Indirubin-3'-(2,3 dihydroxypropyl)-oximether (E804) is a potent modulator of LPS-stimulated macrophage functions

Daqing formula ameliorated allergic asthma and airway dysbacteriosis in mice challenged with ovalbumin and ampicillin

ETHNOPHARMACOLOGICAL RELEVANCE

Asthma is a chronic airway inflammatory disease that can lead to several complications caused by bacterial infections. However, recurrent attacks of the disease require long-term use of antibiotics, resulting in lung dysbiosis and poor outcomes. Daqing Formula (DQF) is a well-known herbal medicine in Pharmacopoeia of China, which is widely used for various stimuli-induced lower respiratory diseases, including asthma, bronchitis, and pneumonia. Thus, it has been demonstrated to be a plant-derived broad-spectrum antibiotic for treating and preventing various acute and chronic respiratory diseases.

AIM OF THE STUDY

This study evaluated the efficacy and possible mechanism of DQF on allergic asthma and airway dysbiosis.

METHODS AND MATERIALS

The mice were co-challenged with ovalbumin and ampicillin to induce allergic asthma combined with airway dysbacteriosis. The populations of lung microbiota were detected by using 16s DNA sequencing. The levels of asthmatic markers in BALF were detected by ELISA. The levels of Th1/Th2 cytokines in splenic CD4+ cells of mice were analyzed by flow cytometry. The expressions of the GSK-3β signaling pathway in the lung tissues of asthmatic mice and eosinophils were detected by western blotting assay. The inhibition of DQF on the production of pro-inflammatory cytokines in eosinophils of asthmatic mice.

RESULTS

The results showed that treatment with DQF at 200-800 mg/kg doses significantly reduced the frequency of nasal rubbing and lung inflammation as well as the number of total cells, eosinophils, and macrophages in bronchoalveolar lavage fluid. It decreased the relative abundances of Streptococcus, Cuoriavidus, and Moraxella, increased Akkermansia and Prevotella_6 in lung tissues of asthmatic mice, and inhibited the growth of Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae and their resistant strains in vitro. Furthermore, DQF reduced the levels of eotaxin, TSLP, IL-4, IL-5, IL-25, and IL-33, but enhanced IFN-γ and IL-12 in BALF. It elevated the population of Th1 cells, inhibited eosinophil activation, and downregulated the expressions of p-GSK-3β, p-p65, nuclear β-catenin, and p-STAT3 in the lung tissues of asthmatic mice.

CONCLUSIONS

The results revealed that DQF reduced airway inflammation, ameliorated lung dysbiosis, shifted the Th1/Th2 balance, and inhibited eosinophil activation in asthmatic mice, indicating its potential for severe asthma treatment.

PPRX-1701, a nanoparticle formulation of 6'-bromoindirubin acetoxime, improves delivery and shows efficacy in preclinical GBM models

Derivatives of the Chinese traditional medicine indirubin have shown potential for the treatment of cancer through a range of mechanisms. This study investigates the impact of 6'-bromoindirubin-3'-acetoxime (BiA) on immunosuppressive mechanisms in glioblastoma (GBM) and evaluates the efficacy of a BiA nanoparticle formulation, PPRX-1701, in immunocompetent mouse GBM models. Transcriptomic studies reveal that BiA downregulates immune-related genes, including indoleamine 2,3-dioxygenase 1 (IDO1), a critical enzyme in the tryptophan-kynurenine-aryl hydrocarbon receptor (Trp-Kyn-AhR) immunosuppressive pathway in tumor cells. BiA blocks interferon-γ (IFNγ)-induced IDO1 protein expression in vitro and enhances T cell-mediated tumor cell killing in GBM stem-like cell co-culture models. PPRX-1701 reaches intracranial murine GBM and significantly improves survival in immunocompetent GBM models in vivo. Our results indicate that BiA improves survival in murine GBM models via effects on important immunotherapeutic targets in GBM and that it can be delivered efficiently via PPRX-1701, a nanoparticle injectable formulation of BiA.

