Environment-responsive dopamine nanoplatform for tumor synergistic therapy.

Nanoparticle-based photothermal therapy (PTT) has emerged as a promising approach in tumor treatment due to its high selectivity and low invasiveness. However, the penetration of near-infrared light (NIR) is limited, leading it fails to induce damage to the deep-seated tumor cells within the tumor tissue. Additionally, inefficient uptake of photothermal nanoparticles by tumor cells results in suboptimal outcomes for PTT. In this study, we utilized the adhesive properties of photothermal material, polydopamine (PDA), which can successfully load the photosensitizer indocyanine green (ICG) and chemotherapeutic drug doxorubicin (DOX) to achieve photothermal and chemotherapy synergy treatment (PDA/DOX&ICG), aiming to compensate the defects of single tumor treatment. To extending the blood circulation time of PDA/DOX&ICG nanoparticles, evading clearance by the body immune system and achieving targeted delivery to tumor tissues, a protective envelopment was created using erythrocyte membranes modified with folate acid (FA-EM). After reaching the tumor tissue, the obtained FA-EM@PDA/DOX&ICG nanoparticles can specific bind with folate acid receptors on the surface of tumor cells, which can improve the uptake behavior of FA-EM@PDA/DOX&ICG nanoparticles by tumor cells, and leading to the release of loaded DOX and ICG in response to the unique tumor microenvironment. ICG, as a typical photosensitizer, significantly enhances the photothermal conversion performance of FA-EM@PDA/DOX&ICG nanoparticles, thus inducing tumor cells damage. In vitro and in vivo experimental results demonstrated that the coordinated NIR treatment with FA-EM@PDA/DOX&ICG not only effectively inhibits tumor growth, but also exhibits superior biocompatibility, effectively mitigating DOX-induced tissue damage.

IgG immune complex-induced acute lung injury is ameliorated by cAMP via down-regulation of C/EBP- and AP-1-mediated transcriptions.

BACKGROUND: Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS) are life threatening pulmonary diseases, and we are now lack of effective therapeutic methods. Inflammatory responses are essential for initiating ALI/ARDS. Thus, ameliorating inflammatory reaction might be beneficial for treatment of the disease. There are increasing data that phosphodiesterase-4 (PDE4)-selective inhibitors, which may elevate cellular cyclic adenosine 3', 5'-monophosphate (cAMP) level, could suppress inflammation. However, whether they could be used to treat IgG immune complex (IgG-IC)-associated ALI has not been determined. METHODS: ALI is induced by treating mice with airway deposition of IgG immune complexes. Cellular cAMP concentrations are elevated by treating mice or macrophages with Rolipram/Roflumilast. The degree of pulmonary injury is reflected by lung permeability, leukocyte accumulation, histological change and expressions of pro-inflammatory mediators. 6-Bnz-cAMP and H-89 are used to regulate protein kinase A (PKA) activity, and 8-pCPT-2'-O-Me-cAMP is applied to activate exchange proteins directly activated by cAMP (Epac). Gene expressions are analyzed by real-time PCR, ELISA or Western blot. CCAAT/enhancer binding protein (C/EBP) and activation protein 1 (AP-1) transcription activities are estimated by measuring the luciferase productions. RESULTS: IgG-IC-induced ALI is attenuated by the PDE4-selective inhibitor, which is due to reduced expressions of cytokine and chemokines. Interestingly, we find that cAMP downstream effector molecule PKA but not Epac is involved in negative regulation of IgG-IC-mediated pro-inflammatory mediators' productions. Mechanistically, activation of cAMP-PKA signal axis leads to inactivation of MAPK pathway, resulting in a decrease in C/EBP- and AP-1-mediated transcriptions of pro-inflammatory mediators. CONCLUSIONS: Our data demonstrate, for the first time, that cAMP-PKA signal is involved in down-regulation of IgG-IC-associated inflammatory responses via down-regulating MAPK activation, which is critical for transcriptional activities of C/EBP and AP-1. Collectively, our experiments provide theoretical base for the potential application of PDE4-selective inhibitor to clinic for treatment of IgG-IC-related acute lung injury.

The Crucial Role of PPARγ-Egr-1-Pro-Inflammatory Mediators Axis in IgG Immune Complex-Induced Acute Lung Injury.

