Utilization of lipopolysaccharide challenge in cynomolgus macaques to assess IL-10 receptor antagonism.

The current era of drug discovery has been marked by a significant increase in the development of immune modulating agents to address a range of diseases such as cancer, chronic inflammation, and other conditions of dysregulated immunity. Non-clinical evaluation of these agents in animal models can be challenging, as the presence of an active immune state is often required in order to detect the effects of the test agent. Modulation of interleukin (IL)-10 signaling represents this type of situation in that altering IL-10 action in vivo can be difficult to appreciate in the absence of an ongoing immune response. The study presented here reports on the use of lipopolysaccharide (LPS) challenge in cynomolgus macaques to induce predictable inflammatory cytokine responses. The results showed that IL-10 receptor (IL-10R) blockade with an antagonist monoclonal antibody (mAb) dramatically enhanced the LPS-induced cytokine response, thus demonstrating in vivo pharmacologic activity of this immunomodulatory antibody. We submit that this approach could be applied to other cases where the intent of a candidate therapeutic is to modulate components of inflammatory cytokine responses.

Differential impact of PD-1 and/or interleukin-10 blockade on HIV-1-specific CD4 T cell and antigen-presenting cell functions.

UNLABELLED: Antigen persistence in chronic infections and cancer upregulates inhibitory networks, such as the PD-1 and interleukin-10 (IL-10) pathways, that impair immunity and lead to disease progression. These pathways are attractive targets for immunotherapy, as demonstrated by recent clinical trials of PD-1/PD-L1 blockade in cancer patients. However, in HIV-1 infection not all subjects respond to inhibition of either pathway and the mechanistic interactions between these two networks remain to be better defined. Here we demonstrate that in vitro blockade of PD-L1 and/or IL-10Rα results in markedly different profiles of HIV-1-specific CD4 T cell restoration. Whereas PD-L1 blockade leads to balanced increase in gamma interferon (IFN-γ), IL-2, and IL-13 secretion, IL-10Rα blockade preferentially restores IFN-γ production. In viremic subjects, combined PD-L1/IL-10Rα blockade results in a striking 10-fold increase in IFN-γ secretion by HIV-1-specific CD4 T cells that is not observed in subjects with spontaneous (elite controllers) or therapy-induced control of viral replication. In contrast to the dramatic increase in IFN-γ production, concurrent blockade has a marginal additive effect on IL-2 production, IL-13 secretion, and HIV-1-specific CD4 T cell proliferation. IFN-γ produced by Thelper cells upregulates PD-L1, HLA I/II, and IL-12 expression by monocytes. The effect of combined blockade on IFN-γ was dependent on reciprocal reinforcement through IL-12. These studies provide crucial information on the different immunoregulatory qualities of PD-1 and IL-10 in progressive disease and link exhausted virus-specific CD4 T cells and monocytes in the regulation of IFN-γ and IL-12 secretion. IMPORTANCE: Infection with HIV results in most people in uncontrolled viral replication and progressive weakening of the body defenses. In the absence of antiviral therapy, this process results in clinical disease, or AIDS. An important reason why HIV continues to multiply is that a population of white blood cells called CD4 T cells that targets the virus fails to work properly. At least part of this impairment is under the control of inhibitory mechanisms that can be blocked to improve the function of these CD4 T cells. In this report, we show that blocking one or two of the molecules involved, called PD-1 and IL-10, has different effects on the individual functions of these cells and that one is strongly improved. We investigate how these effects are caused by interactions between CD4 T cells and antigen-presenting cells. These observations can have implications for new therapeutic approaches in HIV infection.