C1 Inhibitor Research Articles

Prolonging the circulatory half-life of C1 esterase inhibitor via albumin fusion.

Hereditary Angioedema (HAE) is an autosomal dominant disease characterized by episodic swelling, arising from genetic deficiency in C1-esterase inhibitor (C1INH), a regulator of several proteases including activated Plasma kallikrein (Pka). Many existing C1INH treatments exhibit short circulatory half-lives, precluding prophylactic use. Hexahistidine-tagged truncated C1INH (trC1INH lacking residues 1-97) with Mutated N-linked Glycosylation Sites N216Q/N231Q/N330Q (H6-trC1INH(MGS)), its murine serum albumin (MSA) fusion variant (H6-trC1INH(MGS)-MSA), and H6-MSA were expressed in Pichia pastoris and purified via nickel-chelate chromatography. Following intravenous injection in mice, the mean terminal half-life of H6-trC1INH(MGS)-MSA was significantly increased versus that of H6-trC1INH(MGS), by 3-fold, while remaining ~35% less than that of H6-MSA. The extended half-life was achieved with minimal, but significant, reduction in the mean second order rate constant of Pka inhibition of H6-trC1INH(MGS)-MSA by 33% relative to that of H6-trC1INH(MGS). Our results validate albumin fusion as a viable strategy for half-life extension of a natural inhibitor and suggest that H6-trC1INH(MGS)-MSA is worthy of investigation in a murine model of HAE.

Rare connective tissue diseases in patients with C1-inhibitor deficiency hereditary angioedema: first evidence on prevalence and distribution from a large Italian cohort study

IntroductionIn patients with Hereditary Angioedema (HAE) related to primary C1 inhibitor deficiency (C1INH), the defective clearance of immune complexes and apoptotic materials along with impairment of normal humoral response potentially leads to autoimmunity. Few studies report evidence on autoimmune diseases in C1INH-HAE, but no large population studies focus on rare connective tissue diseases (RCTDs). We aim at evaluating for the first time prevalence and distribution of RCTDs - Systemic Lupus Erytematosus (SLE), primary Sjogren Syndrome (SjS), primary antiphospholipid syndrome (APS), Systemic Sclerosis (SSc), and mixed connective tissue diseases (MCTD) in a large Italian cohort of C1INH-HAE patients.MethodsA multicenter observational study includes C1INH-HAE patients from ITACA Centers throughout Italy (time frame Sept 2023-March 2024). Inclusion criteria are i. a defined diagnosis of type I or type II C1INH-HAE; ii. age ≥15 years (puberty already occurred); iii. enrollment in the ITACA Registry. The diagnosis of SLE, primary SjS, primary APS, SSc, and MCTD are made in accordance with international classification criteria.ResultsData are collected from a total of 855 C1INH-HAE patients referring to 15 ITACA Centers. Patients with concomitant RCTDs were 18/855 (2.1%) with F:M ratio 3.5 and a prevalent type I C1INH-HAE diagnosis (87.2%). A diagnosis of SLE results in 44.5% of cases (n=8) while the remaining diagnoses are primary SjS (22.2%, n=4), primary APS (16.6%, n=3), SSc (11.2%, n=2), and a single case of MCTD (5.5%). The female gender is prevalent in all the RCTDs. Patients on long term prophylaxis (LTP) are significantly prevalent in RCTDs group than in the whole C1INH-HAE population (p<0.01).ConclusionsA relevant prevalence of RCTDs is documented in C1INH-HAE patients, mainly SLE. Patients with RCTDs are on LTP in a significant proportion supporting the idea of a bidirectional link between C1INH-HAE and autoimmunity.

Hereditary Angioedema and Venous Thromboembolism: Where There's Smoke, There's Fire.

