Integrated analysis of messenger RNA and microRNA in patients with community-acquired pneumonia associated sepsis (mRNA part)

Background: Community-acquired pneumonia (CAP) is defined as an acute lung infection involving the alveoli that occurs in a patient without recent health care exposure. A complication of CAP is severe sepsis, a syndrome of infection often accompanied by systemic inflammation and organ dysfunction. The aim of this study was to evaluate mRNA and miRNA in whole blood and to perform an integrative analysis to assess cellular signals that play a role in the pathogenesis of patients with CAP-associated sepsis. Methods: This was a prospective, observational, single-center study of patients transported to the Department of Traumatology and Acute Critical Medicine, Graduate School of Medicine, Osaka University. Patients with CAP-associated sepsis were analyzed. The diagnosis of pneumonia was made according to the clinical findings, including blood samples and chest computed tomography scan, and the diagnosis of sepsis followed the Sepsis-3 guidelines. Results: We included 14 critically ill patients with CAP-associated sepsis and 15 healthy control subjects (HCS). The median ages of the patient group and HCS were 78 and 55 years, and their body mass indexes were 22.8 and 21.7 kg/m2, respectively. All patients were treated at the critical care center, and 11 of the 14 patients received ventilatory management. All patients survived. These 14 patients met the diagnostic criteria of Sepsis-3 and were diagnosed as having CAP-associated sepsis. Of them, 6 patients met the diagnostic criteria for septic shock. RNA sequencing showed the number of genes with up:down (upregulated:downregulated) expression variation (false discovery rate [FDR] <0.05, |log2 fold change| >1.2) to be 1209:1461 for mRNA; 51:21 for microRNA; and 646:1274 for miRNA-targeted mRNA. Canonical pathway analysis using mRNA showed activation of the PD-1 and PD-L1 cancer immunotherapy signaling pathways and inhibition of the Th1 signaling pathway as well as that using miRNA-targeted mRNAs. Conclusions: Using integrated analysis of mRNA and miRNA, we elucidated for the first time, to our knowledge, that T-cell exhaustion occurred during the acute phase of CAP-associated sepsis and that miRNA regulated Th1 signaling and PD-1 and PD-L1 cancer immunotherapy signaling through the RNA interference action of mRNA.