Intralesional injection of interferon gamma affects reactive proliferation of astrocytes in the neonatal rat brain. A preliminary study of the age-dependent effect

Following a mechanical lesion of the left cerebral hemisphere, newborn male rats received a single injection of recombinant rat interferon gamma (IFN gamma) into the lesion cavity at doses of 5, 50 and 500 U. One or two days after the injury the rats were injected with 3H-thymidine. Brain sections were immunostained for glial fibrillary acidic protein (GFAP), subjected to autoradiography and examined microscopically to record proliferating GFAP-immunopositive (GFAP+) astrocytes labeled with 3H-thymidine. Following the intermediate 50 U dose of IFN gamma, numbers of GFAP+ astrocytes and of their mitoses on day 1 after injury were significantly higher than in controls. Nevertheless, the astrocyte labeling index remained at the control level. Injections of the minimal 5 U or the maximal 500 U doses of IFN gamma had no effect on that day. On day 2, however, each of the three doses evoked a statistically significant but dose-independent reduction of the labeling index without similar changes in total number of GFAP+ astrocytes or in numbers of their divisions. The changes appear to indicate a non-linear relation between the intensity of reactive behaviour of astrocytes and the amount of IFN gamma injected into the lesion area. On the basis of previous publications, IFN gamma effects on the astrocyte reactivity are discussed as being age-dependent.     

Transplanted olfactory ensheathing cells modulate the inflammatory response in the injured spinal cord

Transplantation of olfactory ensheathing cells (OECs) into the injured spinal cord has been shown to exert neuroprotective effects and promote functional recovery. In the present study, we investigated the potential modulatory effects of OECs on the inflammatory reaction developed after photochemical injury to the spinal cord. OEC cultures were obtained from olfactory bulbs of adult Sprague-Dawley rats. Photochemical spinal cord injury was induced in adult rats at T8. Thirty minutes after the insult, either a suspension of OECs (180 000 cells in 12 microl DMEM) or DMEM alone was injected into the lesioned spinal cord.At 3, 7 and 14 days post-operation (dpo), five animals from each group were processed for histology. Double-fluorescent labeling of transverse sections of the cord were made by combination of immunohistochemistry for inflammatory markers, interleukin 1b(IL-1b) and inducible nitric oxide synthase (iNOS), and for selective markers of astrocytes (glial fibrillar acidic protein; GFAP)and microglia/macrophages (tomato lectin; LEC). Differences in the intensity and time course of glial response, and IL-1band iNOS expression were found between the two groups of rats. The reactivity grade against IL-1beta, iNOS, GFAP and LEC in OEC-transplanted rats was higher at 7 dpo and lower at 14 dpo compared with DMEM-injected rats. These results indicate that the mechanisms underlying neuroprotection by OECs might be caused by earlier, higher and shorter duration of microglia/macrophage and astrocyte responses after injury.     

Upregulation of vascular endothelial growth factor receptors Flt-1 and Flk-1 following acute spinal cord contusion in rats.

To investigate the possible role of vascular endothelial growth factor (VEGF) in the injured spinal cord, we analyzed the distribution and time course of the two tyrosine kinase receptors for VEGF, Flt-1 and Flk-1, in the rat spinal cord following contusion injury using a weight-drop impactor. The semi-quantitative RT-PCR analysis of Flt-1 and Flk-1 in the spinal cord showed slight upregulation of these receptors following spinal cord injury. Although mRNAs for Flt-1 and Flk-1 were constitutively expressed in neurons, vascular endothelial cells, and some astrocytes in laminectomy control rats, their upregulation was induced in association with microglia/macrophages and reactive astrocytes in the vicinity of the lesion within 1 day in rats with a contusion injury and persisted for at least 14 days. The spatiotemporal expression of Flt-1 in the contused spinal cord mirrored that of Flk-1 expression. In the early phase of spinal cord injury, upregulation of Flt-1 and Flk-1 mRNA occurred in microglia/macrophages that infiltrated the lesion. In addition, the expression of both receptors increased progressively in reactive astrocytes within the vicinity of the lesion, predominately in the white matter, and almost all reactive astrocytes coexpressed Flt-1 or Flk-1 and nestin. These results suggest that VEGF may be involved in the inflammatory response and the astroglial reaction to contusion injuries of the spinal cord via specific VEGF receptors.     

