ORIGINAL RESEARCH article
Front. Med.
Sec. Geriatric Medicine
Treg/Th17 Imbalance and Its Association with Frailty in Elderly Patients with Community-Acquired Pneumonia
Yiming Yuan 1
Chulun Zeng 2
Qiuyu han 3
1. West China Hospital of Sichuan University, Chengdu, China
2. People's Hospital of Chongqing Liangjiang New Area, Chongqing, China
3. The Third Affiliated Hospital of Chongqing Medical University, Chongqing, China
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Abstract
Objective: To investigate the potential role of Treg/Th17 imbalance in frail elderly patients with community-acquired pneumonia (CAP) by analyzing the clinical characteristics of elderly CAP patients, along with the proportions of regulatory T (Treg) cells and helper T (Th17) cells 17, and related cytokine levels. Methods: A total of 61 hospitalized CAP patients aged ≥65 years were continuously enrolled from June 2021 to January 2022. Frailty status was assessed using the FRAIL scale, and patients were divided into a frail group (n=33) and a non-frail group (n=28). General demographic data, laboratory test results, Charlson Comorbidity Index (CCI), Pneumonia Severity Index (PSI), and hospitalization outcomes were collected. The proportions of peripheral blood Treg and Th17 cells were measured, along with the serum levels of TGF-β, IL-10, and IL-17A. Results: The frail group exhibited older age, more comorbidities, more severe illness, poorer prognosis, longer hospital stays, and higher treatment costs compared to the non-frail group. Additionally, the frail group had significantly higher proportions of Treg cells and Treg/Th17 ratios, as well as higher TGF-β levels and lower IL-17A levels (P < 0.05). Correlation analysis showed a positive relationship between TGF-β levels and Treg proportions, and between IL-17A levels and Th17 proportions. After adjusting for confounding factors, frailty remained an independent factor influencing the elevated Treg/Th17 ratio. Logistic regression analysis indicated that advanced age, high CCI score, high Treg/Th17 ratio, low serum albumin, and female gender were independent risk factors for frailty in elderly CAP patients. Conclusion: Frail elderly CAP patients exhibit immune imbalance characterized by elevated Treg proportions and Treg/Th17 ratios, which may be associated with their poor prognosis and suggests potential value for immune-targeted interventions. The dysregulation of cytokines TGF-β and IL-17A aligns with the changes in Treg/Th17 proportions, potentially playing a role in the regulatory mechanisms of frailty-related immune imbalance.
Summary
Keywords
Community-acquired pneumonia, cytokine, Frailty, Th17 Cells, Treg cells
Received
31 December 2025
Accepted
17 February 2026
Copyright
© 2026 Yuan, Zeng and han. 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: Yiming Yuan
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