal degeneration, did not differ between strains.

CONCLUSIONS

Two inbred rat strains with genetically determined differences in susceptibility to develop autoimmune disease displayed different levels of the inflammatory and anti-inflammatory mediators iNOS and MnSOD, indicating genetic regulation. Interestingly, the increased levels of iNOS did not lead to elevated expression of the neuronal cell-death marker fluoro-jade. The increased iNOS expression was correlated with increased expression of superoxide scavenger MnSOD. Excessive peroxynitrite formation was probably prevented by limitation of available superoxide. Subsequently, the higher expression of potentially deleterious iNOS in PVGa did not result in increased neuronal death.

In vitro models of traumatic brain injury

In vitro models of traumatic brain injury (TBI) are helping elucidate the pathobiological mechanisms responsible for dysfunction and delayed cell death after mechanical stimulation of the brain. Researchers have identified compounds that have the potential to break the chain of molecular events set in motion by traumatic injury. Ultimately, the utility of in vitro models in identifying novel therapeutics will be determined by how closely the in vitro cascades recapitulate the sequence of cellular events that play out in vivo after TBI. Herein, the major in vitro models are reviewed, and a discussion of the physical injury mechanisms and culture preparations is employed. A comparison between the efficacy of compounds tested in vitro and in vivo is presented as a critical evaluation of the fidelity of in vitro models to the complex pathobiology that is TBI. We conclude that in vitro models were greater than 88% predictive of in vivo results.

Induction of pancreatitis-associated protein (PAP) family members in neurons after traumatic brain injury

The pancreatitis-associated protein (PAP) family is a group of 16-kDa secretory proteins initially identified in the pancreas in rats with acute pancreatitis. Although induction of PAP family genes was reported in peripheral nerve injury models, the expression in the central nervous system after traumatic injury has not been examined. In the present study, we examined the expression of PAP family members (PAP-I, PAP-II, and PAP-III) in the rat brain following traumatic brain injury (TBI) induced by weight drop. There was a significant upregulation of PAP-I and PAP-III mRNA in the injured cortex beginning at 1 day after TBI. Immunohistochemical double-staining indicated that PAP-I and PAP-III staining was localized in a subpopulation of neurons in the peri-injured region. Expression of both PAP-I and PAP-III mRNA was observed following a transient increase in inflammatory cytokines, including TNF-alpha, IL-6, and IL-1beta mRNA. The results of the present study suggest that expression of PAP family members in response to traumatic and inflammatory stimuli are not restricted to the pancreas, intestine, and peripheral nervous system, and are likely a more general cellular response, including the central nervous system in the rat. Thus, PAP family members may have an anti-inflammatory role, and this may contribute to the protection of injured neurons.

Dexamethasone suppresses infiltration of RhoA+ cells into early lesions of rat traumatic brain injury

Inflammatory cell infiltration is a major part of secondary tissue damage in traumatic brain injury (TBI). RhoA is an important member of Rho GTPases and is involved in leukocyte migration. Inhibition of RhoA and its downstream target, Rho-associated coiled kinase (ROCK), has been proven to promote axon regeneration and function recovery following injury in the central nervous system (CNS). Previously, we showed that dexamethasone, an immunosuppressive corticosteroid, attenuated early expression of three molecules associated with microglia/macrophages activation following TBI in rats. Here, the effects of dexamethasone on the early expression of RhoA have been investigated in brains of TBI rats by immunohistochemistry. In brains of rats treated with TBI alone, significant RhoA+ cell accumulation was observed at 18 h post-injury and continuously increased during our observed time period. The accumulated RhoA+ cells were distributed to the areas of pannecrosis and selective neuronal loss. Most accumulated RhoA+ cells were identified as active microglia/macrophages by double-labelling. Dexamethasone (1 mg/kg body weight) was intraperitoneally injected on day 0 and 2 immediately following brain injury. Numbers of RhoA+ cells were significantly reduced on day 1 and 2 following administration of dexamethasone but returned to vehicle control level on day 4. However, dexamethasone treatment did not change the proportion of RhoA+ cells. These observations suggest that dexamethasone has only a transient effect on early leukocyte recruitment.

Early attenuation of lesional interleukin-16 up-regulation by dexamethasone and FTY720 in experimental traumatic brain injury

AIMS

Interleukin-16 (IL16) is an immunomodulatory cytokine, which induces lymphocyte migration, expression of proinflammatory IL1 beta, IL6 and tumour necrosis factor-alpha, and modulates apoptosis. IL16 expression has been observed in several central nervous system diseases and may play a role in promoting inflammatory responses. Inflammation contributes considerably to secondary injury following traumatic brain injury (TBI). The aim of this study was to investigate early IL16 expression following experimental TBI and the effects of dexamethasone and FTY720 on early expression of IL16 in TBI rats.