Cell proliferation after ischemic injury in gerbil brain

Summary Tritiated thymidine autoradiography was used to measure cellular proliferation after ischemic injury in gerbil brain. Gerbils were subjected to bilateral occlusion of the common carotid arteries which resulted in areas of necrosis, or infarcts, in the posterior thalamus or midbrain. From 12 h to 10 days following the ischemia, gerbils were injected with ³H thymidine, sacrificed 4 h later, and the brains sectioned. In order to identify astrocytes and monocytes/macrophages, immunocytochemistry was performed prior to autoradiography, using antisera against glial fibrillary acidic protein and endothelial-monocyte reticuloendothelial antigen, respectively. Immunocytochemistry was also used to visualize microvessel laminin, myelin, and leakage of serum albumin. Lastly, a histochemical procedure for acid phosphatase activity was employed to verify cellular phagocytic activity in the wound. A reproducible sequence of reactions took place during the first 10 days after ischemia. Early changes included leakage of albumin and myelin breakdown, followed by arrival of monocytes at 2 days and their differentiation into macrophages by 5 days. These cells exhibited intense proliferation from 2 to 6 days post-ischemia. Microvessel endothelial cells were maximally labeled at 4 days post-ischemia. Hypertrophied astrocytes were apparent at 2 days and proliferated from 3 to 7 days post-ischemia, and by 10 days the wound was replaced by a glial scar.     

Spinal cord injury-induced astrocyte migration and glial scar formation: effects of magnetic stimulation frequency

The effects of magnetic stimulation on spinal cord injury-induced migration of white matter astrocytes were studied using an established animal model. Ethidium bromide was injected into the dorsal spinal cord funiculus of adult Sprague-Dawley rats on the left side at T10-11. Animals then received 1.52 Tesla-pulsed magnetic stimulation for 5 min at different frequencies (0-20 Hz) for 14 consecutive days. Selected animals received the non-competitive MEK1/2 inhibitor U0126 (10 microM), prior to stimulation at 10 Hz. Lesion volumes were measured in hematoxylin/eosin-stained sections. Expression of glial fibrillary acidic protein (GFAP), microtubule associated protein-2 (MAP-2) and extra-cellular signal-regulated kinasel/2 (ERK1/2) near the epicenter of injury was examined by Western blotting with quantification using an image analysis system. Lesion volumes decreased and GFAP and p-ERK1/2 expression increased with increasing magnetic stimulation frequency (0-10 Hz). MAP-2 expression was not affected at any frequency. Pretreatment with U0126 reduced GFAP and ERK1/2 expression and increased lesion volumes in response to stimulation at 10 Hz. It is concluded that magnetic stimulation increases the migration of astrocytes to spinal cord lesions. Activation of the ERK1/2 signaling pathway is proposed to mediate astrocyte migration and glial scar formation in response to spinal cord injury.     

脑室注射白介素-1β引起的热痛敏作用

实验在SD大鼠上应用脑室微量注射和辐射热测痛的方法,研究了脑内微量注射白介素－1β对大鼠痛阈的影响。实验大鼠分为给药组和对照组,在给药组大鼠脑室注射不同剂量的白介素－1β（5、50和500pg/kg),对照组大鼠脑室注射配药液。白介素－1受体拮抗剂（IL－1ra,50ng/kg)在脑室注射白介素－1β前20min给予。实验以大鼠对光热刺激引起的缩爪反射潜伏期为痛阈指标。结果表明,脑室注射白介素－1β可显著缩短大鼠对光热刺激的缩爪反射潜伏期,并具有剂量依赖性关系。脑室给予500pg/kg的白介素－1β 20min后,大鼠对光热刺激的缩爪反射潜伏期显著缩短,40min时达峰值,然后逐渐恢复。该作用可被白介素－1β受体拮抗剂阻断。结果提示脑中白介素－1β可通过作用于白介素－1受体引起热痛敏作用。     

