Nuclear factor of activated T cells as a marker of in vivo low-dose dibenzo[a,h]anthracene exposure

We previously demonstrated that particulate matter ≤2.5 μm (PM2.5) suppresses the immune response in the spleen in vivo. Although PM2.5 includes the polycyclic aromatic hydrocarbon (PAH) such as dibenzo[a,h]anthracene (DBA), it is unclear whether PAH has a direct effect on the responses of splenocytes. In our study, the concentration of DBA used was approximately 0.8 μm , which is much lower than concentrations used in other toxicological studies of DBA. Although exposure to high concentrations of DBA is implicated in carcinogenesis, the effects of low doses of DBA on immune cells in vivo remain unclear. Here, we investigated the effects of low DBA doses on mouse splenocytes in vivo. Mice were administered dimethyl sulfoxide or DBA (0.4 or 0.8 μm ) intratracheally. Twenty-four hours after treatment, the mice were killed and their splenocytes were collected. DBA treatment enhanced mitogen-induced cell proliferation and cytokine production in the mouse splenocytes. Furthermore, DBA enhanced splenic CD4⁺ and CD8⁺ cell proliferation and cytokine production. The nuclear factor of activated T cells (NFAT) was activated in CD4⁺ cells. DBA also activated nuclear factor-kappa B and CCAAT enhancer-binding protein pathways in CD11b⁺ cells. DBA-enhanced splenocyte activation was Toll-like receptor 2-, 4-, 9- and MyD88-independent. These results suggest that NFAT represents a promising marker for evaluation of the effects of DBA on T cells and T-cell-dependent antibody responses.     

重组人白细胞介素-11对肺腺癌A549 细胞增殖、 迁移和侵袭的影响

摘要:目的 观察重组人白细胞介素-11 （rhIL-11） 对肺腺癌 A549 细胞增殖、 迁移和侵袭的影响, 并初步探讨其影响机制。方法 分别以 0、 10、 20、 50、 100 μg/L 终浓度的 rhIL-11 作用于 A549 细胞, MTT 法测定 A549 细胞增殖程度; 用 0、 10、 40、 80 μg/L 终浓度的 rhIL-11 作用于 A549 细胞, 划痕实验和 Transwell 侵袭实验测定 A549 细胞的迁移和侵袭能力; Western blot 检测基质金属蛋白酶 （MMP） -2 和 MMP-9 蛋白水平的表达。结果 rhIL-11 对 A549 细胞增殖能力无影响; rhIL-11 作用于 A549 细胞后, 细胞的迁移和侵袭能力显著增强; rhIL-11 能显著上调 MMP-2 和 MMP-9 的表达, 且表达随 rhIL-11 浓度的增高而增高 （P < 0.05）。结论 rhIL-11 能够促进 A549 细胞的迁移和侵袭, 促进 MMP-2、 MMP-9 上调为其可能的机制之一。     

Induction of cyclooxygenase-2 by staurosporine through the activation of nuclear factor for IL-6 (NF-IL6) and activator protein 2 (AP2) in an osteoblast-like cell line

The induction of cyclooxygenase-2 (COX-2) plays a crucial role in many physiological and pathological processes. The expression of the COX-2 gene is regulated by many extracellular stimuli, including growth factors, cytokines, and tumor promoters. Staurosporine, a potential anti-tumor drug, was found recently to up-regulate the expression of the COX-2 gene in the mouse osteoblast-like cell line MC3T3-E1. The ability of staurosporine to induce the expression of the COX-2 gene was investigated using luciferase reporters controlled by various COX-2 core promoter regions. Two cis-acting sites for activator protein 2 (AP2) and nuclear factor for IL-6 (NF-IL6), respectively, were identified as responsible for the staurosporine-mediated COX-2 up-regulation. Mutational analysis further verified that both NF-IL6 and AP2 are involved in this process. Further studies showed the stimulatory effect of staurosporine on luciferase activity to be both time- and concentration-dependent. Luciferase activity could be induced at as low as 5 nM staurosporine and reached a maximum at around 20 nM. At 50 nM, the stimulatory effect of staurosporine on luciferase activity reached a maximum at about 8 hr and fell rapidly following 10 hr of incubation. Interestingly, a selective protein kinase C inhibitor, 2-[1-(3-dimethylaminopropyl)indol-3-yl]-3-(indol-3-yl) maleimide (GF109203X), failed to stimulate luciferase activity under the same conditions. This finding implies that staurosporine-mediated COX-2 gene expression is specific and independent of protein kinase C activity.     

