Cellular Localization and Temporal Elevation of Tumor Necrosis Factor-α, Interleukin-1α, and Transforming Growth Factor-β1 mRNA in Hippocampal Injury Response Induced by Trimethyltin

Abstract: In certain pathologic states, cytokine production may become spatially and temporally dysregulated, leading to their inappropriate production and potentially detrimental consequences. Tumor necrosis factor-α (TNF-α), interleukin (IL)-1, IL-6, and transforming growth factor-β (TGF-β) mediate a range of host responses affecting multiple cell types. To study the role of cytokines in the early stages of brain injury, we examined alterations in the 17-day-old mouse hippocampus during trimethyltin-induced neurodegeneration characterized by neuronal necrosis, microglia activation in the dentate, and astrocyte reactivity throughout the hippocampus. By 24 h after dosing, elevations in mRNA levels for TNF-α, IL-1α, IL-1β, and IL-6 mRNA were seen. TGF-β1 mRNA was elevated at 72 h. In situ hybridization showed that TNF-α and IL-1α were localized to the microglia, whereas TGF-β1 was expressed predominantly in hippocampal pyramidal cells. Intercellular adhesion molecule-1, EB-22, Mac-1, and glial fibrillary acidic protein mRNA levels were elevated within the first 3 days of exposure in the absence of increased inducible nitric oxide synthetase and interferon-γ mRNA. These data suggest that pro-inflammatory cytokines contribute to the progression and pattern of neuronal degeneration in the hippocampus.     

Translational event mediates differential production of tumor necrosis factor-alpha in hyaluronan-stimulated microglia and macrophages

Recent evidence has demonstrated that hyaluronan synthase 2 mRNA is up-regulated after brain ischemia. After a cerebral ischemic event, microglia and macrophages are the major inflammatory cells and are activated by hyaluronan (HA). However, it is unclear how these cells compare with regard to HA responsiveness. We show here that peritoneal macrophages and RAW 264.7 macrophages produced more than five- and 10-fold more tumor necrosis factor-alpha (TNF-alpha) than primary microglia and BV-2 microglia, respectively. Antibody blockade study showed that CD44, Toll-like receptor-4 receptor and the receptor for HA-mediated motility were responsible for HA-induced TNF-alpha release. Furthermore, HA induced higher levels of phosphorylated MAPK in RAW 264.7 cells when compared with BV-2 cells. HA-mediated TNF-alpha production required p38 MAPK, extracellular-regulated kinase and c-Jun N-terminal kinase phosphorylation in both cell types. The levels of HA-induced TNF-alpha mRNA expression in BV-2 cells were only twofold lower compared with RAW 264.7 cells, suggesting that a translational event is involved in the differential production of TNF-alpha. Western blot analysis revealed that HA treatment resulted in more rapid phosphorylation of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) and more effective dissociation of 4E-BP1 from eukaryotic initiation factor 4E in RAW 264.7 cells than in BV-2 cells. Additionally, HA-induced phosphorylation of 4E-BP1 was dependent on MAPK signaling, indicating that RAW 264.7 cells exhibited higher levels of hyperphosphorylated 4E-BP1 possibly due to the overactivation of MAPK. The results suggest that resident microglia and blood-derived monocytes/macrophages exhibit differential sensitivities in response to extracellular mediators after brain ischemia.     

Development of hematogenous pneumococcal meningitis in adult mice: the role of TNF-alpha

Bacterial penetration across the blood-brain barrier (BBB) into the central nervous system is the first step in development of meningitis. The role of tumor necrosis factor-alpha (TNF-alpha) in the penetration process was examined with peripheral infection of Streptococcus pneumoniae type 6. After intraperitoneal infection of S. pneumoniae type 6, the BBB opening was increased continuously from 6 h and the mice died of septic shock within 36 h due to bacterial overgrowth. The bacteria crossed the BBB and began to deposit in brain at 6 h post infection. There was strong staining of TNF-alpha on blood vessels of brain from 6 h to 24 h post infection. Anti-TNF-alpha antibody blocked both the BBB opening and the entrance of circulatory S. pneumoniae type 6 into brain, indicating that TNF-alpha played an important role in controlling the opening of BBB. Furthermore, an adult murine model of hematogenous pneumococcal meningitis was developed that is based on opening of the BBB by TNF-alpha and controlling the degree of bacteremia by cefazolin antibiotic. In conclusion, hematogenous meningitis developed as TNF-alpha initiated BBB opening, peripheral bacteria entered into the brain and formed bacterial emboli, and then progressed to meningitis.     

