Background & Aims

Chronic posttraumatic musculoskeletal pain (CPMP) is a common outcome of trauamatic stress exposure (TSE)[1], yet few interventions are available to prevent/treat CPMP[2-4]. One barrier to novel therapeutic development for CPMP is an incomplete understanding of mechanisms via which promising drug candidates reduce pain. We recently showed that inhibition of the key regulator of the glucocorticoid stress response, FKBP51, reduces CPMP-like behavior in a rat model of TSE[5]. Further, the duration of reduction in CPMP-like behavior depended on timing of FKBP51 inhibition relative to TSE.[5] In the current study, we aimed to 1) understand how TSE alters the transcriptional landscape across body tissues over time, 2) determine the mechanism through which FKBP51 inhibition prevents CPMP-like behavior following TSE, and 3) identify why FKBP51 inhibition is most effective at reducing pain early following TSE.

Methods

Male Sprague Dawley rats (n=6 per group) were exposed to the single prolonged stress protocol, a well validated model of TSE[6]. At 2-, 24-, and 72-hours following TSE and in TSE-unexposed control rats, brain and body tissues (right and left hippocampus, amygdala, hypothalamus, spine, dorsal root ganglion [DRG], heart, and gastrocnemius musle) were collected, RNA isolated, and mRNA sequenced. RNA transcripts from each tissue and timepoint were analyzed for differential gene expression using DESeq2. Based on these data, top/common differentially expressed genes were identified as well as temporal patterns of gene expression. Such transcriptional changes were then compared to animals treated with a potent and specific inhibitor of FKBP51, SAFit2[7]. Blood-based corticosterone levels were also assayed after TSE and SAFit2 treatment.

Results

The most differentially expressed genes (vs control) were observed 2-hours post-TSE (10% of detected transcripts averaged across tissues, vs 6% and 5% at 24- and 72-hours). At the 2-hour timepoint, muscle tissue showed the greatest number of differentially expressed gene transcripts (398 mRNA). Interestingly, Fkbp5 (the gene encoding FKBP51) was strongly and statistically significantly increased in mRNA expression across all tissues analyzed 2-hours post-TSE(p<0.001, log2foldchange>1.14). Bioinformatic analyses showed time-dependent changes in stress, circadian, and proinflammatory pathways. (Full gene expression, pathway, and molecular results, including those from experiments with early postratumatic inhibiton of FKBP51, will be presented at the World Congress meeting.) Finally, we show that TSE causes a robust (6.5x) yet acute increase in serum corticosterone levels 3-minutes following TSE (p<0.0001) that resolved by 24 hours post-TSE.

Conclusions

TSE leads to robust time-dependent transcriptional changes across peripheral and nervous system tissues. Fkbp5 and glucocorticoid stress axis signaling are highly susceptible to TSE and are most dysregulated in the early aftermath of TSE. This study preliminarily suggests that inhibition of FKBP51 early following TSE may prevent CPMP development by blocking stress, circadian, and inflammatory signaling pathways that are activated by TSE. Further molecular studies are needed to identify causal mechanisms of CPMP prevention via FKBP51 inhibition and to validate across age, sex, strain, and behavioral pain assays.

References

1.SA McLean, et al., The development of persistent pain and psychological morbidity after motor vehicle collision: integrating the potential role of stress response systems into a biopsychosocial model. Psychosomatic medicine, 2005.
2.ML Barnett, et al., Opioid-Prescribing Patterns of Emergency Physicians and Risk of Long-Term Use. The New England journal of medicine, 2017. 10.1056/NEJMsa1610524.
3.FL Beaudoin, et al., Persistent pain after motor vehicle collision: comparative effectiveness of opioids versus non-steroidal anti-inflammatory drugs prescribed from the emergency department–a propensity matched analysis. Pain, 2017.
4.C Le Roy, et al., Endogenous opioids released during non-nociceptive environmental stress induce latent pain sensitization Via a NMDA-dependent process. The Journal of Pain, 2011.
5.BJ Wanstrath, et al., Duration of Reduction in Enduring Stress-Induced Hyperalgesia Via FKBP51 Inhibition Depends on Timing of Administration Relative to Traumatic Stress Exposure. J Pain, 2022. 10.1016/j.jpain.2022.02.007.
6.S Yamamoto, et al., Single prolonged stress: toward an animal model of posttraumatic stress disorder. Depression and anxiety, 2009.
7.V Buffa, et al., Analysis of the Selective Antagonist SAFit2 as a Chemical Probe for the FK506-Binding Protein 51. ACS Pharmacol Transl Sci, 2023. 10.1021/acsptsci.2c00234.

Presenting Author

Lauren A. McKibben

Poster Authors

Lauren McKibben

PhD

University of North Carolina at Chapel Hill

Lead Author

E-mail

Samuel McLean

MD MPH

The University of North Carolina at Chapel Hill

Lead Author

E-mail

Ying Zhao

MPH MS

The University of North Carolina at Chapel Hill

Lead Author

E-mail

Roxana Florea

University College London

Lead Author

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Meghna Iyer

The University of North Carolina at Chapel Hill

Lead Author

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Jacqueline Mickelson

University of North Carolina at Chapel Hill

Lead Author

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Sandrine M Geranton PhD

University College London

Lead Author

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Felix Hausch

PhD

Technische Universität Darmstadt

Lead Author

E-mail

Sarah Linnstaedt

PhD

The University of North Carolina at Chapel Hill

Lead Author

E-mail

Topics

  • Mechanisms: Biological-Molecular and Cell Biology