Synthetic virions reveal fatty acid-coupled adaptive immunogenicity of SARS-CoV-2 spike glycoprotein.

SARS-CoV-2 infection is a major global public health concern with incompletely understood pathogenesis. The SARS-CoV-2 spike (S) glycoprotein comprises a highly conserved free fatty acid binding pocket (FABP) with unknown function and evolutionary selection advantage1,2. Deciphering FABP impact on COVID-19 progression is challenged by the heterogenous nature and large molecular variability of live virus. Here we create synthetic minimal virions (MiniVs) of wild-type and mutant SARS-CoV-2 with precise molecular composition and programmable complexity by bottom-up assembly. MiniV-based systematic assessment of S free fatty acid (FFA) binding reveals that FABP functions as an allosteric regulatory site enabling adaptation of SARS-CoV-2 immunogenicity to inflammation states via binding of pro-inflammatory FFAs. This is achieved by regulation of the S open-to-close equilibrium and the exposure of both, the receptor binding domain (RBD) and the SARS-CoV-2 RGD motif that is responsible for integrin co-receptor engagement. We find that the FDA-approved drugs vitamin K and dexamethasone modulate S-based cell binding in an FABP-like manner. In inflammatory FFA environments, neutralizing immunoglobulins from human convalescent COVID-19 donors lose neutralization activity. Empowered by our MiniV technology, we suggest a conserved mechanism by which SARS-CoV-2 dynamically couples its immunogenicity to the host immune response.

Design of a Novel Multi-Epitope Vaccine Against Echinococcus granulosus in Immunoinformatics.

All the time, echinococcosis is a global zoonotic disease which seriously endangers public health all over the world. In order to speed up the development process of anti-Echinococcus granulosus vaccine, at the same time, it can also save economic cost. In this study, immunoinformatics tools and molecular docking methods were used to predict and screen the antigen epitopes of Echinococcus granulosus, to design a multi-epitope vaccine containing B- and T-cell epitopes. The multi-epitope vaccine could activate B lymphocytes to produce specific antibodies theoretically, which could protect the human body against Echinococcus granulosus infection. It also could activate T lymphocytes and clear the infected parasites in the body. In this study, four CD8+ T-cell epitopes, three CD4+ T-cell epitopes and four B-cell epitopes of Protein EgTeg were identified by immunoinformatics methods. Meanwhile, three CD8+ T-cell epitopes, two CD4+ T-cell epitopes and four B-cell epitopes of Protein EgFABP1 were identified. We constructed the multi-epitope vaccine using linker proteins. The study based on the traditional methods of antigen epitope prediction, further optimized the prediction results combined with molecular docking technology and improved the precision and accuracy of the results. Finally, in vivo and in vitro experiments had verified that the vaccine designed in this study had good antigenicity and immunogenicity.

GENE EXPRESSION LEVEL, IMMUNOLOCALIZATION, AND FUNCTION OF FATTY ACID-BINDING PROTEIN FROM SCHISTOSOMA JAPONICUM.

The Schistosoma japonicum fatty acid-binding protein (FABP) is used in the cell membrane to absorb and transport fatty acids, which cannot be resynthesized by the organism and combined with hydrophobic ligands. Among the 5 stages of the worm life cycle examined, FABP messenger ribonucleic acid (mRNA) expression was highest in male adult worms, followed by the liver-stage schistosome, and was the lowest in the lung-stage schistosome. The fabp gene-coding region was cloned and expressed to obtain recombinant S. japonicum FABP (rSjFABP) with a molecular weight of approximately 18 kDa. Mice were then immunized against rSjFABP to prepare anti-FABP serum. Using immunohistochemical techniques, FABP protein was found to localize to the eggshell, parenchyma, and digestive tract. Double-stranded RNA-mediated knockdown of FABP mRNA by RNA interference decreased the number of transcripts by >70%. Moreover, the egg production rate decreased, whereas the abnormal egg ratio was significantly increased in the FABP-silenced group compared with the negative control group (P < 0.05). These results demonstrate that FABP localizes in adults and in various stages. FABP contributes to the egg-laying capacity of adults, which may be related to the reproductive function of S. japonicum.

COVID-19 and RA share an SPP1 myeloid pathway that drives PD-L1+ neutrophils and CD14+ monocytes.

