Tumor Necrosis Factor Synthesis Research Articles

Synthesis of tumor necrosis factor α for use as a mirror-image phage display target.

Tumor Necrosis Factor alpha (TNFα) is an inflammatory cytokine that plays a central role in the pathogenesis of chronic inflammatory disease. Here we describe the chemical synthesis of l-TNFα along with the mirror-image d-protein for use as a phage display target. The synthetic strategy utilized native chemical ligation and desulfurization to unite three peptide segments, followed by oxidative folding to assemble the 52 kDa homotrimeric protein. This synthesis represents the foundational step for discovering an inhibitory d-peptide with the potential to improve current anti-TNFα therapeutic strategies.

Pentoxifylline for Diabetic Nephropathy: an Important Opportunity to Re-purpose an Old Drug?

Diabetic nephropathy, or diabetic kidney disease (DKD), is the most serious complication of diabetes mellitus (DM). Despite recent advances in therapy, DKD still often progresses to end-stage renal disease (ESRD). Recent studies have suggested that pentoxifylline (PTX) may be efficacious in the treatment of DKD. PTX is a rheologic modifier approved for use in the USA for the symptomatic relief of claudication. It competitively inhibits phosphodiesterase (PDE), resulting in increased intracellular cyclic AMP (cAMP), activation of protein kinase A (PKA), inhibition of interleukin (IL) and tumor necrosis factor (TNF) synthesis, and reduced inflammation. PTX improves red blood cell deformability, reduces blood viscosity, and decreases platelet aggregation. In combination with renin-angiotensin-aldosterone (RAAS) blockers, PTX may help prevent progression to ESRD in patients with DKD. This review focuses on the possible mechanisms of action of PTX in DKD and studies suggesting possible efficacy of this old drug for a new indication.

Endogenous microparticles drive the proinflammatory host immune response in severely injured trauma patients.

Severe trauma affects the immune system, which in its turn is associated with poor outcome. The mediators driving the immune responses in trauma are largely unknown. The aim of this study was to investigate the role of endogenous microparticles (MPs) in mediating the immune response following severe trauma. A prospective, observational substudy of the ACIT II (Activation of Coagulation and Inflammation in Trauma II) study was performed at our academic level I trauma center. Adult multiple-trauma patients with an injury severity score of 15 or higher were included between May 2012 and June 2013. Ex vivo whole-blood stimulation with lipopolysaccharide was performed on aseptically collected patient plasma containing MPs and in plasma depleted of MPs. Flow cytometry and transmission electronic microscopy were performed on plasma samples to investigate the numbers and cellular origin of MPs. Healthy individuals served as a control group. Ten trauma patients and 10 control subjects were included. Trauma patients were significantly injured with a median injury severity score of 19 (range, 17-45). Patients were neither in shock nor bleeding. On admission to the hospital, the host response to bacterial stimulation was blunted in trauma patients compared with control subjects, as reflected by decreased production of interleukin 6 (IL-6), IL-10, and tumor necrosis factor α (P < 0.001). In trauma patients, MP-positive plasma was associated with a significantly higher synthesis of IL-6 and tumor necrosis factor α compared with plasma depleted from MPs (P = 0.047 and 0.002, respectively). Compared with control subjects, the number of circulating MPs was significantly decreased in trauma patients (P = 0.009). Most MPs originated from platelets. Multiple cellular protrusions, which result in MP formation, were observed in plasma from trauma patients, but not in control subjects. On admission, trauma patients have a reduced immune response toward endotoxin challenge, which is, at least in part, mediated by MPs, which circulate in low numbers and in early stages. Most MPs originate from platelets, which indicates that these cells may be the most important source of MPs involved in initiating an inflammatory host response after injury.

