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Diabetic kidney disease (DKD) is one of the severe complications of diabetes mellitus-related microvascular lesions, which remains the leading cause of end-stage kidney disease. The genesis and development of DKD is closely related to inflammation. Myeloid differentiation 2 (MD2) mediates hyperlyciemia-induced renal inflammation and DKD development and is considered as a potential therapeutic target of DKD. Here, we identified a new small-molecule MD2 inhibitor, JM-9. In vitro, JM-9 suppressed high glucose (HG) and palmitic acid (PA)-induced inflammation in MPMs, accompanied by inhibition of MD2 activation and the downstream TLR4/MyD88-MAPKs/NFκB pro-inflammatory signaling pathway. Macrophage-derived factors increased the fibrotic and inflammatory responses in renal tubular epithelial cells, which were inhibited by treating macrophages with JM-9. Then, we investigated the therapeutic effects against DKD in streptozotocin-induced type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) mouse models. Treatment with JM-9 prevented renal inflammation, fibrosis, and dysfunction by targeting MD2 in both T1DM and T2DM models. Our results show that JM-9, a new small-molecule MD2 inhibitor, protects against DKD by targeting MD2 and inhibiting MD2-mediated inflammation. In summary, JM-9 is a potential therapeutic agent for DKD.

Our previous study has found that aureusidin can inhibit inflammation by targeting myeloid differentiation 2 (MD2) protein. Structural optimization of aureusidin gave rise to a derivative named CNQX. LPS was used to induce inflammation in intestinal macrophages; flow cytometry, PI staining and Hoechst 33342 staining were used to detect the apoptotic level of macrophages; enzyme‐linked immunosorbent assay (ELISA) was utilized to detect the expression level of inflammatory factors (including IL‐1β, IL‐18 and TNF‐α); immunofluorescence staining was used to investigate the expression of MD2; Western blot was employed to measure the protein level of TLR4, MD2, MyD88 and p‐P65. As a result, CNQX with IC50 of 2.5 μM can significantly inhibit the inflammatory damage of macrophages, decrease apoptotic level, reduce the expression level of inflammatory factors and simultaneously decrease the expression level of TLR4, MD2, MyD88 as well as p‐P65. Caco‐2 cell line was used to simulate the intestinal mucosal barrier in vitro, LPS was employed to induce cell injury in Caco‐2 (to up‐regulate barrier permeability), and CNQX with IC50 of 2.5 μl was used for intervention. Flow cytometry was used to detect the apoptotic level of Caco‐2 cells, trans‐epithelial electric resistance (TEER) was measured, FITC‐D was used to detect the permeability of the intestinal mucosa, and Western blot was used to detect the expression levels of tight junction proteins (including occludin, claudin‐1, MyD88, TLR4 and MD2). As a result, CNQX decreased the apoptotic level of Caco‐2 cells, increased TEER value, decreased the expression levels of MyD88, TLR4 and MD2, and increased the protein levels of tight junction proteins (including occludin and claudin‐1). C57BL/6 wild‐type mice were treated with drinking water containing Dextran sulphate sodium (DSS) to establish murine chronic colitis model. After CQNX intervention, we detected the bodyweight, DAI score and H&E tissue staining to evaluate the life status and pathological changes. Immunohistochemistry (IHC) staining was used to detect the expression of MD2 protein, tight junction protein (including occludin and claudin‐1). Transmission electron microscopy and FITC‐D were used to detect intestinal mucosal permeability. Western blot was used to detect the expression levels of tight junction proteins (including occludin, claudin‐1, MyD88, TLR4 and MD2) in the intestinal mucosa tissue. Consequently, CNQX can inhibit the intestinal inflammatory response in mice with colitis, inhibit the mucosal barrier injury, increase the expression of tight junction proteins (including occludin and claudin‐1) and decrease the expression levels of MyD88, TLR4 and MD2. Mechanistically, pull‐down and immunoprecipitation assays showed that CNQX can inhibit the activation of TLR4/MD2‐NF‐κB by binding to MD2 protein. Collectively, in this study, we found that CNQX can suppress the activation of TLR4 signals by targeting MD2 protein, thereby inhibiting inflammation and mucosal barrier damage of chronic colitis. [ABSTRACT FROM AUTHOR]

