Clinical correlates of DHEA associated with post-traumatic stress disorder.

OBJECTIVE: Increased plasma dehydroepiandrosterone (DHEA) and dehydroepiandrosterone-sulfate (DHEAS) have been demonstrated in post-traumatic stress disorder (PTSD), but the documented beneficial effects of these steroids in enhancing mood and cognition, as well as neuroprotection, suggest their presence in PTSD may be associated with defensive rather than maladaptive effects. METHOD: We, therefore, examined plasma DHEA, DHEAS, cortisol, and the DHEA/cortisol ratio in 40 male veterans with or without PTSD, and determined their relationships to PTSD symptom severity and symptom improvement. RESULTS: The PTSD group showed significantly higher plasma DHEA and non-significantly higher DHEAS levels as well as a significantly lower cortisol/DHEA ratio, controlling for age. Regression analyses demonstrated that DHEA and DHEAS levels could be predicted by symptom improvement and coping, whereas the cortisol/DHEA ratio was predicted by severity of childhood trauma and current symptom severity. CONCLUSION: That greater symptom improvement was related to DHEA levels may suggest for a role for these hormones in modulating recovery from PTSD.

The Tat protein of human immunodeficiency virus type 1 is a substrate and inhibitor of the interferon-induced, virally activated protein kinase, PKR.

We demonstrate that the interferon-induced, double-stranded (ds) RNA-activated kinase, PKR, is able to bind to and phosphorylate the human immunodeficiency virus type 1 (HIV-1) trans-activating protein, Tat. Furthermore, Tat can inhibit the activation and activity of the kinase. Phosphorylation of Tat by PKR is dependent on the prior activation of PKR by dsRNA and occurs on serine and threonine residues adjacent to the basic region important for TAR RNA binding and Tat function. Activated PKR efficiently phosphorylates both the two-exon form of Tat (Tat-86) and the single exon form (Tat-72). Mutagenesis indicates that the interaction between PKR and Tat requires the RNA-binding region of Tat. Tat competes with eukaryotic initiation factor 2, a well-characterized substrate of PKR, for phosphorylation by activated PKR. Tat also inhibits the autophosphorylation of PKR by dsRNA. This biochemical evidence of an intimate relationship between Tat, an important regulator of HIV transcription, and PKR, a pleiotropic cellular regulator, may provide insights into HIV-1 pathogenesis and, more generally, virus/host interactions.

Trimeric structure of human proliferating cell nuclear antigen. Implications for enzymatic function and autoantibody recognition.

The proliferating cell nuclear Ag (PCNA) is a DNA replication factor postulated to function as a sliding clamp around DNA. PCNA is also a target for autoimmunity in systemic lupus erythematosus. The autoantigenicity of PCNA is highly conformation-dependent, and reaction with most anti-PCNA sera requires a nearly full-length PCNA molecule. Here we describe the use of gel filtration and glycerol gradient sedimentation to analyze the native structure and size of PCNA. PCNA from three sources was studied (PCNA from HeLa cells, PCNA purified after its overexpression in bacteria, and PCNA produced in the wheat germ cell-free translation system) as well as mutant forms of PCNA translated in vitro. In each case, full-length PCNA behaved as a trimer. Analysis of mutant proteins revealed a correlation between the trimeric form and binding to the common type of human anti-PCNA autoantibody, suggesting that the Abs are specific for the active form of the protein. These findings are consistent with the idea that autoantibodies are generated as a response to native Ag and provide experimental support for the hypothesis that PCNA serves its processive function in DNA replication as a trimeric ring structure.

Autoreactive epitope profiles of the proliferating cell nuclear antigen define two classes of autoantibodies.

The proliferating cell nuclear antigen (PCNA) is a conserved protein required for cellular DNA replication. PCNA was first recognized using serum from the autoimmune disease SLE. To analyze the regions on PCNA that confer autoantibody binding, we modified the cDNA encoding full-length PCNA to generate a series of amino terminal, carboxyl terminal and internally deleted constructs, which were transcribed and then translated in vitro using the wheat germ cell-free translation system. An immunoprecipitation assay was used to study the ability of these mutated forms of PCNA to bind anti-PCNA Abs from patients with SLE. Eight of the ten sera studied required a protein of nearly full length for binding: antigenicity was abrogated by removal of 39 amino acids from the amino terminus, by various internal deletions, or by the removal of 15 (but not 11) amino acids from the carboxyl terminus. The remaining two sera exhibited an Ab-binding specificity to the carboxyl-terminally truncated proteins similar to that of the majority of anti-PCNA sera, but their specificity was different in the amino terminus: these sera were able to recognize PCNA lacking over 40% of sequence in the amino terminus, but they did not bind proteins with short internal deletions in that region. Thus, these epitopes appear to be conformational and distinguish two classes of autoimmune sera.

Antibody to a 63 kilodalton insect protein in ankylosing spondylitis.

Ankylosing spondylitis (AS) is associated with antibodies to a heat shock puff on drosophila chromosomes. This observation was investigated by immunoblotting using extracts of the Schneider insect cell line and HeLa cells, before and after heat shock. An insect protein of 63 kilodaltons (but no equivalent human protein) was recognised by 21 (46%) of 46 serum samples from patients with AS, one of two patients with Reiter's syndrome, four (7%) of 60 patients with systemic lupus erythematosus, and two (4%) of 50 control subjects, but not by serum samples from patients with rheumatoid arthritis (RA). Previous heat shock did not appear to affect the strength of reaction, but ML-30, a monoclonal antibody to the mycobacterial 65 kilodalton heat shock protein (hsp65), also recognised an insect protein of 63 kilodaltons by immunoblotting. Antibodies to recombinant mycobacterial hsp65 were measured by enzyme linked immunosorbent assay (ELISA) in serum samples from patients with AS and RA. IgA binding to hsp65 was increased in 41% of AS and 19% of RA serum samples, but there was no correlation with detection of antibody to the insect 63 kilodalton protein.