Manipulating DNA damage-response signaling for the treatment of immune-mediated diseases.

Antigen-activated lymphocytes undergo extraordinarily rapid cell division in the course of immune responses. We hypothesized that this unique aspect of lymphocyte biology leads to unusual genomic stress in recently antigen-activated lymphocytes and that targeted manipulation of DNA damage-response (DDR) signaling pathways would allow for selective therapeutic targeting of pathological T cells in disease contexts. Consistent with these hypotheses, we found that activated mouse and human T cells display a pronounced DDR in vitro and in vivo.

Single Amino Acid Polymorphisms of Pertussis Toxin Subunit S2 (PtxB) Affect Protein Function.

Whooping cough due to Bordetella pertussis is increasing in incidence, in part due to accumulation of mutations which increase bacterial fitness in highly vaccinated populations. Polymorphisms in the pertussis toxin, ptxA and ptxB genes, and the pertactin, prn genes of clinical isolates of Bordetella pertussis collected in Cincinnati from 1989 through 2005 were examined. While the ptxA and prn genotypes were variable, all 48 strains had the ptxB2 genotype; ptxB1 encodes glycine at amino acid 18 of the S2 subunit of pertussis toxin, while ptxB2 encodes serine.

Etoposide selectively ablates activated T cells to control the immunoregulatory disorder hemophagocytic lymphohistiocytosis.

Hemophagocytic lymphohistiocytosis (HLH) is an inborn disorder of immune regulation caused by mutations affecting perforin-dependent cytotoxicity. Defects in this pathway impair negative feedback between cytotoxic lymphocytes and APCs, leading to prolonged and pathologic activation of T cells. Etoposide, a widely used chemotherapeutic drug that inhibits topoisomerase II, is the mainstay of treatment for HLH, although its therapeutic mechanism remains unknown.

Pertussis toxin B-pentamer mediates intercellular transfer of membrane proteins and lipids.

Pertussis toxin (PTx) is the major virulence factor of Bordetella pertussis. The enzymatic or active (A) subunit inactivates host G protein coupled receptor (GPCR) signaling pathways. The non-enzymatic binding (B) subunit also mediates biological effects due to lectin-like binding characteristics, including the induction of T cell receptor (TCR) signaling and subsequent down-regulation of chemokine receptor expression.

Mechanistic insight into pertussis toxin and lectin signaling using T cells engineered to express a CD8α/CD3ζ chimeric receptor.

Mammalian cell-surface receptors typically display N- or O-linked glycans added post-translationally. Plant lectins such as phytohemagluttinin (PHA) can activate the T cell receptor (TCR) and other cell-surface receptors by binding to glycans and initiating receptor cross-linking. Pathogenic microorganisms such as Bordetella pertussis also express proteins with lectin-like activities.

Identification and characterization of the carbohydrate ligands recognized by pertussis toxin via a glycan microarray and surface plasmon resonance.

Binding of pertussis toxin (PTx) was examined by a glycan microarray; 53 positive hits fell into four general groups. One group represents sialylated biantennary compounds with an N-glycan core terminating in alpha2-6-linked sialic acid. The second group consists of multiantennary compounds with a canonical N-glycan core, but lacking terminal sialic acids, which represents a departure from the previous understanding of PTx binding to N-glycans.

Acellular pertussis vaccines and complement killing of Bordetella pertussis.

Antibody-dependent complement killing of Bordetella pertussis after immunization with a three-component acellular pertussis vaccine was characterized. Postimmunization activity was unchanged for about half of the adult vaccine recipients. The responses of the other individuals were complex, with evidence of both beneficial and antagonistic responses occurring, sometimes in the same individual.

Antibody-mediated neutralization of pertussis toxin-induced mitogenicity of human peripheral blood mononuclear cells.

Antibody-mediated neutralization of pertussis toxin-induced proliferation of human peripheral blood mononuclear cells (PBMC) was assessed using alamarBlue and compared with results from the Chinese hamster ovary (CHO) cell assay using sera from vaccinated adults and convalescent children. Neutralization values for the CHO assay were similar for vaccinated and convalescent subjects; however. the convalescent group had higher titers in the PBMC assay.