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Discover how PEPperPRINT Peptide Microarray products have been used in different fields of research.

A quantitative and site-specific atlas of the citrullinome reveals widespread existence of citrullination and insights into PADI4 substrates

Rebak, Alexandra S.; Hendriks, Ivo A.; Elsborg, Jonas D.; Buch-Larsen, Sara C.; Nielsen, Claus H.; Terslev, Lene; Kirsch, Rebecca; Damgaard, Dres; Doncheva, Nadezhda T.; Lennartsson, Caroline; Rykær, Martin; Jensen, Lars J.; Christophorou, Maria A.; Nielsen, Michael L.
Nat Struct Mol Biol.
Feb 2024
Abstract Despite the importance of citrullination in physiology and disease, global identification of citrullinated proteins, and the precise targeted sites, has remained challenging. Here we employed quantitative-mass-spectrometry-based proteomics to generate a comprehensive atlas of citrullination sites within the HL60 leukemia cell line following differentiation into neutrophil-like cells. We identified 14,056 citrullination sites within 4,008 proteins and quantified their regulation upon inhibition of the citrullinating enzyme PADI4. With this resource, we provide quantitative and site-specific information on thousands of PADI4 substrates, including signature histone marks and transcriptional regulators. Additionally, using peptide microarrays, we demonstrate the potential clinical relevance of certain identified sites, through distinct reactivities of antibodies contained in synovial fluid from anti-CCP-positive and anti-CCP-negative people with rheumatoid arthritis. Collectively, we describe the human citrullinome at a systems-wide level, provide a resource for understanding citrullination at the mechanistic level and link the identified targeted sites to rheumatoid arthritis.

ASFV epitope mapping by high density peptides microarrays

Desmet, Cloé; Coelho-Cruz, Bruna; Mehn, Dora; Colpo, Pascal; Ruiz-Moreno, Ana
Virus Research.
Jan 2024
African swine fever (ASF) is an acute, highly contagious and deadly infectious disease. It is a threat to animal health with major potential economic and societal impact. Despite decades of ASF vaccine research, still some gaps in knowledge are hindering the development of a functional vaccine. Worth mentioning are gaps in understanding the mechanism of ASF infection and immunity, as well as the fact that – in case of this disease – virus proteins, so-called protective antigens, responsible for inducing protective immune responses in pigs are not identified yet. In this paper we elaborate on a methodology to identify protective antigens based on epitope mapping by microarray technology. High density peptide microarrays, combined with fluorescence scanning, have been used to analyze the interaction of peptide sequences of African swine fever virus (ASFV) proteins with antibodies present in inactivated serum from infected and healthy animals. The study evidenced ASFV proteins already under the radar for vaccine development, such as p54, and identified specific sequences in those proteins that may become the focus for future vaccine candidates. Such methodology is amenable to automation and high-throughput and may help developing better targeting for next generation vaccines.

Immunity to Influenza is dependent on MHC II polymorphism: study with 2 HLA transgenic strains

Luckey, David; Weaver, Eric A.; Osborne, Douglas G.; Billadeau, Daniel D.; Taneja, Veena
Sci Rep.
Dec 2019
Major histocompatibility complex II (MHC II) molecules are involved in antigen presentation and the development of a functional adaptive immune response. Evolutionary selection for MHC molecules that effectively clear infectious agents provides an advantage to humans. However, certain class II molecules are associated with autoimmune diseases. In this study we infected autoimmune-susceptible DRB1*0401.AEo and non-susceptible *0402.AEo mice with H1N1 influenza and determined clearance and protective immunity to H3N2 virus. *0401 mice generated a robust TLR-triggered immune response and cleared H1N1 influenza virus infection. After vaccination and challenge with H1N1, *0401 mice, when challenged with H3N2, generated cross-protective immunity to heterosubtypic H3N2 influenza strain whereas *0402 mice cleared the H1N1 infection but did not generate cross-protective immunity against the H3N2 influenza strain. The intracellular trafficking route of MHCII revealed that *0401 molecules traffic through the late endosome/lysosomes while *0402 molecules traffic into early endosomes. This suggested that trafficking of MHCII could affect the functional output of the innate immune response and clearance of viral infections. Also, DRB1*0401 mice live longer than HLA-DRB1*0402 mice. The study provides a potential hypothesis for evolutionary selection of *0401 molecule, even though it is associated with autoreactivity, which may be dependent on the availability of peptide repertoire of self-antigens.