IL-1 gene expression in lymphoid tissues

We examined the expression of IL-1 mRNA in vivo by in situ hybridization. RNA probes for murine IL-1 alpha and IL-1 beta were used to detect IL-1 mRNA in frozen sections of spleen, lymph node, and thymus of mice injected with Salmonella typhi LPS or SRBC. No IL-1 was detected in lymphoid tissues from un-injected mice. This lack of expression correlated with the absence of IL-1 biologic activity. However, after LPS injection, IL-1 alpha and beta mRNA expression was found in macrophages of the red pulp and marginal zone of the spleen. The periarteriolar lymphoid sheath contained cells that only expressed IL-1 beta mRNA. These cells were not lymphocytes and did not stain with the macrophage marker F4/80. A similar cellular response was found after SRBC injection. Scattered macrophages in lymph nodes and thymus were positive, but only after LPS or SRBC injection. The spleens of mice injected with LPS had megakaryocytes containing IL-1 mRNA.     

Two-dimensional gel analysis of secreted proteins induced by interleukin-1 beta in rat astrocytes

Interleukin-1 beta (IL-1 beta) is a pro-inflammatory cytokine produced in the brain by endogenous microglial cells responding to injury. Levels of IL-1 beta are elevated in several neurodegenerative disorders, including Alzheimer's disease. IL-1 beta, which can act as a mitogen for astrocytes, also elicits the expression and secretion of multiple factors and paracrine 'second messengers' such as other cytokines, nerve growth factor, prostaglandins and nitric oxide that may in turn modulate neuronal and glial responses to injury. Utilizing giant, high-resolution two-dimensional gel electrophoresis, we have sought to more fully define the potential range of protein mediators that are secreted by astrocytes treated with IL-1 beta. In cultured rat astrocytes, we observe dramatic increases in the secretion of eight different protein species after 24 h of treatment with human recombinant IL-1 beta (1 U/ml). Seven of the proteins are also induced by tumor necrosis factor-alpha or basic fibroblast growth factor. Based on immunoprecipitation with specific antisera, we have identified three of these proteins as plasminogen activator inhibitor type-1, ceruloplasmin, and complement component C3. The identities of the other proteins, including the IL-1 beta-specific induction, are currently unknown. Characterization of these downstream modulators of IL-1 beta action complements gene-based approaches and will provide a better understanding of astrocyte responses to injury as well as markers for astrocyte activation in neurodegenerative diseases.     

The effect of IL-1beta on the expression of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in human chondrocytes

Interleukin-1 (IL-1) plays key roles in altering cartilage matrix turnover. This turnover is regulated by matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs). In the present study, we examined the effect of IL-1beta on cell proliferation, alkaline phosphatase (ALPase) activity, and the expression of MMPs, and TIMPs in chondrocytes derived from normal human femoral cartilage. The cells were cultured in Dulbecco's modified Eagle's medium containing 15% fetal bovine serum and 0, 1, 10, or 100 U/ml of IL-1beta for up to 28 days. The level of expression of MMPs and TIMPs was estimated by determining mRNA levels using real-time PCR and by determining protein levels using an enzyme-linked immunosorbent assay. Cell proliferation decreased in the presence of IL-1beta after day 21 of culture. ALPase activity decreased significantly in the presence of IL-1beta after day 10 of culture. The expression of MMP-1, -2, and -3 increased markedly in the presence of IL-1beta after day 21 of culture. MMP-13 expression increased markedly in the presence of IL-1beta on day 1 of culture, but decreased markedly after day 7. The expression of TIMP-1 increased significantly after day 14 of culture. The expression of TIMP-2 decreased significantly on day 1, but increased significantly from day 3 to day 14 of culture. These results suggest that IL-1beta may stimulate cartilage matrix turnover by increasing mainly MMP-13 production by the cells.     

