Your new experience awaits. Try the new design now and help us make it even better

ORIGINAL RESEARCH article

Front. Cell. Infect. Microbiol.

Sec. Adaptive immunity in infection

Volume 15 - 2025 | doi: 10.3389/fcimb.2025.1652116

This article is part of the Research TopicExpanded Genus Brucella: from Taxonomy to Clinical Manifestations and Diagnosis ChallengesView all 16 articles

Siglec-9 acts as an immune checkpoint marker on MDSCs in Brucella Infection

Provisionally accepted
Huidong  ShiHuidong Shi1Xinxin  QiXinxin Qi1Kaiyu  ShangKaiyu Shang1Tingting  TianTingting Tian1Jianbing  DingJianbing Ding2Mingzhe  LiMingzhe Li2Ruixue  XuRuixue Xu2Fuling  PuFuling Pu2Junyu  KuangJunyu Kuang2Yuejie  ZhuYuejie Zhu1*Fengbo  ZhangFengbo Zhang1*
  • 1The First Affiliated Hospital of Xinjiang Medical University, Urumqi, China
  • 2Xinjiang Medical University, Urumqi, China

The final, formatted version of the article will be published soon.

Background: Brucellosis is a zoonotic disease that is widely prevalent in the Xinjiang region of China. Once it progresses to a chronic stage, it can lead to significant complications. Immune checkpoints markers on Myeloid-derived suppressor cells (MDSCs) may lead to the chronic stage of the disease. This study analyzed the changes in MDSCs, immune checkpoints markers and cytokines in the patients with acute and chronic Brucella infections and after antibiotic treatment, to explore their roles and provide new ideas for future clinical treatment. Methods: A total of 37 patients with acute brucellosis infection (ABI) and 46 patients with chronic brucellosis infection (CBI) and 43 healthy controls (HC) subjects were enrolled. Flow cytometry was used to detect the expression of MDSCs 、 Siglec-9+MDSCs 、PD-1+MDSCs and Tim-3+MDSCs before and after antibiotic treatment. In addition, ELISA was used to measure the levels of cytokines and the changes in IL-6 and Arg-1of them were assessed again after antibiotic treatment. Results: Our study found that the levels of MDSCs in the patients significantly increased, with CBI patients exhibiting higher levels than ABI patients. The cytokines showed varying degrees of elevation. Furthermore, after antibiotic treatment, the levels of MDSCs、Siglec-9+ MDSCs、PD-1+ MDSCs and Tim-3+ MDSCs in effective treatment patients significantly decreased. In contrast, the levels of MDSCs in ineffective treatment patients increased, while there were no significant differences in PD-1+ MDSCs and Tim-3+ MDSCs levels compared to before treatment. Notably, the levels of Siglec-9+MDSCs in ineffective treatment showed a significant increase. In the ineffective treatment patients, the serum levels of Arg-1 and IL-6 both increased compared to before treatment. Correlation analysis revealed a positive correlation in ineffective treatment patients between serum Arg-1 levels and MDSCs, as well as Siglec-9+ MDSCs levels, while no correlation was observed between IL-6 levels and immune cell parameters. Conclusion: MDSCs are increased in both ABI and CBI. Siglec-9 acts as an immune checkpoint on MDSCs in patients with ineffective treatment responses. Therefore, Siglec-9 represents a potential prognostic marker for Brucella infection. Ongoing research on prognostic markers of brucellosis is promising, and further clinical studies are warranted to validate these findings.

Keywords: Brucellosis, MDSCs, PD-1, TIM-3, Siglec-9, Cytokines

Received: 23 Jun 2025; Accepted: 02 Oct 2025.

Copyright: © 2025 Shi, Qi, Shang, Tian, Ding, Li, Xu, Pu, Kuang, Zhu and Zhang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Yuejie Zhu, 115127149@qq.com
Fengbo Zhang, zfb131@163.com

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.