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1 Peripheral in¯ammation is characterized by heightened pain sensitivity. This hyperalgesia is the consequence of the release of in¯ammatory mediators, cytokines and growth factors. A key participant is the induction of the neurotrophin nerve growth factor (NGF) by interleukin-1b (IL-1b). 2 Tumour necrosis factor a (TNFa) has been shown both to produce hyperalgesia and to upregulate IL-1b. We have now examined whether the induction of TNFa in in¯ammatory lesions contributes to in¯ammatory sensory hypersensitivity by inducing IL-1b and NGF. 3 The intraplantar injection of complete Freund's adjuvant (CFA) in adult rats produced a localized in¯ammation of the hindpaw with a rapid (3 h) reduction in withdrawal time in the hot plate test and in the mechanical threshold for eliciting the¯exion withdrawal re¯ex. 4 The CFA-induced in¯ammation resulted in signi®cant elevation in the levels of TNFa, IL-1b and NGF in the in¯amed paw. In the case of TNFa, an elevation was detected at 3 h, rose substantially at 6 h, peaked at 24 h and remained elevated at 5 days, with similar but smaller changes in the contralateral non-in¯amed hindpaw. No increase in serum TNFa was detected at 24 h post CFA injection. 5 Intraplantar recombinant murine TNFa injections produce a short-lived (3 ± 6 h) dose-dependent (50 ± 500 ng) increase in thermal and mechanical sensitivity which was signi®cantly attenuated by prior administration of anti-NGF antiserum. 6 Intraplantar TNFa (100 ± 500 ng) also elevated at 6 but not 48 h the levels of IL-1b and NGF in the hindpaw. 7 A single injection of anti-TNFa antiserum, 1 h before the CFA, at a dose sucient to reduce the eects of a 100 ng intraplantar injection of TNFa, signi®cantly delayed the onset of the resultant in¯ammatory hyperalgesia and reduced IL-1b but not NGF levels measured at 24 h. 8 The elevation of TNFa in in¯ammation, by virtue of its capacity to induce IL-1b and NGF, may contribute to the initiation of in¯ammatory hyperalgesia.

Peripheral inflammation is associated with the local production of neuroactive inflammatory cytokines and growth factors. These may contribute to inflammatory pain and hyperalgesia by directly or indirectly altering the function or chemical phenotype of responsive primary sensory neurones. To investigate this, inflammation was produced by the intraplantar injection of complete Freund's adjuvant (CFA) in adult rats. This resulted in a significant elevation in interleukin‐ip (IL‐1β) and nerve growth factor (NGF) levels in the inflamed tissue and of the peptides, substance P and calcitonin gene‐related peptide (CGRP) in the L4 dorsal root ganglion 48 h post CFA injection. The effects of a steroidal (dexamethasone) and a non‐steroidal (indomethacin) anti‐inflammatory drug on the levels of NGF and IL‐1β in inflamed tissue were investigated and compared with alterations in behavioural hyperalgesia and neuropeptide expression in sensory neurones. Systemic dexamethasone (120 μg kg−1 per day starting the day before the CFA injection) had no effect on the inflammatory hyperalgesia. When the dose was administered 3 times daily, a reduction in mechanical and to a lesser extent thermal sensitivity occurred. Indomethacin at 2 mg kg−1 daily (i.p.) had no effect on the hyperalgesia and a dose of 4 mg kg−1 daily was required to reduce significantly mechanical and thermal hypersensitivity. The increase in NGF produced by the CFA inflammation was prevented by both dexamethasone and indomethacin, but only at the higher dose levels. Dexamethasone at the lower and higher dose regimes diminished the upregulation of IL‐1β whereas indomethacin had an effect only at the higher dose. The increase in SP and CGRP levels produced by the CFA inflammation was prevented by dexamethasone and indomethacin at the lower and higher dose regimes. Intraplantar injections of IL‐1β (0.01, 0.1 and 1 ng) produced a brief (6 h) thermal hyperalgesia and an elevation in cutaneous NGF levels which was prevented by pretreatment with human recombinant IL‐1 receptor antagonist (IL‐1 ra) (0.625 μg, i.v.). The thermal hyperalgesia but not the NGF elevation produced by intraplantar IL‐1β (1 ng) was prevented by administration of a polyclonal neutralizing anti‐NGF serum. IL‐1 ra significantly reduced the mechanical hyperalgesia produced by CFA for 6 h after administration as well as the CFA‐induced elevation in NGF levels. Anti‐NGF pretreatment substantially reduced CFA‐induced mechanical and thermal hyperalgesia without reducing the elevation in IL‐1β. Intraplantar NGF (0.O2, 0.2 and 2 μg) injections produced a short lasting thermal and mechanical hyperalgesia but did not change IL‐1β levels in the hindpaw skin. Our results demonstrate that IL‐1β contributes to the upregulation of NGF during inflammation and that NGF has a major role in the production of inflammatory pain hypersensitivity.

BackgroundDespite decades of intensive research, to date, there is no accepted diagnosis for Parkinson’s disease (PD) based on biochemical analysis of blood or CSF. However, neurodegeneration in the brains of PD patients begins several years before the manifestation of the clinical symptoms, pointing to serious flaw/limitations in this approach.ResultsTo explore the potential use of alpha-synuclein (α-syn) species as candidate biomarkers for PD, we generated specific antibodies directed against wide array of α-syn species, namely total-, oligomeric- and phosphorylated-Ser129-α-syn (t-, o- and p-S129-α-syn). Next we sought to employ our antibodies to develop highly specific ELISA assays to quantify α-syn species in biological samples. Finally we verified the usefulness of our assays in CSF samples from 46 PD patients and 48 age-matched healthy controls. We also assessed the discriminating power of combining multiple CSF α-syn species with classical Alzheimer’s disease biomarkers. The combination of CSF o-/t-α-syn, p-S129-α-syn and p-tau provided the best fitting predictive model for discriminating PD patients from controls. Moreover, CSF o-α-syn levels correlated significantly with the severity of PD motor symptoms (r = -0.37).ConclusionOur new ELISA assays can serve as research tools to address the unmet need for reliable CSF biomarkers for PD and related disorders.Electronic supplementary materialThe online version of this article (doi:10.1186/s13024-016-0072-9) contains supplementary material, which is available to authorized users.

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