The role of monocytic myeloid‐derived suppressor cells in the pathogenesis of endometriosis

Lung resided monocytic myeloid-derived suppressor cells contribute to premetastatic niche formation by enhancing MMP-9 expression

In cancer patients, the prevalence of myeloid-derived suppressor cells (MDSCs) is correlated with the degree of malignancy. In the present study, we investigated the role of circulating M-MDSCs in premetastatic niche formation using a mouse syngeneic tumor model and found that there was an increased frequency of M-MDSCs in the peripheral blood of tumor-bearing mice. M-MDSCs tracking and lung tissue histological analyses revealed that the malignant conditions promote the residence of circulating M-MDSCs and increased tumor cell arrest in the lungs. We further found that MMP-9 expression was increased in the circulating M-MDSCs and the administration of an MMP-9 inhibitor suppressed M-MDSCs transplantation-induced tumor cell arrest in the lung. Therefore, our findings suggest that the expansion of circulating M-MDSCs during tumor progression contributes to premetastatic niche formation by increasing MMP-9 expression.

CD4+/CD8+ mucosa-associated invariant T cells foster the development of endometriosis: a pilot study

BACKGROUND

Immune dysregulation is one of the mechanisms to promote endometriosis (EMS). Various T cell subpopulations have been reported to play different roles in the development of EMS. The mucosa-associated invariant T cell (MAIT) is an important T cell subset in the pathogenesis of various autoimmune diseases. Evidence has indicated that there are three functionally distinct MAIT subsets: CD4+, CD8+ and CD4/CD8-/- (double negative, DN) MAIT cells. Till now, the associations between endometriosis and MAIT have not been studied. Our research investigates different MAIT subpopulations in peripheral blood (PB) and peritoneal fluid (PF) from EMS patients.

METHODS

Thirty-two EMS patients and eighteen controls were included. PB and PF were collected. Tests of cytokines in plasma and PF were performed by ELISA kit. Characterisations of MAIT were done by flow cytometry. MAIT cells have been defined as CD3 + CD161 + Vα7.2+ cells. Based on CD4 and CD8 expression, they were divided into CD8⁺MAIT, CD4⁺MAIT and DN MAIT.

RESULTS

Enrichments of MAIT cells, especially CD4 and CD8 MAIT subsets were found. Moreover, CD8 MAIT cells had a high activation in the EMS group. EMS patients produced higher level of IL-8/12/17 as compared to these from controls. On the contrary, control patients exhibited an impressive upregulation of DN MAIT cells, however, these DN MAIT cells from controls showed a higher expression of PD-1. Lastly, we performed the relevance analysis, and discovered that the accumulation of PB MAIT cells positively correlated with an elevated level of serum CA125 production in EMS group.

CONCLUSION

These results suggest that different MAIT subsets play distinct roles in the progression of endometriosis.