Nóra Veszeli

“Nuts and Bolts” of Laboratory Evaluation of Angioedema

Angioedema, as a distinct disease entity, often becomes a clinical challenge for physicians, because it may cause a life-threatening condition, whereas prompt and accurate laboratory diagnostics may not be available. Although the bedside diagnosis needs to be established based on clinical symptoms and signs, family history, and the therapeutic response, later, laboratory tests are available. Currently, only for five out of the nine different types of angioedema can be diagnosed by laboratory testing, and these occur only in a minority of the patient population. Hereditary angioedema with C1-inhibitor (C1-INH) deficiency type I can be diagnosed by the low C1-INH function and concentration, whereas in type II, C1-INH function is low, but its concentration is normal or even elevated. C1q concentration is normal in both forms. Acquired angioedema with C1-INH deficiency type I is characterized by the low C1-INH function and concentration; however, C1q concentration is also low, and autoantibodies against C1-INH cannot be detected. Complement profile of acquired angioedema with C1-INH deficiency type II is similar to that of type I, but in this form, autoantibodies against C1-INH are present. Hereditary angioedema due to a mutation of the coagulation factor XII can be diagnosed exclusively by mutation analysis of FXII gene. Diagnostic metrics are not available for idiopathic histaminergic acquired angioedema, idiopathic non-histaminergic acquired angioedema, acquired angioedema related to angiotensin-converting enzyme inhibitor, and hereditary angioedema of unknown origin; these angioedemas can be diagnosed by medical and family history, clinical symptoms, and therapeutic response and by excluding the forms previously described. Several potential biomarkers of angioedema are used to date only in research. In the future, they could be utilized into the clinical practice to improve the differential diagnosis, therapy, as well as the prognosis of angioedema.

Comprehensive study into the activation of the plasma enzyme systems during attacks of hereditary angioedema due to C1-inhibitor deficiency

BackgroundThe activation of plasma enzyme systems contributes to hereditary angioedema attacks. We aimed to study the activation markers of the fibrinolytic, coagulation, and contact systems in a larger number of paired samples obtained from the same C1-INH-HAE patients in symptom-free periods and during attacks.MethodsEleven parameters (Factors XI, XII, and C1-inhibitor activity; the concentrations of the D-dimer, prothrombin fragments 1 + 2, plasminogen, plasminogen activator inhibitor-1 [PAI-1], thrombin-anti-thrombin III [TAT] complex, fibrinogen) were measured along with prothrombin time and activated partial thromboplastin time (aPTT), using commercial kits. We compared these markers in samples obtained from the same 39 patients during attack-free periods and during 62 edematous episodes. Forty healthy subjects of matching sex and age served as controls.ResultsCompared with the healthy controls, significantly higher FXI and FXII activity (p = 0.0007, p = 0.005), as well as D-dimer (p < 0.0001), prothrombin fragments 1 + 2 (p < 0.0001), and TAT (p = 0.0303) levels were ascertained in the patients during symptom-free periods. The evaluation of samples from symptom-free periods or obtained during attacks revealed the increase of FXII activity, as well as of the concentration of D-dimer, prothrombin fragments 1 + 2, and TAT during edematous episodes. PAI-1 level, prothrombin time, and aPTT decreased significantly during attacks, compared with symptom-free periods. D-dimer level was significantly higher during multiple- vs. single-site attacks.ConclusionsComparing a large number of paired samples from symptom-free periods or from edematous episodes allowed accurate appraisal of the changes occurring during attacks. Moreover, our study pointed out that individual episodes may be characterized by different marker patterns.

The role of the complement system in hereditary angioedema

Hereditary angioedema (HAE) is a rare, but potentially life-threatening disorder, characterized by acute, recurring, and self-limiting edematous episodes of the face, extremities, trunk, genitals, upper airways, or the gastrointestinal tract. HAE may be caused by the deficiency of C1-inhibitor (C1-INH-HAE) but another type of the disease, hereditary angioedema with normal C1-INH function (nC1-INH-HAE) was also described. The patient population is quite heterogeneous as regards the location, frequency, and severity of edematous attacks, presenting large intra- and inter-individual variation. Here, we review the role of the complement system in the pathomechanism of HAE and also present an overview on the complement parameters having an importance in the diagnosis or in predicting the severity of HAE.

Neutrophil activation during attacks in patients with hereditary angioedema due to C1-inhibitor deficiency.

