Peptidoglycan from probiotic L. rhamnosus enhanced avian defensin 9 expression and Salmonella killing in chicken cells without inflammatory cytokine production.
Zero inflammationprobiotic peptidoglycan enhanced antimicrobial peptide defense without any inflammatory cytokine production
What the researchers found
Peptidoglycan from probiotic L. rhamnosus MLGA produced a dose-dependent increase in avian beta-defensin 9 (AvBD9) mRNA in multiple immune cell types (PBMCs, splenocytes, thymocytes, hepatocytes) and in chicken embryo intestinal explants (jejunum, ileum, cecum).
Functional validation: lysates from peptidoglycan-treated PBMCs and splenocytes showed increased ability to inhibit Salmonella Enteritidis growth, confirming the induced defensin was biologically active.
Critically, this defensin induction occurred without activating pro-inflammatory cytokines IL-1beta, IL-8, and IL-12p40. When peptidoglycan was digested with lysozyme, the hydrolysate actually suppressed these inflammatory cytokines.
In contrast, peptidoglycan from pathogenic S. aureus reduced AvBD9 expression in PBMCs and splenocytes, showing pathogen-derived vs probiotic-derived cell wall material has opposite effects on defensin production.
Why it matters
Antibiotics in poultry farming drive resistance. Probiotics can enhance natural defense, but the mechanism was unclear. This study shows a specific probiotic component (peptidoglycan) boosts antimicrobial peptide production without causing harmful inflammation. This precision is ideal: kill pathogens without damaging the gut.
The numbers in context
AvBD9 up in all cell types; Salmonella killing enhanced; no IL-1β/IL-8/IL-12p40; S. aureus PG had opposite effect
How the study worked
In vitro and ex vivo study using chicken immune cells and embryonic intestinal explants. Peptidoglycan was purified from L. rhamnosus MLGA and S. aureus. AvBD9 expression measured by qPCR. Antimicrobial function tested by Salmonella growth inhibition assays. Cytokine expression (IL-1beta, IL-8, IL-12p40) monitored to assess inflammatory response.
Who was studied
Chicken PBMCs, splenocytes, thymocytes, hepatocytes; embryo intestinal explants
What this study cannot tell us
Tested in chicken cells and embryonic explants, not in live chickens challenged with pathogens. The specific structural features of probiotic vs pathogenic peptidoglycan that explain their opposite effects were not identified. Only one probiotic species and one pathogen were compared. The dose-response relationship in live birds may differ from cell culture.
How to read the evidence
Moderate evidence from in vitro and ex vivo studies using multiple cell types and intestinal explants. Functional Salmonella killing confirmed.
When this study was published
Published in 2020. Probiotic-based antimicrobial peptide enhancement is an active research area in poultry science.
The bigger picture
Antibiotics in poultry farming drive resistance. This study shows a specific probiotic component (peptidoglycan) boosts natural antimicrobial defenses without causing inflammation. This selective immune enhancement could replace prophylactic antibiotics in poultry production.
Questions still open
- What structural differences between probiotic and pathogenic peptidoglycan explain their opposite effects?
- Would this translate to disease protection in live chicken challenge studies?
- Could purified peptidoglycan be added to feed as an alternative to whole probiotics?
Common questions
Why does probiotic peptidoglycan behave differently from pathogenic peptidoglycan?
Could this reduce antibiotic use in chicken farming?
Read the original research
Peptidoglycan derived from Lactobacillus rhamnosus MLGA up-regulates the expression of chicken β-defensin 9 without triggering an inflammatory response.
Innate immunity, 26(8), 733-745
Citation
Huang, Juan; Li, Junhui; Li, Qiufen; Li, Lin; Zhu, Nianhua; Xiong, Xiaowen; Li, Guanhong. (2020). Peptidoglycan derived from Lactobacillus rhamnosus MLGA up-regulates the expression of chicken β-defensin 9 without triggering an inflammatory response.. Innate immunity, 26(8), 733-745. https://doi.org/10.1177/1753425920949917