Medical, neurobiological, and psychobehavioral perspectives of mastocytosis: a case report.

BACKGROUND: Cutaneous mastocytosis is a rare pathology characterized by an abnormal proliferation and degranulation of mast cells, affecting the skin. Here we present the case of a patient suffering from chronic resistant mastocytosis. An original integrative method of evaluation was tested in this patient, to improve therapeutic management. It integrated the interactions between stressful life events and medical history as well as psychobehavioral components and neurobiological factors. CASE PRESENTATION: The patient was a 65-year-old Caucasian woman. The cutaneous symptoms of mastocytosis had progressively evolved over the past 36 years, increasingly affecting the patient's quality of life. At the time of the evaluation, psoralen and ultraviolet A therapy had reduced pruritus, but very unsightly brown-red maculopapules persisted on the chest, back, and arms. We proposed an integrative diagnosis that combined a semistructured interview, a psychometric assessment with the Millon Behavioral Medicine Diagnostic tool, and the collection of medical data. The medical data were compared with the analysis of the significant events in the patient's life, to determine the threshold of tolerance to stress beyond which the skin symptoms led to profuse thrusts of pruritus. At the same time, the psychobehavioral profile of the patient was determined; this highlighted how social isolation, the denigrated coping style, and problematic compliance could influence the extension of dermatological symptoms. The effects of stressors on the infiltration and degranulation of skin mast cells have been discussed in light of the neurobiological processes currently known. At the end of the evaluation, a new therapeutic strategy was proposed. CONCLUSION: This case report reveals the mind-body relationship of a patient suffering from mastocytosis. It highlights the points of vulnerability and the adaptative strategies specific to each patient to be considered in therapeutic management of other resistant chronic diseases.

The effects of viscero-somatic interactions on thalamic mast cell recruitment in cystitic rats.

Mast cells accessing the brain parenchyma through the blood-brain barrier in healthy animals are limited to pre-cortical sensory relays - the olfactory bulb and the thalamus. We have demonstrated that unilateral repetitive stimulation of the abdominal wall generates asymmetry in midline thalamic mast cell (TMC) distribution in cyclophosphamide-injected rats, consisting of contralateral side-prevalence with respect to the abdominal wall stimulation. TMC asymmetry 1) was generated in strict relation with cystitis, and was absent in disease-free and mesna-treated animals, 2) was restricted to the anterior portion of the paraventricular pars anterior and reuniens nuclei subregion, i.e., the rostralmost part of the paraventricular thalamic nucleus, the only thalamic area associated with viscero-vagal and somatic inputs, via the nucleus of the solitary tract, and via the medial contingent of the spinothalamic tract, respectively, and 3) originated from somatic tissues, i.e., the abdominal wall where bladder inflammation generates secondary somatic hyperesthesia leading to referred pain in humans. Present data suggest that TMCs may be involved in thalamic sensory processes, including some aspects of visceral pain and abnormal visceral/somatic interactions.

Differential effects of two analgesic drugs, morphine chlorhydrate and acetylsalicylic acid, on thalamic mast cell numbers in rat.

Thalamic mast cells (TMCs), the only immunocytes known to infiltrate the brain in physiological conditions, respond to pharmacological agents including sumatriptan - a serotonergic anti-migraine agent - that increases their number. We analysed the effects of two other main analgesics: morphine chlorhydrate, a micro opioid agonist, and acetylsalicylic acid (ASA), a non-steroidal anti-inflammatory drug. All three drugs have specific modes of action, and morphine and ASA, unlike sumatriptan, are also known to interact with peripheral mast cells. Only ASA was effective in promoting TMC number decrease. TMCs, unlike other mast cells, do not express cyclooxygenase (COX) - the key enzyme in the production of prostanoids and the main site of action of ASA - thus dismissing a direct local cellular COX-mediated action. Direct TMC COX-independent mechanisms or effects mediated via distant populations of COX-positive cells such as platelets, leptomeningeal, endothelial and peripheral mast cells are thus probable. ASA, morphine and sumatriptan have distinct TMC effects, suggesting that the TMC number variations they induce are more likely to derive from systemic vasoactive actions than from pharmacological mechanisms devoted to pain relief.

