Mast cells and T lymphocytes in chronic urticaria

Chronic urticaria and the pathogenic role of mast cells

The signs and symptoms of chronic urticaria (CU) are caused by the activation and degranulation of skin mast cells (MCs). Recent studies have added to our understanding of how and why skin MCs are involved and different in CU. Also, novel and relevant mechanisms of MC activation in CU have been identified and characterized. Finally, the use of MC-targeted and MC mediator-specific treatments has helped to better define the role of the skin environment, the contribution of specific MC mediators, and the relevance of MC crosstalk with other cells in the pathogenesis of CU. Here, we review these recent findings and their impact on our understanding of CU, with a focus on chronic spontaneous urticaria (CSU). Also, we highlight open questions, issues of controversy, and unmet needs, and we suggest what studies should be performed moving forward.

The Role of Bradykinin Receptors in the Etiopathogenesis of Chronic Spontaneous Urticaria

Background and Objectives: Chronic spontaneous urticaria (CSU) is a distressing skin condition, which manifests as red, swollen, itchy, and sometimes painful hives or wheals appearing on skin. Recently, CSU has been associated with bradykinin release, which was previously discovered to be the main trigger of hereditary angioedema attacks. To study the role of bradykinin receptors 1 (BR1) and 2 (BR2) in the etiopathogenesis of CSU. Materials and Methods: A total of 60 individuals, 30 patients with CSU and 30 healthy subjects, were recruited to the study. CSU was diagnosed in accordance with the standardized protocol of dermatological assessment of skin symptoms. The level of bradykinin receptors was determined in populations of CD3⁺, CD4⁺, and CD8⁺ lymphocytes as well as in CD14⁺⁺CD16⁻, CD14⁺⁺CD16⁺ and CD14⁺CD16⁺ monocytes. In addition, urticaria activity score summed over 7 days (UAS-7) was assessed and correlated with BR1 and BR2 expression. Results: A statistically significant higher concentration of BR1 expression in lymphocytes was found in patients with CSU, compared to the control group (p < 0.001). Moreover, a statistically significant positive correlation was observed between UAS-7 and BR1/BR2 expression in CD14⁺⁺CD16⁻ cells (p = 0.03, R = 0.4). Conclusions: Bradykinin receptors are elevated in selected populations of lymphocytes in symptomatic CSU patients compared to healthy controls, indicating their role in the etiopathogenesis of the disease.

SELE Downregulation Suppresses Mast Cell Accumulation to Protect against Inflammatory Response in Chronic Idiopathic Urticaria

BACKGROUND

Chronic idiopathic urticaria (CIU) represents a common skin disorder often characterized by mast cell activation and secretion of histamine and other proinflammatory factors. E-selectin (SELE) has been implicated in the pathogenesis of common inflammatory cutaneous disorders, while the role of SELE in CIU is yet to be fully understood. Thus, we aimed to investigate the mechanism by which SELE influences CIU in connection with the involvement of mast cells.

METHODS

SELE expression was measured in blood samples obtained from CIU patients and normal individuals. A CIU mouse model was subsequently established by intradermally injecting a normal saline solution with ovalbumin IgE antiserum into the mice. Loss- and gain-of-function investigations were conducted on the mouse models. The number of degranulated mast cells and the amount of histamine release in vitro were determined. The levels of SELE, tumor necrosis factor (TNF)-α, homologous restriction factor (HRF), and interleukin (IL)-6 levels were determined.

RESULTS

The CIU clinical samples exhibited upregulated SELE, while the CIU mice showed increased mast cell degranulation and an increased rate of histamine directional release, as well as an elevated expression of SELE, TNF-α, HRF, and IL-6. SELE silencing was found to decrease the number of degranulated mast cells and reduce the rate of histamine directional release, along with suppressed TNF-α, HRF, and IL-6 expression, in the serum of CIU mice. Ketotifen was observed to rescue the increased expression of TNF-α, HRF, and IL-6 caused by SELE overexpression.

CONCLUSIONS

This study highlights the potential of SELE downregulation to repress inflammatory factor secretion caused by the accumulation of mast cells, which ultimately inhibits the development of CIU.

