Macrophage migration inhibitory factor-mediated mast cell extracellular traps induce inflammatory responses upon Fusobacterium nucleatum infection.

Mast cell extracellular traps (MCETs) released by mast cells contribute to host defense. In this study, we investigated the effects of MCETs released from mast cells after infection with a periodontal pathogen Fusobacterium nucleatum. We found that F. nucleatum induced MCET release from mast cells, and that MCETs expressed macrophage migration inhibitory factor (MIF). Notably, MIF bound to MCETs induced proinflammatory cytokine production by monocytic cells. These findings suggest that MIF expressed on MCETs, released from mast cells upon infection with F. nucleatum, promotes inflammatory responses that may be associated with the pathogenesis of periodontal disease.

Hericium erinaceus ethanol extract and ergosterol exert anti-inflammatory activities by neutralizing lipopolysaccharide-induced pro-inflammatory cytokine production in human monocytes.

Edible mushrooms are known to exert anti-inflammatory effects. In this study, the effects of ethanol extracts from edible mushrooms, such as Hericium erinaceus, and other edible mushrooms on inflammatory responses were investigated. Experiments were conducted using the inflammatory responses of human monocytes induced by lipopolysaccharide (LPS), a bacterial component, that provokes inflammation. Notably, we demonstrated that LPS mixed with ethanol and hot water extracts derived from edible mushrooms attenuated the production of inflammatory cytokines, such as interleukin (IL)-1ß, -6, and -8, induced by LPS in human monocytic cell cultures. Moreover, we found that the ethanol extract of H. erinaceus contained ergosterol, which attenuated IL-8 production in LPS-stimulated cells. Subsequent component analysis of the ethanol extract of H. erinaceus revealed that ergosterol binds to lipid A to attenuate LPS-induced inflammation. Together, our findings suggest that ergosterol in ethanol extracts from edible mushrooms can prevent the induction of inflammation by binding to LPS.

Porphyromonas gingivalis Gingipains-Mediated Degradation of Plasminogen Activator Inhibitor-1 Leads to Delayed Wound Healing Responses in Human Endothelial Cells.

Plasminogen activator inhibitor-1 (PAI-1), a serine protease inhibitor, is constitutively produced by endothelial cells and plays a vital role in maintaining vascular homeostasis. Chronic periodontitis is an inflammatory disease characterized by bleeding of periodontal tissues that support the tooth. In this study, we aimed to determine the role of PAI-1 produced by endothelial cells in response to infections caused by the primary periodontal pathogen Porphyromonas gingivalis. We demonstrated that P. gingivalis infection resulted in significantly reduced PAI-1 levels in human endothelial cells. This reduction in PAI-1 levels could be attributed to the proteolysis of PAI-1 by P. gingivalis proteinases, especially lysine-specific gingipain-K (Kgp). We demonstrated the roles of these degradative enzymes in the endothelial cells using a Kgp-specific inhibitor and P. gingivalis gingipain-null mutants, in which the lack of the proteinases resulted in the absence of PAI-1 degradation. The degradation of PAI-1 by P. gingivalis induced a delayed wound healing response in endothelial cell layers via the low-density lipoprotein receptor-related protein. Our results collectively suggested that the proteolysis of PAI-1 in endothelial cells by gingipains of P. gingivalis might lead to the deregulation of endothelial homeostasis, thereby contributing to the permeabilization and dysfunction of the vascular endothelial barrier.

Selective inhibition mechanism of nitroxoline to the BET family: Insight from molecular simulations.

Although the proteins in bromodomain and extra-terminal domain (BET) family are promising therapy drug targets for numerous human diseases, the binding effectiveness is interfered by the competition from non-BET protein BRD9. In this study, molecular docking, molecular dynamics simulations, binding free energy calculations and per-residue energy decomposition methods were employed to clarify the selective inhibition mechanism of nitroxoline. The results showed that the different cavity volume of effective embedding inhibitor and the changes in conserved residues were associated with the significant higher selectivity of inhibitor nitroxoline for BET family than non-BET protein (BRD9). In addition, the non-polar interactions occurred in Phe83, Val87 at ZA loop, and the polar interaction appeared in Met132, Asn135 at BC loop. Therefore, when designing a new inhibitor, it could better improve the inhibitor activity by introducing the heteroatom conjugated pyridine-like moiety and the strong electron-withdrawing nitro-like moiety. Overall, this study not only clarified the molecular mechanism of the selective inhibition of nitroxoline, but also provided insight into designing more effective BET inhibitors in next step.