Modulation of antibody-mediated glomerular injury in vivo by bacterial lipopolysaccharide, tumor necrosis factor, and IL-1

We have investigated the effects of LPS, human rTNF (hrTNF) and human rIL-1 beta (hrIL-1 beta) pretreatment on the intensity of antibody-mediated injury in vivo by using a passive model of anti-glomerular basement membrane (GBM) antibody-mediated nephritis in rats. The experiments show that all three pretreatments exacerbate injury in this model whether judged by albuminuria or the prevalence of glomerular capillary thrombi. The effect on albuminuria was dose dependent with all three treatments. The lowest effective dose of LPS was 0.025 microgram while those for hrTNF and hrIL-1 beta were 0.4 microgram and 0.5 microgram, respectively. All three pretreatments also increased the prevalence of glomerular capillary thrombi which were rare in rats injected with anti-GBM antibodies without pretreatment. LPS pretreatment appeared to be more effective in causing glomerular capillary thrombi than hrTNF or hrIL-1 beta and this was reflected in the correlations between albuminuria and the proportion of glomeruli with capillary thrombi. This relation was linear for all three pretreatments but the slope was appreciably greater for rats pretreated with LPS (0.37) when compared with results from rats given either hrTNF (0.22) or hrIL-1 beta (0.29). Pretreatment of nephritic rats with both cytokines increased the slope to 0.42 demonstrating a synergistic effect. The synergism of hrTNF with hrIL-1 beta was also demonstrated by the effective doses needed to induce albuminuria which was evident in rats treated with 0.05 microgram of IL-1 beta and 0.4 microgram of TNF. Neither the cytokines nor LPS caused clinical, morphologic, or biochemical evidence of renal toxicity when given alone in the dose used here but they did cause a transient increase in the number of neutrophils marginated in glomerular capillaries. Pretreatment of rats with LPS or cytokines increased the glomerular neutrophil influx after anti-GBM antibodies by roughly sixfold. Our experiments show that TNF and IL-1 can increase the severity of glomerular injury in nephritis; they may be important in modulating glomerular injury clinically.     

Expression and potential role of phospholipase D1 in cryoinjured cerebral cortex of rats

The expression and potential role of phospholipase D1 (PLD1) were studied in the cerebral cortex of rats after freeze injury. Histopathologically, cryoinjury, by exposing cerebral cortex to a prechilled rod for 1 minute, produced consistent pathological lesions, specifically neuronal death, infiltration of macrophages into the center of the cryoinjury, and reactive astrogliosis at the periphery, which caused the lesion site to become encased. Western blot analysis showed that PLD1 expression in the ipsilateral cerebral cortex increased significantly during days 1 to 3 after cryoinjury and declined slightly at post-injury day 7. PLD1 immunoreactivity was very low in the brains of sham-operated control adults. After cryoinjury, there was substantial PLD1 immunostaining of numerous inflammatory cells in the ipsilateral cortex, which were identical to ED1-positive macrophages. In addition, PLD1 immunoreactivity was increased in some neurons and astrocytes at the periphery of the cryoinjury at post-injury days 3 and 7. These findings suggest that cryoinjury by means of prechilled rods induced consistent histopathological changes in the cerebral cortex. In addition, expression of a cell activation signal, PLD1, was upregulated in macrophages and astrocytes in the ipsilateral cerebral cortex after cryoinjury.     

