{'fraction_non_alphanumeric': 0.01911764705882353, 'fraction_numerical': 0.004779411764705883, 'mean_word_length': 5.432624113475177, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Lack of Translatable Proinflammatory Cytokines in Cerebrospinal Fluid in Rats With Increased Hyperalgesia With or Without Fentanyl Treatment.

Letters to the Editor LETTERS TO THE EDITOR translatability in CSF (IL-β and TNFα) although so prominent and long lasting in spinal cord/DRG is the topic of this communication. Although it was suggested that the observed increase in proinflammatory cytokines in contralateral DRG was attributable to transfer via cellular junction or unclear pathway,1 still lack of diffusion (albeit passive one) of IL-β, IL-6, and/or TNFα into CSF may have implications worthy of discussion. First, lack of CSF translatability of increased levels of the examined cytokines1 suggested that there was no transfer that occurred between DRG and CSF despite higher production of the cytokines in the 3 treatments used in the study. Even simple diffusion mechanism should have rendered translatability of the findings in the CSF. Therefore, is this suggestive of an efflux component being developed immediately post active treatments, which effectively removed the proinflammatory cytokines? Second, lack of translatability in CSF of these biomarkers may represent a bigger concern from diagnostic and prognostic perspectives. Because CSF is an important conduit that can serve to evaluate any pathophysiological distress of the brain regions due to inflammation, trauma, neurodegeneration, etc, lack of translatability will provide a different picture and interpretation if one examines CSF in isolation. In this context, Yeager et al2 demonstrated the occurrence of elevated cytokine IL-6 levels in the CSF in patients undergoing major orthopedic surgery. The data also confirmed that due to lack of correlation with circulatory plasma cytokine (IL-6), there was a central mechanism responsible for IL-6 production in the CSF.2 Therefore, importance of CSF tapping in patients was highlighted to understand pathophysiological status of the central mechanisms involved in surgery which otherwise would have been missed if systemic circulatory cytokines were used as a biomarker. On the other hand, Coughlin et al3 showed the importance of systemic inflammatory cytokine (IL-6) levels in the early onset schizophrenic patients. In this study, the CSF IL-6 levels were highly correlated with those in plasma suggesting the importance of monitoring plasma samples of patients. In summary, although the mechanism(s) relating to absence of translatability of elevated procytokines in CSF or presence of such biomarkers in the contralateral DGR is not understood,1 the reported findings should lead to delineation of future experiments that may throw more light to understand this intriguing phenomenon.