A new therapeutic strategy for inhibiting pro-inflammatory macrophages in pre-clinical models of rheumatoid arthritis: using antagomir-155 encapsulated in pegylated liposomes

This PhD is a translational research project build to address basic immunological and clinical issues as follows. The basic immunological project aims to:

• Objective 1: Investigate the interaction between type I IFN and CHB susceptibility genes
• Objective 2: Identify cardiac targets of anti-SSA auto-Abs
• Objective 3: Explore inflammatory pathways involved in the pathogenesis of CHB

The clinical project aims to:

• Objective 1: Study fetal and neonatal health of CHB newborns from anti-SSA+ mothers
• Objective 2: Study long-term outcome of CHB offspring from anti-SSA+ mothers

By the end of the first year, the student is expected to:

• Have completed the experiments for objective 1 of the basic immunological project and be able to communicate about the preliminary results
• Have preliminary results for objective 3 of the basic immunological project
• Have completed the analysis of the dataset for the objective 1 of the clinical project and be able to submit a paper and communicate about the results

We found that an increased expression of miR-155 in monocytes/macrophages was responsible for the impaired differentiation of monocytes in anti-inflammatory macrophages. We have identified 7 microRNAs that differentiate monocytes of RA patients from those of healthy. Unfortunately, we could not confirm implication of new miR, except miR-155.  

Also, we demonstrated that miR-155-driven defect of anti-inflammatory macrophage differentiation was also present in 2 pre-clinical models of RA: serum-transfer-arthritis (STA) and collagen-induce-arthritis (CIA) mice. We validated the therapeutic strategy using antagomiR-155 encapsulated in PEG-liposomes for decreasing arthritis incidence and paw volume-size in CIA and STA. Moreover, PEG-liposomes were specific of monocytes and had no impact on other immune cells. Finally, we demonstrated a restoration of monocytes polarization in M2 macrophages in bone-marrow-derived-macrophages but also in mice synovial tissue.

Monocytes-macrophages are key players in the pathogenesis of Rheumatoid Arthritis (RA). An up-regulation of miR-155 expression has been shown in RA synovial macrophages, fibroblasts, peripheral blood and synovial fluid CD14+ monocytes. Our group has demonstrated epigenetic mechanism driving preferential differentiation of RA monocyte into pro-inflammatory macrophages published in The Journal of Immunology (Paoletti A et al J Immunol. 2019 Oct 1;203(7):1766-1775).  

We found that an increased expression of miR-155 in monocytes/macrophages was responsible for the impaired differentiation of monocytes in anti-inflammatory macrophages.  

We have identified 7 microRNAs, that differentiate monocytes of RA patients from those of healthy. Unfortunately, we could not confirm implication of new miR, except miR-155. Based on this and robust evidence of the pathogenic role of miR-155 in experimental and clinical arthritis, we proposed to test the therapeutic utility of targeting miR-155 in arthritis. 

This program research achieved 2 important goals: 

• We demonstrated that miR-155-driven defect of anti-inflammatory macrophage differentiation was also present in 2 pre-clinical models of RA: serum-transfer-arthritis (STA) and collagen-induce-arthritis (CIA) mice 
• We validated the therapeutic strategy using antagomiR-155 encapsulated in PEG-liposomes as compared to systemic delivery for decreasing arthritis incidence in CIA and STA mice. Moreover, PEG-liposomes were specific of monocytes and had no impact on other immune cells.  

Finally, injection of PEG-liposome containing antagomiR-155 with a small amount of antagomiR, we demonstrated a decrease of arthritis incidence, and a restoration of monocytes polarization in M2 macrophages in bone-marrow-derided-macrophages but also in mice synovial tissue. 

Overall, this research program contributed to a better understanding of the abnormalities of monocytes–macrophages in pathophysiology of RA. miR-155 inhibition is already in phase II in hematological malignancies with an apparent good safety profile. We confirm efficacy and specificity of antagomiR-155 encapsulated in PEG-liposomes in pre-clinical models of RA, with this approach specifically addressed to monocytes/macrophages could emerge as a novel and possible treatment for RA patients.

Both immunological and clinical issues addressed in this project are meant to answer unmet needs in the field of autoimmune diseases and pregnancy and the project is expected to have tangible benefits for patients with anti-SSA Abs. First, it will help to define better pre-counseling guidelines for women with anti-SSA Abs and tailored fetal monitoring. The development of predictive markers for CHB could alleviate the psychological burden associated to a very frequent ultrasound monitoring in women with a low risk of CHB. Ultimately, a pre-emptive treatment in women identified with a high risk of CHB could prevent mortality and long-term comorbidities. Patients are highly valued in this project given their central role in investigating the pathogenesis of CHB. The participation of a large number of mothers who had blood sampling early in pregnancy and at delivery (paired maternal-fetal samples) is a key element of the project. To associate actively PRPs to the project, the student will regularly communicate them the progress of his research and discuss the next steps. Direct communication with patients in PRPs meeting can also be initiated, as previously done by student. The construction of a long-term partnership will hopefully help disseminate the results to a large number of women with anti-SSA Abs and a wish to conceive.