We explored the potential link between chronic inflammatory arthritis and COVID-19 pathogenic and resolving macrophage pathways and their role in COVID-19 pathogenesis. We found that bronchoalveolar lavage fluid (BALF) macrophage clusters FCN1+ and FCN1+SPP1+ predominant in severe COVID-19 were transcriptionally related to synovial tissue macrophage (STM) clusters CD48hiS100A12+ and CD48+SPP1+ that drive rheumatoid arthritis (RA) synovitis. BALF macrophage cluster FABP4+ predominant in healthy lung was transcriptionally related to STM cluster TREM2+ that governs resolution of synovitis in RA remission. Plasma concentrations of SPP1 and S100A12 (key products of macrophage clusters shared with active RA) were high in severe COVID-19 and predicted the need for Intensive Care Unit transfer, and they remained high in the post-COVID-19 stage. High plasma levels of SPP1 were unique to severe COVID-19 when compared with other causes of severe pneumonia, and IHC localized SPP1+ macrophages in the alveoli of COVID-19 lung. Investigation into SPP1 mechanisms of action revealed that it drives proinflammatory activation of CD14+ monocytes and development of PD-L1+ neutrophils, both hallmarks of severe COVID-19. In summary, COVID-19 pneumonitis appears driven by similar pathogenic myeloid cell pathways as those in RA, and their mediators such as SPP1 might be an upstream activator of the aberrant innate response in severe COVID-19 and predictive of disease trajectory including post-COVID-19 pathology.

Intestinal permeability correlates with behavioural severity in very young children with ASD: A preliminary study.

Systemic inflammation is known to alter behaviour, and since it has been reported that individuals with autism spectrum disorder (ASD) have higher levels of circulating cytokines, it has been hypothesized that systemic inflammation may exacerbate behaviours characteristic of ASD. The acute phase proteins α-2-macroglobulin, C-reactive protein, haptoglobin, serum amyloid P, serum amyloid A, ferritin and tissue plasminogen activator, as well as markers of intestinal permeability (intestinal fatty acid binding protein and lipopolysaccharide) were quantitated in the plasma of very young children with ASD. Behaviour severity was measured using the Autism Diagnostic Interview-Revised (ADI-R), the Autism Diagnostic Observation Schedule (ADOS) and the Vineland Adaptive Behaviour Scale (VABS). An increase in circulating I-FABP correlated with more severe deficits in communication, communication + social interaction as well as maladaptive behaviour. The acute phase protein haptoglobin was associated with more severe social interaction and communication + social interaction. In summary, I-FABP, a marker of intestinal epithelial damage, was associated with more severe behavioural phenotypes in very young children with ASD. In addition, the acute phase protein, haptoglobin, was associated with behaviour.

The fatty acid-binding protein (FABP) decreases the clinical signs and modulates immune responses in a mouse model of experimental autoimmune encephalomyelitis (EAE).

BACKGROUND: An increasing body of studies has shown that Fasciola hepatica can affect immune responses. This study explored whether the fatty acid-binding protein (FABP) of F. hepatica can modulate the immune system in a mouse model of experimental autoimmune encephalomyelitis (EAE). METHODS: EAE-induced C57BL/6 mice were treated with vehicle, F. hepatica total extract (TE) or FABP. The clinical signs, body weights, and the expression of IFN-γ, T-bet, IL-4, GATA3, IL-17, RORγ, TGF-ß, FOXP3, IL-10, TNF-α genes and proteins were determined in the isolated CD4+ splenocytes. Besides, the percentage of Treg cells and degree of demyelination were evaluated. RESULTS: We found that TE and FABP treatments decreased the clinical scores, lymphocyte infiltration rate, and demyelinated plaques in EAE mice. The expressions of IL-4 and GATA3 were increased, whereas IL-17 and TNF-α were down-regulated. FABP did not affect the expression of IFN-γ, RORγ, IL-10, and TGF-ß genes or proteins but reduced the expression of T-bet. TE administration did not affect the expression of IL-10 and the Tbet genes, and increased the expression levels of IFN-γ and FOXP3 in CD4+ lymphocytes. Both FABP and TE treatment did not affect the Treg cell percentage. CONCLUSION: This study indicates that F. hepatica FABP and TE can suppress the inflammatory responses in EAE-induced mice and shift the immune system toward Th2 responses. However, FABP exerts stronger anti-inflammatory effects and seems to be more effective than TE for EAE treatment.

