Human intervertebral discs harbour a unique microbiome and dysbiosis determines health and disease

• Published in: European spine journal Vol. 29; no. 7; pp. 1621 - 1640
• Main Authors: Rajasekaran, Shanmuganathan, Soundararajan, Dilip Chand Raja, Tangavel, Chitraa, Muthurajan, Raveendran, Sri Vijay Anand, K. S., Matchado, Monica Steffi, Nayagam, Sharon Miracle, Shetty, Ajoy Prasad, Kanna, Rishi Mugesh, Dharmalingam, K.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-07-2020; Springer Nature B.V
• Subjects: Abundance; Bacteria; Biodiversity; Dysbacteriosis; Etiology; Intervertebral discs; Magnetic resonance imaging; Medicine; Medicine & Public Health; Microbiomes; Neurodegeneration; Neurosurgery; Organ donors; Original Article; Pathogens; Propionibacterium acnes; Skin; Spine (lumbar); Sterility; Surgical Orthopedics; Inflammaging; Sub-clinical infection; Dysbiosis; Disc degeneration; Microbiome
• ISSN: 0940-6719; 1432-0932
• DOI: 10.1007/s00586-020-06446-z

Background
To document the role of sub-clinical infections in disc disorders and investigate the existence of microbiome in intervertebral discs (IVD).
Methods
Genomic DNA from 24 lumbar IVDs [8—MRI normal discs (ND) from brain dead yet alive organ donors, 8—disc herniation (DH), 8—disc degeneration (DD)] was subjected to 16SrRNA sequencing for profiling the diversity of human disc microbiome in health and disease. The disc microbiome was further compared to established human gut and skin microbiomes.
Results
All healthy MRI normal discs from brain dead yet alive organ donors also had a rich bacterial presence. A total of 424 different species (355-ND, 346-DD, and 322-DH) were detected, with 42.75% OTUs being classified at kingdom level, 44% at the phylum level, 22.62% at genus level, and 5.5% at species level. Varying biodiversity and abundance between healthy and diseased discs were documented with protective bacteria being abundant in normal discs, and putative pathogens abundant in DD and DH.
Propionibacterium acnes
had a similar but lower abundance to other pathogens in all three groups ND (3.07%), DD (3.88%), DH (1.56%). Fifty-eight bacteria were common between gut and IVD microbiomes, 29 between skin and IVD microbiomes, and six common to gut/skin/IVD.
Conclusion
Our study challenges the hitherto concept of sterility in healthy IVD and documented a microbiome even in MRI normal healthy discs. The varying abundance of bacteria between ND, DD, and DH documents ‘dysbiosis’ as a possible etiology of DD. Many known pathogens were identified in greater abundance than
Propionibacterium acnes,
and there was evidence for the presence of the gut/skin/spine microbiome axis.