METHODS

Rat TBI was induced using an open-skull weight-drop model. IL16 expression was studied by immunohistochemistry. TBI rats received an intraperitoneal injection of dexamethasone (1 mg/kg in 1 ml saline), FTY720 (1 mg/kg in 1 ml saline) or saline (1 ml) on Day 0 and Day 2 immediately after surgery.

RESULTS

Significant up-regulation of IL16 was seen as early as 24 h post TBI. Double-staining experiments, together with morphological classification, revealed a multicellular origin of IL16, including activated microglia/macrophages (about 85%), astrocytes (about 8%), neurones (about 5%) and granulocytes. Following peripheral administration of dexamethasone and FTY720, attenuated numbers of IL16(+) cells were observed on Days 1 and 2 but not on Day 4 post TBI for dexamethasone and on Day 4 but not earlier for FTY720 respectively.

CONCLUSIONS

Our observations reveal that dexamethasone and FTY720 have different but complementary effects on reduction of early IL16 expression following TBI.

Dexamethasone transiently attenuates up-regulation of endostatin/collagen XVIII following traumatic brain injury

Endostatin/collagen XVIII is a specific inhibitor of endothelial proliferation and migration in vitro. It has also been shown to have anti-angiogenic activity and tumor growth inhibitory activity in vivo and in vitro. Here we studied expression of endostatin/collagen XVIII in a rat traumatic brain injury (TBI) model, focusing on the early phase. A significant up-regulation of endostatin/collagen XVIII in TBI began as early as 24 h post-TBI. Double-staining experiment revealed that the major resource of endostatin/collagen XVIII(+) cells in our TBI rat model was a subpopulation of reactivated microglia/macrophages. Our data further showed that dexamethasone attenuated up-regulation of endostatin/collagen XVIII expression at days 1 and 2, but not at day 4, post-TBI, indicating that dexamethasone might possess an early and transient influence to the angiogenesis following TBI.

Dexamethasone attenuates early expression of three molecules associated with microglia/macrophages activation following rat traumatic brain injury

Corticosteroids have been used in the treatment of human traumatic brain injury (TBI), which is a leading cause of death and disability, but their efficiency is still a matter of debate. Dexamethasone was considered to delay post-traumatic inflammation and retard neuronal degeneration, resulting in attenuation of secondary injury following experimental TBI. In a rat TBI model, we have investigated the effects of dexamethasone on expression patterns of markers of inflammatory activation of microglia/macrophages by immunohistochemistry. Endothelial-monocyte activating polypeptide II (EMAP-II), P2X4 receptor (P2X4R) and allograft-inflammatory factor-1 (AIF-1) were reported to be associated with the activation of microglia/macrophages post central nervous system (CNS) injury and may play roles in inflammatory cascades of secondary brain damage. Dexamethasone significantly suppressed the accumulation of EMAP-II(+), P2X4R(+) or AIF(+) cells at Day-1 and 2 post-brain-trauma but not on Days 4 and 6, which is in accordance with the reported short- but not long-term protective effects of dexamethasone in TBI. These findings indicate a rather rapid but transient anti-inflammatory effect of dexamethasone in TBI.

Neuroprotection by selective inhibition of inducible nitric oxide synthase after experimental brain contusion

The inflammatory response is thought to be important for secondary damage following traumatic brain injury (TBI). The inducible nitric oxide synthase (iNOS) isoform is a mediator in inflammatory reactions and may catalyze substantial synthesis of NO in the injured brain. This study was undertaken to analyze neuronal degeneration and survival, cellular apoptosis and formation of nitrotyrosine following treatment with the iNOS-inhibitor L-N-iminoethyl-lysine (L-NIL) in a model of brain contusion. A brain contusion was produced using a weight-drop device in 30 rats. The animals received treatment with L-NIL or NaCl at 15 min and 12 h after the injury and were sacrificed at 24 h or 6 days after trauma. iNOS activity was measured at 24 h post-trauma by the conversion of L-[U- ( 14 )C]arginine to L-[U-( 14 )C]citrulline and immunohistochemistry for iNOS. Peroxynitrite formation was indirectly assessed by nitrotyrosine (NT) immunohistochemistry. Neuronal degeneration and survival were assessed by Fluoro-Jade (FJ) and NeuN stainings, and cellular death by TUNEL staining. iNOS activity but not iNOS immunoreactivity was significantly reduced in animals that received L-NIL. Neuronal degeneration (FJ) and NT immunoreactivity were significantly reduced at 24 h. Neuronal survival was unchanged at 24 h but increased at 6 days in L-NIL-treated animals. Cellular apoptosis of ED-1 and NeuN positive cells was significantly reduced following L-NIL treatment at 6 days after trauma. We demonstrated neuroprotection by selective inhibition of iNOS after trauma. L-NIL appeared to protect the injured brain by limiting peroxynitrite formation. Our findings support a putative harmful role of iNOS induction early after TBI.