stab-wound-mouse-model-for-studying-hemorrhage-inflammation-traumatic

Stab-Wound Mouse Model for Studying Hemorrhage and Inflammation in Traumatic Brain Injury

Traumatic brain injury (TBI) results from physical damage, often caused by accidents or sports-related incidents. The causes of TBI are diverse, including ...

Ochanomizu University

Vitronectin (VN), one of the serum proteins, is known to be involved in the regulation of blood coagulation, fibrinolysis, and cell migration. It has been proposed that the regulation of fibrinolysis by VN promotes the blood-brain barrier (BBB) recovery from brain injuries such as traumatic injury and subarachnoid hemorrhage. The effects of VN on fibrinolysis in the injured brain remain unclear, however. We examined the effects of VN on the fibrinolytic system in the stab-wounded cerebral cortex of VN-knockout (KO) mice. First, hemorrhage and recovery from BBB breakdown in the wounded regions were assessed by serum immunoglobulin G (IgG) extravasation. The level of IgG extravasation increased 3-7 days after the stab wound (D3-7) in the cortex of VN-KO mice, compared with that in wild type mice, indicating that VN deficiency inhibited the recovery from BBB breakdown. The VN deficiency decreased fibrin fiber deposition at D1-3, suggesting that VN deficiency tilts the balance between fibrinogenesis and fibrinolysis toward fibrinolysis. Next, the effects of VN deficiency on the fibrinolytic factors were analyzed in the stab-wounded cortex. The VN deficiency impaired the activity of plasminogen activator inhibitor-1, an inhibitor of the fibrinolytic system, at D3-5. Further, VN deficiency up-regulated the mRNA and protein expression levels of tissue-type plasminogen activator, and urokinase-type plasminogen activator. These results demonstrate that VN contributes to the regulation of the fibrinolytic system and recovery from BBB breakdown in the wounded brain.

Vitronectin Regulates the Fibrinolytic System during the Repair of Cerebral Cortex in Stab-Wounded Mice.

Traumatic brain injury (TBI) is caused by physical damage to the brain and it induces blood-brain barrier (BBB) breakdown and inflammation. To diminish the sequelae of TBI, it is important to decrease haemorrhage and alleviate inflammation. In this study, we aimed to determine the effects of 2-carba-cyclic phosphatidic acid (2ccPA) on the repair mechanisms after a stab wound injury as a murine TBI model. The administration of 2ccPA suppressed serum immunoglobulin extravasation after the injury. To elucidate the effects of 2ccPA on inflammation resulting from TBI, we analysed the mRNA expression of inflammatory cytokines. We found that 2ccPA prevents a TBI-induced increase in the mRNA expression of Il-1β, Il-6, Tnf-α and Tgf-β1. In addition, 2ccPA reduces the elevation of Iba1 levels. These data suggest that 2ccPA attenuates the inflammation after a stab wound injury via the modulation of pro-inflammatory cytokines release from microglial cells. Therefore, we focused on the function of 2ccPA in microglial polarisation towards M1 or M2 phenotypes. The administration of 2ccPA decreased the number of M1 and increased the number of M2 type microglial cells, indicating that 2ccPA modulates the microglial polarisation and shifts them towards M2 phenotype. These data suggest that 2ccPA treatment suppresses the extent of BBB breakdown and inflammation after TBI.

2-carba cyclic phosphatidic acid suppresses inflammation via regulation of microglial polarisation in the stab-wounded mouse cerebral cortex.

We examined the mechanism how 2-carba-cyclic phosphatidic acid (2ccPA), a lipid mediator, regulates neuronal apoptosis in traumatic brain injury (TBI). First, we found 2ccPA suppressed neuronal apoptosis after the injury, and increased the immunoreactivity of tenascin-C (TN-C), an extracellular matrix protein by 2ccPA in the vicinity of the wound region. 2ccPA increased the mRNA expression levels of Tnc in primary cultured astrocytes, and the conditioned medium of 2ccPA-treated astrocytes suppressed the apoptosis of cortical neurons. The neuroprotective effect of TN-C was abolished by knockdown of TN-C. These results indicate that 2ccPA contributes to neuroprotection via TN-C from astrocytes in TBI.

