Steady-state production of IL-4 modulates immunity in mouse strains and is determined by lineage diversity of iNKT cells

Abstract

iNKT cells can produce high levels of IL-4 early during infection. However, indirect evidence suggests they may produce this immunomodulatory cytokine in the steady state. Through intracellular staining for transcription factors, we define 3 subsets of iNKT cells that produce distinct cytokines (NKT1, NKT2, and NKT17), which represent diverse lineages and not developmental stages as previously thought. These subsets exhibit substantial inter-strain variation in numbers. In several strains, including BALB/c, NKT2 cells are abundant and stimulated by self-ligands to produce IL-4. In these strains, steady state IL-4 conditions CD8 T cells to become “memory-like”, increases serum IgE levels, and causes dendritic cells to produce chemokines. Thus iNKT cell derived IL-4 alters immune properties under normal steady state conditions.

The Thymic Microenvironment Differentially Regulates Development and Trafficking of Invariant NKT Cell Sublineages

“…Initially, phenotypic and functional characterization of iNKT cell differentiation described the presence of four developmental stages in which effector differentiation was associated with upregulation of the surface Ags CD44 and NK1.1, production of IFN-g and IL-4, and stable expression of the Th1-lineage transcription factor T-bet (2). More recent studies have, however, shown that terminally differentiated iNKT thymocytes are composed of alternatively polarized Th1, Th2, and Th17 sublineages characterized by expression of the transcription factors T-bet, GATA-3, and RORgt, respectively (6). Whether iNKT polarization is a developmental consequence of lineage priming by transcription factors such as PLZF is currently an active field of research (7).…”

“…1B). A subsequent iNKT sublineage analysis using the cell surface markers CD27 and IL2Rb (6) revealed that between 40 and 50% of thymic NKT1, NKT2, and NKT17 sublineages express CX3CR1 mRNA (Fig. 1C), that peripheral iNKT sublineages differentially express CX3CR1 mRNA in a tissue-specific manner (Fig.…”

A mutation within the SH2 domain of slp‐76 regulates the tissue distribution and cytokine production of iNKT cells in mice

“…The sequential lineage model suggests a gradual decrease of PLZFexpression following selection of iNKT cells which show a Th2-dominated cytokine profile during earlier and a Th1-dominated cytokine profile during later stages of intrathymic maturation [1,7]. The second model describes lineage diversification and simultaneous differentiation into Th1-, Th2-, or Th17-polarized subsets that are defined by the level of PLZF-expression [8]. Although many iNKT cells release both Th1 and Th2 cytokines on a single cell level [9], the production of IL-17 and IFN-γ is mutually exclusive within NK1.1 − cells [10][11][12].…”

“…Specifically, liver and spleen constitute the main source for the Th1-polarized sublineage which is PLZF low . Th2-or Th-17-polarized iNKT cells maintain their PLZF-expression at high or intermediate levels, respectively, and are primarily recovered from the lungs and peripheral lymph nodes [8,12,15]. Both subsets frequently express IL-17RB [18] and NP-1 which characterizes iNKT cells that recently emigrated from the thymus [19].…”

“…Although many iNKT cells release both Th1 and Th2 cytokines on a single cell level [9], the production of IL-17 and IFN-γ is mutually exclusive within NK1.1 − cells [10][11][12]. Several transcription factors, such as Egr2, T-bet, ThPOK, Id2, Id3, and the Tec kinases Itk and Rlk have been implicated in the differentiation of iNKT cell subsets [6,8,[13][14][15][16][17] which home to distinct tissues. Specifically, liver and spleen constitute the main source for the Th1-polarized sublineage which is PLZF low .…”