Transcriptomic Reanalysis Reveals Complement, Circadian, and Toll-Like Receptor Signaling Remodeling in Lactiplantibacillus plantarum-Induced Innate Immune Memory in Human Monocytes

Abstract

The commensal bacterium Lactiplantibacillus plantarum is recognized for its ability to cause a state of innate immune memory in monocytes, characterized by the tolerogenic phenotype and lowered pro-inflammatory responses. This study provides an extensive re-examination of the transcriptomic dataset originating from human CD14 + monocytes primed with live or heat-killed L. plantarum (GSE159496). Using a computational approach, 1,954 differentially expressed gene calls that corresponded to 1,397 unique genes were obtained through three pairwise comparisons. In addition, several novel biological pathways that were not investigated in the original study were discovered. Priming with live L. plantarum resulted in a marked downregulation of the complement system (12.5% decrease in its module score, p < 0.001), indicating an important mechanism of immune evasion. Additionally, a significant alteration of the circadian rhythm pathway was revealed, indicating its connection to metabolic time management in sustaining long-term immune tolerance. Toll-like receptor (TLR) signaling was coordinately repressed, with 17 pathway genes—including the receptors TLR2 and TLR8—significantly downregulated in live primed cells (p.adjust = 3.0 × 10–6 ). Other significantly modulated novel pathways included a downregulation of glycosylation and post-translational modifications (−13.2%, p < 0.01) and an upregulation of amino acid sensing/mTOR signaling (+11%, p < 0.001) and xenobiotic detoxification (+12%, p < 0.01). These findings point to a multi-layered adaptive response where L. plantarum not only dampens canonical inflammatory signaling but also actively remodels cellular processes related to pathogen recognition, metabolic sensing, and stress responses. This reanalysis provides a more granular model of probiotic-induced immune memory.

Received: 24 June 2026 | Revised: 6 August 2026 | Accepted: 15 September 2026

Conflicts of Interest

The authors declare that they have no conflicts of interest to this work.

Data Availability Statement

The data analyzed in this study are publicly available in the NCBI Gene Expression Omnibus under accession GSE159496: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE159496. This study reanalyzed existing data and generated no new experimental data. The analysis scripts are deposited at https://github.com/ahmedalfahad/L-plantarum-innate-memory-reanalysis.

Author Contribution Statement

Hanan Yassin Muhsin: Conceptualization, Methodology, Software, Formal analysis, Investigation, Data curation, Writing – original draft, Writing – review & editing, Visualization, Project administration. Azhaar Raheem Hussein AL-Fartwsy: Methodology, Validation, Formal analysis, Investigation, Data curation, Writing – review & editing. Amenah Hussein Mousa: Validation, Investigation, Data curation, Writing – review & editing, Visualization. Ahmed AbdulJabbar Suleiman: Conceptualization, Software, Validation, Resources, Writing – original draft, Supervision, Project administration.