Analysis of humoral immune responses in chikungunya virus (CHIKV) infected patients and individuals vaccinated with a candidate CHIKV vaccine

Henss, Lisa; Yue, Constanze; von Rhein, Christine; Tschismarov, Roland; Lewis-Ximenez, Lia Laura; Dölle, Albert; Baylis, Sally A; Schnierle, Barbara S
Abstract Background Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that causes severe flu like symptoms. The acute symptoms disappear after one week, but chronic arthralgia can persist for years. Here, humoral immune responses in CHIKV-infected patients and vaccinees were analyzed. Methods Alphavirus neutralization activity was analyzed with pseudotyped lentiviral vectors and antibody epitope mapping was performed with a peptide array. Results Greatest CHIKV neutralization activity was observed 60-92 days after onset of symptoms. The amount of CHIKV-specific antibodies, their binding avidity and cross-reactivity with other alphaviruses increased over time. CHIKV and o’nyong-nyong virus (ONNV) were both neutralized to a similar extent. Linear antibody binding epitopes were mainly found in E2 domain B and the acid-sensitive regions (ASRs). In addition, serum samples from healthy volunteers vaccinated with a measles-vectored chikungunya vaccine candidate, MV-CHIK, were analyzed. Neutralization activity in the samples from the vaccine cohort was 2–6-fold lower than in samples from CHIKV-infected patients. In contrast to infection, vaccination only induced cross-neutralization with ONNV and the E2 ASR1 was the major antibody target. Conclusion These data could assist vaccine design and enable the identification of correlates of protection necessary for vaccine efficacy.

Probing peptide sequences on their ability to generate affinity sites in molecularly imprinted polymers

Piletska, Elena V; Guerreiro, Antonio; Mersiyanova, Margarita; Cowen, Todd; Canfarotta, Francesco; Piletsky, Stanislav S.; Karim, Kal; Piletsky, Sergey A.
Langmuir.
Dec 2019
An array of 4000 defined and addressable tripeptides on a polymer-coated glass slide is used to synthesize molecularly imprinted polymer (MIP) nanoparticles. This work is undertaken to systematically probe the impact of the peptide sequence on the ability to generate affinity MIPs. The polymer affinity is assessed by measuring the fluorescence of bound MIP nanoparticles at each peptide spot on the surface after washing the array to remove any low-affinity polymer. The generic composition commonly used in the preparation of MIPs against proteins seems to be equally suitable for imprinting hydrophobic and hydrophilic tripeptides. The amino acids frequently contributing to the formation of high-affinity MIPs include T, F, D, N, Y, W, and P. The amino acids that rarely contribute to the formation of high-affinity interactions with MIPs are G, V, A, L, I, and M. These observations are confirmed by computational modeling. The basic technique proposed here may be applicable in optimizing polymer compositions for the production of high-affinity MIPs or, more specifically, for the selection of appropriate amino acid sequences when peptide epitopes are used instead of whole protein imprinting.

α-Synuclein Penetrates Mucin Hydrogels Despite Its Mucoadhesive Properties

Marczynski, Matthias; Rickert, Carolin A.; Semerdzhiev, Slav A.; van Dijk, Wouter R.; Segers-Nolten, Ine M. J.; Claessens, Mireille M. A. E.; Lieleg, Oliver
Biomacromolecules.
Dec 2019
Recent research indicates that the progression of Parkinson’s disease can start from neurons of the enteric nervous system, which are in close contact with the gastrointestinal epithelium: α-synuclein molecules can be transferred from these epithelial cells in a prion-like fashion to enteric neurons. Thin mucus layers constitute a defense line against the exposure of noninfected cells to potentially harmful α-synuclein species. We show that—despite its mucoadhesive properties—α-synuclein can translocate across mucin hydrogels, and this process is accompanied by structural rearrangements of the mucin molecules within the gel. Penetration experiments with different α-synuclein variants and synthetic peptides suggest that two binding sites on α-synuclein are required to accomplish this rearrangement of the mucin matrix. Our results support the notion that the translocation of α-synuclein across mucus barriers observed here might be a critical step in the infection of the gastrointestinal epithelium and the development of Parkinson’s disease.

