Parasite-Derived Plasma Microparticles Contribute Significantly to Malaria Infection-Induced Inflammation through Potent Macrophage Stimulation

There is considerable debate as to the nature of the primary parasite-derived moieties that activate innate pro-inflammatory responses during malaria infection. Microparticles (MPs), which are produced by numerous cell types following vesiculation of the cellular membrane as a consequence of cell death or immune-activation, exert strong pro-inflammatory activity in other disease states. Here we demonstrate that MPs, derived from the plasma of malaria infected mice, but not naive mice, induce potent activation of macrophages in vitro as measured by CD40 up-regulation and TNF production. In vitro, these MPs induced significantly higher levels of macrophage activation than intact infected red blood cells. Immunofluorescence staining revealed that MPs contained significant amounts of parasite material indicating that they are derived primarily from infected red blood cells rather than platelets or endothelial cells. MP driven macrophage activation was completely abolished in the absence of MyD88 and TLR-4 signalling. Similar levels of immunogenic MPs were produced in WT and in TNF^−/−, IFN-γ^−/−, IL-12^−/− and RAG-1^−/− malaria-infected mice, but were not produced in mice injected with LPS, showing that inflammation is not required for the production of MPs during malaria infection. This study therefore establishes parasitized red blood cell-derived MPs as a major inducer of systemic inflammation during malaria infection, raising important questions about their role in severe disease and in the generation of adaptive immune responses.     

Effects of homologous ghrelins on the growth hormone/insulin-like growth factor-I axis in the tilapia, Oreochromis mossambicus

Ghrelin is a gut-brain peptide synthesized mainly in the oxyntic mucosal cells of the stomach, and has potent growth hormone (GH)-releasing and orexigenic activities. Recently, two forms of ghrelin, ghrelin-C8 and -C10, were identified in the Mozambique tilapia (Oreochromis mossambicus). The present study describes in vitro and in vivo effects of these endogenous ghrelins on the GH/insulin-like growth factor-I (IGF-I) axis. Ghrelin-C8 (100 nM) stimulated GH release from primary cultures of pituitary cells after 4 and 8 h of incubation, whereas no effect was seen on prolactin (PRL) release. Stimulatory effects of ghrelin-C8 and -C10 (100 nM) on GH release during 6 h of incubation were blocked by pre-incubation with GHS receptor antagonist, [D-Lys(3)]-GHRP-6 (10 microM). Intraperitoneal injection of ghrelin-C8 (1 ng/g body weight) and -C10 (0.1 and 1 ng/g body weight) significantly increased plasma GH levels after 5 h. Significant increases were observed also in hepatic expression of IGF-I and GH receptor (GHR) mRNA following injections of both forms of ghrelin (0.1 and 1 ng/g body weight), although there was no effect on plasma levels of IGF-I. In the next experiment, both forms of ghrelin (1 ng/g body weight) significantly increased plasma IGF-I levels 10 h after the injection. No significant effect of either ghrelin was observed on plasma PRL levels. Both forms of GHS receptor (GHSR-1a and -1b) were found in the pituitary, clearly indicating that tilapia ghrelins stimulate primarily GH release through the GHS receptor. Stimulation of hepatic expression of IGF-I and GHR suggests metabolic roles of ghrelin in tilapia.     

Crh1p and Crh2p are required for the cross-linking of chitin to beta(1-6)glucan in the Saccharomyces cerevisiae cell wall

