C-reactive protein levels in hereditary angioedema

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.

Biomarkers in Hereditary Angioedema

A biomarker is a defined characteristic measured as an indicator of normal, biologic, pathogenic processes, or biological responses to an exposure or intervention. Diagnostic biomarkers are used to detect a disease or a subtype of a disease; monitoring biomarkers are measured serially to assess a medical condition; response biomarkers are used to check biologic response following a medical intervention; predictive biomarkers are used to identify patients who are more likely to respond to a medical intervention; and prognostic biomarkers are used to assess the future likelihood of a clinical event. Although biomarkers have been extensively investigated and validated in many diseases and pathologies, very few are currently useful for the diagnosis, evaluation of disease activity, and treatment of hereditary angioedema (HAE). Pathophysiologic pathways involved in HAE reveal a plethora of molecules from the complement, coagulation, and fibrinolysis systems or from the vascular endothelium, which may serve as biomarkers. The most promising candidates, together with their laboratory readout systems, should be evaluated with regard to their analytical and clinical validity and utility. To be highly specific, such biomarkers should be linked to the pathomechanisms of HAE, particularly the bradykinin-generating cascade. Additionally, major advances in high-throughput omics-based technologies may facilitate the discovery of new candidate biomarkers in the future. This review will cover the existing as well as future potential biomarkers that will support the diagnosis, monitor disease activity, and can be used to assess the efficacy of new avenues of therapy of HAE and other forms of angioedema.

Can the neutrophil-lymphocyte ratio predict type 1 hereditary angioedema attacks?

The neutrophil-lymphocyte ratio is a simple and easily used parameter for the assessment of inflammation. We aimed to determine the predictive potential of the neutrophil-lymphocyte ratio regarding episode occurrence in patients with hereditary angioedema. Sixty-six patients with Type 1 hereditary angioedema and 60 healthy controls were included in the study. The laboratory results of the patients in their episode-free periods were similar to those of the healthy controls. The median of neutrophil-lymphocyte ratio was higher during episodes when compared to normal periods (3.5 versus 2.0, p < .001). A significant positive correlation was present between the episode count and the neutrophil-lymphocyte ratio calculated during the episodes (r = 0.557, p < .001). We can conclude that the neutrophil-lymphocyte ratio, which is cheap and easy to calculate, can be used by clinicians as a predictive parameter for prediction of the episode count in patients with hereditary angioedema.

Serum fetuin-A, tumor necrosis factor alpha and C-reactive protein concentrations in patients with hereditary angioedema with C1-inhibitor deficiency

Background and aims

Hereditary angioedema with C1-inhibitor deficiency (C1-INH-HAE) is characterized by localized, non-pitting, and transient swelling of submucosal or subcutaneous region. Human fetuin-A is a multifunctional glycoprotein that belongs to the proteinase inhibitor cystatin superfamily and has structural similarities to the high molecular weight kininogen. Fetuin-A is also known a negative acute phase reactant with anti-inflammatory characteristics. In this study we aimed to determine serum fetuin-A, C-reactive protein (CRP) and tumor necrosis factor alpha (TNFα) concentrations in patients with C1-INH-HAE during symptom-free period and during attacks and compare them to those of healthy controls. Further we analyzed possible relationship among these parameters as well as D-dimer levels which was known as marker of HAE attacks.

Patients and methods

Serum samples of 25 C1-INH-HAE patients (8 men, 17 women, age: 33.1 ± 6.9 years, mean ± SD) were compared to 25 healthy controls (15 men, 10 women, age: 32.5 ± 7.8 years). Serum fetuin-A and TNFα concentrations were determined by ELISA, CRP and D-dimer by turbidimetry.

Results

Compared to healthy controls patients with C1-INH-HAE in the symptom-free period had significantly decreased serum fetuin-A 258 μg/ml (224–285) vs. 293 μg/ml (263–329), (median (25–75% percentiles, p = 0.035) and TNFα 2.53 ng/ml (1.70–2.83) vs. 3.47 ng/ml (2.92–4.18, p = 0.0008) concentrations. During HAE attacks fetuin-A levels increased from 258 (224–285) μg/ml to 287 (261–317) μg/ml (p = 0.021). TNFα and CRP levels did not change significantly. We found no significant correlation among fetuin-A CRP, TNFα and D-dimer levels in any of these three groups.