Diabetic kidney disease (DKD) is one of the severe complications of diabetes mellitus-related microvascular lesions, which remains the leading cause of end-stage kidney disease. The genesis and development of DKD is closely related to inflammation. Myeloid differentiation 2 (MD2) mediates hyperlyciemia-induced renal inflammation and DKD development and is considered as a potential therapeutic target of DKD. Here, we identified a new small-molecule MD2 inhibitor, JM-9. In vitro , JM-9 suppressed high glucose (HG) and palmitic acid (PA)-induced inflammation in MPMs, accompanied by inhibition of MD2 activation and the downstream TLR4/MyD88-MAPKs/NFκB pro-inflammatory signaling pathway. Macrophage-derived factors increased the fibrotic and inflammatory responses in renal tubular epithelial cells, which were inhibited by treating macrophages with JM-9. Then, we investigated the therapeutic effects against DKD in streptozotocin-induced type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) mouse models. Treatment with JM-9 prevented renal inflammation, fibrosis, and dysfunction by targeting MD2 in both T1DM and T2DM models. Our results show that JM-9, a new small-molecule MD2 inhibitor, protects against DKD by targeting MD2 and inhibiting MD2-mediated inflammation. In summary, JM-9 is a potential therapeutic agent for DKD. [Display omitted] • We designed a new small-molecule MD2 inhibitor, JM-9, which derived from curcumin. • JM-9 attenuates renal injury, inflammation and fibrosis both in T1DM and T2DM. • JM-9 inhibites MD2 activation and downstream pathway in diabetic nephropathy. • JM-9 is expected to be a therapeutic candidate for diabetic nephropathy. [ABSTRACT FROM AUTHOR]

Abstract Inflammation plays an important role in acute lung injury (ALI). Hesperetin (HES), a natural flavanone and an aglycone of hesperidin, has established potent anti-inflammatory activity. The aim of this study was to evaluate the potential protective effect of HES on lipopolysaccharide (LPS)-induced ALI in mice and to illuminate its possible directly target. Results indicated that HES pretreatment significantly attenuated LPS-induced pulmonary pathological injury, total protein concentration, markedly decreased the number of neutrophils and the levels of inflammatory cytokines, TNF-α and IL-6, in ALI model in vivo and in vitro. Meanwhile, pretreatment with HES dramatically reduced myeloperoxidase (MPO) activity in LPS-induced ALI mice. Additionally, using molecular docking and co-immunoprecipitation assay, HES showed a directly bind with myeloid differentiation 2 (MD2), in which HES could inhibit MAPK activation, regulate IκB degradation, block the interaction MD2 and its co-receptor Toll-like receptor 4 (TLR4). Taken together, HES showed a significantly protective effect against LPS-induced ALI, which might be associated with MD2 protein. These results attested HES worthy of further progress into an adjunctive potential drug for the treatment for ALI. [ABSTRACT FROM AUTHOR]

Weitao Fu,1,* Lingfeng Chen,1,* Zhe Wang,1 Chengwei Zhao,1 Gaozhi Chen,1 Xing Liu,1 Yuanrong Dai,2 Yuepiao Cai,1 Chenglong Li,1,3 Jianmin Zhou,1 Guang Liang1 1Chemical Biology Research Center, School of Pharmaceutical Sciences, 2Department of Respiratory Medicine, the Second Affiliated Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, People’s Republic of China; 3Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, Ohio State University, Columbus, OH, USA *These authors contributed equally to this work Abstract: It is recognized that myeloid differentiation protein 2 (MD-2), a coreceptor of toll-like receptor 4 (TLR4) for innate immunity, plays an essential role in activation of the lipopolysaccharide signaling pathway. MD-2 is known as a neoteric and suitable therapeutical target. Therefore, there is great interest in the development of a potent MD-2 inhibitor for anti-inflammatory therapeutics. Several studies have reported that xanthohumol (XN), an anti-inflammatory natural product from hops and beer, can block the TLR4 signaling by binding to MD-2 directly. However, the interaction between MD-2 and XN remains unknown. Herein, our work aims at characterizing interactions between MD-2 and XN. Using a combination of experimental and theoretical modeling analysis, we found that XN can embed into the hydrophobic pocket of MD-2 and form two stable hydrogen bonds with residues ARG-90 and TYR-102 of MD-2. Moreover, we confirmed that ARG-90 and TYR-102 were two necessary residues during the recognition process of XN binding to MD-2. Results from this study identified the atomic interactions between the MD-2 and XN, which will contribute to future structural design of novel MD-2-targeting molecules for the treatment of inflammatory diseases. Keywords: myeloid differentiation 2, xanthohumol, binding mode, inflammation, molecular dynamics simulation

