Development and immunochemical evaluation of a novel chicken IgY antibody specific for KLK6

Anti-SpCas9 IgY Polyclonal Antibodies Production for CRISPR Research Use

The CRISPR/Cas adaptative immune system has been harnessed as an RNA-guided, programmable genome editing tool, allowing for diverse biotechnological applications. The implementation of the system relies on the ability to detect the Cas9 protein in biological samples. This task is facilitated by employing antibodies, which exhibit several advantageous features and applications in the context of tropical neglected diseases. This study reports a one-month immunization scheme with the Cas9 protein fromStreptococcus pyogenes to produce IgY polyclonal antibodies (anti-SpCas9), which can be rapidly isolated by combining yolk de-lipidation with protein salting out using pectin and ammonium sulfate, respectively. Immunodetection assays indicate that the antibodies are highly sensitive, specific, and useful for detecting the SpCas9 protein in promastigotes ofLeishmania braziliensisexpressing exogenous SpCas9. Thus, the simple method for producing anti-SpCas9 IgY antibodies will accelerate CRISPR/Cas-based studies in Leishmania spp. This approach serves as a valuable research tool in this parasite model and holds the potential for wide application in various other biological samples, promoting the implementation of the system. In fact, a bioinformatics approach based on the identification of antigenic determinants in the SpCas9 protein suggests the possibility of using the anti-SpCas9 IgY antibodies in applications such as Prime and Base editing.

IgY technology: Methods for developing and evaluating avian immunoglobulins for the in vitro detection of biomolecules

The term “IgY technology” was introduced in the literature in the mid 1990s to describe a procedure involving immunization of avian species, mainly laying hens and consequent isolation of the polyclonal IgYs from the “immune” egg yolk (thus avoiding bleeding and animal stress). IgYs have been applied to various fields of medicine and biotechnology. The present article will deal with specific aspects of IgY technology, focusing on the currently reported methods for developing, isolating, evaluating and storing polyclonal IgYs. Other topics such as current information on isolation protocols or evaluation of IgYs from different avian species are also discussed. Specific advantages of IgY technology (e.g., novel antibody specificities that may emerge via the avian immune system) will also be discussed. Recent in vitro applications of polyclonal egg yolk-derived IgYs to the field of disease diagnosis in human and veterinary medicine through in vitro immunodetection of target biomolecules will be presented. Moreover, ethical aspects associated with animal well-being as well as new promising approaches that are relevant to the original IgY technology (e.g., development of monoclonal IgYs and IgY-like antibodies through the phage display technique or in transgenic chickens) and future prospects in the area will also be mentioned.

A proinflammatory role of KLK6 protease in Netherton syndrome

BACKGROUND

Netherton syndrome (NS) is a rare but severe type of ichthyosis characterized by atopy, allergies, and potentially lethal skin overdesquamation associated with highly elevated proteolytic activities in LEKTI-deficient epidermis. NS symptoms are recapitulated in Spink5^-/- mouse where the gene encoding Lekti has been invalidated. Spink5^-/- mice die within 5h from birth due to their severe skin barrier defect leading to dehydration. Spink5^-/- mice also serve as a model for atopic dermatitis. The KLK6 protease is expressed by epidermal keratinocytes and shown in vitro to cleave desmosomal components.

OBJECTIVE

To investigate in vivo whether KLK6 is implicated in epidermal overdesquamation and/or inflammation associated with NS.

METHODS

The role of KLK6 was evaluated by generating Spink5^-/-Klk6^-/- double knockout mice. The phenotype was assessed by macroscopic observation, immunohistochemistry for differentiation markers, in situ zymography for proteolysis, and quantification of proinflammatory cytokines.

RESULTS

Elimination of Klk6 in Spink5^-/- remarkably suppresses the expression of Tslp, a major itching-inducing factor and driver of allergic reactions. Tnfα and the Th17 promoting cytokine Il-23 were also suppressed. Spink5^-/-Klk6^-/- mice display normalized keratinocyte differentiation, nevertheless, epidermal proteolytic activities and the associated overdesquamation were not ameliorated, and Spink5^-/-Klk6^-/- still died from a severe epidermal barrier defect as the Spink5^-/-.

CONCLUSIONS

Ablation of Klk6 largely suppresses epidermal inflammation but cannot rescue overdesquamation leading to the lethal NS phenotype. Nonetheless, our findings demonstrate for the first time that KLK6 is implicated in skin inflammation and may represent a novel druggable target for NS and other inflammatory conditions e.g. atopic dermatitis.

Preparation and Application of Egg Yolk Antibodies Against Chinese Sacbrood Virus Infection

Chinese sacbrood virus (CSBV) infects Apis cerana larvae, resulting in the inability of the larvae to pupate and their consequent death, which may pose a serious threat to entire colonies. As there is no effective medical treatment for CSBV infections, further studies are necessary. In this study, an effective treatment for CSBV is described, based on a specific immunoglobulin Y (IgY) from egg yolk against CSBV. The inactivated vaccine was produced by ultracentrifugation and formalin treatment, using CSBV purified from a natural outbreak. The specific IgY was produced by immunization of white leghorn hens with the vaccine. An enzyme-linked immunosorbent assay using purified CSBV as the coating antigen revealed that the anti-CSBV IgY titer began increasing in the egg yolk on the 14th day post-immunization, reaching a peak on day 42, and anti-CSBV IgY remained at a high level until day 91. IgY isolated from the combinations of egg yolk collected between days 42-91 was purified by PEG and ammonium sulfate precipitation. In three repeated protection experiments using A. cerana larvae inoculated with CSBV, the survival rate of larvae was more than 80%, and the titer of anti-CSBV IgY was more than 25 and 24 when the larvae were fed IgY 24 h after and before inoculation with CSBV, respectively. Therefore, 400 colonies infected with CSBV were treated by feeding sugar containing IgY solutions with an antibody titer of 25, and the cure rate was 95-100%. Three hundred susceptible colonies were protected by feeding the larvae with sugar containing IgY solutions with an antibody titer of 24, and the protection rate was 97%. The results clearly suggest that a specific IgY was obtained from hens immunized with an inactivated-CSBV vaccine; this may be a novel method for controlling CSBV infection.

