Naringin alleviates pneumonia caused by Klebsiella pneumoniae infection by suppressing NLRP3 inflammasome

Klebsiella pneumoniae (Kpn) is an important pathogen of hospital-acquired pneumonia, which can lead to sepsis and death in severe cases. In this study, we simulated pneumonia induced by Kpn infection in mice to investigate the therapeutic effect of naringin (NAR) on bacterial-induced lung inflammation. Mice infected with Kpn exhibited increases in white blood cells (WBC) and neutrophils in the peripheral blood and pathological severe injury of the lungs. This injury was manifested by increased expression of the inflammatory cytokines interleukin (IL)- 18, IL-1β, tumor necrosis factor-α (TNF-α) and IL-6, and elevated the expression of NLRP3 protein. NAR treatment could decrease the protein expression of NLRP3, alleviate lung inflammation, and reduce lung injury in mice caused by Kpn. Meanwhile, molecular docking results suggest NAR could bind to NLRP3 and Surface Plasmon Resonance (SPR) analyses also confirm this result. In vitro trials, we found that pretreated with NAR not only inhibited nuclear translocation of nuclear factor (NF)-κB protein P65 but also attenuated the protein interaction of NLRP3, caspase-1 and ASC and inhibited the assembly of NLRP3 inflammasome in mice AMs. Additionally, NAR could reduce intracellular potassium (K+) efflux, inhibiting NLRP3 inflammasome activation. These results indicated that NAR could protect against Kpn-induced pneumonia by inhibiting the overactivation of the NLRP3 inflammasome signaling pathway. The results of this study confirm the efficacy of NAR in treating bacterial pneumonia, refine the mechanism of action of NAR, and provide a theoretical basis for the research and development of NAR as an anti-inflammatory adjuvant.

Metabolomics of the anti-inflammatory effect of Pueraria lobata and Pueraria lobata var. Thomsonii in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Pueraria lobata (Willd.) Ohwi and Pueraria lobata var. Thomsonii (Benth.) Maesen are essential medicinal and edible homologous plants widely cultivated in Asian countries. Therefore, P. lobata and P. thomsonii are widely used in the food, health products and pharmaceutical industries and have significant domestic and international market potential and research value. P. lobata and P. thomsonii have pharmacological effects in the clinic, such as antipyretic, analgesic, anti-inflammatory and antioxidant effects. These plants are commonly used in the treatment of inflammatory diseases and other related diseases. However, the potential mechanisms of the anti-inflammatory effects of P. lobata and P. thomsonii have not been elucidated.

AIM OF THE STUDY

This study aimed to confirm the anti-inflammatory effects of P. lobata and P. thomsonii on inflammatory model diseases and to investigate the mechanism of their anti-inflammatory effects from the perspective of plasma metabolomics.

MATERIALS AND METHODS

First, P. lobata and P. thomsonii were identified by high‒performance liquid chromatography (HPLC). Second, we established the following three inflammation models: an acute inflammation model of auricular swelling in mice induced by xylene, an acute inflammation model of foot swelling in rats induced by carrageenan gum, and a chronic inflammation model of cotton ball granuloma in rats. Then we examined the weight and swelling rate of auricular swelling in mice; the residence time, contact area, and mean contact pressure in rats on the gait meter; and the weight of granulomas in rats and the content of IL-1β and TNF-α in plasma to investigate the anti-inflammatory pharmacodynamics of P. lobata and P. thomsonii. Third, we used LC‒MS‒based plasma metabolomics techniques to obtain potential biomarkers of P. lobata and P. thomsonii related to inflammation. Then, the potential biomarkers were enriched by MetaboAnalyst and KEGG metabolomics analysis tools to obtain metabolic pathways related to inflammation. Finally, we tested the indicators of COX-2, 5-LOX, GSH, GSSG and γ⁃GCL in rat plasma from the granuloma model by enzyme-linked immunosorbent assays (ELISAs) to verify the inflammation-related metabolic pathway.

