Liver Restores Immune Homeostasis after Local Inflammation despite the Presence of Autoreactive T Cells

The liver must keep equilibrium between immune tolerance and immunity in order to protect itself from pathogens while maintaining tolerance to food antigens. An imbalance between these two states could result in an inflammatory liver disease. The aims of this study were to identify factors responsible for a break of tolerance and characterize the subsequent restoration of liver immune homeostasis. A pro-inflammatory environment was created in the liver by the co-administration of TLR ligands CpG and Poly(I:C) in presence or absence of activated liver-specific autoreactive CD8⁺ T cells. Regardless of autoreactive CD8⁺ T cells, mice injected with CpG and Poly(I:C) showed elevated serum ALT levels and a transient liver inflammation. Both CpG/Poly(I:C) and autoreactive CD8⁺T cells induced expression of TLR9 and INF-γ by the liver, and an up-regulation of homing and adhesion molecules CXCL9, CXCL10, CXCL16, ICAM-1 and VCAM-1. Transferred CFSE-labeled autoreactive CD8⁺ T cells, in presence of TLR3 and 9 ligands, were recruited by the liver and spleen and proliferated. This population then contracted by apoptosis through intrinsic and extrinsic pathways. Up-regulation of FasL and PD-L1 in the liver was observed. In conclusion, TLR-mediated activation of the innate immune system results in a pro-inflammatory environment that promotes the recruitment of lymphocytes resulting in bystander hepatitis. Despite this pro-inflammatory environment, the presence of autoreactive CD8⁺ T cells is not sufficient to sustain an autoimmune response against the liver and immune homeostasis is rapidly restored through the apoptosis of T cells.     

Vitamin B12 transport by rat liver lysosomal membrane vesicles

Vitamin B12 (hydroxycobalamin) is endocytosed by mammalian cells as a complex with transcobalamin II and then processed to free B12 in lysosomes. The mechanism by which free B12 becomes available for subsequent cellular metabolism has been uncertain. Lysosomal transport of cyanocobalamin (B12) was examined using membrane vesicles prepared from Percoll gradient purified lysosomes. B12 uptake by vesicles was dependent upon pH and was inhibited by the protonophore CCCP. Transport exhibited saturation kinetics with a Km of 3.5 microM and temperature dependence with a Q10 of 1.8. Uptake of B12 was dependent upon divalent cations and was inhibited by EDTA. Preparation of vesicles in the presence of 100 microM B12 resulted in stimulation of uptake consistent with a mechanism of countertransport. Excess cyanocobalamin, adenosylcobalamin, methylcobalamin, or cobinamide dicyanide inhibited uptake of B12. Trans-stimulation studies showed that only the first three compounds are actually transported species with cyanocobalamin as the preferred substrate. We conclude that lysosomes have a specific transport system for vitamin B12 that results in release of this enzyme cofactor to the cytoplasm.     

Vitamin E and selenium treatment of monocrotaline induced hepatotoxicity in rats

Monocrotaline (MCT) is a hepatotoxic pyrrolizidine alkaloid that is derived from plants; exposure may occur by consumption of contaminated grains, herbal teas and medicines. MCT can cause liver damage. We investigated the antioxidant effects of selenium (Se) and vitamin E against the toxic effects of MCT. Female Wistar albino rats were divided into four groups: a control group, an MCT group, an MCT + Se group, and an MCT + vitamin E group. Liver tissues were harvested, fixed, processed to paraffin and sections were cut. Anti-von Willebrand factor (vWF) immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL), and hematoxylin and eosin staining were performed. Serum and liver tissue glutathione (GSH), catalase (CAT), and glutathione peroxidase (GPx) levels were measured. Histopathological and TUNEL data showed significantly increased liver damage in the MCT group compared to controls. Histopathological and TUNEL staining indicated significant improvements in the MCT + vitamin E and MCT + Se groups compared to the MCT group. MCT significantly reduced the serum GSH level and GPx activity, and liver GPx activity. Biochemical data indicated a significant improvement in serum GSH level in the MCT + vitamin E group compared to the MCT group. We suggest that vitamin E and Se afford limited protection against MCT hepatotoxicity.     

Association of mast cells with lung function in chronic obstructive pulmonary disease

Background

Surfactant protein D (SP-D), an innate immune molecule, plays an important protective role during airway inflammation. Deficiency of this molecule induces emphysematous changes in murine lungs, but its significance in human COPD remains unclear.

Methods

We collected bronchoalveolar lavage fluid from 20 subjects with varying degrees of COPD (8 former smokers and 12 current smokers) and 15 asymptomatic healthy control subjects (5 never smokers, 3 remote former smokers, and 7 current smokers). All subjects underwent a complete medical history and pulmonary function testing. SP-D was measured by Enzyme-Linked ImmunoSorbent Assay. Statistical analysis was performed using nonparametric methods and multivariable linear regression for control of confounding. The effect of corticosteroid treatment on SP-D synthesis was studied in vitro using an established model of isolated type II alveolar epithelial cell culture.

