66 research outputs found
Genetic basis for variation in plasma IL-18 levels in persons with chronic hepatitis C virus and human immunodeficiency virus-1 infections
Inflammasomes are multi-protein complexes integrating pathogen-triggered signaling leading to the generation of pro-inflammatory cytokines including interleukin-18 (IL-18). Hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections are associated with elevated IL-18, suggesting inflammasome activation. However, there is marked person-to-person variation in the inflammasome response to HCV and HIV. We hypothesized that host genetics may explain this variation. To test this, we analyzed the associations of plasma IL-18 levels and polymorphisms in 10 genes in the inflammasome cascade. About 1538 participants with active HIV and/or HCV infection in three ancestry groups are included. Samples were genotyped using the Illumina Omni 1-quad and Omni 2.5 arrays. Linear regression analyses were performed to test the association of variants with log IL-18 including HCV and HIV infection status, and HIV RNA in each ancestry group and then meta-analyzed. Eleven highly correlated single-nucleotide polymorphisms (rΒ²=0.98β1) in the IL-18-BCO2 region were significantly associated with log IL-18; each T allele of rs80011693 confers a decrease of 0.06 log pgβmlβ»ΒΉ of IL-18 after adjusting for covariates (rs80011693; rs111311302 Ξ²=β0.06, P-value=2.7 Γ 10β»β΄). In conclusion, genetic variation in IL-18 is associated with IL-18 production in response to HIV and HCV infection, and may explain variability in the inflammatory outcomes of chronic viral infections
A system for accurate and automated injection of hyperpolarized substrate with minimal dead time and scalable volumes over a large range
Over recent years hyperpolarization by dissolution dynamic nuclear polarization has become an established
technique for studying metabolism in vivo in animal models. Temporal signal plots obtained from
the injected metabolite and daughter products, e.g. pyruvate and lactate, can be fitted to compartmental
models to estimate kinetic rate constants. Modeling and physiological parameter estimation can be made
more robust by consistent and reproducible injections through automation. An injection system previously
developed by us was limited in the injectable volume to between 0.6 and 2.4 ml and injection
was delayed due to a required syringe filling step. An improved MR-compatible injector system has been
developed that measures the pH of injected substrate, uses flow control to reduce dead volume within the
injection cannula and can be operated over a larger volume range. The delay time to injection has been
minimized by removing the syringe filling step by use of a peristaltic pump. For 100 ll to 10.000 ml, the
volume range typically used for mice to rabbits, the average delivered volume was 97.8% of the demand
volume. The standard deviation of delivered volumes was 7 ll for 100 ll and 20 ll for 10.000 ml demand
volumes (mean S.D. was 9 ul in this range). In three repeat injections through a fixed 0.96 mm O.D. tube
the coefficient of variation for the area under the curve was 2%. For in vivo injections of hyperpolarized
pyruvate in tumor-bearing rats, signal was first detected in the input femoral vein cannula at 3β4 s
post-injection trigger signal and at 9β12 s in tumor tissue. The pH of the injected pyruvate was
7.1 Β± 0.3 (mean Β± S.D., n = 10). For small injection volumes, e.g. less than 100 ll, the internal diameter
of the tubing contained within the peristaltic pump could be reduced to improve accuracy. Larger injection
volumes are limited only by the size of the receiving vessel connected to the pump
Granulocytes mediates the Fas-L-associated apoptosis during lung metastasis of melanoma that determines the metastatic behaviour
