Molecular mechanism underlying the TLR4 antagonistic and antiseptic activities of papiliocin, an insect innate immune response molecule.

SignificanceSimilar to mammalian TLR4/MD-2, the Toll9/MD-2-like protein complex in the silkworm, Bombyx mori, acts as an innate pattern-recognition receptor that recognizes lipopolysaccharide (LPS) and induces LPS-stimulated expression of antimicrobial peptides such as cecropins. Here, we report that papiliocin, a cecropin-like insect antimicrobial peptide from the swallowtail butterfly, competitively inhibits the LPS-TLR4/MD-2 interaction by directly binding to human TLR4/MD-2. Structural elements in papiliocin, which are important in inhibiting TLR4 signaling via direct binding, are highly conserved among insect cecropins, indicating that its TLR4-antagonistic activity may be related to insect Toll9-mediated immune response against microbial infection. This study highlights the potential of papiliocin as a potent TLR4 antagonist and safe peptide antibiotic for treating gram-negative sepsis.

Structural basis of the complementary activity of two ketosynthases in aryl polyene biosynthesis.

Aryl polyenes (APE) are one of the most widespread secondary metabolites among gram-negative bacteria. In Acinetobacter baumannii, strains belonging to the virulent global clone 2 (GC2) mostly contain APE biosynthesis genes; its relevance in elevated pathogenicity is of great interest. APE biosynthesis gene clusters harbor two ketosynthases (KSs): the heterodimeric KS-chain length factor complex, ApeO-ApeC, and the homodimeric ketoacyl-acyl carrier protein synthase I (FabB)-like KS, ApeR. The role of the two KSs in APE biosynthesis is unclear. We determined the crystal structures of the two KSs from a pathogenic A. baumannii strain. ApeO-ApeC and ApeR have similar cavity volumes; however, ApeR has a narrow cavity near the entrance. In vitro assay based on the absorption characteristics of polyene species indicated the generation of fully elongated polyene with only ApeO-ApeC, probably because of the funnel shaped active site cavity. However, adding ApeR to the reaction increases the throughput of APE biosynthesis. Mutagenesis at Tyr135 in the active site cavity of ApeR reduces the activity significantly, which suggests that the stacking of the aryl group between Tyr135 and Phe202 is important for substrate recognition. Therefore, the two KSs function complementarily in the generation of APE to enhance its production.

Movement Time of Lower Trunk Muscles during Dynamic Postural Control in Response to a Sudden Visual Stimulus during Walking: A Pilot Study.

Postural control during walking is maintained by the combination of various factors. Among these factors, adjustment of trunk movement is essential for maintaining postural control, and the response of muscles to unpredictable stimuli affects postural control. Loss of balance while walking increases the risk of accidents, the frequency of which depends on age and sex. In this study, we investigated whether there was a difference in the movement time of trunk muscles to sudden stimulation while walking according to age and sex. Fourteen healthy individuals aged 20-30 years (6 men, 8 women) and 12 individuals aged 50-70 years (4 men, 8 women) were included in the study. Movement time of bilateral erector spinae and rectus abdominis muscles in response to visual stimulation during walking was examined using surface electromyography. Movement time was calculated as the total muscle activation time excluding the reaction time. This study revealed no significant differences in movement time of the erector spinae muscles according to sex or age. The role of the rectus abdominis muscles in maintaining posture during walking was insignificant. In conclusion, the movement time of trunk muscles in response to sudden visual stimulation during walking did not differ by age or sex, and the difference in accident frequency may be associated with deterioration of other factors required to maintain posture.

Deciphering the Binding Interactions between Acinetobacter baumannii ACP and ß-ketoacyl ACP Synthase III to Improve Antibiotic Targeting Using NMR Spectroscopy.