Results

Among former smokers, those with COPD had significantly lower SP-D levels than healthy subjects (median 502 and 1067 ng/mL, respectively, p = 0.01). In a multivariable linear regression model controlling for age, sex, race, and pack-years of tobacco, COPD was independently associated with lower SP-D levels (model coefficient -539, p = 0.04) and inhaled corticosteroid use was independently associated with higher SP-D levels (398, p = 0.046). To support the hypothesis that corticosteroids increase SP-D production we used type II alveolar epithelial cells isolated from adult rat lungs. These cells responded to dexamethasone treatment by a significant increase of SP-D mRNA (p = 0.041) and protein (p = 0.037) production after 4 days of culture.

Conclusion

Among former smokers, COPD is associated with lower levels of SP-D and inhaled corticosteroid use is associated with higher levels of SP-D in the lung. Dexamethasone induced SP-D mRNA and protein expression in isolated epithelial cells in vitro. Given the importance of this molecule as a modulator of innate immunity and inflammation in the lung, low levels may play a role in the pathogenesis and/or progression of COPD. Further, we speculate that inhaled steroids may induce SP-D expression and that this mechanism may contribute to their beneficial effects in COPD. Larger, prospective studies are warranted to further elucidate the role of surfactant protein D in modulating pulmonary inflammation and COPD pathogenesis.     

Synthesis and biological evaluation of novel fluoro and iodo quinoline carboxamides as potential ligands of NK-3 receptors for in vivo imaging studies

In order to develop radioligands of human NK-3 receptor (hNK-3r) for imaging studies by positron emission tomography (PET) or single photon emission computed tomography (SPECT), a new series of fluoro- and iodo-quinoline carboxamides were synthesized and evaluated in a target receptor binding assay. Compared to the unsubstituted parent compound SB 223 412 (Ki=27 nM +/- 9), affinity was not altered for the analogues 1c and 2c bearing a fluorine in position 8 (Ki approximately 24-27 nM), and was only slightly reduced for compounds 1b, 2b, 1e and 2e fluorinated or iodinated at the position 7 (Ki approximately 49-67 nM). A drastic reduction in binding (Ki > 115 nM) was observed for all other halogenated compounds 1a, 2a, 1d, 2d, 1f and 2f.     

Do TNF-alpha-insensitive cancer cells escape alpha-tubulin nitrotyrosination?

TNF-alpha induces tumor-selective cytotoxicity in certain cancers, but many tumors are resistant to the effects of this inflammatory cytokine. This brief hypothesis outlines my views that nitric oxide-mediated alpha-tubulin posttranslational nitrotyrosination may be a major mechanism through which TNF-alpha exerts its cytotoxic effects on cancer cells. Additionally, I propose that tumor cells that are resistant to the effects of TNF-alpha may be so because of suppressed levels of "tubulin tyrosine ligase," which is responsible for the posttranslational tyrosination of alpha-tubulin.     

Synthesis and receptor binding studies of halogenated N,N-dialkylel-(2-phenyl-1H-indol-3-yl)glyoxylamides to visualize peripheral benzodiazepine receptors with SPECT or PET

A library of halogenated 2-arylindolyl-3-oxocarboxamides was prepared to develop radioligands to visualize cerebral PBR by SPECT and PET imaging. In vitro evaluation showed that most of the synthesized compounds were selective,high-affinity PBR ligands with adequate lipophilicity (log D7.4 in the range of 1.6-2.4). The iodinated derivative 11 (Ki = 2.6 nM) and the fluorinated analog 26 (Ki = 6.2 nM) displayed higher affinity than reference compounds.     

Amino acid requirement of growing pigs depending on amino acid efficiency and level of protein deposition 1st communication: lysine

In this study we investigated the influence of harvest date and genotype on the ruminai degradability of the organic matter of ensiled maize grains. Grains of the varieties Avenir, Byzance, CGS 5104 and CGS 5107 from six different harvest dates were available; they are classified as intermediate types between flint and dent com. The six harvest dates, during which time the dry matter content of the ensiled grains rose from 52% to 66%, extended from 1st September to 19th October. Assuming a passage rate of k=0.08, the effective ruminai degradability declined in this period on average from 93% to just under 79%; variety‐specific deviations also increased markedly during this period. The dry matter content (x, DM in %) of the ensiled grains had a profound influence on ruminai degradation: a highly significant curvilinear decline in ruminai degradability (y) was calculated at increasing DM levels (k = 0.08), which can be described by the equation y = ?0.072x² (±0.010)+7.417x(±1.186)?98.71(±34.58)(B=0.96;s_y,x[%]=1.36).

The ruminai degradability of ensiled maize grains is about 5–10% higher than that of fresh maize grains.