Localization of α7 nicotinic acetylcholine receptor mRNA and protein within the cholinergic anti-inflammatory pathway

Electrical stimulation of the vagus nerve attenuates tumor necrosis factor (TNF) synthesis by macrophages and reduces the systemic inflammatory response. Current evidence suggests that the α7 nicotinic acetylcholine receptor present in the celiac/superior mesenteric ganglia is a key component in vagus nerve signaling to the spleen; however, there is currently no direct anatomical evidence that the α7 receptor is present in the murine celiac/superior mesenteric ganglia. Our study addresses this deficiency by providing anatomical evidence that the α7 receptor is expressed within the celiac/superior mesenteric ganglia and splenic nerve fibers using immunohistochemistry and quantitative polymerase chain reaction (qPCR). α7 receptor mRNA is highly expressed in the celiac/superior mesenteric ganglia and at low levels in the spleen compared to the brain. Double-labeling for α7 and tyrosine hydroxylase shows that α7 receptor protein is present on noradrenergic neurons within the ganglia and prejunctionally on noradrenergic nerve fibers within the spleen. The α7 receptor in the ganglia provides a possible location for the action of α7-selective agonists, while prejunctional α7 receptor expressed on splenic nerves may induce an increase in norepinephrine release in a positive feedback system enhanced by lymphocyte-derived acetylcholine.

THU0114 The Loss of S100A4 Prevents Joint Destruction and Systemic Bone Loss in hTNFtg Mouse Model

BackgroundOur previous studies demonstrated increased levels of S100A4 protein in sera, synovial fluid and synovial membrane of patients with rheumatoid arthritis (RA) compared to osteoarthritis. S100A4 regulates apoptosis and induces...

Analsysis of frequency of tuberculosis in smokers

Introduction. Smoking and tuberculosis are among the most important problems of public health. Smoking and tuberculosis are responsible for 5 million and 2 million deaths per year, respectively, whereas smoking is responsible for half a million deaths in patients with tuberculosis. Discussion and Review of Literature. Nicotine is a significant suppressor of function of macrophages, dendritic cells and T-cells, which explains the immunosuppressive features of smoking that help develop the infection. Tobacco smoke contains many substances with immunomodulatory effects, including nicotine, carbon monoxide, acrolein, peroxynitrite and many others. The dominant immune and pathophysiological mechanism is the reduction of synthesis of tumor necrosis factor in lung macrophages, leading to increased susceptibility of persons who are exposed to tobacco smoke for developing active tuberculosis after infection and increased susceptibility to the development of other infections, such as infections of Gram-negative bacteria. Based on epidemiological studies and studies on this problem in the past 50 years, the World Health Organization has published the finding that smoking increases the risk of infection with M. tuberculosis, increases the risk of progression of infection to active disease and the risk of death. The prevalence of tuberculosis is higher in smokers and former smokers than in nonsmokers. The risk of tuberculosis depends on the number of cigarettes smoked and length of period the person has been a smoker. Passive smoking accelerates the development of active tuberculosis. in children who live with persons suffering from active tuberculosis, Conclusion. Given the multiple consequences of the association between smoking and tuberculosis, prevention of smoking may be an important measure in the control of tuberculosis.

Aldosterone induces p21‐regulated apoptosis via increased synthesis and secretion of tumour necrosis factor‐α in human proximal tubular cells

Summary Aldosterone has been shown to mediate p21‐dependent cellular senescence in rat kidney proximal tubules in vivo and in cultured human proximal tubular cells. The p21‐induced senescent cells express higher levels of apoptotic cytokines, such as tumour necrosis factor (TNF)‐α compared with non‐senescent cells. The aim of the present study was to investigate the hypothesis that aldosterone increases proximal tubular apoptosis by increasing the secretion of apoptosis–inducing factors through a p21‐dependent mechanism. Human proximal tubular cells were incubated with aldosterone (10 nmol/L) and cell senescence was detected by senescence‐associated β‐galactosidase staining and expression of p21. Apoptosis was analysed by terminal deoxyribonucleotidyl transferase‐mediated dUTP–digoxigenin nick end‐labelling and annexin/propidium iodide staining, whereas p21 localization was determined by immunofluorescence. Exposure of cells to aldosterone for 3 or 5 days increased senescence–associated β‐galactosidase staining, p21 and TNF‐α mRNA expression and secretion of TNF‐α into the culture medium. These changes were abolished by gene silencing of p21. Aldosterone failed to increase the number of apoptotic cells on day 3, but did increase them on day 5. A neutralizing antibody against TNF‐α prevented the aldosterone‐induced apoptotic changes. Aldosterone did not affect localization of p21. These findings indicate that aldosterone increases TNF‐α synthesis and secretion in proximal tubular cells via p21/senescence–dependent cell phenotypic changes and that the TNF‐α secreted plays an important role as a paracrine factor in mediating cell apoptosis, indicating a possible involvement in aldosterone‐induced renal damage.

