Increase of Circulating Monocyte-Platelet Conjugates in Rheumatoid Arthritis Responders to IL-6 Blockage

Platelet-Derived Soluble CD40L and Its Impact on Immune Modulation and Anti-IL6R Antibody Treatment Outcome in Rheumatoid Arthritis

BACKGROUND

Platelets (PLTs) from healthy donors (HD) modulate T lymphocyte responses but PLTs from rheumatoid arthritis (RA) patients contribute to persistent systemic inflammation. This suggests that PLTs from RA patients and HD have different immunomodulatory effects.

METHODS

Using cell culture, flow cytometry, proteomics, and ELISA, we compared PLTs from HD and RA patients and their effects on T lymphocyte activation and cytokine production.

RESULTS

HD PLTs suppressed T lymphocyte proliferation and IFNγ and TNF production, while RA PLTs exhibited reduced suppressive capacity. In the presence of RA PLTs, IFNγ levels correlated with T lymphocyte proliferation, greater disease activity, and anti-citrullinated protein antibodies (ACPA). Proteomic analysis revealed that RA PLTs show upregulation of proteins linked to acute-phase response and complement activation. RA PLTs secreted higher levels of soluble CD40L (sCD40L) and PDGF-BB that correlated with enhanced IFNγ production. Seropositive RA patients had higher levels of sCD40L, and these levels were predictive of disease remission in RA patients treated with anti-IL6R. sCD40L was found to enhance T lymphocyte activation and to contribute to increased pro-inflammatory cytokine production.

CONCLUSIONS

This study highlights the diminished ability of RA PLTs to suppress T lymphocyte activation and that sCD40L can be a potential biomarker and therapeutic target in RA.

Platelet signaling in immune landscape: comprehensive mechanism and clinical therapy

Platelets are essential for blood clotting and maintaining normal hemostasis. In pathological conditions, platelets are increasingly recognized as crucial regulatory factors in various immune-mediated inflammatory diseases. Resting platelets are induced by various factors such as immune complexes through Fc receptors, platelet-targeting autoantibodies and other platelet-activating stimuli. Platelet activation in immunological processes involves the release of immune activation stimuli, antigen presentation and interaction with immune cells. Platelets participate in both the innate immune system (neutrophils, monocytes/macrophages, dendritic cells (DCs) and Natural Killer (NK) cells and the adaptive immune system (T and B cells). Clinical therapeutic strategies include targeting platelet activation, platelet-immune cell interaction and platelet-endothelial cell interaction, which display positive development prospects. Understanding the mechanisms of platelets in immunity is important, and developing targeted modulations of these mechanisms will pave the way for promising therapeutic strategies.

Changes in Adhesion and the Expression of Adhesion Molecules in PBMCs after Aneurysmal Subarachnoid Hemorrhage: Relation to Cerebral Vasospasm

Aneurysmal subarachnoid hemorrhage (aSAH) is a neurovascular disease produced by extravasation of blood to the subarachnoid space after rupture of the cerebral vessels. After bleeding, the immune response is activated. The role of peripheral blood mononuclear cells (PBMCs) in this response is a current subject of research. We have analysed the changes in PBMCs of patients with aSAH and their interaction with the endothelium, focusing on their adhesion and the expression of adhesion molecules. Using an in vitro adhesion assay, we observed that the adhesion of PBMCs of patients with aSAH is increased. Flow cytometry analysis shows that monocytes increased significantly in patients, especially in those who developed vasospasm (VSP). In aSAH patients, the expression of CD162, CD49d, CD62L and CD11a in T lymphocytes and of CD62L in monocytes increased. However, the expression of CD162, CD43, and CD11a decreased in monocytes. Furthermore, monocytes from patients who developed arteriographic VSP had lower expression of CD62L. In conclusion, our results confirm that after aSAH, monocyte count and adhesion of PBMCs increase, especially in patients with VSP, and that the expression of several adhesion molecules is altered. These observations can help predict VSP and to improve the treatment of this pathology.

Pathophysiology and stratification of treatment-resistant rheumatoid arthritis

Early diagnosis and timely therapeutic intervention are clinical challenges of rheumatoid arthritis (RA), especially for treatment-resistant or difficult-to-treat patients. Little is known about the immunological mechanisms involved in refractory RA. In this review, we summarize previous research findings on the immunological mechanisms of treatment-resistant RA. Genetic prediction of treatment-resistant RA is challenging. Patients with and without anti-cyclic citrullinated peptide autoantibodies are considered part of distinct subgroups, especially regarding long-term clinical prognosis and treatment responses. B cells, T cells and other immune cells and fibroblasts are of pathophysiological importance and are associated with treatment responses. Finally, we propose a new hypothesis that stratifies patients with RA into two subgroups with distinct immunological pathologies based on our recent immunomics analysis of RA. One RA subgroup with a favorable prognosis is characterized by increased interferon signaling. Another subgroup with a worse prognosis is characterized by enhanced acquired immune responses. Increases in dendritic cell precursors and diversified autoreactive anti-modified protein antibodies may have pathophysiological roles, especially in the latter subgroup. These findings that improve treatment response predictions might contribute to future precision medicine for RA.

Platelets-related signature based diagnostic model in rheumatoid arthritis using WGCNA and machine learning

Background and aim

Rheumatoid arthritis (RA) is an autoinflammatory disease that may lead to severe disability. The diagnosis of RA is limited due to the need for biomarkers with both reliability and efficiency. Platelets are deeply involved in the pathogenesis of RA. Our study aims to identify the underlying mechanism and screening for related biomarkers.

Methods

We obtained two microarray datasets (GSE93272 and GSE17755) from the GEO database. We performed Weighted correlation network analysis (WGCNA) to analyze the expression modules in differentially expressed genes identified from GSE93272. We used KEGG, GO and GSEA enrichment analysis to elucidate the platelets-relating signatures (PRS). We then used the LASSO algorithm to develop a diagnostic model. We then used GSE17755 as a validation cohort to assess the diagnostic performance by operating Receiver Operating Curve (ROC).

Results

The application of WGCNA resulted in the identification of 11 distinct co-expression modules. Notably, Module 2 exhibited a prominent association with platelets among the differentially expressed genes (DEGs) analyzed. Furthermore, a predictive model consisting of six genes (MAPK3, ACTB, ACTG1, VAV2, PTPN6, and ACTN1) was constructed using LASSO coefficients. The resultant PRS model demonstrated excellent diagnostic accuracy in both cohorts, as evidenced by area under the curve (AUC) values of 0.801 and 0.979.

Conclusion

We elucidated the PRSs occurred in the pathogenesis of RA and developed a diagnostic model with excellent diagnostic potential.