An ApoA-I Mimic Peptide of 4F Promotes SDF-1α Expression in Endothelial Cells Through PI3K/Akt/ERK/HIF-1α Signaling Pathway

Atherosclerosis (AS) seriously impairs the health of human beings and is manifested initially as endothelial cells (ECs) impairment and dysfunction in vascular intima, which can be alleviated through mobilization of endothelial progenitor cells (EPCs) induced by stromal-cell-derived factor-1α (SDF-1α). A strong inverse correlation between HDL and AS has been proposed. The aim of the present work is to investigate whether 4F, an apolipoprotein A-I (apoA-I, major component protein of HDL) mimic peptide, can upregulate SDF-1α in mice and human umbilical vein endothelial cells (HUVECs) and the underlying mechanism. The protein levels of SDF-1α were measured by ELISA assay. Protein levels of HIF-1α, phosphorylated Akt (p-Akt), and phosphorylated ERK (p-ERK) were evaluated by Western blotting analysis. The results show that L-4F significantly upregulates protein levels of HIF-1α, Akt, and ERK, which can be inhibited by the PI3K inhibitor, LY294002, or ERK inhibitor, PD98059, respectively. Particularly, LY294002 can downregulate the levels of p-ERK, while PD98059 cannot suppress that of p-Akt. D-4F can upregulate the levels of HIF, p-Akt, and p-ERK in the abdominal aorta and inferior vena cava from mice. These results suggest that 4F promotes SDF-1α expression in ECs through PI3K/Akt/ERK/HIF-1α signaling pathway.

Dramatically Enhancing the Sensitivity of Immunoassay for Ochratoxin A Detection by Cascade-Amplifying Enzyme Loading

Enzyme-linked immunosorbent assay (ELISA) is widely used in the routine screening of mycotoxin contamination in various agricultural and food products. Herein, a cascade-amplifying system was introduced to dramatically promote the sensitivity of an immunoassay for ochratoxin A (OTA) detection. Specifically, a biotinylated M13 bacteriophage was introduced as a biofunctional competing antigen, in which a seven-peptide OTA mimotope fused on the p3 protein of M13 was used to specifically recognize an anti-OTA monoclonal antibody, and the biotin molecules modified on capsid p8 proteins were used in loading numerous streptavidin-labeled polymeric horseradish peroxidases (HRPs). Owing to the abundance of biotinylated p8 proteins in M13 and the high molar ratio between HRP and streptavidin in streptavidin-polyHRP, the loading amount of HRP enzymes on the M13 bacteriophage were greatly boosted. Hence, the proposed method exhibited high sensitivity, with a limit of detection of 2.0 pg/mL for OTA detection, which was 250-fold lower than that of conventional ELISA. In addition, the proposed method showed a slight cross-reaction of 2.3% to OTB, a negligible cross-reaction for other common mycotoxins, and an acceptable accuracy for OTA quantitative detection in real corn samples. The practicability of the method was further confirmed with a traditional HRP-based ELISA method. In conclusion, the biotinylated bacteriophage and polyHRP structure showed potential as a cascade-amplifying enzyme loading system for ultra-trace OTA detemination, and its application can be extended to the detection of other analytes by altering specific mimic peptide sequences.

Serum apolipoprotein A-I depletion is causative to silica nanoparticles–induced cardiovascular damage

The rapid development of nanotechnology has greatly benefited modern science and engineering and also led to an increased environmental exposure to nanoparticles (NPs). While recent research has established a correlation between the exposure of NPs and cardiovascular diseases, the intrinsic mechanisms of such a connection remain unclear. Inhaled NPs can penetrate the air–blood barrier from the lung to systemic circulation, thereby intruding the cardiovascular system and generating cardiotoxic effects. In this study, on-site cardiovascular damage was observed in mice upon respiratory exposure of silica nanoparticles (SiNPs), and the corresponding mechanism was investigated by focusing on the interaction of SiNPs and their encountered biomacromolecules en route. SiNPs were found to collect a significant amount of apolipoprotein A-I (Apo A-I) from the blood, in particular when the SiNPs were preadsorbed with pulmonary surfactants. While the adsorbed Apo A-I ameliorated the cytotoxic and proinflammatory effects of SiNPs, the protein was eliminated from the blood upon clearance of the NPs. However, supplementation of Apo A-I mimic peptide mitigated the atherosclerotic lesion induced by SiNPs. In addition, we found a further declined plasma Apo A-I level in clinical silicosis patients than coronary heart disease patients, suggesting clearance of SiNPs sequestered Apo A-I to compromise the coronal protein’s regular biological functions. Together, this study has provided evidence that the protein corona of SiNPs acquired in the blood depletes Apo A-I, a biomarker for prediction of cardiovascular diseases, which gives rise to unexpected toxic effects of the nanoparticles.