Conclusions

Patients with C1-INH-HAE have decreased serum fetuin-A concentrations during the symptom-free period. Given the anti-inflammatory properties of fetuin-A, the increase of its levels may contribute to the counter-regulation of edema formation during C1-INH-HAE attacks.

The complex alteration in the network of IL-17-type cytokines in patients with hereditary angioedema

Hereditary angioedema (HAE) is a rare autosomic-dominant disorder characterized by a deficiency of C1 esterase inhibitor which causes episodic swellings of subcutaneous tissues, bowel walls and upper airways that are disabling and potentially life-threatening. We evaluated n = 17 patients with confirmed HAE diagnosis during attack and remission state and n = 19 healthy subjects. The samples were tested for a panel of IL (Interleukin)-17-type cytokines (IL-1β, IL-6, IL-10, granulocyte-macrophage colony stimulating factor (GM-CSF), IL-17, IL-21, IL-22, IL-23) and transforming growth factor-beta (TGF-β) subtypes. Data indicate that there are variations of cytokine levels in HAE subjects comparing the condition during the crisis respect to the value in the remission phase, in particular type 17 signature cytokines are increased, whereas IL-23 is unmodified and TGF-β3 is significantly reduced. When comparing healthy and HAE subjects in the remission state, we found a significant difference for IL-17, GM-CSF, IL-21, TGF-β1 and TGF-β2 cytokines. These results confirm and extend our previous findings indicating that in HAE there is operating an inflammatory activation process, which involves also T helper 17 (Th17) cytokines and TGF-β isoforms, associated with localized angioedema attacks and characterized by elevated bradykinin levels.

Secreted Phospholipases A2 in Hereditary Angioedema With C1-Inhibitor Deficiency

Background

Hereditary angioedema (HAE) caused by deficiency (type I) or dysfunction (type II) of the C1 inhibitor protein (C1-INH-HAE) is a disabling, potentially fatal condition characterized by recurrent episodes of swelling. We have recently found that patients with C1-INH-HAE have increased plasma levels of vascular endothelial growth factors and angiopoietins (Angs), which have been associated with vascular permeability in several diseases. Among these and other factors, blood endothelial cells and vascular permeability can be modulated by extracellular or secreted phospholipases A₂ (sPLA₂s).

Objective

We sought to investigate the enzymatic activity and biological functions of sPLA₂ in patients with C1-INH-HAE.

Methods

sPLA₂s enzymatic activity was evaluated in the plasma from 109 adult patients with C1-INH-HAE and 68 healthy donors in symptom-free period and attacks. Plasma level of group IIA sPLA₂ (hGIIA) protein was measured in selected samples. The effect of C1-INH-HAE plasma on endothelial permeability was examined in vitro using a vascular permeability assay. The role of hGIIA was determined using highly specific sPLA₂ indole inhibitors. The effect of recombinant hGIIA on C1-INH activity was examined in vitro by functional assay.

Results

Plasma sPLA₂ activity and hGIIA levels are increased in symptom-free C1-INH-HAE patients compared with controls. sPLA₂ activity negatively correlates with C1-INH protein level and function. C1-INH-HAE plasma increases endothelial permeability in vitro, and this effect is partially reverted by a specific hGIIA enzymatic inhibitor. Finally, recombinant hGIIA inhibits C1-INH activity in vitro.

Conclusion

sPLA₂ enzymatic activity (likely attributable to hGIIA), which is increased in C1-INH-HAE patients, can promote vascular permeability and impairs C1-INH activity. Our results may pave the way for investigating the functions of sPLA₂s (in particular, hGIIA) in the pathophysiology of C1-INH-HAE and may inform the development of new therapeutic targets.

"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.