Protective effect of melatonin against transient global cerebral ischemia-induced neuronal cell damage via inhibition of matrix metalloproteinase-9

Aims

Melatonin possesses various pharmacological effects including neuroprotective effects against brain ischemia. Post-ischemic increases in matrix metalloproteinase-9 (MMP-9) expression and activity mainly contribute to neuronal damage by degradation of the extracellular matrix. This study was designed to examine whether melatonin has a neuroprotective effect and an influence on MMP-9 in transient global brain ischemia.

Main methods

Mice were subjected to 20 min of global brain ischemia and sacrificed 72 h later. Melatonin (30 mg/kg) was administered 30 min before and 2 h after ischemia as well as once daily until sacrifice.

Key findings

Hippocampal pyramidal cell damage after ischemia was significantly decreased by melatonin. As observed by zymography, melatonin inhibited the increase of MMP-9 activity after ischemia. In the brain sections, the increased gelatinase activity was mainly observed in the hippocampus after ischemia and melatonin also reduced gelatinase activity. The laminin and NeuN expression levels were reduced in the hippocampal CA1 and CA2 regions after ischemia, and melatonin reduced laminin degradation and neuronal loss. A TUNEL assay demonstrated that there were TUNEL-positive cells in the hippocampus and the number of TUNEL-positive cells was significantly decreased by melatonin. There was no difference in the ischemia-induced hippocampal neuronal damage between the vehicle- and melatonin-treated groups of MMP-9 knock-out mice.

Significance

These data demonstrate that melatonin suppressed the occurrence of neuronal injury, which might be partly due to its inhibitory effects on MMP-9 in addition to its anti-oxidative effects. MMP-9 may be an important key target of melatonin in neuroprotection against global ischemia.     

Immune control of Brucella abortus 2308 infections in BALB/c mice

BALB/c mice infected with Brucella abortus strain 2308 have 10-fold higher levels of bacteria during the plateau phase of infection (the time period when the number of colony-forming units in vivo remains consistent) than the more resistant C57BL/10 mice. This is due to a cessation of interferon-gamma (IFN-gamma) production that begins after the first week of infection and continues until the end of the plateau phase at least 6 weeks post infection. Despite the lack of IFN-gamma production during this time BALB/c mice are able to prevent an increase in bacterial colony-forming units. Here it was shown that both tumor necrosis factor (TNF)-alpha and CD8 T cells were involved in controlling bacterial numbers in BALB/c mice during this time. That is, neutralization of TNF-alpha or depletion of CD8 T cells with monoclonal antibodies resulted in a significant increase in the number of splenic colony-forming units recovered at 3 weeks post infection. In the absence of CD8 T cells there was also a significant increase in splenic macrophages. The role of TNF-alpha may depend upon the presence of interferon-gamma early in the infection since when TNF-alpha was neutralized in interferon-gamma gene knockout mice there was a marked increase in splenic macrophages, NK cells and neutrophils but not a significant increase in colony-forming units.     

Tumor necrosis factor-alpha from bone marrow-derived cells is not essential for the expression of adhesion molecules in lipopolysaccharide-induced nasal inflammation

Both the role and source of tumor necrosis factor (TNF-alpha) in lipopolysaccharide (LPS)-induced nasal inflammation were investigated using TNF-alpha gene deficient (TNF-alpha -/-) mice and chimeric mice that are TNF-alpha gene deficient only in bone marrow-derived cells. In the present study, intracellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) mRNA expression levels in the nasal mucosa were significantly decreased following intranasal instillation of LPS in TNF-alpha gene deficient mice compared to those in wild type mice. In contrast, ICAM-1 and VCAM-1 mRNA expressions were not significantly decreased although TNF-alpha mRNA expression was dramatically decreased in TNF-alpha gene deficient bone marrow-transplanted-chimeric (TNF-alpha -/--->+/+) mice compared to those in wild type bone marrow-transplanted-control (TNF-alpha +/+-->+/+) mice. These results indicate that the elevation of TNF-alpha mRNA in the nasal mucosa is mainly originated from bone marrow-derived cells. However, even low expression of TNF-alpha at local inflammation sites is sufficient to induce the expression of adhesion molecules in acute LPS-induced experimental rhinitis.     

