Neuro-immune crosstalk and food allergy: Focus on enteric neurons and mucosal mast cells

The nervous system and the immune system individually play important roles in regulating the processes necessary to maintain physiological homeostasis, respond to acute stress and protect against external threats. These two regulating systems for maintaining the living body had often been assumed to function independently. Allergies develop as a result of an overreaction of the immune system to substances that are relatively harmless to the body, such as food, pollen and dust mites. Therefore, it has been generally supposed that the development and pathogenesis of allergies can be explained through an immunological interpretation. Recently, however, neuro-immune crosstalk has attracted increasing attention. Consequently, it is becoming clear that there is close morphological proximity and physiological and pathophysiological interactions between neurons and immune cells in various peripheral tissues. Thus, researchers are now beginning to appreciate that neuro-immune interactions may play a role in tissue homeostasis and the pathophysiology of immune-mediated disease, but very little information is available on the molecular basis of these interactions. Mast cells are a part of the innate immune system implicated in allergic reactions and the regulation of host–pathogen interactions. Mast cells are ubiquitous in the body, and these cells are often found in close proximity to nerve fibers in various tissues, including the lamina propria of the intestine. Mast cells and neurons are thought to communicate bidirectionally to modulate neurophysiological effects and mast cell functions, which suggests that neuro-immune interactions may be involved in the pathology of allergic diseases.     

Neuroimaging the pain network – Implications for treatment

In this chapter, we provide an overview of neuroimaging studies in chronic pain. We start with an introduction about the phenomenology of pain. In the following section, the application of functional and structural imaging techniques is shown in selected chronic pain syndromes (chronic back pain, fibromyalgia syndrome (FMS), phantom limb pain, and complex regional pain syndrome (CRPS)), and commonalities and peculiarities of imaging correlates across different types of chronic pain are discussed. We conclude this chapter with implications for treatments, with focus on behavioral interventions, sensory and motor trainings, and mirror and motor imagery trainings.     

Long-term effects of concussion on relevancy-based modulation of somatosensory-evoked potentials

ObjectiveThe purpose of this investigation was to better understand the effects of concussions on the ability to selectively up or down-regulate incoming somatosensory information based on relevance.MethodsMedian nerve somatosensory-evoked potentials (SEPs) were elicited from electrical stimulation and recorded from scalp electrodes while participants completed tasks that altered the relevance of specific somatosensory information being conveyed along the stimulated nerve.ResultsWithin the control group, SEP amplitudes for task-relevant somatosensory information were significantly greater than for non-relevant somatosensory information at the earliest cortical processing potentials (N20-P27). Alternatively, the concussion history group showed similar SEP amplitudes for all conditions at early processing potentials, however a pattern similar to controls emerged later in the processing stream (P100) where both movement-related gating and facilitation of task-relevant information were present.ConclusionsPreviously concussed participants demonstrated impairments in the ability to up-regulate relevant somatosensory information at early processing stages. These effects appear to be chronic, as this pattern was observed on average several years after participants’ most recent concussion.SignificanceGiven the role of the prefrontal cortex in relevancy-based facilitation during movement-related gating, these findings lend support to the notion that this brain area may be particularly vulnerable to concussive forces.     

A modality-specific somatosensory evoked potential test protocol for clinical evaluation: A feasibility study

ObjectiveWe aimed to establish an objective neurophysiological test protocol that can be used to assess the somatosensory nervous system.MethodsIn order to assess most fiber subtypes of the somatosensory nervous system, repetitive stimuli of seven different modalities (touch, vibration, pinprick, cold, contact heat, laser, and warmth) were synchronized with the electroencephalogram (EEG) and applied on the cheek and dorsum of the hand and dorsum of the foot in 21 healthy subjects and three polyneuropathy (PNP) patients. Latencies and amplitudes of the modalities were assessed and compared. Patients received quantitative sensory testing (QST) as reference.ResultsWe found reproducible evoked potentials recordings for touch, vibration, pinprick, contact-heat, and laser stimuli. The recording of warm-evoked potentials was challenging in young healthy subjects and not applicable in patients. Latencies were shortest within Aβ-fiber-mediated signals and longest within C-fibers. The test protocol detected function loss within the Aβ-fiber and Aδ-fiber-range in PNP patients. This function loss corresponded with QST findings.ConclusionIn this pilot study, we developed a neurophysiological test protocol that can specifically assess most of the somatosensory modalities. Despite technical challenges, initial patient data appear promising regarding a possible future clinical application.SignificanceEstablished and custom-made stimulators were combined to assess different fiber subtypes of the somatosensory nervous system using modality-specific evoked potentials.     

Defining sensory modulation: A review of the concept and a contemporary definition for application by occupational therapists

Background: Sensory interventions are prevalent amongst adult mental health practitioners and are supported by major stakeholders and policy makers across the world. The term commonly used by occupational therapists applying sensory practices is sensory modulation, however this term has evolved.

Aims: This paper aims to investigate and clarify the definition of ‘sensory modulation’ for application by occupational therapists.

Method: A framework guided this concept analysis on sensory modulation. A summative content analysis approach was employed to code results.