Single nucleotide polymorphisms of IL-2, but not IL-12 and IFN-γ, are associated with increased susceptibility to chronic spontaneous urticaria

BACKGROUND

A clear picture of interaction of Th1/Th2 cytokines in pathogenesis of chronic spontaneous urticaria (CSU), remains elusive. Impaired IFN-γ production and decreased levels of IL-2 have been reported. The aim of this study was to evaluate the association of Th1 cytokines; IL-2, IL-12 and IFN-γ polymorphisms with CSU.

METHODS

90 patients with CSU and 140 age-sex matched subjects were included in this study. DNA samples were evaluated through PCR-SSP assay in order to detect single nucleotide polymorphisms of IL-12 (A/C -1188) or (rs3212227), IFN-γ (A/T UTR5644) or (rs2069717) and IL-2 (G/T -330 and G/T +166) or (rs2069762 and rs2069763).

RESULTS

G allele at -330 at promoter region of IL-2 gene was overrepresented in CSU. Heterozygotes (GT) at this locus and heterozygotes at +166 of IL-2 gene (GT) were more prevalent in CSU group. Additionally, the haplotype GT for loci -330 and +166 of IL-2 gene was powerfully associated with CSU (OR (95%CI)=57.29 (8.43-112.7)).

CONCLUSIONS

SNP at position -330 and +166 of IL-2 gene are differently expressed in CSU. The haplotype GT of IL-2 at -330 and +166 might confer vulnerability to a number of immunological disorders in Iranian region.

Cellular Infiltrate and Related Cytokines, Chemokines, Chemokine Receptors and Adhesion Molecules in Chronic Autoimmune Urticaria: Comparison between Spontaneous and Autologous Serum Skin Test Induced Wheal

In recent years, the demonstration of circulating functional autoantibodies against the high affinity IgE receptor or against IgE themselves in about one-third of patients with chronic idiopathic urticaria has suggested that an autoimmune mechanism might be involved in the pathogenesis of the disease [the so-called chronic autoimmune urticaria (CAIU)]. In this study we compare findings from serum-induced and spontaneous wheals with regard to immunohistochemical markers of disease activity and discuss whether autologous serum skin test (ASST) may be regarded as an in vivo experimental model of the physiological stimulus causing urticaria skin condition, or if it does not reproduce the whole of the mechanisms operating in the development of spontaneous wheals. By means of immunohistochemical technique, we analyzed specimens from just-developed spontaneous wheals and from serum-evoked wheals of six CAIU patients, to glean information on cellular infiltrate and related cytokines, chemokines, chemokine receptors and adhesion molecules. According to the results of our study, spontaneous urticaria lesions seem to be sustained by a characteristic inflammation pattern where neutrophils, adhesion molecules, IL-8 and chemokine receptors play a main role in flogosis triggering and, consequently, disease development. On the contrary, ASST-induced wheals seem to imply different activities mainly represented by basophil granulocytes and related molecules, i.e. IL-4. Although it represents an efficacious diagnostic instrument to screen CAIU patients, ASST is not an exhaustive model of the many immunopathogenic pathways operating in the development of urticaria lesions, especially with regard to systemic activation networks.

Narrowband ultraviolet B (311 nm, TL01) phototherapy in chronic ordinary urticaria

BACKGROUND

Chronic ordinary urticaria (COU) can severely reduce quality of life and be difficult to control. Ultraviolet (UV) A and UVB phototherapy has been reported to decrease the release of histamine from either mast cells and/or basophils. Previous small studies have suggested that UVB phototherapy is a good alternative treatment for COU.

OBJECTIVES

The purpose of this study was to assess the efficacy of narrow-band UVB (NB-UVB) phototherapy for COU.

MATERIALS AND METHODS

Twenty-two patients (three male, 19 female) received NB-UVB phototherapy. These patients had not responded to at least two H1 antihistamines, and most had been treated with a variety of antihistamine combinations. Clinical responses were assessed according to an outcome scoring scale. During both visits, patients were administered the following: the visual analogue scale (VAS) on present pruritus and/or whealing; chronic urticaria impact on patients' quality of life according to the interference with daily activities, quality of sleep, and flare-up rates.

