Co-occurrence between C1 esterase inhibitor deficiency and autoimmune disease: a systematic literature review

Comorbidities in Angioedema Due to C1-Inhibitor Deficiency: An Italian Survey

BACKGROUND

Hereditary angioedema (HAE) due to C1-inhibitor (C1-INH) deficiency is characterized by unpredictable recurrent episodes of swelling affecting the skin and the mucosa tissues, including gastrointestinal tract and/or oropharyngeal-laryngeal mucosae. Long-term prophylaxis (LTP) is used to prevent attacks.

OBJECTIVE

Because C1-INH plays a pivotal role in several biological pathways, we investigated the possible association of comorbidities with C1-INH deficiency and the use of LTP with attenuated androgens (AA) or tranexamic acid (TXA).

METHODS

This retrospective cohort study involved adult patients with HAE referred to Milan and Padua angioedema centers in the period 1979-2021. A qualitative comparison was performed to analyze comorbidities versus general population. The incidence of comorbidities was evaluated during LTP with AA or TXA versus patients without LTP.

RESULTS

A total of 446 patients were studied. A greater prevalence among patients was found for heart diseases (9.6% vs 4.8%), acute myocardial infarction (5.6% vs 1.4%), hepatitis C virus infection (10.5% vs 2.5%), and appendectomy (15.9% vs 4.3%). In patients taking AA, a greater incidence was found for hypertension (22.8% vs 10.8%; odds ratio [OR]: 2.02), hypercholesterolemia (19.5% vs 5.3%; OR: 3.97), diabetes mellitus (5% vs 1.4%; OR: 3.21), hepatic angioma (4.4% vs 0.7%; OR: 8.35), and focal nodular hyperplasia (2.5% vs 0.4%; OR: 6.9). No association between TXA and comorbidities was found.

CONCLUSION

In this large patient population with a rare disease followed for up to a 43-year period, we found a greater prevalence of comorbidities hitherto unreported in the literature and an association between comorbidities and LTP with AA.

An expert panel's review on patients with hereditary angioedema switching from attenuated androgens to oral prophylactic therapy

Background: Hereditary angioedema (HAE) is a rare condition marked by swelling episodes in various body parts, including the extremities, upper airway, face, intestinal tract, and genitals. Long-term prophylaxis (LTP), prescribed to control recurring HAE attacks, is integral to its management. Previously, attenuated androgens (AAs) were the only oral LTP options. However, in 2020, berotralstat, an oral plasma kallikrein inhibitor, was approved in the United States. A 2018 survey of adults with HAE type I or type II showed that almost all the patients who used prophylactic HAE medication preferred oral treatment (98%) and felt that it fit their lifestyle better than injectable treatment (96%). Still, guidelines lack consensus on transitioning patients from AAs to alternative oral prophylactic therapy. Objective: This paper aims to share expert insights and patient feedback on transitioning from AAs to berotralstat, an alternative oral prophylactic therapy, from the perspective of clinicians with extensive experience in treating patients with HAE. Methods: A panel of five HAE specialists convened for a virtual half-day roundtable discussion in April 2023. Results: Discussions about transitioning from AAs to berotralstat were prompted by routine consultations, patient inquiries based on independent research, ineffective current treatment, or worsening AA-related adverse effects. For patients who switched from AAs, the physicians reported that the decision was influenced by the alternative therapy's ability to prevent HAE attacks, its safety, and the once-daily administration schedule. All expert panel members identified fewer AA-related adverse effects; better quality of life; and less severe, shorter, and less frequent HAE attacks as clinical or patient goals they hoped to achieve through the treatment switch. Conclusion: The emergence of new, highly specific LTP drugs for HAE calls for the development of comprehensive recommendations and guidelines for transitioning from AAs to alternative oral prophylactic therapy. The expert panel highlighted key factors to consider during the development of such guidelines.

