Co-occurrence of IgE and IgG autoantibodies in patients with chronic spontaneous urticaria.

Chronic spontaneous urticaria (CSU) pathogenesis shows a complex and still unclear interplay between immunoglobulin (Ig)G- and IgE-mediated autoimmunity, leading to mast cell and basophil degranulation and wheal formation. The objective of this study was to evaluate at the same time IgE- and IgG-reactivity to well recognized and recently reported autoantigens in CSU patients, and to assess the effects of such reactivity on response to the anti-IgE monoclonal antibody omalizumab. Twenty CSU patients underwent omalizumab treatment. Urticaria activity score 7 (UAS7) was recorded at baseline and at different drug administration time-points for categorizing early-, late- or non-responders. At baseline, sera from the 20 patients and from 20 controls were tested for IgE and IgG autoantibodies to high- and low-affinity IgE receptors (FcεRI and FcεRII), tissue factor (TF) and thyroglobulin (TG) by immunoenzymatic methods. Antibody levels were compared with those of controls and analysed according to response. Eighteen patients were omalizumab responders (11 early and seven late), while two were non-responders. More than 50% of patients had contemporary IgE and IgG to at least to one of the four different autoantigens. Late responders showed higher levels of both anti-TF IgE and IgG than early responders (P = 0·011 and P = 0·035, respectively). Twenty-five per cent of patients had levels of anti-FcεRI IgE, exceeding the upper normal limit, suggesting that it could be a novel auto-allergen in CSU. In CSU, there is an autoimmune milieu characterized by the co-existence of IgE and IgG autoantibodies to the same antigen/allergen, particularly in late responders to omalizumab, possibly explaining the slower response.

Autoinflammation in pyoderma gangrenosum and its syndromic form (pyoderma gangrenosum, acne and suppurative hidradenitis).

BACKGROUND: Pyoderma gangrenosum (PG) is a rare skin disease characterized clinically by ulcers with undermined borders, and histologically by neutrophil-rich infiltrates. PG may occur alone, in syndromic forms or associated with systemic diseases, such as inflammatory bowel disease and haematological or rheumatological disorders. OBJECTIVES: To determine a specific genetic background related to autoinflammation for PG. METHODS: We assessed autoinflammation by evaluating the cytokine profile and genes involved in classic autoinflammatory diseases in 13 patients with PG and in seven patients with the syndromic form, known as PASH (pyoderma gangrenosum, acne and suppurative hidradenitis). RESULTS: In skin samples, the expression of interleukin (IL)-1ß and its receptors, IL-17 and its receptor, and tumour necrosis factor-α and its receptors were significantly higher in both PG (P = 0·001) and in PASH (P < 0·001) than in controls. The chemokines IL-8; chemokine (C-X-C motif) ligand 1/2/3; chemokine (C-X-C motif) ligand 16; and RANTES (regulated on activation, normal T-cell-expressed and secreted) were also overexpressed. Cases of PG and PASH showed mutations in the autoinflammatory genes MEFV, NLRP3, NLRP12, NOD2, LPIN2 and PSTPIP1. CONCLUSIONS: Overexpression of cytokines/chemokines, along with genetic changes, supports the hypothesis that PG and its syndromic form, PASH, are a spectrum of polygenic autoinflammatory conditions.

Involvement of the IgE-basophil system and mild complement activation in haemophilia B with anti-factor IX neutralizing antibodies and anaphylaxis.

