Defending the Homeland: Microbiome Molecules Provide Protection to Their Vertebrate Hosts

Abstract

Aim: The resident bacterial microbiome may shape and protect the health of vertebrate host. An array of molecules secreted by microbiome may contribute to the ecological stability of the microbiome itself. Material & methods: ELISA, radioactivity, immunofluorescence and cytokines measurements were used to observe the bioactivity and stability of colicin Ia level in oviparous and viviparous animal circulation. Results: Colicin Ia, a protein antimicrobial produced by Escherichia coli, is not present in animals at birth, but increases in concentration with the establishment of a stable gut microbiome and drops when the microbiome is experimentally disrupted. Colicin introduced in vivo is transported to tissues at concentrations able to prevent or eliminate bacterial infection. Conclusion: Our findings suggest an unexpected benefit provided by the presence of a resident microbiome in the form of active, circulating, bacterially-synthesized antimicrobial molecules.

Keywords::

• bacteriocin
• circulatory activity
• colicin
• enteromicrobiota
• host–bacterial interactions
• unexpected component of innate immunity

Supplementary data

To view the supplementary data that accompany this paper please visit the journal website at: www.tandfonline.com/doi/suppl/10.2217/fmb-2020-0008

Author contributions

XQ Qiu, KF Cao, XF Zhang, CY Tong, HL Ma, HM Xu, XL Zhang, Y Ma and RQ Li prepared colicin molecules, measured in vitro and in vivo killing activity and did immunolabeling/fluorescent/pathology assays; Z Zou carried out cytokine assay.

Acknowledgments

The authors would like to acknowledge the help and scientific critique of H Li, CY Jiang, RY Zhu, T Lei, BR Zhu, YD Wang, R Dorit, L Schwartz and S Roy during the preparation of this manuscript. The authors would also like to acknowledge the help of S Yang, X Zhang, C Zhang, L Jiang, F Meng, C Duan, S Liang, S Xu, T Liu, W Wang, J Li, F Feng and Y Zuo in animal operations and ELISA assays, immunoblotting, antibody-affinity column and serum colicin purification. Michael Cynamon, Prof. of Infectious Disease, VA Medical Center and SUNY Upstate Medical University, Syracuse, USA, provided linguistic corrections to the manuscript.

Financial & competing interests disclosure

This work was supported by the National Science and Technology Major Projects of New Drugs 2012ZX09103301-024 and 2015ZX09102007-014, National High Technology Research and Development Program of China 2011AA10A214, Beijing Municipal Science & Technology Commission Z111100067311012 and Z131100002713010 and Administrative Committee of Zhongguancun Haidian Science Park K20110135Z to X.-Q. Qiu and R.-Q. Li. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No funded writing assistance was utilized in the production of this manuscript.

Ethical conduct of research

All in vivo protocols were approved by the Institutional Animal Care and Use Committee of Sichuan University and Project of Sichuan Animal Experimental Committee, License 045, the Institutional Animal Care and Use Committee of JOINN Laboratories and Beijing Municipal Science & Technology Commission License SYXK (Jing) 2009-0024, China.

Data & material availability

All data and material are available from Lab. of Biomembrane & Membrane Proteins, West China Hospital, Sichuan University, Xiao-Qing Qiu ([email protected]).

Additional information

Funding

This work was supported by the National Science and Technology Major Projects of New Drugs 2012ZX09103301-024 and 2015ZX09102007-014, National High Technology Research and Development Program of China 2011AA10A214, Beijing Municipal Science & Technology Commission Z111100067311012 and Z131100002713010 and Administrative Committee of Zhongguancun Haidian Science Park K20110135Z to X.-Q. Qiu and R.-Q. Li. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.