Inhibition of inflammatory mediators by polyphenolic plant extracts in human intestinal Caco-2 cells

The mitogen-activated protein kinases (MAPK) and nuclear factor κB (NF-κB) are involved in transduction cascades that play a key role in inflammatory response. We tested the ability of preselected natural polyphenolic extracts (grape seed, cocoa, sugar cane, oak, mangosteen and pomegranate) to modulate intestinal inflammation using human intestinal Caco-2 cells treated for 4 h with these extracts and then stimulated by cytokines for 24 or 48 h. The effect of polyphenolic extracts, at 50 μmol of gallic acid equivalent/l, was investigated on inflammation-related cellular events: (i) NF-κB activity (cells transfected with a NF-κB-luciferase construct), (ii) activation of Erk1/2 and JNK (western blotting), (iii) secretion of interleukin 8 (IL-8) (ELISA), (iv) secretion of prostaglandin (PG) E₂ (ELISA), (v) production of NO (Griess method). Results show that: (i) sugar cane, oak and pomegranate extracts inhibited NF-κB activity (from 1.6 to 1.9-fold) (P < 0.001); (ii) pomegranate slightly inhibited Erk1/2 activation (1.3-fold) (P = 0.008); (iii) oak and pomegranate decreased NO synthesis by 1.5-fold (P < 0.001) and that of IL-8 by 10.3 and 6.7-fold respectively; (iv) pomegranate and cocoa decreased PGE₂ synthesis by 4.6 (P < 0.0001) and 2.2-fold (P = 0.001), respectively. We suggest that pomegranate extract could be particularly promising in dietary prevention of intestinal inflammation.     

Inhibition of interleukin-8 (CXCL8/IL-8) responses by repertaxin, a new inhibitor of the chemokine receptors CXCR1 and CXCR2

Repertaxin is a new non-competitive allosteric blocker of interleukin-8 (CXCL8/IL-8) receptors (CXCR1/R2), which by locking CXCR1/R2 in an inactive conformation prevents receptor signaling and human polymorphonuclear leukocyte (PMN) chemotaxis. Given the unique mode of action of repertaxin it was important to examine the ability of repertaxin to inhibit a wide range of biological activities induced by CXCL8 in human leukocytes. Our results show that repertaxin potently and selectively blocked PMN adhesion to fibrinogen and CD11b up-regulation induced by CXCL8. Reduction of CXCL8-mediated PMN adhesion by repertaxin was paralleled by inhibition of PMN activation including secondary and tertiary granule release and pro-inflammatory cytokine production, whereas PMN phagocytosis of Escherichia coli bacteria was unaffected. Repertaxin also selectively blocked CXCL8-induced T lymphocyte and natural killer (NK) cell migration. These data suggest that repertaxin is a potent and specific inhibitor of a wide range of CXCL8-mediated activities related to leukocyte recruitment and functional activation in inflammatory sites.     

The adaptor Lnk (SH2B3): an emerging regulator in vascular cells and a link between immune and inflammatory signaling

A better knowledge of the process by which inflammatory extracellular signals are relayed from the plasma membrane to specific intracellular sites is a key step to understand how inflammation develops and how it is regulated. This review focuses on Lnk (SH2B3) a member, with SH2B1 and SH2B2, of the SH2B family of adaptor proteins that influences a variety of signaling pathways mediated by Janus kinase and receptor tyrosine kinases. SH2B adaptor proteins contain conserved dimerization, pleckstrin homology, and SH2 domains. Initially described as a regulator of hematopoiesis and lymphocyte differentiation, Lnk now emerges as a key regulator in hematopoeitic and non hematopoeitic cells such as endothelial cells (EC) moderating growth factor and cytokine receptor-mediated signaling. In EC, Lnk is a negative regulator of TNF signaling that reduce proinflammatory phenotype and prevent EC from apoptosis. Lnk is a modulator in integrin signaling and actin cytoskeleton organization in both platelets and EC with an impact on cell adhesion, migration and thrombosis. In this review, we discuss some recent insights proposing Lnk as a key regulator of bone marrow-endothelial progenitor cell kinetics, including the ability to cell growth, endothelial commitment, mobilization, and recruitment for vascular regeneration. Finally, novel findings also provided evidences that mutations in Lnk gene are strongly linked to myeloproliferative disorders but also autoimmune and inflammatory syndromes where both immune and vascular cells display a role. Overall, these studies emphasize the importance of the Lnk adaptor molecule not only as prognostic marker but also as potential therapeutic target.     