Fatty acid binding protein 4 promotes autoimmune diabetes by recruitment and activation of pancreatic islet macrophages.

Both innate and adaptive immune cells are critical players in autoimmune destruction of insulin-producing ß cells in type 1 diabetes. However, the early pathogenic events triggering the recruitment and activation of innate immune cells in islets remain obscure. Here we show that circulating fatty acid binding protein 4 (FABP4) level was significantly elevated in patients with type 1 diabetes and their first-degree relatives and positively correlated with the titers of several islet autoantibodies. In nonobese diabetic (NOD) mice, increased FABP4 expression in islet macrophages started from the neonatal period, well before the occurrence of overt diabetes. Furthermore, the spontaneous development of autoimmune diabetes in NOD mice was markedly reduced by pharmacological inhibition or genetic ablation of FABP4 or adoptive transfer of FABP4-deficient bone marrow cells. Mechanistically, FABP4 activated innate immune responses in islets by enhancing the infiltration and polarization of macrophages to proinflammatory M1 subtype, thus creating an inflammatory milieu required for activation of diabetogenic CD8+ T cells and shift of CD4+ helper T cells toward Th1 subtypes. These findings demonstrate FABP4 as a possible early mediator for ß cell autoimmunity by facilitating crosstalk between innate and adaptive immune cells, suggesting that pharmacological inhibition of FABP4 may represent a promising therapeutic strategy for autoimmune diabetes.

Fatty acid-binding protein 5 limits ILC2-mediated allergic lung inflammation in a murine asthma model.

Dietary obesity is regarded as a problem worldwide, and it has been revealed the strong linkage between obesity and allergic inflammation. Fatty acid-binding protein 5 (FABP5) is expressed in lung cells, such as alveolar epithelial cells (ECs) and alveolar macrophages, and plays an important role in infectious lung inflammation. However, we do not know precise mechanisms on how lipid metabolic change in the lung affects allergic lung inflammation. In this study, we showed that Fabp5-/- mice exhibited a severe symptom of allergic lung inflammation. We sought to examine the role of FABP5 in the allergic lung inflammation and demonstrated that the expression of FABP5 acts as a novel positive regulator of ST2 expression in alveolar ECs to generate retinoic acid (RA) and supports the synthesis of RA from type II alveolar ECs to suppress excessive activation of innate lymphoid cell (ILC) 2 during allergic lung inflammation. Furthermore, high-fat diet (HFD)-fed mice exhibit the downregulation of FABP5 and ST2 expression in the lung tissue compared with normal diet (ND)-fed mice. These phenomena might be the reason why obese people are more susceptible to allergic lung inflammation. Thus, FABP5 is potentially a therapeutic target for treating ILC2-mediated allergic lung inflammation.

Serum amyloid A is a soluble pattern recognition receptor that drives type 2 immunity.

The molecular basis for the propensity of a small number of environmental proteins to provoke allergic responses is largely unknown. Herein, we report that mite group 13 allergens of the fatty acid-binding protein (FABP) family are sensed by an evolutionarily conserved acute-phase protein, serum amyloid A1 (SAA1), that promotes pulmonary type 2 immunity. Mechanistically, SAA1 interacted directly with allergenic mite FABPs (Der p 13 and Blo t 13). The interaction between mite FABPs and SAA1 activated the SAA1-binding receptor, formyl peptide receptor 2 (FPR2), which drove the epithelial release of the type-2-promoting cytokine interleukin (IL)-33 in a SAA1-dependent manner. Importantly, the SAA1-FPR2-IL-33 axis was upregulated in nasal epithelial cells from patients with chronic rhinosinusitis. These findings identify an unrecognized role for SAA1 as a soluble pattern recognition receptor for conserved FABPs found in common mite allergens that initiate type 2 immunity at mucosal surfaces.

Identification of B Cell Epitopes of Blo t 13 Allergen and Cross-Reactivity with Human Adipocytes and Heart Fatty Acid Binding Proteins.