INTRODUCTION: Patients with haemophilia B who develop factor IX (FIX) neutralizing antibodies (inhibitors) after FIX infusion are at high risk of hypersensitivity reactions upon FIX re-exposure, but the underlying mechanisms are incompletely understood. AIM: To investigate biomechanisms of FIX hypersensitivity. METHODS: A cellular antigen stimulation test (CAST) was employed to evaluate leukotriene C4 (LTC4) release from basophils stimulated by FIX in three treated children with haemophilia B, one of whom developed FIX inhibitor and experienced anaphylaxis following FIX re-exposure. Anti-FIX IgE and IgG antibodies and markers of complement activation (C5b9, C3d and iC3b) were measured in plasma, the last also after FIX infusion. Ten healthy children served as controls. RESULTS: The patient who developed anti-FIX inhibitors and anaphylaxis had a nonsense mutation in FIX gene (p.Arg298Stop) and, compared to controls, had higher plasma levels of specific anti-FIX IgE (2.285 vs 0.084 OD492 nm ), with marked LTC4 release from his FIX-stimulated basophils (519.8 vs 39.9 pg/mL). Further, he had higher plasma levels of anti-FIX IgG of all the four subclasses (total IgG 1.180 vs 0.120 OD492 nm ) with FIX neutralizing activity (1.5 BU); mild complement activation occurred during FIX-induced anaphylaxis (C5b9 increased from 258.5 to 351.1 ng/mL). The same parameters were normal in the two patients who tolerated FIX infusion. CONCLUSION: In the patient with haemophilia B who experienced anaphylaxis after FIX, but not in the patients with haemophilia B who tolerated FIX, the CAST assay showed FIX-induced LTC4 release, which was associated with high plasma levels of specific anti-FIX IgE and IgG antibodies.

Pyoderma gangrenosum and its syndromic forms: evidence for a link with autoinflammation.

Pyoderma gangrenosum is a rare inflammatory neutrophilic dermatosis manifesting as painful ulcers with violaceous, undermined borders on the lower extremities. It may occur in the context of classic syndromes like PAPA (pyogenic arthritis, pyoderma gangrenosum and acne) and SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis), as well as in a recently described entity named PASH (pyoderma gangrenosum, acne and suppurative hidradenitis). Pyoderma gangrenosum has recently been included within the spectrum of autoinflammatory diseases, which are characterized by recurrent episodes of sterile inflammation, without circulating autoantibodies and autoreactive T cells. In PAPA syndrome, different mutations involving the PSTPIP1 gene, via an increased binding affinity to pyrin, induce the assembly of inflammasomes. These are molecular platforms involved in the activation of caspase 1, a protease that cleaves inactive prointerleukin (pro-IL)-1ß to its active isoform IL-1ß. The overproduction of IL-1ß triggers the release of a number of proinflammatory cytokines and chemokines, which are responsible for the recruitment and activation of neutrophils, leading to neutrophil-mediated inflammation. In SAPHO syndrome, the activation of the PSTPIP2 inflammasome has been suggested to play a role in inducing the dysfunction of the innate immune system. Patients with PASH have recently been reported to present alterations of genes involved in well-known autoinflammatory diseases, such as PSTPIP1, MEFV, NOD2 and NLRP3. Pyoderma gangrenosum and its syndromic forms can be regarded as a single clinicopathological spectrum in the context of autoinflammation.

Detection of Low-Molecular-Weight Mast Cell-Activating Factors in Serum From Patients With Chronic Spontaneous Urticaria.

BACKGROUND AND OBJECTIVES: Functionally active autoantibodies to IgE and to the high-affinity IgE receptor (FcεRI) can be detected in serum in about 40% of patients with chronic spontaneous urticaria (CSU). Recent studies showed that serum from patients with CSU can induce activation of mast cells, irrespective of whether they carry high-affinity IgE receptors. To evaluate mast cell activation induced by factors in the serum of CSU patients with a molecular weight lower than that of autoantibodies. METHODS: Eight CSU patients and 5 healthy controls were evaluated. Whole serum and serum fractionated at 100, 50, and 30 kDa were used to stimulate in vitro LAD2 mast cells. The enzymatic activity of ß-hexosaminidase was evaluated in supernatants and cell pellets as a measure of mast cell degranulation. RESULTS: Mean (SEM) release of mast cell ß-hexosaminidase induced by whole serum from CSU patients was higher than that induced by serum from the healthy controls (14.4 [2.7%] vs 5.1 [2.4%]; P=.027). In addition, serum fractions below 100 kDa and below 50 kDa from CSU patients induced mast cell degranulation that was significantly higher than that induced by the corresponding fractions in sera from healthy controls (10.2% [1.4%] vs 3.8% [1.9%] [P=.024] and 10.1% [1.2%] vs 3.9% [1.7%] [P=.012], respectively). In 4 CSU patients, we evaluated serum fractions <30 kDa, which retained their capacity to activate mast cells (11.0% [0.7%]). CONCLUSIONS: This study shows that sera from CSU patients may contain low-molecular-weight mast cell-activating factors other than autoantibodies. These factors could be an additional mechanism contributing to the pathogenesis of CSU.