The neuroprotective function of 2-carba-cyclic phosphatidic acid: Implications for tenascin-C via astrocytes in traumatic brain injury.

2-carba-cyclic phosphatidic acid (2ccPA) suppresses microglial and astrocyte inflammation for neuronal survival following traumatic brain injury. However, it remains unknown how 2ccPA regulates microglial activation. In this study, to elucidate the 2ccPA behavior in glial communication, we collected the astrocyte conditioned media (ACM) from primary astrocyte cultures that were treated by lipopolysaccharide (LPS) and 2ccPA and analyzed the alteration of microglial inflammation caused by the ACM treatment. The addition of the ACM derived from LPS- and 2ccPA-double treated astrocytes to microglia decreased the CD86 pro-inflammatory M1 microglia, which were upregulated with the ACM collected from astrocytes treated by LPS without 2ccPA, while the direct addition of LPS and 2ccPA to microglia failed to decrease the CD86 microglia to the basal level. We confirmed that the ACM from LPS- and 2ccPA-treated astrocytes increased the ratio of CD206 anti-inflammatory M2 microglia to total microglia, whereas direct treatment of microglia with LPS and 2ccPA had no effect on the CD206 microglia ratio, demonstrating the importance of astrocyte intervention in microglial polarization. In addition, we examined whether astrocytes modulate the 2ccPA-regulated proinflammatory cytokine production derived from microglia. The addition of the ACM from LPS- and 2ccPA-treated astrocytes to microglia remarkably canceled the LPS-induced upregulation of IL-1β, IL-6, and TNF-α secreted from microglia, while the direct addition of LPS and 2ccPA to microglia showed no affect. Therefore, our results indicate that astrocytes mediate the 2ccPA function to shift microglia towards the M2 phenotype by interfering with the polarization of M1 microglia and to suppress cytokine production.

2-carba-cyclic phosphatidic acid modulates astrocyte-to-microglia communication and influences microglial polarization towards an anti-inflammatory phenotype.

Effective blood coagulation prevents inflammation and neuronal loss after brain injury. 2-Carba-cyclic phosphatidic acid (2ccPA), a biotherapeutic for brain injury, inhibits blood extravasation resulting from blood-brain barrier breakdown. However, the hemostasis mechanism of 2ccPA remains unclear. We determined the effects of 2ccPA-injection on blood coagulation and fibrinolysis using a needle-induced brain injury model. 2ccPA suppressed the expression of platelet degranulation-related genes. Immediately after brain injury, 2ccPA increased CD41 platelet aggregation around the lesions and promoted fibrin aggregation. Additionally, 2ccPA supported fibrinolysis by upregulating plasminogen activator expression. These results suggest the acute effects of 2ccPA on brain hemostasis.

2-Carba cyclic phosphatidic acid regulates blood coagulation and fibrinolysis system for repair after brain injury.

Vitronectin (VN) is an extracellular matrix protein with a crucial role in regulating bone remodeling. In this study, we aimed to investigate the effect of VN deficiency in a mouse model of osteoporosis induced by ovariectomy (OVX). The findings revealed that the absence of VN led to an increase in the activity of tartrate-resistant acid phosphatase (TRAP), a marker for osteoclasts, in the plasma of OVX-operated mice. TRAP staining further demonstrated that VN deficiency resulted in a higher number of osteoclasts within the femurs of OVX-operated mice. X-ray micro-computed tomography analysis of the femurs in OVX-operated mice indicated that VN deficiency significantly suppressed the OVX-induced increase of marrow area and total volume of bone. Additionally, we assessed structural model index (SMI) and degree of anisotropy (DA) as indices of osteoporosis. The results showed that VN deficiency effectively attenuated the OVX-induced increase in SMI and DA among OVX-operated mice. In summary, our study demonstrates the vital role of VN in regulating osteoclastogenesis and bone remodeling in the mouse model of osteoporosis.

Mari Nakashima

Institute for Human Life Science

Ochanomizu University

Stab-Wound Mouse Model for Studying Hemorrhage and Inflammation in Traumatic Brain Injury