EFFECTS OF THE PARATHORMONE RECEPTOR EXPRESSION ON B CELLS AND THE BIOLOGICAL EFFECTS OF THE HORMONE ON CELL FUNCTIONING IN AUTOIMMUNE DISEASES

Presenter
  • Gabriel J. Tobón (Colombia)
Lecture Time
12:25 - 12:31

Abstract

Background and Aims

Parathormone (PTH) has been clinically associated with autoimmune diseases but its pathophysiological impact has not been established. Our aim was to evaluate the expression of the PTH receptor (PTH1R) on B cells in patients with primary Sjögren’s Syndrome (pSS) and Systemic Lupus Erythematosus (SLE), and PTH effects on B cells in vitro.

Methods

We evaluated PTH1R expression on B cells and the receptor-expressing B cell subsets’ distribution (Bm1-Bm5) by flow cytometry in peripheral blood of SLE, pSS and healthy controls (HC). Analysis in vitro was performed in a B-cell line (Ramos) with PTH stimulus; effects on proliferation, apoptosis, and subpopulations were evaluated. We correlated PTH1R levels with ESSDAI and SLEDAI. Statistical analysis was performed using Kruskal Wallis and Spearman’s tests.

Results

We included 12 patients with SLE, 19 with pSS, and 20 HC. PTH1R expression on B-cells from SLE was 13% compared to pSS (4.4%), p=0,019; and HC (5%), p=0,013. Distribution of B cell subsets expressing PTH1R was significantly lower in Bm1 (23%), and higher in Bm2 (31.1%), and Bm2´ (6.4%) in pSS compared to HC (39%, 18%, 1.7%, respectively), p=0.010, 0.05, 0.028. Correlation between PTH1R levels and ESSDAI was r=0.511, p=0.026; SLEDAI was not correlated. Higher PTH concentrations tended to maintain B cells in Bm3-4 subset compared to unstimulated B cells that differentiated to eBm5 subset.

Conclusions

PTHR1 expression could be a useful biomarker in SLE and activity marker in pSS. PTH effects on B-cell subsets modulation suggest a potential role of the hormone in the pathophysiology of autoimmune diseases.

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