In people with community‑acquired pneumonia, those who are sicker have higher blood levels of the inflammation protein NLRP3 and lower levels of the antimicrobial peptide LL‑37. The combination of high NLRP3 and low LL‑37 predicts a worse chance of surviving 30 days.

This study aimed to determine the serum levels of NACHT, Leucine-rich repeat (LRR), and Pyrin (PYD) domains-containing Protein 3 (NLRP3) and cathelicidin LL-37, and investigate their prognostic significance in community-acquired pneumonia (CAP). The sample of this prospective study was composed of 76 consecutive patients with CAP. Demographic data and clinical characteristics were collected. Serum levels of NLRP3 and LL-37 were determined by ELISA. Spearman's analysis was used to evaluate the correlation between NLRP3 and LL-37. Association of NLRP3 and LL-37 with 30-day survival and mortality rates was assessed using the Kaplan-Meier curve and logistic regression analysis. Serum NLRP3 significantly increased whereas serum LL-37 significantly decreased in patients with severe CAP. Significant correlation was observed between serum NLRP3 and LL-37 in CAP patients. Patients with higher levels of NLRP3 and lower levels of LL-37 showed lower 30-day survival rate and higher mortality compared with those with lower NLRP3 and higher LL-37 levels. Severe CAP patients tend to present higher serum NLRP3 and lower serum LL-37, which might serve as potential biomarkers for CAP prognosis.