Transcriptomic Profiling Reveals Candidate lncRNA-S100-GPCR Co-Expression Networks in Lungs of Piglets Infected with...

Glaesserella parasuis (G. parasuis) is a major respiratory pathogen in piglets, but the regulatory mechanisms underlying its induced pulmonary inflammation remain poorly understood. In this study, whole-transcriptome sequencing was carried out on lung tissues from colostrum-deprived piglets with mild and severe serotype 5 G. parasuis infection and healthy controls. Differential expression (DE) analysis revealed 299 nominally DE mRNAs and 408 nominally DE lncRNAs in the mild group, increasing to 625 and 1193, respectively, in the severe group. Ingenuity Pathway Analysis identified the S100 family signaling pathway as a core inflammatory module predicted to be activated across both infection grades, with its transcriptional involvement expanding from 8 genes in mild infection to 42 genes in severe infection. Notably, G-protein-coupled receptors (GPCRs) accounted for nearly half (19/42) of the S100-associated DE genes in severe infection, covering multiple functional categories including chemokine receptors, lipid mediator receptors, and metabotropic receptors, suggesting systemic activation of the GPCR family in severe inflammation. Weighted gene co-expression network analysis identified multiple lncRNA candidates, among which two-LOC110256217 and LOC110259349-showed severity-associated connectivity patterns and were selected for further validation. Following G. parasuis infection, time-series RT-qPCR in 3D4/21 cells confirmed their co-expression with corresponding mRNAs and revealed distinct temporal patterns, suggesting their potential differential involvement at early and late stages of the inflammatory response. Collectively, these findings identify a putative lncRNA-S100-GPCR-associated inflammatory module linked to pulmonary inflammation in G. parasuis infection, providing a transcriptomic resource and candidate lncRNA-mRNA pairs for further functional studies and investigation into host resilience. Given the limited sample size (n = 3 per group), these findings should be considered exploratory and warrant validation in larger cohorts.