Zhiqiang Tian

Astragalus polysaccharides protect against dextran sulfate sodium-induced colitis by inhibiting NF-κВ activation

Astragalus polysaccharide (APS) is a bioactive extract of Astragalus membranaceus (AM), which possess a wide range of medicinal benefits, including anti-inflammatory, anti-oxidative, anti-tumor and anti-diabetic effects. The present work evaluated the therapeutic effect of APS and its potential mechanisms in a mouse model of dextran sulfate sodium (DSS)-induced colitis. The APS treatment led to significant improvements in colitis disease activity index (DAI) and histological scores, as well as significantly increased weight and colon length in mice as compared to the control group. Mechanically, reduced NF-κВ DNA phosphorylation activity and downregulated TNF-α, IL-1β, IL-6, IL-17 expressions and myeloperoxidase (MPO) activity were associated with improvement in colitis observed in APS-treated mice. These findings suggest that APS may represent a natural therapeutic approach for treating inflammatory bowel disease, such as ulcerative colitis.

Antiviral effects of cyclosporine A in neonatal mice with rotavirus-induced diarrhea.

Objectives: Because rotavirus gastroenteritis is associated with high morbidity and mortality especially in developing countries, it is necessary to develop antirotavirus drugs for the treatment of rotavirus infection. Previous studies have demonstrated that cyclosporin A (CsA) has antiviral properties against rotavirus. Its effect has not yet been evaluated against rotavirus diarrheal disease. The aim of this study was to assess the anti-rotavirus efficacy of CsA in neonatal mice after induction of rotavirus diarrhea. Methods: Suckling mice were inoculated with murine rotavirus. On the onset of diarrhea, mice were given different concentrations of CsA. To evaluate the effects of CsA on reduction of rotavirus diarrhea, diarrhea score, fecal virus shedding, and pathological lesion change in the small intestine, messenger RNA (mRNA) expression levels in the small intestine and spleen of mice were measured for type I interferon (IFN-&agr; and IFN-&bgr;), inflammation-related cytokines (interleukin [IL]-8, IL-10, IFN-&ggr;, and tumor necrosis factor-&agr;), and inflammatory signaling pathways (p38, c-Jun N-terminal kinase, activator protein-1, and nuclear factor-kappa B). Results: Among virus-inoculated and CsA-treated groups, a dose of 5 mg · kg−1 · day−1 of CsA inhibited diarrhea and improved fecal virus shedding and intestinal lesion changes. IFN-&bgr; mRNA expression was significantly increased in rotavirus-induced diarrhea mice treated with 5 mg · kg−1 · day−1 of CsA, whereas the mRNA expression levels of inflammation-related cytokines (IL-8, IL-10, IFN-&ggr;, and tumor necrosis factor-&agr;) and inflammatory signaling pathways (p38, c-Jun N-terminal kinase, activator protein-1, and nuclear factor-kappa B) were markedly decreased. Antiviral effects of CsA were dose dependent. Conclusions: CsA can inhibit rotavirus infection in neonatal mice through its antiviral properties. The mechanism for this may be through CsA suppression of inflammation by viral inhibition in animal models.

Astagalus Polysaccharide Attenuates Murine Colitis through Inhibiton of the NLRP3 Inflammasome.

Astragalus polysaccharide is an important bioactive component of Astragalus membranaceus, an herb used in traditional Chinese medicine for treating inflammatory bowel disease. The NOD-like receptor protein 3 inflammasome plays an important role in the pathogenesis of inflammatory bowel disease. However, little is known about the role of NOD-like receptor protein 3 inflammasome in Astragalus polysaccharide-treated mice with experimental colitis. For this study, we investigated the molecular mechanisms that underlie the treatment of inflammatory bowel disease by Astragalus polysaccharide. We show that Astragalus polysaccharide treatment reduces the disease activity index and histological injury scores compared to the colitis model group. Astragalus polysaccharide also effectively inhibited the expression of NOD-like receptor protein 3, apoptotic speck protein containing a c-terminal caspase recruitment domain, caspase-1, interleukin-18, and interleukin-1β, as shown by quantificational RT-PCR or the enzyme-linked immunosorbent assay. Furthermore, Astragalus polysaccharide treatments produced significant dose-dependent improvements in dextran sulfate sodium-induced experimental colitis. Our data provide the reliable evidence that Astragalus polysaccharide is able to exert a therapeutic effect in dextran sulfate sodium-induced colitis by inhibiting the activation of the NOD-like receptor protein 3 inflammasome, which acts to decrease the production of inflammatory factors such as interleukin-18 and interleukin-1β.