The interaction between serum amyloid A and Toll-like receptor 2 pathway regulates inflammatory cytokine secretion in human gingival fibroblasts.

BACKGROUND: Serum amyloid A (SAA) has been identified to trigger inflammation response, and play a crucial role in chronic inflammatory diseases. However, the regulatory mechanism of SAA still remains unclear during the development of periodontitis METHODS: SAA mRNA and protein expression were detected in healthy and inflammatory gingival tissues using real-time polymerase chain reaction (PCR) and immunohistochemistry. Human recombinant SAA (Apo-SAA), Pam3CSK4 (a Toll-like receptor (TLR) 2 ligand), siRNA-SAA, or TLR2 neutralizing antibody was applied to treat human gingival fibroblasts, respectively, or combined. SAA, TLRs, and inflammatory cytokines interleukin (IL)-6 and IL-8 were analyzed by real-time PCR, western blotting, or enzyme-linked immunosorbent assay. RESULTS: SAA expression increased in human inflammatory gingival tissues from patients with periodontitis (P <0.05). Apo-SAA could increase not only the mRNA expression of TLR2 (P <0.05), but also IL-6 and IL-8 mRNA and protein levels (P <0.05) which was suppressed by TLR2 antibody in human gingival fibroblasts. Pam3CSK4 increased SAA, IL-6, and IL-8 levels (P <0.05). However, the expression of SAA, IL-6, and IL-8 decreased after transfection of siRNA-SAA (P <0.05). CONCLUSION: SAA not only increases in inflammatory gingiva, but also triggers inflammatory cytokine secretion via interacting with TLR2 pathway in human gingival fibroblasts, which indicates that SAA is involved in periodontal inflammation.

Study on Biocompatibility of AuNPs and Theoretical Design of a Multi-CDR-Functional Nanobody.

The investigation on proteinlike specific functions of nanoparticles (NPs) has been a huge challenge. Here, the biocompatibility of Au nanoparticles (AuNPs) to antigens hen egg white lysozyme and epidermal growth factor receptor was studied first by molecular dynamics (MD) simulations and the research results revealed that antigens could form quickly a stable binding with the AuNPs and kept the structural integrity of the protein, which demonstrated better biocompatibility of AuNPs. Then, two types of complementary-determining regions (CDRs) were grafted onto the AuNPs to design a novel multi-CDR-functional nanobody. By means of MD simulations under physiological conditions, we found that the bindings of the designed nanobody and the antigens were stable and safe. Compared with the results of antigens interacting with the natural antibody, the redundant CDRs on AuNPs bound with the nonactive site in the antigens to form a stable conformation, which leaded to the powerful binding capacity of the designed nanobody than that of the natural antibody. This study provided available insights into the biocompatibility of AuNPs and important theoretical proofs to the multi-CDR-functional nanobody applied in biological systems, which were expected to help in design of novel multifunctional nanobodies.

Molecular mechanism study of several inhibitors binding to BRD9 bromodomain based on molecular simulations.

Bromodomain-containing protein 9 (BRD9) has been employed as a potential target for anticancer drugs in recent years. In this work, molecular docking, molecular dynamics (MD) simulations, binding free energy calculations, and per residue energy decomposition approaches were performed to elucidate the different binding modes between four pyridinone-like scaffold inhibitors and BRD9 bromodomain. Analysis results indicate that non-polar contribution mainly deriving from van der Waals energy is a critical impact on binding affinity of inhibitors against BRD9. Some key residues Phe44, Phe47, Val49, and Ile53 (at ZA loop) enhance the binding energy of inhibitors in BRD9 by means of providing hydrophobic interactions. Moreover, it is observed that BRD9 is anchored by the formation of a stable hydrogen bond between the carbonyl of the inhibitors and the residue Asn100 (at BC loop), and a strong π-π stacking interaction formed between the residue Tyr106 (at BC loop) and the inhibitors. The existence of dimethoxyphenyl structure and the aromatic ring merged to pyridinone scaffold are useful to enhance the BRD9 binding affinity. These findings should guide the rational design of more prospective inhibitors targeting BRD9. Communicated by Ramaswamy H. Sarma.

