ER-stressed MSC displayed more effective immunomodulation in RA CD4⁺CXCR5⁺ICOS⁺ follicular helper-like T cells through higher PGE2 binding with EP2/EP4

Abstract

Objectives: To analyze the further immunomodulatory effects of endoplasmic reticulum (ER)-stressed umbilical cord-derived mesenchymal stem cells MSCs (UC-MSCs) on rheumatoid arthritis (RA) CD4⁺CXCR5⁺ICOS⁺ T (follicular helper-like T, Tfh) cells.

Methods: MSCs were isolated from umbilical cord and surface markers were identified by flow cytometry. CD4⁺ T cells were purified from RA patients’ peripheral blood mononuclear cells (PBMCs) using immunomagnetic beads. Thapsigargin (Tg)-stimulated or unstimulated MSCs were co-cultured with RA CD4⁺ T cells. CD4⁺CXCR5⁺ICOS⁺ T cells were analyzed with fluorescence activating cell sorter (FACS) and major soluble factors secreted by MSCs were detected by qRT-PCR as well as ELISA. Receptors of prostanoid E2 (PGE2), known as EP1-4, on CD4⁺ T cells were tested with RT-PCR and FACS. Proportion of CD4⁺CXCR5⁺ICOS⁺ T cells was determined after EP2/EP4 antagonists and anti-IL-6R antibody was added into co-cultured system, respectively.

Results: ER-stressed MSCs further down-regulated peripheral CD4⁺CXCR5⁺ICOS⁺ T cells compared with Tg-stimulated MSCs and CD4⁺ T co-cultured group. PGE2 and IL-6 increased obviously in the supernatants. EP2/EP4 could be detected on CD4⁺ T cells and frequencies of CD4⁺CXCR5⁺ICOS⁺ T cells were upregulated when EP2 and/or EP4 antagonists rather than anti-IL-6R antibody were added.

Conclusions: ER-stressed MSCs exhibited better inhibition effect on RA CD4⁺CXCR5⁺ICOS⁺ T cells by releasing PGE2, indicating the immunosuppressive effect of MSCs could be enhanced by induction of ER stress.

Keywords:

• CD4⁺CXCR5⁺ICOS⁺ T cells
• endoplasmic reticulum stress
• mesenchymal stem cells
• prostaglandin E2
• rheumatoid arthritis

Compliance with ethical standards

Experiments were approved by the ethical committee of the Second Affiliated Hospital of Dalian Medical University. All study subjects signed written informed consent before participating in the study.

Conflict of interest

None

Additional information

Funding

This work was supported by National Natural Science Foundation of China (no. 81671606); Natural Science Foundation of LiaoNing Province (no. 20180550789); a Special Grant for Translational Medicine, Dalian Medical University (no. 2015010); College Scientific Research Project of Education Department of Liaoning Province (no. LQ2017007); Distinguished Professor of Liaoning Province (Liao taught (2018–2020)).