Injectable Oxygen-Carrying Microsphere Hydrogel for Dynamic Regulation of Redox Microenvironment of Wounds.

The delayed healing of infected wounds can be attributed to the increased production of reactive oxygen species (ROS) and consequent damages to vascellum and tissue, resulting in a hypoxic wound environment that further exacerbates inflammation. Current clinical treatments including hyperbaric oxygen therapy and antibiotic treatment fail to provide sustained oxygenation and drug-free resistance to infection. To propose a dynamic oxygen regulation strategy, this study develops a composite hydrogel with ROS-scavenging system and oxygen-releasing microspheres in the wound dressing. The hydrogel itself reduces cellular damage by removing ROS derived from immune cells. Simultaneously, the sustained release of oxygen from microspheres improves cell survival and migration in hypoxic environments, promoting angiogenesis and collagen regeneration. The combination of ROS scavenging and oxygenation enables the wound dressing to achieve drug-free anti-infection through activating immune modulation, inhibiting the secretion of pro-inflammatory cytokines interleukin-6, and promoting tissue regeneration in both acute and infected wounds of rat skins. Thus, the composite hydrogel dressing proposed in this work shows great potential for dynamic redox regulation of infected wounds and accelerates wound healing without drugs.

A Gas Therapy Strategy for Intestinal Flora Regulation and Colitis Treatment by Nanogel-Based Multistage NO Delivery Microcapsules.

Current approaches to treating inflammatory bowel disease focus on the suppression of overactive immune responses, the removal of reactive intestinal oxygen species, and regulation of the intestinal flora. However, owing to the complex structure of the gastrointestinal tract and the influence of mucus, current small-molecule and biologic-based drugs for treating colitis cannot effectively act at the site of colon inflammation, and as a result, they tend to exhibit low efficacies and toxic side effects. In this study, nanogel-based multistage NO delivery microcapsules are developed to achieve NO release at the inflammation site by targeting the inflammatory tissues using the nanogel. Surprisingly, oral administration of the microcapsules suppresses the growth of pathogenic bacteria and increases the abundance of probiotic bacteria. Metabolomics further show that an increased abundance of intestinal probiotics promotes the production of metabolites, including short-chain fatty acids and indole derivatives, which modulate the intestinal immunity and restore the intestinal barrier via the interleukin-17 and PI3K-Akt signaling pathways. This work reveals that the developed gas therapy strategy based on multistage NO delivery microcapsules modulates the intestinal microbial balance, thereby reducing inflammation and promoting intestinal barrier repair, ultimately providing a new therapeutic approach for the clinical management of colitis.

All-Natural Immunomodulatory Bioadhesive Hydrogel Promotes Angiogenesis and Diabetic Wound Healing by Regulating Macrophage Heterogeneity.

Macrophages are highly heterogeneous and exhibit a diversity of functions and phenotypes. They can be divided into pro-inflammatory macrophages (M1) and anti-inflammatory macrophages (M2). Diabetic wounds are characterized by a prolonged inflammatory phase and difficulty in healing due to the accumulation of pro-inflammatory (M1) macrophages in the wound. Therefore, hydrogel dressings with macrophage heterogeneity regulation function hold great promise in promoting diabetic wound healing in clinical applications. However, the precise conversion of pro-inflammatory M1 to anti-inflammatory M2 macrophages by simple and biosafe approaches is still a great challenge. Here, an all-natural hydrogel with the ability to regulate macrophage heterogeneity is developed to promote angiogenesis and diabetic wound healing. The protocatechuic aldehyde hybridized collagen-based all-natural hydrogel exhibits good bioadhesive and antibacterial properties as well as reactive oxygen species scavenging ability. More importantly, the hydrogel is able to convert M1 macrophages into M2 macrophages without the need for any additional ingredients or external intervention. This simple and safe immunomodulatory approach shows great application potential for shortening the inflammatory phase of diabetic wound repair and accelerating wound healing.

Baicalin prevents LPS-induced activation of TLR4/NF-κB p65 pathway and inflammation in mice via inhibiting the expression of CD14.

Previous studies have shown that baicalin, an active ingredient of the Chinese traditional medicine Huangqin, attenuates LPS-induced inflammation by inhibiting the activation of TLR4/NF-κBp65 pathway, but how it affects this pathway is unknown. It has been shown that CD14 binds directly to LPS and plays an important role in sensitizing the cells to minute quantities of LPS via chaperoning LPS molecules to the TLR4/MD-2 signaling complex. In the present study we investigated the role of CD14 in the anti-inflammatory effects of baicalin in vitro and in vivo. Exposure to LPS (1 µg/mL) induced inflammatory responses in RAW264.7 cells, evidenced by marked increases in the expression of MHC II molecules and the secretion of NO and IL-6, and by activation of MyD88/NF-κB p65 signaling pathway, as well as the expression of CD14 and TLR4. These changes were dose-dependently attenuated by pretreatment baicalin (12.5-50 µM), but not by baicalin post-treatment. In RAW264.7 cells without LPS stimulation, baicalin dose-dependently inhibit the protein and mRNA expression of CD14, but not TLR4. In RAW264.7 cells with CD14 knockdown, baicalin pretreatment did not prevent inflammatory responses and activation of MyD88/NF-κB p65 pathway induced by high concentrations (1000 µg/mL) of LPS. Furthermore, baicalin pretreatment also inhibited the expression of CD14 and activation of MyD88/NF-κB p65 pathway in LPS-induced hepatocyte-derived HepG2 cells and intestinal epithelial-derived HT-29 cells. In mice with intraperitoneal injection of LPS and in DSS-induced UC mice, oral administration of baicalin exerted protective effects by inhibition of CD14 expression and inflammation. Taken together, we demonstrate that baicalin pretreatment prevents LPS-induced inflammation in RAW264.7 cells in CD14-dependent manner. This study supports the therapeutic use of baicalin in preventing the progression of LPS-induced inflammatory diseases.