C1-inhibitor deficiency-associated hereditary angioedema (C1INH-HAE) is a rare congenital swelling disorder caused by mutations in the SERPING1 gene. Despite evidence of a systemic procoagulant state in C1INH-HAE, dogma held that this disorder was not associated with thrombotic pathologies. Recent population scale epidemiological evidence has directly challenged this, with C1INH-HAE being associated with a significantly increased risk of venous thromboembolism (VTE). This review considers the growing body of evidence supporting associations between HAE and both a systemic procoagulant state and an increased risk of VTE. In the setting of C1INH-HAE, the relationship between the observed procoagulant and thrombotic phenotypes is a prime example of "where there's smoke, there's fire." This review also discusses the impact of C1INH-HAE disease modifying therapies on coagulation and VTE. Further, the utility of preclinical mouse models of C1-inhibitor deficiency is considered.

Unveiling the Complexities of Hereditary Angioedema

Hereditary angioedema (HAE) is a rare and potentially life-threatening genetic disorder, constituting approximately 2% of all clinical cases of angioedema, with a global prevalence estimated between 1 in 50,000 and 1 in 150,000 individuals. The condition affects individuals of all genders and ethnic backgrounds without significant variation. HAE is classified into three types. Type I HAE, which accounts for 85% of cases, is characterized by a deficiency of the C1 esterase inhibitor (C1-INH) gene. Type II HAE, making up 15% of cases, involves a dysfunctional C1-INH. Type III HAE, which represents about 5% to 10% of cases, is often estrogen-dependent and although several mutations have been identified, it typically involves normal C1-INH activity. Despite the differences in C1-INH functionality, all three types of HAE manifest with similar clinical symptoms. HAE leads to recurrent episodes of non-pruritic angioedema, which occurs in the absence of urticaria. Breakthroughs in understanding HAE pathophysiology have revolutionized treatment, leading to the development of highly targeted therapies for both acute management and long-term prevention. Meanwhile, cutting-edge advancements in omics technologies are unlocking new possibilities for biomarker discovery, paving the way for more precise diagnoses and personalized treatment strategies that could significantly enhance patient outcomes. This review will delve into the intricate pathophysiology, diverse clinical presentations, and diagnostic challenges of HAE while exploring emerging biomarkers and innovative approaches to therapeutic management and prevention strategies. Additionally, it will underscore the vital importance of screening family members of affected individuals, even when symptoms are not present.

Berotralstat for hereditary angioedema with C1 inhibitor deficiency: a practical guide for clinicians.

Berotralstat for hereditary angioedema with C1 inhibitor deficiency: a practical guide for clinicians.

Long-term safety and efficacy of garadacimab for preventing hereditary angioedema attacks: Phase 3 open-label extension study.

Hereditary angioedema (HAE) is a chronic, unpredictable disease. Long-term prophylactic treatments that offer durable efficacy, safety, and convenience are required to assist patients in achieving complete disease control, per international guidelines. We report an interim analysis of an ongoing phase 3 (VANGUARD) open-label extension (OLE) study evaluating the long-term safety and efficacy of garadacimab for HAE prophylaxis. Adults and adolescents aged ≥12 years with HAE previously participating in phase 2 and pivotal phase 3 (VANGUARD) studies were rolled over to an OLE, alongside newly enrolled patients. Patients received garadacimab 200 mg subcutaneously, once monthly for ≥12 months. The primary endpoint was treatment-emergent adverse events (TEAEs) in patients with C1 inhibitor deficiency/dysfunction. At data cut-off (February 13, 2023; N = 161), median (interquartile range) exposure was 13.8 months (11.9-16.3). For the primary endpoint, 133/159 patients experienced ≥1 TEAE (524 events), equivalent to 0.23 events/administration and 2.84 events/patient-year. Garadacimab-related TEAEs (13% of patients, 52 events) were most commonly injection-site reactions (ISRs). No deaths occurred. One patient discontinued treatment due to garadacimab-related moderate ISR. Most TEAEs were mild/moderate; three events were serious (COVID-19, two events; abdominal HAE attack, one event) and not garadacimab related. No abnormal bleeding, thromboembolic, severe hypersensitivity, or anaphylactic events were observed. Mean HAE attack rate decreased by 95% from the run-in period; 60% of patients were attack-free. Almost all patients (93%) rated their response to garadacimab as "good" or "excellent." Garadacimab has a favorable safety profile suitable for long-term use and provides durable protection against HAE attacks.