Obesity is a major and independent risk factor of kidney diseases. The pathogenic mechanisms of obesity-associated renal injury are recognized to at least involve a lipid-rich and pro-inflammatory state of the renal tissues, but specific mechanisms establishing causal relation remain unknown. Saturated fatty acids are elevated in obesity, and known to induce chronic inflammation in kidneys. Myeloid differentiation protein 2 ( MD2) is an important protein in lipopolysaccharide-induced innate immunity response and inflammation. We suggested that obesity-associated renal injury is regulated by MD2 thereby driving an inflammatory renal injury. The used three mouse models for in vivo study: MD2 knockout mice ( KO) maintained on high fat diet ( HFD), wild-type mice on HFD plus L6H21, a specific MD2 inhibitor and KO mice given palmitic acid ( PA) by IV injection. The in vitro studies were carried out in cultured renal tubular epithelial cells, mouse mesangial cells and primary macrophages, respectively. The HFD mice presented with increased hyperlipidemia, serum creatinine and proteinuria. Renal tissue from HFD mice had increased fibrosis, inflammatory cytokines, macrophage infiltration, and activation of NF-κB and MAPKs. This HFD-induced renal injury profile was not observed in KO mice or L6H21-treated mice. Mice given PA mimmicked the HFD-induced renal injury profiles, which were prevented by MD2 knockout. The in vitro data further confirmed MD2 mediates PA-induced inflammation. MD2 is causally related with obesity-associated renal inflammatory injury. We believe that MD2 is an attractive target for future therapeutic strategies in obesity-associated kidney diseases. [ABSTRACT FROM AUTHOR]

Acute lung injury (ALI) is an inflammation-mediated respiratory disease that is associated with a high mortality rate. In this study, a series of novel O -benzylcinnamic acid derivatives were designed and synthesized using cinnamic acid as the lead compound. We tested the preliminary anti-inflammatory activity of the compounds by evaluating their effect on inhibiting the activity of alkaline phosphatase (ALP) in Hek-Blue-TLR4 cells, in which compound L26 showed the best activity and 7-fold more active than CIN. ELISA, immunoprecipitation, and molecular docking indicated that L26 targeted MD-2 protein and competed with LPS to bind to MD-2, which resulted in the inhibition of inflammation. In the LPS-induced mouse model of ALI, L26 was found to decrease ALP activity and inflammatory cytokine TNF-α release to reduce lung injury by inhibiting the NF-κB signaling pathway. Acute toxicity experiments showed that high doses of L26 did not cause adverse reactions in mice, and it was safe in vivo. Also, the preliminary pharmacokinetic parameters of L26 were investigated in SD rats (T 1/2 = 4.246 h). In summary, L26 exhibited optimal pharmacodynamic and pharmacokinetic characteristics, which suggested that L26 could serve as a potential agent for the development of ALI treatment. [Display omitted] • A series of novel O -benzylcinnamic acid derivatives were designed and synthesized. • Anti-inflammatory effect of compounds was tested by ALP and Elisa assay in vitro. • Compound L26 targeted MD-2 protein and competed with LPS to bind to MD-2. • Compound L26 could reduce ALI by inhibiting the NF-κB signaling pathway in vivo. [ABSTRACT FROM AUTHOR]

Acute inflammatory diseases are the leading causes of mortality in intensive care units. Myeloid differentiation 2 ( MD-2) is required for recognizing lipopolysaccharide ( LPS) by toll-like receptor 4 ( TLR4), and represents an attractive therapeutic target for LPS-induced inflammatory diseases. In this study, we report a chalcone derivative, L2H21, as a new MD2 inhibitor, which could inhibit LPS-induced inflammation both in vitro and in vivo. We identify that L2H21 as a direct inhibitor of MD-2 by binding to Arg90 and Tyr102 residues in MD-2 hydrophobic pocket using a series of biochemical experiments, including surface plasmon response, molecular docking and amino acid mutation. L2H21 dose dependently inhibited LPS-induced inflammatory cytokine expression in primary macrophages. In mice with LPS intratracheal instillation, L2H21 significantly decreased LPS-induced pulmonary oedema, pathological changes in lung tissue, protein concentration increase in bronchoalveolar lavage fluid, inflammatory cells infiltration and inflammatory gene expression, accompanied with the decrease in pulmonary TLR4/ MD-2 complex. Meanwhile, administration with L2H21 protects mice from LPS-induced mortality at a degree of 100%. Taken together, this study identifies a new MD2 inhibitor L2H21 as a promising candidate for the treatment of acute lung injury ( ALI) and sepsis, and validates that inhibition of MD-2 is a potential therapeutic strategy for ALI. [ABSTRACT FROM AUTHOR]

