Defensins In Ocular Immunity

Corneal infection with P. aeruginosa results in corneal perforation in susceptible B6, but not resistant BALB/c mice. This study explored their role mBD 1-4 in corneal infection, and their potential synergy. Immunostaining and real-time RT-PCR data demonstrated that their expression was either constitutive (mBD1 and mBD2) or inducible (mBD3 and mBD4) in normal BALB/c and B6 corneas, and disparately regulated in BALB/c vs B6 corneas after infection. Knock down studies using siRNA treatment indicated that mBD2 and mBD3, but neither mBD1 nor mBD4, is required in ocular defense. Moreover, in vivo studies demonstrated individual and combined effects of mBD2 and mBD3 that modulate bacterial load, PMN infiltration, and production of pro-inflammatory molecules (e.g., IFN-gamma, MIP-2, IL-1beta, TNF-alpha), iNOS, as well as TLR signaling molecules (e.g., TLR2, TLR4, MyD88) and transcription factor NF-kappaB. Most notably, bacterial load was increased at 5 days p.i. by silencing either mBD2 or mBD3, but was elevated at both 1 and 5 days p.i. when silencing both defensins. PMN infiltration was increased at 1 day p.i. by silencing both defensins or mBD3, but not mBD2 alone. iNOS expression was elevated by silencing mBD2, but reduced after silencing mBD3 or both defensins. Additionally, cell sources of mBD2 and mBD3 in corneal stroma were identified by dual label immunostaining after infection: PMN produce both defensins, whereas macrophages and fibroblasts produce mBD2 but not mBD3. Collectively, the data provide evidence that mBD2 and mBD3 together promote resistance against corneal infection. The conclusions may be relevant to potential treatment of other ocular diseases, in addition to P. aeruginosa keratitis

Reactive Oxygen Species and p38 Mitogen-activated Protein Kinase Mediate Exercise-induced Skeletal Muscle-derived Interleukin-6 Expression

Interleukin-6 (IL-6) is a pleiotropic cytokine secreted by many different cell types, and skeletal muscle is an important source of IL-6 during exercise. Here, we studied the effects of glucose deprivation in vitro on skeletal muscle-derived IL-6 expression and release in C2C12 myocytes, as well as its regulation by p38 mitogen-activated protein kinase (p38MAPK) and reactive oxygen species (ROS). C2C12 myotubes were cultured in DMEM medium containing 4.5 g · L−1 glucose (glucose control, GC) or DMEM medium containing no glucose (glucose deprivation, GD) for 0, 6, 12, 18 and 24 hours, and then incubated with 10mM NAC (a ROS scavenger) or 10 μM SB203580 (a p38MAPK inhibitor) under either GC or GD conditions for 24 hours. IL-6 expression levels were subsequently analyzed using RT–PCR, and IL-6 protein levels in the medium were measured using ELISA. Glucose deprivation significantly enhanced IL-6 expression at 18 and 24 hours compared to the glucose control, and caused IL-6 protein levels to increase significantly over the entire 24-hour measurement period. The ROS scavenger NAC inhibited the glucose deprivation-induced release of IL-6 protein almost completely, while the p38MAPK inhibitor SB203580 inhibited glucose deprivation-induced IL-6 protein release to a lesser extent. Our study suggests that glucose deprivation in C2C12 myocytes induces IL-6 expression and release, and that this IL-6 release is mainly mediated via ROS signaling. Skeletal muscle-derived IL-6 may thus play an important role in energy metabolism during exercise