Pharmacological properties of indirubin and its derivatives

BACKGROUND

Indirubin is the main bioactive component of the traditional Chinese medicine Indigo naturalis and is a bisindole alkaloid. Multiple studies have shown that indirubin exhibits good anticancer, anti-inflammatory and neuroprotective properties.

METHODS

The purpose of this review is to provide a summary of the pharmacological mechanisms of indirubin and its derivatives.

RESULTS

Indirubin and its derivatives exert anticancer effects by regulating the expression of cyclin-dependent kinases (CDKs), GSK-3β, Bax, Bcl-2, C-MYC, matrix metalloproteinases (MMPs), and focal adhesion kinase (FAK) through the PI3K/AKT/mTOR, nuclear factor (NF)-κB, mitogen-activated protein kinase (MAPK), JAK/signal transducer and activator of transcription 3 (STAT3) pathways and other signaling pathways. We also reviewed the anti-inflammatory and neuroprotective properties of indirubin and its derivatives.

CONCLUSION

The findings of recent studies assessing indirubin and its derivatives suggest that these compounds can be used as potential drugs to treat tumors, inflammation, neuropathy and bacterial infection.

The In Vitro Proinflammatory Properties of Water Accommodated Sediment Extracts from a Creosote-Contaminated US Environmental Protection Agency Superfund Site

The southern branch of the Elizabeth River near Portsmouth, Virginia, USA, is one of the most creosote-polluted subestuaries in North America and the former location of the Atlantic Wood US Environmental Protection Agency Superfund site. We previously demonstrated that adult Atlantic Wood killifish collected in situ had severe hepatic lesions, including hepatoblastoma and hepatocellular carcinoma, as well as suppressed circulating antibody responses compared to a historical reference site. Moreover, several innate immune functions were higher in Atlantic Wood fish, including elevated expression of hepatic cyclooxygenase-2 (COX-2), suggesting a proinflammatory environment. To further examine the potential of Atlantic Wood contaminants to modulate innate immune function(s), the present study used RAW264.7 mouse macrophages as an in vitro model to develop new approach methodologies for rapid screening. Lipopolysaccharide (LPS)-stimulated nitric oxide secretion by macrophages is a rapid, sensitive, and predictive in vitro system for screening potentially immunotoxic contaminants as single compounds or as complex mixtures. Compared to the reference site, filter-sterilized Atlantic Wood sediment extracts (water accommodated fractions) induced nitric oxide and IL-6 secretion as well as inducible nitric oxide synthase and COX-2 proteins at levels comparable to or higher than those induced by LPS treatments alone. Extracts also increased phagocytic activity by macrophages. Using a limulus lysate assay, we show that bacterial endotoxin levels in Atlantic Wood extracts are higher than in reference extracts and that polymyxin-B chelation ameliorates proinflammatory effects. These findings illuminate the reality of sediment constituents other than toxic compounds previously associated with developmental abnormalities and carcinogenesis in killifish from the Atlantic Wood site. Perhaps these data also suggest the presence of contaminant-adapted consortia of sediment microbes at many heavily polluted sites worldwide compared to less contaminated sites. Environ Toxicol Chem 2021;40:1576-1585. © 2021 SETAC.

Evaluation of the Developmental Toxicity Induced by E804 in Zebrafish Embryos

E804, a derivative of indirubin, have multi-biological activities such as anticancer and anti-inflammatory activities, but little is known about its developmental toxicity. In this study, we investigated the toxicity of E804 on the developments of zebrafish embryos. Our results showed that E804 treatment caused a significant increase of the malformation rate compared with the control groups. Pericardial edema and curved body shape were the most morphological abnormalities observed in E804-treated group. The hatching rates and body length of the zebrafish larvae was significantly decreased in E804-treated groups. E804 also affect the development of heart, liver, phagocytes and vascular formation. Further studies showed that the level of reactive oxygen species was significantly increased. The activity of total superoxide dismutase decreased and the concentration of malondialdehyde were increased. Much more apoptotic cells were detected in E804-treated group, compared with the control. In addition, gene-expression results showed that the pathways of oxidative stress and apoptosis were provoked in E804 treated groups. Taken together, our findings will be helpful to understanding E804-induced developmental toxicity and the underlying mechanism.