Initial Experience of Long-Term Prophylaxis with Lanadelumab for Hereditary Angioedema in China: A Clinical Observation Study on Six Patients

Plain Language SummaryHereditary angioedema (HAE) is a rare genetic disease characterized by recurring episodes of painful swelling of the subcutaneous and submucosal tissue, and its pathogenesis is due to the deficiency or dysfunction C1-esterase inhibitors. HAE attacks can affect many areas of the body, but most frequently involve the extremities, gastrointestinal tract, genitals, face, and upper airway. Swelling of the larynx can occur, with potentially fatal consequences owing to asphyxiation. Since 2020, China has had the only first-line treatment drug that can prevent HAE attacks – lanadelumab. Our study evaluated the efficacy and safety of lanadelumab by observing the 6 patients in China mainland who were the first to use it. Our research showed that lanadelumab can prevent the attack of HAE, greatly improve the quality of life of patients, and has good safety. A reasonable dosage plan can ensure stable therapeutic effects of lanadelumab. In addition, the efficacy of lanadelumab remained stable during COVID-19 vaccination and infection.

C1 esterase inhibitor (C1-INH) for the off-label treatment of angiotensin-converting enzyme inhibitor induced angioedema

Introduction: Currently, C1 esterase inhibitor (C1-INH) is indicated for hereditary angioedema (HAE) but is utilized off-label for angiotensin- converting enzyme inhibitors (ACEi) induced angioedema (AAE). There is no standard of care for the treatment of AAE, however patients may receive a combination of epinephrine, corticosteroids, fresh frozen plasma (FFP), tranexamic acid (TXA), and histamine 1 and 2 receptor antagonists (H1RA, H2RA). C1-INH place is therapy is not well defined. Materials & Methods: A retrospective chart review was conducted from patients at a large academic medical center who received C1-INH for AAE between January 2012 and May 2022. Variables and outcomes of interest were receipt of alternative angioedema treatment prior to C1-INH, time of C1-INH administration, dose of C1-INH, need for intubation or surgical airway placement, duration of intubation, and hospital length of stay. Results: All patients received additional medications for angioedema prior to C1-INH administration. Steroids and H1RAs were most common. The dose of C1-INH ranged from 11.7 IU/kg to 23.2 IU/kg with an average dose of 19.3 IU/kg. Five patients required airway support with four requiring intubation (30.8%) and one requiring a surgical airway. Conclusions: This retrospective review of 13 patients showed mixed results for C1-INH to prevent intubation in AAE. Providers should consider limiting the use of C1-INH to patients who remain symptomatic after administering a combination of other therapies when there is an ongoing risk for airway compromise and adequate time for preparation, administration, and effect.

A novel assay of excess plasma kallikrein-kinin system activation in hereditary angioedema.

Cleaved high-molecular-weight kininogen (HKa) is a disease state biomarker of kallikrein-kinin system (KKS) activation in patients with hereditary angioedema due to C1 inhibitor deficiency (HAE-C1INH), the endogenous inhibitor of plasma kallikrein (PKa). Develop an HKa-specific enzyme-linked immunosorbent assay (ELISA) to monitor KKS activation in the plasma of HAE-C1INH patients. A novel HKa-specific antibody was discovered by antibody phage display and used as a capture reagent to develop an HKa-specific ELISA. Specific HKa detection following KKS activation was observed in plasma from healthy controls but not in prekallikrein-, high-molecular-weight kininogen-, or coagulation factor XII (FXII)-deficient plasma. HKa levels in plasma collected from HAE-C1INH patients in a disease quiescent state were higher than in plasma from healthy controls and increased further in HAE-C1INH plasma collected during an angioedema attack. The specificity of the assay for PKa-mediated HKa generation in minimally diluted plasma activated with exogenous FXIIa was demonstrated using a specific monoclonal antibody inhibitor (lanadelumab, IC50 = 0.044 µM). An ELISA was developed for the specific and quantitative detection of HKa in human plasma to support HAE-C1INH drug development. Improved quantification of the HKa biomarker may facilitate further pathophysiologic insight into HAE-C1INH and other diseases mediated by a dysregulated KKS and may enable the design of highly potent inhibitors targeting this pathway.