Cross-reactivity between allergens and human proteins could have a clinical impact in allergic diseases. Blo t 13 is an allergen from the mite Blomia tropicalis, which belongs to the fatty acid binding protein (FABP) family and has structural homology with human FABPs. This work aimed to map B cell epitopes on Blo t 13 and to identify epitopes involved in cross-reactivity with human heart FABP (FABP3) and adipocyte FABP (FABP4). Sera from 25 patients with house dust mite (HDM) allergy that were sensitized to Blo t 13 were used for testing the reactivity of immunoglobulin E (IgE) and IgG to FABP. The epitope mapping of Blo t 13 was performed using overlapping peptides, and cross-reactivity between Blo t 13 and human FABP was analyzed using human sera and anti-Blo t 13 monoclonal antibodies. IgE antibodies to all FABPs were detected in 14/25 serum samples, and IgG was detected in 25/25 serum samples. The cross-reactivity of Blo t 13 was 42% with FABP3 and 48% with FABP4. Two IgE-binding regions were identified in Blo t 13; one between residues 54 and 72 (the main cross-reacting region) and another between residues 111 to 129. Our results suggest that exposure to the Blo t 13 allergen could induce an auto-reactive response to endogenous FABP in allergic patients sensitized to Blo t 13.

Effect of Cytotoxic T-Lymphocyte Antigen-4 on the Efficacy of the Fatty Acid-Binding Protein Vaccine Against Schistosoma japonicum.

The present study evaluated the impact of blocking cytotoxic T-lymphocyte antigen-4 (CTLA-4) activity on the protective effect elicited by the fatty acid binding protein (FABP) vaccine against Schistosoma japonicum infection. Mice were randomly divided into uninfected, infected control, anti-CTLA-4 monoclonal antibody (anti-CTLA-4 mAb), FABP, and combination (anti-CTLA-4 mAb and FABP) groups. An assessment of the S. japonicum worm and egg burden in the infected mice revealed that the worm reduction-rate induced by FABP administration was increased from 26.58 to 54.61% by co-administration of the monoclonal anti-CTLA antibody (anti-CTLA-4 mAb). Furthermore, the regulatory T cell (Treg) percentage was significantly increased in mice after administration of the anti-CTLA-4 mAb, but not the FABP vaccine, and elevated levels of the cytokines interferon (IFN)-γ, interleukin (IL)-2, IL-4, and IL-5 were observed in infected mice that were administered the anti-CTLA-4 mAb. Notably, the diameter of egg granulomas in the anti-CTLA-4 mAb and combination groups was significantly increased compared to that observed in the infected control group. Together, these results suggest that co-administering the FABP vaccine and anti-CTLA-4 treatment may have synergistically increased the immunoprotective effect of the FABP vaccine by promoting T-helper 1-type immune responses, while incurring increased tissue damage.

Effects of host fatty acid-binding protein 4 on Eimeria tenella sporozoites invasion of cells.

In our previous study, proteomics analyses of host cells infected with Eimeria tenella sporozoites coupled with isobaric tags for relative and absolute quantitation, identified several host proteins related to Eimeria invasion. In this study, A 458-bp Gallus gallus fatty acid-binding protein 4 (FABP4) gene was cloned and subcloned to pET-28c(+) vector to construct the prokaryotic recombinant expression plasmid pET-28c(+)-FABP4. The 18.5 kDa recombinant FABP4 protein (rFABP4) was expressed and identified by western blotting. Expression of FABP4 in E. tenella sporozoite-infected DF-1 cells was downregulated significantly than in non-infected cells detected by western blotting and immunohistochemistry. The antibody inhibition assay showed that antibodies against FABP4 at 50, 100, 200, 300, and 400 µg/mL had no significant effect on sporozoite invasion. BMS-309403 and transforming growth factor-ß3 (TGF-ß3) was used to inhibit and improve the expression of FABP4 in DF-1 cells, respectively, and their effect on the sporozoite invasion of cells was detected by flow cytometry. Sporozoite invasion rate in the BMS-309403-treated group was not significantly affected; however, the invasion rate in the TGF-ß3-treated group declined significantly. These results show that host FABP4 plays a negative role in Eimeria invasion. However, further studies are needed to elucidate the exact mechanism of how FABP4 negatively regulates Eimeria invasion.

Effect of regulatory T cells on the efficacy of the fatty acid-binding protein vaccine against Schistosoma japonicum.

