JAK-INHIBITORS DISRUPT CD14+/CD4+CELL INTERACTION SUPPRESSING RHO-GTPASE DEPENDENT LEUKOCYTE RECRUITMENT TO JOINTS OF RA PATIENTS

Background While examining arthritis development due hyperactivated Rho-GTPases in a mouse model, we found that macrophages with hyperactive Rho-GTPases regulate the migration of thymic T regulatory cells to peripheral lymphoid organs, which contributed to arthritis development Interestingly, T cells reciprocally upregulate Rho-GTPases leading to suppression of homing and formation of a mechanosensory complex of centered around β 1 -intergrin facilitating migration. Objectives In response to the finding in mice we sought to explore this relationship in patients diagnosed with RA, aiming to expand understanding how different treatments affect the molecular mechanisms we observed in mice. Methods To confirm if similar interaction mechanisms between macrophages and T cells are present in RA patients, we used paired transcriptome (RNAseq) of CD14 + and CD4 + cells from 80 RA patients active on conventional DMARDs prior to treatment with TNF-inhibitors (exploratory cohort) and from 56 RA patients with inactive disease on various DMARD treatment (confirmatory cohort). In both cohorts, patients were stratified by mean expression of CDC42 in CD14 + cells to mimic hyper activation of Rho-GTPases. Transcriptomics of CD14 + and CD4 + cells were analyzed and translated into clinical correlates. Results Examining the exploratory cohort, we found a reciprocal upregulation of Rho-GTPases across the cell types. The CDC42 hi group had upregulation of RHOA and RAC1 in CD14 + cells and CDC42, RAC1 and RHOA in CD4 + cells. Upregulation of IL6 , TLR4 and inflammasome units IL18R1 and IL1R2 , NLRP3 signified pro-inflammatory phenotype of those cells. Furthermore, CDC42 hi CD14 + and CD4 + cells shared the upregulation of AP-1 TFs, and the circadian rhythm controlling molecules PER1 , AHR and KLF6 assisting cell migration. Next, CDC42 hi cells were enriched with a synovial macrophage marker CD163, and ITGB1 to facilitate focal adhesion and migration into joints. Moreover, high expression of CXCL-chemokines and CCL5 on CDC42 h i CD14 + cells indicated the ability to recruit T cells, and high CXCR4 on CDC42 hi CD4 + cells suggested their synovial destination. Unexpectedly, CDC42 hi CD14 + and CD4 + cells were not recognized by strong production of the key pro-arthritis cytokines TNF-α and IFN-γ. Consequently, the CDC42 hi profile of CD14 + and CD4 + cells was not predictive for clinical response to TNF-inhibition in the exploratory cohort. Examination of the confirmatory cohort revealed the majority of CDC42 hi CD14 + cells belong to the patients treated with conventional DMARDS, while CDC42 lo group were treated with JAK-inhibitors (20 vs 4, OR = 11.87, 95 % CI [3.387, 49.72], p <0.0001). We also found a correlation between CDC42 expression in CD14 + cells and DAS28 in patients treated with JAK-inhibitors ( r =0.5, p =0.0072) pointing at tight relation between the treatment effect and Rho-GTPase dependent processes. This significantly affected the Rho-GTPase dependent interaction between CD14 + and CD4 + cells. Transcriptional profile of CDC42 hi CD14 + cells of the confirmatory cohort showed many similarities with the exploratory cohort including upregulation of the canonical Rho-GTPases, ITGB1 and the inflammasome activation that were enhanced by upregulation of the vast number of ITGA and chemokines. Transcriptional regulation through AHR and KLF6 persisted, while AP-1 and PER1 was downregulated. In contrast to CD4+ cells of the exploratory cohort, CD4 + cells of the patients with CDC42 hi CD14 + cells were low in CDC42 , RAC1 and RHOA expression. Also, CD4 + cells were deficient in AP-1, AHR/KLF6 and PER1 . Conclusion Taken together, these data show that Rho-GTPases regulate interaction between CD14 + and CD4 + cells and their migration to RA joints. Treatment with JAK-inhibitors suppress the Rho-GTPase dependent recruitment to joints by changing communication between CD14 + and CD4 + cells. This finding opens new perspective to use Rho-GTPase signature to identify patients suitable for treatment with JAK-inhibitors and in predicting the treatment response. Disclosure of Interests None declared