Chuanping Si

Objective To study the effect of CD11b agonist leukadherin-1 (LA1) on Toll-like receptor 7 (TLR7)- and TLR9-induced activation of mouse bone marrow-derived dendritic cells (BMDCs) and its specific mechanism. Methods BMDCs were successfully induced and the concentrations of LA1 used in the study were determined by CCK-8 assay and annexin V-FITC/PI double staining. BMDCs were treated with LA1 for 2 hours followed by stimulation of TLR7 agonist R837 and TLR9 agonist CpG1826. The expression of BMDCs surface markers CD40, CD86 and MHC-II were detected by flow cytometry; IL-6, IL-12p40 and tumor necrosis factor α (TNF-α) in the cell culture supernatant were detected by ELISA; the phosphorylation of NF-κB p65 in BMDCs was detected by Western blotting. Results LA1 concentration below 20 μmol/L had no effect on the viability and apoptosis of BMDCs. LA1 pretreatment significantly inhibited R837- and CpG 1826-induced expression of CD40, CD86 and MHC-II , and the secretion of IL-6, IL-12p40 and TNF-α in BMDCs. Moreover, LA1 pretreatment significantly inhibited the phosphorylation of NF-κB p65 activated by R837 and CpG1826 in BMDCs. Conclusion CD11b agonist LA1 can significantly inhibit the activation of TLR7 and TLR9 in BMDCs by blocking the NF-κB p65 signaling pathway.

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Invasive breast cancer is highly regulated by tumor-derived cytokines in tumor microenvironment. The development of drugs that specifically target cytokines are promising in breast cancer treatment. In this study, we reported that arctigenin, a bioactive compound from Arctium lappa L., could decrease tumor-promoting cytokines GM-CSF, MMP-3, MMP-9 and TSLP in breast cancer cells. Arctigenin not only inhibited the proliferation, but also the invasion and stemness of breast cancer cells via decreasing GM-CSF and TSLP. Mechanistically, arctigenin decreased the promoter activities of GM-CSF and TSLP via reducing the nuclear translocation of NF-κB p65 which is crucial for the transcription of GM-CSF and TSLP. Furthermore, arctigenin-induced depletion of GM-CSF and TSLP inhibited STAT3 phosphorylation and β-catenin signaling resulting in decreased proliferation, invasion and stemness of breast cancer cells in vitro and in vivo. Our findings provide new insights into the mechanism by which tumor-promoting cytokines regulate breast cancer progression and suggest that arctigenin is a promising candidate for cytokine-targeted breast cancer therapy.

Summary: Asthma is a chronic inflammatory disease that involves a variety of cytokines and cells. Interleukin‐16 (IL‐16) is highly expressed during allergic airway inflammation and is involved in its development. However, its specific mechanism of action remains unclear. In the present study, we used an animal model of ovalbumin (OVA)‐induced allergic asthma with mice harboring an IL‐16 gene deletion to investigate the role of this cytokine in asthma, in addition to its underlying mechanism. Increased IL‐16 expression was observed during OVA‐induced asthma in C57BL/6J mice. However, when OVA was used to induce asthma in IL‐16^−/− mice, a diminished inflammatory reaction, decreased bronchoalveolar lavage fluid (BALF) eosinophil numbers, and the suppression of OVA‐specific IgE levels in the serum and BALF were observed. The results also demonstrated decreased levels of T helper type 2 (Th2) and Th17 cytokines upon OVA‐induced asthma in IL‐16^−/− mice. Hence, we confirmed that IL‐16 enhances the lung allergic inflammatory response and suggest a mechanism possibly associated with the up‐regulation of IgE and the promotion of Th2 and Th17 cytokine production. This work explored the mechanism underlying the regulation of IL‐16 in asthma and provides a new target for the clinical treatment of asthma.

Dysregulation of macrophage has been demonstrated to contribute to aberrant immune responses and inflammatory diseases. CD11b, expressed on macrophages, plays a critical role in regulating pathogen recognition, phagocytosis, and cell survival. In the present study, we explored the effect of leukadherin-1 (LA1), an agonist of CD11b, on regulating LPS-induced pro-inflammatory response in macrophages and endotoxic shock. Intriguingly, we found that LA1 could significantly reduce mortalities of mice and alleviated pathological injury of liver and lung in endotoxic shock. In vivo studies showed that LA1-induced activation of CD11b significantly inhibited the LPS-induced pro-inflammatory response in macrophages of mice. Moreover, LA1-induced activation of CD11b significantly inhibited LPS/IFN-γ-induced pro-inflammatory response in macrophages by inhibiting MAPKs and NF-κB signaling pathways in vitro. Furthermore, the mice injected with LA1-treated BMDMs showed fewer pathological lesions than those injected with vehicle-treated BMDMs in endotoxic shock. In addition, we found that activation of TLR4 by LPS could endocytose CD11b and activation of CD11b by LA1 could endocytose TLR4 in vitro and in vivo, subsequently blocking the binding of LPS with TLR4. Based on these findings, we concluded that LA1-induced activation of CD11b negatively regulates LPS-induced pro-inflammatory response in macrophages and subsequently protects mice from endotoxin shock by partially blocking LPS-TLR4 interaction. Our study provides a new insight into the role of CD11b in the pathogenesis of inflammatory diseases.

