Involvement of sensory nerve endings in cold and heat urticaria

Cold urticaria - What we know and what we do not know

Cold urticaria (ColdU) is a common form of chronic inducible urticaria characterized by the development of wheals, angioedema or both in response to cold exposure. Recent research and guideline updates have advanced our understanding and management of ColdU. Today, its pathophysiology is thought to involve the cold-induced formation of autoallergens and IgE to these autoallergens, which provoke a release of proinflammatory mediators from skin mast cells. The classification of ColdU includes typical and atypical subtypes. We know that cold-induced wheals usually develop on rewarming and resolve within an hour and that anaphylaxis can occur. The diagnosis relies on the patient's history and cold stimulation testing. Additional diagnostic work-up, including a search for underlying infections, should only be done if indicated by the patient's history. The management of ColdU includes cold avoidance, the regular use of nonsedating antihistamines and the off-label use of omalizumab. However, many questions regarding ColdU remain unanswered. Here, we review what is known about ColdU, and we present important unanswered questions on the epidemiology, underlying pathomechanisms, clinical heterogeneity and treatment outcomes. Our aim is to guide future efforts that will close these knowledge gaps and advance the management of ColdU.

Cold-Induced Skin Disorders

Background:

Humans are commonly exposed to extremes in temperature. Fortunately, our skin behaves as an anatomic and physiologic barrier during these periods. Exposure to cold temperatures may result in a variety of symptoms and disorders.

Objective:

Our current understanding of the pathophysiology, clinical presentation, and therapies of cold-induced skin disorders are reviewed.

Methods:

Studies, reviews, and book chapters that contained information on cold-induced skin disorders were reviewed.

Conclusion:

Cold-induced skin disorders are a heterogeneous group of disorders that cause great morbidity, particularly in cold climates. These entities can be classified as physiologic or pathologic responses to freezing or nonfreezing cold exposure.

Heat urticaria: a revision of published cases with an update on classification and management

Heat urticaria (HU) is a rare type of physical inducible urticaria, characterized by itchy erythema and well-demarcated weals appearing soon after heat exposure. Most cases occur in female patients aged 20-45 years. Both localized and generalized forms exist, depending on the limitation of the reaction to the skin area directly exposed to the physical stimulus or the involvement of distant sites, respectively. In most cases, HU is an immediate reaction, but delayed forms (mostly familial) have been described. HU is a long-lasting disease with overall duration at diagnosis of approximately 2 years. In about half of cases it is associated with systemic symptoms such as weakness, wheezing, headache, flushing, nausea, vomiting, diarrhoea, tachycardia, even dyspnoea or syncope. The main differential diagnosis includes cholinergic urticaria, exercise-induced anaphylaxis and solar urticaria. The diagnosis of HU is established by provocation testing, which is also helpful to evaluate the critical temperature threshold. The mean threshold temperature is about 44 °C. A heat desensitization programme can be an effective treatment. Nonsedating H1 antihistamines administered at licensed doses are the mainstay of symptomatic therapy in nearly 60% of patients, but full symptom relief is achieved in only a minority of them. Omalizumab has proven effective in recent case reports.

Modern approaches to the diagnosis and treatment of cold contact urticaria

Cold contact urticaria (CCU) is a common subtype of physical urticaria characterized by itchy wheals and/or angioedema due to skin mast cell activation and the release of proinflammatory mediators after cold exposure. The underlying causes are largely unknown. When CCU is suspected, cold stimulation tests and threshold testing should be done to confirm the diagnosis and to determine the severity and course of CCU, respectively. Avoidance of critical cold exposure should be recommended but is often impossible, especially for severely affected patients with high temperature and low exposure time thresholds. Symptomatic treatment of choice is the use of modern, nonsedating antihistamines. Patients should be informed that complete protection from CCU symptom development may require increased doses of antihistamines. Standardizing cold provocation tests and further characterization of the natural course of CCU and its variants may lead to a better understanding of the disease-driving mechanisms.

