Inhibition of CXCL12-mediated chemotaxis of Jurkat cells by direct immunotoxicants

STING inhibitor ameliorates LPS-induced ALI by preventing vascular endothelial cells-mediated immune cells chemotaxis and adhesion

Acute lung injury (ALI) is a common and devastating clinical disorder featured by excessive inflammatory responses. Stimulator of interferon genes (STING) is an indispensable molecule for regulating inflammation and immune response in multiple diseases, but the role of STING in the ALI pathogenesis is not well elucidated. In this study, we explored the molecular mechanisms of STING in regulating lipopolysaccharide (LPS)-induced lung injury. Mice were pretreated with a STING inhibitor C-176 (15, 30 mg/kg, i.p.) before LPS inhalation to induce ALI. We showed that LPS inhalation significantly increased STING expression in the lung tissues, whereas C-176 pretreatment dose-dependently suppressed the expression of STING, decreased the production of inflammatory cytokines including TNF-α, IL-6, IL-12, and IL-1β, and restrained the expression of chemokines and adhesion molecule vascular cell adhesion protein-1 (VCAM-1) in the lung tissues. Consistently, in vitro experiments conducted in TNF-α-stimulated HMEC-1cells (common and classic vascular endothelial cells) revealed that human STING inhibitor H-151 or STING siRNA downregulated the expression levels of adhesion molecule and chemokines in HMEC-1cells, accompanied by decreased adhesive ability and chemotaxis of immunocytes upon TNF-α stimulation. We further revealed that STING inhibitor H-151 or STING knockdown significantly decreased the phosphorylation of transcription factor STAT1, which subsequently influenced its binding to chemokine CCL2 and adhesive molecule VCAM-1 gene promoter. Collectively, STING inhibitor can alleviate LPS-induced ALI in mice by preventing vascular endothelial cells-mediated immune cell chemotaxis and adhesion, suggesting that STING may be a promising therapeutic target for the treatment of ALI.

Mannan Oligosaccharide Could Attenuate Ochratoxin A-Induced Immunosuppression with Long-Time Exposure Instead of Immunostimulation with Short-Time Exposure

Our previous study showed that ochratoxin A (OTA), one of the most common mycotoxins in feed, could induce immunosuppression with long-time exposure but immunostimulation with short-time exposure. However, limited studies for the control of OTA-induced two-way immune toxicity were carried out. This study explored the effects of mannan oligosaccharide (MOS), a glucomannoprotein complex with immunoregulatory capability derived from the yeast cell wall, on OTA-induced immune toxicity and its underlying mechanisms. Surprisingly, the results showed that MOS significantly attenuated immunosuppression induced by long-time OTA treatment but did not provide protection against immunostimulation induced by short-time OTA treatment on porcine alveolar macrophages (PAMs), as demonstrated by the expressions of inflammatory cytokines and the capability of migration and phagocytosis. Further, MOS increased the OTA-inhibited autophagy level and the JNK phosphorylation level on PAMs with long-time OTA treatment. In addition, the inhibition of autophagy by 3-MA or the inhibition of JNK phosphorylation by SP600125 could partly block the protective effects of MOS on OTA-induced immunosuppression. Importantly, the inhibition of JNK phosphorylation down-regulated the MOS-promoted autophagy level. In conclusion, MOS could attenuate OTA-induced immunosuppression with short-time exposure on PAMs through activating JNK-mediated autophagy but had no significant effects on OTA-induced immunostimulation with short-time exposure. Our study provides new insights into the application of MOS as an immunoregulator against mycotoxin-induced immune toxicity.

In vitro co-culture model of human monocyte-derived dendritic cells and T cells to evaluate the sensitization of dinitrochlorobenzene

Exposure to sensitizer has been suggested to be hazardous to human health, evaluation the sensitization of sensitizer is particularly important and urgently needed. Dendritic cells (DCs) exert an irreplaceable function in immunity, and the T cell receptor (TCR) repertoire is key to ensuring immune response to foreign antigens. We hypothesized that a co-culture model of human monocyte-derived dendritic cells (Mo-DCs) and T cells could be employed to evaluate the sensitization of DNCB. An experimental model of DNCB-induced sensitization in rat was employed to examine alterations of cluster of differentiation CD103⁺ DCs and T cells. A co-cultured model of Mo-DCs and T cells was developed in vitro to assess the sensitization of DNCB through the phenotypic and functional alterations of Mo-DCs, as well as the TCR repertoire. We found that the CD103⁺ DCs phenotype and T-helper (Th) cells polarization altered in sensitization rats. In vitro, phenotypic alteration of Mo-DCs caused by DNCB were consistent with in vivo results, antigen uptake capacity of Mo-DCs diminished and capacity of Mo-DCs to prime T cell increased. Clones of the TCR repertoire and the diversity of TCR repertoire were enhanced, changes were noted in the usage of variable, joining, and variable-joining gene combinations. DNCB exposure potentiated alterations and characteristics of Mo-DCs and the TCR repertoire in a co-culture model. Such changes provided innovative ideas for evaluating sensitization of DNCB.

