A monoclonal antibody to high-molecular weight kininogen is therapeutic in a rodent model of reactive arthritis

Severe high-molecular-weight kininogen deficiency: clinical characteristics, deficiency-causing KNG1 variants, and estimated prevalence

BACKGROUND

Severe high-molecular-weight kininogen (HK) deficiency is a poorly studied autosomal recessive contact system defect caused by pathogenic, biallelic KNG1 variants.

AIM

We performed the first comprehensive analysis of diagnostic, clinical, genetic, and epidemiological aspects of HK deficiency.

METHODS

We collected clinical information and blood samples from a newly detected HK-deficient individual and from published cases identified by a systematic literature review. Activity and antigen levels of coagulation factors were determined. Genetic analyses of KNG1 and KLKB1 were performed by Sanger sequencing. The frequency of HK deficiency was estimated considering truncating KNG1 variants from GnomAD.

RESULTS

We identified 48 cases of severe HK deficiency (41 families), of these 47 have been previously published (n = 19 from gray literature). We genotyped 3 cases and critically appraised 10 studies with genetic data. Ten HK deficiency-causing variants (one new) were identified. All of them were truncating mutations, whereas the only known HK amino acid substitution with a relevant phenotype instead causes hereditary angioedema. Conservative estimates suggest an overall prevalence of severe HK deficiency of approximately one case per 8 million population, slightly higher in Africans. Individuals with HK deficiency appeared asymptomatic and had decreased levels of prekallikrein and factor XI, which could lead to misdiagnosis.

CONCLUSION

HK deficiency is a rare condition with only few known pathogenic variants. It has an apparently good prognosis but is prone to misdiagnosis. Our understanding of its clinical implications is still limited, and an international prekallikrein and HK deficiency registry is being established to fill this knowledge gap.

The Coagulation Factors Fibrinogen, Thrombin, and Factor XII in Inflammatory Disorders-A Systematic Review

Background

The interaction of coagulation factors has been shown to go beyond their traditional roles in hemostasis and to affect the development of inflammatory diseases. Key molecular players, such as fibrinogen, thrombin, or factor XII have been mechanistically and epidemiologically linked to inflammatory disorders like multiple sclerosis (MS), rheumatoid arthritis (RA), and colitis.

Objectives

To systematically review the evidence for a role of coagulation factors, especially factor XII, fibrinogen, and thrombin in inflammatory disorders like MS, RA, and bowel disorders.

Methods

A systematic literature search was done in the PubMed database to identify studies about coagulation factors in inflammatory diseases. Original articles and reviews investigating the role of the kallikrein–kinin and the coagulation system in mouse and humans were included.

Results

We identified 43 animal studies dealing with inflammatory disorders and factors of the kallikrein–kinin or the coagulation system. Different immunological influences are described and novel molecular mechanisms linking coagulation and inflammation are reported.

Conclusion

A number of studies have highlighted coagulation factors to tip the balance between hemostasis and thrombosis and between protection from infection and extensive inflammation. To optimize the treatment of chronic inflammatory disorders by these factors, further studies are necessary.

Erosive arthritis and hepatic granuloma formation induced by peptidoglycan polysaccharide in rats is aggravated by prasugrel treatment

Administration of the thienopyridine P2Y12 receptor antagonist, clopidogrel, increased the erosive arthritis induced by peptidoglycan polysaccharide (PG-PS) in rats or by injection of the arthritogenic K/BxN serum in mice. To determine if the detrimental effects are caused exclusively by clopidogrel, we evaluated prasugrel, a third-generation thienopyridine pro-drug, that contrary to clopidogrel is mostly metabolized into its active metabolite in the intestine. Prasugrel effects were examined on the PG-PS-induced arthritis rat model. Erosive arthritis was induced in Lewis rats followed by treatment with prasugrel for 21 days. Prasugrel treated arthritic animals showed a significant increase in the inflammatory response, compared with untreated arthritic rats, in terms of augmented macroscopic joint diameter associated with significant signs of inflammation, histomorphometric measurements of the hind joints and elevated platelet number. Moreover, fibrosis at the pannus, assessed by immunofluorescence of connective tissue growth factor, was increased in arthritic rats treated with prasugrel. In addition to the arthritic manifestations, hepatomegaly, liver granulomas and giant cell formation were observed after PG-PS induction and even more after prasugrel exposure. Cytokine plasma levels of IL-1 beta, IL-6, MIP1 alpha, MCP1, IL-17 and RANTES were increased in arthritis-induced animals. IL-10 plasma levels were significantly decreased in animals treated with prasugrel. Overall, prasugrel enhances inflammation in joints and liver of this animal model. Since prasugrel metabolites inhibit neutrophil function ex-vivo and the effects of both clopidogrel and prasugrel metabolites on platelets are identical, we conclude that the thienopyridines metabolites might exert non-platelet effects on other immune cells to aggravate inflammation.