RESULTS

The median number of treatments was 31.4 (9-44), and the mean top dose was 9.46 J/cm(2) (1.1-16.4 J/cm(2)). NB-UVB treatment led to clearance in 10 patients (45%), marked improvement in five (22%), and moderate improvement in seven (31%) patients according to an outcome scoring scale. Mild side effects were observed in two patients. Six patients who cleared or observed marked improvement remained clear at follow-up for a period of six months to one year, and other patients had a few recurrent lesions that did not need retreatment. For VAS scores and total chronic urticaria impact on patients' quality of life scores, the differences between baseline and after treatment scores were significantly lower (P < 0.001, P < 0.001, respectively).

CONCLUSION

Narrow-band UVB (NB-UVB) therapy is an effective, well-tolerated treatment option in second-line therapy for COU. This therapy can lead to subjective relief of pruritus and whealing and objective reduction of whealing. Further larger studies with longer follow-up periods are necessary to determine the proper clinical response and long-term complications of this therapy in COU.

Other Allergic Skin Disorders

In this chapter we discuss allergic skin disorders other than atopic dermatitis (AD): the urticaria-angioedema syndrome, allergic contact dermatitis (ACD), protein contact dermatitis (PCD), phytodermatitis, allergic photodermatitis and allergic vasculitis.

Progress and challenges in the understanding of chronic urticaria

: Chronic urticaria is a skin disorder characterized by transient pruritic weals that recur from day to day for 6 weeks or more. It has a great impact on patients' quality of life. In spite of this prevalence and morbidity, we are only beginning to understand its physiopathology and we do not have a curative treatment. Moreover, a patient with chronic urticaria may undergo extensive laboratory evaluations seeking a cause only to be frustrated when none is found. In recent years there have been significant advances in our understanding of some of the molecular mechanisms responsible for hive formation. The presence and probable role of IgG autoantibodies directed against epitopes expressed on the alpha-chain of the IgE receptor and to lesser extent, to IgE in a subset of patients is generally acknowledged. These autoantibodies activate complement to release C5a, which augments histamine release, and IL4 and leukotriene C4 are released as well. A perivascular cellular infiltrate results without predominance of either Th1 or Th2 lymphocyte subpopulations. Basophils of all chronic urticaria patients (autoimmune or idiopathic) are hyperresponsive to serum, regardless of source, but poorly responsive to anti IgE. In this review we will summarize the recent contributions to this field and try to provide insights to possible future directions for research on this disease.

Bullous delayed pressure urticaria: pathogenic role for eosinophilic granulocytes?

Bullous delayed pressure urticaria (DPU) is a rare variant of DPU. Treatment of DPU is difficult and the underlying pathogenic mechanism of DPU remains elusive. We report a 72-year-old man with DPU and associated chronic urticaria as well as delayed urticarial dermographism. Pressure challenge gave rise to a deep weal covered by multiple vesicles and bullae after 24 h. Histological examination of a skin biopsy specimen obtained 24 h after pressure challenge demonstrated intraepidermal bullae filled with eosinophils accompanied by a dense, predominantly eosinophilic infiltrate in the dermis. Whereas the numbers and morphology of mast cells were unaltered, the extracellular deposition of eosinophil cationic protein revealed evidence for eosinophil activation. Concomitantly, both CD4+ and CD8+ T lymphocytes were present in the infiltrate and expressed interleukin 5. As bullous DPU may represent the maximal variant of DPU, the investigation of the cellular infiltrate and the chemokines/cytokines released may reveal potential pathogenic mechanisms. A possible effector role of eosinophilic granulocytes, T-cell subsets and mast cells is discussed.