Intratracheally administered titanium dioxide or carbon black nanoparticles do not aggravate elastase-induced pulmonary emphysema in rats

ABSTRACT: BACKGROUND: Titanium dioxide (TiO2) and carbon black (CB) nanoparticles (NPs) have biological effects that could aggravate pulmonary emphysema. The aim of this study was to evaluate whether pulmonary administration of TiO2 or CB NPs in rats could induce and/or aggravate elastase-induced emphysema, and to investigate the underlying molecular mechanisms. METHODS: On day 1, Sprague-Dawley rats were intratracheally instilled with 25 U kg1 pancreatic porcine elastase or saline. On day 7, they received an intratracheal instillation of TiO2 or CB (at 100 and 500 mug) dispersed in bovine serum albumin or bovine serum albumin alone. Animals were sacrificed at days 8 or 21, and bronchoalveolar lavage (BAL) cellularity, histological analysis of inflammation and emphysema, and lung mRNA expression of heme oxygenase-1 (HO-1), interleukin-1beta (IL-1beta), macrophage inflammatory protein-2, monocyte chemotactic protein-1, and matrix metalloprotease (MMP)-1, and -12 were measured. In addition, pulmonary MMP-12 expression was also analyzed at the protein level by immunohistochemistry. RESULTS: TiO2 NPs per se did not modify the parameters investigated, but CB NPs increased perivascular/peribronchial infiltration, and macrophage MMP-12 expression, without inducing emphysema. Elastase administration increased BAL cellularity, histological inflammation, HO-1, IL-1beta and macrophage MMP-12 expression and induced emphysema. Exposure to TiO2 NPs did not modify pulmonary responses to elastase, but exposure to CB NPs aggravated elastase-induced histological inflammation without aggravating emphysema. CONCLUSIONS: TiO2 and CB NPs did not aggravate elastase-induced emphysema. However, CB NPs induced histological inflammation and MMP-12 mRNA and protein expression in macrophages.     

Effects of the Sigma-1 Receptor Agonist 1-(3,4-Dimethoxyphenethyl)-4-(3-Phenylpropyl)-Piperazine Dihydro-Chloride on Inflammation after Stroke

Activation of the sigma-1 receptor (Sig-1R) improves functional recovery in models of experimental stroke and is known to modulate microglia function. The present study was conducted to investigate if Sig-1R activation after experimental stroke affects mediators of the inflammatory response in the ischemic hemisphere. Male Wistar rats were subjected to transient occlusion of the middle cerebral artery (MCAO) and injected with the specific Sig-1R agonist 1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride (SA4503) or saline for 5 days starting on day 2 after MCAO. Treatment did not affect the increased levels of the pro-inflammatory cytokines interleukin 1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin 4 (IL-4), interleukin 5 (IL-5), and interleukin 13 (IL-13) in the infarct core and peri-infarct area after MCAO. In addition, treatment with SA4503 did not affect elevated levels of nitrite, TNF-α and IL-1β observed in primary cultures of microglia exposed to combined Hypoxia/Aglycemia, while the unspecific sigma receptor ligand 1,3-di-o-tolylguanidine (DTG) significantly decreased the production of nitrite and levels of TNF-α. Analysis of the ischemic hemisphere also revealed increased levels of ionized calcium binding adaptor molecule 1 (Iba1) levels in the infarct core of SA4503 treated animals. However, no difference in Iba1 immunoreactivity was detected in the infarct core. Also, levels of the proliferation marker proliferating cell nuclear antigen (PCNA) and OX-42 were not increased in the infarct core in rats treated with SA4503. Together, our results suggest that sigma-1 receptor activation affects Iba1 expression in microglia/macrophages of the ischemic hemisphere after experimental stroke but does not affect post-stroke inflammatory mediators.     

