Human immunodeficiency virus type 1 Nef protein mediates neural cell death: a neurotoxic role for IP-10.
(9/4266)
HIV-1 Nef is expressed in astrocytes, but a contribution to neuropathogenesis and the development of HIV-associated dementia (HAD) remains uncertain. To determine the neuropathogenic actions of the HIV-1 Nef protein, the brain-derived (YU-2) and blood-derived (NL4-3) Nef proteins were expressed in neural cells using an alphavirus vector, which resulted in astrocyte death (P < 0.001). Supernatants from Nef-expressing astrocytes also caused neuronal death, suggesting the release of neurotoxic molecules by astrocytes. Analysis of pro-inflammatory gene induction in astrocytes expressing Nef revealed increased IP-10 mRNA expression (4000-fold) that was Nef sequence dependent. Recombinant IP-10 caused selective cell death in neurons (P < 0.001) but not astrocytes, and the cytotoxicity of supernatant from astrocytes expressing Nef YU-2 was blocked by an antibody directed against the chemokine receptor CXCR3 (P < 0.001). SCID/NOD mice implanted with a Nef YU-2-expressing vector displayed abnormal motor behavior (P < 0.05), neuroinflammation, and neuronal loss relative to controls. Analysis of mRNA levels in brains from patients with HAD also revealed increased expression of IP-10 (P < 0.05), which was confirmed by immunoreactivity detected principally in astrocytes. Phylogenetic and protein structure analyses of Nef sequences derived from HIV/AIDS patients with and without HAD suggested viral evolution toward a neurotropic Nef protein. These results indicate that HIV-1 Nef contributes to neuropathogenesis by directly causing astrocyte death together with indirect neuronal death through the cytotoxic actions of IP-10 on neurons. Furthermore, Nef molecular diversity was evident in brain tissue among patients with neurological disease and which may influence IP-10 production by astrocytes. (+info)
Design and recognition properties of a hydropathically complementary peptide to human interleukin 1 beta.
(10/4266)
A computer-designed hydropathically complementary peptide to human interleukin 1 beta (IL1 beta) precursor sequence 204-215 recognized the 204-215 peptide as well the entire IL1 beta protein with binding affinities in the micromolar range. Interaction between the complementary pair was characterized by analytical high-performance liquid affinity chromatography on columns derivatized with the computer-generated peptide. Recognition selectivity was clearly shown by the ability of the computer-generated complementary peptide columns to purify the IL1 beta-(204-215)-peptide from complex synthetic mixtures with high yields, independently of the type of solid support used. Recognition specificity was demonstrated by the inability of the IL1 beta-(204-215)-peptide and IL1 beta molecules to interact with blank columns or columns derivatized with other non-related peptides. Furthermore, scrambling the sequence of the computer-generated peptide or the IL1 beta-(204-215)-peptide in such a way as to alter their hydropathic profiles had the effect of abolishing binding. The complementary pair failed to interact in the presence of competing peptide, thus providing further evidence of specificity. Computer-generated complementary peptide affinity columns also proved useful for purification of recombinant human IL1 beta protein directly from crude Escherichia coli lysates. (+info)
Anti-inflammatory effects of extracts from some traditional Mediterranean diet plants.
(11/4266)
It is believed that bioactive compounds from plant foods may have health beneficial effects and reduce the risk of chronic inflammatory diseases. In this study extracts of 121 plants typical for the traditional Mediterranean diet have been screened for their potential anti-inflammatory activities. The ability of the extracts to inhibit cytokine-stimulated, iNOS-dependent synthesis of nitric oxide in murine endothelial cells, without affecting cell viability, was the primary indicator of their anti-inflammatory properties. Based on these experiments we selected eight plant extracts for further analysis: Chrysanthemum coronarium L., Scandix pecten-veneris L., Urospermum picroides (L.) Scop. Ex F. W. Smith, Amaranthus cf. graecizans L., Onopordum macracanthum Schousboe, Eryngium campestre L., Artemisia alba Turra and Merendera pyrenaica (Pourret) Fourn. Only the effects of Onopordum macracanthum could be non-specific since the extract strongly inhibited total protein synthesis. All remaining 7 extracts decreased nitric oxide and TNFalpha synthesis in the cells of monocyte origin activated with LPS, and 4 of them significantly reduced surface expression of VCAM1 on TNFalpha-stimulated endothelial cells. All seven plant extracts decreased cytokine or LPS-stimulated iNOS mRNA levels in both cell types. Further research to identify bioactive compounds influencing intracellular signaling pathways activated by cytokines and LPS will consequently be needed in order to better understand these in vitro effects. (+info)
The dynamics of gene expression in human lung microvascular endothelial cells after stimulation with inflammatory cytokines.