Short Double-Stranded RNA with Immunostimulatory Activity: Sequence Dependence

Small interfering RNAs (siRNA) are able to activate the mammalian innate immune system depending on their structure, sequence, and method of delivery. The immunostimulatory activity of double-stranded RNA can be applied to antiviral and antitumor therapy. Here we identified a set of 19-bp RNA duplexes with 3-nucleotid overhangs in the 3' ends that display immunostimulating activity (here and after immunostimulating RNA, or isRNA) and studied their sequence/activity relationships. It was found that the introduction of substitutions in the middle part of the isRNA sequence (10-16 positions counting from the 5' end of strand 1) does not alter the antiproliferative activity, while substitutions in the 3' end region of isRNA substantially reduce it. isRNAs efficiently inhibit the proliferation of human oral epidermoid carcinoma cells [half-maximal inhibitory concentration (IC(50)) values varied from 10 to 100 nM]. Our research demonstrated that antiproliferative effects of isRNAs are related to cell growth arrest, rather than the induction of apoptosis. These isRNAs strongly stimulate the synthesis of interferon-α (IFN-α), and to a lesser extent the synthesis of tumor necrosis factor (TNF-α) and interleukin-6 (IL-6), in adherent peripheral blood mononuclear cells. An intravenous injection of isRNA/Lipofectamine complexes into C57BL mice increases IFN-α and IL-6 levels in the blood serum up to 15-fold and 3-fold, respectively, compared to the control mice. The results obtained clearly demonstrate the pronounced immunostimulatory and antiproliferative properties of the isRNAs under study. Hence, these short double-stranded RNAs can be considered as potential agents for the therapy of oncological and viral diseases.

In vivo hydroquinone exposure causes tracheal hyperresponsiveness due to TNF secretion by epithelial cells

Hydroquinone (HQ) is the main oxidative substance in cigarette smoke and a toxic product of benzene biotransformation. Although the respiratory tract is an inlet pathway of HQ exposure, its effect on airway muscle responsiveness has not been assessed. We thus investigated the effects of low dose in vivo HQ-exposure on tracheal responsiveness to a muscarinic receptor agonist. Male Swiss mice were exposed to aerosolised 5% ethanol/saline solution (HQ vehicle; control) or 0.04ppm HQ (1h/day for 5 days) and tracheal rings were collected 1h after the last exposure. HQ exposure caused tracheal hyperresponsiveness to methacholine (MCh), which was abolished by mechanical removal of the epithelium. This hyperresponsiveness was not dependent on neutrophil infiltration, but on tumour necrosis factor (TNF) secretion by epithelial cells. This conclusion was based on the following data: (1) trachea from HQ-exposed mice presented a higher amount of TNF, which was abrogated following removal of the epithelium; (2) the trachea hyperresponsiveness and TNF levels were attenuated by in vivo chlorpromazine (CPZ) treatment, an inhibitor of TNF synthesis. The involvement of HQ-induced TNF secretion in trachea mast cell degranulation was also demonstrated by the partial reversion of tracheal hyperresponsiveness in sodium cromoglicate-treated animals, and the in vivo HQ-exposure-induced degranulation of trachea connective tissue and mucosal mast cells, which was reversed by CPZ treatment. Our data show that in vivo HQ exposure indirectly exacerbates the parasympathetic-induced contraction of airway smooth muscle cells, mediated by TNF secreted by tracheal epithelial cells, clearly showing the link between environmental HQ exposure and the reactivity of airways.

