Traumatic peripheral neuropathic pain is a complex syndrome caused by a primary lesion or dysfunction of the peripheral nervous system. Secondary to the lesion, resident or infiltrating macrophages proliferate and initiate a cross-talk with the sensory neurons, at the level of peripheral nerves and sensory ganglia. The neuron–macrophage interaction, which starts very early after the lesion, is very important for promoting pain development and for initiating changes that will facilitate the chronicization of pain, but it also has the potential to facilitate the resolution of injury-induced changes and, consequently, promote the reduction of pain. This review is an overview of the unique characteristics of nerve-associated macrophages in the peripheral nerves and sensory ganglia and of the molecules and signaling pathways involved in the neuro-immune cross-talk after a traumatic lesion, with the final aim of better understanding how the balance between pro- and anti-nociceptive dialogue between neurons and macrophages may be modulated for new therapeutic approaches.
Applied research programs in the remediation of contaminated areas can be used also for gaining insights in the physiological and ecological mechanisms supporting the resistance of plant communities in stress conditions due to toxic elements. The research hypothesis of this study was that in the heavily contaminated but nutrient-poor substrate of mine tailing dams, the beneficial effect of inoculation with arbuscular mychorrizal fungi (AMF) is due to an improvement of phosphorus nutrition rather than to a reduction of toxic element transfer to plants. A concept model assuming a causal chain from root colonization to element uptake, oxidative stress variables, and overall plant development was used. The methodological novelty lies in coupling in a single research program experiments conducted at three scales: pot, lysimeter, and field plot, with different ages of plants at the sampling moment (six subsets of samples in all). The inoculation with AMF in expanded clay carrier had a beneficial effect on the development of plants in the amended tailing substrate heavily contaminated with toxic elements. The effect of inoculation was stronger when the quantity of expanded carrier was smaller (1 % vs. 7 % inoculum), probably because of changes in substrate features. The improvement of plant growth was due mainly to an improvement in phosphorus nutrition leading to an increase of protein concentration and decrease of oxidative stress enzyme activity (superoxide dismutase and peroxidase). In a single data subset, an effect of inoculation on the uptake of several toxic elements could be proved (decrease of As concentration in plant roots correlated with a decrease of oxidative stress independent from the effect of P concentration increase). The multi-scale approach allowed us to find differences between the patterns characterising the data subsets. These subset-specific patterns point out the existence of physiological differences between plants in different development states (as a result of sampling at different plant ages). From an applied perspective, conclusions are drawn with respect to the use of plants in the monitoring programs of contaminated areas and the use of inoculation with AMF in the remediation of tailing dams.
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