(12/4266)
Vascular endothelium plays an essential role in the pathogenesis of vasoocclusion. The changes in the endothelial cell function can be triggered by changes in gene expression caused by interaction with cytokines and blood cells. Using cDNA arrays, we have recently reported complex patterns of gene expression after stimulation of endothelial cells with TNFalpha and IL-1beta. Better understanding of the time course of gene expression changes, their concentration dependence and reversibility after withdrawal of the offending cytokine is essential for successful prevention and therapy of vasoocclusion. Here we present a detailed study of the concentration dependence and time course of gene expression in endothelial cells after their exposure to TNFalpha and IL-1beta. We focus on the adhesion molecules (VCAM-1, ICAM-1, E-selectin) and cytokines (IL-6, GCP-2, MCP-1) that are likely to contribute to vasoocclusion. We report differences in the time course and intensity of their expression and in their response to TNFalpha and IL-1beta stimulation. We demonstrate that expression of the studied genes is upregulated by low TNFalpha concentrations that better reflect the TNFalpha levels detected in the plasma of patients developing vasoocclusion. These results help to understand the changes in the endothelium and to design rational prevention and therapy of vasoocclusion. (+info)
A functional polymorphism in the IL1B gene promoter, IL1B -31C>T, is not associated with cerebral malaria in Thailand.
(13/4266)
BACKGROUND: IL-1beta and IL-1RA levels are higher in the serum of cerebral malaria patients than in patients with mild malaria. Recently, the level of IL1B expression was reported to be influenced by a polymorphism in the promoter of IL1, IL1B -31C>T. METHODS: To examine whether polymorphisms in IL1B and IL1RA influence the susceptibility to cerebral malaria, IL1B -31C>T, IL1B 3953C>T, and IL1RA variable number of tandem repeat (VNTR) were analysed in 312 Thai patients with malaria (109 cerebral malaria and 203 mild malaria patients). RESULTS: In this population, IL1B -31C>T and IL1RA VNTR were detected, while IL1B 3953C>T (i.e., IL1B 3953T) was not observed in the polymorphism screening for 32 patients. Further analyses for IL1B -31C>T and IL1RA VNTR in 110 cerebral malaria and 206 mild malaria patients showed no significant association of these polymorphisms with cerebral malaria. CONCLUSION: The present results suggest that IL1B -31C>T and IL1RA VNTR polymorphisms do not play a crucial role in susceptibility or resistance to cerebral malaria. (+info)
Time course of cytokine, corticosterone, and tissue injury responses in mice during heat strain recovery.
(14/4266)
Elevated circulating cytokines are observed in heatstroke patients, suggesting a role for these substances in the pathophysiological responses of this syndrome. Typically, cytokines are determined at end-stage heatstroke such that changes throughout progression of the syndrome are poorly understood. We hypothesized that the cytokine milieu changes during heatstroke progression, correlating with thermoregulatory, hemodynamic, and tissue injury responses to heat exposure in the mouse. We determined plasma IL-1alpha, IL-1beta, IL-2, IL-4, IL-6, IL-10, IL-12p40, IL-12p70, IFN-gamma, macrophage inflammatory protein-1alpha, TNF-alpha, corticosterone, glucose, hematocrit, and tissue injury during 24 h of recovery. Mice were exposed to ambient temperature of 39.5 +/- 0.2 degrees C, without food and water, until maximum core temperature (T(c,Max)) of 42.7 degrees C was attained. During recovery, mice displayed hypothermia (29.3 +/- 0.4 degrees C) and a feverlike elevation at 24 h (control = 36.2 +/- 0.3 degrees C vs. heat stressed = 37.8 +/- 0.3 degrees C). Dehydration ( approximately 10%) and hypoglycemia ( approximately 65-75% reduction) occurred from T(c,Max) to hypothermia. IL-1alpha, IL-2, IL-4, IL-12p70, IFN-gamma, TNF-alpha, and macrophage inflammatory protein-1alpha were undetectable. IL-12p40 was elevated at T(c,Max), whereas IL-1beta, IL-6, and IL-10 inversely correlated with core temperature, showing maximum production at hypothermia. IL-6 was elevated, whereas IL-12p40 levels were decreased below baseline at 24 h. Corticosterone positively correlated with IL-6, increasing from T(c,Max) to hypothermia, with recovery to baseline by 24 h. Tissue lesions were observed in duodenum, spleen, and kidney at T(c,Max), hypothermia, and 24 h, respectively. These data suggest that the cytokine milieu changes during heat strain recovery with similarities between findings in mice and those described for human heatstroke, supporting the application of our model to the study of cytokine responses in vivo. (+info)
Maternal CD46H*2 and IL1B-511*1 homozygosity in T helper 1-type immunity to trophoblast antigens in recurrent pregnancy loss.
