IL-11 induces NLRP3 inflammasome activation
The objective of this study is to examine IL-11-induced mechanisms of inflammatory cell migration to the CNS. We report that IL-11 is produced at highest frequency by myeloid cells among the PBMC cell subsets. Patients with relapsing-remitting multiple sclerosis (RRMS) have an increased frequency of IL-11+ monocytes, IL-11+ and IL-11R+ CD4+ lymphocytes and IL-11R+ neutrophils in comparison to matched healthy controls (HCs).  IL-11+ and GM-CSF+ monocytes, CD4+ lymphocytes, and neutrophils accumulate in the cerebrospinal fluid (CSF). The effect of IL-11 in-vitro stimulation, examined using single cell RNA sequencing (scRNAseq), revealed the highest number of differentially expressed genes (DEGs) in classical monocytes, including upregulated NFKB1, NLRP3 and IL1B.  All CD4+ cell subsets had increased expression of S100A8/9 alarmin genes involved in NLRP3 inflammasome activation.  In IL-11R+-sorted cells from the CSF, classical and intermediate monocytes significantly upregulated the expression of multiple NLRP3 inflammasome-related genes, including complement, IL18, and migratory genes (VEGFA/B) in comparison to blood-derived cells. Therapeutic targeting of this pathway with aIL-11 mAb in mice with RR experimental autoimmune encephalomyelitis (EAE) decreased clinical scores, CNS inflammatory infiltrates and demyelination.  aIL-11 mAb treatment decreased the numbers of NFkBp65+, NLRP3+ and IL-1b+ monocytes in the CNS of mice with EAE.  The results suggest that IL-11/IL-11R signaling in monocytes represents a therapeutic target in RRMS. Overall design: IL-11R+ FACS sorted cells from peripheral blood of 3 MS patients, stimulated vs. unstimulated with IL-11. IL-11R+ FACS sorted cells from CSF vs. blood of 2 MS patients.