Schistosomiasis is one of the most devastating parasitic diseases, making it imperative to develop efficient vaccines to control the causative flatworms called schistosomes. Regulatory T cells (Tregs) and the Th1 immune response have been implicated in the effectiveness of vaccines to control schistosomiasis, but the mechanisms underlying their effects are unclear. In this study, we evaluated the role of Tregs on the efficacy of the 14 kDa FABP (fatty acid-binding protein) vaccine against Schistosoma japonicum. BALB/c female mice were randomly divided into five groups: an uninfected group, infected control group, anti-CD25 monoclonal antibody (anti-CD25 mAb) group, FABP group, and combined anti-CD25 mAb and FABP group. Compared with FABP alone, a combined treatment with FABP and anti-CD25 mAb increased the rate of S. japonicum inhibition in mice from 30.3 to 56.08% and decreased the number of eggs per gram of liver. Compared with that of the infected control group, the percentage of Tregs in the spleen decreased significantly after single or combined treatment with FABP and anti-CD25 mAb, while it increased gradually in the anti-CD25 mAb group. Further, the secretion of Th1 cytokines, IFN-γ, and IL-2 increased in splenocytes in the anti-CD25 mAb group. Our results indicate that anti-CD25 mAb partially blocks Tregs and concomitantly enhances the Th1 type immune response, thereby enhancing the protective effect of the FABP vaccine.

Macrophage FABP4 is required for neutrophil recruitment and bacterial clearance in Pseudomonas aeruginosa pneumonia.

Fatty acid binding protein 4 (FABP4), an intracellular lipid chaperone and adipokine, is expressed by lung macrophages, but the function of macrophage-FABP4 remains elusive. We investigated the role of FABP4 in host defense in a murine model of Pseudomonas aeruginosa pneumonia. Compared with wild-type (WT) mice, FABP4-deficient (FABP4-/-) mice exhibited decreased bacterial clearance and increased mortality when challenged intranasally with P. aeruginosa. These findings in FABP4-/- mice were associated with a delayed neutrophil recruitment into the lungs and were followed by greater acute lung injury and inflammation. Among leukocytes, only macrophages expressed FABP4 in WT mice with P. aeruginosa pneumonia. Chimeric FABP4-/- mice with WT bone marrow were protected from increased mortality seen in chimeric WT mice with FABP4-/- bone marrow during P. aeruginosa pneumonia, thus confirming the role of macrophages as the main source of protective FABP4 against that infection. There was less production of C-X-C motif chemokine ligand 1 (CXCL1) in FABP4-/- alveolar macrophages and lower airway CXCL1 levels in FABP4-/- mice. Delivering recombinant CXCL1 to the airways protected FABP4-/- mice from increased susceptibility to P. aeruginosa pneumonia. Thus, macrophage-FABP4 has a novel role in pulmonary host defense against P. aeruginosa infection by facilitating crosstalk between macrophages and neutrophils via regulation of macrophage CXCL1 production.-Liang, X., Gupta, K., Rojas Quintero, J., Cernadas, M., Kobzik, L., Christou, H., Pier, G. B., Owen, C. A., Çataltepe, S. Macrophage FABP4 is required for neutrophil recruitment and bacterial clearance in Pseudomonas aeruginosa pneumonia.

Ligand binding properties of two Brugia malayi fatty acid and retinol (FAR) binding proteins and their vaccine efficacies against challenge infection in gerbils.