Evidence for serotonin influencing the thalamic infiltration of mast cells in rat.

Serotonin (5-HT) is involved in neuroimmunomodulation. We analyzed the effects of sumatriptan, a 5-HT(1B/1D) receptor agonist, and ondansetron, a 5-HT(3) receptor antagonist, on thalamic mast cell (TMC) population, the only immunocytes known to infiltrate the brain in physiological conditions. Only sumatriptan was effective, significantly increasing TMC numbers versus controls, and especially those containing 5-HT. 5-HT(1B) receptors are concentrated in the median eminence on non-serotonergic axonal endings, probably hypothalamic terminal fibers, involved in hypothalamic-pituitary neuroendocrine modulating processes. TMC variations could reflect serotonergic actions on these fibers. TMCs would thus be cellular interfaces mediating immune action in the nervous system in relation with the hormonal status of the organism.

A one-step dual-labeling method for antigen detection in mast cells.

This paper describes a one-step light microscopy method for demonstrating the antigen contents of unequivocally identified mast cells. It is based on the differential metachromatic properties of proteoglycans, mostly heparin and chondroitin sulfate, and 1-naphthol in the presence of toluidine blue in an acidic medium. Proteoglycans occur in all mast cells and 1-naphthol is used to demonstrate the peroxidase activity of the sections treated by the horseradish peroxidase-labeled avidin-biotin complex method for antigen detection. Granules containing proteoglycans present the classical metachromatic reaction by appearing purplish-red, while granules containing antigen appear a brilliant green. When both types of granules are distinct inside the cell, single- and double-stained cells can be accurately separated and counted. We hope that this new procedure will contribute to a further identification of mast cell mediator contents and to a better understanding of the physiology of this cellular population.

Increase of rat medial habenular mast cell numbers by systemic administration of cyclophosphamide.

Cyclophosphamide administration generates systemic toxicity having immune and nervous consequences. After focusing on nervous consequences by studying neuronal activity, we now consider cyclophosphamide impact on diencephalic mast cells as part of the brain immune system. Diencephalon, the ultimate sensory relay before neocortical processing, is the only brain structure containing mast cells. Single cyclophosphamide administration (100 mg/(kg 1 ml ip)) was performed in naturally behaving rats and diencephalic mast cell numbers were analyzed once all drug effects had developed (4 h postinjection). Significant increases were observed only in the medial habenular nucleus--bilaterally and especially in its caudal portion. Mast cell increase is temporally related to behavioral impairment and evoked neuronal activity in a restricted number of visceral/limbic extrathalamic structures. The medial habenular nucleus belongs to the limbic system involved in processing emotional reactions and regulation of the autonomic nervous system. Its involvement during toxic challenge is highly compatible with its presumed function in the maintenance of vital functions.

Exploration, anxiety, and spatial memory in transgenic anophthalmic mice.

Contradictory results are found in the literature concerning the role of vision in the perception of space or in spatial navigation, in part because of the lack of murine models of total blindness used so far. The authors evaluated the spatial abilities of anophthalmic transgenic mice. These mice did not differ qualitatively from their wild-type littermates in general locomotor activity, spontaneous alternation, object exploration, or anxiety, but their level of exploratory activity was generally lower. In the spatial version of the water maze, they displayed persistent thigmotaxic behavior and showed severe spatial learning impairments. However, their performances improved with training, suggesting that they may have acquired a rough representation of the platform position. These results suggest that modalities other than vision enable some degree of spatial processing in proximal and structured spaces but that vision is critical for accurate spatial navigation.