Eosinophil cationic protein levels parallel coagulation activation in the blister fluid of patients with bullous pemphigoid.

BACKGROUND: Bullous pemphigoid (BP) is an autoimmune blistering disease due to autoantibodies against two hemidesmosomal antigens, namely BP180 and BP230, and characterized by coagulation activation both at cutaneous and systemic levels. Skin-infiltrating eosinophils contribute to bulla formation and, upon activation, are supposed to initiate the coagulation cascade. OBJECTIVE: The aim of this study was to investigate whether the activation of eosinophils and coagulation are linked in BP. METHODS: We evaluated the correlation between eosinophil cationic protein (ECP) levels and concentrations of the prothrombotic markers F1 + 2 and D-dimer in blister fluid and blood samples of 30 BP patients. Thirty healthy subjects were used as normal controls. RESULTS: ECP, F1 + 2 and D-dimer plasma levels were significantly higher in BP patients than in normal subjects. A significant correlation was found between ECP plasma levels and blood eosinophil count (r = 0.54, P = 0.002). F1 + 2 plasma levels positively correlated with disease severity, expressed as the percentage of body surface area involved (r = 0.36, P = 0.048). A striking increase in ECP (288.8 ± 45.2 ng/mL), F1 + 2 (31 409.9 ± 2929.4 pmol/L) and D-dimer levels (342 798.3 ± 44 206 ng/mL) was found in blister fluid from BP patients. In blister fluid, ECP levels were significantly higher than in peripheral blood (P < 0.0001) and were positively correlated with the levels of both F1 + 2 (r = 0.4, P = 0.02) and D-dimer (r = 0.5, P = 0.0045). CONCLUSIONS: ECP levels are strikingly elevated in blister fluids from BP patients and correlate with markers of coagulation activation, supporting the view that eosinophils initiate the coagulation cascade at skin level.

Expression of cytokines, chemokines and other effector molecules in two prototypic autoinflammatory skin diseases, pyoderma gangrenosum and Sweet's syndrome.

Pyoderma gangrenosum (PG) and Sweet's syndrome (SS) are two inflammatory skin diseases presenting with painful ulcers and erythematous plaques, respectively; both disorders have a debilitating clinical behaviour and PG is potentially life-threatening. Recently, PG and SS have been included among the autoinflammatory diseases, which are characterized by recurrent episodes of sterile inflammation, without circulating autoantibodies and autoreactive T cells. However, an autoinflammatory pattern clearly supporting this inclusion has never been demonstrated. We studied 16 patients with PG, six with SS and six controls, evaluating, using a sandwich-based protein antibody array method, the expression profile of inflammatory effector molecules in PG, SS and normal skin. The expressions of interleukin (IL)-1 beta and its receptor I were significantly higher in PG (P = 0·0001 for both) and SS (P = 0·004-0·040) than in controls. In PG, chemokines such as IL-8 (P = 0·0001), chemokine (C-X-C motif) ligand (CXCL) 1/2/3 (P = 0·002), CXCL 16 (P = 0·003) and regulated upon activation normal T cell expressed and secreted (RANTES) (P = 0·005) were over-expressed. In SS, IL-8 (P = 0·018), CXCL 1/2/3 (P = 0·006) and CXCL 16 (P = 0·036) but not RANTES were over-expressed, suggesting that chemokine-mediated signals are lower than in PG. Fas/Fas ligand and CD40/CD40 ligand systems were over-expressed in PG (P = 0·0001 for Fas, P = 0·009 for Fas ligand, P = 0·012 for CD40, P = 0·0001 for CD40 ligand), contributing to tissue damage and inflammation, while their role seems to be less significant in SS. Over-expression of cytokines/chemokines and molecules amplifying the inflammatory network supports the view that PG and SS are autoinflammatory diseases. The differences in expression profile of inflammatory effectors between these two disorders may explain the stronger local aggressiveness in PG than SS.

High-molecular-weight kininogen cleavage correlates with disease states in the bradykinin-mediated angioedema due to hereditary C1-inhibitor deficiency.

