Pterostilbene Ameliorates DSS-Induced Intestinal Epithelial Barrier Loss in Mice via Suppression of the NF-κB-Mediated MLCK-MLC Signaling Pathway

Potential interventions and interactions of bioactive polyphenols and functional polysaccharides to alleviate inflammatory bowel disease - A review

Inflammatory bowel disease is a multifaceted condition that is influenced by nutritional, microbial, environmental, genetic, psychological, and immunological factors. Polyphenols and polysaccharides have gained recognition for their therapeutic potential. This review emphasizes the biological effects of polyphenols and polysaccharides, and explores their antioxidant, anti-inflammatory, and microbiome-modulating properties in the management of inflammatory bowel disease (IBD). However, polyphenols encounter challenges, such as low stability and low bioavailability in the colon during IBD treatment. Hence, polysaccharide-based encapsulation is a promising solution to achieve targeted delivery, improved bioavailability, reduced toxicity, and enhanced stability. This review also discusses the significance of covalent and non-covalent interactions, and simple and complex encapsulation between polyphenols and polysaccharides. The administration of these compounds in appropriate quantities has proven beneficial in preventing the development of Crohn's disease and ulcerative colitis, ultimately leading to the management of IBD. The use of polyphenols and polysaccharides has been found to reduce histological scores and colon injury associated with IBD, increase the abundance of beneficial microbes, inhibit the development of colitis-associated cancer, promote the production of microbial end-products, such as short-chain fatty acids (SCFAs), and improve anti-inflammatory properties. Despite the combined effects of polyphenols and polysaccharides observed in both in vitro and in vivo studies, further human clinical trials are needed to comprehend their effectiveness on inflammatory bowel disease.

Natural plant polyphenols contribute to the ecological and healthy swine production

The absence of trace amounts of natural bioactive compounds with important biological activities in traditional dietary models for global farm animals, coupled with an incomplete theoretical system for animal nutrition, has led to unbalanced and inadequate animal nutrition. This deficiency has adversely impacted animal health and the ecological environment, presenting formidable challenges to the advancement of the swine breeding industry in various countries around the world toward high-quality development. Recently, due to the ban of antibiotics for growth promotion in swine diets, botanical active compounds have been extensively investigated as feed additives. Polyphenols represent a broad group of plant secondary metabolites. They are natural, non-toxic, pollution-free, and highly reproducible compounds that have a wide range of physiological functions, such as antioxidant, anti-inflammatory, immunomodulatory, antiviral, antibacterial, and metabolic activities. Accordingly, polyphenols have been widely studied and used as feed additives in swine production. This review summarizes the structural characteristics, classification, current application situation, general properties of polyphenols, and the latest research advances on their use in swine production. Additionally, the research and application bottlenecks and future development of plant polyphenols in the animal feed industry are reviewed and prospected. This review aims to stimulate the in-depth study of natural plant polyphenols and the research and development of related products in order to promote the green, healthy, and high-quality development of swine production, while also providing ideas for the innovation and development in the theoretical system of animal nutrition.

The mechanisms behind heatstroke-induced intestinal damage

With the frequent occurrence of heatwaves, heatstroke (HS) is expected to become one of the main causes of global death. Being a multi-organized disease, HS can result in circulatory disturbance and systemic inflammatory response, with the gastrointestinal tract being one of the primary organs affected. Intestinal damage plays an initiating and promoting role in HS. Multiple pathways result in damage to the integrity of the intestinal epithelial barrier due to heat stress and hypoxia brought on by blood distribution. This usually leads to intestinal leakage as well as the infiltration and metastasis of toxins and pathogenic bacteria in the intestinal cavity, which will eventually cause inflammation in the whole body. A large number of studies have shown that intestinal damage after HS involves the body's stress response, disruption of oxidative balance, disorder of tight junction proteins, massive cell death, and microbial imbalance. Based on these damage mechanisms, protecting the intestinal barrier and regulating the body's inflammatory and immune responses are effective treatment strategies. To better understand the pathophysiology of this complex process, this review aims to outline the potential processes and possible therapeutic strategies for intestinal damage after HS in recent years.

AHR activation relieves deoxynivalenol-induced disruption of porcine intestinal epithelial barrier functions

Mycotoxins are ubiquitous natural pollutants that pose a serious threat to public health. Deoxynivalenol (DON) as one of the most prominent mycotoxins has a noticeable adverse effect on intestinal barrier function, which depends on the intestinal barrier integrity. However, the potential mechanisms and effective therapeutic strategies remain unclear. Aryl hydrocarbon receptor (AHR) has been implicated in the modulation of intestinal barrier function and inflammation. The study aims to investigate the unique role of AHR in mediating DON-induced intestinal epithelial barrier function. In the current study, we revealed that DON triggered mitochondrial structural damage and functional impairment, leading to oxidative stress and apoptosis in porcine jejunal epithelial cells (IPEC-J2). DON altered the integrity of IPEC-J2 cells by disrupting the distribution and function of tight junction proteins. Additionally, DON activated TNF-α/NF-κB/MLCK signaling pathway, thereby eliciting inflammatory response. Notably, DON inhibited AHR nuclear translocation and attenuated xenobiotic response element promoter activity and its target genes. However, overexpression of AHR mitigated DON-induced disruption of intestinal epithelial barrier functions by suppressing TNF-α/NF-κB/MLCK pathway in IPEC-J2 cells. Our findings indicate that AHR regulates intestinal epithelial barrier function and therefore is a novel therapeutic molecule for intestinal disorders.