Protective effect of resveratrol against neuronal damage following transient global cerebral ischemia in mice

Resveratrol (3,5,4'-trihydroxystilbene) is a natural polyphenol which is rich in grape seeds and skin. Several studies have revealed that resveratrol possesses neuroprotective effects. In the case of global brain ischemia, there are few reports regarding the protective effect of resveratrol. Therefore, the influence of resveratrol on neuronal damage after transient global brain ischemia remains to be clarified. In the current study, C57BL/6 black mice were subjected to 20 min of transient global brain ischemia and followed by 72 h of reperfusion. Resveratrol (20 or 40 mg/kg, once daily, dissolved in 0.5% carboxymethylcellulose) was administered orally for 7 days before ischemia and daily until the mice were euthanized. The effect of lower or higher dose of resveratrol on neuronal damage, matrix metalloproteinase (MMP) activity and in situ DNA fragmentation (TUNEL) assay in the hippocampus after global ischemia was examined. Neuronal damages were remarkable in CA1 and CA2 pyramidal cell layers after global ischemia. In resveratrol-treated mice (40 mg/kg), neuronal damage was significantly reduced compared with vehicle-treated mice. Mice treated with resveratrol showed reduced MMP-9 activity. Resveratrol also inhibited TUNEL staining. These data suggest that resveratrol, a natural polyphenol, reduces hippocampal neuronal cell damage following transient global ischemia by reducing MMP-9 activity.     

Effects of nitrobenzylthioinosine on neuronal injury, adenosine levels, and adenosine receptor activity in rat forebrain ischemia

Adenosine levels increase in brain during cerebral ischemia, and adenosine has receptor-mediated neuroprotective effects. This study was performed to test the hypothesis that nitrobenzylthioinosine (NBMPR), a selective and potent inhibitor of one adenosine transporter subtype termed ENT1, or es, can protect against ischemic neuronal injury by enhancing adenosine levels and potentiating adenosine receptor-mediated effects, including attenuation of the cellular production and release of tumor necrosis factor-alpha (TNF-alpha). In rats, the phosphorylated prodrug form of NBMPR, NBMPR-phosphate, or saline was administered by intracerebroventricular injection 30 min before forebrain ischemia. Seven days following the ischemic episode, rats were killed, and neuronal damage in the CA1 region of the hippocampus was assessed. The number of pyramidal neurons was significantly (p < 0.001) greater in the NBMPR-P treatment group. A trend toward protection was still evident at 28 days postreperfusion. Adenosine increased significantly during ischemia to levels eight- to 85-fold above basal. NBMPR-P treatment did not cause statistically significant increases in ischemic adenosine levels; however, this treatment tended to increase adenosine levels in all brain regions at 7 min postreperfusion. Ischemia-induced expression of TNF-alpha was not altered by NBMPR-P treatment, and the nonselective adenosine receptor antagonist 8-(p-sulfophenyl) theophylline did not abolish the neuroprotective effects of NBMPR-P treatment. These data indicate that NBMPR can protect CA1 pyramidal neurons from ischemic death without statistically significant effects on adenosine levels or adenosine receptor-mediated inhibition of the proinflammatory cytokine TNF-alpha.     