Lycium barbarum polysaccharide attenuates type II collagen-induced arthritis in mice

No curative treatment is yet available for rheumatoid arthritis (RA), wherein chronic synovitis progresses to cartilage and bone destruction. Considering the recently recognized anti-inflammatory properties of Lycium barbarum polysaccharide (LBP; a derivative of the goji berry), we established the collagen type II-induced arthritis (CIA) mouse model to investigate the potential therapeutic effects and mechanisms of LBP. The CIA-induced changes and LBP-related effects were assessed by micro-computed tomography measurement of bone volume/tissue volume and by ELISA and western blotting detection of inflammatory mediators and matrix metalloproteinases (MMPs). The CIA mice showed substantial bone damage, bone loss, and increased concentrations of TNF-α, IL-6, IL-17, PGE2, MIP-1, anti-type II collagen IgG, MMP-1, and MMP-3. LBP treatments produced significant dose-dependent improvements in CIA-induced bone damage and bone loss, and significantly reduced CIA-stimulated expression of the inflammatory mediators and MMPs. Thus, LBP therapy can preserve bone integrity in CIA mice, possibly through down-regulation of inflammatory mediators.

Looped Host Defense Peptide CLP-19 Binds to Microtubules and Inhibits Surface Expression of TLR4 on Mouse Macrophages

The looped host defense peptide CLP-19 is derived from a highly functional core region of the Limulus anti-LPS factor and exerts robust anti-LPS activity by directly interacting with LPS in the extracellular space. We previously showed that prophylactic administration of CLP-19 even 20 h prior to LPS challenge might significantly increase the survival rate in a lethal endotoxin shock mouse model. Such an effect may be associated with immune regulation of CLP-19. To investigate the underlying mechanisms, peptide affinity chromatography, immunofluorescence, and Western blotting procedures were used to identify α- and β-tubulin as direct and specific binding partners of CLP-19 in the mouse macrophage cell line RAW 264.7. Bioinformatic analysis using the AutoDock Vina molecular docking and PyMOL molecular graphics system predicted that CLP-19 would bind to the functional residues of both α- and β-tubulin and would be located within the groove of microtubules. Tubulin polymerization assay revealed that CLP-19 might induce polymerization of microtubules and prevent depolymerization. The immunoregulatory effect of CLP-19 involving microtubules was investigated by flow cytometry, immunofluorescence, and Western blotting, which showed that CLP-19 prophylactic treatment of RAW 264.7 cells significantly inhibited LPS-induced surface expression of TLR4. Taken together, these results suggest that CLP-19 binding to microtubules disrupts the dynamic equilibrium of microtubules, reducing the efficacy of microtubule-dependent vesicular transport that would otherwise translocate TLR4 from the endoplasmic reticulum to the cell surface.

Sodium chloride exacerbates dextran sulfate sodium-induced colitis by tuning proinflammatory and antiinflammatory lamina propria mononuclear cells through p38/MAPK pathway in mice

AIM To investigate the influence of high salt on dextran sulfate sodium (DSS)-induced colitis in mice and explore the underlying mechanisms of this effect. METHODS DSS and NaCl were used to establish the proinflammatory animal model. We evaluated the colitis severity. Flow cytometry was employed for detecting the frequencies of Th1, macrophages and Tregs in spleen, mesenteric lymph node and lamina propria. The important role of macrophages in the promotion of DSS-induced colitis by NaCl was evaluated by depleting macrophages with clodronate liposomes. Activated peritoneal macrophages and lamina propria mononuclear cells (LPMCs) were stimulated with NaCl, and proteins were detected by western blotting. Cytokines and inflammation genes were analyzed by enzyme-linked immunosorbent assay and RT-PCR, respectively. RESULTS The study findings indicate that NaCl up-regulates the frequencies of CD11b+ macrophages and CD4+IFN-γ+IL-17+ T cells in lamina propria in DSS-treated mice. CD3+CD4+CD25+Foxp3+ T cells, which can secrete high levels of IL-10 and TGF-β, increase through feedback in NaCl- and DSS-treated mice. Furthermore, clodronate liposomes pretreatment significantly alleviated DSS-induced colitis, indicating that macrophages play a vital role in NaCl proinflammatory activity. NaCl aggravates peritoneal macrophage inflammation by promoting the expressions of interleukin (IL)-1, IL-6 and mouse inducible nitric oxide synthase. Specifically, high NaCl concentrations promote p38 phosphorylation in lipopolysaccharide- and IFN-γ-activated LPMCs mediated by SGK1. CONCLUSION Proinflammatory macrophages may play an essential role in the onset and development of NaCl-promoted inflammation in DSS-induced colitis. The underlining mechanism involves up-regulation of the p38/MAPK axis.