Angiotensin II (Ang II) induces cardiac inflammation and remodeling. Emerging evidence indicates that Ang II may utilize the Toll-like receptor 4 (TLR4) signaling pathway in mediating pro-inflammatory and profibrotic activities. However, the precise mechanism is poorly understood. Myeloid differentiation 2 (MD2), a molecule that physically binds to TLR4, confers lipopolysaccharide responsiveness and may also be involved in mediating the actions of Ang II. We hypothesize that MD2 plays an essential role in cardiac inflammation and remodeling induced by local Ang II, and inhibition of MD2 can attenuate Ang II-induced cardiac dysfunction. Using a specific small molecule MD2 blocker L6H21 and the MD2 knockout mice, we show that MD2 deficiency significantly reduces cardiac inflammation and subsequent fibrosis, hypertrophy, and dysfunction in mice challenged with subc2utaneous injection of Ang II. In rat cardiomyocyte-like H9c2 cells as well as rat primary cardiomyocytes, inhibition of MD2 by L6H21 or siRNA knockdown suppressed the Ang II-induced TLR4 signaling pathway activation including MyD88 recruitment, and reduced cardiomyocyte hypertrophy and matrix protein expression. These pro-inflammatory activities of Ang II were independent of the AT1 receptor. Finally, we demonstrated the direct interaction between Ang II and MD2 protein via hydrogen bonds on Arg-90, Glu-92, and Asp-100. Ang II produces an inflammatory response and cardiac remodeling by directly binding to MD2, activating MD2/TLR4 complex, and recruiting MyD88. MD2 may be a new therapeutic target for Ang II-mediated cardiac inflammation and remodeling. [ABSTRACT FROM AUTHOR]

Abstract: Lipopolysaccharide (LPS), an endotoxin of Gram-negative bacteria, activates the innate immunity system through a receptor complex of myeloid differentiation 2 (MD-2) and toll-like receptor 4 (TLR4). MD-2 directly recognizes the lipid A domain of LPS, which triggers MD-2/TLR4-mediated cellular response aimed at eliminating the invaded pathogen. However, excess production of inflammatory mediators is harmful to host tissue and this can cause septic death in extreme cases. MD-2 represents an attractive therapeutic target of inflammatory and immune diseases in human. In particular, eritoran is a synthetic tetraacylated lipid A that binds directly to MD-2 and antagonizes LPS binding to the same site, and it ameliorates various inflammatory conditions due to infection or sterile organ injury. In this review, we outline the recent advances in the structure biology of ligand interaction with MD-2/TLR4, and highlight the MD-2-directed LPS antagonists, which are natural and synthetic chemicals, under development to treat inflammatory diseases. [Copyright &y& Elsevier]

Angiotensin II (Ang II)-induced vascular inflammation and injury entails endothelial to mesenchymal transition (EndMT). Recent studies have shown that Ang II engages toll-like receptor 4 (TLR4) in the vasculature to mediate adverse effects. Here, we aimed to investigate whether myeloid differentiation protein 2 (MD2), an extracellular molecule indispensable for TLR4 activation, mediates Ang II-induced vascular injury and EndMT. We utilized MD2 knockout mice and wildtype mice treated with a specific MD2 inhibitor to decipher its role in aortas of Ang II-challenged mice. To confirm our results and to provide mechanistic insights, we exposed cultured endothelial cells to Ang II, with or without MD2 silencing. We show that Ang II causes deleterious remodeling and EndMT in aortas of mice within two weeks. These Ang II effects were largely absent in MD2 knockout mice and in wildtype mice treated with a MD2 inhibitor. MD2 silencing in cultured endothelial cells confirmed the essential role of MD2 in Ang II-induced inflammatory factor induction, and EndMT-associated phenotypic change. We also found that Ang II-MD2-EndMT axis involves the activation of nuclear factor-κB. Our studies highlight an essential role of MD2 in Ang II-induced vascular inflammation and EndMT contributing to vascular injury. These results also imply that MD2 may be targeted to dampen inflammatory cardiovascular and EndMT-associated diseases. • MD2 deficiency alleviates Ang II-induced inflammation and EndMT in aortas in vivo. • Ang II-MD2-NF-κB axis induces the activation of vascular EndMT. • MD2 is a potential therapeutic target for vascular remodeling-related diseases. [ABSTRACT FROM AUTHOR]

