Enhanced Chondrogenesis of Induced Pluripotent Stem Cells From Patients With Neonatal‐Onset Multisystem Inflammatory Disease Occurs via the Caspase 1–Independent cAMP/Protein Kinase A/CREB Pathway

Abstract

Objective. Neonatal-onset multisystem inflammatory disease (NOMID) is a dominantly inherited autoinflammatory disease caused by NLRP3 mutations. NOMID pathophysiology is explained by the NLRP3 inflammasome, which produces interleukin-1␤ (IL-1␤).However, epiphyseal overgrowth in NOMID is resistant to anti-IL-1 therapy and may therefore occur independently of the NLRP3 inflammasome. This study was undertaken to investigate the effect of mutated NLRP3 on chondrocytes using induced pluripotent stem cells (iPSCs) from patients with NOMID.Methods. We established isogenic iPSCs with wild-type or mutant NLRP3 from 2 NOMID patients with NLRP3 somatic mosaicism. The iPSCs were differentiated into chondrocytes in vitro and in vivo. The phenotypes of chondrocytes with wild-type and mutant NLRP3 were compared, particularly the size of the chondrocyte tissue produced.Results. Mutant iPSCs produced larger chondrocyte masses than wild-type iPSCs owing to glycosaminoglycan overproduction, which correlated with increased expression of the chondrocyte master regulator SOX9. In addition, in vivo transplantation of mutant cartilaginous pellets into immunodeficient mice caused disorganized endochondral ossification. Enhanced chondrogenesis was independent of caspase 1 and IL-1, and thus the NLRP3 inflammasome. Investigation of the human SOX9 promoter in chondroprogenitor cells revealed that the CREB/ATF-binding site was critical for SOX9 overexpression caused by mutated NLRP3. This was supported by increased levels of cAMP and phosphorylated CREB in mutant chondroprogenitor cells.Conclusion. Our findings indicate that the intrinsic hyperplastic capacity of NOMID chondrocytes is dependent on the cAMP/PKA/CREB pathway, independent of the NLRP3 inflammasome.

Chronic inflammation triggered by the NLRP3 inflammasome in myeloid cells promotes growth plate dysplasia by mesenchymal cells

“…Furthermore, cultured stromal cells/osteoblasts from NOMID patients express higher levels of gene targets of the potent bone anabolic molecules, Wnts, and are more proliferative than control cells 16 . Accordingly, induced pluripotent stem cells from NOMID patients exhibit superior chondrogenic potential in vitro compared to normal cells 15 . Thus, hyper-active NLRP3 is apparently harmful to human, but not murine osteochondro-progenitors.…”

“…These cells maintain skeletal integrity through the production, organization and mineralization of the extracellular matrix; but aberrant activities of these cells in pathologic conditions such as osteoarthritis can cause degenerative hypertrophy such as osteophytes and Heberdeen’s nodes. Indeed, enhanced cAMP-dependent protein kinase activity and Wnt signaling in stromal cells/osteoblasts may contribute to the tumor-like phenotype of bony outgrowths in NOMID patients 15, 16 ; and hyper-activation of the NLRP3 inflammasome is presumed to promote chondrocyte apoptosis, thereby contributing to deafness in CAPS patients 6, 17 . Thus, it is possible that growth plate and epiphyseal dysplasia in NOMID may arise from aberrant NLRP3 actions in mesenchymal cells in addition to indirect effects via innate immune cells.…”

Neofunction of ACVR1 in fibrodysplasia ossificans progressiva

“…The 3DCI pellets cultured with 100 ng/mL Activin-A for 21 d in vitro were wrapped in 0.5 cm × 1 cm Gelfoam (Pfizer) and transplanted beneath the dorsal skin of immunodeficient NOD/SCID mice (CLEA Japan) (44). Four weeks later, transplanted 3DCI pellets were harvested and analyzed.…”

Genome Engineering for Personalized Arthritis Therapeutics

“…Another study found that iPSCs from a patient with an NLRP3 mutation causing neonatal onset multisystem inflammatory disease (NOMID) presented enhanced chondrogenesis. [115] iPSCs derived from unique patients have thus been shown to have highly variable differentiation potential as a result of different genetic backgrounds. [116,117] As these studies use patient-derived iPSCs, they cannot control for inherent genetic variability among cell lines that might also alter chondrogenic potential.…”