Structural characteristics of a polysaccharide from Armillariella tabescens and its protective effect on colitis mice via regulating gut microbiota and intestinal barrier function

A new polysaccharide fraction (ATP) was obtained from Armillariella tabescens mycelium. Structural analysis suggested that the backbone of ATP was →4)-α-D-Glcp(1 → 2)-α-D-Galp(1 → 2)-α-D-Glcp(1 → 4)-α-D-Glcp(1→, which branched at O-3 of →2)-α-D-Glcp(1 → and terminated with T-α-D-Glcp or T-α-D-Manp. Besides, ATP significantly alleviated ulcerative colitis (UC) symptoms and inhibited the production of pro-inflammation cytokines (IL-1β, IL-6). Meanwhile, ATP could improve colon tissue damage by elevating the expression of MUC2 and tight junction proteins (ZO-1, occludin and claudin-1) levels and enhance intestinal barrier function through inhibiting the activation of MMP12/MLCK/p-MLC2 signaling pathway. Further studies exhibited that ATP could increase the relative abundance of beneficial bacteria such as f. Muribaculacese, g. Muribaculaceae, and g. Alistips, and decrease the relative abundance of g. Desulfovibrio, g. Colidextribacter, g. Ruminococcaceae and g.Oscillibacter, and regulate the level of short-chain fatty acids. Importantly, FMT intervention with ATP-derived microbiome certified that gut microbiota was involved in the protective effects of ATP on UC. The results indicated that ATP was potential to be further developed into promising therapeutic agent for UC.

Pterostilbene Alleviates Dextran Sodium Sulfate (DSS)-Induced Intestinal Barrier Dysfunction Involving Suppression of a S100A8-TLR-4-NF-κB Signaling Cascade

Intestinal barrier hemostasis is the key to health. As a resveratrol analogue, pterostilbene (PT) has been reported to prevent dextran sodium sulfate (DSS)-induced intestinal barrier dysfunction mainly associated with the intestinal NF-κB signaling pathway. However, the exact underlying mechanisms are not yet well-defined yet. In this study, we performed RNA-sequencing analysis and unexpectedly found that alarmin S100A8 sensitively responded to DSS-induced intestinal injury. Accordingly, histologic assessments suggested that the high expression of S100A8 was accompanied by increased intestinal infiltration of macrophages, upregulated intestinal epithelial Toll-like receptor 4 (TLR-4), and activated NF-κB signaling pathway. Interestingly, the above phenomena were effectively counteracted upon the addition of PT. Furthermore, by using a coculture system of macrophage THP-1 cells and HT-29 colon cells, we identified macrophage-secreted S100A8 activated intestinal epithelial NF-κB signaling pathway through TLR-4. Taken together, these findings suggested that PT ameliorated DSS-induced intestinal barrier injury through suppression of the macrophage S100A8-intestinal epithelial TLR-4-NF-κB signaling cascade.

Forsythiaside A alleviates acute lung injury by inhibiting inflammation and epithelial barrier damages in lung and colon through PPAR-γ/RXR-α complex

INTRODUCTION

Acute lung injury (ALI) is a lung disease characterized by inflammation and still requires further drug development. Forsythiaside A as the active compound of Forsythiae Fructus has the therapeutic potential for ALI.

OBJECTIVE

To investigate the mechanism of forsythiaside A in treating ALI through PPAR-γ and its conjugate RXR-α based on gut-lung axis.

METHODS

This study constructed in vitro and in vivo injury models using LPS and TNF-α. Forsythiaside A was used for the drug treatment, and RXR-α inhibitor UVI3003 was used to interfere with PPAR-γ/RXR-α complexes in the cells. HE staining was used for histopathological examination. Serum endotoxin contents were determined using limulus lysate kit. IHC staining and Western blot were conducted to assess the protein expressions. ELISA was applied to examine the content of pro-inflammatory cytokines in the cell supernatants. The protein interactions were analyzed via CO-IP.

RESULTS

In vivo results showed that forsythiaside A regulated PPAR-γ/RXR-α and inhibited TLR4/MAPK/NF-κB and MLCK/MLC2 signal pathways, thus inhibiting inflammation and epithelial barrier damages of lung and colon in ALI mice induced by intratracheal LPS. PPAR-γ/RXR-α were promoted by forsythiaside A in lungs, whereas inhibited by forsythiaside A in colons. Additionally, in vitro results showed that forsythiaside A suppressed inflammation and epithelial barrier damages in macrophages and lung/colon epithelial cells, by manipulating PPAR-γ/RXR-α to suppress the LPS- and TNF-α-induced activation of TLR4/MAPK/NF-κB and NF-κB/MLCK/MLC2 signal pathways. Moreover, further mechanism study indicated that forsythiaside A showed a cell-specific regulatory effect on PPAR-γ/RXR-α complex. Specifically, the PPAR-γ/RXR-α protein interactions were promoted by forsythiaside A in LPS-induced macrophages RAW264.7 and TNF-α-induced lung epithelial cells A549, but inhibited by forsythiaside A in TNF-α-induced colon epithelial cells SW620.

