CpG motifs present in bacteria DNA rapidly induce lymphocytes to secrete interleukin 6, interleukin 12, and interferon gamma.

Abstract

Bacterial infection stimulates the host to mount a rapid inflammatory response. A 6-base DNA motif consisting of an unmethylated CpG dinucleotide flanked by two 5' purines and two 3' pyrimidines was shown to contribute to this response by inducing polyclonal B-cell (3,4,(7)(8)(9)11). Recent work from our laboratory suggested that this B-cell stimulation was mediated by a 6-base nt motif consisting of an unmethylated CpG dinucleotide flanked by two 5' purines and two 3' pyrimidines (12). This motif is expressed nearly 20 times more frequently in bacterial than vertebrate DNA (12)(13)(14).In addition to B-cell activation, the innate immune response to bacterial infection is characterized by the production of immunomodulatory cytokines (15,16). These include interleukin (IL) 6, which contributes to T-and B-cell activation (17-20), IFN-y, which (25)(26)(27).The concentration of cytokine in culture supernatants was determined by using a modification of the assay system described above. Supernatants were serially diluted in PBS/1% bovine serum albumin and incubated on anti-cytokine-coated microtiter plates for 2 hr. Biotinylated anti-cytokine antibody followed by avidin-conjugated alkaline phosphatase were used in a colorimetric assay to detect the presence of bound cytokine (27).Cell Purification. Mononuclear cells were incubated with biotinylated anti-CD4, anti-CD8, anti-CD11, anti-CD14, or

Influence of stimulatory and suppressive DNA motifs on host susceptibility to inflammatory arthritis

“…In vivo and ex vivo studies have shown that systemic delivery of CpG DNA stimulates immune cells to secrete a variety of proinflammatory chemokines and cytokines (7,15,16). To determine whether such treatment increases host susceptibility to arthritis, BALB/c mice were injected IP with 300 g of CpG DNA.…”

“…Unmethylated CpG motifs in bacterial DNA trigger an immune response characterized by the production of proinflammatory and Th1 cytokines (6)(7)(8)(9). This evolutionarily conserved response can protect the host from infectious pathogens (18)(19)(20), but it also increases the risk of developing autoimmune and inflammatory diseases (4,(21)(22)(23)(24).…”

“…Blinded histologic evaluation of joints 4 days after injection of CpG ODNs or bacterial DNA provides rigorous evidence of pathology, which correlates with joint swelling (Pearson's correlation coefficient r ϭ 0.59, P Ͻ 0.0001) (5). Although systemically administered CpG DNA stimulates B cells, natural killer cells, and dendritic cells to proliferate, mature, and/or secrete in vivo (6)(7)(8)(9), no direct effect on the joints has ever been reported (Table 1) (4). The findings of the present study demonstrate that the generalized immune activation triggered by systemic CpG ODN treatment increases host susceptibility to a subsequent arthritogenic stimulus.…”

“…Numerous studies have shown that CpG DNA has immunostimulatory properties, triggering immune cells to proliferate, mature, and secrete a variety of proinflammatory chemokines and cytokines (6)(7)(8)(9). This immune activation can be inhibited by "suppressive" ODNs, which block the production of Th1 and proinflammatory cytokines (10)(11)(12)(13).…”

Adaptive and innate immune responses to gene transfer vectors: role of cytokines and chemokines in vector function

“…Bacterial DNA is a powerful stimulator of polyclonal proliferation in B cells and cytokine production by monocytes and lymphocytes. 20,21 These properties are attributed to unmethylated CpG motifs present in plasmid DNA or synthetic oligonucleotides, motifs which are much less frequent in mammalian DNA, which is not immunostimulatory. 22 These responses are sensitive to inhibitors of endosomal acidification, which is coupled to the generation of intracellular reactive oxygen species and the degradation of IkB.…”