In budding yeast, chitin is found in three locations: at the primary septum, largely in free form, at the mother-bud neck, partially linked to beta(1-3)glucan, and in the lateral wall, attached in part to beta(1-6)glucan. By using a recently developed strategy for the study of cell wall cross-links, we have found that chitin linked to beta(1-6)glucan is diminished in mutants of the CRH1 or the CRH2/UTR2 gene and completely absent in a double mutant. This indicates that Crh1p and Crh2p, homologues of glycosyltransferases, ferry chitin chains from chitin synthase III to beta(1-6)glucan. Deletion of CRH1 and/or CRH2 aggravated the defects of fks1Delta and gas1Delta mutants, which are impaired in cell wall synthesis. A temperature shift from 30 degrees C to 38 degrees C increased the proportion of chitin attached to beta(1-6)glucan. The expression of CRH1, but not that of CRH2, was also higher at 38 degrees C in a manner dependent on the cell integrity pathway. Furthermore, the localization of both Crh1p and Crh2p at the cell cortex, the area where the chitin-beta(1-6)glucan complex is found, was greatly enhanced at 38 degrees C. Crh1p and Crh2p are the first proteins directly implicated in the formation of cross-links between cell wall components in fungi.     

Tiludronate treatment improves structural changes and symptoms of osteoarthritis in the canine anterior cruciate ligament model

Introduction

The aim of this prospective, randomized, controlled, double-blind study was to evaluate the effects of tiludronate (TLN), a bisphosphonate, on structural, biochemical and molecular changes and function in an experimental dog model of osteoarthritis (OA).

Methods

Baseline values were established the week preceding surgical transection of the right cranial/anterior cruciate ligament, with eight dogs serving as OA placebo controls and eight others receiving four TLN injections (2 mg/kg subcutaneously) at two-week intervals starting the day of surgery for eight weeks. At baseline, Week 4 and Week 8, the functional outcome was evaluated using kinetic gait analysis, telemetered locomotor actimetry and video-automated behaviour capture. Pain impairment was assessed using a composite numerical rating scale (NRS), a visual analog scale, and electrodermal activity (EDA). At necropsy (Week 8), macroscopic and histomorphological analyses of synovium, cartilage and subchondral bone of the femoral condyles and tibial plateaus were assessed. Immunohistochemistry of cartilage (matrix metalloproteinase (MMP)-1, MMP-13, and a disintegrin and metalloproteinase domain with thrombospondin motifs (ADAMTS5)) and subchondral bone (cathepsin K) was performed. Synovial fluid was analyzed for inflammatory (PGE₂ and nitrite/nitrate levels) biomarkers. Statistical analyses (mixed and generalized linear models) were performed with an α-threshold of 0.05.

Results

A better functional outcome was observed in TLN dogs than OA placebo controls. Hence, TLN dogs had lower gait disability (P = 0.04 at Week 8) and NRS score (P = 0.03, group effect), and demonstrated behaviours of painless condition with the video-capture (P < 0.04). Dogs treated with TLN demonstrated a trend toward improved actimetry and less pain according to EDA. Macroscopically, both groups had similar level of morphometric lesions, TLN-treated dogs having less joint effusion (P = 0.01), reduced synovial fluid levels of PGE₂ (P = 0.02), nitrites/nitrates (P = 0.01), lower synovitis score (P < 0.01) and a greater subchondral bone surface (P < 0.01). Immunohistochemical staining revealed lower levels in TLN-treated dogs of MMP-13 (P = 0.02), ADAMTS5 (P = 0.02) in cartilage and cathepsin K (P = 0.02) in subchondral bone.

Conclusion

Tiludronate treatment demonstrated a positive effect on gait disability and joint symptoms. This is likely related to the positive influence of the treatment at improving some OA structural changes and reducing the synthesis of catabolic and inflammatory mediators.     

A genetic code Boolean structure. I. The meaning of Boolean deductions

This paper proposes a genetic code Boolean structure derived from hydrogen bond numbers and chemical types of bases, purines and pyrimidines. It shows that in such Boolean structure, deductions comprise physico-chemical meaning. In particular, codons with adenine as a second base coding to hydrophilic amino acids are not deductible from codons with uracil in the same position, which code to hydrophobic amino acids. Boolean deductions could help us describe the gene evolution process. For instance, most of the reported mutations that confer drug resistance to the HIV protease gene correspond to deductions. What is more, in the human beta-globin gene a similar situation appears where most of the single codon mutations correspond to Boolean deductions from the respective wild-type codon.