Identification and immunogenicity of two new HLA-A*0201-restricted CD8+ T-cell epitopes on dengue NS1 protein

Immunopathogenesis of dengue virus (DEN) infection remains poorly studied. Identification and characterization of human CD8(+) T-cell epitopes on DEN are necessary for a better understanding of the immunopathogenesis of dengue infection and would facilitate the development of immunotherapy and vaccines to protect from dengue infection. Here, we identified two new HLA-A*0201-restricted CD8(+) T-cell epitopes, DEN-4 NS1(990)(-998) and DEN-4 NS1(997)(-1005) that are conserved in three or four major DEN serotypes, respectively. Unexpectedly, we found that immunization of HLA-A*0201 transgenic mice with DEN-4 NS1(990)(-998) or DEN-4 NS1(997)(-1005) epitope peptide induced de novo synthesis of tumor necrosis factor (TNF)-α and IFN-γ, two important pro-inflammatory molecules that are hard to be detected directly without in vitro antigenic re-stimulation. Importantly, we demonstrated that CD8(+) T cells specifically activated by DEN-4 NS1(990)(-998) or DEN-4 NS1(997)(-1005) epitope peptide induced de novo synthesis of perforin. Furthermore, we observed that DEN-4 NS1(990)(-998) or DEN-4 NS1(997)(-1005)-specific CD8(+) T cells capable of producing large amounts of perforin, TNF-α and IFN-γ preferentially displayed CD27(+)CD45RA(-), but not CD27(-)CD45RA(+), phenotypes. This study, therefore, suggested the importance of synergistic effects of pro-inflammatory cytokines and cytotoxic molecules which were produced by dengue-specific CD8(+) T cells in immunopathogenesis or anti-dengue immunity during dengue infection.

Involvement of visfatin in palmitate-induced upregulation of inflammatory cytokines in hepatocytes

Free fatty acids (FFAs) lead to the activation of inflammatory pathways related to the induction of insulin resistance. Visfatin is known to play a role in obesity-related metabolic diseases and inflammatory conditions. Here, the role of visfatin in FFA-induced inflammation was investigated in hepatocytes. The following factors were examined: (1) the protein and messenger RNA (mRNA) expression of visfatin in the liver tissue of insulin-resistant rats and in (2) in HepG2 cells treated with palmitate, (3) the palmitate-induced mRNA expression and protein synthesis of interleukin-6 and tumor necrosis factor–α in HepG2 cells transfected with visfatin-specific small interfering RNA, and (4) the expression of visfatin in HepG2 cells treated with a nuclear factor–κB (NF-κB) inhibitor (SN50) and infected with Ad-IκBα. The protein and mRNA levels of visfatin were significantly higher in insulin-resistant rat liver tissue compared with the control group. Visfatin expression and protein synthesis significantly increased in HepG2 cells treated with palmitate in a time- and concentration-dependent manner. Visfatin-specific small interfering RNA significantly decreased the palmitate-induced mRNA expression and protein synthesis of interleukin-6 and tumor necrosis factor–α. A NF-κB inhibitor induced the downregulation of visfatin in HepG2 cells following treatment with palmitate. HepG2 cells infected with Ad-IκBα showed decreased expression of visfatin following treatment with palmitate. The expression of visfatin is closely associated with the expression of proinflammatory cytokines in FFA-induced inflammation and is significantly decreased by NF-κB inhibition in HepG2 cells. Visfatin may play a role in FFA-induced inflammation in hepatocytes through the NF-κB pathway.