Fatty acid synthesis is essential for bacterial viability. Thus, fatty acid synthases (FASs) represent effective targets for antibiotics. Nevertheless, multidrug-resistant bacteria, including the human opportunistic bacteria, Acinetobacter baumannii, are emerging threats. Meanwhile, the FAS pathway of A. baumannii is relatively unexplored. Considering that acyl carrier protein (ACP) has an important role in the delivery of fatty acyl intermediates to other FAS enzymes, we elucidated the solution structure of A. baumannii ACP (AbACP) and, using NMR spectroscopy, investigated its interactions with ß-ketoacyl ACP synthase III (AbKAS III), which initiates fatty acid elongation. The results show that AbACP comprises four helices, while Ca2+ reduces the electrostatic repulsion between acid residues, and the unconserved F47 plays a key role in thermal stability. Moreover, AbACP exhibits flexibility near the hydrophobic cavity entrance from D59 to T65, as well as in the α1α2 loop region. Further, F29 and A69 participate in slow exchanges, which may be related to shuttling of the growing acyl chain. Additionally, electrostatic interactions occur between the α2 and α3-helix of ACP and AbKAS III, while the hydrophobic interactions through the ACP α2-helix are seemingly important. Our study provides insights for development of potent antibiotics capable of inhibiting A. baumannii FAS protein-protein interactions.

Structural comparison of Acinetobacter baumannii ß-ketoacyl-acyl carrier protein reductases in fatty acid and aryl polyene biosynthesis.

Some Gram-negative bacteria harbor lipids with aryl polyene (APE) moieties. Biosynthesis gene clusters (BGCs) for APE biosynthesis exhibit striking similarities with fatty acid synthase (FAS) genes. Despite their broad distribution among pathogenic and symbiotic bacteria, the detailed roles of the metabolic products of APE gene clusters are unclear. Here, we determined the crystal structures of the ß-ketoacyl-acyl carrier protein (ACP) reductase ApeQ produced by an APE gene cluster from clinically isolated virulent Acinetobacter baumannii in two states (bound and unbound to NADPH). An in vitro visible absorption spectrum assay of the APE polyene moiety revealed that the ß-ketoacyl-ACP reductase FabG from the A. baumannii FAS gene cluster cannot be substituted for ApeQ in APE biosynthesis. Comparison with the FabG structure exhibited distinct surface electrostatic potential profiles for ApeQ, suggesting a positively charged arginine patch as the cognate ACP-binding site. Binding modeling for the aryl group predicted that Leu185 (Phe183 in FabG) in ApeQ is responsible for 4-benzoyl moiety recognition. Isothermal titration and arginine patch mutagenesis experiments corroborated these results. These structure-function insights of a unique reductase in the APE BGC in comparison with FAS provide new directions for elucidating host-pathogen interaction mechanisms and novel antibiotics discovery.

Anti-Endotoxin 9-Meric Peptide with Therapeutic Potential for the Treatment of Endotoxemia.

Inflammatory reactions activated by lipopolysaccharide (LPS) of gram-negative bacteria can lead to severe septic shock. With the recent emergence of multidrug-resistant gram-negative bacteria and a lack of efficient ways to treat resulting infections, there is a need to develop novel anti-endotoxin agents. Antimicrobial peptides have been noticed as potential therapeutic molecules for bacterial infection and as candidates for new antibiotic drugs. We previously designed the 9-meric antimicrobial peptide Pro9-3 and it showed high antimicrobial activity against gram-negative bacteria. Here, to further examine its potency as an anti-endotoxin agent, we examined the antiendotoxin activities of Pro9-3 and elucidated its mechanism of action. We performed a dye-leakage experiment and BODIPY-TR cadaverine and limulus amebocyte lysate assays for Pro9-3 as well as its lysine-substituted analogue and their enantiomers. The results confirmed that Pro9-3 targets the bacterial membrane and the arginine residues play key roles in its antimicrobial activity. Pro9-3 showed excellent LPS-neutralizing activity and LPS-binding properties, which were superior to those of other peptides. Saturation transfer difference-nuclear magnetic resonance experiments to explore the interaction between LPS and Pro9-3 revealed that Trp3 and Tlr7 in Pro9-3 are critical for attracting Pro9-3 to the LPS in the gram-negative bacterial membrane. Moreover, the anti-septic effect of Pro9-3 in vivo was investigated using an LPS-induced endotoxemia mouse model, demonstrating its dual activities: antibacterial activity against gram-negative bacteria and immunosuppressive effect preventing LPS-induced endotoxemia. Collectively, these results confirmed the therapeutic potential of Pro9-3 against infection of gram-negative bacteria.

Fluorogenic Probe for Detecting Active Matrix Metalloproteinase-3 (MMP-3) in Plasma and Peripheral Blood Neutrophils to Indicate the Severity of Rheumatoid Arthritis.