Protective Effect of Oren-gedoku-to Against Induction of Neuronal Death by Transient Cerebral Ischemia in the C57BL/6 Mouse

We examined the neuroprotective effects of oren-gedoku-to (TJ15), a herbal medicine, after transient forebrain ischemia. Transient forebrain ischemia was induced by occlusion of both common carotid arteries for 15 min in C57BL/6 mice treated with TJ15. In the control ischemic group without TJ15 treatment, histologic examination of brain tissue collected seven days after reperfusion showed death of pyramidal cells in CA2-3 area of the hippocampus, unilaterally or bilaterally. In mice treated with oral TJ15 (845 mg/kg/day) for five weeks, the frequency of ischemic neuronal death was significantly lower. Immunohistochemistry for Cu/Zn-superoxide dismutase (Cu/Zn-SOD) showed strongly reactive astrocytes in the hippocampus of ischemic mice treated with TJ15. Damage to nerve cells by free radicals plays an important role in the induction of neuronal death by ischemia-reperfusion injury. Our results suggest that TJ15 protects against ischemic neuronal death by increasing the expression of Cu/Zn-SOD and suggest that oren-gedoku-to reduces the exposure of hippocampal neurons to oxidative stress.     

Inductin of neuron-derived orphan receptor-1 in the dentate gyrus of the hippocampal formation following transient global ischemia in the rat

Neuron-derived orphan receptor (NOR-1) is a member of the thyroid/steroid receptor superfamily that was originally identified in forebrain neuronal cells undergoing apoptosis. In addition to apoptotic stimuli, activation of several signal transduction pathways including direct neuronal depolarization regulates the expression of NOR-1. In this study we tested whether the expression of NOR-1 is changed following transient ischemic injury in the adult rat brain. NOR-1 mRNA increased rapidly in the dentate gyrus of the hippocampal formation and piriform cortex 3 h after transient global ischemia and returned to basal level at 6 h. On the other hand, oxygen-glucose deprivation of cultured cerebral cortical neurons did not alter the expression of NOR-1. These results suggest that expression of NOR-1 is differentially regulated in different brain regions in response to globally applied brain ischemia, but that hypoxia is not sufficient to induce its expression.     

Exuberant inflammation in nicotinamide adenine dinucleotide phosphate-oxidase-deficient mice after allogeneic marrow transplantation

We have shown that NO and superoxide (O-*2)contribute to donor T cell-dependent lung dysfunction after bone marrow transplantation (BMT) in mice. We hypothesized that inhibiting superoxide production during inducible NO synthase induction would suppress oxidative/nitrative stress and result in less severe lung injury. Irradiated mice lacking the phagocytic NADPH-oxidase (phox(-/-)), a contributor to superoxide generation, were conditioned with cyclophosphamide and given donor bone marrow in the presence or absence of inflammation-inducing allogeneic spleen T cells. On day 7 after allogeneic BMT, survival, weight loss, and indices of lung injury between phox(-/-) and wild-type mice were not different. However, the majority of macrophages/monocytes from phox(-/-) mice given donor T cells produced fewer oxidants and contained less nitrotyrosine than cells obtained from T cell-recipient wild-type mice. Importantly, suppressed oxidative stress was associated with marked infiltration of the lungs with inflammatory cells and was accompanied by increased bronchoalveolar lavage fluid levels of the chemoattractants monocyte chemoattractant protein-1 and macrophage-inflammatory protein-1alpha and impaired clearance of recombinant mouse macrophage-inflammatory protein-1beta from the circulation. Furthermore, cultured macrophages/monocytes from NADPH-deficient mice produced 3-fold more TNF-alpha compared with equal number of cells from NADPH-sufficient mice. The high NO production was not modified during NADPH-oxidase deficiency. We conclude that phox(-/-) mice exhibit enhanced pulmonary influx of inflammatory cells after BMT. Although NO may contribute to increased production of TNF-alpha in phox(-/-) mice, the data suggest that NADPH-oxidase-derived oxidants have a role in limiting inflammation and preventing lung cellular infiltration after allogeneic transplantation.     