Clopidogrel, a P2Y12 receptor antagonist, potentiates the inflammatory response in a rat model of peptidoglycan polysaccharide-induced arthritis

The P2Y12 receptor plays a crucial role in the regulation of platelet activation by several agonists, which is irreversibly antagonized by the active metabolite of clopidogrel, a widely used anti-thrombotic drug. In this study, we investigated whether reduction of platelet reactivity leads to reduced inflammatory responses using a rat model of erosive arthritis. We evaluated the effect of clopidogrel on inflammation in Lewis rats in a peptidoglycan polysaccharide (PG-PS)-induced arthritis model with four groups of rats: 1) untreated, 2) clopidogrel-treated, 3) PG-PS-induced, and 4) PG-PS-induced and clopidogrel-treated. There were significant differences between the PG-PS+clopidogrel group when compared to the PG-PS group including: increased joint diameter and clinical manifestations of inflammation, elevated plasma levels of pro-inflammatory cytokines (IL-1 beta, interferon (IFN) gamma, and IL-6), an elevated neutrophil blood count and an increased circulating platelet count. Plasma levels of IL-10 were significantly lower in the PG-PS+clopidogrel group compared to the PG-PS group. Plasma levels of platelet factor 4 (PF4) were elevated in both the PG-PS and the PG-PS+clopidogrel groups, however PF4 levels showed no difference upon clopidogrel treatment, suggesting that the pro- inflammatory effect of clopidogrel may be due to its action on cells other than platelets. Histology indicated an increase in leukocyte infiltration at the inflammatory area of the joint, increased pannus formation, blood vessel proliferation, subsynovial fibrosis and cartilage erosion upon treatment with clopidogrel in PG-PS-induced arthritis animals. In summary, animals treated with clopidogrel showed a pro-inflammatory effect in the PG-PS-induced arthritis animal model, which might not be mediated by platelets. Elucidation of the mechanism of clopidogrel-induced cell responses is important to understand the role of the P2Y12 receptor in inflammation.

Interaction of high-molecular-weight kininogen with endothelial cell binding proteins suPAR, gC1qR and cytokeratin 1 determined by surface plasmon resonance (BiaCore)

The physiologic activation of the plasma kallikrein-kinin system requires the assembly of its constituents on a cell membrane. High- molecular-weight kininogen (HK) and cleaved HK (HKa) both interact with at least three endothelial cell binding proteins: urokinase plasminogen activator receptor (uPAR), globular C1q receptor (gC1qR,) and cytokeratin 1 (CK1). The affinity of HK and HKa for endothelial cells are KD=7-52 nM. The contribution of each protein is unknown. We examined the direct binding of HK and HKa to the soluble extracellular form of uPAR (suPAR), gC1qR and CK1 using surface plasmon resonance. Each binding protein linked to a CM-5 chip and the association, dissociation and KD (equilibrium constant) were measured. The interaction of HK and HKa with each binding protein was zinc-dependent. The affinity for HK and HKa was gC1qR>CK1>suPAR, indicating that gC1qR is dominant for binding. The affinity for HKa compared to HK was the same for gC1qR, 2.6-fold tighter for CK1 but 53-fold tighter for suPAR. Complex between binding proteins was only observed between gC1qR and CK1 indicating that a binary CK1-gC1qR complex can form independently of kininogen. Although suPAR has the weakest affinity of the three binding proteins, it is the only one that distinguished between HK and HKa. This finding indicates that uPAR may be a key membrane binding protein for differential binding and signalling between the cleaved and uncleaved forms of kininogen. The role of CK1 and gC1qR may be to initially bind HK to the membrane surface before productive cleavage to HKa.