(15/4266)
BACKGROUND: Women with recurrent pregnancy loss (RPL) and T-helper (Th)1-type immunity to trophoblast antigens have an increased frequency of the IL1B-511*1 promoter variant. Since CD46 gene products also regulate maternal immune responses including Th1 immunity, we investigated whether CD46 gene polymorphisms are also associated with RPL in women with and without Th1 immunity to trophoblast, and the possibility of a synergistic effect with the IL1B-511*1 promoter variant. METHODS: A case-controlled study was performed to document HindIII site polymorphism in intron 1 of the CD46 gene in 131 women with RPL and 72 fertile controls. Clinical information, Th1-type immune responsiveness to trophoblast in women with RPL history, and IL1B promoter allelotypes for this cohort were documented in a previous study. RESULTS: The frequency of the CD46H*2 allele and CD46H*2 homozygosity were significantly increased in women with RPL compared with fertile controls (P<0.028 and P<0.011). CD46H*2 homozygosity was highly associated with RPL-Th1(+) (32.4 versus 9.7% in fertile controls, P<0.0045). Logistic regression analysis revealed that women homozygous for both the IL1B-511*1 and CD46H*2 alleles had an extremely high risk of RPL-Th1(+) [exponential coefficients (EC)=24]. Among women with RPL, homozygosity at both alleles, but not each alone, significantly increased the risk of Th1 immunity to trophoblast antigens (EC=16), suggesting a possible genetic interaction between these two alleles in the development of Th1 immunity. CONCLUSIONS: The combination of homozygosity for both IL1B-511*1 and CD46H*2 alleles is a high risk factor for RPL-Th1(+). (+info)
Effects of beta-glucan obtained from the Chinese herb Astragalus membranaceus and lipopolysaccharide challenge on performance, immunological, adrenal, and somatotropic responses of weanling pigs.
(16/4266)
A total of 108 crossbred piglets (7.75 +/- 0.24 kg of BW) weaned at 28 d was used to study the interactive effects of beta-glucan obtained from the Chinese herb Astragalus membranaceus (AM) and Escherichia coli lipopolysaccharide (LPS) challenge on performance, immunological, adrenal, and somatotropic responses of weaned pigs. The treatments were in a 2 x 3 factorial arrangement; main effects were level of Astragalus membranaceus glucan (AMG; 0, 500, or 1,000 mg/kg; as-fed basis) and presence of immunological challenge (with or without LPS). The experiment included six replicate pens per treatment and three pigs per pen. Lipopolysaccharide challenges were conducted on d 7 and 21 of the trial. Blood samples were obtained from the vena cava from one pig per pen at 3 h after LPS challenge to determine plasma responses. Weight gain and feed:gain ratio were unaffected by glucan. However, there was a quadratic effect on feed intake (P < 0.05): pigs fed 500 mg of glucan/kg had the highest feed intake. Immunological challenge with LPS decreased weight gain (P = 0.02). An interaction (P = 0.01 to 0.09) between AMG and LPS was observed for glucose, IL-1beta, PGE2, and cortisol. Astragalus membranaceus glucan had a quadratic effect on the plasma concentrations of glucose, IL-1beta, PGE2, and cortisol (P < 0.05) after both LPS challenges. Plasma concentrations of glucose, IL-1beta, PGE2, and cortisol (P < 0.05) were all increased in LPS-challenged pigs compared with the control pigs after both LPS challenges. The IGF-I concentrations were less for LPS-challenged pigs than for unchallenged pigs. The lymphocyte proliferation response of peripheral blood induced by 5 microg of concanavalin A/mL (P < 0.01) and IL-2 bioactivity (P < 0.05) increased linearly with increasing addition of glucan. Pigs challenged with LPS had greater T-lymphocyte proliferation (P = 0.06) and IL-2 bioactivity (P = 0.07) than unchallenged pigs after the first immunological challenge but not after the second. In conclusion, although glucan did not improve pig performance under the conditions of the present experiment, when included at 500 mg/kg, it decreased the release of inflammatory cytokine and corticosteroid and improved the lymphocyte proliferation response of weanling piglets via enhanced IL-2 bioactivity. (+info)