RESULTS

The experimental results showed that P. lobata and P. thomsonii could reduce the swollen weight and swelling rate of the auricle in mice, and could increase the residence time, contact area and mean contact pressure in rats on the gait meter. Moreover, P. lobata and P. thomsonii could inhibit the growth of granulomas and reduce the content of IL-1β and TNF-α in plasma in rats. The above results preliminarily verified that P. lobata and P. thomsonii have different anti-inflammatory effects. We identified eighteen plasma biomarkers associated with P. lobata and sixteen plasma biomarkers related to P. thomsonii in regulating inflammation by a plasma metabolomics analysis. The following two major metabolic pathways were further screened and enriched: arachidonic acid metabolism and glutathione metabolism. Then we noted that P. lobata and P. thomsonii could reduce the COX-2, 5-LOX and GSSG levels and increase the GSH, GSH/GSSG and γ⁃GCL levels based on the ELISA results, which demonstrated that P. lobata and P. thomsonii affect the anti-inflammatory mechanism through arachidonic acid metabolism and glutathione metabolism.

CONCLUSIONS

The results of this study further elucidate the anti-inflammatory mechanism of action of P. lobata and P. thomsonii, providing a scientific basis for developing new drugs for the treatment of inflammation-related diseases and laying a foundation for the development of herbal resources, such as P. lobata and P. thomsonii.

The antimicrobial peptide LK2(6)A(L) exhibits anti-inflammatory activity by binding to the myeloid differentiation 2 domain and protects against LPS-induced acute lung injury in mice

Acute lung injury (ALI) is a life-threatening disease that is generally attributable to an uncontrolled inflammatory response in the lung, but there is a lack of effective treatments. At present, regulating the inflammatory response has become an important strategy for treating ALI. In the present study, LK2(6)A(L), a peptide derived from the natural antimicrobial peptide temporin-1CEa, inhibited lipopolysaccharide (LPS)-induced expression of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and NO in RAW264.7 cells. Herein, the anti-inflammatory mechanism of LK2(6)A(L) was investigated. The RNA-sequencing (RNA-seq) results showed that LK2(6)A(L) significantly inhibited the TLR4-mediated NF-κB and MAPK signaling pathways in LPS-induced RAW264.7 cells. The results of co-immunoprecipitation (Co-IP), pull-down experiment, confocal laser scanning microscopy, and surface plasmon resonance (SPR) suggested that MD2 was the direct target of LK2(6)A(L). Chemical inhibition of MD2 and its knockdown abolished the anti-inflammatory effect of LK2(6)A(L). Molecular dynamic simulation indicated that LK2(6)A(L) could bind to the active domain of the MD2 hydrophobic pocket via six hydrogen bonds. The truncated peptides were designed based on analysis of the molecular docking of LK2(6)A(L) to MD2. The truncated peptide IS-7 showed strong affinity to MD2 and a remarkable inhibitory effect on pro-inflammatory factors that was comparable to the effect of LK2(6)A(L). Finally, LK2(6)A(L) and IS-7 relieved inflammatory symptoms and lung tissue destruction in the ALI mouse model. Overall, our study suggested that LK2(6)A(L) showed promising anti-inflammatory activity by targeting MD2, and the amino acid domain 7-13 was an important area that binds with MD2 and also an anti-inflammatory active region. LK2(6)A(L) and IS-7 may be potential new treatments for ALI and other acute inflammatory diseases.

