Regulatory T cell vaccination without autoantigen protects against experimental autoimmune encephalomyelitis

Regulatory T (T(reg)) cells show promise for treating autoimmune diseases, but their induction to elevated potency has been problematic when the most optimally derived cells are from diseased animals. To circumvent reliance on autoantigen-reactive T(reg) cells, stimulation to myelin-independent Ags may offer a viable alternative while maintaining potency to treat experimental autoimmune encephalomyelitis (EAE). The experimental Salmonella vaccine expressing colonization factor Ag I possesses anti-inflammatory properties and, when applied therapeutically, reduces further development of EAE in SJL mice. To ascertain T(reg) cell dependency, a kinetic analysis was performed showing increased levels of FoxP3(+)CD25(+)CD4(+) T cells. Inactivation of these T(reg) cells resulted in loss of protection. Adoptive transfer of the vaccine-induced T(reg) cells protected mice against EAE with greater potency than naive or Salmonella vector-induced T(reg) cells, and cytokine analysis revealed enhanced production of TGF-beta, not IL-10. The development of these T(reg) cells in conjunction with immune deviation by Th2 cells optimally induced protective T(reg) cells when compared those induced in the absence of Th2 cells. These data show that T(reg) cells can be induced to high potency to non-disease-inducing Ags using a bacterial vaccine.     

Loss of sialic acid binding domain redirects protein σ1 to enhance M cell-directed vaccination

Ovalbumin (OVA) genetically fused to protein sigma 1 (pσ1) results in tolerance to both OVA and pσ1. Pσ1 binds in a multi-step fashion, involving both protein- and carbohydrate-based receptors. To assess the relative pσ1 components responsible for inducing tolerance and the importance of its sialic binding domain (SABD) for immunization, modified OVA-pσ1, termed OVA-pσ1(short), was deleted of its SABD, but with its M cell targeting moiety intact, and was found to be immunostimulatory and enhanced CD4(+) and CD8(+) T cell proliferation. When used to nasally immunize mice given with and without cholera toxin (CT) adjuvant, elevated SIgA and serum IgG responses were induced, and OVA-pσ1(s) was more efficient for immunization than native OVA+CT. The immune antibodies (Abs) were derived from elevated Ab-forming cells in the upper respiratory tissues and submaxillary glands and were supported by mixed Th cell responses. Thus, these studies show that pσ1(s) can be fused to vaccines to effectively elicit improved SIgA responses.     

cDNA isolation, characterization, and protein intracellular localization of a katanin-like p60 subunit from Arabidopsis thaliana

Summary Katanin, a heterodimeric protein with ATP-dependent microtubule-severing activity, localizes to the centrosome in animal cells. Widespread occurrence is suspected as several species contain homologs to the katanin p60 subunit. Recently we isolated anArabidopsis thaliana cDNA with significant identity to the p60 subunit of sea urchin katanin. Like p60, the encoded protein is a member of the AAA superfamily of ATPases, containing the Walker ATP binding consensus and the signature AAA minimal consensus sequences within a single larger AAA/CAD amino acid motif. Phylogenetic analysis placed the encoded protein in the AAA subfamily of cytoskeleton-interactive proteins, where it formed a strongly supported clade with 4 other members identified as katanin p60 subunits. The clone was named AtKSSArabidopsis thaliana kataninlike protein small subunit). Western blots, performed using a polyclonal antibody raised against recombinant AtKSS, revealed AtKSS is present in protein extracts of all Arabidopsis organs examined. To evaluate potential interactions between AtKSS and the cytoskeleton, the intracellular localization of AtKSS was correlated with that of tubulin. AtKSS was found in perinuclear regions during interphase, surrounding the spindle poles during mitosis, but was absent from the preprophase band and phragmoplast microtubule arrays. These data support the thesis that AtKSS is an Arabidopsis homolog of the p60 subunit of katanin. Its cell cycle-dependent distribution is consistent with microtubule-severing activity, but additional studies will better define its role.