Sir William Osler's fatal trip to Scotland: "Mrs M" and the University Grants Committee

On 23 September 1919, Sir William Osler, after a telephone call from his friend Dyson Perrins, went to Glasgow where he saw a 40-year-old woman, Bethia Fulton Martin, in consultation with three local physicians. Osler called it "one of those remarkable Erythema cases (all sorts of skin lesions and three months on and off consolidation of both lower lobes)." Mrs Martin died 114 days later; her death certificate listed "angioneurotic oedema with chronic nephritis" and "tuberculous enlargement of the mediastinal lymph nodes." Osler died 18 days before Mrs Martin of complications from a respiratory infection acquired on his way home from Scotland. We discuss factors that possibly prompted Osler to go to Scotland, including his role with the newly formed University Grants Committee, and the differential diagnosis of the case, which is mainly between systemic lupus erythematosus and Henoch-Schönlein purpura.

The role of C5a receptors in autoimmunity

The complement system is an essential component of the innate immune response and plays a vital role in host defense and inflammation. Dysregulation of the complement system, particularly involving the anaphylatoxin C5a and its receptors (C5aR1 and C5aR2), has been linked to several autoimmune diseases, indicating the potential for targeted therapies. C5aR1 and C5aR2 are seven-transmembrane receptors with distinct signaling mechanisms that play both partially overlapping and opposing roles in immunity. Both receptors are expressed on a broad spectrum of immune and non-immune cells and are involved in cellular functions and physiological processes during homeostasis and inflammation. Dysregulated C5a-mediated inflammation contributes to autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, epidermolysis bullosa acquisita, antiphospholipid syndrome, and others. Therefore, targeting C5a or its receptors may yield therapeutic innovations in these autoimmune diseases by reducing the recruitment and activation of immune cells that lead to tissue inflammation and injury, thereby exacerbating the autoimmune response. Clinical trials focused on the inhibition of C5 cleavage or the C5a/C5aR1-axis using small molecules or monoclonal antibodies hold promise for bringing novel treatments for autoimmune diseases into practice. However, given the heterogeneous nature of (systemic) autoimmune diseases, there are still several challenges, such as patient selection, optimal dosing, and treatment duration, that require further investigation and development to realize the full therapeutic potential of C5a receptor inhibition, ideally in the context of a personalized medicine approach. Here, we aim to provide a brief overview of the current knowledge on the function of C5a receptors, the involvement of C5a receptors in autoimmune disorders, the molecular mechanisms underlying C5a receptor-mediated autoimmunity, and the potential for targeted therapies to modulate their activity.

The multifactorial impact of receiving a hereditary angioedema diagnosis

Hereditary angioedema (HAE) is a rare, chronic, debilitating genetic disorder characterized by recurrent, unpredictable, and potentially life-threatening episodes of swelling that typically affect the extremities, face, abdomen, genitals, and larynx. The most frequent cause of HAE is a mutation in the serpin family G member 1 (SERPING1) gene, which either leads to deficient plasma levels of the C1-esterase inhibitor (C1-INH) protein (type I HAE-C1-INH) or normal plasma levels of dysfunctional C1-INH protein (type II HAE-C1-INH). Mutations in SERPING1 are known to be associated with dysregulation of the kallikrein-bradykinin cascade leading to enhancement of bradykinin production and increased vascular permeability. However, some patients present with a third type of HAE (HAE-nl-C1-INH) that is characterized by normal plasma levels and functionality of the C1-INH protein. While mutations in the factor XII, angiopoietin-1, plasminogen, kininogen-1, myoferlin, and heparan sulfate-glucosamine 3-O-sulfotransferase-6 genes have been identified in some patients with HAE-nI-C1-INH, genetic cause remains unknown in many cases with further research required to fully elucidate the pathology of disease in these patients. Here we review the challenges that arise on the pathway to a confirmed diagnosis of HAE and explore the multifactorial impact of receiving a HAE diagnosis. We conclude that it is important to continue to raise awareness of HAE because delays to diagnosis have a direct impact upon patient suffering and quality of life. Since many patients will seek help from hospitals during their first swelling attack it is vital that emergency department staff are aware of the different pathological pathways that distinguish HAE from other forms of angioedema to ensure that the most appropriate treatment is administered. As disease awareness increases, it is hoped that patients will be diagnosed earlier and that pre-authorization and insurance coverage of HAE treatments will become easier to obtain, ultimately reducing the burden of treatment for these patients and their caregivers.