Chronic idiopathic urticaria: infiltrating cells and related cytokines in autologous serum-induced wheals

The term chronic autoimmune urticaria (CAIU) is used for chronic urticaria in subjects who present a whealing response to the intradermal injection of autologous serum, suggesting the presence of pathogenic antibody activities. In this study, we examined 28 chronic urticaria subjects with positive autologous serum skin test (ASST), all of whom presented autologous serum-induced lesions at different evolutive stages. Punch biopsies were taken from lesional skin of six subjects at 10', eight subjects at 30', six subjects at 60', and four subjects each at 24 and 48 h. Immunological studies focussed on infiltrating cell immunophenotype and related cytokines, chemokines and chemokine receptors, adhesion molecules. Immunohistochemical staining was performed to measure expression of CD3, CD4, CD8, tryptase, eosinophil cationic protein, myeloperoxidase, basophil granular protein, IL-4, IL-5, IL-8, CCR3 and CXCR3, ICAM-1, VCAM and ELAM. Control staining was done on unaffected skin from the patients and normal skin from four healthy donors. The main infiltrating population was represented by neutrophils, seen focally in both unaffected skin (P = 0.001) and healthy controls (P = 0.003). IFN-gamma and IL-5 were expressed focally in autologous wheals. Significant staining for IL-4 was seen at 30'. CCR3 and CXCR3 were expressed less in autologous wheals than in uninvolved skin (P < 0.0001; P = 0.002). Cellular adhesion molecules (CAMs) reached their highest expression at 30' and 60' in induced lesions, and they showed strong expression also in unaffected skin (ICAM-1: P < 0.0001). Our data show that the immunoinflammatory features of ASST-induced wheals involve a prevalent role of lymphocytes (with a mixed Th1/Th2 response), with strong neutrophil infiltration and activity and involvement of the chemokine pathway. We interpreted the finding of inflammatory cells and mediator up-regulation in uninvolved CIU skin as a sign of prolonged and widespread "urticarial status".

Infiltrating cells and related cytokines in lesional skin of patients with chronic idiopathic urticaria and positive autologous serum skin test

In approximately one-third of patients with chronic idiopathic urticaria (CIU), autoantibodies against the high-affinity IgE receptor and/ or against IgE can be detected and a wheal-and-flare response can be provoked by the intradermal injection of autologous serum (ASST). In this study we aimed to further characterize the inflammatory response observed in the subgroup of CIU patients with positive ASST and serum-evoked histamine-release in vitro from basophils in comparison with unaffected skin and healthy donors. An immunohistochemical analysis of infiltrating cells (CD4, MPO, EG1, EG2, tryptase), cytokines (IL-4, IL-5, IFN-gamma), chemokines and chemokine receptors (IL-8, CCR3, CXCR3), and adhesion molecules (ICAM-1, VCAM-1, ELAM-1) was performed on seven selected patients (four males and three females; median age: 45 years; range: 22-57) and five healthy donors. Cytokine evaluation was also performed in five psoriatic patients to obtain an additional control. In spontaneous wheals we observed an increased number of CD4+ T lymphocytes when compared with the controls, and an increased number of neutrophils and eosinophils, whereas mast cells did not show a significant variation. A significant expression for IL-4 and IL-5 could only be observed in lesional skin, while IFN-gamma showed a slight expression in the same site. Chemokine receptors CCR3 and CXCR3 did not show a defined polarized response in either lesional or unaffected skin. An increased expression of all cellular adhesion molecules (CAMs) studied was detected in spontaneous wheals. The lack of a significant difference in the expression of tryptase + mast cells, T lymphocytes, IL-8, CXCR3 and CCR3, a few CAMs between the lesional and unaffected skin of CIU patients suggests a wide immunological activation that involves not only lesional tissues, but possibly extends to the whole of the skin's immune system.

Urticaria and urticarial vasculitis

Urticaria and urticarial vasculitis may be triggered by allergens, infection, autoimmunity and other immunological conditions. Careful evaluation, skin biopsy and specific laboratory tests can assist in diagnosis. The appropriate use of antihistamines, glucocorticoids, and other immunomodulators are discussed.

Decreased cutaneous expression of stem cell factor and of the p75NGF receptor in urticaria

BACKGROUND

Mast cells, the main effector cells in urticaria, have been reported to be increased in number in lesional and nonlesional skin of urticaria patients, but the underlying mechanisms have so far not been studied. Serum NGF has however, been reported to be increased in urticaria.

