Evidence suggests that intervertebral disc degeneration (IVDD) can be induced by Propionibacterium acnes (P. acnes), although the underlying mechanisms are unclear. In this study, we analyzed the pathological changes in degenerated human intervertebral discs (IVDs) infected with P. acnes. Compared with P. acnes-negative samples, P. acnes-positive IVDs showed increased apoptosis of nucleus pulposus cells (NPCs) concomitant with severe IVDD. Then, a P. acnes-inoculated IVD animal model was established, and severe IVDD was induced by P. acnes infection by promoting NPC apoptosis. The results suggested that P.acnes-induced apoptosis of NPCs via the Toll-like receptor 2 (TLR2)/c-Jun N-terminal kinase (JNK) pathway and mitochondrial-mediated cell death. In addition, P. acnes was found to activate autophagy, which likely plays a role in apoptosis of NPCs. Overall, these findings further validated the involvement of P. acnes in the pathology of IVDD and provided evidence that P. acnes-induced apoptosis of NPCs via the TLR2/JNK pathway is likely responsible for the pathology of IVDD.

Background: The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease (COVID-19), has been declared a global pandemic. Identifying individuals whose infection can potentially become severe is critical to control the case fatality rate of COVID-19. However, knowledge of symptoms that are prognostic of COVID-19 severity is lacking. Objective: The objective of our study was to identify symptoms prognostic of COVID-19 infection severity. Methods: We analyzed documented symptoms, including fever, cough, fatigue, expectoration, sore throat, chest distress, headache, diarrhea, rhinorrhea, stuffed nose, nausea, vomiting, muscle or joint ache, shortness of breath, and their associations with disease severity using a case series, including 655 confirmed cases from January 23 to February 5, 2020 in Henan Province, China. We also analyzed the influence of individual characteristics, including age, gender, and comorbidities, on symptoms with prognostic value. Results: Fatigue (95% CI 0.141 to 0.334, P<.001), expectoration (95% CI 0.107 to 0.305, P<.001) and stuffed nose (95% CI –0.499 to –0.082, P=.006) were identified as the prognostic symptoms of COVID-19 patients from the multivariate analysis. Fever occurred in 603/655 (92.1%) of the patients but was not associated with disease severity. Fatigue accounted for 184/655 (28.1%) of the patients and was linearly associated with infection severity with statistical significance. Expectoration occurred in 169/655 (25.8%) patients in the cohort and was the sole prognostic factor for patients with cardiovascular complications, including hypertension. Shortness of breath, chest distress, muscle or joint ache, and dry cough, which occurred in 33 (5%), 83 (12.7%), 78 (11.9%), and 276 (42.1%) of the 655 patients, respectively, were significantly enriched among patients classified as severe. Stuffed nose and nausea were associated with favorable disease severity, especially among male patients. More female than male patients were documented as having muscle or joint ache. Headache was most enriched in patents aged 15 to 39 years, followed by those aged 40 to 64 years, with statistical significance. Conclusions: Fatigue and expectoration are signs of severe COVID-19 infection. Shortness of breath, chest distress, muscle or joint ache, and dry cough are prevalent in severe patients. Expectoration is commonly present in older individuals and patients with cardiovascular disorders, including hypertension. Shortness of breath is prognostic of severe infection in male patients. Stuffed nose and nausea are favorable prognostic factors of severe infection, especially among male patients.