CONCLUSION

In the treatment of ALI, Forsythiaside A inhibited inflammation and epithelial barrier damages of lung and colon through its regulation on PPAR-γ/RXR-α complex.

Polystyrene microplastic-induced oxidative stress triggers intestinal barrier dysfunction via the NF-κB/NLRP3/IL-1β/MCLK pathway

Emerging evidence has demonstrated the association between microplastics (MPs) with a diameter of <5 mm and the risk of intestinal diseases. However, the molecular mechanisms contributing to MP-induced intestinal barrier dysfunction have not been fully appreciated. In this study, C57BL/6 J mice were exposed to polystyrene microplastics (PS-MPs, 0.2, 1 or 5 μm) at 1 mg/kg body weight daily by oral gavage for 28 days. We found that PS-MPs exposure induced oxidative stress and inflammatory cell infiltration in mice colon, leading to an increased expression of pro-inflammatory cytokine. Moreover, there were an increase in intestinal permeability and decrease in mucus secretion, accompanied by downregulation of tight junction (TJ)-related zonula occluden-1 (ZO-1), occluding (OCLN) and claudin-1 (CLDN-1) in mice colon. Especially, 5 μm PS-MPs (PS5)-induced intestinal epithelial TJ barrier damage was more severe than 0.2 μm PS-MPs (PS0.2) and 1 μm PS-MPs (PS1). In vitro experiments indicated that PS5-induced oxidative stress upregulated the expression of nuclear factor kappa B (NF-κB), nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome, and myosin light chain kinase (MLCK). Meanwhile, pre-treatment with the antioxidant NAC, NLRP3 inhibitor MCC950 and MLCK inhibitor ML-7 considerably reduced PS5-triggered reactive oxygen species (ROS) production and inflammatory response, inhibited the activation of the NF-κB/NLRP3/MLCK pathway, and upregulated ZO-1, OCLN and CLDN-1 expression in Caco-2 cells. Taken together, our study demonstrated that PS-MPs cause intestinal barrier dysfunction through the ROS-dependent NF-κB/NLRP3/IL-1β/MLCK pathway.

Regulation of the intestinal flora using polysaccharides from Callicarpa nudiflora Hook to alleviate ulcerative colitis and the molecular mechanisms involved

Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD) that cannot be completely cured by current treatments. C. nudiflora Hook has antibacterial, anti-inflammatory, and hemostatic biological functions; however, the therapeutic role of C. nudiflora Hook or its extracts in IBD remains poorly understood. In this study, we extracted and purified three fractions of C. nudiflora Hook polysaccharides by hydroalcohol precipitation method, which were named as CNLP-1, CNLP-2 and CNLP-3, respectively. CNLP-2, the main component of the polysaccharides of C. nudiflora Hook is an pyranose type acidic polysaccharide composed of Fuc, Rha, Ara, Gal, Glc, Xyl, Man, Gal-UA and Glc-UA, with an Mn of 15.624 kDa; Mw of 31.375 kDa. CNLP-2 was found to have a smooth lamellar structure as observed by scanning electron microscopy. To investigate the effect of CNLP-2 (abbreviated to CNLP) on dextran sodium sulfate (DSS)-induced UC mice and its mechanism of action, we treated DSS-induced UC mice by administering CNLP at a dose of 100 mg/kg every other day. The results of the study showed that CNLP alleviated the clinical symptoms such as body weight (BW) loss, pathological damage, and systemic inflammation. The mechanism may be through the regulation of intestinal flora and its metabolism, which in turn affects the expression of NF-κB/MAPK pathway-related proteins through the metabolites of intestinal flora to further alleviate inflammation and ultimately improve the intestinal barrier function in UC mice. In conclusion, CNLP has great potential for the treatment of IBD.

Mechanism of Intestinal Epithelial Absorption and Electrophysiological Regulation of the Shrimp Peptide QMDDQ

We investigated the absorption mechanism of the shrimp peptide QMDDQ in small intestines, explored its physiological function in inhibiting neuronal hyperactivity, and verified its entry into the brain in vivo to display functional activity. The everted rat sac model and a Caco-2 paracellular absorption monolayer model were used, indicating that QMDDQ has a good absorption capacity with an apparent permeability coefficient (Papp) > 1 × 10-6 cm/s and the absorption of QMDDQ was concentration-dependent. When the concentration of QMDDQ was 1 mM and the transport time was 180 min, the highest absorption concentration of QMDDQ was 41.17 ± 3.48 μM (P < 0.05). The myosin light-chain kinase (MLCK)-specific inhibitor ML-7 and activator MPA, Western blotting, and immunofluorescence results showed that QMDDQ absorption takes place by mediating the MLCK-p-MLCK-MLC signaling pathway, reversibly opening the zonula occludens-1 (ZO-1), occludin in tight junctions (TJs), upregulating claudin-2 expression, and reaching targets through blood to inhibit neuronal overactivity. Results of fluorescence imaging in vivo verified that QMDDQ could enter the brain 4 h after oral administration. The results provide a theoretical foundation for the mechanism of paracellular absorption of active peptides and a starting point for the development of functional foods for Alzheimer's disease intervention.