BACKGROUND: The inherited deficiency of C1-inhibitor (C1-INH), which can be quantitative (type I) or qualitative (type II), is characterized by recurrent attacks of oedema, and it is known as hereditary angioedema due to C1-INH deficiency (HAE-C1-INH). The frequency of symptoms varies widely among patients and in the same patient during life. OBJECTIVE: To identify laboratory markers of disease severity in HAE-C1-INH patients. METHODS: We studied 162 patients with differently severe HAE-C1-INH during remission, 31 HAE-C1-INH patients during attacks, and 81 normal controls, evaluating complement parameters, spontaneous plasma kallikrein activity, the capacity of plasma to inhibit exogenous kallikrein activity, and cleavage of high-molecular-weight kininogen (HK). Sixty-five HAE-C1-INH patients were screened for mutations in the C1-INH gene. RESULTS: As expected, plasma C1-INH levels and activity and C4 levels were low in the HAE-C1-INH patients. Spontaneous plasma kallikrein activity in patients in remission was higher than in controls (P = 0.001) and increased during acute attacks (P = 0.01), whereas the capacity of inhibiting kallikrein activity was lower in patients in remission than in controls (P = 0.001) and further reduced during attacks (P = 0.001). HAE-C1-INH patients in remission had higher levels of cleaved HK than controls (P = 0.001), and these further increased during acute attacks (P = 0.001). Cleaved HK levels were higher in highly symptomatic HAE-C1-INH patients than in those with less frequent attacks (P = 0.001). Thirty-five different mutations in the C1-INH gene were equally distributed in patients with different attack frequencies. CONCLUSIONS: Measuring plasma levels of cleaved HK may be a sensitive mean of assessing disease severity in HAE-C1-INH patients.

Chronic urticaria and coagulation: pathophysiological and clinical aspects.

Chronic urticaria (CU) is a widespread skin disease, characterized by the recurrence of transient wheals and itch for more than 6 weeks. Besides autoimmune mechanisms, coagulation factors, in particular tissue factor and thrombin, might also participate in the disease pathophysiology. Tissue factor expressed by eosinophils can induce activation of blood coagulation generating thrombin which in turn can increase vascular permeability both directly, acting on endothelial cells, and indirectly, inducing degranulation of mast cells with release of histamine, as demonstrated in experimental models. D-dimer, a fibrin degradation product, generated following activation of the coagulation cascade and fibrinolysis, has been found to be increased during urticaria exacerbations; moreover, it has been proposed as a biomarker of severity and resistance to H1-antihistamines in CU patients. The possible role of coagulation in CU is also supported by case reports, case series and a small controlled study showing the efficacy of anticoagulant therapy in this disease. The purpose of this review was to summarize the available data on the possible contribution of coagulation to the pathophysiology of CU focusing on clinical aspects and possible future therapeutic developments.

Prothrombotic state and impaired fibrinolysis in bullous pemphigoid, the most frequent autoimmune blistering disease.

Bullous pemphigoid (BP) is a potentially life-threatening autoimmune blistering disease that is burdened with an increased risk of cardiovascular events. In BP, there is an interplay between inflammation and coagulation both locally, which contributes to skin damage, and systemically, which leads to a prothrombotic state. Fibrinolysis is an important defence mechanism against thrombosis, but has only been studied locally in BP and no systemic data are available. The aim of this observational study was to evaluate systemic fibrinolysis and coagulation activation in patients with BP. We measured parameters of fibrinolysis and coagulation by immunoenzymatic methods in plasma from 20 patients with BP in an active phase and during remission after corticosteroid treatment. The controls were 20 age- and sex-matched healthy subjects. Plasma levels of plasminogen activator inhibitor type 1 (PAI-1) antigen, PAI-1 activity and tissue plasminogen activator (t-PA) antigen were significantly higher in the BP patients with active disease than in healthy controls (P = 0·0001 for all), as were the plasma levels of the fibrin fragment d-dimer and prothrombin fragment F1+2 (P = 0·0001 for both). During remission after treatment, levels of PAI-1 antigen and PAI-1 activity decreased significantly (P = 0·008 and P = 0·006, respectively), and there was also a significant decrease in plasma levels of d-dimer (P = 0·0001) and F1+2 (P = 0·0001). Fibrinolysis is inhibited in patients with active BP, due mainly to an increase in plasma levels of PAI-1. Corticosteroids not only induce the regression of BP lesions, but also reduce the inhibition of fibrinolysis, which may contribute to decreasing thrombotic risk.