Neural and angiogenic defects in eyes of transgenic mice expressing a dominant-negative FGF receptor in the pigmented cells.

Fibroblast growth factors (FGF) are multipotent cytokines with demonstrated mitogenic, neurotrophic and angiogenic properties. There is evidence that they have multiple functions during and after development of the vertebrate eye. Amongst these, the role of FGF receptor mediated signaling in the retinal pigmented epithelium (RPE) is not yet well understood. FGF-2 is produced in RPE cells and may play a role in photoreceptor development and/or survival in vivo. It may also stimulate growth of melanocytes and angiogenesis in the choroid. To address these questions, we have specifically disrupted FGF signaling by generating lines of transgenic mice expressing dominant-negative FGF receptor 1 (FGFR-1) in the pigmented cells. Histological analysis of the eyes were conducted on hemizygous and homozygous mice at different ages. In homozygotes, eye growth is strongly impaired during embryogenesis leading to massive eye degeneration seen in the early post-natal stages. In hemizygotes, the choroid is thinned and the finger-like junctions between RPE cells and photoreceptors are disrupted. Scanning electron microscopy of the choroid vasculature showed that choriocapillary density, diameter and branching are strongly affected. As mice age, they develop progressive retinal degeneration as evidenced by photoreceptor cell loss. Our results are in agreement with the hypothesis that FGF signaling in the RPE participates in photoreceptor survival in vivo. Our model provides evidence that FGF signaling is also involved in choroidal angiogenesis by a process that could relate to induction of terminal branching.

Entrainment of the medullary respiratory generators by electrical stimulation in the cervical grey matter on in vitro preparations of newborn rat.

The present study describes how the medullary respiratory generators (mRGs) can be driven by periodic electrical stimulations applied to the ventral part of the spinal grey matter at the C5 level. The general effect of an electrical stimulus (5 pulses at 200 Hz and between 50 and 80 microA) was either to delay or to advance the occurrence of the medullary respiratory burst via a resetting process, depending on its time of application within the corresponding cycle. Compared to the spontaneous medullary periods, the phase-response curves show that the non-spontaneous medullary period increased progressively when the electrical stimulus was applied within the first two-thirds of the corresponding medullary cycle and decreased when it was applied within the last third of the latter one. These curves were constructed in order to predict the limits of a stable 1:1 entrainment. As predicted, the 1:1 entrainment was obtained when we stimulated repetitively at resetting intensity within the frequency limits determined by the phase-response curves. The entrainment became harmonic (2:1, 3:1, 4:1) when the stimulation frequency increased near submultiples of the fundamental mRGs frequency. From these data, we conclude on the presence of ascending connections from the C5 segment of the spinal cord which might be involved in the realisation of the locomotor-respiratory coupling.

Effects of CO2 and pH on the spinal respiratory rhythm generator in vitro.

In vitro brainstem spinal cord preparations isolated from newborn rats were used to separately test the effects of modifications of FCO2 and pH of artificial cerebrospinal fluid on the frequency and amplitude of spinal respiratory activity recorded from C2-C8 ventral roots. Different substances such as L-glutamic acid (3 x 10[-3] M), N-methyl-D-aspartic acid (5 x 5 x 10[-6] M), amphetamine (6 mg/100 ml), 5-hydroxytryptophane (10[-3] M), or modified K+ (10[-3] M) were tested for their capacity to elicit stable changes in spinal respiratory activity over a long time period (more than 30 min) and with high frequency of occurrence, i.e., in at least 50% of the cases. None of the above drugs were found to be suitable for the investigation of the chemosensitivity of the spinal respiratory generator (sRG) because they were only able to maintain spinal respiratory activity for around 15 min. Given these data, the previously used procedure of activation through initial deep diethyl ether anaesthesia of newborn rats was employed [3] to test the chemosensitivity of the sRG because this treatment resulted in the maintenance of spinal respiratory activity with a regular pattern for 30 min, even if it occurred in only 25% of the preparations. After an increase in FCO2 from 5 to 7% (at constant pH 7.4), a significant (p < 0.05) enhancement of the mean frequency was observed on spinal respiratory bursting in both brainstem spinal cord and isolated spinal cord preparations. The changes in burst amplitude, however, were quite variable from one experiment to the other. At constant FCO2 (5%), a decrease in pH from 7.4 to 7.2 enhanced spinal respiratory frequency on brainstem spinal cord or isolated spinal cord preparations, while an increase in pH from 7.4 to 7.6 decreased it. Under these pH conditions, we did not observe any reproducible variations in spinal burst amplitude. From these results, we conclude that this spinal generator is chemosensitive to both CO2 and [H+], suggesting that it belongs to the respiratory system. Our data provide evidence for the existence of spinal CO2 and/or H+ chemoreceptors.