Parasitic nematodes produce an unusual class of fatty acid and retinol (FAR)-binding proteins that may scavenge host fatty acids and retinoids. Two FARs from Brugia malayi (Bm-FAR-1 and Bm-FAR-2) were expressed as recombinant proteins, and their ligand binding, structural characteristics, and immunogenicities examined. Circular dichroism showed that rBm-FAR-1 and rBm-FAR-2 are similarly rich in α-helix structure. Unexpectedly, however, their lipid binding activities were found to be readily differentiated. Both FARs bound retinol and cis-parinaric acid similarly, but, while rBm-FAR-1 induced a dramatic increase in fluorescence emission and blue shift in peak emission by the fluorophore-tagged fatty acid (dansyl-undecanoic acid), rBm-FAR-2 did not. Recombinant forms of the related proteins from Onchocerca volvulus, rOv-FAR-1 and rOv-FAR-2, were found to be similarly distinguishable. This is the first FAR-2 protein from parasitic nematodes that is being characterized. The relative protein abundance of Bm-FAR-1 was higher than Bm-FAR-2 in the lysates of different developmental stages of B. malayi. Both FAR proteins were targets of strong IgG1, IgG3 and IgE antibody in infected individuals and individuals who were classified as endemic normal or putatively immune. In a B. malayi infection model in gerbils, immunization with rBm-FAR-1 and rBm-FAR-2 formulated in a water-in-oil-emulsion (®Montanide-720) or alum elicited high titers of antigen-specific IgG, but only gerbils immunized with rBm-FAR-1 formulated with the former produced a statistically significant reduction in adult worms (68%) following challenge with B. malayi infective larvae. These results suggest that FAR proteins may play important roles in the survival of filarial nematodes in the host, and represent potential candidates for vaccine development against lymphatic filariasis and related filarial infections.

Non-invasive Point-of-Care Device To Diagnose Acute Mesenteric Ischemia.

Inadequate blood supply to the intestine can lead to acute mesenteric ischemia (AMI), with a mortality rate ranging from 60% to 90%. This high mortality rate is partially due to late detection and the lack of efficient early diagnostic tests. There is an urgent need for a point-of-care tool for immediate bedside diagnosis. Here we present for the first time a rapid and non-invasive electrochemical biosensor device based on non-faradic impedance spectroscopy to detect intestinal fatty-acid binding protein (I-FABP) as an indication of AMI. The electrochemical biosensors consist of gold interdigitated electrodes that were fabricated using photolithographic techniques on top of silicon dioxide substrates. The electrode surfaces were functionalized with an I-FABP capture antibody (CAnB) to entice the target protein, while gold nanoparticles (GNPs) functionalized with detection antibodies (DAnB-GNPs) were utilized as a novel mechanism to enhance the detection signal. Quantification of the I-FABP concentration in the medium depended on its attachment to CAnB and DAnB-GNPs in a sandwich manner, where the latter boosts the impedance signal through its binding to the I-FABP. This non-invasive non-faradic electric biosensor device demonstrates the potential for bench-to-bedside translation with the goal of decreasing morbidity and mortality from AMI.

DNA vaccination using recombinant Schistosoma mansoni fatty acid binding protein (smFABP) gene.

Schistosomiasis is a fatal disease that has a negative impact on health and economics. Praziquantel (PZQ) is the drug of choice for schistosomiasis treatment, but it has no prophylactic effect; therefore, vaccination is an essential requirement in schistosomiasis control. This work was carried out to investigate the possible effect of DNA vaccination against Schistosoma mansoni infection using recombinant S. mansoni fatty acid binding protein (rsmFABP). The smFABP gene was cloned into the eukaryotic expression vector pcDNAI/Amp in order to obtain an smFABP-pcDNAI recombinant plasmid (DNA vaccine) and was used for the intramuscular DNA vaccination of out-bread Swiss albino mice prior to infection with S. mansoni cercariae. Infected groups, either DNA vaccinated or unvaccinated, were treated with PZQ at week 6 post-infection. After 8 weeks post-infection, all mouse groups were sacrificed and parasitological, immunological and histopathological parameters were studied. DNA vaccinated mice showed a high titer of anti-smFABP-IgG antibodies and acquired significant protection (74.2%, p < 0.01) against S. mansoni infection, with a reduction in ova and granuloma counts. DNA vaccinated and PZQ treated animals had higher titers of anti-smFABP-IgG antibodies and decreased (87%, P < 0.001) parenchymal granulomas compared to the DNA vaccinated PZQ untreated group. Infected mice, either non DNA vaccinated or vaccinated, had very high collagen content and fibrous granulomas (74%) compared to the PZQ treated group (10.3% fibrous granuloma) and PZQ treated + DNA vaccinated group (0% fibrous granuloma). In conclusion, DNA vaccination had protective and anti-pathological effects in naive mice and greatly improved the pathological status in PZQ-treated animals, suggesting an immunological and pathological modulating effect of PZQ treatment.

Fabrication of Tris(bipyridine)ruthenium(II)-Functionalized Metal-Organic Framework Thin Films by Electrochemically Assisted Self-Assembly Technique for Electrochemiluminescent Immunoassay.

