Shigella deploy multiple countermeasures against host innate immune responses

Although the intestinal epithelium is equipped with multiple defense systems that sense bacterial components, transmit alarms to the immune system, clear the bacteria, and renew the injured epithelial lining, mucosal bacterial pathogens are capable of efficiently colonizing the intestinal epithelium, because they have evolved systems that modulate the inflammatory and immune responses of the host and exploit the harmful environments as replicative niches. In this review we highlight current topics concerning Shigella's tactics that interfere with the innate immune systems.     

Inactivation of TNF-α ameliorates diabetic neuropathy in mice

Tumor necrosis factor (TNF)-α is a potent proinflammatory cytokine involved in the pathogenesis of diabetic neuropathy. We inactivated TNF-α to determine if it is a valid therapeutic target for the treatment of diabetic neuropathy. We effected the inactivation in diabetic neuropathy using two approaches: by genetic inactivation of TNF-α (TNF-α(-/-) mice) or by neutralization of TNF-α protein using the monoclonal antibody infliximab. We induced diabetes using streptozotocin in wild-type and TNF-α(-/-) mice. We measured serum TNF-α concentration and the level of TNF-α mRNA in the dorsal root ganglion (DRG) and evaluated nerve function by a combination of motor (MNCV) and sensory (SNCV) nerve conduction velocities and tail flick test, as well as cytological analysis of intraepidermal nerve fiber density (IENFD) and immunostaining of DRG for NF-κB p65 serine-276 phosphorylated and cleaved caspase-3. Compared with nondiabetic mice, TNF-α(+/+) diabetic mice displayed significant impairments of MNCV, SNCV, tail flick test, and IENFD as well as increased expression of NF-κB p65 and cleaved caspase-3 in their DRG. In contrast, although nondiabetic TNF-α(-/-) mice showed mild abnormalities of IENFD under basal conditions, diabetic TNF-α(-/-) mice showed no evidence of abnormal nerve function tests compared with nondiabetic mice. A single injection of infliximab in diabetic TNF-α(+/+) mice led to suppression of the increased serum TNF-α and amelioration of the electrophysiological and biochemical deficits for at least 4 wk. Moreover, the increased TNF-α mRNA expression in diabetic DRG was also attenuated by infliximab, suggesting infliximab's effects may involve the local suppression of TNF-α. Infliximab, an agent currently in clinical use, is effective in targeting TNF-α action and expression and amelioration of diabetic neuropathy in mice.     

Hepatitis C Related Chronic Liver Cirrhosis: Feasibility of Texture Analysis of MR Images for Classification of Fibrosis Stage and Necroinflammatory Activity Grade

Purpose

To assess the feasibility of texture analysis for classifying fibrosis stage and necroinflammatory activity grade in patients with chronic hepatitis C on T2-weighted (T2W), T1-weighted (T1W) and Gd-EOB-DTPA-enhanced hepatocyte-phase (EOB-HP) imaging.

Materials and methods

From April 2008 to June 2012, MR images from 123 patients with pathologically proven chronic hepatitis C were retrospectively analyzed. Texture parameters derived from histogram, gradient, run-length matrix, co-occurrence matrix, autoregressive model and wavelet transform methods were estimated with imaging software. Fisher, probability of classification error and average correlation, and mutual information coefficients were used to extract subsets of optimized texture features. Linear discriminant analysis in combination with 1-nearest neighbor classifier (LDA/1-NN) was used for lesion classification. In compliance with the software requirement, classification was performed based on datasets from all patients, the patient group with necroinflammatory activity grade 1, and that with fibrosis stage 4, respectively.

Results

Based on all patient dataset, LDA/1-NN produced misclassification rates of 28.46%, 35.77% and 20.33% for fibrosis staging and 34.15%, 25.20% and 28.46% for necroinflammatory activity grading in T2W, T1W and EOB-HP images. In the patient group with necroinflammatory activity grade 1, LDA/1-NN yielded misclassification rates of 5.00%, 0% and 12.50% for fibrosis staging in T2W, T1W and EOB-HP images respectively. In the patient group with fibrosis stage 4, LDA/1-NN yielded misclassification rates of 5.88%, 12.94% and 11.76% for necroinflammatory activity grading in T2W, T1W and EOB-HP images respectively.

Conclusion

Texture quantitative parameters of MR images facilitate classification of the fibrosis stage as well as necroinflammatory activity grade in chronic hepatitis C, especially after categorizing the input dataset according to the activity or fibrosis degree in order to remove the interference between the fibrosis stage and necroinflammatory activity grade on texture features.     

