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Povzetek: Background: An elevated basal serum tryptase level is associated with severe systemic anaphylaxis, most notably caused by Hymenoptera envenomation. Although clonal mast cell disease is the culprit in some individuals, it does not fully explain this clinical association. Objective: Our aim was to determine the prevalence and associated impact of tryptase genotypes on anaphylaxis in humans. Methods: Cohorts with systemic mastocytosis (SM) and venom as well as idiopathic anaphylaxis from referral centers in Italy, Slovenia, and the United States, underwent tryptase genotyping by droplet digital PCR. Associated anaphylaxis severity (Mueller scale) was subsequently examined. Healthy volunteers and controls with nonatopic disease were recruited and tryptase was genotyped by droplet digital PCR and in silico analysis of genome sequence, respectively. The effects of pooled and recombinant human tryptases, protease activated receptor 2 agonist and antagonist peptides, and a tryptase-neutralizing mAb on human umbilical vein endothelial cell permeability were assayed using a Transwell system. Results: Hereditary [alpha]-tryptasemia (H[alpha]T)--a genetic trait caused by increased [alpha]-tryptase-encoding Tryptase-[alpha]/[beta]1 (TPSAB1) copy number resulting in elevated BST level--was common in healthy individuals (5.6% [n = 7 of 125]) and controls with nonatopic disease (5.3% [n = 21 of 398]). H[alpha]T was associated with grade IV venom anaphylaxis (relative risk = 2.0; P < .05) and more prevalent in both idiopathic anaphylaxis (n = 8 of 47; [17%; P = .006]) and SM (n = 10 of 82 [12.2%; P = .03]) relative to the controls. Among patients with SM, concomitant H[alpha]T was associated with increased risk for systemic anaphylaxis (relative risk = 9.5; P = .007). In vitro, protease-activated receptor-2-dependent vascular permeability was induced by pooled mature tryptases but not [alpha]- or [beta]-tryptase homotetramers. Conclusions: Risk for severe anaphylaxis in humans is associated with inherited differences in [alpha]-tryptase-encoding copies at TPSAB1.
Ključne besede: mastocytosis, venoms, hypersensitivity, anaphylaxis - diagnosis, mast cells, idiopathic anaphylaxis, mast cell activation, hereditary alpha-tryptasemia
DiRROS - Objavljeno: 11.09.2020; Ogledov: 482; Prenosov: 68

Povzetek: Objective: Hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE) is a rare disease, characterized by swellings. We aimed to characterize on a clinical and molecular basis C1-INH-HAE patients in the Republic of Macedonia. Results: All 15 patients from six unrelated families were diagnosed with C1-INHHAE type I, with a mean age of symptom onset of 11 years and an average delay of diagnosis of 7 years. Patients reported on average 31 angioedema attacks/year, with a median clinical severity score (CSS) of 7. We identified three known mutations, and two mutations (c.813_818delCAACAA and c.1488T>G) were reported for the first time. To address the genotype-phenotype association, a pooled analysis including 78 C1-INH-HAE south-eastern European patients was performed, with additional analysis of F12-46C/T and KLKB1- 428G/A polymorphisms. We demonstrated that patients with nonsense and frameshift mutations, large deletions/insertions, splicing defects, and mutations at Arg444 exhibited an increased CSS compared with missense mutations, excluding mutations at Arg444. In addition, the CC F12-46C/T polymorphism was suggestive of earlier disease onset. Discussion: Genetic analysis helped identify the molecular basis of C1-INH-HAE given that causative mutations in SERPING1 were detected in all patients, including an infant before the appearance of clinical symptoms. We identified two novel mutations and further corroborated the genotype-phenotype relationship, wherein mutations with a clear effect on C1-INH function predispose patients to a more severe disease phenotype and CC F12-46C/T predisposes patients to earlier disease onset.
Ključne besede: hereditary angioedemas -- genetics -- Macedonia, C1 inhibitor, SERPING1 gene, C1 inhibitor, SERPING1 gene
DiRROS - Objavljeno: 30.11.2020; Ogledov: 242; Prenosov: 50

