Cortisol induction by poly ICLC: implications for clinical trials of interferon

Broad-spectrum drugs against viral agents

Development of antivirals has focused primarily on vaccines and on treatments for specific viral agents. Although effective, these approaches may be limited in situations where the etiologic agent is unknown or when the target virus has undergone mutation, recombination or reassortment. Augmentation of the innate immune response may be an effective alternative for disease amelioration. Nonspecific, broad-spectrum immune responses can be induced by double-stranded (ds)RNAs such as poly (ICLC), or oligonucleotides (ODNs) containing unmethylated deocycytidyl-deoxyguanosinyl (CpG) motifs. These may offer protection against various bacterial and viral pathogens regardless of their genetic makeup, zoonotic origin or drug resistance.

Effects of cytokines on the pituitary-adrenal axis in cancer patients

Cytokines, which include interferons (IFNs), interleukins (ILs), and tumor necrosis factor (TNF), are immunoregulatory proteins produced by lymphocytes and inflammatory cells. Several cytokines, most noteworthy IFNs and ILs, stimulate glucocorticoid secretion. In this study, the effects of variable doses and repetitive administration of IFNs and TNF on secretion of pituitary hormones and cortisol were measured. Patients were given for a period of 15 days on alternating days injections of IFN-beta (IFN-beta ser), 90 or 450 x 10(6) IU, IFN-gamma, 0.1-100 x 10(6) IU, or TNF 125-275 micrograms/m2. Sixty to 120 min after IFN-beta ser injection median levels of cortisol, adrenocorticotropin (ACTH), prolactin (PRL), and growth hormone (GH) rose two-fold. Urinary free cortisol excretion increased significantly during the day following IFN-beta ser administration. IFN-gamma > or = 30 x 10(6) IU caused a comparable rise in plasma cortisol. TNF induced two- to four-fold increases in ACTH and cortisol. The fact that increased cortisol secretion was associated with a rise in the level of ACTH as well as PRL and GH suggests that the cytokines increased cortisol by stimulating the anterior pituitary. The hormonal response induced by cytokines was unrelated to their pyrogenic effect, undiminished with repetitive treatment, and not dose-dependent above a threshold level. These observations reinforce the concept of a physiologic link between the immune system and the hypothalamic-pituitary-adrenal (HPA) axis.

Clinical trials of interferons in multiple sclerosis. What have we learned?

Although multiple sclerosis (MS) is generally believed to be an immune-mediated disease, conventional therapy with ACTH, corticosteroids, or immunosuppressive drugs is unsatisfactory. Aside from their unpredictable therapeutic effects, these agents are potentially hazardous and can only be given for short periods of time. There is an urgent need for less toxic yet effective immunotherapy, that that can be administered early in the disease and continued indefinitely. Clinical trials of the interferons (IFNs) have not only led to a promising new approach to treatment, but have also stimulated basic research in the immunological mechanisms of underlying disease activity. Administration of IFN-gamma promotes exacerbations of MS, whereas recombinant IFN-beta has been shown, in controlled clinical trials, to suppress them. Other ongoing studies are likely to provide further information about its long-term therapeutic value. More importantly, laboratory studies performed in conjunction with these clinical trials have provided fresh insights into the pathogenesis of MS by revealing immunoregulatory mechanisms in which endogenous IFN-gamma, TNF-alpha, and other cytokines appear to play central roles. The 'Decade of the Brain' may therefore see answers both to the therapeutic dilemma of MS, and to more basic questions about the function of IFNs and other cytokines in activation and regulation of the disease process.

Abnormal in vitro proliferation and differentiation of T cell colony-forming cells in patients with tropical spastic paraparesis/human T lymphocyte virus type I (HTLV-I)-associated myeloencephalopathy and healthy HTLV-I carriers

T cell colonies were generated from the peripheral blood mononuclear cells (PBMC) of 10 patients with tropical spastic paraparesis/human T lymphocyte virus type I (HTLV-I)-associated myeloencephalopathy (TSP/HAM), two healthy HTLV-I carriers, and 17 healthy HTLV-I-seronegative subjects. PBMC were cultured in methylcellulose in the absence of added growth factors (spontaneous T cell colonies), or in the presence of phorbol myristate acetate and interleukin 2 (induced T cell colonies). PBMC T cell colony-forming cells (T-CFC) from all TSP/HAM patients and HTLV-I carriers were able to grow in the absence of added growth factors and/or mitogenic stimulation. Pooled spontaneous and induced colonies were composed of cells bearing CD3+, CD4+, CD8+, and CD1+ antigens. Colonies from normal HTLV-I-seronegative subjects displayed mature cells bearing the CD3+, CD4+, CD8+, and CD1- surface phenotype. In addition, spontaneous and induced T cell colonies expressed HTLV-I antigens in 18-38% of the cells from TSP/HAM patients and HTLV-I carriers. These results demonstrate that HTLV-I infection is associated with an abnormal proliferation and differentiation of T cell progenitors in vitro and that the T-CFC from HTLV-I-seropositive individuals are infected, suggesting that T-CFC abnormalities may play a predominant role in the pathophysiology of HTLV-I.

Interferon-beta treatment does not elevate cortisol in multiple sclerosis

Interferons (IFN) are used to treat cancer and multiple sclerosis (MS). High doses of IFN elevate serum cortisol, which may indirectly affect the course of either of these diseases. IFN-induced elevation of serum cortisol could speed recovery from exacerbations of MS. We find that IFN-beta at 9 or 45 MU every other day does not elevate serum or urine cortisol in MS. Clinical effects of IFN-beta in MS are likely to be direct, and not mediated indirectly through alteration of serum cortisol levels.

Changes in leukocyte recirculation, NK cell activity, and HLA-DR expression in peripheral blood mononuclear cells of MS patients treated with Poly ICLC

To investigate the cellular immune effects of the interferon inducer, Poly ICLC, in humans, peripheral blood mononuclear cells from patients with multiple sclerosis receiving Poly ICLC as part of a preliminary clinical trial were studied. Peripheral blood mononuclear cell phenotype analysis using fluoresceinated monoclonal antibodies and flow microfluorometry showed decreases in the percentages and absolute numbers of all lymphocyte subsets 24 h after infusion. These changes returned toward baseline at 48 h except the percentage of CD-4 positive cell which increased above baseline levels. The percentage of HLA-DR antigen positive cells and CD-16 (Leu 11a) positive cells were increased 24 h after infusion but returned to baseline at 48 h. NK activity as determined by chromium release from K562 target cells was decreased at 24 h but increased 48 h after drug infusion. The increases in percentages of HLA-DR antigen and CD-16 positive cells at 24 h and NK activity at 48 h are consistent with the in vitro effects of IFN while the decreases in peripheral blood mononuclear cells are suggestive of changes in cell recirculation.