Uncovering a novel SERPING1 pathogenic variant: insights into the aggregation of C1-INH in hereditary angioedema

BackgroundHereditary angioedema (HAE) is a rare autosomal dominant genetic disease characterized by recurrent edema and a potentially fatal risk. Despite its severity, there is a notable lack of effective methods for predicting and preventing HAE attacks. This study aims to thoroughly investigate the underlying pathological mechanisms of HAE and identify potential biomarkers that could aid in its prediction and prevention.ResultsIn our investigation, we have discovered a novel pathogenic variant of the SERPING1 gene, specifically c.708T > G, in a Han family affected by HAE. Our observations indicate that this variant leads to an increase in the accumulation of C1-INH within the endoplasmic reticulum (ER), resulting in the upregulation of GRP75 protein expression. This cascade of events resulted in Ca2+ overload, disruption of mitochondrial structure and function, and eventually triggered apoptosis. Using siRNA to knock down GRP75 mitigates cellular calcium overload and mitochondrial damage induced by the SERPING1 mutation.ConclusionBased on our findings, we propose that the detection of intracellular Ca2+ concentration could serve as a valuable biomarker for predicting acute attacks of HAE in patients. This discovery holds significant implications for the development of more targeted and effective strategies in the management of HAE.

Hereditary Angioedema in Pregnancy: A Case Report and Review of Obstetric Anesthesia Management.

Hereditary angioedema (HAE) is a rare disorder due to C1 esterase inhibitor deficiency, causing recurrent swelling. Pregnancy can exacerbate HAE due to estrogen fluctuations alongside peripartum stress and trauma. We present a pregnant patient with HAE who underwent induction of labor and vaginal delivery with neuraxial anesthesia. Management included C1-inhibitor prophylaxis, 48 hours of postpartum monitoring, and a self-treatment plan at discharge. Angioedema prevention involves timely anesthesia consultation, accessible emergency airway equipment, early neuraxial anesthesia, planned vaginal delivery, and 48 to 72 hours of close postpartum monitoring. Readily available C1-inhibitor and a multidisciplinary approach with these recommendations are crucial for peripartum management.

Elevated C1s/C1-INH in serum and plasma of myasthenia gravis patients

Myasthenia Gravis (MG) is an autoimmune neuromuscular disorder where acetylcholine receptor (AChR) antibodies induce membrane attack complex formation at the muscle membrane. The C1-inhibitor (C1-INH) regulates the classical pathway and is a promising marker in other autoimmune disorders. Treatment options for AChR antibody MG include complement inhibitors; nevertheless, the early pathway activation in MG remains unclear. Serum and plasma C1s-C1-INH levels were higher in MG patients than in matched healthy controls, supporting early classical pathway activation in most MG patients. These findings allow prospective validation studies of activated C1s as a putative treatment target and potential accompanying biomarker in MG.

Two pediatric hereditary angioedemathe families: case report and literature review