Functional modulation of CD8+ T cell by approved novel immune enhancer: Nocardia rubra Cell-Wall Skeletons (Nr-CWS)

Nocardia rubra cell wall skeleton (Nr-CWS) has been reported to have innate immunostimulating and anti-tumor activities. However, the immunomodulatory effects of Nr-CWS on CD8+ T cells and their related mechanisms are still unknown. In this work, our team purified CD8⁺T cells from spleen cells and explored the phenotype and function of NR-CWS in vitro on CD8⁺T cells. We observed that Nr-CWS can significantly up-regulate the expression of CD69 and CD25 on CD8⁺T cells, with no significant effect on apoptosis or cell death of CD8⁺T cells that occurs in vitro during culture. In addition, the effect of perforin and granzyme B was increased after Nr-CWS treatment, but did not substantially alter the expression of TRAIL and FasL. A variety of cytokine analyses have shown that of the cytokines examined (IFN-γ, TNF-α, IL-2, IL-4, IL-5, IL-6 and IL-10), only IFN-γ and TNF The increase in -α was more pronounced, and the effect of Nr-CWS in CD8⁺T cell culture medium on CD8+ T cells was independent of Th cells. Our results demonstrated that Nr-CWS could up-regulate CD69 and CD25 expression on CD8⁺T cells, promoting IFN-γ and TNF-α secretion, and enhancing perforin and granzyme B production. Thus Nr-CWS may have Immunoaugmenting therapeutic activity via an increase in CD8⁺T cells response.     

Cannabinoids increase lung cancer cell lysis by lymphokine-activated killer cells via upregulation of ICAM-1

Cannabinoids have been shown to promote the expression of the intercellular adhesion molecule 1 (ICAM-1) on lung cancer cells as part of their anti-invasive and antimetastatic action. Using lung cancer cell lines (A549, H460) and metastatic cells derived from a lung cancer patient, the present study addressed the impact of cannabinoid-induced ICAM-1 on cancer cell adhesion to lymphokine-activated killer (LAK) cells and LAK cell-mediated cytotoxicity. Cannabidiol (CBD), a non-psychoactive cannabinoid, enhanced the susceptibility of cancer cells to adhere to and subsequently be lysed by LAK cells, with both effects being reversed by a neutralizing ICAM-1 antibody. Increased cancer cell lysis by CBD was likewise abrogated when CBD-induced ICAM-1 expression was blocked by specific siRNA or by antagonists to cannabinoid receptors (CB₁, CB₂) and to transient receptor potential vanilloid 1. In addition, enhanced killing of CBD-treated cancer cells was reversed by preincubation of LAK cells with an antibody to lymphocyte function associated antigen-1 (LFA-1) suggesting intercellular ICAM-1/LFA-1 crosslink as crucial event within this process. ICAM-1-dependent pro-killing effects were further confirmed for the phytocannabinoid Δ⁹-tetrahydrocannabinol (THC) and R(+)-methanandamide (MA), a hydrolysis-stable endocannabinoid analogue. Finally, each cannabinoid elicited no significant increase of LAK cell-mediated lysis of non-tumor bronchial epithelial cells, BEAS-2B, associated with a far less pronounced (CBD, THC) or absent (MA) ICAM-1 induction as compared to cancer cells. Altogether, our data demonstrate cannabinoid-induced upregulation of ICAM-1 on lung cancer cells to be responsible for increased cancer cell lysis by LAK cells. These findings provide proof for a novel antitumorigenic mechanism of cannabinoids.     