Localized cold urticaria to the face in a pediatric patient: a case report and literature review

We present a curious case of localized cold urticaria restricted to the face in a 10-year-old girl. Testing for the condition using an ice cube was positive only in the facial area. After 2 years, the patient continues to experience localized urticaria only on her face on cold exposure. A review of the available published medical literature on cold urticaria was performed using Ovid and PubMed databases. The literature search was not limited to the English language. Only three other cases of cold urticaria localized to the face were identified. Upon review of the published reports on cold urticaria and discussion of classification and diagnostic testing, we conclude that cold urticaria clearly is a rare and poorly understood entity.

Acquired cold urticaria: clinical picture and update on diagnosis and treatment

Acquired cold urticaria (ACU) is a frequent subtype of physical urticaria that is caused by the release of proinflammatory mast cell mediators after cold exposure. Although the underlying causes of ACU still remain to be clarified in detail, a wide range of diseases has been reported to be associated with ACU. This review gives an overview of the clinical picture, the differential diagnoses, diagnostic tests and the aetiology of ACU, and summarizes current and novel therapeutic options based on the current literature.

The spectrum of acquired and familial cold-induced urticaria/urticaria-like syndromes

Acquired cold urticaria syndromes represent one of the more common forms of physical urticaria. The syndromes are heterogenous, and a diagnostic classification is presented to facilitate collation for future studies. Acquired cold urticaria represents an excellent reproducible in vivo model to investigate the mechanisms of urticaria. The discussion includes clinical manifestations, laboratory features, pathogenesis, and management of these disorders. A description of familial types, particularly familial cold auto-inflammatory syndrome (FCAS) that is manifested by cold-evoked signs and symptoms of chronic inflammation, is included. FCAS historically has been included with acquired cold urticaria, even though the exanthem of FCAS is maculopapular caused by leukocytic infiltration. FCAS has become an important investigative syndrome, as it represents a reproducible in vivo model of chronic inflammation.

Urticaria and angioedema: an overview

Persistent or frequent episodes of urticaria are difficult to evaluate and treat. The best test to identify most patients with a specific underlying cause (eg, physical trigger, allergen, systemic disease) likely is the taking of a careful and detailed history and performance of a physical examination by a specialist who is knowledgeable in urticarial disease. Further study of the pathogenesis and treatment of urticaria is crucial. Given the limited efficacy of presently approved antihistamine treatments and the significant side effects of steroids and cyclosporine, there is a pressing need to evaluate other anecdotally supported urticaria treatments in randomized, controlled trials.

Riot control agents: pharmacology, toxicology, biochemistry and chemistry

The desired effect of all riot control agents is the temporary disablement of individuals by way of intense irritation of the mucous membranes and skin. Generally, riot control agents can produce acute site-specific toxicity where sensory irritation occurs. Early riot control agents, namely, chloroacetophenone (CN) and chlorodihydrophenarsazine (DM), have been replaced with 'safer' agents such as o-chlorobenzylidene malononitrile (CS) and oleoresin of capsicum (OC). Riot control agents are safe when used as intended: however, the widespread use of riot control agents raises questions and concerns regarding their health effects and safety. A large margin exists between dosages that produce harassment and dosages likely to cause adverse health effects for modern riot control agents such as CS and dibenz[b,f]1 : 4-oxazepine (CR). Yet, despite the low toxicity of modern riot control agents, these compounds are not entirely without risk. The risk of toxicity increases with higher exposure levels and prolonged exposure durations. Ocular, pulmonary and dermal injury may occur on exposure to high levels of these substances, and exposure to riot control agents in enclosed spaces may produce significant toxic effects. Reported deaths are few involving riot control agents, and then only under conditions of prolonged exposure and high concentrations. Recently, concern has focused on the deaths resulting from law enforcement use of OC, a riot control agent generally regarded as safe because it is a natural product. As with other xenobiotics, not enough is known concerning the long-term/chronic effects of riot control agents. Clearly, there is considerable need for additional research to define and delineate the biological and toxicological actions of riot control agents and to illuminate the full health consequences of these compounds as riot control agents.