Diagnosis of patients with rheumatoid arthritis (RA) is essential for early and accurate drug treatment to protect the patient from joint bone erosion and relieve symptoms of the disease. In some cases, the RA patient's X-ray images and other clinical diagnostic methods are often difficult to distinguish from different diseases, such as gout, osteoarthritis, and other inflammatory conditions. Thus, methods for diagnosis of disease activity and real-time monitoring of therapeutic effect and accurate differentiation from other bone diseases are needed. In this article, we suggest a matrix metalloproteinase-3 (MMP-3)-specific protease-activated probe immobilized in vitro kit and cell staining for flow cytometry analysis as methods to support clinical diagnosis. To overcome interindividual differences, we used phorbol 12-myristate 13-acetate (PMA)-activated plasma from 269 RA patients, 49 osteoarthritis patients, and 30 healthy volunteers. The in vitro kit developed for PMA-activated plasma showed potential for identifying disease severity and distinguishing RA from other bone diseases. In particular, expression of active MMP-3 increased until the moderate disease activity and then sharply decreased at severe disease. We suggest an analysis of intracellular MMP-3-specific protease-activated probe staining by flow cytometry. Compared with anti-MMP-3 antibody staining, the results for active MMP-3 in neutrophils using the probe exactly matched the results obtained with the in vitro kit. We also confirmed that expression of active MMP-3 was mainly from neutrophils. Together, these results suggest that the MMP-3-specific protease-activated probe might be a promising noninvasive tool for accurate diagnosis of disease severity and differentiation from similar bone diseases as well as for monitoring therapeutic efficacy.

Association of depression with socioeconomic status, anticardiolipin antibodies, and organ damage in patients with systemic lupus erythematosus: results from the KORNET registry.

OBJECTIVES: Depression is more common in patients with systemic lupus erythematosus (SLE) compared to the general population. However, few studies have investigated risk factors of depression in SLE patients, and the results are inconsistent. This study evaluated the prevalence of, and risk factors for, depression in ethnically homogeneous Korean SLE patients. METHODS: In this study, 505 consecutive SLE patients were enrolled from the Korean Lupus Network registry. Demographic variables, clinical manifestations, laboratory findings, physician global assessment, and SLEDAI-2000 and SLICC damage index were recorded at enrolment. Patients were identified as having depressive symptoms using the Korean version of the Beck Depression Inventory (BDI) with a cut-off ≥16, and categorised into four groups. Multivariable logistic regression analyses were performed to identify independent risk factors for depression defined as a BDI score ≥16. RESULTS: Of the 505 patients, 97 (19.2%) were diagnosed with depression. Patients with a higher BDI score were older, more likely to be a current smoker, and had a SLICC score >1. Conversely, they had lower income and educational levels. Regarding the serologic findings, patients with a higher BDI score had lower anti-double-stranded DNA positivity and higher anticardiolipin (aCL) positivity. On multivariate analysis, the following factors were associated with depression: current smoking status (OR 2.533, p=0.049), aCL-positivity (OR 2.009, p=0.035), and a SLICC damage index score >1 (OR 2.781, p=0.039). On the other hand, high-level education (OR 0.253, p=0.024) and a high income (OR 0.228, p=0.008) were negatively associated with depression. CONCLUSIONS: Our results show that depression is prevalent in patients with SLE and multiple factors are associated with depression in SLE. These data could help guide target programmes for those at high risk of depression in SLE.

Prediction of antiarthritic drug efficacies by monitoring active matrix metalloproteinase-3 (MMP-3) levels in collagen-induced arthritic mice using the MMP-3 probe.

Active matrix metalloproteinase-3 (MMP-3) is a prognostic marker of rheumatoid arthritis (RA). We recently developed an MMP-3 probe that can specifically detect the active form of MMP-3. The aim of this study was to investigate whether detection and monitoring of active MMP-3 could be useful to predict therapeutic drug responses in a collagen-induced arthritis (CIA) model. During the period of treatment with drugs such as methotrexate (MTX) or infliximab (IFX), MMP-3 mRNA and protein levels were correlated with fluorescence signals in arthritic joint tissues and in the serum of CIA mice. Also, bone volume density and erosion in the knee joints and the paws of CIA mice were measured with microcomputed tomography (micro-CT), X-ray, and histology to confirm drug responses. In joint tissues and serum of CIA mice, strong fluorescence signals induced by the action of active MMP-3 were significantly decreased when drugs were applied. The decrease in RA scores in drug-treated CIA mice led to fluorescence reductions, mainly as a result of down-regulation of MMP-3 mRNA or protein. The micro-CT, X-ray, and histology results clearly showed marked decreases in bone and cartilage destruction, which were consistent with the reduction of fluorescence by down-regulation of active MMP-3 in drug-treated CIA mice. We suggest that the MMP-3 diagnostic kit could be used to detect and monitor the active form of MMP-3 in CIA mice serum during a treatment course and thereby used to predict the drug response or resistance to RA therapies at an earlier stage. We hope that monitoring of active MMP-3 levels in arthritis patients using the MMP-3 diagnostic kit will be a promising tool for drug discovery, drug development, and monitoring of drug responses in RA therapy.

