Longitudinal associations between serum IL-34 with severity and prognosis in community-acquired pneumonia patients

• Published in: Respiratory investigation 2024-03, Vol.62 (2), p.223-230
• Main Authors: Tang, Fei, Hou, Xue-Feng, Cheng, Yu, Liu, Ying, Sun, Jing, Liu, Hong-Yan, Lv, Li-Ping, Fu, Lin
• Format: Article
• Language: English
• Subjects: Community-acquired pneumonia; IL-34; Inflammation; Prognosis; Severity
• ISSN: 2212-5345; 2212-5353
• DOI: 10.1016/j.resinv.2023.12.008

Interleukin-34 (IL-34) is a hematopoietic cytokine and a ligand of colony-stimulating factor 1 receptor (CSF-1R). Numerous studies have demonstrated that IL-34 is involved in several inflammatory diseases. Nevertheless, the role of IL-34 is obscure in community-acquired pneumonia (CAP) patients. This research aimed to assess the associations of serum IL-34 with severity and prognosis in CAP patients through a longitudinal study. CAP patients and healthy volunteers were recruited. Peripheral blood samples were collected. Serum IL-34 and inflammatory cytokines were tested by enzyme linked immunosorbent assay (ELISA). Demographic characteristics and clinical information were acquired through electronic medical records. Serum IL-34 was elevated in CAP patients compared with healthy volunteers. The content of serum IL-34 was gradually upregulated with increased CAP severity scores. Mixed logistic and linear regression models suggested that serum IL-34 elevation was associated with increased PSI and SMART-COP scores. Correlative analysis found that serum IL-34 was positively correlated with inflammatory cytokines among CAP patients. A longitudinal study indicated that higher serum IL-34 at admission elevated the risks of mechanical ventilation and death during hospitalization. Serum IL-34 had a higher predictive capacity for death than CAP severity scores. There are prominently positive dose-response associations between serum IL-34 at admission with the severity and poor prognosis, suggesting that IL-34 is implicated in the occurrence and development of CAP. Serum IL-34 may serve as a biomarker to forecast disease progression and poor prognosis in CAP patients.