A Review of Randomized Controlled Trials of Hereditary Angioedema Long-Term Prophylaxis with C1 Inhibitor Replacement Therapy: Alleviation of Disease Symptoms Is Achievable

Through its fluctuating disease activity and unpredictable attacks, hereditary angioedema (HAE) imposes a substantial patient burden. To minimize HAE burden and improve quality of life, treatment should involve individualized management strategies that address on-demand therapy and short-term/long-term prophylaxis. Goals of long-term prophylaxis include reducing the number, severity, and burden of HAE attacks. The best characterized forms of HAE arise from deficiency or dysfunction of C1-inhibitor (C1-INH; types I/II), and C1-INH replacement therapy is a first-line intervention for on-demand (acute) treatment of HAE attacks, short-term prophylaxis before high-risk procedures, and long-term prophylaxis. Randomized, double-blind, placebo-controlled crossover trials have shown dose-dependent efficacy with plasma-derived C1-INH (pdC1-INH) 40-60 IU/kg subcutaneously, pdC1-INH 1000 U intravenously, and recombinant human C1-INH (rhC1-INH) 50 IU/kg (maximum 4200 IU) intravenously, all administered twice weekly, as long-term prophylaxis in patients with a history of 2 to ≥4 attacks/month. Overall, up to 83% (pdC1-INH 60 IU/kg) of patients experienced an HAE attack reduction threshold of ≥70%, and up to 58% (pdC1-INH 60 IU/kg) achieved an attack reduction threshold of ≥90%. Lower-dose intravenous pdC1-INH therapy (1000 U) was seemingly less effective, with 45% of 22 patients experiencing an HAE attack reduction threshold of ≥70%, and up to 23% achieving an attack reduction threshold of ≥90%. Higher-dose intravenous rhC1-INH 50 IU/kg (maximum, 4200 IU) twice weekly was of intermediate benefit. Despite a baseline mean attack frequency of 17.9 (during the 3 months prior to study treatment) and a mean attack frequency during a 4-week placebo period of 7.2, 52% of 23 patients experienced ≥70% reduction in attack frequency and 26% of 23 patients experienced ≥90% reduction in attack frequency. The increasing patient percentages treated with C1-INH replacement therapy as long-term prophylaxis meeting these high thresholds reinforces hopes and expectations that "attack freedom" is achievable, including for those with moderate or severe disease.

High Throughput Genetic Characterisation of Caucasian Patients Affected by Multi-Drug Resistant Rheumatoid or Psoriatic Arthritis

Rheumatoid and psoriatic arthritis (RA and PsA) are inflammatory rheumatic disorders characterised by a multifactorial etiology. To date, the genetic contributions to the disease onset, severity and drug response are not clearly defined, and despite the development of novel targeted therapies, ~10% of patients still display poor treatment responses. We characterised a selected cohort of eleven non-responder patients aiming to define the genetic contribution to drug resistance. An accurate clinical examination of the patients was coupled with several high-throughput genetic testing, including HLA typing, SNPs-array and Whole Exome Sequencing (WES). The analyses revealed that all the subjects carry very rare HLA phenotypes which contain HLA alleles associated with RA development (e.g., HLA-DRB1*04, DRB1*10:01 and DRB1*01). Additionally, six patients also carry PsA risk alleles (e.g., HLA-B*27:02 and B*38:01). WES analysis and SNPs-array revealed 23 damaging variants with 18 novel “drug-resistance” RA/PsA candidate genes. Eight patients carry likely pathogenic variants within common genes (CYP21A2, DVL1, PRKDC, ORAI1, UGT2B17, MSR1). Furthermore, “private” damaging variants were identified within 12 additional genes (WNT10A, ABCB7, SERPING1, GNRHR, NCAPD3, CLCF1, HACE1, NCAPD2, ESR1, SAMHD1, CYP27A1, CCDC88C). This multistep approach highlighted novel RA/PsA candidate genes and genotype-phenotype correlations potentially useful for clinicians in selecting the best therapeutic strategy.