Effect of recombinant interleukin-10 on some haematological and biochemical parameters in a rat endotoxaemic model

Recombinant interleukin-10 (rIL10) has been found to suppress the synthesis of tumour necrosis factor (TNF), interleukin-1 (IL-1), interleukin-6 (IL-6) and tissue factor and to improve survival from experimental sepsis. The aim of this study was to evaluate the protective effect of rIL-10 on lipopolysaccharide-(LPS-) induced haematological and biochemical disturbances in rats. In the present study, 40 rats were used and divided equally into four groups. Group 1 (control group, C) was treated with 0.9% saline. Group 2: LPS was injected intravenously (1.6 mg/100 g), Group 3 received rIL10 treatment (125 μg/kg) 2 min before 0.9% saline injection, Group 4 received rIL10 treatment 2 min before endotoxin treatment. When compared with the controls, platelet count, leukocyte count (with a marked neutrophilia and lymphopenia) and fibrinogen were decreased, while activated partial thromboplastin time (APTT) and prothrombin time (PT) were prolonged in the endotoxaemic rats. In addition, LPS caused statistically significant increases in plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities as well as creatinine, cholesterol and triglyceride concentrations, while it caused a statistically significant decrease in glucose, total protein and albumin levels as compared to the control group. On the other hand, rIL10 significantly suppressed disturbances in the haematological and biochemical parameters associated with endotoxaemia. As a result, rIL10 may be efficacious in preventing haematological disorders, tissue damage and changes in lipid, protein and carbohydrate metabolism in endotoxaemia.

Bupropion and Panic Disorder: Case Report and Review of the Literature

Bupropion and Panic Disorder: Case Report and Review of the Literature

Pentoxifylline Inhibits Tumor Necrosis Factor Synthesis and Improves Liver Regeneration After Partial Hepatectomy in Rats by a Mechanism Related to Inhibition of TGF Beta 1 Expression

Pentoxifylline Inhibits Tumor Necrosis Factor Synthesis and Improves Liver Regeneration After Partial Hepatectomy in Rats by a Mechanism Related to Inhibition of TGF Beta 1 Expression

Targeting the tumor vascular supply with vascular disrupting agents.

Historically the role of tumor histology in the selection of treatment for lung cancer was limited to differentiation between small cell lung cancer and non-small cell lung cancer (NSCLC). More recently, the importance of tumor histology in the selection of appropriate treatment for patients with advanced stage NSCLC has been elucidated. In a randomized phase II trial of carboplatin and paclitaxel alone or with lowor high-dose bevacizumab, an increased risk of grade 3 pulmonary haemorrhage was seen in patients with squamous histology (1). As a result, these findings led to the exclusion of patients with squamous histology from phase III trials of bevacizumab in advanced stage NSCLC (2, 3). In addition to its role in reducing a specific adverse event, histological subtypes are also associated with efficacy with recent data indicating pemetrexed combined with cisplatin being more effective in patients with nonsquamous than squamous cell histology (4). Poorer survival has been reported in squamous cell histology in both treatment arms of a phase III study of chemotherapy with or without sorafenib (5) and also in patients receiving chemotherapy combined with motesanib (6). Tumor vascular supply is a major target in anti-cancer treatment and intense research efforts has resulted in a range of agents approved for clinical use. Vascular targeting strategies can be classified into several approaches including an antiangiogenic approach by targeting vascular endothelial growth factor (VEGF) and its receptors through monoclonal antibodies (bevacizumab) and tyrosine kinase inhibitors (vandetanib, sorafenib). This approach inhibits endothelial proliferation and migration, targeting new blood vessel formation of smaller, solid tumors with a major effect on the periphery of the tumor. A second method is the vascular disrupting approach. Vascular disrupting agents (VDAs) act primarily on endothelial cells and pericytes of established tumor vasculature, resulting in blood vessel occlusion, tumor ischemia and necrosis with a major effect on the central part of the tumor (7, 8). The VDAs currently in clinical development include vadimezan (ASA404), plinabulin (NPI-2358) and combretastatin A4 phosphate (CA4P). ASA404 (5,6-dimethylxanthenone-4-acetic acid or DMXAA) is a small-molecule, flavonoid tumor-vascular disrupting agent. The major mode of action of ASA404 antitumor activity is to induce the synthesis of tumor necrosis factor (TNF)-alpha. In addition, ASA404 can induce vascular endothelial cell apoptosis in tumors independently of TNF-alpha induction (9). In this issue of the Journal of Thoracic Disease, McKeage and Jameson report on a retrospective analysis of pooled data from phase II studies of ASA404 to compare safety and efficacy between squamous and non-squamous NSCLC patients (10). Data from untreated patients with advanced stage NSCLC who were randomized to receive up to carboplatin (C) and paclitaxel (P) alone or