Background: The ligand-activated transcription factor peroxisome proliferator-activated receptor (PPAR) γ plays crucial roles in diverse biological processes including cellular metabolism, differentiation, development, and immune response. However, during IgG immune complex (IgG-IC)-induced acute lung inflammation, its expression and function in the pulmonary tissue remains unknown. Objectives: The study is designed to determine the effect of PPARγ on IgG-IC-triggered acute lung inflammation, and the underlying mechanisms, which might provide theoretical basis for therapy of acute lung inflammation. Setting: Department of Pathogenic Biology and Immunology, Medical School of Southeast University. Subjects: Mice with down-regulated/up-regulated PPARγ activity or down-regulation of Early growth response protein 1 (Egr-1) expression, and the corresponding controls. Interventions: Acute lung inflammation is induced in the mice by airway deposition of IgG-IC. Activation of PPARγ is achieved by using its agonist Rosiglitazone or adenoviral vectors that could mediate overexpression of PPARγ. PPARγ activity is suppressed by application of its antagonist GW9662 or shRNA. Egr-1 expression is down-regulated by using the gene specific shRNA. Measures and Main Results: We find that during IgG-IC-induced acute lung inflammation, PPARγ expression at both RNA and protein levels is repressed, which is consistent with the results obtained from macrophages treated with IgG-IC. Furthermore, both in vivo and in vitro data show that PPARγ activation reduces IgG-IC-mediated pro-inflammatory mediators' production, thereby alleviating lung injury. In terms of mechanism, we observe that the generation of Egr-1 elicited by IgG-IC is inhibited by PPARγ. As an important transcription factor, Egr-1 transcription is substantially increased by IgG-IC in both in vivo and in vitro studies, leading to augmented protein expression, thus amplifying IgG-IC-triggered expressions of inflammatory factors via association with their promoters. Conclusion: During IgG-IC-stimulated acute lung inflammation, PPARγ activation can relieve the inflammatory response by suppressing the expression of its downstream target Egr-1 that directly binds to the promoter regions of several inflammation-associated genes. Therefore, regulation of PPARγ-Egr-1-pro-inflammatory mediators axis by PPARγ agonist Rosiglitazone may represent a novel strategy for blockade of acute lung injury.

TNF-α induction of IL-6 in alveolar type II epithelial cells: Contributions of JNK/c-Jun/AP-1 element, C/EBPδ/C/EBP binding site and IKK/NF-κB p65/κB site.

Although participation of IL-6 in lung inflammation has been widely elucidated, the transcriptional regulation of its generation in alveolar type II cells stimulated by TNF-α remain unclear. Here, we find that TNF-α significantly induces IL-6 production, and TNF-α induction of IL-6 is mainly regulated at transcriptional level. Upon stimulated by TNF-α, Activator Protein-1 (AP-1)-mediated transcriptional activity is apparently increased in alveolar type II epithelial cells, which might be derived from elevated phosphorylation of JNK and subsequent activation of c-Jun. Either down-regulation of c-Jun or the AP-1 site mutation leads to significant reduction of IL-6 expression. In contrast, ectopic expression of c-Jun notably increases IL-6 generation. So, c-Jun, one of the AP-1 family members, plays a pivotal role in TNF-α-induced IL-6 generation. CCAAT/enhancer binding protein δ (C/EBPδ) expression is significantly amplified by TNF-α, which may contribute to the rise of C/EBP activity in alveolar type II cells. C/EBPδ shRNA treatment results in attenuation of IL-6 expression in the cells, which is consistent with data by introduction of mutations into the C/EBP site in the promoter. However, overexpression of C/EBPδ greatly increases the IL-6 promoter activity. In addition, data regarding another transactivator in the family-C/EBPß show that it does not affect IL-6 production. We also find that the IKK/NF-κB p65 pathway is activated in TNF-α-treated alveolar type II epithelial cells, and plays an essential role in positive regulation of IL-6 expression in TNF-α-treated alveolar type II epithelial cells via knockdown or forced expression of NF-κB p65, or elimination of κB sites in the IL-6 promoter. Notably, IL-6 promoter-driven luciferase production in primary alveolar type II epithelial cells can also be increased by the ectopic expression of c-Jun, C/EBPδ, and NF-κB p65, respectively. Collectively, our data provide insights into molecular mechanism involved in IL-6 expression in alveolar type II epithelial cells on TNF-α treatment, which provides a theoretical basis for specific inhibition of IL-6 production at the transcriptional level.

Studies of in situ-forming hydrogels by blending PLA-PEG-PLA copolymer with silk fibroin solution.

Hydrogels had been prepared by blending PLA-PEG-PLA copolymer with Bombyx mori silk fibroin (SF) solution. Copolymers were synthesized by ring opening polymerization of L-lactide in the presence of dihydroxyl PEG with molar mass of 400 and 1000, and characterized by using (1)H NMR and DSC. Hydrogels formed leaf-like lamellar structures with many nanoglobules which may reserve drugs or growth factors more effectively. Rheological measurements indicated that the adding of copolymer significantly accelerated the hydrogelation of silk fibroin solution which leads to orders-of-magnitude increase in the complex shear modulus to form rigid hydrogel. Hydrogelation kinetics could be controlled easily by changing the concentration ratio, kinds of copolymer and hydrogelation temperature, suggesting the hydrogels could be formed in situ under physiological conditions with suitable mechanical properties. Furthermore, Fourier transform infrared, X-ray diffraction, and differential thermal analysis were employed to study the structure of hydrogels. The copolymer and SF in blend hydrogels were phase separation. There was an increase of ß-sheet content and formation of silk II structure during hydrogelation. These results may indicate that copolymer/SF hydrogels could be a valuable candidate scaffold as in situ-forming hydrogels for drug/growth factor release in tissue engineering.