Reactive oxygen species-responsive nanocarrier ameliorates murine colitis by intervening colonic innate and adaptive immune responses

Ulcerative colitis (UC) is a chronic or relapsing inflammatory disease with limited therapeutic outcomes. Pterostilbene (PSB) is a polyphenol-based anti-oxidant that has received extensive interest for its intrinsic anti-inflammatory and anti-oxidative activities. This work aims to develop a reactive oxygen species (ROS)-responsive, folic acid (FA)-functionalized nanoparticle (NP) for efficient PSB delivery to treat UC. The resulting PSB@NP-FA had a nano-scaled diameter of 231 nm and a spherical shape. With ROS-responsive release and ROS-scavenging properties, PSB@NP could effectively scavenge H2O2, thereby protecting cells from H2O2-induced oxidative damage. After FA modification, the resulting PSB@NP-FA could be internalized by RAW 264.7 and Colon-26 cells efficiently and preferentially localized to the inflamed colon. In dextran sulfate sodium (DSS)-induced colitis models, PSB@NP-FA showed a prominent ROS-scavenging capacity and anti-inflammatory activity, therefore relieving murine colitis effectively. Mechanism results suggested that PSB@NP-FA ameliorated colitis by regulating dendritic cells (DCs), promoting macrophage polarization, and regulating T cell infiltration. Both innate and adaptive immunity were involved. More importantly, the combination of the PSB and dexamethasone (DEX) enhanced the therapeutic efficacy of colitis. This ROS-responsive and ROS-scavenging nanocarrier represents an alternative therapeutic approach to UC. It can also be used as an enhancer for classic anti-inflammatory drugs.

Chlorogenic acid combined with epigallocatechin-3-gallate mitigates D-galactose-induced gut aging in mice

Chlorogenic acid (CGA) and epigallocatechin-3-gallate (EGCG) are major polyphenolic constituents of coffee and green tea with beneficial health properties. In this study, we evaluated the gut protecting effect of CGA and EGCG, alone or in combination, on D-galactose-induced aging mice. CGA plus EGCG more effectively improved the cognition deficits and protected the gut barrier function, compared with the agents alone. Specifically, CGA plus EGCG prevented the D-galactose mediated reactive oxygen species accumulation by increasing the total antioxidant capacity, reducing the levels of malondialdehyde, and suppressing the activity of the antioxidant enzymes superoxide dismutase and catalase. In addition, supplementation of CGA and EGCG suppressed gut inflammation by reducing the levels of the proinflammatory cytokines TNFα, IFNγ, IL-1β and IL-6. Moreover, CGA and EGCG modulated the gut microbiome altered by D-galactose. For instance, CGA plus EGCG restored the Firmicutes/Bacteroidetes ratio of the aging mice to control levels. Furthermore, CGA plus EGCG decreased the abundance of Lactobacillaceae, Erysipelotrichaceae, and Deferribacteraceae, while increased the abundance of Lachnospiraceae, Muribaculaceae, and Rikenellaceae, at the family level. In conclusion, CGA in combination with EGCG ameliorated the gut alterations induced by aging, in part, through antioxidant and anti-inflammatory effects, along with its gut microbiota modulatory capacity.

Molecular Mechanisms Associated with Protecting IEC-6 Cells from Acrylamide-Induced Tight Junction Damage by Ganoderma atrum Polysaccharide

SCOPE

The previous in vivo studies show Ganoderma atrum polysaccharide (PSG-F₂ ) has a protective effect against the acrylamide (AA)-induced intestinal oxidative damage in rats. Now, this study aims to explore the protective mechanism with IEC-6 cell model.

METHODS AND RESULTS

Based on RNA Sequencing (RNA-Seq), the study screens MAPK signaling pathway as one of the most crucial pathways for pretreatment with PSG-F₂   against AA-induced damage in IEC-6 cells. In total, six key MAPK signaling pathway-related proteins (p-P38/P38, p-ERK/ERK, and p-JNK/JNK), and three tight junction key proteins (Zonula Occludens protein-1, Claudin-1, and Occludin) are detected by Western blot and immunofluorescence, which verify the RNA-Seq data. Moreover, PD98059 interference inhibits critical proteins in the MAPK signaling pathway, thus uncovering the precise molecular mechanisms of MAPK/ERK signaling pathway involve in the protective effects of PSG-F₂ against AA-induced intestinal barrier damage.

CONCLUSION

These findings confirm that PSG-F₂ can be used as a daily dietary supplement to protect the intestinal cells from damage caused by thermal processing hazards AA.

Lead exposure exacerbates adverse effects of HFD on metabolic function via disruption of gut microbiome, leading to compromised barrier function and inflammation

PURPOSE

The toxicity of lead (Pb) has been intensively studied, while the adverse effects in the population on a high-fat diet (HFD) remain unclear. This study compared the different biologic effects of Pb in CHOW and HFD-fed mice and investigated the important role that gut microbiota may play.

METHODS

C57BL/6 mice were fed a CHOW diet and HFD with or without 1 g/L Pb exposure through drinking water for 8 weeks. Using oral glucose tolerance test, histopathological observation, real-time fluorescence quantitative PCR, enzyme-linked immunosorbent assay, and 16S high-throughput sequencing to compare the Pb toxicity, fecal microbiota transplantation was conducted to investigate the key role of gut microbiota.