Secretion of interleukin-1beta by astrocytes mediates endothelin-1 and tumour necrosis factor-alpha effects on human brain microvascular endothelial cell permeability

Evidence suggests that endothelin-1 (ET-1) plays an essential role in brain inflammation. However, whether ET-1 contributes directly to blood-brain barrier (BBB) breakdown remains to be elucidated. Using an in vitro BBB model consisting of co-cultures of human primary astrocytes and brain microvascular endothelial cells (BMVECs), we first investigated the expression of ET-1 by BMVECs upon stimulation with tumour necrosis factor (TNF)-alpha, which plays an essential role in the induction and synthesis of ET-1 during systemic inflammatory responses. Increased ET-1 mRNA was detected in the human BMVECs 24 h after TNF-alpha treatment. This was correlated with an increase in ET-1 levels in the culture medium, as determined by sandwich immunoassay. Both TNF-alpha and ET-1 increased the permeability of human BMVECs to a paracellular tracer, sucrose, but only in the presence of astrocytes. The increase in BMVEC permeability by TNF-alpha was partially prevented by antibody neutralization of ET-1 and completely by monoclonal antibody against IL-1beta. Concomitantly, TNF-alpha induced IL-1beta mRNA expression by astrocytes in co-culture and this effect was partially prevented by ET-1 antibody neutralization. In parallel experiments, treatment of human primary astrocytes in single cultures with ET-1 for 24 h induced IL-1beta mRNA synthesis and IL-1beta protein secretion in the cell culture supernatant. Taken together, these results provide evidence for paracrine actions involving ET-1, TNF-alpha and IL-1beta between human astrocytes and BMVECs, which may play a central role in BBB breakdown during CNS inflammation.     

Activation of poly(ADP-ribose) polymerase in the rat hippocampus may contribute to cellular recovery following sublethal transient global ischemia

We have investigated the role of poly(ADP-ribose) polymerase (PARP) activation in rat brain in a model of sublethal transient global ischemia. Adult male rats were subjected to 15 min of ischemia with brain temperature reduced to 34 degrees C, followed by 1, 2, 4, 8, 16, 24, and 72 h of reperfusion. PARP mRNA expression was examined in the hippocampus using quantitative RT-PCR, northern blot analysis, and in situ hybridization. Protein expression was assessed using western blot analysis. PARP enzymatic activity was investigated by measuring nuclear [3H]NAD incorporation. The presence of poly(ADP-ribose) polymers was assessed immunocytochemically. Although PARP mRNA and protein expressions were not altered after ischemia, enzymatic activity was increased 4.37-fold at 1 h (p < 0.05 vs. sham) and 1.73-fold (p < 0.05 vs. sham) at 24 h of reperfusion. Immunostaining demonstrated the presence of poly(ADP-ribose) polymers in CA1 neurons. Cellular NAD+ levels were not significantly altered at any time point. Furthermore, systemic administration of 3-aminobenzamide (30 mg/kg), a PARP inhibitor, prevented the increase in PARP activity at 1 and 24 h of reperfusion, significantly decreased the number of surviving neurons in the hippocampal CA1 region 72 h after ischemia (p < 0.01 vs. sham), and increased DNA single-strand breaks assessed as DNA polymerase I-mediated biotin-dATP nick-translation (PANT)-positive cells (p < 0.01 vs. sham). Furthermore, using an in vitro DNA repair assay, 3-aminobenzamide (30 mg/kg) was shown to block DNA base excision repair activity. These data suggest that the activation of PARP, without subsequent NAD+ depletion, following mild transient ischemia may be neuroprotective in the brain.     

Transient Global Ischemia Alters NMDA Receptor Expression in Rat Hippocampus: Correlation with Decreased Immunoreactive Protein Levels of the NR2A/2B Subunits, and an Altered NMDA Receptor Functionality

Abstract: We investigated the gene expression levels, the immunoreactive protein prevalence, and the functional activity of N -methyl- d -aspartate (NMDA) receptor complexes at early times after severe global ischemia challenge in rats. The mRNA expression levels for the NR2A and NR2B subunits of NMDA receptors changed to different degrees within different subregions of the hippocampus after reperfusion with respect to sham-operated control. No significant change in expression was observed in the vulnerable CA1 subfield at or before 6 h after challenge for either receptor subunit, although changes in expression in other hippocampal subfields were observed. At 12 and 24 h after challenge, significant decreases in expression for both subunits were found in the vulnerable CA1 subfield, as well as in other hippocampal regions. At the protein level, a significant decrease in the amount of NR2A/NR2B immunoreactivity in the total hippocampus was observed at both 6 and 24 h after reperfusion compared with sham control. Electrophysiological assessment of single-channel NMDA receptor activity in the CA1 subfield indicates that the main conductance state of NMDA receptor channels is maintained 6 h after challenge, although by 18–24 h after challenge, this main conductance state is rarely observed. The NMDA receptor component of the excitatory postsynaptic field potential was found to be significantly diminished from sham control 24 h after challenge, such that only ∼10% of the sham response remained, but was not significantly altered from sham control at 6 h after challenge. These results indicate that decreases in the expression levels, the immunoreactive protein prevalence, and that alterations in the functionality of NMDA receptors occur in the hippocampus at early times after severe transient global ischemia.     

