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Biomedical subjects

D S Pisetsky

Publications and source records attributed to D S Pisetsky.

At least 37 records · Page 2Linked to original sources
PubMed2001

Immune response to DNA in systemic lupus erythematosus.

Antibodies to DNA occur prominently in systemic lupus erythematosus and have been extensively studied as probes for underlying immune disturbances. These antibodies have features of DNA antigen drive. While previous models for this response posited DNA as simple and inert, recent studies have indicated that DNA is immunologically diverse and, depending upon sequence and backbone structure, can stimulate or suppress immune responses. In particular, bacterial DNA is immunologically potent and can function as both an adjuvant and immunogen, eliciting in normal individuals antibodies to sites exclusive to bacterial DNA. In mice genetically predisposed to autoimmunity, however, bacterial DNA can elicit anti-DNA autoantibodies under conditions in which mammalian DNA is inactive. These findings suggest that foreign DNA can serve as a trigger for anti-DNA responses, with SLE reflecting a disturbance in antibody specificity and a shift from binding of sequential to backbone determinants. In contrast to bacterial DNA, mammalian DNA can suppress certain immune responses and prevent macrophage cytokine production. To the extent that self-DNA drives responses in SLE, anti-DNA production in this disease may reflect a failure of this suppression. The recognition of DNA's immune activities thus suggests novel possibilities for disease pathogenesis.

Animals↗
PubMed2000

The role of cell surface receptors in the activation of human B cells by phosphorothioate oligonucleotides.

Phosphorothioate oligodeoxynucleotides (sODN) containing the CpG motif or TCG repeats induce T cell-independent polyclonal activation of human B cells. To elucidate the mechanism of this response, the role of cell surface receptors was investigated. Sepharose beads coated with stimulatory but not nonstimulatory sODNs induced B cell proliferation comparably with soluble sODNs. The B cell stimulatory activity of Sepharose-bound sODN did not result from free sODN released from the beads since media incubated with coated beads were inactive. Using FITC-labeled sODNs as probes, binding to human B cells could be detected by flow cytometry. Binding was rapid, saturable, initially temperature independent, but with a rapid off-rate. Competition studies indicated that both stimulatory sODNs and minimally stimulatory sODNs bound to the same receptor. By contrast, phosphodiester oligonucleotides with the same nucleotide sequence as sODNs and bacterial DNA inhibited the binding of sODNs to B cells minimally. Charge appeared to contribute to the binding of sODNs to B cells since binding of sODNs was competitively inhibited by negatively charged molecules, including fucoidan, poly I, and polyvinyl sulfate. These data indicate that human B cells bind sODNs by a receptor-mediated mechanism that is necessary but not sufficient for polyclonal activation.

Adult↗
PubMed2000

Stimulation of thymocyte proliferation by phosphorothioate DNA oligonucleotides.

DNA is a complex macromolecule the immunological properties of which depend on short sequence motifs called CpG motifs or immunostimulatory sequences (ISS). These sequences are mitogenic for B cells and can stimulate macrophage cytokine production. While these sequences do not directly activate T cells, they can augment effects of stimulation via the TCR. Furthermore, ISS can affect T cells because of macrophage production of IL-12 and IFN-alpha/beta. In these studies, we further evaluated the immune effects of DNA on T cells, testing the possibility that certain T cell populations can respond directly to this stimulus. We therefore tested the in vitro responses of thymocytes to a series of phosphodiester (Po) and phosphorothioate (Ps) oligonucleotides (ODNs) varying in sequence. In in vitro cultures, phosphorothioate ODNs (sODNs) containing CpG motifs induced significant proliferation of murine thymocytes, although phosphodiester compounds lacked activity. The magnitude of stimulation varied with sequences flanking the CpG motifs, as both dA and dT sequences enhanced the stimulatory capacity of the CpG motif. Furthermore, CpG sODNs were strong costimulators of anti-CD3-mediated thymocyte activation, increasing proliferation compared to anti-CD3 in the absence of DNA. This activation was only partially inhibited by cyclosporine A and was not dependent on a calcium influx. Together, these results indicate that phosphorothioate oligonucleotides containing CpG motifs can directly induce thymocyte proliferation as well as augment TCR activation. These observations thus extend the range of actions of CpG DNA and suggest additional mechanisms for its function as an immunomodulatory agent or adjuvant.

Adjuvants, Immunologic↗
PubMed2000

Inhibition of murine macrophage IL-12 production by natural and synthetic DNA.