Systemic lupus erythematosus with various clinical manifestations in a patient with hereditary angioedema: a case report

Background

Hereditary angioedema (HAE) is an inherited disease characterized by recurrent angioedema without urticaria or pruritus. The most common types of HAE are caused by deficiency or dysfunction in C1 esterase inhibitor (C1-INH-HAE). The association between C1-INH-HAE and systemic lupus erythematosus (SLE) is known; however, variations in the underlying pathophysiology, disease course, and treatment in this population remain incompletely understood.

Case presentation

A 31-year-old Japanese woman with a prior diagnosis of HAE type 1 based on the episodes of recurrent angioedema, low C1 inhibitor antigen levels and function, and family history presented with new complaints of malar rash, alopecia, and arthralgias in her hands and elbows. She later developed fever, oral ulcers, lupus retinopathy, a discoid rash localized to her chest, and malar rash. Investigations revealed positive antinuclear antibody, leukopenia, thrombocytopenia, hypocomplementemia, and nephritis. Based on these findings, she was diagnosed with SLE according to the 2019 European League Against Rheumatism/American College of Rheumatology classification criteria. There did not appear to be a correlation between HAE disease activity and the timing of presentation with SLE, because HAE disease activity had been stable. The patient was able to achieve and maintain remission with immunosuppressive therapy including prednisolone, hydroxychloroquine, and tacrolimus.

Conclusions

Our patient presented with a variety of symptoms, including fever and cytopenia in addition to mucocutaneous, joint, ocular, and renal lesions. It is important to better characterize the clinical characteristics of SLE in patients with C1-INH-HAE, and to clarify the mechanisms of SLE in this population.

Comorbidities in hereditary angioedema-A population-based cohort study

Background

In hereditary angioedema (HAE), low levels (type 1) or defect in function (type 2) of the serine‐protease inhibitor C1 Inhibitor protein results in activation of the classical pathway of the complement system as well as the contact system. Here, we investigated the risk of comorbidities in HAE.

Methods

Individuals with HAE (n = 239; identified through a physician made diagnosis) and a control cohort from the general population (n = 2383; matched for age, gender, and county of residence) were compared with the Swedish inpatient, cause of death, cancer, and prescription registers. Conditional logistic regression was used to analyze the data.

Results

Increased risk of cardiovascular disease (odds ratio [OR] 1.83; 95% confidence interval [CI] 1.32–2.54), including arterial (OR 6.74; 95% CI 1.89–24.06) and venous thromboembolic disease (OR 4.20; 95% CI 2.42–7.23) as well as hypertension (OR 1.64; 95% CI 1.12–2.39) was seen in HAE. There was also an increased number of individuals diagnosed with hyperlipidemia (OR 2.01; 95% CI 1.16–3.50) among HAE patients. Furthermore, the risk of autoimmune disease was increased (OR 1.65; 95% CI 1.15–2.35) being particularly pronounced for systemic lupus erythematosus (OR 71.87; 95% CI 8.80–586.7). The risk of having two or more autoimmune diseases was also higher among HAE patients (p = 0.017). In contrast, the risk of cancer was not increased. Data from the prescription register revealed higher prescription rates of drugs against hypertension, hypothyroidism, and hyperlipidemia among HAE patients.

Conclusions

The results warrant for awareness and prevention of comorbid conditions, in particular, thromboembolic and autoimmune diseases in HAE. Future prophylactic interventions may modify these risks.

Malignancy and immune disorders in patients with hereditary angioedema

Background

Hereditary angioedema (HAE) is an inherited condition manifesting as recurrent angioedema episodes which is caused by deficiency or dysfunction of C1 inhibitor. Although complement dysregulation has historically been shown to be associated with various malignancy and immune disorders, it is currently not known if HAE patients are at an increased risk of developing malignancy or autoimmune conditions.