TLR2 has a detrimental role in mouse transient focal cerebral ischemia

A significant up-regulation of Toll-like-receptor (TLR) mRNAs between 3 and 48 h reperfusion time after induction of transient focal cerebral ischemia for 1h was revealed by applying global gene expression profiling in postischemic mouse brains. Compared to TLR4 and TLR9, TLR2 proved to be the most significantly up-regulated TLR in the ipsilateral brain hemisphere. TLR2-protein was found to be expressed mainly in microglia in the postischemic brain tissue, but also in selected endothelial cells, neurons, and astrocytes. Additionally, TLR2-related genes with pro-inflammatory and pro-apoptotic capabilities were induced. Therefore we hypothesized that TLR2-signaling could exacerbate the primary brain damage after ischemia. Two days after induction of transient focal cerebral ischemia (1h), we found a significant decrease of the infarct volume in TLR2 deficient mice compared to wild type mice (75+/-5 vs. 42+/-7 mm(3)). We conclude that TLR2 up-regulation and TLR2-signaling are important events in focal cerebral ischemia and contribute to the deterioration of ischemic damage.     

Expression of antigen on mature lymphocytes is required to induce T cell tolerance by gene therapy

Expression of a retrovirally encoded allogeneic MHC class I gene in bone marrow-derived cells can be used to induce tolerance to the product of the retrovirally transduced gene. In this work we examined whether expression of a retrovirally transduced allogeneic MHC class I gene in bone marrow-derived cells from recombinase-activating gene-1 (RAG-1)-deficient mice was sufficient to induce tolerance when transplanted into conditioned hosts together with bone marrow from MHC-matched wild-type mice. Reconstitution of mice with either MHC-matched RAG-1-deficient or wild-type bone marrow transduced with the allogeneic MHC class I gene H-2K(b) led to long-term expression of K(b) on the surface of bone marrow-derived hematopoietic lineages. T cells from mice reconstituted with H-2K(b)-transduced wild-type bone marrow were tolerant to K(b). In contrast, expression of K(b) in the periphery of mice reconstituted with a mixture of retrovirally transduced RAG-1-deficient bone marrow and mock-transduced wild-type bone marrow fell below detectable levels by 4 wk after transplantation. T cells that developed in these mice appeared to be hyporesponsive to K(b), demonstrating that expression of K(b) on bone marrow-derived APCs was not sufficient to induce tolerance. Our data suggest that induction of tolerance in molecular chimeras requires expression of the retrovirally transduced allogeneic MHC Ag on the surface of mature lymphocytes that populate the host thymus.     

The PPARδ agonist GW0742 inhibits neuroinflammation,but does not restore neurogenesis or prevent early delayed hippocampal-dependent cognitive impairment after whole-brain irradiation