DNA is a complex macromolecule whose immunological properties vary with sequence and structure. To determine whether DNA can inhibit immune responses, the effects of mammalian DNA and synthetic phosphodiester (Po) and phosphorothioate (Ps) oligonucleotides (ODNs) on IL-12 production were tested using murine macrophages. With bacterial DNA as a stimulant, calf thymus DNA and human placenta DNA blocked IL-12 production by splenic and bone marrow macrophages. A (dG)(30) Po ODN and all single-base Ps 30 mer ODNs were also effective inhibitors. The Ps ODNs also blocked IL-12 production induced by lipopolysaccharide (LPS) and a stimulatory Ps ODN. With the J774 cell line, single-base Ps ODNs inhibited IL-12 production induced by bacterial DNA, LPS, and a stimulatory Ps ODN. Together, these results indicate that DNA has inhibitory properties, suggesting that mammalian DNA could limit immune activation during inflammation and counteract the effects of bacterial DNA.

Adjuvants, Immunologic↗
PubMed2000

The role of bacterial DNA in autoantibody induction.

Bacterial DNA has potent immunological properties that can stimulate the immune system in SLE in both specific and non-specific ways. As such, this molecule may play an important role in disease pathogenesis, because it can exert immunomodulatory activity and function as a molecular mimic. Future studies will hopefully both determine the role of foreign nucleic acids in the induction of autoantibodies and lead to strategies for their elimination.

Animals↗
PubMed2000

Anti-DNA and autoantibodies.

Systemic lupus erythematosus is a prototypic autoimmune disease characterized by antinuclear antibodies (ANAs), including pathogenic specificities to DNA. As shown by recent research, ANA production is a genetically determined process in which self antigens drive B and T cells that have escaped the normal mechanisms of tolerance. Although antibodies can bind isolated protein or nucleic acid species, the in vivo driving antigens likely exist as complexes that have been released from apoptotic cells. The clinical measurement of ANAs, although valuable in assessing diagnosis and prognosis, must nevertheless be interpreted with caution because ANAs, despite their disease associations, can occur in healthy individuals.

Animals↗
PubMed2000

Immune responses to DNA in normal and aberrant immunity.

Because of structural microheterogeneity, DNA can exert powerful effects that lead to immune system activation as well as antibody induction. These activating effects resemble those ofendotoxin and result from sequences that occur much more commonly in bacterial DNA than in mammalian DNA. In contrast, mammalian DNA can inhibit the response to bacterial DNA as well as other stimuli and may serve a counterregulatory role during infection. The recognition of the immune effects of DNA is relevant to the pathogenesis of a variety of infectious and inflammatory diseases including systemic lupus erythematosus, a prototypic autoimmune disease characterized by anti-DNA autoantibodies.

Adjuvants, Immunologic↗
PubMed1999

Influence of backbone chemistry on immune activation by synthetic oligonucleotides.

Depending on base sequence, DNA displays immunological activities relevant to the design of novel therapeutic agents. To determine the influence of backbone structure on these activities, we tested a series of synthetic phosphodiester and phosphorothioate oligonucleotides in in vitro cultures of murine spleen cells. These compounds were 30 bases long and consisted of either a single base or an immunostimulatory sequence (AACGTT) flanked on 5' and 3' ends by 12 nucleotides of each base. Cell activation was assessed by both thymidine incorporation and expression of cell surface CD69; production of interleukin-6 and interleukin-12 was used as a measure of cytokine stimulation. In these assays, phosphorothioate oligonucleotides induced much higher levels of proliferation, CD69 expression, and cytokine production than the comparable phosphodiester compounds and had activity at lower concentrations. The sequence for optimal stimulation by phosphorothioates varied among responses, however. For example, whereas compounds containing an immunostimulatory sequence all induced similar levels of proliferation and CD69 expression, cytokine production was greatest with compounds with dA and dT flanks. Furthermore, while single base dG oligonucleotides stimulated proliferation as both phosphodiesters and phosphorothioates, they failed to stimulate cytokine production. Together, these findings indicate that base sequence as well as backbone chemistry influence immune activation by synthetic oligonucleotides, with the effects varying among responses. While suggesting differences in the structure-function relationships of nucleic acids in their immune activities, these findings also raise the possibility of the design of agents with specific patterns of immune modulation.

Animals↗
PubMed1999

Deficiency of 5-lipoxygenase abolishes sex-related survival differences in MRL-lpr/lpr mice.