Case presentation

We reviewed the charts of 49 HAE patients and identified 6 patients who had a co-existing malignancy diagnosis (two with breast cancer, one with melanoma, one with pancreatic cancer, one with renal cancer and one with cervical dysplasia) and 6 patients who had a diagnosis of a co-existing immune disorder (two with rheumatoid arthritis, two with ulcerative colitis, one with chronic urticaria with hypothyroidism and one with Sjogren’s syndrome). Nearly all malignancy cases occurred in older HAE patients (> 50 years) and malignancy was diagnosed before HAE in 3 of the patients.

Conclusions

Our case series identified multiple hereditary angioedema (HAE) patients with co-existing malignancy and immune disorders. Based on these findings, we would advocate that physicians managing HAE patients should maintain a high index of suspicion for these conditions and that in patients with angioedema, C1 inhibitor deficiency and malignancy, a diagnosis of HAE should still be considered in addition to acquired angioedema (AAE).

COVID-19 and hereditary angioedema: Incidence, outcomes, and mechanistic implications

Background: Patients with hereditary angioedema (HAE) have been postulated to be at increased risk for coronavirus disease 2019 (COVID-19) infection due to inherent dysregulation of the plasma kallikrein-kinin system. Only limited data have been available to explore this hypothesis. Objective: To assess the interrelationship(s) between COVID-19 and HAE. Methods: Self-reported COVID-19 infection, complications, morbidity, and mortality were surveyed by using an online questionnaire. The participants included subjects with HAE with C1 inhibitor (C1INH) deficiency (HAE-C1INH) and subjects with HAE with normal C1-inhibitor (HAE-nl-C1INH), and household controls (normal controls). The impact of HAE medications was examined. Results: A total of 1162 participants who completed the survey were analyzed, including: 695 subjects with HAE-C1INH, 175 subjects with HAE-nl-C1INH, and 292 normal controls. The incidence of reported COVID-19 was not significantly different between the normal controls (9%) and the subjects with HAE-C1INH (11%) but was greater in the subjects with HAE-nl-C1INH (19%; p = 0.006). Obesity was positively correlated with COVID-19 across the overall population (p = 0.012), with a similar but nonsignificant trend in the subjects with HAE-C1INH. Comorbid autoimmune disease was a risk factor for COVID-19 in the subjects with HAE-C1INH (p = 0.047). COVID-19 severity and complications were similar in all the groups. Reported COVID-19 was reduced in the subjects with HAE-C1INH who received prophylactic subcutaneous C1INH (5.6%; p = 0.0371) or on-demand icatibant (7.8%; p = 0.0016). The subjects with HAE-C1INH and not on any HAE medications had an increased risk of COVID-19 compared with the normal controls (24.5%; p = 0.006). Conclusion: The subjects with HAE-C1INH who were not taking HAE medications had a significantly higher rate of reported COVID-19 infection. Subcutaneous C1INH and icatibant use were associated with a significantly reduced rate of reported COVID-19. The results implicated potential roles for the complement cascade and tissue kallikrein-kinin pathways in the pathogenesis of COVID-19 in patients with HAE-C1INH.

Demographic and clinical characteristics of patients with hereditary angioedema in Canada

BACKGROUND

Data on the clinical and demographic features of Canadian patients with hereditary angioedema (HAE) are lacking.

OBJECTIVE

To describe the clinical and demographic features in a large Canadian HAE cohort and compare them with patients with HAE in other countries.

METHODS

An online questionnaire was distributed to the members of 2 Canadian HAE patient groups to collect information on demographics and HAE clinical characteristics. All participants 18 years of age or older with HAE type I or II were eligible. Frequency, location, prodromes, and triggers of HAE attacks, including types of HAE treatment, were characterized.

RESULTS

Among the 90 participants who completed the online survey, 57% self-identified as having HAE type 1 and 26% HAE type II. The average diagnostic delay was 11 years. In the preceding 6 months, 24% of the participants had no attacks and 35% experienced greater than 5 attacks. The most frequently affected regions of the body were the abdomen (83%), arms orlegs (63%), face (41%), and larynx or throat (41%). Approximately 87% of the participants reported having access to C1 inhibitor at home, and 69% reported using it for long-term prophylaxis.