BackgroundEarlier studies have shown that the absolute number of neutrophil granulocytes (NGs) may increase during attack of hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE). Whether NGs undergo activation during attack has not yet been investigated. However, as neutrophil elastase (NE) can cleave and inactivate C1-INH which may contribute to the dysregulation of the kallikrein-kinin system and hence, to edema formation. Our aim was to investigate the possible activation of NGs during attacks.MethodsWe studied blood samples obtained from 26 patients with C1-INH-HAE during symptom-free periods and during attacks, along with samples from 26 healthy volunteers. NG count (NGC), NE, myeloperoxidase (MPO), pentraxin 3 (PTX3), CRP, C5a, factor H, IL-8, and TNF-α levels were measured.ResultsNGC was higher during attacks than during symptom-free periods (p = 0.0132), and the same was observed for NE (p = 0.0026), MPO (p = 0.0008), and PTX3 levels (p = 0.0409). There was a strong positive correlation between NE and MPO levels during attacks (p < 0.0001, R = 0.709). Furthermore, IL-8 (p = 0.0061) and TNF-α (p = 0.0186) levels were also elevated during attacks, compared with symptom-free periods. By contrast, C5a and factor H levels were similar in samples obtained during attacks or in symptom-free periods.ConclusionIncreased NGC was associated with elevated NE and MPO levels – this suggests neutrophil activation during attacks. The strong positive correlation between NE and MPO levels, together with the elevated PTX3 concentration, may indicate the expression of neutrophil extracellular traps. All these processes may contribute to the activation of kallikrein-kinin system, which leads to the onset of an edematous episode.

A systematic analysis of the complement pathways in patients with neuromyelitis optica indicates alteration but no activation during remission

Neuromyelitis optica (NMO) is an autoimmune demyelinating inflammatory disorder, mediated by pathogenic autoantibodies against aquaporin 4 (AQP4), the main water channel of the central nervous system (CNS). NMO is characterized by local IgG deposition and complement activation within the CNS, but the three complement pathways have not been systematically investigated. We evaluated the overall activation of the classical, alternative, and MBL-lectin pathways in the peripheral blood of 25 patients with AQP4-seropositive NMO spectrum during remission and 113 healthy controls by three ways: (1) we measured the concentrations of native complement proteins of the three pathways [C1-inhibitor (C1-inh), C1q, C4, C3, C5, factor I, factor B, properdin]; (2) the concentrations of complement products suggesting in vivo activation (C1rC1sC1-inh, C3a, C3bBbP, and SC5b-9); and (3) the total activity of the three complement pathways. Additionally we measured levels of C1rC1sC1-inh, C3a, C3bBbP in cerebrospinal fluid (CSF) of 6 patients with relapsing NMO and of 18 patients with relapsing multiple sclerosis (MS). The serological studies indicated that total complement activity of the classical [median (interquartile range) 72 (61-82) vs. 65 (56-73) CH50/mL; p=0.0122] and of the lectin pathways [73 (59-111) vs. 49 (3-92)%; p=0.0078)] were elevated compared with the controls, whereas that of the alternative pathway was not significantly different. The levels of C3 [1.1 (0.9-1.3) vs. 1.4 (1.2-1.5)g/L; p<0.0001], factor B [89 (77-115) vs. 103 (93-113)%; p=0.0397] and factor I [85 (69-95) vs. 101 (93-107)%; p=0.0007], as well as of properdin [92 (74-104) vs. 108 (97-122)%; p=0.0028] were significantly lower in the patients than in the controls. The only increase in the patients was ascertained in the relative concentration of C1rC1sC1-inh vs. the C1-inhibitor (42.3 [31.9-65.0] vs. 30.8 [13.5-43.5] AU/mg; p=0.0007). The absolute and relative levels of the other complement activation products were not elevated in the patients. On the contrary, the serum concentrations of C3a, C3bBbP, and SC5b-9 of the patients were lower than those of the controls. The absolute concentration of the complement activation products (C1rC1sC1-inh, C3bBbP, C3a) and the ratio of C3bBbP/C1rC1sC1-inh did not differ in NMO and MS CSF samples. The ratio of C3bBbP/C1rC1sC1-inh was similar in NMO plasma and CSF samples. We found a higher ratio of C3bBbP/C1rC1sC1-inh in the plasma of control subjects compared to those in any pathological samples. Our results do not indicate substantial systemic complement activation if NMO activity is adequately controlled; nevertheless, the complement system is abnormally affected even during remission. The relative ancillarity of the alternative compared to the classical pathway may also suggest that suppression of the alternative pathway by treatment may be important to achieve remission.