Eco-Friendly Fluorescent ELISA Based on Bifunctional Phage for Ultrasensitive Detection of Ochratoxin A in Corn

Conventional enzyme-linked immunosorbent assay (ELISA) is commonly used for Ochratoxin A (OTA) screening, but it is limited by low sensitivity and harmful competing antigens of enzyme-OTA conjugates. Herein, a bifunctional M13 bacteriophage with OTA mimotopes fused on the p3 protein and biotin modified on major p8 proteins was introduced as an eco-friendly competing antigen and enzyme container for enhanced sensitivity. Mercaptopropionic acid-modified quantum dots (MPA-QDs), which are extremely sensitive to hydrogen peroxide, were chosen as fluorescent signal transducers that could manifest glucose oxidase-induced fluorescence quenching in the presence of glucose. On these bases, a highly sensitive and eco-friendly fluorescent immunoassay for OTA sensing was developed. Under optimized conditions, the proposed method demonstrates a good linear detection of OTA from 4.8 to 625 pg/mL and a limit of detection (LOD) of 5.39 pg/mL. The LOD is approximately 26-fold lower than that of a conventional horse radish peroxidase (HRP) based ELISA and six-fold lower than that of a GOx-OTA conjugate-based fluorescent ELISA. The proposed method also shows great specificity and accepted accuracy for analyzing OTA in real corn samples. The detection results are highly consistent with those obtained using the ultra-performance liquid chromatography-fluorescence detection method, indicating the high reliability of the proposed method for OTA detection. In conclusion, the proposed method is an excellent OTA screening platform over a conventional ELISA and can be easily extended for sensing other analytes by altering specific mimic peptide sequences in phages.

The mechanism of Annexin A1 to modulate TRPV1 and nociception in dorsal root ganglion neurons

Background Annexin A1 (ANXA1) exerts anti-nociceptive effect through ANXA1 receptor formyl peptide receptor 2 (FPR2/ALX (receptor for lipoxin A4), FPR2) at the dorsal root ganglia (DRG) level. However, the mechanisms remain elucidated. By using radiant heat, hot/cold plate, tail flick, von Frey, and Randall-Selitto tests to detect nociception in intact and chemical (capsaicin, menthol, mustard oil, formalin or CFA) injected AnxA1 conditional knockout (AnxA1−/−) mice, applying calcium imaging and patch clamp recordings in cultured DRG neurons to measure neuronal excitability, conducting immunofluorescence and western blotting to detect the protein levels of TRPV1, FPR2 and its downstream molecules, and performing double immunofluorescence and co-immunoprecipitation to investigate the interaction between Calmodulin (CaM) and TRPV1; we aim to uncover the molecular and cellular mechanisms of ANXA1’s role in antinociception. Results AnxA1−/− mice exhibited significant sensitivity to noxious heat (mean ± SD, 6.2 ± 1.0 s vs. 9.9 ± 1.6 s in Hargreaves test; 13.6 ± 1.5 s vs. 19.0 ± 1.9 s in hot plate test; n = 8; P < 0.001), capsaicin (101.0 ± 15.3 vs. 76.2 ± 10.9; n = 8; P < 0.01), formalin (early phase: 169.5 ± 32.8 s vs. 76.0 ± 21.9 s; n = 8; P < 0.05; late phase: 444.6 ± 40.1 s vs. 320.4 ± 33.6 s; n = 8; P < 0.01) and CFA (3.5 ± 0.8 s vs. 5.9 ± 1.4 s; n = 8; P < 0.01). In addition, we found significantly increased capsaicin induced Ca2+ response, TRPV1 currents and neuronal firing in AnxA1 deficient DRG neurons. Furthermore, ANXA1 mimic peptide Ac2-26 robustly increased intracellular Ca2+, inhibited TRPV1 current, activated PLCβ and promoted CaM-TRPV1 interaction. And these effects of Ac2-26 could be attenuated by FPR2 antagonist Boc2. Conclusions Selective deletion of AnxA1 in DRG neurons enhances TRPV1 sensitivity and deteriorates noxious heat or capsaicin induced nociception, while ANXA1 mimic peptide Ac2-26 desensitizes TRPV1 via FPR2 and the downstream PLCβ-Ca2+-CaM signal. This study may provide possible target for developing new analgesic drugs in inflammatory pain.