CONCLUSION

Canadian patients with HAE share common clinical characteristics with patients with HAE in other countries. They had a delay in HAE diagnosis and a high burden of disease, as indicated by the high frequency of attacks in the preceding 6 months. This study provides a better understanding of the demographic and clinical characteristics of Canadian patients with HAE.

Differentially Expressed Gene Pathways in the Conjunctiva of Sjögren Syndrome Keratoconjunctivitis Sicca

Sjögren syndrome (SS) is an autoimmune condition that targets the salivary and lacrimal glands, with cardinal clinical signs of dry eye (keratoconjunctivitis sicca, KCS) and dry mouth. The conjunctiva of SS patients is often infiltrated by immune cells that participate in the induction and maintenance of local inflammation. The purpose of this study was to investigate immune-related molecular pathways activated in the conjunctiva of SS patients. Female SS patients (n=7) and controls (n=19) completed a series of oral, ocular surface exams. Symptom severity scores were evaluated using validated questionnaires (OSDI and SANDE). All patients fulfilled the ACR/EULAR criteria for SS and the criteria for KCS. Fluorescein and lissamine green dye staining evaluated tear-break-up time (TBUT), corneal and conjunctival disease, respectively. Impression cytology of the temporal bulbar conjunctiva was performed to collect cells lysed and subjected to gene expression analysis using the NanoString Immunology Panel. 53/594 differentially expressed genes (DEGs) were observed between SS and healthy controls; 49 DEGs were upregulated, and 4 were downregulated (TRAF5, TGFBI, KLRAP1, and CMKLRI). The top 10 DEGs in descending order were BST2, IFITM1, LAMP3, CXCL1, IL19, CFB, LY96, MX1, IL4R, CDKN1A. Twenty pathways had a global significance score greater or equal to 2. Spearman correlations showed that 29/49 upregulated DEGs correlated with either TBUT (inverse) or OSDI or conjunctival staining score (positive correlations). Venn diagrams identified that 26/29 DEGs correlated with TBUT, 5/26 DEGs correlated with OSDI, and 16/26 correlated with conjunctival staining scores. Five upregulated DEGs (CFB, CFI, IL1R1, IL2RG, IL4R) were uniquely negatively correlated with TBUT. These data indicate that the conjunctiva of SS patients exhibits a phenotype of immune activation, although some genes could be inhibitory. Some of the DEGs and pathways overlap with previous DEGs in salivary gland biopsies, but new DEGs were identified, and some of these correlated with symptoms and signs of dry eye. Our results indicate that gene analysis of conjunctiva imprints is a powerful tool to understand the pathogenesis of SS and develop new therapeutic targets.

Heat-Inactivation of Human Serum Destroys C1 Inhibitor, Pro-motes Immune Complex Formation, and Improves Human T Cell Function

Heat-inactivation of sera is used to reduce possible disturbing effects of complement factors in cell-culture experiments, but it is controversially discussed whether this procedure is appropriate or could be neglected. Here, we report a strong impact of heat-inactivation of human sera on the activation and effector functions of human CD4+ T cells. While T cells cultured with native sera were characterized by a higher proliferation rate and higher expression of CD28, heat-inactivated sera shaped T cells towards on-blast formation, higher cytokine secretion (interferon γ, tumor necrosis factor, and interleukin-17), stronger CD69 and PD-1 expression, and increased metabolic activity. Heat-inactivated sera contained reduced amounts of complement factors and regulators like C1 inhibitor, but increased concentrations of circulating immune complexes. Substitution of C1 inhibitor reduced the beneficial effect of heat-inactivation in terms of cytokine release, whereas surface-molecule expression was affected by the addition of complex forming anti-C1q antibody. Our data clearly demonstrate a beneficial effect of heat-inactivation of human sera for T cell experiments but indicate that beside complement regulators and immune complexes other components might be relevant. Beyond that, this study further underpins the strong impact of the complement system on T cell function.