The survival of tumour cells in a new tissue environment is crucial for tumour metastasis. Factors contributing to the death of tumour cells during metastasis are not completely understood. In murine melanoma model, activation of Fas (CD95, APO-1) signal in tumour cells reduces their lung metastasis potential, which may be associated with an induction of apoptosis in tumours. To elucidate the cellular mechanism, we used a Fas-ligand (Fas-L) specific ribozyme (Fas-Lribozyme) to suppress the expression of Fas-L but not Fas or TNF-Ξ± in B16F10 melanoma cells. The Fas-Lribozyme-carrying cells grew slightly faster in vitro with better viability than controls. Suppression of Fas-L in B16F10 melanoma cells by Fas-Lribozyme enhanced lung metastasis of the cells in C57BL/6 mice, and that was correlated with reductions in both apoptotic tumour cells and granulocytic infiltration. Mice depleted of granulocytes, but not CD4+ and CD8+ cells, showed a greatly elevated susceptibility to lung metastasis. Moreover, apoptosis in tumour cells was significantly reduced in granulocyte-depleted mice during the course of tumour formation. Taken together, our findings indicate that Fas-L-associated apoptosis in tumour cells determines the metastasis behaviour of melanoma in the lung and this apoptosis is primarily mediated by the cytotoxicity of recruited granulocytes
Safety and Immunogenicity of an HIV-1 Gag DNA Vaccine with or without IL-12 and/or IL-15 Plasmid Cytokine Adjuvant in Healthy, HIV-1 Uninfected Adults
DNA vaccines are a promising approach to vaccination since they circumvent the problem of vector-induced immunity. DNA plasmid cytokine adjuvants have been shown to augment immune responses in small animals and in macaques.We performed two first in human HIV vaccine trials in the US, Brazil and Thailand of an RNA-optimized truncated HIV-1 gag gene (p37) DNA derived from strain HXB2 administered either alone or in combination with dose-escalation of IL-12 or IL-15 plasmid cytokine adjuvants. Vaccinations with both the HIV immunogen and cytokine adjuvant were generally well-tolerated and no significant vaccine-related adverse events were identified. A small number of subjects developed asymptomatic low titer antibodies to IL-12 or IL-15. Cellular immunogenicity following 3 and 4 vaccinations was poor, with response rates to gag of 4.9%/8.7% among vaccinees receiving gag DNA alone, 0%/11.5% among those receiving gag DNA+IL-15, and no responders among those receiving DNA+high dose (1500 ug) IL-12 DNA. However, after three doses, 44.4% (4/9) of vaccinees receiving gag DNA and intermediate dose (500 ug) of IL-12 DNA demonstrated a detectable cellular immune response.This combination of HIV gag DNA with plasmid cytokine adjuvants was well tolerated. There were minimal responses to HIV gag DNA alone, and no apparent augmentation with either IL-12 or IL-15 plasmid cytokine adjuvants. Despite the promise of DNA vaccines, newer formulations or methods of delivery will be required to increase their immunogenicity.Clinicaltrials.gov NCT00115960 NCT00111605
Design principles for inflammasome inhibition by pyrin-only-proteins
Inflammasomes are filamentous signaling platforms essential for host defense against various intracellular calamities such as pathogen invasion and genotoxic stresses. However, dysregulated inflammasomes cause an array of human diseases including autoinflammatory disorders and cancer. It was recently identified that endogenous pyrin-only-proteins (POPs) regulate inflammasomes by directly inhibiting their filament assembly. Here, by combining Rosetta in silico, in vitro, and in cellulo methods, we investigate the target specificity and inhibition mechanisms of POPs. We find here that POP1 is ineffective in directly inhibiting the central inflammasome adaptor ASC. Instead, POP1 acts as a decoy and targets the assembly of upstream receptor pyrin-domain (PYD) filaments such as those of AIM2, IFI16, NLRP3, and NLRP6. Moreover, not only does POP2 directly suppress the nucleation of ASC, but it can also inhibit the elongation of receptor filaments. In addition to inhibiting the elongation of AIM2 and NLRP6 filaments, POP3 potently suppresses the nucleation of ASC. Our Rosetta analyses and biochemical experiments consistently suggest that a combination of favorable and unfavorable interactions between POPs and PYDs is necessary for effective recognition and inhibition. Together, we reveal the intrinsic target redundancy of POPs and their inhibitory mechanisms
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