Molecular inhibitory mechanism study on the potent inhibitor brigatinib against four crizotinib-resistant ALK mutations.

As a potent and selective drug, brigatinib exhibits high efficacy against wild-type and mutant anaplastic lymphoma kinase (ALK) proteins to treat non-small cell lung cancer. In this work, the mechanisms of brigatinib binding to wild type and four mutant ALKs were investigated to gain insight into the dynamic energetic and structural information with respect to the design of novel inhibitors. Comparison between ALK-brigatinib and ALK-crizotinib suggests that the scaffold of brigatinib is well anchored to the residue Met1199 of hinge region by two hydrogen bonds, and the residue Lys1150 has the strong electrostatic interaction with the dimethylphosphine oxide moiety in brigatinib. These ALK mutations have significant influences on the flexibility of P-loop region and DFG sequences, but do not impair the hydrogen bonds between brigatinib and the residue Met1199 of hinge region. And mutations (L1196M, G1269A, F1174L, and R1275Q) induce diverse conformational changes of brigatinib and the obvious energy variation of residues Glu1167, Arg1209, Asp1270, and Asp1203. Together, the detailed explanation of mechanisms of those mutations with brigatinib further provide several guidelines for the development of more effective ALK inhibitors.

Molecular mechanisms of tetrahydropyrrolo[1,2-c]pyrimidines as HBV capsid assembly inhibitors.

As an attractive therapeutic strategy for chronic hepatitis B virus (HBV), HBV capsid assembly inhibitors have got increased attention, which induce aberrant capsid assembly and thereby affect viral replication. In this work, molecular docking, molecular dynamics simulations, binding free energy calculations and per-residue energy decomposition were implemented to investigate the binding mechanism between tetrahydropyrrolopyrimidines scaffold inhibitors and HBV capsid protein. The obtained results displayed that the non-polar interaction, hydrogen bond interaction, polar interaction and π-π stacking interaction together help to stabilize the conformation of inhibitors in the interface of HBV core proteins, and residues Pro25, Thr33, Trp102, Ile105, Tyr118, Ile139, Leu140 (chain B), and Val124, Trp125, Thr128, Arg133 (chain C) were important participants during binding process. The replacement of the electronegative groups F, Cl and sulphonamide in inhibitor 28a would alter the major inhibitory effects of binding and activation. The models established by three-dimensional quantitative structure-activity relationship could be used to predict the anti-HBV activities of the tetrahydropyrrolopyrimidines molecules. This study will help understanding the molecular mechanisms and novel designed small molecules could act as better inhibitors.

Selective mechanisms and molecular design of 2,4 Diarylaminopyrimidines as ALK inhibitors.

As an attractive therapeutic target for non-small-cell lung cancer (NSCLC), anaplastic lymphoma kinase (ALK) has got increased attention, and the selectivity of ALK inhibitors is an enormous challenge. Recently, 2,4-Diarylaminopyrimidines with high inhibitory activity over InsR/IGF1R were reported as ALK inhibitors, which harboring phosphine oxide moiety. In this work, it is the first time to reveal that the incorporation of dimethylphosphine oxide moiety and the smaller active pocket of ALK is key factor in the selectivity of inhibitor 11q toward ALK over IGF1R/InsR. The results of molecular simulation indicate that the subtle change in the binding pocket of ALK is mainly associated with the flexibility of P-loop and the own residues K1150 and D1270. The replacement of the dimethylphosphine oxide and methylpiperazine of inhibitor 11q would alter the major inhibitory effects of binding and activation. The results further combined 3D-QSAR can not only profile the binding mechanism between the 2,4-Diarylaminopyrimidines inhibitors and ALK, but also supply the useful information for the rational design of a more potential small molecule inhibitor bound to ALK receptor.

Molecular modeling study on resistance of WT/D473H SMO to antagonists LDE-225 and LEQ-506.

