Luteolin attenuates endotoxin-induced uveitis in Lewis rats

Autoimmune uveitis attenuated in diabetic mice through imbalance of Th1/Th17 differentiation via suppression of AP-1 signaling pathway in Th cells

Purpose

Inflammation is involved in the pathogenesis of diabetes, however the impact of diabetes on organ-specific autoimmune diseases remains unexplored. Experimental autoimmune uveoretinitis (EAU) is a widely accepted animal model of human endogenous uveitis. In this study, we investigated the effects of diabetic conditions on the development of EAU using a mouse diabetes model.

Methods

EAU was induced in wild-type C57BL/6 (WT) mice and Ins2Akita (Akita) mice with spontaneous diabetes by immunization with IRBP peptide. Clinical and histopathological examinations, and analysis of T cell activation state were conducted. In addition, alternations in the composition of immune cell types and gene expression profiles of relevant immune functions were identified using single-cell RNA sequencing.

Results

The development of EAU was significantly attenuated in immunized Akita (Akita-EAU) mice compared with immunized WT (WT-EAU) mice, although T cells were fully activated in Akita-EAU mice, and the differentiation into Th17 cells and regulatory T (Treg) cells was promoted. However, Th1 cell differentiation was inhibited in Akita-EAU mice, and single-cell analysis indicated that gene expression associated AP-1 signaling pathway (JUN, FOS, and FOSB) was downregulated not only in Th1 cells but also in Th17, and Treg cells in Akita-EAU mice at the onset of EAU.

Conclusions

In diabetic mice, EAU was significantly attenuated. This was related to selective inhibition of Th1 cell differentiation and downregulated AP-1 signaling pathway in both Th1 and Th17 cells.

Topical Sustained-Release Dexamethasone-Loaded Chitosan Nanoparticles: Assessment of Drug Delivery Efficiency in a Rabbit Model of Endotoxin-Induced Uveitis

Uveitis is an ocular illness that if not treated properly can lead to a total loss of vision. In this study, we evaluated the utility of HA-coated Dexamethasone-sodium-phosphate (DEX)-chitosan nanoparticles (CSNPs) coated with hyaluronic acid (HA) as a sustained ocular delivery vehicle for the treatment of endotoxin-induced-uveitis (EIU) in rabbits. The CSNPs were characterized for particle size, zeta potential, polydispersity, surface morphology, and physicochemical properties. Drug encapsulation, in vitro drug release, and transcorneal permeation were also evaluated. Finally, eye irritation, ocular pharmacokinetics, and pharmacodynamics were in vivo. The CSNPs ranged from 310.4 nm and 379.3 nm pre-(uncoated) and post-lyophilization (with HA-coated), respectively. The zeta potentials were +32 mV (uncoated) and -5 mV (HA-uncoated), while polydispersity was 0.178-0.427. Drug encapsulation and loading in the CSNPs were 73.56% and 6.94% (uncoated) and 71.07% and 5.54% (HA-coated), respectively. The in vitro DEX release over 12 h was 77.1% from the HA-coated and 74.2% from the uncoated NPs. The physicochemical properties of the CSNPs were stable over a 3-month period when stored at 25 °C. Around a 10-fold increased transcorneal-flux and permeability of DEX was found with HA-CSNPs compared to the DEX-aqueous solution (DEX-AqS), and the eye-irritation experiment indicated its ocular safety. After the ocular application of the CSNPs, DEX was detected in the aqueous humor (AH) till 24 h. The area under the concentrations curve (AUC0-24h) for DEX from the CSNPs was 1.87-fold (uncoated) and 2.36-fold (HA-coated) higher than DEX-AqS. The half-life (t1/2) of DEX from the uncoated and HA-coated NPs was 2.49-and 3.36-fold higher, and the ocular MRT0-inf was 2.47- and 3.15-fold greater, than that of DEX-AqS, respectively. The EIU rabbit model showed increased levels of MPO, TNF-α, and IL-6 in AH. Topical DEX-loaded CSNPs reduced MPO, TNF-α, and IL-6 levels as well as inhibited NF-κB expression. Our findings demonstrate that the DEX-CSNPs platform has improved the delivery properties and, hence, the promising anti-inflammatory effects on EIU in rabbits.

