A hierarchical role of IL-25 in ILC development and function at the lung mucosae following viral-vector vaccination

Abstract

This study demonstrates that modulation of IL-25 and IL-33 cytokines responsible for innate lymphoid cell 2 (ILC2) activation/function can differentially regulate ILC profiles at the vaccination site, in a vaccine route-dependent manner. Specifically, recombinant fowlpox (rFPV) vector-based vaccine co-expressing an adjuvant that transiently sequestered IL-25 (FPV-HIV-IL-25 binding protein), delivered intramuscularly (i.m.) was able to induce significantly lower IL-25R + ILC2-deived IL-13 and ILC1/ILC3-derived IFN-γ expression with significantly elevated IL-17A in muscle. In contrast, intranasal (i.n.) delivery was able to induce all three known ILC2 subsets (ST2/IL-33R + , IL-25R + , and TSLPR + ILC2) to express varying amounts of IL-13 in lung, and also the TSLPR + ILC2 to express IL-4, unlike the unadjuvanted control, which only showed ST2/IL-33R + ILC2 to express IL-13. Interestingly, the sequestration of IL-25 in lung also induced a unique lineage − ST2/IL-33R − IL-25R − TSLPR − ILC2 population to express elevated IL-13 and IL-4. Moreover, both i.m. and, i.n. FPV-HIV-IL-25BP vaccination induced significantly elevated ILC1/ILC3-derived IL-17A in lung, indicating that ILC2 could directly impact ILC1/ILC3 activity. To our surprise, transient sequestration of IL-33 at the lung mucosae did not alter the lung ILC2 profiles or activity. These inhibitor studies showed that in the context of i.n. viral vector vaccination, IL-25 plays a predominant role in early ILC development/regulation than IL-33, and likely acts as a master regulator of ILC. Our previous findings have indicated that level of IL-4/IL-13 at the vaccination site impacts the quality/avidity of T cell immunity. Taken together data suggest that IL-25 binding protein could be used as an effective i.m. not an i.n. adjuvant to enhance quality of vaccine-specific T cell immunity. These findings evoke the notion that route-dependent manipulation of ILCs according to the target pathogen could be exploited to design more effective vaccines against chronic pathogens in the future.

Mucosal IL-4R antagonist HIV vaccination with SOSIP-gp140 booster can induce high-quality cytotoxic CD4+/CD8+ T cells and humoral responses in macaques

“…When unravelling the immune mechanisms linked to our vaccines, we have shown that IL-4R antagonist adjuvanted vaccine induce significantly reduced ILC2-derived IL-13 at the vaccination site 24 h post-delivery compared to the control 17 , responsible for the observed immune outcomes 24,26 . Recently, using range of viral vector-based vaccines we have also demonstrated that ILC-derived IL-13 is the master regulator of different ILC subsets, as well as DC activity at the early stage of vaccination, shaping the downstream adaptive immune outcomes [17][18][19][20][21]23 . Specifically, although IL-13 is known to be detrimental for high avidity T cell induction 13,15,23 , low IL-13 at the vaccination site has shown to be crucial for effective antibody differentiation/ formation 24,25 .…”

“…Thus, the discrepancies observed in Env-specific antibody outcomes with the two vaccines, could most likely be associated with the level of IL-13 at the vaccination site (unadjuvanted > IL-4R antagonist). Interestingly, for decades different adjuvants have been used to manipulate DC activity to alter the adaptive immune outcomes [67][68][69] We have recently found that not only the co-expressed adjuvants [17][18][19] but adjuvants used with protein-based www.nature.com/scientificreports/ vaccines can significantly alter the ILC-derived IL-13 profiles at the vaccination site (S. Fig. 12), which subsequently modulate DC activity.…”

“…Many studies have now shown that mucosal administered vaccination can induce sustained higher avidity mucosal T cells with better protective efficacy compared to systemic delivery [11][12][13][14][15][16] , however there has been limited interest in taking a mucosal HIV vaccine towards larger human trials. When trying to unravel the mechanisms behind mucosal verses systemic delivery upon vaccine outcomes, we have recently found that innate lymphoid cells type 2 (ILC2)-derived IL-13 at the vaccination site plays an important role in shaping the downstream adaptive immune outcomes in mice [17][18][19] . Specifically, reduced IL-13 at the vaccination site associated with mucosal delivery leads to recruitment of conventional dendritic cells 18,20,21 , resulting in high avidity/poly-functional CD8 + T cells, with low or no IL-13 expression 13,22,23 .…”

IL-13Rα2 Regulates the IL-13/IFN-γ Balance during Innate Lymphoid Cell and Dendritic Cell Responses to Pox Viral Vector-Based Vaccination

“…ILCs are generally divided into three distinct subsets, ILC1, ILC2, and ILC3, based on expression of cytokines, phenotypic markers, and transcription factors. Specifically, ILC2 are characterized by tissue specific surface expression of ST2/IL-33R (lung), IL-25R (muscle), or thymic stromal lymphopoietin receptor (TSLPR) (skin), and cytokines IL-4, IL-5, and IL-13, plus transcription factor GATA3 [ 24 , 25 , 26 , 27 ]. ILC1 and ILC3 are defined by the expression of NKp46, and their IFN-γ, IL-22, and IL-17A production capacity and linked to transcription factors T-bet and RORγt [ 27 ].…”

“…ILC1 and ILC3 are defined by the expression of NKp46, and their IFN-γ, IL-22, and IL-17A production capacity and linked to transcription factors T-bet and RORγt [ 27 ]. However, several studies have shown that the ILC populations can be highly plastic according to different cell/tissue milieus [ 24 , 25 , 28 , 29 ]. Recent studies in our laboratory have shown that following viral vector-based vaccination, ILC2 was the major source of IL-13 at the vaccination site 24 h post-delivery [ 24 , 30 ].…”