Immunomodulatory Effects of the Mycosporine-Like Amino Acids Shinorine and Porphyra-334.

Mycosporine-like amino acids (MAAs) are secondary metabolites, produced by a large variety of microorganisms including algae, cyanobacteria, lichen and fungi. MAAs act as UV-absorbers and photo-protectants. MAAs are suggested to exert pharmaceutical relevant bioactivities in the human system. We particularly focused on their effect on defence and regulatory pathways that are active in inflamed environments. The MAAs shinorine and porphyra-334 were isolated and purified from the red algae Porphyra sp. using chromatographic methods. The effect of MAAs on central signaling cascades, such as transcription factor nuclear factor kappa b (NF-κB) activation, as well as tryptophan metabolism, was investigated in human myelomonocytic THP-1 and THP-1-Blue cells. Cells were exposed to the MAAs in the presence or absence of lipopolysaccharide (LPS). NF-κB activity and the activity of tryptophan degrading enzyme indoleamine 2,3-dioxygenase (IDO-1) were used as readout. Compounds were tested in the concentration range from 12.5 to 200 µg/mL. Both MAAs were able to induce NF-κB activity in unstimulated THP-1-Blue cells, whereby the increase was dose-dependent and more pronounced with shinorine treatment. While shinorine also slightly superinduced NF-κB in LPS-stimulated cells, porphyra-334 reduced NF-κB activity in this inflammatory background. Modulation of tryptophan metabolism was moderate, suppressive in stimulated cells with the lower treatment concentration of both MAAs and with the unstimulated cells upon porphyra-334 treatment. Inflammatory pathways are affected by MAAs, but despite the structural similarity, diverse effects were observed.

Glyceraldehyde 3-phosphate dehydrogenase is unlikely to mediate hydrogen peroxide signaling: studies with a novel anti-dimedone sulfenic acid antibody.

Protein sulfenic acids (SOHs) are the principal oxidation products formed when redox active proteins interact with peroxide molecules. We have developed a new antibody reagent that detects protein SOHs derivatized with dimedone. Using this new antibody, we found that glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is the predominant protein sulfenate present in isolated rat ventricular myocytes under basal conditions. During oxidative stress with hydrogen peroxide (H(2)O(2)), GAPDH SOH labeling is lost, but a number of secondary dimedone-reactive protein sulfenates then appear. As the sulfenate labeling is lost, the Cys-149 sulfinic/sulfonic acid oxidation states of GAPDH appear. This hyperoxidized GAPDH is associated with both the inhibition of glycolysis and its ability to reduce H(2)O(2). We examined whether inactivation of GAPDH was causative in the generation of secondary protein sulfenates that coincide with its hyperoxidation. The selective GAPDH inhibitor koningic acid (which functions by forming a covalent adduct at Cys-149) fully prevented basal SOH labeling, as well as subsequent peroxide-induced hyperoxidation. However, koningic acid-mediated inhibition of GAPDH alone did not induce the formation of intracellular H(2)O(2) or secondary protein sulfenates and also failed to potentiate their peroxide-induced formation. Overall, GAPDH appears to have peroxidase-like properties, but its inhibition failed to impact on downstream oxidant signaling involving secondary protein sulfenation.

Reversal of resistance to cytotoxic cancer therapies: DHMEQ as a chemo-sensitizing and immuno-sensitizing agent.

The development of tumor cell resistance to conventional therapeutics is a major clinical problem. There is an urgent need to develop novel therapeutics to overcome resistance and save patients from tumor recurrences. Novel therapeutics are currently being developed based on better understanding of the underlying molecular mechanisms that govern resistance and the identification of targets that control resistance. One of the major factors that controls resistance is the transcription factor nuclear factor kappaB (NF-kappaB) that has been shown to be constitutively activated in the majority of cancers and is responsible, in large part, for tumor cell survival, growth and direct activation of anti-apoptotic gene products. The development of non-toxic inhibitors of NF-kappaB activity may result in diminishing the anti-apoptotic threshold of resistant tumor cells and leading to inhibition of tumor cell growth and cell death or sensitization to the apoptotic effects of cytotoxic therapeutics. The novel NF-kappaB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), selectively prevents the translocation of NF-kappaB into the nucleus and, hence, prevents its various transcriptional functions. Thus, DHMEQ is unlike many other NF-kappaB inhibitors that target gene products of the NF-kappaB pathway and it is also unlike proteasome inhibitors that prevent the degradation of pIkappaB. DHMEQ is a small molecule shown to be non-toxic in mice and rodents and exerts direct anti-tumor effects in vitro and in vivo as well as significant chemo- and immuno-sensitizing activities in resistant tumor cells. The present review summarizes studies that have used DHMEQ as a novel anti-cancer agent.

Display of heterologous antigens on the Bacillus subtilis spore coat using CotC as a fusion partner.

We report the use of CotC, a major component of the Bacillus subtilis spore coat, as a fusion partner for the expression of two heterologous antigens on the spore coat. Recombinant spores expressing tetanus toxin fragment C (TTFC) of Clostridium tetani or the B subunit of the heat-labile toxin of Escherichia coli (LTB) were used for oral dosing and shown to generate specific systemic and mucosal immune responses in a murine model. This report, expanding the previously described expression of TTFC on the spore surface by fusion to CotB [J Bacteriol 183 (2001) 6294] and its use for oral vaccination [Infect Immun 71 (2003) 2810] shows that different antigens can be successfully presented on the spore coat and supports the use of the spore as an efficient vehicle for mucosal immunisation.