Peptides of neuron specific enolase as potential ASD biomarkers: From discovery to epitope mapping

Ramirez-Celis, Alexandra; Edmiston, Elizabeth; Schauer, Joseph; Vu, Tam; Van de Water, Judy
Brain, Behavior, and Immunity.
Dec 2019
Autism spectrum disorder (ASD) is an important health issue and affects 1 in 59 children in the US. Prior studies determined that maternal autoantibody related (MAR) autism is thought to be associated with ~23% of ASD cases. We previously identified seven MAR-specific autoantigens including CRMP1, CRMP2, GDA, LDHA, LDHB, STIP1, and YBX1. We subsequently described the epitope peptide sequences recognized by maternal autoantibodies for each of the seven ASD-specific autoantigens. The aim of the current study was to expand upon our previous work and identify additional antigens recognized by the ASD-specific maternal autoantibodies, as well as to map the unique ASD-specific epitopes using microarray technology. Fetal Rhesus macaque brain tissues were separated by molecular weight and a fraction containing bands between 37 and 45 kDa was analyzed using 2-D gel electrophoresis, followed by peptide mass mapping using MALDI-TOF MS and TOF/TOF tandem MS/MS. Using this methodology, Neuron specific enolase (NSE) was identified as a target autoantigen and selected for epitope mapping. The full NSE sequence was translated into 15-mer peptides with an overlap of 14 amino acids onto microarray slides and probed with maternal plasma from mothers with an ASD child and from mothers with a Typically Developing child (TD) (ASD = 27 and TD = 21). The resulting data were analyzed by T-test. We found 16 ASD-specific NSE-peptide sequences for which four sequences were statistically significant (p < 0.05) using both the t-test and SAM t-test: DVAASEFYRDGKYDL (p = 0.047; SAM score 1.49), IEDPFDQDDWAAWSK (p = 0.049; SAM score 1.49), ERLAKYNQLMRIEEE (p = 0.045; SAM score 1.57), and RLAKYNQLMRIEEEL (p = 0.017; SAM score 1.82). We further identified 5 sequences that were recognized by both ASD and TD antibodies suggesting a large immunodominant epitope (DYPVVSIEDPFDQDDWAAW). While maternal autoantibodies against the NSE protein are present both in mothers with ASD and mothers of TD children, there are several ASD-specific epitopes that can potentially be used as MAR ASD biomarkers. Further, studies including analysis of NSE as a target protein in combination with the previously identified MAR ASD autoantigens are currently underway.

Diagnostic Profiling of the Human Public IgM Repertoire With Scalable Mimotope Libraries

Pashov, Anastas; Shivarov, Velizar; Hadzhieva, Maya; Kostov, Victor; Ferdinandov, Dilyan; Heintz, Karen-Marie; Pashova, Shina; Todorova, Milena; Vassilev, Tchavdar; Kieber-Emmons, Thomas; Meza-Zepeda, Leonardo A.; Hovig, Eivind
Front. Immunol..
Dec 2019
Specific antibody reactivities are routinely used as biomarkers, but the antibody repertoire reactivity (igome) profiles are still neglected. Here, we propose rationally designed peptide arrays as efficient probes for these system level biomarkers. Most IgM antibodies are characterized by few somatic mutations, polyspecificity, and physiological autoreactivity with housekeeping function. Previously, probing this repertoire with a set of immunodominant self-proteins provided a coarse analysis of the respective repertoire profiles. In contrast, here, we describe the generation of a peptide mimotope library that reflects the common IgM repertoire of 10,000 healthy donors. In addition, an appropriately sized subset of this quasi-complete mimotope library was further designed as a potential diagnostic tool. A 7-mer random peptide phage display library was panned on pooled human IgM. Next-generation sequencing of the selected phage yielded 224,087 sequences, which clustered in 790 sequence clusters. A set of 594 mimotopes, representative of the most significant sequence clusters, was shown to probe symmetrically the space of IgM reactivities in patients’ sera. This set of mimotopes can be easily scaled including a greater proportion of the mimotope library. The trade-off between the array size and the resolution can be explored while preserving the symmetric sampling of the mimotope sequence and reactivity spaces. BLAST search of the non-redundant protein database with the mimotopes sequences yielded significantly more immunoglobulin J region hits than random peptides, indicating a considerable idiotypic connectivity of the targeted igome. The proof of principle predictors for random diagnoses was represented by profiles of mimotopes. The number of potential reactivity profiles that can be extracted from this library is estimated at more than 1070. Thus, a quasi-complete IgM mimotope library and a scalable representative subset thereof are found to address very efficiently the dynamic diversity of the human public IgM repertoire, providing informationally dense and structurally interpretable IgM reactivity profiles.

