TGFβ1 mimetic peptide modulates immune response to grass pollen allergens in mice

Background

Transforming growth factor β1 (TGFβ1) is a cytokine that exerts immunosuppressive functions, as reflected by its ability to induce regulatory T (Treg) cell differentiation and inhibit Th1 and Th2 responses. Hence, peptides that mimic the active core domain of TGFβ1 may be promising candidates for modulation of the allergic response. This study aimed to investigate a synthetic TGFβ1 mimetic peptide (TGFβ1‐mim) for its ability to modulate the immune response during allergic sensitization to grass pollen allergens.

Methods

The in vitro action of TGFβ1‐mim was evaluated in human lung epithelial cells, Jurkat cells, and rat basophilic leukemia cells. The in vivo action was evaluated in a murine model of Phl p 5 allergic sensitization. Additionally, the Th2 modulatory response was evaluated in IL‐4 reporter mice.

Results

In vitro, TGFβ1‐mim downregulated TNF‐α production, IL‐8 gene expression, and cytokine secretion, upregulated IL‐10 secretion, and inhibited Phl p 5‐induced basophil degranulation. During Phl p 5 sensitization in mice, TGFβ1‐mim downregulated IL‐2, IL‐4, IL‐5, IL‐13, and IFN‐γ, upregulated IL‐10, and induced Treg cell production. Furthermore, mice treated with TGFβ1‐mim had lower levels of IgE, IgG1, IgG2a and higher levels of IgA antibodies than control mice. In a reporter mouse, the mimetic inhibited Th2 polarization.

Conclusion

The TGFβ1‐mim efficiently modulated various important events that exacerbate the allergic microenvironment, including the production of main cytokines that promote Th1 and Th2 differentiation, and the induction of allergen‐specific regulatory T cells, highlighting its potential use in therapeutic approaches to modulate the immune response toward environmental allergens.

Peptide-based electrochemical biosensor for juvenile idiopathic arthritis detection

Juvenile idiopathic arthritis (JIA) is a wide group of diseases, characterized by synovial inflammation and joint tissue damage. Due to the delay in the implementation of biomarkers into clinical practice and the association with severe sequels, there is an imperative need for new JIA diagnosis strategies. Electrochemical biosensors based on screen-printed electrodes and peptides are promising alternatives for molecular diagnosis. In this work, a novel biosensor for detecting juvenile idiopathic arthritis (JIA) was developed based on the immobilization of the PRF+1 mimetic peptide, as recognition biological element, on the surface of screen-printed carbon electrode. This biosensor was able to discriminate the JIA positive and negative serum samples from different individuals using differential pulse voltammetry, presenting limits of detection and quantification in diluted samples of 1:784 (v/v) and 1:235 (v/v), respectively. Evaluation by electrochemical impedance spectroscopy showed R_CT 3 times higher for JIA positive sample than for a pool of human serum samples from healthy individuals. Surface analysis of the biosensor by atomic force microscopy, after contact with JIA positive serum, presented great globular clusters irregularly distributed. The long-term stability of the biosensor was evaluated, remaining functional for over 40 days of storage (after storage at 8°C). Therefore, a simple, miniaturized and selective biosensor was developed, being the first one based on mimetic peptide and screen-printed carbon electrode, aiming at the diagnosis of the juvenile idiopathic arthritis in real serum samples.

Leishmania infantum mimotopes and a phage-ELISA assay as tools for a sensitive and specific serodiagnosis of human visceral leishmaniasis

Serological methods used to diagnose visceral leishmaniasis (VL) are considered minimally invasive, but they present problems related with their sensitivity and/or specificity. In this study, a subtractive selection using the phage display technology against antibodies from healthy subjects living in endemic and non-endemic areas of disease, as well as from Chagas disease patients and those developing active VL, was developed. The aim of this study was to select bacteriophage-fused epitopes to be used in the serodiagnosis of human VL. Eight phage clones were selected after the bio-panning rounds, and their reactivity was evaluated in a phage-ELISA assay against a human serological panel. A wild-type clone and the recombinant K39-based immunochromatographic test were used as controls. In the results, it was shown that all clones showed an excellent performance to serologically identify VL patients, demonstrating the feasibility of the isolated phages for developing a specific and sensitive serodiagnosis of human VL.

