Modulation of CD4+ T Lymphocyte Lineage Outcomes with Targeted, Nanoparticle-Mediated Cytokine Delivery

Abstract

Within the immune system there is an exquisite ability to discriminate between "self " and "nonself" that is orchestrated by antigen-specific T lymphocytes. Genomic plasticity enables differentiation of naïve CD4+ T lymphocytes into either regulatory cells (Treg) that express the transcription factor Foxp3 and actively prevent auto-immune self destruction, or effector cells (Teff) that attack and destroy their cognate target. An example of such plasticity is our recent discovery that leukemia inhibitory factor (LIF) supports Treg maturation in contrast to IL-6 which drives development of the pathogenic Th17 effector phenotype. This has revealed a LIF/IL6 axis in T cell development which can be exploited for modulation using targeted cytokine delivery. Here we demonstrate that LIF-loaded nanoparticles (NPs) directed to CD4+ T cells (i) oppose IL6-driven Th17 development; (ii) prolong survival of vascularized heart grafts in mice; and (iii) expand FOXP3+ CD4+ T cell numbers in a non-human primate model in vitro. In contrast, IL-6 loaded nanoparticles directed to CD4+ T cells increase Th17 development. Notably, nanoparticlemediated delivery was demonstrated to be critical: unloaded nanoparticles and soluble LIF or IL-6 controls failed to recapitulate the efficacy of cytokine-loaded nanoparticles in induction and/or expansion of Foxp3+ cells or Th17 cells. Thus, this targeted nanoparticle approach is able to harness endogenous immune-regulatory pathways, providing a powerful new method to modulating T cell developmental plasticity in immune-mediated disease indications.

Harnessing Nanoparticles for Immune Modulation

“…For example, it has been shown that polyclonal Tregs can be expanded using NPs coated with leukemia inhibitory factor [98]. A more antigen-specific approach includes using polymeric or monomeric peptide MHC (pMHC), which may selectively delete T cells expressing the cognate T cell receptor that recognizes the pMHC complex.…”

LIF in the regulation of T-cell fate and as a potential therapeutic

“…46 Other groups later showed that IL-6, known to be associated with inhibition of allo-tolerance, 68 promotes differentiation of TH17 cells in the presence of transforming growth factor-b. 61 When exploring possible interactions between LIF and IL-6, a head-to-head study revealed that LIF and IL-6 function as polar opposites in CD4 þ T cells, 34,69 as illustrated in Figure 3. LIF directly promoted the Treg lineage-specific transcription factor, Foxp3, while simultaneously repressing TH17 lineage-specific genes including the transcription factor RORgt: conversely, IL-6 inhibited expression of Foxp3 and promoted RORgt.…”

“…LIF directly promoted the Treg lineage-specific transcription factor, Foxp3, while simultaneously repressing TH17 lineage-specific genes including the transcription factor RORgt: conversely, IL-6 inhibited expression of Foxp3 and promoted RORgt. 34,69 Thus a critical LIF/ IL-6 axis in T-cell lineage maturation was first identified, as modelled in Figure 4.…”

“…However, delivery of LIF within a biodegradable nano-particulate carrier (LIFnano) targeted to CD4 þ T cells has proved efficacious in Treg induction without toxicity. 34,69 The LIF-nano are constructed to provide a sustained low-level release of LIF to the immediate environment of the CD4 þ T cell in a paracrine fashion and it has been demonstrated that LIF-nano (i) oppose IL-6-driven Th17 development; (ii) prolong survival of vascularised heart grafts in mice; and (iii) expand FOXP3 þ CD4 þ T-cell numbers in a non-human primate model in vitro. 69 Moreover, using rat neural precursor cells, direct evidence of LIF-nanomediated expansion of dopaminergic neurons has been obtained.…”

Neurological disorders and therapeutics targeted to surmount the blood–brain barrier

“…This nanoformulation should prove to have substantial application for therapeutics in multiple sclerosis. 161 Diagnostic applications for multiple sclerosis include glyconanoparticles formulated from cross-linked iron oxide nanoparticles modified with sialyl Lewis X, a ligand specific for selectins. Magnetic resonance imaging has shown increased accumulation of these targeted nanoparticles in an experimental autoimmune encephalomyelitis rat model.…”