Peptide hormone regulation of angiogenesis

It is now apparent that regulation of blood vessel growth contributes to the classical actions of hormones on development, growth, and reproduction. Endothelial cells are ideally positioned to respond to hormones, which act in concert with locally produced chemical mediators to regulate their growth, motility, function, and survival. Hormones affect angiogenesis either directly through actions on endothelial cells or indirectly by regulating proangiogenic factors like vascular endothelial growth factor. Importantly, the local microenvironment of endothelial cells can determine the outcome of hormone action on angiogenesis. Members of the growth hormone/prolactin/placental lactogen, the renin-angiotensin, and the kallikrein-kinin systems that exert stimulatory effects on angiogenesis can acquire antiangiogenic properties after undergoing proteolytic cleavage. In view of the opposing effects of hormonal fragments and precursor molecules, the regulation of the proteases responsible for specific protein cleavage represents an efficient mechanism for balancing angiogenesis. This review presents an overview of the actions on angiogenesis of the above-mentioned peptide hormonal families and addresses how specific proteolysis alters the final outcome of these actions in the context of health and disease.

Vitreous proteomic analysis of proliferative vitreoretinopathy

Proliferative vitreoretinopathy (PVR) is the most common cause of anatomic failure in retinal detachment surgery. To understand the molecular mechanisms, vitreous proteomes of patients with PVR were investigated by two-dimensional-nano-liquid chromatography coupled with tandem mass spectrometry. Vitreous samples of moderate PVR (grade B), and severe PVR (grade C or D) were aspirated during pars plana vitrectomy before infusion. In the current study, 129, 97 and 137 proteins were identified in vitreous of normal control, moderate and severe PVR, respectively. In PVR vitreous samples, complement components, serine proteinase inhibitors, and extracellular proteins were up-regulated or appeared, while normal cytoskeleton and metabolism proteins were down-regulated or disappeared. It was noteworthy that the proteins involved in transcription and translation regulation increased in vitreous with PVR. Among 102 PVR-specific proteins, kininogen 1 was specifically detected in both vitreous and the corresponding serum. Therefore, it can be concluded that PVR is a complicated pathology process with great amount of proteins involved in metabolism dysfunction, immune reactions, and cytoskeleton remolding. Kininogen 1 may be a candidate biomarker of PVR. Further investigations of these special proteins will provide additional targets for treatment or prevention of ocular proliferative diseases.

Cleavage of high-molecular-weight kininogen by elastase and tryptase is inhibited by ferritin

Ferritin is a protein principally known for its role in iron storage. We have previously shown that ferritin can bind high-molecular-weight kininogen (HK). Upon proteolytic cleavage by the protease kallikrein, HK releases the proinflammatory peptide bradykinin (BK) and other biologically active products, such as two-chain high-molecular-weight kininogen, HKa. At inflammatory sites, HK is oxidized, which renders it a poor substrate for kallikrein. However, oxidized HK remains a good substrate for elastase and tryptase, thereby providing an alternative cleavage mechanism for HK during inflammation. Here we report that ferritin can retard the cleavage of both native HK and oxidized HK by elastase and tryptase. Initial rates of cleavage were reduced 45-75% in the presence of ferritin. Ferritin is not a substrate for elastase or tryptase and does not interfere with the ability of either protease to digest a synthetic substrate, suggesting that ferritin may impede HK cleavage through direct interaction with HK. Immunoprecipitation and solid phase binding studies reveal that ferritin and HK bind directly with a Kd of 134 nM. To test whether ferritin regulates HK cleavage in vivo, we used THP-1 cells, a human monocyte/macrophage cell line that has been used to model pulmonary inflammatory cells. We observed that ferritin impedes the cleavage of HK by secretory proteases in stimulated macrophages. Furthermore, ferritin, HK, and elastase are all present in or on alveolar macrophages in a mouse model of pulmonary inflammation. Collectively, these results implicate ferritin in the modulation of HK cleavage at sites of inflammation.

Identification of lipopolysaccharide binding site on high molecular weight kininogen