Luteolin ameliorates cornea stromal collagen degradation and inflammatory damage in rats with corneal alkali burn

Corneal alkali burn (AB) is a blindness-causing ocular trauma commonly seen in clinics. An excessive inflammatory reaction and stromal collagen degradation contribute to corneal pathological damage. Luteolin (LUT) has been studied for its anti-inflammatory effects. In this study, the effect of LUT on cornea stromal collagen degradation and inflammatory damage in rats with corneal alkali burn was investigated. After corneal alkali burn, rats were randomly assigned to the AB group and AB + LUT group and received an injection of saline and LUT (200 mg/kg) once daily. Subsequently, corneal opacity, epithelial defects, inflammation and neovascularization (NV) were observed and recorded on Days 1, 2, 3, 7 and 14 post-injury. The concentration of LUT in ocular surface tissues and anterior chamber, as well as the levels of collagen degradation, inflammatory cytokines, matrix metalloproteinases (MMPs) and their activity in the cornea were detected. Human corneal fibroblasts (HCFs) were co-cultured with interleukin (IL)-1β and LUT. Cell proliferation and apoptosis were assessed by CCK-8 assay and flow cytometry respectively. Measurement of hydroxyproline (HYP) in culture supernatants was used to quantify the amount of collagen degradation. Plasmin activity was also assessed. ELISA or real-time PCR was used to detect the production of matrix metalloproteinases (MMPs), IL-8, IL-6 and monocyte chemotactic protein (MCP)-1. Furthermore, the immunoblot method was used to assess the phosphorylation of mitogen-activated protein kinases (MAPKs), transforming growth factor-β-activated kinase (TAK)-1, activator protein-1 (AP-1) and inhibitory protein IκB-α. At last, immunofluorescence staining helped to develop nuclear factor (NF)-κB. LUT was detectable in ocular tissues and anterior chamber after intraperitoneal injection. An intraperitoneal injection of LUT ameliorated alkali burn-elicited corneal opacity, corneal epithelial defects, collagen degradation, NV, and the infiltration of inflammatory cells. The mRNA expressions of IL-1β, IL-6, MCP-1, vascular endothelial growth factor (VEGF)-A, MMPs in corneal tissue were downregulated by LUT intervention. And its administration reduced the protein levels of IL-1β, collagenases, and MMP activity. Furthermore, in vitro study showed that LUT inhibited IL-1β-induced type I collagen degradation and the release of inflammatory cytokines and chemokines by corneal stromal fibroblasts. LUT also inhibited the IL-1β-induced activation of TAK-1, mitogen-activated protein kinase (MAPK), c-Jun, and NF-κB signaling pathways in these cells. Our results demonstrate that LUT inhibited alkali burn-stimulated collagen breakdown and corneal inflammation, most likely by attenuating the IL-1β signaling pathway. LUT may therefore prove to be of clinical value for treating corneal alkali burns.

Luteolin Attenuates APEC-Induced Oxidative Stress and Inflammation via Inhibiting the HMGB1/TLR4/NF-κB Signal Axis in the Ileum of Chicks

Avian pathogenic E. coli (APEC) is typically the cause of avian colibacillosis, which can result in oxidative stress, inflammation, and intestinal damage (APEC). Luteolin, in the form of glycosylation flavone, has potent anti-inflammatory and anti-oxidative properties. However, its effects on APEC-induced intestinal oxidative stress and NF-κB-mediated inflammation in chicks remains poorly understood. After hatching, one-day-old chicks were stochastically assigned to four groups: a control group (basic diet), an E. coli group (basic diet) and L10 and L20 groups (with a dry matter of luteolin diet 10 mg/kg and 20 mg/kg, respectively), with fifteen chicks in each group and one repeat per group. They were pretreated for thirteen days. The body weight, mortality, histopathological changes in the ileum, antioxidant status, and the mRNA and protein-expression levels of factors associated with the HMGB1/TLR4/NF-κB signal axis of the chicks were measured. The results showed that luteolin treatment decreased the mRNA and protein-expression level of the related factors of HMGB1/TLR4/NF-κB signal axis in the ileum, reduced inflammation, increased antioxidant enzyme activity, and reduced intestinal injury. Collectively, luteolin alleviated APEC-induced intestinal damage by means of hindering the HMGB1/TLR4/NF-κB signal axis, which suggests that luteolin could be a good method for the prevention and treatment of avian colibacillosis.

Uncovering the pharmacological mechanism of the effects of the Banxia-Xiakucao Chinese Herb Pair on sleep disorder by a systems pharmacology approach

Sleep disorder (SD) has a high incidence and seriously affects quality of life, mental health and even the manifestation of physical diseases. The combination of Pinellia ternata (Chinese name: banxia) and Prunella vulgaris (Chinese name: xiakucao), known as the Banxia-Xiakucao Chinese herb pair (BXHP), is a proven Chinese herbal medicine that has been used to treat SD for thousands of years due to its significant clinical effects. However, its active pharmacological components and sedative-hypnotic mechanisms have not been fully elucidated. Thus, the present study used a systematic pharmacological approach to develop pharmacokinetic screens and target predictions via construction of a protein-protein interaction network and annotation database for SD-related and putative BXHP-related targets. Visualization, screening and integrated discovery enrichment analyses were conducted. The BXHP chemical database contains 166 compounds between the two herbal ingredients, and of these, 22 potential active molecules were screened by pharmacokinetic evaluation. The targets of 114 of the active molecules were predicted, and 34 were selected for further analysis. Finally, gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses suggested that BXHP can reduce inflammatory responses. and mediate immune-related and central nervous system neurotransmitters via regulation of multiple targets and pathways. The use of a systematic pharmacology-based approach in the present study further elucidated the mechanisms of action underlying BXHP for the treatment of SD from a holistic perspective and sheds light on the systemic mechanisms of action of Chinese herbal medicines in general.