RESULTS

The metabolic disorders induced by HFD were aggravated by chronic Pb intake, and HFD exacerbated the Pb accumulation in the colon by 96%, 32% in blood, 27% in the liver, and 142% in tibiae. Concomitantly, Pb induced more serious colonic injury, further disturbing the composition of gut microbiota in the HFD-fed mice. Moreover, altered fecal microbiota by HFD and Pb directly mediated metabolic disorders and colonic damage in recipient mice, which emphasized the importance of gut microbiota.

CONCLUSION

These findings indicated that the population with HFD has lower resistance and would face more security risks under Pb pollution, and pointed out the importance of assessing the health impacts of food contaminants in people with different dietary patterns.

Pterostilbene Confers Protection against Diquat-Induced Intestinal Damage with Potential Regulation of Redox Status and Ferroptosis in Broiler Chickens

Oxidative stress causes damage to macromolecules, including proteins, DNA, and lipid, and has been recognized as a crucial driver of the onset and progression of several intestinal disorders. Pterostilbene, one of the natural antioxidants, has attracted considerable attention owing to its multiple biological activities. In the present study, we established an oxidative stress model in broiler chickens via injection with diquat to investigate whether pterostilbene could attenuate diquat-induced intestinal damage and reveal the underlying mechanisms. We found that diquat-induced decreases in the activities of superoxide dismutase and glutathione peroxidase and the level of reduced glutathione and the increase in hydrogen peroxide content in plasma and jejunum were significantly alleviated by pterostilbene (P < 0.05). Pterostilbene supplementation also decreased intestinal permeability and jejunal apoptosis rate, improved jejunal villus height and the ratio of villus height to crypt depth, and promoted the transcription and translation of jejunal tight junction proteins occludin and zona occludens 1 in diquat-challenged broilers (P < 0.05). Furthermore, pterostilbene reversed diquat-induced mitochondrial injury in the jejunum, as indicated by the decreased reactive oxygen species level and elevated activities of superoxide dismutase 2 and mitochondrial respiratory complexes (P < 0.05). Importantly, administering pterostilbene maintained iron homeostasis, inhibited lipid peroxidation, and regulated the expression of the markers of ferroptosis in the jejunum of diquat-exposed broilers (P < 0.05). The nuclear factor erythroid 2-related factor 2 signaling pathway in the jejunum of diquat-exposed broilers was also activated by pterostilbene (P < 0.05). In conclusion, our study provides evidence that pterostilbene alleviates diquat-induced intestinal mucosa injury and barrier dysfunction by strengthening antioxidant capacity and regulating ferroptosis of broiler chickens.

Pterostilbene attenuates intrauterine growth retardation-induced colon inflammation in piglets by modulating endoplasmic reticulum stress and autophagy

Background

Endoplasmic reticulum (ER) stress and autophagy are implicated in the pathophysiology of intestinal inflammation; however, their roles in intrauterine growth retardation (IUGR)-induced colon inflammation are unclear. This study explored the protective effects of natural stilbene pterostilbene on colon inflammation using the IUGR piglets and the tumor necrosis factor alpha (TNF-α)-treated human colonic epithelial cells (Caco-2) by targeting ER stress and autophagy.

Results

Both the IUGR colon and the TNF-α-treated Caco-2 cells exhibited inflammatory responses, ER stress, and impaired autophagic flux (P < 0.05). The ER stress inducer tunicamycin and the autophagy inhibitor 3-methyladenine further augmented inflammatory responses and apoptosis in the TNF-α-treated Caco-2 cells (P < 0.05). Conversely, pterostilbene inhibited ER stress and restored autophagic flux in the IUGR colon and the TNF-α-treated cells (P < 0.05). Pterostilbene also prevented the release of inflammatory cytokines and nuclear translocation of nuclear factor kappa B p65, reduced intestinal permeability and cell apoptosis, and facilitated the expression of intestinal tight junction proteins in the IUGR colon and the TNF-α-treated cells (P < 0.05). Importantly, treatment with tunicamycin or autophagosome-lysosome binding inhibitor chloroquine blocked the positive effects of pterostilbene on inflammatory response, cell apoptosis, and intestinal barrier function in the TNF-α-exposed Caco-2 cells (P < 0.05).

Conclusion

Pterostilbene mitigates ER stress and promotes autophagic flux, thereby improving colon inflammation and barrier dysfunction in the IUGR piglets and the TNF-α-treated Caco-2 cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00780-6.

Dexmedetomidine inhibits abnormal muscle hypertrophy of myofascial trigger points via TNF-α/ NF-κB signaling pathway in rats

Myofascial pain syndrome (MPS) is a chronic pain disorder with inflammation-related primarily characterized by the presence of myofascial trigger points (MTrPs). Myocyte enhancer factor 2C (MEF2C) is involved in the occurrence of a variety of skeletal muscle diseases. However, it is not yet clear if MEF2C is involved in MTrPs. The purpose of this study was to investigate whether MEF2C was involved in the inflammatory pathogenesis of MTrPs. In the present study, we used RNA sequencing (RNA-seq) to compare the differential expression of myocyte enhancer factor 2C (MEF2C) in healthy participants and MTrPs participants. The widely used rat MTrPs model was established to research the upstream and downstream regulatory mechanism of MEF2C and found that MEF2C was significantly increased in patients with MTrPs. Dexmedetomidine (Dex) was injected intramuscularly in the MTrPs animal to assess its effects on MEF2C. The expression of MEF2C protein and mRNA in skeletal muscle of rats in the MTrPs group were up-regulated. In addition, the expression of TNF- α, p-P65, MLCK, and Myocilin (MyoC) was up-regulated and the mechanical pain threshold was decreased. Peripheral TNF- α injection significantly decreased the mechanical pain threshold and increased the expression of p-P65, MLCK, MEF2C, and MyoC in healthy rats. Maslinic acid increased the mechanical pain threshold and inhibited the expression of p-P65, MLCK, MEF2C, and MyoC. In addition, peripheral injection of DEX in MTrPs rats also inhibited the expression of TNF- α, p-P65, MLCK, MEF2C, and MyoC. These results suggest that MEF2C is involved in the inflammatory pathogenesis of MTrPs and DEX serves as a potential therapeutic strategy for the treatment of MPS.

