Honokiol Ameliorates DSS-Induced Mouse Colitis by Inhibiting Inflammation and Oxidative Stress and Improving the Intestinal Barrier

Targeting Inflammatory Lesions Facilitated by Galactosylation Modified Delivery System Eudragit/Gal-PLGA@Honokiol for the treatment of Ulcerative Colitis

Honokiol (HNK) is one of the bioactive ingredients from the well-known Chinese herbal medicine Magnolia officinalis, and its research interests is rising for its extensive pharmacological activities, including novel therapeutic effect on ulcerative colitis (UC). However, further application of HNK is largely limited by its unique physicochemical properties, such as poor water solubility, low bioavailability, as well as unsatisfied targeting efficacy for inflammatory lesions. In this study, we constructed galactosylation modified PLGA nanoparticles delivery system for efficient target delivery of HNK to the colitic lesions, which could lay a research foundation for the deep development of HNK for the treatment of UC. D-galactose was grafted by chemical coupling reactions with PLGA to prepare Gal-PLGA, which was used as a carrier for HNK (Gal-PLGA@HNK nanoparticles (NPs)). To improve the colon targeting efficiency by oral administration of the NPs, Eudragit S100 was used for wrapping on the surface of Gal-PLGA@HNK NPs (E/Gal-PLGA@HNK NPs). Our results showed that the encapsulation efficiency and drug loading capacity of E/Gal-PLGA@HNK NPs were 90.72 ± 0.54% and 8.41 ± 0.02%, respectively. Its average particle size was 242.24 ± 8.42 nm, with a PDI value of 0.135 ± 0.06 and zeta-potential of -16.83 ± 1.89 mV. The release rate of HNK from E/Gal-PLGA@HNK NPs was significantly decreased when compared with that of free HNK in simulated gastric and intestinal fluids, which displayed a slow-releasing property. It was also found that the cellular uptake of E/Gal-PLGA@HNK NPs was significantly increased when compared with that of free HNK in RAW264.7 cells, which was facilitated by D-galactose grafting on the PLGA carrier. Additionally, our results showed that E/Gal-PLGA@HNK NPs significantly improved colonic atrophy, body weight loss, as well as reducing disease activity index (DAI) score and pro-inflammatory cytokine levels in UC mice induced by DSS. Besides, the retention time of E/Gal-PLGA@HNK NPs in the colon was significantly increased when compared with that of other preparations, suggesting that these NPs could prolong the interaction between HNK and the injured colon. Taken together, the efficiency for target delivery of HNK to the inflammatory lesions was significantly improved by galactosylation modification on the PLGA carrier, which provided great benefits for the alleviation of colonic inflammation and injury in mice.

Honokiol alleviates monosodium urate-induced gouty pain by inhibiting voltage-gated proton channels in mice

OBJECTIVE

To investigate whether honokiol (HNK) acted as an analgesic in connection with inhibiting the voltage-gated proton channel (Hv1).

METHODS

The model of gouty arthritis was induced by injecting monosodium urate (MSU) crystals into the hind ankle joint of mice. HNK was given by intragastric administration. Ankle swelling degree and mechanical allodynia were evaluated using ankle joint circumference measurement and von Frey filaments, respectively. Hv1 current, tail current, and action potential in dorsal root ganglion (DRG) neurons were recorded with patch-clamp techniques.

RESULTS

HNK (10, 20, 40 mg/kg) alleviated inflammatory response and mechanical allodynia in a dose-dependent manner. In normal DRG neurons, 50 µM Zn2+ or 2-GBI significantly inhibited the Hv1 current and the current density of Hv1 increased with increasing pH gradient. The amplitude of Hv1 current significantly increased on the 3rd after MSU treatment, and HNK dose-dependently reversed the upregulation of Hv1 current. Compared with MSU group, 40 mg/kg HNK shifted the activation curve to the direction of more positive voltage and increased reversal potential to the normal level. In addition, 40 mg/kg HNK reversed the down-regulation of tail current deactivation time constant (τtail) but did not alter the neuronal excitability of DRG neurons in gouty mice.

CONCLUSION

HNK may be a potential analgesic by inhibiting Hv1 current.

Protective effect of FKBP12 on dextran sulfate sodium-induced ulcerative colitis in mice as a tacrolimus receptor

Ulcerative colitis (UC) is a multifactorial intestinal disease with a high incidence. In recent years, there has been an urgent need for pleiotropic drugs with a clear biosafety profile. Tacrolimus (TAC) is an immunosuppressant with stronger in vivo effects and better gastrointestinal absorption and is considered a potential treatment for UC. FKBP12 is a mediator of TAC immunosuppression; however, it is unclear whether it can participate in the development of UC in combination with TAC. The purpose of this study is to preliminarily validate the function of FKBP12 by establishing dextran sulfate sodium (DSS)-induced UC model and TAC treatment. The results revealed that TAC was effective in alleviating DSS-induced UC symptoms such as body weight and disease activity index (DAI). TAC significantly protects colonic tissue and attenuates DSS-induced histomorphological changes. In addition, FKBP12 is down-regulated in the intestinal tissue of DSS-induced UC mice and in serum samples of UC patients. In conclusion, our study revealed that FKBP12 may act as a TAC receptor to have anti-inflammatory and protective effects on DSS-induced UC in mice, which will provide a new option for the treatment of UC.

