An endogenous nanomineral chaperones luminal antigen and peptidoglycan to intestinal immune cells.

In humans and other mammals it is known that calcium and phosphate ions are secreted from the distal small intestine into the lumen. However, why this secretion occurs is unclear. Here, we show that the process leads to the formation of amorphous magnesium-substituted calcium phosphate nanoparticles that trap soluble macromolecules, such as bacterial peptidoglycan and orally fed protein antigens, in the lumen and transport them to immune cells of the intestinal tissue. The macromolecule-containing nanoparticles utilize epithelial M cells to enter Peyer's patches, small areas of the intestine concentrated with particle-scavenging immune cells. In wild-type mice, intestinal immune cells containing these naturally formed nanoparticles expressed the immune tolerance-associated molecule 'programmed death-ligand 1', whereas in NOD1/2 double knockout mice, which cannot recognize peptidoglycan, programmed death-ligand 1 was undetected. Our results explain a role for constitutively formed calcium phosphate nanoparticles in the gut lumen and show how this helps to shape intestinal immune homeostasis

Assessment of Integration-defective HIV-1 and EIAV Vectors In Vitro and In Vivo

The interest in integrase-defective lentiviral vectors (IDLVs) stems from their potential advantage of large cloning capacity and broad cell tropism while avoiding the possibility of insertional mutagenesis. Here, we directly compared the transducing potential of IDLVs based on the equine infectious anemia virus (EIAV) to the more commonly described HIV-1 IDLVs. IDLVs were constructed by introducing equivalent single/triple mutations into the integrase catalytic triad. We show that both the single and the triple mutant HIV-1 IDLVs transduce the PC12 cells, but not the C2C12 cells, with similar efficiency to their parental HIV-1 vector. In contrast, the single and triple EIAV IDLVs did not efficiently transduce either differentiated cell line. Moreover, this HIV-1 IDLV-mediated expression was independent of any residual integration activity because reporter expression was lost when cell cycling was restored. Four weeks following stereotactic administration into adult rat brains, only the single HIV-1 IDLV mutant displayed a comparable transduction profile to the parental HIV-1 vector. In contrast, neither EIAV IDLV mutants showed significant reporter gene expression. This work indicates that the transducing potential of IDLVs appears to depend not only on the choice of integrase mutation and type of target cell, but also on the nature of the lentiviral vector

Related IgA1 and IgG producing cells in blood and diseased mucosa in ulcerative colitis

Background: Ulcerative colitis (UC) is a chronic inflammatory bowel disease in which the colonic mucosa is infiltrated with plasma cells producing IgG autoantibodies. It is not known whether this represents a local mucosal response which has switched to IgG or a peripheral response which may have been initiated by peripheral antigen which homed to the colonic mucosa. The clonal distribution of IgG secreting cells and isotype switched variants in UC is not known. Aims: To investigate the clonal distribution of mucosal IgG in UC and to search for related IgG and IgA secreting cells in normal and diseased mucosa and blood in UC. To investigate characteristics which may discriminate between the mucosal and peripheral repertoire in the normal mucosa and in UC. Patients: Blood and normal and diseased mucosa from two patients with UC were studied. Methods: Immunoglobulin gene analysis and clone specific polymerase chain reaction were used to study the clonal distribution and characteristics of IgG and related IgA in the mucosa and blood of patients with UC. Results: The IgG response in the mucosa of UC patients included widespread clones of cells that were present in both the diseased mucosa and blood but that were scarce in normal mucosa. Clonally related IgA class switch variants, all IgA1, were detected but also only in the diseased mucosa and blood. This suggests that these clones home preferentially to the diseased mucosa. We showed that J(H)1 usage was characteristic of the peripheral repertoire, and that examples of J(H)1 usage were observed in mucosal IgG in UC. Conclusions: Overall, these data are consistent with a model of UC in which a peripheral response is expressed and expanded in the colonic mucosa