Localization of the spinal respiratory rhythm generator by an in vitro electrophysiological approach.

An in vitro electrophysiological approach allowed the localization of the spinal respiratory generator (sRG) within the cervical cord of newborn rats. Rostral and caudal limits were determined through transections of the successive spinal segments. The sRG is mainly located in the C5 segment with a partial extension in the C4 and C6 segments. The presence of two lateralized sRG was found after a split of the brain stem cervical cord from T8 to C1. Spinal respiratory activity could be kept synchronous after this split in the right and left halves of the spinal cord. This spinal activity also displayed a bilateral synchrony on separated spinal cord preparations after a C1 transection with no split. These findings are the first attempt to localize the sRG and are discussed in terms of bilateral segmental coupling and of interactions between the medullary and the spinal respiratory generators.

Interactions between medullary and spinal respiratory rhythm generators in the in vitro brainstem spinal cord preparation from newborn rats.

As medullary and spinal respiratory activities coexist in the in vitro brainstem spinal cord preparation from newborn rats previously deeply anaesthetized with diethyl ether, we sought evidence for reciprocal interactions between the medullary and spinal respiratory generators. A descending influence of medullary onto spinal respiratory generators has been characterized by the constant onset latency of the spinal burst within the corresponding medullary respiratory cycle. Non-harmonic (29%) and harmonic (9%) correlations were observed between the two phenomena, but correlations could also be low (27%) or absent (35%). Variations in the pH or FCO2 of the artificial cerebrospinal fluid were able to induce or suppress this medullary control of spinal respiratory activity. An ascending relationship between spinal and medullary respiratory generators has been revealed as a systematic variation of the medullary period due to resetting. Depending on the timing of the spinal respiratory activity, the medullary burst could be either advanced through a shortened medullary period, or delayed through a lengthened one. In conclusion, it was possible to show the existence of reciprocal relationships between the medullary and spinal respiratory generators in the in vitro brainstem spinal cord preparation from newborn rats. These results are interpreted in relation to the central interactions between locomotion and respiration in mammals which occur during rapid propulsion and which could be mediated by the spinal respiratory generator.

[Possible existence of spinal inspiratory activity in the in vitro brain stem-spinal cord preparation from newborn rats]. / Existence possible d'une activité inspiratoire spinale sur préparation in vitro tronc cérébral-moelle de rat nouveau-né.

Summing up with classical shortlasting inspirations, periodic longlasting inspirations (approximately 10 s) may be recorded with the normal inspirations through plethysmographic method in the intact newborn rat under deep diethyl ether anaesthesia. When they are present in vivo, the fast brainstem-spinal cord isolation allows to record in vitro periodic longlasting motor bursts (10-25 s) on C2-C8 ventral roots adding to shortlasting respiratory bursts (1-3 s) on C1-T13 ventral roots. Both kinds of rhythmic activities display a synchronous bilateral pattern. The longlasting bursts are maintained after a C2 spinal transection, especially if they have been induced by phenylephrine hydrochloride superfusion (0.4-0.5 mM).