Differential regulation of human and murine P-selectin expression and function in vivo

Leukocytes roll on P-selectin after its mobilization from secretory granules to the surfaces of platelets and endothelial cells. Tumor necrosis factor (TNF), IL-1β, and lipopolysaccharide increase synthesis of P-selectin in murine but not in human endothelial cells. To explore the physiological significance of this difference in gene regulation, we made transgenic mice bearing the human Selp gene and crossed them with mice lacking murine P-selectin (Selp(-/-)). The transgenic mice constitutively expressed human P-selectin in platelets, endothelial cells, and macrophages. P-selectin mediated comparable neutrophil migration into the inflamed peritoneum of transgenic and wild-type (WT) mice. Leukocytes rolled similarly on human or murine P-selectin on activated murine platelets and in venules of the cremaster muscle subjected to trauma. However, TNF increased murine P-selectin in venules, slowing rolling and increasing adhesion, whereas it decreased human P-selectin, accelerating rolling and decreasing adhesion. Both P- and E-selectin mediated basal rolling in the skin of WT mice, but E-selectin dominated rolling in transgenic mice. During contact hypersensitivity, murine P-selectin messenger (m) RNA was up-regulated and P-selectin was essential for leukocyte recruitment. However, human P-selectin mRNA was down-regulated and P-selectin contributed much less to leukocyte recruitment. These findings reveal functionally significant differences in basal and inducible expression of human and murine P-selectin in vivo.

Why the xanthine derivatives are used to study of P-glycoprotein-mediated multidrug resistance in L1210/VCR line cells

There is generally well known that various xanthines occur frequently in natural products, e.g. black coffee, black tea, green tea, natural dyes etc. Xanthine molecules are good tolerated and metabolised by organisms. Moreover, natural xanthines and/or sythesized xanthines may recall a lot positive affects (hemorheologic properties, anti-inflammatory properties, tracheal smooth muscle relaxant, positive chronotropic and central nervous system-stimulating, etc.) and may even induce a quantity of changes on the molecular level (inhibition of cyclic nucleotide phosphodiesterases, inhibition of the synthesis of tumor necrosis factor (TNF-alpha), cellular Ca(2+) homeostasis, etc.). In our previous paper we showed that some xanthine derivatives (pentoxifylline and its derivatives) depress P-glycoprotein (P-gp) mediated multidrug resistance of the mouse leukemic cells. Other authors, first of all Sadzuka and co-workers, confirm this usefulness of long side substituted xanthines as biochemical modulators. However, the mechanism of molecular action of xanthine derivatives has not been clarified. One of the possible ways to chemosensitize the cancer cells is direct competiting in defence mechanism - inhibition of efflux pump (P-gp). Interaction of xanthine derivatives with binding site of P-gp is a question which could be solved by experiment; although, molecular modelling may clear up this matter. But, each dynamic and static program for molecular simulation of P-gp action is dividing on input variable, considering mechanistic view of insight drug transport.