Ara h 7 isoforms share many linear epitopes: Are 3D epitopes crucial to elucidate divergent abilities?

Ehlers, Anna M.; Klinge, Marco; Suer, Waltraud; Weimann, Yvonne; Knulst, André C.; Besa, Frithjof; Le, Thuy‐My; Otten, Henny G.
Clin Exp Allergy.
Nov 2019
Background The peanut allergens Ara h 2, h 6, and h 7 are potent allergens and can trigger severe reactions. Ara h 7 consists of three isoforms differing in their ability to induce basophil degranulation, whereas the ability of Ara h 7.0201 is comparable to Ara h 2 and 6 as shown in previous literature. Objective To identify linear epitopes of Ara h 7.0101, Ara h 7.0201 and Ara h 7.0301 recognized by IgE and IgG4 from patients sensitized to Ara h 7 and to investigate their potential to elucidate divergent abilities of the Ara h 7 isoforms in inducing basophil activation. Methods Linear epitopes recognized by IgE and IgG4 were mapped by peptide microarray analysis containing 15-mer peptides of Ara h 2.0201, 6, 7.0101, 7.0201 and 7.0301 and 39 peanut allergic patients sensitized to Ara h 7 (discovery). For validation, 20-mer peptides containing the minimal epitope and surrounding amino acids were incubated with 25 sensitized patients and 10 controls (validation). Results Three out of 14 linear epitopes were unique for each isoform (Ara h 7.0101: aa 97-109; Ara h 7.0201: aa 122-133; Ara h 7.0301: aa 65-74) but scarcely recognized by IgE. The main linear IgE epitope (aa 51-57) located in the long flexible loop of all Ara h 7 isoforms was bound by antibodies from 31% of the patients (discovery and validation cohort). Regarding IgG4, 55% of the patients recognized an epitope present on all isoforms (aa 55-65), whereas epitope aa 129-137, only present on Ara h 7.0101/0.0301, was recognized by 38% of the patients. Recognition was highly individual, although 20% of the patients recognized any linear epitope neither by IgE nor by IgG4 despite a low mean z-score of ≥ 1.7. Remarkably, only 50% of the patients recognized one or more epitopes by IgE. Conclusion & Clinical Relevance Ara h 7 isoforms share many linear epitopes being easily accessible for antibody binding. Unique epitopes, essential to elucidate divergent potencies, were scarcely recognized, suggesting a crucial involvement of conformational epitopes.

A Low‐Cost Laser‐Based Nano‐3D Polymer Printer for Rapid Surface Patterning and Chemical Synthesis of Peptide and Glycan Microarrays

Eickelmann, Stephan; Tsouka, Alexandra; Heidepriem, Jasmin; Paris, Grigori; Zhang, Junfang; Molinari, Valerio; Mende, Marco; Loeffler, Felix F.
Adv. Mater. Technol..
Nov 2019
A low-cost laser-based printing setup is presented, which allows for the spot-wise patterning of surfaces with defined polymer nanolayers. These nanolayer spots serve as a “solid solvent,” embedding different chemicals, chemical building blocks, materials, or precursors and can be stacked on top of each other. By melting the spot pattern, the polymer-embedded molecules are released for chemical reaction. This enables researchers to quickly pattern a surface with different molecules and materials, mixing them directly on the surface for high-throughput chemical synthesis to generate and screen diverse microarray libraries. In contrast to expensive ink-jet or contact printing, this approach does not require premixing of inks, which enables in situ combinatorial mixing. Easy access and versatility of this patterning approach are shown by generating microarrays of various biomolecules, such as glycans for the first time, to screen interactions of antibodies and lectins. In addition, a layer-by-layer solid-phase synthesis of peptides directly on the microarray is presented. Amino acid–containing nanolayers are repeatedly laser-transferred and reacted with the functionalized acceptor surface in defined patterns. This simple system enables a reproducible array production, down to spot-to-spot distances of 100 µm, and offers a flexible and cheap alternative to expensive spotting robot technology.