Hereditary Angioedema Attacks: Local Swelling at Multiple Sites

Hereditary angioedema (HAE) patients experience recurrent local swelling in various parts of the body including painful swelling of the intestine and life-threatening laryngeal oedema. Most HAE literature is about attacks located in one anatomical site, though it is mentioned that HAE attacks may also involve multiple anatomical sites simultaneously. A detailed description of such multi-location attacks is currently lacking. This study investigated the occurrence, severity and clinical course of HAE attacks with multiple anatomical locations. HAE patients included in a clinical database of recombinant human C1-inhibitor (rhC1INH) studies were evaluated. Visual analog scale scores filled out by the patients for various symptoms at various locations and investigator symptoms scores during the attack were analysed. Data of 219 eligible attacks in 119 patients was analysed. Thirty-three patients (28%) had symptoms at multiple locations in anatomically unrelated regions at the same time during their first attack. Up to five simultaneously affected locations were reported. The observation that severe HAE attacks often affect multiple sites in the body suggests that HAE symptoms result from a systemic rather than from a local process as is currently believed.

The isolated human umbilical vein as a bioassay for kinin-generating proteases: An in vitro model for therapeutic angioedema agents

AIMS

The isolated human umbilical vein is a robust contractile bioassay for ligands of the bradykinin (BK) B2 receptor (B2R), also extendable to B1 receptor (B1R) pharmacology. We hypothesized that, as a freshly isolated vessel, it also contains traces of plasma proteins that may confer responses to exogenous proteases via the formation of kinins.

MAIN METHODS

Rings of human umbilical veins were mounted in organ baths containing Krebs buffer maintained at 37°C and purified proteases were introduced in the bathing fluid along with additional drugs/proteins that permit mechanistic analysis of effects.

KEY FINDINGS

The previously described contractile response to human recombinant tissue kallikrein (KLK-1, 1-10nM) is not influenced by metabolic inhibitors, suggesting its dependence on a preexisting reservoir of low molecular weight-kininogen (LK). Active plasma kallikrein (apK, ≤5nM) was inactive in fresh tissues, unless high molecular weight-kininogen (HK, 39-197nM) replenishment was applied. The effects of KLK-1 and HK+apK are abolished by pretreating tissues with icatibant, but not with tranexamic acid. C1-esterase inhibitor inhibited only HK+apK. Purified plasmin and neutrophil proteinase-3 produced small contractions in the presence of HK only, and tissue plasminogen activator, none. B1R stimulation was pharmacologically evidenced in response to KLK-1 if LK was supplied.

SIGNIFICANCE

The pharmacology of KLK-1 and HK+apK in the human isolated umbilical vein is essentially based on the activity of locally generated kinins and this assay models the inhibitory action of some therapeutic agents active in angioedema states. Proteases that indirectly generate kinins have little activity in the system.

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

BACKGROUND

Earlier 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.

METHODS

We 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.

RESULTS

NGC 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.

CONCLUSION

Increased 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.

Hereditary Angioedema and Gastrointestinal Complications: An Extensive Review of the Literature

Hereditary Angioedema (HAE) is a rare autosomal dominant (AD) disease characterized by deficient (type 1) or nonfunctional (type 2) C1 inhibitor protein. The disorder is associated with episodes of angioedema of the face, larynx, lips, abdomen, or extremities. The angioedema is caused by the activation of the kallikrein-kinin system that leads to the release of vasoactive peptides, followed by edema, which in severe cases can be life threatening. The disease is usually not diagnosed until late adolescence and patients tend to have frequent episodes that can be severely impairing and have a high incidence of morbidity. Gastrointestinal involvement represents up to 80% of clinical presentations that are commonly confused with other gastrointestinal disorders such as appendicitis, cholecystitis, pancreatitis, and ischemic bower. We present a case of an HAE attack presenting as colonic intussusception managed conservatively with a C1 esterase inhibitor. Very few cases have been reported in the literature of HAE presentation in this manner, and there are no reports of any nonsurgical management of these cases.