Propionibacterium acnes infected intervertebral discs cause vertebral bone marrow lesions consistent with Modic changes.
Modic type I change (MC1) are vertebral bone marrow lesions adjacent to degenerated discs that are specific for discogenic low back pain. The etiopathogenesis is unknown, but occult discitis, in particular with Propionibacteria acnes (P. acnes), has been suggested as a possible etiology. If true, antibiotic therapy should be considered for patients with MC1. However, this hypothesis is controversial. While some studies report up to 40% infection rate in herniated discs, others fail to detect infected discs and attribute reports of positive cultures to contamination during sampling procedure. Irrespective of the clinical controversy, whether it is biologically plausible for P. acnes to cause MC1 has never been investigated. Therefore, the objective of this study was to test if P. acnes can proliferate within discs and cause reactive changes in the adjacent bone marrow. P. acnes was aseptically isolated from a symptomatic human L4/5 disc with MC1 and injected into rat tail discs. We demonstrate proliferation of P. acnes and up-regulation of IL-1 and IL-6 within three days of inoculation. At day-7, disc degeneration was apparent along with fibrotic endplate erosion. TNF-α immunoreactivity was enhanced within the effected endplates along with cellular infiltrates. The bone marrow appeared normal. At day-14, endplates and trabecular bone close to the disc were almost completely resorbed and fibrotic tissue extended into the bone marrow. T-cells and TNF-α immunoreactivity were identified at the disc/marrow junction. On MRI, bone marrow showed MC1-like changes. In conclusion, P. acnes proliferate within the disc, induce degeneration, and cause MC1-like changes in the adjacent bone marrow. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1447-1455, 2016.
Department of Orthopaedic Surgery, University of California San Francisco, 513 Parnassus Avenue, Suite-1164, San Francisco, 94143, California.
Stefan
S
Dudli
Department of Orthopaedic Surgery, University of California San Francisco, 513 Parnassus Avenue, Suite-1164, San Francisco, 94143, California.
Ellen
E
Liebenberg
Department of Radiology, University of California San Francisco, 185 Berry St., Suite 350, San Francisco, 94107, California.
Sergey
S
Magnitsky
Department of Laboratory Medicine, University of California San Francisco, 185 Berry St., Suite 290, San Francisco 94107, California.
Steve
S
Miller
Department of Orthopaedic Surgery, University of California San Francisco, 1500 Owens St., San Francisco, 94158, California.
Sibel
S
Demir-Deviren
Department of Orthopaedic Surgery, University of California San Francisco, 513 Parnassus Avenue, Suite-1164, San Francisco, 94143, California.
Jeffrey C
JC
Lotz
D000328:Adult; D000818:Animals; D001853:Bone Marrow / Q000473:pathology*; D005260:Female; D016908:Gram-Positive Bacterial Infections / Q000473:pathology*; D054884:Host-Pathogen Interactions; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000382:microbiology* / Q000473:pathology; D017116:Low Back Pain / Q000382:microbiology*; D008279:Magnetic Resonance Imaging; D000070614:Nucleus Pulposus / Q000378:metabolism; D011425:Propionibacterium acnes / Q000502:physiology*; D017207:Rats, Sprague-Dawley
Modic changes; Propionibacterium acnes; bone marrow; disc degeneration; low back pain