Effects of molecular weight of chitosan on anti-inflammatory activity and modulation of intestinal microflora in an ulcerative colitis model

This study investigated the therapeutic effects and mechanisms of chitosans (CSs) with different molecular weights on ulcerative colitis (UC). Three size classes of CSs (Mw ≤ 3, 50, and 200 kDa) were used in this study. The effect of large CSs (Mw ≤ 200 kDa) on UC was the best, followed by that of medium CSs (Mw ≤ 50 kDa), and that of small CSs (Mw ≤ 3 kDa) was the least in the LPS-induced Raw 264.7 cell model and DSS-induced UC mice model. The therapeutic mechanisms of three CSs are related to anti-oxidation, anti-inflammation, and regulation of immunoglobulin and intestinal flora by attenuating body weight loss, decreasing the disease activity index (DAI) and MPO activity, suppressing proinflammatory cytokines and IgG levels, down-regulating the level of oxidative stress, increasing anti-inflammatory cytokines, SOD activity and Prevotellaceae_UCG-001 levels, and reducing the abundance of Proteobacteria, Actinobacteria, and Escherichia-Shigella. In general, the molecular weight of CSs influences their efficacy against UC. CSs with an optimal molecular weight demonstrate good development prospects for ameliorating UC.

Discovery and Development of Inflammatory Inhibitors from 2-Phenylchromonone (Flavone) Scaffolds

Flavonoids are compounds based on a 2-phenylchromonone scaffold. Flavonoids can be divided into flavonoids, flavonols, dihydroflavones, anthocyanins, chalcones and diflavones according to the oxidation degree of the central tricarbonyl chain, the connection position of B-ring (2-or 3-position), and whether the tricarbonyl chain forms a ring or not. There are a variety of biological activities about flavonoids, such as anti-inflammatory activity, anti-oxidation and anti-tumor activity, and the antiinflammatory activity is apparent. This paper reviews the anti-inflammatory activities and mechanisms of flavonoids and their derivatives reported in China and abroad from 2011 till date (2011-2020), in order to find a good drug scaffold for the study of anti-inflammatory activities.

Anti-inflammatory effects of Zhishi and Zhiqiao revealed by network pharmacology integrated with molecular mechanism and metabolomics studies

BACKGROUND

The inflammatory response has a complex pathogenesis; thus, it is a critical contributor to the development and complication of many diseases. Zhishi and Zhiqiao are famous Citrus herbal medicines that are rich in bioactive phenolic constituents with multiple anti-inflammatory activities.

PURPOSE

Establishment of a multi-component-target-pathway network strategy to investigate the usage of Zhishi and Zhiqiao on inflammatory diseases can provide a reference for mechanisms of traditional Chinese medicine (TCM).

STUDY DESIGN

A multi-component-target-pathway network strategy was constructed to elucidate the various antiinflammatory effects of Zhishi and Zhiqiao by integrating multi-constituent determination, network pharmacology, molecular mechanisms in cells and integrated metabolomics in animals.

METHODS

Based on the quantitatively determined global and characteristic chemical profiles of Zhishi and Zhiqiao, the component-target-pathway network was predicted by network pharmacology coupled with text mining and docking. The potential antiinflammatory mechanism of the various components in Zhishi and Zhiqiao were verified using LPS-induced inflammatory responses in RAW 264.7 cells. The different metabolic regulating effects of Zhishi and Zhiqiao against an LPS-induced inflammation model were investigated using a plasma metabolomics strategy.

RESULTS

The molecular mechanism of Zhishi mainly suppressed the MAPK signaling pathway, whereas Zhiqiao emphasized the PPAR-AKT signaling pathways simultaneously to block the inflammatory process. Meanwhile, Zhishi and Zhiqiao both exhibited an anti-inflammatory effect by inhibiting the NF-κB signaling pathway to reduce the production of inflammatory mediators. In the metabolomics study, Zhishi and Zhiqiao exhibited variant corrections of the disordered metabolic pathways through amino acid metabolism, glycometabolism and lipid metabolism.

CONCLUSION

All of these results indicate that Zhishi and Zhiqiao, in a diversified mixture, exert their anti-inflammatory effect through variant pathways. These findings can assist in developing the use of Zhishi and Zhiqiao for inflammatory diseases.

