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

Experimental autoimmune encephalomyelitis (EAE) as a model for multiple sclerosis (MS)

Experimental autoimmune encephalomyelitis (EAE) is the most commonly used experimental model for the human inflammatory demyelinating disease, multiple sclerosis (MS). EAE is a complex condition in which the interaction between a variety of immunopathological and neuropathological mechanisms leads to an approximation of the key pathological features of MS: inflammation, demyelination, axonal loss and gliosis. The counter-regulatory mechanisms of resolution of inflammation and remyelination also occur in EAE, which, therefore can also serve as a model for these processes. Moreover, EAE is often used as a model of cell-mediated organ-specific autoimmune conditions in general. EAE has a complex neuropharmacology, and many of the drugs that are in current or imminent use in MS have been developed, tested or validated on the basis of EAE studies. There is great heterogeneity in the susceptibility to the induction, the method of induction and the response to various immunological or neuropharmacological interventions, many of which are reviewed here. This makes EAE a very versatile system to use in translational neuro- and immunopharmacology, but the model needs to be tailored to the scientific question being asked. While creating difficulties and underscoring the inherent weaknesses of this model of MS in straightforward translation from EAE to the human disease, this variability also creates an opportunity to explore multiple facets of the immune and neural mechanisms of immune-mediated neuroinflammation and demyelination as well as intrinsic protective mechanisms. This allows the eventual development and preclinical testing of a wide range of potential therapeutic interventions.

Synthetic double-stranded RNAs are adjuvants for the induction of T helper 1 and humoral immune responses to human papillomavirus in rhesus macaques

Toll-like receptor (TLR) ligands are being considered as adjuvants for the induction of antigen-specific immune responses, as in the design of vaccines. Polyriboinosinic-polyribocytoidylic acid (poly I:C), a synthetic double-stranded RNA (dsRNA), is recognized by TLR3 and other intracellular receptors. Poly ICLC is a poly I:C analogue, which has been stabilized against the serum nucleases that are present in the plasma of primates. Poly I:C₁₂U, another analogue, is less toxic but also less stable in vivo than poly I:C, and TLR3 is essential for its recognition. To study the effects of these compounds on the induction of protein-specific immune responses in an animal model relevant to humans, rhesus macaques were immunized subcutaneously (s.c.) with keyhole limpet hemocyanin (KLH) or human papillomavirus (HPV)16 capsomeres with or without dsRNA or a control adjuvant, the TLR9 ligand CpG-C. All dsRNA compounds served as adjuvants for KLH-specific cellular immune responses, with the highest proliferative responses being observed with 2 mg/animal poly ICLC (p = 0.002) or 6 mg/animal poly I:C₁₂U (p = 0.001) when compared with immunization with KLH alone. Notably, poly ICLC—but not CpG-C given at the same dose—also helped to induce HPV16-specific Th1 immune responses while both adjuvants supported the induction of strong anti-HPV16 L1 antibody responses as determined by ELISA and neutralization assay. In contrast, control animals injected with HPV16 capsomeres alone did not develop substantial HPV16-specific immune responses. Injection of dsRNA led to increased numbers of cells producing the T cell–activating chemokines CXCL9 and CXCL10 as detected by in situ hybridization in draining lymph nodes 18 hours after injections, and to increased serum levels of CXCL10 (p = 0.01). This was paralleled by the reduced production of the homeostatic T cell–attracting chemokine CCL21. Thus, synthetic dsRNAs induce an innate chemokine response and act as adjuvants for virus-specific Th1 and humoral immune responses in nonhuman primates.