Diagnosis and disease severity assessment of epidermolysis bullosa acquisita by ELISA for anti-type VII collagen autoantibodies: an Italian multicentre study.

BACKGROUND: Epidermolysis bullosa acquisita (EBA) is a rare autoimmune mucocutaneous bullous disease caused by autoantibodies against type VII collagen, a component of anchoring fibrils that stabilizes dermoepidermal adherence. Type VII collagen is composed of a collagenous domain linked by the noncollagenous (NC)1 and NC2 domains. OBJECTIVES: To assess the repeatability, sensitivity and specificity of a recently developed enzyme-linked immunosorbent assay (ELISA) for detection of anti-type VII collagen autoantibodies, and to ascertain whether they may be a marker of disease activity in EBA. METHODS: Using this ELISA, which was able to recognize autoantibodies against the NC1 and NC2 epitopes of type VII collagen, we tested 14 EBA sera, 30 healthy control sera and 113 disease control sera. RESULTS: In the EBA sera group, 12 out of the 14 samples were positive in ELISA, with autoantibody titres varying from 7·2 to 127·9UmL(-1) (cutoff value <6), the sensitivity of the method being 86%. Among the controls, only two bullous pemphigoid sera tested positive, the specificity being 98·6%. A good correlation was found between EBA disease severity, expressed as autoimmune bullous skin disorder intensity score, and the serum levels of anti-collagen VII autoantibodies, measured by ELISA (n =14; r=0·965; P=0·0001). The intra- and interassay coefficients of variation of the ELISA method ranged from 6·3% to 18·3%. CONCLUSIONS: This NC1+NC2 ELISA can be a practical assay for the diagnosis of EBA. The correlation between autoantibody titres and disease severity suggests its usefulness as a marker of disease activity in EBA However, this should be confirmed by studies on larger series of patients.

Alterations of coagulation and fibrinolysis in patients with angioedema due to C1-inhibitor deficiency.

Patients with functional deficiency of C1-inhibitor (C1-INH) suffer from recurrent acute attacks (AA) of localized oedema associated with activation of the contact system, complement and fibrinolysis. To unravel further the role of coagulation and fibrinolysis in the pathophysiology of C1-INH deficiency, we performed simultaneous thrombin and plasmin generation measurements in plasma from patients with hereditary angioedema (HAE) due to C1-INH deficiency during AA (n = 23), in remission (R) (n = 20) and in controls (n = 20). During AA thrombin generation after in-vitro activation of plasma was higher than in controls, as demonstrated by shorter thrombin peak-time (P < 0·05), higher thrombin peak-height (P < 0·001) and increased area under the curve (AUC) (P < 0·05). Additionally, elevated levels of prothrombin fragment 1+2 (P < 0·0001) were observed in non-activated plasma from the same patients. In contrast, in activated plasma from patients during AA plasmin generation estimated as plasmin peak-height (P < 0·05) and plasmin potential (P < 0·05) was reduced, but non-activated plasma of the same patients showed elevated plasmin-anti-plasmin (PAP) complexes (P < 0·001). This apparent discrepancy can be reconciled by elevated soluble thrombomodulin (sTM) (P < 0·01) and thrombin activatable fibrinolysis inhibitor (TAFI) in patients during AA providing possible evidence for a regulatory effect on fibrinolysis. Plasminogen activator inhibitor-1 (PAI-1) was reduced in patients during AA indicating, together with the observed reduction of plasmin generation, the consumption of fibrinolytic factors. In conclusion, our results support the involvement of coagulation and fibrinolysis in the pathophysiology of HAE and show the possible application of simultaneous measurement of thrombin and plasmin generation to evaluate different clinical conditions in HAE patients.

Different rates of autoreactivity in patients with recurrent idiopathic angioedema associated or not with wheals.