SARS-CoV2- infection as a trigger of humoral response against apolipoprotein A-1

ABSTRACTAimsUnravelling autoimmune targets triggered by SARS-CoV-2 infection may provide crucial insights in the physiopathology of the disease and foster the development of potential therapeutic candidate targets and prognostic tools. We want to determine whether SARS-CoV-2 exposure could trigger a humoral response against apolipoprotein A-1 (anti-apoA-1 IgG) through molecular mimicry and assess its relationship to patient prognosis.Methods and ResultsAnti-Spike domain 1 (SD1) IgGs, anti-apoA-1 IgGs and against mimic peptides, as well as cytokines were assessed by immunoassays on a case-control (n=101), an intensive care unit (ICU; n=126) with a 28-days follow-up, and a general population cohort (n=663) with available samples in the pre and post-pandemic period. Linear sequence homologies and antibodies cross-reactivity between apoA-1, TLR2, and Spike epitopes were identified. Overall, anti-apoA-1 IgG levels were higher in COVID-19 patients or anti-SARS-CoV-2 seropositive individuals than in healthy donors or anti-SARS-CoV-2 seronegative individuals (p<0.0001). Significant and similar associations were noted between anti-apoA-1, anti-SARS-CoV-2 IgG, cytokines, and lipid profile. In ICU patients, anti-SARS-CoV-2 and anti-apoA-1 seroconversion rates displayed similar 7-days kinetics, reaching 82% for anti-apoA-1 seropositivity. C-statistics (CS) indicated that anti-Spike/TLR2 mimic-peptide IgGs displayed a significant prognostic accuracy for overall mortality at 28 days (CS: 0.64; p=0.02). In the general population, SARS-CoV-2 exposure increased baseline anti-apoA-1 IgG levels.ConclusionsCOVID-19 induces a marked humoral response against the major protein of high-density lipoproteins. As a correlate of poorer prognosis in other clinical settings, such autoimmunity signatures may relate to long-term COVID-19 prognosis assessment and warrant further scrutiny in the current COVID-19 pandemic.

Biological and physical approaches on the role of piplartine (piperlongumine) in cancer

Chronic inflammation provides a favorable microenvironment for tumorigenesis, which opens opportunities for targeting cancer development and progression. Piplartine (PL) is a biologically active alkaloid from long peppers that exhibits anti-inflammatory and antitumor activity. In the present study, we investigated the physical and chemical interactions of PL with anti-inflammatory compounds and their effects on cell proliferation and migration and on the gene expression of inflammatory mediators. Molecular docking data and physicochemical analysis suggested that PL shows potential interactions with a peptide of annexin A1 (ANXA1), an endogenous anti-inflammatory mediator with therapeutic potential in cancer. Treatment of neoplastic cells with PL alone or with annexin A1 mimic peptide reduced cell proliferation and viability and modulated the expression of MCP-1 chemokine, IL-8 cytokine and genes involved in inflammatory processes. The results also suggested an inhibitory effect of PL on tubulin expression. In addition, PL apparently had no influence on cell migration and invasion at the concentration tested. Considering the role of inflammation in the context of promoting tumor initiation, the present study shows the potential of piplartine as a therapeutic immunomodulator for cancer prevention and progression.

Mesangial Cells and Glomerular Endothelial Cells Crosstalk in Rat Anti-Thy-1 Nephritis through VEGFA/VEGFAR2 and Angpt2/Tie2 pathway

BACKGROUNDMesangial proliferative glomerulonephritis is characterized by the proliferation of mesangial cells (MCs). Endothelial cells (ECs) are affected by signals from MCs, resulting in capillary proliferation, but the specific signaling pathway associated with this activity remains unclear.RESULTSIn this study, the expression of PCNA, RECA-1 and CD34 in the glomeruli increased on the 7th day after anti-Thy-1 nephritis establishment, indicating the occurrence of ECs proliferation. After coculturing MCs and ECs in vitro, we observed that activated MCs could promote ECs proliferation, migration and α-SMA expression. Moreover, activated ECs had the same effects on MCs. RT-qPCR showed that activated MCs could increasingly secrete VEGFA, and Angpt2 expression in VEGFA-activated ECs was enhanced. Considering that Angpt2-mediated inhibition of ECs surface receptor Tie2 phosphorylation causes ECs proliferation, we hypothesized that VEGFA/VEGFR2 and Angpt2/Tie2 signaling is involved in the interaction between MCs and ECs. Our results showed that blocking VEGFA or adding the Angpt2 antagonist Angpt1 to the coculture system decreased the number of EdU-positive cells，Angpt2，p-VEGFR2 and p-MAPK expression, but increased p-Tie2 in ECs. To determine whether Angpt1 could effectively alleviate the pathological changes of anti-Thy-1 nephritis, we performed Vasculotide (Angpt1 mimic peptide) treatment assays in vivo. The results confirmed that the addition of Vasculotide could effectively reduce PCNA, RECA-1 and α-SMA expression and promote p-Tie2.CONCLUSIONIn summary, the study showed that the VEGFA/VEGFR2 and Angpt2/Tie2 signaling pathway mediate interactions between MCs and ECs, providing an important theoretical basis for the treatment of mesangial proliferative glomerulonephritis.