New serological tools for improved diagnosis of human tegumentary leishmaniasis

Human tegumentary leishmaniasis (HTL), characterized by skin ulcers that may spread and cause dreadful and massive tissue destruction of the nose and mouth, is considered a neglected tropical disease, and it is a serious threat to global health due to its continuous expansion, favored by the lifecycle of its causative organism that is maintained in domestic animal reservoirs and anthropophilic sand fly species. Serodiagnosis of HTL is a great challenge due to many biological factors, including hampered specificity and/or sensitivity. This investigation addresses the unmet need for new diagnostic markers of HTL, and describes a simple platform to improve the serodiagnosis. A constrained conformational phage display random peptide library combined with a magnetic microsphere-based subtraction strategy was used to identify ligands with potential diagnostic applications. Six clones were selected against IgG antibodies from HTL patients, characterized by sequencing and confirmed by a phage-ELISA using sera from patients developing visceral leishmaniasis (n=20), Chagas disease (n=10), mucosal (n=30) and cutaneous (n=20) leishmaniasis; as well as from healthy subjects living in endemic (n=20) and non-endemic (n=30) areas of leishmaniasis. A wild-type M13-phage clone and a soluble Leishmania antigenic extract were used as negative and positive controls, respectively. Three clones reached 100% sensitivity and specificity, without any cross-reactivity with sera from patients with leishmaniasis-related diseases. Briefly, we describe for the first time a set of serological markers based on three immunodominant mimotopes that showed 100% accuracy, and that could be used in a phage-ELISA assay for the HTL serodiagnosis.

A novel reactive epitope-based antigen targeted by serum autoantibodies in oligoarticular and polyarticular juvenile idiopathic arthritis and development of an electrochemical biosensor

Currently, there are no specific markers for juvenile idiopathic arthritis (JIA) diagnosis, which is based on clinical symptoms and some blood tests for diseases' exclusion. Aiming to select new epitope-based antigens (mimotopes) that could recognize circulating autoantibodies in most JIA forms, we screened a phage displayed random peptide library against IgG antibodies purified from serum of JIA patients. ELISA assay was carried out to confirm immunoreactivity of selected peptides against sera IgG antibodies from JIA patients, healthy children and patients with other autoimmune diseases. The mimotope PRF+1 fused to phage particles was able to efficiently discriminate JIA patients from controls, and for this reason was chosen to be chemically synthesized for validation in a larger sample size. The synthetic peptide was immobilized onto bioelectrodes' surface for antibody detection by electrochemical analyses through differential pulse voltammetry. The PRF+1 synthetic peptide has efficiently discriminated JIA patients from control groups (p<0.0001) with a very good accuracy (AUC>0.84; sensitivity=61%; specificity=91%). The electrochemical platform proved to be fast, low cost and effective in detecting anti-PRF+1 antibodies from JIA patients compared to healthy controls (p=0.0049). Our study describes a novel and promising epitope-based biomarker for JIA diagnosis that can become a useful tool for screening tests, which was successfully incorporated onto an electrochemical biosensor and could be promptly used in field diagnostics.

A Short Peptide That Mimics the Binding Domain of TGF-β1 Presents Potent Anti-Inflammatory Activity

The transforming growth factor beta 1 (TGF-β1) is a pleiotropic cytokine with multiple roles in development, wound healing, and immune regulation. TGF-β1-mediated immune dysfunction may lead to pathological conditions, such as inflammation. Chronic inflammatory process is characterized by a continuous release of pro-inflammatory cytokines, and the inhibition or the blockage of these cytokines signaling pathways are considered a target treatment. In this context, despite the high numbers of TGF-β-targeted pathways, the inducible regulatory T cells (iTreg) to control inflammation seems to be a promising approach. Our aim was to develop novel peptides through phage display (PhD) technology that could mimic TGF-β1 function with higher potency. Specific mimetic peptides were obtained through a PhD subtraction strategy from whole cell binding using TGF-β1 recombinant as a competitor during elution step. We have selected a peptide that seems to play an important role on cellular differentiation and modulation of TNF-α and IL-10 cytokines. The synthetic pm26TGF-β1 peptide tested in PBMC significantly down-modulated TNF-α and up-regulated IL-10 responses, leading to regulatory T cells (Treg) phenotype differentiation. Furthermore, the synthetic peptide was able to decrease leukocytes rolling in BALB/C mice and neutrophils migration during inflammatory process in C57BL/6 mice. These data suggest that this peptide may be useful for the treatment of inflammatory diseases, especially because it displays potent anti-inflammatory properties and do not exhibit neutrophils’ chemoattraction.