Leukotrienes, the 5-lipoxygenase (5LO) products of arachidonic acid metabolism, have many proinflammatory actions that have been implicated in the pathogenesis of a variety of inflammatory diseases. To investigate the role of LTs in autoimmune disease, we generated an MRL-lpr/lpr mouse line with a targeted disruption of the 5lo gene. MRL-lpr/lpr mice spontaneously develop autoimmune disease that has many features resembling human systemic lupus erythematosus, including sex-related survival differences; female MRL-lpr/lpr mice experience significant early mortality compared with males. Unexpectedly, we found that mortality was accelerated in male 5LO-deficient MRL-lpr/lpr mice compared with male wild-type MRL-lpr/lpr animals. In contrast, the 5lo mutation had no effect on survival in females. Mortality was also accelerated in male MRL-lpr/lpr mice that were treated chronically with a pharmacological inhibitor of LT synthesis. Furthermore, LT-dependent inflammatory responses are enhanced in male MRL-lpr/lpr mice compared with females, and the 5lo mutation has greater impact on these responses in males. Because immune complex-mediated glomerulonephritis is the major cause of death in MRL-lpr/lpr mice and has been related to arachidonic acid metabolites, we also assessed kidney function and histopathology. In male MRL-lpr/lpr mice, renal plasma flow was significantly reduced in the 5lo-/- compared with the 5lo+/+ group, although there were no differences in the severity of renal histopathology, lymphoid hyperplasia, or arthritis between the groups. These findings suggest that the presence of a functional 5lo gene confers a survival advantage on male MRL-lpr/lpr mice and that, when 5LO function is inhibited, either genetically or pharmacologically, this advantage is abolished.

Acute Disease↗
PubMed1999

The influence of base sequence on the immunostimulatory properties of DNA.

DNA is a complex macromolecule whose immunological properties vary with base sequences. As shown with synthetic oligonucleotides, potent immune stimulation results from six base motifs called CpG motifs or immunostimulatory sequences (ISS). These sequences center on an unmethylated CpG dinucleotide and occur much more commonly in bacterial DNA than mammalian DNA. As such, CpG motifs may function as a danger signal to stimulate B cell activation and cytokine production. In addition to CpG motifs, runs of deoxyguanosine (dG) residues in DNA can induce B cell activation and promote macrophage cytokine expression by adjacent CpG motifs. The array of these sequences may determine the overall immune activity of a DNA molecule and affect such processes as host defense against infection as well as the use of plasmids and synthetic oligonucleotides to treat disease.

Animals↗
PubMed1999

Immunostimulatory properties of genomic DNA from different bacterial species.

Bacterial DNA has potent immunological properties because of its content of immunostimulatory sequences centering on CpG motifs. To investigate whether DNA from various bacterial species differ in these properties, the activity of a panel of DNA was assessed in in vitro cultures of murine spleen cells. This panel varied in base composition and included DNA from Clostridium perfringens (CP), Escherichia coli (EC), Micrococcus lysodeikticus (MC), Staphylococcus aureus (SA), and, as a mammalian DNA control, calf thymus (CT) DNA. In assays of IL-12 and IFN-gamma production as well as B cell mitogenesis, these DNA showed marked differences in their immunostimulatory activity. For both cytokine and B cell responses, EC DNA demonstrated the highest activity while CP DNA had the lowest activity among the bacterial DNA. To determine whether differences in stimulatory capacity resulted from differences in cell uptake, the activity of DNA complexed with lipofectin was tested. While the addition of lipofectin to DNA increased stimulation by all DNA, it did not change the relative potency of the DNA tested. These results indicate that bacterial DNA differ in their immunostimulatory capacity, most likely reflecting their content of CpG motifs. These differences could affect the induction of innate immunity as well as the consequences of infection.

Animals↗
PubMed1999

Pain in the rheumatic diseases. Practical aspects of diagnosis and treatment.

Patients with rheumatic disease experience pain that can be intense, persistent, and disabling. This pain is frequently multifactorial in origin and has both central and peripheral components. Because of the array of conditions that can cause musculoskeletal pain, patient management must begin with a complete clinical assessment that identifies possible etiologies and measures objective findings against subjective complaints. Especially in patients with known rheumatic disease, the possibility of concurrent pain of central origin must be considered and appropriate treatment given. By applying a comprehensive therapy plan of drugs, physical therapy, and patient education, significant benefits can often be achieved in this prevalent group of painful diseases.

Arthritis, Rheumatoid↗
PubMed1999

The influence of DNA size on the binding of antibodies to DNA in the sera of normal human subjects and patients with systemic lupus erythematosus (SLE).

To elucidate antibody recognition of DNA in normal and aberrant immunity, the binding of sera of normal human subjects (NHS) and patients with SLE was tested with mammalian and bacterial DNA varying in size. Klebsiella pneumoniae (KP) and calf thymus (CT) single-stranded DNA (ssDNA) were investigated as model antigens using the restriction enzyme HinfI to generate fragments with the size range of 800-5000 base pairs. The influence of size on activity was assessed by ELISA by both titration of serum as well as coating antigen concentration. In both assay formats, SLE sera bound equivalently to intact CT and KP DNA, but had dramatically reduced reactivity to fragments of both antigens. In contrast, NHS bound similarly to intact KP DNA and its fragments but had low reactivity to CT DNA. These results suggest that SLE and NHS anti-DNA react with different antigenic determinants on DNA, as shown by cross-reactivity as well as size dependency in solid-phase assays.

Antibodies, Antinuclear↗