Plasma kallikrein kinin system (KKS) activation along with its cellular receptors expression are increased after injury and in patients with septic shock, hypotensive bacteremia and rhesus monkey infected with Salmonella typhimurium. KKS signaling cascade is activated by activated factor XII (FXIIa, Hageman factor)- and prolylcarboxypeptidase (PRCP)-dependent pathways on endothelial cells. Among the many entities that comprise the KKS, high molecular weight kininogen (HK), a bradykinin precursor, is critical in the assembly and activation of this system. HK is primarily expressed in the liver and secreted into the bloodstream. The activation of the KKS influences the permeability of the endothelium by liberating bradykinin (BK) from HK. BK is a potent inflammatory peptide which stimulates constitutive bradykinin B2 and inducible B1 receptors to release nitric oxide and prostacyclin. Regardless of the triggers, PK can only be activated on HK bound to the artificial negatively charged or to cell membrane surfaces. Since LPS has a negatively charged moiety and the ability to induce inflammatory responses in human, we determined the interaction between LPS and HK. HKH19 (HK cell binding site) and heparin inhibited LPS binding to HK with IC(50)s of 15nM and 20 microg/ml, respectively. C1-inhibitor and N-acetylglucosamine glycan inhibited LPS binding to HK with IC(50)s of about 10 microg/ml and 10mM, respectively. This novel study underscores the implication of HK in infection. We propose that HKH19, heparin, and C1-inhibitor present therapeutic potential for the treatment of sepsis and hypotensive bacteremia.

The alterations of mouse plasma proteins during septic development

A fundamental issue for sepsis therapy is to control the development of inflammation at an early stage. With cecal ligation and puncture (CLP) surgery, the mouse model has clearly shown the septic signs triggered by chronic insult. To monitor the plasma proteomic responses to sepsis, the mouse blood was collected at intervals after sham and CLP surgery followed by the sample treatment to remove high abundance serum albumin. The treated mouse plasma proteins were well resolved by two-dimensional electrophoresis (2-DE). The image analysis revealed that these 2-DE spots observed from the sham and the CLP samples 4 h after surgery were comparable, whereas more than 30 different spots appeared on the 2-DE gels between the sham and CLP mouse plasma 24 h after surgery, indicating that some plasma proteins responded to the inflammatory development. These differential spots were verified by MALDI-TOF/TOF MS, resulting in 13 unique sepsis-responsive proteins. More importantly, most of them exhibited multiple spots as difference on the 2-DE gels. Furthermore, these isospots were incubated with PNGase F to eliminate N-linked oligosaccharides on proteins and then evaluated by Western blot as well as mass spectrometry. The results of PNGase F digestion suggested that most sepsis-associated proteins remained in N-glycosylation status but changed their N-glycans during septic development.

Regulators of angiogenesis and strategies for their therapeutic manipulation

Angiogenesis provides a mechanism by which delivery of oxygen and nutrients is adapted to compliment changes in tissue mass or metabolic activity. However, maladaptive angiogenesis is integral to the process of several diseases common in Western countries, including tumor growth, vascular insufficiency, diabetic retinopathy and rheumatoid arthritis. Understanding the process of capillary growth, including the identification and functional analyses of key pro- and anti-angiogenic factors, provides knowledge that can be applied to improve/reverse these pathological states. Initially, angiogenesis research focused predominantly on vascular endothelial growth factor (VEGF) as a main player in the angiogenesis cascade. It is apparent now that participation of multiple angiogenic factors and signal pathways is critical to enable effective growth and maturation of nascent capillaries. The purpose of this review is to focus on recent progress in identifying angiogenesis signaling pathways that show promise as targets for successful induction or inhibition of capillary growth. The strategies applied to achieve these contradictory tasks are discussed within the framework of our existing fundamental knowledge of angiogenesis signaling cascades, with an emphasis on comparing the employment of distinctive tactics in modulation of these pathways. Innovative developments that are presented include: (1) inducing a pleiotropic response via activation or inhibition of angiogenic transcription factors; (2) modulation of nitric oxide tissue concentration; (3) manipulating the kallikrein-kinin system; (4) use of endothelial progenitor cells as a means to either directly contribute to capillary growth or to be used as a vehicle to deliver "suicide genes" to tumor tissue.

Role of cystatins in tumor neovascularization

Cystatins form a large superfamily of proteins with diverse biologic activities. All members of the cystatin superfamily share the presence of one, two or three cystatin domains. Cystatins were initially believed to act mainly as inhibitors of lysosomal cysteine proteases. In recent years, however, there has been increased awareness of additional or alternate biologic functions for these proteins. In this review, the authors will discuss the most recent findings and hypotheses that suggest that some members of the cystatin superfamily may play important roles during tumor progression. Special emphasis is given to their potential role as novel anti-angiogenic agents.

Modulation of inflammation by kininogen deficiency in a rat model of inflammatory arthritis

OBJECTIVE

To compare inflammatory peripheral arthritis in wild-type and high molecular weight kininogen (HK)-deficient rats, both on the genetically susceptible Lewis background.

