Biological changes in human B-cell line Ramos (RA.1) related to increasing doses of human parathyroid hormone

Abstract

Background: The etiopathogenesis of autoimmune diseases is multifactorial, including hormonal factors. Remission of autoimmunity has been observed following treatment for concomitant hyperparathyroidism. Additionally, patients with autoimmune diseases have shown increased expression of parathyroid hormone receptor (PTH1R) and altered distribution of B cells subsets. Hence, this study aims to evaluate potential mechanisms and in vitro effects of PTH stimulation on B lymphocytes. Methods: Using the human B-cell line Ramos (RA.1), various biological effects were evaluated with and without parathyroid hormone (PTH) stimulation at varying concentrations. Flow cytometry was employed to evaluate the phenotype of B lymphocytes based on IgD and CD38 expression, apoptosis induction via Annexin V and proliferation using CFSE. IgM production was quantified through ELISA, and Western blot analysis was performed to assess syk protein phosphorylation as an indicator of cell activation. Results: Ramos cells (RA.1) evidenced a statistically significant change in the phenotype under human PTH stimulation, demonstrating an increased proportion of germinal centre cells (Bm3-Bm4) when stimulated with high concentrations of PTH. Conclusions: The in vitro effects of PTH in B cells subsets align with previous findings of an altered phenotype in B lymphocytes expressing PTH1R among autoimmune disease patients, suggesting a potential role of this hormone in the pathophysiology of autoimmune diseases. However, further studies are necessary to elucidate the mechanisms by which PTH generates observed effects in B lymphocytes and to determine if PTH plays a role in autoimmunity.

Keywords

• Autoimmunity
• Autoimmune diseases
• B cells
• PTH
• Hyperparathyroidism