Background/Purpose: While examining arthritis development in GGTaseI-deficient mice, we found that hyperactive Rho-GTPases regulate the thymic egress of CD4+ T cells to the peripheral lymphoid organs, which contributed to arthritis development.

Methods: Paired transcriptome of blood CD14⁺ and CD4⁺ cells of RA patients with active (n=80) and inactive (n=59) disease was prepared by RNA-seq (Illumina). In both cohorts, patients were stratified by CDC42 expression in CD14⁺ and transcriptomics was compared. We also used a scRNAseq dataset of synovial macrophages to confirm presence of complementary CD14⁺ cells in joint.

Results: Rho-GTPases CDC42, RAC1 and RHOA were concordantly expressed in CD14⁺ and CD4⁺ cells being associated with the Circadian rhythm entrainment, oxidative phosphorylation and cell migration. In CD14⁺ cells in the active disease, all three Rho-GTPases participated in regulation of energy supply through control of the Oxidative phosphorylation and the Electron transport chain and TCA cycle (KEGG), which could not be found in inactive RA. Reciprocal activation of Rho-GTPases by β-integrins and Toll-like receptors suggests a direct CD14⁺/CD4⁺ cell interaction, which was marked by aggressive pro-inflammatory phenotype, activation of AP-1 and massive cytokine production. Furthermore, Rho-GTPase high leukocytes were enriched with CD163 indicating synovial destination. We utilized the UMAP analysis of the synovial CD14⁺ cells scRNA-seq and identified the cell clusters recognized by high transcription of Rho-GTPases. In comparison to the remaining cells, those clusters were specifically enriched with RAC1, CD163, ID2 and its upstream regulator ZEB2, AP-1 complex and CCL3 genes, which confirmed transcriptional similarity of Rho-GTPase high macrophages in synovium and peripheral blood.

We found that CDC42 expression CD14⁺ cells correlated positively with DAS28, and DAS28 was significantly higher in patients with CDC42^hiCD14⁺ cells (p=0.008) and corresponded to high protein and mRNA production of TNF-α, IL-1β and IL-10 by CDC42^hi CD14⁺ cells. Patients treated with JAK-inhibitors had significantly lower CDC42 expression on CD14⁺ cells (p< 0.0001) and decreased DAS28 (p< 0.0001).

Conclusion: Here, we demonstrate that Rho-GTPases regulate interaction between CD14⁺ and CD4⁺ cells and direct their migration to RA joints. JAK-inhibition suppress the Rho-GTPase dependent migration by disrupting CD14⁺/CD4⁺ communication. Thus, Rho-GTPase signature could identify RA patients sensitive to treatment with JAK-inhibitors.

« Back to ACR Convergence 2022

ACR Meeting Abstracts - https://acrabstracts.org/abstract/rho-gtpase-expression-recruits-cd14-cells-to-joints-in-rheumatoid-arthritis-and-predicts-good-response-to-jak-inhibitor-treatment/