Inhibition of leukocyte function and interleukin-2 gene expression by 2-methylarachidonyl-(2'-fluoroethyl)amide, a stable congener of the endogenous cannabinoid receptor ligand anandamide

Arachidonylethanolamide (anandamide, AEA) has been identified as an endogenous ligand for cannabinoid receptors CB1 and CB2. Characterization of the direct cannabimimetic actions of anandamide has been hampered by its short duration of action and rapid degradation in in vivo and in vitro systems to arachidonic acid, a precursor in the biosynthesis of a broad range of biologically active molecules. In the present studies, we utilized 2-methylarachidonyl-(2'-fluoroethyl)amide (F-Me-AEA), an analog of anandamide resistant to enzymatic degradation, to determine whether F-Me-AEA modulated T cell function similar to that of plant-derived cannabinoids. Indeed, F-Me-AEA at low micromolar concentrations exhibited a marked inhibition of phorbol ester plus calcium ionophore (PMA/Io)-induced IL-2 protein secretion and steady state mRNA expression. Likewise, a modest suppression of the mixed lymphocyte response was observed in the presence of F-Me-AEA indicating an alteration in T cell responsiveness to allogeneic MHC class II antigens. F-Me-AEA was also found to modestly inhibit forskolin-stimulated adenylate cyclase activity in thymocytes and splenocytes, a hallmark of cannabinoid receptor agonists. Further characterization of the influence of F-Me-AEA on the cAMP signaling cascade revealed an inhibition of CREB-1/ATF-1 phosphorylation and subsequently, an inhibition of CRE DNA binding activity. Characterization of nuclear binding proteins further revealed that NF-AT and, to a lesser extent, NF-kappaB DNA binding activities were also suppressed. These studies demonstrate that F-Me-AEA modulates T cell function in a similar manner to plant-derived and endogenous cannabinoids and therefore can be utilized as an amidase- and hydrolysis-resistant endogenous cannabinoid.     

The co-expression characteristics of LAG3 and PD-1 on the T cells of patients with breast cancer reveal a new therapeutic strategy

Many studies have shown a special interaction between LAG3 and PD-1 in T cell inhibition, while the co-expression and effect of LAG3 and PD-1 on T cells in breast cancer patients are still not very clear. Here, with strict exclusion criteria, 88 patients with breast cancer and 18 healthy controls were enrolled. The percentages of LAG3⁺PD-1⁺ T cells in their peripheral blood (PBL) and tumor infiltrating T cells (TIL) were analyzed by flow cytometry, which showed an increase in TILs but no difference in PBLs and presented differences in TILs in different molecular subtypes (P < 0.05). In triple-negative breast cancer (TNBC), the highest percentages were observed, while in ER+/PR+ breast cancer, the lowest percentages were observed; however, these percentages were not different in different clinical stages (P > 0.05). Immunohistochemical staining showed that the expression of their ligands, PD-L1, MHC class II molecular and FGL1, was inconsistent in different molecular subtypes and clinical stages. Analysis of the functions of T cells with different phenotypes showed that the proliferation and secretion capacity of LAG3⁺PD-1⁺ T cells was obviously exhausted, with more than a two-fold of decrease compared with the groups of single positive LAG3 or PD-1 (P < 0.05). Finally, in a mouse model of TNBC, the dual blockade of LAG3 and PD-1 was indicated to achieve a better anti-tumour effect than either one alone (P < 0.05), which may provide a new strategy for the immunoregulatory treatment of patients with TNBC in the future.     

Low-dose naltrexone inhibits the epithelial-mesenchymal transition of cervical cancer cells in vitro and effects indirectly on tumor-associated macrophages in vivo

The metastasis of cervical cancer has always been a clinical challenge. We investigated the effects of low-dose naltrexone (LDN) on the epithelial mesenchymal transition of cervical cancer cells in vitro as well as its influence on macrophage polarization and associated cytokines in vivo. The results suggested that LDN supressed the proliferation, migration and invasion abilities and promote their apoptosis in Hela cells, whereas the opioid growth factor receptor (OGFr) silenced significantly reversed these effects in vitro. Knockdown the expression of OGFr, the inhibitory of LDN on EMT was weakened. LDN could inhibit cervical cancer progression in nude mice. In additon, LDN indirectly reduced the number of tumor-associated macrophages (TAMs), mainly M2 macrophages, and decreased expression of anti-inflammatory factor IL-10 in the serum of nude mice. These findings demonstrate that LDN could be a potential treatment for cervical cancer.