Antibody Responses and the Effects of Clinical Drugs in COVID-19 Patients

The coronavirus disease 2019 (COVID-19) emerged around December 2019 and have become a global epidemic disease currently. Specific antibodies against SAS-COV-2 could be detected in COVID-19 patients’ serum or plasma, but the clinical values of these antibodies as well as the effects of clinical drugs on humoral responses have not been fully demonstrated. In this study, 112 plasma samples were collected from 36 patients diagnosed with laboratory-confirmed COVID-19 in the Fifth Affiliated Hospital of Sun Yat-sen University. The IgG and IgM antibodies against receptor binding domain (RBD) and spike protein subunit 1 (S1) of SAS-COV-2 were detected by ELISA. We found that COVID-19 patients generated specific antibodies against SARS-CoV-2 after infection, and the levels of anti-RBD IgG within 2 to 3 weeks from onset were negatively associated with the time of positive-to-negative conversion of SARS-CoV-2 nucleic acid. Patients with severe symptoms had higher levels of anti-RBD IgG in 2 to 3 weeks from onset. The use of chloroquine did not significantly influence the patients’ antibody titer but reduced C-reaction protein (CRP) level. Using anti-viral drugs (lopinavir/ritonavir or arbidol) reduced antibody titer and peripheral lymphocyte count. While glucocorticoid therapy developed lower levels of peripheral lymphocyte count and higher levels of CRP, lactate dehydrogenase (LDH), α-Hydroxybutyrate dehydrogenase(α-HBDH), total bilirubin (TBIL), direct bilirubin (DBIL). From these results, we suggested that the anti-RBD IgG may provide an early protection of host humoral responses against SAS-COV-2 infection within 2 to 3 weeks from onset, and clinical treatment with different drugs displayed distinct roles in humoral and inflammatory responses

Fake Node Attacks on Graph Convolutional Networks

In this paper, we study the robustness of graph convolutional networks (GCNs). Previous works have shown that GCNs are vulnerable to adversarial perturbation on adjacency or feature matrices of existing nodes; however, such attacks are usually unrealistic in real applications. For instance, in social network applications, the attacker will need to hack into either the client or server to change existing links or features. In this paper, we propose a new type of “fake node attacks” to attack GCNs by adding malicious fake nodes. This is much more realistic than previous attacks; in social network applications, the attacker only needs to register a set of fake accounts and link to existing ones. To conduct fake node attacks, a greedy algorithm is proposed to generate edges of malicious nodes and their corresponding features aiming to minimize the classification accuracy on the target nodes. In addition, we introduce a discriminator to classify malicious nodes from real nodes and propose a Greedy-generative adversarial network attack to simultaneously update the discriminator and the attacker, to make malicious nodes indistinguishable from the real ones. Our non-targeted attack decreases the accuracy of GCN down to 0.03, and our targeted attack reaches a success rate of 78% on a group of 100 nodes and 90% on average for attacking a single target node

Auto-degradable and biocompatible superparamagnetic iron oxide nanoparticles/polypeptides colloidal polyion complexes with high density of magnetic material

International audienceHypothesis: superparamagnetic iron oxide nanoparticles (SPIONs) are extensively used as building block of colloidal nanocomposites for biomedical applications. Strategies employed to embed them in a biodegradable and biocompatible polymer matrix often fail to achieve a high density of loading which would greatly benefit to applications such as imaging and hyperthermia. In this study, poly(acrylic acid) coated SPION (γ-Fe2O3-PAA) are self-assembled with hydrolysable poly(serine ester) by electrostatic complexation, leading to perfectly defined spherical particles with ultra-high density of magnetic material and an ability to auto-degrade into individual SPION and biocompatible byproducts.Experiments: self-assembly and auto-degradation of γ-Fe2O3-PAA/poly(serine ester) and γ-Fe2O3-PAA/poly(serine ester)-b-PEG colloidal particles are studied by light scattering and microscopy. Colloidal stability in bio-fluids, hyperthermia under alternating magnetic field, cellular uptake, cytotoxicity and degradation of γ-Fe2O3-PAA/poly(serine ester)-b-PEG in living cells are investigated.Findings: a remarkably slow electrostatic complexation leads to dense superparamagnetic γ-Fe2O3-PAA/poly(serine ester)-b-PEG polyion complexes (PICs) with controlled sizes (150 – 500 nm) and times of degradation in aqueous solvents (700 – 5000 h). The material shows good sustainability during hyperthermia, is well taken up by MC3T3 cells and non-cytotoxic. TEM images reveal a mechanism of degradation by “peeling” and fragmentation. In cells, PICs are reduced into individual SPIONs within 72 h