Immune activation and IL-12 production during acute/early HIV infection in the absence and presence of highly active, antiretroviral therapy.

Suppressed IL-12 production and maladaptive immune activation, both of which are ameliorated by successful highly active antiretroviral therapy (HAART), are thought to play important roles in the immunopathogenesis of chronic HIV infection. Despite the important effects of the immunological and virological events of early HIV infection on subsequent disease progression, IL-12 production and immune activation in early infection remain under-defined. To quantify IL-12 production and immune activation during acute/early HIV infection, in the presence and absence of HAART, we performed a prospective, longitudinal study of participants in the Baltimore site of the Acute Infection and Early Disease Research Program, with cross-sectional comparison to healthy control subjects. PBMC cytokine productive capacity and plasma immune activation markers [soluble CD8 (sCD8), sCD4, granzyme B, neopterin, beta2-microglobulin, sIL-2R, sTNFRI, sTNFRII, and IL-12p70] were quantified by ELISA. Notably, PBMC from patients with acute/early HIV infection exhibited in vivo IL-12p70 production along with increased, maximal in vitro IL-12 production. Further, despite evidence from plasma markers of generalized immune activation, no elevation in plasma levels of sCD4 was observed, suggesting relative blunting of in vivo CD4+ T cell activation from the beginning of HIV infection. Finally, despite successful virological responses to HAART, heightened in vivo CD8+ T cell activation, IL-12 production, and IFN activity were sustained for at least 6 months during primary HIV infection. These data underscore the need for comparative mechanistic analysis of the immunobiology of early and chronic HIV infection.

Modulation of the IL-12/IFN-gamma axis by IFN-alpha therapy for hepatitis C.

Although IFN-alpha forms the foundation of therapy for chronic hepatitis C, only a minority of patients has a sustained response to IFN-alpha alone. The antiviral activities of IFN-alpha formed the rationale for its use in viral hepatitis. However, IFN-alpha and the other Type I IFNs are also pleiotropic immune regulators. Type I IFNs can promote IFN-gamma production by activating STAT4 but can also inhibit production of IL-12, a potent activator of STAT4 and IFN-gamma production. The efficacy of IFN-alpha in the treatment of hepatitis C may therefore depend in part on the balance of IFN-gamma-inducing and IL-12-suppressing effects. We characterized the effects of pegylated IFN-alpha therapy for hepatitis C on the capacity of patients' PBMC to produce IL-12 and IFN-gamma ex vivo. Cells from patients with a sustained virological response to therapy had significantly greater levels of IFN-alpha-driven IFN-gamma production prior to treatment than those from nonresponding patients. No differences in pretreatment IL-12 productive capacity were seen between patient groups. However, therapy with IFN-alpha led to suppression of inducible IL-12 production throughout the course of therapy in both groups of patients.

Phase I and pharmacokinetic studies of CYT-6091, a novel PEGylated colloidal gold-rhTNF nanomedicine.

PURPOSE: A novel nanomedicine, CYT-6091, constructed by simultaneously binding recombinant human tumor necrosis factor alpha (rhTNF) and thiolyated polyethylene glycol to the surface of 27-nm colloidal gold particles, was tested in a phase I dose escalation clinical trial in advanced stage cancer patients. EXPERIMENTAL DESIGN: CYT-6091, whose dosing was based on the amount of rhTNF in the nanomedicine, was injected intravenously, and 1 cycle of treatment consisted of 2 treatments administered 14 days apart. RESULTS: Doses from 50 µg/m(2) to 600 µg/m(2) were well tolerated, and no maximum tolerated dose (MTD) was reached, as the highest dose exceeded the target dosage of 1-mg rhTNF per treatment, exceeding the previous MTD for native rhTNF by 3-fold. The first 2 patients on the study, each receiving 50 µg/m(2), did not receive any prophylactic antipyretics or H2 blockade. A predicted, yet controllable fever occurred in these patients, so all subsequently treated patients received prophylactic antipyretics and H2 blockers. However, even at the highest dose rhTNF's dose-limiting toxic effect of hypotension was not seen. Using electron microscopy to visualize nanoparticles of gold in patient biopsies of tumor and healthy tissue showed that patient biopsies taken 24 hours after treatment had nanoparticles of gold in tumor tissue. CONCLUSIONS: These data indicate that rhTNF formulated as CYT-6091 may be administered systemically at doses of rhTNF that were previously shown to be toxic and that CYT-6091 may target to tumors. Future clinical studies will focus on combining CYT-6091 with approved chemotherapies for the systemic treatment of nonresectable cancers.

Interferon-beta therapy for multiple sclerosis induces reciprocal changes in interleukin-12 and interleukin-10 production.

Interleukin-12 is critical to the pathogenesis of experimental autoimmune encephalomyelitis in multiple species. Interleukin-10, a dominant endogenous inhibitor of interleukin-12, is largely protective in these experimental surrogates for multiple sclerosis. Such data have suggested that an interleukin-12/interleukin-10 immunoregulatory circuit is a key determinant of disease expression in experimental autoimmune encephalomyelitis. For multiple sclerosis itself, compatible cytokine data have been reported. The mechanisms underlying the beneficial effects of interferon-beta in multiple sclerosis remain unclear, hampering the search for more effective therapies. Of note, interferon-beta has reciprocal effects on these cytokines in vitro, suppressing interleukin-12 and augmenting interleukin-10 production. To examine the effects of interferon-beta on the interleukin-12/interleukin-10 axis in multiple sclerosis, we characterized the production of these cytokines by peripheral blood mononuclear cells from patients beginning therapy with interferon-beta. Before therapy, multiple sclerosis patients exhibited increased stimulatable interleukin-12 production compared with controls. Interferon-beta therapy leads to inhibition of interleukin-12 and augmentation of interleukin-10 production, significantly elevating the ratio of secreted interleukin-10 to interleukin-12. These effects, observed equally in patients with relapsing-remitting and progressive disease, indicate that interferon-beta affects the interleukin-12/interleukin-10 axis in ways thought to be beneficial to multiple sclerosis patients. More specific therapeutic targeting of these pathways may be warranted.