Localized heat urticaria: a clinical study using laser Doppler flowmetry

We studied the pathophysiology of localized heat urticaria using laser Doppler flowmetry (LDF) in two patients with this rare disease. In heat challenge tests, performed with different challenge times and temperatures, a heat stimulator with a thermoregulated metal disc was utilized. Immediately after removal of the heat source, cutaneous blood flow (CBF) changes in the tested sites were monitored with LDF. In both patients the increase in (CBF) took place at some intervals after a heat challenge, synchronous with the start of the urticarial response. This interval, or the latency time (LT), showed distinct inverse proportion to the intensity of heat stimuli and was prolonged by effective treatments, such as application of antihistamines and repeated heat exposure by LDF. Therefore, the time of latency might be regarded as a good indicator of the severity of illness and therapeutic effectiveness, and thus might reflect the relationship between the degree of heat stimuli and the releasing process of chemical mediator(s) in patients with localized heat urticaria (LHU).

Localized heat urticaria

Localized heat urticaria is one of the rarest of the physical urticarias, characterized by well-defined urticarial lesions sharply confined to sites of heat exposure. We describe a case of localized heat urticaria in a 40-year-old woman. Because of the rarity of this disorder, much remains to be elucidated. The clinical features, pathogenesis and therapy are reviewed.

Innervation of melanocytes in human skin

Communication between the nervous system and epidermal melanocytes has been suspected on the basis of their common embryologic origin and apparent parallel involvement in several disease processes, but never proven. In this study, confocal microscopic analysis of human skin sections stained with antibodies specific for melanocytes and nerve fibers showed intraepidermal nerve endings in contact with melanocytes. This intimate contact was confirmed by electron microscopy, which further demonstrated thickening of apposing plasma membranes between melanocytes and nerve fibers, similar to synaptic contacts seen in nervous tissue. Since many intraepidermal nerve fibers are afferent nerves that act in a "neurosecretory" fashion through their terminals, cultured human melanocytes were stimulated with calcitonin gene-related peptide (CGRP), substance P, or vasoactive intestinal peptide, neuropeptides known to be present in cutaneous nerves, to examine their possible functions in the epidermal melanin unit. CGRP increased DNA synthesis rate of melanocytes in a concentration- and time-dependent manner. Cell yields after 5 d were increased 25% compared with controls maintained in an otherwise optimized medium. Furthermore, stimulation by CGRP induced rapid and dose-dependent accumulation of intracellular cAMP, suggesting that the mitogenic effect is mediated by the cAMP pathway. These studies confirm and expand a single earlier report in an animal model of physical contact between melanocytes and cutaneous nerves and for the first time strongly suggest that the nervous system may exert a tonic effect on melanocytes in normal or diseased human skin.

Epidermal innervation correlates with severity of photodamage. A quantitative ultrastructural study

Intraepidermal nerve fibers were studied by electron microscopy in chronically photodamaged preauricular skin and in paired sun-protected postauricular sites of 20 Caucasian women aged 56-70 years. As previously reported, basal keratinocytes in the sun-exposed skin showed various degrees of degenerative changes including intracellular vacuolar structures and widened intercellular spaces. Neurites were frequently closely apposed to basal keratinocytes in preauricular sun-exposed skin, but were observed less than 10% as often in sun-protected postauricular skin. When degree of epidermal photodamage was quantified by means of the number of degenerated keratinocytes per 100 keratinocytes in the basal layer, the number of intraepidermal nerve fibers was significantly correlated by linear regression analysis to the severity of epidermal photodamage (r = 0.913) independent of anatomical sites. These results demonstrate for the first time a correlation between degree of epidermal innervation and chronic photodamage and suggest the possibility of neural involvement in the pathophysiology and/or repair of photodamaged skin.