Tributyltin Oxide Exposure During in vitro Maturation Disrupts Oocyte Maturation and Subsequent Embryonic Developmental Competence in Pigs

Tributyltin oxide (TBTO), an organotin compound, has been demonstrated to have toxic effects on several cell types. Previous research has shown that TBTO impairs mouse denuded oocyte maturation. However, limited information is available on the effects of TBTO exposure on livestock reproductive systems, especially on porcine oocytes in the presence of dense cumulus cells. In the present research, we evaluated the effects of TBTO exposure on porcine oocyte maturation and the possible underlying mechanisms. Porcine cumulus-oocyte complexes were cultured in maturation medium with or without TBTO for 42 h. We found that TBTO exposure during oocyte maturation prevented polar body extrusion, inhibited cumulus expansion and impaired subsequent blastocyst formation after parthenogenetic activation. Further analysis revealed that TBTO exposure not only induced intracellular reactive oxygen species (ROS) accumulation but also caused a loss of mitochondrial membrane potential and reduced intracellular ATP generation. In addition, TBTO exposure impaired porcine oocyte quality by disrupting cellular iron homeostasis. Taken together, these results demonstrate that TBTO exposure impairs the porcine oocyte maturation process by inducing intracellular ROS accumulation, causing mitochondrial dysfunction, and disrupting cellular iron homeostasis, thus decreasing the quality and impairing the subsequent embryonic developmental competence of porcine oocytes.

Optimization of the IL-2 Luc assay for immunosuppressive drugs: a novel in vitro immunotoxicity test with high sensitivity and predictivity

We have reported that the IL-2 Luc assay can detect the effects of chemicals on IL-2 promoter activity by using a dual reporter cell line, 2H4 cells that measure IL-2 promoter-driven luciferase activity (IL2LA) and GAPDH promoter-driven luciferase activity (GAPLA). Since the IL-2 Luc assay cannot detect immunosuppressive drugs that are antimitotic towards rapidly proliferating cells, we attempted to establish a new assay to detect these chemicals by taking advantage of the dual reporter cell properties of 2H4 cells. We first determined the optimal incubation time with drugs and the seeding cell density, and confirmed that the change in GAPLA and IL2LA levels reflects the change in cell count and IL-2 production of 2H4 cells after drug treatment. We designed the IL-2 luciferase lymphotoxicity test (IL-2 Luc LTT) to detect the antimitotic effects of chemicals by modifying the protocol and criteria of the IL-2 Luc assay. To determine the performance of the IL-2 Luc LTT and that of the combination of the IL-2 Luc LTT and the IL-2 Luc assay, we examined 46 drugs: 19 immunosuppressive drugs with different mechanisms of action, 12 anti-cancer drugs, and 15 non-immunosuppressive drugs. The performances of the IL-2 Luc LTT, the IL-2 Luc assay and their combination were 43.3%, 61.3%, and 93.3%, respectively, for sensitivity, 84.6%, 53.3%, and 50.0%, respectively, for specificity, and 55.8%, 58.7%, and 79.5%, respectively, for accuracy. These results demonstrated that the combination of these two assays is promising for the detection of immunosuppressive drugs with different mechanisms of action.

MiR-135b Alleviates Airway Inflammation in Asthmatic Children and Experimental Mice with Asthma via Regulating CXCL12

OBJECTIVE

To clarify the possible influence of miR-135b on CXCL12 and airway inflammation in children and experimental mice with asthma.

METHODS

The expressions of miR-135b and CXCL12 were detected using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) in the serum of asthmatic children. Besides, the experimental asthmatic mice were established by aerosol inhalation of ovalbumin (OVA) followed by the treatment with agomiR-135b and antagomir-135b. Pathological changes of lung tissues were observed via HE staining and PAS staining. Besides, the airway hyperresponsiveness of mice was elevated and bronchoalveolar lavage fluid (BALF) was isolated for cell categorization and counting. The inflammatory cytokines in BALF were determined by enzyme-linked immunosorbent assay (ELISA), and the infiltration of Th17 cells in lung tissues was measured using flow cytometry.

