Perspectives in Pain Research 2014: Neuroinflammation and glial cell activation: The cause of transition from acute to chronic pain?
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Bibliographic record
Abstract
Background It is unknown why an acute pain condition under various circumstances can transition into a chronic pain condition. There has been a shift towards neuroinflammation and hence glial cell activations specifically in the dorsal root ganglion and spinal cord as a mechanism possibly driving the transition to chronic pain. This has led to a focus on non-neuronal cells in the peripheral and central nervous system. Besides infiltrating macrophages, Schwann cells and satellite glial cells release cytokines and therefore important mechanisms in the maintenance of pain. Activated Schwann cells, satellite glial cells, microglia, and astrocytes may contribute to pain sensitivity by releasing cytokines leading to altered neuronal function in the direction of sensitisation. Aims of this perspective paper 1) Highlight the complex but important recent achievement in the area of neuroinflammation and pain at spinal cord level and in the dorsal root ganglion. 2) Encourage further research which hopefully may provide better understanding of new key elements driving the transition from acute to chronic pain. Recent results in the area of neuroinflammation and pain Following a sciatic nerve injury, local macrophages, and Schwann cells trigger an immune response immediately followed by recruitment of blood-derived immune cells. Schwann cells, active resident, and infiltrating macrophages release proinflammatory cytokines. Proinflammatory cytokines contribute to axonal damage and also stimulate spontaneous nociceptor activity. This results in activation of satellite glial cells leading to an immune response in the dorsal root ganglia driven by macrophages, lymphocytes and satellite cells. The anterograde signalling progresses centrally to activate spinal microglia with possible up regulation of glial-derived proinflammatory/pronociceptive mediators. An important aspect is extrasegmental spreading sensitisation where bilateral elevations in TNF-α, IL-6, and IL-10 are found in dorsal root ganglion in neuropathic models. Similarly in inflammatory pain models, bilateral up regulation occurs for TNF-α, IL-1 β, and p38 MAPK. Bilateral alterations in cytokine levels in the DRG and spinal cord may underlie the spread of pain to the uninjured side. An important aspect is how the opioids may interact with immune cells as opioid receptors are expressed by peripheral immune cells and thus can induce immune signaling changes. Furthermore, opioids may stimulate microglia cells to produce proinflammatory cytokines such as IL-1. Conclusions The present perspective paper indicates that neuroinflammation and the associated release of pro-inflammatory cytokines in dorsal root ganglion and at the spinal cord contribute to the transition from acute to chronic pain. Neuroinflammatory changes have not only been identified in the spinal cord and brainstem, but more recently, in the sensory ganglia and in the nerves as well. The glial cell activation may be responsible for contralateral spreading and possible widespread sensitisation. Implications Communication between glia and neurons is proposed to be a critical component of neuroinflammatory changes that may lead to chronic pain. Sensory ganglia neurons are surrounded by satellite glial cells but how communication between the cells contributes to altered pain sensitivity is still unknown. Better understanding may lead to new possibilities for (1) preventing development of chronic pain and (2) better pain management.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.010 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it