Isofraxidin attenuates dextran sulfate sodium-induced ulcerative colitis through inhibiting pyroptosis by upregulating Nrf2 and reducing reactive oxidative species

BACKGROUND

Ulcerative colitis (UC), a non-specific gastrointestinal disease, is commonly managed with aminosalicylic acids and immunosuppressive agents to control inflammation and relieve symptoms, despite frequent relapses. Isofraxidin is a coumarin compound extracted from traditional Chinese medicine, exhibiting anti-inflammatory and antioxidant properties; however, its alleviating effect on UC remains unclear. Therefore, we investigated the mechanism of isofraxidin in lipopolysaccharide (LPS)-induced cell inflammation in human intestinal epithelial cell (HIEC) and human colorectal adenocarcinoma cells (Caco-2), as well as in dextran sulfate sodium (DSS)-induced UC in mice.

METHODS

We established colitis models in HIEC and Caco-2 cells and mice with LPS and DSS, respectively. Additionally, NLRP3 knockout mice and HIEC cells transfected with NLRP3 silencing gene and ML385 illustrated the role of isofraxidin in pyroptosis and oxidative stress. Data from cells and mice analyses were subjected to one-way analysis of variance or a paired t-test.

RESULTS

Isofraxidin significantly alleviated LPS-induced cell inflammation and reduced lactic dehydrogenase release. Isofraxidin also reversed DSS- or LPS-induced pyroptosis in vivo and in vitro, increasing the expression of pyroptosis-related proteins. Moreover, isofraxidin alleviated oxidative stress induced by DSS or LPS, reducing reactive oxidative species (ROS), upregulation nuclear factor erythroid 2-related factor 2 (Nrf2), and promoting its entry into the nucleus. Mechanistically, ML385 reversed the inhibitory effect of isofraxidin on ROS and increased pyroptosis.

CONCLUSION

Isofraxidin can inhibit pyroptosis through upregulating Nrf2, promoting its entry into the nucleus, and reducing ROS, thereby alleviating DSS-induced UC. Our results suggest isofraxidin as a promising therapeutic strategy for UC treatment.

Endoplasmic reticulum stress related genome-wide Mendelian randomization identifies therapeutic genes for ulcerative colitis and Crohn's disease

Background: Endoplasmic reticulum stress (ERS) is an important pathophysiological mechanism in ulcerative colitis (UC) and Crohn's disease (CD). ERS-related genes may be influenced by genetic factors and intestinal inflammation. However, the role of ERS as a trigger or potential etiological factor for UC and CD is unclear, as the expression of ERS-related genes in UC and CD may be the cause or subsequent changes in intestinal inflammation. Here, we used a three-step summary data-based Mendelian randomization (SMR) approach integrating multi-omics data to identify putative causal effects of ERS-related genes in UC and CD. Methods: Genome-wide association study (GWAS) summary data for UC (6,968 cases and 20,464 controls) and CD (5,956 cases and 14,927 controls) were extracted as outcome, and DNA methylation quantitative trait loci (mQTL, 1,980 participants) data and expression QTL data (eQTL, 31,684 participants) from the blood were obtained as exposure. The ERS-related genes were extracted from the GeneCards database, and then the GWAS summary data were integrated with the mQTL and eQTL data associated with ERS genes by SMR. Sensitivity analysis included two-sample MR analysis, power calculations, Bayesian co-localization analysis, and phenotype scanning were performed to evaluate the robustness of the results. Results: A total of 1,193 ERS-related genes were obtained. The three-step SMR analysis showed that cg24011261 CpG site regulating GPX1 expression was associated with a low risk of UC, whereas GPX1 expression regulated by a combination of cg05055782, cg24011261, and cg05551922 CpG sites was associated with a low risk of CD. Sensitivity analysis further supports these findings. Conclusion: This multi-omics integration study identifies a causal relationship between the role of ERS in UC and CD and suggests potential new therapeutic targets for clinical practice.

The role of Nrf2 in the pathogenesis and treatment of ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease involving mainly the colorectal mucosa and submucosa, the incidence of which has been on the rise in recent years. Nuclear factor erythroid 2-related factor 2 (Nrf2), known for its key function as a transcription factor, is pivotal in inducing antioxidant stress and regulating inflammatory responses. Numerous investigations have demonstrated the involvement of the Nrf2 pathway in maintaining the development and normal function of the intestine, the development of UC, and UC-related intestinal fibrosis and carcinogenesis; meanwhile, therapeutic agents targeting the Nrf2 pathway have been widely investigated. This paper reviews the research progress of the Nrf2 signaling pathway in UC.