Objective: To summarize the clinical characteristics of two families with hereditary angioedema in children. Methods: A retrospective analysis was conducted on the general information, clinical manifestations, genetic variations, and laboratory test results of two families diagnosed with hereditary angioedema at Department of Rheumatology and Immunology, Shenzhen Children's Hospital from December 2022 to May 2023. And using keywords such as "children" "adolescent" "infant" "toddler" "pediatric" "hereditary angioedema" search for relevant literature from VIP, Wanfang, CNKI, PubMed, Web of Science and Google Scholar from the establishment of the database until January 2024 and summarize the diagnosis and clinical characteristics of hereditary angioed in children. Results: Case 1, female, 12 years old, presented with intermittent abdominal pain for 8 years, aggravated with vomiting for 2 days. Eight years ago, without a clear cause, case 1 experienced abdominal pain and underwent two abdominal surgeries. The concentration of C1 esterase inhibitor was 0.46 g/L, and the function of C1 esterase inhibitor was less than 0.01. The SERPING1 gene had a c.1396C>G variation, and she was diagnosed with hereditary angioedema type Ⅱ. Among the other 13 family members, 8 had swelling in different parts, and 2 had died. Case 2, female, 17 years old, was diagnosed with hereditary angioedema type Ⅰ due to intermittent limb swelling for more than 2 years. She had C4 of 0.09 g/L, C1 esterase inhibitor concentration of 0.05 g/L, C1 esterase inhibitor function <0.01, SERPING1 gene c.882C>G variation. Two out of the other 12 family members experienced intermittent skin swelling. Literature review meets the search criteria with 0 Chinese literature and 15 English literature, including a total of 524 cases of hereditary angioedema in children. Combined with 2 families in this group, there are 5 families with hereditary angioedema in children as the proband. The onset time is 1-15 years old, and the diagnosis delay time is -0.9 to 20.0 years. Two hundred and sixty-three cases (50.2%) of the children had a family history survey, of which 229 cases (87.1%) had a positive family history. Two hundred and fifty-seven cases (49.0%) had clear disease classification, with type Ⅰ being the main type, accounting for 234 cases (91.1%). The clinical symptoms of 296 children (56.5%) were described in detail, including 262 cases (88.5%) with skin edema in different parts, 176 cases (59.5%) with abdominal pain, and 61 cases (20.6%) with upper respiratory tract edema in the throat. Conclusions: Hereditary angioedema is mainly characterized by episodic skin and mucosal swelling, with individualized differences in the locations and characteristics of the onset. Hereditary angioedema in children is often overlooked, and patients with a positive family history of episodic skin and mucosal swelling need to actively undergo complement level testing.

The Crystal Structure of the Michaelis-Menten Complex of C1 Esterase Inhibitor and C1s Reveals Novel Insights into Complement Regulation.

The ancient arm of innate immunity known as the complement system is a blood proteolytic cascade involving dozens of membrane-bound and solution-phase components. Although many of these components serve as regulatory molecules to facilitate controlled activation of the cascade, C1 esterase inhibitor (C1-INH) is the sole canonical complement regulator belonging to a superfamily of covalent inhibitors known as serine protease inhibitors (SERPINs). In addition to its namesake role in complement regulation, C1-INH also regulates proteases of the coagulation, fibrinolysis, and contact pathways. Despite this, the structural basis for C1-INH recognition of its target proteases has remained elusive. In this study, we present the crystal structure of the Michaelis-Menten (M-M) complex of the catalytic domain of complement component C1s and the SERPIN domain of C1-INH at a limiting resolution of 3.94 Å. Analysis of the structure revealed that nearly half of the protein/protein interface is formed by residues outside of the C1-INH reactive center loop. The contribution of these residues to the affinity of the M-M complex was validated by site-directed mutagenesis using surface plasmon resonance. Parallel analysis confirmed that C1-INH-interfacing residues on C1s surface loops distal from the active site also drive affinity of the M-M complex. Detailed structural comparisons revealed differences in substrate recognition by C1s compared with C1-INH recognition and highlight the importance of exosite interactions across broader SERPIN/protease systems. Collectively, this study improves our understanding of how C1-INH regulates the classical pathway of complement, and it sheds new light on how SERPINs recognize their cognate protease targets.

Long term outcome of C1-esterase inhibitor deficiency.