Predicting HBsAg clearance in genotype A chronic hepatitis B using HBsAg epitope profiling: A biomarker for functional cure

Walsh, Renae; Hammond, Rachel; Yuen, Lilly; Deerain, Joshua; O’Donnell, Tanya; Leary, Thomas; Cloherty, Gavin; Gaggar, Anuj; Kitrinos, Kathryn; Subramanian, Mani; Wong, Darren; Locarnini, Stephen
Liver Int.
Nov 2019
Background and Aim Functional cure is the major goal of chronic hepatitis B (CHB) therapy though few biomarkers predict this outcome. HBsAg epitope occupancy can be influenced by therapeutic and immune pressure. The aim of this study was to map the HBsAg epitope profiles during long-term nucleos(t)ide analogue therapy in patients with genotype A CHB, in the context of HBsAg loss (SL)/seroconversion. Methods We evaluated 25 genotype A CHB patients in the GS-US-174-0103 trial of HBeAg-positive CHB patients treated with tenofovir or adefovir for 4 years, 14 who achieved SL whilst 11 had no change. We epitope mapped the major domains of HBsAg to identify those patients with HBsAg clearance profile (CP) (loss of binding at both loops 1 and 2 epitopes of the ‘a’ determinant) vs non-clearance profile (no change in epitope recognition, or loss of epitope binding at one loop only), correlating this to on-treatment HBsAg responses. Complexed anti-HBs was also measured. Results Analysis of the HBsAg epitope profiles of the 25 patients at baseline identified no predictive correlation with SL. In contrast, analysis at week 48 and end of study (week 192) or prior to SL identified significant predictive associations between development of HBsAg CPs and outcome of functional cure. The detection of a CP also correlated with the development of an alanine aminotransferase flare and detection of anti-HBs complexed with HBsAg. Conclusion The detection of HBsAg CPs by epitope mapping represents a novel viral biomarker, reflecting an emerging anti-HBs selection pressure prior to functional cure.

Immunization of mice with chimeric antigens displaying selected epitopes confers protection against intestinal colonization and renal damage caused by Shiga toxin-producing Escherichia coli

Montero, David A.; Del Canto, Felipe; Salazar, Juan C.; Cespedes, Sandra; Cádiz, Leandro; Arenas-Salinas, Mauricio; Reyes, José; Oñate, Ángel; Vidal, Roberto M.
Sep 2019
Abstract Shiga toxin-producing Escherichia coli (STEC) cause diarrhea and dysentery, which may progress to hemolytic uremic syndrome (HUS). Vaccination has been proposed as a preventive approach against STEC infection; however, there is no vaccine for humans and those used in animals reduce but do not eliminate the intestinal colonization of STEC. The OmpT, Cah and Hes proteins are widely distributed among clinical STEC strains and are recognized by serum IgG and IgA in patients with HUS. Here, we develop a vaccine formulation based on two chimeric antigens containing epitopes of OmpT, Cah and Hes proteins against STEC strains. Intramuscular and intranasal immunization of mice with these chimeric antigens elicited systemic and local long-lasting humoral responses. However, the class of antibodies generated was dependent on the adjuvant and the route of administration. Moreover, while intramuscular immunization with the combination of the chimeric antigens conferred protection against colonization by STEC O157:H7 and the intranasal conferred protection against renal damage caused by STEC O91:H21. This pre-clinical study supports the potential use of this formulation based on recombinant chimeric proteins as a preventive strategy against STEC infections.

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