Typhoidal and non-typhoidal Salmonelleae (NTS) cause typhoid fever and gastroenteritis, respectively, in humans. Salmonella typhoid toxin contributes to typhoid disease progression and chronic infection, but little is known about the role of its NTS ortholog. We found that typhoid toxin and its NTS ortholog induce different clinical presentations. The PltB subunit of each toxin exhibits different glycan-binding preferences that correlate with glycan expression profiles of host cells targeted by each bacterium at the primary infection or intoxication sites. Through co-crystal structures of PltB subunits bound to specific glycan receptor moieties, we show that they induce markedly different glycan-binding preferences and virulence outcomes. Furthermore, immunization with the NTS S. Javiana or its toxin offers cross-reactive protection against lethal-dose typhoid toxin challenge. Cumulatively, these results offer insights into the evolution of host adaptations in Salmonella AB toxins, their cell and tissue tropisms, and the design for improved typhoid vaccines and therapeutics.

Little is known about the cellular characteristics of CD8(+) T cells in rheumatoid arthritis (RA). We addressed this by investigating whether the frequency of the CD8(+) T cell subsets and their phenotypic characteristics are altered in the peripheral blood and synovial fluid (SF) from patients with RA. In this study, CD8(+) T cells, mainly CD45RA(-) effector memory (EM) CD8(+) T cells, were increased significantly in the SF, but not in the peripheral blood from RA patients, compared with healthy controls. The synovial EM CD8(+) T cells were activated phenotypes with high levels of CD80, CD86, and PD-1, and had a proliferating signature in vivo upon Ki-67 staining, whereas the Fas-positive cells were prone to apoptosis. In addition, EM CD8(+) T cells in the SF were less cytotoxic, as they expressed less perforin and granzyme B. In particular, the proportions of synovial fluid mononuclear cells that were CCR4(+)CD8(+) T cells and IL-4-producing CD8(+) T cells (i.e., Tc2 cells) were significantly higher than those in peripheral blood mononuclear cells of patients with RA and healthy controls. In addition, the number of IL-10-producing CD8(+) suppressor T (Ts) cells increased significantly in the SF of RA patients. Especially, CD8(+) T cells were inversely correlated with disease activity. These findings strongly suggest that EM CD8(+) T cells in the SF are increased, likely because of inflammation, and they may be involved in modulating inflammation, thereby affecting the development and progression of RA.

BackgroundIntestinal epithelium is essential for maintaining normal intestinal homeostasis; its breakdown leads to chronic inflammatory pathologies, such as inflammatory bowel diseases (IBDs). Although high concentrations of S100A9 protein and interleukin-6 (IL-6) are found in patients with IBD, the expression mechanism of S100A9 in colonic epithelial cells (CECs) remains elusive. We investigated the role of IL-6 in S100A9 expression in CECs using a colitis model.MethodsIL-6 and S100A9 expression, signal transducer and activator of transcription 3 (STAT3) phosphorylation, and infiltration of immune cells were analyzed in mice with dextran sulfate sodium (DSS)-induced colitis. The effects of soluble gp130-Fc protein (sgp130Fc) and S100A9 small interfering (si) RNA (si-S100A9) on DSS-induced colitis were evaluated. The molecular mechanism of S100A9 expression was investigated in an IL-6-treated Caco-2 cell line using chromatin immunoprecipitation assays.ResultsIL-6 concentrations increased significantly in the colon tissues of DSS-treated mice. sgp130Fc or si-S100A9 administration to DSS-treated mice reduced granulocyte infiltration in CECs and induced the down-regulation of S100A9 and colitis disease activity. Treatment with STAT3 inhibitors upon IL-6 stimulation in the Caco-2 cell line demonstrated that IL-6 mediated S100A9 expression through STAT3 activation. Moreover, we found that phospho-STAT3 binds directly to the S100A9 promoter. S100A9 may recruit immune cells into inflamed colon tissues.ConclusionsElevated S100A9 expression in CECs mediated by an IL-6/STAT3 signaling cascade may play an important role in the development of colitis.

Antibiotic-resistant S. Typhi secretes typhoid toxin despite antibiotic treatment MAb targeting the receptor-binding or nuclease subunits neutralizes typhoid toxin TyTx11 makes nuclease CdtB inactive by causing catalytic-site conformational change Toxin-neutralizing epitopes identified are conserved across S. Typhi clinical isolates