Treatment of cold urticaria

BACKGROUND

The etiology of cold contact urticaria is unknown and the therapy is therefore usually rather disappointing.

METHODS

This study reports therapeutic data on 42 patients with cold urticaria treated with a combination of terbutaline (3 x 5 mg a week, later 3 x 2.5 mg) and aminophylline-containing drugs (3 x 150 mg).

RESULTS

Complete remission of the urticarial response was achieved in 37 of the 42 patients.

CONCLUSIONS

The therapy was tolerated relatively well and the results are promising.

Increased number of immunoreactive nerve fibers in atopic dermatitis

The presence of immunologic markers for neurofilaments, neuropeptides of sensory nerve fibers (Calcitonin gene-related peptide and substance P), for noradrenergic innervation (neuropeptide Y and Tyrosine hydroxylase), and Neuron-specific protein 9.5 was evaluated in frozen tissue sections from normal skin (n = 34) and from skin biopsies manifesting urticaria (n = 6), leukocytoclastic vasculitis (n = 4), systemic lupus erythematosus (n = 23), and atopic dermatitis (n = 40, of which 16 were from lesions induced by epicutaneous atopic allergen patch tests). In some normal skin specimens immunoreactive nerve fibers expressing Neuron-specific protein 9.5 were observed in the epidermis, dermis, and around blood vessels. For the other markers, immunolabeling was mainly observed in the dermis around blood vessels. Neurofilaments, which are scarce in normal skin epidermis, were present in higher density in the epidermis of affected skin in all disease conditions. Biopsies from urticaria and systemic lupus erythematosus showed a decrease in density of fibers immunolabeled for neuropeptides substance P and Calcitonin gene-related peptide and for Neuropeptide Y. In biopsies from skin with atopic dermatitis, an increased density of fibers was observed for all markers except Neuropeptide Y and Tyrosine hydroxylase. In this group, biopsies from positive atopic allergen patch tests showed an enhanced density of fibers labeled by antibody to Neuron-specific protein 9.5 and a lower density in labeling for Tyrosine hydroxylase. The data indicate a potential role of innervation and neuropeptides in dermatoses like atopic dermatitis.

Urticaria: current therapy

Although the ideal treatment for urticaria is identification and removal of its cause, no underlying cause can be discerned in the majority of instances. The chief clinical problem is the treatment of chronic idiopathic urticaria. H1-receptor antagonists are the major class of therapeutic agents used in the management of chronic idiopathic urticaria. The H1 antagonists have been divided into subgroups based on their chemical structure. The second-generation H1 antagonists now available are particularly advantageous for individuals who must remain alert while working. Terbutaline, a beta-adrenergic agonist, is of occasional benefit as an adjunct therapy in combination with an H1 antagonist. The oral administration of disodium cromoglycate is ineffective in patients with chronic idiopathic urticaria, although a few individuals with urticaria caused by food allergy may respond to this drug. It is best to avoid repeated injections of epinephrine and the systemic administration of corticosteroids. Urticaria has a capricious course: it may respond to the administration of placebos or it may resolve spontaneously. About 50% of the patients with urticaria are free of lesions within 1 year, but 20% continue to have episodes for more than 20 years.

Angiotensin-converting enzyme inhibitors and their influence on inflammation, bronchial reactivity and cough. A research review

Synthetic orally active angiotensin-converting enzyme (ACE) inhibitors have been successfully used in the treatment of congestive heart failure and hypertension, particularly in hypertensive subjects with increased renin-angiotensin-aldosterone-system activity. Adverse skin reactions, angioneurotic oedema and rapidly decreasing lung function in asthmatics have been reported following medication with ACE inhibitors. Furthermore, these drugs have been associated with a persistent dry cough in subjects without previous known bronchial hyper-reactivity. There is reason to believe that an ACE inhibitor-induced cough is due to an increased inflammatory state in the airways of susceptible individuals, and that this cough might thereby have pathophysiological features in common with the cough seen as an early symptom of asthma. All inflammatory responses, wheal and flare reactions, infiltration of neutrophils, eosinophils, basophils and monocytes were enhanced by ACE inhibitors. A dose-response relationship for the proinflammatory effect of the ACE inhibitor has been demonstrated.