Brain tumor patients often develop cognitive impairment months to years after partial or fractionated whole-brain irradiation (WBI). Studies suggest that neuroinflammation and decreased hippocampal neurogenesis contribute to the pathogenesis of radiation-induced brain injury. In this study, we determined if the peroxisomal proliferator-activated receptor (PPAR) δ agonist GW0742 can prevent radiation-induced brain injury in C57Bl/6 wild-type (WT) and PPARδ knockout (KO) mice. Dietary GW0742 prevented the acute increase in IL-1β mRNA and ERK phosphorylation measured at 3 h after a single 10-Gy dose of WBI; it also prevented the increase in the number of activated hippocampal microglia 1 week after WBI. In contrast, dietary GW074 failed to prevent the radiation-induced decrease in hippocampal neurogenesis determined 2 months after WBI in WT mice or to mitigate their hippocampal-dependent spatial memory impairment measured 3 months after WBI using the Barnes maze task. PPARδ KO mice exhibited defects including decreased numbers of astrocytes in the dentate gyrus/hilus of the hippocampus and a failure to exhibit a radiation-induced increase in activated hippocampal microglia. Interestingly, the number of astrocytes in the dentate gyrus/hilus was reduced in WT mice, but not in PPARδ KO mice 2 months after WBI. These results demonstrate that, although dietary GW0742 prevents the increase in inflammatory markers and hippocampal microglial activation in WT mice after WBI, it does not restore hippocampal neurogenesis or prevent early delayed hippocampal-dependent cognitive impairment after WBI. Thus, the exact relationship between radiation-induced neuroinflammation, neurogenesis, and cognitive impairment remains elusive.     

Effect of peptide Semax and its C-terminal fragment PGP on Vegfa gene expression during incomplete global cerebral ischemia in rats

Vascular endothelial growth factor (VEGF-A) is hypoxia-inducible signal glycoprotein. VEGF-A induces vascular endothelial cell proliferation, which leads to the reconstitution of the vascular network in brain regions damaged by ischemia. However, this protein is also involved in the processes of inflammation and edema in early stages of ischemia. The synthetic peptide Semax has neuroprotective and anti-inflammatory properties and is actively used in the treatment of cerebral ischemia. We have previously shown that Semax reduces vascular injury and activates the mRNA synthesis of neurotrophins and their receptors during global cerebral ischemia in rats. In this work, we studied the effect of Semax and its C-terminal Pro-Gly-Pro tripeptide on Vegfa mRNA expression in different regions of the rat brain after 0.5, 1, 2, 4, 8, 12 and 24 h, which is the irreversible occlusion of the common carotid arteries. It was shown that ischemia increases the levels of Vegfa mRNA in rat brains (4 h after occlusion in cerebellum, cerebral cortex, and hippocampus; 8 h after occlusion in the cortex and hippocampus; and 24 h after occlusion in the cortex). Treatment with Semax reduces the levels of Vegfa mRNA in the frontal cortex (4, 8 and 12 h after occlusion) and the hippocampus (2 and 4 h after occlusion). The effect of PGP on the Vegfa gene expression was almost negligible. It was shown that Semax prevents the activating effect of hypoxia on the expression of the Vegfa gene at early stages of global cerebral ischemia. In turn, an increase in the level of Vegfa mRNA in the hippocampus 24 h after occlusion and Semax administration apparently reflects the neuroprotective properties of the drug.     

Absence of host tumor necrosis factor receptor 1 attenuates manifestations of idiopathic pneumonia syndrome

The interaction of TNF-alpha with TNF receptor 1 (TNFR1) activates several signal transduction pathways that lead to apoptosis or NF-kappa B-dependent inflammation and immunity. We hypothesized that host TNFR1 expression contributes to noninfectious lung injury and inflammation commonly observed after bone marrow transplantation (BMT), termed idiopathic pneumonia syndrome (IPS). C57BL/6 TNFR1-sufficient (TNFR1(+/+)) and -deficient (TNFR1(-/-)) mice were total body irradiated with or without cyclophosphamide conditioning and were given bone marrow plus IPS-inducing donor spleen T cells from B10.BR wild-type mice. TNFR1(-/-) recipient mice exhibited improved early post-BMT survival associated with decreased permeability edema. In addition, the low lung compliance measured in anesthetized, ventilated TNFR1(+/+) mice on day 7 after BMT was restored to baseline during TNFR1 deficiency. Importantly, bronchoalveolar lavage fluid (BALF) inflammatory cells from TNFR1(-/-) vs. TNFR1(+/+) mice generated less nitric oxide (.NO) and nitrating species and exhibited suppressed programmed cell death as assessed using flow cytometry. However, cellular infiltration and levels of proinflammatory cytokines and chemokines were generally higher in BALF collected on day 7 after BMT from TNFR1(-/-) compared with TNFR1(+/+) recipient mice. Our results support a major role of host TNFR1 in regulation of .NO production and lung dysfunction after allogeneic BMT.