Accumulating evidence suggests that Propionibacterium acnes (P. acnes) is a novel pathogenic factor promoting intervertebral disc degeneration (IVDD). However, the underlying mechanisms by which P. acnes induces IVDD have been unclear. In this study, we quantified the severity of IVDD, as well as the expressions of inducible nitric oxide synthase (iNOS)/nitric oxide (NO) and cyclooxygenase (COX‐2)/prostaglandin (PGE₂) in human intervertebral discs (IVDs) infected with P. acnes. Compared with P. acnes‐negative IVDs, P. acnes‐positive IVDs showed increased iNOS/NO and COX‐2/PGE₂ activity concomitant with more severe IVDD. In order to detect the potential correlation between iNOS/NO expression, COX‐2/PGE₂ expression, and IVDD, we developed a P. acnes‐induced IVDD rat model and found that the upregulation of iNOS/NO and COX‐2/PGE₂ was essential to the occurrence of P. acnes‐induced IVDD. This finding was supported by the fact that the inhibition of iNOS/NO and COX‐2/PGE₂ activity ameliorated IVDD significantly, as evidenced by restored aggrecan and collagen II expression both in vivo and in vitro. Mechanistically, we found that P. acnes induced iNOS/NO and COX‐2/PGE₂ expressions via a reactive oxygen species‐ (ROS‐) dependent NF‐κB cascade. Furthermore, NADPH oxidase participated in P. acnes‐induced ROS, iNOS/NO, and COX‐2/PGE₂ expressions. Overall, these findings further validated the involvement of P. acnes in the pathology of IVDD and provided evidence that P. acnes‐induced iNOS/NO and COX‐2/PGE₂ activation via the ROS‐dependent NF‐κB pathway is likely responsible for the pathology of IVDD.

Reactive oxygen species (ROS) are thought to have a strong correlation with a number of intervertebral disc (IVD) diseases. Here, we aimed to determine whether ROS represent an etiology of low back pain (LBP) during IVD degeneration. Thirty degenerated intervertebral disc samples were obtained from patients, and ROS levels were quantified using dihydroethidium (DHE) staining. The results suggested a significant correlation between the ROS level and the severity of LBP. Subsequently, a puncture‐induced LBP model was established in rats, and ROS levels significantly increased compared with those in the sham surgery group, accompanied with severe puncture‐induced IVD degeneration. In addition, when ROS levels were increased by H₂O₂ administration or decreased by NAC treatment, the rats showed increased or decreased LBP, respectively. Based on this evidence, we further determined that stimulation with H₂O₂ in nucleus pulposus cells (NPCs) in vivo or in vitro resulted in upregulation of substance P (SP), a peptide thought to be involved in the synaptic transmission of pain, and that the severity of LBP decreased when SP levels were increased by exogenous SP administration or neutralized via aprepitant treatment in the IVDs of rats. In conclusion, ROS are primary inducers of LBP based on clinical and animal data, and the mechanism involves ROS stimulation of NPCs to secrete SP, which is a critical neurotransmitter peptide, to promote LBP in IVDs. Therefore, reducing the level of ROS with specific drugs and inhibiting SP may be alternative methods to treat LBP in the clinic.

Purpose. Low-virulence anaerobic bacteria, especially thePropionibacterium acnes (P. acnes), have been thought to be a new pathogeny for a series of disc diseases. However, until now, there has been no histological evidence to confirm this link. The purpose of this study was to confirm the presence ofP. acnesin nonpyogenic intervertebral discs via histological observation.Method. Degenerated intervertebral discs were harvested from 76 patients with low back pain and/or sciatica but without any symptoms of discitis or spondylodiscitis. The samples were cultured under anaerobic conditions and then examined using 16S rDNA PCR to screen forP. acnes. Samples found to be positive forP. acneswere stained with hematoxylin-eosin (HE) and modified Brown-Brenn staining and observed under a microscope.Results. Here, 16 intervertebral discs were found to be positive forP. acnesvia 16S rDNA PCR and the prevalence was 21.05% (16/76). Among them, 7 samples had visible microbes stained with HE and modified Brown-Brenn staining. Morphological examination showed the bacteria to be Gram-positive and rod-shaped, so they were consideredP. acnes.Conclusion.P. acnesis capable of colonizing some degenerated intervertebral discs without causing discitis, and its presence could be further confirmed by histological evidence. Targeting these bacteria may be a promising therapy method for some disc diseases.