Potential of natural products in the treatment of irritable bowel syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is a kind of functional bowel disease that is characterized by bellyache, abdominal distension, and diarrhea. Although not life-threatening, IBS has a long course and recurrent attacks and seriously affects the life quality of patients. Current drugs for treating IBS possess remarkable limitations, such as limited efficacy and severe adverse reactions. Therefore, developing novel medications to treat IBS is quite essential, and natural products may be a substantial source.

PURPOSE

This is the first systematic review elaborating the recent advancement of natural products as potential drugs for the therapy of IBS.

METHODS

A comprehensive retrieval of studies was carried out in scientific databases including PubMed, Web of Science, Elsevier, and CNKI. By using ("irritable bowel syndrome" OR "IBS") AND ("natural product" OR "natural compound" OR "phytochemical") as keywords, the eligible studies were screened, and the relevant information about therapeutic action and mechanism of natural products treating IBS was extracted.

RESULTS

Natural products against IBS consisted of four categories, namely, terpenoids, flavonoids, alkaloids, and phenols. Furthermore, the underlying mechanisms for natural products treating IBS were tightly associated with increased TJs and mucus protein expression, regulation of the brain-gut axis and gut microbiota structure, and inhibition of inflammatory response and intestinal mucosal damage.

CONCLUSION

Natural products could be extremely prospective candidate drugs used to treat IBS, and further preclinical and clinical researches are needed to guarantee their efficacy and safety.

Therapeutic effects and mechanisms of plant-derived natural compounds against intestinal mucositis

Intestinal mucositis is a clinically related adverse reaction of antitumor treatment. Majority of patients receiving high-dose chemical therapy, radiotherapy, and bone-marrow transplant suffer from intestinal mucositis. Clinical manifestations of intestinal mucositis mainly include pain, body-weight reduction, inflammatory symptom, diarrhea, hemoproctia, and infection, which all affect regular nutritional input and enteric function. Intestinal mucositis often influences adherence to antitumor treatment because it frequently restricts the sufferer’s capacity to tolerate treatment, thus resulting in schedule delay, interruption, or premature suspension. In certain circumstances, partial and general secondary infections are found, increasing the expenditures on medical care and hospitalization. Current methods of treating intestinal mucositis are provided, which do not always counteract this disorder. Against this background, novel therapeutical measures are extremely required to prevent and treat intestinal mucositis. Plant-derived natural compounds have lately become potential candidates against enteric injury ascribed to the capacity to facilitate mucosal healing and anti-inflammatory effects. These roles are associated with the improvement of intestinal mucosal barrier, suppression of inflammatory response and oxidant stress, and modulation of gut microflora and immune system. The present article aims at systematically discussing the recent progress of plant-derived natural compounds as promising treatments for intestinal mucositis.

Differential Protective Effect of Resveratrol and Its Microbial Metabolites on Intestinal Barrier Dysfunction is Mediated by the AMPK Pathway

The effectiveness of resveratrol (RES) on intestinal barrier dysfunction and colitis has been extensively studied. However, the specific effects of its microbial metabolites on gut barrier function remain unclear. Hence, we compared the protective effects of RES and its microbial metabolites dihydroresveratrol (DHR) and 3-(4-hydroxyphenyl)-propionic acid (4HPP) against intestinal barrier injury and colitis. Only 4HPP and RES significantly reduced paracellular permeability and the secretion of proinflammatory cytokines in lipopolysaccharides (LPS)-treated intestinal Caco-2 cells, which was consistent with the upregulation in tight junction (TJ) proteins. Furthermore, RES and 4HPP ameliorated intestinal barrier dysfunction and colonic inflammation in colitis mice, while DHR did not. In particular, the expressions of intestinal TJ proteins and Muc2 were restored by RES and 4HPP. The molecular mechanism involved the adenosine monophosphate-activated protein kinase (AMPK)-mediated activation of CDX2 and the regulation of the SIRT1/NF-κB pathway. These findings provide new insights into understanding the protective effects of RES against intestinal barrier damage and colitis.