TLR4 and CD14 receptors expressed in rat pineal gland trigger NFKB pathway

Nuclear factor-kappa B (NFKB), a pivotal player in inflammatory responses, is constitutively expressed in the pineal gland. Corticosterone inhibits pineal NFKB leading to an enhancement of melatonin production, while tumor necrosis factor (TNF) leads to inhibition of Aa-nat transcription and the production of N-acetylserotonin in cultured glands. The reduction in nocturnal melatonin surge favors the mounting of the inflammatory response. Despite these data, there is no clear evidence of the ability of the pineal gland to recognize molecules that signal infection. This study investigated whether the rat pineal gland expresses receptors for lipopolysaccharide (LPS), the endotoxin from the membranes of Gram-negative bacteria, and to establish the mechanism of action of LPS. Here, we show that pineal glands possess both CD14 and toll-like receptor 4 (TLR4), membrane proteins that bind LPS and trigger the NFKB pathway. LPS induced the nuclear translocation of p50/p50 and p50/RELA dimers and the synthesis of TNF. The maximal expression of TNF in cultured glands coincides with an increase in the expression of TNF receptor 1 (TNFR1) in isolated pinealocytes. In addition, LPS inhibited the synthesis of N-acetylserotonin and melatonin. Therefore, the pineal gland transduces Gram-negative endotoxin stimulation by producing TNF and inhibiting melatonin synthesis. Here, we provide evidence to reinforce the idea of an immune-pineal axis, showing that the pineal gland is a constitutive player in the innate immune response.

Ontogenetic peculiarities of regulation of apoptosis of hypothalamic neurosecretory cells in TNF-knockout mice

Tumor necrosis factor (TNF) participates in regulation of many processes including carcinogenesis and apoptosis. However, at present, there are practically absent the works on peculiarities of regulation of apoptosis in tnf-knockout (tnf-/-) mice. These mice develop without morphological abnormalities, but they seem to have disturbances of many biological processes, such as inflammation, programmed cell death, etc. Therefore, the goal of our work was to study possible pathways of regulation of apoptosis in the absence of TNF in neurosecretory cells (NSC) of young and old mice. For this purpose, we determined immunohistochemically expression of apoptosis markers caspase-8, -9. Bax, Bcl2, Mcl1, neuropeptide vasopressin, and the apoptosis level in hypothalamus in tnf-knockout mice of different ages as compared with mice with unchanged level of TNF synthesis. It was shown that the apoptosis activation observed during aging did not depend on the tnf gene, and apoptosis at aging was caspase-dependent. It has been revealed that at aging in mouse NSC the external cell death pathway with participation of caspase-8 is activated. The pathways mediating cell death in different neurosecretory centers at aging are different. Thus, in supraoptic nucleus (SON), in all studied animal groups, animal groups, an important cause of the NSC apoptosis is Bax. In paraventricular nucleus (PVN), of the greater importance is a decrease of the antiapoptotic protection. Hence, misbalance of synthesis of proteins of the Bcl-2 family plays an important role in development of senescent apoptosis.

Microglia Protect Neurons against Ischemia by Synthesis of Tumor Necrosis Factor

Microglia and infiltrating leukocytes are considered major producers of tumor necrosis factor (TNF), which is a crucial player in cerebral ischemia and brain inflammation. We have identified a neuroprotective role for microglial-derived TNF in cerebral ischemia in mice. We show that cortical infarction and behavioral deficit are significantly exacerbated in TNF-knock-out (KO) mice compared with wild-type mice. By using in situ hybridization, immunohistochemistry, and green fluorescent protein bone marrow (BM)-chimeric mice, TNF was shown to be produced by microglia and infiltrating leukocytes. Additional analysis demonstrating that BM-chimeric TNF-KO mice grafted with wild-type BM cells developed larger infarcts than BM-chimeric wild-type mice grafted with TNF-KO BM cells provided evidence that the neuroprotective effect of TNF was attributable to microglial- not leukocyte-derived TNF. In addition, observation of increased infarction in TNF-p55 receptor (TNF-p55R)-KO mice compared with TNF-p75R and wild-type mice suggested that microglial-derived TNF exerts neuroprotective effects through TNF-p55R. We finally report that TNF deficiency is associated with reduced microglial population size and Toll-like receptor 2 expression in unmanipulated brain, which might also influence the neuronal response to injury. Our results identify microglia and microglial-derived TNF as playing a key role in determining the survival of endangered neurons in cerebral ischemia.