OBJECTIVES

We have therefore explored the potential involvement of known mast cell growth modulating factors in urticaria.

METHODS

Tissue sections from patients with different types of urticaria and healthy controls were studied for the immunohistochemical expression of known mast cell growth factors (stem cell factor, SCF; nerve growth factor, NGF), of the inhibitory granulocyte-macrophage colony-stimulating factor (GM-CSF), and of the corresponding receptors, using the alkaline phosphatase-antialkaline phosphatase technique.

RESULTS

Compared to skin of normal controls, staining for SCF, but not for NGF and GM-CSF, was significantly decreased in epidermis, endothelium and perivascular cells in lesional and nonlesional skin of all urticarias. On separate analysis of urticaria subtypes, decreased expression reached significance only in delayed pressure urticaria. Expression of the p75NGF receptor (p75NGFR) was also significantly decreased on endothelium and on perivascular cells of lesional and nonlesional skin in all urticarias. On evaluation of serial sections, p75NGFR expression was also decreased on c-Kit positive dermal mast cells. In contrast, expression of the NGF receptor tyrosine kinase and of the SCF and GM-CSF receptors was unchanged.

CONCLUSIONS

These findings show that SCF and p75NGFR are selectively and systemically down-regulated in the skin of urticaria patients and may represent a negative feedback to increased mast cell reactivity and proliferation.

Evaluation of inflammatory parameters in physical urticarias and effects of an anti-inflammatory/antiallergic treatment

BACKGROUND

Physical urticaria (PU) includes a heterogeneous group of urticarias whose etiopathogenic aspects are still obscure and whose therapeutical management is often difficult. We have previously demonstrated the efficacy of a sequential treatment with nimesulide, a unique nonsteroidal anti-inflammatory drug, and ketotifen in various forms of PU.

METHODS

The expression of some inflammatory parameters was evaluated in 10 patients affected with some forms of PU. In particular, serum levels of interleukin (IL)-4, IL-1beta, tumor necrosis factor (TNF)-alpha, adhesion molecules (sELAM, sICAM-1 and sVCAM), soluble receptors (sIL-2R, sCD30, sCD23) and IgE were assessed. Moreover, the cutaneous expression of IL-1beta, TNF-alpha and ICAM-1 was studied on biopsy specimens taken from nonlesional skin of patients. The same parameters were further evaluated in both skin and serum following treatment with nimesulide and ketotifen, in order to better understand the possible effects of these agents on the inflammatory network of PU.

RESULTS

Before therapy we could detect significantly higher serum levels of IL-1beta and TNF-alpha (P < 0.001) and of circulating adhesion molecules in comparison with controls (sELAM, sICAM: P < 0.001; sVCAM: P < 0.02); after treatment, a significant reduction of each was observed (P < 0.05). Simultaneously, a high expression of IL-1beta, TNF-alpha and ICAM-1 was detected in all skin specimens at the baseline, with a relevant decrease following therapy.

CONCLUSIONS

These results confirm the therapeutical value of treatment with nimesulide and ketotifen in PU and suggest that these agents are able to reduce the release and the expression of some inflammatory molecules that are up-regulated in PU.

Delayed pressure urticaria

Delayed pressure urticaria is a physical urticaria where erythematous, often painful swellings occur at sites of sustained pressure on the skin, after a delay of several hours. If sought, it is present in up to 40% of patients with ordinary chronic "idiopathic urticaria" to a varying degree. Compared with other urticarias, the pressure-induced lesions impair the quality of life of patients most severely. The pathogenesis is not well characterized, but whealing is dependent on mast cell activation, with the histology of lesions also showing a deep dermal inflammatory infiltrate of neutrophils and eosinophils, without vasculitis. Treatment of delayed pressure is generally unsatisfactory, and is often resistant to antihistamine and a range of anti-inflammatory medication. Oral steroids, although the most effective therapy, are unsuitable for long-term use. Delayed pressure urticaria may persist for many years, and improved or novel methods of management are under investigation.