Hereditary angioedema (HAE) is a rare hereditary disorder characterized by episodic swelling and life-threatening airway obstruction caused by laryngeal angioedema. In most HAE patients, reduced level of serum C1-Inhibitor (type-I-HAE) or presence of aberrant C1-Inhibitor (type-II-HAE) result in the lost of regulation of the complementary system and contact activation system with downstream over-activation of bradykinin - the chief mediator leading to angioedema. Type-III HAE (HAE-nl-C1INH) is rare without deficient or dysfunction of C1-Inhibitor, often with genetic aberrant related to the contact activation system. The prevalence of HAE in the population is estimated at 1 in 50,000 individuals, often with early onset, but due to the heterogeneity of the disease, there is frequently a significant delay in diagnosis. Recently, better awareness by physicians, more access to diagnostic tools, better management and prophylaxis has decreased morbidity and mortality. A focus in HAE patient care shift from management of attacks with on-demand medication, to use of prophylaxis to reduce attacks has improved the overall quality of life of patients with HAE. One area in HAE research that has not been emphasized is the long-term consequence of C1-INH deficiency in HAE patients, other than the typical manifestations of HAE, as evidence have emerged linking this disorder with increased risk of cardiovascular diseases, auto-immune disorders, and malignancy. This review aims to gather the current knowledge and evidence of potential consequence of C1-Inhibitor deficiency in HAE aside from angioedema with emphasis in the improvement of long-term care and overall quality of life for HAE patients.

Angioedema due to Acquired C1-Inhibitor Deficiency Associated With Monoclonal Gammopathies of Undetermined Significance Characteristics of a French National Cohort

No specific description of monoclonal gammopathies of undetermined significance (MGUS)-associated angioedema due to acquired C1 inhibitor deficiency (AAE-C1-INH) has been reported yet. Describe the biological and clinical characteristics, evolution and response to treatment of MGUS-associated AAE-C1-INH. We conducted a French national retrospective observational study on MGUS-associated acquired angioedema spanning a 30-year period. Forty-one patients with MGUS-associated AAE-C1-INH at diagnosis were included; 68% displayed anti-C1INH antibodies. The monoclonal component was an IgM in 24 patients, IgG in 11 and IgA in 6 patients. Mean age at first angioedema attack was 63 years (SD = 13) and at diagnosis 66 years (SD = 11). 88 % of patients benefited from acute attack treatments, and 77% from long-term prophylaxis, either danazol, tranexamic acid or lanadelumab. Median follow-up was 7 years, during which 14 patients (33%) evolved into well-defined malignant hemopathies. 50 % of patients were given a hematological treatment, either rituximab alone, indicated by recurrent attacks of angioedema in patients with AAE-C1-INH with anti-C1-INH antibodies, or validated combinations of chemotherapies, indicated by evolution into a lymphoma in 7 patients and a myeloma in 3 patients. Fifteen patients (35%) were in clinical complete remission of angioedema at last visit, of which 60% had an undetectable serum monoclonal immunoglobulin. Complete remission of AAE-C1-INH is correlated to complete remission of the underlying hematological malignancy, as defined by an undetectable serum monoclonal immunoglobulin. In our MGUS-associated acquired angioedema cohort, we recorded an incidence of evolution into hematological malignancy of 4% per patient-year. It is therefore crucial to conduct full hematological workup during follow-up at an annual rate, and earlier if AAE relapses or if acute attacks frequency increases.

Association of Endothelial Cell Activation with Acute Kidney Injury during Coronary Angiography and the Influence of Recombinant Human C1 Inhibitor-A Secondary Analysis of a Randomized, Placebo-Controlled, Double-Blind Trial.