Microglia proliferation is regulated by hydrogen peroxide from NADPH oxidase

Microglia are resident brain macrophages that become activated and proliferate following brain damage or stimulation by immune mediators, such as IL-1beta or TNF-alpha. We investigated the mechanisms by which microglial proliferation is regulated in primary cultures of rat glia. We found that basal proliferation of microglia was stimulated by proinflammatory cytokines IL-1beta or TNF-alpha, and this proliferation was completely inhibited by catalase, implicating hydrogen peroxide as a mediator of proliferation. In addition, inhibitors of NADPH oxidase (diphenylene iodonium or apocynin) also prevented microglia proliferation, suggesting that this may be the source of hydrogen peroxide. IL-1beta and TNF-alpha rapidly stimulated the rate of hydrogen peroxide produced by isolated microglia, and this was inhibited by diphenylene iodonium, implying that the cytokines were acting directly on microglia to stimulate the NADPH oxidase. Low concentrations of PMA or arachidonic acid (known activators of NADPH oxidase) or xanthine/xanthine oxidase or glucose oxidase (generating hydrogen peroxide) also increased microglia proliferation and this was blocked by catalase, showing that NADPH oxidase activation or hydrogen peroxide was sufficient to stimulate microglia proliferation. In contrast to microglia, the proliferation of astrocytes was unaffected by the presence of catalase. In conclusion, these findings indicate that microglial proliferation in response to IL-1beta or TNF-alpha is mediated by hydrogen peroxide from NADPH oxidase.     

Role of TNF-alpha in prenatal alterations in dams of mice under thermal stress

The possible involvement of cytokines such as tumour necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma) that are suspected of causing pregnancy loss and miscarriage has been investigated in dams of mice subjected to hyperthermia. Thermal stress was induced by exposing mice dams at 40+/-2 degrees C for 4 h every day during the different phases of the gestation period whereas the normothermic animals were housed at 22+/-2 degrees C. The effect of maternal thermal stress was measured in pregnant mice at different phases of the gestation period namely, blastogenesis-implantation phase (days 0-5 postconceptionem [p.c.]), organogenesis or embryogenesis phase (days 6-15 p.c.) and fetogenesis phase (days 16-20 p.c.). Uterine examination of dams subjected to hyperthermia on days 6-15 p.c. showed maximum reduction in live fetus number, gestational index and maximum pre and postimplantation loss in comparison with dams housed in normothermic environment and dams exposed to thermal stress between days 0-5 and 16-20 p.c. Maximum resorption rate and number of non-viable fetuses were observed in dams exposed to hyperthermia during days 6-15 p.c. Elevated levels of TNF-alpha and IL-1 beta were observed in the amniotic fluid of dams subjected to hyperthermia during days 6-15 p.c. but IFN-gamma levels remained unaltered. Single intraperitoneal (i.p.) administration of recombinant mouse TNF-alpha at a dose of 1 and 0.5 ng/mice in dams on day 6 in normothermic condition resulted in a reduced number of live fetuses. Administration of anti-TNF-alpha antibody i.p. at a dose of 10 microg/dam on day 6 p.c. and subjected to thermal stress between days 6-15 p.c. increased marginally the number of fetuses but failed to attain statistical significance in comparison with days 6-15 p.c. thermally stressed dams without antibody treatment. It is concluded that the induction of TNF-alpha, in the amniotic fluid is associated with thermal stress during pregnancy and may be linked to the reproductive performances of dams. This study will help in understanding the mechanism of thermal injury in pregnant subjects.     

Combination of Selenium and Three Naturally Occurring Antioxidants Administration Protects d-Galactosamine-Induced Liver Injury in Rats