Angiotensin II (Ang II) participates in the pathogenesis of liver injury. Our previous publications reported that myeloid differentiation protein 2 (MD2) mediates Ang II-induced cardiac and kidney inflammation by directly binding to Ang II. Thus, we hypothesize that MD2 is critical to Ang II-induced liver injury. Subcutaneous injections of Ang II for 8 weeks were adopted to build the liver injury model. With a specific MD2 inhibitor L6H21 and MD2 knockout mice, we reported that MD2 inhibition and knockout significantly mitigate liver inflammation and fibrosis in mice injected with Ang II. To be more specific, the functional and pathological damages induced by Ang II were mitigated by L6H21 or MD2 knockout. MD2 knockout or L6H21 administration inhibited the Ang II-induced upregulation of fibrosis markers, inflammatory cytokines, and adhesion molecules in gene or protein levels. The activation of NF-κB and Extracellular signal-regulated kinases (ERK) induced by Ang II was also reversed by L6H21 treatment or MD2 deficiency. Note that the co-immunoprecipitation study showed that L6H21 downregulated the ANG II-induced toll-like receptor 4 (TLR4)/MD2 complex in liver tissues while having no effects on MD2 expression. Our results reported the critical role of MD2 in the progress of liver injury and suggested that MD2 is a potential therapeutic target for liver injury. [ABSTRACT FROM AUTHOR]

Angiotensin II (Ang II) participates in the pathogenesis of liver injury. Our previous publications reported that myeloid differentiation protein 2 (MD2) mediates Ang II-induced cardiac and kidney inflammation by directly binding to Ang II. Thus, we hypothesize that MD2 is critical to Ang II-induced liver injury. Subcutaneous injections of Ang II for 8 weeks were adopted to build the liver injury model. With a specific MD2 inhibitor L6H21 and MD2 knockout mice, we reported that MD2 inhibition and knockout significantly mitigate liver inflammation and fibrosis in mice injected with Ang II. To be more specific, the functional and pathological damages induced by Ang II were mitigated by L6H21 or MD2 knockout. MD2 knockout or L6H21 administration inhibited the Ang II-induced upregulation of fibrosis markers, inflammatory cytokines, and adhesion molecules in gene or protein levels. The activation of NF-κB and Extracellular signal-regulated kinases (ERK) induced by Ang II was also reversed by L6H21 treatment or MD2 deficiency. Note that the co-immunoprecipitation study showed that L6H21 downregulated the ANG II-induced toll-like receptor 4 (TLR4)/MD2 complex in liver tissues while having no effects on MD2 expression. Our results reported the critical role of MD2 in the progress of liver injury and suggested that MD2 is a potential therapeutic target for liver injury., Competing Interests: The inventors of L6H21 agree with the publication of this article.

Angiotensin II (Ang II) induces cardiac inflammation and remodeling. Emerging evidence indicates that Ang II may utilize the Toll-like receptor 4 (TLR4) signaling pathway in mediating pro-inflammatory and pro-fibrotic activities. However, the precise mechanism is poorly understood. Myeloid differentiation 2 (MD2), a molecule that physically binds to TLR4, confers lipopolysaccharide responsiveness and may also be involved in mediating the actions of Ang II. We hypothesize that MD2 plays an essential role in cardiac inflammation and remodeling induced by local Ang II, and inhibition of MD2 can attenuate Ang II-induced cardiac dysfunction. Using a specific small molecule MD2 blocker L6H21 and the MD2 knockout mice, we show that MD2 deficiency significantly reduces cardiac inflammation and subsequent fibrosis, hypertrophy, and dysfunction in mice challenged with subcutaneous injection of Ang II. In rat cardiomyocyte-like H9c2 cells as well as rat primary cardiomyocytes, inhibition of MD2 by L6H21 or siRNA knockdown suppressed the Ang II-induced TLR4 signaling pathway activation including MyD88 recruitment, and reduced cardiomyocyte hypertrophy and matrix protein expression. These pro-inflammatory activities of Ang II were independent of the AT1 receptor. Finally, we demonstrated the direct interaction between Ang II and MD2 protein via hydrogen bonds on Arg-90, Glu-92, and Asp-100. Ang II produces an inflammatory response and cardiac remodeling by directly binding to MD2, activating MD2/TLR4 complex, and recruiting MyD88. MD2 may be a new therapeutic target for Ang II-mediated cardiac inflammation and remodeling.