Acute Inflammatory Responses Needed to Resolve Chronic Pain Save

Science Translational Medicine has published results of a Canadian study of low back pain (LBP) suggests that pain control by anti-inflammatory treatments might have negative effects on pain duration and may be counterproductive for long-term pain outcomes.

A study of 98 patients with acture LBP were studied using transcriptome-wide analysis in peripheral immune cells at presentation and after 3 months. Parisien et showed that neutrophil activation–dependent inflammatory genes were up-regulated in subjects with resolved pain, whereas no changes were observed in patients with persistent pain

Transcriptomic changes were compared between cohorts whose pain either resolved or persisted at 3 months.

• LBP resolved cohort: they found thousands of dynamic transcriptional changes over 3 months
• LBP persisted cohort: no transcriptional changes seen in those with persistent pain.

They found that transient neutrophil-driven up-regulation of inflammatory responses was important to resolution and protective against transitioning to chronic persistent pain.

In other experiments looking at mouse pain assays, early treatment with a steroids or NSAIDs also led to prolonged pain despite being analgesic in the short term; but this prolongation was not observed with other analgesics. Moreover, depletion of neutrophils delayed resolution of pain in mice and injecting peripheral neutrophils or S100A8/A9 proteins prevented long-lasting pain induced by anti-inflammatory drugs.

Lastly, data on patient LBP from the UK Biobank identified NSAID use as a risk factor for pain persistence.

Despite early benefits of steroids or NSAIDS in managing pain, pain resolution may be impaired by potent antiinflammatories, rendering them counterproductive to long-term outcomes.

This report was written up in the NY Times.