Chronic Exposure to Environmentally Relevant Concentrations of Microcystin-Leucine Arginine Causes Lung Barrier Damage through PP2A Activity Inhibition and Claudin1 Ubiquitination

Microcystin-leucine arginine (MC-LR), ubiquitous in water and food, is a threat to public health. In the present study, after C57BL/6J mice were fed with environmental concentrations of MC-LR (0, 1, 30, 60, 90, and 120 μg/L) for 6, 9, and 12 months, it was found that MC-LR could enter into mouse lung tissues and cause microstructural damage, as shown by western blotting and HE staining. Electron microscopy examination showed that MC-LR could damage the lung barrier by disruption of the tight junctions, which was confirmed by the decreased expression of tight junction markers, including Occludin, Claudin1, and ZO-1. In addition, MC-LR also increased the ubiquitination of Claudin1, indicating that MC-LR could disrupt tight junctions by promoting the degradation of Claudin1. Furthermore, MC-LR increased the levels of TNF-α and IL-6 in mouse lung tissues, leading to pneumonia. Importantly, pretreatment with PP2A activator D-erythro-sphingosine (DES) was found to significantly alleviate MC-LR-induced decrease of Occludin and Claudin1 by inhibiting the P-AKT/Snail pathway in vitro. Together, this study revealed that chronic exposure to MC-LR causes lung barrier damage, which involves PP2A activity inhibition and enhancement of Claudin1 ubiquitination. This study broadens the awareness of the toxic effects of MC-LR on the respiratory system, which has deep implications for public health.

Pterostilbene attenuates intestinal epithelial barrier loss induced by high loading intensity of exercise

Mounting evidence suggested that high loading intensity of exercise might be detrimental to human health, especially the gastrointestinal tract. Pterostilbene (PTE), derived from grapes and blueberries, might reach a high concentration of intestinal contents. Our study aimed to evaluate PTE’s ability to prevent the loss of intestinal epithelial barrier in high loading intensity of exercise. The exercise model was established by the forced running of mice. An effective HPLC-UV method was developed to quantify PTE concentration in intestinal content. The mRNA changes were detected by quantitative polymerase chain reaction (qPCR). The structure of intestinal flora was analyzed by 16S rRNA sequencing. The PTE (100 mg/kg/d) could significantly attenuate exercise-induced intestinal epithelial barrier loss. Moreover, the HPLC-UV assay showed that the PTE concentration of intestinal content could last 12 h. Furthermore, the exercise increased the abundance of Alistipes, which was related to lipopolysaccharide (LPS) production but could not be reversed by PTE intervention. Besides, cell experiments showed that PTE could promote the expression of intestinal epithelial tight junction (TJ) molecules in vitro. In conclusion, PTE has a significant interest in preventing exercise-induced intestinal damage.

Discoidin domain receptor 1(DDR1) promote intestinal barrier disruption in Ulcerative Colitis through tight junction proteins degradation and epithelium apoptosis

BACKGROUND AND AIMS

Discoidin domain receptor 1 (DDR1) encodes a receptor tyrosine kinase involved in multiple physiological and pathological processes. DDR1 is expressed in the intestinal epithelium, but its role in Ulcerative Colitis (UC) is poorly understand. This study aimed to identify the function of DDR1 in maintaining the homeostasis of UC.

METHODS

The DDR1 expression level in non-inflamed and inflamed colon samples from IBD patients were assessed. DDR1 knock-out (DDR1^-/-) and wild-type (WT) mice were administered dextran sulfate sodium (DSS) to induce colitis and assessed based on colitis symptoms. In addition, intestinal epithelial barrier injury was induced by TNF-α and IFN-γ incubation to cell monolayers transfected with PCDH-DDR1 or pLKO.1-sh-DDR1-1 plasmids. The effect of DDR1 in regulating barrier integrity, tight junctions (TJ) protein status, and cell apoptosis was investigated in vivo and in vitro. Furthermore, the activation of the NF-κB p65-MLCK-p-MLC2 pathway was also investigated.

RESULTS

Decreased DDR1 expression levels were observed at the inflamed sites compared with the non-inflamed. DDR1^-/- mice had alleviated intestinal mucosal barrier injuries, upregulated TJ proteins, decreased epithelium apoptosis from DSS-induced colitis, and reduced proinflammatory cytokines production in the colon. These findings were further confirmed in vitro. DDR1 over-expression aggravated the TNF-α/IFN-γ-induced TJ disruption, while DDR1 shRNA prevented TJ damage even in the presence of JSH-23. DDR1 dependently destroyed the intestinal barrier via the NF-κB p65-MLCK-p-MLC2 pathway.

CONCLUSION

Our findings revealed that DDR1 regulated the intestinal barrier in colitis by modulating TJ proteins expression and epithelium apoptosis, making it a potential target of UC.

Curcumin mitigates deoxynivalenol-induced intestinal epithelial barrier disruption by regulating Nrf2/p53 and NF-κB/MLCK signaling in mice

Deoxynivalenol (DON) induces intestinal epithelial barrier disruption, posing a threat to the body. Curcumin (Cur) possesses pharmacological bioactivities such as antioxidant and anti-inflammatory effects that help maintain intestinal health. Here, the protective effects of Cur against DON-induced intestinal epithelial barrier disruption were explored. Cur (75 or 150 mg/kg body weight [B.W.]) alleviated DON-induced (2.4 mg/kg B.W.) inhibition of growth performance and morphological damage to intestinal epithelium in mice. Cur also significantly attenuated DON-induced intestinal epithelial barrier disruption and structural damage to the tight junctions (TJs), as assessed by ultrastructure observation, serum FITC-dextran concentrations and diamine oxidase activity. Cur mitigated the DON-induced increase in reactive oxygen species, malondialdehyde and 8-hydroxy-2'-deoxyguanosine levels; p53, cytoplasmic cytochrome c, Bax, and Bcl-2 expression; and TUNEL-positive cell rate and caspase-3 activity. It decreased the total antioxidant capacity and expression of nuclear Nrf2 and its downstream target genes. Lastly, Cur attenuated the DON-induced increase in MLCK, p-MLC, nuclear NF-κB p65 expression, and the NF-κB downstream target genes; decrease in the expression of TJs proteins (claudin-1, occludin, and zonula occludens-1 [ZO-1]); and abnormal ZO-1 distribution. Overall, Cur mitigated the DON-induced disruption of the intestinal epithelial barrier by regulating the Nrf2/p53-mediated apoptotic pathway and NF-κB/MLCK-mediated TJs pathway in mice.