RESULTS

MiR-135b was downregulated and CXCL12 was upregulated in asthmatic children and mice. Overexpression of miR-135b may down-regulate CXCL12 expression in the lung of OVA mice, resulting in significant decreases in inflammatory infiltration, hyperplasia of goblet cell, airway hyperresponsiveness, cell quantity, as well as the quantity of eosinophilic granulocytes, neutrophils and lymphocytes in BALF. Also, the levels of inflammatory cytokines (IL-4, IL-5, IL-13 and IL-17) and the ratio of Th17 cells and IL-17 levels in lung tissues were decreased. However, miR-135b downregulation reversed these changes in OVA mice.

CONCLUSION

MiR-135b may inhibit immune responses of Th17 cells to alleviate airway inflammation and hyperresponsiveness in asthma possibly by targeting CXCL12, showing the potential value in asthma treatment.

Emerging role of mTOR in tumor immune contexture: Impact on chemokine-related immune cells migration

During the last few decades, cell-based anti-tumor immunotherapy emerged and it has provided us with a large amount of knowledge. Upon chemokines recognition, immune cells undergo rapid trafficking and activation in disease milieu, with immune cells chemotaxis being accompanied by activation of diverse intercellular signal transduction pathways. The outcome of chemokines-mediated immune cells chemotaxis interacts with the cue of mammalian target of rapamycin (mTOR) in the tumor microenvironment (TME). Indeed, the mTOR cascade in immune cells involves migration and infiltration. In this review, we summarize the available mTOR-related chemokines, as well as the characterized upstream regulators and downstream targets in immune cells chemotaxis and assign potential underlying mechanisms in each evaluated chemokine. Specifically, we focus on the involvement of mTOR in chemokine-mediated immune related cells in the balance between tumor immunity and malignancy.

RIPK1 inhibitor ameliorates colitis by directly maintaining intestinal barrier homeostasis and regulating following IECs-immuno crosstalk

BACKGROUND

The receptor-interacting protein kinase 1 (RIPK1) has emerged as a key upstream regulator that controls the inflammatory response via its kinase-dependent and independent functions, which makes it an attractive target for developing new drugs against inflammation-related diseases. Growing evidences illustrate that RIPK1 is certainly associated with pathogenesis of multiple tissue-damage diseases. However, what are intricate regulatory codes of RIPK1 inhibitor in diseases is still obscure.

METHODS

We used DSS-induced colitis model in vivo to study the therapeutic effects and the mechanisms of RIPK1 inhibitor. We next characterized the barrier function and the interaction between intestinal epithelial cells (IECs) and immunocytes both in vivo and in vitro. As a candidate in clinical study, GSK2982772 is the most well-developed drug of RIPK1 inhibitors, and we chose it as our study object.

RESULTS

We demonstrated that RIPK1 inhibitor could ameliorate the intestinal barrier injury by reducing tight junctions' disruption and accompanying oxidative stress. Moreover, the release of chemokines and adhesion molecules from damaged IECs was suppressed by RIPK1 inhibitor treatment. And these protective effects were not only dependent on the suppression of necroptosis but also on the compromised activity of NF-κB. Taken together, RIPK1 inhibitor exerts suppressive function in intestinal inflammatory response possibly via protecting the intestinal epithelial barrier and maintaining the homeostasis of immune microenvironments. Eventually, the positive feedback immune response which triggered progressive epithelial cells injury could be restrained.

Chemotactic effect of β-defensin 1 on macrophages in Megalobrama amblycephala

Besides their function as a physical barrier against pathogens, β-defensins possess the ability to induce direct or indirect chemotaxis in leukocytes of mammals. However little is known about the ability of defensins to guide the migration of macrophages in fish. The objective of our study was to investigate whether β-defensin 1 (maBD1) can recruit leukocytes (specifically macrophages) in vivo and in vitro in a farmed cyprinid fish Megalobrama amblycephala. The M. amblycephala β-defensin 1 (maBD1) gene was amplified from the head-kidney transcriptome. Synthetic maBD1 polypeptide (as well as its N-terminus half, but not the C-terminus half) was capable of inducing the migration of leukocytes (specifically macrophages) at concentrations from 26.0 μg/mL to 52.0 μg/mL in head kidney tissue in vitro. When injected intraperitoneally in vivo, the number of leukocytes in the peritoneal cavity was in positive correlation with the maBD1 concentration. maBD1 also induced the expression of two proinflammatory cytokines (IL-1beta and TNF-alpha) in spleen, head and body kidney, and hepatopancreas. These results strongly indicate that BD1 has a chemoattractant capacity for macrophages, as well as the ability to modulate the expression of proinflammatory cytokines in fish.