Novel adjuvants that facilitate the induction of strong cellular immunity could be of help in the design of vaccine strategies to combat infections such as HIV or tuberculosis. Our immune cells possess archaic receptors recognizing structures of infectious pathogens, and the interaction of these receptors with their ligands results in an activation of the immune system. Here we exploited synthetic forms of one of these ligands, i.e., dsRNA, to define an adjuvant for the induction of cellular immune responses in primates. We injected model and viral proteins together with three different forms of dsRNA subcutaneously (s.c.) in rhesus macaques, and all compounds served as adjuvants for the induction of cellular immunity without the incidence of major side effects. These adjuvant effects depended on the adjuvant dose and coincided with profound alterations in the chemokine production in the draining lymph nodes. dsRNA also helped to induce cellular and humoral immune responses against capsomeres of low immunogenicity derived from the human papillomavirus 16, the causative agent in about 50% of all cases of cervical cancer worldwide. Therefore, formulations involving synthetic dsRNA are promising candidates for development of novel vaccines.

Not-so-sweet sixteen: the role of IL-16 in infectious and immune-mediated inflammatory diseases

Over the past two decades, our understanding of interleukin-16 (IL-16) has increased substantially. Initial studies characterizing IL-16 as a chemotactic cytokine (but not a chemokine) just scratched the surface of the unique properties of this cytokine. Since then, scientists have determined that IL-16 has a wide range of effects on cells, including upregulation of CD25, induction of cells to progress to the G(1) phase, inhibition of antigen- specific proliferation yet with retained antigen nonspecific proliferative properties, and discovery of a novel neuronal form with unique properties. Recently, a plethora of studies have implicated IL-16 in exacerbation of infectious, immune-mediated, and autoimmune inflammatory disorders, including atopic dermatitis, irritable bowel syndrome, systemic lupus erythematosus, neurodegenerative disorders, and viral infections. Herein, we review the body of evidence supporting a role for IL-16 in infectious and immune-mediated inflammatory disorders and explore the known and possible mechanism of actions in the numerous diseases.

Ethanol decreases natural killer cell activation but only minimally affects anatomical distribution after administration of polyinosinic:polycytidylic acid: role in resistance to B16F10 melanoma

BACKGROUND

Natural killer (NK) cells are critical in resistance to B16F10 lung metastases in B6C3F1 mice. Activation of NK cells by polyinosinic:polycytidylic acid (poly I:C; 0.1 mg, intraperitoneally) increases resistance to B16F10 cells. This effect is reduced after administration of ethanol (EtOH; 6 g/kg by oral gavage). The present study was conducted to determine whether decreased resistance is due to alteration of the distribution and/or the activation of NK cells.

METHODS

These parameters were measured in the spleen, lungs, and peripheral blood 4 and 12 hr after EtOH and poly I:C administration. For assessing the time after poly I:C administration during which NK cells are important in resistance to B16F10 cells, anti-NK1.1 antibody was used to deplete NK cells in vivo 48 hr before and 0, 6, 12, and 24 hr after intravenous injection of B16F10 tumor cells.

RESULTS

Depletion of NK cells at any time up to 12 hr after B16F10 administration significantly increased the number of tumor nodules in the lungs, but depletion at 24 hr had a smaller effect. Flow cytometry revealed that there was a small but significant increase in the percentage of NK cells in the lungs at 12 hr, which was not changed by EtOH. Corresponding NK cell lytic function in the lungs was increased significantly at both 4 and 12 hr by poly I:C. However, the increase was not significantly different from the naive control value at 4 hr in mice treated with poly I:C plus EtOH, indicating that EtOH decreased activation of NK cells in the lungs at 4 hr. In the spleen, no treatment significantly altered the percentage of NK cells at 4 or 12 hr. However, poly I:C significantly enhanced lytic function, and this enhancement was suppressed by EtOH (by approximately 50%). In the blood, the only significant change in NK cell percentage or lytic activity was an increase in the percentage of NK cells at 12 hr, which was equivalent in the poly I:C and the poly I:C plus EtOH groups.

CONCLUSIONS

These results demonstrate that EtOH partially abrogates the poly I:C-induced enhancement of resistance to B16F10 cells and that decreased activation of NK cells in the lungs at a critical time early in the response to poly I:C may contribute to this effect. Other parameters could also contribute, but there was little support for an important role for changes in NK cell distribution.