CRIP1 protein lactylation drives synovial proliferation in rheumatoid arthritis by hijacking p21 from CDK2
Background
Rheumatoid arthritis (RA) is a chronic autoimmune disease marked by persistent synovial inflammation and joint destruction. A key pathological feature is synovial hyperplasia, where the synovial lining thickens, yet its precise mechanisms remain elusive. RA synovium exhibits a metabolic shift towards increased glycolysis and lactate production. This study investigates how lactate metabolism and subsequent protein lactylation contribute to RA pathology, specifically focusing on the role of lactylated proteins in driving synovial proliferation, a gap in understanding RA progression.
Study Design
Researchers analyzed lactate production and protein lactylation in RA patients, correlating these with clinical disease activity. They identified Cysteine-rich intestinal protein 1 (CRIP1) as a markedly lactylated protein. To investigate its role, they used AAV-mediated delivery of a lactylation-deficient CRIP1 K49R mutant in animal models. Furthermore, Peptide-based interventions targeting CRIP1 K49 lactylation were tested for their ability to inhibit synovial hyperplasia and disease severity in both Collagen II-induced arthritis (CIA) and humanized NSG chimeric models.
Results
In RA patients, both lactate production and protein lactylation were elevated and showed a positive correlation with clinical disease activity. Among lactylated proteins, CRIP1 exhibited a marked increase in modification. Mechanistically, CRIP1 underwent MOF-mediated lactylation in RA synovial fibroblasts. This lactylated CRIP1 then hijacked the cell-cycle regulator p21, disrupting its interaction with cyclin-dependent kinase 2 (CDK2), thereby facilitating the G1/S phase transition. Functionally, AAV-mediated delivery of a lactylation-deficient CRIP1 K49R significantly reduced synovial proliferation compared with WT CRIP1.
Key Findings
- Lactate production and protein lactylation are elevated in RA patients and correlate with disease activity.
- Cysteine-rich intestinal protein 1 (CRIP1) shows a marked increase in lactylation in RA synovium.
- Lactylated CRIP1 hijacks
p21, disrupting its interaction withCDK2and facilitatingG1/Scell cycle transition. - AAV-mediated delivery of lactylation-deficient
CRIP1 K49Rsignificantly reduced synovial proliferation. - Peptide-based interventions targeting
CRIP1 K49lactylation effectively inhibited synovial hyperplasia and disease severity in animal models.
Why It Matters
This research identifies a novel, targetable mechanism for rheumatoid arthritis (RA) progression, shifting focus from traditional inflammatory pathways to metabolic reprogramming and protein modification. Targeting CRIP1 K49 lactylation offers a promising new therapeutic strategy for RA, potentially leading to peptide-based interventions that directly inhibit synovial hyperplasia. This could translate into more effective treatments that address the underlying cellular proliferation, rather than just managing inflammation. While preclinical, the use of peptide-based interventions suggests a pathway towards developing novel drugs that could be administered to modulate disease activity, potentially improving long-term outcomes for RA patients.
rheumatoid-arthritis
synovial-hyperplasia
lactylation
crip1
cell-cycle
peptide-therapy