Acute kidney injury (AKI) as a result of iodinated contrast media (CM) has been linked to CM-induced renal ischemia and toxic effects on endothelial cells (EC). The recombinant human C1 inhibitor (rhC1INH) has been shown to influence EC activation. Secondary analysis of 74/77 (96%) participants of a double-blind, randomized, and placebo-controlled study that assessed the effect of rhC1INH on AKI. E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule (VCAM-1), and CC-chemokin-ligand-5 (CCL5) were determined in frozen blood samples over 48 h and analyzed according to the treatment group and renal outcomes. The mean age was 76.7 years, and 37 patients each received rhC1INH and placebo, respectively. In the entire study population, minor differences in median EC activation markers/CCL5 concentrations during the first 48 h compared to baseline were observed (e.g., E-selectin 27.5 ng/mL at baseline vs. 29.7 ng/mL on day 1, CCL5: 17.7 ng/mL at baseline vs. 32.2 ng/mL on day 2). Absolute changes in ICAM-1/E-selectin concentrations correlated with a higher peak change in urinary NGAL concentrations. However, AKI was not associated with significant changes in EC markers/CCL5. Last, no significant differences in serum concentrations of EC activation markers/CCL5 were evident between the placebo and the rhC1INH group. CM administration during coronary angiography only mildly activated ECs within the first 48 h, which does not explain subsequent AKI. The administration of rhC1INH was not associated with a reduction of EC activation or CCL5.

Understanding the Role of the Complement System in Insulin Resistance and Metabolic Syndrome in Patients With Rheumatoid Arthritis.

The complement system has been associated with the etiopathogenesis of rheumatoid arthritis (RA). Insulin resistance (IR) and metabolic syndrome (MetS) are prevalent among patients with RA. The aim of this study was to explore the relationship between a comprehensive evaluation of the complement system and IR, as well as MetS, in patients with RA. A total of 339 nondiabetic patients with RA were recruited. Functional assays of the 3 complement pathways were assessed. Additionally, serum levels of the following individual components of the complement system were measured: C1q (classical); lectin (lectin); C2, C4, and C4b (classical lectin); factor D and properdin (alternative); C3 and C3a (common); C5, C5a, and C9 (terminal); as well as the factor I and C1 inhibitor regulators. IR and β cell function indices were calculated using the homeostatic model assessment. Criteria for MetS were applied. Multivariable linear regression analysis was performed to investigate the association between the complement system and IR in patients with RA. Many elements of the upstream and common complement pathways, but not the functional tests of the 3 routes, correlated positively with higher levels of IR and β cell function. However, after multivariable adjustment for factors associated with IR, these relationships were lost. Conversely, the presence of MetS in patients with RA maintained a relationship with higher levels of C1q, C4, C3, properdin, and factor I after adjusting for confounders. There is a positive correlation between the complement system and MetS among nondiabetic patients with RA. This association is independent of traditional IR factors.

Determinants of Disease Activity in Adults With Hereditary Angioedema due to C1-Esterase Inhibitor Deficiency.

Determinants of Disease Activity in Adults With Hereditary Angioedema due to C1-Esterase Inhibitor Deficiency.

Centralized care model for hereditary angioedema overcomes geographical barriers.

Hereditary angioedema due to C1 inhibitor deficiency (HAE) is a rare inborn error of immunity that presents with episodic swelling. Management is multifaceted and includes on-demand treatment of swelling episodes, short-term prophylaxis to prevent swelling episodes from procedures, and long-term prophylaxis (LTP) to prevent angioedema on an ongoing basis. All approved on-demand therapies are parenteral, necessitating patient training for home administration, particularly intravenous C1 inhibitor. These complexities can result in care gaps for rural HAE patients. We conducted a cross-sectional study at our Angioedema Center of Reference and Excellence to assess the care provided to urban and rural patients. The proportion of patients receiving LTP, proportion of patients diagnosed as children, and disease control measured using the Angioedema Control Test (AECT) were collected. Logistic and Poisson regression models adjusted for age and sex were used to compare the two groups. The proportion using LTP was similar at 62% and 61% in urban and rural patients, respectively (odds ratio [OR] 1.01 (CI 95% 0.34-2.99)). Among urban patients, 52% were diagnosed as children compared to 60% among rural residents (1.43 (0.37-5.56)). The mean (IQR) AECT score was 14.0 (8.5-15.5) in urban patients and 13.0 (10.0-14.0) in rural patients (Poisson β -0.001 (-0.23-0.23). These data indicate that rural patients received similar high-quality care. We attribute these findings to the centralized care model employed in which HAE patients in the region are seen at a single comprehensive care clinic.