Summary: Interleukin‐35 (IL‐35) is a recently identified heterodimeric cytokine in the IL‐12 family. It consists of an IL‐12 subunit α chain (P35) and IL‐27 subunit Epstein–Barr virus‐induced gene 3 (EBI3) β chain. Unlike the other IL‐12 family members, it signals through four unconventional receptors: IL‐12Rβ2–IL‐27Rα, IL‐12Rβ2–IL‐12Rβ2, IL‐12Rβ2–GP130, and GP130–GP130. Interleukin‐35 signaling is mainly carried out through the signal transducer and activator of transcription family of proteins. It is secreted not only by regulatory T (Treg) cells, but also by CD8⁺ Treg cells, activated dendritic cells and regulatory B cells. It exhibits immunosuppressive functions distinct from those of other members of the IL‐12 family; these are mediated primarily by the inhibition of T helper type 17 cell differentiation and promotion of Treg cell proliferation. Interleukin‐35 plays a critical role in several immune‐associated diseases, such as autoimmune diseases and viral and bacterial infections, as well as in tumors. In this review, we summarize the structure and function of IL‐35, describe its role in immune‐related disorders, and discuss the mechanisms by which it regulates the development and progression of diseases, including inflammatory bowel disease, collagen‐induced arthritis, allergic airway disease, hepatitis, and tumors. The recent research on IL‐35, combined with improved techniques of studying receptors and signal transduction pathways, allows for consideration of IL‐35 as a novel immunotherapy target.

Immune-mediated liver injury plays a crucial role in the pathogenesis of liver diseases, which can result from viral infections, autoimmunity, alcohol intake, and drug use. Concanavalin A (Con A)-induced hepatitis is a well-characterized murine model with similar pathophysiology to that of human viral and autoimmune hepatitis. Capsaicin, a selective agonist of the transient potential vanilloid subfamily member 1 (TRPV1) receptor, exhibits anti-inflammatory effects on various causes of inflammation. In the present study, we investigated the effect of capsaicin on Con A-induced hepatitis. Capsaicin (1 mg/kg body weight) was administered by intraperitoneal injection, after which (30 minutes), the mice were challenged intravenously with Con A (20 mu g/g body weight). We collected serum for plasma transaminase analysis. Pro-inflammatory cytokine levels and hepatocyte apoptosis were assayed by ELISA and TUNEL, respectively. Liver samples were collected for real-time PCR, hematoxylin and eosin staining, and measuring oxidative stress and myeloperoxidase levels. Activation of splenocytes and hepatic mononuclear cells was analyzed by flow cytometry. Compared with control, the capsaicin-treated group showed significantly decreased aminotransferase levels and markedly prolonged mouse survival. Capsaicin pretreatment also attenuated hepatocyte apoptosis and oxidative stress. Furthermore, tumor necrosis factor-alpha and interferon-gamma levels in serum and liver were significantly suppressed, while the percentage of myeloid-derived suppressor cells increased after capsaicin pretreatment. Our findings indicate that capsaicin pretreatment protects mice from Con A-induced hepatic damage and is partially involved in inhibiting hepatocyte apoptosis, oxidative stress, and inflammatory mediators as well as regulating activation and recruitment of intrahepatic leukocytes.

Transplantation of adult human hepatic stem/progenitor cells (hHSPCs) has been considered as an alternative therapy, replacing donor liver transplantation to treat liver cirrhosis. This study assessed the antifibrotic effects of hHSPCs in mice with fibrosis induced by carbon tetrachloride (CCI4) and examined the actions of hHSPCs on the fibrogenic activity of human hepatic stellate cells (HSCs) in a coculture system. Isolated hHSPCs expressed stem/progenitor cell phenotypic markers. Mice were given CCl4 (twice weekly for 7 weeks) and hHSPC transplantation weekly. CCl4 induced advanced fibrosis (bridging fibrosis and cirrhosis) in mice, which was prevented by hHSPC transplantation. The liver of hHSPC-transplanted mice showed only occasional short septa and focal parenchymal fibrosis, and a 50% reduction in hepatic collagen, assessed by Sirius red stain histomorphometry. Moreover, the proteins for a-smooth muscle actin (alpha-SMA) and collagen I were decreased. While alpha-SMA, collagen alpha 1(I), and tissue inhibitor of metalloproproteinase-1 mRNAs were decreased, matrix metalloproteinase (MMP)-1 mRNA was increased, consistent with decreased fibrogenesis. MMP-2 and transforming growth factor-beta were not affected. Alanine aminotransferase and aspartate aminotransferase were lower, suggesting improvement of liver function/damage. In coculture, hHSPCs elicited changes of alpha-SMA and fibrogenic molecules in HSCs similar to those observed in vivo, providing evidence for a functional link between hHSPCs and HSCs. A decreased HSC proliferation was noted. Thus, transplantation of hHSPCs prevents histogenesis of advanced liver fibrosis caused by CCl4. hHSPCs mediate down-regulation of HSC activation coincident with modulation of fibrogenic molecule expression, leading to suppression of fibrogenesis both in vivo and in vitro.