In patients with community-acquired pneumonia (CAP), serum interleukin-17 (IL-17) levels have been shown to predict the severity and prognosis of disease. A prospective cohort study was conducted between August 2019 and April 2021 among patients with CAP seen in the Department of Respiratory and Critical Care Medicine of Second Affiliated Hospital of Anhui Medical University, located in Anhui, China. Results of the analysis were published in BMC Pulmonary Medicine.

Recognizing that IL-17 is considered an attractive target for inflammatory responses in the body, the researchers sought to examine the relationship between serum IL-17 and the severity/prognosis of CAP among a cohort of patients. A total of 239 patients with CAP were enrolled in the present study, all of whom were eligible for the current research. Diagnostic criteria to be fulfilled by the participants included (1) chest radiography suggestive of either a new patchy infiltrate, leaf or segment consolidation, ground glass opacity, or interstitial change; (2) presence of one or more selected symptom groups (presence of cough, sputum production, and dyspnea; core body temperature >38.0° C, auscultatory findings of abnormal breath sounds and rales; or white blood cell counts of >10×109/L or <4×109/L); and (3) pneumonia that occurred in the community, rather than in a hospital. The average patient age was 61.09 years; 40.17% of the participants were female.

Serum IL-17 was detected with the use of enzyme-linked immunosorbent assays. The severity of disease was assessed via CAP severity scores, including CURB-65, CRB-65, Pneumonia Severity Index (PSI), SMART-COP, CURXO, and Acute Physiology and Chronic Health Evaluation II (APACHE II). The CURXO score was used to divide the participants into 2 groups — those with mild CAP and those with severe CAP — with those with severe disease needing treatment in the hospital intensive care unit (ICU).


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Levels of serum IL-17 gradually increased in line with the severity of a patient’s CAP. Per correlative analysis, serum IL-17 was associated with clinical physiologic indicators among individuals with CAP. Per logistic regression, serum IL-17 was positively associated with CAP severity scores.

The study also tracked prognostic outcomes among patients with CAP. Results of the study showed that IL-17 levels on hospital admission were increased significantly in patients with CAP who were admitted to the ICU, received mechanical ventilation, were treated with a vasoactive agent, had lengthier hospitals stays, or died (P <.01 for all). Cutoff concentrations of serum IL-17 were 60.29 ng/mL for hospital stays of 14 days or greater; 84.92 ng/mL for use of mechanical ventilation, 84.92 ng/mL for admission to an ICU, and 86.80 ng/mL for death.

The investigators concluded that IL-17 may be implicated in the pathophysiology processes of CAP. In the future, they added, it is likely that IL-17 will become an effective biomarker for the diagnosis, prognosis, and treatment of patients with CAP.

Disclosure: None of the study authors has declared affiliations with biotech, pharmaceutical, and/or device companies.  

Reference  

Feng CM, Wang XM, Li MD, et al. Serum interleukin-17 predicts severity and prognosis in patients with community acquired pneumonia: a prospective cohort study. BMC Pulm Med. Published online December 2, 2021. doi:10.1186/s12890-021-01770-6