Synergistic antibiotic effect of looped antimicrobial peptide CLP-19 with bactericidal and bacteriostatic agents

The treatment of drug-resistant infections is complicated and the alarming rise in infectious diseases poses a unique challenge for development of effective therapeutic strategies. Antibiotic-induced liberation of the bacterial endotoxin lipopolysaccharide (LPS) may have immediate adverse effects promoting septic shock in patients. In the present study, we first confirmed our previous finding that looped antimicrobial peptide CLP-19 exerts non-specific direct antibacterial activity with no toxic to mammalian cells and second revealed that CLP-19 has synergistic effect to enhance the antibacterial activities of other conventional bactericidal (ampicillin and ceftazidime) and bacteriostatic (erythromycin and levofloxacin) agents. Third, the underlying mechanism of antibiotic effect was likely associated with stimulation of hydroxyl radical generation. Lastly, CLP-19 was shown to effectively reduce the antibiotic-induced liberation of LPS, through direct neutralization of the LPS. Thus, CLP-19 is a potential therapeutic agent for combinatorial antibiotic therapy.The treatment of drug-resistant infections is complicated and the alarming rise in infectious diseases poses a unique challenge for development of effective therapeutic strategies. Antibiotic-induced liberation of the bacterial endotoxin lipopolysaccharide (LPS) may have immediate adverse effects promoting septic shock in patients. In the present study, we first confirmed our previous finding that looped antimicrobial peptide CLP-19 exerts non-specific direct antibacterial activity with no toxic to mammalian cells and second revealed that CLP-19 has synergistic effect to enhance the antibacterial activities of other conventional bactericidal (ampicillin and ceftazidime) and bacteriostatic (erythromycin and levofloxacin) agents. Third, the underlying mechanism of antibiotic effect was likely associated with stimulation of hydroxyl radical generation. Lastly, CLP-19 was shown to effectively reduce the antibiotic-induced liberation of LPS, through direct neutralization of the LPS. Thus, CLP-19 is a potential therapeutic agent for combinatorial antibiotic therapy.

Critical Role of Alternative M2 Skewing in miR-155 Deletion-Mediated Protection of Colitis

Inflammatory bowel disease (IBD) is associated with dysregulation of both innate and adaptive immune response in the intestine. MicroRNA (miR)-155 is frequently expressed and functions in many immune cell types. Besides its function in adaptive immunity, miR-155 is a key regulator of the innate immune response in macrophages, dendritic cells, and even in epithelia cells. Although the roles of miR-155 within T and B lymphocytes in colitis have been reported, its function in innate immune cells has not been thoroughly examined. In this study, the dextran sulfate sodium (DSS)-induced colitis model was established in wild-type (WT) and miR-155−/− mice. Our results showed that miR-155 deficiency in macrophages recapitulated the alleviated colitis feature of miR-155−/− mice and appeared to skew toward the alterative M2 phenotype. Notably, the predominance of M2 in colon can result in dampened intestinal immune cell proliferation and inhibit CD4 T cell polarization toward Th1 and Th17. Moreover, C/EBPβ and SOCS1 were demonstrated as two key functional targets in this process. We also provided evidence for use of miR-155 inhibitor to treat colitis. Collectively, the findings highlight the central role of alternative M2 skewing for miR-155 function in colitis and reveal that macrophages might be a main target for therapeutics.

Looped limulus anti-lipopolysaccharide derived peptide CLP-19 induces endotoxin tolerance involved inhibition of NF-κB activation

Endotoxin tolerance (ET) is a complex protective mechanism against endotoxin shock. The looped CLP-19 peptide derived from Limulus anti-LPS peptide induced the ET phenomenon but the molecular mechanism has yet to be fully elucidated. Here, we confirmed that CLP-19 attenuated upon LPS stimulated pro-inflammatory factor secretion of TNF-α and IL-6 but increased anti-inflammatory factor production of IL-10 in dose- and time-dependent manners. CLP-19 also inhibited subsequent LPS stimulated expression of TLR4 on the cell membrane. Moreover, the CLP-19 inhibited degradation of the inhibitor of NF-κB (IκBα and IκBβ) and reduced LPS induced NF-κB activity, but not of effects on expression of MyD88 and TRAF-6. Finally CLP-19 significantly increased survival of lethal LPS shock mouse models with significantly less pathological injury to lung. These findings collectively suggest that CLP-19 induces ET phenomenon involved inhibition of NF-κB activation. In conclusion, this study has revealed a novel function of CLP-19 that appears to represent a potential therapeutic agent for clinical treatment of septic shock.