Detection of active matrix metalloproteinase-3 in serum and fibroblast-like synoviocytes of collagen-induced arthritis mice.

The activity of rheumatoid arthritis (RA) correlates with the expression of proteases. Among several proteases, matrix metalloproteinase-3 (MMP-3) is one of the biological markers used to diagnose RA. The active form of MMP-3 is a key enzyme involved in RA-associated destruction of cartilage and bone. Thus, detection of active MMP-3 in serum or in vivo is very important for early diagnosis of RA. In this study, a soluble MMP-3 probe was prepared to monitor RA progression by detecting expression of active MMP-3 in collagen-induced arthritis (CIA) mice in vivo in both serum and fibroblast-like synoviocytes (FLSs). The MMP-3 probe exhibited strong sensitivity to MMP-3 and moderate sensitivity to MMP-7 at nanomolecular concentrations, but was not sensitive to other MMPs such as MMP-2, MMP-9, and MMP-13. In an optical imaging study, the MMP-3 probe produced early and strong NIR fluorescence signals prior to observation of erythema and swelling in CIA mice. The MMP-3 probe was able to rapidly and selectively detect and monitor active MMP-3 in diluted serum from CIA mice. Furthermore, histological data demonstrated that activated FLSs in arthritic knee joints expressed active MMP-3. Together, our results demonstrated that the MMP-3 probe may be useful for detecting active MMP-3 for diagnosis of RA. More importantly, the MMP-3 probe was able to detect active MMP-3 in diluted serum with high sensitivity. Therefore, the MMP-3 probe developed in this study may be a very promising probe, useful as a biomarker for early detection and diagnosis of RA.

Thrombosis in Behçet's disease: a Behçet's disease patient with complete thrombotic obstruction of IVC and both iliac veins and decreased protein S activity.

Behçet's disease represents a multisystemic inflammatory disease characterized by recurrent oral ulcers, genital ulcers, and uveitis. Although vascular attack and thrombosis are not major complications in Behçet's disease, they can still pose risks that must not be overlooked. In this paper, we reported that a 25-year-old female Behçet's disease patient with complete thrombotic obstruction of the inferior vena cava that was successfully treated by aspiration thrombectomy and balloon angioplasty. The procedure produced marked symptomatic improvement. Currently, data about the treatment and the prophylaxis of thrombotic events in Behçet's disease are lacking. In this case report, we hope to discuss the future direction of such studies, how we understand the mechanism of Behçet's disease hypercoagulability, and which treatments can improve thrombotic tendencies in Behçet's disease.

Rapid Atypical Progression of Neuro-Behçet's Disease Involving Whole Brainstem and Bilateral Thalami.

We present a case of Neuro-Behçet's disease with an unpredictable clinical course. A 47-year-old man was admitted to the neurosurgery department of our hospital with a mild headache. Three days after admission, his consciousness suddenly decreased and respiratory distress progressed rapidly. A brain MRI revealed that the previously observed abnormal signal had extended markedly to both the thalamic areas and the entire brain stem, and the surrounding brain parenchyma were compressed by cerebral edema. Based on the patient's symptoms of recurrent oral and genital ulcers, skin lesions, and uveitis, a rheumatologist made a diagnosis of Behçet's disease with CNS involvement. The patient was treated with high-dose methylprednisolone with respiratory assistance in the intensive care unit for 9 days and his neurologic symptoms improved remarkably. Neuro-Behçet's disease must be considered in the differential diagnosis in rapidly deteriorated young neurological patients along with a stroke, low-grade glioma, multiple sclerosis, and occlusive venous disease.