Modulation of glioma-inflammation crosstalk profiles in human glioblastoma cells by indirubin-3'-(2,3 dihydroxypropyl)-oximether (E804) and 7-bromoindirubin-3'-oxime (7BIO)

Indirubins E804 (indirubin-3'-(2,3 dihydroxypropyl)-oximether) and 7BIO (7-Bromoindirubin-3'-oxime) are synthetic derivatives of natural indirubin, the active compound in Danggui Longhui Wan, a traditional Chinese remedy for cancer and inflammation. Herein, we explore E804 and 7BIO for their potential to modulate key pro-inflammatory genes and cytokines in LN-18 and T98G glioblastoma cells. High grade gliomas typically secrete large amounts of inflammatory cytokines and growth factors that promote tumor growth in an autocrine fashion. Inflammation is emerging as a key concern in the success of new treatment modalities for glioblastomas. Studies indicate that select indirubin derivatives bind and activate signaling of the AHR pathway, as well as inhibit cyclin-dependent kinases and STAT3 signaling. AHR signaling is involved in hematopoiesis, immune function, cell cycling, and inflammation, and thus may be a possible target for glioma treatment. To determine the significance of the AHR pathway in LN-18 and T98G glioma inflammatory profiles, and on the effects of E804 and 7BIO on these profiles, we used 6,2',4'-trimethoxyflavone (TMF), a putative selective AHR antagonist. It was confirmed that E804 and 7BIO activates the AHR leading to cyp1b1 expression, and that TMF antagonizes expression. We then employed a commercial cancer inflammation and immunity crosstalk qRT-PCR array to screen for anti-inflammatory related properties. TMF alone inhibited expression of ifng, ptsg2, il12b, tnfa, il10, il13, the balance between pd1 and pdl1, and even expression of mhc1a/b. E804 was very potent in suppressing many pro-inflammatory genes, including il1a, il1b, il12a, ptgs2, tlr4, and others. E804 also affected expression of il6, vegfa, and stat3. Conversely, 7BIO induced cox2, but suppressed a different selection of pro-inflammatory genes including nos2, tnfa, and igf1. Secretion of IL-6 protein, an iconic inflammatory cytokine, was decreased by E804. VEGF (vascular endothelial growth factor) protein secretion was upregulated by 7BIO, yet downregulated by E804 and E804 plus TMF. Thus, E804 is both an AHR ligand and regulator of important pro-inflammatory cytokines such as IL-6 and oncogene STAT3, among others. Our results point to the use of E804 and TMF in combination as a promising new treatment for glioblastoma.

Autophagy counters LPS-mediated suppression of lysozyme

Impaired Paneth cell expression of antimicrobial protein (AMP) lysozyme is found in patients with Crohn's disease with the autophagy gene ATG16L1 risk allele, in mice with mutations in autophagy genes Atg16L1, Atg5 and Atg7, and in Irgm1 knockout mice. Defective autophagy is also associated with expansion of resident Gram-negative bacteria in the intestinal lumen. These findings suggest that autophagy may control extracellular resident microbes by governing expression of lysozyme. To test the hypothesis that autophagy may have a defensive role in host response to resident extracellular microbes, we investigated the relationship between gut microbes, autophagy, and lysozyme. RAW 264.7 macrophages were treated with fecal slurry (FS), representing the resident microbial community; lipopolysaccharide (LPS); or butyrate, representing microbial products; or a representative resident Gram-negative bacterium Desulfovibrio vulgaris (DSV). FS, LPS, and DSV inhibited lysozyme expression, whereas butyrate had no effect. Induction of autophagy by rapamycin countered this inhibition, whereas silencing of the autophagy gene Irgm1 exacerbated the inhibitory effects of LPS on lysozyme expression. LPS also inhibited lysozyme activity against DSV and autophagy reversed this effect. Our results provide a novel insight into an interaction between gut bacteria, autophagy and AMP whereby autophagy may defend the host by countering the suppression of antimicrobial protein by Gram-negative bacteria.