Magnesium deficiency suppresses cell cycle progression mediated by increase in transcriptional activity of p21(Cip1) and p27(Kip1) in renal epithelial NRK-52E cells

Lack of magnesium suppresses cell growth, but the molecular mechanism is not examined in detail. We examined the effect of extracellular magnesium deficiency on cell cycle progression and the expression of cell cycle regulators in renal epithelial NRK-52E cells. In synchronized cells caused by serum-starved method, over 80% cells were distributed in G1 phase. Cell proliferation and percentage of the cells in S phase in the presence of MgCl(2) were higher than those in the absence of MgCl(2) , suggesting that magnesium is involved in the cell cycle progression from G1 to S phase. After serum addition, the expression levels of p21(Cip1) and p27(Kip1) in the absence of MgCl(2) were higher than those in the presence of MgCl(2) . The exogenous expression of p21(Cip1) or p27(Kip1) increased the percentage in G1 phase, whereas it decreased that in S phase. The mRNA levels and promoter activities of p21(Cip1) and p27(Kip1) in the absence of MgCl(2) were higher than those in the presence of MgCl(2) . The phosphorylated p53 (p-p53) level was decreased by MgCl(2) addition. Pifithrin-α, a p53 inhibitor, decreased the p-p53, p21(Cip1) and p27(Kip1) levels, and the percentage in G1 phase in the absence of MgCl(2) . Rotenone, a mitochondrial respiratory inhibitor, decreased ATP content and increased the p-p53 level in the presence of MgCl(2) . Together, lack of magnesium may increase p21(Cip1) and p27(Kip1) levels mediated by the decrease in ATP content and the activation of p53, resulting in the suppression of cell cycle progression from G1 to S phase in NRK-52E cells.     

Novel FAD-dependent glucose dehydrogenase for a dioxygen-insensitive glucose biosensor

A novel FAD-dependent glucose dehydrogenase (FAD-GDH) was found and its enzymatic property for glucose sensing was characterized. FAD-GDH oxidized glucose in the presence of some artificial electron acceptors, except for O2, and exhibited thermostability, high substrate specificity and a large Michaelis constant for glucose. FAD-GDH was applied to an amperometric glucose sensor with Fe(CN)6(3-) as a soluble mediator. The use of a relatively high concentration of Fe(CN)6(3-) resulted in a good linearity between the current response and the glucose concentration, taking into account a large Michaelis constant for Fe(CN)6(3-). The glucose sensor was completely insensitive to O2 and responded linearly to glucose up to 30 mM. Compared to glucose, the response to other saccharides was negligible. The sensor can be stored at room temperature in a desiccator for at least one month without any change in the response or activity.     

Rat organic solute carrier protein 1 (rOscp1) mediated the transport of organic solutes in Xenopus laevis oocytes: isolation and pharmacological characterization of rOscp1

Rat organic solute carrier protein 1 (rOscp1) was isolated from a rat testis cDNA library. Isolated rOscp1 cDNA consisted of 1089 base pairs that encoded a 363-amino acid protein, and the amino acid sequence was 88% and 93% identical to that of human OSCP1 (hOSCP1) and mouse Oscp1 (mOscp1), respectively. The message for rOscp1 is highly detected in rat testis. When expressed in X. oocytes, rOscp1 mediated the high affinity transport of p-aminohippurate (PAH) with a Km value of 15.7+/-1.9 microM, and rOscp1-mediated organic solutes were exhibited in time- and Na+-independent manners. rOscp1 also transported various structurally heterogenous compounds such as testosterone, dehydroepiandrosterone sulfate (DHEA-S), and taurocholate with some differences in substrate specificity compared with hOSCP1. Immunohistochemical analysis revealed that the rOscp1 protein is localized in the basal membrane side of Sertoli cells as observed in mouse testis [Kobayashi et al., 2007; Kobayashi, Y., Tsuchiya, A., Hayashi, T., Kohyama, N., Ohbayashi, M., Yamamoto, T., 2007. Isolation and characterization of polyspecific mouse organic solute carrier protein 1 (mOscp1). Drug Metabolism and Disposition 35 (7), 1239-1245]. Thus, the present results indicate that a newly isolated cDNA clone, rOscp1, is a polyspecific organic solute carrier protein with some differences in substrate specificity compared with human and mouse OSCP1.