Results: Six conceptual themes for sensory modulation were identified. 81% of authors defined sensory modulation as consisting of more than one of these themes. 18% of authors defined sensory modulation as both a neurophysiological process and means to regulate behaviour.

Conclusion: The concept of sensory modulation has evolved in occupational therapy practice. The authors summarise with the following proposed definition of sensory modulation for contemporary occupational therapy practice: ‘Sensory modulation is considered a twofold process. It originates in the central nervous system as the neurological ability to regulate and process sensory stimuli; this subsequently offers the individual an opportunity to respond behaviourally to the stimulus’.

Significance: A contemporary definition of ‘sensory modulation’ has been identified for occupational therapy practice.     

La maladie de l’oreille du surfeur : l’imaginaire du soi naturalisé à partir d’une pathologie due à l’immersion en milieu aquatique

GoalsStarting from the example of the exostosis of the external auditory canal, a modification due to the impact of the sea on the body, this article considers how this pathology is experienced and interpreted by those who contract it. After defining “surfer's ear” from an anthropo-medical point of view, we will address the meaning that individuals give to it, such as the belief of becoming fish.MethodologyOver the course of several years of field observation and interviews, mainly on the beaches of the Atlantic Pyrenees, we were able to compare different individuals’ discourses about how the surfing body, immersed in nature, is perceived and experienced.ResultsThis helps to understand thoughts that can link people to the ocean, and more widely to nature, in our contemporary Western society. Thus, penetrating and being penetrated by this living water implies a sensual relationship with the environment, in a search both for erotic pleasure and an enveloping maternal security, lost from birth.DiscussionThis relationship to the environment implements a sensory ecology where the human becomes nature, and nature takes human form. This is an occasion for the reinvention of links, not in an opposition between human and non-human, but by reminding humans that they can find balance in abandoning themselves to nature.ConclusionPathologies of the ear define an imaginary clinic of the body. The body is thus rendered unfit by the physical sensations of marine pathology but, above all, by the belief in a psychic envelopment in water.     

Seven cervical sensorimotor control tests measure different skills in individuals with chronic idiopathic neck pain

BackgroundSensorimotor control is commonly reported in neck pain research and rapidly gaining interest in clinical practice. Joint position error (conventional and torsion), postural balance, subjective visual vertical, head tilt response, The Fly®, smooth pursuit neck torsion and head steadiness are tests that have been reported to assess cervical sensorimotor control. However, it is unknown whether clinicians could use one test, or a test battery, to appropriately assess cervical sensorimotor control and improve efficiency. Our main research question is: Do seven cervical sensorimotor control tests measure unique or similar characteristics of sensorimotor control in individuals with chronic idiopathic neck pain?MethodsPrinciple components factor analysis. Data from seven cervical sensorimotor control tests of 50 participants with chronic idiopathic neck pain were included. Individual factors, potentially related to sensorimotor control, were determined by Eigen values >1.00 and inspection of a loading plot. Items with loadings ≥0.40 were considered satisfactory for inclusion in a factor.ResultsAll cervical sensorimotor control tests were found to measure unique skills. Four factors were isolated with two, postural balance and head steadiness, accounting for most of the variance across tests. The remaining two factors, continuous movement accuracy and perceived verticality, contributed less to the observed variance.ConclusionPostural balance and head steadiness were the major underlying factors explaining cervical sensorimotor control in the current sample. However, our results imply that all seven tests are independent and measure different skills. It is not possible to recommend a test battery for clinical practice, as all tests measure unique skills which appear to be independent of each other.     

Spinal interleukin-6 contributes to central sensitisation and persistent pain hypersensitivity in a model of juvenile idiopathic arthritis

Pain is the most debilitating symptom in juvenile idiopathic arthritis. As pain correlates poorly to the extent of joint pathology, therapies that control joint inflammation are often inadequate as analgesics. We test the hypothesis that juvenile joint inflammation leads to sensitisation of nociceptive circuits in the central nervous system, which is maintained by cytokine expression in the spinal cord. Here, transient joint inflammation was induced in postnatal day (P)21 and P40 male Sprague-Dawley rats with a single intra-articular ankle injection of complete Freund’s adjuvant. Hindpaw mechanical pain sensitivity was assessed using von Frey hair and weight bearing tests. Spinal neuron activity was measured using in vivo extracellular recording and immunohistochemistry. Joint and spinal dorsal horn TNFα, IL1β and IL6 protein expression was quantified using western blotting. We observed greater mechanical hyperalgesia following joint inflammation in P21 compared to P40 rats, despite comparable duration of swelling and joint inflammatory cytokine levels. This is mirrored by spinal neuron hypersensitivity, which also outlasted the duration of active joint inflammation. The cytokine profile in the spinal cord differed at the two ages: prolonged upregulation of spinal IL6 was observed in P21, but not P40 rats. Finally, spinal application of anti-IL-6 antibody (30 ng) reduced the mechanical hyperalgesia and neuronal activation. Our results indicate that persistent upregulation of pro-inflammatory cytokines in the spinal dorsal horn is associated with neuronal sensitisation and mechanical hyperalgesia in juvenile rats, beyond the progress of joint pathology. In addition, we provide proof of concept that spinal IL6 is a key target for treating persistent pain in JIA.