The human skin mast cell

The abundance of mast cells in human dermis, together with their ability to release a variety of vasoactive and pro-inflammatory mediators following cross-linkage of their cell-surface receptors for IgE, enables these cells to provide an effective defence mechanism within this organ. A similar defensive function is attributed to mast cells of other human organs such as intestine and lung which are in contact with the external environment and therefore susceptible to infiltration by foreign allergens and micro-organisms. However, mast cells of the skin apparently differ from those present in lung and intestine in being activated for histamine release by a variety of endogenous neuropeptides which stimulate the rapid release of histamine in the virtual absence of eicosanoids. This would provide a mechanism of neurogenic control of a variety of homeostatic functions such as blood flow, angiogenesis and fibroblast proliferation. Such processes would aid in the remodelling of tissue during wound healing, and increased numbers of mast cells have been noted around healing wounds of rat skin and areas of developing fibrosis. Neuropeptides modulate the activity of a variety of immuno-competent leucocytes including macrophages, monocytes and lymphocytes. The findings that skin mast cells are activated by neuropeptides suggest that these cells may also be included amongst those involved in neuro-immune interactions. Activation of skin mast cells by non-immunological stimuli may contribute to the aetiology of some forms of skin disease. Patients with chronic idiopathic urticaria appear to have enhanced vascular responsiveness to intradermal injections of the histamine liberator codeine suggesting that this disease may involve hyper-responsiveness of their mast cells to endogenous non-immunological stimuli. The findings of large increases in histamine accompanied by small increases in PGD2 in venous effluent of thermally challenged limbs of patients with cold- or heat-induced urticaria may suggest that their mast cells had been activated by a non-immunological stimulus. However, the interpretation of results gained using such relatively complex in-vivo systems are difficult, as the cellular origin of the detected mediators is by no means clear. However, it is hoped that in the future the alliance of newly developed in-vitro techniques to investigate mast cell function together with in-vivo methods to investigate their interaction with elements in their tissue environment will greatly increase our understanding of the role of the human skin mast cell in health and disease.

Calcitonin gene-related peptide immunoreactivity in prurigo nodularis: a comparative study with neurodermatitis circumscripta

Eight patients with intensely pruritic lesions of chronic idiopathic prurigo nodularis and three patients with neurodermatitis circumscripta were investigated using the indirect immunofluorescence method. Results showed similarities in epidermal hyperplasia but not in nerve proliferation and neuropeptide immunoreactivity. Increased numbers of calcitonin gene-related peptide (CGRP) and substance P immunoreactive nerve fibre bundles were detected in specimens taken from prurigo nodularis lesions, but no increased immunoreactivity could be seen in specimens taken from patients having neurodermatitis circumscripta compared to normal skin. The neuropeptides, CGRP and substance P, may be responsible for the intense itching of prurigo nodularis lesions.

Antidromic vasodilatation and neurogenic inflammation

Antidromic stimulation of the lumbosacral dorsal roots of the rat 1.) evokes a long-lasting increase in cutaneous microcirculation of the paw as detected by the laser Doppler flowmeter, and 2.) induces plasma extravasation in the innervated skin areas and various pelvic organs. Both responses are strongly inhibited or abolished by systemic or local capsaicin desensitization. Cutaneous vasodilatation is evoked already by 1-2 pulses. Desensitization of the volar skin of the forearm abolishes the flare reaction both in the "afferent" and "efferent" side of the axon reflex. A dual sensory-efferent function for capsaicin-sensitive nociceptors is suggested. This local neuroregulatory mechanism mediates neurogenic inflammation, cutaneous vasodilatation and flare reaction not only when the receptors are activated by antidromic stimuli, but also when their orthodromic excitation by chemical means occurs.

