Recombinant soluble IFN receptor (sIFNAR2) exhibits intrinsic therapeutic efficacy in a murine model of Multiple Sclerosis

Microglial Phenotypic Transition: Signaling Pathways and Influencing Modulators Involved in Regulation in Central Nervous System Diseases

Microglia are macrophages that reside in the central nervous system (CNS) and belong to the innate immune system. Moreover, they are crucially involved in CNS development, maturation, and aging; further, they are closely associated with neurons. In normal conditions, microglia remain in a static state. Upon trauma or lesion occurrence, microglia can be activated and subsequently polarized into the pro-inflammatory or anti-inflammatory phenotype. The phenotypic transition is regulated by numerous modulators. This review focus on the literature regarding the modulators and signaling pathways involved in regulating the microglial phenotypic transition, which are rarely mentioned in other reviews. Hence, this review provides molecular insights into the microglial phenotypic transition, which could be a potential therapeutic target for neuroinflammation.

Structural integrity with functional plasticity: what type I IFN receptor polymorphisms reveal

The type I IFNs activate an array of signaling pathways, which are initiated after IFNs bind their cognate receptors, IFNα/β receptor (IFNAR)1 and IFNAR2. These signals contribute to many aspects of human health including defense against pathogens, cancer immunosurveillance, and regulation of inflammation. How these cytokines interact with their receptors influences the quality of these signals. As such, the integrity of receptor structure is pivotal to maintaining human health and the response to immune stimuli. This review brings together genome wide association studies and clinical reports describing the association of nonsynonymous IFNAR1 and IFNAR2 polymorphisms with clinical disease, including altered susceptibility to viral and bacterial pathogens, autoimmune diseases, cancer, and adverse reactions to live-attenuated vaccines. We describe the amino acid substitutions or truncations induced by these polymorphisms and, using the knowledge of IFNAR conformational changes, IFNAR-IFN interfaces and overall structure-function relationship of the signaling complexes, we hypothesize the effect of these polymorphisms on receptor structure. That these predicted changes to IFNAR structure are associated with clinical manifestations of human disease, highlights the importance of IFNAR structural integrity to maintaining functional quality of these receptor-mediated responses. Type I IFNs are pivotal to innate immune responses and ultimately, to human health. Understanding the consequences of altered structure on the actions of these clinically significant cell receptors provides important information on the roles of IFNARs in health and disease.

Antiviral, Immunomodulatory and Antiproliferative Activities of Recombinant Soluble IFNAR2 without IFN-ß Mediation

Soluble receptors of cytokines are able to modify cytokine activities and therefore the immune system, and some have intrinsic biological activities without mediation from their cytokines. The soluble interferon beta (IFN-ß) receptor is generated through alternative splicing of IFNAR2 and has both agonist and antagonist properties for IFN-ß, but its role is unknown. We previously demonstrated that a recombinant human soluble IFN-ß receptor showed intrinsic therapeutic efficacy in a mouse model of multiple sclerosis. Here we evaluate the potential biological activities of recombinant sIFNAR2 without the mediation of IFN-ß in human cells. Recombinant sIFNAR2 down-regulated the production of IL-17 and IFN-ɣ and reduced the cell proliferation rate. Moreover, it showed a strong antiviral activity, fully protecting the cell monolayer after being infected by the virus. Specific inhibitors completely abrogated the antiviral activity of IFN-ß, but not that of the recombinant sIFNAR2, and there was no activation of the JAK-STAT signaling pathway. Consequently, r-sIFNAR2 exerts immunomodulatory, antiproliferative and antiviral activities without IFN-ß mediation, and could be a promising treatment against viral infections and immune-mediated diseases.

The presence and suppressive activity of myeloid-derived suppressor cells are potentiated after interferon-β treatment in a murine model of multiple sclerosis

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the human central nervous system (CNS), mainly affecting young adults. Among the immunomodulatory disease modifying treatments approved up to date to treat MS, IFN-β remains to be one of the most widely prescribed for the Relapsing-Remitting (RR) variant of the disease, although its mechanism of action is still partially understood. RR-MS variant is characterized by phases with increasing neurological symptoms (relapses) followed by periods of total or partial recovery (remissions), which implies the existence of immunomodulatory agents to promote the relapsing-to-remitting transition. Among these agents, it has been described the immunosuppressive role of a heterogeneous population of immature myeloid cells, namely the myeloid-derived suppressor cells (MDSCs) during the clinical course of the experimental autoimmune encephalomyelitis (EAE), the most used MS model to study RRMS. However, it is still unknown how the current MS disease modifying treatments, e.g. IFN- β, affects to MDSCs number or activity. Our present results show that a single injection of IFN-β at the onset of the clinical course reduces the severity of the EAE, enhancing the presence of MDSCs within the smaller demyelinated areas. Moreover, the single dose of IFN-β promotes MDSC immunosuppressive activity both in vivo and in vitro, augmenting T cell apoptosis. Finally, we show that IFN-ß preserves MDSC immaturity, preventing their differentiation to mature and less suppressive myeloid cell subsets. Taking together, all these data add new insights into the mechanism of IFN-β treatment in EAE and point to MDSCs as a putative endogenous mediator of its beneficial role in this animal model of MS.

Interferons in Traumatic Brain and Spinal Cord Injury: Current Evidence for Translational Application

This review article provides a general perspective of the experimental and clinical work surrounding the role of type-I, type-II, and type-III interferons (IFNs) in the pathophysiology of brain and spinal cord injury. Since IFNs are themselves well-known therapeutic targets (as well as pharmacological agents), and anti-IFNs monoclonal antibodies are being tested in clinical trials, it is timely to review the basis for the repurposing of these agents for the treatment of brain and spinal cord traumatic injury. Experimental evidence suggests that IFN-α may play a detrimental role in brain trauma, enhancing the pro-inflammatory response while keeping in check astrocyte proliferation; converging evidence from genetic models and neutralization by monoclonal antibodies suggests that limiting IFN-α actions in acute trauma may be a suitable therapeutic strategy. Effects of IFN-β administration in spinal cord and brain trauma have been reported but remain unclear or limited in effect. Despite the involvement in the inflammatory response, the role of IFN-γ remains controversial: although IFN-γ appears to improve the outcome of traumatic spinal cord injury, genetic models have produced either beneficial or detrimental results. IFNs may display opposing actions on the injured CNS relative to the concentration at which they are released and strictly dependent on whether the IFN or their receptors are targeted either via administration of neutralizing antibodies or through genetic deletion of either the mediator or its receptor. To date, IFN-α appears to most promising target for drug repurposing, and monoclonal antibodies anti IFN-α or its receptor may find appropriate use in the treatment of acute brain or spinal cord injury.