The smoothened (SMO) receptor, an essential signal transducer in the Hedgehog pathway, was targeted with antagonists to suppress the tumor. It is interesting that SMO D473H mutation confers resistance on inhibitor LDE-225 rather than LEQ-506. In this paper, the binding modes of them against the wild type and mutant SMO receptors were identified to gain insights into the resistant and non-resistant factors, based on a comprehensive protocol involving molecular docking, molecular dynamic simulations, free energy calculation and decomposition. A comparison of resistant LDE-225 and non-resistant LEQ-506 indicates that the volume of the binding cavity decreases seriously in the mutant complex with resistant LDE-225. In addition, the D473H mutation disrupts the hydrogen bond network with residues R400 and Q477, which results in the TM6 conformation inward. Owing to the absence of the hydrogen bond, residues R400 and Q477 make weak contributions to LDE-225. However, the D473H mutation along with TM6 conformational change has no effect on non-resistant LEQ-506. Finally, the resistance ascribes to adverse interaction between the greater polarity of mutant residue H473 and the nonpolar phenmethyl of LDE-225. The elaborate insights into structural and energetic mechanism of drug resistance provide an effective strategy to design rationally non-resistant antagonists.

MicroRNA-126 Regulates Inflammatory Cytokine Secretion in Human Gingival Fibroblasts Under High Glucose via Targeting Tumor Necrosis Factor Receptor Associated Factor 6.

BACKGROUND: MicroRNAs (miRs) play a crucial role in inflammatory diseases, including periodontitis. Meanwhile, miRs act as biomarkers for predicting diabetes mellitus (DM). However, the regulatory mechanism of miR-126 on development of periodontitis in patients with DM still remains unclear. METHODS: Human gingival fibroblasts were cultured with low (5.5 mmol/L), medium (15 mmol/L), and high (25 mmol/L) glucose, respectively. Expressions of miR-126, tumor necrosis factor (TNF) receptor associated factor (TRAF) 6, and related cytokines were analyzed by real-time polymerase chain reaction (PCR). After transfection with miR-126 mimic, PCR and western blot were performed to detect level of TRAF6, and luciferase reporter assay confirmed if TRAF6 is the direct target of miR-126. Production of cytokines was measured using enzyme-linked immunosorbent assay. RESULTS: Increased glucose significantly suppressed miR-126 expression in human gingival fibroblasts (P <0.05). Also, high glucose increased TRAF6, interleukin (IL)-6, TNF-α, and chemical chemokine ligand (CCL) 2 levels, whereas it decreased IL-10 level. MiR-126 mimic significantly decreased TRAF6 mRNA and protein levels under high glucose (P <0.05). Also, miR-126 directly targeted TRAF6 through binding to its 3' untranslated region in human gingival fibroblasts. Overexpression of miR-126 significantly abrogated high glucose-induced secretion of proinflammatory cytokines such as IL-6, TNF-α, and CCL2 and promoted production of IL-10. CONCLUSION: These data suggest that miR-126 inhibits inflammation of human gingival fibroblasts under high glucose through targeting TRAF6, which may be a potential therapeutic target for periodontitis concomitant with DM.

Epidemiology and risk factors for chronic kidney disease in patients with ischaemic stroke.

BACKGROUND: There is growing evidence for an association between chronic renal disease (CKD) and adverse cerebrovascular events because of the overlap of several risk factors. The purpose of this study is to examine the epidemiology of CKD and the characteristics of risk factors for CKD in the population with ischaemic stroke. METHODS: This retrospective study included 571 patients with ischaemic stroke. Estimated glomerular filtration rate (eGFR) was calculated by the Modification of Diet in Renal Disease (MDRD) study equation. Renal function was assessed according to the Kidney Disease Outcomes Quality Initiative (K/DOQI)-CKD classification. RESULTS: Study demonstrated that the major factors associated with CKD in the ischaemic stroke patients were age, diabetes mellitus, hypertension, systolic blood pressure, LDL cholesterol and serum uric acid. Diabetes mellitus (OR 4·146, 95% CI 1·047-16·418, P = 0·043), hypertension and diabetes mellitus (OR 3·574, 95% CI 1·248-10·234, P = 0·018), serum uric acid (OR 1·010, 95% CI 1·006-1·013, P < 0·001) and LDL cholesterol (OR 1·431, 95% CI 1·063-1·928, P = 0·018) were independent risk factors associated with CKD in the patients with ischaemic stroke. CONCLUSIONS: The patients with ischaemic stroke may be considered as a high-risk population for CKD and be aggressively managed for CKD prevention. The high prevalence of CKD in population with ischaemic stroke prompts the need for greater public awareness about risks of CKD.