Emu Oil Reduces LPS-Induced Production of Nitric Oxide and TNF-α but not Phagocytosis in RAW 264 Macrophages

Emu is the second-largest extant bird native to Australia. Emu oil, obtained from the emu's fat deposits, is used as an ingredient in cosmetic skincare products. Emu oil has been reported to improve several inflammatory symptoms; however, the mechanisms of these anti-inflammatory effects are largely unknown. This study investigated the effects of emu oil on the inflammatory macrophage response in vitro. A murine macrophage cell line, RAW 264, was incubated in culture media supplemented with or without emu oil and stimulated with lipopolysaccharide (LPS). We determined phagocytic activity by measuring the number of fluorescent microspheres taken up by the cells. The phagocytic activity of RAW 264 cells in the presence of LPS was unaffected by emu oil. We also determined production of nitric oxide (NO) and tumor necrosis factor (TNF)-α in the culture medium using the Griess reaction and an enzyme-linked immunosorbent assay, respectively, and the protein expression of inducible NO synthase (iNOS) using western blotting. The results indicated that emu oil reduced the LPS-induced production of NO, TNF-α, and iNOS expression in a dose-dependent manner. The results suggested that emu oil does not reduce the phagocytic clearance rate of inflammatory matter; however, it does reduce the production of NO and TNF-α in macrophages. These latter products enhance the inflammatory response and emu oil thereby demonstrated anti-inflammatory properties.

Design, synthesis and biological evaluation of novel indolin-2-ones as potent anticancer compounds

The indolin-2-one core is a privileged structure for antitumor agents, especially kinase inhibitors. Twenty-three novel indolin-2-ones were designed by molecular dissection of the anticancer drug indirubin. Seventeen of them exhibited significant inhibition against the tested cell lines, and two of them (1c and 1h) showed IC₅₀ values at the submicromolar level against HCT-116 cells. Compounds 1c and 2c were also potent inhibitors of the triple-negative breast cancer (TNBC) cell line MDA-MB-231. Flow cytometry was utilized to explore the antitumor mechanism of 1c and 2c with MDA-MB-231 cells, and distinct effects were observed on 2c. Furthermore, immunocytochemical examination of 1c suggested a destabilization of microtubules, which was significantly different from the effect of IM, an indirubin derivative.

Anti-inflammatory effects of indirubin derivatives on influenza A virus-infected human pulmonary microvascular endothelial cells

Influenza A virus (IAV) poses global threats to human health. Acute respiratory distress syndrome and multi-organ dysfunction are major complications in patients with severe influenza infection. This may be explained by the recent studies which highlighted the role of the pulmonary endothelium as the center of innate immune cells recruitment and excessive pro-inflammatory cytokines production. In this report, we examined the potential immunomodulatory effects of two indirubin derivatives, indirubin-3′-(2,3-dihydroxypropyl)-oximether (E804) and indirubin-3′-oxime (E231), on IAV (H9N2) infected-human pulmonary microvascular endothelial cells (HPMECs). Infection of H9N2 on HPMECs induced a high level of chemokines and cytokines production including IP-10, RANTES, IL-6, IFN-β and IFN-γ1. Post-treatment of E804 or E231 could significantly suppress the production of these cytokines. H9N2 infection rapidly triggered the activation of innate immunity through phosphorylation of signaling molecules including mitogen-activated protein kinases (MAPKs) and signal transducer and activator of transcription (STAT) proteins. Using specific inhibitors or small-interfering RNA, we confirmed that indirubin derivatives can suppress H9N2-induced cytokines production through MAPKs and STAT3 signaling pathways. These results underscore the immunomodulatory effects of indirubin derivatives on pulmonary endothelium and its therapeutic potential on IAV-infection.