Mechanisms underlying urticaria

Urticaria, a clinically distressing disorder, is dermal oedema resulting from vascular dilatation and leakage of fluid into surrounding tissue, often in response to histamine (and other mediators) released from mast cells. A clear history of events surrounding the onset, together with laboratory investigations, in some cases allows us to find a cause and eliminate it.

Cutaneous inflammatory cell infiltrate in chronic idiopathic urticaria: comparison of patients with and without anti-FcepsilonRI or anti-IgE autoantibodies

BACKGROUND

Previous studies defining the histopathologic features of patients with chronic idiopathic urticaria (CIU) were performed on wheals of uncertain duration and before the identification of functional autoantibodies against FcepsilonRI and/or IgE, now known to be present in approximately 30% of patients with CIU.

OBJECTIVE

We sought to determine the timing of the inflammatory infiltrate in the wheals of patients with CIU and to detect differences between patients with and without autoantibodies.

METHODS

Immunohistochemistry was used to identify neutrophils (neutrophil elastase), T lymphocytes (CD3), and activated eosinophils (EG2) in biopsy specimens from uninvolved skin and wheals present for less than 4 hours and greater than 12 hours in 22 patients with CIU, as well as in biopsy specimens from the skin of 12 healthy control subjects. Patients were identified as having functional autoantibodies on the basis of their serum-evoked histamine release in vitro from the basophils of 2 healthy donors.

RESULTS

EG2(+), neutrophil elastase+, and, to a lesser extent, CD3(+) cells were found in greater numbers in wheals undergoing biopsy at less than 4 and greater than 12 hours than in uninvolved skin (P <.05). Patients without autoantibodies (n = 12) had significantly more EG2(+) cells in wheals of greater than 12 hours' duration than patients with autoantibodies (n = 10; P =.02). There was no other difference between patients with and without autoantibodies in the cutaneous cellular infiltrate.

CONCLUSION

Neutrophil and eosinophil accumulation occurs early in the evolution of a wheal in patients with CIU, but eosinophil activation may occur later or be more persistent in patients without autoantibodies.

Cutaneous responses to substance P and calcitonin gene-related peptide in chronic urticaria: the effect of cetirizine and dimethindene

BACKGROUND

Neuropeptides appear to participate in the pathogenesis of chronic urticaria. The purpose of this study was to investigate the cutaneous responses to substance P (SP) and calcitonin gene-related peptide (CGRP) in delayed pressure urticaria patients (DPUpt) and chronic idiopathic urticaria patients (CIUpt) compared to healthy adults (HA), and also to evaluate the effect of H1-antagonists on these responses.

METHODS

Wheal (W) and flare (F) reactions to intradermally (ID) injected SP, CGRP, histamine (H), and diluent controls were evaluated in nine CIUpt, nine DPUpt, and nine HA at 3, 7, 15, 30, 60, and 120 min after injection. Maximal W and F, area under curve (AUC), and time of W and F disappearance were calculated at baseline and 4 h after a single dose of 20 mg cetirizine (Ce), 4 mg dimethindene (Di), or placebo (P), in a double-blind, placebo-controlled (DBPC), crossover, randomized study.

RESULTS

CIUpt exhibited enhanced and longer lasting W reactions to SP and CGRP (AUC: P<0.05) than HA; SP- and CGRP-induced F (at maximal concentration) were larger and longer lasting in CIUpt than in HA (P<0.003 and P = 0.004, respectively). In the DPU group, SP-induced W and F responses were intermediate in magnitude compared to CIUpt and HA. In HA, SP-induced flares were significantly suppressed only by Ce (P<0.020), while both Ce and Di affected SP-induced W and F in the two patient groups (P<0.05). CGRP-induced flare inhibition by the two H1-antagonists was also greater in the urticaria patient groups than in HA.

CONCLUSIONS

CIUpt and, to a lesser extent, DPUpt showed enhanced SP- and CGRP-induced W and F reactions. CGRP elicited an immediate W and F response, followed by prolonged erythema. H1-antagonists partially affected W and F reactions to SP and only the F response induced by CGRP; this effect was more pronounced in the urticaria patient groups than in HA. Overall, W and F cutaneous responses to SP were suppressed to a greater extent by Ce than Di.