Povzetek: Hereditary angioedema (HAE) is a rare autosomal dominant disease with deficiency (type I) or dysfunction (type II) of C1 inhibitor, caused by mutations in the C1-INH gene, characterized by recurrent submucosal or subcutaneous edemas including skin swelling, abdominal pain and life-threatening episodes of upper airway obstruction. The aim of this study was to investigate healthcare experiences in children with HAE due to C1 inhibitor deficiency (C1-INH-HAE) in Croatia in order to estimate the number of affected children and to recommend management protocols for diagnosis, short-term prophylaxis and acute treatment. Patients were recruited during a 4-year period at five hospitals in Croatia. Complement testing was performed in patients with a positive family history. This pilot study revealed nine pediatric patients positive for C1-INH- HAE type I, aged 1-16 years, four of them asymptomatic. Before the age of one year, C1-INH levels may be lower than in adults; it is advisable to confirm C1-INH-HAE after the age of one year. Plasma-derived C1- INH is recommended as acute and short-term prophylactic treatment. Recombinant C1-INH and icatibant are licensed for the acute treatment of pediatric patients. In Croatia, HAE is still underdiagnosed in pediatric population.
Ključne besede: hereditary angioedemas -- genetics -- Croatia, inborn genetic diseases -- Croatia, pediatrics -- Croatia, C1 inhibitor, SERPING1 gene, children
DiRROS - Objavljeno: 16.12.2020; Ogledov: 267; Prenosov: 206
Celotno besedilo (477,81 KB)

Povzetek: Background: The role of chemokines in anaphylaxis is unclear. Methods: We prospectively recruited 49 patients presenting to the emergency department with an acute episode of anaphylaxis and 28 healthy subjects. We measured serum levels of the chemokines CCL2, CCL5, CCL7, CCL8, CCL11, CCL13, CCL17, CCL21, CCL22, CCL24, and CCL26, tryptase, the absolute number of circulating basophils, monocytes, lymphocytes, and PMNs, and whole blood FCER1A, CPA3 and HDC gene expression at two time points: during the anaphylactic episode and in convalescent samples collected approximately 3 months later. We then investigated the in vitro chemotactic activity of chemokines induced during anaphylaxis for the in vitro migration of the corresponding cells. Results: Only CCL2 chemokine levels were signifcantly increased in anaphylaxis samples (median 514 pg/ml) compared to convalescent samples (284 pg/ml, P<0.0001) and healthy subjects (279 pg/ml, P<0.0001); there was no signifcant diference in any of the other chemokines. There was a signifcant positive correlation between the rates of increase of serum CCL2 (median [range]: 106.0% [-44.7% to 557.4%]) and tryptase (133.8% [-6.6% to 893.4%]; r=0.68, P<0.0001) and between the acute concentration of serum CCL2 and the acute concentration of serum tryptase (r=0.77, P<0.0001). The number of circulating basophils, but not other blood cells, signifcantly decreased during anaphylaxis (median 5.0 vs. 19.1 cells/[micro]l in convalescent samples; P<0.0001); a decrease in whole-blood gene expression of basophil markers (PKljučne besede: anaphylaxis, chemokines, tryptases, basophils, chemotaxis, CCL2, cell migration
DiRROS - Objavljeno: 18.01.2021; Ogledov: 227; Prenosov: 124
Celotno besedilo (2,04 MB)

Povzetek: Background. Clonal mast cell disorders and elevated BST of unknown cause(s) are associated with severe Hymenoptera venom-triggered anaphylaxis (HVA). However, some individuals with clonal disease have normal BST (<11.4 ng/mL). Objective. To evaluate whether screening for KIT p.D816V in the blood is a useful clinical tool to risk-stratify patients with venom allergy. Methods. We prospectively recruited 374 patients with Hymenoptera allergy and no overt signs of mastocytosis referred to our center in the years 2018-19. KIT p.D816V was determined in the peripheral blood with qPCR and tryptase genotyping was performed by droplet-digital PCR. Results. 351 patients (93.9%) had normal levels of BST and KIT p.D816V was detected in 8% of patients (28/351), predominantly in patients with the most severe Mueller grade IV anaphylaxis (18.2%[24/132] vs 1.8%[4/88 in grade III; 0/131 in other grades] in lower grades; P<0.001). In grade IV patients with normal BST, KIT p.D816V was associated with more severe symptoms including a significantly higher frequency of loss of consciousness (58.3%[14/24] vs 34.3%[37/108]; P=0.03) and absence of skin symptoms (41.7%[10/24] vs 15.7%[17/108]; P=0.004). Among patients with normal BST, KIT p.D816V (OR [95%CI]: 10.25[3.75-36.14]; P<0.0001) was the major risk factor associated with severe HVA. Hereditary [alpha]-tryptasemia (H[alpha]T), due to increased germline copies of TPSAB1 encoding [alpha]-tryptase was the most common cause (65.2%; 15/23) of elevated BST in patients with HVA and together with KIT p.D816V accounted for 90% (20/23) of BST elevations in HVA patients. Conclusion. These results indicate that routine KIT p.D816V screening identifies clonal disease in high-risk HVA patients regularly missed using BST alone.
Ključne besede: anaphylaxis, venoms, hypersensitivity, hereditary alpha-tryptasemia
DiRROS - Objavljeno: 31.03.2021; Ogledov: 95; Prenosov: 41