3,4-Dihydroxy-benzohydroxamic acid (Didox) suppresses pro-inflammatory profiles and oxidative stress in TLR4-activated RAW264.7 murine macrophages

Didox (3,4-dihydroxy-benzohydroxamic acid), is a synthetic ribonucleotide reductase (RR) inhibitor derived from polyhydroxy-substituted benzohydroxamic acid, and originally developed as an anti-cancer agent. Some studies indicate that didox may have anti-oxidative stress-like properties, while other studies hint that didox may have anti-inflammatory properties. Using nitric oxide production in response to LPS treatment as a sensitive screening assay for anti-inflammatory compounds, we show that didox is very potent at levels as low as 6.25 μM, with maximal inhibition at 100 μM. A qRT-PCR array was then employed to screen didox for other potential anti-inflammatory and anti-oxidative stress-related properties. Didox was very potent in suppressing the expression of these arrayed mRNA in response to LPS, and in some cases didox alone suppressed expression. Using qRT-PCR as a follow up to the array, we demonstrated that didox suppresses LPS-induced mRNA levels of iNOS, IL-6, IL-1, TNF-α, NF-κβ (p65), and p38-α, after 24h of treatment. Treatment with didox also suppresses the secretion of nitric oxide, IL-6, and IL-10. Furthermore, oxidative stress, as quantified by intracellular ROS levels in response to macrophage activators LPS and phorbol ester (PMA), and the glutathione depleting agent BSO, is reduced by treatment with didox. Moreover, we demonstrate that nuclear translocation of NF-κβ (p65) in response to LPS is inhibited by didox. These findings were supported by qRT-PCR for oxidative stress genes SOD1 and catalase. Overall, this study supports the conclusion that didox may have a future role in managing acute and chronic inflammatory diseases and oxidative stress due to high production of ROS.

Discovery of novel indirubin-3'-monoxime derivatives as potent inhibitors against CDK2 and CDK9

Indirubin-3'-monoxime (IM) is a potent cyclin-dependent kinase (CDK) inhibitor. Twenty novel IM derivatives were prepared to investigate the structure-activity relationships (SAR) of this compound class. Six compounds showed significant inhibition against both CDK2/cyclin E1 and CDK9/cyclin T1. The most potent compound 7t exhibited IC50 values at submicromolar level. Preliminary SAR trends were suggested and cytotoxicity of these compounds was investigated. Molecular docking studies on compounds 7l and 7t provided conducive clues for further structural optimization.

Dynamic modulation of innate immune response by varying dosages of lipopolysaccharide (LPS) in human monocytic cells

Innate monocytes and macrophages can be dynamically programmed into distinct states depending upon the strength of external stimuli. Innate programming may bear significant relevance to the pathogenesis and resolution of human inflammatory diseases. However, systems analyses with regard to the dynamic programming of innate leukocytes are lacking. In this study, we focused on the dynamic responses of human promonocytic THP-1 cells to lipopolysaccharide (LPS). We observed that varying dosages of LPS differentially modulate the expression of selected pro- and anti- inflammatory mediators such as IL-6 and IL-33. Super-low dosages of LPS preferentially induced the pro-inflammatory mediator IL-6, while higher dosages of LPS induced both IL-6 and IL-33. Mechanistically, we demonstrated that super-low and high doses of LPS cause differential activation of GSK3 and Akt, as well as the transcription factors FoxO1 and CREB. Inhibition of GSK3 enabled THP-1 cells to express IL-33 when challenged with super-low dose LPS. On the other hand, activation of CREB with adenosine suppressed IL-6 expression. Taken together, our study reveals a dynamic modulation of monocytic cells in response to varying dosages of endotoxin, and may shed light on our understanding of the dynamic balance that controls pathogenesis and resolution of inflammatory diseases.