The Anti-Obesity and Anti-Inflammatory Capabilities of Pterostilbene and its Colonic Metabolite Pinostilbene Protect against Tight Junction Disruption from Western Diet Feeding

SCOPE

Tight junctions (TJs) are a member of the intestinal epithelium barrier that provides the first line of protection against external factors. Anti-obesity and protective effects of pterostilbene (PSB) on TJs have previously been reported, but the effect of its colonic metabolite, pinostilbene (PIN), is less understood.

METHODS AND RESULTS

A 16-week animal model fed with western-diet to induced colonic TJs disruption was designed, supplemented with PSB and PIN to evaluate their potent in colonic TJ protection. The results showed that both PSB and PIN exerted suppressive effects on obesity, hepatic steatosis, and chronic inflammation in western-diet-fed mice. Western-diet feeding significantly reduced expression of TJ proteins, including ZO-1, occludin, and claudin-1, while PSB and PIN supplementation effectively protected TJ proteins against disruption. Increment in serum, hepatic, and mesenteric pro-inflammatory cytokines suggest their probable involvement in TJ disruption supported with the findings in macrophage polarization. The adverse were revered by PSB and PIN. The protective effect of PSB and PIN on TJ proteins may stem from their anti-inflammation capabilities.

CONCLUSION

This is the first study suggesting that PIN, the metabolite of PSB, demonstrates a similar protective effect on colonic TJ proteins via its anti-obesity, hepatic protection and anti-inflammatory capabilities. This article is protected by copyright. All rights reserved.

Pterostilbene Coupled with Physical Exercise Effectively Mitigates Collagen-Induced Articular Synovial by Correcting the PI3K/Akt/NF-κB Signal Pathway

Studies have revealed that a novel anti-inflammatory mediator─maresin-1 (MaR1)─can reduce the level of inflammatory factors. There is evidence that physical exercise (PE) promotes the biosynthesis of MaR1, leading to the prevention of rheumatoid arthritis (RA). Previously, we have proven that resveratrol can mitigate the formation of RA. Pterostilbene (Pte) is an analogue of resveratrol, but it is around four times more bioavailable. Hence, we hypothesize that Pte could be more effective in preventing RA, in particular, when accompanied by moderate PE. Based on this hypothesis, we explored the preventive effect of Pte combined with PE on a bovine type II collagen (BIIC)-stimulated rat RA model and its underlying molecular mechanism. Compared with the BIIC-stimulated group, the serum content of MaR1 with continuous intervention of Pte plus PE for 8 weeks was significantly increased to 46.3 pg/mL from 7.2 pg/mL in BIIC-treated alone. Besides, the variation in the relative expression levels of p-NF-κB and p-Akt was reversed with the administration of Pte plus PE. More importantly, the in vitro results confirmed that the treatment of Pte plus MaR1 inhibited proliferation and apoptosis and promoted the autophagy of the interleukin (IL)-1β-stimulated primary rat synovial cells through the PI3K/Akt/NF-κB signal pathway. Collectively, the oral administration of Pte plus moderate PE helped to ameliorate the pathological process of RA by correcting the PI3K/Akt/NF-κB signal pathway.

Lactobacillus rhamnosus GG Ameliorated Long-Term Exposure to TiO2 Nanoparticles Induced Microbiota-Mediated Liver and Colon Inflammation and Fructose-Caused Metabolic Abnormality in Metabolism Syndrome Mice

A huge number of titanium dioxide nanoparticles (TiO₂ NPs) exist in confectionery foods, which is a high-risk factor for development of diet-induced metabolism syndrome (MetS). In this study, we built a high fructose drinking-induced MetS mouse model, and oral intake of 20 mg/kg TiO₂ NPs was administered for 8 weeks. Significant pathological changes and inflammatory factors of overproduction were detected in the liver and colon. The 16S rDNA sequencing analysis results indicated that TiO₂ NPs evidently and further perturbed the gut microbiota diversity, compositions, and KEGG pathways in MetS mice. Fecal microbiota transplant experiment proved that TiO₂ NPs-altered gut microbiota drives liver and colon inflammation damage. More importantly, oral supplementation of Lactobacillus rhamnosus GG (LGG) ameliorated not only the TiO₂ NPs-induced inflammation but also the fructose-caused metabolic abnormality. LGG recovered the gut dysbiosis and decreased the abundance of inflammation-related bacteria (Desulfovibrionaceae, Clostridia, and Proteobacteria), thereby protecting against TiO₂ NPs-induced severe inflammation damage. Our study suggests the necessity of assessing the toxic effects of foodborne nanoparticles on the chronic disease population and potential usefulness of probiotics as prophylactic and therapeutic.