First report of icatibant treatment in a pregnant patient with hereditary angioedema

Hereditary angioedema resulting from C1‐inhibitor deficiency (C1‐INH‐HAE) is a rare, autosomal dominant disorder, characterized by recurrent attacks of edema formation. The management of pregnant patients with C1‐INH‐HAE is often a challenge for the physician. There is limited experience with novel therapies. Plasma‐derived nanofiltered C1‐INH (pnfC1‐INH) is the only recommended therapeutic option during pregnancy. In our 26‐year‐old female patient with type II C1‐INH‐HAE, pregnancy was confirmed in the sixth week of gestation. During this period, the patient received the bradykinin B2‐receptor antagonist, icatibant, on five occasions, as acute treatment. She experienced 119 attacks, for which she received 108 vials of pnfC1‐INH during her pregnancy. The patient gave birth to a healthy baby. No side effects were detected with either treatment. No reports have been published to date on multiple dosing with icatibant during the first trimester of pregnancy. This therapy proved effective and free of maternal or fetal adverse effects.

The relationship between anxiety and quality of life in children with hereditary angioedema

The severe life‐threatening characteristics of hereditary angioedema (HAE) with C1‐inhibitor deficiency (C1‐INH‐HAE) can affect anxiety levels among pediatric patients. This emotional burden together with the physical restrictions of C1‐INH‐HAE may decrease childrens health‐related quality of life (HRQoL).

Health-related quality of life among children with hereditary angioedema

The clinical expressions of hereditary angioedema with C1‐inhibitor deficiency (C1‐INH‐HAE) and its related burden may negatively affect patient quality of life. This study aimed to assess health‐related quality of life (HRQoL) in children with C1‐INH‐HAE.

Risk of thromboembolism in patients with hereditary angioedema treated with plasma-derived C1-inhibitor.

BACKGROUND Plasma-derived C1-inhibitor (C1-INH) concentrates (pdC1-INH) have been used as safe and effective treatments for hereditary angioedema with C1-INH deficiency (C1-INH-HAE) for >30 years. Notwithstanding this, sporadic reports and a study into the high-dose therapy of neonates with C1-INH concentrate administered in an off-label indication raised concerns that this drug might increase the risk of thromboembolism. OBJECTIVE To investigate the incidence of thromboembolism and the background of the risk factors related to treatment with pdC1-INH. METHODS Our retrospective cohort study of 144 patients with C1-INH-HAE compared the incidence of thromboembolism and its risk factors in patients who received pdC1-INH with those who did not receive pdC1-INH as well as with those treated with danazol or with tranexamic acid. RESULTS During the observation period (29 years), 104 of the 144 subjects received pdC1-INH. The average dose per treatment was 573.59 IU. None of the patients used an indwelling central venous catheter. Multiple risk factors for thromboembolism were identified in 93 of the 104 patients treated with pdC1-INH. The incidence rate of thromboembolism was 0.0019/100 person-years in patients treated with pdC1-INH, whereas it was 0.0211/100 person-years in the not-treated group. CONCLUSION Our cohort study did not find any evidence for an increased risk of thromboembolism during treatment with pdC1-INH, despite the presence of multiple predisposing factors.

Home treatment of attacks with conestat alfa in hereditary angioedema due to C1-inhibitor deficiency.

Conestat alfa, a recombinant human C1 inhibitor (rhC1-INH) is a novel therapeutic option for the acute treatment of hereditary angioedema due to C1-INH (HAE-C1-INH) deficiency. Our aim was to investigate the efficacy and safety profile of conestat alfa in patients with HAE-C1-INH, under real-life conditions. We analyzed 65 edematous episodes requiring acute treatment and occurring in two female HAE-C1-INH patients. The patients were treated at home with rhC1-INH per occasion. They recorded the time of rhC1-INH administration, the time to the onset of improvement, and time to the complete resolution of symptoms, as well as the side effects. Symptom severity and patient satisfaction were measured with a visual analog scale (VAS). Thirty-three HAE attacks occurred in submucosal tissue, 17 in subcutaneous tissue, and 15 had mixed locations. After the administration of rhC1-INH, clinical symptoms improved within 0.50 (0.17-4.50 hours) hours and resolved completely within 9.00 (1.67-58.75 hours) hours. The time between the onset of the attack and the administration of rhC1-INH was correlated with the time when the symptoms stopped worsening (R = 0.3212; p = 0.0096) and the time to complete resolution of the symptoms (R = 0.4774; p < 0.0001). The time to response to the drug differed with attack location. The efficacy and safety of rhC1-INH persisted after repeated use. None of the patients experienced a recurrence of the HAE attack or drug-related systemic adverse events. The mean VAS score of patient satisfaction was 93.14. Home treatment with rhC1-INH was an effective and well-tolerated therapy for all types of HAE attacks.