METHODS

By backcrossing Brown-Norway HK-deficient rats with Lewis rats for 6 generations, 2 new strains were produced, wild-type F6 and HK-deficient F6, each with a 98.5% Lewis genome. Inflammatory arthritis was induced by intraperitoneal injection of peptidoglycan-polysaccharide (PG-PS), and the clinical, histopathologic, and biochemical responses were compared in both strains.

RESULTS

Eighteen days after PG-PS injection, rats with normal concentrations of HK showed weight loss and marked increase in hind ankle diameter with severe synovial inflammation and cartilage abnormalities. In contrast, HK-deficient rats showed no weight loss (P < 0.05), no increase in hind ankle diameter (P < 0.05), and an absence of inflammatory changes (P < 0.05), as measured by the histologic and morphometric Mankin grading system for synovial and cartilage injury.

CONCLUSION

Plasma HK is a key mediator of acute and chronic inflammatory arthritis in genetically susceptible Lewis rats.

Recent advances in reactive arthritis

Reactive arthritis (ReA), one of the spondyloarthropathies, is an infectious related disease that occurs in a genetically predisposed individual, characterized by an immune-mediated synovitis with intra-articular persistence of viable nonculturable bacteria and/or immunogenic bacterial antigens. ReA long term prognosis is not as good as it was earlier believed. Two-thirds of patients develop prolonged joint discomfort, low back pain, or enthesopathies after acute ReA, and 15% to 30% of them develop chronic symptoms. The therapeutic options for patients with the more severe forms of the disease have been rather limited. The efficacy of tumor necrosis factor antagonists in other spondyloarthritis suggested that anticytokine therapy could also be effective for ReA. This paper reviews the latest concepts in urogenital and postenteric human leukocyte antigen-B27-associated ReA.

A monoclonal antibody against kininogen reduces inflammation in the HLA-B27 transgenic rat

The human leukocyte antigen B27 (HLA-B27) transgenic rat is a model of human inflammatory bowel disease, rheumatoid arthritis and psoriasis. Studies of chronic inflammation in other rat models have demonstrated activation of the kallikrein–kinin system as well as modulation by a plasma kallikrein inhibitor initiated before the onset of clinicopathologic changes or a deficiency in high-molecular-mass kininogen. Here we study the effects of monoclonal antibody C11C1, an antibody against high-molecular-mass kininogen that inhibits the binding of high-molecular-mass kininogen to leukocytes and endothelial cells in the HLA-B27 rat, which was administered after the onset of the inflammatory changes. Thrice-weekly intraperitoneal injections of monoclonal antibody C11C1 or isotype IgG₁ were given to male 23-week-old rats for 16 days. Stool character as a measure of intestinal inflammation, and the rear limbs for clinical signs of arthritis (tarsal joint swelling and erythema) were scored daily. The animals were killed and the histology sections were assigned a numerical score for colonic inflammation, synovitis, and cartilage damage. Administration of monoclonal C11C1 rapidly decreased the clinical scores of pre-existing inflammatory bowel disease (P < 0.005) and arthritis (P < 0.001). Histological analyses confirmed significant reductions in colonic lesions (P = 0.004) and synovitis (P = 0.009). Decreased concentrations of plasma prekallikrein and high-molecular-mass kininogen were found, providing evidence of activation of the kallikrein–kinin system. The levels of these biomarkers were reversed by monoclonal antibody C11C1, which may have therapeutic potential in human inflammatory bowel disease and arthritis.

Two faces of high-molecular-weight kininogen (HK) in angiogenesis: bradykinin turns it on and cleaved HK (HKa) turns it off

High-molecular-weight kininogen (HK) is a plasma protein that possesses multiple physiological functions. Originally identified as a precursor of bradykinin, a bioactive peptide that regulates many cardiovascular processes, it is now recognized that HK plays important roles in fibrinolysis, thrombosis, and inflammation. HK binds to endothelial cells where it can be cleaved by plasma kallikrein to release bradykinin (BK). The remaining portion of the molecule, cleaved HK, is designated cleaved high-molecular-weight kininogen or HKa. While BK has been intensively studied, the physiological implication of the generation of HKa is not clear. Recent studies have revealed that HKa inhibits angiogenesis while BK promotes angiogenesis. These findings represent novel functions of the kallikrein-kinin system that have not yet been fully appreciated. In this review, we will briefly discuss the recent progress in the studies of the molecular mechanisms that mediate the antiangiogenic effect of HKa and the proangiogenic activity of BK.