BACKGROUND: The pathophysiology and triggers of idiopathic nonhistaminergic angioedema are unclear. This study aimed to assess autoreactivity in recurrent idiopathic angioedema associated or not with wheals. METHODS: The study population comprised 19 patients with recurrent idiopathic nonhistaminergic angioedema without wheals, 38 patients with angioedema and chronic urticaria (CU), and 52 patients with CU without angioedema. Twenty healthy individuals served as controls. Autoreactivity was evaluated in vivo using the autologous serum skin test (ASST) and in vitro by measuring serum-induced basophil histamine release (BHR). RESULTS: ASST results were negative in all patients with idiopathic angioedema without wheals and in healthy controls and positive in 29 of the 38 patients with angioedema and CU (76.3%) and in 26 of the 52 patients with CU without angioedema (50%) (P < .0001 for both CU groups). BHR was negative in the healthy controls and positive in 2 of the 19 patients with idiopathic angioedema without wheals (10.5%), in 18 of the 38 patients with angioedema and CU (47.3%) (P < .0001), and in 11 of the 52 patients with CU without angioedema (21.1%) (P < .03). CONCLUSION: The different rates of autoreactivity observed in patients with idiopathic nonhistaminergic angioedema without wheals and in patients with CU either with or without angioedema suggest that these disorders have a different pathophysiology. The failure to detect circulating vasoactive factors and histamine-releasing autoantibodies explains why H1 antihistamines are scarcely effective in most patients with idiopathic angioedema without wheals. However, they represent the cornerstone of CU treatment.

Serum eotaxin levels in patients with chronic spontaneous urticaria.

Eotaxin is a potent agonist for CC chemokine receptor 3 that can attract eosinophils at sites of inflammation. Given the potential role of eosinophils in chronic spontaneous urticaria (CU), we measured serum eotaxin levels together with C-reactive protein in 100 CU patients who were characterized according to autologous serum skin test (ASST) and disease severity. Serum eotaxin concentration was significantly higher in CU patients (median 140.1 pg/ml, range 33.7-718.7 pg/ml) than in 45 healthy controls (median 108.9 pg/ml, range 45.5-409.4 pg/ml) (p = 0.032) Serum eotaxin concentration was not significantly different in ASST-positive and ASST-negative patients as well as in patients with different urticaria activity scores. However, eotaxin levels tended to be higher in patients with intense symptoms. In the 7 patients observed during CU exacerbation and during remission, eotaxin serum levels tended to decrease during remission, although statistical significance was not reached (median concentration decreased from 170.0 pg/ml to 123.8 pg/ml). CRP levels were not significantly different in CU patients and healthy subjects, although there was a trend towards higher levels in the former population. Furthermore, in the 7 patients observed during CU exacerbation and during remission, CRP levels decreased significantly during remission (median concentration dropped from 4.1 microg/ml to 0.7 microg/ml, p = 0.015). No significant correlation was found between eotaxin and CRP serum levels. These findings indicate that serum eotaxin levels are increased in CU patients, although they do not reflect strictly disease activity. A role for eotaxin in eosinophil attraction and activation in CU can be envisaged.

Activation of coagulation in bullous pemphigoid and other eosinophil-related inflammatory skin diseases.

Bullous pemphigoid (BP) is a skin disease caused by autoantibodies to hemidesmosomal proteins BP180 and BP230, with eosinophils participating in blister formation. Tissue factor (TF), the initiator of coagulation, is embodied within the eosinophil granules and exposed upon activation. We evaluated the coagulation activation in patients with BP (63), chronic urticaria (CU; 20), atopic dermatitis (AD; 14), cutaneous drug reactions (CDRs; six), psoriasis (20), dermatitis herpetiformis (DH; four) and primary cutaneous T cell lymphoma (CTCL; five), and in 40 healthy controls. Prothrombin fragment F1+2 and d-dimer (coagulation markers) were measured by enzyme-linked immunosorbent assay (ELISA) in all plasma samples and BP blister fluid. Skin TF expression was evaluated immunohistochemically in the patients and 20 controls. F1+2 and d-dimer levels were higher in BP plasma than in control plasma (P = 0·0001 for both), and dramatically high in blister fluid; both correlated positively with disease severity, esinophil counts and anti-BP180 antibodies (P = 0·006-0·0001). Plasma F1+2 and d-dimer levels were higher in the CU, AD and CDR patients than in controls (P = 0·0001 for all), but normal in the psoriasis, DH and CTCL patients. Skin TF was expressed in the BP (P = 0·0001), CU (P = 0·0001), AD (P = 0·001) and CDR patients (P = 0·01), but not in the psoriasis, DH or CTCL patients. Co-localization confocal microscopy studies confirmed eosinophils as the source of TF in 10 BP patients. The coagulation cascade is activated in BP and other eosinophil-mediated skin disorders, but not in non-eosinophil driven conditions. This hypercoagulability may contribute to inflammation, tissue damage and, possibly, thrombotic risk.