d-Galactosamine (d-GaIN) is a highly selective hepatotoxin that causes liver injury similar to human viral hepatitis via depletion of uridine nucleotides, which subsequently diminishes synthesis of RNA and proteins. The aim of this study was to investigate the role of selenium, ascorbic acid, beta-carotene, and alpha-tocopherol on d-GaIN-induced liver injury of rats by morphological and immunohistochemical means. In this study, Sprague–Dawley female rats were divided into four groups. Group I consists of rats injected physiologic saline solution intraperitoneally. Group II consists of rats given selenium (0.2 mg/kg per day), ascorbic acid (100 mg/kg per day), beta-carotene (15 mg/kg per day), and alpha-tocopherol (100 mg/kg per day) for 3 days via gavage method. Group III consists of the single dose of d-GaIN (500 mg/kg)-injected animals. Group IV are the d-GaIN-injected animals given the same antioxidant combination. In situ terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate nick-end labeling (TUNEL) assay was applied to determine apoptosis for paraffin sections of the liver samples. Moreover, caspase-3 and proliferating cell nuclear antigen antibody were applied for paraffin sections. In the group given d-GaIN, apoptotic cells with TUNEL assays and caspase-3 activity, which are liver injury markers induced by d-GaIN, the hepatocyte proliferation with cell proliferation assay increased. However, selenium and other three antioxidants combination clearly suppressed an increase in apoptotic cells with TUNEL assay and caspase-3 activity. In addition, it suppressed d-GaIN-induced cell proliferation in the liver. As a result, these results indicate that selenium and three naturally occurring antioxidants shows a protective effect against liver injury induced by d-GaIN. These results suggest that supplementation with the combination of selenium, ascorbic acid, beta-carotene, and alpha-tocopherol may help prevent the development of liver injury.     

Effects of repeated injections of interleukin 1beta or lipopolysaccharide on the HPA axis in the newborn rat

The hypothalamic-pituitary-adrenal (HPA) axis is stimulated during immune and inflammatory processes. Interleukin 1beta (IL-1beta) and lipopolysaccharide (LPS) are known to be potent stimulators of this axis. During postnatal development, the rat seems to be hyporesponsive to many stimuli. The effects of repeated systemic injections of IL-1beta and LPS on the HPA axis were investigated in neonatal rats. IL-1beta (0.02 microg/pup, administered twice daily from postnatal day 1 to 4) induced marked elevation in plasma corticosterone (CORT) level as compared to controls and LPS groups (0.4 microg or 1.2 microg LPS/pup, injected once daily from postnatal day 1 to 4). Adrenal wet weight was significantly higher, thymus weight was significantly lower. In contrast to the organ weights, there were no differences in CORT concentrations between LPS-exposed groups and controls. However, the weights of the adrenals in rats treated with LPS were significantly increased in a dose-dependent manner as compared to controls. The high LPS dose was associated with significantly lower thymus weights as compared to controls and 0.4 microg LPS rats. Thymus weights were significantly lower following IL-1beta- than LPS-administration. It is supposed that a developing endotoxin tolerance could account for the observed absence of CORT rise after the last LPS injection.     

Experimental study on the possibility of treatment of some hemorrhagic fevers

After intracerebral challenge with 100 PFU of Lassa virus (strain Josiah), all infected mice (CBA/calac) died (control group). Production of pro-inflammatory cytokines (IL-1beta, TNF-alpha) significantly increased in the blood of these mice during the infection. For neutralization of increasing concentrations of these cytokines recombinant IL-1RA was used intraperitonealy at a dose 100 microg kg(-1), everyday, within 5 days from the third day after the challenge. Injections of IL-1RA decreased the concentration of IL-1beta and TNF-alpha and resulted in survival of all infected mice (treatment group). Marburg fever (strain Popp) caused in guinea pigs by 5 LD(50) of virus lead to the significant increase of TNF-alpha in the animal's blood and caused a lethal outcome (control group). Treatment of infected guinea pigs by IL-1RA or anti-TNF serum decreased the concentration of TNF-alpha and resulted in survival of half of the animals (treatment group). For the treatment recombinant IL-1RA was used at a dose 100 microg kg(-1), intramuscularly, everyday, within 6 days from the third day after the challenge or anti-TNF serum, intramuscularly 0.5 ml (2000 U ml(-1); 1 U of the antiserum neutralises 0.03 ng of TNF-alpha), everyday, within 6 days from the third day after the challenge.