Oroxindin inhibits macrophage NLRP3 inflammasome activation in DSS-induced ulcerative colitis in mice via suppressing TXNIP-dependent NF-κB pathway.

Oroxindin is a flavonoid isolated from the traditional Chinese medicine Huang-Qin, which has shown various pharmacological activities including anti-inflammatory, antitumor, antioxidant, etc. Thus far, the effect of oroxindin on colonic inflammation and the underlying mechanism remain unknown. In this study, we investigated the tissue distribution of oroxindin and its therapeutic effects on ulcerative colitis (UC) as well as the underlying mechanisms. UC model was established in mice by administrating dextran sulfate sodium (DSS) in drinking water for 7 d. We first showed that oroxindin was largely absorbed by the colon as an active ingredient after normal mice received Huang-Qin-Tang, a traditional Chinese medicine decoction. UC mice were then treated with oroxindin (12.5, 25, 50 mg ·kg-1 ·d-1, i.g.) for 10 d. We found that oroxindin treatment greatly suppressed massive macrophages infiltration and attenuated pathological changes in colonic tissue. Furthermore, oroxindin treatment significantly inhibited the generation of IL-1ß and IL-18 in the colon via inhibiting the nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome formation and activation. In cultured macrophages, LPS induced NLRP3 inflammasome formation and caspase-1 activation, which were suppressed by oroxindin (12.5-50 µM). In LPS-treated macrophages, oroxindin dose-dependently restored the expression of TXNIP protein, leading to suppressing TXNIP-dependent NF-κB activation. In conclusion, these results demonstrate that oroxindin could be absorbed by the colon and attenuate inflammatory responses via inhibiting NLRP3 inflammasome formation and activation, which is related to the inhibitory effect on TXNIP-dependent NF-κB-signaling pathway. Hence, oroxindin has the potential of becoming an effective drug for treating UC.

A near-infrared fluorescent probe based on BODIPY derivative with high quantum yield for selective detection of exogenous and endogenous cysteine in biological samples.

Cysteine (Cys) is involved in cellular growth and Cys deficiency is related with many diseases. So far, a number of fluorescent probes have been constructed for the detection of Cys successfully. However, the probes are difficult to discriminate Cys from Hcy and the emission wavelength of the probes is in ultraviolet or visible range. Herein, a NIR fluorescent probe named NIR-BODIPY-Ac is synthesized and used to detect Cys. The emission wavelength of the probe is at 708 nm that belongs to near-infrared (NIR) region by attaching indolium to BODIPY core, which is suitable for bioimaging in vivo. Moreover, the probe exhibits high fluorescence quantum yield (Φ = 0.51) after the addition of Cys and high sensitivity toward Cys with 81-fold fluorescence enhancement. The linear range of the probe for Cys covers from 0.2 to 30 µM with a detection limit of 0.05 µM. Furthermore, the probe shows high selectivity towards Cys owing to the fact that there is more fast reaction rate between the probe and Cys than that of Hcy. In particular, the NIR fluorescent probe is applied for the detection of exogenous and endogenous Cys in biological samples such as cell, tissue and mouse with satisfactory results.

Real-Time Monitoring ATP in Mitochondrion of Living Cells: A Specific Fluorescent Probe for ATP by Dual Recognition Sites.

Adenosine triphosphate (ATP) is mainly produced in the mitochondrion and used as a universal energy source for various cellular events. Various fluorescent probes for ATP have been established successfully, but most of them are not appropriate for monitoring the fluctuation of the mitochondrial ATP level. Herein, a fluorescent probe named Mito-Rh is first synthesized and used to recognize ATP in mitochondrion. In the probe, rhodamine, diethylenetriamine, and triphenylphosphonium are selected as fluorophore, reaction site, and mitochondrion-targeting group, respectively. Probe Mito-Rh shows high sensitivity to ATP with 81-fold fluorescence enhancement, and the detection range (0.1-10 mM) can match the concentration level of ATP in the mitochondrion. Moreover, Mito-Rh provides excellent selectivity toward ATP over other biological anions (ADP, AMP, GTP, CTP, UTP) owing to a concurrent effect of dual recognition sites (hydrogen bond and π-π stacking). In particular, the probe can localize in mitochondrion specifically and demonstrates utility in the real-time detection of mitochondrial ATP concentration changes.