Anti-inflammatory and associated analgesic activities of HPLC standardized alcoholic extract of known ayurvedic plant Schleichera oleosa

ETHNOPHARMACOLOGICAL RELEVANCE

Schleichera oleosa (Lour.) Oken. commonly known as 'Koshamra' in Ayurveda is a tropical tree readily found in Asia and is used to treat pain and rheumatism, as traditional medicine in different parts of India. However, scientific evidences to justify these claims are lacking. Considering the traditional use of S.oleosa and the lack of information about its pharmacological properties, we investigated the anti-inflammatory and analgesic effect of the alcoholic extract of S.oleosa (SE) against different animal models in rodents.

MATERIALS AND METHODS

The anti-inflammatory activity was evaluated against carrageenan induced paw edema and TPA (12-O-tetradecanoylphorbol-13-acetate) induced ear edema. To assess the mechanism of anti-inflammatory action the extract was tested against different phlogistic agents like histamine, serotonin, bradykinin and, prostaglandin E2. The analgesic activity was assessed against formalin induced pain.

RESULTS

The ethanolic extract of S. oleosa bark, did not exhibited any signs of toxicity up to a dose of 2000mg/kg. The extract significantly inhibited increase in paw edema and ear edema. A percent reduction of 60.84% was found against carrageenan induced paw edema by 400mg/kg dose of SE. The extract was effective against edema induced by serotonin, histamine and PGE₂. In formalin test the extract inhibited both the neurogenic 1st and mainly the inflammatory 2nd phase. Significant reduction in tissue levels of inflammatory mediators was also observed (p<0.05 for NO and p<0.01 for MDA). The extract showed presence of potent analgesic and anti-inflammatory compounds lupeol, lupeol acetate, betulin and betulinic acid on HPLC analysis which can be held responsible for its studied biological activity.

CONCLUSIONS

The results suggest that SE is effective in inflammatory processes and targets multiple mediators of inflammation. Its action is markedly influenced by the inhibition of neutrophil migration, anti-oxidant action and reduction in inflamed tissue.

Effects of volatile oils of Angelica sinensis on an acute inflammation rat model

Context Despite several pharmacological studies of volatile oils of Angelica sinensis (Oliv.) Diels (Umbelliferae) (VOAS), its anti-inflammatory mechanism remains unknown. Objective The study investigates the effects of VOAS on the lipopolysaccharide (LPS)-induced acute inflammation rat model and analyzes its possible anti-inflammatory mechanisms. Materials and methods Fourty rats were randomly divided into the control, model, VOAS and dexamethasone (Dex) groups. The VOAS and Dex groups were given VOAS (0.176 mL/kg) and Dex (40 μg/kg), respectively. Rats in all groups except the control group were intraperitoneally injected with LPS (100 μg/kg), their exterior behaviour and liver pathological changes were observed, and the level of white blood cell (WBC), the number of neutrophils (NE)%, glutamic oxalacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), alkaline phosphatase (ALP), tumour necrosis factor (TNF-α), interleukin (IL)-1β, IL-6, IL-10, histamine (HIS), 5-hydroxytryptamine (5-HT), nitric oxide (NO), prostaglandin E2 (PGE2), inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) were detected. Results Compared with the model group, VOAS and Dex significantly accelerated the recovery of the exterior behaviour, the liver pathological changes of rats, and increased the level of IL-10, but decreased the level of WBC, NE%, GOT, GPT, ALP, TNF-α, IL-1β, IL-6, HIS, 5-HT, NO, PGE2, iNOS and COX-2 (p < 0.05). Conclusion VOAS exhibits anti-inflammatory and liver protection effects by inhibiting the secretion of the pro-inflammatory cytokines (TNF-α, IL-1β and IL-6), the inflammatory mediators (HIS, 5-HT, PGE2 and NO), the inflammation-related enzymes (iNOS and COX-2), as well as promoting the production of the anti-inflammatory cytokines IL-10.