Nigella sativa (Black Cumin) Seed Extract Alleviates Symptoms of Allergic Diarrhea in Mice, Involving Opioid Receptors

The incidence of food hypersensitivity and food allergies is on the rise and new treatment approaches are needed. We investigated whether N. sativa, one of its components, thymoquinone, or synthetic opioid receptor (OR)-agonists can alleviate food allergy. Hence, ovalbumin (OVA) -sensitized BALB/c-mice were pre-treated either with a hexanic N. sativa seed extract, thymoquinone, kappa- (U50'4889) or mu-OR-agonists (DAMGO) and subsequently challenged intra-gastrically with OVA. All 4 treatments significantly decreased clinical scores of OVA-induced diarrhea. N. sativa seed extract, thymoquinone, and U50'488 also decreased intestinal mast cell numbers and plasma mouse mast cell protease-1 (MMCP-1). DAMGO, in contrast, had no effect on mast cell parameters but decreased IFNγ, IL-4, IL-5, and IL-10 concentration after ex vivo re-stimulation of mesenteric lymphocytes. The effects on allergy symptoms were reversible by OR-antagonist pre-treatment, whereas most of the effects on immunological parameter were not. We demonstrate that N. sativa seed extract significantly improves symptoms and immune parameters in murine OVA-induced allergic diarrhea; this effect is at least partially mediated by thymoquinone. ORs may also be involved and could be a new target for intestinal allergy symptom alleviation. N. sativa seed extract seems to be a promising candidate for nutritional interventions in humans with food allergy

Structural Basis of the Chromodomain of Cbx3 Bound to Methylated Peptides from Histone H1 and G9a

HP1 proteins are highly conserved heterochromatin proteins, which have been identified to be structural adapters assembling a variety of macromolecular complexes involved in regulation of gene expression, chromatin remodeling and heterochromatin formation. Much evidence shows that HP1 proteins interact with numerous proteins including methylated histones, histone methyltransferases and so on. Cbx3 is one of the paralogues of HP1 proteins, which has been reported to specifically recognize trimethylated histone H3K9 mark, and a consensus binding motif has been defined for the Cbx3 chromodomain.Here, we found that the Cbx3 chromodomain can bind to H1K26me2 and G9aK185me3 with comparable binding affinities compared to H3K9me3. We also determined the crystal structures of the human Cbx3 chromodomain in complex with dimethylated histone H1K26 and trimethylated G9aK185 peptides, respectively. The complex structures unveil that the Cbx3 chromodomain specifically bind methylated histone H1K26 and G9aK185 through a conserved mechanism.The Cbx3 chromodomain binds with comparable affinities to all of the methylated H3K9, H1K26 and G9aK185 peptides. It is suggested that Cbx3 may regulate gene expression via recognizing both histones and non-histone proteins