Luteolin Suppresses Sepsis-Induced Cold-Inducible RNA-Binding Protein Production and Lung Injury in Neonatal Mice

ABSTRACT

Neonatal sepsis is a life-threatening inflammatory condition. Extracellular cold-inducible RNA-binding protein (CIRP), a proinflammatory mediator, plays a critical role in the pathogenesis of sepsis-induced lung injury in neonates. Luteolin, a polyphenolic flavonoid, has potent anti-inflammatory properties. However, the effects of luteolin on CIRP production and neonatal sepsis-induced lung injury remained unknown. We therefore hypothesize that treatment with luteolin suppresses CIRP production and attenuates lung injury in neonatal sepsis. To study this, sepsis was induced in C57BL/6J mouse pups (5-7 days) by intraperitoneal cecal slurry injection (CSI). One hour after CSI, luteolin (10 mg/kg body weight) or vehicle (normal saline) was administered through intraperitoneal injection. CIRP mRNA and protein were determined and lung injury was assessed at 10 h after CSI. Our results showed that administration of luteolin decreased CIRP mRNA and protein, improved lung architecture, reduced lung edema, and apoptosis after CSI. To examine the direct effect of luteolin on CIRP production, peritoneal macrophages were isolated from neonatal mice and stimulated with 100 ng/mL LPS with or without the presence of luteolin. The result indicates that luteolin directly inhibited LPS-induced CIRP production in neonatal macrophages. In addition, luteolin also downregulated hypoxia-inducible factor-1α (HIF-1α) and NOD-like receptor 3 (NLRP3) expression in septic neonates and in LPS-stimulated neonatal macrophages. In conclusion, administration of luteolin suppresses CIRP production and attenuates lung injury in neonatal sepsis. The beneficial effect of luteolin may be related to downregulation of HIF-1α and NLRP3 expression in neonatal macrophages. Luteolin may be developed as an adjunctive therapy for neonatal sepsis.

Lutein Suppresses Oxidative Stress and Inflammation by Nrf2 Activation in an Osteoporosis Rat Model

Background

Osteoporosis is a major health risk for women worldwide. Osteoporosis is caused by an imbalance between bone resorption and formation. Hormonal imbalance and increased redox signaling cause bone deterioration.

Material/Methods

Oxidative stress was determined through assessment of ROS, lipid peroxide levels, and antioxidant activity. Inflammatory protein markers and Nrf2-related protein expressions were determined through Western blot analysis. Interleukin expressions were determined using ELSA.

Results

In the present study, we showed that supplementation of lutein protects the ovariectomized (OVX) rats against oxidative stress through its antioxidant protection. OVX rats showed an increase in oxidative stress markers. Lutein treatment significantly decreased the lipid peroxidation levels and ROS in the OVX rats. OVX rats showed inflammatory responses through NF-κB activation and increased inflammatory cytokines (TNF-α, IL-6, IL-8). Further, there was significant upregulation in osteoclast-specific marker NFATc1 in OVX rats compared to sham rats. Lutein supplementation activated Nrf2 driven antioxidant gene expression (HO-1, NQO1) and protected OVX rats against inflammatory responses.

Conclusions

We showed the critical role of Lutein in protection against osteoporosis in OVX rats by downregulation of inflammation and osteoclast-specific marker (NFATc1) expression through Nrf2 activation.

Therapeutic anti-inflammatory effects of luteolin on endotoxin-induced uveitis in Lewis rats

The present study aimed to investigate the therapeutic efficacy of post-inflammatory treatment with luteolin on endotoxin-induced uveitis (EIU) in rats. Intraperitoneal injection of 10 mg/kg luteolin or 1 mg/kg prednisolone (Pred) at 4 hr post-lipopolysaccharide (LPS) injection (200 µg) was associated at 24 hr post-LPS injection with decreased clinical severity scores, number of inflammatory cells, protein levels and levels of tumor necrosis factor (TNF)-α, nitric oxide (NO) and prostaglandin (PG) E2 in the aqueous humor (AqH) and degrees of histological ocular tissue injury. The anti-inflammatory potency of luteolin was comparable to that of Pred. Luteolin exhibited robust efficacy in the treatment of EIU in rats, indicating its potential clinical utility in treating uveitis.