A simple strategy for one-step fabrication of tris(bipyridine)ruthenium(II) (Ru(bpy)32+)-functionalized metal-organic framework (Ru-MOF) thin films using a self-assembly approach assisted by an electrochemical way was introduced. In this protocol, the electrochemically driven cooperative reaction of Ru(bpy)32+ as an electrochemiluminescent (ECL) probe and a structure-directing agent, trimesic acid (H3btc) as a ligand, and Zn(NO3)2 as the Zn2+ source leads to an one-step and simultaneous synthesis and deposition of the MOF onto the electrode surface. Characterization of the Ru-MOF thin films was performed with scanning electron microscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. Scanning ion conductance microscopy was specially applied in situ to image the topography and thickness of the Ru-MOF thin films. The Ru-MOF thin films as a sensing platform show excellent ECL behavior because of plenty of Ru(bpy)32+ molecules encapsulated in the frameworks. On the basis of the Ru-MOF modified electrodes, an ultrasensitive label-free ECL immunosensing method for the human heart-type fatty-acid-binding protein has been developed with a wide linear response range (150 fg mL-1-150 ng mL-1) and a very low limit of detection (2.6 fg mL-1). The prepared immunosensor also displayed excellent stability and good specificity in the test of practical samples.

FABP4 inhibitors suppress inflammation and oxidative stress in murine and cell models of acute lung injury.

Acute lung injury (ALI) is a severe disease with high morbidity and mortality, and is characterized by devastating inflammation of the lung and increased production of reactive oxygen species (ROS). Recent studies have indicated that fatty acid binding protein (FABP4) is important in the regulation of inflammation. However, the role of FABP4 in sepsis-related ALI, and the specific mechanism of action have not been examined. In vitro, the exposure of human alveolar epithelial A549 cells to lipopolysaccharide (LPS) and recombinant FABP4 (hrFABP4) resulted in the production of pro-inflammatory cytokines, inflammatory cytokines, and ROS, while these changes were ameliorated by pretreatment with the FABP4 inhibitor BMS309403 and FABP4 siRNA. Sequentially, treatment of A549 cells with N-acetylcysteine (NAC) significantly attenuated LPS and hrFABP4-induced the generation of ROS and the release of inflammatory cytokines. In vivo, a cecal ligation and puncture (CLP)-induced ALI murine model was successfully established. Then, the mice were treated with FABP4 inhibitor BMS309403. The results showed treatment with BMS309403 improved the survival rate of CLP-induced ALI mice, and prevented lung inflammation, histopathological changes, and increase of FABP4 induced by CLP. These data indicate that FABP4 plays an important role in lung inflammation of sepsis-induced ALI. Blockade of FABP4 signaling exhibits a protective effect in a CLP-induced ALI mouse model, and in A549 cell LPS specifically induces enhanced expression of FABP4, which then causes inflammatory cytokine production by elevating the ROS level.

The Occurrence of Antibodies Against Gluten in Children with Autism Spectrum Disorders Does Not Correlate with Serological Markers of Impaired Intestinal Permeability.

There is evidence that children with autism spectrum disorders (ASDs) display an increased immune reactivity against gluten, which is supposed to be the effect of intestinal barrier abnormalities. The aim of study was to evaluate the relation of antibody induced by gluten to zonulin and intestinal fatty acid binding proteins (I-FABP), that is, serological markers of an impaired gut barrier. The study included 77 patients with ASDs. Zonulin, I-FABP, celiac-specific antibodies, anti-gliadin antibodies (AGA), and antibodies against neural transglutaminase 6 (TG6) of immunoglobulin (Ig) A and IgG classes were detected in sera. Celiac-specific antibodies were negative in all ASD children, four children (5.2%) had positive anti-TG6 antibodies, and increased AGA-IgG production was found in 21 patients (27.3%). Mean levels of zonulin and I-FABP in ASD patients were similar to those found in healthy controls and revealed a negative correlation with age, whereas regression analysis revealed a significant positive relationship between antibody production and the age. Serum concentrations of zonulin and I-FABP showed no statistically significant association with antibody positivity. An increased production of antibodies related to gliadin and neural TG6 in ASD children is not related to serological markers of an impaired intestinal barrier.