The sensory-efferent function of capsaicin-sensitive sensory neurons

Capsaicin-sensitive sensory neurons convey to the central nervous system signals (chemical and physical) arising from viscera and the skin which activate a variety of visceromotor and neuroendocrine reflexes integrated at various levels (intramurally in peripheral organs, at level of prevertebral ganglia, spinal and supraspinal level). Much evidence is now available that peripheral terminals of certain sensory neurons, widely distributed in skin and viscera have the ability to release, upon adequate stimulation, their transmitter content. In addition to the well-known "axon reflex" arrangement, the capsaicin-sensitive sensory neurons have the ability to release the stored transmitter also from the same terminal which is excited by the environmental stimulus. The efferent function of these sensory neurons is realized through the direct and indirect (i.e. mediated by activation of other cells) effects of released mediators. The action of released transmitters on postjunctional elements covers a wide range of effects which may have a physiological or pathological relevance. Development of drugs capable of controlling the sensory-efferent functions of the capsaicin-sensitive sensory neurons represent a new and very promising area of research for pharmacological treatment of various human diseases.

Occurrence of substance P, vasoactive intestinal peptide, and calcitonin gene-related peptide in dermographism and cold urticaria

Substance P (SP), calcitonin gene-related peptide (CGRP), and vasoactive intestinal peptide (VIP) were assayed in lesions and normal skin of patients with dermographism and cold urticaria utilizing suction-induced blisters. There was no difference in SP and VIP concentrations between challenged and control skin of urticaria patients. On the whole, however, the concentration of both neuropeptides, and VIP in particular, was higher in the urticaria patients than in control subjects. CGRP levels were not increased. SP and VIP in blood samples from veins draining challenged skin areas were below the detection limit. It is concluded that SP and VIP may potentiate histamine in wheal formation and thus contribute to the increased reactivity of the skin to trauma and temperature changes in patients with physical urticaria.

Household treatment for "chile burns" of the hands

In New Mexico, chile peppers (Capsicum annum) are prepared by roasting and manually removing the skin from the fruit. Peeling is often done barehanded and may cause prolonged burning pain, irritation, and erythema but not vesication. In a survey of elderly Hispanic women, treatment with oils or cool tap water were frequently used home remedies. Twenty female subjects immersed their hands in a standardized slurry of green chile for 40 minutes, afterwards one hand was placed in cool tap water and the other in vegetable oil for a total of 75 minutes. Pain was scored using a visual analog scale while the hands were immersed in the chile slurry, test baths, and after drying. The difference in pain score was calculated for each subject. Analysis was by pooled regression. Cool tap water immersion initially provided more relief while vegetable oil provided better long-term relief from the pain of "chile burns".

Cold urticaria. Clinical findings in 220 patients

Patients with cold urticaria, a total of 220, were studied in Finland. Sixty-three percent of the patients were female. The diagnosis was based on a positive ice cube test in 90% of cases, and the other cold tests were needed to certify the diagnosis for the remainder of patients. The mean age at the onset of the disease was 25.1 years (range, 1-74), and the mean duration of symptoms was 6.3 years (range, 3 weeks to 37 years). Cold urticaria symptoms had disappeared in fifty-three patients (24%), but there was a recurrence of the disease in twelve. Idiopathic (primary acquired) cold urticaria was present in 96% of the patients. Only two patients had a secondary acquired cold urticaria. Two patients had cold-induced, "cholinergic" urticaria, and four patients had a delayed type of cold urticaria. Twenty-one percent of the patients had dermatographism, 8% had cholinergic urticaria, and two patients (1%) had heat urticaria concurrently with cold urticaria.

Human assay for identifying substances which induce non-allergic contact urticaria: the NICU-test

The problems of non-immunologic contact urticariogens are addressed from various points of view. A new test for evaluating substances which may cause non-immunologic contact urticaria in humans, the NICU test, is introduced. Characteristic data of widely known contact urticariogens are given.