Development of Adenosine Deaminase-Specific IgY Antibodies: Diagnostic and Inhibitory Application

Adenosine deaminase (ADA) is currently used as a diagnostic marker for tuberculous pleuritis. Although ADA has been suggested as a potential marker for several types of cancer, the importance of each of ADA isoforms as well as their levels and enzymatic activities in tumors need to be further investigated. Herein we developed avian immunoglobulin Y highly specific to human ADA via hens immunization with calf adenosine deaminase. The obtained antibodies were used for the development of a sensitive double-egg yolk immunoglobulin (IgY) sandwich ELISA assay with an ADA detection limit of 0.5 ng/ml and a linearity range of up to 10 ng/ml. Specific, affinity-purified IgYs were able to recognize human recombinant ADA and ADA present in human cancer cell lines. In addition, antigen-specific IgY antibodies were able to inhibit catalytic activity of calf ADA with an IC₅₀ value of 47.48 nM. We showed that generated IgY antibodies may be useful for ADA detection, thus acting as a diagnostic agent in immunoenzymatic assays.

KLK6 proteolysis is implicated in the turnover and uptake of extracellular alpha-synuclein species

KLK6 is a serine protease highly expressed in the nervous system. In synucleinopathies, including Parkinson disease, the levels of KLK6 inversely correlate with α-synuclein in CSF. Recently, we suggested that recombinant KLK6 mediates the degradation of extracellular α-synuclein directly and via a proteolytic cascade that involves unidentified metalloproteinase(s). Here, we show that recombinant and naturally secreted KLK6 can readily cleave α-synuclein fibrils that have the potential for cell-to-cell propagation in “a prion-like mechanism”. Importantly, KLK6-deficient primary cortical neurons have increased ability for α-synuclein fibril uptake. We also demonstrate that KLK6 activates proMMP2, which in turn can cleave α-synuclein. The repertoire of proteases activated by KLK6 in a neuronal environment was analyzed by degradomic profiling, which also identified ADAMTS19 and showed that KLK6 has a limited number of substrates indicating specific biological functions such as the regulation of α-synuclein turnover. We generated adenoviral vectors for KLK6 delivery and demonstrated that the levels of extracellular α-synuclein can be reduced by neuronally secreted KLK6. Our findings open the possibility to exploit KLK6 as a novel therapeutic target for Parkinson disease and other synucleinopathies.

Kallikreins - The melting pot of activity and function

The human tissue kallikrein and kallikrein-related peptidases (KLKs), encoded by the largest contiguous cluster of protease genes in the human genome, are secreted serine proteases with diverse expression patterns and physiological roles. Because of the broad spectrum of processes that are modulated by kallikreins, these proteases are the subject of extensive investigations. This review brings together basic information about the biochemical properties affecting enzymatic activity, with highlights on post-translational modifications, especially glycosylation. Additionally, we present the current state of knowledge regarding the physiological functions of KLKs in major human organs and outline recent discoveries pertinent to the involvement of kallikreins in cell signaling and in viral infections. Despite the current depth of knowledge of these enzymes, many questions regarding the roles of kallikreins in health and disease remain unanswered.

Generation and application of polyclonal IgY antibodies specific for full-length and nicked prostate-specific antigen.Bioanalysis. 2014;6:3197-3213. [PMID: 25529887 DOI: 10.4155/bio.14.172]

BACKGROUND

The prostate-specific antigen (PSA) is considered an important serum marker for prostate cancer detection, monitoring and staging. The purpose of this study was to generate IgY class antibodies that recognize native PSA and selected epitopes.

METHODOLOGY

Hens immunized with either full-length human PSA or its peptidyl fragment-conjugates produced specific antibodies that were isolated from egg yolks. We developed a monoclonal/IgY sandwich ELISA with a PSA detection limit of 50 pg/ml and a linear range of 0.05-1.0 ng/ml.

CONCLUSION

Because the signal observed for the PSA-specific IgY antibodies by ELISA and the reactivity profile of the epitope-derived IgYs were comparable to those of mouse monoclonal IgG antibodies, avian antibodies may be a cost-effective alternative to mammalian antibodies for prostate cancer diagnostics.

Adjuvant-dependent immunogenicity of Staphylococcus aureus Efb and Map proteins in chickens

The avian IgY antibodies generated in hens and isolated from egg yolk have gained in popularity as they present an alternative source of antibodies for diagnostic as well as therapeutic applications. One of the advantages of IgY technology are the large amounts of produced antibodies from a single animal combined with their high reactivity representing an attractive alternative for mammalian antibodies. Despite many known protocols for the immunization of chickens, the administration of new antigens often requires additional modification such as antigen dose or use of an adjuvant in order to elicit a significant immune response. We investigated the immunogenicity of three Staphylococcus aureus antigens including two extracellular proteins Map and Efb and one selected Efb105-124 epitope conjugated to KLH that were administered to the animals. Additionally, the immunization protocol included two adjuvant systems: Freund's complete adjuvant and Emulsigen-D. The results demonstrated a high immunostimulatory potency of Freund's complete adjuvant, especially in case of Efb compared to the immune response elicited by Emulsigen-D. However, after immunization with the KLH-Efb105-124 conjugate, the obtained antibodies showed similar reactivity regardless of adjuvant system used with the only exception being their avidity.