Immune responses to infection or to localized injury or trauma are among the main causes of local or systemic inflammation. Despite the beneficial effect of inflammation in limiting responses to cellular and organ damage, a breakdown in the regulation of the inflammatory response may result in a wide range of chronic diseases such as arthritis, inflammatory bowel diseases, asthma and others. 1)Non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin, sulindac and indomethacin, are widely believed to have anti-inflammatory effects due to their ability to inhibit prostanoid production, and relieve inflammation by inhibiting cyclooxygenase (COX).COX are the rate-limiting enzymes that catalyze the formation of prostaglandins from arachidonic acid.2-5) Levels of prostaglandins increase early in the course of the inflammatory process. The constitutive isoform, COX-1, is expressed in most tissues predominantly in platelets, gastrointestinal tract, kidney, and liver.2-4) The inducible isoform, COX-2, is activated in response to pro-inflammatory cytokines and growth factors.3,4) Because COX-2 protein is induced by several kinds of stimuli in inflammatory cells, inhibitors of COX-2 protein induction might be candidates for the new-type NSAIDs. Also, inflammation is associated with inducible nitric oxide synthase (iNOS). Especially, nitric oxide (NO) produced by activated macrophages via iNOS was initially considered a component of innate immunity in the fight against infections. 6) It has been well accepted that nuclear-factor-kB (NF-kB) signaling pathway plays important roles in the inflammation, control of cell growth, apoptosis, stress response, and many other physiological processes. [7][8][9][10][11] There are several important molecules such as NF-kB, inhibitor kB (IkB), IKK, within NF-kB signaling pathway.12) NF-kB is a key protein in the pathway, and has been described as a major culprit and a therapeutic target in inflammation and cancer. [13][14][15][16] It is activated by lipopolysaccharide (LPS), which is a mammalian transcription factor that controls various genes that are important for immunity and inflammation.17) NF-kB is mainly composed of p50 and p65. 17) In unstimulated cells, NF-kB is present in the cytoplasm through interactions with an inhibitory protein, IkB. NF-kB is activated by IkBa degradation following phosphorylation of IkBa. 18)Platycodi Radix is the root of Platycodon grandiflorum A. DE (Campanulaceae).19) It is edible and the principal herb in Oriental medicine for diseases of the lungs and throat, and is commonly used for the inflammatory conditions of the eyes, ears, and sinuses.19) Saponins (PS) are the primary constituents of Platycodi Radix, [20][21][22] and they are responsible for diverse effects including anti-inflammation, [23][24][25][26] anti-allergy, 23) anti-tumor, 27) augmentation of immune response, [28][29][30] and stimulating the apoptosis in skin cells. 27) In the last decade, PS has generated renewed interests due to their pharmacological potentials for healing the...

Enzymes have evolved as catalysts with high degrees of stereospecificity. When both enantiomers are biologically important, enzymes with two different folds usually catalyze reactions with the individual enantiomers. In rare cases a single enzyme can process both enantiomers efficiently, but no molecular basis for such catalysis has been established. The family of bacterial chondroitin lyases ABC comprises such enzymes. They can degrade both chondroitin sulfate (CS) and dermatan sulfate (DS) glycosaminoglycans at the nonreducing end of either glucuronic acid (CS) or its epimer iduronic acid (DS) by a beta-elimination mechanism, which commences with the removal of the C-5 proton from the uronic acid. Two other structural folds evolved to perform these reactions in an epimer-specific fashion: (alpha/alpha)(5) for CS (chondroitin lyases AC) and beta-helix for DS (chondroitin lyases B); their catalytic mechanisms have been established at the molecular level. The structure of chondroitinase ABC from Proteus vulgaris showed surprising similarity to chondroitinase AC, including the presence of a Tyr-His-Glu-Arg catalytic tetrad, which provided a possible mechanism for CS degradation but not for DS degradation. We determined the structure of a distantly related Bacteroides thetaiotaomicron chondroitinase ABC to identify additional structurally conserved residues potentially involved in catalysis. We found a conserved cluster located approximately 12 A from the catalytic tetrad. We demonstrate that a histidine in this cluster is essential for catalysis of DS but not CS. The enzyme utilizes a single substrate-binding site while having two partially overlapping active sites catalyzing the respective reactions. The spatial separation of the two sets of residues suggests a substrate-induced conformational change that brings all catalytically essential residues close together.

A metagenomic fosmid library was constructed using genomic DNA isolated from the gut microflora of Hermetia illucens, a black soldier fly. A cellulase-positive clone, with the CS10 gene, was identified by extensive Congo-red overlay screenings for cellulase activity from the fosmid library of 92,000 clones. The CS10 gene was composed of a 996 bp DNA sequence encoding the mature protein of 331 amino acids. The deduced amino acids of CS10 showed 72% sequence identity with the glycosyl hydrolase family 5 gene of Dysgonomonas mossii, displaying no significant sequence homology to already known cellulases. The purified CS10 protein presented a single band of cellulase activity with a molecular mass of approximately 40 kDa on the SDS-PAGE gel and zymogram. The purified CS10 protein exhibited optimal activity at 50°C and pH 7.0, and the thermostability and pH stability of CS10 were preserved at the ranges of 20~50°C and pH 4.0~10.0. CS10 exhibited little loss of cellulase activity against various chemical reagents such as 10% polar organic solvents, 1% non-ionic detergents, and 0.5 M denaturing agents. Moreover, the substrate specificity and the product patterns by thinlayer chromatography suggested that CS10 is an endo-β-1,4-glucanase. From these biochemical properties of CS10, it is expected that the enzyme has the potential for application in industrial processes.

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