Markers of autoreactivity, coagulation and angiogenesis in patients with nonallergic asthma.

BACKGROUND: Patients with nonallergic asthma frequently show autoreactivity as do subjects with chronic urticaria (CU). Activation of the coagulation cascade and hyper-expression of vascular endothelial growth factor (VEGF) were recently found in CU, and there is sparse evidence that the same may occur in asthma. OBJECTIVE: To investigate autoreactivity, activation of the coagulation cascade, and expression of VEGF in patients with nonallergic asthma. METHODS: Twenty-one adults with nonallergic asthma underwent autologous plasma skin test (APST) and the measurement of plasma levels of the prothrombin fragment F1+2, D-dimer, VEGF, and the inflammatory marker C-reactive protein (CRP). Twenty-one healthy sex- and age-matched subjects served as normal controls. RESULTS: The APST scored positive in 19 of 21 (90%) patients vs 0 controls. Mean fragment F1+2 plasma levels were significantly higher in patients with asthma (267 ± 243 pM) than in controls (150 ± 51 pM; P = 0.0001). Similarly, plasma levels of both D-dimer and VEGF were significantly higher in patients than in controls (D-dimer: 2364 ± 1467 vs 1301 ± 525 pM; P = 0.0001; VEGF: 1721 ± 2566 vs 76 ± 375 fM; P = 0.0001). A trend toward increased levels of F1+2, D-dimer, VEGF, and CRP was found in patients with a more severe disease according to GINA classification. CONCLUSION: Nonallergic asthma is characterized by autoreactivity as well as increased coagulation and angiogenesis markers, which are known to enhance vascular permeability. The presence of circulating vasoactive factors may be relevant to understand the disease pathophysiology and to detect novel therapeutic strategies in nonallergic asthma.

Mast cells are critically involved in serum-mediated vascular leakage in chronic urticaria beyond high-affinity IgE receptor stimulation.

BACKGROUND: Chronic urticaria (CU) is one of the most common skin disorders whose pathogenic mechanisms are not fully clarified. Autoimmune aetiology can be ascribed to 45% of patients with CU, and basophil histamine release is positive in 40% of cases. Our aim was to use a novel approach to evaluate the serum permeabilizing effect to identify the mediators of endothelial cell (EC) leakage and to define the role of mast cells (MCs) in the process. METHODS: Permeabilizing activity of sera from 19 patients with CU and 11 healthy blood donors was evaluated by measuring serum-induced degranulation of two MC lines, expressing (LAD2) or lacking (HMC-1) the IgE receptor. Mast cell supernatant (SN) was then incubated with an EC monolayer, and endothelial permeability was evaluated by Fluorescein isothiocyanate-bovine serum albumin leakage in a transwell system. RESULTS: All 19 patient sera failed to induce direct EC leakage, but 15/19 and 17/19 promoted degranulation of HMC-1 and LAD2, respectively. Interestingly, 85% of autologous serum skin test-negative sera were able to cause MC degranulation. Also, 17/19 SNs from HMC-1 and all SNs from LAD2 incubated with CU sera increased endothelial permeability. Endothelial cell leakage remained unchanged after Ig depletion and was prevented by antihistamine, platelet-activating factor or leukotriene antagonist. CONCLUSIONS: Our study shows that CU sera are able to degranulate MCs through an IgE- and IgG-independent mechanism. The nature of histamine-releasing factors involved is still unclear, but our finding opens new ways to the understanding of the pathogenesis of CU, particularly in patients not showing circulating autoantibodies to FcεRI or IgE.